JP2004102126A - Method for manufacturing reflector and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form the rugged shapes of a surface simply and with good controllability in a method for manufacturing a reflector used for a liquid crystal display device, etc., of a reflection type or semi-tranparent reflection type and a liquid crystal display provided with the reflector. <P>SOLUTION: Projecting parts 119 consisting of a photosensitive resin are patterned and formed on a substrate 111 by forming a photosensitive resin layer on the substrate, then exposing and developing the photosensitive resin layer through a photomask formed of a plurality of the prescribed patterns. The surface of the projecting parts 119 are processed by blowing reactive etching gas on the surface of the substrate 111 or irradiating the surface with an electron beam 400 from a direction making a prescribed angle θ with the X-axis of a coordinate system having the normal direction of the substrate 111 as the Z-axis direction, thereby forming a reflection layer on the surface of the substrate 111 having the projecting parts 119 formed thereon. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a reflector used in a reflective or transflective liquid crystal display device and the like, and a liquid crystal display provided with the reflector.
[0002]
[Prior art]
2. Description of the Related Art With the development of portable information terminal devices, liquid crystal display devices that are small, light, and excellent in portability have been widely used. Above all, the importance of the reflection type liquid crystal display device has been increasing in recent years because a backlight is not required, so that power consumption can be significantly reduced and further reduction in thickness and weight can be achieved. In such a reflective liquid crystal display device, in order to realize a bright display in a wide viewing angle range, a diffuse reflector having random irregularities formed on the surface is provided on the back side of the liquid crystal layer, and the light is incident from the display surface side. The display is performed by diffusing and reflecting the external light.
[0003]
As a method of manufacturing the reflector having the unevenness on the surface as described above, for example, a method of patterning a photosensitive resin to form the unevenness (see Patent Document 1) or a method of removing wrinkles formed by heat shrinkage of a film. A method of using as unevenness has been proposed.
[0004]
In the manufacturing method for patterning a photosensitive resin, for example, as shown in FIG. 16, first, a photosensitive resin 1001 is applied onto a substrate 1000 made of glass or the like (see FIG. 16A), and A rectangular uneven portion 1001a is formed by patterning into a predetermined shape by lithography (see FIG. 16B). Next, after the uneven portion 1001a is subjected to a heat treatment to smooth the corners of the uneven portion 1001a by flowing, a resin 1002 is applied on the uneven portion 1001a (see FIG. 16C). As a result, the space between the adjacent uneven portions 1001a is filled with the resin 1002, and smooth curved unevenness is formed on the substrate surface. Finally, a reflector is manufactured by forming a reflective layer 1003 made of a metal film such as aluminum or silver on the resin 1002 by a method such as vapor deposition (see FIG. 16D).
[0005]
In the method using the heat shrinkage of the film, for example, as shown in FIG. 17, first, a resin layer 1101 having a thickness of 50 to 500 μm is applied on a substrate 1100 made of glass or the like (see FIG. 17A). . Next, the resin layer 601 is subjected to a heat treatment to thermally shrink the surface, and a random uneven surface 601a having a height of about several μm is formed on the surface. Finally, a reflector is manufactured by forming a reflective layer 1102 made of aluminum, silver, or the like on the uneven surface 601a by using a method such as vapor deposition (see FIG. 17C).
[0006]
[Patent Document 1]
JP-A-11-248909
[0007]
[Problems to be solved by the invention]
By the way, when the surface shape of the concave and convex portions of the reflector is controlled with sufficient accuracy, reflection of unnecessary light from inside and outside can be suppressed, and light can be efficiently reflected in a required direction. For this reason, controlling the shape of the unevenness is an important issue in improving the display quality. However, in each of the above-described methods, it is difficult to form the concavo-convex surface by controlling it to a desired shape.
The present invention has been made in view of the above-described problems, and provides a method of manufacturing a reflector and a liquid crystal display device including the reflector, which can easily form unevenness on the surface with good controllability. With the goal.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a method of manufacturing a reflector according to the present invention includes a resin layer forming step of forming a photosensitive resin layer on a substrate, and the photosensitive layer through a photomask on which a plurality of predetermined patterns are formed. A patterning step of exposing and developing the resin layer to form a pattern of the photosensitive resin on the substrate in plan view; and a coordinate system in which the normal direction of the substrate is the Z-axis direction. A surface processing step of irradiating or spraying an etching material on the surface of the substrate from a direction forming a predetermined angle to process the surface of the convex portion, and forming a reflective layer on the surface of the substrate on which the convex portion is formed And a step of performing
[0009]
According to the present manufacturing method, since the etching material is irradiated obliquely from a direction forming a predetermined angle with respect to the Z axis, the projection formed on the substrate is perpendicular to the substrate including the irradiation direction of the etching material. In a cross section cut along a simple plane, the shape of the projection can be asymmetric. Therefore, directivity is generated in the reflection characteristics of the reflector, and a bright display can be obtained in a specific observation direction.
Further, in the present manufacturing method, since the surface shape of the projection is processed by the photolithography technique, a relatively large area can be processed in a single step, and the productivity is high.
