JP4042758B2 - Liquid crystal device and electronic device - Google Patents

Description

  The present invention relates to a liquid crystal device such as a passive matrix driving method and an electronic apparatus using the same. Specifically, the present invention relates to an internal reflection type reflective liquid crystal device or a transflective liquid crystal device in which a reflective layer or a transflective layer is provided on the liquid crystal surface side of a substrate, and an electronic device using such a liquid crystal device Regarding equipment.

  Conventionally, reflective liquid crystal devices that display using external light without using a light source such as a backlight are advantageous from the viewpoint of low power consumption, small size, and light weight. It is used in portable electronic devices such as mobile phones, wristwatches, electronic notebooks, and notebook computers. In a traditional reflective liquid crystal device, a liquid crystal is sandwiched between a pair of substrates, and external light incident from the front side via a liquid crystal panel, a polarizing plate, etc. is pasted on the back side of the liquid crystal panel It is the structure which reflects by. However, in this case, since the optical path from the liquid crystal separated by the substrate or the like to the reflector is long, parallax occurs in the display image, resulting in a double image, and in the case of color display, each color light is transmitted by the long optical path described above. Therefore, it is very difficult to display a high-quality image. In addition, since the external light is attenuated during reciprocation between the light incident on the liquid crystal panel and the reflector, it is basically difficult to perform bright display.

  Therefore, recently, an internal reflection type reflection type in which the reflection position is brought close to the liquid crystal layer by also using the display electrode formed on the substrate located on the opposite side to the side on which the external light is incident as a reflection plate. Liquid crystal devices have been developed. Specifically, Japanese Patent Application Laid-Open No. 8-114799 discloses a technique for forming a pixel electrode that also serves as a reflector on a substrate.

  On the other hand, in the reflective liquid crystal device, since the display can be visually recognized by using external light, the display cannot be read in a dark place. For this reason, a transflective liquid crystal device in which external light is used in a bright place in the same manner as a normal reflective liquid crystal device, while a display can be visually recognized by an internal light source in a dark place is disclosed in Japanese Utility Model Laid-Open No. 57-049271. And JP-A-8-292413.

  However, according to these, a transflective plate, a backlight, etc. are disposed on the outer surface of the liquid crystal panel opposite to the observation side, and a transparent substrate is interposed between the liquid crystal layer and the transflective plate. As a result, double reflections and display blurring occur. Further, when a color filter is combined, there is a problem in that a double image or blurring of display occurs due to parallax, and sufficient color development cannot be obtained. Japanese Patent Application Laid-Open No. 7-318929 proposes a transflective liquid crystal device in which a pixel electrode serving also as a transflective film is provided on the inner surface of a liquid crystal cell.

  However, according to the reflection type liquid crystal device described in JP-A-8-114799, it is extremely difficult to simultaneously increase the brightness and contrast ratio. Particularly in the case of color display, if one or more retardation plates (phase difference films) are used for color correction, it is more difficult to increase the brightness and contrast ratio and at the same time accurately perform color correction. There is a problem of becoming.

  On the other hand, according to the transflective liquid crystal device described in Japanese Patent Application Laid-Open No. 7-318929, it is extremely difficult to simultaneously increase the brightness and contrast ratio during the reflective display. Particularly in the case of color display, if one or more retardation plates are used for color correction, it is more difficult to increase the brightness and contrast ratio and accurately perform color correction at the time of reflective display. There is a problem.

  Incidentally, the applicant of the present application has proposed a novel transflective liquid crystal device in Japanese Patent Application No. 10-160866. However, this liquid crystal device can obtain a sufficient reflectance particularly in the reflective display. There is a problem that the display becomes dark.

  The present invention has been made in view of the above-described problems, and both the brightness and the contrast ratio are enhanced, and the reflection type liquid crystal device suitable for color display, in particular, the brightness and the contrast ratio at the time of the reflection type display. It is a technical problem to provide a transflective liquid crystal device that is both enhanced and suitable for color display, and an electronic device including the liquid crystal device including such a reflective or transflective liquid crystal device. To do.

In order to solve the above technical problem, a first liquid crystal device of the present invention is sandwiched between a first substrate, a transparent second substrate disposed opposite to the first substrate, and the first and second substrates. Liquid crystal, a reflective electrode layer disposed on the side of the first substrate facing the second substrate, a polarizing plate provided on the opposite side of the second substrate to the first substrate, and the polarizing plate And a second retardation plate disposed between the polarizing plate and the first retardation plate, and a plurality of pixels. The surface of the reflective electrode layer has irregularities, the layer thickness of the liquid crystal layer is not constant within the pixel, the twist angle of the liquid crystal is 230 to 260 degrees, and Δnd (optically anisotropic) of the liquid crystal Product Δn and layer thickness d) has a minimum value of 0.85 μm or less and a maximum value of 0.70 μm or more, Δnd of one retardation plate is 150 ± 50 nm, Δnd of the second retardation plate is 610 ± 60 nm, and the transmission axis or absorption axis of the polarizing plate and the optical axis of the second retardation plate Is an angle θ1 of 10 to 35 degrees, and an angle θ2 between an optical axis of the first retardation plate and an optical axis of the second retardation plate is 30 to 60 degrees. .

According to the first liquid crystal device of the present invention, the external light incident from the polarizing plate side is reflected by the reflective electrode layer provided on the first substrate via the polarizing plate, the transparent second substrate, and the liquid crystal. Then, the light is emitted again from the side of the polarizing plate through the liquid crystal, the second substrate, and the polarizing plate. Therefore, for example, by controlling the alignment state of the liquid crystal using the electric field between the reflective electrode layer (reflective electrode) provided on the first substrate and the transparent electrode (counter electrode) provided on the second substrate. The intensity of external light emitted as display light via the liquid crystal after reflection by the reflective electrode layer can be controlled. As described above, the presence of the transparent substrate between the liquid crystal and the reflective plate prevents the occurrence of double reflection or display blur, and sufficient color development can be obtained even when the color is changed. Then, by using two retardation plates called first and second retardation plates disposed between the polarizing plate and the second substrate, color correction can be performed relatively easily and accurately. Note that the reflective electrode layer refers to a single-layer or multilayer film having both a reflection function and an electrode function. The surface of the reflective electrode layer has irregularities. Since the external light reflected through the liquid crystal is reflected by the reflective electrode layer formed in a concavo-convex shape, it is possible to obtain optimum reflection characteristics by controlling the size and shape of the concavo-convex shape. Therefore, brighter and higher quality display can be performed.

  Here, since the twist angle of the liquid crystal is 230 to 260 degrees, a high contrast ratio such as “10” or more can be realized. At the same time, Δnd of the liquid crystal has a minimum value of 0.85 μm or less and a maximum value of 0.70 μm or more. Therefore, the Δnd of the liquid crystal device with respect to the applied voltage of the liquid crystal device in a relatively wide operating temperature range required by the device specifications. The change in transmittance can be monotonous (that is, monotonically increased or monotonically decreased), and gradation display can be performed accurately.

  Further, in the first liquid crystal device, Δnd of the first retardation plate is 150 ± 50 nm (that is, 100 to 200 nm), and Δnd of the second retardation plate is 610 ± 60 nm (that is, 550 to 670 nm). Therefore, it is possible to effectively avoid a situation in which the black display is reddish or bluish. In addition to these, since the angle θ1 is 10 to 35 degrees and the angle θ2 is 30 to 60 degrees, the brightness and contrast ratio can be increased at the same time, and two retardation plates are used. As a result, a high-quality reflective display in which color correction is accurately performed during color display or monochrome display is possible.

  In one aspect of the first liquid crystal device of the present invention, Δnd of the liquid crystal is 0.70 to 0.85 μm.

  According to this aspect, the Δnd of the liquid crystal is 0.70 to 0.85 μm (that is, the minimum value of Δnd of the liquid crystal is 0.70 μm or more and the maximum value of Δnd of the liquid crystal is 0.85 μm or less. Therefore, the change in the transmittance with respect to the applied voltage of the liquid crystal device can be made better monotonously in a wide operating temperature range required for the device specifications, and gradation display can be performed very accurately. It becomes possible.

  Particularly in the first liquid crystal device of the present invention, the Δnd of the liquid crystal is 0.70 to 0.85 μm as long as the layer thickness d of the liquid crystal is constant in the image display region or the opening region of each pixel. Under the conditions, a very good result (that is, the above-mentioned good change in transmittance and gradation display) can be obtained. However, for example, in the case where irregularities are consciously or unconsciously formed on the surface of the reflective electrode layer and the layer thickness d of the liquid crystal is not constant in all regions in each pixel, the liquid crystal It may be difficult or impossible to set the range of Δnd to 0.70 to 0.85 μm in all regions in each pixel. In such a case, as described above, if Δnd of the liquid crystal is set such that the minimum value is 0.85 μm or less and the maximum value is 0.70 μm or more, a sufficiently satisfactory result for practical use. (In other words, the above-described good transmittance change and gradation display) can be obtained.

  In another aspect of the first liquid crystal device of the present invention, a color filter is provided on the liquid crystal side surface of the first substrate or the second substrate.

