JP2006171378A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device which is made so as not to produce emission lines in an effective display region of a liquid crystal display panel. <P>SOLUTION: In the liquid crystal display device which is equipped with the liquid crystal display panel 11, a tubular backlight light source 21, a light guide plate 17 equipped with a storage portion for the tubular backlight light source at the periphery, and a connection portion to driver ICs arranged on the periphery of the liquid crystal display panel, the light guide plate 17 has a canopy 23 for covering the tubular backlight light source on the side of the storing portion 24 for the tubular backlight light source opposite to the liquid crystal display panel 11, wherein a part 23b of the canopy 23 of the light guide plate facing the periphery of the liquid crystal display panel with no connection portion to the driver ICs 12a, 12b arranged thereon is worked into an opaque white color. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device provided with means for preventing bright lines in a light guide plate disposed on the back surface of a liquid crystal display panel in order to prevent generation of bright lines due to a backlight light source appearing on the liquid crystal display panel. About.

As a display device such as a computer, a personal digital assistant, a mobile phone, and a television device, a liquid crystal display device that is low in power consumption, thin, and lightweight has been widely used. Among these display devices, a display device for a car navigation device has recently been required to have a particularly high brightness. As disclosed in Patent Documents 1 and 2, L is used as a backlight light source to increase the brightness. Character-shaped and U-shaped cold cathode tube lamps have been actively used.

A small liquid crystal display device such as a car navigation device is usually close to a liquid crystal display panel, an optical sheet such as a diffusion sheet or a prism sheet, a light guide plate, a reflection sheet, a resin frame surrounding them, and a side end surface of the light guide plate. Backlight light source set, a bottom plate that houses them and covers the back surface, and a front frame that covers the periphery of the front surface of the liquid crystal display panel and the side surface of the assembly, and a gate driver IC and a so-called frame portion of the liquid crystal display panel A driver IC composed of a source driver IC is mounted directly by a COG (Chip On Glass) method or by a TAB method that supports a resin film having a foil electrode, and a control circuit connected to each of these driver ICs is mounted. It is driven by a control circuit board.

That is, the liquid crystal display device 10 such as a car navigation device has a driving IC composed of a gate driver IC 12a and a source driver IC 12b for driving the liquid crystal display panel directly as shown in the exploded perspective view of FIG. Connected to the liquid crystal display panel 11 mounted above and a control circuit board (not shown) mounted with a controller and other electronic components that are connected to each driving IC of the liquid crystal display panel 11 and that control the driving IC. Flexible printed wiring (FPC) substrates 13a and 13b, for example, three optical sheets 15a to 15c arranged on the back surface of the liquid crystal display panel 11, a rectangular flat acrylic resin light guide plate 17, and a light guide plate A white reflector 18 disposed on the back surface and a bottom plate (case) 19 that covers the back surface of the reflector plate are combined, The liquid crystal display panel 11 is supported on the upper side of the resin frame 14 and the other structural members are fitted and stored on the lower side of these constituent members, and the liquid crystal display panel 11 is fitted to the bottom plate 19. The front frame 22 is fitted and assembled from the front.

A flange 23 is provided around the light guide plate 17 along the side end surface thereof, and a tubular backlight light source 21 is formed in a gap between the flange 23 of the light guide plate 17, the resin frame 14, and the reflection plate 18. The tubular backlight light source housing 24 is disposed and attached. The tubular backlight light source 21 is arranged so that the emission surface of the tubular backlight light source 21 is parallel to a side edge (side end surface) which is a light incident surface of a light guide plate 17 made of transparent acrylic resin or the like. Also, FP
C13a and 13b are guided to the back surface by turning the side surface of the resin frame 14, and are attached to a control circuit board (not shown) provided on the back surface of the reflection plate 18.

