JP2002162507A - Optical element, illuminator and photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute an optical system asymmetrical with the optical axis, which can be changed in optical characteristics by electrowetting effect, using two kinds of liquids insoluble in each other. SOLUTION: This optical element has at least the first liquid 121, having electrical conductivity and the second liquid 122 having immiscibility with the first liquid and having a refractive index different from the refractive index of the first liquid, a container constituted to have a first surface 104 orthogonal with the optical axis 123 and a pair of second surfaces 105c and 105d, arranged to face each other to intersect with the front surface and to house the first and second liquids. Adsorption layers have absorptivity for at least one liquid of the first and second liquids are formed on the first surface and the second surface. A boundary 122d of at least the second surfaces of the first liquid and the second liquid intersecting with the adsorption surfaces is formed and the shape of the boundary is changed, according to a change in the impression voltage between a first electrode 125 for energizing the first liquid and a second electrode 103 disposed on the container side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical element utilizing an electrowetting effect (electrocapillary phenomenon), and an illumination device and a photographing apparatus using the optical element.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a varifocal lens in which the optical power of a lens is varied by changing the shape of the entrance surface of the lens or the optical characteristics inside the lens. Among these, some proposals have been made to vary the optical power of a lens whose optical power is not axially symmetric with respect to the optical axis, such as a so-called cylindrical lens having a cylindrical entrance surface or exit surface.

For example, Japanese Patent Publication No. 3-27081 discloses a varifocal lens in which a plate-like member having a rectangular opening is pressed against a transparent elastic body such as silicone rubber and a cylindrical lens is formed of silicone rubber protruding from the opening. It has been disclosed. In this case, the optical power of the cylindrical lens is made variable by the pressing amount of the plate member.

Japanese Patent Laid-Open Publication No. Hei 10-143906 discloses two sets of liquid crystal variable focus lenses that change optical power in one direction, and arranges these lenses orthogonally to control the light distribution of liquid crystal of each lens independently. By doing so, a varifocal lens capable of independently controlling the optical power in two directions has been proposed.

On the other hand, a variable focus lens using the electrowetting effect (electrocapillarity) is disclosed in International Patent No.
No./18456. In this method, a first liquid and a second liquid, which are insoluble and have different refractive indices, are sealed in a container to form a spherical lens, and a voltage is applied to one of the liquids to change the shape of the interface between the two liquids. By doing so, a variable focus lens is obtained.

[0006]

However, the variable various operation lens disclosed in Japanese Patent Publication No. 3-27081 requires an actuator for driving the plate-like member. Occurs,
There are drawbacks such as an optical power control error due to backlash of the driving force transmission system.

The variable focus lens proposed in Japanese Patent Application Laid-Open No. H10-143906 has drawbacks such as the occurrence of polarization and dispersion due to liquid crystal molecules and low transmittance, and its use is limited.

Further, the above-mentioned International Patent Publication No. 99/18456 only discloses a technique relating to an axisymmetric lens, but does not disclose any technique relating to a non-axisymmetric lens.

Accordingly, the present invention provides an optical system having an asymmetric optical axis using two types of liquids which are insoluble with each other, and further changes the shape of the interface between the two types of liquids by an electrowetting effect to improve the optical characteristics. It is an object to provide an optical element capable of obtaining a change.

[0010]

In order to achieve the above object, an optical element according to the present invention comprises a first liquid having conductivity or polarity and a first liquid which is not mixed with the first liquid. A second liquid, a first inner surface facing the optical axis direction, and a pair of second inner surfaces intersecting with the first inner surface and arranged opposite to each other, the first and second liquids And a container for accommodating the first inner surface and the second inner surface.
Forming an adsorbing layer having an adsorbing property on the second liquid on the inner surface of the first liquid and forming an interface between the first liquid and the second liquid intersecting at least the adsorbing layer on the second inner surface; The shape of the interface changes according to the change in the voltage applied between the first electrode for supplying electricity to the liquid and the second electrode provided on the container side.

Thus, the arrangement direction of the pair of second inner surfaces (the first direction orthogonal to the optical axis) and the direction orthogonal to the optical axis and the arrangement direction of the second inner surfaces (the optical axis and the first direction). (A second direction perpendicular to the direction), it is possible to realize an optical system with an optical axis asymmetrical shape in which the interface shape relating to the optical power is different, and the optical power is made variable without performing mechanical driving. An optical element can be obtained.

In the above invention, the outer edge of the adsorbing layer opposite to the first inner surface is formed in a substantially arc shape,
By making the interface substantially cylindrical, it is possible to obtain a cylindrical lens with variable optical power.

[0013] Further, by providing the second electrode on the inner surface of the container other than the second inner surface, the first electrode is provided.
It is possible to greatly change the optical power in the second direction as compared with the direction.

Specifically, for example, a second electrode is provided on the first inner surface side, and the first or second liquid is applied to the first or second liquid in accordance with a change in a voltage applied between the first and second electrodes. The shape of the interface can be changed by changing the area on the adsorption layer formed on the inner surface of the first electrode, or the second electrode can be connected to the first electrode.
And a third inner surface that intersects the second inner surface, and a portion of the interface that intersects the adsorbing layer formed on the third inner surface in response to a change in the voltage applied between the first and second electrodes. The shape of the interface may be changed by moving in the axial direction.

