KR20080024914A - Holding structure of dichroic mirrors and micro projector comprising the same - Google Patents

Abstract

A holding structure of dichroic mirrors and a micro projector having the same are provided to firmly fix the dichroic mirrors to a housing by pressing the dichroic mirrors against receiving parts of the housing with a holder and bent portions of a leaf spring. A holding structure of dichroic mirrors includes a housing(61), a leaf spring(65), and a holder(62). The housing receives a first mirror(27), second and third mirrors(28,29) as the dichroic mirrors, and a reflective mirror(31). The leaf spring covers the bottom of the housing. The holder fixes the second and third mirrors to the housing. The housing has first to fourth receiving parts(61a,61b,61c,61d) to receive the first to third mirrors and the reflective mirror respectively. The holder, screwed to the housing, has a fork part to press lower parts of the second and third mirrors toward the second and third receiving parts so that the second and third mirrors closely adhere to the second and third receiving parts of the housing.

Description

Holding structure of dichroic mirrors and Micro projector comprising the same

1 is a schematic perspective view of a micro projector according to an embodiment of the present invention.

FIG. 2 is a schematic layout view of an optical system viewed from the side of the micro projector shown in FIG. 1.

FIG. 3 is a side view schematically showing a dichroic holding structure of the micro projector shown in FIG. 1.

4 is an exploded perspective view of the dichroic holding structure shown in FIG. 3.

5 is a perspective view showing in detail the housing of the dichroic holding structure shown in FIG.

FIG. 6 is a diagram illustrating a dichroic holding structure excluding a housing in the dichroic holding structure shown in FIG. 4.

FIG. 7 is a diagram showing a path of a light beam passing through the homogenizing means of the micro projector shown in FIG. 1.

8A is a diagram showing a traveling direction and a polarization direction of a light beam incident on a PBS (Polarizing Beam Splitter) and an image display panel.

FIG. 8B is a diagram illustrating a traveling direction and a polarization direction of the light beam incident on FIG. 8A when the pixel is in a black state in the image display panel.

FIG. 8C is a diagram illustrating a traveling direction and a polarization direction of the light beam incident in FIG. 8A when the pixel is in a white state in the image display panel.

Brief description of symbols for the main parts of the drawings

1: Micro projector 2: Menu button

3: exit port 10: projection optical system

20: illumination optical system 21, 22, 23: G light source, R light source, B light source

24, 25, 26: first, second, third focusing lens

27, 28, 29: 1st, 2nd, 3rd mirror 30: (lambda) / 2 filter

31: reflective mirror 32: micro fly eye lens

33: fourth focusing lens 34: collimation lens

35: homogenization means 36: polarizing beam splitter (PBS)

37: lambda / 4 filter 38: polarizer

40 and 140: screen display panel 60: dichroic mirror holding structure

61: housing 61b, 61c: 2nd seating part, 3rd seating part

62: holder 65: leaf spring

65a, 65b: tight contact

The present invention relates to a dichroic mirror holding structure and a micro projector, and more particularly, to reflect light beams from a laser light source of a micro projector that is connected to a portable multimedia device to enlarge and display an image on an external screen. A dichroic mirror holding structure for supporting dichroic mirrors and a micro projector having the same.

Projectors are classified into reflective projectors and projection projectors according to whether the light beams reflect or transmit through the image display panel. In addition, the projector may be classified into a single plate type, two plate type, and three plate type projectors according to the number of image display panels used. In addition, according to the type of light source may be divided into a projector using a lamp light source and a projector using a laser light source.

Projectors using lamp light sources are quite large and difficult to carry. In order to overcome this problem, the development of a projector using a laser light source has been progressed in recent years.

Recently, portable multimedia devices such as digital cameras, digital camcorders, portable media players (PMPs), PSPs, laptop computers and mobile phones have been widely used. As the utilization of such portable multimedia devices increases, the cases of sharing with other people are increasing. In particular, since the portable multimedia device has good mobility, the portability and mobility of the projector should also be good to increase the utilization of the portable multimedia device. Therefore, the necessity for the projector to be manufactured so small that it can be stored in the pocket to increase the portability is increasing.

