Patent Publication Number: US-2016246121-A1

Title: Liquid crystal display panel and manufacturing method thereof, array substrate

Description:
TECHNICAL FIELD 
     The present invention relates to the field of liquid crystal display, especially relates to the field of liquid crystal display based on transverse electric field mode, and particularly to a liquid crystal display panel and an array substrate thereof, and a manufacturing method of liquid crystal display panel. 
     DESCRIPTION OF RELATED ART 
     Different from liquid crystal display panels based on longitudinal electric field modes such as twisted nematic (TN) mode and multi-domain vertical alignment (MVA) mode, a liquid crystal display panel based on transverse electric field mode such as in-plane switching (IPS) mode forms electrodes on only one substrate. 
     For example, as to a fringe field switching (FFS) mode liquid crystal display panel derived from the IPS mode, an electrode layer is spacedly arranged below a pixel electrode, when a driving voltage is applied, a fringe electric field is generated to make liquid crystal molecules to be deflected at the surface of the electrode layer, the transmittance of backlight is increased and a large viewing angle display is achieved. However, when the driving voltage is applied, parasitic capacitances are inevitably formed between the pixel electrode and the underlying electrode layer spaced therefrom, if the parasitic capacitances are excessively large, a charging ratio of pixel unit of the liquid crystal display panel would be influenced and thereby the display effect and quality of the liquid crystal display panel would be dramatically degraded. 
     Currently, the parasitic capacitances generally are reduced in the industry by increasing a thickness of an insulating layer between the pixel electrode and the underlying electrode layer. However, the increase of thickness of the insulating layer would inevitably leads to an increase of driving voltage. The increase of driving voltage would inevitably leads to an increase of power consumption of driving circuit, and thereby the work hour of a display terminal using such liquid crystal display panel would be reduced. 
     SUMMARY 
     Accordingly, technical problems to be solved by embodiments of the present invention are to provide a liquid crystal display panel, a manufacturing method thereof and an array substrate, which can reduce the driving voltage, reduce the power consumption and increase the work hour of a display terminal using the liquid crystal display panel. 
     In order to solve the above technical problems, a technical solution proposed by the present invention is to provide a liquid crystal display panel having oppositely and spacedly arranged first substrate and second substrate and multiple pixel units. Each of the pixel units includes a liquid crystal layer interposed between the first substrate and the second substrate, and a first electrode layer, a second electrode layer and an insulating layer arranged on a side of the first substrate facing toward the liquid crystal layer. The first electrode layer is arranged neighboring with the first substrate. The insulating layer is interposed between the first electrode and the second electrode layer. The second electrode layer is formed with an electrode pattern. The insulating layer is formed with a groove corresponding to a region without the electrode pattern of the second electrode layer. 
     In an exemplary embodiment, the electrode pattern is multiple spaced strip structures, and a region of the insulating layer between neighboring two of the strip structures is formed with the groove. 
     In an exemplary embodiment, a depth of the groove is 0˜6000 angstroms. 
     In an exemplary embodiment, the first electrode layer includes a common electrode, the second electrode layer includes a pixel electrode, and the electrode pattern includes a pixel electrode pattern. 
     In order to solve the above technical problems, still another technical solution of the present invention is to provide a manufacturing method of a liquid crystal display panel. The manufacturing method includes: coating a photoresist layer on a base sequentially deposited with a first electrode layer, an insulating layer and a second electrode layer; performing a first etching on a region of the second electrode layer uncovered by the photoresist layer to thereby form an electrode pattern on the second electrode layer and surface expose a region of the insulating layer uncovered by the photoresist layer; performing a second etching on the surface-exposed region of the insulating layer to thereby form a groove in the insulating layer corresponding to a region without the electrode pattern of the second electrode layer; and removing the photoresist layer. 
     In an exemplary embodiment, the first etching is a wet-type etching, and the second etching is a dry-type etching. 
     In an exemplary embodiment, the formed electrode pattern is multiple spaced strip structures, and a region of the insulating layer between neighboring two of the strip structures is formed with the groove. 
