JP5743605B2 - Image projection device - Google Patents

Description

  The present invention relates to an image projection apparatus such as a liquid crystal projector, and more particularly to a structure for performing maintenance of the image projection apparatus.

  In an image projection apparatus, for example, some optical elements whose characteristics change (deteriorate) by receiving strong light from a light source lamp are used, such as an optical element using a film formed of an organic material. . Such optical elements need to be replaced if their characteristics change. For this reason, it is required for the configuration of the image projection apparatus to be able to exchange the optical elements as easily as possible.

  Further, in an image projection apparatus, a light modulation element such as a liquid crystal panel and an optical element in the vicinity thereof are particularly likely to become high temperature because light from a light source lamp is condensed there. For this reason, the image projection apparatus is provided with a duct that guides air from the fan to the light modulation element or an optical element in the vicinity thereof and cools them. An optical element in the vicinity of the light modulation element is a color separation that decomposes light from a light source lamp into a plurality of color lights, leads them to a plurality of light modulation elements, and combines a plurality of color lights modulated by the plurality of light modulation elements An optical element included in the synthesis optical system.

  Since the duct occupies a relatively large volume inside the housing of the image projection apparatus, it is often necessary to remove the duct when replacing the optical element.

  In Patent Document 1, when a duct arranged on the lower side (bottom side) of the light modulation element and the optical element in the vicinity of the light modulation element in the casing is removed from the opening on the bottom side of the casing, the light modulation element and its An image projection apparatus is disclosed in which adjacent optical elements are exposed facing the opening. In this image projection apparatus, it is easy to access the exposed light modulation element and the optical element in the vicinity thereof, and dust attached to these elements can be easily removed (cleaned). It is also considered that the exposed optical element can be easily replaced.

JP 2008-14962 A

  However, in the image projection apparatus disclosed in Patent Document 1, the duct, the light modulation element, and the optical element in the vicinity thereof can be accessed only from the bottom surface side of the apparatus. There is a problem that it has to be reversed upside down and is troublesome. When the duct is removed with the bottom of the apparatus turned upside down and the opening on the bottom side opened upward, the light modulation element and the optical element in the vicinity thereof are exposed facing the opening. For this reason, after these cleaning and replacement, dust that has entered the inside of the housing from the outside through the opening will adhere to the light modulation element and the optical element.

  Further, Patent Document 1 discloses an access method for an optical element included in a light modulation element and a color separation / synthesis optical system, but constitutes an illumination optical system that guides light from a light source lamp to the color separation / synthesis optical system. No access method is disclosed for the optical element. However, it is desirable that the optical elements constituting the illumination optical system can be easily accessed.

  The present invention provides an image projection apparatus having a configuration in which dust entering from the outside hardly adheres to an optical element while facilitating access to an optical element that requires replacement.

An image projection apparatus according to an aspect of the present invention decomposes light from a light source into a plurality of color lights, guides them to a plurality of light modulation elements, and synthesizes and projects a plurality of color lights modulated by the plurality of light modulation elements. A color separation / synthesis optical system that leads to the optical system; an optical box that houses a plurality of light modulation elements and the color separation / synthesis optical system; and a duct connection port of the optical box; It has a duct for guiding cooling air, and an optical box and a housing for accommodating the duct. The color separation / synthesis optical system includes a first optical element. Inside the housing, the optical box and the duct are arranged adjacent to each other physicians across the duct joint which opens in a first direction along the upper surface of the housing. The upper surface of the housing has a cover portion that covers at least the upper surface of the optical box, a duct holding portion that removably holds a duct disposed inside the housing, and a second direction different from the first direction. An opening is provided, and an upper surface opening that allows the duct removed from the duct holding portion to be taken out from the inside of the housing. The first optical element is attached to and detached from the color separation / synthesis optical system inside the optical box through the duct connection port and the upper surface opening in a state where the duct is taken out from the inside of the housing. To do.

  According to the present invention, when the duct removed from the duct holding portion provided on the top surface of the housing is taken out from the inside of the housing through the top surface opening, the top surface opening and the duct connection port not directly facing the top surface opening are provided. Through the first optical element. In addition, the upper surface opening has only a size necessary for enabling removal (and insertion) of the duct, and at least covers the upper surface of the optical box. Therefore, the first optical element can be easily attached and detached (replaced), and dust that has entered from the outside of the housing through the upper surface opening enters the optical box and enters the light modulation element and the optical element in the optical box. A configuration that is difficult to adhere can be realized.

