JP2007095674A - Plane light source device and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin plane light source device with reduced brightness irregularity and color irregularity and a display device including the plane light source device. <P>SOLUTION: Disclosed is the plane light source device including a substrate on which a solid-state light-emitting element is placed, a light guide member disposed above the substrate in a face-to-face manner and a reflection member disposed on a lower surface of the light guide member, wherein a recessed part is provided on at least one of a top surface and a back surface of the light guide member; and the display device including the plane light source device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a surface light source device and a display device, and more particularly to a surface light source device that radiates emitted light from a light source used in a liquid crystal display device or the like from the surface of a light guide plate to the outside, and a display device including the surface light source device. .

  In recent years, display devices using a surface light source device (backlight) for irradiating light from the back surface or side surface of a panel, such as a liquid crystal display device, have been widely used. Among them, in a liquid crystal television and a liquid crystal monitor, conventionally, a fluorescent tube of a hot cathode type or a cold cathode type has been adopted as a backlight device. As a light emitting device such as a backlight using the fluorescent tube, there is a so-called direct type in which the fluorescent tube is arranged on a plane directly under (backside) the liquid crystal panel. In addition, a fluorescent tube is installed only on two sides or one side of a transparent resin light guide plate, and the light incident on the light guide plate is reflected by a reflecting portion provided on the back surface of the light guide plate to irradiate the liquid crystal panel surface. There is an edge light type.

  This direct type is excellent in that high luminance can be secured, but is disadvantageous for making the backlight thinner. In addition, the edge light type is superior in that it can be made thinner than the direct type, but is disadvantageous in terms of uniform luminance for large screens. Therefore, as an alternative to a backlight device using such a fluorescent tube, a backlight device using a light emitting diode (LED), which is one of solid-state light emitting elements, as a light source has recently been studied. .

  FIG. 11 is a schematic cross-sectional view showing the structure of a direct type surface light source device 102 using a light emitting diode arranged immediately below a conventional liquid crystal display panel 101 disclosed in Non-Patent Document 1. In the surface light source device 102, an LED substrate (mounting substrate) as a substrate (not shown) in which a plurality of light emitting diodes 103 are planarly arranged as a light source is provided on the bottom surface of the housing 104. The bottom and side surfaces of the housing are covered with a reflection sheet 105. A diffusion plate 106 and a prism sheet 107 are disposed at a distance of usually 2 to 5 cm from the light emitting diode 103.

  When the light emitting diode 103 is caused to emit light, the emitted light is reflected directly or by the reflection sheet 105 toward the diffusion plate 106, is diffusely reflected in the diffusion plate 106, and then passes through the prism sheet 107 in the vertical direction. The light beam is tilted and enters the liquid crystal panel 101. Light emitted from different light emitting diodes 103 is mixed in a space between the diffuser plate 106 and further diffusely reflected in the diffuser plate 106 to promote mixing, thereby making the luminance uniform. In general, the luminance corresponding to the portion immediately above the light emitting diode 103 is increased. Therefore, in the diffusion plate 106, the luminance can be made more uniform by increasing the diffusion degree of the portion.

However, in the conventional surface light source device using a light emitting diode, a diffusion plate is provided and the distance between the light emitting diode and the diffusion plate is increased in order to make the luminance uniform as described above. There is a problem that the luminance directly above the diode is increased. In particular, when color mixing is performed using light emitting diodes of a plurality of colors (RGB) instead of single color light emitting diodes, there is a problem that color mixing is not sufficient and color unevenness is visible. In order to reduce luminance unevenness and color unevenness, as described above, in the diffusion plate, the diffusion degree corresponding to the portion directly above the light emitting diode is increased, or a so-called lighting curtain is provided directly above the light emitting diode. For example, the brightness of the upper part is lowered. However, these means cause a decrease in light utilization efficiency. Further, if the distance between the light emitting diode and the diffusion plate is increased, the luminance and chromaticity unevenness can be reduced, but this increases the thickness of the backlight, which is not preferable for a flat panel display.
TECHNO-FRONTIER SYMPOSIUM 2005 Thermal Design and Countermeasure Technology Symposium, published date. April 20, 2005 (Japan Management Association), Session G3 Latest design example I of heat dissipation mounting (p.G3-3-1 to G3-3-4).