     In an exemplary embodiment, a depth of the formed groove is 0˜6000 angstroms. 
     In an exemplary embodiment, the first electrode layer includes a common electrode, the second electrode layer includes a pixel electrode, and the electrode pattern includes a pixel electrode pattern. 
     In order to solve the above technical problems, even still another technical solution proposed by the present invention is to provide an array substrate suitable for a liquid crystal display panel having a liquid crystal layer and multiple pixel units. The array substrate includes: a base, a first electrode layer, a second electrode layer and an insulating layer arranged on a side of the base facing toward the liquid crystal layer. The first electrode layer is arranged neighboring with the base. The insulating layer is interposed between the first electrode layer and the second electrode layer. The second electrode layer is formed with an electrode pattern. The insulating layer is formed with a groove corresponding to a region without the electrode pattern of the second electrode layer. 
     In an exemplary embodiment, the electrode pattern is multiple spaced strip structures, and a region of the insulating layer between neighboring two of the strip structures is formed with the groove. A depth of the groove is 0˜6000 angstroms. 
     In an exemplary embodiment, the first electrode layer includes a common electrode, a second electrode layer includes a pixel electrode, and the electrode pattern includes a pixel electrode pattern. 
     By the above technical solutions, beneficial effects can be achieve by the present invention are that: by forming a groove in the insulating layer interposed between the first electrode layer and the second electrode layer, and the groove is corresponding to a region without the electrode pattern of the second electrode layer, which not only can reduce the parasitic capacitances formed by the first electrode layer and the second electrode layer being applied with a driving voltage, but also is without increasing the thickness of the insulating layer. Compared with the prior art, the driving voltage is reduced, the power is saved and the work hour of a display terminal using the liquid crystal display panel is increased. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic structural cross-sectional view of a liquid crystal display panel according to a preferred embodiment of the present invention. 
         FIG. 2  is a schematic structural cross-sectional view of a pixel unit according to a preferred embodiment of the present invention. 
         FIG. 3  is a schematic view of transmittance of a pixel unit without groove in the prior art when a driving voltage is applied thereto. 
         FIG. 4  is a schematic view of transmittance of a pixel unit according to a preferred embodiment of the present invention when a driving voltage is applied thereto. 
         FIG. 5  is a schematic view of transmittance of a pixel unit without groove in the prior art when another driving voltage is applied thereto. 
         FIG. 6  is a schematic view of transmittance of a pixel unit according to a preferred embodiment of the present invention when another driving voltage is applied thereto. 
         FIG. 7  is a schematic view of relationships between azimuth angles and vertical locations when a same driving voltage is applied to the pixel units of  FIGS. 5 and 6 . 
         FIG. 8  is a schematic view of relationships between transmittances and driving voltages applied to pixel units with grooves of different depths according to a preferred embodiment of the present invention. 
         FIG. 9  is a flowchart of a manufacturing method of a liquid crystal display panel according to a preferred embodiment of the present invention. 
         FIG. 10  is a schematic view of a first electrode layer, an insulating layer and a second electrode layer deposited on a base in the manufacturing method of a liquid crystal display panel according to the present invention. 
         FIG. 11  is a schematic view of a photoresist layer coated on the second electrode layer in the manufacturing method of a liquid crystal display panel according to the present invention. 
         FIG. 12  is a schematic view of the photoresist layer being exposed in the manufacturing method of a liquid crystal display panel according to the present invention. 
         FIG. 13  is a schematic view of the second electrode layer being performed with a first etching in the manufacturing method of a liquid crystal display panel according to the present invention. 
         FIG. 14  is a schematic view of the insulating layer is performed with a second etching in the manufacturing method of a liquid crystal display panel according to the present invention. 
         FIG. 15  is a schematic view of the photoresist layer being removed in the manufacturing method of a liquid crystal display panel according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     In the following, with reference to accompanying drawings of embodiments of the present invention, technical solutions in the embodiments of the present invention will be clearly and completely described. Apparently, the embodiments of the present invention described below only are a part of embodiments of the present invention, but not all embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary skill in the art without creative effort belong to the scope of protection of the present invention. 
