JP2010085804A - Image projection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image projection device in which a polarization conversion element can efficiently be cooled without interrupting effective light rays, and also noise can be suppressed. <P>SOLUTION: The image projection device includes: the polarization conversion element 45 which converts non-polarized light made incident from a light source 1 into linear polarization; optical systems α, β and 5 which produce light for illuminating an image forming element 61 by using the linear polarization and project the light modulated by the image forming element onto a surface to be projected; and cooling means 14, 15, 16 and E which supply cooling air to the incident surface of the polarization conversion element. The cooling means supply the cooling air to the first area B where the non-polarized light enters the inside of the polarization conversion element, of the incident surface from a specific direction along the incident surface. A heat dissipating member 70 is provided in the second area A of the incident surface which is an area where the non-polarized light does not enter a part except a polarization splitting surface 45a inside the polarization conversion element and away from the center part C of a flow of cooling air in a direction perpendicular to the specific direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image projection apparatus such as a liquid crystal projector, and more particularly to an image projection apparatus having a polarization conversion element and a structure for cooling the polarization conversion element.

  In some cases, a projector uses a polarization conversion element that converts non-polarized light incident from a light source into linearly polarized light. The linearly polarized light is separated into a plurality of color lights by a color separation / synthesis optical system configured by a polarization beam splitter or the like, and the plurality of color lights are guided to a plurality of image forming elements (liquid crystal panels or the like). Furthermore, the plurality of color lights modulated by the plurality of image forming elements are synthesized by the color separation / synthesis optical system and projected onto the projection surface.

  Due to the downsizing and light intensity of the projector, the intensity of light that hits a unit area of the polarization conversion element increases, and the performance deterioration of the polarization conversion element due to temperature rise has become a problem.

  For cooling the polarization conversion element, as disclosed in Patent Document 1, a part of cooling air from the fan to the liquid crystal panel or the light source lamp is often branched and used. However, when the polarization conversion element is cooled by the cooling air sent from the fan, since the cooling air has directivity, the cooling is biased, and there is a portion where the cooling is insufficient in the incident surface of the polarization conversion element. Further, if it is attempted to eliminate the above-mentioned insufficient cooling portion by increasing the cooling air volume, the size of the projector and the increase in noise are caused by the increase in the size of the fan and the number of revolutions.

  In Patent Document 2 and Patent Document 3, by providing a heat transfer transparent substrate with high thermal conductivity on the exit side of the polarization conversion element, heat transfer and heat dissipation are efficiently performed, and performance deterioration of the polarization conversion element due to heat is prevented. A projector is disclosed.

Patent Document 4 discloses a plurality of regions between a plurality of incident regions in which light from a light source lamp is incident toward a plurality of polarization separation surfaces among incident surfaces of a polarization conversion element using a plurality of polarization separation surfaces. A polarization conversion element provided with a light shielding member having a plurality of light shielding portions for shielding light is disclosed.
JP 2001-228803 A JP 2002-006281 A JP 2001-318359 A Japanese Patent No. 3832076

  However, as disclosed in Patent Document 2 and Patent Document 3, a heat transfer transparent substrate (for example, sapphire) having a high thermal conductivity is generally expensive. Further, since the thermal conductivity of sapphire is about 40 W / K · m, the heat transfer / heat radiation effect as high as that of a metal having a high thermal conductivity such as aluminum cannot be expected.

  Further, in the configuration in which a plurality of regions between a plurality of incident regions are shielded by a plurality of light shielding portions (light shielding members) as in the polarization conversion element disclosed in Patent Document 4, the polarization conversion element and the light shielding member It is difficult to align. When the light shielding portion covers a part of the incident area, a part of the effective light that should be incident on the incident area is blocked, resulting in a problem that the projected image becomes dark.

  The present invention provides an image projection apparatus capable of efficiently cooling a polarization conversion element without blocking effective light and suppressing noise.

