Backlight device and liquid crystal display device

Abstract

To provide a backlight device which can maximally suppress a luminance variation which is generated due to a float of a reflection sheet caused by a thickness or the like of a light source baseboard, in a liquid crystal display device in which a direct-type backlight is employed, and the liquid crystal display device.SOLUTION: A backlight device 12 comprises: a backlight chassis 22; a light source baseboard 25 in which a plurality of light sources 24 which are arranged on the backlight chassis 22 are arranged; and a reflection sheet 30 which are arranged on the light source baseboard 25 and the backlight chassis 22 so as to cover the light source baseboard 25 and the backlight chassis 22, and reflecting light. The reflection sheet 30 has a protrusive piece 30e which is formed of a cut line 30d, and in a state that the reflection sheet 30 is arranged, at least a tip part 30e2 of the protrusive piece 30e is inserted between the light source baseboard 25 and the backlight chassis 22.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to a backlight device and a liquid crystal display device. [Background technology]

[0002] Patent Document 1 discloses that in a backlight device in which multiple light source boards are connected via connecting members, the connecting members have to be placed by drilling holes in the reflective sheet due to their thickness, and in order to prevent brightness unevenness caused by the connecting members having a reflectance different from that of the reflective sheet, the connecting members are covered with a covering sheet having a reflectance equal to that of the reflective sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-28043 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, adhesive (bond) fixing methods have become more common for fixing the light source board of a direct-type backlight to the backlight chassis due to the trend to reduce the number of parts. Also, the reflective sheet is fixed by sticking it onto the light source board with double-sided tape, but it may become loose from the light source board and backlight chassis due to deterioration of adhesive performance over long-term use or assembly errors, and there is a concern that it may block the light from the LED (Light-emitting Diode), which is the light source, and cause uneven brightness on the display screen.

[0005] The present disclosure aims to provide a backlight device and a liquid crystal display device that can minimize brightness unevenness caused by the floating of a reflective sheet due to the thickness of a light source substrate, etc., in a liquid crystal display device that employs a direct-type backlight, using a simple configuration. [Means for solving the problem]

[0006] The backlight device of the present disclosure comprises a backlight chassis, a light source board on which a plurality of light sources are arranged and disposed on the backlight chassis, and a reflective sheet that reflects light and is disposed on the light source board and the backlight chassis so as to cover the light source board and the backlight chassis, the reflective sheet having a protrusion formed by a cutting line, and when the reflective sheet is disposed, at least a tip of the protrusion is inserted between the light source board and the backlight chassis.

[0007] The liquid crystal display device of the present disclosure is a liquid crystal display device including the above-mentioned backlight device. Effect of the Invention

[0008] According to the present disclosure, in a liquid crystal display device employing a direct type backlight, it is possible to minimize luminance unevenness caused by the reflection sheet floating due to the thickness of the light source substrate, etc. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing a liquid crystal display device 10 equipped with a backlight device 12 according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is an exploded perspective view of a liquid crystal display device 10. [Diagram 3] FIG. 2 is a plan view of the backlight device 12. [Figure 4] 4 is a cross-sectional view of the backlight device 12 shown in FIG. 3 taken along line IV-IV. [Diagram 5] FIG. 2 is a plan view of a light source substrate 25. [Figure 6] 6 is a cross-sectional view taken along the line VI-VI when the light source board 25 shown in FIG. 5 is disposed on the backlight chassis 22. FIG. [Figure 7] FIG. 2 is a plan view showing a portion of the reflective sheet 30. [Figure 8]10 is a plan view showing a part of the reflective sheet 30 in a state in which the reflective sheet 30 is arranged so as to cover the light source board 25 and the backlight chassis 22. FIG. [Figure 9] 9 is a cross-sectional view taken along line IX-IX of a part of the backlight device 12 shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure will now be described with reference to the accompanying drawings, in which the same or corresponding parts are designated by the same reference characters and will not be described repeatedly.

