JP2008157997A - Liquid crystal device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal device which has a liquid crystal made thin and improved in manufacturing efficiency, decreases alignment defects of liquid crystal by preventing a beltlike electrode formed in a reflective display area from being broken or short-circuited, and prevents display quality from decreasing, and electronic equipment. <P>SOLUTION: The liquid crystal device has an element substrate 21 provided with a plurality of pixel areas S each having a reflective display area R and a counter substrate 22, a liquid crystal layer 23 held between the element substrate 21 and the counter substrate 22 which face each other, an inter-layer insulating layer 33 which is provided in the reflective display area R on the element substrate 21 and has an uneven surface 33A, a reflecting layer 44 which is provided on the inter-layer insulating layer 33 and has an uneven portion 44a corresponding to the uneven surface 33A, and a pixel electrode 11 and a common electrode 45 which are provided above the reflecting layer 44 and apply a voltage to the liquid crystal layer 23, a flattened layer 34 being provided between the reflecting layer 44 and pixel electrode 11, and the common electrode 45. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal device and an electronic apparatus.

  2. Description of the Related Art Conventionally, transflective liquid crystal devices have been used in which external light is used in bright places and display is visible using an internal light source such as a backlight in dark places. This transflective liquid crystal device employs a display system that has both a reflective type and a transmissive type. By switching to either the reflective mode or the transmissive mode depending on the ambient brightness, It is designed to enable clear display even when the surroundings are dark while reducing power.

  By the way, in such a transflective liquid crystal device, a transmissive display for performing transflective display and a reflective display region for performing reflective display are provided in one pixel region. A reflective layer that reflects external light incident on the liquid crystal layer toward the incident surface is provided in a region corresponding to the reflective display region of the liquid crystal device. The surface of the reflective layer is provided with irregularities for reflecting light while scattering for the purpose of obtaining good display characteristics in reflective display.

  Further, as one means for achieving a wide viewing angle of the liquid crystal device, it is known to use a method of controlling the alignment of liquid crystal molecules by generating an electric field in the substrate direction with respect to the liquid crystal layer (hereinafter referred to as a transverse electric field method). As such a horizontal electric field method, an IPS (In-Plane Switching) method and an FFS (Fringe-Field Switching) method are known. In a liquid crystal device using such a horizontal electric field method, a pixel electrode and a common electrode, which are a pair of electrodes for driving liquid crystal molecules, are provided on one of a pair of substrates that sandwich a liquid crystal layer. For example, a pixel electrode in an FFS mode liquid crystal device includes a plurality of band-like electrodes provided at intervals in order to generate an electric field with the common electrode.

In a liquid crystal device using a transflective FFS method, a pixel electrode in a reflective display region may be provided on an uneven surface corresponding to the reflective display region. Since the strip electrode (comb-like electrode) is formed on the uneven surface, it is difficult to finely process the strip electrode, and the strip electrode may be disconnected or short-circuited with another adjacent strip electrode. In addition, since the pixel electrode is directly formed on the uneven surface, the pixel electrode is formed in an uneven shape. Then, when a voltage is applied, the electric field may be disturbed and the liquid crystal may not be aligned in a desired direction. A structure is disclosed in which planarization is performed with a color filter and an overcoat, and electrodes are formed thereon (see Patent Documents 1 and 2).
JP 2002-258262 A Japanese Patent No. 3733923

  However, in the said patent document, the problem at the time of forming an electrode on the reflective layer which has an uneven | corrugated | grooved part is not considered.

  The present invention has been made in view of the above-described problems, and its object is to reduce the thickness of the liquid crystal device and improve the manufacturing efficiency, and to prevent the disconnection and short circuit of the electrodes formed in the reflective display region. It is an object of the present invention to provide a liquid crystal device and an electronic apparatus that can reduce alignment defects and prevent deterioration of display quality.

  In order to solve the above problems, a liquid crystal device according to the present invention includes a pair of substrates provided with a plurality of pixel regions having a reflective display region, a liquid crystal layer sandwiched between a pair of substrates facing each other, and a pair of substrates. Provided in the reflective display area of one of the substrates, a base layer having an uneven surface, a reflective layer provided on the base layer and having an uneven portion corresponding to the uneven surface, and provided above the reflective layer A first electrode and a second electrode for applying a voltage to the liquid crystal layer, and a planarizing layer is provided between the reflective layer and the first electrode and the second electrode. Liquid crystal device.

  In the conventional liquid crystal device having a reflective display area, the unevenness of the reflective layer is reflected in the electrode shape, whereas according to the liquid crystal device of the present invention, the level difference of the uneven portion of the reflective layer is a flattened layer. Therefore, the surface of the reflective layer, that is, the surface of the flattened layer can be made a substantially flat surface. By forming the first electrode and the second electrode above the flattening layer having such a flat surface, the disturbance of the electric field for driving the liquid crystal layer can be reduced, as will be described in Examples described later. it can. As described above, since the uneven portion of the reflective layer is prevented from being reflected in the shapes of the first electrode and the second electrode by using the planarizing layer, the disorder of the alignment direction of the liquid crystal is improved, and the alignment of the liquid crystal is improved. Degradation of display characteristics due to defects can be avoided. In addition, since the first electrode and the second electrode can be formed on a flat surface, no disconnection or short circuit occurs during patterning, and the yield is improved.

Moreover, it is also preferable that the first electrode and the second electrode are provided on the planarization layer.
According to such a structure, it can prevent that the uneven | corrugated | grooved part of a reflection layer is reflected in the shape of a 2nd electrode by providing a 1st electrode and a 2nd electrode on a planarization layer. Therefore, the liquid crystal can be driven in a good alignment state.

  The liquid crystal device according to the present invention includes a pair of substrates provided with a plurality of pixel regions having a reflective display region, a liquid crystal layer sandwiched between a pair of substrates facing each other, and one of the pair of substrates. A first electrode comprising a base layer having a concavo-convex surface provided in the reflective display area, a reflective layer having a concavo-convex portion corresponding to the concavo-convex surface provided on the base layer, and provided above the first electrode; And a second electrode for applying a voltage to the liquid crystal layer between the first electrode and a planarizing layer provided between the first electrode and the second electrode. .