  An image projection apparatus according to one aspect of the present invention uses a polarization separation surface to convert a non-polarized light incident from a light source into linearly polarized light, and light that illuminates an image forming element using the linearly polarized light. And an optical system that projects the light modulated by the image forming element onto the projection surface, and a cooling unit that supplies cooling air to the incident surface of the polarization conversion element. The cooling unit supplies cooling air from a specific direction along the incident surface to a first region of the incident surface where non-polarized light is incident on the inside of the polarization conversion element. And it is a region where the non-polarized light is not incident on the part other than the polarization separation surface inside the polarization conversion element, and is separated from the center of the flow of the cooling air in the direction perpendicular to the specific direction. A heat dissipation member is provided on the second region.

  An image projection apparatus according to another aspect of the present invention generates a polarization conversion element that converts non-polarized light incident from a light source into linearly polarized light, and light that illuminates the image forming element using the linearly polarized light. An optical system that projects light modulated by the image forming element onto a projection surface, a cooling unit that supplies cooling air to the incident surface of the polarization conversion element, and an incident surface of the polarization conversion element. And a heat dissipating member. The cooling means includes a fan and an air guide path that guides the cooling air from the fan to be supplied to a first region of the incident surface where non-polarized light is incident on the inside of the polarization conversion element. And a heat radiating member has an extension part extended in the inside of an air guide path, It is characterized by the above-mentioned.

  According to the present invention, it is possible to efficiently cool the region away from the center of the flow of the cooling air on the incident surface of the polarization conversion element by the heat radiating member. Therefore, the entire polarization conversion element can be appropriately cooled. In addition, it is not necessary to increase the size of the fan or increase the number of rotations, so that an increase in noise can be avoided. Further, it is difficult to cause a problem of blocking effective light incident on the polarization conversion element.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(Overall configuration of projector)
FIG. 2 shows the configuration of a liquid crystal projector (image projection apparatus) that is Embodiment 1 of the present invention.

  In this figure, 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, as the light source lamp 1, a discharge lamp (for example, a halogen lamp, a xenon lamp, or a metal halide lamp) other than the high-pressure mercury discharge lamp may be used.

  2 is a lamp holder for holding the lamp 1, 3 is explosion-proof glass, and 4 is a glass presser. α is an illumination optical system that converts the luminous flux from the lamp 1 into a parallel luminous flux having a uniform brightness distribution, β is a color separation of the light from the illumination optical system α, and is applied to a liquid crystal panel for RGB, which will be described later. A color separation / synthesis optical system for guiding and color-combining light from the liquid crystal panel.

  Reference numeral 5 denotes a projection lens that projects light (image) from the color separation / synthesis optical system β onto a screen (projected surface) (not shown). A projection optical system, which will be described later, is accommodated in the projection lens 5.

  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 5 is fixed. The optical box 6 is formed with a lamp case 6 a surrounding the lamp 1.

  Reference numeral 7 denotes an optical box lid that covers the optical box 6 with the illumination optical system α and the color separation / synthesis optical system β accommodated therein. Reference numeral 8 denotes a PFC power supply board that creates a DC power supply from a commercial power supply to each board. Reference numeral 9 denotes a power supply filter board. Reference numeral 10 denotes a ballast power supply board that operates with the PFC power supply board 8 to drive the lamp 1 to light.

  Reference numeral 11 denotes a control board that performs driving of the liquid crystal panel and lighting control of the lamp 1 by electric power from the PFC power supply board 8. 12A and 12B are first and second for cooling optical elements such as a liquid crystal panel and a polarizing plate in the color separation / synthesis optical system β by sucking air from an air inlet 21a of the lower exterior case 21 described later. It is an optical system cooling fan. Reference numeral 13 denotes a first RGB duct for guiding the wind from both the optical system cooling fans 12A and 12B to the optical elements in the color separation / synthesis optical system β.

  Reference numeral 14 denotes a lamp cooling fan that sends a blowing air to the lamp 1 to cool the lamp 1. A first lamp duct 15 guides the cooling air to the lamp 1 while holding the lamp cooling fan 14. Reference numeral 16 denotes a second lamp duct that holds the lamp cooling fan 14 and forms a duct together with the first lamp duct 15.

