JP2012185941A - Light source module and electronic equipment equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source module with coupling efficiency from a light source to a light guide plate enhanced and capable of improving light utilization efficiency, as well as an electronic equipment equipped with the same.SOLUTION: The light source module is provided with a light guide plate 13, an LED 23 arranged below the light guide plate 13, and an optical coupling member 30 coupling the light from the LED 23 to be guided inside the light guide plate 13. The optical coupling member 30 is provided with a concave part 34 formed avoiding an optical path of the light from the LED 23. The concave part 34 is provided with a reflective sheet 35 for reflecting to the light guide plate 13 light which returns to the optical coupling member 30 without being optically coupled with the light guide plate 13.

Description

  The present invention relates to a direct type light source module in which a light source is provided below a light guide plate, and an electronic apparatus including the same. More specifically, the present invention relates to a light source module suitable as a backlight and an electronic apparatus such as a liquid crystal display device including the light source module.

  Liquid crystal display devices are used in various fields because they can be made thin and light. In a liquid crystal display device such as a liquid crystal television, a backlight including a light guide plate that emits light from a light source in a planar shape by the light guide plate is often used. Further, an LED (Light Emitting Diode) is used as a light source of the backlight.

  The arrangement of the light source of the backlight includes a direct type and a side edge type (also referred to as a side light type). A general direct type is a system in which LEDs are arranged in a matrix under a 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. When a diffusing lens is used, light is diffused and applied to the panel, so that the panel can be applied uniformly with a small number of light sources.

  However, in a general direct type backlight, in order to diffuse and uniformly irradiate light, it is necessary to take a certain distance between the light source and the panel. Therefore, a direct type backlight using a light guide plate has been studied. In the direct type, a light source is disposed directly below the light guide plate (directly below the liquid crystal display panel), and light enters the light guide plate from below the light guide plate.

  On the other hand, in the side light type, light sources are arranged on both end faces in the longitudinal direction of the light guide plate, and light enters the light guide plate from each end face.

  However, in the side edge type backlight, the light guide plate expands and contracts due to thermal expansion. In particular, the length of the light guide plate in the longitudinal direction is large. 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 light from the light source to the light guide plate is deteriorated due to the presence of the gap. As the light guide plate becomes larger, the amount of expansion and contraction of the light guide plate increases, and this problem becomes more prominent. Therefore, in the case of a large light guide plate, the gap between the light source and the light guide plate must be increased, and the incident efficiency is likely to be further reduced.

  On the other hand, in the case of a direct backlight, the amount of expansion and contraction in the thickness direction of the light guide plate is not large, so that the LEDs can be disposed close to the light guide plate. For this reason, the problem like a side edge type backlight does not arise. Therefore, the direct type backlight can improve the light coupling efficiency and light utilization efficiency to the light guide plate than the side edge type backlight.

  By the way, for example, Patent Document 1 discloses a backlight for the purpose of increasing the coupling efficiency to the light guide plate. Specifically, the backlight of Patent Document 1 includes a polygonal column-shaped light coupling portion in order to introduce light from the light source into the light guide plate. This optical coupling part is in contact with the surface of the light guide plate. The light source is disposed obliquely with respect to the contact surface of the light guide plate with the optical coupling portion. Thus, light from the light source is introduced into the light guide plate in an oblique direction with respect to the light guide plate via the optical coupling member, and is optically coupled to the light guide plate.

Japanese Patent Laying-Open No. 2008-257721 (released on October 23, 2008)

  However, in the backlight of Patent Document 1, the light reflected by the light exit surface of the light guide plate and the light reflected by the interface between the light guide plate and the optical coupling portion are not used. For this reason, it is difficult to say that the coupling efficiency of the backlight of Patent Document 1 is high. That is, the backlight of Patent Document 1 still has a problem that the coupling efficiency from the light source to the light guide plate is low and the light utilization efficiency is poor.

  The present invention has been made in view of the above-described conventional problems, and its purpose is to improve the coupling efficiency from the light source to the light guide plate in a direct light source module in which a light source is provided below the light guide plate, It is an object of the present invention to provide a light source module capable of improving the light use efficiency and an electronic device including the same.

