JP2016213137A - Backlight unit and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backlight unit and a display device capable of improving light guide efficiency and providing an air layer which can prevent swelling, and also preventing luminance distribution of emission light from becoming uneven.SOLUTION: A backlight unit has a laminate structure in which a reflection sheet which reflects incident light and a light guide material which has light transmissivity are laminated in this order, and in which emission light from a light source is imparted to a predetermined incident region out of side surfaces of the laminate. The light guide material is fixed to the reflection sheet by a first fixing layer arranged on a top surface of the reflection sheet, and between the reflection sheet and the light guide material, a first space is formed surrounded by these and the first fixing layer, and at the first fixing layer, a bottomed groove shape first air-vent part is formed which reaches the first space from the incident region. At least one part of the first air-vent part extends in the direction which is not parallel with an optical axis of the light source.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a backlight unit used in a liquid crystal display and other display devices, and a display device including the backlight unit.

  As a backlight unit used in a liquid crystal display or other display device, a unit having a configuration in which a light guide is disposed on a reflection sheet via a first space and an emission sheet is disposed on the light guide via a second space. There is. In this backlight unit, the light emitted from the light source is incident from the side of the light guide, and the light guided by the ride guide is emitted from the output sheet. As the air layer, the first and second spaces are formed. By providing, a backlight unit with improved light guide efficiency can be realized.

  In the above-described backlight unit, there is a problem that air is accumulated in the first and second spaces when the reflection sheet, the light guide, and the emission sheet are bonded together. On the other hand, the structure which prevents a swelling by providing the groove part for releasing the air in 1st and 2nd space is proposed (for example, patent document 1).

JP 2013-49818 A

  However, in the conventional backlight unit, light is easily reflected and scattered light is generated at the interface between the groove and the light guide due to the difference in refractive index between air and the resin constituting the light guide. This phenomenon appears remarkably when the groove is formed along the optical axis direction of the light source. This is because the light intensity of the direct light emitted from the light source and traveling along the optical axis is strong. When such a scattering phenomenon appears, scattered light with high intensity tends to gather in the region near the entrance that enters the first and second spaces from the groove. For this reason, there has been a problem that the in-plane distribution of the luminance of the light emitted from the backlight unit becomes non-uniform.

  Therefore, the present invention can provide an air layer that can increase the light guide efficiency and prevent swelling, and can further prevent the luminance distribution of emitted light from becoming uneven. An object is to provide a light unit and a display device.

  In order to solve the above problems, the backlight unit of the present invention has a laminate structure in which a reflective sheet for reflecting incident light and a light-transmitting light guide material are sequentially laminated. A backlight unit in which light emitted from a light source is given to a predetermined incident area of the side surface, and the light guide material is fixed to the reflective sheet by a first fixing layer disposed on the upper surface of the reflective sheet, A first space surrounded by these and the first fixed layer is formed between the reflection sheet and the light guide material, and the first fixed layer has a bottomed groove shape extending from the incident region to the first space. The first air vent is formed, and at least a part of the first air vent extends in a direction not parallel to the optical axis of the light source.

  According to this configuration, since the first space is provided, high light guide efficiency can be realized, and by providing the first air vent part, air inside the first space is released to the outside. Therefore, swelling can be prevented. Further, since the first air vent extends in a direction not parallel to the optical axis of the light source, the light emitted from the light source and traveling along the optical axis AX is difficult to directly enter the first space. Even if light is reflected / scattered between the first air vent and the light guide material, the scattered light is difficult to travel to the first space with the same intensity. It is possible to suppress strong scattered light from appearing around the entrance to the first space.

The backlight unit of the present invention has an output sheet fixed to the light guide material by a second fixing layer disposed on the upper surface of the light guide material, and between the light guide material and the output sheet, A second space surrounded by two fixed layers is formed, and a second air vent portion having a bottomed groove extending from the incident region to the second space is formed in the second fixed layer, and the second air vent is formed. It is preferable that at least a part of the part extends in a direction not parallel to the optical axis of the light source.
Thereby, the same effect as the 1st space and the 1st air vent part can be acquired.

  In the backlight unit of the present invention, the first air vent has a first slit unit composed of two slits that are symmetrical with respect to the optical axis of the light source, and the second air vent is symmetrical with respect to the optical axis of the light source. It is preferable to have the 2nd slit unit which consists of two slits.

