JP2012216428A - Light source module, and electronic device equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source module capable of enhancing coupling efficiency from a light source to a light guide plate without effecting processing of the light guide plate and improving light utilization efficiency and moreover suppressing luminance unevenness.SOLUTION: The light source module is provided with a planar light guide plate 13, LED chips 25a, 25b arranged in a lower part of the light guide plate 13, and a light coupling member 30 arranged between the light guide plate 13 and the LED chips 25a, 25b. The light coupling member 30 includes a top part flat face 31 in surface-contact with the light guide plate 13 in parallel and a hung-down curved face 32 reflecting the light from the LED chips 25a, 25b and guiding it to the top part flat face 31. The light source module is further provided with prisms 35a, 35b, arranged on the same face with the LED chips 25a, 25b, which reflect toward the top part flat face 31 the light returned to the light coupling member 30 without performing light-coupling to the light guide plate 13.

Description

  The present invention relates to a light source module and an electronic apparatus including the light source module.

  In recent years, in order to reduce the thickness of a liquid crystal display device, a backlight having a side edge (also referred to as “sidelight”) type light guide plate that emits light from a light source in a planar shape by the light guide plate has been widely used. Yes.

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

  However, in the side edge type light guide plate, the light guide plate expands and contracts due to thermal expansion, and 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 light guide plate, the greater the amount of expansion and contraction, and the greater the gap between the light source and the light guide plate.

  In order to solve this problem, for example, display device backlights disclosed in Patent Documents 1 and 2 have been proposed.

  As shown in FIG. 19, in the backlight 100 of Patent Document 1, a light emitting diode 101 is provided below the light guide plate 110. Then, immediately above the light emitting diode 101 on the surface of the light guide plate 110, in order to reflect the light from the light emitting diode 101 toward the both end sides of the light guide plate 101, curved reflecting surfaces 111 and 111 are formed. 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 101 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, almost all of the light emitted from the light emitting diode 101 is introduced into the light guide plate 110, so that the side edge ("side light" It is also possible to improve the light coupling efficiency and the light utilization efficiency of the light to the light guide plate 110 than the type light guide plate.

  As shown in FIG. 20, in the backlight 200 of Patent Document 2, a light receiving / reflecting portion 211 having a light receiving surface 211 a and a reflecting surface 211 b is formed at one end of the light guide plate 210. Further, the LED 201 that is a light source is disposed directly below the light receiving / reflecting portion 211 in the light guide plate 210.

JP 2006-49324 A (published February 16, 2006) JP 2004-319164 A (published on November 11, 2004) Japanese Patent Laying-Open No. 2008-257721 (released on October 23, 2008) JP 2009-193669 A (published August 27, 2009)

  However, the backlights of Patent Documents 1 and 2 have the following problems.

  First, in the backlight 100 for a display device disclosed in Patent Document 1, it is necessary to form reflective surfaces 111 and 111 having curved surfaces on the light guide plate 110. Therefore, since the light guide plate 110 has to be processed, the cost increases, and in particular, the processing of the large light guide plate has a problem that the area is large and difficult.

  In addition, since the light is totally reflected by the reflection surfaces 111 and 111, the light is not transmitted at all directly above the light emitting diode 101 on the surface of the light guide plate 110, and becomes a dark portion, resulting in uneven brightness. Even if the reflective surfaces 111 and 111 are configured to reflect only a part and transmit the remaining part, unless the reflectance is controlled with extremely high accuracy, dark portions or bright portions are generated and uneven brightness occurs. To do.

  Further, the backlight 100 for a display device disclosed in Patent Document 1 has a disadvantage that the cost is higher than that of a simple flat light guide plate because the light guide plate needs to be processed. 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, the backlight 200 of Patent Document 2 is configured such that light is incident from a light receiving / reflecting portion 211 formed only at one end of the side portion of the light guide plate 210. For this reason, LED201 cannot be arrange | positioned in the center of the light-guide plate 210. FIG. Therefore, particularly in a large TV that requires a large light guide plate, there is a problem that the light intensity at the center of the light guide plate 210 is reduced.

  Further, when attention is paid to the manufacturing method of the backlight 200, there is a problem that the cost is increased due to the processing of the light receiving / reflecting portion 211.

  First, when the light receiving reflection part 211 is formed by processing a part of the shape of the light guide plate 210, there is a problem that the processing of the light guide plate 210 is costly. In addition, it is necessary to increase the thickness of the light guide plate 210 to the extent that it can withstand the processing of the light receiving / reflecting portion 211.

  Further, when the light receiving / reflecting part 211 is formed of a separate member from the light guide plate 210 and bonded to the light guide plate 210, the light receiving / reflecting part 211 needs to be bonded to the side surface of the light guide plate 210 having a thickness of several millimeters. It is difficult to. Therefore, there is a problem that it takes cost to bond the side surface of the light guide plate 210 to the light receiving / reflecting portion 211.

  The present invention has been made in view of the above-described conventional problems, and the object thereof is to increase the coupling efficiency from the light source to the light guide plate without improving the light guide plate, to improve the light utilization efficiency, and An object of the present invention is to provide a light source module capable of suppressing luminance unevenness and achieving cost reduction, and an electronic device including the same.

  In order to solve the above problems, a light source module according to the present invention includes a flat light guide plate, a light source disposed below the light guide plate, and an optical coupling disposed between the light guide plate and the light source. The light coupling member has a top flat surface that abuts on a surface parallel to the light guide plate, and a reflection surface that reflects light from a light source and guides the light to the top flat surface. It is characterized by further comprising a first reflecting member provided on the same surface as the light source, which reflects light returning to the optical coupling member without optical coupling toward the flat top surface.

  In the light source module of the present invention, a light source is provided below the flat light guide plate, and an optical coupling member that couples light emitted from the light source to the light guide plate is provided between the light guide plate and the light source. For this reason, the light emitted from the light source below the light guide plate is optically coupled to the light guide plate via the optical coupling member.

  According to said structure, since the said optical coupling member has the top flat surface which contact | abuts in the surface parallel to the said light-guide plate, and the reflective surface which reflects the light from a light source and guides it to the said top flat surface, The emitted light enters the optical coupling member and is reflected by the reflecting surface. Then, the light reflected by the reflecting surface is guided to the top flat surface and is incident on the lower surface of the light guide plate in an oblique direction. The light incident on the light guide plate in an oblique direction moves to the end of the light guide plate while totally reflecting the inside of the light guide plate, and the total reflection condition is broken by the optical path conversion element on the way, and is emitted to the outside.

  Therefore, according to the above configuration, unlike the conventional side edge type light guide plate, the backlight is a type directly under the light guide plate, so that the thermal expansion required in the side edge type light guide plate is avoided. Therefore, a gap between the light source and the light guide plate is not necessary. Therefore, according to said structure, the emitted light from a light source can be prevented from leaking directly outside, and the coupling efficiency from a light source to a light-guide plate can be improved.

