JP2009238406A - Back light unit and reflective sheet - Google Patents

Abstract

When a reflective sheet is attached to a linear light source device, even if the reflective sheet is slightly displaced in the direction of the light guide plate, the light distribution characteristics are not affected, thereby suppressing a decrease in yield. Provided is a backlight unit and a reflective sheet.
A backlight unit 1 includes a substrate 71, a linear light source device 7 including a plurality of light emitting elements 72 arranged on the substrate 71, and reflecting portions 73 arranged on both sides of the light emitting elements 72, respectively. Between the light guide plate 6 that emits light from the linear light source device 7 as illumination light, and between the linear light source device 7 and the light guide plate 6 that are arranged with the light emitting element 72 facing the side surface 61 of the light guide plate 6. And a reflection sheet 8 arranged so as to straddle. Then, the reflection sheet 8 is formed in a range in which a reflection surface 81 that reflects light from the linear light source device 7 to the side surface 61 of the light guide plate 6 is secured between the inclined surfaces 73 a and is bonded to the substrate 71. The surface 82 is formed on the remainder excluding the reflective surface 81.
[Selection] Figure 3

Description

  The present invention relates to a backlight unit and a reflection sheet in which a linear light source device is disposed on one side surface that is an incident surface of a light guide plate that emits illumination light from a main light emitting surface.

  In the backlight unit, a light emitting element, which is a point light source mounted on a substrate, is arranged on a case frame that surrounds the side surface of the light guide plate so as to irradiate one side of the light guide plate. Is incident and emitted from the main irradiation surface of the light guide plate, thereby functioning as a surface light emitting device that brightly illuminates a display panel such as an LCD.

  Such a backlight unit is described in Patent Document 1. Patent Document 1 describes a backlight assembly including a white light emitting unit that is a light emitting device, a light guide plate, an optical sheet, and a frame-shaped mold frame that is a case frame as a backlight unit. . The white light emitting unit includes a printed circuit board, a plurality of light emitting diodes mounted on the printed circuit board, and a lens housed in a housing groove of the light guide plate, and is disposed on one side of the upper part of the mold frame. In order to reflect the light diverging from the lens into the lens, reflection bands are arranged on the upper and lower surfaces (first surface, second surface) of the lens.

  In the backlight assembly described in Patent Document 1, a white light emitting unit in which a side view type light emitting diode is mounted on a printed circuit board formed of FPC is employed. However, side view type light emitting diodes tend to cause hot spots due to their narrow light distribution characteristics. Therefore, for example, a linear light source device described in Patent Document 2 can be employed as a light source used in the backlight unit.

  In the linear light source device described in Patent Document 2, a plurality of light emitting elements are arranged along the longitudinal direction of an elongated rectangular bar-shaped printed circuit board, and reflected so as to alternate with each light emitting element on both sides of each light emitting element. A plate (reflecting part) is arranged, and the opposing surfaces of both reflecting plates are inclined so that the opening area becomes larger toward the emitting direction of each light emitting element, and the concave part formed by the printed circuit board, the light emitting element, and the reflecting plate is formed. A resin sealing material (resin sealing portion) having a trapezoidal shape or a trapezoidal shape is formed by filling a light-transmitting resin sealing material. A wide light distribution characteristic can be obtained by arranging the linear light source device with the light emitting element facing one side surface of the light guide plate.

  However, when such a linear light source device is simply disposed on one side of the light guide plate, in addition to the light incident on the side surface of the light guide plate either directly or reflected on the reflector, Light traveling in the direction orthogonal to the longitudinal direction leaks from the resin sealing portion. Therefore, in order to reflect the light leaking from the resin sealing portion in the direction of the light guide plate, the reflection sheet is attached so as to straddle the linear light source device and the light guide plate. This reflection sheet will be described with reference to FIG.

