JPH11174443A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a bright display screen and also to reduce total power consumption by improving the efficiency of light in a LCD. SOLUTION: A condenser lens 30 is pivoted by a rotary shaft 301 in a case 40 so as to be vertically turnable. Lighting efficiency can be improved optimally setting an angle of the condenser lens 30 according to an external light position. Since more light is caught by a reflecting plate 31 and diffusing plate 21 by tilting the main traveling direction of the light guided into a light guide plate 11, a utilization efficiency of light can be improved.

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 (LCD) for performing display utilizing the electro-optical anisotropy of liquid crystal.
More particularly, the present invention relates to a liquid crystal display device in which power consumption of a backlight is reduced.

[0002]

2. Description of the Related Art An LCD is constructed by sealing liquid crystal between electrode substrates having transparent electrodes formed on a transparent substrate. Since the liquid crystal has electro-optical anisotropy, by applying a desired voltage between the electrodes to form an electric field in the liquid crystal, the liquid crystal exhibits optical characteristics according to the electric field intensity. By utilizing this property and applying a different voltage to each pixel, a display image is created as an aggregate of pixels exhibiting a desired luminance. As described above, the LCD has a display image created by voltage control, has advantages such as small size, thin shape, and low power consumption, and has been put to practical use in fields such as OA equipment and AV equipment. In particular, when used for forms,
It is often used outdoors, and a device has been developed in which the total power consumption is greatly reduced by visualizing the display screen using abundant external light.

FIG. 5 shows a configuration diagram of such an LCD.
(10) is an LCD panel, (20) is a light source, (15) is a light guide plate, (35) is a reflection plate, (25) is a diffusion plate, and (3)
Reference numeral 0) denotes a condenser lens, and reference numeral 40 denotes a housing for holding these units. The light source (20) is made of a fluorescent lamp with a reflector (201) arranged behind, and the light guide plate (15) is made of an acrylic resin or the like. The diffusing plate (25) and the reflecting plate (35) may be formed by integrally subjecting the front surface and the back surface of the light guide plate (15) to diffusion processing and irregular reflection processing. The light source (20), the light guide plate (15), the reflection plate (25), and the diffusion plate (35) constitute a backlight which is an illumination unit. As the condenser lens (30), a lens separate from the light guide plate (15), or a lens processed integrally with the light guide plate (15) is used. A window (41) for lighting is opened in the housing (40), and the condenser lens (3) is opened.
0) peeks outside.

The light emitted from the light source (20) or the light taken in from the condenser lens (30) is transmitted to the light guide plate (15) and diffused by the diffuser plate (25) and reflected. The light is irregularly reflected by the plate (35). Then, the LCD panel (1) is converted into uniform plane light by the diffusion plate (25).
0). The LCD panel (10) cannot emit light by itself, and by illuminating from behind as described above, a recognizable preceding display screen is visualized as a distribution of transmitted light.

In this configuration, in an environment where the outside light is abundant, such as a sunny outdoors, the light source (20) is turned off and the light is illuminated only by the light from the condenser lens (30), and the outside light such as indoors In a state where is insufficient, it is possible to use the light source (20) to obtain a bright display screen by turning on the light source (20).
Total power consumption is reduced.

[0006]