  Reference numeral 17 denotes a power supply cooling fan for cooling air by sucking air from an air inlet 21b provided in the lower exterior case 21 and allowing air to flow through the PFC power supply board 8 and the ballast power supply board 10. Reference numeral 18 denotes an exhaust fan, which discharges hot air that has been sent from the lamp cooling fan 14 to the lamp 1 and has cooled it, from an exhaust port 24a formed in a second side plate B24 described later.

  The lower exterior case 21 houses the lamp 1, the optical box 6, the power supply system boards 8 to 10, the control board 11, and the like. Reference numeral 22 denotes an upper outer case for covering the lower outer case 21 with the optical box 6 and the like stored therein. Reference numeral 23 denotes a first side plate, which closes a side opening formed by the outer cases 21 and 22 together with the second side plate 24. The lower exterior case 21 has the above-described intake ports 21a and 21b, and the second side plate 24 has the above-described exhaust port 24a. The lower exterior case 21, the upper exterior case 22, the first side plate 23, and the second side plate 24 constitute a housing of the projector.

  Reference numeral 25 denotes an IF board on which a connector for taking in various signals is mounted. Reference numeral 26 denotes an IF reinforcing plate attached to the inside of the first side plate 23.

  Reference numeral 27 denotes an exhaust duct for guiding the exhaust heat from the lamp 1 to the exhaust fan 18 so as not to diffuse the exhaust air into the housing. The exhaust duct 27 holds lamp exhaust louvers 19 and 20 having a light shielding function for preventing light from the lamp 1 from leaking outside the apparatus.

  Reference numeral 28 denotes a lamp lid. The lamp lid 28 is detachably disposed on the bottom surface of the lower exterior case 21 and is fixed by a screw (not shown). Reference numeral 29 denotes a set adjustment leg. The set adjustment leg 29 is fixed to the lower exterior case 21, and the height of the leg part 29a can be adjusted. The tilt angle of the projector can be adjusted by adjusting the height of the leg 29a.

  Reference numeral 30 denotes an RGB intake plate for holding a dust removal filter (not shown) attached to the outside of the intake port 21a of the lower exterior case 21.

  Reference numeral 31 denotes a prism base that holds the color separation / synthesis optical system β. Reference numeral 32 denotes a box side cover having a duct-shaped portion for guiding cooling air from the first and second optical system cooling fans 12A and 12B in order to cool the optical elements and the liquid crystal panel in the color separation / synthesis optical system β. Reference numeral 33 denotes a second RGB duct that forms a duct together with the box side cover 32.

  Reference numeral 34 denotes an RGB substrate connected to the control substrate 11 to which a flexible substrate extending from a liquid crystal panel disposed in the color separation / synthesis optical system β is connected. Reference numeral 35 denotes an RGB substrate cover for preventing electrical noise from entering the RGB substrate 34.

(Optical configuration)
Next, the configuration of the optical system including the lamp 1, the illumination optical system α, the color separation / synthesis optical system β, and the projection lens (projection optical system) 5 will be described with reference to FIG. 3A shows a horizontal section of the optical system, and FIG. 3B shows a vertical section.

  In the figure, reference numeral 41 denotes a discharge arc tube (hereinafter simply referred to as an arc tube) that emits white light in a continuous spectrum. Reference numeral 42 denotes a reflector having a concave mirror that condenses light from the arc tube 41 in a predetermined direction. The light source lamp 1 is constituted by the arc tube 41 and the reflector 42.

  Reference numeral 43a denotes a first cylinder array in which a plurality of cylindrical lens cells having refractive power in the horizontal direction shown in FIG. 43b is a second cylinder array having a plurality of cylindrical lens cells corresponding to the individual lens cells of the first cylinder array 43a. 44 is an ultraviolet absorption filter, and 45 is a polarization conversion element that converts non-polarized light into linearly polarized light having a predetermined polarization direction.

  Reference numeral 46 denotes a front compressor composed of a cylindrical lens having a refractive power in the vertical direction shown in FIG. Reference numeral 47 denotes a reflection mirror for bending the optical axis from the lamp 1 by approximately 90 degrees (more specifically, 88 degrees).

