WO2020111669A1 - Device for cleaning surface by using electrowetting element and method for controlling same - Google Patents

Abstract

The present application provides a device for effectively removing alien substances from the surface of an object and a method for controlling same. The present application may provide an object surface cleaning device comprising: a substrate provided on the surface of a predetermined object; an electrode provided on the substrate and comprising first and second electrodes disposed in different planes, respectively; a dielectric layer provided on the substrate and configured to cover the electrode; and a control device configured to supply AC power to the electrode. The control device may be configured to provide the electrode with first AC power having a predetermined first frequency and a predetermined first voltage for one hour, in order to cause droplets on the surface of the object to vibrate by means of a periodic change in electrostatic force produced by the electrode. The first frequency may be configured as the resonant frequency of the droplets.

Description

Surface cleaning device using electrowetting element and control method therefor

The present application relates to an electrowetting device, and more particularly, to an apparatus configured to clean the surface of an object using the electrowetting device.

In general, when an electric field is applied to a liquid placed in a solid phase, especially a droplet, the contact angle and surface tension of the fluid to the solid change. This behavior is defined as the electrowetting effect or phenomenon. Liquid droplets, i.e., liquid droplets, can be moved using a change in the contact angle and contact area according to the electrowetting effect, and the direction of movement of the droplets can also be controlled by controlling the direction of the applied electric field. Accordingly, an electrowetting element that is configured to generate an electrowetting effect has been developed, and has been applied to various fields.

More specifically, electrowetting devices have been applied in biotechnology to move, combine, and divide various liquid biomaterials including blood for the purpose of experimentation and analysis. In addition, electrowetting devices have been applied to the development of new types of displays. Since such an electrowetting device has the ability to manipulate fine droplets even with a relatively simple structure, it can be applied to fields different from the aforementioned fields.

An object of the present application is to provide an apparatus configured to clean the surface of an object using an electrowetting effect.

In order to achieve the above object, the present application provides a substrate provided on the surface of a predetermined object; An electrode provided on the substrate and including first and second electrodes respectively disposed in different planes; An insulating layer provided on the substrate and configured to cover the electrode; And a control device configured to supply AC power to the electrode, the control device having a predetermined first frequency to generate vibrations on the droplets on the object surface by periodic changes in the electrostatic force generated by the electrodes. And a first alternating current power source having a predetermined first voltage, provided to the electrode for a first time, and wherein the first frequency is set to a resonant frequency of the droplet.

The control device may be configured to detect the resonance frequency of the droplet while providing AC power to the electrode before supplying the first AC power. More specifically, while detecting the resonance frequency, the control device sequentially sweeps frequencies in a predetermined range of the provided AC power; Sensing the resonance of the droplet during the sweep; It may be configured to set the frequency at which the resonance occurs to the first frequency.

More specifically, while sweeping the frequencies in the predetermined range, the control device may be configured to gradually increase the frequency of the AC power source, starting from a predetermined frequency and until resonance occurs in the droplet. For example, the control device can be configured to sweep frequencies of 10 Hz-150 Hz.

Further, in order to sense the resonance of the droplet, the control device: acquires an image of the droplet using a sensor; It may be configured to analyze the acquired image to detect a sharp increase in the vibration of the droplet. If the resonance of the droplet is detected at a plurality of frequencies, the control device may be configured to set the highest frequency of the frequencies as the first frequency of the AC power. For example, the first frequency may be 30 Hz or 100 Hz, and the first voltage may have a range of 50V-150V.

Meanwhile, the control device may be configured to provide a second AC power having a second voltage greater than the first voltage to the electrode for a second time after providing the first AC power during the first time. . For example, the second voltage may have a range of 150V-200V.

More specifically, in order to supply the second AC power, the control device may be configured to increase the first voltage of the first AC power having the first frequency to the second voltage. Further, while providing the second AC power, the control device: reduces the second voltage to a third voltage smaller than the second voltage; It may be further configured to repeat the increase from the third voltage to the second voltage and the decrease from the second voltage to the third voltage. Also, the first time and the second time may be set at a ratio of 8:2.

Meanwhile, the first electrode may be disposed on the substrate, and the second electrode may be disposed above the first electrode. The first electrode is spaced apart from each other at a predetermined interval, and includes a plurality of first sub-electrodes disposed within the same plane, and the second electrode is spaced apart from each other at a predetermined distance, and a plurality of second sub-electrodes disposed within the same plane It may include. More specifically, the first and second sub-electrodes may be alternately arranged.

In addition, the electrode may include a predetermined first gap formed between the side of the first sub-electrode and the side of the second sub-electrode adjacent thereto, and the first gap may be 5 μm. Further, the electrode may include a second gap formed in a vertical direction between the first electrode and the second electrode, and the second gap may be set to be the same as the first gap.

The insulating layer includes: a first insulating layer disposed on the substrate and configured to cover the first electrode; And a second insulating layer disposed on the first insulating layer and configured to cover the second electrode.

While providing the first AC power, the control device may be configured to alternately supply the first AC power to the first and second electrodes.

The surface cleaning apparatus and control method according to the present application may generate resonance in droplets on the object surface by controlling the frequency of the AC power supplied. That is, the surface cleaning device and the control method may be configured to detect a resonance frequency and supply AC power having the detected resonance frequency. Thus, the droplets can be removed by moving quickly and smoothly out of the object surface while resonating.

In addition, the surface cleaning apparatus and control method according to the present application can also excite fine droplets on the object surface by additionally controlling the voltage of the supplied AC power. That is, the surface cleaning apparatus and the control method can expand the range of electrodes generated to excite fine droplets by increasing the voltage of the supplied AC power. Thus, microdroplets can also be properly excited and vibrated and removed from the object surface.

Therefore, the surface cleaning device and control method according to the present application can effectively vibrate and quickly and efficiently remove all droplets on the object surface by optimally controlling the frequency and voltage of the supplied AC power.

1 is a schematic view showing a surface cleaning apparatus using an electrowetting device according to the present application.

2 is a plan view showing the structure of an electrode in an electrowetting device.

3 is a perspective view showing a surface cleaning device applied to an imaging device.

4 is a flowchart showing a method of controlling a surface cleaning device using an electrowetting device according to the present application.

5 is a flowchart illustrating in detail the step of detecting the resonance frequency in the control method of the present application.

6 is a flowchart illustrating in detail the steps of providing a second AC power having a different voltage from the voltage of the first AC power in the control method of the present application.

7 is a graph showing the behavior of droplets when AC power is supplied to the electrowetting device.

8 is a schematic diagram showing the behavior of droplets when AC power having different frequencies is supplied, respectively.

9 is a plan view showing droplets removed by a control method according to the present application.

10 is a schematic diagram showing the correlation between the range of an electric field and the size of droplets that can be excite.

11 is a schematic diagram showing fine droplets excited by an extended electric field due to increased voltage.

12 is an exploded perspective view showing a modified example of an electrowetting device in the surface cleaning apparatus according to the present application.

13 is a schematic view showing a surface cleaning device using a modified example of an electrowetting device.

14 is a plan view showing an electrode in a modified example of the electrowetting device.

15 is a plan view showing a modified example of an electrode in a modified example of the electrowetting element.

16 is a schematic diagram showing a correlation between the range of an electric field and the size of droplets that can be excite in a modified example of the electrowetting device.

