JPH1164640A - Lighting device, liquid crystal device and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the contrast with a low power consumption by making the visual direction of a body to be illuminated and incident directions of incident lights from a light source to a light transmission plate roughly coincident. SOLUTION: This illuminator is constituted of a light transmission plate 1 on which projected parts 5 or recessed parts having light diffusing shapes are formed and a point light source 2 consisting of four pieces of LEDs(light emitting dioides) arranged at the end face of the light transmission plate 1 and is arranged at the front side of a liquid crystal panel 20 being the body to be illuminated. Then, directions 3 with which luminous fluxes of LEDs entering to the light transmission plate 1 become parallel are made to become roughly parallel with a visual direction 10 by arranging the illuminator so that the LEDs come to be at the inner side of the light transmission plate 1 when they are seen from the visual direction 10. The visual direction means a direction from which information displayed on the liquid crystal panel 20 can be read. This liquid crystal device normally performs the display as a reflection type liquid crystal panel with surrounding lights. Besides, in an environment where the surrounding is dark, the liquid crystal panel 20 is illuminated with lights emitted from the under surface of the light transmission plate 1 by lighting the LEDs arranged in the plate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lighting device, a liquid crystal device having a lighting function, and an electronic apparatus equipped with the liquid crystal device having a lighting function.

[0002]

2. Description of the Related Art Conventionally, as a liquid crystal display device in a bright environment, as shown in FIG.
A reflective liquid crystal display device in which a reflective plate 102 is disposed on the back surface of the liquid crystal display device 1 has been used. Further, as a liquid crystal display device having good contrast, as shown in FIG.
1, a transmissive liquid crystal display device is used in which a surface illumination device 103 is disposed as a backlight and illumination is always performed from the rear surface.

Further, as a liquid crystal display device which can be used regardless of whether the surroundings are bright or dark, as shown in FIG. 23, a transflective reflector 104 and a surface illuminating device 103 are arranged on the back of a liquid crystal display panel 101 as a backlight. A transmission type liquid crystal display device has been used. In this case, external light is used for display in a bright environment, and a backlight is turned on in a dark environment. (For example, JP-A-57-049271, JP-A-57-0549)
26, JP-A-58-095780, etc.).

[0004]

Recently, portable telephones and PDs have been developed.
Small information devices such as A are required to be thinner and lighter and have lower power consumption. However, the conventional transmissive liquid crystal display device has a problem that the contrast is good, but the backlight is always lit as illumination, so that the power consumption is large, and when it is mounted on a mobile phone, it cannot be used for a long time.

Further, the conventional reflective liquid crystal display device consumes less power than the transmissive liquid crystal display device because it is not necessary to turn on the light source. However, the display is dark in a dark environment and cannot be used. Had. Further, the conventional transflective liquid crystal display device has a problem that the display in a bright environment is dark because the transflective plate is used.

Accordingly, the present invention solves the above-mentioned conventional problems, and provides an illumination device, a liquid crystal device having an illumination function, and a liquid crystal device having an illumination function which do not degrade the display function of a reflection type liquid crystal device. The present invention relates to an electronic device equipped with.

[0007]

According to the present invention, there is provided an illuminating device comprising: a light guide plate disposed on a front surface of an illuminated body and formed with a plurality of convex portions or concave portions for diffusing light on the surface; In a lighting device having a light source disposed on an end face side, a viewing direction of the illuminated body and an incident direction of light incident on the light guide plate from the light source are substantially matched.

With such a configuration, the direction of light propagating through the light guide plate and the observation direction substantially coincide with each other.
A bright display is obtained.

In addition, the incident direction and the viewing direction are set to coincide with each other, and the light source is disposed on the near side and / or the back side of the light guide plate with respect to the viewing direction of the illuminated body. Configuration. As the light source used here, a point light source or a rod light source can be used.

[0010] Further, in order to emit light from the light source in the direction in which the illuminated object is arranged, the convex portion or the concave portion is formed on a surface of the light guide plate different from the surface facing the illuminated object. Alternatively, it is necessary to form the projection on the surface of the light guide plate facing the object to be illuminated.

