WO2017061114A1

WO2017061114A1 - Liquid crystal display device

Info

Publication number: WO2017061114A1
Application number: PCT/JP2016/004486
Authority: WO
Inventors: 佐藤　弘章
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2015-10-08
Filing date: 2016-10-05
Publication date: 2017-04-13
Also published as: JP2017072837A; JP6715457B2

Abstract

This liquid crystal display device has: a liquid crystal panel having a curved shape; and an edge-light-type backlight that has a light source and a light guide plate, and that emits light from a rear surface of the liquid crystal panel. The light guide plate has: a main surface section formed in the same curved shape as the liquid crystal panel; and a curved edge section that extends in a curve from the main surface section. The light source has a plurality of light-emitting elements that are disposed so as to face an end surface of the curved edge section.

Description

Liquid crystal display

The present invention relates to a liquid crystal display device having a curved display surface.

Conventionally, a liquid crystal display device having a liquid crystal panel on the front side and a backlight on the back side is known. The backlight is a planar light emitting device that emits light from the back side to the liquid crystal panel. Usually, an edge-light type backlight includes an optical sheet such as a reflector, a light guide plate (LGP), and a diffusion sheet, and a white LED (Light Emitting Diode) that allows light to enter from the side of the light guide plate. A light source. These are arranged in order from the back side.

As a liquid crystal display device, a flat panel display having a flat liquid crystal panel is generally used. In recent years, a liquid crystal display device having a liquid crystal panel whose display surface is curved in a convex shape or a concave shape has been required in terms of design, and has been put into practical use (for example, Patent Documents 1 and 2). Patent Document 1 discloses an edge-light type backlight in which a light source is disposed so as to face a short side surface (a non-curved side surface) of a light guide plate that is concavely curved on the display surface side. Patent Document 2 discloses an edge-light type backlight in which a light source is disposed so as to face a side surface (curved side surface) on the long side of a light guide plate that is convexly curved toward the display surface side. Yes.

Japanese Patent No. 4980425 JP 2001-356342 A

The present invention is a liquid crystal display device having a curved display surface. This liquid crystal display device can reliably make the light from the light source incident on the light guide plate regardless of the curved shape of the light guide plate or the frame, and can prevent the occurrence of uneven brightness.

The liquid crystal display device according to the present invention includes a liquid crystal panel and an edge light type backlight. The liquid crystal panel has a curved shape, a display surface, and a back surface on the back side of the display surface. The backlight includes a light source and a light guide plate, and is arranged to irradiate light from the back surface of the liquid crystal panel. The light guide plate has a main surface portion having a curved shape similar to that of the liquid crystal panel, and a bent edge portion that is bent and extends from the main surface portion. The light source has a plurality of light emitting elements arranged to face the end surface of the bent edge.

According to the present invention, the light source can be easily opposed to the side surface of the light guide plate regardless of the curved shape of the light guide plate or frame, so that the light from the light source reliably enters the light guide plate. Accordingly, it is possible to prevent occurrence of luminance unevenness in the liquid crystal display device.

FIG. 1 is a perspective view showing a liquid crystal display device according to the first embodiment. FIG. 2 is a partial cross-sectional view showing the internal structure of the liquid crystal display device shown in FIG. FIG. 3 is a diagram showing the positional relationship between the light guide plate and the light source in the liquid crystal display device shown in FIG. FIG. 4 is a perspective view showing a liquid crystal display device according to the second embodiment. FIG. 5 is a cross-sectional view showing the internal structure of the liquid crystal display device shown in FIG. 6 is a diagram showing the positional relationship between the light guide plate and the light source in the liquid crystal display device shown in FIG.

Prior to the description of the embodiments of the present invention, problems in the conventional liquid crystal display device will be briefly described. As described above, when an edge light type backlight is employed in a liquid crystal display device having a curved display surface, there are the following problems. In other words, the curved surface (curvature radius) of the light guide plate or the frame to which the light guide plate is bonded is not constant due to tolerances. Therefore, it is difficult to face the LED directly to the side surface of the light guide plate, and light from the LED may come off from the light guide plate, which may cause uneven brightness.

Further, in the case of the backlight described in Patent Document 1, LEDs that are light sources are arranged along the short sides of the light guide plate. For this reason, the number of LEDs is reduced as compared with the case where the light source is arranged along the long side, and the luminance may be insufficient. Further, a driving IC (Integrated Circuit) for driving the liquid crystal panel is disposed on a flat edge on the short side of the liquid crystal panel. For this reason, the LED is disposed in the vicinity of the driving IC, and there is a concern that the rise in the component temperature is promoted.

