Abstract:
Disclosed is an auto folder type mobile phone. More specifically, an auto folder type mobile phone for automatically opening/closing the folder by means of the driving means, the auto folder type mobile phone capable of preventing noise generation by eliminating the portion where direction of applied force is reversed instantly, upon opening/closing of the folder, is provided.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates generally to an auto folder type mobile phone for opening/closing a folder automatically, and more particularly to an auto folder type mobile phone for opening/closing the folder at a stable position by controlling a position of the folder and correcting a phase difference resulting from load and unstableness of the driving apparatus.  
           [0003]    2. Description of the Related Art  
           [0004]    Generally, a mobile phone or a cellular phone is a terminal for a mobile communication service that can be used in a uniform circle within a service area by making a part of customer&#39;s lines wireless. While an existing service is used at a limited area using line numbers, the mobile phone can be used regardless of a place using a logical personal number.  
           [0005]    This mobile phone is easily portable and convenient for use, and so its demand increases tremendously, and is miniaturized and has multi-functions in order to fulfill customer&#39;s various desires.  
           [0006]    Normally, the mobile phone is classified into a bar type where number (function) buttons are exposed outside, a flip type having a cover for shielding the buttons, and a folder type where the body is folded in halves, the folder type mobile phone being popular following the trend of miniaturization.  
           [0007]    Generally, in the folder type mobile phone, the folder is hinged to allow the folder to rotate toward/from the body, and its opening/closing is made by a rotation of the folder in a direction or a reverse direction round a center of the hinge.  
           [0008]    However, the related folder type mobile phone is disadvantageous in that when a user wants to open/close the folder, he should operate the folder by one hand with the other hand holding the body because of a heavy weight of the folder.  
           [0009]    Suggested is a mobile phone for more easily opening/closing the folder while solving the problem, and its typical embodiment is an auto folder type mobile phone using a driving apparatus.  
           [0010]    [0010]FIG. 1 is a perspective view of showing an appearance of a general auto folder type mobile phone.  
           [0011]    As shown in the figure, the auto folder type mobile phone comprises a body  10  and a folder  20 . The body has a button  11  for inputting normal various functions and numbers, and a mic  12 . Although not shown in this figure, various components and circuits are included for a telephone communication, and a battery pack  13  for power supply is included detachably.  
           [0012]    Additionally, the folder  20  includes a display window  21 , which shows information about the telephone communication and function, a speaker  22 , various components and circuits.  
           [0013]    In this mobile telephone constructed as above, the folder  20  is opened/closed automatically from the body  10  by an operation signal of a switch sw, which is positioned at a side of the body  10 .  
           [0014]    [0014]FIG. 2 is an exploded perspective view of showing main parts of the related auto folder type mobile phone, and FIG. 3 to FIG. 5 are cross sectional views of sequentially showing operations of a hinge shaft and a hinge cam in the related auto folder type mobile phone. FIG. 6 is a view of showing directions of forces at a mutual operation surface of the hinge shaft and the hinge cam in the related auto folder type mobile phone.  
           [0015]    As shown in the figures, the body  10  is provided with fixing units  100  projected, which have holes faced each other at a specific interval. Between the fixing units is inserted a pipe shaped housing  200  which is projected from the folder  20 .  
           [0016]    In the fixing unit  100  and the housing  200  are positioned a driving means and a dynamic transfer means for an automatic opening/closing by the switch sw signal.  
           [0017]    The driving means comprises a motor  300  that is operated by the switch sw signal, and a speed reducer  310  connected to an output end of the motor to decrease a rotation rate and to increase a torque by preventing, a reversing movement. The dynamic transfer means comprises a hinge shaft  400  connected to an output end of the speed reducer  310  to work integrally with the speed reducer, a hinge cam  410  engaged with the hinge shaft  400  and positioned in the fixing unit  100 , and a elastic body  450  applying a elastic force to the hinge cam  410  and the fixing unit  100 .  
           [0018]    A numeral  210  is a bracket for fixing the housing  200  to the folder.  
           [0019]    The above related auto folder type mobile phone is disadvantageous in that the opening/closing operation of the folder  20  generated noise because of a mechanism between the hinge cam  410  and the hinge shaft  400  that is mounted in the housing  200  when the housing  200  is engaged with the fixing unit  100 . This phenomenon is more serious specially when the folder  20  is opened/closed manually.  
