Disclosure of Invention
In view of the above, the present application provides a self-capacitance correction method, a touch chip and a touch device, which are used for correcting the self-capacitance value of each signal channel in real time according to the need, thereby ensuring the accuracy of touch operation identification. The technical scheme of the application is as follows:
The application provides a self-capacitance correction method, which is applied to a touch chip, wherein the touch chip is connected with a plurality of signal channels of a touch screen, the signal channels are used for transmitting touch signals and finishing touch detection, the touch chip further comprises a global capacitance unit and a plurality of local capacitance units, the global capacitance unit is connected to the plurality of signal channels, each local capacitance unit is connected to one of the signal channels, the method comprises the steps of obtaining a first self-capacitance value of each signal channel, adjusting the global capacitance unit to the first capacitance value according to all the first self-capacitance values, controlling the adjusted global capacitance unit to offset charges with the self-capacitance of each signal channel, obtaining a second self-capacitance value of each signal channel after the charge offset, adjusting the local capacitance units connected with the corresponding signal channels to the second capacitance value according to the second self-capacitance values, and controlling the self-capacitance of the adjusted local capacitance units and each signal channel to be overlapped or connected with the self-capacitance value of each signal channel to be offset with a target capacitance value.
In an embodiment of the application, the acquiring the first self-capacitance value of each signal channel includes adjusting the global capacitance unit to a preset capacitance value, controlling the adjusted global capacitance unit to perform charge cancellation with the self-capacitance of the signal channel, detecting the voltage value of each signal channel after charge cancellation, and taking the capacitance value corresponding to the voltage value as the first self-capacitance value of each signal channel.
In an embodiment of the application, the global capacitance unit comprises M global capacitances connected in parallel and M switches arranged on a parallel circuit of the global capacitance, wherein the global capacitance unit is adjusted to a first capacitance value according to all the first self capacitance values, and the method comprises the steps of (a) controlling one of the M switches to be conducted, and the rest of the M switches to be disconnected, (b) obtaining a voltage value of each signal channel, (c) determining that a current switch is kept to be conducted when the voltage value of each signal channel is determined to be greater than or equal to a preset voltage value, (d) controlling the current switch to be disconnected when the voltage value of each signal channel is determined to be less than the preset voltage value, and (e) controlling the next switch of the M switches to be conducted until all the M switches are determined to be in an open state and obtaining the capacitance value of the conducted global capacitance as the first capacitance value of the global capacitance unit.
The global capacitance unit comprises M global capacitances connected in parallel and M switches arranged on a parallel circuit of the global capacitance, wherein the global capacitance unit is adjusted to a first capacitance value according to all the first self capacitance values, and the method comprises the steps of (a) controlling one of the M switches to be conducted, disconnecting the rest of the M switches, (b) obtaining a voltage value of each signal channel, (c) screening out a target voltage value which deviates most from a preset voltage value from all the voltage values, (d) determining that a current switch is kept to be conducted when the target voltage value is determined to be larger than the preset voltage value, (e) controlling the current switch to be disconnected when the target voltage value is determined to be smaller than the preset voltage value, f) controlling the next switch of the M switches to be conducted, and executing the step (b) until all the opening and closing states of the M switches are determined, and obtaining the capacitance value of the conducted global capacitance as the first capacitance value of the global capacitance unit.
In an embodiment of the application, the obtaining the second self-capacitance value of each signal channel after charge cancellation includes obtaining a voltage value of the signal channel after charge cancellation, and taking a capacitance value corresponding to the voltage value as the second self-capacitance value.
In an embodiment of the application, the adjusting the local capacitance unit connected with the corresponding signal channel to the second capacitance value according to the second self-capacitance value includes comparing the voltage value with a preset voltage value, determining that the local capacitance unit is used for performing charge superposition when the voltage value is smaller than the preset voltage value, and adjusting the local capacitance unit to the second capacitance value according to a difference value of subtracting the voltage value from the preset voltage value, determining that the local capacitance unit is used for performing charge cancellation when the voltage value is larger than the preset voltage value, and adjusting the local capacitance unit to the second capacitance value according to a difference value of subtracting the preset voltage value from the voltage value, and not adjusting the local capacitance unit when the voltage value is equal to the preset voltage value.
The application provides a touch chip, which is connected with a plurality of signal channels in a touch screen and used for transmitting touch signals and completing touch detection, and further comprises a global capacitance unit, a plurality of local capacitance units, a control unit and a self-correcting unit, wherein the global capacitance unit is used for being connected with the plurality of signal channels, each local capacitance unit is used for being connected with one signal channel, the control unit is used for being connected with each signal channel, each global capacitance unit and each local capacitance unit, the control unit is used for acquiring a first self-capacitance value of each signal channel, adjusting the global capacitance unit to the first capacitance value according to all the first self-capacitance values, and controlling the self-capacitance of the adjusted global capacitance unit to be subjected to charge cancellation with the self-capacitance of each signal channel, acquiring a second self-capacitance value of each signal channel after charge cancellation, adjusting the self-capacitance value of the corresponding signal channel according to the second self-capacitance value, and performing self-correcting on the self-correcting unit to the self-capacitance value of each signal channel after the self-correcting unit is connected with the self-correcting unit to the self-capacitance value of the corresponding signal channel.
