JP3007735B2 - Liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called reflection type liquid crystal display used for office automation (OA) equipment such as a word processor and a personal computer, a viewfinder of a portable video tape recorder, and various monitors for image signals. Related to the device.

[0002]

2. Description of the Related Art While EL (Electro Luminescence), CRT (Cathode Ray Tube; cathode ray tube), LED (Light Emmiting Diode; light emitting diode) and the like are display devices which emit light by themselves, liquid crystals are themselves. This is a display device that does not emit light but receives and displays light. Therefore, a light source is needed to visualize the display so that it can be seen by the human eye. 2. Description of the Related Art Conventionally, many methods have been proposed and put into practical use as a light source device of a direct-view liquid crystal display device. The main items are shown below.

FIG. 8 is a sectional view showing a configuration example of a liquid crystal display device using a light source device of an illumination lamp system. Lamps 11a, 11b
Are arranged on the front side and side of the liquid crystal display device 12. Light from the lamps 11a and 11b passes through the liquid crystal display device 12, is reflected by the reflector 13, and is again projected on the liquid crystal display device 12 to become display light. In the case of this lighting lamp system,
The lamps 11a and 11b as light sources can be installed on the front side of the display surface of the liquid crystal display device 12, and the number of parts is small.
It is a simple and inexpensive liquid crystal display device.

FIG. 9 is a diagram showing an example of the configuration of a liquid crystal display device using a light source of a reflecting mirror system. The reflecting mirror method is a method that is often used because light use efficiency is high and high luminance is obtained. The reflection plate 22 is disposed on the opposite side of the lamp 23 from the liquid crystal display device 24, and efficiently emits the light from the lamp 23 to the front surface (to the liquid crystal display device 24 side). With the reflector 22 alone, there is a problem that the high-luminance portion is biased toward the periphery of the lamp 23 and the brightness tends to be uneven. Therefore, the diffuser 21 is disposed on the front of the lamp 23 and the thickness of the diffuser 21 is changed to make the brightness uniform. Improve sex. Light from the diffusion plate 21 is projected onto the liquid crystal display device 24.

FIG. 10 is a view showing a configuration of a liquid crystal display device using a light source device of a flat lamp system. A fluorescent agent is applied to the inner surfaces of both the front glass plate 35 and the rear glass plate 36 to form the fluorescent screen 31. Discharge electrodes 32a and 32b are provided on both left and right ends of the phosphor screen 31, respectively.
The fluorescent screen 31 emits light due to the discharge between a and 32b. Light from the phosphor screen 31 is projected on the liquid crystal display device 37. The flat lamp system has an advantage that the lamp itself is a flat plate and only needs to be disposed on the back side of the liquid crystal display device 37, and the use efficiency of light is high because an optical system is unnecessary.

Light Guide Plate FIG. 11 is a diagram showing a configuration of a liquid crystal display device using a light source device of a light guide plate system. The light radiated from the lamp 41 is guided by multiple reflections on the inner surface of the light guide plate 43 made of acrylic resin or the like having excellent translucency. Light guide plate 4
A reflector 42 is provided on the surface opposite to the liquid crystal display 45 of FIG. 3, and light from the lamp 41 is extracted only from the front through the diffusion plate 44 and is projected on the liquid crystal display 45. . Here, the lamp 41 is often focused by using a reflector 42 and a slit (not shown) to improve the light use efficiency. However, in principle, this light source device performs total reflection of the light guide plate. Since it is not used, the reflection plate 42 and the slit do not limit the incident angle of light. Since this light source device is relatively thin and has excellent uniformity of luminance, it can cope with thinning of electronic equipment using a portable liquid crystal display device.

EL system EL is a thin, lightweight, planar light source device having excellent brightness uniformity and characteristics as a light source device of a liquid crystal display device. The selection range is narrow,
It has disadvantages such as rapid color degradation during use, and has been replaced with a fluorescent lamp along with the colorization of liquid crystal display devices. However, in recent years, the development of EL with high luminance and long life has been progressing, and the EL lamp has been reviewed again with the reduction in the thickness of the liquid crystal display device.