[0011] (1) Basic Configuration of Backlight Device 12 and Liquid Crystal Display Device 10 A liquid crystal display device 10 including a backlight device 12 according to an embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a perspective view showing the liquid crystal display device 10.

[0012] As shown in FIG. 1, the liquid crystal display device 10 displays an image. The type of image displayed by the liquid crystal display device 10 is not particularly limited. For example, the liquid crystal display device 10 may communicate with a server and display an image represented by image data received from the server. The liquid crystal display device 10 may be connected to an external storage device such as a USB memory and display an image represented by image data acquired from the external storage device. For example, the liquid crystal display device 10 may include a tuner capable of receiving a television image signal and display an image represented by a television image signal received from the tuner.

[0013] The liquid crystal display device 10 will be further described with reference to Fig. 2. Fig. 2 is an exploded view of the liquid crystal display device 10.

[0014] 2 shows an X-axis, a Y-axis, and a Z-axis. The X-axis, the Y-axis, and the Z-axis are perpendicular to each other. In FIG. 2, the upper side of the paper is the front side, and the lower side of the paper is the back side.

[0015] 2, the liquid crystal display device 10 includes a liquid crystal panel 11, a backlight device 12, and a bezel 13. Although not shown, the liquid crystal display device 10 may include a touch panel disposed on the entire surface of the liquid crystal panel 11.

[0016] The liquid crystal panel 11 displays an image. The liquid crystal panel 11 may be any member that displays an image by utilizing light from the backlight device 12.

[0017] The liquid crystal panel 11 has a pair of glass substrates. A liquid crystal layer (not shown) is sealed between the pair of glass substrates. The pair of glass substrates are attached to each other with a predetermined gap therebetween.

[0018] One of the pair of glass substrates is provided with a switching element (e.g., TFT), a pixel electrode, and an alignment film. The switching element is connected to a source wiring and a gate wiring. The pixel electrode is connected to the switching element. The other of the pair of glass substrates is provided with a color filter, a counter electrode, and an alignment film. The color filter has a plurality of colored parts such as R (red), G (green), and B (blue) arranged in a predetermined arrangement. Image data required for displaying an image and various control signals are supplied to the source wiring, gate wiring, and counter electrode from a drive circuit board (not shown). A polarizing plate (not shown) is arranged on the outer side of the pair of glass substrates.

[0019] The backlight device 12 is a direct type backlight device in which LEDs are arranged on the back side of the liquid crystal panel 11. The backlight device 12 irradiates light onto the liquid crystal panel 11. In detail, the backlight device 12 irradiates light onto the liquid crystal arranged in the liquid crystal panel 11.

[0020] The bezel 13 holds the liquid crystal panel 11 and the backlight device 12 together. The bezel 13 is attached to the liquid crystal panel 11 and the backlight device 12 so as to surround the edge of the liquid crystal panel 11.

[0021] The backlight device 12 will be described with reference to Fig. 2 to Fig. 4. Fig. 3 is a plan view of the backlight device 12. Fig. 4 is a cross-sectional view taken along line IV-IV of the backlight device 12 shown in Fig. 3. Note that configurations characteristic of the present disclosure are omitted in Figs. 2 to 4 for the sake of simplicity, and will be described later with reference to Fig. 5 onwards.

[0022] As shown in FIGS. 2 to 4, the backlight device 12 includes a backlight chassis 22, an optical member 23, a light source 24, a light source substrate 25, a frame 26, a lens 27, and a reflective sheet 30. The backlight device 12 includes a backlight chassis 22, an optical member 23, a light source 24, a light source substrate 25, a frame 26, a lens 27, and a reflective sheet 30.

