JP5473310B2 - Image projection device - Google Patents

Description

  The present invention relates to an optical system used in an image projection apparatus such as a liquid crystal projector.

As an optical system of an image projection apparatus, a compact optical system configured so that the aspect ratio in the width direction and the depth direction of the apparatus is approximately 1: 1 has been conventionally proposed (see Patent Documents 1 and 2). . In addition, the projection lens is arranged in a direction perpendicular to the emission optical axis from the color separation / synthesis optical system after being reduced in size in a cross section orthogonal to the longitudinal direction of the apparatus, and parallel to the emission optical axis. An optical system in which light source lamps are arranged in various directions is also known (see Patent Document 3).
JP 2007-47799 A JP-A-2005-221980 JP 2003-207740 A

  The image projection apparatus is required to be further reduced in size and thickness as compared with the image projection apparatus using the optical system disclosed in Patent Documents 1 to 3. In particular, it is required not only to use the projector lens horizontally so that the optical axis of the projection lens extends in the horizontal direction, but also to enable vertical use with the light source lamp side down and the projection lens side up. ing.

Therefore, the present invention provides an image projection apparatus that can be more easily reduced in size and thickness than conventional ones .

An image projection apparatus according to an aspect of the present invention includes: a plurality of light modulation elements that perform image modulation on incident light; and a light from an ultra-high pressure mercury lamp that is divided into a plurality of light beams. An illumination optical system to be superimposed on the element, and the light from the illumination optical system is decomposed into a plurality of color lights, and the plurality of color lights are guided to the plurality of light modulation elements, and modulated by the plurality of light modulation elements A color separation / synthesis optical system for combining the plurality of color lights, a projection lens on which light synthesized by the color separation / synthesis optical system is incident, and light from the ultrahigh pressure mercury lamp is reflected toward the illumination optical system An image projection apparatus in which an optical system for image projection having a first reflection member that performs and a second reflection member that reflects light emitted from the projection lens toward a projection surface is housed inside the housing And the color separation / synthesis from the illumination optical system. Extend parallel to each other at a position where the extension line of the exit optical axis of the incident optical axis to the academic system from the color separating and synthesizing optical system to the projection lens is spaced apart from each other, an extension of the exit optical axis, the greater At least a part of the high-pressure mercury lamp is disposed, and the ultra-high pressure mercury lamp has an arc tube that emits light, and a reflector that guides divergent light from the arc tube toward the first reflecting member. The arc tube is disposed along a direction in which the reflector guides the diverging light to the first reflecting member, and an incident direction of light from the ultrahigh pressure mercury lamp to the first reflecting member; The incident direction of the light from the second reflecting member to the projection surface is parallel to each other, and the incident optical axis and the emission optical axis extend horizontally, and the incident optical axis and the emission Both in the second installation state where the optical axis extends vertically Oite, light from the light source lamp is characterized in that it is injected horizontally.

According to the present invention, the optical system is miniaturized in a cross section orthogonal to the incident optical axis from the illumination optical system to the color separation / synthesis optical system and the direction (longitudinal direction) of the emission optical axis from the color separation / synthesis optical system to the projection lens , and It is possible to realize an image projection apparatus capable of arranging a light source lamp that emits light by discharge in both the first and second installation states (horizontal installation state and vertical installation state) so as to emit light horizontally. . And it becomes possible to form the whole image projection apparatus including the housing | casing which accommodates this in the elongate shape (for example, square prism shape) in the said longitudinal direction.

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

  FIG. 1 shows the configuration of an image projection apparatus 100 using an image projection optical system that is Embodiment 1 of the present invention.

  The light emitted from the light source lamp 1 is reflected by the first mirror (first reflecting member) 50 and travels toward the illumination optical system α. The light that has passed through the illumination optical system α is emitted from the projection lens 2 via the color separation / synthesis optical system βa and a liquid crystal panel (light modulation element) not shown in FIG. The light emitted from the projection lens 2 is reflected by the second mirror (second reflecting member) 3 and projected onto a projection surface such as a screen or a wall surface (not shown).

