JP2006053433A - Optical element, lens unit and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element maintaining light transmissibility over a long term, a lens unit, and an imaging apparatus. <P>SOLUTION: Insulating liquid and conductive liquid having a different refractive index each other, liquated each other and respectively having the light transmissibility, are stored in a liquid container constituted of plastic through which gas is transmitted. Furthermore, the optical element is equipped with a 1st electrode coming into contact with the conductive liquid and a 2nd electrode insulated from the conductive liquid, and the shape of a boundary surface between the conductive liquid and the insulating liquid is changed by applying voltage having a reverse polarity to each other to the 1st electrode and the 2nd electrode. At such a time, the gas generated by electrolyzing the conductive liquid comes off to the outside of the plastic liquid container, so that the light transmissibility is maintained over a long term. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical element that transmits light, a lens unit, and an imaging device that forms image of subject light to acquire image data.

  In an electronic still camera that forms an image of a subject on a solid-state image sensor such as a charge coupled device (CCD) and captures image data representing the subject as a signal, or a film camera that takes a photograph on a photographic film Some cameras have a zoom function for freely setting a shooting angle of view, and such a camera is provided with a photographing lens whose focal length changes in accordance with the operation of a zoom switch. This photographing lens is generally a compound lens composed of a combination of a plurality of lens elements, and the relative positions of the plurality of lens elements are adjusted according to the focal length set by the zoom switch. Such a camera is equipped with a cam mechanism, and the cam mechanism transmits the rotation of the motor in response to the operation of the zoom switch, so that the plurality of lens elements move back and forth in the optical axis direction and the relative positions are adjusted. And the focal length changes.

  In addition, there is a focus lens for focus adjustment among the plurality of lens elements, and a lens driving mechanism for moving the focus lens may be provided separately from the cam mechanism.

  In recent years, in place of the above-described photographic lens having a drive mechanism, a variable focal length liquid lens in which two kinds of liquids having different refractive indexes and immiscible with each other is housed has been proposed (for example, Non-Patent Document 1).

  In the liquid lens proposed in Non-Patent Document 1, two kinds of liquids having different refractive indexes and immiscible with each other are accommodated inside, and one of these two kinds of liquids is A conductive aqueous solution and the other liquid is an insulating oil. These two kinds of liquids are accommodated in a liquid container in which both ends of a short glass tube are closed with a transparent end cap having light permeability. The inner wall of the tube and the inner wall of one end cap are covered with a water repellent film. According to the liquid lens thus configured, the conductive aqueous solution of the two types of liquid repels the inner wall of the tube covered with the water-repellent film and the inner wall of one end cap. Since the aqueous solution stays in a hemispherical shape in contact with the other end cap, the interface portion between the conductive aqueous solution and the insulating oil functions as a concave lens. The liquid lens is also provided with two electrodes for applying a voltage to the conductive aqueous solution, and one of the two electrodes is disposed in contact with the conductive aqueous solution. The other electrode is disposed on the back side of the water-repellent film. When a voltage is applied to such an electrode, an electric charge is released from the electrode disposed so as to be in contact with the aqueous conductive solution into the aqueous conductive solution, and the released charge is insulated in the aqueous conductive solution. Phenomenon that accumulates at the interface with the oil. The electric charge accumulated in the interface portion and the electric charge collected on the electrode disposed on the back side of the water-repellent film having a polarity opposite to that of the electric charge are attracted by the Coulomb force, so that the charge in the conductive aqueous solution is transferred to the water-repellent film. Attracted nearby. As a result, the conductive aqueous solution begins to wet the water-repellent film coated on the inner wall of the tube, and the interface shape of the two types of liquid changes. That is, as the voltage is applied to the conductive aqueous solution, the radius of curvature of the interface portion of the conductive aqueous solution that initially functioned as the concave lens with the insulating oil changes. The focal length is adjusted by flattening or the conductive aqueous solution functioning as a convex lens.

According to such a liquid lens, since the focal length can be changed without moving the lens, the zoom function and the focus function can be realized without providing the cam mechanism or the lens driving mechanism described above. . Therefore, the apparatus can be significantly reduced in size, and can be applied to a small device such as a mobile phone.
"Philips' Fluid Lenses", [online], March 3, 2004, Royal Philips Electronics, [March 31, 2004 search], Internet <URL: http: // www. dpreview. com / news / 0403/040030302 philipsfluidens. asp>

  However, according to the liquid lens described in Non-Patent Document 1, since the conductive aqueous solution is electrolyzed by the electric charge discharged from the electrode, the generated gas accumulates in the liquid container when used for a long time. As a result, there is a problem that bubbles are formed, light scattering occurs, and the light transmittance decreases.

