JP2024066191A - Illumination device and display device - Google Patents

Abstract

[Problem] To improve reliability when used at high temperatures while reducing the thickness and narrowing the frame. [Solution] A lighting device 30 includes a light source 35, a light guide plate 40 that guides light from the light source 35, an optical sheet 45 that is arranged to cover a light output main surface 40B of the light guide plate 40 and imparts an optical effect to the light from the light guide plate 40, and a frame 60 that is arranged on the opposite side of the optical sheet 45 to the light guide plate 40 and overlaps with at least a part of an outer circumferential edge portion 40B1 of the light output main surface 40B of the light guide plate 40. The light guide plate 40 has a protrusion 41A at a position on the light output main surface 40B where it overlaps with the frame 60. The optical sheet 45 has an insertion hole 45A into which the protrusion 41A is inserted. The frame 60 has a through hole 61A1 at a position where it overlaps with the protrusion 41A. An intervening portion 62 for suppressing contact with the optical sheet 45 is provided on a surface 62A2 of the frame 60 facing the optical sheet 45 at a position not overlapping with the through hole 61A1.

Description

The technology described in this specification relates to lighting devices and display devices.

Conventionally, there is known a liquid crystal display device that has a light guide plate on the back side of the liquid crystal panel. In this liquid crystal display device, light from a light source is incident on the light guide plate, propagates inside the light guide plate, and is emitted towards the liquid crystal panel side. It is also known that an optical sheet that imparts a predetermined optical effect is disposed on the front side (liquid crystal panel side) of the light guide plate, and an example of this is disclosed in Patent Document 1.

The light guide plate and optical sheet described in Patent Document 1 have protrusions formed on their respective sides. In addition, the frame of the housing that holds them has recesses formed into which the protrusions fit. It is said that the provision of the protrusions and recesses makes it possible to position the light guide plate and optical sheet.

JP 2003-66420 A

However, as described above, forming the protrusions and recesses makes it difficult to narrow the frame of the backlight device. Also, when the backlight device is made thinner, it becomes difficult to ensure the thickness required to form the recesses in the frame. As a solution, it is possible to form protrusions in the frame area (non-display area) of the main surface of the light guide plate and to form insertion holes for the protrusions in the optical sheet. However, in that case, if the operating environment temperature becomes high and the light guide plate expands, the protrusions of the light guide plate may come into contact with the frame, causing cracks at the base of the protrusions and reducing reliability. Also, if a clearance space is secured to prevent the protrusions from breaking and reliability is increased, it becomes difficult to make the backlight device thinner.

The technology described in this specification was developed based on the above-mentioned circumstances, and aims to improve reliability when used at high temperatures while reducing thickness and narrowing the frame.

(1) The lighting device according to the present technology includes a light source, a light guide plate that guides light from the light source, the light guide plate having a light exiting main surface from which the light is emitted, an optical sheet that is arranged to cover the light exiting main surface and that imparts an optical effect to the light from the light guide plate, and a frame that is arranged on the side of the optical sheet opposite the light guide plate and overlaps at least a portion of the outer periphery of the light exiting main surface of the light guide plate, the light guide plate having a protrusion at a position where the light exiting main surface overlaps with the frame, the optical sheet having an insertion hole into which the protrusion is inserted, the frame having a through hole at a position where the protrusion overlaps with the frame, and an interposition portion for suppressing contact with the optical sheet is provided on the surface of the frame facing the optical sheet at a position where the frame does not overlap with the through hole.

(2) In addition to the above (1), the lighting device may also be configured such that the interposition portion is provided around the through hole.

(3) In addition to the above (2), the lighting device may have a plurality of the intervening portions, and at least two of the intervening portions may be opposed to each other across the through hole.

(4) In addition to the above (1), the interposition portion may surround the outer periphery of the through hole.

(5) In addition to the above (1), the interposition portion of the lighting device may include a first interposition portion provided around the through hole and a second interposition portion provided along the extension direction of the frame.

(6) In addition to any one of (1) to (5) above, the lighting device may also be configured such that the through hole is substantially located at the center of the extension direction of the frame.

(7) In addition to any one of (1) to (6) above, the lighting device may have a plurality of the insertion holes, and the through hole may overlap one of the plurality of insertion holes.

(8) In addition to any one of (1) to (7) above, the lighting device may also be such that the interposition portion is integrally formed with the frame.

(9) In addition to any one of (1) to (7) above, the lighting device may also be configured such that the interposition portion is made of a material different from that of the frame.