           [0020]    This phenomenon is because of Backlash of the speed reducer  310  for increasing the torque. That is, this is shown because a direction of force applied to an operation surface is instantly reversed when a projected part of the hinge shaft  400  rotates across a concaved part of the hinge cam  410 , due to the backlash.  
           [0021]    As shown in the drawings, a projection  411  on edges of the hinge cam  410  is provided with forces in the left and right direction, and these forces are shown in a horizontal direction.  
           [0022]    In more detail with respect to FIG. 6, when the hinge cam  410  is positioned at an “a” position, forces F 1  and F 2  acts in directions as shown, and when the hinge cam  410  rotates in a clockwise to a “b” position, the operation surface is in a reverse direction, thus making the forces to be F 3  and F 4 , respectively. The force F 1 , F 2  and the forces F 3 , F 4  respectively have a same magnitude and have opposite directions to each other. However, in case the force&#39;s directions are reversed as mentioned above, noise is generated due to the foregoing backlash. Although this noise is not a serious defect that affects a commodity vale of the auto folder type mobile phone, it causes an uncomfortable feeling to users, thus decreasing reliance of the phone.  
         SUMMARY OF THE INVENTION  
         [0023]    Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an auto folder type mobile phone for eliminating a part where the direction of the force of the operation surface is reversed instantly when the projected part of the hinge shaft passes an concave part of the hinge cam, thus eliminating noise.  
           [0024]    That is, this object is to disperse the force in order to prevent the forces from acting in the rotation direction and so decreases change of the forces in the rotation direction to decrease noise resulting from a connection.  
           [0025]    In order to accomplish the above object, the present invention provides an auto folder type mobile phone including: a pair of fixing units, each of which is positioned at one end of a body, with holes facing each other; a cylinder shaped housing, connected with a folder, positioned between the pair of the fixing units, and its both sides are opened; a driving means, mounted in an interior of the housing, for selectively generating a rotation force; a hinge shaft, whose one end is connected with the driving means, for being rotated integrally with the driving means, and whose other end has a projected connection part; and a hinge cam provided to an interior of the fixing units, whose one end receives a supporting force of the elastic body, for being connected with the connection part, wherein the one end has a concaved central part and a mountain shape of curved edges in both sides, so that force applied to the operation surface of the hinge shaft, is dispersed in an axial direction and a radial direction.  
           [0026]    It is an preferable aspect of the present invention that the connection part of the hinge shaft is a triangular prism shape of a pentahedron, and its edge forms a curved surface.  
           [0027]    It is another preferable aspect of the present invention that the connection part of the hinge shaft and a portion connected with the hinge cam are formed for being engaged with each other by corresponding size.  
           [0028]    It is another preferable aspect of the present invention that the driving means comprises a motor connected to a switch, for generating rotational force in forward and reverse directions, and a speed reducer connected to an output end of the motor, for preventing reversing movement, reducing rotation rate.  
           [0029]    It is another preferable aspect of the present invention that the driving means receives an operation signal from a switch provided to one side of the body, for generating rotational force in forward and reverse directions.  
           [0030]    It is another preferable aspect of the present invention that the elastic body is provided to an interior of the fixing units, one end of which is fixed in one side of the interior of the fixing units, the other end of which applies elastic force toward the hinge shaft, and the elastic body is a coil spring transformed elastically so that the hinge cam is possibly rotated by external force applied to the folder.  
           [0031]    It is another preferable aspect of the present invention that the motor is fixed in an interior of the housing, for operating integrally.  
           [0032]    It is another preferable aspect of the present invention that the speed reducer is connected with one end of the hinge shaft, for delivering decreased rotational force.  