17 is a schematic diagram showing fine droplets excited by an extended electric field due to an increased voltage in a modification of the electrowetting device.

18 is a flowchart illustrating in detail the steps of providing a first AC power source having a resonance frequency and a first voltage in a control method of the present application.

Embodiments of the surface cleaning apparatus and the control method according to the present application will be described in detail below with reference to the accompanying drawings.

In the description of the embodiments, the same or similar elements are assigned the same reference numbers regardless of the reference numerals, and redundant descriptions thereof will be omitted. The suffixes "modules" and "parts" for components used in the following description are given or mixed only considering the ease of writing the specification, and do not have meanings or roles distinguished from each other in themselves. In addition, in describing the embodiments disclosed in this specification, detailed descriptions of related known technologies are omitted when it is determined that the gist of the embodiments disclosed in this specification may be obscured. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical spirit disclosed in the specification is not limited by the accompanying drawings, and all modifications included in the spirit and technical scope of the present application , It should be understood to include equivalents or substitutes.

Terms including ordinal numbers such as first and second may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from other components.

When an element is said to be "connected" or "connected" to another component, it is understood that other components may be directly connected to or connected to the other component, but there may be other components in between. It should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that no other component exists in the middle.

Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present application, the terms "comprise", "comprises" or "have" are intended to indicate that there are features, numbers, steps, actions, components, parts or combinations thereof described in the specification. It should be understood that the existence or addition possibilities of one or more other features or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance. In addition, for the same reason, this application does not depart from the disclosed technical purposes and effects, and some features, numbers, steps, even from combinations of related features, numbers, steps, actions, components, parts described using the terms mentioned above. It should also be understood that combinations of omissions, operations, components, and parts are also included.

Embodiments described herein relate to apparatus and methods for cleaning the surface of an object. However, it will be readily apparent to those skilled in the art that the principles and configurations of the described embodiments can be equally applied to devices having different purposes and uses than surface cleaning without modification.

1 is a schematic view showing a surface cleaning apparatus using an electrowetting device according to the present application, and FIG. 2 is a plan view showing the structure of an electrode in the electrowetting device of FIG. 1. In addition, Figure 3 is a perspective view showing a surface cleaning device applied to the imaging device. With reference to these drawings, a surface cleaning apparatus using an electrowetting element according to the present application is described below.

The surface cleaning apparatus of the present application may be configured to clean the surface of the object (O) by removing liquid droplets (D) existing on the surface of the object (O). The droplet D on the object O can be moved on the surface of the object O to be removed, and the electrowetting effect can be applied as described above for the movement of the droplet D. Accordingly, the surface cleaning apparatus of the present application may include the electrowetting element 100 that is basically configured to generate movement of the droplet D. In FIG. 1, the electrowetting element 100 is shown in a cross-section differently from other components in order to better show its internal structure. When considering the modification (modification, modified example, or modified embodiment) of the electrowetting device 100 of FIGS. 12 to 15 to be described later, the electrowetting device 100 of FIGS. 1 and 2 is a basic example or basic embodiment).

Referring to FIG. 1, the electrowetting device 100 may include a substrate 110. The substrate 110 may be disposed on the surface of the object O to be cleaned. The electrowetting device 100 may also include an electrode 120 provided on the substrate 110. More specifically, the electrode 120 may be disposed on the surface of the substrate 110. The electrode 120 may be configured to form an electric field of a predetermined size by receiving power/power or voltage. As illustrated, a plurality of electrodes 120 may be disposed spaced apart from each other at a predetermined distance over the entire surface of the substrate 110. Accordingly, the electrodes 120 may uniformly form an electric field on the entire surface of the electrowetting device 100 and, further, the object O to be cleaned. The arrangement of the electrode 120 may be achieved in various ways, and as an example, the pattern of FIG. 2 may be applied to the electrowetting device 100. Referring to FIG. 2, the electrode 120 may include common electrodes 120a and 120c disposed to face each other. Also, a plurality of sub-electrodes 120b and 120d may be extended from the common electrodes 120a and 120c. These sub-electrodes 120b and 120d may be alternately arranged while being spaced apart from each other at predetermined intervals. In addition, as shown in the cross section of the electrowetting device 100 of FIG. 1, these sub-electrodes 120b and 120d may be arranged side by side in the same plane or layer on the substrate 100. . Accordingly, according to this pattern, the sub-electrodes 120b and 120d may form a uniform electric field across the electrowetting device 100. In practice, the electrode 120 shown in FIGS. 1 and other drawings in relation to the basic example of the electrowetting device 100 corresponds to the sub-electrodes 120b and 120d of FIG. 2. The electrode 120 may be made of various materials, for example, may be made of indium tin oxide (ITO).

The electrowetting device 100 may generate the intended electrowetting effect, that is, the motion of the droplet D, even with the substrate 110 and the electrode 120 alone. However, when the droplet D is in direct contact with the electrode 120, the droplet D may be electrolyzed before being moved under a relatively high power or voltage. Accordingly, the electrowetting device 100 may include an insulating layer 130 configured to cover the electrode 120. The insulating layer 130 is disposed on the substrate 110 and the electrode 120 in more detail, and covers not only the electrode 120 but also the surface of the substrate 110 exposed between the electrodes 120. Can be configured. That is, the electrodes 120 may be isolated from the outside by being exposed by the insulating layer 130. Therefore, due to the interposition of the insulating layer 130, the droplet D may not be electrolyzed by the electrode 120, but may be exposed only to the electric field generated by the electrode 120. The insulating layer 130 may be made of various materials, for example, made of silicon nitride. In addition, the electrowetting device 100 may further include a hydrophobic layer 140 provided on the insulating layer 130. More specifically, the hydrophobic layer 140 may be disposed over the entire surface of the insulating layer 130. The hydrophobic layer 140 may help the droplet D to move smoothly due to its repel property.

In such an electrowetting device 100, when an electric field is generated by applying power or voltage to any one electrode 120 disposed adjacent to the droplet D, the contact angle of the droplet D is changed by the electric field. Can be. More specifically, under the influence of the electric field, the droplet D is pulled toward the surface of the electrode 120, that is, the device 100, and the contact angle of the droplet D with respect to the surface can be reduced. Therefore, the droplet D can be moved toward the portion where the contact angle is reduced. Using this principle, the droplet D may be maneuvered to move in a desired direction by selectively applying power or voltage to a portion of the electrode 120, that is, the sub-electrodes 120b and 120d. . That is, by controlling the power supply to the electrode 120, the movement of the droplet D can be controlled. On the other hand, if an AC power or an AC voltage is applied to the electrode 120, the electric field and the electrostatic force applied thereto may also periodically fluctuate according to a frequency that alternates periodically. do. The droplet D may be excited by the variable electrostatic force, and may vibrate as illustrated in FIG. 7 to be described later. More specifically, the droplet (D) is the energy obtained by the excitation, as shown in FIG. 1, while vibrating on the surfaces of the electrowetting device 100 and the object O, it can move itself out of the surface. , As a result, can be removed from the surface. The random movement of the droplet D using the excitation and vibration effectively removes the droplet D while powering the electrode 120 as in the maneuvering of the droplet D described above. No detailed control of supply is required. Also, for the same reason, by using an excitation by the electrode 120, when AC power or voltage is simultaneously applied to the electrode 120, that is, all the sub-electrodes 120b and 120d, the object O is present on the surface. All droplets D to be vibrated and moved at the same time. Since the removal of the droplet D requires not merely elaborate manipulation of the droplet D, but merely the movement of the predetermined object O to the outside of the surface, the excitation and vibration of the droplet D described above is necessary for the removal of the droplet D. It can be more efficient and effective. Therefore, the surface cleaning device of the present application, in particular, the electrowetting element 100 may be configured to generate vibrations in the droplet D.

