Touch panel control circuit and semiconductor integrated circuit using the same

Patent metadata

Field	Value
Publication number	US-9811219-B2
Application number	US-201414581810-A
Country	US
Kind code	B2
Filing date	Dec 23, 2014
Priority date	Dec 25, 2013
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

A touch panel control circuit includes a plurality of drive circuits which are connected to Y sensor electrodes, respectively, and which apply a plurality of pulses to a corresponding Y sensor electrode for every predetermined period, and a plurality of detection circuits which are connected to X sensor electrodes, respectively. Each of the detection circuits includes a switched capacitor circuit that continues sampling of a signal from each of the X sensor electrodes, to which the detection circuits are connected, not only at a timing that is in synchronization with the plurality of pulses that are applied to the Y sensor electrodes, but also at a timing at which the pulses are not applied to the Y sensor electrodes. For example, the switched capacitor circuit is an integration circuit, or an integration circuit with a finite impulse response (FIR) filter or an infinite impulse response (IIR) filter.

First claim

What is claimed is:

1. A touch panel control circuit configured to be connected to a touch panel in which an intersection capacitor is formed at each of a plurality of intersections at which a plurality of Y sensor electrodes and a plurality of X sensor electrodes intersect each other, the touch panel control circuit comprising:
a plurality of drive circuits connected to the plurality of Y sensor electrodes, respectively, and each configured to apply a plurality of pulses to a corresponding one of the Y sensor electrodes; and
a plurality of detection circuits connected to the plurality of X sensor electrodes, respectively,
wherein each of the detection circuits includes a switched capacitor circuit configured to perform sampling of a signal from each of the X sensor electrodes, to which the detection circuits are connected,
wherein the touch panel is mounted so as to overlap a display panel, and the touch panel control circuit is configured to perform timing control of providing a display drive period of the display panel and a touch detection period of the touch panel in each line period,
wherein the plurality of drive circuits are configured to output the pulses in the touch detection period and to stop output of the pulses in the display drive period, and
wherein each of the plurality of detection circuits is configured to allow the switched capacitor circuit to continue the operation of sampling the signal from each of the X sensor electrodes in the display drive period and the touch detection period.

2. The touch panel control circuit according to claim 1 , further comprising:
a sequence control circuit configured to control each of the plurality of drive circuits and a respective one of the plurality of detection circuits in synchronization with a same clock signal.

3. The touch panel control circuit according to claim 1 , wherein the operation of sampling the signal from the X sensor electrodes by the switched capacitor circuit continues in the predetermined period at a predetermined cycle.

4. The touch panel control circuit according to claim 1 , further comprising:
a sequence control circuit configured to control one of the plurality of drive circuits and a respective one of the plurality of detection circuits in synchronization with a same clock signal,
wherein the touch detection period is controlled based on at least one of a horizontal synchronization signal of an image displayed on the display panel, and timing control information based on the horizontal synchronization signal is input to the touch panel control circuit, and
wherein the sequence control circuit is configured to allow the switched capacitor circuit to continue the operation of sampling the signal from the X sensor electrodes in the display drive period and the touch detection period at a predetermined cycle based on the clock signal, output the pulses from the drive circuit in the touch detection period at the predetermined cycle based on the clock, and stop the output of the pulses from the drive circuit in the display drive period.

5. The touch panel control circuit according to claim 4 ,
wherein the timing control information includes first information that specifies a period to initiation of the display drive period from the horizontal synchronization signal, second information that specifies a period to initiation of the touch detection period from the horizontal synchronization signal, and third information that specifies a cycle of the pulses and a high-period.

6. The touch panel control circuit according to claim 5 ,
wherein the touch panel control circuit includes a storage device configured to store at least one of the first information, the second information, and the third information.

7. The touch panel control circuit according to claim 1 ,
wherein the switched capacitor circuit includes an integration circuit connected to the X sensor electrodes in the predetermined period in synchronization with the pulses, and is also connected to the X sensor electrodes in a period in which the pulses are not input to accumulatively add signal charges that are input from the X sensor electrodes.

8. The touch panel control circuit according to claim 7 ,
wherein the integration circuit is connected to the X sensor electrodes in periods in accordance with a rising edge and a falling edge of the pulses, respectively, and is connected to the X sensor electrodes in periods in accordance with a rising edge and a falling edge when assuming that the pulses continue at a cycle as is even in a period in which the pulses are not applied to the Y sensor electrodes to perform the accumulative addition by inverting a polarity when adding a signal charge that is input in the period corresponding to the rising edge and a polarity when adding a signal charge that is input in the period corresponding to the falling edge from each other.

9. The touch panel control circuit according to claim 1 ,
wherein the switched capacitor circuit includes a switched capacitor filter which is connected to the X sensor electrodes in the predetermined period in synchronization with the pulses, and is connected to the X sensor electrodes in a period in which the pulses are not applied to the Y sensor electrodes to perform a filtering process with respect to a signal charge that is input from the X sensor electrodes, and an integration circuit configured to accumulatively add an output of the switched capacitor filter.

10. A touch panel control circuit configured to be connected to a touch panel in which an intersection capacitor is formed at each of a plurality of intersections at which a plurality of Y sensor electrodes and a plurality of X sensor electrodes intersect each other, the touch panel control circuit comprising:
a plurality of drive circuits connected to the plurality of Y sensor electrodes, respectively, and configured to apply a plurality of pulses to a corresponding Y sensor electrode for a predetermined period; and
a plurality of detection circuits connected to the plurality of X sensor electrodes, respectively,
wherein each of the detection circuits includes a switched capacitor circuit configured to perform sampling of a signal from each of the X sensor electrodes, to which the detection circuits are connected, at a timing that is in synchronization with the plurality of pulses, and at a timing at which the plurality of pulses are not applied to the Y sensor electrodes in the predetermined period,
wherein the switched capacitor circuit includes a switched capacitor filter which is connected to the X sensor electrodes in the predetermined period in synchronization with the pulses, and is connected to the X sensor electrodes in a period in which the pulses are not applied to the Y sensor electrodes to perform a filtering process with respect to a signal charge that is input from the X sensor electrodes, and an integration circuit configured to accumulatively add an output of the switched capacitor filter, and
wherein the switched capacitor filter is connected to the X sensor electrodes in periods in accordance with a rising edge and a falling edge of the pulses, respectively, and is connected to the X sensor electrodes in periods in accordance with a rising edge and a falling edge when assuming that the pulses continue at a cycle as is even in a period in which the pulses are not applied to the Y sensor electrodes to perform the filtering process by inverting a polarity when adding a signal charge that is input in the period corresponding to the rising edge and a polarity when adding a signal charge that is input in the period corresponding to the falling edge from each other.

11. A touch panel control circuit configured to

Assignees

• Synaptics Japan Gk

Inventors

• Noto Takayuki

Classifications

• G06F3/044 Primary

  by capacitive means · CPC title

• G06F3/0412 Primary

  Digitisers structurally integrated in a display · CPC title

• G06F3/04184

  Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally · CPC title

• G06F3/04182

  Filtering of noise external to the device and not generated by digitiser components · CPC title

• G06F3/0446

  using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes · CPC title