  According to this aspect, by controlling the alignment state of the liquid crystal using the reflective electrode layer, it is possible to control the intensity of external light emitted as display light through the liquid crystal after reflection by the reflective electrode layer. Since the reflected light is reflected through the color filter, a color reflective display is possible. At this time, color correction can be performed relatively easily and accurately by using two retardation plates arranged between the polarizing plate and the second substrate. As a result, the brightness and contrast ratio can be increased at the same time, and a high-quality color reflective display with high color reproducibility can be realized.

  In another aspect of the first liquid crystal device of the present invention, the reflective electrode layer comprises a single-layer reflective electrode.

  According to this aspect, by controlling the alignment state of the liquid crystal using the reflective electrode provided on the first substrate, the intensity of external light emitted as display light via the liquid crystal after reflection by the reflective electrode can be controlled. In addition, what is necessary is just to form such a reflective electrode from metal films, such as Al (aluminum), for example.

  Alternatively, in another aspect of the first liquid crystal device of the present invention, the reflective electrode layer includes a reflective film, a transparent insulating film disposed on the reflective film, and a transparent electrode disposed on the insulating film. It has the laminated structure containing.

  According to this aspect, by controlling the alignment state of the liquid crystal using the transparent electrode laminated on the first substrate, it is possible to control the intensity of external light emitted as display light through the liquid crystal after reflection by the reflective film. Such a transparent electrode may be formed of, for example, an ITO (Indium Tin Oxide) film, and the insulating film may be formed of, for example, silicon oxide as a main component. On the other hand, the reflective film may be formed of a metal film such as Al.

  In another aspect of the first liquid crystal device of the present invention, passive matrix driving is performed in a normally black mode.

  According to this aspect, for example, a normally black mode passive matrix drive method using STN liquid crystal has a high brightness and contrast ratio, and a high-quality reflective type in which color correction is accurately performed during color display. Display is possible.

  In another aspect of the first liquid crystal device of the present invention, irregularities are formed on the surface of the first substrate facing the second substrate.

  According to this aspect, the external light reflected through the liquid crystal is reflected by the reflective electrode layer formed in an uneven shape by being formed on the uneven surface of the substrate. It is possible to obtain optimum reflection characteristics by controlling. Therefore, finally, brighter and higher quality display can be performed. In addition, as a formation method of such an unevenness | corrugation, the method of forming the surface of a 1st board | substrate in uneven | corrugated shape may be used, for example, and the method of forming an uneven | corrugated film | membrane on the surface on a flat 1st substrate may be sufficient. Further, the reflective electrode layer itself can be formed in an uneven shape on the flat first substrate.

In order to solve the above technical problem, a second liquid crystal device of the present invention is sandwiched between a first substrate, a transparent second substrate disposed opposite to the first substrate, and the first and second substrates. A liquid crystal, a transflective electrode layer disposed on a side of the first substrate facing the second substrate, a polarizing plate provided on a side of the second substrate opposite to the first substrate, A first retardation plate disposed between a polarizing plate and the second substrate; a second retardation plate disposed between the polarizing plate and the first retardation plate; and a plurality of pixels. The surface of the reflective electrode layer has irregularities, the layer thickness of the liquid crystal layer is not constant within the pixel, the twist angle of the liquid crystal is 230 to 260 degrees, and Δnd (optical The product of anisotropy Δn and layer thickness d) has a minimum value of 0.85 μm or less and a maximum value of 0.70 μm or more Δnd of the first retardation plate is 150 ± 50 nm, Δnd of the second retardation plate is 610 ± 60 nm, and the transmission axis or absorption axis of the polarizing plate and the light of the second retardation plate The angle θ1 formed by the axis is 10 to 35 degrees, and the angle θ2 formed by the optical axis of the first phase difference plate and the optical axis of the second phase difference plate is 30 to 60 degrees. And

According to the second liquid crystal device of the present invention, the external light incident from the polarizing plate side is provided on the first substrate through the polarizing plate, the transparent second substrate, and the liquid crystal during the reflective display. The light is reflected by the transflective electrode layer, and is emitted from the polarizing plate side again through the liquid crystal, the second substrate, and the polarizing plate. Therefore, for example, the alignment state of the liquid crystal is changed using the electric field between the transflective electrode layer (semi-transmissive reflective electrode) provided on the first substrate and the transparent electrode (counter electrode) provided on the second substrate. By controlling, it is possible to control the intensity of external light emitted as display light through the liquid crystal after reflection by the semi-transmissive reflective electrode layer. As described above, the presence of the transparent substrate between the liquid crystal and the reflecting plate does not cause double reflection or display blur, and sufficient color development can be obtained even when the color is changed. Then, by using two retardation plates called first and second retardation plates disposed between the polarizing plate and the second substrate, color correction can be performed relatively easily and accurately. The transflective electrode layer refers to a single layer or multilayer film having a transflective function and an electrode function. The surface of the reflective electrode layer has irregularities. Since the external light reflected through the liquid crystal is reflected by the reflective electrode layer formed in a concavo-convex shape, it is possible to obtain optimum reflection characteristics by controlling the size and shape of the concavo-convex shape. Therefore, brighter and higher quality display can be performed.

  On the other hand, during transmissive display, the light source light emitted from the light source and transmitted from the first substrate side through the transmissive region of the semi-transmissive reflective electrode layer is emitted from the polarizing plate side through the liquid crystal, the second substrate, and the polarizing plate. . Therefore, for example, if another polarizing plate is disposed between the first substrate and the light source so that the transmission axis and the absorption axis are in a predetermined relationship with the polarizing plate on the second substrate, the first substrate and the light source have a predetermined relationship. By controlling the alignment state of the liquid crystal using an electric field between the provided semi-transmissive reflective electrode layer (semi-transmissive reflective electrode) and the transparent electrode (counter electrode) provided on the second substrate, semi-transmissive reflection The intensity of the light source emitted as display light through the liquid crystal after passing through the electrode layer can be controlled.

  Here, since the twist angle of the liquid crystal is 230 to 260 degrees, a high contrast ratio of, for example, “10” or more can be realized. At the same time, Δnd of the liquid crystal has a minimum value of 0.85 μm or less and a maximum value of 0.70 μm or more. Therefore, the Δnd of the liquid crystal device with respect to the applied voltage of the liquid crystal device in a relatively wide operating temperature range required by the device specifications. The change in transmittance can be monotonous (that is, monotonically increased or monotonically decreased), and gradation display can be performed accurately.

  In the second liquid crystal device, Δnd of the first retardation plate is 150 ± 50 nm (that is, 100 to 200 nm), and Δnd of the second retardation plate is 610 ± 60 nm (that is, 550 to 670 nm). Therefore, it is possible to effectively avoid a situation in which the black display is reddish or bluish. In addition to these, since the angle θ1 is 10 to 35 degrees and the angle θ2 is 30 to 60 degrees, the brightness and contrast ratio can be increased at the same time, and two retardation plates are used. As a result, it is possible to display a high-quality display in which color correction is accurately performed during color display or monochrome display.

  In one aspect of the second liquid crystal device of the present invention, Δnd of the liquid crystal is 0.70 to 0.85 μm.

  According to this aspect, the Δnd of the liquid crystal is 0.70 to 0.85 μm (that is, the minimum value of Δnd of the liquid crystal is 0.70 μm or more and the maximum value of Δnd of the liquid crystal is 0.85 μm or less. Therefore, the change in the transmittance with respect to the applied voltage of the liquid crystal device can be made better monotonously in a wide operating temperature range required for the device specifications, and gradation display can be performed very accurately. It becomes possible.

  Particularly in the second liquid crystal device of the present invention, the Δnd of the liquid crystal is 0.70 to 0.85 μm as long as the liquid crystal layer thickness d is constant in the image display region or the opening region of each pixel. Under certain conditions, very good results are obtained. However, when the layer thickness d of the liquid crystal is not constant in all the regions in each pixel, the range of Δnd of the liquid crystal is 0.70 to 0.85 μm in all the regions in each pixel. Can be difficult or impossible. In such a case, as described above, if Δnd of the liquid crystal is set such that the minimum value is 0.85 μm or less and the maximum value is 0.70 μm or more, a sufficiently satisfactory result for practical use. Is obtained.

  In another aspect of the second liquid crystal device of the present invention, a color filter is provided on the liquid crystal side surface of the first substrate or the second substrate.

  According to this aspect, at the time of reflection type display, by controlling the alignment state of the liquid crystal using the transflective electrode layer provided on the first substrate, the display is performed via the liquid crystal after reflection by the transflective electrode layer. The intensity of external light emitted as light can be controlled. Since the reflected light is reflected through the color filter, a color reflective display is possible. On the other hand, at the time of transmissive display, the alignment state of the liquid crystal is controlled by using the semi-transmissive reflective electrode layer provided on the first substrate, and then emitted as display light through the liquid crystal after being transmitted through the semi-transmissive reflective electrode layer. The light source light intensity can be controlled. Since the light source light is emitted through the color filter, a color transmissive display is possible. As a result, the brightness and contrast ratio can be increased at the same time, and high-quality color display with high color reproducibility can be achieved.

  In another aspect of the second liquid crystal device of the present invention, the transflective electrode layer is formed of a reflective layer in which a slit is formed.

