JP2013101227A - Liquid optical element and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for making fast a driving speed which is apt to decrease owing to friction between an insulating film of an electrode and a liquid with respect to a liquid optical element such as a liquid lens using driving force of an EW type driving pump part.SOLUTION: The liquid optical element has an optical effective part and a plurality of driving pump parts 108. A driving pump part has a holding part 106 holding ends of interfaces 103b, 103c, and 103d between liquids 101, 102 which are not mixed together,and an insulating electrode 104 arranged for the holding part. An end of an interface contacting the electrode 104 is displaced by controlling a voltage applied to the electrode to move the liquids, and the state of the optical effective part where a plurality of liquids including the liquids 101, 102 present communicating with the respective driving pump parts is changed to change optical characteristics.

Description

The present invention relates to an optical element such as a power variable element, and more particularly to a liquid optical element such as a liquid lens that changes power using liquid and a control method thereof.

Conventionally, many power variable elements that change optical power with one element have been proposed. Among them, a liquid lens that changes the interface between two liquids has excellent characteristics such as no dependency on polarization. As a method of changing the interface, there are a method in which a pump is provided outside and the amount of liquid inside is changed by the pump, and a method using electrowetting (hereinafter also referred to as EW) phenomenon. Here, in the EW phenomenon, as shown in FIGS. 14A and 14B, two liquids are composed of a conductive liquid 2001 and a non-conductive liquid 2002, and the conductive liquid 2001 and the electrode 2003 are insulated. A voltage is applied through the film 2004 to change the contact angle α between the liquid and the insulating film. The driving force of the liquid in the EW phenomenon increases in proportion to the voltage to be applied and the length of the portion where the two liquids 2001 and 2002 are in contact with each other (hereinafter also referred to as the tangential length). As another example of using the EW phenomenon, the liquid that changes the shape of the interface between the two liquids moved by the EW phenomenon and changes the optical power of the lens effective portion including the interface. A lens has been proposed (see Patent Document 1).

In the invention described in Patent Document 2, the interface between the two liquids is displaced using the EW phenomenon in the drive pump unit, thereby controlling the position of the interface between the two liquids in the lens effective portion, thereby adjusting the phase of the transmitted light. It is changing. At this time, in order to increase the force for moving the liquid by the EW phenomenon, the number of electrodes is increased by dividing the electrode, and as a result, the tangential length of the drive pump unit is increased, and the driving force by the EW phenomenon is increased. Further, in the invention described in Patent Document 3, in order to realize high-speed driving of the liquid lens, the lens portion is made into a Fresnel lens, and electrodes are arranged on each ring of the Fresnel lens. By adopting such an electrode arrangement, as in the invention of Patent Document 2, the tangent length with respect to the total amount of the liquid is lengthened, and the driving force is increased to realize high-speed driving.

EP1870741A1 JP 2010-79297 A Special table 2007-519025 gazette

As shown in FIG. 14C, the EW phenomenon increases the contact angle α at the interface by applying a voltage. However, in the region where the voltage is low, as shown in FIG. 14C, the contact angle α hardly changes with respect to the applied voltage (that is, has a dead zone). This reason is considered to be due to friction between the two liquids and the insulating film in contact with the liquids. Due to this friction, there is a phenomenon that the interface drive becomes slow at a low voltage. For this reason, the drive becomes slower as it is desired to give a minute change in focal length. On the contrary, when a high voltage (a voltage sufficiently larger than the threshold value) is applied, the static friction can be overcome, so that a very high-speed driving is possible. In addition, the change in the contact angle α has a so-called hysteresis indicating a different change mode between rising and falling. This hysteresis depends on the physical properties of the insulating film and the two liquids and is difficult to completely eliminate.

In view of these problems, the present invention is relatively insensitive to changes in minute optical characteristics (focal length, etc.) while applying a discrete voltage including a voltage that is large enough to neglect a decrease in response speed due to frictional force. A technique capable of providing even a large change in optical characteristics is provided. In addition, by appropriately applying the applied voltage control using this technique, it is possible to reduce the hysteresis regardless of the physical properties of the liquid and the insulating film.

