JP2010210984A - Optical element and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element capable of suppressing reduction in the performance of the optical element caused due to a high-temperature use environment, and capable of suppressing reduction in the performance of the optical element caused due to deformation of a polarizing plate, compared with a conventional optical element; and to provide a projector of high quality in which deterioration in a projection image is reduced. <P>SOLUTION: The optical element 1 includes a polarizing plate 10, a first translucent substrate 20 stuck to the polarizing plate 10 with a first adhesive 14, and a second translucent substrate 30 stuck to the polarizing plate 10 with a second adhesive 16, wherein both of the first translucent substrate 20 and the second translucent substrate 30 are composed of an inorganic material, and any Young's modulus of the first adhesive 14 and the second adhesive 16 is 20 MPa or more in a temperature range of 80 to 110°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical element and a projector.

  Conventionally, comprising a polarizing plate made of a polarizing layer, a first translucent substrate bonded to one surface of the polarizing plate, and a second translucent substrate bonded to the other surface of the polarizing plate, An optical element in which both a first light-transmitting substrate and a second light-transmitting substrate are made of an inorganic material is known (for example, see Patent Document 1). In a conventional optical element, for example, a flexible pressure-sensitive adhesive is used in order to bond a light-transmitting substrate to a polarizing plate.

  For this reason, according to the conventional optical element, instead of using the TAC film to support the polarizing plate, the transparent substrate made of an inorganic material is used to support the polarizing plate. It is possible to suppress the performance degradation of the optical element due to the above.

  Further, according to the conventional optical element, since a flexible adhesive is used to bond the translucent substrate to the polarizing plate, the polarizing plate (for example, a polarizing plate made of PVA) is used in a high-temperature usage environment. It is possible to relieve internal stress generated between each translucent substrate and the polarizing plate due to the initial thermal shrinkage, and as a result, each translucent substrate and polarizing plate It becomes possible to suppress peeling and tearing of the polarizing plate.

JP 2007-256898 A

  However, in the conventional optical element, since a flexible adhesive is used to bond the translucent substrate to the polarizing plate, the polarizing plate is deformed relatively greatly in a high temperature use environment. . As a result, there is a problem that the performance of the optical element due to the deformation of the polarizing plate is lowered, which may be an obstacle when trying to further improve the image quality.

  Therefore, the present invention has been made to solve the above-described problems, and can suppress a decrease in performance of the optical element due to a high-temperature use environment, and the optical element due to deformation of the polarizing plate. An object of the present invention is to provide an optical element capable of suppressing the performance degradation of the conventional device. It is another object of the present invention to provide a high-quality projector that includes such an optical element and causes little deterioration of a projected image.

  The optical element of the present invention includes a polarizing plate comprising a polarizing layer, a first translucent substrate bonded to one surface of the polarizing plate by a first adhesive, and the polarizing plate by a second adhesive. A second light-transmitting substrate bonded to the other surface of the first light-transmitting substrate and the second light-transmitting substrate, both of which are optical elements made of an inorganic material, The Young's modulus of each of the first adhesive and the second adhesive is 20 MPa or more in a temperature range of 80 ° C. to 110 ° C.

  For this reason, according to the optical element of the present invention, since the polarizing plate is supported by using the light-transmitting substrate made of an inorganic material, it is possible to suppress the performance degradation of the optical element due to the high temperature use environment. It becomes possible.

  In addition, according to the optical element of the present invention, the Young's modulus of each of the first adhesive and the second adhesive is 20 MPa or more in the temperature range of 80 ° C. to 110 ° C., and thus is shown in a test example described later. As described above, the polarizing plate is not greatly deformed, and as a result, it is possible to suppress the performance degradation of the optical element due to the deformation of the polarizing plate as compared with the conventional case.

  In the optical element of the present invention, it is preferable that the first adhesive and the second adhesive have a glass transition point of 110 ° C. or higher.

  By adopting such a configuration, it becomes possible to have a stable Young's modulus and strength in a temperature range of 80 ° C. to 110 ° C., so that the polarizing plate can be held more stably in a high temperature use environment. .

  In the optical element of the present invention, the polarizing plate has a physical pretreatment for improving the affinity between the polarizing plate and at least one of the first adhesive and the second adhesive. It is preferable that the polarizing plate is made.

  By setting it as such a structure, it becomes possible to suppress peeling with a polarizing plate and an adhesive agent.

  In the optical element of the present invention, the polarizing plate has a chemical pretreatment for improving the affinity between the polarizing plate and at least one of the first adhesive and the second adhesive. It is preferable that the polarizing plate is made.

  Also with such a configuration, it is possible to suppress peeling between the polarizing plate and the adhesive.

  In the optical element of the present invention, it is preferable that at least one of the first light-transmitting substrate and the second light-transmitting substrate is a light-transmitting substrate made of sapphire or quartz.

  By adopting such a structure, the light-transmitting substrate made of these materials has excellent thermal conductivity, so that the heat generated in the polarizing plate can be efficiently dissipated, and the temperature of the polarizing plate rises. Can be effectively suppressed.

  In the optical element of the present invention, at least one of the first translucent substrate and the second translucent substrate is made of quartz glass, hard glass, crystallized glass, or a cubic sintered body. A light substrate is preferred.

  With such a configuration, the light-transmitting substrate made of these materials has low birefringence, so that it is possible to suppress deterioration in the quality of the light beam passing through the light-transmitting substrate, and the light beam incident on the polarizing plate. Or it becomes possible to suppress the quality fall of the light beam inject | emitted from a polarizing plate. In addition, since the light-transmitting substrate made of these materials has a low coefficient of thermal expansion, the polarizing plate is supported by the light-transmitting substrate made of such a material having a low coefficient of thermal expansion, thereby suppressing deformation of the polarizing plate. It becomes possible.

