JP2009134903A - Plane light emitting apparatus, display device, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plane light emitting apparatus which can improve a light utilization efficiency and can make its thickness thinner. <P>SOLUTION: The plane light emitting apparatus 20 is provided with a light guide plate 21 having a light emitting surface 21a, LED chips 23 which have a main light emitting surface 23a crossing almost perpendicularly with a thickness direction of the light guide plate 21 and is arranged inside the light guide plate 21, a reflection portion 25a which is arranged at a position facing the main light emitting surface 23a of the LED chip 23 and has reflection surfaces 25c and 25d inclined against the main light emitting surface 23a of the LED chip 23 and reflects light from the LED chip 23 in a direction A, and a reflection portion 25b which is arranged on a side of the direction A of the reflection portion 25a and has reflection surfaces 25f and 25g inclined against a surface almost perpendicular to the direction A and moreover reflects the light from the reflection portion 25a to the inside of the light guide plate 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a surface light-emitting device, a display device, and an electronic device, and more particularly to a surface light-emitting device, a display device, and an electronic device including a light source and a light guide plate.

  Conventionally, a surface light-emitting device that includes a light source and a light guide plate and functions as a backlight of a liquid crystal display device is known.

  FIG. 13 is a cross-sectional view illustrating the structure of a conventional surface light emitting device. In the conventional surface light emitting device 100, as shown in FIG. 13, the light guide plate 101 having the light exit surface 101 a, the reflection sheet 102 disposed on the back surface 101 b side of the light guide plate 101, and the edge of the light guide plate 101. , A package 104 that houses the light source 103, and an FPC (Flexible Printed Circuit) 105 on which the package 104 is mounted. A liquid crystal display panel 110 is disposed on the light exit surface 101 a side of the light guide plate 101.

  In the conventional surface light emitting device 100, the light guide plate 101 has a thickness of about 0.4 mm to about 0.6 mm. The light source 103 has a main light emitting surface 103 a that extends parallel to the thickness direction of the light guide plate 101. Then, the light emitted from the main light emitting surface 103 a of the light source 103 travels toward the inside of the light guide plate 101.

  In the conventional surface light emitting device 100, as described above, the light source 103 is arranged so that the main light emitting surface 103a extends in parallel with the thickness direction of the light guide plate 101. It is necessary to increase the thickness of the light guide plate 101 according to the height of the package 104. For this reason, there is an inconvenience that it is difficult to reduce the thickness of the surface light emitting device 100.

  In order to eliminate this inconvenience, there has been proposed a surface light emitting device in which a light source is arranged inside a light guide plate and a main light emitting surface of the light source is arranged so as to be substantially orthogonal to the thickness direction of the light guide plate (for example, a patent). Reference 1).

  FIG. 14 is a cross-sectional view showing the structure of the surface light emitting device disclosed in Patent Document 1. 15 is a cross-sectional view taken along arrow D in FIG. In Patent Document 1, as shown in FIG. 14, a light guide plate 201 having a light emission surface 201 a and a back surface 201 b, and a light emitting element (light source) 202 disposed inside the edge of the light guide plate 201 on the back surface 201 b side. A surface light emitting device 200 including a flexible substrate 203 on which the light emitting element 202 is mounted and a reflection sheet 204 disposed on the light emitting surface 201a side of the edge of the light guide plate 201 is disclosed. Further, a liquid crystal display panel 210 is disposed on the light exit surface 201 a side of the light guide plate 201.

  In the surface light emitting device 200, the light emitting element 202 has a main light emitting surface 202 a that is substantially orthogonal to the thickness direction of the light guide plate 201. The reflection sheet 204 is disposed in parallel to the main light emitting surface 202 a of the light emitting element 202 at a position facing the main light emitting surface 202 a of the light emitting element 202. And the light radiate | emitted from the main light emission surface 202a of the light emitting element 202 advances to the reflective sheet 204 side.

In the surface light emitting device 200 of Patent Document 1, the light emitting element 202 is disposed inside the edge portion of the light guide plate 201, and the main light emitting surface 202 a of the light emitting element 202 is substantially orthogonal to the thickness direction of the light guide plate 201. Therefore, when the main light emitting surface 202a of the light emitting element 202 is arranged so as to be parallel to the thickness direction of the light guide plate 201, the main light emitting surface 202a of the light emitting element 202 is substantially the same as the thickness direction of the light guide plate 201. Compared with the case where the light emitting element 202 is disposed outside the light emitting surface 201a side or the back surface 201b side of the light guide plate 201 in the orthogonal state, the surface light emitting device 200 can be made thinner.
JP 2001-67917 A

  However, in the surface light-emitting device 200 of Patent Document 1, the reflection sheet 204 is disposed in parallel with the main light-emitting surface 202a of the light-emitting element (light source) 202. Therefore, as shown in FIG. Light (P101) emitted from the light emitting surface 202a substantially vertically is reflected by the reflection sheet 204 and travels toward the main light emitting surface 202a of the light emitting element 202 and the flexible substrate 203. For this reason, the light emitted substantially perpendicularly from the main light emitting surface 202 a of the light emitting element 202 is absorbed by the main light emitting surface 202 a of the light emitting element 202 and the flexible substrate 203.

  Further, light (P102) emitted from the main light emitting surface 202a of the light emitting element 202 with an inclination in the A direction is repeatedly reflected by the reflective sheet 204 and the flexible substrate 203 at the edge of the light guide plate 201 to the side surface of the light guide plate 201. It reaches and leaks (emits) from the side surface of the light guide plate 201 to the outside.

  As described above, the surface light emitting device 200 of Patent Document 1 has a problem that it is difficult to improve the utilization efficiency of light emitted from the light emitting element 202.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to improve the light use efficiency and reduce the thickness of the surface light emitting device, the display device, and the electronic device. Is to provide equipment.

