JP2013058353A - Light source module and liquid crystal display device having the same - Google Patents

Abstract

A light source module capable of increasing the coupling efficiency from a light source to a light guide plate without reducing the processing of the light guide plate and reducing luminance unevenness of the light guide plate, and a liquid crystal display device including the same.
An LED chip 23a, a light guide plate 13, and an optical coupling member 30 that guides light from the LED chip 23a to the light guide plate 13. The light coupling member 30 includes a top flat surface 31 that allows light to enter the light guide plate 13 side, two side surfaces located on both sides of the top flat surface 31, and a light incident surface that receives light from the LED chip 23 a. 33a. One of the two side surfaces is a reflection surface that reflects light from the light incident surface 33a positioned below the curved surface 32a and guides it to the top flat surface 31, while At least a part of the surface of the other side surface portion 36 that is the other side surface portion including the boundary with the top flat surface 31 is rougher than the reflecting surface.
[Selection] Figure 1

Description

  The present invention relates to a light source module and a liquid crystal display device including the same, and the light source module is applied to, for example, a backlight of a liquid crystal display device or indoor or outdoor illumination.

  In recent years, in order to reduce the thickness of a liquid crystal display device, a backlight including a side edge (also referred to as a sidelight) type light guide plate that emits light from a light source in a planar shape by a light guide plate is frequently used.

  In such a side-edge type light guide plate, light sources such as LEDs (Light Emitting Diodes) are arranged at both ends in the longitudinal direction of the light guide plate, and light is incident from each end face in the longitudinal direction of the light guide plate. The light is emitted to the surface of the light guide plate while totally reflecting the light toward the inner center of the light guide plate.

  However, in the side edge type light guide plate, the light guide plate expands and contracts due to thermal expansion, and in particular, the amount of expansion and contraction is large in the longitudinal direction of the light guide plate. For this reason, at the edge part of a light-guide plate, a light source cannot be closely_contact | adhered to a light-guide plate, but it has a structure which has the clearance | gap which anticipated the expansion-contraction amount by thermal expansion. As a result, there is a problem that the incidence efficiency of the light source to the light guide plate is deteriorated due to the presence of the gap. The problem is that the larger the liquid crystal display device, that is, the larger the light guide plate, the greater the amount of expansion and contraction. Therefore, the gap between the light source and the light guide plate must be increased. Is further reduced.

  Therefore, in order to solve this problem, in the backlight 100 for a display device disclosed in Patent Document 1, as shown in FIG. 13, the light emitting diode 101 is provided below the light guide plate 110 and the optical axis thereof is the light guide plate 110. It is provided so as to be orthogonal to. Then, immediately above the light emitting diode 101 on the surface of the light guide plate 110, curved reflecting surfaces 111 and 111 are formed so as to reflect the light from the light emitting diode 101 toward both ends of the light guide plate 110. A reflective sheet 102 is provided below the light emitting diode 101.

  With the above configuration, the light guide plate 110 can be disposed close to the light guide plate 110 because the light guide plate 110 does not have a large amount of expansion and contraction in the thickness direction. In addition, in combination with the presence of the reflection sheet 102 provided on the lower side of the light emitting diode 101, substantially all of the light emitted from the light emitting diode 101 is introduced into the light guide plate 210. As a result, it is possible to improve the coupling efficiency of light to the light guide plate 110 and the light utilization efficiency as compared with the side edge (also referred to as side light) type light guide plate.

  In addition, since it is necessary to process a light-guide plate in the backlight 100 for display apparatuses of patent document 1, there exists a fault which becomes high cost rather than a simple flat light-guide plate. In addition, since the luminance immediately above the light emitting diode 101 becomes brighter than the surroundings and bright lines are generated, there is a disadvantage that a uniform luminance distribution cannot be created.

  Here, the general direct type is a system in which LEDs are arranged in a matrix under the liquid crystal panel to uniformly irradiate the liquid crystal panel. In addition, the direct type includes a method in which light emitted from the LED is spread using a LED and a diffusion lens (a lens that diffuses light) to uniformly irradiate the liquid crystal panel.

JP 2006-49324 A (published February 16, 2006)

  However, the conventional light source module disclosed in Patent Document 1 has a problem that the light guide plate needs to be processed, so that the cost is higher than that of a simple flat light guide plate.

  In addition, since the luminance immediately above the light emitting diode 101 becomes brighter than the surroundings and bright lines are generated, there is a disadvantage that a uniform luminance distribution cannot be created.

  Further, when the relative position between the light source and the light guide plate is shifted due to manufacturing variations, luminance unevenness occurs.

  The present invention has been made in view of the above-described conventional problems, and its object is to increase the coupling efficiency from the light source to the light guide plate without reducing the light guide plate, and to reduce the luminance unevenness of the light guide plate. It is an object to provide a light source module to be obtained and a liquid crystal display device including the same.

  In order to solve the above problems, the light source module of the present invention is a light source module including a light source, a light guide plate, and an optical coupling member that guides light from the light source to the light guide plate. A top flat portion for entering light on the light guide plate side, two side portions located on both sides of the top flat portion, and a light incident portion for receiving light from the light source. One surface of the side surface portion is a reflection surface that reflects light from the light incident portion located below the curved surface and guides it to the top flat portion, while the other of the two side surface portions. At least a part of the surface including the boundary with the top flat portion is formed to be rougher than the reflecting surface.

  According to the above invention, the light emitted from the light source below the light guide plate enters the light coupling member from the light incident portion, is reflected by the curved surface of the light coupling member, and enters the light guide plate from the top flat portion. Is done. While the light incident on the light guide plate is totally reflected inside the light guide plate, a part of the light propagates to the end of the light guide plate, and the total reflection condition is broken by an optical path conversion element in the middle of the light. The light is emitted from the upper surface of the light guide plate.

