In a moving magnet type actuator, a magnet moving body including at least two permanent magnets of which same poles are confronting each other and an intermediate magnetic substance. The magnet moving body is movably arranged inside at least three coils. The at least three coils are connected so that current flows in different directions with a zone between the permanent magnets as a boundary. Whereby thrust and efficiency of the moving magnet type actuator is improved.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a moving magnet-type actuator for converting 
electrical energy into reciprocating kinetic energy or the like by 
electromagnetic action for use in control equipments, electronic 
equipments, machine tools and the like. 
2. Description of the Related Art 
Conventionally, moving magnet-type reciprocating devices have a structure 
such as shown in a first conventional example of FIG. 1 and a structure 
such as shown in a second conventional example of FIG. 2. 
In the first conventional example shown in FIG. 1, reference numeral 10 
designates a magnet moving body made of a bar-shaped permanent magnet 
magnetized in the axial direction. This bar magnet moving body has 
magnetic poles at both ends thereof. Coils 11A, 11B are wound around 
annularly the outer circumferences of both end portions of the magnet 
moving body 10 in such a manner that the same poles are generated at 
neighboring portions thereof. Although not shown in FIG. 1, the coils 11A, 
11B are usually installed into a nonmagnetic guide sleeve member for 
movably guiding the magnet moving body 10 in the axial direction. Magnetic 
flux from the respective end surfaces of the magnet moving body 10 links 
with the respective coils 11A, 11B. 
In the second conventional example shown in FIG. 2, a magnet moving body 15 
is formed by firmly integrating two bar-shaped permanent magnets 16A and 
16B with a bar-shaped magnetic substance 17 in such a manner that the same 
poles of the permanent magnets confront each other and that the magnetic 
substance is interposed between the permanent magnets. A coil 18 is wound 
annularly around the outer circumference of the middle portion of the 
magnet moving body 15. Although not shown in FIG. 2, the coil 18 is 
usually installed into a nonmagnetic guide sleeve member for movably 
guiding the magnet moving body 15 in the axial direction. Magnetic flux 
from the end surfaces of the permanent magnets with the same poles thereof 
confronting each other in the magnet moving body 15 links with the coil 
18. 
As the second conventional example shown in FIG. 2, the magnet moving body 
in which same poles of magnets are confronting each other is disclosed in 
U.S. Pat. No. 4,363,980. 
By the way, in the first and second conventional examples, a force to be 
generated at the magnet moving bodies 10 or 15 is produced based on the 
Fieming's left hand rule. The Fieming's left hand rule is applied to 
coils. Since the coils are fixed in the above cases, a thrust is produced 
at the magnet moving body as reaction against force acting on the coils. 
Therefore, what contributes to producing a thrust is a vertical component 
of the magnetic flux from the permanent magnets of the magnet moving body 
(the component perpendicular to the direction of magnetization of the 
permanent magnets). 
How the vertical component of the magnetic flux behaves was analyzed in two 
cases: a case where only one permanent magnet was used and a case where 
two permanent magnets arranged so that the same poles confront each other 
were used. 
FIG. 3 shows a result obtained from a magnetic field analysis of the 
vertical component of the surface magnetic flux density made along with 
the longitudinal side surface of a single permanent magnet. The permanent 
magnet used in the analysis was a rare-earth permanent magnet whose 
diameter was 2.5 mm and whose length was 6 mm. Measurements were made at 
positions 0.25 to 0.45 mm distant from the surface of the permanent 
magnet. 
FIGS. 4 to 7 show results obtained from magnetic field analysis of the 
vertical component of the surface magnetic flux density made along the 
longitudinal side surface of two permanent magnets in the cases where the 
two permanent magnets are arranged so that the same poles thereof confront 
each other with confronting gaps of 0, 1, 2, 3 mm, respectively. Each of 
the permanent magnets used was a rare-earth permanent magnet whose 
diameter was 2.5 mm and whose length was 3 mm. Measurements were made at 
positions 0.25 to 0.45 mm distant from the surface of the permanent 
magnets. 
FIG. 8 shows a result obtained from a magnetic field analysis of the 
vertical component of the surface magnetic flux density made along the 
longitudinal side surface of two permanent magnets in a case where the two 
permanent magnets are arranged so that the same poles thereof confront 
each other while interposing a 1 mm-long magnetic substance therebetween. 
Each of the permanent magnets used was a rare-earth permanent magnet whose 
diameter was 2.5 mm and whose length was 3 mm. Measurements were made at 
positions 0.25 to 0.45 mm distant from the surface of the permanent 
magnets. 
As described above, the force produced at the magnet moving body is based 
on the Fieming's left hand rule, and it is desired that the vertical 
component of the magnetic flux of the permanent magnets which cuts across 
the coils (the component perpendicular to the axial direction of the 
permanent magnets) be large in quantity. However, in the first 
conventional example shown in FIG. 1, the vertical component of the 
surface magnetic flux density is as shown in FIG. 3, verifying that the 
vertical component in the first conventional example was smaller compared 
with the cases where the two permanent magnets were arranged with the same 
poles thereof confronting each other such as shown in FIGS. 4 to 8. 
Therefore, it is limited the improvement of the thrust by the 
configuration of the first conventional example shown in FIG. 1. For 
example, a force F1 of only 4.7 (gf) was produced under the condition that 
the magnet moving body 10 was formed of a rare-earth permanent magnet of 
2.5 mm in diameter and 6 mm in length and that a current of 40 mA was 
applied to the two coils 11A, 11B so that the same poles can be generated 
at the neighboring portions of the coils 11A, 11B. 
On the other hand, in the second conventional example of FIG. 1, the magnet 
moving body 15 interposing the magnetic substance between the two 
permanent magnets with the same poles thereof confronting each other was 
used. The vertical component of the magnetic flux density in the second 
conventional example is as shown in FIG. 8, which indicates that the 
magnetic flux produced from the magnetic poles of the permanent magnets 
16A and 16B arranged so that the same poles thereof confront each other 
was larger than in the case of a single permanent magnet (see FIG. 3) or 
of only two permanent magnets (see FIGS. 4 to 7). However, it is only one 
coil that was involved in this configuration that surrounds the middle 
portion of the magnet moving body 15, and this configuration seems to 
leave the magnetic flux produced from the magnetic poles at both ends of 
the magnet moving body 15 not utilized effectively. It was thus difficult 
to improve thrust also in the second conventional example of FIG. 2. For 
example, in the second conventional example of FIG. 2, a force F2 of only 
5.6 (gf) was produced when the same power consumption as in the first 
conventional example was achieved under the condition that a current of 40 
mA was applied to the coil 18 while using a magnet moving body that Was 
formed by interposing a 1 mm-long magnetic substance between two 
rare-earth permanent magnets as the magnet moving body 15. The coil 18 was 
prepared so that the same power consumption as in the first conventional 
example of FIG. 6 could be obtained. Each of the two permanent magnets was 
2.5 mm in diameter and 3 mm in length (the performance of the rare-earth 
permanent magnet was the same as that of the first conventional example). 
If the magnet moving body is formed by combining a plurality of permanent 
magnets and magnetic substances, then these components must be unified 
with one another surely. Further, if the actuator is formed by arranging 
an output extracting pin or pins on the permanent magnets, it is desirable 
to eliminate unnecessary play of the magnet moving body and the output 
extracting pins. This point must therefore be taken into consideration. 
SUMMARY OF THE INVENTION 
The device has been made in view of the above circumstances. Accordingly, 
the object of the device is to provide a magnet moving-type actuator which 
can improve thrust and efficiency by using a magnet moving body formed of 
at least two permanent magnets with the same poles thereof confronting 
each other and effectively utilizing magnetic flux produced from the 
magnetic poles of the permanent magnets, which can fix the permanent 
magnets surely and assemble the magnet moving body easily, and which 
permits smooth movement of the magnet moving body. 
