JP2995044B2 - 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 in 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 EL (Electro Lumines)
cence; electroluminescence) or CRT (C
Anode Ray Tube (Cathode Ray Tube), LED
(Light Emitting Diode) is a display device that emits light by itself, whereas a liquid crystal does not emit light by itself, but is a display device that receives and displays light. Therefore, a light source is needed to visualize the display so that it can be seen by the human eye. Conventionally, many methods have been proposed and put into practical use as a light source device of a direct-view type 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 reflection plate 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 diagram 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. This flat-type lamp system has an advantage that the lamp itself has a flat shape 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. Light emitted 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 the 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 often condenses light by using a reflecting plate 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 luminance uniformity, the light source device can cope with a thin electronic device using a portable liquid crystal display device.

EL Method EL is a thin, lightweight, flat type light source device having excellent luminance uniformity and characteristics as a light source device of a liquid crystal display device. 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 thinning 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 equipment such as word processors and personal computers have been reduced in size.
It is becoming more portable. For portable equipment, thinning and lightening are indispensable conditions in consideration of easy portability, and thinning and lightening of keyboards, display devices, batteries and the like are rapidly progressing. 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, this type of liquid crystal display device has 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 view 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 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 reflecting mirror system, the flat lamp system, and the EL system.
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)
id Crystal), STN-LC (Super
In Twisted Nematic LC) or the like, a liquid crystal molecule in a liquid crystal display element is set to 90 degrees to 27 degrees as an initial alignment.
A liquid crystal display element is arranged between a pair of polarizing plates twisted by 0 degrees, and display is performed by using the optical properties of the liquid crystal display element, that is, the optical rotation characteristics when there is no electric field and the optical rotation canceling characteristics when voltage is applied. The lighting lamp method described above,
In the case of the transparent reflection plate method, since the light source device must be installed outside the two polarizing plates, 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 which is disposed opposite to the transparent substrate and has a liquid crystal layer interposed between the substrate and a counter substrate provided with a reflection means for reflecting incident light from the transparent substrate side; A light guide plate disposed on the transparent substrate side, including a light source disposed on a side surface of the light guide plate, a liquid crystal display element side surface of the light guide plate, at least other than a pixel portion formed in the liquid crystal display element A plurality of projections are formed to correspond to the regions, the refractive index of the light guide plate is n, 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 liquid crystal display element of the light guide plate is A liquid crystal display device that satisfies a condition of n1 <n · sin θ when an incident angle of the light source light to the surface on the opposite side is θ.

Hereinafter, the operation of the present invention will be briefly described.

According to the present invention, the reflection means is disposed on the side of the opposing substrate which is disposed opposite to the transparent substrate, and transmits / blocks light using a liquid crystal display element which reflects light incident from the side of the transparent substrate. The display is performed by controlling. 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 outer side of the side surface of the light guide plate.

At this time, the incident angle θ of the light source light to 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 relational expression of the above formula, 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.

This makes it possible to guide as much of the illumination light from the light guide plate as possible to the liquid crystal display device and make it incident. In addition, the reflected light that is incident on the liquid crystal display element and reflected by the reflection means is hardly totally reflected by 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.

Further, since the light guide plate has a plurality of protrusions formed so as to correspond to regions other than the pixel portion, there is a surface portion on which the protrusions are not formed. The reflected light from the liquid crystal display element can be satisfactorily guided to the observer, the observer can observe the display of the liquid crystal display element satisfactorily, and there is no fear that the display is greatly distorted.

The light from the light source enters 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 that enters the eyes of an observer located at a certain distance from the transparent substrate serving as the display surface does not normally meet the total reflection condition,
You can see the display without any problems. 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. When the light source is turned on, uniform and good illumination can be performed. The light plate becomes transparent, does not hinder the incidence of external light, and can achieve good display.

[0022]

FIG. 1 is a sectional view showing the structure of a liquid crystal display device 60 according to one embodiment of the present invention. The liquid crystal display device 60 is configured by disposing a liquid crystal display element 72 between a pair of polarizing plates 64a and 64b. The liquid crystal display element 72
A liquid crystal layer 66 is interposed between a pair of transparent substrates 65a and 65b made of glass or the like. In the present embodiment, the liquid crystal display element 72 includes a TFT (Thin F
It is a liquid crystal display element of an ilm Transistor type. In the present embodiment, a TFT method will be described as an example, but the present invention is not limited to this, and other methods, for example, MIM (Metal Insulator Meta) are used.
1) A method or a simple matrix method may be used.

