JP5915309B2 - Backlight device and liquid crystal display device using the same - Google Patents

Description

  In particular, the present invention relates to a backlight device that is a small-sized backlight device such as a portable electronic device and has improved variations in color temperature of emitted white light and a liquid crystal display device using the backlight device.

  In recent years, liquid crystal display devices having features such as light weight, thinness, and low power consumption have been widely used as display devices for information devices such as personal computers and mobile phones, and display devices for video devices such as televisions, video movies, and car navigation systems. Yes.

  In such a liquid crystal display device, a configuration in which a backlight device for irradiating illumination light from behind the liquid crystal display panel is usually used is often used.

  Here, the backlight device used as a surface light source device is roughly classified into an edge light method and a direct light method depending on the location of the light source. For example, in the edge light system, a light emitting part is formed by arranging a plurality of LEDs or the like as point light sources on one end face of a light guide plate arranged opposite to a liquid crystal display panel, or a light emitting part of a tubular light source (fluorescent tube etc.) It is a method to arrange. The direct method is a method in which a plurality of straight tubular light sources such as fluorescent tubes are arranged on the back surface of the liquid crystal display panel, and a diffusion plate or the like is arranged between the liquid crystal display panel and the light source.

  Among these methods, the edge light method is particularly advantageous in terms of thinning, and can be said to be a method suitable for, for example, a display device of a small portable electronic device or a notebook personal computer.

  In such an edge light type backlight device, it is necessary to convert light from the light source into planar light, and therefore, a light guide plate for guiding the light incident from the light source is installed, and the light exit surface of the light guide plate is arranged. An optical sheet is placed on the backside, and a reflective sheet is placed on the back, which is the opposite side of the light exit surface, enabling conversion to planar light and improving brightness, directivity, light uniformity, etc. To be done.

  In general, a liquid crystal display device including an edge light type backlight device uses a light source disposed at an end portion of the backlight device as white light, and the white light is a color including a red colored layer, a green colored layer, and a blue colored layer. By passing through the filter, an image such as a desired character or video is displayed.

JP 2010-243960 A JP 2011-192468 A

  When using a white light emitting element that emits white light as a light source disposed at the end of the backlight device, the white light emitting element is usually formed by a combination of a blue LED that emits blue light and a phosphor, but the blue LED itself In addition, there is an individual difference in color temperature (for example, characteristic variation such as color temperature), and also an individual difference in color temperature is caused by quantitative variation of the formed phosphor and composition variation of the phosphor itself. That is, a double variation of color temperature variation caused by blue LEDs and color temperature variation caused by phosphors used in combination occurs.

  Such double color temperature variation can be said to be more uniform as the amount of the element emitting white light increases (the larger the screen), the less likely the problem occurs. In small-sized portable electronic devices with extremely small amounts, such as mobile products that can be operated with one hand (portable computer terminal devices including devices called so-called smartphones and iPhones), etc., there is a problem of variation in color temperature. It can happen that it cannot be ignored.

  Under such circumstances, the present invention has been invented, and the purpose of the present invention is to provide color even in a small portable electronic device that uses an extremely small amount of blue LED or the like that emits blue light. An object of the present invention is to provide an edge light type backlight device and a liquid crystal display device using the same which can improve the problem of temperature variation.

In order to solve the above-described problems, the present invention provides a backlight device having a light guide plate and a light source disposed at an end of the light guide plate, the light source having an element that emits blue light. The light guide plate contains phosphor fine particles that are excited by the blue light to convert the wavelength of the blue light , the light guide plate has a light incident surface and a light exit surface, and the light incident on the light guide plate An element emitting blue light is disposed on the surface side, a plurality of light extraction openings are formed on the light emission surface side of the light guide plate, and the area occupied by the light extraction opening as the distance from the light incident surface side of the light guide plate increases There have an area for increasing the surface portion other than the light outlet of the light emitting side of the light guide plate is configured so that the have a reflective film feature.

  As a preferred embodiment of the backlight device of the present invention, the phosphor fine particles are composed of a yellow phosphor.

  As a preferred embodiment of the backlight device of the present invention, the phosphor fine particles are composed of a red phosphor and a green phosphor.

As a preferred embodiment of the backlight device of the present invention, the yellow phosphor includes a YAG phosphor ((Y, Gd) ₃ Al ₅ O ₁₂ : Ce ³⁺ ), a silicate phosphor ((Sr, Ba) _2. SiO ₄ : Eu ²⁺ ), nitride phosphor ((Ca, Sr, Ba) AlSiN ₃ : Eu ²⁺ ), oxynitride phosphor (Ba ₃ Si ₆ O ₁₂ N ₂ : Eu ²⁺ ) 1 type is comprised.

In a preferred embodiment of the backlight device of the present invention, the red phosphor is M ₂ O ₂ S: Eu ²⁺ (where M is one or more elements selected from La, Gd, and Y) ), 0.5 MgF ₂ .3.5MgO.GeO ₂ : Mn ²⁺ , Y ₂ O ₃ : Eu ²⁺ , Y (P, V) O ₄ : Eu ²⁺ , YVO ₄ : Eu ²⁺ 1 type, and the green phosphor is RMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ (where R is one or both elements selected from Sr and Ba), RMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ (wherein R is one or both elements selected from Sr and Ba), ZnS: Cu ²⁺ , SrAl ₂ O ₄ : Eu ²⁺ , SrAl ₂ O ₄ : Eu ²⁺ , Dy ²⁺ , ZnO: Zn ²⁺ , Zn ₂ Ge ₂ O ₄ : Mn ²⁺ , Zn ₂ SiO ₄ : Mn ²⁺ , Q ₃ Mg Si ₂ O ₈ : Eu ²⁺ , Mn ²⁺ (where Q is any one or more elements selected from Sr, Ba, and Ca).

  Moreover, as a preferable aspect of the backlight device of the present invention, the element emitting blue light is a blue LED, and the number of blue LEDs arranged at the end of the light guide plate is 4 to 50. Is done.

  Moreover, as a preferable aspect of the backlight device of the present invention, the phosphor fine particles are uniformly dispersed inside the light guide plate.

