Display device, control device, and control method
View Patent ↗A display device according to the present disclosure includes a panel unit including common electrodes for common use in image display and touch detection, a drive circuit configured to output a touch drive signal to each of the common electrodes, and a touch detection circuit configured to detect touch of an object onto the panel unit based on a detection signal received from each of the common electrodes. In a unit frame period, display periods and touch detection periods each including first and second sections are alternately placed. In the touch drive signal in each touch detection period, amplitude values of pulses included in the first section change from a first value to a second value larger than the first value, across the first section, and amplitude values of pulses included in the second section change from the second value to the first value across the second section.
1. A display device comprising:
a panel unit including a plurality of common electrodes for common use in image display and touch detection;
a drive circuit configured to output a touch drive signal to each of the plurality of common electrodes; and
a touch detection circuit configured to detect touch of an object onto the panel unit based on a detection signal received from each of the plurality of common electrodes, wherein
in a unit frame period, display periods and touch detection periods are alternately placed, the panel unit being caused to display an image in the display periods,
the drive circuit is configured to, in each of the touch detection periods, output the touch drive signal to each of the common electrodes,
each of the touch detection periods includes a first section and a second section, and
in the touch drive signal in each of the touch detection periods,
amplitude values of a plurality of pulses included in the first section change from a first value to a second value larger than the first value, across the first section, and
amplitude values of a plurality of pulses included in the second section change from the second value to the first value across the second section.
2. The display device according to claim 1 , wherein
the touch drive signal in each of the touch detection periods includes N pulses,
the first section includes a section from a top pulse to an Mth pulse of the touch drive signal, wherein an amplitude value of the top pulse is the first value and an amplitude value of the Mth pulse is the second value, and
the second section includes a section from an (N−(M−1))th pulse to a last pulse of the touch drive signal, wherein an amplitude value of the (N−(M−1))th pulse is the second value and an amplitude value of the last pulse is the first value, wherein M is an integer of 2 or more and N is an integer of (2M−1) or more.
3. The display device according to claim 2 , wherein in the touch drive signal in each of the touch detection periods, an amplitude value of each pulse from the Mth pulse to the (N−(M−1))th pulse is the second value.
4. The display device according to claim 2 , wherein in the touch drive signal in each of the touch detection periods, in a section from the Mth pulse to the (N−(M−1))th pulse, amplitude values of these pulses change from the second value to a third value larger than the first value and smaller than the second value, and change from the third value to the second value.
5. The display device according to claim 1 , wherein the drive circuit is configured to:
control the amplitude values of the pulses in the first section from the first value to the second value in stages, and
control the amplitude values of the pulses in the second section from the second value to the first value in stages.
6. The display device according to claim 1 , wherein the drive circuit is further configured to:
generate a signal including a plurality of pulses;
generate a window function signal based on a window function; and
multiply the signal by the window function signal to generate the touch drive signal.
7. The display device according to claim 6 , wherein the window function w(t) is represented by Expression (1) below:
W
(
t
)
=
D
A
∑
n
=
1
k
(
2
π
)
×
sin
(
n
π
×
D
)
n
×
cos
(
2
π
n
ft
)
(
1
)
wherein t is time, D is a duty ratio, A is an amplitude, k is an order of a waveform included in the window function, and f is a touch detection occurrence frequency.
8. The display device according to claim 1 , wherein the drive circuit is configured to generate the touch drive signal based on data indicating a signal waveform of the touch drive signal.
9. The display device according to claim 1 , wherein the drive circuit is configured to:
have a first mode and a second mode as operating modes for the touch detection periods;
output, in the second mode, the touch drive signal to each of the plurality of common electrodes in each of the touch detection periods; and
output, in the first mode, a signal including a plurality of pulses having a constant amplitude to each of the plurality of common electrodes in each of the touch detection periods.
10. The display device according to claim 9 , wherein the first mode is a normal operating mode and the second mode is an operating mode to suppress noise.
11. The display device according to claim 10 , further comprising a controller configured to determine an operating mode of the drive circuit, wherein
the controller is configured to acquire a report about a reception signal from a device to which the display device is connected, and determine the operating mode to be one of the first mode and the second mode based on the report.
12. The display device according to claim 10 , further comprising a controller configured to determine an operating mode of the drive circuit, wherein
the controller is configured to determine the operating mode to be the second mode when a specific frequency has been acquired, and determine the operating mode to be the first mode when the specific frequency has not been acquired.
13. The display device according to claim 1 , wherein each pulse included in the touch drive signal in each of the touch detection periods includes a sinusoidal signal, a rectangular wavy signal, a step wavy signal, or a triangular wavy signal.
14. The display device according to claim 1 , wherein
the pulses included in the touch drive signal in each of the touch detection periods are a sinusoidal signal,
the display device further comprises a controller configured to change a touch drive frequency which is a frequency of the touch drive signal, and
the controller is configured to determine the touch drive frequency F after change, so as to satisfy Expression (2) below:
F
=
N
P
T
b
(
2
)
wherein Np is a number of pulses and Tb is a touch detection period.
15. A display device comprising:
a panel unit including a plurality of common electrodes for common use in image display and touch detection;
a drive circuit configured to output a touch drive signal to each of the plurality of common electrodes;
a touch detection circuit configured to detect touch of an object onto the panel unit based on a detection signal received from each of the plurality of common electrodes; and
a controller configured to change a touch drive frequency which is a frequency of the touch drive signal, wherein
in a unit frame period, display periods and touch detection periods are alternately placed, the panel unit being caused to display an image in the display periods,
pulses included in the touch drive signal in each of the touch detection periods are a sinusoidal signal, and
the controller is configured to determine the touch drive frequency F after change, so as to satisfy Expression (2) below:
F
=
N
P
T
b
(
2
)
wherein Np is a number of pulses and Tb is a touch detection period.
16. A control method of controlling a panel unit including a plurality of common electrodes for common use in image display and touch detection, the method comprising:
outputting a touch drive signal to each of the plurality of common electrodes; and
detecting touch of an object onto the panel unit based on a detection signal received from each of the plurality of common electrodes, wherein
in a unit frame period, display periods and touch detection periods are alternately placed, the panel unit being caused to display an image in the display periods,
the touch drive signal is output to each of the plurality of common electrodes in each of the touch detection periods,
each of the touch detection periods includes a first section and a second section, and
in the touch drive signal in each of the touch detection periods,
amplitude values of a plurality of pulses included in the first section change from a first value to a second value larger than the first value, across the first section, and
amplitude values of a plurality of pulses included in the second section change from the second value to the first value across the second section.