KR20140056355A - Optical projection subsystem - Google Patents

Abstract

The projection subsystem includes a light engine that provides a condenser lens, a collimator, and at least one solid state light emitter. The projection lens assembly receives the image and provides a projection beam having a luminous flux level. The projection subsystem has portability effectiveness.

Description

[0001] OPTICAL PROJECTION SUBSYSTEM [0002]

Cross-reference to related application

This application is related to U.S. Provisional Application No. 60 / 820,894, filed July 31, 2006, the contents of which are incorporated herein by reference in its entirety; U.S. Provisional Patent Application No. 60 / 820,887, filed July 31, 2006, the content of which is incorporated herein by reference in its entirety; U.S. Provisional Patent Application No. 60 / 820,888, filed July 31, 2006, the content of which is incorporated herein by reference in its entirety; U.S. Provisional Patent Application No. 60 / 820,883, filed July 31, 2006, the contents of which are incorporated herein by reference in its entirety; U.S. Provisional Patent Application No. 60 / 821,032, filed August 1, 2006, the contents of which are incorporated herein by reference in its entirety; U.S. Provisional Patent Application No. 60 / 838,988 filed on August 21, 2006, the contents of which are incorporated herein by reference in its entirety; And U.S. Provisional Patent Application No. 11 / 772,609, filed July 2, 2007, the contents of which are incorporated herein by reference in its entirety.

An optical projector is used to project an image onto a surface so that it can be viewed by a group of people. An optical projector includes an optical projector subsystem including a lens, a filter, a polarizer, a light source, an image forming device, and the like. Fixed front and rear electronic projectors are known to be used for training, home theater, and business conferencing. Known light sources include blackbody lamps, gas discharge lamps, and solid state sources such as lasers, light emitting diodes (LEDs) and organic light emitting diodes (OLEDs). Head-mounted displays (HMDs) are known for their personal use. In mobile applications, there is a need to miniaturize optical projectors in terms of volume and thickness, and to make them extremely power efficient while maintaining low power consumption, low cost and high image quality.

However, the large dimensions and high power consumption of conventional optical projection subsystems limits the effort to produce truly portable projectors. There is a need for a method and an optical projection subsystem that both provide miniaturization and efficiency to project a good quality image in a cost effective manner.

A projection subsystem is disclosed. The projection subsystem includes an illumination subsystem that provides an incoherent, homogenized light beam. The illumination subsystem includes a condenser lens, a collimator, and at least one solid state light emitter. The solid state light emitters receive the power level and can be coupled to a heat sink.

The projection subsystem includes an image forming device. The image forming apparatus receives the image data and the polarized beam. The image forming apparatus provides an image to a refractive body.

The projection subsystem includes a projection lens assembly. The projection lens assembly receives an image from the refracting body and provides an image projection beam having a luminous flux level.

According to one aspect, the projection subsystem has a portability efficacy including a volume of less than 14 cm < 3 > and a thickness of less than 14 mm.

Figure 1 is a graph 100 illustrating a qualitative measure of portability for projection subsystems.
Figure 2 shows a projection subsystem.
Figure 3a illustrates a projection subsystem comprising an anamorphic optical device.
Figure 3b shows a projection subsystem that includes a non-uniform surface on the refracting body;
Figure 4 is a perspective view of the projection subsystem of Figure 3a.
Figures 5A and 5B show portions of a projection subsystem including a blue blocking filter.
Figures 5C and 5D illustrate portions of a projection subsystem that include a polarizing filter that changes image contrast.
Figure 6 shows a projection subsystem with a plate heat sink.
Figure 7 shows a projection subsystem including light recirculation.
Figure 8 shows a projection subsystem including an enclosure;
9 is a perspective view of a projection subsystem;
10A is a view showing a light emitting diode;
10B shows an image formed with light emitted by the light emitting diode of Fig. 10A through an optical system; Fig.
11A, 11B, 11C, and 11D illustrate examples of mounting optical components in a projection subsystem;
Figures 12A and 12B illustrate alternative embodiments of the projection subsystem.

For mobile applications, it is desirable to project an image with a diagonal size of 12 cm or greater under ambient lighting conditions, which generally requires at least a 3 lumen flux and at least a 30: 1 contrast ratio for good readability something to do. Additional desired features to provide good image quality include multiple resolvable pixels, wide color gamut, and image uniformity.