The basic example of the electrowetting device 100 shown in FIGS. 1 and 2 may be modified in various forms to more effectively and effectively remove the droplet D. One of these variations is shown in FIGS. 12-15 as an example. 12 is an exploded perspective view showing a modification of the electrowetting device in the surface cleaning device according to the present application, and FIG. 13 is a schematic view showing the surface cleaning device using the modification of the electrowetting device. 14 is a plan view showing an electrode in a modification of the electrowetting device, and FIG. 15 is a plan view showing a modification of the electrode in a modification of the electrowetting device. 13 shows a cross-section of a modification of the electrowetting device 100 obtained along line I-I in FIG. 12 in practice. With reference to these drawings, a modified example of the electrowetting element 100 is described in detail below.

In a modification of the electrowetting device 100, the electrode 120 is provided on the substrate 110, as shown in the previous basic example, and the first and second electrodes 121 and 122 separated from each other are shown. It can contain. The first and second electrodes 121 and 122 may be respectively disposed in different planes or layers. More specifically, the first electrode 121 may be disposed on the substrate 110 as an example, and the second electrode 122 may be disposed above the first electrode 121. have. The second electrode 122 may be spaced apart from the first electrode 121. That is, the second electrode 122 is at a predetermined distance from the first electrode 121 in the direction perpendicular to the substrate 110 (or the plane formed thereby) in the vertical direction in the electrowetting element 100, and precisely. Can be separated. By this separation, the first and second electrodes 121 and 122 may prevent electrical interference that may be caused by contact of the electrodes. Further, the spaced second electrode 122 may be oriented parallel to the substrate 110 or the first electrode 121 on the substrate 100. That is, the first and second electrodes 121 and 122 may be arranged or oriented parallel to each other. The parallel orientation is advantageous for the formation of uniform electric fields in which the first and second electrodes 121 and 122 cover the entire electrowetting element 100 and the object O. Due to such parallel orientation and separation, the first and second electrodes 121 and 122 can form a uniform electric field without basically interfering with each other.

More specifically, the first electrode 121 may include a plurality of first sub-electrodes 121a extending to a predetermined length. For example, each of the first sub-electrodes 121a may be formed of a narrow plate-like member elongated as shown, that is, a strip. The first sub-electrodes 121a are spaced apart from each other at predetermined intervals, and may be disposed in the same plane. Further, the first sub-electrodes 121a may be connected to each other by a single first common electrode 121b so that a predetermined power or voltage can be supplied at once. Similar to the first electrode 121, the second electrode 122 may also include a plurality of second sub-electrodes 122a extending to a predetermined length. For example, each of the second sub-electrodes 122a may also be formed of a narrow plate-shaped member that extends long, that is, a strip. The second sub-electrodes 122a may be spaced apart from each other at a predetermined distance, and may be disposed in the same plane, and may be connected to each other by a single second common electrode 122b for application of power or voltage. In addition, due to the arrangement and orientation of the aforementioned first and second electrodes 121 and 122, the first and second sub-electrodes 121a and 122a are also disposed in different planes or layers, respectively, and the first sub-electrode While the fields 121a are disposed on the substrate 110, the second sub-electrodes 122a may be disposed above the first sub-electrodes 121a. Furthermore, the second sub-electrodes 122a may be spaced apart from the first sub-electrodes 121a at a predetermined interval in a vertical direction, and the first and second sub-electrodes 121a and 122a are oriented parallel to each other. Can be.

In addition, as well illustrated in FIGS. 13 and 14, the first and second sub-electrodes 121a and 122a may be alternately disposed along the substrate 110. That is, any one of the second sub-electrodes 122a may be positioned between a pair of first sub-electrodes 121a adjacent to each other. On the other hand, any one of the first sub-electrodes 121a may be positioned between a pair of second sub-electrodes 122a adjacent to each other. By this alternating arrangement, the second sub-electrodes 122a may form an electric field of a predetermined size between the spaced first sub-electrodes 121a and their electric fields. On the other hand, the first sub-electrodes 121a may also form an electric field of a predetermined size between the spaced second sub-electrodes 122a and the electric fields by them. In general, when the sub-electrodes 121a and 122b are too close to each other in the horizontal direction in the same plane, electrical interference may occur between these electrodes 121a and 122b, and precisely, adjacent sides thereof. The electric field may not be generated effectively. However, as described above, the first and second sub-electrodes 121a and 122a are spaced apart from each other in the vertical direction, so that their side parts are configured to be as close as possible to each other in the horizontal direction without electrical interference. Can be. Accordingly, the first and second sub-electrodes 121a and 122a configured as described above are connected to each other and may form electric fields covering the entire surface of the object O. For this reason, as shown in FIG. 16 to be described later, the electric fields Fa and Fb formed to be connected to each other by the first and second electrodes 121 and 122 of the modified example of the electrowetting device 100 are of any size. The microdroplets (D2) can also be wrapped, so that the microdroplets (D2) can always be excited and vibrated to be removed.

In a more detailed configuration of the electrode 120, as shown in FIGS. 13 and 14, the first and second sub-electrodes 121a and 122a alternate with each other in different planes. Since it is disposed, a predetermined interval C1 may be formed in a horizontal direction between any one of the first sub-electrodes 121a and the second sub-electrodes 122a adjacent thereto. More precisely, the electrode 120 may include a first clearance C1 formed between the side of the first sub-electrode 121a and the side of the second sub-electrode 122a adjacent thereto. As described above, due to the arrangement in different planes, the first and second sub-electrodes 121a and 122a may be disposed as close as possible to each other, so the first distance C1 is also small in size, for example For example, it can be set to 5 μm. In addition, as illustrated in FIG. 13, since the first and second electrodes 121 and 122 are spaced apart from each other in the vertical direction, the electrode 120 is positioned in a vertical direction between the first and second electrodes 121 and 122. A second gap C2 formed accordingly may be included. The second interval C2 may be appropriately set to exclude electrical interference between the first and second electrodes 121 and 122, and accordingly, may be set equal to the first interval C1. Therefore, for example, the second interval C2 may be set to 5 μm in the same manner as the first interval C1. Since the first and second electrodes 121 and 122 include the first and second sub-electrodes 121a and 122a, the second gap C2 is between the first and second sub-electrodes 121a and 122b. It can also be described as the interval formed along the vertical direction. Further, referring to FIG. 14, each of the first and second sub-electrodes 121a and 122a may have a first width W1 and a second width W2, respectively. The widths W1 and W2 can be set equally for the formation of electric fields having a uniform distribution. For example, the first and second widths W1 and W2 may be set to 50 μm.