(10) A display device according to the present technology includes any one of the illumination devices (1) to (9) above and a display panel onto which light from the illumination device is irradiated.

(11) In addition to the above (10), the display panel of the display device may be a liquid crystal panel.

This technology makes it possible to reduce the thickness and frame while improving reliability when used at high temperatures.

1 is a schematic diagram of a liquid crystal display device according to a first embodiment of the present invention; A plan view of the backlight device from the front side. Cross-sectional view of line II in FIG. Plan view of the light guide plate from the front side FIG. 3 is an enlarged perspective view of the vicinity of a through hole of the frame shown in FIG. Plan view of the long side of the frame from the back A perspective view of the through-hole of the frame seen from the back side FIG. 3 is an enlarged plan view of the vicinity of the through hole of the frame of FIG. 8, line II-II cross-sectional view. FIG. 11 is a perspective view of the vicinity of the through-hole of the frame according to the second embodiment, viewed from the back side; FIG. 11 is a plan view of the long side of the frame according to the third embodiment, viewed from the back side.

<Embodiment 1>
A first embodiment will be described with reference to Fig. 1 to Fig. 9. In this embodiment, a liquid crystal display device (an example of a display device) 100 equipped with a backlight device 30 (an example of an illumination device) is illustrated. Note that an X-axis, a Y-axis, and a Z-axis are shown in some of the drawings, and each axis direction is drawn to be a common direction in each drawing. In addition, in the Z-axis direction, the liquid crystal panel 10 side is the front side, and the backlight device 30 side is the back side.

As shown in FIG. 1, the liquid crystal display device 100 includes a liquid crystal panel 10 (an example of a display panel) capable of displaying an image on a display surface 10S, and a backlight device 30 (an example of a lighting device) disposed on the rear side of the liquid crystal panel 10 (the side opposite the display surface 10S) and irradiating light onto the liquid crystal panel 10. A control board 16 that supplies signals and the like required for image display is connected to the liquid crystal panel 10 via a flexible board 14, which is a flexible wiring board.

The liquid crystal panel 10 is divided into a display area (active area) AA, which is capable of displaying an image and is located at the center, and a non-display area (non-active area) NAA, which is located on the outer periphery of the display area AA and has a frame-like (picture frame-like) shape in a plan view. In FIG. 1, the dashed line represents the outer shape of the display area AA, and the area outside the dashed line is the non-display area NAA. The liquid crystal panel 10, backlight device 30, and liquid crystal display device 100 are generally rectangular with a long side and a long side aligned with the X-axis direction, a short side aligned with the Y-axis direction, and a thickness aligned with the Z-axis direction in each drawing, but the shape and size are not limited.

2 and 3, the backlight device 30 includes a plurality of LEDs 35 (an example of a light source), a light guide plate 40, an optical sheet 45, a reflective sheet 50, a tray-shaped chassis 55, and a frame-shaped frame 60. The backlight device 30 is an edge light type in which the light of the LEDs 35 is incident only from one long end surface 40A (an example of an incident surface) of the light guide plate 40. However, the backlight device 30 may be a double-sided light-input type in which the light of the LEDs 35 is incident from both long end surfaces of the light guide plate 40 (i.e., the LEDs 35 are arranged along both long end surfaces of the light guide plate 40), or may be configured to be incident from the short end surface of the light guide plate 40 (i.e., the LEDs 35 are arranged along the short end surface of the light guide plate 40). The backlight device 30 may also be a direct type in which the LEDs 35 are arranged on the back side of the light guide plate 40. In this embodiment, a configuration in which light from the LEDs 35 is incident on the long side surface 40A of the light guide plate 40 is illustrated.

As shown in FIG. 3, the chassis 55 is shaped like a tray that opens toward the front side (the liquid crystal panel 10 side). The chassis 55 is made of a material with excellent rigidity, such as metal. The bottom portion 55A of the chassis 55 houses the LEDs 35, the light guide plate 40, the optical sheet 45, and the reflective sheet 50.

As shown in Figs. 2 and 3, the frame 60 is, for example, a horizontally elongated rectangular frame in a plan view, and is made of resin. The frame 60 is fitted into the chassis 55. The LEDs 35, the light guide plate 40, the optical sheet 45, and the reflective sheet 50 are sandwiched between the frame 60 and the chassis 55. The frame 60 will be described in detail later.