  Further, in the above configuration, by providing a light coupling member separate from the light guide plate, light is incident on the flat light guide plate at an angle, so that incident light is totally reflected inside the light guide plate. Light is guided.

  As a result, incident light from the light source via the optical coupling member can be guided inside the light guide plate without processing 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 improve the light use efficiency without processing the light guide plate.

  Further, according to the above configuration, the first reflecting member causes light (stray light) that has not been optically coupled to the light guide plate and returned to the optical coupling member to the top flat surface on the same plane as the light source. Reflect toward you. Thereby, even in a state where the optical path is shifted due to the positional shift between the light source and the optical coupling member, stray light can be reduced and a decrease in the optical coupling rate can be prevented. As a result, luminance unevenness can be suppressed.

  Patent Documents 1 to 4 do not describe providing the first reflecting member in the present invention at all. That is, in Patent Documents 1 to 4, light that is not optically coupled to the light guide plate and returned to the optical coupling unit cannot be rereflected so as to be optically coupled to the light guide plate again.

  In the light source module of the present invention, the first reflecting member has a re-reflecting surface, and the light reflected by the re-reflecting surface and optically coupled to the light guide plate does not return to the optical coupling member and is guided to the light source module. It preferably crosses light that is optically coupled to the optical plate.

  According to the above configuration, the direction of the light reflected by the re-reflecting surface and optically coupled (incident) to the light guide plate is the optical coupling member with respect to the vertical or horizontal center line of the light guide plate. The direction of light that is optically coupled (incident) to the light guide plate is not reversed and is directed in the opposite direction. Thereby, light can be irradiated to the wide range of the said light-guide plate.

  In the light source module of the present invention, it is preferable that the first reflecting member reflects light reflected by the reflecting surface in a direction opposite to the light guide plate toward the top flat surface.

  According to said structure, when the said optical coupling member is reduced in size and the light which is not optically coupled to the said light-guide plate increases, ie, when stray light increases, the said light is reflected toward the said top flat surface. As a result, luminance unevenness can be suppressed.

  In the light source module of the present invention, the re-reflecting surface may be a mirror surface or a surface on which a metal film is formed.

  The re-reflecting surface is preferably a surface capable of total reflection. However, depending on the angle between the stray light and the re-reflecting surface, a mirror surface, a surface on which a metal film is formed, or the like can be used properly.

  In the light source module of the present invention, it is preferable that all of the light emitted from the light source strikes the reflecting surface at least once.

  The light source emits light at a predetermined radiation angle. When a part of the light radiated at such a radiation angle is incident on the light guide plate without being reflected by the reflection surface of the optical coupling member, there is a possibility that light is leaked without being reflected inside the light guide plate. According to said structure, since all the light radiated | emitted from the said light source strikes the said reflective surface at least once, the said light leakage can be avoided and optical coupling efficiency can be improved more. it can.

  In the light source module of the present invention, the reflection surface is a curved surface formed by hanging from the top flat surface, and the light emitted from the light source is condensed on the top flat surface. preferable.

  “Condensate” here means that the light is focused (with the light beam diameter gradually becoming smaller) and guided to the top flat surface.

  According to the above configuration, the reflection surface is a curved surface formed by hanging from the top flat surface, and the light emitted from the light source is collected on the top flat surface and enters the light guide plate. The optical coupling efficiency can be further improved.

  In the light source module of the present invention, the reflecting surface is a parabolic surface having a parabolic cross section, and a focal position of the parabolic surface is closer to a central portion of the optical coupling member than the light source. preferable.

  The term “paraboloid” as used herein means a surface having a parabola having the same cross-sectional shape in a specific direction. For example, when the optical coupling member is provided on a vertical or horizontal center line of the light guide plate, a surface in which a cross-sectional shape perpendicular to the direction of the center line is the same parabola in the direction of the center line It is.

  According to said structure, the said reflective surface is a parabolic surface where a cross section becomes a parabola, and the focal position of the said parabolic surface is near the center part of the said optical coupling member rather than the said light source. That is, since the light source exists on the end side of the focal position of the paraboloid, the light emitted from the light source can be totally reflected by the reflecting surface, and the light can efficiently reach the top flat surface. Is possible. As a result, light emitted from the light source can be efficiently optically coupled to the light guide plate.

  In the light source module of the present invention, the reflection surface is an ellipsoid whose section is an ellipse, and one focal position of the ellipse is closer to the center of the optical coupling member than the light source, Is preferably located on the lower surface of the light guide plate.

  The term “elliptical surface” as used herein means a surface that forms an arc of an ellipse having the same cross-sectional shape in a specific direction. For example, when the optical coupling member is provided on the vertical or horizontal center line of the light guide plate, the cross-sectional shape perpendicular to the direction of the center line is the same elliptical arc in the direction of the center line. It is a surface.

  According to the above configuration, the reflecting surface is an ellipsoid whose section is an ellipse, and one focal position of the ellipsoid is closer to the center of the optical coupling member than the light source (that is, The light source exists on the end side of the focal position of the elliptical surface), and the other focal position exists on the lower surface of the light guide plate. Thereby, the light radiated | emitted from a light source can be totally reflected by a reflective surface. Therefore, the light emitted from the light source can be efficiently optically coupled to the light guide plate. In addition, the elliptical surface can be optically coupled to the light guide plate by focusing light more than the parabolic surface.

  In the light source module of the present invention, it is preferable that the light source is composed of a plurality of LEDs, and the reflection surface reflects light emitted from each LED and guides it to the top flat surface.

  According to the above configuration, since the LED has a small shape and a high illuminance, it is suitable as a light source for the light source module.

  In the light source module of the present invention, the top flat surface of the optical coupling member is provided on a vertical or horizontal center line of the light guide plate, and the reflection surface is symmetrical with respect to the center line. Preferably, the LEDs are provided in two rows so as to correspond to the reflecting surface.

  According to said structure, the said top flat surface in the said optical coupling member is provided on the centerline of the vertical or horizontal direction in the said light-guide plate, and the said reflective surface is symmetrical with respect to the said centerline. Since the LEDs are provided in two rows so as to correspond to the reflecting surface, the luminance on the vertical or horizontal center line of the light guide plate is the highest. For example, the screen becomes easier to see when the luminance on the vertical or horizontal center line of the liquid crystal panel is increased. In this regard, for example, when the light source module of the present invention is incorporated in a liquid crystal display device, it is possible to provide a liquid crystal display device suitable for the luminance distribution.

  In the light source module of the present invention, in the direction perpendicular to both the direction of the center line and the thickness direction of the light guide plate, the width of the top flat surface is equal to that of the lower surface of the light guide plate irradiated with light from the LED. The width is preferably the same as the width of the light irradiation region.

