WO2006068322A1

WO2006068322A1 - Multi-axis linear motor, mounting head and component mounting machine using the multi-axis linear motor, magnetic force shield, and method of shielding magnetic force

Info

Publication number: WO2006068322A1
Application number: PCT/JP2005/024183
Authority: WO
Inventors: Kazunori Kanai; Hidehiro Saho; Noboru Yamasaki; Chikara Takata; Tatsuya Sano
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2004-12-24
Filing date: 2005-12-22
Publication date: 2006-06-29
Also published as: JP2006180645A; JP4731903B2

Abstract

To provide a multi-axis linear motor, a mounting head, and a component mounting machine having a plurality of linear motors which my not be affected by interaction of magnetic forces among each other. A magnetic force shield 60 is disposed between the adjacent linear motors 40 for preventing interaction of magnetic forces generated by respective linear motors 40. The magnetic force shield may also be disposed to a side where no adjacent linear motor exists. The magnetic force shield 60 may be formed by a magnetic body, or more specifically, by a steel plate. The magnetic force shield may be integrally formed with the linear motor 40 to form a unit type linear motor 401-403. The magnetic force shield 60 may be arranged in a rectangular pattern or circular pattern when viewed along axial direction of the linear motors 40.

Description

DESCRIPTION

MULTI-AXIS LINEAR MOTOR, MOUNTING HEAD AND COMPONENT MOUNTING MACHINE USING THE MULTI-AXIS LINEAR MOTOR, MAGNETIC FORCE SHIELD, AND METHOD OF SHIELDING MAGNETIC FORCE

Technical Field [ 0001 ] The present invention relates to a shaft type linear motor having a drive shaft movable linearly by applying driving currency . The present invention also relates to a multi-axis linear motor comprising a plurality of the shaft type linear motors , a component mounting machine for mounting components using the multi-axis linear motor, as well as a method of shielding magnetic force generated by the multi-axis linear motor which may cause magnetic interaction with other linear motors during controlling of such multi-axis linear motor .

Background Art [ 0002 ]

A shaft type linear motor is known in the art as one type of linear motors, comprising a stator in hollow and straight configuration, and a drive shaft driven linearly in the internal hole of the hollow stator ( e . g . , refer to JP 10-313566-A) . The stator is formed by a plurality of hol low cylindrical coils piled up coaxially, whose magnetic poles may be electrically controlled independently from each other . The drive shaft is comprised of a shaft magnetized in N poles and S poles alternately in axial direction . Such combination of coils and magnets may also be arranged in opposite manner between the stator and the drive shaft . By applying driving electricity to the coils of the stator to generate magnetic field that may interact with the permanent magnets on the drive shaft, repelling force among them is created which in turn forces the drive shaft to move in its axial direction relative to the stator . [ 0003 ] When a multi-axis actuator having a plurality of shaft type linear motors as described above is used for a precise machining apparatus, such as a component mounting machine, it is important that the actuator has good responding feature for enabling high speed movement, and has accurate positioning capability for locating the drive shaft at a desired position . Especially, when the multi-axis actuator is comprised of a plurality of linear motors , it is very important that precise controlling of an individual linear motor is to be assured so that the linear motor may perform predetermined operations correctly, and it should not be affected by other linear motors located nearby . [ 0004 ]

Several ways for detecting location of the drive shaft for improved control of a shaft type linear motor are known in prior art, such as using a l inear scale for optically detecting position of an obj ect ( e . g . , refer to JP 2000- 262034-A) , using linear resolver ( e . g . , refer to JP 2003- 32995-A) , or using a combination of a drive shaft having magnetized portion for detecting as well as for driving, and a stator having a magnetic sensor in addition to coils for driving the shaft (e . g . , refer to JP 7-107706-A) . [ 0005 ]

In general, combination of magnets and electromagnets

( coils ) has been used for controlling and driving a linear motor . Above mentioned JP 7-107706-A describes a- way using magnets for detection in addition to magnets for driving .

In order to move a drive shaft of a linear motor at a desired timing to a desired position, creating proper driving force (repelling force) between the stator and the drive shaft is required . For achieving this , it is required to create proper magnetic force in response to electricity applied to the coils of the stator, and to generate desired repelling force against opposing permanent magnets . Further, for achieving precise detection of the position of the drive shaft of the linear motor, it is required that a detecting sensor should correctly sense magnitude of magnetic field that is magnetized on an obj ect . Disclosure of Invention

[ 0006 ] . However, there is a problem in a multi-axis linear motor known in the art having a plurality of shaft type linear motors (hereinafter, referred to as "linear motor" ) , or a mounting head having such a multiple linear motors used for component mounting for precise controlling and operation . It is desirable to incorporate as much axes or nozzle assemblies as possible for sucking and mounting components into a single mounting head so as to improve efficiency of mounting operation . Further, since the mounting head is driven in high speed by XY robot or the like, the mounting head needs to be as light weighted as possible for reducing moment of inertia and for preventing vibration when it comes to stop . [ 0007 ] In order to meet such requirements , a plurality of linear motors need to be disposed as close as possible among each other . However, such tight arrangement of linear motors would make distance between adj acent liner motors shorter, which may in turn create problems in controlling linear motors and detecting position of the drive shafts properly due to interaction of magnetic forces generated from each of the linear motors . [ 0008 ]

It would be di fficult to generalize to what extent of close arrangement of linear motors would create such problems, since magnitude of interaction among the linear motors varies depending on various factors , such as specification of linear motors , or specification of permanent magnets and coils . It is known that such magnitude of interaction is related to maximum energy product (BHmax) , which is a maximum value of the product of residual magnetic flux density (Br) multiplied by magnetic preserving characteristic (HC) . In an extreme case, a linear motor would not move even by applying driving electricity because of magnetic effects caused by permanent magnets of adj acent linear motors . In a similar manner, a sensor for detecting movement of the drive shaft by sensing magnitude of magnetic force on the drive shaft may not detect accurate position of the drive shaft . [ 0009] Accordingly, it is required in prior art to arrange the linear motors by giving adequate distances among each other so as not to cause any interaction among the linear motors for controlling . Because of such an arrangement, a number of nozzles that can be accommodated in a single mounting head tends to be reduced, or size of a mounting head tends to be larger for accommodating required number of linear motors by giving enough distances among each other .

[ 0010 ] Accordingly, the obj ect of the present invention is to provide a multi-axis linear motor, in which individual linear motor may be disposed closely with each other, and yet such arrangement would not cause any problems due to interaction of magnetic forces created by each of the linear motors , and may achieve accurate controlling and accurate positioning of the drive shaft by means of magnetic sensor . It is also an obj ect of the present invention to provide a mounting head having such a multi- axis linear motor, and a component mounting machine comprising such a mounting head, as well as to provide a method of shielding magnetic force which may allow tight arrangement of a plurality of linear motors without being affected by magnetic interaction .