[0010]
In addition, the method for manufacturing a reflector according to the present invention includes a resin layer forming step of forming a photosensitive resin layer on a substrate, and exposing and developing the photosensitive resin layer via a photomask having a plurality of predetermined patterns formed thereon. And a patterning step of patterning the convex portion made of the photosensitive resin on the base material in a plan view, and a predetermined angle with respect to the Z axis in a coordinate system in which the normal direction of the base material is the Z axis direction. A surface processing step of irradiating or spraying an etching material on the surface of the base material from the direction in which the base material is formed to process the surface of the convex portion, and molding the uneven shape of the surface of the base material formed by the convex portion. A step of forming a transfer mold, a resin layer forming step of forming a photosensitive resin layer on a substrate, a step of transferring irregularities on the surface of the transfer mold to the resin layer, and a step in which the irregularities are transferred. Forming a reflective layer on the surface of the substrate Characterized by comprising a.
[0011]
That is, in the present manufacturing method, a transfer mold is once manufactured using the uneven shape formed on the base material as a master mold, and the surface shape of the transfer mold is transferred to form the uneven shape on the photosensitive resin of the substrate. . Therefore, according to the present manufacturing method, since the concavo-convex surface having the same shape can be formed by such a transfer die, the manufacturing time can be significantly reduced, the waste of members and the like can be reduced, and the manufacturing cost can be significantly reduced.
[0012]
It is preferable that the pattern of the photomask used in the patterning step has a substantially circular or substantially elliptical shape, and the diameter of the pattern and the interval between adjacent patterns are randomly configured.
According to this manufacturing method, a plurality of substantially circular or substantially elliptical convex portions having different diameters in plan view are formed at random intervals in the substrate surface. For this reason, when such a resin pattern is subjected to a surface treatment in the surface processing step, the inclination angle of the surface of the convex portion with respect to the substrate surface varies irregularly within the substrate surface, and the reflection to the convex portion is caused. By forming the layer, a form having a wide viewing angle can be obtained.
[0013]
In the patterning step, it is preferable that the photosensitive resin layer is exposed to light through a photomask whose light transmittance is adjusted for each of the patterns, and that the resistance to the etching material is adjusted for each of the protrusions.
According to the present manufacturing method, the height distribution of the protrusions after the surface processing step can be made random within the substrate surface. For this reason, it is possible to further broaden the wide reflection form of the obtained reflector.
[0014]
Further, in the surface processing step, the etching material may be irradiated while rotating the irradiation angle in the azimuth direction within a predetermined angle range while keeping the irradiation angle in the polar angle direction constant.
According to this manufacturing method, since the surface shape of the convex portion can be controlled in detail, the degree of freedom in designing the reflection characteristics can be increased.
[0015]
Further, a liquid crystal display device according to the present invention includes a reflector manufactured by the above-described method for manufacturing a reflector.
According to this configuration, a bright display with a wide viewing angle can be obtained.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
[First Embodiment]
[Reflector and manufacturing method thereof]
FIG. 1 is a schematic diagram showing the configuration of a reflector of the liquid crystal display device according to the first embodiment of the present invention. FIGS. Are process diagrams for explaining the manufacturing process, FIG. 7 is an enlarged view of a main part showing a configuration of a photomask used for manufacturing a reflector, and FIGS. 8 to 11 show a liquid crystal display device of the present embodiment. FIG. In all of the following drawings, the thickness of each component, the ratio of dimensions, and the like are appropriately changed in order to make the drawings easy to see.
[0017]
As shown in FIG. 1A, the reflector 1 of the present embodiment is formed on a substantially circular or substantially elliptical projection 119 formed in an island shape on a substrate 111 made of glass or the like. The reflective layer 120 has a structure in which a reflective layer 120 made of a metal film having high reflectivity such as aluminum (Al) or silver (Ag) shown in FIG.
The convex portion 119 is made of a positive photosensitive resin such as an acrylic resist, an azide resist, an epoxy resist, a polystyrene resist, and an imide resist, and has a smooth curved surface shape.
[0018]
FIG. 2A is an enlarged perspective view showing one of the protrusions 119, and the surface of the protrusion 119 includes a first curved surface having a small curvature and a second curved surface having a large curvature. The first curved surface and the second curved surface are respectively gently formed on a first curve A extending from one peripheral portion S1 of the convex portion 119 to the top D and a first curve A in the X section shown in FIG. It has a shape shown by a second curve B continuously from the top D to the other peripheral part S2.
[0019]
The top D is located at a position shifted in the x direction from the center O of the projection 119 in a plan view, and is the average of the absolute values of the inclination angle of the first curve A with respect to the horizontal plane S of the substrate 111 and the inclination angle of the second curve B. The values are irregularly set in the angle ranges of 1 ° to 89 ° and 0.5 ° to 88 °, respectively, and the average value of the inclination angle of the first curve A is larger than that of the second curve B. ing. In addition, the inclination angle δa in the peripheral portion S1 of the first curve A indicating the maximum inclination angle varies irregularly within a range of approximately 4 ° to 35 ° at each convex portion 119. As a result, the heights H1 to H7 of the protrusions 119 (the height from the surface S of the substrate 111 to the top D of the protrusions 119) are irregularly varied in the range of 0.25 μm to 3 μm. .
[0020]
The first curved surface and the second curved surface have substantially symmetric shapes in the Y section shown in FIG. 2C, and the inclination angle θg of the outer peripheral surface is not in the range of −18 ° to + 18 °. The rules are set to vary.
The “inclination angle” of a curve or a curved surface refers to a horizontal plane of a curve or a curved surface (substrate) within an extremely small range of 0.5 μm, for example, at an arbitrary position on the curve or the curved surface. 111 refers to the angle with respect to the surface S).