The liquid optical element of the present invention has an optically effective portion that has a function of changing optical characteristics and a plurality of drive pump portions. Each drive pump unit has a holding unit that holds an end portion of an interface formed by a conductive liquid and a non-conductive liquid that are immiscible with each other, and is disposed with respect to the holding unit and is provided for the conductive and non-conductive liquids. And an insulated electrode. Then, by controlling the voltage applied to the electrode, the electrowetting phenomenon displaces the end of the interface in contact with the electrode to move the conductive and nonconductive liquid sandwiched between the holding part and the electrode. Let As a result, the optical characteristics are changed by changing the state of the optically effective part where at least two kinds of non-mixed liquids including the conductive and non-conductive liquids existing in communication with each drive pump part are present. It is done. In addition, the voltage applied to the electrodes of each drive pump unit is set to at least two discrete voltage values within the operating range, and the applied voltage to the electrodes of the plurality of drive pump units is controlled independently, thereby optically effective. The state of the interface at the part is changed.

According to the present invention, in the liquid optical element such as a liquid lens that moves the liquid between the optically effective portion that communicates with the plurality of drive pump portions and changes the state of the liquid interface in the optically effective portion due to the EW phenomenon. The applied voltage to the electrodes of each drive pump unit is a plurality of discrete voltage values. The applied voltages are controlled independently. Accordingly, it is possible to realize high-speed driving in almost all optical characteristic variable ranges (focal length variable ranges, etc.). Furthermore, if the applied voltage is appropriately controlled, hysteresis can be reduced in almost all optical characteristic variable ranges.

Sectional drawing of the liquid lens of 1st Example of a liquid optical element. The front view of the liquid lens of 1st Example. The figure showing another example of the relationship between the applied voltage and optical power by the difference in the number of drive pump parts in 1st Example, and the relationship between an applied voltage and optical power. The figure which shows the liquid lens of 2nd Example. The figure showing the hysteresis in the relationship between an applied voltage and optical power. The front view which shows another example of the electrode structure of 2nd Example, and the liquid lens of 3rd Example. FIG. 10 is a diagram showing the relationship between the number of drive pump units driven and the optical power in the liquid lens of the third example. The schematic diagram showing operation | movement of the EW drive pump part in 3rd Example. The figure which shows the other example of the liquid lens of 3rd Example, and the example of the drive method of a drive pump part. The figure explaining the structure of the digital video camera of 4th Example, and the driving method of wobbling. The figure which shows the external appearance and block configuration of the digital still camera of 5th Example. The block block diagram of the mobile telephone with a camera of 6th Example. The figure which shows the external appearance of the surveillance camera of 7th Example, and its block configuration. The figure which shows the change of the contact angle by EW phenomenon, and the relationship between the applied voltage and contact angle change in EW phenomenon.

The feature of the present invention is that the voltage applied to the drive pump unit of the liquid optical element is a plurality of discrete voltages within the operating range, and the plurality of drive pump units to which the voltage is applied are controlled independently of each other. It is to change the state of the interface in the part. Here, the voltage in the operating range is a voltage value within a range in which the state of the interface in the optically effective portion can be effectively established, and is typically a voltage that is 0 or more and a breakdown voltage or less. . However, since there is usually a certain margin for the breakdown voltage, the voltage takes into account the margin. Further, in the drive pump unit, an interface is formed between the two liquids, and the two liquids are moved by moving the interface to change the state of the interface of the optically effective unit communicating with the drive pump unit. The interface of the optically effective portion may be formed between the two liquids. For example, the interface may be formed between the two liquids by sandwiching another liquid that is not mixed with the two liquids. . Further, the optically effective portion responsible for the function of changing the optical characteristics can be various in addition to those having the lens function described later, and is achieved by the change in the state of the two liquids communicating with the drive pump portion. Any function that can be performed (for example, phase modulation or intensity modulation of transmitted light) may be used. In the liquid optical element having such a configuration, if the voltage applied to the plurality of drive pump units is appropriately selected from 0 and a value equal to or higher than the threshold value, the dead zone can be avoided, the speed is relatively high, and the change from the small optical characteristic is large. It is possible to realize a change up to a change in optical characteristics. In addition, since analog (continuous) voltage application is not digital but (binary-selective) voltage application, the occurrence of hysteresis can be suppressed as a result. Based on the above concept, the liquid optical element of the present invention has the basic configuration described in the means for solving the above-mentioned problems. In such a liquid optical element control method, the voltage applied to the electrodes of the plurality of drive pump units is selected from at least two discrete voltage values within the operating range and controlled independently.

