Illumination device and display device

Abstract

To provide an illumination device that can suppress an occurrence of a failure in a reflector and reduction in illumination brightness, and to provide a display device including the illumination device.SOLUTION: An illumination device includes a lattice-shaped reflector surrounding each of a plurality of light sources mounted on a circuit board. The reflector includes a plurality of first portions along an X direction and a plurality of second portions along a Y direction. The plurality of second portions include a specific portion 62D divided in the X direction. The specific portion 62D includes a first adjacent portion 8 and a second adjacent portion 9. The first adjacent portion 8 has a first inner side surface 81 and a first upper surface 82. The second adjacent portion 9 has a second inner side surface 91 facing the first inner side surface 81 in the X direction, a second upper surface 92, and a bottom surface 93. The width of the bottom surface 93 in the X direction is equal to or larger than an interval between the first inner side surface 81 and the second inner side surface 91.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present disclosure relates to a lighting device and a display device including the same. [Background technology]

[0002] For example, Patent Document 1 describes a display device that is mounted on a circuit board and capable of controlling the lighting of multiple light sources that illuminate a liquid crystal panel from behind using local dimming. Local dimming is a technology that controls the brightness of the light source that illuminates the liquid crystal panel for each of multiple areas (dimming zones). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-104781 Summary of the Invention [Problem to be solved by the invention]

[0004] In this type of display device, a lattice-shaped reflector is fixed to a circuit board, surrounding each of the light sources (i.e., defining a dimming zone), and an optical sheet such as a diffusion plate is provided between the reflector and the liquid crystal panel.

[0005] Reflectors are generally fixed to the circuit board with double-sided tape, but as display devices become larger, the difference in linear expansion coefficient between the circuit board and the reflector can cause the reflector to warp or the double-sided tape to peel off, potentially resulting in problems with the reflector. One idea to avoid this is to divide the reflector, but simply dividing the reflector can result in light reflected by the optical sheet entering gaps created by the division, potentially reducing the brightness (illumination brightness) when illuminating the liquid crystal panel.

[0006] The present disclosure has been made in consideration of the above-described situation, and aims to provide an illumination device that can prevent malfunctions in reflectors and reductions in illumination brightness, and a display device equipped with the same. [Means for solving the problem]

[0007] In order to achieve the above object, a lighting device according to a first aspect of the present disclosure comprises: a circuit board on which a plurality of light sources are mounted; an optical sheet that is opposed to the circuit board with a gap therebetween and has light-transmitting properties; a lattice-shaped reflector positioned between the circuit board and the optical sheet and surrounding each of the plurality of light sources, wherein the lighting device illuminates an object with the plurality of light sources controllable by local dimming, The reflector is a plurality of first portions arranged along a first direction and spaced apart in a second direction intersecting the first direction; a plurality of second portions arranged along the second direction and spaced apart in the first direction; the plurality of second portions include specific portions divided in the first direction, the specific portion includes a first adjacent portion and a second adjacent portion adjacent to each other with a gap in the first direction, the first adjacent portion has a first inner side surface facing the second adjacent portion and a first upper surface connected to an upper end of the first inner side surface and facing the optical sheet; the second adjacent portion has a second inner side surface facing the first inner side surface in the first direction, a second upper surface connected to an upper end of the second inner side surface and facing the optical sheet, and a bottom surface connected to a lower end of the second inner side surface and facing the optical sheet, The width of the bottom surface in the first direction is equal to or greater than the distance between the first inner side surface and the second inner side surface.