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 arranged between the liquid crystal display element 72 and the polarizing plate 64a with air layers 71a and 71b interposed between the liquid crystal display element 72 and the polarizing plate 64a. A plurality of protrusions 61c are formed on the surface of the light guide plate 61 on the liquid crystal display element 72 side.

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 disposed 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
The 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.

Further, if necessary, the surface 61 of the light guide plate 61 may be used.
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 reflecting 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 TinO
xide) and an alignment film.

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. Then, on one surface, about 20μ in diameter
PMMA (polymethylmeta) having a thickness of about 2.5 mm and a conical protrusion having a height of about 12 μm.
The light guide plate 61 made of crylate 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 Co.
controlledbirefringence) type L
When C, a guest host type LC, a white tailor type guest host LC, a polymer dispersion type LC, or the like is used, the polarizing plate 64b can be omitted from the pair of polarizing plates 64a and 64b, so that a reflecting plate can be formed on the glass substrate 65b. .

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 and 63b were attached.

FIG. 3 is a diagram for explaining the operating principle of the light guide plate 61. The light 69 incident on the light guide plate 61 from the lamps 63a and 63b satisfies the condition of sin θ1> 1 / n, where θ1 is the incident angle with respect to the upper surface 61a of the light guide plate 61 and n is the refractive index of the light guide plate 61. The incident light 69 propagates inside the light guide plate 61 while being repeatedly reflected on the upper surface 61a and the lower surface 61b of the light guide plate 61.

At this time, when light enters the projection 61c formed on the lower surface 61b of the light guide plate 61, the projection 61c
The angle of incidence θ3 on the surface of is as follows: θ3 = θ1−θ2.

Here, when the incident angle θ3 satisfies the condition of sin θ3 <1 / n, the light 69 is projected onto the projection 61c of the light guide plate 61.
Out of the light guide plate 61 without being totally reflected by the surface of the light guide plate 61.

At this time, if the emission angle θ4 satisfies θ4> 90 ° −θ2, the emitted light enters the light guide plate 61 again from the lower surface 61b and exits from the upper surface 61a.

In order to prevent this, θ1 <θ2 + sin> −1 <｛sin (90 ° −θ2)
/ N｝ may be limited so as to satisfy the condition of / n 満 足.

In this embodiment, the light guide plate 61 is made of PM
Since MA was used, the refractive index n was about 1.5. Therefore, when θ1> 42 °, the illumination light 69 is totally reflected by the upper surface 61a of the light guide plate 61.

On the other hand, the condition that the illumination light 69 is not totally reflected on the surface of the projection 61c is θ2> 48 °.

The condition under which the light once emitted does not enter again is θ1 <74.5 °.

In this embodiment, the setting of the collimators 62a and 62b is set to 45 ° <θ1 <70 °, and θ2 = 50 ° in consideration of the processing accuracy of the light guide plate 61, the assembly accuracy of the illumination device, the accuracy of the collimator, and the like. As a result, no light leakage was observed in the direction of the upper surface 61a of the light guide plate 61, and it was confirmed that the illumination light was emitted only to the lower surface 62b. As a result of attaching to the liquid crystal display element 72, good display characteristics were obtained. Obtained.

The illumination light 69 propagating through the light guide plate 61 does not enter the tip of the conical or pyramidal projection 61c, so that the tip of the projection 61c may be flat. At this time, the protrusion 61c has a truncated cone or truncated pyramid shape.

FIG. 4 is a diagram showing another shape of the projection 61c. Here, a hemispherical projection 81c that is easy to process is used.
Is formed. Hereinafter, the operation principle will be described with reference to FIG.

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 n is the refractive index of the light guide plate 61. When the condition of sin θ11> 1 / n sin θ15> 1 / n is satisfied, the illumination light 89a and 89b are transmitted through the light guide plate 6
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
The incident angles θ13 and θ16 at are θ13 ≒ 90 ° −θ15 and θ16 ≒ 90 ° −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 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, n · sin θb = sin θa is established from Snell's law.

