Increase gray scales of projection system by reflecting light from mirror elements with non-uniform intensity distribution

• US 7,573,633 B2
• Filed: 06/25/2007
• Issued: 08/11/2009
• Est. Priority Date: 11/01/2003
• Status: Expired due to Fees

• Current Assignee: Olympus Corporation, Silicon Quest Kabushiki-Kaisha
• Original Assignee: Olympus Corporation, Silicon Quest Kabushiki-Kaisha
• Inventors: Maeda, Yoshihiro, Ichikawa, Hirotoshi, Arai, Kazuma, Ishii, Fusao
• Primary Examiner(s): Spector; David N
• Application Number:
  US11/821,955
• Publication Number:
  US 20070296924A1
• Time in Patent Office: 778 Days
• Field of Search: 345/84, 345/85, 345/690, 345/691, 359/292
• US Class Current: 359/292
• CPC Class Codes: G03B 21/008 using micromirror devices
• CPC Class Codes: G03B 21/14 Details
• CPC Class Codes: H04N 9/3114 by using a sequential colour filter producing one colour at a time
• CPC Class Codes: H04N 9/312 Driving therefor driving of electronic spatial light modulators in displays other than projection devices G09G3/34, G09G3/36; control of liquid crystal elements G02F1/133; control of micromechanical modulators G02B26/08
• CPC Class Codes: H04N 9/3152 for shaping the light beam beam shaping per se G02B27/09
• CPC Class Codes: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129

Abstract

Additional control flexibilities to generate more gray scales for an image display system is achieved by controlling the intensity distribution of the light projection from a light source to a deflecting mirror to further coordinate with the control of the intermediate states of the deflecting mirror. The control light source intensity distribution can provide incident light with wide varieties of intensity distributions including non-uniform, symmetrical and non-symmetrical, different distributions of polarizations, various cross sectional shapes of the incident lights and other combinations of all of the above variations. More stable and better control of gray scale control is also achieved by optimizing the intensity distributions of the incident light to produce the best visual effects of the image display.

Claims

1. A projection device receiving a light from a light source through an illumination optics for projecting to a spatial light modulator having a plurality of micromirrors controlled to different deflection angles, said projection device further comprising:

a controller that receives and applies an input signal to control each of said micromirrors to deflect to a first deflection angle along an ON direction and a second deflection angle along an OFF direction and to operate in an intermediate state for reflecting an intermediate light having an intermediate intensity between light intensities reflected by said micromirrors in said ON and OFF directions wherein said micromirrors reflect said intermediate light having a non-uniform and/or asymmetrical intensity distribution across a cross section of an intermediate light flux from the micromirrors.

2. The projection device of claim 1 wherein:

said micromirrors further reflect said intermediate light flux having a different cross sectional area from an optical pupil of an image projection lens along a projection light path for projecting an image on a display screen.

3. The projection device of claim 1 wherein:

said micromirrors further reflect said intermediate light flux having a different cross sectional shape that a shape of an optical pupil of an image projection lens along a projection light path for projecting an image on a display screen.

4. The projection device of claim 1 wherein:

said micromirrors further reflect said intermediate light flux having a cross section overlapped partially with an optical pupil of an image projection lens along a projection light path for projecting an image on a display screen.

5. The projection device of claim 1 wherein:

said micromirrors further reflect said intermediate light flux transmitted along a plurality of intermediate light flux cross sections with some of said cross sections overlapped partially with an optical pupil of an image projection lens and other intermediate light flux cross sections totally separated from said optical pupil of said image projection lens.

6. The projection device of claim 1 wherein:

said micromirrors further reflect said intermediate light flux transmitted along a plurality of intermediate light flux cross sections with some of said cross sections having different cross section areas from an area of an optical pupil of an image projection lens along a projection light path for projecting an image on a display screen.

7. The projection device of claim 1 wherein:

said micromirrors further reflect said intermediate light flux transmitted along a plurality of intermediate light flux cross sections with some of said cross sections having different cross sectional shapes from a cross sectional shape of an optical pupil of an image projection lens along a projection light path for projecting an image on a display screen.

