WO2012024850A1

WO2012024850A1 - Optical structure of led liquid crystal projector with single polarization converter

Info

Publication number: WO2012024850A1
Application number: PCT/CN2010/077580
Authority: WO
Inventors: 陆祖康; 吴碧珍; 田宝龙; 倪旭翔
Original assignee: 浙江金成科技发展有限公司
Priority date: 2010-08-27
Filing date: 2010-10-08
Publication date: 2012-03-01
Also published as: CN102004321A

Abstract

An optical structure of LED liquid crystal projector with a single polarization converter comprises an illumination optical axis and an imaging optical axis which are perpendicular to each other. The LED (101), the collimation lens (102), the single transmissive polarization converter (103), the lens array (104) and the relay optics (105) are sequentially arranged along the illumination optical axis; the LCOS liquid crystal screen (106), PBS (107), and the projection lens (108) are sequentially arranged along the imaging optical axis. The optical structure can also comprises two illumination optical axes and one imaging optical axis. The LED (201), the collimation lens (202) and the single reflective polarization converter (203) are sequentially arranged along the first illumination optical axis; the lens array (204) and the relay optics (205) are sequentially arranged along the second illumination optical axis; the LCOS liquid crystal screen (206), PBS (207) and the projection lens (208) are sequentially arranged along the imaging optical axis; the first illumination optical axis and the imaging optical axis are parallel to each other and both of them are perpendicular to the second illumination optical axis. The single transmissive polarization converter (103) or the single reflective polarization converter (203) can realize the polarized light conversion and has the advantages of small volume, high light efficiency, low cost, and simple processing and assembling.

Description

Optical structure of LED liquid crystal projector with single polarization converter

This invention relates to the optical construction of LED liquid crystal projectors, and more particularly to the optical construction of LED liquid crystal projectors having a single polarization converter.

Background technique

The liquid crystal projector is a widely used optoelectronic product. At present, the common liquid crystal projector uses a metal halogen tungsten lamp as a light source, although the brightness is high, but the volume is large. Such a liquid crystal projector usually uses a polarization conversion system (PCS) to convert unpolarized light of a metal halogen lamp into polarized light to improve the utilization of light energy. PCS typically includes a row of cube prism arrays and a double row lens array. The cube prism array is bonded together by n cube prisms. Since the unpolarized light passes through the cube prism, the diameter of the exit beam will increase to (n+l)/n times the diameter of the incident beam, in order not to significantly increase the beam exit. The diameter, n is usually larger, such as 6 or more, so the cube prism array is complicated to manufacture, high in cost, and large in volume. The second row of lens arrays of the double row lens array is generally located on the focal plane of the first row of lens arrays, and the plurality of thin beams split by the first row of lenses are superimposed and imaged at infinity, and the relay light is formed on the surface of the liquid crystal screen. Form uniform illumination. Another important role of the double row lens array in the PCS is to provide a matching environment for the beam splitting of the cube prism array to improve the transversal efficiency of the PCS. Therefore, the design and installation of the lens array must be considered in conjunction with the cube prism array. Due to the precise adjustment of the relative positions of the two rows of lens arrays and the cube prism array in the assembly, it is time consuming and laborious, and the double row lens array also causes the projector to be bulky.

With the popularization and application of LED light sources, liquid crystal projectors using LEDs as light sources have also been gradually promoted. If the polarization conversion system PCS of the aforementioned halogen lamp liquid crystal projector is still employed in the LED liquid crystal projector, the volume and cost of the projector will be difficult to reduce. In addition, due to the large light-emitting area of LEDs, it is difficult to borrow mature PCS technology. To date, no products have been seen for tiny projectors that use polarization conversion technology. Therefore, how to transplant polarization conversion technology into micro-miniature LED liquid crystal projectors has become a trend of new technologies.

Summary of the invention

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical structure of a LED liquid crystal projector having a single polarization converter which is small in size, high in luminous efficiency, low in cost, and simple to process and assemble.

