JP4501933B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device in which a pixel electrode and a common electrode for driving liquid crystal sandwiched between a first substrate and a second substrate facing each other are provided on a first substrate.

  In an FFS (Fringe Field Switching) mode liquid crystal panel, both a pixel electrode for controlling the alignment of liquid crystal and a common electrode are provided on an element substrate, and these two electrodes are stacked via an insulating film. Among the electrodes, the upper electrode is provided with a slit. When the rubbing process is performed substantially parallel to the long side direction of the slit and the potential between the electrodes is an off potential, the liquid crystal molecules are aligned substantially parallel to the long side direction of the slit. When a potential larger than the off potential is applied between the electrodes, an electric field (lateral electric field) is generated in a direction perpendicular to the long side of the slit, and the liquid crystal molecules are in a plane parallel to the substrate along the direction of the electric field. Rotate with (rotate horizontally). The amount of transmitted light is controlled by controlling the rotation angle of the liquid crystal molecules.

  In addition to the FFS mode, an IPS (In-Plane Switching) mode is known as a structure in which both the pixel electrode and the common electrode are provided on the element substrate.

JP-A-9-105918

  Liquid crystal panels have been reduced in size, thickness, and frame size, and functions such as touch panels have been added. As a result, static electricity from the outside of the panel due to the human body or the like may cause malfunction of the panel.

  For example, in the FFS mode or the like, when static electricity is applied to the counter substrate disposed opposite to the element substrate and the counter substrate is charged, a vertical electric field is generated by the charging, and the liquid crystal alignment by the electrodes of the element substrate is performed. There are cases where control cannot be performed properly. In this case, for example, in a normally black liquid crystal panel, the black display is whitened (whited) and the contrast is lowered. Further, display unevenness is observed when the degree of whitening is not uniform across the entire screen.

  As one of the countermeasures, a transparent conductive film is formed on the entire outer surface of the counter substrate, and the transparent conductive film is connected to a housing or an FPC (Flexible Printed Circuit) terminal, so that the above-described charging is connected to the ground potential of the external circuit ( There is a method of escaping to GND) (see Patent Document 1).

  However, it has been found that even with the above measures, sufficient electrostatic withstand voltage may not be obtained.

  An object of the present invention is to improve the electrostatic withstand voltage of a liquid crystal display device in which a pixel electrode and a common electrode for driving a liquid crystal sandwiched between a first substrate and a second substrate facing each other are provided on the first substrate. is there.

The liquid crystal display device according to the present invention is a liquid crystal display device in which a pixel electrode and a common electrode for driving liquid crystal sandwiched between a first substrate and a second substrate facing each other are provided on the first substrate, The first substrate includes a circuit wiring disposed outside a pixel region in which a plurality of pixels including the pixel electrode and the common electrode are disposed , a peripheral circuit, and a wiring for a predetermined potential to which a predetermined potential is applied, The second substrate includes a translucent conductive film disposed on the opposite side of the liquid crystal so as to face the pixel electrode and the common electrode and held at the predetermined potential, and the translucent conductive film includes the circuit An outer edge located closer to the center of the second substrate than the wiring and the peripheral circuit, and a leading portion extending toward the wiring for the predetermined potential, and is connected to the wiring for the predetermined potential via the leading portion; Drawer part The second is formed only on one side of the substrate, the predetermined potential wiring is characterized in that it is formed without overlap to the circuit wiring only in the one side of the first substrate.

Here, the circuit wiring is preferably power supply wiring. Further, it is preferable that the predetermined potential wiring is located on the outermost side of the terminal portion on one side of the first substrate.

  With the above structure, the influence of static electricity that has entered the light-transmitting conductive film on the circuit wiring of the first substrate can be reduced, so that static electricity resistance can be improved.

  Before describing the embodiments of the present invention, the electrostatic resistance was considered based on various evaluations. This will be described with reference to cross-sectional views of the periphery of the liquid crystal display device shown in FIGS. .