  An object of the present invention is to provide a surface light source device in which luminance unevenness due to high luminance at a position immediately above the light source is reduced without increasing the thickness of the surface light source device.

Another object of the present invention is to provide a surface light source device in which not only luminance unevenness but also color unevenness is reduced when using light emitting diodes of a plurality of colors (RGB).
Furthermore, an object of the present invention is to provide a display device having such a surface light source device.

The present inventors have found a method for uniformizing luminance and chromaticity in a surface light source device (backlight) using a solid light emitting element as a light source, and have reached the present invention.
That is, the present invention includes, for example, the following aspects (1) to (10).

  (1) A surface of the light guide member having a substrate on which a solid light emitting element is placed, a light guide member disposed above the substrate, and a reflective member disposed on a lower surface of the light guide member. And a surface light source device, wherein a concave portion is provided on at least one surface of the back surface.

(2) The surface light source device according to (1), wherein the concave portion is provided at a position immediately above the solid state light emitting device.
(3) The surface light source device according to (1) or (2), wherein the shape of the recess is a cone, a pyramid, a cylinder, a prism, or a hemisphere.

(4) The surface light source device according to any one of (1) to (3), wherein the concave portion is provided on a lower surface of the light guide member.
(5) The surface light source device according to any one of (1) to (4), wherein a light scattering dot is provided on a lower surface of the light guide member.

(6) The surface light source device according to any one of (1) to (5), wherein the solid light-emitting element includes a red solid light-emitting element, a green solid light-emitting element, and a blue solid light-emitting element.
(7) On the surface of the light guide member, the distance from the position immediately above each solid light emitting element to the nearest light scattering dot is more than the distance from the solid light emitting element to the nearest solid light emitting element. The surface light source device according to (5) or (6), which is large.

  (8) A concave portion is provided on the upper surface of the substrate, and the solid-state light emitting element is installed in the concave portion so that the upper end thereof is located below the upper surface of the light emitting member. The surface light source device according to any one of 1) to (7).

(9) A display device comprising the surface light source device according to any one of (1) to (8).
(10) The display device according to (9), wherein the display unit is a liquid crystal panel.

  The surface light source device of the present invention is thin and has good uniformity in luminance and chromaticity. Particularly, when the surface light source device of the present invention is used as a backlight of a liquid crystal display, a high-quality image can be obtained. .

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiments.
In the description of the embodiments of the present invention, for convenience, the direction from the solid light emitting element to the light guide member is referred to as “up”.

In a so-called direct type backlight, it is effective to use a light guide member in order to sufficiently achieve uniform luminance and chromaticity and prevent the surface light source device from becoming thick. In the direct type backlight, since the solid light emitting element is installed upward, it is desirable that the light is diffused and uniformly propagated in the light guide member.
FIG. 1 is a diagram showing an overall configuration of a liquid crystal display device to which the present embodiment is applied. A liquid crystal display device to which the present embodiment is applied includes a direct-type backlight device (backlight) 10, a backlight frame (housing) 11 that houses a light emitting portion, and light emission that is a solid light emitting element as a light source. An LED substrate (mounting substrate) 12 is provided as a substrate on which a plurality of diodes (LEDs) 13 are arranged. The backlight device 10 includes a light guide member (plate or film) 14 that is a feature of the present invention and is housed in a backlight frame (housing) 11 on an LED substrate (mounting substrate) 12. As a laminate of optical compensation sheets on the light guide member 14, a diffusion member (plate or diffusion film) 15 is a member (plate or film) that scatters and diffuses light so that the entire surface has uniform brightness. And prism sheets 16 and 17 which are diffraction grating films having a forward focusing effect. The liquid crystal display device includes, as a liquid crystal display module 30, a liquid crystal panel 31 in which liquid crystal is sandwiched between two glass substrates, and laminated on each glass substrate of the liquid crystal panel 31 to cause vibration of light waves in a certain direction. Polarizing plates (polarizing filters) 32 and 33 for limiting to the above. Further, peripheral members such as a driving LSI (not shown) are arranged in the liquid crystal display device.
The liquid crystal panel 31 includes various components not shown. For example, two glass substrates are provided with a display electrode (not shown), an active element such as a thin film transistor (TFT), a liquid crystal, a spacer, a sealing material, an alignment film, a common electrode, a protective film, a color filter, and the like. .
FIG. 2 is a partial schematic cross-sectional view of a light guide member (plate, film) 14 and an LED substrate (mounting substrate) 12 which are features of the surface light source device according to an embodiment of the present invention. LED board (mounting substrate) 12 mounted, a light guide member (plate, film) 14, and a reflective member (plate, film (coating film)) 18 disposed on the lower surface of the light guide member 14, A recess 14 a is provided on the lower surface of the light guide member 14. The reflective member (plate, film (coating film)) 18 is a white film, a metal thin film, or white painted on at least one of the lower surface of the light guide member (plate, film) 14 or the surface of the LED substrate (mounting substrate) 12. Examples thereof include a coated film and a reflector member (metal, white resin, etc.).