  In view of the above circumstances, an object of the present invention is to provide an optical element, a lens unit, and an imaging device that can maintain light transmission over a long period of time.

The optical element of the present invention that achieves the above object includes an insulating liquid that has different refractive indexes, is immiscible with each other, has optical transparency, and a conductive liquid that generates gas when energized. A liquid container that is made of plastic that is permeable to gas and that transmits light at least in a predetermined optical axis direction;
A first electrode in contact with the conductive liquid in the liquid container;
And a second electrode insulated from the conductive liquid in the liquid container.

  According to the optical element of the present invention, when a voltage is applied between the first electrode and the second electrode, electric charges are discharged from the first electrode into the conductive liquid, and the second electrode Collects charges of the opposite polarity. As a result, the electric charge in the conductive liquid and the electric charge collected on the second electrode are attracted by the Coulomb force, and the shape of the boundary surface between the conductive liquid and the insulating liquid changes. At this time, the conductive liquid is electrolyzed by the electric charge discharged from the first electrode and the gas is generated. However, since the liquid container is made of plastic, the generated gas is It will escape from the liquid container, light scattering is avoided, and light transmission is maintained over a long period of time. Moreover, since the optical container of the present invention is made of plastic, the liquid container has high impact resistance and light weight compared to the case of using glass.

  In the optical element of the present invention, it is preferable that the liquid container is made of a plastic made of a bicyclic aliphatic monomer.

  When the liquid container is made of a plastic made of a bicyclic aliphatic monomer, an optical element that is light in weight and excellent in light transmission and impact resistance can be realized.

  In the optical element of the present invention, the liquid container may have at least a part of the inner surface covered with a coating film that has lower wettability with respect to the conductive liquid than wettability with respect to the insulating liquid. preferable.

  By providing such a coating film, the shape of the boundary surface between the conductive liquid and the insulating liquid is efficiently changed.

In the optical element of the present invention, the conductive liquid is an aqueous solution, and the insulating liquid is oil.
It is preferable that at least a part of the inner surface of the liquid container is covered with a coating film formed by water repellent treatment with a fluorine-based silane coupling agent.

  The coating film that has been subjected to water repellency treatment with a fluorine-based silane coupling agent has strong water repellency, so that the conductive liquid that is an aqueous solution repels the coating film, and the boundary surface between the conductive liquid and the insulating liquid. The shape of will change greatly.

  In the optical element of the present invention, it is preferable that an antireflection film for preventing light reflection is provided on the outer surface of the liquid container intersecting with the optical axis direction.

  By providing the antireflection film, the light transmittance is improved.

  In the optical element of the present invention, it is preferable that the antireflection film is composed of a fluorine-based polymer.

  By applying an antireflection film made of a fluorine-based polymer, a problem that dust or dirt adheres to the antireflection film is avoided, and high light transmittance is maintained.

  In the optical element of the present invention, it is also preferable that the antireflection film is formed by laminating silica and a polymer on the outer surface.

  According to a preferred embodiment of the optical element of the present invention, the effect of preventing light reflection is high and the light transmittance is high.

In addition, the lens unit of the present invention that achieves the above object includes an insulating liquid that has a refractive index different from each other, is immiscible with each other, has optical transparency, and a conductive liquid that generates gas when energized. A liquid container that is made of a plastic that is gas permeable and that transmits light at least in a predetermined optical axis direction;
A first electrode in contact with the conductive liquid in the liquid container;
A second electrode insulated against the conductive liquid in the liquid container,
The shape of the boundary surface between the insulating liquid and the conductive liquid changes according to the voltage applied between the first electrode and the second electrode.

  According to the lens unit of the present invention, light transmittance can be maintained over a long period of time as in the optical element of the present invention.

  Note that the lens unit according to the present invention is only shown in its basic form here, but this is only for avoiding duplication, and the lens unit according to the present invention is not limited to the above basic form. Various forms corresponding to the respective forms of the optical element described above are included.

In addition, the imaging device of the present invention that achieves the above object includes an insulating liquid having different refractive indexes, immiscible with each other, each having light permeability, and a conductive liquid that generates gas when energized. A liquid container made of plastic which is contained in the gas and transmits gas, and which transmits light at least in a predetermined optical axis direction;
A first electrode in contact with the conductive liquid in the liquid container;
A second electrode insulated from the conductive liquid in the liquid container;
A controller that changes the shape of the boundary surface between the insulating liquid and the conductive liquid by applying a voltage between the first electrode and the second electrode;
An imaging device that includes an insulating liquid and subject light that has passed through the conductive liquid is imaged on the surface to generate an image signal representing the subject light.

  According to the imaging apparatus of the present invention, light transmission can be maintained over a long period of time as in the optical element of the present invention.

  Note that only the basic form of the imaging apparatus according to the present invention is shown here, but this is only for avoiding duplication, and the imaging apparatus according to the present invention is not limited to the above basic form. Various forms corresponding to the respective forms of the optical element described above are included.

  ADVANTAGE OF THE INVENTION According to this invention, the optical element, lens unit, and imaging device which can maintain the light transmittance for a long term can be provided.

  Hereinafter, prior to describing embodiments of the present invention, the problems of the liquid lens described in Non-Patent Document 1 described above will be analyzed in detail.

  FIG. 1 is a schematic configuration diagram of a liquid lens as a comparative example. Hereinafter, light is transmitted in the direction of the arrow O, and the light incident side (upper side in FIG. 1) is referred to as the upper side, and the light emission side (lower side in FIG. 1) is referred to as the lower side.

  As shown in FIG. 1, the liquid lens 1 is made of transparent water in which a supporting electrolyte is added into a glass container 11 in which both ends of a glass tube 11a are closed with glass caps 11b and 11c. 21 and transparent oil 22 that is an insulating liquid are contained without being mixed with each other. Since the oil 22 has a higher light refractive index than the water 21, the oil 22 plays the role of a lens that refracts light in the liquid lens 1.

  The inner surface of the tube 11a of the container 11 and the inner surface of the cap 11b that closes the upper end of the tube 11a are covered with a water-repellent water-repellent film 15, and the inner surface of the cap 11c that closes the lower end of the tube 11a is hydrophilic. It is covered with a hydrophilic film 16 having

  Further, an insulating film 14 is provided between the tube 11 a and the water repellent film 15, and the liquid lens 1 is insulated from the water 21 by the first electrode 12 in contact with the water 21 and the insulating film 14. A second electrode 13 is also provided.

When no voltage is applied between the first electrode 12 and the second electrode 13, the water 21 repels the water-repellent film 15 and repels the hydrophilic film 16 as shown in part (A) of FIG. Therefore, the contact portion P ₁ between the water 21 and the water repellent film 15 becomes small. For this reason, the water 21 stays in a hemispherical shape, and the oil 22 pushed by the water 21 stays in a shape that penetrates the hemisphere from the cylindrical shape. Since the shape of the boundary surface between the water 21 and the oil 22 when viewed from the oil 22 is concave, in the part (A), the liquid lens 1 functions as a concave lens.

For example, when a positive voltage is applied to the first electrode 12 and a negative voltage is applied to the second electrode 13, a positive charge 31 a is released from the first electrode 12 to the water 21, and a negative voltage is applied to the second electrode 13. Charge 31b accumulates. At this time, the positive charge 31a released to the water 21 is attracted to the negative charge 31b of the second electrode 13 by the Coulomb force, and the contact portion P ₂ between the water 21 and the water repellent film 15 becomes larger according to the applied voltage. . In part (B), the shape of the boundary surface between the water 21 and the oil 22 when viewed from the oil 22 is convex, and the liquid lens 1 functions as a convex lens. Moreover, the shape of the boundary surface between the water 21 and the oil 22 can be changed little by little by adjusting the voltage applied to the first electrode 12 and the second electrode 13.

  Thus, according to the liquid lens 1, the zoom function and the focus function can be realized by changing the shape of the boundary surface between the water 21 and the oil 22 without providing a mechanism for moving the lens.

  Here, in the liquid lens 1, the water 21 is electrolyzed by the positive charge 31 a emitted from the first electrode 12 and gas is generated. Since the glass container 11 is impermeable to gas, the gas accumulates over a long period of time, and bubbles are generated in the water 21 or oil 22, and the light scattering is caused by the bubbles and the light transmittance is deteriorated. There is a problem that it ends up.

  In addition, the liquid lens 1 is considered to be applied to a small device such as a mobile phone. However, the glass container 11 is easily damaged due to an impact when the mobile phone is dropped or the like. Inconvenient liquid leaks.

  The present invention is based on the detailed analysis as described above.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 2 is an external perspective view of a digital camera to which an embodiment of the present invention is applied as seen from diagonally above the front.

  As shown in FIG. 2, a photographing lens 101 is provided at the center of the front surface of the digital camera 100. Further, an optical viewfinder objective window 102 and an auxiliary light emitting unit 103 are provided on the upper front of the digital camera 100. Further, a slide-type power switch 104 and a release switch 150 are provided on the upper surface of the digital camera 100.

