JP2011059157A - Liquid crystal device and electronic apparatus - Google Patents

Abstract

A liquid crystal device and an electronic apparatus that can suppress a flicker phenomenon and a burn-in phenomenon are provided.
A liquid crystal device includes a first alignment film provided on a first substrate, a second alignment film provided on a second substrate, a first alignment film, and a second alignment film. A liquid crystal layer 40 sandwiched between the first electrode 36 and the second electrode 38, which is provided on the first substrate 16 and applies an electric field to the liquid crystal layer 40 to light-control the liquid crystal layer 40; A first insulating film 92 provided at each interface between the first electrode 36 and the second electrode 38 that generates an electric field; a second insulating film 58 provided on the first substrate 16 and covering the surface of the pixel switching element 34; The first electrode 36 is made of the same material as the second electrode 38, the second alignment film 48 is made of a material having a higher specific resistance than the first alignment film 60, and the first alignment film 60 Is made of a material having a higher specific resistance than the first insulating film 92, and the first insulating film 92 is a second insulating film. Specific resistance is made of a material having lower than 8.
[Selection] Figure 4

Description

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

  In recent years, liquid crystal display devices (liquid crystal devices) constituting display devices such as televisions and graphic displays have been required to have higher definition, smaller size, and higher viewing angle. As one means for increasing the viewing angle, an electric field in the in-plane direction, that is, a transverse electric field is generated with respect to the glass substrate, and the liquid crystal molecules are transmitted by rotating in a plane parallel to the substrate by the transverse electric field. A technique of an optical switching function for changing the rate has been put into practical use. So-called in-plane switching (hereinafter referred to as IPS) using a parallel field parallel to the surface of the glass substrate, or fringe field switching (hereinafter referred to as FFS (Fringe-Field Switching)), which is a further improvement of the IPS method. Liquid crystal display devices that improve the aperture ratio using a method are known.

  Here, in the FFS method, a pixel electrode is disposed on the common electrode through an insulating film, a slit is provided in the pixel electrode, and the slit is used to generate an electric field from the pixel electrode to the common electrode. Yes. This electric field has a strong electric field component in the direction perpendicular to the substrate in the vicinity of the edge of the electrode as well as the lateral electric field, so that the liquid crystal molecules located above the electrode can also be driven. Therefore, if a transparent electrode is used, the electrode portion can also contribute to the display and the aperture ratio is improved.

  The use of the lateral electric field method as described above is useful because a high viewing angle can be realized in a liquid crystal display device, but in a liquid crystal display device in which liquid crystal molecules are driven using a switching element, switching is performed. A bias voltage may be generated at the control terminal of the switching element due to the parasitic capacitance between the control terminal of the element and the output terminal connected to the pixel electrode. This bias voltage is related to the control potential applied to the control terminal, the liquid crystal capacitance component, and the other storage capacitance component. Although this bias voltage is minimized by optimizing the common electrode potential, it differs depending on the image to be displayed. Therefore, the bias voltage cannot be completely removed and causes burn-in.

In order to prevent or suppress such image sticking phenomenon, for example, in an IPS liquid crystal display device, the surface resistance is set to 3. to quickly relieve charges caused by polarization generated in the liquid crystal layer, the alignment film, and the insulating film. Relaxation time represented by the product of the dielectric constant and resistivity of each of the liquid crystal, the alignment film, and the insulating film, using an alignment film or an insulating film in the range of 3 × 10 ^{11 to} 2.5 × 10 ¹⁸ Ω / □ A method for defining the relative relationship between the two has been proposed (see, for example, Patent Document 1).

  On the other hand, in the FFS mode liquid crystal panel, in order to alleviate the electrolytic concentration locally generated in the vicinity of the end of the electrode and to reduce the electric field strength peak value, they are separated from each other through the first insulating film. A second insulating film made of a material different from the first insulating film is disposed between the liquid crystal alignment film and the electrode closer to the liquid crystal alignment film among the formed pixel electrode and common electrode, In addition, a structure that satisfies ε (2)> ε (1) in the dielectric constant ε (1) of the first insulating film and the dielectric constant ε (2) of the second insulating film has been proposed (for example, , See Patent Document 2).

JP-A-7-159786 JP 2003-29247 A

  However, according to the configuration of Patent Document 1, the countermeasure for suppressing the burn-in phenomenon by increasing the relaxation rate of the liquid crystal / alignment film interface may cause a contradiction problem that a flicker phenomenon such as image flickering is likely to occur. In particular, in the region where the electric field strength is concentrated in the lateral electric field drive, for example, in the same plane as the pair of drive electrodes in the IPS method and its peripheral region or in the region near the electrode end of the FFS method, the liquid crystal layer A voltage drop / leak phenomenon is likely to occur, which may occur as a local flicker phenomenon. There is a possibility that flicker is easy to see at the gradation of intermediate length display in which the VT curve has a steep slope.

