JP3623341B2 - Reflector and reflective liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reflector having high reflection efficiency over a wide range, and a reflective liquid crystal display device using the reflector.
[0002]
[Prior art]
In recent years, a reflective liquid crystal display device has been widely used as a display unit of a handy type computer or the like because of particularly low power consumption. This reflective liquid crystal display device is provided with a reflecting plate for performing display by reflecting light incident from the display surface side. As the conventional reflector, a reflector having a mirror-finished surface or a reflector having random irregularities formed on the surface has been used.
Among these, as shown in FIG. 7, the conventional reflector 60 provided with a random uneven surface is heated by a polyester film 61 having a thickness of 300 to 500 μm, for example, so that the surface has a height of several μm. An uneven surface 61a is formed, and a reflective film 62 made of aluminum, silver, or the like is formed on the uneven surface 61a using a method such as vapor deposition.
[0003]
As shown in FIG. 8, the conventional reflection type liquid crystal display device using this type of reflection plate 60 is provided with transparent electrode layers 53 and 54 on the facing surfaces of a pair of glass substrates 51 and 52, respectively. A liquid crystal alignment film 55, 56 is provided on each of the transparent electrode layers 53, 54, and a liquid crystal layer 57 is disposed between the alignment films 55, 56. The first and second polarizing plates 58 and 59 are provided outside the glass substrates 51 and 52, respectively. The reflecting plate 60 is provided outside the second polarizing plate 59, and the surface on the reflecting film 62 side is the second polarizing plate. It is attached toward the plate 59 side.
[0004]
In the reflective liquid crystal display device 50 configured as described above, the light incident on the first polarizing plate 58 is linearly polarized by the polarizing plate 58, and the polarized light is elliptically polarized by passing through the liquid crystal layer 57. Then, the elliptically polarized light is linearly polarized again by the second polarizing plate 59, and this linearly polarized light is reflected by the reflection plate 60 and again passes through the second polarizing plate 59 and the liquid crystal layer 57. Then, the light is emitted from the first polarizing plate 58.
[0005]
Here, the following can be said about the reflection characteristics with respect to the incident light in the reflector and the reflective liquid crystal display device.
As shown in FIG. 7, when the incident angle of the incident light J from the point light source arranged on the reflecting film 62 is constant at an incident angle of 30 degrees with respect to the normal to the surface of the reflecting film 62, the reflected light K is reflected. When the reflectance when the angle θ is changed from 0 degree to 60 degrees is measured, the reflectance is approximately 1100% at the reflection angle of 30 degrees, and the reflectance is almost equal at the left and right reflection angles of 20 degrees or less and 40 degrees or more. It turned out to be the lowest. This tendency is the same not only when the reflection plate is measured alone, but also when measured as a liquid crystal display device equipped with this reflection plate. The reflection angle has a peak reflectance of about 100% at a reflection angle of 30 degrees. It has been found that it falls to almost 0% in the range of 23 degrees or less to 37 degrees or more.
[0006]
In addition, regarding the reflection characteristics of the reflection plate having a mirror surface, the reflection characteristic is generally very high at a specific reflection angle with respect to the incident angle as compared with a reflection plate having random irregularities on the surface. However, it has a characteristic that the range of the reflection angle with high reflectivity is extremely narrow, that is, the viewing angle is narrow.
[0007]
[Problems to be solved by the invention]
As described above, the conventional reflector having a random concavo-convex reflecting surface has a low reflection efficiency due to poor reflection efficiency, and is sufficient for the need for a reflector that reflects incident light at a wider range of reflection angles. I couldn't respond. Therefore, the reflective liquid crystal display device using this type of reflector has a problem that the viewing angle is as narrow as about 25 to 35 degrees and the brightness of the display surface is not sufficient.