  As the first and second reflecting members, members other than a mirror such as a prism can be used.

Here, in the optical system for image projection of the present embodiment,
(1) An incident optical axis L1 from the illumination optical system α to the color separation / synthesis optical system βa and an extension line L2 ′ of the emission optical axis L2 from the color separation / synthesis optical system βa to the projection lens 2 are a predetermined distance D from each other. They extend parallel to each other at spaced positions. In other words, the incident optical axis L1 and the outgoing optical axis L2 may extend in parallel to each other at a position separated by a predetermined distance D from each other.

  (2) Further, at least a part of the light source lamp 1 is disposed on an extension line (on L2 ′) of the emission optical axis L2.

  (3) Further, the incident direction of light from the light source lamp 1 to the first mirror 50 (in other words, the incident optical axis L3) and the emission direction of light from the second mirror 3 to the projection surface (in other words, emission) The optical axes L4) are parallel to each other.

  In this embodiment, the light incident direction from the light source lamp 1 to the first mirror 50 and the light emitting direction from the second mirror 3 to the projection surface are opposite to each other.

  By satisfying the arrangement conditions described in the above (1) to (3), the optical system for image projection is long in the direction of the incident optical axis L1 and the outgoing optical axis L2, and is a cross section orthogonal to the direction. Can be combined into an elongated shape with a small size, that is, downsizing and thinning can be achieved. Therefore, the optical system for image projection can be accommodated inside the elongated rectangular columnar casing 100 whose longitudinal direction is the direction of the incident optical axis L1 and the outgoing optical axis L2.

  In this embodiment, the light emission direction (incident optical axis L3) from the light source lamp 1 is a direction orthogonal to the incident optical axis L1 from the illumination optical system α to the color separation / synthesis optical system βa. Thereby, the size in the longitudinal direction of the optical system for image projection can also be reduced.

  In addition, in this embodiment, the exhaust fan 6 provided mainly for cooling the light source lamp 1 is disposed so that the rotation axis of the exhaust fan 6 is parallel to the incident optical axis L1 and the outgoing optical axis L2. doing. In other words, the exhaust fan 6 is disposed such that the direction in which the rotation axis extends is orthogonal to the direction of light emission from the light source lamp 1 (incident optical axis L3). The air discharge port 7 from the exhaust fan 6 is provided on the end face in the longitudinal direction of the casing 100, and the air that has cooled the light source lamp 1 is discharged in the longitudinal direction of the casing 100. In addition, it can be said that the exhaust fan 6 is disposed at least partially on the extended line L2 ′ of the emission optical axis L2 in the same manner as the light source lamp 1.

  With the arrangement of the fan 7 as described above, the light source lamp 1 can be efficiently cooled while the size of the casing 100 (that is, the image projection apparatus) is reduced in the longitudinal direction.

  “Parallel” or “orthogonal” in this embodiment does not need to be completely parallel or orthogonal, and has a slight deviation within a range that can be regarded as substantially parallel or orthogonal (for example, a deviation of about 10 degrees). )including.

  In the present embodiment, the “incident optical axis” and “emitted optical axis” are projections projected on the projection surface through the center of the image display surface of the liquid crystal panel among the light emitted from the light source lamp 1. This corresponds to an optical path followed by a light ray reaching the center of the image (central angle of view principal ray).

  Furthermore, the angle of the second mirror 3 may be changed so that the light emission direction to the projection surface can be adjusted. Also in this case, the angle of the second mirror 3 in which the light incident direction from the light source lamp 1 to the first mirror 50 and the light emitting direction from the second mirror 3 to the projection surface are parallel can be selected. If so, the above arrangement condition (3) is satisfied.

