Parallel space light modulator

Abstract

To provide a 3D projector having two light modulators to modulate light from a single wide-bandwidth light source, without causing loss of light emitted to heat.SOLUTION: Optical splitters 110 and 120 (e.g., dichroic mirrors) are used to direct one set of wavelengths to one optical modulator 130 and the other set of wavelengths to the other optical modulator 140. As a result, spectral components rejected by one modulator are used to illuminate the other.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] 1. Technical Field The present invention relates to a projector, and more particularly to a 3D projector having two light modulators for modulating light from a single broadband light source such that a discarded light spectrum from one light modulator is used to illuminate the other light modulator.

Background Art

[0002] 2. Description of Related Art In wavelength multiplex displays, a projector uses a pair of spatial light modulators to project a specific combination of wavelengths (e.g., left-eye RGB spectrum and right-eye RGB spectrum) from a light source onto a screen. 3D glasses having complimentary dichroic filters in the lenses are worn by an observer who filters out one or the other set of three light wavelengths. In this way, a single projector can simultaneously display left and right stereoscopic images.

[0003] Dual projector 3D systems for generating different combinations of wavelengths using RGB laser illumination are known. Systems using polarization modulation are also known, but such systems function optimally only after the modulation phase since most glasses do not maintain polarization.

[0004] In other systems, combinations of two wavelengths can be created by filtering broadband light using a dichroic filter in front of a spatial light modulator. However, the problem with using broadband light to generate two visible spectra for wavelength multiplexed 3D is that filtering in front of the spatial light modulator results in loss of light that is dissipated as heat. SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0005] One aspect of the present invention is to provide a 3D projector having two light modulators for modulating light from a single broadband light source without loss of light dissipated as heat. In an embodiment, an optical splitter (e.g., dichroic) is used to split one combination of wavelengths to one light modulator and the other combination of wavelengths to the other light modulator. As a result, the spectrum discarded from one modulator is used to illuminate the other modulator. This can result in approximately twice the efficiency of prior art 3D projection systems since each light modulator modulates only the light that the other modulator has not modulated.

[0006] In some embodiments, both light modulators are disposed within a housing for receiving light from a common high etendue broadband light source. MEANS FOR SOLVING THE PROBLEM

[0007] The above aspect can be achieved by a projector including at least one broadband light source, a first optical splitter configured to receive broadband light from the at least one broadband light source, reflect a first combination of wavelengths of the broadband light, and transmit a remaining combination of wavelengths different from the first combination of wavelengths, a second optical splitter configured to receive the remaining combination of wavelengths of the broadband light from the first optical splitter, reflect a second combination of wavelengths of the remaining combination of wavelengths, and transmit a further remaining combination of wavelengths different from the first combination of wavelengths and the second combination of wavelengths, a first optical modulator for modulating the first combination of wavelengths of the broadband light, a second optical modulator for modulating the second combination of wavelengths of the broadband light, and a first projection optical system and a second projection optical system configured to project the first modulated light and the second modulated light, respectively.

[0008] In another aspect, there is provided a projector including at least one broadband light source, a first optical splitter configured to receive broadband light from the at least one broadband light source, reflect a first combination of wavelengths of the broadband light, and transmit a remaining combination of wavelengths different from the first combination of wavelengths, a second optical splitter configured to receive the remaining combination of wavelengths of the broadband light from the first optical splitter, reflect a second combination of wavelengths of the remaining combination of wavelengths, and transmit a further remaining combination of wavelengths different from the first combination of wavelengths and the second combination of wavelengths, a first optical modulator for modulating the first combination of wavelengths of the broadband light, a second optical modulator for modulating the second combination of wavelengths of the broadband light, and a first projection optical system and a second projection optical system configured to project the first modulated light and the second modulated light, respectively.

[0009] These, together with other aspects and advantages that will become apparent later, are set forth more fully hereinafter with reference to the accompanying drawings, which form a part of this specification, and in the detailed description of the configurations and operations as claimed, where like numerals refer to like parts throughout.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0011] Referring to FIG. 1, a broadband light source 100 provides light to a parallel pair of light splitters 110, 120 and light modulators 130, 140 within a housing 150. The modulated light is transmitted to projection optics 160, 170 outside the housing 150.

[0012] In embodiments, multiple broadband light sources can be used, and the broadband light source 100 can be a laser or a lamp, or multiple lasers or lamps. In embodiments, the light splitters 110, 120 can be dichroic (two-color) coatings, as is known in the art. The light modulators 130, 140 can be DMD, LCOS, DLP, transmissive LCD, diffraction, or other suitable light modulators, as is known in the art. In some embodiments, the broadband light source 100 can be disposed within the housing 150, but since a laser light source typically has all light from one etendue and cannot be included within the housing 150 due to, for example, increased etendue and / or light scattering when the laser light source is remote, it is not necessary to dispose it within the housing.

[0013] During operation, the broadband light source 100 projects white light onto the first optical splitter 110. The first optical splitter 110 transmits all except a first combination of wavelengths of the broadband light (e.g., RGB1) to the second optical splitter 120, and reflects the first combination of wavelengths to the first optical modulator 130 and the projection optical system 160. The second optical splitter 120 receives the remaining light from the splitter 110 and transmits all except a second combination of wavelengths (e.g., RGB2, a combination of the remaining wavelengths different from the first combination of wavelengths) that is reflected to the second optical modulator 140 and the projection optical system 170. The remaining light transmitted by the second optical splitter 120 can be collected by the light dump 180.

