JP2007147793A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wide visual field angle and to obtain desired voltage-luminance characteristics in a liquid crystal display device driven in a VA system. <P>SOLUTION: In the liquid crystal display device having a liquid crystal display panel wherein a liquid crystal material is interposed between a first substrate wherein a plurality of gate lines and a plurality of drain lines are disposed in a matrix shape and which has pixel electrodes each positioned in each pixel region enclosed by the adjacent two gate lines and the adjacent two drain lines and a second substrate having a common electrode and liquid crystal molecules are aligned in a direction vertical to surfaces of respective substrate when potential difference between the pixel electrodes and the common electrode is zero in the liquid crystal material, the first substrate has a first insulating layer superposed on the entire region of the pixel electrodes on the surface side of the pixel electrodes opposed to the common electrode and a second insulating layer embedded in the first insulating layer and having a superposed surface smaller than the surface of the pixel electrodes and dielectric constants of the first and the second insulating layers are different from each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a technique effective when applied to a liquid crystal display device driven by a VA (Vertical Alignment) method.

  Conventionally, there is a liquid crystal display device of a driving method called a VA method.

  In the liquid crystal display device driven by the VA method, a pixel electrode is disposed on one of a pair of substrates sandwiching a liquid crystal material, and a common electrode is disposed on the other substrate. Then, the orientation of liquid crystal molecules in the liquid crystal material is controlled by generating or extinguishing an electric field (lines of electric force) perpendicular to the substrate surface.

  In the case of a liquid crystal display device driven by the VA method, liquid crystal molecules in the liquid crystal material are aligned in a direction perpendicular to the substrate surface when the potential difference between the pixel electrode and the common electrode is zero. ing. When a voltage is applied to the pixel electrode, the pixel electrode is oriented at a predetermined angle with respect to the substrate surface in accordance with the absolute value of the potential difference between the pixel electrode and the common electrode.

  In the liquid crystal display device driven by the VA method, for example, when the potential difference between the pixel electrode and the common electrode is zero, that is, when the liquid crystal molecules are aligned in a direction perpendicular to the substrate surface. Black display is performed, and white display is performed when the liquid crystal molecules are aligned in a direction parallel to the substrate surface.

  In the liquid crystal display device driven by the VA method, in order to realize a wide viewing angle, for example, a display device in which one of the pixel electrode or the common electrode is formed on an insulating film having an uneven surface is proposed. (For example, see Patent Document 1).

In the liquid crystal display device described in Patent Document 1, for example, an insulating film provided on the liquid crystal layer side of an electrode having an inclined surface is used to flatten the surface in contact with the liquid crystal layer with respect to the substrate surface. A good black display is realized on the front surface (vertical direction) of the substrate when no voltage is applied.
Japanese Patent Laid-Open No. 2002-229029

  However, in the liquid crystal display device described in Patent Document 1, one of the pixel electrode and the common electrode is provided, for example, on an insulating film having an uneven surface. Therefore, an electrode formed on the uneven insulating film is likely to be disconnected or cracked due to the unevenness of the insulating film. As a result, the uneven shape of the insulating film has a low degree of design freedom, and it is difficult to obtain desired voltage-luminance characteristics.

  An object of the present invention is to provide a technique capable of realizing a wide viewing angle and obtaining a desired voltage-luminance characteristic in a liquid crystal display device driven by a VA method.

  Another object of the present invention is to provide a technique capable of preventing light leakage during black display and improving contrast in the liquid crystal display device.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  The outline of typical inventions among the inventions disclosed in the present application will be described as follows.

  (1) A plurality of gate lines and a plurality of drain lines are arranged in a matrix, and a pixel electrode is provided in a pixel region surrounded by two adjacent gate lines and two adjacent drain lines. A liquid crystal material is sandwiched between a first substrate and a second substrate having a common electrode, and the liquid crystal material contains liquid crystal molecules when the potential difference between the pixel electrode and the common electrode is zero. A liquid crystal display device having a liquid crystal display panel oriented in a direction perpendicular to each substrate surface, wherein the first substrate is formed on the surface of the pixel electrode facing the common electrode. A first insulating layer that overlaps with the entire region; and a second insulating layer that is embedded in the first insulating layer and has an overlapping area smaller than the area of the pixel electrode. Liquid crystal display in which the dielectric constant of the second insulating layer is different from that of the second insulating layer It is the location.

  (2) In the above (1), the first substrate includes two pixel electrodes having different distances from the common electrode in one pixel region, and the first substrate having a long distance from the common electrode. The pixel electrode is made of a conductive material that reflects light incident from the second substrate side and emits the light to the second substrate side, and the second pixel electrode that is close to the common electrode has the first electrode The first insulating layer and the second insulating layer are made of a conductive material that transmits light incident from the back side of the substrate and emits the light to the second substrate side, and the first insulating layer and the second insulating layer are the common electrode of the first pixel electrode. Is a liquid crystal display device that is provided on the side facing the surface.

  (3) In the above (2), a third insulating layer overlapping at least the entire area of the second pixel electrode on the surface of the second pixel electrode facing the common electrode, and the third pixel electrode A fourth insulating layer embedded in the insulating layer and having an overlapping area smaller than the area of the second pixel electrode, and a dielectric constant of the third insulating layer and the fourth insulating layer This is a liquid crystal display device having different dielectric constants.

  (4) In (3), the dielectric constant of the third insulating layer is equal to the dielectric constant of the first insulating layer, and the dielectric constant of the fourth insulating layer is equal to the dielectric constant of the second insulating layer. It is an equal liquid crystal display device.