For mobile applications, "Portability" is defined as a combined measure of the small size of the projection subsystem, high power efficiency, and light output. Figure 1 is a graph 100 illustrating two aspects of portability for projection subsystems. The term "projection subsystem" refers to a light source, an image forming apparatus, and associated refractive or reflective optical components, for example, a lens, mirror, or beam splitter used to provide a projected optical image It says. The vertical axis 102 represents the power efficiency of the projection subsystem in units of lumens for one watt of power applied to the light source. The horizontal axis 104 represents the volume of the projection subsystem. The portability effectiveness 108 increases as the efficiency increases and increases as the volume decreases. The projection subsystem has increased portability when the power efficiency is higher and the volume is smaller.

Required features for the projection subsystem include high levels of luminous flux in the projected image, large screen size, high contrast, large pixel content, and wide color gamut. Figure 1 illustrates one way to compare some of these features for different optical systems. As described in the presently disclosed embodiments, a projection subsystem with an incoherent light source can provide a useful combination of required features.

As shown in FIG. 1, exemplary conventional projection subsystems A, C, D, and E are evaluated for power efficiency and magnitude and mapped onto graph 100. Subsystems A and C are generally superior to D and E in terms of power efficiency and size, but suffer from the disadvantages of high cost, low image quality due to laser speckle, and potential eye safety problems, especially under electrical or mechanical defect conditions. A coherent laser light source is used. Although subsystems D and E use non-coherent LED light sources that can overcome the disadvantages of laser-based systems, they have the disadvantage of being relatively large or power-efficient, or both, do. The exemplary projection subsystem of the present invention is represented on the graph 100 as a projection subsystem B that uses a non-coherent light source and is smaller in size and more efficient than subsystems D and E.

The ambient illumination level in the projection environment does not decrease when the projector design is miniaturized or shrunk. A sufficient projection power output level is required to provide a sufficiently bright projection image to a group of viewers in the presence of ambient light. For example, if the size of the light emitting source is reduced and if the same power level is applied to a smaller light emitting source, it may cause overheating in the face of increased temperature rise in a smaller light emitting source. There is a need to optimize the optical efficiency of the projector optical system in order to reduce the power level to avoid overheating of the small emitter without reducing the speed of the projected image output. Although a high power solid state laser capable of efficiently producing highly collimated coherent light can enhance the output efficiency, the use of coherent light can create speckle and reduce the projected image quality. In addition, the use of laser light causes concern about eye safety, especially under electrical or mechanical defect conditions.

As illustrated in the embodiments described below, the optical components are assembled in an improved combination to achieve the required high luminous flux levels with low power levels in the small projection subsystem. The use of coherent light sources is avoided. The portability effectiveness of the projection subsystem is improved. In particular, much of the optical loss that typically occurs when light passes through air between conventional projector optics components is avoided.

The projection subsystem disclosed herein can operate in the region 110 in the graph 100 with high portability. Region 110 is limited to a volume of 14 cm3 or less for one watt and an efficiency of 3.8 lumens or more.

Another measure of portability is the thickness of the projection subsystem along the thinnest axis. The projection subsystem is best suited for use in pocket portable devices when the projection subsystem has a thickness of less than 14 mm along the thickness axis. Another mode of portability is the speed of light. The projection subsystem is best suited for use in pocket portable devices when the luminous flux is at least three lumens.

FIG. 2 illustrates the projection subsystem 200. FIG. The projection subsystem 200 is useful for projecting still or video images from miniature electronic systems such as cellular telephones, personal digital assistants (PDAs), and global positioning system (GPS) receivers. The projection subsystem 200 receives power and image data from an embedded small electronic system (not shown in FIG. 2). The projection subsystem 200 is useful as a component of a small projector accessory for displaying computer video. The projection subsystem 200 is useful for systems that are small enough to be carried in a pocket of clothes, such as a shirt pocket, when not in use. The image projected by the projection subsystem 200 may be projected onto a reflective projection screen, a brightly colored wall, a whiteboard or paper sheet, or other known projection surface. The projection subsystem 200 may be embedded in, for example, a portable computer, such as a laptop computer, or a mobile phone.

