JP2000029009A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bring out character displayed on a liquid crystal panel by imparting perspective to the screen of the liquid crystal display device. SOLUTION: A back light 12 is provided on the reverse surface side of the liquid crystal panel 11. The back light 12 has its light source 17 exposed to the flank of a light guide plate 16, which is divided into a front part layer 16A and a rear part layer 16B superposing on each other through a light diffusion layer 20. Concave light convergence patterns 22A and 22B are formed at the positions of the reverse surface of the front part layer 16A corresponding to the display part 14 of the liquid crystal panel 11. The light convergence patterns 22A and 22B reflect light which is made incident on the front part layer 16A from the light source 17 to the side of the liquid crystal panel 11, so that the part of the display part 14 of the liquid crystal panel 11 illuminates lighter than other parts. The display on the display part 14 of the liquid crystal panel 11 becomes attractive and beautiful and the whole screen gives a feeling of depth because of the distance differences between the display part 14 and light convergence patterns 22A and 22B, so that characters, etc., displayed on the display part 14 are embossed in contrast with the light convergence patterns 22A and 22B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having a screen with a sense of perspective so that display characters and the like appear in a raised state.

[0002]

2. Description of the Related Art In recent years, thin displays and light weight liquid crystal displays (LCD) have been used as displays for audio equipment and portable word processors.
tal-display) is widely used. That L
As is well known, CDs are roughly classified into a segment electrode driving method and a matrix electrode driving method, and the former is classified into a static driving and a dynamic driving, and the latter is a passive matrix (PM) driving and an active driving. It is classified into matrix (AM) drive.
Among them, a TFT-driven AM-LCD using an a-Si type or a p-Si type thin film transistor is excellent in display performance such as contrast and response. However, in any LCD, the liquid crystal itself does not emit light, so that external irradiation light is used. I need.

[0003] Among them, MIN (metal-insu)
There are reflective liquid crystal panels that use natural light as external irradiation light, as seen in AM-LCDs driven by lateral-metal, but those that require brightness and image quality, such as LCDs in vehicles, are transmitted through. Shape is mainstream. For this reason, many LCDs have a backlight on the back side of the liquid crystal panel.

The backlights are roughly classified into three types: a reflector type (direct type), a light guide type (edge light type), and a planar light source type. Among them, the reflector type is one in which a light source such as a fluorescent lamp is housed in an optical housing composed of a reflector and a diffuser, and the light emitted from the light source is reflected and diffused to form a surface light source. . In the light guide method, light emitted from a light source is efficiently made incident from the side of a light guide plate made of acrylic, polycarbonate, or the like, and the incident light is multiple-reflected inside the light guide plate to form a surface light source.
The planar light source system uses a planar light source such as a cold cathode flat plate fluorescent lamp or EL (electroluminescence) as it is.

FIG. 7 is a schematic sectional view of an LCD module equipped with a light guide type backlight. Reference numeral 1 denotes a liquid crystal panel, and 2 denotes a backlight. An LCD module is configured by connecting them with a bezel (not shown). Among them, the backlight 2 is a light source 3 composed of a lamp.
Light guide plate 4 made of transparent material having high light transmittance such as acrylic and acrylic
Are housed in a plastic outer frame 5 to form a unit.
In particular, the light source 3 faces the side surface of the light guide plate 4, and the light guide plate 4 is provided with a reflection layer 6 and a diffusion layer 7 on both sides thereof so as to multiple-reflect the incident light.

FIG. 8 shows an example in which a planar light source 8 composed of an EL, a surface emitting LED, or the like is mounted on the back surface of the liquid crystal panel 1 as a planar light source type backlight. In particular, this LCD is obtained by superimposing two liquid crystal panels 1 and 1. According to this structure, display characters and the like appear to be in a raised state due to a difference between liquid crystal pixels of the front and rear liquid crystal panels 1 and 1. Can be.

