JP2009229730A - Polarization element and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarization element which is enhanced in handling properties and successfully maintains polarization separation characteristics. <P>SOLUTION: The polarization element 53 includes a first prism 531 having a luminous flux incident side end surface 531A and an emission side inclined surface 531B inclined to the luminous flux incident side end surface 531A, a second prism 532 having a luminous flux emission side end surface 532A parallel to the luminous flux incident side end surface 531A and an incident side inclined surface 532B inclined to the luminous flux emission side end surface 532A and opposed to the emission side inclined surface 531B, a polarization element body 533 provided on the incident side inclined surface 532B and a holding member 534 integrally holding respective prisms 531, 532 in a state where the emission side inclined surface 531B and the polarization element body 533 are separated at a prescribed distance. The holding member 534 is constituted of a material having a thermal conductivity equal to or lower than that of the second prism 532. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polarizing element and a projector.

Conventionally, there has been known a projector including a light source device, a light modulation element that modulates a light beam emitted from the light source device according to image information to form image light, and a projection optical device that enlarges and projects the image light. Yes.
In such projectors, polarizing elements that transmit predetermined linearly polarized light and remove other light beams from the incident light beam are usually arranged on the light beam incident side and light beam emission side of the light modulation element (liquid crystal panel). (For example, see Patent Document 1).
In the projector described in Patent Document 1, a reflection-type polarizing element is used as the exit-side polarizing element disposed on the light beam exit side of the liquid crystal panel, improving the light resistance and heat resistance of the exit-side polarizing element, and An unnecessary light flux reflected by the side polarizing element is not incident on the liquid crystal panel.
Specifically, the exit side polarization element includes a first prism having a triangular cross section having a light beam incident side end surface orthogonal to the optical axis of the incident light beam, and an exit side inclined surface inclined with respect to the light beam incident side end surface; A second prism having a triangular cross section having a light beam exit side end surface parallel to the side end surface and an incident side inclined surface that is inclined with respect to the light beam exit side end surface and faces the exit side inclined surface, and is interposed between the inclined surfaces. A reflective polarizing plate. Then, the unnecessary light beam reflected by the reflective polarizing plate is totally reflected at the light beam incident side end surface of the first prism and proceeds in a direction avoiding the liquid crystal panel.

International Publication WO01 / 055778

By the way, in consideration of handling properties when incorporating into a projector, it is preferable to integrate the first prism and the second prism as the exit side polarization element.
However, for example, when the first prism and the second prism are integrated by fixing each inclined surface with an adhesive or the like with a reflective polarizing plate interposed between the inclined surfaces, There's a problem.
That is, the reflection-type polarizing plate generally splits into two linearly polarized light beams whose polarization directions are orthogonal to each other, transmits one linearly polarized light, and reflects some of the linearly polarized light. Absorbs heat and generates heat.
Then, when the heat of the reflective polarizing plate is transmitted to the first prism and thermal distortion occurs in the first prism, it proceeds in the first prism due to the influence of the phase difference generated by the internal stress due to the thermal distortion. The polarization direction of the light beam is disturbed.
That is, the polarization direction of the light beam to be transmitted through the reflective polarizing plate is disturbed in the first prism, so that a part of the light beam is reflected by the reflective polarizing plate or the light beam to be reflected by the reflective polarizing plate. When the direction is disturbed in the first prism, there is a problem that a part of the light beam passes through the reflective polarizing plate, and the polarization separation characteristic of the exit side polarization element is deteriorated.

  An object of the present invention is to provide a polarizing element and a projector that can improve handleability and can maintain good polarization separation characteristics.

  The polarizing element of the present invention is a polarizing element that transmits predetermined linearly polarized light out of an incident light beam, and includes a light beam incident side end surface on which a light beam is incident and an exit side inclined surface that is inclined with respect to the light beam incident side end surface. A first prism having a light beam emission side end surface parallel to the light beam incident side end surface, a second prism having an incident side inclined surface that is inclined with respect to the light beam emission side end surface and faces the emission side inclined surface; The first linearly polarized light that is provided on the incident-side inclined surface and transmits the first linearly polarized light out of the light flux that has passed through the first prism and whose polarization direction is orthogonal to the first linearly polarized light is the first. A polarizing element body that reflects toward the prism, and a holding member that integrates the prisms with the exit-side inclined surface and the polarizing element body spaced apart from each other by a predetermined distance. Heat conduction of two prisms Characterized in that it is composed of a material having the following thermal conductivity.

