JP2015038573A - Optical device, and manufacturing method of optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical device that can be more easily manufactured and uses an electrowetting effect.SOLUTION: A liquid crystal optical element includes first and second substrates that are arranged opposite to each other, a frame-like partition member that is held by the first and second substrates, and a liquid member that is charged in a closed space defined by the partition member, and contains a first solvent containing at least water, a second solvent having hydrophobicity, and surfactant distributed at the boundary between the first and second solvents.

Description

  The present invention relates to an optical device using an electrowetting effect and a manufacturing method thereof.

  Optical elements (EW elements) utilizing the electrowetting (EW) effect are disclosed in, for example, Patent Documents 1 and 2. The EW element mainly includes a pair of substrates disposed opposite to each other, and a partition wall sandwiched between the pair of substrates and having a shape surrounding a predetermined region when viewed from the normal direction of the pair of substrates. And a liquid member containing a polar solvent and a nonpolar solvent that are filled in a closed space defined by the pair of substrates and the partition walls and are incompatible with each other.

  In general, an EW element is manufactured by dropping a polar solvent and a nonpolar solvent onto one of a pair of substrates, and then bonding the pair of substrates together. In order to manufacture the EW element, at least a step of dropping a polar solvent and a step of dropping a nonpolar solvent onto one of the pair of substrates are required.

Special table 2007-531917 gazette JP 2012-230175 A

  The main object of the present invention is to more easily manufacture an optical device using the electrowetting effect.

  According to an aspect of the present invention, the first and second substrates are arranged to face each other, and the first substrate is provided on the surface close to the second substrate with a gap between each other. The first and second electrodes, and a smooth layer covering the first and second electrodes and having water repellency and electrical insulation properties, the second substrate being on a surface close to the first substrate The first and second substrates including the third electrode provided opposite to the first and second electrodes, and the first and second substrates, the first and second substrates being sandwiched between the first and second substrates, A partition member that surrounds a region where the first and second electrodes and the third electrode overlap when viewed from the normal direction of the second substrate, and defines the pixel region; And a first solvent containing at least water and sparsely filled in a closed space defined by the partition member. A second solvent having a gender, and an optical device and a liquid member containing a surface active agent distributed on the interface of the first and second solvent, are provided.

  According to another aspect of the present invention, a) first and second electrodes provided on the surface with a gap therebetween, and the first and second electrodes are covered with water repellency and electrical insulation. A first substrate having a first region having a first region extending over the first and second electrodes, and a third electrode formed on a surface of the first substrate, including the third electrode. A step of preparing a second substrate having a second region opposite to the first region when bonded to the first substrate; and b) a partition member that is a surface of the first substrate. Forming the first region of the substrate or forming the second region on the surface of the second substrate, and c) a first solvent containing at least water, hydrophobic A liquid member mixed with a second solvent having a surfactant and a surfactant is applied to the first region of the surface of the first substrate. Or dropping onto the second region of the second substrate surface; and d) bonding the first and second substrates so that the first and second regions face each other. A step of bonding the liquid member so that the liquid member is enclosed in a closed space defined by the first and second substrates and the partition member. Is provided.

  An optical device using the electrowetting effect can be obtained more easily.

1A and 1B are a cross-sectional view and a plan view showing a basic structure of an EW element according to the embodiment, and FIG. 1C is a cross-sectional view showing another structure of the EW element according to the embodiment. FIG. 2A is a flowchart showing a manufacturing process of the EW element according to the embodiment, and FIGS. 2B and 2C are photographs showing the liquid member used in the liquid member dropping process. 3A and 3B are cross-sectional views illustrating a state in which the EW element according to the embodiment is driven. 4A to 4C are plan views showing other structures of the EW element according to the embodiment.

  Hereinafter, the structure, manufacturing method, and driving method of the EW element 1 according to the embodiment of the present invention will be described with reference to FIGS. In addition, the relative size of each component shown in the drawing is different from the actual one.

  1A and 1B are a cross-sectional view and a plan view schematically showing a basic structure of the EW element 1. The IA-IA cross section in FIG. 1B corresponds to the cross sectional view shown in FIG. 1A. In FIG. 1B, some components (the light shielding layer 23, the liquid member 40, etc.) are omitted for convenience.

  The EW element 1 mainly includes a lower substrate 10, an upper substrate 20, a partition member 30, and a liquid member 40.

  As shown in FIG. 1A, the lower substrate 10 includes first and second lower electrodes 12 and 13 provided on the surface of the lower base substrate 11 with a gap therebetween, and first and second lower electrodes. 12 and 13 and a smooth layer 14 having water repellency and electrical insulation. A light reflecting plate 15 may be provided on the back surface of the lower base substrate 11. As shown in FIG. 1B, the first and second lower electrodes 12 and 13 are formed, for example, in a stripe shape.