  Reference numeral 4 denotes a first power supply unit that supplies lighting power to the light source lamp 1, and reference numeral 5 denotes a second power supply unit that supplies power to electrical components or electrical circuits other than the light source lamp 1. These power supply units 4 and 5 are arranged between the light source lamp 1 and the second mirror 3 inside the housing 100 so as to be parallel to the incident optical axis L1 and the outgoing optical axis L2. Furthermore, the power supply units 4 and 5 are arranged in a space between the surface (side surface) extending in the longitudinal direction of the housing 100 and the color separation / synthesis optical system βa and the projection lens 2. And it arrange | positions so that at least one of the projection lenses 2 may be met (closely).

  With such an arrangement, the size of the cross section orthogonal to the longitudinal direction of the casing 100 housing the image projection optical system and the power supply units 4 and 5 can be reduced. Of course, electric circuit boards (not shown) other than the power supply units 4 and 5 may be similarly arranged.

Next, a more specific configuration and optical action of the optical system for image projection will be described. The light source lamp 1 is a high-intensity light source such as an ultra-high pressure mercury lamp, and includes an arc tube that emits white light by discharge and a reflector that collects divergent light from the arc tube in a predetermined direction.

  FIG. 2 shows the configuration of the illumination optical system α. The light from the light source lamp 1 is reflected by the first mirror 50 and enters the illumination optical system α.

  In the illumination optical system α, reference numeral 51a denotes a first cylinder array having a plurality of cylindrical lenses having refractive power in a direction parallel to the paper surface of FIG. 2 (a direction perpendicular to the paper surface of FIG. 1; hereinafter referred to as a horizontal direction). . Reference numeral 51b denotes a second cylinder array having a plurality of cylindrical lenses corresponding to the plurality of cylindrical lenses of the first cylinder array 51a. 52 is an ultraviolet absorption filter. A polarization conversion element 53 converts non-polarized light from the light source lamp 1 into linearly polarized light having a predetermined polarization direction (converts P-polarized light into S-polarized light).

  Reference numeral 54 denotes a front compressor constituted by a cylindrical lens having a refractive power in a direction perpendicular to the paper surface of FIG. 2 (a direction parallel to the paper surface of FIG. 1; hereinafter referred to as a vertical direction). Reference numeral 51c denotes a third cylinder array having a plurality of cylindrical lenses having refractive power in the vertical direction. Reference numeral 51d denotes a fourth cylinder array having a plurality of cylindrical lenses corresponding to the plurality of cylindrical lenses of the third cylinder array 51c.

  Reference numeral 55 denotes a color filter that acts to return light in a specific wavelength range to the light source lamp 1 in order to adjust the color coordinates. Reference numeral 56 denotes a condenser lens. Reference numeral 57 denotes a rear compressor composed of a cylindrical lens having a refractive power in the vertical direction.

  The illumination optical system α configured as described above divides the light from the light source lamp 1 into a plurality of light beams, and superimposes the light beams on each liquid crystal panel (each light modulation element) to be described later. Has a function of uniformly illuminating the light.

  FIG. 3 shows the configuration of the color separation / synthesis optical system βa. In the color separation / synthesis optical system βa, reference numeral 60 denotes a dichroic mirror that reflects light in the blue (B) and red (R) wavelength regions and transmits light in the green (G) wavelength region. Reference numeral 61 denotes a G-use incident side polarizing plate formed by attaching a polarizing element to a transparent substrate and transmits only P-polarized light. A first polarization beam splitter 62 transmits P-polarized light and reflects S-polarized light, and has a polarization separation surface.

  Reference numerals 63R, 63G, and 63B respectively denote an R reflective liquid crystal panel, a G reflective liquid crystal panel, and a B reflective liquid crystal panel (hereinafter simply referred to as light modulation elements) that modulate and reflect incident light. A liquid crystal panel) and displays an original image for image modulation. 64R, 64G, and 64B are a quarter wavelength plate for red, a quarter wavelength plate for green, and a quarter wavelength plate for blue, respectively. A trimming filter 65a acts to return orange light to the light source lamp 1 in order to increase the color purity of R.