In the present invention, the polarizing element includes a first prism, a second prism, a polarizing element body, and a holding member that integrates the prisms. Thereby, since the polarizing element is integrated by the holding member, the handling property when incorporating into the projector can be improved.
Here, the relative positional relationship of each prism, such as the parallel state of the light incident side end face of the first prism and the light exit side end face of the second prism, is important.
For example, when each prism is separately incorporated into the projector and then the relative positional relationship between the prisms is adjusted, the relative positional relationship between the prisms in a state where the optical components are densely packed. Therefore, the adjustment work becomes complicated.
On the other hand, in the present invention, since the prisms are integrated with the holding member in advance before being incorporated in the projector, the relative positions of the prisms can be easily positioned at desired positions.

The polarizing element body is provided on the incident-side inclined surface of the second prism, and the holding member integrates the prisms with the exit-side inclined surface of the first prism and the polarizing element body spaced apart by a predetermined distance. As a result, an air layer having a high heat insulating effect is interposed between the polarizing element body and the first prism. For this reason, compared with the case where a 1st prism and a polarizing element main body are joined by an adhesive etc., the heat conduction at the time of heat being transmitted from a polarizing element main body to a 1st prism can be suppressed effectively.
Further, the holding member is made of a material having a thermal conductivity equal to or lower than that of the second prism. Accordingly, it is possible to effectively suppress heat conduction via the holding member when heat is transmitted from the polarizing element body to the first prism.
Therefore, the thermal distortion of the first prism due to the influence of heat generation of the polarizing element body can be suppressed, and the polarization separation characteristics of the polarizing element can be maintained well.

In the polarizing element of the present invention, it is preferable that the prisms and the holding member are made of the same material.
In the present invention, the prisms and the holding members that are integrated with each other are made of the same material. Therefore, the linear expansion coefficients of the prisms and the holding members are the same, and the thermal expansion between the prisms and the holding members is the same. The deformation can be accommodated to the same extent. For this reason, the holding state of each prism by the holding member, that is, the relative positional relationship of each prism can be satisfactorily maintained.

A projector according to the present invention includes a light source device, a light modulation element that modulates a light beam emitted from the light source device according to image information to form image light, and a projection optical device that enlarges and projects the image light. The projector includes the polarizing element described above.
In the present invention, since the projector includes the polarizing element described above, the projector can enjoy the same operations and effects as the polarizing element described above.
In addition, since the projector includes a polarizing element that can maintain the polarization separation characteristics well, the image quality of the projected image can be maintained well.

[First embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
[Main components of the projector]
FIG. 1 is a diagram schematically showing a schematic configuration of a projector 1 in the first embodiment.
The projector 1 modulates a light beam emitted from a light source according to image information to form image light, and enlarges and projects the formed image light on a screen (not shown). As shown in FIG. 1, the projector 1 is roughly configured by an optical unit 3, a projection lens 4 as a projection optical device, and an exterior housing 2 that houses the optical unit 3 and the projection lens 4 and constitutes an exterior. ing.
Although not specifically illustrated, each of the projector 1 and the cooling unit provided with a cooling fan or the like for cooling the inside of the projector 1 in a space other than the optical unit 3 and the projection lens 4 in the exterior housing 2. It is assumed that a power supply device that supplies power to the constituent members, a control device that controls operations of the constituent members of the projector 1, and the like are arranged.

The optical unit 3 optically processes the light beam emitted from the light source device 31 under the control of the control device to form image light corresponding to the image information. This optical unit 3 has a light source device 31, an illumination optical device 32, a color separation optical device 33, a relay optical device 34, an optical device 5, and these optical components 31 to 34, 5 set therein. And an optical component casing 35 disposed at a predetermined position with respect to the illumination optical axis Ax.
As illustrated in FIG. 1, the light source device 31 includes a light source lamp 311, a reflector 312, and the like. In the light source device 31, the light beam emitted from the light source lamp 311 is aligned in the emission direction by the reflector 312, and is emitted toward the illumination optical device 32.

