Increasing brightness in field-sequential color displays

• US 7,046,221 B1
• Filed: 10/09/2001
• Issued: 05/16/2006
• Est. Priority Date: 10/09/2001
• Status: Expired due to Fees

• Current Assignee: Citizen Finetech Miyota Company Limited (Citizen Electronics Company Limited)
• Original Assignee: DT FLCO, Inc. (Micron Technology, Inc.)
• Inventors: Malzbender, Rainer M
• Primary Examiner(s): Lefkowitz, Sumati
• Assistant Examiner(s): ENGLISH, ALECIA DIANE
• Application Number:
  US09/974,437
• Time in Patent Office: 1,680 Days
• Field of Search: 345 82- 83, 345 88- 89, 345/32, 345/33, 345/39, 345/102
• US Class Current: 345/82
• 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 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/063 Waveforms for resetting the whole screen at once
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources

Abstract

A display system includes a display panel having an array of pixels, the pixels having ON states and OFF states. The pixels form images by modulating light in a temporal sequence during an image frame in response to drive signals generated from incoming video data. A light source arrangement that emits at least two colors of light illuminates the display panel. The image frame is divided into color segments with only one color of light being emitted from the light source during each segment. The color segments are further divided into grayscale periods. Transition segments are provided for the transitions between colors. The state of each pixel during these transition segments is a function of the desired brightness level for each pixel, as derived from incoming video data.

Claims

1. A display, comprising:

a display panel, the panel having a plurality of pixels configured to modulate light in a temporal sequence so as to form an image during a frame, the pixels having a plurality of light modulating states, including OFF and ON;

a light source arrangement that illuminates the display panel, the light source arrangement being configured to selectively emit light of at least one of at least three different colors; and

a data ordering arrangement that is receptive of incoming video data and that generates drive signals that drive the pixels to the light modulating states;

wherein the frame is divided time-wise into multiple color segments and multiple transition periods, the color segments being time periods where the light source arrangement emits, and illuminates the panel with, only one of the different colors of light, wherein between each two of the color segments is a transition period, the transition period being a time period where the light source arrangement emits, and illuminates the panel with, varying amounts of two of the at least three different colors of light, wherein the incoming video data includes information from which the data ordering arrangement determines pixel brightness values for each color segment, wherein the drive signals cause certain individual pixels to be in the same state other than the OFF state during each of the transition periods of a frame.

2. A display as defined in claim 1, wherein the number of color segments is at least three.

3. A display as defined in claim 2, wherein the light source arrangement illuminates the panel with red light during one color segment, green light during a different color segment and blue light during a different color segment.

4. A display as defined in claim 3, further comprising a compensator cell having at least two states, one state wherein the compensator has no effect on the appearance to a viewer of individual pixels, and a second state wherein the compensator changes the appearance of pixels by inverting the contrast of the image, and wherein the compensator changes from the first state to the second state at least once during the frame.

5. A display as defined in claim 4, wherein the compensator changes state during the color segment during which the light source is illuminating the display panel with blue light.

6. A display as defined in claim 1, wherein the intensity of the different colors of light illuminating the panel during the transition periods is adjustable to maintain a stable white point.

7. A display as defined in claim 1, further comprising a temperature sensing arrangement that senses the temperature of the light source arrangement, wherein the intensity of the different colors of light illuminating the panel during the transition periods is adjustable to maintain a stable white point in response to the temperature of the light source arrangement.

8. A display as defined in claim 1, wherein the light source arrangement includes color filters.

9. A display as defined in claim 1, wherein the light source arrangement includes a color wheel.

10. A display as defined in claim 9, wherein the color wheel is divided into at least three color areas.

11. A display as defined in claim 10, wherein the color wheel includes red, green and blue color areas.

12. A display as defined in claim 11, wherein the color wheel includes at least one broadly-transmissive area that passes a substantial amount of light across the visible light spectrum.

13. A display as defined in claim 12, wherein the color wheel includes at least one broadly-transmissive area between each color area.

14. A display as defined in claim 13, wherein the light illuminating the panel during a transition segment travels through a broadly-transmissive area of the color wheel.

15. A display as defined in claim 1, wherein the state of a pixel during the transition periods is determined by the pixel brightness values.

16. A display as defined in claim 15, wherein pixels with pixel brightness values above predetermined values for each color segment in a given frame are in a state other than OFF during the transition periods corresponding to the frame.

17. A display as defined in claim 15, wherein the color switching device is a color wheel.

18. A display as defined in claim 15, wherein the color switching device includes one or more color filters.

19. A display as defined in claim 15, wherein substantially the same drive signals are provided to the pixels by the data ordering arrangement during each transition period in a frame.

20. A display, comprising:

a display panel, the panel having a plurality of pixels configured to modulate light so as to form an image during a frame, the pixels having a plurality of light modulating states, including OFF and ON;

a light source arrangement that illuminates the display panel, the arrangement including a broad-spectrum source of light and a color switching device to control the color of light emitted by the arrangement, the light source arrangement being configured to selectively emit light of at least one of at least three different colors, a first color, a second color, and a third color; and

a data ordering arrangement that is receptive of incoming video data and that generates drive signals that drive the pixels to the light modulating states;

wherein the frame is divided time-wise into color segments, the color segments being time periods where the light source arrangement emits, and illuminates the panel with, only one of the different colors of light, wherein between each two of the color segments is a transition period that is relatively shorter in time duration than the color segments, the transition period being a time period where the light source arrangement emits, and illuminates the panel with, varying amounts of two of the different colors of light there being one transition period during which varying amounts of the first and second color are emitted by the light source arrangement, a second transition period during which varying amounts of the second and third color are emitted by the light source arrangement, and a third transition period during which varying amounts of the first and third color are emitted by the light source arrangement;

wherein, depending on the incoming video data, the data ordering arrangement provides data to place certain pixels into an ON state during at least a portion of each of the transition periods to increase the amount of light in the displayed image, the increased light having a color that is a selected combination of the first, second, and third colors.

21. A display, comprising:

a display panel, the panel having a plurality of pixels configured to modulate light in a temporal sequence so as to form an image during a frame, the pixels having a plurality of light modulating states, including OFF and ON;

a light source arrangement that illuminates the display panel, the arrangement including a broad spectrum source of light and a color switching device to control the color of light emitted by the arrangement, the light source arrangement being configured to selectively emit light of at least one of at least three different primary additive colors, a first color, a second color, and a third color; and

a data ordering arrangement that is receptive of incoming video data and that generates drive signals that drive the pixels to the light modulating states;

wherein the frame is divided time-wise into color segments, the color segments being time periods where the light source arrangement emits, and illuminates the panel with, only one of the different primary additive colors of light, wherein between each two of the color segments is a transition period that is relatively shorter in time duration than the color segments, the transition period being a time period where the light source arrangement emits, and illuminates the panel with, varying amounts of two of the different primary additive colors of light;

wherein, depending on the incoming video data, the data ordering arrangement provides data to place certain pixels into an ON state during at least a portion of each of the transition periods to increase the amount of light in the displayed image, the increased light having a color that is a selected combination of the first, second, and third colors.