JP4848961B2 - Optical element - Google Patents

Description

  The present invention relates to an optical element.

There has been proposed an optical element that changes an optical characteristic by changing an interface shape between the first and second liquids using an electrocapillary phenomenon (electrowetting phenomenon).
Such an optical element has first and second end face walls facing each other and a side wall connecting the first and second end face walls, and a sealed storage chamber is formed inside them. Equipped with a container.
Then, the first liquid having polarity or conductivity and the second liquid sealed in the storage chamber and not mixed with the first liquid are sealed in the storage chamber, and an electric field is applied to the first liquid. The interface shape between the first and second liquids is changed by providing a first electrode and a second electrode, and applying a voltage between the first electrode and the second electrode.
By the way, when such an optical element constitutes a diaphragm, when the aperture of the diaphragm is decentered, and when the optical element constitutes a lens, when the lens is decentered, the optical characteristics of the optical element Adversely affects.
In order to prevent the occurrence of such eccentricity, one of the first electrode and the second electrode of the optical element is divided into a plurality of electrode portions, and the voltage applied to each electrode portion is determined according to the amount of eccentricity. Techniques for controlling each have been proposed (see Patent Document 1).
JP 2003-177219 A

However, the above-described conventional technology requires a control circuit that applies different voltages to the plurality of electrode portions in accordance with the eccentricity of the optical element, so that the optical element can be simplified and reduced in cost. In addition, since the voltage applying means must apply different voltages to the respective electrode portions, it is disadvantageous in terms of reducing power consumption during operation of the voltage applying means.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an optical element that is advantageous in terms of simplification, cost reduction, and power consumption of the optical element while preventing the occurrence of eccentricity. There is to do.

In order to achieve the above-mentioned object, the present invention has first and second end face walls facing each other and side walls connecting the first and second end face walls, and is sealed inside them. a housing chamber are formed container, a first liquid having a polar or conductive encapsulated in yield vessel chamber, a second liquid not mixing with the first liquid are enclosed in yield vessel chamber, a first electrode and a second electrode for applying an electric field to the first liquid, and a voltage applying means for applying a voltage between the first electrode and the second electrode, transmission of the first liquid rates are formed lower than the transmittance of the second liquid, a voltage is applied by electrostatic application of pressure means to deform it et first liquid and the interface of the second liquid, Oyo first and second end walls the Ri through beauty second liquid portion 1, the transmission path of the light which the second end face wall extends in the thickness direction of the direction der Ru container facing each other form An optical element that is, the first electrode is formed on the inner surface of the extraordinary free first end face wall to yield volume chamber, the second electrode, the inner surface of the extraordinary free second end wall to yield vessel chamber is formed, the second electrode is formed of a plurality of electrode portions extending in radial direction around a single virtual axis extending in the thickness direction of the container, adjacent in the circumferential direction of the virtual axis the first non-electrode portion between the to that metal contacts not electrodes portion is formed is formed, and non-electrode portion of the electrode sections and the first is along the circumferential direction of the virtual axis a width of each of the electrode portions, the width of the hand electrodes part as the leading radially outwardly of a circle around the virtual axis is formed so as gradually increases, of the electrode portions a portion located outside are connected to each other, the non-electrode portion of the first is of form such that the width of the first non-electrode portions hand as the lead in the radius direction outwardly gradually decreases And wherein the are.
Moreover, this invention has the 1st, 2nd end surface wall which mutually faces, and the side wall which connects the 1st, 2nd end surface wall, and the container in which the sealed storage chamber was formed in those inside When a first liquid having a polar or conductive encapsulated in yield vessel chamber, a second liquid not mixing with the first liquid are enclosed in yield vessel chamber, an electric field to the first liquid And a voltage applying means for applying a voltage between the first electrode and the second electrode. The transmittance of the first liquid is that of the second liquid. formed lower than the transmittance, electric pressure application means to deform it et first liquid and the interface of the second liquid by applying a voltage by the first and second end walls and second liquid portions there an optical element in which the first Ri through the transmission path of light extending in the thickness direction of the direction der Ru container to the second end wall are opposed to each other are formed , The first electrode is formed on the inner surface of the extraordinary free first end face wall to yield volume chamber, the second electrode is formed on the inner surface of the extraordinary free second end wall to yield vessel chamber, the second electrode is composed of a plurality of electrode portions extending in radial direction around a single virtual axis extending in the thickness direction of the container, between you adjacent electrodes portion in the circumferential direction of the virtual axis the collector of the first non-electrode portions pole is not formed is formed on the non-electrode portion of the electrode sections and the first has a width along the circumferential direction of the virtual axis, respectively, each electrode portion is the portion where the width of the hand electrodes part as the leading radially outwardly of a circle around the virtual axis is formed so as gradually increases, located outside of the electrode portions is are connected to each other, the non-electrode portion of the first is characterized by having a uniform width along the radius direction.
Moreover, this invention has the 1st, 2nd end surface wall which mutually faces, and the side wall which connects the 1st, 2nd end surface wall, and the container in which the sealed storage chamber was formed in those inside When a first transparent liquid having a polar or conductive encapsulated in yield vessel chamber, and a second transparent liquid not mixing with the first liquid are enclosed in yield vessel chamber, first It includes a first electrode and a second electrode for applying an electric field to the liquid, and voltage application means for applying a voltage between the first electrode and the second electrode, whereby a voltage is applied by electrostatic application of pressure means by deforming the et first liquid and interface shape of the second liquid into a curved shape, a first, field surface proceeds in the thickness direction of the direction der Ru container to the second end wall are opposed to each other an optical element for refracting light passing through the first electrode is formed on the inner surface of the extraordinary free first end face wall to yield vessel chamber, the The electrode is formed on the inner surface of the extraordinary free second end wall to yield volume chamber, the second electrode, extending in a radial direction around a single virtual axis extending in the thickness direction of the container to be constituted by a plurality of electrode portions, the first non-electrode portions not electrodes portion is formed between the you adjacent electrodes portion in the circumferential direction of the virtual axis is formed, the electrode sections and non-electrode portion of the first has a width along the circumferential direction of the virtual axis, respectively, each electrode portion of the hand electrodes part as the leading radially outwardly of a circle around the virtual axis width is formed so as gradually increases, the radial portion located outside of the electrode portions are connected to each other, each of the first non-electrode portion, the hand first non as leading to half radially outward The electrode portion is formed so that the width is gradually reduced.
Moreover, this invention has the 1st, 2nd end surface wall which mutually faces, and the side wall which connects the 1st, 2nd end surface wall, and the container in which the sealed storage chamber was formed in those inside When a first transparent liquid having a polar or conductive encapsulated in yield vessel chamber, and a second transparent liquid not mixing with the first liquid are enclosed in yield vessel chamber, first It includes a first electrode and a second electrode for applying an electric field to the liquid, and voltage application means for applying a voltage between the first electrode and the second electrode, whereby a voltage is applied by electrostatic application of pressure means by deforming the et first liquid and interface shape of the second liquid into a curved shape, a first, field surface proceeds in the thickness direction of the direction der Ru container to the second end wall are opposed to each other an optical element for refracting light passing through the first electrode is formed on the inner surface of the extraordinary free first end face wall to yield vessel chamber, the The electrode is formed on the inner surface of the extraordinary free second end wall to yield volume chamber, the second electrode, extending in a radial direction around a single virtual axis extending in the thickness direction of the container to be constituted by a plurality of electrode portions, the first non-electrode portions not electrodes portion is formed between the you adjacent electrodes portion in the circumferential direction of the virtual axis is formed, the electrode sections and non-electrode portion of the first has a width along the circumferential direction of the virtual axis, respectively, each electrode portion of the hand electrodes part as the leading radially outwardly of a circle around the virtual axis width is formed so as gradually increases, the radial portion located outside of the electrode portions are connected to each other, the non-electrode portion of the first can have a uniform width along the radius direction It is characterized by being.