Summary of the invention [ 0011 ]

The above obj ects may be achieved by disposing a magnetic shielding means for preventing interaction among magnets and/or electromagnets of a plurality of linear motors located nearby . More specifically, the present invention includes the following . [ 0012 ]

One aspect of the present invention relates to a multi-axis linear motor having a plurality of shaft type linear motors each of which linear motors comprising : a stator having either permanent magnets or coils aligned linearly, and movable portion having either coils opposed to said permanent magnets of said stator, or permanent magnets opposed to said coils of said stator, capable to be driven relative to said stator by applying driving electricity to said coils , wherein said multi-axis linear motor further comprising a magnetic force shield for preventing magnetic interaction between the adj acent linear motors . [ 0013 ]

The linear motor desirably further includes a magnetic force shield on a side where no adj acent linear motor exists . The magnetic force shields may be disposed radially between the adj acent linear motors when said linear motors are arranged in a circular manner on a plane perpendicular to axial direction of the linear motors . [ 0014 ]

Another aspect of the present invention relates to a mounting head for picking up components supplied to component supply, and mounting the same onto predetermined mounting positions of a circuit substrate, comprising : a plurality of nozzles for sucking components ; vacuum supply for supplying vacuum to said nozzles ; and a multi-axis linear actuator for driving each of said plurality of nozzles in their axial direction, wherein said multi-axis linear actuator comprising any one of the multi axis linear motor described above . [ 0015] Yet another aspect of the present invention relates to a component mounting machine for picking up a component and mounting the same onto a circuit substrate, comprising : a component supply for supplying components continuously; a mounting head for picking up components from said component supply and mounting the same onto a circuit substrate ; a robot for transferring said mounting head; a substrate holding/transferring device for feeding a circuit substrate and holding the same ; and a controller for controlling over all operations of said component mounting machine, wherein said mounting head is comprised of the one described above . The component mounting machine may have two or more mounting heads operable independently from each other . [ 0016 ]

Yet another aspect of the present invention relates to a linear motor further comprising magnetic force shield for preventing outward expansion of magnetic field generated by the magnets and/or coils , which magnetic force shield is fixed at each of two sides of circumference of the stator opposing to each other, and extends in axial direction of the linear motor . The magnetic force shields fixed at two sides of the circumference of the stator may be aligned substantially parallel to each other when viewed along axial direction of the linear motor . The linear motor may include two pairs of magnetic' force shields each of which oppose to each other . In this case, said two pairs of magnetic force shields may be arranged in a rectangular pattern when viewed on a plane perpendicular to axial direction of the linear motor . The two pairs of magnetic force shields may also be formed in a manner surrounding circumference of the linear motor in axial direction thereof . In this case, configuration of said magnetic force shield surrounding the circumference of the linear motor may be in circular or rectangular configuration when viewed on a plane perpendicular to axial direction of the linear motor . The magnetic force shield may be formed by a magnetic body, or more specifically, by a steel plate . [ 0017 ]

Yet another aspect of the present invention relates to a magnetic force shield to be disposed between adj acently located linear motors with their axial direction aligned parallel to each other, or fixed outer circumference of a l inear motor for preventing interaction of magnetic forces generated from magnets and/or coils with other linear motors , wherein said magnetic force shield is formed by a sheet of a magnetic body . The magnetic force shield may be made by a steel plate . [ 0018 ]

Yet another aspect of the present invention relates to a method for shielding magnetic force for preventing interaction of the magnetic forces generated respective linear motors forming a multi-axis linear motor so as to achieve desired control of closely disposed linear motors independently from each other, wherein the method includes disposing a magnetic force shield made from a magnetic body between the adj acent linear motors . The magnetic body may be a steel plate .

Effect of the present invention [ 0019 ]

By implementing the present multi-axis liner motor having magnetic force shield, unfavorable effect for controlling and operating due to interaction of magnetic force generated from adj acent liner motors may effectively prevented, and desired operation of the l inear motors may by achieved . Through such desired operation, problems related to apparatus operation or producing components may be eliminated, and improved productivity and product quality may by obtained . [ 0020 ]

Further, more compact and light weighted multi-axis linear motor may be made by arranging individual linear motor in closer distance relations .

Brief Description of Drawings

[ 0021 ] Fig . 1 shows a schematic overall perspective view of a component mounting machine according to one embodiment of the present invention,

Fig . 2 shows a schematic perspective view of a XY robot used for the component mounting machine shown in Fig . 1 ,

Fig . 3 shows side view of X axis drive mechanism of the XY robot shown in Fig . 2 ,

Fig . 4 shows overall structural view of a mounting head used in the component mounting machine shown in Fig . 1 , Fig . 5 shows cross sectional view in Y direction of the mounting head shown in Fig . 4 ,

Fig . 6 shows a θ rotation mechanism for rotating nozzle assembly of the mounting head shown in Fig . 4 ,

Fig . 7 shows fragmentary enlarged view a linear motor included in the mounting head shown in Fig . 4 , Fig . 8 shows fragmentary enlarged perspective view of a first mounting head shown in Fig . 4 ,

Fig . 9A shows a front view of a mounting head according to one embodiment of the present invention, Fig . 9B shows a side sectional view of the mounting head shown in Fig . 9A,

Fig . 9C shows a plan view of the mounting head shown in Fig . 9A,

Fig . 9D shows a perspective view of magnetic force shield to be used for the mounting head shown in Fig . 9A,

Fig . 9E shows a side elevational view of shaft type linear motor to be used for the mounting head shown in Fig . 9A,

Fig . 9F shows a cross sectional view of the shaft type linear motor shown in Fig . 9E,

Figs . 1 OA, 1 OB and 1 OC show a layout of magnetic force shield according to another embodiment of the present invention, and

Figs . HA, HB and HC show a perspective view of a unit type linear motor according to yet another embodiment of the present invention .