  Reference numeral 65b denotes an incident-side polarizing plate for RB configured by attaching a polarizing element to a transparent substrate, and transmits only P-polarized light. Reference numeral 66 denotes a color selective phase difference plate that converts the polarization direction of the R light by 90 degrees and does not convert the polarization direction of the B light. Reference numeral 67 denotes a second polarization beam splitter that transmits P-polarized light and reflects S-polarized light, and has a polarization separation surface.

  68B is an exit side polarizing plate for B, and rectifies only S-polarized light out of B light. 68G is an exit side polarizing plate for G that transmits only S-polarized light. Reference numeral 69 denotes a dichroic prism that transmits R light and B light and reflects G light.

  The color separation / synthesis optical system βa configured in this way decomposes the light from the illumination optical system α into a plurality of color lights (R light, G light, and B light), and converts the plurality of color lights into a plurality of liquid crystal panels 63R, Guide to 63G, 63B. Further, the plurality of color lights image-modulated by the plurality of liquid crystal panels 63R, 63G, and 63B are combined and guided to the projection lens 2.

  Although the polarization conversion element 53 is described as converting P-polarized light into S-polarized light, the P-polarized light and S-polarized light described here are based on the polarization conversion element 53. On the other hand, light incident on the dichroic mirror 60 is assumed to be incident on P-polarized light with the first and second polarization beam splitters 62 and 67 as a reference. That is, the light emitted from the polarization conversion element 53 is S-polarized light, but the same S-polarized light that enters the dichroic mirror 60 is called P-polarized light.

  Next, the optical action will be described. The light emitted from the arc tube of the light source lamp 1 is condensed in a predetermined direction by the reflector to become a parallel light flux. The parallel light beam is reflected by approximately 90 degrees by the first mirror 50 and enters the first cylinder array 51a. The light beam incident on the first cylinder array 51a is divided into a plurality of light beams by a plurality of cylindrical lenses and is collected. The plurality of light beams form a plurality of light source images in the vicinity of the polarization conversion element 53 through the ultraviolet absorption filter 52 and the second cylinder array 51b.

  Each of the polarization conversion elements 53 includes a plurality of polarization separation surfaces, a reflection surface, and a half-wave plate, and the plurality of light beams are incident on a polarization separation surface corresponding to the column, and the polarization separation surfaces are P-polarized light that is transmitted and S-polarized light that is reflected by the polarization separation surface are separated. The S-polarized light reflected by the polarization separation surface is reflected by the reflecting surface and is emitted in the same direction as the P-polarized light. On the other hand, the P-polarized light transmitted through the polarization separation surface is converted into S-polarized light by the half-wave plate and emitted. Thereby, the non-polarized light from the light source lamp 1 is emitted as linearly polarized light which is S-polarized light.

  A plurality of light beams from the polarization conversion element 53 enter the third cylinder array 51 c via the front compressor 54. Each light beam incident on the third cylinder array 51c is divided into a plurality of light beams by a plurality of cylindrical lenses of the third cylinder array 51c and condensed, and the plurality of light beams pass through the fourth cylinder array 51d. . The plurality of light beams thus divided in the horizontal direction and the vertical direction reach the condenser lens 56 and the rear compressor 57.

  Due to the optical action of the front compressor 54, the condenser lens 56 and the rear compressor 57, a plurality of light beams are superimposed on each other. Thereby, a rectangular illumination area having a uniform intensity is formed. Each liquid crystal panel is arranged in this illumination area.

  The light converted to S-polarized light by the polarization conversion element 53 enters the dichroic mirror 60. As described above, the dichroic mirror 60 reflects light in the B wavelength region (430 to 495 nm) and light in the R wavelength region (590 to 650 nm) and transmits light in the G wavelength region (505 to 580 nm). To do.

