JP2007102164A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal cell capable of enhancing orientation stability at a plurality of pixels, avoiding display unevenness due to orientation fluctuation and securing symmetry of a viewing angle and having a high display quality level. <P>SOLUTION: Transmission display regions 22 are disposed at both sides of a reflection display region 21 of a pixel electrode 6 in a pixel 5 of an array substrate 2. An insulating layer 35 having a first insulating layer 36 and second insulating layers 37 that face the transmission display regions 22 and the reflection display region 21 in the pixel electrode 6 is formed on a counter electrode 34 of a counter substrate 31. Second insulating layers 37 exist at both sides of the first insulating layer 36. The motion of liquid crystal molecules 41 is symmetrical with respect to the reflection display region 21. Liquid crystal orientation stability can be enhanced at a plurality of pixels 5. A defect such as unevenness in display due to orientation fluctuation of the liquid crystal molecules 41 in the liquid crystal layer 42 can be avoided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device in which a liquid crystal layer is interposed between an array substrate and a counter substrate.

  Conventionally, this type of liquid crystal display device uses liquid crystal elements and has features such as light weight, thinness, and low power consumption. Therefore, such as OA (Office Automation) equipment, information terminal devices, watches, televisions, etc. It is used in various fields. In particular, among liquid crystal display devices, liquid crystal display devices using thin film transistor (TFT) elements are excellent in responsiveness, so that many display devices such as mobile phones, televisions, computers, etc. It is used.

  In recent years, with the reduction in size and weight of information terminal devices, display devices with high definition and a wide viewing angle are required. This high definition is dealt with by miniaturizing the structure of the array substrate on which the TFT elements are provided. On the other hand, the viewing angle is a wide viewing angle liquid crystal using an OCB (Optically Compensated Bend) method using nematic liquid crystal, an MVA (Multi-domain Vertical Alignment) method, or an IPS (In-Plane Switching) method. A display device having a mode has been proposed.

  Furthermore, in recent years, since the frequency of use outdoors has increased, in addition to a transmissive display method capable of displaying by transmitting light, a transflective display having a reflective display method capable of displaying by partially reflecting light is also available. A transflective liquid crystal display system having a liquid crystal mode capable of realizing the above has been put into practical use. By combining these wide viewing angle liquid crystal modes and transflective liquid crystal modes, there is an increasing demand for high performance liquid crystal display devices with wide viewing angles and excellent outdoor visibility. .

  In particular, in a transflective liquid crystal display device capable of both transmissive display and reflective display, the thickness of the liquid crystal layer in the transmissive region capable of transmissive display and the reflective region capable of reflective display is independently controlled. There is a need. In general, a projecting protruding portion under a counter electrode in a portion facing a reflective region for applying a voltage to a liquid crystal layer between the array substrate and a counter substrate disposed opposite to the array substrate Since the thickness of the liquid crystal layer in this reflective region is controlled, the number of processes for forming this protrusion increases.

Therefore, in an MVA type liquid crystal display device in which the alignment is divided by a dielectric structure such as a resist material, the dielectric layer is formed also in the reflection region using the alignment dividing dielectric layer, and the liquid crystal layer is retarded by a voltage drop. A configuration is known in which the thickness of the liquid crystal layer in the apparent reflection region is reduced by controlling the above (for example, see Patent Document 1).
JP 2003-107508 A

  However, in the above-described MVA liquid crystal display device, a convex dielectric layer for alignment control unique to the MVA system and a convex dielectric layer for adjusting the thickness of the liquid crystal layer in the reflective region are provided. Each of them needs to be formed independently above and below the pixel electrodes of the array substrate. Therefore, the number of processes or the number of masks for manufacturing the liquid crystal display device and the management items such as the film thickness control increase, so it is not easy to improve the liquid crystal alignment stability in the pixel, and display unevenness, etc. Since it is not easy to avoid defects, there is a problem that it is not easy to improve display quality.

  The present invention has been made in view of these points, and an object thereof is to provide a liquid crystal display device with good display quality.

  The present invention relates to a light-transmitting substrate, a plurality of pixels provided in a matrix on one main surface of the light-transmitting substrate, a reflection region that is provided in the plurality of pixels and is visible by reflection of light, and these An array substrate provided on both sides of the reflection region across the reflection region and provided with a transmission region that can be visually recognized by light transmission, and disposed opposite to one main surface of the light-transmitting substrate of the array substrate A translucent substrate, and a main surface of the array substrate on the translucent substrate opposite to the main surface of the array substrate, are provided to face at least a part of each of the transmission region and the reflection region of the plurality of pixels. A counter substrate provided with the insulating layer, and a liquid crystal layer interposed between the array substrate and the counter substrate.

