JP2002287138A - Liquid crystal display device and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which brightness and display uniformity are not adversely affected by easily optimizing the distance between a light guide plate and a light source in manufacturing so as to suppress manufacturing cost increase and a method for manufacturing the device. SOLUTION: The liquid crystal display device is provided with a liquid crystal display element to display a picture and an illuminating means having an LED(light emitting diode) 9 and a light guide plate 10 making light from the LED 9 incident thereon from a side face and emitting the light to the liquid crystal display element. A case 11 to attach the LED 9 and the light transmission plate 10 in a fixed state is provided. Positioning parts such as difference in level 12, a protruding part 13, projecting parts 14, 16, 18, recessing parts 15, 17, a bent part 19, etc., to maintain a specified distance between the LED 9 and the side face of the light transmission plate 10 is formed on the case 11 or on the light guide plate 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device used for a liquid crystal display device such as a portable information terminal and a method for manufacturing the same, and more particularly to a lighting device for a liquid crystal display device and a method for manufacturing the same.

[0002]

2. Description of the Related Art Liquid crystal display devices can be broadly classified into transmission type liquid crystal display devices and reflection type liquid crystal display devices.

In a transmissive liquid crystal display device, polarizing plates are arranged on the light incident side and the light emitting side, and the polarization state of linearly polarized light incident through the incident side polarizing plate is modulated by a liquid crystal layer. An image is displayed by controlling the amount of light emitted from the polarizing plate on the emission side.

On the light incident side of a transmission type liquid crystal display device,
Generally, a light emitting source such as a fluorescent tube, which is an illuminating means called a backlight, for illuminating the liquid crystal display device from behind (incident side) is arranged.

[0005] The reflection type liquid crystal display device has a reflection plate and a polarizing plate on the observer side. The linearly polarized light that has entered through the polarizing plate is reflected by the reflecting plate, and while reaching the polarizing plate again, the polarization state is modulated by the liquid crystal layer, and the amount of light emitted from the polarizing plate is controlled.

[0006] The reflection type liquid crystal display device uses the ambient light to perform display, and thus has the characteristics of being lightweight, thin, and low in power consumption. In addition, a reflective liquid crystal display device can significantly reduce the visibility of an image even in a very bright environment, such as in direct sunlight, while a transmissive liquid crystal display device or the like significantly reduces the visibility of an image. Is also visually recognizable. For this reason, reflective liquid crystal display devices tend to be widely applied to portable information terminals and the like.

A reflection type liquid crystal display device has two glass substrates bonded to each other, and has a liquid crystal layer between them. 2
A deflecting plate is provided on the observer side surface of the glass substrates, and a reflecting plate is provided on the opposing surface. The two glass substrates are TFT (Thin Fil
m Transistor: thin film transistor) glass substrate and CF
(Color Filter) This is a glass substrate. TFT glass substrate is a TFT for controlling the liquid crystal layer
Elements, electrodes, and the like are provided, and an area corresponding to a region for inputting these signals is required. From this, CF
The glass substrate is smaller than the TFT glass substrate.

[0008] However, the reflection type liquid crystal display device also has the following problems. As described above, since the ambient light is used very much, the reflection type liquid crystal display device has a very high degree of display luminance depending on the surrounding environment. For this reason, the user cannot fully recognize the display in a dark environment. Therefore, in a reflection type liquid crystal display device, if sufficient ambient light cannot be obtained, auxiliary lighting means is required, and a front light lighting device is used.

In general, a lighting device for a liquid crystal display device such as a liquid crystal television or a portable information terminal is provided with a CCFT (Cold).
Cathode Fluorescent tubes (cold cathode tubes) have been used as light sources (auxiliary lighting means). However, using a CCFT requires an inverter with high power consumption for lighting. That is, a lighting device using a CCFT as a light source is not suitable for a device requiring low power consumption such as a portable information terminal. Therefore, in a device requiring low power consumption, an LED (Light Emitting Diode) is used as a light source of a lighting device.

On the other hand, as described above, the reflection type liquid crystal display device tends to be applied to a large number of portable information terminals and the like, and it is necessary to improve the portability of the product.
Miniaturization is required. Here, as auxiliary lighting means for reducing the size and weight, for example, JP-A-11-125816
The prior art is disclosed in a gazette.

In this conventional liquid crystal display device, as shown in FIG. 7, the light source 101 is mounted so that light from the light source 101 is incident from one end of the glass substrate 102 toward the inside.

Light entering the glass substrate 102 from the light source 101 is applied to the polarizing plate 1 provided on the surface of the glass substrate 102.
By moving toward the other end side while refracting between the light emitting device 03 and the opposing surface thereof, the entire glass substrate 102 simultaneously emits light in a planar manner, thereby acting as a lighting device. Therefore, the arrangement of the light guide plate can be omitted, and the size and weight can be reduced.

