KR100667759B1 - Illuminating unit and projection type image display apparatus employing the same - Google Patents

Abstract

Disclosed are a lighting unit having a structure that enables to increase the light condensing efficiency of illumination light and to illuminate light having a specific polarization, and an image projection apparatus employing the same.

The disclosed lighting unit comprises: a first and second light source units including a collimator having a reflective surface and one or a plurality of optical modules positioned in the reflective surface and having a light source for irradiating light of a predetermined wavelength; First and second polarization recovery integrators for converting the light illuminated in each of the first and second light source units into uniformly uniform polarized light; And a polarization beam splitter for converting the propagation path according to the polarization component of the incident light so that the light incident from different positions travels in the same path.

In addition, the disclosed image projection device and the above lighting unit; An image forming element for forming an image corresponding to an image signal input from the uniform light emitted from the polarizing beam splitter; And a projection lens unit configured to enlarge and project the image formed on the image forming element on the screen.

Description

Lighting unit and projection type image display apparatus employing the same}

1 is a schematic view showing an optical arrangement of a conventional lighting unit and a projection apparatus employing the same.

2 is a schematic view showing a lighting unit according to a first embodiment of the present invention.

3 is a perspective view showing an embodiment of the optical module shown in FIG.

4 is a side view of FIG. 3;

FIG. 5 is a schematic perspective view illustrating a light source unit in which the optical module of FIG. 2 is arrayed. FIG.

6 is an exploded perspective view showing the first and second polarization recovery optical integrator shown in FIG.

7 is a schematic view showing a lighting unit according to a second embodiment of the present invention.

FIG. 8 is a schematic view showing a trichroic prism according to a first embodiment of the composite prism shown in FIG. 7;

9 is a schematic diagram illustrating an X-cube prism according to a second embodiment of the composite prism of FIG. 7.

10 is a schematic view showing an optical arrangement of an image projection apparatus according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

110, 210, 301 ... 1st light source unit 120, 220, 302 ... 2nd light source unit

130, 231 ... optical module 141 ... first condensing lens unit

Second condensing lens unit

150, 303 ... First Polarization Recovery Integrator

160, 304 ... 2nd Polarization Recovery Integrator

171 Aperture 173 Integrator Rod

175 ... 1/4 waveplate 177 ... polarizer

180, 280, 305 ... polarized beam splitter 190, 290 ... relay lens unit

235 Synthetic Prism 236 Tricroic Prism

237 ... X Cube Prism 300 ... Lighting Unit

310 beam splitter 320 image forming element

330 Projection Lens Unit 340 Screen

The present invention relates to an illumination unit for illuminating light and an image projection apparatus employing the same, and more particularly, to an illumination unit having a structure capable of illuminating light having a specific polarization while increasing the condensing efficiency of the illumination light and an image employing the same. It relates to a projection device.

In general, the lighting unit is composed of a light source for irradiating light in one direction, and an illumination optical system for transmitting a beam irradiated from the light source, an image forming device such as a liquid crystal display device or a digital micromirror device that does not have a light emitting capability by itself. It is widely used for an image projection apparatus or the like which implements an image by using.

Recently, a lighting unit and an image projecting device employing a small light emitting element such as a light emitting diode (LED) as a light source have been developed. On the other hand, this LED has a problem that the amount of light is very small compared to a metal halide lamp or a mercury lamp used as a general light source. Therefore, it is required to improve the light condensing efficiency for use in an image projector.

In this regard, Japanese Patent Laid-Open No. 2004-70017, published on March 4, 2004, discloses "the illumination optical system structure of the projection apparatus and the projection apparatus."

This disclosed projection apparatus has a first and a second illumination system (I) (II) for illuminating light of different polarization, respectively, as shown in FIG. 1, and in the first and second illumination systems (I) (II). A polarizing prism 21 for synthesizing the illuminated light and directing it in one direction, a total reflection prism 23 for converting a traveling path of light, and a light valve 25 provided on one side of the total reflection prism 23 to form an image. And a projection lens unit 27 for projecting the formed image onto the screen 29.