  On the other hand, according to the configuration of Patent Document 2, it is possible to suppress the image sticking phenomenon and the flicker phenomenon by relaxing the electric field concentration generated locally in the vicinity of the electrode end and lowering the electric field intensity peak value. For driving, there is still a possibility that electric charges are gradually accumulated in the panel due to the bias voltage, and a burn-in phenomenon and a flicker phenomenon occur.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A first substrate provided with a pixel switching element in each of a plurality of pixels, a second substrate facing the first substrate, a first alignment film provided on the first substrate, A second alignment film provided on the second substrate; a liquid crystal layer sandwiched between the first alignment film and the second alignment film; and an electric field applied to the liquid crystal layer provided on the first substrate. A first electrode and a second electrode for dimming the liquid crystal layer; a first insulating film provided at each interface of the first electrode and the second electrode for generating the electric field; A second insulating film provided on one substrate and covering a surface of the pixel switching element, wherein the first electrode is made of the same material as the second electrode, and the second alignment film is The first alignment film is made of a material having a higher specific resistance than the first alignment film, and the first alignment film is higher than the first insulating film. Resistance is composed of a material having high, the first insulating film, a liquid crystal device, characterized in that it consists of the material resistivity is lower than the second insulating film.

  According to this, in the lateral electric field drive liquid crystal panel, the first alignment film having a high electric field strength close to the first electrode has a low specific resistance with an emphasis on the function of easily reducing the charge accumulated by the bias voltage. On the other hand, an alignment film having a specific resistance higher than that of the first alignment film is disposed on the opposing second alignment film having a relatively small electric field strength to suppress the flicker phenomenon. In other words, the second alignment film is disposed so as to face the first alignment film close to the first electrode, and the second alignment film has a higher specific resistance than the first alignment film, thereby causing a flicker phenomenon and a burn-in phenomenon. Can be suppressed.

  In addition, by disposing the first capacitor insulating film having a specific resistance value equal to or lower than that of the first alignment film on the first electrode, locally in the vicinity of the electrode end without affecting the relaxation rate of the accumulated charge. The generated electric field concentration is alleviated, the peak value of the electric field strength applied to the liquid crystal layer is lowered, and the flicker phenomenon is suppressed.

  Further, when the liquid crystal panel is AC driven, if the balance between the positive voltage and the negative voltage applied to the liquid crystal capacitance component is lost, the display quality is remarkably lowered as flickering or flickering of the display image. One cause of such a flicker phenomenon is a small amount of current due to a Schottky barrier at the interface between the first and second electrodes and the insulating films such as the first and second capacitive insulating films and the first and second alignment films. The difference in quantity, that is, the difference in injected charge accumulated in the panel can be mentioned. If there is such a difference in injected charge amount between a positive voltage and a negative voltage in AC driving, the bias voltage changes with time along with the driving time. As a result, the initially optimized second electrode potential fluctuates, and the flicker phenomenon and the burn-in phenomenon deteriorate.

  Therefore, in order to suppress and reduce the influence of the Schottky barrier at the first electrode interface and the second electrode interface and to prevent deterioration of the flicker phenomenon over time, the first electrode and the second electrode formed of the same material are used. For the two electrodes, it is desirable that an insulating film made of the same material be formed at the interface with the electrode surface that generates an electric field when the panel is driven (when the first electrode and the second electrode are formed of different materials) Even if the material of the insulating film in contact with the electrodes is different, it is theoretically possible to balance the positive voltage and the negative voltage, but a very difficult combination of layer structures is required).

  As a result, a liquid crystal device that can suppress the flicker phenomenon and the burn-in phenomenon can be provided. In addition, it is possible to provide a liquid crystal device capable of suppressing flicker phenomenon and image sticking phenomenon in the case of the FFS method or IPS method driven by a lateral electric field.

  Application Example 2 In the above liquid crystal device, the first electrode is provided on the liquid crystal layer side of the first substrate with respect to the liquid crystal layer, and a predetermined area is provided in each region of the pixel. A liquid crystal device having a plurality of slit-like openings provided at intervals.

  According to this, it is possible to easily realize an FFS mode liquid crystal device that drives a liquid crystal by a lateral electric field.

  Application Example 3 In the liquid crystal device, the first electrode and the second electrode are provided in the same layer in the first substrate and have a comb shape, and each comb tooth A liquid crystal device, characterized in that the liquid crystal device is arranged so as to face each other in a state where the portions forming the shape are staggered.

  According to this, it is possible to easily realize an IPS liquid crystal device that drives a liquid crystal by a lateral electric field.

  Application Example 4 In the above liquid crystal device, at least one of the first and second electrodes is embedded in a layer of the first insulating film.

  According to this, the first electrode is made of the same material as that of the second electrode, the first electrode is embedded in the first insulating film layer, and the same first insulating film is formed on the second electrode. By doing so, the time-dependent change of the flicker phenomenon can also be suppressed.

  Application Example 5 In the above-described liquid crystal device, at least one of the first and second electrodes is surrounded by the first insulating film.

  According to this, the first electrode is made of the same material as the second electrode, the first electrode is surrounded by the first insulating film, and the same first insulating film is formed on the second electrode. Therefore, the change with time of the flicker phenomenon can also be suppressed.

  Application Example 6 Electronic equipment including the liquid crystal device according to any one of the above.

  According to this, by providing the liquid crystal device according to any one of the above, it is possible to provide an electronic apparatus that can suppress the flicker phenomenon and the burn-in phenomenon.

