Tire Inflation Pressure Determining System and Tire Inflation Pressure Determining Apparatus
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0 Petitions
Accused Products
Abstract
A tire inflation pressure determining system is provided in which measurement results are transmitted to the exterior without providing a high precision oscillation circuit to a tire-mounted air pressure determining system.
An LC resonance circuit is composed of a coil Ls and an inflation pressure sensor in which the electric capacitance varies in accordance with tire air pressure. The fluctuations of the electromagnetic field having a frequency f0 generated by a sensor control unit are sensed in a coil L2, a clock is generated based on the sensed fluctuations, the clock is inputted to a coil Le that is transformer coupled to the coil Ls, and the LC resonance circuit is excited. The output voltage of the LC resonance circuit is converted to digital data in an A/D conversion circuit in correspondence with the intensity of the resonance, the impedance of the coil L2 is varied in accordance with the bit sequence constituting the data, and a modulation is thereby generated in the voltage of a coil L1 of the sensor control unit via the electromagnetic field.
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Citations
38 Claims
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13. A tire inflation pressure determining apparatus, comprising:
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an antenna for converting variations in a supplied electromagnetic field applied from the exterior, and generating electromagnetic field fluctuations toward the exterior; an inflation pressure sensor whose electric capacitance varies in accordance with air pressure inside a tire; a sensor resonance circuit for producing electrical resonance in accordance with the electric capacitance; a data generation circuit for generating transmission data that includes information of the air pressure on the basis of intensity of the electrical resonance; and a response circuit for varying electric current that flows to the antenna in accordance with bit values of the transmission data represented by digital data, and generating the electromagnetic field fluctuations, wherein the transmission data is transmitted to the exterior with the aid of the electromagnetic field fluctuations. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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32. A tire inflation pressure determining apparatus, comprising:
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an antenna for converting variations in a supplied electromagnetic field applied from the exterior, and generating electromagnetic field fluctuations toward the exterior; a level-sensing circuit for sensing a strong connection state in which amplitude of an AC signal outputted from the antenna in accordance with the variations in the supplied electromagnetic field is at a predefined level or higher; an inflation pressure sensor for determining air pressure inside a tire; a data generation circuit for generating transmission data that includes information of the air pressure; and a response circuit for varying electric current that flows to the antenna in accordance with bit values of the transmission data represented by digital data, and generating the electromagnetic field fluctuations when the strong connection state has been sensed, wherein the transmission data is transmitted to the exterior with the aid of the electromagnetic field fluctuations. - View Dependent Claims (34, 35, 36, 37, 38)
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33. A tire inflation pressure determining apparatus, comprising:
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an antenna for converting variations in a supplied electromagnetic field applied from the exterior, and generating electromagnetic field fluctuations toward the exterior, a level-sensing circuit for sensing a strong connection state in which amplitude of an AC signal outputted from the antenna in accordance with the variations in the supplied electromagnetic field is at a predefined level or higher; an inflation pressure sensor for determining air pressure inside a tire; a data generation circuit for generating transmission data that includes information of the air pressure and information of the strong connection state; and a response circuit for varying electric current that flows to the antenna in accordance with bit values of the transmission data represented by digital data, and generating the electromagnetic field fluctuations when the strong connection state has been sensed; and
whereinthe transmission data is transmitted to the exterior with the aid of the electromagnetic field fluctuations, and the rotational speed of a tire can be measured by allowing information of the strong connection state to be periodically received at the exterior.
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Specification