  43c is a third cylinder array in which a plurality of cylindrical lens cells having refractive power in the vertical direction are arranged. 43d is a fourth cylinder array having a plurality of cylindrical lens arrays corresponding to individual lens cells of the third cylinder array 43c.

  Reference numeral 50 denotes a color filter for returning the color in a specific wavelength region to the lamp 1 in order to adjust the color coordinates to a predetermined value. Reference numeral 48 denotes a condenser lens. Reference numeral 49 denotes a rear compressor composed of a cylindrical lens having a refractive power in the vertical direction. The illumination optical system α is configured as described above.

  58 is a dichroic mirror that reflects light in the wavelength region of blue (B: for example 430 to 495 nm) and red (R: for example 590 to 650 nm) and transmits light in the wavelength region of green (G: for example 505 to 580 nm). is there. 59 is an incident side polarizing plate for G in which a polarizing element is bonded to a transparent substrate, and transmits only P-polarized light. Reference numeral 60 denotes a first polarization beam splitter that transmits P-polarized light and reflects S-polarized light on a polarization separation surface constituted by a multilayer film.

  61R, 61G and 61B are a reflective liquid crystal panel for red, a reflective liquid crystal panel for green and a reflective liquid crystal panel for blue as image forming elements (or light modulating elements) which reflect incident light and modulate the image, respectively. is there. 62R, 62G, and 62B are a quarter wavelength plate for red, a quarter wavelength plate for green, and a quarter wavelength plate for blue, respectively.

  A trimming filter 64a returns orange light to the lamp 1 in order to increase the color purity of the R light. Reference numeral 64b denotes an incident-side polarizing plate for RB in which a polarizing element is attached to a transparent substrate and transmits only P-polarized light.

  65 is 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 66 denotes a second polarization beam splitter that transmits P-polarized light and reflects S-polarized light on the polarization separation surface.

  Reference numeral 68B denotes a B-use exit side polarizing plate (polarizing element) that rectifies only the S-polarized component of the B light. 68G is a G output-side polarizing plate that transmits only the S-polarized light component of the G light. Reference numeral 69 denotes a dichroic prism that transmits R light and B light and reflects G light.

  The above dichroic mirror 58 to dichroic prism 69 constitute a color separation / synthesis optical system β.

  In this embodiment, the polarization conversion element 45 converts P-polarized light to S-polarized light. The P-polarized light and S-polarized light described here are described with reference to the polarization direction of light in the polarization conversion element 45. On the other hand, the light incident on the dichroic mirror 58 is assumed to be P-polarized light considering the polarization directions in the first and second polarization beam splitters 60 and 66 as a reference. That is, in this embodiment, the light emitted from the polarization conversion element 45 is S-polarized light, but when the same S-polarized light is incident on the dichroic mirror 58, it is defined as P-polarized light.

(Optical action)
Next, the optical action will be described.

  Light emitted from the arc tube 41 is collected in a predetermined direction by the reflector 42. The reflector 42 has a parabolic concave mirror, and light from the focal position of the paraboloid becomes a light beam parallel to the symmetry axis of the paraboloid. However, since the light source from the arc tube 41 is not an ideal point light source and has a finite size, the condensed light flux includes many light components that are not parallel to the symmetry axis of the paraboloid. ing. These light beams are incident on the first cylinder array 43a. The light beam incident on the first cylinder array 43a is divided into a plurality of light beams corresponding to the number of cylinder lens cells and collected to form a plurality of strip-shaped light beams arranged in the vertical direction. The plurality of split light beams pass through the ultraviolet absorption filter 44 and the second cylinder array 43b to form a plurality of light source images in the vicinity of the polarization conversion element 45.

  The configuration of the polarization conversion element 45 will be described with reference to FIG. The polarization conversion element 45 includes a plurality of polarization separation surfaces 45a, a plurality of reflection surfaces 45b, and a plurality of half-wave plates 45c. The plurality of split light beams (non-polarized light) are incident on the polarization separation surface 45a corresponding to the column, and are separated into P-polarized light transmitted through the polarization separation surface 45a and S-polarized light reflected by the polarization separation surface 45a. The

  The S-polarized light reflected by the polarization separation surface 45a is reflected by the reflecting surface 45b 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 45a is converted into S-polarized light by rotating the polarization direction by 90 degrees by the half-wave plate 45c. Thus, a plurality of light beams (linearly polarized light) having the same polarization direction are emitted. To do.

