Position detecting device

摘要

A position detecting device is provided, which is capable of stably detecting an indicator with less susceptibility to the influence of noise by using a differential amplifier circuit and multi-touch. The device includes a sensor having an electrode pattern formed of plural first electrodes arranged in a first direction and plural second electrodes arranged in a second direction. The device selects two sets of the first electrodes separate from each other by a distance equivalent to a predetermined number of electrodes and supplies two drive signals having phases inverted from each other. The device selects two sets of the second electrodes separate from each other by a distance equivalent to a predetermined number of electrodes and connects the selected second electrodes to two differential inputs of a differential amplifier circuit. The device controls selection of two sets of the first electrodes and two sets of the second electrodes.

主权项

1. A position detecting device including a sensor having an electrode pattern formed of a plurality of first electrodes arranged in a first direction and a plurality of second electrodes arranged in a second direction intersecting with the first direction, the position detecting device supplying a drive signal to the first electrodes and detecting a position of an indicator on the electrode pattern from a reception signal obtained from the second electrodes, the position detecting device comprising:
a first selection circuit configured to select two sets of the second electrodes, which are separate from each other by a distance equivalent to a second predetermined number of electrodes, from the plurality of second electrodes; a second selection circuit configured to select two sets of the first electrodes, which are separate from each other by a distance equivalent to a first predetermined number of electrodes, from the plurality of first electrodes; a drive signal supply circuit configured to supply the drive signal to each of the two sets of the first electrodes selected by the second selection circuit by outputting two signals having phases inverted from each other; a differential amplifier circuit having a non-inverting input terminal, to which one set of the two sets of the second electrodes selected by the first selection circuit is connected, and an inverting input terminal, to which the other set of the two sets of the second electrodes is connected; a detection circuit configured to detect the position of the indicator on the electrode pattern from an output signal of the differential amplifier circuit; and a control circuit that controls selection by the first and second selection circuits by determining the first and second predetermined numbers in such a manner that, when positions of plural indicators are detected by the detection circuit, only one intersection among four intersections, which are respectively formed by the two sets each of electrodes selected by the first and second selection circuits, is near the position of one of the plural indicators and the three other intersections are not near any of the plural indicators.