In the liquid crystal display device 10 having such a configuration, the tubular backlight light source 21 is positioned outside the effective display region De of the liquid crystal display panel 11 so that the effective light emitting region R of the corresponding light guide plate is positioned.
e is provided outside. However, in the liquid crystal display device 10 such as a car navigation device, there is a demand for narrowing the frame to narrow the front frame 22 and increase the effective display area De of the liquid crystal display panel 11, and as shown in FIG. On the unconnected side of the display panel 11, that is, on the sides 11c and 11d where the driving IC composed of the gate driver IC 12a and the source driver IC 12b of the liquid crystal display panel 11 does not exist, there is almost a margin between the effective display area De and the periphery. It is arranged in a truncated form. 2 is a plan view of the conventional liquid crystal display device of FIG. 1 with the entire frame 22 removed.

For this reason, the light guide plate 17 of the backlight device is similarly arranged. For example, as shown in FIG. 7 which is a cross-sectional view taken along the line AA of FIG. 2, the connection side of the liquid crystal display panel 11, that is, the liquid crystal display panel. On the sides 11a and 11b on which the drive ICs 12a and 12b exist, there is a distance between the effective display area De of the liquid crystal display panel 11 and the tubular backlight light source 21, but the drive IC of the liquid crystal display panel 11 On the non-existing sides 11c and 11d, as shown in FIG. 8 which is a BB cross-sectional view of FIG. 2, there is almost a margin between the effective display area De of the liquid crystal display panel 11 and the tubular backlight light source 21. There is no. Therefore, for example, when a U-shaped lamp is used to increase the brightness of the screen, light from the tubular backlight light source 21 leaks and bright along the periphery when the side 11d where no driving IC is present is viewed from the viewer side. There was a problem of being observed as a streak-like bright line.

In light of the light guide plate 17, the light from the tubular backlight light source tends to gather at the corner portion 23 a where the collar 23 forming the tubular backlight light source housing 24 is connected to the light guide plate. It is easy to see the bright lines on the sides 11c and 11d where there is no driving IC having a sufficient margin to the effective display area De of the liquid crystal display panel 11. On the other hand, on the sides 11a and 11b where the driving ICs are present, the effective display area De of the liquid crystal display panel 11 is displayed.
Such a problem is unlikely to occur because there is inevitably a distance between the light source and the tubular backlight light source 21.

Therefore, in order to prevent the bright lines as described above from being visible, metal such as gold, silver, and aluminum is deposited on the outer periphery of the light source to prevent light leakage as in the invention disclosed in Patent Document 1 below. A flexible reflective film such as a vinyl chloride sheet is attached to the end of the light guide plate,
It may be possible to cover the side of the light guide plate and the back of the light source lamp, but such a pasting process is cumbersome because it is a manual operation, and it increases the number of steps and costs. However, there is a problem in that the unevenness of pasting is large and the bright line is visible or invisible, so that the reliability is not sufficient. In addition, as in the invention disclosed in Patent Document 2 below, when the light incident surface directly above the lamp is surrounded by a low-transmittance reflecting plate, the reflecting plate can be applied only up to the lamp housing chamber, If the reflector is further spread out, the loss of light incident on the light guide plate increases, so it is not possible to cover the area where the brightest line is most likely to occur, so it is not possible to prevent the bright line. There is a problem that causes
JP-A-5-232468 (FIG. 1, [0018]) JP 2000-294024 A ([0030] to [0032])

As described above, in the conventional liquid crystal display device 10, the sides 11c and 1c of the liquid crystal display panel 11 on which the drive ICs 12a and 12b, in particular where bright lines may be observed, are not disposed.
There is a need for measures to prevent bright lines in 1d. In addition, the countermeasures must be inexpensive and reliable.

As a result of various studies to solve the above problems, the inventor of the present application has focused on the flange portion around the light guide plate covering the backlight light source, and improved the light guide plate so that the bright line cannot be directly seen from this portion. Thus, the present inventors have found that the problem can be solved and have completed the present invention.

That is, an object of the present invention is to provide a liquid crystal display device capable of eliminating the generation of bright lines in the effective display area of the liquid crystal display panel, and thus to provide a liquid crystal display device with improved display quality while narrowing the frame. There is.

