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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a linear electromagnetic actuator commonly
used for moving an object to be moved with high accuracy in, for example,
a motion mechanism such as a machine tool or industrial robot, and to a
drive unit in which a guiding means for guiding an object is added to said
linear electromagnetic actuator.
2. Description of the Prior Art
FIG. 1 shows an example of this type of drive unit of the prior art.
As shown in the drawing, said drive unit has a guiding device in the form
of two track rails 2 fixed in parallel on base 1 in which tracks are
formed along the respective lengthwise direction, and a slider 4
juxtapositioned over said track rails 2 and guided by said tracks. In
addition, a linear electromagnetic actuator in the form of a linear pulse
motor is used. Mutually coupled permanent magnets and electromagnets are
composed on its primary side (not shown) and attached to the lower surface
of the above-mentioned slider 4. The secondary side is composed of a
rectangular plate-shaped member in which a plurality of inductor teeth
(reference numeral not shown) having high magnetic permeability are formed
to as to be arranged in the direction of the tracks. These inductor teeth
and the above-mentioned electromagnet are made to be in opposition.
On the other hand, a detection device for detecting the relative positions
of the above-mentioned primary side and secondary side is provided, and
said detection device is composed in the manner described below.
Furthermore, in the case of this example of the prior art, the secondary
side 6 is stationary, while the primary side moves in the form of the
moving side.
As shown in the drawing, said detection device has a detected portion in
the form of linear magnetic scale 8 provided on base 1 so as to extend in
the direction of movement of slider 4 attached to the above-mentioned
primary side, and a detecting portion in the form of an electromagnetic
conversion element (not shown) attached to the lower surface of slider 4
so as to correspond with said linear magnetic scale 8. Differing magnetic
poles (N and S) are alternately and precisely arranged and magnetized in
the lengthwise direction on said linear magnetic scale 8, and signals are
generated corresponding to each of said magnetic poles from the
above-mentioned electromagnetic conversion element that moves along said
linear magnetic scale 8 together with slider 4, thus enabling slider 4,
namely the position of the above-mentioned primary side, to be detected
based on these signals.
Furthermore, in FIG. 1, reference numeral 9 indicates a cable guide that
houses a connection cable (not shown) for supplying an electrical source
to the electromagnet included in the above-mentioned primary side and
transmitting signals emitted from the above-mentioned electromagnetic
conversion element to the outside. As shown in the drawing, this cable
guide 9 is composed by mutually linking a large number of links in series
so as to be driven by pivoting freely, and acts to maintain said
connection cable in a prescribed curved shape as well as protect the
connection cable from being damaged even during movement of slider 4.
In the drive unit of the prior art described above, the durability of the
above-mentioned connection cable (not shown) provided so as to transmit
signals and so forth cannot always be said to be favorable due to the
relatively large inertial force produced due to its own weight being
applied whenever the drive unit is operated. Consequently, there is the
risk of disconnection in the case of use over an extended period of time
or when the operating frequency of slider 4 is high.
In addition, since the weight of the above-mentioned connection cable
itself is somewhat large, and the weight relating to wiring is also large
as a result of combining the above-mentioned cable guide 9, this weight
produces resistance to the operation of the above-mentioned slider 4, thus
resulting in the disadvantage of being unable to obtain high-precision
operation.
In addition, since cable guide 9 having the above-mentioned constitution is
considerably expensive, this results in another problem to be solved in
terms of attempting to reduce the cost of the apparatus.
Moreover, since cable guide 9 occupies a large space, this becomes an
obstacle to attempting to reduce the size of the apparatus.
SUMMARY OF THE INVENTION
In consideration of the above-mentioned disadvantages of the prior art, the
object of the present invention is to provide a linear electromagnetic
actuator and drive unit wherein the wiring for signal transmission and so
forth is ensured to have high durability and the resistance produced by
the wiring that has an effect on the operation of the moving portion is
made to be as small as possible to allow the obtaining of a highly
accurate operating state, while also achieving low cost and compact size.
In addition to these objects, another object of the present invention is
to maintain the function of the wiring itself for a long time.