On the other hand, in the case of the backlight described in Patent Document 2, LEDs are arranged along the long side of the light guide plate that is curved. Therefore, a flexible printed circuit board (FPC: Flexible printed circuit) on which an LED is mounted is attached while being curved in the edgewise direction. With this structure, it is difficult to ensure the positional accuracy of the LED, and it is also difficult to fix the FPC on which the LED is mounted to the frame.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a perspective view showing a liquid crystal display device 1 according to a first embodiment of the present invention. FIG. 2 is a partial cross-sectional view showing the internal structure of the liquid crystal display device 1. FIG. 3 is a diagram illustrating a positional relationship between the light guide plate 122 and the light source 124 in the liquid crystal display device 1. 2 shows an enlarged cross section of a portion A surrounded by a broken line in FIG.

The liquid crystal display device 1 is a vehicle-mounted liquid crystal display device applied to, for example, an instrument panel of a vehicle. As shown in FIGS. 1 to 3, the liquid crystal display device 1 includes a liquid crystal panel 11 disposed on the front side, an edge light type backlight 12 disposed on the back side, the liquid crystal panel 11 and the backlight 12. It has a frame 13 to hold. That is, the liquid crystal panel 11 has a display surface 11A and a back surface 11B on the back side of the display surface 11A, and the backlight 12 irradiates light from the back surface 11B of the liquid crystal panel 11. The liquid crystal display device 1 has a rectangular shape in plan view and is curved along the longitudinal direction.

Although not shown, the liquid crystal panel 11 includes, for example, a liquid crystal layer, two glass substrates (including an alignment film, a transparent electrode, and a color filter) that sandwich the liquid crystal layer, and two sheets disposed outside the glass substrate. Of polarizing plate. By controlling the on / off of the voltage applied to the transparent electrode to change the direction of the liquid crystal molecules, the light passage state is controlled. A display image is formed by the light passing through the polarizing plate.

The liquid crystal panel 11 has a rectangular side defined by a short side (first side) and a long side (second side intersecting the first side) curved in a convex shape on the front side, with the short side being a bus It has a cylindrical surface shape. That is, the four peripheral portions of the liquid crystal panel 11 have two long side portions 11a and two short side portions 11b shorter than each of the long side portions 11a, and a cross section along the longitudinal direction of the liquid crystal panel 11 is The front side has a convex curved shape, and the cross section along the short direction has a linear shape.

The operation of the liquid crystal panel 11 is performed by a control unit (not shown) including a drive circuit and a power supply circuit. The drive circuit and the power supply circuit are disposed, for example, on the rear surface of the rear frame 132 described later.

The backlight 12 is a planar light emitting device that irradiates the liquid crystal panel 11 with light from the back side. The backlight 12 includes a reflector 121, a light guide plate 122 (LGP: Light Guiding Panel), an optical sheet 123, and a light source 124 that emits light toward the end face 122c of the light guide plate 122. Have. The reflection plate 121, the light guide plate 122, and the optical sheet 123 have the same curved shape as the liquid crystal panel 11 and are arranged in parallel with the liquid crystal panel 11.

The light guide plate 122 is a plate-like member made of, for example, polycarbonate or PMMA (Polymethyl methacrylate), diffuses light from the light source 124 incident from the end face, and uniformly emits it to the front side. The reflection plate 121 reflects the light leaked from the light guide plate 122 to the back side toward the front side. The optical sheet 123 includes, for example, a diffusion sheet or a prism sheet, and diffuses light emitted from the light guide plate 122.

The light guide plate 122 has a main surface portion 122a having a curved shape similar to that of the liquid crystal panel 11, and a bent edge portion 122b that is bent and extends from the main surface portion 122a to the back surface side. In other words, the bent edge portion 122 b is bent and extends to the opposite side of the liquid crystal panel 11. The bent edge portion 122b has one end portion along the longitudinal direction, that is, a portion corresponding to one of the long side portions 11a (one of the four peripheral portions) of the liquid crystal panel 11, and the end surface 122c faces the back side. Formed as follows. That is, the bent edge portion 122b is curved along the longitudinal direction.

The bending angle of the bent edge portion 122b is preferably about 90 °, and the coupled portion of the main surface portion 122a and the bent edge portion 122b preferably has an R shape. The length of the bent edge portion 122b is preferably as short as possible. Thereby, the light from the light source 124 can be efficiently guided to the main surface portion 122a. For example, the light guide plate 122 having the above-described shape can be easily formed by using injection molding.

The light source 124 includes a plurality of light emitting elements 124a (for example, white LEDs) and is mounted on a flat belt-like flexible printed board 125. The light source 124 is lit while the liquid crystal display device 1 is on.

