JP3748761B2 - Reflector and reflective liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reflector that can be suitably used for a reflective liquid crystal display device using external light as a light source, and a reflective liquid crystal display device using the same. More specifically, a reflector that has good reflectivity over a wide range of angles and can increase the reflectivity particularly in a desired range of reflection direction, and a wide viewing angle by using the reflector, The present invention relates to a reflective liquid crystal display device having appropriate directivity so that sufficient brightness can be secured in a normal visual field range of a display device incorporated in a specific device such as a notebook personal computer.
[0002]
[Prior art]
In recent years, a reflective liquid crystal display device using external light as a light source has been widely used as a display unit of a handheld type computer or the like because of particularly low power consumption. This reflection type liquid crystal display device reflects light incident from the display surface side to the display surface side by an internal reflector so that the user can see the display shown according to the molecular arrangement state of the liquid crystal layer. It is to make.
[0003]
When a reflector having a flat mirror surface is used as a reflector used in this type of reflective liquid crystal display device, it exhibits a very high reflectance at a specific reflection angle corresponding to the incident angle. The range of the reflection angle with a high rate is very narrow, that is, the viewing angle is narrow. For this reason, attempts have been made to obtain good reflectivity in a wide range of directions by forming a large number of concave portions and grooves forming a part of a spherical surface on the reflector surface, or providing random irregularities. (Japanese Patent Application Nos. 9-203637, 9-197576, 9-194463, etc.).
[0004]
Of these, a reflector as shown in FIG. 8 is proposed in Japanese Patent Application No. 9-203637, in which many concave portions forming a part of a spherical surface are provided on the reflector surface. The reflector 51 of the form shown in this figure has an inner surface on the surface of a flat resin base 53 (base for reflector) made of a photosensitive resin layer or the like provided on a substrate 52 made of glass or the like. Is formed continuously so that a large number of concave portions 54 forming a part of a spherical surface overlap with each other, and a reflective film 55 made of a thin film such as aluminum or silver is formed thereon by vapor deposition or printing.
[0005]
The recesses 54 are randomly formed in a depth range of 0.1 to 3 μm, and the pitches of the adjacent recesses 54 are also randomly arranged in a range of 5 to 50 μm. The inner surfaces of the recesses 54 are each a curved surface forming a part of a single spherical surface, and the inclination angle is set in a range of −18 to +18 degrees.
[0006]
Note that the “depth of the recess” is the distance from the reflector surface to the bottom of the recess, and the “pitch of the adjacent recess” is the distance between the centers of the recesses that are circular when viewed in plan. . In addition, as shown in FIG. 9, the “inclination angle of the inner surface of the concave portion” means a horizontal plane of the inclined surface within a minute range when a small range of 0.5 μm width is taken at an arbitrary position on the inner surface of the concave portion 54. The angle θ with respect to. The positive / negative of the angle θ is defined, for example, such that the right slope in FIG. 8 is positive and the left slope is negative with respect to the normal line standing on the reflector surface.
[0007]
The reflector 51 has reflection characteristics as indicated by β in FIG. FIG. 5 is a graph showing a reflection characteristic curve in which the vertical axis represents the reflectance (reflection intensity) and the horizontal axis represents the reflection angle at an incident angle of 30 degrees. As shown in FIG. 10, the incident angle is an angle ω formed by the normal H standing on the surface of the reflector 51 and the incident light J.₀It is. The reflection angle is an angle ω formed by the normal H and the reflected light K on a plane including the normal H and the incident light J. As indicated by β in FIG. 5, the reflector 51 has a good reflectivity to some extent within a range of 15 ° ≦ ω ≦ 45 ° with a reflection angle of 30 degrees as the center.
[0008]
[Problems to be solved by the invention]
The above-described conventional reflector 51 can obtain a somewhat good reflectivity over a relatively wide range of angles due to the presence of the recesses. However, as shown by β in FIG. 5, there are regions having a relatively high reflection intensity symmetrically about the reflection angle of 30 degrees with the reflection angles of 15 degrees and 45 degrees as the left and right peaks.