Further, according to the liquid crystal device of the present invention, since the reflective layer functions as the first electrode in the present invention, the number of work steps can be reduced, the cost can be reduced, and the entire device can be thinned.
In addition, since the level difference of the concavo-convex portion of the reflective layer is flattened by the flattening layer, the surface of the first electrode made of the reflective layer, that is, the surface of the flattened layer can be made substantially flat. By forming the second electrode above the planarizing layer having such a flat surface, it is possible to reduce the disturbance of the electric field that drives the liquid crystal layer, as will be described in Examples described later. As described above, since the uneven portion of the reflective layer is prevented from being reflected in the shape of the second electrode by using the flattening layer, the disorder of the alignment direction of the liquid crystal is improved, resulting from the poor alignment of the liquid crystal. Degradation of display characteristics can be avoided. In addition, since the second electrode can be formed on a flat surface, no disconnection or short circuit occurs during patterning, thereby improving yield.

It is also preferable that the second electrode is provided above the first electrode through a dielectric layer made of a planarizing layer.
According to such a configuration, it is possible to easily realize a liquid crystal device in which the FFS mode electrode arrangement is adopted by the arrangement of the first electrode and the second electrode. When such an FFS electrode arrangement is employed, the liquid crystal positioned above the electrode can also be driven. In addition, since the second electrode is provided on the dielectric layer made of the planarizing layer, it is possible to prevent the uneven portion of the reflective layer from being reflected in the shape of the second electrode. Therefore, the liquid crystal positioned on the second electrode can be driven in a good alignment state.

The pixel region is provided with a transmissive display region in which the reflective layer is not formed, and a third electrode that applies a voltage to the liquid crystal layer between the second electrode and the transmissive display region. The first electrode and the third electrode are provided in the same layer and are electrically connected to each other, and the second electrode is connected to the first electrode via a dielectric layer made of the planarizing layer. It is also preferable to be provided above the electrode and the third electrode.
According to such a configuration, the first electrode (reflective layer) provided in the reflective display region and the third electrode provided in the transmissive display region are provided in the same layer and are electrically connected to each other. The liquid crystal positioned above the second electrode can be driven without increasing the number of stacked layers on the substrate. In addition, by the first electrode and the third electrode having the above-described configuration, a uniform voltage is applied to the liquid crystal layer in the reflective display region and the transmissive display region between the second electrode provided across the reflective display region and the transmissive display region. Can be applied. Therefore, the liquid crystal can be driven in a good alignment state.

It is also preferable that the second electrode is provided above the first electrode via the dielectric layer and has a plurality of electrode fingers.
According to such a configuration, the second electrode formed on the reflective layer via the planarization layer on the liquid crystal layer side than the first electrode and the third electrode has a plurality of electrode fingers. By arranging the first electrode, the second electrode, and the third electrode, it is possible to easily realize a liquid crystal device that employs an FFS electrode arrangement. When such an FFS-type electrode arrangement is employed, the liquid crystal positioned above the electrodes can be driven satisfactorily.

The pixel region is provided with an electrode non-formation region in which the second electrode is not formed, and the planarization layer has a film thickness in a portion overlapping the electrode non-formation region and a film in a portion overlapping the second electrode. It is also preferable that the thickness is smaller than the thickness.
According to such a configuration, even when the planarization layer becomes thick in the manufacturing process, the thickness of the portion (electrode non-formation region) corresponding to the gap between the electrode fingers of the second electrode is set to the second electrode. The thickness of the planarization layer can be partially reduced by forming the film thinner than the film thickness of the portion where the film is formed. Thereby, an electric field can be generated between the first electrode and the second electrode at a low voltage. Here, since the area | region where the 1st and 2nd electrode is formed in the surface of the planarization layer should just be flat, the method of thinning is not ask | required.

  The liquid crystal device according to the present invention includes a pair of substrates provided with a plurality of pixel regions having a reflective display region, a liquid crystal layer sandwiched between a pair of substrates facing each other, and one of the pair of substrates. A base layer having an uneven surface provided in the reflective display region, a reflective layer having an uneven portion corresponding to the uneven surface provided on the base layer, and a plurality of strip electrode portions provided above the reflective layer And an electrode for applying a voltage to the liquid crystal layer, and a planarization layer is provided between the reflective layer and the electrode.

  According to the liquid crystal device of the present invention, since the plurality of strip electrode portions are provided above the reflective layer via the flattening layer, it is possible to easily realize a liquid crystal device that employs an IPS electrode arrangement. it can. When such an IPS electrode arrangement is adopted, the liquid crystal positioned above the electrode can be driven well.

An electronic apparatus according to the present invention includes the liquid crystal device as described above.
According to the electronic apparatus of the present invention, since it is configured to include the liquid crystal device that can prevent the electric field from being disturbed by the uneven portion of the reflective film, high-quality display can be achieved.

[First Embodiment]
Hereinafter, a liquid crystal device according to a first embodiment of the invention will be described with reference to the drawings. In each drawing used in the following description, the scale is appropriately changed to make each member a recognizable size. Here, FIG. 1 is an equivalent circuit diagram showing a liquid crystal device, FIG. 2 is a plan view of a sub-pixel region, FIG. 3 is a cross-sectional view taken along line AA in FIG. 2, and FIG. FIG. FIG. 4 is a cross-sectional view showing a schematic configuration of the liquid crystal device, and some components are omitted.

[Liquid crystal device]
The liquid crystal device 1 in the present embodiment is a color liquid crystal device, and one pixel is constituted by three sub-pixel regions that emit light of each color of R (red), G (green), and B (blue). It is a liquid crystal device. Hereinafter, the pixel area which is the minimum unit constituting the display is referred to as a “sub-pixel area”.