  Then, a transmissive region is provided on both sides of the reflective region across the reflective region of each of the plurality of pixels provided in a matrix on one main surface of the light transmissive substrate of the array substrate, and the light transmissive substrate of the counter substrate An insulating layer was provided on one side of the array substrate opposite to one main surface of the array substrate so as to face at least a part of each of the transmission region and the reflection region of the plurality of pixels.

  According to the present invention, since the movement of the liquid crystal layer controlled by the insulating layer in the reflective region is symmetric by the transmissive regions located on both sides of the reflective region, the alignment stability in each of the plurality of pixels can be improved. At the same time, display unevenness due to orientation fluctuations and symmetry of viewing angle can be secured, so that display quality can be improved.

  The configuration of the first embodiment of the liquid crystal display device of the present invention will be described below with reference to FIGS.

  1 to 3, reference numeral 1 denotes a liquid crystal cell as a liquid crystal display device. The liquid crystal cell 1 is a wide-view transflective liquid crystal display element having a reflective display portion and a transmissive display portion. The liquid crystal cell 1 is a display device having a vertical alignment type liquid crystal mode using a wide viewing angle mode called an MVA (Multi-domain Vertical Alignment) method.

  The liquid crystal cell 1 includes an array substrate 2 having a substantially rectangular flat plate shape. The array substrate 2 has a substantially transparent rectangular flat glass substrate 3. The glass substrate 3 is a translucent substrate as a transparent substrate having translucency and electrical insulation. On the surface that is one main surface of the glass substrate 3, a plurality of pixels 5 are arranged in a matrix. Each of the plurality of pixels 5 is formed in an elongated rectangular shape in plan view that is a long shape along the vertical direction of the glass substrate 3. Further, in each of the plurality of pixels 5, a pixel electrode 6, an auxiliary capacitor (not shown) that is a pixel auxiliary capacitor as a storage capacitor, and a thin film transistor (TFT) 7 are arranged one by one as one pixel constituent element. .

  On the glass substrate 3, a plurality of scanning lines 11 as first wirings are arranged along the width direction of the glass substrate 3. These scanning lines 11 are gate electrode wirings formed of a conductive film, and are spaced in parallel at equal intervals in the lateral direction of the glass substrate 3. Further, a plurality of signal lines 12 as second wirings are arranged on the glass substrate 3 along the vertical direction of the glass substrate 3. These signal lines 12 are image signal wirings as electrode wirings formed of a conductive film, and are spaced in parallel at equal intervals in the lateral direction of the glass substrate 3. These scanning lines 11 and signal lines 12 are formed by patterning after a conductive film is formed by sputtering or the like.

  Further, the scanning lines 11 and the signal lines 12 are wired in a lattice pattern so as to intersect perpendicularly on the glass substrate 3. A pixel 5 is provided in each rectangular region surrounded by the scanning line 11 and the signal line 12. Further, the pixel electrode 6, the auxiliary capacitor, and the thin film transistor 7 are provided for each pixel 5 corresponding to each intersection of the scanning line 11 and the signal line 12.

  Further, between the scanning lines 11 on the glass substrate 3, auxiliary capacitance (Cs) lines 13 serving as capacitance lines, which are a plurality of metal electrodes along the longitudinal direction of the scanning lines 11, are arranged in the width direction of the glass substrate 3. It is arranged along. These auxiliary capacitance lines 13 are provided in a substantially central portion along the vertical direction of the glass substrate 3 between the scanning lines 11 so as to be spaced apart in parallel to the scanning lines 11. Further, these auxiliary capacitance lines 13 are electrically connected to auxiliary capacitances provided in each pixel 5. The auxiliary capacitance line 13 constitutes a part of the pixel electrode 6 provided in each pixel 5. Further, a reflection surface 14 that reflects light incident on the surface of the auxiliary capacitance line 13 is formed on the surface that is one main surface of the auxiliary capacitance line 13.

The pixel electrode 6 of each pixel 5 is provided in a rectangular area partitioned by a plurality of scanning lines 11 and signal lines 12. Then, on both sides of the auxiliary capacitance line 13 of these pixel electrodes 6, transparent electrodes 15 are respectively laminated in succession to the auxiliary capacitance line 13. These transparent electrodes 15 are transmissive pixel electrodes made of, for example, transparent ITO (Indium Tin Oxide) and cover regions between the signal lines 12 on both sides of the auxiliary capacitance line 13 in each pixel 5. . Therefore, these transparent electrodes 15 are provided on both sides of the auxiliary capacitance line 13 in each pixel 5 and are laminated in the same layer as the auxiliary capacitance line 13 .