A micro-projector using a laser light source largely consists of an illumination optical system, an image display panel, and a projection optical system. The illumination optical system serves to incident light beams from the G, R, and B laser light sources onto the image display panel with a uniform light intensity distribution. In particular, in order to efficiently use the space of a micromini projector, dichroic mirrors are required to reflect and refract light beams from a light source. Accordingly, there is a need for a holding structure for easily fixing the dichroic mirrors and firmly fixing the dichroic mirrors so as not to be shaken by impact.

SUMMARY OF THE INVENTION An object of the present invention is to provide a dichroic mirror holding structure for easily and firmly fixing dichroic mirrors for reflecting light beams from laser light sources of a micro projector, and a micro projector having the same. .

The present invention provides a housing having an inclined seating portion on which a dichroic mirror reflecting laser light in a predetermined wavelength range is mounted; And a close means for closely contacting the dichroic mirror to the seating portion.

The seating portion is formed on the side wall surface of the inside of the housing, characterized in that the seating portion is formed to be recessed from the side wall surface of the housing. The housing has an upper surface and a lower surface at least partially open.

The dichroic mirror holding structure further includes a leaf spring coupled to the housing to cover at least a portion of the bottom surface of the housing. In addition, the dichroic mirror holding structure is coupled to the housing, the holder for close contact with one side of the dichroic mirror toward the seat; And an adhesion part protruding from the leaf spring to closely contact one side of the dichroic mirror toward the seating part. The close contact portion is elastically bent to closely contact the dichroic mirror toward the seating portion.

By the above configuration, the dichroic mirror can be fixed to the housing simply, uniformly and firmly. Therefore, even if vibration or impact is applied to the micro-projector, the stability of the illumination optical system can be increased by not shaking.

In addition, according to another aspect of the invention, the light source is arranged in a row so that the exit port for emitting the laser light beam of G, R, B is directed downward, disposed below the respective light sources and the First to third focusing lenses for adjusting width, first to third dichroic mirrors disposed below the first to third focusing lenses and reflecting about 90 degrees so that the light beams are directed backward, the A reflecting mirror that reflects the reflected light beams about 90 degrees upwards, equalizing means for equalizing the light intensity distribution of each of the upwardly directed light beams, and only about a polarization in a predetermined direction of the uniformed light beams toward the rear An illumination optical system including a PBS reflecting 90 degrees and a dichroic mirror holding structure according to any one of claims 1 to 5; An image display panel which modulates G, R, and B light beams from the illumination optical system according to an image signal to form an image, and reflects the modulated light beams by 180 degrees; And a projection optical system having a plurality of lenses arranged in a line such that the light beam forming the image is projected onto an external screen; Disclosed is a micro-projector comprising a.

Hereinafter, embodiments of the present invention shown in the accompanying drawings will be described in detail.

1 is a schematic perspective view of a micro projector according to an embodiment of the present invention. The micro-projector is generally in the shape of a cube, and an exit port through which the light beam is emitted to the external screen is disposed above the front of the projector. And menu buttons for operating the projector are arranged on the top of the projector. Although not shown in the drawing, an input port for receiving an image signal from a portable multimedia device is disposed at the rear of the micro projector.

FIG. 2 is a schematic layout view of an optical system viewed from the side of the micro projector shown in FIG. 1. Referring to FIG. 2, the optical system of the micro-projector is largely composed of an illumination optical system and a projection optical system. The illumination optical system 20 includes a G light source 21, an R light source 22, a B light source 23, first to third focusing lenses 24, 25 and 26, and first to third mirrors 27 and 28. 29, reflecting mirror 31, homogenizing means 32, 33, 34, polarizing beam splitter (PBS) 36, and image display panel 40. The projection optical system 10 includes a series of lenses through which a light beam exiting the image display panel 40 passes.

