JP2008129507A - Rear projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rear projector with improved cooling efficiency of the housing inside. <P>SOLUTION: An air inlet port 111 and an air discharge port 118 are provided on the rear side of a lower housing 104 of the rear projector. The lower end of the discharge port 118 is disposed on the same line as the upper end of the inlet port 111 or above the upper end of the inlet port 111. Furthermore, when the discharge port 118 is disposed on the right side of the inlet port 111, the left end of the discharge port 118 is disposed on the same line as the right end of the inlet port 111 or on the right side of the right end of the inlet port 111. When the discharge port 118 is disposed on the left side of the inlet port 111, the right end of the discharge port 118 is disposed on the same line as the left end of the inlet port 111 or on the left side of the left end of the inlet port 111. Thereby, influence of the exhaust air on the intake is reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rear projector.

  A projection optical device that magnifies and projects an image formed by modulating the illumination light from a light source with a light valve such as a small LCD or a reflective mirror device onto a transmissive screen from the back side as one of the large televisions for home use. Interior projection televisions (rear projectors) are becoming popular. In recent years, in such a rear projection television, wide viewing angle, thinning, low height, and the like have become important. In order to widen the viewing angle, it is necessary to increase the luminance using a high-intensity light source having a large output. On the other hand, in order to reduce the thickness and height, it is necessary to reduce the size of the projection optical apparatus. However, when the projection optical apparatus is reduced in size and brightness, the internal heat generation density tends to increase.

  While there is a problem of heat generation as described above, the projection optical device contains many heat-sensitive parts such as a light valve, a rotary color filter, and a resin lens, and is kept at a low temperature. Therefore, high cooling efficiency is required. Moreover, since it is used in a general household, low noise is also required. From the above, it is important that the cooling device for cooling the projection optical device is small in size and has both high efficiency and low noise.

  In order to avoid a decrease in cooling efficiency of the rear projector, a rear projector having an intake port and an exhaust port provided on different side surfaces has been disclosed (see Patent Document 1).

JP 2006-208810 A

  In a rear projector described in Patent Document 1, a light source device and a power supply system are arranged on opposite sides of an optical system in a casing, and are arranged along a projection surface of a screen. The heat generated in the light source device is sucked out using a fan installed on the upper part of the light source device, and is exhausted from the exhaust port installed on the side surface of the housing. In this configuration, since the exhaust port is on the side surface of the housing, the exhaust is prevented from flowing around the back surface where the intake port exists.

  However, in a general home, a rear projector or the like is often arranged at a corner of the room, and in that case, the screen is arranged obliquely with respect to the wall surface. Since the air used for cooling the rear projector circulates from the side of the rear projector to the rear side and is guided to the air intake, the temperature is affected by the exhaust located on the side located below the air intake. As a result, the cooling efficiency deteriorates.

  Further, in the configuration of Patent Document 1, since it is necessary to suck out and exhaust the air inside the housing using a fan, there is a problem that the cooling efficiency is lower than in the case where the air is blown using the fan.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a rear projector having a high cooling efficiency that does not deteriorate the cooling efficiency in any installation form.

  A rear projector according to the present invention is disposed with a light source device, a light valve that modulates a light beam emitted from the light source device to form an image, an enlarged projection of the image, and a gap between the light source device and the light source device. Projection optical device, mirror for reflecting the light beam from the projection optical device, transmissive screen for projecting the light beam reflected by the mirror, the light source device, the light valve, the projection optical device, the mirror, A housing that houses the screen, an exhaust duct that is disposed inside the housing and in which the light source device is disposed, is provided on the back of the housing that faces the screen, and supplies cooling air to the projection optical device side An intake port provided on the back side of the housing and connected to the exhaust duct, wherein the lower end of the exhaust port is collinear with the upper end of the intake port, or When the exhaust port is located above the upper end of the air vent and the exhaust port is located on the right side of the intake port, the left end of the exhaust port is on the same line as the right end of the intake port or on the right side of the right end of the intake port When the exhaust port is located on the left side of the intake port, the right end of the exhaust port is located on the same line as the left end of the intake port or on the left side of the left end of the intake port. Is.

