JPH11311779A - Liquid crystal display device provided with light condensing mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize display with high luminance and high contrast ratio by nearly aligning the maximum luminance direction of a lighting part with the preferential visual angle direction of a liquid crystal display panel. SOLUTION: A window 51 for lighting is opened in a housing 50 so that a condensing lens 30 may peep out to the outside and a light transmission plate 20 is protruded in parallel from an area just under the LCD panel 10 on a side surface along the lens 30. The focus directions of the lens 30 and the reflector 41 of a light source are turned downward from a plane direction, and the light introduced to the plate 20 from them is easily caught by a reflecting plate 22. The focus direction of the lens sheet 22 is controlled to a direction inclined from a normal direction, and the maximum luminance direction BL of a backlight is adjusted to the preferential visual angle direction DIR of the LCD panel 10. As a result, the luminance is the highest and the contrast ratio is the maximum, so that the best display is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display (L).
More particularly, the present invention relates to a liquid crystal display device having a light-condensing mechanism and reducing power consumption of a backlight.

[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 portable use,
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 is a side sectional view of such an LCD. (100) is an LCD panel, (200) is a light guide plate,
(201) is a diffusion plate, (202) is a lens sheet, (2)
03) is a reflector, (300) is a condenser lens, (400)
Is a light source, and (500) is a housing for holding these units. The light source (400) has a reflector (40) behind it.
An acrylic resin or the like is used for the fluorescent lamp and the light guide plate (200) provided with 1). Diffusing plate (201) and reflecting plate (2
03) are provided on the front surface and the back surface of the light guide plate (200), respectively. The light guide plate (200) is integrated by performing diffusion processing and irregular reflection processing. These light guide plates (2
00), diffusion plate (201), lens sheet (202),
Reflector (203), condenser lens (300) and light source (4
00) constitutes a backlight which is an illuminating unit.
As the condenser lens (300), a lens separate from the light guide plate (200) or a lens processed integrally with the light guide plate (200) is used. Also, the housing (500) includes:
The daylighting window (501) is opened, and the condenser lens (30) is opened.
0) peeks outside.

The light emitted from the light source (300) or the light taken in from the condenser lens (400) is transmitted to the light guide plate (200) and the diffusion plate (2) on the front surface thereof.
01) and the reflection plate (2
03) Diffusely reflected. The light reflected by the reflection plate (203) travels through the light guide plate (200) and is diffused by the diffusion plate (201).
And is spread. A part of the light diffused by the diffusion plate (201) is directed in the normal direction by the lens sheet (202), and is radiated vertically to the LCD panel (200). The rest is returned to the light guide plate (200) again and reflected by the reflector (203). Thus, the light source (40
0) or the light guide plate (20) from the condenser lens (300).
0) is introduced into the diffusion plate (201) and the reflection plate (2).
03), attenuating while going back and forth, and proceeding in the parallel direction. The LCD panel (100) cannot emit light by itself, and by illuminating from the back in this way, the transmittance is controlled to a desired transmittance, and the display screen set at a recognizable preceding stage has a distribution of transmitted light. Is visualized as

In this configuration, in an environment where the outside light is abundant such as a sunny outdoors, the light source (400) is turned off and the light is illuminated only by the light from the condenser lens (300), and the outside light such as indoors is used. In a state where is insufficient, it is possible to use the light source (400) to obtain a bright display screen by turning on the light source (400). Accordingly, the light source (400) having large power consumption is not used, and only the driving power of the LCD panel (100) is used, so that the total power consumption is reduced.

[0006]

In the LCD shown in FIG. 5, the lens sheet (202) includes a diffusion plate (201).
It is designed to emit the light sent from the normal direction. That is, the backlight light always vertically enters the LCD panel (100) regardless of the position of the external light.
Therefore, the intensity of the transmitted light emitted from the LCD panel (100) becomes maximum in the maximum luminance direction BL in FIG. On the other hand, the preferential viewing angle direction DIR of the LCD panel (100), that is, the direction in which the contrast ratio is maximized, is inclined from the normal direction and is different from the maximum luminance direction BL. Thus, the preferred viewing angle direction DI of the LCD
If R and the maximum luminance direction of the backlight are different,
The luminance is insufficient when viewed from the priority viewing angle direction DIR of the LCD panel (100), and the contrast ratio is low when viewed from the maximum luminance direction BL of the backlight. In any case, the best display can be obtained. Did not.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve this problem, and a liquid crystal in which liquid crystal is sealed between a pair of transparent electrode substrates having electrodes for driving liquid crystal formed on opposing surfaces. It is placed behind the display panel and the LCD panel,
A liquid crystal display device with a light-collecting mechanism having an illuminating unit that irradiates the liquid crystal display panel with light by taking in external light, wherein a maximum luminance direction of the illuminating unit and a preferred viewing angle direction of the liquid crystal display panel are substantially equal to each other. It is a configuration that I do.

As a result, a display with high luminance and a high contrast ratio can be obtained.

Also, a liquid crystal display panel in which liquid crystal is sealed between a pair of transparent electrode substrates having electrodes for driving liquid crystal formed on the opposing surfaces, and a collecting plate placed behind the liquid crystal display panel and taking in external light. An illuminating unit having a light unit for irradiating the liquid crystal display panel with light, wherein the light collecting unit is intuitive with a direction in which the viewing angle of the liquid crystal display panel is the widest. This is a configuration provided on the side to be formed.

Accordingly, even if the position of the external light source changes,
Since the maximum luminance direction of the illuminating unit changes within the viewing angle range, the dependence on the position of the external light source is reduced.

