Patent Publication Number: US-2022233887-A1

Title: Ultrasound mask and skin care device comprising same

Description:
TECHNICAL FIELD 
     An embodiment relates to an ultrasound mask that promotes beauty using an ultrasonic wave having a mid-frequency or low-frequency band of 1 MHz or less. 
     The embodiment relates to an ultrasound mask that may form a plurality of resonances in the vicinity of a specific frequency and promotes beauty using ultrasonic waves. 
     BACKGROUND ART 
     Human skin may be damaged or contaminated depending on external factors such as environmental pollution, ultraviolet rays, stress, and the like, and wrinkles may occur due to internal factors such as aging, hormonal changes, and the like. Recently, as interest in the skin has increased, various devices for skin treatment, beauty, and anti-aging have been developed. 
     In detail, a device has been developed, which is capable of applying thermal energy to the skin, for example, a device capable of improving skin elasticity by applying infrared energy. In addition, a device using sound waves or light rays has been developed in order to effectively inject cosmetics or drugs into the skin. For example, a device has been developed, which is capable of forming a path through which cosmetics or drugs are injected into the skin using sonophoresis and laserporation. In addition, a device using electric propulsion force has been developed in order to effectively inject cosmetics or drugs into the skin. For example, a device has been developed, which is capable of effectively injecting ionic substances contained in cosmetics or drugs into the skin using iontophoresis, electroporation, and electroosmosis. That is, various devices have been developed, which is capable of caring or treating a user&#39;s skin by providing light energy, microcurrent, vibration, or the like to the skin. 
     In general, the above-described devices may be provided in a form of a patch detachable to the skin, and the devices are attached to a specific skin region to care or treat the skin of the attached region. In addition, the above-described devices are provided in a form of a mask pack disposed to cover the entire user&#39;s face to care or treat the facial skin. 
     However, the devices have a problem that it is difficult to effectively adhere to curved skin surfaces such as both cheeks, nose, and the like. In detail, it may be difficult to effectively adhere to the user&#39;s skin due to materials and variable characteristics of the device. Accordingly, the device may be operated in a state in which the device is not completely adhered to the user&#39;s skin, and the device may be separated from the user&#39;s skin due to the user&#39;s movement or vibration of the device during the operation thereof. 
     In this case, there is a problem that it is difficult for the user to check whether the device is adhered to the skin, and thus, it is difficult to effectively obtain a care effect through the device. 
     In addition, since the device is applied to a region having various shapes such as a human&#39;s face, stretch and restoration characteristics are required, and there is a problem that an internal wiring or the like is damaged due to the characteristics. 
     Therefore, a new mask capable of solving the above-described problem is required. 
     DISCLOSURE 
     Technical Problem 
     An embodiment is to provide an ultrasound mask capable of easily delivering a substance used for cosmetics or medical purposes to the skin of the human body and having improved reliability. 
     An embodiment is to provide a piezoelectric member capable of forming a plurality of resonances in a flexion mode and an ultrasound mask including the same. 
     Technical Solution 
     An ultrasound mask according to an embodiment includes: a first substrate; a first wiring disposed on an upper surface of the first substrate; a second substrate disposed above the first substrate; a second wiring disposed on a lower surface of the second substrate; a piezoelectric member between the first substrate and the second substrate; a first electrode connected to the first wiring and disposed on a lower surface of the piezoelectric member; and a second electrode connected to the second wiring and disposed on an upper surface of the piezoelectric member, wherein the first wiring and the second wiring have a curvature (mm) of 5R to 15R, and the piezoelectric member generates an ultrasonic wave having a frequency band of 20 kHz to 1 MHz. 
     Advantageous Effects 
     The ultrasound mask according to the embodiment can easily transfer a material into the skin of the human body using ultrasonic waves. 
     In detail, cosmetic substances such as cosmetics can be easily delivered according to a position, shape, and size of an object to be worn by a user through a rigid piezoelectric member, a flexible substrate, and a wiring. 
     In addition, when the user wears the ultrasound mask through the substrate and the wiring that can be stretched and restored, it is possible to prevent an electrode from being damaged due to deformation of the ultrasound mask. 
     In addition, it is possible to minimize the loss of ultrasonic waves generated during transmission by controlling the directionality of the ultrasonic waves generated from the piezoelectric member by the matching layer and the backing layer. 
     In addition, it is possible to minimize the loss of ultrasonic waves generated during transmission by controlling thicknesses of the matching layer and the backing layer and controlling the movement of ultrasonic waves according to the frequency band of the ultrasonic waves generated from the piezoelectric member. 
     In addition, when the ultrasound mask is stretched or restored, the first wiring and the second wiring having a shape of continuous curvature patterns are stretched or restored together like a spring, and thus a stress effect due to stretch or restoration can be minimized. 
     In addition, since the first wiring extends only in a first direction and the second wiring extends only in a second direction, it is possible to minimize the constraints depending on the direction when the ultrasound mask according to the first embodiment is stretched or restored. That is, it is possible to improve the flexibility of the ultrasound mask. 
     In addition, the ultrasound mask according to the embodiment can easily transfer a material into the skin of the human body using ultrasonic waves. 
     In detail, since the piezoelectric member of the ultrasound mask according to the embodiment can emit ultrasonic waves in a thickness direction by oscillating ultrasonic waves in a flexion mode, the piezoelectric member can oscillate the ultrasonic waves in a wide region of the skin. 
     In addition, since the piezoelectric member of the ultrasound mask according to the embodiment can radiate the ultrasonic waves in the flexion mode in at least three frequency bands, the ultrasound mask can be used with ultrasonic waves in an appropriate frequency band according to the user&#39;s skin condition, and accordingly, it is possible to prevent a decrease in transmission efficiency of ultrasonic waves depending on the user&#39;s skin condition. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a view illustrating a top surface of an ultrasound mask according to an embodiment. 
         FIG. 2  is a view illustrating an enlarged top view of region A in  FIG. 1 . 
         FIG. 3  is a view illustrating a top view of a first substrate of an ultrasound mask according to a first embodiment. 
         FIG. 4  is a view illustrating a top view of a second substrate of the ultrasound mask according to the first embodiment. 
         FIG. 5  is a view illustrating a top view in which the first substrate and the second substrate of the ultrasound mask according to the first embodiment overlap. 
         FIG. 6  is a view illustrating a cross-sectional view taken along line B-B′ in  FIG. 5  of the ultrasound mask according to the first embodiment. 
         FIG. 7  is a view illustrating a cross-sectional view taken along line C-C′ in  FIG. 5  of the ultrasound mask according to the first embodiment. 
         FIGS. 8 and 9  are views illustrating cross-sectional views of the first substrate and the second substrate of the ultrasound mask according to the first embodiment. 
         FIG. 10  is a view illustrating another top view of a first substrate of an ultrasound mask according to a second embodiment. 
         FIG. 11  is a view illustrating another top view of a second substrate of the ultrasound mask according to the second embodiment. 
         FIG. 12  is a view illustrating a top view in which the first substrate and the second substrate of the ultrasound mask according to the second embodiment overlap. 
         FIG. 13  is a view illustrating a cross-sectional view taken along line D-D′ in  FIG. 12  of the ultrasound mask according to the second embodiment. 
         FIG. 14  is a view illustrating a cross-sectional view taken along line E-E′ in  FIG. 12  of the ultrasound mask according to the second embodiment. 
         FIG. 15  is a view illustrating another top view of a first substrate of an ultrasound mask according to a third embodiment. 
         FIG. 16  is a view illustrating another top view of a second substrate of the ultrasound mask according to the third embodiment. 
         FIG. 17  is a view illustrating a top view in which the first substrate and the second substrate of the ultrasound mask according to the third embodiment overlap. 
         FIG. 18  is a view illustrating a cross-sectional view taken along line F-F′ in  FIG. 17  of the ultrasound mask according to the third embodiment. 
         FIG. 19  is a view illustrating a cross-sectional view t taken along line G-G′ in  FIG. 17  of the ultrasound mask according to the third embodiment. 
         FIG. 20  is a view illustrating a cross-sectional view taken along line B-B′ in  FIG. 5  of an ultrasound mask according to a fourth embodiment. 
         FIG. 21  is a view illustrating a cross-sectional view taken along line B-B′ in  FIG. 5  of an ultrasound mask according to a fifth embodiment. 
         FIG. 22  is a view illustrating a cross-sectional view taken along line B-B′ in  FIG. 5  of an ultrasound mask according to a sixth embodiment. 
         FIG. 23  is a view illustrating an enlarged view of region D in  FIG. 6 . 
         FIG. 24  is a view illustrating a perspective view of a piezoelectric member according to an embodiment. 
         FIG. 25  is an exploded perspective view of the piezoelectric member according to the embodiment. 
         FIGS. 26A to 26C  are cross-sectional views of  FIG. 24  and a view illustrating various shapes of the piezoelectric member. 
         FIGS. 27A to 30  are views for describing a manufacturing process of the ultrasound mask according to the first to third embodiments. 
         FIGS. 31A to 35  are views for describing a manufacturing process of the ultrasound mask according to the fourth to sixth embodiments. 
         FIGS. 36 and 37  are views for describing an overlapping relationship between an adhesive layer and an electrode of the ultrasound mask according to the embodiment. 
         FIG. 38  is a view illustrating another top surface of the ultrasound mask according to the embodiment. 
         FIG. 39  is a view illustrating another cross-sectional view taken along line B-B′ in  FIG. 5 . 
         FIGS. 40 and 41  are views for describing the arrangement of cosmetic ingredients according to a spacer. 
         FIGS. 42 and 43  are views for describing a position of the spacer of the ultrasound mask according to the embodiment. 
         FIGS. 44 and 45  are side views of an ultrasound mask according to another embodiment. 
     
