Piezoelectric ultrasonic element and camera-mountable self-cleaning module

Abstract

Provided is a piezoelectric ultrasonic element. The piezoelectric ultrasonic element according to an embodiment of the present invention generates ultrasonic waves of sufficient performance to remove contaminants from a surface area of interest or prevent the attachment thereof, and can minimize performance degradation caused by rapid heating. The piezoelectric ultrasonic element according to an embodiment of the present invention comprises: a piezoelectric ceramic sintered body; a plurality of interdigitated electrodes disposed on the upper surface of the piezoelectric ceramic sintered body and inside the piezoelectric ceramic sintered body so as to be spaced a certain distance in the thickness direction from the upper surface, and including first branch electrodes and second branch electrodes alternately arranged on the same plane such that respective side surfaces face each other; and a pair of through-electrodes formed passing through at least a portion of the sintered body in the thickness direction of the piezoelectric ceramic sintered body to electrically connect the plurality of interdigitated electrodes spaced apart from each other in the thickness direction.

Description

Self-cleaning module for mounting piezoelectric ultrasonic elements and cameras

[0001] The present invention relates to a piezoelectric ultrasonic element and a self-cleaning module for mounting on a camera.

[0002] Piezoelectric ceramics are materials that generate voltage when pressure is applied and undergo mechanical deformation when an electric field is applied. They can convert mechanical vibration energy into electrical energy and vice versa, and are materials with very high conversion efficiency.

[0003] Accordingly, piezoelectric ceramics have been studied extensively as a basic material in the electronic field, and are being used in a wide range of fields from household use to high-tech fields, such as communication devices such as resonators, medical devices such as ultrasonic blood flow meters, transformers for LCD backlights, ultra-precision actuators, ultrasonic motors, transducers, various precision sensors and measuring and measuring instruments. In addition, with MEMS (Micro Electro Mechanical system) technology, the implementation of micro-sized actuators and sensors is becoming possible. In addition, recently, along with unidirectional piezoelectric ceramics that convert electrical / mechanical energy to mechanical / electrical energy, bidirectional second-generation piezoelectric ceramics that utilize both conversions simultaneously to exhibit new functions have been developed, expanding the scope of their applications.

[0004] Recently, research has been actively underway on technologies that utilize piezoelectric ceramics to generate ultrasonic waves to remove foreign matter from target surfaces or prevent their attachment. Specifically, contamination caused by water droplets, dust, and other foreign substances that can occur on the surface of externally installed camera lenses or on the surfaces of various camera covers within the field of view of the lens makes data collection and provision difficult. Manual cleaning of these contaminants is challenging. While it is possible to remove such contamination using devices such as wipers, which are installed separately, it can be difficult to remove the contamination when these devices are not readily available. However, ultrasonic waves generated by power applied to piezoelectric ceramics during contamination detection can remove foreign matter contaminating the target area or prevent its attachment. Furthermore, piezoelectric ceramics do not require a large installation space, and are therefore in demand for various camera devices used in various fields, such as electric vehicles.

[0005] However, the piezoelectric elements developed to date generate ultrasonic waves that are not sufficient to remove foreign substances on the surface, or generate serious heat due to the high voltage applied to generate sufficiently high ultrasonic waves, which may deteriorate the performance of the piezoelectric element itself and cause adverse effects on other adjacent electronic components.

[0006] The present invention has been devised in consideration of the above points, and its purpose is to provide a piezoelectric ultrasonic element and a method for manufacturing the same, which generates ultrasonic waves of sufficient performance to remove contaminated foreign substances from a target surface area or prevent the attachment of foreign substances, and minimizes performance deterioration due to rapid heat generation by minimizing the temperature rise rate despite the high voltage applied.

[0007] In addition, another object of the present invention is to provide a camera-mounted self-cleaning module that prevents short-circuiting of electrical connections within the module due to high voltage power applied to the piezoelectric ultrasonic element.

[0008] The present invention has been made in consideration of the above points, and provides a piezoelectric ultrasonic element including a piezoelectric ceramic sintered body, a plurality of interlocking electrodes including first branch electrodes and second branch electrodes which are spaced apart from the upper surface of the piezoelectric ceramic sintered body at a predetermined interval in the thickness direction from the upper surface and alternately arranged on the same plane so that their respective side surfaces face each other, and a pair of via electrodes which are formed by penetrating at least a portion of the sintered body in the thickness direction of the piezoelectric ceramic sintered body to electrically conduct electricity between the plurality of interlocking electrodes spaced apart from each other in the thickness direction.

[0009] According to one embodiment of the present invention, the piezoelectric ceramic sintered body may be a sintered body of at least one piezoelectric ceramic component selected from the group consisting of PZT, PMN, PNN, PT, PMW, PNN-PZT, PMN-PT, PMW-PZT, BS-PT, PLZT, PMW-PNN-PZT and PMN-PNN-PZT, a mixture of at least two or more thereof, or an alloy of at least two thereof, and a non-lead piezoelectric ceramic component selected from the group consisting of BT, KNN, SBN, BNKT and BNT, a mixture of at least two or more thereof, or an alloy of at least two thereof.

[0010] In addition, the first branch electrode and the second branch electrode within the interlocking electrode may be extended so that the major axis direction of the piezoelectric ceramic sintered body becomes the longitudinal direction, and may be spaced apart from each other in the minor axis direction of the piezoelectric ceramic sintered body.