  Moreover, the backlight apparatus of this invention is comprised as an edge light system as a preferable aspect.

  Moreover, as a preferable aspect of the backlight device of the present invention, an optical sheet is disposed on the light exit surface side of the light guide plate, and a reflective film is disposed on the back side opposite to the light exit surface of the light guide plate. Composed.

  The liquid crystal display device of the present invention is a liquid crystal display device having the backlight device described above and a liquid crystal display panel, and the liquid crystal display panel includes a color filter substrate and a display array substrate. It is comprised so that it may become.

  The backlight device of the present invention is a backlight device having a light guide plate and a light source disposed at an end of the light guide plate, the light source having an element that emits blue light, and the light guide plate Since it is configured to contain phosphor fine particles that are excited by the blue light and convert the wavelength of the blue light, a small-sized portable device that uses an element that emits the blue light provided in the light source is extremely small In the electronic equipment for use etc., the problem of variation in the color temperature of the white light emitted from the light exit surface of the light guide plate can be improved.

FIG. 1 is an exploded perspective view showing an example of a backlight device used in the liquid crystal display device of the present invention. FIG. 2 is a plan view taken along the line α-α shown in FIG. 1 and shows a configuration of a main part of a light source of the backlight device. FIG. 3 is a plan view similar to FIG. 2, and is a plan view showing a modification of the main configuration of the light source of the backlight device. FIG. 3 is a cross-sectional view taken along the line β-β in FIG. 2. FIG. 5 is a plan view of the light guide plate viewed from the light exit surface side. FIG. 6 is a cross-sectional view for explaining an example of a color filter substrate and a display array substrate for constituting a liquid crystal display device. FIG. 7 is a partial cross-sectional view of a display device formed by combining a color filter substrate, a display array substrate, and a backlight device. However, the backlight device is not shown in a sectional view. FIG. 8 is a plan view for explaining the configuration of the pixel portion of the color filter substrate.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the form demonstrated below, In the range which does not deviate from a technical thought, it can implement in various deformation | transformation. In the accompanying drawings, the scales of the top, bottom, left and right are sometimes exaggerated for easy understanding, and the scales may differ from the actual ones.

  A backlight device according to a preferred embodiment of the present invention and a liquid crystal display device using the same will be described with reference to FIGS.

  As shown in FIG. 7, the liquid crystal display device 1 of the present invention includes a liquid crystal display panel 150 and a backlight device 200, and the liquid crystal display panel 150 includes a color filter substrate 30 and a display device. It has an array substrate 100 and a liquid crystal part 140.

Hereinafter, these components will be described in detail.
First, the backlight device 200 of the present invention will be described with reference to FIGS.

<Backlight device 200>
FIG. 1 is an exploded perspective view showing an example of a backlight device 200 used in the liquid crystal display device 1 of the present invention. FIG. 2 is a plan view taken along the line α-α shown in FIG. 1 and shows a configuration of a main part of a light source of the backlight device. FIG. 3 is a plan view showing a modification of FIG. 4 is a cross-sectional view taken along the line β-β of FIG. 2, and FIG. 5 is a plan view of the backlight device 200 as viewed from the light exit surface side. FIG. 5 is a plan view of an example in which a pair of light sources are arranged to face each other so as to sandwich a light guide plate.

  As shown in FIG. 1, the backlight device 200 includes a light guide plate 210 and a light source 220 disposed at an end of the light guide plate 210.

  The light guide plate 210 has a substantially quadrangular flat plate shape, and in the drawing, an upper surface 210b that is an upper main plane, a lower surface 210c that is a lower main plane, and a periphery of the upper surface 210b and the lower surface 210c. Are connected to each other. In the present embodiment, one end surface 210a of the light guide plate, which is one of the four side surfaces, constitutes the light incident surface 210a, and the light source 220 is introduced so that light is introduced into the light incident surface 210a. Is arranged. With such an arrangement, a so-called edge light type backlight device can be formed. In the configuration example in FIG. 1, a reflective film may be provided on three side surfaces excluding the light incident surface 210a.

  In addition, as shown in FIG. 5, a light source 220 may be provided on the opposite surface 210 d side opposite to the light incident surface 210 a, and light may be further incident from the opposite surface 210 d side facing the light source 220. .

  As shown in FIG. 1, a reflection sheet 260 is usually provided on the lower surface 210c of the light guide plate 210, and an optical sheet 250 is usually provided on the upper surface 210b (light emission surface 210b) of the light guide plate 210. The light guide plate 210, the light source 220, the optical sheet 250, the reflection sheet 260, and the like are accommodated in a thin box-like back case 270 made of, for example, metal.

  The light source 220 and the light guide plate 210 constituting the backlight device 200 of the present invention will be further described.

(light source)
As shown in FIGS. 1 to 2, the light source 220 in the present invention includes, for example, a long substrate 221 and a blue light emitting unit 240 </ b> B that emits blue light formed on the main surface of the substrate 221. It is a module type light source configured to have. Such a light source 220 normally faces the light incident surface 210a, which is one side end surface 210a of the light guide plate 210, so that light is introduced into the light incident surface 210a so as to be substantially parallel to the light incident surface 210a. It is desirable to be arranged.

  Of course, as described above, the light source 220 may be disposed on both side end faces 210a and 210d which are parallel to each other of the light guide plate 210 (see FIG. 5).

  The blue light emitting unit 240B, which is one element constituting the light source 220, includes an element 241 that emits blue light, such as a blue LED, and a sealing body 242. The sealing body 242 is preferably composed of a light-transmitting material such as a transparent resin or a transparent inorganic material. Note that the substrate 221 may be formed of a material that can hold the element 241 that emits blue light and the sealing body 242, and is not particularly limited. Further, the substrate 221 may be omitted.

  For example, a suitable specific example of the blue light emitting unit 240B is exemplified. For example, a GaN-based blue LED is used as the element 241 that emits blue light, and a silicone resin that covers the element 241 that emits blue light is used as the sealing body 242. For example, a light-transmitting material is used. However, the present invention is not limited to such a specific example, and the blue light emitting unit 240B that can emit blue light may be configured by a configuration other than the above.

