GB2415568A - Wireless video signal transmission system for vehicles - Google Patents

Wireless video signal transmission system for vehicles Download PDF

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Publication number
GB2415568A
GB2415568A GB0512737A GB0512737A GB2415568A GB 2415568 A GB2415568 A GB 2415568A GB 0512737 A GB0512737 A GB 0512737A GB 0512737 A GB0512737 A GB 0512737A GB 2415568 A GB2415568 A GB 2415568A
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United Kingdom
Prior art keywords
master
video
control means
video camera
signals
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Granted
Application number
GB0512737A
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GB0512737D0 (en
GB2415568B (en
Inventor
Patrick Eoghan Denny
Patrick John Lyons
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Hi Key Ltd
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Hi Key Ltd
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Publication of GB0512737D0 publication Critical patent/GB0512737D0/en
Publication of GB2415568A publication Critical patent/GB2415568A/en
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Publication of GB2415568B publication Critical patent/GB2415568B/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/18—Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast
    • H04N7/183—Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast for receiving images from a single remote source

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Closed-Circuit Television Systems (AREA)

Abstract

A video signal transmission system for transmitting video signals from a remotely mounted video camera (2) to a vehicle mounted video signal processing unit (3) for display on a vehicle mounted visual display screen (4). An on-board master control unit (5), which controls the operation of the video camera (2), receives video signals from the video camera (2), and relays the video signals to the video signal processing unit (3). Initially, a master microprocessor (15) of the master control unit (5) selects the least noisy channel, and sets the transmission channel of a slave transmitter (34) of the video camera (2) and the receive channel of a master receiver (17) of the master control unit(5) to the selected channel. A master transmitter (16) of the master control unit (5) under the control of the master microprocessor (15) transmits control signals to a slave microprocessor (31) of the video camera for reception by a slave receiver (33) for selecting the transmission channel of the slave transmitter (34). The master transmitter (16) under the control of the master microprocessor (15) outputs a predetermined signal at predetermined intervals for reception by the slave receiver (33). Absence of reception of the predetermined signal by the slave receiver (33) indicates that the video camera (2) is out of range of the master control unit (5), and the video camera (2) is put into a sleep mode. The system may be used to provide a rear view when reversing.