  As shown in FIGS. 6 and 7, in the conventional liquid crystal display device 10Z in the FFS mode, the first substrate 100Z and the second substrate 200Z are bonded together by a seal 304Z, and the liquid crystal 302Z is sandwiched between the substrates 100Z and 200Z. Has been. A circuit wiring group 104Z is disposed on the support substrate 102Z of the first substrate 100Z, and an insulating film 114Z is disposed to cover the circuit wiring group 104Z. In the drawing, the circuit wiring group 104Z is schematically shown. A translucent conductive film 208Z is disposed on the outer surface of the support substrate 202Z of the second substrate 200Z, and the translucent conductive film 208Z is disposed on the entire outer surface, that is, the outer edge of the support substrate 202Z, that is, the second edge. It extends to the outer edge of the substrate 200Z. For example, the translucent conductive film 208Z is formed on the entire surface of the multi-piece substrate and the substrate is divided, so that the translucent conductive film 208Z is formed up to the outer edge of the second substrate 200Z.

  When air discharge was performed on the light-transmitting conductive film 208Z, air discharge generated from the outer edge of the light-transmitting conductive film 208Z was observed as shown in FIG. 6 and connected to the circuit wiring group 104Z and this. Destruction was observed in the device. According to this, it is considered that static electricity propagated from the outer edge portion of the translucent conductive film 208Z to the circuit wiring group 104Z over the substrate side surface of the outer edge portion of the second substrate 200Z. In this case, it is considered that static electricity is more likely to propagate in the circuit wiring group 104Z that is closer to the outer edge of the substrate.

  In addition, destruction was also observed in the circuit wiring away from the outer edge of the substrate and the elements connected thereto. This breakdown is caused by the potential of the light-transmitting conductive film 208Z rising due to static electricity that has entered the light-transmitting conductive film 208Z, and coupled to this potential increase (capacitively coupled) to the potential of the circuit wiring group 104Z. It is thought to happen by rising. In other words, it is considered to be caused by the propagation of static electricity due to coupling (see FIG. 7). In FIG. 7, the state of the coupling is schematically shown by a graphic symbol of the capacitor. Coupling with the light-transmitting conductive film 208Z is more likely to occur as the area of the wiring pattern is larger, that is, as the width or length of the wiring is larger. For example, a power supply wiring that is formed with a wider line width to reduce resistance It is thought that it is easy to occur between.

  It was also found that the circuit wiring extending along the outer edge of the substrate is more likely to break than the circuit wiring extending in the direction intersecting the outer edge of the substrate.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a schematic diagram of a liquid crystal display device 10 according to an embodiment. Further, FIG. 2 shows a plan view of a portion 2 surrounded by an alternate long and short dash line in FIG. 1, FIG. 3 shows a cross-sectional view taken along a line 3-3 in FIG. FIG. 4 is a plan view of FIG. 4, and FIG. 5 is a sectional view taken along line 5-5 in FIG. For easy understanding of the drawings, some elements shown in other drawings are omitted in each drawing, and some elements are hatched in the plan view.

  As shown in FIG. 1, the liquid crystal display device 10 includes a liquid crystal panel 12, a casing 14 for the liquid crystal panel 12, an FPC 16, and an external circuit 18. The liquid crystal panel 12 is connected to the external circuit 18 via the FPC 16. Various wiring bodies can be used instead of the FPC 16. Here, a case where the liquid crystal panel 12 is in the FFS mode is illustrated. The liquid crystal panel 12 may be any of a transmissive type, a reflective type, and a transflective type.

  The liquid crystal panel 12 includes a first substrate 100, a second substrate 200, a liquid crystal 302, and a seal 304. The substrates 100 and 200 face each other with a predetermined gap, and are bonded together by a seal 304 at the peripheral edge. A liquid crystal 302 is sandwiched in a container including the substrates 100 and 200 and the seal 304.

  The first substrate 100 includes a support substrate 102 formed of a light-transmitting substrate such as glass, for example. 110, 112, a common electrode 116, and a pixel electrode 118.

