JP7518492B2 - Spatial light modulator image display projector apparatus with solid-state illumination source - Patents.com - Google Patents

Description

This application relates generally to image display projector apparatus and methods, and more particularly to spatial light modulator (SLM) image display projection with solid-state illumination (SSI) light sources.

An exemplary SLM projector is described in U.S. Patent No. US 9,195,123, which is incorporated herein by reference. This exemplary system uses a blue laser as a direct source of blue light and as an indirect source of other colored light by exciting phosphors with the blue light from the blue laser.

Other arrangements for producing color sequences using the color wheel and relative motion of the input light beam are also possible. U.S. Patent No. US 8,496,352, which is incorporated herein by reference, describes an exemplary color wheel having concentric annular tracks or rings of phosphor that emit respective colors at different radially spaced locations.
U.S. Patent No. US9,195,123 U.S. Patent No. US8,496,352

In some projectors equipped with a Texas Instruments DLP® Digital Micromirror Device (DMD), red, green, and blue light are combined in the light path.

In the illustrated example, the projector includes a light source for generating a first light of a first color. The projector also includes a phosphor for selectively receiving the first light and for generating a second light of a second color in response to the first light. The projector also includes a dichroic mirror for passing a portion of the second light to generate a third light of a third color. The dichroic mirror reflects a portion of the second light as a fourth light of a fourth color.

1 illustrates an example projection system and an example light source. 1 illustrates an example projection system and an example light source.

4 illustrates another exemplary light source. 4 illustrates another exemplary light source.

1 illustrates an example architecture.

1 illustrates an example two-chip architecture.

Illustrates phosphor emission spectra. Illustrating phosphor emission spectra

1 illustrates an exemplary configuration of a phosphor wheel.

2 illustrates another example architecture.

2 illustrates another example architecture.

9 illustrates a modification of the example architecture of FIG. 8.

1 illustrates an exemplary arrangement having an infrared (IR) light source.

1 illustrates another exemplary arrangement having an IR light source.

1 illustrates another exemplary arrangement having an IR light source.

2 is another example architecture.

1 is a diagram of an example modulation module having a three-part total internal reflection (TIR) prism and a digital micromirror device (DMD).

1 is a diagram of another example modulation module having a two-section inverse TIR (RTIR) prism and a DMD.

1 is a diagram of another example modulation module having a four-section TIR prism and a DMD.

FIG. 2 is a diagram of an example combiner cube with two spatial light modulators (SLMs).

FIG. 2 is a diagram of an example Philips combiner with two SLMs.

FIG. 1 is a diagram of an example two-chip architecture having a three-part TIR with combiner cube. FIG. 1 is a diagram of an example two-chip architecture having a three-part TIR with combiner cube. FIG. 1 is a diagram of an example two-chip architecture having a three-part TIR with combiner cube.

FIG. 2 is a diagram of another example architecture. FIG. 2 is a diagram of another example architecture. FIG. 2 is a diagram of another example architecture.

FIG. 2 is a diagram of another example architecture.

1 is a flow chart of an example method.

10 is a flow chart of another example method.

In the drawings, corresponding numbers and symbols generally refer to corresponding parts unless otherwise indicated. The drawings are not necessarily drawn to scale.

In this description, the term "coupled" may include connections made with intervening elements, and additional elements and various connections may exist between any elements that are "coupled."

An exemplary projector arrangement includes a spatial light modulator (SLM), such as a Texas Instruments DLP® Digital Micromirror Device (DMD). The mirrors of the SLM are individually set using a pulse width modulated (PWM) intensity gray scale with the settings synchronized to each time segment for the illumination of the mirror with each sequentially generated color. A "two-chip" architecture has two DMDs. Thus, the two-chip architecture directs light onto both DMDs, so that one color of light is modulated by the first DMD and two other colors of light are modulated by the second DMD. The two-chip architecture achieves high efficiency using light emitting laser diodes, laser/phosphor and laser architectures. An exemplary two-chip architecture is described below. Another example described herein uses only high power yellow and blue laser diodes, with one filter for both combination and top-side pumping.

1A and 1B (collectively "FIG. 1") show an example projection system 100 and an example light source. FIG. 1A shows an example light source using a blue laser and a yellow phosphor. An example yellow phosphor is described in Denault et al., "Efficient and Stable Laser-Driven White Lighting," AIP Advances 3, 072107 (2013), which is incorporated by reference herein. The use of a yellow light source provides many advantages, including: (a) highly efficient phosphor conversion, for example for use in a white illumination source; (b) blue laser diode backlight for increased efficiency; (c) the ability to use top-side pumping to increase light output; (d) the use of only three laser diodes, the same number as in a red, green, and blue (RGB) implementation, and therefore no increased cost compared to an RGB implementation; and (e) various options for implementation, such as a rotating wheel implementation, using a mixture of yellow and/or green phosphors. In the exemplary arrangement of Figures 1A and 1B, the phosphor is fixed rather than mounted on a wheel.
Denault, et al. “Efficient and Stable Laser-driven White Lighting” AIP Advances 3,072107 (2013)

For use in automotive, stage lighting, and general lighting, laser diode vendors have developed white laser diodes. These laser diodes convert a blue wavelength source to yellow light by using blue light to stimulate a yellow phosphor. The remaining blue light is added to the light emitted by the yellow phosphor to create a white light source. The laser diode can be adapted to produce only yellow light by changing the phosphor parameters. This yellow laser diode can be used with a two-chip architecture to improve brightness.