[0021]
Further, the pitch of the protrusions 119 (the distance between the centers O of the adjacent protrusions 119) is randomly formed in the substrate surface, so that moire caused by the arrangement of the protrusions 119 can be prevented. .
[0022]
FIG. 3 is a diagram showing the reflection characteristics of the reflector 1 configured as described above. The substrate surface S is irradiated with external light from the x-direction side at an incident angle of 30 °, and the viewing angle is reduced. The light receiving angle θ and the brightness (when the light is swung from a position at 0 ° (perpendicular line) to a position at 60 ° with respect to the normal direction of the substrate surface S around a position at 30 ° which is the direction of regular reflection with respect to (Reflectance).
[0023]
As shown in FIG. 3, in the present reflector 1, the reflected light of light incident at an angle of 30 ° from the x direction side is higher on the lower angle side with respect to the reflection angle of 30 ° which is the regular reflection direction. Luminance is higher than on the angle side, and a peak of reflectance occurs around 20 °. This is because the top D of the convex portion 119 is shifted from the center O in the x direction, so that the ratio of light reflected on the second curved surface is larger than that reflected on the first curved surface. Can be In addition, the reflectance shows a gentle curve near 20 ° showing a peak, and the inclination angle of the surface of the convex portion 119 with respect to the horizontal plane S is irregularly varied for each convex portion 119, so that the viewing angle is reduced. It can be seen that a wide display was obtained.
[0024]
Next, a method for manufacturing the reflector 1 having the above configuration will be described with reference to FIGS.
First, as shown in FIG. 4A, a positive photosensitive resin 190 such as an acrylic resist, an azide resist, an epoxy resist, a polystyrene resist, or an imide resist is formed on a substrate 111 such as glass or plastic. Coating is performed by a coating method such as a spin coating method, a roll coater method, and a spraying method.
[0025]
Next, as shown in FIG. 4B, a photomask 300 is arranged close to the substrate 111, and the photosensitive resin 190 on the substrate 111 is irradiated with a light beam 301 such as an ultraviolet ray via the photomask 300. Exposure.
[0026]
The photomask 300 used here has a substantially circular shape or a substantially circular shape as shown by reference numerals T1 to T7 as shown in FIG. 7 corresponding to the planar shape of the convex portion 119 formed in an island shape shown in FIG. Many elliptical patterns are formed. The photomask 300 is a so-called gradation photomask in which the light transmission level of each pattern is adjusted in a plurality of levels (four to five levels). For example, the light transmittance levels t1 to t7 of the patterns T1 to T7 are t1>t2> t3 <t4>t5>t6> t7, and when viewed as a whole of the reflector 1, the exposure amount is The light transmission level of each pattern is set so as to be random.
[0027]
In the photosensitive resin layer 190 exposed through such a gradation photomask 300, a pattern with a large amount of exposure has a small etching resistance in an etching step described later, and a pattern with a small amount of exposure has a large etching resistance. When etching is performed, the height distribution of the patterned protrusions 119 can be irregularly varied within the substrate surface.
[0028]
Next, the photosensitive resin 190 is developed with an alkaline developer or the like, rinsed, and post-baked. As a result, as shown in FIG. 5, a substantially columnar or substantially elliptical columnar projection 119 having a substantially uniform height is formed in an island shape.
[0029]
Next, as shown in FIG. 6, the direction of the polar angle (that is, the angle formed with the Z axis) θ and the azimuth angle (that is, the angle formed with the X axis) φ is directed toward the substrate surface on which the convex portion 119 is formed. Then, dry etching (surface processing) is performed by irradiating an etching material 400 such as an electron beam, plasma, or a reaction gas containing chlorine (Cl). At this time, the azimuth angle φ is scanned in the range of, for example, + 40 ° to −40 ° while the polar angle θ is kept constant, and the surface of the convex portion 119 is processed into a shape as shown in FIG.
[0030]
As described above, when the etching material 400 is irradiated obliquely to the substrate surface from the direction forming the polar angle θ, the surface to which the gas 400 or the like is directly irradiated is sharply cut into a surface having a large curvature (second curved surface). The surface on the opposite side that has been processed and is not directly irradiated with the etching material 400 is processed into a surface having a small curvature (first curved surface) with the etching material 400 slightly wrapping around. By scanning the azimuth angle φ symmetrically with respect to the X axis, the shapes of the first curved surface and the second curved surface can be made symmetrical in the Y section as shown in FIG. 2C. Further, the inclination angle of the curved surface can be freely adjusted by the irradiation amount of the etching material 400.
[0031]
In the above-described dry etching step, the polar angle θ may be scanned in a predetermined angle range to control the shape of the protrusion 119 in more detail. At this time, by scanning the polar angle θ symmetrically with respect to the Z axis, it is possible to make the surface shape of the protrusion 119 symmetrical in both the X section and the Y section. In this case, the reflector 1 exhibits a substantially symmetrical reflection characteristic about the regular reflection angle.
[0032]
Finally, a reflective layer 120 made of a metal film having a high reflectivity such as Al or Ag is formed on the convex portion 119 processed as described above by a sputtering method, a CVD method, an ion beam method, or the like. The reflector 1 is completed.
