JP4794195B2 - Projection display - Google Patents

Description

  The present invention relates to a projection display device using a light valve.

  As a method for obtaining a large screen image, a method of forming an image according to a video signal on a light valve and irradiating the image with light and then enlarging and projecting the optical image formed on the screen by a projection lens is often used. Known (for example, Patent Document 1). When a spatial light modulator that forms an optical image by controlling the traveling direction of light according to a video signal is used as the light valve, a high-luminance projection image with high light utilization efficiency can be displayed. Examples of the light valve include a transmissive light valve using liquid crystal and a reflective light valve using reflection. Hereinafter, a case where a reflective light valve is mainly used will be described as an example.

  In recent years, a digital micromirror device (hereinafter referred to as DMD) has attracted attention as a reflective light valve. In the DMD, a large number of minute reflecting mirrors (hereinafter referred to as minute mirrors) are two-dimensionally arranged on a silicon substrate, and each minute mirror constitutes a pixel. Each micromirror is configured to move like a seesaw within a range of ± θ degrees (usually θ is about 10). The DMD forms an optical image by controlling the light emission direction by tilting each micromirror by + θ degrees or −θ degrees in accordance with the video signal.

  9 and 10 are horizontal cross-sectional views showing the configuration of a conventional projection display device using a reflective light valve. As the optical unit for guiding the illumination light to the reflection type light valve and inputting the formed optical image to the projection optical system, the total reflection prisms 105A and 105B are used in the projection type display device shown in FIG. 9, and the projection shown in FIG. In the type display device, a convex lens 118 is used. Since any projection type display device has substantially the same configuration except for the optical unit, a conventional projection type display device using total reflection prisms 105A and 105B shown in FIG. 9 will be described as a representative. .

  An illumination optical system 110 that condenses and illuminates light emitted from a lamp 101 as a light source on a reflective light valve 106 includes a lamp 101, a concave mirror 102, a rod prism 103, and a condenser lens 104. The rod prism 103 has, for example, a quadrangular prism shape, and its cross section has an aspect ratio substantially equal to the effective display area of the reflective light valve 106. The concave mirror 102 has an elliptical cross-sectional shape, and has a first focal point and a second focal point. Further, the center of the light emitter of the lamp 101 is arranged so as to be located near the first focal point of the concave mirror 102, and the light incident surface of the rod prism 103 is arranged so as to be located near the second focal point of the concave mirror 102. Yes. The concave mirror 102 is formed by forming an optical multilayer film that transmits infrared light and reflects visible light on the inner surface of a glass substrate.

  The radiated light emitted from the lamp 101 is reflected and collected by the concave mirror 102, and forms a light emitter image of the lamp 101 at the second focal point of the concave mirror 102. The luminous body image of the lamp 101 is brightest in the vicinity of the center near the optical axis, and tends to become darker as the periphery becomes darker. This problem is that the entrance surface of the rod prism 103 is arranged near the second focal point of the concave mirror 102, and the incident light is multiple-reflected on the inner surface of the rod prism 103 to equalize the brightness. This is solved by using the mouth as a secondary light source. The secondary light source illuminates the reflective light valve 106 through the cover glass 107 through the condenser lens 104 and the surface 105a of the total reflection prism 105B, which is an optical unit, and the surface 105b of the total reflection prism 105B. The uniformity of the light 111 can be ensured.

In particular, when a DMD is used as a reflection type light valve, the reflected light beam of the illumination light 111 incident on the micromirror of the DMD becomes incident light 116 incident on the projection lens 109 when the micromirror is turned on. When the signal is OFF, the non-incident light 115 travels in a direction not incident on the projection lens. In this way, an image to be projected on the screen is formed by controlling the time distribution between the light at the ON signal and the light at the OFF signal in accordance with the video signal.
JP 2002-250894 A

  However, particularly in a projection display device using a reflective light valve, unnecessary projection light (hereinafter referred to as “unnecessary projection light”) having a predetermined brightness on the image projected on the screen is irrelevant to the necessary image. , Called unnecessary light). When unnecessary light reaches the screen, an image different from the original desired image (hereinafter referred to as a ghost) is formed, so that the image quality deteriorates. In recent years, as the brightness of projection display devices has improved, image quality degradation due to unnecessary light has become an increasingly serious problem.