[0011] In addition, the first branch electrode and the second branch electrode are connected to the first mother electrode and the second mother electrode, respectively, and one of the pair of via electrodes can be electrically connected to the first mother electrode and the other can be electrically connected to the second mother electrode.

[0012] Additionally, the width of the first branch electrode and the second branch electrode may be 250 to 450 μm, and the spacing between the first branch electrode and the second branch electrode may be 250 to 450 μm.

[0013] Additionally, the lower surface of the piezoelectric ceramic sintered body may further include terminal portions that are electrically connected to the via electrode and are spaced apart from each other.

[0014] Additionally, the length of the piezoelectric ceramic sintered body may be 18 mm, the width may be 3 mm, and the thickness may be 0.3 mm.

[0015]

[0016] In addition, the present invention provides a method for manufacturing a piezoelectric ultrasonic element, comprising: a step of manufacturing a laminate in which a plurality of piezoelectric ceramic green sheets are laminated, each of which has interlocking electrodes formed on one surface, each of which includes first and second branch electrodes alternately arranged so that their respective sides face each other; a step of forming a pair of via holes in the thickness direction of the laminate to electrically conduct adjacent interlocking electrodes within the laminate; a step of solidifying a via electrode composition filled in the pair of via holes to form a via electrode; and a step of sintering the laminate.

[0017]

[0018] In addition, the present invention provides a camera-mounted self-cleaning unit including: a transparent substrate portion having first and second surfaces facing each other and having a metal electrode disposed on the second surface; an electrowetting portion disposed on the first surface and having a transparent electrode and an insulating layer disposed on the transparent electrode; and at least one piezoelectric ultrasonic element portion disposed to be in electrical contact with the metal electrode of the second surface.

[0019] According to one embodiment of the present invention, the piezoelectric ultrasonic element unit may include a piezoelectric ultrasonic element according to the present invention.

[0020]

[0021] In addition, the present invention provides a camera-mounted self-cleaning module including a self-cleaning unit according to the present invention, a first circuit portion having a terminal disposed on one side of a transparent electrode in the self-clinic unit, a first anisotropic conductive portion electrically connecting between the transparent electrode in the electrowetting portion and the terminal in the first circuit portion, a second circuit portion having a terminal disposed on one side of a metal electrode in the self-clinic unit, and a second anisotropic conductive portion electrically connecting between the metal electrode in the self-clinic unit and the terminal in the second circuit portion.

[0022] According to one embodiment of the present invention, a metal layer is further provided on a transparent electrode electrically connected to a terminal of the first circuit portion, and the first anisotropic conductive portion can electrically connect the metal layer and the terminal of the first circuit portion.

[0023] In addition, terminals of the first circuit portion and the second circuit portion are respectively arranged on the transparent electrode and the metal electrode, and the first anisotropic conductive portion and the second anisotropic conductive portion may include a solder portion that electrically connects the transparent electrode and the metal electrode to the terminal, respectively, and an insulating binder portion that is arranged in a corresponding area between the transparent electrode or the metal electrode and the terminal where the solder portion is not arranged.

[0024] Additionally, the metal layer may have a thickness of 200 to 500 nm.

[0025] Additionally, the piezoelectric ultrasonic element portion within the self-cleaning unit may include a piezoelectric ultrasonic element according to the present invention.

[0026] In addition, when 300 V power is applied to the first circuit section and the second circuit section, a short circuit may not occur between the first circuit section and the transparent electrode, or between the second circuit section and the metal electrode.

[0027] The piezoelectric ultrasonic element according to the present invention generates ultrasonic waves with sufficient performance to remove contaminated foreign substances from a target surface area or prevent adhesion of foreign substances, and minimizes performance degradation due to rapid heat generation by minimizing the temperature rise rate despite the high voltage applied. In addition, a camera-mounted self-cleaning module implemented using such a piezoelectric ultrasonic element has excellent electrical connection durability between the terminals and electrodes of the circuit part even when a high voltage power source is applied to the piezoelectric ultrasonic element for generating ultrasonic waves, and thus can operate the ultrasonic element and electrowetting part normally for a long time, and can be widely used in applications that use power under various conditions.

[0028] Figure 1 is a cross-sectional view of a piezoelectric ultrasonic element according to one embodiment of the present invention;

[0029] FIG. 2 is a plan view of an interlocking electrode in a plane perpendicular to the thickness direction of a piezoelectric ultrasonic element according to one embodiment of the present invention;

[0030] Figure 3 is a cross-sectional view of a piezoelectric ultrasonic element according to another embodiment of the present invention;

[0031] Figures 4 and 5 are cross-sectional schematic diagrams of a self-cleaning module for mounting a camera according to various embodiments of the present invention, and

[0032] FIG. 6 is a photograph of a transparent substrate portion equipped with a metal electrode included in a self-cleaning unit according to one embodiment of the present invention.

[0033] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0034]

[0035] Referring to FIGS. 1 and 2, a piezoelectric ultrasonic element (200) according to one embodiment of the present invention includes a piezoelectric ceramic sintered body (100), a plurality of interlocking electrodes (11) spaced apart from an upper surface of the piezoelectric ceramic sintered body (100) in the thickness direction of the piezoelectric ceramic sintered body (100) and arranged inside the piezoelectric ceramic sintered body (100) at a predetermined distance from the upper surface in the thickness direction, and two via electrodes (110, 120) formed by penetrating at least a portion of the piezoelectric ceramic sintered body (100) in the thickness direction of the piezoelectric ceramic sintered body (100) to electrically conduct current between the plurality of interlocking electrodes (11). In addition, the interlocking electrodes (11) include a first branch electrode (11a1) and a second branch electrode (11b1) that are spaced apart from each other and arranged alternately so that their side surfaces face each other.

