Liquid crystal display panel, common inversion driving method, liquid crystal display device, and liquid crystal display driver
View Patent ↗A driving method for driving an LCD panel having a counter electrode and a source line. In a first period, the counter electrode is driven to a potential VCOMH. In a second period, the counter electrode and the source line are short-circuited to a power supply interconnection having a power supply potential VCI. In a third period, the counter electrode is connected to a ground interconnection while the source line is kept to be short-circuited to the power supply interconnection. In a fourth period, the counter electrode is pulled down to a potential VCOML lower than a ground potential In a fifth period, the source line is driven to a potential corresponding to an image data while the counter electrode is kept to the potential VCOML. The electric power consumed in pulling down the counter electrode from a positive potential to a negative potential can be effectively reduced.
1. A driving method of a liquid crystal display panel having a source line and a counter electrode, said driving method comprising:
driving the counter electrode to a first potential being a high level of an amplitude of a potential of the counter electrode;
setting the counter electrode and the source line to a second potential by short-circuiting the counter electrode and the source line to a power supply interconnection having the second potential lower than the first potential, after the driving;
connecting the counter electrode to a ground interconnection having a ground potential while the source line is kept to be short-circuited to the power supply interconnection, after the setting;
driving the counter electrode to a third potential being a low level of an amplitude of a potential of the counter electrode, after the connecting; and
driving the source line to a potential corresponding to an image data, after the connecting,
wherein the setting of the counter electrode and the source line to the second potential occurs in a period of one frame.
2. The driving method according to claim 1 , wherein the driving the source line is performed after the driving the counter electrode to the third potential,
wherein, in the driving the source line, the source line is driven to the potential corresponding to the image data while the counter electrode is kept to the third potential, and
wherein, in the driving the counter electrode to the third potential, the source line is set to a high impedance state.
3. The driving method according to claim 1 , wherein the driving the source line is performed after the driving the counter electrode to the third potential,
wherein, in the driving the source line, the source line is driven to the potential corresponding to the image data while the counter electrode is kept to the third potential, and
wherein, in the driving the counter electrode to the third potential, the source line is kept to be short-circuited to the power supply interconnection.
4. The driving method according to claim 1 , wherein the driving the source line is performed after the driving the counter electrode t o the third potential,
wherein, in the driving the source line, the source line is driven to the potential corresponding to the image data while the counter electrode is kept to the third potential, and
wherein, in the driving the counter electrode to the third potential, the source line is set to a high impedance state or is kept to be short-circuited to the power supply interconnection, in response to the image data.
5. The driving method according to claim 1 , wherein the driving the counter electrode to the third potential and the driving the source line to the potential corresponding to the image data are simultaneously performed.
6. The driving method according to claim 1 , wherein the source line is connected to an output of a source driver circuit for driving the source line,
wherein the counter electrode is driven by an output of a VCOM circuit for driving the counter electrode, and
wherein, in the setting, the counter electrode and the source line are short-circuited to each other via a switch connected between the output of the source driver circuit and the output of the VCOM circuit.
7. The driving method according to claim 1 , wherein the driving the source line to the potential corresponding to the image data is performed by a driving circuit operated based on:
a boosted-up power supply voltage generated by boosting-up a first power supply voltage supplied by the power supply interconnection; or
a second power supply voltage generated by a regulator circuit from the boosted-up power supply voltage.
8. A liquid crystal display device comprising:
a liquid crystal display panel having a source line and a counter electrode; and
an LCD driver which comprises:
a source driver circuit having a source output connected to the source line;
a VCOM circuit having a VCOM output connected to the counter electrode and a power supply interconnection having a predetermined potential,
wherein the source driver circuit comprises:
a driving section configured to drive the source line; and
a first switch connected between the source output and the power supply interconnection,
wherein the VCOM circuit comprises:
other than the driving section and the first switch of the source driver circuit;
a first driving section configured to drive the counter electrode to a first potential being a high level of an amplitude of a potential of the counter electrode;
a second switch connected between the counter electrode and the power supply interconnection;
a third switch connected between the counter electrode and a ground interconnection; and
a second driving section configured to drive the counter electrode to a third potential being a low level of an amplitude of a potential of the counter electrode,
wherein the predetermined potential of the power supply interconnection is lower than the first potential and higher than the ground interconnection, and
wherein the source driver circuit is configured to short-circuit the source line to the power supply interconnection in a period of one frame, and
wherein the VCOM circuit is configured to short-circuit the counter electrode to the power supply interconnection in a same period of one frame as the short-circuiting of the source line to the power supply interconnection.