The light source has a G light source 21, an R light source 22, and a B light source 23 as a laser light source. The G light source 21 according to an embodiment of the present invention is a diode pumping solid state laser (DPSS), and the R light source 22 and the B light source 23 are laser diodes (LDs). LD and DPSS have the advantage of being smaller than other laser light sources. The G light beam coming out of the DPSS has a good linearity compared to the R and B light beams coming from the LD, so the width of the light beam is small. In order to adjust the widths of the G, R, and B light beams to a predetermined size, the first, second, and third focusing lenses 24, 25, and 26 may be configured to adjust the widths of the G, R, and B light sources 21, 22, and 23. It is placed at the bottom.

At this time, the respective light sources are arranged far from the homogenizing means 35 in the order of the G light source 21, the R light source 22, and the B light source 23. That is, the G light source 21 is disposed farthest from the homogenizing means 35. This is to ensure a sufficient travel distance to widen the width of the relatively narrow G light beam to a predetermined size using the first focusing lens 24. In consideration of the widths of the R light beam and the B light beam, since the traveling distance of the R light beam must be larger than the traveling distance of the B light beam, the R light source 22 is disposed farther from the equalizing means than the B light source 23. . However, it is to be understood that the arrangement of the light sources is not necessarily limited thereto, and the arrangement may be changed according to the type of light source to be adopted.

First to third mirrors 27, 28, and 29 are disposed below the first to third focusing lenses 24, 25, and 26, respectively. The first mirror 27 reflects the G light beam counterclockwise by about 90 degrees. That is, the G light beam that has been directed downward is directed backward. The second mirror 28 is a dichroic mirror that reflects the R light beam backward by about 90 degrees and transmits light beams other than the R light beam. The third mirror 29 is a dichroic mirror, which reflects the B light beam backward by about 90 degrees and transmits light beams other than the B light beam. As a result, the G light beams, R light beams, and B light beams from the G light source 21, the R light source 22, and the B light source 23 all travel toward the reflection mirror 31.

Types of the first to third mirrors 27, 28, and 29 may be changed according to the arrangement of the respective light sources. For example, if each light source is disposed away from the homogenizing means 35 in the order of the R light source, the B light source, and the G light source, a first mirror for reflecting the R light beam is disposed below the R light source, A dichroic mirror that reflects only the B light beam and transmits the remaining light beams will be disposed below, and a dichroic mirror that reflects only the G light beam and transmits the remaining light beams will be disposed below the G light source.

Hereinafter, the dichroic mirror holding structure according to the present embodiment will be described with reference to FIGS. 3 to 6. The dichroic mirror holding structure has a housing 61 for receiving a first mirror 27, a second mirror 28, a third mirror 29 and a reflection mirror 31, and covers a lower portion of the housing. The leaf spring 65 is provided, and the contact means which fixes the 2nd mirror 28 and the 3rd mirror 29 to the housing 61 is provided.

As shown in FIG. 4, the housing 61 is open at its upper and lower portions. As shown in FIG. 5, the inner sidewall of the housing 61 accommodates the first mirror 27, the second mirror 28, the third mirror 29, and the reflective mirror 31 from the front side to the rear side. First to fourth seating portions 61a, 61b, 61c, and 61d are formed therein. The first to fourth seating portions 61a, 61b, 61c, and 61d are formed to be recessed from the side wall surface inside the housing 61.

A first mirror 27 is disposed on the first seating portion 61a, a dichroic mirror, which is a second mirror 28, is disposed on the second seating portion 61b, and a first mirror 27 is disposed on the third seating portion 61c. Another dichroic mirror, which is the third mirror 29, is disposed, and the reflective mirror 31 is disposed on the fourth seating portion 61d. The first to third seating portions 61a, 61b, and 61c have inclinations in the same direction, while the fourth seating portion 61d has an inclination in a direction rotated by 90 degrees. That is, each of the G, R, and B light beams is reflected backward by the right angle by the first to third mirrors 27, 28, and 29 disposed on the first to third mounting portions 61a, 61b, and 61c. The G, R, and B light beams all reflect upwardly and travel by the reflection mirror 31 disposed on the fourth mounting portion 61d. The specific slopes of the seating portions are determined according to the paths of the G, R, and B light beams.