  As a result, unlike the conventional side edge type light guide plate, since it is a backlight directly under the light guide plate, a light source and a light guide plate for avoiding thermal expansion required in the side edge type light guide plate, Thus, the coupling efficiency from the light source to the light guide plate can be increased, and the light utilization efficiency can be improved.

  Further, in the present invention, since the light coupling member separate from the light guide plate is provided so that light is incident from the incident portion on the lower surface of the light guide plate, the incident light is guided while being totally reflected inside the light guide plate. The As a result, it is not necessary to process the light guide plate, the coupling efficiency from the light source to the light guide plate can be increased, the light utilization efficiency can be improved, and the manufacturing cost is also reduced.

  By the way, in the light source module having such a structure, when the positional relationship between the optical coupling member and the light source is deviated from a predetermined position, the light source is more specifically shifted to the leg part side than the predetermined position with respect to the optical coupling member. And a part of the light reflected from the reflecting surface made of a curved surface is not coupled to the top flat portion of the optical coupling member, and is emitted from the other surface of the two side surfaces opposite to the reflecting surface made of the curved surface. To become stray light. The amount of stray light generated increases as the stray light shifts to the other surface side of the two side surfaces from the predetermined position with respect to the optical coupling member.

  When such stray light enters the light guide plate, luminance unevenness occurs in the light guide plate.

  Therefore, in the present invention, at least a part of the other surface of the two side portions of the optical coupling member including the boundary with the top flat portion is formed to be rougher than the reflecting surface. As a result, the light that has reached the other surface of the two side surface portions causes irregular reflection on the rough surface, and therefore does not enter the light guide plate.

  Therefore, it is possible to provide a light source module that can increase the coupling efficiency from the light source to the light guide plate and reduce the uneven brightness of the light guide plate without processing the light guide plate.

  In the light source module of the present invention, at least a portion including the boundary with the top flat portion on the other surface of the two side surfaces of the optical coupling member has a surface roughness Ra ≧ 0.2. can do.

  As a result, the light that has reached the other surface of the two side surfaces is surely irregularly reflected by the rough surface, so that it does not enter the light guide plate.

  In the light source module of the present invention, the reflection surface, which is one of the two side surfaces of the optical coupling member, may have a surface roughness Ra <0.2.

  As a result, the reflection surface made of a curved surface of the optical coupling member surely totally reflects and enters the light guide plate from the top flat portion of the optical coupling member.

  In the light source module of the present invention, the optical coupling member may have an arch shape or a semicircular shape in cross section.

  Accordingly, it is possible to reflect most of the light incident from the light source located below the optical coupling member via the light incident portion on the curved surface and guide it to the top flat portion. Further, in the optical coupling member having a cross-sectional arch shape or semicircular shape, the outer shape surface shape is symmetrical, so that there is an advantage that a mold can be easily formed.

  In order to solve the above-described problems, a liquid crystal display device according to the present invention includes the light source module described above as a backlight.

  According to said invention, a liquid crystal display device provided with the light source module which can improve the coupling efficiency from a light source to a light guide plate, and can reduce the brightness nonuniformity of a light guide plate, without accompanying the process of a light guide plate can be provided. .

  As described above, in the light source module of the present invention, the light coupling member has a top flat portion that allows light to enter the light guide plate side, two side portions located on both sides of the top flat portion, and light from the light source. A light incident portion that is incident on the surface, and one surface of the two side surface portions reflects light from the light incident portion located below the curved surface to be guided to the top flat portion. On the other hand, at least a part of the other surface of the two side portions including the boundary with the top flat portion is formed to be a rougher surface than the reflective surface.

  As described above, the liquid crystal display device of the present invention includes the light source module described above as a backlight.

  Therefore, there is an effect of providing a light source module capable of increasing the coupling efficiency from the light source to the light guide plate without reducing the processing of the light guide plate and reducing the luminance unevenness of the light guide plate, and a liquid crystal display device including the same. .

1 illustrates an embodiment of a light source module according to the present invention, and is an optical path that scatters on the surface of a leg portion when incident light from an LED chip is not coupled to a light guide plate in an optical coupling member provided in the light source module. FIG. It is a disassembled perspective view which shows the structure of the liquid crystal display device provided with the said light source module. (A) is sectional drawing which shows the whole structure of the said liquid crystal display device, (b) is sectional drawing which shows the structure of the light source unit in the liquid crystal display device shown to (a). It is a perspective view which shows the structure of the light source module in the said liquid crystal display device. It is a disassembled perspective view which shows the structure of the light source unit in the said light source module. It is a top view which shows the structure of the LED board in the said light source unit. (A) is sectional drawing which shows the optical path when the light radiate | emitted from the LED chip injects into a light-guide plate via the optical coupling member which has a paraboloid, (b) is principal part sectional drawing which shows the LED chip vicinity. It is. It is a perspective view which shows the structure of the light source module which removed the said light-guide plate. It is sectional drawing cut | disconnected by the cut surface S in FIG. It is sectional drawing which expands and shows the principal part structure by the side of A of FIG. (A) is explanatory drawing which shows the optical path of the optical coupling member for demonstrating the generation | occurrence | production principle of a stray light, (b) is a top view which shows the luminance distribution of a light-guide plate. (A) is a front view which shows the structure of a liquid crystal display device, (b) is the side view. It is sectional drawing which shows the structure of the conventional light source module.

  An embodiment of the present invention will be described below with reference to FIGS.

(Overall configuration of liquid crystal display device)
A configuration of a liquid crystal display device including the light source module of the present embodiment will be described with reference to FIG. FIG. 2 is an exploded perspective view showing the configuration of the liquid crystal display device of the present embodiment.