  Thereby, in each of 1st space and 2nd space, since the incident position from two slits used as a pair is lost, the backlight unit which has a well-balanced luminance distribution can be provided.

  In the first aspect of the backlight unit of the present invention, the two slits of the first slit unit are formed so as to approach each other from the incident area toward the first space, and the two slits of the second slit unit. Are preferably formed so as to approach each other from the incident region toward the second space.

  As a result, it is possible to suppress the appearance of strong scattered light from the slits around the entrance to the first space and the second space, thereby making the luminance distribution of the light emitted from the backlight unit non-uniform. Can be prevented.

  In the second aspect of the backlight unit of the present invention, the two slits of the first slit unit are formed so as to be separated from each other toward the first space from the incident region, and the two slits of the second slit unit Are preferably formed so as to be separated from each other toward the second space from the incident region.

  Thereby, since light enters the first space or the second space at a plurality of positions away from the optical axis of the light source, variation in the intensity of incident light in the first space and the second space is reduced. Thus, the luminance distribution as the backlight unit can be made more uniform.

  In the backlight unit of the present invention, it is preferable that a plurality of first slit units and a plurality of second slit units are provided.

  Thereby, the intensity dispersion | variation in the incident light to 1st space and 2nd space can be reduced.

  In the backlight unit of the present invention, it is preferable that the first air vent and the second air vent have the same shape.

  Thereby, since the slit of a 1st air vent part and a 2nd air vent part can be formed in the same procedure, a manufacturing process can be simplified.

  In the backlight unit of the present invention, it is preferable that the first air vent and the second air vent have a linearly extending portion.

  Thereby, the process and dimension management of a slit become easy, and formation of a slit can be performed simply.

  In the backlight unit of the present invention, it is preferable that the first air vent and the second air vent have a portion extending in a curved shape.

  As a result, the crossing angle between the slit and the straight line parallel to the optical axis of the light source can be made close to a right angle, so that light traveling along the optical axis is directly incident on the first space and the second space. It becomes difficult. Further, even if light is reflected / scattered between the slit and the light guide material, the scattered light hardly travels to the first space and the second space with the same intensity.

  In the backlight unit of the present invention, the first fixed layer and the second fixed layer are preferably double-sided tape.

  Thus, the liquid does not enter the first space and the second space as in the case of using the liquid adhesive, and the first space and the second space can be formed in a certain shape. Therefore, the optical characteristics of the backlight unit can be kept constant.

  In the backlight unit of the present invention, the first air vent and the second air vent are preferably formed in a bottomed groove shape by irradiating the double-sided tape with laser light.

  Since the air vent is formed using laser light, it is possible to precisely design and manufacture the shape of the slit. This makes it difficult for dust and the like to enter the first and second air vents and the first and second spaces. Furthermore, since there is no possibility that the first and second fixing layers are separated at the time of manufacturing, the double-sided tape can be easily peeled off, and the workability (assembleability) is improved.

  A display device according to the present invention includes any one of the backlight units described above, a light source that provides outgoing light to an incident region, and a panel that is disposed on the outgoing sheet.

  Thereby, the display apparatus which can acquire the effect which the above-mentioned backlight unit has can be realized.

  In another aspect, a display device according to the present invention includes any one of the above-described backlight units and a light source that provides outgoing light to an incident region, and a panel is disposed as an outgoing sheet.

  Accordingly, it is possible to realize a display device that can obtain the effect of the above-described backlight unit, and to reduce the size of the device.

  According to the present invention, it is possible to increase the light guide efficiency and to provide an air layer that can prevent swelling, and it is possible to prevent the luminance distribution of emitted light from becoming uneven.