  First, the G optical path will be described. The G light transmitted through the dichroic mirror 60 enters the incident side polarizing plate 61. The G light remains P-polarized light (S-polarized light when the polarization conversion element 53 is used as a reference) even after being transmitted through the dichroic mirror 60.

  The G light exits from the incident-side polarizing plate 61, then enters the first polarizing beam splitter 62 as P-polarized light, passes through the polarization separation surface, and reaches the G liquid crystal panel 63G. In the G liquid crystal panel 63G, the G light is image-modulated and reflected. Of the image-modulated G light, P-polarized light is transmitted again through the polarization separation surface of the first polarization beam splitter 62, returned to the light source lamp side, and removed from the projection light. On the other hand, the S-polarized light of the image-modulated G light is reflected by the polarization separation surface of the first polarization beam splitter 62 and travels toward the dichroic prism 69 as projection light.

  The G light reflected by the first polarization beam splitter 62 enters the dichroic prism 69 as S-polarized light, is reflected by the dichroic surface of the dichroic prism 69, and reaches the projection lens 2.

  On the other hand, the R light and B light reflected by the dichroic mirror 60 are incident on the incident-side polarizing plate 65b after the orange light is cut by the trimming filter 65a. The R light and B light are still P-polarized light after being reflected by the dichroic mirror 60. The R light and B light emitted from the incident side polarizing plate 65 b are incident on the color selective phase difference plate 66.

  The color selective phase difference plate 66 has an effect of rotating only the polarization direction of the R light by 90 degrees. By this. The R light is emitted as S-polarized light and the B light is emitted as P-polarized light, and enters the second polarizing beam splitter 67. The R light incident on the second polarization beam splitter 67 as S-polarized light is reflected by the polarization separation surface of the second polarization beam splitter 67 and reaches the R liquid crystal panel 63R. The B light incident on the second polarization beam splitter 67 as P-polarized light passes through the polarization separation surface of the second polarization beam splitter 67 and reaches the B liquid crystal panel 63B.

  The R light incident on the R liquid crystal panel 63R is image-modulated and reflected. Of the image-modulated R light, S-polarized light is reflected again by the polarization separation surface of the second polarization beam splitter 67, returned to the light source lamp side, and removed from the projection light. On the other hand, P-polarized light out of the image-modulated R light passes through the polarization separation surface of the second polarization beam splitter 67, passes through the dichroic surface of the dichroic prism 69 as projection light, and reaches the projection lens 2.

  The B light incident on the B liquid crystal panel 63B is image-modulated and reflected. Of the image-modulated B light, P-polarized light is transmitted again through the polarization separation surface of the second polarization beam splitter 67, returned to the light source lamp side, and removed from the projection light. On the other hand, the S-polarized light of the image-modulated B light is reflected by the polarization separation surface of the second polarization beam splitter 67 and analyzed by the exit-side polarizing plate 68B, and then the dichroic surface of the dichroic prism 69 as projection light. Is transmitted to the projection lens 2.

  The R light, G light, and B light combined by the dichroic prism 69 in this way are emitted from the projection lens 2, reflected by the second mirror 3, and enlarged and projected onto the projection surface.

Note that FIG. 1 illustrates the image projection apparatus 100 in a vertically installed state (second installation state) in which the longitudinal direction extends vertically (the second mirror 3 is disposed on the upper side and the light source lamp 1 is disposed on the lower side ) . It shows how it is used. In this case, although not shown, it is preferable to use an installation table such as a rack for smoothly exhausting the exhaust from the exhaust fan 6 or to provide a duct for guiding the exhaust from the exhaust fan 6 to the side.

FIG. 4 shows a state in which the image projection apparatus 100 shown in FIG. 1 is used in a horizontally placed state (first installed state) in which the longitudinal direction extends left and right (horizontal) .

As described above, according to the present embodiment, the light source lamp 1 that can be used in both the vertical and horizontal positions and emits light by discharge in both the vertical and horizontal positions as shown in FIGS. It is possible to realize a small-sized image projection apparatus that can be arranged so as to emit horizontally .

