Display device and method of driving the same
View Patent ↗According to one embodiment, a pixel signal from a memory is supplied to an arbitrary pixel. A controller selectively switches a scanning frequency of common electrodes including a touch detection system, between a higher frequency and a lower frequency, and allocates banks in the memory, each bank having a capacity of a fixed number of items of the pixel data. The controller defines one unit including a group of lines of the pixel data, sets a line number of the one unit to the fixed number when the scanning frequency is the higher frequency, and sets the line number of the one unit to another line number which is greater than the fixed number when the scanning frequency is the lower frequency.
1. A display device comprising:
scan lines;
signal lines;
pixels arranged near intersections of the scan lines and the signal lines, respectively;
a memory to which pixel data is written and from which the written pixel data is read;
a pixel signal output circuit configured to output a pixel signal based on the pixel data read from the memory to arbitrary pixels through the signal lines;
driving electrodes;
a touch detection circuit configured to detect signals corresponding to capacitance change based on a scanning signal supplied to the driving electrodes; and
a controller configured to
selectively switch a scanning frequency of the scanning signal for scanning the driving electrodes between a first frequency and a second frequency which is less than the first frequency,
allocate banks in the memory, each bank having a capacity of a fixed number of items of the pixel data,
set a group of items of the pixel data to be consecutively written to the memory as one unit,
set the one unit to a first number of items of pixel data which is an integral multiple of the fixed number when the scanning frequency is the first frequency, and
set the one unit to a second number of items of pixel data which is greater than the fixed number when the scanning frequency is the second frequency.
2. The display device of claim 1 , wherein
the controller is configured to
set the one unit to the first number which is equal to the fixed number when the scanning frequency is the first frequency.
3. The display device of claim 1 , wherein
the controller is configured to set the one unit to the second number which is an integral multiple of the fixed number when the scanning frequency is the second frequency.
4. The display device of claim 1 , wherein
the controller is configured to set the first frequency to be n-times greater than the second frequency, where n is a positive integer equal to or greater than two.
5. The display device of claim 4 , wherein the controller is configured to set the one unit to the second number which is n-times greater than the fixed number when the scanning frequency is the second frequency.
6. The display device of claim 4 , wherein
a number of the banks is equal to or greater than n+1.
7. The display device of claim 1 , wherein
a number of the banks is four or three.
8. The display device of claim 1 , wherein
the touch detection circuit is configured to receive a detection signal from the driving electrodes and detect noise, and
the controller is configured to switch the frequency of the scanning signal from the first frequency to the second frequency when the touch detection circuit detects noise.
9. A display comprising:
scan lines;
signal lines;
pixels arranged near intersections of the scan lines and the signal lines, respectively;
a memory to which pixel data is written and from which the written pixel data is read;
a pixel signal output circuit configured to output a pixel signal based on the pixel data read from the memory to arbitrary pixels through the signal lines;
driving electrodes;
a touch detection circuit configured to detect signals corresponding to capacitance change based on a scanning signal supplied to the driving electrodes; and
a controller configured to
selectively switch a scanning frequency of the scanning signal for scanning the driving electrodes between a first frequency and a second frequency which is less than the first frequency,
allocate banks in the memory regardless of whether the scanning frequency is the first frequency or the second frequency, each bank having a capacity of a fixed number of items of the pixel data,
wherein the touch detection circuit is configured to receive a detection signal from the driving electrodes and detect noise, and
the controller is configured to switch the scanning frequency of the scanning signal from the second frequency to the first frequency when the touch detection circuit does not detect noise for a certain time.
10. The display device of claim 9 ,
wherein the driving electrodes are used as the common electrodes which constitute parts of the pixels.
11. The display device of claim 9 , further comprising:
a first driving circuit; and
a second driving circuit,
wherein
the first driving circuit is configured to supply a common voltage to the driving electrodes in display periods in one frame period, and
the second driving circuit is configured to supply a touch detection driving signal to the driving electrodes in a touch detection period between the display periods in the one frame period.
12. A method of driving a display device, the display device comprising signal lines; scan lines; pixels arranged near intersections of the scan lines and the signal lines, respectively; a memory to which pixel data is written and from which the written pixel data is read; a pixel signal output circuit configured to output a pixel signal based on the pixel data read from the memory to arbitrary pixels through the signal lines; and a controller, the method comprising:
selectively switching a scanning frequency of a scanning signal for scanning the driving electrodes between a first frequency and a second frequency which is less than the first frequency;
allocating banks in the memory regardless of whether the scanning frequency is the first frequency or the second frequency, each bank having a capacity of a fixed number of items of the pixel data;
setting a group of items of the pixel data to be consecutively written to the memory as one unit;
setting the one unit to a first number of items of pixel data which is an integral multiple of the fixed number when the scanning frequency is the first frequency; and
setting the one unit to a second number of items of pixel data which is greater than the fixed number when the scanning frequency is the second frequency.
13. A display device comprising:
scan lines;
signal lines;
pixels arranged near intersections of the scan lines and the signal lines, respectively;
a memory to which pixel data is written and from which the written pixel data is read;
a pixel signal output circuit configured to output a pixel signal based on the pixel data read from the memory to arbitrary pixels through the signal lines;
driving electrodes;
a touch detection circuit configured to detect signals corresponding to capacitance change based on a scanning signal supplied to the driving electrodes; and
a controller,
wherein the controller is configured to
selectively switch a scanning frequency of the scanning signal for scanning the driving electrodes between a first frequency and a second frequency which is less than the first frequency,
allocate banks in the memory, wherein each bank to which a time required for consecutively writing the pixel data is a fixed time,
set a write period of the pixel data to be consecutively written to the memory as one unit,
set the one unit to a first period which is an integral multiple of the fixed time when the scanning frequency is the first frequency, and
set the one unit to a second period which is longer than the fixed time when the scanning frequency is the second frequency.
14. The display device of claim 13 , wherein the controller is configured to
set the one unit to the first period which is equal to the fixed time when the scanning frequency is the first frequency.
15. The display device of claim 13 , wherein the controller is configured to
set the one unit to the second number of items of pixel data which is an integral multiple of the fixed number when the scanning frequency is the second frequency.
16. The display device of claim 13 ,
wherein the driving electrodes are used as common electrodes which constitute parts of the pixels.
17. The display device of claim 13 , further comprising:
a first driving circuit; and
a second driving circuit,
wherein
the first driving circuit supplies a common voltage to the driving electrodes in display periods in one frame period, and
the second driving circuit supplies a touch detection driving signal to the driving electrodes in a touch detection period between the display periods in the one frame period.