Display region architectures

• US 20060066640A1
• Filed: 01/21/2005
• Published: 03/30/2006
• Est. Priority Date: 09/27/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Sampsell, Jeffrey B., Kothari, Manish
• Granted Patent: US 7,893,919 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• 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 2300/0465 Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness
• 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 3/2074 using sub-pixels
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

A bit depth of a pixel comprising multiple display elements, such as interferometric modulators, may be increased through the use of display elements having different intensities, while the lead count is minimally increased. An exemplary pixel with at least one display element having an intensity of 0.5 and N display elements each having an intensity of one can provide about 2N+1 shades (e.g., 0, 0.5, 1.0, 1.5, 2.0, [N+0.5]). In comparison, a pixel having N display elements, each having an intensity of one, can only provide about N+1 shades (e.g., 0, 1, 2, . . . , N). Thus, using at least one display element having an intensity lower than the intensity of each of the other display elements increases the number of shades provided by the pixel by an approximate factor of two and increases the bit depth of the pixel, while minimizing the number of additional leads.

Claims

1. A pixel having a bit depth per color, the pixel comprising:

a plurality of substantially equally sized sub-regions having a first group of sub-regions and a second group of sub-regions, wherein each of the sub-regions of the first group includes a first number of display elements per color and each of the sub-regions of the second group includes a second number of display elements per color, wherein the second number minus the first number is substantially equal to two raised to a power that is less than the bit depth per color.

2. The pixel of claim 1, wherein each of the display elements in the second group of sub-regions includes c+2^(n-p) display elements, where c is the number of display elements per sub-region per color in the first group, n is the bit depth per color of the pixel, and p is less than n.

3. The pixel of claim 2, wherein the sub-regions are arranged in N rows and M columns, each row and column being driven by at least one lead, wherein a total number of leads driving all of the display elements in the pixel is [(N+M)·

c]+2^(n-p).

4. The pixel of claim 1, wherein each sub-region of the second group has a unique size.

5. A pixel having a bit depth, the pixel comprising:

a plurality of substantially equally sized display elements each having an “

on”

position and an “

off”

position, wherein the display elements each emit visible light when in the “

on”

position, the plurality of substantially equally sized display elements includes a first group of display elements and a second group of display elements, the display elements of the first group each having an intensity of a predetermined value when in the “

on”

position and the display elements of the second group each having an intensity of a fraction of the predetermined value when in the “

on”

position, an intensity of the pixel being equal to an intensity of each of the plurality of display elements in the “

on”

position.

6. The pixel of claim 5, further comprising a third group of display elements, the display elements of the third group each having an intensity of less than the fraction of the predetermined value when in the “

on”

position, the intensity of the pixel being equal to an intensity of each of the plurality of display elements in the “

on”

position.

7. The pixel of claim 5, wherein an intensity of at least one of the display elements of the second group is configured to change according to a driver signal.

8. The pixel of claim 5, wherein the display elements of the second group include masking that reduces the aperture of the display elements.

9. The pixel of claim 5, wherein at least one of the display elements of the second group has an intensity of one-half the predetermined value.

10. The pixel of claim 5, wherein at least one of the display elements of the second group has an intensity of one-quarter the predetermined value.

11. The pixel of claim 5, wherein the display elements of the second group are masked to provide non-linear increments of intensity up to the predetermined value.

12. The pixel of claim 11, wherein the second group comprises at least four display elements, the at least four display elements having respective intensities of 0.1, 0.2, 0.4, and 0.8 of the predetermined value.

14. The pixel of claim 5, wherein p represents a bit depth of (N+M) substantially equally sized sub-regions each having c display elements per color.

13. A pixel having a bit depth n per color, the pixel comprising:

a first number N of sub-regions, each sub-region having c display elements per color, wherein each display element has a first area; and

a second number M of sub-regions, each sub-region having c+2^(n-p) display elements per color, wherein each of (c−

1) of the display elements has a second area and each of 1+2^(n-p) of the display elements has a third area, wherein the first area and the second area are substantially equal and the third area is substantially equal to the first area divided by 1+2^(n-p), wherein p is less than n.

15. A method of arranging a plurality of display elements in a pixel, the method comprising:

dividing the pixel into a first group of sub-regions and a second group of sub-regions, wherein the sub-regions in the first and second groups have substantially equal areas;

allocating a first number of display elements per color to each of the sub-regions of the first group; and

allocating a second number of display elements per color to each of the sub-regions of the second group, wherein the second number minus the first number is substantially equal to two raised to a power that is less than a bit depth per color of the pixel.

16. A display device responsive to signals having a plurality of bits, the display device comprising:

a plurality of pixels, each of the pixels comprising a plurality of sub-regions;

a first plurality of sub-regions, each sub-region having a first area, the first plurality of sub-regions responsive to a first portion of the plurality of bits; and

a second plurality of sub-regions, each sub-region having a second area, wherein the second area is less than the first area, the second plurality of sub-regions responsive to a second portion of the plurality of bits, wherein the bits of the second portion are less significant than the bits of the first portion.

17. The pixel of claim 16, wherein K is a number of bits in the first portion and the plurality of sub-regions comprises 2^K+2−

4 sub-regions.

18. The pixel of claim 16, wherein the first plurality of sub-regions comprises more than about 90 percent of an aperture of the pixel.

19. The pixel of claim 16, wherein the first plurality of sub-regions comprises more than about 98 percent of an aperture of the pixel.

20. The pixel of claim 16, wherein the second plurality of sub-regions comprises one or more rows of sub-regions disposed between rows of the sub-regions of the first plurality of sub-regions.

21. The pixel of claim 16, wherein the second plurality of sub-regions comprises one or more columns of sub-regions disposed between columns of the sub-regions of the first plurality of sub-regions.

22. The pixel of claim 16, wherein the second plurality of sub-regions comprises one or more rows of sub-regions disposed between rows of the sub-regions of the first portion of sub-regions and one or more columns of sub-regions disposed between columns of the sub-regions of the first portion of sub-regions.