However, the above-mentioned conventional auxiliary lighting means has the following problems. As shown in FIG. 8, when light A from the light source 101 passes through the inside of the glass substrate 102, the light A does not pass through the polarizing plate 103. Therefore, the light A does not become linearly polarized light but the liquid crystal layer 104.
The amount of light emitted from the liquid crystal display element through the polarizing plate 105 is not controlled, so that the contrast is reduced and the display quality is deteriorated.

From the above, when the light from the light source 101 of the lighting device passes through the liquid crystal layer 104, the polarizing plate 103
It needs to be linearly polarized light incident through Therefore, a light guide plate is required for the light A from the light source 101 as well as the ambient light.

Here, a conventional reflection type liquid crystal display device having a light guide plate will be described below.

As shown in FIG. 9, this reflection type liquid crystal display device has a configuration including a light guide plate 201 and a liquid crystal display element 202.

The liquid crystal display element 202 has a structure in which two glass substrates are bonded to each other, and a liquid crystal layer is provided therebetween. A polarizing plate 2 is placed on the observer side of the two glass substrates.
03, a reflection plate (not shown) is provided on the facing surface. One of the two glass substrates is a TFT glass substrate 204,
The other is a CF glass substrate 205. LE as the light source
D <b> 206 is arranged at a position where light can enter from the end of the light guide plate 201.

Generally, when the LED 206 is used as a light source of a lighting device, the light from the LED 206 has a directional characteristic as shown in FIG. Therefore, there is a problem that a screen having a uniform brightness cannot be obtained from the entire display screen.

That is, in a state where the LED 206 and the light guide plate 201 are arranged apart from each other more than necessary, FIG.
As shown in (2), the light from the LED 206 enters the light guide plate 201 only in the range of the shaded portion B, and sufficient brightness cannot be secured.

Conversely, when the LED 206 and the light guide plate 201 are arranged closer to each other than necessary, as shown in FIG. 10B, a sufficient brightness is secured in the area C of the light guide plate 201. Can not. Therefore, as shown in FIG. 10C, the light from the LED 206 is efficiently incident on the light guide plate, and the LED 206 is brightened without unevenness as a whole.
It is desirable to provide a predetermined distance D that is an optimum distance between the light guide plate 201 and the light guide plate 201.

[0021]

However, in the conventional reflection type liquid crystal display device provided with the light guide plate, the light source is arranged on the side of the illuminated body and then the light guide plate is arranged. A slight shift occurs in the distance between the light plate and the light source. Therefore, the LED 206 and the light guide plate 201
Is not constant, which has a problem of adversely affecting brightness and display unevenness.

On the other hand, Japanese Patent Application Laid-Open No. 2000-221 discloses a method that does not require much
There is a backlight for liquid crystal disclosed in Japanese Patent Publication No. 502-502. In this liquid crystal backlight, by processing the end of the light guide plate, the light that passes directly to the liquid crystal panel is totally reflected and returned to the inside of the light guide plate, thereby suppressing local high-luminance light emission.

However, in the backlight for liquid crystal,
By processing the edges of the light guide plate, it is necessary to perform complicated and surface-accurate processing, which requires total reflection of light that passes directly to the liquid crystal panel and returns the light into the light guide plate. There were problems such as invitation.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a light guide plate and a light source at the time of manufacturing so as not to adversely affect brightness and display unevenness. The present invention provides a liquid crystal display device and a method for manufacturing the same, which can easily optimize the distance of the liquid crystal display and avoid an increase in manufacturing cost.

[0025]

In order to solve the above-mentioned problems, a liquid crystal display device of the present invention has a liquid crystal display element for displaying an image, at least one or more light sources, and light from the light sources. A liquid crystal display device having illumination means having a light guide plate for emitting light to the liquid crystal display element, wherein a case for attaching the light source and the light guide plate in a fixed state is provided, and the case or the light guide plate is provided. Is characterized in that a positioning portion for maintaining a predetermined distance between the light source and the side surface of the light guide plate is formed.

According to the above-mentioned invention, the predetermined distance is provided between the light source and the side surface of the light guide plate, and the light source and the light guide plate are fixed by the case. That is, for example, in order to attach and fix the light guide plate to the case after attaching and fixing the light source to the case, it is only necessary to set the light guide plate on the positioning portion of the case.

As a result, since the distance between the light source and the side surface of the light guide plate via the case is constant, the amount of light incident on the light guide plate is also constant, so that the brightness and display unevenness of the liquid crystal display device are not adversely affected. Can be

According to the present invention, the distance between the light source and the side surface of the light guide plate can be maintained at a predetermined distance only by forming the positioning portion on the case or the light guide plate. Not even.

Therefore, in order to avoid adverse effects on brightness and display unevenness, the distance between the light guide plate and the light source can be easily optimized at the time of manufacturing, and a liquid crystal display capable of avoiding an increase in manufacturing cost can be avoided. An apparatus can be provided.

Further, the liquid crystal display device of the present invention is characterized in that, in addition to the above configuration, the light guide plate is guided to the positioning portion by being inserted into the case.