To achieve the above object, the invention is applied to a moving 
magnet-type actuator that includes a magnet moving body formed by 
interposing a magnetic substance between at least two permanent magnets 
with the same poles of the permanent magnets confronting each other. The 
magnet moving body is movably arranged inside at least three coils. The at 
least three coils are connected so that current flows in different 
directions with a zone between the poles of the permanent magnets as a 
boundary. 
Further, the permanent magnets and the intermediate substance may be 
enclosed in a nonmagnetic holder to form the magnet moving body. 
Furthermore, an output extracting pin may be provided on at least one outer 
end surface of the permanent magnets. The output extracting pin is 
slidably supported by a bearing member which is supported with a 
predetermined positional relationship with respect, to the three coils. 
Still further, the magnet moving body may be formed by fixing permanent 
magnets and an intermediate magnetic substance interposed between the 
permanent magnets on a through shaft body passing through the permanent 
magnets and the intermediate magnetic substance. 
The actuator of the invention may also be designed so that a sleeve-like 
magnetic substance is arranged on the outer circumference of the coils to 
form a magnetic circuit for increasing a magnetic flux component in a 
direction perpendicular to a direction in which the permanent magnets are 
magnetized. 
Further, outer end magnetic substances may be arranged on outer end 
surfaces of the permanent magnets positioned at both outer ends of the 
magnet moving body. 
Still further, a magnetic attracting body for attracting the magnet moving 
body may be arranged on at least one end of the nonmagnetic guide sleeve 
on which the at least three coils are fixed. 
Still further, springs for basing the magnet moving body back to end 
positions of the nonmagnetic guide sleeve or return permanent magnets for 
generating repulsive force against the magnet moving body may be arranged. 
The operational concept of the moving magnet-type actuator of the invention 
will be described with reference to a schematic configurational diagram of 
FIG. 9. In FIG. 9, a magnet moving body 3 is formed by integrating two 
cylindrical permanent magnets 5A and 5B with a cylindrical magnetic 
substance 6 firmly interposed between these permanent magnets 5A and 5B, 
the same poles of the permanent magnets confronting each other. This is a 
structure in which the vertical component of the magnetic flux density 
(the component perpendicular to the axial direction of the permanent 
magnets) is produced in large quantities as shown in FIG. 8. Coils 2A, 2B 
and 2C are wound around the outer circumference of the magnet moving body 
3 and are arranged so that magnetic flux from the magnetic pole of the 
left end of the permanent magnet 5A, from the ends of the permanent 
magnets 5A, 5B at which the same poles confront each other, and from the 
right end of the permanent magnet 5B cuts across these coils. These coils 
2A, 2B, 2C are connected so that current flows in different directions 
with a zone between the poles of the permanent magnets 5A, 5B as a 
boundary (the boundary in the zone between the magnetic poles does not 
necessarily coincide with the midpoint between the magnetic poles as long 
as the boundary stays at some point between the magnetic poles). Although 
not shown, the coils 2A, 2B, 2C are usually installed into a nonmagnetic 
guide sleeve for movably guiding the magnet moving body 3 in the axial 
direction. The positional relationship between the coils 2A, 2B, 2C and 
the magnet moving body 3 is such that the currents flowing through the 
respective coils are opposite to one another with the zone between the 
poles of the permanent magnets as a boundary in all the range along which 
the magnet moving body 3 can move. 
The structure of the magnet moving body 3 in FIG. 9 is such that the two 
permanent magnets are arranged so that the same poles thereof confront 
each other and the magnetic substance is interposed between the permanent 
magnets as shown in FIG. 8. The vertical component of the surface magnetic 
flux density in an area Q corresponding to the position of the magnetic 
substance in the case of FIG. 8 is better than in the cases of FIGS. 4 to 
7 in which no magnetic substance is used (the peak for a magnetic flux 
density of 0.3 T or more is wide and high.) 
As described above, the magnet moving body 3 formed by interposing the 
magnetic substance between the two permanent magnets 5A, 5B with the same 
poles of the permanent magnets confronting each other can increase the 
magnetic flux component perpendicular to the longitudinal direction of the 
magnet moving body 3, such magnetic flux component contributing to 
producing a force based on the Fieming's left hand rule. In addition, 
since the three coils 2A, 2B, 2C link with the magnetic flux from all the 
magnetic poles of the permanent magnets effectively, a large thrust that 
could have never been produced by the conventional examples can be 
produced by applying current to the three coils 2A, 2B, 2C so that a 
magnetic field of opposite polarity can be generated alternately. If the 
current applied to the respective coils is inverted, so is the direction 
of the thrust of the magnet moving body 3. When alternating current is 
applied, the magnet moving body 3 functions as a vibrator that repeats 
vibrating at a predetermined cycle. 
In the case of FIG. 9, a force F3 of 6.7 (gf) was produced when the same 
power consumption was achieved under the condition that a current of 40 mA 
was applied to the three coils 2A, 2B, 2C while using a magnet moving body 
formed by interposing a 1 mm-long magnetic substance between two 
rare-earth permanent magnets as the magnet moving body 3. The coils 2A, 
2B, 2C were prepared so that the same power consumption as in the first 
and second conventional examples of FIGS. 1 and 2 could be achieved. Each 
of the two permanent magnets was 2.5 mm in diameter and 3 mm in length 
(the performance of the rare-earth permanent magnet was the same as the 
one used in the first conventional example). The obtained thrust F3 was 
about 1.42 times the thrust produced in the first conventional example and 
about 1.2 times that produced by the second conventional example under the 
same power consumption. It is understood from this result that the magnet 
moving body 3 of FIG. 9 is much better than the first and second 
conventional examples. 
A curve (a) of FIG. 10 shows a relationship between the displacement in the 
axial direction and the thrust (gf) of the magnet moving body 3 in the 
case where a sleeve-like magnetic substance at outer circumference of 
coils is not provided in FIG. 9. In the graph of FIG. 10, the dimensions 
and characteristics of the permanent magnet was the same as in FIG. 8; the 
zero displacement was defined as a state in which the midpoint of the 
magnet moving body 3 coincides with the midpoint of the coil 2B in the 
middle; and the current flowing through each coil was 40 mA. 
As described above, the moving magnet-type actuator includes the magnet 
moving body formed of a structural body combining the permanent magnets 
arranged with the same poles thereof confronting each other. Therefore, 
the magnetic flux density component perpendicular to the direction of 
magnetization of the permanent magnets (the axial direction) can be 
increased to a sufficient degree. In addition, since the magnetic flux 
produced at all the magnetic poles of the permanent magnets can be 
utilized effectively, a thrust to be produced between the magnetic flux 
and the current flowing through the three coils wound around the outer 
circumference of the magnet moving body based on the Fieming's left hand 
rule can be sufficiently increased. Consequently, a large thrust can be 
produced by a small structure and a small current. 
Further, in the case of where the permanent magnets and the intermediate 
magnetic substance disposed between the permanent magnets are accommodated 
and fixed in the nonmagnetic sleeve holder, the magnet moving body can be 
made rigid. Consequently, it can be prevent the permanent magnets and the 
magnetic substance from separating from others, thereby improve the 
reliability thereof. 
Further, the output extracting pin is provided with the magnet moving body 
and the pin is slidably supported by the bearing member. This feature 
contributes to eliminating unnecessary play of the magnet moving body and 
the output extracting pin and to ensuring the operational stability by 
permitting the pin to slide smoothly in the axial direction. 