  In order to achieve the above object, a surface light emitting device according to a first aspect of the present invention includes a light guide plate having a light output surface, a main light emitting surface substantially orthogonal to the thickness direction of the light guide plate, and an interior of the light guide plate. A light source that is at least partially disposed on the light source, a first reflection surface that is disposed at a position facing the main light emitting surface of the light source, and that is inclined with respect to the main light emitting surface of the light source, and light from the light source A first reflecting member that reflects the first reflecting member in a first direction along the edge of the light guide plate, and a surface that is disposed on the side of the first reflecting member in the first direction and substantially orthogonal to the first direction. And a second reflecting member that has a second reflecting surface inclined with respect to the first reflecting member and reflects light from the first reflecting member to the inside of the light guide plate.

  In the surface light emitting device according to the first aspect, as described above, the surface light emitting device is disposed at a position facing the main light emitting surface of the light source, has a first reflecting surface inclined with respect to the main light emitting surface of the light source, and A first reflecting member that reflects light from the light source in a first direction along the edge of the light guide plate; and a first direction of the first reflecting member that is disposed on the side of the first direction; A second reflecting member that has a second reflecting surface that is inclined with respect to a substantially orthogonal surface and that reflects light from the first reflecting member to the inside of the light guide plate. By comprising in this way, the light radiate | emitted substantially perpendicularly from the main light emission surface of the light source can be advanced in a 1st direction by reflecting with the 1st reflective surface of a 1st reflective member. Then, the light that has traveled in the first direction by the first reflecting member and the light that is emitted from the main light emitting surface of the light source with an inclination in the first direction are reflected by the second reflecting surface of the second reflecting member. , It can be advanced inside the light guide plate. Thereby, light emitted from the main light emitting surface of the light source substantially perpendicularly or light emitted from the main light emitting surface of the light source with an inclination in the first direction is absorbed by the main light emitting surface of the light source or the side surface of the light guide plate. It is possible to suppress leakage (outgoing) from the outside to the outside. As a result, the utilization efficiency of light emitted from the light source can be improved.

  In the surface light emitting device according to the first aspect, as described above, by providing a light source having a main light emitting surface substantially orthogonal to the thickness direction of the light guide plate and at least a part of which is disposed inside the light guide plate. In the case where the main light emitting surface of the light source is arranged so as to be parallel to the thickness direction of the light guide plate, or the light emitting surface of the light guide plate with the main light emitting surface of the light source substantially orthogonal to the thickness direction of the light guide plate The surface light emitting device can be made thinner as compared with the case where it is arranged outside the side or the back side.

In the surface light emitting device according to the first aspect described above, preferably, when the inclination angle of the first reflecting surface of the first reflecting member with respect to the main light emitting surface of the light source is θ ₁ and the refractive index of the light guide plate is n, {180− arcsin (1 / n)} / 2> θ ₁ > {arcsin (1 / n)} / 2 is satisfied. If comprised in this way, if the light source is arrange | positioned at the light-projection surface side of a light-guide plate and the 1st reflection member is arrange | positioned at the back side of a light-guide plate, for example, it will be substantially perpendicular from the main light emission surface of a light source. The light emitted to the light travels as follows. Specifically, when θ ₁ <45 °, the light emitted substantially perpendicularly from the main light emitting surface of the light source is reflected by the first reflecting surface of the first reflecting unit, and is incident on the light guide plate at an incident angle of 2θ _1. It advances (incidents) toward the light exit surface. When the incident angle 2θ ₁ satisfies the relationship 2θ ₁ > arcsin (1 / n) (the relationship θ ₁ > {arcsin (1 / n)} / 2), the light is emitted substantially perpendicularly from the main light emitting surface of the light source. The transmitted light travels in the first direction while repeating total reflection on the light emitting surface and the back surface of the light guide plate. On the other hand, when θ ₁ > 45 °, the light emitted substantially perpendicularly from the main light emitting surface of the light source is reflected by the first reflecting surface of the first reflecting portion and guided at an incident angle of 180 ° −2θ _1. Progress (incident) toward the back of the light plate. When the incident angle 180 ° −2θ ₁ satisfies the relationship of 180 ° −2θ ₁ > arcsin (1 / n) (the relationship of {180−arcsin (1 / n)} / 2> θ ₁ ), The light emitted substantially perpendicularly from the main light emitting surface travels in the first direction while repeating total reflection on the back surface of the light guide plate and the light emitting surface. Thus, the light emitted substantially perpendicularly from the main light emitting surface of the light source can be advanced in the first direction while being totally reflected. Thereby, light emitted substantially perpendicularly from the main light emitting surface of the light source can be prevented from leaking (emitted) outward from the main light emitting surface and the back surface of the light guide plate at the edge of the light guide plate. The utilization efficiency of the light emitted from the light can be further improved. In addition, since light emitted from the main light emitting surface of the light source substantially vertically leaks (emits) to the outside from the main light emitting surface and the back surface of the light guide plate at the edge of the light guide plate, the light guide plate can be suppressed. Since it can suppress that the brightness | luminance of the part periphery of this edge part becomes larger than the brightness | luminance of parts other than the edge periphery of a light-guide plate, the uniformity of a brightness | luminance can be improved.