Description

24 1 5568 HA video signal transmission system, and a method for
transmitting a video signal from a remotely mounted video camera to a vehicle mounted video signal processing unit" s The present invention relates to a video signal transmission system for transmitting video signals front a remotely mounted video camera to a vehicle mounted video signal processing unit, for example, to an on-board video signal processing unit in a motor vehicle, for subsequent display on a vehicle mounted visual display screen.
The invention also relates to a method for transmitting a video signal from a remotely lo mounted video camera to a vehicle mounted video signal processing unit for subsequent display on a vehicle mounted visual display screen. The invention further relates to a video camera for use in the video signal transmission system.
The use of video cameras on motor vehicles is known. Such video cameras are particularly used for providing the rear view presented to a driver when reversing on a visual display screen. However, in general, such video cameras are rigidly mounted to the vehicle, or at best may be swivellably mounted to the vehicle, but in all cases are hardwired to the vehicle. Thus, such video cameras essentially do little more than increase the field of view presented to a driver over and above that which zO would be presented in a rear view mirror. While increasing the field of view for facilitating reversing of the vehicle is undoubtedly of assistance to a driver, there are many cases where a vehicle mounted video camera fails to present a driver attempting to reverse a vehicle in a relatively confined space with an adequate view of the confined space to facilitate reversing, and in general' in such cases it is as necessary for the driver to rely on a third party to provide directions while carrying out the reversing rnanoenvre.
There is therefore a need for a video signal transmission system which overcomes this problem.
The present invention is directed towards providing such a video signal transmission system and a method for transmitting a video signal, as well as a video camera.
According to the inversion there is provided a video signal transmission system for transmitting a video signal from a remotely mounted video camera to a vehicle mounted video signal processing unit for display on a vehicle mounted visual display s screen, the transmission system comprising: a video camera suitable for mounting remotely of the vehicle, a vehicle mountable master control means for controlling transmission of video signals from the video camera to the vehicle mounted signal processing unit, a vehicle mountable master transmitter operable under the control of the to master control means her transmitting control signals from the master control means to the video camera for controlling operation of the video camera, a vehicle mountable master receiver for receiving video signals from the video camera, the master receiver having at least two selectable channels for receiving video signals from the video camera, the channels being selectable by the master control means, the master receiver comprising an amplifier, and a gain control means for controlling the gain of the amplifier For amplifying signals on the respective channels to a predetermined power level, a slave control means associated with the video camera for operating the video camera in response to the control signals received from the master control means, a slave receiver associated with the video camera for receiving the control signals from the master control means transmitted by the master transmitter for relaying to the slave control means, and a slave transmitter associated with the video camera for transmitting video signals therefrom to the master control means, the slave transmitter having at least two selectable channels on which video signals from the video camera are transmittable, the frequencies of the respective channels of the slave transmitter corresponding to the frequencies of the respective channels of the master receiver, the master control means comprising: a first selecting means for sequentially selecting at least some of the channels of the master receiver, a reading means for reading respective gain signals from the gain control newels of the master receiver indicative of the amplification factors by which signals on the respective selected channels are amplified to bring the signals thereon to the predetermined power level for determining the noise level on the selected channels, and a second selecting means responsive to the gain signals read by the reading newels for selecting the channel of the slave transmitter and the master receiver on which the video signals are to be communicated from Me video camera to the master control means, the master control means being responsive to the second selecting means selecting the channel, for setting the master receiver to the selected channel, and for outputting a channel select signal through the master transmitter to the slave control means, the channel select signal indicating the identity of the channel of the slave transmitter which is to be selected by the slave control means for transmitting the video signals from the video camera to the master control means, and the slave control means is responsive to the channel select signal for setting the slave transmitter to the selected channel.
Preferably, the second selecting means is responsive to the gain signals for selecting the channel of the master transmitter, the gain signal for which is indicative of one of the higher amplification factors, In one embodiment of the invention the first selecting means is operable under the control of the master control means for sequentially selecting the at least some of the channels of the master receiver for determining the noise levels thereon when the slave transmitter is not transmitting.
In another embodiment of the invention the reading means is operable under the control of the master control means for reading signals on the channels of the master receiver selected by the first selecting means for determining if any of the selected channels contain a video signal.
Advantageously, the second selecting means is responsive to the reading means and the gain signals for selecting the channel of the master receiver which does not q contain a video signal and the signal on which is amplified by the amplification factor which is highest of the amplification factors of the selected channels which do not contain a video signal.
Preferably, the first selecting means is operable under the control of the master control means in response to an externally generated video activation signal inputted to the master control means for activating the video camera.
In one embodiment of the invention the slave control means is responsive to the channel select signal for activating the video camera to commence operation.
Preferably, the first selecting means is operable under the control of the master control means for sequentially selecting all of the channels of the master receiver.
Is Advantageously, the signals on the selected channels of the master receiver when the channels are being sequentially selected by the first selecting means is ideally noise.
In one embodiment of the invention a storing means is provided for storing the gain z0 signals for the selected channels cross-referenced with identities of the corresponding channels.
In another embodiment of the invention the storing means stores the identities of the selected channels which contain a video signal, In a further embodiment of the invention the master control means is responsive to an externally generated alternative channel request signal for selecting a channel the gain signal of which is indicative of an amplification factor, the value of which is substantially similar to that of the selected channel of the master receiver and the so slave transmitter. Preferably, the master control means is responsive to the externally generated alternative channel request signal only when the master receiver is receiving video signals from the video camera. s
{n another embodiment of the Invention the master control means comprises a means for generating a predetermined signal at first predetermined intervals for transmission through the master trarrsmitter to the slave control means after the channel select signal has been transmitted to the slave control means, and the slave control means is responsive to the absence of reception of the predetermined signal for deactivating the video camera.
Preferably, the slave control means is responsive to the absence of each of the predetermined signals during a period corresponding to a predetermined number of the first predetermined intervals for deactivating the video camera.
Advantageously, the slave control means is responsive to the absence of each of the predetermined signals during a period corresponding to the predetermined number of the first predetermined intervals plus a predetermined safety time period for deactivating the video camera.
In one embodiment of the invention the safes time period is in the range of one second to ten seconds. Preferably, the safety time period is in the range of three zo seconds to seven seconds. Advantageously, the safety time period is approximately five seconds.
In one embodiment of the invention the predetermined number of the first predetermined intervals does not exceed five first predetermined intervals.
:S Preferably, the predetermined number of the first predetermined intervals does not exceed three first predetermined intervals. Advantageously, the predetermined number of first predetermined intervals is two first predetermined intervals.
In one embodiment of the invention each first predetermined interval is in the range of forty seconds to eighty seconds. Preferably, each first predetermined interval is in the range of fifty-five seconds to sixtyfive seconds. Advantageously, each predetermined interval is approximately sixty seconds.
Preferably, the master control means transmits the predetermined signal at the first predetermined interval in response to reception of the video signal from the video camera.
In one embodiment of the invention the master control means is responsive to the absence of reception of the video signal from the video camera for transmitting the predetermined signal at second predetermined intervals, and the slave control means is responsive to the predetermined signals for reactivating the video camera 0 to transmit the video signal.
Preferably, each second predetermined interval is in the range of five seconds to twenty-five seconds. Advantageously, each second predetermined interval is in the range of ten seconds to fifteen seconds. Ideally, each second predetermined Is interval is approximately twelve seconds.
In another embodiment of the invention the predetermined signal includes the channel select signal.
In one embodiment of Me invention the slave control means operates the slave receiver for receiving the predetermined signals.
In another embodiment of the invention the master control means operates the master transmitter for transmitting the predetermined signal on a predetermined 2s channel.
Preferably, the slave control means operates the slave receiver for receiving the predetermined signal on a channel corresponding to We predetermined channel on which the predetermined signal is being transnniffed by the master transmitter.
In one embodiment of the invention the master transmitter is a narrow band transmitter.
In another embodiment of the invention the slave receiver is a narrow band receiver, and the slave control means sweeps the slave receiver through frequency channels corresponding to the frequency channels of the narrow band receiver for determining S the channel on which the predetermined signal is being transmitted by the master transmitter.
Preferably, the video camera comprises a light source for projecting light to an area being videced by the video camera. Preferably; the light source is provided by at least one light emitting diode. Advantageously, the light source is provided by a plurality of light Unfitting diodes. Ideally, each light transmitting diode outputs light with a relatively high infrared content.
In one embodiment of the invention the slave control means is responsive to the channel select signal for activating the light source when the video camera is being activated.
In another embodiment of the invention the master control means is responsive to video signals being received by the master receiver for relaying the video signals to the vehicle mounted video signal processing unit.
In a further embodiment of the invention the master control means is responsive to video signals being received by the master receiver for relaying the video signals to the signal processing unit so Mat an image resulting from the video signal when displayed on the visual display screen is presented in an orientation corresponding to the image which would appear in a rear view mirror of a vehicle.
