JP2007121821A - Optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element capable of inclining a center axis passing through the center of a boundary shape between a first liquid and a second liquid, capable of more reducing the size of the optical element in a direction orthogonal to the optical axis of a photographing optical system than a conventional optical element, and advantageous to downsize not only the optical element itself but also a lens barrel or an imaging apparatus having the optical element. <P>SOLUTION: A first electrode 18 is formed facing the inside of a container 12 so that at least a part of the electrode 18 is touched with the first liquid 14 and circularly extended on the outer periphery of a first end face wall 1202 along the peripheral direction, and an aperture 1802 is formed on the inside. A second electrode 20 is formed on a portion of a sidewall 1206 facing a storing room 12A and extended along the peripheral direction of the sidewall 1206 over almost the whole area of the sidewall 1206 in the thickness direction of the container 12. The second electrode 20 is constituted of a plurality of divided bodies 22 separated along the peripheral direction of the sidewall 1206 and respective divided bodies 22 show the same shape. A power source 30 is constituted so as to apply voltages of different values to respective divided bodies 22. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical element.

An imaging apparatus such as a digital still camera or a digital video camera captures a subject image by forming a subject image guided by a photographing optical system on an image sensor.
By the way, when the hand holding the imaging device moves during shooting and so-called camera shake occurs, image blur occurs in the subject image formed on the image sensor.
In order to prevent such image blurring, a correction lens is provided in a part of the photographing optical system so as to be movable along a plane orthogonal to the optical axis of the photographing optical system, and the correction lens is moved along the plane. There has been proposed an image blur prevention device that provides a drive mechanism for preventing image blur of a subject image formed on an image sensor by moving a correction lens by the drive mechanism when image blur occurs. (See Patent Documents 1 and 2).

In the above prior art, since the drive mechanism has a coil and a magnet, the structure is complicated, the occupied space is increased, and there is a disadvantage in miniaturization.
In order to solve such a problem, a lens in which a correction lens is configured by an optical element using an electrowetting effect has been proposed (see Patent Document 3).
This optical element forms a lens by enclosing two kinds of liquids, a polar liquid and a nonpolar liquid, in a container and forming the interface shape of the two liquids into a spherical shape. The correction lens formed by the optical element is moved along a plane orthogonal to the optical axis of the photographing optical system by applying a potential gradient along the plane orthogonal to the optical axis to the liquid of ing.
Japanese Patent Publication No. 2641172 JP 2000-258813 A Japanese Patent Laid-Open No. 2005-55286

By the way, in the conventional technique in which the correction lens is configured by the optical element, the correction lens is moved along a plane orthogonal to the optical axis of the photographing optical system, and thus the size in the direction orthogonal to the optical axis of the photographing optical system is reduced. There was a disadvantage in the above, and there was a limit in miniaturization.
The present invention has been made in view of such circumstances, and an object thereof is to provide an optical element that is advantageous in reducing the size.

In order to achieve the above-mentioned object, the present invention has first and second end face walls that face each other in the thickness direction, and side walls that connect the first and second end face walls. A container in which an enclosed chamber is formed, a polar or conductive first liquid enclosed in the accommodation chamber, and a first liquid that is enclosed in the accommodation chamber and does not mix with the first liquid. 2 liquid and a voltage applying means for applying a voltage to the first liquid, the voltage applying means being provided on the first end wall and at least a part of which is in contact with the first liquid. A first electrode; and a second electrode facing the second liquid that extends along a circumferential direction of the side wall at a position of the side wall facing the storage chamber, and the voltage The interface shape between the first liquid and the second liquid is bent by voltage application by the applying means. An optical element that refracts light passing through the interface by traveling in the thickness direction of the container through the first and second end face walls, and the second electrode is It is comprised by the some division body cut | disconnected along the circumferential direction of the said side wall.
In addition, the present invention includes first and second end face walls that face each other in the thickness direction, and a side wall that connects the first and second end face walls, and is hermetically sealed inside them. A container in which a chamber is formed, a polar or conductive first liquid sealed in the storage chamber, a second liquid sealed in the storage chamber and not mixed with the first liquid, Voltage applying means for applying a voltage to the first liquid, and the voltage applying means is provided on the first end face wall, and at least a part of the first liquid is in contact with the first liquid. A first electrode provided extending along the circumferential direction of the end wall, and a second electrode provided along the circumferential direction of the side wall at the location of the side wall facing the storage chamber. And a boundary between the first liquid and the second liquid by voltage application by the voltage application means. An optical element that refracts light passing through the interface by traveling in the thickness direction of the container through the first and second end face walls by deforming the shape into a curved surface. The electrode is composed of a plurality of divided bodies cut along the circumferential direction of the first end face wall.

  According to the optical element of the present invention, by configuring the second electrode or the first electrode of the optical element with a plurality of divided bodies, the value gradually changes along the direction in which the divided bodies are arranged in each divided body. By applying a voltage to be applied, the central axis passing through the center of the interface shape between the first liquid and the second liquid can be tilted, and is orthogonal to the optical axis of the imaging optical system as compared with a conventional optical element. This is advantageous in reducing the size of the optical element and, in turn, downsizing the lens barrel and the imaging device having the optical element.