Further, by providing the optical element, a light source that emits illumination light irradiated through the optical element, and a power supply circuit that changes a voltage applied between the first and second electrodes, It is possible to realize an illumination device in which the irradiation range of the illumination light changes in response to a change in the voltage applied between the first and second electrodes (in particular, the light distribution angle in the second direction changes greatly). It is.

Further, the illumination device is provided in a photographing device having a photographing optical system capable of zooming, and a voltage applied between the first and second electrodes from a power supply circuit is changed according to zooming of the photographing optical system. By providing the control means for controlling the imaging device, it is possible to realize an imaging device with high illumination efficiency, in which the irradiation range of the illumination light changes optimally according to zooming (change in angle of view) of the imaging optical system.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIGS. 1 to 4 show the structure of an optical element according to a first embodiment of the present invention. First, FIG. 1 shows a configuration of a container that is a housing of the optical element. Here, the description will be made on the assumption that the optical axis 123 of the optical element extends in the up-down direction (x-axis direction).

In FIG. 1, reference numeral 101 denotes the entire optical element, and reference numeral 102 denotes a transparent acrylic transparent substrate having a ship-bottom concave portion 102a formed in the center. This recess 10
2a has a depth that changes gradually in the y-axis direction and has a uniform depth in the z-axis direction.

A transparent electrode 103, which is a thin-film resistor having a predetermined surface resistivity, is formed on the upper surface of the transparent substrate 102, and a transparent acrylic insulating layer 104 is provided on the upper surface thereof in close contact therewith. ing.

The insulating layer 104 is formed by dropping a replica resin at the center of the transparent electrode 103, pressing the replica resin with a glass plate to smooth the surface, and then irradiating with UV to cure.

On the upper surface of the insulating layer 104, four plate-like side members 105a to 105d are adhesively fixed. In FIG. 1, the side members 105b and 105c are drawn with imaginary lines so that the upper surface of the insulating layer 104 behind the side members 105b and 105c is exposed so that the structure of the water-repellent film described later can be understood.

A transparent acrylic upper cover 106 (see FIGS. 3 and 4) is adhered and fixed to the upper surfaces of these side members 105a to 105d, and a diaphragm having a rectangular opening at the center is further formed on the upper surface. A plate 107 (see FIGS. 3 and 4) is arranged.

In the above configuration, a closed space having a predetermined volume, that is, a container having a liquid chamber, surrounded by the insulating layer 104, the side members 105a to 105d, and the upper cover 106 is formed. The inner wall surface of the liquid chamber is subjected to the following surface treatment.

First, an adsorbing layer for adsorbing a second liquid, which will be described later, is provided in the center rectangular range of the upper surface (first inner surface facing the x-axis direction) of the insulating layer 104. In particular,
A water-repellent agent such as a fluorine compound is applied to form an extremely thin water-repellent film 111a.

The same effect can be obtained by irradiating the surface of the insulating layer 104 with plasma instead of using a fluorine compound to change the surface characteristics of the insulating layer.

A similar water-repellent agent is also applied to the lower portions of the inner wall surfaces (a pair of second inner surfaces) of the side members 105d, 105c, and the upper outer edge has a substantially arc-shaped water-repellent film 111b, 1b.
11c is formed. The shapes of the water-repellent films 111b and 111c are the same (combined). Then, the surface of the liquid chamber other than these three water-repellent regions is subjected to a hydrophilic surface treatment.

Further, a hole is formed in a part of the side member 105b, and a rod-shaped electrode (first electrode) 125 is inserted therein. The gap between the rod-shaped electrode 125 and the hole is sealed with an adhesive to maintain the airtightness of the liquid chamber.

Then, the transparent electrode 103 and the rod-like electrode 125
Is connected to the power supply circuit 126, and the voltage applied between both electrodes is changed by operating the switch 127 (in the present embodiment, the applied voltage becomes 0 when the switch is opened, and a predetermined voltage larger than 0 when the switch is closed). It is possible to set the voltage in the range).

The liquid chamber is filled with the following two types of liquids. First, the water-repellent film 11 on the insulating layer 104
A predetermined amount of the second liquid 122 (see FIGS. 3 and 4) is dropped on 1a.

This second liquid 122 is colorless and transparent,
Silicone oil having a specific gravity of 1.06 and a refractive index of 1.49 at room temperature is used. The second liquid is a water-repellent film 111
Because of high wettability (affinity) with respect to a, 111b, and 111c, it is contained in the liquid chamber in a shape along these water-repellent films.

The remaining space in the liquid chamber is filled with the first liquid 121 (see FIGS. 3 and 4). The first liquid 121 is an electrolytic solution (conductive or non-conductive) having a specific gravity of 1.06 and a refractive index of 1.38 at room temperature, in which water and ethyl alcohol are mixed at a predetermined ratio and a predetermined amount of salt is added. Polar liquid).

That is, in the present embodiment, as the first and second liquids 121 and 122, liquids having the same specific gravity, different refractive indices, and immiscible (insoluble) are selected. Therefore, both liquids 12
Reference numerals 1 and 122 form an interface having a shape to be described later, and each is independently contained in the liquid chamber without being mixed.

