JPH11249130A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display(LCD) device with which the display of high and uniform lightness can be provided even when it is dark around the device. SOLUTION: This LCD device is constituted by charging liquid crystals 8 between a TFT substrate 1, which is provided with a display electrode 7 composed of reflection materials, TFT for driving the liquid crystals 8 by connecting this display electrode 7 and EL elements 10, 11 and 12, and a counter substrate 16 opposed with this TFT substrate 1 and concerning this LCD device, the display electrode 7 is provided with a light transmission hole 9 for supplying the emitted light of the EL element to the liquid crystals 8. Concerning the organic EL element, a hole injected from an anode and an electron injected from a cathode are coupled again inside a light emitting layer, and an exciter is generated by exciting an organic molecule forming the light emitting layer. Light is emitted from the light emitting layer in a process for this exciter to make a radiation inactive, and this light 19 is discharged from the anode to the light transmission hole 9 provided on the display electrode 7. Even when it is dark around the device, the organic EL element provided on the lower layer of each display electrode is emitted as a light source, the indication of high and uniform lightness can be observed over all the surface of the LCD device.

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 provided with an electroluminescence (ElectroLuminescence: hereinafter referred to as "EL") element as a light source.

[0002]

2. Description of the Related Art Heretofore, there has been proposed a so-called reflection type liquid crystal display device for displaying a display by reflecting light incident from an observation direction. However, the reflective liquid crystal display device has a problem that it is extremely difficult to see a bright display in a dark place.

Therefore, as a solution to this problem, a structure as shown in FIG. 4 has been proposed. FIG. 4 shows a sectional view of a conventional reflection type liquid crystal display device. As shown in FIG. 1, a conventional reflective liquid crystal display device includes a liquid crystal display panel 120, a reflector 130, a white light source 140, a light guide plate 150, and a light collector 1
Consists of 60. The liquid crystal display panel 120 is formed of a glass substrate or the like, and includes a thin film transistor (Thin Film Transistor).
or: Hereinafter, referred to as “TFT”. ), And a counter substrate 110 made of a glass substrate or the like and facing the TFT substrate.

On one side of the liquid crystal display panel 120, there is provided a reflector 130 having a reflection surface, and on the other side, a white light source 140 is arranged in parallel with one side of the liquid crystal display panel 120, and the light source is provided. A light guide plate 150 and a light collector 160 for guiding the light of 140 to the entire surface of the liquid crystal display panel 120 are provided. Light 170 emitted from a white light source 140
Is transmitted through the light guide plate 150 and the liquid crystal display panel 120, is reflected by the reflection plate 130, passes through the liquid crystal display panel 120 again, and further passes through the light guide plate 150. By doing so, the display of the liquid crystal display device enters the eyes 190 of the observer.

[0005]

However, the white light source 14
A part 180 of the light emitted from 0 passes through the light guide plate 150, is reflected on the surface of the liquid crystal display panel 120, passes through the light guide plate 150 again, and enters the eye 190. At this time the eye 190
Together with the light 180 of the white light source 140,
The image of 0 is reflected and enters. Therefore, the display to be observed is the light source 1 provided on one side of the liquid crystal display panel 120.
The area around 40 appeared particularly white, and a normal display could not be obtained on the liquid crystal display device.

The present invention has been made in view of the above-mentioned conventional disadvantages, and it is an object of the present invention to provide a liquid crystal display device capable of obtaining a bright and uniform brightness display even when the surroundings are dark. .

[0007]

According to the present invention, there is provided a liquid crystal display device comprising: a first substrate having a thin film transistor connected to a display electrode made of a reflective material and driving a liquid crystal; and a first substrate having an electroluminescent element. A second transparent substrate facing the substrate, wherein liquid crystal is filled between the two substrates, and light emitted from the electroluminescence element is supplied to the liquid crystal through a light guide hole provided in the display electrode. It is.

Further, in the liquid crystal display device of the present invention, the EL element is provided in a region other than the display electrode. Further, in the liquid crystal display device of the present invention, the EL element is provided at the position where the light shielding portion is disposed. Further, in the liquid crystal display device of the present invention, a substrate provided with an EL element is provided so as to face a TFT substrate,
A light guide hole through which light emitted from the L element passes is provided in the display electrode.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> A liquid crystal display of the present invention will be described below. FIG. 1 is a cross-sectional view showing one pixel of a liquid crystal display device including the organic EL element according to the first embodiment as a light source.