According to the optical element of the present invention, although the same voltage is applied to each electrode portion, the first liquid and the second liquid are positioned at a position where the center of the second liquid coincides with the virtual axis. Since the shape of the liquid interface is stable, the optical element is prevented from being decentered.
Therefore, it goes without saying that it is advantageous in preventing the optical characteristics of the optical element from degrading, and unlike the conventional optical element, the voltages applied to the plurality of electrode portions differ depending on the eccentricity of the light transmission path. This eliminates the need for a control circuit to be applied, which is advantageous for simplifying and reducing the cost of the optical element, and also for reducing power consumption.

(First embodiment)
First, the principle of the electrocapillary phenomenon (electrowetting phenomenon) used by the optical element of the present invention will be described.
1A and 1B are diagrams illustrating the principle of the electrocapillary phenomenon. FIG. 1A is a diagram illustrating a state before voltage application, and FIG. 1B is a diagram illustrating a state after voltage application.
As shown in FIG. 1A, an insulating film 2 is formed on the surface of the substrate 1, and a polar or conductive first liquid 3 is located on the surface of the insulating film 2, and the first The first electrode 4 is electrically connected to the liquid 3.
A second electrode 5 is formed between the insulating film 2 and the substrate 1.
As shown in FIG. 1A, when the voltage E is not applied between the first electrode 4 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 angle θ between the surface of the insulating film 2 and the portion where the first liquid 3 is in contact with the insulating film 2, that is, the contact angle θ is defined as θ 0. 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. 1B, when an electric field is applied to the first liquid 4 by applying a voltage E between the first electrode 4 and the second electrode 5, the insulating film 2. An electric field (electrostatic force) acts on the molecules constituting the first liquid 3 by, for example, charging a negative charge on the surface of the first liquid 3. As a result, the molecules constituting the first liquid 3 are attracted, so that the wettability of the first liquid 3 with respect to the insulating film 2 is improved, and the contact angle θ becomes 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.
In the present embodiment, the optical element 10 forms a diaphragm.
2 is a longitudinal sectional view showing the configuration of the optical element 10, FIG. 3 is a perspective view of the optical element 10, and FIG. 4 is a view taken along the line AA in FIG.
As shown in FIGS. 2 and 3, the optical element 10 includes a container 12, a first liquid 14, a second liquid 16, a first electrode 18, a second electrode 20, and voltage applying means. 22.
The container 12 includes a first end surface wall 24 and a second end surface wall 26 which face each other and extend in parallel, and a side wall 28 which connects the first and second end surface walls 24 and 26. The housing chamber 30 is hermetically sealed by the first and second end face walls 24 and 26 and the side wall 28.
Here, the thickness direction of the container 12 refers to a direction in which the first end face wall 24 and the second end face wall 26 face each other.
In the present embodiment, the first and second end face walls 24 and 26 have a rectangular plate shape having the same shape and the same size, and the side wall 28 has an outline of the first and second end face walls 24 and 26. It has a cylindrical wall shape that can be accommodated, and the storage chamber 30 has a flat columnar shape.
The first and second end face walls 24 and 26 and the side wall 28 are made of an insulating material, and the first and second end face walls 24 and 26 are made of a transparent material that transmits light. Is formed.
As a material constituting the first and second end face walls 24 and 26, 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 30.
The second liquid 16 is not mixed with the first liquid 14 and is enclosed in the storage chamber 30.
Further, the first liquid 14 and the second liquid 16 have substantially the same specific gravity, and the transmittance of the first liquid 14 is formed to be lower than the transmittance of the second liquid 16. .
In the present embodiment, the first liquid 14 is formed, for example, by mixing fine particles made of a material that does not transmit light with a liquid obtained by mixing pure water, ethanol, and ethylene glycol.
As the fine particles, for example, carbon black can be used. When carbon black is used, it is preferable to perform hydrophilic coating treatment on the surfaces of the carbon black so that the carbon black is uniformly mixed with the first liquid 14. The hydrophilic coating treatment is performed, for example, by forming a hydrophilic group on the surface of carbon black.
In the present embodiment, the second liquid 16 is composed of silicon oil.
The liquid that can be used as the first liquid 14 is not limited to the present embodiment. For example, 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, benzene Nitoru, aniline, 1,4-dioxane, hexamethylphosphoramide 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, it is sufficient that the first liquid 14 and the second liquid 16 are formed so as to have substantially the same specific gravity.

The first and second electrodes 18 and 20 are for applying an electric field to the first liquid 14.
The first electrode 18 is formed at a location where the first end wall 24 faces the storage chamber 30, and in the present embodiment, the first end wall 24 is formed over the entire inner surface facing the storage chamber 30.
More specifically, in this embodiment, as will be described later, the hydrophilic film 34 is used to increase the operating speed of the diaphragm, and the first electrode 18 faces the first liquid 14. The first electrode 18 is disposed so as to face the first liquid 14 through the hydrophilic film 34.
The second electrode 20 is formed on a part of the inner surface of the second end face wall 26 facing the accommodation chamber 30.
The first and second electrodes 18 and 20 are made of a conductive material such as an ITO film (Indium Tin Oxide film) that can transmit light.
The voltage application means 22 is provided outside the container 12, and the output voltage is variable. The positive voltage output terminal of the voltage application means 22 is electrically connected to the first electrode 18, and the voltage application means 22 outputs a negative voltage. A terminal is electrically connected to the second electrode 20.
In this embodiment, the case where the electrocapillarity is generated by applying a DC voltage to the first liquid 14 will be 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.

An insulating film 32 is formed on the inner surface of the second end face wall 26 facing the storage chamber 30 and the second electrode 20 provided on the inner surface.
Accordingly, when a voltage is applied to the first electrode 18 and the second electrode 20, for example, a negative charge is charged on the surface of the insulating film 32, whereby an electric field is applied to the first liquid 14, and the first liquid. 14 is configured such that an electric field (electrostatic force) acts on the molecules constituting 14 to generate an electrocapillary phenomenon.

Further, as shown in FIG. 2, a transparent hydrophilic film 34 that transmits light so as to cover the entire area of the first electrode 18 and the entire inner surface of the side wall 28 (corresponding to the first film in the claims). Is formed.
The hydrophilic film 34 is configured such that the wettability with respect to the first liquid 14 is higher than the wettability with respect to the second liquid 16. In other words, the contact angle of the first liquid 14 with respect to the hydrophilic film 34 is The contact angle of the second liquid 16 with respect to the hydrophilic film 34 is smaller than the contact angle.
The hydrophilic film 34 can be formed, for example, by applying a hydrophilic polymer or a surfactant to the inner surfaces of the first electrode 18 and the side wall 28, and various conventionally known materials can be employed.
Further, in the present embodiment, as shown in FIG. 2, a transparent repellent material that transmits light so as to cover the entire area of the insulating film 32 provided on the second electrode 20 on the second end wall 26. A water film 36 (corresponding to the second film in the claims) is formed.
The water repellent film 36 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. In other words, the contact angle of the second liquid 16 with respect to the water repellent film 36 is configured to be smaller than the contact angle of the first liquid 14 with respect to the water repellent film 36.
The water repellent film 36 is an oleophilic film, and can be formed, for example, by baking a material mainly composed of silicon or by forming a material made of an amorphous fluororesin. As the water film 36, various conventionally known materials can be used.
In FIG. 4, the hydrophilic film 34 and the water repellent film 36 are not shown.