In one embodiment of the application, the device further comprises a plurality of self-capacitance detection units, each self-capacitance detection unit is used for being connected with one of the signal channels, or each self-capacitance detection unit is used for being connected with one of the signal channels in a time sharing mode, each self-capacitance detection unit is connected with the control unit, each self-capacitance detection unit is used for detecting the self-capacitance value of the signal channel connected with the self-capacitance detection unit, converting the self-capacitance value into a voltage value and transmitting the voltage value to the control unit, each self-capacitance detection unit comprises a voltage comparator, a feedback capacitor and a reset switch, wherein the negative electrode input end of the voltage comparator is connected with the signal channel, one end of the feedback capacitor is connected with the negative electrode input end of the voltage comparator, the other end of the feedback capacitor is connected with the output end of the voltage comparator, one end of the reset switch is connected with the negative electrode input end of the voltage comparator, and the positive electrode input end of the voltage comparator is connected with a reference voltage.
In an embodiment of the application, the local capacitance unit comprises a local capacitance with an adjustable capacitance value, a first switch group and a second switch group, wherein the first switch group and the second switch group are arranged on a circuit of the local capacitance connected with one signal channel, the first switch group comprises three first switches, the second switch group comprises three second switches, one end of one second switch is connected with the signal channel, the other end of the second switch is grounded, the first end of the local capacitance is connected to the negative electrode input end of the voltage comparator through two first switches and receives capacitance voltage through one second switch, the two first switches are both connected with the signal channel, and the second end of the local capacitance is grounded through one second switch and receives the capacitance voltage through one first switch.
In one embodiment of the application, the circuit further comprises a current mirror unit, wherein the global capacitor unit is connected with each signal channel through the current mirror unit, and the current mirror unit is used for copying the charge of the global capacitor unit to each signal channel.
In an embodiment of the present application, the global capacitor unit includes M global capacitors connected in parallel, and M global capacitor switches disposed on a parallel circuit of the global capacitors.
The application provides a touch device, wherein a plurality of signal channels are arranged in the touch device and are used for transmitting touch signals and completing touch detection, the touch device further comprises a touch chip, the touch chip is connected with the plurality of signal channels in the touch device and further comprises a global capacitance unit, a plurality of local capacitance units, a control unit and a control unit, wherein the global capacitance unit is used for being connected with one signal channel, the control unit is used for being connected with each signal channel, the global capacitance unit and each local capacitance unit, the control unit is used for acquiring a first self-capacitance value of each signal channel, adjusting the global capacitance unit to the first capacitance value according to all the first self-capacitance values, controlling the adjusted self-capacitance of each signal channel to be subjected to charge cancellation, acquiring a second self-capacitance value of each signal channel after the cancellation, and correspondingly adjusting the self-capacitance value of each signal channel to be subjected to charge cancellation, and controlling the self-capacitance value of each self-capacitance unit to be subjected to self-correction according to the second self-capacitance value of each signal channel and the self-correction unit to be subjected to the self-capacitance value of each signal channel, and the self-correction unit is connected with the self-capacitance value of each signal channel to be subjected to self-correction.
The technical scheme provided by the application has the advantages that the global capacitance units are arranged to be connected to each signal channel of the touch screen, and each signal channel is provided with one local capacitance unit, when the self-capacitance correction is required to be carried out on the signal channels, the global capacitance units are firstly adjusted to enable the self-capacitance values of all the signal channels to approach to the target reference capacitance value, then the local capacitance units of each signal channel are adjusted, finally, after the global capacitance units and the local capacitance units are subjected to superposition or offset of electric charge amounts, the self-capacitance values of the signal channels connected with the global capacitance units are corrected to the target reference capacitance value, so that the function of real-time self-capacitance value correction of the signal channels is realized, namely, when the self-capacitance values of the signal channels change due to long-term use of the touch screen, the self-capacitance values of the signal channels can be corrected in time, and the accuracy of touch operation identification is ensured.
Detailed Description
It should be noted that, in the embodiments of the present application, "at least one" means one or more, and "a plurality" means two or more. "and/or" describes an association relationship of associated objects, meaning that there may be three relationships, e.g., A and/or B may mean that A alone exists, while A and B together exist, and B alone exists, where A, B may be singular or plural. The terms "first," "second," "third," "fourth" and the like in the description and in the claims and drawings, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order.
It should be further noted that, in the method disclosed in the embodiment of the present application or the method shown in the flowchart, one or more steps for implementing the method are included, and the execution order of the steps may be interchanged with each other, where some steps may be deleted without departing from the scope of the claims.
Currently, with the continuous progress of touch screen technology, the man-machine interaction function of most electronic products in the market is realized by using a touch screen, especially various electronic terminal products, such as mobile phones, tablet computers, notebooks, electronic books, and other electronic terminals, and most of the electronic terminals adopt capacitive touch screens to perform man-machine interaction.