  In the optical element of the present invention, the first adhesive and the second adhesive are preferably ultraviolet curable adhesives.

  The ultraviolet curable adhesive has a feature that it can be cured at an arbitrary timing by irradiating ultraviolet rays after application. For this reason, the use of such an adhesive makes it easy to manufacture the optical element.

  The projector of the present invention includes an illumination device that emits light, a liquid crystal device that modulates light emitted from the illumination device according to image information, a projection optical system that projects light modulated by the liquid crystal device, A projector comprising: an optical element disposed on at least one of a light incident side and a light emission side of the liquid crystal device, wherein the optical element is the above-described optical element of the present invention.

  For this reason, since the projector of the present invention includes the optical element whose performance is not easily lowered as described above, it becomes a high-quality projector with little deterioration of the projected image.

FIG. 3 is a view for explaining the optical element 1 according to the first embodiment. FIG. 3 is a schematic diagram for explaining physical pretreatment for the polarizing plate 10 of the optical element 1 according to the first embodiment. FIG. 6 is a diagram illustrating an optical system of a projector 1000 according to a second embodiment. FIG. 6 is a diagram for explaining a main part of a projector 1000 according to a second embodiment. The figure shown in order to demonstrate the optical element 1a which concerns on a test example. The figure shown in order to demonstrate the optical element 1a which concerns on a test example.

  Hereinafter, an optical element and a projector according to the present invention will be described based on the embodiments shown in the drawings. In the first embodiment, the optical element of the present invention will be described, and in the second embodiment, the projector of the present invention will be described.

[Embodiment 1]
FIG. 1 is a diagram for explaining an optical element 1 according to the first embodiment. FIG. 1A is a schematic view of the optical element 1 viewed from the first light-transmissive substrate 20 side, and FIG. 1B is a cross-sectional view taken along line A ₁ -A _{1 in} FIG. In FIG. 1, the respective thicknesses of the polarizing plate 10, the first adhesive 14, and the second adhesive 16 are exaggerated.

  As shown in FIG. 1, the optical element 1 according to Embodiment 1 includes a polarizing plate 10, a first light-transmitting substrate 20 bonded to one surface of the polarizing plate 10 with a first adhesive 14, It is an optical element provided with the 2nd translucent board | substrate 30 bonded together on the other surface in the polarizing plate 10 with the 2nd adhesive agent 16. FIG.

  As shown in FIG. 1, the polarizing plate 10 is a polarizing plate made of a polarizing layer. As the polarizing layer, for example, PVA is dehydrated to form a double bond, or PVA is dyed with iodine or a dichroic dye, and then the uniaxially stretched, the double bond molecule, or the dye A polarizing layer base material formed so that the molecules are aligned in one direction is subjected to a physical pretreatment described later, and then cut into an appropriate size. The polarizing layer thus subjected to the uniaxial stretching process has a function of absorbing polarized light in a direction parallel to the uniaxial stretching direction and transmitting polarized light in a direction perpendicular to the uniaxial stretching direction.

  The polarizing plate 10 is a polarizing plate that has been subjected to physical pretreatment for improving the affinity between the polarizing plate 10 and the first adhesive 14 and the second adhesive 16. The physical pretreatment is, for example, a corona treatment performed on the polarizing layer base material. The corona treatment is a treatment for generating a corona discharge between a target substance and an electrode. Various radicals and ions are generated by corona discharge and react with surrounding molecules to introduce functional groups such as carbonyl groups on the surface of the target substance. As a result, the property of the surface of the target substance is changed.

  FIG. 2 is a schematic diagram for explaining the physical pretreatment for the polarizing plate 10 of the optical element 1 according to the first embodiment.

  The corona treatment is performed by, for example, a corona treatment device 60. As shown in FIG. 2, the corona treatment device 60 includes feed rolls 62 and 64, a treatment roll 66, an electrode unit 68, and a power supply device 70.

The feed rolls 62 and 64 feed the polarizing layer base material 18 at a constant speed in a predetermined direction.
The processing roll 66 feeds the polarizing layer substrate 18 fed from the feed roll 62 toward the feed roll 64. The processing roll 66 is grounded as shown in FIG.
As shown in FIG. 2, the electrode portion 68 has a distal end portion that is movable in the vicinity of the processing roll 66. A high voltage is applied to the electrode portion 68 via the power supply device 70, and as a result, corona discharge occurs between the tip portion of the electrode portion 68 and the polarizing layer base material 18 on the processing roll 66.
As shown in FIG. 2, the power supply device 70 includes an oscillator 72 and a high-voltage transformer 74, and applies a high voltage to the electrode unit 68.

The corona treatment as described above is performed on both the one surface and the other surface of the polarizing layer substrate 18, and the affinity with each of the first adhesive 14 and the second adhesive 16. To improve.
The polarizing layer base material 18 that has been subjected to the corona treatment is then cut into an appropriate size and used as the polarizing layer 12 in the polarizing plate 10.