FIG. 2 is a configuration diagram showing a schematic configuration of a projector as an electronic apparatus including the liquid crystal device according to the first embodiment as a light modulation element (light valve). Explanatory drawing which showed typically the structure of the liquid crystal device provided with the some pixel which displays an image. FIG. 3 is a schematic plan view showing a state of wiring formed in each pixel for the four pixels exemplified in the upper left portion of the liquid crystal device in FIG. 2. Sectional drawing which follows the A-A 'line of FIG. Sectional drawing of the liquid crystal device which concerns on 2nd Embodiment. Sectional drawing of the liquid crystal device which concerns on 3rd Embodiment. The top view of the several pixel which the TFT array substrate which comprises the liquid crystal device which concerns on 4th Embodiment adjoins. Sectional drawing which follows the B-B 'line of FIG. Sectional drawing of the liquid crystal device which concerns on 5th Embodiment. Explanatory drawing of the electronic device using the liquid crystal device which concerns on this embodiment as a direct view type display apparatus.

(First embodiment)
Hereinafter, description will be made based on the present embodiment. It should be noted that the drawings used in the following description may be exaggerated for the sake of description, and needless to say, they do not necessarily indicate the actual size or length.

  FIG. 1 is a configuration diagram showing a schematic configuration of a projector 4 as an electronic apparatus provided with the liquid crystal device 2 according to the present embodiment as a light modulation element (light valve). The projector 4 changes the irradiation light emitted from the light source 10 to light whose polarization direction is aligned by the polarization beam splitter 12. The irradiation light having the same polarization direction is light-modulated when passing through each pixel provided in the liquid crystal device 2. Then, the projection light 14 projects the irradiation light light-modulated for each pixel on a screen (not shown) installed at a predetermined distance. In this way, the image displayed on the liquid crystal device 2 is projected. Of course, the projector 4 may include a plurality of liquid crystal devices 2 and an optical system (such as a mirror or a cross prism) corresponding to the plurality of liquid crystal devices 2 may be formed.

  In the present embodiment, the polarization direction of the irradiation light aligned by the polarization beam splitter 12 is the Y-axis direction that is the thickness direction (vertical direction in the drawing) of the main body of the projector 4. Although not described here, the vertical direction or the horizontal direction of the display screen is made to coincide with the polarization direction for reasons of manufacturing the polarization beam splitter 12 or for designing the optical system configured in the projector 4. There are many. Therefore, in this embodiment, the polarization direction is the Y-axis direction. Of course, the X-axis direction orthogonal to the Y-axis direction may be used.

  Further, in a state where no image is displayed on the liquid crystal device 2, that is, in an initial state where no voltage is applied between a pixel electrode and a common electrode, which will be described later, in each pixel in the liquid crystal device 2, a black state in which nothing is projected onto the screen is set. Is preferable in use. Therefore, in the projector 4 of this embodiment, the liquid crystal device 2 performs normally black display. Of course, it is possible to perform a normally white display in which a white state is obtained in an initial state where no voltage is applied between the pixel electrode and the common electrode.

  Next, the liquid crystal device 2 will be described. FIG. 2 is an explanatory diagram schematically showing the configuration of the liquid crystal device 2 provided with a plurality of pixels for displaying an image. The liquid crystal device 2 has a structure in which a substrate 16 as a first substrate and a substrate 18 as a second substrate are overlapped with a liquid crystal layer (not shown) sandwiched in a sealed state.

  The substrate 16 has a scanning drive circuit 20, a data drive circuit 22, and a common terminal 24 formed on the outer peripheral portion thereof on a transparent substrate (the drawing surface side) such as glass, quartz, or resin. As shown in FIG. 2, the scanning drive circuit 20 has a scanning line 26 in the X-axis direction, and the data driving circuit 22 has a data line 28 in the Y-axis direction. A thin film transistor (not shown) corresponding to each pixel G is formed near the intersection of the scanning line 26 and the data line 28. Each thin film transistor is controlled to be turned on and off by a voltage supplied by the scanning line 26, and when turned on, a voltage supplied by the data line 28 is applied to a pixel electrode (described later) as a first electrode. It is comprised so that.

  The common terminal 24 supplies a common voltage (for example, ground potential) to a common electrode (described later) formed as a second electrode formed in each pixel G through the common wiring 30 connected thereto. Accordingly, in each pixel G, the differential voltage between the voltage supplied from the data line 28 when the thin film transistor is turned on and the voltage supplied by the common wiring 30 (that is, the voltage of the ground potential) is a liquid crystal layer corresponding to the pixel G. It is comprised so that it may be applied to.

  The substrate 18 has an area corresponding to the pixel G as an opening area (light transmission area), and a predetermined light shielding layer such as a metal film is transparent such as glass, quartz, or resin so that the other area becomes a light shielding area. It is formed on the substrate (the back side of the drawing). Therefore, between the pixels, the light shielding layers 32 are formed in the Y-axis direction and the X-axis direction, respectively. And when the board | substrate 18 is piled up on the board | substrate 16, the light shielding layer 32 is comprised so that the data line 28, the scanning line 26, the common wiring 30, and the thin-film transistor may overlap.

  Next, in the liquid crystal device 2 according to the present embodiment, the state of the pixel electrode and the common electrode formed in each pixel will be described with reference to FIGS. 3 is a schematic plan view showing a state of wiring formed in each pixel G for the four pixels G illustrated in the upper left portion of the liquid crystal device 2 in FIG. 2. The liquid crystal device 2 is viewed from the substrate 18 side. The substrate 18 is shown in a see-through state. FIG. 4 is a schematic diagram showing a partial cross section of the liquid crystal device 2.