  As shown in FIG. 1, the illumination optical device 32 includes a first lens array 321, a second lens array 322, a polarization conversion element 323, and a superimposing lens 324. The light beam emitted from the light source device 31 is divided into a plurality of partial light beams by the first lens array 321 and forms an image in the vicinity of the second lens array 322. Each partial light beam emitted from the second lens array 322 is incident so that its central axis (principal ray) is perpendicular to the incident surface of the polarization conversion element 323, and approximately one type of linearly polarized light is generated by the polarization conversion element 323. Injected as light. A plurality of partial light beams emitted from the polarization conversion element 323 as linearly polarized light and passed through the superimposing lens 324 are superimposed on three liquid crystal panels 51 (to be described later) of the optical device 5.

As shown in FIG. 1, the color separation optical device 33 includes two dichroic mirrors 331 and 332 and a reflection mirror 333, and the dichroic mirrors 331 and 332 and the reflection mirror 333 emit the light from the illumination optical device 32. It has a function of separating a plurality of partial light beams into three color lights of red, green, and blue.
As shown in FIG. 1, the relay optical device 34 includes an incident side lens 341, a relay lens 343, and reflection mirrors 342 and 344, and color light separated by the color separation optical device 33, for example, red light, is supplied to the optical device 5. The liquid crystal panel 51R on the red light side which will be described later is guided.

The optical device 5 modulates the incident light beam according to image information to form image light.
A specific configuration of the optical device 5 will be described later.
The projection lens 4 is configured as a combined lens in which a plurality of lenses are combined, and enlarges and projects the image light emitted from the optical device 5 on the screen.

[Configuration of optical device]
FIG. 2 is an exploded perspective view schematically showing the configuration of the optical device 5.
In FIG. 2, only the G color light side is illustrated in the optical device 5, but it is assumed that the R and B color light sides have the same configuration as the G color light side.
As shown in FIG. 1 or 2, the optical device 5 includes a liquid crystal panel 51 as a light modulation element (optical element) (a liquid crystal panel on the red light side is 51R, a liquid crystal panel on the green light side is 51G, and a liquid crystal panel on the blue light side is A liquid crystal panel 51B), an incident side polarizing element 52 disposed on the front side of the optical path of each liquid crystal panel 51, an exit side polarizing element 53 disposed on the rear side of the optical path of each liquid crystal panel 51, and a color combining optical device As a cross dichroic prism 54.
In addition, below, the structure of each optical component 51-54 is demonstrated in order from the light beam entrance side.

The incident side polarization element 52 transmits only linearly polarized light having a polarization direction substantially the same as the polarization direction aligned by the polarization conversion element 323. In the present embodiment, the incident-side polarizing element 52 is configured by a reflective polarizer, like a polarizing element body 533 described later.
As shown in FIG. 2, the liquid crystal panel 51 has a configuration in which liquid crystal, which is an electro-optical material, is hermetically sealed between a pair of rectangular substrates 511 and 512 made of glass or the like. Among these, the substrate 511 is a driving substrate for driving the liquid crystal, and includes a plurality of data lines arranged in parallel to each other, a plurality of scanning lines arranged in a direction orthogonal to the plurality of data lines, The pixel electrodes are arranged in a matrix corresponding to the intersections of the scanning lines and the data lines, switching elements such as TFTs (Thin Film Transistors), and drive units that drive the switching elements. The substrate 512 is a counter substrate that is disposed to face the substrate 511 at a predetermined interval, and has a common electrode to which a predetermined voltage Vcom is applied. Further, these substrates 511 and 512 are FPCs as circuit boards that are electrically connected to the control device and output predetermined drive signals to the scanning lines, the data lines, the switching elements, the common electrodes, and the like. A cable 513 is connected. By inputting a drive signal from the control device via the FPC cable 513, a voltage is applied between the predetermined pixel electrode and the common electrode, and the alignment state of the liquid crystal interposed between the pixel electrode and the common electrode Is controlled, and the polarization direction of the polarized light beam emitted from the incident side polarization element 52 is modulated.

The exit-side polarizing element 53 transmits only the first linearly polarized light having a polarization direction orthogonal to the transmission axis of the incident-side polarizing element 52 out of the light flux emitted through the liquid crystal panel 51.
The configuration of the exit side polarization element 53 will be described later.