A gate electrode 2 is formed on an insulating substrate 1 made of glass or the like, and an active layer 4 made of polysilicon is formed via an insulating film 3 provided on the gate electrode 2. The active layer 4 is provided with a source region 4s and a drain region 4d into which impurities are implanted. An interlayer insulating film 5 is formed thereon, and one source region 4s is provided with a display electrode (source) made of a reflective material, for example, a metal such as Al through a contact hole 6 formed in the interlayer insulating film 5. Electrode) 7
Is connected to The other drain region 4d is connected to a drain electrode 7d via a contact hole 6 formed in the interlayer insulating film 5. Thus, the insulating substrate 1 on which the TFT is formed, that is, the TFT substrate 1 is completed. The display electrode 7 is provided with a light guide hole 9 which is a light guide hole.

As shown in FIG. 1, an organic EL element is a TFT.
A cathode 10 made of a magnesium-indium alloy (MgIn) and a MTDATA (4,4'-b) are provided on the TFT substrate 1 on which a light guide hole 9 provided in the display electrode 7 is formed.
The second hole transport layer composed of is (3-methylphenylphenylamino) biphenyl), TPD (4,4 ', 4 "-tris (3-methylpheny
1 hole transport layer composed of lphenylamino) triphenylanine, Be containing quinacridone derivative
a light emitting element layer 11 made of an organic compound of each of a light emitting layer made of bq2 (10-benzo [h] quinolinol-beryllium complex) and an electron transport layer made of Bebq2;
An anode 12 made of a transparent electrode such as dium thin oxide is laminated in this order. As described above, the anode 12, the cathode 10, and the light emitting element layer 11 constitute an organic EL element. The hole transport layer may be a single layer.

After forming the TFT and the organic EL element, a flattening film 8 is formed on the entire surface. Organic EL elements
The holes injected from the anode and the electrons injected from the cathode recombine inside the light emitting layer, and excite the organic molecules forming the light emitting layer to generate excitons. Light is emitted from the light emitting layer during the process of radiation deactivation of the excitons, and this light 19 is emitted from the anode to the light guide hole 9 provided in the display electrode 7 (in the direction of arrow 19 in the figure).

As a result, the emitted light 19 passes through the light guide hole 9 provided in the display electrode 7 and passes through the liquid crystal layer 13,
Further, the light enters the observer's eyes 190 through the transparent counter substrate 16 provided with the insulating film 14 and the common electrode 15. Therefore, even when the periphery is dark, the organic EL element provided below each display electrode emits light to serve as a light source, so that bright and uniform brightness display can be observed on the entire surface of the liquid crystal display device.

The number or size of the light guide holes 9 may be determined according to the brightness required for observing the display. <Second Embodiment> FIG. 2 shows an organic EL device according to the second embodiment.
FIG. 4 is a cross-sectional view illustrating one pixel of a liquid crystal display device including an element as an auxiliary light source.

As shown in FIG. 1, the difference from the liquid crystal display device of FIG. 1 is that the organic EL element is provided on the side of the opposing substrate 16 where the light-shielding portion 18 disposed in the area other than the display electrode 7 is provided. And the display electrode 7 is not provided with the light guide hole 9. Since the structure of the TFT is the same as that of the first embodiment, the description of the structure of the TFT substrate 1 is omitted.

The counter substrate 16 which faces the TFT substrate 1 via the liquid crystal layer 13 will be described. A color filter 17 having a light-shielding portion 18 is formed on a transparent insulating counter substrate 16 at a position corresponding to a TFT forming position on the TFT substrate 1.
Then, a common electrode 15 made of ITO (Indium Tin Oxide) is formed. At this time, the common electrode 1 is provided at a place where the organic EL element is provided so as to be independent of the electrode of the organic EL element.
5 is not formed. By making them independent, even when the surroundings are bright, it is possible to select the organic EL element to emit light when a brighter display is desired.

Next, an organic EL element including the cathode 10, the light emitting element layer 11, and the anode 12 is formed on the light shielding portion 18.
Then, the insulating film 14 is formed so as to cover the color filter 15 (showing a red (R) region in the figure) and the organic EL element. The thus-prepared counter substrate 16 and the TFT substrate 1 are bonded together at their periphery, and a liquid crystal layer 13 is filled between the substrates 1 and 16 to complete a liquid crystal display device.

When observing the display of the liquid crystal display device thus completed, if the surroundings are dark, the organic EL element emits light. Light 19 emitted from the organic EL element is emitted toward the TFT substrate 1 and reflected by the display electrode 7,
Thereafter, the liquid crystal layer 13, the color filter 17, and the opposing substrate 1
Emit through 6.