  According to this aspect, by controlling the alignment state of the liquid crystal using the reflective layer provided with the slit provided on the first substrate, the display light is reflected via the liquid crystal after reflection by the reflective electrode in the reflective display. In the transmissive display, the intensity of the light source emitted as display light through the liquid crystal after passing through the slit can be controlled. In addition, what is necessary is just to form such a reflective electrode from metal films, such as Al. Further, as the transflective electrode layer, in addition to the reflective layer in which such slits are formed, for example, the gap is separated from each other when viewed in plan from a direction perpendicular to the second substrate so that light can pass through the gap. Alternatively, the reflective layer may be a reflective layer provided with a plurality of regular or irregular openings that can transmit light.

  In this aspect, the slit may have a width of 3 to 20 μm.

  With this configuration, a bright and high-contrast display is possible during both the reflective display and the transmissive display.

  Alternatively, in another aspect of the second liquid crystal device of the present invention, the transflective electrode layer includes a transflective film, a transparent insulating film disposed on the transflective film, and an insulating film on the insulating film. It has a laminated structure including transparent electrodes arranged.

  According to this aspect, by controlling the alignment state of the liquid crystal using the transparent electrode laminated on the semi-transmissive reflective film on the first substrate, at the time of reflective display, the liquid crystal is transmitted after reflection by the semi-transmissive reflective film. The intensity of external light emitted as display light can be controlled, and in the case of transmissive display, the intensity of light source emitted as display light after passing through the transflective film and the transparent electrode can be controlled. Such a transparent electrode may be formed of, for example, an ITO film, and the insulating film may be formed of, for example, silicon oxide as a main component. On the other hand, such a transflective film may be formed of a metal film such as Al provided with slits and openings.

  In another aspect of the second liquid crystal device of the present invention, the liquid crystal device is passively matrix driven in a normally black mode.

  According to this aspect, for example, by using a normally black mode passive matrix drive method using STN liquid crystal, high brightness and contrast ratio, and high-quality that has been accurately subjected to color correction in color display or monochrome display. Can be displayed.

  In another aspect of the second liquid crystal device of the present invention, the second polarizing plate is disposed between the first substrate and the light source, and is disposed between the first substrate and the other polarizing plate. And another phase difference plate.

  According to this aspect, if both polarizing plates are arranged such that the transmission axis of the polarizing plate on the second substrate side and the transmission axis of the polarizing plate on the first substrate side have a predetermined relationship, Due to the change in the alignment state of the liquid crystal due to application, light source light (transmitted light) emitted from the polarizing plate on the second substrate side can be modulated. Furthermore, color correction at the time of transmissive display can be performed relatively easily by using another retardation plate on the second substrate side.

  In another aspect of the second liquid crystal device of the present invention, irregularities are formed on the surface of the first substrate facing the second substrate.

  According to this aspect, since the external light reflected through the liquid crystal is reflected by the semi-transmissive reflective electrode layer formed in an uneven shape by being formed on the uneven surface of the substrate, the size and shape of the unevenness It is possible to obtain optimum reflection characteristics by controlling the above. Therefore, finally, brighter and higher quality display can be performed. In addition, as a formation method of such an unevenness | corrugation, the method of forming the surface of a 1st board | substrate in uneven | corrugated shape may be used, for example, and the method of forming an uneven | corrugated film | membrane on the surface on a flat 1st substrate may be sufficient. Furthermore, the transflective electrode layer itself can be formed in an uneven shape on the flat first substrate.

  In order to solve the above problems, an electronic apparatus according to the present invention includes the above-described first or second liquid crystal device according to the present invention (including the various aspects described above).

  According to the electronic device of the present invention, a reflective liquid crystal device capable of a bright and high-contrast reflective display without a double image due to parallax or display blur, and a bright and high-contrast reflective display and a transmissive display are provided. Various electronic devices such as a mobile phone, a wristwatch, an electronic notebook, and a notebook computer using a transflective liquid crystal device that can be switched and displayed can be realized.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

  Hereinafter, the best mode for carrying out the present invention will be described for each embodiment in order with reference to the drawings.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
First, the configuration of the reflective liquid crystal device according to the first embodiment of the present invention will be described with reference to FIGS. In the first embodiment, the present invention is applied to a reflective liquid crystal device of a passive matrix driving system. FIG. 1 is a schematic plan view showing the reflective liquid crystal device as viewed from the counter substrate side with the color filter formed on the counter substrate removed for convenience, and FIG. FIG. 3 is a schematic cross-sectional view of a reflective liquid crystal device showing a cross-section A ′ including a color filter, and FIG. 3 is a partial perspective view of the reflective liquid crystal device. Further, in FIG. 1, for convenience of explanation, six striped electrodes are schematically shown in the vertical and horizontal directions, but actually, there are a large number of electrodes, and in FIG. 2, each layer and each member are illustrated. In order to make the size recognizable above, the scale is different for each layer and each member. Further, FIG. 3 shows an enlarged view of the portion of the stripe-shaped electrode in three vertical and horizontal directions.

  1 to 3, the reflective liquid crystal device according to the first embodiment includes a first substrate 10, a transparent second substrate 20 disposed opposite to the first substrate 10, the first substrate 10 and the second substrate 10. A liquid crystal layer 50 sandwiched between the substrates 20, a plurality of stripe-shaped reflective electrodes 14 disposed on the side of the first substrate 10 facing the second substrate 20 (that is, the upper surface in FIG. 2), and the reflective electrodes And an alignment film 15 disposed on the substrate 14. The reflective liquid crystal device includes a color filter 23 disposed on a side of the second substrate facing the first substrate 10 (that is, a lower surface in FIG. 2), and a color filter flattened disposed on the color filter 23. A film 24, a plurality of striped transparent electrodes 21 disposed so as to cross the reflective electrode 14 on the color filter planarizing film 24, and an alignment film 25 disposed on the transparent electrode 21. Has been. The position of the color filter 23 may be formed between the reflective electrode 14 and the first substrate 10. In the color filter 23, RGB (red, blue, green) color portions are arranged in a predetermined order for each pixel corresponding to each planar region where the reflective electrode 14 and the transparent electrode 21 intersect each other (see FIG. 3). .

  The first substrate 10 and the second substrate 20 are bonded together around the liquid crystal layer 50 by a sealing material 31 (see FIGS. 1 and 2), and the liquid crystal layer 50 is sealed by the sealing material 31 and the sealing material 32. It is enclosed between the first substrate 10 and the second substrate 20. The reflective liquid crystal device further includes a polarizing plate 105, a first retardation plate 106 and a second retardation plate 116 on the opposite side of the second substrate 20 from the liquid crystal layer 50.

  Since the first substrate 10 is not required to be transparent, for example, a quartz substrate as well as a semiconductor substrate can be used, but the second substrate 20 should be transparent or at least translucent to visible light. For example, a glass substrate or a quartz substrate is used because it is required.

  The reflective electrode 14 is made of, for example, a reflective film containing Al as a main component, and is formed by vapor deposition or sputtering. On the other hand, the transparent electrode 21 is made of a transparent conductive thin film such as an ITO film.

  Each of the alignment films 15 and 25 is made of an organic thin film such as a polyimide thin film, is formed by spin coating or flexographic printing, and is subjected to a predetermined alignment process such as a rubbing process.

  The liquid crystal layer 50 takes a predetermined alignment state by the alignment films 15 and 25 in a state where an electric field is not applied between the reflective electrode 14 and the transparent electrode 21. The liquid crystal layer 50 is made of, for example, STN liquid crystal in which one kind or several kinds of nematic liquid crystals are mixed.

  The sealing material 31 is an adhesive made of, for example, a photocurable resin or a thermosetting resin. In particular, when the reflective liquid crystal device is small and has a diagonal size of about several inches or less, a gap material (spacer) such as glass fiber or glass beads for setting the distance between both substrates in the sealing material to a predetermined value. Is mixed. However, such a gap material may be mixed in the liquid crystal layer 50 when the reflective liquid crystal device has a large size of about several inches to 10 inches diagonal. The sealing material 32 is made of a resinous adhesive or the like that seals the injection port after liquid crystal is vacuum-injected through the injection port of the sealing material 31.

  The color filter 23 is a color material film that transmits blue (B) light, green (G) light, and red (R) light for each pixel, and takes a delta arrangement, a stripe arrangement, a mosaic arrangement, a triangle arrangement, or the like. . Further, a light shielding film called a black mask or a black matrix is formed at the boundary of each pixel, thereby preventing color mixing between the pixels.

  Although omitted in FIGS. 1 and 2, a frame is formed of the same or different material as the light shielding film in the color filter 23, for example, in parallel with the inside of the sealing material 52, and the periphery of the image display area is It is prescribed. Such a frame may be formed on one or both of the second substrate 20 side and the first substrate 10 side. Alternatively, such a frame may be defined by an edge of a light-shielding case in which the reflective liquid crystal device is inserted.