As will be further described below, yellow light 102 and blue light 104 from the light source are used to create sequential color drive for the two-chip architecture. In the example of FIG. 1A, blue light 106 from a laser diode 108 reflects off a long-pass filter 110 and hits a phosphor 112. As will be further described below, the phosphor 112 modulates the light into a broadband spectrum of yellow light 102. A blue laser diode 114 also stimulates the phosphor 112. A lens (not shown) focuses the yellow light 102 that passes through the long-pass filter 110. Here, the yellow light 102 alternates with blue light 104 from a laser diode 116. The two-chip architecture, which will be described below, separates the yellow light 102 into red and green light components. The yellow phosphor has a spectrum that is chosen to produce the desired green and red (when split), or any other desired color gamut. An even wider color gamut can be created by adding notch filters to the filter stack. The laser diode 108 pumps the top side of the phosphor 112 to increase its light output. This can provide an additional 10% to 20% of the light output from the yellow phosphor.

Blue light 104 passes through dichroic mirror 153 as light 164. In this example, dichroic mirror 153 reflects green light. In another example, dichroic mirror 153 may reflect blue light 104 while passing red light. When blue light 104 is provided from (e.g., generated by) laser diode 116, light 164 is blue and passes through prism 166 to illuminate spatial light modulator 168. Modulated light 172 passes through prism 170 to combiner 174, which includes dichroic layer 176. In this example, dichroic layer 176 reflects red and blue light and passes green light. Light 172 reflects off dichroic layer 176 as light 180 to projection optics 178.

The yellow light 102 is separated by the dichroic mirror 153. The red component of the yellow light 102 passes through the dichroic mirror 153 and follows the path described above for the blue light 104. The green portion of the yellow light 102 is reflected by the dichroic mirror 153 as light 154. The light 154 passes through the prism 156 and illuminates the spatial light modulator 158. The modulated light 162 passes through the prism 160 and the dichroic layer 176 and combines with the light 172 to provide light 180. Thus, in the light 180, the red light is modulated by the spatial light modulator 168 and the green light is modulated by the spatial light modulator 158. The light 180 travels to the projection optics 178. Thus, by alternately providing yellow light 102 and blue light 104 to the two-chip architecture using SLMs 158, 168, and splitting yellow light 102 into red and green components using dichroic mirror 153, the light source provides red, green, and blue light for driving the two-chip system. FIG. 1B shows an alternative exemplary light source 150 comprising a yellow phosphor 152 with a top-side pump provided (e.g., generated) by laser diode 108. With light source 150, yellow light 102 is provided by activating laser diode 108, and blue light 104 is provided by activating laser diode 116.

2A and 2B (collectively "FIG. 2") show another exemplary light source. Where the reference numbers of elements in FIG. 2 correspond to the reference numbers of elements in FIG. 1, these elements in FIG. 2 perform functions similar to the corresponding elements in FIG. 1. For example, yellow light 202, blue light 204, blue light 206, laser diode 208, long wavelength pass filter 210, and laser diode 216 in FIG. 2 correspond to yellow light 102, blue light 104, blue light 106, laser diode 108, long wavelength pass filter 110, and laser diode 116 in FIG. 1, respectively. FIG. 2A shows an exemplary light source 200 having a fixed yellow static phosphor 252 with bottom and top side pumps. Laser diode 208 provides top side light and laser diode 254 provides remote bottom side light. Yellow light is provided by activating laser diodes 208 and 254. Blue light is provided by activating laser diode 216.

2B shows an example light source 250 having a transmissive phosphor wheel 256 with a laser diode 254 pump at the bottom (orientation in FIG. 2B) and a laser diode 208 pump at the top (orientation in FIG. 2B). A short wavelength pass filter 258 is placed behind the phosphor wheel 256. The short wavelength pass filter 258 allows light from the laser diode 254 to pass to the phosphor wheel 256, but reflects the yellow light created by the interaction of the light from the laser diode 254 (and laser diode 208). By activating the laser diodes 208 and 254, yellow light is provided. By activating the laser diode 216, blue light is provided. In at least one example, a green (or a combination of green and yellow) phosphor can be used in the transmissive phosphor wheel. The illumination in the examples of Figures 1 and 2 illuminates a two-chip architecture, such as the two-chip architecture shown in Figure 1A and Figures 3-21 as described below.

Some of the example imaging system designs for DMD SLMs in this application use laser diode and laser/phosphor light source illumination. Laser/phosphor light sources offer some efficiency advantages over traditional light source based systems. Also, the laser spot size on the phosphor can be reduced to best match the etendue of the DMD in the system. However, in laser/phosphor based systems, it may be necessary to filter the color emitted by the phosphor to achieve the desired color point. One example of such filtering is to use a yellow emitting phosphor and filter the yellow emitted by such a phosphor to achieve the desired red color. Another example is to filter the green phosphor emission to achieve the desired green point. In each of these examples, the full spectrum of light (produced by the phosphor) is filtered to remove the unwanted portion of the spectrum.

