JP2006146271A - Liquid crystal display device - Google Patents

Abstract

<P>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. <P>SOLUTION: In the liquid crystal display device which comprises a liquid crystal layer interposed between at least two sheets of substrates, and which is equipped with a plurality of pixels defined by a pair of electrodes to apply a voltage to the liquid crystal layer, a region A where transmission efficiency is high and a region B where reflection efficiency is high are arranged in each of the plurality of pixels. A layer 7 with high transmission efficiency or a layer 8 with high reflection efficiency functions as a pixel electrode 6 in each region. The layer 7 with high transmission efficiency is composed of ITO, and the layer 8 with high reflection efficiency is composed of Al or an Al based alloy. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device having a transmissive display area and a reflective display area.

  Liquid crystal display devices are widely used in OA devices such as word processors and personal computers, portable information devices such as electronic notebooks, or camera-integrated VTRs equipped with a liquid crystal monitor, taking advantage of the thin and low power consumption features. It is used.

  In addition, the liquid crystal display panel mounted on the liquid crystal display device does not emit light itself, unlike a CRT (brown tube) or EL (electroluminescence) display. Therefore, an illuminating device including a fluorescent tube called a backlight is provided on the back or side thereof. A so-called transmissive liquid crystal display device that is installed and displays an image by controlling the amount of transmission of backlight light with a liquid crystal display panel is often used.

  However, in the transmissive liquid crystal display device, the backlight usually occupies 50% or more of the total power consumption of the liquid crystal display device, so that the power consumption increases by providing the backlight.

  Therefore, apart from the transmissive liquid crystal display device, in a portable information device having many machines that are used outdoors and always carried, a reflector is installed on one substrate instead of the backlight, and ambient light is reflected on the reflector surface. Therefore, a reflection type liquid crystal display device that performs display is used.

  The display mode used in the reflective 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 the present transmissive liquid crystal display device, In recent years, a phase transition type guest-host mode that can realize bright display without using a plate has been actively developed.

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

  Therefore, in order to solve the above problems, as shown in Patent Document 1, conventionally, by using a transflective film that transmits part of light and reflects part of light, a transmissive display is achieved. A configuration is disclosed in which both reflective displays are realized by a single 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 34, an alignment film 35, a liquid crystal layer 36, an MIM 37, a pixel electrode 38, a light source 39, and a reflective film 40. Yes.

The pixel electrode 38, which is a semi-transmissive reflective film, is formed so that metal particles are deposited very thinly on the entire surface of the pixel, or are formed such that minute hole defects, indentation defects, etc. are scattered in the surface. By transmitting the light from the light source 39 through the pixel electrode 38 and reflecting the external light such as natural light or indoor illumination light by the pixel electrode 38, the transmissive display function and the reflective display function can be realized simultaneously.
JP 7-333598 A

  However, the display device shown in FIG. 28 has the following problems. First, when the above-described semi-transmissive reflective film is formed by depositing metal particles very thinly, the metal particles are a material having a large absorption coefficient, so that the internal absorption of incident light is large, and absorbed light that is not used for display is also present. As a result, the light utilization efficiency is poor. For example, even when 100% of light is incident, only 30% of light can be used for transmission and 15% for reflection.

  On the other hand, when a film having minute hole defects, indentation defects, or the like scattered in the surface is used as the pixel electrode 38, the structure of the film is so complicated that it is difficult to control because it involves precise design conditions in manufacturing. In addition, there is a problem that it is difficult to manufacture a film having uniform characteristics. In other words, the reproducibility of electrical characteristics and optical characteristics is poor, and it has been extremely difficult to control display quality as a liquid crystal display device.

  For example, in recent years, if a thin film transistor (TFT) generally used as a switching element of a liquid crystal display device is to be adopted in the above-described conventional technology, an electrode for forming an auxiliary capacitor in a pixel is formed by another electrode / wiring material. However, when a transflective film is used as the pixel electrode as in the prior art, there is a problem that it is not suitable for forming an auxiliary capacitor. Further, even when the pixel electrode is formed so as to cover these wirings and elements through the insulating layer, there is a problem that it is difficult to contribute to the improvement of the aperture ratio because the transmissive component coexists. Further, since light excitation current is generated when light is incident on the semiconductor layer of the switching element such as MIM or TFT, even if the semi-transmissive reflective film is used as the light shielding layer, it is necessary to provide a light shielding film on the opposite substrate side. It was.

  The present invention has been made to solve the above-described problems, and in a liquid crystal display device that realizes a transmissive display and a reflective display simultaneously on a single substrate, the ambient light and back light are higher than those of conventional liquid crystal display devices. An object of the present invention is to provide a liquid crystal display device that improves the light light utilization efficiency, stabilizes the quality, and simplifies the manufacture.

  The liquid crystal display device of the present invention is a liquid crystal display device comprising a plurality of pixels each having a liquid crystal layer held between at least two substrates and defined by a pair of electrodes for applying a voltage to the liquid crystal layer. Inside, a region having a high light transmission efficiency and a region having a high reflection efficiency are provided, and in each of the regions, a layer having a high light transmission efficiency or a layer having a high reflection efficiency functions as a pixel electrode, The layer having a high transmission efficiency is ITO, and the layer having a high reflection efficiency is Al or an Al-based alloy, thereby solving the above problem.

  The thickness of the layer having high reflection efficiency is suitably 0.01 to 1.0 μm. If the thickness is 100 nm or more, ambient light can be effectively reflected.

  The plurality of pixels are preferably surrounded by a plurality of gate wirings formed on the substrate and a plurality of source wirings arranged to be orthogonal to the gate wirings.

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

  The layer having high transmission efficiency or reflection efficiency is preferably formed of a material constituting either the gate wiring or the source wiring.

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

  More preferably, the area ratio of the region having high reflection efficiency in the pixel region (pixel region 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 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 high transmission efficiency or a layer having a high reflection efficiency functions as a pixel in each region. Therefore, unlike the conventional liquid crystal display device using a transflective film, the utilization efficiency of ambient light and illumination light does not decrease due to, for example, the stray light phenomenon. Furthermore, the electro-optical characteristics are different between the transmission mode in which the liquid crystal layer passes once and the reflection mode in which the liquid crystal layer passes twice. Therefore, in the present invention, a region having a high transmission efficiency and a region having a high reflection efficiency are clearly separated. For example, by changing the cell thickness of the liquid crystal layer, changing the applied voltage, changing the type of the retardation plate, etc. Both modes can be adjusted for consistency. Therefore, a good image can always be displayed as a reflective display, a transmissive display, or a combination of both, regardless of the brightness of the ambient light. In addition, since both the backlight light and the ambient light can be contributed to the display efficiently at the same time, the power consumption is remarkably compared with a so-called transmissive liquid crystal display device that always uses only strong backlight light. It becomes possible to decrease.

