JPH05158033A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To attain a bright display by arranging a light guiding plate at a liquid crystal display element on the side of a transparent substrate, arranging a light source on the outward side of the flank of the light guiding plate and specifying the angle of incidence of light source light on the light guiding plate. CONSTITUTION:The light guiding plate 61 is arranged on the front side, i.e., observer 70 side of the liquid crystal display element 72 and a couple of lamps 63a and 63b are arranged as the light source on the outward side of the opposite flank of the light guiding plate 61. The angle theta of incidence of the light source light 69 on the internal surface of the light guiding plate 61 on the opposite side from the liquid crystal display element 72 is set so as to satisfy an inequality. In the inequality, (n) is the refractive index of the light guiding plate 61, n1 the refractive index of a material of the light guiding plate 61 which is positioned on the opposite side from the liquid crystal display element 72, n2 the refractive index of a material of the light guiding plate 61 which is positioned on the side of the liquid crystal display element, and theta the angle of incidence of the light source light 69 on the surface of the light guiding plate 61 on the opposite side from the liquid crystal display element 72. The light source light 69a is therefore made incident on the liquid crystal display element 72 without being emitted to the side of the observer 70 and only part of display light, reflected by a reflecting plate 68, which does not match the total reflection conditions of the light guiding plate 61 passes through the light guiding plate 61.

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 word processors and personal computers, viewfinders for portable video tape recorders, and various monitors for image signals. Regarding the device.

[0002]

2. Description of the Related Art ELs (Electro Luminescence), CRTs (Cathode Ray Tubes), LEDs (Light Emmiting Diodes), etc. are display devices that emit light by themselves, while liquid crystals are themselves. It is a display device that does not emit light but receives light for display. Therefore, a light source is needed to make the display visible to the human eye. Conventionally, many methods have been proposed and put into practical use as a light source device for a direct-view type liquid crystal display device. The main ones are shown below.

Illumination Lamp System FIG. 5 is a sectional view showing an example of the configuration of a liquid crystal display device using a light source device of the illumination lamp system. Lamps 11a, 11b
Are arranged on the front side and the 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 projected to the liquid crystal display device 12 again to become display light. In the case of this lighting lamp system,
The lamps 11a and 11b, which are 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.

Reflecting Mirror Method FIG. 6 is a diagram showing a configuration example of a liquid crystal display device using a reflecting mirror type light source. The reflecting mirror method is a method that is often used because of high light utilization efficiency and high brightness. The reflection plate 22 is disposed on the side of the lamp 23 opposite to the liquid crystal display device 24, and the light from the lamp 23 is efficiently emitted to the front surface (the liquid crystal display device 24 side). There is a problem that the high-brightness portion is biased to the periphery of the lamp 23 and the uneven brightness is apt to occur with the reflection plate 22 alone. Therefore, the diffusion plate 21 is disposed in front of the lamp 23, and the thickness of the diffusion plate 21 is changed to uniform the brightness. Improve sex. Light from the diffusion plate 21 is projected onto the liquid crystal display device 24.

Flat Plate Lamp System FIG. 7 is a diagram showing a configuration of a liquid crystal display device using a flat plate lamp light source device. 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 surface 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 by the discharge between a and 32b. Light from the fluorescent screen 31 is projected onto the liquid crystal display device 37. In the flat plate lamp system, the lamp itself has a flat plate shape and only needs to be arranged on the back side of the liquid crystal display device 37, and there is an advantage that the light utilization efficiency is high because an optical system is unnecessary.

Light Guide Plate System FIG. 8 is a diagram showing the configuration of a liquid crystal display device using a light source device of the light guide plate system. The light emitted from the lamp 41 is
Light guide plate 43 made of acrylic resin or the like having excellent translucency
The light is guided by multiple reflections on the inner surface of the. A reflection plate 42 is provided on the surface of the light guide plate 43 opposite to the liquid crystal display device 45, and the light from the lamp 41 is extracted only from the front surface through the diffusion plate 44 and projected onto the liquid crystal display device 45. To be done. Here, the lamp 41 often uses a reflector 42 and a slit (not shown) or the like to collect light to improve the light utilization efficiency. In principle, this light source device does not totally reflect 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 brightness uniformity, it can be applied to thin electronic devices using a portable liquid crystal display device.

