JP2005037745A - Polarized beam conversion element, its manufacturing method, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarized beam conversion element which can be manufactured with a simple process, whose manufacturing cost can be reduced, and also, which can attain a large surface. <P>SOLUTION: Inclined planes 11a and 11b facing each other while inclining in different directions are repeatedly and alternatively formed from the incident side surface 1A of a transparent base material 1(11 and 12) to the rear side 1B, and a polarized light separation film 2 is formed on the inclined planes 11a and 11b, and also, at least a quarter wavelength plate 3 and a reflection film 4 are arranged on the incident side surface 1A of the transparent base material 1 so as to be alternately positioned corresponding to a pair of adjacent inclined planes mutually facing in the opposite direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polarization beam conversion element that converts non-polarized light or the like into only one direction of a polarized light component, a method for manufacturing the same, and a liquid crystal display device.

  For example, in a liquid crystal panel display, backlight light is applied to the liquid crystal panel via a polarizing plate, and display is performed by turning on and off the transmitted light depending on the alignment state of the liquid crystal depending on whether or not an electric field is applied. . In such a liquid crystal panel, only light having a specific polarization direction that has been transmitted through the polarizing plate is used. Therefore, only 50% or less of the backlight light can be used for display. Therefore, in order to improve the brightness of the display screen, it is indispensable to increase the output of the backlight, resulting in an increase in power consumption. For this reason, for example, a backlight using a light guide plate that efficiently emits light from a light source in a surface direction has been proposed (see, for example, Non-Patent Documents 1 and 2).

Therefore, in order to improve the utilization efficiency of the backlight light, it has been studied to convert the polarization of the backlight light and use most of it, and a sheet-like polarizing element for a liquid crystal panel is disclosed (for example, (See Patent Documents 1 to 3.)
If these sheet-like polarizing elements are used, the non-polarized light from the backlight can be converted into linearly polarized light having a specific polarization direction, and as a result, the utilization efficiency of the light source can be dramatically increased, It is expected that low power consumption or high luminance will be achieved.

  As shown in FIG. 9, the structure of the plate-shaped polarizing element that is widely used at present is that the polarization separation film 102 is obliquely sandwiched between a transparent substrate 101 such as a highly transparent and high refractive index glass or a low refractive index glass. Then, the polarization separation films 102 are arranged at a constant pitch, and the half-wave plates 103 are arranged corresponding to every other polarization separation film 102 in accordance with the pitch of the polarization separation films 102. The one formed is typical. With respect to the plate-shaped polarizing element having such a structure, the mask 104 is interposed on the light incident side surface with a position corresponding to the arrangement position of the half-wave plate 103 so that light is transmitted only through the half-wave plate 103. Is provided.

  When light is introduced between the masks 104, for example, the P-polarized wave passes through the polarization separation film 102 as indicated by the solid line arrow P, and is converted into an S-polarized wave by the half-wave plate 103. One S-polarized wave is reflected by the polarization separation film 102 as indicated by a broken-line arrow S, and is derived from between the half-wave plates 103 as an S-polarized wave.

  By the way, in the plate-shaped polarizing element having the above structure, a polarizing separation film is formed on the surface of a large number of flat glass plates by vapor deposition or sputtering, and these glass plates are laminated and bonded to each other to adhere to the bonding surface. Then, the glass plate bonded in multiple layers is cut (sliced) so as to be at a predetermined angle (for example, 45 degrees), and the sliced both surfaces are mirror-polished. After this mirror polishing, a half-wave plate is attached at every other position corresponding to the pitch of the polarization separation film.

  However, since the plate-shaped polarizing element manufactured through such a process is manufactured through many steps, the manufacturing cost is increased. Examples of necessary steps in the above manufacturing process include, for example, glass mirror polishing, cleaning, polarization separation film formation, adhesive application, lamination fixing, temperature heating for adhesive curing, jig fixing for oblique slicing, wire Slicing with a saw, separation / washing from a jig, double-sided rough polishing, mirror polishing, grinding wheel cutting for shape forming, and the like. In addition, according to the above process, it is extremely difficult to produce a polarizing element having a large area.