  In order to solve the above problems, a light source module of the present invention is provided between a light guide plate, a light source provided below the light guide plate, and the light source and the light guide plate. An optical coupling member that couples light so as to guide light, the light source is disposed on a lower surface of the optical coupling member, and the optical coupling member has an optical coupling portion with a light guide plate on an upper surface, and a lower surface A recess is formed so as to avoid the light source and include at least a part below the optical coupling portion, and light that has returned to the optical coupling member without being optically coupled to the light guide plate is received in the concave portion. The first reflection member that reflects on the light guide plate is provided.

  The light source module of the present invention is a direct light source module in which a light source is provided below a light guide plate. This light source module combines light so that light emitted from a light source disposed on the lower surface of the light coupling member is guided inside the light guide plate (that is, obliquely incident on the light guide plate). An optical coupling member is provided.

  According to the above invention, the optical coupling member is formed with the recess so as to avoid the light source. Further, a first reflecting member is provided in the recess. The concave portion is formed so as to include at least a part below the optical coupling portion with the light guide plate. For this reason, the first reflecting member is disposed closer to the lower surface of the light guide plate than the lower surface (lower end) of the optical coupling member. That is, the distance between the light guide plate and the first reflecting member can be reduced. Thereby, the light which is not optically coupled to the light guide plate and returns to the optical coupling member is reflected to the light guide plate by the first reflecting member. Therefore, the coupling efficiency from the light source to the light guide plate can be increased, and the light utilization efficiency can be improved.

  In addition, the recessed part should just be provided avoiding at least one part of the optical path of the light from a light source, and may be provided avoiding all the optical paths of the light from a light source. In other words, the recess is preferably provided so as not to block the optical path of light from the light source. This makes it possible to reduce the material cost of the optical coupling member as well as to reduce the weight of the optical coupling member.

  Further, by forming the concave portion in the optical coupling member, the thickness of the optical coupling member can be made uniform as compared with the case where the concave portion is not formed. For this reason, even if the optical coupling member is produced by molding or the like, molding defects such as shrinkage are unlikely to occur.

  Note that Patent Document 1 does not describe the provision of the recess in the present invention nor the provision of the first reflecting member. That is, in Patent Document 1, 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 again to the light guide plate.

In the light source module of the present invention, the optical coupling member has a flat top surface that abuts the lower surface of the light guide plate in a plane,
It is preferable that a second reflecting member for reflecting light guided through the light guide plate is provided on the lower surface of the light guide plate so as to avoid a contact portion with the top flat surface.

  According to said invention, the optical coupling member has the top flat surface which contact | abuts the lower surface of a light-guide plate in a plane. For this reason, the 2nd reflective member which reflects the light which guides the inside of a light guide plate cannot be provided in the contact part of a light guide plate and a top flat surface. As a result, light that is not optically coupled to the light guide plate is likely to return to the optical coupling member. Therefore, in particular, at the contact portion (joint portion) between the light guide plate and the top flat surface, the optical characteristics such as reduction in coupling efficiency and occurrence of luminance unevenness are likely to be affected.

  However, according to said invention, the light which returned to the optical coupling member, without optically coupling with a light guide plate, is reliably reflected by the 1st reflection member to a light guide plate. Thereby, in the contact part of a light-guide plate and a top flat surface, the coupling efficiency from a light source to a light-guide plate can be improved, and light utilization efficiency can be improved. Therefore, the light extraction efficiency can be made uniform between the region where the second reflecting member is formed and the region where the second reflecting member is not formed. Therefore, the luminance uniformity of the light source module can be improved.

  In addition, the top flat surface of the optical coupling member may be in direct contact with the light guide plate, or may be in contact with the light guide plate through an adhesive portion.

In the light source module of the present invention, the concave portion has a flat surface parallel to the optical coupling portion,
The first reflecting member is preferably provided on the flat surface.

  According to said invention, the 1st reflection member is provided on the flat surface formed in the recessed part. Therefore, it is possible to easily form the first reflecting member in the recess.

  In the light source module of the present invention, the flat surface is preferably parallel to the lower surface of the light guide plate.

  According to the above invention, the top flat surface of the optical coupling member and the flat surface on which the first reflecting member is provided are both parallel to the lower surface of the light guide plate. Therefore, diffusion of light can be suppressed on the flat surface where the first reflecting member is provided.

  In the light source module of the present invention, the first reflecting member has a cross-sectional width perpendicular to the longitudinal direction of the optical coupling member that is larger than the width of the top flat surface in the same direction. The light source module according to claim 2, wherein the light source module is a light source module.

