Multi-primary color display device

• US 9,886,932 B2
• Filed: 09/02/2013
• Issued: 02/06/2018
• Est. Priority Date: 09/07/2012
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Yoshida, Yuichi, Tomizawa, Kazunari, Mori, Tomohiko, Hasegawa, Makoto
• Primary Examiner(s): CHOW, JEFFREY J
• Application Number:
  US14/426,468
• Publication Number:
  US 20150235615A1
• Time in Patent Office: 1,618 Days
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 5/028 Circuits for converting colour display signals into monochrome display signals
• CPC Class Codes: H04N 1/6025 using look-up tables

Abstract

A multi-primary color display device (100) includes: a multi-primary color display panel (10) including a pixel that is defined by a plurality of sub pixels including a red sub pixel (R), a green sub pixel (G), a blue sub pixel (B), and a yellow sub pixel (Ye); and a signal converting circuit (20) converting a three-primary color image signal corresponding to three primary colors into a multi-primary color image signal corresponding to four or more primary colors. The signal converting circuit (20), in a case where a three-primary color image signal representing at least an achromatic color of a half tone is input, performs a signal conversion such that variations in luminance levels of the plurality of sub pixels are equalized.

Claims

1. A multi-primary color display device comprising:

a multi-primary color display panel including a pixel that is defined by a plurality of sub pixels including a red sub pixel, a green sub pixel, a blue sub pixel, and a yellow sub pixel; and

a signal converting circuit converting a three-primary color image signal corresponding to three primary colors into a multi-primary color image signal corresponding to four or more primary colors,

in a case where a three-primary color image signal representing at least an achromatic color of a half tone is input, the signal converting circuit performs a signal conversion such that variations in luminance levels of the plurality of sub pixels are equalized;

in a case where a three-primary color image signal representing an achromatic color of a 128/255 gray scale is input, the signal converting circuit performs a signal conversion such that a root mean square value of differences between an average luminance level of the plurality of sub pixels and luminance levels of the plurality of sub pixels is 0.023 or less; and

the signal converting circuit includes independent gamma processing circuitry that independently performs a gamma processing for each of the plurality of sub pixels.

2. The multi-primary color display device according to claim 1,

wherein the signal converting circuit includes multi-primary color implementing circuitry that generates a multi-primary color image signal based on an input three-primary color image signal, and

the signal converting circuit further includes luminance ratio adjusting circuitry that adjusts a multi-primary color image signal generated by the multi-primary color implementing circuitry such that variations in luminance levels of the plurality of sub pixels are equalized in a case where a three-primary color image signal representing at least an achromatic color of a half tone is input to the multi-primary color implementing circuitry.

3. The multi-primary color display device according to claim 2, wherein the luminance ratio adjusting circuitry performs adjustment of the multi-primary color image signal such that a luminance level of the yellow sub pixel that is defined by the multi-primary color image signal is lowered after the adjustment than before the adjustment, and luminance levels of the red sub pixel and the green sub pixel defined by the multi-primary color image signal are raised after the adjustment than before the adjustment.

4. The multi-primary color display device according to claim 2, wherein the luminance ratio adjusting circuitry performs the adjustment of the multi-primary color image signal such that Δ

E, which is a color difference between before and after the adjustment, of an achromatic color displayed by the pixel is 3.0 or less.

5. The multi-primary color display device according to claim 2, wherein, when the number of primary colors used for display is n, the multi-primary color implementing circuitry determines gray scale levels of (n−

3) primary colors among the n primary colors by referring to a lookup table based on the input three-primary color image signal and calculates gray scale levels of the remaining three primary colors among the n primary colors by performing calculation using the gray scale levels of the (n−

3) primary colors.

6. The multi-primary color display device according to claim 1,

wherein the signal converting circuit includes multi-primary color implementing circuitry that generates a multi-primary color image signal based on an input three-primary color image signal, and

in a case where the three-primary color image signal representing at least an achromatic color of a half tone is input, the multi-primary color implementing circuitry generates a multi-primary color image signal in which variations in luminance levels of the plurality of sub pixels are equalized.

7. The multi-primary color display device according to claim 6, wherein, when the number of primary colors used for display is n, the multi-primary color implementing circuitry determines gray scale levels of (n−

3) primary colors among the n primary colors by referring to a lookup table based on the input three-primary color image signal and calculates gray scale levels of the remaining three primary colors among the n primary colors by performing calculation using the gray scale levels of the (n−

3) primary colors.

8. The multi-primary color display device according to claim 7, wherein the multi-primary color implementing circuitry includes a lookup table memory storing the lookup table and calculation circuitry that performs the calculation.

9. The multi-primary color display device according to claim 1, wherein the three-primary color image signal representing at least the achromatic color of the half tone is a three-primary color image signal that represents an achromatic color of a 64/255 gray scale to a 200/255 gray scale.

10. The multi-primary color display device according to claim 1, wherein the plurality of sub pixels include a cyan sub pixel.

11. The multi-primary color display device according to claim 1, wherein the plurality of sub pixels include an additional red sub pixel.

12. The multi-primary color display device according to claim 1, wherein the multi-primary color display panel includes one pair of substrates facing each other and a liquid crystal layer disposed between the one pair of substrates.