Next, the drop amount of the second liquid 122 will be described. The area of the water-repellent films 111b and 111c is S,
When the distance between the two water-repellent films 111b and 111c is m,
The space between the water-repellent films 111b and 111c forms a part of a substantially cylinder, and the volume V _S is V _S = S × m.

Therefore, in this embodiment, the volume of the second liquid 122 dropped on the upper surface of the insulating layer 104 is set to V _S. As a result, as described above, the second liquid 122 follows the water-repellent films 111a, 111b, and 111c, while the first liquid 121 fills the remaining space in the liquid chamber. As described later, a cylindrical planar interface is formed.

FIG. 2 shows the shape of the second liquid 122 in detail. The second liquid 122 is surrounded by four interfaces. The interface 122a is a surface in contact with the water-repellent film 111a formed on the upper surface of the insulating layer 104. The interface 12
2b is a water-repellent film 1 formed on the surface of the side member 105d.
11b, and similarly, the interface 122c is
5c is a surface in contact with the water-repellent film 111c formed on the surface of 5c. Further, the interface 122d is a surface that intersects the above three interfaces (that is, intersects the water-repellent films 111b and 111c) and is in contact with the first liquid 121.

The surface shape of the interface 122d is the second liquid 12
2 and the interfacial tension acting on the interface 122d. In the present embodiment, since the first liquid 121 and the second liquid 122 have the same density, both the liquids 121,
122 does not seem to be affected by gravity.
d is a shape having a minimum surface area, that is, a cylindrical surface and is stable.

FIGS. 3 and 4 show the optical element 10 of FIG.
1 is a plane containing the x and y axes (ie, interface 12
2D shows a cross section taken along the center of the cylindrical surface as 2d in the generatrix direction.

As can be seen from this figure, the first liquid 12
As described above, the interface 122d between the first liquid 122 and the second liquid 122 forms a cylindrical surface, and its cross section has a substantially arc shape. Becomes

Next, the change of the interface shape due to the electrowetting effect (electrocapillarity) will be described.
FIG. 3 shows the switch 127 in the open state, and the power supply circuit 126
, The voltage applied to both electrodes 125 and 103 is zero. At this time, the height of the center cross section of the interface 122d is h1, and the width of the bottom surface is W1, which is the same as the width of the water-repellent film 111a.

FIG. 4 shows a state in which the switch 127 is closed and a predetermined voltage is applied to both the electrodes 125 and 103 from the power supply circuit 126. At this time, a predetermined amount of electric charge proportional to the applied voltage is accumulated in the transparent electrode 103, and the same amount of the above electric charge and the opposite sign of electric charge are stored on the bottom surface of the first liquid 121, that is, in a portion facing the transparent electrode 103. Stored.
As a result, the center cross-sectional shape of the interface 122d changes to a height h2 (> h1) and a bottom width to W2 (<W1) due to the electrocapillary phenomenon as shown in the drawing.

FIG. 5 shows how the interface 122d between the two liquids is deformed according to the voltage applied to the optical element 101. FIG. 2A shows the case where the applied voltage is 0, and FIG.
As shown in (1), the interface 122d is a cylindrical surface having a predetermined curvature.

FIG. 5B shows a case where the applied voltage is low, for example, 100V. The interface deforming force due to the electrocapillary phenomenon occurs at a portion where the interface 122d is in contact with the insulating layer 104. That is, the sides 122e, 1 on both sides of the interface 122d
A force acts so that the 22f approach each other. Therefore,
The second liquid 122 deforms so that the width of the bottom surface decreases and the height increases, and the second liquid 122 has a cylindrical interface 122d.
Reduces the radius of curvature in the circumferential direction. This increases the optical power (1 / f: f is the focal length) in the y-axis direction (second direction).

On the other hand, the interfaces 122b and 122c are
Because it is constrained by the adsorption force of 11b and 111c, it resists the deforming action due to the electrocapillary phenomenon and tries to maintain the original shape. This resistance is due to the water repellent films 111b and 111c and the second
Although this embodiment depends on the wettability between the liquids 122, in the present embodiment, since the water-repellent film having a relatively low wettability is used, the interfaces 122b and 122c are slightly deformed from the original shape.

If a water-repellent material having extremely high wettability to the second liquid 122 is used as the water-repellent films 111b and 111c, it is possible to obtain an optical element in which the interfaces 122b and 122c hardly deform.

That is, by appropriately selecting the properties of the water-repellent films 111b and 111c, the curvature change ratio in the z-axis direction (first direction) and the y-axis direction (second direction) at the interface 122d when a voltage is applied. Can be set to a desired value.

FIG. 5C shows a case where the applied voltage is high, for example, 200 V. Compared to the case of FIG. 5B, the deformation of the cylindrical interface 122d further progresses, and The optical power further increases.

As described above, according to the present embodiment, the interface (cylindrical surface) 122d related to the optical power in the z-axis direction and the y-axis direction orthogonal to the x-axis direction and the z-axis direction which are the optical axis directions. Can be obtained with a simple configuration having an asymmetric optical axis (an optical system equivalent to a cylindrical lens) having a different shape. Moreover, its optical power (especially,
(optical power in the y-axis direction) can be changed without performing mechanical driving.