  With this configuration, at least a part of the light emitted upward from the light source is scattered by the concave portion and reflected by the upper surface and / or the lower surface of the light guide member, and then guided. Since the light is emitted from the upper surface of the light member, the luminance is increased above the light source to prevent uneven brightness, and the luminance distribution on the light emitting surface of the light guide member can be made uniform.

  Here, by providing the concave portion at a position directly above the light emitting diode of the light guide member having the highest luminance, it is possible to efficiently reduce luminance unevenness above the light emitting diode.

  The “position immediately above the light emitting diode” means a position where the distance from the light emitting diode of interest is the shortest on the upper surface or the lower surface of the light guide member. Therefore, in the case of “a concave portion is provided on the surface of the light guide member and immediately above the light emitting diode”, as shown in FIG. The center of the cross section coincides. However, it does not have to be exactly the same, and there may be some errors.

  In FIG. 2, the recess 14a is provided only on the lower surface of the light guide member 14, but the position of the recess 14a may be both on the upper surface and the lower surface of the light guide member 14 as shown in FIG. 5, only the upper surface of the light guide member 14 may be used.

In the surface light source device of the present invention, the recess is preferably a cone, a pyramid, a cylinder, a prism, or a hemisphere.
As shown in FIG. 2, when the light emitting diode 13 has a lens portion, and this lens portion protrudes from the LED substrate 12 on which the light emitting diode is disposed, the concave portion 14a on the lower surface of the light guide member 14 is formed. The shape is preferably a cylinder, a rectangular parallelepiped, a pyramid, or a hemisphere. Particularly preferred is a pyramid or hemispherical shape. In the case of a pyramid shape, the apex angle is preferably 120 degrees or less, particularly preferably 90 degrees or less and 45 degrees or more. Here, the apex angle means the apex angle of a triangle of a cross section obtained by cutting the pyramid on a plane including a perpendicular line from the apex of the pyramid to the bottom surface of the pyramid and at least one side forming the side surface of the pyramid.

  As shown in FIGS. 3 to 6, when the plurality of light emitting diodes are LED light sources installed on the same substrate so as not to have a protrusion, the recess formed on the lower surface of the light guide member is a cylinder or a rectangular parallelepiped. Or a pyramid, a cone, or a hemisphere is preferable. Particularly preferred is a pyramid or conical shape, and the apex angle is preferably 120 degrees or less, particularly preferably 90 degrees or less and 45 degrees or more. Thus, the concave portion 12a is provided on the upper surface of the LED substrate 12, and the light emitting diode 13 is installed in the concave portion 12a so that the upper end of the light emitting diode is located below the upper surface of the LED substrate 12, that is, light emission. More preferably, the diode is installed so as not to protrude upward from the upper surface of the LED substrate 12. By increasing the distance between the light emitting diode 13 and the recess 14a, it is possible to irradiate light over a wide range of the recess 14a, and thereby, the function of the recess to diffuse light can be made more effective. The recess 12a is preferably filled with a transparent resin up to the upper surface of the LED substrate 12 after the light emitting diode 13 is installed.