The linear electromagnetic actuator according to the present invention has
a flexible printed wiring substrate that transmits signals and so forth
juxtapositioned in a bent state between primary and secondary sides that
mutually perform relative movement, and is provided with a sliding member
that can slide with respect to said printed wiring substrate between both
ends of said printed wiring substrate, and has a small coefficient of
friction so as to extend along the direction of said relative movement.
In addition, the drive unit according to the present invention is equipped
with a linear electromagnetic actuator and a guiding device that guides
the relative movement of the primary and secondary sides of said linear
electromagnetic actuator, has a flexible printed wiring substrate that
transmits signals and so forth juxtapositioned in a bent state between
said primary and secondary sides, and is provided with a sliding member
that can slide with respect to said printed wiring substrate between both
ends of said printed wiring substrate, and has a small coefficient of
friction so as to extend along the direction of said relative movement.
In said constitution, as a result of guiding of a printed wiring substrate
being performed by a sliding member, when the printed wiring substrate
follows the movement of the moving portion of the linear electromagnetic
actuator or drive unit accompanying its movement, deflection into large or
complex shapes is prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the essential portion of a drive unit of
the prior art.
FIG. 2 is a perspective view, including a partial cross-section, of a drive
unit as an embodiment of the present invention.
FIG. 3 is an overhead view of the drive unit shown in FIG. 2.
FIG. 4 is a view, including a partial cross-section, taken along arrows
I--I relating to FIG. 3.
FIG. 5 is a perspective view, including a partial cross-section, of a track
rail and slide member equipped on the drive unit shown in FIGS. 2 through
4.
FIG. 6 is an exploded perspective view, including a partial cross-section,
of the essential portion of a linear direct current motor contained in the
drive unit shown in FIGS. 2 through 4.
FIG. 7 is a perspective view of a field magnet that is a constituent member
of the secondary side of the linear direct current motor contained in the
drive unit shown in FIGS. 2 through 4.
FIG. 8 is a perspective view of the essential portion of the drive unit
shown in FIGS. 2 through 4.
FIG. 9 is a side view for explaining the operation of the essential portion
of the drive unit shown in FIGS. 2 through 4.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following provides an explanation of a drive unit as an embodiment of
the present invention with reference to the attached drawings.
Furthermore, said drive unit is composed by mutually adding a linear
electromagnetic actuator in the form of a linear direct current motor and
a guiding device that together with holding an object to be moved, guides
the mutual operation of the primary and secondary sides of said linear
direct current motor. In the case of the present embodiment, although a
moving magnet type of linear direct current motor is employed for the
linear electromagnetic actuator, various other types of linear
electromagnetic actuators can naturally also be applied, examples of which
include a moving coil type of linear direct current motor, linear pulse
motor and voice coil motor.
First, an explanation is provided of the above-mentioned guiding device.
As shown in FIGS. 2 through 4, this guiding device has bed 21 formed
roughly into the overall shape of a flat plate and table 22 to move along
the lengthwise direction of said bed 21. As shown in FIGS. 2 and 4, coil
yoke 23, formed into the shape of a flat plate and having nearly the same
length as bed 21, is arranged on the upper surface of bed 21, and is
fastened to said bed 21 by a plurality of bolts (with hexagon sockets, see
FIG. 4) 25.
Two track rails 27 are arranged on both sides of the upper surface of said
coil yoke 23 along the lengthwise direction of said coil yoke 23, and are
fastened to said coil yoke 23 by a plurality of countersunk head screws 28
(see FIG. 4).
As shown in FIG. 5, a track in the form of a single track groove 27a,
having a roughly semi-circular shaped cross-section, is formed in the
outside of the above-mentioned track rail 27. As is clear from FIGS. 2 and
4, a slider in the form of slide member 30, able to freely perform
relative motion with respect to said track rail 27, is arranged on the
outside of said track rail 27, and is fastened to the lower surface of
table 22 by, for example, two bolts (with hexagon sockets) 32.