As shown in FIG. 6, the linear light source device 101 is arranged on the side surface 100a of the light guide plate 100 with the mounting surface F of the substrate 101b on which the light emitting element 101a is mounted facing the side surface 100a. And the elongate reflective sheet 103 is affixed so that the light-guide plate 100 and the linear light source device 101 may be straddled. In this reflection sheet 103, the entire inner surface facing the light guide plate 100 and the linear light source device 101 is a metallic gloss surface, but a double-sided tape is provided on the linear light source device 101 side and the light guide plate 100 side along the longitudinal direction. The adhesion surface 103a is formed by being affixed. Accordingly, only the central portion along the longitudinal direction functions as the reflecting surface 103b. The width of the bonding surface 103a on the linear light source device 101 side is formed to the thickness of the substrate 101b in order to effectively reflect the light from the light emitting element 101a. In this way, the reflection sheet 103 provided with the reflection surface 103 b is attached to the light guide plate 100 together with the linear light source device 101 so as to cover the resin sealing portion 102 c.
JP 2006-108606 A JP 2004-235139 A

  However, in the conventional backlight unit shown in FIG. 6, if the reflective sheet 103 is pasted at a position shifted to the light guide plate 100 side, the bonding surface 103 a that should be bonded only to the substrate 101 b is formed as a resin. This leads to the sealing portion 102c. Then, since the light emitted from the light emitting element 101a cannot be efficiently reflected by the adhesive surface 103a, the backlight unit pasted at the position where the reflective sheet 103 is shifted and the backlight pasted without the reflective sheet 103 being shifted. The light distribution characteristics of the linear light source device change with the unit, resulting in variations.

  The size of the reflection sheet 103 needs to match the size of the linear light source device 101. Therefore, since the size of the linear light source device is increased in a large-sized backlight unit, the work of attaching the reflective sheet to the light guide plate and the linear light source device is easy, and thus “displacement” hardly occurs. However, for example, when used in a liquid crystal display panel of a mobile phone, the thickness of the substrate of the linear light source device is 0.5 mm. If it does so, even if the sticking position of a reflective sheet shifts | deviates a little, the adhesive surface of a reflective sheet will cover a resin sealing layer, will lead to deterioration of a light distribution characteristic, and a yield will deteriorate. Further, even in the case of a large-sized backlight unit, it is considered that the linear light source device is required to be thinned, the thickness of the substrate becomes thinner and the place where the reflection sheet is attached becomes narrower.

  Therefore, the present invention reduces the yield by preventing the light distribution characteristics from being affected even if the reflective sheet is slightly displaced in the direction of the light guide plate when the reflective sheet is attached to the linear light source device. An object of the present invention is to provide a backlight unit and a reflection sheet that can be suppressed.

  In the present invention, the reflecting sheet is formed of a long tape, and the reflecting surface that reflects the light from the light emitting element of the linear light source device to one side surface of the light guide plate is formed between the inclined surfaces of the reflecting portions of the linear light source device. An adhesive surface that is formed at a position between them and adheres to the linear light source device is formed at the position of the reflective portion.

  Since the present invention does not affect the light distribution characteristics even if it is displaced in the direction of the light guide plate when attaching the reflection sheet, it is possible to suppress a decrease in yield.

  1st invention of this application is a light emitting element with the elongate board | substrate, the light emitting element arrange | positioned along the longitudinal direction of a board | substrate, and the opposing surface which is each arrange | positioned on both sides of a light emitting element and pinches | interposes a light emitting element in between A linear light source device having a reflecting portion formed on an inclined surface whose interval gradually increases as it goes in the emission direction of light, and light from the linear light source device is incident from one side surface and is emitted from the main light emitting surface as illumination light The light guide plate that is emitted and a reflective sheet that is formed with a long tape and is disposed so as to straddle between the light source plate and the linear light source device that is arranged with the light emitting element facing one side of the light guide plate The reflective sheet is formed in a range in which a reflective surface that reflects light from the linear light source device to one side surface of the light guide plate is secured at least between the inclined surfaces, and an adhesive surface that adheres to the substrate is Characterized by being formed on the remainder excluding the reflective surface A.

