Four-channel transmissive display system

• US 9,659,532 B2
• Filed: 04/20/2016
• Issued: 05/23/2017
• Est. Priority Date: 07/14/2008
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Inventors: White, Christopher J., Miller, Michael E.
• Primary Examiner(s): Lee, Benjamin C
• Assistant Examiner(s): LEE, DAVID J
• Application Number:
  US15/133,603
• Publication Number:
  US 20160247462A1
• Time in Patent Office: 398 Days
• Field of Search: None
• 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 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/0613 The adjustment depending on the type of the information to be displayed
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/3208 organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• 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 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 5/04 using circuits for interfacing with colour displays
• CPC Class Codes: G09G 5/10 Intensity circuits

Abstract

A four-color transmissive display system incorporates a display having independently variable light sources for different colors, and a controller. The controller is configured to receive and process a three-color input image signal, and provide a four-color output image signal to the display. The controller incorporates units respectively configured to (1) calculate a blue reduction factor for each pixel, dependent on luminance differences between blue and other color components, (2) produce respective saturation adjustment factors for red, green, and blue, (3) apply the blue reduction factor to reduce blue luminance, and apply the saturation adjustment factors to reduce saturation of other colors, (4) produce the output image signal. An optional sensor is operable to provide a control signal to the controller, whereby display power can be reduced. An optional estimating unit is configured to estimate current required to display the input image signal, for adjustment of the output image signal.

Claims

1. A transmissive display system, comprising:

a) a display device comprising a plurality of pixels and a plurality of light sources,

wherein each pixel comprises four transmissive subpixels operable to transmit light of respective colors,

wherein the four colors are red, green, and blue, which define a color gamut, and white, which lies within the color gamut

wherein light sources for different color subpixels are independently variable;

b) a controller comprising;

i) a reduction factor calculation unit,

ii) a saturation adjustment factor selection unit,

iii) a factor application unit, and

iv) a display drive unit;

wherein the controller is configured to

i) receive an input image signal comprising a plurality of input pixel signals, each input pixel signal having three color components,

ii) process the input image signal to produce an output image signal, and

iii) provide the output image signal to the display device;

wherein the reduction factor calculation unit is configured to calculate a blue reduction factor for only the blue color component of each input pixel signal,

wherein the blue reduction factor is dependent on the differences in luminance of the blue color component and the other color components;

wherein the saturation adjustment factor selection unit is configured to produce respective saturation adjustment factors for each of the red, green, and blue color components,

wherein at least two of the saturation adjustment factors are unequal;

wherein the factor application unit is configured to apply the blue reduction factors to reduce luminance of the blue color component, and apply the saturation adjustment factors to reduce saturation of other color components; and

wherein the display drive unit is configured to produce the output image signal,

wherein the output image signal has four color components which are red, green, blue, and white.

2. The transmissive display system of claim 1, further comprising a sensor operable to provide a control signal to the controller, and wherein the saturation adjustment factor unit is configured to produce saturation adjustment factors that are dependent upon the control signal.

3. The transmissive display system of claim 2, wherein the control signal is responsive to a battery lifetime signal, whereby the transmissive display system is configured to reduce power to the display device when the battery lifetime is low.

4. The transmissive display system of claim 2, wherein the control signal is responsive to a power type signal, whereby the transmissive display system is configured to reduce power to the display device when a limited type of power is applied.

5. The transmissive display system of claim 2, wherein the sensor is configured to adjust the control signal according to a type of input image, whereby the control signal is responsive to an input type signal.

6. The transmissive display system of claim 1, wherein the controller further comprises an estimating unit configured to receive the input image signal, analyze the input image signal, estimate the current required to display the input image signal, and provide a control signal to the saturation adjustment factor selection unit,

wherein the saturation adjustment factor unit is configured to produce saturation adjustment factors that are dependent upon the control signal, and

whereby the transmissive display system is configured to adjust the output image signal according to the current required to display the input image signal.

7. The transmissive display system of claim 1, wherein the controller further comprises a gain selection unit and a gain application unit respectively configured to select a luminance gain and apply the luminance gain to the input image signal.

8. The transmissive display system of claim 1, wherein the saturation adjustment factor for the blue color component is 1.0.

9. The transmissive display system of claim 1, wherein the controller is further configured to convert the input image signal from an input color space to primary colors of the display device.

10. The transmissive display system of claim 1, wherein the display is a liquid crystal display.

11. The transmissive display system of claim 1, wherein the light sources are individually controllable inorganic LEDs.

12. The transmissive display system of claim 11, wherein each inorganic LED provides illumination to a plurality of subpixels.

13. The transmissive display system of claim 12, wherein the system is configured to drive each inorganic LED at a level that is capable of providing the luminance required by the highest luminance subpixel within an area that is illuminated by the inorganic LED.

14. The transmissive display system of claim 12, wherein the system is configured to clip the luminance of high-luminance subpixels from among the plurality of subpixels illuminated by an inorganic LED.