In this modification of the electrowetting device 100, the electrode 120 may be further modified to form more uniform electric fields. Referring to FIG. 15(a), the second sub-electrode 122a may be formed to have the same width in the third interval C3 between adjacent first sub-electrodes 121a. On the other hand, the first sub-electrode 121a may be formed to have the same width as an interval between adjacent second sub-electrodes 121a. Therefore, no gap may be formed in the horizontal direction between the first sub-electrode 121a and the second sub-electrode 122a. In addition, referring to FIG. 15(b), the second sub-electrode 122a may be formed to have a width greater than a third gap C3 between adjacent first sub-electrodes 121a. On the other hand, the first sub-electrode 121a may be formed to have a width greater than the distance between adjacent second sub-electrodes 122a. Accordingly, the second sub-electrode 122a may overlap the first sub-electrode 121a or the first sub-electrode 121a may overlap the second sub-electrode 122a. 15(a) and (b), electric fields generated in the first and second sub-electrodes 121a and 122a may be closer to each other or overlap with each other, and thus electrowetting. More uniform electric fields may be formed throughout the device 100 or the object O.

In addition, the insulating layer 130 may be configured to cover the electrode 120 according to the above-described modification, in order to prevent electrolysis of the droplet D and stable operation of the electrowetting device 100. In more detail, the insulating layer 130 may include a first insulating layer 131 disposed on the substrate 110 and configured to cover the first electrode 121. The first insulating layer 131 may be configured to cover not only the first electrode 121 but also the surface of the substrate 110 exposed between the first sub-electrodes 121a. In addition, the insulating layer 130 may be disposed on the first insulating layer 131 and may include a second insulating layer 132 configured to cover the second electrode 122. The second insulating layer 132 may be configured to cover the surface of the first insulating layer 131 exposed between the second electrode 122 as well as the second sub-electrodes 122a thereof, as shown. . As described above, in order to exclude electrical interference, the second gap C2 needs to be formed in the vertical direction between the first and second electrodes 121 and 122. Therefore, as illustrated, in order to secure the second gap C2, the first insulating layer 131 may be interposed between the first and second electrodes 121 and 122. In addition, the second electrode 122 may be disposed on the interposed first insulating layer 131. By the insulating layer 130, the electrode 120, that is, the first and second electrodes 121 and 122 may be isolated from being exposed to the outside, and stably for the movement and removal of the droplet D An electric field can be formed. In addition, since the insulating layer 130 is configured to cover the first and second electrodes 121 and 122 as a whole, it is formed to have a sufficient thickness, thereby ensuring sufficient electrical stability of the first and second electrodes 121 and 122. have.

On the other hand, in a modification of the electrowetting device 100, the substrate 110 and the hydrophobic layer 140 are the same as the substrate 110 and the hydrophobic layer 140 of its basic example described with reference to FIGS. 1 and 2, Therefore, additional description is omitted in the following. In addition, the characteristics of the electrode 120 and the insulating layer 130 of the basic example can be equally applied to the electrode 120 and the insulating layer 130 of the modified example, except that described above. Since the basic example and the modified example of the electrowetting element 100 are distinguished only in a detailed structure and share the same principle and concept, in the following description, the electrowetting element 100 is a basic example and modified example thereof unless otherwise specified. It can mean both. For the same reason, in the following description, the substrate 110, the electrode 120, the insulating layer 130, and the hydrophobic layer 140 may cover all the corresponding components of the basic example and the modified example, unless otherwise described.

In addition to the electrowetting device 100 according to the above-described basic example or modification, the surface cleaning device is configured to supply AC power to the electrowetting device 100 to generate a change in electrostatic force for excitation of the droplet D Power source 200 may be included. 1 and 13, the power supply 200 is connected to the electrowetting device 100, and to the electrode 120 thereof, and may apply AC power and AC voltage to the electrode 120. . In addition, in order to properly control the vibration of the droplet D, the behavior of the droplet D needs to be monitored. For example, when AC power is supplied to the electrode 120 by the power source 200, it is necessary to check whether or not vibration of the droplet D is actually generated. Accordingly, the surface cleaning device may include a sensing device 300 configured to detect the behavior of the droplet D during operation of the surface cleaning device. The behavior of the droplet D in the sensing device 300 can be recognized in various ways, for example, ultrasonic waves, infrared sensors, and the like can be applied to grasp the state of the droplet D. Of these various methods, directly acquiring an image of a droplet D may be advantageous in accurately determining its behavior. For this reason, the sensing device 300 may consist of an imaging device configured to acquire an image of the droplets D on the surface of the object O. Accordingly, the sensing device 300 may continuously acquire the images of the droplets D during operation of the surface cleaning device for precise and detailed control for the removal of the droplets D. The sensing device 300 may be disposed at any position capable of securing the entire image of the droplets D. As an example, FIGS. 1 and 13 show a sensing device 300 disposed above the object O such that the surface of the object O to be cleaned is entirely contained within a field of view (FOV). Furthermore, the surface cleaning device may include a control device 400 configured to control its operation. The control device 400 may be composed of a processor and related electronic components, and as shown, components of the surface cleaning device, that is, the electrowetting element 100, the power source 200, and the sensing device 300 and the electrical Can be connected to. Therefore, the control device 400 can control the entire surface cleaning device for the intended operation. As an example, the control device 400 may control the power source 200 to supply the required AC power or voltage to the electrowetting device 100. In addition, the control device 400 may monitor the behavior of the droplet D on the surface of the object O using the sensing device 300 in real time during operation of the surface cleaning device. More specific operation of the control device 300 will be described in more detail in the control method described below.

The surface cleaning device including the basic and modified examples of the wetting element 100 described above can be applied to various objects O and devices for cleaning. For example, the surface cleaning device may be applied to an imaging device, as shown in FIG. 3. The imaging device is generally configured to acquire an image using light incident through the lens. Therefore, when a foreign substance such as a droplet D exists in the lens, the foreign substance interferes with the incident light and thus an accurate image cannot be obtained. Particularly, when the imaging device is used outdoors, droplets (D) that obstruct the strokes of the correct image may be attached to the lens surface due to various causes including climatic factors such as snow, rain, and humidity. For this reason, the surface cleaning apparatus according to the present application may be installed in the camera 10 as an imaging device as an example, as shown in FIG. 3.

More specifically, the camera 10 includes a lens unit, and such a lens unit may be formed of a body 11 and a lens 12 installed in the body 11. Further, the camera 10 may include an image sensor 13 that acquires an image from light incident through the lens 12, and the image sensor 13 is, for example, a charged-coupled device (CCD). It can be done. The surface cleaning device, precisely the electrowetting element 100 (including the basic example and the modification example) may be installed on the surface of the lens 12 which is the object O to be cleaned. Further, the electrowetting device 100 may be integrally formed with the lens 12 (integrated as one body). That is, the electrowetting element 100 may be configured to have the same curvature as the surface to be in close contact with the surface of the lens 12. As such, the electrowetting element 100 forms one body with the lens 12 and may be regarded as the lens 12 itself as a single module or assembly. Furthermore, the electrowetting device 100 may be implanted or embedded in the body of the lens 12, and the device 100 may be integrally formed with the lens 12 even by such a device. Since the electric field is not affected by the intervening medium, such an embedded device 100 can still apply the electrostatic force due to the electric field to the surface of the lens 12, and accordingly the surface of the lens 12 surface It is possible to retain the ability to vibrate and remove the droplet D. In addition, the electrowetting element 100 applied to the lens 12 should not prevent light from entering. Therefore, the electrowetting device 100 may be configured to be transparent as a whole. In more detail, the substrate 110, the electrode 120, the insulating layer 130, and the hydrophobic layer 140 may be entirely made of a transparent material. The transparent electrowetting device 100 passes light incident to the lens 12 and simultaneously removes foreign matter such as droplets D. On the other hand, the camera 10 may include a separate cover installed on the body 11 to protect the lens 12, and instead of the lens 12, such a cover may be exposed outside the camera 10. . In this case, the electrowetting element 100 of the surface cleaning device may be attached to the lens cover to be integrated therewith. On the other hand, the lens cover itself may be made of an electrowetting element (100).