[0008] In order to achieve the above object, a display device according to a second aspect of the present disclosure comprises: The illumination device and a liquid crystal panel as the target are provided. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to prevent defects in the reflector and a decrease in illumination brightness. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram of a display device according to an embodiment of the present disclosure. [Figure 2] FIG. [Figure 3] 2. FIG. 3 is a cross-sectional view of the illumination unit according to the embodiment of the present invention taken along line II in FIG. [Figure 4] FIG. 2 is a front perspective view of the circuit board and the double-sided tape according to the embodiment; [Figure 5] 2. FIG. 3 is a cross-sectional view of the illumination unit according to the embodiment taken along line II-II in FIG. [Figure 6] FIG. 2 is a rear perspective view of the reflector and the light source according to the embodiment; [Figure 7] FIG. 6 is a cross-sectional view corresponding to FIG. 5, showing a reflector according to a comparative example. [Figure 8] 3 is a cross-sectional view of a specific portion of the reflector according to the embodiment taken along line III-III in FIG. 2. [Figure 9] FIG. 10 is a cross-sectional view of a specific portion of a reflector according to a first modified example. [Figure 10] FIG. 10 is a cross-sectional view of a specific portion of a reflector according to a second modification. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present disclosure will be described with reference to the drawings.

[0012] The display device 100 shown in Fig. 1 includes a liquid crystal panel 1, an illumination device A that illuminates the liquid crystal panel 1 from behind, a housing 4 that houses these, and a control unit (not shown). The liquid crystal panel 1 is, for example, a TFT (Thin Film Transistor) type. The housing 4 is made of metal. The display device 100 is, for example, a meter provided on an instrument panel of a vehicle.

[0013] In the following, the components of the display device 100 may be described using the mutually orthogonal X, Y, and Z axes as appropriate. The direction in which the arrows indicating the X, Y, and Z axes point is the + (plus) direction of each axis, and the opposite direction is the - (minus) direction. The +Z direction is the top of the display device 100, and the -Z direction is the bottom of the display device 100. The top surface of a given component of the display device 100 is also referred to as the front surface, and the bottom surface is also referred to as the back surface.

[0014] The lighting device A includes an illumination unit 2 and an optical sheet 3 provided between the liquid crystal panel 1 and the illumination unit 2. The optical sheet 3 has a translucent configuration that homogenizes the light from the illumination unit 2 and delivers it to the liquid crystal panel 1, and is made up of a light diffusion sheet, a prism sheet, a reflective polarizing sheet, or the like. The optical sheet 3 faces a circuit board 5 (described later) with a gap therebetween.

[0015] As shown in appropriate drawings of FIGS. 2 to 6, the lighting unit 2 includes a circuit board 5, a reflector 6, and a double-sided tape .

[0016] The circuit board 5 is a PCB (Printed Circuit Board). For example, the main surface of the circuit board 5 is parallel to the XY plane. A plurality of light sources 5a are mounted on the circuit board 5 and arranged in the X and Y directions. For example, the light sources 5a are LEDs (Light-Emitting Diodes). The back surface of the circuit board 5 includes a portion that is fixed to the metal housing 4 with thermally conductive double-sided tape (not shown) and a portion that contacts the metal housing 4 via thermally conductive grease (not shown). This allows heat generated by the light sources 5a to be transferred to the metal housing 4 and dissipated from the housing 4.

[0017] The multiple light sources 5a can be controlled by a control unit (not shown) using local dimming. That is, the brightness of the light sources 5a is controlled for each dimming zone. In this embodiment, one light source 5a is provided for each dimming zone. The control unit (not shown) is electrically connected to each of the liquid crystal panel 1 and the circuit board 5, and is configured with a microcontroller that controls the operation of the liquid crystal panel 1 and the multiple light sources 5a.

[0018] The reflector 6 is formed in a lattice shape surrounding each of the multiple light sources 5a. The reflector 6 is formed, for example, from a white resin. As shown mainly in FIG. 6 , of the lattice-shaped reflector 6, a portion along the X direction is defined as a first portion 61, and a portion along the Y direction is defined as a second portion 62. In other words, the reflector 6 has the first portion 61 and the second portion 62.

[0019] Specifically, the first portions 61 are arranged along the X direction (an example of a first direction) and at intervals in the Y direction (an example of a second direction), and the second portions 62 are arranged along the Y direction and at intervals in the X direction.

