JP2008241936A - Display, back light unit for display, optical sheet, and manufacturing method of optical sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost, high-precision optical sheet which has a repetitive array structure of unit lenses or lens prisms. <P>SOLUTION: The optical sheet 38 used for lighting optical path control over a back light unit for display has a transparent base material 39 formed in a thin-film shape, a plurality of unit lenses 44 disposed on one surface 39b of the transparent substrate 39 in stripes in parallel, and a light reflective layer 48 disposed on the other surface 39a of the transparent base material 39, formed of photolysis resin containing white pigment, and having a light reflecting function. Then the light reflective layer 48 has a plurality of opening portions 46 corresponding to the plurality of unit lenses 44 one to one and disposed in stripes in parallel. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improvement of an optical sheet that provides a brightness enhancement function to a display typified by a liquid crystal display that is an image display device incorporating a liquid crystal display element, a method of manufacturing the optical sheet, a display to which the optical sheet is applied, and The present invention relates to a display backlight unit.

  Unlike other image display devices such as a plasma display panel, an organic EL display, a field emission display, etc., the liquid crystal display is not a self-luminous type, and therefore requires a backlight unit 40 including a light source 23 (see FIG. 4). In most cases. In this case, the power consumption of the backlight unit 40 is added to the power consumption necessary for driving the liquid crystal display element 42.

  Therefore, in order to reduce the power consumption of the backlight unit 40 as much as possible, an attempt is made to reduce the total power consumption of the display by using an optical sheet having a brightness enhancement function.

  As a brightness enhancement sheet for reducing the power consumption of the backlight unit 40, a brightness enhancement film (BEF: Brightness Enhancement Film) developed by 3M USA is known (Patent Document 1).

  A liquid crystal display in which a prism shape is formed on one surface of a translucent film and a transparent convex dot is formed on the other surface, as in BEF, and further combined with a light guide plate and a diffusion film The device is provided as a liquid crystal display device with high brightness and no moiré phenomenon.

  As shown in FIG. 5, BEF is a film in which unit prisms 72 having a triangular cross section are periodically arranged in one direction on a member 70. The prism 72 has a size (pitch) larger than the wavelength of light. BEF collects light from “off-axis” and redirects this light “on-axis” or “recycle” towards the viewer. To do.

  When using the display (when observing), the BEF increases the on-axis brightness by reducing the off-axis brightness. Here, “on-axis” is a direction that coincides with the visual direction of the viewer, and is generally the normal direction to the display screen (direction F shown in FIG. 5).

  When the repetitive array structure of the prisms 72 is arranged in only one direction, only the direction change or recycling in the parallel direction is possible, and in order to control the luminance of the display light in the horizontal and vertical directions, the prism groups are arranged in parallel. Two sheets are stacked and combined so that the directions are substantially orthogonal to each other.

  The adoption of BEF allows display designers to achieve the desired on-axis brightness while reducing power consumption.

  As patent documents disclosing that a brightness control member having a repetitive array structure of prisms 72 typified by BEF is adopted for a display, many are known as exemplified in Patent Documents 1 to 3. ing.

  In the optical sheet using the BEF as a brightness control member as described above, the light 23a from the light source 23 is finally emitted at a controlled angle φ by the refraction action X as shown in FIG. Thus, it is possible to control to increase the intensity of light in the visual direction F of the viewer.

  However, at the same time, the light component due to the reflection / refraction action Y is unnecessarily emitted in the lateral direction without proceeding in the visual direction F of the viewer.

Therefore, the light intensity distribution emitted from the optical sheet using BEF as shown in FIG. 5 and FIG. 6 has the highest light intensity in the visual direction F of the viewer, but the light emitted wastefully from the lateral direction. In order to overcome such a drawback, there is also a backlight unit using an optical sheet having a repetitive array structure of unit lenses 44 instead of a prism as shown in FIG. Reference 4).