       FIG. 1  is a schematic structural cross-sectional view of a liquid crystal display panel according to a preferred embodiment of the present invention. As shown  FIG. 1 , the liquid crystal display panel  10  in the embodiment includes a first substrate  11 , a second substrate  12 , a liquid crystal layer  13  and multiple pixel units (not shown). 
     The first substrate  11  and the second substrate  12  are oppositely and spacedly arranged. The first substrate  11  is a TFT (thin film transistor) array substrate. The first substrate  11  includes a transparent base, and various wirings, pixel electrodes and so on formed on the transparent base. The second substrate  12  is a CF (color filter) substrate. 
     The liquid crystal layer  13  is sandwiched between the first substrate  11  and the second substrate  12 . In the embodiment, preferably, the liquid crystal layer  13  includes liquid crystal molecules  131  with negative dielectric anisotropy and multiple reactive monomers  132  mixed into the liquid crystal molecules  131 . The liquid crystal molecules  131  are a liquid crystal material with characteristic of deflection and orientation in a specific direction when a driving voltage is applied, and by use of thresholds of applied driving voltage, different deflections and orientations can be achieved. The reactive monomers  132  each are a polymerizable monomer, such as acrylic resin monomer molecule, methyl acrylate resin monomer molecule, vinyl resin monomer molecule, ethylene oxide resin monomer molecule, epoxy resin monomer molecule, or any combination thereof. 
       FIG. 2  is a schematic structural cross-sectional view of a pixel unit according to a preferred embodiment of the present invention. Since each of pixel units of the liquid crystal display panel  10  includes R, G, B three pixels, and the pixel units have similar structures, and thus only one pixel unit  20  being taken as an example for the purpose of illustration will be described below. 
     Referring to  FIG. 1  and  FIG. 2  together, the pixel unit  20  in the embodiment includes the liquid crystal layer  13  of a corresponding region, and a first electrode layer  21 , a second electrode layer  22  and an insulating layer  23  all formed on a side of the first substrate  11  facing toward the liquid crystal layer  13 . 
     The first electrode layer  21  is arranged neighboring with the first substrate  11 . The insulating layer  23  is interposed between the first electrode layer  21  and the second electrode layer  22 , and thereby the first electrode layer  21  and the second electrode layer  22  are oppositely and spacedly arranged. The second electrode layer  22  is arranged neighboring with the liquid crystal layer  13 . 
     The second electrode layer  22  in the embodiment is formed with a (pixel) electrode pattern, i.e., is a patterned electrode layer. The insulating layer  23  is formed with grooves  221   a,    221   b,    221   c,    221   d  corresponding to regions without the electrode pattern of the second electrode layer  22 . In particular, preferably, the electrode pattern includes multiple spaced strip structures  222   a,    222   b,    222   c,    222   d,    222   e.  Each of the grooves is disposed between neighboring two strip structures, i.e., as shown in  FIG. 2 , the groove  221   a  is disposed between the strip structure  222   a  and the strip structure  222   b,  the groove  221   b  is disposed between the strip structure  222   b  and the strip structure  222   c,  the groove  221   c  is disposed between the strip structure  222   c  and the strip structure  222   d,  and the groove  221   d  is disposed between the strip structure  222   d  and the strip structure  222   e.    
     In the embodiment, the pixel unit  20  corresponds to a display region of the liquid crystal display panel  10 , and correspondingly the first electrode layer  21  is a common electrode, the second electrode layer  22  is a pixel electrode and the electrode pattern formed thereon is a pixel electrode pattern. As seen from FIG. 2 , the first electrode layer  21  is a continuous electrode layer, and the second electrode layer  22  is a patterned electrode layer. Moreover, the first electrode layer  21  and the second electrode layer  22  both are transparent electrode layers, manufacturing materials thereof may be the same or different and may be indium tin oxide (ITO), indium zinc oxide (IZO), other transparent and electrically conductive material, or any combination thereof. 