In the LCD shown in FIG. 7, the focal point of the condenser lens (30) and the focal point of the light source (20) are located on a plane parallel to the plane of the LCD panel (10). I have. For this reason, much of the light emitted from the light source (20) travels in parallel inside the light guide plate (15) and leaks outside from the condensing lens (30) located on the opposite side. The light taken in from the condenser lens (30) is also
The light travels in parallel inside the light guide plate (15), is reflected by the reflector of the light source (20), travels in the light guide plate (15) in the opposite direction, and leaks again from the condenser lens (30) to the outside. That is,
LC captured by diffuser (25) and reflector (35)
The amount of light emitted toward the D panel (10) decreases,
Light use efficiency was poor.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and has been made in view of the above circumstances, and has an object to provide a liquid crystal display panel having a liquid crystal sealed between a pair of transparent electrode substrates having predetermined electrodes formed on opposing surfaces. A light guide section corresponding to the display section of the liquid crystal display panel and provided with a reflective layer on the back side opposite to the front face facing the liquid crystal display panel, connecting the light guide section to an optical path to take in external light A liquid crystal display device comprising a light condensing unit and / or a light source unit that emits light, and an illuminating unit that irradiates the liquid crystal display panel with light, wherein the light converging unit and / or the light source unit emits the main light. The direction is rotatably controlled, and the main traveling direction of the light introduced into the light guide section is
The light guide section is configured to be non-parallel and non-perpendicular to the main plane.

As a result, most of the light taken in from the light condensing part and / or the light emitted from the light source travels toward the front or back of the light guide part, and is caught by the front or reflective layer to be applied to the liquid crystal display device. Irradiates light to improve the light use efficiency. In particular, the condensing part is a partial columnar shape having a rectangular side plane, and this side plane is disposed so as to face a side surface of the light guide plate, and the side plane of the light condensing part is a side surface of the light guide plate. Is configured to be controlled.

Thus, the light taken in from the light condensing part is refracted by the side plane of the light guiding part, and the main traveling direction of the light introduced into the light guiding part is oblique to the main plane of the light guiding part. And directed to the front of the light guide or to the reflective layer.

[0010]

FIG. 1 is a side sectional view of an LCD according to a first embodiment of the present invention. (10) is LCD
Panel, (11) is a light guide plate, (21) is a diffusion plate, (3)
1) is a reflection plate, (20) is a light source, (30) is a condenser lens, and (40) is a housing for holding these units. The light source (20) is made of a fluorescent lamp with a reflector (201) disposed behind, and the light guide plate (11) is made of an acrylic resin or the like. The diffusing plate (21) and the reflecting plate (31) may be formed by integrally subjecting the front surface and the back surface of the light guide plate (11) to diffusion processing and irregular reflection processing. These light sources (2
0), the light guide plate (11), the reflection plate (21), and the diffusion plate (3).
1) constitutes a backlight. Condensing lens (3
No. 0) is a lens separate from the light guide plate (11) or the same acrylic resin as the light guide plate (11) processed into a partial columnar shape having one side surface of a rectangle. Further, a window (41) for lighting is opened in the housing (40) so that the condenser lens (30) can be seen outside.

Further, as the LCD panel (10), by using a thin film transistor using a polycrystalline semiconductor such as polysilicon, a display pixel portion and a peripheral drive circuit are integrally formed on the same substrate. It is desirable to use a built-in driver type. This eliminates the need for an external driver IC, so that the frame around the display screen is reduced, and further miniaturization and weight reduction are achieved, so that an optimal LCD for portable use is obtained.

In the present invention, the condenser lens (30) has a semicircular or partial circular cross section as shown in the figure, and is elongated in a direction perpendicular to the paper surface along one side of the light guide plate (11). The lens is a partial columnar lens, the curved surface portion of which is a light-receiving surface, the side flat surface portion is a light extraction surface, and faces the side surface of the light guide plate (11). And this condenser lens (30)
Has a rotating shaft (301) supported on the other side, on the front side, or on both sides, and is rotatably fixed. The condenser lens (30) is supported, for example, by an arm attached to the housing (40). Light guide plate (1
As shown in FIG. 1A, a space is provided between 1) and the condenser lens (30) so that the condenser lens (30) can be rotated. Also, a condenser lens (30)
Can be manually controlled.

With this configuration, for example, as shown in FIG. 1B, the condenser lens (30) is rotated downward. With the light exit surface of the condenser lens (30) at the upper end in contact with the side surface of the light guide plate (11), the rotation angle is maximized. An air layer whose thickness changes according to the inclination of the condenser lens (30) is interposed between the condenser lens (30) and the light guide plate (11).

