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 orthogonal code signals, each having a predetermined time difference from each other, based on a code string having an orthogonal characteristic, each of the plurality of orthogonal code signals being configured to be supplied as a unit to the conductor pattern;
(c) a transmission conductor selection circuit configured to selectively supply the plurality of orthogonal code signals produced by the code string signal production circuit to the plurality of first conductors, by supplying each of the plurality of orthogonal code signals to at least two of the first conductors simultaneously for a length of the signal, to increase a reception signal level due to said each of the plurality of orthogonal code signals so as to expand a detection range for the pointer;
(d) a reception conductor selection circuit configured to selectively receive signals from the plurality of second conductors generated in response to the plurality of orthogonal code signals supplied to the plurality of first conductors;
(e) a signal detection circuit configured to detect a signal corresponding to a variation of capacitance caused between the conductor pattern and a pointer, based on the signals from the plurality of second conductors received via the reception conductor selection circuit;
(f) 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;
(g) a correlation detection circuit configured to determine correlation values between code strings provided for correlation and the digital signal comprising a word string formed of a plurality of bits output from the analog to digital conversion circuit;
(h) a memory circuit configured to store the correlation values output from the correlation detection circuit; and
(i) a position calculation circuit configured to calculate a position on the conductor pattern pointed to by the pointer based on the correlation values.
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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.
55 Citations
24 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 orthogonal code signals, each having a predetermined time difference from each other, based on a code string having an orthogonal characteristic, each of the plurality of orthogonal code signals being configured to be supplied as a unit to the conductor pattern; (c) a transmission conductor selection circuit configured to selectively supply the plurality of orthogonal code signals produced by the code string signal production circuit to the plurality of first conductors, by supplying each of the plurality of orthogonal code signals to at least two of the first conductors simultaneously for a length of the signal, to increase a reception signal level due to said each of the plurality of orthogonal code signals so as to expand a detection range for the pointer; (d) a reception conductor selection circuit configured to selectively receive signals from the plurality of second conductors generated in response to the plurality of orthogonal code signals supplied to the plurality of first conductors; (e) a signal detection circuit configured to detect a signal corresponding to a variation of capacitance caused between the conductor pattern and a pointer, based on the signals from the plurality of second conductors received via the reception conductor selection circuit; (f) 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; (g) a correlation detection circuit configured to determine correlation values between code strings provided for correlation and the digital signal comprising a word string formed of a plurality of bits output from the analog to digital conversion circuit; (h) a memory circuit configured to store the correlation values output from the correlation detection circuit; and (i) a position calculation circuit configured to calculate a position on the conductor pattern pointed to by the pointer based on the correlation 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)
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24. 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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producing a plurality of orthogonal code signals, each having a predetermined time difference from each other, based on a code string having an orthogonal characteristic, each of the plurality of orthogonal code signals being configured to be supplied as a unit to the conductor pattern; selectively supplying the plurality of orthogonal code signals to the plurality of first conductors of the conductor pattern, by supplying each of the plurality of orthogonal code signals to at least two of the first conductors simultaneously for a length of the signal, to increase a reception signal level due to said each of the plurality of orthogonal code signals so as to expand a detection range for the pointer; selecting a portion of the second conductors from which signals are to be received; detecting a signal corresponding to a variation of capacitance caused between the conductor pattern and a pointer based on the signals received from the selectively switched second conductors; 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 comprising a word formed of a plurality of bits obtained by the conversion; storing the correlation values; and detecting the pointer position based on the correlation values.
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Specification