JP4446500B2 - Liquid crystal display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device provided with an electroluminescence (hereinafter referred to as “EL”) element as a light source.
[0002]
[Prior art]
Conventionally, a so-called reflection type liquid crystal display device has been proposed in which light incident from an observation direction is reflected to display a display.
However, the reflective liquid crystal display device has a problem that it is very difficult to see a bright display in a dark place.
[0003]
Therefore, a structure as shown in FIG. 4 has been proposed as a solution to this problem.
FIG. 4 shows a cross-sectional view of a conventional reflective liquid crystal display device.
As shown in the drawing, the 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 160.
The liquid crystal display panel 120 includes a TFT substrate 100 made of a glass substrate or the like and provided with a thin film transistor (hereinafter referred to as “TFT”), and a counter substrate 110 also made of a glass substrate or the like and facing the TFT substrate. Become.
[0004]
A reflective plate 130 having a reflective surface is provided on one side of the liquid crystal display panel 120, and a white light source 140 is disposed in parallel to one side of the liquid crystal display panel 120 on the other side. A light guide plate 150 and a light collector 160 that guide the light to the entire surface of the liquid crystal display panel 120 are disposed.
The light 170 emitted from the white light source 140 passes 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]
[Problems to be solved by the invention]
However, a part of the light 180 emitted from the white light source 140 passes through the light guide plate 150, is reflected by the surface of the liquid crystal display panel 120, and passes through the light guide plate 150 again to enter the eye 190. At this time, the image of the white light source 140 is reflected and enters the eye 190 together with the light 180 of the white light source 140. For this reason, the observed display is that the vicinity of the light source 140 provided on one side of the liquid crystal display panel 120 looks particularly white, and a normal display cannot be obtained in the liquid crystal display device.
[0006]
Therefore, the present invention has been made in view of the above-described conventional drawbacks, and an object of the present invention is to provide a liquid crystal display device which can display bright and uniform brightness even when the surroundings are dark.
[0007]
[Means for Solving the Problems]
The liquid crystal display device of the present invention, the display electrode made of reflective material, a thin film transistor display electrodes to drive the liquid crystal is connected, a first substrate having an electroluminescent element, a second opposed to the first substrate A transparent substrate, filled with the liquid crystal between both substrates, the electroluminescent element is laminated between the display electrode and the first substrate, and the light emitted from the electroluminescent element is provided on the display electrode The liquid crystal is supplied to the liquid crystal through the light guide hole.
[0008]
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 light shielding portion arrangement portion.
Furthermore, in the liquid crystal display device of the present invention, a substrate provided with an EL element is provided opposite to the TFT substrate, and a light guide hole through which light emitted from the EL element passes is provided in the display electrode.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
<First Embodiment>
The liquid crystal display device of the present invention will be described below.
FIG. 1 is a cross-sectional view illustrating one pixel of a liquid crystal display device including the organic EL element according to the first embodiment as a light source.
[0010]
A gate electrode 2 is formed on an insulating substrate 1 such as glass, and an active layer 4 made of polycrystalline silicon is formed through 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 connected to a display electrode (source) made of a reflective material such as a metal such as Al through a contact hole 6 formed in the interlayer insulating film 5. Electrode) 7. The other drain region 4 d is connected to the drain electrode 7 d through 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 that is a light guide hole.
[0011]
As shown in the figure, the organic EL element has a cathode 10 made of a magnesium-indium alloy (MgIn), MTDATA (at a position corresponding to the light guide hole 9 provided in the display electrode 7 on the TFT substrate 1 on which the TFT is formed. Second hole transport layer composed of 4,4'-bis (3-methylphenylphenylamino) biphenyl), first hole transport layer composed of TPD (4,4 ', 4 "-tris (3-methylphenylphenylamino) triphenylanine), quinacridone ) A light emitting layer made of Bebq2 (10-benzo [h] quinolinol-beryllium complex) containing a derivative, a light emitting element layer 11 made of each organic compound of an electron transport layer made of Bebq2, a transparent electrode such as ITO (Indium Thin Oxide) The organic EL element is composed of the anode 12, the cathode 10, and the light emitting element layer 11. One layer may be sufficient as the transport layer.
[0012]
Then, after forming the TFT and the organic EL element, a planarizing film 8 is formed on the entire surface.
In the organic EL element, holes injected from the anode and electrons injected from the cathode are recombined inside the light emitting layer, and excitons are generated by exciting organic molecules forming the light emitting layer. Light is emitted from the light emitting layer in the process of radiation deactivation of the excitons, and the 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).
[0013]
As a result, the emitted light 19 passes through the light guide hole 9 provided in the display electrode 7, passes through the liquid crystal layer 13, and is observed from the transparent counter substrate 16 having the insulating film 14 and the common electrode 15. Enter the eyes 190 of the person. Therefore, even when the periphery is dark, the organic EL element provided in the lower layer of each display electrode emits light and serves as a light source, whereby a bright and uniform brightness display can be observed on the entire surface of the liquid crystal display device.
[0014]
In addition, what is necessary is just to determine the number or magnitude | size of the light guide hole 9 according to the brightness required for observing a display.
<Second Embodiment>
FIG. 2 is a cross-sectional view showing one pixel of a liquid crystal display device provided with the organic EL element of the present embodiment as an auxiliary light source.
[0015]
As shown in the figure, the difference from the liquid crystal display device of FIG. 1 described above is that the organic EL element is provided on the side of the counter substrate 16 having the light shielding portion 18 arranged in a region other than the display electrode 7. The light guide hole 9 is not provided in the display electrode 7. Since the TFT structure is the same as that of the first embodiment, the description of the structure of the TFT substrate 1 is omitted.
[0016]
The counter substrate 16 facing the TFT substrate 1 through the liquid crystal layer 13 will be described.
On the transparent insulating counter substrate 16, a color filter 17 having a light shielding portion 18 corresponding to the TFT formation position on the TFT substrate 1 is formed. Then, a common electrode 15 made of ITO (Indium Tin Oxide) is formed. In that case, in order to make it independent from the electrode of an organic EL element, the common electrode 15 is not formed in the location which provides an organic EL element. By making it independent, it is possible to select the organic EL element to emit light when it is desired to see a brighter display even when the periphery is bright.
[0017]
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. An insulating film 14 is formed so as to cover the color filter 15 (shown in the red (R) region in the figure) and the organic EL element.
The counter substrate 16 and the TFT substrate 1 thus completed are bonded to each other and the liquid crystal layer 13 is filled between the substrates 1 and 16 to complete the liquid crystal display device.
[0018]
When the display of the liquid crystal display device thus completed is observed, if the periphery is dark, the organic EL element is caused to emit light.
Light 19 emitted from the organic EL element is emitted toward the TFT substrate 1, reflected by the display electrode 7, and then emitted through the liquid crystal layer 13, the color filter 17, and the counter substrate 16.
[0019]
Since the organic EL element is formed at a position corresponding to the light shielding portion 18, the emitted light does not directly enter the eyes 190 of the observer.
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, a bright and uniform brightness display can be observed on the entire surface of the liquid crystal display panel.
[0020]
In the present embodiment, the light shielding portion 18 is provided in the color filter 17, but when the color filter 17 is not provided, the light shielding portion 18 may be provided on the counter substrate 16 with a black resin or the like. .
<Third Embodiment>
FIG. 3 is a cross-sectional view showing one pixel of a liquid crystal display device provided with the organic EL element of the present embodiment as an auxiliary light source.
[0021]
As shown in the figure, the difference from the liquid crystal display device 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. Is a point.
The organic EL element substrate 20 is formed with an organic EL element in which a cathode 10, a light emitting element layer 11, and an anode 12 are laminated in this order, and an insulating film 21 formed thereon. The organic EL element is a TFT. It is arranged at a position corresponding to the light guide hole 9 provided in the display electrode 7 on the substrate 1.
[0022]
The light 19 emitted from the organic EL element passes through the light guide hole 9 provided in the display electrode 7 on the TFT substrate 1 and further passes through the counter substrate 16.
Therefore, when the display is observed when the periphery of the liquid crystal display device is dark, the organic EL element is caused to emit light. Then, the emitted light 19 exits through the liquid crystal 8 and the counter substrate 16 through the light guide hole 9 provided in the display electrode 7 and enters the eye 190, so that a bright display can be observed. Moreover, since the organic EL element is provided corresponding to each display electrode 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 only with the organic EL element, it has an advantage that the organic EL element substrate can be replaced if any failure occurs in the organic EL element.
[0023]
In addition, the organic EL element substrate 20 can be separated from the liquid crystal display device composed of the other substrates 1 and 16, or can be used by being bonded to the surface of the insulating film 21 using a transparent adhesive. The selection may be made as necessary.
Note that the number or size of the light guide holes 9 provided in the display electrode 7 may be determined in accordance with the required brightness as in the first embodiment.
[0024]
【The invention's effect】
According to the liquid crystal display device of the present invention, it is possible to obtain a liquid crystal display device that can display bright and uniform brightness even when the surroundings are dark.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a liquid crystal display device showing a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of a liquid crystal display device showing a second embodiment of the present invention.
FIG. 3 is a cross-sectional view of a liquid crystal display device showing a third embodiment of the present invention.
FIG. 4 is a cross-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 Opposite substrate 18 Light-shielding part 20 Organic EL element substrate

