JP4307799B2 - Reflector and reflective liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention reflectsBody andThe present invention relates to a reflective liquid crystal display device provided with this reflector.
[0002]
[Prior art]
In general, there are a display form of a liquid crystal display device, a so-called transflective type or a transmissive type provided with a backlight, and a reflective type. The reflective liquid crystal display device is a liquid crystal display device that displays only without using backlight, such as sunlight and illumination light, and is, for example, a portable information terminal that is thin, lightweight, and requires low power consumption. It is used in many cases. In addition, the transflective liquid crystal display device operates in the transmission mode with the backlight turned on in an environment where sufficient external light cannot be obtained, and operates in the reflective mode in which the backlight is not turned on when sufficient external light is obtained. It is often used in portable electronic devices such as mobile phones and notebook personal computers (notebook PCs).
[0003]
The display performance of the reflective liquid crystal display device is required to have bright display performance in the liquid crystal transmission state. In order to realize this display performance, it is important that light incident from the outside is reflected inside the reflection type liquid crystal display device and the scattering performance is controlled again to the light emitted to the outside. Therefore, in the reflection type liquid crystal display device, the liquid crystal display device is provided inside or outside the liquid crystal display device in order to have a function of reflecting incident light from all angles in the display direction (observer side). The reflective liquid crystal display device is configured by a method in which the reflecting plate has scattering performance or a forward scattering method in which a scattering layer is formed inside the liquid crystal display device and light is scattered when passing through the scattering layer.
[0004]
FIG. 8 is a side sectional view showing an example of a conventional reflection type liquid crystal display device in which a reflection plate having scattering performance is provided inside the liquid crystal panel. This reflective liquid crystal display device includes a light-transmitting counter substrate 101, a liquid crystal layer 110, and a light-reflective element substrate 102 in this order as viewed from the incident direction of light. A reflection-type scattering band that reflects and scatters the light Q that has passed through is provided. The scattering band is composed of a reflective plate 130 made of a highly reflective metal film 122 having irregularities 122a on the surface and an insulating layer 128 underneath, and the area per pixel of the reflective plate 130 exhibits highly directional reflection characteristics. The region A is divided into two regions: a region A having a diffusive reflection characteristic, and a region B having a highly diffusive reflection characteristic. In each region, uneven surfaces having different average inclination angles are formed.
This reflective liquid crystal display device can also be used as a transflective type by reducing the thickness of the high reflectivity metal film 122 or by forming transmission pores.
[0005]
FIG. 9 is a diagram showing the reflection characteristics of the reflection plate provided in the reflective liquid crystal display device, and the curve (A) in FIG. 9 is a profile showing the reflection characteristics in the region B in FIG. Curve (B) is a profile showing the reflection characteristics of region A in FIG. The reflection characteristics here are measured by measuring the dependence of the reflected light emission angle by fixing the white light source in the normal direction with respect to the reflector surface, rotating the detector for measuring the reflected light intensity. is there.
The profiles of the reflection characteristics (A) and (B) each show a Gaussian distribution shape centered on the regular reflection angle of the incident light L, and the distribution width of each curve reflects the reflection characteristics of the regions A and B, respectively. It has become. That is, the half width of the profile of the reflection characteristic (B) is wider than the half width of the profile of the reflection characteristic (A).
Further, the reflection characteristic (C) shown in FIG. 9 shows a final reflection characteristic profile of one pixel, and this reflection characteristic (C) is incident in the same manner as the reflection characteristics (A) and (B). A Gaussian distribution shape centering on the regular reflection direction of light is shown, and the half-value width of the profile is an average of one pixel as a whole.
[0006]
[Problems to be solved by the invention]
By the way, when a liquid crystal display device is incorporated in a device that uses an inclined display surface, such as a portable information terminal such as a mobile phone or a notebook PC, as shown in FIG. It is often seen from a direction close to the line direction H. In general, the angle θ formed by the main observation direction α and the normal direction H when the observer (user) looks at the display surface (screen) often has a range of 0 to 20 degrees.
FIG. 10 is an explanatory diagram of a state in which the display unit 100 including the liquid crystal display device of FIG. In FIG. 10, H is a normal to the display unit 100, Q is incident light, ω₀Is an incident angle (for example, 30 degrees). R₁Is the incident angle ω₀And reflected light when the reflection angle ω is equal (regular reflection), R₂Is the reflection angle ω is incident angle ω₀Smaller reflected light, R₃Is the reflection angle ω is incident angle ω₀Larger reflected light.
[0007]
As can be understood from the figure, the observer's viewpoint Ob is the reflected light R close to the normal direction H.₂, More specifically, in a range from the normal direction H to 10 degrees. On the other hand, reflected light R₁, R₃  Is a direction that looks up from the bottom of the display surface and is difficult to see. Therefore, considering the convenience of use by the observer, it is desirable to ensure a wide viewing angle and at the same time increase the reflectivity in the direction where the reflection angle is smaller than the regular reflection.
However, in the conventional reflective liquid crystal display device shown in FIG. 8, the range in which the incident light is reflected is wide, that is, although the light scattering property can be realized, most of the incident light is reflected in the regular reflection and the vicinity thereof. Therefore, the display viewed from the specular reflection and its peripheral direction appears bright, but the display viewed from the other direction appears dark.