Further, in order to efficiently emit light from the light source propagating through the light guide plate toward the object to be illuminated, a reflection member is disposed on an end face of the light guide plate.

Further, the liquid crystal device of the present invention comprises: a liquid crystal panel; a light guide plate disposed on the front surface of the liquid crystal panel and having a plurality of convex portions or concave portions formed on the surface to diffuse light; In a liquid crystal device having a light source disposed on an end face side, a viewing direction of the liquid crystal panel is substantially matched with an incident direction of light incident on the light guide plate from the light source.

With such a configuration, since the direction of light propagating through the light guide plate and the observation direction substantially match, a bright display can be obtained when the light source is turned on.

Further, an incident direction of light incident on the light guide plate from the light source is substantially parallel to an extending direction of at least one electrode formed on the liquid crystal panel.

Further, a part of the electrodes formed on the liquid crystal panel is formed of a material having a reflection characteristic, or a reflection layer formed of a material having a reflection characteristic is disposed on the back side of the liquid crystal panel. Configuration.

By mounting such a liquid crystal device on an electronic device, it can be used for a mobile phone, a clock, and the like.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1 and 2 are views showing the structure of a first embodiment of the present invention. FIG. 1 is a sectional view, and FIG. 2 is a plan view. The illuminating device shown in FIG. 1 includes a light guide plate 1 on which a convex portion 5 having a light diffusing shape is formed, and four point light sources 2 of LEDs (light emitting diodes) having a luminous intensity of 16 mcd disposed on end faces of the light guide plate 1. Are arranged on the front surface of the liquid crystal panel 20 which is an illuminated body.

The liquid crystal panel 20 has upper and lower substrates 22 and 23 sandwiching a liquid crystal layer 21, a pair of polarizing plates 24 and 25 disposed outside thereof, and a phase conversion means sandwiched between the polarizing plate and the liquid crystal layer. This is a reflection type liquid crystal panel that has a phase difference plate 26 and a reflection plate 27 as reflection means disposed outside the polarizing plate, and uses external light. As shown in FIG. 2, in the liquid crystal panel 20, a direction (or a direction perpendicular to) a side perpendicular to the horizontal direction in front of the liquid crystal panel is the viewing direction 10,
The alignment state, such as the twist angle of the liquid crystal molecules in the liquid crystal layer, the rubbing direction for rubbing, and the like, and the axial conditions of each member such as a retardation plate and a polarizing plate were set in accordance with the viewing direction.

Then, when viewed from the viewing direction 10, LE
D is located on the back side of the light guide plate 1, and the direction 3 in which the average of the luminous flux of the LED incident on the light guide plate 1 is the viewing direction 10.
And was made substantially parallel. The viewing direction is a direction in which information such as characters and numbers displayed on the liquid crystal panel can be read. In many cases, the viewing direction is set in a direction substantially perpendicular to (or perpendicular to) the horizontal side in front of the liquid crystal panel, but is set in a direction crossing the horizontal side in front of the liquid crystal panel by a predetermined angle. In some cases.

The light guide plate 1 was a transparent acrylic resin plate having a thickness of 1 mm and a refractive index of 1.49. On a surface different from the surface facing the liquid crystal panel 20, a convex portion 5a made of a conical protrusion with a bottom diameter of 50 μm, a height of 11.6 μm, and a vertex angle of about 130 degrees was formed as shown in FIG. And FIG.
As shown in FIG. At this time, the ratio of the area of the projection to the area of the illumination part of the light guide plate was about 10%.

In the present embodiment, the convex portion is provided on a surface different from the surface facing the liquid crystal panel. However, the shape of the convex portion can be set to a cone, a pyramid, a hemisphere, or the like.
In addition, it is also possible to form a recess with such a shape. Furthermore, a conical, pyramidal, or hemispherical convex portion can be formed on the surface facing the liquid crystal panel. As described above, it is possible to form a convex portion or a concave portion on the light guide plate as appropriate, and efficiently irradiate the illuminated body with light. The same applies to the following embodiments.