Additionally the invention provides a method for transmitting a video signal from a remotely mounted video camera to a vehicle mounted video signal processing unit for display on a vehicle mounted visual display screen, the method comprising the steps of; providing a video camera suitable for mounting remotely of the vehicle, providing a vehicle mountable master control means for controlling transmission of video signals from the video camera to the vehicle mounted signal processing unit, providing a vehicle mountable master transmitter operable under the control of the master control means for transmitting control signals from the nester control means to the video camera for controlling operation of the video camera, providing a vehicle mountable master receiver for receiving video signals from the video camera, the master receiver having at least two selectable channels for receiving video signals from the video camera, the channels being selectable by to the master control means, the master receiver being provided with an amplifier and a gain control means for controlling the gain of the amplifier for annplifying signals on the respective channels to a predetermined power level, providing a slave control means associated with the video camera for operating the video camera in response to the control signals received from the IS master control means, providing a slave receiver associated with the video camera for receiving the control signals from the master control means transnnitted by the master transmitter for relaying to the slave control means, providing a slave transmitter associated with the video camera for transrniffing video signals therefrom to the master control means, the slave transmitter having at least two selectable channels on which video signals from the video camera are transmittable, the frequencies of the respective channels of the slave transmitter corresponding to the frequencies of the respective channels of the master receiver, providing the master control means with a first selecting means for sequentially selecting at least some of the channels of the master receiver, a reading means for reading respective gain signals from the gain control means of the master receiver indicative of the amplification factors by which signals on the respective selected channels are amplified to bring the signals thereon to the predetermined so power level for detennining the noise level on the selected channels, and a second selecting means responsive to the gain signals read by the reading means for selecting the channel of the slave transmitter and the master receiver on which the video signals are to be communicated from the video camera to the master control means, the master control means being responsive to the second selecting means selecting the channel, for setting the master receiver to the selected channel, and for outputting a channel select signal through the master transmitter to the slave control means, the channel select signal indicating the identity of the channel of the slave transmitter which is to be selected by the slave control means for transmitting the video signals from the video camera to the master control means, and the slave control means is responsive to the channel select signal for selecting the channel of the slave transmitter, the method further comprising the steps of: operating the first selecting means for sequentially selecting at least some of the channels of the master receiver, operating the reading means for reading respective gain signals from the gain control means of the master receiver indicative of the amplification factors by which signals on the respective selected channels are amplified to bring the signals thereon to the predetermined power level, operating the second selecting means to be responsive to the reading means for selecting the channel of the slave tranenitter and the master receiver on which the video signals are to be communicated from the video camera to the master control means, operating the master control means in response to the second selecting means selecting the channel for setting the master receiver to the selected channel, and for outputs ng a channel select signal from the master transmitter to the slave control means for indicating the identity of the channel of the slave transmitter which iS to be selected for transmitting the video signal from the video camera to the master control means, and operating the slave control means in response to the channel select signal for setting the channel of the slave transmitter, s0 Preferably, the second selecting means is operated to be responsive to the gain signals for selecting the channel of the master transmitter, the gain signal for which is indicative of one of the higher amplification factors.
Advantageously, the first selecting means is operated under the control of the master control means for sequentially selecting the at least some of the channels of the master receiver for determining the noise levels thereon when the slave s transmitter is not transmitting.
Ideally, the reading means is operated under the control of the master control means for reading the signals on the selected channels of the master receiver selected by the first selecting means for determining if any of the selected channels contain a lo video signal.
Preferably, the second selecting means is operated to be responsive to the reading neans and the gain signals for selecting the channel of the master receiver which does not contain a video signal and the signal on which is amplified by the amplification factor which is highest of the amplification factors of the selected channels which do not contain a video signal.
The invention also provides a video camera for use in the video signal transmission system according to the invention' the video camera comprising a housing having a hollow interior region. a main printed circuit board located in the hollow interior region, a video camera unit mounted on the main printed circuit board within the hollow interior region, a secondary printed circuit board located within the hollow interior region, the secondary printed circuit board being electrically coupled to the main printed circuit board, a locating means for locating the niacin and secondary :5 printed circuit boards relative to each other for facilitating electrical coupling thereof, and an alignment means for facilitating correct alignment and location of the main and secondary printed circuit boards within the hollow interior region of the housing In one embodiment of the invention a main guide track is provided for receiving the so main printed circuit board in the hollow interior region of the housing.
In another embodiment of the invention a secondary guide track is provided for receiving the secondary printed circuit board in the hollow interior region of the housing.
Preferably, an opening is provided in the secondary printed circuit board for accommodating the video camera unit front the main printed circuit board therethrough.
Advantageously, the locating means comprises a key formed on one of the video camera unit and the secondary printed circuit board, and a key-way formed on the lo other of the video camera unit and the secondary printed circuit board for co- operating with the key for locating the main and secondary printed circuit boards relative to each other.
Advantageously, the alignment means comprises an alignment projection extending from one of the housing and the secondary printed circuit board, and an alignment recess formed in the other of the housing and the secondary printed circuit board for co-operating with the alignment projection for correctly aligning and locating the main and secondary printed circuit boards in the hollow interior region of the housing.
In one embodiment of the invention a main lens is provided in the housing aligned with the video camera unit when the main and secondary printed circuit boards are correctly aligned and located in the hollow inferior region of the housing.
Advantageously, a light source is provided on the secondary printed circuit board for lighting an area being videoed by the video camera. Preferably, a plurality of light sources are located on the secondary printed circuit board.
In one embodiment of the invention a secondary lens is provided in the housing corresponding to each light source for accommodating light from the corresponding light source therethrough.
The invention will be more clearly understood from the following description of a preferred embodiment thereof, which is given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a block representation of a video signal transmission system according to the invention for transmitting a video signal from a remotely mountable video camera to a vehicle mountable video signal processing unit, Fig. 2 is a block representation of a flow chart of a subroutine of a computer prograrnme for controlling the operation of the video signal transmission lo system, Fig. 3 is a block representation of a flow chart of a further subroutine of a computer programme for controlling the operation of the video signal transmission system, Fig. 4 is a front elevational view of the remotely mountable video camera of the system of Fig 1, Fig. 5 is a top plan view of the video camera of Fig. 4, Fig. 6 is a perspective view of a portion of the video camera of Fig. 4, Fig. 7 is a perspective view of the portion of Fig. 6 of the video camera of Fig. 4 with part of the video camera removed, Fig. 8 is a partly cross- sectional front elevational view of a detail of the portion of the video camera which has been removed from the portion illustrated in the perspective view of Fig. 7, Fig. 9 is a top plan view of a portion of the detail of Fig. 9 of the video camera of Fig. 4, and Fig 10 is a top plan viev'of another portion of the detail of Fig. 8 of the video camera of Fig. 4.
Referring to the drawings and initially to Fig. 1, there is illustrated a video signal transmission system according to the invention, indicated generally by the reference numeral 1, for use with a motor vehicle (not shown) for transmitting video signals from a remotely mountable video camera, also according to the invention, which is indicated generally by the reference numeral 2, to a vehicle mounted on-board video signal processing unit 3 for display on a visual display screen 4 also mounted in the motor vehicle. Such on-board video signal processing units are commonly provided in motor vehicles for processing video signals read from a compact disc or a DVD with route nip data for displaying the map of a route to be followed or being followed on an on-board visual display screen. Such on-board video signal processing units may also be provided for processing video signals transmitted by television stations for displaying a television programme on the visual display screen 4. Accordingly, such on-board video signal processing units and visual display screens located in motor vehicles will be well known to those skilled in the art, and it is not intended to describe the video signal processing unit 3 or the visual display screen 4 in further detail. A vehicle mountable on-board master control unit, also according to the invention, which is illustrated in block representation in Fig. 1, arid which is indicated generally by the reference numeral 5, is located onboard the motor vehicle for controlling the operation of the video camera 2, for receiving video signals from the video canters 2, and for relaying the video signals to the video signal processing unit 3.
In this embodiment of the invention the video camera 2 comprises a housing 6 as will be described below with reference to Figs. 4 to 10, and is suitable for mounting on the vehicle or remotely of the vehicle. When mounted on the vehicle, typically, the video camera 2 is mounted to the rear of the vehicle for presenting a view to the s0 rear of the vehicle on the visual display screen 4 to a driver for assisting in reversing of the vehicle When mounted remotely of the vehicle, the video camera 2 would typically be located for capturing images of an area within which the vehicle is to be or is being manoeuvred.
A camera receiving unit (not shown) is provided for mounting on the rear of the vehicle or any other desired location in or on the vehicle for receiving the video s camera 2 when the video camera 2 is to be mounted on the rear of the vehicle, and also for orienting the video camera so that the video camera 2 videos the area into which the vehicle is being reversed or otherwise manoeuvred. When located in the camera receiving unit (not shown), the video camera 2 communicates with the master control unit 5 through an infrared communication link. A first infrared transmiffer/receiver unit 9 of the infrared comnunicaffon link is provided associated with the master control unit 5, and is located in the camera receiving unit (not shown). A second infrared transmitter/receiver unit 10 of the infrared communication link is located in the video camera 2 for communicating with the first infrared transmitter/receiver unit 9, A port 11 in the housing 6 of the video camera 2, see Fig, 4, is provided for facilitating infrared transmissions between the second infrared transmitter/receiver 10 in the video camera 2 and the first infrared transmitter/receiver 9 in the camera receiving unit (not shown).
The video camera 2 is powered by a rechargeable battery (not shown) which is charged from the electrical system of the motor vehicle when the video camera 2 is located in the camera receiving unit (not shown), A pair of electrical contacts 12 located on the housing 6 of the video camera 2, see Fig. 4, engage a corresponding pair of electrical contacts (not shown) located in the camera receiving unit knot shown) for powering the video camera 2 when the video Canberra 2 is located in Me camera receiving unit, and for charging the battery of the video camera 2.
Retuming now to the on-board master control unit 5, and referring to Fig. 1, the master control unit 5 comprises a master control means, namely, a master microprocessor 15, which controls the operation of the video transmission system 1, and also controls the operation of the video camera 2 through the video signal transmission system 1. A master radio transmitter 16, which in this embodiment of the invention is a narrow band transmitter is operated under the control of the master microprocessor 15 for transmitting control signals to the video camera 2, as will be described below, for controlling operation of the video camera 2 when the video Canberra 2 is removed from the camera receiving unit (not shown), and is located remotely of the vehicle. s