The number of lasers illuminating the phosphor is related to the lumen output of the projector. Adding lasers results in higher lumens, but at the cost of additional power. Also, the use of additional lasers may cause the phosphor to reduce its light generating efficiency (e.g., lumens per input watt), and the additional number of lasers increases the cost of the system. A multi-chip system architecture may reduce or eliminate some of the problems that arise from using a laser/phosphor-based light source in a single chip architecture. An example of a full-color projection display system using two DMD light modulators is described in U.S. Patent No. US 5,612,753, which is incorporated herein by reference.
U.S. Patent No. US 5,612,753

Figure 3 of U.S. Patent No. US 5,612,753 illustrates a two-modulator projector using a white light illumination source, in which white light (e.g., from a metal halide arc lamp) passes through color filter segments of a rotating color wheel. Each sequential color light emitted by the color wheel is relayed through a color separation prism, which passes the dominant first color to a first DMD modulator and the other second color to a second DMD modulator. The color combination prism cooperates with a total internal reflection prism (TIR prism) to recombine the reflected individual DMD-modulated lights for imaging through a single projection lens. In this system, the color wheel always passes one of the primary colors and alternates between the other two. The first DMD handles the modulation of red (the dominant color) and the second DMD handles the time-sequential modulation of green and blue (the other colors).

3-13 illustrate examples of illumination in an architecture with two digital micromirror (DMD) chips, using a laser light source and phosphor radiation instead of a white light source, and using a two-prism cube to combine the individually modulated colors. U.S. Patent Application Publication No. US 2014/0347634, published Nov. 27, 2014, which is incorporated herein by reference, discloses projector architectures with phosphor and laser light sources to illuminate two-chip and three-chip SLM architectures.
U.S. Patent Application Publication No. US2014/0347634

3 illustrates an example architecture 300. Blue laser light B1 from a first light source 322 travels through a lens 325, a first angled filter 324, and a lens 328 onto the front side of a phosphor wheel 309. The phosphor wheel 309 has a circular segment coated with a yellow-emitting phosphor 318 (see label A in FIG. 3). For example, the light source can be a laser diode light source. The yellow segment is continuous, and the yellow segment exposes the incident laser light over one revolution of the wheel 309, which rotates at least once per frame. The yellow light Y travels back through a lens 328 to a first angled filter 324, which reflects at least the red component R as a dominant color through a lens 331, a light tunnel 333, and a lens 334 to a first total internal reflection prism (TIR prism) optical element 326. The first TIR prism optical element 326 provides light R to the first DMD 332 for modulation. Blue laser light B2 from the second blue laser light source 310 passes through an angled polarizing filter 312, a quarter wave plate (QWP) 315, and a lens 337 onto the back side of the phosphor wheel 309. The back side of the wheel 309 has a 180° segment coated with green emitting phosphor 314 (see label B in FIG. 3 ), which emits green light G in response to the blue incident laser light B2 during just over 50% of the frame, and reflects the blue incident light B2 off a reflective (e.g., aluminum) reflector 317 for the remainder of the frame time. The sequentially emitted green and blue colors travel back through a quarter wave plate 315 to an angled polarizing filter 312, which reflects the polarization shifted blue and green light through a lens 338, a light tunnel 340, a lens 342, and a mirror 344 to a second TIR prism optical element 316, which provides the green and blue light to a second DMD 330 for common time sequential modulation. A two-prism cube combiner 306 combines the modulated dominant color (R) and other color (G and B2) light into a modulated composite beam 336 for projection of the formed image onto a target surface. The relative arcuate extent of the green phosphor segment 314 and the laser on/off times can be selected to vary the respective color modulation times to set the desired color (white) point.

4 illustrates an example two-chip architecture 400 having a single laser light source 422 and a monochromatic phosphor wheel 409. The monochromatic phosphor wheel 409 has a circular arrangement of an arcuate segment of yellow phosphor 418, an arcuate segment of green-emitting phosphor 414, and an arcuate segment of a surface 417 that reflects blue (denoted A in FIG. 4). Each of these arcuate segments can have a different length. In this example, red and green combine for yellow, so that for the time that blue laser light B2 is incident on the yellow-emitting phosphor segment or the green-emitting phosphor segment, the yellow-emitting phosphor segment or the green-emitting phosphor segment emits green, and for the time that the laser light is incident on the yellow phosphor segment, the yellow phosphor segment emits red. The blue laser light B2 is directed onto the phosphor wheel 409 (by transmission through the first angled polarizing filter 424, the quarter wave plate 415, and the lens 434) and directed to one spatial light modulator. The red/green or green light (which is emitted by excitation of the corresponding yellow phosphor 418 or green phosphor segment 414) is reflected back through the lens 434 and the quarter wave plate 415, off the first angled polarizing filter 424, and passes through the lens 436, the light tunnel 438, and the lens 440. The red light is transmitted through the second filter 425 to the first TIR prism 416 and the first DMD 430 for separate modulation. The second filter 425 reflects the green light to the second TIR prism 426 and the second DMD 432. The first and second filters 424, 425 reflect the phase-shifted blue light (reflected off the reflective surface 417 of the wheel 409) to a second TIR prism 426 for time-sequential modulation with green light by a second DMD 432. A two-prism cube combiner 406 combines the time-sequentially modulated colors for projection of an image for visual integration of the continuous red and time-sequential green/blue modulation during a frame display time on a display screen (not shown).

Views B-E of FIG. 4 illustrate some of the many other segment configurations (labeled 409b-e, respectively) that can be used for the phosphor wheel 409 in the arrangement of FIG. 4. Views B and C illustrate wheels 409b and 409c that have yellow phosphor 418 arranged in a circular ring band on the reflective surface of the wheel. The yellow phosphor 418 segment in view B occupies the position of both the yellow phosphor 418 and green phosphor segments 414 in view A and has a continuous ring shape that is interrupted by two approximately 30° arcuate segments of blue laser light reflective surface 417 at diametrically opposed locations on the ring. View C is similar to view B, except that only one blue light reflective surface 417 interrupts the yellow phosphor 418. Neither view B nor view C configuration has a green segment. For example, the phosphor composition of the yellow segment may provide an emission spectrum similar to that illustrated in FIG. 5A, where the yellow phosphor emits both red and green light when excited by incident blue laser light. Dichroic filters 425 are appropriately selected to filter the emitted light to direct the desired red and green components R and G to respective respective first and second DMDs 430, 432 for modulation.

