JP2003255377A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve quality of a reflection type and a semi-transmission type LCD (liquid crystal display). <P>SOLUTION: In a display device, TFTs (thin film transistors) 110 which are the switching elements provided for every pixel are formed on a first substrate 100 and a base material film 50 whose work function is similar to that of the transparent electrode 250 of a second substrate 200 and which consists of IZO (Indium Zinc Oxide), ITO (Indium Tin Oxide), Mo (Molybdenum) and the like is connected to each TFT 110 and a reflecting electrode 44 which reflects rays of light entering from the side of the second substrate 200 is formed on the material film 50. A liquid crystal layer 300 is AC driven with satisfactory symmetry by a transparent electrode 250 and the reflecting electrode 44 whose electric characteristic is adjusted while providing a plurality of minute opening parts 46 in the reflection electrode 44 and exerting the influence of the electric characteristic of the base material film 50 on the surface of the electrode 44 with these opening parts 46. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective or semi-transmissive display device having a reflective function.

[0002]

2. Description of the Related Art A liquid crystal display device (hereinafter referred to as LCD) has a feature that it is thin and has low power consumption, and is currently widely used as a monitor for computer monitors and portable information equipment. In such an LCD, liquid crystal is sealed between a pair of substrates, and the display is performed by controlling the orientation of the liquid crystal that is formed between the substrates and is positioned between the electrodes by a CRT (cathode ray tube) display or ,
In principle, unlike an electroluminescence (EL) display and the like, it does not emit light by itself, and thus requires a light source to display an image to an observer.

Therefore, in a transmissive LCD, a transparent electrode is used as an electrode formed on each substrate, a light source is arranged at the back or side of the liquid crystal display panel, and the amount of light transmitted from this light source is controlled by the liquid crystal panel. Even if the surroundings are dark, bright display is possible. However, since the light source is always turned on for display, power consumption by the light source is unavoidable, and sufficient contrast cannot be ensured in an environment where outside light is extremely strong such as outdoors during the day. .

On the other hand, in the reflection type LCD, external light such as the sun or room light is used as a light source, and ambient light incident on the liquid crystal panel is reflected by a reflective electrode formed on the substrate on the non-observation surface side. Then, display is performed by controlling, for each pixel, the amount of light emitted from the liquid crystal panel that is incident on the liquid crystal layer and reflected by the reflective electrode. In this way, the reflective LCD is
Since external light is used as the light source, the display cannot be seen without external light, but unlike a transmissive LCD, it does not consume power from the light source and has very low power consumption. can get. However, this reflective LCD has a problem that it is insufficient in comparison with a transmissive LCD in terms of general display quality such as color reproducibility and display brightness.

On the other hand, in a situation where the demand for lower power consumption of devices is further increased, the reflective LCD, which consumes less power than the transmissive LCD, is advantageous. Therefore, the reflective LCD is suitable for use in high-definition monitors of portable devices. This is being attempted, and research and development for improving display quality are being conducted.

FIG. 5 shows a plane structure (first substrate side) per pixel of a conventional active matrix type reflective LCD having a thin film transistor (TFT) for each pixel, and FIG. , C- of this FIG.
The schematic cross-sectional structure of the reflective LCD at a position along the line C is shown.

The reflective LCD is constructed by enclosing a liquid crystal layer 300 between a first substrate 100 and a second substrate 200 which are attached to each other with a predetermined gap. A glass substrate, a plastic substrate, or the like is used as the first and second substrates 100 and 200. In at least this example, a transparent substrate is used as the second substrate 200 arranged on the observation surface side.

A TFT 110 is formed for each pixel on the liquid crystal side surface of the first electrode 100. This TFT11
A data line 136 for supplying a data signal to each pixel is connected to, for example, the drain region of the active layer 120 of 0 through a contact hole formed in the interlayer insulating film 134, and the source region is connected to the interlayer insulating film 134 in the source region. And a first pattern formed in an individual pattern for each pixel through a contact hole formed so as to penetrate the planarization insulating film 138.
It is connected to the electrode (pixel electrode) 150.

