| 摘要 |
<p>A keyless entry system allows fully automatic operation of a door lock device of an automotive vehicle. The system recognizes the presence and absence of an authorized user and automatically locks or unlocks the vehicle door lock device according to the presence or absence of the authorized user. The keyless entry system is provided with a controller mounted on a vehicle and designed to periodically generate a radio demand signal and transmit same at regular intervals. A radio code signal transmitter is normally in a stand-by state in which it is ready to transmit a radio code signal indicative of a preset code in response to the radio demand signal. The radio code signal transmitter is of a pocket-portable size for convenient transport by an authorized user. The radio signal transmission between the controller and the radio code signal transmitter is performed within a predetermined distance range around the vehicle. Therefore, the radio code signal transmitter becomes active when the authorized user carrying the same enters into the predetermined radio signal transmission range to transmit the radio code signal to the controller. The controller receives and compares the preset code with a unique code stored in its memory and operates a door lock device for unlocking when the codes match. On the other hand, while the authorized user is output of the radio signal transmission range, the controller detects absence of the radio code signal to operate the door lock device for locking.</p> |