  A lens 44 for guiding the light traveling in the optical sheet 38 to the liquid crystal display element 42 is provided on the surface of the transparent base 39 of the optical sheet 38 on the liquid crystal display element 42 side. As shown in the perspective view of FIG. 8, the lens 44 has an array structure in which a plurality of unit lenses 44 are repeatedly formed.

  Furthermore, a light reflecting layer 48 having a stripe pattern is provided on the other surface by having an opening 46 in the vicinity of the focal plane of each unit lens 44.

The light reflecting layer 48 is obtained by mixing a mixture of white titanium dioxide (TiO ₂ ) powder in a transparent adhesive solution or the like with a predetermined pattern (when the unit lens is a semi-cylindrical convex cylindrical lens group, a unit lens 44 is formed in a stripe shape having an opening 46 corresponding to 1: 1, and is formed (or transferred).

  FIG. 9 is an explanatory diagram showing optical path control characteristics of a backlight when the optical sheets of FIGS. 7 and 8 are applied to a backlight unit.

  Of the light emitted from the diffusion film 32, only the light that has passed through the opening 46 enters the lens 44 and is emitted after being condensed in a certain direction by the lens 44. Then, the light enters the polarizing plate 49 and only light having a predetermined polarization component is guided to the liquid crystal display element 42.

  On the other hand, the light that could not pass through the opening 46 is reflected by the light reflecting layer 48, returned to the diffusion plate 26 side, and further, the reflecting plate 27 provided at the bottom of the lamp house 21 that houses the light source 23. Led to. Then, the light is incident on the diffusion plate 26 again by being reflected by the reflection plate 27 and is diffused again on the diffusion plate 26. 9, and is squeezed and emitted by a lens 44 within a predetermined angle φ as shown in FIG. 9.

In the backlight unit 40 using such an optical sheet 38, the size and position of the opening 46 of the optical sheet 38 are adjusted, and the light is emitted from the lens 44 in the front direction F while improving the light use efficiency. It can be controlled to increase the proportion of light.
JP-A-6-102506 Japanese Patent Publication No. 1-378001 Japanese National Patent Publication No. 10-506500 JP 2000-284268 A Japanese Patent No. 3243166

  However, the backlight unit disclosed in Patent Document 4 is advantageous in terms of utilization efficiency of the backlight light source. However, in addition to the production of the lens 44, the position and shape of the stripe pattern of the light reflecting layer 48 are highly accurate. Need to be formed.

  In Patent Document 4, a printing method is described as a method of forming a stripe pattern of the light reflecting layer 48. However, in the printing method, when the lens pitch is made finer, the position and shape of the stripe pattern of the light reflecting layer 48 are changed. There was a problem that it was difficult to carry out with high accuracy.

  In addition, so-called self-alignment that accurately defines the position corresponding to the non-condensing portion of each unit lens 44 by using the condensing characteristic of the lens 44 itself with respect to the photosensitive resin layer formed on the opposite lens surface of the optical sheet 38. The method is effective in accurately opening the condensing part of the unit lens 44 (accurately shielding the non-condensing part of the unit lens 44).

  As a conventional technique, an ionizing radiation curable resin layer is formed on the flat surface of the optical sheet 38 using the method disclosed in Patent Document 5, and the light source 23 and the optical sheet 38 are connected to the cylindrical lens 44. A band-shaped light beam (slit light) extending in the longitudinal direction of the lens 44 (L direction shown in FIG. 8) while being relatively moved in the juxtaposed direction is perpendicular to the flat surface of the optical sheet 38 from the lens 44 side. Irradiate to cure the uncured resin in the portion condensed by each unit lens 44, and transfer the light reflecting layer 48 to the resin surface (non-condensing portion where viscosity remains) other than the cured portion. There is a proposal for forming a stripe pattern of the light reflecting layer 48 on the flat surface.

