Touch sensor identifying a body part
First Claim
1. A touch sensor for sensing a touch of a body part, comprising:
- an oscillator which outputs a high-frequency signal;
an electrode unit comprising a pair of electrodes which applies said high-frequency signal from said oscillator unit to the body part;
a detector unit which detects a variety of impedance value varied by said body part contacting said pair of electrodes, and outputs an output signal based on said variety of impedance values; and
a discriminator unit which determines whether said body part is in contact with said pair of electrodes by comparing said output signal from said detector unit with a predetermined reference value, wherein a capacitance between the body part and said pair of electrodes increases when the body part is in contact with said pair of electrodes, and a total resistance value of a high-frequency impedance real value of the part of the body part and a circuit resistance value including said pair of electrodes matches an output impedance at a predetermined frequency of said oscillator, allowing said discriminator unit to determine that the contact is that of the body part.
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Accused Products
Abstract
A touch sensor which is able to detect the touch of a finger with reasonable accuracy. In this touch sensor, the oscillator unit supplies a high-frequency signal to the electrode unit. If the item detected is a biological entity of a human body such as a finger, the impedance of the electrode unit will change. The impedance is initially matched to that on the input side of the electrode when the finger is in touch with the electrodes. The reflected wave will be smaller because of the matching of impedance when the finger is in touch with the electrode. By detecting this reflected wave and comparing it with a reference signal in the discriminator unit, it can be determined that the reflection level is lower and so a conclusion can be made that the electrode is touched by a person.
56 Citations
37 Claims
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1. A touch sensor for sensing a touch of a body part, comprising:
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an oscillator which outputs a high-frequency signal;
an electrode unit comprising a pair of electrodes which applies said high-frequency signal from said oscillator unit to the body part;
a detector unit which detects a variety of impedance value varied by said body part contacting said pair of electrodes, and outputs an output signal based on said variety of impedance values; and
a discriminator unit which determines whether said body part is in contact with said pair of electrodes by comparing said output signal from said detector unit with a predetermined reference value, wherein a capacitance between the body part and said pair of electrodes increases when the body part is in contact with said pair of electrodes, and a total resistance value of a high-frequency impedance real value of the part of the body part and a circuit resistance value including said pair of electrodes matches an output impedance at a predetermined frequency of said oscillator, allowing said discriminator unit to determine that the contact is that of the body part. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A method of sensing a body part comprising:
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outputting a high-frequency signal;
applying said high-frequency signal from an oscillator unit to the body part;
detecting a variety of impedance values varied by said body part contacting a pair of electrodes, and which outputs and output signal based on said variety of impedance values; and
determining whether said body part is in contact with said pair of electrodes by comparing said output signal with a predetermined reference value, wherein a capacitance between the body part and said pair of electrodes increases when the body part is in contact with said pair of electrodes, and a total resistance value of a high-frequency impedance real value of the part of the body part and a circuit resistance value including said pair of electrodes matches an output impedance at a predetermined frequency of said oscillator, allowing said discriminator unit to determine that the contact is that of the body part.
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36. A touch sensor for sensing an object, comprising:
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a first unit applying a high frequency signal to the object and detecting multiple impedance values, and outputting a signal based on the multiple impedance values; and
a second unit determining whether the object is in contact with electrodes by comparing the signal with a predetermined reference value, wherein a capacitance between the body part and said pair of electrodes increases when the body part is in contact with said electrodes, and a total resistance value of a high-frequency impedance real value of the part of the body part and a circuit resistance value including said electrodes match an output impedance at a predetermined frequency of said oscillator, allowing said discriminator unit to determine that the contact is that of the body part.
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37. A method of sensing an object, comprising:
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applying a high frequency signal to the object and detecting multiple impedance values, and outputting a signal based on the multiple impedance values; and
determining whether the object is in contact with electrodes by comparing the signal with a predetermined reference value, wherein a capacitance between the body part and said pair of electrodes increases when the body part is in contact with said pair of electrodes, and a total resistance value of a high-frequency impedance real value of the part of the body part and a circuit resistance value including said electrodes match an output impedance at a predetermined frequency of said oscillator, allowing said discriminator unit to determine that the contact is that of the body part.
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Specification