  According to the above configuration, in the direction perpendicular to both the center line direction and the thickness direction of the light guide plate, the width of the top flat surface is equal to that of the lower surface of the light guide plate irradiated by the light from the LEDs. Since it is the same as the width of the light irradiation region, the light emitted from the LEDs arranged in two rows can be efficiently optically coupled to the light guide plate.

  In the light source module of the present invention, the optical coupling member has two reflection surfaces, and the two reflection surfaces constitute a V-shaped surface extending along a vertical or horizontal center line of the light guide plate. The top flat surface is connected to two reflecting surfaces and is formed so as to be symmetric with respect to the center line. The LED emits light of the V-shaped surface. It is preferable that they are arranged in a line so as to be branched.

  According to the above configuration, the light emitted from the LED has its optical path branched in two directions on the V-shaped surface formed by the two reflecting surfaces. Then, the light branched into the optical paths in the two directions is respectively connected to the two reflecting surfaces and guided to the two top flat surfaces formed so as to be symmetric with respect to the center line. Will be combined.

  Therefore, unlike the conventional side edge type light guide plate, the backlight is directly under the light guide plate. Therefore, a light source and a light guide plate for avoiding thermal expansion required in the side edge type light guide plate are provided. No gap is required. Therefore, according to said structure, the emitted light from a light source can be prevented from leaking directly outside, and the coupling efficiency from a light source to a light-guide plate can be improved. Further, incident light from the light source via the optical coupling member can be guided inside the light guide plate without processing the light guide plate.

  Furthermore, according to the above configuration, the emitted light from the LEDs arranged in a row is branched into two optical paths on the V-shaped surface, so that the arrangement of the LEDs becomes simple and the labor required for mounting the LEDs can be reduced. There is an advantage.

  In order to solve the above problems, an electronic apparatus according to the present invention includes the above-described light source module.

  Accordingly, it is possible to provide an electronic device that can increase the coupling efficiency from the light source to the light guide plate, improve the light utilization efficiency, and suppress luminance unevenness without processing the light guide plate.

  As described above, the light source module of the present invention includes a flat light guide plate, a light source disposed below the light guide plate, and an optical coupling member disposed between the light guide plate and the light source. The optical coupling member has a top flat surface that abuts on a plane parallel to the light guide plate, and a reflective surface that reflects light from the light source and guides the light to the top flat surface, and does not optically couple to the light guide plate. The light reflecting member is further provided with a first reflecting member provided on the same surface as the light source for reflecting the light returning to the light coupling member toward the top flat surface.

  Moreover, the electronic device of this invention is the structure provided with the said light source module as mentioned above.

  Therefore, it is possible to increase the coupling efficiency from the light source to the light guide plate, improve the light use efficiency, and suppress luminance unevenness without processing the light guide plate.

It is sectional drawing which shows one Embodiment of the liquid crystal display device in this invention. It is a disassembled perspective view which shows the structure of the said liquid crystal display device. It is a perspective view which shows the structure of the light source module main body in the said liquid crystal display device. It is a perspective view which shows the structure of the backlight in the said liquid crystal display device. (A) is sectional drawing which shows the optical path when the light radiate | emitted from LED 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 vicinity. is there. (A) is sectional drawing which shows the optical path when the light radiate | emitted from LED injects into a light-guide plate via the optical coupling member which has an elliptical surface, (b) is principal part sectional drawing which shows the LED vicinity. (B) is principal part sectional drawing which shows the top flat surface vicinity. FIG. 6B shows the positional relationship between the LED and the focal point of the hanging curved surface in the configuration of FIG. 6B, and FIG. 6A is a cross-sectional view showing the optical path when the light emitting point of the LED is on the end side of the focal point; (B) is sectional drawing which showed the optical path when the light emission point of LED corresponds with a focus, (c) is the cross section which showed the optical path when the light emission point of LED exists in the center part side rather than a focus. (D) is sectional drawing which shows the case where the edge part of the center part side in LED exists in an edge part side rather than a focus, (e) is the edge part of the center part side in LED from a focus. It is sectional drawing which shows the case where also exists in the center part side. (A) is sectional drawing which showed typically the relationship between the width | variety of a top flat surface, and the width | variety of the light irradiation area | region irradiated to the light-guide plate lower surface, (b) is the width | variety of the top flat surface irradiated with light. The case where it is smaller than the width | variety of an area | region is shown, (c) shows the case where the width | variety of a top flat surface is larger than the width | variety of a light irradiation area | region. It is sectional drawing which shows an optical path when the light radiate | emitted from two LED injects into a light-guide plate through the optical coupling member which has a paraboloid and an ellipsoid. (A) is a front view which shows an example of a structure of a liquid crystal display device, (b) is the side view. (A) is a front view which shows the other example of a structure of a liquid crystal display device, (b) is the side view. (A) is sectional drawing which shows the structure of a liquid crystal display device, (b) is a graph which shows the luminance distribution of the height direction of a light-guide plate. It is principal part sectional drawing which shows the structure of the edge part of the said liquid crystal display device. It is a perspective view which shows the structure of the backlight in the said liquid crystal display device. It is a perspective view which shows the structure of the backlight in the said liquid crystal display device. It is a graph which shows the relationship between the positional offset amount of LED and the optical coupling member, and coupling efficiency. (A) shows the structure of the modification of a light source module, Comprising: It is sectional drawing which shows the optical path when the light radiate | emitted from one LED injects into a light-guide plate through the optical coupling member which has a paraboloid. FIG. 6B is a cross-sectional view showing a configuration of a modified example of the light source module and showing an optical path when light emitted from one LED enters the light guide plate through an optical coupling member having an elliptical surface. It is. It is sectional drawing which shows the structure of the other modification of a light source module. FIG. 11 is a cross-sectional view illustrating a configuration of a backlight of a liquid crystal display device of Patent Document 1. It is a perspective view which shows the structure of the backlight of patent document 2. FIG.

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

  As shown in FIG. 2, the liquid crystal display device (electronic device) 1 according to the present embodiment includes a backlight 10, a diffusion sheet 2, a prism sheet 3, a liquid crystal panel 4, and a bezel 5 in order from the bottom. .