Furthermore, as is clear from FIG. 4, countersunk portions 22a and
insertion holes 22b are formed in table 22 into which the head portions
and threaded portions, respectively, of bolts 32 are inserted. Bolts 32
are embedded in these countersunk portions 22a and insertion holes 22b,
and do not protrude from the upper surface of table 22.
A rolling element circulating path (not shown) is formed in the
above-mentioned slide member 30, and rolling elements in the form of a
large number of balls 33 are arranged and contained within said rolling
element circulating path. These balls 33 bear the load between track rail
27 and slide member 30 by circulating while rolling over track groove 27a
of track rail 27 accompanying movement of slide member 30 with respect to
track rail 27.
As shown in FIG. 5, the above-mentioned slide member 30 has casing 34, a
pair of end caps 36a and 36b coupled to both ends of said casing 34 by
countersunk head screws 35, and two seals 37a and 37b fastened to the
outer surfaces of both of said end caps 36a and 36b. The above-mentioned
rolling element circulating path is composed of a load bearing track
groove and return path formed mutually in parallel and passing linearly
through casing 34 in the lengthwise direction of said casing 34, and a
pair of roughly arc-shaped direction changing paths formed in both end
caps 36a and 36b that connect both ends of said load bearing track groove
and return path. Furthermore, said load bearing track groove opposes track
groove 27a of track rail 27.
The guiding device of the constitution described above is fastened to a
flat mounting surface equipped on, for example, a machine tool (not shown)
by a plurality of bolts (with hexagon sockets: not shown). Consequently,
as shown in FIG. 4, bed 21 has flat mounting bottom surface 21a for
anchoring said bed 21 to said mounting surface. As shown in FIGS. 2
through 4, countersunk portions 21b and insertion holes 21c are formed in
both sides of bed 21 into which the head portions and threaded portions of
the above-mentioned bolts for fastening said bed are respectively
inserted. Said bolts are embedded in these countersunk portions 21b and
insertion holes 21c, and do not protrude from the upper surface of bed 21.
In addition, as shown in FIGS. 2 and 3, for example, four threaded holes
22c are formed in the four corners of the upper surface of table 22 able
to move with respect to this bed 21, and a table (not shown) equipped on
an apparatus, such as a machine tool, on which said drive unit is equipped
is fastened to said table 22 by bolts (not shown) screwed into these
threaded holes 22c.
Continuing, the following provides a detailed description of the primary
and secondary sides of the direct current linear motor that composes the
drive unit by being mutually added to a guiding device having the
constitution described above.
To begin with, as shown in FIGS. 2 through 4 and 6, the primary side has
the previously described coil yoke 23 installed on bed 21, coil substrate
40 arranged along the lengthwise direction of said coil yoke on the upper
surface of said coil yoke 23, and, for example, 14 armature coils 42
supported by being affixed in a row along the direction in which the
above-mentioned table 22 is to move over the lower surface of said coil
substrate 40, namely the side of coil yoke 23. Furthermore, each armature
coil 42 is wound into roughly the shape of a rectangular loop. In
addition, as shown in FIGS. 4 and 6, Hall effect elements 63 are provided
corresponding to each armature coil 42 on coil substrate 40.
Each of the above-mentioned armature coils 42 and coil substrate 40 are
fastened together to coil yoke 23 with said coil substrate 40 to be
outside by fastening members in the form of countersunk head screws 44,
for example, two each of which are inserted for each of said armature
coils 42.
As shown in FIGS. 4 and 6, spacer assemblies 46 are juxtaposed between coil
substrate 40 fastened by countersunk head screws 44 and coil yoke 23 into
which said countersunk head screws 44 are screwed. These spacer assemblies
46 are provided so that deformation, such as warping and so forth, does
not occur in coil substrate 40 caused by tightening of countersunk head
screws 44, and are fit inside each armature coil 42.
Next, the following provides an explanation of the circuit substrate for
performing supply of electricity and so forth to each of the
above-mentioned armature coils 42.
As shown in FIGS. 2, 4 and 6, circuit substrate 50 is arranged in parallel
with coil substrate 40 on the lower surface of bed 21 on which said coil
substrate 40 is installed on its upper surface with coil yoke 23 in
between. Moreover, said circuit substrate 50 is fastened to bed 21 by a
plurality of bolts (with hexagon sockets) 25. Furthermore, these bolts 25
also serve to fasten the above-mentioned coil yoke 23 to bed 21.
