Display system
A touch detection circuit performs detection of a touch by an object to a display device, based on a touch detection signal received from each of multiple common electrodes of the display device. One of a set of first and second common electrodes and a set of first and third common electrodes is arranged in the same column, and the other is arranged in the same row. At least one of the sets are adjacent to each other. First and second A/D conversion circuits perform A/D conversion on a signal supplied to a first input node and a signal supplied to a second input node, respectively. First, second, and third switches switch between conduction and non-conduction between the first common electrode and the first input node, between the second common electrode and the second input node, and between the third common electrode and the first input node, respectively.
1. A display system comprising:
a display device that includes a plurality of common electrodes arranged in a matrix and shared for image display and touch detection; and
a control device that controls the display device, wherein
the control device includes a touch detection circuit that performs detection of a presence or absence of a touch made by an object to the display device, based on a touch detection signal received from each of the plurality of common electrodes,
the touch detection circuit includes:
a first A/D conversion circuit that performs A/D conversion on a signal supplied to a first input node; and
a second A/D conversion circuit that performs A/D conversion on a signal supplied to a second input node, and that detects the presence or absence of a touch based on a signal A/D converted by the first A/D conversion circuit and a signal A/D converted by the second A/D conversion circuit,
the plurality of common electrodes include a first common electrode, a second common electrode, and a third common electrode,
one of a set of the first common electrode and the second common electrode and an other set of the first common electrode and the third common electrode is arranged in a same column, the other set is arranged in a same row, and the electrodes in at least one of the set of the first common electrode and the second common electrode and the other set of the first common electrode and the third common electrode are adjacent to each other,
the display device includes:
a first signal line that is connected to the first common electrode;
a second signal line that is connected to the second common electrode; and
a third signal line that is connected to the third common electrode, and the control device includes:
a first switch that is connected between the first signal line and the first input node and that switches between conduction and non-conduction between the first common electrode and the first input node;
a second switch that is connected between the second signal line and the second input node and that switches between conduction and non-conduction between the second common electrode and the second input node;
a third switch that is connected between the third signal line and the first input node and that switches between conduction and non-conduction between the third common electrode and the first input node;
a first control signal line that is directly connected to the first switch and the second switch and that switches on and off of the first switch and on and off of the second switch; and
a second control signal line that is connected to the third switch and that switches on and off of the third switch.
2. The display system according to claim 1 , wherein
the first common electrode and the second common electrode are adjacent to each other, and the first common electrode and the third common electrode are adjacent to each other.
3. The display system according to claim 1 , wherein
the first common electrode and the second common electrode are located in the same row, and
the first common electrode and the third common electrode are located in the same column.
4. The display system according to claim 1 , wherein
the first common electrode and the second common electrode are located in the same column, and
the first common electrode and the third common electrode are located in the same row.
5. The display system according to claim 1 , wherein
the plurality of common electrodes include a fourth common electrode arranged in the same row or the same column as that for the first common electrode and the third common electrode,
the first common electrode, the third common electrode, and the fourth common electrode are located within a range that allows for detecting that there has been the touch when the object touches the third common electrode, and
the display device further includes:
a fourth signal line that is connected to the fourth common electrode;
a fourth switch that is connected between the fourth signal line and the first input node and that switches between conduction and non-conduction between the fourth common electrode and the first input node; and
a third control signal line that is connected to the fourth switch and that switches on and off of the fourth switch.
6. The display system according to claim 5 , wherein
a frame period in the display device includes three or more display periods for which the display device displays an image and three or more touch detection periods for which the touch detection circuit performs the touch detection, and the display periods and the touch detection periods are alternately arranged within the frame period,
the three or more touch detection periods include a first touch detection period and a second touch detection period, and
the touch detection circuit detects the presence or absence of the touch at the first common electrode during the first touch detection period, detects the presence or absence of the touch at the fourth common electrode during the second touch detection period, and does not detect the presence or absence of the touch at the third common electrode in any of the touch detection periods during the frame period.
7. The display system according to claim 6 , wherein
the second touch detection period follows the first touch detection period.
8. The display system according to claim 7 , wherein
the three or more touch detection periods further include a third touch detection period after the second touch detection period, and
the touch detection circuit detects the presence or absence of the touch at the first common electrode in the third touch detection period.
