TW200929603A - Method and structure for controlling surface curvature of droplets - Google Patents

Abstract

The invention related to a method and structure for controlling surface curvature of droplets, in which the surface curvature control is realized by a number of multistage structures on a substrate. By the depth variation of stages formed in each multistage structure as well as the hydrophobic surface of each stage, the moving direction of a droplet dripping thereon as well as the surface curvature of the droplet can be controlled in a manner that the droplet is formed conforming to a predefined shape.

Description

200929603 IX. Description of the Invention: [Technical Field] The present invention relates to a structure and method for controlling the curvature of a liquid bead, in particular to controlling the curvature of a bead surface by a multi-order or gray-scale structure, including a multi-step Or a composite micro/nano structural substrate of gray scale. The multi-order or gray-scale structure of the control surface bead curvature may be a combination of depth, jump height change, composite level multi-order or gray scale, etc., wherein the structure height of each area is different: the device utilizes each area Different structures are arranged in height to achieve control of the surface curvature of the bead. [Prior Art] Environmental protection issues and energy crisis are the two most important issues in the 21st century. ^Diode (LED) light source not only has a long life span (4), it also has the characteristics of no pollution, and the color, emission rate and heat dissipation technology. The upgrade is applied to various light source products in life. earth

. 1 (D) Chlp itself is a point light source without w. In some applications, the light field distribution of the demand is special (for example, it needs to be done by secondary optical modulation. Usually the distribution of the light field in the second. But the special light field distribution Often accompanied by: easy to install the shape of the rim, plus the coffee product is not a spherical overall size = size must be allowed (at least _ system, grade), which is quite difficult to form in the production of j nano, etc. in the drop into the LED ehip It can quickly and accurately locate the packaging material 50,000' and naturally 200929603 « • The shape of the lens (LENS) is the design of the special package shape curvature is the direction of this patent creation research. See the US patent number: The method of "Method and apparatus for n〇n-contact electrostatic actuation of droplets" is disclosed in the specification of an apparatus for driving an electrode: comprising a first conductive layer (220) and a second conductive layer ( 4)), an extension element (132), the first conductive layer (220) comprising a substrate such as glass (222), a conductor layer such as ITO (223), an insulating layer (226) and a water repellent layer on the conductor layer (224). And Ο The second conductive layer (40) comprises a hydrophilic surface and faces the surface of the first water repellent layer (224), and the potential difference is between the two conductive layers (40) and the elongating member (132), so that the electrostatic effect can drive the liquid Bead advancement. However, the disadvantage is that it is necessary to apply voltage to the electrode to achieve the purpose. For another known technique, please refer to the patent name of US Patent No.: US 2007/0047388: "Fluidic mixing structure, method for fabricating same, and mixing method Wherein the patent discloses a micromixer for providing a fluid comprising a plurality of bead input tubes for communicating with a mixer cavity. The mixer cavity comprises a surface pattern such as a pyramid microstructure (84). 'To define the respective areas of fluid repellency and hydrophilicity, different beads will flow from the input tube to the output tube and mix the beads for identification analysis. However, the purpose is to transport different kinds of liquid beads, as disclosed in this case. The technical field is different. For further art, please refer to the patent name of US Pat. No. 5,871,888: "Method of forming multiple-layer microlenses and use """" reveals the reflow technique of forming microlenses, first depositing two transparent layers; the first layer is a columnar photoresist layer, the second layer is a photoresist layer of lens 200929603. There is a cylindrical structure on the rf layer. As a mask, the cross section is equal to or smaller than the cross section of the cylindrical structure. Into (four) engraved FKUG (four). Lu Weiwei post north became fkuh. This technique ^

The microlens has a firm curvature and a large numerical aperture. The disadvantage of being fine is that the curvature error of the control lens is better than that of the above-mentioned prior art, which is developed by utilizing the hydrophilicity and water repellency of the substrate. However, in the field of LEN^, the patents have not been proposed, and the field of the light-emitting diode is a major breakthrough. [Disclosed from the above] The main purpose of the present invention is to propose a special kind of multi-order or gray-scale microstructure on the surface of the wafer in the first optical packaging of the brain. When the package is made of an unhardened polymer material, the liquid bead material can rapidly roll directly above the LED chip and form a predetermined curvature shape, thereby achieving the predetermined shape. The special light field distribution. For the above purpose, the invention has a control surface bead curvature (four) structure, which is formed on the substrate to form a plurality of multi-order structures; wherein the depression depth of the multi-stage structure is changed And a hydrophobic surface for controlling the surface curvature of the bead and the direction of movement of the bead to achieve a predetermined shape. Further explanation of the present invention is further illustrated by the following figures, drawings and inventions. It is helpful for your review committee to review the work. 7 200929603 . [Embodiment] The detailed structure of the present invention and its connection relationship are explained in conjunction with the following drawings. In the middle of a detailed explanation, said, in order to facilitate your understanding of the commission. Please also refer to Figure A A D and Figure 2, which follows the definition of contact angle in Martin Stelzleetal. [l]: for stationary liquid beads 〇2 In contact with the surface of solid 01, the contact angle of liquid bead 02 with the surface of solid 01 can be obtained by the formula of Thomas Young (1805): O c〇s^c -γ8Ι)/γ,

Young's Formula where γ is the surface tension between the two phases, S solid '1' is the liquid, and & is the contact angle of the solid surface with the liquid surface, as shown in Figure 2. When A <90. The surface has a hydrophilic character, and when 6>> 90°, the surface has a water-repellent property, as shown in Fig. 1d. This formula is derived from the force balance point of view and is suitable for smooth homogenizing solid 〇1 surface. Figure A above shows that 6 and 〇 (乂 is close to zero); Figure 1 B is revealed as 〇 < 4 < 45 °; Figure 1 C is disclosed as 45. $纥$90. Figure 1 D is revealed as ❹ 6^90°. Therefore, the liquid bead 02 shown in Figure 1a to Figure D is hydrophilic, with Figure A being the largest; and Figure 1D being the smallest. The relationship between the contact interface between the liquid bead and the air is calculated by 'Laplace-Young equation[2]: A Κ2 In the above formula, 4 is the radius of curvature of a point on the surface of the bead, and μ is the pressure of the inside and the outside. Poor, η is the surface tension of the liquid bead. If the liquid bead and the water repellency are strong, the difference between the pressure on the air and the part of the repellent water is 2, and the surface is continuous (four) crane. That is, the liquid bead on the surface will spontaneously move from a strong water repellency to a weaker water repellency. ❹ ❹ We can know from Laplace.Young equati〇n that the characteristics of the liquid bead and surface energy can be changed by surface microstructure. In this way, not only can the flow direction of the bead be controlled, i can be changed. The contact angle between the bead and the surface naturally forms a special curvature shape. Furthermore, according to the application technology developed by the Lotus effect, academic research and product development on hydrophobic surfaces have been booming in recent years. Therefore, we know that the hydrophobic design of the water-repellent surface can change the hydrophilic and hydrophobic properties between the liquid droplets on the surface and the surface. In theory, this method can not only control the flow behavior of the liquid bead, but also change the liquid bead and The contact angle between the surfaces naturally produces a special aspherical curvature of the bead shape. Please refer to FIG. 3, which is a package structure diagram of a single-chip light-emitting diode. The package of the light-emitting diode (LED) is usually a single or multiple LED indium gallium nitride power semiconductor wafers (InGaN P〇). The wer chip 13 is attached to the heat sink 12 by a solder or an adhesive, and a substrate is formed under the heat sink 12 and formed over the indium gallium nitride power wafer 13 . A transparent epoxy resin 14 encapsulating material, which can be considered as a primary lens 'again covering a lens (LENS) (the lens 16 can be regarded as a secondary lens)' is assembled into an LED light source. Since the LED chip itself is almost uniformly illuminated 9 200929603 . = point source, in order to make it easier to achieve the required light field distribution on the secondary optical package, plus the size of the LED package size The package size must be miniaturized. We break through the traditional LED diode encapsulation technology and control, and the curvature of the primary optics can be thinned. At the same time, the polymer bead can be controlled (this embodiment is transparent). The resin or polymer material) can be quickly and accurately positioned above the indium gallium nitride power wafer 13 when it is dropped into the light-emitting diode indium gallium nitride power chip 13 to form a primary lens so as not to cause alignment errors. The distribution of the light field is inaccurate. The following describes a technique for controlling the curvature of the surface of the liquid bead. At the same time, the distribution state of the light field of the light-emitting diode can be precisely controlled to achieve good illumination. Therefore, in this case, a special multi-order or gray-scale microstructure is formed on the surface of the wafer by using a light-emitting diode in a single optical package, and the unhardened polymer transparent liquid droplet is dropped into the light-emitting diode by a special microstructure designed. On the surface of the packaged component, its liquid droplets can quickly roll over the LED array and naturally form the curvature of the lens to be designed, so that we can easily achieve the special light field distribution we designed. Please refer to FIG. 4, which is a side view of the gray-scale structure of the preferred embodiment and a corresponding side view of the gray-scale structure, wherein a plurality of gray-scale structures are formed on a substrate 2. The gray-scale structure is a smooth continuous and linear change from the center to the outer side, and from the outer side to the middle part of the hollow. The depth of the recess of the gray-scale structure changes (the familiar art can also use the gray-scale structure) Designed as a protruding structure), in the embodiment, the first gray scale structure 21 at the center is shallow, and the third gray scale structure 23 near the two sides in the middle is deep, and of course, it is familiar with the technique. Shi can also design the gray-scale structure to be deeper at the center and shallower on the two sides to achieve the liquid 200929603 ❹

