System and method for intensity control of a pixel

• US 7,023,457 B2
• Filed: 03/13/2001
• Issued: 04/04/2006
• Est. Priority Date: 03/13/2001
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Kling, Ralph M., Huang, Samson X.
• Primary Examiner(s): Awad, Amr A.
• Assistant Examiner(s): SHENG, TOM V
• Application Number:
  US09/805,755
• Publication Number:
  US 20020130883A1
• Time in Patent Office: 1,848 Days
• Field of Search: 345/63, 345/77, 345 87- 89, 345690-696, 349/84, 349/85
• US Class Current: 345/690
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2074 using sub-pixels
• CPC Class Codes: G09G 3/2081 with combination of amplitude modulation and time modulation space and time error diffusion G09G3/2066
• 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

Abstract

An LCOS chip may have a pixel divided into an outer subpixel and an inner subpixel. A driver may independently drive the subpixels. The driving technique may be pulse-width modulation. Because of the pixel is divided into subpixels, pulses of short widths that drive an undivided pixel may be replaced with pulses of longer duration. In an alternative embodiment, the pixel is not divided into subpixels. The driving technique may be a combination of pulse width and pulse height modulation. The waveform may replace pulses of short widths with pulses of longer duration and reduced voltage levels.

Claims

1. A system for intensity control of a pixel having 2^N gray-scale tones, comprising:

a pixel having 2^s subpixels, two of the subpixels with the lowest light output having a light output ratio of about 1;

1; and

a driver to apply a pulse-width modulated waveform to the subpixels, the modulated waveform having N-s pulses of different pulse widths combined to provide the 2^N gray-scale tones,

where N is a positive integer and s is a positive integer having a value less than N.

2. The system of claim 1, the least-significant pulse width and the next-to-the-least-significant pulse width each have a width of 2^s/2^N.

3. The system of claim 2, the least-significant pulse width being applied to a one of the two subpixels with the lowest light output to obtain a first gray-scale tone.

4. The system of claim 2, the next-to-the-least-significant pulse width being applied to the two subpixels with the lowest light output to obtain a second gray-scale tone.

5. The system of claim 2, the least-significant pulse width being applied to a one of the two subpixels with the lowest light output and the next-to-the-least-significant pulse width being applied to the two subpixels with the lowest light output to obtain a third gray-scale tone.

6. The system of claim 1, the 2^s subpixels being concentric.

7. A system for intensity control of a pixel, comprising:

a first subpixel;

a second subpixel, the first subpixel and the second subpixel having a light output ratio of substantially 1;

1; and

a driver to apply a pulse-width modulated electrical waveform to the first subpixel and the second subpixel, the modulated waveform having a first pulse and a second pulse, the first pulse being applied to the first subpixel and the second pulse being applied to the first subpixel and the second subpixel, wherein the first pulse and the second pulse being of about equal width.

8. The system of claim 7, the modulated waveform having a third pulse being substantially twice the width of the first pulse, the third pulse being applied to the first subpixel and the second subpixel.

9. The system of claim 7, the first pulse and second pulse being of unequal amplitude.

10. The system of claim 7, the first subpixel and the second subpixel being concentric.

11. A method of intensity control of a pixel, comprising:

applying a first electrical pulse with a first width to a first subpixel of the pixel to produce a first gray-scale tone; and

applying a second electrical pulse with the first width to the first subpixel and a second subpixel of the pixel to produce a second gray-scale tone,

wherein the first subpixel and the second subpixel have a light output ratio of substantially 1;

1.

12. The method of claim 11 further comprising applying the first pulse to the first subpixel and the second pulse to the first subpixel and the second subpixel to produce a third gray-scale tone.

13. The method of claim 11 further comprising applying a third electrical pulse with a second width substantially twice the first width to the first subpixel and the second subpixel to produce a fourth gray-scale tone.

14. The method of claim 11 further comprising applying the first pulse to the first subpixel and a third electrical pulse with a second width substantially twice the first width to the first subpixel and the second subpixel to produce a fifth gray-scale tone.