Hereinafter, specific examples will be described with reference to the drawings.
(First embodiment)
The first embodiment of the present invention will be described with reference to FIGS. 1 and 2, among the interfaces 103 of two liquids (one is a conductive liquid and the other is a non-conductive liquid) 101 and 102, 103 a constitutes an interface of an optically effective portion that assumes an optical property varying function. The parts 103b, 103c, and 103d form a part that generates liquid movement (hereinafter also referred to as an EW drive pump part or a drive pump part). Here, the EW drive pump units 108a to 108c include liquid interfaces 103b, 103c, and 103d, electrodes 104a, 104b, and 104c, an insulating film 105 that insulates the electrodes from the liquid, and protrusions 106b, 106c, and 106d. . For example, when a voltage is applied to the electrode 104a, the contact angle between the liquid interface 103b and the insulating film 105 changes. Here, one end of the liquid interface 103b is in contact with the protrusion 106a. Since the liquid interface 103b is fixed by the protrusion 106a which is a holding portion for holding the end of the liquid interface 103b, the position of the end does not move. On the other hand, the contact angle with the insulating film 105 changes at the end of the liquid interface 103b on the electrode 104b side by application of voltage. As a result of this process, for example, the position of the liquid interface 103b changes from the state of FIG. 1 (a) to the state of FIG. 1 (b). At this time, since the total amount of the liquids 101 and 102 in the housing 107 for containing and sealing the liquid is constant, a flow (see an arrow) occurs in the liquid. By this flow, pressure is applied to the interface 103a which is in the optically effective portion and the end portion is fixed by the protrusion 109, and the shape of the interface 103a changes. As described above, the liquid optical element of this embodiment includes the optically effective portion and a plurality of drive pump portions. Each drive pump unit includes a holding unit that holds an end portion of an interface formed by two liquids that are immiscible with each other, and an electrode that is disposed with respect to the holding unit and insulated from the two liquids. By controlling the voltage applied to the electrode, the electrowetting (EW) phenomenon causes the end of the interface in contact with the electrode to be displaced, and the two liquids sandwiched between the holding part and the electrode are moved, The optical characteristics can be changed by changing the state of the optically effective portion where there are at least two kinds of unmixed liquids including the two liquids communicating with the drive pump.

As shown in FIG. 2, the EW drive pump units 108a to 108c are arranged outside the optically effective portion (interface) 103a. The drive pump unit may be disposed anywhere outside the optically effective portion (interface) 103a, but it is desirable that the driving pump portion be as close to the optically effective portion as possible in view of the flow of liquid. In the present embodiment, the drive pump units 108a to 108c are equal in size, and the liquid flow rates when driven at the same voltage are the same. 2 is a cross-sectional view of FIG.

Here, consider a case where the shape of the interface 103a in the optically effective portion is minutely changed. It is assumed that the change in the optical power of the liquid lens due to the change in the interface 103a is proportional to the voltage applied to the electrodes 104a to 104c and the number of EW drive pump units that drive the liquid (see FIG. 3A). As shown in FIG. 3A, when a certain optical power change φ is given, when one EW drive pump unit (for example, only 108a) is moved, the necessary applied voltage is V1. On the other hand, when operating the three EW drive pump units 108a to 108c, a voltage V2 smaller than V1 is applied. At this time, when a voltage is applied to all three EW drive pump units, a voltage slightly exceeding the threshold value Vt is applied as shown in FIG. This threshold value Vt is a value determined by the physical properties of the two liquids 101 and 102 and the insulating film 105, and depends on the static friction force acting between them. For this reason, when the voltage V2 is applied and when the voltage V1 is applied, the interface moves faster when the voltage V1 that exceeds the static friction force with a larger force is applied, resulting in higher speed. Lens driving can be achieved.

When the number of electrodes is as small as three as shown in FIG. 1, when the applied voltages are only 0 and V1, the liquid lens can be changed only to four optical power states including the initial state. Therefore, as shown in FIG. 3B, the voltage state may be changed by discretely applying three or more voltages such as 0, V1, and V3. Thus, by applying voltages discretely, the number of optical powers that the liquid lens can take can be increased. At this time, the applied voltage is larger than the threshold value Vt, and if possible, it is desirable to select a voltage value of 1.2 times or more the threshold value Vt. Further, the applied voltage may not include 0V. For example, non-zero voltages V4 and V5 may be selected and driven.

