TITLE OF THE INVENTION
USER IDENTIFICATION APPARATUS, TOUCH-SENSITIVE SYSTEM AND METHOD
BACKGROUND OF THE INVENTION
The present invention relates to the field of touch sensors, for example touch sensors for overlying a display screen to provide a touch-sensitive display (touch screen). In particular, embodiments of the invention relate to differentiating between users interacting with the touch sensor, particularly in the context of a vehicle, such as an automobile.
A capacitive touch sensor can be generalised as one that uses a physical sensor element comprising an arrangement of electrically conductive electrodes extending over a touch sensitive area (sensing area) to define sensor nodes and a measurement circuitry connected to the electrodes and operable to measure changes in the electrical capacitance of each of the electrodes or the mutual capacitance between combinations of the electrodes.
The electrodes are typically provided on a substrate. In conventional systems, a driver applies a signal (such as a time-varying current) to the array of electrodes. A user (or an object) when approaching or contacting the electrode array, electrically interacts with the driven electrode array and as such it is possible to detect the presence or absence of a user's touch, and in some cases, a relative position of the user's touch.
While such conventional systems have certain advantages, one disadvantage with such techniques is the ability to distinguish between different users or different objects interacting with the capacitive touch sensor. Indeed, in the above example where the electrode array is driven by a signal applied to the electrode array, when two users interact with the electrode array in substantially the same manner, the way in which the driven electrode array is affect is substantially the same regardless of the user. Hence, conventional systems are incapable of distinguishing between inputs received from different users.
There is therefore a desire to provide touch sensors or systems with the ability to distinguish between touches (inputs) received from different users. Moreover, there is a desire to allow for such distinction in a simple and cost effective manner.
SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided an apparatus for use with a touch-sensitive apparatus for identifying a user or object at, or in proximity of, a sensing surface of the touch-sensitive apparatus, the apparatus including: a user electrode; first drive circuitry for generating an identification signal to be applied to the user electrode; and second drive circuitry for generating a second signal to be applied to the user electrode, the second signal being different from the identification signal. In use, the identification signal is capable of capacitively coupling to a user of the apparatus such that when the user, or an object coupled to the user, interacts with the sensing surface of the touch-sensitive apparatus, the identification signal is capable of capacitively coupling to a touch-sensitive electrode of the touch-sensitive apparatus. The second drive circuitry is configured to generate the second signal to cause the user electrode to perform a different function.
According to a second aspect of the invention there is provided a system including: a touch-sensitive apparatus for sensing one or more touches or objects at a sensing surface; and the apparatus of the first aspect. The touch-sensitive apparatus includes: at least one touch-sensitive electrode defining a sensing surface; touch-sensing drive circuitry configured to generate a touch-sensing drive signal to be applied to the at least one touch-sensitive electrode; receiver circuitry configured to couple to the at least one touch-sensitive electrode and receive signals from the at least one touch-sensitive electrode; and a controller configured to receive signals from the receiver circuitry and determine a property of a touch or object sensed at the sensing surface. The controller is configured to determine, from the received signals from the receiver circuitry, whether the received signals contain a component corresponding to the identification signal, and if so, to determine the sensed touch or object is coupled to the user electrode.
According to a third aspect of the invention there is provided a user identification apparatus for use with a touch-sensitive apparatus for identifying a user or object at, or in proximity of, a sensing surface of the touch-sensitive apparatus, the user identification apparatus including: first drive circuitry for generating an identification signal to be applied to an electrode, wherein the identification signal is set so as to be detectable by a touch-sensitive apparatus comprising at least one touch-sensitive electrode; and coupling elements for enabling the first drive circuitry to be connected to the electrode of a vehicle, the electrode of the vehicle being configured to perform at least one of a heating function and a proximity detection function.
According to a fourth aspect of the invention there is provided a method of operating a touch-sensitive apparatus for identifying a user or object at, or in proximity of, a sensing surface of the touch-sensitive apparatus, wherein the method includes: applying an identification signal to a user electrode arranged to capacitively couple to a user; detecting a touch or object at, or in proximity of, the sensing surface of the touch-sensitive apparatus, the sensing surface defined by at least one touch-sensitive electrode of the touch-sensitive apparatus, by receiving signals from the at least one touch-sensitive electrode; determining, from the received signals, whether the received signals contain a component corresponding to the identification signal, and if so, determining the sensed touch or object is coupled to the user electrode. The method further comprises applying a second signal to the user electrode to cause the user electrode to perform a different function.
According to a fifth aspect of the invention there is provided use of a user electrode configured to implement either of a heating function or an occupancy detection function in a seat to identify a user or object at, or in proximity of, a sensing surface of a touch-sensitive apparatus.
It will be appreciated that features and aspects of the invention described above in relation to the first and other aspects of the invention are equally applicable to, and may be combined with, embodiments of the invention according to other aspects of the invention as appropriate, and not just in the specific combinations described above.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is now described by way of example only with reference to the following drawings in which: Figure 1 schematically illustrates a touch sensitive apparatus in accordance with certain embodiments of the invention; Figure 2 schematically illustrates a self-capacitance measurement mode of the touch sensitive apparatus, specifically with a view to explaining the principles of self capacitance measurement; Figure 3 schematically illustrates a mutual-capacitance measurement mode of the touch sensitive apparatus, specifically with a view to explaining the principles of mutual capacitance measurement; Figure 4 schematically illustrates a system in accordance with the principles of the disclosure, specifically showing a signal generation apparatus coupled to a user electrode provided in a seat; Figure 5 schematically illustrates a first implementation of the user identification drive circuitry and secondary drive circuitry coupled to a user electrode in accordance with the principles of the present disclosure; Figure 6 schematically illustrates a modification of the first implementation of the user identification drive circuitry and secondary drive circuitry coupled to a user electrode of Figure 5, in particular showing a modification that allows retrofitting, in accordance with the principles of the present disclosure; Figure 7 schematically illustrates a second implementation of the user identification drive circuitry and secondary drive circuitry coupled to a user electrode in accordance with
the principles of the present disclosure;
Figure 8 schematically illustrates a first implementation of the user identification drive circuitry and secondary drive circuitry provided as an integrated unit and coupled to a user electrode in accordance with the principles of the present disclosure; Figure 9 schematically illustrates a system in accordance with the principles of the disclosure, in which a first signal generation apparatus is coupled to a first user electrode provided in a first seat and a second signal generation apparatus is coupled to a second user electrode provided in a second seat; Figure 10 schematically illustrates an example system that employs the touch-sensitive apparatus of Figure 1; and Figure 11 is a flow diagram representing an example method for utilising the systems of Figures 4 and 9 in accordance with the present disclosure.
DETAILED DESCRIPTION
The present disclosure relates broadly to an apparatus for use with a touch-sensitive apparatus for identifying a user or object at, or in proximity of, a sensing surface of the touch-sensitive apparatus. The apparatus comprises a common or user electrode that is capable of being applied with a user identification signal to perform a function of identifying a user or a secondary drive signal for performing a secondary function. The function of identifying a user is in the context of a user interacting with the touch-sensitive apparatus; namely, to determine whether a detected touch or object at the sensing surface of the touch-sensitive apparatus is a touch or object associated with (i.e., originating from or belonging to) a user that is capacitively coupled to the user electrode. The secondary function is a function that is generally unrelated to the user identification function. For example, the secondary function may be a heating function (to cause the user electrode to heat to provide warmth) or an occupancy detection function (to determiner whether a user is near to the electrode). The system may find particular application in a vehicle or the like, with the user electrode being implemented in a seat of the vehicle. Because the common or user electrode is used to perform multiple functions, the overall cost and complexity of systems used to deliver both functions can be reduced. Moreover, in some instances, systems that deliver only the second function can be retrofit with a system to deliver the user identification function in addition to the second function.
Figure 1 schematically shows an example of a touch-sensitive apparatus 1. The touch-sensitive apparatus 1 is represented in plan view (to the left in the figure) and also in cross-sectional view (to the right in the figure).