The LEDs 35 are arranged along the incident end surface 40A of the light guide plate 40. The LEDs 35 are mounted on an LED board extending along the incident end surface 40A of the light guide plate 40. The LEDs 35 are rectangular parallelepipeds, with one side serving as the light-emitting surface, so-called side-emitting type (side-view type). The optical axis of the LEDs 35 (the light traveling direction in which the emitted light has the highest peak intensity) is the Y-axis direction. The LEDs 35 may be of a monochromatic emission type or a white (mixed light) emission type. When the LEDs 35 are of a monochromatic emission type, they may be combined with a wavelength conversion member to emit white light to the liquid crystal panel 10. For example, a wavelength conversion sheet may be used for at least one of the optical sheets 45.

The light guide plate 40 guides the light from the LEDs 35. More specifically, the light guide plate 40 introduces the light emitted from the LEDs 35 from the incident end surface 40A and propagates the light inside along the Y-axis direction. The light guide plate 40 also propagates the light in the Y-axis direction, while raising it so that it faces the front side and emits it from the light output main surface 40B (the main surface on the front side). The light guide plate 40 is made of a resin (e.g., polycarbonate) that has a refractive index sufficiently higher than that of air and is highly transparent. The light guide plate 40 is a thick flat plate compared to the optical sheet 45.

As shown in FIG. 4, the light guide plate 40 has three protrusions 41 along one long side of the outer peripheral edge 40B1 of the light output main surface 40B. The protrusions 41 are provided to position and engage the optical sheet 45 placed on the light guide plate 40. The protrusions 41 are integrally provided on the light guide plate 40, and are integrally formed, for example, by injection molding a resin material. Although at least one protrusion 41 is sufficient to engage the optical sheet 45, it is preferable to provide multiple protrusions in order to position the optical sheet 45. In addition, since the protrusions 41 are inserted into the insertion holes 45A of the optical sheet 45 described later, it is preferable that the protrusion length is equal to or greater than the thickness of the optical sheet 45 (the total thickness when multiple sheets are used).

The outer peripheral edge 40B1 of the light-emitting principal surface 40B of the light guide plate 40 overlaps with the non-display area NAA of the liquid crystal panel 10 and the main body portion 61 of the frame 60, which will be described later. The outer peripheral edge 40B1 of the light-emitting principal surface 40B is covered from the front side by the main body portion 61, and the protrusions 41 overlap with one long side portion 61A of the main body portion 61. The protrusions 41 are arranged at intervals in the extension direction (X-axis direction) of the long side portion 61A. The protrusions 41 include a first protrusion 41A that is arranged at a substantial center position in the extension direction of the long side portion 61A, and second protrusions 41B, 41C that are arranged at positions near both ends of the long side portion 61A. The first protrusion 41A overlaps with a through hole 61A1 (described later) of the frame 60 and is open on the front side, while the second protrusions 41B and 41C are covered on the front side by the long side 61A of the frame 60.

The optical sheet 45 imparts a predetermined optical effect to the light emitted from the light guide plate 40. As shown in FIG. 3, the optical sheet 45 is installed on the light output main surface 40B of the light guide plate 40 so as to cover the light output main surface 40B. Various types of optical sheets 45 are known, and one or more types are used depending on the application. For example, the optical sheet 45 is a resin light diffusion sheet, a prism sheet, a lens sheet, a brightness improvement sheet, or a wavelength conversion sheet. When multiple optical sheets 45 are used, they are stacked and installed on the light output main surface 40B. The optical sheet 45 has insertion holes 45A into which the protrusions 41 of the light guide plate 40 are inserted. The number of insertion holes 45A corresponds to the number of the protrusions 41. In this embodiment, as described above, three protrusions 41 are provided (first protrusion 41A, second protrusion 41B, 41C), and one insertion hole 45A is provided for each protrusion 41, for a total of three.

The reflection sheet 50 is disposed on the rear side of the light guide plate 40 (the side opposite to the light output main surface 40B) and reflects the light leaking from the light guide plate 40 toward the light guide plate 40. The reflection sheet 50 is a sheet-like member whose surface has excellent light reflectivity. There are many different types of reflection sheets 50 known, and one example is a sheet-like member made of white resin.

