Illumination device and display device

Abstract

To provide a lighting device capable of excellently radiating heat from a driver while excellently illuminating an object, and a display device equipped with the same.SOLUTION: The lighting device 2 includes a circuit substrate 5 having a front surface on which a plurality of light sources 5a are mounted and a rear surface on which a driver 5b for driving one or more light sources 5a among the plurality of light sources 5a is mounted, a lattice-shaped reflector 6 surrounding each of the plurality of light sources 5a, a metallic case 8 recessed rearward from a top surface 81 and having a recess 82 provided corresponding to the driver 5b, a first heat-conducting T1 in contact with the rear surface of the circuit substrate 5 and the top surface 81, and a second heat-conducting 5b in contact with the driver 82a and a bottom wall of the recess 82. T2. In the circuit substrate 5, a hole 5H through which the internal space Si of the recess 82 and the front space Sf of the circuit substrate 5 communicate with each other is formed at a position covered with the reflector 6.SELECTED DRAWING: Figure 5

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 capable of controlling the lighting of multiple light sources mounted on the front surface of a circuit board and illuminating 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 device, a grid-shaped reflector is provided on the front of the circuit board, surrounding each of the multiple light sources (i.e., defining a dimming zone). Drivers for driving the light sources are typically mounted on the back of the circuit board. This type of device requires a structure that can dissipate heat generated by the drivers without interfering with the ability to effectively illuminate an object such as an LCD panel.

[0005] The present disclosure has been made in consideration of the above-mentioned situation, and aims to provide a lighting device that can effectively illuminate an object while effectively dissipating heat from a driver, and a display device equipped with the same. [Means for solving the problem]

[0006] In order to achieve the above object, a lighting device according to a first aspect of the present disclosure comprises: a circuit board having a front surface and a rear surface, with a plurality of light sources mounted on the front surface and a driver mounted on the rear surface for driving one or more of the plurality of light sources; a lattice-shaped reflector located in front of the circuit board and surrounding each of the plurality of light sources; a metal housing located behind the circuit board, the metal housing having a top surface facing the back surface, and a recess recessed rearward from the top surface and provided to correspond to the driver; a first thermally conductive portion located between the rear surface and the top surface and in contact with the rear surface and the top surface; a second thermally conductive portion located between the driver and a bottom surface of the recess and in contact with the driver and the bottom surface; An illumination device that illuminates an object using the plurality of light sources that can be controlled by local dimming, The circuit board has a hole that communicates the internal space of the recess with a space in front of the circuit board, the hole being formed at a position that is covered by the reflector.

[0007] 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]

[0008] The present disclosure provides good illumination of the object while also providing good heat dissipation from the driver. [Brief explanation of the drawings]

[0009] [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 lighting device 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 lighting device according to the embodiment taken along line II-II in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present disclosure will be described with reference to the drawings.

[0011] The display device 100 shown in Fig. 1 includes a liquid crystal panel 1, an illumination device 2 (backlight unit) that illuminates the liquid crystal panel 1 from behind, an optical sheet 3 provided between the liquid crystal panel 1 and the illumination device 2, 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 optical sheet 3 is a diffusion plate or the like. The display device 100 is, for example, a meter provided on an instrument panel of a vehicle.

[0012] 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 Z axis is along the vertical direction in FIG. 1. 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 front of the display device 100, and the -Z direction is the rear of the display device 100. The surface facing the rear of a certain component is called the back surface.

[0013] As shown in appropriate views of Figures 2 to 5, the lighting device 2 includes a circuit board 5, a reflector 6, double-sided tape 7, a metal housing 8, a first heat conductive member T1, and a second heat conductive member T2.

[0014] The circuit board 5 is a PCB (Printed Circuit Board) and has a front surface and a back surface parallel to the XY plane. A plurality of light sources 5a are mounted on the front surface of the circuit board 5 and arranged in the X and Y directions. For example, the light sources 5a are LEDs (Light-Emitting Diodes). As shown in FIGS. 3 and 5, a driver 5b for driving one or more of the plurality of light sources 5a is mounted on the back surface of the circuit board 5. The driver 5b is an LED driver integrated circuit (IC), and although not shown, a plurality of drivers 5b are provided corresponding to the light sources 5a to be driven. As shown in FIGS. 4 and 5, a hole 5H, which will be described later, is formed in the circuit board 5.

[0015] The light emission of the multiple light sources 5a is controlled by local dimming via a driver 5b under the control of a control unit (not shown). 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.

[0016] The reflector 6 is located in front of the circuit board 5 and is formed in a grid shape surrounding each of the multiple light sources 5a. The reflector 6 is formed, for example, from a white resin. As shown in FIG. 2 , of the grid-shaped reflector 6, a portion extending in the X direction is defined as a first portion 61, and a portion located between adjacent first portions 61 is defined as a second portion 62 extending in the Y direction. In other words, the reflector 6 has the first portion 61 and the second portion 62.

[0017] Specifically, the first portions 61 extend in the X direction (an example of a first direction) and are arranged at intervals in the Y direction (an example of a second direction). The second portions 62 are located between adjacent first portions 61, extend in the Y direction, and are arranged at intervals in the X direction.

[0018] Here, adjacent first portions 61 and adjacent second portions 62 between them form one surrounding wall 60 that surrounds one light source 5a (see the dashed line in FIG. 2). In other words, the surrounding wall 60 defines a dimming zone. 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 for each dimming zone toward the liquid crystal panel 1.

[0019] 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.

[0020] 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 on 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.