The backlight 10 includes a light source module 20, a chassis 11 having a single opening, a reflection sheet 12 (second reflection member), and a light guide plate 13 in order from the bottom. The chassis 11 is composed of 11a and 11b which are divided into two portions where a light coupling member (not shown) abuts against the light guide plate 13. Similarly to the chassis 11, the reflection sheet 12 is also divided into two portions where a light coupling member (not shown) abuts against the light guide plate 13, and is configured by reflection sheets 12 a and 12 b. A slit 14 is formed between the chassis 11a and 11b and the reflection sheets 12a and 12b. The slit 14 is divided into a plurality of portions near the position where the optical coupling member 30 contacts the light guide plate 13. Further, as shown in FIGS. 1 and 3, the light source module 20 is provided with a sheet-like heat sink 22 on a light source holder 21 formed in a strip shape, and on the heat sink 22,
LED (Light Emitting Diode) substrates 24a and 24b are provided, and LED chips 25a and 25b as light sources are arranged on the LED substrates 24a and 24b. Since the LED chips 25a and 25b have a very fine size, description thereof is omitted in FIG. 3 for the purpose of preventing complexity of the drawing. In this embodiment, the LED chips 25a and 25b are used as the 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 is used. It is also possible. The chassis 11 and the light source holder 21 may be integrally formed by molding a plate-like member or the like.

  The optical coupling member 30 is provided on the LED chips 25a and 25b. That is, the LED chips 25a and 25b are arranged on the LED substrates 24a and 24b, and the optical coupling member 30 is disposed on the LED chips 25a and 25b. In order to prevent the LED chip from being damaged, it is preferable to provide spacers 23a and 23b.

  That is, the liquid crystal display device 1 of the present embodiment includes a liquid crystal panel 4, a light guide plate 13 that emits light to the liquid crystal panel 4, and an optical element that couples light to the light guide plate 13, as shown in FIG. The light coupling member 30, the LED chips (light sources) 25 a and 25 b that emit incident light to the light coupling member 30, and the light returned to the light coupling member 30 without being optically coupled to the light guide plate 13 are directed toward the top flat surface 31. The liquid crystal panel 4, the light guide plate 13, the optical coupling member 30, and the LED chips 25a and 25b are arranged in this order. The prisms 35a and 35b are provided on substantially the same plane as the LED chips 25a and 25b. Therefore, the backlight 10 in the liquid crystal display device 1 according to the present embodiment is a backlight 10 directly under the light source in which the LED chips 25 a and 25 b are provided below the light guide plate 13.

  As shown in FIG. 1, a light source module 20 is provided as a protruding portion on the back side of the liquid crystal display device, and a light coupling member 30 and LED chips 25a and 25b are housed therein. Yes. Further, the light source module 20 is formed in a strip shape in the longitudinal direction of the liquid crystal display device 1, and the optical coupling member 30 housed therein is also strip-shaped in the longitudinal direction of the liquid crystal display device 1 (the depth direction in FIG. 1). Is formed. That is, it can be said that the “protrusion” is composed of an optical coupling member, a light source, a cover thereof, and the like among members constituting the light source module 20 of the liquid crystal panel described later.

  In the present embodiment, the projecting portion (light source module 20) is formed in a rectangular cross section projecting from the flat surface of the chassis 11, but is not limited thereto, and the cross section is semicircular or semielliptical. It may be a polygon other than a quadrangle such as a triangle. In other words, in the present invention, the protruding portion is not intended to be a convex shape having a square cross section, and various shapes and sizes are allowed as long as it has a function capable of storing an optical coupling member, a light source, and the like. The

  In this specification, “the prisms 35a and 35b (first reflecting member) provided on the same surface as the LED chips 25a and 25b (light source)” means that the prisms 35a and 35b are provided on the same surface as the LED chips 25a and 25b. This means that the prisms 35a and 35b are provided on the extended line of the surface on which the LED chips 25a and 25b are arranged.

  Here, in the present embodiment, as shown in FIG. 4, the optical coupling member 30 is formed of a belt having a substantially cross-sectionally shaped cross section provided between the light guide plate 13 and the light source 25 including the LED chips 25 a and 25 b. In addition, the material of the optical coupling member 30 is made of the same resin as the material of the light guide plate 13. Specifically, the surface of the optical coupling member 30 on the light guide plate 13 side is a top flat surface 31 that contacts the flat light guide plate 13, and a hanging curved surface (reflective surface) that hangs down from the top flat surface 31 to both ends. It consists of 32 and 32 (32a and 32b). The light guide plate 13 and the optical coupling member 30 are separate members, and air is not interposed between them. Specifically, both members are joined by an adhesive or laser welding.

  According to the backlight 10, for example, the light emitted from the LED chip 25 a is reflected by the hanging curved surface 32 of the optical coupling member 30, and the reflected light reaches the top flat surface 31 of the optical coupling member 30 to change the arrival direction. The light enters the light guide plate 13 while being maintained. As shown in FIG. 5A, the reflection sheet 12 is provided on the lower surface of the light guide plate 13. For this reason, the light incident on the light guide plate 13 travels by being totally reflected inside the right side of the light guide plate 13 shown in FIG. 4, FIG. 5A, etc., and collides with a light scatterer which is not shown. As a result, the traveling angle in the light guide plate 13 is changed, the total reflection condition is broken, the light 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 2 and the prism sheet 3. Note that the light emitted from the LED chip 25b also proceeds symmetrically with the light from the LED chip 25a, as shown in FIG.

  As described above, according to the backlight 10, the amount of expansion and contraction in the thickness direction of the optical coupling member 30 is not large. Therefore, it is necessary to provide a clearance between the LED chip 25 and the optical coupling member 30 in consideration of the expansion and contraction amount. Absent. Further, when light emitted from the LED chip 25 enters the optical coupling member 30, it is reflected by the drooping curved surface 32 and enters the light guide plate 13 through the top flat surface 31. Since the material of the optical coupling member 30 is made of the same resin as that of the light guide plate 13, the emitted light from the LED chip 25 passes through the top flat surface 31 and enters the light guide plate 13 without loss of light. Therefore, the light emitted from the LED chip 25 can be prevented from leaking directly to the outside, and the optical coupling efficiency can be improved.

  Moreover, according to the backlight 10, the light guide plate 13 and the light coupling member 30 are separate members, and the light coupling member 30 is bonded to the flat light guide plate 13 that is normally used. For this reason, the process to the light-guide plate 13 which is the technical idea currently disclosed by patent document 1 becomes unnecessary, and cost reduction can be implement | achieved.

  Further, in the backlight 10 of the present embodiment, the light emitted from the LED chip 25 is emitted in the vertical direction with respect to the light guide plate 13 and is incident on the optical coupling member 30. Then, the light is reflected by the drooping curved surface 32 on the side surface of the optical coupling member 30, and the direction of the optical path is changed from the vertical direction (relative to the light guide plate 13) to the oblique direction (relative to the light guide plate 13). The light is coupled to the light guide plate 13 through the surface 31.

  On the other hand, as a technique for introducing light from the light source into the light guide plate in an oblique direction with respect to the light guide plate via the optical coupling member and optically coupling with the light guide plate, the technology disclosed in Patent Document 3 and Patent Document 4 is disclosed. Technology is known. In the technologies disclosed in both publications, the light source (LED) is disposed obliquely with respect to the light guide plate. That is, the light emission direction from the light source is oblique to the light guide plate. In the said patent document 4, the base for hold | maintaining a light source diagonally is disclosed.

