JP2001134207A - Electro-optic device and electronic appliance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electro-optic device which can obtain bright display with a low electric power and to provide an electronic appliance equipped with that electro-optic device. SOLUTION: The device is equipped with display substrates 1, 2 having a display screen, a light source 31, and a light guide plate 32 which is disposed on the back side of the display screen of the display substrates 1, 2 and which accepts the light emitted from the light source 31 on its end face and allows the light to exit through the exit face 32a facing the display substrates 1, 2 to the back face of the display substrate. The thickness of the light guide plate 32 is almost uniform all over the body, and the light guide plate 32 is disposed as tilted from the display substrates 1, 2, in such a manner that the exit face 32 comes nearer to the back face of the display screen of the substrates 1, 2 with the distance from the light source 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electro-optical device provided with a light guide plate disposed behind a display surface of a display substrate and emitting light emitted from a light source toward the back surface of the display substrate. The present invention relates to an electronic device including an electro-optical device.

[0002]

2. Description of the Related Art A pair of substrates arranged with a liquid crystal interposed therebetween;
2. Description of the Related Art A liquid crystal device including a backlight device disposed behind a pair of substrates is known. The backlight device is
A light source such as an LED (light emitting diode) is provided, and a light guide plate that guides light emitted from the light source and emits the light toward the back side of the pair of substrates. When a plate-shaped light guide plate having a uniform thickness is used, the light guide plate is arranged in parallel with the pair of substrates, and the light emitted from the light source is received on the end face of the light guide plate, and the light guide plate facing the pair of substrates is received. Light is emitted from the emission surface of the light plate to the back side of the pair of substrates.

[0003] With such a backlight device, substantially uniform light can be applied to the entire pair of substrates.

[0004]

However, in the above-described liquid crystal device, it is necessary to enable bright display with low power, and further improvement in this respect is desired.

[0005] It is an object of the present invention to provide an electro-optical device capable of obtaining a bright display with low power, and an electronic apparatus provided with such an electro-optical device.

[0006]

To achieve the above object, an electro-optical device according to the present invention includes a display substrate having a display surface, a light source, and a rear surface of the display surface of the display substrate. A light guide plate that receives the light emitted from the light source at an end face, and emits the light toward the back surface of the display substrate via an emission surface facing the display substrate, and the light guide plate has a thickness of The light guide plate is arranged so as to be substantially uniform throughout, and is inclined with respect to the display substrate such that the emission surface approaches the rear surface of the display surface of the display substrate as the distance from the light source increases. It is characterized by the following.

According to this electro-optical device, the light guide plate is inclined with respect to the display substrate such that the emission surface approaches the back surface of the display surface of the display substrate as the distance from the light source increases. Is efficiently radiated to the display substrate, so that a bright display can be realized with low power.

[0008] The light guide plate may be 0.2 to 2 degrees, more preferably 0.1 to 2 degrees with respect to the display substrate, so that the emission surface approaches the back surface of the display surface of the display substrate as the light guide plate moves away from the light source. It may be arranged at an angle of 5 to 1 degree.

In this case, since the light guide plate is arranged at an angle of 0.2 to 2 degrees, more preferably 0.5 to 1 degree with respect to the display substrate, the light from the light source is more efficiently emitted. Thus, a bright display can be realized with low power by irradiating the display substrate.

[0010] The light guide plate may be made of an acrylic resin.

[0011] The display substrate may include a pair of substrates arranged with a liquid crystal interposed therebetween.

According to another aspect of the present invention, there is provided an electronic apparatus including an electro-optical device, wherein the electro-optical device includes a display substrate having a display surface, a light source, and the display surface of the display substrate. A light guide plate that is disposed on the back side of the light guide, receives light emitted from the light source at an end face, and emits the light toward the back surface of the display substrate via an emission surface facing the display substrate. The light guide plate has a substantially uniform thickness throughout, and the light guide plate is attached to the display substrate such that the emission surface approaches the back surface of the display surface of the display substrate as the light guide plate moves away from the light source. It is characterized by being arranged to be inclined with respect to.