  Further, by forming a cylindrical, rectangular parallelepiped, pyramid, conical, or hemispherical concave portion on the upper surface of the light guide member 14, the light emitted from the light source can be bent in the lateral direction, and the luminance directly above the light emitting diode can be reduced. It can be reduced without causing loss. The shape of the recess is particularly preferably a pyramid or a cone, and the apex angle is preferably 120 degrees or less, particularly preferably 90 degrees or less and 45 degrees or more.

  The cross-sectional area at the position where the cross-sectional area of the light emitting diode 13 is maximized, as viewed from the light guide member 14 side, is the cross-sectional area at the position where the cross-sectional area of the concave portion 14a provided in the light guide member is maximum. It may be small or large, and both may be the same. 2 to 5 correspond to the case where the cross-sectional area of the light-emitting diode 13 is smaller than the cross-sectional area of the recess 14a, and FIG. 6 illustrates the case where the cross-sectional area of the light-emitting diode 3 is larger than the cross-sectional area of the recess 14a. Corresponding to

By forming a printing pattern instead of forming a recess on the upper surface of the light guide member, the luminance directly above the light emitting diode can be reduced without causing light loss. The print pattern is preferably a circular pattern centered on the position directly above the light emitting diode, and the light guide member has a minimum transmittance at the center of the pattern and increases toward the periphery. Particularly preferred is a pattern in which the transmittance b (%) is approximately expressed as a quadratic function of a (mm) when the distance from the center of the printed pattern is a (mm). An example of the pattern is shown in FIG. The hatched portion is a printing unit that controls to lower the light transmittance, and the print pattern region is smaller and the light transmittance is larger as a is larger. Note that the plurality of concentric annular lines shown in FIG. 7 are shown in the description of the drawings, and need not be provided in the actual print pattern. In FIG. 7, a shape obtained by cutting out a part of the ring is formed as a unit pattern. However, the shape is not limited to this shape, and various shapes such as a circle and a rectangle can be used.

  In order to effectively extract light from the light guide member, it is preferable to form light scattering dots on the lower surface of the light guide member. The light scattering dots can be formed by dot printing of scattering ink or by integrally molding with a light guide member.

  In particular, when a red light emitting diode, a green light emitting diode, and a blue light emitting diode are used as the light emitting diodes and color mixing is performed, it is preferable that the light scattering dots are formed at a location away from each light emitting diode. More specifically, on the surface of the light guide member where the light scattering dots are formed, the distance from the position immediately above each light emitting diode to the closest light scattering dot is the distance from the light emitting diode. It is preferable to form the light scattering dots at a position that is larger than the distance to the adjacent light emitting diode. If the light scattering dots are formed at a position closer than this, the mixed colors of the three primary colors (RGB) are not sufficient, and color unevenness tends to occur in the surface light source.

  It is preferable to provide a diffusing member (plate or film) above the light guide member as in the liquid crystal display panel shown in FIG. In the embodiment of the present invention, only the light guide member is interposed between the light emitting diode 103 and the diffusion plate 106 in FIG. 11, and the thickness of the backlight is not increased.

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these embodiment.

[Example 1]
A 1W class 1mm square LED chip is placed on an aluminum base printed board 22 that is 110mm wide x 40mm long. As shown schematically in Fig. 8, the centers of the LED chips are green, red, blue, green, green, at intervals of 13mm. LED light sources mounted in a linear array in the order of red, blue and green were prepared.

A white reflective film (Lumirror (registered trademark) 60L) manufactured by Toray was bonded to the inner surface of an aluminum casing 21 having a bottom width of 280 mm × length of 234 mm and a depth of 30 mm.
Next, six LED light sources on which the LED chips were mounted were arranged and fixed on the bottom surface of the aluminum casing 21 in three rows and two columns as shown in FIG.

  10 is a schematic cross-sectional view taken along the line AA of the LED light source shown in FIG. The aluminum base printed circuit board 22 is configured by laminating a circuit board 21 having a circuit pattern (a circuit pattern is formed on a glass epoxy board) formed on an aluminum heat dissipating board 20 via an insulating layer. The LED chip 23 is bonded to the heat-dissipating substrate 20 with heat-dissipating grease at the opening 26 provided in the insulating layer, and the electrodes of the LED chip 23 and the terminals provided on the circuit board 21 are connected by bonding wires. Yes.