  First, a schematic configuration of the liquid crystal device 1 will be described. As shown in FIG. 1, the liquid crystal device 1 has a plurality of sub-pixel areas constituting an image display area arranged in a matrix. In each of the plurality of sub-pixel regions, a pixel electrode 11 and a TFT (Thin Film Transistor) element (drive element) 12 for switching control of the pixel electrode 11 are formed. The TFT element 12 has a source electrode electrically connected to a data line 14 extending from a data line driving circuit 13 provided in the liquid crystal device 1, and a gate from a scanning line driving circuit 15 provided in the liquid crystal device 1. The drain scanning electrode 16 is electrically connected to the extending scanning line 16, and the drain electrode is electrically connected to the pixel electrode 11.

  The data line driving circuit 13 is configured to supply image signals S1, S2,..., Sn to the sub-pixel regions via the data line. Here, the data line driving circuit 13 may supply the image signals S1 to Sn line-sequentially in this order, or may supply each of the data lines 14 adjacent to each other for each group.

  The scanning line driving circuit 15 is configured to supply scanning signals G1, G2,..., Gm to the sub-pixel regions via the scanning lines 16. Here, the scanning line drive circuit 15 supplies the scanning signals G1 to Gm in a pulse-sequential manner at predetermined timing.

  Further, in the liquid crystal device 1, the TFT elements 12 that are switching elements are turned on for a certain period by the input of the scanning signals G <b> 1 to Gm, so that the image signals S <b> 1 to Sn supplied from the data line 14 have a predetermined timing. Thus, the pixel electrode 11 is written. A predetermined level of image signals S1 to Sn written to the liquid crystal via the pixel electrode 11 is held for a certain period between the pixel electrode 11 and a common electrode 45 described later.

Next, a detailed configuration of the liquid crystal device 1 will be described with reference to FIGS. In FIG. 2, the counter substrate is not shown. In FIG. 2, the major axis direction of the sub-pixel region S that is substantially rectangular in plan view is defined as the X-axis direction, and the minor axis direction is defined as the Y-axis direction.
As shown in FIGS. 2 and 3, the liquid crystal device 1 has one end portion in the major axis direction (X-axis direction) of the sub-pixel region S (two in the major-axis direction of the sub-pixel region S). Of the divided areas, two display areas in which the area corresponding to the sub-pixel area S and the side away from the scanning line 16) is the reflective display area R and the other area is the transmissive display area T. have.

As shown in FIG. 3, the liquid crystal device 1 includes an element substrate (substrate) 21, a counter substrate 22 disposed to face the element substrate 21, and a liquid crystal layer 23 sandwiched between the element substrate 21 and the counter substrate 22. The polarizing plate 24 provided on the outer surface side of the element substrate 21 (the side opposite to the liquid crystal layer 23) and the polarizing plate 25 provided on the outer surface side of the counter substrate 22 are provided. The liquid crystal device 1 is configured to be irradiated with illumination light from the outer surface side of the element substrate 21.
The liquid crystal device 1 is provided with a sealing material (not shown) along the edge of the region where the element substrate 21 and the counter substrate 22 face each other. The liquid crystal layer 23 is sealed.

  The element substrate 21 includes, for example, a substrate body 31 made of a light-transmitting material such as glass, quartz, and plastic, a gate insulating film 32 and an interlayer insulating layer sequentially stacked on the inner surface (the liquid crystal layer 23 side) of the substrate body 31. 33 (underlying layer) and an alignment film 36 are provided.

  The element substrate 21 includes a scanning line 16 disposed on the inner surface of the substrate body 31, a data line 14 (shown in FIG. 2) disposed on the inner surface of the gate insulating film 32, a semiconductor layer 41, a source The electrode 43 and the drain electrode 42, the reflective layer 44 disposed on the inner surface of the interlayer insulating layer 33, the planarizing layer 34 disposed on the inner surface of the interlayer insulating layer 33 and the reflective layer 44, and the planarizing layer 34, a common electrode 45 disposed on the inner surface of the common electrode 45, a dielectric layer 35 disposed on the inner surface of the common electrode 45, and a pixel electrode 11 disposed on the inner surface of the dielectric layer 35.

  As shown in FIG. 2, the data line 14 is arranged along the long axis direction (X-axis direction) of the rectangular sub-pixel region S in plan view. The scanning lines 16 are arranged along the minor axis direction (Y-axis direction) of the sub-pixel region S. Therefore, the data lines 14 and the scanning lines 16 are wired in a substantially lattice shape in plan view.

  The gate insulating film 32 shown in FIG. 3 is made of a translucent material such as SiO 2 (silicon oxide), for example, and is provided so as to cover the scanning lines 16 formed on the substrate body 31.

  As shown in FIGS. 2 and 3, the semiconductor layer 41 is partially formed in a region overlapping the scanning line 16 through the gate insulating film 32 in plan view, and is made of a semiconductor such as amorphous silicon or polysilicon. Yes. The source electrode 43 is branched from the data line 14 and is formed so as to partially cover the semiconductor layer 41. The drain electrode 42 is formed so as to partially cover the semiconductor layer 41, and is electrically connected to the pixel electrode 11 through the contact hole H penetrating the interlayer insulating layer 33 and the planarization layer 34. Yes. The TFT layer 12 is configured by the semiconductor layer 41, the drain electrode 42, and the source electrode 43. The TFT element 12 is provided in the vicinity of the intersection of the data line 14 and the scanning line 16 as shown in FIG.

  Like the gate insulating film 32, the interlayer insulating layer 33 is made of a light-transmitting material such as SiN (silicon nitride), for example, and the data formed on the gate insulating film 32 as shown in FIGS. It is provided on the surface of the gate insulating film 32 so as to cover the line 14, the semiconductor layer 41, the source electrode 43 and the drain electrode 42.

As shown in FIG. 4, the inner surface corresponding to the reflective display region R has an uneven shape, and has a plurality of convex portions 33a formed dispersed on the inner surface. The plurality of convex portions 33 a are formed by patterning the interlayer insulating layer 33. In this way, by providing a configuration in which a plurality of convex portions 33 a are arranged, the concave and convex surface 33 </ b> A is formed on the inner surface of the interlayer insulating layer 33.

