JP2006030461A - Wave plate, stereoscopic image display device, and method of manufacturing wave plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a manufacturing cost of a wave plate with respect to the wave plate, a stereoscopic image display device, and a method of manufacturing the wave plate. <P>SOLUTION: A minute periodical structure of grooves 2 is directly formed on a substrate 4, and two areas A and B where the directions of optical axes of transmitting light are different from each other are alternately formed in the minute periodical structure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wave plate that changes the polarization state of light, in particular, a wave plate used in a 3D display device, a 3D image display device including the wave plate, and a method of manufacturing the wave plate.

  As shown in FIG. 12, in the conventional wave plate manufacturing process, the first retardation film 102 is attached to the substrate 101 (a), and the first retardation film 102 is partially removed by the dicing saw 103. After (b) and (c), the second retardation film 104 is affixed so that the direction of the optical axis is different from that of the first retardation film 102 (d) and overlapped on the first retardation film 102. By removing the part with the dicing saw 103 (e), the wave plate 105 having regions with different optical axes is formed.

  Further, as shown in FIG. 13, after the retardation film 112 is attached to different substrates 111 so that the directions of the optical axes are different (a) and (d), each is partially removed by a dicing saw 113 (b) (E) The two retardation films 112 of each substrate 111 are bonded so that they do not overlap (g), and one of the substrates 111 is removed, so that the wavelength plate 114 having regions with different optical axes is obtained. It is also known to configure (see Patent Document 1 above).

  Further, in the conventional wave plate manufacturing process shown in FIG. 14, the first retardation film 122 is attached to the substrate 121 (a), and the resist pattern 123 formed by the photolithography process is used as the mask (b) (c). The retardation film 122 is partially removed by etching (d), the resist pattern 123 is removed (e), and then the second retardation film 124 is optically oriented with respect to the first retardation film 122. Affixed differently (f), the portion overlapping the first retardation film 122 is similarly masked with the resist pattern 125 formed in the photolithography process (g) removed by etching (h), and the resist pattern By removing 125, a wave plate 126 having regions with different optical axes is configured (i) (j). Similarly to the above-described conventional wave plate 114, a retardation film is attached to a different substrate so that the directions of the optical axes are different, and the resist pattern formed by the photolithography process is used as a mask for partial etching. After the retardation film is removed and the resist pattern is removed, the retardation films of the respective substrates are bonded so as not to overlap each other, whereby a wave plate having regions having different optical axes can be configured.

  In addition, by configuring the stereoscopic display device 131 shown in FIG. 15 using the wave plate 126 (phase difference pieces 132 to 135) shown in FIG. A stereoscopic image can be observed by wearing polarized glasses. FIG. 16 is an explanatory diagram showing the arrangement of the wave plate 126, the polarizing film 136, and the alignment film 137 in the stereoscopic display device 131 shown in FIG. 15 (see Patent Document 2 above).

JP-A-10-160933 JP 10-161108 A

  However, in the case of the conventional wave plate described with reference to FIGS. 1 and 3, it is necessary to perform the process of attaching the retardation film to the substrate and partially removing the retardation film twice, In the process of partially removing the retardation film for the second time, it is necessary to perform a process of aligning with the retardation film that has been previously attached to the substrate and partially removed, and the process is complicated. There is a problem that the manufacturing cost cannot be reduced.

  Furthermore, the board | substrate which passed through the process of affixing the phase difference film of the 1st time and removing it partially has a part in which a phase difference film exists, and a part which does not exist, and an unevenness | corrugation exists. The second retardation film is attached to the surface of the unevenness, but it is very difficult to attach the retardation film without any gap at the step of the boundary of the unevenness. Therefore, a slight gap is generated between the phase difference pieces, and when the size of the phase difference piece is reduced, the size is limited. This is not a problem when the display pixel density is low, but when the display pixel density is increased as the image quality is improved, the size limit of the phase difference piece becomes a serious problem.

  Further, in the case of the conventional wave plate described with reference to FIG. 2, the step of attaching the retardation film to one substrate and partially removing it may be performed only once. To configure, two substrates are required, and when the two substrates are bonded, an alignment process and a process of removing one of the substrates are necessary, leading to an increase in manufacturing cost. There is a bug. In this case, after bonding the two substrates, it is possible to function as a wave plate without removing one of the substrates. However, since the thickness of one substrate is added, the thickness of the wave plate is increased. There is also a problem that the optical element cannot be made compact by nearly double.