  As described above, the second reflecting member cannot be provided at the contact portion between the light guide plate and the top flat surface. For this reason, the area | region where the 2nd reflective member is not provided exists in the lower surface of a light-guide plate. On the other hand, the first reflecting member is disposed closer to the lower surface of the light guide plate than the lower surface of the optical coupling member.

  According to the above invention, when the light source module is viewed from the top, the first reflecting member apparently covers the region where the second reflecting member is not provided. Thereby, in the contact part of a light-guide plate and a top flat surface, the coupling efficiency from a light source to a light-guide plate can be improved, and light utilization efficiency can be improved. Therefore, the light extraction efficiency can be made uniform between the region where the second reflecting member is formed and the region where the second reflecting member is not formed. Therefore, the luminance uniformity of the light source module can be improved.

In the light source module of the present invention, the light source includes a plurality of LEDs, and the LEDs are provided in two rows along the longitudinal direction of the optical coupling member.
It is preferable that the optical coupling member has an arcuate or arcuate shape in which a cross section in a direction perpendicular to the LED arrangement direction connects the LEDs arranged in the two rows.

  According to said invention, the said cross section in an optical coupling member becomes a dome shape. And LED is arrange | positioned in the both ends of the lower surface of an optical coupling member in the cross section perpendicular | vertical with respect to the longitudinal direction of an optical coupling member. Therefore, it is possible to make the luminance distribution uniform in the light guide plate.

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

  According to said invention, the electronic device provided with the light source module which can improve the coupling efficiency from a light source to a light-guide plate and can improve light utilization efficiency can be provided.

  In the specification of the present application, “vertical” and “parallel” do not only indicate that they are completely vertical or completely parallel, but are within a range in which substantially the same effect can be obtained. Good. That is, “vertical” and “parallel” mean “substantially vertical” and “substantially parallel”.

  In the light source module and the electronic device of the present invention, as described above, the optical coupling member has an optical coupling portion with the light guide plate on the upper surface, avoids the light source on the lower surface, and A concave portion is formed so as to include at least a part below the optical coupling portion, and the first portion that reflects the light that returns to the optical coupling member without optical coupling to the light guide plate to the light guide plate is reflected in the concave portion. It is a structure provided with a reflecting member. Therefore, the light source module capable of increasing the coupling efficiency from the light source to the light guide plate and improving the light utilization efficiency, and the electronic device including the light source module are obtained.

It is sectional drawing which shows the structure of the light source module of this invention. It is a disassembled perspective view which shows the structure of the said liquid crystal display device. 1 is a cross-sectional view illustrating a configuration of a liquid crystal display device according to an embodiment of the liquid crystal display device of the present invention. It is sectional drawing which shows the structure of 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 LED vicinity. . (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 LED vicinity. 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 the 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. In the light source module of FIG. 1, it is sectional drawing which shows a structure when not forming a recessed part in an optical coupling member. It is sectional drawing which shows the structure of the modification of the light source module of this invention. (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.

  Embodiments of the present invention will be described with reference to the drawings.

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

  As shown in FIG. 2, the liquid crystal display 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 (back side). .

  The backlight 10 includes a light source module 20, a chassis 11 having a single opening 11a, a reflection sheet (second reflection sheet) 12, and a light guide plate 13 in order from the bottom. In addition, as shown in FIG. 3, the light source module 20 is provided with a sheet-like heat sink 22 on a light source holder 21 formed in a band shape. LED boards 24a and 24b on which LEDs (Light Emitting Diodes) 23a and 23b are mounted are provided. In the present embodiment, the LEDs 23a and 23b are used as the light source. However, the present invention is not limited to this, and for example, an organic EL light emitting element or an inorganic EL light emitting element can also be used.

  A plurality of the LEDs 23a and 23b are provided in parallel in two rows, and the optical coupling member 30 is provided above the plurality of LEDs 23a and 23b. The LEDs 23 a and 23 b are disposed on the lower surface of the optical coupling member 30. In addition, a hollow recess 34 is formed at the center of the lower end of the optical coupling member 30. The recess 34 extends in the longitudinal direction of the optical coupling member 30. Further, the optical coupling member 30 connects the LEDs 23a and 23b in which the cross section perpendicular to the arrangement direction of the LEDs 23a and 23b (that is, the cross section perpendicular to the longitudinal direction of the optical member 30) is arranged in two rows. It is like an arc or arc. That is, the optical coupling member 30 has a dome shape.