Best Mode for Carrying Out the Invention

[ 0022 ] The embodiments of a multi-axis linear motor having a magnetic force shielding means according to the present invention, and an apparatus using such a multi-axis linear motor will now be described by referring to the appended drawings . In the following description, a component mounting machine is being discussed as an example, but it should be understood that the present is not limited thereto . Fig . 1 shows an overall schematic perspective view of a component mounting machine 101 according to the present embodiment . The component mounting machine 101 comprises : a loader 1 for feeding a circuit substrate 2 into the component mounting machine 101 ; an unloader 11 for unloading the circuit substrate 2 onto which components have been mounted by the component mounting machine 101 , and a first substrate holding/transferring device 3 having a pair of support rails for transferring and holding the circuit substrate 2 fed by the loader 1. [ 0023 ]

During operational stage of the component mounting machine 101 shown in Fig . 1 , the circuit substrate 2-0 on the loader 1 is being transferred into the component mounting machine 101 , components are being mounted onto the circuit substrate 2-1 held by the first substrate holding/transferring device 3 , and the circuit substrate 2- 3 with component mounted thereon i s being unloaded from the component mounting machine 101 by the unloader 11 , all of which operations are being performed simultaneously . In this specification, a circuit substrate in general will be referred to as "circuit substrate 2 " , while a circuit substrate located in a specific position will be referred to as either "circuit substrate 2-0" , " circuit substrate 2-1 " , " circuit substrate 2-2 " , or " circuit substrate 2-3 " . In a similar manner, an element in general will be referred to by its reference numeral only, while a specific element will be referred to by its reference numeral together with suffix, such as "a" , "b, "c" etc .. [ 0024 ]

The component mounting machine 101 further includes component supplies 8A and 8B at a position in a front side in Y axis direction of component mounting operation area in the drawing for holding component supply cassettes 80 for continuously supplying components to component pick up position . The component mounting machine 101 may also include a tray type component supply 8C for holding components on a tray located near the component supply 8B, which components are also to be mounted onto the circuit substrate 2. The components being supplied by the cassettes 80 at the component supply 8A and 8B are mainly smaller size chip type components , while the components being supplied by tray type component supply 8C are mainly IC components , such as ID chips or components with non- standard configuration such as connectors . [ 0025]

The component mounting machine 101 further includes : a base portion 16 where the component supply 8A and 8B are located; a first mounting head 4 for sucking components from the component supply 8A, 8B or 8C and mounting them onto the circuit substrate 2 ; a recognition camera 9 for imaging a condition of a component being sucked and held by the nozzles 39, which are attached to the end of the nozzle assemblies 10 attached to the first mounting head 4 , and controller 100 for controlling overall operations . [ 0026]

The first mounting head 4 is structured to move along two axes in horizontal direction on the upper surface of the base portion 16 of component mounting apparatus 101 , or mounting operation area, by means of a XY robot 5. A plurality of nozzles 39, such as twelve nozzles, are detachably attached to the first mounting head 4 for sucking and releasing the components . For example, the first mounting head 4 may move to the position where the components supplied at the component supply 8A, 8B and 8C are to be picked up, or to the position opposing to the circuit substrate 2-1 being held by the first substrate holding/transferring device 3 for mounting components thereon, or to the position opposing to the nozzle station 7 for changing the nozzle 39 attached to the mounting head 4 , upon necessity . The nozzle station 7 is located near the component supply 8A in the mounting operation area and holding a variety types of nozzles to be used for mounting different kinds of components . [ 0027 ]

The component mounting machine 101 shown in Fig . 1 further includes a second substrate holding/transferring device 13 , a second mounting head 14 , a XY robot 15, a nozzle station 17 , component supplies 18A-18C, and a recognition camera 19, all of which are similar to those explained above, but operate at distal side in Y direction on the component operation area for further mounting components onto a circuit substrate transferred by the first substrate holding/transferring device 3. Furthermore, load cells 12 are provided on the mounting operation area for measuring and adjusting height of nozzles 39 attached to both of the first and the second mounting head 4 and 14 , by abutting the nozzles 39 onto the load cells 12. [ 0028 ]

In such a structure, the component mounting machine 101 shown in Fig . 1 includes two component mounting areas disposed on the base portion 16 , which may perform component mounting operations onto respective circuit substrates 2 by using the first mounting head 4 and the second mounting head 14 simultaneously and independently . [ 0029 ]

Fig . 2 shows a perspective view of the XY robots 5 and 15 used in the component mounting machine 101 shown in Fig . 1. Referring to Fig . 2 , the XY robots 5 and 15 include a first X axis portion 6b for movably supporting the first mounting head 4 (not shown in the drawing) and for driving the same in X axis direction, a second X axis portion 6c for movably supporting the second mounting head 14 and for driving the same in X axis direction, and a pair of Y axis portions 6a disposed at both ends in X axis direction of the base portion 16 ( see Fig . 1 ) for supporting both of the X axis portions 6b and 6c at their both ends, and for driving the same in Y axis direction . [ 0030 ]

The Y axis portions 6a are capable of driving two X axis portions 6b and 6c independently from each other . Namely, the first mounting head 4 may be driven both in X axis direction and Y axis direction in the foreside of the base portion 16 in the drawing by means of the first X axis portion 6b and both of the Y axis portions 6a, while the second mounting head 14 may be driven both in X axis direction and Y axis direction in the back side of the base portion 16 in the drawing by the second X axis portion 6c and both of the Y axis portions 6a . Such movement of the first and the second X axis portions βb and βc may be controlled independently from each other . Further, movement in Y direction of both of the X axis portions 6b and 6c are mutually controlled so as not to collide with each other . The first mounting head 4 and the second mounting head 14 are structured to move in X and Y directions by means of a linear motor, ball screw or the like included in the XY robots 5 and 15. [ 0031 ] The component mounting machine 101 further includes a controller 100 for controlling over all component mounting operations including loading and unloading of a circuit substrate 2 , component pick up, component recognition, and component mounting, which operations are related to each other . The controller 100 is connected to each of the component supplies 8A, 8B, 18A and 18B, component supply cassettes 80 , the first and second mounting heads 4 and 14 , the recognition cameras 9 and 19, the first and second substrate holding/transferring devices 3 and 13 , the XY robots 5 and 15, the loader 1 , and the unloader 11. The controller 100 also includes a data base and a memory, which may include a library of component related information such as configuration or height of a variety of components to be mounted, a library of substrate related information such as configuration of the substrate, a library of nozzle related information such as configuration and stocked position of a variety of nozzles , NC data for controlling mounting operation such as layout program or layout information of mounting positions on the substrate for respective components to be mounted thereon, and information of holding position of the substrates held by both of the substrate holding/transferring devices 3 and 13, and the like . All these information or data are stocked in replaceable manner . [ 0032 ]

Fig . 3 shows a sectional view of the X axis portion 6b or 6c . As shown in the drawing, the X axis portion 6b or 6c includes a X axis linear motor shaft 32 and a pair of X axis linear guides 33 at upper and lower sides relative to the linear motor 32, both of which are provided to the X axis flame 36 in Y shaped configuration in its cross section . The X axis linear motor shaft 32 engages with a X axis driving portion 34 of a mounting head driving portion 31. The mounting head driving portion 31 is structured to move in X axis direction guided by a pair of X axis linear guides 33. The X axis flame 36 is provided with a X axis linear scale 38 , which is used for detecting position of the mounting head driving portion 31 by means of a position sensor 37 attached to the mounting head driving portion 31. The mounting head driving portion 31 has an attaching plane 35 for attaching either the first mounting head 4 or the second mounting head 14. When an ordinary motor is used instead of the linear motor for driving in X axis direction, ball screw rather than linear motor shaft 32 is generally used .