  The cross dichroic prism 54 combines the color lights transmitted through the exit-side polarization elements 53 to form image light (color image). The cross dichroic prism 54 has a substantially square shape in plan view in which four right angle prisms are bonded together, and two dielectric multilayer films are formed at the interface where the right angle prisms are bonded together. These dielectric multilayer films transmit G-color light emitted from the liquid crystal panel 51G and transmitted through the exit-side polarizing element 53, and R and B-color light emitted from the respective liquid crystal panels 51R and 51B and transmitted through the respective exit-side polarizing elements 53. reflect. In this way, the color lights are combined to form a color image.

[Configuration of exit-side polarizing element]
FIG. 3 is a view of the exit-side polarizing element 53 viewed from the side.
As shown in FIG. 2 or FIG. 3, the exit side polarization element 53 includes a first prism 531, a second prism 532, a polarization element body 533, and a holding member 534.
The first prism 531 is composed of a triangular prism having a right-angled triangular cross section, the light incident side end surface 531A is orthogonal to the illumination optical axis Ax, and the exit-side inclined surface 531B corresponding to the hypotenuse of the right-angled triangular cross section is the light flux. It is disposed in a state of being inclined with respect to a plane (light beam incident side end surface 531A) which is located on the exit side and orthogonal to the illumination optical axis Ax.

  The second prism 532 is a triangular prism having the same shape as the first prism 531. In the second prism 532, the light exit side end surface 532A is orthogonal to the illumination optical axis Ax, and the incident side inclined surface 532B corresponding to the hypotenuse having a right-angled triangular section is located on the light incident side and the exit side inclined surface 531B. It is arrange | positioned in the state parallel to.

FIG. 4 is a diagram showing the material, thermal conductivity, and linear expansion coefficient of the prisms 531 and 532.
The prisms 531 and 532 described above are made of the same material.
As materials of the prisms 531, 532, for example, as shown in FIG. 4, quartz, Pyrex (registered trademark), Tempax (trade name), BK7 (trade name), SK5 (trade name), SF57 ( An optical glass such as a trade name), a white plate, a blue plate, or the like can be used.

  The polarizing element body 533 is provided on the incident-side inclined surface 532B, and reflects the second linearly polarized light that transmits the first linearly polarized light and whose polarization direction is orthogonal to the first linearly polarized light. It consists of In the present embodiment, the polarizing element body 533 has a configuration in which a large number of fine linear ribs such as aluminum are formed in parallel on the incident-side inclined surface 532B, although not specifically illustrated. The polarizing element body 533 transmits linearly polarized light (first linearly polarized light) having a perpendicular polarization direction in the direction in which the linear rib extends, and linearly polarized light (secondly polarized light having a parallel polarization direction) Of linearly polarized light).

The holding member 534 is configured as a rectangular parallelepiped having a square shape in plan view, and is fixed by an adhesive so as to straddle the bottom surfaces 531D and 532D of the triangular prisms in the prisms 531 and 532, respectively. In the holding member 534, the light incident side end surface 531A and the light emitting side end surface 532A are parallel (the inclined surfaces 531B and 532B are parallel), and the emitting side inclined surface 531B and the polarizing element body 533 are separated by a predetermined distance. In this state, the prisms 531 and 532 are integrated.
In the present embodiment, as shown in FIG. 3, the holding member 534 has each bottom surface so that each side surface is parallel to the other two sides excluding the hypotenuse having a triangular cross section in each prism 531, 532. It is fixed to 531D and 532D.

In this embodiment, in order to suppress thermal distortion of the first prism 531 due to heat generated in the polarizing element body 533, the thermal conductivity and shape of the holding member 534 are set as shown below.
For example, when heat generated in the polarizing element body 533 is transmitted to the first prism 531, heat conduction through the holding member 534 can be expressed by the following formula (1).

