Transmit-receive system

• US 5,777,570 A
• Filed: 03/28/1996
• Issued: 07/07/1998
• Est. Priority Date: 03/31/1995
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Tokai RIKA Denki Seisakusho
• Original Assignee: Kabushiki Kaisha Tokai RIKA Denki Seisakusho
• Inventors: Kokubu, Sadao
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): WONG, ALBERT KANG
• Application Number:
  US08/623,005
• Time in Patent Office: 831 Days
• Field of Search: 341/173, 341/174, 340/870.31, 340/870.37, 340/870.3, 340/870.07, 340/870.16, 340/825.04, 340/825.06, 340/825.2, 340/825.21, 340/825.3, 340/825.44 , 340/825.54, 340/825.69, 380/21, 380/23
• US Class Current: 341/173
• CPC Class Codes: G07C 2009/00388 code verification carried out according to the challenge/response method
• CPC Class Codes: G07C 2009/00777 by induction
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks

Abstract

A transmit-receive system is composed of a portable transmitter-receiver and an external transmitter-receiver that exchange data by using air-propagating signals. The portable unit has a start switch, and transmits a start signal to the external unit when the start switch is turned on. Upon receiving the start signal, the external unit transmits a question signal to the portable unit. Upon receiving the question signal, the portable unit transmits thereto a response signal. Optionally, the external unit intermittently transmits the question signal, and becomes ready to receive during the question signal intermission. The external unit stops transmission of the question signal if it transmits the question signal a predetermined number of times without receiving the response signal. Further, the external unit intermittently becomes ready to receive for periods shorter than the question signal intermission.

Claims

1. A transmit-receive system for data transmission and reception by using air-propagating signals comprising:

a portable transmitter-receiver having a start switch; and

an external transmitter-receiver,

wherein the portable transmitter-receiver transmits a start signal to the external transmitter-receiver when the start switch is turned on, and wherein upon receiving the start signal, the external transmitter-receiver transmits a question signal to the portable transmitter-receiver, and wherein upon receiving the question signal, the portable transmitter-receiver transmits a response signal to the external transmitter-receiver; and

wherein while waiting to receive the start signal, the external transmitter-receiver intermittently becomes ready to receive, and wherein a period during which the external transmitter-receiver is ready to receive while waiting to receive the start signal is shorter than the intermission of the question signal.

2. A transmit-receive system according to claim 1, wherein the system is applied to a vehicular electronic key system.

3. A transmit-receive system according to claim 1, wherein the external transmitter-receiver intermittently transmits the question signal and becomes ready to receive during an intermission of the question signal, and wherein the external transmitter-receiver stops transmission of the question signal if the external transmitter-receiver has transmitted the question signal a predetermined number of times without receiving the response signal.

4. A transmit-receive system according to claim 3, wherein the system is applied to a vehicular electronic key system.

5. A transmit-receive system for data transmission and reception comprising:

an external transmitter-receiver;

a portable transmitter-receiver having a start switch, wherein the portable transmitter-receiver transmits a start signal to the external transmitter-receiver when the start switch is turned on; and

means for transmitting, upon receiving the start signal, a signal from the external transmitter-receiver to the portable transmitter-receiver that repetitively alternates between a question signal period and a reception-ready period upon a single activation of said start switch.