The object of the present invention can be achieved by the following constitution. That is, the invention of the liquid crystal display device according to claim 1 of the present application includes a liquid crystal display panel, a light guide plate disposed below the liquid crystal display panel, and a backlight light source disposed around the light guide plate. In the liquid crystal display device, the periphery of the liquid crystal display panel has a connection side provided with a connection part to the driving IC and an unconnected side provided with no connection part. A ridge that covers the backlight source is formed between the backlight light source and the liquid crystal display panel, and the ridge of the light guide plate is processed to be opaque on the unconnected side of the liquid crystal display panel. It is characterized by.

The invention according to claim 2 of the present application is characterized in that, in the liquid crystal display device according to claim 1, the ridges of the light guide plate are processed to be transparent at the connection side of the liquid crystal display panel.

The invention according to claim 3 of the present application includes a liquid crystal display panel, a light guide plate disposed below the liquid crystal display panel, a backlight light source disposed around the light guide plate,
In the liquid crystal display device comprising: the periphery of the liquid crystal display panel has a connection side provided with a connection portion to the driving IC and an unconnected side provided with no connection portion, the light guide plate A transparent collar portion and an opaque collar portion covering the backlight light source are formed between the backlight light source and the liquid crystal display panel, and the transparent collar is formed at the connection side of the liquid crystal display panel. It is characterized in that the part is located.

The invention according to claim 4 of the present application includes a liquid crystal display panel, a light guide plate disposed below the liquid crystal display panel, a backlight light source disposed around the light guide plate,
In the liquid crystal display device comprising the liquid crystal display panel, the periphery of the liquid crystal display panel includes a connection side provided with a connection portion to the driving IC and an unconnected side provided with no connection portion. In the unconnected side, an opaque collar portion that covers the backlight light source is formed on the light guide plate between the backlight light source and the liquid crystal display panel.

The invention according to claim 5 of the present application is the liquid crystal display device according to any one of claims 1 to 4, wherein the light guide plate is formed by two-color molding.

The invention according to claim 6 of the present application is the liquid crystal display device according to any one of claims 1 to 5, wherein the driving IC is disposed directly at a connection portion to the driving IC and has a foil-like electrode. It is supported by a resin film or disposed on a control circuit board separate from the liquid crystal display panel.

The invention according to claim 7 of the present application is the liquid crystal display device according to any one of claims 1 to 6, wherein the backlight light source is an L-shaped or U-shaped tubular light source. .

The present invention provides the following excellent effects by having the above configuration. That is, according to the invention according to claim 1, claim 3, and claim 4 of the present application, when the liquid crystal display panel is viewed from the observer side, the bright line due to the backlight source becomes invisible in the effective display area, As in the conventional example, there is no need to attach a reflector to the light guide plate or to install a lamp house.
A liquid crystal display device that can efficiently perform the assembly work of the backlight source, can easily expand the effective display area of the liquid crystal display panel, and narrow the frame portion, and is useful as a display device such as a car navigation device. Can be provided.

Further, according to the invention according to claim 2 of the present application, it is possible to prevent the bright line from the backlight light source from being visible even if the light guide plate located on the connection side is transparent or milky white. If this portion is kept transparent, the light utilization efficiency can be increased.

Further, according to the invention according to claim 5 of the present application, the milky white portion can be easily and quickly formed by two-color molding, and a light guide plate having a uniform quality can be obtained. A display device is obtained.

According to the invention of claim 6 of the present application, the gate driver IC and the source driver I
C is a so-called COG method that is directly arranged on the frame portion of the liquid crystal display panel, a so-called TAB method that is supported by a resin film having a foil-like electrode, or is arranged on a drive circuit substrate separate from the liquid crystal display panel. It can also be applied to a system, and an appropriate system can be adopted according to the size of the liquid crystal display device.

Further, according to the invention of claim 7 of the present application, the amount of light incident on the light guide plate per backlight light source increases, so that a liquid crystal display device with low power consumption and high luminance can be obtained.

Hereinafter, an embodiment of the liquid crystal display device according to the present invention will be described in detail with reference to the accompanying drawings. The basic configuration of the liquid crystal display device of this embodiment is the conventional example shown in FIGS. The liquid crystal display device 10 is substantially the same as the liquid crystal display device 10 shown in FIG. 1, and FIG. 1 and FIG. 2 are referred to. However, the embodiments shown below exemplify a liquid crystal display device adopting a COG method as a fixing method of a driving IC composed of a gate driver IC and a source driver IC in order to embody the technical idea of the present invention. However, the present invention is not intended to be specified in this embodiment, and the present invention can be equally applied to various modifications without departing from the technical idea shown in the claims. It is.