(Second Embodiment) FIGS. 6 to 8 show a first embodiment.
An embodiment in which the optical element 101 described in the embodiment is applied to an illumination device of a photographing device is shown. In the present embodiment, a so-called digital still camera is shown, in which an optical image is photoelectrically converted into an electric signal by an image pickup device such as a CCD and this is recorded as digital still image data.

Recently, a camera incorporating a photographing optical system having a zoom function and an electronic flash device (illumination device) has become popular, and the light distribution angle (irradiation range) of the flash device depends on the zoom state of the photographing optical system. ) Is also commercialized. In this embodiment, the optical element 101 is used as a light distribution angle adjusting unit of the flash device.

FIG. 6 shows the overall configuration of the photographing apparatus 150. In this drawing, reference numeral 141 denotes a photographing lens (photographing optical system) including a plurality of lens groups, which are not shown, a variable-magnification lens group, a variable-magnification actuator for driving the same, a focus-adjusting lens group, and a focus-adjustment actuator for driving the same. And an aperture mechanism, that is, a zoom function, an automatic focus adjustment function, and a light amount adjustment function.

Reference numeral 142 denotes an image sensor, which captures an image sensor such as a CCD and an analog image signal output from the sensor A
/ D conversion, AGC control, white balance, gamma correction,
A signal processing circuit for performing image processing such as edge enhancement is included.

A focus detection device 143 detects the distance to the subject using the principle of triangulation. As the focus detection device 143, a device that performs a phase difference detection type focus detection operation or the like may be used.

Reference numeral 144 denotes a flash device for illuminating the subject, and as shown in FIG. 7, a light source unit including a discharge arc tube (xenon tube or the like) 144a and a reflector 144b, and a light source unit disposed in front of the light source unit. Fresnel lens 144
and a condensing optical system including the optical element 101 disposed in front of the Fresnel lens 144c and a light emission control circuit (not shown). Then, from this flash device, illumination light having a predetermined light distribution characteristic is projected on the subject side as necessary.

The optical element 101 is arranged on the front side of the flash device 144, and adjusts the light distribution characteristics of the illumination light by changing its optical power as described above. That is, as described with reference to FIG. 5, since the optical power of the optical element 101 changes in accordance with the applied voltage, the optical element 101 is arranged on the front side of the flash device 144, and the applied voltage is controlled so that the light source It is possible to adjust the light distribution of illumination light projected from the section through the optical element 101 to the subject side to a desired characteristic.

By optimizing the light distribution characteristics of the flash device 144 in accordance with the zoom state (shooting angle of view) of the shooting lens 141, as described later, sufficient and efficient lighting for the shooting angle of view is achieved. Light distribution can be obtained, and a flash device 144 with high illumination efficiency can be realized.

As described in the first embodiment,
A voltage is applied to the two electrodes 103 and 125 of the optical element 101 from the power supply circuit 126.

Reference numeral 145 denotes a look-up table provided in a memory area inside the CPU 130.
The data for determining the output voltage of 26 is stored. That is, the value of the optical power with respect to the voltage applied to the optical element 101 is stored in a memory, and the applied voltage for obtaining a light distribution characteristic appropriate for the shooting angle of view of the shooting lens 141 during flash shooting is read out. Optical element 10
The light distribution characteristic of the illumination light is optimized by applying the value of “1”.

Reference numeral 151 denotes a display such as a liquid crystal display.
A subject image obtained through the image sensor 142 and various data relating to the shooting conditions of the camera are displayed.

A main switch 152 activates the CPU 130 from the sleep state to the program execution state.
A zoom switch 153 drives a variable power actuator in the taking lens 141 in response to a zoom switch operation of a photographer, and executes a variable power operation.

Reference numeral 154 denotes an operation switch group other than the above switches, which includes a photographing preparation switch, a photographing start switch, a photographing condition setting switch for setting a shutter time and an aperture value, and the like.

Reference numeral 155 denotes an external memory for recording a captured image signal. Specifically, a removable PC card type flash memory or the like is preferable.

FIG. 7 shows the operation of adjusting the light distribution angle of the optical element 101. FT indicates an imaging range when the imaging lens 141 is in a telephoto state, and FW indicates an imaging range when the imaging lens 141 is in a wide-angle state. Here, in order to effectively use the illumination light projected by the flash device 144, it is desirable that the irradiation range covers the entire photographing range and is as narrow as possible.

Therefore, in this embodiment, the photographing lens 14
The optical power of the optical element 101 is changed according to the zoom state of No. 1 to optimize the irradiation angle.

LT indicates an illumination range when the photographing lens 141 is in a telephoto state, and LW indicates an illumination range when the photographing lens 141 is in a wide-angle state.

The reason why a cylindrical lens is used for the optical element 101 is as follows. In the optical element according to the present embodiment, when it is desired to increase the change width of the optical power, the height h2 of the interface 122d at the time of applying a voltage is increased, so that the thickness of the entire optical element is also increased. On the other hand, since the discharge arc tube 144a, which is the light source of the flash device 144, is not a point light source but a linear or tubular light source, the size of the light emitting portion in the left-right direction is large. Therefore, for such a light source, it is difficult to control the light distribution angle in the left-right direction, so that the light distribution angle control only in the vertical direction may be used.

