Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
  • G02B27/0938—Using specific optical elements
  • G02B27/095—Refractive optical elements
  • G02B27/0972—Prisms
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
  • G02B27/0905—Dividing and/or superposing multiple light beams
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/1006—Beam splitting or combining systems for splitting or combining different wavelengths
  • G02B27/102—Beam splitting or combining systems for splitting or combining different wavelengths for generating a colour image from monochromatic image signal sources
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/14—Beam splitting or combining systems operating by reflection only
  • G02B27/145—Beam splitting or combining systems operating by reflection only having sequential partially reflecting surfaces
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/14—Beam splitting or combining systems operating by reflection only
  • G02B27/149—Beam splitting or combining systems operating by reflection only using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N9/00—Details of colour television systems
  • H04N9/12—Picture reproducers
  • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
  • H04N9/3102—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators
  • H04N9/3105—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N9/00—Details of colour television systems
  • H04N9/12—Picture reproducers
  • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
  • H04N9/3141—Constructional details thereof
  • H04N9/315—Modulator illumination systems

Definitions

• the present invention relates an improved system and methodology for providing multi-colored illumination without increasing the etendue of the system.
• a liquid crystal display (hereafter "LCD”) is a known device used to control the transmission of polarized light energy.
• the LCD may be either clear or opaque depending on the current applied to the LCD.
• projection system commonly use an array containing numerous LCDs to form an image source.
• the projection system inputs high intensity polarized light energy to the LCD array (also called an imager), which selectively transmits some of the inputted light energy to form a projection of a desired image. Because a single LCD is relatively small, numerous LCDs can be packed together into the array, thereby forming an imager that can produce a high resolution image.
• a projection system must first polarize the light input to the LCD.
• light energy from a light source such as a bulb
• the LCD projector since this light input to the LCD imager must be in one orientation (i.e., either p-polarization or s-polarization), the LCD projector generally uses only half of the light energy from the light source.
• various mythologies have been developed to capture the light energy of unusable polarization, to convert the polarization of this captured light energy, and then to redirect the converted light energy toward the LD imager.
• the present invention uses a waveguide system to perform the polarization recovery function in an LCD projection system.
• the present invention's waveguide polarization recovery system both polarizes the input light energy for use with an LCD imager and converts the polarity of unusable light energy to add to the illumination of the LCD imager.
• the compact polarization recovery waveguide system generally includes the following optical components that are integrated into a single unit: (1) an input waveguide that inputs non-polarized light energy into the system; (2) an output waveguide that removes polarized light energy from the system; (3) a polarized beam splitter that receives the light energy from the input waveguide and transmits light energy of a first polarization type and reflects light energy of a second polarization type, and (4) a wave plate that modifies the polarization of either the transmitted or reflected light energy.
• the polarization recovery system also generally includes one or more mirrors that are positioned as needed to direct the transmitted and/or reflected light energy to the output waveguide.
• the input and output waveguides may be shaped as needed by the projection system. For example, either one or both of the input and output waveguides may be tapered up or down as needed to produce a desired image.
• the input and output waveguides are configured to have either a substantially parallel or a substantially perpendicular orientation.
• the output waveguide directly receives light energy transmitted by the beam splitter. In this way, light energy enters and exits the polarization recovery system in substantially the same direction.
• the input and the output waveguides may be positioned substantially perpendicular to each other such that the light energy exits the polarization recovery system at a right angle from the direction it enters, hi configurations having input and output waveguides of perpendicular orientation, a mirror receives the light energy transmitted by the polarized beam splitter and redirects this energy by 90°C toward the output waveguide.
• the polarization recovery waveguide system of the present invention combines the above-enumerated list of optical components into a single, compact unit.
• the waveguide polarization recovery system further includes one or more "gaps" of optically clear material positioned between the optical components to encourage the occurrence of total internal reflection that minimizes the loss of the optical energy by the system.