[0033]
Therefore, according to the reflector of the present embodiment, since the first curved surface and the second curved surface of the convex portion 119 are configured to be asymmetric with respect to the top portion D, directivity is generated in the reflected light, and the reflected light has a specific observation direction. To increase the brightness of the display by collecting more reflected light. In addition, since the inclination angle of the outer peripheral surface of the convex portion 119 with respect to the substrate surface S and the height of the top D are irregularly varied for each convex portion 119, a display with a wide viewing angle can be obtained.
[0034]
According to the reflector manufacturing method of the present embodiment, since the etching material 400 is irradiated obliquely from a direction forming a predetermined angle θ with respect to the normal line (Z axis) of the substrate 111, The surface shape of the convex portion 119 formed on the substrate can be asymmetrical in the Y section. For this reason, directivity occurs in the reflection characteristics of the reflector 1 obtained by forming the reflection layer 120 on the convex portion 119 having such a surface shape, and a bright display can be obtained in a specific observation direction. .
[0035]
In addition, since the diameter of the substantially circular or substantially elliptical convex portion 119 in a plan view is randomly formed in the substrate surface, the inclination angle of the surface of each convex portion after dry etching with respect to the substrate horizontal plane S is set in the substrate surface. Irregularity can be obtained, and a display with a wide viewing angle can be obtained.
Further, when the photosensitive resin 190 is exposed, the exposure amount is adjusted for each of the protrusions 119 by the gradation photomask 300, so that the height distribution of the protrusions 119 after dry etching can be randomly determined in the substrate surface. can do. By forming the reflective layer 120 on such a convex portion 119, the viewing angle of display can be further widened.
[0036]
In addition, since the surface shape of the convex portion 119 changes by changing the irradiation angle (polar angle θ, azimuth angle φ), irradiation time (that is, irradiation amount) of the etching material 400, the reflection characteristics of the reflector 1 are compared. It can be controlled freely.
Further, in the present manufacturing method, since the surface shape of the projection 119 is processed by the photolithography technique, a relatively large area can be processed in a single step, and the production efficiency is high.
[0037]
[Liquid crystal display]
Next, as an example of the liquid crystal display device of the present invention, a reflective liquid crystal display device including the reflector of the present embodiment will be described.
[0038]
As shown in FIG. 8, the reflection type liquid crystal display device of the present embodiment includes a liquid crystal panel 100 as a main body and a front light 200 arranged on the front surface of the liquid crystal panel 100.
As shown in FIG. 8, the liquid crystal panel 100 includes an active matrix substrate 110, a counter substrate 140, and a liquid crystal layer 150 as a light modulation layer held between the substrates 110 and 140.
[0039]
As shown in FIG. 9, the active matrix substrate 110 includes a plurality of scanning lines 126 and signal lines in a row direction (x-axis direction) and a column direction (y-axis direction) on a substrate body 111 made of glass, plastic, or the like. The TFT (switching element) 130 is formed near the intersection of each scanning line 126 and the signal line 125. Hereinafter, the region where the pixel electrode 120 is formed, the region where the TFT 130 is formed, and the region where the scanning line 116 and the signal line 115 are formed on the substrate 110 are referred to as a pixel region, an element region, and a wiring region, respectively.
[0040]
The TFT 130 of the present embodiment has an inverted staggered structure, and a gate electrode 112, a gate insulating film 113, semiconductor layers 114 and 115, a source electrode 116, and a drain electrode 117 are formed in this order from the bottom layer of a substrate 111 serving as a main body. Have been. That is, a part of the scanning line 126 is extended to form the gate electrode 112, and the island-shaped semiconductor layer 114 is formed on the gate insulating layer 3 covering the gate electrode 112 so as to straddle the gate electrode 2 in plan view. A source electrode 116 is formed on one end of the semiconductor layer 114 via the semiconductor layer 115, and a drain electrode 117 is formed on the other end via the semiconductor layer 115.
[0041]
In addition to glass, an insulating substrate made of synthetic resin such as polyvinyl chloride, polyester, polyethylene terephthalate, or natural resin can be used for the substrate 111. Alternatively, an insulating layer may be provided on a conductive substrate such as a stainless steel plate, and various wirings and elements may be formed on the insulating layer.
[0042]
The gate electrode 112 includes a metal such as aluminum (Al), molybdenum (Mo), tungsten (W), tantalum (Ta), titanium (Ti), copper (Cu), chromium (Cr), or one or more of these metals. It is made of an alloy such as Mo-W, and is formed integrally with the scanning lines 125 arranged in the row direction as shown in FIG.
The gate insulating layer 113 is made of a silicon-based insulating film such as silicon oxide (SiOx) or silicon nitride (SiNy), and is formed on the entire surface of the substrate 111 so as to cover the scanning lines 126 and the gate electrodes 112.
[0043]
The semiconductor layer 114 is an i-type semiconductor layer made of amorphous silicon (a-Si) or the like without impurity doping, and a region facing the gate electrode 112 via the gate insulating layer 113 is configured as a channel region. .
The source electrode 116 and the drain electrode 117 are made of a metal such as Al, Mo, W, Ta, Ti, Cu, Cr or an alloy containing at least one of these metals, and sandwich a channel region on the i-type semiconductor layer 114. Are formed so as to face each other. The source electrode 116 is formed to extend from the signal line 125 provided in the column direction.
[0044]
Note that in order to obtain good ohmic contact between the i-type semiconductor layer 114 and the source electrode 116 and the drain electrode 117, phosphorus (P) or the like is provided between the i-type semiconductor layer 114 and each of the electrodes 116 and 117. An n-type semiconductor layer 115 doped with a high concentration of a group V element is provided. In an area between the source electrode 116 and the drain electrode 117, an inorganic insulating layer 118 made of a silicon-based insulating film such as silicon nitride (SiNy) is formed as an etching stopper layer for protecting a channel area. ing.