  As the lower base substrate 11, for example, a blue plate or a white plate glass substrate can be used. For the first and second lower electrodes 12 and 13, for example, an indium tin oxide (ITO) film or the like can be used. For the smooth layer 14, for example, a Teflon (registered trademark) film or the like can be used.

  As shown in FIG. 1A, the upper substrate 20 is disposed to face the lower substrate 10, and the upper electrode 22 provided on the surface of the upper base substrate 21 and the light shielding formed on a part of the surface of the upper electrode 22. And a layer 23. The light shielding layer 23 is generally provided in a region facing the second lower electrode 13 of the lower substrate 10. The light shielding layer 23 may be provided on the back surface of the upper base substrate 21.

  As the upper base substrate 21, for example, a blue plate or a white plate glass substrate can be used. For the upper electrode 22, for example, an ITO film can be used. For the light shielding layer 23, for example, an aluminum layer or a molybdenum layer can be used.

  The partition member 30 is sandwiched between the lower and upper substrates 10 and 20 as shown in FIG. 1A. Moreover, as shown to FIG. 1B, it has the frame shape surrounding the area | region where the 1st and 2nd lower side electrodes 12 and 13 and the upper side electrode 22 overlap. For the partition member 30, for example, an ultraviolet curable resin is used.

  Here, a space defined by the lower and upper substrates 10 and 20 and the partition member 30 is referred to as a closed space 51. Further, in plan view, a region where the first and second lower electrodes 12 and 13 and the upper electrode 22 overlap and is surrounded by the partition member 30 is referred to as a pixel region 52.

  As shown in FIG. 1A, the liquid member 40 is filled in a closed space 51, and includes a first solvent 41 containing at least water and a hydrophobic second phase that is phase-separated from the first solvent 41. A surfactant distributed at the interface between the solvent 42 and the first and second solvents 41 and 42 is included. The first and second solvents 41 and 42 are not mixed with each other and are unevenly distributed in the closed space 51. Since the smooth layer 14 has water repellency, the first solvent 41 is usually positioned away from the smooth layer 14, and the second solvent 42 is positioned in contact with the smooth layer 14.

  Pure water is suitably used for the first solvent 41. As the second solvent 42, for example, oil mainly composed of petroleum is used. Note that a dye (pigment) may be dissolved in the first or second solvent 41, 42. The surfactant may be any one that can emulsify the first and second solvents 41 and 42.

  FIG. 1C is a cross-sectional view showing another configuration of the liquid member 40. When the surfactant is added in a relatively large amount in the liquid member 40, the second solvent 42 is in a form in which a plurality of granular droplets are clustered. Even in such a case, the first and second solvents 41 and 42 are unevenly distributed in the closed space 51.

  FIG. 2A is a flowchart showing a manufacturing process of the EW element 1. Hereinafter, a method for manufacturing the EW element 1 will be described with reference to FIG. 2A with reference to FIGS. 1A to 1C.

  First, two glass substrates with ITO electrodes are prepared. The thickness of the ITO electrode is about 80 nm, and the thickness of the glass substrate is about 0.7 mmt. One glass substrate corresponds to the lower base substrate 11, and the other glass substrate corresponds to the upper base substrate 21.

  The lower substrate 10 is produced (step S101).

  An ITO electrode formed on the surface of one glass substrate (lower base substrate 11) is formed (patterned) into a stripe shape by an etching method using a mask or the like. As a result, the first and second lower electrodes 12 and 13 are formed on the surface of the lower base substrate 11 so as to be spaced from each other.

  Subsequently, a Teflon (registered trademark) material (manufactured by DuPont) is applied and heat-treated so as to cover the first and second lower electrodes 12 and 13. For application of the Teflon (registered trademark) material, for example, a spin coating method or the like can be used. Thereby, the smooth layer 14 covering the first and second lower electrodes 12 and 13 is formed. The smooth layer 14 may have a laminated structure in which an insulating layer having electrical insulating properties and a water-repellent layer having water repellency are laminated, and the insulating layer covering the first and second lower electrodes 12 and 13 may be used. After the formation, a water repellent layer may be formed on the surface of the insulating layer.

  Thus, the lower substrate 10 is completed.

  The upper substrate 20 is produced (step S102).