           [0033]    According to another embodiment of the present invention provides an auto folder type mobile phone including: a pair of fixing units, each of which is positioned at one end of a body, with holes facing each other; a cylinder shaped housing, connected with a folder, positioned between the pair of the fixing units, and its both sides are opened; a driving means, mounted in an interior of the housing, for selectively generating a rotation force; a hinge shaft provided to an interior in one side of the fixing unit, for being moved elastically to a side of the housing, influenced by supporting force from the elastic body, and whose end portion extended to a housing side, has a connection part of a projected shape; a hinge cam, one end of which is connected with the driving means, for being rotated integrally, the other end of which is elastically connected with the hinge shaft, wherein the other end has a concaved central part and a mountain shape of curved edges at both sides so that force applied to the operation surface of the hinge shaft can be dispersed in a radial direction and an axial direction. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0034]    The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:  
         [0035]    [0035]FIG. 1 is a perspective view of showing an appearance of a general auto folder type mobile phone;  
         [0036]    [0036]FIG. 2 is an exploded perspective view of showing main parts of the related auto folder type mobile phone;  
         [0037]    [0037]FIG. 3 to FIG. 5 are cross-sectional views of sequentially showing operations of a hinge shaft and a hinge cam in the related auto folder type mobile phone;  
         [0038]    [0038]FIG. 6 is a view of showing directions of forces at a mutual operation surface of the hinge shaft and the hinge cam in the related auto folder type mobile phone;  
         [0039]    [0039]FIG. 7 is an exploded perspective view of showing main parts of the related auto folder type mobile phone;  
         [0040]    [0040]FIG. 8 to FIG. 10 are cross-sectional views of sequentially showing operations of a hinge shaft and a hinge cam in the related auto folder type mobile phone;  
         [0041]    [0041]FIG. 11 is a view of showing the hinge cam in an “A” direction of FIG. 7;  
         [0042]    [0042]FIG. 12 is an illustrative view of showing the directions of the forces on the operation surface of the hinge shaft and the hinge cam in the auto folder type mobile phone of the present invention;  
         [0043]    [0043]FIGS. 13 through 15 are cross-sectional views of sequentially showing mutual operations of a hinge cam and a hinge shaft according to another embodiment of the auto folder type mobile phone of the present invention; and  
         [0044]    [0044]FIG. 16 is a drawing schematically showing directions of force on an operation surface of a hinge cam and a hinge shaft according to another embodiment of the auto folder type mobile phone of the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0045]    A preferable embodiment of the auto folder type mobile phone of the present invention is explained in detail with respect to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.  
         [0046]    [0046]FIG. 7 is an exploded perspective view of showing main parts of the related auto folder type mobile phone. FIG. 8 to FIG. 10 are cross-sectional views of sequentially showing operations of a hinge shaft and a hinge cam in the related auto folder type mobile phone.  
         [0047]    [0047]FIG. 11 is a view of showing the hinge cam in an “A” direction of FIG. 7, and FIG. 12 is an illustrative view of showing the directions of the forces on the operation surface of the hinge shaft and the hinge cam in the auto folder type mobile phone of the present invention.  
         [0048]    The auto folder type mobile phone according to a preferable embodiment of the present invention has an appearance similar to the general related auto folder type mobile phone of FIG. 1, and a similar cross section to the FIG. 3 to FIG. 5. However, in this present invention, the shape of the hinge shaft and the hinge cam, which are the driving apparatuses for opening/closing the folder automatically, and the force direction applied to the operation surface in case of the rotation are different from the related art.  
         [0049]    That is, a structure for driving the folder  20  according to the present invention is well shown in the cross sectional views of the fixing unit  15  and the housing  25  of FIG. 7.  
         [0050]    The driving apparatus of the folder  20  of the mobile phone of the present invention comprises a driving means fixed in the housing  20  to generate a driving force and a dynamic transfer means including a elastic member for acting a elastic force and a pair of members selectively connected to the driving means. The driving means is formed integrally at a side of the folder  20  or is positioned in the cylinder shaped housing  25  that is fixed by the bracket, and the driving means generates a driving force for rotating the folder  20 , and comprises normal forward reverse motor  30  and a speed reducer  35 .  
         [0051]    The motor  30  is operated by a signal of the switch sw positioned at a side of the body, and is supplied with a power from a battery pack  13  mounted on the mobile phone, according to the switch sw signal and generates a specific rotation force in a forward/reverse direction.  
         [0052]    Additionally, an output end of the motor  30  is provided with a speed reducer  35 , and the speed reducer  35  is a combination of normal gears to decrease the rotation force of the motor  30  at a uniform rate and increase a torque while preventing a reversing movement.  