[0045]
An organic insulating layer 119 made of a positive photosensitive resin such as an acrylic resist, an azide resist, an epoxy resist, a polystyrene resist, or an imide resist is formed on the substrate 111 so as to cover the above-described elements and wirings. And a pixel electrode (diffuse reflection electrode) 120 made of a metal material having high reflectivity such as Al or Ag is formed as a reflection layer on the organic insulating layer 119.
[0046]
A plurality of pixel electrodes 120 are formed in a matrix on the organic insulating layer 119. In the present embodiment, one pixel electrode 120 is provided corresponding to a region defined by the scanning lines 126 and the signal lines 125. The pixel electrode 120 is disposed such that its edges are along the scanning lines 126 and the signal lines 125, and substantially all regions of the substrate 111 except for the TFT 130, the scanning lines 126, and the signal lines 125 are defined as pixel regions. It is supposed to.
[0047]
The organic insulating layer 119 is patterned into a substantially circular or substantially elliptical shape in plan view, as shown in FIG. 10, and each of the patterned resin layers 119 is processed into a curved surface shape as shown in FIG. ing. That is, the organic insulating layer 119 functions as the above-mentioned convex portion, and the organic insulating layer 119 and the pixel electrode 120 as a reflective layer laminated thereon form the reflector 1 of the present invention. Note that, as shown in FIG. 10, the organic insulating layer 119 is arranged so as not to extend over a plurality of pixel regions, so that signal leakage does not occur between pixels.
[0048]
Further, contact holes 121 and 122 leading to the drain electrode 117 are formed in the organic insulating layer 119, and are formed on the organic insulating layer 119 via conductive portions 120 a formed in the contact holes 121 and 122. The pixel electrode 120 thus formed is electrically connected to the drain electrode 117 provided below the insulating layer. In this configuration, reliable conduction between the pixel electrode 120 and the TFT 130 is obtained through the two contact holes 121 and 122. However, one or three or more such contact holes may be provided. .
[0049]
On the substrate 111 configured as described above, an alignment film 123 made of polyimide or the like that has been subjected to a predetermined alignment process such as rubbing so as to cover the pixel electrode 120 and the organic insulating layer 119 is further formed. I have.
[0050]
On the other hand, the opposing substrate 140 is configured as a color filter array substrate, and a color filter layer 142 as shown in FIG. 9 is formed on a transparent substrate main body 141 made of glass, plastic, or the like.
[0051]
As shown in FIG. 12, in the color filter layer 142, color filters 142R, 142G, and 142B that respectively transmit light of red (R), green (G), and blue (B) wavelengths are periodically arranged. Each of the color filters 142R, 142G, and 142B is provided at a position facing each pixel electrode 120. In the color filter layer 142, a light-shielding layer 142S is formed in a region where the color filters 142R, 142G, and 142B are not formed.
[0052]
On the color filter layer 142, a transparent counter electrode (common electrode) 143 such as ITO or IZO is formed, and a predetermined alignment process is performed on at least a position of the substrate 140 corresponding to the display area. An alignment film 144 made of polyimide or the like is formed.
[0053]
The substrates 110 and 140 configured as described above are held in a state where they are fixedly separated from each other by a spacer (not shown), and a thermosetting seal applied in a rectangular frame shape around the substrate. It is adhered by a material (not shown). Then, the liquid crystal is sealed in a space sealed by the substrates 110 and 140 and the sealant to form a liquid crystal layer 150 as a light modulating layer, and the liquid crystal panel 100 is formed.
[0054]
As shown in FIG. 8, the front light 200 has a flat light guide 220 made of a transparent member such as an acrylic resin and provided on the liquid crystal panel 100, and is disposed on a side end surface of the light guide 220. A rectangular prism-shaped intermediate light guide 212 made of a transparent member such as an acrylic resin, and a light emitting element 211 such as an LED (Light Emitting Diode) disposed on one end surface of the intermediate light guide 212 in the longitudinal direction. It is configured with.
[0055]
The intermediate light guide 212 is disposed substantially parallel to the light guide 220 via an air layer, and totally reflects light that is shallowly incident on a boundary surface between the air layer and the light guide 212 to form the light guide 212. Propagate inside. In addition, a wedge-shaped groove (not shown) is formed on a surface of the light guide 212 opposite to the light guide 220 in order to emit light propagated in the light guide 212 toward the light guide 220. A metal thin film with high light reflectivity such as Al or Ag is formed in the groove.
[0056]
The light guide 220 is disposed substantially parallel to the display surface of the liquid crystal panel 100 via the air layer, and a side end surface facing the intermediate light guide 212 is a light incident surface 220a and faces the liquid crystal panel 100. The surface (lower surface) is configured as a light emission surface 220b. In order to make the light incident from the incident surface 220a fall toward the emission surface 220b, a prism-shaped groove 221 is formed on the upper surface of the light guide 220 (the surface opposite to the liquid crystal panel 100). Is formed.