  Even when these two substrates are bonded together, it is very difficult to eliminate the gap between the retardation pieces at all, and the retardation films do not overlap each other when the substrates are bonded together. Since it is necessary to take a margin of the positional accuracy when partially removing the substrate and the positional accuracy of the substrate bonding, there is a slight gap between the phase difference pieces, and the size of the phase difference piece was reduced. In some cases, the size is limited. This is not a problem when the display pixel density is low, as in the case of the conventional wave plate described with reference to FIGS. 1 and 3, but the display pixel density is increased as the image quality is improved. In some cases, the size limit of the retarder becomes a serious problem.

  An object of the present invention is to reduce the manufacturing cost of the wave plate.

  (1) The present invention provides a wave plate for changing the polarization state of light, comprising a substrate and a fine periodic structure directly formed on the substrate, wherein the fine periodic structure has an optical axis of the transmitted light. The wave plate is characterized in that two regions having different directions are alternately formed.

  (2) According to another aspect of the present invention, there is provided a wave plate manufacturing method for manufacturing a wave plate that changes a polarization state of light. The wavelength is characterized in that it is directly formed so that two regions having different axis directions are alternately formed, and each region is formed at once by forming an etching mask on the substrate and performing dry etching. It is a manufacturing method of a board.

  According to the invention of (1), each region of the wave plate in which two regions having different optical axis directions are alternately formed can be directly formed on the substrate with a fine periodic structure. Manufacturing is easy and manufacturing cost can be reduced.

  According to the invention of (2), the wavelength plate of (1) can be easily manufactured, and the manufacturing cost can be reduced.

  The best mode for carrying out the invention will be described.

  First, a wave plate according to an embodiment of the present invention will be described.

FIG. 1 is a plan view of the wave plate 1 of the present embodiment, and FIG. 2 is a longitudinal sectional view of a partial region of the wave plate 1. As shown in FIG. 2, grooves 2 are formed in a fine cycle in each region A (A _{1 to An} ) and B (B _{1 to} B _m ) in FIG. FIG. 2 is a cross-sectional view taken along a plane perpendicular to the groove 2. Region A1 in FIG. 1, ..., the A _n, the direction of the grooves 2 formed has a same direction, the region B _1, ..., even in B _m, the direction of the grooves 2 formed Are in the same direction, but the direction of the grooves is different between the regions A _{1 to An} and the regions B _{1 to} B _m . The regions A _{1 to An} and the regions B _{1 to} B _m are arranged alternately.

Originally, a fine periodic structure (FIG. 3) in which flat plates 3 having different refractive indexes that do not have birefringence characteristics (projections 5 between grooves 2 in FIG. 2) are arranged with a period sufficiently smaller than the wavelength of light (<λ / 2). Are known to generate birefringence properties (see "Principle of Optics, Max Born and Emil Wolf, PERGAMON PRESS LTD."). Even when grooves are formed on the substrate with a fine period, the structure is the same as the structure of FIG. 3 in which the flat plates 3 having different refractive indexes are arranged with a fine period, birefringence characteristics occur, and the polarization direction of light parallel to the flat plate Refractive index n _// and vertical light refractive index n _{そ れ ぞ れ} are respectively

It becomes. Here, n ₁ and n ₂ are the refractive index of the material in which the fine periodic structure is formed and the refractive index of the material filling the groove 2, respectively, and t is the duty ratio of the fine periodic structure, When the thickness is W ₁ and the distance between the flat plates 3 is W ₂ ,

It is.

  As described above, in the structural birefringence, the direction of the optical axis (slow axis and fast axis) can be arbitrarily determined by the direction in which the flat plates 3 are arranged (the direction in which the grooves are formed). The direction perpendicular to the flat plate 3 (direction perpendicular to the groove) is the fast axis.

Therefore, the direction of the optical axis of the light transmitted on the substrate 4 is changed so that two regions (in this example, the region A and the region B) that are different from each other due to the difference in the fine periodic structure are alternated. The wave plate 1 is manufactured by forming directly on the substrate 4. In this example, the grooves 2 are formed on the same substrate 4 with a fine period so that the directions of the optical axes are different between the regions A _{1 to An} and the regions B _{1 to} B _n . Thus, two regions (region A and region B) having different optical axes can be easily formed on the wave plate 1 alternately, and each region A _{1 to An} and region B _{1 to} B can be formed. The optical axis with _m can be arbitrarily determined.

  Therefore, the wave plate 1 can be easily manufactured as compared with the conventional case, and the manufacturing cost of the wave plate 1 can be reduced.

  The phase difference (delay amount) Re in each region is expressed by the following equation (4), where d is the height of structural birefringence (depth of the groove 2), and the substrate material (refractive index) and The phase difference (delay amount) can also be controlled by the material filling the groove (refractive index), the duty ratio of the fine periodic structure, and the height of the structure birefringence (groove depth).