As shown in FIG. 6, the above-mentioned circuit substrate 50 is composed of
a plurality of separate portions 55 joined together, each provided with a
drive circuit composed of electronic components 53, 54 and so forth. These
separate portions 55 are provided corresponding to each unit of two
armature coils each of the fourteen armature coils 42 provided in a row.
Thus, the number of these separate portions 55, in this case, is seven.
The drive circuit provided on each of the above-mentioned separate portions
55 contains one set of circuit portions supplying excitation current to
one armature coil 42, or in other words, a circuit corresponding to two
armature coils 42.
Continuing, the following provides a detailed description of the separate
constitution of the above-mentioned circuit substrate 50 and coil
substrate 40 arranged above it.
To begin with, the following provides an explanation of circuit substrate
50.
In the case of fabricating this circuit substrate 50, a base substrate K
74, having a base length, is made available (a portion of which is shown
in FIG. 6). This base substrate K 74 is composed of, for example, six
separate portions 55, explained based on FIG. 6, joined into a single
unit. As was previously described, these separate portions 55 are provided
with a drive circuit that performs supply of electricity and so forth to
two armature coils, two of each of which are grouped into individual
units. Furthermore, as is shown in FIG. 6, marks in the form of broken
lines 75 are printed on both the top and bottom surfaces of base substrate
K 74 (only the bottom surface is shown in the drawing) for distinguishing
each separate portion 55.
Since the previously described circuit substrate 50 must link together
seven of the above-mentioned separate portions 55, said circuit substrate
50 is completed by severing one of the six separate portions 55 possessed
by the above-mentioned base substrate K 74 along broken line 75 to
separate, arranging this separated separate portion 55 in a row at one end
of unseparated base substrate K 74 as shown in FIG. 6, and mutually
connecting their corresponding connection terminals.
Furthermore, in FIG. 6, connection between the above-mentioned separate
portions 55 and base substrate K 74 is performed by a single connection
component 77 having terminals 77a fit into through holes 55b provided at
the portion of both connection terminals 55a. Furthermore, although
connection between corresponding connection terminals 55a may be performed
using copper wire and so forth, by performing connection using these
connection components, in addition to connection of connection terminals
55a being able to be performed all at once, connections are reinforced due
to the rigidity of said connection components 77. Moreover, in addition to
using components that simply act to make electrical connections,
electronic components such as IC and so forth may also be used for
connection components 77.
The following provides an explanation of coil substrate 40.
Although the overall coil substrate 40 is not shown, in the case of
fabricating this coil substrate 40, a base substrate C 79 of a length
nearly equal to base substrate K 74 for the above-mentioned circuit
substrate 50 is made available as shown in FIG. 6. This base substrate C
79 is composed by linking together six separate portions 80 into a single
unit in the same manner as base substrate K 74 for circuit substrate 50.
As shown in the drawing, two armature coils 42 each are affixed, grouped
together in units, on these six separate portions 80, thus making the
total number of armature coils 42 arranged in a row on base substrate C 79
twelve. Furthermore, as shown in FIGS. 6 and 3, marks in the form of
broken lines 81 are printed on the top and bottom surfaces of base
substrate C 79 to distinguish these separate portions 80. As shown in FIG.
6, circuit substrate 50 is formed by joining and connecting a single
separate portion 80 separated from another base substrate not shown to one
end of this unseparated base substrate C 79. Furthermore, in FIG. 6,
reference numeral 80a indicates connection terminals provided on each
separate portion 80.
Furthermore, in the description thus far, although two armature coils 42
each and a drive circuit for driving said armature coils 42 are separated
into units with respect to coil substrate 40 and circuit substrate 50,
three or more armature coils 42 and their drive circuit may also be
separated into their respective units. In addition, although base
substrate C 79, which supports twelve armature coils 42, and base
substrate K 74, on which a plurality of drive circuits are arranged in a
row corresponding to two of these armature coils 42 each, are made
available during fabrication of the drive unit equipped with a total of
fourteen armature coils 42 in the present embodiment, it is only natural
that the setting of the total length of these base substrates K 74 and C
79, namely the number of armature coils and drive circuits to be equipped
on these, can be suitably changed.