[ 0033 ]

Detailed structure of the mounting heads 4 and 14 is now explained by referring to appended drawings . In the following description, the first mounting head 4 is being discussed as a representative, since both first and second mounting heads 4 and 14 are basically structured in a similar manner . Fig . 4 shows overall view of the mounting head 4 , and Figs . 5-8 show partial detailed view of the mounting head 4. [ 0034 ]

Referring to Fig . 4 , the mounting head 4 includes a plurality of nozzle assemblies for sucking, such as twelve nozzle assemblies l Oa-101 as shown in the drawing . Each of the nozzle assemblies 10 are disposed in six rows in X axis direction having a distance pitch Px among each other, and in two rows in Y direction having a distant pitch Py between each other . The mounting head 4 is structured by a multi-axis linear motor . In this specification in which the nozzle assemblies 10 are disposed as above, each of the nozzle assemblies 10 in front row in Y axis direction in the drawing from left to right in X axis direction would be called first to sixth nozzle assembly l Oa-l Of, respectively, and each of those in back row in Y axis direction in the drawing from left to right in X axis direction would be called seventh to twel fth nozzle assembly l Og-101 , respectively ( in the drawing only nozzle assembly of 10a, 10b and 1 Of are shown) . [ 0035]

At the component supply 8A (or 8B, refer to Fig . 1 ) , a plurality of component supply cassettes 80 are held along X axis direction by having distance pitch of L among each other . Desirably, the above distant pitch Px in the nozzle assembly 10 arrangement is set to be equal to several times of such distance pitch L of the component supply cassettes 80 arrangement ( Px = L X n ) . In the present embodiment , the distance pitch Px of nozzle assemblies 10 equals to the distance pitch L of component supply cassettes 80 (i . e . , n=l , Px = L) . Each of the nozzle assemblies l Oa-101 has a similar structure . [ 0036 ]

Fig . 5 shows assembled condition of the mounting head 4 shown in Fig . 4 attached to the X axis portion 6b or 6c shown in Fig . 3. Referring to Fig .5, each of the nozzle assemblies 10 (only the first and seventh nozzle assemblies 10a and 1 Og located in front most row may be seen in Fig . 5, and rest of the nozzle assemblies 10 are located behind either one of these nozzle assemblies 10a and 1 Og) is supported by a housing 46 located upper part of the mounting head 4 and outer shell 53 having a ball spline nut 53a so as to be movable along Z axis direction, and rotatable around an axis parallel to Z axis . The nozzle assembly 10 is , as described later, structured to move along Z axis by means of an actuator ( linear motor) 40. Further, the nozzle assembly 10 includes a spline shaft 44 , nozzle 39 attached to the lower end of the spline shaft 44 , a drive shaft 45 aligned coaxially with the spline shaft 44 , and a timing pulley 41 for rotating the nozzle assembly 10 , which is called θ rotation . [ 0037 ] The drive shaft 45 acts as a driving shaft for the actuator 40 to drive the nozzle assembly 10 upward and downward in Z axis direction . A timing pulley 41 is provided for connecting the spline shaft 44 , which may relatively move along Z axis direction, but their relative rotation around Z axis is blocked . Fig . 6 shows such details, which is a plan view illustrating relations between the nozzle assembly 10 and the timing pulley 41 , as well as timing belt 43. A timing belt 43 engages each of the timing pulleys 41 of the first to sixth nozzle assemblies 1 Oa-I Of . The timing belt 43 also engages five tension pulleys 43a and 43b so as to achieve proper engagement between the pulleys 41 and the six nozzle assemblies 1 Oa-I Of . By means of such engagement of the timing belt 43 , forward and backward rotation of a drive motor 42a for θ rotation is transferred to the first to sixth nozzle assemblies l Oa-l Of via timing belt 43 , which in turn rotates all of them simultaneously to perform θ rotation ( rotation of nozzle assembly 10 around its longitudinal direction) . [ 0038 ]

In a similar manner, another timing belt 43 engages the timing pulleys 41 of the seventh to twel fth nozzle assemblies l Og-101 , and by such an arrangement, forward and backward rotation of a drive motor 42b may cause θ rotation of the seventh to twelfth nozzle assemblies 1 Og- 101 via the timing belt 43, and rotate all of them simultaneously . Driving mechanism by using such a pair of timing belts 43 is merely an example .

[ 0039] Back to Fig . 5, the actuator 40 is structured by a shaft type linear motors (hereinafter, the reference numeral " 40" is given to a " linear motor" as well ) , and by means of the linear motor 40 , the nozzle 39 associated with that particular linear motor 40 is selectively moved upward or downward for picking up component or for mount the same . Each of the component supply cassettes 80 hold components ready for pick up operation at a component pick up position . The component pick up positions are arranged along X axis direction shown in the drawing by having a constant distance pitch L among each other as described above . By this way, each of the nozzles 39 aligned in X axis direction may be positioned opposed to each of the component supply cassettes 80 , respectively . For example, the first nozzle assembly 10a may be positioned opposing the component pick up position of the first component supply cassette 80, and simultaneously the second nozzle assembly 10b may be positioned opposing the component pick up position of the second component supply cassette 80 etc . , so that the nozzle assemblies 10 may pick up components from a series of component supply cassettes at the same time .

[ 0040 ]

Now the linear motor 40 used for the mounting head 4 and 14 is described by referring to appended drawings . In Fig . 5, the linear motor 40 includes a drive shaft 45 coaxially arranged with the spline shaft 44 of the nozzle assembly 10 , and a stator 47 arranged inside the housing 46 of the mounting head 4 having coils 48 and a magnetic sensor 49 for position detection . In the example shown in Fig . 5, the magnet sensor 49 for position detection is connected to the stator 47 , but the sensor 49 may be provided outside of the stator 47, which will be described later .

[ 0041 ] The drive shafts 45 connected to the first to sixth nozzle assemblies l Oa-l Of (nozzle assemblies in right hand row shown in Fig . 5 ) have a hollow structure 45e, which may effect vacuum to the nozzle 39 attached to the lower end of the drive shaft 45 through the hollow structure 45e by sucking air at the sucking connector 45b located upper end of the drive shaft 45. Contrary to this , the drive shafts 45 connected to the seventh to twelfth nozzle assemblies lOg-101 (nozzle assemblies in left hand row in Fig . 5) have a rigid structure, and the spline shaft 44 has sucking opening 45c for sucking air . The sucking opening 45c is connected to a connection nozzle 45d formed on the outer shell 53, so as to effect vacuum pressure to the nozzle 39 attached to the lower end of the spline shaft 44 by sucking air in the spline shaft 44. [ 0042 ]

