JP4127317B2 - Liquid crystal display device and electronic device - Google Patents

Description

  The present invention relates to a liquid crystal display device and an electronic apparatus, and in particular, in a transflective liquid crystal display device having both a reflective type and a transmissive type, occurrence of disclination near the boundary between the reflective display and the transmissive display. The present invention relates to a technology that suppresses the image and makes it possible to obtain a bright and high-contrast display.

  The transflective liquid crystal display device that combines the reflective and transmissive display modes can be switched to either the reflective mode or the transmissive mode depending on the ambient brightness, reducing the power consumption. A clear display can be performed even when the is dark.

  Such a transflective liquid crystal display device has a configuration in which a liquid crystal layer is sandwiched between a translucent upper substrate and a lower substrate, and a light transmission slit is formed in a metal film such as aluminum, for example. A liquid crystal display device has been proposed in which the formed reflective film is provided on the inner surface of the lower substrate, and this reflective film functions as a semi-transmissive reflective film. In this case, in the reflection mode, external light incident from the upper substrate side passes through the liquid crystal layer, is reflected by the reflection film disposed on the inner surface of the lower substrate, passes through the liquid crystal layer again, and is displayed from the upper substrate side. Is done. On the other hand, in the transmissive mode, light from the backlight incident from the lower substrate side can be displayed outside from the upper substrate side after passing through the liquid crystal layer through the slit formed in the reflective film. Therefore, a region where the slit of the reflective film is formed is a transmissive display region, and a region where the slit of the reflective film is not formed is a reflective display region.

In the transflective liquid crystal display device having the above-described configuration, for example, when the thickness of the liquid crystal layer is d ₁ , the refractive index anisotropy of the liquid crystal is Δn, and the retardation of the liquid crystal expressed as an integrated value thereof is Δnd ₁ , the reflective display The retardation Δnd ₁ of the liquid crystal in the portion for performing the transmission is indicated by 2 × Δnd ₁ since the incident light reaches the observer after passing through the liquid crystal layer twice, but the retardation Δnd ₁ of the liquid crystal in the portion for performing the transmissive display is Since the light from the backlight passes through the liquid crystal layer only once, 1 × Δnd ₁ is obtained.

  In this way, the reflective display area and the transmissive display area have different retardation values, but when controlling the orientation of the liquid crystal molecules in the liquid crystal layer, an electric field is applied to the liquid crystal with the same drive voltage in each display mode. The alignment is controlled, and the liquid crystal in different display forms, in other words, the liquid crystal with different retardation in the transmissive display area and the reflective display area is aligned with the same driving voltage, so that high contrast display is achieved. There was a case that could not get.

  Therefore, a technique has been proposed in which an acrylic resin is formed on the upper side of the lower substrate in the reflective display region, the liquid crystal layer thickness is made smaller than that in the transmissive display region, and the retardation is made uniform. In this case, the acrylic resin layer for controlling the layer thickness of the liquid crystal layer has a structure in which the layer thickness is different between the reflective display region and the transmissive display region. Therefore, the liquid crystal layer also has a step near the boundary between the regions. When a step is generated in the liquid crystal layer in this way, the liquid crystal alignment is disturbed at the step, and disclination may occur, which may cause a display defect such as a decrease in contrast.

  The present invention has been made to solve the above-described problem, and as a transflective liquid crystal display device, the occurrence of disclination can be suppressed near the boundary between the reflective display area and the transmissive display area. An object of the present invention is to provide a liquid crystal display device having a configuration and capable of obtaining a bright and high-contrast display, and an electronic apparatus including the liquid crystal display device.

  In order to solve the above problems, a liquid crystal display device of the present invention is a liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates, and is used for a reflective display region used for reflective display and a transmissive display. The liquid crystal layer in the reflective display region and the liquid crystal layer in the transmissive display region are different in thickness between at least one of the pair of substrates and the liquid crystal layer. An insulating layer is formed at least in the reflective display region, and the insulating layer has an inclined region having an inclined surface so that its own layer thickness continuously changes in the vicinity of the boundary between the reflective display region and the transmissive display region. It is characterized by including.

  In this case, since the insulating layer is formed at least in the reflective display area, the liquid crystal layer thickness in the reflective display area is smaller than the liquid crystal layer thickness in the transmissive display area (functions as a means for thinning the reflective liquid crystal layer). However, even when the thickness of the liquid crystal layer through which the light contributing to the display passes is different between the reflective display and the transmissive display, the difference in retardation can be made small or zero. Furthermore, since the insulating layer includes an inclined region having an inclined surface so that its layer thickness continuously changes in the vicinity of the boundary between the reflective display region and the transmissive display region, the reflective display region and the transmissive display region are provided. Therefore, the step of the insulating layer does not occur in the vicinity of the boundary, and therefore the step of the liquid crystal layer does not easily occur in the vicinity of the boundary, the liquid crystal alignment is hardly disturbed, and the occurrence of disclination is suppressed.

