Vieng SystemThis invention relates to a vehicle rearward Viewing system.
Rear-view mirrors for vehicles are well known image reflectnrs which comprise a pivoted mirror and holder mounted on a suitable anchorage point in front of the vehicle's driver position, tie molntfng being either internal or external to the vehicle according to whether the desired and feasible field of 7view to be covered is the immediate rearward space from the centre outward on a wide angle basis, or along the left or righthand sides of the vehicle. Thus internal mirrors are normally mounted overhead centrally relative to the width of the vehicle so as to focus through the rear window, while external wig mirrors are mounted on the left or righthand sides of the vehicle. By means of the pivot the angle of inclination of such mirrors is adjustable to obtain the optimum Triew.
Facing rearward of the driver, such mirror systems afford the driver a mirror-image view of the space to the rear of the vehicle, the image being converted by the mirror to a correct and natural right-Way-ronnd view so that objects to the rear left, centre and right are seen to the left, centre and right respectively. This is an important advantage of the mirror.
A problem with such mirror systems, however, is the need for the mirror to be unobstructed by any solid or opaque barrier withit the mirror's field of view. The length and type of the vehicle also influences the size and placement of the mirror.
Many vehicles have no rear window for the driver to see through. Lorries, box vans, and toing vehicles, for example, all have barriers or a load interposed between the space to the immediate rear of fhe vehicle and the driver, and this have to rely on wing mirrors, often mounted on extended mounting arms. The drivers of such vehicles are prevented from seeing immediatelv to the rear of the vehicle and this ca cause difficulties when reversing.
Most vehicles have a dashboard constructed immediately behind the windscreen. The dashboard provides a ledge giving limited shelf space and the means for incorporating a range of visual and control inntrllnenttion of compact size.
An object of the present invention is to provide a modular viewing systems, essentially comprising a resr-mounted video camera, or cameras, and a forward-mounted electrni display screen, that is adaptable to ny type of vehicle and provides a clear rearwad view, irrespective of the type of vehicle, and thus provides an improvement in the ease and safety T7ith which a vehicle may be driven, including driving in reverse.
A second object is to provide a system that is flexible to further adaptation for the provision of additional facilities, such as the remote security monitoring of a vehicle, and the recording of road events during the vehicle's journeys, for evidential- purposes.
A still further object of the invention is to utilise, where appropriate, mirrors in conjunction 5tith electronic image capture, transmission and display means such that a mirrorimage of a rear-view scene captured in a first mirror mounted aft of the vehicle driver may be clearly displayed in a second mirror mounted to the front of the driver, with suitable magnification as may be desirable. The purpose of this object is to enable image scanning and image display device modules of compact size to be mounted in the most space-saving orientation, Dor example vertically rather than horizontally, the mirror re-directing the image through an optimum angle of inclination. In this Way mrny different types and sizes of video camera and display screen, whose longitudinal dimension may be lass well suited to horizontal mounting on a dashboard or rear parcel shelf, may be utilised to suit different requirenents such as lens and screen size as is most appropriate to a particular vehicle. Thus, for example, a cathode ray tube television monitor may be vertically mounted with itS screen in an essentially horizontal plane without causing an undue obstruction of the indscreen.
According tn the present invention, therefore, there is provided a modular rearward viewing system, with universally variable fields of view, comprising one or more video cameras, an electronic visual display screen, means for interconnecting and controlling the camera(s) and display screen, the cameras and display screen being adapted respectively to be each co-operable ir close conjunction with an adjustably piVoted, demountable mirror, said mirrors being angled above the camera lens and display screen respectively by a pivot or hinge means the camera(s), display screen and mirror unit(s) having adjustable angles of inclination relative to one another and being so arranged within he'r appropriate hou ings, as to transmit electronically, from the rear-most camera or mirror, a rear-View image to the disnlay screen, said screen being mounted in the least space consuming orientation to a suitable and adjustable anchorage point in front of the vehicle's driver position. The display screen is preferably a flat-panel display of a width, depth and height comparable to that of a conventional internally mounted rear-view mirror, but may also be a cathode-ray tube television of compact size.