[0023] The backlight chassis 22 is, for example, a resin member. More specifically, the backlight chassis 22 is, for example, a plastic member. The backlight chassis 22 may be made of metal. The backlight chassis 22 houses the reflective sheet 30. The backlight chassis 22 includes a bottom plate 22a, a side plate 22b, and a receiving plate 22c. The bottom plate 22a has a shape corresponding to the liquid crystal panel 11. In the backlight device 12, the bottom plate 22a is formed in a substantially rectangular shape similar to the liquid crystal panel 11. The side plate 22b rises from the edge of the bottom plate 22a toward the liquid crystal panel 11. The receiving plate 22c is continuous with the side plate 22b. The frame 26 and the optical member 23 are installed on the receiving plate 22c. The backlight device 12 may further include a back cover. The back cover covers the back surface of the backlight chassis 22. The backlight chassis 22 and the back cover may be made of different materials. For example, the backlight chassis 22 may be made of resin and the back cover may be made of metal.

[0024] The optical member 23 is formed in a substantially rectangular shape. The optical member 23 is disposed between the liquid crystal panel 11 and the lens 27. The optical member 23 includes a light diffusion plate 23a and an optical sheet 23b.

[0025] Of the light diffusion plate 23a and the optical sheet 23b, the light diffusion plate 23a is disposed on the lens 27 side, and the optical sheet 23b is disposed on the liquid crystal panel 11 side. The light diffusion plate 23a is a substantially plate-shaped member having a predetermined thickness. The light diffusion plate 23a has a structure in which diffusion particles are dispersed within a base material formed from a resin. The light diffusion plate 23a has a function of diffusing light passing through the light diffusion plate 23a.

[0026] The optical sheet 23b is a substantially sheet-like member having a structure in which two sheets are laminated together, and includes at least one of a diffusion sheet, a lens sheet, and a reflective polarizing sheet, for example.

[0027] The frame 26 has a shape that fits the edges of the liquid crystal panel 11 and the optical member 23. The frame 26 and the backing plate 22c sandwich the edges of the optical member 23. The frame 26 also sandwiches the edges of the liquid crystal panel 11 between the frame 26 and the bezel 13.

[0028] The light source 24 is mounted on a light source substrate 25. The light source 24 emits light. The light source 24 includes, for example, an LED (Light Emitting Diode) chip as a light source.

[0029] The light source board 25 extends along the bottom plate 22a inside the backlight chassis 22 and is housed in the backlight chassis 22. A light source 24 is mounted on a surface of the light source board 25 facing the liquid crystal panel 11. A plurality of light sources 24 are provided. The plurality of light sources 24 are arranged, for example, in a matrix so as to form a row and column.

[0030] The base material of the light source substrate 25 is formed of, for example, a metal including an aluminum-based material. A wiring pattern is formed on the surface of the light source substrate 25 via an insulating layer. The wiring pattern is formed of a metal film such as copper foil. A white reflective layer is formed on the surface of the light source substrate 25. The reflective layer of the light source substrate 25 effectively reflects the light emitted from the light source 24 toward the liquid crystal panel 11. Note that an insulating material such as ceramic can also be used as the material for the base material of the light source substrate 25.

[0031] The lens 27 contains, for example, a synthetic resin material (such as polycarbonate or acrylic) that is translucent and has a refractive index higher than that of air. The lens 27 has a predetermined thickness and is formed in a substantially circular shape. A plurality of lenses 27 are provided. The plurality of lenses 27 each cover the plurality of light sources 24 from the liquid crystal panel 11 side. The lens 27 diffuses the light emitted from the light source 24. The directionality of the light emitted from the light source 24 is alleviated by passing through the lens 27. As a result, even if there is a gap between the adjacent light sources 24, it is possible to supply light to the area between the adjacent light sources 24.

[0032] The reflective sheet 30 reflects the light emitted from the light source 24 to the liquid crystal panel 11. The reflective sheet 30 is formed of, for example, a synthetic resin. The reflective sheet 30 is laid over almost the entire inner surface of the backlight chassis 22. The reflective sheet 30 allows the light emitted from the light source 24 to be effectively supplied to the liquid crystal panel 11.

[0033] The reflective sheet 30 includes a bottom portion 30a and rising portions 30b. The bottom portion 30a extends along the bottom plate 22a of the backlight chassis 22. The bottom portion 30a covers the bottom plate 22a. The rising portions 30b rise from the edge of the bottom portion 30a toward the liquid crystal panel 11. The rising portions 30b are inclined with respect to the bottom portion 30a.