The polarizing element structure for the purpose of polarization separation conversion includes polarization layer separation on a resin molded sheet in which right-angled triangular prisms are arranged in an array, in addition to the example of the laminated member provided with the polarization separation film obliquely described above. A device in which a film and a polarization modulator are formed has also been reported (see, for example, Patent Document 4).
In this example, a polarization separation film is formed on the slope of the right triangular triangular prism, and an optical thin film serving as a polarization modulator is formed on the vertical plane.

  However, in order to form a polarization separation film on the slope of a right triangular triangular prism and to form an optical thin film that serves as a polarization modulator on the vertical plane, it is particularly necessary to form a uniform film up to the vicinity of the right triangular bottom of the groove. It is extremely difficult due to the effect of the shadow on the side wall of the groove, and when mass production is considered, the yield is also reduced.

In addition, a polarization beam conversion element in which a material having an isotropic refractive index and a material having anisotropy are combined with a boundary surface provided on a cross-sectional triangle has been reported (see, for example, Patent Document 5).
However, in this case, since an anisotropic refractive index material is used, the cost is increased, and the alignment of the crystal axes is required, which may lead to a decrease in workability and a decrease in productivity in the manufacturing process. This is disadvantageous for mass production.
Akira Togashi, “New Trend of Injection Molding System”, Plastics, November 2001 issue, Industrial Research Committee, p12-17 Koji Oki, “Overview of the latest technology of backlight”, FLAT PANEL DISPLAY 2002, Techno Times, p218-223 JP-A-11-84129 JP-A-11-202108 JP-A-9-265010 JP-A-10-96815 JP 2000-221324 A

  The present invention has been proposed in view of such a conventional situation, and can be manufactured by a simple process, can suppress the manufacturing cost, and can easily manufacture a large-area one. An object is to provide an element.

  In order to achieve the above-described object, the polarization beam conversion element of the present invention is formed by alternately and repeatedly forming inclined surfaces facing each other with different inclination directions from the front surface to the back surface of the transparent substrate. A structure in which a film is formed, and at least a quarter-wave plate and a reflective film are disposed at every other position corresponding to a pair of adjacent slopes facing each other on the light incident side surface of the transparent substrate. To do.

  The method of manufacturing a polarization beam converting element according to the present invention includes a step of forming a polarization separation film on the slope of the first transparent member on which slopes facing each other with different slope directions are formed, and embedding the slope to embed the slope. 2 having a slope opposite to each other from the light incident side surface to the back surface by the step of forming the transparent member and the step of removing a part of each surface of the first and second transparent members until the slope is exposed. A transparent base material having a polarization separation film formed on the inclined surface is prepared, and at least one position on the light incident side surface of the transparent base material at every other position corresponding to a pair of adjacent inclined surfaces facing each other. A quarter-wave plate and a reflective film are formed.

  Furthermore, the liquid crystal display device according to the present invention uses the polarization beam conversion element according to the above-described configuration of the present invention as the polarization beam conversion element.

According to each polarization beam conversion element according to the above-described configuration of the present invention, it is possible to convert the light into linearly polarized light while maintaining the use efficiency of the light source, similarly to the polarization beam conversion element of the conventional configuration described in FIG.
That is, in the polarization beam converting element according to the above-described configuration of the present invention, the incident light passes between the reflective films and enters the polarization separation film provided on the slope. The quarter-wave plate and the reflection film are arranged every other pair corresponding to a pair of adjacent slopes facing each other. In other words, every other quarter-wave plate and the reflective film are provided so as to straddle the top of the inclined surface.