The light guide plate 1 has a material having a refractive index of 1.4.
9, the critical angle inside the light guide plate is about 42 degrees. The light beam incident on the light guide plate 1 from the end face 7 of the light guide plate 1 is
When the angle of incidence with respect to the surface of
As shown by the light ray 6b, total reflection is repeated in the light guide plate 1. After that, the light reflected on each surface of the convex portion 5 is applied to the light guide plate 1.
When the incident angle with respect to the surface on the liquid crystal panel 20 side becomes approximately 42 degrees or less, the light exits from the light guide plate 1 and can illuminate the liquid crystal panel 20.

Since the light guide plate 1 is a transparent flat plate, the display is usually performed with ambient light as a reflection type liquid crystal panel. Such a liquid crystal device according to the present application has a display of substantially the same brightness and contrast as a reflection type liquid crystal display device in which a conventional illumination device is not arranged on the front surface of the liquid crystal display device.

In an environment where the surroundings are dark, the liquid crystal panel 20 can be illuminated with light emitted from the lower surface of the light guide plate 1 by turning on an LED disposed on the light guide plate, and the same as in a bright environment. Was obtained.

FIG. 4 schematically shows a direction in which a display from an illuminated object such as a liquid crystal panel exits through the light guide plate. The direction OD is the direction in which light exits through the light guide plate.
The angle between the vertical direction and the direction OD with respect to the plane of the liquid crystal device was defined as an angle β. In addition, a position E which is perpendicular to the position of D on the plane of the liquid crystal device, and a direction orthogonal to the horizontal side in front of the liquid crystal panel 20 on the surface of the liquid crystal device 20 (or a direction perpendicular thereto); Is defined as α.

Assuming that the direction orthogonal to the front side of the liquid crystal panel 20 is the viewing direction, the viewing direction of the display of a small information device such as a mobile phone or a PDA is 20 ° left and right as shown in FIG. The range A is 30 ° on the side and 10 ° on the back side. Among them, especially 10 ° to the left and right, 20 ° to the front, 0 ° to the back
There are many directions in the range B indicated by oblique lines (front).

In a small-sized information device such as a portable telephone, which looks at a display while holding it, the viewing angle is adjusted so that the display is most easily viewed by an observer. In addition, an object that is used by placing it on a desk or the like has a structure in which the angle of the display unit can be changed. Since the display unit is turned in a direction in which it is easy to see, the range of the line of sight for viewing the display is narrow.

In this embodiment, the direction perpendicular to the front side of the liquid crystal panel 20 is the viewing direction, so that the viewing direction is α = 0 °.
And the direction of the incident light from the LED is α = 180 °. FIG. 6 shows the angle characteristics of the brightness (luminance) of the display of the liquid crystal device according to the present embodiment when the LED is turned on for illumination.
FIG. The brightness at β = 0 ° (front) is 1.8 cd / m ² , and the isoluminance curve is 2 cd from the inside.
/ M ² , 4 cd / m ² , 6 cd / m ² , 10 cd / m ²
It is. α = 180 ° and β = 20 ° are the darkest,
Regions of the same brightness are distributed in an elliptical shape centered there.

Also, the display becomes brighter as the inclination from the front increases, and the direction of α = 0 ° which is the viewing direction is the brightest even if the inclination angle β from the front is the same.

When the ranges in the line of sight shown in FIG. 5 are overlapped,
It can be seen that the range B of the viewing direction in which the display is viewed can be set to a portion where the display is brightest in an area within an angle of 20 ° from the front of the liquid crystal display device.

When the LED is turned on, light is emitted from the upper surface of the light guide plate 1 to the observer side. This is because the light that has been repeatedly totally reflected in the light guide plate 1 is transmitted without being reflected because the incident angle is smaller than the critical angle at the convex portion 5a, or the light comes in contact with the surface of the light guide plate 1 and the convex portion 5a. This is the scattered light at the intersections and at the vertices of the cone, and appears to the observer as a bright spot. This light has little effect on the display because it is weak in the front, but the light is emitted more strongly as the angle β becomes larger, which affects the display. When the light of the bright spot becomes strong and overlaps the display, the contrast is lost and the display cannot be read.