3 is a partially transparent front view of the backlight used in the liquid crystal display device according to the embodiment, FIG. 4 is a transparent view of the backlight of FIG. 3, and FIG. 5 is a bottom plate portion of the backlight of FIG. FIG. 6 is a rear view from the rear side with the bottom of the reflector removed, and FIG. 6 is an enlarged cross-sectional view corresponding to line AA in FIG. 2.

FIG. 3 shows the arrangement of the light guide plate 17 disposed below the liquid crystal display panel 11 and the see-through tubular backlight light source 21 in the backlight used in the example. In this embodiment, a tubular backlight light source 21 such as a U-shaped cold cathode tube is disposed around the light guide plate 17, and a backlight is configured with the reflector 18 and the bottom plate 19.

The light guide plate 17 is made of acrylic resin, polycarbonate, polyethylene terephthalate (PE
T) is a substantially rectangular parallelepiped plate made of a transparent resin plate or a transparent glass plate having a high light transmittance and having an effective light emitting area Re slightly larger than the effective display area De of the liquid crystal display panel. It has a bowl-shaped part, and this bowl-shaped part forms a storage part for a tubular backlight light source. An L-shaped tubular backlight light source extending over two sides or a U-shaped tubular backlight light source extending over three sides is arranged on the side end surface, and the other two sides or one side is connected to these tubular backlight light sources. The cable to be wired is wired.

The front surface of the light guide plate 17 is a light emitting surface, and a diffusion sheet made of translucent polycarbonate or the like having a high light transmittance is provided to uniformly diffuse light from the tubular backlight light source. Further, the back surface of the light guide plate 17 is subjected to dot-like processing, scratches, or embossing by screen printing so as to diffusely reflect light. Furthermore, on the back side of the light guide plate, a reflector made of white polyester or a polyester film with a silver deposited film is arranged,
The diffusion sheet, the light guide plate, the reflection plate, and the tubular backlight light source constitute a backlight.

In the present embodiment, among the ridges of the light guide plate 17, the ridges 23b of the tubular backlight light source storage portion 24 provided around the two sides 17c and 17d are made opaque, specifically milky white, and are U-shaped. One side of the tubular backlight light source 21 cannot be seen from the surface. On the other hand, on the side of the periphery 17c, 17d, the collar 23c of the tubular backlight light source storage part 24 is formed transparent so that the portion of the tubular backlight light source 21 can be seen through from the front. The inner portion from the inner dotted line 17e is the effective light emitting region Re of the light guide plate 17 facing the effective display region of the liquid crystal display panel. Further, a connector 26 for external connection is connected to the tubular backlight light source 21 via a cable 25. 4 is a perspective view from the front showing the arrangement of the light guide plate 17, the tubular backlight light source 21, and the connector 26, including portions that were not visible in FIG. 3. Further, both ends of the tubular backlight light source 21 and important points along the way are held by a lamp holder 27. FIG. 5 is a rear view of the bottom plate portion and the bottom of the reflection plate, viewed from the back side.

In the liquid crystal display panel 11 used in this embodiment, the driving IC composed of the gate driver IC 12a and the source driver IC 12b is respectively a liquid crystal display panel 11 by the COG method.
Are mounted on different sides of one of the boards. When this liquid crystal display panel 11 is placed on the surface of the backlight used in the present embodiment, the conventional liquid crystal display device 1 shown in FIG.
The configuration is the same as in the case of 0. In this case, the light guide plate 17 is connected to the liquid crystal display panel 11,
That is, the sides 11a and 11b of the liquid crystal display panel 11 where the driving ICs 12a and 12b exist.
Then, for example, as shown in FIG. 7, there is a sufficient distance between the effective display area De of the liquid crystal display panel 11 and the tubular backlight light source 21. On the other hand, on the unconnected side of the liquid crystal display panel, that is, the sides 11c and 11d where the driving ICs 12a and 12b of the liquid crystal display panel 11 do not exist, as shown in FIG. Light source 2
It is close to 1 and there is almost no distance between them. Therefore, the liquid crystal display panel 1
When the sides 11c and 11d on which the driving ICs 12a and 12b do not exist are viewed from the observer side, light from the tubular backlight light source 21 leaks and is observed as bright streak-like bright lines along the periphery.