The purpose of the bead flow is also within the scope of the present invention. It is used to control the surface bead curvature of the bead and the movement of the bead (please refer to Figure 12 to achieve the predetermined shape, and the bead is a transparent tree or a polymer material, and the SMb can be formed after forming) The lens (that is, the "once, mirror" of the transparent epoxy resin 14 formed on the indium gallium nitride power chip 13 as shown in FIG. 3 above), and the substrate 2 has a long thin appearance, which can be regarded as a long rectangle. The bottom substrate of the indium gallium power chip 13 is disordered. According to the different appearance of the gallium nitride gallium power chip 13 substrate, it can be considered that the circular shape and the rectangular shape are the protection scope of the invention. The deeper depth of the step structure moves to the shallower depth region. In this implementation, the left and right sides are at the center, and the movement is as shown in Fig. 12. The liquid bead is because of the hydrophobic surface ( Or the repulsion depth of the repulsion and the gray-scale structure produces different shapes (eg, = f - A to Figure 1D). The substrate can be an organic material, a glass genus, a germanium wafer, or a compound semiconductor material. Constructed, the surface of the substrate is hydrophobic (4) Similarly, the influence on the flow of the bead 10 is also different. The shape of the gray-scale structure is a rectangle, an arch, a triangle a (not shown), a rectangle (not shown) or any shape (not shown) The structure can be cracked by hot pressing, injection, laser or any chemical or physical method. Please refer to FIG. 5 as a top view of the multi-stage structure of the substrate of the invention and a comparison of the side view. The preferred embodiment is similar to the fourth embodiment in that the first multi-stage structure 31 at the center of the substrate 3 is shallow, the second multi-stage structure between the towels is 32 times, and the third side is close to the two sides. The multi-order structure % is deeper, and the difference from Fig. 4 is that the multi-step structure depth is not continuous linear representation, but for the jump 200929603, the degree of change 'the continent's p# structure can also be the effect of the drainage liquid shown in Figure 4. Please refer to FIG. 6 , which is a plan view of a top view and a cross-sectional side view of a gray scale structure of the substrate of the present invention. The gray scale structure is continuous compared with the foregoing FIG. 4 . Smoothing the structure, and forming a first gray scale structure 41 and a second gray scale junction on the substrate 4 42 and the third gray-scale structure 43, the state of the adjacent gray-scale structure without any interruption can also achieve the result shown in Fig. 4. The material shown in Fig. 7 is a multi-stage structure of the substrate of the invention. Another preferred embodiment of the top view and the cross-sectional side view, the multi-step structure is similar to the above-mentioned FIG. 5, and is also a skipped multi-stage structure, and a first gray-scale structure 51 is formed on the substrate 5, The second gray-scale structure 52 and the third gray-scale structure", but the state between the adjacent multi-order structures 4 has any interruption state, and can also achieve the effect as shown in Fig. 5. Please refer to FIG. A preferred embodiment of a plan view and a cross-sectional side view of the annular gray scale structure, and the substrate has a circular shape, which is formed once above the circular LED indium gallium nitride power wafer. The lens can be formed into a circular lens, and the circular light-emitting diode is widely used. Therefore, the following figures are mostly descriptions of the multi-step or gray-scale structure of the circular substrate. The structure of FIG. 8 is similar to that of FIG. 4, only the shape of the substrate of FIG. 4 is changed to a circular shape, and the multi-step or gray-scale structure is changed to an arch shape, and the remaining structures can perform the same functions as those of FIG. a first gray scale structure 61, a second gray scale structure 62 and a third gray scale structure 63 are formed on the material 6, and the liquid droplets 1〇 move from a deep depth region of the gray scale structure to a shallow depth region. In this embodiment, it is moved from the outer side of the circle to the center of the circle, that is, as shown in FIG. 13 12 200929603. The structure of the substrate is similar to that of the substrate of the invention, and the structure of the figure is shown in the figure of Fig. 9 and the structure of Fig. 9 is changed to a circular shape and a multi-order or gray The order junction (4) m π @ is formed with the first multi-order structure 7 and the second and second gray-scale structure 73, and the functions of the remaining structures are all the same as those of the figure = so they are not described here.

