Keyless entry system for automotive devices antenna device allowing low power radio signal communication
First Claim
1. A keyless entry system comprising:
- a manual switch;
a pocket-portable transmitter transmitting a radio signal indicative of an unique code which identifies the transmitter, in response to a demand in the form of a radio signal;
a receiver/controller means transmitting a demand indicative radio signal to said transmitter in response to operation of said manual switch, receiving said unique code-indicative radio signal from said transmitter, comparing said unique code indicated by the received signal with a preset code, and producing a control signal when said unique code matches said preset code, said receiver/controller means including an antenna device for receiving said unique code-indicative radio signal by electromagnetic induction and having a first segment susceptible to electromagnetic induction and a second segment having substantially lower impedance than said first segment and inductively coupled with said first segment for generating a magnetic field sufficiently intense to cause electromagnetic induction and to transmit said demand indicative radio signal to said transmitter; and
an electrically operable actuator associated with said receiver/controller circuit and with an object device to be operated, and responsive to said control signal to operate said object device to perform a desired operation.
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Accused Products
Abstract
A keyless entry system employs a pocket-portable radio signal transmitter to be carried by a user and a controller mounted on a vehicle and associated with a vehicle device, such as a door lock mechanism, a trunk lid opener, a window regulator, a steering lock device and so forth, to be operated. Radio signal communication between the transmitter and the controller is performed by electromagnetic induction. According to the present invention, electromagnetic induction is caused between antennas in the transmitter and the controller. In order to provide wide communication area, at least the antenna of the controller serves as a transformer to generate higher loop current for generating sufficiently strong magnetic field therearound.
118 Citations
19 Claims
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1. A keyless entry system comprising:
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a manual switch; a pocket-portable transmitter transmitting a radio signal indicative of an unique code which identifies the transmitter, in response to a demand in the form of a radio signal; a receiver/controller means transmitting a demand indicative radio signal to said transmitter in response to operation of said manual switch, receiving said unique code-indicative radio signal from said transmitter, comparing said unique code indicated by the received signal with a preset code, and producing a control signal when said unique code matches said preset code, said receiver/controller means including an antenna device for receiving said unique code-indicative radio signal by electromagnetic induction and having a first segment susceptible to electromagnetic induction and a second segment having substantially lower impedance than said first segment and inductively coupled with said first segment for generating a magnetic field sufficiently intense to cause electromagnetic induction and to transmit said demand indicative radio signal to said transmitter; and an electrically operable actuator associated with said receiver/controller circuit and with an object device to be operated, and responsive to said control signal to operate said object device to perform a desired operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A keyless entry system for operating an automotive vehicle devices, comprising:
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a manual switch mounted on an external surface of the vehicle body and accessible from outside the vehicle a pocket-portable transmitter, to be carried by a user of the vehicle, for transmitting a radio signal indicative of an unique code which identifies the transmitter in response to a demand in the form of a radio signal; a receiver/controller means, mounted on the vehicle and electrically connected to said manual switch, for transmitting a demand-indicative radio signal to said transmitter in response to manual operation of said manual switch, receiving said unique code-indicative radio signal from said transmitter, comparing said unique code of the received signal with a preset code, and producing a control signal when said unique code matches said preset code, said receiver/controller means including an antenna device for receiving said unique code-indicative radio signal by electromagnetic induction and having a first segment susceptible to electromagnetic induction and a second segment having substantially lower impedance than said first segment and inductively coupled with said first segment for generating a magnetic field of sufficient intensity to cause electromagnetic induction, thereby transmitting said demand-indicative radio signal to said transmitter; and an electrically operable actuator associated with said receiver/controller circuit and with said vehicle device to be operated, and responsive to said control signal to operate said vehicle device to perform a desired operation. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification