JP2000019563A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device which is good in utilization efficiency of circumferential light and backlight light and is capable of making excellent display under any light environment. SOLUTION: A plurality of gate wiring 2 and a plurality of source wiring 3 are disposed in a transparent insulative substrate so as to intersect orthogonally with each other. TFT 4 is installed near the intersect part of the wiring. A pixel electrode 6 connected to each TFT 4 consists of two regions; a region A where transmission efficiency is high and a region B where reflection efficiency is high. For example, the front surface of the former is provided with ITO 7 which is a transparent electrode and the latter with Al or Al alloy 8, respectively. Since the pixel electrodes 6 are superposed on the gate wiring 2a of the ensuring stage via a gate insulating film and, therefore, the auxiliary capacitors for use at the time of liquid crystal driving are formed in these parts at the time of driving.

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 having a transmissive display area and a reflective display area.

[0002]

2. Description of the Related Art A liquid crystal display device has the advantages of being thin and of low power consumption, and is intended for office automation equipment such as a word processor and a personal computer, portable information equipment such as an electronic organizer, or a camera having a liquid crystal monitor. Widely used for body VTRs and the like.

Further, unlike a CRT (CRT) or an EL (electroluminescence) display, the liquid crystal display panel mounted on the liquid crystal display device does not emit light by itself.
A so-called transmissive liquid crystal display device in which an illuminating device formed of a fluorescent tube called a backlight is installed on the back or side of the device and an image is displayed by controlling the amount of backlight light transmitted by a liquid crystal display panel is often used. I have.

However, in a transmission type liquid crystal display device,
Normally, the backlight is 5% of the total power consumption of the liquid crystal display.
Since it occupies 0% or more, providing a backlight increases power consumption.

Therefore, in addition to the above-mentioned transmissive liquid crystal display device, in a portable information device having many machines that are used outdoors or at all times, a reflector is provided on one substrate instead of a backlight, and ambient light is reflected on the surface of the reflector. 2. Related Art A reflection type liquid crystal display device which performs display by reflecting light from the LCD has been used.

A display mode used in a reflection type liquid crystal display device uses a polarizing plate such as a TN (twisted nematic) mode and an STN (super twisted nematic) mode which are widely used in a transmission type liquid crystal display device at present. In recent years, a phase change type guest-host mode that can realize a bright display because a polarizing plate is not used has been actively developed.

However, the reflection type liquid crystal display device utilizing the reflected light of the ambient light has a drawback that the visibility is extremely reduced when the ambient light is dark. On the other hand, in the case of a transmissive liquid crystal display device, when the ambient light is very bright, contrary to the reflective liquid crystal display device, there is a problem that the display light cannot be observed because the display light is darker than the ambient light. In order to be able to observe, it is necessary to increase the intensity of the backlight light, so that there is a problem such as an increase in power consumption of the liquid crystal display device due to the backlight.

Therefore, in order to solve the above-mentioned problem, a semi-transmissive reflection film which transmits a part of light and reflects a part of light is conventionally used as disclosed in JP-A-7-333598. Accordingly, a configuration is disclosed in which both a transmissive display and a reflective display are realized by one liquid crystal liquid crystal display device.

FIG. 28 shows a liquid crystal display device using the transflective film. The liquid crystal display device includes a polarizing plate 30, a retardation plate 31, a transparent substrate 32, a black mask 33, a counter electrode 3
4, alignment film 35, liquid crystal layer 36, MIM 37, pixel electrode 3
8, a light source 39, and a reflection film 40.

The pixel electrode 38, which is a semi-transmissive reflective film, is formed by depositing metal particles very thinly over the entire surface of a pixel, or by forming minute hole defects, dent defects, and the like on the surface. The light from the light source 39 is transmitted through the pixel electrode 38 and the external light such as natural light or indoor illumination light is reflected by the pixel electrode 38, thereby realizing the transmissive display function and the reflective display function at the same time. Can be.

[0011]

However, FIG.
The following problems occur in the display device shown in FIG.
First, when the above-mentioned semi-transmissive reflective film is formed by depositing metal particles in a very small thickness, the metal particles are materials having a large absorption coefficient, so that the internal absorption of incident light is large and absorption light not used for display is also generated. This causes a problem that light utilization efficiency is poor. For example, even if 100% of light is incident, only 30% of light can be used for transmission and 15% of light can be used for reflection.

On the other hand, when a film in which minute hole defects, dent defects, and the like are scattered in the plane is used as the pixel electrode 38, the structure of the film is too complicated, and precise design conditions are involved in manufacturing, so that control is required. And it is difficult to produce a film having uniform characteristics. In other words, the reproducibility of the electrical characteristics and optical characteristics is poor, and it has been extremely difficult to control the display quality as a liquid crystal display device.

For example, if a thin film transistor (TFT) generally used as a switching element of a liquid crystal display device in recent years is to be employed in the above-mentioned conventional technology, an electrode for forming an auxiliary capacitance in a pixel is replaced with another electrode.
In some cases, it is formed by a wiring material. However, when a transflective film is used as a pixel electrode as in the above-described related art, there is a problem that it is not suitable for forming an auxiliary capacitance. Furthermore, even when a pixel electrode is formed so as to cover a part of these wirings or elements via an insulating layer, there is a problem that it is difficult to contribute to an improvement in aperture ratio because a transmission component coexists. Further, if light enters a semiconductor layer of a switching element such as an MIM or a TFT, a photoexcitation current is generated. Therefore, even if a semi-transmissive reflective film is used as a light-shielding layer, it is necessary to further provide a light-shielding film on the counter substrate side. Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a liquid crystal display device which simultaneously realizes a transmission type display and a reflection type display on a single substrate has a greater peripheral area than a conventional liquid crystal display device. An object of the present invention is to provide a liquid crystal display device in which the utilization efficiency of light and backlight light is improved, the quality is stabilized, and the production is simplified.

[0015]

A liquid crystal display device according to the present invention has a liquid crystal layer sandwiched between at least two substrates, and includes a plurality of pixels defined by a pair of electrodes for applying a voltage to the liquid crystal layer. In the liquid crystal display device, a region having a high transmission efficiency and a region having a high reflection efficiency are provided in the plurality of pixels, and a layer having a high transmission efficiency or a layer having a high reflection efficiency functions as a pixel electrode in each of the plurality of pixels. This improves light use efficiency, thereby solving the above-mentioned problem.

It is preferable that the plurality of pixels are surrounded by a plurality of gate wirings formed on a substrate and a plurality of source wirings arranged orthogonal to the gate wirings.

It is preferable that the region having a high reflection efficiency covers a part of the gate wiring or the source wiring or any one of the switching elements.

The layer having high transmission efficiency or high reflection efficiency is
It is desirable that the gate wiring or the source wiring be formed of a material constituting either of the gate wiring and the source wiring.

Only the layer having a high transmission efficiency may function as a pixel electrode, and the layer having a high reflection efficiency may be electrically insulated from the layer having a high transmission efficiency.

More preferably, the area ratio of the high reflection efficiency area to the pixel area (pixel area for applying a voltage to the liquid crystal) is 10 to 90%.

The operation of the above configuration will be described below.

According to the first aspect of the present invention, a region having a higher transmission efficiency and a region having a higher reflection efficiency than the transflective film are provided in each pixel, and a layer having a higher transmission efficiency or a higher reflection efficiency is provided in each region. Since the layer functions as a pixel,
Unlike a liquid crystal display device using a conventional transflective film, for example, the use efficiency of ambient light and illumination light does not decrease due to the stray light phenomenon. Further, the electro-optical characteristics are different between the transmission mode that passes through the liquid crystal layer once and the reflection mode that passes through the liquid crystal layer twice. Therefore, in the present invention, a region having high transmission efficiency and a region having high reflection efficiency are clearly separated. For example, by changing the cell thickness of the liquid crystal layer between the region having high transmission efficiency and the region having high reflection efficiency, changing the applied voltage, or changing the type of the phase difference plate, etc. , Both modes can be adjusted for consistency. Therefore, no matter how much the brightness of the ambient light, as a reflective display, as a transmissive display, or as a dual-purpose display,
A good image can always be displayed. Also, since both the backlight light and the ambient light can be simultaneously and efficiently contributed to the display, the power consumption is remarkably reduced as compared with a so-called transmissive liquid crystal display device that always uses only strong backlight light. It is possible to reduce it.

