Patent Publication Number: US-2019184425-A1

Title: Linear actuator

Description:
TECHNICAL FIELD 
     The present invention relates to a linear actuator in which a movable element vibrates in a direction of an axis line, inside a case used as a stationary element. 
     BACKGROUND ART 
     As a device for notifying of information by way of a vibration, there is proposed a liner actuator that includes a movable element equipped with a plurality of permanent magnets in a direction of an axis line (a vibrating direction), and a stationary element having a coil placed around the permanent magnets (refer to Patent Document 1). 
     CITATION LIST 
     Patent Literature 
     Patent Document 1: Japanese Unexamined Patent Application Publication No. 2016-101075 
     SUMMARY 
     Technical Problems 
     Unfortunately, according to a configuration described in Patent Document 1; information is transferred to a user holding a linear actuator, only by use of a vibration, so that there exists a problem that a use is restricted. 
     With the issue described above being taken into consideration, it is an objective of the present invention to provide a linear actuator with which information can be transferred to a user by way of a vibration and a sound. 
     Solutions to Problems 
     In order to solve the issue described above, a linear actuator according to the present invention includes: a movable element; a stationary element provided with a case in which the movable element is housed; and a magnetic drive mechanism that drives the movable element in a direction of an axis line; wherein, the case has a bottom plate part, provided with a sounding hole for discharging a sound in accordance with a vibration of the movable element in the direction of the axis line, at either one side or the other side in the direction of the axis line. 
     According to the present invention; at a time when the movable element is vibrated in the direction of the axis line by the magnetic drive mechanism, a vibration is transferred to a user. Accordingly, information can be transferred by way of the vibration, while a form of the vibration is shifted in response to the information to be transferred. In the meantime, the case includes the bottom plate part provided with the sounding hole, at the end part of either the one side or the other side in the direction of the axis line, so that a pressure change can be output as an audible level sound from the sounding hole, the pressure change being in accordance with a vibration of the movable element in the direction of the axis line. Accordingly, the information can also be transferred by way of the sound. Therefore, a use of the linear actuator can be expanded. 
     According to the present invention; adopted may be a mode, in which the bottom plate part is perpendicular to the direction of the axis line. 
     According to the present invention; adopted may be a mode, in which the magnetic drive mechanism includes permanent magnets provided in the movable element and coils provided in the stationary element; the permanent magnets are so placed as to be stacked in plurality, in the direction of the axis line; the coils are placed in plurality along the axis line; and within the plurality of permanent magnets, permanent magnets positioned next to each other in the direction of the axis line are placed in such a way that the same-polarity parts face each other. According to the mode, density of magnetic flux, generated from a location between the permanent magnets positioned next to each other in the direction of the axis line, is high. 
     Therefore, a great thrust power can be generated with the movable element; and moreover in the case of enhancing a thrust power, the number of permanent magnets can be reduced. Accordingly, an increase of a dimension of the movable element in the direction of the axis line can be controlled. 
     According to the present invention; adopted may be a mode, in which three or more permanent magnets are stacked in the direction of the axis line, in the movable element. 
     According to the present invention; adopted may be a mode, in which a viscous elastic member is provided between the movable element and the stationary element. According to the mode, at a time when the movable element vibrates, resonance of the movable element can be suppressed. 
     According to the present invention; adopted may be a mode, in which the viscous elastic member is provided at a plurality of locations being separate in the direction of the axis line, while at the locations, the movable element and the stationary element face each other in a direction perpendicular to the direction of the axis line. According to the mode, the movable element can appropriately be supported by the viscous elastic member, without using any spring component, even though the dimension of the movable element in the direction of the axis line is great. 
     Effect of the Invention 
     According to the present invention; at a time when the movable element is vibrated in the direction of the axis line by the magnetic drive mechanism, a vibration is transferred to a user. Accordingly, information can be transferred by way of the vibration, while a form of the vibration is shifted in response to the information to be transferred. In the meantime, the case includes the bottom plate part provided with the sounding hole, at the end part of either the one side or the other side in the direction of the axis line, so that a pressure change can be output as an audible level sound from the sounding hole, the pressure change being in accordance with a vibration of the movable element in the direction of the axis line. Accordingly, the information can also be transferred by way of the sound. Therefore, a use of the linear actuator can be expanded. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  includes perspective views of a linear actuator to which the present invention is applied. 