In the surface light-emitting device according to the first aspect, preferably, an inclination angle of the second reflecting member with respect to a surface substantially orthogonal to the first direction of the second reflecting surface is θ ₂ and a refractive index of the light guide plate is n. , {180−arcsin (1 / n)} / 2> θ ₂ > {arcsin (1 / n)} / 2. If comprised in this way, if the light reflected by the 1st reflective member will advance from the one side of the 1st direction to the other side, for example, the light reflected by the 2nd reflective member will advance as follows. To do. Specifically, in the case of θ ₂ <45 °, the light reflected by the second reflecting member is reflected by the second reflecting surface of the second reflecting portion and is incident on the one side surface of the light guide plate at an incident angle of 2θ _2. Travel (incident) toward When the incident angle 2θ ₂ satisfies the relationship 2θ ₂ > arcsin (1 / n) (the relationship θ ₂ > {arcsin (1 / n)} / 2), the light reflected by the second reflecting member is The light advances toward the inside of the light guide plate while repeating total reflection on one side and the other side of the light guide plate. On the other hand, in the case of θ ₂ > 45 °, the light reflected by the second reflecting member is reflected by the second reflecting surface of the second reflecting portion and has an incident angle of 180 ° −2θ ₂ at the other angle of the light guide plate. Progress (incident) toward the side. The incident angle 180 ° −2θ ₂ satisfies the relationship of 180 ° −2θ ₂ > arcsin (1 / n) (relationship of {180−arcsin (1 / n)} / 2> θ ₂ ), so that the second The light reflected by the reflecting member travels inside the light guide plate while repeating total reflection on the other side surface and one side surface of the light guide plate. In this way, the light reflected by the second reflecting member can be advanced inside the light guide plate while being totally reflected. Accordingly, it is possible to suppress light reflected by the second reflecting member from leaking (emitted) to the outside from the side surfaces (one side surface and the other side surface) of the light guide plate at the edge of the light guide plate. The utilization efficiency of the light emitted from the light can be further improved.

  In the surface light emitting device according to the first aspect described above, preferably, the first reflecting surface of the first reflecting member includes a pair of reflecting surfaces that respectively reflect light from the light source to one side and the other side in the first direction. . If comprised in this way, a pair of reflective surface can be arrange | positioned in the bent state. Thereby, compared with the case where the 1st reflective surface of a 1st reflective member is comprised by the single reflective surface which reflects the light from a light source in the 1st direction, for example only to one side, the thickness of a 1st reflective member Can be reduced. As a result, the surface light emitting device can be thinned. Moreover, the 1st reflective surface of a 1st reflective member is comprised by a pair of reflective surface which reflects the light from a light source on the one side and the other side of a 1st direction, respectively, and the light from a light source is 1st. It can be made to advance in the state disperse | distributed to the one side and other side of this direction. Thereby, the uniformity of luminance can be improved.

  In the surface light emitting device in which the first reflecting surface of the first reflecting member includes a pair of reflecting surfaces, preferably, the first reflecting member has an intersection line of the pair of reflecting surfaces in the first direction of the main light emitting surface of the light source. It is arranged to face the center. If comprised in this way, since the light radiate | emitted from the main light emission surface of the light source can be equally reflected on the one side and the other side in the first direction by the pair of reflection surfaces, the luminance uniformity is further improved. Can be improved.

  In the surface light emitting device according to the first aspect described above, preferably, the light guide plate has a back surface disposed to face the light emitting surface, and at least a part of the first reflecting member and at least a part of the second reflecting member. Is disposed between the light exit surface and the back surface of the light guide plate. If comprised in this way, a surface emitting device can be made thinner.

  In the surface light emitting device according to the first aspect, preferably, the light source, the first reflecting member, and the second reflecting member are integrally provided on the light guide plate by thermal fusion. If comprised in this way, at least one part of a light source, at least one part of a 1st reflective member, and at least one part of a 2nd reflective member can be easily made into the inside of a light-guide plate (between a light-emitting surface and a back surface). ), The surface light emitting device can be easily reduced in thickness.

  In the surface light emitting device according to the first aspect described above, preferably, the light guide plate has a back surface disposed opposite to the light output surface, and light reflected by the second reflecting member is output to the back surface of the light guide plate. A convex portion or a concave portion that is guided to the surface side and is emitted outward from the light emitting surface is formed. If comprised in this way, since the light reflected by the 2nd reflective member can be easily radiate | emitted outside from the light-projection surface of a light-guide plate, the utilization efficiency of the light radiate | emitted from a light source is easy, Can be improved.

  In the surface light emitting device according to the first aspect, the light guide plate is preferably made of a transparent or translucent resin. If comprised in this way, it can suppress that the light radiate | emitted from the light source is absorbed in the inside of a light-guide plate, Therefore The utilization efficiency of the light radiate | emitted from a light source can be improved more.

  A display device according to a second aspect of the present invention includes the surface light-emitting device according to any one of claims 1 to 9 and a display panel illuminated by the surface light-emitting device. If comprised in this way, while improving the utilization efficiency of light, the display apparatus which can be reduced in thickness can be obtained.

  An electronic apparatus according to a third aspect of the present invention comprises the display device according to claim 10. If comprised in this way, while improving the utilization efficiency of light, the electronic device which can be reduced in thickness can be obtained.

  As described above, according to the present invention, it is possible to easily obtain a surface light emitting device, a display device, and an electronic device that can improve the light use efficiency and can be thinned.

  FIG. 1 is a front view showing an overall configuration of a mobile phone including a surface light emitting device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a structure of a liquid crystal display device including a surface light emitting device according to an embodiment of the present invention. 3-12 is a figure for demonstrating the detailed structure of the surface emitting device shown in FIG. With reference to FIGS. 1-12, the structure of the mobile telephone 1 provided with the surface emitting device 20 by one Embodiment of this invention is demonstrated.

  As shown in FIG. 1, a mobile phone 1 including a surface light emitting device 20 according to an embodiment of the present invention includes a liquid crystal display device 10 including the surface light emitting device 20, and an upper housing 2 that houses the liquid crystal display device 10. The lower housing 3 and the hinge portion 4 disposed between the upper housing 2 and the lower housing 3 are provided. The hinge portion 4 allows the mobile phone 1 to be folded. The upper housing 2 is provided with a receiving speaker 6. The lower housing 3 is provided with a plurality of operation buttons 7 and a microphone 8 for transmission. The mobile phone 1 is an example of the “electronic device” of the present invention, and the liquid crystal display device 10 is an example of the “display device” of the present invention.

  As shown in FIG. 2, the liquid crystal display device 10 includes liquid crystal display panels 11a and 11b, polarizing plates 12a and 12b sandwiching the liquid crystal display panels 11a and 11b, and lenses disposed on the back side of the liquid crystal display panels 11a and 11b. The sheet 13 and the diffusion sheet 14, and the surface light emitting device 20 that is disposed on the back side of the diffusion sheet 14 and functions as a backlight are configured. The liquid crystal display panels 11a and 11b are examples of the “display panel” in the present invention.