  For example, a case where the polarization separation film reflects S-polarized light will be described. The incident P-polarized wave passes through this polarization separation film while maintaining the polarization component, and is emitted to the other surface of the transparent substrate. On the other hand, the S-polarized component is reflected once by the polarization separation film, passes through the incident-side quarter-wave plate, is reflected by the reflection film, and passes through the quarter-wave plate again, and becomes the polarization separation film. Incident. At this time, the S-polarized wave passes through the quarter-wave plate twice, so that the phase of the ordinary light component and the extraordinary light component is shifted by ½ wavelength, and is converted into orthogonal P-polarized light and incident again on the polarization separation film Is done. The P-polarized wave passes through the polarization separation film and is emitted to the other surface of the transparent substrate. In this way, it is possible to obtain a polarization beam conversion element that can convert light into linearly polarized light while suppressing a decrease in the amount of light.

  These polarizing beam conversion elements of the present invention can be manufactured by a simple process by the above-described manufacturing method of the present invention, and the manufacturing cost can be suppressed and a large area can be manufactured. .

  In the manufacturing method of the polarization beam converting element according to the present invention, the first transparent member is provided with a slope facing the first transparent member, that is, the groove surface of the transparent member (glass substrate, highly transparent organic material substrate, etc.) having the opposite slope groove is sputtered. A polarization separation film is formed by vapor deposition or the like, and the second transparent member is embedded in the inclined groove. For example, the second transparent member can be formed so as to embed the slope by filling a light transmissive member such as a highly transparent photocurable resin (for example, a highly transparent organic material) and then curing by light irradiation.

  Accordingly, the polarization beam conversion element according to the configuration of the present invention is manufactured without using a machining process such as laminating adhesion, slicing, flat surface polishing, and mirror surface polishing. Can be suppressed. Also, the area can be easily increased.

  In addition, the polarization beam conversion element of the present invention employs opposed slopes to reduce the shadow effect phenomenon caused by the groove slope itself when forming a polarization separation film on the slope by vapor deposition or sputtering. It is possible to form a uniform film up to the bottom, avoid a decrease in yield in the manufacturing process, and manufacture with good productivity, thereby reducing costs.

  In addition, by using this to form a liquid crystal display device, size reduction and cost reduction can be achieved.

  According to the polarizing beam conversion element of the present invention, it can be manufactured by a simple process, and the manufacturing cost can be suppressed and the cost can be reduced.

  In addition, in the polarization beam conversion element of the present invention, when forming a lens array that collects incident light in a region where the quarter-wave plate and the reflective film are not formed, the incident light can be used efficiently, In addition, the configuration of an optical device such as a liquid crystal display device incorporating a polarization beam conversion element can be simplified and downsized.

  Furthermore, according to the method for manufacturing a polarized beam conversion element according to the present invention, it is possible to improve workability and productivity without requiring complicated machining.

  Therefore, by configuring the liquid crystal display device using the polarization beam conversion element according to the present invention, the cost can be reduced and the size can be reduced.

  Hereinafter, a polarization beam converting element to which the present invention is applied and a manufacturing method thereof will be described in detail with reference to the drawings. First, an embodiment of a polarized beam conversion element according to the configuration of the present invention will be described.

(1) First Embodiment FIG. 1 shows a configuration example of a polarization beam conversion element to which the present invention is applied. The polarizing beam converting element shown in FIG. 1 is composed of a transparent substrate 1 (11 and 12), and each transparent substrate 11 and 12 has opposing inclined surfaces 11a and 11b extending from the light incident side surface 1A to the back surface 1B. The polarization separation film 2 is formed on each of the inclined surfaces 11a and 11b. A quarter-wave plate 3 and a reflective film 4 are formed at every other position on the light incident side surface 1A corresponding to a pair of adjacent inclined surfaces 11a and 11b facing each other. .

  Although not shown, a lens array made of, for example, a light transmissive resin may be formed so as to cover the reflective film 4. When forming a lens array having the function of a condensing lens as described above, an optical device such as a liquid crystal display device that can efficiently collect incident light between the reflecting films 4 and incorporates a polarization beam conversion element. The configuration can be simplified and downsized.