Views D and E of FIG. 4 show wheels 409d and 409e having green-emitting phosphor 414 segments arranged in a circular ring band similar to that shown for the yellow phosphor 418 segment in views B and C. As described above, one or more arcuate segments of the blue light reflecting surface 417 similarly interrupt the green phosphor segment ring. The wheels of views D and E do not have a yellow phosphor segment. The phosphor composition of the green segment is selected to provide both red and green emission, such as the example emission spectrum illustrated in FIG. 5B. A dichroic filter 425 may filter the emitted light to isolate and direct the desired red and green components R and G for modulation by the respective first and second DMDs 430, 432. The different heights of response for the yellow and green phosphors 418, 414 (as shown by the spectra shown in Figures 5A and 5B) can be balanced by applying different attenuation (by adjusting the on/off timing of the mirrors) in the first and second DMDs 430, 432, respectively.

Figure 6 illustrates an example configuration of wheel 609 using a coating of yellow 618 and green 614 phosphors (which have emission spectra similar to those shown in Figures 5A-B) on the light-reflective surface of an aluminum wheel. The yellow 618 and green 614 phosphors each occupy a 150° portion of a circular band, with an uncoated area 617 occupying the remaining 60°. Thus, the light-reflective surface is exposed in the uncoated area 617. The wheel 609 can be rotated an integer number of revolutions or greater per available frame imaging time.

7 illustrates another example architecture 700. In this example, phosphor wheel 709 has blue light transmitting slits 719 (denoted A in FIG. 7) instead of all or part of blue light reflecting surface 417 (FIG. 4) that interrupts the phosphor ring segments. In this example, the red light phosphor emission R and the green light phosphor emission G can be the same as described with respect to the example of FIG. 4. However, wheel 709 transmits at least a portion of the blue laser light B2 on separate paths through lens 734, reflecting off mirror 736, reflecting off mirror 738, through lens 740, reflecting off filter 727, through lens 742, through light tunnel 744, through lens 746, reflecting off filter 725, through TIR prism 726, and to the second DMD 732. In this example architecture 700, as the wheel rotates, at least a portion of the blue laser light B2 emitted by the laser light source 722 passes through a light-transmitting slit 719 of the phosphor wheel 709. For example, the light-transmitting slit 719 can be one or more arc-shaped slits or blue light-transmitting windows added to one or more locations of the blue light reflecting surface 417 described above in the example of FIG. 4. As the light from the laser light source 722 passes through the filter 724, through the lens 748, and to the light-transmitting slit 719 of the rotating wheel 709, at least a portion of that light can pass through the wheel and be directed (e.g., by reflective optics, etc.) along a separate path (which can include an additional filter 727 and some common elements with red and/or green emitted light relay paths) to the second DMD 732 for timing sequential modulation with green light. Optionally, the transmissive slit 719 may be integrated with the phosphor segment portion, so that the green and blue lights may be modulated together during at least a portion of the frame modulation cycle. As in the example of FIG. 4, the filter 725 passes the red light through the TIR prism 716 to the DMD 730, and the combiner 706 combines the modulated light from the DMD 730 and the DMD 732 to provide a combined light for an image on a target surface. Views B-E in FIG. 7 illustrate some of the other configurations 709b-e that may be used for the phosphor wheel 709, which include configurations of phosphor segments 714 and 718 corresponding to the configurations of phosphor segments 414, 418 shown in views B-E in FIG. 4. However, the blue light transmissive slit 719 is placed in the position shown in FIG. 4 for the blue light reflecting surface 417 (FIG. 4). To diffuse the transmitted blue light, the slot may include a diffusing element (not shown).

FIG. 8 illustrates another example architecture 800. In this example, a transmissive phosphor wheel 809 produces all colors. Also in this example, the wheel 809 can be a light transmissive material, either the entire wheel or at least a portion of the wheel. The phosphor material is on one surface of the wheel 809 and is excited by laser light directed to the opposite surface of the wheel. For example, the wheel 809 can include a light transmissive band having a first angle yellow light segment 818 covered by a yellow light producing phosphor to provide blue laser light transmission, a second angle green light segment 814 covered by a green light producing phosphor, and one or more third angle range uncoated segments 821 (label A in FIG. 8 ). As the wheel 809 rotates, blue laser light B2 (directed from laser light source 822 to the uncovered backside) may pass through lens 836 and wheel 809 and strike either the yellow phosphor segment 818 or the green phosphor segment 814, or may pass through the uncovered segment 821. Light striking the yellow or green phosphor emits red and green light, with the spectrum as illustrated in Figures 5A and 5B. The red light emitted by the phosphor passes through lens 838, lens 840, light tunnel 842, lens 844, and filter 825 to the first TIR prism 816. The first TIR prism 816 provides the red light to the DMD 830 for monochromatic modulation. The green light emitted by the phosphor and the blue light directly transmitted by the light source pass through lens 838, lens 840, light tunnel 842, and lens 844, reflect off filter 825, and to a second TIR prism 826. The second TIR prism 826 provides the green or blue light to DMD 832 for time-series modulation. A combiner 806 combines the modulated light from DMD 830 and DMD 832. Wheel 809 may contain both a filter and a diffuser element 835. Other example wheel configurations 809b-e are shown in views B-E of FIG.

