JP2012098657A - Retardation plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a retardation plate capable of emitting even such light as entering obliquely without being deviated from a desired phase difference as much as possible.SOLUTION: This retardation plate includes: a light-transmissive retardation substrate 4A that comprises first regions and second regions disposed alternately, and micro periodic structure parts 10A and 10B, on the first regions and the second regions respectively, that are alternately disposed with plate-like groove parts 11 and plate-like non-groove parts 12 continuously at a pitch shorter than the half wavelength of the incident light; and a phase difference compensating substrate 5A disposed in the light incident side of the retardation substrate 4A and having a negative C plate characteristic.

Description

  The present invention relates to a phase difference plate that changes a phase state of light.

  In a three-dimensional display device, for example, a right-eye image and a left-eye image projected on different pixels of a liquid crystal panel are emitted as different polarization states by a phase difference plate. The viewer recognizes the three-dimensional image by viewing the right-eye image with the right eye and the left-eye image with the left eye using polarized glasses having different absorption axes on the left and right.

  As the retardation plate, a retardation plate having a different phase difference in a pixel size region, that is, a patterned plate is used. Examples of the retardation plate capable of such patterning include those using a photo-alignment film and a liquid crystal polymer, and those using structural birefringence.

As a retardation plate using conventional structural birefringence, the one disclosed in Patent Document 1 has been proposed. As shown in FIG. 12, the retardation film 100 is made of a light transmissive material. The phase difference plate 100 is provided with first fine periodic structure portions A (A ₁ , A ₂ ˜) and second fine periodic structure portions B (B ₁ , B ₂ ˜) alternately and continuously. As shown in FIGS. 13 and 14, each of the fine periodic structure portions A and B has a pitch sufficiently shorter than a half wavelength of incident light, and plate-like groove portions 101 and plate-like portions 102 that are plate-like non-groove portions are alternately arranged. Are arranged in succession. In the first fine periodic structure portion A and the second fine periodic structure portion B, the arrangement direction of the plate-like groove portion 101 and the flat plate portion 102 is set in a direction rotated by 90 degrees.

  Birefringence characteristics are generated by periodically arranging the plate-like groove portions 101 (refractive index of air) and the flat plate portions 102 (refractive index of the substrate material) having different refractive indexes. The optical direction of the birefringence characteristic is determined by the arrangement direction of the plate groove portion 101 and the flat plate portion 102. Utilizing such characteristics, the retardation plate 100 changes the right-eye video and the left-eye video to light having different polarization states.

JP 2006-30461 A

  However, the conventional retardation plate 100 using structural birefringence is configured to simply give birefringence to incident light. In addition to the light incident on the surface of the phase difference plate 100 in the direction perpendicular to the surface of the phase difference plate 100, the light incident on the phase difference plate 100 also includes light incident from an oblique direction. This obliquely incident light has a longer optical path length through the first fine periodic structure portion A and the second fine periodic structure portion B than the vertically incident light, and is emitted as light deviated from a desired phase difference. To do. Then, unnecessary light leaks from the subsequent polarizing plate, which may cause overlapping of the right-eye and left-eye images.

  Therefore, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a phase difference plate that can emit light that is incident obliquely without shifting as much as possible from a desired phase difference. .

  The present invention is light transmissive and is incident on at least one of the first region (S1) and the second region (S2) alternately arranged, and the first region (S1) and the second region (S2). Fine periodic structure portions (10A), (10B), and (14) in which plate-like groove portions (11) and plate-like non-groove portions (12) are alternately and continuously arranged at a pitch shorter than a half wavelength of light. The phase difference substrate (4A), (4B) having the phase difference substrate (4A), and the phase difference substrate (4A), (4B) disposed on one of the light incident side and the light emission side, and having a negative C plate characteristic Compensation substrates (5A) and (5B) are provided.

  The fine periodic structure portions (10A) and (19B) are provided in the first region (S1) and the second region (S2) together with the fine periodic structure portion (10A) in the first region (S1). The fine periodic structure portion (10B) in the second region (S2) is set to a direction rotated by 90 degrees relative to each other, and the fine periodic structure portion (10A) in the first region (S1) It is preferable to provide a non-groove region portion (S3) in which no groove is formed between the fine periodic structure portions (10B) in the second region (S2).

  The retardation compensation substrate (5A) has at least regions corresponding to both the fine periodic structure portion (10A) in the first region (S1) and the fine periodic structure portion (10B) in the second region (S2). It is preferable to form so as to have negative C plate characteristics.

