JP2007058018A - Projection type display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarization converting element having heat resistance and durability in consideration of distribution of temperature given to the polarization conversion element. <P>SOLUTION: The polarization conversion element is constituted by disposing a polarizing film which transmits first polarized light of a predetermined polarizing direction among incident light from a light source and reflects second polarized light of a polarizing direction perpendicular to the predetermined polarizing direction and a reflecting film which reflects the second polarized light reflected by the polarizing film inside a transparent member. Further a plurality of polarization converting sections in which a retardation plate is provided are closely disposed in parallel to each other at any one side among a light emitting side of the first polarized light of the transparent member and a light emitting side of the second polarized light thereof. In this polarization converting element 5, the retardation plate made of quartz crystal is used as the retardation plate 53a located at a place near a central part of an optical axis and the retardation plate made of a resin is used as the retardation plate 53b at other place. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a projection display device using an illumination optical system that combines an integrator optical system and a polarization conversion optical system.

  2. Description of the Related Art Conventionally, as a device for displaying a large screen image, there is known a projection image display device that irradiates a liquid crystal panel with the powerful light of an illumination device and enlarges and projects an image displayed on the liquid crystal panel on a screen. Yes. A liquid crystal panel is an element that displays an image by modulating light in a certain polarization direction of incident light in combination with a polarizing plate. In general, since light emitted from the illumination device includes various polarization components, the light is converted to a single polarized light using a polarization conversion element and then irradiated onto the liquid crystal panel.

  FIG. 1 is a schematic diagram showing a basic configuration of a projection display device using a general illumination optical system. In the figure, white light emitted from the light source unit 1 is emitted as parallel light by a parabolic reflector 2, passes through a UV-IR cut filter (not shown) that removes infrared and ultraviolet components, The light beam is split by a so-called integrator optical system composed of first and second fly-eye lenses 3 and 4 formed of a plurality of rectangular convex lens groups. Each light beam converges and enters the polarization conversion element 5, and is emitted with the polarization directions aligned.

  Then, after the light whose polarization directions are aligned passes through the condenser lens 6 and the like, the blue band light is transmitted by the dichroic mirror 7 and the light in the red to green band is reflected.

  The blue band light transmitted through the dichroic mirror 7 has its optical path changed by 90 degrees by the total reflection mirror 8 and is incident on the liquid crystal display element 9 for displaying the blue band light component image, where it is optically modulated according to the input signal. Although not shown, the liquid crystal display element is provided with an incident side polarizing plate and an outgoing side polarizing plate.

  The light-modulated light enters the dichroic prism 10, the optical path is changed by 90 degrees in the dichroic prism 10, enters the projection lens 11, is enlarged, and is imaged on a screen (not shown).

  On the other hand, red to green band light reflected by the dichroic mirror 7 and whose optical path is changed by 90 degrees is incident on the dichroic mirror 12. Since the dichroic mirror 12 has a characteristic of reflecting the green band light, the green band light is reflected here, the optical path thereof is changed by 90 degrees, and the light enters the liquid crystal display element 13, and here according to the input signal Light modulated. The light-modulated green band light enters the dichroic prism 10 and the projection lens 11 in this order, and is enlarged and projected to form an image on the screen.

  The red band light transmitted through the dichroic mirror 12 is incident on the liquid crystal display element 14 via a lens (not shown) and total reflection mirrors 16 and 17, where it is optically modulated according to an input signal. The light-modulated red band light is incident on the dichroic prism 10, the optical path is changed by 90 degrees by the dichroic prism 10, incident on the projection lens 11, magnified and projected, and imaged on the screen.

  As described above, the polarization conversion element 5 is used to efficiently generate one type of polarized light from a light source that generates random polarized light. The configuration of the polarization conversion element 5 will be described with reference to FIG.

  FIG. 2 is an enlarged schematic view showing a part of the first fly-eye lens 3, the second fly-eye lens 4 and the polarization conversion element 5 of FIG.

  The polarization conversion element 5 includes a polarizing film 51 that forms an angle of 45 ° with respect to the optical axis of the optical system, a reflective film 52, a transparent member 50 that sandwiches the polarizing film and the reflective film, and a retardation plate. 53... For example, glass is used as the transparent member. A transparent member such as a glass plate having a polarizing film on the front surface and a reflective film on the back surface is disposed in close contact with each other at an angle of 45 degrees, and a predetermined emission surface and an incident surface are in contact with the polarizing film and the reflection film. A transparent member 50 shown in FIG. 3 is formed by cutting out to have an angle of 45 degrees. The phase difference plate 53 is attached to the emission side surface of the transparent member 50 on the polarizing film 51.

