Abstract:
A device for skin treatment, which precisely transmits high-frequency energy to a target portion of skin tissue without causing a burn on the outer layer of the skin, thus artificially damaging the portion and inducing a wound curing reaction, therefore leading to the regeneration of skin and the propagation of collagen. The device prevents the surface of skin from suffering an injury during insertion, alleviates pain, and keeps the depth to which the needle is inserted into the skin uniform. The device includes a plurality of needles coated with an insulator except for sharp ends. A needle holding unit holds the needles. A drive unit directly or indirectly transmits a force to the needle holding unit, thus allowing the needles to be inserted into the skin. An electromagnetic wave transmitting unit is electrically connected to the needles and transmits electromagnetic waves to the needles.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. national phase of International Patent Application No. PCT/KR2010/00200 filed Jan. 13, 2010, which claims the benefit of Korean Application No. 10-2009-0006081 filed Jan. 23, 2009, both of which are incorporated herein by reference. This application also claims the priority of Korean Patent Application No. 10-2009-0060237, filed Jul. 2, 2009 in the Korean Patent Office, which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field of the Invention 
     The invention relates generally to a device for skin treatment and, more particularly, to a device for skin treatment, which is constructed such that a plurality of needles coated with an insulator is inserted into the skin and an electromagnetic wave is transmitted through the needles inserted into the skin. 
     2. Description of the Related Art 
     As seen in paper 1 (Hyun-Ju Jeong, The measurement of the thickness of the Korean&#39;s skin by ultrasound, KyungBuk Univ., 1990. Vol. 28(2), 121-129) and paper 2 (Jin-Sung Park, The measurement of the thickness of the Koreans&#39; skin by a CT scan, Catholic Univ., 1995. Vol. 33, 303-311), the thickness of an Oriental&#39;s skin is generally about 1.5 mm to 4.0 mm, and the thickness of the outer layer of the skin is about 0.06 mm to 0.2 mm. 
     For example, in terms of the thickness of the skin, the cheek which has the thickest skin is about 2.7 mm (±0.40 mm), and the forehead and the eyelid which have the thinnest skin are about 0.84 mm. 
     A person&#39;s skin consists of an outer layer and an inner layer. The inner layer serves as the main support of the skin and is made up of a protein which is called collagen. The collagen has a triple helical structure including a fibroblst and a polypeptide. If the collagen tissue is heated, the protein matrix is physically changed at the shrinkage temperature. The remodeling of soft tissue is a physical change that occurs at the cellular or molecular level. The shrinkage or the partial denaturization of collagen generated by artificial heat decomposes the bonding of a triple helix, thus destroying the intermolecular bonding of the matrix. When it is compared with the shrinkage resulting from the movement of fibroblasts into a wound and natural healing power, the remodeling of soft tissue is an immediate process. When cells shrink, the collagen is situated at a lower position and acts as a static support matrix for the taut soft tissue. The initial deposition of a scar matrix and the subsequent remodeling provide means for changing the shape and consistency of soft tissue for beauty purposes. 
     Generally, in order to treat various scars or skin lesions or to improve the skin or wrinkles for the sake of beauty, a method of applying various energy sources to an associated portion and solidifying the tissue has been used. For example, methods of transferring thermal energy have been proposed. 
     According to the methods, various kinds of energy are applied to the target portions of the skin tissue to intentionally cause wounds, thus stimulating the collagen of the inner layer and inducing the regenerating action of the collagen, therefore regenerating skin tissue. 
     Referring to papers, it is reported that the denaturization of collagen occurs most reliably at a temperature from 65° C. to 75° C. However, the effects of treatment may vary according to how the patient endures the pain at this temperature. 
     Conventionally, a target portion of the skin is heated by radiating light, near infrared rays, and microwaves. According to the conventional methods, heat is applied to the outer layer of the skin to reach the target portion of the skin. 
     However, when thermal energy is transmitted from the outer portion of the skin to the target portion (the outer layer, inner layer, or subcutaneous fat) of skin tissue, the thermal energy is greatly scattered or absorbed. Thus, there is less energy to be substantially transmitted to the inner layer. If the thermal energy which is applied to the skin is increased to solve the problem, the outer layer is burned. 
     Further, a method of using physical energy has been proposed. According to the method, a superfine needle is inserted into a target portion of the skin tissue to physically stimulate it. However, the method is problematic in that a user personally inserts the needle into the skin, so that it is difficult to precisely control the depth to which the needle is inserted into the target portion of skin tissue. When this method is used, the skin is damaged only physically and not damaged thermally, so that the effect of regenerating collagen or damaged skin is restricted. Further, if the needle is inserted at an angle to the outer layer of the skin, an incident angle differs from an emergent angle, so that a wound may undesirably result and the inner layer of the skin may be stimulated. 
     Further, when a roller equipped with a plurality of needles is rubbed against the skin, an incident angle differs from an emergent angle, thus causing an undesirable wound and pain. 