  The reflection surface of the reflection sheet that reflects light from the light emitting element to one side surface of the light guide plate is formed in a range that secures at least between the inclined surfaces, and the adhesion surface that adheres to the linear light source device is the reflection surface It is formed in the remainder except. Therefore, the reflective sheet is fixed by adhering to the substrate by the adhesive surface, and the light from the light emitting element that emits light between the inclined surfaces can be reliably reflected to one side surface of the light guide plate by the reflective surface. And even if the reflection sheet is attached to the position shifted to the light guide plate side, since the adhesive surface is not formed between the inclined surfaces, the light from the light emitting element is reflected to the light guide plate by the reflection surface. Can do. Therefore, the light distribution characteristics are not affected.

  According to a second invention of the present application, in the first invention, the reflection sheet is formed such that the entire inner surface of the tape is formed on a metal glossy surface, and an adhesive surface is formed on the metal glossy surface so that the remainder of the metal glossy surface is reflected. It is characterized by being a surface.

  Since the entire inner surface of the tape is formed on a metallic glossy surface and an adhesive surface is formed on this metallic glossy surface, the rest becomes a reflective surface, so that a reflective sheet can be easily formed.

  According to a third aspect of the present invention, there is provided a long substrate, a plurality of light emitting elements arranged along the longitudinal direction of the substrate, and a light emitting element having opposing surfaces that are arranged on both sides of the light emitting element and sandwich the light emitting element therebetween. A light source plate having a linear light source device provided with a reflecting portion formed on an inclined surface that spreads in the direction of light emission, and light from the linear light source device incident from one side and exiting from the main light emitting surface as illumination light A reflective sheet of a backlight unit comprising: a linear light source device formed of a long tape and disposed with a light emitting element facing one side of the light guide plate; and a light guide plate The reflective surface that is arranged so as to straddle and reflects the light from the light emitting element to one side of the light guide plate is formed in a range that secures at least between the inclined surfaces, and the adhesive surface that adheres to the linear light source device reflects It is formed in the remainder excluding the surface It is intended.

  The reflection surface of the reflection sheet that reflects light from the light emitting element to one side surface of the light guide plate is formed in a range that secures at least between the inclined surfaces, and the adhesion surface that adheres to the linear light source device is the reflection surface It is formed in the remainder except. Therefore, the reflective sheet is fixed by adhering to the substrate with the adhesive surface, and the light from the light emitting element that emits light between the inclined surfaces can be reliably reflected to one side surface of the light guide plate by the reflective surface. Even if the reflection sheet is attached to the position shifted to the light guide plate side, no adhesive surface is formed between the inclined surfaces, so that the light from the light emitting element is reflected by the reflection surface to the light guide plate. be able to. Therefore, the light distribution characteristics are not affected.

  According to a fourth invention of the present application, in the third invention, the entire inner surface of the tape is formed on a metallic glossy surface, and an adhesive surface is formed on the metallic glossy surface, so that the remainder of the metallic glossy surface is a reflective surface. It is characterized by.

  By forming the entire inner surface of the tape on a metallic glossy surface and forming an adhesive surface on this metallic glossy surface, the remainder becomes a reflective surface, so that a reflective sheet can be easily formed.

(Embodiment)
A backlight unit according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of a backlight unit according to an embodiment of the present invention. FIG. 2 is a diagram for explaining a linear light source device used in the backlight unit shown in FIG.

  As shown in FIG. 1, the backlight unit 1 includes a metal case 2, a reflective film 3, a fixed sheet 4, a case frame 5, a light guide plate 6, a linear light source device 7, a reflective sheet 8, A light control film 9 and a light shielding sheet 10 are provided.

  The metal case 2 is a case base formed by a flat plate portion 21 that is a rectangular flat plate and a peripheral wall portion 22 that is erected from the periphery of the flat plate portion 21.

  The reflective film 3 is a rectangular film housed in the metal case 2. It has a function of reflecting light from the bottom surface of the light guide plate 6 toward the light guide plate 6 side. As the reflective film 3, an ESR (Enhanced Specular Reflector) having a high reflectance in the visible light range can be used due to a multilayer film structure using a polyester-based resin. Any other material may be used. The reflective film 3 not only reflects the light from the bottom surface of the light guide plate 6 but also reflects the light from the linear light source device 7, so that the reflective projection 32 protrudes from the rectangular film body 31. .