Since the first mirror 27 only needs to reflect the G light beam and does not need to be transmitted therethrough, the first mirror 27 can be fixed by attaching one surface to the housing 61. Similarly, the reflection mirror 31 can also be fixed by attaching one surface to the housing 61 since it only needs to reflect all the light beams and not need to transmit them.

On the other hand, since both reflection and transmission occur in the second mirror 28 and the third mirror 29, it is not easy to fix one surface by attaching it to the housing 61. Therefore, in the present invention, the contact means is used to fix the second mirror 28 and the third mirror 29 to the housing 61. As an embodiment of the contact means, it is coupled to the housing 61 and closes the lower side of the second mirror 28 or the third mirror 29 toward the second seat 61b or the third seat 61c. Holder 62 may be used. The holder 62 is fixed to the housing 61 by screws as shown in FIG. 5, and screw tabs 61e and 61f are formed at predetermined positions of the housing 61 for this purpose.

One side of the holder 62 is a fork portion having a fork shape, and the fork portion is bent in accordance with the inclination of the mirror. Accordingly, as the screw 63 penetrating the holder 62 is fastened to the housing 61, the fork portion of the holder 62 may be disposed at the lower portion of the dichroic mirrors 28 and 29 and the second seating portion 61b. The dichroic mirrors 28 and 29 are brought into close contact with the second seating part 61b and the third seating part 61c of the housing by pressing toward the third seating part 61c. 6, the shape of one side of the holder 63 is shown as a fork shape, but the protection scope of the present invention is not limited thereto, and it can be easily changed by those skilled in the art.

On the other hand, the leaf spring 65 is disposed and coupled to the lower surface of the housing 61. The overall shape of the leaf spring 65 corresponds to the shape of the lower portion of the housing 61 to cover the lower surface of the housing 61. As shown in FIG. 6, contact portions 65a and 65b are formed at both sides of the leaf spring 65, and the contact portions 65a and 65b are bent toward the housing 61 from the leaf spring 65. The contact portions 65a and 65b are slightly bent in a direction facing each other to have elasticity. The second mirror 28 and the third mirror 29 are disposed on the seating portions 61b and 61c of the housing, and the second mirror 28 and the third mirror 29 are fixed by the holder 63. Then, as shown in FIG. 4, the leaf spring 65 covers the lower portion of the housing 61, and the leaf spring 65 and the housing 61 are coupled by the fastening means. Then, the close contact portions 65a and 65b of the leaf spring press the two upper portions of the second mirror 28 and the third mirror 29, which are dichroic mirrors, to the seating portions 61b and 61c. That is, as the leaf spring 65 is assembled to the housing 61, the second mirror 28 and the third mirror 29 may be closely adhered to and fixed to each other.

In particular, the dichroic mirrors 28 and 29 are uniformly fixed to the housing 61 by pressing the upper and lower portions of the dichroic mirrors 28 and 29 toward the seating portions 61b and 61c. In addition, the close contact portions 65a and 65b of the leaf spring are elastically bent to move the second mirror 28 and the third mirror 29 toward the second seating portion 61b and the third seating portion 61c of the housing. Because it adheres tightly, it is firmly fixed As a result, even if a shock or vibration occurs in the micro-projector, the stability of the illumination optical system 20 can be guaranteed.

The G light source 21 has a substantially circular shape and is polarized light which vibrates in the vertical direction in a cross section perpendicular to the advancing direction. The R light source 22 has an elliptical shape and is polarized light that vibrates in the vertical direction in a cross section perpendicular to the advancing direction. The B light source 23 has an elliptical shape and is polarized light that vibrates in left and right directions in a cross section perpendicular to the advancing direction.