First, the principle of the electrocapillary phenomenon (electrowetting phenomenon) used by the optical element of the present invention will be described.
13A and 13B are explanatory diagrams of the principle of the electrocapillarity, in which FIG. 13A shows a state before voltage application, and FIG. 13B shows a state after voltage application.
As shown in FIG. 13A, the first electrode 2 is formed on the surface of the substrate 1, and the insulating film 3 is formed on the electrode 2.
A polar or conductive first liquid 4 is located on the surface of the insulating film 3, and a second electrode 5 is electrically connected to the first liquid 4.
As shown in FIG. 13A, when the voltage E is not applied between the first electrode 2 and the second electrode 5, the surface of the first liquid 4 protrudes upward due to surface tension. It is almost spherical. At this time, the liquid surface angle θ at the surface of the insulating film 3 and the portion where the first liquid 4 is in contact with the insulating film 3, that is, the contact angle θ is set to θ0. The contact angle θ is measured with the liquid facing the air, in other words, measured at the gas-liquid interface.
However, as shown in FIG. 13B, when a voltage E is applied between the first electrode 2 and the second electrode 5, for example, a positive charge is charged on the surface of the insulating film 3. An electric field (electrostatic force) acts on the molecules constituting the first liquid 4. As a result, the molecules constituting the first liquid 4 are attracted, so that the wettability of the first liquid 4 to the insulating film 3 is improved, and the contact angle θ is θ1 smaller than θ0. Further, the contact angle θ decreases as the value of the voltage E increases.
Such a phenomenon is called an electrocapillary phenomenon.

Next, the optical element 10 of the present embodiment will be described.
1 is a longitudinal sectional view showing the configuration of the optical element 10, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is a perspective view in which a part of the optical element 10 is omitted.
As shown in FIG. 1, the optical element 10 includes a container 12, a first liquid 14, a second liquid 16, and a voltage applying unit.
The container 12 includes a first end face wall 1202 and a second end face wall 1204 that face each other in the thickness direction, and a side wall 1206 that connects the first and second end face walls 1202 and 1204. The housing chamber 12 </ b> A is hermetically sealed by a side wall 1206 connecting the first and second end face walls 1202 and 1204.
In the present embodiment, the first and second end face walls 1202 and 1204 have a disk shape having the same diameter, and the side wall 1206 has the same size as the outer diameter of the first and second end face walls 1202 and 1204. It has a cylindrical shape with an outer diameter, and the storage chamber 12A has a flat columnar shape.
The first and second end face walls 1202 and 1204 and the side wall 1206 are made of an insulating material, and the first and second end face walls 1202 and 1204 are made of a transparent material that transmits light. Is formed.
As a material constituting the first and second end face walls 1202 and 1204, for example, a transparent and insulating synthetic resin material or a transparent glass material can be used.

The first liquid 14 has polarity or conductivity and is enclosed in the storage chamber 12A.
The second liquid 16 is not mixed with the first liquid 14 and is enclosed in the storage chamber 12A.
Further, the first liquid 14 and the second liquid 16 have substantially the same specific gravity, and the refractive index n1 of the first liquid 14 is higher than the refractive index n2 of the second liquid 16.
In the present embodiment, the second liquid 16 is composed of silicon oil, the first liquid 14 is composed of a mixture of ethylene glycol and ethanol, the specific gravity is substantially equal to the above-described silicon oil, and refraction is performed. The rate n1 is formed higher than the refractive index n2 of silicon oil.
Examples of the liquid that can be used as the first liquid 14 include nitromethane, acetic anhydride, methyl acetate, ethyl acetate, methanol, acetonitrile, acetone, ethanol, propionitrile, tetrohydrofuran, n-hexane, 2-propanol, 2-butanone, n-butyronitrile, 1-propanol, 1-butanol, dimethyl sulfoxide, chlorobenzene, ethylene glycol, formamide, nitrobenzene, propylene carbonate, 1,2-dichloroethane, carbon disulfide, chloroform, bromobenzene, carbon tetrachloride, Trichloroacetic anhydride, toluene, benzene, ethylenediamine, N, N-dimethylacetamide, N, N-dimethylformamide, tributyl phosphate, pyridine, benzonitrile, aniline, 1,4-dioxane, hex Such as methyl phosphoramide and the like.
Examples of the liquid that can be used as the second liquid 16 include silicon, decane-based, octane-based, nonane, and heptane.
The first liquid 14 and the second liquid 16 may be formed of a single liquid, or may be formed by mixing a plurality of liquids. In short, the first liquid 14 and the second liquid 16 have substantially the same specific gravity, and the refractive index n1 of the first liquid 14 is higher than the refractive index n2 of the second liquid 16. That's fine.

The voltage application means includes the first electrode 18, the second electrode 20, and the power supply 30.
As shown in FIG. 1, the first electrode 18 (positive electrode) is for applying a voltage to the first liquid 14, and is formed on the first end face wall 1202.
The first electrode 18 is formed so as to face the inside of the container 12 so that at least a part thereof is in contact with the first liquid 14. In the present embodiment, the first electrode 18 is a single unit, The first end face wall 1202 is formed in an annular shape along the circumferential direction on the outer periphery, and an opening 1802 is formed on the inner side.
In other words, the first liquid 14 has a portion that always faces the outer peripheral portion of the first end face wall 1202 regardless of the change in the shape of the interface 28, and the first electrode 18 has the first liquid 18. 14 is formed in the outer peripheral part of the 1st end surface wall 1202 which always faces.
As shown in FIGS. 1 and 2, the second electrode 20 (negative electrode) is formed at a position of the side wall 1206 facing the storage chamber 12 </ b> A.
In the present embodiment, the second electrode 20 is provided so as to extend along the circumferential direction of the side wall 1206, and extends over substantially the entire side wall 1206 in the thickness direction of the container 12.
The first and second electrodes 18 and 20 are made of a conductive material such as copper plating or an ITO film (Indium Tin Oxide film), for example.
As shown in FIG. 1, the power supply 30 is provided outside the container 12 and the output voltage is variable. The positive voltage output terminal of the power supply 30 is electrically connected to the first electrode 18, and the negative voltage output of the power supply 30 is provided. A terminal is electrically connected to the second electrode 20.