The cameras and respective mirror units are preferably housed jn a protective enclosure in which they may be preset to an optimum inclination or in which they may be adjusted by means of adjustment screws after the housing has been mounted, fAe housing having a suitable observation window through which the camera unit may focussed. T"e housing may have a hinged lid which can be opened and supported at a suitable inclinption by means of springs or support arms. Scissor or trellis arms would be suitable. The said units may then be mounted at aly appropriate and advantageous position on the vehicle. This may be externally of the vehicle, such as a central position on fhe roof end or the rear bumper of a lorry, or internally in proximity to t e rear Window of a bus, coach or a towed caravan, for example. For externally mounted camera modules the housing is preferably a weather proof sealed unit. To permit a camera panning facility the housing may incorporate a motor driven turntable or similar means. Alterritivey, the camera module may be incorporated within the vehicle's rear light lens assembly suitably adapted to accept the camera.
In terms of component modules all the technical requirements for providing the desired essential features of the present invention are readily commercially available as modules and may be assembled or interconnected, by persons skilled in the art, in various combinations and configuarations to suit particular preferences, adaptations, additional features, modes of signal generation, modulation, transmission, reception and methods of control as may be appropriate to a particular type of vehicle.
For example, small video cameras are available in the form of what are known as board cameras, with good sensitivity to dark or low liht levels, while electronic display screen means are available as cathode-ray television monitors, liquid crystal display screens and many other types of flat electronic display screens. A small, flat cathode-ray television monitor with a four inch screen is knorn to be available and is use extensively in door entry systems.
Currently, the required flat-panel display screens available are not of the preferred size. Horzever, the smaller of such screens may still be utilised by combining them with a mirror airing a suitable scale of image magnification. This may be in conjunction with a lens, diffraction grating or similar means for epanding the image size. Alternatively, more than one such flat-panel display screen may be combined side-by-side and means for dividing tte camera image provided so that each display shows a portion of the camera image. In this way the the driver's display screen may be kept as small as possible and be mounted in the normal overhead position rather than on ke dashboard.
Alternatively, an image display receptacle as described in GB patent applScrtion No. 9612917.6 may be specifically adapted for use with the preset invention.
Preferably, camera switching means, including multiplex, memory, and micro?rocessor control and selecting means, are provided for sequentially stitching the display from one camera view to another, for combining the views of more than one camera on the display screen simultaneously and for retaining recorded images rev dental purposes.
For some vehicles the transmission means is preferably wireless, that is to say the video images are broadcast in television image equality from the camera to tXe display screen by a television transmitter module and received at the display screen -jia an spiel and radio frequency receiver module with signal converter as appropriate. The picture signal may also be transmitted by the irradirtion of modulated infra-red light beams. Such embodiments may thus cater for all types of vehicle, but may not alaays be economically justifiable in a vehicle which has a body rigidly fixed to the driver's compartment. Alternatively, therefore, the video signal may be transmitted through a wire, such as a coaxial video cable, connected between the camera means and video image display means, or may be transmitted as digital patterns of pulsed light signals along a fibre-optic cable connected between suitable transmitter and receiver modules. Preferably, provision is ma*v.e for a comnination of wireless and wired transmission and reception means to be employed, especiallyWith respect to Opto-electronic image transmissions, thereby enabling cable runs to be confined to areas where they do not cause inconvenience. Alterntive1.y, such modules may be incorporated essentially into two integrates circuit modules with suitable interfacing means to permit the attachment and connection of the transmission and reception module means most suitable to a particular vehicle.
In some embodiments te transmitted signal may be a composite video signal, or aalogue; n others it may be a dig.tised signal, the particular signal mode being compatibly matched to he respective camera, screen display means and mode of transmission and reception. Optionally, the image displayed may be monochrome or in colour, and infra-red emitting means may be provided to enhance the camera's operation in times of da kness.