  However, when the transfer method using the self-alignment method is carried out as a means for forming the light reflecting layer 48, the ink layer of the transfer foil has poor cutting properties and the direction of the peeling direction is generated, and the tailing at the time of peeling is performed. As a result, there is a problem that a fine pattern cannot be formed.

  In the method disclosed in Patent Document 5, there are two photosensitive resin layers (for defining the pattern formation location of the light reflection layer 48) and transfer foil (for forming the pattern of the light reflection layer 48). A material is required, and secondary materials such as a release film are also generated, resulting in high costs.

  The present invention has been made in view of the above-described conventional problems, and in an optical sheet having a repetitive array structure of unit lenses or unit prisms, a low-cost and high-precision optical sheet, a manufacturing method thereof, and the optical An object is to provide a backlight unit and a display using a sheet.

  In order to achieve the above object, the present invention takes the following measures.

  That is, according to the first aspect of the present invention, in an optical sheet used for illumination light path control in a backlight unit for a display, a transparent support having a thin film shape and one surface of the transparent support are arranged in parallel in stripes. A plurality of unit lenses or unit prisms, and a light reflecting layer which is disposed on the other surface of the transparent support and is made of a photodegradable resin containing a white pigment and has a light reflecting function. The light reflecting layer has a plurality of openings arranged in parallel in a stripe shape corresponding to 1: 1 for each of the plurality of unit lenses or unit prisms.

The invention according to claim 2 is the optical sheet according to claim 1, wherein the arrangement pitch of the unit lenses or unit prisms is 0.3 × 10 ⁻³ m or less.

The invention according to claim 3 is the optical sheet according to claim 1, wherein the thickness of the transparent support is from 30 × 10 ⁻⁶ m to 200 × 10 ⁻⁶ m.

The invention according to claim 4 is the optical sheet according to claim 1 or 2, wherein the thickness of the light reflecting layer is 5 × 10 ⁻⁶ m or more and 30 × 10 ⁻⁶ m or less.

  The invention according to claim 5 is the optical sheet according to any one of claims 1, 2, and 5, wherein the transmittance of the light reflecting layer is 15% or less.

  The invention according to claim 6 is the optical sheet according to any one of claims 1 to 5, wherein the transparent support is insoluble in the photodegradable resin solvent and the developer.

  According to a seventh aspect of the present invention, at least the optical sheet according to any one of the first to sixth aspects of the present invention is provided on the non-display surface side of the image display element defining the display image, from the non-display surface side. A backlight unit for a display comprising: a direct light source for supplying illumination light;

  The invention of claim 8 is an image display element made of liquid crystal that defines a display image according to transmission / light-shielding in pixel units, and any one of claims 1 to 6 arranged on the non-display surface side of the image display element. A display comprising the optical sheet according to claim 1 and a light source which is a cold cathode ray tube or an LED for supplying light to the optical sheet.

  The invention of claim 9 is a method for producing an optical sheet according to any one of claims 1 to 6 used for illumination light path control in a backlight unit for display, wherein the light reflecting layer is formed. A process of uniformly forming a photodegradable resin containing a white pigment on the other surface of the transparent support, and light that causes photolysis is irradiated from one surface side of the transparent support, on the other surface And the step of removing the photodegradable resin in the condensing region where the light is collected by the unit lens or the unit prism by the exposure process, and the light in the region other than the condensing region on the other surface And patterning the decomposable resin so that it remains without being exposed.

  The invention according to claim 10 is the method for producing an optical sheet according to claim 9, wherein the transparent support is insoluble in the photodegradable resin solvent and the developer.

  According to the present invention, in an optical sheet having a repetitive array structure of unit lenses or unit prisms, a low-cost and high-precision optical sheet is obtained by using a photodegradable resin containing a white pigment in a stripe of a light reflecting layer. The manufacturing method thereof, the backlight unit and the display using the optical sheet can be realized.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  In addition, the code | symbol in the figure used for description of each following embodiment attaches | subjects and shows the same code | symbol about the same part as FIG. 4 thru | or FIG.