In addition, the flexible touch screen has the obvious advantages of light and thin volume, low power consumption, bending and the like, so that more and more manufacturers provide more excellent product experience for users, and most of manufactured electronic terminal products adopt the flexible touch screen. The packaging layer between the touch electrode layer of the flexible touch screen and the cathode layer of the light emitting diode is generally of a thin film flexible structure, so that compared with the traditional externally hung touch screen, the flexible touch screen has the advantages that the distance between the touch electrode layer and the cathode layer is relatively close, and the self capacitance value of a signal channel formed by the touch electrodes in the touch electrode layer is relatively large. In the process that the flexible touch screen detects the change of the self capacitance value of the signal channel and further detects touch operation, a relatively large correction capacitor (corresponding to the base reduction capacitor in the background technology) is needed to compensate the self capacitance value of the signal channel, so that the self capacitance value of the signal channel of the flexible touch screen reaches the reference capacitance value.
In the related art, in order to make the self capacitance value of each signal channel of the touch screen approach to the reference capacitance value, a correction capacitor with a larger capacitance value is used to connect to each signal channel of the touch screen. In addition, since the self capacitance value of each signal channel is different, the manufacturer of the touch screen finds a correction capacitance value through testing before the touch screen leaves the factory, and then stores the correction capacitance value in a chip of the touch screen, and when the self capacitance value of each signal channel is counteracted by the correction capacitance of the correction capacitance value, the self capacitance value of each signal channel can only approach to the reference capacitance value. Since the correction capacitance cannot be adjusted any more in the following process, when the self-capacitance value of the signal channel changes due to the change of the use environment of the touch screen, the corrected self-capacitance value of the signal channel can deviate from the reference capacitance value more and more, so that the accuracy of the touch screen on touch operation detection is affected.
The embodiment of the application provides a self-capacitance correction method which is applied to a touch chip, so that the base-reduced capacitance value of each signal channel of the touch screen can be corrected in real time according to the requirement of the touch chip, when the self-capacitance value of the signal channel changes due to the change of the use environment of the touch screen, the self-capacitance value after accurate correction can still be obtained, and the self-capacitance value after correction is equal to or approaches to a reference capacitance value, thereby ensuring the accuracy of touch operation identification.
Fig. 1 is a schematic structural diagram of a touch screen according to an embodiment of the present application. The touch screen 100 includes a plurality of signal channels 110, a global capacitive unit 120, and a plurality of local capacitive units 130, wherein the global capacitive unit 120 is connected to each signal channel 110, and each local capacitive unit 130 is connected to one of the signal channels 110.
The signal channel 110 may be a single touch electrode, or may be formed by connecting a plurality of touch electrodes. The signal channel 110 is used for transmitting a touch signal and then sensing the touch signal, and the touch point of the conductor on the touch screen 100 changes the self-capacitance value of the coupling node. The touch screen 100 obtains the charge information generated by the self-capacitance change through the analog circuit, converts the charge information into a digital signal, and transmits the digital signal to the microprocessor to detect the self-capacitance of the touch point, thereby calculating the coordinates of the touch point on the touch screen 100. The touch signal comprises a carrier signal with a preset frequency.
In the embodiment of the present application, the global capacitance unit 120 and the local capacitance unit 130 are adjustable capacitance values, and the capacitance value of the global capacitance unit 120 may be much larger than the capacitance value of the local capacitance unit 130.
Fig. 2 is a schematic flow chart of a self-capacitance correction method according to an embodiment of the application. The self-capacitance correction method is applied to the touch screen shown in fig. 1. The self-capacitance correction method comprises the following steps:
step S21, a first self-capacitance value of each signal channel is obtained.
In the embodiment of the application, when the touch screen needs to correct the self-capacitance value of each signal channel, the first self-capacitance value of each signal channel can be acquired in a detection mode. Because each signal channel is connected to the global capacitance unit and each signal channel is connected to one of the local capacitance units, the touch screen can firstly control to disconnect the global capacitance unit from the signal channel and disconnect the local capacitance unit from the signal channel, and then acquire the first self capacitance value so as to ensure the accuracy of the first self capacitance value.
The touch screen further comprises a control unit, wherein the control unit is used for controlling the first switch unit or the second switch unit to be disconnected by sending a control instruction to the first switch unit and the second switch unit.
Or because the global capacitance unit and the local capacitance unit are adjustable in capacitance value, the control unit is directly connected to the global capacitance unit and the local capacitance unit. Before the first self-capacitance value of each signal channel is obtained, the global capacitance unit and the local capacitance unit are initialized to the initialization values by sending control instructions to the global capacitance unit and the local capacitance unit, then the current self-capacitance value of each signal channel is obtained, and finally the first self-capacitance value is obtained according to the current self-capacitance value and the initialization values.
Step S22, adjusting the global capacitance unit to the first capacitance value according to all the first self capacitance values.
In the embodiment of the application, after the first self-capacitance value of each signal channel of the touch screen is obtained, the control unit of the touch screen firstly adjusts the global capacitance unit according to the first self-capacitance value to enable the global capacitance unit to reach the first capacitance value. The global capacitance unit is mainly used for enabling the self capacitance value of the signal channel to approach to the reference capacitance value through charge cancellation, so that the reference capacitance value can be considered besides the first self capacitance value when the global capacitance unit is adjusted.
