|국가/구분||United States(US) Patent 등록|
|미국특허분류(USC)||340/426 ; 340/554 ; 367/094|
|발명자 / 주소|
|출원인 / 주소|
|대리인 / 주소||
|인용정보||피인용 횟수 : 4 인용 특허 : 5|
In an entering detecting system for vehicles, a received ultrasonic signal is amplified by an amplifier circuit so that a Doppler signal may be generated from an amplified signal and a transmission signal for detecting an entering of unauthorized person into a vehicle compartment. An operational amplifier circuit of the amplifier circuit has an output limiter circuit. The output limiter circuit has diode series circuits which are connected to a feedback resistor of an operational amplifier.
[What is claimed is:] [1.]transmitter means for transmitting an ultrasonic transmission signal into a vehicle compartment;receiver means for receiving as a reception signal the ultrasonic transmission signal reflected in the vehicle compartment;Doppler shift output generating means for generating a Doppler shift signal from the transmission signal and the reception signal;reception signal level detecting means for detecting a level of the reception signal; andchecking means for checking whether the level of the reception signal detected by the detecting ...