[0008]
Therefore, in order to solve this problem, a reflector having a large number of stripe grooves extending linearly on the surface has been proposed. However, in the case of this reflector, with respect to the direction perpendicular to the stripe groove, a desired brightness can be obtained with respect to a certain range of reflection angle, but the reflection angle range is narrow, and further, with respect to directions other than the direction perpendicular to the stripe groove. In the first place, the reflectance was low and the reflection angle was extremely narrow. Therefore, when this type of reflector is applied to a liquid crystal display device, the above-mentioned problems such as a narrow viewing angle and insufficient brightness of the display surface, particularly in a direction parallel to the stripe groove, cannot be solved. It was.
[0009]
The present invention has been made to solve the above-described problems, and has a wide range of reflection angles and can improve the reflection efficiency, and any reflector using such a reflector. An object is to provide a reflective liquid crystal display device having a wide viewing angle in the direction and a bright display surface.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the reflector of the present invention is provided on the surface.Arc-shapedGrooveMultiple, individually aligning their curve directionsIsIncident light from a light source disposed above the plurality of grooves can be reflected freely.The configuration. In this reflector, when light is incident from a direction perpendicular to the groove, the surface on which the light strikes is curved, so that the reflection angle of the light can be further widened compared to the case where the groove is linear. .
[0011]
Here, the bending radius R of the curved groove (hereinafter referred to as a curved groove) can be appropriately set according to the size of the display screen of the liquid crystal display device to be applied. For example, it is desirable that 20 mm ≦ R ≦ 100 mm for a screen with a size of 2 to 4 inches and 100 mm ≦ R ≦ 300 mm for a screen with a size of 4 to 7 inches. The reason is that if the radius of curvature R is too small, the light from the front of the screen cannot be used effectively, and if R is too large, the light collection efficiency of the light from the surroundings becomes low.
The groove depth of the curved groove is preferably 1 to 3% of the radius of the inner curved surface of the curved groove. The reason for this is that if it is less than 1%, the angle of inclination of the curved surface in the curved groove with respect to the horizontal plane becomes small, so that it becomes a reflection characteristic close to regular reflection, which improves the reflection characteristic for light incident from a direction orthogonal to the curved groove. This is because the light cannot be collected at an effective viewing angle if it exceeds 3%.
The groove width w of the curved groove is preferably 25 μm ≦ w ≦ 75 μm. The reason is that when the width w is less than 25 μm, an interference color is seen when the curved groove is formed to have the same width, and when it exceeds 75 μm, the stripe pattern by the ridge line portion of the groove is visually observed.
[0012]
In addition to the curved groove, a large number of linear grooves intersecting with the curved groove may be provided continuously. In the case where this linear groove (hereinafter referred to as a linear groove) is provided, light incident from the direction along the curved groove is reflected in a wide range by the linear groove portion, so that in addition to the direction orthogonal to the curved groove, The reflection angle of light can be widened also with respect to incident light from the direction along the curved groove. In addition, these many linear grooves may be provided radially, and may be provided so that each extends in parallel.
[0013]
In the case of the reflector provided with the linear groove, the groove width of the linear groove is desirably 30% or less of the groove width w of the curved groove. The reason is that when the groove width of the straight groove exceeds 30% of the groove width w of the curved groove, the reflection characteristics of the straight groove become too dominant, and the shape effect of the inclined surface of the curved groove is diminished, and the light falls within the effective range. This is because the light is not collected efficiently.
The groove depth of the straight groove is preferably 1 to 3% of the radius of the inner curved surface of the straight groove. The reason for this is that if it is less than 1%, the angle of inclination of the curved surface in the straight groove with respect to the horizontal plane becomes small, and the reflection characteristics for light incident from the direction along the curved groove cannot be improved, and it exceeds 3%. This is because the light is diffusely reflected and the light cannot be efficiently collected at the effective viewing angle.