  The common electrode 116 and the pixel electrode 118 are paired to control the orientation of the liquid crystal 302, that is, an electrode that drives the liquid crystal 302. The common electrode 116 is provided in common for a plurality of pixels, and the pixel electrode 118 is provided for each pixel, and a potential corresponding to the display of the pixel is supplied. Note that the common electrode 116 may be provided for each pixel so that a common potential is supplied. That is, a plurality of pixels are configured by the plurality of pixel electrodes 118 and at least one common electrode 116. In the FFS mode liquid crystal panel 12, both electrodes 116 and 118 are provided on the first substrate 100, and the electrodes 116 and 118 are stacked with an insulating film 112 interposed therebetween. Here, the case where the pixel electrode 118 is disposed on the upper layer, that is, the liquid crystal 302 side is illustrated, but the common electrode 116 may be disposed on the upper layer. The upper pixel electrode 118 is provided with a slit (not shown), and the orientation of the liquid crystal 302 is controlled by an electric field generated between the electrodes 116 and 118 through the slit. The electrodes 116 and 118 are made of a light transmitting conductive film such as ITO (Indium Tin Oxide).

  Although FIG. 2 illustrates the case where the pixel electrodes 118 are arranged in a matrix, that is, the case where the pixels are arranged in a matrix, the pixels may be arranged in a delta arrangement, for example. Note that one or more pixels located at the outermost periphery may be used as dummy pixels that do not directly contribute to display.

  The circuit wirings 104 and 106 and the peripheral circuit 108 are arranged outside the pixel region. Here, the pixel area is an area where a plurality of pixels are arranged, in other words, a plurality of pixels are arranged in the pixel area. The dummy pixel region is also included in the pixel region. The circuit wirings 104 and 106 are wirings constituting a driving circuit or the like provided in the liquid crystal panel 12, and are various power supply wirings, for example. Here, the circuit wirings 104 and 106 are wirings that extend along the outer edge of the first substrate 100, and extend along one or more sides of the outer edge. The length of the circuit wirings 104 and 106 is, for example, larger than the width of the area outside the pixel area. Although the peripheral circuit 108 is schematically illustrated, the peripheral circuit 108 includes, for example, a driver circuit that supplies a potential to the pixel electrode 118. Note that details of the connection between the peripheral circuit 108 and the circuit wirings 104 and 106, the connection between the peripheral circuit 108 and the electrodes 116 and 118, and the like can be applied to various general configurations, and the description thereof is omitted here.

  In the drawing, the circuit wiring 104 is positioned on the outer edge side of the first substrate 100 with respect to the circuit wiring 106, and the peripheral circuit 108 is disposed between the circuit wirings 104, 106. It is not limited to. For example, even in the first substrate 100, there may be a location where one or more of the elements 104, 106, and 108 are not provided depending on the position. Further, although the two circuit wirings 104 and 106 are illustrated, the number of circuit wirings is not limited to this, and one or both of the circuit wirings 104 and 106 may be plural.

  The insulating films 110 and 112 are made of, for example, silicon oxide, silicon nitride, or the like, and are stacked on the support substrate 102. For ease of explanation, the case where the insulating film 110 is formed below the common electrode 116, that is, the supporting substrate 102 side, and the insulating film 112 is stacked on the insulating film 110 is illustrated. The films 110 and 112 are collectively referred to as an insulating film 114. Each of the insulating films 110 and 112 may be a single layer film or a multilayer film.

  3 illustrates the case where the circuit wirings 104 and 106 and the peripheral circuit 108 are in contact with the support substrate 102 and covered with the insulating film 110, one or more of these elements 104, 106, and 108 are illustrated. May be embedded in an insulating film 114 formed of a multilayer film so as not to contact the support substrate 102.

  The second substrate 200 includes a support substrate 202 made of a light-transmitting substrate such as glass, and includes a light shielding film 204 and a color filter 206 on the inner surface side of the support substrate 202, that is, the liquid crystal 302 side. A translucent conductive film 208 is included on the outer surface side of 202, that is, on the side opposite to the liquid crystal 302. In FIG. 2, the translucent conductive film 208 is indicated by a one-dot chain line.