[0057]
As shown in FIG. 11, the groove 221 has a wedge shape including a pair of slopes 221a and 221b, and the angle θ of the gentle slope 221a with respect to the reference plane N. ₁ Is set in a range of, for example, 1 ° or more and 10 ° or less. This is, for example, the angle θ ₁ Is less than 1 °, the average brightness of the front light 200 decreases, and θ ₁ Is larger than 10 °, the output light amount becomes non-uniform in the output surface 220b. The angle θ of the steep slope 221b with respect to the reference plane N ₂ Is set in the range of, for example, 41 ° or more and 45 ° or less, so that the deviation between the propagation direction of the light reflected by the steep slope 221b and the normal direction of the emission surface 220b is reduced.
[0058]
Further, the width of the steep slope 221b of the groove 221 (the width in the direction perpendicular to the extending direction of the groove 221) is configured to be wider as the groove 221 is farther from the incident surface 220a, and the incident surface where the light amount is apt to decrease. The amount of emitted light at a position distant from 22a increases. As a specific example, when the width of the steep slope 221b of the groove 221 located closest to the incident surface 220a is 1.0, the light guide that is farthest from the incident surface 220a (that is, the light guide facing the incident surface 220a). The width of the steep slope 221b of the groove 221 (in the vicinity of the end face of the body 220) is 1.1 to 1.5.
[0059]
Further, as shown in FIG. 12, the extending direction of the groove 221 is inclined by a predetermined angle α with respect to the arrangement direction (x-axis direction) of the pixels 120A of the liquid crystal panel. Moire is prevented from occurring. This inclination angle α is configured to be in a range of more than 0 ° and 15 ° or less, and it is desirable to be 6.5 ° or more and 8.5 ° or less. Also, the pitch P of the groove 221 ₁ Is the pixel pitch P ₀ Is smaller than the pitch P of the groove 221. ₁ The illumination unevenness having a period of? Is leveled in the pixel 120A, and is not recognized by the observer. In particular, the pitch P of the groove 221 ₁ And pixel pitch P ₀ And 0.5P ₀ <P ₁ <0.75P ₀ It is desirable to configure so as to satisfy the following relationship.
[0060]
As shown in FIGS. 8 and 11, the intermediate light guide 212 and the light guide 220 are formed by a case-shaped casing 213 having a metal thin film 213a of high reflectivity such as Al or Ag formed on the inner surface. It is preferable that they are fixed integrally.
Therefore, according to the liquid crystal display device of the present embodiment, since the reflector 1 including the organic insulating layer 119 and the pixel electrode 120 is provided on the active matrix substrate, it is bright in a specific observation direction and has a wide viewing angle. A wide display can be obtained.
[0061]
[First Modification]
Next, a first modified example of the present invention will be described with reference to FIGS. FIG. 13 is a diagram showing a convex portion constituting the reflector according to the present modification, and FIG. 14 is a diagram showing its reflection characteristics.
[0062]
In this modification, the surface shape of the convex portion 119 shown in FIG. 2 is modified to change the directivity of the reflector.
Similar to the convex portion 119 of the above embodiment, the main convex portion 119 'is composed of a first curved surface having a small curvature and a second curved surface having a large curvature, and the first curved surface and the second curved surface are respectively shown in FIG. In the X-section shown, a first curve A 'extending from one peripheral portion S1 of the convex portion 119' to the top portion D, and the other peripheral portion extending smoothly from the top portion D of the convex portion 119 'to the first curve A'. It has a shape indicated by a second curve B 'reaching S2.
[0063]
The top D is located at a position shifted in the x direction from the center O of the projection 119 ′, and the average of the absolute values of the inclination angles of the first curve A ′ and the second curve B ′ with respect to the substrate surface S is They are set irregularly in the respective ranges of 2 ° to 90 ° and 1 ° to 89 °, and the average value of the inclination angle of the first curve A ′ is larger than that of the second curve B ′. . In addition, the inclination angle δa in the peripheral portion S1 of the first curve A ′ indicating the maximum inclination angle is irregularly varied in each convex portion 119 ′ within a range of approximately 4 ° to 35 °. Thus, the height d of each convex portion 119 'is irregularly varied within the range of 0.25 to 3 [mu] m.
[0064]
On the other hand, each of the first curved surface and the second curved surface has a substantially left-right symmetrical shape with respect to the center O in the Y section shown in FIG. The shape of this Y section is a curve E having a large curvature (that is, a gentle curve close to a straight line) around the top D, and the absolute value of the inclination angle with respect to the substrate surface S is configured to be approximately 10 ° or less. I have. Further, the absolute values of the inclination angles of the deep curves F and G with respect to the substrate surface S are irregularly varied within a range of, for example, 2 ° to 9 °. Further, the height d of the top D is irregularly varied within a range of 0.1 μm to 3 μm.
[0065]
FIG. 14 is a diagram showing the reflection characteristics of the reflector composed of the above-mentioned convex portions 119 ′. The substrate surface S is irradiated with external light from the x-direction side at an incident angle of 30 ° to change the viewing angle. The light receiving angle θ when the light is swung from a position of 0 ° (perpendicular line position) to a position of 60 ° with respect to the normal direction of the substrate surface S around the position of 30 ° which is the direction of regular reflection with respect to the substrate surface S, The relationship with brightness (reflectance) is shown. In FIG. 14, for the sake of comparison, the relationship between the light receiving angle and the reflectance (see FIG. 3) of the reflector 1 of the above embodiment is also indicated by a dotted line.