• each LED In the field of LED illumination, each LED generally emits a single color.
• N LEDs are used, typically N > 2.
• N LEDs e.g., 2 LEDs
• N LEDs are place side by side and coupled into the same target.
• the desired color and brightness can be achieved.
• the etendue of a typical illumination system must be increased as the area of emission is increased. Accordingly, in accordance with an embodiment of the present invention, a light pipe based system combines the colors without increasing the etendue.
• a multi-colored illumination system comprising a beam combiner.
• the beam combiner comprises two triangular prisms and a filter for transmitting a first light and reflecting a second light, each light having a different wavelength.
• the beam combiner combines the transmitted first light and the reflected light to provide a combined beam.
• Each surface of the triangular prisms is polished, thereby combining the lights without increasing etendue of the multicolored illumination system.
• a multi-colored illumination system comprises n beam combiners for combining n+1 lights, where N > 2, each light having a different wavelength, and a low index glue or air gap provided between each beam combiner.
• Each beam combiner comprises two triangular prisms, each surface of the triangular prisms being polished and a filter for transmitting a combined beam received from a previous beam combiner and reflecting a new light from n+1 lights which has not been previously transmitted or reflected. The beam combiner combines the transmitted combined beam and the reflected new light to provide a new combined beam.
• the new combined beam is provided to the next beam combiner if the beam combiner is not the last beam combiner or outputs the new combined beam if the beam combiner is the last beam combiner.
• the low index glue or air gap between each beam combiner enables the multi-colored illumination system to combined all of the lights without increasing etendue of the multi-colored illumination system.
• a multi-colored illumination system comprises at least two LEDs, a light pipe associated with each LED, an X-cube and a low index glue or air gap.
• the two LEDs provide two lights having two different wavelengths.
• the X-cube combines the lights received from each light pipe associated with a LED to provide an output beam.
• the low index glue or air gap is provided between each of the light pipe and the X-cube, thereby combining the lights without increasing etendue of the multi-colored illumination system.
• a light engine comprising the multi-colored illumination system as aforesaid.
• a projection display system comprising the light engine as aforesaid, at least one light modulator panel for modulating light in accordance with a display signal; and a projection lens for projecting the modulated light onto a display screen.
• a method for multi-colored illumination comprises the steps of combining by a first beam combiner a first light transmitted by a first filter and a second light reflected by the first filter to provide a combined beam; combining by a second beam combiner the combined beam transmitted by a second filter and a third light reflected by the second filter to provide an output beam, each light having different wavelength; and providing a low index glue or air gap between the beam combiners, thereby combining the lights without increasing etendue.
• a method for multi-colored illumination comprises the steps of combining by an X-cube at least two lights having two different wavelengths received from corresponding two light pipes; and providing a low index glue or air gap between each light pipe and the X-cube, thereby combining the lights without increasing etendue.
• FIGs. 1-4 and 6-10 are schematic diagrams of the waveguide polarization recovery system in accordance with various embodiments of the present invention.
• FIG. 5 is a schematic diagram of a compact projection device incorporating the polarization recovery system in accordance with an embodiment of the present invention
• Fig. 11 is a schematic diagram of a light pipe comprising a 90° turn without an air gap or low index glue
• Fig. 12 is a schematic diagram of a light pipe comprising a 90° turn with air gaps or low index glue in accordance with an embodiment of the present invention
• FIG. 13A-B are schematic diagrams of a light pipe based color system in accordance with an embodiment of the present invention.
• Fig. 14 is a schematic diagram of a light pipe based color system in accordance with an embodiment of the present invention.
• Fig. 15 is a schematic diagram of a light pipe based color system comprising a X-cube in accordance with an embodiment of the present invention
• Fig. 16 is a schematic diagram of a light pipe based color system comprising a X-cube in accordance with an embodiment of the present invention
• Fig. 17 is a schematic diagram of a light pipe based color system comprising an array of LED sources in accordance with an embodiment of the present invention
• Fig. 18 is a schematic diagram of a projection system incorporating the light pipe system of the present invention.
