Pixel circuits and methods for driving pixels

1. A display driver, comprising:

a digital to analog converter configured to produce a current at a selected level, an output of the digital to analog converter being coupleable to a data line of a display;

a voltage source being coupleable to the data line and configured to precharge the data line; and

a memory configured to store a level of the voltage applied to a pixel coupled to the data line in a previous frame period, wherein the voltage source is further configured to precharge the data line to a derivative of the stored voltage level prior to or during a subsequent frame period relative to the previous frame period.

2. A display driver as recited in claim 1 , wherein the digital to analog converter comprises an array of switches coupled to outputs of a demultiplexer, wherein a cumulative output of the switches on the data line varies based on which switches are conducting.

3. A display driver as recited in claim 1 , wherein the voltage source includes a voltage regulation feedback loop.

4. A display driver as recited in claim 1 , wherein the data line is precharged to below a voltage level corresponding to a black level of the pixels.

5. A display driver as recited in claim 1 , wherein the data line is precharged to above a voltage level corresponding to a black level of the pixels.

6. A display driver as recited in claim 1 , wherein the data line is precharged to about a voltage needed to supply a current to at least one pixel coupled to the data line prior to the current from the digital to analog converter being applied to the data line.

7. A display driver as recited in claim 1 , wherein, for a given pixel, the data line is precharged to about a voltage applied to that pixel in a previous frame period.

8. A display driver as recited in claim 1 , further comprising a second voltage source being coupleable to the data line.

9. For a plurality of pixels of a display, a method for precharging a data line of the display, the method comprising:

for each pixel, determining a voltage level on the data line coupled to the pixel during a previous frame period;

storing the voltage level; and

prior to or during a subsequent frame period relative to the previous frame period, precharging the data line voltage to a derivative of the stored voltage level.

10. A method as recited in claim 9 , further comprising adjusting the data line precharge voltage level based on a brightness level difference between brightness-level data of a previous frame and brightness-level data of a current frame of at least one pixel of the current frame.

11. A method as recited in claim 10 , further comprising storing the brightness-level data of the previous frame.

12. A method as recited in claim 9 , wherein the data line is precharged to about a same level as the stored voltage level, and further comprising after the precharging, applying a current to the data line to program pixels coupled to the data line.

13. A method as recited in claim 9 , wherein the data line is precharged to slightly less than the stored voltage level, and further comprising after the precharging, applying a current to the data line to program pixels coupled to the data line.

14. A method as recited in claim 9 , wherein the method is performed for each pixel in the display.

15. A method for precharging a data line of a light emitting current-driven display, comprising:

using display data derived from a previous frame for precharging each data line in the light emitting current-driven display to a voltage level corresponding to a brightness level that is less than a brightness level required at a selected pixel coupled to the data line during a next frame interval.

16. A method as recited in claim 15 , wherein each data line in the light emitting current-driven display is driven to a voltage level corresponding to a brightness level that is slightly less than a black level associated with pixels of the display.

17. A method as recited in claim 15 , wherein the precharge voltage for each pixel is calculated by storing in a frame store memory brightness-level data during the previous frame period; and adjusting the precharge voltage for any brightness level differences at each pixel between brightness-level data provided during a last frame interval and brightness-level data provided during a current frame interval based on a look-up table.

18. A method as recited in claim 15 , wherein the brightness level is slightly less than the brightness level required at the selected pixel.