FIG. 5 shows a modified example (reference technical example) of the image projection apparatus of FIG. In this modification, the second mirror 203 is disposed so as to reflect light in the opposite direction to the second mirror 3 shown in FIG. Also in this case, the arrangement conditions (1) to (3) described above are satisfied.

  Further, the position and orientation of the light source lamp 1 shown in FIG. 1 may be changed as shown in FIGS. Although the case where the light from the light source lamp 1 facing the direction of the first mirror 50 is directly incident on the first mirror 50 has been described with reference to FIG. 1, the light from the light source lamp 1 is not illustrated in FIGS. After being reflected by the third mirror 51, it is reflected by the first mirror 50 and enters the illumination optical system α. The emission direction of light from the light source lamp 1 is parallel to the incident optical axis L1 and the outgoing optical axis L2 (L2 ′). Even in the configurations shown in these drawings, the arrangement conditions (1) to (3) described above are satisfied.

  FIG. 6 shows the configuration of an image projection apparatus using an image projection optical system that is Embodiment 2 of the present invention. In the first embodiment, an image projection apparatus using a reflective liquid crystal panel has been described. In this embodiment, a transmissive liquid crystal panel is used. For this reason, the configuration of the color separation / synthesis optical system βb is different from that of the color separation / synthesis optical system βa of the first embodiment. Since the constituent elements other than the color separation / synthesis optical system βb are the same as those in the first embodiment, these constituent elements are denoted by the same reference numerals as those in the first embodiment, and the description thereof is omitted.

  The configuration of the color separation / synthesis optical system βb in this embodiment will be described with reference to FIG. The plurality of light beams divided by the illumination optical system α are incident on the first dichroic mirror 360 and pass through the first dichroic mirror 360 and the light including R light and G light reflected by the first dichroic mirror 360. It is decomposed into B light. The light including G light and R light is split by the second dichroic mirror 370 into G light reflected here and R light transmitted therethrough.

  The R light is reflected by the two mirrors 371, and further passes through the field lens 373R to illuminate an R transmissive liquid crystal panel (light modulation element: hereinafter simply referred to as a liquid crystal panel) 363R. The R light image-modulated by the R liquid crystal panel 363R is reflected by the color synthesis prism 374 and enters the projection lens 2.

  The G light is transmitted through the field lens 373G and illuminates the transmissive liquid crystal panel 363G for G. The G light subjected to image modulation by the G liquid crystal panel 363G passes through the color synthesis prism 374 and enters the projection lens 2.

  The B light is reflected by the mirror 372, passes through the field lens 373B, and illuminates the transmissive liquid crystal panel 363B for B. The B light image-modulated by the B liquid crystal panel 363 </ b> B is reflected by the color synthesis prism 374 and enters the projection lens 2.

  The light from the three liquid crystal panels 363R, 363G, and 363B synthesized by the color synthesizing prism 374 is emitted from the projection lens 2, reflected by the second mirror 3, and enlarged and projected onto the projection surface.

  Also in this embodiment, the arrangement conditions (1) to (3) described in the first embodiment are satisfied. Accordingly, the image projection optical system can be combined into an elongated shape that is long in the direction of the incident optical axis L1 and the exit optical axis L2 and small in size in a cross section orthogonal to the direction.

  However, in this embodiment, the size of the color separation / synthesis optical system βb in the cross section is larger than that of the color separation / synthesis optical system βa of the first embodiment. Therefore, the first and second power supply units 4 and 5 are respectively connected between the light source lamp 1 and the color separation / combination optical system βb and between the light source lamp 1 and the second mirror 3 and the color separation / combination optical system. It arrange | positions separately between (beta) b and the 2nd mirror 3. FIG. Thereby, it is not necessary to make the size of the cross section orthogonal to the longitudinal direction of the housing 300 much larger than that of the color separation / synthesis optical system βb. Therefore, also in the present embodiment, the housing 300 can be formed in a quadrangular prism shape elongated in the longitudinal direction.