The touch-sensitive apparatus 1 comprises a sensor element 100, measurement circuitry 105, processing circuitry 106, and cover 108. The sensor element 100 and cover 108 may, more generally be referred to as a touch screen or touch-sensitive element of the touch-sensitive apparatus 1, while the measurement circuitry 105 and processing circuitry 106 may, more generally, be referred to as the controller of the touch-sensitive apparatus 1. The touch-sensitive element is primarily configured for establishing the position of a touch within a two-dimensional sensing area by providing Cartesian coordinates along an X-direction (horizontal in the figure) and a Y-direction (vertical in the figure). In this implementation, the sensor element 100 is constructed from a substrate 103 that could be glass or plastic or some other insulating material and upon which is arranged an array of electrodes consisting of multiple laterally extending parallel electrodes, X-electrodes 101 (row electrodes), and multiple vertically extending parallel electrodes, Y-electrodes 102 (column electrodes), which in combination allow the position of a touch 109 to be determined. To clarify the terminology, and as will be seen from Figure 1, the X-electrodes 101 (row electrodes) are aligned parallel to the X-direction and the Y-electrodes 102 (column electrodes) are aligned parallel to the Y-direction. Thus the different X-electrodes allow the position of a touch to be determined at different positions along the Y-direction while the different Y-electrodes allow the position of a touch to be determined at different positions along the X-direction. That is to say in accordance with the terminology used herein, the electrodes are named (in terms of X-and Y-) after their direction of extent rather than the direction along which they resolve position. Furthermore, the electrodes may also be referred to as row electrodes and column electrodes. It will however be appreciated these terms are simply used as a convenient way of distinguishing the groups of electrodes extending in the different directions. In particular, the terms are not intended to indicate any specific electrode orientation. In general, the term "row" will be used to refer to electrodes extending in a horizontal direction for the orientations represented in the figures while the terms "column" will be used to refer to electrodes extending in a vertical direction in the orientations represented in the figures. The X-electrodes 101 and Y-electrodes 102 define a sensing (or sense) area or surface, which is a region of the substrate 103 which is sensitive to touch. In some cases, each electrode may have a more detailed structure than the simple "bar" structures represented in Figure 1, but the operating principles are broadly the same.
The sensor electrodes are made of an electrically conductive material such as copper or Indium Tin Oxide (ITO). The nature of the various materials used depends on the desired characteristics of the touch-sensitive apparatus. For example, a touch-sensitive element of the touch-sensitive apparatus 1 may need to be transparent (for example if it overlays a display), in which case ITO electrodes and a plastic substrate are common. On the other hand, a touch pad, such as often provided as an alternative to a mouse in laptop computers is usually opaque, and hence can use lower cost copper electrodes and an epoxy-glass-fibre substrate (e.g. FR4). Referring back to Figure 1, the electrodes 101, 102 are electrically connected via circuit conductors 104 to measurement circuitry 105, which is in turn connected to processing circuitry 106 by means of a circuit conductor 107. The measurement circuitry 105 and / or the processing circuitry 106 may each be provided by a (micro)controller, processor, ASIC or similar form of control chip. Although shown separately in Figure 1, in some implementations, the measurement circuitry 105 and the processing circuitry 106 may be provided by the same (micro)controller, processor, ASIC or similar form of control chip. The measurement circuitry 105 and / or the processing circuitry 106 may be comprised of a printed circuit board (PCB), which may further include the various circuit conductors 104, 107. The measurement circuitry 105 and the processing circuitry 106 may be formed on the same PCB, or separate PCBs. Note also that the functionality provided by either of the measurement circuitry 105 and the processing circuitry 106 may be split across multiple circuit boards and / or across components which are not mounted to a PCB. The processing circuitry 106 interrogates the measurement circuitry 105 to recover the presence and coordinates of any touch or touches present on, or proximate to, the sensor element 100.
Generally speaking, the measurement circuitry 105 is configured to perform capacitance measurements associated with the electrodes 101, 102 (described in more detail below). The measurement circuitry 105 outputs the capacitance measurements to the processing circuitry 106, which is arranged to perform processing using the capacitance measurements. The processing circuitry 106 may be configured to perform a number of functions, but at the very least is configured to determine when a touch 109, caused by an object such a human finger or a stylus coming into contact with the sensing surface of the sensor element 100, is sensed or detected at the sensing surface with appropriate analysis of relative changes in the electrodes' measured capacitance / capacitive coupling. This determination process is described in more detail below. The processing circuitry 106, as in the described implementation, may also be configured to, with appropriate analysis of relative changes in the electrodes' measured capacitance / capacitive coupling, calculate a touch position on the cover's surface as an XY coordinate 111. In some implementations, the processing circuitry 106 may also be configured to establish whether an object "hovers" over the sensing surface of the sensor element 100, that is, the object is within a distance of the sensing surface that the sensing surface can reliably detect the hovering object, but the hovering object is not in contact with the sensing surface of the sensing element 100. In some implementations, the processing circuitry 106 may also be configured to sense a position of the hovering object. For convenience, an object being directly in contact with the sensing surface of the sensing element 100 or hovering above the sensing surface of the sensor element 100 will herein both be referred to as a touch unless otherwise stated. It should be appreciated that the underlying mechanism for determining the presence and/or position of a touch is broadly similar in either case (where it may be that only the various thresholds for determining a touch, i.e., changes in capacitance, are different for the different scenarios).
In the example of Figure 1, a front cover (also referred to as a lens or panel) 108 is positioned in front of the substrate 103 and a single touch 109 on the surface of the cover 108 is schematically represented. Note that the touch itself does not generally make direct galvanic connection to the substrate 103 or to the electrodes 102. Rather, the touch influences the electric fields 110 that the measurement circuitry 105 generates using the electrodes 102 (described in more detail below).
A further aspect of capacitive touch sensors / touch-sensitive apparatus 1 relates to the way the measurement circuitry 105 uses the electrodes of the sensor element to make its measurements. There are two main techniques for measuring capacitance, which are described below. Capacitive touch sensors may generally be configured to operate exclusively using one or the other of the two techniques, or a combination of the two (e.g., in a time-division multiplexed manner).
A first technique is based on measuring what is frequently referred to as "self-capacitance". Reference is made to Figure 2. In Figure 2, an electrical stimulus (herein touch-sensing drive signal) 113 is applied to one or more of the electrodes 101, 102 which will cause an electric field 110 to form around it. This field 110 couples through the space around the electrode back to the measurement circuitry 105 via numerous conductive return paths that are part of the nearby circuitry of the sensor element 100 and the product housing (shown schematically by reference numerals 114), or physical elements from the nearby surroundings 115 etc., so completing a capacitive circuit 116. The overall sum of return paths is typically referred to as the "free space return path" in an attempt to simplify an otherwise hard-to-visualize electric field distribution. The important point to realise is that the capacitance measured by the measurement circuitry 105 is the "self-capacitance" of the sensor electrode (and connected tracks) that is being driven relative to free space (or Earth as it is sometimes called) i.e. the "self-capacitance" of the relevant sensor electrode.
Touching or approaching the electrode with a conductive element, such as a human finger, causes some of the field to couple via the finger through the connected body 118, through free space and back to the measurement circuitry 105. This extra return path 119 can be relatively strong for large objects (such as the human body), and so can give a stronger coupling of the electrode's field back to the measurement circuitry 105; touching or approaching the electrode hence increases the self-capacitance of the electrode. The measurement circuitry 105 is configured to sense this increase in capacitance. The increase is strongly proportional to the area 120 of the applied touch 109 and is normally weakly proportional to the touching body's size (the latter typically offering quite a strong coupling and therefore not being the dominant term in the sum of series connected capacitances).
In the described implementation, the electrodes 101, 102 are arranged on an orthogonal grid, generally with a first set of electrodes on one side of a substantially insulating substrate 103 and the other set of electrodes on the opposite side of the substrate 103 and oriented at substantially 90° to the first set. In other implementations, the electrodes may be oriented at a different angle (e.g., 30°) relative to one another. In addition, it should also be appreciated that it is also possible to provide structures where the grid of electrodes is formed on a single side of the substrate 103 and small conductive bridges are used to allow the two orthogonal sets of electrodes to cross each other without short circuiting. However, these designs are more complex to manufacture and less suitable for transparent sensors. Regardless of the arrangement of the electrodes, broadly speaking, one set of electrodes is used to sense touch position in a first axis that we shall call "X" and the second set to sense the touch position in the second orthogonal axis that we shall call "Y".
