JP2014149546A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lateral electric field type liquid crystal display device that suppresses a display defect due to static electricity to be charged on a light shielding layer, and suppresses a leakage of light from backlight.SOLUTION: A normally black mode lateral electric field type liquid crystal display device 10 has: a first substrate 11 and a second substrate 28 that have a liquid crystal 43 encapsulated, and have a periphery adhered by sealant 36; a display area 37 formed on an inner side surrounded by the sealant 36 of both substrates 11 and 28 and a non-display area 38 formed in a periphery of the display area; a lower electrode 22 and an upper second electrode 24 that are formed on the first substrate 11; and a light shield layer 32 that is formed to extend over the display area 37 and the non-display area 38 of the second substrate 28. The light shield layer 32 has a light shield layer non-forming area 32a so as to surround the display area 37 in the non-display area 38, and the upper electrode 24 is connected to common electrode potential.

Description

  The present invention relates to a liquid crystal display device, and more particularly to a horizontal electric field type liquid crystal display device that suppresses display defects due to static electricity charged in a light shielding layer and further suppresses light leakage of a backlight.

  Generally, in a liquid crystal display device, a backlight as a light source is disposed on the side opposite to the display surface side of a liquid crystal display device including a pair of substrates, and light emitted from the backlight is transmitted through the liquid crystal display device. Thus, a desired image or video is displayed. At this time, since a light shielding layer is formed in a non-display area (also referred to as a frame area) that is the periphery of the display area of the liquid crystal display device, light leakage of the backlight can be suppressed.

  However, if the light shielding layer for suppressing light leakage is continuously formed up to the end of the second substrate having the color filter layer or the like, static electricity that has entered from the end of the light shielding layer passes through the light shielding layer to the display area. May penetrate. In particular, in a lateral electric field type liquid crystal display device operating in an FFS (Fringe Field Switching) mode or an IPS (In-Plane Switching) mode, a pair of electrodes for driving a liquid crystal is formed on a first substrate, and the color filter substrate is formed on the color filter substrate. Since no electrode for driving the liquid crystal is formed, the liquid crystal molecules in the display region are driven by static electricity that has entered the light shielding layer, which may cause display defects. Therefore, in order to prevent static electricity from entering from the end of the light shielding layer, the light shielding layer is divided in the non-display area. However, if the light shielding layer is divided, light leakage occurs from that portion. There is.

  In order to solve such a problem, the following Patent Document 1 discloses an invention of a lateral electric field type liquid crystal display device in which a portion where a black matrix around a display region cannot be arranged is shielded by a polarizing plate. That is, in the liquid crystal display device disclosed in Patent Document 1 below, a pixel electrode and a common electrode are formed on the surface of one transparent substrate on the liquid crystal layer side among the transparent substrates arranged to face each other with a liquid crystal layer interposed therebetween. A black matrix made of a resin composition is provided on the other transparent substrate, and the size of the outer periphery of the black matrix is smaller than the size of the opening region of the housing. The size of the at least one polarizing plate arranged in is larger than the size of the opening region of the housing.

  In the liquid crystal display device disclosed in the following Patent Document 1, since the polarizing plate is formed in a portion where the black matrix is not provided, the light leakage of the backlight can be blocked by the polarizing plate. It is said that the light leakage of the backlight in the region from the part to the housing can be surely prevented.

JP 09-258203 A

  However, in the invention described in Patent Document 1, the configuration for preventing the polarizing plate from being scratched by preventing the casing from directly contacting the polarizing plate is complicated, and the polarizing plate and the casing Need to be aligned with high accuracy.

  It is also conceivable to suppress light leakage by forming a wiring or the like formed of a metallic material on the first substrate side. However, in some cases, metal wiring or the like cannot be arranged on the first substrate side in order to narrow the frame around the pixel. In particular, when a liquid crystal display device is manufactured using a liquid crystal dropping (ODF: One Drop Fill) method, it is necessary to cure the sealing material made of a photocurable material by irradiating with ultraviolet rays. Since this light irradiation has to be performed from the first substrate side since the light shielding layer is formed on the second substrate, it is difficult to form a light shielding film for preventing light leakage on the array substrate side.