[0009]
However, as shown in FIG. 11, a display device incorporated in a device that is used with an inclined display surface, such as a notebook personal computer, varies depending on the degree of inclination of the display surface and the position of the light source. It is often seen from the direction near the normal to the display surface. FIG. 11 is a diagram for explaining a state in which a notebook computer having a main body 61 and a lid 62 is used. The display device 63 is provided on the inner surface of the lid 61. In FIG. 11, P is a normal to the display device 63, Q is incident light, ω₀Is an incident angle (for example, 30 degrees). R₁Is the reflection angle ω₀And the reflected light with the same incident angle ω, R₂Is the reflection angle ω₀Is reflected light with an angle of incidence smaller than ω, R_ThreeIs the reflection angle ω₀Is reflected light larger than the incident angle ω.
[0010]
As can be understood from the figure, the user's line of sight is reflected light R close to the normal normal P.₂Concentrate in the direction of. In contrast, the reflected light R_ThreeIs a direction in which the display device 63 is looked up from below and is difficult to see. Therefore, considering the convenience of use by the user, it is desired to ensure a wide viewing angle and at the same time to increase the reflectivity in the direction where the reflection angle is small.
[0011]
On the other hand, when viewing a display device on a horizontal plane, such as a table-type game machine, as shown in FIG. 12, it is often viewed from a direction generally parallel to the display surface. . FIG. 12 is a diagram for explaining a use state of the display device 73 provided horizontally on the table 72. In FIG. 12, W is a normal to the display device 73, S is incident light, ω₀Is an incident angle (for example, 30 degrees). T₁Is the reflection angle ω₀And reflected light having the same incident angle ω, T₂Is the reflection angle ω₀Is reflected light whose T is smaller than the incident angle ω, T_ThreeIs the reflection angle ω₀Is reflected light larger than the incident angle ω.
[0012]
As can be seen from the figure, the user's line of sight is usually reflected light T.₁Reflected light T having a larger reflection angle than_ThreeConcentrate in the direction of. In contrast, the reflected light T₂Is a direction that looks into the display device 73 from above and is difficult to see. Therefore, considering the convenience of use by the user, it is desirable to ensure a wide viewing angle and at the same time to increase the reflectivity in the direction where the reflection angle is large.
[0013]
The present invention has been made to solve the above-described problem, and has a good reflectance over a wide range of angles, and a reflection angle (including a negative value) smaller than the incident angle, a large reflection angle, and the like. Specific use such as a reflector that can increase the reflectivity in a desired direction, and a reflector that has a wide viewing angle and has a display surface inclined or horizontal. It is an object of the present invention to provide a reflective liquid crystal display device having appropriate directivity with respect to a normal visual field range in a situation.
[0014]
[Means for Solving the Problems]
  In order to solve the above-mentioned problems, the present invention has a large number of recesses formed on the reflector surface, and the inner surface of the recess is surrounded by a peripheral curved surface and a peripheral curved surface, which are part of two spherical surfaces each having a different radius. Consists of a continuous surface with a bottom curved surface at a certain position,And the inner surface of the recess is composed of two spherical surfaces each having a different radius, one is a peripheral curved surface, and the other is a bottom curved surface,The spherical surface that forms the peripheral curved surfaceCurvature in cross sectionThe radius of the spherical surface forming the bottomCurvature in cross sectionProvided is a reflector having a smaller radius and normals standing on the reflector surface from the center of each spherical surface on different straight lines.
  In the present invention, a plurality of concave portions are formed on the reflector surface, and the inner surface of the concave portion includes a main first curved surface portion and a second curved surface portion formed in the first curved surface portion, and the second curved surface. And a center of curvature of the first curved surface portion is different from that of the first curved surface portion, and a maximum luminance direction of reflected light of outside light is set according to a position of the second curved surface portion. I will provide a.
[0015]
  According to this reflector, the spherical surface forming the peripheral curved surface (first curved surface portion)curvatureSince the radius is small and a wide range of tilt angles can be obtained, a sufficiently wide viewing angle can be obtained. In addition, the bottom curved surface (second curved surface portion) present at a position slightly deviated from the center of the concave portionLarge radius of curvatureSince the curve is close to a flat surface, the distribution of the specific inclination angle is high on the inner surface of the recess, and as a result, the reflectance at the reflection angle in the direction larger or smaller than the incident angle is the highest, Reflectivity also increases.
[0016]
  in this case,The present inventionAs described above, it is desirable that the normals standing on the reflector surface from the center of each spherical surface are separated with an interval in the range of 0.1 to 10 μm. This is because when the thickness is smaller than 0.1 μm, appropriate directivity cannot be obtained, and when it is larger than 10 μm, the reflection intensity of regular reflection is remarkably reduced. Note that the greater the distance from each normal, the greater the difference between the incident angle and the reflection angle at which the reflectance is highest.