     When a driving voltage is connected and applied to a side of the first substrate  11 , the first electrode layer  21  and the second electrode layer  22  have parasitic capacitances C formed therebetween, i.e., the pixel electrode pattern and the first electrode layer  21  have multiple parasitic capacitances C formed therebetween. Moreover, the driving voltage makes a deflection electric field or alignment electric field for the liquid crystal layer  13  to be formed between the electrode pattern (strip structures  222   a,    222   b,    222   c,    222   d,    222   e ) of the second electrode layer  22  and the first electrode layer  21 . 
     When the alignment electric field is formed, preferably, the first substrate  11  and the second substrate  12  are illuminated by a light source with ultraviolet light wave range, so that the reactive monomers  132  can be fell into place according to the electric field caused by the driving voltage and thereby achieving the alignment and deflection of the liquid crystal molecules  131  in the liquid crystal display panel  10 . In particular, when the driving voltage is applied cooperative with the illumination of light in ultraviolet light wave range, the reactive monomers  132  occur polymerization to form a polymer for aligning the liquid crystal molecules  131  and thereby the liquid crystal molecules  131  are formed with a pre-tilt angle of 85˜95 degrees with respect to the first substrate  11 . 
     When the deflection electric field is formed, since potions of the insulating layer  23  corresponding to the grooves  221   a,    221   b,    221   c,    221   d  have a smaller thickness, the deflection electric field caused by the driving voltage has a large electric field intensity component on the z-axis direction in a three-dimensional coordinate system. Therefore, a torsion force for the liquid crystal molecules  131  can be significantly enhanced and the deflection angle of the liquid crystal molecules  131  is increased. That is, an azimuth angle of the pixel unit  20  is increased, a wide viewing angle thus can be achieved, the transmittance of backlight light can be improved and the aperture ratio of the liquid crystal display panel  10  can be increased. In addition, compared with the prior art, the display brightness of the pixel unit  20  is increased under the circumstance of a same driving voltage is applied. In other words, when same display brightnesses are reached, the applied driving voltage in the present embodiment as required is smaller, so that the power can be saved and the work hour of a display terminal using the liquid crystal display panel  10  can be increased. 
     In the embodiment, preferably, a depth of each of the grooves  221   a,    221   b,    221   c,    221   d  is the range of 0˜6000 angstroms (Å) but not equal to 0, i.e., greater than 0 and smaller than or equal to 6000 angstroms. In addition, the depths of the grooves  221   a,    221   b,    221   c,    221   d  may be the same or different from one another. As seen from  FIG. 2 , the grooves  221   a,    221   b,    221   c,    221   d  do not penetrate through the insulating layer  23 . In the following, with reference to  FIGS. 3 through 8 , a situation of the grooves  221   a,    221   b,    221   c,    221   d  each having a depth of 6000 angstroms and another situation of without groove (i.e., the depth of groove is 0) will be described as comparison. 
     Referring to  FIGS. 3 and 4 , when same driving voltages of 2.0 volts are applied, straight-line distances between peaks and troughs of curves L 1 , L 2  with respect to the second electrode layer  22  represent corresponding transmittances, it is found that the transmittance L 2  corresponding to the pixel unit  20  with the grooves  221   a,    221   b,    221   c,    221   d  each having the depth of 6000 angstroms is larger than the transmittance L 1  corresponding to a pixel unit with groove of 0 angstrom depth. 
     Likewise, referring to  FIGS. 5 and 6 , when same driving voltages of 3.0 volts are applied, straight-line distances between peaks and troughs of curves L 3 , L 4  with respect to the second electrode layer  22  represent corresponding transmittances, it is found that the transmittance L 4  corresponding to the pixel unit  20  with the grooves  221   a,    221   b,    221   c,    221   d  each having the depth of 6000 angstroms is larger than the transmittance L 2  corresponding to a pixel unit with groove of 0 angstrom depth. 
     Referring to  FIGS. 4 and 6 , when the depths of the grooves  221   a,    221   b,    221   c,    221   d  are fixed to be 6000 angstroms, the transmittance L 4  corresponding to the applied driving voltage of 3.0 volts is larger than the transmittance L 2  corresponding to the applied driving voltage of 2.0 volts. 