  The reflective layer 44 is formed by patterning a light-reflective metal film such as aluminum, APC, or silver. The reflective layer 44 is an inner surface of the interlayer insulating layer 33 corresponding to the reflective display region R, that is, a convex portion 33a (concave / convex portion). Surface 33A). As a result, the reflective layer 44 has a concavo-convex portion 44a having a concavo-convex surface 44A corresponding to the concavo-convex surface 33A on the surface of the interlayer insulating layer 33, and is configured to perform scattering reflection. The shape of the concavo-convex portion 44a is such that the in-plane pitch of the concavo-convex is within a predetermined range and the height of the concavo-convex is 0.5 to, for example, so that light is efficiently scattered and reflected and the flatness of the substrate is not deteriorated. It is set so as to be within the range of 1.0 μm.

  As shown in FIGS. 3 and 4, the planarization layer 34 is made of a light-transmitting material such as a low-viscosity negative resist or a UV curable resin, and embeds a step in the uneven portion 44 a of the reflective layer 44. Thus, the interlayer insulating layer 33 and the reflective layer 44 are covered. At this time, if the planarizing layer 34 is formed using a material having a high viscosity, the shape of the concavo-convex portion 44 a of the reflective layer 44 is reflected. This impairs the flatness of the inner surface of the flattening layer 34 in the reflective display region R. Therefore, the flattening layer 34 is adjusted in viscosity according to the level difference of the concavo-convex portion 44a of the reflective layer 44 so that the inner surface of the reflective display region R has the same flatness as the inner surface on the transmissive display region T side. It is important to do.

  Further, in the interlayer insulating layer 33 and the planarizing layer 34, a contact hole H penetrating the interlayer insulating layer 33 and the planarizing layer 34 is formed in a region overlapping the drain electrode 42 in plan view.

As shown in FIGS. 2 and 3, the common electrode 45 is formed so as to cover the planarization layer 34 and the reflection layer 44, and is made of a light-transmitting conductive material such as ITO (indium tin oxide). Yes.
Since the inner surface of the flattening layer 34 is a flat surface in both the reflective display region R and the transmissive display region T, the inner surface of the common electrode 45 has the same flat surface regardless of the region. . For example, a predetermined constant voltage or 0 V used for driving the liquid crystal layer 23, or a predetermined constant potential and another predetermined constant potential different from the common electrode 45 are periodically (every frame period or A signal that changes every field period) is applied.

  The dielectric layer 35 is formed so as to cover the common electrode 45, and is composed of a transparent material such as silicon oxide (SiO2) in the case of an inorganic material, and a transparent material such as an acrylic resin in the case of an organic material. The The common electrode 45 and the pixel electrode 11 are insulated from each other by interposing the dielectric layer 35 between the common electrode 45 and the pixel electrode 11. Also in this dielectric layer 35, the inner surface is a flat surface regardless of the region.

  The pixel electrode 11 is formed on the dielectric layer 35 and has a substantially ladder shape in a plan view as shown in FIG. 2. Like the common electrode 45, the pixel electrode 11 is made of a translucent conductive material such as ITO. It is configured. The pixel electrode 11 extends in the short axis direction (Y-axis direction) of the sub-pixel region S and the long-axis direction (X-axis) of the sub-pixel region S, and extends substantially in the short-axis direction (Y-axis direction) of the sub-pixel region S. A plurality of (15) strip-like portions 11b (electrode fingers) arranged at intervals in the direction). Since such a pixel electrode 11 is disposed on the dielectric layer 35 having a flat inner surface as shown in FIG. 3, the pixel electrode 11 is not affected by the shape of the uneven portion 44a of the reflective layer 44. It has a configuration.

As shown in FIG. 2, the frame portion 11 a has a configuration in which two pairs of strip electrodes along the data line 14 and the scanning line 16 are connected to form a substantially rectangular frame shape in plan view. Two pairs of opposing sides extend along the X-axis direction and the Y-axis direction, respectively.
The strip portions 11b are formed so as to be parallel to each other, and both ends thereof are connected to portions of the frame portion 11a extending along the Y-axis direction. Moreover, the strip | belt-shaped part 11b is provided so that the extension direction may become non-parallel to the Y-axis direction. That is, the strip portion 11b is formed so that its extending direction is closer to the scanning line 16 as it goes from one end away from the data line 14 toward the other end in plan view.

  The alignment film 36 is made of, for example, a resin material such as polyimide, and is provided so as to cover the pixel electrode 11 formed on the dielectric layer 35 shown in FIG. The surface of the alignment film 36 is subjected to an alignment process in which the short axis direction (Y-axis direction) of the sub-pixel region S shown in FIG.

  As described above, the liquid crystal device 1 has a configuration in which a voltage is applied between the strip portion 11b and the common electrode 45, and the liquid crystal is driven by an electric field (lateral electric field) generated in the direction of the substrate plane. Accordingly, the pixel electrode 11 and the common electrode 45 constitute an FFS type electrode structure.

  On the other hand, as shown in FIG. 3, the counter substrate 22 is sequentially formed on a substrate body 51 made of a translucent material such as glass, quartz, and plastic, and on the inner surface (the liquid crystal layer 23 side) of the substrate body 51. A light shielding film 52, a color filter layer 53, an alignment film 54b, a retardation layer 55, and an alignment film 54a are provided.

The light shielding film 52 is formed in a region of the surface of the substrate body 51 that overlaps the edge of the sub pixel region S in plan view, and borders the sub pixel region S.
The color filter layer 53 is disposed corresponding to each sub-pixel region S, and is made of, for example, acrylic and contains a color material corresponding to the color displayed in each sub-pixel region S.