  Unnecessary light is generated, for example, when the radiated light emitted from the lamp is repeatedly reflected between components such as a holder that supports the optical element, and finally passes through the projection lens and reaches the screen. There are mainly two causes for generating unnecessary light. One is that the illumination light emitted from the lamp is always reflected at the interface of optical elements having different refractive indexes, and the other is that the illumination light is imaged on the reflective light valve. This is because the illumination light reaches outside the effective display area of the light valve.

  FIG. 11 is a front view of the modeled reflective light valve. FIG. 11A shows a reflective light valve 106 and an effective display area 121 located in the center thereof. FIG. 11B shows an illumination light image 22 (hereinafter referred to as an illumination image) 22 formed on the reflective light valve 106 shown in FIG. 11A. Usually, the illumination image is configured to be slightly larger than the effective display area 121 of the reflective light valve 106, and thus the light reaching outside the effective display area 121 becomes unnecessary light.

  The illumination image is configured to be larger than the effective display area of the light valve. This is due to errors in assembling the illumination optical system and errors in the components, and there is a screen where the illumination image does not overlap in the effective display area. This is to prevent chipping of the upper projected image. Even if the size of the effective display area of the light valve and the size of the illumination image are perfectly matched, the illumination image always includes aberrations in optical design and errors during assembly of the illumination optical system. A part of the illumination image protrudes outside the effective display area of the light valve, and unnecessary light is generated.

  Further, when DMD is used as a reflection type light valve, all non-incident light that is reflected light at the time of OFF signal becomes unnecessary light. When the unnecessary light is repeatedly reflected between the optical element and the support member that supports the optical element and reaches the screen through the projection lens, a ghost is formed, which causes image quality deterioration.

  FIG. 12 is a horizontal sectional view showing a configuration of a conventional projection display apparatus using a total reflection prism. Hereinafter, an example in which unnecessary light reaches the screen in the conventional projection display device shown in FIG. 12 will be specifically described. The radiated light emitted from the lamp 101 passes through the rod prism 103 and the condenser lens 104, is totally reflected by the total reflection prism 105A, and enters the reflection type light valve 106. The illumination light incident on the reflective light valve 106 travels to the projection lens 109 when the micromirror is on, but conversely enters the total reflection prism 105B when the micromirror is off. Most of the unnecessary light incident on the total reflection prism 105B passes outside the total reflection prism 105B (117 in FIG. 12), but a part of the unnecessary light is reflected on the inside of the total reflection prism 105B and the support portion 112. Then, the light passes through the projection lens 109 and reaches the screen (122 in FIG. 12). In FIG. 12, of the support members, only the members that are in contact with the optical element are illustrated as support portions 112 to 114, and other support members are not illustrated.

  In the above, a typical example in which unnecessary light is reflected by the support unit 112 has been described. However, since various unnecessary light is scattered inside the projection display device, the other support unit 113 or 114 shown in FIG. There is also a possibility that unnecessary light reflected irregularly enters the projection lens 109.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a projection display device that can reliably prevent unwanted light from entering a projection lens and can substantially completely suppress ghost formation.

The present invention relates to an illumination optical system for condensing light from a light source to illuminate a light valve, an optical unit for guiding illumination light from the illumination optical system to a light valve, and illumination light guided by the optical unit. A light valve that reflects or transmits light to form an optical image, a projection optical system that projects the optical image formed by the light valve, and an optical element that constitutes the illumination optical system, the optical unit, the light valve, and the projection optical system. A projection-type display device comprising: a support unit supporting at least a part thereof, wherein the support unit periodically arranges structural units having a predetermined shape in an array at a pitch smaller than the shortest wavelength of the illumination light. The sheet having the antireflection structure formed thereon and having the sheet provided on the support portion is capable of absorbing the illumination light .

  Moreover, the antireflection structure is formed on a sheet, and the sheet may be attached to at least a part of the support portion. For example, the sheet may be made of a material that can absorb illumination light, or the sheet is made of a transparent material, and the support portion to which the sheet is attached is made of a material that can absorb illumination light. It may be a thing.

  Preferably, the structural units of the antireflection structure are periodically arranged in an array at a pitch of ½ or less of the shortest wavelength of illumination light.

  Preferably, the structural unit of the antireflection structure has a height of at least the pitch, and more preferably has a height of at least three times the pitch.

  Further, the structural unit of the antireflection structure may be a substantially conical protruding shape and / or a substantially conical depressed structure.

  Moreover, the material which can absorb illumination light may contain the dye for absorbing illumination light.