Furthermore, the magnet moving body is formed by fixing the permanent 
magnets and the magnetic substance interposed between the permanent 
magnets on the through shaft body that passes through both the permanent 
magnets and the magnetic substance. As a result of the configuration, the 
permanent magnets and the magnetic substance can be fixed surely on the 
through shaft body, thus facilitating the assembling work therefor. In 
addition, the through shaft body is supported slidably, so that the magnet 
moving body can move inside the respective coils smoothly without play. 
The ends of the through shaft body can be used as output extracting pins. 
Furthermore, the outer end magnetic substances are provided on both outer 
ends of the magnet moving body, so that the magnetic flux component 
perpendicular to the longitudinal direction of the magnet moving body is 
increased. Such magnetic flux component contributes to produce a forth 
based on the Fieming's left hand rule, so that a much larger thrust can be 
obtained. 
Still furthermore, according to the configuration of the present invention, 
a force which acts in a direction perpendicular to a direction of the 
thrust (moving direction of the magnet moving body) can be made extremely 
small.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Moving magnet-type actuators, which are embodiments of the invention, will 
hereunder be described. 
FIGS. 11 and 12 show a first embodiment of the invention. In FIGS. 11 and 
12, reference numeral 1 designates a sleeve-like magnetic substance. Three 
coils 2A, 2B, 2C are disposed inside the sleeve-like substance 1 and are 
secured to the sleeve-like substance 1 by a nonmagnetic member such as a 
resin that constitutes a nonmagnetic guide sleeve 4 for slidably guiding a 
magnet moving body 3. The magnet moving body 3 includes: two cylindrical 
rare-earth permanent magnets 5A, 5B arranged with the same poles thereof 
confronting each other; and a cylindrical magnetic substance 6 that is 
secured between these permanent magnets 5A, 5B. These permanent magnets 
5A, 5B and the cylindrical magnetic substance 6 are unified with one 
another by an adhesive or the like. The three coils 2A, 2B, 2C are 
connected so that current flows in directions different from one another 
with a zone between the magnetic poles of the permanent magnets 5A, 5B as 
a boundary. That is, the coil 2B in the middle is arranged so as to 
enclose both the cylindrical magnetic substance 6 and the end portions of 
the permanent magnets 5A, 5B including the N-poles; and the coils 2A, 2C 
on both ends, to enclose the end portions of the permanent magnets 5A, 5B 
including the S-poles, respectively. The direction of the current flowing 
through the coil 2B in the middle opposes the direction of the current 
flowing through the coils 2A, 2C on both ends (see N and S indicated in 
each coil in FIG. 11). According to the present invention, rare-earth 
permanent magnet whose maximum energy product (BH-max) of 18 MGOe (=140 
KJ/m.sup.3) or more is used for the cylindrical permanent magnets 5A, 5B 
in order to obtain sufficient thrust. Thickness of the intermediate 
magnetic substance 6 disposed between the permanent magnets 5A, 5B is set 
0.1 to 1.0 times of the length of the permanent magnets. As reason of 
this, if the thickness of the intermediate magnetic substance 6 is too 
thin, a repulsive force becomes strong so that it is difficult to 
manufacture the magnet moving body, whereas if the thickness of the 
intermediate magnetic substance 6 is too thick, it is causes a problem in 
a movement of the magnet moving body in high frequency. Additionally, with 
respect to a diameter of the coil, a high thrust is obtained when an outer 
diameter of the coil is selected in a range of 1.2 to 3.5 times of a 
diameter of the permanent magnet, as shown in FIG. 32. A pin 9 or the like 
can be attached to the outer end surface of the permanent magnet 5A or 5B 
as indicated by a phantom line in FIG. 1. The pin serves as transmitting a 
thrust to an external destination as necessary. If this embodiment is used 
as a vibrator for pocket bells, no pin 9 is required. 
In the first embodiment, the sleeve-like magnetic substance 1 is arranged 
on the outer circumference of the respective coils 2A, 2B, 2C. A vertical 
component of the surface magnetic flux density of the magnet moving body 3 
is analyzed. 
FIG. 13 shows a result obtained from a magnetic field analysis of the 
vertical component of the surface magnetic flux density made along the 
longitudinal side surface of two permanent magnets in a case where the two 
permanent magnets are arranged so that the same poles thereof confront 
each other while interposing a 1 mm-long magnetic substance therebetween 
and arranging a sleeve-like magnetic substance facing against the outer 
circumference of the two permanent magnets. Each of the permanent magnets 
used was a rare-earth permanent magnet whose diameter was 2.5 mm and whose 
length was 3 mm. The sleeve-like magnetic substance enclosed the permanent 
magnets and was 0.5 mm thick and 10 mm long. The sleeve-like magnetic 
substance was positioned 1.25 mm away from the outer circumference of the 
permanent magnets. Measurements were made at positions 0.25 to 0.45 mm 
distant from the surface of the permanent magnets. 
In the first embodiment, since the sleeve-like magnetic substance 1 is 
arranged on the outer circumference of the respective coils 2A, 2B, 2C, 
the vertical component of the surface magnetic flux density of the magnet 
moving body 3 further increases as shown in FIG. 13. Such an increase 
allows the magnetic flux component perpendicular to the longitudinal 
direction of the magnet moving body 3 to increase, such component 
contributing to producing a thrust based on the Fieming's left hand rule. 
Therefore, if current is applied to the three coils 2A, 2B, 2C that are 
wound annularly around the outer circumference of the magnet moving body 3 
so that a magnetic field of opposite polarity is generated alternately, 
then a larger thrust can be produced. For example, a thrust F4 of 8.0 (gf) 
was produced when the same power consumption was achieved under the 
condition that a current of 40 mA was applied to three coils 2A, 2B, 2C 
while using a magnet moving body formed by interposing a 1 mm-long 
magnetic substance interposed between two rare-earth permanent magnets as 
the magnet moving body 3. The coils 2A, 2B, 2C were prepared so that the 
power consumption became the same as in the first and second conventional 
examples shown in FIGS. 1 and 2. Each of the two permanent magnets was 2.5 
mm in diameter and 3 mm in length (the performance of the rare-earth 
permanent magnet was the same as the one used in the first conventional 
example). The direction of the thrust F4 is such that the magnet moving 
body 3 moves rightward under the polarity shown in FIG. 11. By inverting 
the current to be applied to each coil, the direction of the thrust 
produced by the magnet moving body 3 is inverted. When alternating current 
is applied, the embodiment functions as a vibrator that repeats vibrating 
at a predetermined cycle is applicable with applicable to a pocket-bell 
device. 
A curve (b) of FIG. 10 shows a relationship between the axial displacement 
and the thrust (gf) of the magnet moving body 3 in the case of the first 
embodiment (the dimensions and arrangement of the permanent magnets and 
the sleeve-like magnetic substance as well as the characteristics of the 
permanent magnets are as shown in FIG. 13). The relationship refers to a 
movement of the magnet moving body 3 in the direction of leaving the zero 
displacement point. A curve (c) shows a relationship between the axial 
displacement and the thrust (gf) of the magnet moving body 3 in the case 
of the sleeve-like magnetic substance is provided in the first embodiment. 
The relationship refers to a movement of the magnet moving body 3 in the 
direction of nearing the zero displacement point. However, the zero 
displacement was defined as a state in which the midpoint of the magnet 
moving body 3 coincides with the midpoint of the coil 2B in the middle, 
and the current flowing in each coil was 40 mA. Accordingly, the reason 
why the thrusts are different depending on the magnet moving body 3 moving 
closer to the zero displacement point or moving away from the zero 
displacement point is that magnet attracting force acts between the 
magnetic poles of the permanent magnets of the magnet moving body 3 and 
the sleeve-like magnetic substance 1 so that the magnet moving body 3 
returns to the zero displacement point. 