Here, when the light from the external lamps 63a and 63b enters the light guide plate 61, 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 sin θc> 1 / n.

Here, since θb + θc = 90 °, sin θb <1 / n <sin (90 ° −θb) from the above equations (16) and (17).

Θb satisfying this relational expression is θb <45 °.

At this time, the refractive index n is n> 1.42.

Therefore, when the refractive index n of the light guide plate 61 satisfies the above expression 21, the collimators 62a and 62b for limiting the incident angle of the light incident 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. In FIG. 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 n1, and the refractive index of a substance located on the side of the light guide plate 61 on the liquid crystal display element 72 is 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 operation principle 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 projection 61c, the light is transmitted to the transparent substrate 65a.
In a, it can be made closer to the normal direction. 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 reflector 68 is hardly totally reflected by the transparent substrate 65a of the liquid crystal display element 72. , More reflected light can be directed to the observer 70.

Further, the projections 61c of the light guide plate 61 are formed so as to be dotted, and the remaining surface of the surface 61b where the projections 61c are not formed is flat.
Can be satisfactorily observed by 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.

In the present invention, the projections are arranged on the light guide plate so as to be largely present in a region other than the pixel portion of the liquid crystal display element 72, for example, on a light shielding film between the pixels. Accordingly, the display is less affected by the projection, 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 (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 easy to see can be realized with only external light. By operating the light source device only when necessary, power consumption can be reduced.

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

Further, compared with the conventional illumination lamp system, a display with excellent uniformity can be obtained. Furthermore, compared to the conventional transparent reflection method, a display that is thin, light, bright, and excellent in uniformity can be obtained.

[0073]

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 light guide plate side of the liquid crystal display element. In the transparent substrate, it is possible to approach the normal direction. This makes it difficult for the reflected light incident on the liquid crystal display element and reflected by the reflection means to be totally reflected by 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.

Further, according to the present invention, since the light guide plate is formed with a plurality of protrusions corresponding to regions other than the pixel portion of the liquid crystal display element, a flat portion having no protrusion is formed. Exists, and this also allows the reflected light from the liquid crystal display element to be favorably guided to the observer, and the emitted light from the liquid crystal display element is not only projected, but also
Since the light passes through the flat surface and is guided to the observer, the observer can observe the display of the liquid crystal display element well.

[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 is a diagram for explaining an operation principle of a light guide plate 61 provided in the liquid crystal display device 60.

FIG. 4 is a diagram for explaining another operation principle of the light guide plate 61 provided in the liquid crystal display device 60.

FIG. 5 is a diagram for explaining another embodiment of the present invention.

FIG. 6 is a diagram for explaining still another operation principle of the light guide plate 61 used in the present invention.

FIG. 7 is a graph showing the relationship between the number of protrusions and the amount of light.

FIG. 8 is a cross-sectional view illustrating a configuration example of a liquid crystal display device using an illumination lamp method.

FIG. 9 is a cross-sectional view illustrating a configuration example of a liquid crystal display device using a reflecting mirror method.

FIG. 10 is a diagram illustrating a configuration example of a liquid crystal display device using a flat lamp system.

FIG. 11 is a cross-sectional view illustrating a configuration example of a liquid crystal display device using a light guide plate method.

FIG. 12 is a cross-sectional view illustrating a configuration example of a liquid crystal display device using a transparent reflection plate method.

[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 69a, 69b Light source light 70 Observer 71a, 71b Air layer 72 Liquid crystal display element 68a Reflecting surface

Claims (1)

(57) [Claims] 1. A liquid crystal having a liquid crystal layer interposed between a transparent substrate and a counter substrate disposed opposite to the transparent substrate and provided with a reflection means for reflecting incident light from the transparent substrate side. A display element; a light guide plate disposed on a transparent substrate side of the liquid crystal display element; and a light source disposed on a side surface of the light guide plate. The surface of the light guide plate facing the liquid crystal display element includes at least the liquid crystal display. A plurality of protrusions are formed so as to correspond to regions other than the pixel portion formed in the element, 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 to 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.
Where n1 <n · sin θ is satisfied.