Therefore, when viewing the display surface of a mobile phone or the like provided with the conventional reflective display device in the display unit, the observer's viewpoint is concentrated in a direction close to the normal direction H as described above. On the other hand, when viewing a bright display, the display must be viewed from specular reflection and its peripheral direction, and the display surface is viewed from the bottom as described above, which is difficult to see.
[0008]
The present invention has been made to solve the above-described problem, and has a reflection characteristic that the brightness of reflected light is increased in a wide angle range, and the reflection angle of the reflected light is close to an observer's line of sight. An object of the present invention is to provide a reflector that can be approached in a direction.
The present invention also provides a reflective liquid crystal display device having a wide viewing angle characteristic by increasing the brightness of reflected light in a wide angle range and making the reflected angle of the reflected light approach a direction close to the line of sight of the observer. The purpose is to do.
[0009]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention adopts the following configuration.
  The reflector of the present invention is a reflector that reflects incident light, and a plurality of reflective slopes in a stripe shape in plan view are continuously formed on the surface of the substrate, and each of the reflective slopes includes a base of each reflective slope. A first inclined surface located on the end side, a second inclined surface located on the upper end side of each reflective inclined surface and in contact with the first inclined surface and having a larger inclination angle than the first inclined surface; and The reflective slope is an irregular concavo-convex surface, and the concavo-convex surface is irregularly formed with a height of a convex portion or a depth of a concave portion in the reflective slope within a range of 0.3 μm to 3 μm. And the pitch between the adjacent convex portions or the adjacent concave portions is irregularly arranged within a range of 1 μm or more and 30 μm or less, and the inclination angle θ of the first inclined surface is₁Is a constant size within a range of 5 ° to 20 ° with respect to the substrate surface, and the inclination angle θ of the second inclined surface₂Is a constant size within a range of 5 ° to 45 ° with respect to the substrate surface, and the pitch L of the reflective slope is a constant size within a range of 5 μm to 80 μm, and the pitch of the first inclined surface L₁And the pitch of the second inclined surface is L₂L₁And L₂The ratio to L₁: L₂= 1: 1 to 1:10, and the inclination angle θ of the first inclined surface₁And the inclination angle θ of the second inclined surface₂Is 5 ° ≦ (θ₂−θ₁) ≦ 15 °The first and second inclined surfaces are inclined in the same direction along the width direction of the stripe.It is characterized by that.
[0010]
According to such a reflector, the reflective inclined surface is constituted by the first inclined surface and the second inclined surface having a larger inclination angle than the first inclined surface, and the uneven surface is formed on the surface of the reflective inclined surface. As a result, the brightness can be increased in a wide angle range, and the reflection angle of the reflected light can be arbitrarily controlled.
[0011]
In the reflector of the present invention, the inclination angle θ of the first inclined surface with respect to the substrate surface₁Is preferably a certain size within a range of 5 ° to 20 °.
In the reflector of the present invention, the inclination angle θ of the second inclined surface with respect to the substrate surface₂Is preferably a certain size within a range of 5 ° to 45 °.
In the reflector of the present invention, it is preferable that the pitch L of the reflective slope is a constant size within a range of 5 μm to 80 μm.
Here, the pitch L of the reflective slope is the distance from the base end to the upper end of the reflective slope and parallel to the in-plane direction of the substrate surface.
[0012]
Furthermore, in the reflector of the present invention, the pitch of the first inclined surface is set to L.₁And the pitch of the second inclined surface is L₂L₁And L₂The ratio to L₁: L₂= 1: 1-1: 10 is preferable.
Here, the pitch L of the first inclined surface₁Is the distance from the base end to the upper end of the first inclined surface and is parallel to the in-plane direction of the substrate surface, and the pitch L of the second inclined surface₂Means the distance from the base end to the upper end of the second inclined surface and parallel to the in-plane direction of the substrate surface.
The above L, L₁And L₂L = L₁+ L₂It becomes.
[0013]
Moreover, in the reflector of this invention, it is preferable that the said uneven surface is irregularly formed in the range whose height of a convex part or the depth of a recessed part in the said reflective slope is 0.3 micrometer or more and 3 micrometers or less. .
Furthermore, in the reflector of this invention, it is preferable that the said uneven surface is irregularly arrange | positioned within the range whose pitch of the said adjacent convex parts or the adjacent recessed parts is 1 micrometer or more and 30 micrometers or less.
[0016]
Moreover, the reflector of the present invention is the reflector described above, and the profile showing the reflection characteristics of the first and second inclined surfaces shows a Gaussian distribution shape centered on the regular reflection angle of the incident light, The profile showing the reflection characteristics of the reflector is a shape in which the base portions of the profiles of the first and second inclined surfaces overlap each other.
[0017]
  According to such a reflector, since the profile indicating the reflection characteristics of the reflector has a shape in which two Gaussian curves are partially overlapped, the brightness of reflected light can be increased in a wide angle range.
  In the reflector of the present invention, the uneven surface is formed by dispersing fine particles, and an electroforming mold is formed on the surface of the fine particle kneaded layer having a fine uneven surface, and the mold surface of the electroforming mold. Is formed by releasing the mold after being pressed against the surface of the substrate.