As shown in FIG. 2, the insulating film 24 is formed so as to cover the entire area where the second electrode 20 faces the storage chamber 12 </ b> A. In the present embodiment, the insulating film 24 covers the entire area of the second electrode 20. It is formed in a cylindrical shape so as to cover it.
Accordingly, when a voltage is applied to the first electrode 18 and the second electrode 20, for example, a positive charge is charged on the surface of the insulating film 24, whereby an electric field (electrostatic force) is applied to the molecules constituting the first liquid 14. ) Acts to generate an electrocapillary phenomenon.
In the present embodiment, the first electrode 18, the second electrode 20, the insulating film 24, and the power supply 30 constitute the voltage applying unit.
A water repellent film 26 is formed so as to cover the insulating film 24.
The water repellent film 26 is configured such that the wettability with respect to the second liquid 16 is higher than the wettability with respect to the first liquid 14.
That is, when the contact angle of the second liquid 16 with respect to the water repellent film 26 is measured in the air (at the gas-liquid interface) as in the case of FIG. The value is smaller than the contact angle of one liquid 14.
The water repellent film 26 is an oleophilic film, and can be formed, for example, by baking a material containing silicon as a main component or by forming a material made of an amorphous fluororesin. As the water repellent film 26, various conventionally known materials can be used.

The first liquid 14 contacts the first electrode 18 on the first end face wall 1202 and the first liquid 14 faces the side wall 1206 in a state where no voltage is applied by the voltage applying means. The location is located on the second electrode 20 via the insulating film 24 and the water repellent film 26, and the second liquid 16 is located on the second end face wall 1204, and the second liquid 16 is A portion facing the side wall 1206 is located on the water repellent film 26.
Therefore, when a voltage is applied from the power supply 30 to the first electrode 18 and the second electrode 20, the surface of the insulating film 24 is charged, and an electric field (electrostatic force) is applied to the molecules constituting the first liquid 14. Will act.
In addition, in the state where no voltage is applied by the voltage applying means, the interface 28 between the first liquid 14 and the second liquid 16 is changed from the first liquid 14 to the second as shown in FIGS. A convex curved surface is formed toward the liquid 16. In FIG. 3, in order to simplify the drawing, the first end face wall 1202 and the second liquid 16 are removed, and the boundary line between the insulating film 24 and the water repellent film 26 is omitted.
Here, since the refractive index n1 of the first liquid 14 is formed higher than the refractive index n2 of the second liquid 16, the thickness of the container 12 passes through the first and second end face walls 1202 and 1204. The light traveling in the direction and passing through the interface 28 is refracted at the interface 28, and thus the optical element 10 constitutes a lens 32 having a power for converging the light.

As shown in FIG. 2, the second electrode 20 is composed of a plurality of divided bodies 22 cut along the circumferential direction of the side wall 1206, and each divided body 22 has the same shape.
In the present embodiment, each of the divided bodies 22 is provided so that the extending lengths extending in the circumferential direction are the same.
An X axis and a Y axis perpendicular to the first and second end face walls 1202 and 1204 and perpendicular to each other through the central axis on a plane perpendicular to the central axis passing through the centers of the first and second end face walls 1202 and 1204. When an axis is assumed, each divided body 22 is arranged so as to be line symmetric with respect to the X axis, and is arranged so as to be line symmetric with respect to the Y axis.
Note that the power supply 30 is configured to be able to apply different values of voltage to each of the divided bodies 22.

Next, the operation of the optical element 10 will be described.
First, the case where the optical element 10 is used as a normal lens will be described.
4A and 4B are explanatory views of an angle θ formed by the first liquid 14 and the water repellent film 26, and FIG. 5 is a cross-sectional view taken along the line BB of FIG.
In a state where no voltage is applied from the power source 30 to the first electrode 18 and the second electrode 20 (E = 0V), the shape of the interface 28 between the first and second liquids 14 and 16 is shown by a solid line in FIG. Thus, a convex curved surface from the first liquid 14 toward the second liquid 16 is determined by the balance between the surface tension of the first and second liquids 14 and 16 and the interfacial tension on the water repellent film 26. There is no.
The first liquid 14 is located on the first end face wall 1202, and the second liquid 16 is located on the second end face wall 1204.
As shown in FIG. 4A, the second liquid 16 enters the first liquid 14 along the side wall 1206 at the side wall 1206 (water repellent film 26).
At this time, an angle θ formed by the first liquid 14 and the insulating film 26 is θ0.
Such a positional relationship between the first liquid 14 and the second liquid 16 is caused by the formation of the water repellent film 26 on the side wall 1206, in other words, the first, This is caused by the difference in the contact angle between the second liquids 14 and 16.
At this time, the central axis L1 of the lens 32 (optical axis of the lens 32), in other words, the central axis passing through the center of the shape of the interface 28 passes through the centers of the first and second end face walls 1202 and 1204, and the first axis. The second end face walls 1202 and 1204 are orthogonal to each other.