In here, the region where the auxiliary capacitance line 13 are stacked in each pixel 5, a reflective display region 21 as a reflection area capable of displaying the reflection type is visible in the reflection of light. In addition, a region where the transparent electrode 15 in each pixel 5 is laminated becomes a transmissive display region 22 as a transmissive region capable of displaying in a transmissive manner that can be visually recognized by transmitting light. Therefore, in each pixel 5, the reflective display region 21 is arranged in a rectangular flat plate over the entire width direction of each pixel 5 in the center in the longitudinal direction of the pixel electrode 6 in each pixel 5. Is provided. Further, since the transparent electrode 15 and the auxiliary capacitance line 13 of the pixel electrode 6 are flush with each other in the reflective display area 21 and the transmissive display area 22, cell gaps 23, 24 are formed equally.

  Further, in each of these pixels 5, a transmissive display area 22 is arranged in a rectangular flat plate shape over the entire width direction of each of these pixels 5 on both sides along the longitudinal direction of the pixel electrode 6 of the reflective display area 21. Has been provided. Therefore, in these pixels 5, the transmissive display areas 22 are provided symmetrically, that is, line-symmetrically, on both sides of the reflective display area 21. Further, each of the reflective display area 21 and the transmissive display area 22 has substantially the same relationship between the voltage applied to the reflective display area 21 and the transmissive display area 22 and the luminance characteristic, that is, the applied voltage-luminance characteristic. Are equally formed.

  On the glass substrate 3 including the pixel electrodes 6, an alignment film 28 formed by, for example, polyimide alignment processing is laminated. The alignment film 28 is configured by applying alignment means on the surface of the glass substrate 3 covering the pixel electrode 6. The alignment film 28 is an alignment treatment layer formed by applying a vertical alignment film with a film thickness of, for example, 70 nm or more and 90 nm or less. The alignment film 28 is aligned in a predetermined direction and covers each of the pixel electrode 6, the thin film transistor 7, the scanning line 11, the signal line 12, and the auxiliary capacitance line 13 in each pixel 5.

  On the other hand, a rectangular flat plate-like counter substrate 31 as a common substrate is disposed facing the array substrate 2. The counter substrate 31 includes a substantially transparent rectangular flat glass substrate 32. The glass substrate 32 is a translucent substrate as a transparent transparent substrate having translucency and electrical insulation. A counter electrode 34, which is a common electrode made of ITO, is laminated on the surface which is one main surface of the glass substrate 32 facing the array substrate 2.

  On the counter electrode 34, an insulating layer 35 having a convex projecting structure protruding from the surface of the counter electrode 34 is laminated and disposed. The insulating layer 35 is an insulating structure and is made of a photosensitive acrylic resist. Further, the insulating layer 35 is formed with a film thickness of about 1.5 μm ± 0.2 μm, for example. In addition, the insulating layer 35 is provided with at least one of the reflective display region 21 and the transmissive display region 22 of the pixel electrode 6 in each pixel 5 of the array substrate 2 when the counter substrate 31 is opposed to the array substrate 2. It is provided in a substantially lattice shape so as to face the part. The insulating layer 35 includes a plurality of convex first insulating layers 36 facing the storage capacitor line 13 of the array substrate 2 when the counter substrate 31 is opposed to the array substrate 2.

  Specifically, the first insulating layer 36 is a reflective region insulating layer as a reflective convex structure provided facing the reflective display region 21 in each pixel 5 of the array substrate 2. That is, the first insulating layer 36 is provided at a position overlapping the reflective display region 21 of the array substrate 2, and is disposed along the lateral direction of the glass substrate 32 of the counter substrate 31. Therefore, the first insulating layer 36 is formed in a rectangular shape in plan view that is equal to a part of the auxiliary capacitance line 13 located in each pixel 5 of the array substrate 2. Further, the first insulating layer 36 is provided for MVA orientation control and is formed to have a substantially constant film thickness.