Since the organic EL element is formed at a position corresponding to the light shielding portion 18, the emitted light is directly transmitted to the eyes 19 of the observer.
It never goes to zero. In addition, since the organic EL element is formed in the light-shielding portion arranged in a region other than each display electrode of the liquid crystal display panel, bright and uniform brightness display can be observed on the entire surface of the liquid crystal display panel.

In this embodiment, the light shielding unit 1 is used.
8 is provided on the color filter 17, but the color filter 1
In the case where 7 is not provided, the light shielding portion 18 may be provided on the counter substrate 16 with black resin or the like. <Third Embodiment> FIG. 3 shows an organic EL device according to the third embodiment.
FIG. 4 is a cross-sectional view illustrating one pixel of a liquid crystal display device including an element as an auxiliary light source.

As shown in the figure, the difference from the liquid crystal display of FIG. 1 is that the organic EL element is provided on an organic EL element substrate 20 which is an insulating substrate different from the TFT substrate 1 and the counter substrate 16. It is a point that is. Organic EL element substrate 20
Has a cathode 10, a light emitting element layer 11 and an anode 12
Are sequentially stacked, and an insulating film 21 is formed thereon.
Is formed, and the organic EL element is a TFT substrate 1
It is arranged at a position corresponding to the light guide hole 9 provided in the upper display electrode 7.

The light 19 emitted from the organic EL element is
The light passes through the light guide hole 9 provided in the display electrode 7 on the FT substrate 1 and further passes through the counter substrate 16. Therefore, when observing the display when the periphery of the liquid crystal display device is dark, the organic EL
The element emits light. Then, the emitted light 19 passes through the light guide hole 9 provided in the display electrode 7 and the liquid crystal 8 and the counter substrate 1.
Since the light exits through 6 and enters the eye 190, a bright display can be observed. Further, since the organic EL elements are provided corresponding to the respective display electrodes 7 of the liquid crystal display device, a display with uniform brightness can be obtained on the entire surface of the liquid crystal display device. In addition, since the organic EL element substrate 20 is formed by forming only the organic EL element, the organic EL element substrate 20 has an advantage that the organic EL element substrate can be replaced in the event of any failure.

The organic EL element substrate 20 can be formed separately from the liquid crystal display device comprising the other substrates 1 and 16,
The insulating film 21 can be bonded to the surface of the insulating film 21 using a transparent adhesive, but may be selected as needed. The number or size of the light guide holes 9 provided in the display electrodes 7 may be determined in accordance with the required brightness as in the first embodiment.

[0024]

According to the liquid crystal display device of the present invention, it is possible to obtain a liquid crystal display device which can display bright and uniform brightness even when the surroundings are dark.

[Brief description of the drawings]

FIG. 1 is a sectional view of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 TFT substrate 7 Display electrode 9 Light guide hole 10 Cathode 11 Light emitting element layer 12 Anode 16 Counter substrate 18 Shielding part 20 Organic EL element substrate

Claims (4)

[Claims] A first substrate provided with a display electrode made of a reflective material, a thin film transistor connected to the display electrode for driving liquid crystal, and an electroluminescence element; and a second transparent substrate facing the first substrate. Wherein the liquid crystal is filled between the two substrates, and light emitted from the electroluminescence element is supplied to the liquid crystal through a light guide hole provided in the display electrode. apparatus. 2. A display device comprising: a display electrode made of a reflective material; a first substrate provided with a thin film transistor connected to the display electrode and driving a liquid crystal; and a second transparent substrate facing the first substrate. A liquid crystal display device characterized by being filled with the liquid crystal between both substrates, wherein the second transparent substrate includes an electroluminescent element in a region other than the display electrode. 3. A display device comprising: a display electrode made of a reflective material; a first substrate having a thin film transistor connected to the display electrode and driving a liquid crystal; and a second transparent substrate facing the first substrate; What is claimed is: 1. A liquid crystal display device comprising a liquid crystal filled between two substrates, wherein a light-shielding portion is disposed on a side of the second substrate facing the first substrate, and an electro-optical device is provided at a position where the light-shielding portion is disposed. A liquid crystal display device provided with a luminescence element. 4. A display apparatus comprising: a display electrode made of a reflective material; a first transparent substrate having a thin film transistor connected to the display electrode and driving a liquid crystal; and a second transparent substrate facing the first transparent substrate. A liquid crystal display device having the liquid crystal filled between the two substrates, wherein a third substrate provided with an electroluminescent element is provided facing the first transparent substrate, and the light emission of the electroluminescent element is provided. A liquid crystal display device, wherein light is supplied to the liquid crystal through a light guide hole provided in the display electrode.