[0021] As shown in FIGS. 3 and 5, the metal housing 8 is located behind the circuit board 5. The metal housing 8 has a top surface 81 facing the back surface of the circuit board 5, a recess 82 recessed rearward from the top surface 81 and provided to correspond to the driver 5b, and a heat sink 83 (see FIG. 5). The recess 82 is provided to avoid the driver 5b protruding rearward from the circuit board 5. The heat sink 83 is formed in a comb-like or fin-like shape protruding rearward from the metal housing 8. The metal housing 8 may be formed integrally with the housing 4 of the display device 100.

[0022] 3 and 5 conducts heat from the circuit board 5 to the metal housing 8. The first heat conductive part T1 is located between the rear surface of the circuit board 5 and the top surface 81 of the metal housing 8, and is in contact with the rear surface of the circuit board 5 and the top surface 81 of the metal housing 8. The first heat conductive part T1 is, for example, thermal tape (thermally conductive double-sided tape).

[0023] 3 and 5 conducts heat from the driver 5b to the metal housing 8. The second heat conductive portion T2 is located between the driver 5b and the bottom surface 82a of the recess 82 and is in contact with the driver 5b and the bottom surface 82a. The second heat conductive portion T2 is, for example, thermal paste (heat dissipation grease).

[0024] If no measures are taken, the internal space Si of the recess 82 will be sealed by the circuit board 5 and the first heat-conducting part T1. If this happens, when the air in the internal space Si expands due to the heat of the driver 8b, there is a risk that the circuit board 5 will peel off from the metal casing 8. To solve this problem, a hole 5H is formed in the circuit board 5.

[0025] 5, the hole 5H formed in the circuit board 5 communicates the internal space Si of the recess 82 with the front space Sf of the circuit board 5. This allows heat from the driver 5b to be efficiently released.

[0026] Moreover, the holes 5H are formed at positions that are covered by the reflector 6. This prevents light emitted from the light source 5a and reflected by the optical sheet 3 or the reflector 6 from leaking behind the circuit board 5. As a result, it is possible to prevent a reduction in the light illuminating the target (liquid crystal panel 1), and to illuminate the target well.

[0027] Specifically, the holes 5H are formed at positions covered by the second portion 62 of the reflector 6. Furthermore, the holes 5H are formed between the light sources 5a adjacent to each other in the X direction (an example of the first direction) among the plurality of light sources 5a. This allows the holes 5H to be provided at locations on the front surface of the circuit board 5 where no double-sided tape 7 is present, allowing efficient exchange of air between the internal space Si and the front space Sf.

[0028] 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.

[0029] 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.

[0030] The first thermally conductive part T1 and the second thermally conductive part T2 are not limited to the above examples and may be any. For example, if there is a means for fixing the circuit board 5 to the metal casing 8, the first thermally conductive part T1 may be thermal paste. The second thermally conductive part T2 may be thermal tape.

[0031] Furthermore, a recess that is recessed in a direction away from the circuit board 5 (+Z direction) may be formed on the surface of the second portion 62 facing the circuit board 5. When the reflector 6 is viewed in a cross section similar to that of FIG. 5, this recess may be V-shaped, concavely curved, W-shaped, or the like. By providing such a recess 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 and the circuit board 5. Therefore, the amount of light leakage from one dimming zone to the other dimming zone of light sources 5a adjacent to each other in the X direction is effectively reduced.

[0032] To further reduce light leakage, the recesses 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 with a 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 by a known processing method such as embossing, sandblasting, or hairline finishing.

[0033] In the above description, in order to facilitate understanding of the present disclosure, descriptions of well-known technical matters have been omitted as appropriate.

[0034] 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]

[0035] 100…Display device 1...LCD panel 2...Lighting equipment 3...Optical sheet 4. Housing 5...circuit board, 5a...light source, 5b...driver, 5H...hole 6...reflector, 60...enclosure wall, 61...first portion, 62...second portion 7...Double-sided tape 8...metallic housing, 81...top surface, 82...recess, 82a...bottom surface, 83...heat sink T1: First heat conduction section, T2: Second heat conduction section Si...Internal space, Sf...Front space

Claims

1. a circuit board having a front surface and a rear surface, with a plurality of light sources mounted on the front surface and a driver mounted on the rear surface for driving one or more of the plurality of light sources; a lattice-shaped reflector located in front of the circuit board and surrounding each of the plurality of light sources; a metal housing located behind the circuit board, the metal housing having a top surface facing the back surface, and a recess recessed rearward from the top surface and provided to correspond to the driver; a first thermally conductive portion located between the rear surface and the top surface and in contact with the rear surface and the top surface; a second heat conductive portion located between the driver and a bottom surface of the recess and in contact with the driver and the bottom surface; An illumination device that illuminates an object using the plurality of light sources that can be controlled by local dimming, a hole communicating an internal space of the recess with a front space of the circuit board is formed in the circuit board at a position covered by the reflector; Lighting equipment.

2. a double-sided tape for fixing the reflector to the front surface of the circuit board; The reflector is a plurality of first portions extending in a first direction and arranged at intervals in a second direction intersecting the first direction; a plurality of second portions positioned between adjacent first portions, extending in the second direction, and arranged at intervals in the first direction; the double-sided tape has a strip shape extending in the first direction and is positioned between the first portion and the circuit board; The hole is formed at a position covered by the second portion. The lighting device according to claim 1 .

3. the holes are formed between adjacent light sources in the first direction among the plurality of light sources; 3. The lighting device according to claim 2.

4. The lighting device according to any one of claims 1 to 3 and a liquid crystal panel as the target. Display device.

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