For example, when the reference capacitance value is 0, the control unit of the touch screen may calculate an average value according to all the first self-capacitance values, and adjust the first capacitance value of the global capacitance unit to be the average capacitance value. Or screening out the intermediate value of the first self-capacitance value from all the first self-capacitance values, and adjusting the first capacitance value of the global capacitance unit to be the intermediate value. Or screening out the minimum value of the first self-capacitance values from all the first self-capacitance values, and adjusting the first self-capacitance value of the global capacitance unit to be the minimum value. Or screening out the maximum value of the first self-capacitance value from all the first self-capacitance values, and adjusting the first self-capacitance value of the global capacitance unit to be the maximum value.
Similarly, when the reference capacitance value is not 0, the reference capacitance value is subtracted from each first self-capacitance value to obtain a plurality of capacitance difference values, and then the average value calculation is performed from the plurality of capacitance difference values, and the intermediate value, the minimum value, the maximum value, and the like are screened, so as to finally obtain the first capacitance value of the global capacitance unit.
And S23, controlling the adjusted global capacitance unit and the self capacitance of each signal channel to perform charge cancellation.
In the embodiment of the application, the self capacitance value of the signal channel can be close to the reference capacitance value by charge cancellation by utilizing the adjusted global capacitance unit. When the touch screen performs touch detection, a carrier signal is sent in the signal channel, and when the carrier signal is transmitted in the signal channel, the self capacitance of the signal channel generates charges. And when the signal channel transmits the carrier signal, the signal channel transmits the opposite-phase signal to the global capacitance unit, so that the global capacitance unit can generate opposite-phase charge, and the opposite-phase charge can offset the charge of the signal channel according to charge conservation, thereby enabling the self capacitance value of the signal channel to approach to the reference capacitance value.
Wherein, the phase of the above-mentioned inverted signal is opposite to the carrier signal, the amplitude of the inverted signal can be equal to the carrier signal. The amount of inverted charge generated by the global capacitive element is related to its first capacitance value. One end of the global capacitor unit is connected with the signal channel, and the other end is used for inputting an inverted signal when the charges are counteracted.
Step S24, obtaining a second self-capacitance value of each signal channel after charge cancellation.
In the embodiment of the application, after charge cancellation is performed on each signal channel by using the adjusted global capacitance unit, the second self-capacitance value of each signal channel is detected again. Wherein the second self-capacitance value of each signal path may be equal to the reference capacitance value, or less than the reference capacitance value, or greater than the reference capacitance value.
In the example of step S22, the reference capacitance value is not 0. If the first capacitance value takes an average value or an intermediate value of a plurality of capacitance differences (the capacitance difference is obtained by subtracting the reference capacitance value from each first self capacitance value), the plurality of second self capacitance values are equal to the reference capacitance value, or are smaller than the reference capacitance value, or are larger than the reference capacitance value.
If the first capacitance value takes the minimum value of the capacitance differences, the second self-capacitance values are equal to or greater than the reference capacitance value.
If the first capacitance value takes the maximum value of the capacitance differences, the second self-capacitance values are equal to or smaller than the reference capacitance value.
And S25, adjusting the local capacitance units connected with the corresponding signal channels to the second capacitance values according to the second self-capacitance values.
In the embodiment of the application, the main function of the local capacitance unit is to further adjust the self capacitance value of the corresponding channel, so that the self capacitance value of the signal channel is equal to the target reference capacitance value, or the signal channel is further close to the reference capacitance value.
And S26, controlling the adjusted local capacitance units to carry out charge superposition or cancellation with the self capacitance of each signal channel, and correcting the self capacitance value of the signal channel connected with the local capacitance units to a target reference capacitance value.
In the embodiment of the application, the self-capacitance value of the current signal channel can be judged to be equal to the target reference capacitance value, or smaller than the target reference capacitance value, or larger than the target reference capacitance value through the second self-capacitance value. When the second self-capacitance value of the current signal channel is equal to the target reference capacitance value, that is, the self-capacitance value of the current signal channel is not required to be corrected, the corresponding local capacitance unit can be controlled to be disconnected, or the corresponding local capacitance unit is controlled to be invalid, or the capacitance value of the corresponding local capacitance unit is controlled to be 0.
When the second self capacitance value of the current signal channel is smaller than the target reference capacitance value, the self capacitance value of the current signal channel is required to be corrected to be increased to the target reference capacitance value, at the moment, the difference value of the second capacitance value minus the target reference capacitance value is calculated, the corresponding local capacitance unit is adjusted by the difference value, and a normal phase signal with the same phase of the carrier signal is transmitted to the local capacitance unit during correction.
When the second self capacitance value of the current signal channel is larger than the target reference capacitance value, the self capacitance value of the current signal channel is required to be corrected to be reduced to the target reference capacitance value, at the moment, the difference value of the target reference capacitance value minus the second capacitance value is calculated, the corresponding local capacitance unit is adjusted by the difference value, and an inversion signal opposite to the carrier signal is transmitted to the local capacitance unit during correction.
In the embodiment of the application, the global capacitance unit is arranged to be connected to each signal channel of the touch screen, and each signal channel is provided with the local capacitance unit, when the self-capacitance correction is required to be carried out on the signal channels, the global capacitance unit is firstly adjusted to enable the self-capacitance values of all the signal channels to approach to the target reference capacitance value, then the local capacitance unit of each signal channel is adjusted, finally, after the global capacitance unit and the local capacitance unit are subjected to superposition or offset of electric charge amounts, the self-capacitance value of the signal channel connected with the global capacitance unit is corrected to the target reference capacitance value, so that the function of real-time self-capacitance value correction of the signal channels is realized, namely, when the self-capacitance value of the signal channels is changed due to the change of the use environment of the touch screen, the self-capacitance value of the signal channels can be corrected in real time, and the accuracy of touch operation identification is ensured.