In the case of the present embodiment, the range in which the light emitted from the upper surface of the light guide plate 1 to the observer side becomes intense and the display cannot be read is the range C of the oblique lattice shown in FIG. The range A in the viewing direction in which the display is viewed is inside the region C where the display cannot be read due to the light emitted from the upper surface of the light guide plate to the observer side, and thus does not hinder reading of the display.

As the transparent material forming the light guide plate 1, other than an acrylic resin, a transparent resin such as a polycarbonate resin or an amorphous polyolefin resin, an inorganic transparent material such as glass, or a composite thereof may be used. Examples of the method of forming the projecting projections 5 include injection molding, thermosetting resin, photocurable resin, etching, and joining a film or resin layer on a transparent resin or a glass flat plate.

Depending on the surrounding environment, the projection 5 as shown in FIG.
Ambient light may be reflected by the surface of a and seen by an observer. This depends on the size of the convex portion 5 and is small enough that the reflection of ambient light is not noticeable to the naked eye.
μm or less is desirable. Further, the thickness is required to be 5 μm or more so that the influence of diffraction of visible light does not occur. Furthermore, the size is about 10 μm or more and 100 for convenience in manufacturing.
μm or less is desirable.

The efficiency of illumination increases as the area ratio of the projections to the area of the illuminating portion of the light guide plate increases, but the visibility decreases because the parallel light transmittance in the direction perpendicular to the light guide plate decreases. If it exceeds 50%, it is not practical. On the other hand, if it is too small, the lighting efficiency is reduced, so that 5% or more is necessary. Therefore, the area ratio of the convex portion to the area of the illumination portion of the light guide plate is desirably 5% to 50%.

Further, in addition to the conical shape shown in FIG. 3, the convex portion may have a hemispherical convex shape as shown in FIG. Further, a conical concave shape as shown in FIG. 8 or a hemispherical concave shape as shown in FIG. 9 may be used. Further, the light guide plate facing the liquid crystal device may have a cylindrical convex shape as shown in FIG. 10 or a cylindrical concave shape as shown in FIG.

With the above arrangement, even when the present illumination device is disposed in front of a reflective liquid crystal panel, when the surrounding environment is sufficiently bright, substantially the same display as the conventional reflective liquid crystal display device can be obtained. However, in a dark environment, the LED can be turned on to illuminate the liquid crystal device, and the liquid crystal device has substantially the same contrast as when the surrounding environment is sufficiently bright. Here, it is needless to say that the liquid crystal device is not limited to the structure used in this embodiment. (Embodiment 2) FIGS. 12 and 13 are views showing the configuration of the second embodiment of the present invention, and FIG. FIG. 13 shows a plan view. The illuminating device shown in FIG. 1 includes a light guide plate 1 on which a light-diffusing convex portion 5 is formed, four point light sources 2 of 16 mcd LED at end faces of the light guide plate 1, and four end faces of the light guide plate 1. And is disposed on the front surface of the liquid crystal panel 20, which is an illuminated body.

As the liquid crystal panel 20, the reflection type liquid crystal panel used in Example 1 was used. As shown in FIG. 13, the direction perpendicular to the front side of the liquid crystal panel 20 was set as the viewing direction 10. The alignment state of the liquid crystal layer and the axial conditions of each member were set according to the observation direction. This is similarly set as described in the first embodiment. Then, when viewed from the viewing direction 10, the LEDs are arranged so as to be on the back side of the light guide plate 1, and the direction 3 in which the average light flux of the LED incident on the light guide plate 1 is substantially parallel to the viewing direction 10. I did it. The direction in which light is emitted from the light source to the light guide plate substantially coincides with the propagation direction of light propagating through the light guide plate. Furthermore, the direction in which the emission intensity of the light source is the highest is almost the same as the direction of incidence of light,
It is also possible to set according to the light emission intensity of the light source.
This is the same in the first embodiment and the subsequent embodiments.