  Each of the fine periodic structure portions (10A) and (10B) includes a configuration in which the phase of each incident light is emitted by being shifted by a quarter wavelength.

  It is preferable that the retardation compensation substrate (5A) has a light shielding portion (6) made of a light absorbing material at a position corresponding to at least the non-groove region portion (S3).

  The width of the light shielding portion (6) is P2 + (t, where P2 is the width of the non-groove region portion (S3), t is the depth of the non-groove region portion (S3), and F is the F value of the optical system. / F).

  The fine periodic structure portion (14) is provided only in one of the first region (S1) and the second region (S2), and in the region (S1) where the fine periodic structure portion (14) is provided. In the region (S2) where the phase of the incident light is emitted with a shift of ½ wavelength and the fine periodic structure portion (14) is not provided, the phase of the incident light is emitted without being shifted. .

  The phase difference compensation substrate (5B) has a structure corresponding to the region (S1) provided with the fine periodic structure portion (14) in the birefringent portion (5a) having a negative C plate characteristic. A region corresponding to the region (S2) where the portion (14) is not provided is preferably formed in the non-birefringent portion (5B).

  It is preferable that the retardation compensation substrate (5B) has a light shielding portion (6) made of a light absorbing material at a position corresponding to a boundary portion between the first region (S1) and the second region (S2).

  The width of the light shielding part (6) is preferably t / F, where t is the depth of the plate groove and F is the F value of the optical system.

  According to the present invention, when light is incident obliquely on the phase difference plate, a large phase difference shift occurs as the angle of oblique incidence increases with reference to the desired phase difference when passing through the phase difference substrate. When the substrate passes, the opposite phase difference (phase difference in the orthogonal direction) becomes larger, so that the phase difference deviation is canceled as much as possible. Therefore, it is possible to provide a phase difference plate that can emit light that is incident obliquely without shifting as much as possible from a desired phase difference.

BRIEF DESCRIPTION OF THE DRAWINGS It is 1st Embodiment of this invention and is a principal part schematic block diagram of a three-dimensional display apparatus. FIG. 1 is a configuration diagram of a phase difference plate according to a first embodiment of the present invention. 1A and 1B show a first embodiment of the present invention, in which FIG. 1A is a partial plan view of a retardation substrate, and FIG. FIG. 3 is a diagram illustrating the first embodiment of the present invention, in which the phase difference characteristic of the phase difference compensation substrate is modeled as an ellipsoid as a relationship of refractive index anisotropy. FIG. 6 is a schematic configuration diagram of a main part of a three-dimensional display device according to a second embodiment of the present invention. FIG. 5 is a configuration diagram of a retardation plate showing a second embodiment of the present invention. FIG. 2 shows a second embodiment of the present invention, in which (a) is a partial plan view of a retardation substrate, and (b) is a partial perspective view of the retardation substrate. The matching conditions of the phase difference substrate and the phase difference compensation substrate will be described. (A) is a perspective view of the phase difference substrate, (b) is a perspective view of the phase difference compensation substrate, and (c) is a refractive index of the phase difference compensation substrate. It is the figure which modeled the relationship of anisotropy into the ellipsoid. It is a characteristic diagram which shows the angle | corner phase difference variation of a phase difference board | substrate and a phase difference compensation board | substrate with respect to the incident angle of incident light. It is a figure which shows the structure of the phase difference board in the case of applying this invention to a three-dimensional imaging device. It is a figure which shows the structure of the phase difference board in the case of applying this invention to a three-dimensional imaging device. It is. It is a whole top view of a phase difference plate which shows a conventional example. It is a partial expanded sectional view of a phase difference plate which shows a conventional example. It is an enlarged perspective view of a fine periodic structure portion of a phase difference plate, showing a conventional example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
1 to 4 show a first embodiment in which a phase difference plate according to the present invention is applied to a three-dimensional display device. In FIG. 1, a three-dimensional display device 1A has a liquid crystal panel 2 that is a video display element. In the liquid crystal panel 2, pixels for the right eye and the left eye are alternately arranged, for example, for each horizontal line. The right-eye image light is emitted from each right-eye pixel, and the left-eye image light is emitted from the left-eye pixel. Each emitted light is linearly polarized light having the same vibration direction.