  According to the rear projector of the present invention, when the lower end of the exhaust port is collinear with or above the upper end of the intake port and the exhaust port is located on the right side of the intake port, If the left end of the exhaust port is on the same line as the right end of the intake port or on the right side of the right end of the intake port, and the exhaust port is positioned on the left side of the intake port, The rear projector is placed on the left side of the left end of the air intake, and the air intake and exhaust are located in the rear projector housing so that they do not overlap vertically and horizontally. Has the effect of improving. In addition, by improving the cooling performance, it is possible to reduce the number of rotations of the fan provided for cooling inside the housing, and there is an effect of reducing noise.

Embodiment 1 FIG.
Hereinafter, the rear projector according to the first embodiment of the present invention will be described.
FIG. 1 is a longitudinal sectional view of a rear projector 1 according to the first embodiment of the present invention. FIG. 1 is a cross-sectional view in a plane passing through the center of the screen 101 and perpendicular to the screen 101 screen. FIG. 2 is a cross-sectional view of a horizontal section at the height of the light source device 105 of the rear projector 1 as viewed from above. In FIG. 2, the intake port 111 and the exhaust port 118 are shown in the same cross-section for the sake of simplicity in describing the functions of the rear projector 1, but in reality, the heights at which they are arranged are different from each other and will be described later. As shown in FIG. 3, the intake port 111 is arranged so as to be located below the exhaust port 118.

  FIG. 3 is a rear side external view showing the rear external appearance of the rear projector 1. FIG. 4 is a vertical cross-section of a cross section passing through the light source device 105 of the rear projector 1 and perpendicular to the surface of the screen 101 as viewed from the light source side surface side of the rear projector in the direction in which light from the light source device 105 is emitted. It is a top view, and is a principal part sectional view showing the inside of exhaust duct 115 (details are mentioned below) especially. FIG. 5 is a longitudinal sectional view of the rear projector on a plane passing through the light source position and parallel to the screen 101. In each figure, the flow of cooling air is indicated by arrows.

The rear projector 1 reflects an optical image emitted from the projection optical device 107 by a mirror 102 and projects it onto a transmissive screen 101.
The housing of the rear projector 1 includes an upper housing 103 and a lower housing 104 that supports the upper housing 103 from below. A transmissive screen 101 is provided on one surface of the upper housing 103, a mirror 102 is held on the surface of the housing facing the screen, and a projection optical device 107 is connected to the bottom surface. The upper casing 103 together with the lower casing 104 and the projection optical device 107 constitutes a sealed space as a whole, and has a structure that prevents dust from entering the inside.

The transmissive screen 101 is configured using a Fresnel lens and a lenticular lens. The Fresnel lens converts the light beam emitted from the projection optical device 107, reflected by the mirror 102, and reaching the screen 101 into parallel light. The lenticular lens converts the light beam converted into parallel light by the Fresnel lens into diffused light so that an image on the screen 101 can be viewed from a wide angle.
An opening is provided on the upper surface of the lower housing 104, and a light beam emitted from the projection optical device 107 enters the upper housing 103 from this opening.

  On the back side facing the screen surface of the lower housing 104, an air inlet 111 is disposed. The air inlet 111 supplies the outside air to the light valve cooling fan 110 that cools the light valve 106 and the control circuit board 108 positioned on the projection optical device 107 side. Further, an exhaust port 118 connected to an exhaust duct 115 for exhausting heat generated from the light source device 105 is provided on the back side of the lower housing 104, and a lamp cover 120 for replacing the light source device 105 is further provided. Is provided. 2 and 3, an electric circuit cooling port 119 for supplying outside air to the electric circuit board 109 arranged on the left side in the case is arranged on the side surface of the case.

