JP5506761B2 - Liquid-based optical and electronic devices - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical device in which unintended deformation of an interface is avoided.SOLUTION: The present invention discloses an optical device comprising a container enclosing an insulating liquid (A) and a liquid (B) responsive to an electric field. The insulating liquid (A) and the liquid (B) responsive to an electric field are immiscible and are in contact with each other via an interface (14), and at least one of the liquids (A) and (B) are at least partially placed in a light path through the container. The optical device further comprises: electrode arrangements (2 and 12) for controlling a shape of the interface (14) by means of a voltage; and means (100) for preventing the interface (14) from an exposure to an external electric field. Consequently, the build-up of an electrostatic charge on a surface of the optical device is avoided, which prevents an unwanted distortion of the interface (14) caused by the interaction of the liquid (B) responsive to an electric field and the electrostatic charge.

Description

  The present invention is a container containing an immiscible insulating liquid and an electric field-responsive liquid that are in contact with each other via an interface, the liquid being at least partially disposed on an optical path through the container And an optical device including a container and an electrode configuration that controls the shape of the interface by voltage.

  The invention further relates to an electronic device comprising such an optical device.

  Optical devices based on the manipulation of liquids are rapidly gaining great commercial interest. This is due, inter alia, to the need for mechanical moving parts and the relative simplicity of the device, which makes the device cheaper and more durable.

  For example, Patent Document 1 discloses an optical device in which two immiscible liquids having the same refractive index but different transmittances are incorporated, and one of the two liquids is conductive. Varying the interface between these two liquids changes the amount of each liquid in the optical path through the device, resulting in a diaphragm.

Patent Document 2 discloses a cylindrical variable focus lens that incorporates two immiscible fluids, two fluids having different refractive indices, one conductive and the other insulating. The shape of the interface of the two fluids is manipulated by applying a voltage across the lens, which can be used to effect a change in the focal point of the lens. One of the cylindrical wall and the transparent lid of the cylindrical body is coated with a hydrophobic coating, thereby realizing an interface with a large curvature that contributes to a large optical power region for the lens, at least in the off state. It is ensured that the contact area between the wall and the conductive fluid, typically a polar liquid, is minimized.
US Patent Application Publication No. 2001/0017985 International patent application WO 03/069380

  A problem that arises with such devices is that unintentional deformation of the interface can occur after a certain period of time, thereby hindering the desired optical behavior of the interface.

An object of the present invention is to provide an optical device that prevents unintended deformation of an interface.
The present invention further aims to provide an electronic device comprising such an improved optical device.

According to one aspect of the present invention, a container containing an immiscible insulating liquid that is in contact with each other via an interface and a liquid that reacts with an electric field, wherein at least one of the two liquids is the container A container disposed at least partially on an optical path through
Means for controlling the shape of the interface;
Means for preventing the interface from being exposed to an external electric field.

  In the context of the present invention, the term 'electric field-responsive liquid' is intended to include conductive liquids, polar fluids and polarizable fluids.

  The present invention is based on the finding that unintended interface deformation is caused by exposing the interface to an external electric field, which can be a static field caused by the accumulation of electrostatic charges on the surface of the container. Static charge build-up can be caused, for example, by intended or unintended friction on the surface of the container.

  The means for controlling the shape of the interface may include an electrode configuration for controlling the shape of the interface by voltage. This is particularly effective when the optical device is a variable focus lens, since this facilitates a lens with a large optical power.

  In one embodiment, the surface is part of the transparent end of the container and means for preventing the interface from being exposed to an external electric field is a conductive layer that forms part of the transparent end. including. This has the effect of preventing the accumulation of static charge on the transparent end.

  Effectively, the electrode configuration includes an electrode that contacts a liquid that is responsive to an electric field, and a conductive layer is conductively coupled to the electrode. In this example, the conductive layer is maintained at the same potential as the liquid that reacts to the electric field, thereby ensuring that the presence of any static charge on the transparent edge does not affect the shape of the interface. Is done.

  In a further embodiment, the means for preventing the interface from being exposed to an external electric field includes a Faraday cage surrounding the container. This embodiment may be combined with the previous embodiment, but protects the optical device from exposure to an external electric field and, as a result, prevents the accumulation of electrostatic charges on the surface of the container of the optical device.

  The Faraday cage may include a conductive coating that at least partially covers a further container. This has the effect that the Faraday cage can be manufactured separately from the optical device.

  The further container may be at least partially transparent. This has the effect that the further container can completely enclose the container of the optical device inside without compromising the optical path through the optical device.