  As shown in FIG. 3, data lines 28 are formed on the substrate 16 in the Y-axis direction, and scanning lines 26 are formed in the X-axis direction. A thin film transistor (hereinafter simply referred to as “transistor”) 34 as a pixel switching element is formed in the vicinity of the intersection of both the wirings. That is, a transistor 34 including a source electrode 34 s formed by extending the wiring of the data line 28, a semiconductor layer 34 a formed with a channel region, a gate electrode 34 g serving as the scanning line 26, and a drain electrode 34 d is provided. Is formed. The drain electrode 34d is electrically connected to the pixel electrode 36 as the first electrode via the contact hole CH1. Therefore, when the transistor 34 is turned on by the voltage supplied to the scanning line 26, that is, the gate electrode 34g, the voltage supplied to the data line 28 is applied to the pixel electrode 36 via the drain electrode 34d.

  In the present embodiment, the pixel electrode 36 is rotated clockwise by α degrees (for example, 10 degrees to 20 degrees) clockwise in order to suppress reverse twist with respect to the Y-axis direction in the longitudinal direction of the electrodes. It is assumed that it is formed of three strip electrode portions having a comb-teeth shape that is inclined in the direction), one end is open, and the other end is connected and electrically connected. Of course, the outer contour line of the longitudinal direction of the electrode may be formed to be inclined in the counterclockwise direction (rotation direction to the left side in the drawing) by α degrees (for example, 10 degrees to 20 degrees) with respect to the Y-axis direction. Further, it is sufficient that at least two strip electrode portions are formed. The pixel electrode 36 is provided on the substrate 16 closer to the liquid crystal layer 40 than the common electrode 38, and has a plurality of slit-like openings provided at predetermined intervals in each region of the pixel G. is doing.

  A common wiring 30 is formed on the substrate 16 in the X-axis direction. A common electrode 38 electrically connected to the common wiring 30 via the contact hole CH2 is formed as a solid electrode having a size including the pixel G region. Therefore, in the region of the pixel G, the pixel electrode 36 and the common electrode 38 are formed so as to overlap in a plane.

  A voltage applied between the pixel electrode 36 and the common electrode 38 formed in this manner generates a lateral electric field in the direction along the substrate 16 with respect to the liquid crystal layer 40, and as described above, liquid crystal molecules by the FFS method are used. The orientation control is performed. The pixel electrode 36 is made of the same material as the common electrode 38. For example, the pixel electrode 36 and the common electrode 38 are made of a light-transmitting material having conductivity (for example, indium tin oxide (hereinafter abbreviated as ITO)).

  Next, a cross-sectional configuration of the liquid crystal device 2 will be described with reference to FIG. FIG. 4 is a schematic diagram showing a cross section taken along line AA ′ in FIG. 3. As shown in the figure, the liquid crystal device 2 has a configuration in which a liquid crystal layer 40 is sandwiched between a substrate 16 and a substrate 18. A polarizing plate 42 is attached to the side of the substrate 18 opposite to the liquid crystal layer 40, and a polarizing plate 44 is attached to the side of the substrate 16 opposite to the liquid crystal layer 40 so as to exhibit a predetermined polarization axis direction. In the present embodiment, it is assumed that the liquid crystal layer 40 is formed of positive liquid crystal molecules whose polarization direction is the same as the alignment direction. Of course, it may be formed of negative liquid crystal molecules whose polarization direction is orthogonal to the alignment direction.

  The substrate 18 is obtained by sequentially forming a light shielding layer 32 and a second alignment film 48 on a substrate surface on the liquid crystal layer 40 side with respect to a base material 46 as a flat plate. The light shielding layer 32 is made of a metal film (for example, chromium) or a resin. The second alignment film 48 is made of, for example, a polyimide resin, and is formed so as to cover the light shielding layer 32 and the region of the pixel G. In the substrate 18, a planarization layer or an overcoat layer for planarizing the second alignment film 48 may be formed between the second alignment film 48 and the light shielding layer 32. In the substrate 18, a color filter layer that transmits a predetermined color may be formed at least in a light transmission region corresponding to the region of the pixel G between the base material 46 and the second alignment film 48. .

  The substrate 16 has a scanning line 26 (gate electrode 34g) and a common wiring 30, a gate insulating film 52, a semiconductor layer 34a, a data line 28 (source) on the substrate surface on the liquid crystal layer 40 side with respect to the base material 50 as a flat plate. Electrode 34s), drain electrode 34d, interlayer insulating film 54, planarization layer 56, common electrode 38, first capacitor insulating film 92 as the first insulating film, second capacitor insulating film 58 as the second insulating film, pixel electrode 36, the first capacitor insulating film 92, and the first alignment film 60 are sequentially formed.

  A first capacitor insulating film 92 is formed on the pixel electrode 36 and the common electrode 38, and the pixel electrode 36 and the common electrode 38 are formed of the same material (p-ITO (polycrystalline ITO (poly-ITO)) or the like). ing. Further, the first capacitance insulating film 92 is equal to or less than the specific resistance value of the first alignment film 60, and specifically, a SiNx film is preferable. Further, the second capacitor insulating film 58 is higher in specific resistance than the first capacitor insulating film 92 and is formed with an insulating film having different electrical properties.