  The number of the elements 241 that emit blue light is in the range of 4 to 50, preferably in the range of 4 to 25, more preferably in the range of 4 to 15, and the preferred use of the present invention. It becomes an aspect. This is because it is an object of the present invention to improve the problem of color temperature variation that can be particularly noticeable in small portable electronic devices and the like in which the number of light emitting elements used is small.

(Light guide plate 210)
The light guide plate 210 constituting the backlight device 200 of the present invention includes a transparent resin that is a matrix (base material) and phosphor fine particles that exist in a dispersed state in the resin. As the transparent resin which is a matrix (base material), a material such as a polycarbonate resin and an acrylic resin which are excellent in transparency and good in light transmittance can be used.

  The phosphor fine particles are a material that is excited by the blue light emitted from the blue light emitting element 241 and converts the wavelength of the blue light. Here, “phosphor fine particles that are excited by blue light and convert the wavelength of blue light” means that by irradiating the phosphor with blue light, the electrons of the phosphor that absorbed energy are excited, This means “phosphor fine particles” that can release excess energy as light having a longer wavelength than blue light when returning to the ground state.

  The phosphor fine particles to be used obtain white light by mixing the fluorescence emitted from the phosphor fine particles by irradiating the phosphor fine particles with the blue light emitted from the light source and the blue light transmitted (or reflected) through the phosphor fine particles. It may be selected as appropriate.

  Specifically, examples of the phosphor fine particles include (1) using a yellow phosphor material, or (2) using both a red phosphor material and a green phosphor material. Preferably, a yellow phosphor material that can be composed of one kind of material is used because the optical characteristics can be easily adjusted.

(1) When a yellow phosphor material is used, examples of the yellow phosphor include YAG phosphor ((Y, Gd) ₃ Al ₅ O ₁₂ : Ce ³⁺ ), silicate phosphor ((Sr, Ba) ₂ SiO ₄ : Eu ²⁺ ), nitride phosphor ((Ca, Sr, Ba) AlSiN ₃ : Eu ²⁺ ), oxynitride phosphor (Ba ₃ Si ₆ O ₁₂ N ₂ : Eu ²⁺ ) However, it is not necessarily limited to these.

  The size of such yellow phosphor fine particles is 1.0 to 50 μm, preferably 2.0 to 48 μm, and more preferably about 2.5 to 45 μm. When this value is less than 1.0 μm, the volume fraction of lattice defects existing on the crystal surface of the phosphor increases, the recombination of electrons and holes is inhibited, and the rate of heat loss without light emission increases. As a result, there is a tendency that inconvenience that the luminous efficiency is lowered tends to occur, and when this value exceeds 50 μm, there is a tendency that a sufficient surface area cannot be secured per unit weight of the powder and luminance is lowered. .

  It is desirable that the yellow phosphor fine particles contained in the matrix (base material) be contained as uniformly dispersed as possible. The uniform dispersion as used in the present invention includes all aspects except when intentionally creating a non-uniform state. In the present invention, the degree of dispersion within an error range of ± 20% with respect to the average value is defined as uniform dispersion.

  The content of the yellow phosphor fine particles may be appropriately selected so that white light having a desired color temperature can be obtained in consideration of the size of the yellow phosphor fine particles to be used. The content is usually about 5 to 40 Vol% (volume%).

(2) When both the red phosphor material and the green phosphor material are used, suitable red phosphors include M ₂ O ₂ S: Eu ²⁺ (where M is from La, Gd, Y) Any one or two or more selected elements), 0.5 MgF ₂ .3.5MgO.GeO ₂ : Mn ²⁺ , Y ₂ O ₃ : Eu ²⁺ , Y (P, V) O ₄ : Eu ²⁺ , YVO ₄ : Eu ²⁺ and a suitable green phosphor, RMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ (where R is Sr , Ba or any element selected from Ba), RMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ (where R is any one or both elements selected from Sr and Ba), ZnS: Cu ²⁺ , SrAl ₂ O ₄ : Eu ²⁺ , SrAl ₂ O ₄ : Eu ²⁺ , Dy ²⁺ , ZnO: Zn ²⁺ , Zn ₂ Ge ₂ O ₄ : Mn ²⁺ , Zn ₂ SiO ₄ : Mn ²⁺ , Q ₃ MgSi ₂ O ₈ : Eu ²⁺ , Mn ²⁺ (wherein Q is any one selected from Sr, Ba, Ca or 1 type selected from 2 or more elements) can be comprised. However, it is not limited to the combination of the above materials.

  The size of the fine particles of the red phosphor is 1.0 to 50 μm, preferably 2.0 to 48 μm, and more preferably about 2.5 to 45 μm. The size of the green phosphor fine particles is 1.0 to 50 μm, preferably 2.0 to 48 μm, and more preferably about 2.5 to 45 μm. The reason for the inconvenience when the upper limit value and the lower limit value are exceeded in the fine particles of these phosphors is the same as the reason for the inconvenience in the case of the above-mentioned yellow phosphor fine particles.

  It is desirable that the red phosphor fine particles and the green phosphor fine particles contained in the matrix (matrix) are contained in a state of being dispersed as uniformly as possible. The uniform dispersion as used in the present invention includes all aspects except when intentionally creating a non-uniform state.

  The content of each of the red phosphor fine particles and the green phosphor fine particles may be appropriately selected so that white light having a desired color temperature can be obtained in consideration of the sizes of the red phosphor fine particles and the green phosphor fine particles to be used. Good. The content is usually about 5 to 40 Vol% (volume%).

  Although not shown, a dot pattern of minute protrusions for diffusing reflected light on the lower surface 210c may be formed on the lower surface 210c of the light guide plate 210. In general, the light guide plate 210 is prepared to a predetermined size by preparing a resin raw material containing phosphor fine particles and using the resin raw material by an extrusion molding method, an injection molding method, or the like. When the extrusion molding method is used, the light guide plate 210 is usually manufactured by punching a molded sheet body into a predetermined size.