In addition, the internal power of the camera 10 may be used as the power source 200 of the surface cleaning device, and if necessary, a separate power source 200 may be connected to the electrowetting element 100 provided in the camera 10. Similarly, the control device of the camera 10 may be connected to the electrowetting element 100 to function as the control device 400. Furthermore, since the image sensor 13 of the camera 10 acquires an image through the lens 12, it is also possible to acquire an image of a foreign material, that is, a droplet D on the lens 12. Therefore, when the surface cleaning device is applied to the camera 10, the image sensor 13 may replace the sensing device 300.

In the surface cleaning device applied to the camera 10, as shown in FIG. 3(b), when a droplet D as a foreign material is generated on the lens 12 including the element 100, the control device AC power or voltage may be supplied to the device 100 by the 400, and the droplet D may be excited by the electrostatic force generated by the electrode 130. Subsequently, referring to FIG. 3(c), the droplet D may move out of the lens 12 while vibrating as indicated by the arrow, and the lens 12 is cleaned by the removal of such droplet D Can be. Therefore, the camera 10 can acquire an accurate and good image by cleaning the lens 12. When the camera 10 is used outdoors, since the droplet D can be frequently attached to the lens 12, the surface cleaning device is particularly effective in cleaning the lens 12 of the outdoor camera 10. Can be.

On the other hand, as described above, the surface cleaning device has the basic ability to clean the desired object surface by vibrating the droplet D, but the intended cleaning function can be maximized through more optimized control of the surface cleaning device. have. For this reason, an optimized control method for the surface cleaning apparatus according to FIGS. 1 to 3 and 12 to 15 has been devised and will be described with reference to additionally related drawings. 1 to 3, 12 to 15, and descriptions thereof are basically included and referenced in the following descriptions of control methods and drawings.

4 is a flow chart showing a method of controlling a surface cleaning device using an electrowetting device according to the present application, FIG. 5 is a flow chart showing in detail a step of detecting a resonance frequency in the control method of the present application, and FIG. 6 is a flow chart It is a flow chart showing in detail the step of providing a second AC power having a voltage different from the voltage of the first AC power in the control method of the application. 7 is a graph showing the behavior of droplets when AC power is supplied to the electrowetting device, and FIG. 8 is a schematic diagram showing the behavior of droplets when AC power having different frequencies is supplied.

The control methods described below control the operation of the components described above with reference to FIGS. 1-3 and 12-15, that is, various components, and may provide intended functions based on the operation. Therefore, the operations and functions related to the control method can be regarded as not only the characteristics of the control method, but also the characteristics of the relevant structural components. In particular, the control device 400, that is, the processor may be referred to by various names such as a controller and a control unit, and may control all components of the surface cleaning device to perform operations according to the control method. have. Accordingly, the control device 400 substantially controls all the methods and modes described in the present application, so that all steps to be described later can be characteristic of the control device 400. For this reason, although not described as being performed by the control device 400, the following steps and their detailed features can all be understood as features of the control device 400. In addition, in the following description of the control method, structural features and operations thereof are all referred to in FIGS. 1-3 and 12-15, and thus detailed descriptions thereof are omitted. In addition, in the description of the following control method, the features of the respective steps apply equally to both the basic example and the modified example of the electrowetting element 100, unless a specifically opposed disclosure is described. That is, both the basic and modified examples of the electrowetting element 100 and the surface cleaning apparatus including them can be basically driven by the features of the following steps.

The predetermined object O may be exposed to the external environment during use, and foreign substances such as droplets D may adhere to the surface of the object O due to various reasons. In practice, since the electrowetting element 100 of the surface cleaning device is disposed on the surface of the object O to be cleaned, the droplet D may be attached on the electrowetting element 100. However, as described above, since the electrowetting device 100 is integrated with the object O and functions as a part thereof, the droplet D on the surface of the electrowetting device 100 is an object O surface It can be considered as a droplet. In addition, as described above with reference to FIG. 3, the object O may actually correspond to a predetermined device 10 or a part thereof. In this case, the surface cleaning device (hereinafter simply referred to as "cleaning device"), that is, the control device 400 thereof, may first detect at least one droplet D, which is a foreign material disposed on the surface of the object O (S10) ). That is, the control device 400 may detect or determine whether a droplet D exists on the surface of the object O. The sensing step S10 may be performed by various methods, for example, attachment of the droplet D may be detected from an image acquired by the sensing device 300. In addition, when the droplet D is disposed on the surface of the object O, the resistance of the entire surface of the object O, that is, the electrowetting device 100 may also change due to the resistance of the droplet D itself. The change in resistance can result in a change in impedance in the electrowetting device 100, and more precisely the electrode 120. Accordingly, when a change in impedance is sensed, the control device 400 may detect and determine that the droplet D is attached to the surface of the object O. The detection of the droplet D based on the impedance can be performed using only the basic configuration of the electrowetting element 100 without an additional device, thereby simplifying the cleaning device and accurately detecting the droplet D.

On the other hand, as described above, when AC power or AC voltage is applied to the electrodes 120, the electrostatic force, which fluctuates periodically, may be applied to the droplet D due to periodic alteration of the frequency. have. Such an electrostatic force may excite the droplet D, and the droplet D may begin to vibrate due to the excitation. In addition, as shown in FIG. 7, as time passes, the vibration amount of the droplet D (in the drawing, the height of the deformed droplet D) may gradually increase, and the movement of the droplet D may increase. Sufficient vibration can be generated. In particular, if AC power is applied to the electrodes 120 at a frequency (hereinafter referred to as "resonant frequency") capable of generating resonance in the droplet D, the mechanical energy obtained by the droplet D due to the generated resonance is Maximized, and maximum vibration and movement can be generated in the droplet D. Therefore, the droplet D can move out of the surface of the object O more rapidly under the resonance frequency. For this reason, the control method of the present application can be configured to provide an AC power source having a resonance frequency for more efficient and effective removal of the droplet D.

For supply of the AC power, the control device 400 may be configured to detect the resonance frequency of the droplet D first (S20). That is, when the droplet D is detected through the sensing step S10, the control device 400 may perform a series of steps for detecting the resonance frequency of the droplet D immediately attached. In the detection step S20, the resonance frequency can be specified through various methods. However, the droplet D that is actually attached may have various sizes, and accordingly, the resonance frequency may be slightly changed by not only the size of the droplet D, but also various other factors. Therefore, in order to accurately specify the resonant frequency, the resonant frequency needs to be detected whenever the droplet D is detected. For this reason, during the detection step S20, the control device 400 may be configured to search the resonance frequency in real time while continuously supplying AC power to the electrowetting element 100.