  The phase difference plate 3 </ b> A is disposed on the light emission side of the liquid crystal panel 2. As shown in FIG. 2, the phase difference plate 3 </ b> A includes a phase difference substrate 4 </ b> A and a phase difference compensation substrate 5 </ b> A. As shown in detail in FIGS. 3A and 3B, the phase difference substrate 4A is made of polycarbonate, vinyl chloride, polyester, polyimide, polyolefin, or acrylic transparent resin. Yes. On the phase difference substrate 4A, first regions S1 and second regions S2 having dimensions matching the pixel size of the liquid crystal panel 2 are alternately and continuously provided. The first region S1 is provided with a first fine periodic structure portion 10A in which plate-like groove portions 11 and plate-like non-groove portions 12 are alternately and continuously arranged at a pitch shorter than ½ wavelength of incident light. . The second region S2 is also provided with the second fine periodic structure portion 10B in which the plate-like groove portions 11 and the plate-like non-groove portions 12 are alternately and continuously arranged at a pitch shorter than ½ wavelength of the incident light. . Each plate-like groove 11 is a groove that opens only on the upper surface of the retardation substrate 4A, and is formed by a groove whose inner peripheral surface is closed. Thereby, each plate-shaped non-groove part 12 is connected by the peripheral non-groove part 13.

  The first fine periodic structure portion 10A and the second fine periodic structure portion 10B cause structural birefringence due to the periodic structures of the plate-like groove portion 11 and the plate-like non-groove portion 12, respectively. Using this structural birefringence, the first fine periodic structure portion 10A is set to a region where a + λ / 4 phase difference is generated, for example, and the second fine periodic structure portion 10B is set to a region where a -λ / 4 phase difference is generated, for example. Has been. That is, the phase difference substrate 4A is configured as a ± 1/4 wavelength plate in which + λ / 4 regions and −λ / 4 regions are alternately arranged. The reason why the phase difference of light passing through the fine periodic structure can be set to a desired wavelength will be described below.

  In the first fine periodic structure portion 10A and the second fine periodic structure portion 10B, the arrangement direction of the plate-like groove portion 11 and the plate-like non-groove portion 12 becomes a slow axis, and the arrangement direction of the plate-like groove portion 11 and the plate-like non-groove portion 12 The 90-degree rotation direction is the fast axis. In the first fine periodic structure portion 10A and the second fine periodic structure portion 10B, the slow axis direction and the fast axis direction are set to directions rotated by 45 degrees with respect to the vibration direction of the linearly polarized light that is the incident light. In addition, in the first fine periodic structure portion 10A and the second fine periodic structure portion 10B, the arrangement direction of the plate-like groove portion 11 and the plate-like non-groove portion 12 is set to a direction rotated by 90 degrees with respect to each other. The directions of the axes are directions rotated by 90 degrees with respect to each other.

  Between the first fine periodic structure portion 10A and the second fine periodic structure portion 10B, a non-groove region portion S3 in which no groove is formed is provided.

  As shown in FIG. 2, the phase difference compensation substrate 5A is made of a light transmissive material. The phase difference compensation substrate 5A is formed so that the entire region has a negative C plate characteristic. That is, there is no refractive index anisotropy in the surface direction of the surface of the retardation compensation substrate 5A, there is a refractive index anisotropy in the direction perpendicular to the surface direction, and the refractive index in the direction perpendicular to the surface direction refractive index. Is small.

  A light shielding portion 6 made of a light absorbing material is provided on one surface of the retardation compensation substrate 5A. The light shielding unit 6 is in close contact with the light incident side of the retardation substrate 4A. The light shielding portion 6 is a pattern corresponding to the non-groove region portion S3 of the retardation substrate 4A, and is disposed at a position corresponding to the non-groove region portion S3.

  The width W1 of the light shielding portion 6 is W1 = P2 + (t / F), where P2 is the width of the non-groove region portion S3, t is the depth of the non-groove region portion S3, and F is the F value of the optical system (lens). Is set to

  Here, F = f (focal length) / φ (aperture), and φ / 2 = f / 2F. If f → t, then φ / 2 = t / 2F and φ = t / F.

  The phase difference compensation substrate 5A is formed of a TAC (triacetylcellulose) film and a film using a structural birefringence by laminating a dielectric film having a film thickness sufficiently shorter than a wavelength and having a difference in refractive index. For example, a horizontally aligned liquid crystal polymer and an A plate material such as a stretched film face each other with the slow axes orthogonal to each other with the same phase difference.

