JP3799031B2 - Liquid crystal display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device, and more particularly, to a transflective liquid crystal display in which the same saturation is applied to a transmissive region and a reflective region by applying different common voltages to the transmissive region and the reflective region. Relates to the device.
[0002]
[Prior art]
A color liquid crystal display panel is composed of two transparent substrates and a liquid crystal layer between the transparent substrates. In general, a TN (Twisted Nematic) type liquid crystal often used in an existing TFT liquid crystal display is a nematic liquid crystal. This kind of liquid crystal molecules are arranged one-dimensionally and regularly in space. All nematic liquid crystal molecules are aligned so that the major axis of each molecule is in a predetermined direction and the molecules are parallel to each other. Nematic liquid crystals have a low viscosity and are easy to flow (this fluidity is mainly due to the fact that liquid crystal molecules can move more freely in the major axis direction).
[0003]
Since the liquid crystal molecules have an anisotropic configuration, the photoelectric effect differs depending on the direction. That is, there is anisotropy when viewed from the photoelectric characteristics (for example, dielectric coefficient and refractive index) of the liquid crystal molecules. Since the saturation in the display element is formed by changing the intensity of incident light using such characteristics, application as a display element becomes possible.
[0004]
For example, the dielectric coefficient ε (dielectric permittivity) is divided into two quantities in two directions, that is, ε‖ (a quantity parallel to the liquid crystal major axis direction) and ε⊥ (a quantity perpendicular to the liquid crystal direction). When ε‖> ε⊥, the liquid crystal is called a liquid crystal having a positive dielectric anisotropy (hereinafter simply referred to as a positive liquid crystal), and is used in the case of parallel matching. On the other hand, when ε‖ <ε⊥, the liquid crystal is called a liquid crystal having a negative dielectric anisotropy and is used only in the case of vertical matching. When a voltage is applied, whether the dielectric anisotropy of liquid crystal molecules is positive or negative means that the rotation direction of the liquid crystal molecules is parallel or perpendicular to the voltage, that is, light is transmitted or not transmitted. It depends on how.
[0005]
At present, the TN type liquid crystal often used in TFT-LCD is a liquid crystal with a positive dielectric constant.
[0006]
FIG. 1A is a diagram showing a liquid crystal alignment pattern when no voltage is applied to the plus type liquid crystal, and FIG. 1B is a diagram showing a liquid crystal arrangement pattern when the voltage V1 is applied to the plus type liquid crystal.
[0007]
Referring to FIG. 1A, when no voltage is applied to the pixel electrode 12 and the common electrode 13 (or when the same voltage is applied to both electrodes and the voltage difference in the liquid crystal layer 11 is zero). That is, when no voltage is applied to the liquid crystal layer 11, the liquid crystals 14 are arranged in parallel along the horizontal direction. At this time, the light beam can be transmitted from the transmission region and the reflection region and emitted from the liquid crystal display.
[0008]
On the other hand, when a voltage is applied to the liquid crystal layer 11, the liquid crystal 14 cannot be aligned in parallel along the horizontal direction and starts to rotate in the vertical direction. When the applied voltage reaches a predetermined value V1, the liquid crystal 14 is perpendicular to the pixel electrode 12 and the common electrode 13, as shown in FIG. 1B. At this time, the light beam cannot be transmitted from the transmission region and the reflection region, and cannot be emitted from the liquid crystal display.
[0009]
FIG. 2A is a diagram showing a TV curve (showing the relationship between transmittance and applied voltage) and an RV curve (showing the relationship between reflectance and applied voltage).
[0010]
As shown in FIG. 2A, the greater the applied voltage, the smaller the transmittance or reflectance. Therefore, saturation can be formed by changing the intensity of incident light using such characteristics.
[0011]
FIG. 2B is a cross-sectional view showing a conventional transflective liquid crystal display device.
[0012]
In FIG. 2B, the pixel electrode is composed of a transmissive electrode 21 and a reflective electrode 22 that are electrically connected to each other, but the common electrode 23 is composed of a one-piece transparent conductor layer, and there is no division between the transmissive region and the reflective region. Accordingly, when a voltage is applied to the pixel electrode and the common electrode, the applied voltages in the transmissive region and the reflective region are the same.