(A) is a top view which shows the structure of the backlight unit which concerns on 1st Embodiment, and a light source, (B) is a top view which shows the structure of the backlight unit of FIG. 1 (A). It is sectional drawing in the II-II 'line | wire of FIG. (A), (B), (C), (D), (E) is a figure which shows the structural example of the air vent part on the double-sided tape as a 1st fixed layer, Comprising: The incident area of a backlight unit It is a top view which expands and shows the vicinity. (A), (B), (C), (D), and (E) are provided with slits having patterns shown in FIGS. 3 (A), (B), (C), (D), and (E). It is a figure which shows the measurement result of the luminance distribution at the time of each illuminating with respect to a backlight unit. (A), (B), (C), (D) is a top view which shows the structural example of the air vent part on the double-sided tape as a 1st fixed layer, Comprising: The backlight unit which concerns on 2nd Embodiment It is a top view which expands and shows the vicinity of the incident area | region. (A), (B), (C), (D) respectively illuminate the backlight unit provided with slits having the patterns shown in FIGS. 5 (A), (B), (C), (D). It is a figure which shows the measurement result of the luminance distribution at the time of doing.

  Hereinafter, a backlight unit and a display device according to an embodiment of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
FIG. 1A is a plan view showing the configuration of the backlight unit 10 and the light source 60 according to the first embodiment, and FIG. 1B is a plan view showing the configuration of the backlight unit 10. 2 is a cross-sectional view taken along the line II-II ′ of FIG. 3 (A), (B), (C), (D), and (E) are diagrams showing a configuration example of an air vent on the double-sided tape 30 as the first fixed layer, and a backlight unit It is a top view which expands and shows the vicinity of 10 incident area | regions 12. FIG. 3A shows an example in which no air vent is provided, FIG. 3B shows a pattern of slits 31a and 31b in the first embodiment, and FIG. 3C shows slits 32a, 32b, 33a in the first modification. (B) shows the pattern of slits 35a, 35b, 35c, 36a, 36b, 37a, 37b in the second modification, and (E) shows the slit 38a in the third modification. The patterns 38b, 39a, 39b are shown. The line III-III ′ in FIG. 3B corresponds to the line II-II ′ in FIG. In each figure, XYZ coordinates are shown as reference coordinates. The Z direction is the height direction of the backlight unit, and is along the stacking direction of the reflection sheet 21, the light guide material 22, and the diffusion sheet 23. The XY plane is a plane orthogonal to the Z direction. In the following description, the state viewed from the Z direction may be referred to as a plan view.

  As shown in FIG. 1 or 2, the backlight unit 10 according to the first embodiment includes a reflective sheet 21, a light guide material (light guide) 22, and a diffusion sheet 23 as an output sheet, which are sequentially stacked. A laminate structure is provided. The display device 100 according to the first embodiment includes a backlight unit 10, a light source 60, and a panel 70 as shown in FIG. The light source 60 is a light emitting diode (LED), for example, and has an optical axis AX. The panel 70 is a liquid crystal panel used for, for example, a watch, a portable information terminal, a liquid crystal display, a liquid crystal television, and the like.

  As shown in FIGS. 1A and 1B, the backlight unit 10 has a substantially rectangular shape in plan view. On the side surface on the right side in the X direction of the side surface 11 of the backlight unit 10, a concave portion recessed inward is formed so as to accommodate the emission portion 61 of the light source 60. The concave portion serves as an incident region 12 (FIG. 1B) where light emitted from the light emitting portion 61 of the light source 60 enters, and the light emitting portion 61 is disposed so as to face at least the light guide material 22. The side surface 11 of the backlight unit 10 is configured such that outside light is not incident by a light-shielding coating, a light-shielding tape, or the like except for the incident region 12.

  The reflection sheet 21 is a rectangular sheet material that reflects light incident from above on the upper surface 21a. For example, the reflection sheet 21 has a metal reflection layer formed on the surface of a resin material by coating, vapor deposition, sputtering, or the like. It is. The light scattered by the light guide material 22 enters the reflection sheet 21, and the scattered light is reflected by the upper surface 21 a of the reflection sheet 21 and travels again toward the lower surface 22 b of the light guide material 22.

  The light guide member 22 is, for example, a diffusing plate, and has translucency, scatters light incident from the side surface 22c, and emits the light from the upper surface 22a and the lower surface 22b to the outside. The light guide member 22 has a rectangular shape that is the same shape as the reflection sheet 21 in plan view, and is provided by a double-sided tape 30 as a first fixed layer disposed along the outer edge portion of the upper surface 21 a of the reflection sheet 21. It is fixed to the reflection sheet 21. Note that an adhesive having low fluidity can also be used as the first fixed layer.