  That is, as shown in FIG. 4, 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. An optical coupling member 30 and LEDs 23a and 23b that emit incident light to the optical coupling member 30, and the liquid crystal panel 4, the light guide plate 13, the optical coupling member 30, and the LEDs 23a and 23b are arranged in this order. It is made up of. Therefore, the backlight 10 in the liquid crystal display device 1 of the present embodiment is a backlight 10 directly under the light source in which the LEDs 23 a and 23 b are provided below the light guide plate 13.

  Here, in this embodiment, as shown in FIGS. 5 (a) and 5 (b), the optical coupling member 30 has a substantially semicircular cross section provided between the light guide plate 13 and the LED 23, that is, a substantially semicircular cross section. The light coupling member 30 is made of the same resin as that of the light guide plate 13. Specifically, as shown in FIG. 5A, the surface of the optical coupling member 30 on the light guide plate 13 side is a top flat surface (optical coupling portion) 31 that contacts the flat light guide plate 13 and the top flat surface. It consists of drooping curved surfaces 32 and 32 that respectively hang from the surface 31 to both ends. 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.

  The drooping curved surfaces 32 and 32 can be, for example, a cross-sectional parabola shown in FIG. However, the present invention is not necessarily limited to this, and a cross-sectional ellipse may be used as shown in FIGS. In the present invention, a curved shape such as an arc shape having a top flat surface 31 or a plane inclined obliquely from the top flat surface 31 is not limited to a parabola or a cross ellipse. The surface of the optical coupling member 30 opposite to the light guide plate 13, 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. In other words, the recess 34 is formed so as to include at least a part below the top flat surface 31. The recess 34 is a cavity formed so as to avoid at least part of the optical path of light from the LED 23. A reflective sheet 35 (first reflective member) is provided in the concave portion 34 (surface on which the concave portion 34 is formed).

  LEDs 23a and 23b are provided close to each other below the lower flat surfaces 33 and 33 of the optical coupling member 30, respectively. As shown in FIGS. 5B and 6B, these LEDs 23a and 23b are preferably present on the end side with respect to the focal position F of the drooping curved surfaces 32 and 32 having a cross-sectional parabola or a cross-sectional ellipse. Accordingly, for example, as shown in FIG. 5A, for example, the light emitted from the LED 23 a is reflected by the drooping curved surface 32 of the cross-sectional parabola of the optical coupling member 30, and the reflected light is flat at the top of the optical coupling member 30. It reaches the surface 31 and enters the light guide plate 13 while maintaining the arrival direction. A reflective 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. Further, the light that has traveled by total reflection collides with a light scatterer (light path conversion unit) (not shown) provided on the light guide plate 13, thereby changing the angle of traveling through the light guide plate 13 and breaking the total reflection condition. Then, 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 23b also travels symmetrically with the light from the LED 23a, as shown in FIG.

  Such an optical path is the same in the optical coupling member 30 having an elliptical cross section shown in FIGS. Specifically, as shown in FIG. 6A, the light emitted from the LED 23 b is reflected by a drooping curved surface 32 having a cross-sectional ellipse of the optical coupling member 30, and the reflected light is the top flat surface of the optical coupling member 30. 31 and enters the light guide plate 13 while maintaining the direction of arrival. Then, the light incident on the light guide plate 13 travels by being totally reflected on the inner right side of the light guide plate 13 shown in FIG. 6A, and collides with a light scatterer which is an optical path changing unit (not shown). The angle of traveling inside changes, 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 23b also travels symmetrically with the light from the LED 23a, as shown in FIG.

  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. 9A and 9B 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.

  Moreover, in the backlight 10 of this Embodiment, the light of LED23a * 23b is introduced from the downward direction of the light-guide plate 13. FIG. Therefore, as shown in Table 1, the light utilization efficiency of the conventional side edge type backlight is 75%, whereas the light utilization efficiency of the backlight 10 of the present embodiment is 88%. It is also excellent in light utilization efficiency.

  Also, in the backlight 10 of the present embodiment, unlike the conventional side edge type backlight, as shown in FIG. 10, 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, as shown in Table 1, the frame size can be reduced to 6 mm or less.