  That is, the conventional reflective liquid crystal display device has a drawback that the visibility is extremely lowered when the ambient light is dark, and the conventional reflective liquid crystal display device displays when the ambient light is very bright. Can be solved at the same time while improving the light use efficiency.

  In addition, a region having higher transmission efficiency and a region having higher reflection efficiency than the transflective film are provided in each pixel, and in each region, a layer having high transmission efficiency or a layer having high reflection efficiency functions as a pixel electrode. Regardless of the brightness of light, a good image can always be displayed as a reflective display, a transmissive display, or a combination of both. In addition, since both the backlight light and the ambient light can be contributed to the display efficiently at the same time, the power consumption is remarkably compared with a so-called transmissive liquid crystal display device that always uses only strong backlight light. It becomes possible to decrease.

  If the high reflective efficiency region covers any part of the gate wiring or source wiring, or the switching element, light incident on this part can also contribute to display, and as a result, The effective area of the pixel can be greatly improved. In addition to solving the above-described problems of the prior art using a transflective film, the pixel aperture ratio can be improved as compared with a general transmissive liquid crystal display device.

  If the material constituting the region having high transmission efficiency or the region having high reflection efficiency is the same as the material constituting the source wiring or the gate wiring, the manufacturing process of the liquid crystal display device is simplified.

  If the pixel electrode is composed of only a layer having a high transmission efficiency, for example, a pixel electrode for one pixel is formed by electrically connecting a layer having a high transmission efficiency and a layer having a high reflection efficiency. As compared with the case where one pixel electrode is formed by overlapping each part of the layer with high transmission efficiency and the layer with high reflection efficiency, the occurrence of defects due to the pixel electrode can be reduced, and the yield rate is improved.

  If the area ratio of the region having high reflection efficiency is set to 10 to 90%, the ambient light is too bright and the display is obscured and difficult to see. This solves both the problems of conventional reflective liquid crystal display devices that could not be observed at all when the light was extremely weak. As a dual-use type, it is possible to perform optimal display.

  According to the liquid crystal display device of the present invention, a region having higher transmission efficiency and a region having higher reflection efficiency than the transflective film are provided in each pixel, and a layer having high transmission efficiency or a layer having high reflection efficiency is provided in each region. Since it functions as a pixel, the use efficiency of ambient light and illumination light does not decrease due to, for example, stray light phenomenon as in a conventional liquid crystal display device using a transflective film, and the brightness of the ambient light is However, a good image can always be displayed as a reflective display, a transmissive display, or a dual-use display. In addition, since both backlight light and ambient light can be contributed to display efficiently at the same time, power consumption is significantly reduced compared to so-called transmissive liquid crystal display devices that always use only backlight light. It becomes possible to make it.

  That is, the conventional reflective liquid crystal display device has a drawback that the visibility is extremely lowered when the ambient light is dark, and the conventional reflective liquid crystal display device displays when the ambient light is very bright. Can be solved at the same time while improving the light use efficiency.

  Further, if the region having high reflection efficiency covers any part of the gate wiring, the source wiring, or the switching element, light incident on this part can also contribute to the display, and as a result, the pixel It is possible to significantly improve the effective area. In addition to solving the above-described problems of the prior art using a transflective film, the pixel aperture ratio can be improved as compared with a general transmissive liquid crystal display device.

  Further, if the pixel electrode is composed of only a layer with high transmission efficiency, for example, a pixel electrode for one pixel is formed by electrically connecting a layer with high transmission efficiency and a layer with high reflection efficiency. Compared to the case where one 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, occurrence of defects due to the pixel electrode can be reduced, and the yield rate is improved. To do.

  Further, if the material constituting the region having high transmission efficiency or the region having high reflection efficiency is the same as the material constituting the source wiring or the gate wiring, the manufacturing process of the liquid crystal display device is simplified.

  Furthermore, if the area ratio of the region having high reflection efficiency is set to 10 to 90%, the ambient light is too bright and the display is obscured and difficult to see. Both of the problems that existed in the conventional reflective liquid crystal display devices that could not be observed at all when the light intensity was extremely low were solved. Optimal display can be performed as a mold display or as a dual-use mold.

(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 this embodiment, and FIG. 2 is a cross-sectional view taken along line AA in FIG.

  In FIG. 1, a plurality of gate wirings 2 and a plurality of source wirings 3 are arranged on a transparent insulating substrate 1 made of glass, plastic, or the like so as to be orthogonal to each other. A TFT 4 is provided in the vicinity of the intersection. A pixel electrode 6 is connected to the drain electrode 5 of the TFT 4. The portion where the pixel electrode 6 is formed is composed of 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. As a high layer, ITO 7 (Indium Tin Oxide) is provided, and in the latter, Al or an Al-based alloy 8 is provided as a layer having a high reflection efficiency. Further, since the pixel electrode 6 is superimposed on the gate wiring 2a in the next stage via the gate insulating film 9, an auxiliary capacitance for driving the liquid crystal is generated in this portion during driving.

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

  Although not shown, an alignment 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 alignment film are formed, liquid crystal is sealed between the substrates, and a backlight is installed behind. Thus, the liquid crystal display device of this embodiment is completed.

  As the liquid crystal, guest host liquid crystal ZLI2327 mixed with black pigment mixed with 0.5% of optically active substance S-811 (manufactured by Merck) was used. In addition to this, as the liquid crystal mode, it is also possible to use an ECB mode by disposing polarizing plates above and below the liquid crystal layer. Further, when color display is desired, this can be realized by arranging a color filter composed of colored layers of red, green, blue, etc. in front of the liquid crystal layer.

Below, the manufacturing method of the active matrix substrate of this embodiment is demonstrated. First, the gate wiring 2 and the gate electrode 10 were formed on the insulating substrate 1 with Ta, and then the gate insulating film 9 was formed on the entire surface of the substrate. Subsequently, after forming the semiconductor layer 12 and the channel protective layer 13 on the gate electrode 10, the n ⁺ -Si layer 11 was formed as a source / drain electrode.