  The insulating layer can be mainly composed of a light-transmitting insulating material such as acrylic resin, and the liquid crystal layer is disposed on the surface side where the inclined surface of the insulating layer is formed. The layer thickness may be continuously changed near the boundary between the reflective display region and the transmissive display region along the inclined surface. In addition, the reflective display area may be formed with a reflective layer capable of reflecting incident light. For example, the reflective display area may have a different side from the side on which external light such as sunlight or illumination light enters. A reflective layer may be formed between the substrate (inner side substrate) and the liquid crystal layer. In this case, external light is reflected by the reflective layer after passing through the liquid crystal layer, passes through the liquid crystal layer again, passes through the liquid crystal layer a total of two times, and is used for display, and is incident from the inner side substrate. Since the light source light (backlight) passes through the liquid crystal layer once and is used for display, the structure of the present invention is adopted, and the thickness of the liquid crystal layer in the reflective display region is changed to the transmissive display region by the insulating layer, for example. By setting the thickness of the liquid crystal layer to about half the thickness, the retardation value in each region can be made substantially equal.

  In addition, the insulating layer includes a reflection-side flat region that is located in the reflection display region and has a substantially uniform layer thickness and a flat surface on the liquid crystal layer side, and the inclined layer is adjacent to the reflection-side flat region. A region may be formed. In this case, stable liquid crystal alignment is obtained in the reflection-side flat region, and the step of the insulating layer does not occur in the adjacent inclined region as described above. Therefore, the step of the liquid crystal layer in the vicinity of the boundary is difficult to occur. Disturbance of liquid crystal alignment is less likely to occur. Note that even in the transmissive display region, by making the surface in contact with the liquid crystal layer flat, it is possible to realize uniform liquid crystal alignment in which disclination hardly occurs.

  When the inclined surface is formed in a planar shape or a curved surface, and the layer thickness of the reflection-side flat region is d, the tangent of the inclined surface at a position where the layer thickness of the inclined region is d / 2, the flat surface, Can be set to 10 ° to 50 °. In this case, good display can be obtained. For example, when the angle α exceeds 50 °, disclination may occur near the boundary between the reflective display area and the transmissive display area, that is, in the inclined area. As a result, the brightness of the display may decrease. On the other hand, when the angle α is less than 10 °, the liquid crystal alignment defect is hardly generated, but the flat area is reduced, and the liquid crystal layer thickness of the reflective display area and the transmissive display area is different from the desired thickness. The brightness may be lower than when disclination occurs. The angle α is preferably about 30 ° to 45 °.

Further, the reflective layer may include an opening, a transmissive display area may be formed in the opening, and an opening edge of the opening may be included in the inclined area.
That is, by including the opening edge of the opening of the reflective layer, which becomes the boundary between the reflective display region and the transmissive display region, in the inclined region, the layer thickness of the liquid crystal layer in both the reflective display region and the transmissive display region. It is possible to include a region (inclined region) in which changes occur, and therefore, the retardation difference can be reduced. In addition, by providing the opening edge of the opening at the position of d / 2, it is possible to further reduce the difference in retardation, and it is possible to obtain a good display with little reduction in contrast.

  Next, in the case where the outside light incident side of the pair of substrates is the upper substrate, and the other is the lower substrate, the reflective display area includes the reflective layer, the insulating layer, the lower electrode, and the lower substrate side. The liquid crystal layer and the upper electrode may be included at least in this order. Further, the reflective display region may include a reflective layer, a lower electrode, a liquid crystal layer, an upper electrode, and an insulating layer in this order from the lower substrate side.

  Here, examples of the lower electrode and the upper electrode include transparent electrodes such as ITO (Indium-Tin-Oxide). In such a configuration, external light incident from the upper substrate (display side substrate or outer substrate) reaches the reflective layer via at least the upper electrode, the liquid crystal layer, the lower electrode, and the insulating layer, and is reflected by this reflective layer. Then, the light is emitted to the outside through a similar process, and a reflective display is realized.

  In the transmissive display region, the lower electrode, the liquid crystal layer, and the upper electrode may be stacked in this order from the lower substrate (backlight side substrate or inner substrate) side. Thus, when the insulating layer is not provided in the transmissive display region, the liquid crystal layer is relatively thicker than the reflective display region in which the insulating layer is provided, and the liquid crystal layer thickness for the reciprocating display is reduced. It can be ensured in the transmissive display. Therefore, the same degree of retardation can be secured in the transmissive display and the reflective display.

  Next, a color filter is provided between the pair of substrates, and the spectral characteristics of the color filter are different between the reflective display region and the transmissive display region. The color purity of the color filter in the transmissive display region is higher than that of the reflective display region. Can also be relatively high. In transmissive display, transmitted light is used for display after passing through the color filter once. In reflective display, external light passes through the color filter once and twice when reflected, so that the above-mentioned As described above, by making the color purity of the color filter relatively higher than that of the reflective display region in the transmissive display region, it is possible to make the color density of the transmissive display and the reflective display comparable.

  In addition, irregularities may be formed on the surface of the lower substrate on the liquid crystal layer side (upper substrate side). That is, for example, the reflective layer can be formed on the upper layer of the lower substrate on which the unevenness is formed. In this case, since the external light is reflected with scattering by the unevenness formed on the lower substrate, Contrast reflection display can be performed.