EL system EL is a thin and lightweight planar light source device, which is excellent in brightness uniformity and has characteristics as a light source device of a liquid crystal display device, but has low surface brightness and light color. Selection range is narrow,
It has drawbacks such as rapid color deterioration during use, and it has been replaced with a fluorescent lamp in accordance with colorization of liquid crystal display devices. However, in recent years, the development of EL having high brightness and long life has progressed, and the EL lamp has been reviewed again as the liquid crystal display device has become thinner.

Transparent Reflector Method FIG. 9 is a diagram showing a configuration of a liquid crystal display device using a transparent reflector type light source device. The light emitted from the lamp 51 is reflected by the front reflection plate 54 disposed on the front surface (on the observer 55 side) of the liquid crystal display device 52, transmitted through the liquid crystal display device 52, and reflected by the back reflection plate 53, Liquid crystal display device 5 again
After passing through 2 and passing through the front reflection plate 54, it reaches an observer 55 who views the liquid crystal display device 52. A liquid crystal display device using this light source device has not yet been put to practical use.

[0009]

In recent years, downsizing of office automation equipment such as word processors and personal computers,
It is becoming more portable. In consideration of portability, it is essential for portable devices to be thin and lightweight, and keyboards, display devices, batteries, etc. are rapidly becoming thinner and lighter. On the other hand, it is also important to reduce power consumption, and since the reflective liquid crystal display device can see the display only with outside light in an environment with well-lit environment, display devices without a light source device are widely used. ing. However, in this type of liquid crystal display device, when the surrounding illumination becomes dark, the display becomes difficult to see, and there is a problem in that it is difficult to use.

In order to solve these problems, lightweight,
There is a need for a reflective liquid crystal display device that is thin and has a light source device that can uniformly illuminate the entire surface of the display device. Since the reflection type liquid crystal display device cannot illuminate from the back side, a transparent light source device must be arranged in front of the display surface. A reflective liquid crystal display device equipped with a transparent front-mounted light source device can see the display only by outside light without using the built-in light source device when the surrounding illumination is bright. When it is sufficient, the light source device can be used only when necessary, such as using the light source device built into the device. Therefore, the power consumption can be reduced.

In the case of the above-mentioned six types of conventional techniques, the reflecting mirror system, the flat plate lamp system, and the EL system cannot be installed in front of the liquid crystal display device due to their structures.
Further, the light guide plate method cannot be placed in front because it has a reflector and the light source device is not transparent.

Both the illumination lamp system and the transparent reflector system can be installed in front of the liquid crystal display device.
There is a problem that uniform lighting 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) and the like, the liquid crystal molecules in the liquid crystal display element are twisted by 90 to 270 degrees as an initial orientation, and the liquid crystal display element is arranged between a pair of polarizing plates. The display is performed by utilizing the optical property, that is, the optical rotation characteristic when no electric field is applied and the optical rotation elimination characteristic when a voltage is applied. Since the light source device must be installed, the light from the light source passes through each polarizing plate twice, that is, four times in total. Therefore, there is a problem that the absorption of light by the polarizing plate is large, the utilization efficiency of the light from the light source is lowered, and the display becomes dark.