As can be seen from the above description, high-speed driving of the liquid lens can be achieved by arranging a large number of EW drive pump units with a small liquid flow rate and driving these drive pump units with a large voltage sufficiently larger than the threshold value Vt. . Furthermore, it is possible to realize both small optical characteristic changes and large optical characteristic changes. More specifically, for example, the applied voltage control unit stores a table representing the correspondence between each value of the optical power and the applied voltage value of each drive pump unit, and from the control unit that controls the entire apparatus. When a certain value of optical power is required, application voltage control is performed such that a voltage corresponding to the optical power is applied to each drive pump unit with reference to the table.

(Second embodiment)
The second embodiment of the present invention will be described with reference to FIG. 4A and 4B are cross-sectional views of the liquid lens in the second embodiment, and FIG. 4C is a front view of the liquid lens in the second embodiment. In the second embodiment, unlike the first embodiment, the EW drive pump section is arranged to surround the optical effective section of the liquid lens in multiple layers around the optical axis of the liquid lens. As shown in FIG. 4, ring-shaped EW drive pump portions 508a to 508c are arranged so as to surround the interface 503a of the optically effective portion. The EW drive pump units 508a to 508c are configured by liquid interfaces 503b to 503d, electrodes 504a, 504b, and 504c, an insulating film 505, and protrusions 506a, 506b, and 506c, similarly to the EW drive pump unit of the first embodiment. . As in the first embodiment, the liquid interfaces 503b to 503d are changed by applying voltages to the electrodes 504a to 504c, and the liquid interfaces of the optically effective portion are pressed by pressing the liquids 501 and 502 accommodated in the sealed casing 507. The shape of 503a changes (see FIG. 4B).

Thus, by disposing the EW drive pump units 508a to 508c so as to surround the optical effective unit, the distance between the interface 503a of the optical effective unit and the EW drive pump units 508a to 508c can be shortened. For this reason, an unnecessary liquid flow does not occur, and a smooth change can be given to the interface 503a. In addition, since the EW drive pump units 508a to 508c have a ring shape, a liquid flow isotropically occurs with respect to the liquid interface 503a. Therefore, it is possible to suppress the liquid interface 503a from greatly changing from the spherical surface (aspherical).

Here, when the voltages applied to the electrodes are 0 and V1, the relationship between the applied voltage and the optical power of the liquid lens is as shown in FIG. Here, it is assumed that a voltage V2 other than 0 and V1 (0 <V2 <V1) is applied. At this time, as described above, hysteresis occurs between the applied voltage and the optical power in the liquid lens, and different optical powers are shown at the rise and fall (φu and φd). This hysteresis is caused by the hysteresis (advance angle / retreat angle) of the contact angle θ generated by the material of the liquids 501 and 502 and the insulating film 505. It is difficult to make this hysteresis completely zero, and as long as the applied voltage is applied in an analog manner, hysteresis occurs in the liquid lens. On the other hand, in the liquid lens in the present embodiment, only two voltages 0 and V1 (voltage outside the hysteresis region) are applied. For this reason, the advancing angle and the receding angle of the contact angle are equal to each other, and the optical power generated by driving each drive pump unit is only φ0 and φ in FIG. 5, and the occurrence of hysteresis can be suppressed. In this way, in this embodiment, since two digital voltages are applied without applying an analog voltage, the occurrence of a difference in contact angle caused by an intermediate voltage is suppressed, resulting in a reduction in hysteresis. can do. However, when three or more voltages are applied digitally, the liquid lens can be driven at high speed, but hysteresis (φd and φu) as shown in FIG. 5 may occur. Therefore, it is necessary to determine the mode of applied voltage control according to the required specifications. For example, in order to suppress hysteresis, the selection range of the applied voltage is limited, but there is a control mode in which a discrete voltage selected from a region where hysteresis is small is applied. That is, when three or more voltages are applied as shown in FIG. 3B of the first embodiment, the generation of hysteresis is reduced by selecting a voltage other than the maximum and minimum voltages from a region having a small hysteresis. Is possible.

By the way, in the present embodiment, the respective electrodes 504a to 504c produced in a ring shape are connected. For example, as shown in FIG. A large number of EW drive pump units may be configured point-symmetrically around the optical axis of the liquid lens, and each may be driven individually. In this case, for example, by increasing the number of EW drive pump units to be driven in order from the electrode 801a, a liquid lens capable of giving a total of nine states of optical power while preventing the occurrence of hysteresis can be configured. Of course, the driving order is not limited to this, and may be selected at random, for example. That is, for example, in the case of one drive, only the electrode 801a may be moved, and in the case of three drives, the electrodes 801a, c, d may be moved, or the electrodes 801b, g, h and the electrodes 801c, d, f may be moved. In this way, any number of drive pump units to be moved may be moved as long as they match.