The projection subsystem 200 includes a light engine 202. The light engine 202 provides a light beam 204. The light engine includes a condenser lens 206, a collimator 208 and a solid state light emitter 210. According to one aspect, the focusing lens 206 includes a hyperhemispheric ball lens. According to one aspect, a hyper hemispherical ball lens is arranged as taught in U.S. Patent Application Publication No. 2007/0152231.

The solid state light emitters 210 receive power 212 having a power level. The solid state light emitters 210 are thermally coupled to the heat sink 214. The solid state light emitters provide an emitter light beam with a predetermined emitter light beam level. According to one aspect, the light beam 204 comprises non-coherent light. According to another aspect, the light beam 204 includes illumination that is a partially focused image of the solid state light emitters 210. [ According to another aspect, the solid state light emitters 210 include one or more light emitting diodes (LEDs). According to another aspect, the focusing lens 206 includes a hyper hemispherical ball lens. According to another aspect, the collimator 208 includes a first non-faceted side that receives a first non-collimated beam and a second passive side that emits the collimated beam. And a second Fresnel lens having a second non-passive face for substantially directly receiving the collimated beam and a second passive face for emitting an output beam, And includes a focusing unit. According to another aspect, the solid state light emitters 210 may be arranged as shown in U.S. Provisional Patent Application No. 60 / 820,883. According to another aspect, light engine 202 may be arranged as shown in U. S. Patent Nos. 60 / 820,887, 60 / 820,888, 60 / 821,032, 60 / 838,988.

The projection subsystem (200) includes a refractor (220). The refracting element 220 receives the light beam 204. Refractor 220 provides a polarized beam 222. Refractor 220 includes an inner polarizing filter 224. One polarization component of the light beam 204 is reflected by the inner polarization filter 224 to form a polarized beam 222. According to one aspect, refractors are disclosed in U.S. Patent Application Publication No. 2007/0023941 A1 to Duncan et al., U.S. Patent Application Publication No. 2007/0024981 A1 to Duncan et al., U.S. Patent Application Publication 2007/0085973 Al to Duncan et al, And Duncan, U. S. Patent Application Publication No. 2007/0030456. Refractor 220 includes a first outer lens surface 226 and a second outer lens surface 228. According to one aspect, outer lens surfaces 226 and 228 have curved lens surfaces and have a non-zero lens power. According to another aspect, the outer lens surface 226 includes a convex lens surface that is useful for maintaining a small volume for the projection subsystem 200. According to another aspect, outer lens surfaces 226 and 228 are flat. According to one aspect, refractor 220 includes plastic resin material bodies 230 and 232 on opposing sides of inner polarizing filter 224. According to another aspect, the inner polarizing filter 224 comprises a multilayer optical film. According to another aspect, refractor 220 includes a multifunctional optical component that functions as a lens as well as a polarizing beam splitter. By combining the polarizing beam splitter and lens functions in a multifunction refractometer, it prevents loss that would otherwise occur at the air interface between the separated beam splitter and the lens.

The projection subsystem 200 includes an image forming device 236. The image forming device 236 receives image data on an electrical input bus 238. The image forming device 236 receives the polarized beam 222. The image forming device 236 selectively reflects the polarized beam 222 according to the image data. The image forming device 236 provides an image 240 having polarized light that is rotated with respect to the polarization of the polarized beam 222. The image forming device 236 provides an image 240 to the refractor 220. [ The image 240 passes through the inner polarizing filter 224. According to one aspect, the image forming device 236 includes a liquid crystal on silicon (LCOS) device.

The projection subsystem 200 includes a projection lens assembly 250. The projection lens assembly 250 includes a plurality of lenses schematically represented by reference numerals 252, 254, 256, 258, The projection lens assembly 250 receives the image 240 from the refracting element 220. The projection lens assembly 250 provides an image projection beam 262 with a projection beam suitable for viewing. According to one aspect, the projection beam is greater than three lumens. According to another aspect, the ratio of the projection beam to the power level is at least 3.8 lumens per watt. According to another aspect, the ratio of the projection beam to the power level is at least 7 lumens per watt. According to another aspect, the ratio of the projection beam to the power level is at least 10 lumens per watt. According to another aspect, the light collection efficiency ratio is at least 38.5%. The light collection efficiency ratio is defined as the ratio of the polarized luminous flux impinging on the active surface of the image forming device 236 to the luminous flux emitted from the non-polarized solid state light emitters 210.