In the wave plate 1 of the present embodiment, the grooves 2 in the regions A _{1 to An and} the grooves 2 in the regions B _{1 to} B _m are formed so as to be orthogonal to each other so that the optical axes are orthogonal. and which, when the phase difference both regions was a quarter of the wavelength of light, so that the polarization direction is + 45 ° linearly polarized light of a wavelength plate 1 with respect to the optical axis of the region a ₁ to a _n Is incident on the optical axis of the regions B _{1 to} B _m at −45 °. Accordingly, the light incident on the wave plate 1 becomes light also circularly polarized light transmitted through any of the regions (regions _A 1 to A _n and the area _B 1 .about.B _m), and light transmitted through the area _A 1 to A _n The rotation direction of the circularly polarized light is reversed with the light transmitted through the regions B _{1 to} B _m .

A design example of the wave plate 1 of the present embodiment will be described. The wavelength is designed to be 550 nm, and a groove having a width of 100 nm and a depth of 1.63 m is formed on the quartz substrate 4 as regions A _{1 to An} and regions. It is conceivable to form the wave plate 1 by forming it with a period of 200 nm so that the directions of the grooves 2 are perpendicular to each other with B _{1 to} B _m .

  Next, an example of a specific method for manufacturing the wave plate 1 of the present embodiment will be described.

  FIG. 4 is an explanatory view showing a process of forming the groove 2 having a fine periodic structure in the quartz glass substrate 4. First, a line and space pattern is formed with a resin material 11 on a quartz glass substrate 4 (a). Next, the metal film 12 is formed by vacuum deposition (b), and immersed in a chemical solution that dissolves the resin to form the metal film pattern 13 by the lift-off method (c). Then, the quartz glass substrate 4 on which the metal film pattern 13 is formed is dry-etched using a fluorocarbon gas such as CF4, C4F8, and CHF3 to form the grooves 2 having a fine periodic structure (d). Finally, the metal film pattern 13 is removed to complete the wave plate of the present embodiment (e).

  As the dry etching apparatus, an ECR etching apparatus, an ICP etching apparatus, or the like can be used.

  As a method for forming a line-and-space pattern having a fine period with the resin material 11 on the quartz glass substrate 4 described with reference to FIG. 4A, an EB resist is formed on the quartz glass substrate 4. An EB lithography that can be applied by coating and developing a pattern by an EB lithography apparatus and developing it can also be applied. In this embodiment, an example of imprint lithography will be described.

  FIG. 5 is an explanatory diagram showing a line and space pattern formation process by imprint lithography. First, the resin material 11 is disposed on the quartz glass substrate 4 (a), heated to a temperature higher than the glass transition temperature of the resin material 11, the mold 14 is pressed against the resin material 11 at a high pressure, and the shape of the mold 14 is changed to the resin material. (B). Next, the mold 14 is cooled to a temperature lower than the glass transition temperature of the resin material 11 to separate the mold 14 from the resin material 11 (c). Finally, dry etching is performed until the film of the resin material 11 remaining in the space portion of the pattern disappears, thereby completing the line and space pattern (d).

  EB lithography is very time consuming to draw a large area, whereas imprint lithography can form a pattern in a very short time. Can be manufactured.

  In addition, there are EB steppers, extreme ultraviolet and vacuum ultraviolet steppers, X-ray steppers, and the like as a method for forming a line and space pattern with a fine period in a short time. It will be expensive. On the other hand, the imprint lithography has a very simple apparatus configuration, and the equipment cost and operation cost can be kept very low.

  Furthermore, by using transparent resin or glass that can be shaped by imprint lithography, grooves with a fine period can be formed directly by imprint lithography, greatly simplifying the manufacturing process and reducing manufacturing costs. A waveplate can be produced.

  In the present embodiment, nanoimprint lithography is employed as imprint lithography in which the resin material 11 is heated to a glass transition temperature or higher, the mold 14 is pressed at a high pressure, and the shape of the mold 14 is transferred to the resin. A step-and-flash imprint lithography may be performed in which a UV curable resin is poured between the substrate 4 and the mold 14 and the resin is cured by UV irradiation to transfer the shape.

  In the present embodiment, the regions A and B are divided in the vertical direction as shown in FIG. 1, but even if the regions A and B are divided in the horizontal direction as shown in FIG. 6, they are in a checkered pattern as shown in FIG. What was divided | segmented or what was divided | segmented into what kind of shape may be sufficient, and it can manufacture with the manufacturing method mentioned above.

  Another embodiment will be described.