The interval between the linear grooves is preferably 1.1 to 3 times the groove width of the linear grooves. The reason is that if it is less than 1.1 times, the shape of the straight groove is distorted due to plastic deformation when forming a close linear groove, and the desired reflection characteristics cannot be obtained. This is because, since the groove interval is too wide, the reflection characteristic of the curved groove becomes dominant, and the reflection characteristic with respect to light incident from the direction along the curved groove cannot be improved.
[0014]
The reflective liquid crystal display device of the present invention is characterized by comprising the reflector as described above, that is, a reflector in which a large number of grooves having a planarly curved shape are provided on the surface. . This reflector may be either an external type or a built-in type.
According to the reflection type liquid crystal display device of the present invention, as described above, the reflector itself has high reflection efficiency and a wide range of reflection directions. Therefore, the reflection type liquid crystal display device in any direction as compared with the conventional reflection type liquid crystal display device. The viewing angle is widened and the entire display surface can be brightened.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a reflector according to a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a reflector according to the present embodiment. As shown in this figure, in the reflector 1 of the present embodiment, a large number of curved grooves 3 having the same groove width and groove depth are continuously provided on the surface of a substrate 2 made of a metal material such as pure aluminum. It is a thing.
[0016]
The bending radius R of the curved groove 3 can be set as appropriate depending on the size of the display screen of the liquid crystal display device to be applied. For example, it is desirable that 20 mm ≦ R ≦ 100 mm for a screen with a size of 2 to 4 inches and 100 mm ≦ R ≦ 300 mm for a screen with a size of 4 to 7 inches. This is because if the radius of curvature R is too small, light from the front of the screen cannot be used effectively, and if R is too large, the light collection efficiency of light from the surroundings becomes low.
The groove depth of the curved groove 3 is preferably 1 to 3% of the radius of the inner curved surface of the curved groove 3. If it is less than 1%, the inclination angle of the inner curved surface of the curved groove 3 with respect to the horizontal plane becomes small, so that reflection characteristics close to regular reflection can be obtained, and the reflection characteristics for light incident from a direction orthogonal to the curved groove 3 can be improved. In addition, if it exceeds 3%, light cannot be collected at an effective viewing angle.
The groove width w of the curved groove 3 is preferably 25 μm ≦ w ≦ 75 μm. This is because when the width w is less than 25 μm, an interference color is seen when the curved groove 3 is formed to have an equal width, and when it exceeds 75 μm, a striped pattern due to the ridge line portion of the curved groove 3 is visually observed.
[0017]
When manufacturing the reflector 1 having the above-described structure, first, a bit 2 is pressed against the outer peripheral portion of the surface of the substrate 2 while rotating the substrate 2 made of a pure aluminum donut-shaped disk on a rotary table. The surface of the substrate 2 is cut by moving the substrate 2 toward the center of rotation. In this way, the spiral curved groove 3 is formed on the surface of the substrate 2. And the reflector 1 of this Embodiment is obtained by cutting out a rectangular board from this disc.
[0018]
In this reflector 1, when light is incident from a direction orthogonal to the curved groove 3, the reflection surface to which the incident light hits is curved, so that the conventional reflection in which the surface is in a mirror state or random irregularities are formed. The light reflection angle can be made wider than that of the plate.
[0019]
Hereinafter, a reflector according to a second embodiment of the present invention will be described with reference to the drawings.
FIG. 2 is a diagram showing a reflector according to the present embodiment. As shown in this figure, the reflector 5 of the present embodiment is provided with a large number of curved grooves 7 having the same groove width and groove depth on the surface of a substrate 6 made of a metal material such as pure aluminum. In addition, a large number of linear grooves 8 having the same groove width, groove depth, and interval between the grooves are arranged in a radial pattern so as to be orthogonal to the curved grooves 7.
[0020]
Preferred ranges of the bending radius, groove depth, and groove width w of the curved groove 7 are as described in the section of the first embodiment.