Next, when a voltage E1> 0V is applied between the first electrode 18 and the second electrode 20 from the power supply 30, that is, when the same voltage E1 is applied to each divided body 22, Due to the electrocapillary phenomenon, the wettability of the first liquid 14 with respect to the water repellent film 26 is increased (the contact angle is reduced), and the first liquid 14 is in contact with the water repellent film 26 as shown in FIG. The angle θ to be formed is an angle θ1 larger than θ0, and in the side wall 1206 (water repellent film 26), compared to the case where no voltage is applied to the first electrode 18 and the second electrode 20, The first liquid 14 enters the second liquid 16 more greatly along the side wall 1206. Therefore, the inclination of the curved curved surface (spherical surface) of the interface 28 is reduced.
The slope of the curved curved surface (spherical surface) of the interface 28 decreases as the voltage E increases. The center axis L1 of the lens 32 passes through the centers of the first and second end face walls 1202 and 1204 and is orthogonal to the first and second end face walls 1202 and 1204 regardless of the increase or decrease of the voltage E. Holding.
Therefore, the focal length of the lens 32 can be varied by changing the curvature of the interface 28 by adjusting the voltage E (the power of the lens 32 can be varied).

Next, when applying a voltage whose value gradually changes along the direction in which the divided bodies 22 are arranged in each divided body 22 of the second electrode 20, in other words, the first liquid 14 is applied to the second electrode 20. The operation when a voltage gradient is given along the circumferential direction of the side wall 1206 at the location facing the above will be described.
For convenience of explanation, in FIG. 2, each divided body 22 will be described with reference numerals 22A, 22B, 22C, 22D, 22E, 22F, 22G, and 22H.
In addition, the division bodies 22A, 22B, 22C, 22D, 22E, 22F, 22G, and 22H are positioned in this order counterclockwise from the division body 22A along the circumferential direction of the side wall 1206, and at both ends of the X axis. The divided bodies 22A and 22E are located, and the divided bodies 22C and 22G are located at both ends of the Y axis.

FIG. 6 is a diagram showing the magnitude of the voltage E applied to each divided body 22.
As shown in FIG. 6, voltages applied from the power source 30 to the divided bodies 22A, 22B, 22C, 22D, 22E, 22F, 22G, and 22H are voltages E1, E2, E3, E4, E5, E4, E3, and E2, respectively. And
And the magnitude | size of the voltage applied to each division | segmentation body 22 by the power supply 30 is set to E1 <E2 <E3 <E4 <E5, By the direction in which these division | segmentation bodies 22A thru | or 22H were arranged in each division body 22A thru | or 22H. A voltage whose value gradually changes along is applied. That is, the voltage applied to each divided body 22 has a voltage gradient that gradually increases (decreases) along the X axis, and the divided bodies 22 at positions symmetrical with respect to the X axis have the same voltage. Apply.
Then, a gradient corresponding to the magnitude of the voltage is generated in the magnitude of the electric field (electrostatic force) acting on the first liquid 14 portion facing each of the divided bodies 22A to 22H.
Therefore, a gradient also occurs in the contact angle of the first liquid 14 portion facing each divided body 22A to 22H with respect to the water-repellent film 26, and the first liquid 16 portion facing each divided body 22A to 22H is the first. Each of the sizes of the liquids 14 enters also has a gradient.
As a result, the curved surface of the interface 28 is deformed as indicated by a broken line in FIG.
That is, by applying a voltage gradient to each of the divided bodies 22A to 22H, the curved surface of the interface 28 is deformed, whereby the tip of the curved surface of the interface 28 is displaced closer to the divided body 22A to which the lowest voltage E1 is applied.
As a result, the central axis L2 of the lens 32 is inclined in a direction intersecting the central axis L1, and is inclined with respect to the first and second end face walls 1202 and 1204. In other words, the lens 32 is covered. (Tilted state). That is, the shape of the interface 28 is deformed so that the center axis of the interface shape tilts.
That is, the inclination of the central axis of the lens 32 constituted by the optical element 10 can be adjusted by adjusting the voltage applied to each of the divided bodies 22A to 22H.

Next, the imaging device 40 to which the above-described optical element 10 is applied will be described.
FIG. 7 is a block diagram illustrating a configuration of the imaging device 40.
The imaging device 40 is a digital still camera, and has a case 42 that constitutes an exterior. The case 42 is provided with a lens barrel 46 in which a photographing optical system 44 is incorporated. An image sensor 48 that captures a subject image guided by the system 44 is accommodated.
The lens barrel 46 is provided with the optical element 10 according to the present invention, and a subject image guided by the photographing optical system 44 is formed on the image sensor 48 through the optical element 10.
The case 42 is provided with a display 49 including a liquid crystal display panel for displaying an image or the like.
The imaging device 40 includes a video signal amplification unit 50, a video signal processing unit 52, a video signal recording / playback unit 54, a control unit 56, a monitor driver 58, an internal memory 60, a memory card interface 62, a memory card slot 64, an external An input / output interface 66, an external input / output terminal 68, an operation panel unit 70, a camera shake detection unit 72, a camera shake signal processing unit 74, a device driving unit 76, and the like are provided.

The imaging signal generated by the imaging device 48 is amplified by the video amplification unit 50, subjected to predetermined signal processing by the video signal processing unit 52, and supplied as a video signal to the video signal recording / reproducing unit 54.
The video signal recording / reproducing unit 54 records the video signal supplied from the video signal processing unit 52 in a memory card 78 as a recording medium mounted in the memory slot 64 via the interface 62 under the control of the control unit 56.
The video signal recording / reproducing unit 54 supplies the video signal supplied from the video signal processing unit 52 or the video signal supplied from the memory card 78 via the interface 62 to the display 49 via the monitor driver 58. To display the image.
The control unit 56 controls the video signal recording / reproducing unit 54 based on operations of a shutter button and various operation switches provided on the operation panel unit 70.
The internal memory 60 provides a memory area necessary for the operation of the video signal recording / reproducing unit 54.
The external input / output interface 66 controls transmission / reception of a video signal between an external electronic device connected to the external input / output terminal 68 and the video signal recording / reproducing unit 54.