  The transparent base materials 11 and 12 are made of, for example, a resin having a refractive index of 1.8, and have inclined surfaces 11a and 11b facing each other by forming a groove having a V-shaped cross section that forms approximately 45 ° with respect to the light incident surface 1A, for example. The angle at which the inclined surfaces 11a and 11b meet is approximately 90 °, and so-called triangular prisms having a right-angled triangular cross section are arranged so that the inclined surfaces overlap each other.

The transparent base materials 11 and 12 are, for example, highly transparent resins such as polymethyl methacrylate, polycarbonate and arton, acrylic ultraviolet curable resins filled with inorganic fine powders such as TiO ₂ and SiO ₂ , and a mixture of silicone resins. It can be easily formed into a shape having the inclined surfaces 11a and 11b by using a mold or the like. It can also be produced by scraping glass with a tool or a grindstone.

The polarization separation film 2 formed on the inclined surfaces 11a and 11b has a function of transmitting only one of the orthogonal linearly polarized light and reflecting the other. Polarization separation film 2 is generally when the reference wavelength of the incident light and lambda _0, using lambda _0/4 the high refractive index layer each having a substantially equal optical thickness H and the low refractive index layer L A basic structure film composed of a repeating structure of HL (HL) m (where m is an integer of 4 or more), or a structure represented by (0.5HL0.5H) m (m is a power of m times). It consists of a certain multilayer film. By forming such a polarization separation film 2, it becomes possible to realize sufficient polarization separation characteristics over a wide wavelength range.

As another example of the configuration of the polarization separation film, an optically transparent high refractive index layer H having a predetermined refractive index with respect to incident light, and an optically lower refractive index layer than the high refractive index layer H are used. (H2L) m, (H2L) mH, or 2L (H2L) m (where m is 3 to 7), including a basic structure film H2L composed of a transparent low refractive index layer L. And a multilayer film having any one of the following structures: In this multi-layer film, when the 550nm which is a reference wavelength of the incident light and lambda _0, so that the high refractive index layer H and the low refractive index layer L is substantially equal to the optical thickness both the lambda _0/4 By setting to, it functions well as a polarization separation film.

  The quarter-wave plate 3 and the reflective film 4 are laminated in this order, and on the light incident surfaces of the transparent base materials 11 and 12, at positions corresponding to the alternate inclined surfaces 11a and 11b, that is, this In this case, it is provided at a position across the apex angle of the right triangle. The pitch is substantially the same as the slope 11a or 11b, and the width is substantially the same as the width projected on the surface 1A of the transparent substrate 11 or 12 of the slope 11a or 11b.

Here, as the quarter wave plate 3, for example, a composite film obtained by laminating films produced by stretching polypropylene or polycarbonate can be used.
Other examples of the quarter wavelength plate 3 include stretched films using polyethylene, polyvinyl alcohol, polysulfone, polyarylate, and the like, and laminated composite films thereof. As the reflective film 4, a film or the like in which a sputtered film of Al or Ag is formed on a polyethylene terephthalate (PET) base and an increased reflective film made of TiO ₂ and SiO ₂ is formed thereon can be used.

  Next, the function of the polarization beam converting element having the above structure will be described with reference to FIG. In this polarization beam converting element, incident light projected from the back direction, that is, the incident side surface 1A is condensed by the lens array, for example, when a lens array is provided, and the quarter wavelength plate 3 and the reflection film 4 are formed. It is focused on the area where it is not formed.

  Of these condensed light, linearly polarized light in one polarization direction, for example, a P-polarized wave indicated by an arrow P, passes through the polarization separation film 2 and is transparent while maintaining the polarization direction (as a P-polarized wave). It penetrates the substrate 11.

The linearly polarized light in the other polarization direction, for example, the S-polarized wave indicated by the broken-line arrow S is reflected by the polarization separation film 2 and further reflected by the adjacent polarization separation film 2, toward the light incident side, and ¼. The light enters the wave plate 3 and is reflected by the reflective film 4. Then, it passes through the quarter-wave plate 3 again and is converted into a P-polarized wave. That is, the S-polarized wave is transmitted twice through the quarter-wave plate 3, and the phase of the ordinary light component and the extraordinary light component are shifted by ½ wavelength, so that the linearly polarized light in the orthogonal direction (P-polarized wave) is obtained. Converted.
The converted P-polarized wave passes through the polarization separation film 2 and is emitted from the transparent substrate 11. In this way, most of the incident light is converted into one linearly polarized wave, in this case a P-polarized wave.