1 is a top view of a projector that is an embodiment of the present invention. FIG. FIG. 2 is a diagram illustrating an optical configuration of a projector according to an embodiment. FIG. 3 is a top view illustrating a cooling configuration of the projector according to the embodiment. Sectional drawing which shows the structure of the periphery of the wavelength-selective phase plate in the projector of an Example (cross-sectional view in the AA line in FIG. 1). The figure which shows the state by which the duct was removed in the structure shown in FIG. Sectional drawing which shows the structure of the periphery of the polarization conversion element in the projector of an Example (sectional drawing in the BB line in FIG. 1). The figure which shows the state from which the duct was removed in the structure shown in FIG. FIG. 2 is a perspective view illustrating an appearance of the projector according to the embodiment. The perspective view which shows the state which removed the protective cover from the projector shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows the overall configuration of a liquid crystal projector (image projection apparatus) that is Embodiment 1 of the present invention. Reference numeral 1 denotes a light source lamp (hereinafter simply referred to as a lamp), and a high-pressure mercury discharge lamp is used in this embodiment. However, a discharge lamp other than the high-pressure mercury discharge lamp may be used as the light source lamp 1.

  2 is a lamp holder for holding the lamp 1, and 3 is an explosion-proof convex lens. A lamp unit 4 includes a lamp 1, a lamp holder 2, and an explosion-proof convex lens 3.

  α denotes an illumination optical system that converts the light beam from the lamp 1 into a parallel light beam having a uniform brightness distribution. β is the light (light from the lamp 1) from the illumination optical system α, which is decomposed into R (red) light, G (green) light, and B (blue) light, which are a plurality of color lights, into three liquid crystal panels described later. A color separation / synthesis optical system that combines the R light, the G light, and the B light that is guided and further modulated by the three liquid crystal panels.

  Reference numeral 5 denotes a projection lens barrel that houses a projection lens (projection optical system) that projects the combined light (image) from the color separation / synthesis optical system β onto a screen (projected surface) (not shown).

  Reference numeral 6 denotes an optical box that houses the lamp 1, the illumination optical system α, and the color separation / synthesis optical system β and to which the projection lens barrel 5 is fixed. The opening on the upper surface of the optical box 6 is covered with an optical box lid 7 shown in FIG. 4 and the like in a state where the illumination optical system α and the color separation / synthesis optical system β are accommodated in the optical box 6. In the following description, the optical box 6 whose upper surface opening is closed by the optical box lid 7 is referred to as an optical box 6.

  A power supply unit 8 has an AC inlet (not shown). Reference numeral 9 denotes a ballast that generates a lamp power source for lighting the lamp 1 using the power supplied from the power supply unit 8.

  Reference numerals 10 and 11 denote a first optical system cooling fan and a second optical system cooling fan, respectively, and optical elements in the color separation / synthesis optical system β by outside air (air) sucked from an air inlet 18a provided in the exterior cabinet 18. It is provided for cooling a liquid crystal panel described later.

  Reference numeral 12 denotes an optical system intake duct that holds the first and second optical system cooling fans 10 and 11 and guides outside air from the intake port 18a to the first and second optical system cooling fans 10 and 11.

An optical unit 13 is held by a cabinet lid 19 shown in FIG. 9 and guides the cooling air discharged from the first and second optical system cooling fans 10 and 11 to the color separation / synthesis optical system β inside the optical box 6. System cooling duct. The optical system cooling duct 13 is connected to a duct connection port 6 a formed in the optical box 6. That is, the optical box 6 and the optical system cooling duct 13 are disposed adjacent to each other in the horizontal direction (first direction) along the cabinet lid 19 that constitutes the upper surface of the housing with the duct connection port 6a interposed therebetween. .

  Reference numeral 14 denotes an exhaust fan. The air discharged from the exhaust fan 14 cools the power supply unit 8 and the ballast 9, cools the lamp 1, and is exhausted to the outside from an exhaust port 18 b provided in the exterior cabinet 18.

  An exhaust fan holder 15 holds the exhaust fan 14. Reference numeral 16 denotes a lamp cooling fan. The drive / control board unit 21 to be described later is cooled by the air flow sucked in by the lamp cooling fan 16, and the polarization conversion element 45 and the lamp 1 in the illumination optical system α are cooled by the air discharged from the lamp cooling fan 16. To do.