In order to achieve the above object, the present invention has the following two technical solutions.

plan 1

Optical structure of an LED liquid crystal projector with a single polarization converter, including an illumination optical axis and an imaging optical axis, sequentially placing LEDs on the illumination optical axis, a collimating mirror, a single transmissive polarization converter, a lens array Column and relay light group, LCOS liquid crystal screen, PBS and projection lens are sequentially placed on the imaging optical axis, and the illumination optical axis is perpendicular to the imaging optical axis; the unpolarized light emitted by the LED is collimated by the collimating mirror, and is incident to a single transmission. A polarization converter converts unpolarized light into polarized light by a single transmissive polarization converter and is incident on the lens array. The beam is shaped by the lens array and passed through the relay group to the PBS. The PBS reflects the polarized light on the LCOS LCD screen. . After the polarized light is modulated by the LCOS liquid crystal screen, the polarization direction changes by 90 degrees, and then is reflected to the PBS, and transmitted to the projection lens through the PBS, and the image of the LCOS liquid crystal screen is projected onto the projection screen by the projection lens.

The single transmissive polarization converter can be glued by a right-angle prism and an oblique prism, and a polarizing beam splitting film is coated on the bonding surfaces of the two, and a 1/2 wave plate is pasted on the exit surface of the right-angle prism to be incident. All of the unpolarized light is converted into S-polarized light; or a 1/2 wave plate is pasted on the exit surface of the oblique prism, and all of the incident unpolarized light is converted into P-polarized light.

The single transmissive polarization converter described above may also be composed of two 45-degree parallel plates, wherein the first plate is a polarization beam splitter and the second plate is a full mirror. Placing a 1/2 wave plate vertically between the ends of the two plates to convert all of the incident unpolarized light into P-polarized light; or vertically pasting the 1/2 wave plate above the end of the first plate, the incident Unpolarized light is all converted to S-polarized light.

Scenario 2

An optical structure of an LED liquid crystal projector having a single polarization converter, comprising two illumination optical axes and an imaging optical axis, wherein the LEDs, the collimating mirrors and the single reflective polarization converters are sequentially placed on the first illumination optical axis. The lens array and the relay light group are sequentially placed on the second illumination optical axis, and the LCOS liquid crystal screen, the PBS and the projection lens are sequentially placed on the imaging optical axis, and the first illumination optical axis and the imaging optical axis are parallel to each other, and both are perpendicular to the second Illumination optical axis; the unpolarized light emitted by the LED is collimated by the collimating mirror, incident on a single reflective polarization converter, and the unpolarized light is converted into polarized light by a single reflective polarization converter and reflected to the lens array, the beam After being shaped by the lens array, the relay light group reaches the PBS, and the PBS reflects the polarized light on the LCOS liquid crystal panel. After the polarized light is modulated by the LCOS liquid crystal panel, the polarization direction changes by 90 degrees, and then is reflected to the PBS, and transmitted to the projection lens through the PBS, and the image of the LCOS liquid crystal panel is projected onto the projection screen by the projection lens.

The single reflective polarization converter described above may be formed by bonding a right-angle prism and an oblique prism, and a polarizing beam splitting film is coated on the bonding surfaces of the two, and a 1/2 wave plate is pasted on the exit surface of the oblique prism. All of the incident unpolarized light is converted into S-polarized light; or a 1/2 wave plate is pasted on the exit surface of the right-angle prism, and all of the incident unpolarized light is converted into P-polarized light.

The invention can convert all unpolarized light emitted by the LED into polarized light, thereby effectively improving the projector The light energy utilizes efficiency and brightness, is small in size, low in cost, and simple in processing and assembly. DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view showing the optical structure of an LED liquid crystal projector having a single polarization converter according to a first aspect of the present invention.

Figure 2 is a schematic diagram of a first single transmissive polarization converter.

Figure 3 is a schematic illustration of a second single transmissive polarization converter.

Figure 4 is a schematic diagram of a third single transmissive polarization converter.

Figure 5 is a schematic illustration of a fourth single transmissive polarization converter.

Figure 6 is a schematic view showing the optical structure of an LED liquid crystal projector having a single polarization converter of the second aspect of the present invention.

Figure 7 is a schematic diagram of a first single reflective polarization converter.