  The plurality of light beams that have undergone polarization conversion are emitted from the polarization conversion element 45, compressed by the front compressor 46, reflected by the reflection mirror 47, and incident on the third cylinder array 43 c.

  The light beam incident on the third cylinder array 43c is divided into a plurality of light beams corresponding to the number of cylinder lens cells and collected to form a plurality of strip-shaped light beams arranged in the horizontal direction. The plurality of split light beams enter the rear compressor 49 via the fourth cylinder array 43d and the condenser lens 48.

  By the optical action of the front compressor 46, the condenser lens 48, and the rear compressor 49, rectangular images formed by a plurality of light beams overlap with each other to generate a rectangular uniform brightness illumination area. Reflective liquid crystal panels 61R, 61G, and 61B are disposed in this illumination area. In this way, light that illuminates the reflective liquid crystal panels 61R, 61G, 61B is generated.

  The light converted to S-polarized light by the polarization conversion element 45 enters the dichroic mirror 58. Hereinafter, the optical path of the G light transmitted through the dichroic mirror 58 will be described.

  The G light transmitted through the dichroic mirror 58 enters the incident side polarizing plate 59. Even after being decomposed by the dichroic mirror 58, the G light remains P-polarized light (S-polarized light when the polarization conversion element 45 is used as a reference). The G light exits from the incident-side polarizing plate 59, then enters the first polarizing beam splitter 60 as P-polarized light, passes through the polarization separation surface, and reaches the G reflective liquid crystal panel 61G.

  Here, an image supply device 80 such as a personal computer, a DVD player, or a TV tuner is connected to the IF board 25 of the projector. The control board 11 drives the reflective liquid crystal panels 61R, 61G, and 61B based on the image information input from the image supply device 80, and forms an original image for each color on them. Thereby, the light incident on each reflective liquid crystal panel is reflected and modulated (image modulation) according to the original image. The image supply device 80 and the projector constitute an image display system.

  In the G reflective liquid crystal panel 61G, the G light is image-modulated and reflected. The P-polarized component of the image-modulated G light is again transmitted through the polarization separation surface of the first polarization beam splitter 60, returned to the light source side, and removed from the projection light. On the other hand, the S-polarized component of the image-modulated G light is reflected by the polarization separation surface of the first polarization beam splitter 60 and travels toward the dichroic prism 69 as projection light.

  At this time, in a state where all the polarization components are converted to P-polarized light (in a state where black is displayed), a quarter-wave plate 62G provided between the first polarizing beam splitter 60 and the G-use reflective liquid crystal panel 61G. The slow axis is adjusted in a predetermined direction. Thereby, the influence of the disorder of the polarization state which generate | occur | produces with the 1st polarizing beam splitter 60 and the reflective liquid crystal panel 61G for G can be restrained small.

  The G light emitted from the first polarizing beam splitter 60 enters the dichroic prism 69 as S-polarized light, is reflected by the dichroic film surface of the dichroic prism 69, and reaches the projection lens 5.

  On the other hand, the R light and B light reflected by the dichroic mirror 58 enter the trimming filter 64a. R light and B light are still P-polarized light after being decomposed by the dichroic mirror 58. Then, after the orange light component is cut by the trimming filter 64a, the R light and the B light are transmitted through the incident side polarizing plate 64b and are incident on the color selective phase difference plate 65.

  The color-selective phase difference plate 65 has an action of rotating only the polarization direction of the R light by 90 degrees, so that the R light is incident on the second polarization beam splitter 66 as S-polarized light and the B light is incident on P-polarized light.

  The R light incident on the second polarization beam splitter 66 as S-polarized light is reflected by the polarization separation surface of the second polarization beam splitter 66 and reaches the R-use reflective liquid crystal panel 61R. The B light incident on the second polarization beam splitter 66 as P-polarized light is transmitted through the polarization separation surface of the second polarization beam splitter 66 and reaches the B-use reflective liquid crystal panel 61B.