In addition, although coil substrate 40 and circuit substrate 50 are
composed by separating at least one of separate portions 55 and 80
provided on base substrate K 74 and C 79, and joining it to unseparated
base substrates K 74 and C 79 in the present embodiment, in the case the
operating stroke of the drive unit to be fabricated is shorter than the
total length of base substrates K 74 and C 79, at least one of each of
separate portions 55 and 80 provided on each of said base substrates K 74
and C 79 should be cut away as necessary. In this manner, a substrate of
desired length can be easily obtained simply by cutting away a portion
from a base substrate and adding to another unseparated base portion or
simply cutting away a portion of a base substrate. In addition, the
remaining portion of the base substrate from which a portion was cut away
as described above can be used for other applications irrespective of its
state.
As shown in FIGS. 4 and 6, coil substrate 40 and circuit substrate 50,
which are arranged to be mutually separated by bed 21 and coil yoke 23,
are connected by connecting a plurality, in this case seven, of connection
devices in the form of both corresponding male and female connectors 83
and 84 provided on mutually opposing sides of both said substrates. One
each of these connectors 83 and 84 are arranged with respect to each
separate portion 55 and 80 each provided with two armature coils 42 each
and their drive circuit grouped into a unit as previously described. As
shown in FIG. 4, said connectors 83 and 84 are mutually connected through
apertures 21e and 23e formed in bed 21 and coil yoke 23. Thus, since one
each of connectors 83 and 84 is provided for each of separate portions 55
and 80 of coil substrate 40 and circuit substrate 50, when mutually
assembling both said separate portions 55 and 80, the directions of both
can be recognized both quickly and easily, thus facilitating assembly
work. Furthermore, connection of corresponding separate portions 55 and 80
may be performed by lead wires and not by connectors as described above.
In addition, with respect to the number of connectors, besides providing
only one connector for each of separate portions 55 and 80 as mentioned
above, two or more connectors may also be provided.
On the other hand, the secondary side of the linear direct current motor is
composed in the manner described below.
As shown in FIGS. 2 and 4, said secondary side has magnet yoke 88, mounted
on the lower surface of table 22, and field magnet 89 anchored on the
lower surface of said magnet yoke 88 to oppose each of the above-mentioned
armature coils 42 of the primary side. As shown in FIG. 7, the overall
shape of field magnet 89 is formed into roughly that of a rectangular
plate, and a plurality of N and S magnetic poles, for example 5, are
magnetized so as to be alternately arranged in a row along direction A in
which relative movement is performed by the primary and secondary sides,
namely the lengthwise direction of bed 21.
In said drive unit, a detection device having the constitution described
below is provided for detecting the relative positions of the
above-mentioned primary and secondary sides, namely the relative positions
of the above-mentioned bed 21 and table 22.
Namely, said detection device is composed of a detected portion in the form
of linear magnetic scale 91 shown in FIGS. 2 through 4, and detecting
portion 92 shown in FIG. 4. Said linear magnetic scale 91 extends in the
direction of movement of the above-mentioned table 22, a large number of N
and S magnetic poles are alternately magnetized at a precise pitch along
its lengthwise direction, and an origin signal magnetized portion is
formed on one end. Together with being provided with a magnetic resistance
element (MR element, not shown) for origin detection, two magnetic
conversion elements (not shown) consisting of two Hall effect elements for
the A and B phases are arranged mutually shifted by 1/2 the
above-mentioned pitch. As a result of employing said constitution, both A
phase and B phase signals are obtained, thereby enabling detection of
relative position and discrimination of direction of movement. As shown in
FIGS. 2 through 4, said detection device is also provided with a flexible
printed wiring substrate 94 for transmitting signals emitted from the
above-mentioned detecting portion 92, and cover 95 for covering said
printed wiring substrate 94.
