Abstract: 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.

Abstract: 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.

Abstract: An antenna device includes a ground plate, a patch portion disposed parallel to the ground plate with a particular spacing, a plurality of short circuit portions that electrically connect the patch portion to the ground plate, and a loop portion which is a loop shaped conductor member at a particular spacing from an outer edge portion of the patch portion. The patch portion has an area which forms an electrostatic capacitance that causes parallel resonance with an inductance provided by the short circuit portions at a particular target frequency. The loop portion is formed with a perimeter length which is an integral multiple of the wavelength of radio waves at the target frequency. A feed point is disposed on the loop portion, and current is supplied to the patch portion through the loop portion.

Abstract: An antenna device includes a ground plate, a patch portion disposed parallel to the ground plate with a particular spacing, a plurality of short circuit portions that electrically connect the patch portion to the ground plate, and a loop portion which is a loop shaped conductor member at a particular spacing from an outer edge portion of the patch portion. The patch portion has an area which forms an electrostatic capacitance that causes parallel resonance with an inductance provided by the short circuit portions at a particular target frequency. The loop portion is formed with a perimeter length which is an integral multiple of the wavelength of radio waves at the target frequency. A feed point is disposed on the loop portion, and current is supplied to the patch portion through the loop portion.

Abstract: 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.

Abstract: 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 ?[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 ?[i] stored in the memory are calculated as a phase difference ??[i] and a time difference ?t[i]. A phase addition value ?sum[i] obtained by cumulatively adding a plurality of the phase differences ??[i] is calculated so as to correct a phase difference in which the corresponding time difference ?t[i] among the calculated plurality of the phase differences ??[i] exceeds a time threshold tsa [i], whereby the movement state of the radio tag is detected based upon the calculated phase addition value ?sum[i].

Abstract: A wireless tag passing determination apparatus includes: an antenna that provides multiple communicable regions and a communication disabled region, the communicable regions being arranged alternately with the communication disabled region, such that the communicable regions includes both sides of a passing determination point in a longitudinal direction of a passage in which passing of a wireless tag is determined; a tag reader that determines whether to read a signal transmitted by the wireless tag, based on a signal representing electric wave transmitted by the wireless tag existing in the communicable regions and received by the antenna; and a passing determination section that determines whether the wireless tag passes by the passing determination point, based on a pattern of presence or absence of reading in association with a lapse of time.

Abstract: 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.

Abstract: A tag reader includes: a phase calculation section that sequentially calculates a phase of a reception wave; a phase difference calculation section that calculates a phase difference as a difference of phases calculated at two time points; and a tag angle calculation section that calculates a tag angle between a straight line connecting an antenna and the wireless tag and a line on which the wireless tag is moving. The phase difference calculation section calculates two values of the phase difference. The tag angle calculation section calculates a first tag angle and a second tag angle. The tag reader comprises a tag distance calculation section that calculates an antenna-tag minimum distance as a minimum distance from the line to the antenna.

Abstract: 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 ?[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 ?[i] stored in the memory are calculated as a phase difference ??[i] and a time difference ?t[i]. A phase addition value ?sum[i] obtained by cumulatively adding a plurality of the phase differences ??[i] is calculated so as to correct a phase difference in which the corresponding time difference ?t[i] among the calculated plurality of the phase differences ??[i] exceeds a time threshold tsa [i], whereby the movement state of the radio tag is detected based upon the calculated phase addition value ?sum[i].

Abstract: A wireless tag passing determination apparatus includes: an antenna that provides multiple communicable regions and a communication disabled region, the communicable regions being arranged alternately with the communication disabled region, such that the communicable regions includes both sides of a passing determination point in a longitudinal direction of a passage in which passing of a wireless tag is determined; a tag reader that determines whether to read a signal transmitted by the wireless tag, based on a signal representing electric wave transmitted by the wireless tag existing in the communicable regions and received by the antenna; and a passing determination section that determines whether the wireless tag passes by the passing determination point, based on a pattern of presence or absence of reading in association with a lapse of time.

Abstract: A tag reader includes: a phase calculation section that sequentially calculates a phase of a reception wave; a phase difference calculation section that calculates a phase difference as a difference of phases calculated at two time points; and a tag angle calculation section that calculates a tag angle between a straight line connecting an antenna and the wireless tag and a line on which the wireless tag is moving. The phase difference calculation section calculates two values of the phase difference. The tag angle calculation section calculates a first tag angle and a second tag angle. The tag reader comprises a tag distance calculation section that calculates an antenna-tag minimum distance as a minimum distance from the line to the antenna.