9 illustrates a variation 900 of the example architecture 800 of FIG. 8 that uses a single filter to separate and combine colors. In this example, a light source 922 with a phosphor wheel 909 generates red, green, and blue colors through lenses 940 and 942, and from the phosphor wheel 909 through lenses 934, light tunnel 936, lens 938, TIR prism structure 916, and color separation prism structure 906 through the same path to DMDs 930, 932. The TIR prism structure 916 directs the light into the color separation prism structure 906 at the appropriate angle, so that (a) the red light is directed to the first DMD 930 at one exit face by reflection of a centrally placed angled dichroic filter 927 (f1), and (b) the green and blue light is directed to the second DMD 932 at another exit face by transmission through the same dichroic filter 927. The modulated beam returns along similar reflection and transmission paths and through the same TIR prism structure 916 to the projection lens (not shown) for display of a composite color image. As mentioned above, the red and green light can be produced by green and yellow phosphors 914, 918 having emission spectra similar to those shown in Figures 5A and 5B. The same principles can be applied to reflective phosphor wheel arrangements as described above.

10-12 illustrate example arrangements 1000, 1100, 1200 in which an infrared (IR) light source is introduced into a projection system. As shown in FIG. 10, the IR light is introduced by a laser light source 1010 followed by at least a portion of a relay optical system for modulation in a common and/or time-sequential manner with one or more other colors. The light source 1022 and phosphor 1018 generate red light, which passes through lens 1027, reflects off filter 1024, and travels via lens 1031, light tunnel 1033, lens 1034, filter 1025, and TIR prism 1016 to the SLM 1030. The light source 1022 and phosphor 1018 also generate green light, which passes through lens 1027, reflects off filter 1024, passes through lens 1031, light tunnel 1033, and lens 1034, reflects off filter 1025, and passes through TIR prism 1026 to the SLM 1032. The light source 1022 generates blue light by passing light through the phosphor wheel 1009 and lens 1036, which reflects off mirrors 1038, 1040, and 1042, passes through filter 1024, lens 1031, light tunnel 1033, lens 1034, reflects off filter 1025, and passes through TIR prism 1026 to the SLM 1032. Combiner 1006 combines the modulated light from SLMs 1030 and 1032, which is transmitted to projection optics (not shown).

In FIG. 11, an IR laser source 1110 introduces IR light in the direction of the light path generated by the phosphor wheel at a blue input laser light transmission filter 1124 located between the blue laser source 1122 and the phosphor wheel 1109. In FIG. 12, an IR laser source 1210 introduces IR light in the direction of the light path generated by the phosphor wheel at a blue input laser light transmission filter 1224 located between the blue laser source 1222 and the phosphor wheel 1209. In one example arrangement 1100, the light source 1122 and phosphors 1114 and 1118 generate red light, which passes through lens 1127, reflects off filter 1124, and travels through lens 1131, light tunnel 1133, lens 1134, filter 1125, and TIR prism 1116 to the SLM 1130. The light source 1122 and phosphors 1114 and 1118 also generate green light, which passes through lens 1127, reflects off filter 1124, passes through lens 1131, light tunnel 1133, and lens 1134, reflects off filter 1125, and passes through TIR prism 1126 to SLM 1132. The light source 1122 generates blue light, which reflects off phosphor wheel 1109, passes through lens 1127, reflects off filter 1124, passes through lens 1131, light tunnel 1133, and lens 1134, reflects off filter 1125, and passes through TIR prism 1126 to SLM 1132. Combiner 1106 combines the modulated light from SLMs 1130 and 1132, which passes to the projection optics (not shown).

In the exemplary arrangement 1200, the light source 1222 generates red, green, and blue light in conjunction with the phosphor wheel 1209. The light source 1222 generates blue light that travels through a polarizing filter 1224, a quarter wave plate 1225, and a lens 1228 to the phosphor wheel 1209. The colored light from the phosphor (or the reflection of the phosphor wheel 1209) passes through the lens 1228 and the quarter wave plate 1225, reflects off the polarizing filter 1224, through the lens 1230, reflects off the mirror 1232, travels through the lens 1234 and the color wheel (which is integrated into the phosphor wheel 1209) to the integration tunnel 1236. From the integration tunnel 1236, the light travels to modulation and projection optics (not shown).

For example, the introduced IR light may be useful in simulation situations requiring IR source imaging capabilities. Also, a red laser may be added for red enhancement in some applications. The same principles are applicable to the introduction of other light, for example in the ultraviolet (UV) or other non-visible regions of the electromagnetic spectrum.

The modulation or projection is not limited to the red, green, and blue primary colors in any of the examples described herein, and the same principles are readily applicable to other choices of primary or secondary colors.

An example implementation of the two-chip architecture has a single bank of lasers to create red, green, and blue light. In such an arrangement, the lasers create a phosphor light output that is split into red and green components. During the blue time, the blue light passes to the first (or second) DMD, during which time the mirrors of the second DMD are in an off state. Efficiency is improved since all light is generated by a single bank of lasers.

