Pointer detection apparatus and pointer detection method
First Claim
1. A pointer position detection apparatus, comprising:
- (a) a conductor pattern including a plurality of first conductors disposed in a first direction and a plurality of second conductors disposed in a second direction which crosses the first direction;
(b) a code string signal production circuit configured to produce a plurality of modulated orthogonal code signals by modulating a plurality of orthogonal code signals, the plurality of orthogonal code signals having a predetermined time difference from each other and being produced based on a code string that has an orthogonal characteristic, each of the plurality of modulated orthogonal code signals being configured to be supplied as a unit to the conductor pattern, the code string signal production circuit being further configured to produce at least one inverted code signal having a phase inverted from at least one of the plurality of modulated orthogonal code signals for a length of the signal and to supply the produced plurality of modulated orthogonal code signals and said at least one inverted code signal to the plurality of first conductors, wherein said at least one of the plurality of modulated orthogonal code signals is supplied to at least two of the first conductors that are adjacent to another one of the first conductors to which said at least one inverted code signal is supplied;
(c) a signal detection circuit configured to be connected to the plurality of second conductors to receive and demodulate signals from the plurality of second conductors generated in response to the plurality of modulated orthogonal code signals supplied to the plurality of first conductors, and to detect and output a signal corresponding to a variation of capacitance caused between the conductor pattern and a pointer;
(d) an analog to digital conversion circuit configured to convert the signal output from the signal detection circuit into a digital signal comprising a word string formed of a plurality of bits;
(e) a correlation detection circuit configured to determine correlation values between code strings provided for correlation and the word string output from the analog to digital conversion circuit;
(f) a memory circuit configured to store the correlation values, each having a plurality of bits output from the correlation detection circuit; and
(g) a position calculation circuit configured to calculate a position on the conductor pattern pointed to by the pointer based on the correlated values.
1 Assignment
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Accused Products
Abstract
A pointer detection apparatus includes a conductor pattern with first conductors disposed in a first direction and second conductors disposed in a second direction that crosses the first direction, and a code string signal production circuit for producing signals based on orthogonal code strings with phases different from each other and supplying the produced signals to the first conductors. The apparatus also includes a signal detection circuit connected to the second conductors for detecting a signal corresponding to a variation of electrostatic capacitance between the conductor pattern and a pointer, an analog to digital conversion (ADC) circuit for converting the signal output from the signal detection circuit into a digital signal comprising a word string of multiple bits, and a correlation detection circuit for determining correlation values between the code strings and the word string. The apparatus also includes a memory for storing correlation values successively output from the correlation detection circuit, wherein the pointer is detected based on the correlation values.
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Citations
27 Claims
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1. A pointer position detection apparatus, comprising:
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(a) a conductor pattern including a plurality of first conductors disposed in a first direction and a plurality of second conductors disposed in a second direction which crosses the first direction; (b) a code string signal production circuit configured to produce a plurality of modulated orthogonal code signals by modulating a plurality of orthogonal code signals, the plurality of orthogonal code signals having a predetermined time difference from each other and being produced based on a code string that has an orthogonal characteristic, each of the plurality of modulated orthogonal code signals being configured to be supplied as a unit to the conductor pattern, the code string signal production circuit being further configured to produce at least one inverted code signal having a phase inverted from at least one of the plurality of modulated orthogonal code signals for a length of the signal and to supply the produced plurality of modulated orthogonal code signals and said at least one inverted code signal to the plurality of first conductors, wherein said at least one of the plurality of modulated orthogonal code signals is supplied to at least two of the first conductors that are adjacent to another one of the first conductors to which said at least one inverted code signal is supplied; (c) a signal detection circuit configured to be connected to the plurality of second conductors to receive and demodulate signals from the plurality of second conductors generated in response to the plurality of modulated orthogonal code signals supplied to the plurality of first conductors, and to detect and output a signal corresponding to a variation of capacitance caused between the conductor pattern and a pointer; (d) an analog to digital conversion circuit configured to convert the signal output from the signal detection circuit into a digital signal comprising a word string formed of a plurality of bits; (e) a correlation detection circuit configured to determine correlation values between code strings provided for correlation and the word string output from the analog to digital conversion circuit; (f) a memory circuit configured to store the correlation values, each having a plurality of bits output from the correlation detection circuit; and (g) a position calculation circuit configured to calculate a position on the conductor pattern pointed to by the pointer based on the correlated values. - 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)
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26. A method for detecting a pointer position by a pointer detection apparatus having a conductor pattern that includes a plurality of first conductors disposed in a first direction and a plurality of second conductors disposed in a second direction which crosses the first direction, the method comprising:
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supplying a plurality of modulated orthogonal code signals, which are produced by modulating a plurality of orthogonal code signals, the plurality of orthogonal code signals having a predetermined time difference from each other and being based on a code string that has an orthogonal characteristic, each of the modulated orthogonal code signals being configured to be supplied as a unit to the conductor pattern, and at least one inverted code signal, which is produced by inverting a phase of at least one of the plurality of modulated orthogonal code signals for a length of the signal, to the plurality of first conductors of the conductor pattern, wherein said at least one of the plurality of modulated orthogonal code signals is supplied to at least two of the first conductors that are adjacent to another one of the first conductors to which said at least one inverted code signal is supplied; detecting a signal corresponding to a variation of electrostatic capacitance caused between the conductor pattern and a pointer; converting the detected signal into a digital signal comprising a word formed of a plurality of bits; determining correlation values between code strings provided for correlation and the digital signal obtained by the conversion; storing the correlation values; and detecting the pointer position based on the correlation values.
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27. A pointer position detection apparatus, comprising:
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(a) a conductor pattern including a plurality of first conductors disposed in a first direction and a plurality of second conductors disposed in a second direction which crosses the first direction; (b) a code string signal production circuit configured to produce a plurality of modulated orthogonal code signals by modulating a plurality of orthogonal code signals, the plurality of orthogonal code signals having a predetermined time difference from each other and being produced based on a code string that has an orthogonal characteristic, and to produce, for at least one of the plurality of modulated orthogonal code signals, at least one inverted code signal having a phase inverted from that of said at least one of the plurality of modulated orthogonal code signals, and to supply the produced plurality of modulated orthogonal code signals and said at least one inverted code signal to the plurality of first conductors, wherein a first conductor interposed between another first conductor, to which said at least one of the plurality of modulated orthogonal code signals is supplied, and yet another first conductor, to which said at least one inverted code signal is supplied, is connected to ground; (c) a signal detection circuit configured to be connected to the plurality of second conductors to receive and demodulate signals from the plurality of second conductors generated in response to the plurality of modulated orthogonal code signals supplied to the plurality of first conductors, and to detect and output a signal corresponding to a variation of capacitance caused between the conductor pattern and a pointer; (d) an analog to digital conversion circuit configured to convert the signal output from the signal detection circuit into a digital signal comprising a word string formed of a plurality of bits; (e) a correlation detection circuit configured to determine correlation values between code strings provided for correlation and the word string output from the analog to digital conversion circuit; (f) a memory circuit configured to store the correlation values, each having a plurality of bits output from the correlation detection circuit; and (g) a position calculation circuit configured to calculate a position on the conductor pattern pointed to by the pointer based on the correlated values.
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Specification