Controller and methods for quantization and error diffusion in an electrowetting display device

Patent metadata

Field	Value
Publication number	US-2017193926-A1
Application number	US-201615087778-A
Country	US
Kind code	A1
Filing date	Mar 31, 2016
Priority date	Jan 5, 2016
Publication date	Jul 6, 2017
Grant date	—

Abstract

Systems and methods for driving an electrowetting display device including a plurality of sub-pixels are presented. A reflectance level of a first sub-pixel in the plurality of sub-pixels is set to a minimum reflectance level or a threshold reflectance level. A reflectance quantization error is determined and a second reflectance level of a second sub-pixel in the plurality of sub-pixels is set to a second target reflectance level of the second sub-pixel plus a first fraction of the reflectance quantization error. A third reflectance level of a third sub-pixel in the plurality of sub-pixels is set to a third target reflectance level of the third sub-pixel plus a second fraction of the reflectance quantization error, and a fourth reflectance level of a fourth sub-pixel in the plurality of sub-pixels is set to a fourth target reflectance level of the fourth sub-pixel plus a third fraction of the reflectance quantization error.

First claim

What is claimed is:

1 . An electrowetting display device, comprising:
a first support plate and a second support plate opposite the first support plate; a pixel region between the first support plate and the second support plate, the pixel region including a data line and a gate line for controlling a state of a first red sub-pixel of a plurality of red sub-pixels of the electrowetting display device, the first red sub-pixel in a first pixel of a plurality of pixels of the electrowetting display device; and a display controller including:
an input line for receiving image data for a plurality of source image pixels from an external image source, the image data for a corresponding source image pixel of the plurality of source image pixels including a brightness and color level for each of a red value, a green value and a blue value of a tuple representing the corresponding source image pixel; and
an output line for providing at least one display signal level corresponding to a quantized reflectance level of the first red sub-pixel for applying a voltage to a first electrode of the first red sub-pixel to establish a driving voltage of the first red sub-pixel,
wherein the display controller is configured to:
determine a first target reflectance level of the first red sub-pixel based at least in part on the image data for a first source image pixel of the plurality of source image pixels;
compare the first target reflectance level of the first red sub-pixel to a threshold reflectance level;
determine that the first target reflectance level is less than or equal to the threshold reflectance level;
set a reflectance level of the first red sub-pixel to the quantized reflectance level, wherein the quantized reflectance level is a minimum reflectance level or the threshold reflectance level;
determine a reflectance quantization error by comparing the quantized reflectance level to the first target reflectance level;
determine a second target reflectance level for a second red sub-pixel of a second pixel based at least in part on the image data for a second source image pixel of the plurality of source image pixels, the second pixel neighboring the first pixel in a first row of pixels of the plurality of pixels;
set a second reflectance level of the second red sub-pixel to the second target reflectance level plus a first fraction of the reflectance quantization error;
determine a third target reflectance level for a third red sub-pixel of a third pixel based at least in part on the image data for a third source image pixel of the plurality of source image pixels, the third pixel neighboring the first pixel, the third pixel in a second row of pixels of the plurality of pixels under the first row of pixels;
set a third reflectance level of the third red sub-pixel to the third target reflectance level plus a second fraction of the reflectance quantization error;
determine a fourth target reflectance level for a fourth red sub-pixel of a fourth pixel based at least in part on the image data for a fourth source image pixel of the plurality of source image pixels, the fourth pixel neighboring the first pixel, the fourth pixel in the second row of pixels; and
set a fourth reflectance level of the fourth red sub-pixel to the fourth target reflectance level plus a third fraction of the reflectance quantization error.

2 . The electrowetting display device of claim 1 , wherein the display controller is configured to determine a reflectance quantization error by calculating a difference between the first target reflectance level and the quantized reflectance value.

3 . The electrowetting display device of claim 1 , wherein the display controller is configured to determine the first target reflectance level based in part on a reflectance quantization error from a quantization of reflectance levels of a previously-analyzed red sub-pixel of the plurality of red sub-pixels.

4 . The electrowetting display device of claim 1 , wherein the display controller is configured to, before comparing the first target reflectance level of the first red sub-pixel to the threshold reflectance level:
determine a fifth target reflectance level of a white sub-pixel in the first pixel based on the image data for the first source image pixel; compare the fifth target reflectance level of the white sub-pixel to the threshold reflectance level; determine that the fifth target reflectance level of the white sub-pixel is less than the threshold reflectance level; set a reflectance level of the white sub-pixel to the minimum reflectance level; and distribute a portion of a reflectance of the white sub-pixel to each of a plurality of neighboring, non-white sub-pixels.

5 . A method of driving an electrowetting display device including a plurality of sub-pixels, the method comprising:
setting a first reflectance level of a first sub-pixel in the plurality of sub-pixels to a minimum reflectance level or a threshold reflectance level; determining a reflectance quantization error by comparing the first reflectance level of the first sub-pixel to a first target reflectance level of the first sub-pixel, the first target reflectance level of the first sub-pixel based at least in part on image data for a first source image pixel of a plurality of source image pixels; setting a second reflectance level of a second sub-pixel in the plurality of sub-pixels to a second target reflectance level of the second sub-pixel based at least in part on image data for a second source image pixel of the plurality of source image pixels plus a first fraction of the reflectance quantization error; setting a third reflectance level of a third sub-pixel in the plurality of sub-pixels to a third target reflectance level of the third sub-pixel based at least in part on image data for a third source image pixel of the plurality of source image pixels plus a second fraction of the reflectance quantization error; and setting a fourth reflectance level of a fourth sub-pixel in the plurality of sub-pixels to a fourth target reflectance level of the fourth sub-pixel based at least in part on image data for a fourth source image pixel of the plurality of source image pixels plus a third fraction of the reflectance quantization error.

6 . The method of claim 5 , wherein the first sub-pixel is in a first pixel of the electrowetting display device and the second sub-pixel is in a second pixel of the electrowetting display device, the method further comprising determining the first fraction is ½.

7 . The method of claim 6 , further comprising determining the first pixel and the second pixel are in a same row of pixels in the electrowetting display device.

8 . The method of claim 6 , wherein the third sub-pixel is associated with a third pixel of the electrowetting display device and the fourth sub-pixel is associated with a fourth pixel of the electrowetting display device, the method further comprising:
determining the second fraction is ¼; and determining the third fraction is ¼.

9 . The method of claim 8 , further comprising determining the third pixel and the fourth pixel are in a same row of pixels in the electrowetting display device.

10 . The method of claim 5 , further comprising, before setting a reflectance level of a first sub-pixel in the plurality of sub-pixels to a minimum reflectance level or a threshold reflectance level:
identifying a white sub-pixel adjacent to the first sub-pixel; determining a fifth target reflectance level of the white sub-pixel; comparing the fifth target reflectance level of the white sub-pixel to the threshold reflectance level; determining that the fifth target reflectance level of the white sub-pixel is less th

Assignees

• Amazon Tech Inc

Inventors

• De Greef Petrus Maria

Classifications

• G09G2300/0452

  Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components · CPC title

• G09G3/2003

  Display of colours (specific for liquid crystal displays G09G3/3607) · CPC title

• G09G2320/0626

  for control of overall brightness · CPC title

• G09G2310/08

  Details of timing specific for flat panels, other than clock recovery · CPC title

• G09G2330/021

  Power management, e.g. power saving · CPC title