Methods and apparatus for driving electro-optic displays

• US 9,530,363 B2
• Filed: 02/23/2016
• Issued: 12/27/2016
• Est. Priority Date: 11/20/2001
• Status: Expired due to Term

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated
• Inventors: Ben-Dov, Yuval, Amundson, Karl Raymond
• Primary Examiner(s): Sherman, Stephen
• Application Number:
  US15/050,997
• Publication Number:
  US 20160171935A1
• Time in Patent Office: 308 Days
• Field of Search: 345/101, 345/107, 345/204, 345208-210, 359/296
• US Class Current: 1/1
• CPC Class Codes: G02F 1/13306 Circuit arrangements or driving methods for the control of single liquid crystal cells G02F1/132, G02F1/133382 take precedence
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2310/068 Application of pulses of alternating polarity prior to the drive pulse in electrophoretic displays
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/344 based on particles moving in a fluid or in a gas, e.g. electrophoretic devices electrophoretic devices per se G02F1/167

Abstract

The performance of an electro-optic display, for example, a bistable electro-optic display, can be improved by modifying the frame rate of a base waveform used to drive a transition between gray states. Such modifications permit fine control of gray levels with reduced artifacts. The described methods additionally require less memory to store all of the waveforms needed to achieve good performance of an electro-optic display over a range of temperatures.

Claims

1. A method for driving an electro-optic display having a plurality of pixels, each of which is capable of achieving at least two different gray levels, the method comprising:

storing a base waveform defining a sequence of voltages to be applied to a pixel during a specific transition by the pixel between gray levels at a first temperature and a base frame rate;

storing a temperature-dependent multiplication factor, n, where n is a positive number; and

effecting the specific transition by applying to the pixel the base waveform at a frame rate that that is n times the base frame rate.

2. The method of claim 1, wherein the base frame rate is between 1 Hz and 200 Hz.

3. The method of claim 2, wherein the base frame rate is between 40 Hz and 80 Hz.

4. The method of claim 3, wherein the base frame rate is about 50 Hz.

5. The method of claim 1, wherein the base waveform comprises a set of bits.

6. The method of claim 1, wherein the base waveform is DC balanced.

7. The method of claim 1, wherein the temperature-dependent multiplication factor, n, is stored in a look-up table (LUT).

8. The method of claim 7, further comprising obtaining a temperature measurement, and matching a value of n to the measured temperature.

9. The method of claim 1, further comprising:

storing a temperature dependent multiplication factor, p, wherein p is a positive number; and

adjusting the amplitude of the base waveform by a factor of p.

10. The method of claim 9, wherein the amplitude of the base waveform is between 2 Volts and 60 Volts.

11. The method of claim 10, wherein the amplitude of the base waveform is between 4 Volts and 21 Volts.

12. The method of claim 11, wherein the amplitude of the base waveform is about 15 Volts.

13. The method of claim 9, wherein the temperature-dependent multiplication factor, p, is stored in a look-up table (LUT).

14. The method of claim 13, further comprising obtaining a temperature measurement, and matching a value of p to the measured temperature.

15. The method of claim 1, wherein the electro-optic display comprises an electrophoretic medium.