By disposing the EW drive pump portion in a ring shape in this way, it is possible to make the liquid flow uniform and change the optical power without breaking the shape of the liquid interface of the optically effective portion. Also, hysteresis can be reduced by driving with two voltages such as 0 and a large voltage.

(Third embodiment)
A third embodiment of the present invention will be described with reference to FIG. FIG. 6B is a top view of the liquid lens in the third embodiment. The third embodiment has a structure in which the ring-shaped EW drive pump section as described in the second embodiment is further divided into small triangular prism-shaped EW drive pump sections. As shown in FIG. 6B, a large number of electrically independent substantially triangular prism-shaped EW drive pump units 902 are arranged so as to surround the optically effective unit 901. In FIG. 6B, 48 EW drive pump units 902 are arranged side by side, but the number is not limited to this number. Specifically, in the configuration of FIG. 6 (b), there is a pair of electrodes insulated from each other on each hypotenuse of each triangular prism (noting one triangular prism, the two electrodes on the two hypotenuses are electrically connected to each other. The electrodes of each triangular prism are controlled independently. In other words, in this embodiment, the drive pump unit has a triangular prism shape whose interface is triangular, and the triangular pump drive pump unit has a triangular prism in which a holding unit is disposed around the optically effective portion. Are arranged so as to alternately come to the opposite surface.

A large voltage V1 is applied to each EW drive pump unit 902. Since the EW drive pump unit 902 is small, the amount of liquid that can be sent is very small. For this reason, a minute change in optical power can be achieved while applying a high voltage V1. In addition, the EW drive pump unit 902 can respond at high speed. Furthermore, since the number of EW drive pump units 902 is large, it is possible to give a large change in optical power substantially continuously by controlling the number of operations of the EW drive pump units 902. FIG. 7 illustrates this.

FIG. 8 is a schematic view showing the operation of one subdivided triangular prism-shaped EW drive pump unit 902 taken out. Similar to the EW drive pump unit of the first embodiment, the EW drive pump unit 902 includes two liquids 1101 and 1102, a liquid interface 1103, an electrode 1104, an insulating film 1105, and a protrusion 1106. For simplicity, FIG. 8 is a view that penetrates the front surface of the EW drive pump portion that forms a triangular prism, but this surface is originally insulated from the electrode 1104 of the adjacent EW drive pump portion as in the back surface. A membrane 1105 is disposed. Here, a voltage V 1 is applied between the conductive liquid 1101 and the electrode 1104. Then, the contact angle between the liquid interface 1103 and the insulating film 1105 changes, and the position of the vertex 1107 of the triangle formed by the liquid interface 1103 moves (see FIG. 8B). As a result, the liquid 1102 is pushed by the liquid interface 1103, and a liquid flow is generated as shown by the arrows. When the liquid flow pushes a liquid interface (not shown) in the optical effective unit 901, the shape of the liquid interface changes as in the first and second embodiments, and the optical power changes.

6 (b) and the structure of FIG. 4 of the second embodiment may be combined so that the EW drive pump unit 902 has a multilayer structure as shown in FIG. 9 (a). In addition, as shown in FIG. 9B, when a plurality of EW drive pump units are driven at the same time or when they are driven in large numbers, the drive pump is in a point-symmetrical position with respect to the center (optical axis) of the optical effective unit 1301 It is desirable to operate the part. In this case, the EW drive pump unit always drives at least two at the same time. For example, when operating three drive pump units, as shown in FIG. 9 (c), the EW drive pump unit at a position symmetrical about 120 degrees about the optical axis is driven. By driving in this way, the liquid flow by each EW drive pump unit is not hindered, and a uniform flow is generated in the optical effective unit 1301, and the liquid interface of the optical effective unit 1301 is changed from the spherical surface. Can be suppressed.