(First embodiment)
As already described with reference to FIG. 8, the optical sheet 38 according to the first embodiment of the present invention has one surface (on the upper side in the drawing) of the transparent substrate 39 which is a transparent support having a thin film shape. A plurality of unit lenses 44 arranged in parallel in a stripe shape on the other surface (the lower surface in the figure) of the transparent base material 39 in a stripe shape corresponding to the stripe of the unit lens 44. A plurality of light reflecting layers 48 having a light reflecting function arranged in parallel are provided.

  The transparent substrate 39 is made of a material that is insoluble in the photodegradable resin solvent and the developer. The light reflecting layer 48 is made of a photodegradable resin containing a white pigment and has a light transmittance of 15% or less. An opening 46 is provided between the light reflecting layers 48. The arrangement position of the opening 46 corresponds to the vicinity of the focal plane of each unit lens 44.

  That is, the light reflection layer 48 corresponds to each of the plurality of unit lenses 44 in the same manner, and the opening portion 46 also corresponds to each of the plurality of unit lenses 44 in a ratio of 1: 1. By alternately arranging the portions 46, the light reflecting layer 48 having a stripe pattern is provided.

The arrangement pitch of the unit lenses 44 is 0.3 × 10 ⁻³ m or less, and the thickness of the transparent base material 39 is 30 × 10 ⁻⁶ m or more and 200 × 10 ⁻⁶ m or less. The thickness of the light reflecting layer 48 is ^{5 × 10 -6 m~30 × 10 -6} m.

  Such an optical sheet 38 is used for illumination light path control in a backlight unit 40 for display as shown in FIG. That is, the optical sheet 38 disposed on the non-display surface side (lower side in the figure) of the liquid crystal display element 42 that is an image display element that defines a display image according to transmission / light shielding in pixel units, and the lower side thereof Further, a backlight unit 40 is configured by a direct-type light source 23 that is arranged and is provided with a cathode ray tube or an LED that supplies light to the optical sheet 38. Further, a display is configured by combining the backlight unit 40 with a liquid crystal display element 42. The light supplied from the light source 23 is emitted after being condensed in a certain direction by the optical sheet 38 as described above. Then, the light enters the polarizing plate 49 and only light having a predetermined polarization component is guided to the liquid crystal display element 42.

  Next, a method for manufacturing the optical sheet 38 according to the present embodiment configured as described above will be described with reference to FIGS.

First, as shown in FIG. 1A, a layer made of a photodegradable resin 48 a containing a white pigment is formed on the non-lens surface 39 a of the transparent base material 39. As the transparent substrate 39, a PET film (Toyobo: A4300) was used, and its thickness was 75 × 10 ⁻⁶ m. Further, a positive photoresist (LC-120 manufactured by Rohm and Haas) was used for the photodegradable resin 48a, and TiO ₂ (titanium oxide) was used for the white pigment. The mixing ratio of the photodegradable resin 48a containing a white pigment is as follows.
Photodegradable resin: 95% by weight
White pigment: 5% by weight
The solvent of the photodegradable resin 48a was propylene glycol monomethyl ether acetate.

  The photodegradable resin 48a containing such a white pigment is uniformly applied to the non-lens surface 39a of the transparent substrate 39 by a known coating method, that is, roll coating, gravure coating, curtain flow coating, spin coating or the like. Then, a layer made of the photodegradable resin 48a was formed. The dissolution of the transparent substrate 39 by the solvent of the photodegradable resin 48a did not occur.

  In addition to such a wet-type formation method, a layer made of the photodegradable resin 48a can be formed by forming the photodegradable resin 48a into a dry film and laminating it with the transparent substrate 39.

  On the other hand, on the lens surface 39b of the transparent base material 39, a cylindrical lens group 44 made of a cured product of UV curable resin (material: epoxy acrylate) was formed.