According to another aspect, the projection subsystem 200 has a power level of 3.6 watts or less. According to another aspect, the projection subsystem 200 has a volume of less than 14 cm < 3 >. According to another aspect, the projection subsystem 200 has a thickness of less than 14 mm.

According to another aspect, the projection subsystem 200 has an F number (F number) that is less than 2.4. According to another aspect, the projection subsystem has an ANSI contrast ratio of at least 30: 1. According to another aspect, the projection subsystem has an ANSI contrast ratio of at least 50: 1. According to another aspect, the projection subsystem has an on / off contrast ratio of at least 100: 1.

FIG. 3A shows a projection subsystem 300. FIG. The projection subsystem 300 is similar to the projection subsystem 200 except that the unequal optics 302 is included in the projection subsystem 300. The same reference numerals as those used in Fig. 2 denote the same or similar features. In another aspect, the projection subsystem 300 is similar to the projection subsystem 200. The non-uniform optical device 302 changes the aspect ratio of the light beam 304. The unequal optics 302 changes the shape of the light beam to adapt the first aspect ratio in the light engine 202 to a different second aspect ratio in the refractor 220. [ According to one aspect, the first aspect ratio is 1: 1 and the second aspect ratio is 16: 9. According to another aspect, the first aspect ratio is 1: 1 and the second aspect ratio is 4: 3. According to one aspect, the second aspect ratio is matched to the aspect ratio of the image forming apparatus 236. [ According to one aspect, the unequal optical device 302 comprises an unequal lens as shown in Fig. 3A. According to another aspect shown in FIG. 3B, the unequal surface 306 provided on the refracting element 320 serves as an unequal optical device. In another aspect, refractor 320 is similar to refractor 220 of FIG.

According to another aspect, the polarizing filter may be located at position 330 or 332 in Figure 3A. The polarizing filter at position 330 or 332 improves the optical contrast ratio of optical subsystem 300. According to one aspect, the polarizing filter located at locations 330 and 332 comprises a multilayer optical film.

Figure 4 shows a perspective view of the projection subsystem 300 of Figure 3. The projection subsystem 300 has a thickness 402. The projection subsystem 300 has a cross-sectional area 400, shown as a stippled plane perpendicular to the thickness 402. The cross-sectional area 400 includes the area of the components 206, 208, 236, 220, 250, 302 and the area of the intervening air space between the components that carry useful light. The projection subsystem 300 has a volume that is a mathematical product of the thickness 402 and the cross-sectional area 400.

Figures 5A and 5B illustrate portions of a projection subsystem 500, 510 that are similar to the projection subsystem 200 or 300. The projection subsystem 500 includes a filter 502. The filter 502 is adjacent to the collimator 208. According to one aspect, the filter 502 includes an optical component that is separate from the collimator 208. According to another aspect, the filter 502 includes a filter layer on the collimator 208. According to one aspect, the collimator 208 is between the filter 502 and the lens 206 as shown in FIG. 5A. According to another aspect shown in FIG. 5B, the filter 504 is between the collimator 208 and the lens 206. Filters 502 and 504 include blue blocking filters that also block ultraviolet (UV) radiation. The blue blocking filter blocks blue and ultraviolet light at wavelengths that tend to degrade the refractive optical device, while passing a portion of the blue spectrum that desires to be present in the projected image. The filter 502 or 504 prevents unwanted light from reaching the refractor 220.

Figures 5c and 5d show portions of the projection subsystem 520, 540 that are similar to the projection subsystem 200 or 300. The projection subsystem 520 includes a filter 522. The filter 522 is positioned between the refractor 220 and the projection lens assembly 250. The projection subsystem 540 includes a refractor 220A that includes a filter 542 that is adjacent to the polarizing filter 224. The filter 542 is positioned between the polarizing filter 224 and the plastic resin body 230. Filters 522 and 542 include polarizing filters. Polarizing filters 522 and 542 increase the contrast of the projected image. According to one aspect, the projection subsystem according to FIG. 5d is described in "Polarizing Beam Splitters Incorporating Reflective and Absorptive Polarizers and Image Display Systems Thereof", entitled "Polarizing Beam Splitter Including Reflective Polarizers and Absorbing Polarizers" U.S. Patent Application No. 11 / 457,599.