FIG. 12 is a diagram showing a configuration of a liquid crystal display device using a light source device of a transparent reflector type. The light radiated from the lamp 51 is reflected by a front reflector 54 disposed on the front surface (on the observer 55 side) of the liquid crystal display device 52, passes through the liquid crystal display device 52, and is reflected by a rear reflector plate 53. After passing through the liquid crystal display device 52 again and passing through the front reflector 54, the light reaches the observer 55 looking at the liquid crystal display device 52. A liquid crystal display device using this light source device has not been put to practical use yet.

[0009]

In recent years, OA devices such as word processors and personal computers have been downsized.
It is becoming more portable. For portable equipment, thinning and lightening are indispensable conditions in consideration of easy portability, and keyboards, display devices, batteries and the like are rapidly becoming thinner and lighter. On the other hand, it is also important to reduce power consumption, and reflection-type liquid crystal display devices can be viewed only with external light in a well-lit environment, so display devices without a light source device are widely used. ing. However, in this type of liquid crystal display device, there is a problem that when the surrounding illumination is dark, the display becomes difficult to see, which hinders use.

[0010] In order to solve these problems, lightweight,
There is a need for a reflective liquid crystal display device having a light source device that is thin and can uniformly illuminate the entire display device. In a reflection type liquid crystal display device, since illumination cannot be performed from the back side, a transparent light source device must be disposed in front of the display surface. A reflective liquid crystal display device equipped with a transparent front light source device can display the display only with external light without using the built-in light source device when the surrounding lighting is bright, and the surrounding lighting is not When sufficient, the light source device can be used only when necessary, such as by using a light source device built into the device, so that power consumption can be reduced.

In the case of the above-mentioned six types of prior art, the light source device cannot be installed on the front surface of the liquid crystal display device due to the structure of any of the reflector type, the flat lamp type and the EL type.
In addition, the light guide plate method cannot be installed in front because the light source device has a reflection plate and is not transparent.

In the illumination lamp system and the transparent reflector system, both can be installed in front of the liquid crystal display device.
There is a problem that uniform illumination is difficult. Further, the transparent reflector method has a problem that the light source device is large and thick. In addition, a display mode using a polarizing plate, for example, T
N-LC (Twisted Nematic Liquid Crystal), STN
-In LC (Super Twisted Nematic LC), etc., the liquid crystal molecules in the liquid crystal display element are twisted 90 to 270 degrees as the initial alignment, and the liquid crystal display element is arranged between a pair of polarizing plates, and the optical property of the liquid crystal display element is adjusted. In this case, the display is carried out by using the optical properties in the absence of an electric field and the optical rotation elimination properties when no voltage is applied. Since the light source device must be installed, the light source light passes through each polarizing plate twice, for a total of four times. For this reason, there is a problem that light absorption by the polarizing plate is large, the utilization efficiency of light from the light source is reduced, and the display becomes dark.

An object of the present invention is to provide a reflection type liquid crystal display device capable of bright display.

[0014]

The present invention comprises a transparent substrate,
A liquid crystal display element having a liquid crystal layer interposed between a counter substrate disposed opposite to the transparent substrate, a light guide plate disposed on the transparent substrate side of the liquid crystal display element, and the light guide plate The light source disposed on the side of the light guide plate is disposed on the opposite side of the light guide plate with respect to the liquid crystal display device, and includes reflecting means for reflecting incident light from the liquid crystal display device. A plurality of hemispherical projections are interspersed and formed, and the light propagates through the light guide plate while being totally reflected by the light source on the liquid crystal display element side surface of the light guide plate and the surface opposite to the liquid crystal display element. Illumination light is emitted from the hemispherical projection, and the refractive index of the light guide plate is set to n, the refractive index of a substance located on the opposite side of the light guide plate from the liquid crystal display element is set to n1, and the light guide plate is set to the liquid crystal display element. Is n1 when the incident angle of the light source light on the opposite surface is θ.
A liquid crystal display device characterized by satisfying a condition of <n · sin θ.

[0015]

[0016]

According to the present invention, the reflecting means is disposed on the side of the opposing substrate which is disposed opposite to the transparent substrate, and the transmission / reception of light is performed using a liquid crystal display element which reflects light incident from the side of the transparent substrate.
The display is performed by controlling the cutoff. In the liquid crystal display device of the present invention, the light guide plate is disposed on the transparent substrate side of the liquid crystal display element, and the light source is disposed on the outside of the side surface of the light guide plate.