According to the above configuration, since the light guide plate is fixed inside the case, the light source and the light guide plate are housed in the same case. Therefore, the light source and the light guide plate can be easily and precisely arranged at the optimized positions, and the illumination means and the liquid crystal display element can be integrated.

This makes it possible to provide a liquid crystal display device in which the amount of light incident on the light guide plate becomes constant and does not adversely affect brightness and display unevenness.

Further, in the liquid crystal display device of the present invention, in addition to the above configuration, the positioning portion includes a concave portion formed on one of the case and the light guide plate and a convex portion formed on the other to fit the concave portion. Alternatively, it is characterized in that the light guide plate or the light guide plate has a stepped portion formed on the case so as to be in contact with the end of the light guide plate.

According to the above configuration, it is possible to prevent the light guide plate from moving in the direction approaching the light source and in the direction coming out of the case. Therefore, a certain distance can be maintained between the light source and the light guide plate with a specific and simple configuration, and an increase in manufacturing cost can be prevented.

Further, in the liquid crystal display device of the present invention, in addition to the above configuration, the predetermined distance D between the light source and the side surface of the light guide plate is such that the thickness of the light guide plate is E, and the light guide plate out of the light emitted from the light source. Is defined as D = (E / 2) / tan (θ / 2), where θ is an emission angle of light effective for illumination.

With the above configuration, it is possible to determine the optimum distance between the light source and the side surface of the light guide plate such that a necessary and sufficient amount of light enters the light guide plate. Further, the optimum distance between the light source and the side surface of the light guide plate can be obtained from the type of the light source and the thickness of the side surface of the light guide plate. Therefore, the amount of light incident on the light guide plate is optimal and constant regardless of the type of light source.

Therefore, it is possible to provide a liquid crystal display device which does not adversely affect brightness and display unevenness. In addition, there is an effect that the thickness variation of each member other than the light guide plate does not affect the distance between the side surface of the light guide plate and the light source.

In order to solve the above-mentioned problems, a method of manufacturing a liquid crystal display device according to the present invention comprises: a liquid crystal display element for displaying an image; at least one light source; A light guide plate that emits light to the liquid crystal display element; and a lighting method having a light guide plate, wherein the light source is fixed to the case and then the light guide plate is fixed to the case, while the light source is fixed to the case. When the light guide plate is fixed to the case after being fixed to the case, a predetermined distance between the light source and the light guide plate is maintained by a positioning portion formed on the case or the light guide plate.

According to the above method, even if the light guide plate is attached to the case after the light source is previously arranged in the case, the distance between the light source and the side surface of the light guide plate is constant without any deviation. Therefore, the amount of light incident on the light guide plate is also constant, and does not adversely affect brightness and display unevenness.

As a result, in order not to adversely affect the brightness and the display unevenness, the distance between the light guide plate and the light source can be easily optimized at the time of manufacturing, and the liquid crystal which can avoid an increase in manufacturing cost can be avoided. A method for manufacturing a display device can be provided.

The method of manufacturing a liquid crystal display device according to the present invention is characterized in that, in addition to the above-described method, a light guide plate is inserted into a case to guide it to a positioning portion.

According to the above method, since the light guide plate is fixed inside the case, the light source and the light guide plate are housed in the same case. Therefore, it is possible to arrange the light source and the light guide plate at precisely optimized positions, and to integrate the illumination means and the liquid crystal display element. This makes it possible to provide a method of manufacturing a liquid crystal display device in which the amount of light incident on the light guide plate is also constant and does not adversely affect brightness and display unevenness.

Further, in addition to the above-mentioned method, the method of manufacturing a liquid crystal display device of the present invention has a thickness E of the light guide plate, and enters the side surface of the light guide plate out of the light emitted from the light source, which is effective for illumination. When the emission angle of light is θ, the predetermined distance D between the light source and the light guide plate is determined by D = (E / 2) / tan (θ / 2).

By the above method, it is possible to determine the optimum distance between the light source and the side surface of the light guide plate such that a necessary and sufficient amount of light is incident on the light guide plate. Further, the optimum distance between the light source and the light guide plate can be determined from the type of the light source and the thickness of the light guide plate.

Therefore, the amount of light incident on the light guide plate is optimal and constant regardless of the type of light source.
Therefore, a method for manufacturing a liquid crystal display device that does not adversely affect brightness and display unevenness can be provided. In addition, there is an effect that the thickness variation of each member other than the light guide plate does not affect the distance between the light guide plate and the light source.

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS.

As shown in FIGS. 2 and 3A, the reflection type liquid crystal display device 1 as the liquid crystal display device of the present embodiment is shown.
Is a configuration in which a front light illuminating device 3 as illuminating means is arranged on a reflective liquid crystal display device 2 as a liquid crystal display device.

As shown in FIG. 2, the reflection type liquid crystal display element 2 comprises a TFT glass substrate 4 and a CF glass substrate 5 bonded together. In the TFT glass substrate 4, CF
The part not bonded to the glass substrate 5 includes a driver LSI (Large Scale Integrated Circuit) for driving a liquid crystal.
it: large-scale integrated circuit (IC) 6, a liquid crystal driving power supply (not shown), and a flexible printed circuit (FPC) for inputting signals.
s: flexible printed wiring board) 7.