         FIG. 2  includes cross-sectional views of the linear actuator shown in  FIG. 1 . 
         FIG. 3  is an exploded perspective view of the linear actuator shown in  FIG. 1 , wherein a case is dismounted. 
         FIG. 4  is an exploded perspective view of the linear actuator shown in  FIG. 1 , wherein components placed inside the case are disassembled. 
         FIG. 5  is an exploded perspective view of the linear actuator shown in  FIG. 1 , wherein an external yoke is dismounted from an outside part of coils. 
         FIG. 6  is an exploded perspective view of the linear actuator shown in  FIG. 1 , wherein permanent magnets and the like are dismounted from an inside part of the coils. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Preferred embodiments of the present invention are explained below with reference to the drawings. In an explanation described below, an axis line of a movable element  6  is referred to as ‘L’; and in an extending direction of the axis line L (a vibrating direction of the movable element  6 ), one side is provided with a symbol ‘L 1 ’, and the other side is provided with a symbol ‘L 2 ’ in the explanation. 
     (General Configuration) 
       FIG. 1  includes perspective views of a linear actuator  1  to which the present invention is applied; wherein  FIG. 1( a )  and  FIG. 1( b )  are a perspective view in which the linear actuator  1  is viewed from one side L 1 , and another perspective view in which the linear actuator  1  is viewed from the other side L 2 , respectively.  FIG. 2  includes cross-sectional views of the linear actuator  1  shown in  FIG. 1 ; wherein  FIG. 2( a )  and  FIG. 2( b )  are a longitudinal cross-sectional view in which the linear actuator  1  is sectioned along the axis line L, and a lateral cross-sectional view in which the linear actuator  1  is sectioned along a plane perpendicular to the axis line L. 
     The linear actuator  1  shown in  FIG. 1  has a shaft form extending in the direction of the axis line L, and notifies a user holding the linear actuator  1  of information by means of a vibration and the like. Therefore, the linear actuator  1  can be used as an operation section and the like of a game machine, in such a way as to make it possible to realize a new feeling by means of a vibration and the like. As shown in  FIG. 2 , the linear actuator  1  is provided with a stationary element  2 , including a cylindrical case  3  and the like, and a movable element  6 , being supported inside the case  3  so as to be movable in relation to the stationary element  2  in the direction of the axis line L; wherein the movable element  6  outputs information by means of a vibration in the direction of the axis line L. In the present embodiment, as explained below with reference to  FIG. 2  through  FIG. 6 ; the stationary element  2  is provided with the case  3 , a bobbin  4 , coils  5 , and the like; meanwhile the movable element  6  is provided with permanent magnets  7 , which makes up a magnetic drive mechanism  10  together with the coils  5 , a sleeve  8 , an external yoke  9 , and the like. The movable element  6  is supported by the stationary element  2 , by way of viscous elastic members  18  and  19 , and no spring component is used for supporting the movable element  6 . 
     (Configuration of the Case  3 ) 
       FIG. 3  is an exploded perspective view of the linear actuator  1  shown in  FIG. 1 , wherein the case is dismounted. As shown in  FIG. 1 ,  FIG. 2  and  FIG. 3 , the case  3  in the stationary element  2  includes a cylindrical torso part  35  stretching in the direction of the axis line L, a bottom plate part  36  provided at the other side L 2  in the direction of the axis line L of the torso part  35 , and an annular part  34  provided at the one side L 1  in the direction of the axis line L of the torso part  35 . From an inner side of the annular part  34 , a wiring substrate  25  becomes exposed; and the coils  5  are externally supplied with a drive signal by making use of a land  250  of the wiring substrate  25 . At a center of the bottom plate part  36 , there is shaped a sounding hole  360  to be described later. At an inner circumferential side of the torso part  35 , there exists a small diameter part  37 , where an almost middle position in the direction of the axis line L has a smaller inner diameter than both end sides in the direction of the axis line L have; and meanwhile, the both end sides in relation to the small diameter part in the direction of the axis line L become large diameter parts  38  &amp;  39  having a larger inner diameter than the small diameter part  37  has. 
     The case  3  has a form of being split in a circumferential direction, into a plurality of casing members (a first casing member  31  and a second casing member  32 ); and the case  3  is built up by combining the first casing member  31  and the second casing member  32 . The first casing member  31  and the second member  32  are provided with; side plate parts  315  and  325  for making up the torso part  35 , each side plate part having a semi-circular shape in its sectional view; first end plate parts  316  and  326  for making up the bottom plate part  36 , each first end plate part having an almost semi-circular shape; and second end plate parts  314  and  324  for making up the annular part  34 , each second end plate part having an arc-like shape, respectively. Inside the side plate parts  315  and  325 , there exist convex parts  317  and  327  for making up the small diameter part  37 , each convex part extending in a circumferential direction. 