On the other hand, regarding the straight groove 8, it is desirable that the groove width is 30% or less of the groove width w of the curved groove. If the groove width of the straight groove 8 exceeds 30% of the groove width w of the curved groove 7, the reflection characteristic of the straight groove 8 becomes too dominant, and the shape effect of the inclined surface of the curved groove 7 is diminished, so that the light falls within the effective range. This is because the light is not collected efficiently.
The groove depth of the straight groove 8 is preferably 1 to 3% of the radius of the inner curved surface of the straight groove 8. If it is less than 1%, the inclination angle of the inner curved surface of the straight groove 8 with respect to the horizontal plane becomes small, and the reflection characteristics for light incident from the direction along the curved groove 7 cannot be improved. This is because irregular reflection occurs and light cannot be efficiently collected at an effective viewing angle.
The interval between the straight grooves 8 is preferably 1.1 to 3 times the groove width of the straight grooves 8. If it is less than 1.1 times, the shape of the linear groove 8 is distorted due to plastic deformation when forming the close linear groove 8, and the desired reflection characteristics cannot be obtained. This is because the reflection characteristic for the light incident from the direction along the curved groove 7 cannot be improved.
[0021]
When manufacturing the reflector 5 having the above-described configuration, first, a cutting tool is pressed against the outer peripheral portion of the surface of the substrate 6 while the substrate 6 made of a pure aluminum donut-shaped disk is placed on a rotary table and rotated. Then, the substrate 6 is moved toward the rotation center of the substrate 6 to cut the surface of the substrate 6 to form a spiral curved groove 7 on the surface of the substrate 6. Next, while pressing an indenter made of diamond to the inner peripheral portion of the surface of the substrate 6 where the curved groove 7 is formed with a constant load, the indenter is moved toward the outer peripheral portion along a straight line extending in the radial direction from the center of the substrate 6. Then, the linear groove 8 orthogonal to the curved groove 7 is formed while plastic deformation is applied to the surface of the substrate 6. Subsequently, another straight groove 8 is formed in the same manner as the above-described straight groove 8 along a straight line that forms a predetermined angle with the straight line passing through the center of the substrate 6. The formation of the groove 8 is repeated. Finally, a reflector 5 of the present embodiment is obtained by cutting a rectangular plate from the circular plate.
[0022]
Also in the reflector 5, as in the reflector of the first embodiment, an effect that the reflection angle with respect to the incident light from the direction orthogonal to the curved groove 7 is widened can be achieved. Further, in the case of the present embodiment, in addition to the effect, the light incident from the direction along the curved groove 7 is reflected in a wide range at the portion of the straight groove 8, and becomes incident light from the direction along the curved groove 7. In contrast, the reflection angle of light can be widened.
[0023]
In the present embodiment, an example in which a large number of linear grooves 8 are provided radially has been described. However, the linear grooves may extend in parallel. In the first and second embodiments, the groove width, the groove depth, and the groove interval of the curved groove and the straight groove are all described as being equal. However, the present invention is not limited to this configuration. In each groove, the groove width, groove depth, and groove interval of each groove may be different within the above-described preferable numerical range.
[0024]
Moreover, although the said 1st, 2nd embodiment was an example using the aluminum plate which formed many curved grooves and linear grooves on the surface as a reflector as it is, it replaces with this form and is as follows. It is good also as a simple structure.
First, a large number of curved grooves or straight grooves are formed on the surface of an arbitrary metal plate using the same method as described above. Then, using this metal plate as a mother mold, a resin material such as silicone is poured onto the surface on which the groove is formed and cured, thereby creating a transfer mold having an uneven shape opposite to the mold surface of the mother mold. Thereafter, the mold surface of the transfer mold is pressed against the surface of the resin substrate made of a resin material for the reflector, and the curved grooves or linear grooves similar to the mold surface of the mother mold are transferred to the surface of the resin substrate. Finally, a reflector is obtained by forming aluminum or the like on the surface of the resin base material in which the grooves are formed to form a reflective film. You may use this reflector.