Claims (4)

Display electrodes composed of a reflective material, a thin film transistor in which the display electrode for driving the liquid crystal are connected, has a first substrate provided with an electroluminescent element, and a second transparent substrate opposed to the first substrate, both A light guide hole in which the liquid crystal is filled between substrates, the electroluminescence element is laminated between the display electrode and the first substrate, and light emitted from the electroluminescence element is provided in the display electrode. A liquid crystal display device, wherein the liquid crystal is supplied to the liquid crystal via   A display electrode made of a reflective material; a first substrate having a thin film transistor connected to the display electrode to drive a liquid crystal; and a second transparent substrate facing the first substrate, and the substrate between the two substrates A liquid crystal display device comprising: a liquid crystal filling, wherein the second transparent substrate includes an electroluminescence element in a region other than the display electrode.   A display electrode made of a reflective material; a first substrate having a thin film transistor connected to the display electrode to drive a liquid crystal; and a second transparent substrate facing the first substrate, and the substrate between the two substrates A liquid crystal display device filled with liquid crystal, wherein a light shielding portion is disposed on a surface of the second substrate facing the first substrate, and an electroluminescence element is provided at the light shielding portion arrangement portion. A liquid crystal display device.   A display electrode made of a reflective material and having a light guide hole which is a light guide hole, a first transparent substrate provided with a thin film transistor to which the display electrode is connected and which drives a liquid crystal, and opposed to the first transparent substrate A liquid crystal display device comprising: a second transparent substrate; and the liquid crystal filled between both substrates, wherein a third substrate having an electroluminescence element at a position corresponding to the light guide hole is provided in the first substrate. A liquid crystal display device, wherein the liquid crystal display device is provided so as to face a transparent substrate, and the light emitted from the electroluminescence element is supplied to the liquid crystal through the light guide hole.

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