    
    
     MODES OF THE INVENTION 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the spirit and scope of the present invention is not limited to a part of the embodiments described, and may be implemented in various other forms, and within the spirit and scope of the present invention, one or more of the elements of the embodiments may be selectively combined and replaced. 
     In addition, unless expressly otherwise defined and described, the terms used in the embodiments of the present invention (including technical and scientific terms may be construed the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, and the terms such as those defined in commonly used dictionaries may be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art. 
     In addition, the terms used in the embodiments of the present invention are for describing the embodiments and are not intended to limit the present invention. In this specification, the singular forms may also include the plural forms unless specifically stated in the phrase, and may include at least one of all combinations that may be combined in A, B, and C when described in “at least one (or more) of A (and), B, and C”. 
     Further, in describing the elements of the embodiments of the present invention, the terms such as first, second, A, B, (A, and (b) may be used. These terms are only used to distinguish the elements from other elements, and the terms are not limited to the essence, order, or order of the elements. 
     In addition, when an element is described as being “connected”, “coupled”, or “connected” to another element, it may include not only when the element is directly “connected” to, “coupled” to, or “connected” to other elements, but also when the element is “connected”, “coupled”, or “connected” by another element between the element and other elements. 
     Further, when described as being formed or disposed “on (over)” or “under (below)” of each element, the “on (over)” or “under (below)” may include not only when two elements are directly connected to each other, but also when one or more other elements are formed or disposed between two elements. 
     Furthermore, when expressed as “on (over)” or “under (below)”, it may include not only the upper direction but also the lower direction based on one element. 
     Hereinafter, an ultrasound mask according to embodiments will be described with reference to the drawings. 
       FIG. 1  is a view illustrating an ultrasound mask according to an embodiment. 
     Referring to  FIG. 1 , an ultrasound mask  1000  according to an embodiment may be formed to correspond to a shape of human face. In detail, the ultrasound mask may have a shape corresponding to the shape of human face to deliver cosmetic ingredients such as cosmetics or drugs formed on one surface of the ultrasound mask to the human facial skin. 
     The ultrasound mask  1000  may be provided in a predetermined size to cover a user&#39;s face and may have a predetermined elasticity in order to be adhered to the user&#39;s face. The ultrasound mask  1000  may include one surface in contact with a user&#39;s skin and the other surface opposite to the one surface, and the one surface of the ultrasound mask  1000  may be made of a material that is harmless to the human body, so that it is harmless despite being in contact with the user&#39;s skin for a long time. 
     The ultrasound mask  1000  may include an opening  1010  and/or a cutout portion  1020 . In detail, the opening  1010  may be formed in a portion corresponding to the user&#39;s eyes or mouth. The opening  1010  is a region penetrating through one surface and the other surface of the mask  1000 , and when the user wears the mask  1000 , the user&#39;s eyes and mouth may be inserted into the opening  1010 , and the region excluding the opening  1010  may be closely adhered to the user&#39;s face. 
     In addition, the cutout portion  1020  may be formed in a portion corresponding to both cheek lines, chin, and the like, which are relatively curved in order to improve adhesion between the mask  1000  and the skin. The cutout portion  1020  may have a form in which one surface and the other surface of the mask  1000  are partially cut. 
     The ultrasound mask may be attached to a human face to deliver cosmetic ingredients such as cosmetics or drug substances to a human facial region with which the mask is in contact. 
     For example, the ultrasound mask may be directly adhered to the skin of the human body, and cosmetic substances applied in advance to the skin may be easily delivered to the epidermal layer through the stratum corneum of the skin by ultrasonic waves generated from the ultrasound mask. 
     That is, the ultrasound mask forms a path through which a substance moves to the skin of the human body through ultrasonic waves, and thus, a substance to be absorbed into the skin may be easily transferred into the skin to be absorbed into the skin. 
     In detail, the mask according to the embodiment may deliver cosmetic substances or drug substances to a region of the human body that is in contact with the mask using a sonophoresis principle. 
     The sonophoresis principle is a means of delivering cosmetic ingredients or drug ingredients using ultrasonic waves. In detail, the sonophoresis principle is defined that microbubbles inside the skin are expanded by ultrasonic waves to form micro-channels in the skin so as to enable to absorb polar and non-polar particles and macromolecules within 5 μm. 
     That is, in the ultrasound mask according to the embodiment, ultrasonic waves are applied in a direction of the skin of the human body by a piezoelectric member inside the mask, and ingredients such as cosmetic substances positioned on one surface of the ultrasound mask facing the skin of the human body may pass through the stratum corneum of the skin through microchannels of the skin formed by the ultrasonic waves to be delivered to the epidermal layer. 
     Meanwhile, the ultrasound mask according to the embodiment described below relates to an ultrasound mask that may absorb ingredients such as cosmetic substances into the skin in a simple manner using a mask method, minimize the loss of ultrasonic waves to improve drug delivery efficiency, and minimize damage to electrodes inside the mask due to wearing the mask. 
     Hereinafter, Referring to  FIGS. 2 to 9 , an ultrasound mask according to an embodiment will be described in detail through an internal structure of a mask according a first embodiment. 
       FIG. 2  is a view illustrating a cross-sectional view of an ultrasound mask according to an embodiment. Referring to  FIG. 2 , the ultrasound mask according to the embodiment may include a plurality of piezoelectric members  500  disposed to be spaced apart from each other. 
     The piezoelectric member  500  may generate ultrasonic waves, and the ultrasonic waves may easily penetrate cosmetic ingredients disposed between the ultrasound mask and the skin of the human body into the skin through electrodes, wirings, and base layers serving as a specific functional layer to be described below. 
     In detail, referring to  FIGS. 3 and 4 , the plurality of piezoelectric members  500  of the ultrasound mask according to the first embodiment may be connected to each other through a plurality of wirings. In detail, a lower surface of the piezoelectric member  500  may be connected to a first wiring  210 , and an upper surface of the piezoelectric member  500  may be connected to a second wiring  220 . 
       FIG. 3  is a view for describing electrical connection between the first wiring  210  and the piezoelectric member  500  disposed on a first substrate  110  that is a lower substrate of the ultrasound mask according to the first embodiment, and  FIG. 4  is a view for describing electrical connection between the second wiring  220  and the piezoelectric member  500  disposed on a second substrate  120  that is an upper substrate of the ultrasound mask according to the first embodiment. 
     Referring to  FIG. 3 , the first wiring  210  may be disposed on one surface of the first substrate  110 . In detail, the first wiring  210  may be disposed on an upper surface of the first substrate  110 . In more detail, the first wiring  210  may be disposed inside the first substrate  110 . 
     The first wiring  210  may be disposed to extend in a first direction. The first wiring  210  may be arranged in the first direction. That is, the first wiring  210  may include a plurality of unit wirings extending in the first direction. For example, the first wiring  210  may include a plurality of unit wirings extending in a column direction, and the unit wirings may be disposed to be spaced apart from each other. 
     In detail, one end and the other end of each piezoelectric member  500  may be connected to two interconnection wirings, and the unit wirings may be defined as an assembly of interconnection wirings connected to each other. 
     In addition, the first wiring  210  may be defined as an assembly of a plurality of unit wirings extending in a column direction and spaced apart from each other. 
     In addition, referring to  FIG. 4 , the second wiring  220  may be disposed on one surface of the second substrate  120 . In detail, the second wiring  220  may be disposed on a lower surface of the second substrate  120 . In more detail, the second wiring  220  may be disposed inside the second substrate  120 . 
     The second wiring  220  may be disposed to extend in a second direction. The second wiring  220  may be arranged in a second direction. The second direction may be a different direction from the first direction. For example, the first direction and the second direction may be directions crossing each other. 
     That is, the second wiring  220  may include a plurality of unit wirings extending in the second direction. As an example, the second wiring  220  may include the plurality of unit wirings extending in a row direction, and the unit wirings may be disposed to be spaced apart from each other. 
     In detail, one end and the other end of each piezoelectric member  500  may be connected to two interconnection wirings, and the unit wirings may be defined as the assembly of the interconnection wirings connected to each other. 
     In addition, the second wiring  110  may be defined as an assembly of the plurality of unit wirings extending in a row direction and spaced apart from each other. 
     At least one of the first wiring  210  and the second wiring  220  may include a conductive material. As an example, at least one of the first wiring  210  and the second wiring  220  may include various metals. 
     In detail, at least one of the first wiring  210  and the second wiring  220  may include at least one metal of chromium (Cr), nickel (Ni), copper (Cu), aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), titanium (Ti), and alloys thereof. 
     In addition, the first wiring  210  and the second wiring  220  may have a predetermined thickness and line width. For example, the line width of the first wiring  210  and the second wiring  220  may be 50 μm to 500 μm. 
     Further, the thickness of the first wiring  210  and the second wiring  220  may have a size of about 1/10 or less of the line width. As an example, the thickness of the first wiring  210  and the second wiring  220  may be about 5 μm to 50 μm. 
     Accordingly, when the ultrasound mask is bent or folded in one direction, it is possible to prevent the wirings from being disconnected or damaged by controlling the line width and thickness of the first wiring  210  and the second wiring  220 , thereby improving the reliability of the ultrasound mask. 
     In addition, at least one of the first wiring  210  and the second wiring  220  may have stretch characteristics. In detail, the first wiring  210  and the second wiring  220  may have an elongation characteristic extending in a tensile direction. 
     For example, the first wiring  210  and the second wiring  220  may be stretched by about 10% to about 50% of the total length. 
     At least one of the first wiring  210  and the second wiring  220  may have a curved shape. In detail, at least one of the first wiring  210  and the second wiring  220  may extend while having a curvature. 
     As shown in  FIGS. 3 and 4 , the first wiring  210  may be arranged in the first direction while having a curvature, and the second wiring  220  may also be arranged in the second direction while having a curvature. 
     In the first wiring  210  and the second wiring  220 , patterns having the same curvature size may be continuous, or the first wiring  210  and the second wiring  220  may extend respectively while patterns having different curvature sizes are continuous. 
     In detail, the first wiring  210  may extend in the first direction while patterns having a curvature size (mm) of 5R to 15R are continuous, and the second wiring  220  may extend in the second direction while patterns having a curvature size (mm) of 5R to 15R are continuous. 