In the drive unit having the above-mentioned constitution, by supplying a
prescribed current to armature coils 42, thrust is produced based on
Fleming's right hand rule between the primary and secondary sides. For
example, if bed 21, to which the primary side is coupled, is taken to be
the stationary side, table 22, integrated into a single unit with the
secondary side, is moved by this thrust. Moreover, the position of table
22 with respect to bed 21 is detected by the detection device described
above.
The following provides a detailed description of the constitution of the
above-mentioned printed wiring substrate 94 and its periphery.
First, as was previously described, the following effects are obtained as a
result of employing flexible printed wiring substrate 94 for the wiring of
signal transmission and so forth.
Namely, since printed wiring substrate 94 is extremely lightweight, the
amount of inertial force produced in said printed wiring substrate 94
based on the operation of the moving portion of a linear electromagnetic
actuator (a linear direct current motor in the case of the present
embodiment) or drive unit (this moving portion refers to the secondary
side with respect to a linear direct current motor and to combination of
slide member 30 and table 22 coupled to the said secondary side with
respect to the drive unit) is small. In addition, since said printed
wiring substrate itself is tough, it also has excellent durability. Thus,
there is no risk of disconnection even when used at a high operation
frequency or over an extended period of time.
In addition, since printed wiring substrate 94 is extremely lightweight as
described above, the amount of resistance that acts on the operation of a
linear electromagnetic actuator or drive unit is small, thus enabling the
obtaining of a highly precise operating state.
Moreover, since printed wiring substrate 94 is relatively inexpensive,
reduced cost of the apparatus is achieved.
In addition, since printed wiring substrate 94 is thin and only occupies a
small amount of space, it facilitates reducing the size of the apparatus.
Next, an explanation is provided of the constitution provided to protect
the above-mentioned printed wiring substrate 94 and so forth.
As was previously described, printed wiring substrate 94 is for
transmitting signals by being juxtaposed in a bent state between the
primary and secondary sides of a linear direct current motor. More
specifically, as is shown in FIGS. 2, 4, 8 and 9, one end of printed
wiring substrate 94 is connected via socket 102 to the leading end of
substrate 101 anchored so as to protrude to the side on table 22 coupled
to said secondary side. The other end is connected via socket 104 to the
leading end of substrate 103 provided so as to protrude to the side on the
stationary side in the form of bed 21 coupled to the above-mentioned
primary side. Printed wiring substrate 94 is arranged so that the primary
surface of the portion other than bent portion 94a, namely the primary
surfaces of upper side 94b and lower side 94c positioned on both sides of
said bent portion 94a, is roughly perpendicular to the vertical direction,
namely the direction of gravity. In said constitution, printed wiring
substrate 94 follows the secondary side accompanying movement of said
secondary side with respect to the above-mentioned primary side.
Furthermore, although obvious, the position of bent portion 94a of printed
wiring substrate 94 changes accompanying movement of said secondary side,
while the lengths of upper side 94b and lower side 94c also change.
As shown in FIGS. 2, 4, 8 and 9, film-shaped sliding member 107 is provided
so as to be positioned between the upper and lower ends of the
above-mentioned printed wiring substrate 94. Moreover, said sliding member
107 is adhered to the upper side of bracket 108, having an L-shaped
cross-section, attached to the side of bed 21. More specifically, said
sliding member 107 is formed into a rectangular shape as shown in the
drawings, and is arranged so as to be able to slide with respect to
printed wiring substrate 94 while also extending along the direction of
movement of the above-mentioned secondary side. This sliding member 107 is
formed into the form of a film from a material having a small coefficient
of friction, an example of which is Teflon (TFET). Its thickness is set,
for example, from 0.05 mm to 0.13 mm. Said sliding member 107 is adhered
to the above-mentioned bracket 108 by using an adhesive (not shown) such
as a silicone adhesive. The thickness of this adhesive layer is set, for
example, from 0.03 mm to 0.05 mm.