  ADVANTAGE OF THE INVENTION According to this invention, the projection type display apparatus which can prevent incidence | injection of the unnecessary light to a projection lens reliably, and can suppress formation of a ghost substantially completely is provided.

(First embodiment)
FIG. 1 is a horizontal sectional view showing a configuration of a projection display apparatus according to the first embodiment of the present invention. In FIG. 1, the projection display device includes an illumination optical system 10, a total reflection prism 5, a reflection light valve 6, a cover glass 7, a projection optical system 8, and support units 12 to 14.

  The illumination optical system 10 condenses the radiated light emitted from the lamp 1 as a light source and illuminates the reflective light valve 6 that is an illuminated surface. The illumination optical system 10 includes a lamp 1, a concave mirror 2, a rod prism 3, and a condenser lens 4. The projection optical system 8 includes a projection lens 9.

  The concave mirror 2 has an elliptical cross-sectional shape, and has a first focal point and a second focal point. The center of the light emitter of the lamp 1 is disposed so as to be positioned near the first focal point of the concave mirror 2, and the light incident surface of the rod prism 3 is disposed near the second focal point of the concave mirror 2. The concave mirror 2 is formed by, for example, forming an optical multilayer film that transmits infrared light and reflects visible light on the inner surface of a glass substrate.

  The cross section of the rod prism 3 has substantially the same aspect ratio as that of the effective display surface of the reflective light valve 6. For example, the rod prism 3 is a quadrangular prism or a glass prism prism having a mirror attached to the inner surface.

  First, the radiated light emitted from the lamp 1 is reflected and collected by the concave mirror 2 to form a luminous body image of the lamp at the second focal point of the concave mirror. The luminous body image of the lamp 1 is brightest in the vicinity of the center near the optical axis and tends to become darker as the periphery becomes darker. To solve this problem, the incident surface of the rod prism is disposed near the second focal point, the incident light is multiply reflected by the side surface of the rod prism 3 to equalize the luminance, and the exit surface of the rod prism 3 is used as the secondary light source. If an image is formed on the reflection type light valve 6 through the subsequent condenser lens 4 and the total reflection prism 5, the uniformity of the illumination light can be ensured. In the present embodiment, the illumination light means light used for forming an optical image among radiated light emitted from a light source.

  The condenser lens 4 collects the illumination light 11 from the secondary light source. In the present embodiment, for example, as shown in FIG. 1, a total reflection prism 5 </ b> A that is an optical unit and a rod prism 3 are provided. Arranged between. Note that only one condenser lens 4 may be arranged as shown in FIG. 1, but a plurality of condenser lenses 4 may be arranged in parallel on the optical axis, for example. It is also possible to use a lens in which the condenser lens 4 and the total reflection prism 5A are integrated.

  Next, the illumination light 11 condensed by the condenser lens 4 enters the total reflection prisms 5A and 5B. The total reflection prisms 5A and 5B are optical units for guiding the illumination light 11 to the reflection type light valve 6. The two total reflection prisms 5A and 5B are opposed to each other with the surfaces 5a and 5b through an air layer. Are joined together. By such joining, the illumination light 11 incident on the surface 5a of the total reflection prism 5A can be totally reflected by the surface 5b of the total reflection prism 5B and incident on the reflection type light valve 6.

  The reflective light valve 6 is a DMD, for example, and reflects the guided illumination light 11 to form an optical image. In the DMD, a large number of micromirrors arranged two-dimensionally on a substrate each constitute a pixel, and the reflection direction of each micromirror can be switched independently to two directions (a sandwich angle of about 20 degrees). it can. The switching of the reflection direction is performed by ON / OFF control of a video signal input to the DMD using each micromirror as a pixel. The reflected light beam of the illumination light 11 incident on the minute mirror becomes incident light (ON light) 16 incident on the projection lens 9 in order to project an optical image when the minute mirror is ON, and conversely, The non-incident light (OFF light) 15 travels in a direction not incident on the projection lens. In this way, by changing the tilt of each micromirror and controlling the time distribution between the light at the ON signal and the light at the OFF signal according to the video signal, only the desired reflected light is converged on the screen and projected. An image to be formed can be formed.

