JP4760223B2 - Liquid crystal device and electronic device - Google Patents

Description

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

  In particular, in the field of liquid crystal devices represented by liquid crystal televisions and the like, in recent years, an OCB (Optical Compensated Bend) mode liquid crystal device having a high response speed has been spotlighted for the purpose of improving the quality of moving images. In the OCB mode, in the initial state, the liquid crystal molecules are in a splay alignment that is opened in a splay shape between two substrates, and the liquid crystal molecules must be bent in a bow (bend alignment) during display operation. . That is, high-speed response is realized by modulating the transmittance with the degree of bending of the bend orientation during the display operation.

  As described above, in the case of the OCB mode liquid crystal device, since the liquid crystal is in the splay alignment when the power is shut off, by applying a voltage higher than a certain threshold voltage to the liquid crystal when the power is turned on, the initial splay alignment is changed to the bend alignment in the display operation. A so-called initial transition operation is required to shift the alignment state of the liquid crystal. Here, if the initial transition is not sufficiently performed, display failure may occur or desired high-speed response may not be obtained.

Therefore, in Patent Document 1, a protrusion as an alignment transition means is formed on the surface of the transmissive display electrode in the transflective liquid crystal display device to assist the transition of the liquid crystal molecules from the splay alignment to the bend alignment when a voltage is applied. Techniques to do this have been proposed. In this transflective liquid crystal display device, when the liquid crystal molecules in the transmissive display region are in bend alignment, the liquid crystal molecules in the reflective display region are in a hybrid alignment with the long axis perpendicular to the surface of the reflective display electrode. Controlled. Accordingly, when the panel is driven, the transmissive display area is in the OCB mode, and the reflective display area is in the R-OCB (Reflective-Optical Compensated Bend) mode.
JP 2002-207227 A

  However, the technique described in Patent Document 1 has a problem that alignment failure occurs around the protrusions formed in the transmissive display region during the display operation. Further, if the formation region of the protrusion is covered with a light shielding layer, the aperture ratio is reduced. In addition, since the liquid crystal alignment state in the reflective display region is set to hybrid alignment, it is necessary to make only the alignment film in the reflective display region vertical alignment by photo-alignment processing or the like, which increases the manufacturing process.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a liquid crystal device capable of smoothly performing the initial transition operation in the OCB mode while minimizing deterioration in display quality. And
Another object is to provide an electronic device with excellent display quality.

In order to achieve the above object, a liquid crystal device according to the present invention includes a pair of substrates that face each other and sandwich a liquid crystal layer, an alignment film that is disposed on the pair of substrates, and one of the pair of substrates. Electrodes arranged in a matrix on the substrate for applying a voltage to the liquid crystal layer, switching elements for controlling energization of the electrodes, scanning lines for supplying scanning signals to the switching elements, and the scanning lines A data line that is arranged so as to intersect with the image line and supplies an image signal; a reflective film that is provided on one of the pair of substrates and reflects light incident from the other substrate side; and smaller than the thickness of the liquid crystal layer thickness of the liquid crystal layer in the transmissive display region, the retardation of the liquid crystal layer in the reflective display region and the transmissive display region in substantially the same A liquid crystal device in which an operation mode of the liquid crystal layer in at least the transmissive display region is an OCB mode, wherein the liquid crystal device is provided between the reflective display region and the transmissive display region. An initial transition structure of the liquid crystal layer is provided in a formation region of the inclined portion of the liquid crystal layer thickness adjusting layer, the scanning line is arranged in a region overlapping the inclined portion in a plane, and the alignment film is formed of the data line A rubbing process is performed in a direction intersecting with.

In addition, the liquid crystal device according to the reference invention includes a pair of substrates arranged to face each other and sandwiching a liquid crystal layer, and a reflection that reflects light incident on one of the pair of substrates and incident from the other substrate side. A liquid crystal layer thickness adjusting layer that makes the thickness of the liquid crystal layer in the reflective display region smaller than the thickness of the liquid crystal layer in the transmissive display region, and at least an operation mode of the liquid crystal layer in the transmissive display region is In the liquid crystal device in OCB mode, an initial transition structure of the liquid crystal layer is provided in a formation region of an inclined portion of the liquid crystal layer thickness adjusting layer provided between the reflective display region and the transmissive display region. It is characterized by.
If an initial transition structure is provided and disclination is generated by applying an initial transition voltage, the disclination becomes a transition nucleus and the initial transition proceeds to the periphery. Therefore, the initial transition operation can be performed smoothly.
In general, in the inclined portion of the liquid crystal layer thickness adjusting layer, liquid crystal molecules are inclined and an oblique electric field is generated, so that the alignment state is more likely to be disturbed than in the flat portion. That is, the inclined portion of the liquid crystal layer thickness adjusting layer does not contribute to the improvement of display quality during the display operation. Therefore, by providing an initial transition structure in the inclined portion of the liquid crystal layer thickness adjustment layer, even if disclination remains around the initial transition structure, it is possible to minimize the deterioration in display quality during display operation. it can. By providing the initial transition structure in such an inclined portion, it becomes easier to generate disclination than in the case of providing the initial transition structure in other portions. Therefore, the initial transition operation can be performed smoothly.

The operation mode of the liquid crystal layer in the reflective display region may be an OCB mode.
According to this configuration, it is not necessary to separately form an alignment film of liquid crystal molecules between the reflective display region and the transmissive display region, so that the manufacturing cost can be reduced.

The operation mode of the liquid crystal layer in the reflective display region may be an R-OCB mode.
According to this configuration, since the initial transition operation of the reflective display area is not necessary, the initial transition operation can be performed smoothly.