  The liquid crystal display device of the present invention is embedded in the first insulating layer on the surface of the pixel electrode facing the common electrode, the first insulating layer overlapping the entire area of the pixel electrode, and the first insulating layer, A second insulating layer having an overlapping area smaller than the area of the pixel electrode. At this time, the second insulating layer is made of a material having a dielectric constant different from that of the first insulating layer. In this way, an oblique electric field is partially generated in the vicinity of the region where the second insulating layer is interposed. At this time, an electric field perpendicular to the substrate surface is generated at the end of the pixel electrode where the second insulating layer is not interposed. Therefore, the orientation of the liquid crystal molecules in the liquid crystal material interposed between the pixel electrode and the common electrode can be controlled, and a wide viewing angle can be realized.

  At this time, the alignment of the liquid crystal molecules, that is, the control of the electric field distribution is controlled by the shape (overlapping area) of the second insulating layer provided on the pixel electrode, the first insulating layer, and the second insulating layer. This can be realized by changing the combination of dielectric constants of the insulating layers. Therefore, the pixel electrode can be formed on a flat insulating layer. Therefore, for example, as compared with the display device described in Patent Document 1, the degree of freedom with respect to the electric field distribution is increased, and a desired voltage-luminance characteristic can be easily obtained.

  Further, by embedding the second insulating layer in the first insulating layer, the surface of the second insulating layer facing the common electrode (liquid crystal material) can be easily flattened. In other words, when the potential difference between the pixel electrode and the common electrode is zero, the liquid crystal molecules in the liquid crystal material can be aligned in the direction perpendicular to the substrate surface. Therefore, it is possible to prevent light leakage during black display and improve contrast.

  The above-described configuration can be applied to various configurations of liquid crystal display panels (liquid crystal display devices) that are driven by the VA method. In particular, the configuration is preferably applied to a transflective liquid crystal display panel. In the case of a transflective liquid crystal panel, in the reflective region where the first pixel electrode is arranged, a voltage drop occurs due to the arrangement of the first insulating layer and the second insulating layer, and the liquid crystal layer in the reflective region The applied electric field changes. That is, the potential difference between the first pixel electrode and the common electrode in the reflection region and the potential difference between the second pixel electrode and the common electrode in the transmission region where the second pixel electrode is disposed are fixed. The distribution of the electric field can be changed. For this reason, in the luminance-voltage characteristics of the reflective region and the transmissive region, the voltage at which the luminance is maximum can be matched.

  In the case of the transflective liquid crystal display panel, not limited to the above-described configuration, for example, a third insulating layer and a fourth insulating layer having a dielectric constant different from that of the third insulating layer are provided in the transmissive region. By arranging, the electric field distribution can be controlled in the same manner as the reflection region. Therefore, a wide viewing angle of the transmissive region can be realized.

  Further, when the third insulating layer and the fourth insulating layer are arranged in the transmission region, the relationship between the dielectric constants is the relationship between the dielectric constants of the first insulating layer and the second insulating layer in the reflection region. Can be set independently, but the dielectric constants of the third insulating layer and the first insulating layer can be made equal, and the dielectric constants of the fourth insulating layer and the second insulating layer can be made equal. preferable. In this case, the third insulating layer can be made of the same material as that of the first insulating layer, and the fourth insulating layer can be made of the same material as that of the second insulating layer.

  The second insulating layer and the fourth insulating layer can have any shape as long as the overlapping area with the pixel electrode is smaller than the area of the pixel electrode, for example, a spherical insulating material such as a bead. The body may be buried. In particular, in a transflective liquid crystal display panel, if a spherical insulator is embedded as the second insulating layer, light incident from the second substrate side is transmitted between the first insulating layer and the second insulating layer. Scattering at the interface can reduce glare in the reflection region.

Hereinafter, the present invention will be described in detail together with embodiments (examples) with reference to the drawings.
In all the drawings for explaining the embodiments, parts having the same function are given the same reference numerals and their repeated explanation is omitted.

  1 and 2 are schematic views showing a schematic configuration of a liquid crystal display panel included in a liquid crystal display device to which the present invention is applied. FIG. 1 is a plan view of the liquid crystal display panel, and FIG. It is sectional drawing seen by the line.

  The liquid crystal display device of the present invention has, for example, a liquid crystal display panel in which a liquid crystal material 3 is sandwiched between a pair of substrates 1 and 2, as shown in FIGS. At this time, both the substrates 1 and 2 are bonded with an annular sealing material 4, and the liquid crystal material 3 is enclosed in a space surrounded by the both substrates 1 and 2 and the sealing material 3. At this time, although omitted in FIGS. 1 and 2, a plurality of gate lines and a plurality of drain lines are arranged in a matrix on one substrate (first substrate) 1 and adjacent to each other. A region surrounded by two drain lines adjacent to the two gate lines is a pixel region. A TFT element and a pixel electrode are disposed in each pixel region. The other substrate (second substrate) 2 is provided with a common electrode facing the pixel electrode, a color filter, and the like.

  Although not described in detail, the liquid crystal display device having the liquid crystal display panel as shown in FIGS. 1 and 2 includes, for example, a gate for inputting a scanning signal to the gate line in addition to the liquid crystal display panel. A TCP (Tape Carrier Package) on which a driver is mounted, a TCP on which a data driver for inputting a data signal to the drain line is mounted, and a circuit board such as a timing controller. Instead of TCP, COF (Chip On Film) may be used. In addition, when the liquid crystal display device is a transmissive type or a transflective type, a backlight unit is additionally provided.