The first translucent substrate 20 and the second translucent substrate 30 are translucent substrates made of an inorganic material, for example, sapphire. A translucent substrate made of sapphire has a high thermal conductivity of about 40 W / (m · K), a very high hardness, a low coefficient of thermal expansion, and is hardly scratched and has high transparency. In the case where importance is attached to low cost as a medium luminance, the first light-transmitting substrate 20 and the second light-transmitting substrate 30 are quartz crystals having a thermal conductivity of approximately 10 W / (m · K). A translucent substrate made of may be used. From the viewpoint of thermal conductivity, the thickness of the first light-transmitting substrate 20 and the second light-transmitting substrate 30 is preferably 0.2 mm or more. From the viewpoint of reducing the thickness of the optical element and reducing the cost. Therefore, it is preferably 2.0 mm or less.
Note that both the first light-transmitting substrate 20 and the second light-transmitting substrate 30 have a predetermined optical axis.

  As shown in FIG. 1, the polarizing plate 10 and the first translucent substrate 20 are bonded together with a first adhesive 14. Moreover, the polarizing plate 10 and the 2nd translucent board | substrate 30 are bonded together through the 2nd adhesive agent 16, as shown in FIG. The Young's modulus of each of the first adhesive 14 and the second adhesive 16 is 20 MPa or more in the temperature range of 80 ° C to 110 ° C. Each of the first adhesive 14 and the second adhesive 16 is an ultraviolet curable adhesive having a glass transition point of 110 ° C. or higher.

  Note that the first adhesive 14 and the second adhesive 16 may be the same type of adhesive or different types of adhesives as long as the above-described conditions are satisfied.

  An antireflection layer (not shown) is formed on the surface of the first light transmitting substrate 20 opposite to the polarizing plate 10 and the surface of the second light transmitting substrate 30 opposite to the polarizing plate 10. .

  As described above, the optical element 1 according to Embodiment 1 is an optical element in which the Young's modulus of each of the first adhesive 14 and the second adhesive 16 is 20 MPa or more in the temperature range of 80 ° C. to 110 ° C. is there.

  As described above, according to the optical element 1 according to the first embodiment, the polarizing plate 10 is supported by using a light-transmitting substrate made of an inorganic material. It becomes possible to suppress the performance degradation of the element 1.

  Moreover, according to the optical element 1 which concerns on Embodiment 1, since the Young's modulus of any of the 1st adhesive agent 14 and the 2nd adhesive agent 16 is 20 Mpa or more in the temperature range of 80 to 110 degreeC, it mentions later. As shown in the test example, the polarizing plate 10 is not greatly deformed, and as a result, the performance degradation of the optical element 1 due to the deformation of the polarizing plate 10 can be suppressed as compared with the conventional example.

  Moreover, according to the optical element 1 which concerns on Embodiment 1, the 1st adhesive agent 14 and the 2nd adhesive agent 16 have a glass transition point of 110 degreeC or more, and were stable in the temperature range of 80 to 110 degreeC. Since it has Young's modulus and strength, the polarizing plate 10 can be held more stably in a high-temperature use environment.

  Further, according to the optical element 1 according to the first embodiment, the polarizing plate 10 is a polarizing plate that has been subjected to physical pretreatment for improving the affinity between the polarizing plate 10 and the adhesive. It is possible to suppress peeling between the adhesive and the adhesive.

  Moreover, according to the optical element 1 which concerns on Embodiment 1, since the 1st translucent board | substrate 20 and the 2nd translucent board | substrate 30 are the translucent board | substrates which consist of sapphire, they are very heat conductive. The heat generated in the polarizing plate 10 can be efficiently dissipated, and the temperature increase of the polarizing plate 10 can be effectively suppressed.

  Further, according to the optical element 1 according to the first embodiment, the first adhesive 14 and the second adhesive 16 are ultraviolet curable adhesives, and the ultraviolet curable adhesive emits ultraviolet rays after application. It is characterized by being able to be cured at an arbitrary timing by irradiation. For this reason, the use of such an adhesive makes it easy to manufacture the optical element.

[Embodiment 2]
FIG. 3 is a diagram illustrating an optical system of the projector 1000 according to the second embodiment.
FIG. 4 is a diagram for explaining a main part of the projector 1000 according to the second embodiment. 4A is a view of the peripheral portion of the cross dichroic prism 500 as viewed from above, and FIG. 4B is a peripheral portion of the incident-side optical element 420R in the A ₂ -A ₂ cross section of FIG. 4A. FIG. 4C is a diagram showing a peripheral portion of the emission side optical element 450R in the A ₂ -A ₂ cross section of FIG. In FIGS. 3 and 4, the thicknesses of the components in each optical element are exaggerated.

  As shown in FIG. 3, the projector 1000 according to the second embodiment includes an illumination device 100, a color separation light guide optical system 200, liquid crystal devices 410 </ b> R, 410 </ b> G, and 410 </ b> B, a cross dichroic prism 500, and a projection optical system 600. It is a projector provided with. Each of these optical systems is housed in a housing 700.

  As shown in FIG. 3, the illumination device 100 includes a light source device 110, a first lens array 120, a second lens array 130, a polarization conversion element 140, and a superimposing lens 150, and emits light.

  The light source device 110 includes an arc tube 112, an ellipsoidal reflector 114, a secondary mirror 116, and a concave lens 118. The light source device 110 is a light source that emits light substantially parallel to the illuminated region, and emits light having the illumination optical axis 100ax as a central axis.

  The arc tube 112 has a tube portion and a pair of sealing portions extending on both sides of the tube portion, and has a light emission center in the vicinity of the first focal point of the ellipsoidal reflector 114. The tube portion is made of quartz glass formed in a spherical shape, and includes a pair of electrodes disposed in the tube portion, mercury, a rare gas, and a small amount of halogen sealed in the tube portion. As the arc tube 112, various arc tubes can be employed, for example, a metal halide lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, or the like.