     (Configuration of the Movable Element  6 ) 
       FIG. 4  is an exploded perspective view of the linear actuator  1  shown in  FIG. 1 , wherein components placed inside the case are disassembled.  FIG. 5  is an exploded perspective view of the linear actuator  1  shown in  FIG. 1 , wherein the external yoke is dismounted from an outside part of the coils; and  FIG. 5( a )  and  FIG. 5( b )  show conditions viewed from the one side L 1  in the direction of the axis line L, and conditions viewed from the other side L 2  in the direction of the axis line L, respectively.  FIG. 6  is an exploded perspective view of the linear actuator  1  shown in  FIG. 1 , wherein the permanent magnets and the like are dismounted from an inside part of the coils. As shown in  FIG. 2  and  FIG. 6 , the permanent magnets  7  are placed in plurality so as to be stacked in the direction of the axis line L, in the movable element  6 . For example, three or more permanent magnets  7  are stacked in the movable element  6 . In the present embodiment, five permanent magnets  7  are placed so as to be stacked in the direction of the axis line L. The permanent magnets  7  are columnar; and there is placed a spacer  71 , made of a magnetic plate being disk-like, between two permanent magnets  7  positioned next to each other in the direction of the axis line L. 
     In the permanent magnets  7  in plurality, as represented with ‘N’ and ‘S’ in  FIG. 6 ; with regard to the permanent magnets  7  positioned next to each other in the direction of an axis line, those permanent magnets  7  are placed in such a way that the same-polarity parts face each other. For example, in the direction of the axis line L, with respect to a first piece from the one side L 1  of the permanent magnets  7  and a second piece from the one side L 1  of the permanent magnets  7 , their N-polarity parts face each other by the intermediary of the spacer  71 ; in the meantime, with respect to a 21st piece of the permanent magnets  7  and a third piece of the permanent magnets  7 , their S-polarity parts face each other by the intermediary of the spacer  71 . 
     Accordingly, though there is generated a repulsion force between the permanent magnets  7  positioned next to each other, the permanent magnets  7  are so suppressed as to be aligned in the direction of the axis line L, by use of the sleeve  8 , the external yoke  9 , a first magnetic plate  91 , and a second magnetic plate  92  that are explained below with reference to  FIG. 2 ,  FIG. 3 ,  FIG. 4 ,  FIG. 5 ,  FIG. 6  and so forth. 
     As shown in  FIG. 2 ,  FIG. 5 , and  FIG. 6 , the movable element  6  includes the sleeve  8 , being non-magnetic and cylindrical, which surrounds a circumferential section of the permanent magnets  7 ; and the sleeve  8  is provided with a length in such a way that the sleeve  8  protrudes at the one side L 1  and the other side L 2  in the direction of the axis line L, out of pieces of the permanent magnets  7  that are positioned at both ends in the direction of the axis line L. Therefore, the pieces of the permanent magnets  7 , positioned at both the ends in the direction of the axis line L, are each indented inward, being in comparison to both ends of the sleeve  8  in the direction of the axis line L. The permanent magnets  7  and the sleeve  8  are fastened to each other by use of an adhesive (not shown); and in the meantime, the spacer  71  and the sleeve  8  are fastened to each other by use of an adhesive (not shown). At a time of rolling a sheet for the sleeve  8  so as to surround the permanent magnets  7  and the spacer  71  retained by use of a jig (not shown), the sleeve  8  is fastened to the permanent magnets  7  and the spacer  71  by use of the adhesive. Therefore, the permanent magnets  7  and the spacer  71  are supported by the sleeve  8  with a high-level linearity in the direction of the axis line L; and in the meantime, there are placed the coils  5  wound around the bobbin  4 , at an external side of the sleeve  8  in a radial direction, in such a way as to be distant from the sleeve  8 . 
     The movable element  6  includes; the first magnetic plate  91  provided at the one side L 1  in the direction of the axis line L of the sleeve  8 , the second magnetic plate  92  provided at the other side L 2  in the direction of the axis line L of the sleeve  8 , and the external yoke  9  provided with a cylindrical part  95  that surrounds the coils  5  at an external side in a radial direction. The cylindrical part  95  of the external yoke  9  is distant from the coils  5 . The first magnetic plate  91  is connected to an end part  951  of the one side L 1  in the direction of the axis line L of the cylindrical part  95  of the external yoke  9 , in a state where the first magnetic plate  91  contacts one piece of the permanent magnets  7 , which is provided at an end of the one side L 1  in the direction of the axis line L, among the plurality of the permanent magnets  7 . The second magnetic plate  92  is connected to an end part  952  of the other side L 2  in the direction of the axis line L of the cylindrical part  95  of the external yoke  9 , in a state where the second magnetic plate  92  contacts one piece of the permanent magnets  7 , which is provided at an end of the other side L 2  in the direction of the axis line L, among the plurality of the permanent magnets  7 . 