FIG. 14 shows a second embodiment of the invention. In the second 
embodiment, attracting plates 8A, 8B made of a magnetic substance are 
fitted into and secured to both ends of a sleeve-like magnetic substance 1 
and of a nonmagnetic guide sleeve 4. A pin 9 secured to an outer end 
surface of a permanent magnet 5A projects from a hole provided on one 
attracting plate 8A. Other structural aspects of the second embodiment are 
the same as those of the first embodiment. 
In the case of the second embodiment, the permanent magnet is attracted by 
either one of the magnetic attracting plates 8A, 8B when the coils 2A, 2B, 
2C are not in conduction. If a thrust is produced in the direction of an 
arrow R by energizing the coils 2A, 2B, 2C so that a magnetic field of 
opposite polarity is generated alternately in each of the coils 2A, 2B, 2C 
with the magnet moving body 3 staying at a position shown in FIG. 3, then 
the magnet moving body 3 moves in the direction of the arrow R by leaving 
the attracting plate 8A and stops while attracted by the attracting plate 
8B. If, on the other hand, a thrust whose direction is opposite to that of 
the arrow R is produced by inverting the current in each of the coils 2A, 
2B, 2C, then the magnet moving body 3 leaves the attracting plate 8B, 
moves toward the attracting plate 8A, and stops while attracted by this 
attracting plate 8A. Thus, the attracting plates 8A, 8B contribute to 
regulating the range of movement of the magnet moving body 3 accurately. 
Further, while the attracting plates 8A, 8B made of a magnetic substance 
are arranged on both sides of the sleeve-like magnetic substance 1 and the 
nonmagnetic guide sleeve 4 in the second embodiment, such a structure that 
the attracting plate is arranged only on one side of the sleeve-like 
magnetic substance 1 and the nonmagnetic guide sleeve 4 may also be 
applicable. 
FIGS. 15 and 16 show a third embodiment of the present invention. In third 
embodiment, the magnet moving body 3 includes: two cylindrical rare-earth 
permanent magnets 5A, 5B arranged with the same poles thereof confronting 
each other; a cylindrical magnetic substance 6 that is secured between 
these permanent magnets 5A, 5B and a nonmagnetic sleeve-like holder 7. 
These permanent magnets 5A; 5B and the magnetic substance 6 are 
accommodated in the nonmagnetic sleeve-like holder 7 and unified with one 
another by an adhesive or the like. Other structures are the same as the 
above mentioned first embodiment. 
In third embodiment, the permanent magnets 5A, 5B and the intermediate 
magnetic substance 6 are accommodated and fixed in the nonmagnetic 
sleeve-like holder 7. This configuration prevents the permanent magnets 
from being separated from each other due to repulsive force derived from 
the same poles thereof that confront each other, thus contributing to 
making the structure of the magnet moving body 3 rigid and improving the 
reliability thereof while preventing breakage or wear of the permanent 
magnets. Assembling accuracy can also be improved. 
FIG. 17 shows a fourth embodiment of the invention. In this case, a magnet 
moving body 3A includes: two cylindrical rare-earth permanent magnets 5A, 
5B arranged with the same poles thereof confronting each other; a 
cylindrical magnetic substance 6 interposed between these permanent 
magnets 5A, 5B; nonmagnetic members 9, each having a pin, arranged on the 
outer end surfaces of the respective permanent magnets; and a nonmagnetic 
sleeve-like holder 7A. The permanent magnets 5A, 5B, the magnetic 
substance 6, and the disc-like bases of the members 9 with pins are 
accommodated in the nonmagnetic sleeve-like holder 7A and fixed therein by 
an adhesive or the like. Further, attracting plates 8A, 8B are fitted into 
and secured to both end portions of a sleeve-like magnetic substance 1 
made of a magnetic substance and a nonmagnetic guide sleeve 4. The pin 
portions of the members 9 secured to the outer end surfaces of the 
permanent magnets 5A, 5B project from holes provided on the attracting 
plates 8A, 8B. The pin portions of the members 9 are slidable through the 
holes of the attracting plates 8A, 8B. Other structural aspects of the 
fourth embodiment is the same as those of the first embodiment. 
In the case of the fourth embodiment, the magnet moving body 3A is 
attracted by either one of the magnetic attracting plates 8A, 8B when the 
coils 2A, 2B, 2C are not in conduction. If the magnet moving body 3A is in 
a shown condition, a thrust is produced in the direction of an arrow R by 
energizing the coils 2A, 2B, 2C so that a magnetic field of opposite 
polarity can be generated alternately. As a result, the magnet moving body 
3A leaves the attracting plate 8A, moves in the direction of the arrow R, 
and stops while attracted by the attracting plate 8B. If, on the other 
hand, a thrust is produced in the direction opposite to the arrow R by 
inverting the current to be applied to the coils 2A, 2B, 2C, then the 
magnet moving body 3A leaves the attracting plate 8B, moves toward the 
attracting plate 8A, and stops while attracted by the attracting plate 8A. 
Accordingly, the presence of the attracting plates 8A, 8B contributes to 
accurately regulating the range of movement of the magnet moving body 3A, 
thereby allowing the movement of the magnet moving body 3A to be 
transmitted to an external destination through the members 9 with pins. 
FIG. 18 shows a modified example of the magnet moving body applicable to 
the third embodiment. A magnet moving body 3B of this example includes: 
two cylindrical rare-earth permanent magnets 5A, 5B; a cylindrical 
magnetic substance 6 interposed between these permanent magnets 5A, 5B; 
and a nonmagnetic sleeve-like holder 7B. The permanent magnets 5A, 5B and 
the magnetic substance 6 are accommodated in the sleeve-like holder 7B. 
These components constituting the magnet moving body are fixed and 
integrated with one another by caulking the end portions of the 
sleeve-like holder 7B. According to this structure, the rate of production 
of magnet moving bodies can be improved. 
The magnet moving body formed by accommodating the permanent magnets 5A, 
5B, the magnetic substance 6, and the disc-like bases of the members 9 
with pins, and fixing and integrating these components by caulking the end 
portions of the sleeve-like holder may be used also in the fourth 
embodiment. 
Still further, while the magnetic attracting plates 8A, 8B are arranged on 
both ends of the sleeve-like magnetic substance 1 and the nonmagnetic 
guide sleeve 4 and the members 9 with pins are provided on the outer end 
surfaces of the both permanent magnets 5A, 5B in the fourth embodiment, 
such a structure that the attracting plate and the member with a pin are 
provided only on one side of the magnet moving body may also be applied. 
FIGS. 19 and 20 show a fifth embodiment of the present invention. In the 
fifth embodiment, the magnet moving body 3 includes: two cylindrical 
rare-earth permanent magnets 5A, 5B arranged with the same poles thereof 
confronting each other; a cylindrical magnetic substance 6 that is secured 
between these permanent magnets 5A, 5B, and an output extracting pin 9 
fixed on outer end surface of the permanent magnets 5A, 5B. These 
permanent magnets 5A, 5B, the magnetic substance 6, and the output 
extracting pin are integrated with one another by an adhesive or the like. 
The output extracting pin 9 may be either magnetic or nonmagnetic. 