[0020] Here, one light source 5a is surrounded by one surrounding wall 60, which is made up of a pair of adjacent first portions 61 and a pair of adjacent second portions 62 (see the dashed line in FIG. 2). In other words, a dimming zone is defined by the surrounding wall 60. The surrounding wall 60 that defines one dimming zone reflects light emitted by the light source 5a located therein and guides the light to the liquid crystal panel 1. The reflector 6, in which a plurality of such surrounding walls 60 are arranged in a matrix, guides the light from the light source 5a to the liquid crystal panel 1 for each dimming zone.

[0021] The double-sided tape 7 is configured to fix the reflector 6 to the circuit board 5. The double-sided tape 7 is strip-shaped and extends in the X direction as shown in FIG. 4, and is located between the circuit board 5 and the surface of the first portion 61 facing the circuit board 5 as shown in FIG.

[0022] In this embodiment, the double-sided tape 7 is provided on each of the multiple first portions 61 of the reflector 6, but is not provided along the multiple second portions 62. If the double-sided tape 7 were to be applied to both the first portions 61 and the second portions 62, double-sided tape 7 extending in both the X and Y directions would be used, which would make it difficult to fix the reflector 6 to the circuit board 5. On the other hand, in this embodiment, the reflector 6 can be fixed to the circuit board 5 by the multiple double-sided tapes 7 extending in the X direction, and therefore the reflector 6 can be easily fixed to the circuit board 5.

[0023] 5, a recess 62a recessed in a direction away from the circuit board 5 (+Z direction) is formed on the surface of the second portion 62 facing the circuit board 5. The recess 62a is also shown in the rear perspective view of the reflector 6 and the light source 5a shown in FIG.

[0024] FIG. 7 shows a comparative example of a reflector 6r in which the second portion 62r shown in FIG. 5 does not have a recess 62a. When the reflector 6r is fixed to the circuit board 5 using multiple double-sided tapes 7 extending in the X direction, a gap corresponding to the thickness of the double-sided tapes 7 is formed between the circuit board 5 and the second portion 62r located between adjacent light sources 5a in the X direction. As a result, as shown by the dashed arrows in FIG. 7, there is a risk of light leakage from one dimming zone to the other dimming zone of adjacent light sources 5a in the X direction. This light leakage may make it difficult to illuminate the desired dimming zone with the desired brightness.

[0025] 5, in this embodiment as well, a gap corresponding to the thickness of the double-sided tape 7 is formed between the second portion 62 and the circuit board 5, which may cause light leakage from one dimming zone to the other dimming zone of adjacent light sources 5a in the X direction. However, because the recess 62a is provided in the second portion 62, even if light from a certain light source 5a enters between the second portion 62 and the circuit board 5, the light is weakened by repeated reflection between the recess 62a and the circuit board 5. Therefore, even if light leakage from one dimming zone to the other dimming zone of adjacent light sources 5a in the X direction occurs, the amount of light leakage is effectively reduced compared to the comparative example of FIG.

[0026] 5, the recesses 62a do not have to be provided in all of the second portions 62 of the reflector 6, and as shown in Fig. 5, the recesses 62a do not have to be provided in the second portions 62 that form the edges of the reflector 6. As will be described later, the specific portion 62D of the second portions 62 does not have the recesses 62a, but the specific portion 62D may also have the recesses 62a.

[0027] For example, the recess 62a is formed in a V-shape in cross section as shown in Fig. 5, but is not limited to this shape. The recess 62a may have any shape, such as a concave curved surface or a W-shape, as long as it can reduce light leakage as described above.

[0028] To further reduce light leakage, the recesses 62a may be subjected to at least one of light absorption treatment and surface roughening treatment. The light absorption treatment here refers to coloring the recesses 62a with paint of a color such as black or dark blue that has a higher light absorption than the color of the resin that constitutes the reflector 6. The surface roughening treatment refers to a treatment that forms fine irregularities on the surface that constitutes the recesses 62a by a known processing method such as embossing, sandblasting, or hairline finishing.