Figure 13 shows one suitable architecture 1300, such as the example architecture 700 described above with reference to Figure 7. This system design uses a single laser bank as the light source 1322. Light produced by phosphor 1314 or 1318 (or reflected off phosphor wheel 1309) travels through lens 1327 to a first filter 1324. The light source 1322 and phosphor 1314 generate red light, which passes through lens 1327, reflects off filter 1324, and travels through lens 1331, light tunnel 1333, lens 1334, filter 1325, and TIR prism 1316 to the SLM 1330. Light source 1322 and phosphor 1314 also generate green light, which passes through lens 1327 , reflects off filter 1324 , passes through lens 1331 , light tunnel 1333 , and lens 1334 , reflects off filter 1325 , and travels through TIR prism 1326 to SLM 1332 . Light source 1322 generates blue light, which passes through lens 1323, phosphor wheel 1309, and lens 1336, reflects off mirror 1338, through lens 1339, reflects off mirror 1340, through lens 1341, reflects off mirror 1342, through lens 1343, filter 1324, lens 1331, light tunnel 1333, and lens 1334, reflects off filter 1325, and passes through TIR prism 1326 to SLM 1332. In this example, the red light is split off to the first SLM 1330 and the green light passes to the second SLM 1332. When blue light is present, the blue light is sent to the second SLM 1332. (Note that in an alternative arrangement, SLM 1330 could also receive blue light by filter modification.) SLMs 1330 and 1332 modulate the two light paths separately. Color cube combiner 1306 recombines the "on" state light. In architecture 1300 shown in FIG. 13, filter 1325 passes red light, but could also be made to reflect red light by filter modification. A similar arrangement is applicable to the green/blue channel. Thus, filter 1325 could be a short-wave pass filter that passes blue and green light and reflects red light. In this arrangement, the dominant color (red in this example) is up to three times brighter than in a comparable single-modulator system, because the separate modulation of those colors allows them to be projected over a full frame (rather than only one-third of a frame as would be the case if modulated by a shared modulator). The other two colors (in this example, green and blue) are 50% (i.e., 1.5 times) brighter than in the single chip arrangement because they project over half the frame instead of one third of the frame, and therefore only two colors share the modulator (rather than three colors sharing the modulator). Although it is not necessary to select red as the dominant color, the color chosen for modulation by the unshared (first) DMD is usually the color that requires the greatest amount of boost. The attenuation applied to the dominant color path can be appropriately controlled to boost the red output relative to the green and blue colors to obtain the proper color balance point. If the white light source is uniformly color balanced, a 50% attenuation of the dominant (red) color path can create a uniform color balance with a total projected lumen output 50% higher than a comparable single modulator system.

The second type of architecture modifies the light source 1350 before the filter 1325. For example, the illumination module can be modified to use a transmissive phosphor wheel in an arrangement similar to that described above with reference to FIG. 8.

The wheel may use a single phosphor or two phosphors (with a blue reflecting or transmitting segment) and the spectrum from the yellow and green phosphors is separated into their two components, green and red. For example, a system using a single yellow phosphor may produce a good white point and allow good red selection using a prism, but the green may be poor, given a color point just inside the green point of ITU-R Recommendation BT.709. If a single green phosphor is used, the green point may be good (outside Recommendation 709) but the white point may be poor (very cyanish white point). Two greens and two reds may be produced with the approach using both green and yellow phosphors, but the same sequence may be produced for both colors, so that a single green can be obtained by mixing two greens and a single red can be obtained by mixing two reds.

In the example illumination architecture, the light path has a blue rejection filter for the light (from the phosphor) sent to the green SLM, but during blue times, the blue light can proceed (via the blue bypass path). In the case of an architecture with a blue bypass (such as that shown in FIG. 13), filter 1324 rejects the blue light for the green and yellow phosphors. In the case of a transmissive phosphor system, a filter can be added at the output of the phosphor wheel for the phosphor section and a diffuser can be used for the blue section.

14-21 illustrate additional example architectures with two SLMs for combining individually modulated colors. FIG. 14 shows an example modulation module 1400 that combines illumination from a light source with modulation of a projection beam. In this example, light 1402 is directed to the SLM 1410 by total internal reflection (TIR). The light 1402 enters a prism 1404 and has an angle of incidence at a prism-air interface between the prism 1404 and an air gap 1406. In this example, the prism is glass, although plastic and other suitable materials may be used instead. Because the angle of incidence of the light 1402 on the prism-air interface is greater than the critical angle, the light 1402 reflects onto the SLM 1410 as light 1408. Each pixel of the SLM 1410 is in an on or off state. The on state light reflects at an angle as light 1412. The off-state light reflects at another angle as light 1414. In this example, light 1412 traverses six prism-air interfaces: between prism 1404 and air gap 1406, between air gap 1406 and prism 1416, between prism 1416 and air gap 1418, between air gap 1418 and prism 1420, and between prism 1420 and air. Because light 1412 has an angle of incidence at each of these prism-air interfaces at an angle less than the critical angle of these barriers, light 1412 passes through as shown in FIG. 14. Light 1412 is the desired modulated light used to create an image. Light 1414 has an angle of incidence at the prism-air interface between prism 1416 and air gap 1418 at an angle greater than the critical angle. Thus, light 1414 is reflected as light 1422. In some instances, light 1422 enters a light trap (not shown) to absorb this wasted light. Thus, modulation module 1400 receives light 1402 and provides light 1412 modulated by SLM 1410. This is a three-piece TIR prism that directs the off-state light down a different path than the on-state light.

15 shows another example modulation module 1500. Light 1502 travels through prism 1504 to SLM 1506. On-state light from SLM 1506 reflects as light 1508, which reflects as light 1510. To provide the desired modulated light, light 1510 passes through prism 1512 as shown in FIG. 15. Off-state light 1514 reflects at the prism-air interface (between prism 1504 and air gap 1516) as light 1518. In some examples, light 1516 enters a light trap (not shown) to absorb this wasted light. Because the on-state light reflects by total internal reflection after modulation, the arrangement of FIG. 15 is sometimes referred to as a reverse total internal reflection (RTIR) modulation module.