[0036]

[0037] The above piezoelectric ultrasonic element (200) is in a form that includes a plurality of piezoelectric ceramic unit parts (10, 20, 30, 40, 50, 60, 70, 80, 90) in the thickness direction, and the piezoelectric ceramic component in each piezoelectric ceramic unit part (10, 20, 30, 40, 50, 60, 70, 80, 90) forms a single body as a piezoelectric ceramic sintered body (100), and a plurality of interlocking electrodes (11) have a structure in which they are arranged to be spaced apart from each other in the thickness direction within the body.

[0038] In addition, the interlocking electrode (11) in each piezoelectric ceramic unit (10, 20, 30, 40, 50, 60, 70, 80, 90) includes a first branch electrode (11a1) and a second branch electrode (11b1) that are alternately arranged so that their sides face each other in a plane direction substantially perpendicular to the thickness direction of the piezoelectric ceramic sintered body (100).

[0039] The above interlocking electrode (11) forms an electric field by different power sources (e.g., (+), (-)) applied to the first branch electrode (11a1) and the second branch electrode (11b1), and the formed electric field induces compression and expansion in the piezoelectric ceramic sintered body in contact with the electrode surface of each interlocking electrode (11), thereby generating ultrasonic vibrations on a target surface, for example, the uppermost or lowermost surface in the thickness direction of the piezoelectric ceramic sintered body (100), and when the spacing / number / material between the first branch electrode (11a1) and the second branch electrode (11b1), the upper and lower spacing and number between the interlocking electrodes (11), the composition of the piezoelectric ceramic sintered body in contact with the interlocking electrode (11), etc. are appropriately adjusted, the intensity of the ultrasonic vibrations can be greatly implemented in the target direction, and thereby, contamination of foreign substances or water droplets on the target surface arranged in the thickness direction of the piezoelectric ceramic sintered body (100) can be prevented. If contaminated, it can be removed.

[0040]

[0041] When the interlocking electrode (11) has a structure in which the side surfaces of the first branch electrode (11a1) and the second branch electrode (11b1) are spaced apart from each other and alternately arranged so that they face each other, the present invention is not particularly limited to the structure of the entire interlocking electrode (11) including the first branch electrode (11a1) and the second branch electrode (11b1). For example, as illustrated in FIG. 2, each of the first branch electrode (11a1) and the second branch electrode (11b1) may extend in the major axis direction of the piezoelectric ceramic sintered body (100) and be spaced apart in the minor axis direction based on a plane perpendicular to the thickness of the piezoelectric ceramic sintered body (100), thereby more advantageously achieving the purpose of the present invention. On the other hand, when the interlocking electrode is formed in a structure in which it extends in the minor axis direction and is spaced apart in the major axis direction, the foreign substance removal ability may be reduced. In addition, each of the plurality of first branch electrodes (11a1) and second branch electrodes (11b1) may be branched from the first mother electrode (11a2) and the second mother electrode (11b2) having a predetermined area, but is not limited thereto.

[0042]

[0043] In addition, a plurality of interlocking electrodes (11) spaced apart from each other in the thickness direction can be electrically connected in the thickness direction, and specifically, can be electrically connected by via electrodes (110, 120) formed by penetrating the piezoelectric ceramic sintered body (100) in the thickness direction. At this time, the specific electrode structure design in which the first branch electrodes (11a1) are electrically connected to the first via electrode (110) in the thickness direction, and the second branch electrodes (11b1) are electrically connected to the second via electrode (120) in the thickness direction can employ a known electrode structure design without limitation, and thus the present invention is not particularly limited thereto. As a non-limiting example of this, as illustrated in FIGS. 1 and 2, a first mother electrode (11a2) and a second mother electrode (11b2) that connect a plurality of first branch electrodes (11a1) and second branch electrodes (11b1) may be connected to a first via electrode (110) and a second via electrode (120). The first via electrode (110) and the second via electrode (120) may have a diameter of, for example, 100 to 120 μm, which may be advantageous in achieving the purpose of the present invention, such as preventing an electrical short circuit.

[0044]

[0045] In addition, the material of the first branch electrode (11a1) and the second branch electrode (11b1), and the first mother electrode (11a2) and the second mother electrode (11b2) connecting them on the same plane, and the via electrodes (110, 120) connecting them on different planes, may be any known internal electrode material used in a piezoelectric element without limitation, and may be silver (Ag) as an example.

[0046]

[0047] In addition, the first branch electrode (11a1) and the second branch electrode (11b1) may each independently have a width of 250 to 450 μm, for example, 250 to 350 μm, a thickness of 5 to 10 μm, for example, a width of 300 μm, and a thickness of 5 μm. In addition, the spacing between adjacent first branch electrodes (11a1) and second branch electrodes (11b1) may be 250 to 450 μm, for example, 250 to 350 μm, for example, 300 μm. However, depending on the width of each of the first branch electrode (11a1) and the second branch electrode (11b1) and the spacing therebetween, the level of heat generation may vary even when ultrasonic vibrations are generated to achieve the desired level of removal ability for water droplets or foreign substances, and there is a concern that the heat generation may cause malfunctions in components and devices equipped with piezoelectric ultrasonic elements. Accordingly, preferably, the width of each of the first branch electrode (11a1) and the second branch electrode (11b1) may be 250 to 450 μm, and the spacing therebetween may be 250 to 450 μm.