[0013] According to this electro-optical device, the light guide plate is inclined with respect to the display substrate so that the exit surface approaches the back surface of the display surface of the display substrate as the distance from the light source increases. Is efficiently radiated to the display substrate, so that a bright display can be realized with low power.

[0014] The light guide plate may be 0.2 to 2 degrees with respect to the display substrate, and more preferably 0.2 to 2 degrees with respect to the display substrate, such that the emission surface approaches the back surface of the display surface of the display substrate as the distance from the light source increases. It may be arranged at an angle of 5 to 1 degree.

In this case, the light guide plate is disposed at an angle of 0.2 to 2 degrees, more preferably 0.5 to 1 degree with respect to the display substrate, so that the light from the light source is more efficiently emitted. Thus, a bright display can be realized with low power by irradiating the display substrate.

To facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiment.

[0017]

(Embodiment of electro-optical device) FIG. 1
Is a longitudinal sectional view of a liquid crystal panel constituting a simple matrix type liquid crystal display device as an example of the electro-optical device of the present invention, FIG. 2 is a diagram showing an arrangement relationship between a transparent substrate, a light guide plate and a printed circuit board, and FIG. It is a figure which shows the attachment state between a unit and a light guide plate.

In this liquid crystal panel P, a liquid crystal layer 3 is sealed by a frame-like sealing material 4 between two transparent substrates 1 and 2 arranged in parallel to each other to form a liquid crystal cell. The liquid crystal layer 3 is composed of a nematic liquid crystal having a twist angle of 240 degrees. In FIG. 1, a color filter 5 in which three colored layers of R (red), G (green), and B (blue) are arranged in a predetermined pattern is formed on the inner surface of the upper transparent substrate 1. A transparent protective film 7 is coated on the surface of the color filter 5, and a plurality of stripe-shaped transparent electrodes 8 are formed on the surface of the protective film 7 by ITO or the like. An alignment film 9 is formed on the surface of the transparent electrode 8, and the alignment film 9 is rubbed in a predetermined direction.

In FIG. 1, a transflective film 1 made of a thin Al film having a thickness of 30 nm is formed on the inner surface of a transparent substrate 2 on the lower side.
1. an insulating layer 12 made of SiO ₂ or acrylic resin,
A transparent electrode 14 made of ITO and an alignment film 15 are sequentially formed. In the present embodiment, the transparent electrode 14 is formed, but the transflective film 11 made of the thin film Al may be used as the pixel electrode. In this case, the insulating layer 12 and the transparent electrode 14 become unnecessary. In addition, as the transflective film 11,
For example, an aluminum film or the like in which a slit or the like is formed and has a predetermined aperture ratio can be used.

On the outer surface of the upper transparent substrate 1, a polarizing plate 1
7, and a retardation plate 18 is disposed between the polarizing plate 17 and the transparent substrate 1. On the lower side of the liquid crystal cell,
A retardation plate 19 is arranged behind the transparent substrate 2, and a polarizing plate 20 is arranged behind the retardation plate 19. In addition,
The retardation plate 19 is made of a stretched film made of a material such as polycarbonate which is likely to exhibit birefringence, and plays a role of color compensation.

As shown in FIG. 2, a liquid crystal driving IC 2 for driving a liquid crystal cell is provided in a region where the transparent substrate 1 extends outside the transparent substrate 2 (a region on the right end side in FIG. 2).
1 is implemented. Thus, the liquid crystal panel P is configured as a so-called COG (Chip on glass) type liquid crystal panel.

In this liquid crystal display device, an image displayed on the liquid crystal panel P is visually recognized from the side of the transparent substrate 1 (the upper side in FIGS. 1 and 2). Each element formed on the transparent substrates 1 and 2 constitutes a display substrate.