Next, the second electrode 20 will be described in detail.
As shown in FIG. 4, the second electrode 20 includes a plurality of electrodes extending in the radial direction around a single virtual axis 38 extending in the thickness direction of the container 12 (see FIGS. 2 and 3). The unit 40 is configured.
In the present embodiment, the second electrode 20 is composed of four electrode portions 40 having the same shape and the same size, and portions 4002 located on the outer sides in the radial direction of the electrode portions 40 are connected to each other. Therefore, the voltage applied to the second electrode 20 by the voltage applying means 22, that is, the voltage applied to each electrode portion 40 is the same voltage.
A first non-electrode part 42 in which no electrode part 40 is formed is formed between the electrode parts 40 adjacent in the circumferential direction of the virtual axis 38.
In the present embodiment, four first non-electrode portions 42 having the same shape and the same size are formed.
Each electrode portion 40 and each first non-electrode portion 42 have a width along the circumferential direction of the virtual axis 38, and each electrode portion 40 is radially outward of a circle centering on the virtual axis 38. The width of the electrode part 40 is formed so as to gradually increase, and each first non-electrode part 42 is formed so that the width of the first non-electrode part 42 gradually decreases toward the outside in the radial direction. ing.
Further, the width of the electrode portion 40 is always larger than the width of the first non-electrode portion 42 on a single circumference centered on the virtual axis 38.
In the present embodiment, each electrode portion 40 extends in a fan shape radially outward with the virtual axis 38 as the center, and each first non-electrode portion 42 gradually decreases in width as it extends radially outward. The tip of the first non-electrode part 42 is located on a single virtual circle centered on the virtual axis 38.
In the present embodiment, the second non-electrode portion 44 in which the electrode portion 40 is not formed is provided in a substantially circular range centered on the virtual axis 38.
Each electrode portion 40 is provided on the outer side in the radial direction of the second non-electrode portion 44, and the inner edge portion in the radial direction of each electrode portion 40 extends on a single virtual circle centered on the virtual axis 38. is doing.
Each first non-electrode portion 42 is provided so as to protrude from the outer peripheral portion spaced in the circumferential direction of the second non-electrode portion 44 to the outer side in the radial direction of the second non-electrode portion 44. The non-electrode part 42 is connected to the outer peripheral part of the second non-electrode part 44.
Therefore, the arc portion 40 </ b> A is formed at the boundary between the inner peripheral portion of each electrode portion 40 and the outer peripheral portion of the second non-electrode portion 44.

Therefore, as shown in FIG. 2, the entire area of the first liquid 14 located on the inner surface of the first end wall 24 where the first liquid 14 is located faces the first electrode 18 via the hydrophilic film 34. The entire region of the second liquid 16 located on the inner surface of the second end face wall 26 where the second liquid 16 is located is in contact with the second electrode via the water repellent film 36 and the insulating film 32. It will be in the state which faced 20.
Therefore, the voltage V is applied from the voltage applying means 22 to the first electrode 18 and the second electrode 20, for example, a negative charge is charged on the surface of the insulating film 32, thereby applying an electric field to the first liquid 14, An electric field (electrostatic force) acts on the molecules constituting the first liquid 14 to generate an electrocapillary phenomenon.

Next, the operation of the optical element 10 will be described.
FIGS. 5A, 5 </ b> B, and 5 </ b> C are cross-sectional views illustrating operations when voltages V <b> 1, V <b> 2, and V <b> 3 are applied to the first and second electrodes 18 and 20 of the optical element 10.
As shown in FIG. 2, in the state where the voltage V is not applied from the voltage applying means 22 to the first electrode 18 and the second electrode 20, the shape of the interface 48 between the first and second liquids 14 and 16 is the first. It is determined by the balance between the surface tension of the second liquids 14 and 16 and the interfacial tension on the water repellent film 36.
Therefore, the larger the difference between the contact angle of the first liquid 14 with respect to the water repellent film 36 and the contact angle of the second liquid 16, the more flat the second liquid 16 spreads on the water repellent film 36. The shape of the interface 48 between the liquid 14 and the second liquid 16 is a curved surface close to a flat surface.
The first liquid 14 is positioned so as to cover the hydrophilic film 34 on the side wall 28 from the hydrophilic film 34 on the first end wall 24.
Therefore, the first liquid 14 located in an annular portion near the interface between the side wall 28 and the second end wall 26 in the first liquid 14 directly contacts the water repellent film 36, but the second liquid 16 Is not in contact with the hydrophilic film 34 on the side wall 28.
Therefore, the annular portion where the first liquid 14 is in contact with the water repellent film 36 faces the second electrode 20 with the water repellent film 36 and the insulating film 32 interposed therebetween without the second liquid 16 interposed. Yes.
At this time, the first liquid 14 extends over the entire region in the direction orthogonal to the light transmission direction, so that the light traveling in the thickness direction of the container 12 is blocked.

Next, as shown in FIG. 5A, when the voltage V1 (> 0) is applied from the voltage applying means 22 to the first electrode 18 and the second electrode 20, the interface 48 is caused by the electrocapillary phenomenon. The second liquid 16 is deformed so as to have a convex curved surface (spherical surface) toward the first liquid 14, and the center of the interface 48 contacts the first end wall 24 (hydrophilic film 34).
As a result, the first liquid 14 does not exist in the region where the interface 48 is in contact with the first end wall 24 (hydrophilic film 34), and only the second liquid 16 exists in the storage chamber 30. A region 50 is formed, and a light transmission path 52 that extends in the thickness direction of the container 12 through the first and second end face walls 24 and 26 is formed by the region 50. That is, the light transmission path 52 forms the opening 52A, and the diameter of the light transmission path 52 (opening 52A) is the aperture diameter D1 of the diaphragm.

Next, as shown in FIG. 5B, when a voltage V2 (> V1) is applied from the voltage applying means 22 to the first electrode 18 and the second electrode 20, a convex curved surface ( The slope of the (spherical) curve is further increased.
And the diameter of the area | region 50 in which only the 2nd liquid 16 formed in the storage chamber 30 exists is expanded, and the diameter of the light transmission path 52, ie, the aperture diameter of a diaphragm, is expanded from D1 to D2.

Next, as shown in FIG. 5C, when a voltage V3 (> V2) is applied from the voltage application means 22 to the first electrode 18 and the second electrode 20, a convex curved surface ( The slope of the (spherical) curve is further increased.
Then, the diameter of the region 50 where only the second liquid 16 is formed in the storage chamber 30 is further expanded, and the diameter of the light transmission path 52, that is, the aperture diameter of the diaphragm is the maximum value D3 (> D2). The diameter is expanded.
Therefore, by adjusting the voltage applied from the voltage application means 22 to the first electrode 18 and the second electrode 20, the diameter of the region 50 where only the second liquid 16 exists is enlarged and reduced to reduce the aperture. The opening diameter can be adjusted.
5A, 5B, and 5C, reference numerals θ1, θ2, and θ3 indicate contact angles of the first liquid 14, and the larger the electric field applied to the first liquid 14, the more the contact is made. The corners are reduced and the wettability of the first liquid 14 is increased.

Although the hydrophilic film 34 and the water repellent film 36 can be omitted, the use of the hydrophilic film 34 and the water repellent film 36 as in the present embodiment has the following advantages.
When a transparent hydrophilic film 34 (corresponding to the first film) that transmits light is formed so as to cover the entire area of the first electrode 18 and the entire inner surface of the side wall 28, the first liquid 14 is hydrophilic. The film 34 gets wet well. Therefore, when the second liquid 16 once contacts the first end face wall 24 and then leaves the first end face wall 24, the second liquid 16 is easily separated from the hydrophilic film 34, and the operation speed of the diaphragm is reduced. Speeding up.
Further, when a transparent water-repellent film 36 that transmits light is formed so as to cover the entire region of the insulating film 32 provided on the second electrode 20 on the second end face wall 26, the water-repellent film Since the liquid level of the first liquid 14 is likely to move smoothly on 36, the operating speed of the diaphragm can be increased.

Next, a change in the shape of the interface 48 between the first liquid 14 and the second liquid 16 will be described in detail.
When a voltage V is applied between the first electrode 18 and the second electrode 20, as shown in FIGS. 5A to 5C, the interface 48 between the first liquid 14 and the second liquid 16. Is the contact angle θ, the contact angle θ is expressed by equation (1).
cosθ (V) = cosθ (V = 0) + ε0 ・ εr ・ V2 / 2γt (1)
Here, cosθ (V) is the contact angle when the applied voltage is V [V], cosθ (V = 0) is the contact angle when no voltage is applied, and ε0 is the dielectric constant of vacuum 8.85 × 10-12 [F / m , Εr is the relative dielectric constant of the insulating film 32, V is the applied voltage [V], t is the thickness [m] of the insulating film 32, and γ is the interfacial tension between the first liquid 14 and the second liquid 16 (or Interfacial energy) [N / m].
That is, the contact angle θ is increased or decreased by the increase or decrease of the voltage V (the wettability of the first liquid 14 is changed), and thereby the force with which the first liquid 14 pushes the second liquid 16 is changed. The shape changes.