  The support parts 12 to 14 are part of a support member (holding tool) that supports at least a part of the optical elements included in the projection display device. The optical element is, for example, an element constituting the illumination optical system 10, the projection optical system 8, the optical unit, or a reflection type light valve. In FIG. 1, only the members that are in contact with the optical element among the support members are illustrated as support portions 12 to 14, and other support members are not illustrated. The support member 12 is disposed on a part of the surface of the total reflection prism 5B facing the projection optical system 8, and supports the total reflection prism 5B. The support member 13 supports the reflective light valve 6 and the total reflection prism 5A. The support member 14 is disposed on a part of the surface of the total reflection prism 5A facing the reflection type light valve 6, and supports the total reflection prism 5A.

  A major feature of the projection display device according to the present embodiment is that the support portions 12 to 14 are made of a material capable of absorbing illumination light, and the antireflection structure 23 is formed on at least a part of the support portions 12 to 14. It is that. Thereby, the support parts 12-14 can reduce reflection of the unnecessary light (unnecessary light) in the illumination light 11, and can absorb it inside. Hereinafter, reduction of unnecessary light by the support portions 12 to 14 and the support portions 12 to 14 will be described in detail with reference to the drawings.

  FIG. 2 is a diagram showing an optical path through which incident light 16, non-incident light 15 and unnecessary light pass in the projection display device shown in FIG. In FIG. 2, the optical path through which incident light 16 and non-incident light 15 pass is indicated by a solid line, and the optical path through which unnecessary light passes is indicated by a dotted line.

  The illumination light 11 emitted from the condenser lens 4 is reflected by the surface 5a of the total reflection prism 5A and enters the reflection type light valve 6. Here, a part of the illumination light 11 incident on the reflective light valve 6 travels outside the effective display area of the reflective light valve 6. A part of the illumination light 11 traveling outside the effective display area is reflected by the support portion 13 and passes through the total reflection prism 5B and enters the projection lens 9 (21 in FIG. 2). When the micromirror is OFF, most of the non-incident light 15 reflected by the reflective light valve 6 passes outside the total reflection prism 5B and does not enter the projection lens 9 (17 in FIG. 2). A part of the light 15 is reflected by the total reflection prism 5B and the support part 12, and enters the projection lens 9 (22 in FIG. 2). When these unnecessary lights 21 and 22 are incident on the projection lens 9, a ghost is formed.

  However, in the projection display device according to the present embodiment, the support portions 12 to 14 are made of a material that can absorb illumination light, and at least part of the support portion 12 to 14 is formed with an antireflection structure, so that the above-described unnecessary Since the generation of reflected light can be sufficiently prevented and absorbed in the support portions 12 to 14, unnecessary light can be greatly reduced to the extent that it is not comparable to conventional projection display devices.

  FIG. 3A is an enlarged view of the total reflection prism 5B and the support portion 12 shown in FIG. In the support part 12, the part in which the antireflection structure 23 is formed is shown by oblique lines. As shown in FIG. 3A, an antireflection structure 23 is formed on at least a part of the surface where the non-incident light 22 which is unnecessary light reaches, that is, the surface facing the total reflection prism 5B. 3A shows a case where the antireflection structure 23 is formed on the entire surface facing the total reflection prism 5B, but the antireflection structure body is not necessarily formed on the entire surface facing the total reflection prism 5B. 23 need not be formed, and the antireflection structure 23 may be formed at least partially.

  Moreover, as shown in FIG. 3B, in the support part 12, not only the surface facing the total reflection prism 5B but also the antireflection structure 23 may be formed on the side surface of the surface. As described above, the support 12 is made of a material capable of absorbing illumination light, and at least part of the support 12 is formed with the antireflection structure, so that it passes through the total reflection prism 5B and is formed on the side surface of the support 12. It is possible to prevent reflection of unnecessary light that reaches. Since the unnecessary light that reaches the side surface of the support portion 12 has the same wavelength as the illumination light, the unnecessary light is reflected by the material that can absorb the illumination light that forms the antireflection structure 23 and the support portion 12. It can be suppressed substantially completely.

  In FIG. 3, the support portion 12 has been described as an example, but the support portions 13 and 14 similarly have an antireflection structure formed on at least a part of the surface. In the support portion 14 that supports the total reflection prism 5A, the antireflection structure 23 is preferably formed on at least a part of the surface where the illumination light reaches, that is, the surface of the support portion 14 that faces the total reflection prism 5A. It is good to be.

  FIG. 4A is a horizontal sectional view of the enlarged support portion 13. As shown in FIG. 4A, an antireflection structure 23 may be formed on the surface facing the reflection type light valve 6 and the total reflection prism 5A, and as shown in FIG. 4B, the reflection type light valve 6 and The antireflection structure 23 may be formed on the surface facing the total reflection prism 5A and on the side surface thereof.