Referring to fig. 3, a flowchart of a first self-capacitance value obtaining method according to an embodiment of the present application is shown, and the method is one implementation of the step S21, and specifically includes the following steps:
Step S31, adjusting the global capacitance unit to a preset capacitance value.
In the embodiment of the application, when the signal channel transmits the touch signal, the voltage value of the signal channel can be detected, and the voltage value is converted into the first self-capacitance value, or the voltage value is directly used as the first self-capacitance value. In order to adjust the signal channel to the target reference capacitance value faster, the global capacitance unit may be adjusted to a preset capacitance value to perform charge cancellation with the signal channel. The preset capacitance value may be, for example, a half capacitance value in the adjustable range of the global capacitance unit, or when the global capacitance unit is a multi-bit switch capacitance, the switch of the highest bit number may be controlled to be closed, so that the switch capacitance corresponding to the highest bit number is used as the preset capacitance value.
And S32, controlling the adjusted global capacitance unit to offset the charge with the self capacitance of the signal channel.
In the embodiment of the application, the charge cancellation is performed between the global capacitance unit and the self capacitance of the signal channel by transmitting the positive phase signal to the signal channel and transmitting the inverse signal to the global capacitance unit. The positive signal and the negative signal have opposite phases, and the positive signal may be a touch signal of a touch screen, or a carrier signal generated by a touch screen control unit and used for detecting self capacitance of a signal channel.
And step S33, detecting the voltage value of each signal channel after charge cancellation.
And step S34, taking the capacitance value corresponding to the voltage value as a first self-capacitance value of each signal channel.
In the embodiment of the application, the global capacitance is adjusted to the preset capacitance value in advance, the voltage value of each signal channel is obtained, the corresponding capacitance value is converted according to the voltage value and is used as the first self capacitance value of the signal channel, and the frequency of subsequent adjustment of the global capacitance can be reduced, so that the speed of adjusting the self capacitance value of the signal channel to the target reference capacitance value is further improved.
Referring to fig. 4, a flow chart of a global capacitor unit adjustment method according to an embodiment of the present application is provided, wherein the method is one implementation of the step S22, and the global capacitor unit in the method includes M global capacitors connected in parallel and M switches disposed on a parallel circuit of the global capacitors. The method specifically comprises the following steps:
And S41, controlling one of the M switches to be on, and controlling the rest of the M switches to be off.
In the embodiment of the application, the M global capacitors may include global capacitors with the same capacitance value and global capacitors with different capacitance values, and the global capacitor units are adjusted to the corresponding capacitance values by controlling the connection or disconnection of any switch in the M switches so as to control any global capacitor to be connected in parallel.
Before the voltage value of the signal channel is obtained and the switch control of the global capacitor is performed according to the voltage value, one of the switches can be controlled to be turned on first so as to adjust the global capacitor unit to an initial capacitance value. For example, the switch related to the global capacitor with the largest capacitance value in the global capacitors can be controlled to be turned on, so that the global capacitor units are adjusted to the corresponding capacitance values.
And S42, acquiring the voltage value of each signal channel.
And step S43, when the voltage value of each signal channel is larger than or equal to a preset voltage value, the current switch is determined to be kept on.
In the embodiment of the application, the preset voltage value, that is, the voltage value corresponding to the signal channel after being adjusted to the target reference capacitance value, therefore, when the voltage value of each signal channel is determined to be larger than the preset voltage value, the capacitance value of the current global capacitance unit is smaller, that is, the capacitance value of the current switch needs to be further increased, that is, the current switch needs to be determined to be kept on, and then other switches need to be turned on to increase the capacitance value.
And S44, when the voltage value of each signal channel is smaller than the preset voltage value, the current switch is controlled to be turned off.
In the embodiment of the application, when the voltage value of each signal channel is smaller than the preset voltage value, the capacitance value of the global capacitance unit for switching on the current switch is larger, and the comparison is performed after other global capacitances are required to be selected to be connected in parallel, namely the current switch is required to be disconnected, and then the other switches are required to be switched on to adjust the capacitance value.
Step S45, controlling the next switch of the M switches to be conducted, and executing step S42 until all the open and close states of the M switches are determined, and obtaining the capacitance value of the conducted global capacitor as the first capacitance value of the global capacitor unit.
In the embodiment of the invention, the working states of the M switches can be determined to be on or off by controlling the next switch to be turned on and then returning to the step S42, so that the first capacitance value of the global capacitance unit is determined, and when the global capacitance unit with the first capacitance value performs charge offset on all signal channels, the self capacitance values of most signal channels are enabled to approach to the target reference capacitance value.
Referring to fig. 5, a flow chart of a global capacitor unit adjustment method according to an embodiment of the present application is provided, wherein the method is another implementation manner of the step S22, and the global capacitor unit in the method includes M global capacitors connected in parallel and M switches disposed on a parallel circuit of the global capacitors. The method specifically comprises the following steps:
And S51, controlling one of the M switches to be on, and controlling the rest of the M switches to be off.