  In this example, a retardation plate 53 is affixed, and a polarization conversion unit 60 is composed of a transparent member portion sandwiching the polarizing film 51 and a transparent member portion sandwiching the adjacent reflection film 52. The pitch (x) between the polarizing film 51 and the reflective film 52 provided alternately is slightly larger than approximately ½ of the width (W) of the lens cell 4 a of the second fly-eye lens 4. Since the reflection film 52 only needs to reflect incident light, a polarizing film may be provided and only its reflection function may be used.

  Next, the operation of the polarization conversion element 5 will be described. The light L emitted from the light source passes through the first fly-eye lens 3 and the second fly-eye lens 4 and enters the polarizing film 51 of the corresponding polarization converter 60. The polarizing film 51 transmits P-polarized light in a predetermined polarization direction, in this embodiment, and reflects polarized light in a polarization direction orthogonal to this, and in this embodiment, reflects S-polarized light, and is incident on the polarizing film 51. As for the light, the S-polarized component is reflected by the polarizing film 51 and the P-polarized component is transmitted. The reflected S-polarized light component is reflected again by the adjacent reflection film 52 and emitted to the outside. On the other hand, since the phase difference plate 53 is disposed on the surface from which the P-polarized component transmitted through the polarizing film 51 is emitted, the P-polarized light is converted into S-polarized light and emitted. Therefore, all the light emitted from the polarization conversion element 1 is S-polarized light.

  By the way, as the phase difference plate 53 which is one of the components of the polarization conversion element 5 described above, a polycarbonate film has been conventionally used.

  However, the polarization conversion element 5 has a problem such as yellowing due to long-term aging such as heat of light.

In view of this, a polarization conversion element having improved heat resistance and durability using quartz as a phase difference plate which is one of the components of the polarization conversion element has been proposed (for example, see Patent Document 1).
JP 2003-302523 A (G02B 5/30)

  According to the configuration of Patent Document 1 described above, durability and heat resistance are improved, but there is a problem in that it is necessary to use an expensive member called quartz, which increases costs. Moreover, since the quartz phase difference plate is formed by cutting out an optical artificial quartz, there is a problem that the larger the phase difference plate, the higher the cost and the difficulty of formation.

  Therefore, an object of the present invention is to provide an inexpensive projection display device using a polarization conversion element.

  A projection display device according to the present invention includes an integrator optical system that divides light from a light source into a plurality of light beams, a polarization conversion element that aligns the polarization directions of the plurality of light beams from the integrator optical system with a predetermined polarization direction, In a projection display device comprising a light modulation element that is irradiated with a light beam from a polarization conversion element and forms an optical image according to a video signal, and a projection lens that displays the optical image in an enlarged manner, the polarization conversion element Of the incident light from the light source is reflected by the polarizing film that transmits the first polarized light in the predetermined polarization direction and reflects the second polarized light in the polarization direction orthogonal to the predetermined polarization direction. A reflective film that reflects the second polarized light is disposed inside the transparent member, and a plurality of reflection films are provided on either the first polarized light emission side or the second polarized light emission side of the transparent member. A phase difference plate divided into Wherein the polarization conversion unit is arranged.

  The plurality of phase difference plates may be arranged on the transparent member so that a gap between the divided phase difference plates corresponds to a position between light beams divided by the integrator optical system. .

  The retardation plate may be a quartz plate.

  Further, the phase difference plate near the center of the optical axis can be configured to use a crystal phase difference plate, and the other phase difference plates can be made of a resin phase difference plate.

  According to the present invention, a phase difference plate can be formed without cutting out a large crystal, and a large polarization conversion element can be easily produced at a relatively low cost. Further, since a quartz phase difference plate having excellent heat resistance and light resistance can be used, the life of the polarization conversion element can be extended.

  Further, in consideration of the temperature distribution given to the polarization conversion element, an excellent and inexpensive polarization conversion element having heat resistance and durability can be provided, and an inexpensive projection display apparatus can be provided.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated in order to avoid duplication of description.

  FIG. 3 is a configuration diagram for explaining an embodiment of the present invention, and shows a part of the first fly-eye lens 3, the second fly-eye lens 4 and the polarization conversion element 5 in an enlarged manner. FIG. 4 is a schematic cross-sectional view showing the polarization conversion element used in the present invention, and FIG. 5 is a perspective view showing the polarization conversion element in the embodiment of the present invention.