     In the present embodiment, the first magnetic plate  91  is provided with a first plate part  911  connected to the end part  951  of the cylindrical part  95 , and a first convex part  912  that protrudes from the first plate part  911  toward an internal side of the sleeve  8  in such a way as to contact the permanent magnet  7 . The second magnetic plate  92  is provided with a second plate part  921  connected to the end part  952  of the cylindrical part  95 , and a second convex part  922  that protrudes from the second plate part  921  toward an internal side of the sleeve  8  in such a way as to contact the permanent magnet  7 . Therefore, the permanent magnets  7  and the spacer  71  are retained by the first magnetic plate  91  and the second magnetic plate  92  from both the sides in the direction of the axis line L. In the present embodiment, the first magnetic plate  91  is connected to the cylindrical part  95  by way of welding, and the external yoke  9  is formed in such a way as to make the cylindrical part  95  and the second magnetic plate  92  as a single section. 
     On an external circumferential surface of the cylindrical part  95  of the external yoke  9 , there is a large diameter part  97  where a position, facing the small diameter part  37  of the case  3 , protrudes outward in a radial direction. The large diameter part  97  contacts the small diameter part  37  of the case  3  at a time when the movable element  6  moves in a direction that intersects with the axis line L. Therefore, both of the diameter part  97  shaped in the cylindrical part  95  of the external yoke  9  and the small diameter part  37  shaped in the torso part  35  of the case  3  make up a stopper  14  that regulates a movable range of the movable element  6  in a direction perpendicular to the axis line L, by means of the diameter part  97  and the small diameter part  37  contacting each other at a time when the movable element  6  moves in the direction perpendicular to the axis line L. 
     (Configuration of the Stationary Element  2 ) 
     As shown in  FIG. 2 ,  FIG. 3 ,  FIG. 4 ,  FIG. 5  and  FIG. 6 , the stationary element  2  includes; a first bobbin holder  41  placed at the one side L 1  in the direction of the axis line L in relation to the first magnetic plate  91 ; a second bobbin holder  42  placed at the other side L 2  in the direction of the axis line L in relation to the second magnetic plate  92 ; and the bobbin  4  being tubular, which stretches between the sleeve  8  and the external yoke  9 , in the direction of the axis line L. 
     The first bobbin holder  41  and the first magnetic plate  91  are distant from each other in the direction of the axis line L, and the second bobbin holder  42  and the second magnetic plate  92  are distant from each other in the direction of the axis line L, and then the bobbin  4  is distant from the sleeve  8  as well as the external yoke  9  in a radial direction. In the stationary element  2 ; on an external circumferential surface of the bobbin  4 , the coils  5  are wound around at a plurality of locations in the direction of the axis line L; and the coils  5  face gaps of the permanent magnets  7  by the intermediary of the bobbin  4  and the sleeve  8 , each gap being located between neighboring two of the permanent magnets  7  positioned next to each other in the direction of the axis line L. At an external circumferential side of the bobbin  4 , a flange part  48  is formed at an end part of the other side L 2  in the direction of the axis line L; and then between two coils  5  positioned next to each other in the direction of the axis line L, there is placed a spacer  55  being annular. 
     The first bobbin holder  41  includes a first end plate part  411  being circular, and a first side plate part  412 , being tubular, which is bent from an outer rim of the first end plate part  411  toward the other side L 2  in the direction of the axis line L; and the wiring substrate  25  is placed so as to be stacked on a surface at the one side L 1  of the first end plate part  411  in the direction of the axis line L. In the first end plate part  411 , there are shaped two slits  416 , being arc-like; and there are formed two through-holes  417  in the vicinity of each of the two slits  416 . Moreover, one of the two through-holes  417  overlaps with a through-hole  251  formed in the wiring substrate  25 . Therefore, an end part of a coil wire used as the coils  5  can be guided up to the land  250  of the wiring substrate  25 , by way of the through-holes  417  and  251 . 
     In the present embodiment, for connecting the bobbin  4  and the first bobbin holder  41 ; in the first magnetic plate  91 , there is formed a first through-hole part  910 , through which a first connecting part  46 , for connecting the bobbin  4  and the first bobbin holder  41 , passes. The first through-hole part  910  is a cutout part that is cut out so as to be fan-shaped in the first plate part  911 , around the first convex part  912  of the first magnetic plate  91 . The first connecting part  46  includes; a couple of first connecting plates  461  that protrude from the bobbin  4  toward the first bobbin holder  41 , and a couple of first supporting plates  419  that protrude from the first bobbin holder  41  toward the bobbin  4 ; and in the present embodiment, the first connecting plates  461  and the first supporting plates  419  overlap with each other, while individually having an arc-like sectional configuration. Furthermore, the couple of first connecting plates  461  individually fit into the two slits  416  shaped in the first end plate part  411  of the first bobbin holder  41 . Therefore, the first bobbin holder  41  and the first connecting plates  461  can be connected inside the slits  416  by way of welding and the like. 