Here, the first illumination system (I) is to illuminate the light of the red, blue, and green wavelengths, respectively, the first to third LED light source (11) (12) (13) disposed at different positions and the first to third 3 is composed of a wavelength synthesizer 14 and a first and second lens arrays 15 and 16 to allow the light emitted from the 3 LED light sources 11, 12 and 13 to travel in the same path. And a polarization converting element 18 such that the light passing through the optical integrator 17 becomes light of one polarization. The second lighting system (II) has the same configuration as the first lighting system (I). However, the direction of polarization converted by the polarization conversion element 18 ′ of the second illumination system II has a direction different from the direction of polarization changed by the polarization conversion element 18 of the first illumination system I.

Therefore, light of one polarization irradiated by the first illumination system I passes through the polarization prism 21 and is directed toward the total reflection prism 23, and light of another polarization irradiated by the second illumination system II is the polarization. Reflected by the prism 21 and directed toward the total reflection prism 23.

In this way, the conventional projection apparatus configured has the advantage that the amount of light can be increased by using the first and second illumination systems I (II). However, in constructing the first and second illumination systems (I) (II), there is a problem in that the focusing loss is large because there is a lack of specific means for collimating the light illuminated from the first to third LED light sources. In addition, in the configuration of the first to third LED light source by combining a plurality of LED, there is a disadvantage that the array of the LED is difficult. In addition, when converting polarized light using a separate polarization conversion device, there is a disadvantage that the configuration of the illumination system is complicated.

Accordingly, the present invention has been made in view of the above-described problems, and the illumination unit having a structure to illuminate the collimating light while using a light source such as an LED, and to increase the condensing efficiency of the illumination light, and image projection employing the same. The purpose is to provide a device.

In order to achieve the above object, an illumination unit according to the present invention includes a first light source including a collimator having a reflective surface and a light source positioned in the reflective surface and having a light source for irradiating light of a predetermined wavelength. A unit; A first polarization recovery integrator for converting the light illuminated from the first light source unit into a uniform first polarized light; A second light source unit disposed at a position different from the first light source unit and including a collimator having a reflective surface and a light source positioned in the reflective surface and irradiating light of a predetermined wavelength; ; A second polarization recovery integrator for converting the light illuminated from the second light source unit into a uniform second polarized light; And a polarization beam splitter for converting the propagation path according to the polarization component of the incident light so that the light of the first and second polarized light incident at different positions travels in the same path.

In addition, the image projection device according to the present invention for achieving the above object, the above lighting unit; An image forming element for forming an image corresponding to an image signal input from the uniform light emitted from the polarizing beam splitter; And a projection lens unit configured to enlarge and project the image formed by the image forming element on a screen.

Hereinafter, with reference to the accompanying drawings will be described in detail a lighting unit and an image projection using the same according to a preferred embodiment of the present invention.

Referring to FIG. 2, the lighting units according to the first embodiment of the present invention may be disposed at different positions, respectively, and include first and second light source units 110 and 120 to generate and irradiate light, respectively. First and second polarization recovery integrators 150 and 160 which allow the light illuminated from each of the light source units 110 and 120 to be uniform and of predetermined polarization, and transmit or reflect incident light according to the polarization direction. It includes a polarizing beam splitter 180 so that the light irradiated from the first and second light source unit 110, 120 proceeds in the same path.

Each of the first and second light source units 110 and 120 includes one or a plurality of optical modules 130 for irradiating light having a predetermined wavelength.

3 and 4, the optical module 130 includes a collimator 131 and a light source 137 that irradiates light having a predetermined wavelength. The collimator 131 includes a parabolic first reflection surface 133 and a glass rod 132 having a rectangular cross section. The light source 137 is a small light source composed of at least one light emitting diode (LED), a laser diode, and the like, and the light emitting portion thereof is positioned at and around the focal point F of the first reflective surface 133. The first reflective surface 133 is formed by processing a portion of the glass rod 132 in the form of a parabolic surface and applying a reflective coating on the outer surface thereof. In addition, the collimator 131 is a second half formed by a reflective coating in a region other than the region G through which light directly irradiated from the light source 137 passes at the position facing the first reflection surface 133. A slope 134 may be further provided.

Therefore, light within a predetermined emission angle range among the light emitted from the light source 137 is reflected by the first reflection surface 133 and becomes parallel light. The parallel light passes through the light exit surface 135 after passing through the glass rod 132. On the other hand, since the light emitting portion of the light source 137 does not form a single point but has a predetermined area, the entire light emitting portion cannot be disposed at the focal position of the first reflective surface 133. Therefore, a part of the light irradiated by the light source 137 and reflected by the first reflection surface 133 proceeds to the second reflection surface 134. In this case, the second reflecting surface 134 reflects the incident light so as to be directed toward the light emitting surface 135.