  As shown in FIG. 2, the liquid crystal display device 1 of the present embodiment includes a backlight 10 as a light source module, a diffusion plate 2A, a prism sheet 3, a diffusion sheet 2B, a liquid crystal panel 4, and a bezel 5 stacked in this order. Has been placed. In the liquid crystal display device 1, the light emitted from the backlight 10 passes through the diffusion plate 2 </ b> A, the prism sheet 3, and the diffusion sheet 2 </ b> B and enters the liquid crystal panel 4. A desired image is displayed by partially changing the light transmittance in the liquid crystal panel 4. The liquid crystal panel 4 has a rectangular flat plate shape, and the diffusion plate 2A, the prism sheet 3 and the diffusion sheet 2B have substantially the same shape as the liquid crystal panel 4. Here, the direction parallel to the long side of the liquid crystal panel 4 is defined as the X direction, the direction parallel to the short side of the liquid crystal panel 4 is defined as the Y direction, and the direction perpendicular to both the X direction and the Y direction is defined as the Z direction. To do. The X direction is also referred to as the longitudinal direction. The Z direction can also be said to be the normal direction of the liquid crystal panel 4.

(Backlight configuration)
As illustrated in FIG. 2, the backlight 10 includes a light source unit 20, a chassis 11 having a single opening 11 a, and a single opening 12 a similar to the chassis 11, in order from the bottom, that is, in order from the far side from the liquid crystal panel 4. And a light guide plate 13 as an optical member. The chassis 11 is made of, for example, a material such as iron, and increases the strength of the backlight 10. The chassis 11 is formed in a rectangular shape that is substantially the same size as the liquid crystal panel 4.

  The light source unit 20 includes a light source holder 21 having a recess 21a. The recess 21a is a long or strip-like groove extending in the X direction. The light source holder 21 is disposed on the end side along the long side direction of the liquid crystal panel 4.

  The reflection sheet 12 is provided to reflect the light leaking from the light guide plate 13 and return it to the light guide plate 13. The reflection sheet 12 is divided into two parts at a portion where an optical coupling member 30 as an optical member, which will be described later, in the light source unit 20 contacts the light guide plate 13, and a single opening 12 a is formed between the two divided reflection sheets. Is formed. That is, on the lower surface of the light guide plate 13 on the light source unit 20 side, there are a region in contact with the optical coupling member 30 and a region in which the reflection sheet 12 is provided. Then, the light enters the light guide plate 13 through a region of the light guide plate 13 that contacts the optical coupling member 30.

  The light guide plate 13 is for guiding incident light to the liquid crystal panel 4 side, and has a flat plate shape.

(Configuration of light source unit)
Next, the structure of the light source unit 20 will be described with reference to FIGS. 3 (a) and 3 (b) and FIGS. 4 to 7 (a) and 7 (b). FIG. 3A is a cross-sectional view showing the overall configuration of the liquid crystal display device 1, and FIG. 3B is a cross-sectional view showing the configuration of the light source unit in the liquid crystal display device 1. FIG. 4 is a perspective view showing the configuration of the backlight in the liquid crystal display device 1. FIG. 5 is an exploded perspective view showing the configuration of the light source unit in the backlight. FIG. 6 is a plan view showing the configuration of the LED substrate in the light source unit. FIG. 7A is a cross-sectional view showing an optical path when light emitted from the LED chip enters the light guide plate through an optical coupling member having a paraboloid, and FIG. 7B shows the vicinity of the LED chip. It is principal part sectional drawing.

  As shown in FIGS. 3A and 3B, the light source unit 20 includes an LED substrate 24a as a light source substrate on which an LED (Light Emitting Diode) chip as a light source is mounted, and a long shape. The optical coupling member 30 and the heat sink 22 are provided. The light coupling member 30 is an optical element for coupling light emitted from the LED chip and causing the light to enter the light guide plate 13 at a predetermined angle. Moreover, the LED board 24a and the optical coupling member 30 are mounted on the heat sink 22 as a plate-like member. Further, the light guide plate 13, the optical coupling member 30, the LED substrate 24a, and the heat sink 22 are arranged in this order. Since the semiconductor LED chip has a very fine size, FIGS. 3 (a) and 3 (b) to FIG. 5 omit the description for preventing complexity of the drawings.

  As shown in FIG. 4, the optical coupling member 30 is made of a translucent member whose cross section in the X direction has a bifurcated shape (arch shape). And one side of this forked shape is arrange | positioned on LED board 24a. Moreover, the optical coupling member 30 has a top flat surface on the opposite side to the LED substrate 24a, and the light guide plate 13 is fixed to the top flat surface. Note that the optical coupling member 30 is not necessarily limited to the cross-sectional arch shape, and may be a semi-circular cross-sectional shape.

  The light emitted from the LED chip on the LED substrate 24 a enters from one of the bifurcated light incident surfaces of the optical coupling member 30, propagates through the optical coupling member 30, and is a top portion that is a fixed portion to the light guide plate 13. It is optically coupled to the light guide plate 13 on a flat surface. That is, the light enters the light guide plate 13. The light incident on the light guide plate 13 propagates in the Y direction while being totally reflected inside the light guide plate 13, and a part of the light is transmitted by a light scatterer that is a light extraction unit formed on the back surface of the light guide plate 13. The total reflection condition is broken, and the light is emitted from the surface of the light guide plate 13 to the arrow La that is above the Z direction. The light scatterer is a minute pattern formed on the back surface of the light guide plate 13 by printing or the like. In this way, the light source unit 20 can emit light from the LED chip from almost the entire surface of the light guide plate 13, and thus can be used as a surface light emitting device. The detailed behavior of light from the LED chip to the light guide plate 13 in the light source unit 20 will be described later.

  In the present embodiment, an LED chip is used as a light source. This is because a semiconductor chip-shaped LED has a small shape and can be arranged in a narrow region. Thereby, even when an inexpensive low-power LED chip is used, the illuminance is improved by disposing a large number of LEDs at close intervals, which is preferable in that it can be used as a high-function backlight light source. However, the present invention is not limited to this. For example, an LED housed in a package may be used, and an organic EL light emitting element or an inorganic EL light emitting element may be used.