  FIG. 3 is a schematic configuration diagram of the digital camera 100 shown in FIG.

  As shown in FIG. 3, the breakdown of the digital camera 100 is roughly divided into a photographing optical system 110 and a signal processing unit 120. In addition to these, the digital camera 100 includes an image display unit 130 for displaying captured images, an external recording medium 140 for recording captured image signals, and various processes for capturing digital cameras. A zoom switch 170, a shooting mode switch 160, and a release switch 150 are provided.

  First, the configuration of the photographing optical system 110 will be described with reference to FIG.

  In the digital camera 100, subject light enters from the left side of FIG. 3, passes through the zoom lens 115 and the focus lens 114, passes through the iris 113 that adjusts the amount of the subject light, and then is solid when the shutter 112 is open. An image is formed on the image sensor 111. The solid-state image sensor 111 corresponds to an example of an image sensor according to the present invention. Originally, a plurality of lenses are provided in the photographing optical system, and at least one of the plurality of lenses is largely involved in the focus adjustment, and the relative position of each lens is involved in the focal length. A lens related to the adjustment of the focal length is schematically shown as a zoom lens 115, and a lens related to the adjustment of the focus is also shown schematically as a focus lens 114.

  The zoom lens 115, the iris 113, and the shutter 112 are driven and moved by the zoom motor 115a, the iris motor 113a, and the shutter motor 112a, respectively. The focus lens 114 is provided with a focus controller 114a that changes the lens shape of the focus lens 114 instead of the motor. Instructions for operating the zoom motor 115a, the iris motor 113a, and the shutter motor 112a are transmitted from the digital signal processing unit 120b in the signal processing unit 120 through the motor driver 120c, and instructions for operating the focus controller 114a are digital. Directly transmitted from the signal processing unit 120b.

  The zoom lens 115 is moved in the direction along the optical axis by the zoom motor 115a. When the zoom lens 115 is moved to a position corresponding to the signal from the signal processing unit 120, the focal length is changed and the photographing magnification is determined.

  The focus lens 114 is a lens for realizing a TTLAF function. The TTLAF function generally detects the contrast of an image signal obtained by the solid-state imaging device 111 by the AF / AE calculation unit 126 of the signal processing unit 120 while moving the focus lens in a direction along the optical axis. The focus lens 114 is adjusted to the focus position with the lens position where the contrast peak is obtained as the focus position. With this TTLAF function, it is possible to automatically focus on a subject whose contrast is at a peak (that is, the closest subject closest to the subject). In this embodiment, instead of moving the focus lens 114, the focus controller 114a changes the lens shape of the focus lens 114 to focus the subject. The configuration of the focus lens 114 and the method of changing the lens shape will be described in detail later.

  The iris 113 is driven based on an instruction given from the AF / AE calculation unit 126 of the digital signal processing unit 120b to adjust the amount of subject light.

  The above is the configuration of the photographing optical system 110.

  Next, the configuration of the signal processing unit 120 will be described. A subject image formed on the solid-state imaging device 111 by the photographing optical system is read as an image signal to the analog processing (A / D) unit 120a, and the analog processing unit (A / D) 120a converts the analog signal into a digital signal. It is converted and supplied to the digital signal processor 120b. A system controller 121 is provided in the digital signal processing unit 120b, and signal processing in the digital signal processing unit 120b is performed in accordance with a program showing an operation procedure in the system controller 121. Data between the system controller 121 and the image signal processing unit 122, image display control unit 123, image compression unit 124, media controller 125, AF / AE calculation unit 126, key controller 127, buffer memory 128, and internal memory 129 Is transferred via the bus 1200, and the internal memory 129 serves as a buffer when data is transferred via the bus 1200. Data serving as variables is written to the internal memory 129 as needed according to the progress of the processing process of each unit, and the system controller 121, the image signal processing unit 122, the image display control unit 123, the image compression unit 124, and the media controller 125 are written. The AF / AE calculation unit 126 and the key controller 127 perform appropriate processing by referring to the data. That is, an instruction from the system controller 121 is transmitted to each of the above units via the bus 1200, and a processing process of each unit is started. Then, the data in the internal memory 129 is rewritten in accordance with the progress of the process, and is further referred to on the system controller 121 side to manage the operation of each unit described above. In other words, the power is turned on, and the process of each unit is started according to the procedure of the program in the system controller 121. For example, when the release switch 150, zoom switch, and shooting mode switch are operated, information indicating that the switch has been operated is transmitted to the system controller 121 via the key controller 127, and processing corresponding to the operation is performed by the system controller. This is performed according to the program procedure in 121.