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

[0014]

The present invention comprises a transparent substrate,
A liquid crystal display element, which is arranged so as to face the transparent substrate and has a liquid crystal layer interposed between the transparent substrate and a counter substrate provided with a reflecting means for reflecting incident light from the transparent substrate side; Of the substance located on the side opposite to the liquid crystal display element of the light guide plate, including a light guide plate arranged on the transparent substrate side and a light source arranged on the side surface of the light guide plate. When the refractive index is n1, the refractive index of the substance located on the liquid crystal display element side of the light guide plate is n2, 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,

[0015]

## EQU1 ## A liquid crystal display device characterized by satisfying the condition of n1 <n.sin.theta. <N2.

[0016]

According to the present invention, the reflection means is arranged on the side of the counter substrate which is arranged so as to face the transparent substrate, and the liquid crystal display element which reflects the light incident from the side of the transparent substrate is used to transmit / transmit the light.
The display is performed by controlling the interruption. In the liquid crystal display device of the present invention, the light guide plate is arranged on the transparent substrate side of the liquid crystal display element, and the light source is arranged 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 satisfies the relational expression of the above mathematical expression 1, that is, the total reflection is performed, and the reflection is performed. The light is set so as not to be totally reflected on the inner surface of the light guide plate on the liquid crystal display element side. Therefore, 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 reflector and only the light that does not meet the conditions for total reflection by the light guide plate out of the display light transmitted through the liquid crystal display element passes through the light guide plate. That is, the light that reaches the eyes of an observer located at a certain distance from the transparent substrate that serves as the display surface does not normally meet the total reflection condition, so that the display can be viewed without any problem. Further, when the light source is turned off, the light guide plate becomes transparent, which does not hinder the entrance of external light from the transparent substrate side, and the display based on the external light is performed.

As described above, the light source device including the light guide plate and the light source can be installed on the front surface (display surface) side of the liquid crystal display element, and uniform and good illumination can be performed when the light source is turned on and when the light source is turned off. Since the light plate becomes transparent, it does not hinder the incidence of external light, and good display can be realized.
Further, the light source device has a thin flat plate shape and can be installed between the polarizing plate and the liquid crystal display element. In this case, compared to the conventional liquid crystal display device in which the light source device is arranged outside the polarizing plate, the number of times of passing through the polarizing plate is reduced by one, so that light absorption by the polarizing plate is reduced and a bright display is realized. You can

[0019]

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 the pair of polarizing plates 64a and 64b.
Is 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 is interposed. In this embodiment, the liquid crystal display element (Thin Film Transistor) 72 has a TF
This is a T-type liquid crystal display element. In this embodiment, the TFT method will be described as an example, but the present invention is not limited to this, and another method such as MIM (Metal Insulator Meta) is used.
l) method or simple matrix method may be used.

A reflecting plate 68 is arranged on the side of the polarizing 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 provided with irregularities so as to uniformly reflect the incident light from the liquid crystal display element 72 side.

A light guide plate 61 is arranged between the liquid crystal display element 72 and the polarizing plate 64a with an air layer 71 interposed between the liquid crystal display element 72 and the polarizing plate 64a. Lamps 63a and 63b are arranged on the outer sides of the opposite side surfaces of the light guide plate 61, respectively. Collimators 62a and 62b are arranged between the light guide plate 61 and the lamps 63a and 63b, respectively. Collimator 62
a and 62b are lights emitted from the lamps 63a and 63b,
The angle of incidence on the upper surface 61a of the light guide plate 61 is limited. The light guide plate 61 and the transparent substrate 65a, the transparent substrate 65b and the polarizing plate 64b, the polarizing plate 64b and the reflecting plate 68 are adhered by transparent adhesives 67a, 67b and 67c, respectively.

Here, the light guide plate 61 and the glass substrate 65a.
, Liquid crystal layer 66, transparent substrate 65b, and polarizing plate 64b
The transparent adhesives 67a, 67b and 67c are selected from materials so that their refractive indices are substantially equal to each other.