  Hereinafter, the configuration of the pixel region when the present invention is applied to the liquid crystal display panel as shown in FIGS. 1 and 2 will be described.

  3 to 5 are schematic views showing a schematic configuration of the liquid crystal display panel according to the first embodiment of the present invention. FIG. 3 is a plan view showing a configuration example of one pixel region, and FIG. FIG. 5 is a cross-sectional view taken along the line CC ′ of FIG. 3. FIG. 3 is a plan view showing one pixel region of the first substrate on which the pixel electrode is arranged. FIGS. 4 and 5 are diagrams showing the first substrate and the first substrate viewed along the cutting lines, respectively. It is sectional drawing which shows the structure of the 2nd board | substrate which opposes.

  The liquid crystal display panel of Example 1 is a transmissive liquid crystal display panel. As shown in FIGS. 3 to 5, the first substrate 1 is a surface of the glass substrate 101 facing the second substrate 2. In addition, a gate line 102, a semiconductor layer 103, a drain line 104, a source electrode 105, a pixel electrode 106, and the like are provided. At this time, the gate line 102 is provided on the surface of the glass substrate 101, and the semiconductor layer 103, the drain line 104, and the source electrode 105 are provided above the gate line 102 through the first insulating layer 107. In addition, a pixel electrode 106 is provided above the semiconductor layer 103, the drain line 104, and the source electrode 105 with a second insulating layer 108 interposed therebetween. At this time, the pixel electrode 106 is electrically connected to the source electrode 105 through the through hole TH.

  A third insulating layer 109 is provided on the pixel electrode 106, that is, on the surface facing the second substrate 2. In addition, a fourth insulating layer 110 overlapping with the pixel electrode 106 is embedded in the third insulating layer 109. At this time, the fourth insulating layer 110 has an overlapping area with the pixel electrode 106 smaller than the area of the pixel electrode 106. The dielectric constant of the fourth insulating layer 110 is preferably larger than the dielectric constant of the third insulating layer 109, but may be smaller. That is, it is sufficient that the dielectric constants of the two insulating layers 109 and 110 are different.

  An alignment film 111 is provided on the third insulating layer 109.

  In the first substrate 1, retardation plates 112 a, 112 b, 112 c and a polarizing plate 113 are laminated on the back surface of the glass substrate 101 on which the gate line 102 and the like are provided.

  On the other hand, in the second substrate 2, a black matrix 202 that divides each pixel region is provided on the surface of the glass substrate 201 facing the first substrate 1, and a color is formed in a region facing each pixel electrode 106. A filter 203 is provided. A common electrode 205 is provided on the black matrix 202 and the color filter 203 with an overcoat layer 204 interposed therebetween. An alignment film 206 is provided on the common electrode 205.

  In the second substrate 2, retardation plates 207 a, 207 b, 207 c and a polarizing plate 208 are laminated on the back surface of the glass substrate 201 on which the common electrode 205 is provided.

  At this time, the liquid crystal material 3 sandwiched between the first substrate 1 and the second substrate 2 has liquid crystal molecules 301 as shown in FIG. 5 when the potential difference between the pixel electrode 106 and the common electrode 205 is zero. It is oriented in a direction perpendicular to the substrate surface.

  In manufacturing the first substrate 1 in the liquid crystal display panel according to the first embodiment, the process up to the step of forming the pixel electrode 106 may be performed by the same method as in the prior art, and thus detailed description thereof is omitted.

  Then, after forming up to the pixel electrode 106 by the same method as before, the fourth insulating layer 110 is formed. When forming the fourth insulating layer 110, first, for example, a CVD film of SiN (dielectric constant 6.7) is formed on the pixel electrode 106. At this time, the thickness of the CVD film is, for example, 500 nm. Then, a photosensitive resist is applied on the CVD film, exposed and developed. Then, the CVD film is etched using the developed resist as a mask to form the fourth insulating layer 110, and then the resist is removed.

  After the fourth insulating layer 110 is formed, a third insulating layer 109 is formed next. When forming the third insulating layer 109, first, for example, a photosensitive resin having a dielectric constant of about 3.3 is applied so as to cover the pixel electrode 106 and the fourth insulating layer 110. Then, the photosensitive resin is exposed to light, developed and partially removed, and then baked. When baking the said photosensitive resin, the unevenness | corrugation of the surface after baking can be controlled by changing baking conditions, such as temperature and time. In the first embodiment, for example, baking is performed at 230 ° C. for 60 minutes so that the surface becomes flat. Further, when the photosensitive resin is applied, for example, the photosensitive resin is applied so as to have a thickness of about 1.5 μm after baking.

  After the third insulating layer 110 and the third insulating layer 109 are formed on the pixel electrode 106 by the procedure as described above, the alignment film 111 is formed by the same method as before.

  Moreover, when manufacturing the 2nd board | substrate 2, since it should just carry out by the same method as the past, detailed description is abbreviate | omitted.

  And when manufacturing a liquid crystal display panel using the 1st board | substrate 1 and the 2nd board | substrate 2, the cyclic | annular sealing material 4 is first apply | coated on the 1st board | substrate 1, for example. For example, after the liquid crystal material 3 is dropped in the region surrounded by the sealing material 4, the second substrate 2 is overlaid, and the first substrate 1 and the second substrate 2 are bonded together by the sealing material 4. The liquid crystal material 3 is encapsulated. Alternatively, the sealing material 4 is formed in a ring shape with a part missing, and after the first substrate 1 and the second substrate 2 are bonded, the liquid crystal material 3 is injected from the part in which the sealing material 4 is missing, You may seal with an epoxy resin etc. The liquid crystal material 3 is, for example, a negative liquid crystal with Δn = 0.10. At this time, the liquid crystal molecules 301 are aligned perpendicular to the substrate plane by the alignment regulating force of the alignment films 111 and 206.