  The surface light emitting device 20 includes a light guide plate 21, a reflection sheet 22, a plurality of LED chips 23, an FPC 24, and a reflection member 25. The LED chip 23 is an example of the “light source” in the present invention.

  The light guide plate 21 is formed with a thickness of about 0.1 mm to about 0.3 mm, and is made of an acrylic resin that is transparent and has excellent light transmittance. In addition, as long as the light-guide plate 21 is a material excellent in light transmittance and moldability, it is also possible to use materials other than acrylic resin, such as polycarbonate.

  The light guide plate 21 includes a light emitting surface 21a that emits light from the LED chip 23 toward the liquid crystal display panels 11a and 11b, a back surface 21b disposed to face the light emitting surface 21a, and one of the A directions (see FIG. 3). One side surface 21c (see FIG. 3) arranged on the side (arrow A1 direction side) and the other side surface 21d (see FIG. 3) arranged on the other side in the A direction (arrow A2 direction side). . The one side surface 21c and the other side surface 21d are examples of the “surface substantially orthogonal to the first direction” in the present invention.

  As shown in FIG. 2, a prism pattern 21e is formed on the back surface 21b. The prism pattern 21e guides light reflected by a reflecting portion 25b (to be described later) of the reflecting member 25 to the light emitting surface 21a side and emits the light to the outside from the light emitting surface 21a. ing. As shown in FIGS. 2 and 3, the prism pattern 21e is formed by a plurality of recesses 21f extending in the A direction. Specifically, as shown in FIG. 2, an inclined surface 21g inclined by a predetermined angle with respect to the back surface 21b is formed in the recess 21f. And the light reflected by the reflective part 25b etc. which are mentioned later of the reflecting member 25 is reflected by the inclined surface 21g of the concave part 21f, thereby being guided to the light emitting surface 21a side and emitted outward from the light emitting surface 21a. To do. The direction A is an example of the “first direction” in the present invention.

  The reflection sheet 22 is disposed on the back surface 21b side of the light guide plate 21 and has a function of reflecting light emitted from the back surface 21b of the light guide plate 21 to the light guide plate 21 side.

  The plurality of LED chips 23 and the FPC 24 are arranged on the light emitting surface 21 a side of the edge portion of the light guide plate 21, and the reflecting member 25 is arranged on the back surface 21 b side of the edge portion of the light guide plate 21.

  Moreover, the several LED chip 23 is arrange | positioned at predetermined intervals in the A direction (direction along the edge part of the light-guide plate 21), as shown in FIG. Further, as shown in FIG. 2, the plurality of LED chips 23 are mounted on a film-like FPC in which a conductive pattern (not shown) is formed. Specifically, the LED chip 23 has an electrode (not shown) bonded directly to a conductive pattern (not shown) of the FPC 24. That is, the LED chip 23 is flip-chip bonded to the FPC 24. The electrical connection between the LED chip 23 and the FPC 24 may be performed by wire bonding using an Au wire or the like. A phosphor (not shown) is applied on the main light emitting surface 23a of the LED chip 23. This phosphor may not be applied to the main light emitting surface 23a of the LED chip 23 but may be contained in the diffusion sheet 14 or the like.

  In the present embodiment, the plurality of LED chips 23, the FPC 24, and the reflecting member 25 are integrally provided on the light guide plate 21 by heat sealing. Specifically, the light guide plate 21 is formed with a depression in a portion where the LED chip 23 and a later-described reflecting portion 25a of the reflecting member 25 are disposed by hot pressing. Then, the FPC 24 on which the LED chip 23 is mounted and the reflection member 25 are superposed on the light guide plate 21, and the light guide plate 21, the plurality of LED chips 23, the FPC 24, and the reflection member 25 are heat-sealed by hot pressing. Let Accordingly, the plurality of LED chips 23, the FPC 24, and the reflection member 25 are integrally provided on the light guide plate 21.

  The LED chip 23 is disposed between the light emitting surface 21 a and the back surface 21 b of the light guide plate 21. That is, the entire LED chip 23 is embedded in the light guide plate 21.

  In the present embodiment, the LED chip 23 is disposed such that the main light emitting surface 23 a is substantially parallel to the light emitting surface 21 a and the back surface 21 b of the light guide plate 21. That is, the LED chip 23 is disposed so that the main light emitting surface 23 a is substantially orthogonal to the thickness direction of the light guide plate 21.

  In the present embodiment, the reflecting member 25 is disposed between the light emitting surface 21 a and the back surface 21 b of the light guide plate 21.

  Here, in this embodiment, as shown in FIGS. 4 and 5, the reflecting member 25 is disposed at a position facing the main light emitting surface 23a (see FIG. 2) of the plurality of LED chips 23 (see FIG. 4). The plurality of reflecting portions 25a and the plurality of reflecting portions 25b arranged on the sides in the A direction of the plurality of reflecting portions 25a. The reflective portion 25a is an example of the “first reflective member” in the present invention, and the reflective portion 25b is an example of the “second reflective member” in the present invention.

  In this embodiment, as shown in FIGS. 5 and 6, the reflecting portion 25 a has a pair of isosceles triangles and a pair of opposingly disposed main light emitting surfaces 23 a of the LED chip 23 (see FIG. 6). Reflecting surfaces 25c and 25d are included. Thus, the reflecting surfaces 25c and 25d are arranged in a bent state. The pair of reflecting surfaces 25c and 25d is an example of the “first reflecting surface” and the “pair of reflecting surfaces” in the present invention.

  Further, as shown in FIG. 8, the length L1 of the pair of reflecting surfaces 25c and 25d in the B direction (direction orthogonal to the A direction) is larger than the length L2 of the LED chip 23 in the B direction. Further, the length L3 in the A direction in which the pair of reflecting surfaces 25c and 25d are combined is larger than the length L4 in the A direction of the LED chip 23.