  Incidentally, as described above, the light source module 20 of the present embodiment is a direct light source module in which the LED 23 is provided below the light guide plate 13. Further, as shown in FIG. 1, the light source module 20 is configured so that light emitted from the LED 23 is guided in the light guide plate 13 (that is, obliquely incident on the light guide plate 13). The optical coupling member 30 is coupled. Further, the optical coupling member 30 is formed with a recess 34 so as to avoid at least a part of the optical path of light from the LED 23. Further, a reflection sheet 35 is provided in the recess 34.

  Here, as shown in FIG. 11, when the concave portion 34 of the optical coupling member 30 in FIG. 1 is not provided, the reflection sheet 35 is provided below the optical coupling member 30. For this reason, the distance A from the lower surface (top flat surface 31) of the light guide plate 13 to the reflection sheet 35 is separated. Further, the distance from the lower surface of the light guide plate 13 to the lower surface of the light coupling member 30 in the arrangement portion of the LED 23, and the light coupling member 30 from the lower surface of the light guide plate 13 to the lower surface of the light guide plate 13 and directly below the top flat surface 31. The distance to the lower surface of is equal.

  On the other hand, in this embodiment, the optical coupling member 30 has a recess 34 as shown in FIG. 1, and the reflection sheet 35 is provided in the recess 34. For this reason, the reflective sheet 35 is disposed closer to the lower surface of the light guide plate than the lower surface (lower flat surface 33) of the optical coupling member 30. That is, the distance A ′ from the lower surface (the top flat surface 31) of the light guide plate 13 to the reflection sheet 35 is shorter than the distance A in FIG. 11. Further, the distance from the lower surface of the light guide plate 13 to the recess 34 is shorter than the distance from the lower surface of the light guide plate 13 to the lower surface of the optical coupling member 30. That is, the distance between the light guide plate 13 and the reflection sheet 35 can be reduced. Thereby, the light that is not optically coupled to the light guide plate 13 and returns to the optical coupling member 30 is reflected by the reflection sheet 35 to the light guide plate 13. Therefore, the coupling efficiency from the LED 23 to the light guide plate 13 can be increased, and the light utilization efficiency can be improved.

  The recess 34 may be provided so as to avoid at least a part of the optical path of the light from the LED 23, and may be provided so as to avoid the entire optical path of the light from the LED 23. In other words, the recess 34 is preferably provided so as not to block the optical path of the light from the LED 23. Thereby, it becomes possible to reduce the material cost of the optical coupling member 30 while reducing the weight of the optical coupling member 30.

  Moreover, it is preferable that LED23 provided in the lower surface of the optical coupling member 30 is arrange | positioned so that it may not overlap directly under the top flat surface 31 which is an optical coupling part. In this way, if the portion directly below the top flat surface 31 and the location where the LED 23 is disposed do not overlap, it is not necessary to configure the lower surface (lower flat surface 33) of the optical coupling member 30 as a single flat surface. That is, the arrangement surface of the LED 23 and the arrangement surface of the reflection sheet 35 provided in the recess 34 formed immediately below the top flat surface 31 can be completely separated and configured with different surfaces. Thereby, the recessed part 34 can be formed in all right under the top flat surface 31.

  Further, as shown in FIG. 11, when the concave portion 34 is not formed, the thickness of the optical coupling member 30 is the thickest at the central portion (distance A), and becomes thinner as the distance from the central portion increases. That is, the thickness of the optical coupling member 30 is not uniform. On the other hand, as shown in FIG. 1, the concave portion 34 is a hollow portion obtained by scraping unnecessary portions (portions through which light does not pass) inside the optical coupling member 30. For this reason, compared with the case where the recessed part 34 is not formed, the thickness of the optical coupling member 30 can be made uniform. For this reason, even if the optical coupling member 30 is produced by molding or the like, molding defects such as shrinkage hardly occur.

  The formation method of the recessed part 34 to the optical coupling member 30 is not specifically limited. For example, if the optical coupling member 30 is molded using a mold in which the concave portion 34 is formed, the optical coupling member 30 having the concave portion 34 is integrally formed from the beginning. Further, the recesses 34 can be formed by cutting the optical coupling member 30.