[0017]
  The inclination angle of the inner surface of each recess isThe present inventionAs described above, it is desirable that the peripheral curved surface is in the range of 10 to 35 degrees and −35 to −10 degrees, and the bottom curved surface is in the range of 4 to 17 degrees and −17 to −4 degrees. This is because when the inclination angle of the peripheral curved surface exceeds the range of 10 to 35 degrees and −35 to −10 degrees, the inclination angle of the reflected light is excessively widened and the reflection intensity is lowered, and the inclination angle of the bottom curved surface is 4 to 17 degrees. And if it exceeds the range of -17 to -4 degrees, the reflectance in a specific direction is not sufficiently high.
[0018]
  The depth of each recess isThe present inventionAs described above, it is desirable to form randomly within a range of 0.1 to 3 μm. If the thickness is smaller than 0.1 μm, the specular reflection becomes too strong. This is because it cannot be obtained. Further, if the depth is not random, but only the recesses of a certain depth are used, there is a problem in that regularity occurs and the interference color of light comes out and the reflected light is colored.
[0019]
As described above, the “depth of the recess” is a distance from the reflector surface to the bottom of the recess. In addition, the “inclination angle of the inner surface of the concave portion” means, as described with reference to FIG. 9, when a small range of 0.5 μm width is taken at an arbitrary position on the inner surface of the concave portion, The angle θ with respect to the horizontal plane. The positive / negative of the angle θ is defined, for example, such that the right slope in FIG. 8 is positive and the left slope is negative with respect to the normal line standing on the reflector surface.
[0020]
  About the arrangement of each recess, they may be separated from each other,The present inventionIt is desirable to form them continuously as described above. Thereby, since a recessed part can be efficiently arrange | positioned in the reflector surface whole surface, the effect of extending a viewing angle can be exhibited to the maximum, maintaining moderate directivity by a recessed part.
[0021]
  In addition, as other arrangementsThe present inventionAs described above, a large number of recesses can be formed on the reflector surface together with a large number of grooves. Thereby, in addition to the above-described effect due to the recess, the groove can have the effect of widening the viewing angle in the direction perpendicular to the groove. In this case, the grooves may be straight or curved, and may intersect with each other at an arbitrary angle. In addition, the recess and the groove are formed at a density within a range where the mutual effect is not lost.
[0022]
  Also,BookAs an invention,AheadA reflective liquid crystal display device comprising the reflector according to any one of the above. In addition, as an installation form of the reflector, any of an external type installed outside the liquid crystal cell or a built-in type installed on the inner surface of the substrate constituting the liquid crystal cell may be used.
[0023]
The reflective liquid crystal display device has a wide viewing angle and appropriate directivity. Therefore, when incorporated in a specific device such as a notebook personal computer, sufficient brightness can be secured over the normal visual field range of the user.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a reflector according to the present embodiment. As shown in this figure, the reflector 1 of the present embodiment is a flat resin base material 3 (reflector base material) made of a photosensitive resin layer or the like provided on a substrate 2 made of glass or the like, for example. 2 is formed continuously so that a large number of concave portions 4 having a specific shape shown in FIG. 2 overlap each other, and a reflective film 5 made of a thin film such as aluminum or silver is formed thereon by vapor deposition or printing. It is formed.
[0025]
  2A is a cross-sectional view of the recess 4, and FIG. 2B is a plan view. As shown in this figure, the inner surface of each recess 4 is formed by a peripheral curved surface (first curved surface portion) 4a and a bottom curved surface (second curved surface portion) 4b located at a position surrounded by the peripheral curved surface 4a. . The peripheral curved surface 4a is centered O₁AscurvatureRadius is R₁Is a part of a spherical surface. The bottom curved surface 4b has a center at O.₂AscurvatureRadius is R₂Is a part of a spherical surface. O which is the center of each spherical surface₁And O₂From the above, the normals standing on the surface of the reflector 1 are respectively separated by straight lines L₁, L₂Located on the top.