The front light illumination device 3 is shown in FIG.
As shown in the figure, LED 9 (Light Emitting
Diode: light emitting diode) and F connected to LED 9
It comprises a PC 8 and a case 11 attached so as to protrude from one end of the light guide plate 10.

The LED 9 is disposed on the TFT glass substrate 4
In the portion not bonded to the CF glass substrate 5, L
It is arranged in the area corresponding to the unconnected part of SI6.

The thickness of each member in this case will be described with reference to FIG. Each of the TFT glass substrate 4 and the CF glass substrate 5 is 0.7 mm, and the light guide plate 10 is 0.9 mm.
mm, LED9 is 1.0 mm, F to which LED9 is connected
The PC 8, the liquid crystal driving power supply and the FPC 7 for inputting signals are each 0.2 mm, and the case 11 is 0.25 mm. The distance between the CF glass substrate 5 and the light guide plate 10 is 0.1 mm.
Space is arranged. This is the CF glass substrate 5
When the light guide plate 10 and the light guide plate 10 are arranged without any gap, the difference in the refractive index of light is almost eliminated at the boundary, and most of the light passes through without being reflected. Therefore, a space is provided between the CF glass substrate 5 and the light guide plate 10 and, due to the presence of the air layer,
A difference in refractive index is generated at the boundary between the light guide plate 10 and the air layer, so that light incident inside the light guide plate 10 can travel while being reflected.

Therefore, the total thickness of the LED 9 and the FPC 8 is 1.2 mm, and the total thickness of the CF glass substrate 5 and the light guide plate 10 is 1.7 mm. Therefore, LE
The arrangement is such that the thickness of D9 and FPC8 does not affect the overall thickness. The total thickness of the reflective liquid crystal display device 1 is determined by the TFT glass substrate 4, the CF glass substrate 5, the light guide plate 1, and the like.
0, the total thickness of the case 11 is about 2.65 mm.

By arranging the LEDs 9 as described above, it is possible to reduce factors affecting the overall thickness of the reflective liquid crystal display device 1. Furthermore, the reflection type liquid crystal display device 1 can be downsized by narrowing the frame of the entire device.

Next, a design method when determining the positions of the light guide plate 10 and the LED 9 will be described.

As shown in FIG. 3B, the LED 9 is inserted into a square hole provided in the case 11,
It has a fixed structure.

As shown in FIG. 4, the predetermined distance D, which is the distance between the LED 9 and the light guide plate 10 such that the light emitted from the LED 9 can efficiently and efficiently enter the light guide plate 10, is given by the following equation. Decided.

The thickness of the light guide plate 10 is E, the outgoing angle of the light emitted from the LED 9 out of the LED 9 and entering the incident surface of the light guide plate 10 and effective for illumination is θ, and the incident surface of the light guide plate 10 is
Assuming that a predetermined distance from the emission surface of No. 9 is D, D = (E / 2) / tan (θ / 2).

In the case of the front light illumination device 3 shown in FIG. 2, the thickness E of the light guide plate 10 is 0.9 mm. The light emission angle θ effective for illumination is 114 °. this is,
This is because, as shown in FIG. 5, of the light emitted from the LED 9, the light can enter the light guide plate 10 and travel while reflecting within the light guide plate 10, and the range of light contributing to illumination is 114 °.

Further, the emission angle θ of light effective for illumination will be described in detail with reference to FIG. First, the refractive index n _{1 of} air is set to 1.0, and the refractive index n ₂ of the light guide plate 10 is set to 1.3.
Considering the above, if the refraction angle when light is emitted from the light guide plate 10 is θ ₁ and the emission angle is θ ₂ , sin θ ₁ / sin θ ₂ = n ₂ / n ₁ = 1.3 is established according to Snell's law. . Further, the condition when light is emitted from the light guide plate 10 is sin θ ₁ ≦ 1. Therefore, sin θ ₂ ≦ sin θ ₁ /1.3=1/1.3=0.7
Therefore, θ ₂ ≦ 50 °. Therefore, θ ₂ > 50
At °, the light reflects inside the light guide plate 10. When the refraction angle when light enters the light guide plate 10 is θ ₃ , θ
It can be said that light is reflected inside the light guide plate 10 when ₃ > 40 °. Further, assuming that the incident angle when light is incident on the light guide plate 10 is θ ₄ , sin θ ₄ / sin θ ₃ = n ₂ / n ₁ = 1.3 is satisfied according to Snell's law. Substituting θ ₃ = 40 ° into this, the calculation results in θ ₄ ≒ 57 °. The angle θ is θ = 2θ ₄
≒ 114 °. Therefore, of the light emitted from the LED 9, the emission angle θ of the light that is reflected in the light guide plate 10 and effective for illumination is 114 °.