Each nozzle assembly 10 is structured to move up and down by means of the linear motor 40, but it is also supported upwardly by a spring 52 to prevent the nozzle assembly 10 from descending due to gravity . That is, in between a spring seat 54 formed to the outer shell 53 housing a ball spline nut 53a therein for supporting the spline shaft 44 of the nozzle assembly 10 , and another spring seat 55 fixed to the drive shaft 45 which is integrally formed to the spline shaft 44 , the spring 52 having longer free length than the distance between the two spring seats 54 and 55 is provided coaxially with the drive shaft 45. By such arrangement, the drive shaft 45 is biased upwardly in the drawing, hence the nozzle assembly 10 does not move downwardly due to gravity . The spring seat 55 also acts as a stopper for preventing the drive shaft 45 at the original position from further moving upward by abutting between the lower end of the stator 47 and the spring seat 55. [ 0043 ] Now a structure of the linear motor 40 is explained by referring to Fig . 7. The drive shaft 45 is formed by a plurality of cylindrically configured permanent magnets 45a having the same length, and magnetized in such a manner that S pole and N pole are formed at each end of the permanent magnet 45a in axial direction, but oriented in different ways between the adj acent magnets 45a so that either N poles or S poles of the two magnets 45a face each other . Magnetic poles of the drive shaft 45 may be formed by piling up a plurality of cylindrically shaped magnets having the same length as described above, or by covering the outer circumference of the drive shaft with permanent magnets in a sheet form surrounding the shaft . The drive shaft may also be formed by magnetizing the shaft itself .

[ 0044 ] The stator 47 is formed by a plurality of coils 48 in a ring shape having a cylindrical hole in its center, through which the drive shaft 45 may be inserted . The coi ls 48 are piled up coaxially in Z axis direction, and the drive shaft 45 is inserted into the hole formed by each of the coils 48. The coils 48 are arranged so that when the drive shaft 45 is inserted, the coils 48 may oppose to the corresponding permanent magnets 45a of the drive shaft 45. Specifically, the coils 48 are fixed in the stator 47 and disposed so as to surround the circumferences of the permanent magnets 45a, and to oppose to the magnets 45a, respectively for driving the drive shaft 45. The coil 48 is formed by winding a wire around the core in a loop shape . It is desirable that the coils 48 are formed along the circumference curvature of the permanent magnets 45a so as to minimize loss of magnetic field . [ 0045]

Bearings 50a and 50b ( refer to Fig . 5) are provided at both end of the piled up coils 48 to guide the drive shaft 45 so as not to dislocate the position relative to the axial center of the coils , and to hold the drive shaft 45 in movable condition along the its axial direction . A pair of position detecting sensor units 49a and 49b are disposed at the position lower than the bearing 50b . Each of the position detecting sensor units 49 is formed by a pair of magnetic sensors (either 491 and 492 , or 493 and 494 ) arranged along the axial direction of the drive shaft 45 having a distance equivalent to 1/2 of the length of one permanent magnet 45a . By this arrangement, when either one of the magnet - sensors detects maximum magnitude of the magnetic force ( i . e . , when one of the magnet sensors is located at the position opposing one end of the permanent magnet 45a ) , the other magnetic detecting sensor may detect substantially 0 magnitude of magnetic force ( i . e . , the another magnet sensor is located at the position opposing center of one permanent magnet 45a in axial direction) . Movement of the drive shaft 45 may be detected by sensing magnitude of the magnetic force output from a pair of the magnetic detecting sensor units 49 as arranged above . [ 0046 ] The above described sensor unit 49 for position detection by detecting magnetic force of driving magnetic polar of the drive shaft is merely an example, and other position detecting means may possibly be used . [ 0047 ] Referring to Fig . 8 , the housing 46 of the mounting head 4 is formed in rectangular parallelepiped configuration having a thickness enough to exert required mechanical strength, and made by non-magnetic body such as plastic, aluminum or ceramic . The housing 46 has through holes 56 on upper surface of the housing 46 having larger diameter than that of the drive shaft 45 for movably receiving the drive shaft 45. The position of the through holes 56 are coaxially aligned with the hollow cylinder formed by the coils 48 of the stator 47 disposed inside the housing 46. Female threads 57 are formed on a side of the housing 46 for fastening the housing 46 onto the attaching plane 35 of the mounting head driving portion 31 ( refer to Fig . 3 ) .

[ 0048 ] Operations of the component mounting machine 101 as structured above are as follows . First, components are supplied to component supply 8A-8C, and a mounting head 4 driven by XY robot 5 moves to a position opposing the component supply 8A-8C . Nozzle 39 is lowered from the mounting head 4 for contacting a component, and then the nozzle 39 picks up the component from the component supply cassette 80 by sucking effect of vacuum. The mounting head 4 is then moved to the position opposing the recognition camera 9 by means of XY robot 5, and holding condition of the component is imaged . The holding condition of the component is evaluated based on the image, and i f the mounting controller 100 judges that the component is held in proper condition, then the mounting head 4 is further moved to the position opposing the substrate 2. During such movement , θ rotation is given to the component based on the evaluation result, and angular position of the component is corrected . After the mounting head 4 arrives at the predetermined position opposing a mounting position of the substrate 2 , the mounting head 4 descend the nozzle 39, and mount the component onto the mounting position . All the nozzles 39 operate in a similar manner, and repeat the same continuously . [ 0049 ] According to the present embodiment, the mounting head 4 as described above is provided with magnetic force shields 60 as shown in Fig . 5 for preventing interaction of the magnetic forces between adj acent linear motors 40. More detail is described by referring to Figs . 9A-9D . Fig . 9A shows a front view of the housing 46 having the mounting head 4a including such magnetic force shields 60. Through opening on the front side of the housing 46, linear motors 40 for six nozzle assemblies 10 located in front row can be seen in the drawing ( six other linear motors 40 in the second row are located behind each of the linear motors 40 of the front row) . The mounting head 4a according to the present embodiment has total seven magnetic force shields 60, located between the adj acent linear motors 40, as well as outside of the two linear motors 40 located at both ends in the front row . In other word, all the linear motors 40 shown in the drawing are provided with magnetic force shields 60 at both right hand side and left hand side in the drawing . Each magnetic force shield 60 passes through inside of the housing 46 in vertical direction, and extends in a direction perpendicular to the drawing . Each magnetic force shield 60 has fixing portion 61 formed by bending a portion of its body in "L" shape, at which the magnetic force shield 60 is fixed to the upper surface of the housing 46. Lower end of the magnetic force shield 60 extends to the level equivalent to the lowest position of the stroke of the drive shaft 45 ( not shown in the drawing) of the linear motor 40. [ 0050 ]

For the purpose of only protecting interaction of the magnetic force between the 6 adj acent linear motors 40 in front row, five magnetic force shields 60 located between the adj acent liner motors 40 would be enough . However, in such an arrangement of the magnetic force shields 60, magnetic fields generated by the electromagnets of the linear motors located both ends of a row is not stable, hence controlling of these two linear motors becomes difficult . Accordingly, it is desirable to add magnetic force shields 60 at outside of both ends of a row of the linear motors 40 as well , regardless of interaction of magnetic force . [ 0051 ]