  A lamp cooling duct 17 guides the cooling air discharged from the lamp cooling fan 16 to the polarization conversion element 45 and the lamp 1 included in the illumination optical system α.

  The exterior cabinet (lower casing) 18 has the above-described intake port 18a and exhaust port 18b, and constitutes the casing of the projector of the present embodiment together with the above-described cabinet lid (upper casing) 19. In the region corresponding to the upper surface of the optical system cooling duct 13 which is a part of the cabinet lid 19 constituting the upper surface of the housing as described above, an opening (hereinafter referred to as the shape of the upper surface of the optical system cooling cabinet 13). An upper surface opening).

  Note that the upper surface in this embodiment means the upper surface (surface opposite to the bottom surface of the projector provided with legs not shown) when the projector is installed on a desk or table. . When the projector is used with the ceiling suspended, the upper surface in this embodiment is actually the lower surface.

  Reference numeral 20 denotes a dust filter that covers the intake port 18a and removes dust from the air sucked from the intake port 18a.

  The drive / control board unit 21 is an electric circuit board on which an electric circuit for operating the projector is mounted. The drive / control board unit 21 is an interface for capturing signals such as image signals and control signals, driving of the liquid crystal panel using the power from the power supply unit 8, lighting of the lamp 1, and driving of the fans 10, 11, 14, 16 These controls are performed in accordance with the above signals. The drive / control board unit 21 has a space other than the space between the cabinet lid 19 and the optical system cooling duct 13 in the housing (in this embodiment, the optical system is cooled with respect to the projection lens barrel 5 in the horizontal direction). It is arranged in a space on the opposite side to the duct 13). And it is being fixed to the exterior cabinet 18 via the holder not shown.

  Next, the optical configuration of the projector of this embodiment will be described with reference to FIG. In FIG. 2, a horizontal section is shown on the left side, and a vertical section is shown on the right side. The same components as those shown in FIG. 1 are denoted by the same reference numerals as those in FIG.

  In the figure, reference numeral 1 denotes the above-described lamp, which condenses and emits light (white light) from the discharge arc tube 41 in a predetermined direction by a reflector 42. Reference numeral 3 denotes the explosion-proof convex lens described above.

  43 is a first fly-eye lens, and 44 is a second fly-eye lens. The light from the light source lamp 1 is divided into a plurality of light beams by the first and second fly-eye lenses 43 and 44.

  A polarization conversion element (second optical element) 45 converts non-polarized light from the lamp 1 into linearly polarized light having a predetermined polarization direction. Reference numeral 46 denotes a reflection mirror for bending the optical axis from the lamp 1.

  47a is a first condenser lens, and 47b is a second condenser lens. These first and second condenser lenses 47a and 47b have a light condensing function to superimpose a plurality of light beams formed by the first and second fly-eye lenses 43 and 44 on a liquid crystal panel described later.

  The first fly-eye lens 43, the second fly-eye lens 44, the polarization conversion element 45, the reflection mirror 46, the first condenser lens 47a, and the second condenser lens 47b constitute an illumination optical system α.

  Reference numeral 48 denotes a dichroic mirror that reflects B light and R light and transmits G light. A trimming filter 49 returns orange light to the lamp 1 in order to increase the color purity of the R light.

  Reference numeral 50 denotes a reflection type polarization selection element that transmits only P-polarized light. Reference numeral 51 denotes a color selective phase difference plate (first optical element) that converts the polarization direction of the R light by 90 degrees and does not convert the polarization direction of the B light.

  Reference numerals 52 and 53 denote a first polarization beam splitter and a second polarization beam splitter, respectively, which transmit P-polarized light and reflect S-polarized light on a polarization separation surface formed of a multilayer film.

  57R, 57G, and 57B are respectively a quarter wavelength plate for R, a quarter wavelength plate for G, and a quarter wavelength plate for B.

  58R, 58G, and 58B are a red reflective liquid crystal panel, a green reflective liquid crystal panel, and a blue reflective liquid crystal panel as light modulation elements that reflect incident light and modulate the image, respectively. 55 is a polarizing plate for B, and 56 is a polarizing plate for G.

  A dichroic prism 54 transmits R light and B light and reflects G light.

  The above dichroic mirror 48 to dichroic prism 54 constitute a color separation / synthesis optical system β.

  Next, a cooling structure in the projector of this embodiment will be described with reference to FIG. As described above, the projector according to the present embodiment includes the four fans 10, 11, 14, and 16, and uses these four fans 10, 11, 14, and 16 to provide two cooling air paths (first and second). A second cooling air passage) is formed.