[0026]
  EachcurvatureRadius R₁And R₂And R₁<R₂And 10 μm ≦ R₁≦ 70μm, 20μm ≦ R₂It changes within a range of ≦ 100 μm. In FIG. 2A, θ₁Is the inclination angle of the peripheral curved surface 4a, and 10 ° ≦ θ₁≦ 35 ° and -35 ° ≦ θ₁It changes within a range of ≦ −10 °. And θ₂Is the inclination angle of the bottom curved surface 4b, 4 ° ≦ θ₂≦ 17 ° and -17 ° ≦ θ₂It changes within a range of ≦ −4 °.
[0027]
  The radius r of the peripheral curved surface 4a viewed from the plane direction₁And the radius r of the bottom curved surface 4b₂For eachcurvatureRadius, R₁, R₂And tilt angle θ₁, Θ₂It is decided according to.
[0028]
The depth d of the recess 4 takes a random value for each recess in the range of 0.1 to 3 μm. If the depth of the concave portion 4 exceeds 3 μm, when the concave portion 4 is flattened in a subsequent process, the top of the convex portion cannot be filled with the flattening film, and the desired flatness cannot be obtained, and is less than 0.1 μm. This is because regular reflection becomes too strong.
[0029]
Returning to FIG. 1 again, the arrangement of the recesses 4 and the like will be described. The pitch of the adjacent recesses 4 is randomly arranged in the range of 5 to 50 μm. This is because, if the pitch between the adjacent recesses 4 is regular, there is a problem in that the interference color of light comes out and the reflected light is colored. Further, when the pitch of the adjacent recesses 4 is less than 5 μm, there are restrictions on the fabrication of the reflector forming matrix, the processing time becomes extremely long, and a shape sufficient to obtain the desired reflection characteristics cannot be formed, interference This is because problems such as generation of light occur. Further, from the practical point of view when using a diamond indenter that can be used for manufacturing a reflector forming matrix, it is desirable that the pitch of the adjacent recesses 4 be 5 to 50 μm.
[0030]
Although there is no limitation in particular in the manufacturing method of the reflector of the said structure, For example, it can manufacture as follows. First, as shown in FIG. 3A, a flat matrix base 7 made of, for example, brass, stainless steel, tool steel or the like is fixed on a table of a rolling device. Then, the surface of the matrix base material 7 is pressed with a diamond indenter 8 having a specific shape corresponding to the recess 4 shown in FIG. 2, and the diamond indenter 8 is moved up and down by moving the matrix base material 7 in the horizontal direction. By repeating the pressing operation many times, a large number of recesses 7a having different depths and arrangement pitches are rolled on the surface of the matrix substrate 7, and the reflector forming mother as shown in FIG. Let it be type 9.
[0031]
As shown in FIG. 4, the rolling device used here is such that the table for fixing the matrix substrate 7 moves in the X and Y directions in the horizontal plane with a resolution of 0.1 μm, and the diamond indenter 8 has a resolution of 1 μm. It has a function of moving in the vertical direction (Z direction). The pitch of adjacent recesses can be changed by changing the movement distance in the X direction and the Y direction, and the depth of each recess can be changed by changing the movement distance in the Z direction. The tip of the diamond indenter 8 has a diameter R₂Is formed by deviating from the central axis, and slightly above the diameter R₁The part of is formed.
[0032]
Thereafter, as shown in FIG. 3 (c), the mother die 9 is housed and arranged in a box-shaped container 10, and a resin material 11 such as silicone is poured into the container 10 and allowed to stand and cure at room temperature. The removed resin product is taken out from the container 10 and an unnecessary portion is cut out. As shown in FIG. 3 (d), the resin product has a number of convex portions which are concave and convex shapes opposite to the number of concave portions forming the mold surface. A transfer mold 12 having a mold surface 12a is created.
[0033]
Next, a photosensitive resin liquid such as an acrylic resist, a polystyrene resist, an azide rubber resist, and an imide resist is applied to the upper surface of the glass substrate by a coating method such as spin coating, screen printing, or spraying. Then, after the coating is finished, the photosensitive resin liquid on the substrate is prebaked at a temperature range of, for example, 80 to 100 ° C. for 1 minute or more using a heating apparatus such as a heating furnace or a hot plate, and the resin base material is formed on the substrate. A photosensitive resin layer 3 is formed. However, since the pre-baking conditions differ depending on the type of photosensitive resin used, it goes without saying that the treatment may be performed at a temperature and time outside the above range. In addition, it is preferable that the film thickness of the photosensitive resin layer formed here shall be the range of 2-5 micrometers.