     Likewise, referring to  FIGS. 3 and 5 , when the depth of groove is fixed to be 0, the transmittance L 3  corresponding to the applied driving voltage of 3.0 volts is larger than the transmittance L 1  corresponding to the applied driving voltage of 2.0 volts. 
     In addition, referring to  FIGS. 5, 6 and 7 , when the same driving voltages of 3.0 volts are applied, curves A 1 , B 1 , C 1  represent relationships between vertical locations and azimuth angles corresponding to the pixel unit with groove of 0 angstrom depth, curves A 2 , B 2 , C 2  represent relationships between vertical locations and azimuth angles corresponding to the pixel unit  20  with grooves each having a depth of 6000 angstroms. It is found that, when the same driving voltages are applied, compared with the pixel unit of prior art, the azimuth angle of the liquid crystal molecules  131  of the pixel unit  20  in the embodiment is increased, the increase of azimuth angle leads to the improvement of brightness of the pixel unit  20 . That is, if same brightnesses are achieved, the applied driving voltage required by the pixel unit  20  in the embodiment is smaller. 
     Furthermore, referring to  FIG. 8 , the curve V 1  represents a relationship between transmittance and an applied driving voltage when the depth of groove is 0, the curve V 2  represents a relationship between transmittance and an applied driving voltage when the depths of the grooves  221   a,    221   b,    221   c,    221   d  all are 2000 angstroms, the curve V 3  represents a relationship between transmittance and an applied driving voltage when the depths of the grooves  221   a,    221   b,    221   c,    221   d  all are 4000 angstroms, and the curve V 4  represents a relationship between transmittance and an applied driving voltage when the depths of the grooves  221   a,    221   b,    221   c,    221   d  all are 6000 angstroms. It can be found that with the increase of the depths of the grooves  221   a,    221   b,    221   c,    221   d,  a starting voltage Vth and an operating voltage Vmax corresponding to a maximum brightnesses during the liquid crystal layer  13  is driven are decreased. For example, when the depths of the grooves  221   a,    221   b,    221   c,    221   d  all are 0 angstrom, the staring voltage Vth is 1.8 volts and the operating voltage Vmax is 5.5 volts; when the depths of the grooves  221   a,    221   b,    221   c,    221   d  are 2000 angstroms, the starting volt Vth is 1.5 volts and the operating voltage Vmax is 5 volts; when the depths of the grooves  221   a,    221   b,    221   c,    221   d  are 4000 angstroms, the starting volt Vth is 1.4 volts and the operating voltage Vmax is 4.5 volts; and the depths of the grooves  221   a,    221   b,    221   c,    221   d  are 6000 angstroms, the starting volt Vth is 1.3 volts and the operating voltage Vmax is 4.25 volts. That is, when the depths of the grooves  221   a,    221   b,    221   c,    221   d  are increased from 0 angstrom to 6000 angstroms, the starting voltage Vth is decreased from 1.8 volts to 1.3 volts, and the operating voltage Vmax is decreased from 5.5 volts to 4.25 volts. 
     As seen from  FIGS. 4 through 8  that, when same driving voltages are applied, the larger the depths of the grooves  221   a,    221   b,    221   c,    221   d,  the higher of the transmittance corresponding to the pixel unit  20 , and the higher of the display brightness of the liquid crystal display panel  10 . Moreover, when the depths of the grooves  221   a,    221   b,    221   c,    221   d  are fixed, the larger of the applied driving voltage, the higher of the transmittance corresponding to the pixel unit  20 , and the higher of the display brightness of the liquid crystal display panel  10 ; that is, when same brightnesses are achieved, the applied driving voltage required by the pixel unit  20  of the present embodiment is far less than the applied driving voltage required by the pixel unit of prior art, and therefore it can reduce the power consumption compared with the prior art, the work hour of display terminal using the liquid crystal display panel  10  can be increased, the parasitic capacitances C formed by the first electrode layer  21  and the second electrode layer  22  being applied with a driving voltage can be reduced, and the thickness of the insulating layer  23  is without increase compared with the prior art. 