[0066]
In the reflector of this modified example, the reflectance at around 20 ° is smaller, but the reflectance at around 30 °, which is specular reflection, is higher than that of the embodiment shown by the dotted line. I understand. That is, similarly to the above embodiment, since the top D of the convex portion 119 'is shifted from the center O of the convex portion 119' toward the y direction, the reflectance on the low angle side is higher than the regular reflection angle of 30 °. Also, since the vicinity of the top D of the convex portion 119 'is a gentle curved surface, the reflectance in the regular reflection direction is also increased.
The other configuration is the same as that of the above embodiment, and the description thereof is omitted.
[0067]
Therefore, in this modified example, the same effect as in the above-described embodiment can be obtained, and when a reflector is formed by the convex portion 119 ', a display with high reflection luminance in the regular reflection direction can be obtained.
[0068]
[Second embodiment]
Next, a method for manufacturing a reflector according to the second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be partially omitted.
[0069]
In the manufacturing method of the reflector according to the present embodiment, the protrusion 520 is formed on the substrate 510 made of glass or the like by the same method as the method of manufacturing the protrusion 119 of the first embodiment shown in FIGS. Then, a reflector forming matrix 500 is manufactured. Then, as shown in FIG. 15A, the matrix 500 is housed and placed in a box-shaped container 600, and a resin material 601 having good releasability, such as silicone, is poured into the container 600, left at room temperature, and cured. Let it. Then, the cured resin product is taken out of the container 600, unnecessary portions are cut off, and a transfer mold 700 having a large number of concave portions 700a having concave and convex shapes opposite to a large number of convex portions 520 forming the mold surface of the matrix 500 is formed. It is manufactured (see FIG. 15B). Instead of the above-described method, the transfer mold 700 may be manufactured by copying the uneven shape of the projection 520 by electroless plating or the like.
[0070]
Next, as shown in FIG. 15B, a positive photosensitive resin 190 such as an acrylic resist, an azide resist, an epoxy resist, a polystyrene resist, or an imide resist is formed on a transparent substrate 111 such as glass. Is applied by a coating method such as a spin coating method, a screen printing method, and a spraying method, and the photosensitive resin 190 on the substrate 111 is prebaked using a heating device such as a heating furnace or a hot plate.
[0071]
Next, as shown in FIG. 15C, the mold surface 700a of the transfer mold 700 is pressed against the photosensitive resin 190 for a certain time to transfer the mold surface 700a to the photosensitive resin 190. Then, a light beam 701 such as ultraviolet rays (g, h, i rays) for curing the photosensitive resin 190 is irradiated from the back surface side of the transparent substrate 111 to cure the photosensitive resin 190. The photosensitive resin 190 is peeled off.
[0072]
Next, the photosensitive resin 190 on the substrate 111 is post-baked and baked using a heating device such as a heating furnace or a hot plate. As a result, a projection 119 '' having the same shape as the projection 520 of the matrix 500 is formed on the surface of the photosensitive resin 190 (see FIG. 15D).
[0073]
Finally, a reflective layer 120 made of a metal film having a high reflectivity such as Al or Ag is formed on the surface of the photosensitive resin 190 having the convex portion 119 '' by a sputtering method, a CVD method, an ion beam method, or the like. , Reflector 1 'is completed.
[0074]
Therefore, according to the reflector manufacturing method of the present embodiment, the projections formed by the manufacturing method of the above-described first embodiment are used as the reflector forming matrix 500, and the transfer mold 700 is manufactured from the matrix 500. Further, since the transfer mold 700 is pressed against the resin 190 on the substrate 111 to form the convex portion 119 ″ on the resin 190, the convex portion 119 ″ is manufactured by the manufacturing method of the first embodiment. The shape can be substantially the same as the convex portion 520 of the mother die 500. Therefore, when the reflector 1 ′ is formed by the convex portion 119 ″, external light can be effectively used by the directivity, and a display with a wide viewing angle can be obtained.
[0075]
In addition, since the protrusions having the same shape can be manufactured only by pressing the transfer mold against the photosensitive resin 190 and curing the same, the manufacturing time can be significantly reduced, and waste of members and the like can be reduced. Therefore, the manufacturing cost can be significantly reduced.
[0076]
Note that the present invention is not limited to the above-described embodiment, and can be implemented with various modifications without departing from the spirit of the present invention.
For example, the above-described TFT 130 is not limited to the inverted staggered structure, and may be a normal staggered TFT. The switching element is not limited to a TFT, and may be a diode having an MIM (Metal Insulator Metal) structure in which an insulating layer is interposed between metal layers. Further, the liquid crystal panel 100 may be a so-called simple matrix type TN type or STN type liquid crystal panel.
[0077]
The substrate on which the color filter layer 142 is formed is not limited to the counter substrate 140 side, and the color filter layer 142 may be provided on the active matrix substrate 110 side. Accordingly, the light-shielding layer 142S is formed on either the active matrix substrate 110 or the counter substrate 140. Of course, the color filters 142R, 142G, 142B and the light shielding layer 142S may be provided on different substrates. Further, the color filter can be omitted to display in black and white.
[0078]
In the above embodiment, the reflection type liquid crystal display device is described. For example, in the above-described configuration, a backlight is arranged on the back side of the active matrix substrate 110, and an opening (opening ratio) is formed in the center of the pixel electrode 120. (About 10% to 30% with respect to the pixel area) can be a so-called transflective liquid crystal device.