Each LED chip 23 is surrounded by an aluminum reflector 28 having a thickness higher than the highest part of the bonding wire and having an opening, and the reflector is fixed to the circuit board with an adhesive. . The opening of the reflector 28 has an inclined surface whose opening diameter is larger on the upper surface than the lower surface joined to the circuit board, and has a function of efficiently guiding light emitted from the LED by reflecting the light from the inclined surface of the reflector. is doing. The LED chip 23 is sealed by embedding a silicone resin or the like as the sealing resin 27 in the reflector opening, and the surface thereof is substantially flush with the reflector surface.

  The light guide plate 24 was placed on the LED light source arranged as shown in FIG. The light guide plate is a transparent plate made of polymethacrylate having a width of 270 mm, a length of 230 mm, and a thickness of 3 mm, and a cone having an apex angle of 90 degrees and a depth of 2.5 mm at a position directly below the center of each LED chip. The polymethacrylate transparent plate is laminated and fixed to the upper surface of the reflector with an adhesive so that a conical recess is provided and the bottom surface of the cone faces the LED chip.

Subsequently, a polycarbonate diffuser plate (PC9391-50HL) manufactured by Teijin Chemicals Ltd. was fixed at a position 30 mm above the inner bottom surface of the aluminum casing to manufacture a surface light source device.
Next, the red color is set so that the chromaticity coordinates at a position about 1 m away from the diffusion plate surface at the center of the diffusion plate (intersection of diagonal lines of the diffusion plate) are (x = 0.300, y = 0.300). Currents of 200 mA, 190 mA, and 128 mA were passed through the LED, green LED, and blue LED, respectively. The chromaticity coordinates and luminance were measured using a spectral radiance meter (spectral type) CS-1000S manufactured by Konica Minolta Holdings, Inc.

The luminance measured at a position about 1 m away from the diffusion plate surface at the center of the diffusion plate (intersection of diagonal lines of the diffusion plate) at this time was 2536 cd / m ² . About uneven color, about 1m from the diffuser surface
The chromaticity coordinates of the red, green, and blue parts were measured at the distant positions, and the difference from the center of the diffuser was compared and evaluated. The chromaticity coordinate of the most red part was (x = 0.320, y = 0.290), and the difference from the center was (Δx = 0.02, Δy = 0.01). Similarly, the green part is (x = 0.310, y = 0.320), (Δx = 0.01, Δy = 0.02), and the blue part is (x = 0.290, y = 0). .290), (Δx = 0.01, Δy = 0.01).

[Example 2]
A surface light source device was manufactured in the same manner as in Example 1 except that the apex angle of the conical concave portion of the polymethacrylate transparent plate used in Example 1 was set to 60 degrees. When the same evaluation as in Example 1 was performed, the luminance at a position about 1 m away from the diffusion plate surface at the center of the diffusion plate (intersection of the diagonal lines of the diffusion plate) was 2486 cd / m ^2. The chromaticity coordinate of the most red part at a position 1 m away was (x = 0.315, y = 0.290), and the difference from the center was (Δx = 0.015, Δy = 0.01). Similarly, the green part is (x = 0.310, y = 0.315), (Δx = 0.01, Δy = 0.015), and the blue part is (x = 0.285, y = 0). .285), (Δx = 0.015, Δy = 0.015).

[Example 3]
The depth of the conical concave portion of the transparent plate made of polymethacrylate used in Example 1 is 1.4 mm, and the apex angle is 90 degrees on the upper surface of the transparent plate and directly above all the concave portions. A surface light source device was manufactured in the same manner as in Example 1 except that a conical recess having a depth of 1.4 mm was provided. When the same evaluation as in Example 1 was performed, the luminance at a position about 1 m away from the diffusion plate surface at the center of the diffusion plate (intersection of the diagonal lines of the diffusion plate) was 2425 cd / m ² , and about 1 m away from the surface. The chromaticity coordinate of the most red portion at the position was (x = 0.308, y = 0.290), and the difference from the center was (Δx = 0.008, Δy = 0.01). Similarly, the green part is (x = 0.310, y = 0.308), (Δx = 0.01, Δy = 0.008), and the blue part is (x = 0.292, y = 0). .290), (Δx = 0.008, Δy = 0.01).

