Abstract:
The remote control switch apparatus has an instruction switch provided on a steering wheel to project toward the inside of a passenger compartment away from an instrument panel of the car so as to indicate a driving condition. A transmitter is installed at the steering wheel to generate a radio wave signal or radiation signal in response to the instruction switch and a receiver, provided on the instrument panel, receives the radiation signal and generates a control signal.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a switch apparatus for automobiles suitable for use in, for example, setting, releasing and so on of a constant speed driving control apparatus. 
     In general, such switches for automobiles are a horn switch provided on the top surface of the steering wheel, switches on a steering column (outer cover portion of the steering support) and switches on the instrument panel. However, it is desirable that the switches be operated while the car is being driven, such as those for the constant speed driving apparatus, can be operated by the driver&#39;s hand which touches and operates the steering wheel, and that the switches are provided at a position where they can be seen in a moment. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a switch apparatus for automobiles which meets the above requirements. 
     It is another object of the invention to provide a switch apparatus for automobiles which can be installed without use of additional electrical wiring. 
     In order to achieve the above objects, the apparatus of the invention is formed such that electrical switches are provided on the top surface of a movable steeing wheel and the signals from the switches are transmitted on a radio wave signal or radiation signal to a fixed member in the trim of the passenger compartment. 
     Moreover, electrical power is fed to the electrical switches and the signal transmitter by making use of the conventionally provided horn switch, with a simpler wiring being expected. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an electrical connection diagram of one embodiment of the switch apparatus according to the invention. 
     FIG. 2 is a perspective view of the arrangement of components in the embodiment. 
     FIG. 3 is an electrical connection diagram of the power supply circuit for a transmitter 2 as shown in FIG. 1. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     One embodiment of the invention will be described hereinafter with reference to the accompanying drawings. Referring to the electrical connection diagram of the whole arrangement of FIG. 1, there are shown plural switches of a driving condition setting switch 1, and a transmitter 2, which includes an integrated circuit 201 for remotely controlling the transmitter (M58480, made by the Mitsubishi Electric Co.) a discrete ceramic resonator circuit 202 for generating a reference oscillation, a buffer circuit 203 (four CD4049 circuits made by RCA) and an ultrasonic wave transmitter 204 (EFR-OTB40K2, made by the Matsushita Electronic Component Co.). A signal from the setting switch 1 in response to operation thereof is applied to the integrated circuit 201 in the transmitter 2. This circuit 201 then produces a single-line multiplex communication signal such as a serial multiplex signal corresponding to the operation status of the switch of the setting switch 1, depending on the reference oscillation signal from the discrete ceramic resonator circuit 202, and supplies it through the buffer circuit 203 to the ultrasonic transmitter 204. The ultrasonic transmitter 204 emits this single-line multiplex communication signal as an ultrasonic wave. 
     The ultrasonic wave signal emitted from the transmitter 2 is received by an ultrasonic wave receiver 301 (RTB40K2, made by the Matsushita Electronic Component Co.) in a receiver 3, and converted to the associated electrical signal. The electrical signal from the ultrasonic wave receiver 301 is applied through a waveform shaping circuit 302 having an AC coupling capacitor and a comparator, and through an input circuit 303 of an AC coupling capacitor, to an integrated circuit 304 for a remotely controlled receiver (M58481, made by the Mitsubishi Electric Co.). This integrated circuit 304 is responsive to the single-line multiplex communication signal to produce parallel signals at terminals P 0 , P 1  and P 2  by the application of a reference oscillation signal from a discrete ceramic resonator circuit 305. The signals appearing at the terminals P 0 , P 1  and P 2  become high &#34;H&#34; level by closing the respective switches of the setting switch 1, but are not released to the low &#34;L&#34; level by opening the respective switches thereof. Therefore, the combination of a CR oscillation circuit 306, a binary frequency dividing circuit (CD4040, made by RCA) 307, a 3-input NOR gate 308 and a transistor switching circuit 309 is used to prevent the above situation. That is, when any one of the terminals P 0 , P 1  and P 2  becomes high, &#34;H&#34; level, the switching circuit 309 makes a short circuit between terminals I 1  and φ D  of the integrated circuit 304, and thereby after a certain time, changes this signal from the &#34;H&#34; level to &#34;L&#34; level. Reference numeral 310 represents a transistor switching circuit for converting the signals produced at the terminals P 0 , P 1  and P 2  to switching signals, 311 an operation switch of the receiver 3, and 312 a capacitor for automatic resetting upon turning on of power supply. 
     Reference numeral 4 designates an electrical equipment such as a constant speed running control apparatus or the like for being responsive to a signal which is associated with the setting switch 1 and generated from the receiver 3. 
     FIG. 2 shows the arrangement of the respective blocks in this embodiment. On the panel of the transmitter 2 is disposed the setting switch 1, above which is located the ultrasonic transmitter 204 to emit an ultrasonic signal toward the instrument panel surface. The setting switch 1 and the transmitter 2 are installed around the center of a rotatable steering wheel 5. Reference numeral 6 represents a horn switch. In addition, the receiver 3 spaced from and located behind the ultrasonic receiver 301 opposing the ultrasonic wave transmitter 204 is disposed on an instrument panel 7 in front of the steering wheel 5. 
     FIG. 3 is an electrical connection diagram of the power supply circuit of the transmitter 2. When the horn switch 6 is opened, a battery 13 in the car supplies current through the terminals of a horn relay 12 of the horn switch 6 and through a diode 14 to a capacitor 15 to charge the capacitor 15. The voltage across the capacitor 15 is supplied via a Zener diode constant voltage circuit 16 to the transmitter 2 as a constant voltage. Therefore, even though the horn switch 6 is closed, the accumulated charge in the capacitor 15 enables the transmitter 2 to operate. Numeral 17 denotes a horn which is activated by the closure of the switch 6. 
     As will be obvious from the above description, when the setting switch 1 located on the steering wheel 5 is operated, an ultrasonic wave signal emitted from the transmitter 2 is received by the receiver 3 and applied to the electrical equipment 4 as an electrical signal associated with the operation of the setting switch 1. If the transmitter 2 is separated several tens of centimeters from the receiver 3, a directivity of several tens of degrees can be obtained. So the transmission of the signal therebetween is possible even under a certain amount of angular movement of the steering wheel 5. 
     While ultrasonic waves are used for the wireless transmitting and receiving system as described above, any coupling means such as a photo coupler of a light emitting diode and a photo transistor, and a magnetic coupling means may be utilized unless wireless transmission and reception is possible. Moreover, the number of receiving elements may be increased for widening the directivity or transmissible space range as necessary. 
     Thus, since the apparatus of the invention has the switch provided on the steering wheel, not on the instrument panel as seen in the prior art, the driver can readily operate the switch without stretching his hand thereto.