Therefore, D = (E / 2) / tan (θ
/ 2), when the thickness E of the light guide plate 10 is 0.9 mm and the angle θ of the light range is 114 °, the predetermined interval D is about 0.3.
mm.

Next, specific means of a positioning portion for fixing the light guide plate 10 and the LED 9 at a suitable position will be described.

The light guide plate 10 as shown in FIGS.
By forming the case 11 and the shape as shown in FIGS. 1A to 1E, the following effects can be obtained.

First, as shown in FIG.
In the case 11 for housing the LED 9 and the light guide plate 10 provided on the upper side, 0.1 mm is set so as to be smaller than the thickness of the light guide plate 10.
It is possible to provide a step 12 as a step of about 0.2 mm.

As a result, the step 12 and the light guide plate 10 are engaged with each other, so that the light guide plate 10 and the LED 9 can be kept at a certain distance or more. Therefore, it is possible to prevent a portion near the LED 9 from being illuminated and becoming dark on the display screen.

As shown in FIG. 1B, the light guide plate 1
It is possible to provide a projection 13 as a positioning part having a height of 0.3 mm at 0. Thus, when the light guide plate 10 is assembled into the case 11, the protrusion 13 contacts the end of the case 11. That is, the distance between the light guide plate 10 and the LED 9 can be maintained at a certain distance or more. Therefore, it is possible to prevent a portion of the display screen near the LED 9 from being darkened without being illuminated. This means can be an effective means when it is difficult to form a step in the case 11.

Further, as shown in FIG. 1C, the light guide plate 10 is provided with a convex portion 14 as a positioning portion having a height of 0.2 mm, and the case 11 is provided with a depth so as to be fitted with the convex portion 14. It is possible to provide a concave portion 15 as a positioning portion having a thickness of 0.2 mm.

Thus, it is possible to prevent the light guide plate 10 from moving out of the case 11, that is, in a direction in which the distance between the LED 9 and the light incident surface of the light guide plate 10 is increased.
The light guide plate 10 and the LED 9 can keep a distance within a certain range. Therefore, it is possible to prevent a situation in which a part of the light emitted from the LED 9 does not enter the light guide plate 10.

Further, the height of the case 11 is set to be inward of the case 11 so as not to affect the light emitted from the LED 9.
A convex portion 16 as a positioning portion of about 2 mm is provided.
This can prevent the LED 9 from tilting forward,
The light emitted from the LED 9 is normally directed to the incident surface of the light guide plate 10.

Further, since the light guide plate 10 is fixed at a position separated by a predetermined distance D, which is a suitable distance from the LED 9, a necessary and sufficient amount of light can be supplied to the light guide plate 10. Therefore, a liquid crystal display device free from brightness and display unevenness can be manufactured.

Further, as shown in FIG.
0 is provided with a concave portion 17 as a positioning portion having a depth of 0.1 mm, and the case 11 is provided with a convex portion 18 as a positioning portion having a height of 0.1 mm inward so as to engage with the concave portion 17. It is possible to provide.

Thus, it is possible to prevent the light guide plate 10 from moving out of the case 11, that is, the direction in which the distance between the LED 9 and the light incident surface of the light guide plate 10 is increased. Within the distance. Therefore, it is possible to prevent a phenomenon that a part of the light emitted from the LED 9 does not enter the light guide plate 10. Further, in the case 11, no projection is provided on the outside, which can contribute to a reduction in the thickness of the device.

Further, in the case 11, a hole for inserting the LED 9 is provided above the LED 9.

Thus, the upper part of the LED 9 and the case 11
To prevent the LED 9 from tilting forward, so that the light emitted from the LED 9 normally goes to the incident surface of the light guide plate 10.

Further, since the light guide plate 10 is fixed at a position separated from the LED 9 by a predetermined distance D which is a suitable distance, a necessary and sufficient amount of light can be supplied to the light guide plate 10. Therefore, a liquid crystal display device free from brightness and display unevenness can be manufactured.

Further, as shown in FIG. 1 (e), at the portion of the case 11 where the LED 9 is inserted, the distance between the LED 9 and the plane parallel to the exit surface of the LED 9 and the entrance surface of the light guide plate 10 is optimal. It is possible to provide a bent portion 19 as a positioning portion. Further, in this case, L
A hole is provided in the bent portion 19 so as not to hinder the light emitted from the ED 9. The light guide plate 10 has a depth of 0.1 mm.
The case 11 is provided with a convex portion 18 having a height of 0.1 mm inward so as to engage with the concave portion 17.

Thus, the LED 19 is bent by the bent portion 19.
The position of 9 is fixed. Further, the position of the light guide plate 10 is fixed by the engagement between the concave portion 17 and the convex portion 18. Therefore, it is possible to position the incident surface of the light guide plate 10 and the emission surface of the LED 9.

Further, since the light guide plate 10 is fixed at a position separated from the LED 9 by a predetermined distance D which is a suitable distance, a necessary and sufficient amount of light can be supplied to the light guide plate 10. Therefore, a liquid crystal display device free from brightness and display unevenness can be manufactured.