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

  Thus, since the source wiring 3 has a two-layer structure, even if there is a film defect in a part of the metal layer 3b constituting the source wiring 3, it is electrically connected by the ITO layer 3a. There is an advantage that disconnection failure of the source wiring 3 can be reduced.

  Further, in the pixel electrode 6 of the present embodiment, the region A having a high transmission efficiency formed of ITO 7 is formed by the same material and the same process as the ITO layer 3a of the source wiring 3. In the region B having a high reflection efficiency, Mo14 and Al8 were sequentially formed by sputtering, followed by patterning. If the thickness of Al is 150 nm or more, a sufficiently stable reflection efficiency (about 90%) can be obtained. However, in this embodiment, the thickness of Al is 150 nm, the reflection efficiency is 90%, and ambient light is effective. Can be reflected. In addition, as a material having high reflection efficiency, a metal such as Ag, Ta, or W may be used in addition to Al or an Al-based alloy.

  In the present embodiment, ITO 7 and Al 8 are used as the pixel electrode 6. However, the present invention is not limited to this. For example, a region having a high transmission efficiency and a region having a high reflection efficiency are formed by changing the thickness of Al or an Al alloy. The regions A and B may be used. With such a configuration, the manufacturing process can be simplified as compared with the case of using different materials. Alternatively, the metal layer 3b of the source wiring 3 and the material having high reflection efficiency (Al8 in the present embodiment) constituting the region B are made of the same material, so that the same manufacturing as that of the conventional transmissive liquid crystal display device is performed. It can be formed by a process.

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

  Further, as the pixel electrode 6, ITO is formed so as to overlap the entire area inside the pixel and the upper part of the next-stage gate wiring 2 a via the gate insulating film 9. In the region B, Al 8 is formed on the ITO 7 via Mo 14. An island is formed in the center of the pixel. Thus, since ITO 7 and Al 8 are electrically connected, the two regions A and B apply the same voltage to the liquid crystal by the same TFT 7. That is, when a voltage is applied, there is no inconvenience that a disclination line occurs because the alignment state of the liquid crystals is partially different within the same pixel.

  Moreover, by interposing Mo14 between ITO7 and Al8, it is possible to prevent the occurrence of electrolytic corrosion due to the contact between ITO7 and Al8 through the electrolytic solution in the manufacturing process.

  In the present embodiment, it is possible to obtain good display characteristics by setting the area ratio of 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 reflection efficiency of the regions A and B and the purpose of use.

  In the present invention, the area ratio of the region B is preferably 10 to 90% with respect to the effective pixel area (the area obtained by combining the area of the region A and the area of the region B). When this ratio is less than 10%, that is, when the ratio of the area having high transmission efficiency to the pixel is too high, the external light is too bright and the display is obscured. Will cause the same problem. On the other hand, if the area ratio of the region B exceeds 90%, even if the backlight is turned on and displayed when the ambient light becomes so dark that the display cannot be observed with only the ambient light, the region B is displayed. The ratio of A is too low and the display is difficult to see.

  In particular, when it is installed in a product form where the main usage environment is outdoors, it is necessary to place importance on the battery life, and it must be designed so that external light can be used efficiently, giving priority to low power consumption. . Therefore, the ratio of the region B having a high reflection efficiency is desirably 40 to 90%. Here, when 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 during which the backlight has to be turned on becomes long, so the battery life is shortened.

  On the other hand, when the main usage environment is installed in a product form indoors, it is designed to use the backlight light efficiently. Therefore, the ratio of the region B is desirably 10 to 60%. If the area ratio of the region B exceeds 60%, the area of the region A through which the backlight is transmitted is small, and the luminance of the backlight needs to be significantly higher than that of, for example, a transmissive liquid crystal display device. The power becomes high and the use efficiency of the backlight decreases.

  When the liquid crystal display device of the present invention is mounted on a battery-powered video camera, the brightness of the ambient light can always be kept easy to observe by adjusting the brightness of the backlight. did it. In particular, when used outdoors in fine weather, the backlight does not have to be turned on, so the power consumption is small and the battery usage time is greatly extended compared to those equipped with a transmissive liquid crystal display device. I was able to.

(Embodiment 2)
Hereinafter, Embodiment 2 will be described based on 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 the present embodiment, when a portion where the pixel electrode is formed is observed from above, a region A having a high transmission efficiency and a region B having a high reflection efficiency are divided at the vicinity of the center of the pixel. Yes.

  Note that the same reference numerals as those in the first embodiment are used for the reference numerals in the figure. The configuration and manufacturing process of the pixels and TFTs are the same as those in the first embodiment.

  3 and 4, ITO 7 having high transmission efficiency is provided from the vicinity of the center portion in the pixel to the vicinity of the self-stage gate line, and is partially connected to the drain electrode 5 of the TFT 4. Further, Al 8 having a high reflection efficiency is superimposed on the ITO 7 through the Mo 14 at the center of the pixel, extends in the direction of the next-stage gate wiring 2 opposite to the ITO 7, and has a gate insulating film 9 on the gate wiring 2. Are superimposed.

  Here, since ITO7 and Al8 are electrically connected via Mo14, the electrolytic corrosion by ITO7 and Al8 is suppressed. Further, Al 8, that is, the region B is superimposed on the next-stage gate wiring 2 through the gate insulating film 9, so that an auxiliary capacitance at the time of driving the liquid crystal is formed, and this region B also contributes to display. Therefore, the effective area of the pixel is significantly improved as compared with the conventional configuration.

  In order to further improve the aperture ratio, a film having high reflection efficiency such as Al8 is formed on the TFT 4 or the source wiring 3 via the insulating film as the pixel electrode 6 (electrically connected to the drain electrode 5). That's fine. However, in this case, 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 degradation 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 an active matrix substrate in the liquid crystal display device of the present embodiment, and FIG. 6 is a cross-sectional view taken along the line CC in FIG.

  The present embodiment is different from the second embodiment in that the common wiring 15 is disposed below the region B where the reflection efficiency is high via the gate insulating film 9.

  The reference numerals in the figure are the same as those in the first and second embodiments. Further, the configuration and manufacturing process of the pixel and TFT are the same as those in the first and second embodiments unless otherwise described.