  The first insulating layer 36 has a longitudinal direction along the longitudinal direction of the auxiliary capacitance line 13 on the array substrate 2 and a width dimension equal to the width dimension of the auxiliary capacitance line 13. The first insulating layer 36 is formed in an elongated rectangular shape in plan view having a longitudinal dimension equal to the width dimension of each pixel 5 of the array substrate 2. Further, the first insulating layer 36 is arranged so that the edge shape of the peripheral portion which is the peripheral portion of the first insulating layer 36 is symmetric with respect to the longitudinal center of the insulating layer 35. .

  Here, the edge shape of the peripheral portion which is the peripheral portion of the pixel electrode 6 of each pixel 5 of the array substrate 2 is also arranged to be symmetric with respect to the longitudinal center of the insulating layer 35. Here, the first insulating layer 36 is configured by using a resist material that can be processed in the manufacturing process of the existing array substrate 2. In particular, it is preferable to use a material used for the second insulating layer 37 for MVA orientation control as the first insulating layer 36.

  Further, a plurality of convex second insulating layers 37 disposed in the longitudinal direction of the glass substrate 32 of the counter substrate 31 are stacked on the counter electrode 34. The second insulating layer 37 is a transmissive region insulating layer as a transmissive portion convex structure provided facing the transmissive display region 22 in each pixel 5 of the array substrate 2. The second insulating layer 37 is provided in the same layer as the first insulating layer 36, and is formed simultaneously with the same material and the same process as the first insulating layer 36, that is, in the same process. .

  That is, the second insulating layer 37 is provided on both sides of the first insulating layer 36. The second insulating layer 37 is provided at a position overlapping the transmissive display region 22 of the array substrate 2 when the counter substrate 31 is opposed to the array substrate 2. Therefore, the second insulating layer 37 is formed along the longitudinal direction of the array substrate 2 so as to be positioned at the center in the width direction between the signal lines 12 of the array substrate 2.

  Therefore, the second insulating layer 37 is laminated on the counter electrode 34 of the counter substrate 31 at a pitch equal to the width dimension between the signal lines 12 of the array substrate 2. The second insulating layer 37 has a longitudinal direction orthogonal to the longitudinal direction of the first insulating layer 36 and is formed to have a width slightly larger than the width of the signal line 12 of the array substrate 2. Yes.

  On the glass substrate 32 including the insulating layer 35 and the counter electrode 34 constituted by the first insulating layer 36 and the second insulating layer 37, for example, an alignment film 38 formed by an alignment process of polyimide. Are stacked. The alignment film 38 is configured by applying alignment means to the surface of the glass substrate 32 covering the insulating layer 35 and the counter electrode 34. The alignment film 38 is an alignment treatment layer formed by applying a vertical alignment film with a film thickness of, for example, 70 nm or more and 90 nm or less. The alignment film 38 is subjected to an alignment process in a certain direction and covers each of the counter electrode 34 and the insulating layer 35 on the glass substrate 32.

  Further, the alignment film 38 and the alignment film 28 of the array substrate 2 have a predetermined gap, for example, 3.5 μm ± 0.3 μm, through a spacer (not shown) as a substrate gap material between the alignment films 28 and 38. In this manner, the liquid crystal sealing area A which is a liquid crystal injection space is formed to be opposed and bonded together by a sealing material (not shown). In the liquid crystal sealing region A, liquid crystal molecules 41 as a liquid crystal composition are injected and sealed to form a liquid crystal layer 42 as a light modulation layer. Therefore, the liquid crystal layer 42 is sandwiched and held between the alignment film 28 of the array substrate 2 and the alignment film 38 of the counter substrate 31. Here, the liquid crystal layer 42 facing each of the reflective display area 21 and the transmissive display area 22 of each pixel 5 of the array substrate 2 faces each of the reflective display area 21 and the transmissive display area 22 of each pixel 5. A voltage is applied through the counter electrode 34.

  As the liquid crystal molecules 41 of the liquid crystal layer 42, for example, a liquid crystal material having negative (Nn) conductivity anisotropy is used. Therefore, the liquid crystal cell 1 is provided with a vertical alignment type liquid crystal mode in which the liquid crystal molecules 41 are aligned vertically. Further, quarter-wave plates 43 and 44, which are rectangular plate-like optical filters, are laminated on the back surfaces of the glass substrate 3 and 32 of the array substrate 2 and the counter substrate 31 of the liquid crystal cell 1, respectively. Has been pasted. Further, linear polarizing plates 45 and 46, which are half-wave plates, are laminated and pasted on the quarter-wave plates 43 and 44, respectively.