As the first electrode 150, Al, Ag or the like having a reflection function is used, and an alignment film 160 for controlling the initial alignment of the liquid crystal layer 300 is formed on the reflection electrode 150. There is.

In the case of a color display device, a color filter (R, G, B) 210 is formed on the liquid crystal side of the second substrate 200 which faces the first substrate 100, and the second electrode is formed on the color filter 210. As an ITO (Indium Tin Oxi
A transparent electrode 250 using a transparent conductive material such as de) is formed. Further, on the transparent electrode 250, the first
An alignment film 260 similar to that on the substrate side is formed.

The reflection type LCD has the above-mentioned structure, and controls the amount of light which is incident on the liquid crystal panel, reflected by the reflection electrode 150, and emitted again from the liquid crystal panel for each pixel to obtain a desired amount. Display.

[0012]

The present invention is not limited to the reflection type, but is not limited to the LC type.
In D, the liquid crystal is driven with an alternating voltage to prevent image sticking. In the transmissive LCD, both the first electrode on the first substrate and the second electrode on the second substrate are required to be transparent, and both employ ITO as an electrode material. Therefore, when alternating-current driving the liquid crystal, the first and second electrodes can apply positive and negative voltages to the liquid crystal under substantially the same conditions.

However, as shown in FIG. 6, the first electrode 15
In a reflective LCD using a reflective electrode made of a metal material as 0 and a transparent electrode made of a transparent metal oxide material such as ITO as the second electrode 250, display flicker or liquid crystal may occur depending on driving conditions. The problem of image sticking sometimes occurred. This is remarkable when the liquid crystal is driven at, for example, the recently reported limit flicker frequency (CFF) or less. Driving below CFF means L
For the purpose of further lowering the power consumption of the CD, the drive frequency of the liquid crystal (≈data writing frequency to the liquid crystal (liquid crystal capacitance) in each pixel formed in the region facing the first and second electrodes) is set to, for example, Lower than 60 Hz, which is the standard of the NTSC standard, etc., can be perceived as flicker by human eyes.
This is an attempt to set 0 Hz to 30 Hz. However, it has been found that when each pixel of the conventional reflective liquid crystal panel is driven at such a frequency of CFF or less, the above-mentioned problems of flicker and image sticking of liquid crystal become remarkable, and display quality is significantly deteriorated. .

As a result of the applicant's research on the cause of flicker and liquid crystal burn-in of the reflection type LCD as shown in FIGS. It was found that one of the causes was the asymmetry of the physical properties. This asymmetry is the second
The work function of a transparent metal oxide such as ITO used for the electrode 250 is about 4.7 eV to 5.2 eV, whereas the work function of a metal such as Al used for the first electrode 150 is 4.2 eV to 4 eV. It is considered that this is due to the large difference of about 0.3 eV. The difference in work function causes a difference in the charges actually induced at the liquid crystal interface via the alignment films 160 and 260 when the same voltage is applied to each electrode. Then, due to the difference in charges induced at the interface of the alignment film of the liquid crystal, impurity ions in the liquid crystal layer are biased to one electrode side, and as a result, the residual DC voltage is accumulated in the liquid crystal layer 300. The lower the driving frequency of the liquid crystal, the greater the influence of the residual DC on the liquid crystal, and the more noticeable the occurrence of flicker and the image sticking of the liquid crystal. Therefore, driving at CFF or less is practically difficult. .