  In addition, as shown in FIG. 6, the reflection portion 25 a has an intersection line (an isosceles triangular apex) 25 e between a pair of reflection surfaces 25 c and 25 d facing the center in the A direction of the main light emitting surface 23 a of the LED chip 23. Are arranged to be.

  The pair of reflecting surfaces 25 c and 25 d are inclined with respect to the main light emitting surface 23 a of the LED chip 23 and the back surface 21 b of the light guide plate 21. Specifically, the reflecting surface 25c is inclined so as to approach the back surface 21b of the light guide plate 21 toward the one side in the A direction (arrow A1 direction side). The reflecting surface 25c has a function of reflecting light (P1) emitted substantially perpendicularly from the main light emitting surface 23a of the LED chip 23 to one side in the A direction (arrow A direction side). Further, the reflection surface 25d is inclined so as to approach the back surface 21b of the light guide plate 21 toward the other side in the A direction (arrow A2 direction side). The reflection surface 25d has a function of reflecting light (P1) emitted substantially perpendicularly from the main light emitting surface 23a of the LED chip 23 to the other side in the A direction (arrow A2 direction side).

  In this manner, the pair of reflecting surfaces 25c and 25d are arranged in a bent state, and light from the main light emitting surface 23a of the LED chip 23 is directed to the arrow A1 direction side and the arrow A2 direction by the pair of reflecting surfaces 25c and 25d. For example, as shown in FIG. 12, the reflecting portion 25h is formed by one reflecting surface 25i that reflects the light (P11) from the LED chip 23 only on the arrow A1 direction side. Compared to the case, the thickness of the reflecting portion 25a can be reduced.

In the present embodiment, as shown in FIG. 6, the pair of reflection surfaces 25c and 25d are inclined with respect to the light emitting surface 21a and the back surface 21b of the light guide plate 21 (inclination angle with respect to the main light emitting surface 23a of the LED chip 23). Is θ ₁ and the refractive index of the light guide plate 21 is n, it is formed so as to satisfy the relationship of {180−arcsin (1 / n)} / 2> θ ₁ > {arcsin (1 / n)} / 2. ing.

Specifically, when θ ₁ <45 °, the light (P1) emitted from the main light emitting surface 23a of the LED chip 23 substantially perpendicularly is reflected by the reflecting surfaces 25c and 25d, and α ₁ (= 2θ ₁ ). Travels (incidents) toward the light exit surface 21a of the light guide plate 21 at an incident angle of. The incident angle α ₁ (= 2θ ₁ ) satisfies the relationship α ₁ (= 2θ ₁ )> arcsin (1 / n) (the relationship θ ₁ > {arcsin (1 / n)} / 2). The light (P1) emitted substantially perpendicularly from the main light emitting surface 23a of the LED chip 23 repeats total reflection on the light emitting surface 21a and the back surface 21b of the light guide plate 21, while one side in the A direction (arrow A1 direction side) or Proceed to the other side (arrow A2 direction side).

On the other hand, when θ ₁ > 45 °, as shown in FIG. 7, the light (P2) emitted substantially perpendicularly from the main light emitting surface 23a of the LED chip 23 is reflected by the reflecting surfaces 25c and 25d, and α ₂ It advances (incidents) toward the rear surface 21b of the light guide plate 21 at an incident angle of (= 180 ° −2θ ₁ ). This incident angle α ₂ (= 180 ° −2θ ₁ ) is α ₂ (= 180 ° −2θ ₁ )> arcsin (1 / n) ({180−arcsin (1 / n)} / 2> θ ₁ The light (P2) emitted substantially perpendicularly from the main light emitting surface 23a of the LED chip 23 repeats total reflection on the back surface 21b and the light emitting surface 21a of the light guide plate 21 and satisfies one of the A directions. Proceed to the side or the other side.

When the refractive index n of the light guide plate 21 is 1.49, for example, the inclination angle θ ₁ may satisfy the relationship of 68.92 °> θ ₁ > 21.08 °. Further, as the inclination angle θ ₁ decreases, the height (thickness) of the reflecting portion 25a decreases, and the light guide plate 21 can be made thinner. For this reason, it is desirable that the inclination angle θ ₁ is about 21.1 °.

  On the other hand, the reflection part 25b includes a pair of reflection surfaces 25f and 25g arranged on the side in the A direction of the reflection part 25a, as shown in FIGS. The reflective surfaces 25f and 25g are examples of the “second reflective surface” in the present invention.

  The pair of reflecting surfaces 25f and 25g are inclined with respect to a surface (eg, one side surface 21c or the other side surface 21d (see FIG. 3) of the light guide plate 21) that is substantially orthogonal to the A direction. Specifically, as illustrated in FIG. 8, the reflection surface 25 f is inclined so as to approach the one side surface 21 c of the light guide plate 21 in the direction of the arrow B <b> 1. The reflecting surface 25f has a function of reflecting the light (P3) reflected by the reflecting surface 25c of the reflecting portion 25a to the inner side (arrow B1 direction side) of the light guide plate 21. Similarly, the reflecting surface 25g is inclined so as to approach the other side surface 21d (see FIG. 3) of the light guide plate 21 in the direction of the arrow B1. The reflecting surface 25g has a function of reflecting the light reflected by the reflecting surface 25d of the reflecting portion 25a to the inside of the light guide plate 21 (arrow B2 direction side).

Further, in the present embodiment, the pair of reflecting surfaces 25f and 25 g, A direction substantially perpendicular to the plane (e.g., first side surface 21c and the other side surface 21d of the light guide plate 21) of the inclination angle with respect to the theta _2, the light guide plate 21 When the refractive index is n, it is formed so as to satisfy the relationship of {180−arcsin (1 / n)} / 2> θ ₂ > {arcsin (1 / n)} / 2.