16 shows another example modulation module 1600. Light 1602 reflects at the prism-air interface (between prism 1604 and air gap 1608) as light 1610. Light 1610 travels to SLM 1616 via prisms 1612 and 1614. On-state light 1618 from SLM 1616 passes through prisms 1614, 1612, 1604, and 1606 to provide the desired modulated light. Off-state light 1620 reflects at the prism-air interface (between prism 1614 and air gap 1622) as light 1624. In some examples, light 1624 enters a light trap (not shown) to absorb this wasted light. Modulation module 1600 is useful in some applications because the angle between prism 1604 and prism 1606 is independently selectable from the angle between prism 1612 and prism 1614. Figure 16 is another prism arrangement that uses a single prism near the DMD to direct the off-state light in a different path than the on-state light.

FIG. 17 illustrates an example combiner 1700. Modulation modules 1702 and 1706 provide modulated light to prism 1710. Prism 1710 includes a dichroic filter 1712 that reflects the color of light 1704 but passes the color of light 1708. For example, light 1708 can be red light and light 1704 can be blue or green light. In this example, dichroic filter 1712 is a long-pass filter that passes the lower frequency red light and reflects the higher frequency green and blue light. As a result, light 1708 and 1704 combine and travel to the projection optics (not shown in FIG. 17) for the desired image.

Figure 18 shows another example combiner 1800. Light 1808 from modulation module 1806 reflects by TIR as light 1816 and is reflected again by TIR at the prism-air interface (between prism 1812 and air gap 1814) as light 1818. Light 1804 from modulation module 1802 passes through prisms 1810 and 1812. As a result, light 1804 and light 1818 are combined and directed to projection optics (not shown in Figure 18) for the desired image.

19A-19C (collectively "FIG. 19") illustrate an example architecture 1900 having a modulation module and combiner as described above in FIGS. 14-18. However, different entrance and exit angles for the modulation module and/or combiner may require changes in the relative positioning of the components. FIG. 19A is a side view of architecture 1900. FIG. 19B is another side view (rotated 90 degrees about the y-axis of FIG. 19A) of architecture 1900 from the perspective of the incoming light 1902. FIG. 19C is a bottom view (rotated 90 degrees about the x-axis of FIG. 19A) of architecture 1900. In this description (e.g., the description of FIGS. 19-21), the terms "top," "bottom," and "side" are merely relative references (with respect to each other) and do not refer to any other frame of reference. For example, even if the "top" in FIG. 19A is directed toward the ground, it is still the "top" in this description. Referring to FIG. 19A, light 1902 travels through lenses 1904 and 1906 to filter 1908. In this example, filter 1908 is a long wavelength pass filter. Light 1902 is provided by a light source such as the light source of FIG. 1A or one of light sources 150 (FIG. 1B), 200 (FIG. 2A), 250 (FIG. 2B), or 1350 (FIG. 13). As shown in FIG. 19C, filter 1908 has a 45 degree angle so that it reflects the higher frequency light 1921 (in this example, blue and green) to mirror 1920. As shown in FIG. 19B, mirror 1920 reflects the higher frequency light 1921 through lens 1924 to modulation module 1932, which includes SLM 1930. As shown in FIG. 19A, red light from light source 1902 travels through filter 1908 as light 1911 to mirror 1910, which reflects such light (as red light 1912) through lens 1914 into modulation module 1916, which includes SLM 1918. Lenses 1914 and 1924 are arranged to distribute the light more evenly across SLM 1918 and SLM 1930, respectively. Combiner 1926 combines the modulated light outputs of modulation modules 1916 and 1932 and passes the combined modulated light to projection optics 1928. However, architecture 1900 is not as compact as other examples described below.

20A-20C (collectively "FIG. 20") show another example architecture having a modulation module and combiner as described above in FIGS. 14-18. As with architecture 1900 (FIG. 19), different input and output angles for the modulation module and/or combiner may require changes in the relative positioning of the components. FIG. 20A is a side view of architecture 2000. FIG. 20B is another side view (rotated 90 degrees about the y-axis of FIG. 20A) of architecture 2000 from the perspective of the incoming light 2002. FIG. 20C is a bottom view (rotated 90 degrees about the x-axis of FIG. 20A) of architecture 2000. Light 2002 is provided by a light source such as the light source of FIG. 1A or one of light sources 150 (FIG. 1B), 200 (FIG. 2A), 250 (FIG. 2B), or 1350 (FIG. 13). As shown in FIG. 20A, light 2002 travels through lenses 2004 and 2006 to filter 2008. In this example, filter 2008 is a long wavelength pass filter. Filter 2008 has a 45 degree angle, so that it reflects the higher frequency light 2010 (in this example, blue and green) through lens 2018 into modulation module 2024, which includes SLM 2022. Red light from light 2002 travels through filter 2008 as light 2013 to mirror 2015 and mirror 2014. Referring also to FIG. 20B, mirror 2014 reflects such light (as red light 2016) through lens 2020 into modulation module 2030, which includes SLM 2032. Lenses 2018 and 2020 are arranged to provide a more uniform distribution across SLM 2022 and SLM 2032, respectively. The combiner 2026 combines the modulated light outputs of the modulation modules 2024 and 2030 and passes the combined modulated light to the projection optics 2028.