     Further, the important parameters of a conductive needle which transmits electromagnetic waves to the skin include the angle of the conductive needle when it is inserted into the skin and the diameter of the conductive needle. Since pain and a burn are caused when the conductive needle is inserted into the skin, there is a need for the development of a conductive needle which is optimized to eliminate the pain and burning. However, the conventional conductive needle is manufactured indiscriminately without taking into consideration the angle and diameter of the conductive needle. Therefore, it is difficult to eliminate the pain and burning. 
     A conventional device having a needle unit is problematic in that needles to which high-frequency waves are applied are inserted directly by a user using his or her hand, so that the depth of insertion, the strength, a balanced state during insertion, and the time it takes to perform the insertion are not constant. Consequently, the conventional device varies in treatment effect, pain, and operation time, so that it is difficult to standardize the treatment effect, pain, and operation time. 
     In order to accomplish the purpose of a desired treatment, a plurality of needles must be almost simultaneously inserted into the body, and electric energy must be applied to ends of the needles. When the plurality of needles is inserted into a very shallow layer of the skin, the depth of the end of each needle must be precisely controlled according to a predetermined value. 
     When the plurality of needles is not controlled horizontally as shown in  FIG. 1 , the surface of the skin may be undesirably damaged. Therefore, a method of controlling the plurality of needles horizontally is required. 
     Further, in the case of inserting the device into the human body, it must always be inserted into the skin using regular pressure so as to lessen the sensation of fear and pain of a patient. 
       FIG. 2  is a graph illustrating survey results regarding the fear and pain felt when medical treatment is performed on people receiving clinical treatment using irregular pressure. The graph shows that people receiving clinical treatment suffer more fear and pain under irregular pressure in comparison with regular pressure. 
     The needles inserted into the skin must always be dislodged from the skin within a predetermined period of time so as to remove the danger of an accident and lessen the pain. 
     If the needles are dislodged from the skin at a different time for each shot during the medical treatment, the skin may be scratched by the needles or high-frequency waves may be directly applied to the outer layer of the skin while one portion of the skin has been treated and then the needles are moved, so that the skin may be undesirably damaged as shown in  FIG. 3 . Further, if the needles stay in the skin for a lengthy period of time, a patient&#39;s pain increases. 
       FIG. 4  is a graph showing survey results for people receiving clinical treatment. As shown in the drawing, as time for inserting the needles into the skin increases, the number of people receiving clinical treatment who feel pain increases. 
     The conventional device is problematic in that it is impossible to know the replacement time even if the needles are no longer being used. 
     As shown in  FIGS. 5 to 7 , when a predetermined period of time has passed or the needles have been used for a predetermined number times, the ends of the needles are undesirably burnt or bent. Thus, when a predetermined period of time has passed or the needles have been used for a predetermined number times, it is necessary to prevent the use of the needles for safety&#39;s sake. Further, in the case of simultaneously using a bipolar type needle and a monopolar type needle, a user must control the amount of energy or know whether opposite pole plates are installed or not. Thus, means for storing and displaying these pieces of information is required. 
     The method and object of treatment depend on the using amount or characteristics of the needles. Thus, a sensing device is required to read pieces of information of the needles and control the parameters of the equipment. 
     If the needles are inserted into the skin to a depth of 0.2 mm or more and high-frequency energy is applied, a very small amount of protein denaturation occurs. The denatured protein sticks to the needles, so that the needles are not easily removed from the skin. 
     If the needles slide horizontally with not being removed from the skin, the skin is damaged by the needles as shown in  FIG. 3 . 
     Further, when the plurality of needles is inserted into the skin, the longer the time taken to insert the needles into the skin is, the greater a patient&#39;s fear and pain are. Thus, it is required to reduce the time taken to insert as much as possible. Further, when the needles are inserted using the hand, fine vibrations are generated rightward and leftward. A treatment which is not standardized increases the patient&#39;s fear and pain.  FIG. 8  is a diagram showing patients&#39; pain as a function of the speed and method used to insert the needles. 
     A pushing force of an electric-powered device such as a solenoid valve is weaker than a recovery force, so that a means for supplementing the recovery force and aiding in removing the needles from the skin is required. Therefore, it is required to reduce the time it takes to separate the needles from the skin for safety&#39;s sake, thus reducing the stress of an operator and a patient. 
     SUMMARY 
     Accordingly, the invention has been made keeping in mind the above problems occurring in the prior art, and an embodiment of the invention provides a device for skin treatment, in which a needle passes through an outer skin layer to be inserted into an inner skin layer or the desired skin tissue and applies high-frequency energy thereto, thus allowing the skin to be treated without causing a burn. 
     An embodiment of the invention provides a device for skin treatment, which is capable of precisely transmitting energy to a desired portion of skin tissue. 
     An embodiment of the invention provides a device for skin treatment, which optimizes the shape of a needle so that incident and emergent angles of the needle relative to the skin are equal to each other, and the insertion speed and the recovery speed are standardized and increased, thus lessening an operator&#39;s stress and alleviating a patient&#39;s pain. 
     An embodiment of the invention provides a device for skin treatment, which automatically controls the kind, life span, and other pieces of information about a needle that is an article of consumption, thus enhancing reliability. 
     In order to accomplish the above objects, an embodiment of the invention provides a device for skin treatment including a plurality of needles, portion of each of the needles except for a sharp end being coated with an insulator, a needle holding unit for holding the needles, a drive unit for directly or indirectly transmitting a force to the needle holding unit, thus allowing the needles held by the needle holding unit to be inserted into the skin, and an electromagnetic wave transmitting unit electrically connected to the needles and transmitting electromagnetic waves to the needles. 
     As is apparent from the above description, such a device for skin treatment is advantageous in that a burn produced on the surface of the skin during the insertion of a conductive needle is eliminated and the pain is alleviated, and the insertion of the conductive needle into the skin is uniformly carried out, thus allowing the skin to be more efficiently treated as electromagnetic waves are applied. Further, safer treatments are possible because information about a needle is controlled using memory. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages will be more clearly understood from the following detailed description of various embodiments taken in conjunction with the accompanying drawings, in which: 
         FIGS. 1 to 8  are views illustrating the problems of a conventional device for skin treatment; 
         FIG. 9  is a view illustrating the construction of a device for skin treatment according to an embodiment of the invention; 
         FIG. 10  is a view illustrating a needle inserted into the skin, according to an embodiment of the invention; 
         FIGS. 11A to 11D  are views respectively illustrating a plurality of needles according to an embodiment of the invention; 
         FIG. 12  is a view illustrating the arrangement of a plurality of needles according to an embodiment of the invention; 
         FIGS. 13 to 15  are views illustrating the arrangement of needles according to an embodiment of the invention; 
         FIG. 16  is a view illustrating the assembly of a plurality of needles according to an embodiment of the invention; 
         FIG. 17  is a view illustrating the function of a skin support member according to an embodiment of the invention; 
         FIG. 18  is a view illustrating a drive unit according to an embodiment of the invention; 
         FIG. 19  is a view illustrating the operation of an adjusting member according to an embodiment of the invention; 
         FIG. 20  is a view illustrating the use of another adjusting member according to an embodiment of the invention; 
         FIG. 21  is a view illustrating the use of a further adjusting member according to an embodiment of the invention; 
         FIGS. 22 to 24  are views illustrating the shape of insertion limiting members according to an embodiment of the invention; 
         FIGS. 25A and 25B  are views illustrating the construction of a cavity body according to an embodiment of the invention; 
         FIGS. 26A and 26B  are views illustrating a cooling structure for a cavity body according to an embodiment of the invention; 
         FIG. 27  is a view illustrating the construction of a thermoelement provided in the cavity body according to an embodiment of the invention; 
         FIG. 28  is a view illustrating the assembly of the drive unit according to an embodiment of the invention; 
         FIG. 29  is a view illustrating a cold air injection nozzle according to an embodiment of the invention; 
         FIGS. 30 to 32  are views illustrating embodiments of the drive unit according to an embodiment of the invention; 
         FIGS. 33 and 34  are views illustrating cooling structures for the insertion limiting member according to an embodiment of the invention; and 
         FIG. 35  is a view illustrating a drug feeding structure according to an embodiment of the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, the construction and operation of embodiments of the invention will be described with reference to the accompanying drawings. 
       FIG. 9  is a view illustrating the construction of a device for skin treatment according to an embodiment of the invention. The skin treating device  10  includes a plurality of needles  100 , a needle holding unit  200 , a drive unit  300 , and an electromagnetic wave transmitting unit  400 . The needle holding unit  200  functions to hold the needles  100 . The drive unit  300  directly or indirectly transmits a force to the needle holding unit  200  so that the needles  100  held by the needle holding unit  200  are inserted into the skin. The electromagnetic wave transmitting unit  400  is electrically connected to the needles  200  to transmit electromagnetic waves to the needles  100 . 
     As soon as the needles  100  are inserted into the skin, they are held by the needle holding unit  200 . One end of each needle  100  has a diameter of from 0.1 mm to 0.4 mm, while the other end is sharp. If one end of the needle  100  has a diameter less than 0.1 mm, the needle  100  may be easily bent and thus tear the skin when inserted into the skin. Meanwhile, if one end of the needle  100  has a diameter greater than 0.4 mm, pain and a burn may result when the needle  100  is inserted into the skin. 
     Preferably, the needle  100  is bent in one or more stages such that its angle changes between one end and the other end of the needle  100 . Meanwhile, the needle  100  may be rounded without being bent between one end and the other sharp end. Such a shape serves to alleviate the pain caused when the needle  100  is inserted into the skin. 
     Further, portion of each needle  100  except for the sharp end is preferably coated with any one of Parylene, Teflon, and ceramic to a thickness of from 5 μm to 25 μm. Such a coating enables electromagnetic waves transmitted through the needles  100  to the skin to be emitted to a desired depth in the skin. The coating layer preferably has a thickness of from 5 μm to 25 μm so as to maintain the advantages of the Parylene coating and to prevent impurities from remaining after the coating operation. Parylene coating is thermally excellent because its properties, such as thermal or mechanical deformation, do not change within a range from −200° C. to 150° C. Parylene coating enables a coating layer to be uniformly formed on the surface of the needle  100 , in addition to permitting the adjustment of the thickness of the coating layer. Parylene coating is harmless to humans. The ceramic coating may use Al 2 O 3 , ZrO 2 , glass ceramics, carbon, etc. The needle  100  may be made of stainless steel, for example, SUS303. 