As the light guide plate 1, a transparent acrylic resin flat plate having the light-diffusing convex portions 5 used in the first embodiment was used. The reflective member 4 was attached to the end surface of the light guide plate 1 via an adhesive using a film on which aluminum was deposited. Since the reflection member 4 returns the light beam guided to the inside of the light guide plate 1 and reaching the end face to the inside of the light guide plate 1 again, the illumination efficiency can be improved.

Since the light guide plate 1 is a transparent flat plate, in an environment where the surroundings are bright, display is performed using ambient light as a reflection type liquid crystal device, and almost the same as a conventional reflection type liquid crystal display device in which an illumination device is not arranged in front of the liquid crystal device. Was displayed. Further, in an environment where the surroundings are dark, by turning on the LED, the liquid crystal panel 20 can be illuminated with the light emitted from the lower surface of the light guide plate 1, which is brighter than in the first embodiment. Similar contrast was obtained.

Also in this embodiment, the direction perpendicular to the front side of the liquid crystal panel 20 is the viewing direction, so that the viewing direction is α = 0 °.
And the direction of the incident light from the LED is α = 180 °. FIG. 1 shows an angle characteristic of display brightness (luminance) of the liquid crystal device of the present embodiment when the LED is turned on to perform illumination.
4 shows an isoluminance curve. The brightness at β = 0 ° (front) is 2.4 cd / m ² , and the isoluminance curve is 2 cd from the inside.
/ M ² , 4 cd / m ² , 6 cd / m ² , 10 cd / m ²
It is. In the figure, the region near α = 180 ° and β = 10 ° is the darkest, and the regions of the same brightness are distributed in an elliptical shape with the region as the center.

As in the case of the first embodiment, the display becomes brighter as the inclination from the front increases, and the direction of the visual recognition α = 0 ° becomes the brightest even if the inclination angle β from the front is the same. I have.

When the ranges in the line of sight shown in FIG. 5 are overlapped,
It can be seen that the range B of the viewing direction in which the display is viewed can be set to a portion where the display is brightest in an area within an angle of 20 ° from the front of the liquid crystal device.

Also in this embodiment, when the LED is turned on, light is emitted from the upper surface of the light guide plate 1 to the observer side. In the case of the present embodiment, the range where the light emitted from the upper surface of the light guide plate 1 to the observer side becomes strong and the display cannot be read is as shown in FIG.
This is the range C shown in FIG. Viewing range A in viewing direction
Is located inside the region C where the display cannot be read due to light emitted from the upper surface of the light guide plate toward the observer,
It does not prevent reading the display.

The same results were obtained when a thin film made of aluminum or the like was adhered via a double-sided tape or an adhesive, or a thin film made of aluminum or the like was used as the reflective member.

(Embodiment 3) FIGS. 15 and 16 are views showing a configuration of a third embodiment of the present invention. FIG.
FIG. 16 shows a plan view. The illuminating device shown in FIG. 1 includes a light guide plate 1 in which a convex portion 5 as a light diffusing shape is formed on a surface different from a surface facing a liquid crystal panel, and eight point light sources of LEDs having a luminance of 16 mcd on end surfaces of the light guide plate 1 2 and the reflection members 4 on the four end surfaces of the light guide plate 1, and are arranged on the front surface of the liquid crystal panel 20 which is the object to be illuminated.

As the liquid crystal panel 20, the reflection type liquid crystal panel used in Example 1 was used. As shown in FIG. 16, the direction perpendicular to the front side of the liquid crystal panel 20 is the viewing direction 10, and the alignment state of the liquid crystal layer and the axial conditions of each member are set so as to match the viewing direction 10. And when viewed from the viewing direction 10, LE
D is arranged on the front side and the back side of the light guide plate 1 so as to be four each, so that the average direction 3 of the luminous flux of the LED incident on the light guide plate 1 is substantially parallel to the viewing direction 10. .