At this time, the angle of incidence θ of the light source light on the inner surface of the light guide plate on the side opposite to the liquid crystal display element is set so as to satisfy the above relational expression 1, that is, to be totally reflected. Of the reflected light, at least the light incident on the protrusions is smaller than the light incident on the surface other than the protrusions, and thus is emitted toward the liquid crystal display element. In this way, when the illumination light is incident on the liquid crystal display element from the surface of the light guide plate on the liquid crystal display element side, the light can be made closer to the normal direction on the transparent substrate on the light guide plate side of the liquid crystal display element. As a result, the illumination light from the light guide plate can be guided to the liquid crystal display element as much as possible to be incident. Moreover, the reflected light incident on the liquid crystal display element and reflected by the reflection means,
It is difficult for total reflection to occur on the transparent substrate on the light guide plate side of the liquid crystal display element. In this way, more reflected light can be transmitted to the viewer through the transparent substrate on the light guide plate side of the liquid crystal display element.
Furthermore, since the light guide plate has a surface portion on which the projections are not formed, the reflected light from the liquid crystal display element can also be favorably guided to the observer by this. Can be satisfactorily observed by the observer, and there is no possibility that the display is greatly distorted. The light source light is incident on the liquid crystal display element without being emitted to the transparent substrate side, that is, the observer side. This incident light is reflected by the reflection means provided on the counter substrate side, and only the light that does not conform to the state of total reflection by the light guide plate among the display light transmitted through the liquid crystal display element passes through the light guide plate. In other words, light incident on the eyes of an observer located at a certain distance from the transparent substrate serving as the display surface does not normally meet the conditions for total reflection, so that the display can be viewed without any problem. Further, when the light source is turned off, the light guide plate becomes transparent, and the display based on the external light is performed without obstructing the entrance of the external light from the transparent substrate side.

As described above, the light source device including the light guide plate and the light source can be installed on the front side (display surface) side of the liquid crystal display element. The light plate becomes transparent, does not hinder the incidence of external light, and can achieve good display.
Further, the light guide plate is formed by being scattered on the surface of the liquid crystal display element side.
The shape of the multiple projections
Therefore, the processing can be easily performed .

[0019]

FIG. 1 is a sectional view showing the structure of a liquid crystal display device 60 according to an embodiment of the present invention. Liquid crystal display device 60
Is a liquid crystal display element 72 between a pair of polarizing plates 64a and 64b.
Are arranged. The liquid crystal display element 72 includes a liquid crystal layer 6 between a pair of transparent substrates 65a and 65b made of glass or the like.
6 interposed. In this embodiment, the liquid crystal display element 72 includes a TFT (Thin Film Transistor) as described later.
This is a liquid crystal display element of the r) type. In this embodiment, the TFT
The method will be described as an example, but the present invention is not limited to this, and other methods, for example, MIM (Metal Insulator Met)
al) or a simple matrix method.

A reflection plate 68 is disposed on the side of the polarization plate 64b opposite to the liquid crystal display element 72. The surface of the reflection plate 68 on the liquid crystal display element 72 side is formed with irregularities in order to uniformly reflect incident light from the liquid crystal display element 72 side.

The light guide plate 61 is disposed between the liquid crystal display element 72 and the polarizing plate 64a with air layers 71a and 71b interposed between the polarizing plate 64a. A plurality of protrusions are formed on the surface of the light guide plate 61 on the liquid crystal display element 72 side. What
In the present invention, the plurality of protrusions are formed into hemispheres which are easy to process.
This hemispherical projection will be expanded later.
This will be described in detail with reference to a large drawing and the like.

On the outer side of the opposing side surface of the light guide plate 61,
Lamps 63a and 63b are arranged respectively. Light guide plate 6
Collimators 62a and 62b are respectively arranged between 1 and the lamps 63a and 63b. Collimators 62a, 6
2b limits the incident angle of the light emitted from the lamps 63a and 63b to the upper surface 61a of the light guide plate 61. Note that a reflector may be provided on the side of the light guide plate 61 where the lamps 63a and 63b are not arranged to prevent light leakage.

The transparent substrate 65b and the polarizing plate 64b, and the polarizing plate 64b and the reflecting plate 68
a, 67b.

Here, the transparent substrate 65a and the liquid crystal layer 66
, A transparent substrate 65b, a polarizing plate 64b, and a transparent adhesive 6
Materials were selected so that the refractive indices of 7a and 67b were almost equal.