[Example 4]
Except that the conical concave portion of the polymethacrylate transparent plate used in Example 1 was changed to a square-shaped concave portion having a bottom surface of 2 mm × 2 mm and a depth of 2.5 mm, the same as in Example 1, A surface light source device was manufactured. When the same evaluation as in Example 1 was performed, the luminance at a position about 1 m away from the diffusion plate surface at the center of the diffusion plate (intersection of the diagonal lines of the diffusion plate) was 2588 cd / m ² and about 1 m away from the surface. The chromaticity coordinate of the most red portion at the position was (x = 0.310, y = 0.290), and the difference from the center was (Δx = 0.01, Δy = 0.01). Similarly, the green part is (x = 0.310, y = 0.315), (Δx = 0.01, Δy = 0.015), and the blue part is (x = 0.285, y = 0). .290), (Δx = 0.015, Δy = 0.01).

[Example 5]
Example 1 except that a pattern for controlling light transmittance was printed on the upper surface of the polymethacrylate transparent plate used in Example 1 so that the outer shape had a diameter of 16 mm at a position directly above the recess. Similarly, a surface light source device was manufactured. This pattern was formed so that the transmittance b (%) of the light guide plate at a position a (mm) from the center of the printed pattern satisfies the relationship of approximately b = 5 / 6a ² . When the same evaluation as in Example 1 was performed, the luminance at a position about 1 m away from the diffusion plate surface at the center of the diffusion plate (intersection of the diagonal lines of the diffusion plate) was 2486 cd / m ² , and about 1 m away from the surface. The chromaticity coordinate of the most red portion at the position was (x = 0.315, y = 0.290), and the difference from the center was (Δx = 0.015, Δy = 0.01). Similarly, the green part is (x = 0.310, y = 0.315), (Δx = 0.01, Δy = 0.015), and the blue part is (x = 0.285, y = 0). .285), (Δx = 0.015, Δy = 0.015).

[Comparative Example 1]
A surface light source device was manufactured in the same manner as in Example 1 except that a transparent plate made of polymethyl methacrylate was not used. When the same evaluation as in Example 1 was performed, the luminance at a position about 1 m away from the diffusion plate surface at the center of the diffusion plate (intersection of diagonal lines of the diffusion plate) was 2965 cd / m ² .
The chromaticity coordinate of the red part at a position about 1 m away from the surface is (x = 0.335, y = 0.28), and the difference from the center is (Δx = 0.035, Δy = 0.02). there were. Similarly, the green part is (x = 0.330, y = 0.350), (Δx = 0.03, Δy = 0.05), and the blue part is (x = 0.260, y = 0). .275), (Δx = 0.04, Δy = 0.025).

[Comparative Example 2]
A surface light source device was manufactured in the same manner as in Example 1 except that a smooth polymethylmethacrylate transparent plate having no recess was used. When the same evaluation as in Example 1 was performed, the luminance at a position about 1 m away from the diffusion plate surface at the center of the diffusion plate (intersection of the diagonal lines of the diffusion plate) was 2965 cd / m ² , and about 1 m away from the surface. The chromaticity coordinate of the redmost part at the position is (x = 0.350
, Y = 0.280), and the difference from the center was (Δx = 0.05, Δy = 0.02). Similarly, the green part is (x = 0.350, y = 0.350), (Δx = 0.05, Δy = 0.05), and the blue part is (x = 0.260, y = 0). .265), (Δx = 0.04, Δy = 0.35).

The above embodiment is an example, and the following various modifications are possible. Although a bare chip is used as the light emitting diode (LED), a light emitting diode (LED) mounted in a package or a member integrated with a member having a lens function can be used. Instead of the aluminum base printed board, other high heat conductive materials such as a metal plate such as copper or stainless steel or a ceramic board such as aluminum nitride can be used as the heat radiating board. As a means for adhering the LED chip to the heat dissipating substrate, other means such as a conductive paste such as silver paste or solder can be used instead of the heat dissipating grease. The structure of the circuit board is not limited to the structure shown in FIG. As a method of mounting the LED chip on the substrate, face-down connection using bumps or anisotropic conductive material can be used instead of face-up connection by wire bonding. The reflector can use a metal with high light reflectance other than aluminum or a white resin material. Fixing the reflector to the circuit board and fixing the light guide plate on the reflector can be mechanically fixed by screws or the like instead of the adhesive. As the sealing material, an epoxy resin can be used in addition to the silicone resin.