The frame 13 has a front frame 131 and a rear frame 132. The front frame 131 is a frame having a shape that matches the outer shape of the liquid crystal panel 11, and holds the liquid crystal panel 11. The rear frame 132 has a shape that matches the curved shape of the liquid crystal panel 11 and supports the backlight 12 from the back side.

The rear frame 132 has a light source accommodating portion 132a that protrudes to the back side at a portion corresponding to the bent edge portion 122b of the light guide plate 122. The light source accommodating portion 132a has a substantially U-shaped cross-sectional shape and is curved along the longitudinal direction. A bent edge portion 122b of the light guide plate 122 is accommodated in the space of the light source accommodating portion 132a, and a flexible printed board 125 on which the light source 124 is mounted is disposed on the bottom surface of the light source accommodating portion 132a. The light source 124 is curvedly disposed along the bent edge 122b of the light guide plate 122 and faces the end surface 122c of the bent edge 122b.

The flexible printed circuit board 125 is arranged in a curved state along the longitudinal direction, that is, in a curved state in the flatwise direction. Therefore, as in Patent Document 2, the positional accuracy of the light source 124 can be easily ensured and the attaching operation to the rear frame 132 is also simpler than the case where the flexible printed circuit board is bent and attached in the edgewise direction.

As described above, the liquid crystal display device 1 according to the first embodiment includes the curved liquid crystal panel 11, the light source 124 and the light guide plate 122, and emits light from the back side of the liquid crystal panel 11. System backlight 12. The light guide plate 122 includes a main surface portion 122a having a curved shape similar to that of the liquid crystal panel 11, and a bent edge portion 122b that is bent and extends from the main surface portion 122a. The light source 124 includes a plurality of light emitting elements 124a disposed to face the end surface 122c of the bent edge 122b.

In the liquid crystal display device 1, the light source 124 faces the end surface 122 c of the light guide plate 122 regardless of the curved shape of the light guide plate 122 or the frame 13. The light from the light source 124 surely enters the light guide plate 122 and is guided to the main surface portion 122a. Therefore, luminance unevenness in the liquid crystal display device 1 is reduced.

In the liquid crystal display device 1, the bent edge 122 b of the light guide plate 122 is formed in a portion corresponding to the long side 11 a among the four peripheral edges of the liquid crystal panel 11, and the light source 124 is along the bent edge 122 b. Is placed. Accordingly, since a large number of light emitting elements 124a can be arranged, the luminance of the display image can be easily ensured. Further, since the LEDs are not concentrated in the vicinity of the drive IC disposed around the short side portion 11b of the liquid crystal panel 11, an increase in the component temperature due to the LEDs can be prevented.

[Second Embodiment]
FIG. 4 is a diagram showing a liquid crystal display device 2 according to the second embodiment of the present invention. FIG. 5 is a cross-sectional view showing the internal structure of the liquid crystal display device 2. FIG. 6 is a diagram illustrating a positional relationship between the light guide plate 222 and the light source 224 in the liquid crystal display device 2. FIG. 5 shows an enlarged cross section of a portion B surrounded by a broken line in FIG.

4 to 6, the liquid crystal display device 2 holds a liquid crystal panel 21 disposed on the front side, an edge light type backlight 22 disposed on the back side, and the liquid crystal panel 21 and the backlight 22. The frame 23 to be used is included. The liquid crystal display device 2 according to the second embodiment is different from the liquid crystal display device 1 according to the first embodiment in that the curved shape is concave on the front side. Since the basic configuration is the same as that of the first embodiment, description thereof is omitted.

The liquid crystal display device 2 includes a liquid crystal panel 21 having a curved shape, an edge light type backlight 22 having a light source 224 and a light guide plate 222 and irradiating light from the back side of the liquid crystal panel 21. The four peripheral parts of the liquid crystal panel 21 have two long side parts 21a and two short side parts 21b shorter than each of the long side parts 21a. The light guide plate 222 includes a main surface portion 222a having a curved shape similar to that of the liquid crystal panel 21, and a bent edge portion 222b that is bent and extends from the main surface portion 222a. The light source 224 includes a plurality of light emitting elements 224a disposed to face the end surface 222c of the bent edge 222b.

The reflecting plate 221, the optical sheet 223, and the flexible printed circuit board 225 correspond to the reflecting plate 121, the optical sheet 123, and the flexible printed circuit board 125 in the first embodiment, respectively. The frame 23 includes a front frame 231 and a rear frame 232, and a light source accommodating portion 232 a is provided in the rear frame 232.

