KR101175929B1 - Variable liquid lens - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable focus fluid lens using electro wettiong, and more particularly to a first fluid and a second fluid contacting on a meniscus in an eye-shaped manner. The variable focus fluid lens, which is composed of a variable focus fluid lens, can be easily changed in focus even at a low voltage, can be easily provided with two electrodes on the same plane, and can be easily sealed to suppress bubble generation inside the lens. The present invention relates to a transparent substrate, a dielectric thin film deposited on an upper surface of the transparent substrate, and a first fluid and a second fluid that do not mix with each other at different refractive indices on the top of the dielectric thin film and are in contact with a meniscus (M). A polymer film sealed in a substantially hemispherical state with a fluid filled therein, and a first electrode and the second fluid insulated from the second fluid by the dielectric thin film. The fluid provides a variable focus lens which comprises a second electrode which is provided so as to.

Description

Variable focus lens

The present invention relates to a variable focus fluid lens using electrowetting, and more particularly to a first fluid and a second fluid contacted on a meniscus in an eye-shaped manner. The variable focus fluid lens, which is composed of a variable focus fluid lens, can be easily changed in focus even at a low voltage, can be easily provided with two electrodes on the same plane, and can be easily sealed to suppress bubble generation inside the lens. It is about.

Generally, a camera has a plurality of lenses and is configured to adjust the optical focal length by moving each lens to change its relative distance. On the other hand, as optical devices such as a camera on which such a lens is mounted are miniaturized, the lens is also required to be miniaturized.

A method for meeting the miniaturization requirement is a variable focus lens as disclosed in PCT International Publication No. WO 03/069380.

1 is a simplified cross-sectional view of a variable focus proposed as an embodiment of WO 03/069380. As shown in FIG. 1, the variable focus lens has a non-mixable first fluid A and a second fluid B which have different refractive indices and are contacted through a meniscus 14. Having a cylindrical fluid chamber 5, a fluid contact layer 10 disposed inside the cylinder wall, and the first fluid A and the second fluid by the fluid contact layer 10. A first electrode 2 separated from B) and a second electrode 12 for activating the second fluid B are included.

Here, the first electrode 2 is cylindrical and coated by an insulating layer 8 and made of a metallic material, and the second electrode 12 is disposed on one side of the fluid chamber 5. . In addition, the transparent front element 4 and the transparent rear element 6 form a cover of the fluid chamber 5 containing the two fluids.

On the other hand, reference numeral 16 of FIG. 4 is a seal for sealingly coupling the front element 4 and the fluid contact layer 10.

The operation of the variable focus lens having such a configuration is as follows.

When no voltage is applied between the first electrode 2 and the second electrode 12, the fluid contact layer has a higher wettability with respect to the first fluid A than the second fluid B. . If a voltage is applied between the first and second electrodes, wettability due to the second fluid B is changed due to electrowetting, and the contact angle Q1 of the meniscus 14 is shown as shown. Q2 and Q3) change.

Accordingly, the shape of the meniscus is changed according to the applied voltage, and focus control is performed using the meniscus.

That is, the angle between the meniscus 14 and the fluid contact layer 10 measured in the first fluid (A) according to the magnitude of the voltage applied as shown in FIGS. Approximately 140 °, 100 °, 60 ° and so on.

Here, FIG. 1 shows an arrangement having a high negative power, FIG. 2 a low negative power, and FIG. 3 a positive power.

As such, the variable focus lens using the fluid is advantageous in miniaturization compared to the method of adjusting the focus through the mechanical driving of the conventional lens.

However, such a variable focus lens has disadvantages as shown in FIG. 4. That is, since the variable focus lens is made of liquid, bubbles 18 may be generated as shown in FIG. 4 if it is not properly sealed in the chamber 5.

In order to prevent this, there is a method of performing the lens assembly operation in the liquid, but this does not completely suppress the generation of bubbles, deteriorates workability and prevents mass production of the lens. In the prior art, there is a difficulty in packaging the fluid, and there is a disadvantage in that the packaging is carried out individually.