9. The display system according to claim 5 , wherein
a frame period in the display device includes three or more display periods for which the display device displays an image and three or more touch detection periods for which the touch detection circuit detects the presence or absence of the touch, and the display periods and the touch detection periods are alternately arranged within the frame period,
the touch detection circuit operates by switching between operation in a first mode and operation in a second mode,
in the first mode, the touch detection circuit detects the presence or absence of the touch at the first common electrode, the third common electrode, and the fourth common electrode in a single frame period, and
in the second mode, the touch detection circuit detects the touch at the first common electrode and the fourth common electrode and does not detect the touch at the third common electrode in the single frame period.
10. The display system according to claim 9 , wherein
the touch detection circuit switches the operation in the second mode to the operation in the first mode when the touch is detected at the least one of the first common electrode and the fourth common electrode in the second mode.
11. The display system according to claim 5 , wherein
the touch detection circuit further includes:
a memory in which a program is stored; and
a processor coupled to the memory and configured to perform processing by executing the program, the processing including:
deriving a first detection value representing a difference value between a capacitance of the first common electrode and a reference capacitance based on the touch detection signal received from the first common electrode, and deriving a third detection value representing a difference value between a capacitance of the fourth common electrode and the reference capacitance based on the touch detection signal received from the fourth common electrode;
interpolating a second detection value for the third common electrode based on the first detection value and the third detection value when touch detection has not been performed at the third common electrode; and
deriving a touch position based on the first detection value, the second detection value, and the third detection value.
12. The display system according to claim 1 , wherein
the touch detection circuit is located on an upper or lower side of the plurality of common electrodes in a plane view.
13. The display system according to claim 1 , wherein
the touch detection circuit is located on a left or right side of the plurality of common electrodes in a plane view.
14. A display system comprising:
a display device that includes a plurality of common electrodes arranged in a matrix and shared for image display and touch detection; and
a control device that controls the display device, wherein
the control device includes a touch detection circuit that performs detection of a presence or absence of a touch made by an object to the display device, based on a touch detection signal received from each of the plurality of common electrodes,
the touch detection circuit includes:
a first A/D conversion circuit that performs A/D conversion on a signal supplied to a first input node, and detects a touch based on a signal A/D converted by the first A/D conversion circuit,
the plurality of common electrodes include a first common electrode, a second common electrode, and a third common electrode,
one of a set of the first common electrode and the second common electrode and an other set of the second common electrode and the third common electrode is arranged in a same column, the other set is arranged in a same row, the first common electrode and the second common electrode are adjacent to each other, and the other set of second common electrode and the third common electrode are adjacent to each other,
the display device includes:
a first signal line that is connected to the first common electrode;
a second signal line that is connected to the second common electrode; and
a third signal line that is connected to the third common electrode, and
the control device includes:
a first switch that is connected between the first signal line and the first input node and that switches between conduction and non-conduction between the first common electrode and the first input node;
a second switch that is connected between the second signal line and the first input node and that switches between conduction and non-conduction between the second common electrode and the first input node;
a third switch that is connected between the third signal line and the first input node and that switches between conduction and non-conduction between the third common electrode and the first input node;
a first control signal line that is connected to the first switch and switches on and off of the first switch;
a second control signal line that is connected to the second switch and switches on and off of the second switch;
a third control signal line that is connected to the third switch and switches on and off of the third switch; and
the first A/D conversion circuit performs A/D conversion on a signal supplied from the first common electrode, the second common electrode, and the third common electrode.
15. The display system according to claim 14 , wherein
a frame period in the display device includes three or more display periods for which the display device displays an image and three or more touch detection periods for which the touch detection circuit performs the touch detection, and the display periods and the touch detection periods are alternately arranged within the frame period,
the three or more touch detection periods include a first touch detection period and a second touch detection period,
the touch detection circuit detects the presence or absence of the touch at the first common electrode during the first touch detection period, detects the presence or absence of the touch at the third common electrode during the second touch detection period, and does not detect the presence or absence of the touch at the second common electrode in any of the touch detection periods during the frame period.
16. The display system according to claim 15 , wherein
the second touch detection period is follows the first touch detection period.
17. The display system according to claim 16 , wherein
the three or more touch detection periods further include a third touch detection period after the second touch detection period, and
the touch detection circuit detects the presence or absence of the touch at the first common electrode in the third touch detection period.