[0007]

However, it is costly to stack two liquid crystal panels, and in the case of using a planar luminous body such as an EL as a backlight, the life, cost and durability are disadvantageous. However, there are many problems, and noise is also generated. Therefore, unless high-precision shield processing is performed, the characteristics of electric devices are adversely affected.

In this respect, in the configuration as shown in FIG. 7, there are few problems of noise and cost due to the backlight, but there is no visual effect as when two liquid crystal panels are overlapped, and the display state of characters and the like is poor. It was flat and monotonous.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inexpensive light guide type backlight with less noise so as to obtain a visual effect in which characters and the like displayed on a liquid crystal panel appear in a raised state. I have.

[0010]

According to the present invention, a backlight 1 is provided on the back side of a liquid crystal panel 11 to achieve the above object.
2. A liquid crystal display device comprising:
2 has a light guide plate 16 divided into a front layer 16A facing the back surface of the liquid crystal panel 11 and a rear layer 16B facing the back surface of the front layer, and a light source 17 facing the side surface of the light guide plate 16. A light diffusion layer 20 for diffusing light incident from the light source 17 is interposed between the front layer 16A and the rear layer 16B of the light guide plate, and is incident on the rear surface of the rear layer 16B from the light source 17. A reflection layer 18 for reflecting the reflected light is provided, and the liquid crystal panel 11
The present invention provides a liquid crystal display device having concave light-condensing patterns 22A and 22B for reflecting light incident from the light source 17 toward the liquid crystal panel 11 in correspondence with the predetermined display unit 14 in FIG.

In particular, the invention according to claim 2 provides a liquid crystal display device in which the concave light-condensing patterns 22A and 22B are formed on the back surface of the front layer 16A.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view showing an example of the liquid crystal display device according to the present invention, and FIG. 2 shows a cross section taken along line XX in FIG. In these figures, reference numeral 11 denotes a liquid crystal panel, and reference numeral 12 denotes a backlight provided on the back side thereof, which are mounted as an integral LCD module, for example, in an opening of an operation panel of an audio device (not shown).

Here, the liquid crystal panel 11 is of a transmission type requiring a backlight system, and has, for example, two display sections 13 and 14 on its screen as shown in FIG. Of these, the time is digitally displayed on one of the display units 13 as shown in the figure, and the frequency can be switched to a radio frequency display or the like by operating an operation panel (not shown) in the audio equipment. In addition, the other display unit 14 can display the time in an analog manner, for example, as shown in FIG. The liquid crystal panel 11 has a TN type, IPS type, GH type, ECB type, STN type,
Various types such as shape, PC type, polymer dispersion type, and ferroelectric type can be used (N: nematic liquid crystal, S: smectic liquid crystal).

On the other hand, the backlight 12 comprises a plastic outer frame 15 having a concave cross section, a light guide plate 16 accommodated in the outer frame, and a small light bulb or other light source facing the side of the light guide plate. 17 and the like. Of these, the outer frame 15 is made of a white material having no light transmissivity, and the bottom thereof is formed as a reflective layer 18 that reflects light incident from the side surface of the light guide plate 16 toward the liquid crystal panel 11.
The light guide plate 16 is made of a transparent material having a light transmittance of 80 to 95%, such as acrylic or polycarbonate, and has a notch 19 on one end side of which the light source 17 is arranged. In particular,
The light guide plate 16 is divided into a front layer 16A and a rear layer 16B, which are superposed via the light diffusion layer 20, and the rear layer 16B.
Is placed on the bottom of the outer frame 15 as the reflective layer 18, the liquid crystal panel 11 is provided on the front layer 16 </ b> A side, and the liquid crystal panel is fixed by hooks 21 formed on the outer frame 15.