Therefore, in the present embodiment, as shown in FIG. 6 which is an enlarged cross-sectional view corresponding to the line AA in FIG. 2, at least among the ridges 23 forming the tubular backlight light source storage portion 24 of the light guide plate 17. On the sides 11c and 11d where the driving ICs 12a and 12b are not arranged and the effective display area De of the liquid crystal display panel 11 is approaching the periphery, it is formed as a milky white ridge 23b.

As described above, when the light guide plate 17 is structurally viewed, the light from the tubular backlight light source 21 is likely to gather at the corner portion 23a where the collar 23 forming the backlight light source storage portion 24 is connected to the light guide plate. It tends to be the brightest line. Therefore, at least this portion of the light guide plate 17
Is preferably milky white. In this embodiment, the ridges 23 are 17c and 17d milky white ridges 23b and the other portions 17a and 17b are transparent ridges 23c. However, driver I
The entire ridge of the tubular backlight light source storage unit 24 including the C arrangement side may be processed into milky white.

The collar 23 of the tubular backlight light source housing 24 of the light guide plate 17 of the present invention preferably has a transparent part and a milky white part produced by two-color molding. Since the milky white part can be easily and quickly formed by forming the milky white part by two-color molding, the light guide plate can be formed uniformly and accurately, so that a highly reliable one can be obtained. In this two-color molding, a part of the tubular backlight light source housing 24 in the thickness direction of the ridge 23 is formed into a milky white ridge 23a, but the whole is processed into a milky white ridge 23a in the thickness direction. There is no problem.

Here, the two-color molding refers to a molding method for producing an integrated product made of two colors or two kinds of resins, as is well known. Normally, a special machine equipped with two sets of injection devices is used for molding. First, mold the first color (first material) from the first cylinder, open the mold once, close the mold by rotating the mold turntable 180 degrees with the primary molded product attached to the core side, It can be manufactured by molding the second color (second material), then opening the mold, and taking out the molded product from the mold. The two-color molding is effective in forming the milky white portion with respect to the transparent portion of the light guide plate because the transparent portion and the milky white portion can be formed accurately and uniformly.

In addition, although the light guide plate 17 molded in two colors in the embodiment has a transparent portion and a milky white portion,
The milky white portion is not necessarily limited to milky white as long as it is opaque. In order to prevent bright lines, light gray or the like may be used as long as light can be absorbed and reflected. However, milky white is preferable because light can be appropriately shielded and the light reuse efficiency is better than gray.

If the tubular backlight light source 21 is L-shaped or U-shaped, the amount of light incident on the light guide plate per lamp increases, and the liquid crystal display device 10 can obtain high luminance with low power consumption. Even if these lamps are used, according to the above-described configuration, the bright line is not generated, and the liquid crystal display device 10 having a compact and large display area can be obtained.

In particular, in a 6-inch to 8-inch class liquid crystal display device for in-car use or portable DVD player, for example, the size of the display device itself is approximately the size of the device on which the display device is mounted, and the display area is While securing the conventional size, the frame portion is narrowed to reduce the size of the device itself on which the display device is mounted. Therefore, the present invention is extremely effective in a liquid crystal display device for in-vehicle use of 6 to 8 inches class whose frame portion is extremely narrow.

As described above, as the liquid crystal display device, the liquid crystal display panel 11 has a driving IC composed of the gate driver IC 12a and the source driver IC 12b by the COG method.
However, the present invention can be applied even when driver ICs are concentrated on one side. Further, these driving ICs are not only those mounted by the COG method but also those of the so-called TAB method supported by a resin film having foil-like electrodes, or separated from the liquid crystal display panel. It may be of a type attached to a control circuit board (not shown).