  A first space 30 a surrounded by these and the double-sided tape 30 is formed between the reflection sheet 21 and the light guide material 22. The first space 30a corresponds to the emission region of the backlight unit 10 in plan view.

  As shown in FIG. 3B, the double-sided tape 30 is formed with a first air vent 31 composed of two slits 31a and 31b. The two slits 31a and 31b are formed as a bottomed groove-shaped half cut on the double-sided tape 30 by, for example, irradiating the double-sided tape 30 with laser light from the upper side in the Z direction. The two slits 31 a and 31 b are formed so as to reach the first space 30 a from the incident region 12 on the side surface 11 of the backlight unit 10. With such a configuration, the first space 30a functions as an air layer and is connected to the outside of the backlight unit 10 through the two slits 31a and 31b, so that the internal pressure is maintained at atmospheric pressure. Therefore, it is possible to suppress the occurrence of swelling due to the accumulation of air at the time of assembling the backlight unit 10 or the expansion of the air due to the temperature change during driving.

  As shown in FIG. 3B, the two slits 31 a and 31 b are paired, have a linear pattern shape that is symmetrical with respect to the optical axis AX of the light source 60, and the first space 30 a from the incident region 12. It is formed to approach each other as it goes to. In other words, the two slits 31a and 31b are arranged at an angle that intersects a straight line parallel to the optical axis AX. Here, the two slits constituting the second air vent 41 also have the same pattern shape as the slits 31a and 31b and are paired. The pair of slits 31a and 31b of the first air vent part 31 constitutes a first slit unit, and similarly, the pair of slits of the second air vent part 41 constitutes a second slit unit.

  As shown in FIG. 3C, the first air vent 31 may have a plurality of first slit units. In the first modification shown in FIG. 3C, the innermost two slits 32a and 32b, the outer two slits 33a and 33b, and the outer two slits 34a and 34b form a pair, respectively. A first slit unit is configured. In each of these slit units, the two slits to be paired are in a linear pattern shape symmetrical with respect to the optical axis AX of the light source 60 and incident as in the case of the two slits 31a and 31b shown in FIG. It forms so that it may mutually approach as it goes to the 1st space 30a from the area | region 12. FIG.

  Further, as shown in FIG. 3D, a part along the optical axis AX of the light source 60 may be included in a part of the slit of the first air vent 31. In the second modified example shown in FIG. 3D, as in FIG. 3C, the two innermost slits 35a and 35b, the outer two slits 36a and 36b, and the outer two slits 37a. 37b form a pair, and each constitutes a first slit unit. Further, the innermost two slits 35a and 35b are connected to a slit 35c extending along the optical axis AX at an intersection portion on the first space 30a side.

  Furthermore, as shown in FIG. 3E, a part extending in a curved shape may be included in a part of the slit of the first air vent 31. In the third modification shown in FIG. 3 (E), two slits 38a and 38b formed along a virtual circle 38c and straight lines respectively connected to the tips of these slits on the first space 30a side. A first air vent 31 is formed by the slits 39a and 39b. The continuous slits 38a and 39a and the continuous slits 38b and 39b are paired with each other to form a first slit unit, which is symmetrical with respect to the optical axis AX of the light source 60, and is first from the incident region 12. It is formed so that it may mutually approach as it goes to the space 30a.

  The diffusing sheet 23 is, for example, a diffusing plate, and has translucency, and scatters light incident from the lower surface 23b and emits the light from the upper surface 23a to the outside. The diffusion sheet 23 has a rectangular shape that is the same shape as the light guide material 22 in plan view, and is disposed along the outer edge portion of the upper surface 22a of the light guide material 22 and is a double-sided tape 40 as a second fixed layer. It is fixed to the light guide 22 by. The shape of the double-sided tape 40 is the same as that of the double-sided tape 30, and is disposed along the outer edge portion of the upper surface 22 a of the light guide material 22. An adhesive having low fluidity can also be used as the second fixed layer.

  A second space 40 a surrounded by these and the double-sided tape 40 is formed between the light guide material 22 and the diffusion sheet 23. Further, the double-sided tape 40 is formed with two slits having the same shape as the two slits 31a and 31b formed on the double-sided tape 30 by the same manufacturing method. The air vent part 41 is configured. Similar to the slits 31a and 31b, the two slits constituting the second air vent are formed so as to reach from the incident region 12 to the second space 40a. With such a configuration, the second space 40a functions as an air layer similarly to the first space 30a, and is connected to the outside of the backlight unit 10 through two slits, thereby suppressing the occurrence of swelling.