[Equation 1]
Thermal conduction via holding member 534 (W / K) = (D × t × λ) / a (1)

Here, as shown in FIG. 3, a is a separation distance between the exit side inclined surface 531 </ b> B and the polarizing element body 533. D is a width dimension of the holding member 534, as shown in FIG. t is the thickness dimension of the holding member 534, as shown in FIG. λ is the thermal conductivity of the holding member 534.
From Equation (1), in order to suppress the thermal distortion of the first prism 531, the separation distance a between the first prism 531 and the polarizing element body 533 is large, and the width dimension D, the thickness dimension t, and the thermal dimension of the holding member 534 It is desirable that the conductivity λ is small.
The separation distance a is set to a range in which the first prism 531 and the polarizing element body 533 do not interfere with each other and do not hinder downsizing of the exit side polarizing element 53 and the optical device 5, that is, about 0.2 to 1.0 mm. ing.
Further, the width dimension D is set to be less than the vertical dimension D0 (FIG. 3) of the prisms 531 and 532 as long as the strength of the holding member 534 can be maintained.
Furthermore, the thickness dimension t is set to a range in which the strength of the holding member 534 can be maintained, that is, about 0.3 to 2.0 mm.

FIG. 5 is a diagram illustrating the material, thermal conductivity, and linear expansion coefficient of the holding member 534.
Further, the thermal conductivity λ is set to be equal to or lower than the thermal conductivity of the second prism 532.
That is, as the material of the holding member 534, for example, as shown in FIG. 5, in addition to the same material as the prisms 531 and 532, a plastic such as an acrylic resin or a vinyl chloride resin can be employed.
In the present embodiment, the holding member 534 is made of the same material as the prisms 531 and 532.

FIG. 6 is a diagram schematically showing the optical path of the light beam emitted from the exit side polarization element 53. Specifically, FIG. 6 is a longitudinal sectional view of the exit side polarization element 53.
Then, the emission side polarization element 53 emits the light beam L1 through the liquid crystal panel 51 as described below, with the above-described configuration.
That is, as shown in FIG. 6, the light beam L <b> 1 is introduced into the first prism 531, then exits from the exit-side inclined surface 531 </ b> B, and travels toward the polarizing element body 533.
The light beam L1 incident on the polarizing element body 533 is separated by the polarizing element body 533 into the first linearly polarized light L11 and the second linearly polarized light L12.
The first linearly polarized light L <b> 11 passes through the polarization element body 533, is emitted through the second prism 532, and is introduced into the cross dichroic prism 54. At this time, the first linearly polarized light L11 travels in substantially the same direction as the traveling direction of the light beam L1.
On the other hand, the second linearly polarized light L12 is reflected by the polarizing element body 533 to the light beam incident side, is introduced into the first prism 531, and then enters the light beam incident side end surface 531A. The second linearly polarized light L12 is totally reflected by the light beam incident side end surface 531A and is emitted from the end surface 531C intersecting the light beam incident side end surface 531A and the emission side inclined surface 531B of the first prism 531. That is, the second linearly polarized light L12 is emitted in a direction avoiding the liquid crystal panel 51 (upward in the present embodiment). Although not specifically shown, an antireflection film for preventing reflection of incident light and outgoing light can be formed on each end face of the first prism 531.

And each member 51-54 mentioned above is integrated as shown below.
In other words, the exit-side polarizing element 53 has the light-beam exit-side end surface 532A fixed to the light-incident-side end surface 54A (FIG. 2) of the cross dichroic prism 54 with an adhesive.
In the liquid crystal panel 51, the drive substrate 511 is fixed to the light incident side end surface 531 </ b> A of the first prism 531 with an adhesive.
Further, the incident side polarizing element 52 is fixed to the counter substrate 512 of the liquid crystal panel 51 with an adhesive.

In the present embodiment, an adhesive between the cross dichroic prism 54 and the second prism 532, an adhesive between the holding member 534 and the first prism 531 and the second prism 532, the first prism 531 and the liquid crystal panel 51 The following adhesives are employed as the adhesive between the liquid crystal panel 51 and the incident-side polarizing element 52.
That is, the adhesive preferably has a glass transition temperature of 90 ° C. or higher in order to maintain the adhesive strength in consideration of the use temperature of the liquid crystal panel 51 (for example, 60 to 80 ° C. or lower).
In addition, since the adhesive needs to be softened at a certain temperature when the reworkability is considered and each member 51 to 54 can be separated, for example, at the heat resistant temperature limit of each polarizing element 52, 53, It is preferable to have a glass transition temperature of 120 ° C. or lower that can realize a high temperature state relatively easily.
That is, the adhesive preferably has a glass transition temperature of 90 to 120 ° C.
And as a material of this adhesive, a silica type, an acrylic resin type, an epoxy resin type, a silicone type, etc. are employable. Further, as a method for curing the adhesive, an ultraviolet curing type, a two-component mixed type, a thermosetting type, an anaerobic curing type, or the like can be adopted.