18. The display system according to claim 14 , wherein
a frame period in the display device includes three or more display periods for which the display device displays an image and three or more touch detection periods for which the touch detection circuit detects the presence or absence of the touch, and the display periods and the touch detection periods are alternately arranged within the frame period,
the touch detection circuit operates by switching between operation in a first mode and operation in a second mode,
in the first mode, the touch detection circuit detects the presence or absence of the touch at the first common electrode, the second common electrode, and the third common electrode in a single frame period, and
in the second mode, the touch detection circuit detects the touch at the first common electrode and the third common electrode and does not detect the touch at the second common electrode in the single frame period.
19. The display system according to claim 18 , wherein
the touch detection circuit switches the operation in the second mode to the operation in the first mode when the touch is detected at the least one of the first common electrode and the third common electrode in the second mode.
20. The display system according to claim 14 , wherein
the touch detection circuit further includes:
a memory in which a program is stored; and
a processor coupled to the memory and configured to perform processing by executing the program, the processing including:
deriving a first detection value representing a difference value between a capacitance of the first common electrode and reference capacitance based on the touch detection signal received from the first common electrode, and deriving a third detection value representing a difference value between a capacitance of the third common electrode and the reference capacitance based on the touch detection signal received from the third common electrode;
interpolating a second detection value for the second common electrode based on the first detection value and the third detection value when touch detection has not been performed at the second common electrode; and
deriving a touch position based on the first detection value, the second detection value, and the third detection value.
21. A display system comprising:
a display device that includes a plurality of common electrodes arranged in a matrix and shared for image display and touch detection; and
a control device that controls the display device, wherein
the control device includes a touch detection circuit that performs detection of a presence or absence of a touch made by an object to the display device, based on a touch detection signal received from each of the plurality of common electrodes,
the touch detection circuit includes:
a first A/D conversion circuit that performs A/D conversion on a signal supplied to a first input node; and
a second A/D conversion circuit that performs A/D conversion on a signal supplied to a second input node, and that detects the presence or absence of a touch based on a signal A/D converted by the first A/D conversion circuit and a signal A/D converted by the second A/D conversion circuit,
the plurality of common electrodes include a first common electrode, a second common electrode, a third common electrode, and a fourth common electrode,
one of a set of the first common electrode and the second common electrode and an other set of the first common electrode and the third common electrode is arranged in a same column, the other set is arranged in a same row, and the electrodes in at least one of the set of the first common electrode and the second common electrode and the other set of the first common electrode and the third common electrode are adjacent to each other,
the fourth common electrode is arranged in the same row or the same column as that for the first common electrode and the third common electrode,
the first common electrode, the third common electrode, and the fourth common electrode are located within a range that allows for detecting that there has been a touch when the object touches the third common electrode,
the display device includes:
a first signal line that is connected to the first common electrode;
a second signal line that is connected to the second common electrode; and a third signal line that is connected to the third common electrode; and
a fourth signal line that is connected to the fourth common electrode; and
the control device includes:
a first switch that is connected between the first signal line and the first input node and that switches between conduction and non-conduction between the first common electrode and the first input node;
a second switch that is connected between the second signal line and the second input node and that switches between conduction and non-conduction between the second common electrode and the second input node;
a third switch that is connected between the third signal line and the first input node and that switches between conduction and non-conduction between the third common electrode and the first input node;
a fourth switch that is connected between the fourth signal line and the first input node and that switches between conduction and non-conduction between the fourth common electrode and the first input node;
a first control signal line that is directly connected to the first switch and the second switch and that switches on and off of the first switch and on and off of the second switch;
a second control signal line that is connected to the third switch and that switches on and off of the third switch; and
a third control signal line that is connected to the fourth switch and switches on and off of the fourth switch;
a frame period in the display device has three or more display periods for which the display device displays an image and three or more touch detection periods for which the touch detection circuit performs touch detection, and the display periods and the touch detection periods are alternately arranged within the frame period,
the three or more touch detection periods have a first touch detection period, a second touch detection period, and a third touch detection period,
the three or more display periods have a first display period, a second display period, and a third display period,
the frame period has the first display period, the first touch detection period, the second display period, the second touch detection period, the third display period and the third touch detection period in order, and
the touch detection circuit detects the presence or absence of a touch at the first common electrode during the first touch detection period and the third touch detection period, detects the presence or absence of the touch at the fourth common electrode during the second touch detection period, and does not detect the presence or absence of the touch at the third common electrode in any of the first touch detection period, the second touch detection period and the third touch detection period.