Furthermore, in addition to using only Teflon (TFET) for the material of
sliding member 107, a compound material may also be used in which a woven
fabric consisting of fibers from a prescribed material are used as the
core material and Teflon is coated around said core material. In addition,
it is preferable that Teflon also be used for the material with respect to
said fibers themselves.
As has been described above, the following effects are obtained as a result
of employing printed wiring substrate 94 for the wiring for signal
transmission.
Namely, since printed wiring substrate 94 is extremely lightweight, the
amount of inertial force produced in said printed wiring substrate 94
based on the operation of the moving portion of a linear electromagnetic
actuator or drive unit is small. In addition, since said printed wiring
substrate itself is tough, it also has excellent durability. Thus, there
is no risk of disconnection even when used at a high operation frequency
or over an extended period of time.
In addition, since printed wiring substrate 94 is extremely lightweight as
described above, the amount of resistance that acts on the operation of a
linear electromagnetic actuator or drive unit is small, thus enabling the
obtaining of a highly precise operating state.
Moreover, since printed wiring substrate 94 is relatively inexpensive,
reduced cost of the apparatus is achieved.
In addition, since printed wiring substrate 94 is thin and only occupies a
small amount of space, it facilitates reducing the size of the apparatus.
As was previously described, in said drive unit, sliding member 107 having
a small coefficient of friction is juxtaposed between both ends of the
above-mentioned printed wiring substrate 94 provided in a bent state, and
said sliding member 107 is able to slide with respect to said printed
wiring substrate 94. Moreover, said sliding member 107 is arranged to as
to extend along the direction of relative movement of the primary and
secondary sides equipped on a linear electromagnetic actuator. Namely,
although this means that said printed wiring substrate 94 follows the
relative movement of said primary and secondary sides, said sliding member
107 is juxtaposed between the upper and lower sides 94b and 94c located on
both sides of bent portion 94a of printed wiring substrate 94.
According to said constitution, since said sliding member 107 demonstrates
the action of guiding printed wiring substrate 94, printed wiring
substrate 94, and in this case its upper side 94b, is in the state
indicated by the solid line and double dot broken line in FIG. 9. Thus,
said printed wiring substrate 94 is not deflected into a form that is
useless or complex. For this reason, contact by said upper side 94b with
peripheral members, and specifically cover 95, as well as contact by lower
side 94c is avoided. Thus, together with shorting and so forth being
avoided based on wearing down of the substrate surface layer that is a
cause of concern due to frequent repetition of contact over a long period
of time, application of excessive force to printed wiring substrate 94 is
prevented, thus enabling its function to be maintained for a long time.
Incidentally, in the case the above-mentioned sliding member 107 is not
provided, upper side 94b of printed wiring substrate 94 is greatly
deflected as shown by the single dot broken line in FIG. 9, thus resulting
in the risk of movement while making contact with cover 95.
Furthermore, although bottom side 94c of printed wiring substrate 94 makes
contact with cover 95 as shown with the double dot broken line in FIG. 9,
lower side 94c merely rides onto said cover 95 and does not move while
sliding over it, thus not resulting in a problem.
The above-mentioned effect is particularly remarkable in the case the
portions other than the bent portion of printed wiring substrate 94,
namely the primary surfaces of the above-mentioned upper side 94b and
lower side 94c, are arranged so as to be roughly perpendicular to the
vertical direction as in the present embodiment. Namely, this is because,
in the case printed wiring substrate 94 is arranged in this manner, since
the direction in which deflection occurs in both said sides 94b and 94c is
the direction of gravity, deflection is assisted by gravity.
In addition, in the linear electromagnetic actuator in the form of a linear
direct current motor equipped on said drive unit, a detection device is
provided that detects the relative positions of its primary and secondary
sides. Said detection device has a detected portion in the form of a
linear magnetic scale 91 attached to one side of either said primary or
secondary sides, and in this case the primary side, and a detecting
portion 92 that emits signals after detecting said detected portion that
is attached to the other side with respect to said one side, and namely to
the secondary side in this case. The above-mentioned printed wiring
substrate 94 is provided to transmit signals emitted from said detecting
portion 92. Namely, in the constitution of this type of detection device,
magnetic sensors, such as electromagnetic conversion elements, or optical
sensors are used for said detecting portion 92, and the above-mentioned
signals are obtained in the form of weak current. Thus, said constitution
is ideal as a result of using printed wiring substrate 94 which is not
suited for transmission of large current.