     In order to emit electromagnetic waves to a desired depth of skin, each needle  100  is preferably shaped such that a first straight line connecting a first point which is in contact with the skin when the needle  100  is inserted into the skin with a sharp point of the needle end forms an angle of from 14° to 30° with a second straight line connecting a second point which faces the first point with the sharp point of the needle end. 
     That is, assuming that the sharp point of the needle  100  is denoted by C, the first point is denoted by A, and the second point is denoted by B, and the first straight line connecting C with A forms an angle of from 14° to 30° with the second straight line connecting C with B, as shown in  FIG. 10 , electromagnetic waves are transmitted to the skin without inducing pain. When the angle between the first straight line and the second straight line is less than 14°, the end of the needle  100  becomes excessively thin, so that the needle  100  may be easily bent. Meanwhile, when the angle between the first and second straight lines is greater than 30°, the end of the needle  100  becomes dull, so that the needle  100  is not smoothly inserted into the skin and pain increases. 
     The needles  100  will be described in more detail with reference to the embodiments of  FIGS. 11A to 11D . 
     A portion of each needle  100  from its sharp end to a first point, bent to be inclined relative to the sharp end at the angle of from 14° to 30°, is non-insulated. A portion of the needle  100  from the first point to a second point, bent to be inclined relative to the first point at the angle of from 2.5° to 12.5°, is coated with an insulator. A portion of the needle  100  from the second point to an end facing the sharp end is coated with an insulator while maintaining the diameter of 0.25 mm without being bent, so that electromagnetic waves are transmitted to the skin at the non-insulated portion. 
     To describe in detail, the needle  100  has a circular cross-section and is shaped such that its diameter is reduced from one end to the other end. Further, the needle  100  is bent in two stages and is sharp at the other end. The entire length of the needle  100  is preferably about 1.5 cm. 
     The needle  100  includes a first insulating portion  110 , a second insulating portion  120 , and a non-insulating portion  130 , which are integrated with each other. The first insulating portion  110  has a diameter of 0.25 mm±0.05 mm, and is secured to the needle holding unit  200  which holds the needle  100  to allow it to be easily inserted into the skin. 
     The needles  100  may be formed as shown in the embodiments of  FIGS. 11A to 11D . 
     That is, as shown in  FIG. 11A , a needle is formed such that a portion extending from a sharp end to a first point, bent to be inclined relative to the sharp end at an angle of 22°, and having the length of about 0.26 mm±0.02 mm is non-insulated. Further, a portion of the needle extending from the first point to a second point, bent to be inclined relative to the first point at an angle of 7.5°, and having the length of about 1.13 mm±0.02 mm is coated with an insulator to a thickness of 10 μm±2 μm. A portion of the needle extending from the second point to an end facing the sharp end is coated with an insulator to a thickness of 10 μm±2 μm while maintaining the diameter of 0.25 mm without being bent. Electromagnetic waves are transmitted to the skin through the needle. 
     Next, as shown in  FIG. 11B , a needle is formed such that a portion extending from a sharp end to a third point, bent to be inclined relative to the sharp end at an angle of 30°, and having the length of about 0.17 mm±0.02 mm is non-insulated. Further, a portion of the needle extending from the third point to a fourth point, bent to be inclined relative to the first point at an angle of 7.5°, and having the length of about 1.13 mm±0.02 mm is coated with an insulator to a thickness of 10 μm±2 μm. A portion of the needle extending from the fourth point to an end facing the sharp end is coated with an insulator to a thickness of 10 μm±2 μm while maintaining the diameter of 0.25 mm without being bent. Electromagnetic waves are transmitted to the skin through the needle. 
     A needle of  FIG. 11C  has the same structure as that of  FIG. 11B , but is different from that of  FIG. 11B  because the coating thickness of the insulator is 20 μm±2 μm. The coating layer of  FIG. 11C  is thicker than that of  FIG. 11B , thus preventing heat generated from the needle when electromagnetic waves are radiated from being transmitted to outside of the coating layer. 
     Further, as shown in  FIG. 11D , a needle is formed such that a portion extending from a sharp end to a fifth point, bent to be inclined relative to the sharp end at an angle of 15°, and having the length of about 0.26 mm±0.02 mm is non-insulated. Further, a portion of the needle extending from the fifth point to a sixth point, bent to be inclined relative to the fifth point at an angle of 7.5°, and having the length of about 1.13 mm±0.02 mm is coated with an insulator to a thickness of 15 μm±10 μm. A portion of the needle extending from the fifth point to an end facing the sharp end is coated with an insulator to a thickness of 15 μm±10 μm while maintaining the diameter of 0.25 mm without being bent. Electromagnetic waves are transmitted to the skin through the needle. 
     The electromagnetic waves preferably range from 10 KHz to 100 MHz. A material of the needle  100  is stainless steel, and the thermal conductivity of the stainless steel is 14 cal/° C. Further, the needle  100  may be made of a general aluminum material. 