  The retardation layer 55 is provided on the reflective display region R side on the color filter layer 53. By providing the retardation layer 55 in the reflective display region R, appropriate reflective display and transmissive display can be obtained. By incorporating the retardation layer 55 in the liquid crystal cell, it is not necessary to provide a retardation plate or the like for adjusting the retardation outside the liquid crystal cell, and the liquid crystal cell can be made thinner and less expensive.

  Further, the alignment film 54 a is made of a light-transmitting resin material such as polyimide, and is provided so as to cover the color filter layer 53 and the retardation layer 55. The alignment film 54 b provided on the substrate body 51 side of the retardation layer 55 is provided for the alignment of the retardation layer 55. The inner surface of the alignment film 54a is rubbed in the same direction as the alignment direction of the alignment film 36, and the alignment film 54b is subjected to an alignment process corresponding to the desired slow axis. Has been.

  Since the liquid crystal molecules constituting the liquid crystal layer 23 are subjected to an alignment process in which the alignment direction is the short axis direction (Y-axis direction) of the sub-pixel region S on the alignment films 36 and 54 a, the pixel electrode 11 and the common electrode 45. In a state where no voltage is applied (OFF state) during the period, the film is horizontally oriented along the Y-axis direction shown in FIG. Further, the liquid crystal molecules are aligned along a direction orthogonal to the extending direction of the belt-like portion 11b in a state where a voltage is applied between the pixel electrode 11 and the common electrode 45 (on state). Therefore, in the liquid crystal layer 23, a phase difference is given to the light transmitted through the liquid crystal layer 23 by utilizing birefringence based on the difference in the alignment state of the liquid crystal molecules between the off state and the on state.

  The polarizing plate 24 is provided so that its transmission axis is along the major axis direction (X-axis direction shown in FIG. 2) of the sub-pixel region S. The polarizing plate 25 has a transmission axis shorter than that of the sub-pixel region S. It is provided along the axial direction (Y-axis direction shown in FIG. 2). Accordingly, the polarizing plates 24 and 25 are provided so that their transmission axes are substantially orthogonal to each other.

  Here, an optical compensation film (not shown) may be disposed inside one or both of the polarizing plates 24 and 25. By disposing the optical compensation film, it is possible to compensate for the phase difference of the liquid crystal layer 23 when the liquid crystal device 1 is perspective, and to reduce light leakage and increase contrast.

[Method of manufacturing liquid crystal device]
Next, a manufacturing method of the liquid crystal device 1 having such a configuration will be described with reference to FIGS. First, similarly to the conventional method of manufacturing a liquid crystal device, the scanning line 16 is formed on the substrate body 31, and the gate insulating film 32 is formed so as to cover it. Then, the data line 14, the semiconductor layer 41, the source electrode 43, and the drain electrode 42 are formed on the gate insulating film 32, and the interlayer insulating layer 33 is formed so as to cover them.

And the uneven surface 33A which consists of several convex part 33a is formed in the area | region corresponding to the reflective display area | region R among the inner surfaces of the interlayer insulation layer 33 (uneven | corrugated shape provision process). Here, for example, a positive photosensitive acrylic resin is applied on the interlayer insulating layer 33 to form a resin layer (not shown). Then, exposure light is irradiated using a mask having a predetermined opening pattern. Here, the opening pattern of the mask has a shape in which exposure light is irradiated to a region corresponding to the non-formation region of the convex portion 33a and the transmissive display region T.
The interlayer insulating layer 33 and the convex portion 33a may be integrally formed.

  Thereafter, the exposed area of the resin layer is removed with a developer. Thereby, a substantially columnar protrusion is formed. Further, the heat treatment is performed on the resin layer, so that the upper end surface of the protruding portion is softened to form the convex portion 33a. In this way, the interlayer insulating layer 33 is formed in which the inner surface in the reflective display region R is the uneven surface 33A.

  Subsequently, a reflective layer 44 is formed on the interlayer insulating layer 33 (reflective layer forming step). A metal film is formed on the interlayer insulating layer 33, and the transmissive display region T side is patterned using a known photolithography technique. In this way, the reflective layer 44 having the concavo-convex portion 44a corresponding to the convex portion 33a is formed on the reflective display region R side where the convex portion 33a is formed in the interlayer insulating layer 33.

  Then, a planarizing layer 34 is formed on the interlayer insulating layer 33 and the reflective layer 44 (planarizing layer forming step). At this time, the reflective display region R and the transmissive display region T are formed in such a film thickness that has the same flatness so as to bury the step of the uneven portion 44a of the reflective layer 44. Thereby, the inner surface of the planarization layer 34 becomes a flat surface having the same flatness in both the reflective display region R and the transmissive display region T.

Next, the common electrode 45 is formed on the planarizing layer 34 (electrode forming step), and the dielectric layer 35 is formed so as to cover it. Further, a contact hole H penetrating the interlayer insulating layer 33 and the planarizing layer 34 is formed, and the pixel electrode 11 is formed on the dielectric layer 35. Here, since the flatness of the inner surface of the common electrode 45 and the dielectric layer 35 is improved by providing the flattening layer 34 on the reflective layer 44, the frame portion 11a and the strip-shaped portion 11b are disconnected. The pattern is formed without short-circuiting with the adjacent belt-like portion 11b. That is, the configuration is such that the influence of the shape of the uneven portion 44 a of the reflective layer 44 does not reach the formation of the pixel electrode 11.
Thereafter, an alignment film 36 is formed so as to cover it. As described above, the element substrate 21 is formed.

A light shielding film 52 and a color filter layer 53 are formed on the substrate body 51. Then, the retardation layer 55 is formed on the alignment film 54 b on the reflective display region R side on the color filter layer 53, and the alignment film 54 a is formed so as to cover the retardation layer 55 and the color filter layer 53. As described above, the counter substrate 22 is formed.
Thereafter, the element substrate 21 and the counter substrate 22 formed as described above are bonded together with a sealing material, and liquid crystal is injected and sealed, thereby forming the liquid crystal layer 23. Then, polarizing plates 24 and 25 are disposed on the outer surfaces of the element substrate 21 and the counter substrate 22, respectively. The liquid crystal device 1 is manufactured as described above.

