Electrical generator or motor structure – Dynamoelectric – Linear
Reexamination Certificate
1999-11-12
2001-07-24
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Linear
Reexamination Certificate
active
06265793
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
This invention relates to a coil with a level difference, suitably usable in a linear motor, for example, for moving an X-Y stage of a semiconductor exposure apparatus or a precision positioning stage of a precision machining apparatus, for example. In another aspect, the invention is concerned with a method of producing a coil with a level difference, such as described above. In further aspects, the invention is concerned with a linear motor, a stage system, an exposure apparatus or a device manufacturing method which uses such a coil with a level difference.
A linear motor to be used in driving an X-Y stage of a semiconductor exposure apparatus or a precision positioning stage of a precision machining apparatus, for example, has a structure such as shown in
FIG. 18A
or
18
B. As shown in the drawings, a workpiece
112
is placed on a stage
110
which is slidably supported on a guide
111
, fixedly mounted on a base (not shown), for sliding motion along a driving direction. The stage can be moved in the driving direction by means of a linear motor system
101
having components disposed on the opposite sides of the stage
110
. More specifically, the linear motor
101
has stators
102
each having six coils
105
fixedly mounted on a stator frame
104
to provide a stator unit. The stator frames
104
are disposed along the guide
111
and on the opposite sides thereof, and they are fixed to the unshown base through fixing members (not shown). Moving elements
103
of the linear motor
101
each comprises a four-pole magnet
106
which is magnetized vertically and combined integrally with a yoke
108
a
or
108
b
. There are upper and lower moving elements
103
disposed above and below the stator
102
unit, and the pairs of the moving elements
103
are fixedly mounted on the opposite sides of the stage
110
without contact to the stator
102
. The six coils
105
are arrayed along the driving direction of the stage
110
, with a pitch 1.5 times the magnetic pole pitch thereof. The magnetic pole pitch corresponds to a half period of a basic wave of the magnetic density. Therefore, the pitch of the six coils
105
corresponds to 0.75 period of the basic wave of the magnetic density, and, in terms of electric angle, it corresponds to 270 deg. or −90 deg.
In operation of the linear motor of the structure described above, while a relative positional relation between the magnet
106
and the coils
105
is detected by means of a sensor (not shown), those coils
105
at positions spaced by 270 or −90 degrees are sequentially selected and an electric current is applied sequentially to these coils in an appropriate direction, by which a driving force in the same direction is produced. In the sense that coils having orthogonal electric angles are sequentially interchanged, it is a dual-phase motor.
FIGS. 19A and 19B
show another type of linear motor In this linear motor
201
, upper and lower yokes
204
a
and
204
b
each comprising a laminated steel plate are disposed at a stator
202
side, and only magnets
206
are made movable for reduction of the weight of the whole moving parts. More specifically, there are four-pole magnets
206
which are fixedly mounted, through supporting members
207
, on opposite sides of a stage
110
being slidably movable along a guide
111
, by which movable elements
203
are provided. Upper and lower yokes
204
a
and
204
b
have a plurality of arrayed flat coils
205
, by which stators
202
are provided. The flat coils
205
and the yokes
204
a
and
204
b
are fixedly mounted along the opposite sides of the guide
111
, so as to sandwich the movable element
203
between them with respect to a vertical direction. The function and operation of this linear motor are the same as those of the structure shown in
FIGS. 18A and 18B
.
In the linear motors shown in
FIGS. 18A
,
18
B,
19
A and
19
B, only a half area of the magnet faces to the coil and, therefore, it is difficult to accomplish an efficient ampere-turn per magnet area. As a solution for the problem of ampere-turn, structures such as shown in
FIGS. 20A
,
20
B,
22
A and
22
B have been proposed, wherein coils are disposed with partial overlapping.
In the coil structure of a linear motor shown in
FIGS. 20A and 20B
, which is also illustrated in an enlarged view of
FIG. 21
, a phase-A coil
305
a
and a phase-B coil
305
b
are disposed with a shift of 90 deg. with reference to a length twice the magnetic pitch, such that they partially overlap with each other. If a phase-A coil and a phase-B coil are simply placed with overlapping, the air gap of the magnet increases by an amount corresponding to the coil thickness. In consideration of it, the magnet faces m of straight portions of the phase-B coil
305
b
to be opposed to the magnet are bent down so that they become coplanar with the phase-A coil
305
a.
In order to produce a coil with a level difference (step) such as the phase-B coil
305
b
described above, a wire c may be wound around a core (not shown) by a predetermined number of turns, to form a simple flat coil similar to the phase-A coil
305
a
. Here, the wire c may not be bonded, but temporarily fixed, so as to keep the shape as a whole. Subsequently, the flat coil may be bent mechanically to make a level difference (step). Then, the wire c may be bonded, whereby a coil with a level difference may be accomplished. In regard to a coil of a large thickness such as the coil
105
shown in
FIG. 18A
or ISE, a phase-B coil with a level difference cannot be produced. On that occasion, a phase-A coil
305
a
of a thickness about a half of that of the coil shown in
FIG. 18A
or
18
B and a phases coil
305
b
with a level difference may be prepared, and they may be disposed with a shift of 90 deg., as shown in
FIG. 21
, to provide a unit coil
305
u.
In the linear motor structure
301
shown in
FIG. 20A
or
20
B, only the magnet is a movable element. There are unit coils
305
u
juxtaposed to the laminated yoke
304
(
304
a
and
304
b
), by which a stator unit
302
is provided. The stator units
302
are fixedly supported by supporting means (not shown), from above and below the magnet
306
. With the division of the stator into two, upper and lower stator elements as described above, an efficient total coil thickness may be attained.
On the other hand, in the linear motor structure
401
shown in
FIGS. 22A and 22B
, coplanar faces of unit coils
305
u
such as described above are adhered to each other to provide a double-coil unit
305
w
. Such double-coil units
305
w
are juxtaposed with each other along the driving direction, and they are fixed together by fixing means (not shown) corresponding to the stator frame of
FIG. 18A
, by which a stator
402
is provided. Movable elements
403
have a similar structure as that shown in
FIG. 18A
or
18
B. Here, upper and lower yokes
408
a
and
408
b
having four-pole magnets
406
are coupled to each other through side plates
409
a
and
409
b
so that their magnets are opposed to each other, by which a box-like movable element
403
is provided. Also, in this example, a coil with a level difference having a large thickness cannot be produced at once. Thus, small-thickness unit coils
305
u
are adhered to each other to provide a double-coil unit
305
w
, by which an efficient total coil thickness is accomplished.
As regards the production of a coil with a level difference, to be used in a linear motor, for example, the coil-bending method described above needs the procedure for winding a wire to form a coil, bending the coil not. bonded, and then bonding the wire. Thus, the coil production process is very complicated.
Further, the coil bending work applies a stress to the wire, causing decreased insulation reliability or a possibility of breakage of the wire.
Moreover, it is difficult to bend a thick coil. If, therefore, a thick coil is desired, it is necessary to prepare thin coils and to couple them together after bending them separately. The number of co
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Jones Judson H.
Ramirez Nestor
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