  An ITO electrode (upper electrode 22) is formed on the surface of the other glass substrate (upper base substrate 21). If necessary, the upper electrode 22 is patterned into a desired planar shape by an etching method, a laser ablation method, or the like. An aluminum film or a molybdenum film is formed on a part of the surface of the upper electrode 22 to form a light shielding layer 23. An insulating layer may be formed on the upper electrode 22 surface or the light shielding layer 23 surface. The insulating layer can be formed of, for example, polyimide.

  Thus, the upper electrode 20 is completed.

  The partition member 30 is formed on one of the manufactured lower and upper substrates 10 and 20, for example, the upper substrate 20 (step S103). A photocurable resin (positive photosensitive resist) is applied so as to cover the upper electrode 22 and the light shielding layer 23. For the application of the photocurable resin, for example, a spin coating method or the like can be used. Thereafter, the photocurable resin is exposed to light using a mask having a predetermined light-shielding pattern, and further developed. Thereby, the partition member 30 is formed on the surface of the upper substrate 20.

  The liquid member 40 is dropped onto one of the manufactured lower and upper substrates 10 and 20, for example, the lower substrate 10 using a dispenser, a micropipette, or the like (step S104). In the example, the liquid member 40 was prepared by mixing and stirring pure water (first solvent 41), oil (second solvent 42), and a surfactant. In the examples, oil (second solvent 42) in which black dye was dissolved was used. The surfactant is preferably added at a ratio of 0.01 to 1.0 Vol% with respect to pure water (first solvent) and oil (second solvent).

  The upper substrate 20 on which the partition member 30 is formed is bonded to the lower substrate 10 onto which the liquid member 40 has been dropped (step S105). At this time, the lower and upper substrates 10 and 20 are bonded so that the liquid member 40 is accommodated in the space (closed space 51) surrounded by the lower and upper substrates 10 and 20 and the partition member 30. Is done. Further, in a plan view, the first and second lower electrodes 12 and 13 and the upper electrode 22 are bonded to each other, and the second lower electrode 13 and the light shielding layer 23 are bonded to each other. Thereafter, a sealing member is attached to the side end surfaces of the bonded lower and upper substrates 10 and 20 or an adhesive is applied to fix the relative positional relationship between the lower and upper substrates 10 and 20. In addition, the overflow of the liquid member 40 is suppressed. Thereby, the EW element 1 is completed. In the embodiment, the light reflecting plate 15 is disposed on the back surface of the lower substrate 10.

  2B and 2C are photographs showing the liquid member used in the liquid member dropping step (step S104). FIG. 2B shows the liquid member in the stirring state, and FIG. 2C shows the liquid member in the stable state. In addition, the liquid member in a stable state shall mean the liquid member after leaving the liquid member in a stirring state for 5 minutes or more stably. The liquid member shown in the photo is a mixture of 1 ml of pure water (first solvent), 2 ml of oil (second solvent), and 6 μl of surfactant, and is contained in a test vial. ing.

  From the photograph shown in FIG. 2B, it can be seen that the liquid member in the stirring state is entirely black. That is, it can be seen that the oil (second solvent) in which the black dye is dissolved is uniformly dispersed in colorless and transparent pure water (first solvent) by stirring.

  From the photograph shown in FIG. 2C, it can be seen that the liquid member in the stable state is separated into a black region (upper side in the small bottle) and a transparent region (lower side in the small bottle). That is, it can be seen that colorless and transparent pure water (first solvent) and oil in which black dye is dissolved (second solvent) are unevenly distributed in the small bottle.

  In the liquid member dropping step (step S104), when a liquid member in which the surfactant is not mixed and the first and second solvents are completely phase-separated, a desired amount and one In the process, it is difficult to drop the first and second solvents onto the substrate. Therefore, it is necessary to divide the liquid member dropping step (step S104) into two steps, that is, a step of dropping a desired amount of the first solvent onto the substrate and a step of dropping a desired amount of the second solvent onto the substrate. There is.

  On the other hand, in the liquid member dropping step (step S104), when a liquid member (liquid member in a stirring state) in which the surfactant is mixed and the first and second solvents are stirred is used. Since the second solvent is uniformly dispersed in the first solvent, the first and second solvents can be dropped onto the substrate in a desired amount and in one step. The liquid member is allowed to stand after the substrate bonding step (step S105), whereby the first and second solvents are separated in the state shown in FIGS. 1A to 1C, that is, in the closed space ( (The liquid member in a stable state).

  When the amounts of pure water (first solvent), oil (second solvent), and surfactant are about 1 ml, 2 ml, and 6 μl, respectively, 1C, that is, a form in which a large number of granular droplets are gathered. For example, when the amount of pure water (first solvent), oil (second solvent), and surfactant is about 1 ml, 2 ml, and 2 μl, respectively, The oil has a form shown in FIG. 1A, that is, a form constituted by a single droplet.