[0048]

[0049] In addition, the interlocking electrode (11) including the first branch electrode (11a1) and the second branch electrode (11b1) may be arranged to occupy all or only a portion of a plane perpendicular to the thickness of the piezoelectric ceramic sintered body (100).

[0050]

[0051] Meanwhile, the exterior of the piezoelectric ultrasonic element (200) may further include a terminal portion as a connection portion for connecting the piezoelectric ultrasonic element (200) with an electrode, circuit, etc. for applying power to the above-described interlocking electrode (11). For example, as illustrated in FIG. 3, the lower surface of the piezoelectric ceramic sintered body (100) may include terminal portions (130) electrically connected to via electrodes (110, 120) on both sides of the longitudinal axis of the piezoelectric ceramic sintered body (100'). In addition, the terminal portion (130) may be arranged to form a part in the thickness direction of the piezoelectric ceramic unit portion (90') forming the lower surface of the piezoelectric ceramic sintered body (100'). Alternatively, the terminal portion may be arranged so as to be electrically connected to the via electrodes (110, 120) on the lower surface of the piezoelectric ceramic unit portion (90) arranged on the lower surface of the piezoelectric ceramic sintered body (100) differently from FIG. 3. However, it is not limited thereto, and for example, it can be formed on all or part of both short-axis direction sides of the piezoelectric ceramic sintered body (100).

[0052]

[0053] Next, the piezoelectric ceramic sintered body (100, 100') corresponding to the body forming the piezoelectric ultrasonic element (200, 200') is formed by integrating piezoelectric ceramic green sheets (12) within a plurality of piezoelectric ceramic unit parts (10, 20, 30, 40, 50, 60, 70, 80, 90) through a sintering process, and may be formed by stacking a plurality of piezoelectric ceramic green sheets formed through a piezoelectric ceramic composition and then sintering them.

[0054] Specifically, the piezoelectric ceramic green sheet may be known as a molded product in a pre-sintering state, and the present invention is not particularly limited with respect to the piezoelectric ceramic composition for manufacturing the piezoelectric ceramic green sheet, the method for manufacturing the green sheet, the size of the manufactured green sheet, etc.

[0055] For example, the piezoelectric ceramic green sheet (12) may be formed from a piezoelectric ceramic composition including a piezoelectric ceramic component, a binder, and a remaining amount of solvent.

[0056] The piezoelectric ceramic component may include one of the known lead-based piezoelectric ceramic components and the non-lead-based piezoelectric ceramic components that do not contain lead, a mixture thereof, or an alloy thereof. The lead-based piezoelectric ceramic component may be a known lead-based piezoelectric ceramic component, such as a perovskite type, a perovskite type composite, or one selected from the group consisting of lead titanate zirconate (PZT), lead magnesium niobate (PMN), lead nickel niobate (PNN), lead titanate (PT), lead magnesium tungstate (PMW), PNN-PZT, PMN-PT, PMW-PZT, BS-PT, and lanthanum-doped lead zirconate titanate (PLZT), a mixture of two or more, or an alloy of two or more, and non-limiting examples thereof include Pb(Ti, Zr)O3, Pb(Mg)O3, 1 / 3 Nb 2 / 3 )O3, Pb(Mg 1 / 3 Ta 2 / 3 )O3Pb(Ni 1 / 3 Nb 2 / 3 )O3, Pb(Mn 1 / 3 Ta 2 / 3 )O3Pb(Mn 1 / 3 Sb 2 / 3 )O3, Pb(Zn 1 / 3 Nb 2 / 3 )O3Pb(Zn 1 / 3 Ta 2 / 3 )O3, Pb(Mn 1 / 3 Nb 2 / 3 )O3Pb(Co 1 / 3 Sb 2 / 3 )O3, Pb(Zn 1 / 3 Nb 2 / 3 )O3Pb(Co 1 / 3 Nb 2 / 3 )O3, Pb(Fe 1 / 3 Sb 2 / 3 )O3Pb(Fe 1 / 3 Nb 2 / 3 )O3, Pb(Mn 1 / 3 Bi 2 / 3)O3, Pb(Mg 1 / 3 No 2 / 3 )O3, Pb(Mg 1 / 3 Dad 2 / 3 )O3Pb(Ni 1 / 3 No 2 / 3 )O3, Pb(Mn 1 / 3 Dad 2 / 3 )O3Pb(Mn 1 / 3 Sb 2 / 3 )O3, Pb(Zn 1 / 3 No 2 / 3 )O3Pb(Zn 1 / 3 Dad 2 / 3 )O3, Pb(Mn 1 / 3 No 2 / 3 )O3Pb(Co 1 / 3 Sb 2 / 3 )O3, Pb(Zn 1 / 3 No 2 / 3 )O3Pb(Co 1 / 3 No 2 / 3 )O3, Pb(Fe 1 / 3 Sb 2 / 3 )O3Pb(Fe 1 / 3 No 2 / 3 )O3, Pb(Mn 1 / 3 Bi 2 / 3 )O 3, Pb(Cd 1 / 2 W 1 / 2 )O3, Pb(Mg 1 / 2 W 1 / 2 )O3Pb(Co 1 / 2 W 1 / 2 )O3, Pb(Ni 1 / 2 W 1 / 2 )O3Pb(Mn 1 / 2 W 1 / 2 )O3, Pb(Ca 1 / 2 W 1 / 2 )O 3, Pb(Fe 2 / 3 W 1 / 3 )O3, Pb(Mn 2 / 3 W 1 / 3 )O 3, Sun(Mg 1 / 2 Tea 1 / 2 )O3, Nd(Mg 1 / 2 Tea 1 / 2 )O 3, Pb(Li 1 / 4 No 3 / 4 )O3, Pb(Cu 1 / 4 No3 / 4 )O3Pb(Li 1 / 4 Sb 3 / 4 )O3, etc. may be one or more kinds of mixtures or alloys selected from the group consisting of barium titanate (BT), KNN ((Na,K)NbO3), SBN ((Sr,B)Nb2O5), BNKT (Bi(Na,K)TiO3), and BNT ((Bi,Na)TiO3). As a specific example, the piezoelectric ceramic component may be a PMN-PNN-PZT system piezoelectric ceramic component. In addition, preferably, the piezoelectric ceramic component can be configured to satisfy a Qm value of the piezoelectric ceramic sintered body to be implemented of 500 or more, or for example, 600 or more, 700 or more, 800 or more, 900 or more, 1000 or more, 1100 or more, or 3000 or less, thereby implementing a function of removing water droplets and foreign substances through ultrasonic waves while reducing heat generation, thereby preventing deterioration of physical properties during operation and improving long-term durability, etc.