When the measurement circuitry 105 operates in accordance with the self-capacitance measuring mode, the measurement circuitry 105 can either measure each electrode in turn (sequential) with appropriate switching of a single control channel (i.e., via a multiplexer) or it can measure them all in parallel with an appropriate number of separate control channels. In the former sequential case, any neighbouring electrodes to a selected electrode are sometimes grounded by the measurement circuitry 105 to prevent them becoming touch sensitive when they are not being sensed (remembering that all nearby capacitive return paths will influence the measured value of the actively driven electrode). In the case of the parallel measurement scheme, in the absence of a touch the nature of the measurements received by all the electrodes is typically the same so that the instantaneous voltage on each electrode is approximately the same. In this way, each electrode has minimal influence on its neighbours (the electrode-to-electrode capacitance is non-zero but its influence is only "felt" by the measurement circuitry 105 if there is a voltage difference between the electrodes).
A second technique is based on measuring what is frequently referred to as "mutual-capacitance". Reference is made to Figure 3. In Figure 3, a transmitter (driven/drive) electrode, shown as the X electrodes 101 in Figure 3, is driven by a stimulus 113 (herein also referred to as a touch-sensing drive signal). In conventional systems, the touch-sensing drive signal is applied directly to the driven electrodes. The touch-sensing drive signal 113 is coupled to one or more receiver electrodes, by virtue of the driven electrodes proximity to an array of receiver electrodes, shown as the Y electrodes 102 in Figure 3. (It should be appreciated that the Y electrodes 102 may instead be the transmitting electrodes and the X electrodes 101 may instead be the receiving electrodes in other implementations). The resulting electric field 110 is now directly coupled from the transmitter electrode to each of the nearby receiver electrodes; the "free space" return path discussed above plays a negligible part in the overall coupling back to the measurement circuitry 105 when the sensor element 100 is not being touched. The area local to and centred on the intersection of a transmitter and a receiver electrode is typically referred to as a "node" or "intersection point". In the conventional case, where the touch-sensing drive signal is applied to a driven electrode, on application or approach of a conductive element such as a human finger, the electric field 110 is partly diverted to the touching object. An extra return path to the measurement circuitry 105 is now established via the body 118 and "free-space" in a similar manner to that described above. However, because this extra return path acts to couple the diverted field directly to the measurement circuitry 105, the amount of field coupled to the nearby receiver electrode 102 decreases relative to the situation where no body 118 is present. This is measured by the measurement circuitry 105 as a decrease in the "mutual-capacitance" between that particular transmitter electrode and receiver electrodes in the vicinity of the touch 109. The measurement circuitry 105 senses this change in capacitance of one or more nodes. For example, if a reduction in capacitive coupling to a given Y-electrode is observed while a given X-electrode is being driven, it may be determined there is a touch in the vicinity of where the given X-electrode and given Y-electrode cross, or intersect, within the sensing area of the sensor element 100. The magnitude of a capacitance change is nominally proportional to the area 120 of the touch (although the change in capacitance does tend to saturate as the touch area increases beyond a certain size to completely cover the nodes directly under the touch) and weakly proportional to the size of the touching body (for reasons as described above). The magnitude of the capacitance change also reduces as the distance between the touch sensor electrodes and the touching object increases.
As described above, the transmitter electrodes and receiver electrodes in the described implementation are arranged as an orthogonal grid, with the transmitter electrodes on one side of a substantially insulating substrate 103 and the receiver electrodes on the opposite side of the substrate 103. This is as schematically shown in Figure 3. As in Figure 2, the first set of transmitter electrodes 101 shown on one side of a substantially insulating substrate 103 and the second set of receiver electrodes 102 is arranged at nominally 90° to the transmitter electrodes on the other side of the substrate 103. In other implementations, the electrodes may be oriented at a different angle (e.g., 30°) relative to one another. In addition, other implementations may have structures where the grid is formed on a single side of the substrate and small insulating bridges, or external connections, are used to allow the transmitter and receiver electrodes to be connected in rows and columns without short circuiting.
Depending on the application at hand, the touch-sensitive apparatus 1 may be configured to operate using one or both of the abovementioned measurement techniques. Mutual capacitance measurement techniques offer the ability to resolve multiple touches at different locations on the touch-sensitive element, and while self-capacitance measurement techniques do not, as a matter of course, provide this functionality, self-capacitance measurement techniques generally output a much stronger signal thus increasing the sensitivity of the touch-sensitive element.
In some conventional touch-sensitive apparatuses, the touch-sensing drive signal for obtaining the mutual or self-capacitance measurements is provided to the electrode array 101, 102 via suitable circuitry that is physically connected or coupled to the touch-sensitive apparatus 1. For example, the measurement circuitry 105 may be provided with touch-sensing drive circuitry 120 (shown in Figure 3 in more detail, although it should be appreciated that the touch-sensing drive circuitry 120 may be applied to the implementations of Figures 1 and 2). The touch-sensing drive circuitry 120 is configured to generate one or more touch-sensing drive signals 113 (for example, taking the form of a time-varying voltage or current, such as a sinusoidal voltage or current). The touch-sensing drive signal 113 generated by the touch-sensing drive circuitry 120 is then applied to a given drive electrode of the electrode array 101, 102. For example, the measurement circuitry 105 may couple to a first terminal 117 of an electrode of the electrode array and supply the touch-sensing drive signal 113 accordingly. A measurement of the capacitance (self-or mutual capacitance) can be obtained using the techniques discussed above.
Broadly speaking, regardless of the technique used to obtain the measurement of the capacitance, the processing circuitry 106 is configured to detect a touch or object at or in the proximity of the sensing surface based on a change in the capacitance measurements. This may typically be due to a difference between the corresponding measurement (for an electrode or electrodes) made in the absence of a touch / object to the corresponding measurement made in the presence of a touch / object. For example, when the difference exceeds a threshold, the processing circuitry 106 may be configured to determine that a touch is present. Accordingly, the processing circuitry 106 may output, or cause the output of, a signal indicative of information concerning the touch (presence, location, hover/contact, etc.), which may be received and processed by a corresponding host controller or the like. It should be appreciated that the measurements in the absence of a touch may be obtained in advance, e.g., as part of a calibration process, or may be routinely obtained during use of the touch-sensitive apparatus 1 (noting that typically a touch is likely to be detected for a fraction of the operational time of the touch-sensitive apparatus 1).
Typically, to perform a full scan of the electrode array (that is, where the capacitance associated with each electrode or each intersection of the electrode array is measured), the touch-sensing drive signal is applied to each of the transmit electrodes (in the case of mutual capacitance measurement techniques) or each of the electrodes (in the case of self-capacitance measurement techniques) of the electrode array and corresponding measurements are made. This may include applying the touch-sensing drive signal sequentially to various electrodes of the electrode array and/or applying the drive signal (or multiple drive signals) to the various electrodes of the electrode array.
As described above, based on the signals received from the sensor element 100, the controller (e.g., the measurement circuitry 105 and processing circuitry 106) is capable of determining, as a property of the detected touch or object, at least one of: the presence of a touch or object at the sensing surface, a position on the sensing surface of the touch or object, and a distance relative to the sensing surface of the touch or object (e.g., such as whether the object is hovering over the sensing surface).
However, the touch-sensitive apparatus 1 alone is, typically, unable to determine the origin of a touch or object. For example, in the situation that two users interact with the touch-sensitive apparatus 1, the touch-sensitive apparatus 1 is unable to identify whether a detected touch originates or belongs to the first user or the second user. That is, the change in capacitance as sensed by the electrode array 101, 102 is broadly the same regardless of whether the touch is performed by the first user or the second user.