  Particularly in the first embodiment, the twist angle θt of the liquid crystal layer 50 made of STN liquid crystal is limited to 230 to 260 degrees, and Δnd of the liquid crystal (product of optical anisotropy Δn and layer thickness d) is The minimum value is 0.85 μm or less and the maximum value is 0.70 μm or more (however, it goes without saying that the minimum value is set smaller than the maximum value). Such a twist angle θt can be defined with high accuracy by the rubbing direction with respect to the alignment film 15 and the alignment film 25. Δnd of the first retardation plate 106 is 150 ± 50 nm or 600 ± 50 nm, and Δnd of the second retardation plate 116 is 550 ± 50 nm. The angle θ1 formed between the transmission axis or absorption axis of the polarizing plate 105 and the optical axis of the second retardation plate 116 is 15 to 35 degrees, and the optical axis of the first retardation plate 106 and the second retardation plate 116 are The angle θ2 made with the optical axis is 60 to 80 degrees. Therefore, according to the reflective liquid crystal device of the first embodiment, the reflectance with respect to light in the vicinity of a wavelength of 550 nm is high, and a bright and high-contrast reflective color display is possible. Further, by using two retardation plates, color correction can be performed relatively easily and accurately, and particularly beautiful black display and white display (that is, red, blue, green, etc.) Not black display or white display).

  Further, since the minimum value of Δnd of the liquid crystal is 0.85 μm or less and the maximum value is 0.70 μm or more, it can be applied to the applied voltage of the liquid crystal device in a relatively wide operating temperature range required by the device specifications. The transmittance can be changed monotonously (for example, monotonically increasing in the case of normally black mode, monotonically decreasing in the case of normally white mode), and color gradation can be displayed accurately. It becomes. However, as described above, Δnd of the liquid crystal has a minimum value of 0.85 μm or less and a maximum value of 0.70 μm or more. In this embodiment, in particular, the surface of the uppermost layers of both substrates that define the liquid crystal layer thickness Since the alignment film 15 or the surface of the reflective electrode 14 that is the base of the alignment film 15 is flat, Δnd of the liquid crystal may simply be 0.70 to 0.85 μm. On the other hand, when the uppermost layer surfaces of both substrates defining the liquid crystal layer thickness are uneven as in the embodiments described later (see the third and fourth embodiments), the Δnd of the liquid crystal is set to the entire area in each pixel. Since it may be difficult or impossible to be 0.70 to 0.85 μm, the minimum value of Δnd of the liquid crystal is 0.85 μm or less and the maximum value is 0. What is necessary is just to set so that it may be 70 micrometers or more.

  Next, the operation of the reflective liquid crystal device of the first embodiment configured as described above will be described with reference to FIG. The reflective liquid crystal device is driven by a normally black mode passive matrix driving method.

  In FIG. 2, external light incident from the side of the polarizing plate 105 (that is, the upper side in FIG. 2) is provided on the first substrate 10 via the polarizing plate 105, the transparent second substrate 20 and the liquid crystal layer 50. The light is reflected by the reflective electrode 14 and is emitted from the polarizing plate 105 side again through the liquid crystal layer 50, the second substrate 20 and the polarizing plate 105. Here, if an image signal and a scanning signal are supplied from the external circuit to the reflective electrode 14 and the transparent electrode 21 at a predetermined timing, the liquid crystal layer 50 at the intersection of the reflective electrode 14 and the transparent electrode 21 is provided for each row. Alternatively, the electric field is sequentially applied to each column or each pixel. Therefore, by controlling the alignment state of the liquid crystal layer 50 in units of pixels by this applied voltage, the amount of light transmitted through the polarizing plate 105 having a fixed transmission axis and absorption axis is modulated in units of pixels, and color gradation Display is possible.

  As described above, according to the present embodiment, compared with the traditional reflective liquid crystal device that reflects the reflection plate provided outside the first substrate, the presence of the transparent substrate between the liquid crystal layer and the reflection plate doubles. There is no occurrence of reflection or blurring of display, and sufficient color development can be obtained even when the color is changed. Moreover, according to the present embodiment, since the external light is reflected by the reflective electrode 14 on the upper side of the first substrate 10, the parallax in the display image is reduced and the brightness in the display image is improved as the optical path is shortened. In particular, the twist angle θt, the angle θ1 and the angle θ2 of the liquid crystal layer 50, Δnd of the liquid crystal, Δnd of the first phase plate 106, and Δnd of the second phase plate 116 are within the predetermined ranges described above. The normally black mode realizes bright and high-contrast color display.

  In the first embodiment described above, the terminal portion drawn out to the terminal region on the first substrate 10 of the reflective electrode 14 and the terminal portion drawn out to the terminal region on the second substrate 10 of the transparent electrode 21 include, for example, A driving LSI including a data line driving circuit and a scanning line driving circuit which are mounted on a TAB (Tape Automated Bonding) substrate and which supplies image signals and scanning signals to the reflective electrode 14 and the transparent electrode 21 at a predetermined timing is different. You may make it connect electrically and mechanically through an anisotropic conductive film. Alternatively, such a data line driving circuit or a scanning line driving circuit is formed in a peripheral region on the first substrate 10 or the second substrate 20 outside the sealing material 31, so that a so-called driving circuit built-in reflection type liquid crystal device is formed. Further, an inspection circuit for inspecting the quality, defects, etc. of the liquid crystal device during manufacture or at the time of shipment may be formed to form a so-called peripheral liquid crystal reflective liquid crystal device.

  In addition, in the first embodiment, in addition to the passive matrix driving method, a TFT (Thin Film Transistor) active matrix driving method, a TFD (Thin Film Diode) active matrix driving method, a segment driving method, and the like are known. Various driving methods can be adopted. On the second substrate 20, a plurality of stripe-shaped or segment-shaped transparent electrodes are appropriately formed according to the driving method, or transparent electrodes are formed on almost the entire surface of the second substrate 20. Or you may drive by the horizontal electric field parallel to a board | substrate between the adjacent reflective electrodes 14 on the 1st board | substrate 10 without providing a counter electrode on the 2nd board | substrate 20. FIG. Further, the normally white mode may be adopted without being limited to the normally black mode. Furthermore, a micro lens may be formed on the second substrate 20 so as to correspond to one pixel. In this way, a bright liquid crystal device can be realized by improving the collection efficiency of incident light. Furthermore, a plurality of interference layers having different refractive indexes may be deposited on the second substrate 20 to form a dichroic filter that produces RGB colors by utilizing light interference. According to this counter substrate with a dichroic filter, a brighter color liquid crystal device can be realized.

  Further, as shown in FIG. 2, in the first embodiment, the reflective electrode 14 is formed from a single layer mainly composed of Al, thereby improving the reflectance at a relatively easy manufacturing process and at a relatively low cost. Can be planned. However, even if the main component of the reflective electrode 14 is made of another metal such as Ag (silver) or Cr (chromium), the effects in the first embodiment as described above can be obtained.

  Here, specific examples based on the first embodiment will be described with reference to FIGS. 4 shows the twist angle θt of the liquid crystal layer 50, Δnd of the liquid crystal layer 50, retardation Δnd of the second retardation plate 116 in the first to sixth examples (referred to as R2 Δnd in the table of FIG. 4). Δn is the optical anisotropy of the retardation plate, d is the retardation plate thickness), retardation Δnd of the first retardation plate 106 (denoted as R1 Δnd in the table of FIG. 4), angle θ1 and angle θ2. It is a table | surface shown with the brightness (reflectance) and contrast ratio at the time of reflection type display.

  Specific examples 1 to 3 are examples of driving in normally black mode with 1/120 duty and 1/13 bias, and specific examples 4 to 6 are 1/240 duty and 1/13 bias. This is an example of driving in a normally black mode.

  For example, as shown in FIG. 5, according to the settings of the angles θ1, θ2, and θt in each specific example, from the incident side of the external light, the absorption axis direction A1 of the polarizing plate 105, the slow phase of the second retardation plate 116 If the axis direction A2, the slow axis direction A3 of the first retardation plate 106, the rubbing direction A4 of the alignment film 25, and the rubbing direction A5 of the alignment film 15 are set, high reflectivity (about 24% to 32%). And a high contrast ratio (about 11 to 19). In FIG. 5, the extending direction of the striped reflective electrode 14 is the x direction (lateral direction), and the extending direction of the striped transparent electrode 21 is the y direction (vertical direction).

  Further, as shown in FIG. 6, when the reflective liquid crystal device adopting such parameter setting is driven in the normally black mode with the above-mentioned 1/120 duty and 1/13 bias, for example, the liquid crystal applied voltage is about As the voltage increases from 2.0 V to about 2.2 V, a characteristic is obtained in which the reflectance increases smoothly and monotonously from about 0% to about 60% which is the maximum value.

  As is apparent from FIGS. 4 to 6, according to the first embodiment described above, the twist angle θt of the liquid crystal layer 50, Δnd of the liquid crystal layer 50, R2 Δnd of the second retardation plate 116, the first retardation plate 106 In each of the first to sixth specific examples in which R1 Δnd, the angle θ1 and the angle θ2 are set, a high reflectance exceeding 20% is obtained, so that a reflective display that is visually bright is obtained. At the same time, a high contrast display exceeding 10 can be obtained, and a high-quality gradation display can be achieved due to a favorable reflectance increase characteristic with respect to the liquid crystal applied voltage.