[0034]
Thereafter, as shown in FIG. 2 (e), after using the transfer mold 12 shown in FIG. 2 (d) and pressing the mold surface 12a of the transfer mold 12 against the resin base material 3 on the glass substrate for a predetermined time, The transfer mold 12 is removed from the resin base material 3. In this way, as shown in FIG. 2 (f), the convex portions of the transfer mold surface 12 a are transferred to the surface of the resin substrate 3 to form a large number of concave portions 4. Further, it is preferable to select a value suitable for the type of the resin base material 3 to be used as the pressing pressure at the time of pressing, for example, 30 to 50 kg / cm.²The pressure should be about a certain level. It is preferable to select a value suitable for the type of the resin base material 3 used for the pressing time, for example, a time of about 30 seconds to 10 minutes.
[0035]
Thereafter, light such as ultraviolet rays for curing the resin base material 3 is irradiated from the back side of the transparent glass substrate to cure the resin base material 3. In the case of the resin base material 3 composed of the above-mentioned type of photosensitive resin layer, the light beam such as ultraviolet rays irradiated here is 50 mJ / cm.²The above strength is sufficient to cure the resin base material 3, but it is needless to say that irradiation may be performed with other strength depending on the type of the photosensitive resin layer. And the post-baking which heats the resin base material 3 on a glass substrate at about 240 degreeC for 1 minute or more using the same heating furnace as a prebaking, a heating apparatus, such as a hot plate, is performed on a glass substrate. The resin base material 3 is baked.
[0036]
Finally, for example, aluminum is formed on the surface of the resin substrate 3 by electron beam evaporation or the like, and the reflective film 1 is formed along the surface of the recess, whereby the reflector 1 of the present embodiment is completed.
[0037]
  In FIG. 5, α represents the reflectance (reflection intensity) on the vertical axis and the reflection angle on the horizontal axis at an incident angle of 30 degrees (incident from the right direction in FIG. 2) for the reflector 1 of the present embodiment. It is a graph which shows a reflection characteristic curve. As described above, in the reflector 1 of the present embodiment, the peripheral curved surface formed of a part of a spherical surface having a small radius on the inner surface of the recess 4.(First curved surface part)4a exists and gives a range of inclination angles having a relatively large absolute value, and therefore has a good reflectance in a wide range of 15 ° ≦ ω ≦ 45 °. Also, a bottom curved surface consisting of a part of a spherical surface with a large radius(Second curved surface part)Since the curved surface close to 4b, that is, a flat surface is unevenly distributed, the ratio of the inner surface that gives a specific range of inclination angles increases. As a result, the reflectivity at a small reflection angle is the highest than the incident angle of 30 degrees and the reflection angle of 30 degrees in the target direction.ThatThe reflectance in the vicinity is also high. Compared with the reflector 51 according to the prior art, the reflectance at a reflection angle of 20 degrees is higher by 10% or more.That is, the maximum brightness direction of the reflected light of the external light is set according to the position of the bottom curved surface (second curved surface portion).
[0038]
Although not shown, when the light is incident from the left side of FIG. 2, the reflectance at the large reflection angle is the highest and higher than the incident angle of 30 degrees and the reflection angle of 30 degrees in the target direction. As a peak, the reflectance in the vicinity also increases.
[0039]
In addition, when the light quantity of the whole reflected light of the reflector of this invention and the reflector of a prior art is compared, there is no significant difference in both. When the reflection characteristics α and β in FIG. 5 are compared, it appears that α has a larger amount of light as a whole, but this is because it is difficult to strictly align the conditions in the comparison experiment.
[0040]
Further, according to the above manufacturing method, when manufacturing the mother die 9 for forming the reflector, the diamond indenter 8 is simply moved up and down to press the surface of the mother die substrate 7, so that the diamond indenter is used. 8 and the matrix substrate 7 do not rub against each other. As a result, the surface state of the tip of the diamond indenter 8 is reliably transferred to the side of the mother die 9, and if the tip of the indenter 8 is in a mirror surface state, the inner surface of the concave portion of the mother die 9 and the inner surface of the concave portion of the reflector can easily be brought into the mirror state can do.