Step S52, the voltage value of each signal channel is obtained.
Step S53, screening out the target voltage value which deviates from the preset voltage value the most from all the voltage values.
In the embodiment of the application, after the current switch is controlled to be turned on and charge cancellation is performed on each signal channel by using the global capacitance unit with the current corresponding capacitance value, the obtained voltage value of each signal channel also comprises the conditions of being larger than a preset voltage value, equal to the preset voltage value and smaller than the preset voltage value. When all three conditions are included, a target voltage value deviating from a preset voltage value to the maximum is required to be obtained to determine the on-off state of the current switch. Wherein the deviation is the value of the phase difference between the voltage value and the preset voltage value.
And S54, when the target voltage value is determined to be larger than the preset voltage value, the current switch is determined to be kept on.
In the embodiment of the application, when the target voltage value is determined to be larger than the preset voltage value, namely the self capacitance value of the existing signal channel is larger, the capacitance value of the current global capacitance unit is smaller, and the self capacitance value of the signal unit is far from the target reference capacitance value after charge cancellation is carried out, so that the current switch needs to be determined to be kept on, and then other switches are further conducted to increase the capacitance value.
And S55, when the target voltage value is smaller than the preset voltage value, the current switch is controlled to be turned off.
In the embodiment of the application, when the target voltage value is determined to be smaller than the preset voltage value, namely the self capacitance value of the existing signal channel is smaller, and the capacitance value of the current global capacitance unit is larger, so that the self capacitance value of the signal unit is far from the target reference capacitance value after charge cancellation is carried out, therefore, western medicines open the current switch, and then select the switch corresponding to the global capacitance with smaller capacitance value to control the closing.
Step S56, the next switch of the M switches is controlled to be conducted, and step S52 is executed until all the open and close states of the M switches are determined, and the capacitance value of the conducted global capacitor is obtained as the first capacitance value of the global capacitor unit.
In the embodiment of the invention, the working states of the M switches can be determined to be on or off by controlling the next switch to be turned on and then returning to the step S52, so that the first capacitance value of the global capacitance unit is determined, and when the global capacitance unit with the first capacitance value performs charge offset on all signal channels, the self capacitance values of most signal channels are enabled to approach to the target reference capacitance value.
Referring to fig. 6, a flow chart of a method for adjusting a local capacitance unit according to an embodiment of the present application is shown, wherein the method is one implementation of the step S24 and the step S25, and specifically includes the following steps:
Step S61, the voltage value of the signal channel after charge cancellation is obtained.
And step S62, taking the capacitance value corresponding to the voltage value as a second self-capacitance value.
And step S63, comparing the voltage value with a preset voltage value.
And S64, when the voltage value is smaller than the preset voltage value, determining that the local capacitance unit is used for carrying out charge superposition, and adjusting the local capacitance unit to a second capacitance value according to the difference value of the preset voltage value minus the voltage value.
In the embodiment of the application, after the first capacitance value of the global capacitance unit is determined, the second capacitance value of the local capacitance unit corresponding to each signal channel is adjusted. The global capacitance unit is multiplexed to the plurality of signal channels, so after the adjusted global capacitance unit with the first capacitance value and each signal channel perform charge offset, the second self capacitance value of each signal channel may be different, and may be greater than the target reference capacitance value, less than the target reference capacitance value, and equal to the target reference capacitance value.
For a signal channel smaller than the target reference capacitance value, that is, when the voltage value of the signal channel is smaller than the preset voltage value, it is determined that the second self-capacitance value of the signal channel is smaller than the target reference capacitance value, and then the self-capacitance value of the current signal channel needs to be increased by performing charge superposition through the corresponding local capacitance unit. The second capacitance value is a difference obtained by subtracting a second self capacitance value from the target reference capacitance value. The second capacitance value can be obtained by the above-mentioned difference conversion, or the local capacitance unit can be controlled to change its capacitance value from small to large, and finally be adjusted to the second capacitance value.
Since the local capacitance unit is for charge superposition to increase the self capacitance value of the current signal path, the signal input at the time of correction is a signal having the same phase as the positive phase signal of the signal path.
Step S65, when the voltage value is larger than the preset voltage value, determining that the local capacitance unit is used for charge cancellation, and adjusting the local capacitance unit to the second capacitance value according to the difference value of the voltage value minus the preset voltage value.
In the embodiment of the application, for the signal channel with the value larger than the target reference capacitance, that is, when the voltage value of the signal channel is larger than the preset voltage, the second self-capacitance value of the signal channel is determined to be larger than the target reference voltage value, and then the self-capacitance value of the current signal channel is required to be reduced by charge offset through the corresponding local capacitance. The second capacitance value is a difference obtained by subtracting the target reference voltage value from the second self-capacitance value. The second capacitance value can be obtained by the above-mentioned difference conversion, or the local capacitance unit can be controlled to change its capacitance value from small to large, and finally be adjusted to the second capacitance value.
Since the local capacitance unit is for charge cancellation to reduce the self capacitance value of the current signal path, the signal input at the time of correction is an inverted signal opposite to the phase of the positive signal of the signal path.