  Next, the reason why each region of the phase difference substrate 4A can be set to a desired phase difference will be described.

The refractive indexes N _TM and N _TE effective in the direction in which the plate-like groove portion 11 and the plate-like non-groove portion 12 extend and in the direction orthogonal thereto are determined from the refractive index and the periodic structure of the plate-like groove portion 11, and Can be sought. Here, TM and TE represent components in a direction of ± 45 degrees with respect to the vibration direction of linearly polarized light. The refractive index of the plate-like groove portion 11 is N ₁ , and the refractive index of the plate-like non-groove portion 12 is N ₂ . Since the medium of the plate-like groove 11 is air, N ₁ = 1. The width of the plate-like groove portion 11 is L, the width of the plate-like non-groove portion 12 is S, and the depth of the first and second fine periodic structure portions 10A and 10B (the plate-like groove portion 11 and the plate-like non-groove portion 12) is d. . The filling factor f is f = L / P (pitch P = L + S).

N _TM = {f · N ₂ ² + (1−f)} ^1/2
N _TE = [N ₂ ² / {f + (1−f) N ₂ ² }] ^1/2
From the above equation, the phase difference δ given to the emitted light is obtained by δ = (N _TM −N _TE ) × d. Therefore, the phase difference δ can be controlled by the refractive index N ₂ of the phase difference substrate 4A and the depth d of the fine periodic structure portions 10A and 10B. In this first embodiment, the + λ / 4 region and the −λ / 4 region are alternated. It is constituted as a ± 1/4 wavelength plate repeated.

  If an alignment pattern portion is formed in addition to the light shielding portion 6 on the phase difference compensation substrate 5A, it can be fixed to the phase difference substrate 4A at an accurate position. The phase difference compensation substrate 5A and the phase difference substrate 4A are fixed at positions outside the plate-like groove portion 11 and the plate-like non-groove portion 12 with a thermosetting or ultraviolet curable adhesive or the like.

  Returning to FIG. 1, the operation of the three-dimensional display device 1A will be described next. The right-eye image is displayed on the right-eye pixel of the liquid crystal panel 2, and the left-eye image is displayed on the left-eye pixel of the liquid crystal panel 2. When the linearly polarized light of the right-eye image passes through the phase difference plate 3A, the polarization state is changed and emitted as, for example, right circularly polarized light. When the linearly polarized light of the left-eye image passes through the phase difference plate 3A, the polarization state is changed, and is emitted as, for example, left circularly polarized light.

  As shown in FIG. 1, a circularly polarizing plate 15a that transmits right-circularly polarized light is provided on the right-eye lens side, and glasses 15 each having circularly polarizing plate 15b that transmits left-circularly polarized light are viewed on the left-eye lens side. In the right eye, only the right eye image is visible, and in the left eye, only the left eye image is visible. As a result, the viewer can view the 3D video.

  Next, the polarization action of the phase difference plate 3A will be described in detail. When light is incident obliquely on the phase difference plate 3A, the optical path length passing through the phase difference substrate 4A is longer than the light incident in the vertical direction, and the optical path length is increased as the angle of the oblique incident light is increased. That is, as the incident light is tilted, the phase difference that develops increases.

  On the other hand, the phase difference compensation plate 5A has negative C plate characteristics. When an ellipsoid is modeled as a relationship of refractive index anisotropy, it is as shown in FIG. As shown in FIG. 4, as the angle of obliquely incident light increases, the refractive index decreases in the direction inclined, and there is no change in the refractive index in the perpendicular direction (non-inclined direction). Further, no extra phase difference is given to incident light in the vertical direction.

  Further, the retardation plate 3A is provided with a first fine periodic structure portion 10A and a second fine periodic structure portion 10B in which the arrangement directions of the plate-like groove portions 11 and the plate-like non-groove portions 12 are different from each other, but negative C Since the phase difference compensation substrate 5A having a plate characteristic has no refractive index anisotropy in the plane direction, both the phase difference deviations of the first fine periodic structure portion 10A and the second fine periodic structure portion 10B can be compensated.