  In the first embodiment described above, the structure of the transparent substrate having the polarization separation film is characteristic, and it can be manufactured by a simple process. Hereinafter, an embodiment of a method for manufacturing a polarization beam converting element according to the present invention will be described.

(2) Second Embodiment To produce a transparent base material having a polarization separation film, first, as shown in FIG. 3, a first transparent member 31 in which opposed slopes are repeatedly formed is prepared. The first transparent member 31 can be easily formed by a technique such as injection molding. It is also possible to fabricate by using an ultraviolet curable resin or the like and pouring the resin onto a mold having slope grooves and curing the resin with ultraviolet rays.

  Next, as shown in FIG. 4, a polarization separation film 32 is formed so as to cover the inclined surface of the first transparent member 31. The polarization separation film can be formed, for example, by alternately laminating a high refractive index layer and a low refractive index layer. Each layer may be formed by sputtering, vapor deposition, or the like.

  Next, as shown in FIG. 5, for example, a transparent base material 33 such as acrylic is stacked on the inclined surface of the first transparent member 31, and uncured ultraviolet rays are interposed between the transparent base material 33 and the first transparent member 31. A light transmissive member 34 made of a cured resin or the like is filled. In this state, ultraviolet rays are irradiated through the transparent base material 33 to cure the uncured resin with ultraviolet rays to form the second transparent member 35. By removing the transparent base material 33, a flattened second transparent member 35 is formed as shown in FIG. In addition, thermosetting etc. are employable as a hardening method of transparent uncured resin.

  Then, the slopes 11a and 11b are provided from the front surface to the back surface by removing the removal portion 13 indicated by oblique lines on the surfaces of the transparent members 31 and 35 by, for example, mirror polishing, etching, or chemical treatment. The transparent base materials 11 and 12 having the configuration shown in FIG. 1 can be formed.

  Thereafter, for example, a quarter-wave plate and a reflective film are selectively formed on the incident-side surface 1A of the transparent substrate 12 at every other position corresponding to a pair of adjacent inclined surfaces 11a and 11b facing each other. A film is formed by vapor deposition, sputtering, or the like to complete a polarization beam conversion element having the configuration of the present invention as shown in FIG. These quarter-wave plates and reflective films can be easily formed by laminating films prepared in advance.

  In addition, in the Japanese Patent Application No. 2003-47851 (filed on February 25, 2003), the applicant of the present invention, as shown in FIG. A polarization beam converting element is proposed in which a polarization separation film 2 is formed on the inclined surface, and a quarter wave plate 3 and a reflective film 4 are formed on the light incident side surface corresponding to the pair of inclined surfaces. .

  According to the polarization beam conversion element of the present invention, as with the polarization beam conversion element proposed in the above-mentioned application, the manufacturing process is simple and a large area can be manufactured. Compared with the polarization beam conversion element, the thickness can be reduced to about 1/2 or less, and a smaller and thinner polarization beam conversion element can be provided.

(3) Third Embodiment Next, an embodiment of a liquid crystal display device using a polarized beam conversion element according to the present invention will be described. In this example, the case where the present invention is applied to a projector type liquid crystal display device is shown, but the present invention is not limited to this example, and is applied to the case where a polarization beam converting element is used in other various panel type liquid crystal display devices. It goes without saying that it can be done.

  FIG. 8 is a diagram illustrating a schematic configuration of a projector-type liquid crystal display device. 51 is a light source, 52 and 53 are integrator lenses, 54 is a polarization beam converting element having the above-described configuration, 55, 60, 62 and 66 are condensing lenses, and 56, 59, 64 and 66 are total reflection type mirrors. It is. For example, 57 is a dichroic mirror that transmits blue light and reflects green light and red light, and 58 is a dichroic mirror that reflects green light and transmits red light, which separates red, blue, and green light.