  When the release operation is performed, the image data read from the solid-state imaging device is converted from an analog signal to a digital signal by an analog processing (A / D) unit 120a, and the digitized image data is converted into a digital signal processing unit. Once stored in the buffer memory 128 in 120b. The RGB signal of the digitized image data is converted into a YC signal by the image signal processing unit 122, and further compression called JPEG compression is performed by the image compression unit 124 so that the image signal becomes an image file and the media controller 125 is set. To the external recording medium 140. The image data recorded as the image file is reproduced on the image display unit 130 through the image display control unit 123. In this processing, the AF / AE calculation unit performs the focus adjustment and the exposure adjustment based on the RGB signals. The AF / AE calculation unit 126 detects the contrast for each subject distance from the RGB signals for focus adjustment. Based on the detection result, focus adjustment is performed by the focus lens 114. The AF / AE calculation unit extracts a luminance signal from the RGB signal, and detects the field luminance therefrom. Based on this result, exposure adjustment is performed by the iris 113 so that the amount of subject light given to the solid-state imaging device is appropriate.

  The digital camera 100 is basically configured as described above.

  Here, the feature of the present invention in the digital camera 100 is the focus lens 114. Hereinafter, the focus lens 114 will be described in detail.

  FIG. 4 is a schematic configuration diagram of the focus lens. The object light enters from the left side of FIG. 4 in the direction of arrow O, and the light incident side (left side of FIG. 4) is referred to as the front side, and the light emission side (right side of FIG. 4) is referred to as the rear side. I do.

  The focus lens 114 contains a conductive liquid 301 and an insulating liquid 302 immiscible with the conductive liquid 301 in a liquid container 201 in which both ends of the plastic tube 201a are closed with plastic substrates 201b and 201c. Is formed.

  First, the liquid container 201 will be described.

  The liquid container 201 has a light transmittance higher than that of glass of 90% or more such as ZEONOR (manufactured by Nippon Zeon Co., Ltd., a trade name of a plastic made of a bicyclic aliphatic monomer), and transmits gas. Consists of plastic. The liquid container 201 corresponds to an example of the liquid container referred to in the present invention.

  The surface (inner surface) of the plastic substrate 201c that closes the rear end of the plastic tube 201a that is in contact with the liquid is covered with a hydrophilic film 206 having hydrophilicity. Further, the inner surface of the liquid container 201 other than the portion covered with the hydrophilic film 206 is covered with a hydrophobic water-repellent film 205. The water repellent film 205 corresponds to an example of a coating film according to the present invention.

  An antireflection film 207 for preventing light reflection is provided on the surface (outer surface) opposite to the surface in contact with the liquid of the plastic substrates 201b and 201c. The antireflection film 207 corresponds to an example of the antireflection film according to the present invention.

As a procedure for forming the liquid container 201, for example, plasma processing is performed at 0.1 w / cm ² for 10 minutes in a vacuum container having an oxygen partial pressure of 10 Pa using polycarbonate plastic substrates 201b and 201c. Subsequently, a solution of heptadecafluorotetrahydrodecyl-1-trimethoxysilane is allowed to act on the plastic substrates 201b and 201c to coat the water repellent film 205. Further, the antireflection film 207 is coated on the back surfaces of the plastic substrates 201b and 201c by sputtering silica. The liquid container 201 is formed using such plastic substrates 201b and 201c.

  Here, the adhesion of the water-repellent film 205 can be improved by performing plasma treatment on the plastic substrates 201b and 201c and coating the water-repellent film 205 after making the surfaces of the plastic substrates 201b and 201c uneven. Note that the unevenness formed on the plastic substrates 201b and 201c by the plasma treatment is of a level that does not cause light scattering, and does not affect the light transmittance.

  Further, the liquid container 201 includes a first electrode 202 that is disposed so as to sandwich the hydrophilic film 206, is in contact with the liquid, an insulating film 204 that is sandwiched between the plastic tube 201a and the water-repellent film 205, and an insulating film. A second electrode 203 insulated from the liquid by 204 is also provided. The first electrode 202 and the second electrode 203 are connected to the focus controller 114a shown in FIG. 3, and a voltage is applied between these electrodes by the focus controller 114a. The first electrode 202 corresponds to an example of the first electrode according to the present invention, and the second electrode 203 corresponds to an example of the second electrode according to the present invention. The focus controller 114a corresponds to an example of a control unit referred to in the present invention.