• Fig. 19 is a graph illustrating the peak or high intensity sections of blue, green and red light.
• Fig. 20 is a graph illustrating the red light formed from combining three different red lights having different high intensity sections.
• a compact waveguide polarization recovery system 10 comprises an input waveguide 20, a polarizing beam splitter ("PBS") 30, a wave plate 40, which can be a half-wave plate, or a quarter-wave plate depending on the configuration, and an output waveguide 50.
• the waveguide polarization recovery system 10 generally further includes mirrors 60 as needed to direct the light stream between the input and output waveguides, 20 and 50. The following discussion first summarizes several possible configurations for the waveguide polarization recovery system 10 and then describes the individual elements in greater detail.
• Figs. 1, 3, and 6 illustrate one configuration of the waveguide polarization recovery system 10 in which the output light energy is substantially parallel with the input light energy.
• the input waveguide 20 introduces unpolarized input light from a light source or LED light source at incidence to the PBS 30.
• the illustrated PBS 30 transmits p-polarized light, and so the p-polarized portion of the input light energy continues through in the same direction as the initial input while the s-polarized light is reflected in a perpendicular direction to the initial direction of input.
• the half-wave plate 40 is positioned to receive the reflected s-polarized light and convert it to p-polarized.
• mirror 60 redirects the converted energy from the half-wave plate 40 back to the initial direction of input.
• Both the transmitted light energy from the PBS 30 and the converted light energy from the half-wave plate 40 are recombined in the output waveguide and mixed.
• the output light energy has a uniform intensity profile and is polarized. It should be appreciated that an output of the opposite polarization may be produced through the use of a PBS 30 that only transmits s-polarized light.
• Figs. 2, 4, and 7-8 illustrate an embodiment of the waveguide polarization recovery system 10 that has an alternative configuration in which the output light energy is perpendicular to the original input light energy.
• the input waveguide 20 introduces unpolarized input light at incidence to the PBS 30.
• the PBS 30 performs the same function of transmitting the p-polarized light, and so the p- polarized portion of the input light energy continues through in the same direction as the initial input while the s-polarized light is reflected in a perpendicular direction to the initial direction of input.
• one mirror 60 redirects the transmitted p-polarized portion of the input light energy by 90° toward the output waveguide 50.
• the reflected s-polarized light from the PBS 30 propagates once through a quarter-wave plate 40', and a second mirror 60 then returns the reflected light energy to the quarter-wave plate 40' for another pass.
• the second pass is also in the direction of the output waveguide 50. Because the reflected s-polarized light passes twice through the quarter-wave plate 40', s-polarized light is shifted by a half-wave to become p- polarized twice with the mirror as shown. Again, both p-polarized outputs will be mixed in the output waveguide, producing a uniform intensity output.
• the system requires only two optical sections: A first section formed through the combination of the input waveguide 20, the PBS 30, the quarter-wave plate 40' and a mirror 60; and a second section formed through the combination of the output waveguide 50 and a second mirror 60. Therefore, the system has a simple design and a relatively low cost. Positioning the output light energy perpendicular to the original input light energy also has the advantage of allowing a more compact projection system, as described in greater detail below.
• Figs. 9 and 10 illustrate configurations in which the half- wave plate 40 is positioned to receive light energy transmitted by the PBS 30.
• the half- wave plate 40 is optically positioned between a mirror 60 and the output waveguide 50.
• the half-wave plate 40 receives transmitted light energy that has first been redirected by a mirror 60.
• the half- wave plate 40 is placed between the PBS 30 and mirror 60.
• the transmitted light energy from the PBS 30 is first repolarized before being redirected toward the output waveguide 50.
• the configurations of Figs. 9-10 are advantageous because the input light energy only passes through the polarization layer of the PBS 30 once, thus reducing the loss of optical energy in the system 10.