Here, the collimators 62a and 62b are used to limit the incident angle of the incident light from the lamps 63a and 63b to the light guide plate 61, but other methods can be used if the incident angle can be limited within a certain range. You can use it. For example, it is possible to limit the incident light by attaching slits to the lamps 63a and 63b, and at the portions near the lamps 63a and 63b, the incident angle to the light guide plate 61 is small and total reflection does not occur. Therefore, the light guide plate 6
Although the light from the light source leaks directly from the surface 1, this portion may be shielded. Moreover, if 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 total reflection condition. In this case, the collimator may be omitted.

If necessary, the surface 61 of the light guide plate 61 is provided.
antireflection film on either or both of a and 61b,
Coating for facilitating total reflection or coating for preventing scratches or repairing scratches may be performed.

Further, the reflecting plate 68 and the transparent substrate 65b,
Alternatively, if the light guide plate 61 and the transparent substrate 65a can be fixed by a means other than a transparent adhesive, a filler such as silicon oil may be filled instead of the transparent adhesive.

Furthermore, in this embodiment, the light guide plate 61 is adhered onto the transparent substrate 65a with the transparent adhesive 67a, but the light guide plate 61 may be used as the transparent substrate 65a. That is, in this case, the transparent substrate 65a and the transparent adhesive 67a can be omitted.

Furthermore, the upper surface 61a of the light guide plate 61
The surface of may be coated with a material having a smaller refractive index than the material of the light guide plate. In this case, when the refractive index of the coating agent is n1, the refractive index of the light guide plate 61 is n, and the incident angle of the light 69a to the light guide plate 61 is θ,

[0028]

If sin θ> n1 / n is satisfied, the light incident on the light guide plate 61 is totally reflected between the light guide plate 61 and the coating agent, so that the polarizing plate 64a can be directly bonded onto the light guide plate 61. Furthermore, if the refractive indexes of the light guide plate 61 and the polarizing plate 64a are set to appropriate values, the polarizing plate 64
a can be directly adhered to the light guide plate 61.

2A to 2D are process drawings for explaining a method of manufacturing the liquid crystal display device 60. A transparent substrate 65b is formed using borosilicate glass, and an amorphous silicon TFT (Thin Film) is formed on one surface of the transparent substrate 65b by a general procedure.
Transistor) to form pixel electrodes in a matrix.
A resin such as polyimide is applied to the surface and a rubbing treatment 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) which is a common electrode is formed on one surface of the transparent substrate 65a.
Oxide) and an alignment film are formed.

In step a3, the transparent substrates 65a and 65b are arranged such that the electrode formation surfaces face each other, and a spacer is interposed between the substrates to bond them together. In step a4, TN (Twisted Nematic) is applied between the transparent substrates 65a and 65b.
Enclose the liquid crystal. Here, the liquid crystal is ZLI made by Merck.
Although -1565 is used, other 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 composited, is used, a polarizing plate is not required, and thus the light utilization efficiency is improved. When a guest-host type liquid crystal material is used, one polarizing plate can display. In addition, guests
Among the host type, particularly when a white tailor type liquid crystal material is used, a polarizing plate is not required like the liquid crystal material in which an organic polymer and a liquid crystal compound are combined. On the other hand, as the TN liquid crystal material, many materials other than the materials shown in this embodiment are known, and other materials may be used.

Then, in step a5, the polarizing plate 64b is adhered to the transparent substrate 65b with an epoxy-based transparent adhesive 67b. Then, in step a6, an Al reflective plate 68 subjected to air line processing is adhered to the polarizing plate 64b with an epoxy-based transparent adhesive 67c. After that, in step a7, the plate thickness is about 2.5 m
The borosilicate glass of m was adhered onto the transparent substrate 65a with the transparent adhesive 67a to form the light guide plate 61.

In this embodiment, the Al reflector 68 is replaced by the polarizer 64.
Although the example of adhering to b is shown, the 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, etc., the polarizing plate 64b can be omitted from the pair of polarizing plates 64a, 64b, so that it is reflected on the glass substrate 65b. A plate can be formed.