  In the liquid container 201 as described above, the conductive liquid 301 and the insulating liquid 302 having different optical refractive indexes are stored. In this embodiment, a conductive liquid in which a supporting electrolyte (tetrabutylammonium perchlorate 0.1 mol / L) is added to water is applied, and an organic solvent (Isopar: manufactured by Exxon) is used as the insulating liquid 302. ) Applies. The conductive liquid 301 corresponds to an example of the conductive liquid referred to in the present invention, and the insulating liquid 302 corresponds to an example of the insulating liquid referred to in the present invention.

  In a state where no voltage is applied between the first electrode 202 and the second electrode 203, the conductive liquid 301 repels the water-repellent film 205, whereby the boundary surface between the conductive liquid 301 and the insulating liquid 302. The shape becomes as shown by the solid line. At this time, the first electrode 202 and the conductive liquid 301 come into contact with each other.

  When the focus controller 114a applies a voltage between the first electrode 202 and the second electrode 203 in accordance with an instruction from the signal processing unit 120 shown in FIG. 3, charges are released from the first electrode 202 to the conductive liquid 301. The second electrode 203 collects charges having a polarity opposite to that of the charges released to the conductive liquid 301. The charge released to the conductive liquid 301 and the charge of the second electrode 203 are attracted by Coulomb force, and the charge in the conductive liquid 301 is attracted to the vicinity of the water repellent film 205. As a result, the boundary surface between the conductive liquid 301 and the insulating liquid 302 changes to a shape as indicated by a dotted line in FIG. 4, for example.

  Using this focus lens 114, the TTLAF function is realized by the following procedure.

  First, by changing the voltage applied to the first electrode 202 and the second electrode 203 little by little by the focus controller 114a, the shape of the boundary surface between the conductive liquid 301 and the insulating liquid 302 is changed. An image signal is acquired by the solid-state imaging device 111 shown in FIG. Subsequently, the contrast of the imaging signal is detected by the AF / AE calculation unit 126, and a voltage at which a contrast peak is obtained is applied to the first electrode 202 and the second electrode 203. In this way, the subject can be focused by taking a picture with the lens shape determined.

  In addition, since electric charge is discharged from the first electrode 202 to the conductive liquid 301, a current is passed through the conductive liquid 301 although it is weak. For this reason, the conductive liquid 301 is electrolyzed to generate gas. However, since the liquid container 201 allows gas to pass therethrough, the generated gas escapes from the liquid container 201 before forming bubbles, and for a long time. Light transmittance can be maintained.

  In addition, since the liquid container 201 is made of plastic, it is possible to reduce a problem that the liquid container 201 is damaged during use, and to reduce the weight of the digital camera 100.

  Further, since the antireflection film 207 is provided on the optical path, it is possible to avoid a problem that the light transmittance is reduced due to the reflection of light.

  Here, the example in which the liquid container 201 is provided with the antireflection film 207 has been described above. However, for example, when the liquid container is made of plastic having a high light transmittance, the antireflection film is provided. May be omitted.

  In the above description, an example in which two types of liquids, that is, a conductive liquid and an insulating liquid are stored in the liquid container has been described. However, three or more kinds of liquids are stored in the liquid container according to the present invention. May be.

  In the above description, an example in which the optical element of the present invention is applied to a focus lens has been described. However, the optical element of the present invention may be applied to a zoom lens or the like.

Subsequently, various forms that can be adopted in each component constituting the present invention will be additionally described.
<Liquid container>
The plastic constituting the liquid container according to the present invention may be any one, but as the polymer forming the plastic film, polymethyl methacrylate, cellulose ester (for example, triacetyl cellulose, diacetyl cellulose, typically Are TAC-TD80U and TD80UF manufactured by Fuji Photo Film Co., Ltd., polyamide, polycarbonate, polyester (for example, polyethylene terephthalate, polyethylene naphthalate), polystyrene, polyolefin, norbornene resin (Arton: trade name, manufactured by JSR), non Examples thereof include crystalline polyolefin (Zeonor: trade name, manufactured by Nippon Zeon Co., Ltd.). Among these, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, and amorphous polyolefin (Zeonor: trade name, manufactured by Nippon Zeon Co., Ltd.) are preferable.
<Antireflection film>
As a method of attaching the antireflection film to the liquid container according to the present invention, it is preferable to provide an adhesive layer on one side.