  The fixing sheet 4 is a tape for fixing the linear light source device 7 to the metal case 2. The fixed sheet 4 is formed with a trapezoidal portion 41 that adheres to the reflective film 3 and a fixed convex portion 42 that protrudes from the trapezoidal portion 41 and adheres to the linear light source device 7.

  The case frame 5 is disposed between the light guide plate 6 placed on the flat plate portion 21 and the peripheral wall portion 22, and has a substantially U-shaped frame portion 51 that holds the side surface of the light guide plate, and the linear light source device 7. A cutout portion 52 in which a part of the frame portion 51 for storage is cut out is formed. Therefore, in the space for placing the linear light source device 7 secured by the notch 52, a part of the flat plate portion 21 becomes a floor portion.

  The light guide plate 6 is formed in a substantially rectangular shape, and the light from the linear light source device 7 is incident from the side surface and is emitted from the main light emitting surface as illumination light. It is a transparent or translucent plate-like body formed to a thickness of about 0.6 mm.

  As shown in FIG. 2, the linear light source device 7 is a light emitting device including a substrate 71, a light emitting element 72, a reflecting portion 73, a resin sealing portion 74, and a printed wiring board 75.

  The substrate 71 is a printed wiring board in which a wiring pattern is formed on a rectangular bar-shaped insulating substrate. The insulating substrate can be formed of glass epoxy resin, BT resin (bismaleimide triazine resin thermosetting resin), or the like.

  The light emitting element 72 is formed by stacking a semiconductor layer including a light emitting layer on a conductive substrate formed of a semiconductor or an insulating substrate formed of sapphire. It is mounted on the mounting surface F.

  The reflection portion 73 is formed by two members located on both sides of the light emitting element 72. Each surface (reflective surface) facing the light emitting element 72 in the reflection portion 73 reflects light from the light emitting element 72 in the direction of the light guide plate 6 (see FIG. 1). It becomes the inclined surface 73a from which a space | interval becomes wide gradually as it goes.

  The resin sealing part 74 seals the light emitting element 72 located between each reflection part 73 with the epoxy resin. In the linear light source device 7, a light source unit is configured by the light emitting element 72 and the resin sealing unit 74. Four light source portions are provided on the substrate 71. The resin sealing portion 74 can contain a phosphor that emits light that is excited by light from the light emitting element 72 and converted in wavelength as necessary. For example, if the light-emitting element 72 emits blue light, the phosphor emits light in yellow, which is a complementary color of blue, so that the light source unit emits white light by mixing blue and yellow. Can do.

  The printed wiring board 75 includes a connection portion 751 formed along the substrate 71 and a wiring portion 752 connected to a connector that supplies power, and is formed of a flexible flexible substrate. The printed wiring board 75 is fixed to the substrate 71 by terminals connected to the electrodes provided on the substrate 71 being electrically connected to the electrodes by solder B.

  The reflection sheet 8 is affixed across the linear light source device 7 and the light guide plate 6 along the substrate 71 of the linear light source device 7 to reflect light from the light emitting element 72 toward the light guide plate 6. It is.

  Here, the reflective surface and adhesive surface provided in the reflective sheet 8 will be described in detail with reference to FIG. FIG. 3 is a diagram illustrating a state where the reflection sheet 8 is attached to the light guide plate 6 and the linear light source device 7.

  As shown in FIG. 3, the reflection sheet 8 is a long tape, and the entire inner surface facing the linear light source device 7 and the light guide plate 6 is a metallic gloss surface. A range slightly wider than the reflective portion 73 sandwiching the light emitting element 72 is used as a reflective surface 81, and a range between the reflective portion 73 and the adjacent reflective portion 73 is used as an adhesive surface 82. This is because the light from the light emitting element 72 is directly directed toward the light guide plate 6 and reflected from the inclined surface 73a of the reflecting portion 73 to become light directed toward the light guide plate 6 in addition to the length of the substrate 71. Light emitted in a direction orthogonal to the direction becomes light leaking from the resin sealing portion 74. Therefore, in order to direct this leaking light in the direction of the light guide plate 6, it is only necessary that the reflecting surface 81 is located at least in a range between the inclined surfaces 73 a. Therefore, a range in which the space between the inclined surfaces 73 a is secured may be the reflective surface 81, and the remainder excluding the reflective surface 81 may be the adhesive surface 82. In the present embodiment, even if the reflective sheet 8 is slightly displaced along the substrate 71 of the linear light source device 7, the adhesive surface is not adjacent to the reflective portion 73 so as not to cover the resin sealing portion 74. As a range in between, the rest of the surface excluding the adhesive surface 82 is used as the reflective surface 81, so that a wide range of the reflective surface 81 is secured.

