Luggage door unlocking device for a vehicle

A luggage door unlocking device for a vehicle, comprising:

• (1) a portable transmitter which comprises a case and a transmitting means for generating an unlocking signal having an ultrasonic frequency, said transmitting means being supported by said case and comprising a power source, a pulse train generating circuit for generating a high-frequency pulse train of a predetermined pattern, an ultrasonic wave transmitter which generates an unlocking signal of ultrasonic frequency in response to said high-frequency pulse train, a power supply switch interposed between said pulse train generating circuit and said power source, and a power supply switch driving circuit for driving said power switch;
• (2) a receiving means mounted on the vehicle and comprising an ultrasonic wave receiver for receiving an ultrasonic signal from the outside of the vehicle, a discriminating means for discriminating the signal received by said receiver to obtain said unlocking signal, a signal processing means for transmitting an ultrasonic signal out of the vehicle and processing the signal received by said receiver, and a switching means for connecting said ultrasonic wave receiver to said discriminating means when said vehicle is not operating and for connecting said ultrasonic wave receiver to said signal processing means when the vehicle is operating;
• and
• (3) an unlocking means mounted on the vehicle for operating a luggage door unlocking mechanism of the vehicle upon receipt of said unlocking signal after discrimination by said discriminating means;
• said portable transmitter being further provided with a retaining means for attaching said case to a part of the clothes of a person who carries the portable transmitter, said retaining means being mounted on the outer surface of said case and having a switch contact connected to said power supply switch driving circuit said retaining means being adapted to open and close in response to the attaching and detaching operation of said retaining means and generating a signal for driving said power supply switch.