  In addition, in the rear projector rear side external view of FIG. 3, a square frame is described at the lower left in the drawing, and this frame indicates the arrangement of the input / output terminal boards. Also, in FIG. 3, arrows indicating the vertical and horizontal distances between the intake port 111 and the exhaust port 118 are described. The vertical arrows indicate the upper end of the intake port 111 and the lower end of the exhaust port 118. The vertical distance (height difference) is indicated by the arrows in the left and right directions, and the right end of the intake port 111 and the exhaust gas when the exhaust port 118 is disposed on the right side of the intake port 111 as illustrated in FIG. The distance in the horizontal direction from the left end of the mouth 118 (the positional deviation in the left-right direction) is shown.

  The projection optical device 107 is disposed at the center in the left-right direction in FIGS. 2 and 3, and includes an ultraviolet filter 301 that reflects ultraviolet rays that cause deterioration of the resin among the light beams emitted from the light source device 105, and an incident The rotary color filter 302 that separates the white light that has been separated, the integrator rod 303 that equalizes the in-plane light intensity distribution of the incident light beam, and the relay optical system 304 that guides the light beam emitted from the integrator rod 303 to the light valve 106. And a projection optical system 305 for enlarging and projecting an image generated by modulation by the light valve 106. In the projection optical apparatus 107, members that generate heat during operation are mainly an ultraviolet filter 301, a rotary color filter 302, and an integrator rod 303. These heat generating members are disposed in the vicinity of the light source device 105. .

  The light valve 106 used in the first embodiment is a device that forms pixels by driving a large number of minute mirrors, and generates an image from illumination light emitted from the relay optical system 304 in accordance with an input signal. However, this may be a small reflective liquid crystal panel or a transmissive liquid crystal panel.

  As shown in FIG. 2, the light source device 105 includes an arc tube 201, a reflecting mirror 203, a front glass 204 that seals an opening surface of the reflecting mirror 203, a reflecting mirror 203, and a lamp holder 205 that holds the front glass 204. The outer shape of the device 105 substantially corresponds to the outer shape of the lamp holder 205. Here, the reflecting mirror 203 is provided with notches 202 (two places) for introducing cooling air into the reflecting mirror 203 and discharging it outside, and the arc tube 201 is provided at the center of the reflecting mirror 203. It is a structure to hold. In addition, the reflecting mirror 203 collects the radiated light emitted from the arc tube 201 or makes it parallel light, so that the inner surface on the arc tube 201 side is a spheroid or paraboloid, or It is a close aspherical shape.

The front glass 204 is usually a glass flat plate, but it may have a lens shape. The light source device 105 is turned on and driven by a light source driving circuit 206 that receives power from the electric circuit board 109 and receives an input signal from the control circuit board 108.
The arc tube 201 is an ultra-high pressure mercury lamp in the present embodiment, but a discharge lamp such as a metal halide lamp or a xenon lamp may be used instead.
In this example, the light source device 105 is arranged on the right side in the left-right direction in FIGS.

  In order to cool the light source device 105, an exhaust duct 115 that includes the entire light source device 105 is disposed in the lower housing 104 (on the right side in FIGS. 2 and 3). As shown in FIG. 2 and FIG. 4, the exhaust duct 115 is provided with an inlet portion on the screen surface side in the lower housing 104, and from the intake port 111 on the back surface side of the lower housing 104. Further, it is structured to be connected to the exhaust port 118 arranged higher.

An exhaust fan 116 is held at the entrance of the exhaust duct 115 in the housing. The exhaust fan 116 sucks air inside the lower housing 104 (air introduced from the intake port 111 and the electric circuit cooling port 119) into the exhaust duct 115 and blows it as cooling air toward the light source device 105 side. Air (cooling air) heated by the light source device 105 is sent to the rear side of the housing, and is exhausted from the exhaust port 118 as exhaust to the outside of the housing.
Here, since the exhaust fan 116 requires a large air volume, it is desirable that the exhaust fan 116 be an axial fan having a large diameter as much as possible.

  Further, since the exhaust fan 116 is a large-diameter axial fan, the cooling air can be sent over a wider range. As shown in FIG. 2, a light source drive circuit 206 is arranged inside the exhaust duct 115, and a part of the air (cooling air) blown from the exhaust fan 116 is blown to the light source drive circuit 206. As a result, the light source drive circuit 206 can be cooled simultaneously with the cooling of the light source device 105. Since the air heated by the light source drive circuit 206 also passes through the exhaust duct 115 and is discharged from the exhaust port 118 to the outside of the housing, a dedicated cooling fan for cooling the light source drive circuit 206 is required. Therefore, highly efficient cooling is possible, and noise reduction associated therewith is also possible.