[0013]
However, the TV curve and the RV curve are not the same (that is, they do not overlap, see FIG. 2A). For this reason, at the same applied voltage, the light transmittance and reflectance are different, and the saturation in the reflection region and the saturation in the transmission region are different. Therefore, in the liquid crystal display, the color of the reflection region and the color of the transmission region are different. Therefore, the saturation due to the transmission method and the saturation due to the reflection method are different (the transmission method is a method for performing display in the transmission region using the light source of the liquid crystal display itself, and the reflection method is a light source outside the liquid crystal display). Therefore, it refers to a method of performing display in the reflection area). For example, when the transmission method is used, the display device exhibits a blue color, whereas when the reflection method is used, the display device exhibits a light blue color. This creates a problem where the user has questions about the quality of the product.
[0014]
[Problems to be solved by the invention]
As described above, in the conventional transflective liquid crystal display, the common electrode is formed of a one-piece transparent conductor layer, and there is no division between the transmissive region and the reflective region. For this reason, when a voltage is applied to the pixel electrode and the common electrode, the applied voltages in the transmissive region and the reflective region are the same. However, since the TV curve and the RV curve are not the same, the saturation by the transmission method and the saturation by the reflection method are different in the display of the liquid crystal display.
[0015]
In order to solve the above problems, the object of the present invention is to match the saturation of the transmissive area and the saturation of the reflective area in a liquid crystal display by applying different common voltages to the transmissive area and the reflective area. An object of the present invention is to provide a liquid crystal display device that can be made to operate.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, a liquid crystal display device of the present invention includes a first substrate having a plurality of transmission regions and a plurality of reflection regions, a transmission electrode positioned in the transmission region, and the transmission electrode positioned in the reflection region. A reflective electrode electrically connected to the plurality of first common electrodes provided at positions corresponding to the transmissive region, and provided at positions corresponding to the reflective region and electrically insulated from the first common electrode. a second substrate having a plurality of second common electrode which is the first Ri Do and a liquid crystal layer disposed between the substrate and the second substrate, the distance of the first substrate and the second common electrode, Different from the distance between the second common electrode and the second substrate.
In the liquid crystal display device, it is preferable that the first common electrode extends to an upper side corresponding to the reflection region.
[0018]
In the liquid crystal display device, it is preferable that the second common electrode extends to an upper side corresponding to the transmission region.
[0019]
In the liquid crystal display device, the first substrate and the second substrate may be transparent substrates.
[0020]
In the liquid crystal display device, the transmissive electrode may be a transparent conductor. The transparent conductor may be made of indium tin oxide (ITO) or indium zinc oxide (IZO).
[0021]
In the liquid crystal display device, the reflective electrode may be composed of a metal layer. Note that the material of the metal layer may be any of Al, Ag, and AlNd alloy.
[0022]
In the liquid crystal display device, the first common electrode and the second common electrode may be formed of a transparent conductor layer. The material of the transparent conductor layer may be indium tin oxide (ITO) or indium zinc oxide (IZO).
[0024]
In the liquid crystal display device, a distance between the first common electrode and the second substrate may be shorter than a distance between the second common electrode and the second substrate.
[0025]
In the liquid crystal display device, a distance between the first common electrode and the second substrate may be longer than a distance between the second common electrode and the second substrate.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
The configuration and operation of an embodiment of the present invention that accomplishes the above-described object and eliminates the drawbacks of the prior art will be described in detail with reference to the accompanying drawings.
[0027]
FIG. 3 is a sectional view showing a transflective liquid crystal display according to the first embodiment of the present invention.
[0028]
In FIG. 3, in the transflective liquid crystal display, one of the pixels has two parts, that is, a transmissive region II and a reflective region I. The formation of the liquid crystal display is as follows.
[0029]
First, a thin film transistor 31 and a transparent insulating layer 321 are sequentially formed inside one transparent substrate 301. Here, the transparent insulating layer 321 may be, for example, a silicon oxide (SiOx) layer, a silicon nitride (SiNx) layer, or a laminate thereof.
[0030]
Next, the transmissive region II and the reflective region I are defined. A pad insulating layer 322 having a bump on the surface is formed at the position of the reflective region I. As the material of the pad insulating layer 322, a photosensitive resin, an insulating material that transmits light, or an insulating material that does not transmit light may be used.