Next, the change in the shape of the interface 48 between the first liquid 14 and the second liquid 16 described above will be described in more detail.
First, as shown in FIG. 5A, a case where a voltage V1 (> 0) is applied from the voltage application means 22 to the first electrode 18 and the second electrode 20 will be described.
FIG. 6 is a plan view of FIG. 5A, in which the one-dot chain line indicates the interface 48a on the first end face wall 24 (hydrophilic film 34), and the two-dot chain line indicates the second end face wall 26 ( The interface 48b on the water repellent film 36) is shown.
FIG. 7 is a perspective view schematically showing the shape of the second liquid 16 in FIG.
As shown in FIGS. 6 and 7, the interface 48 a on the first end wall 24 has a substantially circular shape with the virtual axis 38 as the center.
On the second end face wall 26, the interface 48 b includes four arcuate portions 48 b 1 extending on the circumference located on the outer side in the radial direction of the second non-electrode portion 44 centering on the virtual axis 38. The adjacent arc-shaped portions 48b1 are connected to each other, and four projecting portions 48b2 projecting radially outward from the circumference of the arc-shaped portions 48b1.

Next, the case where the voltage V2 (> V1) is applied from the voltage application means 22 to the first electrode 18 and the second electrode 20 as shown in FIG. 5B will be described in detail.
FIG. 8 is a perspective view schematically showing the shape of the second liquid 16 in FIG.
As shown in FIG. 8, when the second liquid 16 is pushed by the first liquid 14, the diameter of the interface 48 a on the first end face wall 24 is enlarged, and the interface 48 b on the second end face wall 26 is expanded. Retreats to a position close to the contours of the first and second non-electrode portions 42 and 44.

Next, the case where the voltage V3 (> V2) is applied to the first electrode 18 and the second electrode 20 from the voltage applying means 22 as shown in FIG. 5C will be described in detail.
FIG. 9 is a plan view of FIG.
As shown in FIG. 9, the second liquid 16 is further pushed by the first liquid 14, whereby the diameter of the interface 48 a on the first end face wall 24 is expanded to the maximum, and the first end face wall 24 is The interface 48b in FIG. 4 retreats to a position that matches the contours of the first and second non-electrode portions 42 and 44.
At this time, the second liquid 16 extends over the entire area of the first and second non-electrode portions 42 and 44 on the second end face wall 26.
Accordingly, the second liquid 16 has four arms extending from the outer periphery of the portion located on the second non-electrode portion 44 along the first non-electrode portion 42 to the radius of the second non-electrode portion 44. It will protrude outward in the direction. Therefore, the outer periphery of the central portion of the second liquid 16 (portion positioned on the second electrode portion 42) is pulled by these four arm portions and deformed.
As a result, the shape of the interface 48a on the first end face wall 24 is substantially rectangular with four corners positioned on each first non-electrode portion 42.

Thus, the first liquid 14 moves and pushes the second liquid 16 by changing the contact angle (the wettability of the first liquid 14) according to the voltage applied thereto. Therefore, on the second end face wall 26, the interface 48 moves only on the electrode portion 40 to which a voltage is applied, and does not move on the first and second non-electrode portions 42 and 44 to which no voltage is applied. .
In other words, the second liquid 16 is always located on the first and second non-electrode portions 42 and 44 on the second end face wall 26, and the second liquid 16 is the first liquid 16. As the liquid 14 moves outward in the radial direction of the second non-electrode portion 44, the liquid 14 moves so as to spread from the first and second non-electrode portions 42 and 44 onto the electrode portion 40.

As described above, when the voltage applied between the first electrode 18 and the second electrode 20 is increased or decreased from V1 to V3, the shape of the interface 48 changes and the opening diameter changes from D1 to D3. Regardless of the change in the voltage applied between the electrode 18 and the second electrode 20, the light transmission path 52 (opening 52A) shown in FIG. Even if the center of the light transmission path 52 is deviated from the virtual axis 38 and is decentered, the center of the light transmission path 52 is automatically restored so as to coincide with the virtual axis 38. This will be described in detail.
10 is an explanatory view showing a state where the center of the light transmission path 52 is coincident with the virtual axis 38, and FIG. 11 is an explanatory view showing a state where the center of the light transmission path 52 is deviated from the virtual axis 38, FIG. FIG. 12 is a perspective view of FIG. 11.
10, 11, and 12, for convenience of explanation, the insulating film 32 that is orthogonal to the virtual axis 38 is divided by two coordinate axes X and Y that are orthogonal to the virtual axis 38 and orthogonal to each other. The four quadrants will be described as a first quadrant A, a second quadrant B, a third quadrant C, and a fourth quadrant D.
Each electrode unit 40 is located in each of the first quadrant A, the second quadrant B, the third quadrant C, and the fourth quadrant D.

As shown in FIG. 10, in the state where the light transmission path 52 (see FIG. 5) is not decentered, the areas of the first liquids 14 positioned on the electrode portions 40 are equal to each other, and The areas of the second liquid 16 located on the electrode unit 40 are equal to each other. In other words, the length of the interface 48b1 between the first liquid 14 and the second liquid 16 located on each electrode portion 40 is equal to each other.
However, as shown in FIGS. 11 and 12, for example, when the second liquid 16 moves in the direction of the second quadrant B and the light transmission path 52 is decentered, the electrode portion of the second quadrant B is formed. The length of the interface 48b1 located on the 40 is not equal to the length of the interface 48b1 located on the electrode portion 40 in the fourth quadrant D.
Specifically, the length of the interface 48b1 located on the electrode part 40 in the second quadrant B is longer than the length of the interface 48b1 located on the electrode part 40 in the fourth quadrant D. .
This is because each electrode portion 40 and each first non-electrode portion 42 have a width along the circumferential direction of the virtual axis 38, and each electrode portion 40 is in the radial direction of a circle centering on the virtual axis 38. The width of the electrode portion 40 is formed so as to gradually increase toward the outer side, and each first non-electrode portion 42 is formed so that the width of the first non-electrode portion 42 gradually decreases toward the outer side in the radial direction. This is because it is formed.
Therefore, if the voltage applied to each electrode part 40 is the same (if it is the same potential), the force per unit length with which the first liquid 14 pushes the second liquid 16 is the same in each quadrant. Since the length of the interface 48b1 positioned on the electrode portion 40 is increased, the force pushing the second liquid 16 increases in proportion to the length of the interface 48b1, and the force pushing the second liquid 16 is The second quadrant B works larger than the fourth quadrant D.
Therefore, since the length of the interface 48b1 on the electrode part 40 in the fourth quadrant D is longer than the length of the interface 48b1 on the electrode part 40 in the second quadrant B, the first on the second quadrant B is obtained. The force with which the liquid 14 pushes the second liquid 16 is greater than the force with which the first liquid 14 in the fourth quadrant D pushes the second liquid 16.
As a result, the second liquid 16 is pushed back until the force that pushes the second liquid 16 is balanced by the first liquid 14, that is, as shown in FIG. 10, the length of the interface 48b1 in the second quadrant B is increased. And the second liquid 16 is pushed back until the length of the interface 48b1 in the fourth quadrant D becomes equal. As a result, the center of the second liquid 16 and the virtual axis 38 coincide with each other. At this position, the shape of the interface 48 between the first liquid 14 and the second liquid 16 is stabilized, and the light transmission path 52 is decentered. Is prevented.