In this state, external light taken in by the condenser lens (30) is perpendicularly extracted from the light exit surface of the inclined condenser lens (30), and obliquely enters the side surface of the light guide plate (11). Incident. The main traveling direction of the light introduced into the light guide plate (11) in this manner is inclined toward the rear surface of the light guide plate (11), and the light is reflected on the reflection plate (11) provided on the rear surface of the light guide plate (11). 31) is obliquely incident. Therefore, most of the introduced light is captured by the reflector (31) and is irregularly reflected. The diffusely reflected light is diffused toward the diffusion plate (21) provided on the front surface of the light guide plate (11). Part of the diffused light is radiated to the LCD panel (10) as uniformed parallel light. The rest again goes to the reflector (31) and is similarly irregularly reflected. The light thus introduced into the light guide plate (11) travels in the left-right direction while reciprocating up and down,
The light source (20) is reached with a gradual decrease. Light source (2
The light reaching 0) is reflected by the reflector (201),
The light is returned to the light guide plate (11) again, and a part thereof is finally leaked out by the condenser lens (30).

Further, as shown in FIG. 1C, the condenser lens (30) is rotated upward. The light exit surface of the condenser lens (30) is in contact with the side surface of the light guide plate (11) at the lower end,
The rotation angle is maximized. With this configuration, the condenser lens (3
The external light taken in from 0) is obliquely incident on the side surface of the light guide plate (11), and the main traveling direction of the light inside the light guide plate (11) is inclined toward the front surface of the light guide plate (11) and is guided. The light is obliquely incident on the diffusion plate (21) provided on the front surface of the light plate (11). For this reason, most of the light introduced into the light guide plate (11) is caught and diffused by the diffusion plate (21), and a part of the light is made uniform and irradiated on the LCD panel (10). The light guide plate (1) is directed toward the reflection plate (31).
1) It travels inside and is irregularly reflected. This reflected light is similarly diffused again toward the diffusion plate (21). Thus,
The introduced light reciprocates up and down in the light guide plate (11) between the diffusion plate (21) and the reflection plate (31), and is partially irradiated on the LCD panel (10) and reduced. Proceed right and left. Then, the light that has reached the light source (20) is reflected by the reflector (201), is returned to the light guide plate (12) again, and the light that has reached the condenser lens (30) leaks out.

Here, the acrylic resin, which is the material of the light guide plate (11), has a higher refractive index than air, and light derived from the condenser lens (30) is obliquely incident on the side surface of the light guide plate (11). When the light is refracted, the outgoing angle is smaller than the incident angle. Therefore, inside the light guide plate (11),
The main traveling direction of the light is inclined at an angle slightly lower than the angle at which the condenser lens (30) is rotated.

In the present invention, as described above, the light guide plate (1)
The main traveling direction of the light introduced into 1) can be non-parallel to the main plane of the light guide plate (11), and is directed to the reflection plate (31) or the diffusion plate (21). For this reason,
The amount of light captured by the reflection plate (31) and the diffusion plate (21) is large, and the amount of light applied to the LCD panel (10) is increased. Accordingly, the amount of light that reciprocates right and left in the light guide plate (11) and finally leaks from the condenser lens (30) is reduced. Therefore, the display efficiency is high and the display screen is sufficiently bright even with a relatively small amount of collected light.
In addition, power consumption can be reduced by reducing the frequency of use of the light source (20) or decreasing the light emission luminance. Furthermore, by setting the angle of the condenser lens (30) optimally according to the position of sunlight outdoors or illumination indoors, the lighting efficiency can be further improved.