  The liquid crystal plates 61, 63, and 67 corresponding to the respective colors B, G, and R are disposed at positions facing the incident surface of the cross prism 68, respectively. Reference numeral 69 denotes a projection lens.

  An incident / exit mode of each color light in such a configuration will be described. White light from the light source 51 is efficiently collected by the integrator lenses 52 and 53, and converted by the polarization beam conversion element 54 into, for example, a P-polarized wave into an S-polarized wave (or an S-polarized wave into a P-polarized wave). , S-polarized waves (or P-polarized waves) are taken out, reflected through a lens 55 by a mirror 56, and incident on a dichroic mirror 57.

The blue light passes through the dichroic mirror 57, is reflected by the mirror 59, and enters the liquid crystal plate 61 for blue light via the lens 60.
Similarly, green light out of the light reflected by the dichroic mirror 57 is reflected by the dichroic mirror 58 and enters the liquid crystal plate 63 for green light via the lens 62.

The red light transmitted through the dichroic mirror 58 is incident on the liquid crystal plate 67 for red light through the mirrors 64 and 65 and the lens 66.
Then, although not shown in the figure, liquid crystal plates 61, 63 and 67 corresponding to the respective colors are inputted with a light modulation signal corresponding to a display signal from a predetermined modulation circuit to perform light modulation, and are synthesized by a cross prism 68 and are projected by a projection lens 69. Is magnified and projected on the screen.

  As described above, in the liquid crystal display device, by using the polarization beam conversion element to align the polarization direction of the white light, only one of the conventional S-polarized wave and P-polarized wave is used, and the other polarized wave is used as heat. Although it has been abandoned, utilization efficiency can be remarkably improved by aligning the polarization components of light from the light source as described above.

According to the present invention, since the manufacturing process of the polarization beam converting element is simplified and the area can be easily increased, the cost can be reduced, and the cost of the liquid crystal display device using the same can be reduced. Reduction can be achieved.
Furthermore, as described above, the configuration of the present invention can be further downsized, which is advantageous for downsizing the liquid crystal display device.

Next, specific examples to which the present invention is applied will be described.
Example 1
A substrate having a sawtooth cross section having a 45-degree slope having an inclination angle of 45 degrees with respect to the bottom surface and extending in a direction perpendicular to the slope direction of the slope was produced. The substrate was produced by injection molding polymethyl methacrylate (PMMA), and this was used as the transparent member A.

Next, a polarization separation film was formed on the inclined surface. This polarized light separation film was formed by repeatedly forming the Y ₂ O ₃ vapor deposition film H and the MgF ₂ vapor deposition film L as a set to form a total of 32 layers. The film thickness of the Y ₂ O ₃ vapor deposition film H was 78.6 nm, and the film thickness of the MgF ₂ vapor deposition film L was 99.6 nm.

  After forming the polarization separation film, an ultraviolet curable acrylic resin was applied and filled from above, and an acrylic transparent substrate was further covered from above to spread the acrylic resin. In this state, the ultraviolet curable acrylic resin, which is a transparent uncured resin, was cured with ultraviolet light and integrated to form a transparent member B. Thereafter, the surface was polished until the slope was exposed.

  Furthermore, a film having an optical thickness of ¼ wavelength and a reflective film were bonded to each other through an adhesive layer across a pair of slopes where the tops meet each pitch of the slope. When the polarization beam conversion element thus produced is measured by adhering an antireflection film having an average reflectance of 0.2% to the light emitting side surface of the transparent base material with a pressure-sensitive adhesive, it is P-polarized light in the vicinity of a wavelength of 550 nm. While transmitting only waves, the light transmittance was 85%. In addition, the manufacturing process can be greatly simplified as compared with the conventional polarization beam converting element.