[Operation of liquid crystal device]
Next, the operation of the liquid crystal device 1 having such a configuration will be described.
First, transmissive display (transmission mode) will be described. Light incident on the transmissive display region T from the outer surface side of the element substrate 21 is converted by the polarizing plate 24 into linearly polarized light parallel to the major axis direction (X-axis direction shown in FIG. 2) of the sub-pixel region S, and the liquid crystal layer 23. Is incident on.
Here, in the off state, the linearly polarized light incident on the liquid crystal layer 23 is emitted from the liquid crystal layer 23 in the same polarization state as that upon incidence by the liquid crystal layer 23. The linearly polarized light has its polarization direction orthogonal to the transmission axis of the polarizing plate 25, and is thus blocked by the polarizing plate 25, and the sub-pixel region S is darkly displayed.

  On the other hand, in the case of the on state, the linearly polarized light incident on the liquid crystal layer 23 is converted into linearly polarized light orthogonal to the polarization direction at the time of incidence and is emitted from the liquid crystal layer 23. Since the polarization direction of the linearly polarized light is parallel to the transmission axis of the polarizing plate 25, the linearly polarized light passes through the polarizing plate 25 and is visually recognized as display light, and the sub-pixel region S is brightly displayed.

Subsequently, reflection display (reflection mode) will be described. Light incident from the outer surface side of the counter substrate 22 is converted into linearly polarized light parallel to the minor axis direction of the sub-pixel region S (Y-axis direction shown in FIG. 2) by the polarizing plate 25 and is incident on the liquid crystal layer 23.
Here, in the off state, the linearly polarized light incident on the liquid crystal layer 23 is converted into circularly polarized light and reaches the reflective layer 44.

When this circularly polarized light is reflected by the reflective layer 44, the rotation direction is reversed. Thereafter, the circularly polarized light is converted into linearly polarized light orthogonal to the polarization direction at the time of incidence by the liquid crystal layer 23 and is emitted from the liquid crystal layer 23. The linearly polarized light has its polarization direction orthogonal to the transmission axis of the polarizing plate 25, and is thus blocked by the polarizing plate 25, and the sub-pixel region S is darkly displayed.

  On the other hand, in the case of the ON state, the linearly polarized light incident on the liquid crystal layer 23 reaches the reflective layer 44 in the same polarization state as that upon incidence by the liquid crystal layer 23. The linearly polarized light reflected by the reflective layer 44 is emitted from the liquid crystal layer 23 in the same polarization direction as that at the time of incidence. Thereafter, since the polarization direction of the linearly polarized light is parallel to the transmission axis of the polarizing plate 25, the linearly polarized light is transmitted through the polarizing plate 25 and visually recognized as display light, and the sub-pixel region S is brightly displayed.

  Here, the light incident on the concavo-convex portion 44 a of the reflective layer 44 is scattered and reflected and reenters the liquid crystal layer 23 because the inner surface of the reflective layer 44 is the concavo-convex surface 44 </ b> A. Thereby, regular reflection of external light in the on state is prevented, and a reflective display with excellent visibility is obtained.

  In the liquid crystal device 1 of the present embodiment, the planarization layer 34 is embedded in the step of the concavo-convex portion 44 a of the reflective layer 44 so that the inner surface of the common electrode 45 and the inner surface of the dielectric layer 35 are flat. By forming the inner surface of the flattening layer 34 as a flat surface, the formation surface (the inner surface of the dielectric layer 35) of the strip 11b of the pixel electrode 11 in a region overlapping the reflective layer 44 (uneven portion 44a) in a plan view is flat. It becomes a surface. Thereby, since patterning of the frame part 11a and the some strip | belt-shaped part 11b can be performed with a sufficient precision, the disconnection of the frame part 11a and the strip | belt-shaped part 11b, the short circuit with the adjacent other strip-shaped part 11b, etc. can be prevented. Moreover, it is possible to suppress the occurrence of disturbance due to the uneven shape in the electric field generated between the common electrode 45 and the band-like portion 11b of the pixel electrode 11 in the reflective display region R, and display characteristics similar to those of the transmissive display region T are obtained. be able to. That is, by improving the conventional electric field disturbance in the reflective display region R, as in the transmissive display region T, the major axis direction of the liquid crystal molecules positioned on the pixel electrode 11 is in a state where a voltage is applied to the pixel electrode 11. It is systematically oriented in a direction perpendicular to the extending direction of the belt-like portion 11b.

[Second Embodiment]
Next, a liquid crystal device according to a second embodiment of the invention will be described with reference to the drawings. Here, FIG. 5 is a cross-sectional view showing a sub-pixel region of the liquid crystal device in the second embodiment. In this embodiment, since the configuration of the sub-pixel region of the first embodiment is different, this point will be mainly described, and the components described in the first embodiment are denoted by the same reference numerals, Description is omitted.

  In the liquid crystal device 60 according to the present embodiment, as shown in FIG. 5, a reflective layer 44 and a common electrode 45 made of a conductive material such as aluminum, APC, or silver are formed, and the reflective layer 44 and the common electrode 45 are formed. It is configured to conduct.

  Specifically, on the element substrate 21 side, the reflective layer 44 is provided on the convex portion 33a (uneven surface 33A) of the interlayer insulating layer 33 in the reflective display region R as in the above embodiment. The common electrode 45 in this embodiment is not provided so as to cover the reflective layer 44 as in the first embodiment, but most of the common electrode 45 covers the interlayer insulating layer 33 exposed in the transmissive display region T. Is provided. Here, the common electrode 45 is laminated only on the end portion of the reflective layer 44 corresponding to the boundary between the reflective display region R and the transmissive display region T, and the reflective layer 44 is electrically connected to the common electrode 45. .