For this search, referring to FIG. 5, in the detection step S20, the control device 400 may sequentially sweep frequencies in a predetermined range while supplying AC power to the element 100 (S21). . That is, in the detection step S20, the control device 400 may supply AC power having one different frequency at a time to the electrode 120 of the device 100 in order to find the resonance frequency. In other words, the control device 400 may change the frequency of the AC power supplied in stages while supplying AC power of a constant voltage. More specifically, in the sweep step (S21), the control device 400 may gradually increase the frequency of the AC power supplied starting from a predetermined frequency (S21a). This increasing step S21a may be continuously performed until resonance occurs in the droplet D. On the other hand, since the resonance of the droplet D can occur at multiple frequencies, even if the resonance of the droplet D occurs and is sensed, the frequency of the AC power may be continuously increased to detect an additional resonance frequency. have. On the other hand, it is inefficient to perform sweeps for all frequency bands, and thus the frequency ranges to be swept need to be limited. Among various factors, to limit the frequency range, the vibration behavior of the droplet D according to the frequency can be considered. First, as shown in FIG. 8(b), at a relatively low frequency, the droplet D may vibrate at a low cycle and show large deformation. However, a large displacement increases the contact surface and friction between the surface of the droplet D and the object O, as shown, which may be disadvantageous for smooth movement of the droplet D. On the other hand, referring to Figure 8 (a), at a relatively high frequency, the droplet can vibrate at a high period without significant deformation. Therefore, the contact surface between the droplet D and the surface of the object O is relatively reduced, and the frictional force can also be relatively reduced by the reduced contact surface. Under reduced friction, high periodic fluctuations can promote droplet D to start moving from its initial position. Therefore, vibration and resonance at a relatively high frequency may be advantageous for smooth movement and removal of the droplet D. For this reason, the sweeped frequency range can be set to start with a relatively low frequency, but include relatively high frequencies, for example, 10 Hz-150 Hz. In this case, in the increasing step (S21a ), the control device 400 may gradually increase the frequency of the AC power supplied from a predetermined frequency of 10 Hz to a relatively high frequency of 150 Hz.

In addition, referring to FIG. 5 again, during the sweep step (S22), the control device 400 may detect the resonance of the droplet D generated at a specific frequency (S22). In the sensing step (S22), the control device 400 may detect the resonance of the droplets using the sensing device 300, and various methods may be applied thereto, for example, ultrasonic waves, infrared sensors, and the like. . Among these various methods, a sensing device 300 made of an imaging device may be used to accurately determine the state of the droplet D, so that the resonance of the droplet D is obtained by the sensing device 300 It can be detected through. More specifically, as shown in FIG. 5, in the sensing step (S22 ), first, the control device 400 uses the sensor, that is, the sensing device 300 to perform the sweep of the frequency while the droplet D is performed. The image may be continuously acquired (S22a). As described above with reference to FIG. 2, when a cleaning device is applied to the camera 10, an image sensor 13 embedded in the camera 10 may be used to acquire an image of the droplet D. If resonance occurs in the droplet D, the vibration of the droplet D increases rapidly, and this increase can be clearly confirmed through an image. Accordingly, the control device 400 may analyze the acquired image and determine a sudden increase in vibration of the droplet D from the analyzed image (S22b). When the sudden increase in vibration is determined or sensed as described above, the control device 400 may detect that resonance is generated in the droplet D.

In the sensing step (S22), when a sudden increase in vibration, that is, resonance is detected, the control device 400 may set the frequency of the AC power supplied to the resonance frequency when such resonance is sensed (S23). In addition, the control device 400 may set the frequency at which the resonance is sensed in the sensing step S22 as the frequency of the AC power to be supplied to the electrowetting device 100 in the future. In most cases, a rapid increase in vibration occurs in a plurality of droplets D on the surface of the object O, so that detection of resonance and setting of the resonance frequency can be performed relatively easily. Nevertheless, for more consistent and objective detection of resonance and setting of the resonance frequency, the control device 400 may detect or determine that sudden vibration has occurred in at least one of the droplets D on the surface of the object O. At this time, it may be sensed or determined that resonance has occurred, and for this reason, the frequency at this time may be set as the resonance frequency.

As mentioned above, the resonance frequency of the droplets D may be slightly changed due to various factors. However, practically in most cases, the size of the attached droplets D is limited to a range of approximately 2-3 micrometers. Therefore, the resonance of the droplet D is also generally generated at 30 Hz. Also, the resonance of the droplet D is additionally generated at a higher frequency, 100 Hz. Therefore, in the setting step (S23), the control device 400 sets 30 Hz and 100 Hz as the first and second resonant frequencies, respectively, and any one of them is an AC power to be supplied to the electrowetting device 100. Can be set as frequency. Furthermore, as discussed above with respect to FIG. 8, the droplet D can be moved more smoothly and quickly by vibration and resonance at a relatively high frequency. Therefore, if a plurality of resonance frequencies are detected through the detection steps (S20: S21-S23 ), the control device 400 may select a higher frequency as the actually detected resonance frequency. That is, the control device 400 may set the highest frequency among the plurality of resonance frequencies to the frequency of the AC power to be supplied. For example, the control device 400 may set the second resonant frequency 100 Hz, which is relatively higher than the first resonant frequency 30 Hz, as the frequency of the AC power to be supplied, for effective removal of the droplet D.

Referring to FIG. 4 again, as discussed above, a single resonant frequency is sensed or one of a plurality of resonant frequencies sensed is selected through the detection step S20, and accordingly, a specific resonant frequency is an AC power source. Can be set for the supply of. In this case, the control device 400 may provide or supply the first AC power having the set resonance frequency, that is, the first frequency, to the electrowetting device 100 for vibration of the droplet D and removal thereof. (S30). In the supply step (S30), the first AC power supplied may have a predetermined first voltage. The first voltage may be appropriately set according to the characteristics of the first AC power source or a voltage required in a device equipped with a cleaning device, and may have, for example, a range of 50 V-150 V. In addition, for the same reason, the AC power may have the same first voltage even during the detection step S20 described above. In addition, the first AC power may be provided to the electrowetting device 100 for a predetermined first time period, and the first time is appropriately set to generate sufficient movement and removal of the droplet D. Can be. More specifically, the control device 400 may use the sensing device 300 to check the state of the droplet D on the surface of the object O, and the droplet D may be sufficiently removed from the surface. Until the supply of the first AC power can be continued.

