Apparatus for providing light source modulation in dual modulator displays

• US 9,099,046 B2
• Filed: 03/17/2014
• Issued: 08/04/2015
• Est. Priority Date: 02/24/2009
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Whitehead, Lorne A., Ward, Gregory John, Silverstein, Louis D., Seetzen, Helge
• Primary Examiner(s): Lao, Lun-Yi
• Assistant Examiner(s): Hegarty, Kelly B
• Application Number:
  US14/215,856
• Publication Number:
  US 20140198142A1
• Time in Patent Office: 505 Days
• Field of Search: 345/3.1, 345/4, 345/30, 345/44, 345/73, 345/76.2, 345/204, 313/522
• US Class Current: 1/1
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/32 semiconductive, e.g. using light-emitting diodes [LED]
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/3433 using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices using liquid crystal devices G09G3/36; using electrochromic devices G09G3/38
• 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

Abstract

Dual modulator displays are disclosed incorporating a phosphorescent plate interposed in the optical path between a light source modulation layer and a display modulation layer. Spatially modulated light output from the light source modulation layer impinges on the phosphorescent plate and excites corresponding regions of the phosphorescent plate which in turn emit light having different spectral characteristics than the light output from the light source modulation layer. Light emitted from the phosphorescent plate is received and further modulated by the display modulation layer to provide the ultimate display output.

Claims

1. A display comprising:

a light source layer comprising light sources;

a display modulation layer comprising an array of modulation elements;

a controller configured to receive image data and to determine first drive signals for the light source layer based at least in part on the image data, the light source layer configured to emit a first spatially varying light pattern in response to the first drive signals;

a conversion layer interposed in an optical path between the light source modulation layer and the display modulation layer and configured to receive the first spatially varying light pattern, the conversion layer comprising one or more phosphorescent materials configured to cause a second spatially varying light pattern in response to receiving the first spatially varying light pattern, the second spatially varying light pattern having a spectral distribution different from that of the first spatially varying light pattern;

wherein the controller is configured to determine second drive signals for the modulation elements of the display modulation layer based at least in part on the image data and estimated expected characteristics of the second spatially varying light pattern made using a transfer function model relating the first spatially varying light pattern received at the conversion layer to the second spatially varying light pattern affected by the phosphorescent materials in the conversion layer and received at the display modulation layer;

wherein the controller is configured to determine an estimate of the expected characteristics of the second spatially varying light pattern received at the display modulation layer based at least in part on the first drive signals and modified point spread functions of the light sources, the modified point spread functions incorporating the transfer function of the phosphorescent materials; and

wherein the conversion layer comprises a patterned plurality of regions, each region comprising a plurality of sub-regions, and the plurality of sub-regions within each region comprise a red sub-region which emits light having a generally red central wavelength, a green sub-region which emits light having a generally green central wavelength and a blue sub-region which emits light having a generally blue central wavelength.

2. A display according to claim 1, wherein the conversion layer is contiguous with the display modulation layer.

3. A display according to claim 1, wherein the conversion layer is spaced apart from the display modulation layer by a distance less than or equal to five times a dimension of the modulation elements of the display modulation layer.

4. A display according of claim 1, wherein each sub-region comprising one or more materials which cause the sub-region to emit light having a unique spectral distribution relative to the other sub-regions within the same region in response to receiving light from the first spatially varying light pattern.

5. A display according to claim 4 wherein the plurality of sub-regions within each region comprise a red sub-region comprising “

red”

quantum dots configured to emit red light, a green sub-region comprising “

green”

quantum dots configured to, emit green light, and a blue sub-region comprising “

blue”

quantum dots configured to emit blue light and wherein the conversion layer is configured so as to have properties that influences a Point Spread Function (PSF) of light received at the display modulation layer so as to provide an increase at a tail of the PSF relative to a center of the PSF.

6. A display according to claim 4 wherein the plurality of sub-regions within each region comprise a red sub-region which emits light having a central wavelength of about 575 nm (±

5%) and having a full-width half-maximum (FWHM) spread in a range of 110 nm-130 nm, a green sub-region which emits light having a central wavelength of 540 nm (±

5%) and having a FWHM spread in a range of 90 nm-110 nm and a blue sub-region which emits light having a central wavelength of about 450 nm (±

5%) and having a FWHM spread in a range of 40 nm-60 nm.

7. A display according to claim 4 wherein the plurality of sub-regions within each region comprise a red sub-region which emits light having a central wavelength of about 575 nm (±

10%) and having a full-width half-maximum (FWHM) spread in a range of 110 nm-130 nm, a green sub-region which emits light having a central wavelength of 540 nm (±

10%) and having a FWHM spread in a range of 90 nm-110 nm and a blue sub-region which emits light having a central wavelength of about 450 nm (±

10%) and having a FWHM spread in a range of 40 nm-60 nm.

8. A display according to claim 4, wherein the light emitted from the plurality of sub-regions within each region overlaps when received at the display modulation layer to form a contribution to the second spatially varying light pattern received at the display modulation layer.