  The ellipsoidal reflector 114 includes a cylindrical neck that is inserted and fixed to one sealing portion of the arc tube 112, and a reflective concave surface that reflects the light emitted from the arc tube 112 toward the second focal position. Have

  The secondary mirror 116 is a reflecting means that covers substantially half of the bulb portion of the arc tube 112 and is arranged to face the reflective concave surface of the elliptical reflector 114. The sub mirror 116 is inserted and fixed to the other sealing portion of the arc tube 112. The secondary mirror 116 returns the light emitted from the arc tube 112 that does not go to the ellipsoidal reflector 114 to the arctube reflector 114 and makes it incident on the ellipsoidal reflector 114.

  The concave lens 118 is disposed on the illuminated area side of the ellipsoidal reflector 114. And it is comprised so that the condensing light from the ellipsoidal reflector 114 may be inject | emitted as the substantially parallel light toward the 1st lens array 120. FIG.

  The first lens array 120 has a function as a beam splitting optical element that splits light from the light source device 110 into a plurality of partial beams, and the plurality of first small lenses 122 are in a plane orthogonal to the illumination optical axis 100ax. It has a configuration arranged in a matrix of multiple rows and multiple columns. Although not illustrated, the outer shape of the first small lens 122 is similar to the outer shape of the image forming area of the liquid crystal devices 410R, 410G, and 410B.

  The second lens array 130 has a function of forming the image of each first small lens 122 of the first lens array 120 in the vicinity of the image forming area of the liquid crystal devices 410R, 410G, and 410B together with the superimposing lens 150. The second lens array 130 has substantially the same configuration as the first lens array 120, and a plurality of second small lenses 132 are arranged in a matrix of a plurality of rows and a plurality of columns in a plane orthogonal to the illumination optical axis 100ax. Have a configuration.

The polarization conversion element 140 is a polarization conversion element that emits the polarization direction of each partial light beam divided by the first lens array 120 as approximately one type of linearly polarized light having a uniform polarization direction.
The polarization conversion element 140 transmits one linearly polarized light component among the polarized light components included in the illumination light beam from the light source device 110 and reflects the other linearly polarized light component in a direction perpendicular to the illumination optical axis 100ax, and A reflection layer that reflects the other linearly polarized light component reflected by the polarization separation layer in a direction parallel to the illumination optical axis 100ax, and a phase difference that converts the other linearly polarized light component reflected by the reflective layer into one linearly polarized light component. And a board.

  The superimposing lens 150 collects a plurality of partial light beams that have passed through the first lens array 120, the second lens array 130, and the polarization conversion element 140, and superimposes them in the vicinity of the image forming area in the liquid crystal devices 410R, 410G, and 410B. It is an element. The superimposing lens 150 is arranged so that the optical axis of the superimposing lens 150 and the illumination optical axis 100ax of the illumination device 100 substantially coincide. In addition, although the superimposing lens 150 shown in FIG. 3 is comprised with one lens, you may be comprised with the compound lens which combined several lenses.

  The color separation light guide optical system 200 includes dichroic mirrors 210 and 220, reflection mirrors 230, 240 and 250, an incident side lens 260, and a relay lens 270. The color separation light guide optical system 200 separates the light emitted from the illumination device 100 into three color lights of red light, green light, and blue light, and the respective color lights are liquid crystal devices 410R, 410G, 410B to be illuminated. Has the function of leading to

  The dichroic mirrors 210 and 220 are optical elements on which a wavelength selection film that reflects a light beam in a predetermined wavelength region and transmits a light beam in another wavelength region is formed on a substrate. The dichroic mirror 210 disposed in the front stage of the optical path is a mirror that reflects a red light component and transmits other color light components. The dichroic mirror 220 disposed in the latter stage of the optical path is a mirror that transmits the blue light component and reflects the green light component.

  The red light component reflected by the dichroic mirror 210 is bent by the reflection mirror 230 and enters the image forming area of the liquid crystal device 410R for red light through the condenser lens 300R.

  The condenser lens 300R is provided to convert each partial light beam from the superimposing lens 150 into light substantially parallel to each principal ray. The condenser lens 300R is held by a heat conductive holding member (not shown), and is disposed in the housing 700 via the heat conductive holding member. The other condensing lenses 300G and 300B are configured similarly to the condensing lens 300R.

  Of the green light component and the blue light component that have passed through the dichroic mirror 210, the green light component is reflected by the dichroic mirror 220, passes through the condenser lens 300G, and enters the image forming area of the green light liquid crystal device 410G. On the other hand, the blue light component is transmitted through the dichroic mirror 220, passes through the incident side lens 260, the incident side reflection mirror 240, the relay lens 270, the emission side reflection mirror 250, and the condensing lens 300B, and is a liquid crystal for blue light. The light enters the image forming area of the apparatus 410B. The incident side lens 260, the relay lens 270, and the reflection mirrors 240 and 250 have a function of guiding the blue light component transmitted through the dichroic mirror 220 to the liquid crystal device 410B.

  The reason that the incident side lens 260, the relay lens 270, and the reflection mirrors 240 and 250 are provided in the optical path of blue light is that the length of the optical path of blue light is longer than the length of the optical paths of other color lights. For this reason, a decrease in light use efficiency due to light divergence or the like is prevented. The projector 1000 according to the second embodiment has such a configuration because the optical path length of blue light is long, but the length of the optical path of red light is increased so that the incident side lens 260 and the relay lens 270 are formed. And the structure which uses the reflective mirrors 240 and 250 for the optical path of red light is also considered.