By supplying an AC power having a resonance frequency detected during the supply step (S30), the droplets (D) can be removed from the surface of the object (O) while greatly vibrating, and this series of processes is well illustrated in FIG. 9. . 9 is a plan view showing droplets removed by a control method according to the present application, and the operation of the cleaning device applied to the camera 10 according to FIG. 3 is illustrated as an example. First, referring to FIG. 9(a), a plurality of droplets D may be attached as a foreign material to the surface of the lens 12 during use of the camera 10. In this case, the cleaning device, that is, the control device 400 may detect the presence of the droplets D through the sensing step S10. Subsequently, the control device 400 may detect the resonance frequency by performing the detection step S20 and supply the first AC power having the detected resonance frequency to the electrowetting device 100. Due to this first AC power, as shown in FIG. 9(b), resonance occurs in the droplets D on the surface of the lens 12, and the droplets D may be excited by maximum energy. have. As shown, the droplets D can quickly move out of the surface of the lens 12, as shown by the arrows by the energy obtained while vibrating greatly by resonance. In addition, since the droplets D are greatly vibrated by the generated resonance, the droplets D adjacent to each other may be combined with each other to form a droplet D of an increased size. Furthermore, the droplet D of an increased size may have a larger size while absorbing other droplets D as it moves. The large droplet D generated by the resonance may vibrate larger due to the increased size and mass, and thus can move more quickly and smoothly out of the surface of the lens 12, that is, a certain object O. . Accordingly, the supply of the AC power having the resonant frequency may not only amplify the vibration of the droplet D, but also may have an effect of promoting the movement of the droplet D as described above. As a result, the droplet D can be removed from the surface by moving out of the surface of the lens 12, that is, the object O, so that the surface can be cleaned.

On the other hand, as shown in Figure 9 (c), most of the droplets D1 are moved and removed by the supply of the first AC power, but relatively small or fine droplets D2 (hereinafter, "fine liquid") The enemy") is the object (O). That is, it may remain on the surface of the lens 12. This phenomenon can be explained by a limitation on the size of the droplet D that can be affected by the electric field generated by the electrode 120. In this regard, FIG. 10 is a schematic diagram showing the correlation between the range of an electric field and the size of droplets that can be excite. 10 shows, for example, a basic example of the electrowetting element 100 described above. 10, adjacent electrodes 120 are spaced apart from each other by a predetermined distance. In addition, since the intensity or range of the electric field is determined according to the voltage supplied to the electrode 120, the electric field F generated under a constant first voltage of the first AC power may also have a certain range as shown. have. Therefore, a certain region in which an electric field F is not formed may exist between the electrodes 120 spaced apart from each other. For this reason, droplets D1 of a relatively large size may be included and excited within the generated adjacent electric fields F, whereas fine droplets D2 may not be disposed and excited outside the electric fields F. . Therefore, the fine droplet D2 cannot be properly vibrated and may remain on the surface of the object O (ie, the lens 12), as shown in FIG. 9(c). If the range of the electric field F is expanded, such a fine droplet D2 may also be included in the expanded electric field F and vibrate and vibrate. As already discussed, since the range (or size) of the electric field F is proportional to the supplied voltage, in order to expand the range of the electric field F, after the supply step S30, the control device 400 is operated A second AC power having a second voltage greater than 1 voltage may be provided or supplied to the electrowetting device 100 (S40).

In more detail, in order to efficiently remove the droplet D, it may be advantageous that the supply step S40 is performed without interruption following the preceding supply step S30. For this continuity, in the supplying step (S40 ), the control device 400 may increase only the first voltage from the first AC power currently being supplied to the second voltage, as shown in FIG. 6 ( S41). However, it can be explained that, by changing to the second voltage, the control device 400 actually provides a second AC power different from the first AC power. In addition, only the voltage is changed for the expansion of the electric field F, and the second AC power provided for continuous excitation may have the same second frequency as the first frequency of the first AC power, that is, the resonance frequency. In addition, the second frequency (that is, the resonance frequency) of the supplied second AC power may be continuously maintained during the entire supplying step S40. The second voltage may be appropriately set to be greater than at least the first voltage, and may have a range of 150 V-200 V, for example. The electric field F may be expanded by supplying the second AC power (ie, the second voltage), and the relationship between the extended electric field and the fine droplet D2 is well illustrated in FIG. 11. Referring to FIG. 11, the electrode 120 may form an electric field F1 larger than the electric field F under the existing first voltage by the supplied second voltage. Fine droplets D2 may also be included in this extended electric field F1, and may be sufficiently excited and vibrated to be removed.

Furthermore, for more effective excitation of the small droplet D2, the control device 400 may reduce the second voltage of the second AC power source to the third voltage during the supplying step S40 (S42). That is, the control device 400 may supply the second AC power having the third voltage smaller than the second voltage to the electrowetting device 100. As illustrated in FIG. 11, a reduced electric field F2 may be formed rather than the electric field F1 at the second voltage by supplying the second AC power having the third voltage. However, even in this case, in order to continuously excite the fine droplet D2, the electric field F2 at the third voltage must be formed to include at least the fine droplet D2. Therefore, in order to form such an electric field F2, the third voltage may be set smaller than the second voltage but at least larger than the first voltage. Subsequently, the control device 400 may increase the third voltage of the second AC power to the second voltage and reduce the second voltage to the third voltage again, and repeatedly increase and decrease the voltage. Yes (S43). That is, the control device 400 may repeatedly supply the second AC power having the second voltage and the second AC power having the third voltage. Because of its small size and mass, the fine droplets D2 may not be easy to sufficiently excite even if they are included in the electric fields F1 and F2. However, as shown in FIG. 11, different ranges of electric fields F1, F2 alternately and alternately fine droplets D2 by alternate supply of different second and third voltages. It is applied, and thus an additional excitation force may be applied to the fine droplet D2. Therefore, the fine droplets D2 can also be vibrated appropriately, and the surface of the object O can be completely cleaned due to the removal of the fine droplets D2.

During the above-described supply step (S40), a second AC power having various voltages may be provided to the electrowetting device 100 for a predetermined second time period, the second time being a fine droplet D2 It can be appropriately set to cause a sufficient movement and removal of. More specifically, the control device 400 may monitor the surface of the object O using the sensing device 300, and even the second droplet AC power until the fine droplets D2 are completely removed from the surface. Can maintain the supply. In addition, as already discussed, the supply step (S30) is configured to remove most of the droplets (D1), while the supply step (S40) can be configured to remove only the remaining fine droplets (D2). Therefore, the first time in which the supplying step S30 is performed may be set longer than the second time in which the supplying step S40 is performed, for example, the ratio of the first time and the second time is 8:2. Can be set to

On the other hand, the modified example of the electrowetting device 100 shown in FIGS. 12-15 may exhibit a different behavior from the basic example in FIGS. 10 and 11 described above during actual operation. FIG. 16 is a schematic diagram showing the correlation between the range of the electric field and the size of droplets that can be excite in a modification of the electrowetting device, and FIG. 17 is expanded due to the increased voltage in the modification of the electrowetting device It is a schematic diagram showing fine droplets excited by an electric field.

When the first AC power having the resonant frequency and the first voltage is simultaneously supplied to these sub-electrodes 121a and 122a in the supply step S30, the first and second sub-electrodes 121a and 122a are electric fields. (Fa,Fb) can be formed (see FIG. 16). As described above, due to the alternating arrangement of the first and second sub-electrodes 121a and 122a, as shown in FIG. 16, the formed electric fields Fa and Fb are connected to each other to connect the object O to the It is possible to form a uniform electric field covering the entire surface. Therefore, not only the droplets D1 of a normal size but also any microdroplets D2 can be included in these connected electric fields Fa and Fb, and can be removed by being vibrated by these electric fields. For this reason, the modified example of the electrowetting device 100 can effectively remove all the droplets D1 and D2 of any size only by the step of supplying the first AC power (S30). Nevertheless, according to the control method of the present application, the above-described second AC power supply step (S40) may be additionally performed in a cleaning device including a modification of the electrowetting device 100. Accordingly, as illustrated in FIG. 17, the first and second sub-electrodes 121a and 122a may be formed by alternately alternating electric fields F1 and F2 in different ranges, and accordingly, the microdroplets D2 ) Can be removed more effectively. For the modified example of the electrowetting device 100, the same supply steps (S40: S41-S43) described above with reference to FIG. 6 are applied, and further description thereof will be omitted in the following.