  The R light incident on the R reflective liquid crystal panel 61R is image-modulated and reflected. The S-polarized component of the image-modulated R light is reflected again by the polarization separation surface of the second polarization beam splitter 66, returned to the light source side, and removed from the projection light. On the other hand, the P-polarized component of the image-modulated R light passes through the polarization separation surface of the second polarization beam splitter 66 and travels toward the dichroic prism 69 as projection light.

  The B light incident on the B-use reflective liquid crystal panel 61B is image-modulated and reflected. The P-polarized component of the image-modulated B light is transmitted again through the polarization separation surface of the second polarization beam splitter 66 and returned to the light source side, and is removed from the projection light. On the other hand, the S-polarized component of the image-modulated B light is reflected by the polarization separation surface of the second polarization beam splitter 66 and travels toward the dichroic prism 69 as projection light.

  At this time, by adjusting the slow axes of the quarter-wave plates 62R and 62B provided between the second polarizing beam splitter 66 and the R and B reflective liquid crystal panels 61R and 61B, As in the case, the adjustment in the black display state of each of the R and B lights can be performed.

  The R light and B light that are combined into one light beam and emitted from the second polarization beam splitter 66 are analyzed by the exit-side polarizing plate 68B and enter the dichroic prism 69. Further, the R light is transmitted through the exit-side polarizing plate 68 </ b> B as P-polarized light and enters the dichroic prism 69.

  By being analyzed by the exit-side polarizing plate 68B, the B light is ineffective generated by the B light passing through the second polarizing beam splitter 66, the B reflective liquid crystal panel 61B, and the quarter wavelength plate 62B. The light is cut from the components.

  The R light and B light incident on the dichroic prism 69 pass through the dichroic film surface and are combined with the G light reflected by the dichroic film surface to reach the projection lens 5.

  The combined R, G, B light is enlarged and projected onto a projection surface such as a screen by the projection lens 5.

  Next, a cooling structure (cooling means) for the polarization conversion element 45 in the projector according to the present embodiment will be described with reference to FIGS.

  The polarization conversion element 45 is accommodated in the optical box 6 in a state in which a light shielding and heat radiating member 70 described later is attached. A hole (not shown) is formed immediately below the polarization conversion element 45 in the optical box 6.

  As shown in FIG. 1, the cooling air to the polarization conversion element 45 is a duct (air guide path) branched from the first and second lamp ducts 15 and 16 that guides the cooling air from the lamp cooling fan 14 to the light source lamp 1. E is supplied to the polarization conversion element 45 through the hole of the optical box 6 described above. FIG. 1 shows a blowout port H formed at a position corresponding to the hole of the optical box 6 in the duct E. Cooling air from the outlet H is supplied to the polarization conversion element 45 through the hole of the optical box 6.

  The aforementioned second cylinder array 43b is disposed on the incident side of the polarization conversion element 45, and the aforementioned front compressor 46 is disposed on the exit side. The cooling air flows through the space between the second cylinder array 43 b and the polarization conversion element 45 and between the front compressor 46 and the polarization conversion element 45, and passes through a hole (not shown) formed in the optical box lid 7. It flows out of the box 6 and is discharged out of the casing.

  As shown in FIG. 1, the duct E extends from the side of the polarization conversion element 45 (the direction orthogonal to the optical path from the lamp 1 to the polarization conversion element 45) directly below the polarization conversion element 45, and is Squeezed out and blown out from the outlet H. For this reason, the cooling air blown out from the blowout port H is seen in the direction from the lower right to the upper left (specific direction) of the polarization conversion element 45 as seen from the lamp 1 side as shown by an arrow C in FIGS. It flows along the entrance surface and exit surface of the polarization conversion element 45. An arrow C also indicates a center portion of the flow of the cooling air blown out from the blowout port H.

  Compared to the flow velocity at the center C of the flow of the cooling air, the flow velocity in the region away from the center C in the direction perpendicular to the direction of the arrow C (direction D in FIG. 5) is low. . For this reason, if only the cooling air is supplied to the polarization conversion element 45, the right region of the polarization conversion element 45 as viewed from the lamp 1 side may be insufficiently cooled.