         [0053]    In the driving means constructed as above, the rotation force generated by the motor  30  is decreased by the speed reducer  35  to rotate the output end.  
         [0054]    Meanwhile, normal small motor  30  and speed reducer  35  can be used for the driving means as in the present invention, and various driving devices can be also used as long as they generate stable rotation forces in a forward/reverse direction in order to drive the folder  20  and simultaneously prevent the reversing movement.  
         [0055]    The dynamic transfer means comprises a hinge shaft  40  and a hinge cam  45 , and as shown in the drawing, the hinge shaft  40  is connected to the output end of the speed reducer  35 , is rotated integrally with the speed reducer. The hinge shaft  40  is positioned in the housing  25 , and has tapers at its both sides to make its central part projected, and the hinge cam  45  is positioned in the fixing unit  15 , and has a taper formed inside in order to make its central part concaved in an opposite direction to the projected part of the hinge shaft  40 .  
         [0056]    The hinge shaft  40  and the hinge cam  45  constructed as above is applied with the elastic force of the elastic body to form a fixing part by engaging with each other in case the driving force of the driving means is transferred. The shaft and the cam are detached in case an external force is applied to the folder  20  during an automotive mode operation or during a manual opening/closing of the folder  20 .  
         [0057]    That is, a coil shaped elastic body  50  is positioned in a fixing unit  15  of the pair of the fixing units  15  that is integrally formed at a side of the body  10 . One end of the elastic body  50  is fixed to an internal side of the fixing unit  15 , and the other end is contacted with a surface of the hinge cam  45  to perform the elastic force. This elastic body  50  keeps a larger elastic force than the driving force generated by the driving means, and applies the elastic force to the hinge shaft  40  and the hinge cam  45  to make them selectively engaged or detached.  
         [0058]    In more detail, the elastic body  50  applies a larger force to the hinge shaft  40  and the hinge cam  45  than the driving means in case the folder  20  is opened or closed on the basis of the body  10  by the driving means, and so the elastic keeps the engagement state of the hinge shaft  40  and the hinge cam  45  and causes a elastic transformation to allow the hinge shaft  40  and the hinge cam detached in case of opening/closing the folder  20  manually.  
         [0059]    Meanwhile, the hinge shaft  40  and the hinge cam  45  among the components of the dynamic transfer means is a substantial characteristic of the present invention, and a detail of the characteristic is as follows.  
         [0060]    As shown in FIG. 7, a part of the hinge shaft  40  contacted with the hinge cam  45  is approximately a triangular prism shape of a pentahedron, and its edge part forms a smooth surface. Additionally, a surface of the hinge cam  45  contacted with the hinge shaft  40  has, on its edge, a projection that has more gently curved edges in comparison with the related construction. That is, the hinge cam  45  has a concaved central part and mountain shaped edges at both sides, and so force applied to the operation surface with the hinge shaft  40  can be dispersed in a radial direction and in an axial direction of the housing  25  when the cam rotates engaged with the hinge shaft  40 .  
         [0061]    The operation of the auto folder type mobile phone of the present invention constructed as above is as follows.  
         [0062]    First, when a user rotates the folder  20  in a forward direction or a reverse direction to/from the body  10  in order to manually close/open the folder, the housing  25  rotates in the forward/reverse direction according to the rotation of the folder  20 .  
         [0063]    The rotation force applied to the housing  25  is larger than the elastic force generated by the elastic body  50 , and so the hinge shaft  40  and the hinge cam  45  are slipped and separated from each other. That is, the hinge shaft  40  is rotated integrally with the housing  25 , and so the hinge cam  45  goes back and compresses the elastic  50 , thus opening/closing the folder.  
         [0064]    Additionally, in case the switch sw is operated that is positioned at a side of the body  10  in order to manually open the folder  20 , the motor and the speed reducer  35  generates a driving force by the signal of the switch.  
         [0065]    Subsequently, the hinge shaft  40  that is connected to the output end of the speed reducer  35  rotates, and the hinge cam  45  that is connected to the hinge shaft  40  rotates by a uniform angle to compress the elastic body  50 , thus making the elastic body move horizontally by a restoration force of the elastic body  50  at the operation of the driving means.  