Figure 6 shows that the projection subsystem 600 includes a plate heat sink 602 while the projection subsystem 300 of Figure 4 includes a heat sink 214 having projections such as fins or pins , Which is similar to the projection subsystem 300 of FIG. 4. In another aspect, the projection subsystem 600 is similar to the projection subsystem 300. According to one aspect, the plate heat sink 602 may include a lower plate surface 604 (not shown) exposed on the outer package surface of a pocket portable electronic package such as a cellular phone, a personal digital assistant (PDA), a positioning system ). According to another aspect, the plate heat sink 602 is in thermal contact with other elements of the electronic device to dissipate heat. According to another aspect, in use, the lower plate surface 604 may be disposed in contact with the accessory external heat sink for extended use.

Figure 7 illustrates the projection subsystem 300 of Figure 3a except that the projection subsystem 700 includes a polarizing film 702 disposed along the optical path between the condenser lens 206 and the refractor 220. [ Lt; RTI ID = 0.0 > 700 < / RTI > According to one aspect, the polarizing film 702 is disposed between the collimator 208 and the refractor 220 as shown in FIG. The polarizing film 702 reflects the polarized light back toward the reflective surface of the solid state light emitter 210 to provide light recirculation. The inclusion of the polarizing film 702 increases the luminous flux of the projection subsystem. According to one aspect, polarization recycling is as described in U.S. Patent Application No. 11 / 772,609, filed July 2, 2007.

Figure 8 shows a projection subsystem 800 that is similar to the projection subsystems of Figures 3A and 7. The projection subsystem 800 includes an enclosure 802 that surrounds at least portions of the optical components 206, 208, 702, 302, 220 and protects the optical component surfaces from contaminants and moisture. According to one aspect, the enclosure 802 may include an air filter 806. The air filter 806 restricts the flow of air, filters the contaminants, and makes the pressure equal between the interior of the enclosure 802 and the ambient atmosphere. According to one aspect, the air filter 806 includes a dessicant 808 to reduce moisture within the enclosure 802. [ According to another aspect, the enclosure 802 provides mechanical mounting for the optical component.

Enclosure 802 is coupled to lens assembly guide tube 804. The projection lens assembly 250 is slidably mounted in the guide tube 804. The projection lens assembly 250 includes an actuation lever 810 that can be mechanically actuated to move the position of the projection lens assembly 250 relative to the image forming device 236. Movement of the projection lens assembly 250 includes focus adjustment. According to one aspect, the projection lens assembly 250 is closely fitted to the guide tube 804 to provide a seal that prevents contaminants from entering the enclosure 802. According to another aspect, one or more O-rings (not shown) are provided between the projection lens assembly and the guide tube 804 to provide a seal. According to another aspect, bellows (not shown) are provided between the end of the projection lens assembly 250 and the guide tube 804 to provide a seal.

FIG. 9 shows a perspective view of a projection subsystem 900 similar to the projection subsystem shown in FIG. The projection subsystem 900 includes a solid state light emitter (not shown in FIG. 9) connected to a power source by electrical leads 902, 904. The solid state light emitters are thermally coupled to the heat sink 906. The projection subsystem 900 includes a condenser lens 908. The projection subsystem 900 includes an image forming device 912, a refracting element 914, and a projection lens 916.

FIG. 10A illustrates a light emitting diode 1000 serving as an exemplary solid state light emitter, such as the solid state light emitter 210 of FIG. Light emitting diode 1000 is connected to power through bond wires 1002 and 1004. The light emitting diode 1000 includes light emitting regions 1008, 1010, 1012, 1014, and 1016. Other regions of the light emitting diode 1000, such as regions 1018, 1020, 1022, 1024, 1026, 1028, include dark regions that include an electrical conductor and do not generate light. Therefore, the image of the light emitting diode 1000 is a pattern of a region that generates light and a region that does not generate light. For use in projection, an image with a relatively uniform brightness, such as that shown in Fig. 10B, is required. According to one aspect, providing uniform brightness is as taught in U. S. Patent Application Publication 2007/0153397, entitled " PROJECTION SYSTEM WITH BEAM HOMOGENIZER ".