Figure 8 is a schematic illustration of a second single reflective polarization converter.

detailed description

Referring to Figure 1, the optical structure of an LED liquid crystal projector having a single polarization converter of Scheme 1, comprising an illumination optical axis and an imaging optical axis, sequentially placing a light source LED 101 on the illumination optical axis, a collimating mirror 102, a single transmissive polarization The converter 103, the lens array 104 and the relay light group 105 sequentially place an LCOS liquid crystal panel 106, a PBS (polarization beam splitter) 107 and a projection lens 108 on the imaging optical axis, and the illumination optical axis is perpendicular to the imaging optical axis; After the unpolarized light is collimated by the collimating mirror 102, it is incident on a single transmissive polarization converter 103, and the unpolarized light is converted into polarized light by a single transmissive polarization converter 103, and incident on the lens array 104, the beam is made up of a lens The array 104 is shaped to pass through the relay light group 105 to the PBS 107, and the PBS 107 reflects the polarized light on the LCOS liquid crystal panel 106. After the polarized light is modulated by the LCOS liquid crystal panel 106, the polarization direction is changed by 90 degrees, and then reflected to the PBS 107, and transmitted to the projection lens 108 via the PBS 107, and the image of the LCOS liquid crystal panel 106 is projected onto the projection screen 109 by the projection lens 108.

The single transmissive polarization converter 103 is made of a right-angle prism 103A and an orthorhombic prism 103B, and a polarizing beam splitting film is plated on both surfaces thereof, as shown in FIG. 2, and is emitted from the rhombic prism 103B. The 1/2 wave plate 103C is pasted on the surface, and at this time, all of the incident unpolarized light is converted into P-polarized light. Alternatively, as shown in Fig. 3, a 1/2 wave plate 103C may be attached to the exit surface of the right-angle prism 103A to convert all of the incident unpolarized light into S-polarized light.

The single transmissive polarization converter 103 described above may also be composed of two flat plates arranged at 45 degrees in parallel, wherein the first plate 103D is a polarization beam splitter and the second plate 103E is a full mirror. As shown in Figure 4, the 1/2 wave plate 103C is vertically pasted between the ends of the two plates, and all the incident unpolarized light is incident. Converted to P-polarized light; or as shown in FIG. 5, the 1/2-wave plate 103C is vertically pasted on the end of the first flat plate 103D, and all of the incident unpolarized light is converted into S-polarized light. Referring to FIG. 6, the optical structure of the LED liquid crystal projector with a single polarization converter of scheme 2 includes two illumination optical axes and one imaging optical axis, and sequentially placing the light source LEDs 201 sequentially on the first illumination optical axis, collimating The mirror 202 and the single reflective polarization converter 203, the lens array 204 and the relay light group 205 are sequentially placed on the second illumination optical axis, and the LCOS liquid crystal panel 206, the PBS 207 and the projection lens 208 are sequentially placed on the imaging optical axis, first The illumination optical axis and the imaging optical axis are parallel to each other and are perpendicular to the second illumination optical axis; the unpolarized light emitted by the LED 201 is collimated by the collimating mirror 202, and then incident on the single reflective polarization converter 203 by a single reflection type The polarization converter 203 converts the unpolarized light into polarized light and reflects it to the lens array 204. The beam is shaped by the lens array 204 and passed through the relay light group 205 to the PBS 207. The PBS 207 reflects the polarized light on the LCOS liquid crystal panel 206. After the polarized light is modulated by the LCOS liquid crystal panel 206, the polarization direction changes by 90 degrees, is reflected to the PBS 207, is transmitted to the projection lens 208 via the PBS 207, and the image of the LCOS liquid crystal panel 206 is projected onto the projection screen 209 by the projection lens 208.

The single reflective polarization converter 203 can be glued by a right angle prism 203A and a square prism 203B, and a polarizing beam splitting film is plated on the glued surfaces of the two, as shown in FIG. 7, and is emitted from the oblique prism 203B. The 1/2 wave plate 203C is pasted on the surface, and all of the incident unpolarized light is converted into S-polarized light; or as shown in FIG. 8, the 1/2 wave plate 203C is pasted on the exit surface of the right-angle prism 203A, and the incident non- The polarized light is all converted into P-polarized light.