FIG. 2 is a side sectional view of an LCD according to a second embodiment of the present invention. In the present embodiment, the light source (20) is a fluorescent lamp that extends along one side surface of the light guide plate (11) in a direction perpendicular to the plane of the drawing, and a reflector having a semicircular or partial circular cross-sectional shape behind the fluorescent lamp. (202), and the emission surface of the light source (20) faces the side surface of the light guide plate (11). The light source (20) is provided on the rotating shaft (20) on the other side or the front side or on both sides.
2) is supported, and is rotatably fixed.
The light source (20) is supported by, for example, an arm attached to the housing (40). As shown in FIG. 2A, a space is provided between the light guide plate (11) and the light source (20) so that the light source (20) can be rotated. Further, the rotation angle of the light source (20) can be manually controlled.

In this configuration, for example, as shown in FIG. 2B, the light source (20) is directed downward. With the reflector (201) of the light source (20) in contact with the side surface of the light guide plate (11) at the upper end, the rotation angle is maximized. An air layer whose thickness changes according to the inclination of the light source (20) is interposed between the light source (20) and the light guide plate (11). In this state, the light emitted from the light source (20) goes obliquely downward and is obliquely incident on the side surface of the light guide plate (11).
The light introduced into the light guide plate (11) is in a state where its main traveling direction is directed to the back side of the light guide plate (11). Therefore, most of the introduced light is captured by the reflecting plate (31) provided on the back surface of the light guide plate (11) and is irregularly reflected.
The light that has been diffusely reflected further decreases and reciprocates in the light guide plate (11) up and down in the light guide plate (11) between the diffusion plate (21) and the reflection plate (31), as in the first embodiment. I do. Part of the light leaks from the condenser lens (30).

Further, as shown in FIG.
Rotate 0) upward. Reflector (2) of light source (20)
01) is a state in which the lower end is in contact with the side surface of the light guide plate (11),
The rotation angle is maximized. In this configuration, the external light taken in from the light source (20) is obliquely incident on the side surface of the light guide plate (11), and the main traveling direction of the light inside the light guide plate (11) is the same as that of the light guide plate (11). The light guide plate (1
The light is obliquely incident on the diffusion plate (21) provided on the front surface of 1). Therefore, most of the light introduced into the light guide plate (11) is captured by the diffusion plate (22) and diffused. The diffused light is further applied to the LCD panel (10) while reciprocating up and down in the light guide plate (11) between the diffusion plate (21) and the reflection plate (31), as in the first embodiment. Now, it moves in the left-right direction of the figure while decreasing. Then, a part is leaked from the condenser lens (30).

Here, as in the first embodiment, since the refractive index of the acrylic plate, which is the light guide plate (11), is larger than the refractive index of air, the light in the main traveling direction of light in the light guide plate (11) is not changed. The inclination is smaller than the rotation angle of the light source (20). In the present invention, as described above, since the main traveling direction of the light introduced into the light guide plate (11) is not parallel to the main plane of the light guide plate (11), the reflection plate (31) or the diffusion plate ( LCD panel (10) with large amount of capture in 21)
The irradiation light amount to the light is increased, while the condenser lens (30)
The amount of leakage from the air has been reduced. Therefore, as in the first embodiment, a display screen with high light use efficiency, a sufficiently bright display screen even with a relatively small amount of light, and reduced power consumption can be obtained.

Incidentally, the rotatable movable condenser lens (30) and the rotatable movable light source (20) described in the first embodiment.
Can be used together in one LCD.
In this case, the lighting efficiency can be maximized by adjusting the angle of the condenser lens (30) and the angle of the light source (20) according to the situation of external light. FIG.
Next, a side sectional view of an LCD according to a third embodiment of the present invention is shown. In the present embodiment, as in the first embodiment, the condenser lens (30) is rotatable up and down, but the air guide is provided between the reflector (31) and the diffuser (21). It is a layer (12). For this reason, as shown in FIGS. 3B and 3C, light guided obliquely upward or downward from the condenser lens (30) does not change the main traveling direction of light. The light is introduced into the air light guide layer (12), and enters the reflection plate (31) or the diffusion plate (21).
Caught. That is, as in the first embodiment, when the light taken in from the condenser lens (30) is incident on the light guide plate (11), it is not refracted and the rotation angle of the condenser lens (30) is changed. Is directly reflected in the main traveling direction of light in the air light guide layer (12). Therefore, as compared with the first embodiment, the rotation angle of the condenser lens (30) is substantially increased, and the light use efficiency is further improved.