  Then, the dielectric layer 35 is laminated on the reflective layer 44 and the common electrode 45, and is provided so as to fill the step of the uneven portion 44a of the reflective layer 44. The dielectric layer 35 has only to have a film thickness that allows the inner surface thereof to be a flat surface, and has a viscosity that does not reflect the shape of the uneven portion 44 a of the reflective layer 44. However, if the thickness of the dielectric layer 35 is too thick, it is difficult to apply an electric field.

  The pixel electrode 11 is formed on such a dielectric layer 35. Since the inner surface is a flat surface, patterning of the pixel electrode 11 can be performed with high accuracy, so that the disconnection of the frame portion 11a and the strip portion 11b and the short circuit with the other adjacent strip portion 11b can be prevented. Further, it is possible to suppress the occurrence of disturbance in the electric field generated between the common electrode 45 in the reflective display region R and the strip 11b of the pixel electrode 11, and the reflective display region R has the same display characteristics as the transmissive display region T. Obtainable. Thus, as in the first embodiment, the disturbance of the electric field in the reflective display region R is improved, so that the major axis direction of the liquid crystal molecules located on the pixel electrode 11 is in the voltage application state as in the transmissive display region T. Thus, they are systematically oriented in the direction orthogonal to the extending direction of the strip 11b of the pixel electrode 11.

In this embodiment, since the reflective layer 44 and the common electrode 45 are electrically connected, the reflective layer 44 functions as the common electrode 45. If the reflective layer 44 and the common electrode 45 are covered with the dielectric layer 35, the step of the concavo-convex portion 44a can be filled, and the reflective layer 44 and the common electrode 45 that perform the electrode function, and the pixel electrode 11 can be filled. Therefore, it is not necessary to separately form the planarizing layer 34 provided in the first embodiment. As a result, the number of manufacturing steps can be reduced and the manufacturing efficiency can be improved, and the liquid crystal cell can be thinned and the cost can be reduced accordingly. If the reflective layer 44 and the common electrode 45 are electrically connected, the common electrode 45 may not be directly laminated on the reflective layer 44.

[Third Embodiment]
Next, a liquid crystal device according to a third embodiment of the present invention will be described with reference to the drawings. Here, FIG. 6 is a cross-sectional view showing a sub-pixel region of the liquid crystal device according to the third embodiment. In this embodiment, since the configuration of the sub-pixel region of the first embodiment is different, this point will be mainly described, and the components described in the first embodiment are denoted by the same reference numerals, Description is omitted.

  In the liquid crystal device 60 according to the present embodiment, as shown in FIG. 6, the non-formation region of the pixel electrode 11 on the surface of the dielectric layer 35 is etched, and the thickness of the dielectric layer 35 is partially reduced. Yes.

  Specifically, on the element substrate 21 side, the reflective layer 44 is provided on the convex portion 33a (uneven surface 33A) of the interlayer insulating layer 33 in the reflective display region R as in the first embodiment. A common electrode 45 is laminated on the inner surfaces of the reflective layer 44 and the interlayer insulating layer 33, and an uneven surface 45 </ b> A reflecting the uneven portion 44 a of the reflective layer 44 is formed on the common electrode 45 on the reflective display region R side. ing. Further, the dielectric layer 35 is laminated on the common electrode 45. The dielectric layer 35 is provided with a predetermined viscosity and film thickness so as to fill the steps of the concavo-convex portion 45a of the concavo-convex surface 45A of the common electrode 45, and its inner surface in the manufacturing process is a flat surface. The pixel electrode 11 is formed on the inner surface of the dielectric layer 35 that is a flat surface. In this embodiment, the pixel electrode 11 is adjacent to the pixel electrode 11 before the pixel electrode 11 is formed on the dielectric layer 35. The recesses 71 are formed by etching the electrode non-formation regions corresponding to the strips 11b, and the thickness of the dielectric layer 35 is partially reduced. Thereby, even when the dielectric layer 35 becomes thick in the manufacturing process, an electric field can be generated between the pixel electrode 11 and the common electrode 45 at a low voltage. Therefore, power saving can be achieved.

  Also in this embodiment, since the influence of the uneven portion 44a of the reflective layer 44 on the pixel electrode 11 formed on the dielectric layer 35 is eliminated by the dielectric layer itself, the planarization used in the first embodiment is used. A step of separately forming the layer is not necessary. As a result, the number of manufacturing steps can be reduced and the manufacturing efficiency can be improved, and the liquid crystal device can be made thinner and the cost can be reduced accordingly.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, the liquid crystal device may appropriately combine the configurations in the first to third embodiments.

  Moreover, although the uneven | corrugated shape is provided by using the mask which has an opening pattern with respect to the interlayer insulation layer 33 comprised with the photosensitive resin material, or using the gray scale method, it is a plurality using several masks. The concavo-convex shape may be imparted by multiple exposure, or these may be combined.

  In addition, the pixel electrode 11 electrically connected to the TFT element 12 is formed on the liquid crystal layer 23 side of the common electrode 45 through the flattening layer 34 and the dielectric layer 35. Alternatively, the liquid crystal layer 23 may be formed on the liquid crystal layer 23 side with respect to the pixel electrode 11 with the liquid crystal layer 34 and the dielectric layer 35 interposed therebetween. At this time, the common electrode 45 has a strip electrode (corresponding to the strip portion 11b) similarly to the pixel electrode 11 in the above embodiment.

  The pixel electrode 11 and the common electrode 45 form an FFS electrode structure, but an IPS electrode structure may be formed. In this case, for example, each of the pixel electrode 11 and the common electrode 45 has a comb-like shape in plan view, and each has a band-like electrode. Here, the strip electrode constituting the pixel electrode 11 and the strip electrode constituting the common electrode 45 are arranged so as to mesh with each other. Furthermore, the pixel electrode formed in an island shape may be arranged so as to overlap with the common electrode having the strip electrode portion.

