US 2008/0174444 A1Published application

Dual acceleration sensor system

AssigneeHitachi Metals, Ltd.

InventorsMasaru NODA, Masakazu Sugimoto

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Abstract

Provided is a dual acceleration sensor system usable for detecting impact, when strong impact works on a mobile device, and recording a history of applied impact, and workable with a low power consumption. It contains low range and high range acceleration sensors, a signal processing circuit, and/or an operation mode controller for switching signal between the two sensors and an operation mode of the signal processing circuit. The operation mode controller switches between a low range mode in which a signal from the low range acceleration sensor is processed at a low range operation rate and a high range mode in which a signal from the high range acceleration sensor is processed at a high range operation rate. It is judged whether data processed in the low range mode exceeds a first threshold or not, and if not, the low range mode continues, while the mode switches to the high range mode if it does. In the high range mode, when a state that the data is less than a second threshold continues for a predetermined period of time, the mode returns to the low range mode, and if not, the high range mode remains.

Claims7

Dependent claims

A dual acceleration sensor system comprising:

a low range acceleration sensor that detects a relatively low acceleration;
a high range acceleration sensor that detects a relatively high acceleration;
a signal processing circuit that operates in a low range mode, in which the signal processing circuit processes signals detected by the low range acceleration sensor in an operation rate for a low range, and in a high range mode, in which the signal processing circuit processes signals detected by the high range acceleration sensor in an operation rate for a high range;
and
an operation mode controller that switches signals which the signal processing circuit processes between the two acceleration sensors and an operation mode between the low range mode and the high range mode;
wherein it is judged in the low range mode whether signal-processed data exceeds a first threshold or not, and the low range mode remains if not, while the operation mode is switched to the high range mode if it does, and
when a signal-processed data in the high range mode continues less than a second threshold for a predetermined period of time, the operation mode returns to the low range mode, while the high range mode remains, if a period that the signal-processed data is less than the second threshold does not reach the predetermined period of time.

4 more elements

Dependencies are inferred from the claim text.