  In the various embodiments of the present invention including this embodiment, the first retardation plate 106 and the second retardation plate 116 are each preferably composed of a biaxial retardation plate, and the condition Nx> Nz> Ny (however, Nx: refractive index in the X-axis direction, Nz: refractive index in the Z-axis direction, Ny: refractive index in the Y-axis direction). If comprised in this way, a viewing angle can be expanded. However, even if the first retardation plate 106 and the second retardation plate 116 are formed of a uniaxial retardation plate, the benefits of the above-described embodiment can be obtained.

(Second embodiment)
Next, a reflective liquid crystal device according to a second embodiment of the invention will be described with reference to FIG. The second embodiment of the present invention is different from the first embodiment in the parameter settings relating to the first retardation plate 106, the second retardation plate 116, and the polarizing plate 105, and other configurations and operations are shown in FIGS. This is the same as the first embodiment shown.

  That is, in the second embodiment, the twist angle θt of the liquid crystal layer 50 made of STN liquid crystal is limited to 230 to 260 degrees as in the first embodiment, and Δnd of the liquid crystal layer 50 is also limited to the first embodiment. Similarly, the minimum value is 0.85 μm or less and the maximum value is 0.70 μm or more.

  In the second embodiment, unlike the first embodiment, Δnd of the first retardation plate 106 is 150 ± 50 nm, Δnd of the second retardation plate 116 is 610 ± 60 nm, and An angle θ1 formed between the transmission axis or the absorption axis and the optical axis of the second retardation plate 116 is 10 to 35 degrees, and the optical axis of the first retardation plate 106 and the optical axis of the second retardation plate 116 are set. The formed angle θ2 is 30 to 60 degrees. Therefore, according to the reflective liquid crystal device of the second embodiment, the reflectance with respect to light having a wavelength of about 550 nm is increased, and a bright and high-contrast reflective color display is possible. Further, by using two retardation plates, color correction can be performed relatively easily and accurately, and particularly beautiful black display and white display (that is, red, blue, green, etc.) Not black display or white display).

  In the second embodiment, as in the case of the first embodiment, Δnd of the liquid crystal has a minimum value of 0.85 μm or less and a maximum value of 0.70 μm or more. In a relatively wide operating temperature range, the change in transmittance with respect to the applied voltage of the liquid crystal device can be made monotonous, and color gradation display can be performed accurately.

  Here, each specific example based on 2nd Example is demonstrated with reference to FIG. 7 shows the twist angle θt of the liquid crystal layer 50, Δnd of the liquid crystal layer 50, Δnd of the second retardation plate 116 (referred to as R2 Δnd in the table of FIG. 3), and the first example. 4 is a table showing Δnd (denoted as R1 Δnd in the table of FIG. 3), angle θ1 and angle θ2 of the phase difference plate 106 together with brightness (reflectance) and contrast ratio in the reflective display. 7 to 12 are examples of driving in the normally black mode with 1/120 duty and 1/13 bias.

  As is apparent from FIG. 7, according to the second embodiment described above, the twist angle θt of the liquid crystal layer 50, Δnd of the liquid crystal layer 50, R2 Δnd of the second retardation plate 116, R1 Δnd of the first retardation plate 106 In each of the specific example 7 to the specific example 12 in which the angle θ1 and the angle θ2 are set, a high reflectance exceeding 30% is obtained. That is, a reflective display that is very bright visually can be obtained. At the same time, a high contrast display exceeding “10” is obtained.

(Third embodiment)
Next, a reflective liquid crystal device according to a third embodiment of the invention is described with reference to FIG. In the third embodiment shown in FIG. 8, the same components as those in the first embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof is omitted.

  In the third embodiment, as compared with the first or second embodiment, the surface of the first substrate 10 is uneven, and accordingly, the reflective electrode 14 and the alignment film 15 are also formed uneven. Furthermore, the layer thickness d of the liquid crystal layer 50 differs slightly depending on the position in each pixel, and the other configurations are the same as those in the first or second embodiment.

  As described above, in the third embodiment, by using the first substrate 10 ′ with the unevenness formed on the surface, the surface facing the liquid crystal layer 50 of the reflective electrode 14 is made uneven so as to eliminate the specular feeling, and the scattering surface (white surface) ) In addition, the viewing angle can be widened by scattering due to unevenness. This uneven shape can be formed relatively easily by roughening the substrate itself with hydrofluoric acid. In the third embodiment, as in the first or second embodiment, Δnd of the liquid crystal layer 50 has a minimum value (value at the convex portion) of 0.85 μm or less and a maximum value (value at the concave portion) of 0. .70 μm or more. Note that a transparent flattening film is formed on the uneven surface of the reflective electrode 14 and the surface facing the liquid crystal layer 50 (the surface on which the alignment film 15 is formed) is flattened from the viewpoint of preventing liquid crystal alignment defects. Desirable from.

(Fourth embodiment)
Next, a reflective liquid crystal device according to a fourth embodiment of the present invention is described with reference to FIG. In the fourth embodiment shown in FIG. 9, the same components as those in the first embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof is omitted.

  In the fourth embodiment, as compared with the first or second embodiment, the uneven film 10u is formed on the surface of the first substrate 10, and accordingly, the reflective electrode 14 and the alignment film 15 are also formed uneven. Furthermore, the layer thickness d of the liquid crystal layer 50 is slightly different depending on the position in each pixel, and the other configurations are the same as in the first or second embodiment.

  As described above, in the fourth embodiment, by forming the concavo-convex film 10 u on the first substrate 10, the surface facing the liquid crystal layer 50 of the reflective electrode 14 is made concavo-convex as in the case of the third embodiment. Is shown on the scattering surface (white surface). In addition, the viewing angle can be widened by scattering due to unevenness. Such an uneven film 10u can be formed relatively easily by laminating a photosensitive acrylic resin or the like on the base of the reflective electrode.

(5th Example)
Next, a reflective liquid crystal device according to a fifth embodiment of the invention is described with reference to FIGS. FIG. 10 is a cross-sectional view showing the laminated structure of the reflective electrode 14 ′ in the fifth embodiment, FIG. 11 is a plan view thereof, and FIG. 12 is a perspective view thereof. In the fifth embodiment shown in FIGS. 10 to 12, the same components as those in the first embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIGS. 10 to 12, in the fifth embodiment, instead of the reflective electrode 14 formed of a single layer in the first to fourth embodiments, the reflective electrode 14 ′ includes a stripe-shaped reflective film 141, It has a laminated structure including a transparent insulating film 142 disposed on the reflective film 141 and a striped transparent electrode 143 disposed on the insulating film 142, and the other configurations are from the first to the first. Similar to any of the four examples. If comprised in this way, by controlling the orientation state of the liquid crystal layer 50 using the transparent electrode 143 which consists of an ITO film etc. which were laminated | stacked on the 1st board | substrate 10, after reflection by the reflective film 141 which consists of Al films etc. The intensity of external light emitted as display light through the liquid crystal layer 50 can be controlled. In this case, the insulating film 142 may be formed using, for example, silicon oxide as a main component.

(Sixth embodiment)
Next, a transflective liquid crystal device according to a sixth embodiment of the present invention will be described with reference to FIGS. In the sixth embodiment, the present invention is applied to a transflective liquid crystal device. FIG. 13 is a schematic cross-sectional view showing the configuration of the second embodiment. Components similar to those of the first embodiment shown in FIG. Omitted.

  13 and 14, the transflective liquid crystal device of the sixth embodiment includes a transflective electrode 214 instead of the reflective electrode 14 of the first embodiment, and in addition to the configuration of the first embodiment. A polarizing plate 107 and a retardation plate 108 are provided on the opposite side of the first substrate 10 from the liquid crystal layer 50. Further, outside the polarizing plate 107, a fluorescent tube 119 and a light guide plate 118 for guiding the light from the fluorescent tube 119 from the polarizing plate 107 into the liquid crystal panel are provided. Other configurations are the same as those in the first embodiment.

  The transflective electrode 214 is made of a metal such as Ag or Al, and has a slit, an opening, and the like. For this reason, the transflective electrode 214 reflects light incident from the second substrate 20 side and transmits light source light from the first substrate 10 side.

  Here, various specific examples of slits and openings of the transflective electrode 214 will be described with reference to FIG.

  As shown in FIG. 15 (a), four rectangular slots may be arranged in every direction for each pixel, or as shown in FIG. 15 (b), five rectangular slots may be arranged side by side for each pixel. Alternatively, a large number of circular openings (for example, openings having a diameter of 2 μm) may be discretely arranged for each pixel as shown in FIG. 15 (c), or one relatively large number may be provided for each pixel as shown in FIG. 15 (d). Large rectangular slots may be placed. Such an opening can be easily produced by a photo process / development process / peeling process using a resist. The planar shape of the opening may be a square, a polygon, an ellipse, an irregular shape, or a slit extending across a plurality of pixels. Further, it is possible to open the opening at the same time when the reflective layer is formed, and in this way, it is not necessary to increase the number of manufacturing steps. In particular, in the case of a slit as shown in FIGS. 15A, 15B, or 15D, the width of the slit is preferably about 3 to 20 μm. With this configuration, a bright and high-contrast display is possible during both the reflective display and the transmissive display. In addition to providing such slits and openings, for example, single-layer semi-transmissive reflections separated from each other when viewed in a plan view from a direction perpendicular to the second substrate 20 so that light can pass through the gap. The electrode 214 may be used.