Specifically, when θ ₂ > 45 °, the light (P3) reflected by the reflecting surface 25c of the reflecting portion 25a is reflected by the reflecting surface 25f of the reflecting portion 25b, and α ₃ (= 180 ° −2θ ₂ ) It advances (incidents) toward the one side surface 21c of the light guide plate 21 at an incident angle of ₂ ). This incident angle α ₃ (= 180 ° −2θ ₂ ) is α ₃ (= 180 ° −2θ ₂ )> arcsin (1 / n) ({180−arcsin (1 / n)} / 2> θ ₂ In other words, the light (P3) reflected by the reflecting surface 25c of the reflecting portion 25a repeats total reflection on the one side surface 21c and the other side surface 21d of the light guide plate 21, while the inner side of the light guide plate 21 (arrow B1 direction side). Similarly, the light reflected by the reflecting surface 25d of the reflecting portion 25a also proceeds to the inner side (arrow B1 direction side) of the light guide plate 21 while repeating total reflection.

On the other hand, when θ ₂ <45 °, as shown in FIG. 9, the light (P4) reflected by the reflecting surface 25c of the reflecting portion 25a has an incident angle of α ₄ (= 2θ ₂ ) and has a light guide plate 21. It advances (incidents) toward the other side surface 21d. When the incident angle α ₄ (= 2θ ₂ ) satisfies the relationship α ₄ (= 2θ ₂ )> arcsin (1 / n) (the relationship θ ₂ > {arcsin (1 / n)} / 2), The light (P4) reflected by the reflecting surface 25c of the reflecting portion 25a proceeds to the inside of the light guide plate 21 (arrow B1 direction side) while repeating total reflection on the other side surface 21d and one side surface 21c of the light guide plate 21. Similarly, the light reflected by the reflecting surface 25d of the reflecting portion 25a also proceeds to the inner side (arrow B1 direction side) of the light guide plate 21 while repeating total reflection.

When the refractive index n of the light guide plate 21 is 1.49, for example, the inclination angle θ ₂ may satisfy the relationship of 68.92 °> θ ₁ > 21.08 °. Here, when the inclination angle θ ₂ is θ ₂ > 45 °, the light reflected by the reflecting portion 25b proceeds to spread. On the other hand, when the inclination angle θ ₂ is θ ₂ <45 °, the light reflected by the reflecting portion 25b proceeds so as to be narrowed down. For this reason, when θ ₂ <45 °, as shown in FIG. 10, the difference in luminance between the bright part (Q1) and the dark part (Q2) becomes large, so the inclination angle θ ₂ is larger than 45 °. Is preferable. When the tilt angle θ ₂ is larger than 45 °, the greater the tilt angle θ ₂ , the more uniform the brightness can be. Therefore, the tilt angle θ ₂ is about 68.9 °. It is more desirable.

In addition, by making the inclination angle θ ₂ larger than 45 ° (about 68.9 °), it is possible to reduce the length in the B direction of the reflecting portion 25b (reflecting member 25). The surface light emitting device 20 can be reduced in size.

  Further, the light that has been reflected by the reflecting portions 25a and 25b and traveled inside the light guide plate 21 is caused by the concave portions 21f of the prism pattern 21e formed on the back surface 21b of the light guide plate 21, as shown in FIG. While being guided to the light emitting surface 21a side, the light is emitted from the light emitting surface 21a to the liquid crystal display panels 11a and 11b (see FIG. 2) side.

  In the above description, the light emitted substantially perpendicularly from the main light emitting surface 23a of the LED chip 23 is reflected by the reflecting portions 25a and 25b and proceeds to the inside of the light guide plate 21. Similarly, the light emitted from the main light emitting surface 23a with an inclination in the A direction is reflected by the reflecting portions 25a and 25b and proceeds to the inside of the light guide plate 21. The light emitted from the main light emitting surface 23a of the LED chip 23 with an inclination in the A direction is reflected by the reflection sheet 22 or the prism pattern 21e on the back surface 21b of the light guide plate 21 to emit light from the light guide plate 21. The light is guided to the surface 21a side and is emitted from the light emitting surface 21a to the liquid crystal display panels 11a and 11b side.

  In the present embodiment, as described above, the reflecting portion 25a is provided with the reflecting surfaces 25c and 25d inclined with respect to the main light emitting surface 23a of the LED chip 23 at a position facing the main light emitting surface 23a of the LED chip 23, The light from the LED chip 23 is reflected in the A direction (the direction along the edge of the light guide plate 21) by the reflecting portion 25a (reflecting surfaces 25c and 25d), and the reflecting portion 25b reflects the A of the reflecting portion 25a. Reflective surfaces 25f and 25g that are inclined with respect to a surface substantially orthogonal to the A direction (for example, the one side surface 21c and the other side surface 21d of the light guide plate 21) are provided on the side of the direction, and the light from the reflecting portion 25a is reflected. The light is reflected on the inner side of the light guide plate 21 by the portion 25b (reflecting surfaces 25f and 25g). With this configuration, the light emitted substantially perpendicularly from the main light emitting surface 23a of the LED chip 23 can be advanced in the A direction by being reflected by the reflecting surfaces 25c and 25d of the reflecting portion 25a. Then, the light traveling in the A direction by the reflecting portion 25a and the light emitted from the main light emitting surface 23a of the LED chip 23 with an inclination in the A direction are reflected by the reflecting surfaces 25f and 25g of the reflecting portion 25b, thereby guiding the light. It can be advanced to the inside of the optical plate 21 (arrow B1 direction side). Thereby, the light emitted from the main light emitting surface 23a of the LED chip 23 substantially perpendicularly or the light emitted from the main light emitting surface 23a of the LED chip 23 with an inclination in the A direction is absorbed by the main light emitting surface 23a of the LED chip 23 and the like. Or leaking out (emits) from the one side surface 21c and the other side surface 21d of the light guide plate 21 can be suppressed. As a result, the utilization efficiency of the light emitted from the LED chip 23 can be improved.