     Preferably, 4 to 81 needles  100  are held by the needle holding unit  200  to form a group, and are inserted into the skin. That is, a proper number of needles  100  is selected according to the area of a portion which is to be treated, thus applying high-frequency waves to only the target portion. Especially, as shown in  FIG. 12 , an interval (D of  FIG. 12 ) between neighboring needles preferably ranges from 0.4 mm to 3.0 mm. When the needles  100  are used to pull skin tissue and thereby reduce the area and volume of the skin tissue, the needles  100  are secured so as to form an interval of from 1.0 mm to 3.0 mm. Meanwhile, when the needles  100  are used to denature an entire portion like a scar, the interval between the needles  100  preferably ranges from 0.4 mm to 1.0 mm. 
     Further, it is preferable that a depth of the needles  100  inserted into the skin range from 0.3 m to 2.5 cm. The thickness of the skin except for a subcutaneous fat layer varies according to the region. The thickest portion of the skin is about 4 mm. In the case of improving the skin or scar, it is preferable that the depth of insertion of the needle range from 0.3 mm to 2 mm. In the case of treating the abdominal fat or the subcutaneous fat of a region of fat, it is preferable that the insertion depth of the needle range from 2 mm to 2.5 cm. 
     Moreover, the plurality of needles  100  is preferably arranged such that a distance (E of  FIG. 12 ) between the first needle to the last needle ranges from 2 mm to 20 mm. If the distance E exceeds 20 mm, it is difficult for the skin to be completely in contact with the needles  100 , and it is difficult to treat the skin under regular pressure, so that the skin may be scratched. If the distance E is less than 2 mm, the area treated is very small, so that the efficiency of treatment is low. 
     As shown in  FIGS. 13 to 15 , the needles  100  held by the needle holding unit  200  may comprise two or more kinds having different lengths. 
     For easy replacement when the needles  100  held by the needle holding unit  200  can no longer be used, the plurality of needles  100 , the needle holding unit  200 , and the electromagnetic wave transmitting unit  400  are preferably formed into one assembly  140 . Referring to  FIG. 16 , an internal casing  600  is further provided, so that the needles  100 , the needle holding unit  200 , and the electromagnetic wave transmitting unit  400  are fitted into the open upper portion of the internal casing  600  to be protected. The internal casing  600  has in its lower portion a plurality of first holes  610  through which the needles  100  pass. 
     The device also includes a skin support member  700 . The skin support member  700  has, on its lower portion which is in contact with the skin, second holes  710  to permit the passage of the needles  100 , and is open at its upper portion. The assembly  140  having the needles  100 , the needle holding unit  200 , the electromagnetic wave transmitting unit  400  and the internal casing  600  is accommodated in the skin support member  700  through its open upper portion in such a way that the needles  100  pass through the second holes  710 . If necessary, the needle holding unit  200  may be combined with the skin support member  700  without the internal casing  600 . 
     The skin support member  700  functions to prevent the needle holding unit  200  holding the needles  100  from directly striking the skin. If the needle holding unit  200  should directly strike the skin, pain is caused when the needle holding unit  200  comes into contact with the skin. Thus, the skin support member  700  is positioned between the needle holding unit  200  and the skin, thus preventing the operating friction of the needle holding unit  200  from being directly transmitted to the skin. The skin support member  700  is preferably made of stainless steel having the thermal conductivity of 14 cal/° C. 
     The skin support member  700  allows the assembly  140  to be smoothly replaced by another one. Further, one or more elastic members  800  are provided on the surface of the skin support member  700  having the second holes  710 , that is, the inner surface of the skin support member  700  which is not in contact with the skin, thus allowing the needles  100  to be immediately removed from the skin by the restoring force of the elastic members  800 . Of course, the elastic members  800  may be provided between the needle holding unit  200  and the first holes  610 . 
     Each elastic member  800  preferably comprises a spring. The elastic member  800  preferably has elastic restoring force such that the needles  100  inserted into the skin by being struck are removed from the skin within 2 seconds using elastic force. If the needles  100  are removed from the skin within 2 seconds, the surface of the skin is not scratched and the operating efficiency is improved. 
     For example, it is most preferable that the elastic members  800  be attached to the corners of the skin support member  700 , respectively. Preferably, the assembly  140  having the conductive needles  100 , the needle holding unit  200 , and the electromagnetic wave transmitting unit  400  is preferably positioned at the height of the elastic members  800  attached to the skin support member  700 . That is, the needle holding unit  200  is located in a region within 3 cm from the bottom of the skin support member  700 . 
     Such a construction allows the conductive needles  100  inserted into the skin to be immediately removed therefrom within 2 seconds by the elasticity of the elastic members  800 , and allows the needles  100  to be again rapidly inserted into the skin by being struck. 
     Meanwhile, an elastic structure may be provided instead of the elastic members  800  on the drive unit  300  so that the assembly  140  is moved up by the elasticity. That is, the elastic members  800 , which differ in construction from the above-mentioned elastic members  800  and have elastic restoring force to move the needle holding unit  200  away from the skin, may accomplish the object of the invention. For example, the elastic members  800  may be placed between the needle holding unit  200  and the internal casing  600 . The elastic members  800  may adopt various shapes, including those of a compression coil spring, a tension coil spring, and elastic rubber. 