  On the upper surface 23 a of the diffusion sheet 23, a double-sided tape 50 as a third fixed layer is disposed along the outer edge portion. The shape of the double-sided tape 50 is the same as that of the double-sided tapes 30 and 40, and is disposed along the outer edge portion of the upper surface 23 a of the diffusion sheet 23. As shown in FIG. 2, a translucent panel 70 such as a liquid crystal panel is fixed to the upper part of the backlight unit 10 by the double-sided tape 50.

  Between the double-sided tape 50 and the panel 70, a third space 50a surrounded by these and the double-sided tape 50 is formed. The double-sided tape 50 is preferably provided with two slits having a bottomed groove like the two slits 31 a and 31 b formed on the double-sided tape 30. With such a configuration, the third space 50a also functions as an air layer in the same manner as the first space 30a and the second space 40a, and is connected to the outside of the backlight unit 10 through two slits, thereby generating swelling. Can be suppressed. An adhesive having low fluidity can also be used as the third fixed layer.

  In this way, the display device 100 is configured by disposing the light source 60 so that the emission part 61 faces the incident region 12 of the side surface 11 of the backlight unit 10 to which the panel 70 is fixed.

  4 (A), (B), (C), (D), and (E) are slits having patterns shown in FIGS. 3 (A), (B), (C), (D), and (E). It is a figure which shows the measurement result of the luminance distribution at the time of each illuminating with respect to the provided backlight unit. 4A, 4B, 4C, 4D, and 4E show the luminance distribution in the range of the first space 30a, and the right side of the drawing shows the first air vent 31 and the second air vent. This corresponds to the area where the air vent 41 is provided.

The illumination conditions and measurement conditions for the measurements shown in FIGS. 4 (A) to (E) are as follows.
(1) About light source White LED / NSSW204C (manufactured by Nichia Corporation)
Drive current value 5mA
(2) About each layer The thickness of the reflective sheet 21: 53um
Light guide 22 thickness: 150um
Thickness of diffusion sheet 23: 40um
Planar shapes of the reflection sheet 21, the light guide material 22, and the diffusion sheet 23:
(I) Reflective sheet 21: Sandblasted smooth sheet (II) Light guide 22: Dot concave shape for light extraction on one side (III) Diffusion sheet 23: Smooth sheet (3) Double-sided tape 30 and slit About Shape of double-sided tape 30: width 0.5-1.0mm, thickness 30um (made by Teraoka Seisakusho Co., Ltd.)
Slit depth: 15 ± 3um
Slit width: 0.3 ± 0.1mm
The slit was formed by irradiating the double-sided tape 30 with laser light.
(4) About luminance measurement Measurement environment: dark room Measuring machine: two-dimensional color luminance meter CA-2000 (manufactured by Konica Minolta)
Illumination pattern:
On the upper surface 22a side of the light guide member 22, a dot-like concave shape regularly arranged was formed by irradiating with laser light. The depth and diameter of the concave shape are optimized depending on the processing location.

  As shown in FIG. 4A, in the configuration in which no air vent is provided, there is no air layer between the light guide 22 and the double-sided tape 30 and between the double-sided tape 40 and the diffusion sheet 23. The diffusion of light in the portions of the double-sided tapes 30 and 40 is reduced. On the other hand, according to the measurement results shown in FIGS. 4B, 4 </ b> C, 4 </ b> D, and 4 </ b> E, in the double-sided tapes 30 and 40, each other from the incident region 12 toward the first space 30 a. Since the pattern-shaped slits are formed so as to approach each other, diffusion of light generated in the slits is difficult to spread to the first space 30a and the second space 40a. ).

With the configuration as described above, the following effects are achieved according to the first embodiment.
(1) Since the first space 30a and the second space 40a are provided, high light guide efficiency can be obtained, and slits as the first air vent 31 and the second air vent 41 are provided. Thus, since the air inside the first space 30a and the second space 40a can be released to the outside, the swelling can be prevented.