         [0066]    That is, the hinge shaft  40  in the housing  25  is applied with the rotation force of the driving means in the engagement state with the hinge cam  45 , and the elastic force of the elastic body  50  is larger than the driving force of the driving means, and so the hinge shaft  40  and the hinge cam  45  maintains the mutual engagement, thus rotating the driving means.  
         [0067]    In this case, the hinge shaft  40  in the housing  25  rotates in the hinge cam  45  without going over a top when the shaft crosses the hinge cam  45 , and so a direction of the force is dispersed not in a rotation direction of the hinge shaft  40 , but in an axial direction and a radial direction of the housing  25 , thus decreasing noise.  
         [0068]    That is, the rotation movement is transferred and however an external force due to the elastic force in the axial direction is blocked, and so a load transferred to the axis can be reduced to prevent the elastic force of the elastic force  50  from being transferred to the speed reducer  35 .  
         [0069]    Accordingly, the “backlash” phenomenon can be prevented, thus increasing reliance and performance of the phone, and decreasing noise.  
         [0070]    Meanwhile, also in case the folder  20  is closed and a load is applied to the folder  20 , the folder  20  is opened/closed in a same way as the foregoing, thus decreasing noise.  
         [0071]    [0071]FIGS. 13 through 15 are cross-sectional views of sequentially showing mutual operations of a hinge cam and a hinge shaft according to another embodiment of the auto folder type mobile phone of the present invention, and FIG. 16 is a drawing schematically showing directions of force on an operation surface of a hinge cam and a hinge shaft according to another embodiment of the auto folder type mobile phone of the present invention. In the following, description will be made with reference to FIG. 7 and the same reference numerals is used for the same parts except the hinge cam and the hinge shaft.  
         [0072]    As shown in FIG. 7, the auto folder type mobile phone of the present embodiment, has the same construction as the mobile phone of the embodiment previously described except the dynamic transfer means in which the hinge cam  45 ′ and the hinge shaft  40 ′ are changed in their positions.  
         [0073]    Namely, according to another embodiment of the auto folder type mobile phone of the present invention, the hinge cam  45 ′ is connected with the driving means installed in the side of the housing, and the hinge shaft  40 ′ is connected, within one fixing unit corresponding to the housing, with the hinge cam  45 ′, influenced by supporting force from the elastic body.  
         [0074]    Here, the driving means is formed integrally at a side of the folder  20  or is positioned in the cylinder shaped housing  25  that is fixed by the bracket, and the driving means generates a driving force for rotating the folder  20 , and comprises normal forward reverse motor  30  and a speed reducer  35 .  
         [0075]    The motor  30  is operated by a signal from the switch sw positioned at a side of the body, and generates specific rotation force in a forward/reverse direction, provided with power from a battery pack  13  mounted on the mobile phone, according to a signal from the switch sw.  
         [0076]    Additionally, an output end of the motor  30  is provided with a speed reducer  35 , and the speed reducer  35  is a combination of normal epicyclic gears to decrease the rotation force of the motor  30  at a predetermined rate and increase a torque while preventing a reversing movement. In the driving means constructed as above, the rotation force generated by the motor  30  is decreased by the speed reducer  35  to rotate the output end with torque increased.  
         [0077]    The dynamic transfer means comprises the hinge shaft  40 ′ and the hinge cam  45 ′, and as shown in the drawing, the hinge cam  45 ′ is connected to the output end (not shown) of the speed reducer  35 , and is rotated integrally with the speed reducer. The hinge shaft  40 ′ has a taper formed inside in order to make its central part concaved. Additionally, the hinge shaft  40 ′ is positioned in the fixing unit  15  corresponding to one side of the housing on which the hinge cam  45 ′ is installed, and has a taper on its both sides with its central part projected for being engaged with the hinge cam  45 ′.  
         [0078]    The hinge shaft  40 ′ and the hinge cam  45 ′ having the foregoing construction is influenced by the elastic force of the elastic body  50  having a form of a coil spring, to form a fixing part by being engaged with each other in case that the driving force of the driving means is transferred. The shaft and the cam are detached in case that external force is applied to the folder  20  during an automotive mode operation or during a manual opening/closing of the folder  20 .  