The first embodiment described above has the following effects.
In the present embodiment, the exit-side polarizing element 53 includes a first prism 531, a second prism 532, a polarizing element body 533, and a holding member 534 that integrates the prisms 531 and 532. As a result, the exit-side polarizing element 53 is integrated by the holding member 534, so that the handleability when incorporated in the projector 1 can be improved.
Further, since the prisms 531 and 532 are integrated in advance by the holding member 534 before being incorporated into the projector 1, the relative positions of the prisms 531 and 532 can be easily positioned at desired positions.

In addition, the polarizing element body 533 is provided on the incident-side inclined surface 532B of the second prism 532, and the holding member 534 is in a state where the emission-side inclined surface 531B of the first prism 531 and the polarizing element body 533 are separated by a predetermined distance. The prisms 531 and 532 are integrated. As a result, an air layer having a high heat insulation effect is interposed between the polarizing element body 533 and the first prism 531. For this reason, compared with the case where the 1st prism 531 and the polarizing element main body 533 are joined by an adhesive etc., the heat conduction at the time of heat being transferred from the polarizing element main body 533 to the first prism 531 is effectively suppressed. it can.
Further, the holding member 534 is made of a material having a thermal conductivity equal to or lower than that of the second prism 532. Thus, heat conduction via the holding member 534 when heat is transmitted from the polarizing element body 533 to the first prism 531 can be effectively suppressed.
Therefore, the thermal distortion of the first prism 531 due to the influence of heat generation of the polarizing element body 533 can be suppressed, and the polarization separation characteristic of the exit side polarizing element 53 can be maintained well.
In addition, since the polarization separation characteristic of the exit side polarization element 53 can be maintained satisfactorily, the image quality of the projection image projected from the projector 1 can be maintained satisfactorily.

  In addition, since the prisms 531 and 532 and the holding member 534 that are integrated with each other are made of the same material, the linear expansion coefficients of the prisms 531 and 532 and the holding member 534 are the same. Thermal expansion deformation between 532 and the holding member 534 can be accommodated to the same extent. Therefore, the holding state of the prisms 531 and 532 by the holding member 534, that is, the relative positional relationship between the prisms 531 and 532 can be maintained well.

  Further, the exit side polarization element 53 is configured such that the light beam incident side end surface 531A and the light beam exit side end surface 532A are parallel to each other. Thereby, the traveling directions of the incident light beam L1 to the exit side polarization element 53 and the first linearly polarized light L11 transmitted through the exit side polarization element 53 can be set substantially the same. Therefore, the optical system can be easily used when used in combination with the liquid crystal panel 51 disposed in the upstream of the optical path of the exit side polarizing element 53 or the cross dichroic prism 54 disposed in the downstream of the optical path of the exit side polarizing element 53. In other words, the optical components 51 and 54 can also be integrated to form the optical device 5, so that the handleability can be further improved.

  Further, since the liquid crystal panel 51, the exit-side polarizing element 53, and the cross dichroic prism 54 that are fixed to each other can be made of materials having substantially the same linear expansion coefficient as shown in FIG. The thermal expansion deformation between them can be accommodated in substantially the same extent. Therefore, the thermal stress generated due to the difference in the linear expansion coefficient can be relieved, the mutual displacement of the liquid crystal panels 51R, 51G, 51B can be prevented, and the pixel displacement can be avoided.

  Further, in the liquid crystal panel 51, the first prism 531 is fixed to the drive substrate 511, and the incident side polarization element 52 is fixed to the counter substrate 512, so that dust adheres to the light incident side and the light output side. However, it is not necessary to attach dust-proof glass for shifting the dust from the focus position and preventing the dust from being displayed as a shadow in the projected image, and the configuration of the optical device 5 can be simplified and miniaturized.

[Second Embodiment]
Next, 2nd Embodiment of this invention is described based on drawing.
In the following description, the same structure and the same members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted or simplified.
FIG. 7 is a perspective view schematically showing the configuration of the exit-side polarizing element 53 in the second embodiment.
In the present embodiment, as shown in FIG. 7, the exit side polarization element 53 is obstructed in addition to the first prism 531, the second prism 532, the polarization element body 533, and the holding member 534 as compared to the first embodiment. The only difference is that the member 535 is provided. Other configurations are the same as those in the first embodiment.