That is, there is a disadvantage that the visibility is extremely reduced when the ambient light is dark, which is a problem in the conventional reflection type liquid crystal display device, and the ambient light is very bright, which is a conventional transmission type liquid crystal display device. The disadvantage that the display becomes difficult to see in such a case can be solved at the same time by improving the light use efficiency by the present invention.

According to the second aspect of the present invention, a region having a higher transmission efficiency and a region having a higher reflection efficiency than the transflective film are provided in each pixel, and a layer having a higher transmission efficiency or a higher reflection efficiency is provided in each region. Since the layer functions as a pixel electrode, it can be used as a reflective display, a transmissive display, or a dual-purpose display regardless of the brightness of ambient light.
A good image can always be displayed. Also, since both the backlight light and the ambient light can be simultaneously and efficiently contributed to the display, the power consumption is remarkably reduced as compared with a so-called transmissive liquid crystal display device that always uses only strong backlight light. It is possible to reduce it.

According to the third aspect of the present invention, the region having high reflection efficiency covers any part of the gate wiring or the source wiring or the switching element. It is possible to contribute to display, and as a result, the effective area of the pixel can be significantly improved. In addition to solving the above-mentioned problems of the related art using the transflective film, the pixel aperture ratio can be improved even in comparison with a general transmissive liquid crystal display device.

According to the fourth aspect of the present invention, since the material forming the region having high transmission efficiency or the region having high reflection efficiency is the same as the material forming the source wiring or the gate wiring, the manufacturing process of the liquid crystal display device is performed. Becomes easier.

According to the fifth aspect of the present invention, since the pixel electrode is composed of only the layer having high transmission efficiency, for example, the layer having high transmission efficiency and the layer having high reflection efficiency are electrically connected to each other. When a pixel electrode for one pixel is used,
Compared to a case where one layer of a layer having high transmission efficiency and a layer having high reflection efficiency overlap each other to form one pixel electrode, the occurrence of defects due to the pixel electrode can be reduced, and the yield rate can be improved.

According to the invention of claim 6, by setting the area ratio of the region having high reflection efficiency to 10 to 90%, the ambient light is too bright and the display is obscured to make it difficult to see. And the problem that occurred with the conventional reflective LCD device that no observation could be made when the ambient light intensity was extremely weak. Even in this case, an optimal display can be performed as a reflective display, a transmissive display, or a dual use display.

[0029]

(Embodiment 1) Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a partial plan view of an active matrix substrate in the liquid crystal display device of the present embodiment, and FIG. 2 is a cross-sectional view taken along line AA of FIG.

In FIG. 1, a plurality of gate wirings 2 are provided on a transparent insulating substrate 1 made of glass or plastic.
And a plurality of source wirings 3 are arranged so as to be orthogonal to each other, a region surrounding these is a pixel, and a TFT 4 is provided near an intersection of the wirings. The pixel electrode 6 is connected to the drain electrode 5 of the TFT 4. This pixel electrode 6
Is formed from two regions, a region A having a high transmission efficiency and a region B having a high reflection efficiency when observed from above the substrate. In the present embodiment, a layer having a high transmission efficiency is formed on the upper surface of the former. ITO7 (Indium Tin Ox
Ide), and in the latter, Al or an Al-based alloy 8 is provided as a layer having a high reflection efficiency, and they constitute a pixel electrode 6 integrally. In addition, since the pixel electrode 6 is superimposed on the next-stage gate wiring 2a via the gate insulating film 9, an auxiliary capacitance for driving the liquid crystal is generated in this portion during driving.

The TFT 4 has a gate insulating film 9, a semiconductor layer 12 (shown in FIG. 2), a channel protective layer 13, and n ⁺ -Si serving as source / drain electrodes on a gate electrode 10 branched from the gate wiring 2. The layers 11 are sequentially laminated.

Although not shown, an orientation film is applied to the active matrix substrate as described above, and this is bonded to a counter substrate on which a transparent electrode and an orientation film are formed, a liquid crystal is sealed between the substrates, and a backlight is provided behind. The installation completes the liquid crystal display device of the present embodiment.

The liquid crystal used was a guest-host liquid crystal ZLI2327 (manufactured by Merck) mixed with a black dye and mixed with 0.5% of an optically active substance S-811 (manufactured by Merck). In addition, as a liquid crystal mode, an ECB mode in which a polarizing plate is arranged above and below a liquid crystal layer can be used. Further, when a color display is desired, this can be realized by disposing a color filter composed of a colored layer of red, green, blue or the like in front of the liquid crystal layer.

Hereinafter, a method for manufacturing the active matrix substrate of the present embodiment will be described. First, the gate wiring 2 and the gate electrode 10 are formed on the insulating substrate 1 with Ta.
Was formed, a gate insulating film 9 was formed on the entire surface of the substrate.
Subsequently, after a semiconductor layer 12 and a channel protection layer 13 are formed on the gate electrode 10, n is formed as a source / drain electrode.
^{A +} -Si layer 11 was formed.

Further, an ITO layer 3a is used as the source line 3.
The (lower layer) and the metal layer 3b (upper layer) are sequentially formed by sputtering, and then patterned. In the present embodiment, Ti is used as the metal layer 3b.

As described above, by forming the source wiring 3 in a two-layer structure, the metal layer 3b constituting the source wiring 3 is temporarily provided.
Are electrically connected by the ITO layer 3a even if there is a film defect in a part of the source wiring 3, there is an advantage that the disconnection failure of the source wiring 3 can be reduced.

Further, among the pixel electrodes 6 of the present embodiment,
The region A with high transmission efficiency formed of ITO 7 is formed by the same material and the same process as the ITO layer 3 a of the source wiring 3. The region B having a high reflection efficiency is Mo14
After Al and Al8 were formed by sputtering, patterning was performed. When the thickness of Al is 150 nm or more, a sufficiently stable reflection efficiency (about 90%) can be obtained. In the present embodiment, the thickness of Al is set to 150 nm.
The reflection efficiency becomes 90%, and ambient light can be effectively reflected. In addition, as a material having high reflection efficiency, Al
Alternatively, a metal such as Ag, Ta or W may be used in addition to the Al-based alloy.

In this embodiment, the pixel electrode 6 is formed of I
Although TO7 and Al8 were used, the present invention is not limited thereto.
By making the thickness of the l or Al-based alloy different, a region with high transmission efficiency and a region with high reflection efficiency are formed,
It may be used in the areas A and B. With such a configuration, the manufacturing process can be simplified as compared with the case where different materials are used. Alternatively, by using the same material as the metal layer 3b of the source wiring 3 and the material having high reflection efficiency (Al8 in this embodiment) constituting the region B, the same manufacturing as the conventional transmission type liquid crystal display device can be achieved. It can be formed by a process.

As described above, in the present embodiment, the region B having high reflection efficiency and the region A having high transmission efficiency are provided as the pixel electrodes 6, so that the pixel electrode 6 is compared with the liquid crystal display device using the conventional transflective film. As a result, a liquid crystal display device capable of performing transmissive display, reflective display, or both types of display while using ambient light or illumination light without loss is realized.

As the pixel electrode 6, ITO is formed over the entire area inside the pixel and over the next-stage gate wiring 2 a by a gate insulating film 9.
In the region B, Al8 is formed in an island shape at the pixel central portion on the ITO7 via Mo14 in the region B. Thus, ITO7 and A
18 are electrically connected to each other, so that two regions A,
B applies the same voltage to the liquid crystal by the same TFT 7. That is, when voltage is applied, a defect such as generation of a disclination line, which occurs because the alignment state of the liquid crystal partially differs in the same pixel, does not occur.

Further, Mo14 is present between ITO7 and Al8.
By intervening, it is possible to prevent the occurrence of electrolytic corrosion due to the contact between ITO 7 and Al 8 via the electrolytic solution in the manufacturing process.

In this embodiment, good display characteristics can be obtained by setting the area ratio between the area A and the area B to 60:40. Incidentally, the area ratio is not limited to this value, and the transmission efficiency or the reflection efficiency of the regions A and B,
And it may be changed appropriately according to the purpose of use.