• the above-described configuration of the Figs. 2, 4, and 7-8 requires some of the input light energy to pass through the PBS 30 twice.
• the input waveguide 20 is typically an integrator that collects the light from a light source, such as an arc lamp, and mixes the light through multiple reflections to produce a more uniform intensity profile into the waveguide polarization recovery system 10.
• the output waveguide 50 is typically an integrator that collects the light from the waveguide polarization recovery system 10 and mixes the light through multiple reflections to produce a more uniform intensity profile for illumination of the imager.
• the input waveguide 20 and the output waveguide 50 may be, for example, single core optic fibers fused bundles of optic fibers, fiber bundles, solid or hollow square or rectangular light pipes, or homogenizers, which can be tapered or un-tapered.
• the input waveguide 20 and the output waveguide 50 are typically rectangular in cross-section to correspond with the shape of the imager and the final projected image.
• the input waveguide 20 and the output waveguide 50 wave can be made from glass, quartz, or plastic depending on the power-handling requirement.
• Either one or both of the input waveguide 20 and the output waveguide 50 can have an increasing or decreasing taper as needed for the projection system.
• Fig. 3-4 and 6-10 illustrate embodiments of the waveguide polarization recovery system 10 in which the input waveguide 20' is a tapered rod with the input cross-section matched to the area of the light source and the output cross-section related to the dimension of a LCD imager. The final dimensions for the input waveguide 20 may vary as needed to minimize stray light loss in the optical projection system.
• Fig. 8 illustrates an embodiment of the waveguide polarization recovery system 10 in which the output waveguide 50' is also tapered.
• Tapering of the output waveguide 50' is advantageous because, depending on the performance parameters of the PBS 30, the wave plate 40, and the output requirements for the projection system, polarization recovery may not always be done at the same numerical aperture as the output aperture.
• the performances of the PBS 30 and the wave plate 40 are better at smaller numerical apertures, and as a result, advantageous increases in performance are achieved by transforming the input light energy into a larger area with a small numerical aperture and then transforming the light energy back into larger numerical aperture at the output of the output waveguide 50'.
• the tapering of the input wave guide 20 and the output waveguide 50 can be selected to match the overall performance requirements of the projection system, and similarly, the input and output waveguides can be tapered in either direction.
• the waveguide polarization recovery system 10 further includes PBS 30.
• the PBS 30 is a well-known optical element that transmits light energy of one polarization while reflecting light energy of a different polarization.
• the PBS 30 is a rectangular prism of optically clear material, such as plastic or glass, that has a polarizing coating applied to the diagonal surface.
• the PBS 30 may be composed of a material that selectively transmit light energy depending on the polarization of the light energy.
• any of these alternative PBS 's may be employed in the waveguide polarization recovery system 10 of the present invention. Because the PBS 30 is a well known and commercially available item, it is not discussed further.
• the wave plate 40 is an optically transparent component that modifies the polarization of light energy that passes through the wave plate 40.
• the wave plate 40 typically changes the propagating of light in one axis, thus changes the polarization.
• the wave plate 40 may be either a half-wave or quarter-wave as needed by the specific configuration of the waveguide polarization recovery system 10. Overall, the wave plate 40 is a well known and commonly available item and will not be discussed further.
• the waveguide polarization recovery system 10 may further include one or more mirror 60 as needed to direct the light energy through the waveguide polarization recovery system 10. While mirrors are commonly known to be metal-coated glass surfaces or polished metal, the mirrors 60 should not be limited to this common definition for the purpose of this invention. Instead, mirrors 60 should be considered any optical component capable of reflecting or redirecting light energy. For example, mirrors 60 may be replaced with a light pipe, e.g., a prism or light pipes having a turn, e.g., 90° turn, (collectively referred to herein as a prism), that use the angle of incidence to capture and redirect light energy. For example, Figs.