[0041]
Furthermore, compared to the method of forming a concavo-convex surface by heating a resin film such as polyester, the depth, diameter, pitch and other dimensions of the recess, the surface state of the recess inner surface, etc. are all controlled, By using a high-precision rolling device, the concave shape of the reflector can be created almost as designed. Therefore, according to this method, the reflection characteristics such as the reflection angle and reflection efficiency of the reflector to be created can be easily controlled, and a desired reflector can be obtained.
[0042]
In addition, as a manufacturing method, the rolling pattern of the recesses shown in FIG. 3 is only an example, and it is needless to say that the design can be changed as appropriate. Further, various materials such as a reflector base material and a base material for a matrix, and a transfer type constituent material can be appropriately changed.
[0043]
FIG. 6 is a diagram showing a reflector according to another embodiment of the present invention. As shown in this figure, the reflector 31 of the present embodiment is a flat resin substrate 33 (substrate for reflector) made of a photosensitive resin layer or the like provided on a substrate 32 made of glass or the like, for example. A stripe groove 34 is formed on the surface, and then, a large number of concave portions 35 having a specific shape are randomly formed, and a reflective film 36 made of a thin film such as aluminum or silver is formed thereon by vapor deposition or printing. It is a thing.
[0044]
Here, the concave portion 35 is the same as the concave portion 4 shown in FIG. 2, and the inner surface thereof is formed by a peripheral curved surface that is a part of a spherical surface and a bottom curved surface at a position surrounded by the peripheral curved surface. ing. Various conditions such as the relationship between the radius of the peripheral curved surface and the radius of the bottom curved surface, and the point where the normal line standing on the surface of the reflector 31 from the center of each spherical surface is located on the same straight line are also described for the concave portion 4. It is the same as that.
[0045]
According to the present embodiment, in addition to the above effect that the viewing angle of the recess can be widened and appropriate directivity can be provided, the groove can also have the effect of widening the viewing angle in the direction perpendicular to the groove. it can.
[0046]
Next, an STN (Super Twisted Nematic) type reflective liquid crystal display device having the above reflector will be described.
As shown in FIG. 7, this reflective liquid crystal display device is provided with a liquid crystal layer 15 between a pair of display side glass substrate 13 and a back side glass substrate 14 having a thickness of 0.7 mm, for example. One retardation plate 16 made of polycarbonate resin, polyarylate resin, or the like is provided on the upper surface side of the first retardation plate 16, and a first polarizing plate 17 is disposed on the upper surface side of the retardation plate 16. Further, the second polarizing plate 18 and the reflector 1 of the present embodiment shown in FIG. 1 are sequentially provided on the lower surface side of the rear glass substrate 14.
[0047]
The reflector 1 is attached so that the surface on which the concave portion 4 is formed is opposed to the lower surface side of the second polarizing plate 18, and light such as glycerin is interposed between the second polarizing plate 18 and the reflector 1. An adhesive 19 made of a material that does not adversely affect the refractive index is filled.
Transparent electrode layers 20 and 21 made of ITO (Indium Tin Oxide) or the like are respectively formed on the opposing surface sides of the glass substrates 13 and 14, and the alignment film 22 made of polyimide resin or the like is formed on the transparent electrode layers 20 and 21, respectively. 23 are provided. Due to the relationship between the alignment films 22 and 23, the liquid crystal in the liquid crystal layer 15 is twisted by 240 degrees.
[0048]
Further, a color filter (not shown) may be formed between the back glass substrate 14 and the transparent electrode layer 21 by printing or the like so that the liquid crystal display device can perform color display.
[0049]
In the liquid crystal display device of the present embodiment, as described above, the reflector 1 itself has both high reflectivity over a wide reflection angle and appropriate directivity, so that the direction in which the user normally looks at the display surface can be changed. As a center, a display surface having a wide viewing angle and sufficient brightness can be obtained.
[0050]
In the reflective liquid crystal display device of the present embodiment, the example in which the reflector is a so-called external reflector disposed outside the second polarizing plate has been described. A built-in type may be provided on the side. Further, although the STN type has been described as an example of the liquid crystal display device, the reflector of the present invention is also applied to a TN (Twisted Nematic) type liquid crystal display device in which the twist angle of the liquid crystal molecules in the liquid crystal layer is set to 90 degrees. Of course you can.