As described above, since the modification example of the electrowetting device 100 has a more effective structure for removing droplets, the control method of the present application may be partially modified based on the modification example. As an example, the first AC power supply step (S30) may be modified when a modified example of the electrowetting device 100 is applied, and FIG. 18 shows the resonance frequency and the first voltage in the control method of the present application. It is a flow chart showing in detail the steps of providing the first AC power having.

Referring to FIG. 18, in the supplying step (S30 ), the control device 140 may first supply the first AC power only to the first electrode 121, that is, its first sub-electrodes 121a for a predetermined time ( S31). Thereafter, the control device 140 may continuously supply the first AC power only to the second electrode 122, that is, the second sub-electrodes 122a thereof for a predetermined time (S32 ). In addition, the control device 140 may repeatedly perform these supply steps (S31, S32). That is, the control device 140 may be configured to alternately supply the first AC power to the first and second electrodes 121 and 122. As previously described in detail in the supply step (S30), the first AC power supplied may have a resonance frequency and a first voltage. As described above, since the first and second electrodes 121 and 122 form electric fields covering the entire object surface, even the smallest microdroplets are formed by any one of the supply steps S31 and S32. It can be included in the electric field and can be vibrated appropriately. Rather, these alternating supply steps and the repetitions (S31-S33) thereof can periodically change the formation positions of the electric field, so that the microdroplets can be more effectively excited and removed.

On the other hand, when the object O is inclined, the droplet D on the object O (that is, the electrowetting device 100) is affected by gravity and can be moved more easily by this additionally applied force. Can be. Thus, referring to FIG. 4 again, the control device 400 may orient the object O and the electrowetting element 100 installed thereon in an inclined manner (S50). For example, as shown in FIG. 2, the camera 10 may include a predetermined driving device 14. The control device 400 may generate a displacement in the camera 10 using the driving device 14 and incline the object O to be cleaned, that is, the lens 12 and the electrowetting element 100. More specifically, the driving device 14 may be formed of a device capable of generating a rotational force, and as shown by an arrow in FIG. 1, at least the lens 12 and the element 100 are generated using the generated rotational force. It can be rotated to be inclined. The driving device 14 is exemplarily shown as being coupled to the lens body 11, but may also be coupled to other parts of the camera 10, and the orientation of the lens 12 and the electrowetting element 100 as objects to be cleaned. It can be made of any device capable of generating a driving force that changes. The alignment step S50 may be performed before or after the supply steps S40 and S50, and may be performed at any time during the supply steps S40 and S50. By such an alignment step (S50), the droplet (D) can be moved in a more smoothly inclined direction by gravity while vibrating, and can be more easily removed from the surface of the object (O).

The above detailed description should not be construed as limiting in all respects and should be considered illustrative. The scope of the present application should be determined by rational interpretation of the appended claims, and all changes within the equivalent scope of the present application are included in the scope of the present application.

Claims (22)

1. A substrate provided on the surface of a given object;

   An electrode provided on the substrate and including first and second electrodes respectively disposed in different planes;

   An insulating layer provided on the substrate and configured to cover the electrode; And

   And a control device configured to supply AC power to the electrode,

   The control device is configured to apply a first alternating current power source having a predetermined first frequency and a predetermined first voltage for a first time period to generate vibrations in droplets on the object surface by periodic changes in the electrostatic force generated by the electrodes. It is configured to provide to the electrode, the first frequency is the object surface cleaning apparatus is set to the resonance frequency of the droplet.
2. According to claim 1,

   The control device is configured to detect the resonant frequency of the droplet while providing AC power to the electrode before supplying the first AC power.
3. According to claim 2,

   While detecting the resonant frequency, the control device:

   Sequentially sweep frequencies in a predetermined range of the provided AC power;

   Sensing the resonance of the droplet during the sweep;

   And an object surface cleaning device configured to set the frequency at which the resonance occurs to the first frequency.
4. The method of claim 3,

   While sweeping the frequencies of the predetermined range, the control device is configured to gradually increase the frequency of the AC power source until a resonance occurs in the droplet starting from a predetermined frequency.
5. The method of claim 4,

   The control device is an object surface cleaning device configured to sweep frequencies of 10Hz-150Hz.
6. The method of claim 3,

   To detect the resonance of the droplet, the control device:

   Acquire an image of the droplet using a sensor;

   An object surface cleaning device configured to analyze the acquired image to detect a sharp increase in vibration of the droplet.
7. According to claim 1,

   When the resonance of the droplet is sensed at multiple frequencies, the control device is configured to set the highest frequency of the frequencies to the first frequency of the AC power.
8. According to claim 1,

   The first frequency is 30 Hz or 100 Hz object surface cleaning apparatus.
9. According to claim 1,

   The first voltage is an object surface cleaning apparatus having a range of 50V-150V.
10. According to claim 1,

    The control device is configured to provide a second AC power supply having a second voltage greater than the first voltage to the electrode for a second time after providing the first AC power supply during the first time period. .
11. The method of claim 10,

    The second voltage is an object surface cleaning apparatus having a range of 150V-200V.
12. The method of claim 10,

    In order to supply the second AC power, the control device is configured to increase the first voltage of the first AC power having the first frequency to the second voltage.
13. The method of claim 10,

    While providing the second AC power, the control device:

    Reducing the second voltage to a third voltage less than the second voltage;

    Then, increase the third voltage to the second voltage;

    And an object surface cleaning apparatus further configured to repeat the increase from the third voltage to the second voltage and the decrease from the second voltage to the third voltage.
14. The method of claim 10,

    The first time and the second time are set to 8:2 object surface cleaning apparatus.
15. According to claim 1,

    The first electrode is disposed on the substrate, and the second electrode is an object surface cleaning device disposed above the first electrode (above).
16. According to claim 1,

    The first electrode is spaced apart from each other at a predetermined interval, and includes a plurality of first sub-electrodes disposed in the same plane,

    The second electrode is spaced apart from each other at a predetermined interval, the object surface cleaning apparatus including a plurality of second sub-electrodes disposed in the same plane.
17. The method of claim 16,

    The first and second sub-electrodes are alternately disposed object surface cleaning apparatus.
18. The method of claim 16,

    The electrode surface cleaning apparatus including a predetermined first gap formed between a side of the first sub-electrode and a side of the second sub-electrode adjacent thereto.
19. The method of claim 18,

    The first interval is 5 ㎛ object surface cleaning apparatus.
20. According to claim 1,

    The insulating layer:

    A first insulating layer disposed on the substrate and configured to cover the first electrode; And

    And a second insulating layer disposed on the first insulating layer and configured to cover the second electrode.
21. According to claim 1,

    The electrode is an object surface cleaning apparatus including a second gap formed in a vertical direction between the first electrode and the second electrode.
22. According to claim 1,

    While providing the first AC power, the control device is configured to supply the first AC power alternately to the first and second electrodes.

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