In the mounting head 4a shown in Fig . 9A, position detecting sensor units 49 for detecting position of the drive shaft 45 are located at the upper extended portion of the drive shafts 45, instead of inside of the stators 47 of the linear motors 40 as described before . A fan 65 shown in left hand side of the drawing is a cooling fan for forcedly introducing cooling air into the array of linear motors 40, which will be described later . [ 0052 ] Fig. 9B shows a cross sectional side view of the mounting head 4a shown in Fig . 9A. Referring to the drawing, the mounting head 4a is fixed to the attaching plane 35 of the mounting head driving portion 31 , and two linear motors 40 of nozzle assemblies 10a and 1 Og located very front of the first row and the second row are shown

(other nozzle assemblies 10 are located behind either one of these two nozzle assemblies 10a and 1Og) . On both right and left sides of the linear motors 40, there provided a plurality of fins 40a to be used for cooling heat generated from the linear motors 40. Especially in the central portion of the two liner motors 40 where more heat is to be generated, air is forcedly introduced to pass through the housing 46 in a direction perpendicular to the drawing by means of a cooling fan 65 ( refer to Fig . 9A) for achieving higher cooling efficiency . [ 0053 ]

In Fig . 9B, the magnetic force shield 60 is shown in its span direction (partially shown by broken lines ) , rather than its thickness direction as shown in Fig . 9A. The magnetic force shield 60 according to the present embodiment is formed integrally by a single plate which may cover the two nozzle assemblies 10 in both first and second rows together, and this will be described later . [ 0054 ] A position detecting sensor unit 49 is provided at the upper section of the drawing, which include detecting portion 59 extending from the drive shaft 45 of the linear motor 40 via a flexible j oint 58. Although the sensor unit 49 is a type to detect N poles and S poles alternately magnetized along axial direction of the detecting portion 59 by using a magnetic detecting sensor 491 , other type of detection may also be used, such as optical detection by using a linear scale . The flexible joint 58 is useful for avoiding accurate alignment of axes between the drive shaft 45 of the linear motor and the detecting portion 59. [ 0055 ]

In the aspect as shown in Fig . 5, the magnetic detecting sensor 491 detects magnetic force generated from the magnets 45a of the drive shaft 45. Since such magnets 45a are designed for driving the drive shaft 45, their magnetic forces are normally too strong to be used for position detection . Therefore, it may be required to shield such strong magnetic force generated by the adj acent linear motors 40 by using the magnetic force shield 60 for accurate detection . Contrary to this, according to the example shown in Fig . 9B, as the position detecting sensor 49 may detect relatively weak magnetic force designed to be used exclusively for detection, interaction between adj acent linear motors 40 are - limited, hence the sensor unit 49 may be positioned outside of coverage by the magnetic force shield 60. Of course, it is possible to extend the magnetic force shield 60 to cover the sensor unit 49 as well , i f necessary . [ 0056 ] Fig . 9C shows a plan view of the mounting head 4a according to the present embodiment . As is clear from the drawing, total seven magnetic force shields 60 are fixed on the top of the housing 46 at the fixing portions 61 ( fastening devices such as screws for fixing the shield are not shown in the drawing) , and extend along Y axis direction for covering nozzle assemblies 10 of both first and second rows . In the example shown in the drawing, distance pitch Py between adj acent nozzle assemblies 10 in the first and the second rows along Y axis direction is set to be wider than distance pitch Px along X axis direction ( Py>Px) . In such arrangement, controlling of each of the shaft type linear motors 40 may not be affected by interaction of magnets without providing magnetic force shields 60 between the adj acent nozzle assemblies 10 in Y axis direction . However, it is also possible to provide similar magnetic force shields 60 in Y direction as well , if necessary . The cooling fan 65 for introducing air for cooling to the area between two rows of the linear motors 40 as described above is shown in lower end of the housing . [ 0057 ]

Fig . 9D shows a specific example of the magnetic force shield 60 usable for the present embodiment . In the drawing, the magnetic force shield 60 is desirably formed by a material of magnetic body, such as steel plate, but other materials may also be used as far as such materials may perform magnet shielding function . In an example shown in the drawing, the magnetic force shield 60 may be formed easily by stamping operation, such as by shearing, piercing and bending a steel plate . The fixing portion 61 is formed by partially bending upper portion in a shape of "L" , and the magnetic force shield 60 may be fixed on top of the housing 46 of the mounting head 4a by screws 64 passing through fixing holes 63 formed at the fixing portion 61.

[ 0058 ] A long hole 62 in the central area of the magnetic force shield 60 is designed to introduce air to pass in X axis direction of the mounting head 4a so as to cool down heat generated by the liner motors in two rows . Such a hole 62 is not necessary if the mounting head 4 has a single row of linear motors only . [ 0059 ]

By providing the magnetic force shield 60 as described above, interaction of magnetic forces generated by adj acent liner motors 40 is prevented, and each of the magnetic force of corresponding liner motor is formed in an independent close loop magnetic field . Accordingly, each of the linear motors 40 is not affected by magnetic force of other liner motors 40 , and undesirable influence on controlling and operating the linear motors may successfully be prevented .

[ 0060 ]

According to experiments conducted by the present inventers, remarkable results could be achieved by the present embodiment, namely by simply inserting one sheet of steel plate between the adj acent liner motors 40 , the linear motors 40 turned into controllable and operable condition, which linear motors 40 did not move at all even applying driving electricity to coils 48 when such a steel plate did not exist . Specification of such a steel plate may vary depending upon other factors such as magnitude of the magnetic force . However, favorable results could be achieved even by using, for example, a steel plate having thickness as thin as several tenths of millimeters ( 1/10 mm) . The steel plate referred to in this specification should include iron plate . [ 0061 ]

Figs . 9E and 9F show a specific example of the shaft type linear motor 40 that may be used for the mounting head 4 of the present embodiment . Referring to Figs . 9E and 9F, the linear motor 40 has many fins 40a surrounding the circumference for effectively cooling heat generated by the linear motor 40. Cable 40b extend from the main body of the linear motor 40 , which is connected to the stator for controlling movement of the drive shaft 45. Referring to Fig . 9F showing cross sectional view of the linear motor 40 , the drive shaft 45 is formed by a series of permanent magnets 45a, which are opposing to a series of coils 48 , respectively, forming the stator 47. Fig . 9E shows lower most position of the drive shaft 45, while Fig . 9F shows upper most position thereof . [ 0062 ]