[0031]
For example, the material of the pad insulating layer 322 is a photosensitive resin. In this case, the photosensitive resin is applied to the transparent substrate, and the reflection area is patterned by exposure / development.
[0032]
After the patterning of the transmissive region and the reflective region is completed, the transmissive electrode 34 and the reflective electrode 33 are formed. Here, the transmissive electrode 34 in the transmissive region II may be formed by depositing indium tin oxide (ITO) or indium zinc oxide (IZO) by a sputtering method. The reflective electrode 33 in the reflective region I can be formed by depositing aluminum (Al), silver (Ag), or an aluminum neodymium (AlBd) alloy by sputtering.
[0033]
Next, the pixel electrode is formed by electrically connecting the transmissive electrode 34 and the reflective electrode 33. The pixel electrode is electrically connected to the thin film transistor 31.
[0034]
On the other hand, after the color filter 35 is formed inside the other transparent substrate 30 2, the reflective region common electrode 36 and the transmissive region common electrode 37 are formed.
[0035]
The method for forming both electrodes includes a step of forming a film of indium tin oxide (ITO) or indium zinc oxide (IZO) by a sputtering method, and a step of separating (electrically blocking) both electrodes by photolithography and etching. Composed.
[0036]
Since both electrodes are electrically cut off, when operating the liquid crystal display, different voltages are applied to the reflective region common electrode 36 and the transmissive region common electrode 37, respectively, so that the applied voltage in the reflective region and the transmissive region are The applied voltage can be adjusted so that the applied voltage is different. Therefore, since the TV curve and the RV curve do not overlap, the conventional problem that the saturation of the reflection area and the transmission area to which the same voltage is applied is different is solved.
[0037]
Finally, the transparent substrates 301 and 302 are aligned so that the inner surfaces of the transparent substrates 301 and 302 face each other, and liquid crystal is injected to form the liquid crystal layer 39. Here, the liquid crystal display is completed.
[0038]
FIG. 4 is a sectional view showing a transflective liquid crystal display according to a second embodiment of the present invention.
[0039]
In FIG. 4, in the transflective liquid crystal display, one of the pixels has two parts, that is, a transmissive region II and a reflective region I. The formation of the liquid crystal display is as follows.
[0040]
First, the thin film transistor 41 and the transparent insulating layer 421 are sequentially formed inside one transparent substrate 401. Here, the transparent insulating layer 421 may be, for example, a silicon oxide (SiOx) layer, a silicon nitride (SiNx) layer, or a laminate thereof.
[0041]
Next, the transmissive region II and the reflective region I are defined. A pad insulating layer 422 having a protrusion on the surface is formed at the position of the reflective region I. As the material of the pad insulating layer 422, a photosensitive resin, an insulating material that transmits light, or an insulating material that does not transmit light may be used.
[0042]
For example, the material of the pad insulating layer 422 is a photosensitive resin. In this case, the photosensitive resin is applied to the transparent substrate, and the reflection area is patterned by exposure / development.
[0043]
After the patterning of the transmissive region and the reflective region is completed, the transmissive electrode 44 and the reflective electrode 43 are formed. Here, the transmissive electrode 44 in the transmissive region II may be formed by depositing ITO or IZO by sputtering. The reflective electrode 43 in the reflective region I can be formed by forming aluminum (Al), silver (Ag), or an aluminum neodymium (AlBd) alloy by sputtering.
[0044]
Next, a pixel electrode is formed by electrically connecting the transmissive electrode 44 and the reflective electrode 43. The pixel electrode is electrically connected to the thin film transistor 41.
[0045]
On the other hand, after the color filter 45 is formed inside the other transparent substrate 402, the reflective region common electrode 46 and the transmissive region common electrode 47 are formed.
[0046]
The method of forming the electrodes includes a step of depositing a transparent insulating layer 48, a step of removing the transparent insulating layer corresponding to the transmission region II by photolithography and etching, a step of forming ITO or IZO by sputtering, It consists of a step of separating (electrically blocking) both electrodes by lithography and etching.