  After the liquid crystal material 3 is sealed between the first substrate 1 and the second substrate 2, the retardation plates 112a, 112b, 112c and the polarizing plate 113 are bonded to the first substrate 1, and the second substrate The retardation plates 207a, 207b, 207c and the polarizing plate 208 are bonded to the substrate 2.

  At this time, the phase difference plates 112a, 112b, and 112c of the first substrate 1 are respectively, for example, a Z-axis phase difference plate (Δn · d = 110 nm (when tilted at 45 degrees with respect to the main surface of the substrate)) 112a, Δn · d = 140 nm uniaxially stretched phase difference plate (λ / 4 phase difference plate) 112 b at which the phase axis angle is 175 °, Δn · d = 270 nm uniaxially stretched phase difference at which the slow axis angle is 55 ° A plate (λ / 2 phase difference plate) 112c is bonded. The polarizing plate 113 of the first substrate 1 is bonded so that the transmission axis angle is 160 degrees. At this time, the retardation plates 207a, 207b, and 207c of the second substrate 2 are, for example, Z-axis retardation plates (Δn · d = 110 nm (when inclined by 45 degrees with respect to the main surface of the substrate)) 207a, Δn · d = 140 nm uniaxially stretched phase difference plate (λ / 4 phase difference plate) 207b with a slow axis angle of 85 °, Δn · d = 270 nm uniaxially stretched with a slow axis angle of 145 ° A phase difference plate (λ / 2 phase difference plate) 207c is bonded. The polarizing plate 208 of the second substrate 2 is bonded so that the transmission axis angle is 70 degrees.

  The slow axis and the transmission axis are shown as angles measured counterclockwise with reference to a predetermined direction (for example, the horizontal direction of the screen).

  The Z-axis phase difference plates 112a and 207a may not be provided, but are preferably provided for wide viewing angle.

  6 and 7 are schematic diagrams for explaining the operation and effect of the display panel according to the first embodiment. FIG. 6 shows the distribution of equipotential lines when there is a potential difference between the pixel electrode and the common electrode. FIG. 7 is a sectional view showing the alignment of liquid crystal molecules when there is a potential difference between the pixel electrode and the common electrode. 6 and 7 are cross-sectional views showing only one pixel region in the cross-sectional view shown in FIG.

  In the liquid crystal display panel of the first embodiment, when black is displayed, that is, when the potential difference between the pixel electrode 106 and the common electrode 205 is zero, as shown in FIG. It is arranged. When a data signal is applied to the pixel electrode 106 and a potential difference is generated between the pixel electrode 106 and the common electrode 205, the liquid crystal molecules 301 are tilted in a direction parallel to the substrate surface according to the potential difference, thereby causing a potential difference. The corresponding gradation (luminance) is displayed.

  At this time, when the third insulating layer 109 and the fourth insulating layer 110 are provided over the pixel electrode 106, when a potential difference is generated between the pixel electrode 106 and the common electrode 205, as shown in FIG. The distribution of the equipotential surface ES changes in the region where the four insulating layers 110 overlap. At this time, when the dielectric constant of the fourth insulating layer 110 is larger than the dielectric constant of the third insulating layer 109, the electric field in the region where the fourth insulating layer 110 overlaps is greater than the region where the fourth insulating layer 110 does not overlap. However, the electric field becomes large. Therefore, the electric field generated between the pixel electrode 106 and the common electrode 205 is as shown in FIG. 7, and an oblique electric field (lines of electric force) EF is formed near the boundary between the third insulator 109 and the fourth insulator 110. Arise. As a result, for example, as shown in FIG. 7, the orientation of the liquid crystal molecules 301 can be changed between a region where the fourth insulating layer 110 overlaps and a region where the fourth insulating layer 110 does not overlap. Can be

  When the potential difference between the pixel electrode 106 and the common electrode 205 is zero, the liquid crystal molecules 301 are aligned perpendicular to the substrate plane, and therefore Δn · d = 0 in the liquid crystal material. Further, since the phase difference plates 112a, 112b, 112c of the first substrate 1 and the phase difference plates 207a, 207b, 207c of the second substrate 2 are arranged to cancel each other, Δn · d = 0. Therefore, when the potential difference between the pixel electrode 106 and the common electrode 205 is zero, black display is obtained by the arrangement (crossed Nicols) of the polarizing plate 113 of the first substrate 1 and the polarizing plate 208 of the second substrate 2.

  In Example 1, as shown in FIG. 5 and the like, the surface of the third insulating layer 109 on the pixel electrode 106 is flat. Therefore, light leakage at the edge portion of the orientation control protrusion seen during black display can be prevented, and the luminance during black display can be lowered. As a result, contrast can be improved.

  As described above, according to the liquid crystal display panel of Example 1, by providing the third insulating layer 109 and the fourth insulating layer 110 on the pixel electrode 106, the orientation of the liquid crystal molecules 301 in the liquid crystal material 3 is adjusted. It can be controlled and the display device can have a wide viewing angle.

  In addition, since the orientation of the liquid crystal molecules 301 is controlled by the thickness of the third insulating layer 109 and the shape (overlapping area) of the fourth insulating layer 110, the pixel electrode 106 may be flat and can easily achieve desired luminance-voltage characteristics. Can be realized.