  A plurality of light extraction ports 230 as shown in FIG. 5 may be formed on the light exit surface 210 b side of the light guide plate 210. The surface portion 235 other than the light extraction port 230 (particularly the back side of the paper surface) is configured to act as a reflective film.

  As shown in FIG. 5, the light extraction port 230 is formed with circular light extraction ports 231, 232, 233, and 234 that gradually increase as the distance from the light incident surface 210 a side and 210 d side of the light guide plate 210 increases. As a result, areas E1 and E2 in which the area occupied by the light extraction port gradually increases are formed. By setting it as such a structure, the light quantity inject | emitted from the light-projection surface 210b side of the light-guide plate 210 can be substantially made uniform.

  Whether or not the areas E1 and E2 shown in FIG. 5 correspond to the areas where the occupied area of the light extraction port according to the present invention gradually increases is determined based on the areas of the areas E1 and E2 in the light guide directions y1 and y2. It may be determined by dividing into two equal parts by lines x1 and x2 (indicated by dotted lines in FIG. 5) perpendicular to the two and comparing the occupied areas of the light extraction ports in the two divided areas.

  The shape of the light extraction port 230 is preferably circular as shown in FIG. 5, but is not limited to this shape. A polygon other than a circle or an ellipse can also be used. Further, instead of sequentially changing the size of the light extraction port 230, the arrangement density may be sequentially increased with the opening shape having the same size.

  5 shows an example in which the light sources 220 are arranged at both ends of the light guide plate 210. However, when the light source 220 is arranged only at one end (for example, see FIG. 1), the areas E1, E1 shown in FIG. Of course, any one of E2 may be provided.

  When a plurality of light extraction openings 230 as shown in FIG. 5 are provided, the light extraction openings 230 and the surface portion 235 having a reflective film function are formed directly on the light emission surface 210b side of the light guide plate 210 using photolithography or the like. Alternatively, a sheet material including a light extraction port 230 and a surface portion 235 having a reflective film function may be formed in advance, and the sheet material may be attached to the light emission surface 210b side of the light guide plate 210. You may make it attach.

Next, another configuration of the backlight device 200 will be described.
(Optical sheet)
The optical sheet 250 is disposed on the light exit surface 210b side of the light guide plate 210, and usually has a plurality of unit prisms. The optical sheet is used to change the traveling direction of the light incident on the light guide plate 210 from the light incident surface 210a to be emitted from the light emitting surface 210b, and to intensively improve luminance and the like. As such an optical sheet 250, a general sheet used in a liquid crystal display device can be used. Various known forms can be adopted for the cross-sectional shape, protrusion height, bottom width, apex angle, etc. of the unit prism.

  The material of the optical sheet 250 is not particularly limited as long as an optical sheet having a plurality of unit prisms can be produced. For example, polycarbonate resin, ABS (acrylonitrile-butadiene-styrene copolymer) resin, methacrylic resin can be used. Examples thereof include resins, methyl methacrylate-styrene copolymer resins, polystyrene resins, acrylonitrile-styrene copolymer resins, polyethylene resins, and polypropylene resins.

  What is necessary is just to adjust the thickness of an optical sheet suitably, for example, it can be set as about 5 micrometers-100 micrometers. As a method for producing the optical sheet, a general method can be used. For example, the optical sheet is pressed against the surface of the ultraviolet curable resin by using a mold having a shape corresponding to the unit prism on the surface, and then ultraviolet rays are used. Examples include a curing method.

(Reflective sheet)
The reflection sheet 260 is disposed on the lower surface 210 c that is the back surface of the light guide plate 210. The reflection sheet 260 is used to reflect light traveling toward the back surface of the light guide plate 210 and enter the light guide plate 210 again. As the reflection sheet 260, a general reflection sheet can be used. For example, a white scattering reflection sheet, a sheet made of a material having a high reflectance such as metal, a thin film made of a material having a high reflectance (for example, a metal) The sheet | seat etc. which equip a part with a thin film can be mentioned.

  Specific examples of the material of the reflection sheet 260 include resins such as polyethylene terephthalate (PET (white PET)), polycarbonate (PC), polystyrene, and polyolefin, and metals such as aluminum and silver. Moreover, when using resin for the reflective sheet 260, in order to improve reflectivity, it is preferable to set it as the white sheet | seat containing a pigment. Examples of the pigment to be included include titanium dioxide, barium sulfate, magnesium carbonate, and calcium carbonate. When a metal thin film is provided on a part of the reflection sheet 260, a metal film having a high reflectance such as silver, aluminum, or chromium may be formed by a vapor deposition method, a sputtering method, a CVD method, or the like. A commercially available product may be used as the reflection sheet 260. Examples of commercially available products include (Vicuity) ESR reflective film manufactured by Sumitomo 3M Limited, E60V manufactured by Toray Industries, Inc., and the like. When such a commercial product is used, the light guide plate 210 and the reflective sheet 260 may be bonded together by interposing a resin having a refractive index matched.

  The thickness of the reflection sheet is not particularly limited and may be adjusted as appropriate, and can be, for example, about 30 μm to 300 μm.

(Other configurations around the backlight device 200)
In the present invention, although not shown, a diffusion sheet having a function of diffusing transmitted light or a polarized light reflection function having a polarization separation function by transmitting only a specific polarization component and reflecting other polarization components. A sheet or the like may be provided on the light exit surface side of the optical sheet 250.

  The diffusion sheet is a member having a function of diffusing light emitted from the optical sheet to reduce luminance unevenness. As the diffusion sheet, a general sheet used in a liquid crystal display device can be used. Examples of the material of the diffusion sheet include methyl methacrylate styrene copolymer, acrylonitrile styrene copolymer, polycarbonate (PC), polyethylene terephthalate (PET), polystyrene, and the like. Further, the diffusion sheet may contain particles. Examples of the particles include inorganic particles such as silica and alumina, fluorine resin particles such as acrylic resin, styrene resin, polytetrafluoroethylene, and polyfluorovinylidene, and silicone resin particles. These particles can be used alone or in combination of two or more. The average particle diameter of the particles is preferably in the range of 0.3 μm to 2.0 μm from the viewpoint of scattering properties. The content of the particles may be adjusted as appropriate. The thickness of the diffusion sheet can be, for example, about 5 μm to 100 μm.