Also in the liquid crystal display device 2, the same effect as the liquid crystal display device 1 of the first embodiment can be obtained. That is, in the liquid crystal display device 2, the light source 224 faces the end surface 222 c of the light guide plate 222 regardless of the curved shape of the light guide plate 222 or the frame 23. The light from the light source 224 surely enters the light guide plate 222 and is guided to the main surface portion 222a. Therefore, luminance unevenness in the liquid crystal display device 2 is reduced.

As described above, the present invention has been specifically described based on the embodiment. However, the present invention is not limited to the above-described embodiment, and can be changed without departing from the gist thereof.

For example, the liquid crystal panel in the present invention may have a curved shape (curved surface shape) other than the cylindrical surface shape shown in the embodiment, and the liquid crystal panel may be curved along the short side portion.

Furthermore, the curvature of the curved shape of the liquid crystal panel is not constant and may vary. Moreover, it is good also as a corrugated curved shape which connected the concave shape and the convex shape. The liquid crystal panel may be curved along both the short side and the long side.

Further, for example, in the case of a cylindrical liquid crystal panel, the bent edge of the light guide plate is formed in a portion corresponding to at least one of the four peripheral edges of the liquid crystal panel, and a light source is disposed on the end surface. That's fine. For example, in the light guide plate, a bent edge portion may be formed at a portion corresponding to the short side portion of the liquid crystal panel that is not curved, and further, a bent edge is provided at a portion corresponding to both the long side portion and the end portion. A part may be formed.

The structure in which the bent edge is provided on the non-curved side of the liquid crystal panel has the following advantages. (1) Compared with a normal edge light system in which LEDs are arranged on the side surface of the light guide plate, the frame can be narrowed. (2) Since the light guide distance to the display area can be increased without enlarging the frame as compared with the normal edge light system, the luminance uniformity of the backlight in the display area can be expected to be improved. (3) Since the LED serving as the heat source is separated from the liquid crystal panel, the temperature rise of the liquid crystal panel due to LED heat generation is suppressed.

Further, the bending angle of the bent edge portion of the light guide plate may not be 90 °. Further, the curvature may be different between the curved shape of the main surface of the light guide plate and the curved shape of the end surface of the bent edge. For example, the curvature of the curved shape of the end surface of the bent edge portion may be smaller than the curvature of the curved shape of the main surface of the light guide plate. By doing so, the flexible printed circuit board in which the light emitting elements are arranged with high density can be easily followed by the curved shape of the end surface of the bent edge. If the end surface of the bent edge is made flat without being bent, the flexible printed circuit board need not be bent.

Further, the bent edge portion of the light guide plate may be formed to be bent toward the front side (display surface side).

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

The liquid crystal display device according to the present invention is suitable for a liquid crystal display device having a curved display surface.

DESCRIPTION OF SYMBOLS 1, 2 Liquid

crystal display device

11, 21

Liquid crystal panel

11a, 21a Long side part

11A Display surface

11b, 21b Short side part 11B Back surface 12, 22 Backlight 121,221 Reflecting plate 122,222

Light guide plate

122a, 222a

Main surface part

122b, 222b Bent edges 122c, 222c

End surfaces

123, 223

Optical sheets

124, 224

Light sources

124a, 224a

Light emitting elements

125, 225 Flexible printed

circuit boards

13, 23

Frames

131, 231

Front frames

132, 232 Rear frames 132a, 232a Light source housing

Claims

A liquid crystal panel having a curved shape and having a display surface and a back surface on the back side of the display surface;
An edge light type backlight having a light source and a light guide plate and irradiating light from the back surface of the liquid crystal panel;
The light guide plate has a main surface portion having a curved shape similar to that of the liquid crystal panel, and a bent edge portion bent and extended from the main surface portion,
The light source has a plurality of light emitting elements disposed to face an end surface of the bent edge portion.
Liquid crystal display device.
The liquid crystal panel has a cylindrical surface shape in which a rectangular plane is curved,
The bent edge is formed in a portion corresponding to at least one of the four peripheral edges of the liquid crystal panel.
The liquid crystal display device according to claim 1.
The four peripheral portions of the liquid crystal panel have two long sides and two short sides shorter than each of the long sides,
The bent edge is provided in a portion corresponding to one of the long sides.
The liquid crystal display device according to claim 2.
The liquid crystal panel is curved along the two long sides.
The liquid crystal display device according to claim 3.
The curved printed circuit board further includes a flexible printed board on which the light source is placed and is arranged along the end surface of the bent edge.
The liquid crystal display device according to claim 1.
The bent edge is bent and extends to the opposite side of the liquid crystal panel;
The liquid crystal display device according to claim 1.