The camera shake detection unit 72 detects camera shake based on acceleration or vibration applied to the imaging device 40, and outputs a camera shake detection signal corresponding to the magnitude of the camera shake.
As the camera shake detection unit 72, for example, various conventionally known sensors such as a gyro sensor can be used.
The camera shake signal processing unit 74 processes the first camera shake detection signal as an analog signal supplied from the camera shake detection unit 72, and the second camera shake detection signal as a digital signal indicating the direction of camera shake, the size of the camera shake, and the like. Is generated and supplied to the control unit 56.
The control unit 56 generates a camera shake correction signal based on the second camera shake correction signal supplied from the camera shake signal processing unit 74 and supplies the camera shake correction signal to the device driving unit 76.
The device driving unit 76 includes the power source 30 of the optical element 10 described above, and controls the power source 30 based on a camera shake correction signal supplied from the control unit 56 to supply a voltage to each divided body 22. It is configured as follows.
The optical element 10 is arranged so that the central axis L1 of the lens 32 coincides with the optical axis of the photographing optical system 44 in the state where the same voltage is applied to each divided body 22.

Next, an operation of camera shake correction (image shake correction) using the optical element 10 in the imaging device 40 will be described.
8A and 8B are explanatory diagrams of image blur correction by the lens 32. FIG. 8A shows a state where the image blur is not corrected, and FIG. 8B shows a state where the image blur is corrected.
It is assumed that the user is holding the imaging device 40 and shooting.
At that time, the camera shake signal detection unit 72 detects the camera shake, and the camera shake signal processing unit 74 supplies the second camera shake signal to the control unit 56.
The control unit 56 provides the device driving unit 76 with the camera shake correction signal generated based on the second camera shake signal.
As a result, the device driving unit 76 cancels image blur that occurs on the image sensor 48 due to the camera shake so that the central axis of the lens 32 is inclined in accordance with the detected magnitude and direction of the camera shake. The power supply 30 is controlled so that the central axis of the lens 32 is tilted at the required size and angle, and a voltage is supplied to each divided body 22.
Therefore, in a state in which no camera shake is detected, the optical element 10 is in a state where the central axis L1 of the lens 32 matches the optical axis of the imaging optical system 44 as shown in FIG. Therefore, the light 2 from the subject converges on the image sensor 48 along the central axis L1 of the lens 32 and forms an image.
On the other hand, when camera shake is detected, as shown in FIG. 8B, the optical element 10 is tilted at a direction and an angle necessary for the center axis L2 of the lens 32 to eliminate image shake due to camera shake.
Therefore, the light 2 from the subject is converged and imaged on the image sensor 48 along the center axis L2 of the tilted lens 32.

According to the present embodiment, the second electrode 20 of the optical element 10 is configured by the plurality of divided bodies 22 cut along the circumferential direction of the side wall 1206 of the container 12, so that the divided bodies 22 are arranged. By applying a voltage whose value gradually changes along the determined direction (by applying a voltage gradient along the circumferential direction of the side wall 1206 to the location where the first liquid 14 faces the second electrode 20) The central axis of the lens 32 can be tilted by changing the shape of the interface 28 formed between the first liquid 14 and the second liquid 16.
That is, the conventional optical element moves the lens along a plane perpendicular to the optical axis of the photographing optical system, whereas the optical element 10 of the present invention has a VAP (variable angle prism) system. As in the case of the active prism method, the optical axis of the lens 32 is inclined with respect to the optical axis of the photographing optical system.
Therefore, as compared with the conventional optical element, it is only necessary to incline the optical axis of the lens 32. Therefore, the dimension of the optical element 10 in the direction orthogonal to the optical axis of the photographing optical system can be reduced. This is advantageous in reducing the size of the lens barrel and the size of the lens barrel and the imaging device.

In this embodiment, the water-repellent film 26 is provided so as to cover the insulating film 24, but the insulating film 24 has a property that the wettability with respect to the second liquid 16 is higher than the wettability with respect to the first liquid 14. The insulating film 24 and the water repellent film 26 can be used together.
In the present embodiment, the case where the second electrode 20 is configured by eight divided bodies 22 has been described. However, the number of the divided bodies 22 may be plural, and is not limited.
However, as the number of the divided bodies 22 is increased and the difference in voltage between the adjacent divided bodies 22 is reduced, the change in the curved surface of the interface 28 can be made smoother. This is advantageous in suppressing the distortion generated in the film.

In addition, although the camera shake is generated in the horizontal direction, the correction of the image shake by the lens 32 includes an oblique component in addition to the horizontal component, or the camera shake is generated only in the vertical direction. Nevertheless, when the image blur correction by the lens 32 includes an oblique component in addition to the vertical component, an oblique image blur occurs in the corrected image. Such an image is known to have a noticeable image blur when viewed by a human.
Therefore, when camera shake occurs only in the horizontal direction or only in the vertical direction, it is preferable that correction of image blur by the lens 32 does not include an oblique component.
Therefore, the number of divided bodies 22 is a number that is a multiple of 4 (4, 8, 16,...), And the horizontal direction (X-axis direction) of the optical element 10 with the imaging optical system of the imaging device 40 facing the subject. ) And the vertical direction (Y-axis direction) are arranged so that the divided body 22 is symmetric, and when the camera shake occurs only in the horizontal direction or only in the vertical direction, the image shake caused by the lens 32 is reduced. The correction can be made not to include a component in an oblique direction, which is advantageous and preferable in securing the quality of the image after correction.