As the light guide plate 1, a flat plate made of a transparent acrylic resin having the projections 5 as the light-diffusing projections used in Example 1 was used. The reflective member 4 was attached to the end surface of the light guide plate 1 via an adhesive using a film on which aluminum was deposited. Since the reflection member 4 returns the light beam guided to the inside of the light guide plate 1 and reaching the end face to the inside of the light guide plate 1 again, the illumination efficiency can be improved.

Since the light guide plate 1 is a transparent flat plate, in an environment where the surroundings are bright, it is a reflection type liquid crystal device which performs display with ambient light, and is substantially the same as a conventional reflection type liquid crystal display device in which an illuminating device is not arranged in front of the liquid crystal device. Was displayed.

In an environment where the surroundings are dark, by turning on the LED, the light emitted from the lower surface of the light guide plate 1 is used for the liquid crystal panel 2.
0 could be illuminated, the image became brighter than in Example 2, and the same contrast as in an environment with bright surroundings was obtained.

Also in this embodiment, since the direction perpendicular to the front side of the liquid crystal panel 20 is the viewing direction, the viewing direction is α = 0 °, and the direction of the incident light from the LED is α = 180 °. Accordingly, FIG. 17 shows an angle characteristic of the brightness (luminance) of the display of the liquid crystal display device of the present embodiment when the LED is turned on to perform illumination, with an equal luminance curve. The brightness at β = 0 ° (front) is 4.2 cd / m ² and the isoluminance curve is 5 from the inside.
^{cd / m 2, 10cd / m} 2, 15cd / m 2, 20c
d / m ² .

In the figure, the portion where β = 0 ° is the darkest, and the regions of the same brightness are distributed in an elliptical shape symmetrical in the vertical, horizontal, and horizontal directions with the center as the center. As in the first and second embodiments, the display becomes brighter as the inclination from the front increases, and when the inclination angle β from the front is the same, the viewing directions α = 0 ° and α = 180 ° It is the brightest.

When the ranges in the line-of-sight direction shown in FIG.
It can be seen that the range B of the viewing direction in which the display is viewed can be set to a portion where the display is brightest in an area within an angle of 20 ° from the front of the liquid crystal display device.

Also in this embodiment, when the LED is turned on, light is emitted from the upper surface of the light guide plate 1 to the observer side. In the case of the present embodiment, the range where the light emitted from the upper surface of the light guide plate 1 to the observer side becomes strong and the display cannot be read is as shown in FIG.
This is the range C shown in FIG. Viewing range A in viewing direction
Is located inside the region C where the display cannot be read due to light emitted from the upper surface of the light guide plate toward the observer,
It does not prevent reading the display.

The same result was obtained when a film other than aluminum was vapor-deposited or a thin plate made of aluminum or the like was adhered via a double-sided tape or an adhesive, or a thin film of aluminum or the like was vapor-deposited as a reflection member.

(Embodiment 4) FIGS. 18 and 19 are views showing the structure of a fourth embodiment of the present invention, and FIG.
FIG. 13 shows a plan view. The illuminating device shown in FIG. 1 includes a light guide plate 1 in which a convex portion is formed as a light diffusing shape on a surface opposite to a surface facing a liquid crystal panel, and a cold cathode tube as a rod-like light source 8 on an end surface of the light guide plate 1. The light guide plate 1 is composed of the reflection members 4 on the four end faces, and is disposed on the front surface of the liquid crystal panel 20 which is the object to be illuminated. As the liquid crystal panel 20, the reflection type liquid crystal panel used in Example 1 was used.

As shown in FIG. 19, the direction perpendicular to the front side of the liquid crystal panel 20 is the viewing direction 10, and the alignment state of the liquid crystal layer and the axial condition of each member are set so as to correspond to the viewing direction. When viewed from the viewing direction 10, the cold-cathode tube is disposed on the back side of the light guide plate 1, and the direction 3 in which the average light flux of the cold-cathode tube incident on the light guide plate 1 is substantially parallel to the viewing direction 10. It was made to become.