  The wave plate 1 of the present embodiment is also formed with a fine periodic structure and is the optical axis of light transmitted on the same substrate 4 as the wave plate 1 of the embodiment of FIGS. It is common to form the fine periodic structure directly on the substrate 4 so that two regions different from each other (also described in this embodiment as being provided with regions A and B) are alternately arranged. It is. In the following description, members common to the wave plate 1 described above with reference to FIGS. 1 to 7 are the same as described above, and detailed description thereof is omitted. The plan view of the wave plate 1 of this embodiment is also the same as that of FIG. 1, FIG. 6, and FIG.

  In this embodiment, cross-sectional views of the groove 2 formed in each of the regions A and B with a fine period are shown in FIGS. FIG. 8 shows an example in which the width of the groove 2 gradually increases as it approaches the inlet of the groove 2 at the inlet side portion of the groove 2. When the groove 2 has the shape shown in FIG. 8, the refractive index near the surface of the wave plate 1 can be changed gently when the refractive index changes in the light incident direction. Reflection on the plate surface can be suppressed.

  FIG. 9 shows an example in which the width of the groove 2 is gradually narrowed toward the bottom at the bottom side portion of the groove 2. When the shape of the groove 2 shown in FIG. 9 is used, the refractive index at the bottom of the fine periodic structure can be configured to change gently when the refractive index changes in the light incident direction. Reflection at the bottom of the fine periodic structure can be suppressed.

  Further, as shown in the cross-sectional view of FIG. 10, the width of the groove 2 gradually increases as it approaches the inlet of the groove 2 at the inlet side portion of the groove 2, and the bottom side portion of the groove 2 It is possible to further reduce reflection by forming the groove 2 so as to gradually narrow toward the bottom.

  The manufacturing method of the wave plate 1 in which the shape of the groove 2 is as shown in FIGS. 8 to 10 can be the same as the manufacturing method of the wave plate 1 described in the above embodiment. Also, this can be directly manufactured by imprint lithography as in the case of the above-described embodiment.

  Another embodiment will be described.

  The present embodiment is a stereoscopic image display apparatus including the wave plate 1 having any one of the above-described configurations. FIG. 11 is an explanatory diagram illustrating the configuration of the stereoscopic image display device 51 of the present embodiment. The stereoscopic image display device 51 according to the present embodiment includes a liquid crystal display device 52, the above-described wave plate 1, and a normal quarter wave plate 53. FIG. 11 shows only one pixel of each of the left eye pixel 54 and the right eye pixel 55.

  In all pixels, the left-eye region of the wave plate 1 is configured to overlap the left-eye pixel 54 of the liquid crystal display device 52, and the right-eye region overlaps the right-eye pixel 55. For example, one of the aforementioned regions A and B is the left eye region of the wave plate 1 and the other is the right eye region. A left-eye image for viewing a stereoscopic image is displayed on each left-eye pixel 54 of the liquid crystal display device 52, and a right-eye image for viewing a stereoscopic image is displayed on each right-eye pixel 55. Further, the transmission axis of the analyzer 56 of the liquid crystal display device 52 and the optical axis of one region A or B of the wave plate 1 form an angle of + 45 °, and the optical of the other region B or A of the wave plate 1 is formed. It is arranged so as to form an angle of −45 ° with respect to the axis, and a normal quarter wavelength plate 53 is disposed thereon, and the optical axis is the transmission axis of the analyzer 56 of the liquid crystal display device 52 and the optical axis of the wavelength plate 1. They are arranged to form an angle of + 45 °.

  The normal liquid crystal display device 52 finally transmits the same analyzer (polarizing plate) 56 in all pixels, and the light from each pixel is linearly polarized light having the same polarization direction. Next, light from each pixel of the liquid crystal display device 52 passes through the wave plate 1 and becomes circularly polarized light or elliptically polarized light. At this time, the polarization rotation direction is opposite between the light transmitted through the left eye region (region A or B) of the wave plate 1 and the light transmitted through the right eye region (region B or A). When the light transmitted through each region of the wave plate 1 is transmitted through a normal quarter wave plate (wave plate having no optical axis different region) 53, all of the light is linearly polarized, but the left eye region of the wave plate 1 The direction of polarization differs between the light transmitted through and the light transmitted through the right eye region. As in the polarizing glasses 57 shown in FIG. 11, the transmission axis differs by 90 ° between the left eye and the right eye, and the light from the left eye pixel 54 of the stereoscopic image display device 51 is transmitted through the wave plate 1, the normal 1 The light from the right-eye pixel passes through the wave plate 1 and the normal quarter wave plate 53 so that the polarization direction of the linearly polarized light that has passed through the quarter wave plate 53 coincides with the transmission axis. When the polarizing glasses 57 on which the polarizing plates 61 are arranged so that the polarization direction of the linearly polarized light emitted through and the transmission axis coincide with each other and the image displayed on the stereoscopic image display device 51 is observed, The light from the pixel does not reach the right eye of the observer and reaches only the left eye, and the light from the pixel for the right eye does not reach the left eye of the observer and reaches only the right eye. Therefore, by displaying a parallax image (a left-eye image for the left-eye pixel and a right-eye image for the right-eye pixel) on the liquid crystal display device 52, the observer can observe a stereoscopic image.