  Here, as these linearly polarizing plates 45 and 46, polarizing elements generally called circularly polarizing plates are used so that electro-optical switching can be effectively performed in the reflective display region 21 in each pixel 5 of the array substrate 2. It has been. As this circularly polarizing plate, a structure in which a quarter-wave plate is combined with a linearly polarizing element, or a quarter-wave plate and a half-wave plate are stacked to suppress light transmittance conversion by wavelength. Other configurations can be used. Furthermore, an optical element having a negative phase difference can be added to these linearly polarizing plates 45 and 46 from the viewpoint of widening the viewing angle.

  As a result, the liquid crystal cell 1 switches the thin film transistor 7 of each pixel 5 and applies a video signal to the pixel electrode 6 to control the orientation of the liquid crystal molecules 41 in the liquid crystal layer 42. By modulating each of the light reflected by the reflective display region 21 of the pixel electrode 6 and the light transmitted through the transmissive display region 22 of the pixel electrode 6, a predetermined image is made visible.

  Next, a method for manufacturing the liquid crystal display device according to the first embodiment will be described.

  First, the array substrate 2 in which the pixel electrodes 6 are arranged in a matrix is created.

  Further, an insulating layer 35 is formed on the counter electrode 34 of the counter substrate 31 by using a photosensitive acrylic resist so that the pixel electrode 6 of the array substrate 2 is opposed to the pixel electrode 6.

At this time, in the pixel electrode 6 on the array substrate 2, a region facing the first insulating layer 36 of the counter substrate 31 facing the pixel electrode 6 is formed by a metal electrode that reflects light to form an auxiliary capacitor. Line 13. Further, a region facing the second insulating layer 37 of the counter substrate 31 in the pixel electrode 6 on the array substrate 2 is formed by the transparent electrode 15 that transmits light.

  Further, alignment films 28 and 38 are formed by applying a vertical alignment film to the surfaces of the array substrate 2 and the counter substrate 31 in contact with the liquid crystal layer 42, respectively.

  Next, the array substrate 2 and the counter substrate 31 are bonded together with a sealing material through a spacer while ensuring a gap.

  Thereafter, the liquid crystal sealing region A between the array substrate 2 and the counter substrate 31 is filled with liquid crystal molecules 41 and sealed to form a liquid crystal layer 42.

  Further, the quarter-wave plates 43 and 44 and the linear polarizing plates 45 and 46 are arranged on the back surfaces of the array substrate 2 and the counter substrate 31, respectively, so as to have the reflective display area 21 and the transmissive display area 22, respectively. A transmissive liquid crystal cell 1 is formed.

  As a result, when the characteristics of the linearly polarized state obtained by removing the circularly polarizing plate from the linearly polarizing plates 45 and 46 of the liquid crystal cell 1 were confirmed, as shown in FIG. The CR (Computed Radiography: computer X-ray imaging) viewing angle could be confirmed, and it was confirmed that the display had no display unevenness such as roughness.

  On the other hand, as in the first comparative example shown in FIGS. 7 to 9, the auxiliary capacitance line 13 is wired to one end portion of the pixel electrode 6 in the longitudinal direction of the array substrate 2 and faces the auxiliary capacitance line 13. In the case of the liquid crystal cell 1 in which the first insulating layer 36 is formed at one end in the longitudinal direction of the insulating layer 35 as described above, the linearly polarized state is obtained by removing the circularly polarizing plate from the linearly polarizing plates 45 and 46 of the liquid crystal cell 1. As shown in FIG. 10, the asymmetrical CR viewing angle in the vertical direction of the liquid crystal cell 1 was confirmed, and it was confirmed that display unevenness such as roughness was generated.

  Here, in the conventional liquid crystal cell 1 in which the transmissive display region 22 is arranged only at one end or the other end in the longitudinal direction of the pixel 5 with respect to the reflective display region 21 of the array substrate 2, the reflective display region 21 of the liquid crystal cell 1. The movement of the liquid crystal molecules 41 controlled by the first insulating layer 36 and the peripheral edge of the pixel electrode 6 becomes asymmetric in the pixel 5, causing problems such as unevenness due to alignment fluctuations and asymmetry of the viewing angle. It was easy.

Therefore, in the liquid crystal cell 1 of the first embodiment, as described above, the transmissive display areas 22 are arranged on both sides of the reflective display area 21 of the pixel electrode 6 in each pixel 5 of the array substrate 2. together, an insulating layer 35 having a first insulating layer 36 and the second insulating layer 37 opposite to each of the reflective display region 2 1 and a transmissive display region 2 2 in each pixel 5 of the array substrate 2 of the counter substrate 31 It was formed on the counter electrode 34.