  Note that Patent Document 1 does not describe the provision of the recess 34 or the reflection sheet 35 in the present invention. That is, in Patent Document 1, 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 again to the light guide plate.

  Further, in the backlight 10 of the present embodiment, the light emitted from the LED 23 radiates in the direction perpendicular to the light guide plate 13 and enters 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.

  However, it is generally difficult to dispose the LEDs obliquely so as to enter the oblique direction with respect to the light guide plate as in the technique disclosed in Patent Document 1. For example, in order to arrange the LEDs diagonally, it is necessary to install a pedestal for holding the LED diagonally on the chassis and then mount the LED on the pedestal from an oblique direction. For this reason, the technique disclosed in Patent Document 3 makes it difficult to assemble the backlight and cannot be put to practical use.

  On the other hand, in the backlight 10 of the present embodiment, the LEDs 23 are arranged so that the emitted light radiates in the direction perpendicular to the light guide plate 13. That is, unlike the technique described in Patent Document 3, it is not necessary to dispose the LEDs obliquely so as to be incident obliquely with respect to the light guide plate, and the LEDs 23 are perpendicular to the flat chassis 11 and from directly above. It is only implemented. Therefore, in the backlight 10 of the present embodiment, the assembling method and structure can be simplified. As described above, the backlight 10 according to the present embodiment has an advantage that the LED 23 can be mounted vertically in terms of structure compared to the technique of Patent Document 1.

  Further, in the light source module 20, the optical coupling member 30 has a top flat surface 31 that abuts the lower surface of the light guide plate 13 in a plane, and the reflective sheet 12 is provided on the lower surface of the light guide plate 13. preferable. The reflection sheet 12 is provided so as to avoid a contact portion between the light guide plate 13 and the top flat surface 31, and reflects light guided through the light guide plate 13.

  In such a configuration, the optical coupling member 30 has a top flat surface 31 that abuts the lower surface of the light guide plate 13 in a plane. For this reason, the reflection sheet 12 that reflects the light guided through the light guide plate 13 cannot be provided at the contact portion between the light guide plate 13 and the top flat surface 31. As a result, the light that is not optically coupled to the light guide plate 13 easily returns to the optical coupling member 30. Therefore, in particular, the contact portion (joint portion) between the light guide plate 13 and the top flat surface 31 is liable to affect the optical characteristics such as a decrease in coupling efficiency and occurrence of luminance unevenness.

  However, the light that is not optically coupled to the light guide plate 13 and returns to the optical coupling member 30 is reliably reflected to the light guide plate 13 by the reflection sheet 35. Thereby, in the contact part of the light-guide plate 13 and the top flat surface 31, the coupling efficiency from LED23 to the light-guide plate 13 can be improved, and light utilization efficiency can be improved. Therefore, the light extraction efficiency can be made uniform between the region where the reflection sheet 12 is formed and the region where the reflection sheet 12 is not formed. Therefore, the luminance uniformity of the light source module can be improved.

  The top flat surface 31 of the optical coupling member 30 may be in direct contact with the light guide plate 13 or may be in contact with the light guide plate 13 through an adhesive portion.

  On the other hand, in the optical coupling member 30 of FIG. 1, a portion of the concave portion 34 facing the top flat surface 31 is a curved surface. However, the shape of the portion of the recess 34 facing the top flat surface 31 is not limited to a curved surface. For example, as shown in FIG. 12, it is preferable that the portion of the recess 34 that faces the top flat surface 31 is a flat surface. That is, it is preferable that the recessed part 34 has the flat surface 34a parallel to the top flat surface 31, and the reflection sheet 35 is provided in the said flat surface 34a. According to this configuration, the reflection sheet 35 is provided on the flat surface 34 a formed in the recess 34. Therefore, it is possible to easily form the reflective sheet 35 in the recess 34.

  Further, the flat surface 34 a is preferably parallel to the lower surface of the light guide plate 13. According to this configuration, the top flat surface 31 of the optical coupling member 30 and the flat surface 34 a on which the reflection sheet 35 is provided are both parallel to the lower surface of the light guide plate 13. Therefore, diffusion of light can be suppressed on the flat surface 34a on which the reflection sheet 35 is provided.

  Furthermore, in the configuration of FIG. 12, the reflection sheet 35 has a cross-sectional width X perpendicular to the longitudinal direction of the optical coupling member 30 greater than the width Y of the top flat surface 31 in the same direction. Further, the width X is larger than the width Z in the same direction of the area where the reflection sheet 12 is not provided on the lower surface of the light guide plate 13.

