Importance

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Abstract

A keyless entry system can lock and unlock an automotive vehicle door, a trunk lid, a glove box and/or a steering column without an ignition key. The system comprises a transmitter producing a radio signal indicative of a preset unique code, and a controller receiving the radio signal and performing desired locking or unlocking operation when the code from the transmitter matches a preset code. A manual switch is provided to order the transmitter to transmit the code-indicative radio signal to the controller. The transmitter encloses a battery acting as a power source. Locking the transmitter in the vehicle is detected by detecting that the code signal level remains substantially unchanged for a given period of time after the vehicle is locked. In such cases, an alarm is produced to remind the driver to remove the transmitter from the vehicle cabin by operating the manual switch to open the door. An optional feature disables the keyless entry system if the driver fails the retrieve the transmitter after the alarm.

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First Claim