  Further, the air blown between the bottom surface of the light source device 105 (lamp holder 205) and the exhaust duct 115 is guided to the projection optical device cooling duct 117 disposed below the light source device 105 in the exhaust duct 115. The projection optical device cooling duct 117 guides the cooling air from the exhaust fan 116 to the gap between the projection optical device 107 and the light source device 105 through the opening on the bottom side of the gap. The cooling air guided to the gap portion cools the projection optical device 107 and is then discharged into the exhaust duct 115 through the opening on the upper surface side of the gap portion and discharged outside the housing through the exhaust port 118. Therefore, the projection optical apparatus 107 can be cooled with high efficiency. In FIG. 2, since the projection optical device cooling duct 117 is located below the light source device 105, the shape and the path of the cooling air are indicated by broken lines.

  In order to cool the arc tube 201, on the side of the reflecting mirror 203, a notch (opening) 202 provided in the vicinity of the front glass 204 (as shown in FIG. 2, an opening for introducing cooling air; and A lamp cooling fan 112 is connected to each other through a lamp cooling duct 113 provided with openings for discharging the air heated inside the reflecting mirror 203. Cooling air is blown into the inside of the lamp cooling fan 112 through the notch 202 of the reflecting mirror 203, and warmed air is supplied from the other notch 202 provided in the reflecting mirror 203 to the lamp holder 205. It is discharged inside, discharged from the grid (corresponding to the second grid) provided on the upper surface side of the lamp holder 205 to the inside of the exhaust duct 115, and discharged from the exhaust port 118 to the outside of the casing as exhaust. As will be described later, the exhaust port 118 is provided with a lattice (first lattice), and the intake port is similarly provided with a lattice or the like.

  As shown in FIG. 2, the lamp cooling fan 112 is connected to the optical engine cooling duct 114 disposed adjacent to the lamp cooling duct 113 described above, and the cooling air from the lamp cooling fan 112 is A gap between the projection optical device 107 and the light source device 105 (this gap is located in the exhaust duct 115) and a side surface (a surface on the side where cooling air from the lamp cooling fan 112 is introduced) ), The cooling air is sent through the opening, and the projection optical device 107 is cooled and then discharged out of the housing.

  The lamp cooling fan 112 is desirably a centrifugal fan such as a sirocco fan that can generate a high wind speed. The lamp cooling fan 112 sucks air in the lower housing 104 and supplies cooling air to the optical engine cooling duct 114 and the lamp cooling duct 113.

  In the lower housing 104, the air sucked by the exhaust fan 116 is sucked by the light valve cooling fan 110 from the air inlet 111 and has cooled the light valve 106 and the control circuit board 108 disposed on the projection optical device 107 side. And air that is sucked from the electric circuit cooling port 119 by the negative pressure generated by the exhaust fan 116 and the lamp cooling fan 112 to cool the electric circuit board 109. In this configuration, the air for cooling the electric circuit board 109 is used. A dedicated cooling fan is not required. Therefore, it can be said that it has a lower noise structure as compared with the case where a dedicated fan is used to introduce cooling air into the housing.

As shown in FIG. 3, the lower end of the exhaust port 118 described above is located on the same line as the upper end of the intake port 111 or above the upper end of the intake port 111. Therefore, even when the rear projector 1 is installed along the wall surface, the upward buoyancy generated by the exhaust gas that is heated and has a low specific gravity is generated by the intake port 111 located below the exhaust port 118. Therefore, high-temperature exhaust gas is less likely to be sucked into the intake port 111.
Furthermore, as shown in the figure, when the exhaust port 118 is disposed on the right side of the intake port 111, the left end of the exhaust port 118 is located on the same line as the right end of the intake port 111 or on the right side of the right end of the intake port 111. To do. Therefore, it is possible to suppress the intake of exhaust gas due to the influence of the high suction pressure portion near the center of the intake port 111.
In this way, the exhaust port 118 is positioned above the intake port 111, and they do not overlap in the vertical direction. Further, even when viewed in the left-right direction, they are arranged so as not to overlap. The influence of exhaust on the intake air can be reduced without depending on the arrangement in the room.