However, the above-mentioned printed wiring substrate 94 is not limited to
transmission of weak current in the form of the above-mentioned signals,
but rather may also be used to transmit relatively large current that can
be used for lighting lamps or driving objects.
Furthermore, although a guiding device having a mechanical constitution is
shown for the guiding device that performs mutual guiding of the primary
side and secondary side in the above-mentioned embodiment, a guiding
device can be employed having a constitution that relatively levitates
both primary and secondary sides by the pressure of a fluid (air or oil)
or magnetic force.
Moreover, the present invention may be applied similarly in the form of
another embodiment in the case of bed 21 and so forth having a certain
curvature, and the present invention performing curved motion.
According to the present invention as has been explained above, the
following advantages are offered as a result of employing a flexible
printed wiring substrate as the wiring for signal transmission and so
forth.
Namely, since the printed wiring substrate is extremely lightweight, the
amount of inertial force produced in said printed wiring substrate 94
based on the operation of the moving portion of a linear electromagnetic
actuator or drive unit is small. In addition, since said printed wiring
substrate itself is tough, it also has excellent durability. Thus, there
is no risk of disconnection even when used at a high operation frequency
or over an extended period of time.
In addition, since the printed wiring substrate is extremely lightweight as
described above, the amount of resistance that acts on the operation of a
linear electromagnetic actuator or drive unit is small, thus enabling the
obtaining of a highly precise operating state.
Moreover, since the printed wiring substrate is relatively inexpensive,
reduced cost of the apparatus is achieved.
In addition, since the printed wiring substrate is thin and only occupies a
small amount of space, it facilitates reducing the size of the apparatus.
In addition, in the present invention, a sliding member having a small
coefficient of friction is juxtaposed between both ends of the
above-mentioned printed wiring substrate provided in a bent state, and
said sliding member is able to slide with respect to said printed wiring
substrate. Moreover, said sliding member is arranged to as to extend along
the direction of relative movement of the primary and secondary sides
equipped on a linear electromagnetic actuator. Namely, although this means
that said printed wiring substrate follows the relative movement of said
primary and secondary sides, said sliding member is juxtaposed between two
sides located on both sides of the bent portion of the printed wiring
substrate. According to said constitution, since said sliding member
demonstrates the action of guiding the printed wiring substrate, the
printed wiring substrate is not deflected into a form that is useless or
complex. For this reason, contact by the printed wiring substrate with
peripheral members as well as between corresponding portions of the
printed wiring substrate itself are avoided. Thus, together with shorting
and so forth being avoided based on wearing down of the substrate surface
layer that is a cause of concern due to frequent repetition of contact
over a long period of time, application of excessive force to the printed
wiring substrate 94 is also prevented, thus enabling its function to be
maintained for a long time.
The above-mentioned effect is particularly remarkable in the case the
portions other than the bent portion of the printed wiring substrate,
namely the primary surfaces of the above-mentioned upper and lower sides,
are arranged so as to be roughly perpendicular to the vertical direction.
Namely, this is because, in the case the printed wiring substrate is
arranged in this manner, since the direction in which deflection occurs in
both of said sides is the direction of gravity, deflection is assisted by
gravity.
In addition, in the linear electromagnetic actuator according to the
present invention, a detection device is provided that detects the
relative positions of its primary and secondary sides. Said detection
device has a detected portion attached to one side of either said primary
or secondary sides, and a detecting portion that emits signals after
detecting said detected portion that is attached to the other side with
respect to said one side. The above-mentioned printed wiring substrate is
provided to transmit signals emitted from said detecting portion. Namely,
in the constitution of this type of detection device, magnetic sensors,
such as electromagnetic conversion elements, or optical sensors are used
for said detecting portion, and the above-mentioned signals are obtained
in the form of weak current. Thus, the present invention is ideal as a
result of using a printed wiring substrate which is not suited for
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