[0057]

[0058] Additionally, the binder may be any known binder used in the manufacture of molded articles using ceramic components without limitation. For example, the binder may be one or more of an acrylic binder, polyvinyl butyral, polyvinyl alcohol, etc.

[0059]

[0060] In addition, the solvent may be a known solvent that is advantageous for dispersing the above-described piezoelectric ceramic component and does not inhibit the dissolution of the binder, and may be, for example, a mixed solvent of one or two or more organic solvents such as toluene or ethanol.

[0061]

[0062] In addition, the piezoelectric ceramic composition may further include known plasticizers, dispersants, anti-foaming agents, etc. in addition to the described components, and the present invention is not particularly limited thereto.

[0063]

[0064] In addition, the piezoelectric ceramic composition contains a binder in an amount of 5 to 15 wt%, more preferably 5 to 12 wt%, based on the total weight of the composition. If the binder is contained in an amount of less than 5 wt%, it may not be easy to manufacture a piezoelectric ceramic molded product. If the binder is contained in an amount of more than 15 wt%, the carbon content remaining after firing may increase, and since the content of the piezoelectric ceramic component is relatively reduced, it may be difficult to exhibit sufficient piezoelectric performance.

[0065]

[0066] In addition, the piezoelectric ceramic component may be contained in an amount of 12 to 30 wt%, and the solvent may be contained in the remainder. In addition, when additives such as a plasticizer or dispersant are contained, the content of the additives may be 1 to 4 wt%, but is not limited thereto.

[0067]

[0068] In addition, the piezoelectric ceramic composition described above can be formed into a piezoelectric ceramic green sheet, for example, by a tape casting method, but is not limited thereto. In addition, the formed piezoelectric ceramic green sheet (12) can have a thickness of, for example, 20 to 150 μm.

[0069]

[0070] In addition, the piezoelectric ceramic sintered body (100, 100') may have, for example, a length in the longitudinal direction of 15 to 20 mm, a width of 2.5 to 4.0 mm, and a thickness of 0.2 to 0.4 mm, and as a specific example, a length of 18 mm, a width of 3 mm, and a thickness of 0.3 mm.

[0071]

[0072] In addition, the implemented piezoelectric ultrasonic element (200, 200') may have a capacitance of 500 pF or more, through which the intended performance can be sufficiently expressed.

[0073]

[0074] The piezoelectric ultrasonic element (200) according to one embodiment of the present invention described above can be manufactured by including the steps of manufacturing a laminate in which a plurality of piezoelectric ceramic green sheets are laminated, each of which has interlocking electrodes formed on one surface, each of which includes first branch electrodes and second branch electrodes spaced apart from each other so that their side surfaces face each other, a step of forming a pair of via holes in the thickness direction of the laminate in order to electrically conduct electricity between interlocking electrodes adjacent in the thickness direction within the laminate, a step of forming a via electrode within the pair of via holes, and a step of sintering the laminate.

[0075]

[0076] First, a step for manufacturing a laminate in which a plurality of piezoelectric ceramic green sheets having interlocking electrodes formed on one surface are laminated will be described as the first step of the present invention.

[0077] The above piezoelectric ceramic green sheet is formed into a sheet shape with a piezoelectric ceramic composition having a predetermined thickness, and interlocking electrodes are formed on the piezoelectric ceramic green sheet. The above piezoelectric ceramic composition may be the piezoelectric ceramic composition described above, and a detailed description thereof is omitted.

[0078] In addition, the laminate can be prepared by laminating individual green sheets in the thickness direction and then applying a predetermined pressure, and can be prepared by a known method for implementing a laminated ceramic element, so a detailed description thereof is omitted in the present invention.

[0079]

[0080] Next, as the second step of the present invention, a step of forming a pair of via holes in the thickness direction of the laminate is performed to electrically conduct current between interlocking electrodes adjacent in the thickness direction within the laminate.