[0034] (2) Characteristic configuration of the backlight device 12 Next, a characteristic configuration of the backlight device 12 will be described with reference to Figs. 5 to 9. Fig. 5 is a plan view of the light source board 25. Fig. 6 is a VI-VI cross-sectional view of the light source board 25 shown in Fig. 5 arranged on the backlight chassis 22. Fig. 7 is a plan view showing a part of the reflective sheet 30. Fig. 8 is a plan view showing a part of the reflective sheet 30 arranged so as to cover the light source board 25 and the backlight chassis 22. Fig. 9 is a IX-IX cross-sectional view of a part of the backlight device 12 shown in Fig. 8.

[0035] As shown in Fig. 5, a plurality of light sources 24 are arranged on a light source substrate 25. Here, six light sources 24 are arranged, but the number of light sources 24 is not limited to six. As shown in Fig. 6, the light source substrate 25 is arranged on a backlight chassis.

[0036] 8 and 9, the reflective sheet 30 is disposed on the light source substrate 25 and the backlight chassis 22 so as to cover the light source substrate 25 and the backlight chassis 22, and reflects light. As shown in Figs. 7 and 8, the reflective sheet 30 has protrusions 30e formed by cutting lines 30d.

[0037] Furthermore, as shown in FIGS. 8 and 9, at least the tip 30e2 of the protruding piece 30e is inserted between the light source board 25 and the backlight chassis 22 in a state in which the reflective sheet 30 is arranged.

[0038] Therefore, the protruding pieces 30e prevent the reflection sheet 30 from floating up. As a result, the brightness unevenness caused by the reflection sheet 30 floating up is suppressed.

[0039] The reflective sheet 30 is further provided with openings 30c into which the light sources 24 (the lenses 27 covering the light sources 24) arranged on the light source board 25 are inserted.

[0040] 5, the light source substrate 25 is rectangular, and the multiple light sources 24 are arranged in a row at equal intervals along the longitudinal direction of the light source substrate 25. Therefore, if a single size of light source substrate 25 is prepared, a roughly uniform surface light source can be realized by combining the required number of substrates according to the vertical and horizontal sizes of the backlight device 12. As a result, backlight devices 12 of various sizes can be manufactured without increasing costs. However, the light source substrate 25 is not limited to a rectangular shape. The arrangement of the multiple light sources 24 is also not limited to that shown in FIG. 5.

[0041] 8, in a state where the reflective sheet 30 is arranged, the base 30e1 of the protrusion 30e is disposed outside the end 25a of the light source substrate 25, and the tip 30e2 of the protrusion 30e is disposed inside the end 25a of the light source substrate 25. Therefore, the tip 30e2 of the protrusion 30e can be easily inserted between the light source substrate 25 and the backlight chassis 22, and the reflective sheet 30 is prevented from floating up. As a result, the brightness unevenness caused by the reflective sheet 30 floating up is better suppressed.

[0042] 8 and 9, at least the tip 30e2 of the protrusion 30e is inserted between the light source substrate 25 and the backlight chassis 22 at a position between two adjacent light sources 24 (located under the lens 27). This allows the reflective sheet 30 between the two adjacent light sources 24 to be effectively utilized, and prevents the reflective sheet 30 from lifting up. As a result, brightness unevenness caused by the reflective sheet 30 lifting up is effectively suppressed.

[0043] 7 and 8, the cutting line 30d of the reflection sheet 30 may be crescent-shaped so as to be convex toward the center of the light source substrate 25. The protrusion 30e formed by such a cutting line 30d is semi-elliptical so as to be convex toward the center of the light source substrate 25. Since the reflection sheet 30 has a certain degree of rigidity, the protrusion 30e having such a shape can have its tip 30e2 slip under the light source substrate 25 by lightly pressing down on the upper part of the reflection sheet 30. However, the cutting line 30d and the protrusion 30e are not limited to such shapes.