As shown in Figs. 2 and 3, the frame 60 has a main body 61, a side portion 65, and an extension portion 67. The main body 61 is a portion that overlaps with the outer peripheral edge portion 40B1 of the light-emitting main surface 40B of the light guide plate 40, the outer peripheral edge portion of the optical sheet 45, and the non-display area AA of the liquid crystal panel 10. The side portion 65 is a portion that falls from the outer peripheral end of the main body 61 to the back side. The side portion 65 covers the side wall 55B of the chassis 55 from the outside (the side opposite to the inside of the chassis 55). The extension portion 67 rises from the main body 61 to the front side, bends, and extends outward. The extension portion 67 is a portion that engages with a bezel (frame) that is provided on the front side of the liquid crystal panel 10 and forms the appearance of the front side of the liquid crystal display device 100.

As shown in Figs. 2 to 3 and 5 to 8, a through hole 61A1 is provided in one long side 61A of the main body 61 of the frame 60. One through hole 61A1 is provided at a substantial center position in the extension direction (X-axis direction) of one long side 61A. The through hole 61A1 overlaps with the first protrusion 41A of the light guide plate 40. The through hole 61A1 also overlaps with the insertion hole 45A of the optical sheet 45 into which the first protrusion 41A is inserted. The through hole 61A1 has a planar size larger than the first protrusion 41A, and is formed in a planar shape (in this embodiment, a horizontally elongated ellipse) that imitates the first protrusion 41A.

The through hole 61A1 allows the first protrusion 41A to extend through the through hole 61A1 when the ambient temperature becomes high and the light guide plate 40 expands. At high temperatures, the light guide plate 40 is more likely to expand so that the long sides are curved and warped than the short sides, and the area near the center of the long sides is most likely to displace toward the front side. Therefore, the through hole 61A1 is formed at a position that overlaps with the first protrusion 41A, which has the largest amount of displacement due to temperature change, among the protrusions 41. However, the through hole 61A1 may also be formed at a position that overlaps with the second protrusions 41B and 41C.

As shown in Figs. 6 to 9, the back surface 61A2 (the surface facing the optical sheet 45) of the long side portion 61A of the frame 60 is provided with an intervening portion 62 that protrudes to the back side so as to be interposed between the optical sheet 45 and the back surface 61A. The intervening portion 62 is integrally provided with the frame 60, and is formed integrally with the resin frame 60 by, for example, injection molding. The intervening portion 62 is provided to prevent damage such as scraping of the optical sheet 45 due to contact with the back surface 61A2. The intervening portion 62 is provided at a position that does not overlap with the insertion hole 45A of the optical sheet 45 and the through hole 61A1 of the frame 60 so as to be interposed between the optical sheet 45 and the back surface 61A2.

As shown in FIG. 6, the interposition portion 62 includes a first interposition portion 62A provided around the through hole 61A1 and a second interposition portion 62B provided along the extension direction (X-axis direction) of the long side portion 61A. Two first interposition portions 62A are provided with a gap in the Y-axis direction so as to form a pair on either side of the through hole 61A1. In addition to preventing damage to the optical sheet 45 as described above, the first interposition portion 62A can compensate for the reduction in strength around the through hole 61A1 due to the formation of the through hole 61A1. By providing two first interposition portions 62A as a pair on either side of the through hole 61A1, the strength can be effectively reinforced.

The second intermediate portion 62B is provided in a plurality (four in this embodiment) on the back surface 61A2 of the long side portion 61A. More specifically, two second intermediate portions 62B are provided with a gap between the first intermediate portion 62A and one end 61A3 (see FIG. 2) of the long side portion 61A. Two second intermediate portions 62B are provided with a gap between the first intermediate portion 62A and the other end 61A4 of the long side portion 61A. By providing the second intermediate portions 62B in this manner, the optical sheet 45 can be made to be non-contact over the entire long side portion 61A. The first intermediate portion 62A and the second intermediate portion 62B do not need to have the same shape (in this embodiment, a horizontally elongated ellipse in a plan view) and size, and may be different from each other.

Next, the action and effect of the backlight device 30 described above will be explained. The light guide plate 40 and the optical sheet 45 are aligned by inserting the first protrusion 41A of the light guide plate 40 into the insertion hole 45A of the optical sheet 45. Since the first protrusion 41A is provided on the light-emitting main surface 40B, the frame area of the backlight device 30 does not expand to form the first protrusion 41A, and the frame can be narrowed. The frame 60 also has a through hole 61A1 that overlaps with the first protrusion 41A. When the light guide plate 40 expands during use at high temperatures, the first protrusion 41A expands through the through hole 61A1. The first protrusion 41A does not come into contact with the main body 61 of the frame 60 and is not damaged. As a result, there is no need to secure a clearance space to prevent the first protrusion 41A from being damaged, and the device can be made thinner. However, providing the through hole 61A1 in this manner raises the concern that the optical sheet 45 between the light guide plate 40 and the main body 61 may come into contact with the main body 61 (more specifically, the back surface 61A2) and be scraped off when the light guide plate 40 expands. Therefore, in this embodiment, the interposition portion 62 is provided in the frame 60 to prevent such damage to the optical sheet 45. As a result, the backlight device 30 can be made thinner and have a narrower frame, while preventing damage to the light guide plate 40 and the optical sheet 45 when used at high temperatures, thereby improving reliability.