     The second bobbin holder  42  includes a second end plate part  421  being circular, and a second side plate part  422 , being tubular, which is bent from an outer rim of the second end plate part  421  toward the one side L 1  in the direction of the axis line L; and at a center of the second end plate part  421 , there is shaped an opening part  420  that overlaps with the sounding hole  360  provided at the bottom plate part  36  of the case  3 . Incidentally, the bottom plate part  36  as well as the second end plate part  421  are provided in such a way as to become perpendicular to the direction of the axis line L. 
     In the present embodiment, for connecting the bobbin  4  and the second bobbin holder  42 ; in the second magnetic plate  92 , there is formed a second through-hole part  920 , through which a second connecting part  47 , for connecting the bobbin  4  and the second bobbin holder  42 , passes. The second through-hole part  920  is a cutout part that is cut out so as to be fan-shaped in the second plate part  921 , around the second convex part  922  of the second magnetic plate  92 . In the present embodiment, the second connecting part  47  includes; a couple of second connecting plates  471  that protrude from the bobbin  4  toward the second bobbin holder  42 , and a couple of second supporting plates  429  that protrude from the second bobbin holder  42  toward the bobbin  4 ; and in the present embodiment, the second connecting plates  471  and the second supporting plates  429 , individually having an arc-like sectional configuration, are connected by way of welding and the like, in a state of overlapping with each other. 
     In the present embodiment; on an external circumferential surface of the bobbin  4  and an external circumferential surface of the first supporting plates  419 , there are provided grooves  491 ,  492 , and  418  in order to guide an end part of a coil wire (not shown) that makes up the coils  5 , in the direction of the axis line L; and in the meantime, the grooves  491  and  492  extend up to an external circumferential surface of the first connecting plates  461 . Therefore, at a time of connecting the bobbin  4  and the first bobbin holder  41 , the grooves  491 ,  492 , and  418  are linked up. Accordingly, the end part of the coil wire can be guided up to the land  250  of the wiring substrate  25 , by way of the grooves  491 ,  492 , &amp;  418 , and the through-holes  417  and the through-hole  251 . 
     (Configuration of the Viscous Elastic Members  18  and  19 ) 
     In the present embodiment, the movable element  6  is supported by the viscous elastic members  18  and  19  in such a way as to be linearly movable in a reciprocating manner in the direction of the axis line L; the viscous elastic members  18  and  19  being provided at a plurality of positions being distant from each other in the direction of the axis line L, and provided in a section where the movable element  6  and the stationary element  2  face each other in a direction perpendicular to the direction of the axis line L. Meanwhile, the viscous elastic members  18  and  19 , being provided in plurality, are placed, between the external yoke  9  and the torso part  35 , being at both sides of the one side L 1  and the other side L 2  in the direction of the axis line L, in relation to the stopper  14 . 
     In the present embodiment, the viscous elastic members  18  provided at the one side L 1  in the direction of the axis line L, in relation to the stopper  14 , are individually fixed to each of an external circumferential surface of the cylindrical part  95  of the external yoke  9  and an internal circumferential surface of the torso part  35  of the case  3 ; at each of four locations equally spaced angularly in a circumferential direction. Furthermore, the viscous elastic members  19  provided at the other side L 2  in the direction of the axis line L, in relation to the stopper  14 , are also individually fixed to each of an external circumferential surface of the cylindrical part  95  of the external yoke  9  and an internal circumferential surface of the torso part  35  of the case  3 ; at each of four locations equally spaced angularly in a circumferential direction, in the same manner as the viscous elastic members  18  are. Incidentally, the viscous elastic members  18  and  19  are made of silicone gel having a needle entering level of 90 to 110. The ‘needle entering level’ is specified in JIS-K-2207 and JIS-K-2220; and the smaller the value is, it means that the harder the material is. In the meantime, ‘viscous elasticity’ represents a combined property including both of viscosity and elasticity, and the viscous elasticity is a property that is characteristically seen in a macro-molecule material, such as gel-like component, plastics, rubber and the like. Therefore, various kinds of gel-like components can be used as the viscous elastic members  18  and  19 . Moreover, as the viscous elastic members  18  and  19 , there can be used natural rubber, diene rubber (such as, styrene-butadiene