  In the present embodiment, the normal quarter wavelength plate 53 is disposed on the stereoscopic image display device 51, but may be disposed on the polarizing glasses 57.

  The division of the region for the left eye and the right eye of the wave plate 1 used in the present embodiment can be performed in various ways such as the example described with reference to FIG. 1, FIG. 6, and FIG. However, the division of the areas A and B of the wave plate 1 and the areas of the left-eye pixel and the right-eye pixel of the liquid crystal display device 52 need to match.

It is a top view of the waveplate which is one embodiment of the present invention. It is an expanded longitudinal cross-sectional view of the groove | channel of a wavelength plate. It is a perspective view of the fine periodic structure which arranged the flat plate with the period sufficiently smaller than the wavelength of light. It is explanatory drawing which shows the process of forming the groove | channel of a fine periodic structure in the board | substrate made from quartz glass. It is explanatory drawing which shows the line and space pattern formation process by imprint lithography. It is a top view explaining the other structural example of a wavelength plate. It is a top view explaining the other structural example of a wavelength plate. It is explanatory drawing which shows the other structural example of the groove | channel of a fine periodic structure. It is explanatory drawing which shows the other structural example of the groove | channel of a fine periodic structure. It is explanatory drawing which shows the other structural example of the groove | channel of a fine periodic structure. It is explanatory drawing of the stereo image display apparatus which is one embodiment of this invention. It is explanatory drawing explaining the manufacturing process of the conventional wavelength plate. It is explanatory drawing explaining the manufacturing process of the conventional wavelength plate. It is explanatory drawing explaining the manufacturing process of the conventional wavelength plate. It is explanatory drawing of a structure of the conventional stereoscopic display apparatus. It is explanatory drawing which shows arrangement | positioning of a wave plate, a polarizing film, and an oriented film in the three-dimensional display apparatus shown in FIG.

Explanation of symbols

1 Wave plate 2 Groove 4 Substrate A, B area

Claims (9)

In a wave plate that changes the polarization state of light,
A substrate,
A fine periodic structure directly formed on the substrate;
With
In the fine periodic structure, two regions in which the directions of optical axes of transmitted light are different from each other are alternately formed.   2. The wave plate according to claim 1, wherein optical axes of the respective regions are orthogonal to each other, and a phase difference in each of the regions is ¼ of the wavelength of the light.   The wavelength plate according to claim 1, wherein the fine periodic structure is a groove formed on the substrate with a fine period.   The wave plate according to any one of claims 1 to 3, wherein the width of the groove gradually increases as it approaches the entrance of the groove at the entrance side portion of the groove.   The wave plate according to any one of claims 1 to 4, wherein a width of the groove gradually decreases toward a bottom portion at a bottom side portion of the groove. Each left-eye pixel displays a left-eye image for viewing a stereoscopic image, and each right-eye pixel displays a right-eye image for viewing a stereoscopic image;
An analyzer that converts the light from each pixel into linearly polarized light having the same polarization direction;
The wavelength plate according to any one of claims 1 to 5, wherein one of regions having different optical axis directions is overlapped with the left eye pixel and the other is overlapped with the right eye pixel. A wave plate that transmits light;
A stereoscopic image display device comprising: In the method of manufacturing a wave plate for manufacturing a wave plate that changes the polarization state of light,
Directly forming a fine periodic structure on the same substrate so that two regions in which the directions of optical axes of light transmitted through the fine periodic structure are different from each other are alternated,
Each of the regions is formed at a time by forming an etching mask on the substrate and performing dry etching.
A method for manufacturing a wave plate, wherein:   The etching mask is formed by performing lithography on the substrate to form a metal film, or forming a metal film on the substrate and performing lithography to etch, and the lithography is imprint lithography. The method for producing a wave plate according to claim 7, wherein the wave plate is provided. 9. The method of manufacturing a wave plate according to claim 8, wherein grooves are directly formed in the substrate with a fine period by the imprint lithography.

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