  Further, since the surface of the third insulating layer 109 on the pixel electrode 106 can be easily flattened, high contrast can be easily achieved.

  In the first embodiment, for example, the fourth insulating layer 110 is formed by etching a CVD film of SiN. However, the fourth insulating layer 110 is not limited to this, and may be formed by various methods and materials. it can. In addition, the shape of the fourth insulating layer 110 is not limited to the shape shown in FIGS. 3 and 5 and may be other shapes.

  8 to 10 are schematic views showing a schematic configuration of the display panel according to the second embodiment of the present invention. FIG. 8 is a plan view showing a configuration example of one pixel region, and FIG. 9 is a DD of FIG. FIG. 10 is a cross-sectional view taken along the line EE ′ of FIG. 8. FIG. 8 is a plan view showing one pixel region of the first substrate on which the pixel electrode is arranged. FIGS. 9 and 10 are diagrams showing the first substrate and the first substrate viewed along the cutting lines, respectively. It is sectional drawing which shows the structure of the 2nd board | substrate which opposes.

  The liquid crystal display panel of Example 2 is a transflective liquid crystal display panel, and two pixel electrodes are arranged in one pixel region. In such a display panel, as shown in FIGS. 8 to 9, the first substrate 1 includes a gate line 102, a semiconductor layer 103, and a drain line on the surface side of the glass substrate 101 facing the second substrate 2. 104, a source electrode 105, a first pixel electrode 106a, a second pixel electrode 106b, and the like are provided.

  At this time, the gate line 102 is provided on the surface of the glass substrate 101, and the semiconductor layer 103, the drain line 104, and the source electrode 105 are provided above the gate line 102 through the first insulating layer 107. A first pixel electrode 106 a is provided above the semiconductor layer 103, the drain line 104, and the source electrode 105 with a second insulating layer 108 interposed therebetween. A second pixel electrode 106b is provided over the first pixel electrode 106a with a third insulating layer 110 interposed therebetween. At this time, the second pixel electrode 106b is provided so as not to overlap with the first pixel electrode 106a. The second pixel electrode 106b is provided with an opening 114 for controlling the alignment of liquid crystal molecules on the second pixel electrode 106b. At this time, the first pixel electrode 106a and the second pixel electrode 106b are electrically connected to the source electrode 105 through the through hole TH.

  An alignment film 111 is provided over the third insulating layer 109 and the second pixel electrode 106b.

  In the second embodiment, the fourth insulating layer 110 embedded in the third insulating layer 109 is provided on the first pixel electrode 106a. At this time, the fourth insulating layer 110 has an overlapping area with the first pixel electrode 106 a smaller than the area of the pixel electrode 106. Further, the dielectric constant of the fourth insulating layer 110 is different from the dielectric constant of the third insulating layer 109.

  In the first substrate 1, retardation plates 112 a, 112 b, 112 c and a polarizing plate 113 are laminated on the back surface of the glass substrate 101 on which the gate line 102 and the like are provided.

  On the other hand, in the second substrate 2, a black matrix 202 that divides each pixel region is provided on the surface of the glass substrate 201 facing the first substrate 1, and a color is formed in a region facing each pixel electrode 106. A filter 203 is provided. A common electrode 205 is provided on the black matrix 202 and the color filter 203 with an overcoat layer 204 interposed therebetween. An alignment film 206 is provided on the common electrode 205.

  In the second substrate 2, retardation plates 207 a, 207 b, 207 c and a polarizing plate 208 are laminated on the back surface of the glass substrate 201 on which the common electrode 205 is provided.

  At this time, the liquid crystal material 3 sandwiched between the first substrate 1 and the second substrate 2 has liquid crystal molecules 301 as shown in FIG. 9 when the potential difference between the pixel electrode 106 and the common electrode 205 is zero. It is oriented in a direction perpendicular to the substrate surface.

  FIG. 11 is a schematic cross-sectional view for explaining a reflective region and a transmissive region of the liquid crystal display panel according to the second embodiment.

  In the liquid crystal display panel according to the second embodiment, the first pixel electrode 106 a and the second pixel electrode 106 a having different distances from the common electrode 205 of the second substrate 2 are arranged on the first substrate 1, for example, as shown in FIG. A pixel electrode 106b is provided. Then, on the first pixel electrode 106 a, the third insulating layer 109 described in the first embodiment and the fourth insulating layer 110 embedded in the third insulating layer 109 are provided. At this time, as shown in FIG. 11, the first pixel electrode 106a is a reflective electrode that reflects the light LA incident from the second substrate 2 side and emits it to the second substrate 2 side. On the other hand, the second pixel electrode 106b transmits the light LB from the backlight unit 5 disposed behind the first substrate 1 and emits the light LB toward the second substrate 2 as shown in FIG. Type electrode. Hereinafter, the region where the first pixel electrode 106a is disposed is referred to as a reflective region, and the region where the second pixel electrode 106b is disposed is referred to as a transmissive region.

  In the liquid crystal display panel according to the second embodiment, when the first substrate 1 is manufactured, the process up to the step of forming the first pixel electrode 106a may be performed by the same method as in the prior art, and thus detailed description thereof is omitted.

  Note that the first pixel electrode 106a is an electrode formed in the reflective region. Therefore, the first pixel electrode 106a is formed using a metal material having a high reflectance such as Al / MoW, for example.

  Then, after forming the first pixel electrode 106a, the fourth insulating layer 110 and the third insulating layer 109 are formed according to the procedure described in the first embodiment.