  Returning to FIG. 1, the light control film 9 includes a diffusion film 91, a first prism film 92, and a second prism film 93. The diffusion film 91 is formed of a polyester (PS) resin or a polycarbonate (PC) resin and has a rough surface like ground glass. The first and second prism films 92 and 93 have prism surfaces in which triangular strips made of acrylic resin are formed on the surface of a polyester resin. This prism surface is formed in a sawtooth shape in a sectional view. The first and second prism films 92 and 93 are arranged so that the strip directions overlap in a direction substantially orthogonal to each other.

  The light shielding sheet 10 is an opaque sheet that is attached to the second prism film 93 so as to correspond to the linear light source device 7.

  The usage state of the backlight unit 1 according to the embodiment of the present invention configured as described above will be described with reference to FIGS. 1 to 3 and FIGS. 4 and 5. FIG. FIG. 4 is a diagram showing a state where the light guide plate 6 and the linear light source device 7 are fixed on the reflection film 3 by the fixing sheet 4.

  As shown in FIGS. 4 and 5, most of the light from the light emitting element 72 travels toward the side surface 61 of the light guide plate 6, but part of the light travels in the direction of the inclined surface 73 a of the reflecting portion 73. . The light traveling toward the inclined surface 73 a is reflected by the inclined surface 73 a and travels in the direction of the light guide plate 6. Further, the light from the light emitting element 72 tries to leak out through the resin sealing portion 74 in a direction orthogonal to the longitudinal direction of the substrate 71 without going to the side surface 61 other than toward the inclined surface 73a. There is light. One of the light leaking out is light directed toward the reflective film 3, and the other is light directed toward the reflective sheet 8.

  The light traveling toward the reflective film 3 is reflected by the reflective film 3 and reaches the side surface 61 of the light guide plate 6. The fixed sheet 4 protrudes from the trapezoidal portion 41 in a range between the reflective portion 73 of the linear light source device 7 and the adjacent reflective portion 73, so that the fixed sheet 4 is positioned between the fixed convex portions 42. The reflective convex portion 32 of the reflective film 3 is in a state exposed to the linear light source device 7. Therefore, the light traveling in the direction of the reflective film 3 can be efficiently reflected by the reflective film 3 and traveled to the side surface 61 of the light guide plate 6 without being blocked by the fixing sheet 4.

  As shown in FIGS. 3 and 5, the light traveling toward the reflection sheet 8 is reflected by the reflection surface 81 of the reflection sheet 8 attached on the linear light source device 7, to the side surface 61 of the light guide plate 6. To reach.

  Since the reflection sheet 8 has a bonding surface 82 between the reflection portion 73 and the adjacent reflection portion 73 in order to secure at least a range between the inclined surfaces 73a as the reflection surface 81, the reflection sheet 8 is reliably reflected. Light traveling toward the sheet 8 can be reflected to the side surface 61 of the light guide plate 6. In addition, even when the reflective sheet 8 is displaced in the direction of the light guide plate 6, the reflective surface 81 is provided in the entire width direction, and no adhesive surface is formed between the inclined surfaces 73a. It does not affect the light distribution characteristics.

  Since the adhesive surface 82 is a range between the reflective portion 73 and the adjacent reflective portion 73 and is provided over the entire width direction, both the substrate 71 and the light guide plate 6 of the linear light source device 7 are provided. It can be bonded across.