Here, the collimator 6 is used to limit the incident angle of the incident light from the lamps 63a and 63b to the light guide plate 61.
Although 2a and 62b are used, other methods may be used as long as the incident angle can be limited within a certain range. For example,
It is also possible to limit the incident light by attaching slits to the lamps 63a and 63b.
In the portions close to 3a and 63b, since the angle of incidence on the light guide plate 61 is small and total reflection does not occur, the light source light leaks directly from the surface of the light guide plate 61, so that this portion may be shielded. When the refractive index n of the light guide plate 61 is set to an appropriate value, all the light incident on the light guide plate 61 can satisfy the condition of total reflection. In this case, the collimator may be omitted.

If necessary, the surface 61 of the light guide plate 61
a, 61b, an anti-reflection film,
A coating for facilitating total reflection or a coating for preventing a scratch or the like or for repairing a generated scratch may be provided.

If the reflection plate 68 and the transparent substrate 65b can be fixed by means other than the transparent adhesive, a filler such as silicone oil may be filled instead of the transparent adhesive.

Further, the upper surface 61a of the light guide plate 61
May be coated with a material having a lower refractive index than the light guide plate material. In this case, the polarizing plate 64a can be directly bonded on the light guide plate 61. Further, by setting the refractive indexes of the light guide plate 61 and the polarizing plate 64a to appropriate values, the polarizing plate 64a can be directly adhered onto the light guide plate 61. The lower surface 61b of the light guide plate 61
May be coated with a material having a higher refractive index than the light guide plate 61. If there is no problem in extracting light from the lower surface 61b of the light guide plate 61, the lower surface 61b may be coated, or may be bonded to the glass substrate 65a with a transparent adhesive having an appropriate refractive index. I don't care.

In this embodiment, a liquid crystal display device using a polarizing plate has been described. However, the present invention can be applied to a liquid crystal display device using no polarizing plate, such as a polymer dispersion type. In this case, the polarizing plates 64a and 64b and the adhesive 67a can be omitted in FIG.

FIG. 2 is a process chart for explaining a manufacturing process of the liquid crystal display device 60. In step a1, a transparent substrate 65b is formed using borosilicate glass.
On one surface of amorphous silicon TF
T is formed to form pixel electrodes in a matrix. A resin such as polyimide is applied to the surface, and a rubbing process is performed to form an alignment film. In step a2, a transparent substrate 65a is formed using borosilicate glass or the like, and a transparent electrode (ITO: Indium Tin Oxide) as a common electrode and an alignment film are formed on one surface thereof.

In step a3, the transparent substrates 65a and 65b are arranged so that the electrode forming surfaces face each other, and are bonded together with a spacer interposed between the substrates. In step a4, the transparent substrate 6
A TN (twisted nematic) liquid crystal is sealed between 5a and 65b. Here, the liquid crystal is ZLI- manufactured by Merck.
Although 1565 was used, another liquid crystal material may be used. For example, when a polymer-dispersed liquid crystal, which is a liquid crystal material in which an organic polymer and a liquid crystal compound are compounded, is used, the polarizing plate becomes defective, so that light use efficiency is improved. When a guest-host type liquid crystal material is used, the polarizing plate becomes 1
It can be displayed in sheets. Further, when a white-tailored liquid crystal material is used among the guest-host type liquid crystal materials, a polarizing plate becomes unnecessary as in the case of a liquid crystal material in which an organic polymer and a liquid crystal compound are combined. On the other hand, many TN liquid crystal materials are known in addition to the materials shown in this embodiment, and other materials may be used.

Thereafter, in step a5, the polarizing plate 64b is bonded to the transparent substrate 65b with an epoxy-based transparent adhesive 67a. Subsequently, in step a6, an Al reflecting plate 68 on which a hairline process has been performed is bonded to the polarizing plate 64b with an epoxy-based transparent adhesive 67b. Thereafter, PMMA having a thickness of about 2.5mm was formed projections of semispherical on one surface (polymethyl
A light guide plate 61 made of metacrylate) was fixed at a position where the light guide plate 61 was lightly in contact with the upper substrate 65a.

In this embodiment, the Al reflecting plate 68 is connected to the polarizing plate 64.
Although an example of bonding to b is shown, the present invention is not limited to this. For example, ECB (Electrically controlled birefri
ngence) type LC, guest host type LC, white tailor type guest host LC, polymer dispersion type LC or the like, the polarizing plate 64b can be omitted from the pair of polarizing plates 64a, 64b, so that the reflecting plate is provided on the glass substrate 65b. Can be formed.