The initial transition structure may be a slit and / or a notch formed in an electrode for applying a voltage to the liquid crystal layer.
According to this configuration, oblique electric fields in various directions can be generated by applying the initial transition voltage. Thereby, it is possible to generate disclination on the surface of the inclined portion, and the initial transfer operation can be performed smoothly.

The initial transition structure may be a surface of an electrode for applying a voltage to the liquid crystal layer, or a protrusion formed under the electrode.
According to this configuration, initial liquid crystal molecules can be tilted in various directions, and oblique electric fields in various directions can be generated by applying an initial transition voltage. Thereby, it is possible to generate disclination on the surface of the inclined portion, and the initial transfer operation can be performed smoothly.

The inclined portion may be provided in the reflective display area.
In general, in the inclined portion of the liquid crystal layer thickness adjusting layer, the alignment state of the liquid crystal molecules tends to be disturbed, and the display quality tends to deteriorate. Therefore, by disposing the inclined portion in the reflective display region, it is possible to provide a liquid crystal device that places importance on transmissive display.

The inclined portion may be provided in the transmissive display area.
According to this configuration, it is possible to provide a liquid crystal device that places importance on reflective display.

Further, it is desirable that a light shielding film is formed in a region overlapping the inclined portion in a plan view.
According to this configuration, even if disclination remains around the initial transition structure, light leakage due to the disclination can be prevented. Therefore, it is possible to minimize the deterioration of display quality.

Further, it is desirable that a signal line for driving the liquid crystal layer is formed in a region overlapping the inclined portion in a plan view.
According to this configuration, an electric field generated around the signal line can be applied to the inclined portion, and it is easy to generate disclination in the inclined portion. Therefore, the initial transition operation can be performed smoothly. Even if disclination remains around the initial transition structure, light leakage due to the disclination can be prevented. Therefore, it is possible to minimize the deterioration of display quality.

On the other hand, an electronic apparatus according to the present invention includes the above-described liquid crystal device.
The liquid crystal device described above can smoothly perform the initial transition operation in the OCB mode while minimizing the deterioration in display quality, and thus can provide an electronic device with excellent display quality.

Hereinafter, embodiments and reference embodiments of the present invention will be described with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.
In the present specification, the liquid crystal layer side of each component of the liquid crystal device is referred to as an inner side, and the opposite side is referred to as an outer side. In addition, a display area that is a minimum unit of image display is referred to as a “dot area”, and a set of a plurality of dot areas including each color filter is referred to as a “pixel area”. In the dot area, an area that can display using light incident from the display surface side of the liquid crystal device is called a “reflective display region” and is incident from the back side of the liquid crystal device (the side opposite to the display surface). An area that can be displayed using the light is referred to as a “transparent display area”. “When a non-selection voltage is applied” and “when a selection voltage is applied” are respectively “when the applied voltage to the liquid crystal layer is close to the threshold voltage of the liquid crystal” and “the applied voltage to the liquid crystal layer is It means “when sufficiently high compared to the threshold voltage”.

(First reference form)
First, a liquid crystal device according to a first reference embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 2, the liquid crystal device 100 according to the first reference embodiment is an active matrix type liquid crystal device that employs a thin film diode (hereinafter referred to as “TFD”) element 13 as a switching element. 3, the TFD array substrate (hereinafter referred to as “element substrate”) 10 disposed on the observer side, the counter substrate 20 disposed on the light source side, and the element substrate 10 and the counter substrate 20 are sandwiched. The thickness of the liquid crystal layer 50 in the reflective display region R in which the liquid crystal layer 50 is provided, the reflective film 27 provided on the counter substrate 20 side and reflecting the light incident from the element substrate 10 side, and the reflective film 27 exists. This is a transflective liquid crystal device having a liquid crystal layer thickness adjusting layer 24 for reducing the thickness of the liquid crystal layer 50 in the transmissive display region T where no reflective film 27 is present.

(Equivalent circuit)
FIG. 1 is an equivalent circuit diagram of a liquid crystal device using a TFD element. In the liquid crystal device 100, a plurality of scanning lines 8 driven by the scanning signal driving circuit 104 and a plurality of data lines 9 driven by the data signal driving circuit 101 are arranged in a grid pattern. A TFD element 13 and a liquid crystal display element (liquid crystal layer) 50 are disposed in the vicinity of the intersection of each scanning line 8 and each data line 9. Each TFD element 13 and each liquid crystal layer 50 are connected in series between each scanning line 8 and each data line 9.

(Planar structure)
FIG. 2 is a partial perspective view of a display area of a liquid crystal device using a TFD element. The liquid crystal device 100 of this reference embodiment includes an element substrate 10 disposed on the viewer side, a counter substrate 20 arranged on the light source side, and the clamping has been not shown liquid crystal layer between a pair of substrates 10 and 20 Is the main constituent. The counter substrate 20 may be disposed on the observer side, and the element substrate 10 may be disposed on the light source side.

  The element substrate 10 includes a substrate body 11 made of a translucent material such as glass, plastic, or quartz. A plurality of scanning lines 8 are provided in stripes on the inner side (lower side in the figure) of the substrate body 11. A plurality of pixel electrodes 15 made of a transparent conductive material such as ITO (indium tin oxide) are arranged in a matrix and are connected to the scanning lines 8 through the TFD elements 13.