It should be noted that the reflective LCD is the first conventional type.
Also, a structure is known in which ITO is used for the second electrode as in a transmissive LCD, and a separate reflection plate is provided outside the first substrate (on the side not facing the liquid crystal). However, when the reflection plate is provided outside the first substrate, the transparent first electrode 150 and the transparent first electrode 150 are provided.
The optical path length is extended by the thickness of the substrate, and display quality is likely to deteriorate due to parallax. Therefore, in a reflective LCD for display applications that require high display quality, a reflective electrode is used as a pixel electrode. As described above, when the driving frequency is lowered, flicker occurs, and thus driving is performed to reduce power consumption. The frequency could not be lowered.

In order to solve the above-mentioned problems, the present invention has a reflective function that has the same electrical characteristics of the first and second electrodes with respect to the liquid crystal layer, is free from the influence of flicker and parallax, and has high display quality and low power consumption. An object of the present invention is to realize a display device provided with the display device.

[0017]

In order to achieve the above object, the present invention provides a display for each pixel, in which a liquid crystal layer is enclosed between a first substrate and a second substrate on which electrodes are formed. In the display device, the first substrate is formed by covering a base material film having a work function similar to that of the transparent electrode on the second substrate side and the base material film, and forming a second substrate on the liquid crystal layer. And a plurality of fine openings are formed in the reflecting electrode.

According to another aspect of the present invention, there is provided a display device configured to enclose a liquid crystal layer between a first substrate and a second substrate on which electrodes are respectively formed to perform display for each pixel. 1 substrate is a switch element provided for each pixel,
A base material film formed on an insulating film covering the switch element and made of a material having a work function similar to that of the transparent electrode on the second substrate side, and covering the base material film connected to the switch element and the base material film. Formed on the liquid crystal layer and electrically connected to the switch element through the base material film.
A reflecting electrode for reflecting light incident from the substrate side, and the reflecting electrode is formed with a plurality of fine openings.

As described above, on the base material film having a work function similar to that of the transparent electrode on the second substrate side on the first substrate side,
By forming a reflective electrode having a plurality of fine openings, the influence of the underlying material layer on the reflective electrode surface is exerted even if the transparent electrode and the reflective electrode having different electrical characteristics are arranged on the liquid crystal layer side. It becomes possible. Therefore, the liquid crystal layer can be driven with good symmetry by the transparent electrode and the reflective electrode. In particular, even when the driving frequency of the liquid crystal layer in each pixel is set lower than 60 Hz, for example, it is possible to display with high quality without causing flicker.

In another aspect of the present invention, in the display device, each of the openings has a diameter of 10 μm or less,
The ratio of the plurality of openings to the reflective electrode region is 20% or less.

If the diameter of the opening is 10 μm or less, it is possible to prevent the characteristic difference between the opening region and the non-opening region on the surface of the reflective electrode from becoming too large and the display quality from being deteriorated due to the characteristic difference. . The characteristics include, for example, the degree of flicker and image sticking, and optical conditions. In addition, the reflection function of the reflection electrode can be maintained by suppressing the ratio of the openings to about 20%.

In another aspect of the present invention, in the above display device, the difference between the work function of the underlying material film and the work function of the transparent conductive material of the transparent electrode on the second substrate side is 0.5e.
It is V or less.

In another aspect of the present invention, in the display device, the base material film is formed using a conductive material.

According to another aspect of the present invention, in the display device, the driving frequency of the liquid crystal layer in each pixel is 60 Hz.
Lower.

By using the above-mentioned base material film, the characteristics on the surface of the reflective electrode (the surface facing the liquid crystal layer) can be surely brought close to the transparent electrode on the second substrate side.
If a conductive material is used for the underlying material film, for example, when a switch element is provided, the underlying material film below the reflective electrode is connected to this switch element, and the reflective electrode is formed on the underlying material film. By doing so, it is possible to electrically connect the reflective electrode and the switch element without providing a special configuration, and minimize the addition of steps by adopting the laminated structure of the base material film and the reflective electrode. be able to.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