FIG. 4 is a side sectional view of an LCD according to a fourth embodiment of the present invention. In the present embodiment, as in the second embodiment, the light source (20) is rotatable up and down, but between the reflecting plate (31) and the diffusing plate (21),
It is an air light guide layer (12). For this reason, FIG.
As shown in FIG. 4B and FIG. 4C, the light guided obliquely upward or downward from the light source 20 does not change the main traveling direction of the light and does not change the main light traveling direction. And enters the reflection plate (31) or the diffusion plate (21) and is caught. That is, as in the second embodiment, the light emitted from the light source (20) is applied to the light guide plate (11).
When the light is incident on the light guide layer, the light is not refracted, and the rotation angle of the light source (20) is directly reflected in the main traveling direction of the light in the air guide layer (12). Therefore, compared to the second embodiment,
The rotation angle of the light source (20) is substantially increased, and the light use efficiency is further enhanced.

[0024]

As is apparent from the above description, in a liquid crystal display device provided with a condensing unit for taking in external light and / or a light source for emitting light, the condensing unit and / or the light source can be rotated. By doing so, it becomes possible to set the condensing part to an optimum angle according to the position of external light,
The amount of light collected was increased. In addition, the main traveling direction of the light introduced from the light condensing unit and / or the light source to the light guide unit is inclined with respect to the main plane of the light guide unit, and the amount of light trapped on the front and back surfaces of the light guide unit is large. In other words, the efficiency of light utilization has been increased. In addition, we reduce use frequency of light source,
Alternatively, the light emission luminance of the light source can be reduced, and the total power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an LCD according to a first embodiment of the present invention.

FIG. 2 is a side sectional view of an LCD according to a second embodiment of the present invention.

FIG. 3 is a side sectional view of an LCD according to a third embodiment of the present invention.

FIG. 4 is a side sectional view of an LCD according to a fourth embodiment of the present invention.

FIG. 5 is a side sectional view of a conventional LCD.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 LCD panel 20 Light source 30 Condensing lens 40 Case 11 Light guide plate 12 Air guide layer 21 Diffusion plate 31 Reflection plate 201 Reflector 301,202 Rotation axis

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G09F 9/00 336 G09F 9/00 336J (72) Inventor Makoto Shimizu 2-5-5 Keihanhondori Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (5)

[Claims] 1. A liquid crystal display panel in which liquid crystal is sealed between a pair of transparent electrode substrates having predetermined electrodes formed on opposing surfaces, and facing the liquid crystal display panel corresponding to a display section of the liquid crystal display panel. A light guide section provided with a reflective layer on the back side opposite to the front face, a light guide section for connecting the light guide section and an optical path, and a light collecting section for taking in external light and / or a light source section for emitting light;
An illumination section for irradiating the liquid crystal display panel with light, wherein the light condensing section and / or the light source section are controlled such that a main emission direction of the light is rotatably movable, and The liquid crystal display device according to claim 1, wherein a main traveling direction of the light introduced therein is made non-parallel and non-perpendicular to a main plane of the light guide. 2. The light collector according to claim 1, wherein the light collector has a partial cylindrical shape having a rectangular side plane, and the side plane is arranged to face a side surface of the light guide plate. The angle formed between the light plate and the side surface is controlled.
The liquid crystal display device as described in the above. 3. The liquid crystal display device according to claim 3, wherein the light condensing part includes the light guiding part and a light condensing lens. 4. The liquid crystal display device according to claim 1, wherein the light guide plate is an air light guide layer. 5. The liquid crystal display device according to claim 1, wherein the light condensing portion protrudes from behind the liquid crystal display device.