[0018]
Next, in the reflective liquid crystal display device of the present invention, an electrode and an alignment film are provided in order from the one substrate side on the inner surface side of one of the substrates facing each other across the liquid crystal layer, and on the inner surface side of the other substrate. The reflection according to any one of the foregoing, wherein an electrode and an alignment film are sequentially provided from the other substrate side, and the liquid crystal cell is provided on the outer surface side of the one substrate or between the one substrate and the electrode provided on the inner surface side thereof. It is characterized by providing a body.
[0019]
According to such a reflective liquid crystal display device, since the above reflector is provided, the reflection characteristic is such that the brightness of the reflected light is high in a wide angle range, and the reflected angle of the reflected light is close to the direction of the observer's line of sight. And a wide viewing angle characteristic can be realized.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.
(First embodiment)
FIG. 1 is a diagram schematically showing a partial sectional structure of a reflective liquid crystal display device according to a first embodiment of the present invention, and FIG. 2 is a perspective view of a reflector according to the present invention. These are the fragmentary sectional views corresponding to the AA line of FIG.
In FIG. 1, the reflective liquid crystal display device includes a first substrate (one substrate) 10 and a second substrate (the other substrate) 20 made of transparent glass and the like which are opposed to each other with a liquid crystal layer 30 interposed therebetween. The two substrates 10 and 20 have a configuration in which they are bonded and integrated with a sealing material (not shown) provided in an annular shape on the peripheral edge portions.
In order on the liquid crystal layer 30 side of the first substrate 10, the reflector 47 according to the present invention, the transparent intervening layer 53, the color filter 13 for performing color display, and the unevenness due to the color filter 13 are flattened. The overcoat film (transparent planarizing layer) 14, the transparent electrode layer 15 for driving the liquid crystal layer 30, and the alignment film 16 for controlling the alignment of the liquid crystal molecules constituting the liquid crystal layer 30 are laminated. ing. In addition, a transparent electrode layer 25, an overcoat film 24, and an alignment film 26 are sequentially stacked on the liquid crystal layer 30 side of the second substrate 20. In addition, the transparent electrode layer 15 and the transparent electrode layer 25 sandwiching the liquid crystal layer 30 are formed in stripes orthogonal to each other, and constitute a simple matrix type liquid crystal device in which the intersection area is a pixel.
[0023]
A liquid crystal cell 35b is configured by the first substrate 10 and the second substrate 20 described above and the respective constituent members provided between the substrates.
On the side opposite to the liquid crystal layer 30 side of the second substrate 20 (the outer surface side of the second substrate 20), a retardation film 27 and a polarizing plate 28 are laminated in this order. The outer surface of the polarizing plate 28 is a display surface 1a.
[0024]
As shown in FIGS. 1 to 3, the reflector 47 according to the present invention is mainly composed of a base material 11 and a particle layer 12 a provided on the surface side of the base material 11.
The substrate 11 is made of a photosensitive resin such as an acrylic resist, and a plurality of reflective inclined surfaces 48 in a stripe shape in plan view are continuously formed on the substrate 11 as shown in FIG.
[0025]
Further, as shown in FIG. 3, each reflective slope 48... Has a first slope 48 c located on the base end 48 a side of each reflective slope 48 and an upper end 48 b side of each reflective slope 48 and the first slope 48 c. A second inclined surface 48d having a larger inclination angle than the first inclined surface 48c is provided in contact with the inclined surface 48c.
Further, a wall surface 48e is provided between two adjacent reflecting slopes 48, 48, and the reflecting slopes 48 are connected to each other by the wall face 48e.
As shown in FIGS. 2 and 3, the first and second inclined surfaces 48c and 48d are inclined in the same direction along the width direction of the stripe (the horizontal direction in FIG. 3).
[0026]
Further, as shown in FIGS. 3 and 4, a particle layer 12a is formed on each reflection slope 48 ..., and the surface of each reflection slope 48 ... is formed as an uneven surface 12 by this particle layer 12a. As shown in FIG. 3, the particle layer 12 a is formed by attaching a large number of light-reflective microparticles 12 b having different particle diameters to the surface of the reflective slope 48.
[0027]
FIG. 5 shows the viewpoint Ob of an observer who observes the display on one side of an incident angle of 30 ° (perpendicular (normal line) standing on the display surface 1a) on the display surface 1a of the reflective liquid crystal display device 1 described above.₁When illuminating external light at an angle formed with the optical axis of the external light illuminated from the opposite side of the light and scanning the observation direction α (light receiving angle) from a perpendicular position (normal position) (0 °) to a predetermined angle The relationship between the reflection angle (°) and the reflectance is shown.
In FIG. 5, the curves shown by the solid line (1) and the broken line (2) are both curves showing the relationship between the reflection angle (°) and the reflectance, and the difference between the two is the first and second slopes described later. Each pitch L of the surfaces 48c, 48d₁, L₂The ratio is changed.
[0028]
As shown in FIG. 5, each profile (solid line (1), broken line (2)) of the reflection characteristic indicating the relationship between the reflection angle (°) and the reflectance of the reflector 47 according to the present invention is two gausses. The profile of the profile indicating the distribution shape is overlapped.
That is, one Gaussian distribution shape has a central reflection angle of (30 ° −2θ).₁) And a profile corresponding to the first inclined surface 48c. The other Gaussian distribution shape has a central reflection angle of (30 ° −2θ).₂And a profile corresponding to the second inclined surface 48d.
