Semiconductor device and electronic device

1. A semiconductor device comprising:

a touch panel controller connected with a touch panel having a plurality of drive electrodes, a plurality of detection electrodes, and a plurality of capacitance components formed at intersections of the drive and detection electrodes,

wherein the touch panel controller comprises

a plurality of drive terminals connected with the plurality of drive electrodes;

a drive circuit operable to output a drive pulse from the plurality of drive terminals;

a plurality of detection terminals connected with the plurality of detection electrodes;

a detection circuit operable to create detection data by accumulating signals input through each detection terminal in synchronization with change in the drive pulse; and

a control circuit operable to control an action of detecting a touch and no touch by use of the drive circuit and the detection circuit, and

wherein the detection circuit has a two-edge detection mode for creating detection data by accumulating, in terms of absolute value components, signals which are input through each detection terminal in synchronization with rising and falling changes of the drive pulse respectively and alternately change in polarity.

2. The semiconductor device according to claim 1 , wherein the detection circuit comprises:

an integration circuit configured to integrate a signal input through each detection terminal; and

an analog-to-digital conversion circuit configured to convert an analog signal resulting from the integration by the integration circuit into a digital signal to produce the detection data,

wherein the integration circuit has an operational amplifier, an integration capacitance, and a switching circuit configured to invert a connection of the integration capacitance between an inverting input terminal of the operational amplifier and an output terminal thereof by switching the connection of the integration capacitance between the inverting input terminal of the operational amplifier and the output terminal thereof, and

wherein the control circuit switches the connection of the switching circuit immediately before rising and falling changes of the drive pulse.

3. The semiconductor device according to claim 2 ,

wherein an initial voltage of an output terminal of the integration circuit in the action of detecting a touch and no touch is a voltage close to a center value of an input range of the analog-to-digital conversion circuit.

4. The semiconductor device according to claim 3 ,

wherein when a capacitance component of the intersection has been reduced by a touch, multiple-pulse driving is performed on the drive electrodes by a drive pulse, and the driving is terminated at a falling edge of the pulse, to cause a signal voltage obtained in the integration circuit to be equal to or lower than an upper limit of the input range of the analog-to-digital conversion circuit; and

wherein, when the capacitance component of the intersection has not been reduced because of no touch, multiple-pulse driving is performed on the drive electrodes by a drive pulse, and the driving is terminated at a falling edge of the pulse, to cause a signal voltage obtained in the integration circuit to be lower than a signal voltage in the touched condition.

5. The semiconductor device according to claim 3 ,

wherein, when the capacitance component of the intersection has been reduced by a touch, multiple-pulse driving is performed on the drive electrodes by a drive pulse, and the driving is terminated at a rising edge of the pulse, to cause a signal voltage obtained in the integration circuit to be equal to or higher than a lower limit of the input range of the analog-to-digital conversion; and

wherein, when the capacitance component of the intersection has not been reduced because of no touch, multiple-pulse driving is performed on the drive electrodes by a drive pulse, and the driving is terminated at a rising edge of the pulse, to cause a signal voltage obtained in the integration circuit to be higher than a signal voltage in the touched condition.

6. The semiconductor device according to claim 3 , further comprising:

a register configured to provide an instruction on which of first and second driving-termination modes should be selected,

wherein in the first driving-termination mode, driving by a drive pulse is terminated at a rising edge of the drive pulse, and in the second driving-termination mode, driving by a drive pulse is terminated at a falling edge of the drive pulse.

7. The semiconductor device according to claim 6 , wherein the register is a rewritable register provided in the control circuit.

8. The semiconductor device according to claim 3 , further comprising:

a display panel controller configured to output a scan pulse and a signal voltage to scan and signal electrodes of a display panel respectively, wherein the display panel has a plurality of liquid crystal display cells disposed at intersections of the scan and signal electrodes.

9. The semiconductor device according to claim 8 ,

wherein the control circuit controls the drive pulse in timing of change so that a timing of when the scan pulse changes and a timing of when the signal voltage changes are included in a period between rising and falling edges of the drive pulse.

10. The semiconductor device according to claim 9 , further comprising:

a separation switch configured to separate the detection circuit from the detection terminal in every predetermined period including a timing when the scan pulse changes and a timing when the signal voltage changes.

11. The semiconductor device according to claim 2 ,

wherein the control circuit is configured to detect a touch and no touch by

initializing an inverting input terminal of the operational amplifier and its output terminal using a first voltage supplied, as a reference voltage, to a non-inverting input terminal of the operational amplifier;

providing the drive electrode with a drive pulse with a predetermined pulse number;

switching connection of the integration capacitance with a timing immediately before an edge change of the drive pulse; and

converting, by the analog-to-digital conversion circuit, a signal subjected to integration by the integration capacitance in synchronization with each edge change of the drive pulse into a digital signal to create detection data.

12. The semiconductor device according to claim 1 ,

wherein the detection circuit further has a one-edge detection mode in which detection data is created by accumulating a signal input through the detection terminal more than one time in synchronization with any one of a rising change and a falling change of the drive pulse, and

wherein the semiconductor device further comprises a register configured to instruct which of the two-edge detection mode and the one-edge detection mode to select.

13. The semiconductor device according to claim 12 , wherein the register is a rewritable mode register provided in the control circuit.