(2) In the first air vent 31 and the second air vent 41, the slit is provided so as to extend in a direction not parallel to the optical axis AX of the light source 60. For this reason, the light emitted from the light source 60 and traveling along the optical axis AX is difficult to directly enter the first space 30a and the second space 40a. In addition, even if light is reflected / scattered between the slit and the light guide material 22, it is difficult for the scattered light to travel to the first space 30a and the second space 40a with the same intensity. It is possible to suppress the appearance of strong scattered light around the entrance to the first space 30a and the second space 40a, and thereby the luminance distribution of the light emitted from the backlight unit 10 becomes non-uniform. Can be prevented.

(3) Since the paired slits are formed symmetrically with respect to the optical axis AX of the light source 60, there is no bias in the incident position from each slit in each of the first space 30a and the second space 40a. Therefore, it is possible to provide a backlight unit having a well-balanced luminance distribution.

(4) Since the slits to be paired are formed so as to approach each other from the incident region 12 toward the first space 30a and the second space 40a, the first space 30a and the second space are formed from each slit. It is possible to suppress the appearance of strong scattered light around the entrance to the space 40a, and thus it is possible to prevent the luminance distribution of the light emitted from the backlight unit 10 from becoming uneven.

(5) When a plurality of slit units are provided, the incident positions on the first space 30a and the second space 40a can be dispersed, so that the luminance distribution of the light emitted from the backlight unit 10 is made more uniform. Can do.

(6) The first air vent 31 and the second air vent 41 have the same shape. Thereby, since the slit of the 1st air vent part 31 and the 2nd air vent part 41 can be formed in the same procedure, it can contribute to simplification of a manufacturing process.

(7) Since the slits of the first air vent 31 and the second air vent 41 have a linearly extending portion, it is easy to process and manage the dimensions of this portion, and the slit can be easily formed. it can.

(8) Since the slits of the first air vent 31 and the second air vent 41 have a portion extending in a curved line, the crossing angle with the straight line parallel to the optical axis AX of the light source 60 is made close to a right angle in this portion. Therefore, the light emitted from the light source 60 and traveling along the optical axis AX is difficult to directly enter the first space 30a and the second space 40a, and the slit and the light guide material 22 Even if light is reflected / scattered between the first space 30a and the second space 40a, the scattered light hardly travels to the first space 30a and the second space 40a.

(9) By using the double-sided tapes 30 and 40 as the first fixing layer and the second fixing layer, the first fixing layer and the second fixing layer 40 enter the first space 30a and the second space 40a like a liquid adhesive. Since the first space 30a and the second space 40a can be formed in a certain shape, the optical characteristics of the backlight unit 10 can be kept constant.

(10) By making the slit a half-cut with a bottomed groove, it is easy to prevent the entry of dust and dirt from the outside, and the slit is formed compared to a shape that completely penetrates the double-sided tape in the thickness direction. Since there is no possibility that the double-sided tape will be separated later, it becomes easy to peel off the protective tape after the grooves are formed.

A modification will be described below.
Instead of the backlight unit 10 of the first embodiment, the backlight unit may be configured by the reflection sheet 21, the double-sided tape 30, and the light guide material 22 without providing the diffusion sheet 23. In this case, as a display device, a panel is arranged instead of the diffusion sheet 23 of the first embodiment.

  In each of the first air vent part 31 and the second air vent part 41, the pattern shape of the pair of slits is symmetrical with respect to the optical axis AX of the light source 60, and the first space 30a or the second space from the incident region 12 is the same. The pattern shapes other than those shown in FIGS. 3B, 3 </ b> C, 3 </ b> D, and 3 </ b> E may be used as long as they approach each other toward the space 40 a. This pattern shape may include a portion parallel to the optical axis AX and a portion perpendicular to the optical axis AX.

  In each of the first air vent part 31 and the second air vent part 41, the pattern shape of the pair of slits may include an asymmetric part with respect to the optical axis AX of the light source 60, but the first space 30a or the second The position connected to the space 40a is preferably symmetric with respect to the optical axis AX.

  The slit pattern in the first air vent 31 and the slit pattern in the second air vent 41 may not be the same.

Second Embodiment
In 2nd Embodiment, the pattern of the slit of an air vent part differs from 1st Embodiment. Since other configurations are the same as those of the first embodiment, detailed description thereof is omitted.