[0051]
【The invention's effect】
  As described above in detail, in the reflector according to the present invention, the inner surface is formed by connecting the peripheral curved surface, which is a part of two spherical surfaces having different radii, and the bottom curved surface located at the position surrounded by the peripheral curved surface. From the face,And the inner surface of the recess is composed of two spherical surfaces each having a different curvature radius, one is a peripheral curved surface, and the other is a bottom curved surface,The spherical surface that forms the peripheral curved surfacecurvatureThe radius of the spherical surface forming the bottomcurvatureThe surface is formed with a number of recesses that are smaller than the radius and whose normals standing on the reflector surface from the center of each spherical surface are on different straight lines. Reflectance can be obtained, and appropriate directivity can be provided.
  In the reflector of the present invention, the inner surface of the plurality of recesses is mainly composed of the first curved surface portion and the second curved surface portion on the reflector surface, and the maximum luminance direction of the reflected light of the outside light according to the position of the second curved surface portion. Therefore, it is possible to obtain a good reflectivity with respect to a wide range of reflection angles and to have an appropriate directivity.
  In addition, according to the reflective liquid crystal display device of the present invention, the reflector having the above-described excellent characteristics provides a wide viewing angle and sufficient brightness centered on the direction desired by the user. A liquid crystal display device can be realized.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a reflector according to an embodiment of the present invention.
FIG. 2 shows the concave part 4 of the reflector, in which (a) is a sectional view and (b) is a plan view.
FIG. 3 is a process flow diagram showing the manufacturing process of the reflector step by step.
FIG. 4 is a view showing a manufacturing process of a mother die used for forming a reflector, and showing a state in which a mother die substrate is pressed with a diamond indenter.
FIG. 5 shows comparison data between the reflector and the reflection characteristics of a conventional reflection pair.
FIG. 6 is a perspective view showing a reflector according to another embodiment of the present invention.
FIG. 7 is a cross-sectional view showing a reflective liquid crystal display device according to an embodiment of the present invention.
FIG. 8 is a perspective view showing an example of a conventional reflector.
FIG. 9 is a view for explaining an inclination angle of an inner surface of a concave portion of a reflector.
FIG. 10 is a diagram for explaining an incident angle and a reflection angle.
FIG. 11 is a diagram for explaining a use state of a display device provided in a notebook personal computer.
FIG. 12 is a diagram illustrating a usage state of a horizontally provided display device.
[Explanation of symbols]
1 Reflector
2 Substrate
3 Resin base material (base material for reflector)
4 recess
4a Peripheral curved surface(First curved surface part)
4b Bottom curved surface(Second curved surface part)
5 Reflective film
7 Matrix base material
8 Diamond indenter
9 Reflector forming matrix
12 Transfer type

Claims (8)

A plurality of recesses are formed on the reflector surface, and the inner surface of the recesses is a surface in which a peripheral curved surface, which is a part of two spherical surfaces each having a different radius, and a bottom curved surface existing at a position surrounded by the peripheral curved surface. And the inner surface of the recess is composed of two spherical surfaces each having a different radius, one is a peripheral curved surface, and the other is a bottom curved surface, in the cross section of the spherical surface forming the peripheral curved surface A reflector having a radius of curvature smaller than a radius of curvature in a cross section of a spherical surface forming a bottom curved surface, and normals standing on the reflector surface from the center of each spherical surface exist on mutually different straight lines.   A number of concave portions are formed on the reflector surface, and the inner surface of the concave portion is composed of a main first curved surface portion and a second curved surface portion formed in the first curved surface portion, and the center of curvature of the second curved surface portion is A reflector that is different from the center of curvature of the first curved surface portion and has a maximum luminance direction of reflected light of external light set according to the position of the second curved surface portion.  2. The reflector according to claim 1, wherein normals standing on the surface of the reflector from the center of each spherical surface are separated by an interval in a range of 0.1 to 10 μm.  The inclination angle of the peripheral curved surface is set in the range of 10 to 35 degrees and −35 to −10 degrees, and the inclination angle of the bottom curved surface is set in the range of 4 to 17 degrees and −17 to −4 degrees, respectively. The reflector according to claim 1 or 2, wherein the reflector is characterized.  The reflector according to any one of claims 1 to 3, wherein the depth of the plurality of concave portions is randomly formed in a range of 0.1 to 3 µm.  The reflector according to any one of claims 1 to 4, wherein the plurality of concave portions are formed continuously with each other.  5. The reflector according to claim 1, wherein the plurality of concave portions are formed on the reflector surface together with the plurality of grooves.  A reflective liquid crystal display device comprising the reflector according to claim 1.

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