14. An electronic device comprising:

a touch panel having a plurality of drive electrodes, a plurality of detection electrodes, and a plurality of capacitance components formed at intersections of the drive and detection electrodes;

a touch panel controller connected with the touch panel; and

a processor connected with the touch panel controller,

wherein the touch panel controller comprises

a plurality of drive terminals connected with the plurality of drive electrodes;

a drive circuit operable to output a drive pulse from the plurality of drive terminals;

a plurality of detection terminals connected with the plurality of detection electrodes;

a detection circuit operable to create detection data by accumulating signals input through each detection terminal in synchronization with change in the drive pulse; and

a control circuit operable to control the action of detecting a touch and no touch by use of the drive circuit and the detection circuit,

wherein the detection circuit has a two-edge detection mode for creating detection data by accumulating, in terms of absolute value components, signals which are input through each detection terminal in synchronization with rising and falling changes of the drive pulse respectively and alternately change in polarity, and

wherein the processor calculates, based on the detection data, a coordinate point of a position on the touch panel where the touch panel is touched.

15. The electronic device according to claim 14 , wherein the detection circuit comprises:

an integration circuit configured to integrate a signal input through each detection terminal; and

an analog-to-digital conversion circuit configured to convert an analog signal resulting from the integration by the integration circuit into a digital signal to produce the detection data,

wherein the integration circuit has an operational amplifier, an integration capacitance, and a switching circuit configured to switch the connection of the integration capacitance between an inverting input terminal of the operational amplifier and an output terminal thereof by switching the connection of the integration capacitance between the inverting input terminal of the operational amplifier and the output terminal thereof, and

wherein the control circuit switches the connection of the switching circuit immediately before rising and falling changes of the drive pulse.

16. The electronic device according to claim 15 , wherein an initial voltage of an output terminal of the integration circuit in the action of detecting a touch and no touch is a voltage close to a center value of an input range of the analog-to-digital conversion circuit.

17. The electronic device according to claim 16 ,

Wherein, when a capacitance component of the intersection has been reduced by a touch, multiple-pulse driving is performed on the drive electrodes by a drive pulse, and the driving is terminated at a falling edge of the pulse, to cause a signal voltage obtained in the integration circuit to be equal to or lower than an upper limit of the input range of the analog-to-digital conversion circuit; and

wherein, when the capacitance component of the intersection has not been reduced because of no touch, multiple-pulse driving is performed on the drive electrodes by a drive pulse, and the driving is terminated at a falling edge of the pulse, to cause a signal voltage obtained in the integration circuit to be lower than a signal voltage in the touched condition.

18. The electronic device according to claim 16 ,

Wherein when a capacitance component of the intersection has been reduced by a touch, multiple-pulse driving is performed on the drive electrodes by a drive pulse, and the driving is terminated at a rising edge of the pulse, to cause a signal voltage obtained in the integration circuit to be equal to or higher than a lower limit of the input range of the analog-to-digital conversion circuit; and

wherein, when the capacitance component of the intersection has not been reduced because of no touch, multiple-pulse driving is performed on the drive electrodes by a drive pulse, and the driving is terminated at a rising edge of the pulse, to cause a signal voltage obtained in the integration circuit to be higher than a signal voltage in the touched condition.

19. The electronic device according to claim 16 , further comprising:

a register configured to provide an instruction on which of first and second driving-termination modes should be selected,

wherein in the first driving-termination mode, driving by a drive pulse is terminated at a rising edge of the drive pulse, and in the second driving-termination mode, driving by a drive pulse is terminated at a falling edge of the drive pulse.

20. The electronic device according to claim 19 , wherein the register is provided in the control circuit and is rewritable for the processor.

21. The electronic device according to claim 16 , further comprising:

a display panel having a plurality of liquid crystal display cells disposed at intersections of the scan and signal electrodes;

a display panel controller configured to output a scan pulse and a signal voltage to scan and signal electrodes of a display panel respectively,

wherein the touch panel is an in-cell touch panel disposed in the display panel.

22. The electronic device according to claim 21 ,

wherein the control circuit controls the drive pulse in timing of change so that a timing of when the scan pulse changes and a timing of when the signal voltage changes are included in a period between rising and falling edges of the drive pulse.

23. The electronic device according to claim 22 , further comprising a separation switch configured to separate the detection circuit from the detection terminal in every predetermined period including a timing when the scan pulse changes and a timing when the signal voltage changes.

24. The electronic device according to claim 15 ,

wherein the control circuit is configured to detect a touch and no touch by

initializing an inverting input terminal of the operational amplifier and its output terminal using a first voltage supplied, as a reference voltage, to a non-inverting input terminal of the operational amplifier;

providing the drive electrode with a drive pulse with a predetermined pulse number;

switching connection of the integration capacitance with a timing immediately before an edge change of the drive pulse; and

converting, by the analog-to-digital conversion circuit, a signal subjected to integration by the integration capacitance in synchronization with each edge change of the drive pulse into a digital signal to create detection data.

25. The electronic device according to claim 14 ,

wherein the detection circuit further has a one-edge detection mode in which detection data is created by accumulating a signal input through the detection terminal more than one time in synchronization with any one of a rising change and a falling change of the drive pulse, and

wherein the semiconductor device further comprises a register configured to instruct which of the two-edge detection mode and the one-edge detection mode to select.

26. The electronic device according to claim 25 , wherein the register is a mode register provided in the control circuit, and is rewritable for the processor.