Abstract:
A cancel switch is intended for use with a vehicle equipped with an audiovisual system having a compulsory switching unit which compulsorily switches a video on a monitor screen to a still image or a navigation screen during a running condition of the vehicle. The cancel switch includes a deactivation unit deactivating the compulsory switching unit so that the video is displayed even during the running condition of the vehicle. The deactivation unit includes a proximity sensor which detects proximity of an object by a non-contact manner and a switching circuit which conducts or breaks a signal line through which a determination signal indicative of the running condition of the vehicle is transmitted.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a U.S. national stage application of PCT/JP2008/066703 filed on Sep. 17, 2008 and is based on and incorporates herein by reference Japanese Patent Application No. 2008-237337 filed on Sep. 17, 2008. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a cancel switch for a vehicle-mounted audiovisual system provided with a compulsory switching unit which compulsorily switches a video on a monitor screen to a still image or a navigation screen during a running condition of a vehicle, and more particularly to such a cancel switch provided with a deactivation unit which deactivates the compulsory switching unit of the audiovisual system so that the video is displayed even during the running condition of the vehicle. 
       RELATED ART 
       [0003]    A vehicle-mounted audiovisual system (hereinafter, “vehicle-mounted AV system”) such as vehicle-mounted televisions, car-navigation systems, vehicle-mounted DVD reproducers, etc. generally has a function of limiting video display by forbidding video display on a monitor screen or by compulsorily switching the video display to a still image or a navigation screen such as a load map while a vehicle is in a running condition, from a standpoint of prevention of accidents such as inattentive driving. 
         [0004]    Japanese Utility Model Registration No. JP-Y-3102335 discloses a control device provided for a vehicle-mounted television which is configured not to display a television program on air during a running condition of the vehicle. The control device allows the vehicle-mounted television to display the television program even during the running of the vehicle with consideration to safe driving. 
         [0005]    The control device comprises a device body having a switching portion and a control portion and an operation switch which is detachably attachable to the control portion of the device body thereby to control the operation of the device body. The switching portion is provided with at least one selector switch which switches between a first state where a control signal indicative of whether or not the vehicle is running is supplied to the vehicle-mounted television and a second state which indicates that the vehicle is parked by cutting off the control signal or by another means. 
         [0006]    The device body and the operation switch of the aforementioned control device are often attached to a front panel of dashboard, a console or the like which is reachable from a driver&#39;s seat or passenger&#39;s seat, by screws or double-sided tape. However, car design has recently employed curved surfaces, and the dashboard or the like has often employed a design composed of curved surfaces. Accordingly, it is difficult to ensure a mounting location for the aforesaid control device as a customer/user installed parts/options. 
         [0007]    Furthermore, the device body or the operation switch attached by a double-sided tape is detached when the aforesaid control device is replaced by another or when the vehicle on which the aforesaid control device is provided is relinquished for trade-in or the like. In this case, a mark resulting from the use of the double-sided tape is sometimes left on the dashboard. It is difficult to remove the mark thereby to restore the dashboard to an original state thereof. 
         [0008]    Furthermore, a sunburn mark is sometimes formed along a contour of the device body or the operation switch on the mounting location since the dashboard on which the device body and the operation switch are mounted is subjected to sunlight. The sunburn mark differs in the color tone from a part of the dashboard around the sunburn mark and is difficult to remove such that the dashboard cannot be restored to the original state thereof. 
         [0009]    Additionally, a lead wire connecting between the device body and the vehicle-mounted television or the like is exposed when the device body is mounted so as to be exposed in the vehicle interior. A lead wire connecting between the operation switch and the device body is exposed when the operation switch is mounted so as to be exposed in the vehicle interior. As a result, a hand or a finger is caught by the exposed lead wire, which has a possibility of interfering with a driving operation of the driver. 
       SUMMARY 
       [0010]    Therefore, an object of the present invention is to provide a cancel switch which can be provided on a backside of the dashboard or a panel forming the console by the use of a proximity sensor thereby to prevent the interference with the driving operation of the driver. 
         [0011]    The present invention provides a cancel switch for use with a vehicle equipped with an audiovisual system provided with a compulsory switching unit which compulsorily switches a video on a monitor screen to a still image or a navigation screen during a running condition of the vehicle, the cancel switch comprising a deactivation unit deactivating the compulsory switching unit so that the video is displayed even during the running condition of the vehicle, wherein the deactivation unit includes a proximity sensor which detects proximity of an object by a non-contact manner and a switching circuit which conducts or breaks a signal line through which a determination signal indicative of the running condition of the vehicle is transmitted. 