  First, the first cooling air path indicated by the solid line arrow in FIG. 3 will be described. As the first and second optical system cooling fans 10 and 11 and the lamp cooling fan 16 rotate, air outside the apparatus (housing) flows from the air inlet 18a through the dust filter 20 into the housing.

  The air that has flowed into the housing through the dust filter 20 passes through the optical system intake duct 12 and is sucked by the first and second optical system cooling fans 10 and B11. The air discharged from each of the first and second optical system cooling fans 10 and 11 merges in the optical system cooling duct 13, passes through the duct connection port 6 a formed in the optical box 6, and enters the optical box 6. Inflow. Then, the optical elements and the reflective liquid crystal panels 58R, 58G, and 58B included in the color separation / synthesis optical system β are cooled. The air that has cooled the optical elements of the color separation / synthesis optical system β and the reflective liquid crystal panels 58R, 58G, and 58B flows to the drive / control board unit 21.

  The lamp cooling fan 16 sucks the air discharged from the first and second optical system cooling fans 10 and 11 and flowing into the drive / control board unit 21. Air convection generated by the intake of the lamp cooling fan 16 cools the drive / control board unit 21. The air discharged from the lamp cooling fan 16 flows through the lamp cooling duct 17 toward the polarization conversion element 45 and the lamp 1 included in the illumination optical system α.

  The air flowing toward the polarization conversion element 45 cools the polarization conversion element 45, passes through an air guide portion provided in the optical system cooling duct 13, and is formed around the lamp 1 and by the exhaust fan 14. 2 Flow into the cooling air passage.

  The air flowing toward the lamp 1 passes through an opening (not shown) provided in the lamp holder 2 and flows into a space surrounded by the lamp 1, the lamp holder 2 and the explosion-proof convex lens 3. Cooling. The air that has cooled the discharge arc tube 41 flows out of the lamp unit 4 through an opening (not shown) provided in the lamp holder 2. The air flowing out from the lamp unit 4 flows into the second cooling air passage.

  Next, the second cooling air passage indicated by a dotted arrow in FIG. 3 will be described. As the exhaust fan 14 rotates, air outside the housing flows from the air inlet 18a through the dust filter 20 into the housing. The air that has flowed into the housing through the dust filter 20 is sucked into the exhaust fan 14 after cooling the power supply unit 8 and the ballast 9. The air discharged from the exhaust fan 14 cools the entire lamp unit 4, cools the lamp 1 and the polarization conversion element 45, and is discharged from the exhaust port 18 b to the outside of the housing together with the air flowing from the first cooling air passage. Is done.

  The procedure for replacing the wavelength selective phase plate 51 in the projector of the present embodiment configured as described above will be described with reference to FIGS. FIG. 4 shows a cross section of the peripheral portion of the wavelength selective phase plate 51 before replacement of the wavelength selective phase plate 51 (cross section taken along the line AA in FIG. 1). 5 shows the same cross section when the wavelength selective phase plate 51 is replaced.

  In FIG. 4, the optical system cooling duct 13 is held (fixed) by a duct holding portion 19 a provided in the cabinet lid 19. The wavelength selective phase plate 51 is held by the optical element holder 22 together with the trimming filter 49 and the polarization selection element 50. The optical element holder 22 is provided with an optical element holding plate 23, and the positions of the trimming filter 49, the polarization selection element 50, and the wavelength selective phase plate 51 are determined by the optical element holding plate 23.

  The optical element holder 22 is provided with a grip portion 22a. The optical element holder 22 is held at a predetermined position (a position included in the color separation / synthesis optical system β) in the optical box 6 by engaging a hooking claw (not shown) provided in the optical box 6. .

When exchanging the wavelength selective phase plate 51, as shown in FIG. 5, the optical system cooling duct 13 held by the duct holding portion 19a of the cabinet lid 19 is moved vertically to the cabinet lid 19 (second direction). It is removed in the direction of the solid line arrow (upward) through the opening 19b formed to open. Hereinafter, the opening 19b is referred to as an upper surface opening 19b. By removing the optical system cooling duct 13, a space S is created at the place where the optical system cooling duct 13 is disposed inside the housing, and the duct connection of the optical box 6 to which the optical system cooling duct 13 is connected is made. The mouth 6a is connected to the space S.