A master video receiver 17, which is also operated under the control of the master microprocessor 15, receives video signals from the video camera 2 for relaying to the video signal processing unit 3 when the video camera is located remotely of the vehicle. The master receiver 17 is amultichannel ISM band receiver comprising to four selectable channels for receiving video signals from the video camera 2, as will also be described below. An antenna and a front end filter 18 of the master receiver 17 receives signals, which are relayed to a tuning circuit 20, which selects the appropriate one of the four receiving channels of the master receiver 17, as will be described below. A demodulation and correction circuit 21 demodulates the lS received video signals, and under the control of the master microprocessor 15, the demodulated video signals are relayed to the video signal processing unit 3 for display on the visual display screen 4.
The tuning circuit 20 comprises a signal mixer 22 for mixing received signals from the antenna and front end filter 18 of the master receiver 17 with a frequency signal outputted by a programmable local oscillator 25, which is operated under the control of the master microprocessor 15 for setting the channel frequency of the master receiver 17 to a selected channel frequency. An intermediate frequency variable gain amplifier 26 amplifies the intermediate frequency signal outputted by the mixer 2S 22. A gain control circuit 28 controls the gain of the arnplif Or 26 so that the intermediate frequency signal is amplified to a constant predetermined power level for determining the noise level in the respective channels. As the master microprocessor 15 as will be described below sequentially selects the channels of the master receiver 20, the signals on the respective selected channels are amplified to the predetermined power level, and the master microprocessor 15 reads the gain control signal from the gain control circuit 28, which is applied to the intermediate frequency amplifier 26, for determining the amplification factors by which the signal on the selected channels are amplified by the intermediate frequency amplifier 26 for determining the noise level in the respective selected channels.
Turning now to the video camera 2 and referring in particular to Fig. 1, the video s camera 2 comprises a CMOS video camera unit 30 which is operated under the control of a slave control means, namely, a slave microprocessor 31. A slave radio receiver 33 operated under the control of the slave microprocessor 31 communicates the slave microprocessor 31 with the master microprocessor 15 for receiving control signals from the master microprocessor 15 for controlling the ID operation of the video camera 2 and the video camera unit 30 when the video camera is located remotely of the vehicle. The slave radio receiver 33 is a narrow band receiver having a corresponding receiving frequency range as the master transmitter 16. and is of the type capable of sweeping through the frequency range for detecting a valid control signal and other signals from the master transmitter 16.
Such sweeping techniques in radio receivers for detecting a valid signal will be well known to those skilled in the art. A slave video signal transmitter 34, which is also operated under the control of the slave microprocessor 31 transmits video signals from the video camera unit 30 for reception by the master receiver 17 when the video camera is located remotely of the vehicle. The slave transmitter 34 is a multi channel transmitter, and is operable under the control of the slave microprocessor 31 for transmitting the video signals from the video camera unit 30 on four selectable channels, the respective frequencies of which correspond to the frequencies of the four selectable channels of the master receiver 17 A light source, in this embodiment of the invention six light emitting diodes 35, which have a high infrared light content are provided in the video camera 2 for illuminating an area being videoed by the video camera unit 30. The arrangement and location of the light emitting diodes 35 is described in more detail below with reference to Figs. 4 to 10. The light emitting diodes 35 are operated under the control of the So slave microprocessor 31 in response to control signals received from the master microprocessor 15.
The operation of the video signal transmission system will now be described. When the video camera is mounted remotely of the vehicle (not shown) the video camera 2 awaits a channel select signal from the master control unit 5, which indicates to the slave microprocessor 31, firstly that the video camera 2 is to be activated to transmit s video signals to the nester control unit 5, and secondly the identity of the channel of the slave transmitter 34 on which the video signals from the video camera unit 30 are to be transmitted. The master control unit 5 is initially activated in response to a video activation signal for outputting the channel select signal to the video camera 2.
The video activation signal which is applied to Me master control unit 5 is inputted by a user through a suitable input means located in the vehicle. The input means may be a push button switch (not shown) which would be operated by the driver or an individual in the vehicle, or any other suitable arrangement for inputting the video activation signal.
On receipt of the video activation signal, and before outputting the channel select signal to the video camera 2, the master control unit 5 initially determines which of the four channels of the master receiver 17 and the slave transmitter 34 is the optimum channel for transmission of the video signals, in other words, which is the least noisy of the four channels.
The least noisy channel is determined as follows. The microprocessor 15 on receipt of the video activation signal operates the tuning circuit 20 of the master receiver 17 for sequentially selecting the four receiving channels. As the four channels are sequentially selected, the signals on the selected channels are gained up to a us predetermined power level by the amplifier 26 under the control of the gain control circuit 28 Since the video camera 2 at this stage is not transmitting, the only signals which should be on the four channels as the channels are being sequentially selected is noise. The master microprocessor 15 reads the gain control signals from the gain control circuit 28 for determining the amplification factor by which the so signals, in other words, the noise on the respective channels, is amplified to bring the signals on the respective channels to the predetermined power level. The master microprocessor 15 also reads the signals received on each of the channels to determine if any of the signals are video signals, which would indicate that a video camera other than the video camera 2 or other video transmitter is transmitting video signals, which would interfere with the video signals to be transmitted by the video camera 2. On the amplification factor for each selected channel having been s determined, and on the presence or otherwise of a video signal on the selected channel being detected, the amplification factor is stored in memory of the master microprocessor 15 and cross-referenced with the identity of the selected channel.
Additionally, an indication as to whether a video signal is present on the selected channel is also stored against the corresponding channel identity.
The master microprocessor 15 then selects the channel on which the amplification factor is highest, which does not contain a video signal. The channel with the highest amplification factor is the channel which will have the lowest noise level The master microprocessor 15 sets the master receiver 17 to receive on the selected channel, and then transmits the channel select signal through the master transmitter 16 for reception by the slave receiver 33 of the video camera 2. The slave microprocessor 31 on receiving the channel select signal operates the slave transmitter 34 to transmit on the channel identified by the channel select signal, and simultaneously activates the video camera unit 30 and the light emitting diodes 35.
Video signals from the video camera unit 30 are transmitted through the slave transmitter 34 under the control of the slave IT icroprocessor 31, and are received by the nester receiver 17. The received video signals are passed through the tuning circuit 20 and the demodulation and correction circuit 21, from which the video signals are relayed to the video signal processing unit 3 under the control of the master microprocessor 15, for display on the visual display screen 4.
In this embodiment of the invention the video signals are processed in the demodulation and correction circuit 21 for facilitating display of the video Enrage on the visual display screen 4 in positive or reverse form, in response to a suitable mode select signal. In the positive form the video image is as the object is videoed, while in reverse form the video image is as it would appear in a rear view mirror.
The mode select signal is entered by a driver through a suitable input interface (not shown).
In the event that during transmission of the video signal from the video camera 2, should noise appear in the image displayed on the visual display screen 4' by entering an alternative channel request signal through a suitable input interface (not shown), for example, a push button located on the dashboard of the vehicle, the transmission channel on which the video signal is being transmitted may be altered to a better channel. On receipt of an alternative channel request signal the master 0 microprocessor 15 reads the amplification factors stored against the other channels, and if an amplification factor substantially similar to that of the currently selected channel is found corresponding to another one of the channels of the master video receiver 17, and that channel does not have an indication of the presence of a video signal stored against it, the master microprocessor 15 selects that video channel and sets the master video receiver 17 to the newly selected channel. Simultaneously the master microprocessor 15 transmits a channel select signal identifying the new channel through the master transmitter 16 to the slave microprocessor 31, and on reception of the channel select signal, the slave microprocessor 31 operates the slave video transmitter 34 to transmit on the new channel. If none of the amplification factors of the remaining three channels of the master video receiver 17 are substantially similar to the amplification factor of the currently selected channel, or if such a channel contained a video signal, the master microprocessor 15 takes no action and the master video receiver 17 and the slave video transmitter 34 continue to transmit with the channel unaltered.
Additionally, in order to minimise the power consumption of the video camera 2, the master microprocessor 15 at first predetermined intervals, typically of sixty seconds duration, while the video camera 2 is transmitting video signals from the video camera unit 30, generates and operates the master transmitter 16 to output a predetermined signal, which includes the address of the video camera, for reception by the slave receiver 33 of the video camera 2. The slave microprocessor 31 monitors the slave receiver 33 for the predetermined signal at the first predetermined
JO
intervals. In the absence of two predetermined signals being received during two consecutive first predetermined intervals plus a safety time period of five seconds, which would indicate that the video camera 2 is outside the receiving range of the master receiver 17, the slave microprocessor 31 deactivates the video camera unit 30, the slave transmitter 34 and the light emitting diodes 35 and goes into a sleep/listening mode, and awaits the next predetermined signal or the next channel select signal when the vehicle and the video camera 2 come back into range of each other.
The transmission range of the master transmitter 16 is substantially similar to the transmission range of the slave video transmitter 34, and accordingly, when the slave receiver 33 fails to receive the predetermined signals, the video canters 2 is out of range of the master control unit 5, and in turn the master video receiver 17 of the master control unit 5 is thus out of range of the slave video transmitter 34 of the video camera 2.
The predetermined signal as well as including the address of the video camera 2 also includes the channel select signal, and accordingly, when the vehicle and the video camera 2 come back into range of each other, and the video camera receives the next predetermined signal, the slave microprocessor 31 reactivates tine video camera unit 30, the slave transmitter 34 and the light emitting diodes 35, and transmission of the video signal is recommenced.
Additionally, in orderto minimise the length of the periods during which the video as camera 2 is not transmitting when the vehicle and the video camera 2 go out of range of each other, the master microprocessor 15 is programmed so that when the master microprocessor 15 detects the absence of the video signal, the master microprocessor 15 transmits the predetermined signal through the master transmitter 16 at second predetermined intervals, which are shorterthan the first predetermined interval. In this case the second predetermined intervals are of twelve seconds duration. Accordingly, on receipt of one of the predetermined signals when the vehicle and the video camera 2 again come into range of each other, the video camera 2 is reactivated and transmission of the video signal is recommenced. The master microprocessor 15 on detecting the reception of the video signal reverts to transmitting the predetermined signal at the first predetermined intervals. In this way power consumption by the video camera 2 is minimised, since video transmission by s the video camera 2 only takes place while the vehicle and the video camera 2 are in range of each other.
