Spatial light modulator with sub-wavelength structure

• US 7,595,927 B2
• Filed: 06/29/2007
• Issued: 09/29/2009
• Est. Priority Date: 11/01/2003
• Status: Active Grant

• Current Assignee: Ignite USA (Ignite)
• Original Assignee: Olympus Corporation, Silicon Quest Kabushiki-Kaisha
• Inventors: Maeda, Yoshihiro, Ichikawa, Hirotoshi, Ishii, Fusao
• Primary Examiner(s): Spector; David N
• Application Number:
  US11/823,947
• Publication Number:
  US 20080002155A1
• Time in Patent Office: 823 Days
• Field of Search: 345/690, 359/290, 359/291, 359/292, 359/295
• US Class Current: 359/291
• CPC Class Codes: G03B 21/008 using micromirror devices
• CPC Class Codes: G03B 21/14 Details
• 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 9/3155 for controlling the light source light source control per se H05B35/00 – H05B47/00; control of an illumination source for displays in general G09G3/3406

Abstract

An image projection device receives a light emitted from a light source through an illumination optic for projecting to a spatial light modulator (SLM) having a plurality of deflectable micromirrors The micromirrors further formed with a sub-wavelength microstructure on a reflective surface of the micromirrors having a reflection guided mode resonant grating to take advantage of an ultra-fine processing technology available in recent years used in semiconductor manufacture and micro-machining to fabricate a sub-wavelength grating (SWG) having a pitch between the grating ridges that is smaller than the wavelength of light.

Claims

1. An image projection device receiving a light from a light source through an illumination optic for projecting to a spatial light modulator having a plurality of deflectable micromirrors wherein said micromirrors further comprising:

a sub-wavelength microstructure on a reflective surface of said micromirrors to reflect a specific wavelength in said light from the light source through a resonant scattering from said sub-wavelength microstructure.

2. The image projection device of claim 1 wherein:

said sub-wavelength microstructure further comprising a reflection guided mode resonant grating for reflecting said light of said specific wavelength.

3. The image projection device of claim 1 further comprising:

a semiconductor substrate supporting electrodes and deflectable hinges thereon wherein said hinges support said micromirrors and electric signals are applied on said electrodes for driving and deflecting said micromirrors supported on said hinges to different inclined angles.

4. The image projection device of claim 1 wherein:

said micromirrors further comprising at least two micromirrors different sub-wavelength structures for reflecting lights of two different wavelengths from at least two micromirrors.

5. The image projection device of claim 1 wherein:

said micromirrors further comprising at least two micromirrors having at least two different sub-wavelength structures for reflecting lights of at least two primary colors.

6. The image projection device of claim 1 wherein:

said micromirrors further comprising at least two micromirrors having at least two different sub-wavelength structures for reflecting lights of at least two secondary primary colors.

7. The image projection device of claim 1 wherein:

said micromirrors further comprising a plurality micromirrors having different sub-wavelength structures for reflecting lights substantially over an entire range of spectrum projected form a light source.

8. The image projection device of claim 1 wherein:

said micromirrors having a pitch extended between two adjacent mirrors having a length substantially between four to twelve micrometers (4 to 12 μ

m).

9. The image projection device of claim 1 further comprising:

a semiconductor substrate for supporting electrodes and deflectable hinges thereon wherein said deflectable hinges support said micromirrors and electric signals are applied on said electrodes for driving and deflecting said micromirrors to different inclined angles; and

a controller for generating said electric signals for inputting to said electrodes to control said micromirrors according to a pulse width modulation (PWM) mode.

10. The image projection device of claim 1 further comprising:

a semiconductor substrate for supporting electrodes and deflectable hinges thereon wherein said deflectable hinges support said micromirrors and electric signals are applied on said electrodes for driving and deflecting said micromirrors and said hinges wherein said micromirrors having a distance between adjacent micromirrors ranging substantially between four to twelve micrometers.

12. The image projection device of claim 10 wherein:

said light source further comprising a laser light source for projecting lights of at least two different wavelengths corresponding to at least two of said specific wavelength structures.

13. The image projection device of claim 10 wherein:

said light source further comprising a light-emitting diode (LED) light source for emitting a light of a specific wavelength.

15. The image projection device of claim 9 wherein:

said controller controlling said micromirrors to operate in said freely oscillation mode with a natural oscillation frequency as a function of an elasticity of said deflectable hinge to project a smaller amount of controllable light intensity than a fully-ON light intensity to display an image with higher levels of gray scales.

11. An image projection device receiving a light from a light source through an illumination optic for projecting to a spatial light modulator having a plurality of deflectable micromirrors wherein said deflectable micromirrors further comprising:

a sub-wavelength microstructure on a reflective surface of said micromirrors; and

said micromirrors each having a specific wavelength structure for selectively reflecting or transmitting a light of a selected wavelength substantially equal to one of a wavelengths projected from said light source.

14. An image projection device receiving a light from a light source through an illumination optic for projecting to a spatial light modulator (SLM) having a plurality of deflectable micromirrors each for displaying a pixel wherein said deflectable micromirrors further comprising:

a sub-wavelength microstructure on a reflective surface of said micromirrors; and

said micromirrors of said SLM each having a specific wavelength structure for selectively reflecting or transmitting a light of a selected wavelength substantially equal to one of a wavelengths projected from said light source.

16. An image projection device comprising mirror device having a plurality of deflectable micromirrors wherein:

at least two of said micromirrors having two different reflective surfaces of two different shapes or two different structures.

17. The image projection device of claim 16 wherein:

at least two of said micromirrors having said two different reflective surfaces comprising at least two reflective surfaces of two different optical characteristics.

18. The image projection device of claim 16 wherein:

at least two of said micromirrors having said two different reflective surfaces comprising at least two reflective surfaces of two different physical characteristics.