  As a result, since the second insulating layer 37 exists on both sides of the first insulating layer 36, the liquid crystal molecules 41 controlled at the peripheral portion of the first insulating layer 36 and the pixel electrode 6 in each pixel 5. Are symmetrical about the reflective display region 21 in the transmissive display region 22 arranged on both sides of the reflective display region 21. Accordingly, the stability of the liquid crystal alignment in each of the plurality of pixels 5 can be improved, and defects such as display unevenness due to the alignment fluctuation of the liquid crystal molecules 41 in the liquid crystal layer 42 can be avoided, so that the asymmetry of the viewing angle can be avoided. For this reason, the symmetry of the viewing angle in each pixel 5 of the liquid crystal cell 1 can be secured, and the overall image quality characteristics of the liquid crystal cell 1 can be improved. Therefore, since the display quality of the liquid crystal cell 1 can be improved, the transflective liquid crystal cell 1 having a wide viewing angle can be easily provided.

  Further, as the liquid crystal display mode of the liquid crystal cell 1, a vertical alignment type liquid crystal display method in which liquid crystal molecules 41 having negative dielectric anisotropy are vertically aligned is used, and in particular, a wide viewing angle mode which is an MVA method is adopted. ing. Therefore, by using the liquid crystal cell 1 having the vertical alignment type liquid crystal display mode using the MVA method, the horizontal alignment represented by the TN (Twist Nematic) method and the IPS method which have been put to practical use has been used. The manufacturing process of the liquid crystal cell 1 of the type, that is, the rubbing process during the manufacturing process can be eliminated. Therefore, generation of dust in the rubbing treatment process when manufacturing the liquid crystal cell 1 and defects such as uneven rubbing can be avoided, and the productivity of the liquid crystal cell 1 can be improved, so that the viewing angle characteristics are excellent. The transmissive liquid crystal cell 1 can be manufactured with high yield.

  Further, in the MVA method, the inclination direction of the liquid crystal molecules 41 in the liquid crystal layer 42 is set so that the insulating layer 35 formed on the counter electrode 34 of the counter substrate 31 and the outer peripheral edge (fringe−) which is a cutout portion of the counter electrode 34. field: fringe field). Therefore, the second insulating layer 37 is formed on both sides of the first insulating layer 36 of the counter substrate 31 as described above, so that the second electrode facing the transparent electrode 15 in each pixel 5 of the array substrate 2 is formed. The direction of inclination of the liquid crystal molecules 41 can be controlled by the insulating layer 37. At this time, by forming the second insulating layer 37 with a pattern using a photosensitive resist, the tilt direction of the liquid crystal molecules 41 in the portion of the array substrate 2 facing the transmissive display region 22 in each pixel 5 is arranged. Can be controlled in any direction.

  Further, conventionally, the thickness of the liquid crystal layer 42 in the reflective display region 21 of the array substrate 2 is controlled by the insulating layer on the counter substrate 31. However, in this case, it is necessary to independently form an insulating layer for controlling the orientation unique to the MVA mode and an insulating layer for controlling the thickness of the liquid crystal layer 42 for reflective display independently above and below the counter electrode 34. Therefore, the number of processes and the number of masks when manufacturing the liquid crystal cell 1 are increased, and management items such as film thickness control of these insulating layers are increased, which is likely to cause a decrease in yield.

  In contrast, in the reflective display region 21 of the liquid crystal cell 1 of the first embodiment, the same process and the same material are applied to the same layer as the second insulating layer 37 provided for the MVA alignment control of the transmissive display region 22. The first insulating layer 36 is formed in the above. As a result, cost increases such as an increase in the number of processes and masks when the liquid crystal cell 1 is manufactured, and the first insulating layer 36 and the second insulating layer 37 for controlling the thickness of the liquid crystal layer 42 with good braking are provided. Management items such as film thickness control can be reduced to the same level as the conventional MVA type liquid crystal cell 1.

  Further, the first insulating layer 36 facing the reflective display region 21 of each pixel 5 of the liquid crystal cell 1 is matched with the movement of the liquid crystal molecules 41 by the peripheral edge of each pixel electrode 6 of the array substrate 2 of this liquid crystal cell 1. This is very important. For this reason, it is preferable that the shape of the peripheral edge of the pixel electrode 6 and the peripheral edge of the first insulating layer 36 be arranged symmetrically with respect to the longitudinal center of the insulating layer 35. That is, the most preferable arrangement state is that the first insulating layer 36 is provided at the center in the longitudinal direction of the insulating layer 35. However, in practice, the second insulating layer 37 may be disposed on both sides of the first insulating layer 36.