  FIGS. 5A, 5 </ b> B, 5 </ b> C, and 5 </ b> D are plan views showing a configuration example of an air vent portion on the double-sided tape 130 as the first fixed layer, according to the second embodiment. It is a top view which expands and shows the vicinity of the incident area of a backlight unit. 5A shows an example in which no air vent is provided, FIG. 5B shows a pattern of slits 131a and 131b in the second embodiment, and FIG. 5C shows a pattern of slits 132a and 132b in the first modification. (D) shows the pattern of slits 133a, 133b, 134a, 134b in the second modification.

  Similar to the double-sided tape 30 of the first embodiment, a double-sided tape 130 as a first fixing layer is disposed on the upper surface 21 a of the reflective sheet 21 along the outer edge portion, and is guided by the double-sided tape 130. A material 22 is fixed to the reflection sheet 21. Thereby, the 1st space 130a enclosed by these and the double-sided tape 130 is formed between the reflective sheet 21 and the light guide material 22 similarly to the 1st space 30a of 1st Embodiment.

  As shown in FIG. 5B, the double-sided tape 130 is formed with a first air vent 131 composed of two slits 131a and 131b. The two slits 131a and 131b are formed on the double-sided tape 130 so as to form a bottomed groove-shaped half cut from the incident region 12 to the first space 130a, similarly to the slits 31a and 31b of the first embodiment. Is done. With such a configuration, the first space 130a functions as an air layer and is connected to the outside of the backlight unit 10 through the two slits 131a and 131b, so that the internal pressure is maintained at atmospheric pressure. Therefore, it is possible to suppress the occurrence of swelling due to the accumulation of air during assembly or the expansion of air due to temperature changes during driving.

  Further, as shown in FIG. 5B, the two slits 131a and 131b are paired, have a curved pattern shape symmetrical with respect to the optical axis AX of the light source 60, and have a first shape from the incident region 12. It forms so that it may mutually leave | separate as it goes to the space 130a. In other words, the two slits 131a and 131b are arranged at an angle that intersects a straight line parallel to the optical axis AX. Further, the two slits constituting the second air vent provided at the outer edge portion of the upper surface 22a of the light guide member 22 have the same shape as the slits 131a and 131b and are paired. The pair of slits 131a and 131b of the first air vent part 131 constitutes a first slit unit, and similarly, the pair of slits of the second air vent part constitutes a second slit unit.

  The first air vent 131 may have a curved pattern shape (FIG. 5C) having a shape different from that of the slits 131a and 131b shown in FIG. In the first modification shown in FIG. 5C, the two slits 132a and 132b that form a pair constitute a first slit unit. The two slits 132a and 132b are formed so as to be further away from each other as compared with the slits 131a and 131b shown in FIG.

  Moreover, the 1st air vent part 131 can also have the structure which has two or more 1st slit units, as shown to FIG 5 (D). In the second modification shown in FIG. 5D, the inner two slits 133a and 133b make a pair, and the outer two slits 134a and 134b also make a pair, and each constitutes a first slit unit. doing. In each of these slit units, the two slits that make a pair have a curved pattern shape that is symmetrical with respect to the optical axis AX of the light source 60 and is incident as in the case of the two slits 131a and 131b shown in FIG. It is formed so as to be separated from each other as it goes from the region 12 toward the first space 130a.

  Here, the slits constituting the first air vent 131 and the second air vent are not only the curved pattern shown in FIGS. 5B, 5C, and 5D, but also a linear pattern, a curve and a straight line. The combined pattern shape may be included, and a pattern shape along the optical axis AX or a pattern shape perpendicular to the optical axis AX may be included in part.

  6 (A), (B), (C), and (D) show the backlight unit provided with slits having the patterns shown in FIGS. 5 (A), (B), (C), and (D). It is a figure which shows the measurement result of the luminance distribution at the time of each illuminating. 6 (A), (B), (C), and (D) show the luminance distribution in the range of the first space 130a, as in FIGS. 4 (A) to 4 (E). This corresponds to the region where the first air vent 131 is provided. The illumination conditions and measurement conditions for the measurements shown in FIGS. 6A to 6D are the same as in the first embodiment.