         [0012]    According to the cancel switch described in claim  1 , proximity of the object is detected by the proximity sensor, and the determination signal line with respect to the running condition of the vehicle is conducted or broken by the switching circuit. The proximity sensor can be mounted on the backside of a plastic panel constituting a vehicle body interior such as a front panel or a console in the vehicle interior. Accordingly, the cancel switch can be disposed on the backside of the panel forming the dashboard or the console. Consequently, the vehicle interior can be prevented from being changed even when the cancel switch is provided, whereby the unity of the design can be maintained. 
         [0013]    Furthermore, since the cancel switch is disposed in the backside of the panel, an operating portion of the switch and a lead wire connecting between the operating portion and the switch body are not exposed in the vehicle interior. Accordingly, the driving operation can be prevented from interference since a hand or a finger is prevented from being by the operating portion and/or the lead wire. 
         [0014]    In one embodiment, the proximity sensor is of a capacitance type. The object to be detected can be a nonmetal such as a hand or a finger since the proximity sensor is of a capacitance type. Accordingly, the switching circuit can easily be switched simply by holding the hand or the finger over a detecting portion of the proximity sensor. 
         [0015]    In another embodiment, the switching circuit comprises a relay circuit. Consequently, the switching circuit can easily be arranged when comprising a relay circuit. 
         [0016]    In further another embodiment, when the signal line through which the determination signal is being transmitted is conducted or cut off by the switching circuit, the switching circuit is maintained in the conducting state or the breaking state until the deactivation unit is subsequently operated. The cancel switch is configured into a self-maintaining type in which the switching circuit maintains the on-state or the off-state until subsequently operated. Consequently, the cancel switch can be turned on or off every time the hand or the finger is brought closer to the proximity sensor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a perspective view of the cancel switch according to an embodiment, showing a schematic configuration of the cancel switch; and 
           [0018]      FIG. 2  is a schematic block diagram showing a circuit arrangement of the cancel switch. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    An embodiment of the cancel switch in accordance with the present invention will be described with reference to the accompanying drawings.  FIG. 1  shows a schematic structure of the cancel switch and  FIG. 2  is a block diagram showing the schematic circuit arrangement. 
         [0020]    As shown in  FIG. 1 , the cancel switch  10  comprises a cable  13  having one of two ends provided with a first connector  11  and the other end provided with a second connector  12  and a switch body  14  provided in the middle of the cable  13 . The first connector  11  is formed so as to be connectable to a control input/output terminal of a monitor device  100  composing a vehicle-mounted AV system. The second connector  12  is formed so as to be connectable to a vehicle-body side control input/output terminal  110 . The cable  13  is formed by bundling a plurality of signal wires. Additionally, the vehicle-mounted AV system employed in the embodiment is a vehicle-mounted television, a vehicle-mounted theater system or a vehicle-mounted navigation system and includes a monitor device. 
         [0021]    The signal wires composing the cable  13  comprise a power-supply line for the monitor device  100  of the vehicle-mounted AV system, an audio signal line, an image signal line from a car stereo and the like. The switch body  14  is provided in the middle of a determination signal line  15  through which a signal indicative of the determination as to whether or not the vehicle is in a running condition is transmitted. The signal transmitted through the determination signal line  15  is at least one of a global positioning system (GPS) signal, a parking brake signal, a vehicle speed detection signal and the like, all of which can detect whether or not the vehicle is running.  FIG. 1  shows two determination signal lines  15 , that is, a vehicle speed detection signal line  15   a  and a parking brake signal line  15   b.    
         [0022]    The switch body  14  comprises a detecting portion  21  of a proximity sensor  20  and a casing  40  as shown in  FIGS. 1 and 2 . The casing  40  encloses a substrate (not shown) on which are mounted a sensor processing circuit  22  and a relay circuit  30  provided with a relay contact. A ground wire  16  connected to the substrate is drawn out of the casing  40 . 
         [0023]    To the substrate is connected a power supply line  18  having a fuse box  17  provided in the middle thereof. The cancel switch  10  is activated by electric power supplied from a power supply line  18 . A fuse  17   a  having a predetermined rating is enclosed in the fuse box  17 . The power supply line  18  is connected to a body side power supply provided separately from a vehicle body side connector  110 . However, when the cable  13  formed by bundling the signal wires includes a power supply line, electric power may be supplied to the cancel switch  10  via the fuse  17   a  mounted on the substrate enclosed in the casing  40 . 
         [0024]    The sensor processing circuit  22  and the relay circuit  30  constitute a switching circuit  35 . A transmission line  23  connects between the detecting portion  21  of the proximity sensor  20  and the sensor processing circuit  22 . Thus, the detecting portion  21  can be reduced in size and weight since the detecting portion  21  and the casing  40  are formed separately from each other. 