In the present invention, the area ratio of the area B is preferably 10 to 90% with respect to the effective pixel area (the area obtained by adding the area A and the area B). When this ratio is less than 10%, that is, when the ratio of the area with high transmission efficiency to the pixels is too high, the external light is too bright and the display is fuzzy. The same problem occurs. Conversely, area B
When the area ratio exceeds 90%, the ratio of the area A is low even when the backlight is turned on and displayed when the ambient light becomes dark enough that the display cannot be observed only with the ambient light. The display is too hard to see.

In particular, when the battery is mounted in a product type in which the main use environment is outdoors, it is necessary to attach importance to the battery life, and the design is made such that the power consumption is prioritized and the external light can be used efficiently. There must be. Therefore,
It is desirable that the ratio of the region B having high reflection efficiency is 40 to 90%. Here, if the area ratio of the region B is 40%, the environment in which the display can be performed only by the reflection type is very limited, and the time when the backlight must be turned on becomes long, so that the battery life is shortened.

On the other hand, when mounted in a product form in which the main use environment is indoors, the design is such that the backlight light is used efficiently. Therefore, the ratio of the area B is 1
0 to 60% is desirable. If the area ratio of the area B exceeds 60%, the area of the area A through which the backlight transmits is small, and the brightness of the backlight needs to be significantly higher than that of, for example, a transmissive liquid crystal display device. The power is increased, and the efficiency of use of the backlight is reduced.

When the liquid crystal display device of the present invention is mounted on a battery-operated video camera, the brightness of the backlight can be adjusted to a brightness that is always easy to observe, regardless of the brightness of the ambient light. I was able to keep.
In particular, when used outdoors in fine weather, the backlight does not need to be turned on, so the power consumption is small, and the battery usage time is significantly extended compared to those equipped with a transmissive liquid crystal display device Was completed.

(Embodiment 2) Hereinafter, Embodiment 2 will be described with reference to the drawings. FIG. 3 is a partial plan view of an active matrix substrate in the liquid crystal display device of the present embodiment, and FIG. 4 is a cross-sectional view taken along line BB of FIG.

In this embodiment, when the portion where the pixel electrode is formed is observed from above, the region A having high transmission efficiency and the region B having high reflection efficiency are divided at the vicinity of the pixel center. It has become.

Note that the same reference numerals as those in the first embodiment are used for reference numerals in the drawing. The configuration and manufacturing process of the pixel and the TFT are the same as those in the first embodiment.

In FIGS. 3 and 4, ITO having high transmission efficiency is used.
7 is provided from the vicinity of the central stage in the pixel to the vicinity of the gate line of the own stage, and is partially connected to the drain electrode 5 of the TFT 4. In addition, Al8 having high reflection efficiency is superimposed on the ITO 7 at the pixel central portion via the Mo14, extends in the direction of the next-stage gate wiring 2 on the opposite side to the ITO 7, and a gate insulating film 9 is formed on the gate wiring 2. Overlaid.

Here, since ITO 7 and Al 8 are electrically connected via Mo 14, electrolytic corrosion due to ITO 7 and Al 8 is suppressed. Further, since the Al 8, that is, the region B is overlapped with the next-stage gate wiring 2 via the gate insulating film 9, an auxiliary capacitance is formed when driving the liquid crystal, and
Since the area B in this portion also contributes to display, the effective area of the pixel is significantly improved as compared with the conventional configuration.

In order to further improve the aperture ratio, TF
The above-mentioned Al8 is formed on T4 or source wiring 3 via an insulating film.
For example, a film having high reflection efficiency may be formed as the pixel electrode 6 (electrically connected to the drain electrode 5). In this case, however, it is necessary to appropriately consider the material of the insulating film, the material used for the insulating film, and the pattern design so that the image quality deterioration due to the parasitic capacitance between the TFT 4 and the source wiring 3 can be minimized.

Embodiment 3 Hereinafter, Embodiment 3 will be described with reference to the drawings. FIG. 5 is a partial plan view of the active matrix substrate in the liquid crystal display device of the present embodiment, and FIG. 6 is a cross-sectional view taken along line CC of FIG.

This embodiment is different from the second embodiment in that a common wiring 15 is provided below a region B having high reflection efficiency via a gate insulating film 9.

The reference numerals in the drawings are the same as those in the first and second embodiments. The configuration and manufacturing process of the pixel and the TFT are the same as those in the first and second embodiments unless otherwise specified.

In FIGS. 5 and 6, ITO having high transmission efficiency is used.
Reference numeral 7 is provided from the vicinity of the central part of the pixel to the vicinity of the gate line 2 of the own stage, and is connected to the drain electrode 5 of the TFT 4. In addition, Al8 having high reflection efficiency has M
It overlaps with the ITO 7 via o14, extends to the vicinity of the next-stage gate wiring 2a on the opposite side to ITO7, and overlaps with the lower common wiring 15 via the gate insulating film 9.

Here, since ITO7 and Al8 are electrically connected via Mo14, electrolytic corrosion due to ITO7 and Al8 is suppressed. Further, since Al 8, that is, the region B is superimposed on the common wiring 15 via the gate insulating film 9, an auxiliary capacitance is formed at the time of driving the liquid crystal, so that good display can be performed. In this case, there is no problem that the aperture ratio is reduced.

In order to further improve the aperture ratio, TF
The above-mentioned Al8 is formed on T4 or source wiring 3 via an insulating film.
A film having a high reflection efficiency such as that described above may be formed as the pixel electrode 6 (electrically connected to the drain electrode). However, in this case, it is necessary to appropriately consider the thickness of the insulating film and the material used for the insulating film so that no parasitic capacitance occurs between the pixel electrode 6 and the TFT 4 or the source wiring 3. For example, IT
After forming O7, an organic insulating film having a dielectric constant of about 3.6 is deposited on the entire surface of the substrate so as to have a thickness of about 3 μm.
8 may be formed so as to overlap in the pixel and on the TFT 4 or the source wiring 3, and Al 8 may be electrically connected to the drain electrode 5. As a connection method, there is a method of forming a contact hole on the drain electrode 5 or the ITO 7 and making a connection via this.

In the present embodiment, the portion where the pixel electrode 6 is formed is divided into two regions, a region having high transmission efficiency and a region having high reflection efficiency. However, the invention is not limited to this. It may be. That is, as shown in FIG. 7, even if the pixel electrode 6 is divided into three regions A and B having high transmission efficiency and reflection efficiency and a region C having different transmission efficiency or reflection efficiency. Good.

Embodiment 4 Hereinafter, Embodiment 4 will be described with reference to the drawings. FIG. 8 is a partial plan view of an active matrix substrate in the liquid crystal display device of the present embodiment, and FIGS. 9A to 9D show a method of manufacturing the liquid crystal display device of the present embodiment. It corresponds to a cross section.

In this embodiment, a layer having high reflection efficiency is formed of the same material as the source wiring in the region B having high reflection efficiency. Note that the same reference numerals as those in the first to third embodiments are used for reference numerals in the drawings. In addition, pixels and TF
The configuration and manufacturing process of T are the same as those in the first to third embodiments unless otherwise specified.

When observing the active matrix substrate of the liquid crystal display device of the present embodiment from above, as shown in FIG. 8, a region A having high transmission efficiency is provided in the center of the pixel.
A band-shaped area B surrounding the area is provided. The outline of the region B is a square along the edges of the gate wiring and the source wiring. The region B is provided with a layer having a high reflection efficiency formed of the same material as the source wiring material, thereby increasing the reflection efficiency.

This manufacturing method will be described below. FIG.
As shown in FIG. 1A, a gate wiring (not shown), a gate electrode 10, a gate insulating film 9, a semiconductor layer 12, a channel protective layer 13, and n ⁺ -Si serving as source / drain electrodes are formed on an insulating substrate 1. The layer 11 is formed in order. Further, a conductive film 41 constituting a source wiring (shown in FIG. 8) is deposited by a sputtering method.

Subsequently, as shown in FIG. 9B, the conductive film 41 is patterned to form a layer 42 having high reflection efficiency, a drain-pixel electrode connection layer 43, and a source line 3. The portion where the layer 42 having high reflection efficiency is formed corresponds to the region B. Further, as shown in FIG. 9C, an interlayer insulating film 44 is formed, and subsequently, a contact hole 45 penetrating through the interlayer insulating film 44 is formed.