     The assembly  140  may further include a memory unit  900  which contains data about the plurality of needles  100 . 
     The memory unit  900  includes counting data about the number of times the needles  100  are inserted into the skin, time data about a time they are used after a mounting operation is first performed, and data about the arrangement and length of the conductive needles. 
     Further, a first connecting signal generated when the memory unit  900  is connected to a central processing unit (CPU)  1100  is transmitted to the CPU  1100  as time data. Thereafter, the CPU  1100  performs a counting operation for a preset time, and stops the operation of the assembly  140  after the preset time has passed. Further, the CPU  1100  counts the number of times the needles  100  are inserted into the skin, thus checking the lifespan of the needles  100 . 
     When the needles  100  have been used for a lengthy period of time, the needles  100  become burnt or bent. Hence, after a predetermined amount of time has passed or they have been used for a preset number times, the CPU  1100  limits the use of the needles  100 . 
     The electromagnetic waves preferably range from 10 KHz to 100 MHz. Since a pulsation period stimulating normal muscle of the body tissue ranges from 0.001 ms to 1 ms, that is, is very short, the application of the electromagnetic waves of high frequency is effective. 
     Preferably, the needle holding unit  200  is located within a distance of from 5 mm to 3 cm from the skin into which the needles  100  are to be inserted. If the needle holding unit  200  holding the plurality of needles  10  directly strikes the skin, pain is caused. When the distance between the needle holding unit  200  and the skin is less than 5 mm, pain which is the same as the pain when the needle holding unit  200  directly strikes the skin is caused. Meanwhile, if the distance between the needle holding unit  200  and the skin is greater than 3 cm, the needles  100  become long and thus may be easily bent. 
     Preferably, a first cover  620  which covers the internal casing  600  and a second cover  720  which covers the skin support member  700  and has a third hole  721  to transmit a force to the assembly  140  are further provided. 
     Hereinbefore, the plurality of needles  100  and peripheral components have been described. Now, the drive unit  300  will be described in detail. 
     The drive unit  300  directly or indirectly transmits a force to the needle holding unit  200  such that the needles  100  held by the needle holding unit  200  are inserted into the skin. 
     For example, in the case of directly transmitting the force, the drive unit  300  is directly secured to the needle holding unit  200  and performs a vertical motion so that the needles  100  are inserted into the skin. In contrast, in the case of indirectly transmitting the force, the drive unit  300  strikes the needle holding unit  200  and applies a force to the needle holding unit  200  to move it downward. 
     Preferably, the drive unit  300  is driven by any one of an electromagnetic valve, a hydraulic valve, a pneumatic valve, and a solenoid valve, which are operated by electric signals.  FIGS. 30 and 31  illustrate the embodiments of the drive unit  300  which is driven by pneumatic force. The drive unit  300  of  FIG. 30  is used in case the number of needles  100  is large. For example, referring to  FIG. 30 , the drive unit  300  driven by pneumatic force includes a pneumatic inlet  302  and a pneumatic outlet  304 . The drive unit  300  is operated such that a rod moves downward when air flows from the pneumatic inlet  302  to the pneumatic outlet  304 . Meanwhile, the drive unit  300  of  FIG. 31  is used in case the number of needles  100  is small. The drive unit  300  of  FIG. 31  uses the same port, as the pneumatic inlet  302  and the pneumatic outlet  304 . That is, if air flows into the pneumatic inlet  302 , the rod moves downward. Meanwhile, the upward movement of the rod is realized by a return spring  306 . When the rod is moved upward by the elastic restoring force of the return spring  306 , air introduced into the pneumatic inlet  302  is discharged from the pneumatic outlet  304 . 
     Meanwhile, the drive unit  300  includes a first coupling part to allow the needle holding unit  200  to be fitted into and assembled with the first coupling part. Preferably, the drive unit  300  also includes a second coupling part  312  to allow an adjusting member  320 , which is for adjusting the depth of the needles  100  inserted into the skin, to be assembled therewith. 
     Further, both the first coupling part for assembling the needle holding unit  200  and the second coupling part  312  for assembling the adjusting member  320  which is for adjusting the depth of the needles  100  inserted into the skin may be integrally formed on the drive unit  300 . 
     For example, as shown in  FIG. 18 , the first coupling part for assembling the needle holding unit  200  comprises first grooves  311 , and the second coupling part for assembling the adjusting member  320  which adjusts the length of the needles inserted into the skin comprises second grooves  312 . 
     In detail, as shown in  FIG. 18 , when the drive unit  300  is a solenoid valve, the first coupling part and the second coupling part may be integrated with the drive unit  300  and apply a force to the needles  100  so that they are inserted into the skin. The first and second coupling parts may be designed to be different from the structure of  FIG. 18 . 
     As shown in  FIG. 18 , the adjusting member  320  has on its opposite sides protrusions  322  which are fitted into the second grooves  312 . The adjusting member  320  includes a body  321  which is integrated with the protrusions  322 . The body  321  is fitted to the drive unit  300 . 