  Therefore, in this embodiment, the light shielding and radiating member 70 is provided on the incident surface of the polarization conversion element 45. The light shielding heat radiating member 70 has a light shielding function as well as a heat radiating function.

  As shown in FIG. 5, the incident surface of the polarization conversion element 45 has a transmission region (first region) B through which non-polarized light from the lamp 1 enters the polarization conversion element 45. Further, on the incident surface of the polarization conversion element 45, a non-polarized light from the lamp 1 is shielded so as not to be incident on portions other than the plurality of polarization separation surfaces indicated by 45a in the polarization conversion element 45. 2 region) A.

  The light shielding portion 70 a of the light shielding heat radiating member 70 is on the light shielding region A (on the second region) on the incident surface of the polarization conversion element 45, and on a portion other than the plurality of polarization separation surfaces 45 a inside the polarization separation element 45. It is provided so that non-polarized light does not enter. The light shielding area A is an area away from the center C of the flow of the cooling air in a direction D perpendicular to the direction of the arrow C (specific direction), and corresponds to an area where the above-described air cooling alone is insufficiently cooled. .

  In this way, the entire incident light of the polarization conversion element 45 is obtained by shielding the area A, which is insufficiently cooled only by air cooling, by the light shielding and radiating member 70 (the light shielding portion 70a) and actively radiating heat in the area. It is possible to suppress the performance deterioration due to the temperature rise due to the above.

  In addition, an extension 70 b extending from the blowout port H to the inside of the duct E is provided at the lower part of the light shielding and heat radiating member 70. By extending the extended portion 70b to the inside of the duct E where the flow velocity of the cooling air is fast, the heat radiation of the polarization conversion element 45 can be promoted.

  1 and 5 show the case where the extension portion 70b is formed in a flat plate shape, but by providing unevenness or fins on the surface of the extension portion 70b, the heat dissipation area can be expanded, and the heat dissipation effect can be further increased. Can be increased.

  Further, as the material of the light shielding and radiating member 70, high-luminance aluminum is preferable. Since the high-luminance aluminum reflects light, unnecessary light hitting the light shielding portion 70a of the light shielding heat radiating member 70 is reflected, and the temperature rise of the polarization conversion element 45 can be more effectively suppressed. Further, the heat conductivity of the high-luminance aluminum is 220 W / K · m, which is several times higher than the heat conductivity of sapphire glass, 40 W / K · m. It is easy to move to the heat dissipation part 70b. Therefore, high-luminance aluminum is suitable as a material for the light shielding and radiating member 70. High-luminance aluminum can generally be obtained at a lower cost than sapphire glass.

  Further, in the present embodiment, the light shielding heat radiating member 70 (light shielding portion 70a) is not disposed on the transmission region B in the incident surface of the polarization conversion element 45. As can be seen from FIG. 4, in the transmissive region B, there are actually effective regions in which the light from the lamp 1 is transmitted toward the polarization separation surface 45a and other unnecessary regions alternately. However, if a light-shielding heat radiating member having a plurality of light-shielding portions covering a plurality of unnecessary regions is arranged on the transmission region B, if the alignment between the polarization conversion element 45 and the light-shielding heat radiating member is not appropriate, the light enters the effective region. The light that should be blocked.

  For this reason, in this embodiment, by not providing the light shielding heat dissipation member 70 (the light shielding portion 70a) on the transmission region B, it is possible to appropriately cool the polarization conversion element 45 while avoiding such inappropriate light shielding. I am doing so.

  FIG. 6 shows a cooling structure of the polarization conversion element 45 in the liquid crystal projector that is Embodiment 2 of the present invention.

  Also on the incident surface of the polarization conversion element 45 of the present embodiment, a transmission region (first region) B that allows the non-polarized light from the lamp 1 to enter the polarization conversion element 45, and the non-polarization light to the polarization conversion element There is a light shielding region (second region) A that should be shielded so as not to be incident on the inside of 45. The light shielding region A extends from the center in the left-right direction to the left and right sides at the upper part of the incident surface.