Note that there is an effect that variations in each component such as the thickness of the case 11 do not affect the distance between the light guide plate 10 and the LED 9.

Further, in the present embodiment, the front light illuminating device 3 has been described, but a backlight illuminating device may be used. Further, in the present embodiment, the LED 9 is used as a light source, but the LED 9 need not be the one that can irradiate the light guide plate 10.

Further, in this embodiment, the reflection type liquid crystal display element has been described, but the transmission type liquid crystal display element may be used. That is, the present invention can be applied not only to the front light type but also to the backlight type liquid crystal display device.
This is more suitable for a front-light type liquid crystal display device that requires more precise control of the positional relationship between the ED 9 and the light guide plate 10.

As described above, in the reflection type liquid crystal display device 1 of the present embodiment, a predetermined distance is provided between the LED 9 and the side surface of the light guide plate 10, and the LED 9 and the light guide plate 10 are separated by the case 11. Fixed. That is, for example,
After attaching the LED 9 to the case 11 and fixing it, the light guide plate 1
In order to attach and fix 0 to the case 11, it is only necessary to set the light guide plate 10 on the positioning portion of the case 11.

As a result, the distance between the LED 9 and the side surface of the light guide plate 10 via the case 11 becomes constant.
0, the amount of light incident on the reflective liquid crystal display device 1 becomes constant.
This has no adverse effect on brightness and display unevenness.

Further, in the present embodiment, the LED 9 is formed only by forming the positioning portion on the case 11 or the light guide plate 10.
Since the distance between the light guide plate 10 and the side surface of the light guide plate 10 can be maintained at a predetermined interval, the light guide plate 10 is not subjected to complicated processing.

Therefore, in order to prevent adverse effects on brightness and display unevenness, the light guide plate 10 must be
It is possible to provide the reflective liquid crystal display device 1 that can easily optimize the distance between the LED and the LED 9 and avoid an increase in manufacturing cost.

In the reflection type liquid crystal display device 1 of the present embodiment, since the light guide plate 10 is fixed inside the case 11, the LED 9 and the light guide plate 10 are housed in the same case 11. Therefore, the LED 9 and the light guide plate 10 can be easily and precisely arranged at optimized positions, and the front light illumination device 3 and the reflection type liquid crystal display element 2 can be integrated.

As a result, the amount of light incident on the light guide plate 10 becomes constant, and the reflection type liquid crystal display device 1 which does not adversely affect brightness and display unevenness can be provided.

Further, in the reflection type liquid crystal display device 1 of the present embodiment, it is possible to prevent the light guide plate 10 from moving in the direction approaching the LED 9 and the direction coming out of the case 11. Therefore, a certain distance can be maintained between the LED 9 and the light guide plate 10 with a specific and simple configuration, and an increase in manufacturing cost can be prevented.

In the reflective liquid crystal display device 1 and the method of manufacturing the same according to the present embodiment, the predetermined distance D between the LED 9 and the side surface of the light guide plate 10 is such that the thickness of the light guide plate 10 is E, the LED 9
When the emission angle of the light that enters the side surface of the light guide plate 10 out of the light emitted from and is effective for illumination is θ, D = (E /
2) Determined by / tan (θ / 2).

With the above configuration, it is possible to determine the optimum distance between the LED 9 and the side surface of the light guide plate 10 such that a necessary and sufficient amount of light enters the light guide plate 10. Further, the optimum distance between the LED 9 and the side surface of the light guide plate 10 can be obtained from the type of the light source and the thickness of the side surface of the light guide plate 10. Therefore, the amount of light incident on the light guide plate 10 is optimal and constant regardless of the type of light source.

Thus, it is possible to provide a method of manufacturing the reflective liquid crystal display device 1 which does not adversely affect brightness and display unevenness. In addition, there is an effect that the variation in the thickness of each member other than the light guide plate 10 does not affect the predetermined distance D between the side surface of the light guide plate 10 and the LED 9.

Further, in the method of manufacturing the reflection type liquid crystal display device 1 of the present embodiment, even if the light guide plate 10 is attached to the case 11 after the LEDs 9 are arranged in the case 11 in advance, the LED 9 and the light guide plate 10 Is constant without any deviation. Therefore, the amount of light incident on the light guide plate 10 is also constant, and does not adversely affect brightness and display unevenness.

As a result, the distance between the light guide plate 10 and the LED 9 can be easily optimized at the time of manufacturing so as not to adversely affect the brightness and the display unevenness, and an increase in manufacturing cost can be avoided. A method for manufacturing the reflection type liquid crystal display device 1 can be provided.

In the method of manufacturing the reflection type liquid crystal display device 1 according to the present embodiment, the light guide plate 10 is inserted into the case 11 and guided to the positioning portion.

According to the above method, the light guide plate 10 is
, The LED 9 and the light guide plate 10 are housed in the same case 11. Therefore,
By arranging the LED 9 and the light guide plate 10 at positions optimized with high precision, the front light illuminating device 3 and the reflective liquid crystal display element 2 can be integrated. This makes it possible to provide a method of manufacturing the reflective liquid crystal display device 1 in which the amount of light incident on the light guide plate 10 is also constant and does not adversely affect brightness and display unevenness.