[0079]
【The invention's effect】
As described in detail above, according to the present invention, a convex section obtained by patterning a photosensitive resin is irradiated with an etching material from an oblique direction, so that the convex section has a specific cross section perpendicular to the substrate. Can be processed into an asymmetric shape. In particular, by adjusting the irradiation angle and irradiation amount of the etching material to control the surface shape of the projection, the directivity of the reflector obtained by forming the reflection layer on the projection can be freely designed.
Further, since the diameter of the projections when viewed in plan is configured to be random within the substrate surface, the inclination angle of the surface of the projections with respect to the substrate surface after the surface processing step is irregularly varied within the substrate surface. And a display with a wide viewing angle can be obtained.
Further, since such a surface shape is controlled by photolithography technology, a reflector having a desired shape can be easily manufactured even when the substrate size of the liquid crystal display device is relatively large. .
[Brief description of the drawings]
FIGS. 1A and 1B are diagrams showing a schematic configuration of a reflector according to a first embodiment of the present invention, wherein FIG. 1A is a plan view thereof, and FIG.
FIGS. 2A and 2B are schematic diagrams showing a configuration of a convex portion of a reflector according to the first embodiment of the present invention, wherein FIG. 2A is a perspective view, FIG. ) Is the Y sectional view.
FIG. 3 is a diagram showing reflection characteristics of a convex portion of the reflector according to the first embodiment of the present invention.
FIG. 4 is a process chart for explaining a method of manufacturing the reflector according to the first embodiment of the present invention.
FIG. 5 is a process chart for explaining a method of manufacturing the reflector according to the first embodiment of the present invention.
FIG. 6 is a process chart for explaining a method of manufacturing the reflector according to the first embodiment of the present invention.
FIG. 7 is an enlarged view of a main part showing a configuration of a photomask used in a manufacturing process of the reflector according to the first embodiment of the present invention.
FIG. 8 is a perspective view illustrating an overall configuration of the liquid crystal display device according to the first embodiment of the present invention.
FIG. 9 is a cross-sectional view illustrating an entire configuration of a liquid crystal panel included in the liquid crystal display device according to the first embodiment of the present invention.
FIG. 10 is a plan view illustrating the entire configuration of a liquid crystal panel included in the liquid crystal display device according to the first embodiment of the present invention.
FIG. 11 is a partial cross-sectional view of a front light included in the liquid crystal display device according to the first embodiment of the present invention.
FIG. 12 is a plan view of a liquid crystal panel included in the liquid crystal display device according to the first embodiment of the present invention, illustrating a state in which a counter substrate is viewed from a front light side.
FIGS. 13A and 13B are schematic views showing a configuration of a convex portion of a reflector according to a first modification of the present invention, wherein FIG. 13A is a perspective view thereof, FIG. ) Is the Y sectional view.
FIG. 14 is a diagram showing reflection characteristics of a convex portion of a reflector according to a first modification of the present invention.
FIG. 15 is a process chart for explaining a method of manufacturing a reflector according to the second embodiment of the present invention.
FIG. 16 is a process chart for explaining a conventional method for manufacturing a reflector.
FIG. 17 is a process chart for describing a conventional reflector manufacturing method.
[Explanation of symbols]
1 Reflector
111 substrate
119 convex
120 reflective layer
190 Photosensitive resin layer
300 Photomask
400 Reactive etching gas (or electron beam)
T1-T7 pattern

Claims (6)

A resin layer forming step of forming a photosensitive resin layer on the substrate,
A patterning step of exposing and developing the photosensitive resin layer through a photomask on which a plurality of predetermined patterns are formed, and patterning a convex portion made of the photosensitive resin on the substrate in plan view;
In a coordinate system in which the normal direction of the substrate is the Z-axis direction, a surface processing that irradiates or sprays an etching material on the surface of the substrate from a direction forming a predetermined angle with respect to the Z-axis to process the surface of the convex portion. Process and
Forming a reflective layer on the surface of the substrate having the convex portions formed thereon. A resin layer forming step of forming a photosensitive resin layer on the base material,
A patterning step of exposing and developing the photosensitive resin layer through a photomask on which a plurality of predetermined patterns are formed, and patterning a convex portion made of the photosensitive resin on the base material in plan view;
In a coordinate system in which the normal direction of the base material is the Z-axis direction, the surface of the base material is processed by irradiating or spraying an etching material on the surface of the base material from a direction forming a predetermined angle with respect to the Z axis. Surface processing step,
A step of forming a transfer mold by molding a concave and convex shape of the surface of the base material formed by the convex portion,
A resin layer forming step of forming a photosensitive resin layer on the substrate,
Transferring the uneven shape of the surface of the transfer mold to the resin layer,
Forming a reflective layer on the surface of the substrate on which the irregularities have been transferred. The pattern of the photomask used in the patterning step has a substantially circular or substantially elliptical shape,
The method for manufacturing a reflector according to claim 1, wherein the diameter of the pattern and the interval between adjacent patterns are configured at random. In the patterning step, the photosensitive resin layer is exposed to light through a photomask whose light transmittance is adjusted for each pattern, and the resistance to the etching material is adjusted for each convex portion. Item 5. The method for producing a reflector according to any one of Items 1 to 3. 5. The method according to claim 1, wherein, in the surface processing step, the etching material is irradiated while rotating the irradiation angle in the azimuth direction in a predetermined angle range while keeping the irradiation angle in the polar angle constant. A method for producing a reflector according to any one of the above items. A liquid crystal display device comprising a reflector manufactured by the method for manufacturing a reflector according to claim 1.

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