Accordingly, the present invention is to solve the above problems and to provide a variable focal fluid lens using a polymer film that wraps in a substantially hemispherical shape with the first and second fluids filled inside on a flat transparent substrate instead of a chamber. An object of the present invention is to provide a variable focus fluid lens that prevents performance degradation due to bubble generation inside a chamber, which is indicated as a conventional problem by providing a fluid lens in an eye shape.

In addition, it is possible to provide a variable focus fluid lens on the planar transparent substrate to provide a variable focus fluid lens that can be easily adjusted at low voltage.

In addition, in the present invention, it is possible to configure a planar electrode that allows two electrodes to be provided together on the upper side of the transparent substrate, which is composed of a conventional side electrode and a bottom electrode, so that an electric signal is easily applied and packaging (packaging). To be very advantageous.

Furthermore, the fluid is packaged through polymer encapsulation, so that mass production is possible by polymer coating several devices at the same time.

The present invention provides a variable focus fluid lens using electrowetting, comprising: a transparent substrate 110; a dielectric thin film 120 deposited on an upper surface of the transparent substrate 110; and a top of the dielectric thin film 120. A polymer film 130 which is not mixed with each other with different refractive indices and is sealed in a substantially hemispherical state in which the first fluid A and the second fluid B contacting the meniscus M are filled; And a first electrode 140 insulated from the second fluid B by the dielectric thin film 120; and a second electrode 150 provided to act on the second fluid B. It provides a variable focus fluid lens configured.

Here, the first electrode 140 and the second electrode 150 are characterized in that they are provided side by side on the top plane of the transparent substrate 110.

In addition, the hydrophobic thin film is provided between the dielectric thin film 120 and the first and second fluids (A) and (B).

In addition, a hydrophilic thin film 170 and a hydrophobic thin film 160 are provided between the dielectric thin film 120 and the first and second fluids A and B, wherein the second fluid B is a central portion of the fluid lens. It is located on the upper surface of the hydrophilic thin film 170 is provided in a substantially circular shape around the center, the first fluid (A) is located on the upper surface of the hydrophobic thin film 160 provided in a ring shape on the outside of the hydrophilic thin film 170 It features.

In addition, the first fluid (A) is a non-conductive fluid, the second fluid (B) is characterized in that the conductive fluid.

In addition, the density difference between the first fluid (A) and the second fluid (B) is characterized in that within 30%.

In addition, the hydrophobic thin film is characterized in that the fluoropolymer (fluoropolymer).

In addition, the polymer film 130 is characterized in that using parylene (parylene).

In addition, the first fluid (A) is characterized in that using any one of mineral oil, silicone oil, sunflower oil, hexadecane (hexadecane).

In addition, the dielectric thin film 120 is characterized in that using parylene (parylene).

In addition, the first electrode 140 is characterized in that the contact with the first fluid (A).

Using the present invention,

First, since the eye-shaped variable focus fluid lens composed of a polymer film surrounding the transparent substrate can be provided, the overall volume of the lens can be reduced, thereby miniaturizing the lens.

Second, by the deposition technology of the polymer film surrounding the first and the second fluid placed on the transparent substrate in a state filled inside, it is possible to prevent the performance degradation due to the internal bubble generation of the lens.

Third, since the internal bubble generation problem, which has been a problem in the prior art, is solved, the lens can be mass-produced by polymer encapsulation at room temperature at low vacuum, and thus, the manufacturing can be easily performed, thereby greatly improving productivity.

Fourth, since the electrowetting effect is shown directly on the planar substrate, efficient focusing is possible even at low voltage.

1 to 3 are cross-sectional views showing the structure and operation of a variable focus lens according to the prior art,
4 is a cross-sectional view showing a problem of a variable focus lens according to the prior art,
5 to 7 are cross-sectional views schematically showing a configuration of a variable focus fluid lens according to an exemplary embodiment of the present invention.
8A to 8F are views showing an example of a manufacturing process of a variable focus fluid lens according to an exemplary embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in this specification and claims should not be construed in a common or dictionary sense, and the inventors will be required to properly define the concepts of terms in order to best describe their invention. Based on the principle that it can, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, at the time of the present application, It should be understood that there may be water and variations.