Further, the reflection type liquid crystal display device 1 of the present embodiment guides at least one or more LEDs 9 and an incident surface on which light from the LEDs 9 is incident, and emits the guided light. A front light illuminating device 3 comprising a light guide plate 10 having a surface, a TFT glass substrate 4 and a CF
The glass substrate 5 is composed of two glass substrates, and one of the glass substrates is smaller than the other glass substrate for inputting a signal. The light emitted from the light guide plate 10 is controlled for each pixel so that an image is formed. In the reflection type liquid crystal display element 2 displaying the LED, the LED 9 is arranged without protruding outside an area corresponding to a portion where one glass substrate of the reflection type liquid crystal display element 2 is small when viewed from the image display side. It may be.

The reflection type liquid crystal display device 1 of the present embodiment is
LED 9, light guide plate 10, and case 1 for holding these
1, a reflection type liquid crystal display element 2. By arranging the LED 9 on the area of the reflective liquid crystal display element 2, the frame can be narrowed, and as described above, one of the glass substrates is out of the area corresponding to the portion smaller than the other glass substrate. The reflection type liquid crystal display device 1 which is thinned by being arranged without protruding, and is reduced in size and weight
Can be realized.

[0097]

As described above, the liquid crystal display device of the present invention is provided with a case for fixing the light source and the light guide plate in a fixed state, and the case or the light guide plate is provided with a predetermined distance between the light source and the side surface of the light guide plate. A positioning portion for maintaining the interval is formed.

Therefore, the distance between the light source and the side surface of the light guide plate can be maintained at a predetermined distance only by forming the positioning portion on the case or the light guide plate. As a result, the distance between the light source and the side surface of the light guide plate via the case is constant without performing complicated processing on the light guide plate, so that the amount of light incident on the light guide plate is also constant, and the brightness of the liquid crystal display device is increased. Further, it is possible to prevent the display unevenness from being adversely affected.

Therefore, the distance between the light guide plate and the light source can be easily optimized at the time of manufacture so as not to adversely affect the brightness and display unevenness, so that an increase in manufacturing cost can be avoided. Play.

Further, in the liquid crystal display device of the present invention, in the above configuration, the light guide plate is guided to the positioning portion by being inserted into the case.

Therefore, the light source and the light guide plate can be easily and precisely arranged at optimized positions, and the illuminating means and the liquid crystal display element can be integrated, so that the amount of light incident on the light guide plate is also constant. This has the effect of not adversely affecting brightness and display unevenness.

Further, in the liquid crystal display device of the present invention, in the above-mentioned configuration, the positioning portion may be a concave portion formed on one of the case and the light guide plate and a convex portion formed on the other to be fitted into the concave portion. The light guide plate or the case has a step formed on the case so as to abut on either the end portion or the end portion of the light guide plate.

Therefore, the specific distance between the light source and the light guide plate can be maintained with a specific and simple configuration, so that an increase in manufacturing cost can be prevented.

In the liquid crystal display device according to the present invention, the predetermined distance D between the light source and the side surface of the light guide plate is such that the thickness of the light guide plate is E, and the side surface of the light guide plate out of the light emitted from the light source is provided. And when the emission angle of light effective for illumination is θ, it is determined by D = (E / 2) / tan (θ / 2).

Therefore, the optimum distance between the light source and the side surface of the light guide plate can be determined from the type of the light source and the thickness of the side surface of the light guide plate. Even if the type is used, the effect is obtained that the amount is optimal and constant.

As described above, according to the method of manufacturing the liquid crystal display device of the present invention, the light guide plate is fixed to the case after fixing the light source to the case, and the light guide plate is fixed to the case after fixing the light source to the case. When mounting in a state, a predetermined distance between the light source and the light guide plate is maintained by a positioning portion formed on the case or the light guide plate.

Therefore, since the distance between the light source and the side surface of the light guide plate is constant without any deviation, the amount of light incident on the light guide plate is also constant, and there is an effect that the brightness and display unevenness are not adversely affected.

Further, in order to prevent the brightness and display unevenness from being adversely affected, it is possible to easily optimize the distance between the light guide plate and the light source during manufacturing, thereby avoiding an increase in manufacturing cost. To play.

Further, the method of manufacturing a liquid crystal display device according to the present invention is a method in which, in the above method, the light guide plate is inserted into the case to guide it to the positioning portion.

Therefore, since the light source and the light guide plate can be arranged at precisely optimized positions and the illuminating means and the liquid crystal display element can be integrated, the amount of light incident on the light guide plate becomes constant and the brightness increases. This has the effect of not adversely affecting display and display unevenness.

Further, in the method of manufacturing a liquid crystal display device according to the present invention, in the above method, the thickness of the light guide plate is set to E, and the light emitted from the light source enters the side surface of the light guide plate, and the light effective for illumination is obtained. When the emission angle is θ, the predetermined distance D between the light source and the light guide plate is determined by D = (E / 2) / tan (θ / 2).