[0025]
Next, an STN (Super Twisted Nematic) reflective liquid crystal display device using the reflector according to the present invention will be described.
As shown in FIG. 3, this reflective liquid crystal display device is provided with a liquid crystal layer 15 between a pair of a 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. The second polarizing plate 18 and the plate-like reflector 1 or 5 shown in FIG. 1 or 2 are sequentially provided on the lower surface side of the back side glass substrate 14.
[0026]
The reflector 1 or 5 is laminated so that the surface on which the groove is formed on the lower surface side of the second polarizing plate 18 is opposed, and between the second polarizing plate 18 and the reflector 1 or 5, such as glycerin. An adhesive 19 made of a material that does not adversely affect the refractive index of light 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 and the like, the liquid crystal in the liquid crystal layer 15 is twisted by 240 degrees.
[0027]
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.
[0028]
In the liquid crystal display device according to the present embodiment, as described above, the reflector 1 or 5 itself has the characteristics that the reflection angle of incident light is wide and the reflection efficiency is high. Even when viewed from the direction, the viewing angle is wider than that of the conventional liquid crystal display device, and a bright display surface can be obtained.
[0029]
In the reflection type liquid crystal display device of the present embodiment, an example in which the reflection plate is a so-called external reflection plate arranged outside the second polarizing plate has been described, but may be a built-in type. Although the STN type liquid crystal display device 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, it can be applied.
[0030]
【Example】
Next, a description will be given of the result of actually evaluating the reflection characteristics using the reflector having the curved groove and the reflector having both the curved groove and the straight groove described as the first and second embodiments.
Example 1
Example 1 is an example of a reflector having only a curved groove on the surface shown as the first embodiment. A donut-shaped disk having an outer diameter of 200 mm and an inner diameter of 110 mm was used as a pure aluminum material serving as a base material for the reflector. While this was placed on a rotary table and rotated, the disk surface was cut using a cutting tool having a radius of 100 μm to form a spiral curved groove. Then, a square plate having a side of 30 mm was cut out from this disk, and the reflector of Example 1 was obtained. This reflector has a curved radius of the curved groove of 60 to 100 mm, a groove width of 45 to 55 μm, and a groove depth of 3.0 to 3.4 μm.
[0031]
(Example 2)
Example 2 is an example of a reflector having a curved groove and a straight groove on the surface shown as the second embodiment. The pure aluminum disk used as the base material of the reflector and the cutting tool used for forming the curved groove are the same as those used in Example 1. Then, after using these to form a curved groove on the disk surface, a linear groove perpendicular to the curved groove was formed on the disk surface using an indenter made of diamond having a tip radius of 8 μm. Then, after repeating the formation of this linear groove, a square plate having a side of 30 mm was cut out from this disk, and the reflector of Example 2 was obtained. As in Example 1, this reflector has a curved radius of the curved groove of 60 to 100 mm, a curved groove width of 45 to 55 μm, a curved groove depth of 3.0 to 3.4 μm, and a straight groove. The groove width is 5 to 6 μm, the groove depth of the straight groove is 0.4 to 0.6 μm, and the width of the straight groove is 6.5 to 7.5 μm at the position of the curved groove where the width between the grooves is 60 mm. It has 13 to 15 μm at a position of a curved width of 100 mm.
[0032]
4 and 5 show the reflection characteristics in the direction perpendicular to the curved groove and in the direction along the curved groove for each of the reflectors of Example 1 and Example 2 created as described above. .
These figures are graphs showing a reflection characteristic curve with the vertical axis representing the reflectance (reflection intensity) and the horizontal axis representing the reflection angle. The reflection characteristic curve in the figure is arranged on the reflector as shown in FIG. Incident light L from a point light source₀Is an incident angle θ as viewed from the normal H in a plane including a normal H standing on the surface of the reflective film and an incident ray for measuring reflection characteristics.₀When the incident angle is 30 degrees, the reflectance when the reflection angle θ of the reflected light L is changed from 0 to 60 degrees is plotted. The reflectance is reflected light at a reflection angle of 30 degrees when a white plate (plate with a MgO standard white surface) is irradiated at an incident angle of 30 degrees using a liquid crystal panel evaluation apparatus (LCD5000 model manufactured by Otsuka Electronics Co., Ltd.). The output of the reflected light is divided by the reference output and expressed as a percentage (%).