Further, as shown in FIG. 8, the second liquid 16 has a second arm with four arms extending from the outer periphery of the portion located on the second non-electrode part 44 along the first non-electrode part 42. In other words, the four arms are formed by the second liquid 16 remaining on the first non-electrode portions 42.
Therefore, the outer periphery of the central portion of the second liquid 16 (the portion located on the second electrode portion 42) is in a state of being pulled by these four arm portions, and thereby the second liquid 16 Is always urged so that its central portion coincides with the virtual axis 38.
Therefore, as shown in FIG. 12, when the second liquid 16 moves in the direction of the second quadrant B and the central portion of the second liquid 16 is eccentric from the virtual axis 38, the central portion of the second liquid 16 The balance of the forces due to the four arm portions acting is lost, and the forces due to the four arm portions act in the direction in which the center of the second liquid 16 and the virtual axis 38 coincide.
By this action, the second liquid 16 is reliably restored by the position where the center and the virtual axis 38 coincide with each other, and the shape of the interface 48 between the first liquid 14 and the second liquid 16 is more stable at this position. In addition, the prevention of the eccentricity of the light transmission path 52 is more effectively realized.
The action of the four arm portions with respect to the central portion of the second liquid 16 described above can be described as follows, for example.
That is, when the skin of the drum drum is fastened, it is necessary to match the center of the skin with the central axis of the drum.
At this time, if several places of the skin located in the circumferential direction of the central axis of the trunk are temporarily fixed to the trunk, and these several places are pulled toward the outside of the trunk little by little, the center of the skin is aligned with the central axis of the trunk. Can be easily adapted to.
Similarly, the center of the second liquid 16 is easily aligned with the virtual axis 38 by applying a force in the radially outward direction to the second liquid 16 by the four arm portions. Can be made.
In addition, when the voltage applied between the first electrode 18 and the second electrode 20 is increased or decreased while the second liquid 16 remains on each first non-electrode portion 42, the second liquid Since 16 moves along the four arm portions, it is advantageous to move the second liquid 16 uniformly and smoothly over the circumferential direction of the circle centered on the virtual axis 38.

The optical element 10 described above is applied to a photographing optical system of an imaging apparatus such as a digital still camera or a video camera.
FIG. 13 is a configuration diagram illustrating an example in which the optical element 10 is applied to a photographing optical system of an imaging apparatus.
As illustrated in FIG. 13, the imaging apparatus 100 includes an imaging element 102 such as a CCD that captures a subject image, and a photographing optical system 104 that guides the subject image to the imaging element 102.
On the optical axis L, the photographic optical system 104 has a first lens group 106, a second lens group 108, a third lens group 110, a fourth lens group 112, from the subject toward the image sensor 102, The filter group 114 is arranged in this order.
In this example, the first lens group 106 and the third lens group 110 are provided so as not to move in the optical axis direction, and the second lens group 108 is provided as a zoom lens so as to be movable in the optical axis direction. The fourth lens group 112 is provided as a focus lens so as to be movable in the optical axis direction.
The light beam from the subject guided by the first lens group 106 is converted into a parallel light beam by the second lens group 108 and guided to the third lens group 110, via the fourth lens group 112 and the filter group 114. And converged on the imaging surface 102 of the imaging element 102.
The optical element 10 is disposed between the second lens group 108 and the third lens group 110 where the parallel luminous flux passes with the virtual axis 38 aligned with the optical axis L of the photographing optical system 104. Has been.
Therefore, the light transmission path 52 (opening 52A) of the optical element 10 expands and contracts, whereby the amount of light guided to the imaging surface 102A is increased or decreased.
Strictly speaking, the force of the electric field applied to the first liquid 14 is not uniform in the circumferential direction of the virtual axis 38 because the first non-electrode part 42 is provided between the plurality of electrode parts 40. Therefore, since the interface 48 between the first liquid 14 and the second liquid 16 is not uniform in the circumferential direction of the virtual axis 38, the shape of the light transmission path 52 (opening 52A) of the optical element 10 is also a perfect circle. Rather, the radial dimension varies along the circumferential direction.
However, as described above, since the stop is disposed at a position where the light beams are parallel, the influence of the shape of the opening 52A on the optical characteristics can be ignored.

As described above, according to the present embodiment, each electrode portion 40 and each first non-electrode portion 42 of the optical element 10 have a width along the circumferential direction of the virtual axis 38, and each electrode The portion 40 is formed so that the width of the electrode portion 40 gradually increases as it goes radially outward of the circle centered on the virtual axis 38, and each first non-electrode portion 42 reaches radially outward. Accordingly, the width of the first non-electrode portion 42 is formed so as to be gradually reduced, so that the center of the second liquid 16 is applied even though the same voltage is applied to each electrode portion 40. Since the shape of the interface 48 between the first liquid 14 and the second liquid 16 is stabilized at the position where the virtual axis 38 and the virtual axis 38 coincide with each other, the eccentricity of the light transmission path 52 (opening 52A) is prevented.
Accordingly, it goes without saying that it is advantageous in preventing the deterioration of the optical characteristics due to the aberration caused by the decentration of the light transmission path 52 of the optical element 10 and the occurrence of shading due to the nonuniformity of the peripheral light amount. As described above, since a control circuit for applying different voltages to the plurality of electrode portions 40 according to the eccentricity of the light transmission path is not required, the optical element 10 can be simplified and reduced in cost. In addition, the voltage applying means 22 only has to apply the same voltage to each electrode section 40, which is advantageous in reducing the power consumption during operation of the voltage applying means 22.

(Second Embodiment)
Next, a second embodiment will be described.
FIG. 14 is a plan view of the second electrode 20 in the second embodiment. In the following embodiments, the same or similar parts and members as those in the first embodiment will be described with the same reference numerals.
The second embodiment is different from the first embodiment in that the second electrode 20 is constituted by three electrode portions 40 and the first non-electrode portion 42 is three.
That is, as shown in FIG. 14, the second electrode 20 includes three electrode portions 40 having the same shape and the same size, and the portions 4002 positioned on the outer sides in the radial direction of the electrode portions 40 are connected to each other.
A first non-electrode part 42 in which no electrode part 40 is formed is formed between the electrode parts 40 adjacent in the circumferential direction of the virtual axis 38.
In the present embodiment, three first non-electrode portions 42 having the same shape and the same size are formed.
The second electrode 20 is composed of three electrode portions 40, the first non-electrode portion 42 is three, and the first non-electrode portion 42 is composed of three first non-electrode portions 42. This is the same as the embodiment.
In the second embodiment, the same effect as that of the first embodiment can be obtained.

(Third embodiment)
Next, a third embodiment will be described.
FIG. 15 is a plan view of the second electrode 20 in the third embodiment.
The third embodiment is different from the first embodiment in that the second electrode 20 is composed of six electrode portions 40 and the number of first non-electrode portions 42 is six.
That is, as shown in FIG. 15, the second electrode 20 is composed of six electrode portions 40 having the same shape and the same size, and portions 4002 located on the outer sides in the radial direction of the electrode portions 40 are connected to each other.
A first non-electrode part 42 in which no electrode part 40 is formed is formed between the electrode parts 40 adjacent in the circumferential direction of the virtual axis 38.
In the present embodiment, six first non-electrode portions 42 having the same shape and the same size are formed.
The configuration of the second electrode 20 is the same as that of the first embodiment except that the second electrode 20 includes six electrode portions 40 and the first non-electrode portion 42 includes six.
In the third embodiment, the same effect as that of the first embodiment can be obtained.
Further, in the third embodiment, the number of the electrode portions 40 and the first non-electrode portions 42 is larger than that in the first embodiment, so that the second portion in the circumferential direction of the circle centered on the virtual axis 38 is used. The bias of the electric field applied to one liquid 14 is made more uniform, and therefore the interface 48 between the first liquid 14 and the second liquid 16 is also made uniform in the circumferential direction. There is an advantage that the shape of the transmission path 52 (opening 52A) becomes a shape closer to a perfect circle.