  Next, an electronic apparatus according to the present invention includes the liquid crystal display device having the above-described configuration. According to this configuration, it is possible to switch between transmissive display and reflective display, and both the transmissive display and the reflective display can be bright and high-contrast display. An electronic device capable of realizing bright and high-contrast display even in the vicinity of the boundary of the region can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 shows a first embodiment in which the configuration of the present invention is applied to an active matrix type liquid crystal display device. The liquid crystal display device A of this first embodiment is vertically arranged as shown in the sectional structure of FIG. It has a basic structure in which a liquid crystal layer 3 is sandwiched between substrates 1 and 2 made of transparent glass or the like disposed so as to face each other. Although omitted in the drawings, a sealing material is actually interposed on the peripheral edge side of the substrates 1 and 2, and the liquid crystal layer 3 is surrounded by the substrates 1 and 2 and the sealing material. The substrate 1 is sandwiched between the substrates 1 and 2. A backlight 4 including a light source, a light guide plate, and the like is provided further below the lower substrate 2.

  A phase difference plate 12 and a polarizing plate 13 are disposed on the upper surface side (observer side) of the upper substrate 1, and the phase difference plate 14 and polarization are also disposed on the lower surface side (internal light source side) of the lower substrate 2. A plate 15 is arranged. The polarizing plates 13 and 15 transmit only one direction of linearly polarized light with respect to the external light incident from the upper surface side and the light of the backlight 4 incident from the lower surface side. The linearly polarized light transmitted through 15 is converted into circularly polarized light (including elliptically polarized light). Therefore, the polarizing plates 13 and 15 and the retardation plates 12 and 14 function as circularly polarized light incident means. In this embodiment, the side having the backlight 4 is the lower side, and the side on which one external light is incident is the upper side. The substrate 1 is sometimes referred to as the upper substrate 1 and the substrate 2 is sometimes referred to as the lower substrate 2. .

  On the other hand, a transparent electrode 5 made of ITO (Indium-Tin-Oxide) or the like is formed on the liquid crystal layer 3 side of the upper substrate 1 through a color filter 10. An alignment film 11 is formed so as to cover the electrode 5. In addition, a reflective layer 16 is formed on the lower substrate 2 on the liquid crystal layer 3 side, and the reflective layer 16 includes openings 16a at predetermined intervals, and the openings 16a are in the horizontal direction in FIG. A plurality of pixels are formed in such a manner that they are divided in a rectangular shape in plan view so as to correspond to the transmissive display area while being spaced apart from each other in the direction. The reflective layer 16 is made of a light-reflective metal material such as Al or Ag, that is, has a rectangular frame shape in plan view, and the alignment film 11 has a predetermined thickness relative to a polymer material film such as polyimide. What was rubbed is used.

  Further, the surface of the lower substrate 2 on the liquid crystal layer 3 side is subjected to frost processing to form an uneven portion 2e, and the surface of the reflective layer 16 on the liquid crystal layer 3 side also forms an uneven portion 16e along the uneven portion 2e. is doing. Such uneven formation on the substrate 2 is formed, for example, by applying a resist on a glass substrate to be the substrate 2 and then performing an etching process using hydrofluoric acid, and performing a photolithography process for removing the resist after the etching process. Can do.

  On the upper layer side of the reflective layer 16, a liquid crystal layer thickness control layer (insulating layer) 22 b for forming a region having a large layer thickness and a region having a small layer thickness for the liquid crystal layer 3 is projected at predetermined intervals. Is formed. The liquid crystal layer thickness control layer (insulating layer) 22b is mainly composed of a translucent insulating material such as acrylic resin, and the upper surface of the reflective layer 16 is covered by the liquid crystal layer thickness control layer (insulating layer) 22b. In addition, concave portions 22a are formed between the convex liquid crystal layer thickness control layers (insulating layers) 22b. Further, the liquid crystal layer thickness control layer (insulating layer) 22b includes an inclined region having an inclined surface 24 inclined at an angle of 10 ° to 50 ° from the concave bottom surface 23 that is a valley bottom of the concave portion 22a, and a hill of the convex portion. And a flat region having a flat surface 25 as a part. Accordingly, the liquid crystal layer thickness control layer (insulating layer) 22b has its own layer thickness continuously changing in the plane direction in the inclined region, and its layer thickness is substantially uniform in the plane direction in the flat region. It is made into the composition. The inclined region and the flat region are adjacent to each other so that the inclined surface and the flat surface are continuous.

The transparent electrode 6 is formed on the surface of the liquid crystal layer thickness control layer (insulating layer) 22b on the liquid crystal layer 3 side and the bottom surface of the concave portion 22a (that is, the surface on which the concave portion 22a of the lower substrate 2 is formed) 23, An alignment film 7 is formed on the transparent electrode 6 so as to cover the electrode.
For example, ITO (Indium-Tin-Oxide) or the like can be used as the transparent electrode 6, and the alignment film 7 can be formed by performing a predetermined rubbing process on a polymer material film such as polyimide. The transparent electrode 6 is driven and controlled by a thin film transistor 17 as a switching element shown in FIG. 2. Therefore, in this embodiment, the lower transparent electrode 6 is a pixel electrode, the upper transparent electrode 5 is a counter electrode, and the lower substrate 2 is The element substrate and the upper substrate 1 are used as a counter substrate. In this case, the switching element such as the thin film transistor 17 can be formed on the lower substrate 2 side, for example, but is not shown in the present embodiment.

  Next, in the liquid crystal display device A of the present embodiment, a region used for display in the liquid crystal layer 3 includes a reflective display region R and a transmissive display region T, and these display portions are formed with different liquid crystal layer thicknesses. Yes. Specifically, the liquid crystal layer thickness control layer (insulating layer) 22b described above is formed in the reflective display region R, and the concave portion 22a is formed in the transmissive display region T. This liquid crystal layer thickness control layer (insulating layer) The thickness of the liquid crystal layer 3 in the reflective display region R is configured to be smaller than the thickness of the liquid crystal layer 3 in the transmissive display region T based on the formation of the (layer) 22b. That is, the liquid crystal layer thickness in the reflective display region R is reduced based on the thickness of the liquid crystal layer thickness control layer (insulating layer) 22b, and the liquid crystal layer thickness control layer (insulating layer) 22b is the liquid crystal layer 3 in the reflective display region R. Functions as a means for thinning the reflection-side liquid crystal layer.

  Here, the reflective layer 16 is formed in the reflective display region R, and the opening edge of the opening 16a of the reflective layer 16 is the boundary between the reflective display region R and the transmissive display region T. Therefore, the transmissive display region T is formed in the opening 16a, light is incident from the backlight 4 through the opening 16a, and the incident light passes through the liquid crystal layer 3 and is used for transmissive display. Yes.

  In addition, the opening edge of the opening 16a in the reflective layer 16 is formed in an inclined region having the inclined surface 24 of the liquid crystal layer thickness control layer (insulating layer) 22b. It is configured to include a boundary portion with the transmissive display region T. Therefore, the layer thickness of the liquid crystal layer 3 continuously changes in the vicinity of the boundary between the reflective display region R and the transmissive display region T along the inclined surface 24 of the inclined region. Specifically, the layer thickness of the liquid crystal layer 3 positioned on the bottom surface 23 or the inclined surface 24 of the concave portion 22a is the liquid crystal layer positioned on the flat surface 25 of the liquid crystal layer thickness control layer (insulating layer) 22b. The layer thickness is larger than 3.

  The inclined surface 24 is formed in a flat shape in this embodiment, and the inclined angle is 10 ° to 50 °. However, as shown in FIG. 8, it may be formed in a gently curved curved surface shape. It is. In this case, the inclination angle is an angle α formed by the flat surface 25 and the tangent to the inclined surface at a position where the layer thickness of the inclined region is d / 2, where d is the layer thickness of the flat region including the flat surface 25. The liquid crystal layer thickness control layer (insulating layer) 22b is formed so that the angle α is 10 ° to 50 °. In the present embodiment, for example, the layer thickness d of the flat region is 2 μm, and the inclined width (width in the plane direction) 1 of the inclined region is about 10 μm.

  Next, FIG. 2 is a schematic plan view of the electrode 6 of the liquid crystal display device A shown in FIG. 1. In the liquid crystal display device A, the display area is composed of a large number of pixels g as shown in FIG. Each pixel g is partitioned by a substantially square portion in which three vertically long electrodes 6 are assembled when the electrode 6 is viewed in plan view. Since the liquid crystal display device A of the present embodiment has a structure premised on color display, specifically, one pixel g having a substantially square shape in plan view partitioned by the three electrodes 6 shown in FIG. It is divided into three dots g1, g2, and g3. And the rectangular recessed part 22a is formed in the center part of the electrode 6 corresponding to these dots g1-g3, respectively, and the electrode 6 is also formed in the bottom side of these recessed parts 22a. The rectangular concave portion 22a is provided with the above-described inclined surface 24 in each part of the four sides, and the inner edge thereof is a transmissive display region T.

  Here, the electrode 6 includes a transmissive display electrode 6b provided at a position corresponding to the recess 22a, specifically, a position extending from the bottom of the recess 22a to the middle of the inclined region (specifically, the opening edge 16a of the reflective layer 16). And functionally divided into a position corresponding to the layer thickness d of the flat region (see FIG. 8), specifically, the reflective display electrode 6a provided on the upper surface of the liquid crystal layer thickness control layer (insulating layer) 22b. It is supposed that each contributes to transmissive display and reflective display. The transmissive display electrode 6a is located inside the opening 16a shown in FIG. 1, and the reflective display electrode 6b is a liquid crystal layer thickness control layer (insulating layer) on the upper side of the reflective layer 16 having the opening 16a. Layer) 22b.

  The size of the opening 16a formed in the reflective layer 16 is such that the vertical width and horizontal width of each dot are about a fraction of the size of any one of the dots g1, g2, and g3. Formed. Further, the horizontal width of each dot g1, g2, g3 is set to 80 μm, for example, and the horizontal width of the pixel g constituted by each dot g1, g2, g3 is set to 240 μm, for example, and each dot g1, g2, g3 The vertical width, that is, the vertical width of the pixel g is, for example, 240 μm. The opening width of the opening 16a can be set to, for example, 30 μm, and the opening length can be set to, for example, about 100 μm.