  As shown in FIG. 5, a dam 26a made of a white resin is formed on the surface of the LED substrate 24a. As shown in FIG. 6, the dam 26 a is formed long in the width direction (longitudinal direction) of the liquid crystal display device 1. Moreover, the dam 26a is formed in the recessed shape (refer FIG. 10 mentioned later). In the dam 26a, as shown in FIG. 6, the LED chips 23a are arranged in a row at intervals of, for example, several mm in the longitudinal direction of the dam 26a. An alignment mark 27a for adjusting the position with the optical coupling member 30 is provided on the outer periphery of the dam 26a. The alignment mark 27a is prepared in advance on the LED substrate 24a in order to define the mounting position of the LED chip 23a. The LED board 24a is a so-called printed wiring board, and is made of a material such as alumina, ceramic, or glass epoxy resin. The thickness of the LED substrate 24a is 2 mm, for example.

  Further, although not shown in FIG. 6, the dam 26a is filled with a transparent resin for sealing the plurality of LED chips 23a. And this transparent resin contains the fluorescent substance. The same type of phosphor is used for each LED chip 23a.

  Also, boss holes 28a and 28a are formed in the LED substrate 24a. The boss holes 28a and 28a are holes for inserting bosses 35a and 35a described later (see FIG. 8 described later).

  As shown in FIGS. 4 and 5, the optical coupling member 30 has a substantially U-shaped cross section perpendicular to the X direction, that is, a tunnel shape or an arch shape, and is a rod-like body that is long in the X direction. And it is provided between the light guide plate 13 and the LED chip 23a.

  As a result, the liquid crystal display device 1 of the present embodiment includes a liquid crystal panel 4, a light guide plate 13 that irradiates light to the liquid crystal panel 4, an optical coupling member 30 as an optical member that couples light to the light guide plate 13, The light coupling member 30 includes an LED chip 23a that emits incident light, and the liquid crystal panel 4, the light guide plate 13, the light coupling member 30, and the LED chip 23a are arranged in this order. The backlight 10 in the liquid crystal display device 1 is a backlight 10 directly under the light source in which the LED chip 23 a is provided below the light guide plate 13. The LED chips 23 a are arranged so that the optical axis direction of the emitted light, that is, the direction with the highest luminance in the incident light is orthogonal to the flat light guide plate 13.

  Moreover, in this Embodiment, the liquid crystal display device 1 raises the optical coupling efficiency from the LED chip 23a as a light source to the light-guide plate 13, without accompanying the technical idea of processing of a light-guide plate, and improves light utilization efficiency. obtain. Hereinafter, the detailed structure and optical path of the optical coupling member 30 will be described.

  As described above, the optical coupling member 30 is formed of a strip-like body having a substantially U-shaped cross section, that is, a rod-like body, provided between the light guide plate 13 and the LED chip 23a. The material of the optical coupling member 30 is made of the same resin as that of the light guide plate 13. Since the refractive index can be made the same if they are the same material, the light is smoothly incident on the light guide plate 13 from the optical coupling member 30. The refractive index of the light guide plate 13 may be slightly higher than the refractive index of the optical coupling member 30. Further, the material is not limited to resin, and a material such as glass may be used.

  Specifically, as shown in FIG. 7A, the surface of the optical coupling member 30 on the light guide plate 13 side has a top flat surface 31 as a top flat portion that abuts the flat light guide plate 13, and a curved surface 32 a. 32b. The curved surfaces 32a and 32b are formed so as to extend away from the light guide plate 13 from the top flat surface 31 to both ends. The curved surface 32a functions as a reflective surface of one surface of the two side surfaces of the optical coupling member 30 in the present invention, and the curved surface 32b is a function of the two side surfaces of the optical coupling member 30 in the present invention. It functions as the other surface.

  The curved surfaces 32a and 32b can be, for example, a cross-sectional parabola shown in FIG. That is, the curved surfaces 32a and 32b form a parabola in the cross-sectional shape of the optical coupling member 30 perpendicular to the longitudinal direction (X direction) of the liquid crystal panel 4. However, the shape is not necessarily limited thereto, and may be a curved shape such as an elliptical cross section or a bow shape, or a flat surface inclined obliquely from the top flat surface 31 as long as it can effectively couple light to the light guide plate. Absent. Thereby, the optical coupling member 30 functions to propagate the light emitted from the light source while being bent inside the optical coupling member and to make the light incident on the flat light guide plate 13 obliquely. For this reason, most of the light from the light source can be coupled to the light guide plate 13.

  The surface of the optical coupling member 30 opposite to the light guide plate 13 side, that is, the lower end of the optical coupling member 30 is two lower flat surfaces. One of the two lower flat surfaces is a light incident surface 33a for receiving light from the LED chip 23a. The LED chip 23a is disposed directly below the light incident surface 33a. A spacer 25a having a height of about 0.5 mm is formed on a part of the light incident surface 33a to prevent the LED chip 23a from being damaged due to the collision between the LED chip 23a and the optical coupling member 30. The LED chip 23a is bonded to the LED substrate 24a. That is, the LED chip 23a is bonded and fixed to the LED substrate 24a by applying an adhesive or the like in the vicinity of the spacer 25a.

  Further, a recess 34 is formed in the central portion on the lower end side of the optical coupling member 30. However, the present invention is not necessarily limited to this, and a cross-sectionally semi-cylindrical shape or a semicircular cross-sectional shape in which the recess 34 does not exist may be used. That is, in the present embodiment, it is only necessary to secure an optical path to the light guide plate 13 for light reflected by the curved surface 32a, so that a portion that does not become an optical path can be cut out as a recess 34. Thereby, cost reduction can be aimed at. In addition, it is also possible to provide reflection means such as a reflection sheet (not shown) in the recess 34. Thereby, even if the stray light generated in the vicinity of the top flat surface 31 may occur, a part of the stray light can be reflected to the light guide plate 13 side to improve the irradiation to the liquid crystal panel 4.

  Below the light incident surface 33a of the optical coupling member 30, an LED chip 23a bonded to the LED substrate 24a is provided in proximity. As shown in FIG. 7B, the LED chip 23a is preferably present on the end side with respect to the focal position F of the curved surface 32a made of a parabolic cross section, for example. 7A, for example, light emitted from the LED chip 23a enters the light incident surface 33a of the optical coupling member 30 and is reflected by the curved surface 32a having a parabolic cross section. Then, the reflected light reaches the top flat surface 31 of the optical coupling member 30 and enters the light guide plate 13 obliquely while maintaining the arrival direction. The light incident on the light guide plate 13 is reflected on the right side of the light guide plate 13 shown in FIG. The angle of traveling through the light guide plate 13 is changed by colliding with a light scatterer that is an optical path changing unit. And according to the advancing angle, it becomes the light by which the total reflection conditions were violated, and the light which satisfies the total reflection conditions. The light whose total reflection condition is broken is emitted from the surface of the light guide plate 13 on the liquid crystal panel 4 side, and travels toward the liquid crystal panel 4 through the diffusion sheet 2B and the prism sheet 3. On the other hand, light that satisfies the total reflection condition is not emitted from the light guide plate 13 but is reflected by the reflection sheet 12 and is reflected by the reflection sheet 12 and totally reflected inside the light guide plate 13 (Y direction in FIG. 4). The angle of traveling through the light guide plate 13 is changed by colliding with a light scatterer that is an optical path changing unit.

  That is, the light incident on the light guide plate 13 is totally reflected inside the light guide plate 13 and travels toward the end portion, so that the light scattering body provided on the back surface of the light guide plate 13 acts on the liquid crystal panel 4 side of the light guide plate 13. Light with broken total reflection conditions on the surface is generated, and this light is emitted from the light guide plate 13. On the other hand, light satisfying the total reflection condition is totally reflected from the inside of the light guide plate 13 toward the end, and is emitted from the light guide plate 13 again by the action of the light scatterer provided on the back surface of the light guide plate 13 in this optical path. Light is generated. As described above, in the light source unit 20, the light is reflected to the outside of the light guide plate 13 by changing the angle at which the incident light travels by providing a light scatterer in the light path in which the incident light is totally reflected and travels toward the end. Is emitted.

  Such an optical path is the same in the optical coupling member 30 having the curved surface 32a having an elliptical cross section. And also in the optical coupling member 30 with a cross-sectional ellipse, it is preferable that the LED chip 23a exists in the edge part side rather than the focus position F of the curved surface 32a which consists of a cross-sectional ellipse, for example.

(Fixing of LED board and optical coupling member)
Next, fixing of the LED substrate 24a and the optical coupling member 30 according to the present embodiment will be described with reference to FIGS. FIG. 8 is a perspective view showing a configuration in which the light guide plate 13 in the light source unit 20 is removed. FIG. 9 shows a cross-sectional view of the configuration of FIG. FIG. 10 is an enlarged cross-sectional view showing the main configuration of the A side in the configuration of FIG.

  As shown in FIGS. 8 to 10, the optical coupling member 30 is elongated in the X direction, and the cross section perpendicular to the X direction has a bifurcated shape (substantially U-shaped cross section) rooted at the top flat surface 31. Is the body. A crotch portion extending from the top flat surface 31 to the A side (one side) is disposed on the LED substrate 24a. The LED substrate 24a is screwed to the heat sink 22 by screws 34a.

  Two bosses 35a and 35a 'for fixing the light coupling member 30 and the LED substrate 24a are provided in a portion of the light coupling member 30 facing the LED substrate 24a. These bosses 35a and 35a 'are inserted into the boss holes 28a and 28a of the LED substrate 24a. The bosses 35a and 35a 'are assigned to a boss 35a bonded and fixed to the LED board 24a and a boss 35a' detachably attached to the LED board 24a. That is, of the bosses 35a and 35a ', only the boss 35a is inserted into the boss hole 28a of the LED substrate 24a and fixed with an adhesive or the like. On the other hand, the boss 35a 'is only inserted into the boss hole 28a of the LED substrate 24a.

  Further, as shown in FIG. 9, the heat sink 22 is provided with a through hole 22a communicating with the boss hole 28a of the LED substrate 24a thereon. The through hole 22a is a hole for accommodating the bosses 35a and 35a 'penetrating the boss hole 28a of the LED substrate 24a, and is a portion where excess adhesive is accumulated. The through hole 22a penetrates the heat sink 22 and is used for repair.

  No LED substrate is disposed on the B side (the other side) with respect to the top flat surface 31 of the optical coupling member 30. Two bosses 35 b and 35 b ′ for fixing the optical coupling member 30 and the heat sink 22 are provided in a portion facing the heat sink 22 at the crotch portion extending from the top flat surface 31 to the B side. As shown in FIG. 9, the heat sink 22 is provided with through holes 22b and 22b for inserting the bosses 35b and 35b '. These bosses 35 b and 35 b ′ are assigned to a boss 35 b that is bonded and fixed to the heat sink 22 and a boss 35 b ′ that is detachably attached to the heat sink 22. That is, of the bosses 35b and 35b ', only the boss 35b is inserted into the through hole 22b of the heat sink 22 and fixed with an adhesive. The through hole 22b of the heat sink 22 is used for repair.

