Patent ID: 8174365

Claim:
A method of identifying tags in a communication area through an anti-collision by a reader/writer, the tags including first and second tags in the communication area, the first tag including a first memory storing a first tag ID and a first sleep flag, the second tag including a second memory storing a second tag ID and a second sleep flag, the first tag ID being different from the second tag ID, the method comprising: transmitting a first WAKE command from the reader/writer; setting, in response to the first WAKE command, a first value to the first sleep flag, the first value of the first sleep flag being indicative of a permission of a transmission of the first tag ID; setting, in response to the first WAKE command, a first value to the second sleep flag, the first value of the second sleep flag being indicative of a permission of a transmission of the second tag ID; transmitting a first tag ID read command from the reader/writer after the setting of the first value to the first sleep flag and of the first value to the second sleep flag in response to the first WAKE command; transmitting, in response to the first tag ID read command, the first tag ID from the first tag and the second tag ID from the second tag; detecting a collision of the received first and second tag IDs to transmit a tag ID read/SLEEP command from the reader/writer, the tag ID read/SLEEP command including a first tag ID range as a condition, the first tag ID range including the second tag ID but not including the first tag ID; receiving the tag ID read/SLEEP command at the first tag to transmit the first tag ID from the first tag; receiving the tag ID read/SLEEP command at the second tag to set a second value to the second sleep flag, the second value of the second sleep flag being indicative of a prohibition of the transmission of the second tag ID; and receiving, at the reader/writer, the first tag ID transmitted corresponding to the tag ID read/SLEEP command to identify the first tag in the communication area.