When the video camera 2 is located in the camera receiving unit which is mounted on the vehicle, communication between the master microprocessor 15 and the slave microprocessor 31 is carried out through the first and second infrared transmitter/receivers 9 and 10, respectively.
Referring now to Fig. 2, there is illustrated a flow chart of a subroutine of a computer programme which controls the master microprocessor 15 for determining the least noisy charnel of the master video receiver 17. Block 40 commences the subroutine and sets a channel number m for identifying the channels equal to one. The number of channels available in the master video receiver 17, namely, four is represented by the number n. The subroutine moves from block 40 to block 41, which sets the master video receiver 17 to channel m and moves to block 42. Block 42 reads the zO gain control signal voltage Vm for channel rn, and stores the gain control signal voltage Vm for channel m cross-referenced with the channel number m in the memory of the master microprocessor 15. Block 42 also checks for the presence of a video signal in the channel m, and if a video signal is found, an indication of the presence of the video signal in channel m is stored against channel rn The subroutine then moves to block 43, which increments the channel number m by one and moves to block 44. Block 44 checks if the channel number m is less than the total number of channels n plus one, to ascertain if all n channels have been checked. If block 44 determines that all the channels have not been checked, the subroutine returns to block 41, which has already been described. If block 44 determines that all the channels have been checked, the subroutine moves to block 45.
Since the amplification factor is directly proportional to the gain control signal voltage Vm for each channel, block 45 selects the channel for which the gain control voltage signal Vm is highest, and also checks if an indication of the presence of a video signal is stored against the channel for which the gain control voltage signal is highest, and if not, the channel for which the gain control voltage signal is highest is confinned as the selected channel, and is identified as channel q On the other hand, if an indication of the presence of a video signal in the channel for which the gain control voltage signal is highest is revealed, the master microprocessor 15 under the control of block 45 selects the channel for which gain the control voltage signal Vm is the next highest, provided an indication of the presence of a video signal in that channel has not been detected, and so on.
The sub-routine then moves to block 46. Block 46 checks the gain control voltage signal Vm for each of the other channels, in other words For all the channels with the Is exception of the selected channel q which has been selected by block 45, and block 46 checks if there is another channel the gain control voltage signal Vm for which is equal to the gain control voltage signal Vq of the selected channel. If there is another channel for which the gain control voltage signal is equal to the gain control voltage signal Vq of the selected channel, block 46 identifies the channel for which go the gain control voltage signal is equal to the gain control voltage signal Vq of the selected channel q as channel p. Block 46 also checks if an indication of the presence of a video signal is stored against the channel p. If there is no indication of the presence of a video signal stored against the channel p, and if block 46 has determined that the gain control voltage signal Vp of channel p is equal to the gain as control voltage signal Vq of the selected channel q, the sub-routine moves to block 47 which stores the number p of channel p. The sub-routine then moves to block 48, which is described below. if on the other hand block 46 had determined that the gain control voltage signal of none of the other channels was equal to the gain control voltage signal Vq of the selected channel q, or if one was, that channel an contained an indication of the presence of a video signal stored against it, the sub- routine nerves directly from block 46 to block 48.
Block 48 sets the master video receiver to receive on channel q, and the sub-routine moves to block 49. Block 49 operates the master microprocessor 15 to transmit the channel select signal to the video camera through the master transmitter 6, with the channel select signal identifying channel q as being the channel to which the slave s video transmitter 34 is to be set for transmission of the video signal from the video camera unit 30. The sub-routine then moves to block 50, which returns control of the master microprocessor 15 to the main computer programme.
If during transmission of the video signal fronn the video camera, the video signal displayed on the visual display screen 4 contains noise, a user may enter the alternative channel request signal into the master control unit 5 which causes the master microprocessor 15 to operate under another sub-rouhne, which checks if a channel number has been stored by block 47 of the sub-routine of Fig. 2. If so the sub-routine (not shown) sets the selected channel q as being equal to the stored channel, namely, channel p, and the sub-routine then goes through to further steps, which are similar to blocks 48 and 49 of the sub-routine of Fig. 2. If block 47 of the sub-routine of Fig. 2 has not stored a channel number, the master microprocessor takes no action and the slave video transmitter 34 and the master video receiver 17 continue to transmit and receive on channel q selected and Set by block 45 of the 0 sub-routine of Fig. 2.
Referring now to Fig. 3, there is illustrated a flow chart of a subroutine which controls the slave microprocessor 31 for checking for the predetermined signal which is transmitted at the first predetermined intervals by the master transmitter 16 under the control of the master microprocessor 15 while the video signals are being received by the master video receiver 17. Block 66 starts the subroutine in response to a channel select signal received by the slave receiver 33 from the master transmitter 16, and the subroutine moves to block 66, which sets a timer to time zero, and the timer commences to time a time period equal to two first a0 predetermined intervals plus the predetermined safety time period of five seconds.
The subroutine then moves to block 67, which polls the slave receiver 33 for the predetermined signal, and moves to block 68. Block 68 checks if one of the predetermined signals has been received by the slave receiver 33, and if so, the subroutine returns to block 65. If block 68 determines that one of the predetermined signals has not been received by the slave receiver 33, the subroutine moves to block 69, which checks if the elapsed time being timed by the timer is greater than s the time period of two first predetermined intervals plus the predetermined safety time period. If not, the subroutine returns to block 67, which has already been described.
On the other hand, should block 69 determine that the elapsed time timed by the timer is greater than the time period of two first predetermined intervals plus the predetermined safety time period, the subroutine moves to block 70, which deactivates the video camera unit 30, the light emitting diodes 35 and the slave video transmitter 34, and returns the subroutine to block 67. Block 67 continues to pole the slave receiver 33 for the predetermined signal, or for a new channel select signal, and moves to block 68 which checks block 67 has received one of the predetermined signals, or a new channel select signal, and if so the subroutine is resumed to block 65. The sub-routine remains in the loop between blocks 65 and 68 until either the next predetermined signal or the next channel select signal is detected.
Referring now to Figs. 4 to 10, the housing 6 of the video camera 2 forms a hollow interior region 74, and a rear panel 73 of the housing 6 closes the hollow interior region 74. The video camera unit 30 is mounted on a main printed circuit board 75 which carries control circuitry for the video camera unit 30, which is located on the main printed circuit board 75 by surface mounted technology (SMT). The main printed circuit board 75 is located in the hollow interior region 74 of the housing 6 in a pair of main guide tracks 76, which align the video camera unit 30 with a main lens 77 in the housing 6. A secondary printed circuit board 78 carries We six light emitting diodes 35 of relatively high infrared content, and is located in the hollow so interior region 74 of the housing 6 in pair of secondary guide tracks 79. An opening 80 in the secondary printed circuit board 78 accommodates the video camera unit 30 therethrough. Connectors 81 and 82 are provided on the main and secondary printed circuit boards 75 and 78, respectively, for electrically coupling the printed circuit boards 75 and 78 together, and to control circuitry which comprises the slave microprocessor 31, the slave transmitter 34, the slave receiver 33 and the second infrared transmitter/receiver 10, and other relevant circuits which is also s located in the housing 6, but not illustrated in Figs. 4 to 10. Secondary lenses 89 in the housing 6 accommodate light from the light emitting diodes 35 for lighting the area being videoed by the video camera 2.
In order that the connectors 81 and 82 are accessible for facilitating electrical coupling by a suitable cable, it is important that the main and secondary printed circuit boards 75 and 78 are located in the housing with their respective side edges 83 and 84 arranged so that the connectors 81 and 82 are located one above the other as illustrated in Fig. 6. A locating means for so locating the secondary printed circuit board 78 relative to the main printed circuit board 75 is provided by a key 85 located on the video camera unit 30 for engaging a corresponding key-way 86 formed in the opening 80 of the secondary printed circuit board 78. An alignment means for correctly aligning the main and secondary printed circuit boards 75 and 78 in the hollow interior region 74 comprises an alignment recess 87 formed in the secondary printed circuit board 78, which co-operates with an alignment projection 88 extending from the housing 6 into the hollow interior region 74 for correctly locating the main and secondary printed circuit boards 75 and 78 in the hollow interior region 74 of the housing 6, and for preventing misassembly of the main and secondary printed circuit boards 75 and 78 in the housing 6.
as The main and secondary printed circuit boards 75 and 78 are assembled and located in the housing 6 as follows. Initially, the stuffed secondary printed circuit board 78 is mounted to the stuffed main printed circuit board 75 by engaging the video camera unit 30 on the main printed circuit board 75 in the opening 80 of the secondary printed circuit board 78, with the key 85 of the video camera unit 30 engaging the key-way 86. The assembled main and secondary printed circuit boards 75 and 78 are then engaged in the housing 6 by sliding the main and secondary printed circuit boards 75 and 78 into the main and secondary guide tracks 76 and 79, respectively, so that the alignment recess 87 engages the alignment projection 88. In this way, the connectors 81 and 82 together with the side edges 83 and 84 are located on corresponding sides of the video camera unit 30, with the connectors 81 and 82 one above the other, and thus can readily be connected to each other by a suitable connecting cable, and to the remaining control circuitry in the housing 6 likewise by suitable connecting cables. The alignment projection 88 prevents the nain and secondary printed circuit boards 75 and 78 being incorrectly located in the housing 8.
While the master receiver and the slave transmitter have been described as comprising four selectable channels, it will be readily apparent to those skilled in the art that the master receiver and the slave transmitter may be provided with any desired number of selectable channels. It will also be appreciated that while the master control unit has been described as outputting a predetermined signal at is predetermined intervals for reception by the video camera, while this is desirable, it is not essential, and furthermore, where the master control unit does output such predetermined signals at predetermined intervals, the signals may be outputted at predetermined intervals of any desired time period, and furthermore, the video camera may be responsive to the absence of more than two consecutive 0 predetermined signals before becoming deactivated.
While the sub-routine of Fig. 2 has been described as checking if a channel contains a video signal, in other words a video signal from a third party transmitter, it is envisaged that in certain cases the subroutine may not check if a channel contains a video signal.
It is also envisaged that while the sub-routine of Fig. 2 has been described as checking if there is another channel having a noise level similar to that of the selected channel by comparing the gain control voltage signals of the channels' any Jo other suitable method for determining and comparing the noise levels of the respective channels may be used. It is also envisaged that in certain cases the sub- routine of Fig. 2 may be provided not to check if there is another channel with a noise level similar to that of the selected channel, and in which case the master control unrt would not have the facility to respond to an alternative channel request signal. Furthermore, while the subroutine of Fig. 2 has been described as checking if there is a channel with a noise level similar to that of the selected channel, it is envisaged that the sub-routine could be adapted for checking if there is a channel with a noise level substantially similar to that of the selected channel, for example, within a predetermined range of noise levels around that of the selected channel.