     As the first wiring  210  and the second wiring  220  are formed in a curved shape having a curvature, it is possible to prevent the first wiring  210  and the second wiring  220  from being deformed or damaged due to stress generated when the ultrasound mask according to the first embodiment is stretched or restored. 
     That is, when the ultrasound mask according to the first embodiment is stretched or restored, the first wiring  210  and the second wiring  220  having a shape of continuous curvature patterns are stretched or restored together like a spring, and thus, it is possible to minimize a stress effect due to stretch or restoration. 
     In addition, since the first wiring  210  extends only in the first direction and the second wiring extends only in the second direction, restrictions depending on the direction may be minimized when the ultrasound mask according to the first embodiment is stretched or restored. That is, it is possible to improve the flexibility of the ultrasound mask. 
       FIG. 5  is a view illustrating that the first substrate  110  and the second substrate  120  overlap each other. 
     Referring to  FIG. 5 , the first substrate  110  and the second substrate  120  may be disposed to overlap in upper and lower portions, and the first wiring  210  disposed on the upper surface of the first substrate  110  and the second wiring  220  disposed on the lower surface of the second substrate  120  may also be disposed to overlap each other. 
     When viewed from the lower surface of the first substrate  110  or the upper surface of the second substrate  120 , the first wiring  210  and the second wiring  220  may be formed in a mesh shape. That is, while the first wiring  210  extending in the first direction and the second wiring  220  extending in the second direction overlap each other, the first wiring  210  and the second wiring  220  may be formed in the mesh shape as a whole. 
     Hereinafter, the overall configuration of the ultrasound mask according to the first embodiment will be described in detail with reference to  FIGS. 6 and 7 . 
       FIG. 6  is a view illustrating an overall cross-sectional view taken along line B-B′ in  FIG. 5  of the ultrasound mask according to the first embodiment, and  FIG. 7  is a view illustrating an overall cross-sectional view taken along line C-C′ in  FIG. 5  of the ultrasound mask according to the first embodiment. 
     Referring to  FIGS. 6 and 7 , the ultrasound mask according to the first embodiment may include a substrate, a wiring, an electrode, a piezoelectric member, and a base layer. 
     The substrate may include the first substrate  110  and the second substrate  120 . The first substrate  110  may be the lower substrate of the ultrasound mask according to the first embodiment, and the second substrate  120  may be the upper substrate. 
     The first substrate  110  may support the first wiring  210  and a first electrode  410  disposed inside the first substrate  110 , and the second substrate  120  may support the second wiring  220  and a second electrode  420  disposed inside the substrate  120 . That is, the first substrate  110  and the second substrate  120  may be supporting substrates. 
     The second substrate  120  may be disposed on the upper surface of the first substrate  110 . The first substrate  110  and the second substrate  120  may be disposed to be spaced apart from each other. The first substrate  110  and the second substrate  120  may be disposed to be spaced apart from each other, and the piezoelectric member  500  may be disposed between the first substrate  110  and the second substrate  120 . 
     The first substrate  110  and the second substrate  120  may be flexible. In detail, the first substrate  110  and the second substrate  120  may be flexible so as to be bendable or foldable. In addition, at least one of the first substrate  110  and the second substrate  120  is closely adhered to the human face described above, and thus the substrate may be formed of a material harmless to the human body. 
     For example, the first substrate  110  and the second substrate  120  may include plastic. As an example, the first substrate  110  and the second substrate  120  may include a flexible plastic such as polyimide (PI), polyethylene terephthalate (PET), propylene glycol (PPG) polycarbonate (PC), or the like. 
     Accordingly, when the user wears the ultrasound mask on the face or the like and applies a deformation that stretches or restores the ultrasound mask according to the size and shape of the user&#39;s face, the shape of the ultrasound mask may be easily changed. 
     In addition, the first substrate  110  and the second substrate  120  may have a certain thickness. 
     For example, the first substrate  110  and the second substrate  120  may have a thickness of about 0.5 μm to about 5 μm or less. When the thicknesses of the first substrate  110  and the second substrate  120  are less than about 0.5 μm, shapes of the regions of the first substrate  110  and the second substrate  120  overlapping the components are changed by the weight of components to be disposed on the first substrate  110  and the second substrate  120 , for example, the piezoelectric member  500 , so that a problem that may affect adhesion and absorption of cosmetic ingredients may occur. 
     Accordingly, reliability of the first substrate  110  and the second substrate  120  may be deteriorated, and an alignment tolerance of components disposed on the first substrate  110  and the second substrate  120  may be increased. 
     In addition, when the thicknesses of the first substrate  110  and the second substrate  120  exceed about 5 μm, the overall thickness of the ultrasound mask  1000  according to the first embodiment may be increased. Accordingly, there is a problem that the ultrasound mask  1000  according to the first embodiment may not be efficiently varied according to the shape of the user&#39;s skin, and thus the mask  1000  does not effectively adhere to the user&#39;s skin. 
     Preferably, the first substrate  110  and the second substrate  120  may have a thickness of about 0.5 μm to about 3 μm. When the thicknesses of the first substrate  110  and the second substrate  120  satisfy the above-described range, the first substrate  110  and the second substrate  120  may be efficiently varied in a form corresponding to the user&#39;s skin and the overall thickness and weight of the ultrasound mask  1000  according to the embodiment may be reduced while maintaining reliability and alignment characteristics. 
     Meanwhile, the first substrate  110  and the second substrate  120  may have a plurality of engraved portions I and a plurality of embossed portions E. Each of the embossed portions E may be formed between the engraved portions I. 
     In detail, referring to  FIGS. 8 and 9 , a plurality of first engraved portions I 1  formed on the upper surface of the first substrate  110  may be formed on the first substrate  110 , and a plurality of second engraved portions  12  formed on the lower surface of the second substrate  120  may be formed on the second substrate  120 . 
     That is, a thickness of the first substrate  110  in a region where the first engraved portion I 1  is formed may be smaller than a thickness of the first substrate  110  in a region where the first engraved portion I 1  is not formed. 
     In addition, a thickness of the second substrate  120  in a region where the second engraved portion I 2  is formed may be smaller than a thickness of the second substrate  120  in a region where the second engraved portion I 2  is not formed. 
     The first wiring  210  and the second wiring  220  described above may be disposed on the upper surface of the first substrate  110  and the lower surface of the second substrate  120 , respectively. 
     The first wiring  210  may be disposed inside the first engraved portion I 1  of the first substrate  110 . In detail, the first wiring  210  may be formed while filling the inside of the first engraved portion I 1  formed on the upper surface of the first substrate  110 . Accordingly, the first wiring  210  may be disposed inside the first substrate  110 . 
     In addition, the second wiring  220  may be disposed inside the second engraved portion I 2  of the second substrate  120 . In detail, the second wiring  220  may be formed while filling the inside of the second engraved portion I 2  formed on the lower surface of the second substrate  120 . Accordingly, the second wiring  220  may be disposed inside the second substrate  120 . 
     As described above, since the first wiring  210  is formed to extend only in the first direction, and the second wiring  220  is formed to extend only in the second direction, in  FIG. 6  which is a view taken along line B-B′ in  FIG. 5 , only the curve-shaped second wiring  220  may be disposed between the piezoelectric members  500 , and in  FIG. 7  which is a view taken along line C-C′ in  FIG. 5 , only the curve-shaped first wiring  210  may be disposed between the piezoelectric members  500 . 
     Since the first wiring  210  and the second wiring  220  are disposed inside the first engraved portion I 1  and the second engraved portion I 2  formed in the first substrate  110  and the second substrate  120 , respectively, it is possible to prevent an increase in the thickness of the ultrasound mask due to the thicknesses of the first wiring  210  and the second wiring  220 . 
     In addition, since the first wiring  210  and the second wiring  220  are disposed while being fixed by the engraved portion inside the engraved portions, a phenomenon that the wirings are de-filmed during variable such as stretching or restoring the ultrasound mask is prevented, thereby improving the reliability of the ultrasound mask. 
     The piezoelectric member  500  may be disposed between the first substrate  110  and the second substrate  120 . That is, the piezoelectric member  500  may be disposed on the upper surface of the first substrate  110  and may be disposed under the lower surface of the second substrate  120 . 
     The piezoelectric member  500  may generate ultrasonic waves, and the ultrasonic waves generated from the piezoelectric member  500  may be moved from the first substrate  110  toward the second substrate  120 . 
     The piezoelectric member  500  may be disposed between the first substrate  110  and the second substrate  120  in plural. In detail, the piezoelectric members  500  may be disposed to be spaced apart from each other between the first and second substrates  110  and  120 , and accordingly, the ultrasonic waves may be generated over the entire area of the ultrasound mask. 
     Meanwhile, the piezoelectric members  500  may be disposed to be spaced apart at the same or a similar distance between the first substrate  110  and the second substrate  120 . 
     Alternatively, the piezoelectric members  500  may be disposed to be spaced apart from each other at different distances between the first substrate  110  and the second substrate  120 . For example, when the ultrasound mask is put on the skin of the human body, the separation distance of the piezoelectric member  500  may vary depending on a size at which the ultrasound mask is bent. 
     For example, when the ultrasound mask is put on the skin of the human body, a bent region for each region may vary depending on the shape and size of the face. In this case, the distance of the piezoelectric member  500  may be increased in the region where the ultrasound mask is bent, and accordingly, the distance of the piezoelectric member  500  is decreased in a region that is largely bent, so that it is possible to compensate that the distance of the piezoelectric element is varied for each region when the ultrasound mask is put on the skin. 
     Meanwhile, the piezoelectric member  500  may include a rigid material. 
     The piezoelectric member  500  may include various piezoelectric materials. For example, the piezoelectric member  500  may include single crystal ceramics, polycrystalline ceramics, a polymer material, a thin film material, or a composite material in which the polycrystalline material and the polymer material are composited. 
     A piezoelectric material of the single crystal ceramics may include α-AlPO4, α-SiO2, LiTiO3, LiNbO3, SrxBayNb2O3, Pb5-Ge3O11, Tb2(MnO4)3, Li2B4O7, CdS, ZnO, Bi12SiO20, or Bi12GeO20. 
     In addition, a piezoelectric material of the polycrystalline ceramics may include PZT-based, PT-based, PZT-Complex Perovskite-based, or BaTiO3. 
     In addition, a piezoelectric material of the polymer material may include PVDF, P(VDF-TrFe), P(VDFTeFE), or TGS. 
     In addition, a piezoelectric material of the thin film material may include ZnO, CdS, or AlN. 
     In addition, a piezoelectric material of the composite material may include PZT-PVDF, PZT-Silicon Rubber, PZT-Epoxy, PZT-foaming polymer, or PZT-foaming urethane. 
     The plurality of piezoelectric members  500  may include at least one piezoelectric material among the single crystal ceramics, the polycrystalline ceramics, the polymer material, the thin film material, or the composite material in which the polycrystalline material and the polymer material are composited. 
     The plurality of piezoelectric members  500  may include the same piezoelectric material or may include different piezoelectric materials. 