Subsequently, in step a8, a polarizing plate 64a was attached at an interval of about 1 mm from the upper surface 61a of the light guide plate 61. After fixing them to a frame (not shown),
9, the collimators 62a and 62b and the lamp 63
a, 63b.

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

FIG . 4 illustrates the principle of operation of the light guide plate 61.
FIG. In the present invention, the light guide plate 61 is easily processed.
A plurality of hemispherical projections 81c are formed.

The upper surface 61 of the light guide plate of the illumination light 89a, 89b incident on the light guide plate 61 from the lamps 63a, 63b.
a and the incident angle with respect to the lower surface 61b are θ1
5, θ11, and the refractive index of the light guide plate 61 is n.

[0051]

## EQU11 ## sin θ11> 1 / n

[0052]

When the condition of sin θ15> 1 / n is satisfied, the illumination lights 89a and 89b are
1 propagates inside the light guide plate 61 while repeating reflection between the upper surface 61a and the lower surface 61b.

When the illumination light 89a, 89b is incident on the projection 81c formed on the lower surface 61b of the light guide plate 61,
The illumination light 89a passing through the right end proximity portion 81e of the projection 81c in FIG. 4 and the left end proximity portion 81 of the projection 81c
Surface 81d of projection 81c of illumination light 89b passing through f
Incident angles θ13 and θ16 at

[0054]

(13) θ13 ≒ 90 ° −θ15

[0055]

Equation 14: θ16θ90 ° −θ11

The illumination light 89a, 8 incident on the projection 81c
Since 9b passes between the right end proximity portion 81e and the left end proximity portion 81f, the angle of incidence on the surface 81d of the projection 81c is smaller than the angles θ13 and θ16. When PMMA is used as the material of the light guide plate, the refractive index is about 1.5. Therefore, when the angle of incidence on the surface of the light guide plate is 48 ° or more, the illumination light is emitted from the projection 81c. As a result of restricting the incident angle of the light guide plate 61 to be equal to or more than 48 ° by a collimator,
No leakage of illumination light from the light guide plate surface was observed, and the illumination light was emitted from the lower surface 61b. When the light guide plate 61 was attached to the liquid crystal display element 72, good display quality was obtained.

FIG. 5 is a diagram for explaining another embodiment of the present invention. Referring to FIG. 5, first, from Snell's law,

[0058]

The following holds: n · sin θb = sin θa Here, when light from the external lamps 63 a and 63 b enters the light guide plate 61,

[0059]

## EQU16 ## sin θb <1 / n. On the other hand, the condition that the incident light is totally reflected on the surface inside the light guide plate 61 is as follows.

[0060]

## EQU17 ## sin θc> 1 / n. here,

[0061]

Since θb + θc = 90 °, from the above equations (16) and (17),

[0062]

(19) sin θb <1 / n <sin (90 ° −θb) Θb satisfying the relational expression of Expression 19 is

[0063]

## EQU20 ## θb <45 °. At this time, the refractive index n is

[0064]

## EQU21 ## where n> 1.42. Therefore, the refractive index n of the light guide plate 61 becomes
When the above condition is satisfied, the collimators 62a and 62b for limiting the incident angle of the incident light on the light guide plate 61 become unnecessary. For example, when PMMA is used as the material of the light guide plate 61, the refractive index n is 1.5, so that a collimator for limiting the upper limit of the incident angle of the incident light from the lamps 63a and 63b becomes unnecessary.

FIG. 6 is a diagram for explaining another operation principle of the light guide plate 61. Here, the refractive index of the light guide plate 61 is n
The refractive index of a substance located on the side of the light guide plate 61 opposite to the liquid crystal display element 72 is defined as n1, and the refractive index of a substance located on the liquid crystal display element 72 side of the light guide plate 61 is defined as n2.

FIG. 6A shows the operation when n1 = n2. Although the light is reflected on the lower surface 61b of the light guide plate 61 other than the protrusion 61c, the light incident on the protrusion 61c is emitted to the liquid crystal display element 72 side without being reflected.

