Patent ID: 7864027

Claim:
A system including electronic tags and a communication apparatus that communicates with the electronic tags, wherein each of the electronic tags includes a display unit and a storage unit containing an ID including a first part and a second part, the first part of the ID representing one of group IDs identifying groups among the electronic tags, the second part of the ID indicating a response timing, and is configured to send a response when a group request sent from the communication apparatus contains the one of the group IDs represented by the first part of the ID; wherein the communication apparatus includes a management database containing electronic tag information for managing the electronic tags and display information associated with the electronic tag information and to be displayed on the display units of the electronic tags, and is configured to obtain upon power-on the group IDs assigned to the communication apparatus and to send group requests one by one each of which group requests contains one of the obtained group IDs, thereby to request the electronic tags group by group to send responses to the communication apparatus for all groups, and to recreate the management database based on the responses by registering in the management database the obtained electronic tag information contained in the responses; and wherein each of the electronic tags in each one of the groups is configured to send the response at the response timing indicated by the second part of the ID so as not to cause a collision between the responses.