     For example, the ultrasound mask according to the embodiment may include a piezoelectric material that generates low-frequency or medium-frequency ultrasonic waves. In detail, the ultrasound mask according to the embodiment may include a piezoelectric material that generates ultrasonic waves of a low frequency having a 20 kHz to 100 kHz band and/or a medium frequency having a 100 kHz to 1 MHz band that are optimized for beauty. 
     As an example, the ultrasound mask according to the embodiment may include single crystal or polycrystalline ceramics including ceramic. 
     The waveform of the ultrasonic wave applied from the piezoelectric member  500  is not limited and may include a sine waveform, a sawtooth waveform, or a pulse waveform. 
     In addition, ultrasonic waves generated from the piezoelectric member  500  may be applied as at least one of a transverse wave and a longitudinal wave. In detail, the ultrasonic waves generated from the piezoelectric member  500  may be applied as a single wave of a transverse wave, a single wave of a longitudinal wave, or a plurality of waves applied with both transverse wave and longitudinal wave. 
     That is, the piezoelectric member according to the embodiment may generate the ultrasonic waves in a single or multiple resonance modes. 
     A thickness of the piezoelectric member  500  may be about 600 μm or less. In detail, the thickness of the piezoelectric member  500  may be about 500 μm or less. Preferably, the thickness of the piezoelectric member  500  may be about 300 μm or less. It is preferable that the thickness of the piezoelectric member  500  satisfies the above-described range in consideration of the variable characteristics of the ultrasound mask  1000 . 
     The piezoelectric member  500  may have various shapes. For example, the piezoelectric member  500  may have a polygonal column shape in which lower and upper surfaces are polygonal, and the lower and upper surfaces may have a circular column shape. In addition, one surface of the lower and upper surfaces of the piezoelectric member  500  may be a polygon and the other surface may have a pillar shape. As an example, an area of at least one of the lower surface and the upper surface of the piezoelectric member  500  may be about 100 mm 2  or less. 
     As described above, the piezoelectric member  500  may have various pillar shapes, and intensity of ultrasonic vibration and an oscillation direction of vibration generated according to the pillar shape may be controlled. In addition, the intensity of vibration transmitted to the user&#39;s skin may be adjusted according to a size, arrangement interval, arrangement density, and the like of the piezoelectric member  500 . 
     The piezoelectric member  500  may generate various waves. For example, the piezoelectric member  500  may generate at least one wave of a transverse wave in which a traveling direction of wave and a vibration direction of medium are perpendicular, and a longitudinal wave in which the traveling direction of wave and the vibration direction of medium are the same. In addition, the piezoelectric member  500  may multiple-resonate. 
     For example, the piezoelectric member  500  may include at least one via hole and may multiple-resonate by the formed via holes. In this case, an upper area of the via holes may be about 10% to about 45% of an area of the upper surface of the piezoelectric member  500  for multiple resonance. 
     In addition, when the piezoelectric member  500  multiple-resonates by the via holes, the number of multiple resonance frequency regions may correspond to the number of the via holes. That is, the piezoelectric member  500  may emit wavelengths of various frequency ranges as the number of the via holes increases in a set number range of via holes. 
     An electrode may be disposed on the lower surface and the upper surface of the piezoelectric member  500 , respectively. In detail, the first electrode  410  may be disposed on the lower surface of the piezoelectric member  500 , and the second electrode  420  may be disposed on the upper surface of the piezoelectric member  500 . 
     That is, the first electrode  410  may be disposed on the upper surface of the first substrate  110 , and the second electrode  420  may be disposed under the lower surface of the second substrate  120 . 
     The first electrode  410  and the second electrode  420  may be in contact with the piezoelectric member  500 . In detail, the first electrode  410  may be disposed in direct contact with the lower surface of the piezoelectric member  500 , and the second electrode  420  may be disposed in direct contact with the upper surface of the piezoelectric member  500 . 
     Accordingly, the first electrode  410  and the second electrode  420  may be disposed on both surfaces of the piezoelectric member  500 , respectively, and a voltage may be applied to the piezoelectric member by the first electrode  410  and the second electrode  420  to vibrate the piezoelectric member. 
     In detail, a voltage applied from the outside of the ultrasound mask is transmitted to the first electrode  410  and the second electrode  420  through the first wiring  210  and the second wiring  220 , and accordingly, the voltage is applied to the piezoelectric member  500 , so that the piezoelectric member  500  may be vibrated to generate ultrasonic waves having a specific frequency range. 
     The first electrode  410  may be disposed on the entire surface of the lower surface of the piezoelectric member  500 . In addition, the second electrode  420  may be disposed on the entire surface of the upper surface of the piezoelectric member  500 . In this case, the entire surface of the lower surface and the upper surface of the piezoelectric member may be defined as a region including an error during the process. 
     At least one of the first electrode  410  and the second electrode  420  may include various metals. For example, at least one of the first electrode  410  and the second electrode  420  may include at least one metal of chromium (Cr), nickel (Ni), copper (Cu), aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), titanium (Ti), and alloys thereof. 
     Alternatively, at least one of the first electrode  410  and the second electrode  420  may be formed in a mesh shape. In detail, at least one of the first electrode  410  and the second electrode  420  may include a plurality of sub-electrodes, and the sub-electrodes may be disposed to cross each other in the mesh shape. 
     In detail, at least one of the first electrode  410  and the second electrode  420  may include a mesh line LA and a mesh opening OA between the mesh lines LA by the plurality of sub-electrodes crossing each other in the mesh shape. 
     A line width of the mesh line LA may be about 0.1 μm to about 10 μm. A mesh line having a line width of less than about 0.1 μm of the mesh line LA may not be possible in a manufacturing process, and when the line width exceeds about 10 μm, an electrode pattern may be visually recognized from the outside and visibility may be reduced. In detail, the line width of the mesh line LA may be about 1 μm to about 5 μm. In more detail, the line width of the mesh line LA may be about 1.5 μm to about 3 μm. 
     In addition, the thickness of the mesh line LA may be about 100 nm to about 1000 nm. When the thickness of the mesh line is less than about 100 nm, an electrode resistance may increase and electrical characteristics may be deteriorated. When the thickness of the mesh line exceeds about 1000 nm, the overall thickness of the ultrasound mask may increase and process efficiency may be deteriorated. In detail, the thickness of the mesh line LA may be about 150 nm to about 500 nm. In more detail, the thickness of the mesh line LA may be about 180 nm to about 200 nm. 
     In addition, the mesh opening may be formed in various shapes. For example, the mesh opening OA may have various shapes such as a square shape, a diamond shape, a polygonal shape of pentagonal shape and hexagonal shape, a circular shape, or the like. In addition, the mesh opening may be formed in a regular shape or a random shape. 
     The electrode and the wiring may be adhered to each other. In detail, the electrode and the wiring may be adhered to each other through a conductive adhesive layer. 
     In detail, the first wiring  210  and the first electrode  410  may be adhered through a first adhesive layer  310 , and the second wiring  210  and the second electrode  420  may be adhered through a second adhesive layer  320 . 
     The first adhesive layer  310  and the second adhesive layer  320  may have conductivity. In detail, the first adhesive layer  310  and the second adhesive layer  320  may be conductive pastes. For example, the first adhesive layer  310  and the second adhesive layer  320  may include silver (Ag) paste. 
     Accordingly, the first wiring  210  and the first electrode  410  and the second wiring  220  and the second electrode  420  may be electrically connected to by the first adhesive layer  310  and the second adhesive layer  320 . 
     Meanwhile, the first adhesive layer  310  and the second adhesive layer  320  may be formed to have the same and similar thickness. Alternatively, the first adhesive layer  310  and the second adhesive layer  320  may be formed to have different thicknesses. 
     In detail, a thickness of the first adhesive layer  310  may be greater than a thickness of the second adhesive layer  320 . That is, the thickness of the first adhesive layer  310  disposed further from the skin may be greater than the thickness of the second adhesive layer  320 . 
     Accordingly, ultrasonic waves generated from the piezoelectric member  500  and moved in a opposite direction of the skin may be reflected by the first adhesive layer  310  to transmit in a direction of the skin by making a thickness of the first adhesive layer  310  different from a thickness of the second adhesive layer  320 , thereby minimizing the loss of ultrasonic waves. 
     Meanwhile, base layers for easily transmitting ultrasonic waves to the skin may be disposed on outer surfaces of the first substrate  110  and the second substrate  120 , respectively. 
     The above-described substrates, wirings, electrodes, and piezoelectric members may be disposed between the base layers, that is, the base layers may be support layers supporting a plurality of components. 
     For example, when it is defined that a position where the second substrate  120  is disposed is a place close to the skin of the human body, and a position where the first substrate  110  is disposed is a place far from the skin of the human body, a first base layer  610  in which the ultrasonic waves generated from the piezoelectric member  500  is reflected so that the ultrasonic waves are transmitted in the direction of the skin of the human body may be disposed on an outer surface of the first substrate  110 , that is, the lower surface of the first substrate  110 . 
     A second base layer  620  in which the ultrasonic waves generated from the piezoelectric member  500  is reflected so that the ultrasonic waves are transmitted in the direction of the skin of the human body may be disposed on an outer surface of the second substrate  120 , that is, the upper surface of the second substrate  120 . That is, the second base layer  620  may be defined as a layer that is in direct contact with the skin of the human body to transmit the ultrasonic waves. 
     In detail, the second base layer  620  may be disposed on the upper surface of the second substrate  120 . The second base layer  620  may include a matching layer. 
     The second base layer  620  may reduce energy loss due to reflection of an ultrasonic signal due to a difference in acoustic impedance between the piezoelectric member and the object, that is, the skin of the human body. To this end, the second base layer  620  is formed of a material having an acoustic impedance corresponding to between the acoustic impedance of the piezoelectric member and the acoustic impedance of the skin of the human body, and accordingly, energy loss of the ultrasonic signal may be minimized by configuring a plurality of acoustic matching layers having an acoustic impedance gradually decreasing from the second base layer  620  adjacent to the piezoelectric element. 
     As an example, the second base layer  620  may include silicon (Si). For example, the second base layer  620  may include silicon or a silicon compound. In addition, a thickness of the second base layer  620  may be about 1 mm or less. In detail, a thickness of the matching layer may be about 300 μm to about 1 mm. 
     The thickness of the second base layer  620  may be changed depending on the frequency of ultrasonic waves generated from the piezoelectric member  500 . 
     In detail, the thickness of the second base layer  620  may be defined as a size of λ/4 or more of the wavelength at the wavelength λ calculated by the following equation. 
       Sound velocity of the second base layer=Frequency generated from the piezoelectric member*wavelength (λ)  [Equation]
 