Example 2
The structure of the transparent substrate in the polarizing beam conversion element of this example is the same as that of Example 1 described above, but the transparent member A was formed of an ultraviolet curable resin in which TiO ₂ fine particles were kneaded and filled.

That is, TiO ₂ fine particles were mixed and dispersed in monomers, polymers and mixtures thereof that can be cross-linked by ultraviolet irradiation or heating. Specifically, a mixed solvent composed of 25% by weight of methyl ethyl ketone and 75% by weight of cyclohexanone was prepared, and the resulting mixed solvent was used as a solvent, and a photopolymerization initiator (Irgacure 369: manufactured by Ciba / Specialty / Chemicals) was added to the mixed solvent. .3 wt% and sensitizer (Kayacure RTX: manufactured by Nippon Kayaku Co., Ltd.) 0.1 wt% were dissolved and mixed. Further, epoxy acrylate (bisphenol A- epichlorohydrin / acrylic acid) 2 wt%, trimethylol propane triacrylate 2 wt%, silicone resin: mixed (JCR6122, manufactured by Dow Corning Toray Silicone Co.) 1 wt%, the TiO ₂ powder dispersion 15 wt% Kneaded. A total amount of 1 kg of material was kneaded for 5 hours in a stainless steel sealed container, and then kneaded for 5 hours while drying to form a paste-like resin composition while lowering the solvent ratio.

Next, this paste-like resin composition was spread through a PET film by a method similar to that described above with reference to FIG. 5 on a mold having a 45-degree inclined groove facing each other. Then, after making it harden | cure at 130 degreeC, ultraviolet curing was further performed.
Then, it peeled from the metal mold | die and the transparent member A was produced.

In this case, since the refractive index of the transparent member A was 1.8, the polarization separation film had a seven-layer structure of TiO ₂ and SiO ₂ . That, SiO ₂ film (thickness having a TiO ₂ film (thickness 55.9nm) H having an optical thickness corresponding to a quarter wavelength at 550 nm, the optical thickness corresponding to 1/2 wavelength at 550 nm 188.4Nm 2L was laminated in the order of H, 2L, H, 2L, H, 2L, and H, and a film having a seven-layer structure was formed by sputtering.

Next, similarly to the transparent member A, the transparent member B is formed by filling and applying a resin slurry in which TiO ₂ fine particles are kneaded and dissolved, and then curing by heating and ultraviolet irradiation, and similarly polishing until the slope is exposed. Went. When the polarization beam conversion element thus produced is measured by attaching an antireflection film having an average reflectance of 0.2% to the light emission side surface of the transparent substrate via an adhesive, While showing 92% centering on a wavelength of 550 nm, the manufacturing process is greatly simplified as compared with the conventional polarization beam separating / converting element.

  In the above embodiment, an example in which the transparent member A and the transparent member B have a refractive index of 1.49 and 1.8 has been described, but the refractive index is an intermediate value between them, for example, 1.6 or 1 Even in the case of .7, it is possible to realize the transparent base material structure in the same manner. For each refractive index, the film configuration of the polarization separation film is (HL) m or (0.5HL0.5H) m (m) based on the target specification and cost requirement of the polarization conversion rate as the polarization beam separation element. Is a power of m times), and is further selected from (H2L) m, (H2L) mH, or a film configuration based on 2L (H2L) m and a derivative film configuration derived therefrom. However, in any case, the polarization separation film is formed on one substrate or simultaneously formed on the repeated 45-degree inclined grooves, and a three-dimensional block grinding process such as slicing, bonding and double-side polishing is required. Therefore, it is highly productive.

  Furthermore, in the present invention, since the polarization separation film is formed by sputtering or vapor deposition on the 45-degree slopes facing each other, the groove opening angle is 90 degrees, and the shadowing effect when forming the sputtering thin film by the so-called groove wall is achieved. A uniform film thickness can be formed up to the bottom of the groove. In that sense, it is possible to avoid the adverse effect on the uniformity of the film thickness due to the shadow of the vapor deposition beam by the triangular groove wall, which becomes a problem in the invention described in each publication reported as the prior art. Also in this sense, the productivity and yield of the polarization beam conversion element of the present invention are high, and an inexpensive polarization beam conversion element can be supplied.

