JP4471220B2 - Fluid prism - Google Patents

Description

  The present invention relates to a fluid prism in which a fluid is filled inside to deflect incident light in a predetermined angle and direction.

  In recent years, higher performance such as downsizing and weight reduction of an imaging device such as a camera and higher magnification of an optical zoom has been promoted. There is a demand for higher performance in imaging devices. As one of the high performance, there is a method of mounting a pan / tilt mechanism that widens the imaging range.

  As the pan / tilt mechanism, for example, there is a tilt mechanism that widens an imaging range (angle) by arranging a prism in front of a lens to deflect incident light. The use of a variable prism as the prism has been studied. The variable prism is a prism whose apex angle can be changed to an arbitrary angle. For example, there is a liquid prism disclosed in Patent Document 1.

  Patent Document 1 discloses a variable apex prism in which the outer periphery between two transparent plates facing each other is sealed with a flexible film and the sealed space is filled with a transparent liquid. In this variable apex angle prism, two transparent plates are driven by a prism driving unit made of a motor to obtain an arbitrary apex angle and deflect the light beam.

However, the variable apex angle prism of Patent Document 1 has a problem that the response and accuracy of the variable prism are low because two transparent plates are driven by a motor. Further, since the physique of the motor for driving the two transparent plates is large, there is a problem that the physique of the variable prism itself becomes large and the physique of the entire imaging apparatus having the variable prism becomes large.
Japanese Patent Laid-Open No. 7-20390

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a variable prism that is small in size and capable of controlling the apex angle with high accuracy.

  In order to solve the above-mentioned problems, the present inventors have studied the variable prism, and as a result, have reached the present invention.

That is, the fluid prism of the present invention includes an insulating member having a bottom plate that is electrically insulating and capable of transmitting light, and a fluid that is disposed on the surface of the bottom plate of the insulating member and that can transmit light. An electrode member disposed on the surface opposite to the fluid of the insulating member, a power supply means for applying a voltage to the fluid and the electrode member, and a swingable state on the surface of the fluid in accordance with the flow of the fluid And a transparent plate capable of transmitting light .

  The fluid prism of the present invention inclines the refractive surface made of the fluid surface to a desired angle by the action of electrowetting. In other words, since the fluid prism of the present invention deflects the fluid prism by applying a voltage to the fluid and the electrode member, the refracting surface can be controlled with high responsiveness and high accuracy compared to driving by a conventional motor. It can be performed. Further, since the motor is not required unlike the conventional liquid prism, the physique of the entire fluid prism can be reduced.

The fluid prism of the present invention includes an insulating member having a bottom plate that is electrically insulating and capable of transmitting light, and an electrically conductive fluid that is disposed on the surface of the bottom plate of the insulating member and that can transmit light. An electrode member disposed on a surface opposite to the fluid of the member, a power supply means for applying a voltage to the fluid and the electrode member, and disposed on the surface of the fluid so as to be able to swing according to the flow of the fluid. And a transparent plate capable of transmitting light .

  In the fluid prism of the present invention, light is transmitted through a fluid and a bottom plate that can transmit light. In the fluid prism of the present invention, when the power supply means applies a voltage to the fluid and the electrode member, the surface tension of the fluid in the vicinity of the electrode member to which the voltage is applied changes due to a so-called electrowetting phenomenon, and apparently "Wettability" changes. Then, the fluid on the bottom plate flows due to the change in the “wetting property”, and the thickness of the fluid partially changes. As a result, the surface opposite to the bottom plate surface of the fluid is inclined with respect to the bottom plate surface, and the refractive surface. It becomes. Thereby, the fluid forms a prism.

  In addition, since the fluid prism of the present invention deflects the fluid prism by applying a voltage to the fluid and the electrode member, the refractive surface can be controlled with higher accuracy than driving by a conventional motor. Further, since the motor is not required unlike the conventional liquid prism, the physique of the entire fluid prism can be reduced.