Furthermore, the milky white ridges 23b may be provided not only on the periphery of the light guide plate facing the periphery where the driving ICs of the liquid crystal display panel are not mounted, but also on all sides.

Regardless of the above-described embodiments, the shape of the eaves 23a of the milky white portion can be appropriately designed according to the shape and arrangement of the tubular backlight light source of the light guide plate.

Further, in the examples, only a tubular backlight light source made of a cold cathode tube is described, but the backlight light source is not limited to a tubular light source, for example, a point light source such as an LED or a point light source. The light source may be arranged in the same direction to form a linear light source. The present invention is effective for a case where a bright line is observed in the display area because the light source is arranged and the distance between the display area and the light source is short.

Even if the backlight light source is arranged only on one side, if the backlight light source is arranged on the unconnected side of the liquid crystal display panel, it is possible to prevent bright lines by forming an opaque wrinkle there. It is possible and effective.

It is a disassembled perspective view of the liquid crystal display device of a prior art example. It is the top view which removed the front frame of the liquid crystal display device which concerns on a prior art example. It is a partially transparent front view of the backlight used for the liquid crystal display device which concerns on an Example. FIG. 4 is a perspective view of the backlight of FIG. 3. FIG. 4 is a rear view of the backlight of FIG. 3 as viewed from the back side with the bottom plate portion and the bottom of the reflector plate removed. It is an expanded sectional view corresponding to the AA line of FIG. 2 in the liquid crystal display device of an Example. It is an AA line expanded sectional view of FIG. FIG. 3 is an enlarged sectional view taken along line B-B in FIG. 2.

Explanation of symbols

10 Liquid Crystal Display Device 11 Liquid Crystal Display Panel 12a Gate Driver IC
12b Source driver IC
13a, 13b Printed circuit board 14 Resin frames 15a-15c Optical sheet 17 Light guide plate 18 Reflector plate 19 Bottom plate 21 Tubular backlight light source 22 Front frame 23 庇 23a Transparent ridge 23b Milky white casket 24 Tubular backlight light source storage

Claims (7)

A liquid crystal display panel;
A light guide plate disposed below the liquid crystal display panel;
A backlight source disposed around the light guide plate;
In a liquid crystal display device comprising:
In the periphery of the liquid crystal display panel, there are a connection side provided with a connection part to the driving IC and an unconnected side provided with no connection part,
In the light guide plate, a ridge that covers the backlight light source is formed between the backlight light source and the liquid crystal display panel,
The liquid crystal display device according to claim 1, wherein a ridge of the light guide plate is processed to be opaque at an unconnected side of the liquid crystal display panel. The liquid crystal display device according to claim 1, wherein a flange of the light guide plate is processed to be transparent at a connection side of the liquid crystal display panel. A liquid crystal display panel;
A light guide plate disposed below the liquid crystal display panel;
A backlight source disposed around the light guide plate;
In a liquid crystal display device comprising:
In the periphery of the liquid crystal display panel, there are a connection side provided with a connection part to the driving IC and an unconnected side provided with no connection part,
The light guide plate is formed with a transparent collar part and an opaque collar part covering the backlight light source between the backlight light source and the liquid crystal display panel,
The liquid crystal display device, wherein the transparent flange portion is located at a connection side of the liquid crystal display panel. A liquid crystal display panel;
A light guide plate disposed below the liquid crystal display panel;
A backlight source disposed around the light guide plate;
In a liquid crystal display device comprising:
In the periphery of the liquid crystal display panel, there are a connection side provided with a connection part to the driving IC and an unconnected side provided with no connection part,
In the non-connected side of the liquid crystal display panel, an opaque collar portion that covers the backlight light source is formed on the light guide plate between the backlight light source and the liquid crystal display panel. . 5. The liquid crystal display device according to claim 1, wherein the light guide plate is formed by a two-color molding process. The driving IC is arranged directly at a connection portion to the driving IC, supported by a resin film having a foil-like electrode, or arranged on a control circuit board separate from the liquid crystal display panel. The liquid crystal display device according to claim 1. The liquid crystal display device according to claim 1, wherein the backlight light source is an L-shaped or U-shaped tubular light source.

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