As shown in FIG. 2, the lens 44 is formed by applying an ultraviolet curable resin to the transparent base material 39 to form a layer made of an ultraviolet coin resin, passing through the lens molding roll 62 and simultaneously transferring the lens molding roll shape. The lens 44 was formed by curing the layer made of the ultraviolet curable resin by irradiating the ultraviolet ray 61 from the ultraviolet exposure device 60 such as a high pressure mercury lamp or a metal halide lamp. The lens pitch P was 0.14 × 10 ⁻³ m. In addition, the lens 44 may be formed by extrusion using a thermoplastic resin.

  FIG. 1B shows a process of irradiating the optical sheet 38 having a non-lens surface 39a formed with a layer made of the photodegradable resin 48a with light that causes a photodecomposition reaction from the lens surface 39b side. FIG.

After forming the layer made of the photodegradable resin 48a, the optical sheet 38 was irradiated with light 50 for causing photodecomposition of the photodegradable resin from the lens surface 39b side of the transparent base material 39 to be exposed. The light used for the exposure was ultraviolet light (wavelength: 365 nm (365 × 10 ⁻⁹ m)).

Among the photodegradable resin 48a, photolysis in portions 48a ₁ which is condensed is generated by the lens function of the unit lenses 44, photolysis in part 48a ₂ is not condensed is not generated by the lens function.

FIG. 1 (c) after exposure, subjected to a development process, is a view illustrating a step of removing a portion 48a ₁ which is among photolysis photolytic resin 48a.

After exposure, followed by development to remove the portion 48a ₁ which is photodegradable. As a developing solution, Microposit 303A developer manufactured by Rohm and Haas was used. The developer was an aqueous sodium hydroxide solution. At this time, dissolution of the optical sheet 38 by the developer did not occur. The portion 48 a ₁ removed by development becomes an opening 46. Further, the remaining portion 48a ₂ after development became the light reflection layer 48, the thickness thereof was 15 × 10 ⁻⁶ m, and the light transmittance was 10%.

  Thus, the optical sheet 38 having a lens pattern and a light reflective stripe pattern can be manufactured using the photodegradable resin 48a.

  As described above, in the method for manufacturing an optical sheet according to the present embodiment, patterning is performed by using the condensing function of the lens 44 of the optical sheet 38 and the light reflecting layer 48 is obtained by the above-described action. Since the photodegradable resin 48a containing a white pigment is used, the position and shape of the stripe can be created with high accuracy in creating the stripe pattern.

Moreover, the material of the light reflection layer 48 is only the photodegradable resin 48a having a light reflection function by containing a white pigment, and it is also possible to reduce auxiliary materials such as a release film. Therefore, the material cost can be reduced, so that the production can be performed at a low cost. The thickness of the light reflection layer 48 is 5 × 10 ⁻⁶ m or more and 30 × 10 ⁻⁶ m, and a desired light reflectance can be obtained. In addition, the transmittance of the light reflecting layer 48 is 15% or less, and there is no problem of penetrating transmitted light due to light transmitted through the light reflecting layer 48.

  In addition, the conventional photosensitive resin layer and the transfer foil type multilayer structure are compared with the four steps of the photosensitive resin layer forming process, the exposure process, the transfer foil laminating process, and the transfer foil peeling process. In the manufacturing method according to the embodiment, the light reflecting layer 48 has a single layer structure made of the photodegradable resin 48a. Therefore, the photodegradable resin layer forming step as shown in FIG. Therefore, it is possible to reduce the number of processes because the exposure process as shown in FIG. 3 and the patterning process as shown in FIG. By reducing the number of steps, the yield can be improved and the running cost can be reduced, so that the production can be performed at a lower cost.