As the light guide plate 1, a transparent acrylic resin flat plate having the light-diffusing convex portions 5 used in Example 1 was used. The reflective member 4 was attached to the end surface of the light guide plate 1 via an adhesive using a film on which aluminum was deposited. Since the reflection member 4 returns the light beam guided to the inside of the light guide plate 1 and reaching the end face to the inside of the light guide plate 1 again, the illumination efficiency can be improved.

The reflecting member 9 is made of a film on which aluminum is vapor-deposited, and the light guide plate 1 disposed so as to cover the end face of the light guide plate 1 and the cold cathode tube is a transparent flat plate. The display was performed using ambient light, and the display was almost the same as that of a conventional reflective liquid crystal display device in which the illumination device was not disposed in front of the liquid crystal panel.

Further, in an environment where the surroundings are dark, the liquid crystal panel 20 can be illuminated with light emitted from the lower surface of the light guide plate 1 by turning on the cold-cathode tubes, and the surroundings become brighter than in the third embodiment. The same contrast as in a bright environment was obtained.

Also in this embodiment, since the direction perpendicular to the side in front of the liquid crystal panel 20 is the viewing direction, the viewing direction is α = 0 °, and the direction of the incident light from the LED is α = 180 °. The brightness at β = 0 ° (front) of the display of the liquid crystal display device of the present embodiment when the cold cathode tube is lit and illuminated is 1
20 cd / m ² , and the shape of the angular characteristic of the brightness is the darkest in the area of α = 180 ° and β = 10 ° as in the case of the second embodiment, and the area of the same brightness is an ellipse centered there. It is distributed in a shape. As in the case of the second embodiment, the display becomes brighter as the inclination from the front increases, and the direction of α = 0 °, which is the viewing direction, is brightest even if the inclination angle β from the front is the same.

For this reason, the range B in the viewing direction for viewing the display shown in FIG. 5 can be set to a portion where the display is brightest in an area within an angle of 20 ° from the front of the liquid crystal display device.

Also in this embodiment, when the cold-cathode tube is turned on, light is emitted from the upper surface of the light guide plate 1 to the observer side. However, the range of the viewing direction in which the display is viewed is inside the region where the display cannot be read due to the light emitted from the upper surface of the light guide plate toward the observer, so that it does not hinder the reading of the display.

In the above-described first to fourth embodiments, the embodiment is described using the light guide plate having the convex portion formed on the surface different from the surface facing the liquid crystal panel. However, the present invention faces the liquid crystal panel. A light guide plate having a convex portion formed on the surface may be used. Also,
It is also possible to form the convex portion for diffusing light so as to be a concave portion while having a property of irradiating the liquid crystal panel with light from a light source.

Embodiment 5 FIG. 20 shows an example in which the liquid crystal device of the present invention is used in a mobile phone. Display unit 50 of mobile phone 40
The lighting device of Example 4 and a liquid crystal panel were used. When external light was used, a brighter display was obtained than with a display unit using a conventional liquid crystal display device using a transflective reflector. In addition, even when the lighting device is turned on, the same contrast as when using external light can be obtained, so that the mobile phone can be used without trouble even in a dark environment where external light is not sufficient.

When the liquid crystal display device of the present invention is used not only for a portable telephone but also for an electronic device such as a portable electronic device such as an electronic organizer or a measuring device, a bright display can be obtained when external light is used. An electronic device that can obtain the same contrast as when using external light even when is turned on.

[0068]

According to the present invention, as described above,
It is possible to provide a thin surface illumination suitable for a notice board, a display body, and the like using external light. Further, it is possible to provide a low-power-consumption and high-contrast liquid crystal display device in which the same contrast as when external light is used can be obtained even when the lighting device is turned on. Furthermore, in applications that require power saving, such as portable electronic devices, the display can be used with the lighting turned off in bright places, and can be used in dark environments without reducing the contrast even when the lighting is on, with low power consumption and high contrast display. An electronic device having a unit can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view showing an embodiment of the present invention.