Claims

~ 1. The optical structure of an LED liquid crystal projector with a single polarization converter, comprising an illumination optical axis and an imaging optical axis, which are sequentially placed on the illumination optical axis (101), a collimating mirror (102), a single transmission a polarization converter (103), a lens array (104) and a relay light group (105), which sequentially place an LCOS liquid crystal panel (106), a PBS (107) and a projection lens (108) on the imaging optical axis, and an illumination optical axis Vertically to the imaging optical axis; the unpolarized light emitted by the LED (101) is collimated by the collimating mirror (102) and incident on a single transmissive polarization converter (103), which is replaced by a single transmissive polarization converter (103) The polarized light is converted into polarized light and incident on the lens array (104). The beam is shaped by the lens array (104) and passed through the relay light group (105) to the PBS (107), and the PBS (107) reflects the polarized light to the LCOS liquid crystal. Screen (106). After the polarized light is modulated by the LCOS liquid crystal panel (106), the polarization direction changes by 90 degrees, and then is reflected to the PBS (107), transmitted to the projection lens (108) via the PBS (107), and the LCOS liquid crystal panel is projected by the projection lens (108). The image of 106) is projected onto the projection screen (109).

2. The optical structure of an LED liquid crystal projector having a single polarization converter according to claim 1, wherein the single transmissive polarization converter (103) comprises a right angle prism (103A) and an oblique prism (103B). Glued, a polarizing beam splitting film is coated on both bonding surfaces, and a 1/2 wave plate (103C) is attached to the exit surface of the right-angle prism (103A) to convert all incident unpolarized light into S-polarized light; A 1/2 wave plate (103C) is attached to the exit surface of the orthoptical prism (103B), and all of the incident unpolarized light is converted into P-polarized light.

3. The optical structure of an LED liquid crystal projector having a single polarization converter according to claim 1, wherein the single transmissive polarization converter (103) is composed of two flat plates arranged at 45 degrees in parallel, wherein the first block The flat plate (103D) is a polarizing beam splitter and the second plate (103E) is a full mirror. Paste a 1/2 wave plate (103C) vertically between the ends of the two plates to convert all of the incident unpolarized light into P-polarized light; or vertically paste 1/2 above the end of the first plate (103D) The wave plate (103C) converts all incident unpolarized light into S-polarized light.

4. An optical structure of an LED liquid crystal projector having a single polarization converter, comprising: two illumination optical axes and an imaging optical axis, wherein the LEDs (201) are placed in sequence on the first illumination optical axis, the collimating mirror (202) and a single reflective polarization converter (203), the lens array (204) and the relay light group (205) are sequentially placed on the second illumination optical axis, and the LCOS liquid crystal screen (206) is sequentially placed on the imaging optical axis. PBS (207) and projection lens (208), the first illumination optical axis and the imaging optical axis are parallel to each other and are perpendicular to the second illumination optical axis; the unpolarized light emitted by the LED (201) is aligned by the collimating mirror (202) Straight back, incident on a single reflective polarization converter (203), converted into polarized light by a single reflective polarization converter (203), and reflected to the lens array (204), the beam by the lens array (204) Relayed after shaping The light group (205) reaches the PBS (207), and the PBS (207) reflects the polarized light on the LCOS liquid crystal panel (206). After the polarized light is modulated by the LCOS liquid crystal panel (206), the polarization direction changes by 90 degrees, and then is reflected to the PBS (207), transmitted to the projection lens (208) via the PBS (207), and the LCOS liquid crystal panel is projected by the projection lens (208) ( The image of 206) is projected onto the projection screen (209).

5. The optical structure of an LED liquid crystal projector having a single polarization converter according to claim 4, wherein the single reflective polarization converter (203) comprises a right angle prism (203A) and an oblique prism (203B). Gluing, a polarizing beam splitting film is coated on both bonding surfaces, and a 1/2 wave plate (203C) is attached to the exit surface of the oblique prism (203B) to convert all incident unpolarized light into S-polarized light; Alternatively, a 1/2 wave plate (203C) is attached to the exit surface of the right-angle prism (203A), and all of the incident unpolarized light is converted into P-polarized light.