Denso Wave Corporation

Yusuke Masuda

Kohei Enomoto

Masayuki Ogawa

Eiji Muto

An interference suppression apparatus suppresses electromagnetic field interference produced by an RFID tag. The interference suppression apparatus includes a power supply circuit, an antenna that is connected to the power supply circuit, a clock that is connected to the power supply circuit, and a load adjuster that is connected to the power supply circuit. The clock generates an output in which a time constant is adjusted to be longer than a communication time of the RFID tag. The load adjuster changes a characteristic of the antenna based on the output from the clock.

Interference suppression apparatus and interference suppression system

A configuration which can easily discriminate a moving wireless (radio) tag from a stationary wireless (radio) tag. The configuration uses an antenna to measure phases of response waves received from a wireless tag. Based on the measurements, the configuration measures changes in distance from the wireless tag to the antenna and detects travel of the wireless tag. Based on the measurements, the configuration measures changes in velocity of the wireless tag relative to the antenna. A wireless tag having a rate of changes in signs of the velocity, of not less than a predetermined value in the measured velocity changes, is detected as being a stationary tag.

Apparatus for detecting tag movements and wireless tag reader

In a configuration for detection of a movement state of a radio tag using a phase difference of a response wave from the radio tag, a phase &#x3c6;[i] and a measurement time t[i] of a response wave from a radio tag measured are sequentially stored in a memory. A difference from a previous phase and a difference from a previous measurement time with respect to each phase &#x3c6;[i] stored in the memory are calculated as a phase difference &#x394;&#x3c6;[i] and a time difference &#x394;t[i]. A phase addition value &#x3c6;sum[i] obtained by cumulatively adding a plurality of the phase differences &#x394;&#x3c6;[i] is calculated so as to correct a phase difference in which the corresponding time difference &#x394;t[i] among the calculated plurality of the phase differences &#x394;&#x3c6;[i] exceeds a time threshold tsa [i], whereby the movement state of the radio tag is detected based upon the calculated phase addition value &#x3c6;sum[i].

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Chita-gun, Japan

Yusuke Masuda