     For example, in the case of the solenoid valve as shown in  FIG. 19 , when the needles  100  are struck by a force of the drive unit  300 , the height from which the striking takes place is determined by the thickness of the body  321 . That is, if the body  321  is thin, the striking operation is performed at a higher position. In contrast, if the body  321  is thick, the striking operation is performed at a lower position. In this way, the depth of the needles  100  inserted into the skin is adjusted. 
     Consequently, the contact of the adjusting member with the drive unit when the body  321  is thick is performed prior to the contact when the body  321  is thin, so that force transmitted to the needles  100  is weak. Thus, the adjusting member  320  can adjust the depth of the needles  100  inserted into the skin. 
     Preferably, the adjusting member  320  may have a plurality of locking steps  330  at different heights to reduce a force transmitted to the needle holding unit  200 , thus rotating in order to adjust the locking steps  330 . 
     That is, the second grooves  312  may be modified to rotate the plurality of locking steps  330 , thus controlling the intensity of force transmitted to the needles  100 . As shown in  FIG. 20 , as the locking steps  330  rotate, the heights of the locking steps  330  change. The intensity of force generated by the drive unit  300  is adjusted by rotating the locking steps  330 , and then the force is transmitted to the needles  100 . 
     Moreover, as shown in  FIG. 21 , a ‘U’-shaped adjusting member is inserted into the first coupling part, and the skin support member  700  into which the assembly  140  is inserted is fitted into and assembled with the second coupling part. When the assembling operation is conducted in this way, force is transmitted to the assembly  140  by the drive unit  300 , and the assembly  140  is moved downward by the transmitted force. Here, since the assembly  140  includes the needles  100 , the needles  100  are inserted into the skin by the downward movement of the assembly  140 . 
     When the assembly  140  provided in the skin support member  700  moves downward and the ‘U’-shaped adjusting member is fitted into the second coupling part, the ‘U’-shaped adjusting member is stopped by the internal casing within a range wherein the needles are not caught, thus controlling the forward moving force of the drive unit  300 . 
     In a related context, a component substituting for the adjusting member  320  or an insertion limiting member  1300  cooperating with the adjusting member  320  may be further provided. The insertion limiting member  1300  functions to adjust the depth to which the needles  100  are inserted into the skin. One side of the insertion limiting member  1300  may be supported by the skin, while the other side may be supported by a casing  1000  as shown in  FIG. 22  or  23 . Meanwhile, one side of the insertion limiting member  1300  may be supported by the skin, while the other side may be supported by the skin support member  700  as shown in  FIG. 24 . The replacement of the insertion limiting member  1300  is possible.  FIG. 31  shows another type of insertion limiting member  1300 . Meanwhile, referring to  FIGS. 33 and 34 , the insertion limiting member  1300  may be provided with a cooling medium passage  1350  through which a cooling medium flows. The cooling medium passage  1350  is provided with a cooling medium inlet  1320  into which the cooling medium is introduced, and with a cooling medium outlet  1340 . Various media including water or air may be used as the cooling medium. After the cooling medium fed into the cooling medium inlet  1320  flows through the cooling medium passage  1350 , the cooling medium is discharged through the cooling medium outlet  1340 . The cooling medium serves to cool the insertion limiting member  1300 , thus alleviating the pain of a patient. Holes besides the cooling medium inlet  1320  or the cooling medium outlet  1340  of the cooling medium passage  1350  may be appropriately closed by stoppers. 
     After the electromagnetic wave transmitting unit  400  receives electromagnetic waves from the exterior through a cable, the electromagnetic wave transmitting unit  400  transmits the electromagnetic waves to the needles  100 . 
     Meanwhile, the skin treating device  10  according to an embodiment of the invention may further include a cavity body  500 . That is, the skin treating device  10  may include the plurality of needles  100 , the needle holding unit  200 , the drive unit  300 , the electromagnetic wave transmitting unit  400 , and the cavity body  500 . 
     Since the needles  100 , the needle holding unit  200 , the drive unit  300 , and the electromagnetic wave transmitting unit  400  are the same as those of the above-mentioned embodiment, the detailed description thereof will be omitted, and only the cavity body  500  will be described. 
     The cavity body  500  includes a third coupling part to allow the needle holding unit  200  to be fitted into and assembled with the third coupling part, and a fourth coupling part to allow the adjusting member  320 , which is for adjusting the depth of the needles  100  inserted into the skin, to be assembled therewith. The third and fourth coupling parts have the same function as the first and second coupling parts. 
     For example, as shown in  FIG. 25B , the cavity body  500  is provided with third grooves  531  and fourth grooves  532 . The needle holding unit  200  is fitted into the third grooves  531 . The third grooves  531  correspond to the first grooves  311 . The adjusting member  320  for adjusting the depth of the needles  100  inserted into the skin is inserted into the fourth grooves  532 . The fourth grooves  532  correspond to the second grooves  312 . The third and fourth grooves  531  and  532  are integrally formed in the cavity body  500 . The third and fourth grooves  531  and  532  may be formed separately from the cavity body  500  and then be assembled with the cavity body  500 . A force is exerted on the needle holding unit  200  assembled with the cavity body  500  so that the needles  100  are inserted into the skin. The third and fourth coupling parts may be designed to have construction different from that of  FIG. 25B . 