[0011]

FIG. 1 is a side sectional view of an LCD according to a first embodiment of the present invention. LCD panel (1
0), a light guide plate (20), a diffusion plate (21), a lens sheet (22), a reflection plate (23), a condenser lens (30), a light source (40), and a housing for housing and holding these units (50). An acrylic plate or the like is used for the light guide plate (20). The condenser lens (30) has a rectangular side surface and a partial circular cross section. These light guide plates (2
0), the diffusion plate (21), the lens sheet (22), the reflection plate (23), the condenser lens (30), and the light source (40) constitute a backlight which is an illumination unit. Further, a window (51) for lighting is opened in the housing (50) so that the condenser lens (30) can be seen outside. The condenser lens (30) extends in a direction perpendicular to the paper surface along the side of the LCD, and has a semicircular cross section as shown in the figure. The light guide plate (20) protrudes in parallel from the area directly below the LCD panel (10) on the side along the condenser lens (30). The focal directions of the condenser lens (30) and the reflector (41) of the light source are directed downward from the plane direction, and light introduced into the light guide plate (20) from these is easily captured by the reflection plate (22). Then e4
The use efficiency of e4e4f5 has been improved.

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 driving 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 focal direction of the lens sheet (22) is controlled in a direction inclined from the normal direction, so that the maximum luminance direction BL of the backlight matches the preferred viewing angle direction DIR of the LCD panel (10). . As a result, the highest luminance and the highest contrast ratio are obtained, and the best display is obtained.

FIG. 2 is a side sectional view of an LCD according to a second embodiment of the present invention. FIG. 3 is also a plan view. In the present embodiment, the side where the condenser lens (30) is provided is a side that is perpendicular to the direction V at which the viewing angle of the LCD panel (10) is the widest. Here, the viewing angle is a viewing angle range θ in which a predetermined contrast ratio or more is obtained, in other words, an allowable viewing angle range including the preferential viewing angle direction DIR. In FIG. 3, the equal contrast ratio lines connecting the viewing angles at which a predetermined contrast ratio is obtained are indicated by wavy lines. The viewing angle area surrounded by the equal contrast ratio line is the viewing angle. The viewing angle is larger in the vertical direction V than in the horizontal direction H on the paper. Therefore, the condenser lens (30) is provided on the upper side (or the lower side). The direction is L
This is the direction such as the viewing angle when viewed from the CD surface.

Although the maximum luminance direction BL can be specified to some extent by the lens sheet (22), when the position of an external light source such as the sun or an electric lamp is changed, the main direction of the light actually emitted from the backlight, that is, Maximum irradiation direction BR
May deviate from the maximum luminance direction BL. For example,
As shown in FIG. 4, when the external light source (46) is positioned at a certain high angle with respect to the LCD (50) plane, the maximum irradiation direction BR 1 also has a high angle, but the external light source (4
7) is positioned at a low angle, the angle of the maximum irradiation direction BR2 also becomes small. The viewing angle range COT1 in the V direction cross section in FIG. 3 is the viewing angle range C in the H direction cross section.
Wider than OT2. Therefore, in the present embodiment, as shown in FIG. 3, the external light source (4) is provided by providing the condenser lens (30) on the side perpendicular to the direction V in which the viewing angle increases.
6, 47), even if the maximum irradiation directions BR1 and BR2 change depending on the position, they fall within the viewing angle range COT1. Thus, the display screen is observed with a high luminance and a high contrast ratio even when viewed from any direction of BR1 and BR2. On the other hand, if the condenser lens (30) is provided on a side perpendicular to the direction H in which the viewing angle decreases, the viewing angle range COT2 becomes narrow.
In the case of the external light source (46), since the maximum irradiation direction BR1 falls within the viewing angle range COT2, the visibility from the BR1 direction is good. However, in the case of the external light source (47), the maximum irradiation direction BR2 is the viewing angle. Since it is out of range COT2, BR2
Viewing from the direction has a high luminance but a low contrast ratio.

[0016]

As is apparent from the above description, in a liquid crystal display device provided with an illuminating section having a condensing section for taking in external light, the maximum luminance direction of the illuminating section and the preferred viewing angle direction of the liquid crystal display panel are matched. As a result, the best display with high luminance and high contrast ratio was obtained. In addition, by providing the condensing part on the side where the viewing angle of the liquid crystal display panel is perpendicular to the widest direction, regardless of the angle of incidence of external light to the condensing part, good brightness and high contrast ratio can be obtained. The display was obtained.

[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 plan view of an LCD according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between an external light source of the LCD and a maximum irradiation direction.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 LCD panel 20 Light guide plate 21 Diffusion plate 22 Reflection plate 30 Condensing lens 40 Light source 50 Housing

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Makoto Shimizu 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A liquid crystal display panel in which liquid crystal is sealed between a pair of transparent electrode substrates having liquid crystal driving electrodes formed on opposing surfaces, and a liquid crystal display panel placed behind the liquid crystal display panel to receive external light. An illuminating unit for irradiating the liquid crystal display panel with light, wherein the liquid crystal display device with a light-condensing mechanism has a maximum luminance direction of the illuminating unit and a preferred viewing angle direction of the liquid crystal display panel substantially coincide with each other. Characteristic liquid crystal display device with light collecting mechanism. 2. A liquid crystal display panel in which liquid crystal is sealed between a pair of transparent electrode substrates each having an electrode for driving liquid crystal formed on an opposing surface, and a collector disposed behind the liquid crystal display panel to receive external light. An illuminating unit having a light unit for irradiating the liquid crystal display panel with light, wherein the light collecting unit has a right angle with a direction in which the viewing angle of the liquid crystal display panel is the widest. A liquid crystal display device with a light-condensing mechanism, wherein the liquid crystal display device is provided on a side formed.