  The present inventors have adopted a configuration in which the light shielding layer is divided in the non-display area in order to suppress display defects due to static electricity charged in the light shielding layer formed across the display area and the non-display area. Various studies have been made to suppress light leakage from the divided region of the light shielding layer. As a result, the inventors have found that the problem can be solved by always displaying the liquid crystal in the divided region of the light shielding layer in the normally black mode, and have completed the present invention. That is, an object of the present invention is to provide a horizontal electric field type liquid crystal display device which suppresses display defects due to static electricity charged in the light shielding layer and also suppresses light leakage of the backlight in the horizontal electric field type liquid crystal display device. There is to do.

  In order to achieve the above object, a liquid crystal display device of the present invention is formed by sandwiching an insulating layer between a first substrate and a second substrate in which liquid crystal is sealed and a periphery is bonded with a sealing material. A normally black mode in which the liquid crystal is driven by an electric field generated between the upper electrode and the lower electrode, and the backlight source disposed on the outer side of the first substrate. A horizontal electric field type liquid crystal display device, which is a region formed on the inner side surrounded by the sealing material of the first substrate and the second substrate, and the upper electrode and the lower electrode overlap each other in plan view. A display region, a non-display region formed around the display region, and a light-shielding layer formed in the non-display region of the second substrate, wherein the light-shielding layer surrounds the display region surrounded by a sealing material A light-shielding layer having a light-shielding layer non-formation region where no layer is formed If has, the upper electrodes are connected to the common electrode potential.

  In the liquid crystal display device of the present invention, the non-light-shielding layer non-forming region where the light-shielding layer is not formed is formed in the non-display region of the second substrate so as to surround the display region. As a result, even if static electricity enters the light-shielding layer from the edge of the liquid crystal display device, the static electricity does not penetrate the light-shielding layer and enter the display area beyond the light-shielding layer non-formation region. The occurrence of defects is suppressed.

  In addition, in the liquid crystal display device of the present invention, the upper electrode extends to a position overlapping with all of the light shielding layer non-formation region in plan view. Since the upper electrode is connected to the common electrode potential, it becomes a reference potential with respect to the liquid crystal molecules, so that the liquid crystal molecules are not driven by the potential applied to the upper electrode. Therefore, in the liquid crystal display device of the present invention, the normally black mode is always maintained in the light shielding layer non-forming region, so that light from the backlight does not come out to the outside in the light shielding layer non-forming region, A horizontal electric field type liquid crystal display device with good contrast even in the peripheral region can be obtained.

  Note that the horizontal electric field type liquid crystal display device of the present invention overlaps each other in a plan view even in an FFS mode liquid crystal display device in which an upper electrode and a lower electrode formed with an insulating layer interposed therebetween overlap each other in a plan view. Even an IPS mode liquid crystal display device that is not applicable is equally applicable. Further, “planar view” in the present invention is used to mean a configuration when the liquid crystal display device is viewed from the display surface side of the liquid crystal display device.

  Further, in the liquid crystal display device of the present invention, since it is not necessary to provide a light shielding metal on the first substrate in the light shielding layer non-forming region, even in the liquid crystal display device manufactured by the ODF method, the light in the light shielding layer non-forming region is provided. Leakage can be suppressed.

  In the liquid crystal display device of the present invention, the light shielding layer is preferably formed of a metallic material.

  The metal light-shielding layer has a high light-shielding accuracy even if it is formed thinner than the resin light-shielding layer, but the display image quality is easily affected by external static electricity because of its high conductivity. For this reason, a resin-made light shielding layer is often used in a conventional horizontal electric field type liquid crystal display device. However, according to the liquid crystal display device of the present invention, since the non-light-shielding layer-free region is formed in the non-display region of the second substrate so as to surround the display region, the light-shielding layer is electrically conductive. Even if it is made of a metal with a high rate, static electricity that has entered from the outside is less likely to adversely affect the display image quality.

  In the liquid crystal display device of the present invention, the positioning mark may be formed so as to overlap with the upper electrode located in the light shielding layer non-forming region.

