Patent ID: 8633807
Filing Date: 2014-01-21
Classification: G06K

Abstract:
1. An RF tag reader and writer comprising: a communication unit that performs a communication process with an RF tag using a slot aloha method of performing the communication process with the RF tag as an information acquisition target at each of a plurality of time slots of a round, transmits a response request command to the RF tag at each time slot, acquires a response transmitted from the RF tag with an acquisition of the response request command, transmits a tag information request command for requesting for transmitting tag information, which is information stored in the RF tag, to the RF tag having transmitted the acquired response, and acquires the tag information transmitted from the RF tag with an acquisition of the tag information request command; and a communication success rate calculator that calculates a communication success rate a a signal level information acquiring section that acquires received signal level information which is information indicating the magnitude of a signal transmitted from the RF tag; a signal level determining section that acquires signal level reference information, which is a reference for the magnitude of the received signal, stored in a predetermined memory area, determines whether the magnitude of the received signal transmitted from the RF tag is greater than the reference on the basis of a comparison result of the signal level reference information with the received signal level information acquired by the signal level information acquiring section for every time slot, and determines that a response is transmitted from the RF tag with the acquisition of the response request command transmitted from the communication unit at the time slot at which the magnitude of the received signal is greater than the reference; a response rate calculator that calculates a response rate a a communication stability determining unit that performs a communication state determining process of determining whether a communication state with the RF tag is good on the basis of a comparison result of communication success rate reference information, which is a reference for the communication success rate and is acquired from a predetermined memory area, with the communication success rate a