(Fourth embodiment)
Next, a fourth embodiment will be described.
FIG. 16 is a plan view of the second electrode 20 in the fourth embodiment.
The fourth embodiment is different from the first embodiment in that the second electrode 20 is composed of eight electrode portions 40 and the first non-electrode portion 42 is eight.
That is, as shown in FIG. 16, the second electrode 20 is composed of eight electrode portions 40 having the same shape and the same size, and the portions 4002 located on the outer sides in the radial direction of the electrode portions 40 are connected to each other.
A first non-electrode part 42 in which no electrode part 40 is formed is formed between the electrode parts 40 adjacent in the circumferential direction of the virtual axis 38.
In the present embodiment, eight first non-electrode portions 42 having the same shape and the same size are formed.
The configuration of the second electrode 20 is the same as that of the first embodiment, except that the second electrode 20 includes eight electrode portions 40 and the first non-electrode portion 42 includes eight.
In the fourth embodiment, the same effect as that of the first embodiment can be obtained.
In the fourth embodiment, the number of the electrode portions 40 and the first non-electrode portions 42 is larger than that in the third embodiment. The bias of the electric field applied to one liquid 14 is made more uniform, and therefore the interface 48 between the first liquid 14 and the second liquid 16 is also made uniform in the circumferential direction. There is an advantage that the shape of the transmission path 52 (opening 52A) becomes a shape closer to a perfect circle.

(Fifth embodiment)
Next, a fifth embodiment will be described.
FIG. 17 is a plan view of the second electrode 20 in the fifth embodiment.
In the fifth embodiment, the shape of the electrode part 40 constituting the second electrode 20 and the shape of the first non-electrode part 42 are different from those in the fourth embodiment.
That is, as shown in FIG. 4, the shape of the first non-electrode portion 42 is an isosceles triangle in the fourth embodiment, whereas it is almost an equilateral triangle in the fifth embodiment. Yes.
Corresponding to this, the shape of the electrode part 40 located between the adjacent first non-electrode parts 42, that is, the shape of the sector forming the electrode part 40 is also different.
The configuration other than the shape of the electrode part 40 constituting the second electrode 20 and the shape of the first non-electrode part 42 is the same as that of the first embodiment.
In the fifth embodiment, the same effect as that of the first embodiment can be obtained.

(Sixth embodiment)
Next, a sixth embodiment will be described.
FIG. 18 is a plan view of the second electrode 20 in the sixth embodiment.
In the sixth embodiment, the shape of the tip of the first non-electrode portion 42 (the outer end in the radial direction centered on the virtual axis 38) is different from that of the fourth embodiment.
That is, as shown in FIG. 18, the tip of each electrode portion 40 has an arc shape so as to be positioned on a single circumference centered on the virtual axis 38.
The configuration other than the shape of the tip of the electrode unit 40 is the same as that of the first embodiment.
In the sixth embodiment, the same effect as that of the first embodiment can be obtained.

(Seventh embodiment)
Next, a seventh embodiment will be described.
FIG. 19 is a plan view of the second electrode 20 in the seventh embodiment.
The seventh embodiment is different from the first embodiment in that the first non-electrode portion 42 is provided so as to be continuous with the outer peripheral portion of the second non-electrode portion 44.
That is, in the seventh embodiment, the arc portion 40A (see FIG. 14) is not formed at the boundary between the inner peripheral portion of each electrode portion 40 and the outer peripheral portion of the second non-electrode portion 44. The non-electrode portion 42 is provided so as to be continuous with the outer peripheral portion of the second non-electrode portion 44. Therefore, the inner peripheral part of each electrode part 40 is formed with a convex angle in the direction of the virtual axis 38.
Moreover, the point which the 2nd electrode 20 is comprised by the five electrode parts 40, and the 1st non-electrode part 42 is five differs from 1st Embodiment.
Other configurations are the same as those in the first embodiment.
In the seventh embodiment, the same effect as that of the first embodiment can be obtained.

(Eighth embodiment)
Next, an eighth embodiment will be described.
FIG. 20 is a plan view of the second electrode 20 in the eighth embodiment.
As shown in FIG. 20, the second electrode 20 includes a plurality of electrodes extending in the radial direction around a single virtual axis 38 extending in the thickness direction of the container 12 (see FIGS. 2 and 3). The unit 40 is configured.
In the present embodiment, the second electrode 20 is composed of six electrode portions 40 having the same shape and size, and the portions 4002 located on the outer sides in the radial direction of the electrode portions 40 are connected to each other. Therefore, the voltage applied to the second electrode 20 by the voltage applying means 22, that is, the voltage applied to each electrode portion 40 is the same voltage.
A first non-electrode part 42 in which no electrode part 40 is formed is formed between the electrode parts 40 adjacent in the circumferential direction of the virtual axis 38.
In the present embodiment, six first non-electrode portions 42 having the same shape and the same size are formed.
Each electrode portion 40 and each first non-electrode portion 42 have a width along the circumferential direction of the virtual axis 38, and each electrode portion 40 is radially outward of a circle centering on the virtual axis 38. As a result, the width of the electrode portion 40 is gradually increased, and each first non-electrode portion 42 has a uniform width along the radial direction.
Further, the width of the electrode portion 40 is always larger than the width of the first non-electrode portion 42 on a single circumference centered on the virtual axis 38.
In the present embodiment, each electrode portion 40 extends in a fan shape radially outward with the virtual axis 38 as the center, and the tip of the first non-electrode portion 42 has a single center around the virtual axis 38. Located on a virtual circle.
In the present embodiment, the second non-electrode portion 44 in which the electrode portion 40 is not formed is provided in a substantially circular range centered on the virtual axis 38.
Each electrode portion 40 is provided on the outer side in the radial direction of the second non-electrode portion 44, and the inner edge portion in the radial direction of each electrode portion 40 extends on a single virtual circle centered on the virtual axis 38. is doing.
Each first non-electrode portion 42 is provided so as to protrude from the outer peripheral portion spaced in the circumferential direction of the second non-electrode portion 44 to the outer side in the radial direction of the second non-electrode portion 44. The non-electrode part 42 is connected to the outer peripheral part of the second non-electrode part 44.
Therefore, the arc portion 40 </ b> A is formed at the boundary between the inner peripheral portion of each electrode portion 40 and the outer peripheral portion of the second non-electrode portion 44.
In the eighth embodiment, the same effect as that of the first embodiment is achieved.

