Patent ID: 8587534

Claim:
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.