In the present embodiment, the first electrode 18 is formed in an annular shape on the first end face wall 1202 and has an opening 1802 in the center. However, the first electrode 18 is formed in the first liquid 14. It only needs to be in constant contact. For example, the first electrode 18 may be formed of a transparent ITO film or the like and may be formed in a disk shape over the entire first end wall 1202, or the first electrode 18 may be formed on the first end wall 1202. It may be formed in a rod shape or a needle shape that penetrates and contacts the first liquid 14.
However, when the opening 1802 is formed in the first electrode 18 as in the present embodiment, it is advantageous to ensure the light transmittance in the portion of the opening 1802.
In the present embodiment, the second electrode 20 is formed over substantially the entire side wall 1206 in the thickness direction of the container 12, but the second electrode 20 has an electric field with respect to the first liquid 14. Therefore, the second electrode 20 only needs to extend over at least a portion of the side wall 1206 in which the second liquid 16 moves in the thickness direction of the container 12.

(Second Embodiment)
Next, a second embodiment will be described.
The second embodiment is different from the first embodiment in that the first electrode 18 is single and the second electrode 20 is composed of a plurality of divided bodies 22 in the first embodiment. In contrast to this, in the second embodiment, the first electrode 18 is composed of a plurality of divided bodies 19 and the second electrode 20 is single, and the other points are the first. This is the same as the embodiment.
FIG. 9 is a cross-sectional view showing the configuration of the optical element 10 of the second embodiment, and FIG. 10 is a plan view of the second electrode 20 in the second embodiment. In the following description, the same parts and members as those in the first embodiment are denoted by the same reference numerals.
As shown in FIG. 9, the second electrode 20 is provided so as to extend along the circumferential direction of the side wall 1206 and is formed as a single unit, and substantially the entire side wall 1206 in the thickness direction of the container 12. Extending over.
The first electrode 18 is formed so as to face the inside of the container 12 so that at least a part thereof is in contact with the first liquid 14, and has an annular shape along the circumferential direction on the outer periphery of the first end face wall 1202. An opening 1802 is formed on the inside.
And the 1st electrode 18 is comprised by the some division body 19 cut | disconnected along the circumferential direction, and each division body 19 is exhibiting the same shape.
In the second embodiment, each of the divided bodies 19 is provided with eight pieces, and the extending lengths extending in the circumferential direction are the same.
An X axis and a Y axis perpendicular to the first and second end face walls 1202 and 1204 and perpendicular to each other through the central axis on a plane perpendicular to the central axis passing through the centers of the first and second end face walls 1202 and 1204. When an axis is assumed, each divided body 19 is arranged so as to be line symmetric with respect to the X axis, and is arranged so as to be line symmetric with respect to the Y axis.
The power supply 30 is configured to be able to apply different values of voltage to each divided body 19.

  The operation of the optical element 10 will be described. As in the first embodiment, in the state where no voltage is applied from the power supply 30 to the first electrode 18 and the second electrode 20 (E = 0V), the first and second The shape of the interface 28 between the two liquids 14 and 16 is determined by the balance between the surface tension of the first and second liquids 14 and 16 and the interfacial tension on the water repellent film 26, as shown by the solid line in FIG. A convex curved surface is formed from the first liquid 14 toward the second liquid 16, and the central axis of the lens 32 (the optical axis of the lens 32) L1, in other words, the central axis passing through the center of the shape of the interface 28 is The first and second end face walls 1202 and 1204 pass through the center and are orthogonal to the first and second end face walls 1202 and 1204.

Next, when the voltage E1> 0 V is applied between the first electrode 18 and the second electrode 20 from the power supply 30, and the same voltage E1 is applied to each divided body 19, the first implementation is performed. Similarly to the embodiment, the slope of the curved curved surface (spherical surface) of the interface 28 is reduced by the electrocapillary phenomenon.
The slope of the curved curved surface (spherical surface) of the interface 28 decreases as the voltage E increases. The center axis L1 of the lens 32 passes through the centers of the first and second end face walls 1202 and 1204 and is orthogonal to the first and second end face walls 1202 and 1204 regardless of the increase or decrease of the voltage E. Holding.
Therefore, the focal length of the lens 32 can be varied by changing the curvature of the interface 28 by adjusting the voltage E (the power of the lens 32 can be varied).

Next, when a voltage whose value gradually changes along the direction in which the divided bodies 19 are arranged is applied to the voltage applied to each divided body 19 of the first electrode 18, in other words, applied to each divided body 19. The operation when a gradient is applied to the voltage will be described.
For convenience of explanation, in FIGS. 9 and 10, each divided body 19 will be described with reference numerals 19A, 19B, 19C, 19D, 19E, 19F, 19G, and 19H.
The divided bodies 19A, 19B, 19C, 19D, 19E, 19F, 19G, and 19H are positioned in this order counterclockwise from the divided body 19A along the circumferential direction of the side wall 1206, and at both ends of the X axis. The divided bodies 19A and 19E are located, and the divided bodies 19C and 19G are located at both ends of the Y axis.