The liquid crystal devices 410R, 410G, and 410B modulate each color light according to image information, and are illumination targets of the illumination device 100.
Each of the liquid crystal devices 410R, 410G, and 410B is obtained by encapsulating a liquid crystal that is an electro-optical material in a pair of transparent glass substrates. For example, incident-side polarization is performed according to a given image signal using a polysilicon TFT as a switching element. Modulates the polarization direction of one kind of linearly polarized light emitted from the elements 420R, 420G, and 420B. Although not shown, the liquid crystal devices 410R, 410G, and 410B are held by a liquid crystal device holding frame made of, for example, an aluminum die-cast frame.

As shown in FIG. 4, the incident-side optical elements 420R, 420G, and 420B are disposed between the condenser lenses 300R, 300G, and 300B and the liquid crystal devices 410R, 410G, and 410B, and from the condenser lenses 300R, 300G, and 300B. Of the emitted light, it has a function of transmitting only linearly polarized light having an axis in a predetermined direction and absorbing other light.
The incident side optical element 420R has the same configuration as the optical element 1 according to the first embodiment shown in FIG. Further, the incident side optical element 420R is attached to the casing 700 by a heat conducting member 720 as shown in FIG. Although detailed illustration is omitted, the incident side optical elements 420G and 420B have the same configuration as the incident side optical element 420R.

The emission-side optical elements 450R, 450G, and 450B are disposed between the liquid crystal devices 410R, 410G, and 410B and the cross dichroic prism 500, and the light is emitted from the liquid crystal devices 410R, 410G, and 410B in the predetermined direction. It has a function of transmitting only linearly polarized light having light and absorbing other light.
The emission side optical element 450R has the same configuration as the optical element 1 according to Embodiment 1 shown in FIG. Further, as shown in FIG. 4C, the emission side optical element 450R is attached to the housing 700 by a heat conducting member 722. Although detailed illustration is omitted, the exit side optical elements 450G and 450B have the same configuration as the exit side optical element 450R.

  These incident side polarizing elements 420R, 420G, 420B and exit side polarizing elements 450R, 450G, 450B are set and arranged so that the directions of the polarization axes thereof are orthogonal to each other.

The cross dichroic prism 500 is an optical element that forms a color image by synthesizing an optical image modulated for each color light emitted from each of the exit-side polarizing elements 450R, 450G, and 450B. As shown in FIG. 3, the cross dichroic prism 500 has three light incident end faces that respectively receive the color lights modulated by the liquid crystal devices 410R, 410G, and 410B, and a light emission end face that emits the combined color lights. ing. The cross dichroic prism 500 has a substantially square shape in plan view in which four right-angle prisms are bonded together, and a dielectric multilayer film is formed on a substantially X-shaped interface in which the right-angle prisms are bonded together. The dielectric multilayer film formed at one of the substantially X-shaped interfaces reflects red light, and the dielectric multilayer film formed at the other interface reflects blue light. By these dielectric multilayer films, the red light and the blue light are bent and aligned with the traveling direction of the green light, so that the three color lights are synthesized.
As shown in FIG. 4B, the cross dichroic prism 500 is disposed in the housing 700 via a heat conductive spacer 710.

  The color image emitted from the cross dichroic prism 500 is enlarged and projected by the projection optical system 600 to form a screen image on the screen SCR.

Although not shown here, the projector 1000 is provided with at least one fan and a plurality of cooling air flow paths for cooling each optical system and the like. Air taken in from the outside of the projector 1000 circulates in the projector 1000 by these fans and a plurality of cooling air flow paths, and is discharged to the outside. The air flowing from the ventilation holes (cooling air flow paths) provided in the housing 700 promotes heat radiation from the cross dichroic prism 500 and the like.
Thereby, the heat of each optical system of the projector 1000 can be efficiently removed.

  As described above, the projector 1000 according to the second embodiment includes the illumination device 110, the liquid crystal devices 410R, 410G, and 410B, the projection optical system 600, and the incident light disposed on the light incident side of the liquid crystal devices 410R, 410G, and 410B. The projector includes the side optical elements 420R, 420G, and 420B and the emission side optical elements 450R, 450G, and 450B arranged on the light emission side, and the incident side optical elements 420R, 420G, and 420B and the emission side optical elements 450R, 450G, and 450B has the same configuration as the optical element according to the first embodiment.

  Therefore, the projector 1000 according to the second embodiment includes the incident-side optical elements 420R, 420G, and 420B and the emission-side optical elements 450R, 450G, and 450B that have the same configuration as the optical element 1 according to the first embodiment. Therefore, the projector is provided with an optical element whose performance is not easily lowered, and a high-quality projector with little deterioration of a projected image.

[Test example]
This test example is a test example for clarifying by simulation that the optical element of the present invention is an optical element capable of suppressing the performance degradation of the optical element due to a high temperature use environment.

FIG. 5 is a diagram for explaining the optical element 1a according to the test example. FIG. 5A is a schematic view of the optical element 1a before the polarizing plate 10a is thermally contracted, as viewed from the first light-transmissive substrate 20a side, and FIG. 5B is A _{3 in} FIG. -A is a cross-sectional view of ₃ and FIG. 5 (c) is a partially enlarged cross-sectional view in which the range of R in FIG. 5 (b) is enlarged and displayed.
FIG. 6 is a diagram for explaining the optical element 1a according to the test example. FIG. 6A is a schematic view of the optical element 1a after the polarizing plate 10a is thermally contracted as viewed from the first light-transmissive substrate 20a side, and FIG. 6B is A _{3 in} FIG. 6A. -A is a cross-sectional view of _{3 and} FIG. 6C is a partially enlarged cross-sectional view that displays an enlarged range of R in FIG. 6B.
In FIGS. 5 and 6, the thickness and the degree of thermal shrinkage of the polarizing plate 10a, the first adhesive 14a, and the second adhesive 16a are exaggerated and displayed.