     That is, the thickness of the second base layer  620  may be formed so as to have a size of about 25% or more of the size of the wavelength calculated by the equation. 
     For example, when the second base layer  620  includes silicon (Si), a wavelength value may be determined depending on a size of the frequency region generated in the piezoelectric member, and the thickness of the second base layer  620  may be formed in a size of about 25% or more of the size of the wavelength. 
     Accordingly, when ultrasonic waves generated from the piezoelectric member are transmitted to the human skin by the matching layer, the loss of ultrasonic waves may be minimized. 
     The first base layer  610  may be disposed on the lower surface of the first substrate  110 . The first base layer  610  may include a backing layer. 
     The first base layer  610  may reflect the ultrasonic waves moving in a direction of the first substrate that is a direction opposite to the skin of the human body among the ultrasonic waves generated from the piezoelectric member  500  and moving in the direction of the skin of the human body. That is, the first base layer  610  may be a reflective layer that reflects the ultrasonic waves. 
     The backing layer may include a material the same as or similar to that of the matching layer. For example, the backing layer may include silicon (Si). 
     The backing layer may be formed with a thickness different from that of the matching layer. In detail, the backing layer may be formed to have a thickness the same as or smaller than that of the matching layer. 
     In addition, the first base layer  610  may have an air layer formed therein to easily reflect the ultrasonic waves. That is, a plurality of pores may be formed inside the first base layer  610  to reflect the ultrasonic waves incident into the first base layer  610  toward the second base layer  620 . 
     In addition, the first base layer  610  may be formed in a shape different from that of the second base layer  620 . In detail, the first base layer  610  may include a groove formed in a region corresponding to the piezoelectric member  500 . Accordingly, the ultrasonic waves incident into the first base layer  610  may be reflected toward the second base layer  620  by the air layer formed inside the groove. 
     The first base layer  610  and the second base layer  620  may be formed to have a size the same as or similar to that of the first base layer  110  and the second base layer  120 . That is, the first base layer  610  and the second base layer  620  may be disposed while covering the plurality of piezoelectric members. 
     That is, the first base layer  610  and the second base layer  620  are formed to be greater than an area of the piezoelectric member, so that ultrasonic waves radiated from the piezoelectric member may be effectively transmitted in the direction of the skin of the human body. 
     Accordingly, the ultrasonic waves generated radially from the piezoelectric material may be easily transmitted in the direction of the skin of the human body by the first base layer and the second base layer. 
     Meanwhile, a protective layer  150  may be disposed between the first substrate  110  and the second substrate  120 . The protective layer  150  may include a material that is the same as or similar to that of at least one of the first base layer  610  and the second base layer  620 . For example, the protective layer  150  may include silicon or a silicon-based compound. 
     The first wiring  210  and the second wiring  220  may be in contact with the protective layer  150 . In detail, a part of the first wiring  210  and the second wiring  220  may be in contact with the protective layer  150 . 
     In detail, an interconnection wiring of the first wiring  210  and the second wiring  220  connecting the piezoelectric members  500  may be in contact with the protective layer  150 . 
     That is, the interconnection wirings of the first wiring  210  and the second wiring  220  may be disposed in the engraved portions of the first substrate  110  and the second substrate  120 , respectively, an exposed surface may be formed in which one surface of the interconnection wiring is exposed to the outside, and the exposed surface of the interconnection wiring may be in contact with the protective layer  150 . 
     The protective layer  150  prevents damage from external impacts or impurities to the piezoelectric member  500 , the electrodes, the wirings, and the like between the first substrate  110  and the second substrate  120 , thereby improving the reliability of the ultrasound mask. 
     In addition, as the protective layer  150  is disposed while covering the interconnection wirings of the first and second wirings exposed to the outside, oxidation of the wirings including the metal may be prevented, thereby improving reliability. 
     The ultrasound mask according to the first embodiment may easily transfer a material into the skin of the human body using ultrasonic waves. 
     In detail, cosmetic substances such as cosmetics may be easily delivered according to a position, shape, and size of an object to be worn by a user through a rigid piezoelectric member, a flexible substrate, and a wiring. 
     In addition, when the user wears the ultrasound mask through the substrate and the wiring that may be stretched and restored, it is possible to prevent an electrode from being damaged due to deformation of the ultrasound mask. 
     In addition, it is possible to minimize the loss of ultrasonic waves generated during transmission by controlling the directionality of the ultrasonic waves generated from the piezoelectric member by the matching layer and the backing layer. 
     In addition, it is possible to minimize the loss of ultrasonic waves generated during transmission by controlling thicknesses of the matching layer and the backing layer and controlling the movement of ultrasonic waves according to the frequency band of the ultrasonic waves generated from the piezoelectric member. 
     In addition, when the ultrasound mask is stretched or restored, the first wiring  210  and the second wiring  220  having a shape of continuous curvature patterns are stretched or restored together like a spring, so the stress effect due to stretch or restoration may be minimized. 
     In addition, since the first wiring  210  extends only in the first direction and the second wiring extends only in the second direction, when the ultrasound mask according to the first embodiment is stretched or restored, the restriction depending on the direction may be minimized. That is, the flexibility of the ultrasound mask may be improved. 
     Hereinafter, an ultrasound mask according to a second embodiment will be described with reference to  FIGS. 10 to 14 . In the description of the ultrasound mask according to the second embodiment, a description of the same and similar description as the ultrasound mask according to the first embodiment described above will be omitted. In addition, in the description of the ultrasound mask according to the second embodiment, the same reference numerals are given to the same components as those of the ultrasound mask according to the first embodiment described above. 
     Referring to  FIGS. 10 to 14 , the ultrasound mask according to the second embodiment may have different directions in which the first and second wirings extend from the ultrasound mask according to the first embodiment described above. 
     In detail, referring to  FIG. 10 , the first wiring  210  may be disposed on the upper surface of the first substrate  110 . That is, the first wiring  210  may be disposed inside the first substrate  110 . In addition, the first wiring  210  may be arranged in a first direction and a second direction that cross each other. Accordingly, the first wiring  210  may be arranged in two different directions. 
     That is, the first wiring  210  may include a plurality of unit wirings extending in the first direction and a plurality of unit wirings extending in the second direction. For example, the first wiring  210  may include a plurality of unit wirings extending in a row direction and a plurality of unit wirings extending in a column direction, and the unit wirings may be disposed to be spaced apart from each other. 
     In addition, referring to  FIG. 11 , the second wiring  220  may be disposed on the lower surface of the second substrate  120 . That is, the second wiring  220  may be disposed inside the second substrate  120 . The second wiring  220  may be formed to extend in the first direction and the second direction. That is, the second wiring  220  may be disposed to extend in two different directions, and the direction in which the second wiring  220  extends may be similar to that of the first wiring  210 . 
     That is, the second wiring  220  may include a plurality of unit wirings extending in the first direction and a plurality of unit wirings extending in the second direction. As an example, the second wiring  220  may include a plurality of unit wirings extending in the row direction and a plurality of unit wirings extending in the column direction, and the unit wirings may be disposed to be spaced apart from each other. 
     That is, when viewed from the lower surface of the first substrate  110 , the first wiring  210  may be formed in a mesh shape, and when viewed from the upper surface of the second substrate  120 , the second wiring  220  may be formed in the mesh shape, 
       FIG. 12  is a view illustrating that the first substrate  110  and the second substrate  120  overlap each other. 
     Referring to  FIG. 12 , the first substrate  110  and the second substrate  120  are disposed to overlap in upper and lower portions, and the first wiring  210  and the first wiring  210  disposed on the upper surface of the first substrate  110  and the second wiring  220  disposed on the lower surface of the second substrate  120  may also be disposed to overlap each other. 
     When viewed from the lower surface of the first substrate  110  or the upper surface of the second substrate  120 , the first wiring  210  and the second wiring  220  may be formed in the mesh shape. That is, while the first wiring  210  extending in the first direction and the second wiring  220  extending in the second direction overlap each other, the first wiring  210  and the second wiring  220  may be formed in the mesh shape as a whole. 
     In the ultrasound mask according to the second embodiment, the first wiring may be formed to extend in two directions, and the second wiring may also be arranged in two directions. 
     Accordingly, both the first wiring  210  and the second wiring  220  may be arranged in two different directions in the first direction and the second direction. 
     Therefore, in  FIG. 13  which is a view taken along line D-D′ in  FIG. 12 , both the first wiring  210  and the second wiring  220  having the curved shape are disposed between the piezoelectric members  500 , and in  FIG. 14  which is a view taken along line E-E′ in  FIG. 12 , both the first wiring  210  and the second wiring  220  having the curved shape are disposed between the piezoelectric members  500 . 
     Accordingly, even though a short circuit occurs in the first wiring or the second wiring in the row direction in one piezoelectric member  500 , the first wiring or the second wiring in the column direction is energized, and even though a short circuit occurs in the first wiring or the second wiring in the column direction, the first wiring or the second wiring in the row direction is energized, so that deterioration of characteristics due to the short circuit may be prevented. 
     As described above, the ultrasound mask may be varied to fit the shape of the skin of the human body, and a short circuit may be generated in the wiring due to the stress generated in the changing process. 
     Since the ultrasound mask according to the second embodiment is arranged to extend wiring in both the row direction and the column direction, even though the wiring is shorted in one direction, it is possible to prevent an overall short circuit by the wiring extending in the other direction, and thus electrical characteristics and reliability of an ultrasonic element may be improved. 
     Hereinafter, an ultrasound mask according to a third embodiment will be described with reference to  FIGS. 15 to 19 . In the description of the ultrasound mask according to the third embodiment, a description of the same and similar description as the ultrasound mask according to the first and second embodiments described above will be omitted. In addition, in the description of the ultrasound mask according to the second embodiment, the same reference numerals are given to the same components as those of the ultrasound mask according to the first and second embodiments described above. 
     Referring to  FIGS. 15 to 19 , the ultrasound mask according to the third embodiment may have different directions of the first and second wirings from the ultrasound masks according to the first and second embodiments described above. 
     In detail, referring to  FIG. 15 , the first wiring  210  may be disposed on the upper surface of the first substrate  110 . That is, the first wiring  210  may be disposed inside the first substrate  110 . In addition, the first wiring  210  may be arranged only in the first direction. 
     That is, the first wiring  210  may include a plurality of unit wirings extending in the first direction. As an example, the first wiring  210  may include a plurality of unit wirings extending in a column direction, and the unit wirings may be disposed to be spaced apart from each other. 
     In addition, referring to  FIG. 16 , the second wiring  220  may be disposed on the lower surface of the second substrate  120 . That is, the second wiring  220  may be disposed inside the second substrate  120 . The second wiring  220  may be arranged in the first direction and the second direction. 
     That is, the second wiring  220  may include a plurality of unit wirings extending in the first direction and a plurality of unit wirings extending in the second direction. As an example, the second wiring  220  may include a plurality of unit wirings extending in the row direction and a plurality of unit wirings extending in the column direction, and the unit wirings may be disposed to be spaced apart from each other. 
     That is, a shape of the first wiring  210  when viewed from the lower surface of the first substrate  110  and a shape of the second wiring  220  when viewed from the upper surface of the second substrate  120  may be different from each other. 
       FIGS. 15 and 16  illustrate that the first wiring extends in one direction and the second wiring is arranged in two directions, but the embodiment is not limited thereto, and conversely, the first wiring may be arranged in two directions, and the second wirings may be arranged in one direction. 
       FIG. 17  is a view illustrating that the first substrate  110  and the second substrate  120  overlap each other. 
     Referring to  FIG. 17 , the first substrate  110  and the second substrate  120  are disposed to overlap in upper and lower portions, and the first wiring  210  and the first wiring  210  disposed on the upper surface of the first substrate  110  and the second wiring  220  disposed on the lower surface of the second substrate  120  may also be disposed to overlap each other. 
     When viewed from the lower surface of the first substrate  110  or the upper surface of the second substrate  120 , the first wiring  210  and the second wiring  220  may be formed in the mesh shape. That is, while the first wiring  210  extending in the first direction and the second wiring  220  extending in the second direction overlap each other, the first wiring  210  and the second wiring  220  may be formed in the mesh shape as a whole. 
     In this case, since the first wiring extends only in the column direction and the second wiring extends in the row and column directions, when viewed from the lower surface of the first substrate  110  or the upper surface of the second substrate  120 , a thickness of the wiring in the column direction may appear greater than a thickness of the wiring in the row direction. 
     In the ultrasound mask according to the third embodiment, the first wiring may be arranged in one direction, and the second wiring may be arranged in two directions. 
     Accordingly, since one wiring of the first wiring  210  and the second wiring  220  extends in only one direction and the other wiring extends in two directions, even though a short circuit occurs in the first wiring or the second wiring in the row direction in one piezoelectric member  500 , the first wiring or the second wiring in the column direction is energized, and the first wiring or the second wiring in the column direction is energized, and even though a short circuit occurs in the first wiring or the second wiring in the column direction, the first wiring or the second wiring in the row direction is energized, so that deterioration of characteristics due to the short circuit may be prevented. 
     As described above, the ultrasound mask may be varied to fit the shape of the skin of the human body, and a short circuit may be generated in the wiring due to the stress generated in the changing process. 