Figure 4 is a schematic representation of a system in accordance with aspects of the present disclosure. The system comprises the touch-sensitive apparatus 1 of Figure 1 (shown highly schematically in Figure 4, with certain components not being shown to improve the clarity thereof), in addition to a signal generation apparatus 150. That is to say, the touch-sensitive apparatus 1 and signal generation apparatus 150 together form the system of Figure 4. Also shown in Figure 4 is a first user, U 1.
The signal generation apparatus 150 comprises a user electrode 151, user identification drive circuitry 152, and secondary drive circuitry 153. The user electrode 151 and the user identification drive circuitry 152 are electrically connected with one another, e.g., through suitable wiring / circuitry as schematically shown in Figure 4. Additionally, the user electrode 151 and the secondary drive circuitry 153 are electrically connected with one another, e.g., through suitable wiring / circuitry as schematically shown in Figure 4.
As shown in Figure 4, the first user U1 is provided in the proximity of the user electrode 151. In Figure 4, the user U1 is shown sitting on a seat 160 which may, for example, represent the seat 160 of a vehicle such as an automobile, or the like, although the seat 160 may be any seat. The user electrode 151 is shown positioned below the first user U1, in the base of the seat 160. However, the user electrode 151 may be arranged in any suitable manner so as to be capable of being in proximity of the user U1. For example, in other implementations, the user electrode 151 may be arranged in the back (e.g., the section supporting the user's back) of the seat 160. In other implementations, the seat 160 may be omitted and the user electrode 151 may form a floor on which the user U1 stands.
The user electrode 151 may be configured in any suitable manner. For example, the user electrode 151 may be configured as a sheet of a conductive material, e.g., a metal, or as a series of interconnected wires or the like forming a mesh-like structure. In accordance with the principles of the present disclosure, the user electrode 151 is controlled to perform different functions, as will explained in more detail below, depending upon the nature of an electrical signal applied to the user electrode 151. Therefore, the form or structure of the user electrode 151 may be set in dependence on the functions to be performed. For example, if the particular function is more suited to a sheet-type electrode, then the user electrode may take the form of a sheet of conductive material. In some instances, depending on the requirements of the different functions to be performed, some degree of compromise may be considered in order to provide acceptable performance for the given functions.
The user identification drive circuitry 152 is configured to generate an identification signal to be applied to the user electrode 151. The identification signal is an electrical signal, such as a time-varying electrical signal (e.g., voltage and/or current). When the user U1 is in proximity of the user electrode 151, e.g., the user U1 is positioned on the seat 160 as shown in Figure 4, the user identification signal is capable of capacitively coupling to the user U1 via the user electrode 151. That is, the identification signal as applied to the user electrode 151 causes, through a capacitive coupling with the user U1, a corresponding user identification signal to be present in (or coupled to) the first user U1 while the user electrode 151 is being driven by the user identification signal. The user identification drive circuitry 152 may be configured in any suitable way to generate the user identification signal at a suitable level so as to couple to the first user U1 when applied to the user electrode 151. The specific magnitude of the user identification signal may be dependent on several factors including the design of the user electrode 151, the frequency and/or form of the user identification signal, and the structure of any component the user electrode 151 is provided in (e.g., the seat 160).
When the user identification signal is applied to the user electrode 151, as described above, the user identification signal couples to the user U1. When the user U1 subsequently interacts with the touch-sensitive apparatus 1, provided the user identification signal is coupled to the user U1 at a suitable strength, the user identification signal is subsequently capable of capacitively coupling to the touch-sensitive apparatus 1 (or more specifically, the associated electrodes 101, 102 thereof). This is schematically illustrated in Figure 4 as shown by a capacitive coupling between the user U1 and the sensing element 100 of the touch-sensitive apparatus 1.
The user identification signal may be considered similar to the touch-sensing drive signal in that both are time-varying electrical signals. Accordingly, the user identification signal when capacitively coupled to the electrode(s) of the touch-sensitive apparatus 1 is capable of influencing the measurement signals of the sensor element 100 (i.e., electrodes 101, 102) received by the measurement circuitry 105. In particular, the received measurement signals include a component that is dependent on the user identification signal. In some implementations, the user identification signal while being similar to the touch-sensing drive signal may be made to differ from the touch-sensing drive signal in at least one parameter. For example, the identification signal may be arranged to have a different form (e.g., square-wave, sinusoidal, triangular, etc.) or be configured to vary at a different frequency as compared to the touch-sensing drive signal. Accordingly, the processing circuitry 106 is configured to receive the measurement signals from the measurement circuitry 105 and, aside from determining at least one of the presence of a touch or object at the sensing surface, a position on the sensing surface of the touch or object, and a distance relative to the sensing surface of the touch or object (e.g., such as whether the object is hovering over the sensing surface), as described above, the processing circuitry 106 is further configured to identify whether the received measurement signals include a component corresponding to the user identification signal (e.g., such as a variation in the received measurement signal that corresponds to the form / frequency of the user identification signal). In the event that the processing circuitry 106 determines the received measurement signals include a component corresponding to the user identification signal, the processing circuitry 106 is able to determine that the touch or object detected from the received measurement signals belongs to or originates from the first user U1 capacitively coupled to the identification signal.
In some implementations, the user identification signal is a time-varying signal, such as a sinusoidal signal. The sinusoidal signal may be configured to vary with a frequency of 10 kHz or greater. Accordingly, when the processing circuitry 106 identifies a component of the measurement signals received from the measurement circuitry 105 having a frequency of 10 kHz or greater, the processing circuitry 106 determines that the detected touch or object originates from or belongs to a user capacitively coupled to the user electrode 151.
Hence, by applying the user identification signal to a user U1, e.g., via the user electrode 151, the touch-sensitive apparatus 1 is capable of determining whether a touch or objected sensed by the touch-sensitive apparatus 1 belongs to a user capacitively coupled to the user electrode 151 (based on the presence or absence of a component corresponding to the user identification signal). When the user identification drive circuitry 152 is controlled to apply the user identification signal to the user electrode 151, the user electrode 151 may be said to be performing the function of user identification (and hence the user electrode 151 may be referred to as a user identification electrode 151 in such instances).
However, in accordance with the principles of the present disclosure, the user electrode 151 may be controlled to perform an additional function, i.e additional to the function of user identification.
As shown in Figure 4, the signal generation apparatus 150 further comprises secondary drive circuitry 153. The configuration of the secondary drive circuitry 153 may be dependent on the additional function that the user electrode 151 is controlled to perform. In the present implementation, the user electrode 151 is controlled to perform the function of a heater element. In particular, the user electrode 151 is configured to cause warming of the seat 160 when the user electrode 151 is supplied with a secondary drive signal from the secondary drive circuitry 153 (to provide a so-called "heated seat" function). The secondary drive signal may take any suitable form to cause such heating of the user electrode 151. For example, the secondary drive signal may be a DC signal set at a suitable current level to causes resistive heating of the user electrode 151. The DC signal may be supplied continuously or in a modulated manner (e.g., through pulse-width modulation, PWM). Accordingly, when the secondary drive signal is applied to the user electrode 151, the user electrode 151 is capable of performing a heating function to cause the user electrode 151 to heat and, in this example, warm the seat 160.
However, the secondary function is not limited to solely a heating function, and in other implementations, the secondary function may be a further function. For example, in some implementations, the user electrode 151 may be configured to act as an occupancy detector for detecting whether the user U1 is present in the seat 160. In such implementations, the user electrode 151 may be configured to act as a contact sensor (e.g., in combination with a corresponding terminal or the like) that is brought into contact with the terminal when a user U1 sits on the seat (and thus applies a force to the user electrode 151 causing the user electrode 151 to move towards the terminal and complete a circuit with the terminal). The secondary drive signal applied to the user electrode 151 is capable of being received at the terminal when the user electrode 151 and terminal are brought into contact with each other and suitable circuitry (not shown) may be arranged to determine the seat 160 is occupied when the secondary signal is received at the terminal. Alternatively, the capacitance between the user electrode 151 and the terminal may also be measured and used to determine the occupancy of the seat 160. Other configurations of the occupancy detection sensing function may also be implemented. For example, in some instances, the user electrode 151 may include parts that change their resistance in response to stresses and strains caused by the presence of the user U1 in the seat 160. The secondary drive signal may be used to allow a resistance measurement of the user electrode 151 to be made, for example using suitable circuitry (not shown).