  The optical element 1a according to the test example has basically the same structure as the optical element 1 according to the first embodiment. That is, as shown in FIG. 5 and FIG. 6, the optical element 1a according to the test example is bonded to one surface of the polarizing plate 10a by the polarizing plate 10a made of a polarizing layer and the first adhesive 14a. The light transmissive substrate 20a and the second light transmissive substrate 30a bonded to the other surface of the polarizing plate 10a by the second adhesive 16a.

FIG. 5 shows a state before the polarizing plate 10a of the optical element 1a according to the test example is thermally contracted. In the state before the polarizing plate 10a is thermally contracted, as shown in FIG. 5, the end portion of the layer of the first adhesive 14a that bonds the polarizing plate 10a and the first light-transmitting substrate 20a is It is configured to be perpendicular to one translucent substrate 20a. In FIG. 5 _(c), display the sides of the end of the first adhesive 14a in the A 3 -A ₃ section as _{S 1.} In the state before the polarizing plate 10a is thermally contracted, the length of _{S 1} is equal to the thickness _{L 0} of the first adhesive 14a.

The second adhesive 16a is the same as that of the first adhesive 14a, in FIG. 5 _(c), the display of the sides of the end of the second adhesive 16a in the A 3 -A ₃ section as _{S 2} To do. In the test example, it is assumed that the thickness of the second adhesive 16a is equal to the thickness of the first adhesive 14a. Therefore, in a state before the polarizing plate 10a is thermally contracted, the length of _{S 2} is equal to _{L 0.}

FIG. 6 shows a state after the polarizing plate 10a of the optical element 1a according to the test example is thermally contracted. At this time, the polarizing plate 10a is often thermally contracted to have a shape as shown in FIG. That is, the four corners of the polarizing plate 10a are not easily moved by heat shrinkage because they are firmly supported by the adhesive. Moreover, although the polarizing plate 10a is uniaxially stretched in the manufacturing process, the direction in which the direction shrinks when heat shrinks is large. The A ₃ -A ₃ cross-sectional view shown in FIG. 6B shows a place where the thermal contraction of the polarizing plate 10a is the largest in the optical element 1a.

  The stress generated when the polarizing plate 10a is about to contract by heat can be obtained from the Young's modulus of the polarizing plate and the rate of thermal contraction. The Young's modulus is a physical property value indicating the ease of expansion and contraction of a certain substance. The Young's modulus is E, the deformation ratio (the ratio at which a certain substance is expanded and contracted with respect to the entire length, the same applies hereinafter) is ε, and the stress is If σ, it can be expressed as E = σ / ε. In other words, the greater the Young's modulus, the less likely a material will stretch or shrink. Here, since the unit of stress is Pa, the unit of Young's modulus is also Pa. Note that the Young's modulus varies depending on the temperature even in the same material, but here, the Young's modulus in a temperature range of 80 ° C. to 110 ° C. will be discussed.

In the case of a general PVA as a material of the polarizing plate 10a, the Young's modulus is about 10 × 10 ⁹ Pa, and about 10 GPa when expressed using a prefix. Moreover, PVA heat-shrinks about 0.1% with respect to a full length in 90-100 degreeC. In this case, the stress generated when the polarizing plate 10a is about to shrink by heat can be obtained from the equation representing the Young's modulus in the relationship of σ = E · ε. That is, (10 × 10 ⁹ ) × (0.001) = 10 × 10 ⁶ , and as can be seen from this, about 10 × 10 ⁶ Pa, a stress of about 10 MPa occurs when expressed using a prefix. become.

When the polarizing plate 10a is thermally contracted, as shown in FIG. 6, _{S 1} and _{S 2} extends pulled polarizer 10a. As described above, the Young's modulus is a physical property value that indicates the ease of expansion and contraction of a certain substance. Therefore, the polarizing plate 10a is actually used by the Young's modulus of the first adhesive 14a and the second adhesive 16a. How much heat shrinks. In this test example, it is assumed that the Young's modulus of the first adhesive 14a and the second adhesive 16a are equal for the sake of explanation.

Here, the thickness of the 1st adhesive agent 14a and the 2nd adhesive agent 16a is 10 micrometers-30 micrometers, for example. The polarizing plate 10a is, for example, a rectangle having a side of 10 mm to 30 mm. If the thermal contraction of the polarizing plate 10a is approximately the same as the thickness of the adhesive, it can be said that the influence of the thermal contraction is sufficiently small. It is possible to suppress the degradation of the performance of the optical element due to this. In the following, the thermal shrinkage of the polarizing plate 10a is considered to be the same as the thickness L ₀ of the adhesive.

In the state after the polarizer 10a is thermally contracted, as shown in FIG. 6 (c), the S ₁ and the length of the S ₂ after extending the L _1. The length of L ₁ is determined from twice the square root of _{L 0, L 1} is about 1.5 times the length of _{L 0.} That is, deformation rate of the side portions S ₁ and S ₂ between before and after heat shrinkage, it comes to about 50%.

The Young's modulus satisfying this condition can be obtained from the above-described equation E = σ / ε. That is, (10 × 10 ⁶ ) / (0.5) = 20 × 10 ⁶ , and in order to sufficiently suppress the thermal contraction of the polarizing plate 10a, the Young's modulus of the adhesive supporting the polarizing plate 10a is 20 MPa. That is all you need to do. Actually, since the polarizing plate 10a is supported by both the first adhesive 14a and the second adhesive 16a, if the Young's modulus of both adhesives is 20 MPa or more, the safety is doubled or more. It is possible to take a rate.