As described above, by arranging a large number of EW drive pump units having a small liquid flow rate, it is possible to give a substantially continuous optical power change. Furthermore, by driving the EW drive pump unit that is point-symmetric about the optical axis, it is possible to change the liquid interface shape as a spherical surface. The liquid lenses in the first to third embodiments so far are liquid lenses that increase the optical power when the EW drive pump unit is driven by voltage application. However, the present invention is not limited to this, and by appropriately selecting the refractive index of the two liquids and the curvature of the interface, it is possible to configure a liquid lens in which the optical power decreases with voltage application. In the second and third embodiments, the size of each EW drive pump unit is varied, and the EW drive pump unit to be moved is appropriately selected according to the required liquid drive amount. You can take it.

(Fourth embodiment)
A fourth embodiment of the present invention will be described with reference to FIG. The fourth embodiment is an example in which a liquid lens which is a liquid optical element of the present invention is applied to a digital video camera. The liquid lens used here is assumed to be the liquid lens of the third embodiment.

In the digital video camera of this embodiment, the contrast of the image is detected when the image is focused, and the position with the highest contrast is detected as the focus position while shifting the focus. At this time, if the focus is greatly deviated, it takes time to detect the focus position. For this reason, a driving called wobbling is performed in which the focus is always moved small and the focus position is detected. In wobbling, the focus is moved back and forth on the image sensor with a width equal to or smaller than the depth of field, and the focus is moved toward the higher contrast. As a wobbling method, a method of minutely moving a lens or an image sensor is conceivable. However, in this method, moving means such as a motor or sound generated by them may enter a moving image. On the other hand, the liquid lens using the EW drive pump unit can be used very effectively as a wobbling element for moving the focus minutely because there is no movable part.

FIG. 10A shows a configuration diagram when a liquid lens is used as the wobbling element. An image 1408 of the subject 1402 on the image sensor 1401 is converted into an electrical signal by the image sensor 1401 and sent to the image processing circuit 1403. The image processing circuit 1403 detects the contrast of the obtained image and determines whether the subject 1402 is in front or behind. At this time, when the subject image 1408 is blurred, the contrast of the subject image 1408 is low. Therefore, as shown in FIG. 10B, the timing of capturing an image with the image sensor 1401 is synchronized with the timing of the minute focus fluctuation of the liquid lens 1407 of the present invention. Accordingly, the contrast of the subject before and after the current focus position 1501 can be detected as shown in FIG. At this time, for example, when the best focus position of the subject image 1408 is 1502, the contrast of the image increases as the focus is moved in the direction of 1502. Therefore, it is possible to grasp the focus direction of the subject image 1408 by minutely changing the optical power of the liquid lens 1407 and measuring the contrast of the image before and after the current focus position.

Here, the depth of field changes depending on the F value of the optical system that forms an image of light from the subject. That is, when the subject is bright, the aperture is narrowed down, so that the depth of field becomes deep. For this reason, in order to grasp the direction of focus, it is necessary to increase the amount of focus movement in wobbling. Therefore, the F value of the aperture 1405 of the imaging optical system 1404 is detected, and information on the F value is sent to the liquid lens driving circuit 1406. The liquid lens 1407 changes the fluctuation amount of the optical power in accordance with the signal from the drive circuit 1406. Thereby, the blur amount of the image on the image sensor 1401 is increased or decreased. The fluctuation amount of the optical power is proportional to the F value of the diaphragm 1405. The fluctuation amount is small when the diaphragm is open (dark place), and the fluctuation amount is large when the diaphragm is narrowed (bright place). That is, when the subject is dark, a small number of EW drive pump units 902 in FIG. 9 are driven, and when the subject is bright, a large number of EW drive pump units 902 are driven. At this time, the wobbling frequency is driven at half the video frame rate. This is because the focus position is moved back and forth in two frames. That is, when shooting a moving image at 60 fps, the drive frequency of the liquid lens 1407 is 30 Hz. In order to drive at such a high frequency, the configuration of the liquid lens of the present invention that can apply a high voltage to the EW drive pump unit is desirable.

(5th Example)
The fifth embodiment of the present invention will be described with reference to FIG. The fifth embodiment is an example in which a liquid lens which is a liquid optical element of the present invention is applied to a digital still camera. FIG. 11A is a schematic diagram showing the external appearance of a digital camera to which a liquid lens is applied. 1601 is a photographing lens, 1602 is a finder, 1603 is a flash light emitting unit, and 1604 is a shutter switch.