In accordance with the principles of the present disclosure, the user identification apparatus comprises a user electrode 151 that is capable of being controlled to perform a first function of user identification (and more specifically the identification of the user responsible for a sensed touch or object detected at the touch-sensitive apparatus 1) and to perform a second function, different to the first function, by virtue of the drive signals applied to the user electrode 151. The user electrode 151 may therefore be considered a common electrode in that it is common to (i.e., used for) both functions. Accordingly, it should be appreciated that it is not necessary to implement separate electrodes for each of the different functions, and that the two functions can be implemented using a common user electrode 151. This can help reduce the cost and material components required to implement both of these functions -for instance, the number of electrodes provided, in this example, in the seat 160 can be reduced to a single electrode.
Moreover, the present disclosure is also capable of being used with user electrodes 151 designed or provided for the purpose of implementing the secondary function. In other words, the user electrode 151 may be provided for the purposes of, e.g., warming the seat 160, and in accordance with the present disclosure, the electrode can be used to additionally provide the function of user identification. This may be in the context of new systems, i.e., designed with the intention of the electrode being used for a dual purpose but with the main reason for the electrode being present to enact the secondary function, but also older or existing systems where the user identification drive circuitry 152 may be retrofit to systems already having an electrode 151 but not necessarily designed or intended for the purpose of identifying a user. In this regard, while Figure 4 discloses the signal generation apparatus 150, it should be appreciated that the user identification drive circuitry 152 may be a separate (e.g., standalone) component of the signal generation apparatus 150 that is capable of being coupled to the electrical connection between the secondary drive circuitry 153 and the user electrode 151.
Figures 5 to 8 represent different ways in which the user identification drive circuitry 152 and the secondary drive circuitry 153 can be coupled to the user electrode 151 in order to perform both the identification function and the secondary function.
Figure 5 schematically represents the connection of the user identification drive circuitry 152 and the secondary drive circuitry 153 to the user electrode 151 according to a first implementation. Figure 5 represents a schematic circuit diagram with components relevant to the principles of the present disclosure being shown. It should be appreciated that the circuit of Figure 5 may include other components and/or connections in practical implementations (for example, various connections to power sources, or to ground, etc.).
Figure 5 shows the secondary drive circuitry 153 coupled to the user electrode 151.
In particular, the secondary drive circuitry 152 is coupled to what may be considered an input of the user electrode 151 through a conductor (such as wiring) that comprises a first inductor L1. What may be considered the output of the user electrode 151 is shown coupled to ground (or another reference potential) through another conductor (such as wiring) that comprises a second inductor L2.
In addition, Figure 5 shows the user identification circuitry 152 coupled between the inductor L1 and the input of the user electrode 151. The user identification circuitry 152 is coupled using a suitable conductor (such as wiring) that comprises a first capacitor C1.
Hence, broadly speaking, the arrangement in Figure 5 may be considered to represent a first circuit comprising a serial connection of the secondary drive circuitry 153 and the user electrode 151 with ground (or another reference potential), with a connection of the user identification circuitry 152 as a second circuit capable of providing an input signal (i.e., the user identification signal) to the first circuit.
As described above, in some implementations, the output of the secondary drive circuitry 153 is a DC signal, which is either continuously output or is modulated, e.g., such as pulse width modulated. The first and second inductors L1, L2 allow the DC signal to pass substantially unaffected through the inductors L1, L2. In some implementations, the inductor L1 in particular may provide a smoothing or filtering effect on the DC signal as it passes through the first inductor L1 to remove any time-varying components that may be present in the DC signal (e.g., due to any imperfections in generating the DC signal and/or due to any modulation that may be performed).
As described above, in some implementations, the output of the user identification drive circuitry 152, i.e., the user identification signal, is a time-varying electrical signal, e.g., a sinusoidal signal. The user identification signal is able to provide to the user electrode 151, firstly by passing through the capacitor C1, which in essence, does not have any significant impact on the transmission of the time-varying electrical signal across the capacitor C1, and secondly by passing to the user electrode 151 via the circuitry provided between the first inductor L1 and the input to the user electrode 151.
The first and second inductors Li, L2 and the capacitor C1 and associated connections may be referred to herein as decoupler circuits (or coupler-decoupler circuits).
For example, the first and second inductors Li, L2 may be considered to represent a first decoupler circuit. As noted above, the DC signal output from the secondary drive circuitry 153 is capable of passing through the first inductor L1 substantially unaffected. However, the user identification signal, which is a time-varying electrical signal, is in effect blocked by the first inductor L1 from passing along the relevant conductor to the secondary drive circuitry 153. Equally, the user identification signal is also blocked by the second inductor L2 from passing to ground (and depending on the requirement to prevent the user identification from passing to ground or other elements of the circuitry, the second inductor L2 may be optional). Accordingly, the inductor L1 can help protect the secondary drive circuitry 153 from any adverse effects that application of the time-varying user identification signal would otherwise have on the secondary drive circuitry 153.
Equally, the capacitor C1 may be considered to represent a second decoupler circuit. The capacitor C1 allows the transmission of the time-varying electrical signal (the user identification signal) across the capacitor plates in a substantially unaffected way. However, the DC signal output from the secondary drive circuitry 153 is in effect blocked by the capacitor C1 from passing along the relevant conductor to the user identification drive circuitry 152. Accordingly, the capacitor C1 can help protect the user identification drive circuitry 152 from any adverse effects that application of the secondary drive signal would otherwise have on the user identification drive circuitry 152. This may be particularly the case when considering a secondary drive signal that causes heating of the user electrode 151 (i.e., performing the function of a heater) as the DC signal may be relatively high (e.g., the current may be high) in order to effect a desired level of heating.
Hence, the first decoupler circuit helps to decouple the secondary drive signal from the user identification signal while the second decoupler circuit helps to decouple the user identification signal from the secondary drive signal to thereby provide a level of protection to the various drive circuitries 152, 153. However, it should be appreciated that the arrangement of the decoupler circuits permits both the user identification signal and the secondary drive signal to be applied to the user electrode 151. The user identification signal and the secondary drive signal may be applied simultaneously (for example, when both the user identification and heating functions are enabled) or individually depending on the particular circumstances. When the user identification signal and the secondary drive signal are applied simultaneously it should be appreciated that the user electrode 151 performs both functions of heating (or more generally the secondary function) and user identification simultaneously. In this regard, because the user identification signal is capacitively coupled to the user U1, the presence of the DC signal on the user electrode 151 has no significant effect on the coupling of the user identification signal to the user U1 (in much the same way as the capacitor Cl, the DC signal is effectively blocked by the capacitive coupling between the user electrode 151 and the user U1).
Hence, the circuitry of Figure 5 allows the user electrode 151 to be driven by both the user identification signal and the secondary drive signal, either separately or simultaneously. The circuitry of Figure 5 may be particularly suited to implementations where the secondary drive signal is a DC signal (or a constant, i.e., not time-varying).
In some implementations, the inductors L1 and L2 may also be constructed as a common mode choke, where the two windings (e.g., of wire) are formed on a common magnetic core. This may have advantages for higher peak current handling for heating and/or improved inductive isolation of the identification drive signal from the secondary drive circuitry 153.
The implementation of Figure 5 is also suitable for retrofitting of the user identification drive circuitry 152 to an existing circuitry (e.g., a heating circuit for heating seat 160). For instance, such systems that employ a user electrode 151 to heat a seat 160 of, e.g., a vehicle, may be provided with at least inductor L1 as a precaution to filter out any inadvertent temporal components of the DC signal applied to the user electrode 151 for the purposes of heating. Figure 6 schematically represents a modification of the first implementation of Figure 5 where the conductor comprising the capacitor C1 is configured with a suitable connection terminal or connector, schematically shown by terminal 154 in Figure 6, that allows the conductor and user identification circuitry 152 to be coupled to the existing circuitry provided to implement the secondary function (e.g., heating of the seat 160). It should be appreciated that this represents an example of how an existing circuit comprising a user electrode 151 may be retrofit with the user identification drive circuitry 152 but it should be appreciated that any suitable technique / connection mechanism may be employed in order to allow the user identification drive circuitry 152 to be retrofit to an existing circuit comprising a user electrode 151.