5 to 7 are cross-sectional views schematically illustrating a configuration of a variable focus fluid lens according to an exemplary embodiment of the present invention.

As shown in FIGS. 5 to 7, the present invention relates to a variable focus fluid lens using electrowetting, and typically deposits a dielectric thin film 120 on an upper surface of a transparent substrate 110 made of glass. And a hydrophobic first fluid (A) and a hydrophilic second fluid (B), which are not mixed with each other, are sealed in a substantially hemisphere in a separated state while contacting a phase with a meniscus (M). And a second electrode 150 provided to act on the first electrode 140 and the second fluid B insulated from the second fluid B by the dielectric thin film 120. Also includes.

The transparent substrate 110 may be the basis on which the variable focus fluid lens of the present invention is manufactured, and a transparent glass material is mainly used to facilitate light transmission.

The dielectric thin film 120 is deposited on the upper surface of the transparent substrate 110, which not only functions as an insulating layer but also seals the bubbles inside the fluid lens together with the polymer film 130. Will also do. The dielectric thin film 120 preferably uses parylene to perform this role.

In the present embodiment, the two fluids (A) and (B) may include a hydrophobic non-conductive first fluid (A), such as silicon or alkane, also referred to as 'oil', and a salt solution. It consists of two immiscible liquids in the form of a hydrophilic conductive second fluid (B), such as water. They are sealed by the polymer film 130 to form a substantially hemispherical shape in contact with the meniscus (M).

These two fluids are preferably configured to have the same density (specific gravity), wherein the lens functions not depending on the orientation, i.e. without depending on the gravitational effect between the two liquids. This may be accomplished by the selection of an appropriate first fluid component. That is, for example, alkanes or silicone oils may be modified by addition of molecular components to increase their density in order to match the density of the salt solution. However, it is not essential that the density be the same, and if the density difference between the two fluids is about 30% or less, the present invention can be utilized.

Depending on the choice of oil used, the refractive index of the oil may vary between 1.25 and 1.60. Similarly, depending on the amount of salt added, the salt solution may be changed between 1.33 and 1.48 in refractive index. However, the present invention is not limited thereto, and the present invention may be utilized by various modifications.

Here, the first fluid (A) may be any one of mineral oil, silicone oil, sunflower oil, hexadecane, and the second fluid (B) is potassium chloride (KCL), sodium chloride (NACL) ), Glycerin, and the like or mixtures thereof (eg, a mixture of KCL: glycerin = 1: 0.3) may be used as the conductive fluid, and these may be variously applied depending on the application.

The polymer film 130 fills and seals the first and second fluids A and B disposed on the transparent substrate 110 to provide an appearance of an eye-shaped variable focus fluid lens. The final forming configuration should be a transparent material, it is preferable to use parylene (parylene).

The polymer film 130 is heated to a high temperature in a low vacuum (10mTorr ~ 100mTorr) to form a fine particle and then conformally deposited while cooling at room temperature low vacuum (10mTorr ~ 100mTorr). Conformal deposition (conformal) is possible to coat with a uniform thickness and coating at low vacuum also does not enter the bubble. For reference, the equipment to be used in the present invention is called a lab coater (lab coater) product type is PDS2010.

The first electrode 140 is preferably formed of a metal material, and is provided in a state insulated from the second fluid B by the dielectric thin film 120. That is, the dielectric thin film is coated with an insulating layer formed of parylene, which is a material provided with the dielectric thin film. The thickness of the insulating layer is between 50 nm and 100 μm, and typical values are between 1 μm and 10 μm. In addition, the second electrode 150 is preferably provided in contact with the second fluid (B) to act on the second fluid (B). In addition, the first and second electrodes 140 and 150 are preferably formed of a metal material, and an ITO electrode may be used. In addition, the first electrode 140 and the second electrode 150 may be provided side by side on the top surface of the transparent substrate 110, so that the connection of the electrodes is convenient, easy to use, and very simple to manufacture. Can be.