Figure 21 shows another example architecture having a modulation module and combiner as described above in Figures 14-18. As with architectures 1900 (Figure 19) and 2000 (Figure 20), different entrance and exit angles for the modulation module and/or combiner may require changes in the relative positioning of components. In architecture 2100, light 2102 travels through lenses 2104 and 2106 to filter 2108. Light 2102 is provided by a light source such as the light source of Figure 1A or one of light sources 150 (Figure 1B), 200 (Figure 2A), 250 (Figure 2B), or 1350 (Figure 13). In this example, filter 2108 is a long wavelength pass filter. Filter 2108 reflects higher frequency light 2110 (in this example, blue and green) into modulation module 2114, which includes SLM 2116. The lower frequency light 2112 (red in this example) passes through the filter 2108 into the modulation module 2118, which includes the SLM 2120. A combiner 2126 combines the modulated light 2124 and the modulated light 2122, and passes the combined modulated light through the projection optics 2128 to the target image plane. The higher frequency light 2110 and the lower frequency light 2112 may also pass through additional lenses (not shown for clarity) to place the filter 2108 in the telentric light space, so that the incoming light (when separated) may have less color variation across the SLMs 2116 and 2120. The architecture 2100 is very compact.

Figure 22 is a flow chart of an example method 2200. Method 2200 begins with step 2202 of directing a first color of light onto a phosphor that produces a second color of light. In at least one example, the first color is blue and the second color is yellow. The first color of light can be selectively applied to the phosphor using, for example, one of the arrangements of Figures 1A-1B and 2A-2B. In step 2204, the yellow light emitted by the phosphor (second color of light) is filtered to produce a third and fourth color, such as green and red. In step 2206, the light of one of the colors (e.g., green) is modulated by a first spatial light modulator, such as the DMD of Figure 1A. In step 2208, the other two colors (e.g., red and blue) are alternately modulated by a second spatial light modulator, as described above with respect to Figure 1A. Step 2210 combines the outputs of the two modulators.

Figure 23 is a flow chart of another example method 2300. Method 2300 begins with step 2302 of directing a first color onto a phosphor that produces light of a second color. In at least one example, the first color is blue and the second color is yellow. The first color light is selectively applied to the phosphors, for example, using a phosphor wheel. For example, step 2304 directs the first color light onto a second phosphor to produce a third color (e.g., green). In step 2306, the light from the phosphor is filtered into component colors, such as red and green. In step 2308, the light of one of the colors (e.g., green) is modulated by a first spatial light modulator, such as a DMD. In step 2310, the other two colors (e.g., red and blue) are alternately modulated by a second spatial light modulator, as described above. Step 2312 combines the outputs of the two modulators for projection.

U.S. Patent Application No. 15/913,690, filed March 6, 2018, is incorporated herein by reference. Also, U.S. Patent Nos. 9,939,719 and 9,664,989 are incorporated herein by reference.
U.S. Patent Application No. US15/913,690 U.S. Pat. No. 9,939,719 U.S. Pat. No. 9,664,989

Modifications in the described examples are possible and other examples are possible within the scope of the claims.

Claims (12)

1. A projector, comprising:
a first light source for generating a first light having a first color;
a second light source for generating a second light having the first color;
a third light source for generating a third light having the first color;
a filter for reflecting the first light and the second light and for passing light having a second color and a third color ;
a fixed phosphor having a first side optically coupled to the third light source and a second side optically coupled to the filter,
generating a fourth light having the second color and the third color in response to receiving the third light at the first side;
generating a fifth light having the second color and the third color in response to receiving the second light at the second side.
and
a dichroic mirror for passing the first light , a first portion of the fourth light having the second color , and a first portion of the fifth light having the second color, and for reflecting a second portion of the fourth light having the third color and a second portion of the fifth light having the third color ;
Including,
The second light source and the third light source are brightened and the first light source is not brightened;
The first light source is brightened and the second light source and the third light source are not brightened.
The projector is configured to alternate between: 2. The projector according to claim 1,
a first spatial light modulator for receiving and modulating a first portion of the fourth light from the dichroic mirror;
a second spatial light modulator for receiving and modulating a second portion of the fourth light from the dichroic mirror;
a combiner for combining a first portion of the fourth light modulated by the first spatial light modulator and a second portion of the fourth light modulated by the second spatial light modulator;
The projector further comprises: 2. The projector according to claim 1,
A projector, wherein the first and second light sources are laser light sources. 3. The projector according to claim 2,
A projector, wherein the first spatial light modulator is a first modulation module and the second spatial light modulator is a second modulation module. 3. The projector according to claim 2,
A projector, wherein the first and second spatial light modulators are digital micromirror devices. 3. The projector according to claim 2,
A projector, wherein the combiner is a prism including a dichroic layer. 2. The projector according to claim 1,
The first color is blue, the second color is red, and the third color is green. 2. The projector according to claim 1,
A projector, wherein the first light source is a laser diode. 3. The projector according to claim 2,
a first total internal reflection (TIR) prism for providing a first portion of the fourth light from the dichroic mirror to the first spatial light modulator;
a second TIR prism for providing a second portion of the fourth light from the dichroic mirror to the second spatial light modulator;
The projector further comprises: 10. The projector according to claim 9,
the first TIR prism includes a first prism, a second prism, and a first air interface between the first prism and the second prism;
The projector, wherein the second TIR prism includes a third prism, a fourth prism, and a second air interface between the third prism and the fourth prism. 2. The projector according to claim 1,
The second light source is configured to pump a second side of the solid phosphor, and the third light source is configured to pump a first side of the solid phosphor. 2. The projector according to claim 1,
The projector, wherein the third light source is a blue laser diode.

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