However, as shown in FIG. 7, in order to reduce the light loss in the PBS 36, the polarization of the light beam incident on the micro fly's eye lens 32 should be the polarization oscillating in the vertical direction in a cross section perpendicular to the traveling direction. do. Therefore, it is necessary to convert the polarization of the B light beam in the left and right directions to the polarization in the vertical direction. For this purpose, a λ / 2 filter (half wave plate) 30 is disposed below the B light source 23. Thereby, the polarization of the G light beam, the R light beam, and the B light beam is all the polarization in the vertical direction in the cross section perpendicular to the traveling direction, so that the light loss in the PBS 36 can be reduced.

The G light source 21, the R light source 22, and the B light source 23 operate in conjunction with an output signal of a controller to be described later in accordance with an image signal input through an input channel from the outside. That is, the G light beam, the R light beam, and the B light beam are emitted from the G light source 21, the R light source 22, and the B light source 23 by the output signal of the controller.

The reflection mirror 31 counterclockwise the G light beam, the R light beam, and the B light beam emitted from each light source and reflected on each of the first to third mirrors 27, 28, and 29 by about 90 degrees. Refraction In other words, each light beam directed backward is directed upward. At this time, the reflection mirror 31 is a mirror that reflects all of the G light beam, the R light beam, and the B light beam. Each light beam reflected by the reflection mirror 31 is incident on the equalizing means 35.

FIG. 7 is a view showing the equalizing means 35 and the path of the light beam passing through the equalizing means 35 according to an embodiment of the present invention. As an embodiment of the homogenizing means 35 a micro fly-eye lens 32, a fourth focusing lens 33 and a collimation lens 34 are used. The micro fly's eye lens 32 is disposed above the reflection mirror 31, the fourth focusing lens 33 is disposed above the micro fly's eye lens 32, and the collimation lens 34 is the fourth focusing lens. It is arrange | positioned above 33.

Each light beam must be accurately incident on the entire effective area of the micro fly's eye lens 32. This can be achieved by adjusting the focusing lenses 24, 25, 26 disposed below each light source.

The light intensity distribution of the light beam incident on the micro fly's eye lens 32 is large at the center and small at the periphery as shown in FIG. 7. The incident light beam is split by the micro fly's eye lens 32. Each divided light beam is incident across the collimation lens 34 while passing through the fourth focusing lens 33. That is, since the light beams split at the center and both peripheral parts are all incident through the collimation lens 34 by the fourth focusing lens 33, the light intensity distribution of the light beam passing through the collimation lens 34 as a whole. Become uniform. Therefore, the light intensity distribution of the light beam incident on the PBS 36 becomes uniform.

In the present invention, the homogenizing means 35 is provided with a micro fly's eye lens 32, but may be provided with a diffraction optical element (DOE).

The image display panel 40 serves to form an image by modulating a light beam according to an image signal input from the outside. As an example of the image display panel 40, a digital micromirror display (DMD) panel, an LCD panel, a liquid crystal on silicon (LCoS) panel, a diffractive optical display element, or the like can be used. The image display panel 40 according to an embodiment of the present invention is an LCoS panel.

Although not shown in the figure, an LCoS panel includes indium tin oxide glass, liquid crystal, aluminum pixels, and a CMOS substrate. Light incident through the ITO glass may be reflected by rotating the polarization direction by 90 degrees according to the molecular arrangement of the liquid crystal of each pixel, or may be reflected by keeping the polarization direction. The molecular arrangement of the liquid crystal is controlled according to the voltage applied to the electrodes of each pixel through the CMOS substrate. That is, the controller applies a voltage to a specific pixel in response to an image signal input from the outside, and the polarization direction of the light beam is controlled by changing the molecular arrangement of the liquid crystal corresponding to the specific pixel according to whether the voltage is applied.

Unlike the transmissive LCD, the LCoS panel 40 reflects the light beam incident through the liquid crystal and exits again. In other words, the aperture ratio is high because it does not transmit through CMOS. Therefore, the LCoS panel 40 has a higher light transmittance and a higher luminance than a transmissive LCD.