FIG. 1 is a partial plan view of a reflective active matrix LCD as a reflective LCD according to this embodiment on the first substrate side, and FIG. 2 is an LCD at a position along line AA in FIG. 2 shows a schematic sectional configuration of In an active matrix type LCD, a plurality of pixels are provided in a matrix in a display area, and a switching element such as a TFT is provided for each pixel. The switch element is formed for each pixel on one of the first and second substrates, for example, the first substrate 100 side, and the interlayer insulating film 34 and the flattening insulating film 38 are formed on each switch element. In an embodiment,
A base material film 50 having a work function similar to that of the transparent electrode (common electrode) 250 of the second substrate 200 and having an individual pattern for each pixel is formed on the flattening insulating film 38.

The reflective electrode 44 is made of a metal material having a good reflective property, and is formed in an individual pattern for each pixel, covering the base material film 50. A plurality of minute openings 46 are formed in the reflective electrode 44.

Here, in the present embodiment, as the switching element of each pixel, the channel 20c and the drain / source region 2 are used.
A polycrystalline silicon TFT 110 using polycrystalline silicon for the active layer 20 including 0d · 20s is adopted. Of course, not only polycrystalline silicon but also amorphous silicon TFT may be used.

As the base material film 50, specifically, it is preferable to use a material having a work function difference of, for example, about 0.5 eV or less. Examples of such a material include IZO (Indium Zinc Oxide) and I, which are the same as those of the transparent electrode 250.
A transparent conductive material such as TO, a conductive material such as molybdenum, or another non-conductive material can be used. In the example of FIGS. 1 and 2, the base material film 50 is I
A conductive material such as ZO is used, and the base material film 50 is also formed in the contact hole formed in the interlayer insulating film 34.
Is formed, it is electrically connected to the source electrode 40 of the TFT 110.

The reflective electrode 44 is directly formed on the base material film 50. Therefore, in the present embodiment, the reflective electrode 44 is electrically connected to the source electrode 40 of the TFT 110 via the base material film 50. Therefore, when a gate signal (scanning signal) is applied to the gate electrode 32 of the TFT 110 and the TFT 110 is turned on, for example, the voltage on the source electrode 40 side becomes the data signal voltage applied to the drain electrode (data line) 36. Therefore, the data signal voltage becomes equal, and the data signal voltage is applied to the reflective electrode 44 through the source electrode 40 and the base material film 50.

As the first and second substrates 100 and 200, transparent substrates such as glass are used. On the side of the second substrate 200 facing the first substrate 100, in the case of a color type, as in the conventional case. The color filter 210 is formed, and the transparent electrode 25 made of a transparent conductive material is formed on the color filter 210.
0 is formed. As the transparent conductive material, IZO, ITO or the like is adopted as described above. In the active matrix type, the transparent electrode 250 is formed as a common electrode for each pixel. An alignment film 260 made of polyimide or the like is formed on the transparent electrode 250.

On the side of the first substrate 100, which is arranged opposite to the side of the second substrate having the above-mentioned structure, an alignment film 60 made of polyimide or the like is formed on the contact surface with the liquid crystal, like the second substrate. The reflective electrode 44 is formed on the lower layer of the alignment film 60 as described above. As described above, the plurality of minute openings 46 are formed in the reflective electrode 44. Due to the presence of the openings 46, the transparent electrode 250 of the second substrate and the transparent electrode 250 of the second substrate are formed on the surface (the liquid crystal facing surface) of the reflective electrode 44. The underlying material film 50 having similar electrical characteristics is affected. Therefore, the characteristic of the surface of the reflective electrode 44, which is originally different in electrical characteristic from the transparent electrode 250, can be brought close to the characteristic of the transparent electrode 250, and the liquid crystal layer 300 is symmetrical by the transparent electrode 250 and the reflective electrode 44. AC drive with good performance. Therefore, even if the drive frequency of the liquid crystal is set to the CFF or less as described above, flicker and image sticking of the liquid crystal do not occur.
High quality display is possible.