FIG. 11 is a diagram showing the magnitude of the voltage E applied to each divided body 19.
As shown in FIG. 11, voltages applied from the power source 30 to the divided bodies 19A, 19B, 19C, 19D, 19E, 19F, 19G, and 19H are voltages E1, E2, E3, E4, E5, E4, E3, and E2, respectively. And
And the magnitude | size of the voltage applied to each division | segmentation body 19 with the power supply 30 is set to E1 <E2 <E3 <E4 <E5, By the direction in which these division | segmentation body 19A thru | or 19H were arranged in each division body 19A thru | or 19H. A voltage whose value gradually changes along is applied. In other words, a voltage gradient is applied along the circumferential direction of the first end face wall 1202 at the location where the first liquid 14 faces the first electrode 18.
That is, a gradient is applied so that the voltage applied to each divided body 19 gradually increases (decreases) along the X axis, and the same voltage is applied to the divided bodies 19 at positions symmetrical with respect to the X axis. To do.
Then, a gradient corresponding to the magnitude of the voltage also occurs in the magnitude of the electric field (electrostatic force) acting on the first liquid 14 portion facing each of the divided bodies 19A to 19H.
Therefore, a gradient is also generated in the contact angle of the first liquid 14 portion facing each divided body 19A to 19H with respect to the water repellent film 26, and the first liquid 16 portion facing each divided body 19A to 19H is first. Each of the sizes of the liquids 14 enters also has a gradient.
As a result, the curved surface of the interface 28 is deformed as in the first embodiment.
That is, by applying a voltage gradient to each of the divided bodies 19A to 19H, the curved surface of the interface 28 is deformed, whereby the tip of the curved surface of the interface 28 is displaced closer to the divided body 19A to which the lowest voltage E1 is applied.
As a result, the central axis L2 of the lens 32 is inclined in a direction intersecting the central axis L1, and is inclined with respect to the first and second end face walls 1202 and 1204. In other words, the lens 32 is covered. (Tilted state). That is, the shape of the interface 28 is deformed so that the center axis of the interface shape tilts.
That is, the inclination of the central axis of the lens 32 formed by the optical element 10 can be adjusted by adjusting the voltage applied to each of the divided bodies 19A to 19H.

The same effects as those of the first embodiment can also be achieved by such a second embodiment.
In the second embodiment, the case has been described in which each divided body 19 has an annular shape separated along the circumferential direction and has the same shape. However, the shape of each divided body 19 is limited to this. What is necessary is just to be able to apply a voltage to the part of the first liquid 14 that faces the divided body 19. For example, the divided body 19 exhibits the same shape obtained by dividing a circle with radiation passing through the center thereof. It may be.
Further, in the second embodiment, the second electrode 20 is not formed in a single unit, but is configured by a plurality of divided bodies 22 as in the first embodiment. For example, the first electrode 18 is divided. The number of the bodies 19 and the divided bodies 22 of the second electrode 20 are the same, and the divided bodies 19 and 22 are configured to be at the same position in the circumferential direction. Of course, it is possible to adjust the inclination of the central axis of the lens 32 constituted by the optical element 10 by adjusting.

In the embodiment, the interface 28 between the first liquid 14 and the second liquid 16 is directed from the first liquid 14 to the second liquid 16 regardless of whether a voltage is applied to the first liquid 14. Therefore, the case where the lens 32 formed by the optical element 10 is a lens having a power for converging light, that is, a convex lens has been described.
However, the interface 28 between the first liquid 14 and the second liquid 16 has a convex curved surface shape from the second liquid 16 toward the first liquid 14 regardless of whether or not a voltage is applied to the first liquid 14. Therefore, even if the lens 32 formed by the optical element 10 has a power to diverge light, that is, a concave lens, image blur due to camera shake can be corrected.
12A and 12B are explanatory diagrams of image blur correction by the concave lens. FIG. 12A shows a state where the central axis of the concave lens and the optical axis of the photographing optical system 44 coincide with each other, and FIG. A state in which the photographing optical system 44 is moved in a predetermined direction within a plane orthogonal to the optical axis is shown.
That is, the photographing optical system 44 includes two lenses 44A and 44B, and the lens 32 is disposed between the two lenses 44A and 44B. Light 2 from the subject passes through the lens 44A, the lens 32, and the lens 44B. By passing, the light is converged and imaged on the image sensor 48.
Here, when the central axis of the lens 32 is moved in a predetermined direction within a plane orthogonal to the optical axis of the imaging optical system 44, the position of the subject image formed on the image sensor 48 is in a direction opposite to the predetermined direction. Moving.
Thus, even if the lens 32 formed by the optical element 10 is a concave lens, image blur correction can be performed. When the lens 32 is a concave lens, the first axis may be inclined by tilting the central axis of the lens 32 with respect to the optical axis of the photographing optical system 44 by the same configuration as the first and second embodiments. Image blur correction can be performed in the same manner as in the second embodiment.

  In the present embodiment, the case where the electrocapillary phenomenon is generated by applying a DC voltage to the first liquid 14 has been described. However, the voltage applied to the first liquid 14 is limited to the DC voltage. Instead, any voltage such as an AC voltage, a pulse voltage, or a voltage that increases or decreases in a stepwise manner may be used. In short, it is only necessary that the first liquid 14 can generate an electrocapillary phenomenon.