Next, as shown in FIG. 9D, ITO was formed as a layer 46 having high transmission efficiency over the entire area of each pixel.
It should be noted that the layer 46 having a high transmission efficiency may be made of a material having a high transmission efficiency, instead of ITO. A layer 46 having high transmission efficiency is formed in a contact hole 45 penetrating the interlayer insulating film 44.
Is electrically connected to the drain electrode 5 by being connected to the connection layer 43 through the gate. Further, the layer 46 with high transmission efficiency functions as a pixel electrode for applying a voltage to the liquid crystal layer, and a voltage is applied to the liquid crystal layer in any of the regions A and B by the layer 46 with high transmission efficiency. I have. Therefore, in the present embodiment, as compared with the case where the pixel electrode is formed by the layer having the high transmission efficiency in the region A and the layer having the high reflection efficiency in the region B, the pixel electrode is formed only by the layer 46 having the high transmission efficiency. Therefore, as compared with a transmissive liquid crystal display device, there is an advantage that a region having high reflection efficiency can be formed without an increase in the number of processes, and a defective pixel electrode is hardly formed.

Embodiment 5 Hereinafter, Embodiment 5 will be described with reference to the drawings. FIG. 10 is a partial plan view of an active matrix substrate in the liquid crystal display device of the present embodiment, and FIGS. 11A to 11D show a method of manufacturing the liquid crystal display device of the present embodiment. It corresponds to a cross section.

In the present embodiment, a layer having a high reflection efficiency is formed of the same material as that of the gate wiring in a region B having a high reflection efficiency (shaded portion in FIG. 10). Note that the same reference numerals as those in the first to fourth embodiments are used for reference numerals in the drawings. The configurations and manufacturing processes of the pixels and TFTs are the same as in the first to fourth embodiments unless otherwise specified.

In FIG. 10, when the active matrix substrate of the liquid crystal display device of this embodiment is observed from above,
An area A having high transmission efficiency is provided in the center of the pixel in a rectangular shape, and a band-shaped area B surrounding the area A is provided.
The outline of the region B is a square along the edges of the gate wiring and the source wiring. The region B is provided with a layer having a high reflection efficiency formed of the same material as the gate wiring material, thereby increasing the reflection efficiency.

A method for manufacturing this liquid crystal display device will be described below. First, as shown in FIG.
A conductive film is deposited thereon. Subsequently, the gate electrode 10, the gate wiring (shown in FIG. 10), and the layer 42 having high reflection efficiency are formed by patterning the conductive film. The area where the layer 42 having high reflection efficiency is formed is the area B
Is equivalent to

Next, as shown in FIG. 11B, a gate insulating film 9, a semiconductor layer 12, a channel protective layer 13, and an n ⁺ -Si layer 11 serving as source / drain electrodes are formed in this order. Further, a metal layer 3b which becomes a part of the source wiring 3,
The drain-pixel electrode connection layer 43 is formed by the same process. The connection layer 43 partially overlaps the drain electrode 5 of the TFT 4.

Further, as shown in FIG.
Is formed by a sputtering method, and is patterned as a layer 46 having a high transmission efficiency and an ITO layer 3 a to be a part of the source wiring 3. The layer 46 having a high transmission efficiency is formed in the whole area in each pixel, and the ITO layer 3a is patterned on the metal layer 3b so as to have the same shape as the metal layer 3b. The layer 46 having high transmission efficiency is electrically connected to the TFT 4 by partially overlapping the connection layer 43.

Next, as shown in FIG. 11D, a passivation film 47 is formed and patterned.

As described above, the region A having high transmission efficiency is provided in the central portion in the pixel, and the band-shaped region B having high reflection efficiency is provided along the edge of the source wiring. In this case, since the ITO layer 3a of the source wiring and the layer 42 having high reflection efficiency, which is a part of the pixel region, exist in different layers, the regions A and B have opposite patterns (the central portion). Is in the region with high reflection efficiency).
Since the distance between the layer 3a and the layer 42 having high reflection efficiency for preventing leakage can be further reduced, the aperture ratio of the pixel electrode can be improved.

Also, in the present embodiment, as in Embodiment 4, the pixel electrode is formed by only one type of electrode (the layer 46 having high transmission efficiency), so that the pixel electrode is formed by two types of electrodes. It is possible to produce efficiently with less occurrence of defects.

In this embodiment, since the source wiring 3 has a two-layer structure of the metal layer 3b and the ITO layer 3a,
Even if there is a film defect in a part of the metal layer 3b, the IT
The source wiring 3 is electrically connected by the O layer 3a.
There is an advantage that disconnection can be reduced.

(Embodiment 6) Hereinafter, Embodiment 6 will be described with reference to the drawings. FIG. 12 is a partial plan view of an active matrix substrate in the liquid crystal display device of the present embodiment, and FIGS. 13A to 13C show a method of manufacturing the liquid crystal display device of the present embodiment. It corresponds to a cross section.

In the present embodiment, a pixel electrode is formed on a gate wiring or a source wiring via an insulating film.
It is possible to improve the effective pixel area (the area that substantially functions as a pixel). Note that the same reference numerals as those in Embodiments 1 to 5 are used for reference numerals in the drawings. The configurations and manufacturing processes of the pixels and TFTs are the same as in the first to fifth embodiments unless otherwise specified.

First, in FIG. 12, when observing the active matrix substrate of the liquid crystal display device of the present embodiment from above, a region A having a high transmission efficiency is provided in the center of the pixel, and a band having a reflection efficiency having a band shape surrounds the region A. High region B (FIG. 1)
2 (hatched portion). The pixel electrode made of a layer having high transmission efficiency is superimposed on the gate wiring and the source wiring via an interlayer insulating film, and a voltage is also applied to the liquid crystal layer on the gate wiring 2 and the source wiring 3. It is possible to increase the effective pixel area as compared with the mode.
In this configuration, the gate wiring 2 and the source wiring 3 function as layers having high reflection efficiency in the region B.

This manufacturing method will be described below. FIG.
As shown in (a), a gate electrode 10 is formed on an insulating substrate 1.
And gate wiring 2 (shown in FIG. 12), gate insulating film 9,
A semiconductor layer 12, a channel protection layer 13, an n ⁺ -Si layer 11 serving as a source / drain electrode, and a source wiring 3 are sequentially formed. Note that, of the gate wiring 2 or the source wiring 3 formed here, it is preferable to use a material having high reflection efficiency at least in a portion to be overlapped with a light transmitting layer serving as a pixel electrode in a later step.

Next, as shown in FIG. 13B, an interlayer insulating film 44 is formed, and subsequently, a contact hole 45 penetrating the interlayer insulating film 44 is formed. Subsequently, FIG.
As shown in (1), a layer 46 having a high transmission efficiency made of a material having a high transmission efficiency such as ITO is formed by sputtering and patterned. The layer 46 having high transmission efficiency is connected to the connection layer 43 connected to the drain electrode 5 of the TFT 4 via a contact hole 45 penetrating the interlayer insulating film 44. Here, the layer 46 with high transmission efficiency is patterned so as to overlap at least one of the gate wiring 2 and the source wiring 3, so that the layer 46 with high transmission efficiency and the interlayer insulating film 44 are formed.
Gate wiring 2 or source wiring 3 overlapping via
Can be used as a layer having high reflection efficiency.

In this configuration, it is necessary to design a panel so that image quality deterioration such as crosstalk does not occur due to the capacitance generated between the layer 46 having high transmission efficiency, the gate wiring 2 and the source wiring 3.

As described above, in the present embodiment, when the region A with high transmission efficiency is provided in the center of the pixel and the region B with high reflection efficiency is formed along the edge of the gate wiring or the source wiring, It is not necessary to newly provide a region having high reflection efficiency, and the process can be shortened.

(Embodiment 7) Hereinafter, Embodiment 7 will be described with reference to the drawings. FIG. 14 is a partial plan view of the active matrix substrate in the liquid crystal display device of the present embodiment, and FIGS. 15 (a) to (c) and FIG. 16 (a).
14C are cross-sectional views illustrating a method for manufacturing the liquid crystal display device of the present embodiment, and correspond to a GG cross section in FIG.

As shown in FIG. 14, a region A having a high transmission efficiency is provided in the center of the pixel, and a band-like region B (a hatched portion in the drawing) having a high reflection efficiency is provided along the edge of the source line 3. Have been.