[0044] 8 and 9, at least the tip 30e2 of the protruding piece 30e is inserted between the light source substrate 25 and the backlight chassis 22 at an intermediate position that is equidistant from two adjacent light sources 24 (located under the lens 27). This effectively prevents the reflective sheet 30 from lifting up between the two adjacent light sources 24. As a result, the luminance unevenness caused by the reflective sheet 30 lifting up is more effectively suppressed.

[0045] As shown in Fig. 6, the light source substrate 25 and the backlight chassis 22 are fixed to each other by partially providing a coating region R1 where an adhesive is applied and a non-coating region R2 where no adhesive is applied between the light source substrate 25 and the backlight chassis 22. Also, as shown in Fig. 8, at least the tip 30e2 of the protruding piece 30e is inserted between the light source substrate 25 and the backlight chassis 22 in the non-coating region R2. Therefore, there is no need to take the trouble of providing a gap between the light source substrate 25 and the backlight chassis 22 for inserting at least the tip 30e2 of the protruding piece 30e. As a result, the backlight device 12 can be manufactured easily.

[0046] In the non-coating region R2, a gap is formed between the light source substrate 25 and the backlight chassis 22, but it is preferable to adjust the amount of adhesive applied in the coating region R1 so that this gap is slightly larger than the thickness of the reflective sheet 30. This is because it is easy to insert the tip 30e2 of the protruding piece 30e between the light source substrate 25 and the backlight chassis 22, and the protruding piece 30e, once inserted, is unlikely to come off.

[0047] The liquid crystal display device 10 is also equipped with a backlight device 12. Therefore, the protruding pieces 30e prevent the reflective sheet 30 from floating up. As a result, it is possible to realize a liquid crystal display device 10 in which brightness unevenness caused by the reflective sheet 30 floating up is suppressed.

[0048] The present invention can be implemented in various other forms without departing from its spirit or main features. Therefore, the above-described embodiments are merely illustrative in all respects and should not be interpreted as being limiting. The scope of the present invention is defined by the claims and is not limited to the text of the specification. Furthermore, all modifications and changes within the equivalent scope of the claims are within the scope of the present invention. [Industrial Applicability]

[0049] The present disclosure can be used in liquid crystal display devices and the like. [Explanation of symbols]

[0050] 10 LCD display device 11 Liquid crystal panel 12 Backlight device 13 Bezel 22 Backlight chassis 23 Optical Components 24 Light source 25 Light source board 26 Frames 27 Lens 30 Reflective Sheet

Claims

1. A backlight chassis; a light source board on which a plurality of light sources are arranged, the light source board being disposed on the backlight chassis; a reflective sheet that reflects light and is disposed on the light source substrate and the backlight chassis so as to cover the light source substrate and the backlight chassis; Equipped with The reflective sheet has a protrusion formed by a cutting line, In a state in which the reflective sheet is disposed, at least a tip portion of the protrusion is inserted between the light source board and the backlight chassis.

2. The backlight device according to claim 1 , wherein when the reflective sheet is disposed, a base of the protrusion is positioned outside an end of the light source substrate, and a tip of the protrusion is positioned inside the end of the light source substrate.

3. 3 . The backlight device according to claim 1 , wherein at least a tip of the protruding piece is inserted between the light source board and the backlight chassis at a position between two adjacent ones of the light sources.

4. 3. The backlight device according to claim 1, wherein at least a tip of the protrusion is inserted between the light source substrate and the backlight chassis at an intermediate position that is equidistant from two adjacent light sources.

5. the light source substrate and the backlight chassis are fixed to each other by partially providing a coating region where an adhesive is applied and a non-coating region where the adhesive is not applied between the light source substrate and the backlight chassis, respectively; 3 . The backlight device according to claim 1 , wherein at least a tip of the protruding piece is inserted between the light source board and the backlight chassis in the non-coated region. 4 .

6. 3. The backlight device according to claim 1, wherein the light source substrate is rectangular, and the plurality of light sources are arranged in a row at equal intervals along a longitudinal direction of the light source substrate.

7. A liquid crystal display device comprising the backlight device according to claim 1 or 2.

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