  The electrode member is preferably disposed on the back surface of the bottom plate. By disposing the electrode member on the back surface of the bottom plate, the number of members for forming the prism by the fluid does not increase, and the fluid prism can be configured easily. The electrode member is preferably disposed at a position corresponding to the peripheral edge of the fluid.

  It is preferable that a plurality of electrode members are arranged. By arranging a plurality of electrode members, the number of portions where the surface tension of the fluid changes increases, and the fluid can be controlled more. The number of electrode members is not particularly limited, but is preferably as the number of electrode members is increased, and more preferably four or more.

  The plurality of electrode members are preferably arranged at the periphery of the fluid, and are preferably arranged at uniform intervals in the circumferential direction on the outer periphery of the fluid.

On the surface of the fluid, a transparent plate capable of transmitting light and disposed so as to be able to swing according to the flow of the fluid is disposed. By disposing a transparent plate on the surface of the fluid, the surface (refractive surface) of the fluid on which light is easily incident becomes a flat surface without requiring complicated control. As a result, the fluid prism can uniformly deflect the incident light.
The transparent plate is preferably supported by a rotatable support shaft.

  In the fluid prism of the present invention, the fluid may be a substance having a refractive index different from the atmosphere on the surface side of the fluid (or the transparent plate), and is preferably a liquid. Specifically, water, silicone oil, matching oil, etc. can be mentioned.

  It is preferable that the insulating member has a cylindrical portion standing on the surface of the bottom plate, the fluid is disposed inside the insulating member, and the electrode member is disposed on the outer peripheral surface of the cylindrical portion. That is, it is preferable that the insulating member forms a chamber with the bottom plate and the cylindrical portion, and the fluid is disposed inside the chamber. With such a configuration, fluid can be easily held. And by arrange | positioning an electrode member to the outer peripheral surface of a cylindrical part, the flow of the fluid hold | maintained inside the chamber can be controlled more easily. Furthermore, by disposing the electrode member on the outer peripheral surface of the cylindrical portion, the insulating member does not exist in the light path, the electrode member does not shield the light transmitted through the fluid prism, and the entire surface of the bottom plate of the insulating member. Light can be transmitted.

  It is preferable that a plurality of electrode members are arranged. By arranging a plurality of electrode members, the number of portions where the surface tension of the fluid changes increases, and the fluid can be controlled more. The number of electrode members is not particularly limited, but is preferably as the number of electrode members is increased, and more preferably four or more. The plurality of electrode members are preferably arranged along the circumferential direction on the outer peripheral surface of the cylindrical portion, and more preferably arranged at uniform intervals in the circumferential direction. Further, when the plurality of electrode members are arranged along the circumferential direction of the cylindrical portion, the positions in the axial direction may be the same or different. Further, when the plurality of electrode members are arranged along the circumferential direction of the cylindrical portion, the electrode members arranged side by side in the circumferential direction may be formed by a plurality of electrode members arranged in the axial direction.

The transparent plate is preferably arranged in a state of floating inside the insulating member. By disposing the transparent plate, the surface of the fluid on which light is easily incident becomes a flat surface without requiring complicated control. As a result, the fluid prism can uniformly deflect the incident light.

  It is preferable that a second fluid having a refractive index different from that of the fluid is disposed above the fluid. When the second fluid is disposed on the upper part of the fluid, the robustness (tilt angle stability) against disturbances such as vibration is improved. When two fluids are held in the chamber, the interface between the two fluids becomes a refractive surface. Further, when a transparent plate is disposed at the interface between the two fluids, this transparent plate becomes a refractive surface.

  In the fluid prism of the present invention, the fluid may be a substance having a refractive index different from the atmosphere on the surface side of the fluid (or the transparent plate), and may be a gas or a liquid. The fluid is preferably a liquid. Specifically, examples of the liquid that can be used as the fluid include water, silicone oil, and matching oil.

  Since the fluid prism of the present invention can deflect incident light, it is preferably applied to an imaging device. In particular, a pan / tilt mechanism can be formed by combining with a zoom mechanism of an imaging apparatus. In addition, since the control can be performed with high accuracy, the fluid prism of the present invention can be applied to camera shake correction of an imaging apparatus.