     Since the ultrasound mask according to the third embodiment is arranged to extend wiring in both the row direction and the column direction, even though the wiring is shorted in one direction, it is possible to prevent an overall short circuit by the wiring extending in the other direction, and thus electrical characteristics and reliability of an ultrasonic element. 
     In addition, since one wiring of the first wiring  210  and the second wiring  220  extends only in one direction and the other wiring extends in two directions, when the ultrasound mask according to the third embodiment is stretched or restored, the restriction depending on the direction may be minimized. That is, the flexibility of the ultrasound mask may be improved. 
     Hereinafter, ultrasound masks according to fourth to sixth embodiments will be described with reference to  FIGS. 20 to 22 . In the description of the ultrasound masks according to the fourth to sixth embodiments, a description of the same and similar description as the ultrasound mask according to the first to third embodiments described above will be omitted. In addition, in the description of the ultrasound masks according to the fourth to sixth embodiments, the same reference numerals are given to the same components as the ultrasound masks according to the first to third embodiments described above. 
     Referring to  FIGS. 20 to 22 , in the ultrasound masks according to the fourth to sixth embodiments, a metal layer and a cover layer may be disposed on a lower surface of the first base layer  610  or an upper surface of the second base layer  620  or the lower surface of the first base layer  610  and the upper surface of the second base layer  620 . 
     In detail, referring to  FIGS. 20 and 21 , in the ultrasound masks according to the fourth and fifth embodiments, a metal layer  710  may be disposed on the lower surface of the first base layer  610  or the upper surface of the second base layer  620 , and a cover layer  720  may be disposed below or above the metal layer. 
     In detail, referring to  FIG. 20 , in the ultrasound mask according to the fourth embodiment, the metal layer  710  may be disposed on the lower surface of the first base layer  610 , and the cover layer  720  may be disposed on a lower surface of the metal layer  710 . 
     In addition, referring to  FIG. 21 , in the ultrasound mask according to the fifth embodiment, the metal layer  710  may be disposed on the upper surface of the second base layer  620 , and the cover layer  720  may be disposed on the top surface of the metal layer  710 . 
     In addition, referring to  FIG. 22 , in the ultrasound mask according to the sixth embodiment, a first metal layer  711  may be disposed on the lower surface of the first base layer  610 , and a first cover layer  721  may be disposed on a lower surface of the first metal layer  711 . In addition, a second metal layer  712  may be disposed on the upper surface of the second base layer  620 , and a second cover layer  722  may be disposed on a top surface of the second metal layer  712 . 
     The metal layer  710  may have a certain elongation characteristic to vary the ultrasound mask. In addition, the cover layer  720  may include a material the same as or similar to that of the substrate or the protective layer. That is, the cover layer  720  may include silicon (Si). 
     The metal layer  710  may be disposed on the outermost surface of the ultrasound mask according to the embodiment to block the inflow of moisture and air that may penetrate from the outside. Accordingly, it is possible to prevent the electrodes and the piezoelectric member therein from being oxidized by the inflow of moisture and air into the ultrasound mask, and accordingly, it is possible to improve the reliability of the ultrasound mask. That is, the metal layer  710  may improve moisture permeability and durability of the ultrasound mask. 
     In addition, the cover layer  720  may be disposed on an outer surface of the metal layer  710  to prevent the metal layer  710  exposed to the outside from being corroded by reaction with air. 
     In addition, the metal layer may block the piezoelectric member, the electrode, or the wiring from being visually recognized from the outside, thereby improving the appearance of the ultrasound mask. 
     As previously explained, the piezoelectric member  500  may have multiple resonance. That is, the piezoelectric member  500  may oscillate at least three or more ultrasonic waves having different frequencies. In detail, the piezoelectric member  500  may oscillate at least three or more ultrasonic waves having different frequencies and oscillating in a flexion mode. 
     Referring to  FIGS. 23 and 26 , the piezoelectric member  500  may have a multilayer structure. In detail, the piezoelectric member  500  may be formed in a multi-layered structure including a first layer  510  and a second layer  520 . 
     The first layer  510  may be positioned in a region facing the skin and may be in contact with the second electrode  420 , and the second layer  520  may be in contact with the first electrode  410 . 
     The first layer  510  may include a metal material. In detail, the first layer  510  may include at least one of aluminum, stainless steel (SUS), and brass. The first layer  510  may have elasticity. 
     In addition, the second layer  520  may include a piezoelectric material. In detail, the piezoelectric member may include a ceramic piezoelectric material such as single crystal ceramics or polycrystalline ceramics. 
     A piezoelectric material of the single crystal ceramics may include α-AlPO4, α-SiO2, LiTiO3, LiNbO3, SrxBayNb2O3, Pb5-Ge3O11, Tb2(MnO4)3, Li2B4O7, CdS, ZnO, Bi12SiO20, or Bi12GeO20. 
     In addition, a piezoelectric material of the polycrystalline ceramics may include PZT-based, PT-based, PZT-Complex Perovskite-based, or BaTiO3. 
     The plurality of piezoelectric members  500  may include at least one piezoelectric material among the single crystal ceramics and the polycrystalline ceramics. As an example, the piezoelectric member  500  may include a piezoelectric material of PZT-based polycrystalline ceramics. 
     The first layer  510  and the second layer  520  may be formed in a circular shape. In detail, the first layer  510  and the second layer  520  may be formed in a cylindrical shape with an outer diameter greater than a height. In addition, at least one of the first layer  510  and the second layer  520  may be formed in a ring shape in which a through-hole is formed inside a circular shape. That is, the through-hole may be formed in at least one of the first layer  510  and the second layer  520 . 
     In other words, the first layer  510  and the second layer  520  may be formed in the circular shape, and at least one layer is formed with the through-hole, so that the first layer  510  and the second layer  520  may be formed with an outer diameter and/or an inner diameter and thickness. 
     The first layer  510  and the second layer  520  may implement multiple resonance in which the piezoelectric member  500  oscillates in at least three or more flexion modes by limiting the outer diameter, inner diameter, and thickness to a specific range. 
     Referring to  FIG. 26 , in the piezoelectric member  500 , the first layer  510  and the second layer  520  may be formed in various shapes according to the outer diameter, the inner diameter, and the thickness. 
     Referring to  FIG. 26A , in the piezoelectric member  500 , the first layer  510  and the second layer  520  may have the same outer diameter, and a through-hole may be formed in the second layer  520 . Accordingly, a frequency of the flexion mode may be formed in outer diameter portions of the first layer  510  and the second layer  520 , a frequency that is in the flexion mode and has a different magnitude may be formed in the through-hole of the second layer  520 , and a frequency that has a different magnitude and is in a flexion mode mixed with flexion rather than a pure thickness mode may be formed in the second layer  520 . 
     Referring to  FIG. 26B , in the piezoelectric member  500 , the first layer  510  and the second layer  520  may have different outer diameters, and the through-hole may be formed in the second layer  520 . Accordingly, a frequency of the flexion mode may be formed in the outer diameter portion of the first layer  510 , a frequency that is in the flexion mode and has a different magnitude may be formed in the outer diameter portion of the second layer  520 , and a frequency that is in the flexion mode and has a different magnitude may be formed in the through-hole of the second layer  520 . 
     Referring to  FIG. 26C , in the piezoelectric member  500 , the first layer  510  and the second layer  520  may have different outer diameters, and the through-hole may be formed in each of the first layer  510  and the second layer  520 . Accordingly, a frequency of the flexion mode may be formed in the outer diameter portion of the first layer  510  and the second layer  520 , a frequency that is in the flexion mode and has a different magnitude may be formed in in the outer diameter portion of the first layer  510 , and a frequency that is in the flexion mode and has a different magnitude may be formed in the through-hole of the second layer  520 . 
     That is, the piezoelectric member may oscillate at least three frequencies having different sizes while having the flexion mode by controlling the outer diameter, inner diameter, and thickness of the first layer  510  and the second layer  520 . 
     In detail, when an electric field is applied to the piezoelectric member  500 , the second layer  520  of the piezoelectric member  500 , that is, the piezoelectric material expands or contracts in a longitudinal direction, and the first layer  510  causes a vertical flexion displacement according to the contraction and expansion of the second layer  520 . 
     That is, the piezoelectric member  500  may oscillate ultrasonic waves in a flexion mode in which an area resonance mode and a thickness resonance mode are combined. 
     As described above, in case of the thickness mode, it is advantageous to transmit ultrasound in the skin direction, but there is a problem due to an increase in thickness, and in case of the area resonance mode, the thickness problem may be solved, but it is difficult to transmit the ultrasound in the skin direction. 
     Accordingly, the piezoelectric member of the ultrasound mask according to the embodiment may easily transmit the ultrasound in the skin direction without the problem in thickness due to the piezoelectric member oscillating in the flexion mode. 
     In addition, the piezoelectric member  500  may perform multiple resonance. In detail, the piezoelectric member  500  may oscillate at least three or more frequencies having different sizes. In more detail, the piezoelectric member  500  may oscillate at least three or more frequencies having different sizes oscillating in the flexion mode. 
     The piezoelectric member  500  may generate a center frequency and may generate at least two or more frequencies having different sizes before and after the center frequency. For example, the piezoelectric member  500  may generate two or more frequencies having different sizes in a range of about 150 kHz before and after the center frequency. For example, the piezoelectric member  500  may have a center frequency of about 200 kHz to about 400 kHz and may generate two or more frequencies having different sizes in a range of about 150 kHz before and after the center frequency. 
     For example, the piezoelectric member  500  may oscillate a center frequency of 232 kHz and may oscillate frequencies of 115 kHz and 357 kHz, which are the vicinity of the center frequency. That is, the piezoelectric member  500  may oscillate a first frequency higher and a second frequency lower than the center frequency in the vicinity of the center frequency, and at this time, the center frequency and the first and second frequencies may oscillate in the flexion mode. 
     Therefore, the user may select a desired frequency level to use the ultrasound mask. In detail, according to the user&#39;s skin environment, a high-frequency ultrasound may be used for a thin-skinned user, and a low-frequency ultrasound may be used for a thick-skinned user. 
     Accordingly, since users having different skin environments and conditions may select a frequency suitable for the user to use the ultrasound mask, the efficiency of the ultrasound mask may be improved. 
     Meanwhile, in order for the piezoelectric member  500  to oscillate in the flexion mode and to perform multiple resonance, sizes of the inner diameter, outer diameter, and thickness of the first layer  510  and the second layer  520  constituting the piezoelectric member  500  may be controlled in a certain size range. 
     In detail, a thickness t 1  of the first layer  510  and a thickness t 2  of the second layer  520  may be about 200 μm to 1500 μm. Forming the thickness t 1  of the first layer  510  and the thickness t 2  of the second layer  520  to be less than about 200 μm is difficult to implement in a process, and when the thickness t 1  of the first layer  510  and the thickness t 2  of the second layer  520  are formed to exceed about 1500 μm, the thickness of the piezoelectric member  500  is increased, thereby increasing the overall thickness of the ultrasound mask. 
     In addition, the thickness t 1  of the first layer may have a thickness of 80% to 120% of the thickness t 2  of the second layer. That is, the thickness t 1  of the first layer  510  and the thickness t 2  of the second layer are the same as each other, or, a thickness of one of the first layer  510  and the second layer  520  may be greater. 
     In this case, when the thickness t 1  of the first layer is less than 80% of the thickness t 2  of the second layer, or the thickness t 1  of the first layer exceeds 120% of the thickness t 2  of the second layer, the frequency of the ultrasonic waves generated from the piezoelectric member  500  is increased. That is, ultrasonic waves having frequencies that are not suitable for cosmetic purposes may be generated from the ultrasound mask, and the number of frequencies oscillating in the flexion mode may be less than three. 
     In addition, an outer diameter R 1  of the first layer  510  and an outer diameter R 2  of the second layer  520  may be about 3 mm to 8 mm. In addition, the outer diameter R 1  of the first layer may have a size of 92% to 108% of the outer diameter R 2  of the second layer. That is, the outer diameter R 1  of the first layer  510  and the outer diameter R 2  of the second layer  520  are the same as each other, or an outer diameter of one of the first layer  510  and the second layer  520  may be greater. 
     When the outer diameter R 1  of the first layer is less than 92% of the outer diameter R 2  of the second layer, or the outer diameter R 1  of the first layer exceeds 108% of the outer diameter R 2  of the second layer, the frequency of the ultrasonic waves generated from the piezoelectric member  500  is increased. That is, ultrasonic waves having frequencies that are not suitable for cosmetic purposes may be generated from the ultrasound mask, and the number of frequencies oscillating in the flexion mode may be less than three. 
     In addition, an inner diameter r 1  of the first layer  510  may be 0 mm to 1.5 mm (when an inner diameter is 0 mm, the first layer is not formed with a through-hole), and an inner diameter r 2  of the second layer  520  may be about 1.5 mm to 5.6 mm. In addition, the inner diameter r 1  of the first layer  510  may be about 20% or less of the inner diameter r 2  of the second layer  520 . That is, the inner diameter r 1  of the first layer  510  may be smaller than the inner diameter r 2  of the second layer  520 . 
     When the inner diameter r 1  of the first layer  510  exceeds about 20% of the inner diameter r 2  of the second layer  520 , the frequency of the ultrasonic waves generated from the piezoelectric member  500  is increased. That is, ultrasonic waves having frequencies that are not suitable for cosmetic purposes may be generated from the ultrasound mask. 
     In addition, the inner diameter r 2  of the second layer  520  may have a size of about 50% to about 70% of the outer diameter R 2  of the second layer  520 . 
     That is, the inner diameter r 2  of the second layer  520  may be smaller than the outer diameter R 2  of the second layer  520 . 
     When the inner diameter r 2  of the second layer  520  is less than 50% of the outer diameter R 2  of the second layer  520 , or the inner diameter r 2  of the second layer  520  exceeds 70% of the outer diameter R 2  of the second layer  520 , the frequency of the ultrasonic waves generated from the piezoelectric member  500  is increased. That is, ultrasonic waves having frequencies that are not suitable for cosmetic purposes may be generated from the ultrasound mask, and the number of frequencies oscillating in the flexion mode may be less than three. 
     Table 1 below is for describing a frequency band generated when the outer and inner diameters of the first layer  510  and the outer and inner diameters of the second layer  520  are controlled within the above ranges. 
     