8A to 8C, the operation principle of advancing each light beam from the PBS 36 and the image display panel 40 to the projection optical system 10 will be described. As shown in Fig. 8A, each of the light beams having uniform light intensity and polarized light oscillating in the vertical direction in the cross section perpendicular to the advancing direction is incident on the PBS 36. The PBS 36 has only about 90 degrees of polarized light oscillating in a predetermined direction among the light beams emitted through the homogenizing means 35 and in the vertical direction in the cross section perpendicular to the traveling direction of the light beam in the embodiment of the present invention. Reflect in the direction. That is, only the polarization oscillating in the vertical direction is directed backward, and the remaining polarization is transmitted. The polarized light vibrating in the reflected vertical direction is incident on the image display panel 40.

As shown in FIG. 8B, the light beam incident on the black state pixel among the pixels of the image display panel 40 is reflected on the image display panel 40 while maintaining the same polarization direction. . As a result, since the light is reflected back to the PBS 36, the light beam does not proceed toward the projection optical system 10. Therefore, G, R, and B light are not formed in the external screen corresponding to the pixel in the dark state.

As shown in FIG. 8C, the light beam incident on the white state pixel among the pixels of the image display panel 40 is reflected on the image display panel 40 with the polarization direction rotated 90 degrees. . As a result, since the reflected light beam is polarized light oscillating in the left and right direction in the cross section perpendicular to the traveling direction, the light beam passes through the PBS 36 and travels toward the projection optical system 10. Therefore, G, R, and B light are formed on the external screen corresponding to the pixel in the bright state.

In this case, the pixel to which the voltage is applied may be set to a bright state. Alternatively, the pixel to which the voltage is applied may be set to a dark state.

On the other hand, the light beam that has passed through the homogenizing means 35 should be incident perpendicularly to the incident surface 36a of the PBS 36 in principle. However, in reality, a skew ray that is not perpendicular to the incident surface 36a is generated, and the skew ray is reflected from the reflective surface 36b of the PBS 36 with the polarization direction slightly rotated. To correct this, a λ / 4 filter 37 may be additionally disposed in the light beam path between the PBS 36 and the image display panel 40.

In addition, a polarizer 38 may be additionally disposed between the PBS 36 and the projection optical system 10. The polarizer 38 passes only the polarization oscillating in the left and right directions in the cross section perpendicular to the traveling direction of the light beam. That is, it filters out polarization other than desired polarization. Thus, the λ / 4 filter 37 and / or polarizer 38 improves the contrast of the image.

Up to now, although the reflective image display panel 40 has been described as the image display panel 40, a transmissive image display panel, for example, a transmissive LCD panel, may be used as another embodiment of the present invention.

The micro-projector 1 according to an embodiment of the present invention further includes a control unit (not shown) and a heat dissipation unit 50 in addition to the illumination optical system 20 and the projection optical system 10. The controller controls the operations of the G light source 21, the R light source 22, and the B light source 23 according to the image signal input from the outside, and controls the operation of the image display panel 40. The heat dissipation unit 50 serves to discharge heat generated by the G light source 21, the R light source 22, and the B light source 23. To this end, the heat dissipation unit is configured to surround the G light source 21, the R light source 22, and the B light source 23, and heat dissipation fins are provided on the surface of the heat dissipation unit to increase the heat dissipation area.

Next, a process of magnifying and projecting an image on an external screen by the micro-projector 1 according to an exemplary embodiment of the present invention will be described.

When the micro projector 1 is connected to an external multimedia device through its input port, the image signal from the multimedia device is input to the control unit of the micro projector. The control unit controls the image display panel 40 in accordance with the input image signal. Then, the arrangement of the liquid crystals 42 corresponding to the specific pixels to be operated to form the image is changed. On the other hand, the G light source 21, the R light source 22, and the B light source 23 are operated in conjunction with the image display panel 40 by the control unit, and the G light beam, R from each light source 21, 22, 23 is operated. The light beam and the B light beam are sequentially emitted.