9. A display according to claim 8, wherein a resolution of the patterned plurality of regions is greater than or equal to a resolution of the first spatially varying light pattern and less than or equal to a resolution of the display modulation layer.

10. A display according to claim 8, wherein the light sources comprise LEDs and the conversion layer comprises a phosphorescent plate and wherein the controller is configured to determine an estimate of the expected characteristics of the second spatially varying light pattern received at the display modulation layer based at least in part on the first drive signals and modified point spread functions of the LEDs, the modified point spread functions incorporating the transfer function of the phosphorescent plate which relates light received on the phosphorescent plate to the second spatially varying light pattern.

11. The display according to claim 10, wherein the conversion layer comprises quantum dots.

12. A display according to claim 1, wherein the controller is configured to determine a first estimate of the first spatially varying light pattern received at the conversion layer based at least in part on the first drive signals.

13. The display according to claim 1, wherein the conversion layer comprises quantum dots.

14. The display according to claim 1, wherein the conversion layer comprises quantum dots and is arranged to provide diffusion.

15. The display according to claim 1, wherein the light emitted by the conversion layer has a broadband spectral characteristic.

16. The display according to claim 15, wherein the light emitted by the conversion layer has a spectral distribution that includes more than 75% of the visible light spectrum.

17. The display according to claim 15, wherein the light emitted by the conversion layer has a multi-modal spectral distribution.

18. The display according to claim 15, wherein the light emitted by the conversion layer has a multi-modal spectral distribution that includes more than 50% of the visible light spectrum.

19. A method for displaying an image on a display comprising a light source layer and a display modulation layer incorporating an array of modulation elements, the method comprising:

receiving image data;

determining first drive signals, for the light source layer based at least in part on the image data, the first drive signals, when applied to the modulation elements of the light source modulation layer, causing the light source layer to emit a first spatially varying light pattern;

converting light in an optical path between the light source layer and the display modulation layer, the light conversion being performed via phosphorescent materials in a conversion layer comprising a patterned plurality of regions, each region comprising a plurality of sub-regions, and the plurality of sub-regions within each region comprise a red sub-region which emits light having a generally red central wavelength, a green sub-region which emits light having a generally green central wavelength, and a blue sub-region which emits light having a generally blue central wavelength which emit a second spatially varying light pattern in response to receiving the first spatially varying light pattern, the second spatially varying light pattern affected by the phosphorescent materials and having a spectral distribution different from that of the first spatially varying light pattern;

determining second drive signals for the modulation elements of the display modulation layer based at least in part on the image data and estimated expected characteristics of the second spatially varying light pattern made using a transfer function model relating the first spatially varying light pattern received at the conversion layer to the second spatially varying light pattern received at the display modulation layer;

wherein said determining is based at least in part on the first drive signals and modified point spread functions of the light source layer, the modified point spread functions incorporating the transfer function of the phosphorescent materials; and

displaying the image by applying the first drive signals to the light source layer and the second drive signals to the display modulation layer.

20. The method according to claim 19, wherein the materials comprise quantum dots intersperced in a contiguous plane between the light source layer and the display modulation layer.

21. The method according to claim 19, wherein the materials comprise a combination of diffuser materials and one of quantum dots, photo-luminescents, and phosphors.

22. The method according to claim 19, wherein the individually modulated light sources comprise LEDs and the light output characteristics of the individually modulated light sources comprise point spread functions of the LEDs.

23. The method according to claim 22, comprising determining a first estimate of the first spatially varying light pattern and determining a second estimate of the expected characteristics of the second spatially varying light pattern received at the display modulation layer based at least in part on the first estimate.

24. The method according to claim 23, comprising determining the second estimate based at least in part on light output characteristics of the materials.

25. The method according to claim 24, wherein the light output characteristics of the materials comprise a transfer function which relates light received on the materials to light output by the materials.

26. The method according to claim 19, wherein the light source layer comprises LEDs and wherein the method comprises determining an estimate of the expected characteristics of the second spatially varying light pattern received at the display modulation layer based at least in part on the first drive signals and modified point spread functions of the LEDs, the modified point spread functions incorporating a transfer function of the materials which relates light received on the materials to light output by the materials.

27. The display according to claim 26, wherein the materials comprise a contiguous plate comprising quantum dots between the light source layer from the display modulation layer.

28. The display according to claim 27, wherein a thickness of the phosphorescent plate varies according to the point spread function of the first spatially variable light pattern to achieve a desirable second spatially variable light pattern.

29. The display according to claim 27, wherein a density of the phosphorescent plate varies according to the point spread function of the first spatially variable light pattern to achieve a desirable second spatially variable light pattern.

30. The display according to claim 27, wherein the second drive signals for the modulation elements of the display modulation layer are based at least in part on the estimate of the expected characteristics of the second spatially varying light pattern received at the display modulation layer.

31. The display according to claim 27, wherein the first drive signals for the light source layer are based at least in part on the estimate of the expected characteristics of the second spatially varying light pattern received at the display modulation layer.

32. The display according to claim 27, wherein the estimate of the expected characteristics of the second spatially varying light pattern received at the display modulation layer incorporates a time-varying model to accommodate any degradation of the conversion layer.