  Then, after the fourth insulating layer 110 and the third insulating layer 109 are formed, the second pixel electrode 106b is formed next. When forming the second pixel electrode 106b, for example, after forming an ITO film on the third insulating layer 109, a photosensitive resist film is formed on the ITO film, and then exposed and developed. Then, the ITO film is etched using the developed resist as a mask to form the second pixel electrode 106b, and then the resist is removed.

  After the formation up to the second pixel electrode 106b by the procedure as described above, the alignment film 111 is formed by the same method as before.

  Moreover, when manufacturing the 2nd board | substrate 2, since it should just carry out by the same method as the past, detailed description is abbreviate | omitted.

  Further, when a liquid crystal display panel is manufactured using the first substrate 1 and the second substrate 2, the liquid crystal material 3 may be encapsulated by the method described in the first embodiment, and thus detailed description is omitted. To do.

  Also, the retardation plate 112a, 112b, 112c and the polarizing plate 113 are bonded to the first substrate 1 and the retardation plate 207a, 207b, 207c and the polarizing plate 208 are bonded to the second substrate 2, respectively. Since it may be bonded as described in Example 1, detailed description is omitted.

  12 and 13 are schematic diagrams for explaining the operation of the liquid crystal display panel according to the second embodiment. FIG. 12 is a diagram showing the alignment of liquid crystal molecules when the potential difference between each pixel electrode and the common electrode is zero. FIG. 13 is a diagram showing the alignment of liquid crystal molecules when there is a potential difference between each pixel electrode and the common electrode.

  In the liquid crystal display panel of the second embodiment, the first pixel electrode 106a and the second pixel electrode 106b are connected to the same source electrode 105, and the potential difference between the first pixel electrode 106a and the common electrode 205, the second The potential difference between the pixel electrode 106b and the common electrode 205 is always constant. At this time, if the potential difference between the pixel electrodes 106a and 106b and the common electrode 205 is zero, the liquid crystal molecules 301 in the liquid crystal material 3 are aligned perpendicularly to the substrate plane as shown in FIG. .

  When a potential difference is generated between the pixel electrodes 106a and 106b and the common electrode 205, for example, as shown in FIG. 13, the orientation of the liquid crystal molecules 301 changes in a direction horizontal to the substrate plane. At this time, since the third insulating layer 109 and the fourth insulating layer 110 are provided on the first pixel electrode 106a, as described in the first embodiment, the third insulating layer 109 and the fourth insulating layer 110 are formed. Near the boundary, the electric field (lines of electric force) EF is inclined with respect to the substrate plane, and is aligned at a different angle from the liquid crystal molecules 301 in other regions. On the other hand, since there is no insulating layer corresponding to the third insulating layer 109 and the fourth insulating layer 110 over the second pixel electrode 106b, the entire region on the second pixel electrode 106b as shown in FIG. The liquid crystal molecules 301 are aligned at the same angle.

  FIGS. 14 to 17 are schematic diagrams for explaining the function and effect of the liquid crystal display panel according to the second embodiment. FIG. 14 shows a reflective area and a transmissive area for comparison with the liquid crystal display panel according to the second embodiment. 15 is a schematic cross-sectional view showing a configuration example of a display panel having the same, FIG. 15 is a diagram showing the relationship between potential difference, transmittance, and reflectance in each region in the configuration example shown in FIG. 14, and FIG. FIG. 17 is a cross-sectional view schematically showing the relationship between the reflective region and the transmissive region, and FIG. 17 is a diagram showing the relationship between the potential difference of each region, the transmittance, and the reflectance in the configuration example shown in FIG. 15 and 17, VPC is a potential difference between the pixel electrode and the common electrode, TR is the transmittance of the transmissive region, and RR is the reflectance of the reflective region.

  In describing the function and effect of the liquid crystal display panel according to the second embodiment, as shown in FIG. 14, the first pixel electrode 106a and the second pixel electrode 106b are provided, and the third insulating layer 109 and the fourth pixel electrode are provided. A relationship between the potential difference VPC, the transmittance TR, and the reflectance RR in a display panel without the insulating layer 110 will be described.

  In the configuration shown in FIG. 14, the light LB passes through the liquid crystal material 3 only once in the transmission region, whereas the light LA passes through the liquid crystal material 3 twice in the reflection region. At this time, in the configuration in which the thicknesses of the liquid crystal materials in the reflective region and the transmissive region are substantially equal as in the second embodiment, the optical path length of the reflective region is twice the optical path length of the transmissive region. Therefore, if the electric field intensity of the reflective region and the transmissive region is the same, the degree of influence of the reflective region on the light passing through the liquid crystal material 3 is twice that of the transmissive region. As a result, the BV characteristic (brightness-voltage characteristic) differs between the reflective area and the transmissive area.

  At this time, the relationship between the potential difference VPC between the first pixel electrode 106a and the common electrode 205 in the reflective region and the reflectance RR is, for example, as shown by a black square in FIG. On the other hand, the relationship between the potential difference VPC between the second pixel electrode 106b and the common electrode 205 in the transmissive region and the transmittance TR is, for example, as shown by white circles in FIG. As described above, when the first pixel electrode 106a and the second pixel electrode 106b are formed on the same plane, the potential difference VPC at which the reflectance RR increases in the reflective region is around 3V, and the transmittance TR is in the transmissive region. The increasing potential difference VPC is between 4V and 5V. Therefore, in the display panel having such a configuration, for example, the potential difference VPC must be set to 3 V when displaying at the maximum luminance, and the transmittance TR of the transmissive region is lowered.