8. The projection device of claim 1 wherein:

said micromirrors further deflects to said ON direction to reflect a projection light along a projection optical axis with a projection light flux having a cross section substantially overlapped with an optical pupil of an image projection lens along a projection light path for projecting an image on a display screen; and

said micromirrors further reflect said intermediate light to transmit along a different optical axis angularly diverge from said projection optical path with said intermediate light flux having a cross section overlapped partially with an optical pupil of an image projection lens.

9. The projection device of claim 8 wherein:

the light source further comprises a laser light source, and an angle between the projection optical axis and said optical axis of said intermediate light is smaller than or equal to 12 degrees.

10. The projection device of claim 8 wherein:

the light source further comprises a laser light source, and an angle between the projection optical axis and said optical axis of said intermediate light is smaller than or equal to 8 degrees.

11. The projection device of claim 8 wherein:

the projection light path is substantially perpendicular to a surface of over said micromirror, and

said micromirrors further reflect said intermediate light to transmit along a different optical axis angularly between said projection optical axis and an optical path of an illumination light emitted from said light source to said spatial light modulator.

12. The projection device of claim 8 wherein:

said micromirrors further reflect an OFF light when deflected to said OFF direction wherein said OFF light transmitting along an optical axis angular outside of said projection optical axis and an optical path of an illumination light emitted from said light source to said spatial light modulator.

13. The projection device of claim 1 wherein:

said micromirrors further reflect said intermediate light comprising diffraction light fluxes generated from diffraction of illumination lights from the light source diffracted by edges of said micromirrors.

14. The projection device of claim 1 further comprising:

a light attenuator for attenuating said intermediate light reflected from said micromirrors to reduce an average light intensity generated by said intermediate light.

15. The projection device of claim 1 wherein:

the light source for emitting the illumination light further comprises a laser light source or an LED light source.

16. The projection device of claim 1 wherein:

the light source for emitting the illumination light includes sub-light sources for emitting a plurality of colors each transmitted in an optical axis along different direction.

17. The projection device of claim 1 wherein:

the light source for emitting of the illumination light includes sub-light sources for emitting a plurality of laser light sources or LED light sources wherein said controller further controls and adjusts an intensity of the light source, the a number of the sub-light sources for emitting light, or an interval and timing of light emission from each of said sub-light sources.

18. The projection device of claim 1 wherein:

the light source for emitting the illumination light includes sub-light sources for emitting a plurality of laser light sources or LED light sources wherein said controller further controls and adjusts an intensity of the light source, the a number of the sub-light sources for emitting light, or the an interval and timing of light emission from each of said sub-light sources to change the intensity distribution across the cross section of the projected light.

19. The projection device of claim 1 wherein:

the light source for emitting the illumination light further comprising a laser light source for emitting light having a plurality of wavelengths simultaneously for at least a period of time within a frame of a display period.

20. The projection device of claim 1 wherein:

the light source further comprises a plurality of sub-light sources emitting light beams along a plurality of illumination light paths, and reflected by the micromirrors of said spatial light modulator along different light paths.

21. The projection device of claim 1 wherein:

the controller controls the micromirrors to operate in said intermediate state by oscillating the micromirrors between said ON and OFF directions.

35. The projection device of claim 1 wherein:

said controller applies said input signal comprising a digital data to an electrode of each micromirror for moving the micromirror to operate in an intermediate state.

36. The projection device of claim 35 wherein:

said digital data further comprising non-binary data.

22. A projection device receiving a light from a light source through an illumination optics for projecting to a spatial light modulator having a plurality of micromirrors controlled to different deflection angles, said projection device further comprising:

a controller that receives and applies an input signal to control each of said micromirrors to deflect to a first deflection angle along an ON direction and a second deflection angle along an OFF direction and to operate in an intermediate state for reflecting an intermediate light having an intermediate intensity between light intensities reflected by said micromirrors in said ON and OFF directions wherein said micromirrors reflect said intermediate light having a non-uniform and/or asymmetrical intensity distribution across a cross section of an intermediate light flux from the micromirrors; and

an intermediate motion stopper for stopping said micromirrors at an intermediate deflection angle for reflecting said intermediate light with a part of a cross section of said intermediate light to an image projection lens.