  One counter substrate 20 also includes a substrate body 21 made of a translucent material such as glass, plastic, or quartz. A CF layer 22 including a plurality of color filters (hereinafter referred to as “CF”) 22 </ b> B, 22 </ b> G, and 22 </ b> R that transmit different color lights is formed inside the substrate body 21 (upper side in the drawing). The CF layer 22 may be formed on the element substrate 10. A strip electrode 25 is formed so as to cover the CF layer 22. The strip electrode 25 functions as the data line described above, and extends in a direction intersecting the scanning line 8 of the element substrate 10. The strip electrode 25 of the counter substrate 20 may function as a scanning line, and the scanning line 8 of the element substrate 10 may function as a data line.

(Cross-section structure)
FIG. 3 is an explanatory diagram of the liquid crystal device according to the first reference embodiment, FIG. 3A is a cross-sectional view taken along line BB in FIG. 3B, and FIG. 3B is FIG. It is a top view which follows the AA line of ().
As shown in FIG. 3A, a resin layer 26 having an uneven surface is provided inside the counter substrate 20. The resin layer 26 is formed at one end portion in the longitudinal direction of the dot region serving as an image display unit. On the surface of the resin layer 26, a reflective film 27 made of a highly reflective metal material such as Al or Ag is formed. Since unevenness is formed on the surface of the reflection film 27, incident light from the element substrate 10 side can be scattered and reflected. A CF layer 22 including a color filter that transmits different color light for each dot region is provided inside the counter substrate 20 on which the reflective film 27 is formed.

  The color filter is preferably divided into two types of regions having different chromaticities in the dot region. As a specific example, a first color material region is provided corresponding to the planar region of the transmissive display region T, and a second color material region is provided corresponding to the planar region of the reflective display region R. A configuration in which the chromaticity of the first color material region is larger than the chromaticity of the second color material region can be employed. Moreover, it is good also as a structure which provides a non-colored area | region in a part of reflective display area | region R. FIG. By adopting such a configuration, it is possible to prevent the chromaticity of the display light from being different between the transmissive display region T where the display light is transmitted only once through the color filter and the reflective display region R where the display light is transmitted twice. The display quality can be improved by aligning the appearance of the reflective display and the transmissive display.

  A liquid crystal layer thickness adjusting layer 24 is formed on the surface of the CF layer 22 corresponding to the formation region of the reflective film 27. In the transflective liquid crystal device, incident light to the reflective display region R passes through the liquid crystal layer 50 twice, but incident light to the transmissive display region T passes through the liquid crystal layer 50 only once. As a result, if the retardation of the liquid crystal layer 50 is different between the reflective display region R and the transmissive display region T, a difference in light transmittance occurs, and a uniform image display cannot be obtained. Therefore, by providing the liquid crystal layer thickness adjusting layer 24, the layer thickness (for example, about 2 μm) of the liquid crystal layer 50 in the reflective display region R is about half of the layer thickness (for example, about 4 μm) of the liquid crystal layer 50 in the transmissive display region T. Thus, the retardation of the liquid crystal layer 50 in the reflective display region R and the transmissive display region T is set to be substantially the same. In this way, a multi-gap structure is realized by the liquid crystal layer thickness adjusting layer 24, and uniform image display can be obtained in the reflective display region R and the transmissive display region T.

In the boundary region between the reflective display region R and the transmissive display region T, an inclined portion 70 of the liquid crystal layer thickness adjusting layer 24 is formed. Thereby, the layer thickness of the liquid crystal layer 50 continuously changes from the reflective display region R to the transmissive display region T. The inclination angle of the inclined portion is about 10 ° to 30 °. In general, in the inclined portion 70 of the liquid crystal layer thickness adjusting layer 24, the alignment state of liquid crystal molecules is likely to be disturbed, and the display quality is likely to deteriorate. Therefore the liquid crystal device according to the first reference embodiment, by arranging the inclined portion 70 in the transmissive display region T, has a structure with an emphasis on reflective display.

  As a constituent material of the liquid crystal layer thickness adjusting layer 24, it is desirable to employ a material having electrical insulation and photosensitivity such as acrylic resin. By adopting the photosensitive material, patterning using photolithography is possible, and the liquid crystal layer thickness adjusting layer 24 can be formed with high accuracy. The liquid crystal layer thickness adjusting layer 24 may be provided on the element substrate 10 or on both the element substrate 10 and the counter substrate 20.

  On the inner side of the counter substrate 20 on which the liquid crystal layer thickness adjusting layer 24 is formed, the above-described band-like electrode 25 is formed. An alignment film 29 made of polyimide or the like is formed on the surface of the strip electrode 25. An alignment film 19 made of polyimide or the like is also formed on the surface of the pixel electrode 15 formed on the element substrate 10. These alignment films 19 and 29 are subjected to a para-rubbing process so that the alignment of the liquid crystal molecules is vertically symmetric with respect to the center of the liquid crystal layer 50 in the thickness direction. The rubbing process is performed along the extending direction of the scanning line 8 (that is, the longitudinal direction of the pixel electrode 15) as indicated by an arrow 19a in FIG.

The peripheral portions of the element substrate 10 and the counter substrate 20 shown in FIG. 3A are bonded together by a sealing material (not shown), and the liquid crystal layer 50 is sealed inside the sealing material. In this preferred embodiment, the transmissive display region T and the reflective display region R together horizontal alignment film is formed, the liquid crystal layer 50 in the transmissive display region T and the reflective display region R, is adapted to operate in both OCB mode.

  FIG. 4 is an explanatory diagram of the alignment state of liquid crystal molecules in the OCB mode liquid crystal device. In the OCB mode, in the initial state shown in FIG. 4B, the liquid crystal molecules 51 are in a splay alignment in which they are opened in a splay shape. In the display operation shown in FIG. 4A, the liquid crystal molecules 51 are bent like a bow (bend alignment). In addition, high-speed response of the display operation can be realized by modulating the transmittance with the degree of bending of the bend orientation during the display operation.