  A top flat surface 31 is formed at a portion of the optical coupling member 30 that faces the light guide plate 13. The light guide plate 13 is fixed in contact with the top flat surface 31. The top flat surface 31 is a portion that couples light from the LED substrate 24 a to the light guide plate 13.

  As shown in FIG. 8, a spacer 25 a is provided at the crotch portion of the optical coupling member 30 that extends from the top flat surface 31 toward the A side. The spacer 25a is provided to maintain a clearance between the light incident surface 33a of the light coupling member 30 and the LED substrate 24a. In addition, a spacer 25 b that contacts the heat sink 22 is provided at the crotch portion that extends from the top flat surface 31 to the B side. Since it is necessary to maintain the parallelism between the light incident surface 33a of the light coupling member 30 and the LED substrate 24a, the spacer 25b is higher than the spacer 25a by the thickness of the LED substrate 24a.

  Also, as shown in FIG. 10, a plurality of LED chips 23a are arranged inside the annular dam 26a at the joint portion of the LED substrate 24a and the optical coupling member 30. This LED chip is disposed outside the spacer 25a. The LED chip 23a is separated from the optical coupling member 30 by the spacer 25a. The spacer 25a prevents the LED chip 23a from being damaged due to the collision between the LED chip 23a and the optical coupling member 30. That is, the presence of the spacer 25a makes it possible to dispose the LED chip 23a between the LED substrate 24a and the light incident surface 33a of the light coupling member 30 and to provide a gap that does not damage the LED chip 23a.

  Thus, the LED chip 23a is fixed to the optical coupling member 30 via the LED substrate 24a, the spacer 25a, and the adhesive. As a result, the LED chip 23a and the optical coupling member 30 are integrated.

  The transparent resin that seals the LED chip 23a is blocked by the dam 26a, and the cured product forms the light emitting portion 23c. The light emitted from the LED chip 23a is wavelength-converted by the transparent resin cured product. For this reason, the whole light emission part 23c light-emits. The clearance between the light emitting part 23c and the light incident surface 33a of the optical coupling member 30 is set to 0.1 mm, for example. And this clearance is ensured by the above-mentioned spacer 25a. Further, the light emitted from the LED chip 23 a enters the light incident surface 33 a, propagates inside the optical coupling member 30, is totally reflected by the curved surface 32 a, reaches the top flat surface 31, and enters the light guide plate 13. To do. An arrow Lb shown in FIG. 10 shows an example of a typical optical path from the LED chip 23a toward the light guide plate 13.

  Moreover, the following dimension is mentioned as an example of the dimension of the junction part in LED board 24a and the optical coupling member 30. FIG. That is, the width of the dam 26a in the Y direction is 1.5 mm, the thickness of the LED substrate 24a is 2 mm, the width of the light emitting portion 23c in the Y direction is 0.65 mm, the light incident portion 33c and the light incident surface 33a of the optical coupling member 30 The clearance between them is 0.1 mm.

(Surface roughness of the curved surface of the optical coupling member)
In the present embodiment, one of the two side surfaces hanging down toward both sides of the top flat surface 31 of the optical coupling member 30 reflects light from the light incident surface 33a positioned below the curved surface 32a. The curved surface 32b which is the surface of the other side surface portion 36 which is the other side surface portion of the two side surface portions includes at least a boundary with the top flat surface 31. A part is formed to be rougher than the reflecting surface. The reason for this will be described with reference to FIGS. 11 (a) and 11 (b). FIG. 11A is an explanatory view showing the optical path of the optical coupling member for explaining the principle of stray light generation, and FIG. 11B is a plan view showing the luminance distribution of the light guide plate.

  As shown in FIG. 10, the light emitting portion 23c provided on the LED substrate 24a on the lower side of the optical coupling member 30 is configured by the LED chip 23a and a transparent resin body that seals the LED chip 23a. And has a width of 0.65 mm. The width of the light emitting portion 23c varies in manufacturing. Further, the relative mounting position of the LED substrate 24a and the optical coupling member 30 also varies in manufacturing.

  Here, as shown in FIG. 11 (a), when the positional relationship between the light coupling member 30 and the LED chip 23a is shifted from a predetermined position, the light incident on the light coupling member 30 is flat at the top. In some cases, the light does not reach the surface 31 and becomes stray light. In particular, when the light emitting part 23c is attached to the optical coupling member 30 so as to be displaced relative to the inner side (the inner side of the fork), it passes through the path indicated by the arrow Lc in the drawing and does not reach the top flat surface 31 The light escapes from the side of the curved surface 32b facing the curved surface 32a, resulting in light leakage. That is, the curved surface 32b in the other side surface portion 36 of the optical coupling member 30 does not have a function as a reflecting surface. For this reason, when the position shift of the LED chip 23a occurs, when the light reflected by the reflecting surface made of the curved surface 32a deviates from the top flat surface 31, a part of the reflected light is reflected on the opposite side surface. It comes into contact with the curved surface 32b of the other side surface portion 36. And the place becomes the boundary part vicinity near the top flat surface 31 among the curved surfaces 32b of the other side surface part 36.

  For this reason, the light that has escaped from the curved surface 32b enters the light guide plate 13 from the lower side of the light guide plate 13 and becomes stray light. More specifically, the reflective sheet 12 is provided on the lower side of the light guide plate 13, but the gap is formed between the light guide plate 13 and the reflective sheet 12 (for example, a gap is generated due to sagging of the reflective sheet 12). The light beam is guided, and further, the light beam reflected by the reflection sheet 12 passes through the light guide plate 13 and is guided to the liquid crystal panel 4 to cause light leakage.

  Such a behavior becomes prominent when the light emitting portion 23c is attached to the optical coupling member 30 so as to be displaced relative to the inner side (the inner side of the fork).

  When the light source module with stray light generated in this way is applied to the backlight of the liquid crystal display device 1 or the like, luminance unevenness due to stray light occurs on the surface of the liquid crystal display device 1 as shown in FIG. It becomes.