  As described above, the backlight unit 1 according to the present embodiment does not affect the light distribution characteristics even if it is displaced in the direction of the light guide plate 6 when the reflection sheet 8 is attached. The chromaticity at the contained resin sealing portion 74 can be stabilized. Accordingly, it is possible to suppress a decrease in the yield of the backlight unit 1.

  In the present invention, when the reflective sheet is attached to the linear light source device, even if the reflective sheet is slightly deviated in the direction of the light guide plate, the light distribution characteristics are not affected, thereby suppressing a decrease in yield. Therefore, the linear light source device is suitable for a backlight unit and a reflection sheet that are arranged on one side as an incident surface of a light guide plate that emits from a main light emitting surface as illumination light.

1 is an exploded perspective view of a backlight unit according to an embodiment of the present invention. The figure for demonstrating the linear light source device used for the backlight unit shown in FIG. The figure which shows the state by which the reflective sheet is affixed on the light-guide plate and the linear light source device The figure which shows the state by which the light-guide plate and the linear light source device are being fixed on the reflective film with the fixing sheet. Partial sectional view of the backlight unit shown in FIG. The figure which shows the state by which the conventional reflection sheet is affixed on the light-guide plate and the linear light source device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Backlight unit 2 Metal case 3 Reflective film 4 Fixed sheet 5 Case frame 6 Light guide plate 7 Linear light source device 8 Reflective sheet 9 Light control film 10 Light shielding sheet 21 Flat plate part 22 Perimeter wall part 31 Film main body 32 Reflective convex part 41 Trapezoid part 42 Fixed convex part 51 Frame part 52 Notch part 61 Side surface 71 Board | substrate 72 Light emitting element 73 Reflection part 73a Inclined surface 74 Resin sealing part 75 Printed wiring board 81 Reflection surface 82 Adhesion surface 91 Diffusion film 92 1st prism film 93 2nd prism Film 751 Connection part 752 Wiring part

Claims (4)

A long substrate, a plurality of light-emitting elements arranged along the longitudinal direction of the substrate, and opposite surfaces arranged on both sides of the light-emitting element, with the light-emitting elements sandwiched therebetween in the emission direction of the light-emitting elements A linear light source device including a reflecting portion formed on an inclined surface with a space gradually widening as it goes,
A light guide plate that enters light from the linear light source device from one side surface and emits light from the main light emitting surface as illumination light;
A linear light source device that is formed of a long tape and is arranged with the light emitting element facing one side surface of the light guide plate, and a reflective sheet that is arranged so as to straddle between the light guide plate ,
The reflective sheet is
A reflection surface that reflects light from the linear light source device to one side surface of the light guide plate is formed in a range that secures at least a space between the inclined surfaces,
The backlight unit is characterized in that an adhesive surface that adheres to the substrate is formed on the remainder excluding the reflective surface. 2. The reflective sheet according to claim 1, wherein an inner side surface of the tape is formed on a metallic glossy surface, and the adhesive surface is formed on the metallic glossy surface, and the remainder of the metallic glossy surface is the reflective surface. Backlight unit. A long substrate, a plurality of light-emitting elements arranged along the longitudinal direction of the substrate, and opposite surfaces arranged on both sides of the light-emitting element, with the light-emitting elements sandwiched therebetween in the emission direction of the light-emitting elements A linear light source device including a reflecting portion formed on an inclined surface that spreads toward the head, and a light guide plate that makes light from the linear light source device incident from one side surface and exits from the main light emitting surface as illumination light. A reflective sheet of a backlight unit,
It is formed of a long tape and is arranged so as to straddle between the light guide plate and the linear light source device arranged with the light emitting element facing one side of the light guide plate. A reflective surface that reflects light to one side of the light guide plate is formed in a range that secures at least the space between the inclined surfaces, and an adhesive surface that adheres to the linear light source device is formed on the remainder excluding the reflective surface Reflective sheet characterized by being made. The reflection sheet according to claim 3, wherein the entire inner surface of the tape is formed on a metallic glossy surface, and the adhesive surface is formed on the metallic glossy surface, so that the remainder of the metallic glossy surface is the reflective surface.

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