The closing member 535 is made of a material having a low thermal conductivity (for example, paper) and is formed in a sheet shape. The blocking member 535 is disposed across the entire outer edge of each of the inclined surfaces 531B and 532B across the prisms 531 and 532 in a state where the prisms 531 and 532 are integrated by the holding member 534. It is fixed to each prism 531 532 with an adhesive or the like.
As described above, the closing member 535 is fixed to each of the prisms 531 and 532, so that the holding member 534 and the closing member 535 form a sealed space between the exit-side inclined surface 531B and the polarizing element body 533.

According to the second embodiment described above, there are the following effects in addition to the same effects as in the first embodiment.
In the present embodiment, the exit-side polarizing element 53 includes a closing member 535 that forms a sealed space between the exit-side inclined surface 531B and the polarizing element body 533. Thus, the blocking member 535 can prevent the air flow between the exit-side inclined surface 531B and the polarizing element body 533. For this reason, heat transfer via convection of the air layer when heat is transferred from the polarizing element body 533 to the first prism 531 can be more effectively suppressed.
In addition, since the blocking member 535 can prevent dust and the like from entering the sealed space, the dust and the like can be prevented from adhering to the polarizing element body 533.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
In each of the embodiments described above, the holding member 534 is configured as a rectangular parallelepiped in plan view, but is not limited thereto, and may be formed in other rectangular parallelepiped shapes, cylindrical shapes, triangular prism shapes, or rod shapes. .
In each of the above embodiments, the holding member 534 is fixed so as to straddle the bottom surfaces 531D and 532D of the prisms 531 and 532. However, as long as the prisms 531 and 532 can be integrated, they can be provided at other positions. I do not care.

In each of the above embodiments, the prisms 531 and 532 are integrated by the holding member 534 to configure the exit-side polarizing element 53, and the optical components 51 to 54 are integrated to configure the optical device 5. Not limited to this, as long as at least the prisms 531 and 532 are integrated by the holding member 534, the other optical components 51, 52, and 54 are not integrated with the exit-side polarizing element 53. It does not matter. Further, between the liquid crystal panel 51 and the incident side polarizing element 52 and the exit side polarizing element 53, other optical elements such as a retardation plate, a viewing angle compensator (a WV film (Fuji Photo Film Co., Ltd. on a translucent substrate), Or the like) may be present. Further, another optical element such as a phase difference plate or a polarizing plate may exist between the exit-side polarizing element 53 and the cross dichroic prism 54. In these cases, all the optical elements or a part thereof may be integrated.
In each said embodiment, when fixing said other optical element and each members 51-53 using an adhesive agent, although the adhesive agent which has a glass transition temperature of 90-120 degreeC is used, glass transition temperature is used. However, an adhesive having a temperature of 120 ° C. or higher may be used.
Moreover, in each said embodiment, when integrating each member 51-54, although the adhesive agent was used, you may integrate by other means, such as not only this but a double-sided tape.

In each of the above embodiments, the first prism 531 and the second prism 532 may have different shapes. Further, the first prism 531 and the second prism 532 may be made of different materials.
For example, the shape of the end face 531C of the first prism 531 may be formed so that the second linearly polarized light L12 totally reflected by the light incident side end face 531A is incident orthogonally.
In each of the above-described embodiments, the emission-side inclined surface 531B is positioned on the light-beam emission side so that the second linearly polarized light L12 is emitted upward, and is on a plane (light-beam-incidence-side end surface 531A) orthogonal to the illumination optical axis Ax. However, the present invention is not limited to this, and as long as the liquid crystal panel 51 is avoided, the emission side inclined surface 531B may be inclined in any direction, up, down, left, or right.

In each of the above embodiments, the configuration of the polarizing element body 533 is not limited to the configuration described in each of the above embodiments, and any configuration may be used as long as it is a reflective polarizer.
For example, as the polarizing element body 533, a polymer-type layered polarization in which an organic material having refractive index anisotropy (birefringence) such as a polarization separation element formed of a dielectric multilayer film or a liquid crystal material is laminated in layers. A plate, an optical element that combines a quarter-wave plate with a circularly polarizing reflector that separates unpolarized light into clockwise circularly polarized light and counterclockwise circularly polarized light, and reflects and transmits polarized light using Brewster's angle You may employ | adopt the optical element isolate | separated into polarized light, or the hologram optical element using a hologram.