  As described above, the incident light in the vertical direction without inclination is given a desired phase difference when passing through the phase difference substrate 4A, and no phase difference is given when passing through the phase difference compensation substrate 5A. Light with phase difference is emitted. Inclined obliquely incident light causes a large phase difference shift as the oblique incident angle increases with the desired phase difference as a reference when passing through the retardation substrate 4A. However, when passing through the phase difference compensation substrate 5A, the phase difference opposite to the above (phase difference in the orthogonal direction) becomes large, so that the phase difference deviation is canceled as much as possible. Therefore, even the light obliquely incident on the phase difference plate 3A is emitted without being shifted as much as possible from the desired phase difference.

  In each of the fine periodic structure portions 10A and 10B, plate-like groove portions 11 and plate-like non-groove portions 12 are alternately and continuously arranged, and the plate-like groove portions 11 are grooves whose inner peripheral surfaces are closed. Thus, each plate-like groove portion 11 is a groove whose inner peripheral surface is closed, and thereby each plate-like non-groove portion 12 is connected to each other by the surrounding non-groove portion 13. The non-groove portion 12 has a strong structure and is not easily deformed or broken by stress or external force.

  Between the first fine periodic structure portion 10A and the second fine periodic structure portion 10B, a non-groove region portion S3 in which no groove is formed is provided. Therefore, since the interval between the plate-like groove portion 11 of the first fine periodic structure portion 10A and the plate-like groove portion 11 of the second fine periodic structure portion 10B is widened, the strength of the phase difference substrate 4A is improved.

  The first and second fine periodic structure portions 10A and 10B are configured such that the phase of each incident light is emitted by being shifted by a quarter wavelength. Therefore, when linearly polarized light having the same vibration direction is incident light, circularly polarized light having different rotation directions can be emitted.

  The first and second fine periodic structure portions 10A and 10B are set in directions rotated by 45 degrees with respect to the vibration direction of linearly polarized light that is incident light. Therefore, the phase difference can be generated with the highest efficiency with respect to the incident light.

  The phase difference compensation substrate 5A has a light shielding portion 6 made of a light absorbing material at a position corresponding to the non-groove region portion S3 on the incident side of the phase difference substrate 4A. Therefore, light incident on the non-groove region portion S3 in the vertical direction can be reliably shielded. In addition, in this embodiment, the width W1 of the light-shielding portion 6 is set such that the width of the non-groove region portion S3 is P2, the depth of the non-groove region portion S3 is t, and the F value of the optical system (lens) is F. W1 = P2 + (t / F) is set. Therefore, as shown in FIG. 2, light entering obliquely across the non-groove region portion S3 from the first fine periodic structure portion 10A or the second fine periodic structure portion 10B can be blocked by the oblique incident light. Unnecessary light which is not given and becomes leaked light can be reliably shielded.

(Second Embodiment)
5 to 7 show a second embodiment in which the phase difference plate according to the present invention is applied to a three-dimensional display device. In FIG. 5, the three-dimensional display device 1B includes a liquid crystal panel 2 that is a video display element. In the liquid crystal panel 2, pixels for the right eye and the left eye are alternately arranged, for example, for each horizontal line. The right-eye image light is emitted from each right-eye pixel, and the left-eye image light is emitted from the left-eye pixel. Each emitted light is linearly polarized light having the same vibration direction.

  The phase difference plate 3 </ b> B is disposed on the light emission side of the liquid crystal panel 2. As shown in FIG. 6, the phase difference plate 3 </ b> B includes a phase difference substrate 4 </ b> B and a phase difference compensation substrate 5 </ b> B, and both the substrates 4 </ b> B and 5 </ b> B are arranged so as to overlap each other in the light emission direction of the liquid crystal panel 2.

  As shown in detail in FIGS. 7A and 7B, the phase difference substrate 4B is formed of a transparent resin such as polycarbonate, vinyl chloride, polyester, polyimide, polyolefin, and acrylic. The retardation substrate 4B is provided with first regions S1 and second regions S2 having dimensions corresponding to the pixel size of the liquid crystal panel 2 alternately and continuously. The first region S1 is provided with a fine periodic structure portion 14 in which plate-like groove portions 11 and plate-like non-groove portions 12 are alternately and continuously arranged at a pitch shorter than ½ wavelength of incident light. Unlike the first embodiment, no plate groove is provided in the second region S2.

  The fine periodic structure portion 14 generates structural birefringence due to the periodic structure of the plate-like groove portion 11 and the plate-like non-groove portion 12. The second region S2 does not cause structural birefringence. The phase difference substrate 4B is configured as a λ / 2 phase difference substrate in which λ / 2 regions and 0 regions are alternately arranged using structural birefringence.