  As described above, the configuration in which the intake port 111 and the exhaust port 118 do not overlap in the vertical direction and the exhaust port 118 is disposed at a higher position, or the upper end of the intake port 111 and the lower end of the exhaust port 118 are disposed on the same line. With this configuration, the exhaust port 118 is disposed in the upper part of the exhaust duct 115, and the upper surface of the lamp holder 205 serving as the frame of the light source device 105 is placed at a position lower than the upper end of the exhaust port 118. It is burned. For this reason, the light leaking from the grating on the upper surface of the lamp holder 205 propagates to the exhaust port 118 side, and depending on the shape of the grid constituting the exhaust port 118, the light may leak out of the housing. Here, a lattice structure for preventing light leakage outside the housing will be described.

FIG. 6 is a sectional view (a section perpendicular to the screen surface) showing principally the exhaust port 118 and the light source device 105 in the first embodiment.
An exhaust port 118 is disposed on the back surface of the lower housing 104 extending in the vertical direction, and a first grid (horizontal grid) 118a extending in the horizontal direction is continuously provided in the exhaust port 118 at predetermined intervals in the vertical direction. Is arranged. The first grid 118a is formed by continuously arranging plate-like members extending in a horizontal direction with a predetermined width. In FIG. 6, the first grid 118a has a predetermined width (depth) of 20 mm and a grid interval of 8 mm. ing. The first grating 118a can limit the downward viewing angle to 22 ° or less from the horizontal plane. In other words, the dead angle is 68 degrees from the vertical plane.

  On the other hand, the opening at the top of the lamp holder 205 of the light source device 105 has a second extension extending in the same direction as the first grating 118a (in the horizontal direction and parallel to the screen surface (or the back of the housing)). A grid 205a is provided, and the second grid 205a is configured to have a height (corresponding to a depth) of 5 mm and an interval between the grids of 10 mm. When viewed from the inside of the light source device 105, the viewing angle in the rear side direction can be limited to 63 ° or less from the vertical plane, and therefore, the blind angle is 27 degrees or less from the horizontal plane. By combining these two lattices (118a, 205a), it is possible to create a state in which the inside of the light source device 105 cannot be seen from the outside of the housing, regardless of the positions of the exhaust port 118 and the light source device 105.

In addition, these grids are installed along the flow of the cooling air and sufficient openings are secured, so that the cooling efficiency is not lowered and the outside of the housing is connected through the exhaust port 118 from the inside of the light source device 105. It is possible to reduce the amount of light leaking to the light and effectively shield the light.
As shown in FIG. 6 described above, the grid 118a provided at the exhaust port 118 is not a straight member having a breadth in the depth (horizontal) direction, but has a height in the depth direction as shown in FIG. If the member has a cross-sectional shape that changes (waves), the light shielding performance can be changed depending on the wave shape.

Next, as a comparative example with the above-described lattice structure, the thickness (thickness) of the members constituting the exhaust port 118 and the lamp holder 205 for forming the lattice is used, and the thickness is the width in the depth direction of the lattice, Or the light-shielding state at the time of setting it as the width | variety in a height direction is demonstrated.
FIG. 7 is a cross-sectional view of the main part of the rear projector showing the same parts as in FIG. As shown in the drawing, the thickness of the lower housing 104 provided with the exhaust port 118 is usually 3 mm or less (here, 3 mm), and the interval between the horizontally extending lattices 118 b provided in the opening portion that becomes the exhaust port 118. Is 2 mm or less, the viewing angle from outside the housing is 27 degrees or less in the horizontal direction. On the other hand, the wall thickness of the lamp holder 205 is usually 2 mm or less (here, 2 mm). If the grating 205b is provided on the upper surface of the lamp holder 205 and has a spacing of 3 mm, the backward viewing angle is from the vertical plane. It will be 63 degrees or less. It can be seen that the combination of these gratings is the limit at which light leakage does not occur.

