Patent ID: 8692779

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 orthogonal code signals, each having a predetermined time difference from each other, based on a code string having an orthogonal characteristic, and to supply the produced plurality of orthogonal code signals to the plurality of first conductors; (c) a signal detection circuit configured to be connected to the plurality of second conductors to 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, 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 correlation values; wherein a number of the plurality of orthogonal code signals to be produced by the code string signal production circuit is 4N−1 each having the same chip length, N being an integer equal to or greater than 2, and the code string signal production circuit is further configured to produce a determined number of compensation signal(s), the number of the compensation signal(s) being less than 4N−1 and set such that the sum of 4N−1 and the number of the compensation signal(s) is an even number and a sum total of signal values output from the plurality of second conductors becomes zero in case the pointer is not present on the conductor pattern.