Claims (93)

  1. Claims 1. A video signal transmission system for transmitting a video
    signal from remotely mounted video camera to a vehicle mounted video signal processing unit for display on a vehicle mounted visual display screen, the transmission system comprising a video camera suitable for mounting remotely of the vehicle, a vehicle mountable master control means for controlling transmission of video signals from the video camera to the vehicle mounted signal processing unit, a vehicle mountable master transmitter operable under the control of the master control rheans for transmitting control signals from the master control means to the video camera for controlling operation of the video camera, a vehicle mountable master receiver for receiving video signals from the video camera, the master receiver having at least two selectable channels for receiving video signals from the video camera, the channels being selectable by the master control means, the master receiver comprising an amplifier, and a gain control means for controlling the gain of the amplifier for amplifying signals on the respective channels to a predetermined power level, a slave control means associated with the video camera for operating the video camera in response to the control signals received from the master control means, a slave receiver associated with the video camera for receiving the control signals from the master control means transmitted by the master transmitter for relaying to the slave control means, and a slave transmitter associated with the video camera for transmitting video signals therefrom to the master control means, the slave transmitter having at least two selectable channels on which video signals from the video camera are transmittable, the frequencies of the respective channels of the slave transmitter corresponding to the frequencies of the respective channels of the master receiver, the master control means comprising: s0 a first selecting means for sequentially selecting at least some of the channels of the master receiver, a reading means for reading respective gain signals from the gain control means of the master receiver indicative of the amplification factors by which signals on the respective selected channels are amplified to bring the signals thereon to the predetermined power level for determining the noise level on the selected channels, and s a second selecting means responsive to the gain signals read by the reading means for selecting the channel of the slave transmitter and the master receiver on which the video signals are to be communicated from the video camera to the master control means, the master control means being responsive to the second selecting means selecting the channel, for setting the master receiver to the selected channel, and for outputting a channel select signal through the master transmitter to the slave control means, the channel select signal indicating the identity of the channel of the slave transmitter which is to be selected by the slave control means for transmitting the video signals from the video camera to the master control means, and the slave control means is responsive to the channel select signal for setting the slave transmitter to the selected channel
  2. 2. A video signal transmission system as claimed in Claim 1 in which the second selecting means is responsive to the gain signals for selecting the channel of the master transmitter, the gain signal for which is indicative of one of the higher JO amplification factors.
  3. 3. A video signal transmission system as claimed in Claim 1 or 2 in which the first selecting means is operable under the control of the master control means for sequentially selecting the at least some of the channels of the master receiver for z determining the noise levels thereon when the slave transmitter is not transmitting.
  4. 4. A video signal transmission system as claimed in any preceding clain' in which the reading means is operable under the control of the master control means for reading signals on the channels of the master receiver selected by the first selecting means for determining if any of the selected channels contain a video signal.
  5. S. A video signal transmission system as claimed in Claim 4 in which the second selecting means is responsive to the reading means and the gain signals for selecting the channel of the master receiver which does not contain a video signal and the signal on which is amplified by the amplification factor which is highest of the amplification factors of the selected channels which do not contain a video signal.
  6. 6, A video signal transmission system as claimed in any preceding claim in which the first selecting means is operable under the control of the master control means in response to an externally generated video activation signal inputted to the to master control means for activating the video camera.
  7. 7. A video signal transmission system as chinned in any preceding claim in which the slave control means is responsive to the channel select signal for activating the video camera to commence operation.
  8. 8. A video signal transmission system as claimed in any preceding claim in which the first selecting means is operable under the control of the master control means for sequentially selecting all of the channels of the master receiver.
  9. 9. A video signal transmission system as claimed in any preceding claim in which the signals on the selected channels of the master receiver when the channels are being sequentially selected by the first selecting means is ideally noise.
  10. 10. A video signal transmission system as claimed in any preceding claim in Is which a storing means is provided for storing the gain signals for the selected channels cross-referenced with identities of the corresponding channels.
  11. 11. A video signal transmission system as claimed in Claim 10 when dependent on Claim 4 in which the storing means stores the identities of the selected channels which contain a video signal.
  12. 12. A video signal tranernission system as claimed in Claim 10 or 11 in which the master control means is responsive to an externally generated alternative channel request signal for selecting a channel the gain signal of which is indicative of an amplification factor, the value of which is substantially singular to that of the selected channel of the master receiver and the slave transmitter,
  13. 13. A video signal transmission system as claimed in Claim 12 in which the nnaster control means is responsive to the externally generated alternative channel request signal only when the master receiver is receiving video signals from the video camera.
  14. 14. A video signal transmission system as claimed in any preceding claim in which the master control means comprises a means for generating a predetermined signal at first predetermined intervals for transmission through the master transmitter to the slave control means after the channel select signal has been transmitted to the slave control means, and the slave control means is responsive to the absence of reception of the predetermined signal for deactivating the video camera.
  15. 15. A video signal transmission system as claimed in Claim 14 in which the slave control means is responsive to the absence of each of the predetermined signals during a period corresponding to a predetermined number of the first predetermined intervals for deactivating the video camera.
  16. 16. A video signal transmission system as claimed in Claim 15 in which the slave control means is responsive to the absence of each of the predetermined signals during a period corresponding to the predetermined number of the first predetermined intervals plus a predetermined safety time period for deactivating the video camera.
  17. 17. A video signal transmission system as claimed in Claim 16 in which the an safety time period is in the range of one second to ten seconds.
  18. 18. A video signal transmission system as claimed in Claim 16 or 17 in which the safety time period is in the range of three seconds to seven seconds.
  19. 19. A video signal transmission system as claimed in any of Claims 16 to 18 in which the safety time period is approximately five seconds.
  20. 20. A video signal transmission system as claimed in any of Claims 15 to 19 in which the predetermined number of the first predetermined intervals does not exceed five first predetermined intervals.
  21. 21. A video signal transmission system as claimed in any of Claims 15 to 20 in which the predetermined number of the first predetermined intervals does not exceed three first predetermined intervals.
  22. 22. A video signal transmission system as claimed in any of Claims 15 to 21 in which the predetermined number of the first predetermined intervals is two first predetermined intervals.
  23. 23. A video signal transmission system as claimed in any of Claims 14 to 22 in which each first predetermined interval is in the range of forty seconds to eighty seconds.
  24. 24. A video signal transmission system as claimed in any of Claims 14 to 23 in which each first predetermined interval is in the range of fiDy-five seconds to sixty- five seconds.
  25. 25. A video signal transmission system as claimed in any of Claims 14 to 24 in which each first predetermined interval is approximately sixty seconds.
  26. 26. A video signal transmission system as claimed in any of Claims 14 to 25 in which the master control means transmits the predetermined signal at the first predetermined intervals in response to reception of the video signal from the video camera.
  27. 27. A video signal transmission system as claimed in any of Claims 14 to 26 in which the master control means is responsive to the absence of reception of the video signal from the video canters far transmitting the predetermined signal at S second predetermined intervals, and the slave control means is responsive to the predetermined signals for reactivating the video camera to transmit the video signal.
  28. 28. A video signal transmission system as claimed in Claim 27 in which each second predetermined interval is in the range of five seconds to twenty-five seconds.
  29. 29. A video signal transmission system as claimed in Claim 28 in which each second predetermined interval is in the range of ten seconds to fifteen seconds.
  30. 30. A video signal transmission system as claimed in Claim 29 in which each Is second predetermined interval is approximately twelve seconds.
  31. 31. A video signal transmission system as claimed in any of Claims 14 to 30 in which the predetermined signal includes the channel select signal.
  32. 32. A video signal transmission system as claimed in any of Claims 14 to 31 in which the slave control means operas the slave receiver for receiving the predetermined signals.
  33. 33. A video signal transmission system as claimed in any of Claims 14 to 32 in as which the master control means operates the master transmitter for transmitting the predetermined signal on a predetermined channel.
  34. 34. A video signal transmission system as claimed in Claim 33 in which the slave control means operates the slave receiver for receiving the predetermined signal on so a channel corresponding to the predetermined channel on which the predetermined signal is being transmitted by the master transmitter.
  35. 35. A video signal transmission system as claimed in any preceding claim in which the master transmitter is a narrow band transmitter.
  36. 36. A video signal transmission system as claimed in Claim 35 in which the slave receiver is a narrow band receiver, and the slave control means sweeps the slave receiver through frequency channels corresponding to the frequency channels of the narrow band receiver for determining the channel on which the predetermined signal is being transmitted by the master transmitter.
  37. 37. A video signal transmission system as claimed in any preceding claim in which the video camera comprises a light source for projecting light to an area being videoed by the video camera.
  38. 38. A video signal transmission system as claimed in Claim 37 in which the light source is provided by at least one light emitting diode.
  39. 39. A video signal transmission system as claimed in Claim 37 or 38 in which the light source is provided by a plurality of light emitting diodes.
  40. 40. A video signal transmission system as claimed in Claim 38 or 39 in which each light transmitting diode outputs light with a relatively high infrared content.
  41. 41. A video signal transmission system as claimed in any of Claims 37 to 40 in which the slave control means is responsive to the channel select signal for us activating the light source when the video camera is being activated.
  42. 42. A video signal transmission system as claimed in any preceding claim in which the master control means is responsive to video signals being received by the master receiver for relaying the video signals to the vehicle mounted video signal processing unit.
  43. 43. A video signal transmission system as claimed in Claim 42 in which the master control means is responsive to video signals being received by the master receiver for relaying the video signals to the signal processing unit so that an image resulting from the video signal when displayed on the visual display screen is presented in an orientation corresponding to the image which would appear in a rear s view mirror of a vehicle.
  44. 44. A video signal transmission system for transmitting a video signal from a remotely mounted video camera to a vehicle mounted video signal processing unit for display on a vehicle mounted visual display screen, the video signal trarmission lo system being substantially as described herein with reference to and as illustrated in the accompanying drawings.