  Further, the reflectance (regular reflectance) of the optical element of the present invention provided with an antireflection film is preferably 2.0% or less, and more preferably 1.5% or less. In the present invention, the antireflection film may contain at least one selected from silicon dioxide, silicon nitride, silicon oxide with adjusted oxygen content, titanium oxide, titanium nitride, and titanic acid nitride compound. preferable. Preferably, the antireflection film is a laminate of layers made of a compound selected from the above compounds, and more preferably made of a compound selected from silicon dioxide, silicon nitride, titanium oxynitride and titanium nitride. It is a laminate of layers. Particularly preferred antireflection films are (a) a titanium oxynitride or titanium nitride layer, (b) a silicon nitride or silicon oxide layer with an adjusted oxygen content, and (c) a silicon dioxide layer on a transparent support. It is the laminated body laminated | stacked in order of.

  The layer thickness of the (a) titanium oxynitride or titanium nitride is preferably 1 μm or more and 50 μm or less, more preferably 3 μm or more and 30 μm or less. When this layer is a titanium oxynitride layer, the nitrogen / titanium atomic ratio is preferably 0.5 or more, and more preferably 0.6 or more. The (b) silicon nitride or silicon oxide layer having an adjusted amount of oxygen preferably has a thickness of 1 μm to 100 μm, more preferably 0.7 to 1.3. The (b) silicon dioxide layer preferably has a thickness of 10 μm or more and 150 μm or less, more preferably 30 μm or more and 130 μm or less.

The lamination can be formed by a sputtering method, a vacuum deposition method, an ion plating method, a plasma CVD method, a plasma PVD method, or a metal or metal oxide ultrafine particle coating method. Sputtering, vacuum deposition, and ion plating are preferable, and sputtering is particularly preferable. As a method for forming a metal oxide film by a sputtering method, reactive sputtering is performed using a metal target mainly composed of nitrogen and titanium, or a target that is a sintered body mainly composed of silicon oxide and titanium oxide. be able to. An inert gas such as argon is used as the sputtering gas in the reactive sputtering method, and oxygen and nitrogen are used as the reactive gas. As the discharge formation, DC magnetron sputtering, RF magnetron sputtering, or the like can be used. Further, as a method for controlling the flow rate of oxygen, it is preferable to carry out by a plasma emission monitor method.
<Liquid>
The conductive liquid and the insulating liquid referred to in the present invention may be two or more kinds of liquids having different refractive indexes and not mixed with each other.

  Any combination of these liquids may be used, but a combination of water and an organic solvent is preferable. As the organic solvent, preferably, hydrocarbons (hexane, heptane, pentane, octane, isopar (exxon), etc.), hydrocarbon aromatic compounds (benzene, toluene, xylene, mesitylene, etc.), halogenated hydrocarbons ( Difluoropropane, dichloroethane, chloroethane, bromoethane, etc.), halogenated hydrocarbon aromatic compounds (such as chlorobenzene), and ether compounds (difluether, anisole, diphenyl ether, etc.) are preferred.

  Moreover, it is preferable to add a supporting electrolyte to water for the purpose of increasing electrical conductivity. As the supporting electrolyte, TMAP: Tetra methyl ammonium perchlorate, TBAF: Tetrabuty ammonium fluoride, or the like is used.

  Here, the basic embodiment for realizing the concept of the present invention has been described above. However, when the optical element employed in the present invention is put into practical use, dust, water droplets, or the like adhere to the optical path. It is preferable to devise measures to prevent a problem that the lens performance deteriorates.

  For example, it is preferable to provide a water-repellent film on the outer surface (hereinafter, this surface is referred to as a light transmission surface) that intersects with the optical path of the container containing the liquid. By imparting water repellency to the light transmitting surface, dust and water droplets can be prevented from adhering and the high light transmittance of the optical element can be maintained. The material constituting the water-repellent film is preferably a silicone resin, an organopolysiloxane block copolymer, a fluorine-based polymer, or polytetrafluoroethane.

  It is also preferable to attach a hydrophilic film to the light transmission surface of the container constituting the optical element. By imparting hydrophilic oil repellency to the light transmitting surface, it is possible to prevent dust from adhering. As this hydrophilic film, a film composed of an acrylate polymer, or a film coated with a surfactant such as a nonionic organosilicone surfactant is preferable. Monomer plasma polymerization, ion beam treatment, and the like can be applied.

  It is also preferable to attach a photocatalyst such as titanium oxide to the light transmission surface of the container constituting the optical element. Dirt is decomposed by the photocatalyst that reacts with light, and the light transmission surface can be kept clean.

  It is also preferable to provide an antistatic film on the light transmission surface of the container constituting the optical element. If static electricity accumulates on the light transmission surface of the container or is charged by an electrode, dust or dust may stick to the light transmission surface. By attaching an antistatic film to the light transmission surface, such unnecessary objects can be prevented from being attached and the light transmission of the optical element can be maintained. The antistatic film is preferably composed of a polymer alloy material, and the polymer alloy system may be a polyether type, a polyether ester amide type, those having a cationic group, Name, Daiichi Kogyo Seiyaku Co., Ltd.). The antistatic film is preferably produced by a mist method.