Therefore, since the optimum distance between the light source and the side surface of the light guide plate can be determined, the amount of light incident on the light guide plate is optimum and constant regardless of the type of light source used. It works.

[Brief description of the drawings]

FIGS. 1A to 1E are cross-sectional views of a lighting device used in a reflective liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing the entire configuration of the reflective liquid crystal display device.

FIG. 3A is a cross-sectional view illustrating an arrangement portion of a light source in the reflective liquid crystal display device, and FIG. 3B is an exploded perspective view illustrating an arrangement portion of the light source in the reflective liquid crystal display device. .

FIG. 4 is an explanatory diagram showing a positional relationship between a light source and a light guide plate in the reflective liquid crystal display device.

FIG. 5 is an explanatory diagram showing directivity characteristics of light of an LED as a light source.

FIG. 6 is an explanatory diagram showing a range of light contributing to illumination among light incident on the light guide plate of the reflective liquid crystal display device according to the embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a lighting device in a conventional reflective liquid crystal display device, showing how light from a light source is incident on a glass substrate.

FIG. 8 is a cross-sectional view showing a lighting device in a conventional reflective liquid crystal display device, showing a state in which light from a light source enters a liquid crystal layer without passing through a deflecting plate.

FIG. 9 is an exploded perspective view showing the overall configuration of a lighting device in another conventional reflective liquid crystal display device.

FIGS. 10 (a), (b) and (c) are explanatory views showing a positional relationship between a light source and a light guide plate in the above-mentioned conventional reflection type liquid crystal display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Reflection type liquid crystal display device (liquid crystal display device) 2 Reflection type liquid crystal display device (liquid crystal display device) 3 Front light illumination device (illumination means) 4 TFT glass substrate 5 CF glass substrate 6 Liquid crystal drive driver LSI 7 FPC 8 FPC 9 LED (light source) 10 light guide plate 11 case 12 step (step portion) 13 protrusion (positioning portion) 14 convex portion (positioning portion) 15 concave portion (positioning portion) 16 convex portion (positioning portion) 17 concave portion (positioning portion) 18 convex Portion (positioning portion) 19 Bending portion (positioning portion) D Predetermined interval E Thickness of light guide plate θ Emission angle of light effective for illumination θ Refraction angle when ₁ light is emitted from light guide plate θ ₂ light from light guide plate Emission angle when emitting θ ₃ Refraction angle when light enters the light guide plate θ ₄ Incident angle when light enters the light guide plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H091 FA23Z FA45Z FD05 FD12 FD22 LA12 LA18 5G435 AA17 BB12 BB16 EE22 FF08 GG23 GG26 KK03

Claims (7)

[Claims] An illumination device comprising: a liquid crystal display element for displaying an image; at least one or more light sources; and a light guide plate for emitting light from the light source from a side surface and emitting light to the liquid crystal display element. In the liquid crystal display device provided, a case is provided for fixing the light source and the light guide plate in a fixed state, and the case or the light guide plate has a positioning portion for maintaining a predetermined distance between the light source and the side surface of the light guide plate. A liquid crystal display device characterized by being formed. 2. The liquid crystal display device according to claim 1, wherein the light guide plate is guided to a positioning portion by being inserted into the case. 3. The positioning portion is in contact with a concave portion formed on one of the case and the light guide plate and a convex portion formed on the other to fit into the concave portion, or on one of the case end and the light guide plate end. 3. The liquid crystal display device according to claim 1, wherein the liquid crystal display device comprises a step portion formed on the light guide plate or the case as much as possible. 4. The predetermined distance D between the light source and the side surface of the light guide plate is such that the thickness of the light guide plate is E, and outgoing light from the light source enters the side surface of the light guide plate and determines the emission angle of light effective for illumination. 4. The liquid crystal display device according to claim 1, wherein the angle θ is determined by D = (E / 2) / tan (θ / 2). 5. 5. A liquid crystal display element for displaying an image, at least one or more light sources, and illuminating means having a light guide plate for allowing light from the light source to enter the side surface and emitting light to the liquid crystal display element. In the method of manufacturing a liquid crystal display device provided with: while fixing the light guide plate to the case after fixing the light source to the case, while fixing the light guide plate to the case after fixing the light source to the case, A method for manufacturing a liquid crystal display device, wherein a predetermined distance between the light source and the light guide plate is maintained by a positioning portion formed on the case or the light guide plate. 6. The method for manufacturing a liquid crystal display device according to claim 5, wherein the light guide plate is inserted into the case to guide the light guide plate to the positioning portion. 7. A predetermined distance between the light source and the light guide plate, where E is a thickness of the light guide plate, and θ is an emission angle of light which enters a side surface of the light guide plate out of light emitted from the light source and is effective for illumination. 7. The method according to claim 5, wherein D is determined by the following equation: D = (E / 2) / tan (θ / 2).