Capacitance detection device

Abstract

Provided is a capacitance detection device capable of detecting occurrence of human manipulation with a simple configuration by distinguishing well between changes in capacitance due to external elements such as water droplets and human manipulation. The first opening and closing control and the second opening and closing control for performing the second switching operation at different charging times are alternately and repeatedly performed. The number of repetitions of the second switching operation until the potential of the terminal of the reference capacitor changes to the set potential in the two switching controls is counted. Based on the number of repetitions in at least one of the two on-off controls, it is judged whether the measured capacitance has changed, and based on the number of repetitions in the two on-off controls, it is judged whether the change in the measured capacitance is caused by events on the detected object.

Description

technical field [0001] The present invention relates to an electrostatic capacitance detection device for detecting unknown capacitance to be measured. Background technique [0002] There is known a locking system in which a hand-held device carried by a user communicates with a host on a vehicle, thereby authenticating the hand-held device, thereby controlling the automatic unlocking and locking of the vehicle doors ( smart entry system). In the description of US2007 / 0216175A1 (Patent Document 1), the following vehicle door handle technology is described: after the hand-held device is authenticated between the vehicle-mounted device and the hand-held device, by detecting that the user touches the door handle installed on the door, etc. A vehicle door handle technology for locking / unlocking the doors by operating the door handle by the user. The door handle incorporates a capacitive detection device or the like for detecting that a human hand approaches or touches the door...

AI Technical Summary

Problems solved by technology

However, at the moment when water, etc. adheres to the capacitance to be measured, it may not be possible to distinguish between human contact and water, etc.

For example, when the electrostatic capacitance detection device mounted on the door handle of the locking system like Patent Document 1 comes into contact with water due to rain or car washing, there is a possibility of locking / unlocking irrespective of the user's will to lock / unlock. door possibility

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