1 is a longitudinal sectional view showing a configuration of an optical element 10. It is AA sectional view taken on the line of FIG. 1 is a perspective view in which a part of an optical element 10 is omitted. (A), (B) is explanatory drawing of angle (theta) which the 1st liquid 14 and the water-repellent film 26 make. It is BB sectional drawing of FIG. It is a figure which shows the magnitude | size of the voltage E applied to each division body. 2 is a block diagram illustrating a configuration of an imaging device 40. FIG. 4A and 4B are explanatory diagrams of image blur correction by a lens 32, where FIG. 5A shows a state where image blur correction is not performed, and FIG. 5B shows a state where image blur correction is performed. It is sectional drawing which shows the structure of the optical element 10 of 2nd Embodiment. It is a top view of the 2nd electrode 20 in a 2nd embodiment. It is a figure which shows the magnitude | size of the voltage E applied to each division body 19. FIG. It is explanatory drawing of the correction | amendment of the image blur by a concave lens, (A) shows the state with which the center axis | shaft of a concave lens and the optical axis of the imaging optical system 44 correspond, (B) is a center optical axis of a concave lens. The state which moved to the predetermined direction within the surface orthogonal to the optical axis of 44 is shown. It is a principle explanatory view of an electrocapillary phenomenon, (A) is a figure showing the state before voltage application, and (B) is a figure showing the state after voltage application.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Optical element 12 ... Container 1202 ... 1st end surface wall 1204 ... 2nd end surface wall, 1206 ... Side wall, 14 ... 1st liquid 14 ... 2nd liquid, 18... First electrode, 20... Second electrode, 22... Split, 24 .. Insulating film, 26.

Claims (15)

A container having first and second end face walls facing each other in the thickness direction, and a side wall connecting the first and second end face walls, and a sealed storage chamber formed therein. When,
A polar or conductive first liquid sealed in the storage chamber;
A second liquid enclosed in the storage chamber and not mixed with the first liquid;
Voltage applying means for applying a voltage to the first liquid,
The voltage applying means includes a first electrode provided on the first end wall and at least a part of which is in contact with the first liquid, and a side wall surrounding the side wall facing the storage chamber. A second electrode extending along the direction and facing the second liquid,
By applying voltage by the voltage application means, the interface shape of the first liquid and the second liquid is deformed into a curved surface, and thus proceeds in the thickness direction of the container through the first and second end face walls. An optical element that refracts light passing through the interface,
The second electrode is composed of a plurality of divided bodies cut along the circumferential direction of the side wall,
An optical element. A container having first and second end face walls facing each other in the thickness direction, and a side wall connecting the first and second end face walls, and a sealed storage chamber formed therein. When,
A polar or conductive first liquid sealed in the storage chamber;
A second liquid enclosed in the storage chamber and not mixed with the first liquid;
Voltage applying means for applying a voltage to the first liquid,
The voltage applying means is provided on the first end face wall and is provided extending along the circumferential direction of the first end face wall so that at least a part thereof is in contact with the first liquid. 1 electrode and a second electrode provided along the circumferential direction of the side wall at the location of the side wall facing the storage chamber,
By applying voltage by the voltage application means, the interface shape of the first liquid and the second liquid is deformed into a curved surface, and thus proceeds in the thickness direction of the container through the first and second end face walls. An optical element that refracts light passing through the interface,
The first electrode is composed of a plurality of divided bodies cut along the circumferential direction of the first end wall.
An optical element.   The first liquid and the second liquid have substantially the same specific gravity, and the refractive index of the first liquid is higher than the refractive index of the second liquid. Item 3. The optical element according to Item 1 or 2.   The optical element according to claim 1, wherein an insulating film that covers the second electrode is provided.   An insulating film is provided to cover the second electrode, and a water-repellent film that covers the insulating film and has higher wettability with respect to the second liquid than the wettability with respect to the first liquid is provided. The optical element according to claim 1 or 2.   An insulating film is provided to cover the second electrode, and a water-repellent film that covers the insulating film and has higher wettability with respect to the second liquid than the wettability with respect to the first liquid is provided. In a state where no voltage is applied, the first liquid contacts the first electrode on the first end face wall, and a portion where the first liquid faces the side wall is the insulating film. And the second liquid is positioned on the second end wall and the second liquid faces the side wall through the water-repellent film. The optical element according to claim 1, wherein a portion is located on the water repellent film.   3. The voltage applying means is configured to apply a voltage whose value gradually changes along the direction in which the divided bodies are arranged to the plurality of divided bodies. Optical elements.   In a state where no voltage is applied to the plurality of divided bodies by the voltage application means, a central axis passing through the center of the interface shape passes through the centers of the first and second end face walls, and the voltage application means 3. The optical element according to claim 1, wherein the interface shape is deformed by applying a voltage such that the central axis is tilted.   The optical element according to claim 1, wherein the plurality of divided bodies have the same extension length extending in the circumferential direction.   3. The optical element according to claim 1, wherein the plurality of divided bodies have the same extension length extending in the circumferential direction, and 4N (N is a natural number) are provided.   The optical element according to claim 1, wherein the plurality of divided bodies have the same shape.   The interface between the first liquid and the second liquid maintains a convex curved shape from the first liquid toward the second liquid regardless of whether a voltage is applied to the first liquid. The optical element according to claim 1 or 2.   The interface between the first liquid and the second liquid maintains a convex curved shape from the second liquid toward the first liquid regardless of whether a voltage is applied to the first liquid. The optical element according to claim 1 or 2.   The first liquid has a portion that always faces the outer peripheral portion of the first end face wall regardless of a change in the shape of the interface, and the first liquid always faces the first liquid. The optical element according to claim 1, wherein the optical element is formed on an outer peripheral portion of the first end face wall.   The portion of the second liquid that faces the side wall moves due to a change in the shape of the interface, and the second electrode is formed over at least the portion of the side wall where the second liquid moves. The optical element according to claim 1.

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