夕π,目: See the figure 10 is a diagram of another preferred embodiment of the substrate of the invention forming an annular gray-scale structure in the (four) side view, the structure of Figure 10 and the figure ', only ' In order to change the shape of the substrate of FIG. 6 to a structure, the shape of the first gray scale structure 82 and the second gray scale structure 83 'the remaining structure can be formed on the substrate 8 ', The same, it is not described here, the liquid bead 10 moves from the shallower region of the deeper depth m of the gray-scale structure. In the present embodiment, I7 is moved from the outer side to the center of the circle, that is, as shown in FIG. The disclosure of the four. Referring to FIG. 11 , it is a top view and a cross-sectional side view of the substrate of the present invention. The structure of FIG. 11 is similar to that of FIG. The shape of the substrate is changed to a circular shape, and the multi-step or gray-scale structure is changed into an arch shape, and the first multi-step structure 91, the second multi-step structure 92, and the third multi-order structure are formed on the substrate 9, and the rest The functions that the structure can play are the same as those in Figure 7, and we will not go into details here. Please also refer to FIG. 15A, B, C and ϋ, which are experimental diagrams showing the difference in radius of curvature of the hydrophilic surface of the present invention, wherein the substrate for the pattern experiments is a silicon wafer (Silic). 〇n Wafer), the liquid bead carried on the substrate is UV glue (adhesive 13 which is solidified after irradiation with ultraviolet rays). In F15B, the contact angle of the substrate with the liquid bead (Contact Angle) It is 2〇.86. The radius distance (Radius) formed is 5.3798 mm; in the needle C, the contact angle of the substrate with the liquid bead (c〇福(4) is 22.40., and the radius distance (Radius) formed is 5. 6_; In Figure 15D, 'the contact angle of the substrate to the bead (Contact Α_) is 22.56' and the half-control distance (secret) formed is 4. 727_; the liquid data from the above data can be understood The hydrophilicity of the beads is related to the radius of curvature