Further, side plates 8A, 8B made of a nonmagnetic substance are fitted into 
and secured to both ends of the sleeve-like magnetic 1 and the nonmagnetic 
guide sleeve 4. Sleeve-like bearing members 20 made of a metal such as 
brass, or a highly slidable resin, etc. are supported in the middle of the 
side plates 8A, 8B, respectively. The pin portions 9A of the members 9 
with pins which are secured to the outer end surfaces of the permanent 
magnets 5A, 5B are slidably supported by the inner surfaces of the 
sleeve-like bearing members 20, with the pin portions 9A projecting from 
the bearing members. The other structures are the same as the above 
mentioned first embodiment. 
In the fifth embodiment, the members 9 with pins integrated with the magnet 
moving body 3 are slidably supported by the bearing members 20. This 
configuration can regulate the magnet moving body 3 so as to be concentric 
with the central axis of the nonmagnetic guide sleeve 4 at all times, thus 
preventing unnecessary play of the magnet moving body 3 as well as the 
members 9 with pins. In addition, the magnet moving body 3 is not brought 
into contact with the inner circumferential surface of the magnetic guide 
sleeve 4, so that the magnet moving body 3 can move smoothly in the axial 
direction, which in turn eliminates, e.g., wear of the magnet moving body 
3 and the nonmagnetic guide sleeve 4. 
FIG. 21 shows a modified example of the magnet moving body used in the 
fifth embodiment. In this case, a magnet moving body 3A is formed by 
interposing a cylindrical magnetic substance 6 between two permanent 
magnets 5A, 5B with the same poles of the permanent magnets confronting 
each other, accommodating these components in a nonmagnetic sleeve-like 
holder 7, arranging members 9 with output extracting pins on outer end 
surfaces of the permanent magnets 5A, 5B, and fixing disc-like bases 9B of 
such members 9 with pins on both end portions of the sleeve-like holder 7. 
The permanent magnets 5A, 5B, the cylindrical magnetic substance 6, and 
the members 9 with pins may be fixed on the sleeve-like holder 7 by an 
adhesive or the like, or by caulking the end portions of the sleeve-like 
holder 7. 
In the above-described embodiment, the side plates 8A, 8B may be made of a 
magnetic material so that the side plates can function as the attracting 
plates. In this case, the magnet moving body 3 is attracted by either one 
of the magnetic side plates 8A, 8B when the coils 2A, 2B, 2C are not in 
conduction. If a thrust is produced at the coils 2A, 2B, 2C in the 
direction of the magnet moving body 3 leaving the side plate by which the 
magnet moving body 3 is attracted, then the magnet moving body 3 moves 
toward the opposite side plate and stops while attracted by such opposite 
side plate. 
While the magnet moving body 3 including two permanent magnets arranged 
with the same poles thereof confronting each other and the magnetic 
substance interposed therebetween has been exemplified in the 
above-described embodiments, a magnet moving body such as including three 
or more permanent magnets with the same poles thereof confronting each 
other and magnetic substances interposed therebetween may be applicable. 
In this case, the number of coils can be increased to four or more to 
match the increase in the number of permanent magnets. 
Still further, while the magnet moving body 3 is provided with the members 
with pins on both sides thereof, the member 9 with a pin may be arranged 
only on one side thereof. In this case, the bearing member is provided 
only on one side (the length of the bearing member 20 is preferably longer 
in this case). 
FIGS. 22A and 22B show a sixth embodiment of the present invention. In this 
embodiment, the magnet moving body 3 includes: two cylindrical rare-earth 
permanent magnets 5A, 5B arranged with the same poles thereof confronting 
each other; a cylindrical intermediate magnetic substance 6A that is 
secured between these permanent magnets 5A, 5B; and cylindrical outer end 
magnetic substances 6B, 6C secured to the outer end surfaces of the 
permanent magnets 5A, 5B. These permanent magnets 5A, 5B and the magnetic 
substances 6A, 6B, 6C are integrated with one another by an adhesive or 
the like. In this embodiment, a thickness of the outer end magnetic 
substances are designed about half to same (1/2 to 1) of that of the 
intermediate magnetic substance 6A. The other structures are the same as 
the above mentioned first embodiment. 
FIG. 23 shows a result obtained from a magnetic field analysis of the 
vertical component of the surface magnetic flux density made along the 
longitudinal side surface of two permanent magnets when the two permanent 
magnets were arranged so that the same poles thereof confront each other 
while interposing the magnetic substance between the permanent magnets and 
disposing magnetic substances on outer end surfaces of the permanent 
magnets. 
The structure of the magnet moving body 3 in FIG. 23 is such that the two 
permanent magnets are arranged so that the same poles thereof confront 
each other; the intermediate magnetic substance is interposed between the 
permanent magnets; and the outer end magnetic substances are arranged on 
the outer end surfaces of the permanent magnets as shown in FIG. 23. The 
vertical component of the surface magnetic flux density in an area 
corresponding to the positions of the outer end magnetic substances in the 
case of FIG. 23 is better than in the case of FIG. 8 in which no outer end 
magnetic substances are used (it goes without saying that the vertical 
component of the surface magnetic flux density is better than in the case 
of FIG. 3 in which only one permanent magnet is used.) 
As described above, the magnetic moving body 3 formed by arranging the two 
permanent magnets 5A, 5B with the same poles thereof confronting each 
other, interposing the intermediate magnetic substance 6A between the 
permanent magnets 5A, 5B, and arranging the outer end magnetic substances 
6B, 6C on the outer end surfaces of the permanent magnets 5A, 5B can 
further increase the magnetic flux component perpendicular to the 
longitudinal direction of the magnet moving body 3, such magnetic flux 
component contributing to producing a thrust based on the Fieming's left 
hand rule. In addition, since the three coils 2A, 2B, 2C cut across the 
magnetic flux from all the magnetic poles of the permanent magnets 
effectively, a large thrust can be produced by applying current to the 
three coils 2A, 2B, 2C in such a manner that a magnetic field of opposite 
polarity is generated alternately. Such thrust can never be produced by 
the conventional example of FIG. 1, and will be larger than the thrust 
produced by the first embodiment shown in FIG. 11. 
Two rare-earth permanent magnets which is 2.5 mm in diameter and 3 mm in 
length (the performance of the rare-earth permanent magnet was the same as 
the one used in the first conventional example), an intermediate magnetic 
substance which is 1 mm in length and is interposed between the permanent 
magnets, and outer end magnetic substances disposed on the outer end 
surface of the permanent magnets are used to form a magnet moving body 3. 
Additionally, a sleeve-like magnetic substance 1 are provided at 
outercircumstance of the three coils. By this arrangement of the actuator, 
when 40 mA current is applied into the tree coils 2A, 2B, 2C so as to be 
the same power consumption as in the first conventional example, then a 
force F4 of 8.6 (gf) is generated. Comparison of embodiments and the 
conventional example is shown in the following table. 
______________________________________ 
Sleeve No sleeve 
magnetic 
magnetic 
substance 
substance 
______________________________________ 
First conventional example; 
5.4 gf 4.7 gf 
(Single magnet & 2 coils; FIG. 1) 
First Embodiment; 8.0 gf 6.7 gf 
(2 magnets & intermediate magnetic 
substance & 3 coils); FIG. 11) 
Sixth Embodiment; 8.6 gf 7.3 gf 
(2 magnets & intermediate magnetic 
substance & 2 outer end magnetic 
substance & 3 coils) 
______________________________________ 
An output extracting pin 9 may be arranged on the outer end magnetic 
substance 6B or 6C as shown by a phantom line of FIG. 22A so that the 
thrust can be transmitted to an external destination. In the case where 
the embodiment is used as a vibrator for a pocket bell or the like, no pin 
9 is required. 
A magnetic attracting plate or plates 8A, 8B may be fixed on either one or 
both end portions of the sleeve-like magnetic substance 1 as shown by a 
phantom line of FIG. 22a so that the range of movement of the magnet 
moving body 3 can be regulated. In this case, the magnet moving body 3 
stops while attracted by the magnetic attracting plates 8A, 8B. 