  In addition, the thickness of the polarizing plate 10a is, for example, about 20 μm to 50 μm. Therefore, since the polarizing plate 10a is thin enough, it can be said that all the generated internal stress is applied to the adhesive.

In addition, the larger the Young's modulus of the adhesive, the more the thermal contraction of the polarizing plate 10a can be suppressed. However, from the viewpoint of this test example, there is an upper limit to the value at which the effect can be expected. That is, when the Young's modulus of the first adhesive 14a and a second adhesive 16a is 10 GPa, since the Young's modulus of the adhesive and the polarizing plate of the Young's modulus is equal, than the elongation of S ₁ and S ₂ The ease of shrinkage of the adhesive surface is a problem. For this reason, the Young's modulus required for the first adhesive 14a and the second adhesive 16a is 10 GPa or less.

In addition, since each thermal expansion of the 1st translucent board | substrate 20a and the 2nd translucent board | substrate 30a is sufficiently small compared with the thermal contraction of the polarizing plate 10a, there is no influence in said test example. It was supposed to be.
Further, the thermal expansion of the first adhesive 14a and the second adhesive 16a is smaller than that of the polarizing plate 10a, and further expands so as to suppress the thermal contraction of the polarizing plate 10a. In this test example, there was no effect.

  The optical element and the projector of the present invention have been described based on the above embodiment, but the present invention is not limited to the above embodiment. The present invention can be carried out in various modes without departing from the gist thereof, and for example, the following modifications are possible.

(1) In each of the above embodiments, a light-transmitting substrate made of sapphire is used as the first light-transmitting substrate or the second light-transmitting substrate, but the present invention is not limited to this. As the first light-transmitting substrate or the second light-transmitting substrate, in addition to the light-transmitting substrate made of sapphire, the light-transmitting material made of quartz, quartz glass, hard glass, crystallized glass, or cubic sintered body A conductive substrate may be used. When a light-transmitting substrate made of quartz is used as the first light-transmitting substrate or the second light-transmitting substrate, the same effect as in the case of a light-transmitting substrate made of sapphire can be obtained. In addition, when a light-transmitting substrate made of quartz glass, hard glass, crystallized glass, or a cubic sintered body is used as the first party light-transmitting substrate or the second light-transmitting substrate, these materials are used. Since the translucent board | substrate which consists of has small birefringence, the quality degradation of the light which passes a translucent board | substrate can be suppressed. In addition, since a light-transmitting substrate made of these materials has a relatively small coefficient of thermal expansion, a polarizing plate having a property of being largely deformed by heat is bonded to the light-transmitting substrate made of such a material having a small coefficient of thermal expansion. Thereby, deformation of the polarizing plate can be suppressed. When a translucent substrate made of crystallized glass is used as the first translucent substrate or the second translucent substrate, the axial direction in which the thermal expansion of the crystallized glass is large and the stretching direction of the polarizing plate are aligned. Thus, deformation of the polarizing plate due to heat can be suppressed. Moreover, as a 1st translucent board | substrate or a 2nd translucent board | substrate, the translucent board | substrate which consists of other transparent glass (For example, white plate glass, Pyrex (trademark), etc.), the translucent board | substrate which consists of YAG polycrystal A light-transmitting substrate, a translucent substrate made of aluminum oxynitride, or the like can also be preferably used. In other words, the first light-transmitting substrate or the second light-transmitting substrate may be a light-transmitting substrate made of an inorganic material.

(2) In each of the above-described embodiments, the case where a light-transmitting substrate made of the same material is used as the first light-transmitting substrate and the second light-transmitting substrate has been described as an example. It is not limited to. For example, as one of the first light-transmitting substrate and the second light-transmitting substrate, a light-transmitting substrate made of quartz glass, hard glass, crystallized glass, or a cubic sintered body is used. Alternatively, a translucent substrate made of sapphire or quartz may be used as the other optical element.

(3) In each of the above embodiments, as the first adhesive and the second adhesive, the adhesive having a glass transition point of 110 ° C. or more is used, but the present invention is limited to this. It is not a thing. Even if a glass transition point is 110 degrees C or less, what is necessary is just an adhesive agent which has a Young's modulus of 20 Mpa or more in the temperature range of 80 to 110 degreeC.

(4) In each of the above embodiments, as the first adhesive and the second adhesive, an adhesive having a Young's modulus of 20 MPa or more is used, but the first adhesive or the second adhesive is used. As the agent, an adhesive having a double Young's modulus of 40 MPa or more and the other as a pressure-sensitive adhesive may be used. In this case, a double Young's modulus is required for holding on one side, but the manufacturing method is easier on both sides than in the case of an adhesive.

(5) In each of the above embodiments, the corona treatment is performed on both the one surface and the other surface of the polarizing layer substrate 18, and each of the first adhesive 14 and the second adhesive 16 is performed. However, the present invention is not limited to this. For example, the corona treatment may be performed only on one surface of the polarizing layer base material to improve the affinity with one of the first adhesive and the second adhesive. Moreover, it is good also as not performing a corona treatment.

(6) In each of the embodiments described above, the physical pretreatment is exemplified by the case of the corona treatment, but the present invention is not limited to this. For example, plasma treatment, ozone treatment, Itro (registered trademark) treatment, or the like can be used.