  The support substrate 202 is disposed to face the first substrate 100 and has a size facing the electrodes 116 and 118, the circuit wirings 104 and 106, and the peripheral circuit 108. The light shielding film 204 extends over the entire surface of the support substrate 202 and has an opening at a position facing the pixel electrode 118. Note that no opening is provided in a portion facing the dummy pixel. The light shielding film 204 is made of, for example, a resin containing a black pigment. The color filter 206 is disposed on the support substrate 202, is provided in the opening of the light shielding film 204, and faces the electrodes 116 and 118.

  The translucent conductive film 208 is disposed on the outer surface of the support substrate 202 and faces the electrodes 116, 118 and the like through the substrate 202. The translucent conductive film 208 is held at an arbitrary predetermined potential, for example, a ground potential, and releases static electricity that enters the second substrate 200 from the outside of the panel to prevent the second substrate 200 from being charged. That is, the translucent conductive film 208 serves as a shield film. Thereby, the malfunction by the charge of the 2nd board | substrate 200, for example, the fall of contrast and display nonuniformity, can be suppressed.

The translucent conductive film 208 is made of, for example, ITO, and may be made of either an inorganic material or an organic material, such as a sputtering method, a plasma CVD (Chemical Vapor Deposition) method, a spin coating method, a printing method, or the like. It can be formed by this method. The resistivity (sheet resistance) of the translucent conductive film 208 is, for example, 10 ⁵ Ω / □, and the lower the better. The translucent conductive film 208 includes a main body portion 208a and a lead portion 208b (see FIG. 4).

  A main body portion 208 a of the translucent conductive film 208 is disposed to face the common electrode 116 and the pixel electrode 118. The main body portion 208 a extends in the center of the support substrate 202, but its outer edge does not reach the outer edge of the support substrate 202, that is, the outer edge of the second substrate 200. The outer edge of the main body portion 208a is located closer to the center of the substrate than the circuit wirings 104 and 106 and the peripheral circuit 108, and the main body portion 208a does not face these elements 104, 106, and 108. Here, a case where the entire circumference of the outer edge of the main body portion 208a is located closer to the center of the board than the outer edge of the second board 200 is located closer to the center of the board than the circuit wirings 104 and 106 and the peripheral circuit 108. The main body portion 208a may be provided without being patterned (with no gaps), or may be patterned, for example, in a mesh pattern as long as it has a shielding effect against static electricity. Further, the shape of the main body portion 208a is not limited to the illustrated example.

  Here, FIG. 3 illustrates a case where the outer edge of the main body portion 208a is aligned with the outer edge of the common electrode 116 and the outermost edge of the outermost pixel electrode 118, and FIG. The case where it protrudes to the board | substrate outer edge side rather than the outer edge is illustrated. When the dummy pixel is provided, the main body portion 208a may be provided up to a position facing the electrodes 116 and 118 of the dummy pixel, or the main body portion 208a may be provided inside the dummy pixel.

  The lead-out portion 208b of the translucent conductive film 208 extends from the main body portion 208a toward the outer edge on the terminal portion side of the liquid crystal panel 12 in the outer edge of the support substrate 202. Note that the terminal portion of the liquid crystal panel 12 is provided in a portion of the first substrate 100 that does not overlap the second substrate 200, and the terminal portion is provided with a connection terminal to the FPC 16, and the like. Here, FIG. 5 illustrates a case where the lead-out portion 208b reaches the outer edge of the support substrate 202, and FIG. 4 illustrates a case where the lead-out portion 208b does not reach the outer edge.

  The translucent conductive film 208 is connected to a predetermined potential, for example, a ground potential via the lead portion 208b. An example of this connection form will be described below with reference to FIGS.

  The first substrate 100 is configured to include a wiring 140 for connection to the predetermined potential, an insulating film 142, and conductive portions 144 and 146 in the terminal portion.