[0081] The above via hole can be formed to partially or completely penetrate the thickness direction of the laminate through a known method, and the present invention is not particularly limited thereto.

[0082] In addition, the via hole may be formed at an appropriate position so that two branch electrodes within a plurality of interlocking electrodes spaced apart in the thickness direction can be electrically connected to each other to which the same power is applied. For example, when the interlocking electrode includes a first mother electrode connected to a first branch electrode and a second mother electrode connected to a second branch electrode, a pair of via holes may be formed to penetrate the green sheet region where the first mother electrode and the second mother electrode are formed.

[0083]

[0084] Next, as the third step of the present invention, a step of forming a via electrode within a pair of via holes is performed.

[0085] The above via electrode can be formed by filling an electrode composition into a via hole and then going through a conventional drying process, and the electrode composition can be formed using a known electrode composition for forming an internal electrode in a multilayer ceramic device, so the present invention is not particularly limited to the specific composition of the electrode composition or the specific process for forming the electrode.

[0086]

[0087] Next, as the fourth step of the present invention, a step of sintering the laminate is performed.

[0088] In step 4, the laminated piezoelectric ceramic green sheet and the interlocking electrode and via electrode can be integrally freeze-sintered.

[0089] The sintering temperature of the above laminate can be sintered under known sintering conditions considering the composition of the piezoelectric ceramic green sheet, and the present invention is not particularly limited thereto. For example, when the piezoelectric ceramic green sheet contains a PMW-PNN-PZT piezoelectric ceramic component, it can be sintered at 1230 to 1260°C for 2 to 4 hours at a heating rate of 2 to 5°C / min in an air atmosphere, but is not limited thereto.

[0090] In addition, after firing, it can be cooled at a cooling rate of 1 to 3°C / min or left at room temperature to cool naturally, and the present invention is not particularly limited thereto.

[0091] Meanwhile, a further calcination step may be performed to remove the binder component within the piezoelectric ceramic green sheet prior to sintering. The calcination may be performed under conditions known in the art, taking into account the type of binder used. For example, the calcination may be performed at a temperature of 240 to 285°C, but is not limited thereto.

[0092]

[0093] In addition, referring to FIG. 4, the present invention includes a camera-mounted self-cleaning unit (300) having a piezoelectric ultrasonic element (320).

[0094] Specifically, a self-cleaning unit (300) for mounting a camera includes a transparent substrate portion (310) having a first side and a second side, an electrowetting portion (330) provided on the first side of the transparent substrate portion (310), and a piezoelectric ultrasonic element portion (320) provided on the second side, and can be advantageous in more effectively removing foreign substances contaminating the first side of the transparent substrate portion (310) through an electrowetting method and a mechanical vibration method using ultrasonic waves.

[0095]

[0096] The above transparent substrate portion (310) functions as a cover member for protecting and isolating a camera unit (not shown) to be placed on the lower side of the second surface of the transparent substrate portion (310) from the outside, and at the same time functions as a support member for supporting a piezoelectric ultrasonic element portion (320) and an electrowetting portion (330) placed on the transparent substrate portion (310).

[0097] In addition, the transparent substrate portion (310) is optically transparent so as not to affect the intensity of various signals such as light incident from the outside to the camera unit, and for this purpose, may include a transparent substrate layer (311). The transparent substrate layer (311) may be a known material having transparency such as various types of glass or plastic, and the present invention is not particularly limited thereto.

[0098]

[0099] In addition, a metal electrode (312) is provided on the second surface side of the transparent substrate layer (311) for electrically connecting the piezoelectric ultrasonic element (320) to the circuit section, and the present invention is not particularly limited with respect to the material, size, and electrode pattern shape of the metal electrode (312).

[0100]

[0101] In addition, a piezoelectric ultrasonic element (320) is disposed on the second surface side of the transparent substrate portion (310) to remove foreign substances such as dust, water droplets, mud, and insects that may contaminate the first surface side of the transparent substrate portion (310) by mechanical vibration. The piezoelectric ultrasonic element portion (320) may include at least one or more known piezoelectric ultrasonic elements capable of generating ultrasonic waves without limitation, and may include, for example, the piezoelectric ultrasonic element (200) according to one embodiment of the present invention described above.

[0102]

[0103] In addition, an electrowetting unit (330) is arranged on the first surface side of the transparent substrate portion (310). The electrowetting unit (330) is responsible for the function of removing droplets from the transparent substrate portion (310) through droplet control, such as forming, moving, or coalescing into larger droplets or separating into smaller droplets, moisture such as frost or raindrops formed on the first surface side of the transparent substrate portion (310) into droplets through power applied to the electrowetting unit (330).

[0104] The above electrowetting portion (330) includes a transparent electrode (331) and an insulating layer (332) formed on the transparent electrode (331).

[0105] The above transparent electrode (331) is formed of a transparent, known electrode material so as not to affect signals such as light incident on the camera unit to be spaced apart from the second surface of the transparent substrate portion (310), and may be, for example, ITO. In addition, the transparent electrode (331) may be formed of any known electrode pattern used in electrowetting technology without limitation, and for example, an interlocking electrode pattern may be formed.

[0106] In addition, the insulating layer (332) can be used without limitation in the case of a known insulating layer used in electrowetting technology, and for example, HfO2, ZrO2, Al2O3, SiO2, and SiN x It may include one or more of the following:

[0107] Additionally, a hydrophobic film (not shown) formed on the insulating layer (332) may be optionally further included to facilitate droplet formation and movement. The hydrophobic film may be formed of a known hydrophobic material, and the present invention is not particularly limited thereto.