  However, in the above configuration, a sufficient opening area cannot be ensured and cooling is hindered. Therefore, it is necessary to increase the interval, but light leakage from the light source device 105 to the outside of the housing occurs. Accordingly, in order to suppress light leakage without hindering cooling, the lamp holder 205 facing the exhaust port 118 and having a depth (height) of 3 mm or more in the horizontal grid 118b on the exhaust port 118 side. It can be seen that the side grating 205b requires a height of 2 mm or more.

  As described above, the width in the depth direction of the first grid 118a extending in the horizontal direction provided in the exhaust port 118 is D1, the interval is L1, and the second lattice layer extends in a direction parallel to the exhaust port provided in the upper surface of the lamp holder 205. By securing a sufficient opening area between the interval D2 of the grating 205a and the width L2 in the height direction, the light source device has a relationship of arctan (L1 / D1) <arctan (D2 / L2). It can be seen that light leakage from the inside of the housing 105 to the outside of the housing (lower housing 104) is eliminated. Therefore, the light shielding efficiency can be increased by forming the first grating 118a and the second grating 205a so as to satisfy the above relationship.

  In the first embodiment of the present invention, the light source device 105 and the projection optical device 107 can be cooled with high efficiency, noise can be reduced, and the cooling efficiency is hardly lowered regardless of the installation state of the rear projector 1. The rear projector 1 that does not leak light from the light source device 105 to the outside of the housing (external housing 104) can be provided.

Embodiment 2.
Next, a rear projector according to the second embodiment of the present invention will be described.
FIG. 8 is a cross-sectional view showing a horizontal section of the rear projector 1 according to the second embodiment of the present invention at a height at which the light source device 105 is disposed.
The rear projector according to the second embodiment includes an electric circuit cooling fan 121 on the side surface of the electric circuit board 109 on the projection optical device 107 side in addition to the configuration of the first embodiment. With this electric circuit cooling fan 121, the air taken from the intake port 111 can be blown as cooling air to the electric circuit board 109 and discharged from the electric circuit cooling port 119. In the rear projector 1 having such a configuration, the electric circuit board 109 can be cooled with high efficiency by the electric circuit cooling fan 121 and the amount of heat exhausted by the exhaust fan 116 can be reduced. It is possible to lower. In addition, it is possible to reduce the burden on the exhaust fan 116 by obtaining a path for discharging the air that has cooled the electric circuit board 109 from the electric circuit cooling port 119 so that the exhaust fan 116 does not suck the air.

  FIG. 9 is a rear side external view showing the rear external appearance of the rear projector 1 according to the second embodiment of the present invention. As shown in FIG. 9, in consideration of the case where the rear projector 1 is installed in a corner of the room, in order to suppress the exhaust discharged from the power circuit cooling port 119 from affecting the intake port 111, The lower end of the circuit cooling port 119 is configured to be disposed above the intake port 111.

As described above, in the second embodiment of the present invention, by installing the electric circuit cooling fan 121 in the rear projector 1, the rotational speed of the exhaust fan 116 can be suppressed lower than that in the first embodiment. It is possible to reduce the noise such as the rotational noise generated in the exhaust fan 116, and the cooling efficiency can be improved by blowing the cooling air to the electric circuit board 109. Become.
In addition to the embodiment described above, it goes without saying that various modifications can be made without departing from the scope of the present invention.