  A thin film transistor 17 as a switching element for driving the electrode 6 is formed in a corner portion around each dot, and a gate line 18 and a source line 19 for supplying power to the thin film transistor 17 are further wired. In the present embodiment, the thin film transistor 17 is provided as a switching element. However, a two-terminal linear element or a switching element having another structure may be applied as the switching element.

  In addition, the colored portions of the color filter 10 (see FIG. 1) are arranged so as to correspond to the planar positions of the dots g1, g2, and g3. The color filter 10 includes colored portions 10A, 10B, and 10C colored in one of “R (red), G (green), and B (blue)”, and a light shielding layer (black) disposed at the boundary between these colored portions. Matrix) 10a. In the structure of the color filter 10 shown in FIG. 1, the colored portions are repeatedly arranged in the order of 10A (red), 10B (green), and 10C (blue). However, the arrangement order of these colored portions is an example. Any arrangement such as a random arrangement, a mosaic arrangement, or an arrangement in another order may be used.

  Next, functions and effects of the transflective liquid crystal display device A having the structure shown in FIGS. 1 and 2 will be described. When performing reflective display in the liquid crystal display device A, light incident from the outside of the device is used, and this incident light is transmitted from the outside of the substrate 1 through the color filter 10, the electrode 5, and the alignment film 11. It leads to the layer 3 side.

  Here, in the reflective display region R, after the incident light passes through the liquid crystal layer 3, it passes through the alignment film 7, the electrode 6, and the liquid crystal layer thickness control layer (insulating layer) 22 b and is reflected by the reflective layer 16. The Then, after the reflected light again passes through the liquid crystal layer thickness control layer (insulating layer) 22b, the electrode 6, the alignment film 7, and the liquid crystal layer 3, the alignment film 11, the electrode 5, the color filter 10, the substrate 1, By returning to the outside of the apparatus through the phase difference plate 12 and the polarizing plate 13, it reaches the observer and a reflective color display is performed. On the other hand, in the transmissive display unit T, the incident light from the outside passes through the liquid crystal layer 3, then passes through the alignment film 7 and the electrode 6, and further passes through the opening 16 a of the reflective layer 16. The light that has passed through the opening 16 a passes through the lower substrate 2 and the retardation plate 12 and is then absorbed by the polarizing plate 13. In such a reflective color display, the liquid crystal layer 3 is controlled in alignment by the electrodes 5 and 6 to change the transmittance of light passing through the liquid crystal layer 3 to perform bright and dark display. .

  When performing transmissive display, light emitted from the backlight 4 enters through the polarizing plate 15, the phase difference plate 14, and the substrate 2. In this case, in the transmissive display region T, light incident from the substrate 2 is the electrode 6, the alignment film 7, the liquid crystal layer 3, the alignment film 11, the electrode 5, the color filter 10, the substrate 1, the retardation plate 12, and the polarizing plate 13. In this order, transmission color display is performed. On the other hand, in the reflective display region R, light incident from the substrate 2 is reflected by the reflective layer 16, and the reflected light passes through the phase difference plate 14 and is then absorbed by the polarizing plate 15. Even in such a transmissive color display, by controlling the orientation of the liquid crystal of the liquid crystal layer 3 by the electrodes 5 and 6, bright and dark display can be performed by changing the transmittance of light passing through the liquid crystal layer 3.

  In these display forms, incident light passes through the liquid crystal layer 3 twice in the reflection type display form, but light emitted from the backlight 4 passes through the liquid crystal layer 3 only once with respect to transmitted light. When the retardation of the liquid crystal layer 3 is taken into consideration here, when the same voltage is applied from the electrodes 5 and 6 in the reflective display mode and the transmissive display mode, the liquid crystal transmittance is changed due to the difference in the liquid crystal retardation. Make a difference. However, in the structure of this embodiment, since the liquid crystal layer thickness control layer (insulating layer) 22b is provided in the reflective display region R, that is, the reflective display region R that includes the reflective layer 16 shown in FIG. The thickness of the liquid crystal layer 3 in the transmissive display region T, which is a region corresponding to the opening 16a shown in FIG. 1, is larger than the thickness of the liquid crystal layer 3 in the reflective display region R. The state relating to the transmissive display and the reflective display of the liquid crystal layer 3 in the reflective display region R and the transmissive display region T, that is, the distance through which light passes through the liquid crystal layer 3 in each region can be made uniform. Therefore, by forming the liquid crystal layer thickness control layer (insulating layer) 22b, it is possible to make the retardation uniform in the reflective display region R and the transmissive display region T, and both the reflective display and the transmissive display are bright and high-contrast display. It will be obtained.