Figure 11A shows an example of mounting an optical component in a projection subsystem. The molded component 1100 includes an optical portion 1102 along the optical axis 1104 and a mounting flange portion 1106 molded with the optical portion 1102 and a single structure. The optical portion 1102 includes a lens, but any of the optical components of the projection subsystem may be used in place of the lens. The molded component is molded from a refractive material such as a transparent plastic resin. The mounting flange portion 1106 has rims 1108 and 1110 shaped to match the flanges of adjacent molded components. The rims may be attached to each other by friction fit, snap fit, adhesive, thread, or other known attachment methods for plastic resin molded components.

FIG. 11B shows an example of mounting optical components in the projection subsystem. The optical component 1120 is captured in the grooves 1122 and 1124 of the matching halves of the mounting tube 1126. A number of optical components are mounted to the mounting tube. Mounting tube 1126 is assembled along parting line 1128. Optical portion 1120 includes a lens, but any of the optical components of the projection subsystem may be similarly mounted instead of a lens.

Figure 11C shows an example of mounting an optical component in a projection subsystem. The optical component 1130 is captured in the groove 1132 of the mounting channel 1134. The lid 1136 is secured to the mounting channel. A number of optical components are mounted to the mounting channel 1134. The mounting channel 1134 and the lid 1136 are assembled along the dividing line 1138. Optical portion 1130 includes a lens, but any of the optical components of the projection subsystem may be similarly mounted instead of a lens.

Figure 11d shows an example of a combination of shaped refractors 1150 (e.g., refractor 220 of Figure 2) with mounting flange rims 1152,1154, and 1156 similar to those shown in Figure 11a.

Figures 12A and 12B illustrate alternative embodiments of a projection subsystem with portability as described above. 12A illustrates a projection subsystem 1202 that includes a light engine 1204, an image forming device 1206, and a projection lens assembly 1208. As shown in FIG. The image forming apparatus 1206 includes a transmissive image forming apparatus. Figure 12B illustrates a projection subsystem 1222 that includes a light engine 124, an image forming device 1226, an unequal lens 1228, and a projection lens assembly 1230. [ Image forming device 1226 is a reflective image forming device, such as an array of deflectable mirror pixels, and does not require polarized light for its operation.

Yes

Constitute a projection subsystem similar to that of Figs. 7 and 9, with a refractometer similar to Fig. 3b. The solid state light emitters were fabricated using a conformal yellow phosphor produced by Cree, Inc. (4600 Durham Silicon Drive, NC 27703, USA) and a blue InGaN die with part number C450-EZ1000-S30000 It is a manufactured white LED. Coupling to a focusing lens and its LED is described in U.S. Patent Application Publication No. 2007/0152231. The collimator is a non-passive face that receives the non-collimated beam and a Fresnel lens that has a passive face that emits the collimated beam. The refractometer is a molded plastic polarizing beam splitter (PBS) as described in U.S. Patent Publication 2007/0024981. The reflective polarizing films, one of which is shown in PBS and the one shown as element 702 in FIG. 7, are commercially available under the tradename "VIKUITI" advanced polarizing film "; APF). The image forming device is an LCOS microdisplay with internal red, green, and blue filters, part number HX7007ATBFA, produced by Himax Display (Taiwan, No. 26 2F, Jianlian Road, Taiwan, 74445, Taiwan).

Measurements of dimensions and performance are summarized in the following table, where IEC stands for International Electrotechnical Commission.

Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims (1)

A solid-state incoherent light emitter - a solid-state incoherent light emitter, receiving a power level, being capable of being coupled to a heat sink, emitting light having a luminous flux level, A light engine for providing a light beam;
An image forming apparatus for receiving image data, at least receiving a component of a light beam, and providing an image;
And a projection lens assembly for receiving an image and providing an image projection beam having a projection beam level,
Wherein the ratio of the luminous flux to the power level is at least 3.8 lumens per watt and the projection subsystem volume is less than 14 cm < 3 >.

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