[0047]
Since both electrodes are electrically cut off, when operating the liquid crystal display, by applying different voltages to the reflective region common electrode 46 and the transmissive region common electrode 47, the applied voltage in the reflective region and the transmissive region are applied. The applied voltage can be adjusted so that the applied voltage is different. For this reason, since the TV curve and the RV curve do not overlap, the conventional problem that the saturation of the reflection region and the transmission region to which the same voltage is applied is different is solved.
[0048]
Finally, the transparent substrates 401 and 402 are aligned so that the inner surfaces of the transparent substrates 401 and 402 face each other, and liquid crystal is injected to form a liquid crystal layer 49. Here, the liquid crystal display is completed.
[0049]
FIG. 5 is a sectional view showing a transflective liquid crystal display according to a third embodiment of the present invention.
[0050]
In FIG. 5, in the transflective liquid crystal display, one of the pixels has two parts, that is, a transmissive region II and a reflective region I. The formation of the liquid crystal display is as follows.
[0051]
First, a thin film transistor 51 and a transparent insulating layer 521 are sequentially formed inside one transparent substrate 501. Here, the transparent insulating layer 521 may be, for example, a silicon oxide (SiOx) layer, a silicon nitride (SiNx) layer, or a laminate thereof.
[0052]
Next, the transmissive region II and the reflective region I are defined. A pad insulating layer 522 having a protrusion on the surface is formed at the position of the reflective region I. As the material of the pad insulating layer 522, a photosensitive resin, an insulating material that transmits light, or an insulating material that does not transmit light may be used.
[0053]
For example, the material of the pad insulating layer 522 is a photosensitive resin. In this case, the photosensitive resin is applied to the transparent substrate, and the reflection area is patterned by exposure / development.
[0054]
After the patterning of the transmissive region and the reflective region is completed, the transmissive electrode 54 and the reflective electrode 53 are formed. Here, the transmissive electrode 54 in the transmissive region II may be formed by depositing ITO or IZO by sputtering. The reflective electrode 53 in the reflective region I can be formed by forming aluminum (Al), silver (Ag), or an aluminum neodymium (AlBd) alloy by sputtering.
[0055]
Next, the pixel electrode is formed by electrically connecting the transmissive electrode 54 and the reflective electrode 53. The pixel electrode is electrically connected to the thin film transistor 51.
[0056]
On the other hand, after the color filter 55 is formed inside the other transparent substrate 502, the reflective region common electrode 56 and the transmissive region common electrode 57 are formed.
[0057]
The two electrodes are formed by sputtering, forming a film of indium tin oxide (ITO) or indium zinc oxide (IZO), depositing a transparent insulating layer 58, and transmitting regions by photolithography and etching. It consists of a step of removing the transparent insulating layer corresponding to II, a step of depositing ITO or IZO by sputtering, and a step of separating (electrically shutting off) both electrodes by photolithography and etching.
[0058]
Since both electrodes are electrically cut off, when operating the liquid crystal display, by applying different voltages to the reflective region common electrode 56 and the transmissive region common electrode 57, the applied voltage in the reflective region and the transmissive region are applied. The applied voltage can be adjusted so that the applied voltage is different. For this reason, since the TV curve and the RV curve do not overlap, the conventional problem that the saturation of the reflection region and the transmission region to which the same voltage is applied is different is solved.
[0059]
Finally, the transparent substrates 501 and 502 are aligned so that the inner surfaces of the transparent substrates 501 and 502 face each other, and liquid crystal is injected to form a liquid crystal layer 59. Here, the liquid crystal display is completed.
[0060]
FIG. 6 is a sectional view showing a transflective liquid crystal display according to a fourth embodiment of the present invention.
[0061]
In FIG. 6, in the transflective liquid crystal display, one of the pixels has two parts, that is, a transmissive region II and a reflective region I. The formation of the liquid crystal display is as follows.
[0062]
First, a thin film transistor 61 and a transparent insulating layer 621 are sequentially formed inside one transparent substrate 601. Here, the transparent insulating layer 621 may be, for example, a silicon oxide (SiOx) layer, a silicon nitride (SiNx) layer, or a laminate thereof.
[0063]
Next, the transmissive region II and the reflective region I are defined. A pad insulating layer 622 having a protrusion on the surface is formed at the position of the reflective region I. As the material of the pad insulating layer 622, a photosensitive resin, an insulating material that transmits light, or an insulating material that does not transmit light may be used.