FIG. 24 shows a seventh embodiment of the invention. In FIG. 24, a magnet 
moving body 3 accommodates two cylindrical rare-earth permanent magnets 
5A, 5B, a cylindrical intermediate magnetic substance 6A interposed 
between these permanent magnets 5A, 5B, and cylindrical outer end magnetic 
substances 6B, 6C arranged on outer end surfaces of the permanent magnets 
5A, 5B in a nonmagnetic sleeve-like holder 7. These components are 
integrated with one another by caulking the end portions of the holder 7, 
by being bonded to the holder 7, or like means. Nonmagnetic pins 25 are 
integrally formed on the outer end magnetic substances 6B, 6C of the 
magnet moving body 3. That is, the nonmagnetic pins 25 are firmly 
integrated with the flat cylindrical outer end magnetic substances 6B, 6C 
in the middle thereof by welding, bonding, or like means. On the other 
hand, support plates 28 are secured to both end portions of a sleeve-like 
magnetic substance 1 and a nonmagnetic guide sleeve 4. The nonmagnetic 
pins 25 pass through central holes of the support plates 28. Both 
nonmagnetic pins 25 are slidably supported by the central holes 26. 
Annular permanent magnets 27 are fixed on the inner surfaces of the 
support plates 28, respectively, so that repulsive force can be produced 
between the magnetic poles of the annular permanent magnets 28 and the 
magnetic poles on the outer end surfaces of the permanent magnets 5A, 5B. 
For example, in FIG. 24, the S-poles of the outer end surfaces of the 
permanent magnets 5A, 5B confront the S-poles of the annular permanent 
magnets 27. Other configurational aspects of the this embodiment are the 
same as those of the sixth embodiment. 
According to the seventh embodiment, the magnet moving body 3 is positioned 
to the middle of the sleeve-like magnetic substance 1 because of the 
repulsive force derived from the permanent magnets 5A, 5B and the annular 
permanent magnets 27 on right and left when the coils 2A, 2B, 2C are not 
energized. By applying direct current to the coils 2A, 2B, 2C, the magnet 
moving body 23 is driven to one side. When alternating current is applied 
to the coils, the magnet moving body 23 functions as a vibrator by the 
reciprocating operation thereof. However, when having made a certain 
displacement, the magnet moving body 3 is made to return to the middle 
position by the repulsive force derived from the permanent magnets 5A, 5B 
and the annular permanent magnets 27 on right and left. As a result, noise 
due to collision of the magnet moving body 3 against the support plates 28 
and the annular permanent magnets 27 can be prevented. Further, since the 
permanent magnets 5A, 5B and the magnetic substances 6A, 6B, 6C are 
accommodated integrally in the holder 7, the reliable integration of these 
components, the improvement of durability, and the increase in service 
life can be achieved. 
FIG. 25 shows an eighth embodiment of the invention. In FIG. 25, the outer 
end magnetic substances 6B, 6C of the magnet moving body 3 are provided 
with pins (the pines may be made of either a nonmagnetic or magnetic 
substance) 25A so as to be integral with one another. That is, the pins 
25A are secured to and integrated with the central portions of the outer 
end magnetic substances 6B, 6C by welding, bonding, or like means, or 
unitized with the outer end magnetic substances themselves. On the other 
hand, support plates 28 are secured to both end portions of a sleeve-like 
magnetic substance 1 and a nonmagnetic guide sleeve 4, and the pins 25A 
pass through central holes 26 of the support plates 28. Both pins 25A are 
slidably supported by the central holes 26.. Compression springs 29 are 
interposed between the outer end magnetic substances 6B, 6C and the inner 
surfaces of the support plates 28, respectively. Other configurational 
aspects of this embodiment are the same as those of the seventh 
embodiment. 
According to the eighth embodiment, the magnet moving body 3 is returned to 
the middle position of the sleeve-like magnetic substance 1 by the 
resilient force of the compression spring 29 on right and left when the 
coils 2A, 2B, 2C are not energized, whereas the magnet moving body 3 is 
driven to one side by applying direct current to the coils 2A, 2B, 2C. 
When alternating current is applied to the coils, the magnet moving body 3 
functions as a vibrator by the reciprocating operation thereof. However, 
when having made a certain displacement, the magnet moving body 3 is made 
to return to the middle position by the resilient force of the compression 
springs 29. As a result, noise due to collision of the magnet moving body 
3 against the support plates 28 can be prevented. 
FIGS. 26 and 27 show a ninth embodiment. In these Figures, reference 
numeral 1 designates a sleeve-like magnetic substance. Three coils 2A, 2B, 
2C are arranged inside the sleeve-like magnetic substance 1 and are 
secured to the sleeve-like substance 1 by a nonmagnetic member such as an 
insulating resin that constitutes a nonmagnetic guide sleeve 4 for 
slidably guiding a magnet moving body 3. The inner surface of the 
nonmagnetic guide sleeve 4 forms an inner circumferential surface. 
The magnet moving body 3 includes: two hollow cylindrical rare-earth 
permanent magnets 5A, 5B arranged with the same poles thereof confronting 
each other; a hollow cylindrical intermediate magnetic substance 6 
interposed between these permanent magnets 5A, 5B; and hollow disc-like 
cushion plates 27A, 27B arranged on the outer end surfaces of the 
permanent magnets 5A, 5B with a through shaft body 8 made of a metal being 
inserted therethrough. The through shaft body 8 is held by causing 
clampers (E rings made of a metal) 20 to be fitted into fitting grooves 29 
of the through shaft body 8, so that the permanent magnets 5A, 5B, the 
intermediate magnetic substance 6, and the disc-like cushion plates 27A, 
27B are fixed on the metallic through shaft body 8. The through shaft body 
8 is made of either a nonmagnetic or magnetic metal. The cushion plates 
27A, 27B are made of an elastic material such as silicon rubber, and are 
interposed between a pair of clampers 20 while compressed slightly. As a 
result, the cushion plates 27A, 27B can absorb variations in the thickness 
of the respective permanent magnets 5A, 5B and the magnetic substance 6, 
thereby preventing play of these components. An adhesive may additionally 
be used to integrate the metallic through shaft body 8 with the permanent 
magnets 5A, 5B and the magnetic substance 6. 
The three coils 2A, 2B, 2C are connected so that current flows in different 
directions with a zone between the magnetic poles of the permanent magnets 
5A, 5B as a boundary. That is, the coil 2B in the middle is wound 
annularly so that both the magnetic substance 6 and the end portions of 
the permanent magnets 5A, 5B including the N-poles are enclosed; whereas 
the coils 2A, 2C on both ends are wound annularly so that the end portions 
of the permanent magnets 5A, 5B including the S-poles are enclosed. The 
direction of the current flowing through the coil 2B in the middle opposes 
the direction of current flowing through the coils 2A, 2C on both ends 
(see N and S indicated in each coil in FIG. 26). 
Further, side plates 21A, 21B made of a nonmagnetic substance are fitted 
into and secured to both ends of the sleeve-like magnetic substance 1 and 
the nonmagnetic guide sleeve 4. Sleeve-like bearing members 22 made of a 
sintered metal, a highly slidable resin or the like are supported in the 
middle of the side plates 21A, 21B, respectively. The through shaft body 8 
passing through and integrated with the permanent magnets 5A, 5B and the 
magnetic substance 6 is slidably supported by the inner surfaces of the 
sleeve-like bearing members 22. One end of the through shaft body 8 
projects from the bearing member so that such end can be used as an output 
pin. The side plates 21A, 21B have projecting portions 23 that are fitted 
into the inner circumferential surfaces of the nonmagnetic guide sleeve 4, 
so that the front ends of the projecting portions 23 can regulate the 
range of movement of the magnet moving body 3 while abutting against the 
cushion plates 27A, 27B when the magnet moving body 3 is moving. The 
bearing members 22 may be either nonmagnetic or magnetic. 
