Mobile object identification system

• US 5,525,991 A
• Filed: 02/24/1994
• Issued: 06/11/1996
• Est. Priority Date: 06/25/1992
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Matsumoto, Manabu, Watanabe, Atsushi, Nagura, Michinaga, Kago, Yoshiyuki, Ando, Toshihide, Tokitsu, Naoki, Katoh, Taisei, Yamashita, Mutsushi
• Primary Examiner(s): Lobo, Ian J.
• Application Number:
  US08/204,179
• Time in Patent Office: 838 Days
• Field of Search: 340/636, 340/825.54, 340/928, 340/825.15, 340/825.32, 340/825.55, 342/42, 342/44, 342/69, 235/384, 250/341.1, 250/338.1
• US Class Current: 340/10.51
• CPC Class Codes: G01S 13/751 wherein the responder or reflector radiates a coded signal
• CPC Class Codes: G01S 13/765 with exchange of information between interrogator and responder
• CPC Class Codes: G01S 13/767 Responders; Transponders teaching or practice apparatus for gun-aiming or gun-laying using reflecting targets or active targets F41G3/26
• CPC Class Codes: G06K 1/128 by electric registration, e.g. electrolytic, spark erosion recording apparatus for measuring instruments G01D15/06; information storage in general G11
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 7/10059 transponder driven
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles
• CPC Class Codes: G06Q 20/341 Active cards, i.e. cards including their own processing means, e.g. including an IC or chip
• CPC Class Codes: G07B 15/063 using wireless information transmission between the vehicle and a fixed station identification of vehicles G08G
• CPC Class Codes: G07F 7/082 Features insuring the integrity of the data on or in the card
• CPC Class Codes: G07F 7/1008 Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system
• CPC Class Codes: G08G 1/017 identifying vehicles G08G1/015, G08G1/054 take precedence

Abstract

The primary object of the invention is to realize a mobile object identification system of simple construction and low cost, in which the responding unit attached to a mobile object writes data only once when it receives write signals repeatedly in communication with antenna units. When a tag unit (responding unit) receives a write signal from a writing antenna unit, it writes data to the data memory when a completion flag is cleared. When the data is first written, a control circuit sets the completion flag. Then, if the tag unit receives additional write signals in the communication area of the same writing antenna unit, the control circuit invalidates the data write command on the ground that the completion flag is set, thereby preventing duplicate data writing.

Claims

1. A responder which is attached to a movable object for writing data when receiving a write signal in a communication area of a writing interrogator and reading and transmitting data when receiving a read signal in said communication area of a reading interrogator, as said responder is moved with said movable object, said responder comprising:

data storage means for storing data;

control means for controlling a process of writing data into said storage means, and for controlling a process of reading data from said data storage means; and

status storage means for storing write completion status data when said control means controls said process of writing data to said data storage means in response to a first write signal from said writing interrogator;

said control means invalidating said process of writing data to said data storage means when said control means receives a second write signal from said writing interrogator.

6. A responder according to claim 1, wherein said control means invalidates said process of writing data to said data storage means when said control means receives a second write signal from said writing interrogator and said write completion status data retained in said status storage means indicates that said control means allowed data in response to said first write signal to be written to said data storage means.

2. A communication system for a mobile object identification system, comprising:

a responder transmitting and receiving signals through a mobile antenna mounted on a mobile object;

an interrogator transmitting and receiving signals through a plurality of stationary antennas installed along a moving area of said mobile object, said plurality of stationary antennas having respective communication areas which overlap partly in a direction of movement of said mobile object; and

a control device controlling an operation of said interrogator;

wherein said interrogator includes level judging and signal selecting means for simultaneously judging respective signal levels of a plurality of responding signals received respectively by said plurality of stationary antennas, for selecting one of said plurality of responding signals, and for outputting said selected one of said plurality of responding signals.

3. A mobile object identification system, comprising:

a responder mounted on a mobile object and which, when receiving an interrogatory signal with a first frequency, modulates by a responding signal an unmodulated carrier wave received after said interrogatory signal, and which transmits said responding-signal-modulated carrier wave;

a plurality of interrogators, each of said plurality of interrogators modulating a respective carrier wave having a predetermined frequency allocated for respective overlapping communication areas of each of said plurality of interrogators by a respective interrogatory signal, each of said plurality of interrogators transmitting said modulated carrier wave, followed by an unmodulated carrier wave, to said respective communication area, adjacent ones of said respective communication areas of said plurality of interrogators having different carrier frequencies, and each of said plurality of interrogators receiving a responding signal from said responder when positioned in said respective communication area; and

control means for controlling said plurality of interrogators so that said adjacent ones of said plurality of interrogators transmit said respective interrogatory signals at different times.

4. An electronic label for a mobile object identification system, comprising:

a responding circuit for storing vehicle information varying from vehicle to vehicle, said responding circuit outputting said vehicle information in response to an interrogatory signal received from an interrogator; and

a visual information sheet attached on a windshield glass of a vehicle to face said responding circuit, said visual information sheet being displayed on said vehicle so as to be seen from an exterior of said vehicle;

wherein at least said responding circuit is embedded in said windshield glass of said vehicle.

5. An electronic label for a mobile object identification system, comprising:

a responding circuit which is embedded in a windshield glass of a vehicle, said responding circuit storing vehicle information varying from vehicle to vehicle, and said responding circuit outputting said vehicle information in response to an interrogatory signal received from an interrogator;

said responding circuit being placed just above a rear view mirror of said vehicle and connected to a battery of said vehicle through a power line.