  Further, in the vicinity of the boundary between the reflective display region R and the transmissive display region T, the layer thickness change of the liquid crystal layer 3 becomes steep, and there is a possibility that a liquid crystal alignment defect occurs. However, in this embodiment, since the liquid crystal layer thickness control layer (insulating layer) 22b is formed with an inclined surface in the vicinity of the boundary of each region, a steep layer thickness change of the liquid crystal layer is eliminated, and liquid crystal alignment defects are unlikely to occur. It has a configuration. Therefore, the liquid crystal display device A of the present embodiment is a transflective liquid crystal display device, which is bright and high in both reflective display and transmissive display based on the formation of the liquid crystal layer thickness control layer (insulating layer) 22b. Contrast display can be performed, and in particular, a display device in which a display defect or the like in the vicinity of the boundary between the reflective display region and the transmissive display region hardly occurs.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIG. In addition, about the same code | symbol as 1st Embodiment shown in FIG. 1, description is abbreviate | omitted as having the same structure unless there is particular notice. In the liquid crystal display device B of the second embodiment, a translucent uneven layer 16b and a reflective main body layer 16c are formed on the lower substrate (backlight side substrate) 2 in the reflective display region R.

  The translucent uneven layer 16b is mainly composed of an acrylic resin, and the surface layer portion (the liquid crystal layer side surface) is uneven, and the uneven portion is also formed in the reflective main body layer 16c according to the unevenness. . By forming irregularities on the reflection main body layer 16c in this way, it is possible to reliably scatter and reflect light incident from the outside. In addition, this uneven | corrugated | grooved part is made into the surface roughness of the range of 0.5-0.8 micrometer, and an unevenness | corrugation is formed at random.

  Even in such a liquid crystal display device B, it is possible to take a display form using transmissive display and reflective display as in the liquid crystal display device A of the first embodiment. Also in this case, since the thickness of the liquid crystal layer is changed between the transmissive display region T and the reflective display region R in the same manner as in the first embodiment, the same effect can be obtained. In the layer thickness control layer (insulating layer) 22b, since an inclined region having an inclined surface is formed, a liquid crystal alignment defect or the like hardly occurs in the same region. Further, in the second embodiment, since the light-transmitting uneven layer 16b for forming random unevenness is formed on the reflective main body layer 16c, various incident lights are reflected on the reflective main body layer 16c when performing reflective display. Therefore, it is possible to obtain a reflective display with a wider viewing angle.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to FIG. In addition, about the same code | symbol as 1st Embodiment shown in FIG. 1, description is abbreviate | omitted as having the same structure unless there is particular notice. In the liquid crystal display device C according to the third embodiment, the reflective layer 16 is formed on the upper layer side (the liquid crystal layer 3 side) of the lower substrate 2, the upper layer side of the reflective layer 16, and the reflective layer 16. The color filter 10 is formed so as to fill the opening 16a. The liquid crystal layer thickness control layer (insulating layer) 22b, the electrode 6, the alignment film 7, and the liquid crystal layer 3 are formed in the reflective display region R on the color filter 10, and the electrode 6, the alignment film 7, and the liquid crystal The layer 3 is formed in the transmissive display region T.

  Even in such a liquid crystal display device C, it is possible to adopt a display form using transmissive display and reflective display, similar to the liquid crystal display device A of the first embodiment. In this case as well, the liquid crystal layer thickness control layer 22b is formed in the reflective display region R, and the thickness of the liquid crystal layer in the transmissive display region T and the reflective display region R is the same as in the first embodiment. The same effect can be obtained. Furthermore, since the liquid crystal layer thickness control layer (insulating layer) 22b has an inclined region having an inclined surface, the liquid crystal alignment defect or the like hardly occurs in the region.

[Fourth Embodiment]
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG. In addition, about the same code | symbol as 1st Embodiment shown in FIG. 1, description is abbreviate | omitted as having the same structure unless there is particular notice. In the liquid crystal display device D of the fourth embodiment, a color filter 10 made of R (red), G (green), and B (blue) is formed on the inner surface of the upper substrate 1, and the liquid crystal layer of the color filter 10 is further formed. On the third side, a liquid crystal layer thickness control layer (insulating layer) 22b is formed. That is, the liquid crystal layer thickness control layer (insulating layer) 22b, the electrode 5, and the alignment film 11 are formed between the color filter 10 and the liquid crystal layer 3 provided on the inner surface of the upper substrate 1 on the liquid crystal layer side.

  Even in such a liquid crystal display device D, as in the liquid crystal display device A of the first embodiment, the liquid crystal layer thickness control layer 22b is formed in the reflective display region R, and the liquid crystal layer 3 in the transmissive display region T is formed. Since the thickness is larger than the thickness of the liquid crystal layer 3 in the reflective display region R, an effect equivalent to that of the first embodiment can be obtained. In addition, since an inclined region having an inclined surface is formed in the liquid crystal layer thickness control layer (insulating layer) 22b, a liquid crystal alignment defect or the like hardly occurs in the region.

[Fifth Embodiment]
The fifth embodiment of the present invention will be described below with reference to FIGS. In addition, about the same code | symbol as 1st Embodiment shown in FIG. 1, description is abbreviate | omitted as having the same structure unless there is particular notice. 6 and 7 show a fifth embodiment in which the transflective liquid crystal display device according to the present invention is applied to a simple matrix type liquid crystal display device. The liquid crystal display device E according to the fifth embodiment has a basic structure in which a liquid crystal layer 3 is sandwiched between substrates 1 and 2 made of transparent glass and the like that are vertically opposed to each other as in the cross-sectional structure shown in FIG. This is the same as the previous embodiments, and a backlight 4 is provided on the lower side of the lower substrate 2.