  The first capacitor insulating film 92 is formed in contact with each electrode so that the height of the Schottky barrier at the interface of the pixel electrode 36 and the common electrode 38 is the same. Further, by forming a film having a specific resistance lower than that of the first alignment film 60, it has a function of efficiently releasing and mitigating charges accumulated at the interface of the first alignment film 60.

On the other hand, the second capacitor insulating film 58 is formed to balance the withstand voltage and the write capacity between the common electrode 38 and the pixel electrode 36, and the second capacitor insulating film 58 has a specific resistance higher than that of the first capacitor insulating film 92. An insulating film having a high and different electrical property is formed. For example, a combination of SiN and SiO ₂ or a combination of forming two types of silicon nitride films (SiNx) having different film formation conditions can be considered.

  The scanning line 26 (gate electrode 34g), the common wiring 30, the data line 28 (source electrode 34s), and the drain electrode 34d are formed of a metal material (for example, aluminum). The semiconductor layer 34a is made of a semiconductor such as amorphous silicon or polysilicon. The gate insulating film 52 is made of, for example, silicon oxide, the interlayer insulating film 54 is made of, for example, silicon oxide or silicon nitride, the planarizing layer 56 is made of a resin material, and the second capacitor insulating film 58 and the first capacitor insulating film 92 are made of, for example, oxidized. Silicon and silicon nitride are respectively used, and both are formed as a light-transmitting layer. The first alignment film 60 is made of, for example, polyimide resin, and is formed to cover at least the pixel electrode 36 on the side in contact with the liquid crystal layer 40 of the pixel electrode 36.

  In the present embodiment, the liquid crystal device 2 is configured to perform normally black display as described above. In addition, since the liquid crystal layer is formed of positive liquid crystal molecules and the polarization direction of the irradiation light incident on the liquid crystal device 2 from the substrate 18 side is the Y axis direction, the initial alignment direction of the liquid crystal molecules is the Y axis direction. Thus, the first alignment film 60 and the second alignment film 48 are subjected to alignment treatment. That is, the alignment processing directions of the second alignment film 48 and the first alignment film 60 are both Y-axis directions and the pretilt angles are opposite to each other.

The first alignment film 60 and the second alignment film 48 are made of different materials. The second alignment film 48 is made of a material having a higher specific resistance than the first alignment film 60. For example, the material of the first alignment film 60 is SE-6514 manufactured by Nissan Chemical Industries. In addition, the specific resistance value formed by the alignment film forming condition varies in the range of 1.0 × 10 ^{14 to} 1.0 × 10 ¹⁵ Ω · cm. The material of the second alignment film 48 is AL16157 manufactured by JSR Corporation. In addition, the specific resistance value formed by the alignment film forming conditions varies in the range of 1.0 × 10 ^{15 to} 1.0 × 10 ¹⁶ Ω · cm.

  Further, the polarizing plate 42 is attached so as to have a crossed Nicols arrangement in which the transmission axis is in the Y-axis direction and the transmission axis is in the X-axis direction. Of course, in the case where the irradiation light incident on the substrate 18 is polarized light that vibrates substantially only in the Y-axis direction, the polarizing plate 42 on the incident light incident side may be omitted.

  According to the present embodiment, in the horizontal electric field drive liquid crystal panel, the first alignment film 60 that is close to the pixel electrode 36 and has a strong electric field strength emphasizes the function of easily reducing charges accumulated by the bias voltage. An alignment film having a low resistance is disposed. On the other hand, an alignment film having a specific resistance higher than that of the first alignment film 60 is disposed on the opposing second alignment film 48 having a relatively small electric field strength to suppress the flicker phenomenon. .

  Further, by disposing the first capacitor insulating film 92 having a specific resistance value equal to or less than the specific resistance value of the first alignment film 60 on the pixel electrode 36, the first charge insulating film 92 is locally formed in the vicinity of the electrode end without affecting the relaxation rate of the accumulated charge. The concentration of the electric field that occurs is relaxed, the peak value of the electric field strength applied to the liquid crystal layer 40 is lowered, and the flicker phenomenon is suppressed.

  Further, when the liquid crystal panel is AC driven, if the balance between the positive voltage and the negative voltage applied to the liquid crystal capacitance component is lost, the display quality is remarkably lowered as flickering or flickering of the display image. One cause of such a flicker phenomenon is the interface between the pixel and common electrodes 36 and 38 and the first and second capacitor insulating films 92 and 58 and the first and second alignment films 60 and 48. A small amount of current difference due to the Schottky barrier, that is, a difference in injected charge accumulated in the panel can be mentioned. If there is such a difference in injected charge amount between a positive voltage and a negative voltage in AC driving, the bias voltage changes with time along with the driving time. As a result, the initially optimized potential of the common electrode 38 fluctuates, and the flicker phenomenon and the burn-in phenomenon deteriorate.

  Accordingly, in order to suppress and reduce the influence of the Schottky barrier at the interface between the pixel electrode 36 and the common electrode 38 and to prevent the flicker phenomenon from deteriorating over time, the pixel electrode 36 and the common electrode formed with the same material are used. It is desirable that an insulating film made of the same material is formed on the electrode 38 at the interface with the electrode surface that generates an electric field when the panel is driven (when the pixel electrode 36 and the common electrode 38 are formed of different materials). Even if the material of the insulating film in contact with the electrodes is different, it is theoretically possible to balance the positive voltage and the negative voltage, but a very difficult combination of layer structures is required).