It is a figure which shows the whole structure of the liquid crystal display device with which this Embodiment is applied. It is a schematic sectional drawing of the surface light source device by one Embodiment of this invention. It is a schematic sectional drawing of the surface light source device by another embodiment of this invention. It is a schematic sectional drawing of the surface light source device by another embodiment of this invention. It is a schematic sectional drawing of the surface light source device by another embodiment of this invention. It is a schematic sectional drawing of the surface light source device by another embodiment of this invention. It is a figure which shows an example of the printing pattern formed in the light guide member upper surface. It is a figure which shows the arrangement | sequence of the LED chip on the aluminum base printed circuit board (LED light source) in an Example. It is a figure which shows the arrangement | sequence of the aluminum base printed circuit board (LED light source) on the aluminum housing bottom surfaces in an Example. It is the schematic sectional drawing cut | disconnected by AA of FIG. It is a schematic sectional drawing of the conventional liquid crystal display panel and the direct type | mold surface light source device arrange | positioned directly under it.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Surface light source (backlight) apparatus 11 ... Backlight frame (housing | casing)
12 ... LED board (mounting board)
12a..Recess 13 on the upper surface of the LED substrate (mounting substrate)... Light emitting diode (LED)
14 ... Light guide member (plate or film)
14a..Concavity 15 of light guide member (plate or film) ... Diffusion member (plate or diffusion film)
16 ... Prism sheet 17 ... Prism sheet 18 ... Reflective member (plate, film (coating film))
20 ... Heat dissipation substrate (aluminum substrate)
21 ... Circuit board 22 ... Aluminum base printed board 23 ... Light emitting diode (LED)
23R ... Red light emitting diode (LED)
23G ・ ・ Green light-emitting diode (LED)
23B ... Blue light emitting diode (LED)
24: Light guide member (plate or film)
25 ... Case 26 ... Circuit board opening 27 ... Sealing resin 28 ... Reflector 30 ... Liquid crystal display module 31 ... Liquid crystal panel 32 ... Polarizing plate (polarizing filter)
33 ... Polarizing plate (polarizing filter)
DESCRIPTION OF SYMBOLS 101 ... Liquid crystal panel 102 ... Surface light source device 103 ... Light emitting diode (LED)
104 ... Case 105 ... Reflection sheet 106 ... Diffusion plate 107 ... Lens sheet (prism sheet)

Claims (10)

A substrate on which a solid light emitting element is mounted; a light guide member disposed opposite to the upper side of the substrate; and a reflection member disposed on a lower surface of the light guide member; A surface light source device having a recess on at least one surface.   The surface light source device according to claim 1, wherein the concave portion is provided at a position immediately above the solid state light emitting device.   The surface light source device according to claim 1, wherein the shape of the recess is a cone, a pyramid, a cylinder, a prism, or a hemisphere.   The surface light source device according to claim 1, wherein the concave portion is provided on a lower surface of the light guide member.   The surface light source device according to claim 1, wherein dots for light scattering are provided on a lower surface of the light guide member.   The surface light source device according to claim 1, wherein the solid-state light emitting element includes a red solid-state light emitting element, a green solid-state light emitting element, and a blue solid-state light emitting element.   On the surface of the light guide member, the distance from the position immediately above each solid light emitting element to the nearest light scattering dot is larger than the distance from the solid light emitting element to the nearest solid light emitting element. The surface light source device according to claim 5 or 6, characterized in that   A concave portion is provided on the upper surface of the substrate, and the solid-state light emitting element is installed in the concave portion so that the upper end thereof is located below the upper surface of the substrate. The surface light source device according to any one of the above.   A display device comprising the surface light source device according to claim 1.   The display device according to claim 9, wherein the display unit is a liquid crystal panel.

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