  The polarization reflection sheet is a member having a polarization separation function that transmits only a specific polarization component of light emitted from the optical sheet 250 and reflects other polarization components. In a liquid crystal display device, when a polarizing plate is provided between the liquid crystal cell and the polarizing reflection sheet, the polarizing plate selectively transmits only a specific polarization component. By selectively reflecting and reusing other polarization components, the amount of light passing through the polarizing plate can be substantially increased and the luminance can be improved.

  As the polarizing reflection sheet, a general sheet used in a liquid crystal display device can be used. Commercially available products may be used as the polarizing reflection sheet, and for example, DBEF series manufactured by Sumitomo 3M Limited can be used.

  Further, a heat sink for releasing the heat generated from the light source may be formed.

Next, the color filter substrate 30 will be described.
<Color filter substrate 30>
As described in the upper side of FIG. 6, the color filter substrate 30 used in the liquid crystal display device 1 of the present invention includes a transparent substrate 10 and a pixel component layer that is a pixel portion formed on the transparent substrate 10. 13 and a light shielding portion 12 formed around the pixel configuration layer 13. In general, if attention is paid to most of the other pixel configuration layers 13 excluding the pixel configuration layer 13 disposed on the outermost periphery of the substrate, the light shielding portion 12 exists in the gap portion between the adjacent pixel configuration layers 13. To do.

  The transparent substrate 10 is not particularly limited as long as it is a substrate transparent to visible light, and the same transparent substrate used for a general color filter can be used. Specifically, a rigid material such as quartz glass, Pyrex (registered trademark) glass, or synthetic quartz, or a transparent flexible material having flexibility such as a transparent resin film or an optical resin plate can be used.

  The pixel constituting layer 13 in the color filter substrate 30 used in the present invention includes a red colored layer 13R, a green colored layer 13G, and a blue colored layer 13B as shown in FIGS. A pattern is formed in an arrayed state. However, the pattern arrangement is not particularly limited to that shown in the drawings, and can be a known arrangement such as a stripe type, a mosaic type, a triangle type, a four-pixel arrangement type, and the area of each colored layer is arbitrarily set. Can be set.

  Each of the red colored layer 13R, the green colored layer 13G, and the blue colored layer 13B formed on the color filter substrate 30 according to color characteristics of white light emitted from the backlight device 200, that is, chromaticity and luminance. The area ratio (pixel aperture ratio) can be set as appropriate.

  It should be noted that the number of pixel configuration layers 13 (number of pixels), which is a pixel portion in the drawings, is described only as an example, and is not limited to the illustrated example. As a method for forming the pixel configuration layer 13, a method for forming the pixel configuration layer 13 in a general color filter, for example, a photolithography method, an inkjet method, a printing method, or the like may be used.

  Examples of the coloring material used for the red colored layer 13R include perylene pigments, lake pigments, azo pigments, quinacridone pigments, anthraquinone pigments, anthracene pigments, and isoindoline pigments. These pigments may be used alone or in combination of two or more.

  Examples of coloring materials used for the green colored layer 13G include phthalocyanine pigments such as halogen polysubstituted phthalocyanine pigments or halogen polysubstituted copper phthalocyanine pigments, triphenylmethane basic dyes, isoindoline pigments, and isoindolinone. And pigments. These pigments or dyes may be used alone or in combination of two or more.

  Examples of the coloring material for forming the blue colored layer 13B include copper phthalocyanine pigments, anthraquinone pigments, indanthrene pigments, indophenol pigments, cyanine pigments, dioxazine pigments, and the like. These pigments may be used alone or in combination of two or more.

  Examples of the binder resin used when forming each of the pixel constituent layers 13 include a copolymer of benzyl methacrylate: styrene: acrylic acid: 2-hydroxyethyl methacrylate. Solvents include benzene, toluene, xylene, n-butylbenzene, diethylbenzene, tetralin and other hydrocarbons, methoxybenzene, 1,2-dimethoxybenzene, diethylene glycol dimethyl ether and other ethers, acetone, methyl ethyl ketone, methyl isobutyl ketone. , Ketones such as cyclohexanone and 2,4-pentanedione, ethyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, esters such as g-butyrolactone, 2-pyrrolidone, N- Amide solvents such as methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, chloroform, dichloromethane, carbon tetrachloride, dichloro Halogen solvents such as ethane, tetrachloroethane, tritrichloroethylene, tetrachloroethylene, chlorobenzene, orthodichlorobenzene, t-butyl alcohol, diacetone alcohol, glycerin, monoacetin, ethylene glycol, triethylene glycol, hexylene glycol, ethylene glycol monomethyl ether, ethyl One type or two or more types of alcohols such as cellsolve and butylcellsolve and phenols such as phenol and parachlorophenol can be used. If only one type of solvent is used, the solubility of the coating composition may be insufficient, or the material that forms the coating partner when the coating composition is applied (the material constituting the substrate) may be affected. In the case where there is, for example, these disadvantages can be avoided by using a mixture of two or more solvents.

  Moreover, you may make it contain surfactants, such as a fluorosurfactant and a nonionic surfactant, as needed.

  The light-shielding portion 12 (sometimes referred to as a so-called black matrix) in the present embodiment is desirably formed, but is not indispensable for exhibiting the effects of the present invention. The light shielding portion 12 is usually configured as a lattice-shaped light shielding layer, and is usually configured using a photoresist, a printing ink, or a metal such as chromium containing a black pigment, a binder resin, and a solvent. Examples of black pigments used in printing inks include carbon black and titanium black. Examples of binder resins include benzyl methacrylate: styrene: acrylic acid: 2-hydroxyethyl methacrylate copolymer. The solvent can be selected from various known solvents. As a method for forming the light shielding portion 12, it can be formed by a photolithography method, various pattern printing methods, various plating methods, and the like.