The insulating layer is coated with a hydrophobic hydrophobic thin film 160, which reduces the hysteresis at the contact angle between the top surface of the transparent substrate 110 and the meniscus M. That is, the hydrophobic thin film 160 may be provided between the dielectric thin film 120 and the first and second fluids A and B. The hydrophobic thin film 160 is preferably a fluoropolymer made of Teflon of a hydrophobic material, and more preferably, formed of amorphous fluorine carbide such as Teflon ^TM AF 1600 manufactured by DuPont ^™ . Furthermore, the thickness of the hydrophobic thin film 160 is between 5nm and 50㎛.

Adhesion of the hydrophobic thin film 160 by the second fluid B is the intersection of the hydrophobic thin film 160 and the meniscus M when no voltage is applied between the first electrode and the second electrode. Is almost identical to both sides of.

The first fluid A and the second fluid B are separated into two fluid bodies separated by the meniscus M and are incompatible with each other. When no voltage is applied between the first electrode 140 and the second electrode 150, the hydrophobic thin film 160 has higher adhesion to the first fluid A than the second fluid B. . Due to electro wetting, the adhesion by the second fluid B changes under voltage application between the first electrode and the second electrode, and the adhesion is three phase lines (hydrophobic thin film 160). And the contact line between the two fluids A and B) change the contact angles θ ₁ , θ ₂ , θ _{3 of the} meniscus. Therefore, the shape of this meniscus is variable according to the applied voltage.

In addition, when the hydrophobic thin film is not provided and the first and second fluids A and B are provided directly on the dielectric thin film 120, the dielectric thin film 120 may be connected to the first electrode 140. The second fluid B changes under the application of the voltage between the second electrodes 150 to have adhesion, thereby changing the shape of the meniscus M according to the voltage.

In addition, a hydrophilic thin film 170 and a hydrophobic thin film 160 are provided between the dielectric thin film 120 and the first and second fluids (A) and (B) in the preferred embodiment of the present invention. ) Is located on the top surface of the hydrophilic thin film 170 provided in a substantially circular shape in the center of the fluid lens, the first fluid (A) of the hydrophobic thin film 160 provided in a ring shape on the outside of the hydrophilic thin film 170 It is preferable to be located in the upper surface.

That is, after the hydrophilic thin film 170 is coated on the center of the dielectric thin film 120 and the hydrophobic thin film 160 is applied to the outside thereof, the hydrophilic thin film 170 is disposed on the hydrophilic thin film 170. B) is positioned in connection with the second electrode 150, the first fluid is in contact with the meniscus (M) while covering the upper surface of the hydrophobic thin film 160 and the outer peripheral surface of the second fluid (B) (A) is positioned so that the polymer film 130 is sealed in a substantially hemispherical shape.

In this configuration, since the hydrophilic thin film 170 is surrounded by the hydrophobic thin film 160 in the manufacturing process of the variable focus fluid lens according to the present invention, the hydrophilic second fluid B is placed on the hydrophilic thin film 170. Is very easy.

An example of a shape in which the meniscus M is changed by voltages applied to the first and second electrodes will be described.

Referring to FIG. 5, when a low voltage V ₁ , for example, a voltage between 0 V and 20 V is applied between the electrodes, the meniscus M uses a first concave meniscus shape. In this configuration, the initial contact angle θ ₁ between the meniscus M and the hydrophobic thin film 160 measured in the second fluid B is, for example, about 100 °. Since the refractive index of the first fluid A is higher than the refractive index of the second fluid B, the lens formed of the meniscus, here called a meniscus lens, has a relatively high negative magnification in this configuration.