  Each plate-like groove portion 11 of the fine periodic structure portion 14 is a groove that opens only on the upper surface of the phase difference substrate 4B, and is formed as a groove whose inner peripheral surface is closed. Thereby, each plate-shaped non-groove part 12 is connected by the peripheral non-groove part 13.

  In the fine periodic structure portion 14, the arrangement direction of the plate-like groove portions 11 and the plate-like non-groove portions 12 is a slow axis, and the 90 ° rotation direction of the arrangement direction is a fast axis. In the fine periodic structure section 14, the slow axis direction and the fast axis direction are set to directions rotated by 45 degrees with respect to the vibration direction of the linearly polarized light that is the emitted light.

  The phase difference compensation substrate 5B is made of a light transmissive material as shown in FIG. The phase difference compensation substrate 5B is a second region where the fine periodic structure portion 14 is not provided in the birefringent portion 5a having a negative C plate characteristic in the region corresponding to the first region S1 where the fine periodic structure portion 14 is provided. A region corresponding to S2 is formed in the non-birefringent portion 5b. That is, the second region S2 is a region that does not exhibit any birefringence characteristics.

  On one surface of the retardation compensation substrate 5, a light shielding portion 6 made of a light absorbing material is provided. The light shielding unit 6 is in close contact with the light incident side surface of the retardation substrate 4B. The light shielding unit 6 is a pattern corresponding to the boundary position between the first region S1 and the second region S2, and is disposed at a position corresponding to the boundary position. The width of the light-shielding portion 6 is set to W2, where the depth of the fine periodic structure portion 14 (plate-like groove portion 11 and plate-like non-groove portion 12) is t, and the focal length of the optical system is F, W2 = (t / F). Has been.

  Next, the operation of the three-dimensional display device 1B will be described. A right-eye image is displayed at each right-eye pixel of the liquid crystal panel 2, and a left-eye image is displayed at each left-eye pixel of the liquid crystal panel 2. When passing through the phase difference plate 3B, one of the linearly polarized light of the right-eye image and the linearly polarized light of the left-eye image is emitted as linearly polarized light that is rotated 90 degrees and rotated 90 degrees with respect to each other. The

  When the right eye lens side is viewed with the polarizing plate 16a that transmits one linearly polarized light and the left eye lens side with the polarizing plate 16b that transmits the other linearly polarized light, the right eye is for the right eye. Only the image is visible, and the left eye only sees the image for the left eye. As a result, the viewer can view the 3D video.

  Next, the polarization action of the phase difference plate 3B will be described in detail. The light passing through the second region of the phase difference substrate 4B where the fine periodic structure portion 14 is not provided and the non-birefringence portion 5b of the phase difference compensation substrate 5B is emitted in a state where no phase difference is given. On the other hand, the light passing through the fine periodic structure portion 14 (first region S1) of the phase difference substrate 4B and the birefringence portion 5a of the phase difference compensation substrate 5B has a similar effect as described in the first embodiment. Given the phase difference. Therefore, even the light obliquely incident on the phase difference plate 3B is emitted without being shifted as much as possible from the desired phase difference.

  In the fine periodic structure portion 14, plate-like groove portions 11 and plate-like non-groove portions 12 are alternately and continuously arranged, and the plate-like groove portions 11 are formed by grooves whose inner peripheral surfaces are closed. Thus, each plate-like groove portion 11 is a groove whose inner peripheral surface is closed, and thereby each plate-like non-groove portion 12 is connected to each other by the surrounding non-groove portion 13. The non-groove portion 12 has a strong structure and is not easily deformed or broken by stress or external force.

  The fine periodic structure unit 14 is configured such that the phase of incident light is emitted with a shift of ½ wavelength. Therefore, when linearly polarized light having the same vibration direction is incident light, it can be emitted as linearly polarized light rotated by 90 degrees.

  The fine periodic structure portion 14 is set in a direction rotated by 45 degrees with respect to the vibration direction of linearly polarized light that is incident light. Therefore, the phase difference can be generated with the highest efficiency with respect to the incident light.