FIG. 3 is an explanatory view of a projection having a convex shape according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram of angles α and β.

FIG. 5 is an explanatory diagram of a distribution of a line of sight of an observer.

FIG. 6 is an explanatory diagram of angle characteristics of display brightness in the embodiment of the present invention.

FIG. 7 is an explanatory diagram of a projection having a convex shape according to the embodiment of the present invention.

FIG. 8 is an explanatory view of a concave shape in the embodiment of the present invention.

FIG. 9 is an explanatory view of a concave shape in the embodiment of the present invention.

FIG. 10 is an explanatory diagram of a projection having a convex shape according to the embodiment of the present invention.

FIG. 11 is an explanatory view of a concave shape in the embodiment of the present invention.

FIG. 12 is a sectional view showing an embodiment of the present invention.

FIG. 13 is a plan view showing an embodiment of the present invention.

FIG. 14 is an explanatory diagram of angle characteristics of display brightness in the embodiment of the present invention.

FIG. 15 is a sectional view showing an embodiment of the present invention.

FIG. 16 is a plan view showing an embodiment of the present invention.

FIG. 17 is an explanatory diagram of angle characteristics of display brightness in the embodiment of the present invention.

FIG. 18 is a sectional view showing an embodiment of the present invention.

FIG. 19 is a plan view showing an embodiment of the present invention.

FIG. 20 is a diagram showing an example of the present invention.

FIG. 21 is a sectional view showing a conventional technique.

FIG. 22 is a sectional view showing a conventional technique.

FIG. 23 is a sectional view showing a conventional technique.

[Explanation of symbols]

 1. Light guide plate 2. Point light source 3. 3. Direction of light flux Reflective member 5. Convex part 10. Viewing direction 20. LCD panel

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G02F 1/1335 530 G02F 1/1335 530 1/1343 1/1343

Claims (12)

[Claims] 1. A light guide plate provided on a front surface of an object to be illuminated and formed with a plurality of convex portions or concave portions for diffusing light on the surface, and a light source disposed on an end face side of the light guide plate. In the lighting device, a viewing direction of the illuminated object;
An illumination device, wherein an incident direction of light incident on the light guide plate from the light source is substantially matched. 2. The lighting device according to claim 1, wherein the light source is disposed on the near side and / or the back side of the light guide plate with respect to the viewing direction of the illuminated body. 3. The lighting device according to claim 1, wherein the light source is a point light source or a rod light source. 4. The lighting device according to claim 1, wherein the convex portion or the concave portion is formed on a surface of the light guide plate different from a surface facing the object to be illuminated. 5. The lighting device according to claim 1, wherein the projection is formed on a surface of the light guide plate facing the illuminated body. 6. The lighting device according to claim 1, wherein a reflection member is disposed on an end face of the light guide plate. 7. A liquid crystal panel, a light guide plate disposed on a front surface of the liquid crystal panel and having a plurality of convex portions or concave portions formed on the surface thereof for diffusing light, and disposed on an end face side of the light guide plate. A liquid crystal device having a light source, wherein a viewing direction of the liquid crystal panel and an incident direction of light incident on the light guide plate from the light source substantially coincide with each other. 8. The light incident direction from the light source to the light guide plate is at least one direction formed on the liquid crystal panel.
The liquid crystal device according to claim 7, wherein the liquid crystal device is substantially parallel to a direction in which the two electrodes extend. 9. The liquid crystal device according to claim 7, wherein a part of the electrodes formed on the liquid crystal panel is formed of a material having a reflection characteristic. 10. The liquid crystal device according to claim 7, wherein a reflection layer formed of a material having a reflection characteristic is disposed on a back side of the liquid crystal panel. 11. The liquid crystal device according to claim 7, wherein the light source is formed on a lateral side of the liquid crystal panel. 12. An electronic apparatus, wherein the liquid crystal device is arranged.