Further, by setting the arrangement pitch P of the unit lenses 44 to 0.3 × 10 ⁻³ m or less, it is possible to cope with high resolution of the display, and the thickness of the transparent substrate 39 is 30 × 10 ^−6. m to 200 × 10 ⁻⁶ m, and the strength of the transparent substrate 39 can be maintained.

  Furthermore, since the transparent substrate 39 is insoluble in the photodegradable resin solvent and the developer, the step of uniformly forming the photodegradable resin 48a as shown in FIG. 1A, and FIG. In the patterning process as shown in FIG. 4, since there is no damage such as a change in the shape of the lens 44 on the transparent base material 39 and a distortion of the transparent base material 39, it is possible to prevent the occurrence of a change in optical characteristics such as a luminance distribution. Become.

(Second Embodiment)
In the first embodiment, the optical sheet 38 having the unit lens 44 has been described as an example. However, in the present embodiment, an optical sheet having the unit prism 72 instead of the unit lens 44 will be described.

  That is, the optical sheet according to the present embodiment differs from the optical sheet 38 shown in FIG. 8 only in that the unit prism 72 is disposed instead of the unit lens 44, and the other configurations are the same. Will be omitted, and only the manufacturing method will be described with reference to FIGS. 3 (a) to 3 (c).

First, as shown in FIG. 3A, a layer made of a photodegradable resin 48a containing a white pigment on the non-prism surface 39a (the same surface as the non-lens surface in the first embodiment) of the transparent substrate 39. Form. A PET film (Toyobo Co., Ltd .: A4300) was used for the transparent substrate 39 in the same manner as in the first embodiment, and the thickness was 75 × 10 ⁻⁶ m. Further, a positive photoresist (LC-120 manufactured by Rohm and Haas) was used for the photodegradable resin 48a, and TiO ₂ (titanium oxide) was used for the white pigment. The mixing ratio of the photodegradable resin 48a containing the white pigment and the solvent are the same as those in the first embodiment.

  The photodegradable resin 48a containing such a white pigment is uniformly applied to the non-prism surface 39a of the transparent substrate 39 by a known coating method, that is, roll coating, gravure coating, curtain flow coating, spin coating or the like. Then, a layer made of the photodegradable resin 48a was formed. The dissolution of the transparent substrate 39 by the solvent of the photodegradable resin 48a did not occur.

  In addition to such a wet-type formation method, a layer made of the photodegradable resin 48a can be formed by forming the photodegradable resin 48a into a dry film and laminating it with the transparent substrate 39.

  On the other hand, a unit prism 72 is disposed on the prism surface 39b of the transparent base material 39 (the same surface as the lens surface in the first embodiment).

As in the case of forming a lens, the prism 72 is formed by applying an ultraviolet curable resin to the transparent base material 39 to form a layer made of an ultraviolet coin resin, and passing it through a prism molding roll (not shown). At the same time as transferring the roll shape, a prism 72 was formed by irradiating ultraviolet rays 61 from an ultraviolet exposure device 60 such as a high-pressure mercury lamp or a metal halide lamp to cure the layer made of the ultraviolet curable resin. The arrangement pitch P was 0.14 × 10 ⁻³ m. In addition, the prism 72 may be formed by extrusion molding using a thermoplastic resin.

  In FIG. 3B, the optical sheet 38 having the non-prism surface 39a formed with a layer made of the photodegradable resin 48a is irradiated with light 50 that causes a photodecomposition reaction from the prism surface 39b side. It is the figure which showed the process.

After the layer made of the photodegradable resin 48a was formed, the optical sheet 38 was irradiated with light 50 for generating photodecomposition of the photodegradable resin from the prism surface 39b side of the transparent base material 39 and exposed. The light used for the exposure was ultraviolet light (wavelength: 365 nm (365 × 10 ⁻⁹ m)).

Among the photodegradable resin 48a, the portion 48a ₁ in the photolysis hits the refracted light caused by refraction function of the unit prisms 72, portions 48a ₂ in photolysis light does not hit does not occur.