As shown in FIG. 6A, in the configuration in which the air vent is not provided, the diffusion of light in the double-sided tape portion is reduced as in the configuration shown in FIG. On the other hand, according to the measurement results shown in FIGS. 6B, 6 </ b> C, and 6 </ b> D, the paired slits are formed so as to be separated from each other toward the first space 130 a from the incident region 12. Therefore, light enters the first space 130a at a plurality of positions away from the optical axis AX. For this reason, the variation in luminance is further reduced as compared with the configuration shown in FIG. 6A, and the luminance distribution of the entire first space 130a is closer to a uniform one.
Other operations, effects, and modifications are the same as those in the first embodiment.

  Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above embodiment, and can be improved or changed within the scope of the purpose of the improvement or the idea of the present invention.

  As described above, the backlight unit according to the present invention is useful for a display device that is required to have a high light guide efficiency and a uniform luminance distribution.

DESCRIPTION OF SYMBOLS 10 Backlight unit 12 Incident area 21 Reflection sheet 22 Light guide material 23 Diffusion sheet (output sheet)
30 Double-sided tape 30a First space 31 First air vent 31a, 31b Slit 32a, 32b, 33a, 33b, 34a, 34b Slit 35a, 35b, 35c, 36a, 36b, 37a, 37b Slit 38a, 38b, 39a, 39b Slit 40 Double-sided tape 40a 2nd space 41 2nd air vent part 50 Double-sided tape 50a 3rd space 60 Light source 61 Output part 70 Panel 100 Display device 130 Double-sided tape 130a 1st space 131 1st air vent part 131a, 131b Slit 132a, 132b Slit 133a, 133b, 134a, 134b Slit AX Optical axis

Claims (13)

It has a laminated structure in which a reflective sheet for reflecting incident light and a light-transmitting light guide material are laminated in order, and light emitted from the light source is given to a predetermined incident area on the side surface of the laminated body. A backlight unit,
The light guide material is fixed to the reflection sheet by a first fixing layer disposed on the upper surface of the reflection sheet,
Between the reflection sheet and the light guide material, a first space surrounded by these and the first fixed layer is formed,
The first fixed layer is formed with a bottomed groove-shaped first air vent from the incident region to the first space;
The backlight unit according to claim 1, wherein at least a part of the first air vent extends in a direction not parallel to the optical axis of the light source. Having an exit sheet fixed to the light guide by a second fixing layer disposed on the top surface of the light guide;
Between the light guide material and the output sheet, a second space surrounded by these and the second fixed layer is formed,
The second fixed layer is formed with a bottomed groove-shaped second air vent from the incident region to the second space,
2. The backlight unit according to claim 1, wherein at least a part of the second air vent extends in a direction not parallel to the optical axis of the light source. The first air vent has a first slit unit composed of two slits symmetrical about the optical axis of the light source,
The backlight unit according to claim 2, wherein the second air vent includes a second slit unit including two slits symmetrical with respect to the optical axis of the light source. The two slits of the first slit unit are formed so as to approach each other from the incident area toward the first space,
4. The backlight unit according to claim 3, wherein the two slits of the second slit unit are formed so as to approach each other from the incident region toward the second space. 5. The two slits of the first slit unit are formed to be separated from each other toward the first space from the incident region,
4. The backlight unit according to claim 3, wherein the two slits of the second slit unit are formed so as to be separated from each other toward the second space from the incident region. 5.   The backlight unit according to any one of claims 3 to 5, wherein a plurality of the first slit unit and the second slit unit are provided.   The backlight unit according to any one of claims 2 to 6, wherein the first air vent and the second air vent have the same shape.   The backlight unit according to any one of claims 2 to 7, wherein the first air vent and the second air vent have a linearly extending portion.   The backlight unit according to any one of claims 2 to 8, wherein the first air vent and the second air vent have a portion extending in a curved shape.   The backlight unit according to any one of claims 2 to 9, wherein the first fixed layer and the second fixed layer are double-sided tapes.   The backlight unit according to claim 10, wherein the first air vent and the second air vent are formed in a bottomed groove shape by irradiating the double-sided tape with laser light. The backlight unit according to any one of claims 2 to 11,
The light source for providing outgoing light to the incident region;
A display device comprising a panel disposed on the emission sheet. The backlight unit according to any one of claims 2 to 11,
The light source for providing outgoing light to the incident area;
A display device, wherein a panel is disposed as the exit sheet.