Therefore, a cylindrical lens is used for the optical element 101 disposed on the front side of the flash device 144, and the optical power in the generatrix direction (z-axis direction) of the cylindrical surface hardly changes, and the optical power in the direction orthogonal to this (y-axis direction) is changed. The optical power in the direction (1) is largely changed to suppress an increase in the interface height when a voltage is applied, thereby reducing the thickness of the optical element.

FIG. 8 shows an operation flow of the CPU 130 provided in the photographing apparatus 150 shown in FIG. Less than,
The control of the photographing device 150 will be described with reference to FIGS.

First, in step S101, it is determined whether or not the main switch 152 has been turned on. If the main switch 152 has not been turned on, the apparatus remains in the standby mode for waiting for the operation of various switches. If it is determined in step S101 that the main switch 152 has been turned on, the standby mode is released, and the process proceeds to the next step S102 and subsequent steps.

In step S102, the photographer sets the photographing conditions. For example, settings such as an exposure control mode setting (shutter priority AE, program AE, etc.), an image quality mode (large or small number of recording pixels, a large or small image compression ratio, etc.), a strobe mode (forcible light emission, light emission inhibition, etc.) are accepted.

Next, in step S103, it is determined whether or not the zoom switch 153 has been operated by the photographer. If the on operation has not been performed, the process proceeds to step S104. If the zoom switch 153 has been operated, the process moves to step S121.

In step S121, the zoom switch 1
The amount of operation (operation direction, ON time, etc.) of 53 is detected. In step S122, a target value of the focal length control of the photographing lens 141 is calculated based on the operation amount. Step S
In step 123, the variable magnification actuator of the photographing lens 141 is driven to control the focal length of the photographing lens to the value calculated in step S122.

In step S124, the voltage applied to the optical element 101 corresponding to the target value of the focal length control is read from the look-up table 145 in the CPU 130.

Then, in step S125, the output voltage of the power supply circuit 126 is controlled by the read applied voltage, and power supply to the optical element 101 is started. Thus, the optical power of the optical element 101 is controlled to a state according to the applied voltage. Then, the process returns to step S103.

Thus, while the operation of the zoom switch 153 is continued, the variable power control of the photographing lens 141 and the optical power control of the optical element 101 are repeatedly executed according to the operation amount, and the ON operation of the zoom switch 153 is completed. At this point, the process proceeds to step S104.

In step S104, it is determined whether or not the photographer has turned on a photographing preparation switch (denoted by SW1 in the flowchart of FIG. 7) in the operation switch group 154. If the ON operation has not been performed, the process returns to step S103, and the reception of the shooting condition setting and the determination of the operation of the zoom switch 153 are repeated. Step S1
If it is determined that the shooting preparation switch has been turned on in 04, the process proceeds to step S111.

In step S111, the image sensor 142 is driven to acquire a preview image. The preview image is used to properly set the shooting conditions for the final recorded image.
And an image acquired before shooting in order for the photographer to grasp the shooting composition.

In step S112, step S111
Recognize the light receiving level of the preview image acquired in step (1). Specifically, the maximum, minimum, and average output signal levels of the image signal output from the image sensor 142 are calculated, and the amount of light incident on the image sensor 142 is recognized. Also, it is determined whether or not to use the flash device according to the result of the light amount recognition.

In step S113, step S112
Based on the amount of received light recognized in step (1), a diaphragm mechanism provided in the photographing lens 141 is driven to adjust the aperture diameter.

In step S114, step S111
Is displayed on the display 151.
Subsequently, in step S115, the subject distance is detected using the focus detection device 143.

Subsequently, in step S116, the focus adjustment actuator in the photographing lens 141 is driven to perform a focusing operation. Thereafter, the process proceeds to step S117, in which it is determined whether or not the photographing switch (in FIG. 7, denoted as SW2) has been turned on. When the ON operation has not been performed, the process returns to step S111, and steps from acquisition of the preview image to focus driving are repeatedly executed.

As described above, if the photographer turns on the photographing switch while the photographing preparation operation is being repeatedly executed, the process jumps from step S117 to step S131.

In step S131, photographing is started. That is, the charge accumulation operation of the image sensor included in the image sensor 142 is started. In step S132, light emission control of the flash device 144 is performed.

Then, in step S133, after a predetermined exposure time has elapsed, the charge accumulation operation of the image sensor 142 is stopped. In step S134, step S133
Read out the charge accumulated at
The read analog signal is input to the signal processing circuit. In step S135, the signal processing circuit performs A / D conversion on the input analog image signal and performs AGC control.
Image processing such as white balance, gamma correction, and edge enhancement is performed, and, if necessary, JPEG compression or the like is performed by an image compression program stored in the CPU 130.

Next, in step S136, the image signal obtained in step S135 is recorded in the memory 155. In step S137, first, the preview image displayed in step S114 is deleted, and the image signal obtained in step S135 is displayed again on the display 151.

Subsequently, in step S138, the power supply output from the power supply circuit 126 is stopped, and in step S139, a series of photographing operations ends.