(Ninth embodiment)
Next, a ninth embodiment will be described.
21 is a longitudinal sectional view showing the configuration of the optical element 10 according to the ninth embodiment, and FIG. 22 is a view taken along the line AA in FIG.
The ninth embodiment is different from the first to eighth embodiments in that the optical element 10 constitutes a lens.
The configuration of the optical element 10 of the ninth embodiment is substantially the same as that of the first embodiment except that the compositions of the first and second liquids 14 and 16 are different. Differences from the first embodiment will be described.
The optical element 10 deforms the shape of the interface 48 between the first liquid 14 and the second liquid 16 into a curved surface by applying a voltage from the voltage applying unit 22, so that the first and second end face walls 24 and 26 are formed. The light travels in the thickness direction of the container 12, which faces each other, and refracts light passing through the interface 48.
As shown in FIGS. 21 and 22, the optical element 10 includes a container 12, a first liquid 14, a second liquid 16, a first electrode 18, as in the first embodiment. The second electrode 20 and the voltage applying means 22 are included.
The first liquid 14 has polarity or conductivity and is enclosed in the storage chamber 30.
The second liquid 16 is not mixed with the first liquid 14 and is enclosed in the storage chamber 30.
The first liquid 14 and the second liquid 16 are transparent and have substantially the same specific gravity, and the refractive index of the second liquid 16 is formed higher than the refractive index of the first liquid 14. .
The shape and arrangement of the first electrode 18 and the second electrode 20 are the same as in the first embodiment.
That is, as shown in FIG. 22, the second electrode 20 has a plurality of electrode portions extending in the radial direction around a single virtual axis 38 extending in the thickness direction of the container 12 (see FIG. 20). 40.
A first non-electrode part 42 in which no electrode part 40 is formed is formed between the electrode parts 40 adjacent in the circumferential direction of the virtual axis 38.
In the present embodiment, four first non-electrode portions 42 having the same shape and the same size are formed.
Each electrode portion 40 and each first non-electrode portion 42 have a width along the circumferential direction of the virtual axis 38, and each electrode portion 40 is radially outward of a circle centering on the virtual axis 38. The width of the electrode part 40 is formed so as to gradually increase, and each first non-electrode part 42 is formed so that the width of the first non-electrode part 42 gradually decreases toward the outside in the radial direction. ing.
Further, the width of the electrode portion 40 is always larger than the width of the first non-electrode portion 42 on a single circumference centered on the virtual axis 38.
In the present embodiment, each electrode portion 40 extends in a fan shape radially outward with the virtual axis 38 as the center, and each first non-electrode portion 42 gradually decreases in width as it extends radially outward. The tip of the first non-electrode part 42 is located on a single virtual circle centered on the virtual axis 38.
In the present embodiment, the second non-electrode portion 44 in which the electrode portion 40 is not formed is provided in a substantially circular range centered on the virtual axis 38.
Each electrode portion 40 is provided on the outer side in the radial direction of the second non-electrode portion 44, and the inner edge portion in the radial direction of each electrode portion 40 extends on a single virtual circle centered on the virtual axis 38. is doing.
Each first non-electrode portion 42 is provided so as to protrude from the outer peripheral portion spaced in the circumferential direction of the second non-electrode portion 44 to the outer side in the radial direction of the second non-electrode portion 44. The non-electrode part 42 is connected to the outer peripheral part of the second non-electrode part 44.
Therefore, the arc portion 40 </ b> A is formed at the boundary between the inner peripheral portion of each electrode portion 40 and the outer peripheral portion of the second non-electrode portion 44.
In FIG. 22, a two-dot chain line indicates an interface 48 (48b, 48b1, 48b2) on the second end face wall 26, as in FIG. 6 showing the first embodiment.

Next, the operation of the optical element 10 will be described.
23A, 23B, and 23C are cross-sectional views for explaining the operation when the voltages V1, V2, and V3 are applied to the first and second electrodes 18 and 20 of the optical element 10. FIG.
As shown in FIG. 21, when the voltage V is not applied from the voltage applying means 22 to the first electrode 18 and the second electrode 20, the shape of the interface 48 between the first and second liquids 14 and 16 is the first. , Which is determined by the balance between the surface tension of the second liquids 14 and 16 and the interfacial tension on the water repellent film 36, and forms a gently convex curved surface from the second liquid 16 toward the first liquid 14. .
Here, since the refractive index of the second liquid 16 is higher than the refractive index of the first liquid 14, it passes through the first and second end face walls 24, 26 in the thickness direction of the container 12. The light traveling and passing through the interface 48 is refracted at the interface 48, and therefore the optical element 10 constitutes a lens having a power for converging the light.

Next, as shown in FIG. 23A, when the voltage V1 (> 0) is applied from the voltage applying means 22 to the first electrode 18 and the second electrode 20, the interface 48 is affected by the electrocapillary phenomenon. The inclination of the curved curved surface (spherical surface) becomes large.
Next, as shown in FIG. 23B, when a voltage V2 (> V1) is applied from the voltage application means 22 to the first electrode 18 and the second electrode 20, a convex curved surface ( The slope of the (spherical) curve is further increased.
Next, as shown in FIG. 23C, when a voltage V3 (> V2) is applied from the voltage applying means 22 to the first electrode 18 and the second electrode 20, a convex curved surface ( The slope of the (spherical) curve is further increased.
Therefore, by adjusting the voltage applied from the voltage application means 22 to the first electrode 18 and the second electrode 20, the focal length of the lens can be varied by changing the curvature of the interface 48 (the lens power can be varied). ).
As in the first embodiment, the optical element 10 constituting the lens can be applied to an imaging optical system of an imaging apparatus such as a digital still camera or a video camera.

In the optical element 10, when the voltage applied between the first electrode 18 and the second electrode 20 is increased or decreased from V1 to V3, the shape of the interface 48 changes and the focal length of the lens changes. Regardless of the change in voltage applied between the first electrode 18 and the second electrode 20, the lens always keeps its center coincident with the virtual axis 38, and the center of the lens is the virtual axis. Even if the lens is deviated from the position 38 and decentered, the center of the lens is automatically restored so as to coincide with the virtual axis 38.
That is, as in the first embodiment, each electrode portion 40 and each first non-electrode portion 42 of the optical element 10 have a width along the circumferential direction of the virtual axis 38, and each electrode portion 40. Is formed such that the width of the electrode portion 40 gradually increases as it goes outward in the radial direction of the circle centered on the virtual axis 38, and each first non-electrode portion 42 has a first width as it goes outward in the radial direction. Since the width of one non-electrode portion 42 is formed so as to be gradually reduced, the center of the second liquid 16 and the virtual position are virtually not affected even though the same voltage is applied to each electrode portion 40. Since the shape of the interface 48 between the first liquid 14 and the second liquid 16 is stabilized at the position where the shaft 38 is coincident, decentering of the lens is prevented.
Similarly to the first embodiment, the second liquid 16 includes four arms from the outer periphery of the portion located on the second non-electrode portion 44 along each first non-electrode portion 42. Protrudes radially outward of the second non-electrode portion 44, so that the outer periphery of the central portion of the second liquid 16 (the portion located on the second electrode portion 42) The second liquid 16 is constantly urged so that the central portion thereof coincides with the virtual axis 38, and thus acts on the central portion of the second liquid 16. The forces by the four arm portions act in the direction in which the center of the second liquid 16 and the virtual axis 38 coincide.
By this action, the second liquid 16 is reliably restored by the position where the center and the virtual axis 38 coincide with each other, and the shape of the interface 48 between the first liquid 14 and the second liquid 16 is more stable at this position. In addition, prevention of lens decentration is more effectively realized.
Accordingly, in the ninth embodiment, as in the first embodiment, it is of course advantageous to prevent the optical characteristics of the optical element 10 from being deteriorated, and is eccentric as in the conventional optical element. Accordingly, a control circuit for applying different voltages to the plurality of electrode portions 40 is not required, which is advantageous in simplifying and reducing the cost of the optical element 10, and voltage applying means. Since it is only necessary to apply the same voltage to each electrode section 40, the power supply 22 is advantageous in reducing the power consumption during the operation of the voltage applying means 22.

  In the ninth embodiment, the case where the second electrode 20 of the optical element 10 is configured similarly to the first embodiment has been described. However, the configuration of the second electrode 20 is the second configuration. Of course, it may be configured similarly to the eighth embodiment.

It is a principle explanatory view of electrocapillary phenomenon, (A) is a figure showing the state before voltage application, and (B) is a figure showing the state after voltage application. 1 is a longitudinal sectional view showing a configuration of an optical element 10. 1 is a perspective view of an optical element 10. FIG. FIG. 3 is a view taken along line AA in FIG. 2. (A), (B), (C) is sectional drawing explaining operation | movement when voltage V1, V2, V3 is applied to the 1st, 2nd electrodes 18 and 20 of the optical element 10. FIG. FIG. 6 is a plan view of FIG. FIG. 6 is a perspective view schematically showing the shape of the second liquid 16 in FIG. FIG. 8 is a perspective view schematically showing the shape of the second liquid 16 in FIG. FIG. 6 is a plan view of FIG. FIG. 6 is an explanatory view showing a state where the center of a light transmission path 52 is coincident with a virtual axis 38; FIG. 6 is an explanatory view showing a state where the center of the light transmission path 52 is deviated from the virtual axis 38 and decentered. FIG. 12 is a perspective view of FIG. 11. It is a block diagram which shows the example which applied the optical element 10 to the imaging optical system of an imaging device. It is a top view of the 2nd electrode 20 in a 2nd embodiment. It is a top view of the 2nd electrode 20 in a 3rd embodiment. It is a top view of the 2nd electrode 20 in a 4th embodiment. It is a top view of the 2nd electrode 20 in a 5th embodiment. It is a top view of the 2nd electrode 20 in a 6th embodiment. It is a top view of the 2nd electrode 20 in a 7th embodiment. It is a top view of the 2nd electrode 20 in an 8th embodiment. It is a longitudinal cross-sectional view which shows the structure of the optical element 10 in 9th Embodiment. 22 is a view taken along the line AA in FIG. (A), (B), (C) is sectional drawing explaining operation | movement when voltage V1, V2, V3 is applied to the 1st, 2nd electrodes 18 and 20 of the optical element 10. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Optical element, 12 ... Container, 14 ... 1st liquid, 16 ... 2nd liquid, 18 ... 1st electrode, 20 ... 2nd electrode, 22 ... Voltage application means, 24 …… First end face wall, 26 …… Second end face wall, 28 …… Side wall, 30 …… Accommodating chamber, 38 …… Virtual axis, 40 …… Electrode portion, 42 …… First non-electrode Part, 48 ... interface.