FIG. 6B shows the operation principle when n1> n2. Although the light is totally reflected on the upper surface 61a of the light guide plate 61, it is also emitted toward the liquid crystal display element 72 from portions other than the protrusions 61c of the lower surface 61b. Projection 61c
All light incident on the liquid crystal display element 72 is emitted to the liquid crystal display element 72 side as in the case shown in FIG.

FIG. 6C shows the principle of operation when the refractive index n2 is sufficiently smaller than the refractive index n of the light guide plate 61. In this case, the light emitted from the protrusion 61c is
Again. At this time, the re-incident light is upward from the upper surface 61a of the light guide plate 61, that is,
The light is emitted to the 0 side. Although such upward emission of light is not very desirable, it does not cause a major problem unless it reaches the eyes of the observer 70 directly. As described above, the protrusions 61c are formed to be scattered on the surface 61b. Therefore, when the illuminating light propagating in the light guide plate 61 is incident on the transparent substrate 65a of the liquid crystal display element 72 via the protrusion 61c, the light can be made closer to the normal direction on the transparent substrate 65a. As a result, as much light as possible can be guided to the liquid crystal display element 72, and the reflected light incident on the liquid crystal display element and reflected by the reflection plate 68 becomes
The total reflection is less likely to occur on the transparent substrate 65 a of the liquid crystal display element 72, and more reflected light can be guided to the observer 70. As described above, the path of light that is preferably incident on the liquid crystal display element 72 from the protrusion 61c is as shown in FIG.
6 to (3) are indicated by reference numerals 73 to 75, respectively. Further, the projections 61c of the light guide plate 61 are formed in a dotted manner, and the remaining surface of the surface 61b where the projections 61c are not formed is flat, so that the display of the liquid crystal display element 72 is good for the observer 70. And the display is not greatly distorted.

FIG. 7 is a graph showing the relationship between the number of protrusions and the amount of light. The number of protrusions may be appropriately selected according to the light amounts of the lamps 63a and 63b. In addition, by appropriately changing the size, shape, density, and the like of the protrusions within the surface of the light guide plate, the amount of light extracted from the light guide plate can be made uniform. On the other hand, the projections are located at locations other than the pixels of the liquid crystal display element 72,
For example, when the light guide plate is disposed on the light guide plate so as to be on a light-shielding film between the pixels, the display is not affected at all by the projections, and a more desirable display can be obtained.

In this embodiment, PMMA is used as the material of the light guide plate.
Was used, but other materials such as glass, CR-39 resin, polycarbonate, polyvinyl chloride, and polyester may be used as long as light can be uniformly guided without attenuation and the refractive index is an appropriate value. .

As described above, the light emitted from the light guide plate 61 is not reflected by the transparent substrate 65a but proceeds straight until it reaches the reflection plate 68. The light that has reached the reflecting surface 68a of the reflecting plate 68 is irregularly reflected by the reflecting surface 68a, and after being uniformized, the adhesive 67b, the polarizing plate 64b, the adhesive 67a, and the transparent substrate 65 are formed.
b, the liquid crystal layer 66, the transparent substrate 65a, the air layer 71b, the light guide plate 61, the air layer 71a, and the polarizing plate 64a, and sequentially reach the eyes of an observer 70 looking at the display surface. At this time, a diffusion plate may be provided between the reflection plate 68 and the transparent substrate 65b in order to improve the uniformity of light.

As described above, according to the present embodiment, the light guide plate 61, the collimators 62a and 62b, and the lamps 63a and 63b constituting the light source device can be arranged on the front surface (on the observer 70 side) of the liquid crystal display element 72. it can. by this,
Even when the surroundings are dark in the reflective liquid crystal display device, the light required for display is given to the liquid crystal display element 72 by operating (lighting) the light source device, and the display can be easily viewed.

Further, when the surroundings are bright, the light guide plate 61 is made transparent by turning off the light source device, so that a display that is sufficiently visible with only external light can be realized. By operating the light source device only when necessary, power consumption can be reduced.

[0074]

In the present embodiment, the lamps 63 that are arranged opposite to each other
Although a and 63b are used, one lamp may be used as long as a sufficient amount of light can be obtained.

Furthermore, compared to the conventional illumination lamp system, a display with excellent uniformity can be obtained. Furthermore, a thin, lightweight, bright, and highly uniform display can be obtained as compared with the conventional transparent reflection type.