As described above, in this embodiment, the interface 12 of the optical element 101 is changed according to the zoom state of the taking lens 141.
Since the shape of 2d is changed and the light distribution of the illumination light from the flash device 144 is optimized, insufficient exposure in each zoom state can be prevented. Lighting can be performed.

Further, since the optical element 101 is thin despite the large change rate of the optical power as described above, it is effective for reducing the thickness of the flash device 144 and, further, for reducing the size of the entire photographing apparatus.

Further, as described in the first embodiment, no mechanical driving means is required for controlling the optical power of the optical element 101, so that the camera can be made more compact and cost-effective.

In this embodiment, the case where the flash device 144 including the optical element 101 is used for a digital still camera has been described. However, similar lighting devices include a video camera light and an autofocus light projecting device. It can also be used as another lighting device.

(Third Embodiment) FIGS. 9 to 12 show the structure of an optical element according to a third embodiment of the present invention. Here, the description will be made on the assumption that the optical axis 223 of the optical element extends in the up-down direction (x-axis direction).

FIG. 9 shows the structure of a container which is a housing of the optical element of this embodiment. In this drawing, reference numeral 201 denotes the entire optical element, and reference numeral 202 denotes a transparent acrylic lower cover. On the upper surface of the lower cover 202, four plate-like side members 205a to 205d are adhesively fixed. Note that the side members 205b and 205c are omitted so that the structure of the water-repellent treatment film described later can be understood.

On the front surface of the side member 205a, a flat electrode 203a and an insulating layer 204a are formed. The side member 205b shown in FIGS. 11 and 12 has a symmetric shape with the side member 205a. A transparent acrylic upper cover 206 (see FIGS. 11 and 12) is bonded and fixed to the upper surfaces of these four side members 205a to 205d, and further has a rectangular opening in the center on the upper surface. An aperture plate 207 (see FIGS. 11 and 12) is arranged.

In the above configuration, a closed space having a predetermined volume surrounded by the lower cover 202, the side members 205a to 205d, and the upper cover 206, that is, a container having a liquid chamber is formed. Then, the wall surface of the liquid chamber is subjected to the following surface treatment.

First, an adsorbing layer for adsorbing a second liquid, which will be described later, is provided in a central rectangular range on the upper surface (first inner surface) of the lower cover 202. Specifically, similarly to the first embodiment, a water-repellent treatment agent such as a fluorine compound is applied,
An extremely thin water-repellent film 211a is formed. The same effect can be obtained by irradiating the upper surface of the insulating layer formed on the upper surface of the lower cover 202 with plasma instead of using the fluorine compound to change the surface characteristics of the insulating layer.

A similar water-repellent agent is also applied to the lower portions of the inner wall surfaces (third inner surfaces) of the side members 205a and 205b to form rectangular water-repellent films 211d and 211e (see FIGS. 11 and 12). It is formed. The water-repellent films 211d and 211e have the same shape.

Further, the same water-repellent treatment agent is applied to the lower portion of the inner wall surface (second inner surface) of the side members 205c and 205d, and the upper edge of the water-repellent film 211b is substantially arc-shaped.
211c is formed. These water repellent films 211b, 211
c has the same shape. The surface of the liquid chamber other than these five water-repellent regions is subjected to a hydrophilic surface treatment.

Further, a hole is formed in a part of the side surface member 205b, and the rod-shaped electrode 225 is inserted therein. And
The gap between the rod-shaped electrode 225 and the hole is sealed with an adhesive, so that the airtightness of the liquid chamber is maintained.

The electrodes 203a and 203b and the rod-like electrode 125
Is connected to the power supply circuit 226, and the applied voltage between both electrodes is changed by operating the switch 227 (in the present embodiment, the applied voltage becomes 0 when the switch is opened and becomes 0 when the switch is closed).
It is possible to set a voltage in a larger predetermined voltage range).

In the liquid chamber configured as described above, two kinds of liquids similar to those in the first embodiment are filled and stored. First,
On the water-repellent film 211a on the lower cover 202, a second liquid 222 made of silicone oil (see FIGS. 11 and 1)
2) is dropped by a predetermined amount. This second liquid 22
2 has high wettability (affinity) with respect to the water-repellent films 211a to 211e, and therefore fits in the liquid chamber in a shape along these water-repellent films.

On the other hand, the remaining space in the liquid chamber is filled with a first liquid 221 (FIGS. 11 and 12) composed of an electrolytic solution. Both liquids form an interface of a predetermined shape, and each is independently contained in the liquid chamber without being mixed.

The drop amount of the second liquid 222 is made the same as the volume of the space between the water-repellent films 211b and 211c, as in the first embodiment. As a result, the second liquid 222 follows the water-repellent films 211a to 211e while the first liquid 22
1 fills the remaining space in the liquid chamber,
Between 222, a cylindrical interface is formed as described later.

FIG. 10 shows the shape of the second liquid 222 in detail. The second liquid 222 is surrounded by five interfaces. The interface 222a is a surface in contact with the water-repellent film 211a formed on the upper surface of the lower cover 202. The interface 22
2b and 222c are in contact with the water-repellent films 211b and 211c formed on the surfaces of the side members 205d and 205c, and similarly, the interfaces 222d and 222e are in contact with the side members 205a and 205c.
b comes into contact with the water-repellent films 211d and 211e formed on the surface.