Next, the optical element holder 22 is slid (moved) in the direction of the dotted arrow (first direction) toward the space S through the duct connection port 6a, removed from the color separation / synthesis optical system β, and from within the optical box 6 Take out. At this time, the operator can easily take out the optical element holder 22 by grasping the grip portion 22 a of the optical element holder 22.

Next, the optical element holder 22 taken out from the optical box 6 passes through the upper surface opening 19b from which the optical system cooling duct 13 is taken out from the inside of the housing, and is in the same direction as the direction in which the optical system cooling duct 13 is taken out (dotted line arrow). In the direction indicated by : 2nd direction ).

  The wavelength selective phase plate 51 can be exchanged by taking out the wavelength selective phase plate 51 held by the optical element holder 22 to the outside through the upper surface opening 19b of the housing. At this time, the duct connection port 6a of the optical box 6 opens in the horizontal direction and does not face the upper surface opening 19b. In other words, the duct connection port 6a is opened in such a direction that dust that has entered the inside of the housing through the upper surface opening 19b due to gravity is less likely to enter the optical box 6 through the duct connection port 6a. Therefore, a configuration is realized in which dust outside the housing is less likely to adhere to the optical elements in the optical box 6 and the reflective liquid crystal panels 58R, 58G, and 58B during the replacement of the wavelength selective phase plate 51.

  Further, as shown in FIG. 9, the upper surface opening 19 b formed in the cabinet lid 19 has a shape that matches the shape of the optical system cooling duct 13 in order to allow the optical system cooling duct 13 to be taken out. Yes. And the cover part 19c which is the other part has covered the upper surface of the optical box 6 (parts other than the optical box 6 and other optical system cooling ducts 13) in a housing | casing at least. Thereby, compared with the case where the whole upper surface of a housing | casing is open | released, it becomes difficult for dust to penetrate | invade from the exterior of a housing | casing. Accordingly, it is possible to realize a configuration in which dust is less likely to adhere to the optical elements in the optical box 6 and the reflective liquid crystal panels 58R, 58G, and 58B.

  Next, an exchange procedure of the polarization conversion element 45 will be described with reference to FIGS. FIG. 6 shows a cross section of the peripheral portion of the polarization conversion element 45 before replacement of the polarization conversion element 45 (cross section taken along the line BB in FIG. 1), and FIG. The same cross section at the time of replacement | exchange of the conversion element 45 is shown.

  In FIG. 6, the optical system cooling duct 13 is held by the duct holding portion 19 a of the housing cabinet lid 19 as described above. Further, the polarization conversion element 45 is held by a spring member (not shown) held in the optical box 6 except for its upper end. The upper end portion of the polarization conversion element 45 is pressed against the optical box 6 by a pressing portion 13 a provided in the optical system cooling duct 13, so that the polarization conversion element 45 does not rattle and the inside of the optical box 6 (illumination optics). It is held at a predetermined position in the system α).

  As with the replacement of the wavelength selective phase difference plate 51, the polarization conversion element 45 is also replaced by the optical system cooling duct 13 held by the duct holding portion 19a of the housing cabinet lid 19 as shown in FIG. It is possible to remove it from the line and take it out in the direction of the solid arrow (upward). When the optical system cooling duct 13 is removed, the pressing of the upper end portion of the polarization conversion element 45 by the pressing portion 13a is released, and a space is formed above it. For this reason, the polarization conversion element 45 can be removed with respect to the optical box 6 in the direction of the dashed arrow.

  By removing the optical system cooling duct 13 in this manner, not only the wavelength-selective phase difference plate 51 but also the polarization conversion element 45 can be exchanged. Therefore, these exchanges can be performed easily and in a short time. it can.

  In FIG. 8, an exterior protective cover 24 is attached on a cabinet lid 19 which is the upper surface of the housing by a mounting structure such as a screw or engagement (not shown), and the optical system cooling duct 13 is installed in a normal projector use state. The state which made it impossible to visually recognize is shown. When exchanging the wavelength-selective phase difference plate 51 or the polarization conversion element 45, the exterior protection cover 24 is removed to expose the cabinet lid 19 and the optical system cooling duct 13, and then the optical system cooling duct 13 is removed. .

  Note that the exterior protective cover 24 can be dispensed with by making the upper surfaces of the cabinet lid 19 and the optical system cooling duct 13 finish surfaces suitable for exterior.

