Vehicular antitheft apparatus using an identification code transmitted from a key to allow engine starting
First Claim
1. A vehicular antitheft apparatus comprising:
- an ignition key cylinder having a key rotor into which a key is to be inserted;
an ignition switch for producing a turn detection signal when detecting that the key rotor has been turned to a predetermined position;
means for outputting a high-frequency signal when receiving the turn detection signal;
the key including;
a secondary battery;
means for generating a constant DC voltage based on the high-frequency signal;
a charging circuit for charging the secondary battery with the generated constant DC voltage;
a transmission circuit powered by the secondary battery, for transmitting an air propagation signal including an identification code; and
a timer circuit for allowing the transmission circuit to transmit the air propagation signal during a predetermined period after the generating means receives the high-frequency signal; and
means for comparing the identification code included in the air propagation signal transmitted from the key and a preset identification code, and for producing a signal for allowing an engine to be started if the transmitted identification code and the preset identification code are identical.
1 Assignment
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Accused Products
Abstract
When an ignition switch detects that a key rotor of an ignition key cylinder has been turned to the accessory position by a key, a controller energizes a primary coil to cause it to output a high-frequency signal. In the key, a secondary battery is charged with a constant DC voltage generated from an AC voltage induced across a secondary coil. A transmission circuit is powered by the secondary battery, and allowed by a timer circuit to transmit a radio signal including an identification code during a predetermined period after the high-frequency signal is received by the key. Alternatively, the controller energizes the primary coil plural times with a cycle consisting of predetermined output and pause periods if the transmitted identification code does not coincide with a preset identification code at the first comparing attempt.
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Citations
6 Claims
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1. A vehicular antitheft apparatus comprising:
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an ignition key cylinder having a key rotor into which a key is to be inserted; an ignition switch for producing a turn detection signal when detecting that the key rotor has been turned to a predetermined position; means for outputting a high-frequency signal when receiving the turn detection signal; the key including; a secondary battery; means for generating a constant DC voltage based on the high-frequency signal; a charging circuit for charging the secondary battery with the generated constant DC voltage; a transmission circuit powered by the secondary battery, for transmitting an air propagation signal including an identification code; and a timer circuit for allowing the transmission circuit to transmit the air propagation signal during a predetermined period after the generating means receives the high-frequency signal; and means for comparing the identification code included in the air propagation signal transmitted from the key and a preset identification code, and for producing a signal for allowing an engine to be started if the transmitted identification code and the preset identification code are identical. - View Dependent Claims (2, 3)
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4. A key comprising:
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a secondary battery; means for receiving a high-frequency signal; means for generating a constant DC voltage based on the high-frequency signal; a charging circuit for charging the secondary battery with the generated constant DC voltage; a transmission circuit powered by the secondary battery, for transmitting an air propagation signal including an identification code; and a timer circuit for allowing the transmission circuit to transmit the air propagation signal during a predetermined period after the generating means receives the high-frequency signal.
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5. A vehicular antitheft apparatus comprising:
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an ignition key cylinder having a key rotor into which a key is to be inserted; an ignition switch for producing a turn detection signal when detecting that the key rotor has been turned to a predetermined position; means for outputting a high-frequency signal when receiving the turn detection signal; the key including a transmission circuit for transmitting an air propagation signal including an identification code in response to the high-frequency signal; and control means for comparing the identification code included in the air propagation signal transmitted from the key and a preset identification code, for producing a signal for allowing an engine to be started if the transmitted identification code and the preset identification code are identical, and for causing the outputting means to output the high-frequency signal at plural times with a cycle consisting of predetermined output and pause periods if the transmitted identification code does not coincide with the preset identification code in a first attempt. - View Dependent Claims (6)
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Specification