On the other hand, the interface 222f is the same as the four interfaces 20f.
5b to 205e (that is, the water-repellent film 211b,
211c, 211d, 211e) and the surface in contact with the first liquid 211, and the surface shape is determined by the balance between the gravity acting on the second liquid 222 and the interfacial tension acting on the interface 222f. In the present embodiment, the first liquid 221
And the second liquid 222 have the same density.
Apparently, gravity does not act on 1 and 22, and the interface 222f becomes a shape having a minimum surface area, that is, a cylindrical surface, and is stabilized.

FIG. 11 shows the optical element 201 shown in FIG.
Is a cross section taken along a plane including the x-axis and the y-axis (that is, the center in the generatrix direction of the interface 222f that is a cylindrical surface).

As can be seen from this figure, the first liquid 21
The interface 222f between the first and second liquids 222 forms a cylindrical surface as described above, and has a substantially arc-shaped cross section. Then, the planar electrodes 203a and 203b
The point that the initial shape of the interface 222f can be freely determined by appropriately setting the inclination angle on the inner surface side of the side members 205a and 205b having the following configuration is different from that of the first embodiment.

Next, the change of the interface shape due to the electrowetting effect (electrocapillary phenomenon) will be described.
FIG. 11 shows a state in which the switch 227 is open,
6 shows a case where the voltage applied between the rod-shaped electrode 225 and the electrodes 203a and 203b is 0. At this time, the interface 22
The height of the central section of 2f is t1.

FIG. 12 shows a state where the switch 227 is closed and a predetermined voltage is applied to the rod-shaped electrode 225 and the electrodes 203a and 203b by the power supply circuit 226. At this time, a predetermined amount of electric charge proportional to the applied voltage is accumulated in the electrodes 203a and 203b, and the side of the first liquid 221, that is, the portion facing the electrodes 203a and 203b has the same amount as the above electric charge and the opposite sign. Charge is accumulated. As a result, the height of the central cross-sectional shape of the interface 222f changes to t2 (> t1) as shown in the figure due to the electrocapillary phenomenon.

FIG. 13 shows how the interface 222f between the two liquids is deformed according to the voltage applied to the optical element 201. FIG. 10A shows the case where the applied voltage is 0, and the interface 222f is a cylindrical surface having a predetermined curvature as shown in FIG.

FIG. 13B shows a case where the applied voltage is low, for example, 100 V. The interface deforming force due to the electrocapillary phenomenon is generated at a portion where the interfaces 222d and 222e are in contact with the insulating layers 203a and 203b. That is, a force acts such that both the upper sides of the interfaces 222d and 222e approach the lower cover 202. Therefore, the second liquid 222 is deformed such that the height of the side surfaces on both sides thereof is reduced and the height of the center is increased, and the radius of curvature in the circumferential direction of the cylindrical interface 122d is reduced. ,
Optical power increases.

On the other hand, the interfaces 222b and 222c are
11b and 211c are restrained by the attraction force,
It resists the deformation effect of the electrocapillary phenomenon and tries to maintain its original shape. Although this resistance depends on the wettability between the water-repellent films 211b and 211c and the second liquid 222, in the present embodiment, since the water-repellent film having relatively low wettability is used, the interfaces 222b and 222c are used. Slightly deforms from its original shape.

If a water-repellent material having very high wettability of the water-repellent films 211b and 211c to the second liquid 222 is used, it is possible to obtain an optical element in which the interfaces 222b and 222c are hardly deformed.

That is, by appropriately selecting the properties of the water-repellent films 211b and 211c, the interface 222f when a voltage is applied can be obtained.
In the z-axis direction (first direction) and the y-axis direction (second direction).
Direction) can be set to a desired value.

FIG. 13C shows the case where the applied voltage is high, for example, 200 V, and the deformation of the cylindrical interface 222f further progresses as compared with the case of FIG. 13B.

According to this embodiment, the same effects as those of the first embodiment can be obtained, and the initial shape of the interface 222f can be set to a desired shape, so that the degree of freedom in optical design is increased.
The thickness of the optical element can be further reduced.

Further, the optical element 201 of the present embodiment can be used for a lighting device such as a photographing device as shown in the second embodiment, as in the first embodiment.

In the first and second embodiments, the case has been described where the first inner surface corresponding to the bottom surface of the container is formed of a flat surface. However, the first inner surface may be formed of a curved surface such as a cylindrical surface. Good.

[0117]

As described above, according to the present invention,
An arrangement direction of the pair of second inner surfaces (a first direction orthogonal to the optical axis) and an optical axis and a direction orthogonal to the arrangement direction of the second inner surfaces (a second direction orthogonal to the optical axis and the first direction). ), The interface shape related to the optical power is different, and an optical system asymmetric with respect to the optical axis can be realized. In addition, it is possible to obtain an optical element capable of changing its optical power without performing mechanical driving.

In the above invention, the outer edge of the second inner surface of the adsorbing layer opposite to the first inner surface is formed in a substantially circular arc shape, and the interface is formed as a substantially cylindrical surface. It is possible to obtain an optical system equivalent to a variable cylindrical lens.