In this region B, high protrusions (53a in FIG. 16) randomly formed on the insulating substrate 1.
) And a low-height projection (shown at 53b in FIG. 16).
And the polymer resin formed on these projections (FIG. 16)
And a layer having a high reflection efficiency (shown at 42 in FIG. 16) is formed so as to cover this. As a result, the surface layer of the region B having a high reflection efficiency, which is a surface layer, has a continuous wavy surface, and is electrically connected to the drain electrode 5 via the contact hole 45 and the base electrode (not shown). ing.

Next, a method of manufacturing this liquid crystal display device will be described with reference to FIG.
5 (a) to 5 (c) and FIGS. 16 (a) to 16 (c). First, as shown in FIG. 15A, a plurality of gate wirings 2 made of Cr, Ta, etc. are formed on an insulating substrate 1.
(Shown in FIG. 14), and a gate electrode 10 branched from the gate wiring 2 is formed.

Then, covering the gate wiring 2 and the gate electrode 10, the entire surface of the insulating substrate 1 is covered with SiN.
A gate insulating film 9 made of x, SiOx or the like is formed, and a semiconductor layer 12 made of amorphous silicon (a-Si), polycrystalline silicon, CdSe, or the like is formed on the gate insulating film 9 above the gate electrode 10. Form. Then, the semiconductor layer 12
Are formed on the channel protection layer 13 at both ends of the contact layer 48 made of amorphous silicon (a-Si) or the like.

A contact electrode 49 made of Ti, Mo, Al, or the like is formed on one side of the contact layer 48 so as to overlap therewith.
A drain electrode 5 made of o, Al, or the like is formed so as to overlap.
In the seventh embodiment, as the insulating substrate 1, for example, a product of Corning Co., Ltd., trade name 7059, having a thickness of 1.1 mm
Glass plate can be used.

Next, as shown in FIG. 15B, a conductive film is formed by sputtering and patterned to form a base electrode 50 at the same time as the metal layer 3b to be a part of the source wiring. At this time, the auxiliary capacitance can be formed by forming a part of the base electrode 50, which is not shown, so as to overlap with the next-stage gate wiring 2 with the gate insulating film 9 interposed therebetween.

At this time, a layer having high reflection efficiency may be overlaid on a region on the gate wiring forming the storage capacitor, or
The aperture ratio can be further improved by forming a pixel region (region B) by increasing the reflection efficiency of the gate wiring itself or the like.

Subsequently, as shown in FIG. 15C, the ITO layer 3 forming the source wiring 3 together with the metal layer 3b is formed.
a was formed by sputtering and patterned. In the seventh embodiment, the layer constituting the source wiring 3 has a two-layer structure of the metal layer 3b and the ITO layer 3a. In this structure, even if a part of the metal layer 3b constituting the source wiring 3 has a defect in the film, it is electrically connected by the ITO layer 3a, so that disconnection of the source wiring 3 can be reduced. There is an advantage.

Further, in this step, simultaneously with the formation of the ITO layer 3a, the layer 46 having high transmission efficiency constituting the pixel electrode was patterned. In this manner, a layer 46 having high transmission efficiency as a pixel electrode can be formed simultaneously with the formation of the source wiring 3.

Next, as shown in FIG. 16A, a resist film 52 made of a photosensitive resin is formed and patterned, and is subjected to a heat treatment or the like to be squared off, so that a part thereof has a substantially circular cross section. The convex portions 53a having a high height and the convex portions 53b having a low height are formed in portions corresponding to the region B. At this time, the projections 53a and 53a are placed on the layer 46 having high transmission efficiency in order to efficiently apply a voltage to the liquid crystal layer.
It is preferable not to form b, but even if it is formed, if it is transparent, it will not have a significant optical effect.

Next, as shown in FIG.
A polymer film 54 is formed along 3a and 53b.
By this step, the uneven surface in the region B can be made a smoother shape with few flat portions. However, this step can be omitted by changing the manufacturing conditions.

Subsequently, as shown in FIG. 16C, a layer 42 having high reflection efficiency made of Al as a pixel electrode was formed at a predetermined position on the polymer film 54 by, for example, a sputtering method. . As a material suitable for use as the layer 42 having a high reflection efficiency, in addition to Al and an Al alloy, for example, Ta, Ni, Cr, Ag, or the like having a high reflection efficiency can be given. Is suitably about 0.01 to 1.0 μm.

As described above, according to the present embodiment, the region A having high transmission efficiency is formed in the center of the pixel, and the region B having high reflection efficiency is formed along the source wiring. In such a shape, since the ITO layer 3a of the source wiring and the layer 42 with high reflection efficiency which is a part of the pixel region exist in different layers, the reverse pattern (the center is a region with high reflection efficiency). Compared with the case, the intervals provided for preventing the leakage can be narrowed, and the aperture ratio of the pixel electrode can be improved.

In the present embodiment, the surface of the layer 42 having a high reflection efficiency has a smooth uneven structure in order to scatter the reflected light in a wide range. The surface of the layer 42 having high reflection efficiency may be flat without being formed. In any case, the layer 42 having a high reflection efficiency and the layer 46 having a high transmission efficiency constituting the pixel electrode exist as separate layers with a third substance (eg, resin, metal such as Mo) interposed therebetween. In this way, when using ITO as a material for a layer having high transmission efficiency, and using Al or an alloy thereof as a material for a layer having high reflection efficiency corresponding to the pattern of the region B, an electrode which is likely to be generated in the Al etching step. It is possible to reduce poor patterning of Al caused by an erosion reaction.

(Eighth Embodiment) Hereinafter, an eighth embodiment will be described with reference to the drawings. FIG. 17 is a plan view of one pixel portion of the active matrix substrate of the liquid crystal display device according to the eighth embodiment. FIG. 18 is a diagram showing a cross-sectional structure of the liquid crystal display device of the present embodiment, and corresponds to a cross section taken along line HH of FIG.

In FIGS. 17 and 18, pixel electrodes 6 are provided in a matrix on the active matrix substrate, and gates for supplying scanning signals are provided so as to pass around the pixel electrodes 6 and to be orthogonal to each other. A wiring 2 and a source wiring 3 for supplying a display signal are provided.
Part of the gate line 2 and the source line 3 is a pixel electrode 6.
And an outer peripheral portion thereof overlapped with an interlayer insulating film 44 interposed therebetween. Further, the gate wiring 2 and the source wiring 3 are formed of a metal film.

Further, a TFT 4 as a switching element for supplying a display signal to the pixel electrode 6 is provided near the intersection of the gate line 2 and the source line 3. The gate wiring 2 is connected to the gate electrode 10 of the TFT 4.
Is drive-controlled. The source wiring 3 is connected to the source electrode 49 of the TFT 4, and a data signal is input to the source electrode 49. Further, a connection electrode 55 is connected to the drain electrode 5 of the TFT 4, and is further electrically connected to the pixel electrode 6 via the contact hole 45.

The connection electrode 55 forms an auxiliary capacitance with the common wiring 15 via the gate insulating film 9.
The common wiring 15 is formed of a metal film, and is connected to a counter electrode formed on the counter substrate 56 by a wiring (not shown). If the common wiring 15 is formed in the same step as the gate wiring 2, the process can be shortened.

The pixel electrode 6 is composed of a layer 42 of high reflection efficiency made of Al or an Al-based alloy and a layer 46 of high transmission efficiency made of ITO. This pixel electrode 6
Observed from the top, there is a region A with high transmission efficiency and a region B with high reflection efficiency (corresponding to the hatched portion in FIG. 17). However, the layer 42 with high reflection efficiency may be a conductive metal layer with high reflection efficiency, such as Ta, as in the other embodiments.

Here, the region B is designed so as to cover a part of a light-shielding electrode such as the gate wiring 2, the source wiring 3, the TFT 4, the common wiring 15 and the like which does not transmit backlight light and a part of the wiring part. . With this structure, a region that cannot be used as the region A can be used as the region B having high reflection efficiency, so that the aperture ratio can be improved. The region A is formed so as to be surrounded by the region B.

As described above, the active matrix substrate of the eighth embodiment is configured, and can be manufactured as follows.

First, a gate electrode 10, a gate wiring 2, a common wiring 15, a gate insulating film 9, a semiconductor layer 12, a channel protection layer 13, a source electrode 49 and a drain electrode 5 are formed on a transparent insulating substrate 1 such as glass. It is formed by sequentially forming a film. Next, a transparent conductive film and a metal film forming the source wiring 3 and the connection electrode 55 are formed by lamination by sputtering and patterned into a predetermined shape.