  However, it is generally difficult to dispose the LEDs obliquely so as to enter the light guide plate in an oblique direction as in the techniques disclosed in Patent Document 3 and Patent Document 4. For example, in order to arrange the LEDs diagonally, it is necessary to mount a pedestal (for example, a pedestal disclosed in Patent Document 4) for holding the LED diagonally on the chassis, and then mount the LED on the pedestal from an oblique direction. There is. For this reason, the techniques disclosed in Patent Document 3 and Patent Document 4 make it difficult to assemble the backlight and cannot be put to practical use.

  On the other hand, in the backlight 10, the LED chip 25 is arranged so that the emitted light radiates in a direction perpendicular to the light guide plate 13. That is, unlike the techniques described in Patent Documents 3 and 4, there is no need to dispose the LEDs obliquely so as to enter the oblique direction with respect to the light guide plate, and the LED chip 25 is perpendicular to the flat chassis 11. And it is only mounted from directly above. Therefore, in the backlight 10 of the present embodiment, the assembling method and structure can be simplified. As described above, the backlight 10 of the present embodiment has an advantage that the LED chip 25 can be mounted vertically in terms of the structure in comparison with the techniques of Patent Documents 3 and 4.

  Moreover, the shape of the said hanging curved surfaces 32 and 32 should just have the function to totally reflect the emitted light from LED chip 25. FIG. For example, as shown in FIG. 5A, the shape of the drooping curved surfaces 32 and 32 may be a parabola in a cross section (a shape that becomes a parabola in a cross section perpendicular to the direction in which the optical coupling member 30 that is a belt-like body extends). . However, the present invention is not necessarily limited to this, and as shown in FIGS. 6A to 6C, a cross-sectional ellipse (a shape that forms an elliptical arc in a cross section perpendicular to the extending direction of the optical coupling member 30 that is a belt-like body). It is also possible. Further, 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 a lower flat surface 33. 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 the recess 34 may not be present. That is, in this embodiment, it is only necessary to secure an optical path to the light guide plate 13 for the light reflected by the hanging curved surfaces 32 and 32, and therefore, a portion that does not become an optical path (portion where light does not pass) 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, irradiation from the light guide plate 13 to the liquid crystal panel 4 on the top flat surface 31 can be improved.

In addition, LED chips 25a and 25b are provided close to each other below the lower flat surfaces 33 and 33 of the optical coupling member 30, respectively. When the hanging curved surface 32 is formed of a parabolic section, the LED chips 25a and 25b (end portions on the center side (the top flat surface 31 side)) are suspended curved surfaces formed of a parabolic section as shown in FIG. is preferably present on the end side than the 32, 32 position of the focal point f ₁ of. Thereby, the light radiated from the LED chips 25a and 25b can be totally reflected by the hanging curved surface 32, and the light can efficiently reach the top flat surface 31. As a result, the light emitted from the LED chips 25a and 25b can be efficiently optically coupled to the light guide plate 13, and the optical coupling efficiency can be improved as compared with the side edge type configuration.

When the hanging curved surface 32 has an elliptical cross section, as shown in FIGS. 6B and 7, the LED chips 25 a and 25 b (ends on the center side (top flat surface 31 side)) have an elliptical cross section. it is preferably present on the end side than the position of one focus f ₂ in drooping curved surface 32, 32 of. Furthermore, in this case, as shown in FIG. 6C, it is preferable that the other focal point f ₃ of the hanging curved surfaces 32 and 32 coincides with the lower surface of the light guide plate 13. Thereby, the light radiated | emitted from LED chip 25a * 25b can be totally reflected by the drooping curved surface 32. FIG. Therefore, the light emitted from the LED chips 25a and 25b can be optically coupled to the light guide plate 13 efficiently. The hanging curved surface 32 made of an ellipse in section can be optically coupled to the light guide plate 13 by focusing light more than the hanging curved surface 32 made of a parabola in section. Therefore, from the viewpoint of improving the optical coupling efficiency, the drooping curved surface 32 is more preferably formed of a cross-sectional ellipse.

The positional relationship between the LED chip 25a · 25b and the focus _{f 2} of the drooping curved surface 32, with reference to FIG. 7 will be described in more detail. Figure 7 shows the positional relationship between the LED chip 25a · 25b and the focus _{f 2} of the drooping curved surface 32, FIG. 7 (a), when the light emitting point of the LED chip 25a is located at the end portion side than the focal point _{f 2} is a sectional view showing the optical path, FIG. 7 (b) is a sectional view showing an optical path when the light emitting point of the LED chips 25a coincides with the focal point _{f 2,} FIG. 7 (c), LED chips 25a emission point of a cross-sectional view showing an optical path when the middle portion than the focal f _2. Further, FIG. 7 (d) is a sectional view showing a case where the end portion of the center side of the LED chips 25a (the top flat surface 31 side) is on the end portion side than the focal point f _2, FIG. 7 (e) the end of the central portion side of the LED chip 25a is a cross-sectional view showing the case in the central portion than the focal f _2.

Positional relationship between the LED chip 25a · 25b and the focus _{f 2} of the drooping curved surface 32, as shown in FIG. 6 (b), (a) when the light emitting point of the LED chip 25a is located at the end portion side than the focal point _{f 2} , light emitting point (b) LED chip 25a may coincide with the focal point _{f 2,} cases are considered in the central portion than the focal _{f 2} is emitting point (c) LED chips 25a.

From FIG. 7 (a), when the light emitting point of the LED chip 25a is located at the end portion side than the focal point _{f 2,} light emitted from the LED chip 25a is optically coupled with the light guide plate 13 passes through all top flat surface 31 I understand that Further, from FIG. 7 (b), when the light emitting point of the LED chips 25a coincides with the focal point _{f 2,} light emitted from the LED chip 25a is present on all the top flat surface 31 (lower surface of the light guide plate 13) It focused on the focal point _{f 3.} On the other hand, when the light emitting point of the LED chips 25a is in the middle portion than the focal f _2, most of the light emitted from the LED chip 25a from FIG. 7 (c), the light guide plate without passing through the top flat surface 31 It can be seen that 13 does not photocouple.

Here, the LED chip 25a has a finite size. Therefore, the emitted light from the LED chip 25a enters the lower surface (lower flat surface 33) of the optical coupling member 30 at least in the size of the LED chip 25a. At this time, as shown in FIG. 7 (d), if the end of the central portion side of the LED chip 25a is located at the end portion side than the focal point f _2, all of the light emitted from the LED chip 25a is optically coupled since it emitted from the end portion side than the focal point f ₂ or focus f ₂ of the lower surface of the member 30, optically coupled with the light guide plate 13 passes through the top planar surface 31. Therefore, as shown in FIG. 7 (d), if the end of the central portion side of the LED chip 25a is located at the end portion side than the focal point f _2, it is possible to light coupling efficiency is improved.

On the other hand, as shown in FIG. 7 (e), if the end of the central portion side of the LED chip 25a is in the middle portion than the focal f _2, a part of the light emitted from the LED chip 25a is optically coupled The light is emitted from the center side with respect to the focal point f ₂ on the lower surface of the member 30, and the light is not optically coupled to the light guide plate 13. Therefore, as shown in FIG. 7 (e), the case where the end portion of the center side of the LED chip 25a is in the middle portion than the focal f _2, the light coupling efficiency is lowered, which is not preferable.

  Further, in a direction (hereinafter simply referred to as “width direction”) perpendicular to both the direction in which the optical coupling member 30 that is a belt-like body extends (hereinafter simply referred to as “extension direction”) and the thickness direction of the light guide plate 13. The width X of the top flat surface 31 is preferably the same as the width of the light irradiation region irradiated on the lower surface of the light guide plate 13 by the LED chips 25a and 25b. Thereby, the light radiated | emitted from LED chip 25a * 25b can be optically coupled with the light-guide plate 13 efficiently. FIG. 8A is a cross-sectional view schematically showing the relationship between the width of the top flat surface 31 and the width of the light irradiation region irradiated on the lower surface of the light guide plate 13, and FIG. The case where the width of the surface 31 is smaller than the width of the light irradiation region is shown, and FIG. 8C shows the case where the width of the top flat surface 31 is larger than the width of the light irradiation region. 8A to 8C show only light emitted from the LED chip 25a from the viewpoint of clarity of the drawing. In FIGS. 8A to 8C, the description of the prism 35a is omitted.

  Actually, light is also emitted from the LED chip 25b. In the configuration shown in FIG. 8A, the optical path of the light emitted from the LED chip 25 a intersects the optical path of the light emitted from the LED chip 25 b at the lower surface of the light guide plate 13. Here, the “light irradiation region” means a region on the lower surface of the light guide plate 13 irradiated with the radiated light of the LED chips 25a and 25b.

  When the width of the top flat surface 31 is smaller than the width of the light irradiation region (when the drooping curved surfaces 32 and 32 'are formed and the width of the top flat surface 31 is X1), the optical coupling efficiency is lowered, which is not preferable. As shown in FIG. 8B, the light emitted from the LED chip 25a is reflected by the drooping curved surface 32 and reaches a part surrounded by a dotted line. The light that reaches the portion surrounded by the dotted line leaks to the outside of the optical coupling member 30, or is reflected and reaches the LED chip 25b on the opposite side to become stray light L1. As a result, the optical coupling efficiency decreases.

  Further, when the width of the top flat surface 31 is larger than the width of the light irradiation region (when the drooping curved surfaces 32 and 32 ″ are formed and the width of the top flat surface 31 is X2), the optical coupling efficiency is lowered. It is not preferable. As shown in FIG. 8C, part of the light L <b> 2 that has passed through the top flat surface 31 and entered the light guide plate 13 is reflected again into the optical coupling member 30. As a result, the optical coupling efficiency decreases.

  Thus, in the direction perpendicular to the extending direction and the thickness direction of the light guide plate 13, the optical coupling efficiency is lowered even if the width of the top flat surface 31 is larger or smaller than the width of the light irradiation region. Therefore, it is preferable that the width of the top flat surface 31 is the same as the width of the light irradiation region irradiated on the lower surface of the light guide plate 13 by the LED chips 25a and 25b.

  The height of the light coupling member 30 is preferably such that the light emitted from the LED chips 25a and 25b hits the hanging curved surfaces 32 and 32 at least once. The LED chips 25a and 25b emit light at a predetermined radiation angle. Generally, the radiation angle of the LED chips 25a and 25b is 84 °. When a part of the light radiated at such a radiation angle is incident on the light guide plate 13 without being reflected by the hanging curved surfaces 32 and 32, there is a possibility that light is not reflected inside the light guide plate 13 and light leakage occurs. In order to avoid such light leakage, the height of the light coupling member 30 is set so that all of the emitted light from the LED chips 25a and 25b is reflected at least once by the hanging curved surfaces 32 and 32. It is preferable.

  As a result, in the backlight 10 in the liquid crystal display device 1 of the present embodiment, a strip-shaped light source module 20 is provided across the center of the screen of the liquid crystal display device 1 as shown in FIGS. Thereby, the emitted light from the light guide plate 13 having the luminance distribution shown in FIGS. 12A and 12B can be obtained. The luminance distribution that the center of the screen is bright matches the luminance distribution for displaying the liquid crystal display device 1 appropriately. Therefore, it can be said that it is superior to the conventional side edge type backlight. In addition to the central direct type light guide plate system shown in FIGS. 10A and 10B, the light source module 20 can be provided by the bottom direct type light guide plate system shown in FIGS. 11A and 11B.

  Also, in the backlight 10 of the present embodiment, unlike the conventional side edge type backlight, as shown in FIG. 13, there is no light source at the end of the liquid crystal panel 4, so the end of the liquid crystal panel 4 It is possible to provide the frame 6 directly. As a result, the frame size can be reduced.

  Moreover, in the backlight 10 in the liquid crystal display device 1 of this Embodiment, the light source module main body 20 provided with the LED chip 25 is arrange | positioned directly under the light-guide plate 13. As shown in FIG. Since the amount of expansion and contraction in the thickness direction of the light guide plate 110 is not large, it is not necessary to set a clearance in consideration of the amount of expansion and contraction of the light guide plate 13. Therefore, the optical coupling efficiency can be improved.

  Table 1 shows the result of comparing the optical coupling efficiency of the backlight 10 of the present embodiment and the side edge type backlight. In Table 1, the optical coupling efficiency is shown for a configuration in which the hanging curved surface 32 of the optical coupling member 30 has a parabolic cross section, a configuration in which the hanging curved surface 32 of the optical coupling member 30 has an elliptical cross section, and a side edge type backlight as a comparative example. Calculated.

  From the results in Table 1, it can be seen that the backlight 10 including the optical coupling member 30 has higher optical coupling efficiency than the side edge type backlight.

  Incidentally, as described above, the light source module 20 of the present embodiment includes the liquid crystal panel 4, the light guide plate 13 that irradiates the liquid crystal panel 4 with light, and the optical that couples light to the light guide plate 13, as shown in FIG. 15. An optical coupling member 30 as an element and LED chips 25 a and 25 b that emit incident light to the optical coupling member 30, and light that has returned to the optical coupling member 30 without being optically coupled to the light guide plate 13, is a top flat surface 31. Further, the liquid crystal panel 4, the light guide plate 13, the optical coupling member 30, and the LED chips 25a and 25b are arranged in this order. The LED chips 25a and 25b and the prisms 35a and 35b are provided on substantially the same plane, preferably on the same plane. In addition, the embodiment includes a part of the LED chip 25 (LED chips 25a and 25b) and a part of the prism 35 (prisms 35a and 35b) on the same plane. For example, if the upper surface of the LED chip 25 (LED chips 25a and 25b) and the lower surface of the prism 35 (prisms 35a and 35b) are substantially on the same plane, preferably on the same plane, this embodiment is included. .

  Here, as shown in FIG. 14, when the prisms 35 a and 35 b are not provided, if the LED chips 25 a and 25 b are arranged at positions shifted from predetermined positions with respect to the optical coupling member 30, light that is not integrated into the light guide plate 13 is emitted. It becomes stray light L3, and there is a risk of uneven brightness. Specifically, as shown in FIG. 14, a part of the light that is not integrated into the light guide plate 13 is emitted from the LED chip 25 a (toward the light guide plate 13) on the drooping curved surface 32 on the side opposite to the LED chip 25 a. The reflected light becomes stray light L3. More specifically, when the optical path is shifted due to the positional shift of the optical coupling member 30, light is irradiated also to an extra portion other than the optical coupling member 30, and downward (opposite to the light guide plate 13) by the extra portion. The light component reflected in the direction is stray light. In addition, when the optical coupling member 30 that is resistant to displacement is designed, the apparatus becomes large.

  On the other hand, in this embodiment, as shown in FIG. 15, prisms (first reflecting members) 35 (prisms 35a and 35b) are provided on substantially the same plane as the LED chips 25a and 25b, preferably on the same plane. It has been. The stray light can be directed again to the optical coupling member 30 by the prism 35. Thereby, even if the position of the optical coupling member 30 is shifted, stray light can be reduced and a decrease in the optical coupling rate can be prevented.

  In short, in the case where the prisms 35a and 35b are not provided, as shown in FIG. 14, mainly “the emission direction from the LED chips 25a and 25b on the hanging curved surface 32 on the same side as the LED chips 25a and 25b (on the light guide plate 13). The light reflected to the same side as the heading direction ”enters the top flat surface 31. On the other hand, when the prisms 35a and 35b are provided, as shown in FIG. Light reflected on the same side as the direction toward the light plate 13), and “Emission direction from the LED chips 25 a and 25 b on the hanging curved surface 32 on the same side as the LED chips 25 a and 25 b (direction toward the light guide plate 13). The light reflected in the opposite direction to the light guide plate 13 by the hanging curved surface 32 opposite to the LED chips 25a and 25b and further reflected by the prisms 35a and 35b "is flat on the top. Incident on the surface 31.

  In addition, the light source module 20 of the present embodiment has (i) an increased manufacturing tolerance and facilitates assembly, (ii) a larger light source can be used, (iii) an optical coupling member (lens) ) Can be reduced in size, and (iv) it can be combined with a thinner light guide plate.

  The prism 35 (prisms 35a and 35b) will be described in detail below.

  The formation position of the prism 35 is a place where the stray light component is condensed on the lower surface of the optical coupling member 30 (surface opposite to the light guide plate 13).

  The shape of the prism 35 is not particularly limited, and is a shape such that the stray light component is recombined with the light guide plate 13. Specifically, the prism 35 has an LED chip such that the angle between the prism 35 and the surface on which the LED chip 25 is disposed is preferably in the range of 35 ° to 50 °, more preferably 40 ° to 46 °. It is preferable to have a re-reflecting surface that is provided upright starting from the proximal end from 25. Thus, if set to 35 ° to 50 °, 30% or more of stray light components can be recombined. If set to 40 ° to 46 °, 30% or more of stray light components can be recombined. Can be made. Further, the light reflected by the re-reflecting surface and incident on the light guide plate 13 intersects with the light incident on the light guide plate 13 without returning to the optical coupling member 30 (in the opposite direction).

  The prism 35 can be formed by, for example, hollowing out a part of the optical coupling member 30 to the above shape.

  The height of the prism 35 (the distance in the thickness direction of the light guide plate 13) is a height that does not hinder the light emitted from the LED chip 25.

  The reflecting surface (the re-reflecting surface) of the prism 35 is preferably a surface capable of total reflection. However, depending on the angle between the stray light and the re-reflecting surface, a mirror surface (mirror surface), a surface on which a metal film is formed, and the like can be used properly. The surface on which the metal film is formed can be manufactured by forming a vapor deposition film of metal or the like.

  The manufacturing tolerance in the light source module 20 of the present embodiment will be described in detail below.

  FIG. 16 shows the relationship between the amount of misalignment between the LED chip and the optical coupling member (lens) and the coupling efficiency, when there is a prism (graph A in FIG. 16) and when there is no prism (B in FIG. 16). It is shown in comparison with the graph.

  As a result, when there is no prism, the coupling efficiency is reduced by 10% or more due to a positional deviation of 0.2 mm. On the other hand, when the prism according to the present embodiment is provided, it can be seen that the coupling efficiency is constant even if a positional deviation of 0.2 mm occurs. Further, the 10% coupling efficiency is lowered when a positional deviation of 0.3 mm occurs, and the tolerance when the prism is provided is 1.5 times that when the prism is not provided.

  In other words, as shown in FIG. 14, the light coupling member has a structure in which a cylindrical light coupling member and a light guide plate are bonded to each other, and light is incident from the vicinity of the curved surface of the cylinder shape so that light is directly emitted from the LED chip. Can be prevented from leaking. However, when the LED chip is disposed at a position deviated from a predetermined position, as shown in FIG. 14, light that is not coupled to the light guide plate becomes stray light, and luminance unevenness occurs. As a countermeasure against stray light, as shown in FIG. 15, a prism shape is provided at the bottom of a cylindrical optical coupling member, and light that is not coupled to the light guide plate and reflected by a curved surface opposite to the LED chip is converted into a prism. It is re-coupled to the light guide plate by reflecting in shape. As a result, the optical coupling member can be made more resistant to displacement while being downsized.

  In the present embodiment, the light source module body 20 is provided with two rows of LED chips 25a and 25b. However, the present invention is not necessarily limited to this. For example, as shown in FIGS. 17A and 17B, it is possible to adopt a configuration in which one row of LED chips 25 is arranged only on one side of the optical coupling member 40.

  Further, as a configuration in which one row of LED chips 25 is arranged, a configuration as shown in FIG. 18 may be used. Hereinafter, the modification of the backlight 10 of this embodiment is further explained in full detail. FIG. 18 is a cross-sectional view schematically showing a modified example of the backlight 10.

  As shown in FIG. 18, the optical coupling member 30 'has two reflecting surfaces 32'. The two reflecting surfaces 32 ′ are formed so as to constitute a V-shaped surface extending along the vertical or horizontal center line L in the light guide plate 13. Two top flat surfaces 31 are formed so as to be connected to the two reflecting surfaces 32 ′ and symmetrical with respect to the center line L.