(Second Embodiment)
The liquid crystal device according to this embodiment is the same as the liquid crystal device 2 according to the first embodiment except for the configuration of the pixel electrode 36 and the first capacitor insulating film 92.
FIG. 5 is a cross-sectional view of the liquid crystal device 6 according to the present embodiment. In the liquid crystal device 6, the substrate 16 has a scanning line 26 (gate electrode 34 g), a common wiring 30, a gate insulating film 52, and a semiconductor layer 34 a on the substrate surface on the liquid crystal layer 40 side with respect to the base material 50 as a flat plate. , Data line 28 (source electrode 34s) and drain electrode 34d, interlayer insulating film 54, planarization layer 56, common electrode 38, first capacitor insulating film 92, second capacitor insulating film 58, pixel electrode 36, first capacitor insulating The film 92 and the first alignment film 60 are sequentially formed.

  In the present embodiment, the pixel electrode 36 is embedded in the layer of the first capacitor insulating film 92.

  According to the liquid crystal device 6 according to the present embodiment, the same effect as that obtained by the liquid crystal device 2 according to the first embodiment can be obtained.

(Third embodiment)
The liquid crystal device according to this embodiment is the same as the liquid crystal device 2 according to the first embodiment except for the configuration of the pixel electrode 36 and the first capacitor insulating film 92.
FIG. 6 is a cross-sectional view of the liquid crystal device 8 according to the present embodiment. In the liquid crystal device 8, the substrate 16 has a scanning line 26 (gate electrode 34g), a common wiring 30, a gate insulating film 52, and a semiconductor layer 34a on the substrate surface on the liquid crystal layer 40 side with respect to the base material 50 as a flat plate. , Data line 28 (source electrode 34s) and drain electrode 34d, interlayer insulating film 54, planarization layer 56, common electrode 38, first capacitor insulating film 92, second capacitor insulating film 58, pixel electrode 36, first capacitor insulating The film 92 and the first alignment film 60 are sequentially formed.

  In the present embodiment, the pixel electrode 36 is surrounded by the first capacitor insulating film 92.

  According to the liquid crystal device 8 according to the present embodiment, the same effect as that obtained by the liquid crystal device 2 according to the first embodiment can be obtained.

(Fourth embodiment)
The liquid crystal device of the present embodiment is an example of an IPS-type transmissive liquid crystal device that is intended for use as a liquid crystal light valve of a projector.
FIG. 7 is a plan view of a plurality of adjacent pixels on the TFT array substrate constituting the liquid crystal device. 8 is a cross-sectional view taken along the line BB ′ in FIG. 7 and 8, the same reference numerals are given to the same components as the components according to the first embodiment shown in FIGS. 3 and 4, and description thereof will be omitted as appropriate.

  As shown in FIGS. 7 and 8, the liquid crystal device 96 according to the present embodiment includes a plurality of data lines 28 and a plurality of scanning lines 26 arranged in a grid pattern on a TFT array substrate 62 as a first substrate. A plurality of pixels G corresponding to a region surrounded by the data lines 28 and the scanning lines 26 are provided in a matrix. Corresponding to each pixel G, a pixel electrode 66 as a first electrode and a common electrode 74 as a second electrode are provided. The scanning line 26 is electrically connected to the gate electrode 78 of the semiconductor layer 76 facing the channel region 76a through the contact hole CH3. The pattern of the gate electrode 78 is included inside the pattern of the scanning line 26. It has become a form. A TFT 68 serving as a pixel switching element in which the gate electrode 78 is opposed to the channel region 76a is provided at a location where the gate electrode 78 and the data line 28 intersect.

  As shown in FIG. 8, the liquid crystal device 96 includes a TFT array substrate 62 having a base material 50 and a counter substrate 64 as a second substrate having a base material 46. A pixel electrode 66 and a common electrode 74 are provided on the TFT array substrate 62, and a first alignment film 60 that has been subjected to a predetermined alignment process such as a rubbing process is provided on the upper layer side thereof. The pixel electrode 66 is made of a transparent conductive material such as ITO. On the other hand, a second alignment film 48 subjected to a predetermined alignment process such as a rubbing process is provided on the counter substrate 64. Between the TFT array substrate 62 and the counter substrate 64, liquid crystal is sealed in a space surrounded by a sealing material (not shown) to form a liquid crystal layer 40. The liquid crystal layer 40 takes a predetermined initial alignment state by the first and second alignment films 60 and 48 in a state where no electric field is applied.