  The phase difference compensation substrate 5B is on the incident surface side of the phase difference substrate 4B and at the boundary position between the fine periodic structure portion 14 and the second region S2 where the fine periodic structure is not formed, is a light shielding material made of a light absorbing material. Since the portion 6 is disposed, it is possible to shield light that is obliquely incident and passes across the fine periodic structure portion 14 and the second region S2 that is not the fine periodic structure. In particular, in this embodiment, the width W2 of the light shielding portion 6 is such that the depth of the fine periodic structure portion 14 (plate-like groove portion 11 and plate-like non-groove portion 12) is t, and the F value of the optical system (lens) is F. , T / F. Therefore, as shown in FIG. 6, it is possible to reliably block light passing through the fine periodic structure portion 14 and the second region S2 where the fine periodic structure is not formed by obliquely incident light. Therefore, it is possible to reliably shield unnecessary light that becomes leakage light.

(Matching condition between phase difference substrate and phase difference compensation substrate)
Next, the phase difference matching condition between the phase difference substrate 4A and the phase difference compensation substrate 5A will be described using the phase difference plate 3A of the first embodiment as an example.

First, a phase difference change amount δ1 of the phase difference substrate 4A in obliquely incident light is obtained. In FIG. 8A, assuming that the refractive indexes orthogonal to each other in the surface direction of the surface of the retardation substrate 4A are N1 and N2 (N2 <N1), the refractive index difference ΔN _a is
ΔN _a = N1-N2.

When the depth of the fine periodic structures 10A and 10B of the phase difference substrate 4A is d1, and the inclination angle of incident light is θ, the phase difference variation δ1 of the phase difference substrate 4A is
δ1 = ΔN _a · d1 (1-1 / cos θ).

Here, it is varied inclination angle of the incident light θ is, the refractive index difference .DELTA.N _a does not change. The filling factor f changes in refractive index with the line width L and pitch P, but even if the inclination angle θ changes, both the line width L and pitch P only change by 1 / cos θ. It does not change.

  Accordingly, the phase difference change amount δ1 of the phase difference substrate 4A changes only by the optical path length.

Next, the phase difference variation δ2 of the phase difference compensation substrate 5A in the oblique incident light is obtained. In FIG. 8B, when the refractive index in the surface direction of the surface of the retardation compensation substrate 5A is N3, the refractive index in the direction orthogonal to the surface direction is N4 (N4 <N3), and the inclination angle of incident light is θ, The refractive index difference ΔN _b is ΔN _b = {(N3 · cos θ) ² + (N4 · cos θ) ² } ^1/2 from the coordinates of the ellipse (see FIG. 8C).

When the depth (plate thickness) of the phase difference compensation substrate 5A is d2, the phase difference change amount δ2 of the phase difference compensation substrate 5A is:
δ2 = ΔN _b · d2 / cos θ.

Here, when the inclination angle θ of the incident light changes, the refractive index difference ΔN _b changes, and the optical path length also changes. Accordingly, the phase difference variation δ2 of the phase difference compensation substrate 5A varies depending on the refractive index difference ΔN _b and the optical path length. As described above, matching can be achieved by adjusting the refractive index difference ΔN _b and the depth (plate thickness) d2 of the retardation compensation substrate 5.

  For example, assuming that the values of the phase difference substrate 4A and the phase difference compensation substrate 5A are as shown in Table 1 below, the phase difference variation amounts δ1 and δ2 with respect to the inclination angle θ of the incident angle are as shown in Table 2 below.

  Respective phase difference variation amounts δ1 and δ2 with respect to the tilt angle θ of the incident light are characteristic diagrams as shown in FIG. 9, and even if the light is obliquely incident on the phase difference plate 3A, the desired phase difference (± λ / 4).

(Modifications etc.)
In each of the embodiments described above, the phase difference compensation substrates 5A and 5B are arranged on the incident surface side of the phase difference substrates 4A and 4B, but may be arranged on the emission surface side.

  In the first embodiment, the retardation substrates 4A and 4B are alternately configured with + λ / 4 regions and −λ / 4 regions having a fine periodic structure. However, the present invention is not limited to this. A difference region can be configured.

  In the first embodiment, the retardation compensation substrate 5A is formed in a birefringent structure having a negative C-plate characteristic in the entire region, but the first fine periodic structure portion 10A and the second region S2 in the first region S1. The regions corresponding to both of the second fine periodic structure portions 10B may be formed in a birefringent structure having at least negative C plate characteristics.

  In the second embodiment, the retardation substrate 4B is configured by alternately arranging λ / 2 regions having a fine periodic structure and zero regions having no phase difference, but the present invention is not limited to this, and various wavelength difference regions are formed depending on the fine periodic structure. Can be configured.