  5 and 6, ITO 7 having high transmission efficiency is provided from the vicinity of the central portion in the pixel to the vicinity of the self-stage gate wiring 2, and is connected to the drain electrode 5 of the TFT 4. Further, Al 8 having a high reflection efficiency is superimposed on the ITO 7 via the Mo 14 in the center of the pixel, and extends to the vicinity of the next-stage gate wiring 2a on the opposite side of the ITO 7, and the common wiring 15 and the gate insulating film on the lower layer. 9 is superimposed.

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

  In order to further improve the aperture ratio, a film having a high reflection efficiency such as Al8 is formed on the TFT 4 or the source wiring 3 via an insulating film as the pixel electrode 6 (electrically connected to the drain electrode). Good. 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 parasitic capacitance does not occur between the pixel electrode 6 and the TFT 4 or the source wiring 3. For example, after the ITO 7 is formed, an organic insulating film having a dielectric constant of about 3.6 is deposited on the entire surface of the substrate to a thickness of about 3 μm, and then Al 8 is formed so as to overlap the pixel and the TFT 4 or the source wiring 3. Then, Al 8 may be electrically connected to the drain electrode 5. As a connection method, there is a method in which a contact hole is formed on the drain electrode 5 or the ITO 7 and connected through the contact hole.

  Further, in the present embodiment, the portion where the pixel electrode 6 is formed is divided into two regions, a region having a high transmission efficiency and a region having a high reflection efficiency. However, the present invention is not limited to this. Also good. 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 regions 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 are manufacturing methods of 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 the source wiring in the region B having a high reflection efficiency. In addition, the same code | symbol as the said Embodiment 1-3 was used about the reference code in the figure. Further, the configuration and manufacturing process of the pixel and TFT are the same as those in the first to third embodiments unless otherwise specified.

  When the active matrix substrate of the liquid crystal display device of this embodiment is observed from above, as shown in FIG. 8, a region A having high transmission efficiency is provided in the center of the pixel, and a band-like region B is provided so as to surround it. It has been. The outline of the region B is a quadrangle along the edges of the gate wiring and the source wiring. In the region B, a layer having a high reflection efficiency formed of the same material as the source wiring material is provided, so that the reflection efficiency is high.

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

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

  Next, as shown in FIG. 9D, ITO was formed as a layer 46 with high transmission efficiency over the entire area in each pixel. The layer 46 having high transmission efficiency may be any material other than ITO as long as the material has high transmission efficiency. The layer 46 with high transmission efficiency is electrically connected to the drain electrode 5 by being connected to the connection layer 43 through a contact hole 45 penetrating the interlayer insulating film 44. 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 the regions A and B by the layer 46 with high transmission efficiency. Yes. Therefore, compared to the case where the pixel electrode is formed by the layer having a high transmission efficiency in the region A and the layer having a high reflection efficiency in the region B, in this embodiment, the pixel electrode is formed only by the layer 46 having a high transmission efficiency. Therefore, as compared with the transmissive liquid crystal display device, there is an advantage that the number of processes is not increased, a region with high reflection efficiency can be formed, and pixel electrode formation defects are less likely to occur.

(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 are manufacturing methods of 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 the region B having a high reflection efficiency (shaded portion in FIG. 10). In addition, about the reference code in a figure, the code | symbol similar to the said Embodiment 1-4 was used. Further, the configuration and manufacturing process of the pixel and TFT are the same as those in the first to fourth embodiments unless otherwise described.

  In FIG. 10, when the active matrix substrate of the liquid crystal display device of this embodiment is observed from above, a region A having high transmission efficiency is provided in a square shape in the center of the pixel, and a band-shaped region B is provided so as to surround it. ing. The outline of the region B is a quadrangle along the edges of the gate wiring and the source wiring. In the region B, a layer having a high reflection efficiency formed of the same material as the gate wiring material is provided, so that the reflection efficiency is high.

  A method for manufacturing this liquid crystal display device will be described below. First, as shown in FIG. 11A, a conductive film is deposited on the insulating substrate 1. Subsequently, the conductive film is patterned to form the gate electrode 10, the gate wiring (shown in FIG. 10), and the layer 42 with high reflection efficiency. The portion where the layer 42 with high reflection efficiency is formed corresponds to the region B.

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 to be a source / drain electrode are sequentially formed. Further, the metal layer 3b that becomes a part of the source wiring 3 and the drain-pixel electrode connection layer 43 are formed by the same process. The connection layer 43 partially overlaps the drain electrode 5 of the TFT 4.

  Further, as shown in FIG. 11C, ITO is deposited by sputtering and patterned as a layer 46 having high transmission efficiency and an ITO layer 3a that becomes a part of the source wiring 3. The layer 46 with high transmission efficiency is formed over the entire area of 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 with 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 a high transmission efficiency is provided at the center in the pixel, and the strip-like region B having a 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 with high reflection efficiency which is a part of the pixel region exist in different layers, the regions A and B have a reverse pattern (the central portion). Compared to the case of a region having a high reflection efficiency), it is possible to narrow the interval for preventing leakage between the ITO layer 3a and the layer 42 having a high reflection efficiency. The aperture ratio can be improved.

  Further, in the present embodiment, as in the fourth embodiment, since the pixel electrode is formed with only one type of electrode (the layer 46 with high transmission efficiency), the pixel electrode is poorer than when the pixel electrode is formed with two types of electrodes. There is little generation and it can manufacture efficiently.

  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, it is electrically connected by the ITO layer 3a. Therefore, there is an advantage that disconnection of the source wiring 3 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 are manufacturing methods of the liquid crystal display device of the present embodiment. It corresponds to a cross section.

  In the present embodiment, an effective pixel area (an area that substantially functions as a pixel) can be improved by forming a pixel electrode on a gate wiring or a source wiring through an insulating film. In addition, about the reference code in a figure, the code | symbol similar to the said Embodiment 1-5 was used. Further, the configuration and manufacturing process of the pixel and TFT are the same as those in the first to fifth embodiments unless otherwise described.

  First, in FIG. 12, when the active matrix substrate of the liquid crystal display device of the present embodiment is observed from above, a region A having high transmission efficiency is provided in the central portion of the pixel, and a region B having high reflection efficiency in a band shape surrounding the region A. (The hatched portion in FIG. 12) is provided. The pixel electrode made of a layer having a high transmission efficiency is superimposed on the gate wiring and the source wiring through 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 enlarge the effective pixel area as compared with the form. 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. As shown in FIG. 13A, the gate electrode 10 and the gate wiring 2 (shown in FIG. 12), the gate insulating film 9, the semiconductor layer 12, the channel protective layer 13, and the source / drain electrodes are formed on the insulating substrate 1. An n ⁺ -Si layer 11 and a source wiring 3 are formed in this order. Note that it is preferable to use a material having high reflection efficiency for the gate wiring 2 or the source wiring 3 formed here to overlap with the light transmission layer to be a pixel electrode in at least a later step.