[0064]
For example, the material of the pad insulating layer 622 is a photosensitive resin. In this case, the photosensitive resin is applied to the transparent substrate, and the reflection area is patterned by exposure / development.
[0065]
After the patterning of the transmissive region and the reflective region is completed, the transmissive electrode 64 and the reflective electrode 63 are formed. Here, the transmissive electrode 64 in the transmissive region II may be formed by depositing ITO or IZO by sputtering. The reflective electrode 63 in the reflective region I may be formed by forming aluminum (Al), silver (Ag), or an aluminum neodymium (AlBd) alloy by sputtering.
[0066]
Next, the pixel electrode is formed by electrically connecting the transmissive electrode 64 and the reflective electrode 63. The pixel electrode is electrically connected to the thin film transistor 61.
[0067]
On the other hand, after the color filter 65 is formed inside the other transparent substrate 602, the reflective region common electrode 66 and the transmissive region common electrode 67 are formed.
[0068]
The method of forming the electrodes includes a step of depositing a transparent insulating layer 68, a step of removing the transparent insulating layer corresponding to the reflective region I by photolithography and etching, a step of forming ITO or IZO by sputtering, And separating (electrically shutting off) both electrodes by lithography and etching.
[0069]
Since both electrodes are electrically cut off, when operating the liquid crystal display, by applying different voltages to the reflective region common electrode 66 and the transmissive region common electrode 67, the applied voltage in the reflective region and in the transmissive region are applied. The applied voltage can be adjusted so that the applied voltage is different. For this reason, since the TV curve and the RV curve do not overlap, the conventional problem that the saturation of the reflection region and the transmission region to which the same voltage is applied is different is solved.
[0070]
Finally, the transparent substrates 601 and 602 are aligned so that the inner surfaces of the transparent substrates 601 and 602 face each other, and liquid crystal is injected to form a liquid crystal layer 69. Here, the liquid crystal display is completed.
[0071]
FIG. 7 is a sectional view showing a transflective liquid crystal display according to a fifth embodiment of the present invention.
[0072]
In FIG. 7, in the transflective liquid crystal display, one of the pixels has two parts, that is, a transmissive region II and a reflective region I. The formation of the liquid crystal display is as follows.
[0073]
First, a thin film transistor 71 and a transparent insulating layer 721 are sequentially formed inside one transparent substrate 701. Here, the transparent insulating layer 721 may be, for example, a silicon oxide (SiOx) layer, a silicon nitride (SiNx) layer, or a laminate of these.
[0074]
Next, the transmissive region II and the reflective region I are defined. A pad insulating layer 722 having a protrusion on the surface is formed at the position of the reflective region I. As the material of the pad insulating layer 722, a photosensitive resin, an insulating material that transmits light, or an insulating material that does not transmit light may be used.
[0075]
For example, the material of the pad insulating layer 722 is a photosensitive resin. In this case, the photosensitive resin is applied to the transparent substrate, and the reflection area is patterned by exposure / development.
[0076]
After the patterning of the transmissive region and the reflective region is completed, the transmissive electrode 74 and the reflective electrode 73 are formed. Here, the transmissive electrode 74 in the transmissive region II may be formed by depositing ITO or IZO by sputtering. The reflective electrode 73 in the reflective region I can be formed by forming aluminum (Al), silver (Ag), or an aluminum neodymium (AlBd) alloy by sputtering.
[0077]
Next, a pixel electrode is formed by electrically connecting the transmissive electrode 74 and the reflective electrode 73. The pixel electrode is electrically connected to the thin film transistor 71.
[0078]
On the other hand, after the color filter 75 is formed inside the other transparent substrate 702, the reflective region common electrode 76 and the transmissive region common electrode 77 are formed.
[0079]
The method for forming the electrodes includes a step of forming ITO or IZO by sputtering, a step of depositing a transparent insulating layer 78, a step of removing the transparent insulating layer corresponding to the reflective region I by photolithography and etching, and sputtering. The method includes a step of depositing ITO or IZO by a method and a step of separating (electrically blocking) both electrodes by photolithography and etching.
