Abstract: A control unit of a tire-mounted sensor determines whether a tire has been exchanged. When the tire has been exchanged, the control unit changes the threshold value of a road surface state determination condition used for detecting the road surface state from vibration data of the tire detected by an acceleration sensor of the tire-mounted sensor. For example, the threshold value of the road surface state determination condition is reset upon determining that the tire has been exchanged, by transmitting an instruction to the tire-mounted sensor through a tool at an automobile maintenance shop, etc.

Abstract: A condition in which an abnormality can occur in a tire is accurately detected on the basis of a detection signal from an acceleration sensor used to detect a road surface state and a possibility that an abnormality has occurred in the tire is also detected. In addition, the detection result is stored as a diagnosis history. The diagnosis history or the possibility that an abnormality has occurred in the tire are notified through a notification device in a vehicle body side system so that a user is informed in advance of the possibility that an abnormality has occurred in the tire. In addition, when the diagnosis history is checked through a tool in a car repair shop, etc., the diagnosis history stored in a tire-mounted sensor is read out. Accordingly, the possibility of abnormality of the tire can be informed also in the car repair shop, etc.

Abstract: A tire-mounted sensor is mounted to a rear surface of a tread of a tire. the tire-mounted sensor includes: a vibration detector, a signal processor, a transmitter, and an activation controller. The vibration detector outputs a detection signal according to amplitude of a vibration of the tire. The signal processor extracts a ground contact section during which the portion of the tread provided with the vibration sensor is in contact with the ground, from the detection signal, and generates a road surface data based on the detection signal during the ground contact section. The transmitter transmits the road surface data. The activation controller starts an activation of the signal processor at a time in association with the ground contact starting time at which the portion of the tread provided with the vibration detector begins to be in contact with the ground.

Abstract: A tire-mounted sensor includes a vibration detector, an acceleration sensor, a signal processor, and a transmitter. The vibration detector outputs a detection signal according to amplitude of a vibration of the tire. The acceleration outputs a detection signal according to an acceleration of the tire in a radial direction. The signal processor detects a rotational angle of the tire reaching a ground angle during each rotation of the tire, sets a measurement period including a time period during which the rotational angle of the tire is at the ground angle, extracts a ground contact section during which the portion of the tread provided with the vibration sensor is in contact with the ground, in the measurement period, and generates a road surface data based on the detection signal output from the vibration detector during the ground contact section. The transmitter transmits the road surface data.