As the reflective electrode 44, a material having excellent reflective characteristics such as Al, Ag, or an alloy of these (Al-Nd alloy in this embodiment) is used at least on the liquid crystal layer side. The thickness of the electrode 44 is, for example, about 1000Å. The plurality of openings 46 of the reflective electrode 44 are formed in the base material film 5
When a reflective electrode material is laminated on 0 and formed into an individual pattern for each pixel by photolithography, it can be formed simultaneously. That is, if a pattern for the opening is also formed in the pattern mask for forming the reflective electrode, the opening 46 is formed in the reflective electrode formation region at the same time as the patterning of the reflective electrode 44 without adding a special process. be able to.

If each opening 46 is too large, the difference in characteristics between the opening region and the non-opening region becomes large. Therefore, the size of the opening 46 has a diameter of, for example, 10 μm or less,
More preferably, the thickness is 5 μm or less. The shape of the opening 46 is not particularly limited, but a shape that allows easy opening (easy etching), for example, a circular shape as shown in the drawing can be adopted.

Further, if the proportion of the opening 46 in the reflective electrode 44 is too large, the reflective area of the reflective electrode 44 is reduced, so that the reflectance is lowered and the reflective function is impaired. Therefore, the ratio of the opening 46 to the area where the reflective electrode 44 is formed (the area of the reflective electrode when the opening is not formed) is preferably 20% or less, more preferably 10% or less. Here, as the base material film 50, it is also possible to employ an opaque refractory metal layer such as Mo having a work function similar to that of the transparent electrode 250 as described above. M
If it is o or the like, since it has a light reflecting function unlike IZO or the like, light can be reflected by the base material film 50 even in the opening region. However, the reflectance of Mo or the like is lower than that of Al or the like used for the reflective electrode material, and it is preferable to keep the ratio of the opening 46 to about 20%.

The opening 46 in the reflection electrode 44 is provided.
The arrangement may be regular or random, but it is preferable that the arrangement is such that interference such as moire fringes does not easily occur. Therefore, a somewhat random arrangement is preferable.

When a transparent conductive material such as IZO or ITO is used as the base material film 50, the base material film 5
0 can be formed by using the process of forming the transparent pixel electrode of the transmissive LCD. Also, as will be described later, a transflective LC
In order to realize D, it is possible to form the transparent underlayer material film 50 over the entire area of one pixel and change the area of the reflective electrode 44 into a pattern smaller than that of the reflective type. When the reflective electrode 44 made of Al or the like is formed on the upper layer of the underlying material film 50 such as IZO, the underlying material film 50 and the reflective electrode 44 can be brought into ohmic contact with each other without any special treatment.

On the other hand, when a refractory metal material such as Mo is used for the base material film 50, for example, Mo has a high affinity with the flattening insulating film 38 below it, and also with the source electrode 40 and the reflective electrode 44. Since the contact property is excellent, the reliability as a display device can be improved. When Mo or the like is adopted as the base material film 50, this material film 5
Since 0 has a higher conductivity than a transparent conductive material or the like, even if the reflective electrode 44 is thin, the TFT 11
The electrical resistance between 0 and the reflective electrode 44 can be suppressed sufficiently low. Therefore, for example, instead of providing the opening 46, or forming the opening 46, the reflective electrode 4 is formed.
It is possible to adopt a configuration in which the influence of the characteristics of the base material film 50 is exerted on the surface of the reflective electrode 44 by reducing the thickness of 4. In such a configuration, for example, the thickness of the reflective electrode 44 is 100Å
This can be dealt with by setting the thickness to about 200 Å and setting the thickness of the Mo film as the base material film 50 to about 500 Å.