[0033]
4 and 5, the angles indicated as “0 degrees and 90 degrees” are, as shown in FIG. 6, a normal H standing on the surface of the reflector and a straight line perpendicular to the curved groove. And the incident ray L for measuring the normal H and the reflection characteristic.₀It is an angle ψ formed by a plane including. Therefore, the characteristic curve of 0 degree (shown by a solid line) has an incident angle θ with respect to the normal from the direction perpendicular to the curved groove.₀The reflection characteristic with respect to light incident at 30 degrees is measured, and the characteristic curve of 90 degrees (shown by a broken line) is an incident angle θ with respect to the normal from the tangential direction of the curved groove.₀= Measurement of reflection characteristics for incident light at 30 degrees.
[0034]
In the case of the reflector of Example 1 having only a curved groove, as shown in FIG. 4, the reflection characteristic for incident light from the direction orthogonal to the curved groove (shown by a 0-degree reflection characteristic curve) has a reflection angle of 0 degrees. It has a number of peaks over a wide range of 50 to 50 degrees, and a reflection intensity of 500% or more was secured in this range, but the reflection characteristic (90 degree reflection characteristic curve) with respect to incident light from the direction along the curved groove is conventional. Similarly, only a narrow peak centered at a reflection angle of 30 degrees was obtained.
On the other hand, in the case of the reflector of Example 2 having a curved groove and a linear groove, as shown in FIG. 5, either incident light from a direction orthogonal to the curved groove or incident light from a direction along the curved groove is used. Although the reflection intensity was not so high as 500% or less, a characteristic in which a certain degree of reflection intensity was widely distributed over the range of the reflection angle from 0 degree to 50 degrees could be obtained.
[0035]
As is apparent from the above data, the reflection characteristic for incident light from the direction orthogonal to the groove can be improved by bending the groove provided on the reflector surface, and the curved groove can be obtained by adding a linear groove. As a result, it has been proved that the reflection characteristics for incident light from all directions are improved according to the reflector of the present invention.
[0036]
【The invention's effect】
As described above in detail, in the reflector of the present invention, the surfaceArc-shapedGrooveMultiple, individually aligning their curve directionsIsThe incident light from the light source arranged above the outside of the plurality of grooves can be reflected freely.Accordingly, when light enters the arc-shaped groove from an external direction orthogonal to the groove, the reflection angle of the light can be further widened.
Also, aboveArc-shapedWhen a straight groove is provided in addition to the groove,Arc-shapedLight incident from the direction along the groove is reflected in a wide range at the straight groove part,Arc-shapedIn addition to the direction perpendicular to the grooveArc-shapedThe reflection angle of light can be widened also with respect to incident light from the direction along the groove.
Therefore, according to the reflective liquid crystal display device of the present invention, since the reflector itself has a high reflection efficiency and a wide range of reflection directions, the viewing angle is larger in any direction than the conventional reflective liquid crystal display device. It spreads and the display surface can be brightened as a whole.
The reflector of the present invention is applied to a display screen having a size of 2 to 4 inches, and the curved radius R of the arc-shaped groove is 20 to 100 mm, or a display screen having a size of 4 to 7 inches. If the radius of curvature R of the arc-shaped groove is 100 to 300 mm, the light from the front of the display screen can be used effectively, and the light collection efficiency from the surroundings can be increased. .