  Further, in the pixel region, if the electrode formed above the reflective layer has a strip electrode portion, the liquid crystal layer 23 is not limited to a so-called lateral electric field type liquid crystal device such as an FFS mode or an IPS mode. TN (Twisted Nematic) mode driven by an electric field generated between the sandwiched element substrate 21 and the counter substrate 22, a VAN (Vertically Aligned Nematic) mode having negative dielectric anisotropy, an ECB (Electrically Controlled Birefringence) mode, A liquid crystal device using a liquid crystal that operates in another mode such as an OCB (Optical Compensated Bend) mode may be used.

The liquid crystal device is a transflective liquid crystal device having a reflective display region R and a transmissive display region T, but may be a reflective liquid crystal device having only a reflective display region R. .
The liquid crystal device uses the TFT element 12 as a driving element for switching control of the pixel electrode. However, the liquid crystal device is not limited to the TFT element 12, and other driving elements such as a TFD (Thin Film Diode) element are used. Also good.

  Further, the liquid crystal device is a color liquid crystal device that displays three colors of R, G, and B. However, the liquid crystal device may include a sub-pixel region S that displays other colors, or a structure that displays a single color. It is good. Here, the color filter layer 53 may be provided on the element substrate 21 without providing the color filter layer 53 on the counter substrate 22.

〔Electronics〕
The liquid crystal device 1 having the above configuration is applied as a display unit 101 of a mobile phone 100 as shown in FIG. The cellular phone 100 includes a main body 105 having a plurality of operation buttons 102, a mouthpiece 103, a mouthpiece 104, and the display unit 101.

  As described above, according to the liquid crystal device 1 in the present embodiment, the flattening layer 34 or the dielectric layer 35 is formed so as to fill the steps of the concavo-convex portion 44 a of the reflective layer 44, thereby forming the frame in the reflective display region R. The flatness of the formation surface of the part 11a and the belt-like part 11b becomes higher than before. As a result, it is possible to suppress the occurrence of disconnection or short circuit in the frame portion 11a and the strip portion 11b, and to improve the disturbance of the electric field in the reflective display region R and suppress the alignment failure of the liquid crystal, thereby displaying an image in the reflective display region R. Improved characteristics.

  Electronic devices including a liquid crystal device are not limited to mobile phones, but include PDAs (Personal Digital Assistants), personal computers, notebook personal computers, workstations, digital still cameras, in-vehicle monitors, car navigation systems. Equipment, head-up display, digital video camera, television receiver, viewfinder type or monitor direct-view type video tape recorder, pager, electronic notebook, calculator, electronic book or projector, word processor, video phone, POS terminal, touch panel Other electronic devices such as devices and lighting devices may be used.

1 is an equivalent circuit diagram illustrating a liquid crystal device according to an embodiment of the present invention. It is a plane block diagram of the sub pixel area | region which concerns on embodiment of this invention. It is AA arrow sectional drawing of FIG. It is a principal part enlarged view of FIG. It is sectional drawing which shows the sub pixel area | region in 2nd Embodiment. It is sectional drawing which shows the sub pixel area | region in 3rd Embodiment. It is a perspective view which shows the electronic device which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,60,70 ... Liquid crystal device, 21 ... Element substrate, 22 ... Counter substrate, 23 ... Liquid crystal layer, 44a ... Uneven part, 44 ... Reflective layer, 33 ... Interlayer insulating layer (underlayer), 11 ... Pixel electrode, 45 ... Common electrode, 34 ... Planarizing layer, 35 ... Dielectric layer, 11b ... Band-shaped part (electrode finger), 71 ... Recessed part,
100: Mobile phone (electronic equipment)

Claims (8)

A pair of substrates provided with a plurality of pixel regions having a reflective display region;
A liquid crystal layer sandwiched between the pair of substrates facing each other;
An underlayer having an uneven surface provided in the reflective display region of one of the pair of substrates;
A reflective layer provided on the underlayer and having an uneven portion corresponding to the uneven surface;
A first electrode and a second electrode that are provided above the reflective layer and apply a voltage to the liquid crystal layer;
A liquid crystal device, wherein a planarizing layer is provided between the reflective layer and the first electrode and the second electrode. A pair of substrates provided with a plurality of pixel regions having a reflective display region;
A liquid crystal layer sandwiched between the pair of substrates facing each other;
An underlayer having an uneven surface provided in the reflective display region of one of the pair of substrates;
A first electrode comprising a reflective layer provided on the underlayer and having an uneven portion corresponding to the uneven surface;
A second electrode that is provided above the first electrode and applies a voltage to the liquid crystal layer between the first electrode, and
A liquid crystal device, wherein a planarization layer is provided between the first electrode and the second electrode.     The liquid crystal device according to claim 2, wherein the second electrode is provided above the first electrode with a dielectric layer made of the planarizing layer interposed therebetween. The pixel region is provided with a transmissive display region in which the reflective layer is not formed,
The transmissive display region is provided with a third electrode for applying a voltage to the liquid crystal layer between the second electrode,
The first electrode and the third electrode are provided in the same layer and are electrically connected to each other,
3. The liquid crystal device according to claim 2, wherein the second electrode is provided above the first electrode and the third electrode via a dielectric layer made of the planarizing layer.     5. The liquid crystal according to claim 1, wherein the second electrode is provided above the first electrode via a dielectric layer, and has a plurality of electrode fingers. 6. apparatus. The pixel area is provided with an electrode non-formation area where the second electrode is not formed,
6. The flattening layer according to claim 2, wherein a thickness of a portion overlapping the electrode non-formation region is smaller than a thickness of a portion overlapping the second electrode. Liquid crystal device. A pair of substrates provided with a plurality of pixel regions having a reflective display region;
A liquid crystal layer sandwiched between the pair of substrates facing each other;
An underlayer having an uneven surface provided in the reflective display region of one of the pair of substrates;
A reflective layer provided on the underlayer and having an uneven portion corresponding to the uneven surface;
An electrode that is provided above the reflective layer and has a plurality of strip-shaped electrode portions and applies a voltage to the liquid crystal layer;
A liquid crystal device, wherein a planarizing layer is provided between the reflective layer and the electrode.     An electronic apparatus comprising the liquid crystal device according to claim 1.

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