  Hereinafter, the present invention will be described using examples.

  As an example of the present invention, a fluid prism was manufactured.

Example 1
The fluid prism according to this embodiment includes an insulating member 1, a liquid 2, an electrode plate 3, a transparent plate 4, and a power source 5. The configuration of the fluid prism of this embodiment is shown in FIGS. 1 and 2 are side views, and FIG. 3 is a bottom view.

  The insulating member 1 is a plate-like member made of a material that can transmit light and has electrical insulation properties. The insulating member 1 has a light transmitting portion 10 through which light passes at the center thereof.

  The liquid 2 is water disposed on the surface 10 a of the light transmitting part 10 of the insulating member 1. The liquid 2 is floating on the surface 10a of the insulating member 1 due to surface tension.

  The electrode plate 3 is disposed on the back surface 10 b of the light transmitting portion 10 of the insulating member 1 in a state of being in contact with the insulating member 1. The electrode plate 3 has four substantially fan-shaped electrode portions 30, 30, 30, 30, and four electrode portions 30 are arranged at equal intervals in the circumferential direction on the peripheral portion of the light passing portion 10. Has been.

  The transparent plate 4 includes a substantially circular transparent portion 40 that can transmit light, and a support portion 41 that supports the transparent portion in a swingable state. The transparent plate 40 is supported by the support ring 42 so as to be swingable by the inner support shafts 43 and 43. The support ring 42 is supported by the support portion 41 in a state in which it can swing by the outer support shafts 44, 44. The inner support shafts 43 and 43 and the outer support shafts 44 and 44 are orthogonal to each other. That is, the transparent portion 40 can rotate in all directions by swinging around the inner support shafts 43 and 43 and the outer support shafts 44 and 44 as the rotation center. The transparent plate 4 is specifically shown in FIG.

  The transparent plate 4 is disposed in a state where the back surface 40 b of the transparent portion 40 is in contact with the upper surface of the liquid 2. The transparent portion 40 can swing along the flow of the liquid 2. In other words, the liquid 2 is in contact only with the front surface 10 a of the light transmitting portion 10 of the insulating member 1 and the back surface 40 b of the transparent portion 40 of the transparent plate 4.

  The power source 5 generates a voltage applied between the four electrode portions 30 of the electrode plate 3 and the liquid 2. Here, the power supply 5 can apply different voltages to the four electrode portions 30.

  The operation of the fluid prism according to the present embodiment will be described with reference to FIGS.

  First, in a state where the power source 5 is not applying a voltage, as shown in FIG. 1, the liquid 2 is floating due to surface tension. At this time, the transparent portion 40 of the transparent plate 4 in contact with the upper surface of the liquid 2 is in a state parallel to the insulating member 1.

Then, the power source 5 is driven to apply a voltage between the electrode portion 30 c and the fluid 2. When a voltage is applied, a so-called electrowetting phenomenon occurs, and the surface tension of the liquid 2 at a position corresponding to the electrode portion 30c of the insulating member 1 changes. Due to this change in surface tension, the contact angle between the liquid 2 and the insulating member 1 changes (decreases) from θ ₀ to θ ₁ . When the contact angle of the liquid 2 with the transparent plate 1 changes, the force that the transparent portion 40 of the transparent plate 4 receives from the liquid 2 changes. In FIG. 2, the downward force applied to the end portion 40c of the transparent portion 40 that is located above the electrode portion 30c increases, and the end portion of the transparent portion 40 that is located above the electrode portion 30d. The downward force applied to the portion 40d to be reduced is relatively reduced. As a result, a rotational moment acts on the transparent portion 40, and the transparent portion 40 rotates around the two support shafts 43 and 44. Then, the transparent portion 40 is inclined with respect to the insulating member 1. As a result, the fluid prism of this example is a prism that allows the transparent portion 40 of the transparent plate 4 to be a refracting surface and allows light to pass through the liquid 2 and the light transmitting portion 10.