  In the configuration shown in FIG. 18, the LED chips 25 are arranged in a line. And the light radiated | emitted from LED chip 25 is branched in two directions by the V-shaped surface comprised by the two reflective surfaces 32 '. The two reflecting surfaces 32 ′ constituting the V-shaped surface may be any surfaces that totally reflect the light emitted from the LED chip 25, and are composed of, for example, a cross-sectional parabola or a cross-sectional ellipse shown in FIGS. The hanging curved surface 32 may be used.

  Even in the configuration shown in FIG. 18, it is possible to prevent light emitted from the LED chip 25 from leaking directly to the outside, and to improve the optical coupling efficiency. Further, the light guide plate 13 and the optical coupling member 30 are separate members, and the optical coupling member 30 is bonded to the flat light guide plate 13 that is normally used. For this reason, the process to the light-guide plate 13 becomes unnecessary, and cost reduction can be implement | achieved.

  Further, in the configuration shown in FIG. 18, the light emitted from the LED chips 25 arranged in a row is branched into two optical paths on the V-shaped surface and emitted from both sides in the width direction of the optical coupling member 30 ′. . Therefore, there is an advantage that the arrangement of the LED chips 25 is simplified and the labor required for mounting the LED chips 25 can be reduced.

  On the other hand, in the configuration shown in FIG. 18, since the emitted light from the LED chip 25 is branched into two optical paths on the V-shaped surface, the luminance of the light guide plate 13 region directly above the LED chip 25 is reduced. The problem of doing is left. However, this problem can be solved by arranging the optical coupling members 30 ′ in a double row and making light incident on a dark portion (near the V-shaped surface along the center line L) on the optical coupling member 30 ′. Therefore, in the configuration shown in FIG. 18, the optical coupling members 30 ′ are preferably arranged in a double row. Note that, from the viewpoint of improving the luminance in the vicinity of the center line L in the light guide plate 13, a configuration including two rows of LED chips 25a and 25b as shown in FIG. 4 is preferable.

  Further, in the configuration shown in FIG. 18, there remains a problem that the luminance of the emitted light greatly fluctuates when the LED chip 25 is displaced even a little. This problem can be solved by improving the positioning accuracy of the LED chip 25.

  Specifically, as shown in FIG. 18, the above problem can be solved by providing a prism 35. If the prism 35 is provided, stray light can be reduced and a decrease in the optical coupling rate can be prevented, so that luminance unevenness can be suppressed.

  In addition, this invention can also be expressed as follows as an illuminating device.

  A substantially flat light guide plate, a light source and a light re-reflecting member disposed below the light guide plate, and a light coupling member disposed between the light guide plate and the light source, the light coupling member The surface portion includes a light coupling portion that is in contact with the light guide plate in a plane substantially parallel to the light guide plate, and a light reflection portion that is inclined with respect to the plane of the top portion and has a flat surface or a curved surface, Light from the light source is irradiated in a direction inclined from a direction perpendicular to the light guide plate to an irradiation region including at least a part of the light coupling part and a part of the light reflecting part. The light component irradiated to the reflection unit is reflected by the light reflection unit, and further re-reflected by the light re-reflection member to be applied to the light coupling unit.

  The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope shown in the claims, and the present invention is also applied to an embodiment obtained by appropriately combining technical means disclosed in the embodiment. It is included in the technical scope of the 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.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Diffusion sheet 3 Prism sheet 4 Liquid crystal panel 10 Backlight (light source module)
11 Chassis 11a, 11b Chassis 12 Reflective sheet (second reflective member)
13 Light guide plate 14 Slit 20 Light source module body 23 Spacer 23a / 23b Spacer 24 LED substrate 24a / 24b LED substrate 25 LED chip (light source, LED)
25a / 25b LED chip (light source, LED)
30 Optical coupling member 31 Flat top surface 32 Hanging surface (reflection surface)
33 Flat bottom surface 34 Recess 35 Prism (first reflecting member)
35a / 35b prism (first reflective member)

Claims (13)

A flat light guide plate;
A light source disposed below the light guide plate;
An optical coupling member disposed between the light guide plate and the light source;
The optical coupling member has a top flat surface that abuts on a surface parallel to the light guide plate, and a reflective surface that reflects light from a light source and guides the light to the top flat surface.
The light source plate further includes a first reflecting member provided on the same surface as the light source, which reflects light returning to the light coupling member without being optically coupled to the light guide plate toward the top flat surface. A light source module. The first reflecting member has a re-reflecting surface,
The light reflected by the re-reflecting surface and optically coupled to the light guide plate intersects with the light optically coupled to the light guide plate without returning to the light coupling member. Light source module.   3. The light source module according to claim 1, wherein the first reflecting member reflects light reflected by the reflecting surface in a direction opposite to the light guide plate toward the flat top surface. 4. .   4. The light source module according to claim 2, wherein the re-reflecting surface is a mirror surface or a surface on which a metal film is formed.   The light source module according to any one of claims 1 to 4, wherein all of the light emitted from the light source strikes the reflecting surface at least once. The reflective surface is a curved surface formed by hanging from the top flat surface,
The light source module according to claim 1, wherein light emitted from the light source is condensed on the top flat surface. The reflecting surface is a parabolic surface whose section is a parabola,
The light source module according to claim 1, wherein a focal position of the paraboloid is closer to a central portion of the optical coupling member than the light source. The reflecting surface is an ellipsoid whose cross section is an ellipse,
The one focal position of the elliptical surface is closer to the center of the optical coupling member than the light source, and the other focal position is on the lower surface of the light guide plate. The light source module of any one of -7. The light source is composed of a plurality of LEDs,
The light source module according to any one of claims 1 to 8, wherein the reflection surface reflects light emitted from each LED and guides the light to the top flat surface. The top flat surface of the optical coupling member is provided on a vertical or horizontal center line of the light guide plate,
Two reflecting surfaces are formed so as to be symmetrical with respect to the center line,
The light source module according to claim 9, wherein the LEDs are provided in two rows so as to correspond to the reflective surface.   In the direction perpendicular to both the direction of the center line and the thickness direction of the light guide plate, the width of the top flat surface is the same as the width of the light beam irradiation region on the lower surface of the light guide plate irradiated by the light from the LED. The light source module according to claim 10, wherein the light source module is a light source module. The optical coupling member has two reflection surfaces, and the two reflection surfaces are formed so as to constitute a V-shaped surface extending along a vertical or horizontal center line of the light guide plate,
The top flat surface is formed so as to be connected to two reflecting surfaces and symmetrical with respect to the center line,
The light source module according to claim 9, wherein the LEDs are provided in a line so that the emitted light branches off at the V-shaped surface.   An electronic apparatus comprising the light source module according to claim 1.

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