Even the sound of the contact is small (4), the diameter of the curve (4) will be larger (compared with the following figure κ, Β), and the hydrophilicity of the nasal bead and the substrate can achieve a predetermined contact. angle. Please also refer to _16Α, Β, which is the experimental diagram of the difference in radius of curvature of the water-repellent surface of the present invention, wherein the pattern of the experiment is based on a substrate (Nickel) The liquid droplets carried are also υν glue. In Figure 16 , the contact angle of the substrate to the bead is 5 (U) 3 ° ' * The radius distance (Radius) formed is 1.54287 mm; from the above data, the liquid can be understood. The water repellency of the beads is related to the radius of curvature. The radius of curvature caused by the larger contact angle of I* is smaller (compared with Fig. 15B, c, d), and the liquid bead and substrate are calculated. The water repellency can achieve a predetermined contact angle. b, as shown in FIG. 17, is a schematic diagram of the invention for controlling the curvature of a surface by using a width and depth material. The substrate is designed to have four base wafers for the experiment. In the stepped structure, the liquid bead carried by the base 10 is water. The lateral width of each step is 2/1 and the longitudinal depth is 3.6/zm. The deepest position of the step is set to the first degree, and the second depth is the second. Contact angle; again deep third contact angle; 200929603 The southernmost position is the fourth contact angle, and the experimental data is as follows: For the eighteenth A to the figure, please refer to Figure 18A to Figure 18, where the data of Figure 18 is 10/m in width and the depth is 3.6" soft 3==1〇8. The contact angle is 132. 22°; Figure 18B reveals that the environmental data is also ^, the longitudinal depth is 3.6//mx2=7.2, and its contact = 130.19. The environmental data disclosed in Figure 18C is also the width 1〇"m, vertical= The depth is 3.6/zmxl = 3.6#111, and the contact angle is 129.4. Figure 18: The exposed environmental data is also the width, the longitudinal depth is 3 6/zmx() = ()# m' and the contact angle is Π1. 31 °. From the above data, it can be understood that the change in depth caused by the gray-scale or step-like structure can indeed change the contact angle of the liquid bead. The deeper the depth of the structure, the larger the contact angle, and the case can be proved by the ash. Step or stepped structure to control the radius of curvature of the bead is indeed feasible. In addition, the pattern of Figure 15A to Figure 16B reveals that the hydrophilicity and water repellency of the surface of the substrate can also control the radius of curvature of the bead and Contact angle. By the two conditions of structural depth change and water repellency on the surface of the substrate, it is indeed possible to achieve the case. The function of the above. It can be understood from the above disclosure of FIG. 1A to FIG. 18D that the present invention proposes an innovative technique for controlling the curvature of the bead surface of the bead, which is specially made on the surface near the wafer during the LED-sub-optical packaging. The multi-step or gray-scale microstructure, by the special microstructure of the design, when the package is filled with the unhardened polymer transparent liquid bead material, the liquid bead material can be quickly rolled into the light-emitting diode chip (LED) The chip is directly above and naturally forms a predetermined curvature shape, thereby achieving a predetermined special light field distribution. In the future, the size of the light-emitting diode is in the millimeter size, and it has great practicality, so a patent application is filed to seek 15 200929603 patent. In view of the above, the structural features and embodiments of the present invention have been disclosed in detail, and the present invention can be fully demonstrated that the purpose and efficacy of the present invention are deep and rich, and the industrial use value is extremely valuable. And for the unprecedented use on the market, according to the spirit of the patent law, the present invention fully meets the requirements of the invention patent. The preferred embodiment of the present invention is not limited to the scope of the present invention, that is, the equivalent variation and modification of the patent in accordance with the present invention should still fall within the scope of the invention. I would like to ask your review board member to abide by, and pray for the best. It is a simple explanation of the drawing. Figure 1A is the first schematic diagram of the contact between the liquid bead and the solid surface; Figure 1B is the second contact between the liquid bead and the solid surface. Schematic diagram; • Figure 1C is the third schematic diagram of the liquid bead contacting the solid surface; Figure 1D is the fourth schematic diagram of the solid surface contact of the liquid bead; Figure 1 is a schematic diagram of the contact angle of the hydrophobic surface liquid bead; The second embodiment is a package structure diagram of a single-wafer light-emitting diode; FIG. 4 is a top view and a cross-sectional side view of a substrate for forming a gray-scale structure of the present invention; FIG. 6 is a plan view showing a gray-scale structure of a substrate of the present invention, and a cross-sectional side view of another preferred embodiment; FIG. Multi-layer structure FIG. 8 is a plan view showing a ring-shaped gray scale structure of the substrate of the present invention, and a cross-sectional side view of the substrate of the present invention; FIG. 9 is a substrate formation of the present invention. A preferred embodiment of a plan view and a cross-sectional side view of a ring-shaped multi-stage structure; FIG. 10 is a view of another preferred embodiment of the substrate of the present invention forming an annular gray-scale junction and a cross-sectional side view; FIG. 12 is a perspective view of another preferred embodiment of the substrate of the present invention. FIG. 12 is a perspective view of FIG. 4 and FIG. 13 is a perspective view of FIG. Fig. 15 is a schematic view showing the difference in radius of curvature of the hydrophilic surface of the present invention; ❹ Figure 15B is an experimental diagram showing the difference in radius of curvature of the hydrophilic surface of the present invention; The fifth C is the experimental diagram of the difference in the radius of curvature of the hydrophilic surface of the present invention; and FIG. 15D is the third experimental diagram of the difference in the radius of curvature of the hydrophilic surface of the present invention; Invention on water repellency The experiment is not intended to cause the difference in radius of curvature; Figure 16B is the first experimental diagram of the difference in radius of curvature of the water-repellent surface of the present invention; 17 200929603 Lin (four) step structure to control curvature ΐ; The surface of the bead formed by a contact angle is shown in Fig. 18 as a schematic diagram of the curvature; the surface of the bead formed by the second contact angle of Fig. 17