Figure 7 schematically represents the connection of the user identification drive circuitry 152 and the secondary drive circuitry 153 to the user electrode 151 according to a second implementation. Figure 7 similarly represents a schematic circuit diagram with components relevant to the principles of the present disclosure being shown. It should be appreciated that the circuit of Figure 7 may include other components and/or connections in practical implementations (for example, various connections to power sources, or to ground, etc.). Figure 7 will broadly be understood from Figure 5 and only the differences are explained herein.
In Figure 7, a switching apparatus 155 is provided between the input to the user electrode 151, the user identification drive circuitry 152 and the secondary drive circuitry 153.
The switching apparatus 155 is arranged so as to selectively couple either of the user identification drive circuitry 152or the secondary drive circuitry 153 to the input of the user electrode 151. In Figure 7 the switching apparatus 155 is a two-state switching apparatus meaning that the switching apparatus 155 has two inputs that are selectively coupled to the single output. However, it should be appreciated that in other implementations, the switching apparatus 155 may have more states, for example a third state that couples neither of the user identification drive circuitry 152 or the secondary drive circuitry 153 to the input of the user electrode 151.
The switching apparatus 155 may be controlled (e.g., by a not shown controller) to be in the first state in which the user identification drive circuitry 152 is coupled to the output of the switching apparatus 155 and hence the input of the user electrode 151, or the second state in which the secondary drive circuitry 153 is coupled to the output of the switching apparatus 155 and hence the input of the user electrode 151. In some implementations, the switching apparatus 155 may be controlled in a time-division multiplex manner. That is, the switching apparatus 155 may be controlled to be in the first state for a first time period, before being switched to the second state for a second time period, and then back to the first state for a subsequent period and so on. Depending on the particular functions implemented, whether the switching apparatus 155 operates in a time division multiplex manner may depend. For example, in the case of the user electrode 151 capable of being controlled to act as a heating element, a user U1 may selectively choose whether the heating function is enabled. When the heating function is enabled, the switching apparatus 155 may be controlled to operate in the time-division multiplex manner as described above to allow both the heating and the user identification functions to be implemented. However, when the heating function is disabled by a user, the switching apparatus 155 may be controlled to remain in the first state (i.e., to couple the user identification drive circuitry 152 to the output of the switching apparatus 155).
Hence, in accordance with the second implementation, the circuitry of the second implementation, and in particular the switching apparatus 155, is provided to allow the user electrode 151 to be selectively driven by the user identification signal or the secondary drive signal. The circuitry of Figure 7 may be particularly suited to implementations where the user identification signal and the secondary drive signal are similar (e.g., both time-varying signals), or where the simultaneous application of both the user identification signal and the secondary drive signal may not be possible or detrimental to overall performance.
Figure 8 schematically represents an alternative arrangement according to a third implementation that allows the user identification signal and the secondary drive signal to be simultaneously applied to the user electrode 151. Figure 8 represents a schematic circuit diagram with components relevant to the principles of the present disclosure being shown. It should be appreciated that the circuit of Figure 8 may include other components and/or connections in practical implementations (for example, various connections to power sources, or to ground, etc.). Figure 8 will broadly be understood from Figure 5 and only the differences are explained herein.
In Figure 8, the separate user identification drive circuitry 152 and secondary drive circuitry 153 of Figures 4 to 7 are integrally formed into integrated unit 156. That is, the user identification drive circuitry 152 and secondary drive circuitry 153 are provided as a single component configured to output a single drive signal to the user electrode 151.
In some implementations, the single drive signal output by the integrated unit 156 includes a component corresponding to the user identification signal and a component corresponding to the secondary drive signal. That is, for example, the single drive signal may be a superposition of the user identification signal and secondary drive signal as generated by the integrated unit 156. In such implementations, the superposition of the user identification signal and secondary drive signal allows for a single drive signal to be applied to the user identification electrode 151 to perform both functions of user identification and the secondary function (e.g., heating). This may be considered similar to the situation as implemented in Figure 5 or 6, for example.
In other implementations, the single drive signal output by the integrated unit 156 may be a signal that is suitably set to perform both functions (i.e., both user identification and the secondary function). For example, if the secondary drive signal is to be a time-varying signal, then the single drive signal output by the integrated unit 156 may be a time-varying signal set with given parameters to perform both the user identification function and the secondary function (such as occupancy detection, for example).
Hence, by providing an integrated unit 156, a single drive signal may be output by the integrated unit 156 capable of performing both the user identification function and the secondary function. Whether the single signal is a superposition of the user identification signal and the secondary drive signal, or whether the single signal is a signal set with properties suitable for performing both functions, in the circuitry of Figure 8 there is no need for a switching apparatus 155 (which may therefore reduce the complexity in terms of control of the circuitry) or any need for protective decoupler circuits (which may therefore reduce the complexity in terms of structure of the circuitry), and thus the circuitry may be considered relatively more simple.
Broadly, a signal generation apparatus 150 for use with a touch-sensitive apparatus 1 has been described, wherein the signal generation apparatus 150 is configured to cause a user or common electrode 151 to function both for the purposes of identifying a user, capacitively coupled to the user electrode 151, when the user, or an object coupled to the user, interacts with a sensing surface of the touch-sensitive apparatus 1, and to perform a secondary function such as heating or occupancy detection. Because a single, common electrode 151 is used to perform several functions, a reduction in the number of electrodes present in the system (e.g., the seat 160) can be reduced, thereby reducing the material costs and reducing material wastage. Moreover, the system can be retrofit to existing systems already employing an electrode in the system (e.g., in the seat 160) without need to provide or form a further electrode in the existing part of the system (e.g., seat 160).
It has generally been described above that the signal generation apparatus 150 is configured to apply either (or both) of the user identification drive signal and the secondary drive signal to the user electrode 151 to perform a user identification function and a secondary function. However, it should be appreciated that, in other implementations, the signal generation apparatus 150 may be configured to perform a third (tertiary) or greater function. For example, the signal generation apparatus 150 may be provided with tertiary drive circuity configured to output a tertiary drive signal to cause the user electrode 151 to perform a tertiary function. For instance, the secondary function may be a heating function (e.g., to heat the seat 160 of the vehicle) while the tertiary function may be an occupancy function (e.g., to determine whether the seat 160 is occupied by a user). The signal generation apparatus 150 may be configured in any suitable way to allow such coupling of the user identification signal, secondary drive signal and tertiary drive signal. For example, the signal generation apparatus 150 may comprise a switching apparatus 155 capable of selectively switching between a first state (in which the user identification signal is provided to the user electrode 151 via the user identification drive circuitry 152), a second state (in which the secondary drive signal is provided to the user electrode 151 via the secondary drive circuitry 153), and a third state (in which the tertiary drive signal is provided to the user electrode 151 via the tertiary drive circuitry).
In some implementations, the signal generation apparatus 150 operates largely independently of the touch-sensitive apparatus 1. That is to say, the signal generation apparatus 150 is not controlled by the controller (e.g., the measurement circuitry 105 or processing circuitry 106). Accordingly, the signal generation apparatus 150 may be provided with its own control circuitry (not shown), which may govern the generation and / or transmission of the various drive signals. However, it should be appreciated that in other implementations, the controller (e.g., the measurement circuitry 105 or processing circuitry 106) may communicate with the signal generation apparatus 150 (e.g., through a wired or wireless communication link) to control operation of the signal generation apparatus 150. In such implementations, generation of the user identification drive signal may be coordinated.
This may either be in the context of providing the user identification drive signal (for example, the user identification signal may be applied to the user electrode 151 only when the touch-sensitive apparatus 1 is operational) or in the context of controlling the properties of the user identifications signal, such as its frequency, so as to be different to the touch-sensing drive signal generated by the touch-sensing drive circuitry 120.
