Liquid crystal display controller
View Patent ↗The present invention provides a liquid crystal display controller device and method which provides for a full and/or partial display with good display quality and/or low power consumption based on the scanning period for an active scan line being dependent upon a number of reference clock pulses. Some embodiments of the present invention include one or more of the following features: keeping the frequency substantially constant for different numbers of active scan lines, allowing change of the frequency due to characteristics of the LCD, displaying gradation with near linear effective voltage characteristics, displaying graduation data with lower power, or displaying a partial or full screen in a mobile device, for example, a cell phone.
1. A display controller on one large scale integrated circuit (LSI) and capable of adjusting a frame frequency for a display panel to be coupled thereto, the display controller comprising:
an interface which receives display data from an external device to be coupled to the display controller;
a memory which stores the display data;
a register capable of setting from the external device a division ratio of a first clock signal, a number of reference clocks of a second clock signal per a scanning period, and a number of lines of the display panel;
a signal generator which divides the first clock signal by the division ratio to generate the second clock signal, and which generates a signal having the frame frequency based on the number of the second clock signal per the scanning period and the number of lines of the display panel stored in the register;
a voltage generator which generates a plurality of driving voltage signals; and
a data line driver which converts the display data into ones of the plurality of driving voltage signals to be provided to the display panel;
wherein the frame frequency is adjustable by changing the division rate and/or the number of reference clocks of the second clock signal per said scanning period in the register from the external device without changing the number of lines of the display panel in the register.
2. The display controller according to claim 1 , further comprising:
a clock generator which generates the first clock signal using an oscillator.
3. The display control device according to claim 1 ,
wherein the signal generator generates a signal synchronized with the scanning period based on the number of reference clocks of the second clock signal per the scanning period, and
wherein the display control device further comprises a scanning line driver which provides a selecting voltage and a non-selecting voltage for scanning the lines on the display panel according to the scanning period.
4. The display controller according to claim 1 , wherein the display controller has a first mode and a second mode, the frame frequency of the first mode being higher than that of the second mode.
5. The display controller according to claim 4 , wherein the first mode is a contrast-oriented mode and the second mode is a power saving mode.
6. A liquid crystal display controller comprising:
a clock generator which generates a first clock signal;
a control register capable of setting from an external device a division ratio of the first clock signal, a number of reference clocks of a second clock signal per a scanning period and a number of lines of a liquid crystal display panel; and
a signal generator which generates the second clock signal by dividing the first clock signal using the division ratio, and which generates a frame pulse having the frame frequency based on the number of reference clocks of the second clock signal per the scanning period and the number of lines of the display panel stored in the register,
wherein the frame frequency is adjustable by changing the division rate and/or the number of reference clocks of the second clock signal per a scanning period in the register from the external device without changing the number of lines of the display panel in the control register.
7. The liquid crystal display control device according to claim 6 ,
wherein the signal generator generates a signal synchronized with the scanning period based on the number of reference clocks of the second clock signal per the scanning period.
8. The liquid crystal display controller according to claim 6 , wherein the display controller has a first mode and a second mode, and,
wherein the frame frequency of the first mode is higher than that of the second mode.
9. The liquid crystal display controller according to claim 8 , wherein the first mode is a contrast-oriented mode and the second mode is a power saving mode.
10. The liquid crystal display controller according to claim 9 , wherein the liquid crystal display controller is on one LSI.
11. A display controller having a first mode and a second mode, the liquid crystal display controller comprising:
a clock generator which generates a first clock signal;
a control register capable of setting from an external device a division ratio of the first clock signal, a number of reference clocks of the second clock signal per a scanning period and a number of lines of a display panel; and
a signal generator which generates the second clock signal by dividing the first clock signal using the division ratio, and which generates a frame pulse having the frame frequency based on the number of reference clocks of the second clock signal per the scanning period and the number of lines of the display panel stored in the register,
wherein the division rate and/or the number of reference clocks of the second clock signal per a scanning period in the control register is changed from the external device without changing the number of lines of the display panel in the control register so that the frame frequency in the first mode is higher than the frame frequency in the second mode.
12. The display control device according to the claim 11 , wherein the signal generator further generates a signal synchronized with the scanning period based on the number of reference clocks of the second clock signal per the scanning period.
13. The display controller according to claim 11 , wherein the first mode is a contrast-oriented mode and the second mode is a power saving mode.
14. The display controller according to claim 9 , wherein the liquid crystal display controller is on one LSI.