JP2018004849A - Cooling mechanism of liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To meet the need for the durable lift of a polarization conversion element due to the increased luminance of a projector, with the organic film material of a retardation film and the adhesive of a polarization element mentioned as the causes of degradation of durability, and although an inorganic crystal is adopted for the retardation film as a substitute for the organic film and a heat resistant adhesive is selected for the adhesive of the polarization element, they are not constructed so as to fully satisfy durability, giving rise to the need for a highly efficient cooling mechanism for the polarization conversion element.SOLUTION: An air guiding shape is provided for sending a cooling air to a retardation film-less area on the emission surface side of a polarization conversion element where a retardation film is arranged, making it possible to cool the retardation film while reducing a temperature difference between the incidence side and emission side of the polarization element. Therefore, since the degradation of the retardation film and the adhesive of the polarization element can reduced, it possible to improve the durable life of the polarization conversion element.SELECTED DRAWING: Figure 4

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 constituted 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). Further, 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.

  In recent years, projectors are in the trend of miniaturization and high brightness, the intensity of light per unit area of the polarization conversion element is increased, and the polarization conversion element is required to have excellent light resistance and heat resistance.

  Although the retardation film of the change conversion element uses an organic polycarbonate film, its heat resistance and light resistance are weak, and it is difficult to satisfy the performance with respect to the light intensity and temperature required for the polarization conversion element. .

  As a countermeasure against this, an inorganic quartz crystal is adopted for the retardation plate from an organic polycarbonate.

  Quartz phase plate is expensive compared to polycarbonate phase difference plate, so the light intensity is strong and the temperature of the optical axis is high. A proposal has been made to adopt a polycarbonate phase plate (Patent Document 1).

  In addition, in consideration of the direction of the cooling air, a proposal has been made to arrange a polycarbonate phase plate in a region on the windward side where the cooling effect is high, and a quartz phase plate in a region on the leeward side (Patent Document 2).

JP 2006-284648 A JP 2010-85948 A

  However, with the increase in luminance, demands for heat resistance and light resistance of the polarization conversion element are required not only for the phase plate but also for the adhesive that fixes the polarization element.

  In conventional cooling of the polarization conversion element, the air flow path of the cooling air or the selection of the material of the retardation film is selected after taking into account the temperature distribution of the retardation film. However, performance degradation due to heat resistance and light resistance of the adhesive sometimes becomes a problem.

In order to solve the above-described problem, a cooling mechanism for a liquid crystal projector according to the present invention includes:
A light source that emits light; a polarization conversion element that converts non-polarized light incident from the light source into linearly polarized light using a polarization separation surface; 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 by a projection optical system; and a cooling unit that supplies cooling air to the polarization conversion element. A first strip-like shape in which a beam splitter for reflecting the second polarized light orthogonal to the first polarized light and the second polarized light is added to the irradiated non-polarized light and the first polarized light as a predetermined polarization component is added. Polarized light is reflected by the beam splitter, and a second strip shape in which a reflecting film to be further reflected is disposed is disposed on the polarizing element portions alternately arranged at predetermined intervals and the light irradiated from the light source. The polarizing element disposed on the output side The cooling means is arranged along a region where the retardation plate is not disposed on the exit surface side of the polarizing element where the retardation plate is disposed. And having a wind guide shape for supplying cooling air.

  According to the cooling mechanism of the liquid crystal projector according to the present invention, a wind guide shape for sending cooling air to the region where the phase difference plate is not arranged is provided on the exit surface side where the phase difference plate of the polarization conversion element is arranged. Thus, the phase difference plate can be cooled while reducing the temperature difference between the incident side and the exit side of the polarizing element. For this reason, since deterioration of the adhesive agent between the retardation plate and the polarizing element can be reduced, the durability life of the polarizing conversion element can be improved.

1 is a perspective view showing the overall configuration of a liquid crystal projector in an embodiment of the present invention. Horizontal sectional view and vertical sectional view showing an optical configuration of a liquid crystal projector in an embodiment of the present invention The figure which shows the structure of the polarization conversion element of the liquid crystal projector in the Example of this invention. The perspective view which shows the cooling structure of the polarization conversion element in the Example of this invention The front view which shows the cooling structure of the polarization conversion element in the Example of this invention

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

(Overall configuration of projector)
FIG. 1 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 that guides the wind from both 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.

