Transponder startup control method and interrogator for tire pressure monitoring system

• US 20050156723A1
• Filed: 12/29/2004
• Published: 07/21/2005
• Est. Priority Date: 01/20/2004
• Status: Active Grant

• Current Assignee: Omron Automotive Electronics Company Limited (Nidec Corporation)
• Original Assignee: Omron Corporation
• Inventors: Fujii, Masaki
• Granted Patent: US 7,336,163 B2
• Time in Patent Office: Days
• US Class Current: 340/447
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: B60C 23/0442 the transmitted signal comprises further information, e.g. instruction codes, sensor characteristics or identification data
• CPC Class Codes: B60C 23/0462 Structure of transmission protocol
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10079 the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions
• CPC Class Codes: G06K 7/10217 parameter settings controlling the transmission power of the interrogator
• CPC Class Codes: Y02A 40/60 Ecological corridors or buffer zones

Abstract

A passive transponder is started up by receiving an interrogation signal and returning a requested response signal. The startup is controlled by an interrogator using a startup control method by judging presence or absence of a return of the response signal while monotonically increasing transmission power of the interrogation signal from an initial value by an amount which is made smaller stepwise every time presence of the return is judged and maintaining the transmission power, after presence of the return is judged, at its value as of the time when presence of the return was judged.

Claims

1. A startup control method for a passive transponder adapted to be started up by receiving an interrogation signal and to return a requested response signal, said startup control method comprising the steps of:

judging presence or absence of a return of said response signal while monotonically increasing transmission power of said interrogation signal from an initial value by an amount which is made smaller stepwise every time presence of said return is judged; and

maintaining said transmission power, after presence of said return is judged, at the value of said transmission power as of the time when presence of said return was judged.

2. The startup control method of claim 1 further comprising the step of monotonically reducing said transmission power of said interrogation signal while presence or absence of said return of said response signal is being judged by an amount which is made smaller stepwise every time presence of said return is judged

3. The startup control method of claim 1 wherein said initial value is a variable, said startup control method further comprising the step of updating said initial value with the value of the transmission power at the time when presence of said return is judged.

4. The startup control method of claim 1 wherein presence or absence of said return is judged based on reception level of said response signal.

5. The startup control method of claim 1 wherein presence or absence of said return is judged based on whether or not correction of error in said response signal was carried out normally.

6. An interrogator for a tire pressure monitoring system that is used in pair with a passive transponder adapted to be started up by receiving an interrogation signal and to return a response signal that is requested and at least includes tire pressure data, said interrogator comprising:

a judging part that judges presence or absence of a return of said response signal while monotonically increasing transmission power of said interrogation signal from an initial value by an amount which is made smaller stepwise every time presence of said return is judged; and

a maintaining part that maintains said transmission power, after presence of said return is judged, at the value of said transmission power as of the time when presence of said return was judged by said judging part;

7. The interrogator of claim 6 further comprising a power reducing part that monotonically reduces the transmission power of said interrogation signal while presence or absence of said return of said response signal is being judged by an amount which is made smaller stepwise every time presence of said return is judged.

8. The interrogator of claim 6 wherein said initial value is a variable, said interrogator updating said initial value with the value of the transmission power at the time when presence of said return is judged.

9. The interrogator of claim 6 wherein presence or absence of said return is judged based on reception level of said response signal.

10. The interrogator of claim 6 wherein presence or absence of said return is judged based on whether or not correction of error in said response signal was carried out normally.

11. The interrogator of claim 6 wherein said initial value is set individually for each of tire positions.