rubber, isoprene rubber, and butadiene rubber), chloroprene rubber, acrylonitrile-butadiene rubber, and the like), non-diene rubber (for example, butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, urethane rubber, silicone rubber, fluorine rubber, and the like), various kinds of rubber materials such as thermoplastic elastomer and the like, as well as their modified materials. The viscous elastic members  18  and  19  are provided with a linear or non-linear extending property in relation to an extending direction. For example, the viscous elastic members  18  and  19  are provided with an extending property with which a non-linear element (spring coefficient) is greater than a linear element (spring coefficient), at a time of being compressed in a thickness direction (axial direction) so as to have a compressed deformation. In the meantime, the viscous elastic members  18  and  19  are provided with an extending property with which a linear element (spring coefficient) is greater than a non-linear element (spring coefficient), at a time of being pulled in the thickness direction (axial direction) so as to become extended. Therefore, at the time when the viscous elastic members  18  and  19  are compressed in the thickness direction (axial direction) between the movable element  3  and the supporting element  2  so as to have a compressed deformation, a great deformation of the viscous elastic members  18  and  19  can be controlled in such a way that a great change in a gap between the movable element  3  and the supporting element  2  can be controlled. On the other hand, in the case where the viscous elastic members  18  and  19  are deformed in a direction intersecting (shearing direction) with the thickness direction (axial direction), a deformation is made in a direction of extension by way of a pulling force, in either cases of a movement direction; so that, the viscous elastic members  18  and  19  have a deformation property with which a linear element (spring coefficient) is greater than a non-linear element (spring coefficient). Therefore, in the viscous elastic members  18  and  19 , a spring force in relation to a movement direction becomes constant. Accordingly, repeatability of an acceleration of vibration in relation to an input signal can be improved by use of a spring element in a shearing direction of the viscous elastic members  18  and  19 , so that a vibration having a delicate nuance can be materialized. Incidentally, immobilization of the viscous elastic members  18  and  19  to the external yoke  9  as well as immobilization of the viscous elastic members  18  and  19  to the case  3  are carried out by use of an adhesive, or a gluing agent, or by making use of an adhesive property of silicone-gel. 
     (Operation) 
     In the linear actuator  1  of the present embodiment; if the coils  5  are supplied with electric power from external (a higher-level device) by the intermediary of the wiring substrate  25 , the movable element  6  is moved in the direction of the axis line L in a reciprocating manner, by the magnetic drive mechanism  10  including the coils  5  and the permanent magnets  7 . Then, a user holding the linear actuator  1  with hand can obtain information by way of a vibration from the linear actuator  1 . At the time, with regard to a signal waveform to be applied to the coils  5 , a frequency is modified according to information to be transmitted. Furthermore, with regard to the signal waveform to be applied to the coils  5 , a polarity is reversed; and at the time, there is provided a difference in high and low speeds in a negative-polarity interval and a positive-polarity interval of a drive signal, in relation to a change of voltage. As a result, there is generated a difference between acceleration at a time when the movable element  6  moves toward the one side L 1  in the direction of the axis line L, and acceleration at a time when the movable element  6  moves toward the other side L 2  in the direction of the axis line L. Therefore, it is possible to make the user have illusion of the linear actuator  1  moving toward the one side L 1  or the other side L 2  in the direction of the axis line L. 
     Furthermore, in the linear actuator  1  of the present embodiment; a pressure change is discharged as an audible level sound from the sounding hole  360  of the case  3 , the pressure change being in accordance with a vibration of the movable element  6  in the direction of the axis line L. Therefore, it is possible to output information by use of a sound discharged from the sounding hole  360 . 
     Primary Advantageous Effect of the Present Embodiment 
     As explained above, in the linear actuator  1  of the present embodiment; at a time when the movable element  6  is vibrated in the direction of the axis line L by the magnetic drive mechanism  10 , a vibration is transferred to a user. Accordingly, information can be transferred by way of the vibration, while a form of the vibration is shifted in response to the information to be transferred. In the meantime, the case  3  includes the bottom plate part  36  provided with the sounding hole  360 , at the end part of the other side L 2  in the direction of the axis line L, so that a pressure change can be output as an audible level sound from the sounding hole  360 , the pressure change being in accordance with a vibration of the movable element  6  in the direction of the axis line L. Accordingly, the information can also be transferred by way of the sound. Therefore, a use of the linear actuator  1  can be expanded. 