[0029]
Since the reflection characteristic of the reflector according to the present invention shows a profile in which the skirt portions of the profiles showing two Gaussian distribution shapes overlap as shown in FIG. 5, the viewing angle can be made wider than that of the conventional reflector.
That is, as shown in FIG. 5, each profile (1), (2) has a reflection angle (30 ° -2θ).₁) And (30 ° -2θ₂), And the portion having the high reflectance is (30 ° −2θ).₁) Higher region as well as (30 ° -2θ₂) Since it extends to a lower region, a high reflectance can be exhibited in an angle range almost twice that of a conventional reflector.
[0030]
Next, as shown in FIG. 3, the inclination angle θ of the first inclined surface 48 c with respect to the substrate surface S is used.₁Is a fixed size within a range of 5 ° to 20 °, and preferably a fixed size within a range of 10 ° to 20 °. The inclination angle θ of the first inclined surface 48c₁Is less than 5 ° or exceeds 20 °, it is not preferable because the reflection angle of the reflected light cannot be made closer to the direction of the observer's line of sight.
[0031]
Similarly, the inclination angle θ of the second inclined surface 48d with the substrate surface S as a reference₂Is a fixed size within a range of 5 ° to 45 °, and preferably a fixed size within a range of 10 ° to 30 °. The inclination angle θ of the second inclined surface 48d₂Is less than 5 ° or exceeds 45 °, it is not preferable because the reflection angle of the reflected light cannot be made closer to the direction of the observer's line of sight.
In particular, the inclination angle θ of the second inclined surface 48d.₂Is the normal direction H of the display surface 1a₁And the observer's main viewing direction α₁Is preferably (30 ° −θ) / 2 with respect to the angle θ formed by the above, because the reflection angle of the reflected light can be adjusted to the line of sight of the observer. Specifically, the angle θ₂Is usually 0 ° to 20 ° from a practical point of view, so θ₂ Is preferably about 15 ° to 5 °.
[0032]
The inclination angle θ of the second inclined surface 48d₂Is the inclination angle θ of the first inclined surface 48c.₁It is preferable to make it larger. More specifically, (θ₂−θ₁) 5 ° ≦ (θ₂−θ₁) ≦ 15 ° is preferable.
(Θ₂−θ₁) Less than 5 ° is not preferable because the two Gaussian distribution shapes shown in FIG. 5 approach each other, the range of the reflection angle of the reflected light is narrowed, and the viewing angle is narrowed.₂−θ₁) Exceeds 15 °, the overlap of the two Gaussian distribution shapes shown in FIG. 5 decreases, and the light receiving angle (30 ° −2θ)₁) And (30 ° -2θ₂) And the display unevenness occurs and display unevenness occurs.
[0033]
Note that the inclination angle of the wall surface 48e with respect to the reference plane S is a constant size within a range of 90 ° to 130 °, and preferably within a range of 95 ° to 120 ° (in FIG. 3). The case where the inclination angle of the wall surface 48e is 90 ° is illustrated).
If the inclination angle of the wall surface 48e is less than 90 °, an acute angle slope is formed due to processing variations, and it becomes practically impossible to process random irregularities on the second inclined surface 48d. If the angle exceeds 120 °, the existence ratio of the gentle slope increases, and the reflection characteristic deviates from the predetermined characteristic.
The reference plane S is a plane parallel to the surface of the substrate 10.
[0034]
Next, the pitch L of the reflective slope 48 is preferably a constant size within a range of 5 μm to 80 μm, and more preferably within a range of 10 μm to 60 μm. If the pitch L of the reflective inclined surface 48 is less than 5 μm, the pitch becomes very fine, the processing efficiency is deteriorated due to the formation of the first inclined surface 48c, and the height of the second inclined surface 48d is reduced. It becomes difficult to obtain the characteristics. On the other hand, if it exceeds 80 μm, the pitch becomes rough and it becomes difficult to control the reflection characteristics.
The pitch L of the reflective slope 48 is preferably in a relationship that does not cause moiré with the electrodes of the liquid crystal display device or the color filter pattern (R, G, B pattern or black mask pattern). . When the direction of the repetition period of the pitch L of the reflecting slope 48 is the same as the direction of the repetition period of the pattern of the electrode or the color filter, optical interference such as a moire pattern does not appear, but the electrode or the color filter If the pattern is uneven, or the direction of the repetition period of the pitch L of the reflective slope 48 is different from the direction of the repetition period of the electrode or color filter pattern, optical interference may occur. . In that case, the occurrence of optical interference can be suppressed and excellent visibility can be obtained by interposing a diffusion layer or a scattering layer between any layers between the surface of the reflector 47 and the substrate 20. it can.
[0035]
Further, the pitch of the first inclined surface 48c is set to L.₁And the pitch of the second inclined surface 48d is L₂L₁And L₂The ratio to L₁: L₂= 1: 1 to 1:10, preferably 1: 3.
The half width of the profile indicating the reflection characteristic of the reflected light is the pitch L of the first and second inclined surfaces 48c and 48d.₁, L₂It is determined in proportion to the size of. That is, L₁, L₂As the height increases, the area of the concavo-convex portion 12 increases, and the full width at half maximum increases accordingly.
[0036]
Therefore, L₁: L₂When 1: 1, the profile indicating the reflection characteristic of the reflector 47 is a curve indicated by the broken line (2) in FIG. 5, and the half-value widths of the reflection characteristic profiles corresponding to the inclined surfaces 48c and 48d are the same. Width, (30 ° -2θ₁) To (30 ° -2θ₂) In the angle range up to
L₁: L₂In the range from 1: 1 to 1: 3, the profile indicating the reflection characteristic of the reflector 47 is a curve indicated by the solid line (1) shown in FIG. 5 and has a reflection characteristic corresponding to the second inclined surface 48d. The half width of the profile is widened, and the reflectance is (30 ° -2θ₂). Thereby, the reflectance in the angle close | similar to an observer's eyes | visual_axis becomes high, and the brightness | luminance of reflected light can be improved.
[0037]
L₁: L₂Is out of the 1: 1 range₂Is L₁When it becomes smaller, the full width at half maximum of the profile of the reflection characteristic corresponding to the first inclined surface 48c becomes narrower, so that the reflectance becomes (30 ° −2θ₁), And the reflectance at an angle close to the observer's line of sight is lowered, which is not preferable.
L₁: L₂Is out of the 1: 3 range₂When the height increases, the half width of the reflection characteristic profile corresponding to the second inclined surface 48d becomes extremely wide, while the half width of the reflection characteristic profile corresponding to the first inclined surface 48c becomes extremely narrow and reflected. The rate also decreases, and as a result, the angle range with high reflectivity becomes narrow, which is not preferable.
[0038]
In the present embodiment, a particle layer 12a is formed by dispersing and adhering a large number of light-reflective microparticles 12b having different particle diameters on the surface of the reflective slope 48, and the irregular surface 12 is formed by the particle layer 12a. .
Examples of the light-reflective microparticles 12b include alumina particles, organic beads such as divinylbenzene polymers, SiO₂Spherical beads made of or the like are appropriately selected and used. The light-reflecting fine particles 12b have a radius in the range of 0.5 μm to 15 μm.
[0039]
When the reflector 47 is cut in a specific longitudinal section, the uneven surface 12 has a discontinuous inclination of the sectional curve of the longitudinal section as shown in FIG. 4, in other words, the first derivative of the sectional curve of the longitudinal section. The curve is discontinuous. A connecting portion (boundary portion) 12d between the minute convex portion 12c and the minute convex portion 12c does not have a curved surface.
Since the uneven surface 12 is composed of a particle layer 12a composed of a large number of light-reflective microparticles 12b having a radius within the above range, the depth D of the recess 12e is within a range of 0.3 μm to 3 μm. And irregularly distributed. Here, the depth D of the concave portion 12e means the reference plane S of the particle layer 12a including the top portion having the largest distance from the surface of the substrate 11 among the top portions of the convex portion 12c as shown in FIG.₂It is the distance from. When the depth D of the concave portion 12e exceeds 3 μm, when the transparent intervening layer 53 is formed on the particle layer 12a and flattened, the top of the convex portion 12c cannot be filled with the transparent intervening layer 53, and the desired flatness Cannot be obtained, causing display unevenness.
[0040]
Moreover, since this uneven surface 12 is comprised from the particle layer 12a which consists of many light-reflective microparticles 12b whose radius range is said range, the pitch P1 of the adjacent recessed part 12e is the range whose is 1 micrometer or more and 30 micrometers or less. It varies irregularly within.
In such a reflector 47, as shown in FIG. 1, the direction of the wall surface 48e is the observer's viewpoint Ob.₁In other words, the direction of the reflective slope 48 is the observer's viewpoint Ob.₁It is provided so that it may become the near side (opposite side to a Y direction).
According to the reflector 47 having such a configuration, when the reflected light of the light incident on the reflector 47 is observed from a specific viewing angle, it can be easily controlled to have a reflection characteristic that looks brighter than other viewing angles.
[0041]
In addition, the reflector 47 described above has a structure in which the slope of the cross-sectional curve of the vertical surface of the uneven surface 12 is discontinuous, but the present invention is not limited to this, and the slope of the cross-sectional curve of the uneven surface is continuous. In other words, the first derivative curve of the cross-sectional curve of the uneven surface may be continuously changed. However, when the slope of the cross-section curve is continuous, the half-value width of the Gaussian curve showing the reflection characteristics is narrower than that when the slope is discontinuous, so in order to obtain a high reflectivity over a wide angle range, It is preferable to employ one having a discontinuous inclination.
[0042]
In order to manufacture the reflector 47 as described above, a base material 11 having a plurality of reflective inclined surfaces 48 formed in a stripe shape in plan view is prepared on the surface, and a large number of random particles are formed on the surface of the reflective inclined surface 48. It can be obtained by dispersing and adhering the light-reflective fine particles 49 to form the particle layer 12a in which a large number of fine irregularities are randomly arranged on the surface.
In addition, as a method of manufacturing the base material 11 on which the plurality of reflective inclined surfaces 48 are formed, for example, a photosensitive resin liquid such as an acrylic resist is applied on the first substrate 10 by a spin coating method or the like. Thereafter, the photosensitive resin layer is formed by pre-baking, and the transfer mold having an uneven surface is pressed against the surface of the photosensitive resin layer and then released, and the transfer mold unevenness is formed on the surface of the photosensitive resin layer. It is obtained by forming a concavo-convex shape opposite to the surface and forming a plurality of reflective inclined surfaces 48 in a stripe shape in plan view. The uneven surface of the transfer mold has an uneven shape opposite to the unevenness of the surface of the substrate 11.
As another method for producing the base material 11, after applying a photosensitive resin liquid on the first substrate 10, it is photosensitive by a photolithography technique using multi-step exposure, development, and etching anisotropy. It can be obtained by forming a plurality of reflective inclined surfaces 48 in a planar view stripe shape on the surface of the resin layer.
[0043]
In the reflective liquid crystal display device 1 of the present embodiment, when external light is incident on the display surface 1a, the incident light Q enters the liquid crystal panel 35b, passes through each layer, reaches the surface of the reflector 47, and the reflector 47 The light is reflected at a wide angle by the uneven portion 12 and the reflective slope 48, and is again transmitted through the layers and emitted from the display surface 1a. Since the emitted light is scattered in a wide viewing angle range, the display surface 1a can be observed from a wide viewing angle without reflection of the light source.
[0044]
Further, the inclination angle θ of the second inclined surface 48d₂In the normal direction H of the display surface 1a₁And the observer's main viewing direction α₁By making (30 ° −θ) / 2 with respect to the angle θ formed by the above, the reflection angle of the reflected light can be adjusted to the observer's line of sight.₁And the main observation direction α₁The angle θ between₁A liquid crystal display device with a bright display (screen) can be realized at 0 to 20 degrees.
For this reason, when the liquid crystal display device of this embodiment is incorporated in a display unit of a portable electronic device such as a mobile phone or a notebook PC, the visibility is particularly good.
In the first embodiment, the case where a large number of light-reflective microparticles 49 having different particle diameters are dispersed and bonded to the surface of the wall surface 48e has been described. However, the light-reflective microparticles 49 are attached to the wall surface 48e. You don't have to.
[0045]
(Second Embodiment)
Next, a reflective liquid crystal display device according to a second embodiment of the present invention will be described.
The reflective liquid crystal display device of the second embodiment is different from the first reflective liquid crystal display device 1 shown in FIGS. 1 to 4 in that the configuration of the reflector provided in the liquid crystal cell 35b is different. is there.
FIG. 6 is an enlarged cross-sectional view showing a part of a reflector 147 provided in the reflective liquid crystal display device according to the second embodiment.
[0046]
The reflector 147 includes a base material 111 and a high reflection film 112a formed on the base material 111. The surface of the high reflection film 112a is an uneven surface 112. The difference between the substrate 111 and the substrate 11 provided in the reflector 47 of the first embodiment is that a large number of minute irregularities are randomly formed on the surface of the substrate 111, and the minute irregularities of the substrate 111 are The uneven surface 112 is reflected by the shape of the highly reflective film 112a thereon.
[0047]
The base material 111 is made of a photosensitive resin such as an acrylic resist in the same manner as the base material 11 described above. The base material 111 is continuously provided with a reflective slope 148 in a stripe shape in plan view as shown in FIG. A plurality of them are formed.
Further, as shown in FIG. 6, each of the reflecting slopes 148... Has a first inclined surface 148 c located on the base end 148 a side of each reflecting slope 148 and an upper end 148 b side of each reflecting slope 148. A second inclined surface 148d having a larger inclination angle than the first inclined surface 148c is provided in contact with the inclined surface 148c.
Further, a wall surface 148e is provided between two adjacent reflecting slopes 148 and 148, and the reflecting slopes 148 are connected by the wall surfaces 148e.
As shown in FIG. 6, the first and second inclined surfaces 148c and 148d are inclined in the same direction along the width direction of the stripe (the horizontal direction in FIG. 6).
[0048]
In addition, the inclination angle θ of the first and second inclined surfaces 148c and 148d₁, Θ₂, Pitch L of the reflective slope 148, pitch L of the first slope 148c₁And the pitch L of the second inclined surface 148d₂Ratio L₁: L₂Is the same as in the case of the first embodiment.
[0049]
Moreover, the convex part 111a and the recessed part 111b are irregularly arrange | positioned and formed in the surface of each reflective slope 148 .... The recess 111b has a depth in the range of 0.3 μm or more and 3 μm or less, and the depth of the recess 111b here includes the top of the top of the protrusion 111a that has the largest distance from the surface of the substrate 111. The distance from the surface.
Moreover, as for this base material 111, the adjacent recessed part 111b varies irregularly with the pitch within the range of 1 micrometer or more and 30 micrometers or less. When the pitch of the adjacent recesses 111b is less than 1 μm, there is a restriction on the production of the transfer mold used to form the base material 111, and the processing time is extremely long, and a shape capable of obtaining desired reflection characteristics is formed. Inability to generate interference light occurs.
[0050]
In the present embodiment, a high reflection film 112a having a film thickness described later is formed on the surface of the substrate 111 on which a large number of minute irregularities are randomly formed on the surface. The surface of the high reflection film 112a is formed as an uneven surface 112 by reflecting the minute uneven shape of the surface of the substrate 111 on the high reflection film 112a.
When the reflector 147 is cut longitudinally at a specific longitudinal section of a large number of reflecting slopes 148 formed on the substrate 111, the uneven surface 112 which is the surface of the highly reflective film 112a has a sectional curve of the longitudinal section as shown in FIG. In other words, the first derivative of the longitudinal section curve is discontinuous.
[0051]
As the metal material constituting the highly reflective film 112a, a metal having a high reflectance such as Al or Ag is used.
The thickness of the highly reflective film 112a is preferably in the range of 80 nm to 200 nm. If the film thickness is less than 80 nm, the reflectivity of light by the high reflection film 112a is too low and the display in the reflection mode becomes dark, which is not preferable. If the film thickness exceeds 200 nm, the film formation cost increases significantly. Since the unevenness of the uneven surface 112 becomes small and becomes almost flat, it is not preferable.
[0052]
The highly reflective film 112a irregularly varies within a range of 0.3 μm to 3 μm in depth D of the recess 112b for the same reason as in the first embodiment.
Further, the pitch P of the adjacent concave portions 112b varies irregularly within a range of 1 μm or more and 30 μm or less.
[0053]
According to the reflector 147 having such a configuration, an effect similar to that of the reflector 47 of the first embodiment can be obtained.
[0054]
In order to manufacture the reflector 147 as described above, a base having the same shape as the base 111 (except for the base 11 used in the first embodiment), except that the surface of the reflective slope 148 is not formed with minute irregularities. A substrate having the same shape) is prepared, and a microparticle kneaded liquid in which a large number of microparticles having a random particle size are dispersed and kneaded in a crystalline polymer is applied to the surface of the substrate and cured to form a micro uneven shape on the surface. A fine particle kneaded layer is formed to form a matrix.
As the crystalline polymer, a liquid crystalline polymer is used. The fine particles are appropriately selected from materials having a refractive index different from that of the polymer. For example, organic beads such as alumina and divinylbenzene polymer, silica, and the like are appropriately selected and used. The fine particles having a radius of 0.5 μm or more and 15 μm or less are used. The microparticles dispersed in the crystalline polymer as described above are unlikely to cause secondary aggregation, and the surface of the microparticles protrudes from the surface. Since the surface of the particle kneading layer also protrudes from the surface of the fine particle, it has a fine uneven shape. On the other hand, when an amorphous polymer is used, the surface energy becomes high, so that the fine particles do not protrude on the surface, and the fine uneven shape is not formed on the surface of the fine particle kneaded layer.
[0055]
Next, after forming a metal such as Ni by the electroforming process to a necessary thickness on the surface of the master particle on the fine particle kneading layer side, and releasing the mold, An electroforming mold having a mold surface having a micro uneven shape in which the micro uneven shape and the uneven surface are reversed is obtained.
[0056]
Next, a photosensitive resin solution such as an acrylic resist is applied on the first substrate 10 by spin coating or the like, and then pre-baked to form a photosensitive resin layer. After pressing against the surface of the resin layer, the mold is released, and when the surface of the photosensitive resin layer is formed with a micro uneven shape opposite to the micro uneven shape of the mold surface of the electroforming mold, a large number of micro uneven surfaces are formed on the surface. The base material 111 formed at random is obtained.
Next, when a highly reflective film having the above-mentioned thickness range is formed on the surface of the substrate 111 by a film forming method such as sputtering or vacuum evaporation of a metal material such as Al, the highly reflective film also has a large number of minute irregularities on the surface. Have a shape randomly arranged, and the reflective layer 112 is obtained. In this way, the target reflector 147 is obtained.
[0057]
In the reflective liquid crystal display device of the present embodiment, the same effect as that of the reflective liquid crystal display device of the first embodiment can be obtained by including the reflector 147 having the above configuration.
[0058]
In the first and second embodiments, the case where the reflector 47 or the reflector 147 that reflects light incident from the outside is incorporated between the substrate 10 and the substrate 20 has been described. A reflector externally attached type in which a reflector is provided outside the substrate 10 can also be used.
In the first and second embodiments, the case where the liquid crystal display device of the present invention is applied to a reflective liquid crystal display device has been described. However, the present invention can also be applied to a transflective liquid crystal display device. After the highly reflective film 112a of the reflector 47 or the reflector 147 is formed with a film thickness of 80 to 200 nm, a fine opening is formed in the pixel by a known method such as photolithography as viewed in a plan view. In this case, the area ratio of the opening may be 15 to 30% with respect to one pixel pitch area, and the backlight may be provided on the outer surface side of the first substrate 10. The highly reflective film may be a semi-transmissive type by making it a thin film semi-transmissive of 80 nm or less.
[0059]
In the first and second embodiments, the case where the present invention is applied to a simple matrix type reflective liquid crystal display device has been described. However, an active matrix type or segment type liquid crystal display using thin film transistors or thin film diodes has been described. The same applies to devices. All of these liquid crystal display devices are included in the present invention.
In the first to second embodiments, the case where one retardation plate is provided between the second substrate 20 and the polarizing plate 28 has been described. However, a plurality of retardation plates are provided. Also good.
[0060]
【The invention's effect】
As described above in detail, according to the reflector of the present invention, the reflective inclined surface is constituted by the first inclined surface and the second inclined surface having an inclination angle larger than that of the first inclined surface. Since the irregular surface is formed on the surface, the reflected light can be scattered to increase the luminance in a wide angle range, and the reflection angle of the reflected light can be arbitrarily controlled.
[0061]
Further, according to the reflective liquid crystal display device of the present invention, since the above reflector is provided, the brightness of the reflected light is high in a wide angle range, and the reflected angle of the reflected light is close to the observer's line of sight. A close reflection characteristic can be exhibited, and a wide viewing angle characteristic can be realized.
[0062]
Furthermore, according to the reflector manufacturing method of the present invention, the reflector of the present invention having the above-described configuration can be easily manufactured.
[Brief description of the drawings]
FIG. 1 is a diagram showing a partial cross-sectional structure of a reflective liquid crystal display device according to a first embodiment of the present invention.
FIG. 2 is a perspective view schematically showing a reflector according to the first embodiment of the present invention.
FIG. 3 is an enlarged cross-sectional view corresponding to the line AA in FIG. 2;
FIG. 4 is an enlarged cross-sectional view showing a cross-sectional curve of a cross section of the concavo-convex surface of the reflector according to the first embodiment.
FIG. 5 is a graph showing the relationship between the reflection angle and the reflectance of the liquid crystal display device of the first embodiment.
FIG. 6 is an enlarged sectional view showing a part of a reflector according to a second embodiment of the present invention.
FIG. 7 is an enlarged cross-sectional view showing a cross-sectional curve of a cross-section of a concavo-convex surface of a reflector according to a second embodiment.
FIG. 8 is a side cross-sectional view showing an example of a conventional reflective liquid crystal display device.
FIG. 9 is a view showing a reflection characteristic of a reflector provided in a conventional reflective liquid crystal display device.
FIG. 10 is an explanatory diagram of a usage state of a liquid crystal display device provided in a mobile phone.
[Explanation of symbols]
1a Display surface
10 One board
11, 111 Base material (substrate)
12, 112 Uneven surface
12b Light-reflective microparticle
12c, 111a Convex part
12e, 111b recess
15 Transparent electrode layer (electrode)
16 Alignment film
20 The other board
25 Transparent electrode layer (electrode)
26 Alignment film
30 Liquid crystal layer
35b liquid crystal cell
47, 147 reflector
48, 148 Reflective slope
48a, 148a Base end of reflection slope
48b, 148b Upper end of reflective slope
48c, 148c first inclined surface
48d, 148d second inclined surface
θ₁  Inclination angle of the first inclined surface
θ₂  The angle of inclination of the second inclined surface
S₁  Board surface
L Reflective pitch
L₁ The pitch of the first inclined surface
L₂Second inclined surface pitch

Claims (4)

A reflector that reflects incident light, wherein a plurality of stripe-like reflective slopes in a plan view are continuously formed on the surface of the substrate,
Each reflective slope has a first inclined surface located on the base end side of each reflective slope, and is located on the upper end side of each reflective slope and is in contact with the first slope and more inclined than the first slope. A second inclined surface having a large corner is provided, and the reflective inclined surface is an irregular uneven surface,
The concavo-convex surface is irregularly formed within a range where the height of the convex portion or the depth of the concave portion on the reflective slope is 0.3 μm or more and 3 μm or less, and the adjacent convex portions or the adjacent concave portions. The pitch between them is irregularly arranged within a range of 1 μm or more and 30 μm or less,
The inclination angle theta ₁ of the first inclined surface is a constant size in the range of 20 ° 5 ° or more relative to the substrate surface, the inclination angle theta ₂ of the second inclined surface is 5 ° relative to the substrate surface The pitch L of the reflecting slope is set to a constant size within a range of 5 μm to 80 μm, the pitch of the first inclined surface is L _1, and the second slope is set to a constant size within a range of 45 ° or less. when the pitch of the inclined surface and the _{L 2, L 1} and _{L 2} ratio of the _{L 1: L 2 = 1:} 1~1: 10 by weight, the inclination angle of the first inclined surface theta ₁ and the second The relationship with the inclination angle θ ₂ of the inclined surface is 5 ° ≦ (θ ₂ −θ ₁ ) ≦ 15 °, and the first and second inclined surfaces are inclined in the same direction along the width direction of the stripe. reflector, characterized by that. The profile showing the reflection characteristics of the first and second inclined surfaces shows a Gaussian distribution shape centered on the regular reflection angle of incident light, and the profile showing the reflection characteristics of the reflector is the first and second inclinations. The reflector according to claim 1, wherein the shape of each skirt of each profile of the surface is overlapped.   The uneven surface is formed by dispersing fine particles, forming an electroforming mold on the surface of the fine particle kneading layer having a fine uneven surface, and pressing the mold surface of the electroforming mold against the surface of the substrate. The reflector according to claim 1, wherein the reflector is formed by releasing a mold. An electrode and an alignment film are provided in order from the one substrate side on the inner surface side of one of the substrates facing each other across the liquid crystal layer, and an electrode and an alignment film are provided in this order from the other substrate side on the inner surface side of the other substrate The reflector according to any one of claims 1 to 3 is provided between the electrode provided on the outer surface side of the one substrate of the liquid crystal cell or the one substrate and the inner surface side thereof. A reflective liquid crystal display device.

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