       
         
           
               
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 First layer thickness: 300 μm 
                 Resonant frequency (khz) 
               
            
           
           
               
               
               
               
            
               
                 Second layer thickness: 700 μm 
                   
                 Flexion 
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 First layer 
                 First layer 
                 Second 
                 Second 
                   
                 mode 
                   
               
               
                 outer 
                 inner 
                 layer outer 
                 layer inner 
                 Flexion 
                 resonance 2 
                 Flexion 
               
               
                 diameter 
                 diameter 
                 diameter 
                 diameter 
                 mode 
                 (Center 
                 mode 
               
               
                 (mm) 
                 (mm) 
                 (mm) 
                 (mm) 
                 resonance 1 
                 frequency) 
                 resonance 3 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 6 
                 0 
                 6 
                 4 
                 115 
                 232 
                 357 
               
               
                 6 
                 0 
                 5.7 
                 2.5 
                 264 
                 380 
                 501 
               
               
                 5 
                 0 
                 4.8 
                 3 
                 210 
                 338 
                 446 
               
               
                 5 
                 0.4 
                 4.8 
                 2.4 
                 189 
                 335 
                 437 
               
               
                 5 
                 0.1 
                 4.8 
                 3 
                 215 
                 337 
                 445 
               
               
                 5 
                 0 
                 5 
                 2.5 
                 263 
                 392 
                 535 
               
               
                 5 
                 0 
                 4.8 
                 2.3 
                 317 
                 458 
                 535 
               
               
                   
               
            
           
         
       
     