That is, the backlight 12 is connected to the liquid crystal panel 1.
In order from the first side, the front layer 16 of the light guide plate facing the back surface
A, a light diffusion layer 20, a rear layer 16B of the light guide plate facing the back surface of the front layer via the light diffusion layer, and a reflection layer 18 facing the back surface of the rear layer. The light incident on the light plate 16 is diffused and transmitted by the light diffusion layer 20 while being reflected by the reflection layer 18, so that the entire surface of the liquid crystal panel 11 can be illuminated. The light diffusion layer 20 is formed as a milky white translucent plastic film and is formed separately from the light guide plate 16, and is formed by blasting one of the surfaces between the front layer 16A and the rear layer 16B. , Etc., and can be integrally formed. Further, the reflection layer 18 is also a reflection sheet made of a plastic film or the like different from the outer frame 15 and is attached to the back surface of the rear layer 16B, or is integrally coated with a white pigment on the back surface. It can also be formed.

Here, a high brightness portion is formed on the light guide plate 16 due to the difference in light refractive index. In FIG. 1, 22A, 2
2B is a concave light-condensing pattern as a high-luminance portion, and these light-condensing patterns 22A and 22B are
1 corresponding to the display unit 14 (clock hand in FIG. 1),
It is formed at a portion of the light guide plate 16. Reference numeral 23 denotes a board on which a light source is mounted, and the board 23 is fixed to one end of the outer frame 15. The light source 17 mounted on the substrate 23 has its center at the front layer 16A and the rear layer 16A of the light guide plate.
B faces each side surface of both layers at the boundary with B, and the emitted light is incident on the front layer 16A and the rear layer 16B. Therefore, the light that has entered the light guide plate 16 is multiple-reflected by the reflection layer 18 and the light diffusion layer 20 and irradiates the liquid crystal panel 11 provided in front thereof, thereby displaying characters on the display units 13 and 14 of the liquid crystal panel 11. And figures can be clarified. In particular, the light incident on the light guide plate 16 irradiates a later-described print pattern applied to the portion of the backlight 12, and is reflected at the positions of the condensing patterns 22A and 22B to increase the brightness of the condensing pattern. . As a result, the presence of the print patterns and the light-condensing patterns 22A and 22B is clarified, and a sense of perspective is generated between the liquid crystal panel 11 and the display characters appear on the liquid crystal panel 11 as a three-dimensional screen. Get a visual effect that looks like a state.

FIG. 3 is a partial sectional view of the light guide plate. As is clear from FIG.
2B is formed in a concave shape, for example, on the back surface of the front layer 16A in the light guide plate. These condensing patterns 22A, 22B
Is formed in the thickness direction of the front layer 16A by cutting or the like, and has a depth of 10 to 30%, for example, 0.3 to 1.5 mm with respect to the thickness of the front layer 16A, Light incident on the front layer 16A from the light source 17 can be reflected in the thickness direction thereof and deflected to the liquid crystal panel 11 side. One of the light-condensing patterns 22A is formed by engraving the back surface of the front layer 16A in a circular shape and indicates the boundary of the display unit 14 in the liquid crystal panel 11, and means, for example, the outline of a timepiece as shown in FIG. . The other light-collecting pattern 22B is the light-collecting pattern 2
The rear surface of the front layer 16A is engraved in a dot shape along the inner circumference of 2A, and means, for example, each point of a timepiece as shown in FIG.

Next, FIG. 4 shows a plan view of the front layer. As is clear from this figure, in addition to the condensing patterns 22A and 22B described above, two types of printing patterns 23A and 23B by silk printing or the like are provided on the front layer 16A of the light guide plate.
Is applied. One of the print patterns 23A corresponds to the display section 14 of the liquid crystal panel, and is provided on the front surface of the front layer 16A, that is, on the liquid crystal panel 11 side, inside the condensing pattern 22B. Also, the other print pattern 2
3B is applied to the entire back surface of the front layer 16A in the form of a mesh.