  One end of the wiring 140 is provided in the vicinity of the boundary between the overlapping portion of the substrates 100 and 200 and the terminal portion, and the other end is provided at the end of the terminal portion. The wiring 140 preferably avoids coupling with other wirings to avoid coupling. Although FIG. 4 illustrates the case where the wiring 140 is positioned on the outermost side in the terminal portion, it may be provided at another position. Further, the plane pattern of the wiring 140 is not limited to the illustrated example. Although FIG. 5 illustrates the case where the wiring 140 is in contact with the support substrate 202, for example, the wiring 140 may be embedded in the insulating film 142 so as not to contact the support substrate 202. The wiring 140 can be formed simultaneously with the various wirings by patterning in the case where the wiring 140 is made of the same material as the other wirings of the terminal portion and the circuit wirings 104 and 106 (see FIG. 2). According to such simultaneous formation, the wiring 140 can be formed without increasing the number of manufacturing steps.

  The insulating film 142 is disposed on the support substrate 202 so as to cover the wiring 140. The insulating film 142 can be configured using, for example, any one of the insulating films 110, 112, and 114 (see FIG. 3). The insulating film 142 is provided with contact holes reaching the one end and the other end of the wiring 140.

  The conducting portion 144 is connected to the one end portion of the wiring 140 through the contact hole and reaches the insulating film 142 near the contact hole. The conducting portion 146 is connected to the other end portion of the wiring 140 through the contact hole and reaches the insulating film 142 near the contact hole. In addition, illustration of the conduction | electrical_connection part 146 is abbreviate | omitted in FIG. Here, the conducting portions 144 and 146 correspond to so-called pad electrodes. In order to avoid coupling, the conducting portions 144 and 146 are preferably arranged so as to avoid overlapping with other wirings other than the wiring 140. It is preferable that the conductive portions 144 and 146 cover the wiring 140 together with the insulating film 142, thereby preventing the wiring 140 from being exposed to the outside and protecting it from the external environment.

  The conductive portions 144 and 146 are made of, for example, ITO, and can be formed without increasing the number of manufacturing steps by patterning simultaneously with the pixel electrode 118, for example. The liquid crystal panel 12 further includes a connection body 306 externally attached to the substrates 100 and 200. Here, the connection body 306 is disposed on the lead portion 208 b of the translucent conductive film 208, reaches the first substrate 100 along the side surface of the second substrate 200, and is disposed on the conductive portion 144. Thereby, the translucent conductive film 208 is connected to the wiring 140 through the connection body 306 and the conduction part 144. In this case, the connection body 306 can be shortened by extending the lead-out portion 208 b of the translucent conductive film 208 toward the wiring 140. It is preferable that the connection body 306 covers the entire conductive portion 144 to prevent the conductive portion 144 from being exposed to the outside, thereby protecting the conductive portion 144 from the external environment (see FIGS. 4 and 5). In addition, the connection body 306 is preferably arranged so as to avoid overlapping with other wirings other than the wiring 140 in order to avoid coupling.

  The connection body 306 can be formed by applying and curing a conductive paste such as silver paste or carbon paste. When the conductive paste is used, the connection body 306 can be easily formed by application and curing. The connection body 306 preferably has a lower resistivity than the translucent conductive film 208. Further, the connection body 306 is preferably thinner than other elements on the outer surface of the support substrate 202, such as a polarizing plate (not shown), so that the connection body 306 does not hinder the thinning of the liquid crystal display device 10. .

  The liquid crystal display device 10 includes an ACF (Anisotropic Conductive Film) 22 between the FPC 16 and the conductive portion 146, and the wiring 16 a and the wiring 140 of the FPC 16 are electrically connected by the ACF 22. ing. The ACF 22 may be provided only for the wirings 16 a and 140, or may be used to connect the other wiring of the terminal portion to the FPC 16. In the liquid crystal display device 10, the wiring 16 a of the FPC 16 is connected to a predetermined potential, whereby the translucent conductive film 208 is formed through the wiring 16 a, the ACF 22, the conductive portion 146, the wiring 140, the conductive portion 144, and the connection body 306. Connected to a predetermined potential. FIG. 1 illustrates the case where the predetermined potential is the ground potential in the external circuit 18. In order to protect from the external environment, it is preferable to prevent the conductive portion 146 and the wiring 16a from being covered with the ACF 22 and exposed to the outside.