FIG. 11B is a block diagram of the main part of the digital camera of FIG. In the digital camera of FIG. 11B, the liquid lens 1702 of the present invention is combined with the solid lens 1701 and used as a unit, and light passing through the optical system of the solid lens 1701 and the liquid lens 1702 is used as an aperture 1703 and a shutter 1704. Then, an image is formed on the image sensor 1705. The liquid lens 1702, the diaphragm 1703, and the shutter 1704 are controlled by a control signal from the camera control unit 1706. The other elements in FIG. 11 (b) are common in digital cameras, but will be described briefly below. A signal processing unit 1707 performs analog signal processing, and an A / D converter 1708 converts the analog signal to digital. An image memory 1709 is a memory for storing digital signals, and an image processing unit 1710 performs signal conversion, signal correction, and the like. The main CPU 1711 controls all operations of the digital camera. The CPU 1711 controls the image processing unit 1710, the camera control unit 1706, and the like by executing a control program stored in the ROM 1712. Reference numeral 1713 denotes a RAM that provides a work area for program execution, and reference numeral 1714 denotes an image memory that stores captured images to be displayed on the pixel display unit 1715. The compression / decompression processing unit 1716 encodes image information in the image memory 1709, and the encoded data is stored in the memory card 1718 via the I / F 1717. The camera control unit 1706 executes various operations based on operation signals from the operation switch 1719.

When the shutter switch 1604 is pressed, the camera control unit 1706 sends a signal to the dimming control unit 1720 to perform a predetermined operation such as causing the flash 1603 to emit light. At this time, the liquid lens 1702 disposed in the photographing lens 1601 controls the focus position by changing the optical power so as to tie an image by the imaging lens 1601 on the imaging element 1705 in accordance with a signal from the main CPU 1711. Reference numeral 1721 denotes a communication circuit which is used when a photographed image is transmitted to the outside wirelessly. In this manner, by applying the liquid lens capable of high-speed response of the present invention to so-called autofocus, it becomes possible to realize high-speed autofocus.

(Sixth embodiment)
A sixth embodiment in which the liquid lens which is the optical element of the present invention is applied to a photographing lens of a camera-equipped mobile phone will be described. FIG. 12 is a schematic diagram showing a main part of a mobile phone using the liquid lens of the present invention. The camera-equipped mobile phone shown in FIG. 12 includes the liquid lens 1803 of the present invention as at least a part of the photographing lens unit 1802 of the camera unit 1801, and is configured so that the image is focused on an image sensor 1804 such as a CCD. ing. Since the liquid lens of the present invention is expected to respond at high speed, it is highly effective as an autofocus element for a camera.

The other elements in FIG. 12 are typical for camera-equipped mobile phones, but will be described briefly below. Reference numeral 1805 denotes a mobile phone control unit, which includes a CPU 1806 and a ROM 1807. Reference numeral 1808 denotes an antenna, and 1809 denotes a wireless unit, which are connected to the control unit 1805. Reference numeral 1810 denotes a microphone, 1811 denotes a receiver, and 1812 denotes an image storage unit. Images captured by the camera 1801 are stored in the image storage unit 1812. Reference numeral 1813 denotes an operation key, 1814 denotes a display unit such as an LCD, and 1815 denotes a shutter key for camera photography.

(Seventh embodiment)
A seventh embodiment of the present invention will be described with reference to FIG. The seventh embodiment is an example in which the liquid lens of the present invention is applied to a surveillance camera. FIG. 13A is a schematic diagram showing the appearance of a surveillance camera using the liquid lens of the present invention, and FIG. 13B is a block circuit diagram of the surveillance camera system. In FIG. 13A, reference numeral 1901 denotes a lens unit, 1902 denotes a pan head unit, and 1903 denotes a cover that covers the lens unit.

In FIG. 13B, the feature of this embodiment is that a liquid lens 1904 which is an optical element of the present invention is incorporated as one of the lenses constituting the lens unit 1901. In FIG. 13B, a solid lens group 1905, a liquid lens 1904, and an image sensor 1906 are arranged along the optical axis, and the output of the image sensor is an image processing circuit 1908 and a focus processing circuit via an amplifier 1907. 1909, respectively. The pan head unit 1902 is provided with a pan direction drive motor 1910 and a tilt direction drive motor 1911 for driving the lens unit 1901. The output of the video processing circuit 1908 is connected to the network processing circuit 1913 in the pan head unit, and the output of the focus processing circuit 1909 is connected to the CPU 1912. The output of the CPU 1912 is connected to an external LAN 1914 via a network processing circuit 1913, and a personal computer 1915 is connected to the LAN 1914. Further, the output of the CPU 1912 is connected to drive motors 1910 and 1911 via a pan drive circuit 1916 and a tilt drive circuit 1917 to supply drive signals thereto. Further, the CPU 1912 is connected to the liquid lens driving circuit 1918. The liquid lens 1904 is driven by a liquid lens driving circuit 1918 to adjust the focus. Since the liquid lens of the present invention can respond at high speed, the surveillance camera of this embodiment can increase the speed of focus.