• FIGS. 9 and 10 illustrate a waveguide polarization recovery system 10 that has a prism to guide or redirect light energy transmitted by the PBS 30 toward the output waveguide 50.
• a prism to guide or redirect light energy transmitted by the PBS 30 toward the output waveguide 50.
• total internal reflection at the prism can be used, and as a result, the coating is not necessary.
• the waveguide polarization recovery system 10 further includes one or more optically clear area, low index glue, or "gaps" 70, between the other optical elements (collectively referred to herein as the gap).
• the gaps 70 may be pockets of air left between the optical components.
• the gap 70 can also be filled with low index epoxy or other transparent material such that the total internal reflection still occurs, but the assembly of the components will be simplified.
• Fig. 6 illustrates a configuration having gap 70 between the input waveguide 20 and the PBS 30.
• This gap 70 ensures that light energy reflected by the diagonal PBS 30 is turned by 90° toward the quarter-wave plate 40' because total internal reflection from the interface between the PBS 30 and the gap 70 prevents the light energy from returning instead to the input waveguide 20 and exiting as a loss.
• the waveguide polarization recovery system 10 in Fig. 6 also has other gaps 70 to promote total internal reflection between the different optical elements.
• Fig. 7 illustrates a waveguide polarization recovery system 10 in which gaps 70 have been added to a polarization recovery system with a tapered input waveguide 20 and perpendicularly configured output waveguide 50 illustrated in Fig. 4. Again these gaps 70 increase the efficiency by encouraging total internal reflection between the optical components. As illustrated in Figs. 6-7, the gaps 70, while increasing the efficiency of the system, cause the waveguide polarization recovery system 10 to become more complex with an increased number of discrete parts.
• the gaps 70 further serve the purpose of improving the performance of the prism 60' that serves as a mirror to direct the light energy toward the output waveguide 50.
• the gap 70 is needed between the PBS 30 and the prism 60' such that the light reflected from the hypotenuse of the prism 60', back toward the PBS 30, hits this interface of the gap 70 and is internally reflected toward the output waveguide 50. In this way, efficiency of the system is improved by minimizing loss.
• gaps 70 may be further increased through the use of anti-reflection coating on both surfaces such that the transmitted light suffers minimal loss.
• Fig. 5 illustrates a projector 100 that employs the waveguide polarization recovery system 10.
• the projector 100 consists of a light collecting system 110, which is this illustrated example has two paraboloid reflectors and a retro-reflector that increase the output by reflecting the light from a light source 120 back into itself.
• the arc of the light source 120 is placed at a focus of the first paraboloid reflector and the proximal end of the input waveguide 20 is at the focus of the second paraboloid reflector.
• this light collection system 110 is provided merely for illustration, and many other light collection systems are known and may be used.
• the light source 120 may be an arc lamp, such as xenon, metal-halide lamp, HID, or mercury lamps, or a filament lamp, such as a halogen lamp, provided that the system is modified to accommodate the non-opaque filaments of the lamp.
• arc lamp such as xenon, metal-halide lamp, HID, or mercury lamps
• filament lamp such as a halogen lamp
• the input waveguide 20 is a tapered light pipe that is designed to match the light input collected from the light collecting system 110 to the optical needs of an LCD imager 150.
• the light output of the input waveguide 20 is polarized by the PBS 30 and the other polarization is recovered by the quarter- wave plate 40'.
• the output waveguide 50 then directs the polarized optical energy toward the LCD imager 150.
• the light output in the output waveguide 50 is then incident into a second PBS 130 whose orientation is matched to the polarization of the incident light to minimize the loss.
• a color wheel 140, or other type of color section system, and the reflective LCD imager 150 create the projected image by the projection lenses 160 in a traditional manner. As shown in Fig. 5, the number of optical elements is minimal and, as the result, the cost for the projector is relatively low.