The source wiring 3 is composed of an ITO layer 3a and a metal layer 3b.
Even if there is a defect such as a disconnection in a part of the metal layer 3b, the metal layer 3b is electrically connected by the ITO layer 3a, so that the disconnection of the source wiring 3 can be reduced.

Further, a photosensitive acrylic resin is formed thereon as an interlayer insulating film 44 to a thickness of 3 μm by a spin coating method. The acrylic resin is exposed according to a desired pattern and is developed with an alkaline solution. As a result, only the exposed portion is etched by the alkaline solution to form a contact hole 45 penetrating through the interlayer insulating film 44. In the formation of the contact hole 45 by the alkali development, the tapered shape of the contact hole 45 was also good.

As described above, by using a photosensitive acrylic resin as the interlayer insulating film 44, the thin film can be formed by the spin coating method, so that a thin film having a thickness of several μm can be easily formed. The patterning of the interlayer insulating film 44 is advantageous in terms of productivity such that a photoresist coating step is not required.

The acrylic resin used in the present embodiment is colored and can be made transparent by subjecting the entire surface thereof to an exposure treatment after patterning. The above-mentioned transparency treatment can also be performed chemically, and it goes without saying that it may be used.

Thereafter, the layer 4 having high transmission efficiency of the pixel electrode 6 is formed.
6 is formed by sputtering and patterned. Thereby, the layer 4 having high transmission efficiency, which is the pixel electrode 6
6 is electrically connected to a connection electrode 55 via a contact hole 45 penetrating through the interlayer insulating film 44.

Next, the gate wiring 2, the source wiring 3, the TFT
A layer 42 having high reflection efficiency made of Al or an Al-based alloy corresponding to the region B is formed on the layer 46 having high transmission efficiency so as to overlap with the common wiring 4 and the common wiring 15, and both layers are electrically connected. The adjacent pixel electrodes 6 are separated from each other on the gate wiring 2 and the source wiring 3 so as not to be electrically connected.

Thus, the active matrix substrate of this embodiment can be manufactured. In addition, as shown in FIG.
And a liquid crystal is sealed in these gaps to complete a liquid crystal display device.

As described above, in the liquid crystal display device according to the eighth embodiment, the layer 42 having high reflection efficiency is provided on the portion corresponding to the region B of the pixel electrode 6 on the TFT 4, the gate wiring 2, and the source electrode 3. A light-shielding film is provided to prevent light from entering the TFT 4 and to shield pixel electrodes on a gate line, a source line, and a common line, which are likely to cause light leakage in a display area such as a domain or a disclination line. There is no necessity, and a region which could not be used as a display region because a light-shielding film was conventionally provided and shielded light can be used as a display region of a pixel electrode, so that a display region of a liquid crystal panel is effectively used. be able to.

Further, when the gate wiring and the source wiring are formed of a metal film, these wirings have conventionally been unable to be used as a display area in a transmissive display device because they block backlight light. However, in the present embodiment,
A region A with high transmission efficiency is provided at the center of the pixel (two places in this embodiment), and a band-like region B with high reflection efficiency is provided so as to surround the region A. Therefore, a region B having high reflection efficiency can be formed above the gate wiring, the source wiring, the common wiring, and the switching element, and this can be used as a reflection region of the pixel electrode. The aperture ratio of the pixel electrode can be improved as compared with the case where the pattern surrounds the region B).

By providing the connection electrode 55 in the area B indicated by oblique lines as shown in FIG. 19, it is possible to suppress a decrease in the luminance of the transmitted light in the area A.

(Embodiment 9) Hereinafter, Embodiment 9 will be described with reference to the drawings. FIG. 20 is a partial plan view of a substrate in the simple matrix type liquid crystal display device of the present embodiment, and FIGS. 20 (b) and 20 (c) show FIG.
It is CC sectional drawing of (a).

In FIG. 20, a plurality of stripe-shaped electrodes 20 are arranged on a pair of transparent insulating substrates made of glass or plastic so as to be orthogonal to each other.
These intersecting regions are pixels 6. The portion where the pixel 6 is formed is, when observed from above the substrate,
It consists of two regions, a region A with high transmission efficiency and a region B with high reflection efficiency. In the present embodiment, ITO7 (Indium Ti
n Oxide) is provided, and a layer 8 having a two-layer structure of Al and Mo as a layer having high reflection efficiency is provided so as to cover the periphery thereof.

Then, although not shown, an alignment film is coated on the above-mentioned substrates, these paired substrates are bonded together so that the stripe-shaped electrodes 20 are orthogonally crossed, and liquid crystal is sealed between these substrates. By installing a backlight behind, the liquid crystal display device of the present embodiment is completed. In addition,
When a color display is desired, this can be realized by disposing a color filter composed of a colored layer of red, green, blue or the like in front of the liquid crystal layer.

Hereinafter, referring to FIGS. 20 (a) to 20 (c),
A method for manufacturing the simple matrix type liquid crystal display device of the present embodiment will be briefly described. As shown in FIG.
ITO as a striped electrode 20 on the insulating substrate 1
The layer 3a (lower layer) and the metal layer 3b (upper layer) are respectively formed by sputtering in order, and then patterned.
In this embodiment, a region A having a high transmission efficiency and a region B having a high reflection efficiency are formed by using ITO 7 and Al 8 as the electrode 20.

If the thickness of Al is 100 nm or more, a sufficiently stable reflection efficiency (about 90%) can be obtained, but in the present embodiment, the thickness of Al is 100 nm.
The thickness of m and Mo is 50 nm, the reflection efficiency is 90%, and ambient light can be effectively reflected. As a material having a high reflection efficiency, a metal such as Ag, Ta or W may be used in addition to Al or an Al-based alloy.

As described above, in the present embodiment, the region B having high reflection efficiency and the region A having high transmission efficiency are provided as the stripe-shaped electrodes 20, so that the liquid crystal display device using the conventional transflective film is used. Thus, a liquid crystal display device capable of performing transmissive display, reflective display, or both types of display while using ambient light or illumination light without loss is realized.

In FIG. 20B, as the electrode 20, Al is formed inside the pixel 6 so as to overlap with ITO, and ITO is formed in the center of the pixel. As described above, since ITO and Al are electrically connected,
There is no such a problem that a disclination line occurs due to a partially different alignment state of liquid crystal in the same pixel when a voltage is applied.

When a liquid crystal display device is manufactured using the substrate shown in FIG. 20C and the counter substrate 23 on which the counter electrode 22 is formed, as shown in FIG. Cell thickness dt of the liquid crystal layer 24 corresponding to the region B, and the cell thickness dr of the liquid crystal layer 24 corresponding to the region B having a high reflection efficiency.
Differs by the amount of the insulating layer. Utilizing this, it is possible to obtain consistency between the optical characteristics of both modes. For example, dt>
When a liquid crystal display device is manufactured so as to achieve dr, the optical path lengths of both modes can be made closer, so that good display can be obtained. Furthermore, when the liquid crystal display device is manufactured while adjusting the thickness of the insulating layer and the spacers indicating the two substrates so that dt = 2dr, if the voltage supply state is the same, the electro-optical characteristics of the two are adjusted. Since the matching of the characteristics is further improved, and the brightness and the contrast are uniform in both modes, a better display can be obtained.

Here, a 8.4-inch diagonal liquid crystal display device provided with a region A having a high transmission efficiency and a region B having a high reflection efficiency was manufactured, and the transmitted light by the backlight and the reflection by the external light were manufactured. FIG. 22 shows the results of evaluating the characteristics of 64-gradation display with light. The measurement of transmitted light by external light was performed by using BM-5 manufactured by Topcon, and the measurement of reflected light by external light was performed by using LCD-5000 manufactured by Otsuka Electronics. At this time, the backlight is used as a light source in the BM-5 made by Topcon, an integrating sphere is used as an external light source in the LCD-5000 made by Otsuka Electronics, and the light taking-in angle is perpendicular to the substrate surface of the liquid crystal display device. The measurement was performed so that

In this liquid crystal display device, the ratio of the area A having high transmission efficiency and the area B having high reflection efficiency to the pixel is about 4%.
The area A having a high transmission efficiency was formed of ITO, and the area B having a high reflection efficiency was formed of Al. The cell thickness of the region A having a high transmission efficiency was set to about 3 μm, while the cell thickness of the region A having a high transmission efficiency was set to about 5.5 μm. This is to make the optical path length of the transmitted light by the light from the backlight and the optical path length of the reflected light by the external light as close as possible. As shown in FIG. 22, in the region A where the transmission efficiency is high, the transmittance / reflectance of 64-gradation display of the transmitted light due to the light from the backlight and the reflected light due to the external light are almost the same. Sufficient display quality can be obtained when displaying by simultaneously using both the transmitted light due to the light and the reflected light due to the external light. The contrast ratio at this time is
About 200 in transmitted light by light from the backlight,
About 25 was obtained in the reflected light by external light.