  As described above, in the fluid prism of this embodiment, the inclination angle of the transparent portion 40 can be set to a desired angle by applying a voltage from the power source 5 to the four electrode portions 30 and the liquid 2. The fluid prism according to the present embodiment is a highly accurate and responsive prism by controlling the apex angle of the prism by the voltage applied from the power supply 5. Furthermore, since the fluid prism of the present embodiment does not use a motor to drive the transparent portion 40, the physique is downsized.

  Further, in the fluid prism of this embodiment, when a device for detecting the rotation angle of the support shaft such as a strain gauge is assembled to each of the inner support shaft 43 and the outer support shaft 44 of the transparent plate 4, the measurement result is fed back. Thus, the inclination of the transparent portion 40 can be calculated.

(Example 2)
The fluid prism according to this embodiment includes an insulating member 1, a liquid 2, an electrode plate 3, a transparent plate 4, and a power source 5. The configuration of the fluid prism of this embodiment is shown in FIGS.

  The insulating member 1 has a disc-shaped light transmitting portion 10 formed of a material that can transmit light and has an electrical insulating property, and a cylindrical shape that matches the outer peripheral shape of the light transmitting portion 10. This is a bottomed cylindrical member comprising a cylindrical portion 11 made of an electrically insulating material and formed integrally with the portion 10.

  The liquid 2 is water disposed inside the insulating member 1. The liquid 2 is in contact with the surface 10 a of the light transmitting part 10 of the insulating member 1 and the inner peripheral surface 11 a of the cylindrical part 11.

  The electrode plate 3 is disposed on the outer peripheral surface 11 b of the cylindrical portion 11 of the insulating member 1 in a state of being in contact with the insulating member 1. The electrode plate 3 has four electrode portions 30, 30, 30, 30, and the electrode portions 30 are arranged at equal intervals in the circumferential direction of the cylindrical portion 11.

  The transparent plate 4 has a substantially circular shape capable of transmitting light. The transparent plate 4 is disposed inside the insulating member 1 with the back surface 4 b in contact with the upper surface of the liquid 2. The transparent plate 4 can swing along the flow of the liquid 2. That is, the transparent plate 4 is arranged in a state of floating in the liquid 2 inside the insulating member 1. The transparent plate 4 of the present embodiment is configured only by the transparent portion of the transparent plate of the first embodiment.

  The power source 5 generates a voltage applied between the four electrode portions 30 of the electrode plate 3 and the liquid 2. Here, the power supply 5 can apply different voltages to the four electrode portions 30.

  The operation of the fluid prism of the present embodiment will be described with reference to FIGS.

  First, in a state where the power source 5 is not applying a voltage, the transparent plate 4 is floating in the liquid 2 as shown in FIG. At this time, the transparent plate 4 is in a state of spreading in the horizontal direction, and is in a state of being parallel to the light transmitting portion 10 of the insulating member 1.

Then, the power source 5 is driven to apply a voltage between the electrode portion 30 c and the fluid 2. When a voltage is applied, a so-called electrowetting phenomenon occurs, and the surface tension of the liquid 2 at a position corresponding to the electrode portion 30c of the cylindrical portion 11 changes. Due to this change in surface tension, the contact angle between the liquid 2 and the cylindrical portion 11 of the insulating member 1 changes (decreases) from θ ₀ to θ ₁ . When the contact angle of the liquid 2 with the cylindrical portion 11 changes, the force that the transparent plate 4 floating on the liquid 2 receives from the liquid 2 changes. In FIG. 5, the downward force applied to the portion 4c that is the end of the transparent plate 4 and close to the electrode portion 30c increases, and the portion 4d that is the end of the transparent plate 4 and close to the electrode portion 30d is applied. The downward force applied is relatively reduced. Thereby, a rotational moment acts on the transparent plate 4 and the transparent plate 4 rotates. And the transparent plate 4 will be in the state inclined with respect to the light transmission part 10. FIG. As a result, the fluid prism of this example is a prism that allows the transparent plate 4 to be a refracting surface and allows light to pass through the liquid 2 and the light transmitting portion 10.