  In the liquid crystal display device E shown in FIG. 6, a transparent electrode 50 having a strip shape in plan view extends on the substrate 1 on the liquid crystal layer 3 side so as to extend in the direction perpendicular to the paper surface of FIG. It is formed so as to be spaced apart and correspond to the display area. On the other hand, on the liquid crystal layer 3 side of the substrate 2, a plurality of strip-shaped electrodes 60 in plan view extend in the left-right direction in FIG. 6 and are spaced apart from each other in the vertical direction in FIG. The upper and lower electrodes 50 and 60 are arranged so as to intersect with each other at 90 ° in plan view.

  In the liquid crystal display device E, the display area is configured by a collection of a large number of pixels g. Each pixel g is formed by a portion where the electrodes 50 and 60 intersect when the electrodes 50 and 60 are viewed in plan as shown in FIG. Partitioned. Since the liquid crystal display device E of the present embodiment has a structure premised on color display, specifically, one pixel g having a substantially square shape in plan view partitioned by a chain line shown in FIG. Each pixel g is divided into dots g 1, g 2, and g 3 that are divided by one electrode 50 and one electrode 60. And the rectangular recessed part 22a is formed in the center part of the electrode 60 corresponding to these dots g1-g3 separately, and the position corresponding to the recessed part 22a is the transparent display electrode 60b similarly to 1st Embodiment. The position corresponding to the convex liquid crystal layer thickness control layer (insulating layer) 22b surrounding the concave portion 22a is defined as the reflective display region R having the reflective display electrode 60a. In the case of a structure corresponding to black and white display instead of assuming color display as in this embodiment, the color filter 10 may be omitted by using the electrodes 50 and 60 as strip-like electrodes having the same width.

  Even in such a liquid crystal display device E, it is possible to take a display form using a transmissive display and a reflective display as in the liquid crystal display device A of the first embodiment. Also in this case, the liquid crystal layer thickness control layer (insulating layer) 22b is formed in the reflective display region R, and the thickness of the liquid crystal layer is changed between the transmissive display region T and the reflective display region R in the first embodiment. Since it is changed similarly to the case of, the same effect can be obtained. Furthermore, since the liquid crystal layer thickness control layer (insulating layer) 22b has an inclined region having an inclined surface, the liquid crystal alignment defect or the like hardly occurs in the region.

[Modification common to each embodiment]
Next, in the liquid crystal display devices A to E of the first to fifth embodiments as described above, the spectral characteristics of the color filter 10 are different between the reflective display region R and the transmissive display region T. be able to. Specifically, as shown in FIGS. 9 and 10, the color purity of the color filter 10 in the transmissive display region T (the transmissive CF specification shown in FIG. 9) is changed to the reflective display region R (the reflective CF specification shown in FIG. 10). ) Can be relatively higher. For example, when transmissive display is performed, transmitted light is used for display after passing through the color filter 10 once. On the other hand, when reflective display is performed, external light is incident on the color filter and reflected once. Since it passes twice in total, the color purity of the color filter 10 in the transmissive display area T is made higher than that in the reflective display area R in the transmissive display area T as shown in FIGS. It is possible to make the shades comparable.

[Electronics]
Examples of electronic devices provided with the liquid crystal display device of the above embodiment will be described.
FIG. 11A is a perspective view showing an example of a mobile phone. In FIG. 11A, reference numeral 500 denotes a mobile phone body, and reference numeral 501 denotes a liquid crystal display unit using the liquid crystal display devices A to E.

  FIG. 11B is a perspective view illustrating an example of a portable information processing apparatus such as a word processor or a personal computer. In FIG. 11B, reference numeral 600 denotes an information processing apparatus, reference numeral 601 denotes an input unit such as a keyboard, reference numeral 603 denotes an information processing apparatus body, and reference numeral 602 denotes a liquid crystal display unit using the liquid crystal display devices A to E described above. ing.

  FIG. 11C is a perspective view showing an example of a wristwatch type electronic device. In FIG. 11C, reference numeral 700 denotes a watch body, and reference numeral 701 denotes a liquid crystal display unit using the liquid crystal display devices A to E described above.

  As described above, since the electronic apparatus illustrated in FIG. 11 includes the liquid crystal display unit using the liquid crystal display devices A to E according to the above-described embodiments, the electronic apparatus having a bright and high-contrast display unit under various environments. Can be realized. In addition, it is possible to realize an electronic device including a display portion with few display defects even at the boundary between the reflective and transmissive display areas.

[Example]
Next, in order to confirm the effect of the above embodiment, the following evaluation was performed. That is, as shown in FIG. 8, the thickness d of the flat region of the liquid crystal layer thickness control layer 22b and the region width (horizontal width in the plane direction) 1 of the inclined region are changed as shown in Tables 1 and 2, A liquid crystal display device A according to the first embodiment having a different angle α was prepared.