  As shown in FIG. 6, the transparent electrode layer 18 is formed so as to cover the pixel constituting layer 13 having the red colored layer 13R, the green colored layer 13G, and the blue colored layer 13B. Examples of the material for forming the transparent electrode layer 18 include a metal oxide having transparency and conductivity. Examples of such a metal oxide include indium tin oxide (ITO), indium oxide, zinc oxide, and stannic oxide. The film thickness of the transparent electrode layer 18 is 50 nm to 1500 nm, and more preferably 120 nm to 1200 nm.

  As a method for forming the transparent electrode layer 18, for example, a vapor deposition method or a sputtering method may be used. An overcoat layer (protective film) or the like may be formed before forming the transparent electrode layer 18.

[Description of the display array substrate 100]
Next, the display array substrate 100 (liquid crystal display substrate) will be described with reference to FIG.

  The display array substrate 100 shown on the lower side of FIG. 6 is disposed so as to face the color filter substrate 30 described above, and is integrated to form a display device. In FIG. 6, the color filter substrate 30 arranged to face is also described. The color filter substrate 30 shown in FIG. 6 is formed on the alignment electrode 18 on the transparent electrode layer 18 in order to form a display device. The state in which 20 is formed is depicted. The alignment film 20 is usually provided at the time of the next cell combination step for completing the manufacturing process of the color filter substrate 30 and forming a display device.

  As shown in FIG. 6, the display array substrate 100 is configured by a scanning line (not shown), an interlayer insulating film 60, and a large number of pixel electrodes 65a arranged in a matrix on a light-transmitting substrate 55. A structure having a transparent electrode 65, a signal line 70, a protective film (passivation film) 75, a switching circuit portion (not shown), and an alignment film 80 is provided.

  Although the scanning lines are not displayed in the drawing, for example, the scanning lines are arranged so as to correspond to one row (a horizontal direction in the drawing) of a large number of pixel electrodes 65a arranged in a matrix. It is comprised so that it may extend in the longitudinal direction. Each scanning line can be formed of a metal such as tantalum (Ta) or titanium (Ti), for example. These scanning lines are covered with an interlayer insulating film 60.

  The interlayer insulating film 60 is formed of an electrically insulating material such as silicon oxide, for example, and electrically separates the scanning line and the signal line 70 and electrically connects the pixel electrode 65a and the scanning line. It is formed to separate.

  Each pixel electrode 65a is formed so as to correspond to one pixel portion in the display device. Examples of the material for forming the pixel electrode 65a include a metal oxide having transparency and conductivity. Examples of such a metal oxide include indium tin oxide (ITO), indium oxide, zinc oxide, and stannic oxide. The film thickness of the formed electrode layer is 50 nm to 1500 nm, more preferably 120 nm to 1200 nm. As a method for forming the pixel electrode 65a, for example, an evaporation method or a sputtering method may be used. The shape of each pixel electrode 65a in plan view can be, for example, a quadrilateral or a polygon such as a hexagon formed by cutting one corner of the quadrilateral into a rectangle, but is not necessarily limited to these shapes. It is not something.

  For example, the signal lines 70 are arranged so as to correspond to one column (in the direction of the back side of the paper surface) of a large number of pixel electrodes 65a arranged in a matrix and extend in the longitudinal direction of the column. Configured as follows. Each signal line 70 can be formed of a metal such as tantalum (Ta) or titanium (Ti). These signal lines 70 are covered with a protective film 75.

  The protective film 75 is made of, for example, silicon nitride, and functions as a protective film of the main body and acts to electrically separate the signal line 70 and the pixel electrode 65a.

  Although the switching circuit section is not shown in FIG. 6, the switching circuit section is arranged corresponding to one pixel electrode 65a one by one, and the pixel electrode 65a corresponding to the switching circuit section, the scanning line, and the signal line 70 is electrically connected.

  Each switching circuit unit receives a signal from a corresponding scanning line and controls conduction between the signal line 70 and the pixel electrode 65a. Each switching circuit unit can be configured using, for example, an active element. As the active element, for example, a three-terminal element such as a thin film transistor (TFT) or a two-terminal element such as a MIM (Metal Insulator Metal) diode is used, but is not necessarily limited thereto.

  The alignment film 80 can be configured as a horizontal alignment film that can horizontally align the liquid crystal in the display device, or a vertical alignment film that can vertically align the liquid crystal. Which of the horizontal alignment film and the vertical alignment film is used can be appropriately selected according to the operation mode of the display device. The alignment film 80 formed on the display array substrate 100 side can have the same configuration as the alignment film 20 formed on the color filter substrate 30 side.

  For the display array substrate 100 used in the liquid crystal display device 1 of the present invention, the color filter substrate 30 is usually formed by a so-called surface division method which is performed using a backlight device having only a light source that emits white light. A control function unit for displaying the color of the pixel configuration layer 13 is connected.

[Configuration of liquid crystal display device]
As described above, the color filter substrate 30 on which the alignment layer 20 is formed and the display array substrate 100 on which the alignment layer 80 is formed have the alignment layer 20 and the alignment layer 80 facing each other as shown in FIG. In a state where a predetermined gap is provided, the sealing material (for example, thermosetting resin) 90 is bonded together leaving a filling port for filling the liquid crystal material.

  The gap (cell gap) between the display array substrate 100 and the color filter substrate 30 is kept constant by a spacer (for example, a spherical spacer or a columnar spacer) not shown, and the gap between the two is provided from the filling port. A liquid crystal layer 91 is formed by filling the liquid crystal material. The filling port after liquid crystal filling is sealed. Then, as shown in FIG. 7, the backlight device 200 as a light source is disposed behind the light transmissive substrate 55 of the display array substrate 100 to form the liquid crystal display device 1.

  Although not shown, normally, polarizing plates are bonded to the outer surfaces of the display array substrate 100 and the color filter substrate 30 with their polarization axes orthogonal to each other.

  The present invention will be described in more detail with reference to specific examples below, but the present invention is not construed as being limited to the following examples.

[Example 1]
(Preparation of color filter substrate 30)
As the substrate, a glass substrate (Corning 1737 glass) having a plane size of 370 mm × 470 mm and a thickness of 0.7 mm was prepared.