  Returning to FIG. 3A, polarizing plates 36 and 37 are provided outside the pair of substrates 10 and 20, respectively. These polarizing plates 36 and 37 transmit only linearly polarized light that vibrates in a specific direction. The transmission axis of the polarizing plate 36 and the transmission axis of the polarizing plate 37 are arranged so as to be substantially orthogonal to each other, and are arranged so as to intersect the rubbing direction of the alignment films 19 and 29 at about 45 °.

  In addition, you may arrange | position the phase difference plate 31 and the phase difference plate 32 inside the polarizing plate 36 and the polarizing plate 37 as needed. If a λ / 4 plate having a phase difference of approximately ¼ wavelength with respect to the wavelength of visible light is used as the phase difference plates 31 and 32, a circularly polarizing plate can be configured together with the polarizing plates 36 and 37. If a λ / 2 plate and a λ / 4 plate are used in combination, a broadband circularly polarizing plate can be configured.

  Furthermore, you may arrange | position an optical compensation film inside the polarizing plate 36 and / or the polarizing plate 37 as needed. By disposing the optical compensation film, it is possible to compensate for the phase difference of the liquid crystal layer when the liquid crystal device is viewed from the front or from the perspective, and it is possible to reduce light leakage and increase contrast. As the optical compensation film, it is possible to use a negative uniaxial medium (for example, WV film made by Fuji Film) formed by hybrid alignment of discotic liquid crystal molecules having negative refractive index anisotropy. It is also possible to use a positive uniaxial medium (for example, NH film manufactured by Nippon Petroleum) formed by hybrid alignment of nematic liquid crystal molecules having a positive refractive index anisotropy. Further, a negative uniaxial medium and a positive uniaxial medium can be used in combination. In addition, a biaxial medium in which the refractive index in each direction satisfies nx> ny> nz, a negative C-Plate, or the like may be used.

  Further, a backlight (illuminating means) 60 having a light source, a reflector, a light guide plate, and the like is installed outside the counter substrate 20.

(Initial transition structure)
As described above, in the case of the OCB mode liquid crystal device, the liquid crystal when the power is shut off is in the splay alignment. Therefore, by applying a voltage higher than a certain threshold voltage to the liquid crystal when the power is turned on, the initial state shown in FIG. From this splay alignment, a so-called initial transition operation is required to transfer the alignment state of the liquid crystal to the bend alignment during the display operation shown in FIG. Here, if the initial transition is not sufficiently performed, display failure may occur or desired high-speed response may not be obtained.

  As an initial transfer operation, an appropriate rectangular voltage is applied to the scanning line 8 with a bias voltage applied to the data line 25 shown in FIG. The progress of the initial transition can be promoted by repeatedly applying and stopping the initial transition voltage for a predetermined time. In addition, if a disclination of liquid crystal molecules is generated in the dot region by applying an initial transition voltage, the disclination becomes a transition nucleus and the initial transition proceeds to the periphery. Thereby, the initial transition operation can be performed smoothly.

In this reference embodiment, in order to generate disclination in the dot region, an initial transition structure is formed in the inclined portion 70 of the liquid crystal layer thickness adjusting layer 24 shown in FIG. As an initial transition structure, slits and / or notches are formed in the strip electrode 25 disposed on the surface of the inclined portion 70. Further, as an initial transition structure, protrusions may be formed on or below the surface of the strip electrode 25 disposed on the surface of the inclined portion 70.

  FIG. 5 is a plan view of slits and / or notches that can be formed in the strip-shaped electrode of the inclined portion as the initial transition structure. As the slit and / or notch, one that generates oblique electric fields in various directions on the surface of the inclined portion by applying an initial transition voltage is formed. In FIG. 5A, a plurality of slits 71a bent repeatedly in a crank shape are formed. 5B and 5C, one or a plurality of spiral slits 71b are formed. In FIG. 5D, a bellows-like slit 71c and a notch 71d are formed. In FIG. 5 (e), a plurality of lightning-like slits 71e are formed. In addition, it is also possible to make a slit and / or a notch into shapes other than the above.

  In this way, if slits and / or notches bent in various directions are formed, oblique electric fields in various directions can be generated on the surface of the strip-shaped electrode in the inclined portion by applying the initial transition voltage. Become. Along with this, liquid crystal molecules having positive dielectric anisotropy try to reorient along the electric field direction while rotating in various directions. Thereby, disclination can be generated on the surface of the inclined portion. Then, by generating disclination in the inclined portions of all the dot areas, it is possible to initially transfer the alignment state of the liquid crystals in all the dot areas. Therefore, the initial transition operation can be performed smoothly.

  FIG. 6 is a plan view of a protrusion that can be formed on the surface of the inclined band-like electrode or under the band-like electrode as the initial transition structure. As the protrusions, those in which initial liquid crystal molecules are tilted and oriented in various directions and an oblique electric field in various directions is generated on the surface of the tilted portion by applying an initial transition voltage are formed. In FIG. 6A, a plurality of island-shaped protrusions 72a are formed on the surface of the belt-like electrode. The island-shaped protrusion 72a is formed with a height of 1.2 μm and a diameter of 10 μm, for example. In FIG. 6B, a plurality of lightning-like protrusions (projections) 72b are formed. Moreover, in FIG.6 (c), the linear protrusion 72c is formed in the width direction both ends. As a constituent material of these protrusions, it is possible to employ a novolac positive photoresist. By performing post-baking at about 220 ° C. after the development of the resist, a gentle protrusion shape can be obtained.