  Next, as shown in FIG. 13B, an interlayer insulating film 44 is formed, and then a contact hole 45 penetrating the interlayer insulating film 44 is formed. Subsequently, as shown in FIG. 13C, a high transmission efficiency layer 46 made of a material having high transmission efficiency such as ITO is formed by sputtering and patterned. The layer 46 with high transmission efficiency is connected to a connection layer 43 connected to the drain electrode 5 of the TFT 4 through a contact hole 45 penetrating the interlayer insulating film 44. Here, the layer 46 having a high transmission efficiency is patterned so as to overlap at least one of the gate wiring 2 and the source wiring 3, whereby the gate wiring 2 or the source wiring overlapping with the layer 46 having a high transmission efficiency through the interlayer insulating film 44. 3 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 and 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, a new reflection is performed. It is not necessary to install a highly efficient area, 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 an active matrix substrate in the liquid crystal display device according to the present embodiment. FIGS. 15A to 15C and FIGS. 16A to 16C illustrate the manufacture of the liquid crystal display device according to the present embodiment. It is sectional drawing which shows a method, and is equivalent to the GG cross section of FIG.

  As shown in FIG. 14, a region A with high transmission efficiency is provided at the center of the pixel, and a strip-like region B with high reflection efficiency (hatched portion in the figure) is provided along the edge of the source wiring 3. .

  In this region B, a convex part with a high height (shown in 53a in FIG. 16) and a convex part with a low height (shown in 53b in FIG. 16) randomly formed on the insulating substrate 1, and these There is a polymer resin (shown at 54 in FIG. 16) formed on the convex portion, and a layer with 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, which has a high reflection efficiency, has a continuous wave shape and is electrically connected to the drain electrode 5 via the contact hole 45 and the base electrode (not shown). ing.

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

  Then, a gate insulating film 9 made of SiNx, SiOx or the like is formed on the entire surface of the insulating substrate 1 so as to cover the gate wiring 2 and the gate electrode 10, and on the gate insulating film 9 above the gate electrode 10. For this, a semiconductor layer 12 made of amorphous silicon (a-Si), polycrystalline silicon, CdSe, or the like is formed. Then, contact layers 48 made of amorphous silicon (a-Si) or the like are formed on both ends of the semiconductor layer 12 so as to be separated from each other on the channel protective layer 13.

  A source 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, and a drain electrode 5 made of Ti, Mo, Al or the like is formed on the other side like the source electrode 49. Are superimposed. In the seventh embodiment, as the insulating substrate 1, for example, a glass plate having a thickness of 1.1 mm which is a product name 7059 manufactured by Corning Corporation can be used.

  Next, as shown in FIG. 15B, a base electrode 50 is formed at the same time as the metal layer 3b which becomes a part of the source wiring by forming and patterning a conductive film using a sputtering method. At this time, although not shown, the base electrode 50 is configured such that a part thereof overlaps the gate wiring 2 and the gate insulating film 9 in the next stage, thereby forming an auxiliary capacitance.

  At this time, the pixel region (region B) is formed by superimposing a layer having a high reflection efficiency on the region on the gate wiring forming the auxiliary capacitance or by increasing the reflection efficiency of the gate wiring itself. The aperture ratio can be further improved.

  Subsequently, as shown in FIG. 15C, the ITO layer 3a constituting the source wiring 3 together with the metal layer 3b was formed and patterned by sputtering. 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 there is a film defect in a part of the metal layer 3b that constitutes the source wiring 3, it is electrically connected by the ITO layer 3a, so that disconnection of the source wiring 3 can be reduced. There is an advantage.

  Furthermore, in this step, the ITO layer 3a was formed and the layer 46 with high transmission efficiency constituting the pixel electrode was patterned. By doing so, 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. 16 (a), a resist film 52 made of a photosensitive resin is formed and patterned, and subjected to heat treatment or the like to drop corners, whereby a part of the resist film 52 has a substantially circular cross section. The convex portion 53a having a high height and the convex portion 53b having a low height are formed in a portion corresponding to the region B. At this time, it is preferable not to form the convex portions 53a and 53b on the high transmission efficiency layer 46 in order to efficiently apply a voltage to the liquid crystal layer, but even if formed, if it is transparent, There is no significant effect optically.

  Next, as shown in FIG. 16B, a polymer film 54 is formed along the convex portions 53a and 53b. By this step, the uneven surface in the region B can be formed into a smoother shape with few flat portions. However, this process can be omitted by changing the manufacturing conditions.

  Subsequently, as shown in FIG. 16C, a layer 42 having a high reflection efficiency made of Al as a pixel electrode was formed at a predetermined position on the above-described polymer film 54 by, for example, a sputtering method. As a material suitable for use as the layer 42 with high reflection efficiency, in addition to Al and Al alloy, for example, Ta, Ni, Cr, Ag, etc. with high reflection efficiency can be cited. A thickness of about 0.01 to 1.0 μm is suitable.

  As described above, according to the present embodiment, the region A having a high transmission efficiency is formed in the central portion of the pixel, and the region B having a 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 having a high reflection efficiency which is a part of the pixel region exist in different layers, a reverse pattern (the central portion is a region having a high reflection efficiency). Compared with the case (case), the interval provided for preventing leakage of these 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 concavo-convex structure in order to scatter the reflected light over a wide range. However, when the scatter sheet is used together, the resist film 52 does not form the concavo-convex. The surface of the layer 42 with high reflection efficiency may be flat. In any case, the layer 42 having high reflection efficiency and the layer 46 having high transmission efficiency constituting the pixel electrode exist as separate layers with a third substance (for example, resin, metal such as Mo) interposed therebetween. As a result, when ITO or Al or its alloy is used as the material of the layer having a high transmission efficiency, particularly, as the material of the layer B having a high reflection efficiency corresponding to the pattern of the region B, the electric power that is likely to be generated in the etching process of Al. It is possible to reduce Al patterning defects caused by the food reaction.

(Embodiment 8)
Hereinafter, the 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 the HH cross section of FIG.