  After washing this substrate in accordance with a conventional method, a negative photosensitive resist (CFPR DN-83 manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied, exposed through a predetermined mask, developed, and baked to form a light shielding portion 12. A black matrix was formed.

  Next, a negative photosensitive resin composition for red pattern for forming the red colored layer 13R shown below, a negative photosensitive resin composition for green pattern for forming the green colored layer 13G, and blue A negative photosensitive resin composition for a transparent uncolored pattern for forming the colored layer 13B was prepared.

<Negative photosensitive resin composition for red pattern>
・ Red pigment (Chromophthal red A2B manufactured by Ciba Specialty Chemicals) ... 2.0 parts by weightRed pigment (Chromophthalred BP manufactured by Ciba Specialty Chemicals) ... 1.0 parts by weight Dispersic 161) ... 1.5 parts by weight Monomer (SR399, manufactured by Sartomer) 4.0 parts by weight Polymer I ... 5.0 parts by weight Initiator (Irgacure 907, manufactured by Ciba Specialty Chemicals) 1 .4 parts by weight Initiator (2,2′-bis (o-chlorophenyl) -4,5,4 ′, 5′-tetraphenyl-1,2′-biimidazole)... 0.6 parts by weight Solvent ( Propylene glycol monomethyl ether acetate) ... 80.0 parts by weight

<Negative photosensitive resin composition for green pattern>
Green pigment (Daiichi Seika Co., Ltd., Cyanine Green 5370) ... 1.2 parts by weight Green pigment (Daiichi Seika Co., Ltd., Cyanine Green 2GN) ... 1.6 parts by weightYellow pigment (Lanxess Byplast Yellow 5GN01) 1.2 parts by weight Dispersant (Disperbic 161 manufactured by Big Chemie) ... 2.0 parts by weight Monomer (SR399 manufactured by Sartomer) ... 4.0 parts by weight Polymer I ... 5.0 parts by weight Initiator (Ciba・ Specialty Chemicals Irgacure 907) 1.4 parts by weight ・ Initiator (2,2′-bis (o-chlorophenyl) -4,5,4 ′, 5′-tetraphenyl-1,2′-bi Imidazole) ... 0.6 parts by weightSolvent (propylene glycol monomethyl ether acetate) ... 80.0 parts by weight

<Negative photosensitive resin composition for blue pattern>
・ Purple pigment (trade name Novotex Violet BL-PC VP2429, manufactured by Clariant) ... 0.6 parts by weightBlue pigment (Heliogen Blue L6700F, manufactured by BASF) ... 1.4 parts by weightPigment derivative (Solsperse 5000, manufactured by Avicia) ... 0.2 parts by weight Dispersant (Disperbic 161 manufactured by Big Chemie) ... 0.8 parts by weight Monomer (SR399 manufactured by Sartomer) ... 4.0 parts by weight Polymer I ... 5.0 parts by weight Initiator ( Ciba Specialty Chemicals Irgacure 907) 1.4 parts by weight Initiator (2,2'-bis (o-chlorophenyl) -4,5,4 ', 5'-tetraphenyl-1,2'- Biimidazole) ... 0.6 parts by weightSolvent (propylene glycol monomethyl ether acetate) ... 80.0 parts by weight

  The polymer I is based on 100 mol% of a copolymer of benzyl methacrylate: styrene: acrylic acid: 2-hydroxyethyl methacrylate = 15.6: 37.0: 30.5: 16.9 (molar ratio). 2-methacryloyloxyethyl isocyanate was added at 16.9 mol%, and the weight average molecular weight was 42500.

  Next, a negative photosensitive resin composition for red pattern is applied by spin coating so as to cover the black matrix on the glass substrate, and is exposed, developed, and baked through a photomask for red pattern. A red pattern was formed. Thereafter, using the negative photosensitive resin composition for green pattern and the negative photosensitive resin composition for blue pattern, a green pattern and a blue pattern were sequentially formed by the same operation as the above red pattern formation. . Thereby, a pixel configuration layer in which a red pattern, a green pattern, and a blue pattern were arranged was formed. The arrangement was as shown in FIG.

  Next, the following protective film composition was applied as a color filter protective film composition onto the glass substrate on which each of the pixel constituent layers was formed by a spin coating method.

<Composition of composition for protective film>
・ Methyl methacrylate-styrene-acrylic acid copolymer: 32 parts by weight ・ Epicoat 180S70 (manufactured by Japan Epoxy Resin Co., Ltd.) ... 18 parts by weight ・ Dipentaerythritol pentaacrylate: 42 parts by weight ・ Initiator (Ciba Specialty Chemicals) Irgacure 907) ... 8 parts by weight 3-methoxybutylacetate ... 300 parts by weight Next, after exposing and developing through a photomask and baking to form a protective film, a transparent electrode layer is formed thereon. Then, a color filter substrate was produced.

(Production of backlight device 200)
A backlight device 200 as shown in FIG. 1 was produced.
The light guide plate 210 has a vertical x horizontal dimension of 300 (mm) x 400 (mm).
A polycarbonate resin is used as a matrix (base material), and 25 fine particles (average particle diameter: 22 μm) of YAG phosphor ((Y, Gd) ₃ Al ₅ O ₁₂ : Ce ³⁺ ), which is a yellow phosphor, are contained in this resin. A light guide plate 210 having the above size was produced by injection molding using pellets produced by kneading at a volume percentage.

  As shown in FIGS. 1 and 2, the light source 220 is formed by arranging and forming a total of ten blue light emitting portions 240B that emit blue light on an acrylic substrate.

  The blue light emitting portion 240B is formed of a GaN-based LED light emitting element that emits blue light and a sealing body made of a silicone resin that is a translucent material.

  A white polyester film having a thickness of 250 μm was disposed on the back surface of the light guide plate 210 as the reflection sheet 260.

  As the optical sheet 250, an optical sheet as a so-called prism sheet is disposed on the light exit surface side of the light guide plate. The optical sheet (prism sheet) was produced by forming a plurality of unit prisms on a 125 μm thick polyester film using an acrylic ultraviolet curable resin.