  In a conventional liquid crystal display device, a positioning mark used for bonding the first substrate and the second substrate is often behind the light shielding layer and is difficult to see. According to the liquid crystal display device of the present invention, the positioning mark is formed on the upper electrode located in the light shielding layer non-forming region. Since this positioning mark can be visually recognized through the light shielding layer non-formation region when the first substrate and the second substrate are bonded together, the bonding of the first substrate and the second substrate can be performed accurately and easily. This positioning mark is used when the liquid crystal display device is used because light is not transmitted through the region where the light shielding layer is not formed after the liquid crystal is sealed between the first substrate and the second substrate and the liquid crystal display device is completed. There is no fear of being visually recognized by a person.

  In the liquid crystal display device of the present invention, it is preferable that a plurality of positioning marks are formed.

  If a plurality of positioning marks are formed, the alignment accuracy is further improved, so that the effects of the present invention can be achieved better.

  In the liquid crystal display device of the present invention, the positioning mark is preferably formed of the same material as the electrode of the lower electrode driving switching element.

  If the positioning mark is formed of the same material as the electrode of the lower electrode driving switching element, it can be formed at the same time as the electrode of the lower electrode driving switching element. Therefore, it is necessary to use a process and material for forming the positioning mark separately. Disappears. Therefore, according to the liquid crystal display device of the present invention, the positioning mark can be formed without particularly increasing the number of manufacturing steps. In general, a thin film transistor (TFT) is used as a switching element for driving the lower electrode. In this case, the positioning mark is made of the same material as the gate electrode or the source electrode. That's fine.

It is a top view of the liquid crystal display device concerning Embodiment 1 and 2 of this invention. 3 is an enlarged plan view of one pixel region of the liquid crystal display devices of Embodiments 1 and 2. FIG. It is sectional drawing cut | disconnected by the III-III line of FIG. 4A is a cross-sectional view taken along line IVA-IVA of FIG. 1 in the liquid crystal display device of Embodiment 1, and FIG. 4B is an enlarged view of the IVB portion of FIG. FIG. 4B is a cross-sectional view corresponding to FIG. 4A showing when the liquid crystal display device of Embodiment 1 is driven. 6A is an enlarged view corresponding to FIG. 4B in the liquid crystal display device of Embodiment 2, and FIG. 6B is an enlarged view of a VIB portion of FIG. 6A.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the embodiments and the drawings. However, in the following embodiment, a lateral electric field type FFS mode liquid crystal display device will be described as an example in order to embody the technical idea of the electro-optical device of the present invention. The present invention is not intended to be specific to the FFS mode liquid crystal display device described in the above, and the present invention is equally applicable to other embodiments included in the claims. In each drawing used for the description in this specification, each layer and each member are displayed in different scales so that each layer and each member can be recognized on the drawing. However, it is not necessarily displayed in proportion to the actual dimensions.

[Embodiment 1]
First, the configuration of the liquid crystal display device 10 of Embodiment 1 will be described with reference to FIG. As shown in FIG. 1, the liquid crystal display device 10 of Embodiment 1 includes an array substrate 11 (corresponding to the “first substrate” of the present invention) in which various wirings are formed on a first transparent substrate 12 made of glass or the like. A color filter substrate 28 (corresponding to the “second substrate” of the present invention) in which a color filter layer or the like is formed on a second transparent substrate 29 made of glass or the like is disposed oppositely. The array substrate 11 and the color filter substrate 28 are bonded together by a sealing material 36, and a liquid crystal 43 (see FIG. 3) is sealed in a space formed by the sealing material 36. Further, a portion (see FIGS. 2 and 3) formed so that the inner lower electrode 22 and the upper electrode 24 surrounded by the sealing material 36 overlap in a plan view becomes a display region 37, and the outer peripheral side and the seal The outer peripheral side of the material 36 is a non-display area 38 (also referred to as “frame area”). Note that a liquid crystal 43 is disposed in the inner display area 37 and non-display area 38 surrounded by the sealing material.