101, 102 ... Liquid (conductive liquid, non-conductive liquid), 103a ... Interface of optical effective part, 103b, 103c, 103d ... Interface of drive pump part, 104a, 104b, 104c ...・ Electrodes, 105... Insulating film, 106a, 106b, 106c... Projection of driving pump part (holding part at interface end), 108a, 108b, 108c.

Claims (12)

It has an optically effective part and a plurality of drive pump parts responsible for changing the optical characteristics
Each of the drive pump units includes a holding unit that holds an end portion of an interface formed by a conductive liquid and a non-conductive liquid that are immiscible with each other, and the conductive pump unit is disposed with respect to the holding unit. An electrode insulated from the liquid, and by controlling a voltage applied to the electrode, the end portion of the interface contacting the electrode is displaced by an electrowetting phenomenon, and the holding portion and By moving the conductive and non-conductive liquid sandwiched between the electrodes, at least two kinds of non-mixed liquids including the conductive and non-conductive liquid existing in communication with the drive pump units are provided. A liquid optical element capable of changing an optical characteristic by changing a state of the optically effective portion where the liquid exists,
The voltage applied to the electrodes of each of the drive pump units is at least two discrete voltage values within the operating range, and the voltages applied to the electrodes of the plurality of drive pump units are controlled independently of each other. A liquid optical element characterized by changing a state of an interface in an effective portion. The liquid optical element according to claim 1, wherein one of the at least two voltages is 0V. The liquid optical element according to claim 1, wherein the plurality of drive pump units are arranged point-symmetrically with respect to an optical axis of a liquid lens configured by an interface of the optical effective unit. 4. The liquid optical according to claim 3, wherein when a plurality of the driving pump units are driven, the driving pump unit at a point-symmetrical position about the optical axis is selected and driven. element. The drive pump unit has a triangular prism shape whose interface shape is triangular,
4. The triangular prism-shaped drive pump section is disposed around the optically effective section so that one surface of the triangular prism on which the holding section is disposed alternately and alternately comes to a facing surface. Or 5. The liquid optical element according to 4. The plurality of drive pump units are arranged in multiple layers around the optical effective unit around an optical axis of a liquid lens formed by an interface of the optical effective unit. Liquid optical element. A lens comprising the liquid optical element according to claim 1 configured as a liquid lens and a solid lens as a unit. A camera comprising the liquid optical element according to claim 1 configured as a liquid lens as at least part of an optical system for imaging light from a subject. The camera according to claim 8, wherein the camera is a digital camera or a surveillance camera. Having a camera part,
The liquid optical element according to any one of claims 1 to 6 configured as a liquid lens is mounted as at least a part of an optical system that forms an image of light from a subject in the camera unit. Camera phone. An optically effective portion having a function of changing optical characteristics, and a plurality of drive pump portions, each of the drive pump portions having an end portion of an interface formed by an electrically immiscible conductive liquid and a nonconductive liquid. A holding portion that holds the electrode and an electrode that is disposed with respect to the holding portion and insulated from the conductive and non-conductive liquids, and controls the voltage applied to the electrode to control the electrowetting. Due to the ting phenomenon, the end of the interface in contact with the electrode is displaced, and the conductive and non-conductive liquid sandwiched between the holding part and the electrode is moved to communicate with each drive pump part. A method of controlling a liquid optical element capable of changing an optical characteristic by changing a state of the optically effective portion in which at least two kinds of non-mixed liquids including the conductive and non-conductive liquids are present. I,
A method of controlling a liquid optical element, wherein the voltage applied to the electrodes of the plurality of drive pump units is selected from at least two discrete voltage values within the operating range and controlled independently. 12. The liquid optical element according to claim 11, wherein when driving a plurality of the driving pump units, the driving pump unit at a point-symmetrical position about the optical axis is selected and driven. Control method.

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