[0029] (Regarding the division structure of reflector 6) The plurality of second portions 62 of the reflector 6 include a specific portion 62D that is divided in the X direction (an example of the first direction) as shown in Fig. 2. That is, the reflector 6 of this embodiment is divided into left and right portions in Fig. 2 with the specific portion 62D as a boundary. By dividing the reflector 6 in this way, it is possible to prevent defects in the reflector 6, such as warping of the reflector 6 or peeling of the double-sided tape 7, due to a difference in the linear expansion coefficient between the circuit board 5 and the reflector 6.

[0030] Figure 8 is a cross-sectional view of the specific portion 62D of the reflector 6 taken along line III-III in Figure 2. Note that hatching indicating the cross section has been omitted in this cross-sectional view for ease of viewing (the same applies to Figures 9 and 10 described below). As shown in Figure 8, the specific portion 62D has a first adjacent portion 8 and a second adjacent portion 9 that are adjacent to each other with an interval in the X direction.

[0031] The first adjacent portion 8 has a first inner surface 81 facing the second adjacent portion 9 (facing the right in FIG. 8), and a first upper surface 82 connected to the upper end of the first inner surface 81. The first upper surface 82 is the surface facing the optical sheet 3 shown in FIG.

[0032] The second adjacent portion 9 has a second inner surface 91 facing the first inner surface 81 in the X direction, a second top surface 92 connected to the upper end of the second inner surface 91, and a bottom surface 93 connected to the lower end of the second inner surface 91. The second top surface 92 is the surface facing the optical sheet 3 shown in FIG.

[0033] The first upper surface 82 and the second upper surface 92 are parallel to each other and are positioned at the same height in the vertical direction. The other upper surfaces of the reflector 6 are also flush with the first upper surface 82 and the second upper surface 92. The optical sheet 3 is placed over the entire upper surface of the reflector 6.

[0034] The bottom surface 93 is located below the second top surface 92 and faces the optical sheet 3. From the viewpoint of efficiently reflecting light toward the optical sheet 3, as will be described later, the bottom surface 93 is preferably parallel to the first top surface 82 and the second top surface 92, but may be slightly inclined with respect to the first top surface 82 and the second top surface 92 as long as it can be considered to be roughly parallel.

[0035] As shown in FIG. 8 , the width of the bottom surface 93 in the X direction is greater than the distance between the first inner surface 81 and the second inner surface 82. The first adjacent portion 8 further includes a covering surface 83 that is connected to the lower end of the first inner surface 81 and covers a portion of the bottom surface 93 from above. In this embodiment, the covering surface 83 is inclined as shown in FIG. 8 . The second adjacent portion 9 includes an opposing surface that faces the covering surface 83 at a distance. The clearance between the first adjacent portion 8 and the second adjacent portion 9 is set as narrow as possible within a range that prevents the two from coming into contact due to vibration and thermal expansion. When the specific portion 62D configured in this manner is viewed from above as shown in FIG. 2 , the circuit board 5 is not visible in the area of ​​the specific portion 62D.

[0036] The specific portion 62D of the above structure allows light that is emitted from the light source 5a, reflected by the optical sheet 3, and enters the first inner surface 81 and the second inner surface 82 to be further reflected by the bottom surface 93 and directed toward the optical sheet 3. This makes it possible to suppress a decrease in the illumination brightness of the lighting device A, and as a result, to suppress a decrease in the display brightness of the liquid crystal panel 1. Furthermore, the specific portion 62D of the above structure makes it possible to suppress the light that enters the first inner surface 81 and the second inner surface 82 from leaking toward the circuit board 5, so that most of the light reflected by the bottom surface 93 can be directed toward the optical sheet 3.

[0037] The present invention is not limited to the above-described embodiments and drawings, and modifications (including the omission of components) can be made as appropriate within the scope of the present invention.

[0038] (Variation 1) As in a specific portion 62D according to Modification 1 shown in FIG. 9, the width of the bottom surface 93 in the X direction may be equal to the distance between the first inner side surface 81 and the second inner side surface 91.