  On the other hand, when the third insulating layer 109 and the fourth insulating layer 110 are provided on the first pixel electrode 106a in the reflective region as in the second embodiment, the insulating layer is thicker in the reflective region than in the transmissive region. The strength of the electric field in the region can be made lower than the strength of the electric field in the transmission region. At this time, by embedding the fourth insulating layer 110 having a dielectric constant different from that of the third insulating layer 109, as shown in FIG. 17, the potential difference VPC that increases the reflectance RR of the reflective region and the transmittance of the transmissive region. The potential difference VPC at which TR becomes high can be matched. In FIG. 17, the distribution indicated by a black square is a distribution when the dielectric constant ε1 of the third insulating layer 109 is 3.3 and the dielectric constant ε2 of the fourth insulating layer 110 is 6.7. In FIG. 17, the distribution indicated by the broken line is a distribution when the dielectric constant ε2 of the fourth insulating layer 110 is 3.3.

  As described above, according to the liquid crystal display panel of the second embodiment, by providing the third insulating layer 109 and the fourth insulating layer 110 on the first pixel electrode 106a in the reflective region, The orientation of the liquid crystal molecules 301 can be controlled and the display device can have a wide viewing angle.

  In addition, by providing the third insulating layer 109 and the fourth insulating layer 110 on the first pixel electrode 106a in the reflective region, the potential difference VPC that increases the reflectance RR in the reflective region and the transmittance TR in the transmissive region are high. Therefore, the difference in luminance between the reflection region and the transmission region can be reduced.

  In addition, since the orientation of the liquid crystal molecules 301 is controlled by the thickness of the third insulating layer 109 and the shape (overlapping area) of the fourth insulating layer 110, the pixel electrode 106 may be flat and can easily achieve desired luminance-voltage characteristics. Can be realized.

  Further, since the surface of the third insulating layer 109 on the pixel electrode 106 can be easily flattened, high contrast can be easily achieved.

  In the second embodiment, for example, the SiN CVD film is etched to form the fourth insulating layer 110. However, the fourth insulating layer 110 is not limited to this, and may be formed by various methods and materials. it can. Further, the shape of the fourth insulating layer 110 is not limited to the shape shown in FIGS. 8 and 9 and may be other shapes.

  18 and 19 are schematic views for explaining a modification of the second embodiment. FIG. 18 is a plan view showing a configuration example of one pixel region of the first substrate. FIG. 19 is a plan view of FIG. It is sectional drawing seen by the FF 'line.

  In the liquid crystal display panel of Example 2, the fourth insulating layer 110 is provided to generate an oblique electric field EF between the first pixel electrode 106 a and the common electrode 205. Therefore, for the fourth insulating layer 110, for example, a spherical insulator material (for example, beads) as shown in FIGS. 18 and 19 can be used. The shape of the fourth insulating layer 110 is not limited to a spherical shape, and may be any insulating particle.

  When the fourth insulating layer 110 is formed using the spherical insulator material, for example, first, a method in which a photosensitive resin used for forming the third insulating layer 109 is mixed with the spherical insulator material is printed. To selectively apply the first pixel electrode 106a. And only the said photosensitive resin is apply | coated to the area | region which was not apply | coated at this time by the second printing. At this time, a material having a refractive index different from that of the photosensitive resin is used as the spherical insulator material.

  In the liquid crystal display panel provided with the spherical fourth insulating layer 110 in this way, the light incident from the second substrate 2 side and the first pixel electrode at the interface between the third insulating layer 109 and the fourth insulating layer 110. The light reflected by 106a can be efficiently scattered, and glare in the reflection region can be prevented.

  20 to 22 are schematic views for explaining an application example of the second embodiment. FIG. 20 is a plan view showing a configuration example of one pixel region of the first substrate. FIG. 21 is a plan view of FIG. A sectional view taken along line GG ′, FIG. 22 is a schematic sectional view for explaining the function and effect.

  In the second embodiment, for example, as shown in FIGS. 8 and 9, the second pixel 106b in the transmissive region is provided with an opening 114 for controlling the alignment of the liquid crystal molecules 301 in the transmissive region. However, the orientation control method according to the present invention is also applied to the transmission region, and instead of providing the opening 114, an insulating layer corresponding to the third insulating layer 109 and the fourth insulating layer 110 may be provided. That is, as illustrated in FIGS. 20 and 21, the fifth insulating layer 115 and the sixth insulating layer 116 embedded in the fifth insulating layer 115 may be provided over the second pixel 106 b in the transmissive region. At this time, for example, the fifth insulating layer 115 may be formed using the same material as the third insulating layer 109, and the sixth insulating layer 116 may be formed using the same material as the fourth insulating layer 110.

  In this way, when a potential difference is generated between the pixel electrodes 106a and 106b and the common electrode 205, for example, as shown in FIG. 22, an oblique electric field EF is generated in each of the reflective region and the transmissive region. Therefore, the alignment of the liquid crystal molecules 301 in the transmissive region can be controlled as in the case where the opening 114 is provided in the second pixel electrode 106b.

  The present invention has been specifically described above based on the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. is there.