(7) In each of the embodiments described above, the polarizing plate 10 is a polarizing plate that has been subjected to physical pretreatment for improving the affinity between the polarizing plate 10 and the adhesive. It is not limited. For example, the polarizing plate may be a polarizing plate subjected to a chemical pretreatment for improving the affinity between the polarizing plate and the adhesive. Also with such a configuration, it is possible to suppress peeling between the polarizing plate and the adhesive. Examples of the chemical pretreatment include application of a silane coupling agent.

(8) In each of the above embodiments, the ultraviolet curable adhesive is used as the first adhesive 14 and the second adhesive 16, but the present invention is not limited to this. For example, a visible light curable adhesive may be used.

(9) In each of the above embodiments, the adhesive is not covering the end of the polarizing plate, but the present invention is not limited to this. For example, an adhesive may cover the end of the polarizing plate.

(10) In the second embodiment, the projector using the three liquid crystal devices 410R, 410G, and 410B is described as an example. However, the present invention is not limited to this. For example, the present invention can be applied to a projector using one, two, or four or more liquid crystal devices.

(11) In the second embodiment, as the light source device, the light source device 110 including the ellipsoidal reflector 114, the arc tube 112 having the emission center near the first focal point of the ellipsoidal reflector 114, and the concave lens 118 is used. However, the present invention is not limited to this. For example, a light source device having a parabolic reflector and an arc tube having a light emission center near the focal point of the parabolic reflector can be used.

(12) In the second embodiment, the secondary mirror 116 is used as the reflecting means disposed in the arc tube 112, but the present invention is not limited to this. It is also preferable to use a reflective film as the reflecting means. In the projector 1000 according to the second embodiment, the arc tube 112 is provided with the secondary mirror 116, but the present invention is not limited to this. For example, the secondary mirror may not be provided.

(13) In the second embodiment, the lens integrator optical system including the lens array is used. However, the present invention is not limited to this. For example, a rod integrator optical system made of a rod member can be used.

(14) The present invention is applied to a rear projection projector that projects from a side opposite to the side that observes the projected image, even when applied to a front projection projector that projects from the side that observes the projected image. Is also possible.

DESCRIPTION OF SYMBOLS 1, 1a ... Optical element 10, 10a ... Polarizing plate 14, 14a ... 1st adhesive agent, 16, 16a ... 2nd adhesive agent, 18 ... Polarizing layer base material, 20, 20a ... 1st light transmission Substrate 30, 30 a... Second translucent substrate, 60. Corona treatment device, 62, 64... Feed roll, 66 .. treatment roll, 68 .. electrode portion, 70. Transformer, 100 ... illumination device, 100ax ... illumination optical axis, 110 ... light source device, 112 ... arc tube, 114 ... ellipsoidal reflector, 116 ... secondary mirror, 118 ... concave lens, 120 ... first lens array, 122 ... first small Lens 130... Second lens array 132. Second small lens 140. Polarization conversion element 150. Superimposing lens 200 Color separation light guide optical system 210 and 220 Dichroic mirror 230, 240 and 250 Reflection mirror, 260 ... incident side lens, 270 ... relay lens, 300R, 300G, 300B ... condensing lens, 410R, 410G, 410B ... liquid crystal device, 420R, 420G, 420B ... incident side optical element, 450R, 450G, 450B ... exit side optical element, 500 ... cross dichroic prism 600 ... projection optical system, 700 ... housing, 710 ... heat conductivity of the spacer, 720, 722 ... heat conduction member, 1000 ... projector, L 0 _... first adhesive , L ₁ ... the lengths of S ₁ and S ₂ after stretching, S ₁ ... the end part of the first adhesive, S ₂ ... the end part of the second adhesive, SCR ... the screen

Claims (8)

A polarizing plate comprising a polarizing layer;
A first light-transmitting substrate bonded to one surface of the polarizing plate by a first adhesive;
A second translucent substrate bonded to the other surface of the polarizing plate by a second adhesive;
The first translucent substrate and the second translucent substrate are both optical elements made of an inorganic material,
An optical element characterized in that the Young's modulus of each of the first adhesive and the second adhesive is 20 MPa or more in a temperature range of 80 ° C to 110 ° C. The optical element according to claim 1,
The optical element, wherein the first adhesive and the second adhesive have a glass transition point of 110 ° C. or higher. The optical element according to claim 1 or 2,
The polarizing plate is a polarizing plate subjected to physical pretreatment for improving the affinity between the polarizing plate and at least one of the first adhesive and the second adhesive. A featured optical element. The optical element according to claim 1 or 2,
The polarizing plate is a polarizing plate that has been subjected to a chemical pretreatment for improving the affinity between the polarizing plate and at least one of the first adhesive and the second adhesive. A featured optical element. In the optical element in any one of Claims 1-4,
An optical element, wherein at least one of the first light-transmitting substrate and the second light-transmitting substrate is a light-transmitting substrate made of sapphire or quartz. In the optical element in any one of Claims 1-4,
At least one of the first translucent substrate and the second translucent substrate is a translucent substrate made of quartz glass, hard glass, crystallized glass, or a cubic sintered body. An optical element. In the optical element in any one of Claims 1-6,
The optical element, wherein the first adhesive and the second adhesive are ultraviolet curable adhesives. A lighting device that emits light;
A liquid crystal device that modulates light emitted from the illumination device according to image information;
A projection optical system that projects light modulated by the liquid crystal device;
A projector including an optical element disposed on at least one of a light incident side and a light emission side of the liquid crystal device,
The projector according to claim 1, wherein the optical element is an optical element according to claim 1.

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