The optical module 130 according to the present embodiment collimates the light illuminated by the light source 137 using the first reflecting surface 133 instead of the lens, thereby providing the principle of etendue caused by using the lens. It is possible to fundamentally solve problems such as a decrease in efficiency due to constraints.

In the above-described embodiment, the collimator 131 using the glass rod 132 has been described, but the present invention is not limited thereto. Instead, the collimator 131 may have a parabola on one side of a hollow optical tunnel (not shown) instead of the glass rod 132. It is also possible to form the reflective surface by forming the reflective surface and reflecting the inside thereof.

In addition, the lighting unit according to the present invention comprises a plurality of optical modules 130, as shown in Figure 5 in order to increase the light efficiency in configuring the first and second light source unit (110, 120). desirable. Referring to FIG. 5, the plurality of optical modules 130 may be classified into first to third optical module arrays 130R, 130B, and 130G according to wavelengths of light to be irradiated. Each of the first to third optical module arrays 130R, 130B, and 130G includes an optical module for irradiating light of red, blue, and green wavelengths. By simultaneously or sequentially driving the first to third optical module arrays 130R, 130B, and 130G, irradiating light with red, blue, and green wavelengths, and a combination thereof. It is possible to illuminate the full color light made up. Therefore, when applied to the image projection apparatus described later, it is possible to illuminate the color light without a color wheel (color wheel) device for color implementation.

In addition, the lighting unit according to the embodiment of the present invention is between the first light source unit 110 and the first polarization recovery integrator 150, the second light source unit 120 and the second polarization recovery integrator 160 Preferably, the apparatus further includes first and second condensing lens units 141 and 145 disposed therebetween. Each of the first and second condensing lens units 141 and 145 is composed of one or more lenses, and focuses and transmits the incident parallel light.

The first polarization recovery integrator 150 is disposed between the first light source unit 110 and the polarization beam splitter 180. The first polarization recovery integrator 150 converts unpolarized light illuminated by the first light source unit 110 to be uniform first polarized light, for example, S polarized light. In addition, the second polarization recovery integrator 160 is disposed between the second light source 120 and the polarization beam splitter 180 to uniformly light unpolarized light illuminated by the second light source unit 120. The light is converted to be light of one second polarized light, for example, light of P polarized light.

To this end, as shown in FIGS. 2 and 6, the first and second polarization recovery integrators 150 and 160 are respectively polarized beams from the first and second light source units 110 and 120. The aperture 171, the integrator rod 173, the quarter wave plate 175, and the polarizer 177 are sequentially arranged in the splitter 180 direction.

The integrator rod 173 is a cuboid-shaped glass rod, and totally internally reflects light incident at a predetermined angle using a difference in refractive index between the glass and the surrounding air so that light having a uniform light amount distribution in the cross section is emitted. Meanwhile, in addition to the glass rod, the integrator rod 173 may be configured as an optical tunnel having a hollow rectangular pillar shape having a total internal reflection coating.

The quarter wave plate 175 is provided at the output end 173b of the integrator rod 173 to change the polarization characteristic by delaying the phase of incident light. That is, when the incident light is linearly polarized light, the light is circularly polarized light, and when the incident light is circularly polarized light, the light is linearly polarized light. Therefore, when light of one specific polarization passes through the quarter wave plate 175 twice, it becomes light of another specific polarization. For example, when P-polarized light passes through the quarter wave plate 175 twice, it becomes S-polarized light. Similarly, in the case of S-polarized light, it becomes P-polarized light. Since the structure of the quarter wave plate 175 and the phase delay operation itself are well known, a detailed description thereof will be omitted.

The polarizer 177 is provided on one surface of the quarter wave plate 175, and transmits light of a specific polarization among incident light, and reflects light of another polarization. For example, light of P-polarized light is transmitted, and light of S-polarized light is reflected. Of course, by changing the lattice direction, the light of S-polarized light can be transmitted and the light of P-polarized light can be reflected.

The aperture 171 is provided at the incidence end 173a of the integrator rod 173, and transmits light incident from each of the first and second light source units 110 and 120, and transmits the inter The light incident from the greater rod 173 side is reflected back. For this purpose, a portion of the aperture 171 facing the integrator rod 173 is opened. In addition, it is preferable that the surface facing the integrator rod 173 is totally coated.