[0039] (Variation 2) As in a specific portion 62D according to Modification 2 shown in Fig. 10, the first adjacent portion 8 and the second adjacent portion 9 may be combined with each other to form an L-shape in cross section. As shown in Fig. 10, the covering surface 83 may be a flat surface that covers a part of the bottom surface 93 from above.

[0040] (Other variations) The shape of the specific portion 62D is not limited to the examples shown in the above embodiment, Modification 1, and Modification 2. The shape of the specific portion 62D can be modified arbitrarily as long as it satisfies the following conditions: (i) a bottom surface 93 is formed in the specific portion 62D, (ii) the width of the bottom surface 93 in the X direction is equal to or greater than the distance between the first inner side surface 81 and the second inner side surface 91, and (iii) when the specific portion 62D is viewed from above as shown in FIG. 2 , the circuit board 5 is not visible in the area of ​​the specific portion 62D.

[0041] Although the above describes an example in which the X direction is the first direction and the Y direction is the second direction, the Y direction may be the first direction and the X direction may be the second direction. That is, the first portion 61 may extend in the Y direction and the second portion 62 may extend in the X direction. The first direction and the second direction do not need to be orthogonal to each other, as long as they intersect. That is, the surrounding wall 60 (and the dimming zone) of the reflector 6 is not limited to a square or rectangular shape, but may also be a rhombus or parallelogram shape. The display device 100 and the lighting device 2 are not limited to those mounted on vehicles, and may be used for various purposes.

[0042] Although the example in which the reflector 6 is divided into two has been described above, the reflector 6 may be divided into three or more parts.

[0043] In the above description, in order to facilitate understanding of the present disclosure, descriptions of well-known technical matters have been omitted as appropriate.

[0044] This invention allows various embodiments and modifications without departing from the broad spirit and scope of this invention. Furthermore, the above-described embodiments are intended to explain this invention and do not limit the scope of this invention. That is, the scope of this invention is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and the meaning of the invention equivalent thereto are considered to be within the scope of this invention. [Explanation of symbols]

[0045] 100…Display device 1...LCD panel A... Illumination device, 2... Illumination unit, 3... Optical sheet 4. Housing 5...Circuit board, 5a...Light source 6...Reflector, 7...Double-sided tape 60...Enclosure wall 61…Part 1 62…Second part 62D…Specific part 8...first adjacent portion, 81...first inner surface, 82...first upper surface, 83...covering surface 9...second adjacent portion, 91...second inner surface, 92...second upper surface, 93...bottom surface

Claims

1. a circuit board on which a plurality of light sources are mounted; an optical sheet that is opposed to the circuit board with a gap therebetween and has light-transmitting properties; a lattice-shaped reflector positioned between the circuit board and the optical sheet and surrounding each of the plurality of light sources, wherein the lighting device illuminates an object with the plurality of light sources controllable by local dimming, The reflector is a plurality of first portions arranged along a first direction and spaced apart in a second direction intersecting the first direction; a plurality of second portions arranged along the second direction and spaced apart in the first direction; the plurality of second portions include specific portions divided in the first direction, the specific portion includes a first adjacent portion and a second adjacent portion adjacent to each other with a gap in the first direction, the first adjacent portion has a first inner side surface facing the second adjacent portion and a first upper surface connected to an upper end of the first inner side surface and facing the optical sheet; the second adjacent portion has a second inner side surface facing the first inner side surface in the first direction, a second upper surface connected to an upper end of the second inner side surface and facing the optical sheet, and a bottom surface connected to a lower end of the second inner side surface and facing the optical sheet, a width of the bottom surface in the first direction that is equal to or greater than the distance between the first inner surface and the second inner surface; Lighting equipment.

2. a width of the bottom surface in the first direction is greater than a distance between the first inner surface and the second inner surface; The first adjacent portion further includes a covering surface that is connected to a lower end of the first inner surface and covers a portion of the bottom surface from above. The lighting device according to claim 1 .

3. 3. A lighting device comprising: the lighting device according to claim 1 or 2; and a liquid crystal panel as the target. Display device.

Images