  45. 45. A method for transmitting a video signal from a remotely mounted video camera to a vehicle mounted video signal processing unit for display on a vehicle mounted visual display screen, the method comprising the steps of: providing a video camera suitable for mounting remotely of the vehicle, providing a vehicle mountable master control means for controlling transmission of video signals from the video camera to the vehicle mounted signal processing unit, providing a vehicle mountable master transmitter operable under the control of the master control means for transmitting control signals from the master control means to the video camera for controlling operation of the video camera, providing a vehicle mountable master receiver for receiving video signals from the video camera, the master receiver having at least two selectable channels 2s for receiving video signals from the video camera, the channels being selectable by the master control means, the master receiver being provided with an amplifier and a gain control means for controlling the gain of the amplifier for amplifying signals on the respective channels to a predetermined power level, providing a slave control m. eans associated with the video camera for so operating the video camera in response to the control signals received from the master control means, providing a slave receiver associated with the video camera for receiving the ( control signals from the master control means transmitted by the master transmitter for relaying to the slave control means, providing a slave transmitter associated with the video camera for transmitting video signals therefrom to the master control means, the slave transmitter having at least tNO selectable channels on which video signals frond the video camera are transmittable, the frequencies of the respective channels of the slave transmitter corresponding to the frequencies of the respective channels of the master receiver, providing the nester control means with a first selecting means for to sequentially selecting at least some of the channels of the master receiver, a reading means for reading respective gain signals from the gain control means of the master receiver indicative of the amplification factors by which signals on the respective selected channels are amplified to bring the signals thereon to the predetermined power level for determining the noise level on the selected channels. and a second selecting means responsive to the gain signals read by the reading means for selecting the channel of the slave transmitter and the master receiver on which the video signals are to be communicated from the video camera to the master control means, the master control means being responsive to the second selecting means selecting the channel, for setting the master receiver to the selected channel, and for outputting a channel select signal through the master transmitter to the slave control means, the channel select signal indicating the identity of the channel of the slave transmitter which is to be selected by the slave control means for transmitting the video signals from the video camera to the master control means, and the slave control means is responsive to the channel select signal for selecting the channel of the slave transmitter, the method further comprising the steps of: operating the first selecting means for sequentially selecting at least some of the channels of the master receiver, operating the reading means for reading respective gain signals from the gain control means of the master receiver indicative of the amplification factors by which signals on the respective selected channels are amplified to bring the signals thereon to the predetermined power level, operating the second selecting neans to be responsive to the reading means for selecting the channel of the slave transmitter and the master receiver on which the video signals are to be communicated from the video camera to the master control means, operating the master control means in response to the second selecting means selecting the channel for setting the master receiver to the selected channel, and for outputting a channel select signal from the master transmitter to the slave control means for indicating the identity of the channel of the slave transmitter which is to be selected for transmitting the video signal from the video camera to the master control means, and operating the slave control means in response to the channel select signal for setting the channel of the slave transmitter.
  46. 46. A method as claimed in Claim 45 in which the second selecting means is operated to be responsive to the gain signals for selecting the channel of the master transmitter, the gain signal for which is indicative of one of the higher amplification factors.
  47. 47. A method as claimed in Claim 45 or 46 in which the first selecting means is operated under the control of the master control means for sequentially selecting the at least some of the channels of the master receiver for determining the noise levels thereon when the slave transmitter is not transmitting.
  48. 48. method as claimed in any of Claims 45 to 47 in which the reading means is 2s operated under the control of the master control means for reading the signals on the selected channels of the master receiver selected by the first selecting means for determining if any of the selected channels contain a video signal.
  49. 49. A method as claimed in Claim 48 in which the second selecting means is operated to be responsive to the reading means and the gain signals for selecting the channel of the master receiver which does not contain a video signal and the signal on which is amplified by the amplification factor which is highest of the amplification factors of the selected channels which do not contain a video signal
  50. 50. A method as claimed in any of Claims 45 to 49 in which the first selecting means is operated under the control of the master control means in response to an externally generated camera activation signal inputted to the master control means for activating the video camera.
  51. 51. A method as claimed in any of Claims 45 to 50 in which the slave control means is operated in response to the channel select signal for activating the video lo camera to commence operation.
  52. 52. A method as claimed in any of Claims 45 to 51 in which the first selecting means is operated under the control of the master control means for sequentially selecting all of the respective channels of the master receiver.
    IS
  53. 53. A method as claimed in any of Claims 45 to 52 in which the signals on the selected channels of the master receiver when the channels are sequentially selected by the first selecting means is ideally noise.
    JO
  54. 54. A method as claimed in any of Claims 45 to 53 in which the gain signals for the selected channels are stored in a storing means and crossreferenced therein with identities of the corresponding channels.
  55. 55. A method as claimed in Claim 54 when dependent on Claim 49 in which the 2S identities of the selected channels which contain a video signal are stored in the storing means.
  56. 56. A method as claimed in Claim 54 or 55 in which the second selecting means is operated in response to an externally generated alternative channel request signal for selecting a channel of the master receiver, the gain signal of which is indicative of an amplification factor, the value of which is similar or substantially similar to that of the selected channel of the master receiver and the slave transmitter.
  57. 57. A method as claimed in any of Claims 45 to 56 in which a means is provided for generating a predetermined signal at first predetermined intervals for transmission through the master transmitter to the slave control means after the channel select signal has been transmitted to the slave control means, and the slave control means is operated in response to the absence of reception of the predetermined signal for deactivating the video camera.
  58. 58 A method as claimed in Claim 57 in which the slave control means is operated to be responsive to the absence of each of the predetermined signals during a time period corresponding to a predetermined number of the first predetermined intervals for deactivating tine video camera.
  59. 59. A method as claimed in Claim 58 in which the slave control means is operated to be responsive to the absence of each of the predetermined signals during the period of the predetermined number of the first predetermined intervals plus a predetermined safety time period for deactivating the video camera.
  60. 60. A method as claimed in Claim 59 in which the safety time period lies in the To range of one second to ten seconds.
  61. 61. A method as claimed in Claim 59 or 60 in which the safety time period lies in the range of three seconds to seven seconds.
  62. 62. A method as claimed in any of Claims 59 to 61 in which the safety time period is approximately five seconds.
  63. 63. A method as claimed in any of Claims 58 to 63 in which the predetermined number of the first predetermined intervals does not exceed five first predetermined intervals
  64. 64. A method as claimed in any of Claims 58 to 63 in which the predetermined number of the first predetermined intervals does not exceed three first predetermined intervals.
  65. 65. A method as claimed in any of Claims 58 to 64 in which the predetermined number of the first predetermined intervals is two first predetermined intervals.
  66. 66. A method as claimed in any of Claims 57 to 65 in which each first predetermined time interval lies in the range of forty seconds to eighty seconds.
    t0
  67. 67. A method as claimed in any of Claims 57 to 66 in which each first predetermined time interval lies in the range of ffty-five seconds to sixty-five seconds.
  68. 68. A method as claimed in any of Claims 57 to 67 in which each first predetermined time interval is approximately sixty seconds.
  69. 69. A method as claimed in any of Claims 57 to 68 in which the master control means is responsive to the reception of the video signals from the video camera for transmitting the predetermined signal at Me first predetermined intervals.
  70. 70. A method as claimed in any of Claims 57 to 69 in which the master control means is responsive to the absence of reception of the video signal from the video camera for transmitting the predetermined signal at second predetermined intervals, and the slave control means is responsive to the predetermined signals for 2s reactivating the video camera to transmit the video signals.
  71. 71. A method as claimed in Claim 70 in which each second predetermined interval lies in the range of five seconds to twenty-five seconds.
  72. 72. A method as claimed in Claim 71 in which each second predetermined interval lies in the range of ten seconds to fifteen seconds.
  73. 73. A method as claimed in Claim 72 in which each second predetermined interval is approximately twelve seconds.
  74. 74. A method as claimed in any of Claims 57 to 73 in which the predetermined signal includes the channel select signal.
  75. 75. A method as claimed in any of Claims 57 to 74 in which the slave control means operates the slave receiver for receiving the predetermined signals.
  76. 76. A method as claimed in any of Claims 57 to 75 in which the master control means operates the master transmitter for transmitting the predetermined signal on a predetermined channel.
  77. 77. A method as claimed in Claim 76 in which the slave control means operates IS the slave receiver for receiving the predetermined signals on a channel corresponding to the predetermined channel on which the predetermined signal is being transmitted by the master transmitter.
  78. 78. A method as claimed in any of Claims 57 to 77 in which the master transmitter is provided as a narrow band transmitter, and the slave receiver is provided as a narrow band receiver, and the slave receiver is operated under the control of the slave control means for sweeping the receiving frequency of the slave receiver through frequency channels corresponding to the frequency channels of the slave receiver for determining the channel on which the predetermined signal is 2s being transmitted by the master transmitter.
  79. 79 A method as claimed in any of Claims 45 to 78 in which a light source is provided in the video camera for lighting an area being videoed by the video camera.
    JO
  80. 80. A method as claimed in any of Claims 45 to 79 in which the video signals received by the master receiver are relayed by the master control means to the vehicle mounted video signal processing unit.
  81. 81. A method as claimed in any of Claims 45 to 80 in which the video signals are relayed to the vehicle mounted video signal processing unit such that the image displayed on the visual display screen is oriented in an orientation similar to that in S which the image would appear in a rear view mirror of the vehicle.
  82. 82 A method for transmitting a video signal from a remotely mounted video camera to a vehicle mounted video signal processing unit for display on a vehicle mounted visual display screen, the method being substantially as described herein with reference to and as illustrated in the accompanying drawings.
  83. 83. A video camera for use in the video signal transmission system as claimed in any of Claims 1 to 44, the video camera comprising a housing having a hollow interior region, a main printed circuit board located in the hollow interior region, a IS video camera unit mounted on the main printed circuit board within the hollow interior region, a secondary printed circuit board located within the hollow interior region, the secondary printed circuit board being electrically coupled to the main ponted circuit board, a locating means for locating the main and secondary printed circuit boards relative to each other for facilitating electrical coupling thereof, and an alignment means Or facilitating correct alignment and location of the main and secondary printed circuit boards within the hollow interior region of the housing.
  84. B4. A video camera as claimed in Claim 83 in which a main guide track is provided for receiving the main printed circuit board in the hollow interior region of 2s the housing.
  85. 85. A video camera as claimed in Claim 83 or 84 in which a secondary guide track is provided for receiving the secondary printed circuit board in the hollow interior region of the housing.
  86. 86. A video camera as claimed in any of Claims 83 to 84 in which an
    opening is provided in the secondary printed circuit board for accommodating the video camera unit from the main printed circuit board therethrough.
  87. 87. A video camera as claimed in Claim 86 in which the locating means comprises a key formed on one of the video camera unit and the secondary printed circuit boarel, and a key-way formed on the other of the video camera unit and the secondary printed circuit board for co-operating with the key for locating the main and secondary printed circuit boards relative to each other.
  88. 88. A video camera as claimed in any of Claims 83 to 87 in which the alignment means comprises an alignment projection extending from one of the housing and the secondary printed circus board' and an alignment recess formed in the other of the housing and the secondary printed circuit board for co-operating with the alignment projection for correctly aligning and locating the main and secondary printed circuit boards in the hollow interior region of the housing.
  89. 89. A video camera as claimed in any of Claims 83 to 88 in which a main lens is provided in the housing aligned with the video camera unit when the main and secondary printed circuit boards are correctly aligned and located in the hollow interior region of the housing.
  90. 90. A video camera as claimed in any of Claims 83 to 89 in which a light source is provided on the secondary printed circuit board for lighting an area being videced by the video camera.
  91. 91. A video camera as claimed in Claim 90 in which a plurality of light sources are located on the secondary printed circuit board.
  92. 92. A video camera as claimed in Claim 90 or 91 in which a secondary lens is provided in the housing corresponding to each light source for accommodating light from the corresponding light source therethrough.
  93. 93. A video camera for use in the video signal transmission system as claimed in any of Claims 1 to 44, the video camera being substantially as described herein with reference to and as illustrated in the accompanying drawings.
GB0512737A 2004-06-22 2005-06-22 A video signal transmission system and method Active GB2415568B (en)