  In each of the above embodiments, the application of the present invention to the three-dimensional display device has been described. However, application to a three-dimensional imaging device is also possible. The phase difference substrates 4A and 4B have a configuration in which + λ / 4 and −λ / 4 regions S1 and S2 are alternately repeated as shown in FIG. 10, and λ / 2 and 0 regions are alternately shown in FIG. Use one that repeats. The phase difference compensation substrate has a negative C plate characteristic with respect to the entire range of ± λ / 4, a negative C plate characteristic in the region of λ / 2, and no birefringence in the region of 0. Use one that does not have That is, it is only necessary that the relationship between the polarization state and the incident / exit is opposite to that of the three-dimensional display device.

  For example, the image lights corresponding to the left and right eyes are incident on the phase difference substrates 4A and 4B as circularly polarized light having different rotation directions as shown in FIG. 10 or linearly polarized light whose axes are rotated by 90 degrees as shown in FIG. To do. The light passes through regions corresponding to the left and right eyes of the phase difference substrates 4A and 4B, and is emitted as linearly polarized light having different axis directions for the regions S1 and S2. Then, by passing through the polarizing plate, only the linearly polarized light of the image for the left eye is emitted in one region, and only the linearly polarized light of the image for the right eye is emitted in another region. Even light obliquely incident on the phase difference plate is emitted without being shifted as much as possible from the desired phase difference by the compensation function of the phase difference compensation substrate.

2 Liquid crystal panel (display element)
3A, 3B Phase difference plate 4A, 4B Phase difference substrate 5A, 5B Phase difference compensation substrate 5a Birefringence part 5b Non-birefringence part 6 Light shielding part 10A First fine periodic structure part 10B Second fine periodic structure part 11 Plate-like groove part 12 Plate-like non-groove part 14 Fine periodic structure part S1 1st area | region S2 2nd area | region S3 Non-groove area | region part

Claims (10)

At least one of the first region and the second region, and the first region and the second region, which are alternately arranged with light transmission, and a plate-like groove portion and a plate shape with a pitch shorter than ½ wavelength of incident light. A phase difference substrate having fine periodic structure portions in which non-groove portions are alternately and continuously arranged, and
A phase difference plate, comprising: a phase difference compensation substrate having a negative C plate characteristic, which is disposed on one of the light incident side and the light emission side of the phase difference substrate. The phase difference plate according to claim 1,
The fine periodic structure portion is provided in both the first region and the second region, and the fine periodic structure portion in the first region and the fine periodic structure portion in the second region have an arrangement direction of 90 with respect to each other. Set to the direction of rotation,
A phase difference plate, wherein a non-groove region portion in which no groove is formed is provided between the fine periodic structure portion in the first region and the fine periodic structure portion in the second region. The phase difference plate according to claim 1 or 2,
The retardation compensation substrate is formed so that regions corresponding to both the fine periodic structure portion in the first region and the fine periodic structure portion in the second region have at least negative C plate characteristics. Retardation plate. The phase difference plate according to claim 2 or 3,
Each of the fine periodic structures is configured so that the phase of each incident light is emitted with a phase shift of ¼ wavelength. The retardation plate according to claim 3 or 4, wherein:
The retardation plate has a light shielding portion made of a light absorbing material at a position corresponding to at least the non-groove region portion. The phase difference plate according to claim 5,
The width of the light shielding portion is P2 + (t / F), where P2 is the width of the non-groove region portion, t is the depth of the non-groove region portion, and F is the F value of the optical system. Retardation plate. The phase difference plate according to claim 1,
The fine periodic structure portion is provided only in one of the first region and the second region,
In the region where the fine periodic structure portion is provided, the phase of the incident light is emitted with a shift of ½ wavelength, and in the region where the fine periodic structure portion is not provided, the phase of the incident light is not shifted. The phase difference plate is injected into The phase difference plate according to claim 7,
In the retardation compensation substrate, a region corresponding to the region where the fine periodic structure portion is provided has a negative C-plate characteristic, and a region corresponding to a region where the fine periodic structure portion is not provided is non-existent. A phase difference plate formed in a birefringent portion. The phase difference plate according to claim 7 or claim 8,
The retardation plate has a light shielding portion made of a light absorbing material at a position corresponding to a boundary portion between the first region and the second region. The phase difference plate according to claim 9,
The width of the light shielding part is t / F, where t is the depth of the plate-like groove part and F is the F value of the optical system.

Images