FIG. 1 (c) after exposure, subjected to a development process, is a view illustrating a step of removing a portion 48a ₁ which is among photolysis photolytic resin 48a.

After exposure, followed by development to remove the portion 48a ₁ which is photodegradable. As a developing solution, Microposit 303A developer manufactured by Rohm and Haas was used. The developer was an aqueous sodium hydroxide solution. At this time, dissolution of the optical sheet 38 by the developer did not occur. The portion 48 a ₁ removed by development becomes an opening 46. Further, the remaining portion 48a ₂ after development became the light reflection layer 48, the thickness thereof was 15 × 10 ⁻⁶ m, and the light transmittance was 10%.

  As described above, even when the unit prism 72 is used as in the present embodiment, the photodegradable resin 48a is used as in the case where the unit lens 44 is used as in the first embodiment. Thus, an optical sheet 38 having a lens pattern and a light reflective stripe pattern can be manufactured.

  As described above, in the method for manufacturing an optical sheet according to the present embodiment, patterning is performed using the refraction function of the prism 72 of the optical sheet 38 and the light reflecting layer 48 is formed by the above-described action. Since the photodegradable resin 48a containing a white pigment is used, the position and shape of the stripe can be created with high accuracy in creating the stripe pattern.

Moreover, the material of the light reflection layer 48 is only the photodegradable resin 48a having a light reflection function by containing a white pigment, and it is also possible to reduce auxiliary materials such as a release film. Therefore, the material cost can be reduced, so that the production can be performed at a low cost. The thickness of the light reflection layer 48 is 5 × 10 ⁻⁶ m or more and 30 × 10 ⁻⁶ m, and a desired light reflectance can be obtained.

  In addition, the conventional photosensitive resin layer and the transfer foil type multilayer structure are compared with the four steps of the photosensitive resin layer forming process, the exposure process, the transfer foil laminating process, and the transfer foil peeling process. In the manufacturing method according to the embodiment, the light reflecting layer 48 has a single-layer structure made of the photodegradable resin 48a. Therefore, the photodegradable resin layer forming step as shown in FIG. The exposure process as shown in FIG. 3 and the patterning process as shown in FIG. 3C can be created, so that the number of processes can be reduced. By reducing the number of steps, the yield can be improved and the running cost can be reduced, so that the production can be performed at a lower cost.

Further, by setting the arrangement pitch P of the unit prisms 72 to 0.3 × 10 ⁻³ m or less, it is possible to cope with high resolution of the display, and the thickness of the transparent base material 39 is 30 × 10 ^−6. m to 200 × 10 ⁻⁶ m, and the strength of the transparent substrate 39 can be maintained.

  Furthermore, since the transparent substrate 39 is insoluble in the photodegradable resin solvent and the developer, the step of uniformly forming the photodegradable resin 48a as shown in FIG. 3A, and FIG. In the patterning process as shown in FIG. 5, since there is no damage such as a change in the shape of the prism 72 to the transparent base material 39 and a distortion of the transparent base material 39, it is possible to prevent the change in optical characteristics such as the luminance distribution. Become.

  The best mode for carrying out the present invention has been described above with reference to the accompanying drawings, but the present invention is not limited to such a configuration. Within the scope of the invented technical idea of the scope of claims, a person skilled in the art can conceive of various changes and modifications. The technical scope of the present invention is also applicable to these changes and modifications. It is understood that it belongs to.