  The array substrate 11 has a size slightly larger than that of the color filter substrate 28 so that a protruding portion of a predetermined space is formed when the array substrate 11 is arranged opposite to the color filter substrate 28. This overhanging portion is a mounting region 12a in which a driver IC 42 for driving the liquid crystal 43 and the like are disposed. In the liquid crystal display device 10 according to the first embodiment, an example in which the liquid crystal injection port 39 is formed by the sealing material 36 and the liquid crystal injection port 39 is sealed by the sealing material 40 is shown.

  Next, the configuration of each substrate will be described with reference to FIGS. First, a plurality of scanning lines 13 including gate electrodes G made of, for example, Mo / Al two-layer wiring are formed on the surface of the first transparent substrate 12 on the array substrate 11 so as to be parallel to each other. A gate insulating film 15 made of a transparent insulating material such as silicon nitride or silicon oxide is coated over the entire surface of the first transparent substrate 12 on which the scanning lines 13 are formed. Further, a semiconductor layer 16 made of, for example, an amorphous silicon layer is formed in a region where the TFT 20 as a switching element is formed on the surface of the gate insulating film 15. The region of the scanning line 13 at the position where the semiconductor layer 16 is formed forms the gate electrode G of the TFT 20.

  Further, on the surface of the gate insulating film 15, a signal line 14 and a drain electrode D including a source electrode S made of a conductive layer having a three-layer structure of, for example, Mo / Al / Mo are formed. Both the source electrode S portion and the drain electrode D portion of the signal line 14 partially overlap the surface of the semiconductor layer 16. The entire surface of the array substrate 11 is covered with a passivation film 17 made of a transparent insulating material such as silicon nitride or silicon oxide. Further, the entire surface of the passivation film 17 is covered with an interlayer film 21 made of, for example, a resin material, and contact holes 26 are formed in the passivation film 17 and the interlayer film 21 at positions corresponding to the drain electrodes D.

  Then, on the interlayer film 21 in a region surrounded by the scanning lines 13 and the signal lines 14 (hereinafter referred to as “pixel region 41”), for example, ITO (Indium Thin Oxide) or IZO so as to have the pattern shown in FIG. The lower electrode 22 is formed of a transparent conductive material made of (Indium Zinc Oxide). The lower electrode 22 is electrically connected to the drain electrode D through a contact hole 26. Therefore, the lower electrode 22 operates as a pixel electrode. Further, an interelectrode insulating film 23 is formed on the lower electrode 22. For the interelectrode insulating film 23, a transparent insulating material having good insulating properties such as silicon nitride is used.

  On the interelectrode insulating film 23, the upper electrode 24 is formed of a transparent conductive material made of ITO or IZO having a plurality of, for example, bar-shaped slits 25 in a plan view in the pixel region 41. A predetermined alignment film (not shown) is formed over the entire surface of the substrate. The upper electrode 24 is formed over the entire display area 37 and is electrically connected to a common wiring (not shown) in the non-display area 38. Therefore, the upper electrode 24 operates as a common electrode. As shown in FIGS. 1 and 4A, the upper electrode 24 is formed with an upper electrode extending portion 24a extending in the direction of the non-display region 38 with respect to the lower electrode 22.

  Further, as shown in FIG. 3, the color filter substrate 28 corresponds to the scanning line 13, the signal line 14, the TFT 20, and the non-display area 38 of the array substrate 11 on the surface of the second transparent substrate 29 made of a glass substrate or the like. A light shielding layer 32 is formed so as to cover the position. The light shielding layer 32 formed in the non-display area 38 is formed up to the end 32b of the color filter substrate 28 by, for example, a thin film made of chromium metal, and further the light shielding so as to surround the display area 37 in the non-display area 38. A light shielding layer non-formation region 32a in which the layer 32 is not formed is provided (see FIG. 1). The light shielding layer non-forming region 32a is formed at a position overlapping the upper electrode extension 24a formed on the array substrate 11 in plan view. The detailed configuration of the light shielding layer non-forming region 32a will be described later.

  On the surface of the second transparent substrate 29 on which the light shielding layer 32 is formed, a color filter layer 33 composed of a plurality of colors, for example, three colors of red, green, and blue, is formed. Further, an overcoat layer 34 made of a transparent resin is formed so as to cover the surfaces of the light shielding layer 32 and the color filter layer 33. An alignment film (not shown) is formed on the surface of the overcoat layer 34 over the entire surface of the color filter substrate 28. Further, polarizing plates 27 and 35 arranged in crossed Nicols are provided on the outer surfaces of the array substrate 11 and the color filter substrate 28, respectively. Therefore, the liquid crystal display device 10 operates in a normally black mode.