Further, the magnet moving body 3 is formed by inserting the metallic 
through shaft body 8 into the hollow cylindrical rare-earth permanent 
magnets 5A, 5B, the hollow cylindrical intermediate magnetic body 6, and 
the hollow disc-like cushion plates 27A, 27B; and fitting the fasteners 20 
into the fitting grooves 29 of the metallic through shaft body 8 for 
holding. As a result of this configuration, the permanent magnets 5A, 5B 
and the intermediate magnetic body 6 can be fixed and integrated with one 
another reliably, which facilitates the assembling work therefor. 
Further, the through shaft body 8 integrated with the magnet moving body 3 
is slidably supported by the bearing members 22. This configuration can 
regulate the magnet moving body 3 so as to be concentric with the central 
axis of the nonmagnetic guide sleeve 4 at all times without allowing the 
magnet moving body 3 to play. In addition, the gap between the outer 
circumference of the permanent magnets 5A, 5B and the coils 2A, 2B, 2C can 
be set to a necessary minimum without having to cover a holder or the like 
on the outer circumference of the permanent magnets for the integration of 
the permanent magnets 5A, 5B and the magnetic body 6 thereby contributing 
to, effectively improving the thrust. Still further, the magnet moving 
body 3 is not brought into contact with the inner circumferential surface 
of the nonmagnetic guide sleeve 4, so that the magnet moving body 3 can 
move smoothly in the axial direction, which in turn eliminates, e.g., wear 
of the magnet moving body 3 and the nonmagnetic guide sleeve 4. 
In the configuration of the ninth embodiment, if either one or both of the 
side plates 21A. 21B on both outer ends are made of a magnetic substance, 
then the side plate or plates formed of the magnetic substance can serve 
as a magnet attracting body that attracts the magnet moving body 3. 
If, e.g., both of the side plates 21A, 21B are made of a magnetic 
substance, then the magnet moving body 3 is attracted and held by either 
one of the side plates when the coils 2A, 2B, 2C are not energized. If a 
thrust is produced by the coils 2A, 2B, 2C so that the magnet moving body 
3 moves to leave the side plate by which the magnet moving body 3 is 
attracted, then the magnet moving body 3 moves to the opposite side plate 
and stops while attracted by such opposite side plate. 
Further, if only one of the side plates is made of a magnetic substance, 
then it can be set so that the magnet moving body 3 is attracted and held 
by such one of the side plates at all times. 
FIG. 28 shows a tenth embodiment of the invention. In FIG. 28, nonmagnetic 
side plates 21C, 21D are fitted into and secured to both ends of a 
sleeve-like magnetic substance 1 and of a nonmagnetic guide sleeve 4. 
Compression springs 24 are arranged between the inner surfaces of the side 
plates 21C, 21D and the disc-like cushion plates 27A, 27B on the sides of 
the magnet moving body 3. The compression springs 24 bias the magnet 
moving body 3 back to the middle position. Other configurational aspects 
of the tenth embodiment are the same as those of the ninth embodiment. 
According to the tenth embodiment, the magnet moving body 3 is returned to 
the middle position of the sleeve-like magnetic substance 1 because of the 
resilient force of the compression springs 24 on right and left when the 
coils 2A, 2B, 2C are not energized. By applying direct current to the 
coils 2A, 2B, 2C, the magnet moving body 3 is driven to one side. When 
alternating current is applied to the coils, the magnet moving body 3 
functions as a vibrator by the reciprocating operation thereof. However, 
when having made a certain displacement, the magnet moving body 3 is made 
to return to the middle position by the resilient force of the compression 
springs 24. As a result, noise due to collision of the magnet moving body 
23 against the side plates 21C, 21D can be prevented. 
FIG. 29 shows an eleventh embodiment of the invention. In FIG. 29, 
nonmagnetic side plates 21A, 21B are fitted into and secured to both ends 
of a sleeve-like magnetic substance 1 and of a nonmagnetic guide sleeve 4. 
Annular permanent magnets 25 for returning the magnet moving body 3 are 
fixed on the inner circumferences of the projecting portions 23 of the 
side plates 21A, 21B. The through shaft body 8 of the magnet moving body 3 
passes through inner circumferential holes of the return annular permanent 
magnets 25 and the bearing members 22. The return annular permanent 
magnets 25 have, on the surfaces confronting the magnet moving body 3, 
magnetic poles that generate repulsive force relative to the magnetic 
poles on the outer ends of the permanent magnets 5A, 5B of the magnet 
moving body 3. In FIG. 29, e.g., the S-poles on the outer sides of the 
permanent magnets 5A, 5B confront the S-poles of the return annular 
permanent magnets 25. Other configurational aspects of the eleventh 
embodiment are the same as those of the ninth embodiment. 
According to the eleventh embodiment, the magnet moving body 3 is returned 
to the middle position in the sleeve-like magnetic substance 1 because of 
the resilient force of the return annular permanent magnets 25 on right 
and left when the coils 2A, 2B, 2C are not in conduction. By applying 
direct current to the coils 2A, 2B, 2C, the magnet moving body 3 can be 
driven to one side. When alternating current is applied to the coils, the 
magnet moving body 3 functions as a vibrator by the reciprocating 
operation thereof. However, when having made a certain displacement, the 
magnet moving body 3 is made to return to the middle position by the 
resilient force of the return annular permanent magnets 25. As a result, 
noise due to collision of the magnet moving body 3 against the side plates 
21A, 21B and the annular permanent magnets 25 can be prevented. 
FIG. 30 shows a twelfth embodiment of the invention. In FIG. 30, a magnet 
moving body 3 includes: two hollow cylindrical rare-earth permanent 
magnets 5A, 5B arranged with the same poles thereof confronting each 
other; a hollow cylindrical intermediate magnetic substance 6 interposed 
between these permanent magnets 5A, 5B; hollow disc-like outer end 
magnetic substances 26 arranged on the outer sides of the permanent 
magnets 5A, 5B; and hollow disc-like cushion plates 27A, 27B arranged on 
the outer sides of the outer end magnetic substances 26 with a through 
shaft body 8 made of a metal being inserted therethrough. The through 
shaft body 8 is held by causing clampers (E rings made of a metal) 20 to 
be fitted into fitting grooves 29 of the through shaft body 8, so that the 
permanent magnets 5A, 5B, the intermediate magnetic substance 6, the outer 
end magnetic substances 26, and the disc-like cushion plates 27A, 27B are 
fixed on the metallic through shaft body 8. The through shaft body 8 is 
made of either a nonmagnetic or magnetic metal. The cushion plates 27A, 
27B are made of an elastic material such as silicon rubber, and are 
interposed between a pair of fasteners 20 while compressed slightly. As a 
result, the cushion plates 27A, 27B can absorb variations in the thickness 
of the respective permanent magnets 5A, 5B and the magnetic substances 6, 
26, thereby preventing play of these components. An adhesive may 
additionally be used for integrating the metallic through shaft body 8 
with the permanent magnets 5A, 5B and the magnetic substance 6. The 
thickness of each outer end magnetic substance 26 is designed about half 
or same (50 to 100%) of the intermediate magnetic substance 6. Other 
configurational aspects of this embodiment are the same as those of the 
ninth embodiment. 