  As described above, in the fluid prism of this embodiment, the inclination angle of the transparent plate 4 can be set to a desired angle by applying a voltage from the power source 5 to the four electrode portions 30 and the liquid 2. The fluid prism according to the present embodiment is a highly accurate and responsive prism by controlling the apex angle of the prism by the voltage applied from the power supply 5. Furthermore, since the fluid prism of the present embodiment does not use a motor to drive the transparent plate 4, the physique is downsized.

(Example 3)
The present embodiment has the same configuration as the fluid prism of the second embodiment except that a second liquid is further disposed above the transparent plate 4 of the fluid prism of the second embodiment.

  In the fluid prism of the present embodiment, the insulating member 1, the liquid 2, the electrode plate 3, the transparent plate 4, and the power source 5 have the same configuration as that of the second embodiment.

  The second liquid is a liquid having a refractive index different from that of the liquid 2. Furthermore, the two liquids do not dissolve each other. In the present embodiment, the second liquid is made of matching oil having a large refractive index. The second liquid preferably has electrical insulation.

  The fluid prism of this embodiment is driven in the same manner as in the second embodiment. In addition, the same effect as the fluid prism of the second embodiment is exhibited.

  The fluid prism of the present embodiment has a configuration in which a transparent plate 4 is disposed at the interface between two liquids. Thereby, the shaking of the transparent plate 4 is suppressed. That is, the robustness (tilt angle stability) against disturbances such as vibration is improved.

(Deformation)
As a modification of the fluid prism of the third embodiment, a thin film may be disposed at the interface between two liquids. Further, when the thin film is disposed, it is preferable that the thin film and the transparent plate are integrally formed.

(Application to pan / tilt mechanism)
Furthermore, the fluid prism of each of the above embodiments can be applied to a pan / tilt mechanism. A specific description will be given using an example in which the fluid prism of the second embodiment is applied to a pan / tilt mechanism. As shown in FIG. 7, the pan / tilt mechanism of the present embodiment includes a multifocal lens P1, a first mirror P2, a second mirror P3, an image sensor P4, and second mirror moving means (not shown). And a fluid prism P7.

  The multifocal lens P1 includes two lens regions P15 and P16 having different focal lengths, and the lens region P15 has a shorter focal length than the lens region P16.

  The first mirror P2 and the second mirror P3 are ordinary opaque mirrors. The second mirror P3 is parallel to the optical axis of the multifocal lens P1 and does not block the light bundle that has passed through the lens region P15 (FIG. 7A), and is perpendicular to the optical axis of the multifocal lens P1. Thus, the position can be switched between the position (FIG. 7B) inserted so as to shield the light beam that has passed through the lens region P15. The second mirror moving means is means for switching the second mirror P2 between them. As a method for switching between them, the second mirror P3 is formed of a ferromagnetic material or a ferroelectric material, and a method for changing the direction of applying a magnetic field or an electric field, an electrostatic force or a Lorentz force is used. Means can be exemplified.

  The image sensor P4 is disposed at a position corresponding to the image plane, and specifically, is located at the center of the first mirror P2.

  The fluid prism P7 is a fluid prism according to the second embodiment, and includes an insulating member P71, a liquid P72, an electrode plate P73, a transparent plate P74, and a power source (not shown).

  The pan / tilt mechanism can be realized as follows. When the transparent plate P74 is parallel to the incident light side (upper drawing) surface of the multifocal lens P1, the incident light is directly incident on the multifocal lens P1 without bending.

  And if a power supply is driven and a voltage is applied to the electrode part P730c and the liquid P72, the transparent plate P74 will rock | fluctuate. When the transparent plate P74 swings, the transparent plate P74 becomes a refracting surface and incident light is refracted. Since the refractive index of the transparent plate P74 and the liquid P2 is larger than the refractive index of the space P76 (atmosphere, etc.), as shown in FIG. 3B, the incident light is in a direction opposite to the direction in which the transparent plate P74 is swung. Refract. The degree of refraction of incident light can be controlled by controlling the degree of swing of the transparent plate P74. That is, the angle of view can be changed in a desired direction by swinging the transparent plate P74 in the opposite direction to the direction of changing the angle of view of the pan / tilt mechanism.