[0077]

As described above, according to the present invention, the light guide plate and the light source constituting the light source device can be installed on the front surface of the liquid crystal display device, so that the light from the light source directly enters the eyes of the observer. However, it is possible to uniformly illuminate the liquid crystal display element. This makes it possible to illuminate the reflection-type liquid crystal display device, which was difficult to illuminate conventionally. The use of a light guide plate is suitable for a portable OA device equipped with a reflective liquid crystal display device. In addition, the light source can be turned off when the surrounding area is bright and can be illuminated with external light, and turned on when the surrounding area is dark. it can. in this way,
A light-weight, thin, low-power-consumption reflective liquid crystal display device can be realized. In particular, according to the present invention, when the illumination light is emitted from the projection and the light is incident on the liquid crystal display element from the projection by the function of the projection, the light is transmitted to the transparent substrate on the light guide plate side of the liquid crystal display element. , It becomes possible to approach the normal direction. This makes it difficult for reflected light incident on the liquid crystal display element and reflected by the reflection means to be totally reflected on the transparent substrate on the light guide plate side of the liquid crystal display element. This allows more reflected light to be guided from the liquid crystal display element to the observer via the light guide plate. Further, according to the present invention, the remaining surface of the surface on the liquid crystal display element side where no projection is formed is flat. Therefore, the light emitted from the liquid crystal display element is guided to the observer not only through the protrusion but also through the flat surface portion. Therefore, an observer can observe the display of the liquid crystal display element well. A dot is formed on the surface of the light guide plate on the liquid crystal display element side.
The shape of the plurality of protrusions that are formed
Thereby, the processing can be easily performed .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a liquid crystal display device 60 according to an embodiment of the present invention.

FIG. 2 is a process diagram illustrating a method for manufacturing the liquid crystal display device 60.

FIG. 3 shows another light guide plate 61 provided in the liquid crystal display device 60 .
FIG. 3 is a diagram for explaining the operation principle of FIG.

FIG. 4 is a diagram for explaining another embodiment of the present invention.
You.

FIG. 5 shows still another operation of the light guide plate 61 used in the present invention .
It is a figure for explaining an operation principle.

FIG. 6 is a graph showing the relationship between the number of protrusions and the amount of light.
You.

FIG. 7 illustrates a configuration example of a liquid crystal display device using an illumination lamp method .
FIG.

FIG. 8 shows a configuration example of a liquid crystal display device using a reflecting mirror system .
It is sectional drawing.

FIG. 9 is a configuration example of a liquid crystal display device using a flat lamp system .
FIG.

FIG. 10 shows a configuration example of a liquid crystal display device using a light guide plate method .
FIG.

FIG. 11 is a configuration example of a liquid crystal display device using a transparent reflection plate method .
FIG.

[Explanation of symbols]

Reference Signs List 60 liquid crystal display device 61 light guide plate 61a upper surface 61b lower surface 61c, 81c protrusion 62a, 62b collimator 63a, 63b lamp 64a, 64b polarizing plate 65a, 65b transparent substrate 66 liquid crystal layer 67a, 67b transparent adhesive 68 reflecting plate 89a, 89b light source light 70 observer 71a, 71b air layer 72 liquid crystal display element 68a reflection surface

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-189679 (JP, A) JP-A-57-146286 (JP, A) JP-A-59-99479 (JP, A) 4515 (JP, U) Fully open 1986-36911 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1335 520 G02F 1/1335 530

Claims (1)

(57) [Claims] 1. A liquid crystal display element having a liquid crystal layer interposed between a transparent substrate and an opposing substrate disposed opposite to the transparent substrate, and disposed on the transparent substrate side of the liquid crystal display element. A light guide plate to be provided, a light source disposed on a side of the light guide plate, and a reflection unit disposed on a side opposite to the light guide plate with respect to the liquid crystal display element and reflecting incident light from the liquid crystal display element, A plurality of hemispherical projections are formed on the surface of the light guide plate on the side of the liquid crystal display element, and a plurality of hemispherical projections are formed on the surface of the light guide plate on the side of the liquid crystal display element from the light source. Illumination light that propagates inside the light guide plate while being reflected is emitted from the hemispherical projection, and the refractive index of the light guide plate is n, and the refractive index of a substance located on the opposite side of the light guide plate from the liquid crystal display element is n1. And the incident angle of the light source light on the surface of the light guide plate opposite to the liquid crystal display element is θ. Time, the liquid crystal display device, wherein a satisfies the condition n1 <n · sinθ.