FIG. 23 shows the color reproducibility of a conventional 8.4-inch diagonal transmissive liquid crystal display device. FIG. 24 shows a region 8.4-inch diagonally high transmission efficiency A in this embodiment.
4 shows the color reproducibility of a liquid crystal display device provided with a region B having high reflection efficiency. As shown in FIG. 23, in the conventional liquid crystal display device, the panel illuminance of external light is 800 (lx), 1700 (l
The color gamut is significantly reduced as x) increases.
However, as shown in FIG. 24, in the liquid crystal display device according to the present embodiment, the panel illuminance of the external light is 800 (l).
x) Even if it is increased to 1700 (lx), the color gamut is hardly reduced. This is because, in the conventional liquid crystal display device, the contrast is lowered due to surface reflection of external light on the surface of the liquid crystal display device or light reflected from a light blocking black mask bus line or the like. On the other hand, the liquid crystal display device according to the present embodiment performs display in the reflection region using external light. Does not cause a decrease in contrast in the reflection area. for that reason,
In the liquid crystal display device provided with the region A having a high transmission efficiency and the region B having a high reflection efficiency in the present embodiment, no matter how much the panel illuminance of the external light increases, the color reproduction range hardly decreases. It is possible to perform a display with high visibility even in such an environment.

As in the present embodiment, a liquid crystal display device provided with a region having a high transmission efficiency and a region having a high reflection efficiency changes the direction of the screen or moves to an environment where it is easy to see for the convenience of the user. It is particularly effective to mount it on products that cannot be used.

Note that the features of the liquid crystal display device according to the present embodiment are the same even when the liquid crystal display device is manufactured using the substrate shown in FIG. 16C described in the seventh embodiment. The effect of is obtained.

Further, in this embodiment, good display characteristics could be obtained by setting the area ratio between the region A and the region B to 60:40. The area ratio is not limited to this value, and may be appropriately changed according to the transmission efficiency or the reflection efficiency of the regions A and B and the purpose of use.

In the present invention, the area ratio of the area B is preferably 10 to 90% with respect to the effective pixel area (the area obtained by adding the area A and the area B). When this ratio is less than 10%, that is, when the ratio of the area with high transmission efficiency to the pixels is too high, the external light is too bright and the display is fuzzy. The same problem occurs. Conversely, area B
When the area ratio exceeds 90%, the ratio of the area A is low even when the backlight is turned on and displayed when the ambient light becomes dark enough that the display cannot be observed only with the ambient light. The display is too hard to see.

In particular, when the product is mounted in a product type in which the main use environment is outdoors, it is necessary to attach importance to the battery life, and the design is made such that the power consumption is prioritized and the external light can be used efficiently. There must be. Therefore,
It is desirable that the ratio of the region B having high reflection efficiency is 40 to 90%. Here, if the area ratio of the region B is 40%, the environment in which the display can be performed only by the reflection type is very limited, and the time when the backlight must be turned on becomes long, so that the battery life is shortened.

On the other hand, when mounted in a product form in which the main use environment is indoors, the design is such that the backlight light is efficiently used. Therefore, the ratio of the area B is 1
0 to 60% is desirable. If the area ratio of the area B exceeds 60%, the area of the area A through which the backlight transmits is small, and the brightness of the backlight needs to be significantly higher than that of, for example, a transmissive liquid crystal display device. The power is increased, and the efficiency of use of the backlight is reduced.

In the above-described embodiment, when the substrate is observed from above, a region A having a high transmission efficiency is provided in the center of the pixel, and a region B having a high reflection efficiency is provided so as to surround the region A. However, the present invention is not limited to this configuration. For example, FIG.
As shown in (a) to (c), even in a configuration in which a region B with high reflection efficiency is provided in the central portion in the pixel and a region A with high transmission efficiency surrounding the region B is provided. I do not care. Such a simple matrix type liquid crystal display device can also be manufactured by the same method as in the above-described embodiment.

Embodiment 10 Hereinafter, embodiment 10 will be described with reference to the drawings. FIG. 26A is a partial plan view of a substrate in the simple matrix type liquid crystal display device of the present embodiment, and FIG. 26B and FIG.
FIG. 27C is a cross-sectional view taken along the line CC of FIG.

In this embodiment, when the portion where the stripe-shaped electrodes 20 are formed is observed from above, the region A having high transmission efficiency and the region B having high reflection efficiency are divided at the vicinity of the pixel center. Shape. The reference numerals in the drawing are the same as in the ninth embodiment.
The configuration and manufacturing process of the pixel are the same as those in the ninth embodiment unless otherwise specified.

As shown in FIG. 26, in this embodiment, an ITO 7 having a high transmission efficiency is provided so as to be divided from the vicinity of a central portion in a pixel, and a layer 8 having a two-layer structure of Al and Mo is provided in the pixel. Superimposed on the ITO7 at the center,
Is provided on the opposite side.

As described above, in the present embodiment, the region B having a high transmission efficiency and the region A having a high transmission efficiency are provided as the stripe-shaped electrodes 20, so that the conventional liquid crystal display device using a semi-transmissive reflection film can be used. In comparison, a liquid crystal display device capable of performing transmissive display, reflective display, or both types of display while using ambient light or illumination light without loss is realized.

In FIG. 26B, the electrode 20 is divided from the vicinity of the center in the pixel 6 and Al is formed of ITO.
, And ITO is formed on the entire surface of the pixel 6. In FIG. 26 (c), ITO and A
1 is partially formed so as to partially overlap near the center of the pixel 6.

In the above-described embodiment, when the portion where the stripe-shaped electrode 20 is formed is observed from above, the region A having high transmission efficiency and the region B having high reflection efficiency are bounded by the vicinity of the pixel center. Although the present invention has been described with respect to a configuration in which the electrode is divided into two, the present invention is not limited to this. For example, as shown in FIGS. An area B having high efficiency is provided, and areas A having high transmission efficiency are provided on both sides to cover the area B.
May be provided. Such a simple matrix type liquid crystal display device can also be manufactured by the same method as in the above-described embodiment.

As described above, Embodiment 1 of the liquid crystal display device of the present invention
8 have been described, and the differences between the present invention and the conventional reflective liquid crystal display device or conventional transmissive liquid crystal display device will be further described below.

In the conventional reflection type liquid crystal display device, display is performed using ambient light for the purpose of low power consumption. Therefore, even if the ambient light is darker than a certain limit value even in an environment where sufficient power can be supplied. The display cannot be recognized.
This was the biggest drawback of the reflection type liquid crystal display.

In addition, if the reflection characteristics of the reflective electrode vary in the manufacturing process, the utilization efficiency of ambient light also varies, so that the ambient light intensity as a critical value at which display cannot be recognized varies between panels. Become. Therefore, at the time of manufacturing, a liquid crystal display device having stable display characteristics could not be obtained unless variation in the reflection characteristics was controlled more than variation in the aperture ratio in the conventional transmission type liquid crystal display device.

On the other hand, the liquid crystal display device of the present invention uses backlight light in an environment where sufficient power can be supplied, similarly to a conventional transmissive liquid crystal display device. Becomes possible. Therefore, the present invention has an advantage in that it is not necessary to control the variation in the utilization efficiency of the ambient light due to the variation in the reflection characteristic as precisely as in the reflection type liquid crystal display device.

On the other hand, in the conventional transmission type liquid crystal display device, when the ambient light becomes bright, the surface reflection component increases, so that it is easy to make display recognition difficult. On the other hand, the liquid crystal display device of the present invention has an advantage that the visibility is further improved because the panel luminance is increased by using the reflection area together with the brighter ambient light.