• the waveguide polarization recovery system 10 may be used in other types of projection systems.
• the projector may also use two or three imagers 150 to define the projected image.
• the imager 150 may also be a reflective display using liquid crystal on silicon (“LCOS”) technology, or any other type of systems that requires polarized systems.
• LCOS liquid crystal on silicon
• the light pipe system 200 comprises light pipes 20, 50 comprising air gaps or low index glue 70 as shown in Fig. 12.
• the light, e.g., light paths (a) and (c), that are lost in Fig. 11 are recaptured by total internal reflection and collected by the output light pipe 50 of the light pipe system 200.
• the color system 300 comprises beam combiners 310, 320, air gaps or low index glue 70 and three light sources, namely, red (R), green (G), and blue (B).
• Each light input is coupled directly or indirectly through a light pipe or lens system 200 (not shown but such as one shown in Fig. 12), into the color system 300.
• Each beam combiner comprises a filter and two prisms or beam splitters, preferably triangular prisms with all of the surfaces polished.
• the first beam combiner 310 with filter A transmits red light (R) and reflects green light (G). It is appreciated that the filter A is controlled, tuned or selected to transmit red light (R) and reflect green light (G).
• the red light (R) from the input is transmitted by the first combiner 310 and the green light (G) from the other face of the first combiner 310 is reflected.
• the reflected green light (G) combines with the transmitted red light (R) and exit together out of the same face of the combiner 310.
• the combined red/green light (R, G) then enters the second combiner 320 with a filter B, which transmits the red and green light (R, G), and reflects the blue light (B). It is appreciated that the filter B is controlled, tuned or selected to transmit red and green light (R, G) and reflect the blue light (B).
• the red/green light will continue to pass through the second combiner 320 and the blue light (B) from the blue input is reflected by the second combiner 320.
• the reflected blue light (B) combines with the transmitted red and green light (R, G) and the combined light (R, G, B) exit the color system 300 together. It is appreciated that the output intensity and color are controlled by the amount of each color light inputted into the color system 300. Additionally, it is appreciated that the placement of light source is arbitrary and depends on the application of the color system 300.
• the blue light (B) can be inputted to the first beam combiner 310 provided that the filter A is now tuned to reflect blue light (B) instead of green light (G).
• the output beam of the color system 300 of the present invention occupies the same cross-section area of an individual input beam, thus preserving the same etendue of a single light source.
• the efficient coupling of the light is accomplished by providing an air gap or low index glue 70 between the various optical components, such the beam combiners 310, 320.
• the combined output beam of the color system 300 of the present invention can be used for fiber optic illuminations or for projection display applications, e.g., a light engine for a projection display system.
• the color system 300 comprises a beam combiner 310 and two light sources, namely, red (R) and green (G). Each light input is coupled directly or indirectly through a light pipe or lens system 200 (not shown but such as one shown in Fig. 12), into the color system 300.
• Each beam combiner comprises a filter and two prisms or beam splitters, preferably triangular prisms with all of the surfaces polished.
• the beam combiner 310 with filter A transmits red light (R) and reflects green light (G). It is appreciated that the filter A is controlled, tuned or selected to transmit red light (R) and reflect green light (G).
• the red light (R) from the input is transmitted by the first combiner 310 and the green light (G) from the other face of the first combiner 310 is reflected.
• the reflected green light (G) combines with the transmitted red light (R) and exit together out of the same face of the combiner 310.
• the output intensity and color are controlled by the amount of each color light inputted into the color system 300.
• the placement of light source is arbitrary and depends on the application of the color system 300. That is, instead of green light (G) being inputted to the beam combiner 310, the blue light (B) can be inputted to the beam combiner 310 provided that the filter A is now tuned to reflect blue light (B) instead of green light (G).
• the output beam of the color system 300 of the present invention occupies the same cross-section area of an individual input beam, thus preserving the same etendue of a single light source.