  In each of the above-described embodiments, the case where the transparent member A is formed using a resin material filled with a resin material and an inorganic material has been described. However, it is not excluded that the transparent member A is formed of glass. A method of forming a glass groove having a 45 ° slope on a glass substrate in a glass viscous state, or a method of processing a grindstone and polishing a groove are also possible. In this case as well, although not as much as groove formation by plastic molding, the overall process can be a simpler and cheaper process than the conventional method.

  Therefore, by using such a polarized beam conversion element according to the present invention for a liquid crystal panel display, for example, the use efficiency of the light source is high, low power consumption or high luminance is achieved, and cost is reduced. You can also.

It is a schematic sectional drawing which shows an example of this invention polarization beam conversion element. It is explanatory drawing which shows typically the conversion aspect of the incident light in this invention polarization beam conversion element. It is one process figure which shows an example of the manufacturing method of the polarizing beam conversion element of this invention. It is one process figure which shows an example of the manufacturing method of the polarizing beam conversion element of this invention. It is one process figure which shows an example of the manufacturing method of the polarizing beam conversion element of this invention. It is one process figure which shows an example of the manufacturing method of the polarizing beam conversion element of this invention. It is a schematic sectional drawing which shows an example of a polarization beam conversion element. It is a block diagram of an example of a liquid crystal display device. It is a schematic sectional drawing which shows an example of the conventional polarizing beam conversion element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent base material 1A Incident side surface 1B Back surface 2 Polarization separation film 3 1/4 wavelength plate 4 Reflection film 11 Transparent base material 12 Transparent base material 31 1st transparent member 32 Polarization separation film 33 Transparent base material 34 Light transmission member 35 Second transparent member 101 Transparent substrate 102 Polarization separation film 103 Mask 104 Half-wave plate

Claims (6)

From the front surface to the back surface of the transparent substrate, the slopes facing each other with different inclination directions are alternately and repeatedly formed,
A polarization separation film is formed on the slope,
It is characterized in that at least a quarter-wave plate and a reflective film are disposed at every other position corresponding to a pair of adjacent slopes facing each other on the light incident side surface of the transparent substrate. Polarizing beam conversion element. 2. The polarization beam converting element according to claim 1, wherein the inclined angle of the inclined surface is approximately 45 degrees with respect to the light incident side surface of the transparent substrate. The lens array which condenses incident light is provided in the area | region in which the said 1/4 wavelength plate and reflection film are not formed of the light-incidence side surface of the said transparent base material of Claim 1 characterized by the above-mentioned. Polarized beam conversion element. The lens array which condenses incident light is provided in the area | region in which the said 1/4 wavelength plate and reflection film are not formed in the light-incidence side surface of the said transparent base material, The characterized by the above-mentioned. Polarized beam conversion element. Forming a polarization separation film on the inclined surface of the first transparent member formed with inclined surfaces facing each other with different inclination directions;
Forming the second transparent member by embedding the slope;
A step of removing a part of each surface of the first and second transparent members until the inclined surface is exposed, and having inclined surfaces facing each other from the light incident oblique side surface to the back surface, and polarization separation on the inclined surface Create a transparent substrate formed with a film,
Polarized light characterized in that at least a quarter-wave plate and a reflective film are formed at every other position corresponding to a pair of adjacent slopes facing each other on the light incident side surface of the transparent substrate. Manufacturing method of beam conversion element. A liquid crystal display device having at least a light source, a polarized beam conversion element, and a liquid crystal plate,
The polarized beam conversion element is
The slopes facing each other with different inclination directions are formed alternately and repeatedly from the front surface to the back surface of the transparent substrate,
A polarization separation film is formed on the slope,
It is characterized in that at least a quarter-wave plate and a reflective film are disposed at every other position corresponding to a pair of adjacent slopes facing each other on the light incident side surface of the transparent substrate. Liquid crystal display device.

Images