[0080]
Since both electrodes are electrically cut off, when operating the liquid crystal display, different voltages are applied to the reflective region common electrode 76 and the transmissive region common electrode 77, respectively, so that the applied voltage in the reflective region and the transmissive region are The applied voltage can be adjusted so that the applied voltage is different. For this reason, since the TV curve and the RV curve do not overlap, the conventional problem that the saturation of the reflection region and the transmission region to which the same voltage is applied is different is solved.
[0081]
Finally, the transparent substrates 701 and 702 are aligned so that the inner surfaces of the transparent substrates 701 and 702 face each other, and liquid crystal is injected to form a liquid crystal layer 79. Here, the liquid crystal display is completed.
[0082]
Although the present invention has been presented as in the above embodiments, this is not intended to limit the present invention, and those skilled in the art can make variations and modifications within the spirit and scope of the present invention. Therefore, the scope of right of the present invention is equivalent to the scope of claims.
[0083]
【The invention's effect】
When operating the liquid crystal display, by applying different voltages to the reflective region common electrode and the transmissive region common electrode, the applied voltage can be adjusted so that the applied voltage in the reflective region is different from the applied voltage in the transmissive region. it can. For this reason, the saturation of the reflection area and the transmission area comes to coincide.
[Brief description of the drawings]
FIG. 1A is a diagram showing a liquid crystal alignment pattern when a voltage is not applied to a plus-type liquid crystal.
FIG. 1B is a diagram illustrating a liquid crystal alignment pattern when a voltage V1 is applied to a plus-type liquid crystal.
FIG. 2A is a diagram showing a TV curve and an RV curve.
FIG. 2B is a cross-sectional view showing a conventional transflective liquid crystal display.
FIG. 3 is a cross-sectional view showing a transflective liquid crystal display according to a first embodiment of the present invention.
FIG. 4 is a sectional view showing a transflective liquid crystal display according to a second embodiment of the present invention.
FIG. 5 is a cross-sectional view showing a transflective liquid crystal display according to a third embodiment of the present invention.
FIG. 6 is a sectional view showing a transflective liquid crystal display according to a fourth embodiment of the present invention.
FIG. 7 is a sectional view showing a transflective liquid crystal display according to a fifth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Liquid crystal layer 12 Pixel electrode 13 Common electrode 14 Liquid crystal 21 Transmission electrode 22 Reflection electrode 23 Common electrode 301,401,501,601,701 One transparent substrate 302,402,502,602,702 The other transparent substrate 31,41, 51, 61, 71 Thin film transistor 321, 421, 521, 621, 721 Transparent insulation layer 322, 422, 522, 622, 722 Pad insulation layer 33, 43, 53, 63, 73 Reflective electrode 34, 44, 54, 64, 74 Transmission electrode 35, 45, 55, 65, 75 Color filter 36, 46, 56, 66, 76 Reflection area common electrode 37, 47, 57, 67, 77 Transmission area common electrode 48, 58, 68, 78 Transparent insulating layer 39 , 49, 59, 69, 79 Liquid crystal layer

Claims (7)

A first substrate having a plurality of transmissive regions and a plurality of reflective regions;
A transmissive electrode located in the transmissive region;
A reflective electrode located in the reflective region and electrically connected to the transmissive electrode;
A plurality of first common electrodes provided at positions corresponding to the transmission region; and a plurality of second common electrodes provided at positions corresponding to the reflection region and electrically insulated from the first common electrode. A second substrate;
Ri Do and a liquid crystal layer located between the first substrate and the second substrate,
The distance between the first common electrode and the second substrate is different from the distance between the second common electrode and the second substrate .   2. The liquid crystal display device according to claim 1, wherein the first common electrode extends to an upper side corresponding to the reflection region.   The liquid crystal display device according to claim 1, wherein the second common electrode extends up to an upper portion corresponding to the transmission region.   The liquid crystal display device according to claim 1, wherein the first substrate and the second substrate are transparent substrates.   4. The liquid crystal display device according to claim 1, wherein the reflective electrode is made of a metal layer, and the material of the metal layer is any one of Al, Ag, and AlNd alloy.   The liquid crystal display device according to claim 1, wherein a distance between the first common electrode and the second substrate is shorter than a distance between the second common electrode and the second substrate.   The liquid crystal display device according to claim 1, wherein a distance between the first common electrode and the second substrate is longer than a distance between the second common electrode and the second substrate.

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