In the twelfth embodiment, since the outer end magnetic substances 26 are 
arranged on the outer end surfaces of the permanent magnets 5A, 5B of the 
magnet moving body 3, the magnetic flux radiated from the magnetic poles 
on the outer end surfaces of the permanent magnets 5A, 5B are easy to bend 
perpendicularly due to the presence of the outer end magnetic substances 
26. For this reason or the like, the vertical component of the magnetic 
flux density (the component perpendicular to the axial direction of the 
permanent magnets) in the outer side portion of the permanent magnets 5A, 
5B increases. That is, the magnetic flux density perpendicular to the 
longitudinal direction of the magnet moving body 3A which contributes to 
producing a thrust to be produced based on the Fieming's left hand rule 
can be increased. A still larger thrust can be produced by applying 
current to the three coils 2A, 2B, 2C wound annularly around the magnet 
moving body 3 so that a magnetic field of opposite polarity can be 
generated alternately. For example, an improvement in thrust by up to 10% 
or so can be obtained compared with the ninth embodiment involving no 
outer end magnetic substances. 
While the magnet moving body 3 formed of the two permanent magnets arranged 
with the same poles thereof confronting each other and the magnetic 
substance interposed therebetween has been exemplified in the ninth to 
eleventh embodiments, the magnet moving body may be formed of three or 
more permanent magnets with the same poles thereof confronting each other 
and magnetic substances interposed therebetween. In this case, the number 
of coils can be increased to four or more to match the increase in the 
number of permanent magnets. 
Further, while the magnet moving body 3 formed of the two permanent magnets 
arranged with the same poles thereof confronting each other, the 
intermediate soft magnetic substance interposed therebetween, and the 
outer end magnetic substances arranged on the outer sides of the two 
permanent magnets has been exemplified in the twelfth embodiment, the 
magnet moving body may be formed of three or more permanent magnets with 
the same poles thereof confronting each other and magnetic substances 
interposed therebetween. In this case, the number of coils can be 
increased to four or more to match the increase in the number of permanent 
magnets. In addition to the configuration of the twelfth embodiment, the 
compression springs 24 or the annular permanent magnets 25 for biasing the 
magnet moving body back to the middle position as described in the tenth 
and eleventh embodiments may, of course, be arranged. 
Still further, while both ends of the through shaft body of the magnet 
moving bodies 3, 3A are supported by the bearings in the ninth to twelfth 
embodiments, such a structure that only one side of the through shaft body 
may be supported by the bearing may be applicable. In this case, only one 
bearing is used (however, it is desirable to use a longer bearing member). 
As described above, in the first to twelfths embodiments of the present 
invention, while the magnet moving body formed of the two permanent 
magnets arranged with the same poles thereof confronting each other and 
the magnetic substance interposed therebetween has been exemplified, the 
magnet moving body may be formed of three or more permanent magnets with 
the same poles thereof confronting each other and magnetic substances 
interposed therebetween as shown in FIG. 31. In this case, the number of 
coils can be increased to four or more to match the increase in the number 
of permanent magnets. 
Still further, such a structure that the coils 2A, 2B, 2C are fixed on the 
inner circumferential side of the yoke 1 with insulation may also be 
adopted without the guide sleeve 4. 
Still further, while the sleeve-like yoke 1 and the guide sleeve 4 are used 
in the above-described embodiments, a square pillar-shaped yoke or guide 
sleeve may also be used. In this case, each coil may be wound around the 
outer circumference of the magnet moving body as in the other cases. 
As described in the foregoing pages, the moving magnet-type actuator of the 
invention is characterized as forming a magnet moving body by interposing 
a magnetic substance between at least two permanent magnets, the same 
poles of the permanent magnets confronting each other. As a result of the 
configuration, a magnetic flux component perpendicular to the longitudinal 
direction of the magnet moving body (the direction in which the permanent 
magnets are magnetized) can be sufficiently increased. In addition, since 
at least three coils are wound around the outer circumference of the 
magnet moving body so that the current in the coils can cut across the 
magnetic flux produced from the magnetic poles of the magnet moving body 
effectively, a thrust to be generated between the vertical magnetic flux 
component and the current flowing through the respective coils based on 
the Fieming's left hand rule can be increased to a sufficient degree. 
Consequently, the moving magnet-type actuator capable of providing a large 
thrust by a small structure and a small current can be achieved. 
Further, the moving magnet-type actuator of the device is characterized as 
forming a magnet moving body by interposing a magnetic substance between 
at least two permanent magnets with the same poles of the permanent 
magnets confronting each other, and by accommodating and fixing these 
components in a nonmagnetic sleeve-like holder. As a result of the 
configuration, the magnet moving body is made into a rigid structural body 
with improved wear resistance. 
Furthermore, the magnet moving body has a feature that the output 
extracting pin is arranged on one side thereof, so that the movement of 
the magnet moving body can be made smooth by supporting the pin with the 
bearing member that maintains a predetermined positional relationship with 
respect to the three coils. 
Still further, the moving magnet-type actuator of the invention is 
characterized as forming a magnet moving body by interposing an 
intermediate magnetic substance between at least two permanent magnets 
with the same poles of the permanent magnets confronting each other, and 
by arranging outer end magnetic substances on the outer end surfaces of 
the permanent magnets. This configuration contributes to sufficiently 
increasing a magnetic flux component perpendicular to the longitudinal 
direction of the magnet moving body (the direction in which the permanent 
magnets are magnetized), such component being derived not only from the 
portion at which the same poles of the permanent magnets confront each 
other, but also from the outer end portions of the permanent magnets. In 
addition, since at least three coils are formed around the outer 
circumference of the magnet moving body so that the current in the coils 
can cut across the magnetic flux produced from the magnetic poles of the 
magnet moving body effectively, a thrust to be generated between the 
vertical magnetic flux component and the current flowing through the 
respective coils based on the Fieming's left hand rule can be increased to 
a sufficient degree. Consequently, the moving magnet-type actuator capable 
of providing a large thrust by a small structure and a small current can 
be achieved. 
Furthermore, the moving magnet-type actuator of the device is characterized 
as forming a magnet moving body by interposing an intermediate magnetic 
substance between at least two permanent magnets and integrating these 
components with a through shaft body, the same poles of the two permanent 
magnets confronting each other and the through shaft body being supported 
slidably by bearing members. As a result of the configuration, a magnetic 
flux component perpendicular to the longitudinal direction of the magnet 
moving body (the direction in which the permanent magnets are magnetized) 
can be sufficiently increased. In addition, since at least three coils are 
wound around the outer circumference of the magnet moving body so that the 
current in the coils can cut across the magnetic flux produced from the 
magnetic poles of the magnet moving body effectively, a thrust to be 
generated between the vertical magnetic flux component and the current 
flowing through the respective coils based on the Fieming's left hand rule 
can be increased to a sufficient degree. Further, the use of the through 
shaft body allows a plurality of permanent magnets and intermediate 
magnetic substances to be fixed surely, thus making the magnet moving body 
rigid and facilitating the assembling work therefor. The use of the 
through shaft body also dispenses with a nonmagnetic holder or the like 
for covering the outer circumference of the permanent magnets and the 
intermediate magnetic substance for their integration, thereby 
contributing to a further improvement of thrust while decreasing the gap 
between the outer circumference of the permanent magnets and the 
respective coils. Still further, by supporting the through shaft body 
functioning as an output extracting pin of the magnet moving body with the 
bearing members that maintain a predetermined positional relationship with 
respect to the three coils, the magnet moving body can move smoothly. 
Consequently, a highly reliable moving magnet-type actuator that can 
produce a large thrust by a small structure and a small current can be 
achieved.