Display device
According to one embodiment, a display device includes common electrodes, detection electrodes, a common-electrode drive circuit including shift registers and switch circuits electrically connected to the shift registers, and a driver which outputs four-phase clock signals and a touch-drive signal, wherein a reset operation of the each shift register is controlled by predetermined two of the four-phase clock signals, each of the switch circuits connects a signal line from the driver to common electrodes based on a shift signal output from an associated shift register, and the each switch circuit causes the touch-drive signal from the driver to be supplied to the common electrodes of the block during a period from time at which the shift signal is output from the associated shift register to time at which a predetermined one of the four-phase clock signals is input.
1. A display device comprising:
a plurality of common electrodes extending in a first direction and arranged in parallel with each other;
a plurality of detection electrodes extending in a second direction crossing the first direction and arranged in parallel with each other;
a common-electrode drive circuit including a plurality of shift registers connected in series to each other and a plurality of switch circuits electrically connected to the shift registers, respectively; and
a driver which outputs four-phase clock signals and a touch-drive signal to control the common-electrode drive circuit,
wherein
each of the shift registers is configured to transfer a shift signal, and a reset operation of the each shift register is controlled by predetermined two of the four-phase clock signals,
each of the switch circuits connects a signal line from the driver to a common electrode or electrodes of an associated block based on a shift signal output from an associated shift register for outputting the touch-drive signal,
the each switch circuit causes the touch-drive signal from the driver to be supplied to the common electrode or electrodes of the block during a period from time at which the shift signal is output from the associated shift register to time at which a predetermined one of the four-phase clock signals is input,
each of the switch circuits supplies the touch-drive signal to the signal line when the touch-drive signal is input from the driver, and disconnects the signal line from the common electrode or electrodes of the block when the predetermined one of the four-phase clock signals is input from the driver,
the driver successively and repeatedly outputs first to fourth clock signals that are the four-phase clock signals, and
where a clock signal for controlling a transfer operation of the shift register is an Nth clock signal, a clock signal for controlling the reset operation of the shift register is an Mth clock signal, and a clock signal to be input to the switch circuit connected to the shift register is a Kth clock signal, N, M and K are integers of 4 or less, and the following relationships are satisfied:
(N+2)≡M mod 4
when M≡1 mod 4 or M≡2 mod 4, K=4, and
when M≡3 mod 4 or M≡0 mod 4, K=2.
2. The display device according to claim 1 , wherein the driver repeatedly performs an operation for outputting the touch-drive signal to the common-electrode drive circuit after successively outputting the first to third clock signals to the common-electrode drive circuit, and then outputting the touch-drive signal to the common-electrode drive circuit after successively outputting two clock signals from the fourth clock signal to the common-electrode drive circuit.
3. The display device according to claim 1 , wherein the driver repeatedly performs an operation for outputting the touch-drive signal to the common electrode circuit after successively outputting two clock signals from the first clock signal to the common-electrode circuit.
4. The display device according to claim 1 , wherein
the common electrodes are used as electrodes for a touch-drive operation and electrodes for an image display operation, and
the each switch circuit applies a common voltage for the image display operation to the common electrode or electrodes of the block, when the image display operation is performed, and supplies the touch-drive signal to the common electrode or electrodes of the block when a touch detection operation is performed.
5. The display device according to claim 4 , wherein the driver further outputs to the common-electrode drive circuit a signal for indicating whether the image display operation is performed or the touch-drive operation is performed and the common voltage.
6. A display device comprising:
common electrodes doubling as electrodes for an image display operation and electrodes for a touch detection operation; and
a drive circuit which drives the common electrodes,
wherein
the common electrodes include an nth common electrode (n≥1), an n+1th common electrode and an n+2th common electrode,
the drive circuit includes: switch circuits which output signals for the touch detection signal or signals for the image display operation to the common electrodes in a switchable manner; and shift register circuits which output control signals to the switch circuits,
the switch circuits include an nth switch circuit, an n+1th switch circuit and an n+2th switch circuit,
the nth switch circuit, the n+1th switch circuit and the n+2th switch circuit hold control signals from the shift register circuits as an nth switch signal, an n+1th switch signal and an n+2th switch signal, respectively,
the nth switch circuit, the n+1th switch circuit and the n+2th switch circuit are electrically connected to the nth common electrode, the n+1th common electrode and the n+2th common electrode, respectively, and
in a period in which the nth switch circuit and the n+1th switch circuit simultaneously hold the nth switch signal and the n+1th switch signal, respectively, the n+2th switch circuit starts to hold the n+2th switch signal,
clock signals each of which comprises a first voltage and a second voltage are input to the shift register circuits,
the clock signals include a first clock signal, a second clock signal, a third clock signal and a fourth clock signal,
the first clock signal, the second clock signal, the third clock signal and the fourth clock signal are transformed into first voltages in this order, and
the nth switch circuit, to which the first voltage obtained by transforming the first clock signal is input as a control signal, and the n+1th switch circuit to which the first voltage obtained by transforming the second clock signal is input as another control signal, stop holding of the nth switch signal and holding of the n+1th switch signal, respectively, upon reception of the first voltage from the fourth clock signal.