Hereinafter, the operation of the first polarization recovery integrator 150 will be described in detail. The unpolarized light illuminated by the first light source unit 110 passes through the aperture 171 and is incident on the integrator rod 173. The incident light becomes uniform light while passing through the integrator rod 173, and light of one polarized light, for example, S polarized light, passes through the polarizer 177 after passing through the quarter wave plate 175. To the polarizing beam splitter 180. On the other hand, light of another polarization, for example P-polarized light, is reflected by the polarizer 177, passes through the quarter wave plate 175, and passes through the integrator rod 173 to the aperture 171. To the side. At this time, the quarter-wave plate 175 retards the phase of the incident P-polarized light so as to be circularly polarized light. The aperture 171 reflects the reflected circularly polarized light back toward the integrator rod 173. The reflected light passes through the quarter-wave plate 175 again and becomes linearly polarized light, for example, S-polarized light, in which the polarization direction is converted, and passes through the polarizer 177 to transmit the polarization beam splitter 180. You will be directed to. Accordingly, the unpolarized light incident on the first polarization recovery integrator 150 is incident on the polarization beam splitter 180 in a state where it is converted into a uniform specific polarized light.

The operation of the second polarization recovery integrator 160 is also substantially the same as the first polarization recovery integrator 150. However, in consideration of the optical arrangement of the first and second polarization recovery integrator 150 (160) with respect to the polarization beam splitter 180, the polarization direction of the light directed to the polarization beam splitter 180 is set differently. For example, when the light illuminated via the first polarization recovery integrator 150 is light of S polarization, the light illuminated through the second polarization recovery integrator 160 is light of P polarization. Of course, the reverse is also possible.

 As such, by providing the first and second polarization recovery integrators 150 and 160 to convert the polarization, the optical loss is achieved while using both the light illuminated by the first and second light source units 110 and 120. It is possible to minimize the lighting efficiency can be increased. In addition, by integrating the structure for uniform light illumination and the structure for polarization conversion integrally, it is possible to make the overall configuration more compact.

The polarization beam splitter 180 transmits light of a specific polarization and reflects light of another polarization, thereby converting a traveling path of incident light. 2, the light incident from the first light source unit 110 is transmitted, and the light incident from the second light source unit 120 is reflected, thereby synthesizing the two lights to proceed in the same path. . The polarizing beam splitter 180 has a cubic structure as shown, or a flat structure (not shown).

In addition, the lighting unit according to the embodiment of the present invention preferably further comprises a relay lens unit 190 composed of one or more lenses for relaying the light synthesized in the polarizing beam splitter 180 to a desired image forming position.

Referring to FIG. 7, the lighting units according to the second exemplary embodiment of the present invention may be disposed at different positions and respectively include first and second light source units 210 and 220 for generating and irradiating light, respectively. First and second polarization recovery integrators 250 and 260 which allow the light illuminated in each of the light source units 210 and 220 to be uniform and have a predetermined polarization, and transmit or reflect incident light according to the polarization direction. And a polarization beam splitter 280 to allow the light emitted from the first and second light source units 210 and 220 to travel in the same path. Compared to the first embodiment, the present embodiment is characterized in that the structures of the first and second light source units 210 and 220 are changed. On the other hand, other components except for this, that is, the first and second polarization recovery integrator 250, 260, polarization beam splitter 280, the condensing lens unit 241, 245 and the relay lens unit 190 Since the optical configuration and arrangement are substantially the same as described above, detailed description thereof will be omitted.

 Each of the first and second light source units 210 and 220 includes a plurality of optical modules 230 for irradiating light of a predetermined wavelength and a synthetic prism 235 for synthesizing the light illuminated by the plurality of optical modules 230. ). Here, since the configuration itself of each of the optical module 230 is substantially the same as the optical module 130 described with reference to FIGS. 3 and 4, a detailed description thereof will be omitted.

Meanwhile, the optical module 230 constituting each of the first and second light source units 210 and 220 may be divided into first to third optical modules 231R, 231G, and 231B according to the wavelength to be irradiated. have. That is, the first optical module 231R includes one or a plurality of optical modules for illuminating light having a red wavelength. Each of the second and third optical modules 231G and 231B includes one or a plurality of optical modules for illuminating light of green and blue wavelengths.