  The antireflection structure 23 is a wavelength of illumination light in which a structural unit having a predetermined shape becomes unnecessary light (light reflected by the total reflection prisms 5A and 5B and reaching the surfaces of the support portions 12 to 14). The lower limit of (usually about 400 to 700 nm), that is, the electrodes are periodically arranged in an array at a pitch smaller than the shortest wavelength of illumination light. By periodically arranging the structural units having a predetermined shape in an array, the apparent refractive index of the illumination light is continuously changed, and the transmission / reflection characteristics at the interface with the air layer. It is possible to form an antireflection functional surface with little incidence angle dependency and wavelength dependency.

  In addition, the said pitch means the pitch in the densest arrangement direction, when the reflection preventing structure 23 is comprised by the two-dimensional arrangement | sequence of many fine structure units.

  Further, the antireflection structure 23 means a member having a fine structure formed on the surface in order to prevent reflection of illumination light whose reflection should be reduced, and only an aspect in which the light whose reflection should be reduced is not completely reflected. Instead, it also includes an aspect having an effect of preventing reflection of light whose reflection at a predetermined wavelength should be reduced.

  As the antireflection structure 23 that can be used in this embodiment, for example, conical protrusions having a height H1 as shown in the schematic enlarged view of FIG. 5A are used as structural units, and these conical protrusions have a pitch P1. Examples of the structure are periodically arranged in an array.

  The pitch P1 of the structural unit is substantially constant in one arrangement direction in the antireflection structure 23, and may be smaller than the shortest wavelength of the illumination light. However, the transmission unit / transmission characteristics at the interface depend on the incident angle. From the viewpoint that the wavelength dependency can be further reduced, the pitch P1 is preferably ½ or less, more preferably １ ／ or less of the shortest wavelength of illumination light. For example, considering the manufacturability of the antireflection structure 23 as described later, it is desirable that the pitch P1 has a certain size, and is preferably about 1/5 or more of the shortest wavelength of normal illumination light.

  The height H1 of the structural unit is not particularly limited, and the height H1 of all the structural units in the antireflection structure 23 may not necessarily be constant, but the higher the height H1, the more the illumination light There is an advantage that an antireflection function for unnecessary light is improved. Accordingly, the height H1 of the structural unit is at least the pitch P1 or more (the minimum structural unit height is at least the pitch), and at least three times the pitch P1 (the minimum structural unit height is three times the pitch). Or more). Note that, for example, considering the manufacturability of the antireflection structure 23 as described later, it is desirable that the height H1 is up to a certain size, and usually not more than about 5 times the pitch P1 (the largest structural unit). Is preferably about 5 times the pitch or less).

  However, the structure of the antireflection structure 23 is not necessarily limited to the conical structure shown in FIG. 5A. For example, the structural unit has a regular hexagonal pyramid shape or a pyramid shape such as a quadrangular pyramid shape (FIG. 5B). It may be a structure. Further, the shape of such a structural unit is not necessarily limited to a conical shape, and even if it is a columnar shape (FIG. 6A) or a prismatic shape (FIG. 6B), it has a bell shape (FIG. 7A and FIG. 7B) may be a truncated cone shape such as a truncated cone shape (FIG. 8A) or a truncated pyramid shape (FIG. 8B). Moreover, each structural unit does not need to be a strict geometric shape, and may be substantially a cone shape, a column shape, a bell shape, a frustum shape, or the like.

  Further, in FIGS. 5 to 8, the antireflection structure 23 has a structural unit having a protruding shape. However, the present embodiment is not limited to such a protruding shape. An antireflection structure 23 formed such that concavity-shaped, columnar, bell-shaped, truncated cone-shaped structural units are periodically arranged in an array at a pitch smaller than the shortest wavelength of illumination light. It is also possible to use it. Further, the protruding shape structural unit and the depressed shape structural unit may be simultaneously present in one antireflection structure 23. In addition, in the case of the antireflection structure 23 in which such a protruding-shaped structural unit and a depressed-shaped structural unit exist at the same time, the sum of the height of the protruding portion and the depth of the depressed portion is within the range of the height H1. It is preferable. As described above, in the antireflection structure 23 used in the present embodiment, each structural unit is periodically arranged in an array at a pitch smaller than the shortest wavelength of the illumination light, and sufficiently prevents reflection of unnecessary light. The shape of the structural unit is not particularly limited as long as the structure can be used.