7. The display device according to claim 6 , wherein the switch circuits include: first output transistors which output signals for the touch detection operation; and second output transistors which output signals for the image display operation.
8. The display device according to claim 7 , wherein
a touch period signal indicating a touch detection period is input to a switch circuit, and
the switch circuit supplies the touch period signal to the first output transistor thereof to turn on the first output transistor, in accordance with the control signal from an associated shift register.
9. The display device according to claim 7 , wherein in a period in which the nth switch circuit and the n+1th switch circuit simultaneously hold the nth switch signal and the n+1th switch signal, respectively, the first output transistors of the nth switch circuit and the n+1th switch circuit are turned on.
10. The display device according to claim 7 , wherein after the n+2th switch circuit holds the n+1th switch signal, the first output transistors of the n+1th switch circuit and the n+2th switch circuit are turned on.
11. The display device according to claim 7 , wherein
a display period signal indicating a display period is input to a switch circuit, and
the switch circuit supplies the display period signal to the second output transistor thereof to turn on the second output transistor, in accordance with a control signal from an associated shift register.
12. A display device comprising:
a plurality of common electrodes doubling as electrodes for an image display operation and electrodes for a touch detection operation; and
a plurality of drive circuits for driving the common electrodes,
wherein
the drive circuits include: switch circuits each of which outputs a signal for the touch detection operation or a signal for the image display operation to the common electrodes in a switchable manner; and shift register circuits each of which outputs a control signal to an associated one of the switch circuits,
the switch circuits include hold circuits each of which holds the control signal from an associated one of the shift register circuits as a switch signal,
clock signals each of which comprises a first voltage and a second voltage are input to the shift register circuits,
the clock signals include a first clock signal, a second clock signal, a third clock signal and a fourth clock signal,
the first clock signal, the second clock signal, the third clock signal and the fourth clock signal are transformed into first voltages in this order,
the common electrodes include a first common electrode and a second common electrode which are arranged adjacent to each other,
the switch circuits include a first switch circuit which outputs a signal for the touch detection operation to the first common electrode, upon reception of the first clock signal, which is input as a control signal,
the switch circuits include a second switch circuit which outputs a signal for the touch detection operation to the second common electrode upon reception of the second clock signal, which is input as another control signal, and
hold circuits of the first switch circuit and the second switch circuit stop holding of respective switch signals with the first voltage of the fourth clock signal.
13. The display device according to claim 12 , wherein the switch circuits include: first output transistors each of which outputs a signal for the touch detection operation; and second output transistors each of which outputs a signal for the image display operation.
14. The display device according to claim 13 , wherein
a touch period signal indicating a touch detection period is input to a switch circuit, and
the switch circuit supplies the touch period signal to the first output transistor thereof to turn on the first output transistor, in accordance with the switch signal.
15. The display device according to claim 14 , wherein in a period in which the first switch circuit and the second switch circuit simultaneously hold the switch signals, first output transistors of the first switch circuit and the second switch circuit are turned on by the touch period signal.
16. The display device according to claim 14 , wherein
a third common electrode is located adjacent to the second common electrode,
a third switch circuit outputs the signal for the touch detection operation to the third common electrode, and
after the third switch circuit holds a switch signal, first output transistors of the first to third switch circuits are turned on.
17. The display device according to claim 13 ,
wherein
a display period signal indicating a display period is input to a switch circuit, and
the switch circuit supplies the display period signal to the second output transistor thereof to turn on the second output transistor, in accordance with the switch signal.