  Then, a sealing material 36 is applied to one of the array substrate 11 and the color filter substrate 28 and bonded. Thereafter, the liquid crystal 43 is injected from the liquid crystal injection port 39 formed by the sealing material 36, the liquid crystal injection port 39 is sealed by the sealing material 40, and the driver IC 42 and the like are installed in the mounting region 12a. The liquid crystal display device 10 is obtained.

  Next, a detailed configuration of the light shielding layer non-forming region 32a formed on the color filter substrate 28 and the upper electrode extending portion 24a formed on the array substrate 11 will be described with reference to FIGS.

  As shown in FIGS. 4A and 4B, in the liquid crystal display device 10 of the first embodiment, the light shielding layer 32 is formed up to the end portion 32b of the color filter substrate 28, and the display area 37 is formed in the non-display area 38. A light shielding layer non-forming region 32a where the light shielding layer 32 is not formed is provided so as to surround. On the other hand, the array substrate 11 is formed with an upper electrode extending portion 24 a that extends in the direction of the non-display area 38 compared to the lower electrode 22. And this light shielding layer non-formation area | region 32a and the upper electrode extension part 24a are formed so that it may overlap with planar view.

  With this configuration, even when static electricity enters from the end portion 32b of the light shielding layer 32 of the liquid crystal display device 10, the static electricity does not enter the display region 37 beyond the light shielding layer non-formation region 32a. Therefore, the occurrence of display defects is suppressed.

  Furthermore, in the liquid crystal display device 10 according to the first embodiment, the upper electrode 24 extends to a position overlapping with all of the light shielding layer non-forming region 32a in plan view. In the liquid crystal display device 10 according to the first embodiment, the potential of the upper electrode 24 becomes a reference potential with respect to the liquid crystal molecules, so that the liquid crystal molecules are not driven by the potential applied to the upper electrode 24. Therefore, as shown in FIG. 5, the normally black mode is always maintained in the non-light-shielding layer non-forming region 32a, and the black display 44 is obtained. Therefore, light is transmitted from the non-light-shielding layer non-forming region 32a shown in FIG. A liquid crystal display device with good contrast in the peripheral region can be obtained without going out.

  The light shielding layer 32 is generally made of resin or metal. However, the light shielding layer made of metal has a higher light shielding accuracy even if formed thinner than the resin light shielding layer. preferable. Therefore, in the liquid crystal display device 10 of Embodiment 1, even if the light shielding layer 32 is made of metal, the metal light shielding layer 32 has a problem that static electricity easily enters the display region 37. This is solved by forming the light shielding layer non-forming region 32a in the light shielding layer 32 of the non-display region 38, so that display defects due to static electricity entering from the light shielding layer 32 at the end of the liquid crystal display device 10 can be suppressed. Become.

[Embodiment 2]
Next, the liquid crystal display device 10 ′ according to the second embodiment will be described with reference to FIGS. 1 to 3 and FIG. Note that the liquid crystal display device 10 ′ of the second embodiment is obtained by forming marks on the upper electrode extension portion 24a with respect to the liquid crystal display device 10 of the first embodiment, and is common to the liquid crystal display device 10 of the first embodiment. Components are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIGS. 6A and 6B, in the liquid crystal display device 10 ′ of the second embodiment, a positioning mark 45 is formed so as to overlap with the upper electrode extension 24a formed on the array substrate 11. The positioning mark 45 is formed at a position that is visible from the light shielding layer non-forming region 32 a formed on the color filter substrate 28. The positioning mark 45 can be formed simultaneously using the same material when forming the gate electrode G or the source electrode S of the TFT 20 formed in the display region 37 of the array substrate 11.