  The white light emitted from the light source unit 1 is emitted as parallel light by the parabolic reflector 2, and is composed of first and second fly-eye lenses 3 and 4 configured by a plurality of rectangular convex lens groups. The light beam is split by an ifile integrator optical system.

  The first fly-eye lens 3 is configured by arranging a plurality of rectangular convex lenses 3a vertically and horizontally, and the second fly-eye lens 4 is configured by arranging a plurality of rectangular convex lenses 4a vertically and horizontally. The light from the light source unit 1 is split by a first fly-eye lens 3 with a fly-eye lens, and each light beam is guided to an irradiation region as a bundle of a plurality of light beams by a second fly-eye lens 4. As a result, the luminance unevenness of the light source unit 1 is dispersed to obtain a uniform illuminance distribution on the irradiated surface.

  In this embodiment, the lens sizes of the lenses 3a and 4a of the first and second fly-eye lenses 3 and 4 are 7 mm in width and 5.4 mm in length.

  In this embodiment, a polarization conversion element 5 of 130 mm (F in the figure) × 130 mm (G in the figure) is disposed in proximity to the second fly-eye lens 4.

  As shown in FIG. 4, similarly to the polarization conversion element described above, the polarization conversion element 5 includes a polarization film 51 that forms an angle of 45 ° with respect to the optical axis of the optical system, a reflection film 52, and this polarization. And transparent members 50 sandwiching the film and the reflective film, respectively. And as the phase difference plate 530, it is comprised with the phase difference plate which consists of a quartz plate divided | segmented into plurality.

  For example, glass is used as the transparent member 50. A transparent member such as a glass plate having a polarizing film on the front surface and a reflective film on the back surface is disposed in close contact with each other at an angle of 45 degrees, and a predetermined emission surface and an incident surface are in contact with the polarizing film and the reflection film. The polarization conversion element 5 shown in FIGS. 4 and 5 is formed by cutting out so as to have an angle of 45 degrees. The phase difference plates 530 are attached to a predetermined position on the emission side surface of the transparent member 50 on the polarizing film 51 so as to be divided into two or more in the height direction of the polarization changing element.

  In this example, a retardation plate 530 is affixed, and a polarization conversion unit is configured by a transparent member portion sandwiching the polarizing film 51 and a transparent member portion sandwiching the adjacent reflection film 52. The pitch between the polarizing film 51 and the reflecting film 52 provided alternately is slightly larger than approximately ½ of the width of the lens cell 4a of the second fly-eye lens 4, and the width (H) is 3 in this embodiment. .5mm.

  As shown in FIG. 5, the polarization conversion unit in this embodiment has a function as one retardation plate by regularly arranging a plurality of rectangular retardation plates 530 in the vertical direction.

  The polarization conversion element 5 in this embodiment is divided into a plurality of phase difference plates 530... So that the gap between the divided phase difference plates 530 and 530 corresponds to the position between the light beams divided by the integrator optical system. The transparent member 50 is positioned and fixed using a jig or the like, and is fixed by using an adhesive.

  In this way, since the joints of the phase difference plates 530 and 530 are positioned corresponding to the positions between the light beams divided by the integrator optical system, no light is irradiated to the gaps between the joints. All the light beams from the optical system can be polarized and converted without waste.

  As in this embodiment, the lenses 3a and 4a of the first and second fly-eye lenses 3 and 4 are 7 mm wide and 5.4 mm long. The focal length of the integrator optical system is 43.3 mm. Further, the distance between the first and second fly-eye lenses 3 and 4 (A in the figure) is 40.7 mm, and the output of the second fly-eye lens 4 from the output of the first fly-eye lens 3 (B in the figure) is The distance (C in the figure) from the output of the second fly's eye lens 4 to the retardation plate of the polarization conversion element 5 is 5.5 mm.

  Under such design conditions, the effective size of the retardation film 530 is 3.4 mm in width and 5.1 mm in length. At this time, there is a gap of about 0.6 mm between the phase difference plates 530 and 530.

  Therefore, the polarization conversion shown in FIG. 5 is obtained by regularly arranging the phase difference plate 530 having a width of 3.4 mm and a length of 5.1 mm in the vertical direction (the height direction of the polarization conversion element) at intervals of 0.6 mm. Element 5 is obtained.

  Thus, in this embodiment, the 130 × 130 mm polarization conversion element 5 can be configured by using a plurality of quartz phase difference plates 530 having a horizontal size of 3.4 mm and a vertical size of 5.1 mm. Therefore, a phase difference plate can be formed without cutting out a large crystal, and a large polarization conversion element 5 can be easily produced at a relatively low cost. Further, since a quartz phase difference plate having excellent heat resistance and light resistance can be used, the life of the polarization conversion element 5 can be extended.