The light converging patterns 22A, 22
According to B and the print patterns 23A and 23B, the screen can be given a perspective and the aesthetic appearance can be improved as described above due to the front-back difference between the display units 13 and 14 in the liquid crystal panel 11. Here, FIG. 5 shows the front layer 16A of the light guide plate in a partially enlarged manner. As shown in this figure, the condensing pattern 22A is a groove having a semicircular cross section, for example, and its concave surface is made rough by etching or blasting. The condensing pattern 22B is, for example, a conical hole, and its concave surface is mirror-finished. Thus, the light incident on the front layer 16A of the light guide plate from the light source 17 is applied to the liquid crystal panel 1 at the positions of the condensing patterns 22A and 22B.
The part is reflected to one side, and the part shines brighter than other parts of the light guide plate 16 to increase the definition. On the other hand, since the print pattern 23B is irradiated from the rear layer 16B side as well as the light incident on the front layer 16A, the print pattern 23B is glossy when viewed from the liquid crystal panel 11 side, and its color tone appears as it is.

The print pattern 23B is connected to the front layer 16A.
Instead of forming on the light diffusion layer 20, the light diffusion layer 20 may be interposed between the front layer 16A and the light diffusion layer 20, for example, by printing on a transparent plastic film. However, the paint used for the processing is preferably a non-black paint such as green or red. Of course, black paint may be used, but characters displayed on the liquid crystal panel 11 are mostly black, and the printed pattern 23B of the same color as the characters is used.
There is a fear that the characters will be difficult to read.

In connection with this, if light from the light source 17 is made incident only on the rear layer 16B, the printed pattern 2
Even if 3B is formed of a green or red paint, it looks dark, so it is desirable to irradiate the print pattern 23B with the light of the light source 17 incident on the front layer 16A from the side as described above.

Further, as the print pattern 23B, it is preferable to use a straight line extending radially as shown in FIG. 4 in order to emphasize the perspective and the three-dimensional effect.
It is possible to further emphasize the visual effect in which the display character 1 appears to be raised in comparison with the print pattern 23B. It should be noted that this can be a curve or a plurality of points, but in any case, if the print pattern 23B is applied to the entire surface of the light guide plate 16, the amount of light reaching the liquid crystal panel 11 is reduced and the function of the backlight is impaired. So the print pattern 23
B is preferably formed on the light guide plate 16 while leaving 80 to 99% of a light permeable area.

FIG. 6 shows a rear layer of the light guide plate. In FIG. 6, (A) shows the front surface of the rear layer 16B,
(B) shows the back surface. First, in FIG. 6A, the front surface of the rear layer 16B, that is, the surface on the front layer 16A side is made matte (rough) by etching or blasting. In FIG. 6B, the back surface of the rear layer 16B, that is, the surface on the side of the reflective layer 18 is also matted by etching or blasting, but has a higher roughness and higher light diffusion than the front surface. According to the rear layer 16B, multiple reflection of light by the reflection layer 18 and the light diffusion layer 20 is promoted, and the back surface of the front layer 16A can be evenly irradiated.

The preferred embodiment of the present invention has been described with reference to the drawings. However, the liquid crystal display device according to the present invention is not limited to a display for audio equipment, but can be used as a portable TV, a word processor, and other displays. .
Further, the light source 17 is not limited to a point light source such as a small light bulb,
For a large screen, a fluorescent lamp can be provided along the side surface of the light guide plate 16.

Further, it is preferable that the light condensing patterns 22A and 22B are formed on the front layer 16A on the liquid crystal panel 11 side with respect to the light diffusion layer 20, as in the above-described example.
Although it is optimal to form it on the back surface apart from the liquid crystal pixel portion, it may be formed on the front surface or on the front and rear surfaces of the rear layer. Further, the condensing pattern can be formed corresponding to the display unit 13 in addition to the display unit 14 of the liquid crystal panel 11.