In other implementations, the difference between the user identification signal and the touch-sensing drive signal may be provided by pre-agreed criteria for the touch-sensing apparatus 1 and the signal generation apparatus 150. That is, for example, it may be agreed and standardised to use a particular frequency range for the user identification signal and a particular, non-overlapping frequency range for the touch-sensing drive signal.
While the above has described an implementation in which a single user U1 interacts with the touch-sensitive apparatus 1, it should be appreciated that the principles of the present disclosure can be extended to multiple users interacting with the same touch-sensitive apparatus 1.
Figure 9 is a schematic representation of a system in accordance with the principles of the present disclosure according to an implementation whereby two users, first user U1 and second user U2, interact with the touch-sensitive apparatus 1. Figure 9 will be understood from Figure 4 and like components are identified with similar reference signs. For a detailed discussion on these components, the reader is referred to the above. Only the differences are described herein.
As seen in Figure 9, the system is provided with a second signal generation apparatus 150' comprising a second user electrode 151', second user identification drive circuitry 152', and second secondary drive circuitry 153'. The second user electrode 151' is provided in a second seat 160' in which the second user U2 is shown. The second user electrode 151', second user identification drive circuitry 152', and second secondary drive circuitry 153' are the same or similar to the user electrode 151, user identification drive circuitry 152, and secondary drive circuitry 153 described above and function together in broadly the same way.
In some implementations, the second user identification drive circuitry 152' is configured to output the same user identification signal as output by the user identification drive circuitry 152 (e.g., same form and frequency). In such implementations, when either the first user U1 or second user U2 interact with the touch-sensitive apparatus 1, the controller (e.g., measurement circuitry 105 and processing circuitry 106) is capable of determining that the detected touch / object originates from or belongs to either of the first user U1 or second user U2 based on a detection of a component corresponding to the user identification signal in the received measurements at measurement circuitry 105. However, in such implementations, the controller is unable to distinguish between the first user U1 and the second user U2.
Therefore, in other implementations, the second user identification drive circuitry 152' is configured to apply a second user identification signal to the second user U2 which is different from the first user identification signal applied to the first user U1 by the user identification drive circuitry 152. In this regard, both the first user identification signal and the second user identification signal are time-varying drive signals but may be set such that the frequency or form of the first identification signal and the second identification signal are different (e.g., orthogonal). Accordingly, the first user identification signal may be output having a first frequency while the second user identification signal may be output having a second frequency different from the first frequency.
In such implementations, the processing circuitry 106 is configured to distinguish the measurements obtained by the measurement circuitry 105 to determine whether a given measurement contains a component corresponding to the first user identification signal or the second user identification signal, and therefore to determine whether the detected touch or object belongs to or originates from the first user U1 or the second user U2. The processing circuitry 106 may be provided with information regarding the possible forms / frequencies that are being used to generate the first user identification signal or the second user identification signal so that it is capable of distinguishing the originating location of the first and second user identification signals. The first and second user U1, U2 my simultaneously interact with the touch-sensitive apparatus 1.
Accordingly, the system of Figure 9, which includes a touch-sensitive apparatus 1 and two signal generating apparatus 150, 150' enables the identification and differentiation of touches or objects originating from different users U1, U2. The touch-sensitive system as described above (or the controller thereof) is capable of determining, as a property of the detected touch or object, at least one of: the presence of a touch or object at the sensing surface, a position on the sensing surface of the touch or object, a distance relative to the sensing surface of the touch or object (i.e., in the Z-direction), and an origin of the touch or object (e.g., whether the touch originates from the first user U1 or the second user U2). In this way, two different users U1, U2 are able to interact with the same touch-sensitive apparatus 1, and the processing circuitry 106 is capable of identifying and distinguishing different inputs corresponding to the different users. Depending on the implementation at hand, the processing circuitry 106 may output, or cause the output of, different signals corresponding to the different inputs received from the different users. These signals may be received by a host controller which may cause process the signals accordingly.
Figure 10 is a highly schematic diagram showing the touch-sensitive apparatus 1 coupled to an associated apparatus 602. The associated apparatus 602 generally comprises a computer processor which is capable of running a software application, and may also comprise a display element, such as an LCD screen or the like. In some implementations, the touch sensitive apparatus 1 is integrally formed with the associated apparatus 602, whereas in other implementations the touch-sensitive apparatus 1 is able to be coupled to the associated apparatus 602 e.g., via electrical wiring.
The touch sensitive apparatus 1 functions as an input mechanism for the associated apparatus 602. The processing circuitry 106 outputs a signal 600 indicating the presence, location and/or distance above the sensing surface of a touch corresponding to either the first user U1 and/or second user U2 to the processing circuitry (host controller) of the associated apparatus (not shown). In some applications, signal 600 may simply indicate whether or not a genuine touch has been detected on the touch-sensitive element, whereas in other instances, the signal 600 may indicate one or more positions of the touch or touches on the sensing area, for example as X, Y coordinates (corresponding to the given electrodes), and/or the distance of the touch from the sensing area (i.e., a Z-position). The processing circuitry of the associated apparatus 602 may process the signal 600 in accordance with the application being run on the associated apparatus, e.g., by causing the associated apparatus to perform an action or change the image(s) that is displayed on the display unit. Additionally, the host controller may perform different functions or control based on whether the signal is indicative of an input from the first user U1 or second user U2.
It should be appreciated that while the system of Figure 9 shows two users U1, U2 and two signal generating apparatuses 150, 150', it should be understood that the principles of the present disclosure can be extended to any number of users each having their own corresponding signal generating apparatuses and user electrodes 151.
In the context of Figure 9, Figure 9 may be considered to represent, highly schematically, the layout of a vehicle, such as a car, comprising a driver's seat 160 and a passenger's seat 160'. The touch-sensitive apparatus 1 may form a suitable user interface (UI) in the vehicle. For example, the touch-sensitive apparatus 1 may be located on the dashboard of the vehicle, or on a centre console of the like. The processing circuitry 106 is capable of outputting a signal (e.g., signal 600) indicative of properties of the sensed touch(es), such as the position, the location / distance above the sensing surface, and whether the touch was caused by (originated from) the first user U1 (i.e., the driver of the vehicle) or the second user U2 (i.e., the passenger of the vehicle). These signals are output to a corresponding host controller of the vehicle (corresponding to apparatus 602 in Figure 10), where the host controller of the vehicle performs the relevant functions.
By way of example only, the touch-sensitive apparatus 1 (or the sensing surface thereof) may include a region which corresponds to a particular function. For example, the region may correspond to the function of displaying the current temperature (e.g., as set by a climate control system) inside the vehicle. When a user touches the corresponding region on the sensing surface, a display (which may be part of or separate from the touch-sensitive apparatus) is controlled to display the current temperature. In some vehicles, there is the functionality to set local temperatures in different locations within the vehicle -for example, the temperature of the environment around seat 160 can be set to be different to the temperature of the environment around seat 160'. In the present example, depending on which user (i.e., the first user U1 or second user U2) touches the region of the sensing surface, the touch-sensitive apparatus 1 can cause the display to display the local temperature around the current user's seat 160, 160'. Such an arrangement may generally provide benefits such as more efficient use of the space of the user interface (e.g., in the above example, only a single region is required). Additionally, in some implementations, certain functionality may be blocked depending on where the touch originates. For example, in some implementations, the driver of the vehicle may be prevented from performing certain functions (e.g., inputting of a GPS coordinates or use of other driver navigation systems) when the vehicle is in motion. Conversely, touch inputs received from the passenger may not be blocked. In this case, the decision to block or not block certain inputs may be performed by the host controller, depending on the origin of the detected touch. That is, the touch-sensitive apparatus 1 may still detect the presence of a touch from the driver, but the host controller may decide to take no action on the basis that this touch originates from the driver and the vehicle is in motion. In other examples, the touch-sensitive system may be used for playing games e.g., when the vehicle is stationary and/or if the touch-sensitive apparatus is provided so as to be accessible to the rear passengers. For example, a game such as noughts and crosses may be played by attributing the first user identification signal with e.g., noughts, and the second user identification signal with, e.g., crosses. Based on which user touches, e.g., a display which is overlain by the touch-sensitive element 100, the processing circuitry 106 can be configured to display a nought or a cross at the detected touch location depending on the user who is determined to touch that location. Other potential uses of the touch-sensitive system and / or other functions the touch-sensitive system may be able to perform or cause to be performed are contemplated by this disclosure.