         [0079]    More specifically, the elastic body  50  applies a larger force to the hinge cam  45 ′ and the hinge shaft  40 ′ than the driving means in case the folder  20  is opened or closed with respect to the body  10  by the driving means, so that the engagement state of the hinge shaft  40 ′ and the hinge cam  45 ′ is maintained. In case of opening/closing the folder  20  manually, elastic transformation is generated so that the hinge cam  45 ′ and the hinge shaft  40 ′ are possibly detached each other.  
         [0080]    Here, the hinge cam  45 ′ and the hinge shaft  40 ′ are substantial elements having characteristics of the present invention. The characteristics thereof will be described in the following.  
         [0081]    Also, a part of the hinge shaft  40 ′ connected with the hinge cam  45 ′ is approximately a triangular prism shape of a pentahedron, and its edge part forms a curved surface.  
         [0082]    Additionally, one surface of the hinge cam  45 ′ connected with the hinge shaft  40 ′ has, on its edge, a projection that has more gently curved edges, compared with the construction of the related art.  
         [0083]    Namely, the hinge cam  45 ′ has a concaved central part and a mountain shape of edges at both sides so that force applied to the operation surface of the hinge shaft  40 ′ can be dispersed in a radial direction and an axial direction of the housing  25  when the hinge cam  45 ′ rotates, engaged with the hinge shaft  40 ′.  
         [0084]    The operation of the auto folder type mobile phone of the present invention having the foregoing construction, will be described in the following.  
         [0085]    First of all, when a user rotates the folder  20  in a forward direction or a reverse direction with respect to the body  10  in order to manually close/open the folder, the housing  25  rotates integrally in the forward/reverse direction according to the rotation of the folder  20 .  
         [0086]    Here, the rotation force applied to the housing  25  is larger than the elastic force generated by the elastic body  50 , so that the hinge shaft  40 ′ and the hinge cam  45 ′ are slipped and separated from each other.  
         [0087]    Namely, the hinge cam  45 ′ is rotated integrally with the housing  25 , whereby the hinge shaft  40 ′ goes back, compressing the elastic body  50 , and the folder is possibly opened and closed.  
         [0088]    Additionally, in case that the switch sw positioned at one side of the body  10 , is operated in order to automatically open the folder  20 , the motor and the speed reducer  35  generate a driving force by the signal from the switch.  
         [0089]    Subsequently, the hinge cam  45 ′ is connected with the output end of the speed reducer  35  and rotated integrally, and the hinge shaft  40 ′ connected with the hinge cam  45 ′ rotates by a predetermined angle, thereby compressing the elastic body  50 , so that the hinge shaft  40 ′ is moved horizontally by a restoration force of the elastic body  50  upon operation of the driving means.  
         [0090]    Namely, the hinge cam  45 ′ within the housing  25  is given the rotation force from the driving means in the state of mutual engagement with the hinge shaft  40 ′ arranged in facing direction, and the elastic force of the elastic body  50  is larger than the driving force from the driving means, so that the hinge cam  45 ′ and the hinge shaft  40 ′ maintain the mutual engagement, and resultantly, the driving means is rotated.  
         [0091]    At the moment, the hinge shaft  40 ′ rotates in an interior of the hinge cam  45  without going over a top when the hinge shaft  40 ′ crosses the hinge cam  45 ′, so that a direction of the force is dispersed not in a rotation direction of the hinge cam  45 ′, but in an axial direction and a radial direction of the housing  25 , whereby noise is decreased.  
         [0092]    Namely, rotational movement is transferred, but transfer of external force due to elastic force to the axial direction is blocked, so that the load transferred to the axis could be reduced and elastic force due to elastic body  50  is not delivered to the speed reducer  35 , which is the driving means. Therefore, backlash phenomenon is prevented and resultantly, improvement in reliability and performance, and reduction in noise are expected.  
         [0093]    In the meantime, in case that the load is applied to the folder  20  while the folder  20  is closed, the folder  20  is opened/closed in the same way as the foregoing, and noise is decreased.  
         [0094]    As is apparent from the foregoing, the auto folder type mobile phone of the present invention, resolve the existing problem that the product is devaluated due to “clatter” noise, thereby achieving improvement in reliability, noise reduction, and performance improvement as well as remarkably improving product quality.  
         [0095]    While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.