  3A and 3B are cross-sectional views showing how the EW element 1 is driven. FIG. 3A shows the state of the first and second solvents 41 and 42 when a voltage is applied between the first lower electrode 12 and the upper electrode 22, and FIG. The state of the first and second solvents 41 and 42 when a voltage is applied to the upper electrode 22 is shown. For the power source 60 connected to the first and second lower electrodes 12, 13 and the upper electrode 22, for example, a power source capable of outputting an alternating voltage (amplitude 10V to 20V, frequency 10kHz to 1MHz) is used. it can.

  As shown in FIG. 3A, when a power source 60 is connected between the first lower electrode 12 and the upper electrode 22 and an AC voltage is applied, the first solvent 41 (pure water) is converted into the first lower electrode. 12 Move so as to be drawn upward. At this time, light incident from the upper substrate 20 side passes through the first solvent 41 (pure water) that is colorless and transparent, is reflected by the light reflecting plate 15, and is emitted from the upper substrate 20 side again. That is, a bright state is realized in an area where the light shielding layer 23 of the pixel area 52 is not disposed. Thereby, the bright display of the EW element 1 is realized. In addition, the area | region where the light shielding layer 23 of the pixel area 52 is arrange | positioned is always a dark state.

  As shown in FIG. 3B, when the power source 60 is connected between the second lower electrode 13 and the upper electrode 22 and an AC voltage is applied, the first solvent 41 (pure water) becomes the second lower electrode. 13 Move so as to be drawn upward. Light incident from the upper substrate 20 is absorbed by the second solvent 42 (oil) in which the black dye is dissolved. That is, a dark state is realized in a region of the pixel region 52 where the light shielding layer 23 is not disposed. Thereby, dark display of the EW element 1 is realized. In addition, the area | region where the light shielding layer 23 of the pixel area 52 is arrange | positioned is always a dark state.

  In this way, by controlling the voltage applied between the first lower electrode 12 and the upper electrode 22 or between the second lower electrode 13 and the upper electrode 22, The dark display can be switched (switched). Such an EW element 1 could be applied to a display element, for example. Further, if the light reflection plate 15 is not provided, it may be used as an optical shutter element, for example.

  Further investigations by the present inventors show that when a surfactant is mixed in the first and second solvents 41 and 42 and the applied voltage is a DC voltage, It is known that the movement of one solvent 41 becomes dull, that is, the response speed becomes slow. Further, it is known that when the pixel region 52 is larger than 500 μm on a side, the response speed of the first solvent 41 becomes slow.

  Further, when the second solvent 42 is in the form shown in FIG. 1A, that is, in the form constituted by a single droplet, the first solvent 41 is decreased as the frequency of the applied AC voltage is lowered. It is known that the response speed of will be faster. On the other hand, when the second solvent 42 is in the form shown in FIG. 1C, that is, in a form in which a large number of droplets are clustered, the response of the first solvent 41 increases as the frequency of the applied AC voltage increases. I know the speed will be faster.

  4A to 4C are plan views showing other shapes of the partition member 30 or the lower electrodes 12 and 13 in the EW element 1. The planar shape of the partition member 30 or the lower electrodes 12 and 13 can be easily adjusted by changing the mask pattern used in the partition member forming step (step S103) or the lower substrate manufacturing step (step S101). Is possible.

  As shown in FIG. 4A, the EW element 1 may further include a partition member 31 that is formed integrally with the partition member 30 and includes a gate portion 31a. By providing such a partition member 31, the EW element 1 can be provided with a memory property.

  The partition member 31 divides the closed space 51 into two spaces, that is, first and second spaces 51a and 51b. The first space 51 a is mainly defined above the first lower electrode 12, and the second space 51 b is mainly defined above the second lower electrode 13. When an AC voltage is applied between the first or second lower electrode 12, 13 and the upper electrode 22, the first and second solvents 41, 42 filled in the closed space 51 become the gate portion of the partition member 31. It is possible to travel between the first and second spaces 51a and 51b through 31a.

  For example, when a voltage is applied between the first lower electrode 12 and the upper electrode 22, the first solvent 41 is attracted to the upper side of the first lower electrode 12, that is, moves to the first space 51a. Then, when the application of the voltage is stopped, a part of the first solvent 41 moves to the second space 51b and tries to restore the steady state (the state shown in FIGS. 1A to 1C). However, at this time, if the partition member 31 is provided, the movement of the first solvent 41 to the second space 51b is restricted, and the first solvent 41 remains in the first space 51a.