In the structure of FIG. 2, the flattening insulating film 38
An inclined surface having a desired angle is formed in each of the pixel regions, a base material film 50 is formed so as to cover the flattening insulating film 38, and the reflective electrode 44 is laminated thereon. Then, the same inclination as that of the planarization insulating film 38 is formed on the surface of the reflective electrode 44. If such an inclined surface is formed at an optimum angle and position, external light can be condensed and emitted for each pixel, and it is possible to improve the display brightness at the front position of the display, for example. is there. Of course, such an inclined surface does not necessarily have to exist.

Next, an example of application to the transflective LCD having the above structure will be described. FIG. 3 shows a schematic plan configuration of an active matrix type transflective LCD. The difference from the configuration of FIG. 1 is that the area where the reflective electrode 44 is formed on the underlying material film 50 made of a transparent conductive material is smaller than one pixel area and the area where the reflective electrode 44 is not formed is the underlying material. The film 50 spreads and functions as a display electrode, and is otherwise common. Such a transflective LCD
Also, in the reflective electrode 44 formed on the base material film 50, a plurality of fine openings 46 are formed,
The electrical characteristics of the surface of No. 4 can be made close to the characteristics of the common electrode 250. Also, the characteristics of the reflective area can be made close to the characteristics of the transmissive area. Therefore, the liquid crystal layer 300 can be driven with good symmetry, the difference in characteristics between the transmissive region and the reflective region can be reduced, and the light source can be switched according to the intensity of ambient light or the like to perform reflective display or transmissive display. Both can achieve high display quality.

Although the reflective or semi-transmissive LCD having the reflective layer 44 has been described above, the structure of the switch element (TFT) according to the present invention, the base material film 50, and the reflective electrode 44 having the opening 46 is as follows. It can also be applied to an EL display, which allows the electrodes on the substrate side to have a reflection function. FIG. 4 shows a partial sectional structure of each pixel of the active matrix type EL display according to this embodiment.

The element adopted in the EL display of FIG. 4 is an organic EL using an organic compound as a light emitting material.
The element 90 is an organic element layer 88 formed between an anode 80 and a cathode 86. The organic element layer 88 includes at least a light emitting layer 83 containing an organic light emitting functional molecule, and can be formed of a single layer structure, two layers, three layers or more multilayer structures depending on the characteristics of the organic compound, the emission color and the like. Figure 4
In the example, the organic element layer 88 has a hole transport layer 82 / light emitting layer 83 / electron transport layer 84 formed in this order from the anode 80 side arranged on the substrate side 100, and the light emitting layer 83 is the same as the anode 80. An individual pattern is formed for each pixel, and the hole transport layer 82
Also, the electron transport layer 84 is formed commonly to all the pixels, similarly to the cathode 86. In addition, each anode 80 is insulated between adjacent pixels, and the cathode 8 of the upper layer is provided in the edge region of the anode 80.
A flattening insulating film 39 is formed in a region between the anodes of adjacent pixels for the purpose of preventing a short circuit with the pixel 6.

In this organic EL element 90, holes injected from the anode 80 and electrons injected from the cathode 86 are recombined in the light emitting layer 83 to excite the organic light emitting molecules, and when the organic light emitting molecules return to the ground state. Light is emitted. The organic EL element 90 is a current-driven light emitting element, and the anode 80 is the organic element layer 8
It is necessary to have a sufficient hole injection ability with respect to No. 8, and a transparent conductive material such as ITO or IZO having a high work function is usually used. Therefore, the light from the light emitting layer 83 passes through the transparent substrate 100 from the transparent anode 80 side and is emitted to the outside. On the other hand, in the active matrix type organic EL display shown in FIG. 4, IT having a high work function is used.
Base material film 50 made of O, IZO, or Mo
And a reflective electrode 44 having an opening 46 formed thereon.
The light-reflecting anode 80 is realized by stacking the above. That is, the interface of the reflective electrode 44 with the organic element layer 88 is affected by the high work function of the underlying material film 50 through the opening 46, and thus the reflective electrode 44 having a low hole injection capability alone.
Therefore, holes can be injected into the organic element layer 88.
Further, the light obtained from the light emitting layer 83 can be reflected upward on the surface of the reflective electrode 44 having a high reflectance.