  In the present embodiment, the refractive index of the illumination light continuously changes at the air interface, and the reflection of unnecessary light can be more sufficiently prevented. Alternatively, it is preferable to use the antireflection structure 23 having a substantially conical depression shape. When the substantially conical shape is a substantially regular hexagonal pyramid shape, the structural units are arranged with a high filling rate, and the illumination light is transmitted at the air interface. This is particularly preferable from the viewpoint of further improving the transmission characteristics of illumination light such that the refractive index further changes continuously.

  The material that can absorb the illumination light that constitutes the support portions 12 to 14 is not particularly limited as long as it is a material that can normally absorb the illumination light having a wavelength of about 400 to 700 nm. For example, a black material is preferably used. Can be used. Such black materials include, for example, black dyes obtained by mixing pigments such as cyan, magenta, and yellow in resins such as polycarbonate resins and acrylic resins (for example, Plaster Black 8950, Plaster Black 8970 (both trade names, Arimoto Chemical Industry Co., Ltd.)) or a pigment such as carbon black.

  Although there is no particular limitation on the manufacturing method of the support portions 12 to 14 according to the present embodiment, for example, a pattern is drawn on a quartz glass substrate or the like by a method such as electron beam drawing, and processing such as dry etching is performed. After forming a high-precision master mold that has been precisely machined into the same shape as the antireflection structure 23 in advance, the master mold is used to press-mold a heat-softened glass material to form an antireflection structure made of glass. For example, there is a method in which a mold that can absorb illumination light such as the black material (black resin) is subjected to press molding using a mold for forming an antireflection structure. When such a method is employed, the support portions 12 to 14 having the antireflection structure 23 on at least a part of the surface thereof can be manufactured at a low cost and in large quantities.

  In addition to the above, when manufacturing the support parts 12 to 14 according to the present embodiment, for example, metals such as aluminum, brass, and aluminum magnesium alloy are used, and molding, etching, X-ray lithography, photolithography, etc. It is also possible to adopt a method of appropriately combining the above. In addition, since the intensity | strength of the illumination light 11 normally radiate | emitted from the rod prism 3 is high, as mentioned above, the reflected light which reaches | attains the support parts 12-14 also has a certain amount of intensity | strength. Therefore, since the vicinity of the support parts 12-14 may become comparatively high temperature, it is more preferable to use a material made of a heat-resistant material such as the metal as the support parts 12-14. it can.

  Moreover, since the support parts 12-14 which concern on this embodiment have the antireflection structure 23 formed in the surface, the surface of the base material 24 in which the antireflection structure 23 is formed, and the support parts 12-14 The optical element supported by is disposed at a position separated by at least the height H1 of the antireflection structure. On the other hand, if the distance between the support portions 12 to 14 and the optical element supported thereby is too large, it is difficult to achieve the object of the present invention. Moreover, the support parts 12-14 and the optical element supported by it may be connected by connection members, such as an L-shaped member, for example.

  As described above, the support unit according to the present embodiment is made of a material capable of absorbing illumination light, and the structural units having a predetermined protruding shape or depression shape are periodically arrayed at a pitch smaller than the shortest wavelength of the illumination light. Since the arrayed antireflection structure is formed on at least a part thereof, unnecessary light in the illumination light is sufficiently prevented from being reflected at the interface with the air, and incident unnecessary light is substantially prevented. Can be completely absorbed.

  Note that, as described above, the projection display device according to the present embodiment includes an illumination optical system, an optical unit, a reflective light valve, a projection optical system, and a support unit, and the support unit is made of a material that can absorb illumination light. As long as the antireflection structure is formed at least in part, the structure is not particularly limited. Therefore, the projection type display device may be a front type projection type display device as shown in FIG. 1, for example, or may be a rear type projection type display device.

(Second Embodiment)
Next, a projection type display apparatus according to a second embodiment of the present invention will be described with reference to the drawings.

  The basic configuration of the projection display device according to the present embodiment is the same as that of the first embodiment, but the antireflection structure 23 included in at least a part of the support portions 12 to 14 and the material capable of absorbing illumination light are used. The configuration is different from that of the first embodiment. The present embodiment is characterized in that a sheet having an antireflection structure 23 is stuck on a base material constituting the support portions 12 to 14.