  As described above, the reflective sheet 12 cannot be provided at the contact portion between the light guide plate 13 and the top flat surface 31. For this reason, an area where the reflection sheet 12 is not provided exists on the lower surface of the light guide plate 13. On the other hand, the reflection sheet 35 is disposed closer to the lower surface of the light guide plate 13 than the lower surface of the optical coupling member 30.

  For this reason, when the light source module (light guide plate 13) is viewed from above as shown in FIG. 12, the reflection sheet 35 apparently covers a region where the reflection sheet 12 is not provided. Thereby, in the contact part of the light-guide plate 13 and the top flat surface 31, the coupling efficiency from LED23 to the light-guide plate 13 can be improved, and light utilization efficiency can be improved. Therefore, the light extraction efficiency can be made uniform between the region where the reflection sheet 12 is formed and the region where the reflection sheet 12 is not formed. Therefore, the luminance uniformity of the light source module can be improved.

  Further, as shown in FIG. 3, the light source module of the present embodiment includes a plurality of LEDs 23 a and 23 b as light sources, and the LEDs 23 a and 23 b are provided in two rows along the longitudinal direction of the optical coupling member 30. The optical coupling member 30 has a cross-section perpendicular to the arrangement direction of the LEDs 23a and 23b in an arc shape or an arc shape that connects the LEDs 23a and 23b arranged in the two rows.

  In this configuration, the cross section in the longitudinal direction of the optical coupling member 30 is a dome shape. The LEDs 23 a and 23 b are arranged at both ends of the lower surface of the optical coupling member 30 in a cross section perpendicular to the longitudinal direction of the optical coupling member 30. Therefore, the luminance distribution can be made uniform in the light guide plate 13.

  In the present embodiment, the light source module 20 is provided with two rows of LEDs 23a and 23b. However, the present invention is not necessarily limited to this. For example, as shown in FIGS. 13A and 13B, it is possible to use an optical coupling member 40 (one-row arrangement LED) only on one side.

  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.

1 Liquid crystal display device (electronic equipment)
12 Reflective sheet (second reflective member)
13 Light guide plate 20 Light source module 23 LED (light source)
23a, 23b LED (light source)
23a / 23b LED (light source)
30 Optical coupling member 31 Flat top surface (optical coupling portion)
33 Flat bottom surface (lower surface of optical coupling member)
34a Flat surface 35 Reflective sheet (first reflective member)
40 Optical coupling member

Claims (7)

A light guide plate;
A light source provided below the light guide plate;
An optical coupling member that is provided between the light source and the light guide plate, and couples the light so that the light from the light source guides the inside of the light guide plate;
The light source is disposed on the lower surface of the optical coupling member,
The optical coupling member has an optical coupling portion with a light guide plate on an upper surface, a concave portion is formed on the lower surface so as to avoid the light source and include at least a part below the optical coupling portion,
The light source module according to claim 1, further comprising: a first reflection member that reflects the light returned to the light coupling member without being optically coupled to the light guide plate to the light guide plate. The optical coupling member has a top flat surface that abuts the lower surface of the light guide plate in a plane,
2. The light guide plate according to claim 1, further comprising a second reflection member provided on a lower surface of the light guide plate so as to avoid a contact portion with the top flat surface and reflecting light guided through the light guide plate. The light source module according to 1. The concave portion has a flat surface parallel to the optical coupling portion,
The light source module according to claim 1, wherein the first reflecting member is provided on the flat surface.   The light source module according to claim 3, wherein the flat surface is parallel to a lower surface of the light guide plate.   3. The first reflecting member according to claim 2, wherein a width of a cross section in a direction perpendicular to a longitudinal direction of the optical coupling member is larger than a width of the top flat surface in the same direction. The light source module described. The light source comprises a plurality of LEDs,
The LEDs are provided in two rows along the longitudinal direction of the optical coupling member,
6. The optical coupling member according to claim 1, wherein a cross section in a direction perpendicular to an arrangement direction of the LEDs is an arc shape or an arc shape connecting the LEDs arranged in the two rows. The light source module according to any one of claims. The electronic device provided with the light source module of any one of Claims 1-6.

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