  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.

  For example, in each of the above-described embodiments, the case where the reflective and transmissive liquid crystal panels are used as the light modulation elements has been described. However, instead of these, a digital micromirror device (DMD) may be used.

1 is a diagram illustrating a configuration of an image projection apparatus using an image projection optical system that is Embodiment 1 of the present invention. FIG. FIG. 3 is a diagram illustrating a configuration of an illumination optical system in the image projection optical system according to the first embodiment. FIG. 3 is a diagram illustrating a configuration of a color separation / synthesis optical system in the image projection optical system according to the first embodiment. FIG. 3 is a diagram illustrating a state in which the image projection apparatus according to the first embodiment is placed horizontally. FIG. 6 is a diagram illustrating a modification of the first embodiment. The figure which shows the structure of the image projection apparatus using the optical system for image projection which is Example 2 of this invention. FIG. 6 is a diagram illustrating a configuration of a color separation / synthesis optical system in the image projection optical system according to the second embodiment. FIG. 6 is a diagram illustrating another modification of the first embodiment. FIG. 6 is a diagram showing still another modification of the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source lamp 2 Projection lens 3 2nd mirror 50 1st mirror 4 1st power supply unit 5 2nd power supply unit 6 Exhaust fan 7 Exhaust port 53 Polarization conversion element 63R, 63G, 63B Reflective type liquid crystal panel 100,300 Housing 363R, 363G, 363B Transmission type liquid crystal panel L1 Incident optical axis L2 Ejecting optical axis

Claims (4)

A plurality of light modulation elements for image-modulating incident light;
An illumination optical system that divides the light from the ultra-high pressure mercury lamp into a plurality of light fluxes and superimposes the plurality of light fluxes on each of the light modulation elements;
Color separation / synthesis that separates light from the illumination optical system into a plurality of color lights, guides the plurality of color lights to the plurality of light modulation elements, and combines the plurality of color lights modulated by the plurality of light modulation elements Optical system,
A projection lens on which light synthesized by the color separation / synthesis optical system is incident;
A first reflecting member that reflects light from the ultra-high pressure mercury lamp toward the illumination optical system;
An image projection apparatus in which an optical system for image projection having a second reflecting member that reflects light emitted from the projection lens toward a projection surface is housed in a housing,
An incident optical axis from the illumination optical system to the color separation / synthesis optical system and an extension line of an emission optical axis from the color separation / synthesis optical system to the projection lens extend in parallel with each other at positions spaced apart from each other,
On the extended line of the emission optical axis, at least a part of the ultra-high pressure mercury lamp is disposed,
The ultra-high pressure mercury lamp has an arc tube that emits light, and a reflector that guides divergent light from the arc tube toward the first reflecting member,
The arc tube is disposed along a direction in which the reflector guides the diverging light to the first reflecting member;
An incident direction of light from the ultrahigh pressure mercury lamp to the first reflecting member and an emitting direction of light from the second reflecting member to the projection surface are parallel to each other,
In both the first installation state where the incident optical axis and the emission optical axis extend horizontally and the second installation state where the incident optical axis and the emission optical axis extend vertically, light from the ultrahigh pressure mercury lamp is horizontal. An image projecting apparatus, wherein 2. The image according to claim 1, wherein the fan that cools the ultra-high pressure mercury lamp is arranged so that a rotation axis of the fan is parallel to the incident optical axis and the emission optical axis. Projection device. Between the ultrahigh pressure mercury lamp and the second reflecting member inside the casing, a power supply unit is parallel to the incident optical axis and the emission optical axis, and the casing and the color separation / synthesis The image projection apparatus according to claim 1, wherein the image projection apparatus is disposed along at least one of an optical system and the projection lens.   4. The image projection apparatus according to claim 1, wherein the casing has a quadrangular prism shape whose longitudinal direction is the direction of the incident optical axis and the outgoing optical axis. 5.