LIQUID CRYSTAL DISPLAY DEVICE AND METHOD OF CONTROLLING LIQUID CRYSTAL DISPLAY DEVICE

• US 20180261170A1
• Filed: 01/08/2016
• Published: 09/13/2018
• Est. Priority Date: 01/09/2015
• Status: Abandoned Application

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: SHIOMI, MAKOTO
• Application Number:
  US15/542,180
• Publication Number:
  US 20180261170A1
• Time in Patent Office: Days
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/062 Adjustment of illumination source parameters
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: H04N 9/30 using solid-state colour display devices

Abstract

Coloration changes on a liquid crystal display device are mitigated in a low gray level region. Gray level data for a first pixel indicates a first gray level, n pieces of gray level data for the first to n-th pixels indicate a saturation index for the first pixel that has a first index value, and the first pixel exhibits an optical transmittance that is equal to a first optical transmittance. Alternatively, gray level data for a first pixel indicates a first gray level, n pieces of gray level data for the first to n-th pixels indicate a saturation index for the first pixel that has a second index value, and the first pixel exhibits an optical transmittance that is equal to a second optical transmittance. The first index value is smaller than the second index value, and the first optical transmittance is greater than the second optical transmittance.

Claims

1. A liquid crystal display device comprising picture elements each composed of first to n-th pixels, a portion of a liquid crystal layer in each pixel being rendered to exhibit an optical transmittance that is in accordance with gray level data, wherein

both:

a case where gray level data for the first pixel indicates a first gray level, n pieces of gray level data for the first to n-th pixels indicate a saturation index for the first pixel that has a first index value, and the first pixel exhibits an optical transmittance that is equal to a first optical transmittance; and

a case where gray level data for the first pixel indicates a first gray level, n pieces of gray level data for the first to n-th pixels indicate a saturation index for the first pixel that has a second index value, and the first pixel exhibits an optical transmittance that is equal to a second optical transmittance

are possible,

the first gray level is included in a low gray level region that is a first half of all gray levels that can be indicated by the gray level data, and

the first index value is smaller than the second index value, and the first optical transmittance is greater than the second optical transmittance.

2. The liquid crystal display device according to claim 1, wherein the optical transmittance of the first pixel has a smaller dynamic range when (a) the gray level data for the first pixel is changed from a minimum to a maximum with the saturation index for the first pixel being fixed to the first index value than when (b) the gray level data for the first pixel is changed from the minimum to the maximum with the saturation index for the first pixel being fixed to the second index value.

3. The liquid crystal display device according to claim 1, wherein

the optical transmittance of the first pixel is set via a signal voltage inputted to the first pixel, and

the signal voltage inputted to the first pixel has a smaller dynamic range when (a) the gray level data for the first pixel is changed from a minimum to a maximum with the saturation index for the first pixel being fixed to the first index value than when (b) the gray level data for the first pixel is changed from the minimum to the maximum with the saturation index for the first pixel being fixed to the second index value.

4. The liquid crystal display device according to claim 1, wherein

the optical transmittance of the first pixel is set via a signal voltage inputted to the first pixel, and

the signal voltage inputted to the first pixel has a greater dynamic range when the gray level data for the first pixel is changed from a minimum to a maximum with the gray level data for the second to n-th pixels being fixed to the maximum than when the gray level data for the first pixel is changed from the minimum to the maximum with the gray level data for the second to n-th pixels being fixed to the minimum.

5. The liquid crystal display device according to claim 2, wherein

the dynamic range has a difference between (a) and (b) that corresponds to a part that corresponds to from a minimum gray level to a threshold gray level of the gray level data in (b), and

the threshold gray level is included in the low gray level region.

6. The liquid crystal display device according to claim 5, herein the threshold gray level is either equal to or lower than gray level 32 when the gray level data can indicate 256 gray levels.

7. The liquid crystal display device according to claim 5, wherein an optical transmittance that corresponds to the threshold gray level is less than or equal to 1% of an optical transmittance that corresponds to a maximum gray level.

8. The liquid crystal display device according to claim 7, wherein the optical transmittance that corresponds to the threshold gray level is greater than or equal to 0.1% and less than or equal to 1% of the optical transmittance that corresponds to the maximum gray level.

9. The liquid crystal display device according to claim 1, wherein the saturation index for the first pixel is determined using a relationship between the n pieces of gray level data for the first to n-th pixels and the gray level data for the first pixel.

10. The liquid crystal display device according to claim 1, wherein the saturation index for the first pixel is determined using a relationship between a maximum value and a minimum value indicated by the n pieces of gray level data for the first to n-th pixels.

11. The liquid crystal display device according to claim 1, further comprising a backlight that shines light onto a liquid crystal panel divided into a plurality of segmental areas, wherein the backlight is controlled so as to illuminate each individual segmental area with light having a luminance that is in accordance with a brightness of video to be displayed in that segmental area.

12. The liquid crystal display device according to claim 11, further comprising a first gray level correction table and a second gray level correction table representing a greater output dynamic range than does the first gray level correction table, wherein either the first or the second gray level correction table or both is/are applied to the gray level data depending on the saturation index for the first pixel, to perform saturation-specific gray level correction.

13. The liquid crystal display device according to claim 12, wherein the gray level data, after being subjected to the saturation-specific gray level correction, is adjusted with respect to a gray level of each segmental area in accordance with luminance of light illuminating that segmental area.

14. The liquid crystal display device according to claim 12, wherein the gray level data, after being adjusted with respect to a gray level of each segmental area in accordance with luminance of light illuminating that segmental area, is subjected to the saturation-specific gray level correction.

15. A method of controlling a liquid crystal display device comprising picture elements each composed of first to n-th pixels, a portion of a liquid crystal layer in each pixel being rendered to exhibit an optical transmittance that is in accordance with gray level data, wherein

both:

a case where gray level data for the first pixel indicates a first gray level, n pieces of gray level data for the first to n-th pixels indicate a saturation index for the first pixel that has a first index value, and the first pixel exhibits an optical transmittance that is equal to a first optical transmittance; and

a case where gray level data for the first pixel indicates a first gray level, n pieces of gray level data for the first to n-th pixels indicate a saturation index for the first pixel that has a second index value, and the first pixel exhibits an optical transmittance that is equal to a second optical transmittance

are possible,

the first gray level is included in a low gray level region that is a first half of all gray levels that can be indicated by the gray level data, and

the first index value is smaller than the second index value, and the first optical transmittance is greater than the second optical transmittance.