  2A shows a horizontal section of the optical system, and FIG. 2B 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 polarization element composed of a plurality of reflection surfaces 45b, and a plurality of half-wave plates (phase difference 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 polarizing elements described above are bonded together in a strip shape, and the above-described polarization separation surface 45a and a plurality of reflecting surface 45b portions are bonded and fixed.

  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 disturbance 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 64 a, the R light and the B light are transmitted through the incident-side polarizing plate 64 b 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.

  Cooling air to the polarization conversion element 45 is supplied to the polarization conversion element 45 from a hole of the optical box 6 through a duct (air guide path) through cooling air from a polarization conversion element cooling fan (not shown). Cooling air passes through the hole 6b of the optical box 6 corresponding to the outlet of the duct and is supplied to the polarization conversion element 45.

  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 housing.

  As shown in FIG. 4, the cooling air is blown out toward the polarization conversion element 45 from the rear side of the phase difference plate 45 c of the polarization conversion element 45.

  In this embodiment, an air guide shape 70a is provided on the phase difference plate holding frame 70 that holds the phase difference plate 45c of the polarization conversion element 45, and the cooling air is guided to a phase where the phase difference plate 45c is not disposed. It is configured.

  The air guide plate 70a is arranged at intervals where the phase difference plate 45c is not arranged at a predetermined interval, and the region where the phase difference plate 45c is not arranged due to the air guide shape 70a is disposed in the phase difference plate 45c. The air is guided parallel to the longitudinal direction (cooling air A).

  In the region where the air guide shape 70a is not disposed, the cooling air B is guided to the incident side where the second cylinder array 43b is disposed, and the incident surface side of the polarization conversion element 45 is cooled.

  By actively sending cooling air to the region where the phase difference plate 45c is not arranged by the air guide shape 70a as in this embodiment, the cooling efficiency of the polarizing element is reduced without impairing the cooling efficiency corresponding to the thickness of the phase difference plate 45c. Since cooling air can be sent to the front and back surfaces, deterioration of the adhesive of the polarizing element can be reduced.

1 light source lamp, 6 optical box, 7 optical box lid, 14 lamp cooling fan,
15, 16 Lamp duct, 45 Polarization conversion element, 45a Polarization separation surface,
45b reflective surface, 45c half-wave plate, 61R, 61G, 61R reflective liquid crystal panel,
70 retardation plate holding frame, 70a light shielding part, 70b light transmitting part, A exit side cooling air,
B Incident side cooling air

Claims (3)

A light source that emits light; a polarization conversion element that converts non-polarized light incident from the light source into linearly polarized light using a polarization separation surface; 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 by a projection optical system; and a cooling unit that supplies cooling air to the polarization conversion element.
The polarization conversion element is formed with a beam splitter that adds non-polarized light emitted from the light source to the first polarized light, which is a predetermined polarization component, and reflects second polarized light orthogonal to the first polarized light. A polarizing element portion in which a first strip shape and a second strip shape in which a second polarizing light is reflected by the beam splitter and a reflecting film to be further reflected are arranged alternately at a predetermined interval; It is arranged on the output side with respect to the light irradiated from the light source, and is composed of a phase difference plate that aligns the polarization direction of the output light from the polarizing element,
The cooling means has an air guide shape for supplying cooling air along a region where the phase difference plate is disposed and on an exit surface side of the polarizing element where the phase difference plate is disposed. LCD projector cooling mechanism. 2. The cooling mechanism for a liquid crystal projector according to claim 1, wherein the retardation plate is positioned and held on a retardation plate holding frame, and the air guide shape is provided on the retardation plate holding frame. The cooling means is configured such that cooling air is blown from the exit surface side to the polarization conversion element, and the air guide shape of the retardation plate holding frame is provided along a phase where the retardation plate is not disposed. The cooling mechanism for a liquid crystal projector according to claim 1, wherein the cooling mechanism is a liquid crystal projector.