[0108]

[0109] Also, referring to FIG. 4, the present invention includes a camera-mounted self-clinic module (1000) including the camera-mounted self-clinic unit (300) described above.

[0110] Specifically, the camera-mounted self-clinic module (1000) includes a first circuit unit (500) for controlling the operation of an electrowetting unit (330) in the camera-mounted self-clinic unit (300), a second circuit unit (400) for controlling the operation of a piezoelectric ultrasonic element unit (320), a first anisotropic conductive unit (600A) for electrically connecting a transparent electrode (331) in the electrowetting unit (330) and a terminal in the first circuit unit (500), and a second anisotropic conductive unit (600B) for electrically connecting a metal electrode (312) in the self-clinic unit (300) and a terminal (not shown) in the second circuit unit (400).

[0111]

[0112] The first circuit part (500) and the second circuit part (400) above have a function of controlling the operation of the electrowetting part (330) and the piezoelectric ultrasonic element part (320) that are electrically connected to them, respectively, and include various elements for operation control mounted on a printed circuit board such as an FPCB and terminals that are electrically connected to a transparent electrode (331) or a metal electrode (312).

[0113]

[0114] In addition, the first anisotropic conductive portion (600A) is provided to mediate an electrical connection between the terminal of the first circuit portion (500) and the transparent electrode (331) in the electrowetting portion (330). In addition, the second anisotropic conductive portion (600B) is provided to mediate an electrical connection between the terminal of the second circuit portion (400) and the metal electrode (312) in the transparent substrate portion (310). The self-clinic unit (300) for mounting a camera according to the present invention may be applied with a high voltage of 300 V or more in order to exhibit a sufficient level of wetting and foreign substance removal ability. However, the applied high voltage may easily cause an electrical short circuit between each circuit portion terminal and the metal electrode or transparent electrode, and in particular, an electrical short circuit may occur more frequently between the circuit portion terminal and the transparent electrode. In addition, since the present invention adopts both an electrowetting method and a mechanical vibration method for removing foreign substances, when the camera-mounted self-clinic unit (300) is driven, mechanical vibration due to ultrasonic waves generated from the piezoelectric ultrasonic element (320) is inevitably transmitted to the first circuit unit (500) and the second circuit unit (400) connected thereto, and thus there is a problem of frequent electrical short-circuits between the transparent electrode (331) and the metal electrode (312) and the terminals within each circuit unit. However, the anisotropic conductive portion is advantageous in maintaining continuous electrical connection even with frequent mechanical vibrations transmitted due to the driving of the camera-mounted self-clinic unit (300) in comparison to other methods of electrical connection.

[0115]

[0116] The first anisotropic conductive portion (600A) and the second anisotropic conductive portion (600B) may be formed through a member commonly referred to as an anisotropic conductive (or conductive) film (ACF) in the electrical and electronic field, and the present invention is not limited thereto with respect to its specific composition, etc. However, preferably, the first anisotropic conductive portion (600A) and the second anisotropic conductive portion (600B) may be formed through an anisotropic conductive film containing solder particles instead of an anisotropic conductive film typically containing metal particles such as nickel, and through this, the metal particles in the anisotropic conductive portion go beyond simply electrically connecting the electrodes and terminals through physical contact by filling the space between them, and the solder particle(s) are fused and bonded to each of the electrodes and the terminal, thereby further increasing the electrical connection durability even when subjected to high voltage applied and / or continuously transmitted mechanical vibration. The solder particles may be particles formed of a material used as solder, or may be particles having a core-shell structure in which a shell portion of solder material is formed on a core portion, which is a metal particle contained in a typical anisotropic conductive film. The solder may be formed of one or more materials, such as tin or lead, for example.

[0117] Accordingly, specifically, the first anisotropic conductive portion (600A) and the second anisotropic conductive portion (600B) may include one or more solder portions (620) fused to the electrodes and the terminals, respectively, in the separation space between the transparent electrode (331) and the metal electrode (312) and the terminals, and an insulating binder portion (610) disposed in the remaining space of the separation space where the solder portions (620) are not disposed.

[0118] In addition, electrical connection through fusion between solder particle(s) and terminal, solder particle(s) and electrode can be performed by applying one or more means of heat, compression, and ultrasonic irradiation, and the present invention is not particularly limited thereto.

[0119]

[0120] Meanwhile, referring to FIG. 5, a metal layer (333) is further provided on a transparent electrode (331) that is electrically connected to a terminal of a first circuit unit (500), and a first anisotropic conductive portion (600A), specifically, a solder portion (620) within the first anisotropic conductive portion (600A), can fuse the metal layer (333) and the terminal of the first circuit unit (500), thereby further preventing a short circuit between the first anisotropic conductive portion (600A) and the transparent electrode (331) even when a high voltage is applied to the electrowetting portion (330) through the first circuit unit (500) and / or when frequent vibrations are transmitted from the high-voltage ultrasonic element unit (320). That is, the high voltage applied to exhibit high wetting and foreign matter removal performance may particularly deteriorate the electrical connection durability between the transparent electrode (331) and the terminal of the first circuit unit (500) due to the material properties of the transparent electrode (331) compared to the electrical connection durability between the metal electrode (312) and the terminal of the second circuit unit (400). However, the metal layer (333) formed on the transparent electrode (331) can further increase the electrical connection durability even when a high voltage is applied and / or continuous mechanical vibration is transmitted by increasing the compatibility with the solder portion (620) of the first anisotropic conductive portion (600A). The metal layer (333) can be used without limitation as long as it is a metal to which solder can be applied, and for example, it can be formed of one type such as copper, nickel, aluminum, silver, gold, or platinum, and preferably, it can be formed of copper. In addition, the metal layer (333) may have a thickness of 200 to 500 nm, which is advantageous in further securing electrical connection durability, and accordingly, even when a power of 300 V or more is applied to the piezoelectric ultrasonic element (320), a short circuit may not occur between the first circuit unit (500) and the transparent electrode (331), or between the second circuit unit (400) and the metal electrode (312).