In particular, the condensing patterns 22A and 22B may be formed not only by processing the portions of the light guide plate 16 such as the front layer 16A into a concave shape, but also by applying a photosensitive agent or a fluorescent paint to the concave surfaces. The concave portions formed as the light collecting patterns 22A and 22B may be filled with another material having a different light refractive index from the light guide plate 16. For example, the light guide plate 16 is made of polystyrene having a refractive index of about 1.59, and the filler is made of acrylic or the like having a lower refractive index.

The light guide plate 16 is preferably divided into a front layer 16A and a rear layer 16B which are superposed via the light diffusion layer 20, but may be a single layer. The front layer 1
6A and the rear layer 16B are further subdivided to form multilayers, as a matter of course.

[0028]

As is apparent from the above description, according to the present invention, since the backlight of the light guide type which does not use a planar light source such as an EL is used, there are few problems of noise and cost, and such a type is not required. The light condensing pattern that reflects the incident light from the light source and shines on the light guide plate at the part of the light guide plate. , The perspective and three-dimensional appearance of the LCD screen occur,
This provides a visual effect that characters and the like displayed on the liquid crystal panel appear to be in a raised state in comparison with the condensing pattern.

Further, the light guide plate is divided into a front layer and a rear layer,
Since the light diffusion layer and the reflection layer are formed facing each other on the front and back sides of the rear layer, the back surface of the front layer can be evenly illuminated, and a concave condensing pattern is formed on the back surface of the front layer Therefore, the glow emitted from the condensing pattern is not diffused by the light diffusion layer and can be clearly confirmed from the liquid crystal panel side.

Further, since the light-condensing pattern is formed corresponding to a predetermined display portion of the liquid crystal panel, the display can be enhanced, and the effect of enhancing visibility and perspective can be obtained. In addition, since the condensing pattern is processed into a concave shape by molding or cutting the back surface of the front layer of the light guide plate, etc., it is possible to reduce the cost, and we have a variety of light guide plates with various condensing patterns Many variations can be provided on the same liquid crystal panel.

[Brief description of the drawings]

FIG. 1 is a plan view showing a liquid crystal display device according to the present invention.

FIG. 2 is a sectional view taken along line XX in FIG.

FIG. 3 is a cross-sectional view showing a light guide plate of a backlight in the device, partially cut away;

FIG. 4 is a plan view showing a front layer of the light guide plate.

FIG. 5 is an enlarged sectional view showing a front layer partially broken away.

FIGS. 6A and 6B are a plan view and a bottom view showing a rear layer of the light guide plate. FIGS.

FIG. 7 is a schematic sectional view showing a conventional liquid crystal display device.

FIG. 8 is a schematic sectional view showing a conventional liquid crystal display device.

[Explanation of symbols]

 Reference Signs List 11 liquid crystal panel 12 backlight 13, 14 display unit 15 outer frame 16 light guide plate 16A front layer 16B rear layer 17 light source 18 reflection layer 20 light diffusion layer 22A, 22B light collecting pattern

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masami Sasaki 3-12-13 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Japan F-term (reference) 2H091 FA14Z FA23Z FA31Z FA41Z FB02 FC14 HA06 LA16

Claims (2)

[Claims] 1. A liquid crystal display device provided with a backlight on the back surface side of a liquid crystal panel, wherein the backlight has a front layer facing the back surface of the liquid crystal panel, and a rear layer facing the back surface of the front layer. A light guide plate, and a light source facing a side surface of the light guide plate, and a light diffusion layer for diffusing light incident from the light source is interposed between a front layer and a rear layer of the light guide plate. A reflection layer for reflecting light incident from the light source is provided on the back side of the rear layer, and light incident from the light source corresponding to a predetermined display unit on the liquid crystal panel is provided on the light guide plate. A liquid crystal display device comprising a concave light-condensing pattern formed on a liquid crystal panel side. 2. The liquid crystal display device according to claim 1, wherein the concave light-condensing pattern is formed on the back surface of the front layer.