         [0025]    The proximity sensor  20  is of a capacitance type and detects a variation in electric field. The detecting portion  21  has an electrode  24 . A casing of the detecting portion  21  encloses a crystal (CR) oscillation circuit having the electrode  24  and a detection circuit (not shown) comprising an oscillating state detection circuit and an output circuit. A variation in electric field detected by the electrode  24  is delivered as a detection signal via the output circuit of the detection circuit. The detection signal is amplified and rectified by the sensor processing circuit  22  thereby to be converted to a control signal. 
         [0026]    The relay circuit  30  includes at least one switch  31  as shown in  FIG. 2 . The relay circuit  30  mechanically opens or closes relay contacts according to the control signal transmitted from the proximity sensor  20  thereto, thereby breaking or conducting the determination signal line  15 . The switching circuit  35  thus includes the relay circuit  30  switching the relay contacts off and on. However, the switching circuit  35  should not be limited to the above-described arrangement. A semiconductor switching element may be used which comprises a transistor, a field effect transistor (FET), a turn-off thyristor (GTO) or the like. 
         [0027]    The switch body  14  is formed into a self-maintenance type and maintains a switched state when switched between on-state and off-state. As a result, the switch body  14  is maintained in on-state or off-state until subsequently operated. Accordingly, the cancel switch  10  can easily be operated. The screen of the monitor device  100  can be changed among a video image, a still image and a navigation screen every time the cancel switch  10  is operated. 
         [0028]    The following describes the usage of the cancel switch  10  as configured above. The control input/output terminal of the vehicle-mounted AV system is fitted into the first connector  11 , and the control input/output terminal  110  at the body side is fitted into the second connector  12 . The detecting portion  21  of the proximity sensor  20  is thus formed with the electrode  24  in abutment with the backside of the panel  120 . In this case, it is desirable that the electrode  24  be mounted so as to be directed to the surface side of the panel  120 . Furthermore, the casing  40  is mounted to an out-of-side place such as a glove box, the backside of the dashboard or a lower part of driver&#39;s seat or another seat. It is more desirable that the casing  40  be mounted in the vicinity of the detecting portion  21  for the purpose of preventing the transmission line  23  from noise contamination. The panel  120  is an interior decorative material comprising a synthetic resin and constitutes the dashboard, the console or the like. The panel  120  as shown in  FIG. 1  is apart of the dashboard or the like, for example. 
         [0029]    The cancel switch  10  mounted in the above-described manner is activated when a hand or a finger is brought close to the surface side of the panel  120  on which the proximity sensor  20  is mounted. The capacitance of the electrode  24  is increased when an object comes closer to the electrode  24 . The proximity sensor  20  converts a variation in the capacitance of the electrode  24  to a detection signal, delivering the signal. The proximity sensor  20  includes the CR oscillation circuit which starts or stops oscillation according to variations in the capacitance of the electrode  24 . An oscillation signal delivered from the CR oscillation circuit is a detection signal of the proximity sensor  20 . 
         [0030]    Furthermore, a variation of the capacitance becomes larger as a relative permittivity is increased. The relative permittivity of water is about  80  when the relative permittivity is 1 in vacuum. Accordingly, since a capacitance type proximity sensor easily detects an object with a high water content, the proximity sensor  20  can easily detect proximity of human body with a high water content. Hence, it is desirable that a distance between the detecting portion  21  and the object be adjusted so that the proximity sensor  20  is responsive when a hand or a finger is adjacent to an opposite side of the detecting portion  21  with the panel  120  being interposed therebetween or the surface side of the detecting portion  21 . As the result of such adjustment, the proximity sensor  20  can be prevented from malfunction in which the proximity sensor  20  is responsive to a hand or a finger moved in the vicinity of the surface side of the panel  120 . 
         [0031]    When the switch body  14  is switched so that the cancel switch is turned off, the switch  31  of the relay circuit  30  is conducted. In this case, a signal indicative of the running state of the vehicle is delivered. Accordingly, the compulsory switching is executed in which the video displayed by the monitor device  100  is compulsorily switched to a still image or a navigation screen. On the other hand, when the cancel switch is turned on, the switch  31  of the relay circuit  30  is broken or cut off. In this case, since the determination signal line  15  is broken, the above-described compulsory switching is not executed. 
         [0032]    According to the above-described embodiment, the switch body  14  can be operated without touch therewith as the result of employment of the proximity sensor  20 . Accordingly, the cancel switch  10  can be provided at the back surface side of the panel  120  constituting the interior of the vehicle such as the backside of the front panel or the console. Consequently, the cancel switch  10  can be installed without change in the vehicle interior and can be consealed. 
         [0033]    The foregoing description and drawings are merely illustrative of the present disclosure and are not to be construed in a limiting sense. Various changes and modifications will become apparent to those of ordinary skill in the art. All such changes and modifications are seen to fall within the scope of the appended claims.