  In the present embodiment, the main light emitting surface 23 a of the LED chip 23 is provided by providing the LED chip 23 having the main light emitting surface 23 a substantially orthogonal to the thickness direction of the light guide plate 21 and disposed inside the light guide plate 21. Is arranged so as to be parallel to the thickness direction of the light guide plate 21, or the LED chip 23 is emitted from the light guide plate 21 with the main light emitting surface 23 a of the LED chip 23 substantially orthogonal to the thickness direction of the light guide plate 21. The surface light emitting device 20 can be reduced in thickness as compared with the case where it is disposed outside the surface 21a side or the back surface 21b side.

Further, in the present embodiment, the theta ₁ (inclination angle with respect to the light exit surface 21a and rear surface 21b of the light guide plate 21) a pair of reflective surfaces 25c and 25d of the angle of inclination with respect to the main light emitting surface 23a of the LED chip 23, the light guide plate 21 When the refractive index is n, the LED is configured so as to satisfy the relationship of {180−arcsin (1 / n)} / 2> θ ₁ > {arcsin (1 / n)} / 2 as described above. The light emitted substantially perpendicularly from the main light emitting surface 23a of the chip 23 can be advanced in the A direction (arrow A1 direction side or arrow A2 direction side) while being totally reflected. Thereby, light emitted substantially perpendicularly from the main light emitting surface 23a of the LED chip 23 is prevented from leaking (emitted) to the outside from the main light emitting surface 23a and the back surface 21b of the light guide plate 21 at the edge of the light guide plate 21. Therefore, the utilization efficiency of the light emitted from the LED chip 23 can be further improved. Further, light emitted from the main light emitting surface 23 a of the LED chip 23 substantially vertically leaks (emits) to the outside from the main light emitting surface 23 a and the back surface 21 b of the light guide plate 21 at the edge of the light guide plate 21. As a result, it is possible to suppress the luminance of the portion around the edge of the light guide plate 21 from becoming higher than the luminance of the portion other than the periphery of the edge of the light guide plate 21, thereby improving the uniformity of the luminance. be able to.

Further, in the present embodiment, the angle of inclination with respect to the A direction substantially perpendicular to the plane of the reflecting surface 25f and 25 g (e.g., first side surface 21c and the other side surface 21d of the light guide plate 21) of the reflective portion 25b and theta _2, the light guide plate 21 Where n is a refractive index of {180-arcsin (1 / n)} / 2> θ ₂ > {arcsin (1 / n)} / 2. The light reflected by the reflecting portion 25b can be advanced to the inner side (arrow B1 direction side) of the light guide plate 21 while being totally reflected. Thereby, it is possible to suppress the light reflected by the reflecting portion 25b from leaking (emitted) to the outside from the one side surface 21c and the other side surface 21d of the light guide plate 21 at the edge portion of the light guide plate 21. The utilization efficiency of light emitted from the chip 23 can be further improved.

  In the present embodiment, the light from the LED chip 23 is provided by providing the reflecting portion 25a with a pair of reflecting surfaces 25c and 25d that reflect the light from the LED chip 23 toward the arrow A1 direction and the arrow A2 direction, respectively. Can be advanced in a state of being dispersed in the direction of arrow A1 or the direction of arrow A2. Thereby, the uniformity of luminance can be improved.

  In the present embodiment, the LED chip 23 is arranged by arranging the reflecting portion 25a so that the intersection line 25e of the pair of reflecting surfaces 25c and 25d faces the center of the main light emitting surface 23a of the LED chip 23 in the A direction. Since the light emitted from the main light emitting surface 23a can be reflected uniformly by the pair of reflecting surfaces 25c and 25d toward the arrow A1 direction side or the arrow A2 direction side, the luminance uniformity can be further improved. .

  In the present embodiment, the surface light-emitting device 20 can be made thinner by disposing the reflecting member 25 (reflecting portions 25 a and 25 b) between the light emitting surface 21 a and the back surface 21 b of the light guide plate 21. it can.

  In the present embodiment, the back surface 21b of the light guide plate 21 is provided with a concave portion 21f (prism pattern 21e) that guides the light reflected by the reflecting portion 25b or the like to the light emitting surface 21a side and emits the light to the outside from the light emitting surface 21a. By providing, the light reflected by the reflecting portion 25b and the like can be easily emitted outward from the light emitting surface 21a of the light guide plate 21, so that the utilization efficiency of the light emitted from the LED chip 23 can be easily achieved. Can be improved.

  Moreover, in this embodiment, since the light guide plate 21 is made of a transparent acrylic resin, the light emitted from the LED chip 23 can be suppressed from being absorbed inside the light guide plate 21. The utilization efficiency of the light emitted from 23 can be further improved.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the above-described embodiment, an example in which the present invention is applied to a mobile phone has been described. However, the present invention is not limited thereto, and may be applied to, for example, a liquid crystal television receiver other than the mobile phone.

  Moreover, although the reflection part 25a (1st reflection member) and the reflection part 25b (2nd reflection member) were shown about the example formed with the one reflection member 25 in the said embodiment, this invention is not limited to this. The first reflecting member and the second reflecting member may be provided separately.

Further, the reflection surfaces 25c and 25d may be formed so that the inclination angle θ ₁ is larger than 45 °, and the reflection surfaces 25f and 25g are formed so that the inclination angle θ ₂ is smaller than 45 °. May be.

  In the above embodiment, an example in which the entire LED chip is embedded in the light guide plate has been described. However, the present invention is not limited thereto, and at least a part of the LED chip is embedded in the light guide plate. That's fine.

  Moreover, in the said embodiment, although the example which comprised the reflection member so that the light from an LED chip might each reflect in the arrow A1 direction side and the arrow A2 direction side was shown, this invention is not limited to this, LED chip The reflecting member may be configured so that light from the light is reflected to either the arrow A1 direction side or the arrow A2 direction side.