  According to the above configuration, the main body portion 208 a of the translucent conductive film 208 is provided inside the outer edge of the support substrate 202. For this reason, compared with the case where the translucent conductive film 208Z spreads over the entire surface of the support substrate 202Z as in the conventional liquid crystal display device 10Z, the outer peripheral portion of the translucent conductive film 208 extends over the side surface of the support substrate 202. A route that extends beyond the first substrate 100 to the circuit wiring 104 or the like becomes longer. Accordingly, even when static electricity enters the light-transmitting conductive film 208, propagation of static electricity through the path can be suppressed. Thereby, static electricity tolerance can be improved.

  Further, since the main body portion 208a of the translucent conductive film 208 is not opposed to the circuit wirings 104, 106 and the like of the first substrate 100, coupling between the translucent conductive film 208 and the circuit wirings 104, 106 and the like is avoided. Has been. For this reason, even when static electricity enters the translucent conductive film 208, it is possible to suppress static electricity from being transmitted from the translucent conductive film 208 to the circuit wirings 104, 106, and the like by coupling. Thereby, static electricity tolerance can be improved.

  In view of the above evaluation that static electricity easily propagates to the circuit wiring extending along the outer edge of the substrate, the translucent conductive film 208 can more reliably improve static electricity resistance.

  Here, the case where the translucent conductive film 208 is in contact with the outer surface of the support substrate 202 is illustrated above. However, for example, an insulating film is provided between the translucent conductive film 208 and the support substrate 202. Examples of the insulating film include optical films such as a polarizing plate, a retardation plate, an optical compensation plate, a brightness enhancement film, and an antireflection film.

  In the above description, the FFS mode in which the electrodes 116 and 118 for driving the liquid crystal 302 are stacked via the insulating film 112 is illustrated. However, the electrodes 116 and 118 are disposed in the same layer (for example, on the insulating film 112). It is also possible to configure the IPS mode. In the case of the IPS mode, for example, the electrodes 116 and 118 having a comb-shaped pattern are arranged in a form in which the comb-shaped shapes are engaged with each other.

1 is a schematic diagram of a liquid crystal display device according to an embodiment of the present invention. It is a top view of the part 2 enclosed with the dashed-dotted line in FIG. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2. It is a top view of the part 4 enclosed with the dashed-dotted line in FIG. It is sectional drawing in the 5-5 line in FIG. It is sectional drawing explaining the influence of static electricity about the conventional liquid crystal display device of a FFS mode. It is sectional drawing explaining the influence of static electricity about the conventional liquid crystal display device of a FFS mode.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Liquid crystal display device, 100 1st board | substrate, 104,106 circuit wiring, 116 common electrode, 118 pixel electrode, 140 wiring for predetermined electric potential connection, 200 2nd board | substrate, 208 translucent conductive film, 208a main body part, 208b drawer | drawing-out part 302 liquid crystal.

Claims (4)

A liquid crystal display device in which a pixel electrode and a common electrode for driving a liquid crystal sandwiched between a first substrate and a second substrate facing each other are provided on the first substrate,
The first substrate includes a circuit wiring disposed outside a pixel region in which a plurality of pixels including the pixel electrode and the common electrode are disposed , a peripheral circuit, and a wiring for a predetermined potential to which a predetermined potential is applied,
The second substrate includes a translucent conductive film disposed on the opposite side of the liquid crystal to face the pixel electrode and the common electrode and held at the predetermined potential,
The transparent conductive film has a lead portion which extends toward the outer edge and the predetermined potential wirings than the circuit wiring and the peripheral circuit positioned on the center side of the second substrate, through the lead portion Connected to the predetermined potential wiring;
The lead-out portion is formed only on one side of the second substrate,
The liquid crystal display device according to claim 1, wherein the predetermined potential wiring is formed on only the one side of the first substrate so as not to overlap the circuit wiring . The liquid crystal display device according to claim 1,
The liquid crystal display device, wherein the circuit wiring is a power supply wiring. The liquid crystal display device according to claim 1,
The liquid crystal display device, wherein the circuit wiring is a circuit wiring along an outer edge of the first substrate. The liquid crystal display device according to claim 1 ,
The liquid crystal display device, wherein the predetermined potential wiring is located on the outermost side of a terminal portion on one side of the first substrate.

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