1 is a longitudinal sectional view of a rear projector in a first embodiment. FIG. 2 is a transverse sectional view of the rear projector in the first embodiment. FIG. 2 is an external view of the rear side of the rear projector in the first embodiment. FIG. 6 is another longitudinal sectional view of the rear projector in the first embodiment. 6 is another longitudinal sectional view of the rear projector according to Embodiment 1. FIG. FIG. 3 is a cross-sectional view of a main part of the rear projector in the first embodiment. It is principal part sectional drawing of a rear projector required as a comparative example. FIG. 10 is a cross-sectional view of a rear projector in a second embodiment. FIG. 6 is a rear side external view of a rear projector according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rear projector 101 Screen 102 Mirror 103 Upper housing 104 Lower housing 105 Light source device 106 Light valve 107 Projection optical device 108 Control circuit board 109 Electrical circuit board 110 Light valve cooling fan 111 Inlet 112 Lamp cooling fan 113 Lamp cooling Duct 114 optical engine cooling duct 115 exhaust duct 116 exhaust fan 117 projection optical device cooling duct 118 exhaust port 118a first grid 119 electric circuit cooling port 120 lamp cover 121 electric circuit cooling fan 201 arc tube 202 notch 203 reflection Mirror 204 Front glass 205 Lamp holder 205a Second grating 206 Light source drive circuit 301 UV filter 302 Rotating color filter 303 Integrator rod 304 Relay light System 305 projection optical system.

Claims (5)

  A light source device, a light valve that modulates a light beam emitted from the light source device to form an image, a projection optical device that enlarges and projects the image, and is provided with a gap between the light source device and the projection optics A mirror for reflecting a light beam from the apparatus, a transmissive screen for projecting the light beam reflected by the mirror, the light source device, the light valve, the projection optical device, the mirror, a housing that houses the screen, An exhaust duct disposed in the housing and having the light source device disposed therein, an intake port provided on a back surface of the housing facing the screen, and supplying cooling air to the projection optical device side; An exhaust port provided on the back side and connected to the exhaust duct, the lower end of the exhaust port being located on the same line as the upper end of the intake port or above the upper end of the intake port; and When the exhaust port is located on the right side of the intake port, the left end of the exhaust port is on the same line as the right end of the intake port or on the right side of the right end of the intake port, and the exhaust port is located on the right side of the intake port. A rear projector, wherein when located on the left side, the right end of the exhaust port is located on the same line as the left end of the intake port or on the left side of the left end of the intake port.   An exhaust fan that is disposed in the casing and blows cooling air to the light source device side, and a projection optical device cooling duct that is disposed in the exhaust duct, and the exhaust fan is connected to the entrance side of the exhaust duct. Part of the cooling air sent from the exhaust fan is introduced into the projection optical device cooling duct in the exhaust duct, passes through the lower side of the light source device, and is located outside the exhaust duct. 2. The rear projector according to claim 1, wherein the rear projector is introduced into the gap provided between the optical device and the light source device, cools the projection optical device, and discharges the projection optical device to the exhaust port side.   A lamp cooling duct disposed in the exhaust duct, an optical engine cooling duct, a lamp cooling fan disposed in the housing and connected to the lamp cooling duct and the optical engine cooling duct; A part of the cooling air sent from the lamp cooling fan is introduced into the lamp cooling duct, sent to the reflecting mirror side constituting the light source device, and through an opening provided in the reflecting mirror. A part of the cooling air introduced into the reflecting mirror, discharged to the exhaust port side through another opening provided in the reflecting mirror, and sent from the lamp cooling fan is cooled by the optical engine cooling. The projection optical device is introduced into a gap provided between the projection optical device and the light source device, and the projection optical device is cooled and discharged to the exhaust port side. Rear projector of claim 2, wherein the.   The exhaust port has a structure in which a first grid having a predetermined width in the horizontal depth direction and a predetermined width in the horizontal depth direction is continuously arranged in the vertical direction with a predetermined interval in the rear surface of the casing. And a second grating extending in the same direction as the first grating and having a predetermined width in the vertical direction on the horizontal upper surface of the lamp holder which is the frame of the light source apparatus. Provided continuously with a predetermined interval in the direction perpendicular to the optical axis, and by adjusting the interval and width of the first and second gratings for the light from the light source device, blind spots are generated, and light is blocked. The rear projector according to claim 1, wherein:   The width of the first grid provided in the exhaust port is D1, the interval is L1, the width of the second grid provided in the lamp holder is L2, and the interval D2, and arctan (L1 / D1) <arctan ( 5. The rear projector according to claim 4, wherein the rear projector has a shape satisfying a relationship of D2 / L2).

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