     Moreover, according to the present embodiment; in the movable element  6 , the plurality of permanent magnets  7  are stacked in the direction of the axis line L; and in the meantime, the permanent magnets positioned next to each other in the direction of the axis line L are placed in such a way that the same-polarity parts face each other, so that density of magnetic flux, generated from a location between the permanent magnets  7  positioned next to each other, is high. Accordingly, even in the case of enhancing a thrust power, the number of permanent magnets  7  can be reduced so that an increase of a dimension of the movable element  6  in the direction of the axis line L can be controlled. Furthermore, the viscous elastic members  18  and  19  for suppressing resonance of the movable element  6  are provided at a plurality of locations being separate in the direction of the axis line L, so that the movable element  6  can appropriately be supported by the viscous elastic members  18  and  19 , without using any spring component, even though the dimension of the movable element  6  in the direction of the axis line L is great. Moreover, since there are stacked three or more permanent magnets  7  in the movable element  6 , a thrust power can be enhanced; and even in that case, the number of permanent magnets  7  can be still less. 
     Furthermore, since the sleeve  8  surrounds a circumferential section of the permanent magnets  7  in the movable element  6 , straightness of a stacked assembly of the plurality of permanent magnets  7  in a direction along the axis line L can be secured by the sleeve  8 , and a repulsion force acting between the permanent magnets  7  positioned next to each other in the direction of the axis line can be controlled by the first magnetic plate  91  and the second magnetic plate  92 . 
     Still further, since there are provided the grooves  491  and  492  on the external circumferential surface of the bobbin  4 , for guiding the end part of the coil wire that makes up the coils  5  in the direction of the axis line L, the end part of the coil wire can be guided up to a prescribed position by making use of the external circumferential surface of the bobbin  4 , even in the case where the coils  5  are provided in plurality in the direction of the axis line L. 
     Moreover, the stopper  14  for regulating the movable range of the movable element  6  in the direction perpendicular to the axis line L, is made up by use of the small diameter part  37  of the case  3  and the large diameter part  97  of the external yoke  9 , so that the external yoke  9  contacts the torso part  35  of the case  3  before the bobbin  4  contacts the sleeve  8  and the coils  5  contact the external yoke  9 . Therefore, damage on the bobbin  4  and the coils  5  can be suppressed. 
     Furthermore, the viscous elastic members  18  and  19  are placed, between the external yoke  9  and the torso part  35  of the case  3 , being at both sides of the one side L 1  and the other side L 2  in the direction of the axis line L, in relation to the stopper  14 ; and therefore the movable element  6  can appropriately be supported by the viscous elastic members  18  and  19 . Moreover, the viscous elastic members  18  and  19  are provided at locations in the stationary element  2  and the movable element  6 , the locations being face-to-face in a radial direction (i.e., a direction perpendicular to the axis line L); and therefore it is possible to suppress resonance at a time of vibrating the movable element  6  in the direction of the axis line L, by the viscous elastic members  18  and  19 . At the time, the viscous elastic members  18  and  19  deform in a shearing direction; and then, the viscous elastic members  18  and  19  have a deformation property with which a linear element is greater than a non-linear element. Therefore, repeatability of an acceleration of vibration in relation to an input signal can be improved, so that a vibration having a delicate nuance can be materialized. Accordingly, even though an interval changes between the stationary element  2  and the movable element  6  at a location where those two elements face to each other in the radial direction; it is possible to suppress resonance at a time when the movable element  6  vibrates in the direction of the axis line L, because a change in elastic modulus of the viscous elastic members  18  and  19  is less. 
     Still further, in the present embodiment, the case  3  is provided with a plurality of casing members (the first casing member  31  and the second casing member  32 ) arranged in a circumferential direction, and therefore it is easy to place the viscous elastic members  18  and  19  inside the case  3 . 
     Moreover, in the bottom plate part  36  of the case  3 , there is provided the sounding hole  360  that discharges a pressure change, in accordance with a vibration of the movable element  6  in the direction of the axis line L, as an audible level sound; and therefore the user can obtain information by way of vibration sensed with hand, and can furthermore obtain information by way of the sound discharged from the sounding hole  360 . 
     Other Embodiment 
     Though in the embodiment described above, the bottom plate part  36  having the sounding hole  360  is provided at the other side L 2  in the direction of the axis line L in the case  3 , a bottom plate part having a sounding hole may be provided at the one side L 1  in the direction of the axis line L. 
     DESCRIPTION OF REFERENCE NUMERALS 
       
