ELECTRONIC ALIGNMENT OF PRIMARY COLOR PIXELS IN A SCANNED DISPLAY

• US 20090051828A1
• Filed: 08/22/2007
• Published: 02/26/2009
• Est. Priority Date: 08/22/2007
• Status: Active Grant

• Current Assignee: Microvision, Inc.
• Original Assignee: Microvision, Inc.
• Inventors: Jakuc, Maciej A., Freeman, Mark O., Brown, Margaret K., Champion, Mark, Swilley, Shawn M.
• Granted Patent: US 8,223,161 B2
• Time in Patent Office: Days
• US Class Current: 348/745
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 3/02 by tracing or scanning a light beam on a screen
• CPC Class Codes: H04M 1/0272 for a projector or beamer module assembly constructional features of projectors per se G03B21/00; constructional details of projectors using electronic spatial light modulators per se H04N9/31
• CPC Class Codes: H04N 1/50 Picture reproducers for halftone screening H04N1/52
• CPC Class Codes: H04N 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161
• CPC Class Codes: H04N 9/3164 using multiple light sources
• CPC Class Codes: H04N 9/3182 Colour adjustment, e.g. white balance, shading or gamut white balance per se H04N9/73; control of amplitude of colour signals H04N9/68; colour control circuits for displays in general G09G5/02, G09G3/2003, G09G3/3607

Abstract

An image generation apparatus provides correction for color offsets. Color offsets may be caused by misalignments in laser diodes or optics assemblies in a laser projector. The offsets may be measured during or after manufacture of the laser projector. An image buffer is responsive to the offset data to translate each color plane separately. The image buffer may include separately addressable portions for each color. Further, variable delay elements on the output of the image buffer may provide color offset correction. Interpolation provides further offset correction.

Claims

1. An image generation apparatus comprising:

a frame buffer to hold data corresponding to an image made up of display pixels;

a translation component to receive color image data and color offset data, the translation component operable to translate the color image data by color and to write translated color image data to the frame buffer; and

a row buffer coupled to the frame buffer to receive at least one row of pixel data from translated color image data.

2. The image generation apparatus of claim 1 further comprising:

a horizontal scan position determination component to periodically determine a horizontal scan position of a scan trajectory; and

an interpolation component coupled to receive pixel data from the row buffer and operable to interpolate between display pixels on either side of the horizontal scan position in the at least one row.

3. The image generation apparatus of claim 2 further comprising a vertical scan position determination component operable to approximate a vertical scan position of the scan trajectory as a different row for each horizontal sweep of the scan trajectory.

4. The image generation apparatus of claim 2 wherein the horizontal scan position determination component is operable to determine the horizontal scan position as a sine of an increasing angle plus a horizontal offset that is a function of color.

5. The image generation apparatus of claim 2 wherein the horizontal scan position determination component is operable to determine the horizontal scan position as (a sine of an increasing angle) times a multiplier.

6. An image generation apparatus comprising:

a frame buffer to hold color image data corresponding to an image made up of display pixels, the frame buffer being separately addressable by color;

frame buffer addressing logic coupled to receive vertical color offset information and coupled to provide row addresses to the frame buffer; and

a plurality of row buffers coupled to the frame buffer to receive at least one row of pixel data for each color in the frame buffer.

7. The image generation apparatus of claim 6 further comprising:

a horizontal scan position determination component to periodically determine a horizontal scan position of a scan trajectory; and

an interpolation component coupled to receive pixel data from the plurality of row buffers and operable to interpolate between display pixels on either side of the horizontal scan position.

8. The image generation apparatus of claim 7 further comprising a vertical scan position determination component to periodically determine a vertical scan position of the scan trajectory.

9. The image generation apparatus of claim 8 wherein the vertical scan position determination component is operable to determine the vertical scan position as a sum of sine functions.

10. The image generation apparatus of claim 8 wherein the horizontal and vertical scan position determination components include at least one lookup table to implement arbitrary scan trajectories.

11. The image generation apparatus of claim 8 wherein the vertical scan position determination component is operable to determine the vertical scan position as a linearly advancing position over time.

12. The image generation apparatus of claim 8 wherein the vertical scan position determination component is operable to determine the vertical scan position as a sine of an increasing angle.

13. The image generation apparatus of claim 7 wherein each of the plurality of row buffers is sized to hold a number of rows greater than or equal to the maximum possible number of rows traversed in a single horizontal sweep of the scan trajectory.

14. An image generation apparatus comprising:

a frame buffer to hold a plurality of rows of color pixel data corresponding to an image made up of display pixels;

a variable delay element coupled to an output of the frame buffer, the variable delay element responsive to vertical color offset information to delay at least one color by an integer number of rows; and

a row buffer to receive at least one row of color pixel data from the variable delay element.

15. The image generation apparatus of claim 14 further comprising:

a horizontal scan position determination component to periodically determine a horizontal scan position of a scan trajectory; and

an interpolation component coupled to receive pixel data from the row buffer and operable to interpolate between display pixels on either side of the horizontal scan position.

16. The image generation apparatus of claim 15 wherein the variable delay element includes at least one programmable FIFO.

17. The image generation apparatus of claim 16 wherein the variable delay element includes a plurality of multiplexers to steer image data corresponding to one color to the at least one programmable FIFO.

18. The image generation apparatus of claim 15 further comprising a vertical scan position determination component operable to determine a vertical scan position of the scan trajectory that includes an offset as a function of color.

19. The image generation apparatus of claim 18 wherein the interpolation component is further operable to interpolate between display pixels on either side of the vertical scan of the vertical scan position.

20. A mobile device comprising:

a laser projector to project an image, the laser projector including an image generation apparatus having a frame buffer to hold data corresponding to an image made up of display pixels, a translation component to receive the color image data and color offset data, the translation component operable to translate the color image data by color and to write translated color image data to the frame buffer, and a row buffer coupled to the frame buffer to receive at least one row of pixel data from translated color image data.

21. The mobile device of claim 20 wherein the image generation apparatus further includes a horizontal scan position determination component to periodically determine a horizontal scan position of a scan trajectory, and an interpolation component coupled to receive pixel data from the row buffer and operable to interpolate between display pixels on either side of the horizontal scan position in the at least one row.

22. The mobile device of claim 20 further comprising a communications receiver.

23. The mobile device of claim 20 further comprising a communications transceiver.

24. The mobile device of claim 23 wherein the communications transceiver is operable to communicate using cellular telephone signals.

25. A method comprising:

separately translating each color plane in a color image while writing the color image to a frame buffer;

retrieving at least one row of pixel data from the color image in the frame buffer;

determining a horizontal scan position of a scan trajectory;

horizontally interpolating between pixel data to the left and right of the horizontal scan position to determine a pixel intensity of a new pixel at the horizontal scan position; and

displaying the new pixel at the horizontal scan position.

26. The method of claim 25 further comprising:

determining a vertical scan position of the scan trajectory; and

vertically interpolating between pixel data above and below the vertical scan position; and

combining the horizontal and vertical interpolation to arrive at the pixel intensity of the new pixel at an intersection of the horizontal scan position and the vertical scan position.

27. The method of claim 25 wherein determining a horizontal scan position comprises adding a horizontal offset to a mathematical function of time.