Claims (9)

A container having first and second end face walls facing each other and a side wall connecting the first and second end face walls, and a sealed storage chamber formed therein;
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;
A first electrode and a second electrode for applying an electric field to the first liquid;
Voltage applying means for applying a voltage between the first electrode and the second electrode,
The transmittance of the first liquid is formed lower than the transmittance of the second liquid,
By applying voltage by the voltage applying means, the interface between the first liquid and the second liquid is deformed, passes through the first and second end face walls and the second liquid portion, and the first and second liquids. An optical element in which a light transmission path extending in the thickness direction of the container, which is a direction in which end walls face each other, is formed,
The first electrode is formed on an inner surface of the first end face wall facing the storage chamber,
The second electrode is formed on the inner surface of the second end wall facing the storage chamber,
The second electrode is composed of a plurality of electrode portions extending in the radial direction around a single virtual axis extending in the thickness direction of the container,
A first non-electrode part in which the electrode part is not formed is formed between the electrode parts adjacent in the circumferential direction of the virtual axis,
The electrode portions and the first non-electrode portions each have a width along the circumferential direction of the virtual axis,
Each electrode part is formed such that the width of the electrode part gradually increases as it goes radially outward of a circle centered on the virtual axis,
The portions located outside the radial direction of the electrode portions are connected to each other,
Each of the first non-electrode portions is formed such that the width of the first non-electrode portion gradually decreases as it goes outward in the radial direction.
An optical element. A container having first and second end face walls facing each other and a side wall connecting the first and second end face walls, and a sealed storage chamber formed therein;
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;
A first electrode and a second electrode for applying an electric field to the first liquid;
Voltage applying means for applying a voltage between the first electrode and the second electrode,
The transmittance of the first liquid is formed lower than the transmittance of the second liquid,
By applying voltage by the voltage applying means, the interface between the first liquid and the second liquid is deformed, passes through the first and second end face walls and the second liquid portion, and the first and second liquids. An optical element in which a light transmission path extending in the thickness direction of the container, which is a direction in which end walls face each other, is formed,
The first electrode is formed on an inner surface of the first end face wall facing the storage chamber,
The second electrode is formed on the inner surface of the second end wall facing the storage chamber,
The second electrode is composed of a plurality of electrode portions extending in the radial direction around a single virtual axis extending in the thickness direction of the container,
A first non-electrode part in which the electrode part is not formed is formed between the electrode parts adjacent in the circumferential direction of the virtual axis,
The electrode portions and the first non-electrode portions each have a width along the circumferential direction of the virtual axis,
Each electrode part is formed such that the width of the electrode part gradually increases as it goes radially outward of a circle centered on the virtual axis,
The portions located outside the radial direction of the electrode portions are connected to each other,
Each of the first non-electrode portions has a uniform width along the radial direction.
An optical element. A container having first and second end face walls facing each other and a side wall connecting the first and second end face walls, and a sealed storage chamber formed therein;
A transparent first liquid having polarity or conductivity enclosed in the storage chamber;
A transparent second liquid enclosed in the storage chamber and not mixed with the first liquid;
A first electrode and a second electrode for applying an electric field to the first liquid;
Voltage applying means for applying a voltage between the first electrode and the second electrode,
By deforming the interface shape of the first liquid and the second liquid into a curved surface by applying a voltage by the voltage applying means, the first and second end face walls are in a direction facing each other. An optical element that refracts light traveling in the thickness direction and passing through the interface,
The first electrode is formed on an inner surface of the first end face wall facing the storage chamber,
The second electrode is formed on the inner surface of the second end wall facing the storage chamber,
The second electrode is composed of a plurality of electrode portions extending in the radial direction around a single virtual axis extending in the thickness direction of the container,
A first non-electrode part in which the electrode part is not formed is formed between the electrode parts adjacent in the circumferential direction of the virtual axis,
The electrode portions and the first non-electrode portions each have a width along the circumferential direction of the virtual axis,
Each electrode part is formed such that the width of the electrode part gradually increases as it goes radially outward of a circle centered on the virtual axis,
The portions located outside the radial direction of the electrode portions are connected to each other,
Each of the first non-electrode portions is formed such that the width of the first non-electrode portion gradually decreases as it goes outward in the radial direction.
An optical element. A container having first and second end face walls facing each other and a side wall connecting the first and second end face walls, and a sealed storage chamber formed therein;
A transparent first liquid having polarity or conductivity enclosed in the storage chamber;
A transparent second liquid enclosed in the storage chamber and not mixed with the first liquid;
A first electrode and a second electrode for applying an electric field to the first liquid;
Voltage applying means for applying a voltage between the first electrode and the second electrode,
By deforming the interface shape of the first liquid and the second liquid into a curved surface by applying a voltage by the voltage applying means, the first and second end face walls are in a direction facing each other. An optical element that refracts light traveling in the thickness direction and passing through the interface,
The first electrode is formed on an inner surface of the first end face wall facing the storage chamber,
The second electrode is formed on the inner surface of the second end wall facing the storage chamber,
The second electrode is composed of a plurality of electrode portions extending in the radial direction around a single virtual axis extending in the thickness direction of the container,
A first non-electrode part in which the electrode part is not formed is formed between the electrode parts adjacent in the circumferential direction of the virtual axis,
The electrode portions and the first non-electrode portions each have a width along the circumferential direction of the virtual axis,
Each electrode part is formed such that the width of the electrode part gradually increases as it goes radially outward of a circle centered on the virtual axis,
The portions located outside the radial direction of the electrode portions are connected to each other,
Each of the first non-electrode portions has a uniform width along the radial direction.
An optical element. A second non-electrode part in which the electrode part is not formed is provided in a substantially circular range centering on the virtual axis, and each electrode part is provided outside the second non-electrode part in the radial direction. ing,
The optical element according to any one of claims 1 to 4, characterized in that. A second non-electrode part in which the electrode part is not formed is provided in a substantially circular range centering on the virtual axis, and each electrode part is provided outside the second non-electrode part in the radial direction. ,
Each of the first non-electrode portions is connected to an outer peripheral portion of the second non-electrode portion,
The optical element according to any one of claims 1 to 4, characterized in that. Wherein the electrode portions are similar in size and shape, the optical according to any one of the non-electrode portion of the first can claims 1, characterized in that it is similar in size and shape 4 element. The electrode portions are formed in the same shape and size, and the first non-electrode portions are formed in the same shape and size.
The width of the electrode portion is always larger than the width of the first non-electrode portion on a single circumference centered on the virtual axis.
The optical element according to any one of claims 1 to 4, characterized in that. Each of the electrode portions has the same shape and the same size, and extends in a fan shape radially outward from the virtual axis.
Each of the first non-electrode portions has the same shape and the same size, and extends in an isosceles triangle shape whose width gradually decreases toward the outer side in the radial direction,
The tip of the first non-electrode part is located on a single virtual circle centered on the virtual axis,
The optical element according to claim 1 or 3, characterized in that.

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