In each of the embodiments described above, the configuration of the polarizing element according to the present invention is employed for the exit-side polarizing element 53. However, the present invention is not limited to this, and may be employed for the incident-side polarizing element 52.
In the second embodiment, the closing member 535 is not limited to the configuration fixed to the prisms 531 and 532 as long as it is configured to have a sealed space between the exit-side inclined surface 531B and the polarizing element body 533. You may form in the box shape which accommodates the whole output side polarizing element 53 demonstrated in 1st Embodiment inside.
In each of the embodiments described above, the configuration of the polarizing element body 533 is not limited to the configuration in which the reflective polarizer is formed on the surface of the second prism 532, and the reflective polarizer is formed on a 0.3 to 2.0 mm flat plate. A structure in which the formed prism is bonded to the second prism 532 may be used.
For example, the polarizing element main body 533 may be obtained by cutting a wafer having a thickness of 1 mm on which a large number of fine linear ribs such as aluminum are formed in parallel into a predetermined size. In this case, the polarizing element body 533 which is a flat plate formed with a reflective polarizer is bonded to the second prism 532 after manufacturing.

In each of the embodiments described above, the example of the three-plate projector 1 provided with three liquid crystal panels 51 has been described. However, the present invention is not limited to this, and the configuration in which only one liquid crystal panel 51 is provided, and two liquid crystal panels 51 are provided. The configuration may be a configuration in which four or more liquid crystal panels 51 are provided.
In each of the embodiments, only the example of the front projection type projector has been described. However, the present invention is also applicable to a rear type projector that includes a screen and performs projection from the back side of the screen.

  The present invention can be used for a polarizing element of a projector used for a presentation or a home theater because it can improve the handleability and can maintain a good polarization separation characteristic.

FIG. 2 is a diagram schematically illustrating a schematic configuration of a projector according to the first embodiment. The disassembled perspective view which shows the structure of the optical apparatus in the said embodiment typically. The figure which looked at the exit side polarization element in the embodiment from the side. The figure which shows the material of each prism in the said embodiment, thermal conductivity, and a linear expansion coefficient. The figure which shows the material of the holding member in the said embodiment, thermal conductivity, and a linear expansion coefficient. The figure which shows typically the optical path of the light beam inject | emitted from the output side polarizing element in the said embodiment. The perspective view which shows typically the structure of the output side polarizing element in 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Projector, 4 ... Projection lens (projection optical apparatus), 31 ... Light source device, 51 ... Liquid crystal panel (light modulation element), 53 ... Emission side polarization element, 531 ... First prism, 531A ... light beam incident side end surface, 531B ... emission side inclined surface, 532 ... second prism, 532A ... light beam emission side end surface, 532B ... incident side inclined surface, 533. ... Polarizing element body, 534... Holding member, L1... Incident light beam, L11... First linearly polarized light, L12.

Claims (3)

A polarizing element that transmits predetermined linearly polarized light in the incident light beam,
A first prism having a light beam incident side end surface on which a light beam is incident, and an exit side inclined surface inclined with respect to the light beam incident side end surface;
A second prism having a light beam emission side end surface parallel to the light beam incident side end surface, and an incident side inclined surface that is inclined with respect to the light beam emission side end surface and faces the emission side inclined surface;
The second linearly polarized light, which is provided on the incident-side inclined surface and transmits the first linearly polarized light out of the light flux passing through the first prism and whose polarization direction is orthogonal to the first linearly polarized light, is A polarizing element body reflecting toward one prism;
A holding member that integrates the prisms in a state where the exit-side inclined surface and the polarizing element body are spaced apart from each other by a predetermined distance;
The said holding member is comprised with the material which has the heat conductivity below the heat conductivity of a said 2nd prism. The polarizing element characterized by the above-mentioned. The polarizing element according to claim 1,
Each of the prisms and the holding member are made of the same material. A polarizing element. A projector comprising: a light source device; a light modulation element that modulates a light beam emitted from the light source device according to image information to form image light; and a projection optical device that magnifies and projects the image light,
A projector comprising the polarizing element according to claim 1.

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