The synthetic prism 235 is disposed between the first to third optical modules 231R, 231G, and 231B, and selectively transmits incident light according to a wavelength, so that the first to third optical modules 231R are disposed. The light of different wavelengths irradiated from 231G and 231B is directed toward the polarization beam splitter 280.

An embodiment of the synthetic prism 235 is a trichroic prism 236 having a structure as shown in FIGS. 7 and 8.

Referring to the drawings, the trichroic prism 236 includes three first to third prisms P1, P2, and P3 bonded to each other. First and second selective for selectively transmitting and reflecting incident light according to a wavelength between each of the first prism and the second prism P1 and P2 and between the second prism P2 and the third prism P3. Reflective films 236a and 236b are formed. For example, the first selective reflective film 236a reflects the first light R, which is a red wavelength emitted from the first optical module 231R, and each of the second and third optical modules 231G and 231B. The second light G, which is the green wavelength, and the third light B, which is the blue wavelength, are irradiated. The second selective reflection film 236b reflects the third light B, and transmits the first and second light R G. FIG.

Accordingly, the first light R incident to the second prism P2 is totally reflected by the critical angle total reflection principle on the surface facing the third prism P3 and is incident on the first selective reflection layer 236a. The first light R is reflected by the first selective reflection film 236a and passes through the second and third prisms P2 and P3. The second light G passes through the first and second selective reflection films 236a and 236b and travels in the same path as the first light R. Lastly, the third light B is totally reflected by the critical angle total reflection principle at the exit surface 236c of the third prism P3 to face the second selective reflection film 236b, and the second selective reflection film 236b. Is reflected by the first and second light beams R and G in the same path.

Meanwhile, another embodiment of the composite prism 235 includes the X-cube prism 238 as shown in FIG. 9. Referring to the drawings, the disclosed X-cube prism 238 may include the first to third incident surfaces 238a, 238b, and 238c to which the first to third lights R, G, and B are respectively incident. An emission surface 238d into which these lights are integrated and output, and first and second selective reflection surfaces 239a and 239b arranged in an X-shape. The first selective reflection surface 239a reflects the first light R incident through the first incident surface 238a and the second incident light through the second and third incident surfaces 238b and 238c. And the third light G (B) is a surface to be transmitted. Meanwhile, the second selective reflection surface 239b reflects the third light B incident through the third incident surface 238c and transmits the remaining first and second lights R and G. . Accordingly, each of the first to third light beams R, G, and B incident through the first to third incident planes 238a, 238b, and 238c may be the first to third selective reflection surfaces 239a. It is synthesized while being selectively transmitted or reflected while passing through 239b, and exits to the exit surface 238d.

As described above, the first to second light source units 210 and 220 are provided with the first to third light modules 230R and the synthetic prism 235 for irradiating light having different wavelengths, thereby providing a light amount of illumination light. Can be increased further.

Referring to FIG. 10, an image projection device according to an exemplary embodiment of the present invention may include an illumination unit 300 for illuminating uniform light and an image forming element 320 for forming an image corresponding to an image signal input from incident uniform light. And a projection lens unit 330 which enlarges and projects the image formed by the image forming element 320 on the screen 340.

The lighting unit 300 includes first and second light source units 301 and 302, first and second polarization recovery integrators 303 and 304, and a polarization beam splitter 305. According to the first and second embodiments of the present invention described with reference to FIGS. 2 to 9 by synthesizing and illuminating the light irradiated from the first and second light source units 301 and 302 disposed at a position It is substantially the same as the configuration of the lighting unit. Therefore, in this embodiment, a detailed description of the lighting unit 300 will be omitted.

Here, the plurality of optical modules constituting the illumination unit 300 is sequentially turned on / off, while sequentially irradiating light of red, green, blue wavelengths. Therefore, in constructing an image projecting device using an image forming element having a one-panel structure, the lighting unit 300 may replace a configuration such as a color wheel (not shown) used for implementing a color image.

The image forming element 320 selectively reflects the incident uniform illumination light in pixel units to form an image. The image forming element 320 is composed of a reflective liquid crystal display element, a DMD (digital micromirror device), or the like. Here, the reflective liquid crystal display device implements an image by using polarization characteristics of incident light, and uses light having a specific polarization. In the present embodiment, by using the light of a specific polarization as a means for synthesizing the light irradiated from the first and second light source units 301 and 302, it is unnecessary to employ a separate polarization conversion element or polarizer.

