Capacitive touch panel device with differing drive pulse widths
First Claim
Patent Images
1. A semiconductor device comprising:
- a touch panel controller for a touch panel having a plurality of drive electrodes, a plurality of detection electrodes, and a plurality of crossing parts formed by the drive and detection electrodes, the touch panel controller comprisinga drive circuit which outputs drive pulses to drive terminals connected to the drive electrodes respectively in a predetermined order; and
a detection circuit which accepts signals arising from the detection electrodes in response to the drive pulses supplied to the drive electrodes, as inputs through detection terminals connected to the detection electrodes, and produces detection data corresponding to a fluctuation in capacitive coupling state at each crossing part,a capacitance-connecting node at which an output of a buffer is connected to an input stage of the detection circuit through a capacitance; and
a control circuit,wherein the drive circuit has more than one kind of outputtable pulse width for each kind of pulse signal period of the outputtable drive pulses, andwherein before outputting the drive pulses to the drive terminals, the control circuit controls the buffer to output more than one kind of pulse having the same pulse width as those of the drive pulses, controls the detection circuit to produce pseudo detection data in response to signals supplied through the capacitance-connecting node, and controls the drive circuit to output a drive pulse having a pulse width decided based on the pseudo detection data.
6 Assignments
0 Petitions
Accused Products
Abstract
It becomes possible to use drive pulses having different pulse widths for one kind of drive pulse signal period. Therefore, even if a voltage acting on a crossing part of drive and detection electrodes is periodically changed through a stray capacitance attributed to an external object such as a finger in an undesired manner, the pulse width of the drive pulse is never fixed with respect to the period, and the periodic buildup of a certain voltage on a detection signal, which would make appreciable noise, is suppressed. Thus, the reduction of detection signals can be suppressed in quantity without switching the pulse signal frequency of the drive pulse of a touch panel.
-
Citations
13 Claims
-
1. A semiconductor device comprising:
-
a touch panel controller for a touch panel having a plurality of drive electrodes, a plurality of detection electrodes, and a plurality of crossing parts formed by the drive and detection electrodes, the touch panel controller comprising a drive circuit which outputs drive pulses to drive terminals connected to the drive electrodes respectively in a predetermined order; and a detection circuit which accepts signals arising from the detection electrodes in response to the drive pulses supplied to the drive electrodes, as inputs through detection terminals connected to the detection electrodes, and produces detection data corresponding to a fluctuation in capacitive coupling state at each crossing part, a capacitance-connecting node at which an output of a buffer is connected to an input stage of the detection circuit through a capacitance; and a control circuit, wherein the drive circuit has more than one kind of outputtable pulse width for each kind of pulse signal period of the outputtable drive pulses, and wherein before outputting the drive pulses to the drive terminals, the control circuit controls the buffer to output more than one kind of pulse having the same pulse width as those of the drive pulses, controls the detection circuit to produce pseudo detection data in response to signals supplied through the capacitance-connecting node, and controls the drive circuit to output a drive pulse having a pulse width decided based on the pseudo detection data. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. An electronic device comprising:
-
a touch panel controller for a touch panel having a plurality of drive electrodes, a plurality of detection electrodes, and a plurality of crossing parts formed by the drive and detection electrodes; and a processor connected with the touch panel controller, wherein the touch panel controller includes a drive circuit which outputs drive pulses to drive terminals connected to the drive electrodes respectively in a predetermined order, and a detection circuit which accepts signals arising from the detection electrodes in response to the drive pulses supplied to the drive electrodes, as inputs through detection terminals connected to the detection electrodes, and produces detection data corresponding to a fluctuation in capacitive coupling state at each crossing part, wherein the drive circuit has more than one kind of outputtable pulse width for each kind of pulse signal period of the outputtable drive pulse, wherein the device further comprises a capacitance-connecting node at which an output of a buffer is connected to an input stage of the detection circuit through a capacitance; and a control circuit, wherein before outputting the drive pulses to the drive terminals, the control circuit controls the buffer to output more than one kind of pulse having the same pulse width as those of the drive pulses, and controls the detection circuit to produce pseudo detection data in response to signals supplied through the capacitance-connecting node, wherein the processor identifies the pulse width which minimizes a difference between the pseudo detection data detected by the detection circuit and data in the case of the capacitance having a predetermined value, and notifies the control circuit of the identified pulse width, and wherein the control circuit controls the drive circuit to output drive pulses with the pulse width notified to the drive circuit. - View Dependent Claims (8, 9, 10, 11, 12, 13)
-
Specification