As described above, the liquid crystal display device of the present invention has the problem that the visibility is reduced due to surface reflection in an environment where ambient light is bright in the conventional transmission type liquid crystal display device, and the conventional reflection type liquid crystal display device does not. The present invention can simultaneously solve both of the problems that display observation becomes difficult due to a decrease in panel brightness in an environment where ambient light is dark, and also has both advantages.

[0146]

As described above in detail, according to the liquid crystal display device of the present invention, a region having a higher transmission efficiency and a region having a higher reflection efficiency than the transflective film are provided in each pixel. Since a layer having high transmission efficiency or a layer having high reflection efficiency functions as a pixel, the use efficiency of ambient light or illumination light is reduced due to, for example, a stray light phenomenon as in a conventional liquid crystal display device using a transflective film. Therefore, no matter what the brightness of the ambient light is, a good image can always be displayed as a reflective display, a transmissive display, or a dual-purpose display. In addition, since both the backlight and the ambient light can be simultaneously and efficiently contributed to the display, the amount of power consumption is significantly reduced as compared with a so-called transmissive liquid crystal display device that always uses only the backlight. It is possible to do.

That is, there is a drawback that the visibility is extremely reduced when the ambient light is dark, which is a problem with the conventional reflective liquid crystal display device, and the ambient light is very bright, which is a conventional transmissive liquid crystal display device. The disadvantage that the display becomes difficult to see in such a case can be solved at the same time by improving the light use efficiency by the present invention.

In addition, the region having high reflection efficiency covers any part of the gate wiring or the source wiring or the switching element, so that light incident on this part can also contribute to display. as a result,
The effective area of the pixel can be significantly improved.
In addition to solving the above-mentioned problems of the related art using the transflective film, the pixel aperture ratio can be improved even in comparison with a general transmissive liquid crystal display device.

Further, by forming a pixel electrode only with a layer having a high transmission efficiency, for example, a layer having a high transmission efficiency and a layer having a high reflection efficiency are electrically connected to each other so that a pixel electrode for one pixel is formed. In comparison with the case where a single pixel electrode is formed by overlapping a part of a layer having a high transmission efficiency and a layer having a high reflection efficiency with each other, it is possible to reduce the occurrence of defects due to the pixel electrode, The yield rate is improved.

Further, by using the same material for forming the region having high transmission efficiency or the region having high reflection efficiency and the material for forming the source wiring or the gate wiring, the manufacturing process of the liquid crystal display device is simplified.

Further, by setting the area ratio of the region having a high reflection efficiency to 10 to 90%, the ambient light is too bright and the display is obscured and becomes difficult to see. In addition, both problems of the conventional reflection type liquid crystal display device, which was impossible to observe at all when the ambient light intensity is extremely weak, are solved, and the reflection type display is performed regardless of the ambient light condition. As a result, an optimal display can be performed as a transmissive display or a dual-purpose display.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a plan view illustrating a liquid crystal display device according to a second embodiment of the present invention.

FIG. 4 is a sectional view taken along line BB of FIG. 3;

FIG. 5 is a plan view illustrating a liquid crystal display device according to a third embodiment of the present invention.

FIG. 6 is a sectional view taken along the line CC of FIG. 3;

FIG. 7 is a plan view showing a liquid crystal display device according to another embodiment of the present invention.

FIG. 8 is a plan view showing a liquid crystal display device according to Embodiment 4 of the present invention.

FIG. 9 is a sectional view taken along line DD of FIG. 8;

FIG. 10 is a plan view illustrating a liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 11 is a sectional view taken along line EE of FIG. 10;

FIG. 12 is a plan view showing a liquid crystal display device according to Embodiment 6 of the present invention.

13 is a sectional view taken along line FF of FIG.

FIG. 14 is a plan view showing a liquid crystal display device according to Embodiment 7 of the present invention.

15 is a diagram illustrating a method for manufacturing a liquid crystal display device corresponding to a section taken along line GG of FIG. 14;

16 is a diagram illustrating a method for manufacturing a liquid crystal display device corresponding to a section taken along line GG of FIG. 14;

FIG. 17 is a plan view illustrating a liquid crystal display device according to an eighth embodiment of the present invention.

18 is a sectional view taken along line HH of FIG.

FIG. 19 is a plan view showing another liquid crystal display device according to the eighth embodiment.

FIG. 20 is a view showing a simple matrix type liquid crystal display device according to a ninth embodiment.

FIG. 21 is a sectional view showing a simple matrix liquid crystal display device according to a ninth embodiment.

FIG. 22 is a view illustrating the characteristic evaluation of the liquid crystal display device according to the ninth embodiment.

FIG. 23 is a view showing the color reproducibility of the conventional transmissive liquid crystal display device used in the ninth embodiment.

FIG. 24 is a diagram illustrating the color reproducibility of the liquid crystal display device according to the ninth embodiment.

FIG. 25 is a view showing another simple matrix type liquid crystal display device according to the ninth embodiment.

FIG. 26 is a view showing a simple matrix type liquid crystal display device according to a tenth embodiment.

FIG. 27 is a view showing another simple matrix type liquid crystal display device according to the tenth embodiment.

FIG. 28 is a plan view showing a conventional liquid crystal display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Gate wiring 2a Next-stage gate wiring 3 Source wiring 3a ITO layer 3b Metal layer 4 TFT 5 Drain electrode 6, 38 Pixel electrode 7 ITO 8 Al or Al-based alloy 9 Gate insulating film 10 Gate electrode 11 n ⁺ - Si layer 12 Semiconductor layer 13 Channel protection layer 14 Mo 15 Common wiring 20 Stripe electrode 21 Insulation layer 22 Stripe counter electrode 23 Counter substrate 24 Liquid crystal layer 30 Polarizer 31 Phase difference plate 32 Transparent substrate 33 Black mask 34 Counter electrode 35 Alignment film 36 liquid crystal layer 37 MIM 39 light source 41 conductive film 42 layer with high reflection efficiency 43 (drain-pixel electrode) connection layer 44 interlayer insulation film 45 contact hole 46 layer with high transmission efficiency 47 passivation film 48 contact layer 49 source electrode 50 base electrode 52 resist film 53a High convex part 53b Low convex part 54 Passivation film 55 Connection electrode 56 Counter substrate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Shogo Fujioka, Inventor 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Atsushi Ban 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside (72) Inventor Naoyuki Shimada 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Sharp Corporation (72) Inventor Yoji Yoshimura 22-22, Nagaikecho, Abeno-ku, Osaka City, Osaka Sharp Corporation ( 72) Inventor Mikio Katayama 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka (72) Inventor Hiroshi Ishii 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 2H091 FA14Y FB08 FC02 FD04 FD06 GA03 GA07 GA13 HA08 KA04 KA10 LA03 LA18 2H092 JA26 JA27 JA40 JA44 JA45 JA46 JB04 JB05 JB07 JB56 JB57 KB13 KB25 MA05 M A12 NA25 PA12 QA08

Claims (6)

[Claims] 1. A liquid crystal display device comprising a plurality of pixels defined by a pair of electrodes for applying a voltage to said liquid crystal layer, wherein said liquid crystal layer is sandwiched between at least two substrates. , A region with high transmission efficiency and a region with high reflection efficiency are provided, and in each of them, a layer with high transmission efficiency or a layer with high reflection efficiency functions as a pixel electrode to improve light use efficiency. Liquid crystal display device. 2. The method according to claim 1, wherein the plurality of pixels are surrounded by a plurality of gate wirings formed on a substrate and a plurality of source wirings arranged orthogonal to the gate wirings. Item 2. The liquid crystal display device according to item 1. 3. The liquid crystal display device according to claim 2, wherein the region having a high reflection efficiency covers a part of the gate wiring or the source wiring or a part of the switching element. 4. The liquid crystal display according to claim 2, wherein the layer having high transmission efficiency or high reflection efficiency is formed of a material constituting either the gate wiring or the source wiring. apparatus. 5. The method according to claim 1, wherein only the layer having high transmission efficiency functions as a pixel electrode, and the layer having high reflection efficiency is electrically insulated from the layer having high transmission efficiency. 5. The liquid crystal display device according to any one of 1 to 4. 6. The liquid crystal display device according to claim 1, wherein an area ratio of the high reflection efficiency area to the pixel area is 10 to 90%.