Figure 18 is a schematic diagram of the use of curvature; Figure 18 is a schematic diagram of the use of curvature. The surface of the bead formed by the third contact angle of Fig. 17 is the surface of the bead formed by the fourth contact angle of Fig. 17.匕: r symbol description] 02 ~ liquid bead 1 〇 ~ liquid bead Q 11 ~ substrate 12 ~ heat sink 3 ~ indium gallium nitride power wafer 14 ~ epoxy resin 16 ~ lens 2, 3 21 4, 5, 6, 7 41, 61 S, 9 to the substrate 29 81 to the first gray scale structure 42 62, 82 to the second gray scale structure 3l, s 63 83 to the second gray scale structure, 71, 91 to the first multistage structure 200929603 32, 52, 72, 92~ second multi-order structure 33, 53, 73, 93~ third multi-order structure

19

Claims (1)

200929603 X. The scope of the patent application·· 1 R^ has a method for controlling the curvature of the liquid bead of the surface, which is a structure on the substrate, a plurality of ecliptic structures; wherein the depth of the depression and the hydrophobic surface by the multi-order structure It is used to control the curvature of the surface of the bead and the direction of movement of the bead to achieve a predetermined shape. 1 = ❹ G, which has the curvature of the control surface bead as described in Item 1 of the patent scope, wherein the substrate and the structure after the bead is cured are lenses applied to the light-emitting diode. In the case of Fang Jie, which has the control surface bead curvature as described in the Chinese Patent No. 1_1, the substrate is composed of an organic material, a glass, a metal, a tantalum wafer or a compound semiconductor material. The shape of the rectangular or / or any step structure having the control surface bead curvature described in Item 1 of the above paragraph 15 is a rectangle, a 郷, a triangle, and a singularity of the control 1 The depth of the hop type is changed to 6. As stated in the patent scope, the size of the multi-stage structure is a curvature or a micro/nano structure. , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , The area with a deeper white ice is deeper. 8. As claimed in the patent application method, the structure of the Μ 阶 structure with the control surface bead curvature described in dr item can be controlled by hot pressing, injection, laser or 200929603 arbitrarily chemical or Physical method production. I. The method of controlling the surface bead curvature described in Item 1 wherein the liquid bead is a transparent tree, wherein the adjacent multi-order structure is A method of controlling the curvature of a surface bead, which is formed on a substrate and is: ΓΓΤ ΓΓΤ 其 其 其 其 其 其 其 其 其 其 其 其 凹陷 凹陷 凹陷 凹陷 凹陷 凹陷 凹陷 凹陷 凹陷 凹陷 凹陷 凹陷 凹陷The surface curvature of the bead and the movement of the liquid bead have a structure which controls the surface liquid bead curvature and the light-emitting diode liquid is trapped. The structure is applied as described in item n of the patent application: 丄f The material is composed of organic materials, broken glass, gold: sheet or compound semiconductor materials. The method of controlling the curvature of a surface bead as described in claim 11 wherein the shape of the gray-scale structure is a rectangle, an arch, a _^ shape, a rectangle or an arbitrary shape. - The angle of the control has the control surface liquid bead curvature. The depth variation of the structure of the 灰 灰 灰 ρ is a flat culture, in which the structural depth of each area is different. Ice 16. The method of controlling the surface bead curvature described in claim 11 of the Patent Application No. 11 Jf 200929603 17: The liquid bead is moved from the shallower region of the structure to the mildew. The area of the wood is in the depth of the nth item having a control surface bead curvature n, wherein the gray level structure can be produced by thermal refractory, injection = or chemical or physical methods. 'The control surface surface bead curvature as described in item u. 20. For example, (Shen) (4)" / green bead is a transparent resin or polymer material. The control surface liquid described in item U of the U range The shape of the bead curvature is interrupted or uninterrupted between the adjacent gray-scale structures twenty two