  Further, an antifouling material may be applied to the container constituting the optical element. As the antifouling material, a fluororesin is preferable, but specifically, a fluorine-containing alkylalkoxysilane compound, a fluorine-containing alkyl group-containing polymer, an oligomer, or the like is preferable, and has a functional group capable of crosslinking with the curable resin. Is particularly preferred. Moreover, it is preferable that the addition amount of antifouling | stain-proof material is a required minimum amount which expresses antifouling property.

It is a schematic block diagram of the liquid lens which is a comparative example. It is the external appearance perspective view which looked at the digital camera with which one Embodiment of this invention was applied from front diagonally upward. It is a schematic block diagram of the digital camera shown in FIG. It is a schematic block diagram of a focus lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid lens 11 Container 11a Tube 11b, 11c Cap 12 1st electrode 13 2nd electrode 14 Insulating film 15 Water-repellent film 16 Hydrophilic film 21 Water 22 Oil 100 Digital camera 101 Shooting lens 102 Optical viewfinder objective window 103 Auxiliary light emission Unit 104 power switch 110 imaging optical system 111 solid-state imaging device 112 shutter 112a shutter motor 113 iris 113a iris motor 114 focus lens 114a focus controller 115 zoom lens 115a zoom motor 120 signal processing unit 120a analog processing (A / D) unit 120b digital signal Processing unit 120c Motor driver 121 System controller 122 Image signal processing unit 123 Image display control unit 124 Image compression unit 125 Media controller Controller 126 AF / AE calculation unit 127 key controller 128 buffer memory 129 internal memory 1200 bus 130 image display unit 140 external recording medium 150 release switch 160 shooting mode switch 170 zoom switch 201 liquid container 201a plastic tube 201b, 201c plastic substrate 202 First electrode 203 Second electrode 204 Insulating film 205 Water-repellent film 206 Hydrophilic film 207 Antireflection film 301 Conductive liquid 302 Insulating liquid

Claims (9)

Consists of an insulating liquid that has different refractive indexes, is immiscible with each other, each has optical transparency, and an electrically conductive liquid that generates a gas when energized and contains a plastic that transmits the gas. A liquid container that transmits light at least in a predetermined optical axis direction;
A first electrode in contact with the conductive liquid in the liquid container;
An optical element comprising: a second electrode insulated from the conductive liquid in the liquid container.   2. The optical element according to claim 1, wherein the liquid container is made of a plastic made of a bicyclic aliphatic monomer.   2. The liquid container according to claim 1, wherein at least a part of the inner surface is covered with a coating film having lower wettability with respect to the conductive liquid than wettability with respect to the insulating liquid. Optical elements. The conductive liquid is an aqueous solution, and the insulating liquid is oil.
2. The optical element according to claim 1, wherein at least a part of the inner surface of the liquid container is covered with a coating film formed by water repellent treatment with a fluorine-based silane coupling agent. .   The optical element according to claim 1, further comprising an antireflection film for preventing light reflection on an outer surface of the liquid container intersecting with the optical axis direction.   6. The optical element according to claim 5, wherein the antireflection film is made of a fluorine-based polymer.   6. The optical element according to claim 5, wherein the antireflection film is formed by laminating silica and a polymer on the outer surface. Consists of an insulating liquid that has different refractive indexes, is immiscible with each other, each has optical transparency, and an electrically conductive liquid that generates a gas when energized and contains a plastic that transmits the gas. A liquid container that transmits light at least in a predetermined optical axis direction;
A first electrode in contact with the conductive liquid in the liquid container;
A second electrode insulated against the conductive liquid in the liquid container,
The lens unit, wherein a shape of a boundary surface between the insulating liquid and the conductive liquid changes according to a voltage applied between the first electrode and the second electrode. Consists of an insulating liquid that has different refractive indexes, is immiscible with each other, each has optical transparency, and an electrically conductive liquid that generates a gas when energized and contains a plastic that transmits the gas. A liquid container that transmits light at least in a predetermined optical axis direction;
A first electrode in contact with the conductive liquid in the liquid container;
A second electrode insulated from the conductive liquid in the liquid container;
A control unit that changes a shape of a boundary surface between the insulating liquid and the conductive liquid by applying a voltage between the first electrode and the second electrode;
An imaging apparatus comprising: an imaging element that forms an image signal representing the subject light by imaging the insulating liquid and subject light that has passed through the conductive liquid on a surface thereof.

Images