  Further, as a material for forming the first insulating layer 36, a photosensitive resist material that can be processed in the manufacturing process of the existing array substrate 2 can be used. In particular, the use of an alignment control material for the MVA system as the material of the first insulating layer 36 is advantageous in controlling the voltage-temperature (VT) characteristics due to the alignment controllability and voltage drop in the reflective display region 21. To preferred. The first insulating layer 36 may have a substantially constant film thickness and the same shape as the auxiliary capacitance line 13 in the pixel electrode 6 of each pixel 5, but the color reproducibility of the liquid crystal cell 1 is reflected and displayed. When it is necessary to match each of the region 21 and the transmissive display region 22 with high accuracy, it is preferable that the applied voltage-luminance characteristics in the reflective display region 21 and the transmissive display region 22 are matched within ± 100 mV.

  Accordingly, the liquid crystal electro-optic characteristic of the reflective display region 21 that has been conventionally controlled by only one parameter of the thickness of the liquid crystal layer 42 is the voltage by the insulating layer 35 provided on the counter electrode 34 of the counter substrate 31 as the first parameter. It can be controlled by three parameters: a drop, a thickness of the liquid crystal layer 42 controlled by the insulating layer 35 as a second parameter, and a tilt direction of the liquid crystal molecules 41 controlled by a pattern of the insulating layer 35 as a third parameter.

  In the first embodiment, the first insulating layer 36 on the counter electrode 34 of the counter substrate 31 is formed in a flat planar view rectangular shape having substantially the same film thickness, as shown in FIGS. As in the second embodiment, the first insulating layer 36 can be formed in an uneven shape in plan view. The first insulating layer 36 is formed in a substantially rectangular shape in plan view, and a plurality of elongated groove-like groove portions 51 are formed in the first insulating layer 36. These groove portions 51 are provided for the purpose of controlling the voltage applied to the liquid crystal layer 42 and the tilt direction of the liquid crystal molecules 41, and are formed in a concavo-convex structure with a pitch of 8 μm ± 2 μm, for example. Specifically, these groove portions 51 have first groove portions 52 formed along the longitudinal direction of the first insulating layer 36 from the center portion in the width direction of the first insulating layer 36. Further, these groove portions 51 have second groove portions 53 formed along the width direction of the first insulating layer 36 from the central portion in the longitudinal direction of the first insulating layer 36.

  Further, these groove portions 51 are formed by dividing each region of the first insulating layer 36 divided into, for example, a quarter by the first groove portion 52 and the second groove portion 53. The third groove portion 54 is formed so as to be spaced apart in parallel along a diagonal line connecting the end portions of the respective groove portions 53. These third groove portions 54 have a longitudinal direction along a direction inclined at an angle of about 45 degrees with respect to the longitudinal directions of the first groove portion 52 and the second groove portion 53. Further, the third groove portions 54 extend from a region in the first insulating layer 36 where the third groove portions 54 are provided to a part of an adjacent region via the first groove portion 52. Is formed. That is, these third groove portions 54 are formed so as to intersect the first groove portion 52.

  In addition, half-wave plates 56 and 57 are laminated between the quarter-wave plates 43 and 44 on the back surface of the array substrate 2 and the counter substrate 31 and the linear polarizing plates 45 and 46, respectively. Yes. As a result, the characteristics of the linearly polarized state obtained by removing the circularly polarizing plate from the linearly polarizing plates 45 and 46 of the liquid crystal cell 1 were confirmed. As in the case of the first embodiment, the liquid crystal cell 1 was almost completely Since the CR viewing angle having a symmetrical shape in the vertical direction can be confirmed, and it can be confirmed that the display has no display unevenness such as roughness, the same effects as those of the first embodiment can be obtained.

  On the other hand, as in the second comparative example shown in FIGS. 11 and 12, the auxiliary capacitance line 13 is wired at one end portion in the longitudinal direction of the pixel electrode 6 of the array substrate 2 and faces the auxiliary capacitance line 13. Thus, in the case of the liquid crystal cell 1 in which the concave and convex first insulating layer 36 is formed at one end in the longitudinal direction of the insulating layer 35, the circularly polarizing plate is removed from the linearly polarizing plates 45 and 46 of the liquid crystal cell 1. As a result of confirming the characteristics of the linear polarization state, as in the case of the first comparative example, a CR viewing angle having an asymmetric shape in the vertical direction of the liquid crystal cell 1 can be confirmed, and display unevenness such as roughness is generated. I was able to confirm.