9. The liquid crystal display device according to claim 8 , wherein, in a first period, the first driving section of the VCOM circuit drives the counter electrode to the first potential,
wherein, in a second period after the first period, the source driver circuit short-circuits the source line to the power supply interconnection by turning on the first switch, and the VCOM circuit short-circuits the counter electrode to the power supply interconnection by turning on the second switch,
wherein, in a third period after the second period, the source driver circuit keeps the source line to be short-circuited to the power supply interconnection, and the VCOM circuit connects the ground interconnection to the counter electrode by turning on the third switch, and
wherein, after the third period, the second driving section of the VCOM circuit pulls down the counter electrode to the third potential, and the source driver circuit drives the source line to a potential corresponding to an image data.
10. The liquid crystal display device according to claim 9 , wherein, in a fourth period after the third period, the second driving section of the VCOM circuit pulls down the counter electrode to the third potential, and
wherein, in a fifth period after the fourth period, the VCOM circuit keeps the counter electrode to the third potential, and the source driver circuit drives the source line to the potential corresponding to the image data.
11. The liquid crystal display device according to claim 9 , wherein, in a fourth period after the third period, the second driving section of the VCOM circuit drives the counter electrode to the third potential, and at the same time, the source driver circuit drives the source line to the potential corresponding to the image data.
12. The liquid crystal display device according to claim 8 , wherein the LCD driver further comprises:
a power supply circuit configured to generate a second power supply voltage from a first power supply voltage supplied from the power supply interconnection, and supplies the second power supply voltage to the source driver circuit,
wherein the power supply circuit generates a boosted-up power supply voltage by boosting up the first power supply voltage, and supplies the boosted-up power supply voltage itself or a voltage generated by a regulator circuit from the boosted-up power supply voltage to the source driver circuit as the second power supply voltage.
13. The liquid crystal display device according to claim 8 , wherein the source driver circuit further comprises:
a common interconnection connected to the source output via the first switch; and
a fourth switch connected between the common interconnection and the power supply interconnection, and
wherein the second switch is connected between the VCOM output of the VCOM circuit and the common interconnection.
14. The liquid crystal display device according to claim 13 , wherein the source driver circuit further comprises:
a fifth switch connected to the VCOM output in parallel with the second switch and connected between the VCOM output and the power supply interconnection.
15. The liquid crystal display device according to claim 13 , wherein the source driver circuit further comprises:
a sixth switch connected between the common interconnection and a ground interconnection.
16. An LCD driver for driving a liquid crystal display panel having a source line and a counter electrode, the LCD driver comprising:
a source driver circuit having a source output connected to the source line;
a VCOM circuit having a VCOM output connected to the counter electrode; and
a power supply interconnection having a predetermined potential,
wherein the source driver circuit comprises:
a driving section configured to drive the source line; and
a first switch connected between the source output and the power supply interconnection,
wherein the VCOM circuit comprises:
other than the driving section and the first switch of the source driver circuit;
a first driving section configured to drive the counter electrode to a first potential being a high level of an amplitude of a potential of the counter electrode;
a second switch connected between the counter electrode and the power supply interconnection;
a third switch connected between the counter electrode and a ground interconnection; and
a second driving section configured to drive the counter electrode to a third potential being a low level of an amplitude of a potential of the counter electrode, and
wherein the predetermined potential of the power supply interconnection is lower than the first potential and higher than the ground interconnection, and
wherein the source driver circuit is configured to short-circuit the source line to the power supply interconnection in a period of one frame, and
wherein the VCOM circuit is configured to short-circuit the counter electrode to the power supply interconnection in a same period of one frame as the short-circuiting of the source line to the power supply interconnection.
17. The LCD driver according to claim 16 , further comprising:
a power supply circuit configured to generate a second power supply voltage from a first power supply voltage supplied from the power supply interconnection, and supplies the second power supply voltage to the source driver circuit, and
wherein the power supply circuit generates a boosted-up power supply voltage by boosting up the first power supply voltage, and supplies the boosted-up power supply voltage itself or a voltage generated by a regulator circuit from the boosted-up power supply voltage to the source driver circuit as the second power supply voltage.
18. The LCD driver according to claim 16 , wherein the source driver circuit further comprises:
a common interconnection connected to the source output via the first switch; and
a fourth switch connected between the common interconnection and the power supply interconnection, and
wherein the second switch is connected between the VCOM output of the VCOM circuit and the common interconnection.
19. The LCD driver according to claim 18 , wherein the source driver circuit further comprises:
a fifth switch connected to the VCOM output in parallel with the second switch and connected between the VCOM output and the power supply interconnection.
20. The LCD driver according to claim 18 , wherein the source driver circuit further comprises:
a sixth switch connected between the common interconnection and a ground interconnection.