  In FIG. 17 and FIG. 18, pixel electrodes 6 are provided in a matrix on the active matrix substrate, and gate wirings 2 for supplying scanning signals so as to pass through the periphery of the pixel electrodes 6 and are orthogonal to each other. Source wiring 3 for supplying a display signal is provided. The gate wiring 2 and the source wiring 3 partially overlap the outer peripheral portion of the pixel electrode 6 with the 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 in the vicinity of the intersection of the gate line 2 and the source line 3. A gate wiring 2 is connected to the gate electrode 10 of the TFT 4, and the TFT 4 is driven and controlled by a signal input to the gate electrode 10. 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 through the contact hole 45.

  The connection electrode 55 forms an auxiliary capacitance with the common wiring 15 through 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 process as the gate wiring 2, the process can be shortened.

  The pixel electrode 6 is formed of a layer 42 with high reflection efficiency made of Al or an Al-based alloy and a layer 46 with high transmission efficiency made of ITO. When the pixel electrode 6 is observed from the upper surface, it consists of a region A having a high transmission efficiency and a region B having a high reflection efficiency (corresponding to the hatched portion in FIG. 17). However, the layer 42 having a high reflection efficiency may be a metal layer having a high reflection efficiency such as Ta as in the case of the other embodiments.

  Here, the region B is designed so as to cover a part of the light-shielding electrode and the wiring part which do not transmit the backlight light, such as the gate wiring 2, the source wiring 3, the TFT 4 and the common wiring 15. With this structure, an area that cannot be used as the area A can be used as the area B with 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 Embodiment 8 is configured and can be manufactured as follows.

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

  The source wiring 3 has a two-layer structure of an ITO layer 3a and a metal layer 3b, and even if a part of the metal layer 3b has a defect such as disconnection, the source wiring 3 is electrically connected by the ITO layer 3a. Disconnection can be reduced.

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

  In this way, by using a photosensitive acrylic resin as the interlayer insulating film 44, a thin film can be formed by a spin coating method, so that a thin film with a thickness of several μm can be easily formed. The patterning 44 is advantageous in terms of productivity, such as eliminating the need for a photoresist coating process.

  The acrylic resin used in this embodiment is colored and can be made transparent by performing an exposure process on the entire surface after patterning. Needless to say, the transparency treatment can be performed chemically and may be used.

  Thereafter, ITO, which becomes the layer 46 with high transmission efficiency of the pixel electrode 6, is formed by sputtering and patterned. As a result, the layer 46 having high transmission efficiency, which is the pixel electrode 6, is electrically connected to the connection electrode 55 through the contact hole 45 that penetrates the interlayer insulating film 44.

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

  In this way, the active matrix substrate of this embodiment can be manufactured. Further, as shown in FIG. 18, the active matrix substrate and the counter substrate 56 are bonded together, and liquid crystal is sealed in these gaps, thereby completing the 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 TFT 4, the gate wiring 2, and the source electrode 3 in the portion corresponding to the region B of the pixel electrode 6. It is not necessary to provide a light-shielding film for shielding the pixel electrodes on the gate wiring, source wiring, and common wiring that prevent the incidence of light and prevent light leakage in the display area such as domains and disclination lines. In addition, since a region that could not be used as a display region because a light-shielding film is conventionally provided to shield the light can be used as the display region of the pixel electrode, the display region of the liquid crystal panel can be used effectively. .

  In addition, when the gate wiring and the source wiring are formed of a metal film, these wirings conventionally cannot be used as a display region because the backlight is blocked by the transmissive display device. In the embodiment, a region A with high transmission efficiency is provided at the center of the pixel (two in this embodiment), and a band-like region B with high reflection efficiency is provided so as to surround it. Therefore, a region B having high reflection efficiency can be formed above the gate wiring, source wiring, common wiring, and switching element, and this can be used as the reflection region of the pixel electrode. The aperture ratio of the pixel electrode can be improved more than when the pattern surrounds the region B).

  In addition, as shown in FIG. 19, the connection electrode 55 is provided in the area B indicated by oblique lines, so that a decrease in the luminance of transmitted light in the area A can be suppressed.

(Embodiment 9)
Hereinafter, Embodiment 9 will be described with reference to the drawings. FIG. 20 is a partial plan view of the substrate in the simple matrix type liquid crystal display device of this embodiment, and FIGS. 20B and 20C are cross-sectional views taken along the line CC in FIG.

  In FIG. 20, a plurality of stripe-shaped electrodes 20 are arranged so as to be orthogonal to each other on a pair of transparent insulating substrates made of glass, plastic, or the like. The portion where the pixel 6 is formed is composed of 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 this embodiment, the pixel 6 is transmitted to the central portion of the pixel. ITO 7 (Indium Tin Oxide) is provided as a high-efficiency layer, and a layer 8 having a two-layer structure of Al and Mo is provided as a layer with high reflection efficiency covering the periphery of the ITO 7 (Indium Tin Oxide). Pixel 6 is formed.

  Then, although not shown, an alignment film is applied on the substrate as described above, the pair of substrates are bonded so that the stripe-shaped electrodes 20 are orthogonally crossed, and liquid crystal is sealed between these substrates, The liquid crystal display device of this embodiment is completed by installing the backlight. When color display is desired, this can be realized by disposing a color filter composed of colored layers such as red, green, and blue in front of the liquid crystal layer.

  Hereinafter, a method for manufacturing the simple matrix type liquid crystal display device of this embodiment will be briefly described with reference to FIGS. As shown in FIG. 20, an ITO layer 3a (lower layer) and a metal layer 3b (upper layer) are sequentially formed on the insulating substrate 1 as a striped electrode 20 by sputtering, and then patterned. In the present embodiment, ITO 7 and Al8 are used as the electrode 20 to form a region A having a high transmission efficiency and a region B having a high reflection efficiency.

  In addition, when the thickness of Al is 100 nm or more, a sufficiently stable reflection efficiency (about 90%) can be obtained. However, in this embodiment, the thickness of Al is 100 nm and the thickness of Mo is 50 nm. 90%, and ambient light can be effectively reflected. In addition, as a material having 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 stripe-shaped electrode 20 is provided with the region B having a high reflection efficiency and the region A having a high transmission efficiency, so that it is compared with a liquid crystal display device using a conventional transflective film. Thus, a liquid crystal display device capable of transmissive display, reflective display, or a dual display while using ambient light and illumination light without loss is realized.