Step S66, when the voltage value is equal to the preset voltage value, the local capacitance unit is not adjusted.
In the embodiment of the present application, if the voltage value of the current signal channel is equal to the preset voltage value, it is indicated that the self-capacitance value of the signal channel is already equal to the target reference capacitance value after the charge of the global capacitance unit is cancelled, so that there is no need to adjust the local capacitance unit connected with the self-capacitance value.
Fig. 7 is a schematic structural diagram of a touch chip connected to a signal channel according to an embodiment of the present application.
The touch chip is connected with a plurality of signal channels 710 in the touch screen, the signal channels 710 are used for transmitting touch signals and completing touch detection, and the touch chip further comprises:
And a global capacitance unit 720, the global capacitance unit 720 being connected to the plurality of signal channels 710.
A plurality of local capacitance units 730, each local capacitance unit 730 being connected to one of the signal paths 710.
Control unit 740, control unit 740 is connected to each signal path 710, global capacitance, and each local capacitance.
The control unit 740 is configured to obtain a first self-capacitance value of each signal channel 710, adjust the global capacitance unit 720 to the first capacitance value according to all the first self-capacitance values, control the adjusted global capacitance unit 720 to perform charge cancellation with the self-capacitance of each signal channel 710, obtain a second self-capacitance value of each signal channel 710 after charge cancellation, adjust the local capacitance unit 730 connected to the corresponding signal channel 710 to the second capacitance value according to the second self-capacitance value, and control the adjusted local capacitance unit 730 to perform charge superposition or cancellation with the self-capacitance of each signal channel 710, thereby correcting the self-capacitance value of the signal channel 710 connected thereto to the target reference capacitance value.
As shown in fig. 8, the global capacitance unit 720 includes M global capacitances 721 connected in parallel, and M global capacitance switches 722 disposed on parallel circuits of the global capacitances. The control and adjustment process of each global capacitor 721 and each global capacitor switch 722 in the global capacitor unit 720 can be described with reference to fig. 4,5 and related contents.
Fig. 9 is a schematic structural diagram of another touch chip connected to a signal channel according to an embodiment of the present application.
The touch chip of fig. 9 is different from the touch chip of fig. 7 in that the touch chip further includes:
Each self-capacitance detecting unit 750 is connected to one of the signal channels 710, or each self-capacitance detecting unit 750 is connected to one of the signal channels in a time-sharing manner and each self-capacitance detecting unit 750 is connected to the control unit 740.
The self-capacitance detecting unit 750 is configured to detect a self-capacitance value of the signal channel 710 connected thereto, convert the self-capacitance value into a predetermined type of electrical parameter, and transmit the predetermined type of electrical parameter to the control unit 740.
In the embodiment of the present application, when the signal channel 710 is used for transmitting a touch signal, the self-capacitance detection unit 750 can detect a corresponding self-capacitance value and output a corresponding preset type point parameter. When the signal path 710 is connected to the global capacitance unit 720 and the local capacitance unit 730 to correct the self-capacitance value, the self-capacitance detecting unit 750 may detect the corrected self-capacitance value and output a corresponding preset type point parameter.
The self-capacitance detecting unit 750 includes a CA self-capacitance detecting circuit, and the predetermined type of electrical parameter output by the CA self-capacitance detecting circuit is a voltage value. Fig. 10 is a circuit diagram of a CA self-capacitance detection circuit according to an embodiment of the present application.
The CA self-capacitance detection circuit comprises a voltage comparator 751, a feedback capacitance cf and a reset switch rst. Wherein the negative input of the voltage comparator 751 is connected to the signal path 710. One end of the feedback capacitor cf is connected with the negative input end of the voltage comparator 751, and the other end of the feedback capacitor cf is connected with the output end of the voltage comparator 751. One end of the reset switch rst is connected to the negative input terminal of the voltage comparator 751, and the other end is connected to the output terminal of the voltage comparator 751. The positive input of the voltage comparator 751 is connected to a reference voltage VREF.
The on-off control of the switch rst corresponds to a touch signal transmitted on the signal channel, for example, when the touch signal transmitted on the signal channel is a square wave, the switch rst is turned on at a high level, and the switch rst is turned off at a low level. After the self-capacitance correction process of all the signal channels 710 is completed, the CA self-capacitance detection circuit is further configured to detect a touch operation, that is, when detecting the touch operation, the CA self-capacitance detection circuit obtains a voltage value signal and transmits the voltage value signal to a computing unit (not shown) in the touch chip for computing the touch coordinates, so as to compute the corresponding touch coordinates according to the voltage value signal.
Please refer to fig. 11, which is a circuit diagram of a local capacitor unit according to an embodiment of the present application. The local capacitance unit 730 includes a local capacitance Cb with an adjustable capacitance, a first switch set, and a second switch set, where the first switch set and the second switch set are disposed on a circuit where the local capacitance is connected to one of the signal channels.
As shown in fig. 11, the first switch group includes three first switches Φ1, and the second switch group includes three second switches Φ2. One end of one of the second switches Φ2 is connected to the signal path 710, and the other end is grounded. The first terminal of the partial capacitor Cb is connected to the negative input terminal of the voltage comparator 751 through two first switches Φ1, and receives the capacitor voltage VDD through a second switch Φ2, where the two first switches Φ1 are connected to the signal path 710. The second terminal of the partial capacitor Cb is grounded through one of the second switches Φ2 and receives the capacitor voltage VDD through one of the first switches Φ1.