  In the above-described embodiment, an example in which a prism pattern including concave portions is formed on the back surface of the light guide plate has been described. However, the present invention is not limited thereto, and a prism pattern including convex portions may be formed on the back surface of the light guide plate. Good. Moreover, it is also possible to form a convex part and a recessed part by embossing.

It is the front view which showed the whole structure of the mobile telephone provided with the surface emitting device by one Embodiment of this invention. 1 is a cross-sectional view illustrating a structure of a liquid crystal display device including a surface light emitting device according to an embodiment of the present invention. It is the top view which showed the structure of the light-guide plate and reflection member of the surface emitting device by one Embodiment of this invention shown in FIG. It is the perspective view which showed the structure of the light-guide plate and reflection member of the surface emitting device by one Embodiment of this invention shown in FIG. It is the perspective view which showed the structure of the reflection member of the surface emitting device by one Embodiment of this invention shown in FIG. FIG. 4 is a cross-sectional view in the direction of arrow C illustrating a state in which the inclination angle θ ₁ of the reflecting portion of the surface light emitting device according to the embodiment shown in FIG. 2 is smaller than 45 °. FIG. 3 is a cross-sectional view in the direction of arrow C illustrating a state in which an inclination angle θ ₁ of the reflecting portion of the surface light emitting device according to the embodiment shown in FIG. 2 is greater than 45 °. FIG. 3 is a plan view showing a state where an inclination angle θ ₂ of a reflecting portion of the surface light emitting device according to the embodiment of the present invention shown in FIG. 2 is larger than 45 °. FIG. 3 is a plan view showing a state where an inclination angle θ ₂ of a reflecting portion of the surface light emitting device according to the embodiment of the present invention shown in FIG. 2 is smaller than 45 °. FIG. 3 is a plan view showing a state where an inclination angle θ ₂ of a reflecting portion of the surface light emitting device according to the embodiment of the present invention shown in FIG. 2 is smaller than 45 °. It is sectional drawing which showed the state in which the light reflected by the reflection member of the surface emitting device by one Embodiment of this invention shown in FIG. 2 radiate | emits from the light-projection surface of a light-guide plate. FIG. 3 is a cross-sectional view in the direction of arrow C showing the structure of the reflecting member when light from the LED chip of the surface emitting device according to the embodiment of the present invention shown in FIG. 2 is reflected only in the direction of arrow A1. It is sectional drawing which showed the structure of the surface emitting apparatus by an example of the past. It is sectional drawing which showed the structure of the surface emitting apparatus disclosed by patent document 1. FIG. It is arrow sectional drawing of the arrow D direction of FIG.

Explanation of symbols

1 Mobile phone (electronic equipment)
10 Liquid crystal display device (display device)
11a, 11b Liquid crystal display panel (display panel)
20 surface light emitting device 21 light guide plate 21a light emitting surface 21b back surface 21c one side surface (surface substantially orthogonal to the first direction)
21d The other side (substantially orthogonal to the first direction)
21f Recess 23 LED chip (light source)
23a Main light emitting surface 25a, 25h Reflecting portion (first reflecting member)
25b Reflector (second reflecting member)
25c, 25d Reflective surface (first reflective surface, pair of reflective surfaces)
25e Intersection line 25f, 25g Reflective surface (second reflective surface)
25i reflective surface (first reflective surface)
θ ₁ , θ ₂ tilt angle

Claims (11)

A light guide plate having a light exit surface;
A light source having a main light emitting surface substantially orthogonal to the thickness direction of the light guide plate, and at least a part of which is disposed inside the light guide plate;
The light source is disposed at a position facing the main light emitting surface of the light source, has a first reflecting surface that is inclined with respect to the main light emitting surface of the light source, and emits light from the light source to an edge of the light guide plate A first reflecting member that reflects in a first direction along;
The first reflecting member has a second reflecting surface that is disposed on a side of the first reflecting member in the first direction and is inclined with respect to a surface that is substantially orthogonal to the first direction. A surface light emitting device comprising: a second reflecting member that reflects light from the inside to the inside of the light guide plate. When the inclination angle of the first reflecting surface of the first reflecting member with respect to the main light emitting surface of the light source is θ ₁ and the refractive index of the light guide plate is n,
{180-arcsin (1 / n)} / 2> θ ₁ > {arcsin (1 / n)} / 2
The surface emitting device according to claim 1, wherein the relationship is satisfied. When the inclination angle of the second reflecting surface of the second reflecting member with respect to the surface substantially orthogonal to the first direction is θ ₂ and the refractive index of the light guide plate is n,
{180-arcsin (1 / n)} / 2> θ ₂ > {arcsin (1 / n)} / 2
The surface emitting device according to claim 1, wherein the surface light emitting device satisfies the following relationship.   The first reflection surface of the first reflection member includes a pair of reflection surfaces that respectively reflect light from the light source to one side and the other side in the first direction. The surface light-emitting device of any one.   The said 1st reflection member is arrange | positioned so that the intersection line of a pair of said reflective surface may oppose the center of the said 1st direction of the main light emission surface of the said light source. Surface emitting device. The light guide plate has a back surface disposed opposite to the light emitting surface,
The at least part of the first reflecting member and the at least part of the second reflecting member are arranged between the light emitting surface and the back surface of the light guide plate. The surface light-emitting device of any one of -5.   The said light source, the said 1st reflection member, and the said 2nd reflection member are integrally provided in the said light-guide plate by heat sealing | fusion, The any one of Claims 1-6 characterized by the above-mentioned. Surface emitting device. The light guide plate has a back surface disposed opposite to the light emitting surface,
The back surface of the light guide plate is formed with a convex portion or a concave portion that guides the light reflected by the second reflecting member to the light emitting surface side and emits the light outward from the light emitting surface. The surface light-emitting device of any one of Claims 1-7.   The surface light-emitting device according to claim 1, wherein the light guide plate is made of a transparent or translucent resin. A surface light-emitting device according to any one of claims 1 to 9,
A display device comprising a display panel illuminated by the surface light emitting device.   An electronic apparatus comprising the display device according to claim 10.

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