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IE20040426A IES20040426A2 (en) 2004-06-22 2004-06-22 A video signal transmission system, and a method for transmitting a video signal from a remotely mounted video camera to a vehicle mounted video signal processing unit

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008072035A1 (en) * 2006-12-14 2008-06-19 Freescale Semiconductor, Inc. Transmission and reception channel selection for communicating between a transmitter unit and a receiver unit
US20110181736A1 (en) * 2010-01-27 2011-07-28 Elmo Company, Limited Presentation device
US9637051B2 (en) 2006-01-20 2017-05-02 Winplus North America, Inc. System for monitoring an area adjacent a vehicle

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114153314B (en) * 2021-11-29 2023-04-25 重庆长安汽车股份有限公司 In-vehicle noise dynamic display interaction method and system for enhancing user experience

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4980924A (en) * 1986-11-19 1990-12-25 Plessey Overseas Limited HF radio communication systems with frequency management
US5943340A (en) * 1996-02-02 1999-08-24 Nec Corporation Channel assignment controlling system
US6028625A (en) * 1995-07-19 2000-02-22 Cannon; Michael W. Examination system for architectural structure exteriors
JP2001224010A (en) * 2000-02-08 2001-08-17 Mitsubishi Electric Corp Monitor camera system
US20020093565A1 (en) * 1998-07-22 2002-07-18 Watkins D. Scott Headrest and seat video imaging apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4980924A (en) * 1986-11-19 1990-12-25 Plessey Overseas Limited HF radio communication systems with frequency management
US6028625A (en) * 1995-07-19 2000-02-22 Cannon; Michael W. Examination system for architectural structure exteriors
US5943340A (en) * 1996-02-02 1999-08-24 Nec Corporation Channel assignment controlling system
US20020093565A1 (en) * 1998-07-22 2002-07-18 Watkins D. Scott Headrest and seat video imaging apparatus
JP2001224010A (en) * 2000-02-08 2001-08-17 Mitsubishi Electric Corp Monitor camera system

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9637051B2 (en) 2006-01-20 2017-05-02 Winplus North America, Inc. System for monitoring an area adjacent a vehicle
US11603042B2 (en) 2006-01-20 2023-03-14 Adc Solutions Auto, Llc System for monitoring an area adjacent a vehicle
WO2008072035A1 (en) * 2006-12-14 2008-06-19 Freescale Semiconductor, Inc. Transmission and reception channel selection for communicating between a transmitter unit and a receiver unit
US8942186B2 (en) 2006-12-14 2015-01-27 Freescale Semiconductor, Inc. Transmission and reception channel selection for communicating between a transmitter unit and a receiver unit
US20110181736A1 (en) * 2010-01-27 2011-07-28 Elmo Company, Limited Presentation device

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GB0512737D0 (en) 2005-07-27
GB2415568B (en) 2010-04-21
IE20050421A1 (en) 2005-12-29
IES20040426A2 (en) 2005-11-02

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