  Returning to FIG. In FIG. 13, a light guide plate 118 that constitutes a backlight together with a fluorescent tube 119 is a transparent body such as an acrylic resin plate on which a rough surface for scattering is formed on the entire back surface or a printed layer for scattering is formed. The light from the fluorescent tube 119, which is a light source, is received at the end face, and substantially uniform light is emitted from the upper surface of the drawing.

  As light sources that are turned on during transmissive display, LED (Light Emitting Diode) elements and EL (Electro-Luminescence) elements are suitable for small liquid crystal devices, and for large liquid crystal devices. A fluorescent tube 119 or the like for introducing light from the side through a light guide plate is suitable. A reflective polarizer may be further disposed between the first substrate 10 and the light guide plate 118 for the purpose of effectively using light.

  Thus, in the sixth embodiment, the polarizing plate 105, the first retardation plate 106, and the second retardation plate 116 are disposed on the upper side of the liquid crystal cell, and the polarizing plate 107 and the retardation plate are disposed on the lower side of the liquid crystal cell. Since 108 is arranged, good display control can be performed in both the reflective display and the transmissive display. More specifically, the first retardation plate 106 and the second retardation plate 116 reduce the influence on the color tone such as coloring due to the wavelength dispersion of light during the reflective display (that is, the first rank). The phase difference plate 106 and the second phase difference plate 116 are used to optimize the display at the time of reflection type display, and the phase difference plate 108 is used to adjust the color tone such as coloring due to the wavelength dispersion of light at the time of transmission type display. (That is, under the condition that the display is optimized at the time of reflection type display by the first phase difference plate 106 and the second phase difference plate 116, and further, the transmission type by the phase difference plate 108). The display is optimized at the time of display). In addition, about each phase difference plate, it is also possible to arrange | position several sheets or three or more phase difference plates by the coloring compensation of a liquid crystal cell, or viewing angle compensation. In this way, if a plurality of retardation plates are used, the color compensation or the visual compensation can be optimized more easily.

  Furthermore, the optical characteristics of the polarizing plate 105, the first retardation plate 106, the second retardation plate 116, the liquid crystal layer 50, and the transflective electrode 214 are set so as to increase the contrast at the time of reflective display. Thus, by setting the optical characteristics of the polarizing plate 107 and the retardation plate 108 so as to increase the contrast during transmissive display, high contrast characteristics can be obtained in both the reflective display and the transmissive display. For example, during reflective display, external light passes through the polarizing plate 105 and becomes linearly polarized light, and further passes through the phase difference plate 106 and the liquid crystal layer 50 in a voltage non-applied state (dark display state) to become right circularly polarized light. The transflective electrode 214 reaches the transflective electrode 214, is reflected here and reverses its traveling direction and is converted to left circularly polarized light, and is again converted to linearly polarized light through the liquid crystal layer 50 in the non-voltage applied state. The optical characteristics of the polarizing plate 105, the first retardation plate 106, the second retardation plate 116, the liquid crystal layer 50, and the transflective electrode 214 are set so as to be absorbed (that is, darken). At this time, the external light passing through the liquid crystal layer 50 portion in the voltage application state (bright display state) passes through the liquid crystal layer 50 portion, and is reflected by the transflective electrode 214 and emitted from the polarizing plate 105 (that is, Brighten). On the other hand, during transmissive display, the light source light emitted from the backlight and transmitted through the semi-transmissive reflective electrode 214 via the polarizing plate 107 and the phase difference plate 108 is reflected by the semi-transmissive reflective electrode 214 during the reflective display described above. The optical characteristics of the polarizing plate 107 and the phase difference plate 108 are set so that the light is similar to the left circularly polarized light. Then, although the light source and the optical path are different from those in the reflective display, the light source light transmitted through the transflective electrode 214 in the transmissive display is reflected by the transflective electrode 214 in the reflective display. Like the light, it passes through the liquid crystal layer 50 in a voltage non-applied state (dark display state) and is converted into linearly polarized light and absorbed by the polarizing plate 105 (that is, darkened). At this time, light passing through the liquid crystal layer 50 portion in the voltage application state (bright display state) passes through the liquid crystal layer 50 portion and exits from the polarizing plate 105 (that is, becomes brighter).

  As described above, the liquid crystal device according to this embodiment includes the polarizing plate 105, the first retardation plate 106, the second retardation plate 116, the polarizing plate 107, and the retardation plate 108. Good color compensation and high contrast characteristics can be obtained in any of the displays. Note that these optical characteristics can be set according to the brightness and contrast ratio required in the specifications of the liquid crystal device, experimentally, theoretically, or by simulation.

  In the sixth embodiment, in particular, the twist angle θt of the liquid crystal layer 50 made of STN liquid crystal is limited to 230 to 260 degrees, and Δnd of the liquid crystal has a minimum value of 0.85 μm or less and a maximum value thereof. It is 0.70 μm or more. Such a twist angle θt can be defined with high accuracy by the rubbing direction with respect to the alignment film 15 and the alignment film 25. Δnd of the first retardation plate 106 is 150 ± 50 nm or 600 ± 50 nm, and Δnd of the second retardation plate 116 is 550 ± 50 nm. The angle θ1 formed between the transmission axis or absorption axis of the polarizing plate 105 and the optical axis of the second retardation plate 116 is 15 to 35 degrees, and the optical axis of the first retardation plate 106 and the second retardation plate 116 are The angle θ2 made with the optical axis is 60 to 80 degrees. Therefore, according to the reflective liquid crystal device of the sixth embodiment, the reflectance with respect to light having a wavelength near 550 nm is increased, and a bright and high-contrast reflective color display is possible. Further, by using two retardation plates, color correction can be performed relatively easily and accurately, and particularly beautiful black display and white display (that is, red, blue, green, etc.) Not black display or white display).

  Further, since the minimum value of Δnd of the liquid crystal is 0.85 μm or less and the maximum value is 0.70 μm or more, it can be applied to the applied voltage of the liquid crystal device in a relatively wide operating temperature range required by the device specifications. The change in transmittance can be made monotonous, and color gradation display can be performed accurately. However, as described above, Δnd of the liquid crystal has a minimum value of 0.85 μm or less and a maximum value of 0.70 μm or more. In this embodiment, in particular, the surface of the uppermost layers of both substrates that define the liquid crystal layer thickness However, since it is flat, Δnd of the liquid crystal may be simply 0.70 to 0.85 μm. On the other hand, when the uppermost layer surfaces of both substrates defining the liquid crystal layer thickness are uneven as in the examples described later (see the eighth and ninth examples), the Δnd of the liquid crystal is 0 over the entire pixel. .70 to 0.85 μm can be difficult or impossible, and in such a case, the Δnd of the liquid crystal has a minimum value of 0.85 μm or less and a maximum value of 0.70 μm or more as described above. What is necessary is just to set.

  Next, the operation of the transflective liquid crystal device of the sixth embodiment configured as described above will be described with reference to FIG. The transflective liquid crystal device of the sixth embodiment is driven by a normally black mode passive matrix driving method.

  First, the reflective display will be described. In this case, as in the case of the first embodiment, in FIG. 13, the external light incident from the side of the polarizing plate 105 (that is, the upper side in FIG. 13) is applied to the polarizing plate 105, the transparent second substrate 20, and the liquid crystal. The light is reflected by the transflective electrode 214 provided on the first substrate 10 through the layer 50, and is emitted from the polarizing plate 105 side again through the liquid crystal layer 50, the second substrate 20, and the polarizing plate 105. Here, if an image signal and a scanning signal are supplied to the transflective electrode 214 and the transparent electrode 21 from an external circuit at a predetermined timing, the liquid crystal layer 50 portion where the transflective electrode 214 and the transparent electrode 21 intersect with each other is supplied. In this case, an electric field is sequentially applied to every row, every column, or every pixel. Therefore, by controlling the alignment state of the liquid crystal layer 50 for each pixel by this applied voltage, the amount of light transmitted through the polarizing plate 105 is modulated, and color gradation display is possible.

  As described above, according to the present embodiment, in the reflective display, the liquid crystal layer and the reflective plate are separated from each other as compared with the traditional reflective liquid crystal device that reflects the reflective plate provided outside the first substrate. Due to the presence of the transparent substrate, there is no occurrence of double reflection or display bleeding, and sufficient color development can be obtained even when the color is changed. In addition, according to the present embodiment, since the external light is reflected by the transflective electrode 214 on the upper side of the first substrate 10, the parallax in the display image is reduced and the brightness in the display image is improved by the shortening of the optical path. In particular, the twist angle θt, the angle θ1 and the angle θ2 of the liquid crystal layer 50, Δnd of the liquid crystal layer 50, Δnd of the first retardation plate 106, and Δnd of the second retardation plate 116 are within the predetermined ranges described above. Therefore, bright and high contrast color display is realized by the normally black mode.