As shown in FIGS. 1 to 3, a plurality of LED (light emitting diode) elements 31a emitting white light and an LED unit 31 made of a transparent resin for molding the LED element 31a are provided below the polarizing plate 20. And a light guide plate 32 adhered to the LED unit 31 via the end face. On the front side (the upper side in FIG. 1) of the LED unit 31, a reflector 33 for reflecting light emitted from the LED element 31a is attached. As shown in FIG. 2, the LED unit 31 is
5 is implemented.

The light guide plate 32 is a transparent body made of acrylic resin or the like, and has an emission surface 32 facing the transparent substrate 2.
In a, a rough surface for scattering light is formed, or a printing layer for scattering light is formed. Light guide plate 3
Reference numeral 2 denotes an end face that receives light emitted from the LED unit 31 as a light source, and transmits the transparent substrate 2 through an emission surface 32a.
The light of almost uniform intensity is emitted to the side of. In addition, a reflection sheet is provided below the surface 32b facing the emission surface. Various optical sheets such as a prism sheet and a diffusion sheet may be provided on the exit surface 32a.

As shown in FIGS. 1 and 2, the light guide plate 32
Has a substantially uniform thickness throughout. The light guide plate 32 is arranged such that the emission surface 32a approaches the transparent substrate 2 as the distance from the LED unit 31 as a light source increases.
It is arranged at an angle of 0.2 to 2 degrees, more preferably at an angle of 0.5 to 1 degrees with respect to the transparent substrate 1 or the transparent substrate 2. 1 and 2 schematically illustrate the liquid crystal display device, and the angle of the light guide plate 32 is not accurate.

In this embodiment, the light guide plate 32 is a transparent substrate 1
Or because it is provided at an angle to the transparent substrate 2,
The intensity of light emitted toward the front side of the liquid crystal panel via the emission surface 32a can be increased. Therefore, when performing transmissive display, a bright display with low power can be obtained.

Hereinafter, the reflection type display will be described. External light passes through the polarizing plate 17, the phase difference plate 18, and the transparent substrate 1 shown in FIG. 1, respectively, and after passing through the color filter 5, the liquid crystal layer 3, the alignment film 15, the transparent electrode 14, and the insulating layer 12, is semi-transmissively reflected. Part of the light is reflected by the film 11, passes through the color filter 5 again, and is emitted from the polarizing plate 17. At this time, a voltage is applied to the liquid crystal layer 3 by the transparent electrode 8 and the transparent electrode 14. With this applied voltage, the bright state, dark state,
And the intermediate brightness can be controlled.

Next, the transmission type display will be described. The light emitted from the emission surface 32a of the light guide plate 32 is
The light is converted into a predetermined elliptically polarized light by the phase difference plate 19, and a part of the elliptically polarized light is transmitted through the transflective film 11. The transmitted light is
It is introduced into the liquid crystal layer 3 through the insulating layer 12, the transparent electrode 14, and the color filter 15. Here, the light introduced into the liquid crystal layer 3 passes through the color filter 5 and then passes through the phase difference plate 18.
Pass through. At this time, depending on the voltage applied to the liquid crystal layer 3, a state in which light passes through the polarizing plate 17 (bright state), a state in which light is absorbed (dark state), and an intermediate state can be controlled. .

(Embodiment of Electronic Apparatus) FIG. 4 shows a portable telephone which is an embodiment of the electronic apparatus of the present invention.
The mobile phone 100 shown here includes an antenna 101, a speaker 102, a liquid crystal device 1 (FIG. 1 and the like), a key switch 10
3. Various components such as the microphone 104 are stored in an outer case 106 serving as a housing. Further, inside the outer case 106, a control circuit board 107 on which a control circuit for controlling the operation of each of the above-mentioned components is mounted is provided.

In the portable telephone 100, a signal input through the key switch 103 and the microphone 104, data received by the antenna 101, and the like are input to the control circuit of the control circuit board 107. Then, the control circuit displays images such as numbers, characters, and patterns on the display surface of the liquid crystal device 1 based on the input various data, and transmits transmission data from the antenna 101.