  By forming such protrusions, initial liquid crystal molecules can be tilted and aligned in various directions, and oblique electric fields in various directions are generated on the surface of the strip-shaped electrode in the inclined portion by applying an initial transition voltage. It becomes possible to make it. Along with this, liquid crystal molecules having positive dielectric anisotropy try to reorient along the electric field direction while rotating in various directions from various directions. Thereby, disclination can be generated on the surface of the inclined portion. Therefore, the initial transition operation can be performed smoothly.

  In addition, by forming the initial transition structure in the inclined portion 70 of the liquid crystal layer thickness adjusting layer 24 shown in FIG. 3A, the surface of the inclined portion 70 can be discriminated even during the display operation after the initial transition operation is completed. Nation may remain. However, in general, in the inclined portion of the liquid crystal layer thickness adjusting layer, liquid crystal molecules are inclined and an oblique electric field is generated, so that the alignment state is more easily disturbed than in the flat portion. That is, the inclined portion of the liquid crystal layer thickness adjusting layer does not contribute to improvement in display quality such as aperture ratio and contrast. Therefore, by providing an initial transition structure in the inclined portion 70 of the liquid crystal layer thickness adjustment layer 24, even if disclination remains around the initial transition structure, a decrease in display quality during display operation is minimized. be able to. By providing the initial transition structure in such an inclined portion 70, it becomes easier to generate disclination than in the case where the initial transition structure is provided in other portions.

(Second reference form)
Next, a liquid crystal device according to a second reference embodiment will be described with reference to FIGS.
The liquid crystal device according to the second reference embodiment is an active matrix type liquid crystal device that employs a thin film transistor (hereinafter referred to as “TFT”) element as a switching element, and therefore the first reference embodiment adopting a TFD element. Is different. Then, as shown by an arrow 19a in FIG. 9A, the alignment film is rubbed in a direction intersecting with the extending direction of the signal line, and is applied in parallel with the extending direction of the signal line. This is different from the first reference embodiment. Note that detailed description of portions having the same configuration as the first reference embodiment is omitted.

FIG. 7A is a plan view of the liquid crystal device as viewed from the counter substrate side together with each component, and FIG. 7B is a side sectional view taken along the line HH ′ of FIG.
As shown in FIG. 7, in the liquid crystal device 100 of this reference embodiment, TFT array substrate (hereinafter referred to as "device substrate".) And 10 and a counter substrate 20 are bonded together by a sealing material 52, defined by the sealant 52 A liquid crystal layer 50 is sealed in the region. In the peripheral circuit area outside the sealing material 52, a data signal driving circuit 101 and an external circuit mounting terminal 102 are formed along one side of the element substrate 10, and scanning signal driving is performed along two sides adjacent to the one side. A circuit 104 is formed. In addition, an inter-substrate conductive material 106 for providing electrical continuity between the element substrate 10 and the counter substrate 20 is disposed at a corner portion of the counter substrate 20.

(Equivalent circuit)
FIG. 8 is an equivalent circuit diagram of a liquid crystal device using TFT elements. In the image display area of the liquid crystal device, data lines 6a and gate lines 3a are arranged in a lattice pattern, and dots, which are image display units, are arranged in the vicinity of their intersections. Pixel electrodes 15 are respectively formed on the plurality of dots arranged in a matrix. A TFT element 13 which is a switching element for performing energization control to the pixel electrode 15 is formed on the side of the pixel electrode 15. A data line 6 a is electrically connected to the source of the TFT element 13. Image signals S1, S2,..., Sn are supplied to each data line 6a.

  A gate line (scanning line) 3 a is electrically connected to the gate of the TFT element 13. The gate lines 3a are supplied with scanning signals G1, G2,..., Gn in a pulsed manner at a predetermined timing. The pixel electrode 15 is electrically connected to the drain of the TFT element 13. When the TFT element 13 serving as a switching element is turned on for a certain period by the scanning signals G1, G2,..., Gn supplied from the gate line 3a, the image signals S1, S2,. , Sn are written to the liquid crystal of each pixel at a predetermined timing.

  Image signals S1, S2,..., Sn written at a predetermined level on the liquid crystal are held for a certain period by a liquid crystal capacitor formed between the pixel electrode 15 and a common electrode described later. In order to prevent leakage of the held image signals S1, S2,..., Sn, a storage capacitor 7 is formed between the pixel electrode 15 and the capacitor line 3b, and is arranged in parallel with the liquid crystal capacitor. . When a voltage signal is applied to the liquid crystal as described above, the alignment state of the liquid crystal molecules changes according to the applied voltage level. As a result, light incident on the liquid crystal is modulated to enable gradation display.

(Planar structure, cross-sectional structure)
Figure 9 is an explanatory view of a liquid crystal device according to a second referential embodiment, FIG. 9 (a) is a plan view taken along line F-F of FIG. 9 (b), FIG. 9 (b) Fig. 9 (a It is sectional drawing which follows the EE line | wire of (). As shown in FIG. 9 (b), the liquid crystal device 100 of this reference embodiment includes an element substrate 10 disposed on the light source side, a counter substrate 20 which are disposed on the viewer's side, the element substrate 10 and the counter substrate 20 The sandwiched liquid crystal layer 50, a reflection film (reflection electrode) 15r that is provided on the element substrate 10 side and reflects light incident from the counter substrate 20 side, and the liquid crystal layer 50 in the reflection display region R where the reflection film 15r exists. Is a transflective liquid crystal device having a liquid crystal layer thickness adjusting layer 24 for making the thickness of the liquid crystal layer 50 smaller than the thickness of the liquid crystal layer 50 in the transmissive display region T where the reflective film 15r does not exist.