Subsequently, in step a8, the polarizing plate 64a was attached to the upper surface 61a of the light guide plate 61 with a space of about 1 mm. After fixing these to a frame not shown, step a
9, the collimators 62a and 62b and the lamp 63
a and 63b were attached.

FIG. 3 is a diagram for explaining the operation of the light guide plate 61. The light incident on the light guide plate 61 from the lamps 63a and 63b is the light 69 reflected on the upper surface 61a of the light guide plate 61.
a and light 69b that is directly incident on the reflecting plate 68. Here, when the refractive index of the light guide plate 61 is n, the incident angle θ of the light 69 a to the light guide plate 61 is

[0035]

When the condition of sin θ> 1 / n is satisfied, the light 69a is totally reflected by the upper surface 61a of the light guide plate 61 and is incident on the reflection plate 68. In this embodiment, since glass is used as the light guide plate 61, n is about 1.5, and therefore the incident angle θ is 42 degrees or more. Although a glass plate is used as the light guide plate in this embodiment, a material other than glass may be used as long as it can guide light uniformly without attenuation and has an appropriate refractive index. For example, PMMA (polymethylmetacrylate), CR-39
Materials such as resin, polycarbonate, polyvinyl chloride and polyester may be used.

On the other hand, the light 69 traveling directly to the reflecting plate 68
Since the refractive index of the material through which light passes is substantially the same as the refractive index of the light guide plate 61, b goes straight without being affected by reflection or refraction. The light that has reached the reflecting surface 68a of the reflecting plate 68 is irregularly reflected by the reflecting surface 68a and is made uniform. Then, the adhesive 67c, the polarizing plate 64b, the adhesive 67b, and the transparent substrate 65.
b, the liquid crystal layer 66, the transparent substrate 65a, the adhesive 67a, the light guide plate 61, the air layer 71, and the polarizing plate 64a are sequentially passed to reach the observer 70. At this time, for the purpose of improving the uniformity of light, a diffusing plate may be placed between the reflecting plate 68 and the polarizing plate 64b.

It is also possible to process the light guide plate 61 for the purpose of homogenizing the light emitted from the light guide plate 61 toward the reflection plate 68. For example, the lower surface 61b of the light guide plate 61
The amount of light extracted from the light guide plate 61 can be controlled by coating with a film having a low refractive index and partially removing it by etching. That is, the coating film is densely formed in the vicinity of the lamps 63a and 63b and sparsely formed in the areas away from the lamps so that the illumination is uniform on the entire surface of the display device. The amount of light can be made uniform.

FIG. 4 is a diagram for explaining the principle of the present invention. As shown in FIG. 4A, the refractive index of the substance in contact with the upper surface 61a of the light guide plate 61 is n1, and the light guide plate 61 is
Is n, and the refractive index of the substance in contact with the lower surface 61b of the light guide plate 61 is n2. As shown in FIG. 4B, when the incident angle of the light incident on the light guide plate 61 on the upper surface 61a and the lower surface 61b is θ, the condition for total reflection on the upper surface 61a is

[0039]

(4) n · sin θ> n1. In addition, the condition that the lower surface 61b does not totally reflect is

[0040]

(5) n · sin θ <n2.

Therefore, the conditions for total reflection on the upper surface 61a and not total reflection on the lower surface 61b are expressed by Equations 4 and 5:

[0042]

[Equation 6] n1 <n · sin θ <n2 That is,

[0043]

(7) sin ⁻¹ (n1 / n) <θ <sin ⁻¹ (n2 / n).

Here, the larger the refractive index n2 / n is and the smaller the refractive index n1 / n is, the wider the range of θ is, and the amount of light that can be extracted increases. When n≈n2, n2 / n≈
1, and almost all the light totally reflected by the upper surface 61a is emitted from the lower surface 61b.
When the refractive indices of the substructures such as 2 are all equal to n,
The light goes straight without refraction.