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

  Further, when a liquid crystal display device is manufactured by using the substrate shown in FIG. 20C with the counter substrate 23 on which the counter electrode 22 is formed, as shown in FIG. 21, it corresponds to the region A having high transmission efficiency. The cell thickness dt of the liquid crystal layer 24 and the cell thickness dr of the liquid crystal layer 24 corresponding to the region B having high reflection efficiency differ by the amount of the insulating layer. By utilizing this, the optical characteristics of both modes can be matched. For example, when a liquid crystal display device is produced so that dt> dr, the optical path lengths of both modes can be made close to each other, so that a good display can be obtained. Further, when the liquid crystal display device is manufactured while adjusting the film thickness of the insulating layer and the spacers indicating both substrates so that dt = 2dr, if the voltage supply state is the same, both electro-optics Since the consistency of characteristics is further improved and the brightness and contrast are aligned in both modes, a better display can be obtained.

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

  In this liquid crystal display device, the ratio of the region A having high transmission efficiency to the region B having high reflection efficiency is set to about 4 to 6 with respect to the pixels, the region A having high transmission efficiency is ITO, and the region having high reflection efficiency is used. B was formed of Al. Further, the cell thickness of the region A having high transmission efficiency is set to about 5.5 μm, whereas the cell thickness of the region B having high reflection efficiency is set to about 3 μm. This is because 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 are matched as much as possible. As shown in FIG. 22, the region A having a high transmission efficiency has almost the same transmittance / reflectance in 64-gradation display of the transmitted light from the backlight and the reflected light from the external light. A sufficient display quality can also be obtained when displaying both the transmitted light by the light and the reflected light by the external light at the same time. The contrast ratio at this time was about 200 for the transmitted light from the backlight and about 25 for the reflected light from the outside light.

  FIG. 23 shows the color reproducibility of a conventional 8.4 inch diagonal transmission type liquid crystal display device, and FIG. 24 shows the region 8.4 inch diagonal high transmission efficiency A and the reflection efficiency in this embodiment. The color reproducibility of the liquid crystal display device provided with the high region B is shown. As shown in FIG. 23, in the conventional liquid crystal display device, the color reproduction range is remarkably lowered as the panel illuminance of external light increases to 800 (lx) and 1700 (lx). However, as shown in FIG. 24, in the liquid crystal display device according to the present embodiment, even when the panel illuminance of external light increases to 800 (lx) and 1700 (lx), the color reproduction range hardly deteriorates. This is because the contrast of the conventional liquid crystal display device is reduced due to surface reflection of external light on the surface of the liquid crystal display device and reflected light from a black mask / bus line for light shielding. On the other hand, since the liquid crystal display device according to the present embodiment performs display in the reflection region using external light, how much the external light is reduced in contrast reduction that has occurred in the conventional liquid crystal display device. However, the contrast does not decrease in the reflection region. Therefore, in the liquid crystal display device provided with the region A with high transmission efficiency and the region B with high reflection efficiency in this embodiment, the color reproduction range hardly deteriorates no matter how much the panel illuminance of external light increases. It is possible to perform display with high visibility under any environment.

  As in this embodiment, a liquid crystal display device provided with a region with high transmission efficiency and a region with high reflection efficiency is said to change the orientation of the screen for the convenience of the user or move to an easy-to-view environment. It is particularly effective if it is installed in a product that cannot be used.

  In addition, regarding the characteristic points of the liquid crystal display device in this embodiment, even when the liquid crystal display device is manufactured using the substrate shown in FIG. can get.

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

  In the present invention, the area ratio of the region B is preferably 10 to 90% with respect to the effective pixel area (the area obtained by combining the area of the region A and the area of the region B). When this ratio is less than 10%, that is, when the ratio of the area having high transmission efficiency to the pixel is too high, the external light is too bright and the display is obscured. Will cause the same problem. On the other hand, if the area ratio of the region B exceeds 90%, even if the backlight is turned on and displayed when the ambient light becomes so dark that the display cannot be observed with only the ambient light, the region B is displayed. The ratio of A is too low and the display is difficult to see.

  In particular, when it is installed in a product form where the main usage environment is outdoors, it is necessary to place importance on the battery life, and it must be designed so that external light can be used efficiently, giving priority to low power consumption. . Therefore, the ratio of the region B having a high reflection efficiency is desirably 40 to 90%. Here, when 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 during which the backlight has to be turned on becomes long, so the battery life is shortened.

  On the other hand, when the main usage environment is installed in a product form indoors, it is designed to use the backlight light efficiently. Therefore, the ratio of the region B is desirably 10 to 60%. If the area ratio of the region B exceeds 60%, the area of the region A through which the backlight is transmitted is small, and the luminance of the backlight needs to be significantly higher than that of, for example, a transmissive liquid crystal display device. The power becomes high and the use efficiency of the backlight decreases.

  In the above-described embodiment, when the substrate is observed from above, a region A having high transmission efficiency is provided in the center of the pixel, and a region B having high reflection efficiency is provided so as to surround it. Although the configuration has been described, the present invention is not limited to this. For example, as shown in FIGS. 25A to 25C, a region B having a high reflection efficiency is provided in the center of the pixel, It may be configured such that a region A having a high transmission efficiency is provided. Such a simple matrix type liquid crystal display device can also be manufactured by a method similar to that of 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 FIGS. 26B and 26C are cross-sectional views taken along the line CC in FIG. is there.

  In this embodiment, when a portion where the striped electrode 20 is formed is observed from above, a region A having a high transmission efficiency and a region B having a high reflection efficiency are divided with the vicinity of the pixel center as a boundary. It has become. The reference numerals in the figure are the same as those in the ninth embodiment. Further, the configuration of the pixel and the manufacturing process are the same as those in the ninth embodiment unless otherwise described.

  As shown in FIG. 26, in this embodiment, ITO 7 having high transmission efficiency is provided by being divided from the vicinity of the central portion in the pixel, and a layer 8 having a two-layer structure of Al and Mo is provided in the central portion of the pixel. It overlaps with the ITO 7 and is divided and provided on the opposite side to the ITO 7.

  As described above, in this embodiment, the stripe-shaped electrode 20 is provided with the region B having a high transmission efficiency and the region A having a high transmission efficiency, so that it is compared with a liquid crystal display device using a conventional transflective film. A liquid crystal display device capable of transmissive display, reflective display, or a dual display while using ambient light and illumination light without loss is realized.