  As described above, in this embodiment, the optical system cooling duct 13 is removed from the cabinet lid 19 and taken out from the upper surface opening 19b to the outside of the housing, thereby forming a space S inside the housing. As a result, the duct connection port 6a of the optical box 6 that has been blocked by the optical system cooling duct 13 is opened. Therefore, the wavelength-selective phase difference plate 51 can be attached to and detached from (replaced with) the color separation / synthesis optical system β inside the optical box 6 through the upper surface opening 19b, the space S, and the duct connection port 6a.

  Moreover, the duct connection port 6a does not directly face the upper surface opening 19b (opens in a direction orthogonal to each other), and the upper surface of the housing other than the upper surface opening 19b for taking out the optical system cooling duct 13 is a cabinet. The cover 19 is covered with a cover portion 19c. For this reason, during the replacement of the wavelength selective phase difference plate 51, dust outside the casing enters the casing through the upper surface opening 19b, and further enters the optical box 6 through the duct connection port 6a. The possibility can be reduced. Therefore, it is possible to make it difficult for dust to adhere to the optical elements and the liquid crystal panel in the optical box 6 during the replacement.

  Further, in this embodiment, the polarization conversion element 45 can be replaced by removing the optical system cooling duct 13. Therefore, the structure for exchanging the polarization conversion element 45 can be replaced with the wavelength selective phase plate 51. There is no need to provide a separate structure. For this reason, while being able to simplify the structure inside a housing | casing, the workability | operativity at the time of exchanging both elements simultaneously can be improved.

  Also, since the optical system cooling duct 13 is provided with a holding structure for the polarization conversion element 45 in the normal state, the polarization conversion element 45 can be attached and detached simply by removing the optical system cooling duct 13.

  In addition, since the drive / control board unit 21 is arranged in a space other than the space between the cabinet lid 19 and the optical system cooling duct 13 in the inside of the housing, an operator mistakenly attaches to the drive / control board unit 21 during replacement work. It can be prevented from touching and causing a failure.

  In addition, since the configuration in which the optical system cooling duct 13 is removed from the upper surface side of the housing is adopted, even when the projector is installed upside down and suspended from the ceiling, the replacement work can be easily performed.

  Each embodiment described above is only a representative example, and various modifications and changes can be made to each embodiment in carrying out the present invention.

  It is possible to provide an image projection apparatus such as a liquid crystal projector in which the optical elements inside the housing can be easily replaced.

DESCRIPTION OF SYMBOLS 1 Lamp 5 Projection lens barrel 6 Optical box 7 Optical box lid 13 Optical system cooling duct 18 Exterior cabinet 19 Cabinet lid 19a Duct holding part 19b Upper surface opening 19c Cover part 51 Wavelength selective phase difference plate β Decomposition / synthesis optical system

Claims (4)

A color separation / synthesis optical system that separates light from a light source into a plurality of color lights and guides them to a plurality of light modulation elements, and combines the plurality of color lights modulated by the plurality of light modulation elements to lead to a projection optical system;
An optical box containing the plurality of light modulation elements and the color separation / synthesis optical system;
A duct that is connected to a duct connection port of the optical box and guides cooling air to the light modulation element and the color separation / synthesis optical system;
A housing for housing the optical box and the duct;
The color separation / synthesis optical system includes a first optical element,
The inside of the housing, the optical box and the duct, said across the duct joint which opens in a first direction along the upper surface of the housing is arranged adjacent to each other physician,
The upper surface of the housing includes a cover portion that covers the upper surface of the optical box, a duct holding portion that removably holds the duct disposed inside the housing, and a second that is different from the first direction. the opening in the direction, has a top opening which allows removal from the interior of the housing of the duct removed from the duct holding section,
In a state where the duct is taken out from the inside of the housing, the first optical element is attached to and detached from the color separation / synthesis optical system inside the optical box through the duct connection port and the upper surface opening. An image projection apparatus characterized by that. An illumination optical system that guides light from the light source to the color separation / synthesis optical system is housed inside the optical box,
The illumination optical system includes a second optical element,
2. The image according to claim 1, wherein the second optical element is attached to and detached from the illumination optical system through the upper surface opening in a state where the duct is taken out from the inside of the housing. Projection device.   3. The image projection apparatus according to claim 2, wherein the duct includes a pressing portion that presses the second optical element against the optical box in a state where the duct is disposed inside the housing.   An electric circuit board on which an electric circuit for operating the image projection apparatus is mounted in a space other than the space between the upper surface opening and the duct inside the casing. The image projection apparatus as described in any one of Claim 1 to 3.