  As shown in FIG. 9A, the data line 6a described above is arranged along the longitudinal direction of the rectangular pixel electrode 15, and the gate line 3a and the capacitor line 3b described above along the short direction of the pixel electrode 15. Is arranged. A TFT element 13 is formed near the intersection of the data line 6a and the gate line 3a. The drain of the TFT element 13 is connected to the pixel electrode 15 through the contact hole 14.

  As shown in FIG. 9B, the element forming layer 12 including the above-described data line, gate line, capacitor line, TFT element and the like is disposed inside the substrate body 11 of the element substrate 10. Inside the element forming layer 12, a resin layer 16 having irregularities on the surface is formed at one end in the longitudinal direction of a dot region serving as an image display unit. A reflective electrode (reflective film) 15r made of a highly reflective metal material such as Al or Ag is formed on the surface of the resin layer 16. A transparent electrode 15t made of a transparent conductive material such as ITO is formed on the remaining portion of the dot region in the longitudinal direction. The reflective electrode 15r and the transparent electrode 15t are conductively connected to form the pixel electrode 15. The formation area of the reflective electrode 15r is the reflective display area R, and the formation area of the transparent electrode 15t is the transmissive display area T.

On the other hand, a CF layer 22 is formed inside the substrate body 21 of the counter substrate 20. The CF layer 22 may be formed on the element substrate 10. Inside the CF layer 22, a liquid crystal layer thickness adjusting layer 24 for making the thickness of the liquid crystal layer 50 in the reflective display region R smaller than the thickness of the liquid crystal layer 50 in the transmissive display region T is provided. In addition, an inclined portion 70 of the liquid crystal layer thickness adjusting layer 24 is formed in a boundary region between the reflective display region R and the transmissive display region T. In general, in the inclined portion 70 of the liquid crystal layer thickness adjusting layer 24, the alignment state of the liquid crystal molecules is likely to be disturbed, and the display quality is likely to be deteriorated.
Therefore, the liquid crystal device according to the second reference embodiment has a configuration in which the transmissive display is emphasized by arranging the inclined portion 70 in the reflective display region R. The liquid crystal layer thickness adjusting layer 24 may be provided on the element substrate 10 or on both the element substrate 10 and the counter substrate 20. A common electrode 25 is formed on substantially the entire inner surface of the counter substrate 20 on which the liquid crystal layer thickness adjusting layer 24 is formed.

  An alignment film 29 made of polyimide or the like is formed on the surface of the common electrode 25. An alignment film 19 made of polyimide or the like is also formed on the surface of the pixel electrode 15 formed on the element substrate 10. The alignment films 19 and 29 are rubbed. The rubbing process is performed in a direction intersecting with the extending direction of the data line 6a (that is, the longitudinal direction of the pixel electrode 15) as indicated by an arrow 19a in FIG.

As shown in FIG. 9B, a liquid crystal layer 50 that operates in the OCB mode is sandwiched between the element substrate 10 and the counter substrate 20. In this preferred embodiment, the transmissive display region T and the reflective display region R together horizontal alignment film is formed, the liquid crystal layer 50 in the transmissive display region T and the reflective display region R, is adapted to operate in both OCB mode.
In addition, a photo spacer 59 is formed in order to regulate the thickness (cell gap) of the liquid crystal layer 50.

(Initial transition structure)
As an initial transition operation in the second reference embodiment, a pulse voltage of about 15 V is applied between the pixel electrode 15 and the common electrode 25 while the gate lines are turned on line-sequentially. If the disclination is generated in the dot area by applying the initial transition voltage, the initial transition operation can be performed smoothly. Therefore, also in the second reference embodiment, an initial transition structure is formed in the inclined portion 70 of the liquid crystal layer thickness adjusting layer 24.

  As an initial transition structure, slits and / or notches are formed in the common electrode 25 of the inclined portion 70 shown in FIG. As the slits and / or notches, those which generate oblique electric fields in various directions on the surface of the inclined portion 70 by applying an initial transition voltage are formed. Specifically, as shown in FIG. 5, slits and / or notches bent in various directions may be formed. Thereby, it is possible to generate disclination on the surface of the inclined portion, and the initial transfer operation can be performed smoothly.

Further, as an initial transition structure, a protrusion may be formed on the surface of the common electrode 25 of the inclined portion 70 shown in FIG. As the protrusions, those in which initial liquid crystal molecules are tilted and oriented in various directions and an oblique electric field in various directions is generated on the surface of the inclined portion 70 by application of an initial transition voltage are formed. Specifically, as shown in FIG. 6, the same protrusions as those in the first reference embodiment may be formed. Thereby, disclination can be generated on the surface of the inclined portion.
Then, by generating disclination in the inclined portions of all the dot areas, it becomes possible to transfer the alignment state of the liquid crystals in all the dot areas. Therefore, the initial transition operation can be performed smoothly.

Further, as shown in FIG. 9A, in the second reference embodiment, the alignment film is rubbed in the direction intersecting the extending direction of the signal lines such as the data lines (the direction of the arrow 19a). The liquid crystal molecules before application of the initial transition voltage are aligned along the rubbing direction. When the initial transition voltage is applied to the data line, a lateral electric field is generated along the short direction of the pixel electrode. In addition to the oblique electric field due to the initial transition structure, liquid crystal molecules having positive dielectric anisotropy tend to be reoriented while rotating in more various directions due to the influence of the transverse electric field. Thereby, it becomes easy to generate disclination on the surface of the inclined portion, and the initial transition operation can be performed more smoothly. For example, the initial transition can be completed in 200 ms or less.