  With such a configuration, the positioning mark 45 formed at the position overlapping the upper electrode extension 24 a extending to the light shielding layer non-forming region 32 a is not formed on the light shielding layer formed on the color filter substrate 28. Since it can be visually recognized from the formation region 32a, the substrates can be easily bonded together, and the accuracy of the bonding between the array substrate 11 and the color filter substrate 28 can be improved. Further, the positioning mark 45 is such that when the liquid crystal 43 is sealed between the array substrate 11 and the color filter substrate 28 and the liquid crystal display device 10 is driven, this portion is always displayed in black. There is no fear of being visually recognized by the user when 10 ′ is used.

  A plurality of positioning marks 45 may be formed. When a plurality of positioning marks 45 are formed, the alignment accuracy is further increased. Further, in the liquid crystal display device 10 ′ of the second embodiment, the positioning mark 45 is formed in a cross shape. However, the shape is not limited to this, and any shape may be used as long as the alignment can be confirmed. Can be adopted.

  In addition, although the liquid crystal display device of Embodiment 1 and 2 demonstrated the case where it manufactured by the vacuum injection method from the liquid crystal injection port which formed the liquid crystal with the sealing material, it is not restricted to this, Even when manufactured using the ODF method Can be applied. Since the irradiation of the ultraviolet rays for curing the sealing material made of the photocurable material is performed from the array substrate, it is usually impossible to form a light shielding layer on the array substrate side. In the liquid crystal display device of the present invention, since light can be shielded without providing a light shielding metal on the array substrate in the light shielding layer non-formation region, light leakage in the light shielding layer non-formation region can be achieved even in a liquid crystal display device manufactured by the ODF method. Can be suppressed.

  Further, as the liquid crystal display devices of Embodiments 1 and 2, the case of the FFS mode liquid crystal display device has been described as an example. However, if an insulating layer is formed between the upper electrode and the lower electrode, IPS The present invention is equally applicable to the mode liquid crystal display device. Further, in the liquid crystal display devices according to the first and second embodiments, the case where the switching element for driving the lower electrode is a thin film transistor TFT has been described. It is.

DESCRIPTION OF SYMBOLS 10, 10 ': Liquid crystal display device 11: Array substrate 12: 1st transparent substrate 12a: Mounting area 13: Scanning line 14: Signal line 15: Gate insulating film 16: Semiconductor layer 17: Passivation film 20: TFT 21: Interlayer film 22: Lower electrode 23: Interelectrode insulating film 24: Upper electrode 24a: Upper electrode extension 25: Slit 26: Contact hole 27: Polarizing plate 28: Color filter substrate 29: Second transparent substrate 32: Light shielding layer 32a: Light shielding Layer non-formation region 32b: End 33: Color filter layer 34: Overcoat layer 35: Polarizing plate 36: Sealing material 37: Display region 38: Non-display region 39: Liquid crystal injection port 40: Sealing material 41: Pixel region 42 : Driver IC 43: Liquid crystal 44: Black display 45: Positioning mark S: Source electrode D: Drain power G: gate electrode

Claims (5)

A first substrate and a second substrate in which liquid crystal is sealed and a periphery thereof is bonded with a sealing material; an upper electrode and a lower electrode formed with an insulating layer sandwiched between the first substrate; and the first substrate A normally black mode lateral electric field type liquid crystal display device, wherein the liquid crystal is driven by an electric field generated between the upper electrode and the lower electrode. ,
A region formed on the inner side of the first substrate and the second substrate surrounded by the sealing material, wherein the upper electrode and the lower electrode overlap in a plan view in the region;
A non-display area formed around the display area;
A light-shielding layer formed in the non-display area of the second substrate, the light-shielding layer non-formation area in which the light-shielding layer is not formed so as to surround the display area inside the seal material A light shielding layer;
Have
The upper electrode is connected to a common electrode potential;
Liquid crystal display device. The light shielding layer is formed of a metallic material,
The liquid crystal display device according to claim 1. A positioning mark is formed so as to overlap with the upper electrode located in the light shielding layer non-formation region,
The liquid crystal display device according to claim 1. A plurality of the positioning marks are formed,
The liquid crystal display device according to claim 3. The positioning mark is made of the same material as the electrode of the switching element for driving the lower electrode,
The liquid crystal display device according to claim 3.

Images