The DMD includes an independently driven two-dimensional array of micromirror arrays, and forms images by independently setting angles of reflected light for each pixel according to an input image signal.

On the other hand, as described above, when the reflection type is employed as the image forming element 302, the lighting unit 300, the image forming element 320 and the projection lens unit 330 as means for converting the optical path. It is preferable to further include a beam splitter 310 disposed between).

The beam splitter 310 directs the beam incident from the illumination unit 300 toward the image forming element 320, and the beam incident from the image forming element 320 toward the screen 340. The path of the incident beam is converted so as to The beam splitter 310 is a critical angle prism of a structure that transforms the path of the beam by using the critical angle total reflection characteristic, a general beam splitter of a structure that divides the beam by a predetermined light quantity ratio, or a polarization beam of converting the path of the beam according to the polarization direction. It may be configured as a splitter.

The projection lens unit 330 is disposed to face the beam splitter 310, is formed in the image forming element 320, and enlarges an image incident through the beam splitter 310 to enlarge the screen 340. Project toward.

The lighting unit according to the present invention configured as described above has an advantage that the amount of light can be increased by generating light using the first and second light source units, and synthesizing the generated light. In addition, the size of the optical module constituting the first and second light source units can be reduced in size, and the collimated light can be illuminated to increase the light collection efficiency. Further, by integrating the structure for uniform light illumination and the structure for polarization conversion integrally, it is possible to make the whole configuration more compact.

In addition, the image projecting value according to the present invention can be reduced in size by employing the above-described lighting unit. In addition, by forming an image using the light whose light amount is increased and the collimating performance is improved, the image is enlarged at a predetermined ratio and projected onto the screen, thereby improving the quality of the image formed on the screen. In addition, by illuminating the color light using the first to third optical modules for illuminating light of different wavelengths, there is an advantage that a color image can be implemented without a separate color wheel device.

The above embodiments are merely exemplary, and various modifications and equivalent other embodiments are possible from those skilled in the art. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the invention described in the claims below.

Claims (7)

A first light source unit including one or a plurality of optical modules having a collimator having a reflecting surface and a light source positioned in the reflecting surface and irradiating light of a predetermined wavelength; A first polarization recovery integrator for converting the light illuminated from the first light source unit into a uniform first polarized light; A second light source unit disposed at a position different from the first light source unit and including a collimator having a reflective surface and a light source positioned in the reflective surface and irradiating light of a predetermined wavelength; ; A second polarization recovery integrator for converting the light illuminated from the second light source unit into a uniform second polarized light; And a polarization beam splitter for converting the propagation path according to the polarization component of the incident light so that the light of the first and second polarized light incident at different positions travels in the same path. The method of claim 1, Each of the first and second polarization recovery integrators, An integrator rod for causing incident light to be uniform light; A quarter wave plate provided at an exit end of the integrator rod to change a phase of incident light; A polarizer which is provided on one side of the quarter-wave plate and transmits light of a predetermined polarization and reflects light of another polarization; It is provided at the incidence end of the integrator rod, the light incident from each of the first and second light source unit is transmitted, reflecting the light reflected by the polarizer and the incident light through the quarter wave plate back Aperture; lighting unit comprising a. The method according to claim 1 or 2, The optical module of each of the first and second light source units, First to third optical modules for irradiating parallel light of red, green and blue wavelengths, respectively, The first and second light source units, It is disposed between the first to the third optical module, and selectively transmits the incident light according to the wavelength so that the light of different wavelengths irradiated from the first to third optical module toward the polarizing beam splitter direction Prismatic; lighting unit characterized in that it further comprises. The method of claim 3, The synthetic prism, An illumination unit, characterized in that an X-cube prism or a trichroic prism. An illumination unit according to claim 1 or 2; An image forming element for forming an image corresponding to an image signal input from the uniform light emitted from the polarizing beam splitter; And a projection lens unit configured to enlarge and project the image formed by the image forming element on a screen. The method of claim 5, The optical module of each of the first and second light source units, First to third optical modules for irradiating parallel light of red, green and blue wavelengths, respectively, The first and second light source units, It is disposed between the first to the third optical module, and selectively transmits the incident light according to the wavelength so that the light of different wavelengths irradiated from the first to third optical module toward the polarizing beam splitter direction An image projection apparatus further comprising a prism. The method of claim 6, The synthetic prism, An image projection apparatus, characterized in that the X-cube prism or triccroic prism.

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