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Input state detection device

  • US 10,133,413 B2
  • Filed: 07/28/2015
  • Issued: 11/20/2018
  • Est. Priority Date: 07/30/2013
  • Status: Active Grant
First Claim
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1. An input state detection device for detecting contact or pressing of an electrically conductive object, comprising:

  • an electrostatic capacitive sensor having a first electrode attached to a substrate, a second electrode located on a side of the electrically conductive object to be contacted, and a dielectric layer placed between the first electrode and the second electrode and to be compressed by pressing force applied on the second electrode by the electrically conductive object;

    a constant-voltage power supply device having a voltage application terminal connected to a side of the electrostatic capacitive sensor and applying a predetermined voltage to the electrostatic capacitive sensor;

    a detector connected in series with the electrostatic capacitive sensor, having a detection terminal connected to the side of the electrostatic capacitive sensor, and detecting an electric current flowing from the detection terminal that changes with electrostatic capacitance of the electrostatic capacitive sensor and electrostatic capacitance of the electrically conductive object;

    a state switching switch that changes a configuration of the input state detection device between a first configuration and a second configuration,wherein in the first configuration, the input state detection device is configured such that the voltage application terminal of the constant-voltage power supply device is connected to a side of the first electrode and the detection terminal of the detector is connected to a side of the second electrode, andwherein in the second configuration, the input state detection device is configured such that the voltage application terminal of the constant-voltage power supply device is connected to the side of the second electrode and the detection terminal of the detector is connected to the side of the first electrode;

    an input detector for detecting (i) whether the electrically conductive object is in a non-contact state, or in a contact but not pressing state, with respect to a surface of the electrostatic capacitive sensor on the side of the second electrode, based on a value detected by the detector with the state switching switch set to the first configuration of the input state detection device, and (ii) whether the electrically conductive object is in the contact but not pressing state, or in a pressing state, with respect to the second electrode, based on a value detected by the detector with the state switching switch set to the second configuration of the input state detection device,wherein the predetermined voltage applied by the constant-voltage power supply device is a cyclic voltage, andwherein the input detector is an ammeter for detecting the electric current flowing from the detection terminal, and (i) when the input state detection device is in the first configuration, the input detector detects the electric currently flowing from the side of the second electrode, and (ii) when the input state detection device is in the second configuration, the input detector detects the electric currently flowing from the side of the first electrode.

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