     Referring to Table 1, it can be seen that the ultrasound mask according to the embodiment may implement multiple resonance of the flexion mode by controlling a thickness, an outer diameter, and an inner diameter of the first layer and a thickness, an outer diameter, and an inner diameter of the second layer to a specific numerical range. 
     That is, the ultrasound mask according to the embodiment may have at least two frequencies having a frequency within 150 before and after the center frequency while having the flexion mode. 
     Hereinafter, a manufacturing process of the ultrasound mask according to the first to third embodiments will be described with reference to  FIGS. 27 to 30 . 
     First, the first substrate  110  and the second substrate  120  are prepared, and the first wiring  210  and the second wiring  220  are formed on the first substrate  110  and the second substrate  120 , respectively. 
     Referring to  FIG. 27A , a copper pattern layer serving as a material of a wiring  200  may be formed on a substrate  100 . As described above, the copper pattern layer may extend in the first direction, extend in the second direction, or extend in the first direction and the second direction. 
     Subsequently, referring to  FIG. 27B , the same material as a material of the substrate may be applied on the substrate  100 . In detail, the material of the substrate may be applied as much as a thickness of the wiring  200  disposed on the substrate  100 . 
     Accordingly, the wiring  200  may be disposed on an engraved portion of the substrate  100 , and the embossed portion E may be formed between the engraved portions on which the wiring  200  is disposed. 
     Finally, the first wiring  210  may be formed in a shape impregnated inside the first substrate  100 , and the second wiring  220  may be formed in a shape impregnated inside the second substrate  120 . 
     Subsequently, referring to  FIG. 28 , the piezoelectric member  500  may be disposed above the first substrate  110 . The first electrode  410  and the second electrode  420  may be disposed on the lower surface and the upper surface of the piezoelectric member  500 , respectively. 
     Then, the first adhesive layer  310  including a conductive material is disposed between the first electrode  410  and the first wiring  210 , and the first electrode  410  and the first wiring  210  may be adhered to each other through the first adhesive layer  310  to dispose the piezoelectric member  500  on the first substrate  110 . 
     Subsequently, referring to  FIG. 29 , the second substrate  120  on which the second wiring manufactured previously is formed may be disposed on the first substrate  110 . 
     Then, the second adhesive layer  320  including a conductive material is disposed between the second electrode  420  and the second wiring  220 , and the second electrode  420  and the second wiring  220  may be adhered to each other through the second adhesive layer  320  to dispose the piezoelectric member  500  on the lower surface of the second substrate  120 . 
     That is, the first substrate  110 , the second substrate  120 , and the piezoelectric member  500  may be adhered and electrically connected through the first adhesive layer  310  and the second adhesive layer  320 . 
     Subsequently, referring to  FIG. 30 , the protective layer  150  may be formed in a space between the piezoelectric members  500 , that is, in a space between the piezoelectric members  500  between the first substrate  110  and the second substrate  120 . 
     The protective layer  150  may include the same material as the first substrate  110  and the second substrate  120 , and the first substrate  110 , the second substrate  120 , and the protective layer  150  may be integrated. 
     Alternatively, the protective layer  150  may include a material different from those of the first substrate  110  and the second substrate  120 . For example, the first substrate  110  and the second substrate  120  may include a material that is relatively resistant to stress compared to the protective layer  150 . 
     Subsequently, the first base layer  610 , that is, a backing layer, may be disposed on the lower surface of the first substrate  110 , and the second base layer  620 , that is, a matching layer, may be disposed on the upper surface of the second substrate  120 . 
     The first base layer  610  and the second base layer  620  may include the same material as the first substrate  110  and the second substrate  120 , and the first substrate  110 , the second substrate  120 , and the protective layer  150  may be integrated. 
     Alternatively, the first base layer  610  and the second base layer  620  may include a material different from those of the first substrate  110  and the second substrate  120 . For example, the first base layer  610  and the second base layer  620  may include a material that is relatively resistant to stress compared to the first substrate  110  and the second substrate  120 . 
     The ultrasound mask according to the first to third embodiments may be manufactured by the same process as described above. 
     Hereinafter, a manufacturing process of the ultrasound mask according to the fourth to sixth embodiments will be described with reference to  FIGS. 31 to 35 . 
     Since a process according to  FIGS. 31 to 34  is the same as the process according to  FIGS. 27 to 30  described above, the following description will be omitted. 
     Referring to  FIG. 35 , the first metal layer  711  and the first cover layer  721  may be sequentially formed on the lower surface of the first base layer  610 . 
     In addition, the second metal layer  712  and the second cover layer  722  may be sequentially formed on the upper surface of the second base layer  620 . 
     The metal layers may include copper or the like, and the type of metal is not limited. 
     In addition, the cover layers may include a material the same as or similar to that of at least one of the substrate, the protective layer, and the base layers. 
     The ultrasound mask according to the fourth to sixth embodiments may be manufactured by the same process as described above. 
     Hereinafter, an overlapping relationship between the adhesive layer and the electrode of the ultrasound mask according to the embodiment will be described with reference to  FIGS. 36 and 37 . 
     Referring to  FIGS. 36 and 37 , the first adhesive layer  310  and the second adhesive layer  320  are disposed in a region overlapping one surface of the first electrode  410  and the second electrode  420 . 
     The one surface of the first electrode  410  and the second electrode  420  may be greater than or equal to one surface of the first adhesive layer  310  and the second adhesive layer  320 . That is, a contact area between the electrode and the adhesive layer may be smaller than that of one surface of the electrode. 
     When a region where one surface of the first adhesive layer  310  and the first electrode  410  overlap is defined as a first overlapping region, and a region where the second adhesive layer  320  and the other surface of the second electrode  420  overlap is defined as a second overlapping region, an overlapping area of the first overlapping region and the second overlapping region may be about 20% or more of the entire area of the first electrode  410  or the second electrode  420 . 
     In detail, the overlapping area of the first overlapping region and the second overlapping region may be about 20% to about 100% of the entire area of the first electrode  410  or the second electrode  420 . 
     When the overlapping area of the first overlapping region and the second overlapping region is less than about 20% of the entire area of the first electrode  410  or the second electrode  420 , electrical characteristics of the wiring connected to the first electrode  410  or the second electrode  420  may be deteriorated, and thus reliability of the ultrasound mask may be deteriorated. 
     That is, the first adhesive layer  310  and the first electrode  410  and the second adhesive layer  320  and the second electrode  420  may completely overlap and be adhered to each other, or the first adhesive layer  310  and the second adhesive layer  320  may be in contact with each other while exposing one surface of the first electrode  410  or the second electrode  420 . 
     In addition, overlapping areas of the first overlapping region and the second overlapping region of the adhesive layer disposed on a plurality of electrodes may have a uniform size. 
     For example, a difference between the overlapping areas of the first overlapping region and the second overlapping region of the adhesive layer disposed on the plurality of electrodes may be about 10% or less. In detail, the difference between the overlapping areas of the first overlapping region and the second overlapping region of the adhesive layer disposed on the plurality of electrodes may be 5% to 10%. 
     Accordingly, the ultrasonic waves generated from the plurality of piezoelectric members  500  may be transmitted in a uniform size to each area of the ultrasound mask by minimizing the difference between the overlapping areas of the first overlapping region and the second overlapping region. 
     Hereinafter, an ultrasound mask according to another embodiment will be described with reference to  FIG. 38 . 
     Referring to  FIG. 38 , the ultrasound mask according to another embodiment may include an indicator. In detail, an indicator  800  capable of identifying an operating state of the ultrasound mask may be disposed in one region of the ultrasound mask. 
     The indicator  800  may be disposed on an outer surface of the ultrasound mask so that the user may identify the indicator from the outside. That is, the ultrasound mask may be formed on a surface opposite to a surface on which substances such as cosmetics, and the like are disposed. 
     The indicator  800  may display various operating states of the ultrasound mask. For example, the indicator  800  may display the start/end of the ultrasound mask. Further, the indicator  800  may display a frequency band generated by the ultrasound mask. 
     The indicator  800  may include at least one of members capable of transmitting information to a user visually or aurally such as an LED, a display, and a buzzer. 
     The indicator  800  may be disposed outside the ultrasound mask  1000  to display an operation state of the ultrasound mask  1000 . As an example, the indicator  800  may provide information on the start of the operation of the ultrasound mask  1000 , information indicating that the operation is in progress, and information on the completion of the operation through auditory information generated from a buzzer. In addition, the indicator  800  may display the operation state according to the emission color of the LED. In addition, the indicator may display information on an operating frequency region through the display. 
     In addition, the indicator  800  may provide information on whether the ultrasound mask  1000  is closely adhered to the skin. 
     Hereinafter, an ultrasound mask according to still another embodiment will be described with reference to  FIGS. 39 to 43 . 
     Referring to  FIGS. 39 to 43 , the ultrasound mask according to still another embodiment may include a plurality of spacers  900  disposed on the base layer. 
     In detail, the ultrasound mask according to the embodiment may include the plurality of spacers  900  disposed on the second base layer  620  close to the skin, that is, the matching layer. 
     The plurality of spacers  900  may be disposed to be spaced apart from each other. For example, each of the spacers  900  may be disposed so as not to overlap a region where the piezoelectric member  500  is disposed. In detail, each of the spacers  900  may be disposed so as not to overlap the region where the piezoelectric member  500  is disposed so as not to affect the movement of the piezoelectric member to which the ultrasonic waves generated from the piezoelectric member  500  are transmitted. That is, the spacers  900  may be respectively disposed between the piezoelectric members  500 . 
     The spacer  900  may be disposed on the matching layer to which a cosmetic ingredient  950  including cosmetics or drug substances applied to the skin of the human body is applied to prevent the cosmetic substances or drug substances from being aggregated in one region. 
     In detail, referring to  FIG. 40 , when the ultrasound mask is in contact with a material such as cosmetics applied to the skin, the material such as cosmetics moves outward form the region where the piezoelectric member is disposed by vibration and pressure generated from the piezoelectric member, so that a step may be formed. 
     Accordingly, an amount of the cosmetic substance is reduced in the region where the piezoelectric member is disposed, and thus the efficiency of movement of the cosmetic substance through ultrasonic waves may be deteriorated. 
     Accordingly, as shown in  FIG. 41 , by disposing the plurality of spacers  900  between regions in which the piezoelectric member is disposed, the cosmetic substances, and the like are moved to the outside when the ultrasound mask is in contact with the skin, and thus it is possible to prevent the amount of the cosmetic substances, and the like from being reduced in a region overlapping the piezoelectric member. 
     Referring to  FIGS. 42 and 43 , the spacers  900  may be disposed to be spaced apart in a dot shape between the piezoelectric members  500  as shown in  FIG. 38  or may be formed in a linear shape connected to each other between the piezoelectric members  500  as shown in  FIG. 39 . 
     In the ultrasound mask according to still another embodiment, a plurality of spacers spaced apart from each other are disposed in a region not overlapping the piezoelectric member, and the ultrasound mask is in contact with the skin, and then it is possible to prevent the cosmetic material from being aggregated into one region by vibration and pressure generated from the piezoelectric member. 
     Therefore, it is possible to improve the efficiency of transmitting cosmetic substances of the ultrasound mask according to still another embodiment. 
     Hereinafter, an example of using the ultrasound mask according to the embodiment will be described with reference to  FIGS. 44 and 45 . 
       FIG. 44  is a view illustrating a user wearing a mask according to an embodiment, and  FIG. 45  is a view illustrating a skin care device to which the mask according to the embodiment is applied. 
     Referring to  FIG. 44 , the user may wear the ultrasound mask  1000 . The ultrasound mask  1000  may include the above-described opening  1010 , and the user may secure a view through the opening  1010 . In addition, the mask  1000  may include the above-described cutout portion  1020 , and the ultrasound mask  1000  may be effectively close-adhered to the curved skin by the cutout portion  1020 . In this case, one surface of the second base layer  620  may be in direct contact with the user&#39;s skin. 
     The ultrasound mask  1000  may be operated by receiving power through an external power connected to the ultrasound mask  1000 . In addition, the ultrasound mask  1000  may be operated by receiving power through a power supply unit (not shown) disposed outside the ultrasound mask  1000 , for example, on a lower surface of the second base layer  620 . 
     In addition, referring to  FIG. 45 , the mask  1000  may be applied to a skin care device  1  to operate. In detail, referring to  FIG. 41 , the skin care device  1  may include a main body  10  in which one side thereof is open and including an accommodation space  11  therein. 
     The main body  10  may include a material that may be light and prevent damage from external impact or contact. As an example, the main body  10  may include a plastic or ceramic material, may have improved reliability from an external environment, and may protect the mask  1000  disposed inside the accommodation space  11 . In addition, the main body  10  may include a viewing part  13  formed at a position corresponding to the user&#39;s eyes. The viewing part  13  may be formed in a region corresponding to the opening  1010  of the mask  1000 , and the user may secure an external view through the viewing part  13 . 
     The ultrasound mask  1000  may be disposed in the accommodation space  11  of the main body  10 . The ultrasound mask  1000  may be disposed between the main body  10  and the user&#39;s skin. In detail, the first base layer  610  of the ultrasound mask  1000  may be disposed to face the accommodation space  11  of the main body  10 , and the second base layer  620  of the ultrasound mask  1000  may be disposed to face the user&#39;s skin. 
     The ultrasound mask  1000  may be coupled to the main body  10 . For example, the ultrasound mask  1000  may be fixed to a set position in the accommodation space  11  by a fastening member (not shown) and may have a structure that is detachable from the main body  10 . 
     The ultrasound mask  1000  may receive power through the power supply unit (not shown) disposed outside the mask  1000 . Alternatively, the ultrasound mask  1000  may be connected to the main body  10  to receive power through the power supply unit (not shown) disposed on the main body  10 . 
     The ultrasound mask  1000  may further include a buffer member (not shown) disposed on the lower surface of the first base layer  610 . The buffer member may be in direct contact with the first base layer  610  and may be disposed facing the accommodation space  11  of the main body  10 . That is, a deformable member may be disposed between the main body  10  and the first base layer  610  of the mask  1000 . 
     The deformable member may include a material of which shape is changed by external pressure. For example, the deformable member may include a material such as an air gap or a sponge, but the embodiment is not limited thereto, and may include various materials of which shape is changed by external pressure. Accordingly, when the user puts on the skin care device  1 , the deformable member may be deformed into a shape corresponding to the shape of the user&#39;s face. Therefore, the ultrasound mask  1000  and the user&#39;s skin may be effectively close-adhered to each other. 
     In addition, when a plurality of users put on the skin care device  1 , the deformable member is deformed to correspond to each face shape, so that the user&#39;s skin and the mask  1000  may be effectively close-adhered to each other. 
     The characteristics, structures, effects, and the like described in the above-described embodiments are included in at least one embodiment of the present invention, but are not limited to only one embodiment. Furthermore, the characteristic, structure, and effect illustrated in each embodiment may be combined or modified for other embodiments by a person skilled in the art. Thus, it should be construed that the contents related to such combination and modification are included in the scope of the present invention. 
     In addition, the above description has been focused on the embodiments, but it is merely illustrative and does not limit the present invention. Those skilled in the art to which the embodiments pertain may appreciate that various modifications and applications not illustrated above are possible without departing from the essential features of the embodiment. For example, each component particularly represented in the embodiments may be modified and realized. In addition, it should be construed that differences related to such a modification and an application are included in the scope of the present invention defined in the appended claims.