  A method for switching the focal length will be described below.

  When the focal length is made longer, the second mirror P3 is inserted by the second mirror moving means (FIG. 7B) in order to use the light bundle transmitted through the lens region P16 of the multifocal lens P1. Moving. As a result, the light beam transmitted through the lens region P15 is shielded by the second mirror P3, so that only the light beam transmitted through the lens region P16 is reflected by the first mirror P2 and the second mirror P3 and is on the image plane. The image is formed on the image sensor P4.

  On the contrary, when the focal length is shortened, the second mirror moving means moves to the state where the second mirror P3 is removed (FIG. 7A) in order to use the light bundle transmitted through the lens region P15. As a result, the light beam transmitted through the lens region P15 is not shielded by the second mirror P3 and is stored on the image pickup device P4 on the imaging surface as it is, whereas only the light beam transmitted through the lens region P11. Since there is no second mirror P3, after reflecting the first mirror P2 from the lens region P16, it passes through the lens region P15 as it is toward the object side of the multifocal lens P1.

  Therefore, the light beam that has passed through the lens region P15 is moved as it is, and the light beam that has passed through the lens region P16 advances between the first mirror P2 and the second mirror P3 by a distance (one reciprocal half) considering the difference in focal length. Thus, the image planes from the lens regions P15 and P16 match.

FIG. 3 is a diagram illustrating a configuration of a fluid prism according to the first embodiment. FIG. 3 is a diagram illustrating a configuration of a fluid prism according to the first embodiment. FIG. 3 is a bottom view of the fluid prism according to the first embodiment. FIG. 3 is a diagram illustrating a configuration of a transparent plate of the fluid prism according to the first embodiment. FIG. 6 is a diagram illustrating a configuration of a fluid prism according to a second embodiment. FIG. 6 is a diagram illustrating a configuration of a fluid prism according to a second embodiment. FIG. 6 is a diagram illustrating a configuration of a pan / tilt mechanism including a fluid prism according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insulating member 10 ... Light transmission part 11 ... Cylindrical part 2 ... Liquid 3 ... Electrode board 30 ... Electrode part 4 ... Transparent board 40 ... Transparent part 41 ... Support part 42 ... Support ring 43 ... Inner support shaft 44 ... Outer support Axis 5 ... Power supply P1 ... Multifocal lens P10, P11, P12, P13, P14, P15, P16 ... Lens region P2 ... First mirror P3 ... Second mirror P4 ... Image forming element P7 ... Liquid prism

Claims (8)

An insulating member having a bottom plate that is electrically insulating and capable of transmitting light;
A conductive fluid disposed on the surface of the bottom plate of the insulating member and capable of transmitting light;
An electrode member disposed on a surface facing the fluid of the insulating member;
Power supply means for applying a voltage to the fluid and the electrode member;
A transparent plate which is arranged on the surface of the fluid so as to be able to swing according to the flow of the fluid and which can transmit light;
A fluid prism characterized by comprising:   The fluid prism according to claim 1, wherein the electrode member is disposed on a back surface of the bottom plate.   The fluid prism according to claim 2, wherein a plurality of the electrode members are arranged. The fluid prism according to claim 2, wherein the transparent plate is supported by a rotatable support shaft . The insulating member has a cylindrical portion erected on the surface of the bottom plate,
The fluid is disposed inside the insulating member;
The fluid prism according to claim 1, wherein the electrode member is disposed on an outer peripheral surface of the cylindrical portion.   The fluid prism according to claim 5, wherein a plurality of the electrode members are arranged. The fluid prism according to claim 5, wherein the transparent plate is arranged in a state of floating inside the insulating member. The fluid prism according to any one of claims 5 to 7, wherein a second fluid having a refractive index different from that of the fluid is disposed above the fluid.

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