(Production of display array substrate 100)
Next, the display array substrate 100 that is paired with the color filter substrate 30 was fabricated as follows.

First, as a substrate, a glass substrate (Corning 1737 glass) having a size of 370 mm × 470 mm and a thickness of 0.7 mm was prepared.
In accordance with a conventional method, a display array substrate 100 was manufactured in which the current flowing through the element of the light emitting portion arranged for each pixel can be controlled by a TFT (Thin Film Transistor) in the drive circuit provided for each element.

(Production of liquid crystal display device 1)
As shown in FIG. 7, the color filter substrate 30 on which the alignment layer 20 is formed and the display array substrate 100 on which the alignment layer 80 is formed are arranged to face each other with a predetermined gap therebetween. The material was filled with a sealant 90 in a state of being filled.

  Thereafter, as shown in FIG. 7, the backlight unit 200, which is a light source, is disposed behind the light-transmitting substrate 55 of the display array substrate 100, thereby manufacturing the liquid crystal display device 1 of the present invention.

[Comparative Example 1]
The light guide plate 210 of the backlight device 200 used in Example 1 was changed to a simple polycarbonate resin not containing phosphor fine particles. Further, the blue light emitting unit 240B of the light source 220 is changed to a white light emitting unit that emits white light having the following configuration. That is, the white light emitting part that emits white light is composed of a GaN-based LED light emitting element that emits blue light, a YAG phosphor ((Y, Gd) ₃ Al ₅ O ₁₂ : Ce ³⁺ ), and a translucent material. It formed from the sealing body which consists of silicone resins.

  Other than that was carried out similarly to the said Example 1, and produced the liquid crystal display device 1 of the comparative example 1. FIG.

  Using the liquid crystal display devices of Example 1 and Comparative Example 1 made by the above method, the luminance variation of white light was visually compared. As shown in Table 1 below, Example 1 was more white light. It was confirmed that a good image was obtained with little variation in luminance.

  The effects of the present invention are clear from the above results. That is, the backlight device of the present invention is a backlight device having a light guide plate and a light source disposed at an end of the light guide plate, the light source having an element that emits blue light, and the light guide. Since the light plate is configured to contain phosphor fine particles that are excited by the blue light and convert the wavelength of the blue light, the light plate has a small amount of use of the element that emits blue light provided in the light source. In the portable electronic device, the problem of variation in the color temperature of white light emitted from the light exit surface of the light guide plate can be improved.

  It can be widely used in the electronics industry including flat displays.

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device 13R ... Red colored layer 13G ... Green colored layer 13B ... Blue colored layer 30 ... Color filter substrate 100 ... Display array substrate 150 ... Liquid crystal display panel 200 ... Backlight device 210 ... Light guide plate 210a ... Light incident surface 210b ... Light exit surface 220 ... Light source 240B ... Blue light emitting part 241 ... Light emitting element 242 ... Sealing body

Claims (10)

A backlight device having a light guide plate and a light source disposed at an end of the light guide plate,
The light source includes an element that emits blue light,
The light guide plate contains phosphor fine particles that are excited by the blue light and convert the wavelength of the blue light ,
The light guide plate has a light incident surface and a light exit surface,
An element emitting blue light is disposed on the light incident surface side of the light guide plate,
A plurality of light extraction openings are formed on the light exit surface side of the light guide plate, and the area of the light extraction opening gradually increases as the distance from the light incident surface side of the light guide plate increases. backlight device surface portion other than the light outlet of the light exit surface side, wherein Rukoto to having a reflective layer function.   The backlight device according to claim 1, wherein the phosphor fine particles are made of a yellow phosphor.   The backlight device according to claim 1, wherein the phosphor fine particles include a red phosphor and a green phosphor. The yellow phosphor includes a YAG phosphor ((Y, Gd) ₃ Al ₅ O ₁₂ : Ce ³⁺ ), a silicate phosphor ((Sr, Ba) ₂ SiO ₄ : Eu ²⁺ ), a nitride phosphor ( _{3. The} structure according to claim 2, comprising one selected from (Ca, Sr, Ba) AlSiN ₃ : Eu ²⁺ ) and an oxynitride phosphor (Ba ₃ Si ₆ O ₁₂ N ₂ : Eu ²⁺ ). Backlight device. The red phosphor is M ₂ O ₂ S: Eu ²⁺ (where M is one or more elements selected from La, Gd, and Y), 0.5 MgF ₂ .3.5MgO.GeO _2. : Mn ²⁺ , Y ₂ O ₃ : Eu ²⁺ , Y (P, V) O ₄ : Eu ²⁺ , YVO ₄ : One selected from Eu ²⁺
The green phosphor includes RMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ (where R is one or both elements selected from Sr and Ba), RMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ (wherein R is one or both elements selected from Sr and Ba), ZnS: Cu ²⁺ , SrAl ₂ O ₄ : Eu ²⁺ , SrAl ₂ O ₄ : Eu ²⁺ , Dy ^{2 +} , ZnO: Zn ²⁺ , Zn ₂ Ge ₂ O ₄ : Mn ²⁺ , Zn ₂ SiO ₄ : Mn ²⁺ , Q ₃ MgSi ₂ O ₈ : Eu ²⁺ , Mn ²⁺ (where Q is Sr, Ba , Any one element selected from Ca, or one or more elements selected from Ca).   The backlight device according to any one of claims 1 to 5, wherein the element emitting blue light is a blue LED, and the number of blue LEDs arranged at an end portion of the light guide plate is 4 to 50. .   The backlight device according to any one of claims 1 to 6, wherein the phosphor fine particles are uniformly dispersed inside the light guide plate.   The backlight device according to claim 1, wherein the backlight device is configured in an edge light system. The optical sheet on the light emitting side of the light guide plate is arranged, according to any one of claims 1 reflection film is disposed on the rear side is the opposite side of the light exit plane of the light guide plate according to claim 8 Backlight device. A liquid crystal display device comprising the backlight device according to any one of claims 1 to 9 and a liquid crystal display panel,
The liquid crystal display panel includes a color filter substrate and a display array substrate.

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