Furthermore, when n <n2 and all the refractive indices of the lower structure such as the liquid crystal display element 72 are n2, the lower surface 61b is refracted as shown in FIG. 4 (4). , Then go straight.

As described above, according to this embodiment, the light guide plate 61, the collimators 62a and 62b, and the lamps 63a and 63b that form the light source device can be arranged in front of the liquid crystal display element 72 (on the observer 70 side). it can. by this,
In the reflective liquid crystal display device, even when the surroundings are dark, by turning on the light source, the light necessary for display is given to the liquid crystal display element 72, and an easy-to-see display is possible. Also,
When the surroundings are bright, the light guide plate 61 becomes transparent by turning off the light source, and it is possible to realize a display that is sufficiently easy to see even with outside light. Thus, by operating the light source device only when necessary, power consumption can be reduced. Further, since the light guide plate 61 can be disposed between the polarizing plate 64a and the liquid crystal display element 72, the number of times light passes through the polarizing plate can be reduced by one, and the light guiding plate 61 can be placed outside the polarizing plate 64a. A brighter display can be realized as compared with the case of arranging in.

In this embodiment, the lamps 63 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.

Further, as compared with the conventional illumination lamp system, a display having excellent uniformity can be obtained. Furthermore, as compared with the conventional transparent reflection method, a thin, lightweight, bright and excellent display can be obtained.

[0049]

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 element, and the light from the light source does not directly enter the eyes. It is possible to uniformly illuminate the liquid crystal display element. As a result, it becomes possible to illuminate the reflective liquid crystal display device, which has been difficult to illuminate conventionally. Further, since the light guide plate is thin, it is suitable for a portable OA device equipped with a reflective liquid crystal display device. In addition, the light source is turned off when the surroundings are bright and can be illuminated by external light, and it is turned on when the surroundings are dark.
It is possible to reduce power consumption. In this way, it is possible to realize a lightweight, thin, and low power consumption reflective liquid crystal display device.

[Brief description of drawings]

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

2A to 2C are process diagrams illustrating a method of manufacturing the liquid crystal display device 60.

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

FIG. 4 is a diagram for explaining the principle of the present invention.

FIG. 5 is a cross-sectional view showing a configuration example of a liquid crystal display device of an illumination lamp system.

FIG. 6 is a cross-sectional view showing a configuration example of a liquid crystal display device of a reflecting mirror system.

FIG. 7 is a diagram showing a configuration example of a liquid crystal display device using a flat lamp system.

FIG. 8 is a cross-sectional view showing a configuration example of a liquid crystal display device using a light guide plate method.

FIG. 9 is a cross-sectional view showing a configuration example of a liquid crystal display device using a transparent reflector method.

[Explanation of symbols]

 60 Liquid crystal display device 61 Light guide plate 62a, 62b Collimator 63a, 63b Lamp 64a, 64b Polarizing plate 65a, 65b Transparent substrate 66 Liquid crystal layer 67a, 67b, 67c Transparent adhesive agent 68 Reflector plate 69a, 69b Light source light 70 Observer 71 Air layer 72 liquid crystal display element 61a upper surface 61b lower surface 68a reflective surface

Claims (1)

[Claims] 1. A liquid crystal layer is interposed between a transparent substrate and a counter substrate which is arranged so as to face the transparent substrate and which has a reflecting means for reflecting incident light from the transparent substrate side. A liquid crystal display element, which includes a liquid crystal display element, a light guide plate arranged on the transparent substrate side of the liquid crystal display element, and a light source arranged on a side surface of the light guide plate, wherein the refractive index of the light guide plate is n. The refractive index of the substance located on the opposite side to n is set to n1, the refractive index of the substance located on the liquid crystal display element side of the light guide plate is set to n2, and the light source light is incident on the surface of the light guide plate opposite to the liquid crystal display element side. A liquid crystal display device characterized by satisfying a condition of n1 <n · sin θ <n2, where θ is an angle.