  In FIG. 26B, the electrode 20 is divided from the vicinity of the central portion in the pixel 6 so that Al is superimposed on the ITO, and the ITO is formed on the entire surface of the pixel 6. In FIG. 26C, ITO and Al are divided and formed partially overlapping in the vicinity of the central portion in the pixel 6.

  In the above-described embodiment, when the portion where the striped electrode 20 is formed is observed from above, the region A having high transmission efficiency and the region B having high reflection efficiency are divided with the vicinity of the pixel center as a boundary. However, the present invention is not limited to this. For example, as shown in FIGS. 27 (a) and 27 (b), the reflective electrode 20 has a high reflection efficiency at the center in the stripe-shaped electrode 20. The region B may be provided, and the region A having high transmission efficiency may be provided on both sides so as to cover the region B. Such a simple matrix type liquid crystal display device can also be manufactured by a method similar to that of the above-described embodiment.

  Although the first to eighth embodiments of the liquid crystal display device of the present invention have been described above, differences between the present invention and the conventional reflective liquid crystal display device or transmissive liquid crystal display device will be further described below.

  Conventional reflective liquid crystal display devices use ambient light for low power consumption, and display is recognized when ambient light is darker than a certain threshold value even in an environment where sufficient power can be supplied. Can not do. This is the biggest drawback of the reflective liquid crystal display device.

  In addition, if the reflection characteristics of the reflective electrode vary in the manufacture, the utilization efficiency of the ambient light also varies, and the ambient light intensity as a critical value at which the display cannot be recognized varies from panel to panel. For this reason, a liquid crystal display device having stable display characteristics cannot be obtained unless the reflection characteristic variation is controlled more than the variation in aperture ratio in the conventional transmissive liquid crystal display device.

  In contrast, the liquid crystal display device of the present invention uses backlight light in an environment where sufficient power can be supplied, as in the case of a conventional transmissive liquid crystal display device, so that display recognition is possible regardless of the intensity of ambient light. Become. Therefore, the present invention has an advantage that the variation in the utilization efficiency of the ambient light due to the variation in the reflection characteristics does not need to be controlled as finely as the reflection type liquid crystal display device.

  On the other hand, in a conventional transmissive liquid crystal display device, when ambient light becomes brighter, the surface reflection component increases, and thus display recognition tends to be 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 brightness is increased by using the reflection region together with the brighter ambient light.

  As described above, the liquid crystal display device according to the present invention has the problem that the visibility is lowered due to surface reflection in a conventional transmissive liquid crystal display device in a bright ambient environment, and the ambient light in the conventional reflective liquid crystal display device. Both of the problems that display observation becomes difficult due to a decrease in panel luminance in a dark environment can be solved at the same time, and the present invention has excellent features.

It is a top view which shows the liquid crystal display device of Embodiment 1 of this invention. It is AA sectional drawing of FIG. It is a top view which shows the liquid crystal display device of Embodiment 2 of this invention. It is BB sectional drawing of FIG. It is a top view which shows the liquid crystal display device of Embodiment 3 of this invention. It is CC sectional drawing of FIG. It is a top view which shows the liquid crystal display device of other embodiment of this invention. It is a top view which shows the liquid crystal display device of Embodiment 4 of this invention. It is DD sectional drawing of FIG. It is a top view which shows the liquid crystal display device of Embodiment 5 of this invention. It is EE sectional drawing of FIG. It is a top view which shows the liquid crystal display device of Embodiment 6 of this invention. It is FF sectional drawing of FIG. It is a top view which shows the liquid crystal display device of Embodiment 7 of this invention. It is a figure which shows the manufacture right method of the liquid crystal display device equivalent to the GG cross section of FIG. It is a figure which shows the manufacture right method of the liquid crystal display device equivalent to the GG cross section of FIG. It is a top view which shows the liquid crystal display device of Embodiment 8 of this invention. It is HH sectional drawing of FIG. FIG. 10 is a plan view showing another liquid crystal display device according to Embodiment 8. It is a figure which shows the simple matrix type liquid crystal display device in Embodiment 9. FIG. 10 is a cross-sectional view illustrating a simple matrix liquid crystal display device according to Embodiment 9. It is a surface which shows the characteristic evaluation of the liquid crystal display device in Embodiment 9. It is a surface which shows the color reproducibility of the conventional transmissive liquid crystal display device used in Embodiment 9. It is a surface which shows the color reproducibility of the liquid crystal display device in Embodiment 9. It is drawing which shows the other simple matrix type liquid crystal display device in Embodiment 9. FIG. It is drawing which shows the simple matrix type liquid crystal display device in Embodiment 10. FIG. It is drawing which shows the other simple matrix type liquid crystal display device in Embodiment 10. FIG. It is a top view which shows the conventional liquid crystal display device.

Explanation 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 protective layer 14 Mo
DESCRIPTION OF SYMBOLS 15 Common wiring 20 Striped electrode 21 Insulating layer 22 Stripe counter electrode 23 Counter substrate 24 Liquid crystal layer 30 Polarizing plate 31 Phase difference plate 32 Transparent substrate 33 Black mask 34 Counter electrode 35 Orientation film 36 Liquid crystal layer 37 MIM
39 Light Source 41 Conductive Film 42 High Reflective Efficiency Layer 43 (Drain-Pixel Electrode) Connection Layer 44 Interlayer Insulating Film 45 Contact Hole 46 High Transmission Efficiency Layer 47 Passivation Film 48 Contact Layer 49 Source Electrode 50 Base Electrode 52 Resist Film 53a High High convex part 53b Low convex part 54 Passivation film 55 Connection electrode 56 Counter substrate

Claims (3)

In a liquid crystal display device including a plurality of pixels defined by a pair of electrodes in which a liquid crystal layer is held between at least two substrates and a voltage is applied to the liquid crystal layer.
In the plurality of pixels, a region having a high light transmission efficiency and a region having a high reflection efficiency are provided, and a layer having a high light transmission efficiency or a layer having a high reflection efficiency is used as a pixel electrode in each of the regions. A liquid crystal display device that functions, wherein the layer having high transmission efficiency is ITO, and the layer having high reflection efficiency is Al or an Al-based alloy.   2. The liquid crystal display device according to claim 1, wherein the thickness of the layer having high reflection efficiency is 0.01 to 1.0 [mu] m. 3. The liquid crystal display device according to claim 2, wherein the thickness of the layer having high reflection efficiency is 100 nm or more.

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