1. Field of the Invention
The present invention in general relates to a detecting technique and more particular to a wheel position detecting device that detects a wheel position on a vehicle, the wheel position detecting device is preferably applied to a tire air pressure detecting device that detects tire air pressure.
2. Description of the Related Art
Conventionally, a direct-type tire air pressure detecting device is known as a tire air pressure detecting device. In the direct-type tire air pressure detecting device, a transmitter including a sensor, such as a pressure sensor, is directly mounted on a wheel side of a vehicle. A tire is attached to the wheel. An antenna and a receiver are provided on the vehicle-body side. The tire air pressure detecting device operates as follows. After the transmitter transmits a detection signal from the sensor, the receiver receives the detection signal, via the antenna, and the tire air pressure detecting device performs tire air pressure detection.
The tire air pressure detecting device adds identification (ID) information (identifier) to data transmitted from the transmitter so that whether the transmitting data is that of the vehicle on which the tire air pressure detecting device is mounted (own vehicle) and the wheel on which the transmitter is mounted can be determined. The ID information is used to determine whether the vehicle is the own vehicle or another vehicle. The ID information is also used to determine the wheel on which the transmitter is mounted. The ID information is registered to the receiver in advance. When the data transmitted from the transmitter is received, the tire air pressure detecting device determines the wheel to which the data belongs using the received ID information (refer to, for example, Japanese Patent Publication No. 3212311).
When a user himself changes the position of the wheel, such as through tire rotation, the tire air pressure detecting device cannot respond to the change in the wheel position unless the ID information of the wheels of which the tires have been rotated by the user is read and the read ID information is registered to the receiver over current ID information.