In the second reference embodiment, as shown in FIG. 9B, the light shielding film 23 is formed inside the CF layer 22 that planarly overlaps the inclined portion 70 of the liquid crystal layer thickness adjusting layer 24. According to this configuration, even when disclination remains around the initial transition structure during display operation after the initial transition operation is completed, it is possible to prevent light leakage due to the disclination. . Thereby, it is possible to prevent the display quality from being lowered during the display operation.

(3rd reference form)
Next, a liquid crystal device according to a third reference embodiment will be described with reference to FIG.
10 (a) and 10 (b) are side cross-sectional views of the portion corresponding to the line EE in FIG. 9 (a). In FIG. 10, only the functional layer adjacent to the liquid crystal layer 50 is shown for easy understanding. The liquid crystal device 100 according to the third reference embodiment operates in both the transmissive display area T and the reflective display area R in the OCB mode in that the transmissive display area T operates in the OCB mode and the reflective display area R operates in the R-OCB mode. This is different from the second reference embodiment. Note that detailed description of portions having the same configuration as each of the reference embodiments is omitted.

  In the liquid crystal device shown in FIG. 10A, the horizontal alignment film 29 is formed on the entire inner side of the counter substrate 20, whereas the horizontal alignment film 19t is formed in the transmissive display region T on the inner side of the element substrate 10. The vertical alignment film 19r is formed in the reflective display region R. In order to form the alignment film 19, first, a vertical alignment film is formed on the entire inner side of the element substrate 10. Next, ultraviolet rays are irradiated from the outside of the element substrate 10. At this time, the alignment film 19t in the transmissive display region T is changed to a horizontal alignment film by irradiating only the transmissive display region T with ultraviolet rays using the reflective film 15r as a mask. Further, by forming a horizontal alignment film on the entire inner side of the element substrate 10 and selectively performing an optical alignment process on the reflective display region R, the alignment film 19r in the reflective display region R is changed to a vertical alignment film. Also good.

  In this case, the liquid crystal layer 50 in the transmissive display region T operates in the OCB mode because the horizontal alignment films 19t and 29 are formed on both substrates. On the other hand, in the reflective display region R, since the horizontal alignment film 29 is formed on the counter substrate 20 and the vertical alignment film 19r is formed on the element substrate 10, the alignment state of liquid crystal molecules from the counter substrate 20 to the element substrate 10 is achieved. Changes from horizontal alignment to vertical alignment. That is, it is a hybrid-aligned nematic (HAN) in which the tilt angle of the liquid crystal molecules changes continuously. Thereby, the liquid crystal layer 50 in the reflective display region R operates in the R-OCB mode. The alignment state of the R-OCB mode corresponds to the upper half or the lower half of the bend alignment in the OCB mode. Therefore, high-speed response of display operation is realized by modulating the transmittance with the degree of bending of the bend alignment. can do. Moreover, unlike the OCB mode, the display operation can be started without going through the initial transition operation.

  On the other hand, in the liquid crystal device shown in FIG. 10B, the horizontal alignment film 19 is formed on the entire inner side of the element substrate 10, whereas the horizontal alignment film is formed in the transmissive display region T on the inner side of the counter substrate 20. 29t is formed, and a vertical alignment film 29r is formed in the reflective display region R. Also in this case, the transmissive display area T operates in the OCB mode, whereas the reflective display area R operates in the R-OCB mode. However, in the reflective display region R of the liquid crystal device shown in FIG. 10B, the alignment state of the liquid crystal molecules changes from the horizontal alignment to the vertical alignment from the element substrate 10 to the counter substrate 20, contrary to the case of FIG. The hybrid orientation is changing.

Also in the third reference embodiment, the initial transition structure is provided in the inclined portion 70 of the liquid crystal layer thickness adjusting layer 24. Thus, the initial transition operation of the transmissive display area that operates in the OCB mode can be smoothly performed.

In the third reference embodiment, since the transmissive display area T operates in the OCB mode and the reflective display area operates in the R-OCB mode, a horizontal alignment film is formed in the transmissive display area on the element substrate or the counter substrate. It is necessary to form a vertical alignment film. On the other hand, in the first and second reference embodiments, the liquid crystal layers 50 in the transmissive display area T and the reflective display area R both operate in the OCB mode, so that the alignment between the transmissive display area T and the reflective display area R is achieved. There is no need to make separate membranes.

(Fourth embodiment)
Next, a liquid crystal device according to a fourth embodiment will be described with reference to FIG.
11A and 11B are explanatory views of the liquid crystal device according to the fourth embodiment. FIG. 11A is a plan view taken along the line NN in FIG. 11B, and FIG. It is sectional drawing which follows the MM line | wire of (). As shown in FIG. 11B, the liquid crystal device 100 according to the fourth embodiment has dots in that the gate line 3a is arranged so as to overlap the inclined portion 70 of the liquid crystal layer thickness adjusting layer 24 in a plane. It is different from the second referential embodiment the gate line is disposed outside the region. Note that detailed description of portions having the same configuration as each of the reference embodiments is omitted.

As shown in FIG. 11B, in the fourth embodiment, a liquid crystal layer thickness adjusting layer 24 is provided on the element substrate 10. An initial transition structure is provided in the inclined portion 70 of the liquid crystal layer thickness adjusting layer 24. Further, the gate line 3 a is arranged on the element formation layer 12 in the element substrate 10 so as to overlap the inclined portion 70 in a plan view.
As shown in FIG. 11A, the gate line 3 a is disposed so as to cross the pixel electrode 15. A notch portion of the pixel electrode 15 is formed near the intersection of the gate line 3a and the data line 6a, and a TFT element 13 is formed in the notch portion. The drain of the TFT element 13 is connected to the pixel electrode 15 through the contact hole 14.