       FIG. 9  is a flowchart of a manufacturing method of a liquid crystal display panel according to a preferred embodiment of the present invention. As shown in  FIG. 9 , the manufacturing method of a liquid crystal display panel in the embodiment includes the following steps: 
     Step S 101 : sequentially depositing a first electrode layer, an insulating layer and a second electrode layer on a base. 
     As shown in  FIG. 10 , the base  111  may be glass base, plastic base or flexible base. The first electrode layer  112  is an indium tin oxide glass layer or silicon oxide, nitride oxide or a combination thereof. The insulating layer  113  may be made of a dielectric material such as nitride oxide layer, silicon oxide layer or silicon oxynitride, and formed by chemical vapor deposition or other thin film deposition techniques. The second electrode layer  114  may have a material same as or different from that of the first electrode layer  112 . 
     Step  102 , coating a photoresist layer on the base sequentially deposited with the first electrode layer, the insulating layer and the second electrode layer. 
     The photoresist layer  115  is coated on the second electrode layer  114 . As shown in  FIGS. 11 and 12 , the photoresist layer  115  is performed with a first photo masking process by employing an exposure technique based on a mask (i.e., commonly known as photomask) to thereby form exposed portions D and unexposed portions E required by the photo masking process. The exposed portions D correspond to grooves will be formed, and the unexposed portions E correspond to an electrode pattern will be formed, i.e., multiple spaced strip structures. 
     Step  103 : performing a first etching on regions of the second electrode layer uncovered by the photoresist layer to thereby form the electrode pattern on the second electrode layer and surface expose regions of the insulating layer uncovered by the photoresist layer. 
     As shown in  FIG. 13 , the photoresist layer  115  is used as an etching mask, the first etching performed on the regions of the second electrode layer  114  uncovered by the photoresist layer  115  is a wet-type etching. Since the electrode pattern will be formed includes multiple spaced strip structures, the regions of the insulating layer  113  uncovered by the photoresist  115  (corresponding to the exposed portions D) will be surface-exposed after the first etching. 
     Step  104 , performing a second etching on the surface-exposed regions of the insulating layer to thereby form grooves in the insulating layer corresponding to regions without the electrode pattern of the second electrode layer. 
     As shown in  FIG. 14 , the photoresist layer  115  is used as an etching mask, the second etching performed on the surface-exposed regions (corresponding to the exposed portions D) of the insulating layer  112  uncovered by the photoresist layer  115  is a dry-type etching. Moreover, the regions corresponding to the exposed portions D are formed with multiple grooves  116 , and the grooves  116  do not penetrate through the insulating layer  113 . The grooves  116  each have a depth in the range of 0˜6000 angstroms but not equal to 0 angstrom, i.e., greater than 0 angstrom and smaller than or equal to 6000 angstroms. In addition, the depths of the grooves  116  may be the same or different from one another. 
     Step S 105 , removing the photoresist layer. 
     As shown in  FIG. 15 , a common photo masking process is used to completely expose the remaining photoresist layer  115  (corresponding to the unexposed portions E), and thereby the photoresist layer  115  is removed. 
     Regarding the array substrate obtained by the manufacturing method of a liquid crystal display panel of the present embodiment, a pixel unit thereof has a structure same as that of the pixel unit  20  according to the embodiment illustrated in  FIG. 2 , and thus can achieve the same technical effect. 
     In summary, in the embodiments of the present invention, the insulating layer interposed between the first electrode layer and the second electrode layer is formed with grooves, and the grooves correspond to the regions without the electrode pattern of the second electrode layer, which not only can decrease the parasitic capacitances formed by the first electrode layer and the second electrode layer being applied with a driving voltage, but also is without increasing the thickness of the insulating layer compared with the prior art. Accordingly, compared with the prior art, the driving voltage can be decreased, the power can be saved, and the work hour of a display terminal using the liquid crystal display panel can be increased consequently. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.