Referring to fig. 12, a control timing diagram of a first switch set, a second switch set and a reset switch according to an embodiment of the application is shown. The control timing diagram includes a level control signal transmitted to the reset switch rst, a level control signal transmitted to the plurality of first switches Φ1, a level control signal transmitted to the plurality of second switches Φ2, and a voltage signal ca_out at an output terminal of the voltage comparator 751. The high level section of the level control signal controls the switch to be closed, and the low level end of the level control signal controls the switch to be closed.
The level control signal controls the reset switch rst, the first switches Φ1 and the second switches Φ2 to cooperate, so that the self-capacitance detecting unit 750 can output the current self-capacitance value of the signal channel 710 after adding the local capacitance unit 730. When the reset switch rst, the second switches Φ2 are closed, and the first switches Φ1 are opened, the self-capacitance detecting unit 750 is in a reset state, the charge on the feedback capacitor cf of the signal channel 710 is discharged, the first end of the local capacitor Cb is charged by the capacitor voltage VDD, and the second end is grounded. When the reset switch rst, the plurality of second switches Φ2 are turned off, and the plurality of first switches Φ1 are turned on, the self-capacitance detecting unit 750 charges the signal channel 710 to the reference voltage VREF, the second end of the local capacitance Cb receives the capacitance voltage VDD, and the first end is connected to the negative input end of the self-capacitance detecting unit 750, so that the capacitance value of the local capacitance Cb is overlapped with the capacitance value of the signal channel 710, and the self-capacitance detecting unit 750 outputs the corresponding voltage signal ca_out.
Fig. 13 is a schematic structural diagram of a third touch chip connected to a signal channel according to an embodiment of the present application.
The touch chip of fig. 13 is different from the touch chip of fig. 9 in that the touch chip further includes:
The current mirror unit 760, the global capacitance unit 720 is connected to each signal channel 710 through the current mirror unit 760, and the current mirror unit 760 is used to copy the charge of the global capacitance unit 720 to each signal channel 710.
In the embodiment of the present application, multiplexing of one global capacitance unit 720 to each signal channel 710 can be achieved through the current mirror unit 760, so that the consumption area of the integrated circuit of the touch chip can be reduced.
Referring to fig. 14, fig. 14 is a circuit diagram of a global capacitor unit and a self-capacitance detection unit according to an embodiment of the present application.
The output terminals of the current mirror unit 760 are connected to the negative input terminal of the voltage comparator of a self-capacitance detection unit 750 through a first switch Φ1 and a corresponding arrangement.
The embodiment of the application also provides a touch device, which is internally provided with a plurality of signal channels, wherein the signal channels are used for transmitting touch signals and completing touch detection, the touch device further comprises a touch chip, the touch chip is connected with the plurality of signal channels in the touch device, the touch chip further comprises a global capacitance unit, the global capacitance unit is used for being connected with the plurality of signal channels, each local capacitance unit is used for being connected with one signal channel, a control unit is used for being connected with each signal channel, the global capacitance unit and each local capacitance unit, the control unit is used for acquiring a first self capacitance value of each signal channel, adjusting the global capacitance unit to the first capacitance value according to all the first self capacitance values, controlling the adjusted global capacitance unit to offset charges with the self capacitance of each signal channel, acquiring a second self capacitance value of each signal channel after charge offset, adjusting the local capacitance unit connected with the corresponding signal channel to the second capacitance value according to the second self capacitance value, and controlling the adjusted local capacitance unit to be overlapped with the self capacitance value of each signal channel or the self capacitance value of each signal channel to be connected with a reference capacitance value.
The embodiment of the application also provides a computer storage medium, which stores a computer program, and when the computer program is executed by a processor, the computer program causes the processor to execute the self-capacitance correction method. In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, produces a flow or function in accordance with embodiments of the present application, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus. The computer instructions may be stored in or transmitted across a computer storage medium. The computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by a wired (e.g., coaxial cable, fiber optic, digital subscriber line (Digital Subscriber Line, DSL)), or wireless (e.g., infrared, wireless, microwave, etc.). The computer storage media may be any available media that can be accessed by a computer or a data storage device such as a server, data center, or the like that contains an integration of one or more available media. The usable medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a magnetic tape), an optical medium (e.g., a digital versatile disk (DIGITAL VERSATILE DISC, DVD)), or a semiconductor medium (e.g., a Solid State Disk (SSD)), or the like.
Those skilled in the art will appreciate that implementing all or part of the above-described embodiment methods may be accomplished by way of a computer program, which may be stored in a computer-readable storage medium, instructing relevant hardware, and which, when executed, may comprise the embodiment methods as described above. The storage medium includes various media capable of storing program codes such as ROM, RAM, magnetic disk or optical disk. The technical features in the present examples and embodiments may be arbitrarily combined without conflict.
The above-described embodiments are merely illustrative of the preferred embodiments of the present application and are not intended to limit the scope of the present application, and various modifications and improvements made by those skilled in the art to the technical solution of the present application should fall within the scope of protection defined by the claims of the present application without departing from the design spirit of the present application.