Thus, about each liquid crystal display device from which inclination | tilt angle (alpha) differs, the alignment uniformity of the liquid crystal in the liquid crystal layer 3, and the brightness (cd / m < ² >) in a transmissive display were evaluated. The alignment uniformity was evaluated as x when a discontinuous portion was observed in the alignment state by microscopic observation, and ◯ when it was not observed. As a result, it was confirmed that the liquid crystal alignment was uneven and the occurrence of disclination was observed for those with inclination angles α exceeding 50 °, 63.4 °, 68.2 °, 84.3 °, and 87.1 °. The brightness of the transmissive display was 31 cd / m ² or less, which was relatively low. In addition, when the tilt angle α is less than 10 ° and 7.6 ° and 5.7 °, the liquid crystal orientation is uniform, but the brightness in transmissive display is 30 cd / m ² or less and relatively low. Met.

  On the other hand, when the inclination angle α is 10 ° to 50 °, the alignment of the liquid crystal is excellent in uniformity, and the brightness in transmissive display is relatively bright. Therefore, it is confirmed that the liquid crystal display device including the liquid crystal layer thickness control layer (insulating layer) 22b having an inclination angle of 10 ° to 50 ° is excellent in display characteristics with less liquid crystal alignment disorder and less disclination. It was.

[The invention's effect]
As described above in detail, according to the present invention, since the liquid crystal layer thickness control layer (insulating layer) is provided at least in the reflective display region in order to reduce the thickness of the liquid crystal layer in the reflective display region, It is possible to make the retardation uniform in the display area and the transmissive display area, and a bright and high-contrast display can be obtained for both the reflective display and the transmissive display. In addition, since the liquid crystal layer thickness control layer (insulating layer) is configured with an inclined surface to continuously change its own layer thickness in the vicinity of the boundary between the reflective display region and the transmissive display region, The configuration was such that there was no sharp change in the thickness of the liquid crystal layer in the vicinity. Therefore, liquid crystal alignment is hardly disturbed near the boundary between the reflective display area and the transmissive display area, and a bright and high-contrast display can be obtained. Note that the liquid crystal layer thickness control layer (insulating layer) can also be provided in the transmissive display region, in which case the layer is smaller than the liquid crystal layer thickness control layer (insulating layer) formed in the reflective display region. It only needs to be thick.

The figure which shows typically the partial cross-section of the liquid crystal display device which concerns on the 1st Embodiment of this invention. FIG. 2 is a partially enlarged plan view showing an enlarged reflection layer of the liquid crystal display device of FIG. 1. The figure which shows typically the partial cross-section of the liquid crystal display device which concerns on the 2nd Embodiment of this invention. The figure which shows typically the partial cross-section of the liquid crystal display device which concerns on the 3rd Embodiment of this invention. The figure which shows typically the partial cross-section of the liquid crystal display device which concerns on the 4th Embodiment of this invention. The figure which shows typically the partial cross-section of the liquid crystal display device which concerns on the 5th Embodiment of this invention. FIG. 7 is a partially enlarged plan view showing an enlarged reflection layer of the liquid crystal display device of FIG. 6. Explanatory drawing which shows the inclination-angle in the inclination area | region of a liquid-crystal layer layer thickness control layer (insulating layer). FIG. 6 is a diagram illustrating spectral characteristics of a color filter used for transmissive display. The figure which shows the spectral characteristic of the color filter used for reflection display. FIG. 14 is a perspective view illustrating some examples of the electronic apparatus according to the invention.

Explanation of symbols

  A to E Liquid crystal display device 1 Upper substrate 2 Lower substrate 3 Liquid crystal layer 10 Color filter 16 Reflective layer 16a Opening 22b Liquid crystal layer thickness control layer (insulating layer) 24 Inclined surface 25 Flat surface R Reflective display region T Transmissive display region

Claims (3)

Liquid crystal layer is sandwiched between a pair of substrates, a reflective display area used for reflection display, the liquid crystal display device comprising a transmissive display area used for transmissive display,
At least one substrate of the pair of substrates, the liquid crystal layer convex insulating layer made different from the thickness of in the transmissive display region and the layer thickness of the liquid crystal layer in the reflective display region is formed Thus, a concave portion is formed, whereby a bottom surface of the concave portion, an inclined surface in which the thickness of the insulating layer is continuously changed from the bottom surface of the concave portion, and an upper surface of the insulating layer are formed,
The bottom surface of the concave portion corresponds to the transmissive display region, the top surface of the insulating layer corresponds to the reflective display region, a reflective layer is provided in the reflective display region, and the edge of the reflective layer is the inclined surface. Located in an inclined area containing
The pair of the other substrate of the substrate, a liquid crystal display device comprising the color filters of the color purity in the transmissive display region is set higher than the color purity of the reflective display region is disposed. The inclined surface is formed in a planar shape or a curved surface, and when the thickness of the insulating layer formed in the reflective display region is d, the thickness of the insulating layer in the inclined region is d / 2. 2. The liquid crystal display device according to claim 1 , wherein an angle α formed between the tangent line of the inclined surface and the flat surface at a position of 10 ° to 50 °. An electronic apparatus comprising the liquid crystal display device according to claim 1 or 2.

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