It should be appreciated the described systems are not limited to being implemented in vehicles. In other implementations, the system may be implemented in other scenarios with seating, such as a classroom or lecture theatre, cinema, restaurants, etc. Moreover, as noted above, the system is not limited to uses in which seating is provided; for example, the electrodes 151, 151' may be coupled to floor tiles or the like (for example, surrounding an interactive blackboard / whiteboard).
Figure 11 is a flow diagram showing a method for operating the systems according to aspects of the present disclosure, for example the system of Figure 4.
The method begins at step Si where a user identification signal is generated. For example, as described above, the user identification drive circuitry 152 is controlled to generate a time-varying user identification signal. The time-varying user identification signal is different to the touch-sensing drive signal generated and applied to the touch-sensitive apparatus 1.
At step S2, the user identification signal generated at step S1 is applied to the user electrode 151. As discussed above, when a user, e.g., the first user U1, is provided in proximity of the user electrode 151 while the user electrode 151 is being driven with the user identification signal, the user identification signal couples to the first user U1. Accordingly, when the first user U1 interacts with the touch-sensitive apparatus 1, the user identification signal is further coupled, capacitively, to the touch-sensitive apparatus 1 (and in particular, the electrodes 101, 102 thereof.
The method then proceeds to step S3. At step S3, measurements of the electrode array 101, 102 are obtained by the measurement circuitry 105. These measurements may be obtained periodically, or according to any other schedule. Additionally, the measurements may be indicative of the self-capacitance of individual electrodes and/or of the mutual capacitance between pairs of electrodes, as described above.
It should be appreciated that step S3 is shown as proceeding step S2. However, step S3 may be performed prior to steps 51 or S2. For example, when the touch-sensitive apparatus 1 is active (e.g., it is switched on), the measurement circuitry 105 may repeatedly perform measurements, even in the absence of a user touching the sensing surface and / or generation of the user identification signal. Regardless, the obtained measurements obtained by the measurement circuitry 105 are passed to the processing circuitry 106 for processing. As described above, the processing circuitry 106 is configured to process the obtained measurements from the measurement circuitry 105. When a touch or object is detected, e.g., the difference between a measurement made absent any touch being detected (e.g., in advance) and the current measurement exceed a threshold, the processing circuitry 106 is configured to determine the presence of a touch at the touch-sensitive apparatus 1.
The method proceeds to step S4. At step S4, the measurements of the electrode array 101, 102 obtained by the measurement circuitry 105 which are deemed to correspond to a touch are subsequently analysed to determine whether the measurement(s) have any component corresponding to the user identification signal. Subsequently, the processing circuitry 106 is capable of determining whether the measurement (and hence touch) originated from the first user U1 or not (or in some implementations, also whether the touch originated from the second user U2 or not). The processing circuitry 106 may then output a corresponding signal, such as signal 600, as is described above.
Figure 11 shows the method subsequently proceeding to step S5 after step S4. At step S5, the secondary drive signal is applied to the user electrode 151. This may be in place of the user identification signal applied at step S2 or in addition to. Hence, step S5, although shown after step S4, step S5 may be performed at the same time as or even before step S2.
The secondary drive signal is applied to the user electrode 151 to cause the user electrode 151 to perform the secondary functions (e.g., heating). As will be understood from above, the secondary drive signal may be selectively applied to the user electrode 151, for example when the secondary function is desired by the user.
Hence, more generally, it can be seen that the present disclosure provides an apparatus 150 for use with a touch-sensitive apparatus 1 for identifying a user or object at, or in proximity of, a sensing surface of the touch-sensitive apparatus 1. A common or user electrode 151 is capable of being applied with a user identification signal to perform a function of identifying a user or a secondary drive signal for performing a secondary function. Because the common or user electrode 151 is used to perform both functions, the overall cost and complexity of systems used to deliver both functions can be reduced. Moreover, in some instances, systems that deliver a first function can be retrofit with a system to deliver a second function in addition to the first function.
The above implementations are described in the context of a touch-sensitive apparatus 1 that comprises its own drive circuitry (e.g., touch-sensing drive circuitry 120). In such systems, the touch-sensitive apparatus 1 is capable of determining the presence or absence of a touch, for example, on the basis of measurements received by driving the electrode array 101, 102 with the output of the touch-sensing drive circuitry 120. Thus, the touch-sensitive apparatus 1 is capable of determining the presence of a touch or object at or in the proximity of the sensing surface based on the measurement signals received at the measurement circuitry 105 that occur as a result of the touch-sensing drive signal being applied to the electrode array 101, 102. This is regardless of whether a user U1 is capacitively coupled to the user electrode 151 or not. However, when the user is capacitively coupled to the user electrode 151 as driven by the user identification signal, the touch-sensitive apparatus 1 is configured to determine whether the detected touch belongs to or originates from the user U1 coupled to the user electrode 151 by virtue of detecting a component in the received measurement signals corresponding to the user identification signal.
However, in some implementations, the touch-sensitive apparatus 1 may not comprise its own drive circuitry. In such implementations, instead, the detection of a touch or object at or in the proximity of the sensing surface is performed based on received measurement signals that are generated by the user U1 capacitively coupled to the user electrode 151. In such implementations, in the absence of a touch-sensitive drive signal 113 being applied to the electrode array 101, 102 of the touch-sensitive apparatus 1, the measurements obtained by the measurement circuitry 105 may be essentially zero or consist of any noise that may couple to the electrode array 101, 102. Hence, these measurements are considered to be indicative of the absence of a touch on the electrode array 101, 102 / sensing surface. Conversely, when the user U1 brings their hand / stylus or the like towards the electrode array 101, 102 / sensing surface of the touch-sensitive apparatus 1, the user identification drive signal as applied to the user electrode 151 couples to one or more of the electrodes 101, 102, in a similar manner to as described above. The measurement circuitry 105 therefore obtains a measurement which is indicative of a capacitive coupling at the one or more electrodes of the electrode array 101, 102. This measurement typically will vary from the equivalent measurement made for the given electrode(s) in the absence of a touch (for example, the capacitive signal of a given electrode 101, 102 will increase from the baseline measurement obtained in the absence of a touch).
In such implementations, the processing circuitry 106 operates in a similar manner in that it receives the measurements from the measurement circuitry 105 and is configured to perform processing on the basis of the received measurements. The processing circuitry 106 may determine the presence / absence of a touch and/or the location of a touch and/or whether the touch is a hover touch or a contact touch (as described above). However, the processing circuitry 106 is also configured to determine that, firstly, the touch / object originates from any user coupled to a user electrode 151 (by virtue of the fact that the measurement signal is different from the absent touch measurement) and, secondly, whether the touch belongs to a first user U1 or a second user U2 (or other user) based on the components of the received signal corresponding to a first or second user identification signal (on the assumption that the first or second user identification signals are different as described above).
Thus there has been described an apparatus for use with a touch-sensitive apparatus for identifying a user or object at, or in proximity of, a sensing surface of the touch-sensitive apparatus, the apparatus including: a user electrode; first drive circuitry for generating an identification signal to be applied to the user electrode; and second drive circuitry for generating a second signal to be applied to the user electrode, the second signal being different from the identification signal. In use, the identification signal is capable of capacitively coupling to a user of the apparatus such that when the user, or an object coupled to the user, interacts with the sensing surface of the touch-sensitive apparatus, the identification signal is capable of capacitively coupling to a touch-sensitive electrode of the touch-sensitive apparatus. The second drive circuitry is configured to generate the second signal to cause the user electrode to perform a different function. Also described is a system, a user identification apparatus, a method of operating a touch-sensitive apparatus and use of a user electrode.
Further particular and preferred aspects of the present invention are set out in the accompanying independent and dependent claims. It will be appreciated that features of the dependent claims may be combined with features of the independent claims in combinations other than those explicitly set out in the claims.