23. The projection device of claim 22 further comprising:

at least two drivers for driving the micromirror; and

a second motion stopper for stopping the micromirror at another deflection angle different from the intermediate deflection angle.

24. A projection device receiving a light from a light source through an illumination optics for projecting to a spatial light modulator having a plurality of micromirrors controlled to different deflection angles, said projection device further comprising:

a controller that receives and applies an input signal to control each of said micromirrors to deflect to a first deflection angle along an ON direction substantially perpendicular to a surface across said micromirrors and a second deflection angle along an OFF direction and to operate in an intermediate state for reflecting an intermediate light having an intermediate intensity between light intensities reflected by said micromirrors in said ON and OFF directions wherein said micromirrors reflect said intermediate light having a non-uniform and/or asymmetrical intensity distribution across a cross section of an intermediate light flux from the micromirrors; and

an angle between an optical axis of the light emitted from the light source versus the ON direction perpendicular to said surface across said micromirrors is less than or equal to 12 degrees.

25. The projection device of claim 24 wherein:

the angle between the optical axis of the light and a normal to the deflectable spatial light modulating element is smaller than or equal to 8 degrees,

the angle between the optical axis of the light emitted from the light source versus the ON direction perpendicular to said surface across said micromirrors is less than or equal to 8 degrees.

26. A projection device receiving a light from a light source through an illumination optics for projecting to a spatial light modulator having a plurality of micromirrors controlled to to different deflection angles, said projection device further comprising:

a controller that receives and applies an input signal to control each of said micromirrors to deflect to a first deflection angle along an ON direction substantially perpendicular to a surface across said micromirrors and a second deflection angle along an OFF direction and to operate in an intermediate state for reflecting an intermediate light having an intermediate intensity between light intensities reflected by said micromirrors in said ON and OFF directions wherein said micromirrors reflect said intermediate light having a non-uniform and/or asymmetrical intensity distribution across a cross section of an intermediate light flux from the micromirrors; and

said micromirrors further reflect said intermediate light flux in a period within a display frame having a cross section overlapped partially with an optical pupil of an image projection lens along a projection light path for projecting an image on a display screen.

27. The projection device of claim 26 wherein:

said micromirrors further reflect said light flux in said OFF direction to a partial plane including the optical axis of the illumination light and the optical axis of the projection light path.

28. A projection device receiving a light from a light source through an illumination optics for projecting to a spatial light modulator having a plurality of micromirrors controlled to different deflection angles, said projection device further comprising:

a controller that receives and applies an input signal to control each of said micromirrors to deflect to a first deflection angle along an ON optical path and a second deflection angle along an OFF optical path and to operate in an intermediate state for reflecting an intermediate light having an intermediate intensity between light intensities reflected by said micromirrors in said ON and OFF directions wherein said micromirrors reflect said intermediate light having a non-uniform and/or asymmetrical intensity distribution across a cross section of an intermediate light flux from the micromirrors wherein said controller controls said micromirror to deflect to an intermediate optical path along an angular orientation between said ON optical path and said OFF optical path.

29. The projection device of claim 28 further comprising:

a light absorber disposed along said OFF optical path for absorbing an OFF light projected thereto.

30. The projection device of claim 28 wherein:

the intermediate light path lies between the OFF light path and a light path along an illumination light emitted from said light source to said spatial light modulator.

31. The projection device of claim 28 wherein:

the intermediate light path lies between the OFF light path and the ON light path.

32. The projection device of claim 28 wherein:

the light source further comprises a plurality of sub-light sources,

and the controller further controls intensities and timing for emitting light from the plurality of sub-light sources to corresponding to the micromirrors to operate in the intermediate state to control the intermediate intensity.

33. The projection device of claim 28 wherein:

the light source further comprises a plurality of sub-light sources, and the controller further controls intensities and timing for emitting light from the plurality of sub-light sources to corresponding to the micromirrors to operate in the intermediate state to control a distribution of the intermediate intensity transmitting along said intermediate light path.

34. The projection device of claim 28 wherein:

the cross section of a light flux projected along said ON light path overlapping with a cross section of a light flux projected along said intermediate light path, and the controller further controls the spatial light modulator to switch between the intermediate light path and the ON light path in a time sequential manner.