• the efficient coupling of the light is accomplished by the reflective polished surfaces of the triangular prisms.
• the combined output beam of the color system 300 of the present invention can be used for fiber optic illuminations or for projection display applications, e.g., a light engine for a projection display system.
• each input light source (R, G or B) in Fig. 13A-B is a LED light source coupled to a straight or tapered light pipe 330, as shown in Fig. 14.
• a tapered up light pipe 330 is shown in Fig. 14, it is appreciated that a tapered down light pipe 330 can be also utilized.
• the light sources can be a plurality of LED lights sources or arrays of LED light sources I 1 - I n , each providing light with different color or wavelength where n ⁇ 2.
• a light source Io can be provided as an input to the beam combiner BC 1 which transmits the light from the light source Io to the next beam combiner BC 2 .
• each light source I j Light or light energy from each light source I j is reflected by the corresponding beam combiner BC j comprising a filter F j matching the wavelength of the light from the corresponding light source I j .
• the reflected light I j combines with the transmitted light I 0 ... I j-1 and the combined light Io ... I j then enters the next beam combiner BCJM- Finally the combined light I 0 ... I 11 exits the beam combiner BC n and enters the straight, tapered up or tapered down output light pipe 430
• each light source can be coupled to a straight, tapered up or tapered down light pipe 330 as shown in Fig. 14.
• a plurality of LEDs which generate various colors can be used so that a large area is covered in the color coordinate space.
• a n-colored projection display system comprises a n different LED light sources (I 1 ... I n ) providing n different colored light or lights with n different wavelengths, as shown in Fig. 17.
• the filter Fj is controlled, tuned or selected to match the wavelength ⁇ j of the LED light source I j such that it reflects only light having wavelength ⁇ j .
• the brightness of the output light can be controlled and increased with appropriate selection of the filters and light sources to provide a more vivid and intense colors.
• each filter F j can be controlled, tuned or selected to filter out the low-intensity portion of the light or light energy from the corresponding light or LED source, thereby propagating only high-intensity portion of the light and resulting in a brighter output beam.
• multiple LED light sources can be used to enhance a single color, e.g., red.
• each light has a high-intensity section, e.g., the red light has a high-intensity section X R and the blue light has a high-intensity section ⁇ .
• the red light has a high-intensity section X R
• the blue light has a high-intensity section ⁇ .
• three different red lights R 1 , R 2 and R 3 respectively having high-intensity sections XR 1 , XR 2 and XR 3 are combined to form a single high-intensity red light to be inputted into the X-cube 410 or the beam combiner 310, 320 or BCj.
• the corresponding filters F R1 , F R2 and F R3 respectively filter out the low-intensity sections of the red lights R 1 , R 2 and R 3 .
• the color system 400 comprises a X-cube color combiner 410 (or X-cube 410) for combining beams of light without increasing the etendue of the color system 400.
• Each light source (Fig. 16) or a LED light source (Fig. 15) is coupled to a straight, tapered up or tapered down light pipe 420.
• the red light (R) from the red light source or red LED light source enters the X-cube 410 from a first input face of the X-cube 410 via the straight, tapered up or tapered down light pipe 420.
• the red light (R) is transmitted by the X-cube 410 and exits out of the output face of the X-cube 410 and into a straight, tapered up or tapered down output light pipe 430.
• the green light (G) from the green light source or the green LED light source enters the X-cube 410 from a second input face of the X- cube 410 via the straight, tapered up or down light pipe 420.
• the X-cube 410 reflects the green light (G).
• the reflected green light (G) combines with the transmitted red light (R) and exit together out of the same output face of the X-cube 410 and into the straight, tapered up or tapered down output light pipe 430.
• the blue light (B) from the blue light source or the blue LED light source enters from a third input face of the X-cube 410 via the straight, tapered up or tapered down light pipe 420.
• the X-cube reflects the blue light (B).