  In the above-described embodiment, the quartz phase difference plate 530 is provided corresponding to the number of the lenses 4a of the fly-eye lens 4. However, the number of the lenses 4a may not necessarily correspond to the effective height of the polarization conversion element. May be divided into a plurality of parts. FIG. 6 is a perspective view showing a polarization conversion element according to another embodiment used in the present invention.

  The polarization conversion element 5 shown in FIG. 6 uses a phase difference plate 530a corresponding to the number of two or more of the lens size and having a size divided into two with respect to the effective height of the polarization conversion element. Also in the case shown in FIG. 6, the joint between the phase difference plates 530a and 530a is made to correspond to the position between the light beams divided by the integrator optical system.

  Thus, when the number of retardation plates is reduced, the step of attaching the retardation plates is facilitated. The effective size of the retardation film 530 varies depending on various conditions depending on the integrator interval, focal length, lens size, and the like. Therefore, the number of divisions of the retardation plate to be used may be determined in consideration of the size of the retardation plate to be used, its cost, the attaching process, and the like. By the way, in the projection display apparatus, the light intensity increases from the center of the optical axis C, and the intensity decreases as it goes around. FIG. 7 is a perspective view showing an embodiment of a polarization conversion element corresponding to the light intensity.

  As shown in FIG. 7, a portion that becomes a high temperature region (about 90 ° C. to 100 ° C.) uses a crystal phase difference plate 530b divided into a plurality of portions in the height direction, and the other portion of the phase difference plate 531 is made of resin. It was made of a manufactured phase difference plate.

  In this way, by using an expensive crystal phase difference plate only for a portion that requires heat resistance and the like, and using an inexpensive resin phase difference plate 531 elsewhere, the distribution of temperature given to the polarization conversion element 5 can be obtained. The excellent polarization conversion element 5 having heat resistance and durability in consideration can be further provided at a reduced cost.

  As the resin phase difference plate 531, a polycarbonate, a cyclic olefin resin, a polycarbonate obtained by stretching a polycarbonate in a thickness direction by a special method, or a polycarbonate film into which a fluorene skeleton is introduced can be used.

  If the above-described polarization conversion element according to the present invention is used as the polarization conversion element 5 of the projection display device shown in FIG. 1, it can be provided with excellent durability and at low cost.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

It is a schematic diagram which shows the basic composition of the projection type display apparatus using a general illumination optical system. It is the schematic diagram which expanded and showed a part of 1st fly eye lens of FIG. 1, a 2nd fly eye lens, and a polarization conversion element. It is a block diagram for demonstrating embodiment of this invention, and has expanded and shown a part of 1st fly eye lens, 2nd fly eye lens, and a polarization conversion element. It is typical sectional drawing which shows the polarization conversion element used for this invention. It is a perspective view which shows the polarization conversion element in embodiment of this invention. It is a perspective view which shows the polarization conversion element in other embodiment of this invention. It is a perspective view which shows the polarization conversion element in further another embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 5 Polarization conversion element 51 Polarizing film 52 Reflecting film 50 Transparent member 530 Crystal phase difference plate

Claims (4)

An integrator optical system that divides the light from the light source into a plurality of light beams, a polarization conversion element that aligns the polarization directions of the plurality of light beams from the integrator optical system with a predetermined polarization direction, and a light beam from the polarization conversion element In the projection display device including a light modulation element that forms an optical image in response to a video signal and a projection lens that displays the optical image in an enlarged manner, the polarization conversion element includes the incident light from the light source. A polarizing film that transmits first polarized light in a predetermined polarization direction and reflects second polarized light in a polarization direction orthogonal to the predetermined polarization direction, and reflects the second polarized light reflected by the polarization film A reflective film is disposed inside the transparent member, and a plurality of divided retardation plates are provided on either the first polarized light exit side or the second polarized light exit side of the transparent member. A polarization conversion unit is provided. Projection display device comprising and. The plurality of divided retardation plates are arranged on the transparent member so that a gap between the divided retardation plates corresponds to a position between light beams divided by the integrator optical system. The projection display device according to claim 1. The projection display device according to claim 1, wherein the phase difference plate is formed of a quartz plate. The phase difference plate near the center of the optical axis is a quartz phase difference plate, and the other phase difference plate is a resin phase difference plate. Item 3. The projection display device according to Item 1 or 2.

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