Patent ID: 8547119

Claim:
A dynamic quantity detection device comprising: a detection portion configured to detect a dynamic quantity applied from an outside and generate a sensor signal in accordance with the dynamic quantity; a signal process portion configured to process the sensor signal from the detection portion to have a property suitable for an external device; a communication portion configured to transmit the sensor signal that is processed by the signal process portion to the external device; and an operation mode switch portion configured to switch an operation mode, wherein when the sensor signal output from the detection portion is less than or equal to a predetermined threshold value, the operation mode switch portion sets the operation mode to a power save mode by stopping an operation of the signal process portion, when the sensor signal output from the detection portion is greater than the predetermined threshold value, the operation mode switch portion switches the operation mode to a normal mode by activating the signal process portion, in the power save mode, the operation mode switch portion stops an operation of the communication portion, in the normal mode, the operation mode switch portion operates the communication portion, and the operation mode switch portion is configured to periodically switch the operation mode from the power save mode to the normal mode so that the sensor signal that is processed by the signal process portion is periodically transmitted from the communication portion.