  Next, transmissive display will be described. In this case, in FIG. 13, the light source light incident from the lower side of the first substrate 10 through the polarizing plate 107 is transmitted through the opening of the semi-transmissive reflective electrode 214, and the liquid crystal layer 50, the second substrate 20, and the polarized light. The light is emitted from the polarizing plate 105 side through the plate 105. Here, if an image signal and a scanning signal are supplied from an external circuit to the transflective electrode 214 and the transparent electrode 21 at a predetermined timing, the liquid crystal layer 50 portion at the portion where the transflective electrode 214 and the transparent electrode 21 intersect is provided. The electric field is sequentially applied to each row, column, or pixel. Thus, by controlling the alignment state of the liquid crystal layer 50 in units of pixels, the light source light is modulated and gradation display becomes possible.

  In the sixth embodiment described above, as in the case of the first embodiment, the terminal portion of the transflective electrode 214 drawn to the terminal area on the first substrate 10 and the transparent electrode 21 on the second substrate 10 are used. The terminal portion led out to the terminal area is mounted on, for example, a TAB substrate, and a driving LSI including a data line driving circuit and a scanning line driving circuit is electrically and mechanically interposed through an anisotropic conductive film. You may make it connect to. Alternatively, it may be configured as a transflective liquid crystal device with a built-in drive circuit, and further, a so-called transflective liquid crystal device with a built-in peripheral circuit may be formed by forming an inspection circuit or the like. Further, the first retardation plate 106 and the second retardation plate 116 may be formed of a biaxial retardation plate or a uniaxial retardation plate.

  In addition, in the sixth embodiment, as in the first embodiment, in addition to the passive matrix driving method, various known driving methods such as a TFT active matrix driving method, a TFD active matrix driving method, and a segment driving method are used. It can be adopted. In addition, a plurality of stripe-shaped or segment-shaped transparent electrodes are appropriately formed on the second substrate 20 according to the driving method, or transparent electrodes are formed on almost the entire surface of the second substrate 20. Alternatively, it may be driven by a lateral electric field parallel to the substrate between adjacent semi-transmissive reflective electrodes 214 on the first substrate 10 without providing a counter electrode on the second substrate 20. Further, the normally white mode may be adopted without being limited to the normally black mode. Since the voltage-reflectivity (transmittance) characteristics of the liquid crystal cell are often different between the reflective display and the transmissive display, the drive voltage is different between the reflective display and the transmissive display, and each is optimized. Is preferable. Further, a microlens may be formed on the second substrate 20 so as to correspond to one pixel. Furthermore, a plurality of interference layers having different refractive indexes may be deposited on the second substrate 20 to form a dichroic filter that produces RGB colors by utilizing light interference.

  Further, as shown in FIG. 13, in the sixth embodiment, the transflective electrode 214 is formed from a single layer mainly composed of Al, so that the reflectivity can be reduced at a relatively easy manufacturing process and at a relatively low cost. Improvements can be made. However, even if the main component of the transflective electrode 214 is made of another metal such as Ag or Cr, the effect in the sixth embodiment as described above can be obtained.

(Seventh embodiment)
Next, a transflective liquid crystal device according to a seventh embodiment of the present invention is described. The seventh embodiment of the present invention differs from the sixth embodiment in the parameter settings relating to the first retardation plate 106, the second retardation plate 116, and the polarizing plate 105, and other configurations and operations are shown in FIGS. This is the same as the sixth embodiment shown.

  That is, in the seventh embodiment, the twist angle θt of the liquid crystal layer 50 made of STN liquid crystal is limited to 230 to 260 degrees as in the sixth embodiment, and Δnd of the liquid crystal layer 50 is also in the sixth embodiment. Similarly, the minimum value is 0.85 μm or less and the maximum value is 0.70 μm or more.

  In the seventh embodiment, unlike the sixth embodiment, Δnd of the first retardation plate 106 is 150 ± 50 nm, Δnd of the second retardation plate 116 is 610 ± 60 nm, and An angle θ1 formed between the transmission axis or the absorption axis and the optical axis of the second retardation plate 116 is 10 to 35 degrees, and the optical axis of the first retardation plate 106 and the optical axis of the second retardation plate 116 are set. The formed angle θ2 is 30 to 60 degrees. Therefore, according to the transflective liquid crystal device of the seventh embodiment, the reflectance with respect to light having a wavelength of about 550 nm is high, and a bright and high-contrast reflective color display is possible. Further, by using two retardation plates, color correction can be performed relatively easily and accurately, and particularly beautiful black display and white display (that is, red, blue, green, etc.) Not black display or white display).

  Further, as in the case of the sixth embodiment, the Δnd of the liquid crystal has a minimum value of 0.85 μm or less and a maximum value of 0.70 μm or more. The change in transmittance with respect to the voltage applied to the liquid crystal device in the temperature range can be made monotonous, and color gradation display can be performed accurately.

(Eighth embodiment)
Next, a transflective liquid crystal device according to an eighth embodiment of the present invention will be described with reference to FIG. In the eighth embodiment shown in FIG. 16, the same components as those in the sixth embodiment shown in FIGS. 13 to 15 are denoted by the same reference numerals, and the description thereof is omitted.

  In the eighth embodiment, as compared with the sixth or seventh embodiment, unevenness is formed on the surface of the first substrate 10, and accordingly, the transflective electrode 214 and the alignment film 15 are also formed uneven. Furthermore, the layer thickness d of the liquid crystal layer 50 differs slightly depending on the position in each pixel, and the other configurations are the same as in the sixth or seventh embodiment.

  As described above, in the eighth embodiment, by using the first substrate 10 ′ having the unevenness on the surface, the surface facing the liquid crystal layer 50 of the semi-transmissive reflective electrode 214 is made uneven so that the mirror surface is lost, and the scattering surface ( Show on white surface). In addition, the viewing angle can be widened by scattering due to unevenness.

(Ninth embodiment)
Next, a transflective liquid crystal device according to a ninth embodiment of the present invention will be described with reference to FIG. In the ninth embodiment shown in FIG. 17, the same components as those in the sixth embodiment shown in FIGS. 13 to 15 are denoted by the same reference numerals, and the description thereof is omitted.

  In the ninth embodiment, as compared with the sixth or seventh embodiment, the uneven film 10u is formed on the surface of the first substrate 10, and accordingly, the transflective electrode 214 and the alignment film 15 are also formed uneven. In addition, the layer thickness d of the liquid crystal layer 50 is slightly different depending on the position in each pixel, and the other configurations are the same as those in the sixth or seventh embodiment.

  As described above, in the ninth embodiment, by forming the uneven film 10u on the first substrate 10, the surface of the transflective electrode 214 facing the liquid crystal layer 50 is made uneven as in the case of the eighth embodiment. Eliminates specular feeling and shows it on the scattering surface (white surface). In addition, the viewing angle can be widened by scattering due to unevenness.

(Tenth embodiment)
Next, a transflective liquid crystal device according to a tenth embodiment of the present invention will be described with reference to FIGS. FIG. 18 is a cross-sectional view showing the laminated structure of the transflective electrode 214 ′ in the tenth embodiment, FIG. 19 is a plan view thereof, and FIG. 20 is a perspective view thereof. In the tenth embodiment shown in FIGS. 18 to 20, the same components as those in the sixth embodiment shown in FIGS. 13 to 15 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIGS. 18 to 20, in the tenth embodiment, instead of the semi-transmissive reflective electrode 214 formed of a single layer in the sixth to ninth embodiments, the semi-transmissive reflective electrode 214 ′ has a stripe-shaped semi-transmissive structure. It has a laminated structure including a reflective film 241, a transparent insulating film 242 disposed on the transflective film 241, and a striped transparent electrode 243 disposed on the insulating film 242. A slit 241h is opened in the semi-transmissive reflective film 241, and a recess 243h is formed in the transparent electrode 243 correspondingly. Other configurations are the same as those in any of the sixth to ninth embodiments.

  According to this configuration, at the time of reflective display, the alignment state of the liquid crystal layer 50 is controlled using the transparent electrode 243 made of an ITO film or the like laminated on the first substrate 10, so that the transflective film made of an Al film or the like is used. The intensity of external light emitted as display light through the liquid crystal layer 50 after reflection by the reflective film 241 can be controlled. At the time of transmissive display, the transparent electrode 243 made of an ITO film or the like laminated on the first substrate 10 is used to control the alignment state of the liquid crystal layer 50, so that it is transmitted through the transflective film 241 made of an Al film or the like. The light source light intensity emitted as display light through the liquid crystal layer 50 can be controlled. In this case, the insulating film 242 may be formed using, for example, silicon oxide as a main component.

(Eleventh embodiment)
Next, a reflective liquid crystal device according to an eleventh embodiment of the present invention will be described with reference to FIGS. FIG. 21 is a schematic plan view of the eleventh embodiment, FIG. 22 is a sectional view taken along the line AA ′, and FIG. 23 is a reflective electrode incorporating the color filter in the eleventh embodiment. It is a partial perspective view which shows the structure of a layer. In the eleventh embodiment shown in FIGS. 21 to 23, the same components as those in the first embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIGS. 21 to 23, in the eleventh embodiment, compared to the first embodiment, the second substrate 20 is provided with striped transparent electrodes 321 extending in the horizontal direction in FIG. On the one substrate 10 side, a striped transparent electrode 314a extending in the vertical direction in FIG. 21, a color filter 323, a planarizing film 324 of the color filter 323, and a solid reflecting plate 314b constituting a reflecting electrode layer together with the transparent electrode 314a. (In particular, the color filter 323 is formed in the reflective electrode layer), and the other configuration is the same as that of the first embodiment.