• the reflected blue light (B) combines with the transmitted red light (R) and the reflected green light (G), and exit together out of the same output face of the X-cube 410 and into the straight, tapered up or tapered down output light pipe 430.
• the light pipes 420, 430 can be, for example, single core optic fibers fused bundles of optic fibers, fiber bundles, solid or hollow square or rectangular light pipes, or homogenizers, which can be tapered up, tapered down or un-tapered.
• the output intensity and color are controlled by the amount of each color light inputted by the corresponding light source or LED light source into the color system 400. Additionally, it is appreciated that the placement of light source is arbitrary and depends on the application of the color system 400. That is, instead of green light (G) being inputted to the second input face of the X- cube 410, the red light (R) can be inputted to the second input face of the X-cube 410.
• the output beam of the color system 400 of the present invention occupies the same cross- section area of an individual input beam, thus preserving the same etendue of a single light source.
• the efficient coupling of the light is accomplished by providing an air gap or low index glue 70 between the various optical components, such as X-cube and the straight, tapered up or tapered down light pipes 420, 430.
• the combined output beam of the color system 400 of the present invention can be used for fiber optic illuminations or for projection display applications, e.g., a light engine for a projection display system.
• the efficient coupling of the light is accomplished by providing an air gap or low index glue 70 between the various optical components, such as light pipes 20, 50, 330, prisms and beam combiners 310, 320, BC 1 - BC n .
• These air gaps or low index glue 70 provide total internal reflections for angled light to be reflected back in ⁇ O the color system 300 which would otherwise be lost, thereby minimizing or eliminating loss of light or light energy.
• a method for multi-colored illumination comprises the steps of combining by a first beam combiner 310 a first light (R) transmitted by a first filter A and a second light (G) reflected by the first filter A to provide a combined beam; combining by a second beam combiner 320 the combined beam transmitted by a second filter B and a third light (B) reflected by the second filter B to provide an output beam, each light having different wavelength; and providing a low index glue or air gap 70 between the beam combiners 310, 320, thereby combining the lights without increasing etendue.
• a method for multi-colored illumination comprises the steps of combining by an X-cube 410 at least two lights having two different wavelengths received from corresponding two light pipes 330; and providing a low index glue or air gap 70 between each light pipe 330 and the X-cube 410, thereby combining the lights without increasing etendue.
• Fig. 17 in accordance with am embodiment of the present invention, there is illustrated a schematic diagram of the light projection system incorporating the light pipe based color system of the present invention.
• the output from the LED light source 510 e.g., any of the color systems described herein, is inputted into the projection engine 520 (e.g., digital light processing (DLP), liquid crystal on silicon (LCOS), high temperature poly-silicon (HTPs), and the like) which creates the projected image by the projection lens 530 in a traditional manner.
• the projection engine 520 comprises at least one modulator panel for modulating light in accordance with a display signal and the projection lens 530 projects the modulated light onto a display screen.
• the system can also be implemented using round prisms and filters.
• solid tapered light pipes 330, 420, 430 are shown in Figs. 14, 15 and 17, other coupling configurations including compound parabolic concentrators (CPCs), lenses, solid or hollow CPC or light pipes, and any other imaging or non-imaging systems can be used.
• the tapered light pipe has a lensed output surface.
• the input of the light pipe is also shaped to increase the coupling efficiency from the LED light source.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Projection Apparatus (AREA)
• Non-Portable Lighting Devices Or Systems Thereof (AREA)
• Optical Elements Other Than Lenses (AREA)

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• 2006
  • 2006-02-09 KR KR1020077018222A patent/KR20070115882A/ko not_active Application Discontinuation
  • 2006-02-09 CA CA002594462A patent/CA2594462A1/en not_active Abandoned
  • 2006-02-09 WO PCT/US2006/004405 patent/WO2006086458A2/en active Application Filing
  • 2006-02-09 EP EP06734567A patent/EP1846799A4/de not_active Withdrawn

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