In order to reduce the recess of the meniscus shape, a larger voltage is applied between the first electrode 140 and the second electrode 150. Referring to FIG. 2, when the intermediate voltage V ₂ , for example, between 20 V and 50 V is applied between the electrodes according to the thickness of the insulating layer, the meniscus M decreases compared with the meniscus of FIG. 5. A second concave meniscus shape with a radius of curvature is used. In this configuration, the intermediate contact angle θ ₂ between the first fluid A and the hydrophobic thin film 160 is, for example, about 60 °. Since the refractive index of the first fluid A is larger than that of the second fluid B, the meniscus lens in this configuration has a relatively low negative magnification.

In order to manufacture the convex meniscus shape, a much larger voltage is applied between the first electrode 140 and the second electrode 150. Referring to FIG. 7, for example, when a relatively high voltage V ₃ between 50 V and 100 V is applied between the electrodes, the meniscus M uses a meniscus shape in which the meniscus is convex. In this configuration, the maximum contact angle θ ₃ between the first fluid A and the hydrophobic thin film 160 is, for example, about 40 °. Since the refractive index of the first fluid A is larger than that of the second fluid B, the meniscus lens in this configuration has a positive magnification.

At this time, it is possible to use the relatively high magnification to achieve the configuration of FIG. 7, but in a practical embodiment the device including the lens as described is configured to use only low and medium magnifications within the above described range, i. As the electric field strength of the insulating layer is less than 20 V / mu m, and the fluid contact layer is charged by excessive voltage, it is preferable that the deterioration of the fluid contact layer is not used.

Also, at this time, the initially low voltage configuration will change (depending on their surface tension) according to the choice of the fluids A and B. By selecting an oil having a higher surface tension, and / or adding a component such as ethylene glycol to a salt solution that reduces its surface tension, the initial contact angle can be reduced, in which case the lens is shown in FIG. A low light magnification configuration corresponding to that shown and an intermediate magnification configuration corresponding to that shown in FIG. 7 may be used. In any case, the low magnification configuration is maintained so that the meniscus M is concave, and a relatively wide range of lens magnifications can be brought about without using excessive voltage.

In the above example, the refractive index of the fluid A is higher than that of the fluid B, but the fluid A may also have a lower refractive index than the fluid B. For example, the fluid A may be a fluorinated (fluorinated) oil having a lower refractive index than water. In this case, the amorphous fluoropolymer layer may be dissolved in the fluorinated oil, so it is preferable not to use it. Another fluid contact layer is, for example, a paraffin coating.

In addition, in the present invention, unlike the prior art, since the hydrophobic thin film 160 is provided on the transparent substrate 110 in a planar shape, the change in contact angle between the first fluid A and the hydrophobic thin film 160 is relatively small. Even when a low voltage is applied, the change can be easily performed.

On the other hand, the first electrode 140 and the second electrode 150 may be provided side by side on the top plane of the transparent substrate 110.

That is, as shown in FIGS. 5 to 7, the electrodes 140 and 150 are arranged side by side on the transparent substrate 110 and the first electrode 140 is hydrophobic with the first fluid A. FIG. In contact, the second electrode 150 is preferably provided to contact the hydrophilic second fluid (B).

Such a configuration is possible because the present invention is provided with an eye-shaped shape on the upper portion of the transparent substrate 110, and because of this configuration, the size of the present invention can be significantly reduced, and thus the variable focus fluid lens according to the present invention. Miniaturization of is possible.

Hereinafter will be described a method of manufacturing a variable focus fluid lens according to the present invention. 8A to 8F are views showing an example of a manufacturing process of a variable focus fluid lens according to an exemplary embodiment of the present invention. This will be described with reference.

1) electrode deposition step (S1)

In this step, the ITO metal electrode is deposited on the transparent substrate 110. Cr (200 nm) is deposited on the glass substrate (transparent substrate) on which ITO (250 nm) is deposited. It is etched for the mark and ITO is etched for electrode formation (Fig. 8 (a)).

2) insulating layer deposition step (S2)

The insulating layer of the dielectric thin film 120 such as parylene (900 nm) is formed on the ITO electrode (FIG. 8B).