  The base material which comprises the support parts 12-14 has the magnitude | size which includes the desired light beam which should be absorbed, mechanical strength, and thickness required for a structure. A base material will not be specifically limited if it is a material which can absorb illumination light, For example, a black material can be used suitably. As in the first embodiment, the black material is a black dye obtained by mixing a pigment such as cyan, magenta, or yellow in a base material such as polycarbonate resin or acrylic resin (for example, Plaster Black 8950, Plaster Black 8970). (All are trade names, manufactured by Arimoto Chemical Co., Ltd.)) and pigments such as carbon black.

  A sheet | seat consists of transparent materials, such as an acrylic resin, for example, and has the reflection preventing structure 23 formed in the pitch smaller than the shortest wavelength of illumination light in at least one part of the surface. The thickness of the sheet is not limited as long as it is easy to handle and sufficient mechanical strength can be obtained, but is preferably 10 μm or more.

  The height and pitch of the antireflection structure 23 may be determined in the same manner as in the first embodiment, and the antireflection structure 23 has a pitch smaller than the shortest wavelength of illumination light and a height higher than the pitch. Have

  Moreover, the difference in refractive index between the sheet and the substrate is 0.2 or less. By setting the difference in refractive index between the sheet and the base material to 0.2 or less, the reflectance generated at the interface between the sheet and the base material can be suppressed to a level that does not cause a problem. Furthermore, the difference in refractive index between the sheet and the substrate is desirably 0.1 or less. By setting the difference in refractive index between the sheet and the substrate to 0.1 or less, it becomes possible to further reduce the reflectance generated at the interface between the sheet and the substrate, and to effectively suppress the generation of stray light. it can.

  As described above, the sheet on which the antireflection structure 23 is formed and the substrate to which the sheet is attached can be bonded using, for example, an ultraviolet curable resin. In addition, it is good also as manufacturing the sheet | seat itself which has the antireflection structure 23 in at least one part with ultraviolet curable resin.

  Although the manufacturing method of the sheet | seat which has the reflection preventing structure 23 is not specifically limited, For example, a sheet | seat can be manufactured as follows. For example, after a pattern is drawn on a quartz glass substrate or the like by a method such as electron beam drawing and processing such as dry etching is performed to form a high-precision master mold that has been precisely processed into the same shape as the antireflection structure 23 in advance, The master mold is used to produce a glass antireflection structure molding die by press molding a heat-softened glass material, and the antireflection structure molding die is used, for example, for the acrylic resin or the like. For example, the material may be subjected to press molding. When such a method is employed, a sheet having at least a part of the antireflection structure 23 can be manufactured at low cost and in large quantities.

  The acrylic resin used for press molding preferably has a thickness of 10 μm or more (sheet thickness + 0.15 μm) from the viewpoint of easy handling and mechanical strength. Thereby, the sheet | seat which is easy to handle and has sufficient mechanical strength can be manufactured.

  As described above, according to the present embodiment, the unnecessary illumination light that is incident on the surface of the base material made of a material that can absorb illumination light is attached to the surface of the base material by attaching the sheet having the antireflection structure 23 to the air. It is possible to sufficiently prevent reflection at the interface between the two and the incident unnecessary illumination light substantially completely. Therefore, an antireflection function can be imparted to the target structure at low cost and easily.

  Further, in the present embodiment, the sheet material is described as being an acrylic resin, but the sheet material is not limited to this, for example. A polycarbonate resin, a polyethylene terephthalate resin, etc. can also be used.

  In the present embodiment, a transparent material is used as a material for the sheet. However, the material is not necessarily limited to the transparent material, and is colored black by a material that can absorb illumination light, for example, a dye or a pigment. A black material may be used. By using a sheet made of a material that can absorb illumination light, it is possible to further improve the absorption efficiency of illumination light. In addition, when a sheet | seat consists of a material which can absorb illumination light, the base material on which a sheet | seat is affixed does not necessarily need to be comprised with the material which can absorb.

  In the present embodiment, the case where a structural unit having a conical shape (for example, FIG. 5A) is used as an example of the antireflection structure has been described as an example. However, as in the case of the first embodiment, the antireflection structure is used. The structural unit is not necessarily limited to such a structure. For example, the structural unit may be a structure having a pyramid shape (FIG. 5B) such as a regular hexagonal pyramid shape or a quadrangular pyramid shape. Further, the shape of such a structural unit is not necessarily limited to a conical shape, and even if it is a columnar shape (FIG. 6A) or a prismatic shape (FIG. 6B), it has a bell shape (FIG. 7A and FIG. 7B) may be a truncated cone shape such as a truncated cone shape (FIG. 8A) or a truncated pyramid shape (FIG. 8B). Moreover, each structural unit does not need to be a strict geometric shape, and may be substantially a cone shape, a column shape, a bell shape, a frustum shape, or the like. As in the first embodiment, the structural unit of the antireflection structure may be a protruding shape, or may be a depressed shape.