Explanatory drawing which shows the manufacturing method of the optical sheet which concerns on 1st Embodiment. The figure explaining the method of forming a unit lens in the optical sheet which concerns on 1st Embodiment. Explanatory drawing which shows the manufacturing method of the optical sheet which concerns on 2nd Embodiment. The schematic sectional drawing which shows the structural example of a general display. The perspective view which shows the structural example of "BEF" which is an optical sheet of a prior art. The conceptual diagram which shows the optical path control characteristic by the backlight using BEF. The conceptual diagram which shows the structural example of the display using the optical sheet provided with the unit lens repeatedly arranged. The perspective view which shows the structural example of the optical sheet provided with the unit lens arrange | positioned repeatedly. The conceptual diagram which shows the optical path control characteristic of the backlight using the optical sheet provided with the unit lens arrange | positioned repeatedly.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 21 ... Lamp house, 23 ... Light source, 23a ... Light, 26 ... Diffusing plate, 27 ... Reflecting plate, 32 ... Diffusing film, 38 ... Optical sheet, 39 ... Transparent base material, 39a ... Non-lens surface, 39b ... Lens surface, DESCRIPTION OF SYMBOLS 40 ... Backlight unit, 42 ... Liquid crystal display element, 44 ... Lens, 46 ... Opening part, 48 ... Light reflection layer, 48a ... Photodegradable resin, 49 ... Polarizing plate, 50 ... Light, 60 ... Ultraviolet exposure apparatus, 61 ... UV, 62 ... Lens molding roll, 70 ... Member, 72 ... Prism

Claims (10)

In an optical sheet used for illumination light path control in a backlight unit for display,
A transparent support made of a thin film, and
A plurality of unit lenses or unit prisms arranged in parallel in a stripe on one surface of the transparent support,
A light reflecting layer disposed on the other surface of the transparent support, made of a photodegradable resin containing a white pigment, and having a light reflecting function,
The optical sheet according to claim 1, wherein the light reflecting layer has a plurality of openings arranged in parallel in a stripe shape corresponding to 1: 1 for each of the plurality of unit lenses or unit prisms. The optical sheet according to claim 1, wherein an arrangement pitch of the unit lenses or unit prisms is 0.3 × 10 ⁻³ m or less. 3. The optical sheet according to claim 1, wherein the transparent support has a thickness of 30 × 10 ⁻⁶ m or more and 200 × 10 ⁻⁶ m or less. 4. The optical sheet according to claim 1, wherein a thickness of the light reflection layer is 5 × 10 ⁻⁶ m or more and 30 × 10 ⁻⁶ m or less.   The optical sheet according to any one of claims 1 to 4, wherein the light reflection layer has a transmittance of 15% or less.   The optical sheet according to any one of claims 1 to 5, wherein the transparent support is insoluble in a photodegradable resin solvent and a developer. From the non-display surface side to the non-display surface side of the image display element that defines the display image, at least,
The optical sheet according to any one of claims 1 to 6,
A display backlight unit comprising a direct light source for supplying illumination light to the optical sheet in order. An image display element comprising a liquid crystal that defines a display image according to transmission / shading in pixel units;
The optical sheet according to any one of claims 1 to 6 disposed on the non-display surface side of the image display element;
A display comprising a light source that is a cold cathode ray tube or an LED for supplying light to the optical sheet. A method for producing an optical sheet used for illumination light path control in a backlight unit for display,
The optical sheet is
A transparent support made of a thin film, and
A plurality of unit lenses or unit prisms arranged in parallel in a stripe on one surface of the transparent support,
A light reflecting layer disposed on the other surface of the transparent support, made of a photodegradable resin containing a white pigment, and having a light reflecting function,
The light reflecting layer has a plurality of openings arranged in parallel in a stripe shape corresponding to 1: 1 for each of the plurality of unit lenses or unit prisms,
When the method forms the light reflecting layer,
Uniformly forming the photodegradable resin containing a white pigment on the other surface of the transparent support;
Irradiate light that causes photolysis from one surface side of the transparent support, and is a region on the other surface, where the light is condensed by the unit lens or the unit prism. Removing the photodegradable resin by exposure treatment;
And patterning the photodecomposable resin in a region other than the light condensing region on the other surface so as to remain without exposure.   The method for producing an optical sheet according to claim 9, wherein the transparent support is insoluble in a photodegradable resin solvent and a developer.

Images