  Furthermore, in order to set the voltage applied to the portion of the liquid crystal layer 42 facing the reflective display region 21 to a desired value, the adjustment has been conventionally performed by embedding the insulating layer 35 on the counter substrate 31 side. As in the liquid crystal cell 1 of the second embodiment, the groove 51 is provided in the first insulating layer 36 to form fine irregularities, and the apparent thickness of the first insulating layer 36 is controlled. At the same time, the tilt direction, which is the polar angle of the liquid crystal molecules 41, and the in-plane direction, which is the azimuth angle of the liquid crystal molecules 41, can be controlled simultaneously. Here, the groove 51 of the first insulating layer 36 is preferably formed with a fine period of, for example, 3 μm or more and 15 μm or less from the viewpoint of improving the alignment uniformity, but the voltage applied to the liquid crystal layer 42 From the viewpoint of balance of adjustment, transmittance, image quality, and the like, the period of these groove portions 51 can be made wider or narrower.

  In each of the above embodiments, the pixel electrode 6 in each pixel 5 is controlled by the thin film transistor 7. However, the pixel electrode is formed by a switching element other than the thin film transistor 7, such as a thin film diode (TFD). 6 can also be configured. Further, a simple matrix type liquid crystal cell 1 other than the active matrix type liquid crystal cell 1 can also be used correspondingly.

It is explanatory sectional drawing which shows a part of 1st Embodiment of the liquid crystal display device of this invention. It is an explanatory top view which shows a part of array substrate of a liquid crystal display device same as the above. It is an explanatory top view which shows a part of counter substrate of a liquid crystal display device same as the above. It is a graph which shows CR viewing angle of a liquid crystal display device same as the above. It is explanatory sectional drawing which shows a part of 2nd Embodiment of the liquid crystal display device of this invention. It is an explanatory top view which shows a part of counter substrate of a liquid crystal display device same as the above. It is explanatory sectional drawing which shows a part of liquid crystal display device of a 1st comparative example. It is an explanatory top view which shows a part of array substrate of a liquid crystal display device same as the above. It is an explanatory top view which shows a part of counter substrate of a liquid crystal display device same as the above. It is a graph which shows CR viewing angle of a liquid crystal display device same as the above. It is explanatory sectional drawing which shows a part of liquid crystal display device of a 2nd comparative example. It is an explanatory top view which shows a part of counter substrate of a liquid crystal display device same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal cell as a liquid crystal display device 2 Array substrate 3 Glass substrate as translucent substrate 5 Pixel
13 Auxiliary capacity line as capacity line
21 Reflective display area as reflective area
22 Transparent display area as transparent area
31 Counter substrate
32 Glass substrate as translucent substrate
35 Insulation layer
42 Liquid crystal layer

Claims (6)

Translucent substrate, a plurality of pixels provided in a matrix on one main surface of the translucent substrate, a reflective region provided in the plurality of pixels and visible by light reflection, and sandwiching these reflective regions An array substrate provided with a transmissive region provided on both sides of the reflective region and visible by light transmission;
The translucent substrate disposed opposite to the one main surface of the translucent substrate of the array substrate, and the one main surface of the array substrate on the side facing the one main surface of the array substrate A counter substrate including an insulating layer provided to face at least a part of each of the transmission region and the reflection region of the plurality of pixels;
A liquid crystal display device comprising: a liquid crystal layer interposed between the array substrate and the counter substrate. The liquid crystal display device according to claim 1, wherein the insulating layer is formed in an uneven shape. Each of the plurality of pixels is provided in a long shape,
The reflective region is provided in the center in the longitudinal direction of the pixel,
The liquid crystal display device according to claim 1, wherein the transmissive region is provided on both sides of the reflective region along the longitudinal direction. The liquid crystal display device according to any one of claims 1 to 3, wherein the reflection region and the transmission region are formed such that a voltage applied to the reflection region and the transmission region is equal to a luminance. The array substrate includes a capacitance line provided on one main surface of the translucent substrate,
The liquid crystal display device according to claim 1, wherein the insulating layer is provided at a position facing the capacitor line. 6. The insulating layer according to claim 1, wherein a portion of the insulating layer facing the reflective region and a portion facing the transmitting region are provided in the same material and in the same process. Liquid crystal display device.

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