  In the first and second embodiments, the case where the projection display device includes the reflection type light valve has been described as an example. However, the light valve included in the projection display device may be a liquid crystal light valve. In addition, the support portion on which the antireflection structure is formed has been described as supporting at least one of the optical unit and the reflection type light valve. However, the present invention is not limited to this, and an optical element included in the projection display device is provided. By forming the supporting bracket, the case, and the like to be supported by a base material capable of absorbing illumination light and forming an antireflection structure, unnecessary projection images can be remarkably reduced, and high-quality images can be formed.

  INDUSTRIAL APPLICABILITY The present invention is useful as a projection display device that can reliably prevent unwanted light from entering the projection lens and can substantially completely suppress the formation of ghosts.

1 is a horizontal sectional view showing a configuration of a projection display device according to a first embodiment of the present invention. 1 is a diagram showing an optical path through which incident light 16, non-incident light 15 and unnecessary light pass in the projection display device shown in FIG. Enlarged view of the total reflection prism 5B and the support 12 shown in FIG. Enlarged view of the total reflection prism 5B and the support 12 shown in FIG. Enlarged view of the support portion 13 shown in FIG. Enlarged view of the support portion 13 shown in FIG. It is a schematic enlarged view which shows an example of the antireflection structure 23 used for this invention, and is a figure of a structure whose structural unit is a cone shape It is a schematic enlarged view which shows an example of the antireflection structure 23 used for this invention, and is a figure of a structure whose structural unit is a pyramid shape It is a schematic enlarged view which shows an example of the antireflection structure 23 used for this invention, and is a figure of a structure whose structural unit is a column shape It is a schematic enlarged view which shows an example of the antireflection structure 23 used for this invention, and is a figure which shows a structure whose structural unit is a prism shape It is a schematic enlarged view which shows an example of the reflection preventing structure 23 used for this invention, and is a figure which shows a structure in which a structural unit is a bell-shaped. It is a schematic enlarged view which shows an example of the reflection preventing structure 23 used for this invention, and is a figure which shows a structure in which a structural unit is a bell-shaped. It is a schematic enlarged view which shows an example of the antireflection structure 23 used for this invention, and is a figure which shows a structure whose structural unit is a truncated cone shape It is a schematic enlarged view which shows an example of the antireflection structure 23 used for this invention, and is a figure which shows a structure whose structural unit is a truncated pyramid shape It is a horizontal sectional view which shows an example of a structure of the conventional projection type display apparatus, and uses a total reflection prism as an optical unit. It is a horizontal sectional view showing an example of the configuration of a conventional projection display device, using a convex lens as an optical unit Front view of reflective light valve Front view of reflective light valve Relationship diagram of projection display device showing generation of unnecessary light

Explanation of symbols

1, 101 Lamp 2, 102 Concave mirror 3, 103 Rod prism 4, 104 Condenser lens 5A, 5B, 105A, 105B Total reflection prism 5a, 5b, 105a, 105b Surface 6, 106 Reflection type light valve 7, 107 Cover glass 8, 108 Projection optical system 9, 109 Projection lens 10, 110 Illumination optical system 11, 111 Illumination light 12, 13, 14, 112, 113, 114 Support part 15, 115 Non-incident light 16, 116 Incident light 118 Convex lens

Claims (1)

An illumination optical system that collects light from the light source to illuminate the light valve, an optical unit that guides illumination light from the illumination optical system to the light valve, and reflects or transmits illumination light guided by the optical unit. A light valve for forming an optical image, a projection optical system for projecting the optical image formed by the light valve, and at least a part of the optical elements constituting the illumination optical system, the optical unit, the light valve, and the projection optical system. An anti-reflection device comprising a support unit for supporting, wherein the support unit is configured by periodically arranging structural units of a predetermined shape in an array at a pitch smaller than the shortest wavelength of the illumination light. A projection-type display device comprising: a sheet having a structure and a sheet provided on the support portion capable of absorbing the illumination light .

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