Figs . 1 OA-I OD show exemplary layout arrangement of magnetic force shields 60 corresponding to a variety of layouts of a plurality of linear motors 40 viewing along axial direction of the linear motors 40. In Fig . 1 OA, linear motors' 40 are arranged in circular manner on a plane perpendicular to their axial direction, and the magnetic force shields 60 are disposed between adj acent linear motors 60 in radial pattern . In this arrangement, one linear motor 40 has two magnetic force shields 60 at both sides thereof, and both of the two magnetic force shields 60 are not parallel but arranged having a certain angle between them. Such angular arrangement may be allowed for functioning shielding effect up to a certain degree of the angle, but to what extent such angle is allowed may depend upon other factors , such as ^' specification of the linear motors 40, or distance between the adj acent linear motors 40, etc .. In the example shown in Fig . 10a, the linear motors 40 are arranged in a circular manner, but some other arrangements , such as elliptical manner, may also be possible . In general , the magnetic force shields 60 may be disposed between the adj acent linear motors 40 and may prevent interaction of these magnetic forces when a plurality of linear motors 40 are arranged in a loop having a certain distance between the adj acent motors 40 with their longitudinal axes oriented substantially parallel . [ 0063 ]

Fig . 1 OB shows a case where a plurality of linear motors 40 are laid out in a checkered manner . In this arrangement, the magnetic force shields 60 may be disposed between the adj acent linear motors 40 in a grid like pattern . When distance pitches between the adj acent linear motors 40 in horizontal direction and vertical direction are the same as shown in the drawing, layout of the magnetic force shields 60 would be in square pattern . Those linear motors 40 located outer side of a group of motors usually do not have adj acent linear motors 40 at least in one direction . Even in such a case, it is desi'rable to dispose the magnetic force shield 60 in that direction of each of such linear motors 40 as well for the purpose of correctly controlling operation of that particular linear motor 40. [ 0064 ] Fig . 1 OC shows a case where a plurality of linear motors 40 are arranged in a polka-dotted manner . In this arrangement, interaction of magnetic forces may be prevented by surrounding outer circumference of each of the linear motors 40 by a tubular magnetic force shield 60. This arrangement of surrounding the linear motor 40 by the magnetic force shield 60 may also be applicable to the case as shown in Fig . 1 OA where angle of radial pattern becomes too big for a plate type magnetic force shield 60 to be effective .

[ 0065 ] Figs . 11A-11C each shows a unit type linear motor which is designed to prevent magnetic interaction of its own, in which the magnetic force shield 60 is formed as an integral part of the linear motor 40. [ 0066 ] Fig . HA shows a unit type linear motor 401 having a pair of magnetic force shields 60 facing each other and attached to the outer circumference of the linear motor 40. The drive shaft 45 is located in the center and movable in up and down direction in the drawing, and the stator 47 having coils 48 (not shown in the drawing) surrounds the drive shaft 45. In the example shown in Fig . HA, a pair of the magnetic force shields 60 are fixed on the material covering the stator 47 made from non-magnetic body ( e . g . , plastic) as integral portions of the unit linear motor 401. A variety of ways for fixing the magnetic force shields 60 onto the linear motor 40 may be conceivable, such as adhesion, inj ecting plastic integrally with a cover for the coils 48 , clip fixing at both upper and lower ends , etc .. The unit type linear motor 401 may be used by disposing adj acent linear motors 40 side by side with one of the magnetic force shields 60 of both linear motors 40 facing each other . Typical example is a case of the mounting head 4 or 14 shown in this embodiment in which adj acent linear motors 40 are disposed in close distance along one axis direction only. Although the example shown in HA shows a pair of magnetic force shield 60 integrally formed with the linear motor 40 , which are aligned parallel , they may be arranged non-parallel manner having an angle between each other . In this case, the unit type linear motor 401 may be applicable to the case in which the magnetic force shields 60 are arranged in radial pattern as shown in Fig . 1 OA. [ 0067 ]

Fig . HB shows a unit type linear motor 402 , in which the magnetic force shields 60 are formed in square pattern . In this example, a casing 51 made by non-magnetic body having a square cross section is formed around the linear motor 40, and magnetic force shields 60 are attached to four surfaces of such a casing 51. Although the example shown in Fig . HB includes magnetic force shields 60 arranged in square pattern, they may be arranged in rectangular pattern depending on distances between the adj acent linear motors 40 in vertical and horizontal directions . Some other irregular quadrangle pattern, such as trapezoidal pattern, diamond-shaped pattern, may also be possible . This type of unit type linear motor 402 may be used, for example, to the case where the linear motors 40 are laid out in checkered pattern as shown in Fig . 1 OB . [ 0068 ]

Fig . HC shows a unit type linear motor 403 in which the magnetic force shield 60 is formed in a cylindrical manner covering outer circumference of the linear motor 40. Basic configuration of this unit type linear motor 403 is similar to that of the unit type linear motor 402 as shown in Fig . HB, except the magnetic force shield 60 and the casing 51 are formed in cylindrical manner . Such a unit type linear motor 403 may be used for a case in which a plurality of linear motors 40 are disposed in polka-dotted pattern as shown in Fig . 1OC . The unit type linear motor 403 may also be used for the case as shown in Fig . 1 OA where magnetic shielding effect may not be achieved by a pair of magnetic force shields 60 disposed on opposite side of the linear motor 40 in radial pattern due to large relative angle between the pair of magnetic force shields 60. Cross section of the magnetic force shield 60 may not necessarily be in circular configuration, but can be in elliptical or other configuration, if required . Cross section of the magnetic force shield 60 may even be in square configuration similar to the magnetic force shield 60 shown in Fig . HB . [ 0069 ] In the examples shown in Figs . 11A-11C, the magnetic force shield 60 has a length in axial direction exactly the same as that of the stator 47 , but this is for illustrative purpose only, and the length could be made longer or shorter depending on stroke of the drive shaft 45 so as to cover magnetized portion of the drive shaft 45 in its full stroke .

[ 0070 ]

Description so far has been made relating to a structure for preventing interaction between magnetic forces generated by adj acent linear motors 40. However, linear motors 401-403 as shown in Figs l la-llc having the magnetic force shield 60 on outer circumference thereof may achieve unique effect even when such a unit type linear motors 401-403 is used independently . For example, in the environment where the linear motor is used, some other driving elements , such as actuators or feeders having magnets or components made from magnetic body, may move around or fixed closely to the linear motor . In such a case, there is a risk that the linear motor 40 may be affected by magnetic forces that are generated from such other elements , which may in turn cause undesirable condition for controlling and operating the linear motor 40. If the unit type linear motor 401-403 having magnetic force shield 60 as integral part thereof is used, smooth and desirable control or operation may be assured by preventing effects due to magnetic forces generated from magnets or coils of these other elements . At the same time, undesirable effect generated from magnets and coils of the linear motor 401-403 itself may also be blocked . [ 0071 ]

The shaft type linear motor, and the usage thereof according to the present invention has been described, but scope of the present invention is not limited thereto . For example, application of the present invention to the mounting head used for a component mounting machine is merely an example, and the present invention may also be similarly applied to a multiple axis actuator having a plurality of linear motors . Also the component mounting machine described above has a pair of mounting heads each may be operated independently from each other, but the present invention may also be applicable to an apparatus having a single mounting head, or having three or more mounting heads . Further, application of the present invention is not limited to XY robot type component mounting machine, but may be applicable to rotary type component mounting machine in which a plurality of nozzle assembly are arranged in a circular manner that are driven by an intermittently rotating index . In this specification, the term "robot for transferring the mounting head" should include such index type driving .