3) hydrophobic thin film deposition step (S3)

Hydrophobic Tefron (Tefron AF 150 nm) is deposited by spin-coated onto the hydrophobic thin film 160 on the insulating layer (FIG. 8C).

4) Teflon and parylene pattern forming step (S4)

This step is a step of forming a pattern on the parylene and Teflon deposited in the step S3 and S4 to have the desired configuration of the present invention. A pattern is formed by performing multilayer lithography using LOR 30B (Microchem) and reactive ion etching (RIE). As shown in (d) of FIG. 8, in the variable focus fluid lens of the present invention, the second fluid B to be positioned at the center surrounds the second electrode 150 and the second fluid B to be positioned at the center. Since the first fluid A to be positioned must be in contact with the first electrode 140, it can be seen that a total of three etchings are formed by etching the hydrophobic thin film (Teflon) and the dielectric thin film (parylene).

5) Hydrophilic thin film forming step (S5) -optional step

In this step, the hydrophobic thin film 160 in the central portion is removed or replaced with the hydrophilic thin film 170 in order to easily locate the second fluid B in the central portion. To this end, the surface of the Teflon is changed by using double-layer lithography and oxygen plasma (FIG. 8 (d)).

6) fluid deposition step (S6)

Positioning the second fluid (B) relative to the center (optical axis, optical axis) of the substrate on which the step S4 or S5 is completed and depositing the first fluid (A) surrounding the polymer film 130 of parylene material These are sealed while wrapping them (FIG. 8 (e)).

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is intended by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

M: meniscus
A: First fluid
B: second fluid
110: transparent substrate
120: dielectric thin film
130: polymer film
140: first electrode
150: second electrode
160: hydrophobic thin film
170: hydrophilic thin film

Claims (11)

delete In a variable focus fluid lens using electro wetting,
Transparent substrate 110;
A dielectric thin film 120 deposited on an upper surface of the transparent substrate 110;
Hemispherical shape with the first fluid (A) and the second fluid (B) filled in contact with each other on the meniscus (M) without being mixed with each other with different refractive indices on the dielectric film 120. A polymer film 130 sealed with;
A first electrode 140 insulated from the second fluid B by the dielectric thin film 120;
And a second electrode 150 provided to act on the second fluid B.
The first electrode 140 and the second electrode 150 is a variable focus fluid lens, characterized in that provided in parallel to the upper surface of the transparent substrate (110). The method of claim 2,
A variable focus fluid lens, characterized in that a hydrophobic thin film is provided between the dielectric thin film 120 and the first and second fluids (A) and (B). The method of claim 2,
A hydrophilic thin film 170 and a hydrophobic thin film 160 are provided between the dielectric thin film 120 and the first and second fluids (A) and (B).
The second fluid (B) is located on the upper surface of the hydrophilic thin film 170 provided in a substantially circular shape around the central portion of the fluid lens, the first fluid (A) is ring-shaped on the outside of the hydrophilic thin film (170) Variable focus fluid lens, characterized in that located on the upper surface of the hydrophobic thin film (160) provided. The method of claim 2,
The first fluid (A) is a non-conductive fluid, the second fluid (B) is a variable focus fluid lens, characterized in that the conductive fluid. The method of claim 2,
The difference in density between the first fluid (A) and the second fluid (B) is within 30% variable focus lens. The method according to claim 3 or 4,
The hydrophobic thin film is a variable focus fluid lens, characterized in that the fluoropolymer (fluoropolymer). The method according to any one of claims 2 to 6,
The polymer film 130 is a variable focus fluid lens, characterized in that using parylene (parylene). The method according to any one of claims 2 to 6,
The first fluid (A) is a variable focus fluid lens, characterized in that using any one of mineral oil, silicone oil, sunflower oil, hexadecane (hexadecane). The method according to any one of claims 2 to 6,
The dielectric thin film (120) is a variable focus fluid lens, characterized in that using parylene (parylene). The method according to any one of claims 2 to 6,
The first electrode 140 is in contact with the first fluid (A), characterized in that the variable focus fluid lens.

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