As described above, the present invention has been described with reference to the preferred embodiments. However, the present invention is not limited to the embodiments, and can be variously modified within the scope of the invention described in the claims. For example, in the present embodiment, an example of application to a simple matrix type transflective liquid crystal display device is shown, but the present invention is applicable not only to other liquid crystal devices but also to electro-optical devices other than liquid crystal devices. . Also, for example, in the embodiment of the electronic device, the case where the liquid crystal device of the present invention is used for a mobile phone as the electronic device is exemplified. , An electronic organizer, a finder of a video camera, and the like.

[0032]

According to the electro-optical device and the electronic apparatus of the present invention, the light guide plate is arranged obliquely with respect to the display substrate so that the emission surface approaches the back surface of the display surface of the display substrate as the distance from the light source increases. Therefore, light from the light source is efficiently radiated to the display substrate, and thus a bright display with low power can be realized.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a liquid crystal panel included in a simple matrix type liquid crystal display device as an example of the electro-optical device of the present invention.

FIG. 2 is a diagram showing an arrangement relationship between a liquid crystal panel, a light guide plate, and a substrate.

FIG. 3 is a diagram showing an attachment state between an LED unit and a light guide plate.

FIG. 4 is an exemplary perspective view showing an embodiment of an electronic device of the invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Transparent substrate 31 LED unit 32 Light guide plate 32a Emission surface

Continued on the front page F term (reference) 2H091 FA02Y FA08X FA08Z FA11X FA11Z FA23Z FA41Z FB02 FD01 LA30 MA10 5G435 AA00 BB12 BB15 BB16 CC12 DD09 DD13 EE27 EE33 EE37 FF01 FF03 FF05 FF06 FF08 HGG GG12 GG03 GG12 H

Claims (7)

[Claims] 1. A display substrate having a display surface, a light source, and a light source disposed on a back surface side of the display surface of the display substrate, receiving light emitted from the light source at an end face, and receiving the light from the display substrate. A light guide plate for emitting light toward the back surface of the display substrate via an emission surface facing the light guide plate, and the thickness of the light guide plate is made substantially uniform throughout, and the light guide plate becomes more distant from the light source. An electro-optical device, wherein the emission surface is inclined with respect to the display substrate such that the emission surface approaches a back surface of the display surface of the display substrate. 2. The light guide plate is inclined at an angle of 0.2 to 2 degrees with respect to the display substrate such that the emission surface approaches a back surface of the display surface of the display substrate as the distance from the light source increases. The electro-optical device according to claim 1, wherein the electro-optical device is arranged at a right angle. 3. The light guide plate is inclined at an angle of 0.5 to 1 degree with respect to the display substrate such that the emission surface approaches the back surface of the display surface of the display substrate as the light guide plate moves away from the light source. The electro-optical device according to claim 1, wherein the electro-optical device is arranged at a right angle. 4. The electro-optical device according to claim 1, wherein the light guide plate is made of an acrylic resin. 5. The electro-optical device according to claim 1, wherein the display substrate includes a pair of substrates disposed with a liquid crystal interposed therebetween. 6. An electronic apparatus comprising an electro-optical device, wherein the electro-optical device is disposed on a display substrate having a display surface, a light source, and a rear surface of the display surface of the display substrate, and emits light from the light source. A light guide plate that receives the generated light at the end face, and emits the light toward the back surface of the display substrate via an emission surface facing the display substrate, wherein the thickness of the light guide plate is substantially uniform throughout. And the light guide plate is arranged to be inclined with respect to the display substrate so that the emission surface approaches the back surface of the display surface of the display substrate as the distance from the light source increases. Electronic equipment. 7. The light guide plate is tilted at an angle of 0.2 to 2 degrees with respect to the display substrate such that the emission surface approaches the back surface of the display surface of the display substrate as the distance from the light source increases. The electronic device according to claim 6, wherein the electronic device is arranged so as to be located at a right angle.