  Therefore, in the backlight 10 of the present embodiment, as shown in FIG. 1, a curved surface 32b, that is, a curved surface 32b opposite to the light incident surface side A of the optical coupling member 30 is formed on the rough surface. That is, the curved surface 32a on the light incident surface side A of the optical coupling member 30 is a mirror surface with a surface roughness Ra <0.2, while the curved surface 32a of the optical coupling member 30 is the opposite surface of the curved surface 32a. The curved surface 32b of the other side surface portion 36 is a rough surface with a surface roughness Ra ≧ 0.2. Therefore, the surface roughness of the curved surface 32b of the other side surface portion 36 is rougher than the surface roughness of the curved surface 32a.

  From the viewpoint of light reflection / diffusion, the curved surface 32a on the light incident surface side A of the optical coupling member 30 is preferably a mirror surface with a surface roughness Ra = 0.05, and the other side surface portion 36 of the optical coupling member 30 is used. The curved surface 32b is preferably a rough surface having a surface roughness Ra ≧ 0.4.

  As a result, light of a path such as an arrow Lc generated when the light emitting unit 23c is attached with being relatively displaced with respect to the optical coupling member 30 is scattered by the rough surface of the curved surface 32b, and the optical coupling member 30 from the curved surface 32b. The light that escapes outside can be reduced. Specifically, the light is scattered in various directions before the light is guided to the gap between the light guide plate 13 and the reflection sheet 12. Thereby, much of the light that causes light leakage is not guided to the gap between the light guide plate 13 and the reflection sheet 12. For this reason, light does not concentrate in one place, and light leakage can be suppressed.

  As a result, light entering from the lower side of the light guide plate 13 other than the top flat surface 31 of the light coupling member 30 can be reduced, and light leakage of the backlight 10 can be made inconspicuous. With such a backlight 10, when applied to the backlight of the liquid crystal display device 1, luminance unevenness due to stray light is not generated on the surface of the liquid crystal display device 1, thereby causing a problem.

  When the LED chip 23 a is shifted to the end side (left side in FIG. 1) of the optical coupling member 30, it may be emitted from the end of the optical coupling member 30 to the outside of the optical coupling member 30. However, the light guide plate 13 does not exist in the direction of the light, and the frame is not shown. Therefore, even if light emitted from the end of the optical coupling member 30 to the outside of the optical coupling member 30 exists, luminance unevenness due to stray light is not generated on the surface of the liquid crystal display device 1 to cause a problem.

  Here, since the optical coupling member 30 is formed by molding a resin with a mold or the like, it is preferable that the optical coupling member 30 has a shape that is easy to mold, such as symmetrical, considering the flow of the resin in the mold.

  Since the curved surface 32a side needs to be finished to a mirror surface, it is required that the surface accuracy of the portion of the mold corresponding to that portion is also high. However, in the case of a mold for molding the optical coupling member 30 of the backlight 10 of the present embodiment, the mold portion corresponding to the curved surface 32b can be created with low surface accuracy, and therefore there are few mirror-finished portions of the mold. Become. As a result, there is an advantage that the mold is inexpensive.

(Application to liquid crystal display devices)
As described above, the light source unit 20 of the present embodiment can be applied to the liquid crystal display device 1 as shown in FIGS. In this case, the light source units 20 shown in FIG. 2 are arranged and used in the X direction. As a result, the light guide plate 13 is also configured with large dimensions in both the X direction and the Y direction. By adopting such a configuration, the area of the light guide plate 13 is increased corresponding to the increase in the area of the liquid crystal panel 4 of the liquid crystal display device, and a backlight suitable for practical use of the large-screen liquid crystal display device 1 is realized. can do.

  For example, eight heat sinks having a length of 110 mm, a width of 100 mm, and a thickness of 2 mm are used, and a set of eight heat sinks 22, an optical coupling member 30, and an LED substrate 24 a is arranged on the large heat guide 22. It is possible to configure a backlight type liquid crystal display device 1 that configures a light source module that fixes the light plate 13 and illuminates the liquid crystal panel 4 from the back.

  12A and 12B exemplify the case where the size of the liquid crystal panel 4 is 60 type, for example, the size is different from 60 type, such as 70 type which is a size of 60 type or more. Also good.

  In the present embodiment, the backlight 10 is applied to the liquid crystal display device 1. However, the present invention is not necessarily limited thereto, and for example, the backlight 10 can be applied to a lighting device. That is, the backlight 10 of the present embodiment can be applied to a large planar light source as it is. Further, since no member is required around the light guide plate 13, it can be applied to a larger planar light source by arranging them seamlessly.

  As described above, the backlight 10 according to the present embodiment includes the LED chip 23 a, the light guide plate 13, and the light coupling member 30 that guides light from the LED chip 23 a to the light guide plate 13. The optical coupling member 30 includes a top flat surface 31 that allows light to enter the light guide plate 13 side, two side surfaces located on both sides of the top flat surface 31, and a light incident portion that receives light from the LED chip 23a. And a light incident surface 33a. One surface of the two side surfaces is a reflecting surface that reflects light from the light incident surface 33 a located below the curved surface 32 a and guides it to the top flat surface 31. On the other hand, at least a part of the surface of the other side surface portion 36 which is the other of the two side surface portions including the boundary with the top flat surface 31 is formed to be rougher than the reflecting surface made of the curved surface 32a.

  According to said structure, the light radiate | emitted from LED chip 23a below the light-guide plate 13 injects into the optical coupling member 30 from the light-incidence surface 33a, reflects on the curved surface 32a of the optical coupling member 30, and is a top part. The light enters the light guide plate 13 from the flat surface 31. While the light incident on the light guide plate 13 is totally reflected inside the light guide plate 13, a part of the light propagates to the end of the light guide plate 13. Is broken and emitted from the upper surface of the light guide plate 13.

