Tire Pressure Measuring System and Tire Pressure Measuring Device

• US 20090184815A1
• Filed: 01/24/2007
• Published: 07/23/2009
• Est. Priority Date: 01/30/2006
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Hasegawa, Kazuo, Akama, Eiji, Suzuki, Hirohisa
• Granted Patent: US 8,330,594 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 23/0413 Wireless charging of active radio frequency circuits
• CPC Class Codes: B60C 23/0433 Radio signals
• CPC Class Codes: B60C 23/0462 Structure of transmission protocol

Abstract

A tire pressure measuring system (TPMS) for transmitting pressure information from a tire to a vehicle body has a complicated structure when a plurality kinds of transmission data exist. A sensor unit receives a transmission electromagnetic field from a sensor control unit, and rectify-detects the received field. The counter of the sensor unit determines a rotation cycle of a tire, based on the signal obtained by the rectification detection, then switches the switch in conjunction with the rotation cycle, and sequentially sends the plurality of transmission data items for every tire rotation.

Claims

1. A tire pressure measuring system in which a control unit mounted on a vehicle body is connected by radio to a sensor unit mounted on a tire of the vehicle body, for transmitting air pressure inside the tire, measured by the sensor unit, to the control unit, wherein

the control unit comprises

an electromagnetic field generation circuit for generating a transmission electromagnetic field varying at a predetermined transmission frequency, and

a data receiving circuit for detecting transmission data from the sensor unit, based on variation of the transmission electromagnetic field, the variation caused due to the sensor unit,

the sensor unit comprises

an antenna for receiving the transmission electromagnetic field, and through interaction with the transmission electromagnetic field, affecting the transmission electromagnetic field such that the transmission electromagnetic field varies, to thereby communicate with the control unit, and

a data transmission circuit for changing an antenna current flowing in the antenna to thereby cause the transmission electromagnetic field to vary, and alternately transmitting a plurality kinds of transmission data, including the air pressure, and

the data transmission circuit detects a rotation cycle of the tire, based on change of strength with which the transmission electromagnetic field is received, and carries out a transmission operation while switching the kinds of transmission data in conjunction with the rotation cycle.

2. The tire pressure measuring system according to claim 1, wherein

the data transmission circuit includes

a detector circuit for rectifying-detecting the variation of the transmission electromagnetic field in accordance with the transmission frequency, and

a rotation detection circuit for detecting one rotation of the tire, based on change of an output level of the detector circuit between when the sensor unit carries out communication with the control unit and when the sensor unit does not.

3. The tire pressure measuring system according to claim 1, wherein

the data transmission circuit includes

a storage unit for storing information specifying the kind of transmission data to be next transmitted, and

a power supply unit for storing power obtained from the transmission electromagnetic field, and supplying operating power to the storage unit continuously over a plurality of the rotation cycles to thereby enable storage of the information.

4. The tire pressure measuring system according to claim 1, wherein

the sensor unit comprises a temperature sensor for measuring temperature inside the tire, and

the transmission data includes the temperature, in addition to the air pressure.

9. The tire pressure measuring system according to claim 2, wherein

the data transmission circuit includes

a storage unit for storing information specifying the kind of transmission data to be next transmitted, and

a power supply unit for storing power obtained from the transmission electromagnetic field, and supplying operating power to the storage unit continuously over a plurality of the rotation cycles to thereby enable storage of the information.

10. The tire pressure measuring system according to claim 2, wherein

the sensor unit comprises a temperature sensor for measuring temperature inside the tire, and

5. A tire pressure measuring device, comprising:

an antenna for interaction with a supply electromagnetic field given from outside to thereby cause the supply electromagnetic field to change in amplitude, and

a data transmission circuit for changing an antenna current flowing in the antenna to thereby change the amplitude of the supply electromagnetic field, and alternately transmitting to the outside a plurality kinds of transmission data including air pressure,

wherein

the data transmission circuit detects a rotation cycle of a tire, based on change of strength with which to receive the supply electromagnetic field, and carries out a transmission operation while switching the kinds of transmission data in conjunction with the rotation cycle.

6. The tire pressure measuring device according to claim 5, wherein

the data transmission circuit includes

a detector circuit for rectifying-detecting variation of the supply electromagnetic field in accordance with frequency of the supply electromagnetic field,

a rotation detection circuit for detecting one rotation of the tire, based on change of an output level of the detector circuit.

7. The tire pressure measuring device according to claim 5, wherein

the data transmission circuit includes

a storage unit for storing information specifying the kind of transmission data to be next transmitted, and

a power supply unit for storing power obtained from the supply electromagnetic field, and supplying operating power to the storage unit continuously over a plurality of the rotation cycles to thereby enable storage of the information.

8. The tire pressure measuring device according to claim 5, further comprising:

a temperature sensor for measuring temperature inside the tire,

wherein

the transmission data includes the temperature, in addition to the air pressure.

11. The tire pressure measuring device according to claim 6, wherein

the data transmission circuit includes

a storage unit for storing information specifying the kind of transmission data to be next transmitted, and

a power supply unit for storing power obtained from the supply electromagnetic field, and supplying operating power to the storage unit continuously over a plurality of the rotation cycles to thereby enable storage of the information.

12. The tire pressure measuring device according to claim 6, further comprising:

a temperature sensor for measuring temperature inside the tire,

wherein

the transmission data includes the temperature, in addition to the air pressure.