Claims

1. A multi-axis linear motor having a plurality of shaft type linear motors ( 40 ) each of which linear motors ( 40 ) comprising : a stator ( 47 ) having either permanent magnets ( 45a) or coils ( 48 ) aligned linearly, and movable portion ( 45) having either coils ( 48) opposed to said permanent magnets ( 45a) of said stator ( 47 ) , or permanent magnets ( 45a) opposed to said coils ( 48 ) of said stator ( 47 ) , capable to be driven relative to said stator ( 47 ) by applying driving electricity to said coils ( 48 ) , wherein, said multi-axis linear motor further comprising a magnetic force shield ( 60 ) for preventing magnetic interaction between the adj acent linear motors ( 40 ) .

2. A multi-axis linear motor according to claim 1 , wherein said linear motor ( 40 ) further comprising a magnetic force shield ( 60 ) on a side where no adj acent linear motor ( 40 ) exists .

3. A multi-axis linear motor according to claim 1 , wherein said magnetic force shields ( 60) are disposed radially between the adj acent linear motors ( 40 ) when said linear motors ( 40 ) are arranged in a circular manner on a plane perpendicular to axial direction of the linear motors ( 40 ) .

4. A multi-axis linear motor according to any one of the preceding claims , wherein the magnetic force shield ( 60 ) is made by a magnetic body .

5. A multi-axis linear motor according to claim 4 , wherein said magnetic body is a steel plate .

6. A multi-axis linear motor according to any one of the preceding claims, further comprising a position detecting sensor unit ( 49 ) for detecting moving position of a drive shaft ( 45 ) forming said movable portion by sensing magnitude of permanent magnets ( 45a) magnetized on said drive shaft ( 45 ) .

7. A mounting head ( 4 , 4a, 14 ) for picking up components supplied to component supply ( 8A-8C) , and mounting the same onto predetermined mounting positions of a circuit substrate ( 2 ) , comprising : a plurality of nozzles ( 39 ) for sucking components ; vacuum supply for supplying vacuum to said nozzles ( 39 ) ; and a multi-axis linear actuator for driving each of said plurality of nozzles ( 39) in their longitudinal direction, wherein, said multi-axis linear actuator comprising a multi axis linear motor ( 40 ) according to any one of the preceding claims .

8. A component mounting machine ( 101 ) for picking up a component and mounting the same onto a circuit substrate ( 2 ) , comprising : a component supply ( 8A-8C) for supplying components continuously; a mounting head for picking up components from said component supply ( 8A-8C) and mounting the same onto a circuit substrate ( 2 ) ; a robot ( 5, 15 ) for transferring said mounting head ( 4 , 40 ) ; a substrate holding/transferring device ( 3, 13 ) for feeding a circuit substrate ( 2 ) and holding the same ; and

^'a controller ( 100 ) for controlling over all operations of said component, mounting machine ( 101 ) , wherein, said mounting head comprising the mounting head ( 4 , 4a, 14 ) according to claim 7.

9. A component mounting machine ( 101 ) according to claim 8 , wherein the component mounting machine ( 101 ) includes a plurality of mounting heads ( 4 , 4a, 14 ) operable independently from each other .

10. A linear motors ( 401-403 ) comprising : a stator ( 47 ) having either permanent magnets ( 45a ) or coils ( 48 ) aligned linearly, and movable portion ( 45) having either coils ( 48 ) opposed to said permanent magnets ( 45a ) of said stator ( 47 ) , or permanent magnets ( 45a) opposed to said coils ( 48 ) of said stator ( 47 ) , capable to be driven relative to said stator ( 47 ) by applying driving electricity to said coils ( 48 ) , wherein, said linear motor ( 401-403 ) further comprising magnetic force shield ( 60 ) for preventing outward expansion of magnetic field generated by the magnets ( 45a) and/or coils ( 48 ) , which magnetic force shield ( 60 ) is fixed at each of two sides of circumference of the stator ( 47 ) opposing each other, and extends in axial direction of the linear motor ( 401-403 ) .

11. A linear motor ( 401-403 ) according to claim 10, wherein said magnetic force shields ( 60 ) fixed at two sides of the circumference of .the stator ( 47 ) are aligned substantially parallel to each other when viewed along axial direction of the linear motor ( 401-403 ) .

12. A linear motor ( 401-403 ) according to claim 10, comprising two pairs of magnetic force shields ( 60 ) each of which opposing each other .

13. A linear motor ( 401-403 ) according to claim 10 , wherein said two pairs of magnetic force shields ( 60 ) each of which opposing each other are arranged in a rectangular pattern when viewed on a plane perpendicular to axial direction of the linear motor ( 401-403 ) .

14. A linear motor ( 401-403 ) according to claim 10, wherein said magnetic force shield ( 60 ) is formed in a manner surrounding circumference of the linear motor ( 401- 403 ) in axial direction thereof .

15. A linear motor ( 401-403 ) according to claim 14 , wherein the configuration of said magnetic force shield

( 60 ) surrounding the circumference of the linear motor ( 401-403 ) is in circular or rectangular configuration when viewed on a plane perpendicular to axial direction of the linear motor ( 401-403 ) .

16. A linear motor ( 401-403 ) according to any one of claims 10-15, wherein the magnetic force shield ( 60 ) is formed by a magnetic body .

17. A multi axis linear motor, comprising a plurality of linear motors ( 401-403 ) according to any one of claims 10- 16.

18. A magnetic force shield ( 60 ) to be disposed between adj acently located linear motors ( 40 ) with their axial direction aligned parallel to each other, or fixed outer circumference of a linear motor ( 40 ) for preventing interaction of magnetic forces generated from magnets ( 45a) and/or coils ( 48 ) with other linear motors ( 40) , wherein said magnetic force shield ( 60 ) is formed by a sheet of a magnetic body .

19. A magnetic force shield ( 60 ) according to claim 18 , wherein said magnetic force shield ( 60 ) is made by a steel plate .

20. A method for shielding magnetic force for preventing interaction of the magnetic forces generated respective linear motors ( 40 ) forming a multi-axis linear motor so as to achieve desired control of adj acently disposed linear motors ( 40 ) independently from each other, wherein the method includes disposing a magnetic force shield ( 60 ) made from a magnetic body between the adj acent linear motors ( 40 ) .

21. A method of claim 20, wherein said magnetic body is a steel plate .