According to a further aspect of the present invention, an electronic device including an optical device comprising:
A container containing an immiscible insulating liquid that contacts each other through an interface and a liquid that reacts to an electric field, wherein one of the two liquids is at least partially on an optical path through the container Arranged in a container,
Means for controlling the shape of the interface;
Means for preventing the interface from being exposed to an external electric field;
A drive circuit connected to the means for controlling the shape of the interface;
An electronic device is provided that includes a power supply for supplying power to the drive circuit, and means for preventing the interface from being exposed to an external electric field is coupled to a terminal of the power supply.

  The electronic device of the present invention has an effect that the performance of the optical device is not hindered by an external electric field, such as accumulation of electrostatic charges on the surface of the container of the optical device.

  In one embodiment, the means for preventing the interface from being exposed to an external electric field is coupled to the terminal of the power source, preferably ground, and the means is kept at the same potential as the liquid that reacts to the electric field. Is guaranteed.

  In an alternative embodiment, the means for preventing the interface from being exposed to an external electric field forms part of a device that shields the electronic circuitry of the electronic device from external radiation. This has the effect that the optical device is protected from static charge accumulation by extending the configuration already present in the electronic device and is cost effective.

It is a figure which shows schematically the variable focus lens of a prior art. 1 schematically shows an optical device according to the invention. FIG. 6 is a diagram schematically showing another optical device according to the present invention. 1 schematically shows an electronic device according to the invention. FIG. 6 schematically shows another electronic device according to the invention.

  The present invention will now be described in detail by way of non-limiting examples with reference to the accompanying drawings.

  The drawings are only schematic and are not to scale. It should also be understood that the same reference numerals are used throughout the figures to indicate the same or similar parts.

FIG. 1 shows a variable focus lens disclosed in Patent Document 2 described above. The variable focus lens includes a first fluid A and a second fluid B housed in a cylindrical chamber. These fluids are immiscible, have different refractive indices, and preferably have the same density to prevent shape-dependent gravitational effects on the shape (orientation) of the fluid including the interface 14 between the fluids. Have. The cylindrical chamber further includes a first end 4 and a second end 6 that may be coupled to a parylene stack as well as the inner wall of the cylindrical chamber. The conductive fluid B is confined by the insulating fluid A in the absence of an applied voltage, coated with a hydrophobic coating material such as AF1600 ^™ from DuPont. The shape of the interface 14 is between the cylindrical electrode 2 embedded in the chamber wall and the tubular electrode 12 on the second lid 6 which is preferably transparent and in conductive contact with the second fluid B. By changing the direct current voltage or alternating current voltage from V1 to V2, the convex shape shown by shape (a) can be switched to the concave shape shown by shape (b) in a continuous manner. As a result, the focal point of the optical path L passing through the cylindrical body is changed.

  The transparent end 4 may be a glass or polymer lid or other suitable transparent material and may be in the form of a lens. For example, accidental rubbing of the transparent end 4 or exposure of the fluid A or B container to an external electric field, such as by cleaning the end 4 with a cloth or placing an optical device in a pocket of clothing, the transparent end 4 The accumulation of electrostatic charges on the surface of the container, such as section 4, is generated. This charge can attract the conductive fluid B, thereby disturbing the shape of the interface 14 between the fluids A, B, as shown in (c), thereby causing the desired optical properties of the lens. A deviation in behavior occurs. Clearly this is a highly undesirable effect since it takes several hours or more to remove the static charge. It should be pointed out that a similar undesirable effect occurs when the lens is exposed to an external electric field.

  It should be emphasized that this undesired effect has been described by way of example using prior art lenses from U.S. Pat. No. 6,053,836, but other such as the diaphragm disclosed in U.S. Pat. Liquid-based optical devices suffer from this problem as well.

In FIG. 2 and the subsequent drawings, the variable focus lens of FIG. 1 is shown as an embodiment of the optical apparatus of the present invention. However, it should be emphasized that the teachings of the present invention can be applied to other liquid-based optical devices. In FIG. 2, the variable focus lens of FIG. 1 is extended by a conductive layer 100 to prevent exposure of the interface to the external electric field of the lens, ie the electric field on the first end 4. The conductive layer 100 is shown on the inner surface of the end 4, but an arrangement on the outer surface of the end 4 is also conceivable. The conductive layer 100 can be realized by any known transparent conductive material, such as indium tin oxide (ITO), indium oxide (In ₂ O ₃ ), or tin oxide (SnO ₂ ). Preferably, the conductive layer 100 is maintained at the same potential as the liquid B that reacts to the electric field, which causes the conductive layer 100 to be applied to the electrode 12 that contacts the liquid B that reacts to the electric field, as shown in FIG. This can be realized by conductive coupling.