  Thus, by providing the partition member 31, the first solvent 41 (or the second solvent 42) is kept in the space previously occupied, that is, the previous arrangement state of the first solvent 41 is maintained. It becomes possible. For this reason, the EW element 1 has a memory property.

  When the partition member 31 is provided, as shown in FIG. 4B, in the region corresponding to the gate part 31a of the partition member 31, the first lower electrode 12 projects to the second space 51b side (projected part 12a), It is preferable that the second lower electrode 13 projects to the first space 51a side (projected portion 13a). Thus, when a voltage is applied between the first or second lower electrode 12, 13 and the upper electrode 22, the movement of the first solvent 41 to the first or second space 51 a, 51 b is prevented. Become smooth.

  The partition member 31 may not be provided so as to equally divide the closed space 51. For example, as shown in FIG. 4C, the closed space 51 is divided into a first space 51 a that defines an approximately 1/4 space of the closed space 51, and an approximately 3/4 space of the closed space 51. It may be provided so as to be divided into the second space 51b. At this time, it is preferable that the first lower electrode 12 is provided so as to correspond to the first space 51a, and the second lower electrode 13 is provided so as to correspond to the second space 51b.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not restrict | limited to these. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF SYMBOLS 1 ... Electrowetting element (EW element), 10 ... Lower substrate, 11 ... Lower base substrate, 12 ... 1st lower electrode, 13 ... 2nd lower electrode, 14 ... Smooth layer, 15 ... Light reflecting plate 20 ... upper substrate, 21 ... upper base substrate, 22 ... upper electrode, 23 ... light shielding layer, 30 ... partition member, 31 ... partition member, 40 ... liquid member, 41 ... first solvent, 42 ... second solvent , 51 ... pixel area, 52 ... closed space, 60 ... AC power supply.

Claims (10)

First and second substrates disposed opposite to each other, wherein the first substrate is provided on the surface close to the second substrate with a gap between each other; and A smooth layer covering the first and second electrodes and having water repellency and electrical insulation, and the second substrate is disposed on a surface close to the first substrate. The first and second substrates, including a third electrode provided opposite to
A region sandwiched between the first and second substrates and where the first and second electrodes and the third electrode overlap when viewed from the normal direction of the first and second substrates. A partition member that surrounds and defines a pixel region;
A first solvent containing at least water, a second solvent having hydrophobicity, and the first and second filling the enclosed space defined by the first and second substrates and the partition member; A liquid member containing a surfactant distributed at the solvent interface;
An optical device comprising:   The optical apparatus according to claim 1, wherein the liquid member has a form in which the first and second solvents are unevenly distributed in the closed space.   The optical device according to claim 2, wherein the second solvent has a form in which a plurality of granular droplets are gathered.   Furthermore, the power supply which can apply an alternating voltage between the said 1st and 3rd electrode and between the said 2nd and 3rd electrode, respectively is provided, The power supply which can be respectively provided. The optical device described. And a partition member including a gate portion that divides the closed space into a first space and a second space, and is capable of traveling between the first space and the second space,
When viewed from the normal direction of the first and second substrates,
The first space is mainly defined in a region corresponding to the first electrode;
The second space is mainly defined in a region corresponding to the second electrode.
The optical device according to claim 1. In a region corresponding to the gate portion of the partition member when viewed from the normal direction of the first and second substrates,
The first electrode protrudes to the second space side,
The second electrode protrudes toward the first space;
The optical device according to claim 5.   The optical device according to claim 1, wherein the pixel region has a rectangular shape with a side of 500 μm or less. a) First and second electrodes provided on the surface with a gap between each other, and a smooth layer having water repellency and electrical insulation properties, covering the first and second electrodes, A first substrate having a first region straddling the first and second electrodes, and a third electrode formed on the surface, including the third electrode, and bonded to the first substrate A step of preparing a second substrate having a second region opposite to the first region;
b) forming the partition member so as to surround the first region on the surface of the first substrate, or forming the partition member so as to surround the second region on the surface of the second substrate;
c) dropping a liquid member in which the first solvent containing at least water, the second solvent having hydrophobicity, and the surfactant are mixed into the first region of the first substrate surface; or Dropping onto a second region of the second substrate surface;
d) a step of bonding the first and second substrates so that the first and second regions face each other, wherein the liquid member includes the first and second substrates, and Bonding to be enclosed in the enclosed space defined by the partition member;
A method for manufacturing an optical device.   9. The method of manufacturing an optical device according to claim 8, wherein, in the step c), the liquid member has a form in which the second solvent is uniformly dispersed in the first solvent.   The method of manufacturing an optical device according to claim 9, wherein after the step d), the liquid member is configured such that the first and second solvents are unevenly distributed in the closed space.