  As shown in FIG. 11B, the capacitor line 3b may be arranged outside the reflective film 17 along with the gate line 3a, and a storage capacitor may be formed between the capacitor line 3b and the reflective film 17. In this case, as viewed from the observer of the liquid crystal device 100, the capacitance line 3b can be concealed on the back surface of the reflective film 17, so that a decrease in the aperture ratio due to the presence of the capacitance line 3b can be prevented.

  When the gate line 3 a arranged as described above is turned on, an electric field generated around the gate line 3 a reaches the inclined portion 70. Due to the influence of this electric field, the liquid crystal molecules having positive dielectric anisotropy tend to be reoriented while rotating in more various directions. Thereby, it becomes easy to generate disclination on the surface of the inclined portion 70, and the initial transfer operation can be performed more smoothly.

  In addition, since the gate line 3a is arranged so as to overlap the inclined portion 70 of the liquid crystal layer thickness adjusting layer 24, disclination is generated around the initial transition structure in the display operation after the initial transition operation is completed. Even if it remains, light leakage due to the disclination can be prevented. Thereby, it is possible to prevent a decrease in contrast during the display operation.

(Electronics)
FIG. 12 is a perspective view showing an example of an electronic apparatus according to the present invention. A cellular phone 1300 illustrated in FIG. 12 includes the liquid crystal device of the present invention as a small-sized display portion 1301, and includes a plurality of operation buttons 1302, an earpiece 1303, and a mouthpiece 1304. Since the liquid crystal device of the present invention can smoothly perform the initial transition operation in the OCB mode while minimizing the deterioration in display quality, the mobile phone 1300 with excellent display quality can be provided.

  The display device of each of the above embodiments is not limited to the mobile phone, but is an electronic book, a personal computer, a digital still camera, a liquid crystal television, a viewfinder type or a monitor direct view type video tape recorder, a car navigation device, a pager, and an electronic notebook. , Calculators, word processors, workstations, videophones, POS terminals, devices equipped with touch panels, etc., can be suitably used as image display means, and any electronic device can display bright and high-contrast images. Yes.

  The technical scope of the present invention is not limited to the above-described embodiments, and includes various modifications made to the above-described embodiments without departing from the spirit of the present invention. That is, the specific materials and configurations described in the embodiments are merely examples, and can be changed as appropriate.

It is an equivalent circuit diagram of a liquid crystal device using a TFD element. It is a fragmentary perspective view of the display area of the liquid crystal device using a TFD element. It is explanatory drawing of the liquid crystal device which concerns on a 1st reference form. It is explanatory drawing of the orientation state of the liquid crystal molecule in the liquid crystal device of OCB mode. It is a top view of the slit and notch which can be formed as an initial stage transition structure. It is a top view of the protrusion which can be formed as an initial stage transition structure. It is the top view and side sectional drawing of a liquid crystal device. It is an equivalent circuit diagram of a liquid crystal device using a TFT element. It is explanatory drawing of the liquid crystal device which concerns on a 2nd reference form. It is explanatory drawing of the liquid crystal device which concerns on a 3rd reference form. It is explanatory drawing of the liquid crystal device which concerns on 4th Embodiment. It is a perspective view of a mobile phone.

Explanation of symbols

  R ... Reflection display area T ... Transmission display area 3a ... Signal line 10 ... Element substrate 20 ... Counter substrate 23 ... Light-shielding film 24 ... Liquid crystal layer thickness adjustment layer 25 ... Electrode 50 ... Liquid crystal layer 70 ... Inclined part 71 ... Slit 72 ... Projection 100 Liquid crystal device

Claims (8)

A pair of substrates arranged opposite to each other and sandwiching the liquid crystal layer, an alignment film disposed on the pair of substrates, and a voltage applied to the liquid crystal layer disposed in a matrix on one of the pair of substrates. An electrode to be applied, a switching element that controls energization to the electrode, a scanning line that supplies a scanning signal to the switching element, and a data line that is arranged to intersect the scanning line and supplies an image signal a reflective film which reflects light incident from the substrate side of the other is provided in the substrate of one of said pair of substrates, the thickness of the liquid crystal layer in the transmissive display region the thickness of the liquid crystal layer in the reflective display region And a liquid crystal layer thickness adjusting layer that makes the retardation of the liquid crystal layer substantially the same in the reflective display region and the transmissive display region ,
An operation mode of the liquid crystal layer in at least the transmissive display region is an OCB mode,
An initial transition structure of the liquid crystal layer is provided in a formation region of the inclined portion of the liquid crystal layer thickness adjusting layer provided between the reflective display region and the transmissive display region ,
The scanning line is arranged in a region overlapping the inclined portion in a plane,
The liquid crystal device , wherein the alignment film is rubbed in a direction crossing the data line .   The liquid crystal device according to claim 1, wherein an operation mode of the liquid crystal layer in the reflective display region is an OCB mode.   The liquid crystal device according to claim 1, wherein an operation mode of the liquid crystal layer in the reflective display region is an R-OCB mode. The initial transition structure, the liquid crystal device according to any one of claims 1 to 3, characterized in that it lacks before Symbol collector slits and / or cut formed in the electrode. The initial transition structure, the liquid crystal device according to any one of claims 1 to 3, characterized in that a projection formed below the previous SL conductive surface of electrode or the electrode.   The liquid crystal device according to claim 1, wherein the inclined portion is provided in the reflective display region.   The liquid crystal device according to claim 1, wherein the inclined portion is provided in the transmissive display area. An electronic apparatus comprising the liquid crystal device according to any one of claims 1 to 7.

Images