  FIG. 3 shows another embodiment of the optical device of the present invention. The variable focus lens of FIG. 1 is placed in a further container 120. The further container 120 may open on the opposite side of the variable focus lens ends 4, 6 or may have a transparent portion on the opposite side of these ends. The further container 120 may further include a metallic body, or may include a non-conductive material that can be transparent, such as plastic or glass. If the further container 120 includes such a non-conductive material, the further container 120 further includes a conductive coating 140 that can be transparent, which is provided on the inner or outer surface of the further container 120. It's okay.

  As a result, the further container 120 acts as a Faraday cage around the variable focus lens, thereby preventing the accumulation of electrostatic charges on the surface of the container. Furthermore, while the external electric field also interferes with the intended optical behavior of the optical device, the Faraday cage also protects the optical device against such interference. The conductive coating 140 may be applied to the outer surface of the variable focus lens container, in which case the further container 120 may be omitted. Preferably, the conductive coating 140 or the conductive further container 120 is conductively coupled to the electric field responsive liquid B, ensuring that the Faraday cage is maintained at the same potential as the electric field responsive liquid B. To do. This conductive coupling may be realized via the electrode 12. It should be emphasized that the above-described embodiment of the Faraday cage can be combined with any of the embodiments of the conductive layer 100 as shown in FIG. 2 without departing from the scope of the present invention.

  In this regard, it should be emphasized that in this application, the means for controlling the shape of the interface 14 is shown as an electrode configuration that controls the shape of the interface 14 by voltage, but the priority date is May 14, 2003. Other means for controlling the shape of the interface 14 are equally applicable, such as the means for controlling the shape of the interface 14 disclosed in the unpublished European patent application 03101335.2.

  In this application it is disclosed that the variable focus lens includes two immiscible liquids with different reflectivities. The lens has two chambers that are distributed to the two liquids: a first chamber in which the interface is located and the optical path passes, and a second chamber that has two connections in the first chamber. . The second chamber includes a pump that is used to change the volume of the respective liquid in both chambers. As a result, the focal point of the lens is changed by translating the position of the interface between the two liquids relative to the inner wall of the first chamber, in addition to changing the shape of the interface, ie the curvature of the interface.

  FIG. 4 shows one embodiment of the electronic device 1 of the present invention including an optical device having a conductive layer 100 on the end 4 as shown in FIG. 2 and its detailed description. The electronic device 1 further includes a drive circuit 20 that applies a voltage across the electrode configuration including the electrodes 2 and 12 and an image sensor 30 that captures an image entering the electronic device 1 via the optical path of the optical device. The drive circuit 20 and the image sensor 30 are supplied with power by a power supply 40, and one terminal, for example, the ground side of the power supply 40 is coupled to the conductive layer 100. This may be the ground of the electronic device 1. Alternatively, the conductive layer 100 may be coupled to the power supply 40 via the electrode 12 in a configuration similar to that shown in FIG.

  FIG. 5 shows another embodiment of the electronic device 1 of the present invention, including a liquid-based optical device, such as a variable focus lens, a drive circuit 20, an image sensor 30, and a power source (not shown). The electronic device 1 further includes an electronic circuit 50, which is shielded by a shielding material 60 from external radiation, i.e. radiation from outside the electronic circuit. The shielding material 60 may be any suitable material known to those skilled in the art, such as a conductive foil or a metal housing. The shielding material 60 extends onto the container of the optical device without blocking the light path through the optical device and prevents the accumulation of electrostatic charges on the surface of the container of the optical device.

  It should be noted that the above-described embodiments are illustrative and not limiting of the present invention, and those skilled in the art will be able to design a number of alternative embodiments without departing from the scope of the appended claims. Will be able to. In the original claims, reference signs in parentheses should not be construed as limiting the claims. The word “comprising” does not exclude the presence of elements or steps other than those listed in a claim. The singular expression attached to an element does not exclude the presence of a plurality of such elements. The present invention can be implemented by hardware including several distinct elements. In the device claim enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used effectively.

Claims (7)

A container containing an immiscible insulating liquid that contacts each other through an interface and a liquid that reacts to an electric field, wherein one of the two liquids is at least partially on an optical path through the container Arranged in a container,
An electrode configuration for controlling the shape of the interface by voltage;
And an Faraday cage surrounding the container and preventing the interface from being exposed to an external electric field. The optical device according to claim 1, wherein the Faraday cage is a further container at least partially covered by a conductive coating .   The optical device according to claim 2, wherein the further container is at least partially transparent. An electronic device comprising the optical device according to any one of claims 1 to 3,
A drive circuit connected to the electrode configuration;
An electronic device including a power supply for supplying power to the drive circuit.   The electronic device of claim 4, wherein the Faraday cage is coupled to a terminal of the power source.   The electronic device according to claim 5, wherein the terminal is a ground.   6. An electronic device according to claim 4 or 5, wherein the Faraday cage forms part of a device that shields the electronic circuit of the electronic device from external radiation.

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