     
       
         
           
               
               
               
             
               
                   
               
             
            
               
                 1: linear actuator 
                 2: stationary element 
                 3: case 
               
               
                 4: bobbin 
                 5: coils 
                 6: movable element 
               
               
                 7: permanent magnets 
                 8: sleeve 
                 9: external yoke 
               
            
           
           
               
               
            
               
                 10: magnetic drive mechanism 
                 14: stopper 
               
               
                 18 and 19: viscous elastic members 
                 25: wiring substrate 
               
            
           
           
               
               
            
               
                 31: first casing member 
                 32: second casing member 
               
            
           
           
               
               
               
            
               
                 34: annular part 
                 35: torso part 
                 36: bottom plate part 
               
            
           
           
               
               
            
               
                 37: small diameter part 
                 97: large diameter part 
               
               
                 41: first bobbin holder 
                 42: second bobbin holder 
               
               
                 46: first connecting part 
                 47: second connecting part 
               
               
                 91: first magnetic plate 
                 92: second magnetic plate 
               
               
                 95: cylindrical part 
                 317 and 327: convex parts 
               
               
                 360: sounding hole 
                 411: first end plate part 
               
               
                 412: first side plate part 
                 418, 491, and 492: grooves 
               
               
                 419: first supporting plates 
                 420: opening part 
               
               
                 421: second end plate part 
                 422: second side plate part 
               
               
                 429: second supporting plates 
                 461: first connecting plates 
               
               
                 471: second connecting plates 
                 910: first through-hole part 
               
               
                 911: first plate part 
                 912: first convex part 
               
               
                 920: second through-hole part 
                 912: second plate part 
               
               
                 922: second convex part