Tag Detecting System, Moving Object Detecting Method, and Entrance/Exit Management System

A tag detecting system comprising:

• a first generator emitting a pulse code modulated signal through a first antenna of a predetermined field strength;
• a second generator emitting a pulse code modulated signal through a second antenna of a predetermined field strength;
• a third generator emitting a pulse code modulated signal through a third antenna of a predetermined field strength;
• an RFID tag detecting the pulse code modulated signal at least from the first antenna, and transmitting a discrimination signal by responding to the pulse code modulated signal;
• and
• a receiver receiving the discrimination signal through a receiving antenna, wherein
• the first antenna and the second antenna are adjacently arranged to produce a first cross over area where high-frequency magnetic fields formed by both antennas are overlaid each other;
• the first antenna and the third antenna are adjacently arranged to produce a second cross over area where high-frequency magnetic fields formed by both antennas are overlaid each other;
• each of the first generator and the second generator emits the pulse code modulated signal at such a timing that spaces included in a predetermined part of the pulse code modulated signal emitted by any one of the first and second generators is occupied by the pulse code modulated signal emitted by the other of the first and second generators;
• each of the first generator and the third generator emits the pulse code modulated signal at such a timing that spaces included in a predetermined part of the pulse code modulated signal emitted by any one of the first and third generators is occupied by the pulse code modulated signal emitted by the other of the first and third generators;
• and
• a detection area in which the RFID tag is capable of detecting the pulse code modulated signal from the first antenna, is made to be restricted so that the RFID tag is made not to detect the pulse code modulated signals due to the spaces being occupied, if the RFID tag is located in the first cross over area or the second cross over area, or a part of the first cross over area or the second cross over area.

A moving object detecting method for detecting a movement of an object mounting an RFID tag comprised of:

• a step that a plurality of trigger antennas respectively form high-frequency magnetic fields in which there is a cross over area where parts of the magnetic fields are adjacently overlaid;
• a step that a plurality of generators emit pulse cord modulated signals corresponding to the respective high-frequency magnetic fields, and generate cross over trigger signals by overlaying the respective pulse code modulated signals in the cross over area;
• a step that an integrated circuit mounted on the RFID tag receives and transmits ID information corresponding to the pulse code modulated signal in the respective high-frequency magnetic fields;
• and
• a step that the integrated circuit receives and transmits ID information corresponding to the cross over trigger signal when the integrated circuit detects the cross over trigger signal in the cross over area.

An entrance/exit management system for monitoring a movement of a person having an RFID tag comprising:

• three trigger antennas which respectively form high-frequency magnetic fields having cross over areas in which adjacent magnetic fields are partially overlaid;
• the RFID tag which includes an integrated circuit;
• and
• the integrated circuit which detects respective pulse code modulated signals included in magnetic fields of the respective high-frequency magnetic fields, receives and transmits ID information corresponding to the respective pulse code modulated signals, and does not detect a cross over trigger signal in which the pulse code modulated signals included in the magnetic fields are overlaid, at least in a partial area of the cross over area;
• wherein
• the integrated circuit detects a direction of movement of the RFID tag based on a process that ID information changes corresponding to the respective pulse code modulated signals, and
• the integrated circuit discriminates the specific RFID tag in the high-frequency magnetic field located between the partial areas.