  As a result, unlike the conventional side edge type light guide plate, since it is a backlight directly under the light guide plate, a light source and a light guide plate for avoiding thermal expansion required in the side edge type light guide plate, The gap between the LED chip 23a and the light guide plate 13 can be increased, and the light utilization efficiency can be improved.

  In the present embodiment, since the light coupling member separate from the light guide plate is provided so that light is incident from the incident portion on the lower surface of the light guide plate, the incident light is guided while being totally reflected inside the light guide plate. Lighted. As a result, it is not necessary to process the light guide plate, the coupling efficiency from the light source to the light guide plate can be increased, the light utilization efficiency can be improved, and the manufacturing cost is also reduced.

  By the way, in the backlight 10 having such a structure, when the positional relationship between the light coupling member 30 and the LED chip 23a deviates from a predetermined position, the LED chip 23a is more specifically moved from the predetermined position with respect to the light coupling member 30. If the second side surface portion 36 is also displaced, a part of the light reflected on the reflecting surface made of the curved surface 32a is not coupled to the top flat surface 31 of the optical coupling member 30, and is opposite to the reflecting surface made of the curved surface 32a. It becomes stray light emitted from the surface of the other side surface 36 of the other of the two side surfaces. The amount of stray light generated increases as the stray light shifts farther toward the other side surface 36 than the predetermined position with respect to the optical coupling member 30. When such stray light enters the light guide plate 13, uneven brightness occurs in the light guide plate 13.

  Therefore, in the present embodiment, at least a part of the surface of the other side surface portion 36 that is the other surface of the two side surface portions of the optical coupling member 30 including the boundary with the top flat surface 31 is a curved surface 32a. It is formed rougher than the reflecting surface. As a result, the light reaching the surface of the other side surface portion 36 causes irregular reflection on the rough surface, and therefore does not enter the light guide plate 13.

  Therefore, the backlight 10 that can increase the coupling efficiency from the LED chip 23 a to the light guide plate 13 and reduce the luminance unevenness of the light guide plate 13 without processing the light guide plate 13 can be provided.

  In the present embodiment, the optical coupling member 30 has a cross-sectional arch shape or semicircular shape. However, in the present invention, the shape of the optical coupling member 30 is not necessarily limited to this. That is, since the other side surface portion 36 does not have a function as a reflecting surface, the shape can be freely adopted in principle. For this reason, the other side surface portion 36 can be extended to the lower surface to have a function as a leg portion for the installation surface of the optical coupling member 30. Thereby, the optical coupling member 30 can be stably arranged on the installation surface.

  Moreover, in the backlight 10 of this Embodiment, at least one part including the boundary with the top flat surface 31 in the other surface of the two side parts in the optical coupling member 30, ie, the curved surface of the other side part 36 The surface 32b has a surface roughness Ra ≧ 0.2. As a result, the light reaching the surface of the other side surface portion 36 is surely irregularly reflected on the rough surface, so that it does not enter the light guide plate 13.

  Moreover, in the backlight 10 of this Embodiment, the reflective surface which is one surface of the two side parts in the optical coupling member 30 is surface roughness Ra <0.2. Accordingly, the curved surface 32 a of the optical coupling member 30 is surely totally reflected and is incident on the light guide plate 13 from the top flat surface 31 of the optical coupling member 30.

  Moreover, in the backlight 10 of this Embodiment, the optical coupling member 30 is cross-sectional arch shape or semicircle shape. Accordingly, it is possible to reflect most of the light incident from the LED chip 23 a located below the optical coupling member 30 through the light incident surface 33 a by the curved surface and guide it to the top flat surface 31. Moreover, in the optical coupling member 30 having a cross-sectional arch shape or a semicircular shape, since the outer shape is symmetrical, there is an advantage that a mold can be easily formed.

  Further, the liquid crystal display device 1 of the present embodiment includes the light source module of the present embodiment as a backlight. Therefore, the liquid crystal display device 1 including the backlight 10 capable of increasing the coupling efficiency from the LED chip 23a to the light guide plate 13 and reducing the luminance unevenness of the light guide plate 13 without processing the light guide plate 13 is provided. be able to.

  Note that the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in the present embodiment. Embodiments are also included in the technical scope of the present invention.

  The present invention can be used for a backlight of a liquid crystal display device such as a television or a monitor, and is particularly applicable to a backlight directly under the light source. The backlight can be applied to a lighting device as a large planar light source.

1 Liquid crystal display device 10 Backlight (light source module)
13 Light guide plate 20 Light source unit 23a LED chip (light source)
24a LED board (light source board)
30 optical coupling member 31 top flat surface (top flat portion)
32a Curved surface 32b Curved surface 33a Light incident surface (light incident portion)
36 The other side

Claims (5)

A light source module comprising a light source, a light guide plate, and an optical coupling member that guides light from the light source to the light guide plate,
The optical coupling member is
And having a top flat part for entering light on the light guide plate side, two side parts located on both sides of the top flat part, and a light entrance part for receiving light from the light source,
One surface of the two side surface portions is a reflection surface that reflects light from a light incident portion located below the curved surface and guides it to the top flat portion. The other surface of the light source module is characterized in that at least a part including a boundary with the top flat portion is formed to be rougher than the reflecting surface.   2. The surface roughness Ra ≧ 0.2 of at least a part including a boundary with the top flat portion on the other surface of the two side surface portions of the optical coupling member. The light source module described.   3. The light source module according to claim 1, wherein a reflection surface which is one surface of two side surfaces of the optical coupling member has a surface roughness Ra <0.2.   4. The light source module according to claim 1, wherein the optical coupling member has an arch shape or a semicircular shape in cross section.   A liquid crystal display device comprising the light source module according to claim 1 as a backlight.