<Embodiment 2>
A first intermediate portion 162A according to the second embodiment will be described with reference to Fig. 10. In the second embodiment, the same configuration, action, and effect as those of the first embodiment will not be described repeatedly.

The first intermediate portion 162A surrounds the entire outer circumference of the through hole 61A1 and is formed into a horizontally elongated ellipse in a plan view. The first intermediate portion 162A can more effectively reinforce the strength reduction caused by the formation of the through hole 61A1.

<Embodiment 3>
The second intermediate portion 162B according to the third embodiment will be described with reference to Fig. 11. In the third embodiment, the same configurations, actions, and effects as those in the first and second embodiments will not be described again.

The second intermediate portion 162B has a different shape from the second intermediate portion 62B in embodiment 1, and is a horizontally long rod that runs along one of the long sides 61A of the main body portion 61. The second intermediate portion 162B may be realized as a separate body from the main body portion 61 using a flexible cushioning material or the like. In this way, the second intermediate portion 162B can be easily provided using a tape-like member or the like that has cushioning properties.

<Other embodiments>
The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included within the technical scope of the present invention.

(1) The overall shapes of the chassis 55 and the frame 60 are not limited to those shown in the figure, and can be modified as appropriate as long as the LEDs 35, the light guide plate 40, the optical sheet 45, and the reflective sheet 50 can be sandwiched between them. For example, the frame 60 is not limited to a frame shape, and may have a shape that covers part of the outer peripheral edge portion 40B1 of the main light-emitting surface 40B of the light guide plate 40 from the front side. In addition, the chassis 55 and the frame 60 do not need to be directly fitted together, and the two may be fixed together by other members.

10...Liquid crystal panel (display panel), 30...Backlight device (illumination device), 35...LED (light source), 40...Light guide plate, 40B...Light output surface, 40B1...Outer periphery, 41A...First protrusion (protrusion), 45...Optical sheet, 45A...Insertion hole, 60...Frame, 61A1...Through hole, 62A2...Back surface (opposing surface), 62...Interposition, 62A, 162A...First interposition (interposition), 62B, 162B...Second interposition (interposition), 100...Liquid crystal display device (display device)

Claims (11)

A light source;
a light guide plate for guiding light from the light source, the light guide plate having a light exiting main surface from which the light exits;
an optical sheet arranged to cover the light exiting main surface and imparting an optical effect to the light from the light guide plate;
a frame disposed on a side of the optical sheet opposite the light guide plate and overlapping at least a portion of an outer periphery of the light output main surface of the light guide plate,
the light guide plate has a protrusion at a position on the light output main surface where the light guide plate overlaps with the frame,
the optical sheet has an insertion hole into which the protrusion is inserted,
the frame has a through hole at a position where the frame overlaps with the protrusion,
An illumination device in which an intervening portion for suppressing contact with the optical sheet is provided on the surface of the frame facing the optical sheet at a position not overlapping with the through hole. The lighting device according to claim 1, wherein the interposition portion is provided around the through hole. The lighting device according to claim 2, wherein a plurality of the intervening parts are provided, and at least two of the intervening parts face each other across the through hole. The lighting device according to claim 1, wherein the interposition portion surrounds the outer periphery of the through hole. The lighting device according to claim 1, wherein the interposition portion includes a first interposition portion provided around the through hole and a second interposition portion provided along the extension direction of the frame. The lighting device according to any one of claims 1 to 5, wherein the through hole is provided at a substantially central position in the extension direction of the frame. The insertion hole is provided in plurality,
The lighting device according to claim 1 , wherein the through hole overlaps one of the plurality of insertion holes. The lighting device according to any one of claims 1 to 5, wherein the interposition portion is integrally provided on the frame. The lighting device according to any one of claims 1 to 5, wherein the interposition portion is made of a material different from that of the frame. The lighting device according to any one of claims 1 to 5,
a display panel onto which light from the illumination device is irradiated. The display device according to claim 10, wherein the display panel is a liquid crystal panel.

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