  On the TFT array substrate 62, in addition to the pixel electrode 66, the common electrode 74, and the first alignment film 60 described above, various components including these are provided in a laminated structure. In order from the bottom in FIG. 8, the layer including the scanning line 26 is “first layer”, the layer including the gate electrode 78, the TFT 68, etc. is “second layer”, the layer including the storage capacitor 72 is “third layer”, and the data The layer including the line 28 and the like is the “fourth layer”, the layer including the capacitor wiring 70 and the like is the “fifth layer”, the pixel electrode 66, the common electrode 74, the first capacitor insulating film 92, the first alignment film 60 and the like. The containing layer is referred to as “sixth layer (uppermost layer)”. Also, a base insulating film 80 is provided between the first layer and the second layer, a first interlayer insulating film 82 is provided between the second layer and the third layer, and a space between the third layer and the fourth layer is provided. The second interlayer insulating film 84, the third interlayer insulating film 86 between the fourth layer and the fifth layer, and the fourth interlayer insulating film (second capacitor insulating film) between the fifth layer and the sixth layer 58 are provided to prevent a short circuit between the aforementioned elements. These various insulating films 80, 82, 84, 86, 58 are also provided with contact holes for electrically connecting the upper and lower conductive layers.

(Configuration of pixel electrode and common electrode)
Next, the configuration of the pixel electrode 66 and the common electrode 74, which is the greatest feature of the present embodiment, will be described with reference to FIG.

  In the present embodiment, as shown in FIG. 8, the pixel electrode 66 and the common electrode 74 are embedded in the first capacitor insulating film 92 layer. The pixel electrode 66 includes two strip electrode portions 66a (electrode portions) and a connecting portion 66b that connects the two strip electrode portions 66a, and is formed in a so-called U-shape. Here, although each part of the pixel electrode 66 is referred to as a strip electrode part and a connection part, it is actually an integral electrode pattern, and is formed of a transparent conductive material such as ITO, for example. The two strip electrode portions 66a extend in a direction obliquely intersecting the data lines 28 and the scanning lines 26, and are arranged in parallel to each other. In the present embodiment, the angle formed by the extending direction of the strip electrode portion 66a and the extending direction of the scanning line 26 is set to 70 degrees. The pixel electrode 66 is connected to the connecting portion 66b on the lower end side of each strip electrode portion 66a in FIG. 7, and the upper end side of each strip electrode portion 66a is an open end.

  On the other hand, the common electrode 74, like the pixel electrode 66, has two strip electrode portions 74a and a connecting portion 74b connecting the two strip electrode portions 74a, and is formed in a U shape. The common electrode 74 is also an integral pattern formed of a transparent conductive material such as ITO. The two strip electrode portions 74a extend in parallel to each other so as to form an angle of 70 degrees with respect to the extending direction of the scanning line 26. Contrary to the pixel electrode 66, the common electrode 74 is connected to the connecting portion 74b on the upper end side of each strip electrode portion 74a in FIG. 7, and the lower end side of each strip electrode portion 74a is an open end. Since the pixel electrode 66 and the common electrode 74 are formed of a transparent conductive material such as ITO, the portion directly above the strip-like electrode portions 66a and 74a of the electrodes 66 and 74 can contribute to display to some extent, so that the aperture ratio is further increased. be able to.

  One strip electrode portion 74 a of the common electrode 74 is disposed between the two strip electrode portions 66 a of the pixel electrode 66, and one pixel electrode 66 is disposed between the two strip electrode portions 74 a of the common electrode 74. A strip electrode portion 66a is disposed. That is, the U-shaped pixel electrode 66 and the common electrode 74 are disposed so as to mesh with each other, and when viewed along the extending direction of the scanning line 26, the band-shaped electrode portion 66a of the pixel electrode 66 and the band-shaped of the common electrode 74 are arranged. The electrode portions 74a are alternately arranged one by one. Most of the two strip electrode portions 66a of the pixel electrode 66 are located in the light transmission region of each pixel G in which the black matrix 90 is opened. On the other hand, most of the one strip electrode portion 74a (the left strip electrode portion 74a in FIG. 7) of the two strip electrode portions 74a of the common electrode 74 is located in the light transmission region of each pixel G. However, the remaining one strip electrode portion 74a (the right strip electrode portion 74a in FIG. 7) intersects the data line 28 (not shown in FIG. 7), the capacitor wiring 70, etc., and extends in the extending direction of the scanning line 26. It is arranged across two adjacent pixels G along the same line.

  According to the liquid crystal device 96 according to the present embodiment, the same effect as that obtained by the liquid crystal device 2 according to the first embodiment can be obtained.

(Fifth embodiment)
The liquid crystal device according to the present embodiment is the same as the liquid crystal device 96 according to the fourth embodiment except for the configuration of the pixel electrode 66 and the first capacitor insulating film 92.
FIG. 9 is a cross-sectional view of the liquid crystal device 98 according to the present embodiment. In this liquid crystal device 98, in order from the bottom in FIG. 9, the layer including the scanning line 26 is “first layer”, the layer including the gate electrode 78, the TFT 68, etc. is “second layer”, and the layer including the storage capacitor 72 is “ The “third layer”, the layer including the data line 28 and the like as the “fourth layer”, the layer including the capacitor wiring 70 and the like as the “fifth layer”, the pixel electrode 66, the common electrode 74, the first capacitor insulating film 92, and the A layer including the first alignment film 60 and the like is referred to as a “sixth layer (uppermost layer)”.
Also, a base insulating film 80 is provided between the first layer and the second layer, a first interlayer insulating film 82 is provided between the second layer and the third layer, and a space between the third layer and the fourth layer is provided. The second interlayer insulating film 84, the third interlayer insulating film 86 between the fourth layer and the fifth layer, and the fourth interlayer insulating film (second capacitor insulating film) between the fifth layer and the sixth layer 58 are provided to prevent a short circuit between the aforementioned elements.