[0045]

As described above, according to the present invention, when a reflective electrode is required on one substrate side as in a reflective or transflective LCD, a plurality of openings are provided in the reflective electrode. The surface characteristics can be made close to the characteristics of the base material film, that is, the characteristics of the other transparent electrode. Therefore, the liquid crystal can be AC-driven with good symmetry with a simple configuration, and even if the drive frequency of the liquid crystal is set to, for example, CFF or less, flicker does not occur and burn-in does not occur. High-quality display can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic plan configuration on a first substrate side of an active matrix reflective LCD according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic sectional configuration of a reflective LCD at a position along line AA in FIG.

FIG. 3 is a diagram showing a schematic plan configuration of a first substrate side of an active matrix type transflective LCD according to an embodiment of the present invention.

FIG. 4 is an active matrix type organic EL device of the present invention.
It is a figure which shows the schematic cross-section of a display.

FIG. 5: Conventional active matrix reflective LC
It is a figure which shows the 1st board | substrate side partial planar structure in D.

6 is a diagram showing a schematic cross-sectional structure of a conventional reflective LCD at a position along line CC of FIG.

[Explanation of symbols]

20 active layer (p-Si layer), 30 gate insulating film, 3
2 gate electrode (gate line), 34 interlayer insulating film,
36, 37 drain electrode (data line), 38, 3
9 flattening insulating film, 40 source electrode, 44 reflective electrode, 46 opening, 50 base material film, 60, 260
Alignment film, 80 Anode, 82 Hole transport layer, 83 Light emitting layer, 84 Electron transport layer, 86 Cathode, 88 Organic device layer, 90 Organic EL device, 100 First substrate, 110
TFT, 200 second substrate, 210 color filter,
250 second electrode, 300 liquid crystal layer.

Continued front page    F-term (reference) 2H091 FA14Y FD04 GA02 GA03                       GA07 GA11 LA12 LA16                 2H092 HA05 JA45 JA46 JB07 JB16                       NA01 PA06 PA12                 5F110 AA09 BB01 CC02 GG02 GG13                       GG15 HM18 NN02 NN72

Claims (6)

[Claims] 1. A display device configured to enclose a liquid crystal layer between a first substrate and a second substrate on which electrodes are formed to perform display for each pixel, wherein the first substrate is the first substrate. 2 a transparent electrode on the side of the substrate, a base material film having a work function similar to that of the transparent electrode, and a reflective electrode formed to cover the base material film and reflect light incident on the liquid crystal layer from the side of the second substrate. A display device characterized in that a plurality of fine openings are formed in the reflective electrode. 2. A display device configured to enclose a liquid crystal layer between a first substrate and a second substrate on which electrodes are formed to perform display for each pixel, wherein the first substrate is for each pixel. And a base material film formed on the insulating film covering the switch element and made of a material having a work function similar to that of the transparent electrode on the second substrate side and connected to the switch element. And a reflective electrode formed to cover the base material film, electrically connected to the switch element via the base material film, and reflecting light incident on the liquid crystal layer from the second substrate side. The display device is characterized in that the reflective electrode is formed with a plurality of fine openings. 3. The display device according to claim 1, wherein each of the openings has a diameter of 10 μm or less, and a ratio of the plurality of openings to the reflective electrode region is 20%.
A display device characterized by the following. 4. The display device according to claim 1, wherein a work function of the underlying material film and a work function of a transparent conductive material of the transparent electrode on the second substrate side are provided. A display device characterized in that the difference is 0.5 eV or less. 5. The display device according to claim 4, wherein the base material film is formed using a conductive material. 6. The liquid crystal display device according to claim 4, wherein the driving frequency of the liquid crystal layer in each pixel is lower than 60 Hz.