The orientation of the camera means relative to the mirror means may be manually adjustable or electro-mechanically adjustable, according to whether the viewing system is to provide a purely rear-view viewing facility or tle optional addition of vehicle security monitoring facilities with a variable field of view. In tune latter embodiment the mirror means is preferably arranged to be rotative to scan through 350 degrees under motor driven power, thereby providing a viable field of view. This may be bi-directional and driven by a steppes motor. Tie basic orientation of the camera means is envisaged to be near vertical and focussed on the central image area of the mirror inclined over the lens, but bi-directionally adjustable bacw.^^rd and forwards through a sufficient degree of arc as to be able to occupy horizontal orientations as well, to provide a tilt facility, including a direct view unaided by te mirror means trough the window in the protective housing.
Thus the camera may face rearward in an essentially horizontal orientation, or any suitable angle of inclination, face near vertically in its normal orientation, or forward in a further horizontal orientation or at any angle of inclination in between said orientations. When the video image originates solely from the video camera the camera must be capable of having its horizontal scan reversed so as to produce a true mirror image on the display screen. A line-lock facility is also preferably provided. The advantage of focussing a video camera on a rearward facing angled mirror above the camera lens is that a miniature camera can thus produce a larger image of higher quality definition on the display means and be mounted in the least space consuming orientation. Cameras lacking a reversibly switchable mirror-image facilty may also be deployed without need of modification. The mirror may also be masked to produce a shaped image area conforming with the shape of the electronic display screen means.
A specific embodiment of the present invention in its most basic form Will now be described by way of example together with some optional alternatives.
The modular rearward viewing system comprises, within a protective housing, which may have a hinged lid, a video camera module with video signal transmitting means, whereby, when the lid is opened and supported in a vertical or near vertical plane by adjustable legs, or when the camera is focussed on the appropriately inclined, rearward facing, angled mirror above tie camera lens, the video signal transmitting means transmits the video image from the camera to an electronic disnlay screen means mounted on a suitable anchorage point in front of the vehicle driver's line of view, the display screen means being similarly adapted, depending on its bulk, to be co-operable with an image re-directing mirror, thereby providing a natural, high definition, full-size mirror-image of the space to the rear of the vehicle. More than one camera system may be deployed at suitable locations on one vehicle and switching means be provided for selectively displaying different camera views sequentially or in combination . The camera and the mirror modules are pivotally mounted and thus adjustable relative to one another and thereby able to provide variable fields of view through panning and tilting. Tze camera module mirror may optionally be imbedded in the hinged lid of the housing. EZhen the hinged lid is closed the inclined mirror is folded down on its own hinges to lay flat above the camera means.
The transmitting means may be hrrd-Wired to the driver's display screen or it may be wireless by provision of radio transmitter means.
Motor drive means may be provided for electro-mechanical rotative adjustment of the mirror radially about the normally near upward facing camera, thereby permitting the mirror to pan through a 360 degree field of view. The camera lens or lenses may be of fixed or variable focal length. A preferred variable focus lens may be motor driven for focus control.
Alternatively, a flexible, transparent membrane, variable focus lens, containing water or silicon oil, may be adjusted for focus and magnification by increasing or decreasing the pressure of fluid between the membrane layers by a motor driven pump.
Control circuitry powered by the vehicles electricity supply may be housed in the camera housing, the display screen module or may be provided in a separate housing.
In an extended embodiment of the basic present invention, security surveillance of the vehicle is provided by remote radio control means of the camera and mirror means, preferably by cellular radio telephony means and optionally in conjunctionWith an alarm and appropriate sensors. A driver may thus telephone his vehicle and obtain real time images of the security of his veh cle, or he may be automatically alerted through the alarm sensor activating an auotomatic dial-up facility. Optionally, a partially silvered mirror, mounted forward of the driver, may be incorporated with a miniature video camera behind, so as to provide means of covertly monitoring the identity of the driver. The driver's image may be transmitted through a celluar radio telephone link or similar means to a central control station for driver verification before remote control means governing the running of the engine, permit the engine to be started.
It will be appreciatod that many alternntnve embodiments may be fashioned from the basic form and that such modifications, including digital microprocessor data processing and presentation of many types of information useful to the driver, may be provided by adding modular acccessories to a basic modula system.