  In the present embodiment, the pixel electrode 66 and the common electrode 74 are surrounded by the first capacitor insulating film 92.

  According to the liquid crystal device 98 according to the present embodiment, the same effect as that obtained by the liquid crystal device 96 according to the fourth embodiment can be obtained.

(Electronics)
In the above embodiment, the liquid crystal device 2 is used as a light valve of the projector 4 shown in FIG. 1, but the liquid crystal device 2 may be used in a direct-view display device of an electronic device described below.

  FIG. 10 is an explanatory diagram of an electronic device that uses the reflective liquid crystal device 2 according to the present embodiment as a direct-view display device. First, the cellular phone 100 illustrated in FIG. 10A includes a plurality of operation buttons 102, a scroll button 104, and the liquid crystal device 2 as a display unit. By operating the scroll button 104, the screen displayed on the liquid crystal device 2 is scrolled. A personal digital assistant (PDA) 200 shown in FIG. 10B includes a plurality of operation buttons 202, a power switch 204, and the liquid crystal device 2 as a display unit. When the power switch 204 is operated, Various kinds of information such as an address book and a schedule book are displayed on the liquid crystal device 2. In addition to the electronic devices shown in FIGS. 10A and 10B, the electronic apparatus on which the liquid crystal device 2 according to this embodiment is mounted includes a head mounted display, a digital still camera, a liquid crystal television, a viewfinder type, a monitor. Examples include direct-view video tape recorders, car navigation devices, pagers, electronic notebooks, calculators, word processors, workstations, videophones, POS terminals, and bank terminals.

  DESCRIPTION OF SYMBOLS 2 ... Liquid crystal device 4 ... Projector 6,8 ... Liquid crystal device 10 ... Light source 12 ... Polarizing beam splitter 14 ... Projection lens 16 ... Substrate (first substrate) 18 ... Substrate (second substrate) 20 ... Scanning drive circuit 22 ... Data drive Circuit 24 ... Common terminal 26 ... Scanning line 28 ... Data line 30 ... Common wiring 32 ... Light shielding layer 34 ... Thin film transistor (pixel switching element) 34a ... Semiconductor layer 34g ... Gate electrode 34d ... Drain electrode 34s ... Source electrode 36 ... Pixel electrode (First electrode) 38 ... common electrode (second electrode) 40 ... liquid crystal layer 42 ... polarizing plate 44 ... polarizing plate 46 ... substrate 48 ... second alignment film 50 ... substrate 52 ... gate insulating film 54 ... interlayer insulating film 56 ... Planarization layer 58 ... Second capacitor insulating film (fourth interlayer insulating film) (second insulating film) 60 ... First alignment film 62 ... TFT A substrate (first substrate) 64 ... counter substrate (second substrate) 66 ... pixel electrode (first electrode) 66a ... strip electrode part 66b ... connection part 68 ... TFT (pixel switching element) 70 ... capacitor wiring 72 ... storage capacitor 74 ... Common electrode (second electrode) 74a ... Band-shaped electrode part 74b ... Connection part 76 ... Semiconductor layer 76a ... Channel region 78 ... Gate electrode 80 ... Base insulating film 82 ... First interlayer insulating film 84 ... Second interlayer insulating film 86 ... third interlayer insulating film 90 ... black matrix 92 ... first capacitor insulating film (first insulating film) 96, 98 ... liquid crystal device 100 ... mobile phone 102 ... operating button 104 ... scroll button 200 ... information portable terminal 202 ... operating button 204: Power switch.

Claims (6)

A first substrate provided with a pixel switching element in each of a plurality of pixels;
A second substrate facing the first substrate;
A first alignment film provided on the first substrate;
A second alignment film provided on the second substrate;
A liquid crystal layer sandwiched between the first alignment film and the second alignment film;
A first electrode and a second electrode, provided on the first substrate, for dimming and driving the liquid crystal layer by applying an electric field to the liquid crystal layer;
A first insulating film provided at each interface between the first electrode and the second electrode that generates the electric field;
A second insulating film provided on the first substrate and covering a surface of the pixel switching element;
Including
The first electrode is made of the same material as the second electrode,
The second alignment film is made of a material having a higher specific resistance than the first alignment film,
The first alignment film is made of a material having a higher specific resistance than the first insulating film,
The liquid crystal device, wherein the first insulating film is made of a material having a specific resistance lower than that of the second insulating film. The liquid crystal device according to claim 1,
The first electrode is provided on the liquid crystal layer side of the first substrate with respect to the second electrode, and has a plurality of slit-like shapes provided at predetermined intervals in each region of the pixel. A liquid crystal device having an opening. The liquid crystal device according to claim 1,
The first electrode and the second electrode are provided in the same layer in the first substrate and have a comb shape, and are opposed to each other in a state in which the portions forming the comb shape are staggered. A liquid crystal device, wherein the liquid crystal device is disposed as a liquid crystal device. The liquid crystal device according to any one of claims 1 to 3,
At least one of the first and second electrodes is embedded in the layer of the first insulating film. The liquid crystal device according to any one of claims 1 to 3,
At least one of the first and second electrodes is surrounded by the first insulating film.   The electronic device provided with the liquid crystal device as described in any one of Claims 1-5.