  Even in the configuration of the eleventh embodiment, as in the case of the first embodiment, the presence of the transparent substrate between the liquid crystal layer and the reflector does not cause double reflection or display blurring. Even when it is colored, it is possible to obtain a sufficient color. Moreover, since the external light is reflected by the reflecting plate 314b on the upper side of the first substrate 10, the parallax in the display image is reduced and the brightness in the display image is improved. In particular, the twist angle θt, the angle θ1 and the angle θ2 of the liquid crystal layer 50, Δnd of the liquid crystal, Δnd of the first retardation plate 106, and Δnd of the second retardation plate 116 are within the predetermined ranges described above. The normally black mode realizes bright and high-contrast color display.

  Even in the second to tenth embodiments described above, the twist angle θt, the angle θ1, and the angle of the liquid crystal layer 50 can be used even when the color filter is formed on the first substrate 10 as in the eleventh embodiment. A similar effect can be obtained if θ2, Δnd of the liquid crystal, Δnd of the first retardation plate 106, and Δnd of the second retardation plate 116 are within the predetermined ranges described above.

(Twelfth embodiment)
Next, a twelfth embodiment of the present invention will be described with reference to FIG. The twelfth embodiment comprises various electronic devices to which the reflection type or transflective liquid crystal device of the first to eleventh embodiments of the present invention described above is applied.

  First, if the liquid crystal device according to the first to eleventh embodiments is applied to a display unit 1001 of a mobile phone 1000 as shown in FIG. 24A, for example, it is bright and has high contrast, and has almost no parallax and high definition. An energy-saving mobile phone that performs color display can be realized.

  Further, when applied to the display unit 1101 of the wristwatch 1100 as shown in FIG. 24B, it is possible to realize an energy-saving wristwatch that is bright and has high contrast and that has almost no parallax and performs high-definition color display.

  Further, in a personal computer (or information terminal) 1200 as shown in FIG. 24C, when applied to a display screen 1206 provided in a cover that can be freely opened and closed on a main body 1204 with a keyboard 1202, it is bright and has high contrast. In addition, it is possible to realize an energy-saving personal computer that performs high-definition color display with almost no parallax.

  In addition to the electronic devices shown in FIG. 24, a liquid crystal television, a viewfinder type or a monitor direct-view type video tape recorder, a car navigation device, an electronic notebook, a calculator, a word processor, an engineering work station (EWS), a video phone, The reflective or transflective liquid crystal devices of the first to eleventh embodiments can also be applied to electronic devices such as POS terminals and devices equipped with a touch panel.

  The present invention is not limited to the embodiments described above, and can be implemented by appropriately changing the embodiments without departing from the scope of the present invention.

  The reflective liquid crystal device according to the present invention can be used as various display devices with low power consumption that are suitable for color display because both the brightness and the contrast ratio are enhanced, and the transflective liquid crystal device according to the present invention. Can be used as various display devices suitable for color display because both brightness and contrast ratio are enhanced particularly in reflective display, and as a liquid crystal device constituting the display unit of various electronic devices. Is available. In addition, an electronic apparatus according to the present invention includes a liquid crystal television configured using such a liquid crystal device, a viewfinder type or monitor direct-view type video tape recorder, a car navigation device, an electronic notebook, a calculator, a word processor, a workstation, It can be used as a mobile phone, a video phone, a POS terminal, a touch panel, or the like.

1 shows a passive matrix drive type reflective liquid crystal device according to a first embodiment in the best mode for carrying out the present invention as viewed from the counter substrate side with the color filter formed on the counter substrate removed for convenience. It is a schematic plan view. FIG. 2 is a schematic cross-sectional view of a reflective liquid crystal device showing a cross-section A-A ′ of FIG. 1 including a color filter. It is a partial perspective view of the reflective liquid crystal device of the first embodiment. It is a table | surface which shows the parameter setting, the brightness, and contrast ratio in the specific example 1-specific example 6 based on 1st Example. It is explanatory drawing which shows typically an example of the relationship of the various angles parameter-set by 1st Example on the board | substrate surface. FIG. 6 is a characteristic diagram showing reflectance characteristics with respect to a liquid crystal applied voltage when driving in a normally black mode according to the first embodiment. It is a table | surface which shows the parameter setting, the brightness, and contrast ratio in the specific examples 7-12 based on 2nd Example. It is sectional drawing of the reflection type liquid crystal device of the passive matrix drive system which is 3rd Example in the best form for implementing this invention. It is sectional drawing of the reflection type liquid crystal device of the passive matrix drive system which is the 4th Example in the best form for implementing this invention. It is sectional drawing in the reflection electrode vicinity of the reflection type liquid crystal device of 5th Example in the best form for implementing this invention. It is a top view of the reflective electrode of 5th Example shown in FIG. It is a perspective view of the reflective electrode of 5th Example shown in FIG. It is sectional drawing of the transflective liquid crystal device of the passive matrix drive system which is the 6th Example in the best form for implementing this invention. It is a partial perspective view of the transflective liquid crystal device of the sixth embodiment. It is an enlarged plan view which shows the various specific examples which concern on the slit provided in the transflective layer of 6th Example, and an opening part. It is sectional drawing of the transflective liquid crystal device of the passive matrix drive system which is the 8th Example in the best form for implementing this invention. It is sectional drawing of the transflective liquid crystal device of the passive matrix drive system which is the 9th Example in the best form for implementing this invention. It is sectional drawing in the transflective electrode vicinity of the transflective liquid crystal device of 10th Example in the best form for implementing this invention. It is a top view of the transflective electrode of 10th Example shown in FIG. FIG. 19 is a perspective view of the transflective electrode of the tenth embodiment shown in FIG. 18. FIG. 21 is a schematic plan view of a passive-matrix driven reflective liquid crystal device that is an eleventh embodiment according to the best mode for carrying out the present invention. It is A-A 'sectional drawing of FIG. It is a partial perspective view which shows the structure of the reflective electrode and color filter in the reflection type liquid crystal device of 11th Example. It is an external view of the various electronic devices which are the 12th Example in the best form for implementing this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... 1st board | substrate 14 ... Reflective electrode 15 ... Orientation film 20 ... 2nd board | substrate 21 ... Transparent electrode 23 ... Color filter 25 ... Orientation film 31 ... Sealing material 32 ... Sealing material 105 ... Polarizing plate 106 ... 1st phase difference plate 116: Second retardation plate 214: Transflective electrode

Claims (5)

A first substrate;
A transparent second substrate disposed opposite the first substrate;
Liquid crystal sandwiched between the first and second substrates;
A reflective electrode layer disposed on a side of the first substrate facing the second substrate;
A polarizing plate provided on the opposite side of the second substrate from the first substrate;
A first retardation plate disposed between the polarizing plate and the second substrate;
A second retardation plate disposed between the polarizing plate and the first retardation plate;
With a plurality of pixels ,
The surface of the reflective electrode layer has irregularities,
The layer thickness of the liquid crystal layer is not constant within the pixel,
The twist angle of the liquid crystal is 230 to 260 degrees,
Δnd of the liquid crystal (product of optical anisotropy Δn and layer thickness d) has a minimum value of 0.85 μm or less and a maximum value of 0.70 μm or more,
Δnd of the first retardation plate is 150 ± 50 nm,
Δnd of the second retardation plate is 610 ± 60 nm,
An angle θ1 formed by the transmission axis or absorption axis of the polarizing plate and the optical axis of the second retardation plate is 10 to 35 degrees,
An angle θ2 formed by the optical axis of the first retardation plate and the optical axis of the second retardation plate is 30 to 60 degrees. A first substrate;
A transparent second substrate disposed opposite the first substrate;
Liquid crystal sandwiched between the first and second substrates;
A transflective electrode layer disposed on a side of the first substrate facing the second substrate;
A polarizing plate provided on the opposite side of the second substrate from the first substrate;
A first retardation plate disposed between the polarizing plate and the second substrate;
A second retardation plate disposed between the polarizing plate and the first retardation plate;
With a plurality of pixels ,
The surface of the reflective electrode layer has irregularities,
The layer thickness of the liquid crystal layer is not constant within the pixel,
The twist angle of the liquid crystal is 230 to 260 degrees,
Δnd of the liquid crystal (product of optical anisotropy Δn and layer thickness d) has a minimum value of 0.85 μm or less and a maximum value of 0.70 μm or more,
Δnd of the first retardation plate is 150 ± 50 nm,
Δnd of the second retardation plate is 610 ± 60 nm,
An angle θ1 formed by the transmission axis or absorption axis of the polarizing plate and the optical axis of the second retardation plate is 10 to 35 degrees,
An angle θ2 formed by the optical axis of the first retardation plate and the optical axis of the second retardation plate is 30 to 60 degrees.   3. The liquid crystal device according to claim 1, wherein unevenness is formed on a surface of the first substrate facing the second substrate. 4.   The liquid crystal device according to claim 1, further comprising a color filter on a liquid crystal side surface of the first substrate or the second substrate.   An electronic apparatus comprising the liquid crystal device according to any one of claims 1 to 4.

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