Wireless door locking and unlocking system for motor vehicles having theft alarm device

• US 5,420,568 A
• Filed: 03/30/1993
• Issued: 05/30/1995
• Est. Priority Date: 03/31/1992
• Status: Expired due to Fees

• Current Assignee: Kansei Company
• Original Assignee: Kansei Company
• Inventors: Hashimoto, Masato, Iida, Tatsumi
• Primary Examiner(s): Rogers, Scott A.
• Assistant Examiner(s): Stoll, Thomas L.
• Application Number:
  US08/040,262
• Time in Patent Office: 791 Days
• Field of Search: 340/542, 340/825.69, 340/825.72, 341/176, 455/38.2, 455/254, 70/180, 70/256, 70/263, 180/167, 180/287
• US Class Current: 340/542
• CPC Class Codes: B60R 25/1004 Alarm systems characterised by the type of sensor, e.g. current sensing means using door lock sensors B60R25/1001
• CPC Class Codes: G06K 19/0707 the arrangement being capable of collecting energy from external energy sources, e.g. thermocouples, vibration, electromagnetic radiation G06K19/0702 takes precedence
• CPC Class Codes: G06K 19/0712 the arrangement being capable of triggering distinct operating modes or functions dependent on the strength of an energy or interrogation field in the proximity of the record carrier active means for hindering electromagnetic reading or writing G06K19/07336
• CPC Class Codes: G07C 2009/00198 the keyless data carrier having more than one limited data transmission ranges
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 2209/63 Comprising locating means for detecting the position of the data carrier, i.e. within the vehicle or within a certain distance from the vehicle
• CPC Class Codes: G07C 9/00182 operated with unidirectional data transmission between data carrier and locks
• CPC Class Codes: Y10T 70/5973 Remote control

Abstract

A wireless door locking and unlocking system for locking and unlocking the door of a motor vehicle having a theft alarm device. Further, the wireless door locking and unlocking system may be available for a door or a window of a house or the like. The car theft alarm device detects a car theft positively to produce an alarm signal. In the wireless door locking and unlocking system, the door-unlocking-signal receiving range is adjusted so that the occurrence of theft is positively prevented.

Claims

1. A wireless door locking and unlocking system with a control circuit which receives a door locking signal and a door unlocking signal from a transmitter, to lock and unlock a door, an improvement characterized in that the door is allowed to be unlocked in response to the door unlocking signal only when said transmitter is within a first predetermined receiving range from the door and the door is locked in response to the door locking signal when said transmitter is within a second predetermined receiving range, wherein said first receiving range is less than said second receiving range.

2. A wireless door locking and unlocking system with a control circuit which receives a door locking signal and a door unlocking signal from a transmitter, to lock and unlock a door, said system comprising:

field strength detecting means for determining, when a door unlocking signal is received from said transmitter, whether or not the magnitude of said door unlocking signal is at least a predetermined value;

said control circuit operating to unlock said door when said field strength detecting means has determined that the magnitude of said door unlocking signal is equal to or higher than the predetermined value, and operating to lock said door in response to said door locking signal irrespective of the magnitude of said door locking signal.

3. The wireless door locking and unlocking system as defined in claim 2 further comprising means for adjusting the predetermined value.

4. A wireless door locking and unlocking system with a control circuit which receives a door locking signal and a door unlocking signal from a transmitter, to lock and unlock a door, an improvement characterized in that the door is allowed to be unlocked in response to the door unlocking signal only when said transmitter is within a predetermined area from the door, said system comprising:

a receiver which receives either said door locking signal or said door unlocking signal from said transmitter, and wherein said receiver comprises;

state detecting means for detecting whether said door has been locked or unlocked; and

signal-receiving-sensitivity attenuating means for lowering, when said state detecting means detects that said door has been locked, the signal receiving sensitivity of said receiver.

5. The wireless door locking and unlocking system as defined in claim 4 wherein said signal-receiving-sensitivity attenuating means lowers the signal receiving sensitivity of said receiver by way of partially grounding the radio wave applied through an antenna to an RF amplifier of said receiver.

6. The wireless door locking and unlocking system as defined in claim 4 wherein said signal-receiving-sensitivity attenuating means lowers the signal receiving sensitivity by way of controlling the input of an intermediate frequency amplifier of said receiver.

7. The wireless door locking and unlocking system as defined in claim 4 wherein said signal-receiving-sensitivity attenuating means lowers the signal receiving sensitivity by way of controlling the gain of an intermediate frequency amplifier of said receiver.