     The cavity body  500  is open at one side thereof so that the drive unit  300  is fitted therein. A water circulating structure is provided on a side surface of the cavity body  500  which is in contact with the drive unit  300 , thus cooling heat generated from the drive unit  300 . 
     For example, as shown in  FIGS. 25A and 25B , one side of the cavity body  500  is open so that the drive unit  300  is fitted and inserted therein. Referring to  FIG. 26B  that is the sectional view taken along line A-A′ of  FIG. 26A , the water circulating structure is provided on the side surface of the cavity body  500  which is in contact with the drive unit  300 . The drive unit  300  includes an inlet  510  into which water is introduced, and an outlet  520  through which water is discharged. After water injected through the inlet  510  has circulated, the water is discharged through the outlet  520 . 
     Further, as shown in  FIG. 27 , the cavity body  500  is provided with a thermoelement  540 . The thermoelement  540  functions to cool the drive unit  300  which emits heat. The thermoelement  540  is constructed so that a portion which is in contact with the drive unit  300  is maintained at a low temperature and a portion which is opposite to the drive-unit contact portion is maintained at a higher temperature. The thermoelement  540  is provided on a side surface of the cavity body  500  on which the inlet  510  and the outlet  520  are formed. 
     Moreover, an air cooling structure may be used to substitute for the water circulating structure. Preferably, the air cooling structure is formed such that external cold air is introduced into the inlet  510  and then is discharged through the outlet  520  to the outside. 
     Preferably, as shown in  FIG. 28 , the casing  1000  is further provided to protect the plurality of needles  100 , the needle holding unit  200 , the drive unit  300 , the electromagnetic wave transmitting unit  400 , and the cavity body  500 . 
     Further, as shown in  FIG. 28 , the CPU  1100  is preferably provided to process all data for operating the skin treating device according to an embodiment of the invention. The data processed by the CPU  1100  includes data on the lifespan of the drive unit  300 , data on the needles  100  (the number of needles and the length of needles), data on the electromagnetic wave voltage, and data on the time that the electromagnetic waves are output. 
     Especially, when the data on the needles  100  transmitted to the memory unit  900  is identical to the data on the needles  100  stored in the memory unit  900 , the device works. In contrast, when the transmitted data is not identical with the stored data, the device does not work. 
     Moreover, the CPU  1100  performs control such that, when a characteristic number received from the memory unit  900  is different from an input characteristic number, the device does not work. If the received characteristic number is identical to the input characteristic number, a counting operation is performed to reach a preset time corresponding to the lifespan. After the preset time has passed, the operation of the assembly  140  is stopped. 
     Further, the CPU  1100  checks the lifespan of the needles  100  by counting the number of times the needles  100  have been inserted into the skin. Preferably, the CPU  1100  may check the lifespan of the needles  100  by counting the number of times the drive unit  300  transmits force to the needles  100 . The CPU  1100  may perform a counting operation by detecting the movement of the needles  100  using a sensor. As such, the CPU  1100  may check the lifespan of the needles  100  in various methods. The reason why the CPU  1100  checks the lifespan of the needles  100  is because the needles  100  which are bent, broken or worn out at ends thereof must be replaced with new ones. 
     The memory unit  900  may be directly connected to the CPU  1100 . However, a connector  1200  may be further provided to allow the memory unit  900  to be smoothly replaced by another one. 
     In a related context, as shown in  FIG. 29 , the casing  1000  is provided with a cold air injection nozzle  1400 . The cold air injection nozzle  1400  functions to cool skin which is to be treated, before or after the needles  100  have been inserted. The cold air injection nozzle  1400  sprays cold air, fed from the outside of the casing  1000  to a cold air inflow passage (not shown), onto the skin under regular pressure. The cold air injection nozzle  1400  protrudes from the casing  1000  toward the skin. The cold air sprayed from the cold air injection nozzle  1400  cools the skin, thus removing the pain and aiding in healing a wound. 
     Referring to  FIG. 35 , according to another embodiment of the invention, each needle  100  is provided with a drug feeding tube  105 . The drug feeding tube  105  extends in the longitudinal direction of the needle  100  in such a way as to pass from the upper end to the lower end of the needle  100 . In the state in which each needle  100  has been inserted into the skin, the drug feeding tube  105  feeds a required drug into the skin. One end of a drug supply passage  1530  is connected to the upper portions of the needles  100  to supply the drug to only some of the needles  100 . Transmitting members  410  are connected to the upper portions of the remaining needles  100  to transmit electromagnetic waves from the electromagnetic wave transmitting unit  400  to the needles  100 . That is, a drug is not supplied to the needles  100  equipped with the transmitting members  410 . The other end of the drug supply passage  1530  is connected to a drug feeding unit  1500 . The drug feeding unit  1500  is a kind of syringe pump and has a piston  1510  which is compressed. The drug feeding unit  1500  contains a drug  1520  therein. The piston  1510  may be constructed to be subjected to a pressure by a power means, for example, a motor, pneumatic means, or hydraulic means. The skin treating device constructed as shown in  FIG. 35  injects the drug into one part of the skin and transmits the electromagnetic waves to the other part, with needles  100  being inserted into the skin, thus enabling the effective treatment of the skin. 
     Although the various embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.