  In this embodiment, the cooling air flows along the incident surface (and the exit surface) of the polarization conversion element 45 from directly below to above. In this case, in particular, the flow velocity in the regions on the left and right sides in the leeward (upper part of the incident surface), that is, in the region away from the central portion C of the flow of the cooling air in the direction D orthogonal to the direction of the arrow C is the center. It becomes lower than the flow velocity in part C. For this reason, the left and right regions in the upper part of the polarization conversion element 45 are likely to be undercooled.

  Therefore, in the present embodiment, as shown in FIG. 6, light shielding and heat dissipation is performed on both the left and right regions away from the central portion C of the cooling air flow in the direction D in the light shielding region A of the incident surface of the polarization conversion element 45. A plurality of light shielding portions 70 a provided on the member 70 are arranged.

  Furthermore, also in the present embodiment, an extension portion 70b extending inside the duct as the air guide path is provided at the lower portion of the light shielding and heat radiating member 70 to promote heat dissipation.

  According to the above configuration, it is possible to suppress performance deterioration due to temperature increase due to the incident light of the entire polarization conversion element 45.

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

  For example, the shape of the light shielding region A shown in each embodiment is merely an example, and may have other shapes.

  In the first embodiment, a liquid crystal projector using a reflective liquid crystal panel as an image forming element has been described. However, the present invention uses a transmissive liquid crystal panel, a digital micromirror device (DMD), or the like as an image forming element. It can also be applied to.

1 is a perspective view showing a configuration around a polarization conversion element in a liquid crystal projector that is Embodiment 1 of the present invention. FIG. 1 is an exploded perspective view illustrating an overall configuration of a liquid crystal projector of Embodiment 1. FIG. 2 is a horizontal sectional view and a vertical sectional view showing an optical configuration of the liquid crystal projector of Embodiment 1. FIG. The figure which shows the structure of the said polarization conversion element. The figure which shows the relationship between the polarization conversion element in Example 1, the light shielding heat radiating member, and the direction of the flow of cooling air. The figure which shows the relationship between the polarization conversion element in Example 2 of this invention, the light-shielding heat radiating member, and the direction of the flow of cooling air.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source lamp 6 Optical box 7 Optical box cover 14 Lamp cooling fan 15, 16 Lamp duct 45 Polarization conversion element 45a Polarization separation surface 45b Reflective surface 45c 1/2 wavelength plate 61R, 61G, 61B Reflective type liquid crystal panel 70 Light-shielding heat dissipation member 70a Light shielding part 70b Extension part A Light shielding area
B Transmission area

Claims (3)

A polarization conversion element that converts non-polarized light incident from a light source into linearly polarized light using a polarization separation surface;
An optical system that generates light that illuminates the image forming element using the linearly polarized light, and that projects the light modulated by the image forming element onto a projection surface by a projection optical system;
Cooling means for supplying cooling air to the incident surface of the polarization conversion element;
The cooling means supplies the cooling air from a specific direction along the incident surface to a first region where the non-polarized light is incident on the polarization conversion element in the incident surface,
Of the incident surface, the non-polarized light is not incident on a portion other than the polarization separation surface inside the polarization conversion element, and is separated from the center of the flow of the cooling air in a direction orthogonal to the specific direction. An image projection apparatus, wherein a heat dissipation member having a light shielding function is provided on the second region. The cooling means includes a fan and an air guide path that guides the cooling air from the fan to be supplied to the first region from the specific direction.
The image projecting device according to claim 1, wherein the heat radiating member has an extension extending inside the air guide passage. A polarization conversion element that converts non-polarized light incident from a light source into linearly polarized light;
An optical system that generates light for illuminating the image forming element using the linearly polarized light, and projects the light modulated by the image forming element onto a projection surface;
Cooling means for supplying cooling air to the incident surface of the polarization conversion element;
A heat dissipating member provided on the incident surface of the polarization conversion element,
The cooling means is
With fans,
An air guide path for guiding the cooling air from the fan to be supplied to a first region of the incident surface where the non-polarized light is incident on the polarization conversion element;
The image radiating device according to claim 1, wherein the heat dissipating member has an extension extending inside the air guide passage.