Door entry control by wireless communication

• US 6,218,929 B1
• Filed: 06/10/1998
• Issued: 04/17/2001
• Est. Priority Date: 06/12/1997
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation, Nippon Soken, Inc.
• Original Assignee: DENSO Corporation, Nippon Soken, Inc.
• Inventors: Uesaka, Hiroto, Kato, Yuji, Ohtsuka, Mitsugi, Asakura, Fumio, Furuta, Noritoshi
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): Bangachon, William L.
• Application Number:
  US09/095,155
• Time in Patent Office: 1,042 Days
• Field of Search: 340/825.69, 340/825.31, 340/825.72, 340/825.54, 340/10--, 340/10-1-, 340/825.39, 340/5.1, 340/5.2, 340/5.3
• US Class Current: 340/5.2
• CPC Class Codes: G07C 2009/00357 and the lock having more than one limited data transmission ranges
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks

Abstract

In a vehicular entry control system, a code signal transmitter of a card carried by a driver modulates by a card-specific code a signal received from a transmitter/receiver of a control unit mounted in a vehicle and transmits the modulated signal to the control unit in return. The transmitter/receiver demodulates the modulated signal and a microcomputer automatically unlocks a vehicle door when the demodulated signal is correct indicating that the card is carried into a demodulating area. The microcomputer locks the door upon a driver'"'"'s manual operation on a locking switch of the card. The microcomputer prohibits the automatic unlocking as long as the card is within the demodulating area after the locking in response to the manual operation.

Claims

1. A passenger entry control system for a vehicle comprising:

code signal transmitting means for modulating a fixed frequency signal transmitted from the vehicle using a code assigned specifically to the vehicle and transmitting the modulated code signal;

transmitting/receiving means mounted in the vehicle for transmitting the fixed frequency signal and receiving the code signal;

switching control means mounted in the vehicle for switching automatically a door of the vehicle from a locked condition to an unlocked condition when the code signal from the code signal transmitting means is received and demodulated; and

manual locking means for causing the switching control means to switch the door to the locked condition from the unlocked condition upon manual operation of the code signal transmitting means, wherein

the switching control means is set to disable the automatic unlocking of the door after the manual locking means causes the switch control means to switch the door to the locked condition and while the code signal from the code signal transmitter means continues to be received and demodulated correctly by the transmitting/receiving means, the switch control means ceasing disablement of the automatic unlocking when the switch control means detects that the code signal transmitting means is moved outside a code signal demodulating area by detecting that the code signal transmitter no longer continues to correctly receive and demodulate the code signal.

2. The control system as in claim 1, wherein:

the manual locking means includes a locking signal transmitting means provided integrally with the code signal transmitting means for transmitting a locking signal modulated by the manual operation on the manual locking means, and locking signal receiving means mounted in the vehicle for receiving the modulated locking signal from the locking signal transmitting means; and

the switching control means is set to change from the door unlocking condition to the door locking condition in response to a demodulation of the modulated locking signal by the locking signal receiving means.

3. The control system as in claim 1, further comprising:

transmission control means mounted in the vehicle for controlling the transmitting/receiving means to transmit the fixed frequency signal when the door is locked and to stop transmitting the fixed frequency signal when the door is unlocked.

4. The control system as in claim 1, further comprising:

door opening/closing detecting means for detecting an opening and closing of the door, wherein

the switching control means is set to lock the door when the door is kept closed for a time period after the door is unlocked.

5. The system of claim 1, wherein the switching control means is set to maintain the locking condition of the door after the manual locking means causes the switch control means to switch the door to the locked condition and while the code signal from the code signal transmitter means continues to be received and demodulated correctly by the transmitting/receiving means.

6. The system of claim 1, wherein the code signal transmitting means further includes:

a first receiving antenna arranged to receive the fixed frequency signal from the transmitting/receiving means;

a modulator circuit for modulating the signal received by the receiving antenna; and

a first transmitting antenna arranged to transmit the modulated signal from the modulator circuit as the code signal.

7. The system of claim 6, wherein the transmitting/receiving means further includes:

a second receiving antenna arranged to receive the code signal from the first transmitting antenna; and

a second transmitting antenna arranged to transmit the fixed frequency signal to the first receiving antenna.

8. The system of claim 7, wherein the first receiving antenna and the second transmitting antenna have a carrier frequency of approximately 2.45 GHz and the first transmitting antenna and the second receiving antenna have a transmission frequency of approximately 400 MHz.

9. A method of controlling entry of a user through a door by wireless communication between a portable unit and a control unit connected with the door, the method comprising the steps of:

unlocking the door automatically when the portable unit is moved from outside of a predetermined communication area from the control unit to inside the predetermined communication area;

locking the door in response to a door locking instruction signal transmitted from the portable unit upon a manual operation on the portable unit; and

disabling the automatic unlocking of the door when the door is locked in response to the door locking instruction signal and when the portable unit is inside of the predetermined communication area, and ceasing the disablement of the automatic unlocking based on a detection of the portable unit leaving the predetermined communication area.

10. The method as in claim 9, wherein both unlocking the door automatically and disabling the automatic unlocking include:

transmitting a signal from the control unit to the portable unit;

modulating the signal at the portable unit in accordance with a code assigned to the portable unit;

transmitting the modulated signal from the portable unit to the control unit;

demodulating the modulated signal at the control unit; and

determining whether the portable unit is inside the predetermined communication area from the demodulated code.

11. The method as in claim 10, wherein:

the modulated signal is transmitted to the portable unit intermittently.