[0121]

[0122] Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiment presented in this specification, and a person skilled in the art who understands the spirit of the present invention will be able to easily propose other embodiments by adding, changing, deleting, or adding components within the scope of the same spirit, but this will also be considered to fall within the spirit of the present invention.

Claims

1. Piezoelectric ceramic sintered body; A plurality of interlocking electrodes including first and second branch electrodes arranged alternately on the same plane so that each side faces each other, spaced apart from the upper surface of the piezoelectric ceramic sintered body at a predetermined interval in the thickness direction from the upper surface; and A piezoelectric ultrasonic element comprising a pair of via electrodes formed by penetrating at least a portion of a piezoelectric ceramic sintered body in the thickness direction to electrically conduct electricity between a plurality of interlocking electrodes spaced apart in the thickness direction.

2. In paragraph 1, The above piezoelectric ceramic sintered body is a lead-based piezoelectric ceramic component which is one kind, two or more kinds of mixtures or two or more kinds of alloys selected from the group consisting of PZT, PMN, PNN, PT, PMW, PNN-PZT, PMN-PT, PMW-PZT, BS-PT, PLZT, PMW-PNN-PZT and PMN-PNN-PZT, and A piezoelectric ultrasonic element comprising at least one piezoelectric ceramic component sintered from among a non-lead piezoelectric ceramic component selected from the group consisting of BT, KNN, SBN, BNKT and BNT, a mixture of two or more components or an alloy of two or more components.

3. In paragraph 1, A piezoelectric ultrasonic element in which the first branch electrode and the second branch electrode are extended so that the long axis direction of the piezoelectric ceramic sintered body becomes the longitudinal direction and are mutually spaced apart in the short axis direction of the piezoelectric ceramic sintered body.

4. In paragraph 1, A piezoelectric ultrasonic element in which the first branch electrode and the second branch electrode are connected to the first mother electrode and the second mother electrode, respectively, and one of the pair of via electrodes is electrically connected to the first mother electrode and the other is electrically connected to the second mother electrode.

5. In paragraph 1, A piezoelectric ultrasonic element in which the width of the first branch electrode and the second branch electrode is 250 to 450 μm, and the spacing between the first branch electrode and the second branch electrode is 250 to 450 μm.

6. In paragraph 1, A piezoelectric ultrasonic element further comprising a terminal portion electrically connected to a via electrode and spaced apart from each other on the lower surface of the piezoelectric ceramic sintered body.

7. In paragraph 1, A piezoelectric ultrasonic element having a length of 18 mm, a width of 3 mm, and a thickness of 0.3 mm of the above piezoelectric ceramic sintered body.

8. A transparent substrate portion having a first surface and a second surface facing each other and a metal electrode disposed on the second surface; An electrowetting unit disposed on the first surface and having a transparent electrode and an insulating layer provided on the transparent electrode; and A camera-mounted self-cleaning unit comprising at least one piezoelectric ultrasonic element section arranged to be in electrical contact with the metal electrode of the second surface and including a piezoelectric ultrasonic element according to any one of claims 1 to 7.

9. Self-cleaning unit according to Article 8; A first circuit portion in which a terminal is placed on one side of a transparent electrode within a self-clinic unit; A first anisotropic conductive portion that electrically connects between the transparent electrode and a terminal in the first circuit portion; A second circuit portion in which the terminal is placed on one side of the metal electrode within the self-clinic unit; and A camera-mounted self-cleaning module comprising a second anisotropic conductive member electrically connecting between the metal electrode and a terminal in a second circuit section.

10. In paragraph 9, A metal layer is further provided on the transparent electrode that is electrically connected to the terminal of the first circuit section, A camera-mounted self-cleaning module in which the first anisotropic conductive portion electrically connects the metal layer and the terminal of the first circuit portion.

11. In paragraph 9, The terminals of the first circuit part and the second circuit part are respectively arranged on the upper part of the transparent electrode and the metal electrode, A camera-mounted self-cleaning module, wherein the first anisotropic conductive portion and the second anisotropic conductive portion include a solder portion that electrically connects the transparent electrode and the metal electrode, respectively, to the terminal, and an insulating binder portion that is disposed in a corresponding area between the transparent electrode or the metal electrode and the terminal, where the solder portion is not disposed.

12. In paragraph 10, A self-cleaning module for mounting a camera, wherein the metal layer has a thickness of 200 to 500 nm.

13. In paragraph 9, A self-cleaning module for mounting on a camera, characterized in that when a voltage of 300 V is applied to the first circuit section and the second circuit section, no short circuit occurs between the first circuit section and the transparent electrode, and no short circuit occurs between the second circuit section and the metal electrode.

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