It is a schematic diagram which shows schematic structure of the liquid crystal display panel which the liquid crystal display device to which this invention is applied has, and is a top view of a liquid crystal display panel. FIG. 2 is a cross-sectional view taken along line A-A ′ of FIG. 1. It is a schematic diagram which shows schematic structure of the liquid crystal display panel of Example 1 by this invention, and is a top view which shows the structural example of one pixel area | region. FIG. 4 is a cross-sectional view taken along line B-B ′ of FIG. 3. FIG. 4 is a cross-sectional view taken along line C-C ′ of FIG. 3. FIG. 10 is a schematic diagram for explaining the operational effect of the display panel of the first embodiment, and is a cross-sectional view showing the distribution of equipotential lines when there is a potential difference between the pixel electrode and the common electrode. FIG. 6 is a schematic diagram for explaining the operational effect of the display panel of the first embodiment, and is a cross-sectional view illustrating the alignment of liquid crystal molecules when there is a potential difference between the pixel electrode and the common electrode. It is a schematic diagram which shows schematic structure of the display panel of Example 2 by this invention, and is a top view which shows the structural example of one pixel area. FIG. 9 is a cross-sectional view taken along line D-D ′ of FIG. 8. It is sectional drawing seen from the E-E 'line of FIG. 6 is a schematic cross-sectional view for explaining a reflective region and a transmissive region of the liquid crystal display panel of Example 2. FIG. It is a schematic diagram for demonstrating operation | movement of the liquid crystal display panel of the present Example 2, and is a figure which shows the orientation of a liquid crystal molecule when the potential difference of each pixel electrode and a common electrode is zero. It is a schematic diagram for demonstrating operation | movement of the liquid crystal display panel of the present Example 2, and is a figure which shows the orientation of a liquid crystal molecule when there exists a potential difference between each pixel electrode and a common electrode. It is a schematic diagram for demonstrating the effect of the liquid crystal display panel of this Example 2, and is a schematic cross section which shows the structural example of the display panel which has a reflective area and a transmissive area | region for comparing with the liquid crystal display panel of this Example 2. FIG. It is a figure which shows the relationship between the electric potential difference of each area | region in the structural example shown in FIG. 14, transmittance | permeability, and a reflectance. FIG. 10 is a schematic diagram for explaining the operational effect of the liquid crystal display panel of the second embodiment, and is a cross-sectional view schematically showing the relationship between the reflection region and the transmission region of the liquid crystal display panel of the second embodiment. FIG. 17 is a diagram illustrating a relationship between a potential difference, transmittance, and reflectance in each region in the configuration example illustrated in FIG. 16. FIG. 10 is a schematic diagram for explaining a modification of the second embodiment, and is a plan view showing a configuration example of one pixel region of the first substrate. It is sectional drawing seen by the F-F 'line | wire of FIG. It is a schematic diagram for demonstrating the application example of the said Example 2, and is a top view which shows the structural example of one pixel area | region of a 1st board | substrate. FIG. 21 is a schematic diagram for explaining an application example of the second embodiment and is a cross-sectional view taken along line G-G ′ of FIG. 20. It is a schematic cross section for demonstrating the effect in the structure shown in FIG. 20 and FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st board | substrate 2 ... 2nd board | substrate 101,201 ... Glass substrate 102 ... Gate line 103 ... Semiconductor layer 104 ... Drain line 105 ... Source electrode 106 ... Pixel electrode 106a ... 1st pixel electrode 106b ... 2nd Pixel electrode 107 ... first insulating layer 108 ... second insulating layer 109 ... third insulating layer 110 ... fourth insulating layer 111,206 ... alignment film 112a, 112b, 112c, 207a, 207b, 207c ... retardation plate 113, 208 DESCRIPTION OF SYMBOLS ... Polarizing plate 114 ... Opening 115 ... 5th insulating layer 116 ... 6th insulating layer 202 ... Black matrix 203 ... Color filter 204 ... Overcoat layer 205 ... Common electrode 3 ... Liquid crystal material 301 ... Liquid crystal molecule 4 ... Sealing material 5 ... Backlight unit ES ... equipotential surface EF ... electric field (lines of electric force)
LA: Light from outside LB: Light from backlight unit

Claims (4)

A plurality of gate lines and a plurality of drain lines are arranged in a matrix, and a first electrode having a pixel electrode in a pixel region surrounded by two adjacent gate lines and two adjacent drain lines A liquid crystal material is sandwiched between a substrate and a second substrate having a common electrode, and when the potential difference between the pixel electrode and the common electrode is zero, the liquid crystal material contains liquid crystal molecules in each of the substrates. A liquid crystal display device having a liquid crystal display panel oriented in the vertical direction of the surface,
The first substrate includes a first insulating layer that overlaps the entire area of the pixel electrode on the surface of the pixel electrode that faces the common electrode;
A second insulating layer embedded in the first insulating layer and having an overlapping area smaller than the area of the pixel electrode;
A liquid crystal display device, wherein a dielectric constant of the first insulating layer is different from a dielectric constant of the second insulating layer. The first substrate has two pixel electrodes having different distances from the common electrode in one pixel region,
The first pixel electrode that is far from the common electrode is made of a conductive material that reflects the light incident from the second substrate side and emits the light to the second substrate side, and the distance from the common electrode is short. The second pixel electrode is made of a conductive material that transmits light incident from the back side of the first substrate and emits the light to the second substrate side,
The liquid crystal display device according to claim 1, wherein the first insulating layer and the second insulating layer are provided on a surface side of the first pixel electrode facing the common electrode. A third insulating layer that overlaps at least the entire area of the second pixel electrode on the surface of the second pixel electrode facing the common electrode, and is embedded in the third insulating layer and overlaps A fourth insulating layer having an area smaller than the area of the second pixel electrode;
The liquid crystal display device according to claim 2, wherein a dielectric constant of the third insulating layer is different from a dielectric constant of the fourth insulating layer.   4. The dielectric constant of the third insulating layer is equal to the dielectric constant of the first insulating layer, and the dielectric constant of the fourth insulating layer is equal to the dielectric constant of the second insulating layer. A liquid crystal display device according to 1.

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