Each light beam passes through the first to third focusing lenses 24, 25, 26, respectively, and is reflected by the first to third mirrors 27, 28, 29, respectively, and is incident on the reflection mirror 31. Each light beam reflected by the reflection mirror 31 has a uniform light intensity by the equalizing means 35. Each light beam having a uniform light intensity is incident on the reflective image display panel 40 such as LCoS by reflecting only polarized light in a predetermined direction in the PBS 36.

The light beams incident on the specific cells according to the image signal in the LCoS 40 are reflected in the opposite directions with the polarization direction rotated by 90 degrees, passing through the PBS 36, and incident on the projection optical system 10. Each incident light beam is magnified while passing through the projection optical system 10, thereby projecting the magnified image onto the external screen. At this time, the G light beam, the R light beam, and the B light beam are sequentially projected on the external screen in a very short time. That is, G images, R images, and B images are sequentially projected on the external screen at extremely short time intervals. As a result, the projected R image, G image, and B image are superimposed to form one image. In addition, a moving image is formed by successively projecting each image thus formed.

The micro-projector of the present invention adopts the dichroic mirror holding structure described above, and the dichroic mirror holding structure uses the dichroic mirror by pressing the dichroic mirror toward the seating portion of the housing using the bent contact portion of the holder and the leaf spring. The blade mirror can be fixed to the housing simply, uniformly and firmly. Therefore, even if vibration or impact is applied to the micro-projector, the stability of the illumination optical system can be increased by not shaking.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (9)

A housing having an inclined seating portion on which a dichroic mirror reflecting laser light in a predetermined wavelength range is mounted; And Dichroic mirror holding structure comprising a; close contact means for close contact with the dichroic mirror toward the seating portion. According to claim 1, The seating portion is formed on the side wall surface of the inside of the housing, the seating portion is a dichroic mirror holding structure formed to be recessed from the side wall surface of the housing. According to claim 1, And the contact means presses at least three portions of the dichroic mirror so that the dichroic mirror is in uniform contact with the seating portion. According to claim 1, The housing has an upper surface and a lower surface at least partially open, And a leaf spring coupled to the housing to cover at least a portion of the lower surface of the housing. The method of claim 4, wherein A holder coupled to the housing and closely contacting one side of the dichroic mirror toward the seating part; And And a close contact portion protruding from the leaf spring and closely contacting one side of the dichroic mirror toward the seating portion. The method of claim 5, And the close contact portion is elastically bent to closely contact the dichroic mirror toward the seating portion. Light sources arranged in a row such that the exit holes emitting the G, R, and B laser beams face downward, and first to third focusing lenses disposed below the respective light sources and adjusting the widths of the respective light beams. For example, first to third mirrors disposed below the first to third focusing lenses and reflecting about 90 degrees so that the light beams are directed backward, and reflecting about 90 degrees so that the reflected light beams are directed upward. A reflection mirror, homogenization means for equalizing the light intensity distribution of each of the upwardly directed light beams, a PBS for reflecting about 90 degrees so that only polarization in a predetermined direction of the uniformed light beams is directed backwards, and the first to fifth points An illumination optical system comprising the dichroic mirror holding structure of claim 1; An image display panel modulating the G, R, and B light beams from the illumination optical system according to an image signal to form an image, and reflecting the modulated light beams by 180 degrees; And And a projection optical system including a plurality of lenses arranged in a line such that the light beam forming the image is projected onto an external screen. The method of claim 7, wherein And the image display panel is a liquid crystal on silicon (LCoS). The method of claim 7, wherein the equalizing means, A micro fly-eye lens disposed on an optical beam path between the reflective mirror and the PBS, the micro fly-eye lens splitting the respective G, R, and B light beams reflected by the reflective mirror; And A fourth focusing lens and a collimation lens disposed on a light beam path between the micro fly's eye lens and the PBS and condensing the split light beam to equalize the light intensity distribution of the light beam incident on the PBS; Including micro projector.

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