[0014] The first and second optical modulators 130, 140 are controlled in tandem so as to form a 3D image. By illuminating the first and second optical modulators 130, 140 from the same light source, the broadband light source 100, both optical modulators have the same étendue.

[0015] By sharing light from one or more common light sources such as the broadband light source 100 and operating the two optical modulators 130, 140 in parallel within a single housing 150, the broadband light can be split into two different spectra and modulated independently by each of the modulators 130, 140.

[0016] FIG. 2 shows an exemplary method of 3D projection, which includes generating broadband light 200 according to one embodiment, splitting broadband light 210 to reflect a first combination of wavelengths (RGB1) of the broadband light, and transmitting a remaining combination of wavelengths different from the first combination of wavelengths. At 220, the remaining combination of wavelengths of the broadband light is split to reflect a second combination of wavelengths (RGB2) among the remaining combinations of wavelengths, and transmits a further remaining combination of wavelengths different from the first combination of wavelengths and the second combination of wavelengths, which can optionally be collected in an optical dump. At 230, the first combination of wavelengths of the broadband light is modulated. At 240, the second combination of wavelengths of the broadband light is modulated. At 250, the first modulated light is projected, and at 260, the second modulated light is projected, and the first modulated light and the second modulated light are projected in parallel to form a three-dimensional image.

[0017] Many features and advantages of the invention will be apparent from the detailed description, and thus, it is intended that the appended claims cover all such features and advantages of the invention that fall within the true spirit and scope of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be used that fall within the scope of the invention.

Claims

1. At least one broadband light source, a first optical splitter configured to receive broadband light from the at least one broadband light source, reflect a first combination of wavelengths of the broadband light, and transmit the remaining combination of wavelengths different from the first combination of wavelengths; a second optical splitter configured to receive the remaining combination of wavelengths of the broadband light from the first optical splitter, reflect a second combination of wavelengths of the remaining combination of wavelengths, and transmit a further remaining combination of wavelengths different from the first combination of wavelengths and the second combination of wavelengths; a first optical modulator for modulating the first combination of wavelengths of the broadband light; a second optical modulator for modulating the second combination of wavelengths of the broadband light; a first projection optical system; a second projection optical system, and comprising: The first projection optical system and the second projection optical system are configured to project the first modulated light and the second modulated light respectively, a projector.

2. The projector according to claim 1, wherein the first optical modulator and the second optical modulator each comprise a digital micromirror device (DMD).

3. The projector according to claim 1, wherein the first optical modulator and the second optical modulator each comprise a liquid crystal on silicon (LCOS) device.

4. The projector according to claim 1, wherein the first optical modulator and the second optical modulator each comprise a transmissive liquid crystal display device.

5. The projector according to claim 1, wherein the first optical modulator and the second optical modulator each comprise a diffractive optical modulator.

6. The projector according to claim 1, wherein the first optical splitter comprises a first dichroic configured to receive the broadband light, reflect the first combination of wavelengths towards the first optical modulator, and transmit the remaining combination of wavelengths to the second optical splitter.

7. The projector according to claim 1, wherein the second optical splitter comprises a second dichroic configured to receive the remaining combination of wavelengths, reflect the second combination of wavelengths towards the second optical modulator, and transmit the further remaining combination of wavelengths different from the second combination of wavelengths.

8. The combination of the first wavelengths includes a first set of red, green, and blue wavelengths, The combination of the second wavelengths includes a second set of red, green, and blue wavelengths, the projector according to claim 1. **Claim 9** The first projection optical system and the second projection optical system are configured to project the first modulated light and the second modulated light in parallel, respectively, the projector according to claim 1. **Claim 10** The at least one broadband light source is a single broadband light source, the projector according to claim 1. **Claim 11** The at least one broadband light source is a plurality of broadband light sources, the projector according to claim 1. **Claim 12** The at least one broadband light source is external to the projector, The projector further includes one or more apertures and an optical system for receiving the broadband light from the broadband light source, the projector according to claim 1. **Claim 13** The first modulated light and the second modulated light projected by the first projection optical system and the second projection optical system form a three-dimensional image, the projector according to claim 1. **Claim 14** The projector further includes a light dump for collecting the combination of the further remaining wavelengths transmitted by the second optical splitter, the projector according to claim 1. **Claim 15** The first optical splitter, the second optical splitter, the first optical modulator, and the second optical modulator are arranged within a housing, the projector according to claim 1. **Claim 16** generating broadband light; splitting the broadband light so as to reflect a first combination of wavelengths of the broadband light and transmitting the remaining combination of wavelengths different from the first combination of wavelengths; splitting the remaining combination of wavelengths of the broadband light so as to reflect a second combination of wavelengths among the remaining combination of wavelengths and transmitting a further remaining combination of wavelengths different from the first combination of wavelengths and the second combination of wavelengths; modulating the first combination of wavelengths of the broadband light; modulating the second combination of wavelengths of the broadband light; optically projecting the first modulated light; optically projecting the second modulated light, and including The 3D projection method, wherein the first modulated light and the second modulated light are projected in parallel to form a three-dimensional image. **Claim 17** The combination of the first wavelengths includes a first set of wavelengths of red, green, and blue, The method according to claim 16, wherein the combination of the second wavelengths includes a second set of wavelengths of red, green, and blue.

Images