In the reflector of the present invention, if the depth of the arc-shaped groove is 1 to 3% of the radius of the inner curved surface, the inclination angle of the inner curved surface of the arc-shaped groove with respect to the horizontal plane can be preferably set. The reflection characteristic with respect to the light incident from the direction orthogonal to the groove of the mold can be improved, and the light can be condensed at an effective viewing angle.
In the reflector of the present invention, if the width of the arc-shaped groove is in the range of 25 to 75 μm, the interference color is not visible, and the stripe pattern by the ridge line portion of the arc-shaped groove is visually observed. Nor.
In the reflector of the present invention, if the width of the linear groove is within 30% of the width of the arc-shaped groove, the reflection characteristic of the linear groove does not become too dominant, and the arc-shaped groove The shape effect of the inclined surface of the groove can be exhibited, and the light can be efficiently collected in the effective range.
In the reflector of the present invention, if the depth of the linear groove is in the range of 1 to 3% of the radius of the inner curved surface of the arc-shaped groove, the straight line with respect to the horizontal plane is less than 1%. The inclination angle of the inner curved surface of the groove becomes small, and the problem that the reflection characteristic for the light incident from the direction along the curved groove cannot be improved can be eliminated. Thus, the light can be efficiently collected without the problem that the light cannot be efficiently collected at the effective viewing angle.
In the reflector according to the present invention, the interval between the linear grooves is 1 of the width of the linear grooves. . If it is within the range of 1 to 3 times, it is possible to avoid the problem that the shape of the linear groove is distorted due to plastic deformation when forming a close linear groove when it is less than 1.1 times. The reflection characteristic of the curved groove becomes too dominant when it exceeds 3 times, and the reflection characteristic for the light incident from the direction along the curved groove cannot be improved. Can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a first embodiment of a reflector according to the present invention.
FIG. 2 is a perspective view showing a second embodiment of a reflector according to the present invention.
FIG. 3 is a cross-sectional view showing an embodiment of a reflective liquid crystal display device according to the present invention.
FIG. 4 is a graph showing the reflection characteristics of the reflector of Example 1 according to the present invention.
FIG. 5 is a graph showing the reflection characteristics of the reflector of Example 2.
6 is a diagram for explaining reflection angles θ and ψ in FIGS. 4 and 5. FIG.
FIG. 7 is a perspective view showing an example of a conventional reflector.
FIG. 8 is a cross-sectional view showing an example of a conventional reflective liquid crystal display device.
[Explanation of symbols]
1,5 reflector
2,6 substrate
3,7 Curved groove
8 Straight groove

Claims (10)

A plurality of arc-shaped grooves on the surface are individually arranged with their curved directions aligned , so that incident light from a light source arranged above the plurality of grooves can be reflected freely. body. Reflector according to claim 1 in which a plurality of linear grooves intersecting the plurality of grooves of the circular arc type, characterized in that it is continuously provided. The reflector according to claim 1 or 2, wherein the reflector is applied to a display screen having a size of 2 to 4 inches, and a radius of curvature R of the arc-shaped groove is 20 to 100 mm. The reflector according to claim 1 or 2, wherein the reflector is applied to a display screen having a size of 4 to 7 inches, and a radius of curvature R of the arc-shaped groove is 100 to 300 mm. 5. The reflector according to claim 1, wherein a depth of the arc-shaped groove is 1 to 3% of a radius of the inner curved surface. The reflector according to any one of claims 1 to 5, wherein a width of the arc-shaped groove is in a range of 25 to 75 µm. 7. The reflector according to claim 2, wherein a width of the linear groove is within 30% of a width of the arc-shaped groove. The reflector according to any one of claims 2 to 7, wherein a depth of the linear groove is in a range of 1 to 3% of a radius of an inner curved surface of the arc-shaped groove. The reflector according to any one of claims 2 to 8, wherein an interval between the linear grooves is within a range of 1.1 to 3 times a width of the linear grooves. Reflection type liquid crystal display device characterized by comprising a reflector according to any one of claims 1-9.

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