Further, by providing the second electrode on the inner surface of the container other than the second inner surface, the first electrode is provided.
The optical power can be largely changed in the second direction as compared with the direction.

Further, by providing the optical element, a light source that emits illumination light radiated through the optical element, and a power supply circuit that changes a voltage applied between the first and second electrodes, An illumination device in which the irradiation range of the illumination light changes in response to a change in the voltage applied between the first and second electrodes (in particular, the light distribution angle in the second direction greatly changes) can be realized. .

Further, this illumination device is provided in a photographing device having a photographing optical system capable of zooming, and the voltage applied between the first and second electrodes from the power supply circuit is changed according to the zooming of the photographing optical system. By providing the control means for performing the control, it is possible to realize an imaging device with high illumination efficiency in which the irradiation range of the illumination light changes optimally in accordance with zooming (change in the angle of view) of the imaging optical system.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a container used for an optical element according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing the shape of a second liquid constituting the optical element of the first embodiment.

FIG. 3 is a cross-sectional view of the optical element of the first embodiment (with no voltage applied).

FIG. 4 is an optical element (voltage applied state) of the first embodiment.
FIG.

FIG. 5 is a perspective view showing a shape change of a second liquid in the optical element of the first embodiment.

FIG. 6 is a block diagram illustrating a configuration of a photographing device and a flash device according to a second embodiment of the present invention.

FIG. 7 is a conceptual diagram showing the relationship between the shooting angle of view of the shooting device of the second embodiment and the light distribution of a flash device.

FIG. 8 is a flowchart showing the operation of the imaging device according to the second embodiment.

FIG. 9 is a perspective view showing a configuration of a container used for an optical element according to a third embodiment of the present invention.

FIG. 10 shows a second example of the optical element according to the third embodiment.
FIG.

FIG. 11 is a cross-sectional view of the optical element according to the third embodiment (with no voltage applied).

FIG. 12 is a cross-sectional view of the optical element (voltage applied state) according to the third embodiment.

FIG. 13 is a perspective view showing a shape change of a second liquid in the optical element according to the third embodiment.

[Explanation of symbols]

101, 201: Optical element 102: Transparent substrate 103: Transparent electrode 104: Insulating layer 105a, 105b, 105c, 105d, 205a,
205b, 205c, 205d ... side surface members 111a, 111b, 111c, 211a, 211b,
211c, 211d, 211e ... water-repellent film 121, 221 ... first liquid 122, 222 ... second liquid 122d, 222f ... (two liquid) interface 123, 223 ... light Axis 125, 225: Rod-like electrode 126, 226: Power supply means 101, 201: Optical element 102: Transparent substrate 202: Lower cover 203a, 203b: Electrode 150: Photographing device 141: photographing lens 144: flash device

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Eriko Kawanami 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H044 DA02 DB00 DC01 DC10

Claims (9)

[Claims] 1. A first liquid having conductivity or polarity, a second liquid that does not mix with the first liquid, a first inner surface facing the optical axis direction, and the first liquid A container configured to include at least a pair of second inner surfaces intersecting with the inner surface and disposed to face each other, and having a container for storing the first and second liquids, wherein the first inner surface and the second Forming an adsorbing layer having an adsorbing property on the second liquid on an inner surface thereof;
Forming an interface between the first liquid and the second liquid at least intersecting with the adsorption layer on the second inner surface, and a first electrode for supplying electricity to the first liquid and a second electrode provided on the container side. An optical element, wherein the shape of the interface changes according to a change in a voltage applied to the electrodes. 2. The method according to claim 1, wherein an outer edge of the second inner surface of the attraction layer opposite to the first surface is formed in a substantially arc shape, and the interface is formed as a substantially cylindrical surface.
An optical element according to item 1. 3. The optical element according to claim 1, wherein the second electrode is provided on a surface other than the second inner surface of the inner surface of the container. 4. The liquid supply device according to claim 1, wherein the second electrode is provided on the first inner surface side of the inner surface of the container, and the one liquid is changed according to a change in a voltage applied between the first and second electrodes. 4. The optical element according to claim 3, wherein the shape of the interface changes by changing the area on the adsorption layer formed on the first inner surface. 5. 5. The method according to claim 1, wherein the second electrode is provided on a third inner surface of the inner surface of the container that intersects the first and second inner surfaces, and a voltage applied between the first and second electrodes is provided. 4. The shape of the interface changes according to a change in the shape of the interface, by moving a portion of the interface that intersects the adsorption layer formed on the third inner surface in the optical axis direction. Optical element. 6. An optical element according to claim 1, a light source that emits illumination light irradiated through the optical element, and a power supply that changes a voltage applied between the first and second electrodes. A lighting circuit, wherein a voltage applied from the power supply circuit to the first and second electrodes is changed to change an irradiation range of illumination light. 7. The lighting device according to claim 6, wherein the light source is formed in a tubular shape extending in a direction in which the second inner surface is opposed to the light source. 8. A photographing apparatus comprising the lighting device according to claim 6. 9. An imaging optical system capable of zooming, and control means for changing a voltage applied between the first and second electrodes from the power supply circuit according to zooming of the imaging optical system. The photographing apparatus according to claim 8, wherein: