JPH06207945A - Electromagnetic driver, and speed sensor and linear voice coil motor used in this - Google Patents

Abstract

PURPOSE:To reduce leakage flux generated in a yoke and to lighten the yoke without reducing magnetic characteristics. CONSTITUTION:By inversely opposing and fixing a first yoke member 14a to a second yoke member 14b respectively having fronts of about L-shape, a yoke structure 14 of rectangular ring shape consisting of a front yoke 18. back yoke 19 and two side yokes 20 is constituted, two permanent magnets 5 are fixed inside, a sensor coil is movably inserted in the back yoke 19, and a speed sensor 3 is formed. By inversely opposing and fixing a first yoke member 17a to a second yoke member 17b respectively having fronts of about F- shape, a yoke structure 17 consisting of a front yoke 22, back yoke 23, center yoke 21 and side yokes 24 is constituted, permanent magnets 5 are fixed inside, a drive coil is movably inserted in the center yoke 21, and a linear voice coil motor 2 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic drive device constructed by combining a speed sensor and a linear voice coil motor.

[0002]

2. Description of the Related Art A linear voice coil motor having a structure in which a rotary motor is expanded and stretched in a straight line has the same principle as that of a dynamic speaker, and an eddy current magnetic field distribution generated in a conductor piece moving in a magnetic field is changed. The electromagnetic drive device in combination with the used speed sensor is used in a head drive unit of an optical disk device, a telephone card, cash card carrier, and the like. This electromagnetic drive device has advantages such as higher resolution than a drive device such as a step motor and does not require a drive conversion device such as a gear, and is often used in the above fields.

FIG. 8 is a schematic view of an electromagnetic drive device. The electromagnetic drive device 1 is composed of a linear voice coil motor 2 and a speed sensor 3 for detecting the movement of the linear voice coil motor 2. The speed sensor 3 includes a front yoke 4a, a back yoke 4b, both side yokes 4c and 4c.
A rectangular ring-shaped yoke structure 4 having a connection between
It is equipped with. Two permanent magnets 5 having an S pole and an N pole arranged vertically as shown in the figure are fixed inside the front yoke 4a, and a sensor coil 6 is movably fitted in a back yoke 4b.

The linear voice coil motor 2 has a yoke structure 7 corresponding to a structure in which the yoke structure 4 of the speed sensor 3 is stacked in two stages so that the upper and lower permanent magnets 5 face each other. The yoke structure 7 includes a front yoke 7a, a back yoke 7b, and two first and second center yokes 7 that are coupled and arranged in the middle of each yoke.
have d. The two center yokes 7d are connected to the front yoke 7a and the back yoke 7b by side yokes 7c.

Two permanent magnets 5 are fixed inside each of the front yoke 7a and the back yoke 7b. A drive coil 8 is movably fitted in the first and second center yokes 7d. The drive coil 8 and the sensor coil 6 are connected by a connecting member 9. The connecting member 9, the drive coil 8 and the sensor coil 6, which are these moving systems, are movably supported by guide rails (not shown).

In the electromagnetic drive device 1 described above, when a drive current of a predetermined pulse is applied to the drive coil 8 placed in a magnetic field through the lead wire 10, the drive coil 8 vibrates due to electromagnetic induction. Further, the vibration of the drive coil 8 causes the sensor coil 6 to vibrate via the connecting member 9, whereby an induced current also flows in the sensor coil 6, and this current is output as a detected current via the lead wire 11.

As described above, it is possible to energize the drive coil 8 to drive the linear voice coil motor 2 and to detect the moving speed thereof via the sensor coil 6 of the speed sensor 3.

Speed sensor 3 in the electromagnetic drive device 1
The yoke structure 4 and the yoke structure 7 of the linear voice coil motor 2 are conventionally configured as shown in FIGS. 9 and 10. That is, the yoke structure 4 of the speed sensor 3 is configured by combining one divided front yoke 4a, one divided back yoke 4b, and two side yokes 4c. In addition, the linear voice coil motor 2
The yoke structure 7 has one front yoke 7a and one front yoke 7a.
One back yoke 7b and two center yokes 7d
And four side yokes 7c were combined.

[0009]

In the conventional yoke structure, the number of parts of each yoke member is large, and accordingly, the number of joints of each yoke member is increased. Due to the large number of voids formed in the joints, magnetic flux leakage occurs. However, there is a problem in that the magnetic efficiency decreases due to the increase of the magnetic field. That is, the yoke structure 4 of the speed sensor 3 has four air gaps (joint portions of the yoke members) S, and the yoke structure 7 of the linear voice coil motor 2 has ten air gaps S. The magnetic flux leakage increases in proportion to the number of these voids S.

In order to improve the magnetic efficiency, the thickness of each yoke member may be set to about 5 mm or more, but in this case, it is difficult to process the yoke by pressing, and the soft magnetic material is cut or sintered. Will be processed,
There was a drawback that the cost inevitably increased.
In particular, when making a long-stroke linear voice coil motor, it is necessary to increase the thickness of the yoke member in order to maintain the strength. In this case, a plurality of plates are laminated to form the yoke structure, but in addition to the above-mentioned space S, the space is further increased, and the magnetic flux leakage is accordingly increased. In addition, magnetic flux leakage occurs even if the lamination direction of the thin plates is made parallel to the direction of the magnetic flux, and in this case there is a problem with the mechanical strength. It was difficult to manufacture the yoke structure.

It is an object of the present invention to provide a velocity sensor and a linear voice coil motor for an electromagnetic drive device, and an electromagnetic moving device equipped with these, which have improved the above drawbacks.

[0012]

In a velocity sensor for an electromagnetic moving device according to the present invention, a yoke structure is formed by integrally forming a first substantially Y-shaped front yoke member and a second yoke member in reverse. Face each other, and fix both ends of each yoke member to each other by abutting and fixing the yoke members to each other to form a front yoke, a back yoke, and a rectangular laminated yoke having two side yokes. It is characterized in that it is fixed and the sensor coil is movably fitted in the back yoke.

In the linear voice coil motor of the electromagnetic moving device according to the present invention, the yoke structure is integrally molded, and the first yoke member and the second yoke member, which are substantially F-shaped in the front, are opposed to each other in opposite directions. The end portions of the respective yoke members are abutted and fixed to each other to form a laminated yoke having a front yoke, a back yoke, and a center yoke, and a permanent magnet is fixed inside the front yoke and the back yoke.
A feature is characterized in that a drive coil is movably inserted into the center yoke.

Further, the yoke intermediate portions are thinnest outside the front yoke and the back yoke of the respective yoke structures of the speed sensor and the linear voice coil motor.
A notch becomes thicker toward both ends of the yoke, and in the linear voice coil motor, in addition to the notch, inside the center yoke,
It is preferable to form a notch in a space portion in which the middle portion of the yoke has the maximum width and becomes narrower toward both ends of the yoke.

The electromagnetic device according to the present invention is characterized in that the sensor coil of the speed sensor and the drive sensor of the linear voice coil motor are connected using a connecting means.

[0016]

According to the above construction, each yoke structure of the speed sensor and the linear voice coil motor is composed of a combination of a first yoke member and a second yoke member, which are integrally molded and which are substantially L-shaped and F-shaped. Since it is configured, the number of voids generated in the abutting portion of each yoke member is reduced, and the magnetic flux leakage is reduced by the amount of the reduced voids. Further, the weight of the yoke structure is reduced by the notch and the space formed in the yoke member. Moreover, since both ends of the yoke where the magnetic flux is concentrated have a required thickness and the magnetic flux density is kept constant, both ends of the yoke do not generate heat.

[0017]

Embodiments of the present invention will now be described with reference to the drawings.

1 and 2 are a perspective view and a front view of a speed sensor 3 of an electromagnetic drive device 1 and yoke structures 14 and 17 of a linear voice coil motor (hereinafter abbreviated as LVCM) 2, respectively.

In the speed sensor 3 of this embodiment, the yoke structure 14 includes a first yoke member 14a having a substantially L-shaped front surface, and a second yoke member 14a.
It is configured by combining the yoke members 14b. Then, the first yoke member 14a and the second yoke member 1
The yoke structure 1 has a rectangular outer shape when viewed from the front and has a space inside as shown in FIG.
4 is formed. That is, the yoke structure 14 has a front yoke 18, a back yoke 19, and both side yokes 20. Two permanent magnets 5 having an S pole and an N pole arranged as shown in the figure are fixed inside the front yoke 18.

In the LVCM 2 of this embodiment, the yoke structure 17 is constructed by combining a first yoke member 17a and a second yoke member 17b which are substantially F-shaped on the front surface. Then, the first yoke member 17a and the second yoke member 1
7b and face each other in the opposite direction, and by abutting the tips of the long portion, the short portion, and the vertical portion of each, a substantially "Sun" shape is seen from the front as shown in Figs. 1 and 2. The yoke structure 17 is formed. That is, the yoke structure 17 includes a center yoke 21, a front yoke 22 above the center yoke 21, a back yoke 23 below, and both side yokes 24. Two permanent magnets 5 are provided inside the upper and lower front yokes 22 and 23, respectively.

In the yoke structure 14 of the speed sensor 3 according to this embodiment, as can be seen from the figure, there are only two voids S between the first and second yoke members 14a and 14b,
Compared with the conventional number of four air gaps S, the number of air gaps can be reduced to 4-2 = 2, and two air gaps can be reduced. As the number of air gaps is smaller, the leakage magnetic flux generated in the yoke structure 14 is reduced.

In the above-mentioned yoke structure 14, the first structure
The second yoke members 14a and 14b may be formed by stacking a plurality of thin plates instead of using a conventional single plate having a large plate thickness. For example, if a plurality of soft magnetic plates with a thickness of about 1 mm are laminated to form the first and second yoke members 14a and 14b having a predetermined thickness as shown in FIG. Becomes cheaper. further,
By constructing the yoke structure 14 by laminating thin plates, the influence of eddy current loss can be suppressed to a low level and a high speed sensor can be easily realized.

In the yoke structure 17 of the LVCM 2 according to this embodiment, as can be seen from the figure, the first and second yoke members 1 are formed.
Since only three voids S are formed between 7a and 17b, it is possible to reduce the number of voids by 10-3 = 7, which is 7 compared to the conventional number of 10 voids, and the number of voids is small. Accordingly, the leakage magnetic flux generated in the yoke structure 17 is reduced. Moreover, since the air gap S in the middle of the center yoke 21 is a place where the magnetic fluxes originally cancel each other and do not flow, even if there is the air gap S at this position, the influence on the characteristics is small. Further, by constructing the yoke structure 17 by laminating thin plates, the influence of the eddy current loss can be suppressed to a low level.
It is possible to drive the VCM 2 at high speed.

FIG. 3 shows the speed sensor 3 shown in FIG. 1 and the LVC.
In the electromagnetic drive device 1 in which the sensor coil 6 and the drive coil 8 are respectively incorporated in the respective yoke structures 14 and 17 of M2 and which are connected using a connecting member 9 indicated by a dotted line, and in the respective yoke structures 14 and 17. It is explanatory drawing which shows the direction of the magnetic flux which flows. According to the electromagnetic drive device 1 of the present embodiment, by energizing the drive coil 8 of the LVCM 2 similarly to the conventional example, the drive coil 8 vibrates in the piston by the electromagnetic induction action,
This movement can be taken out as a driving force of an arbitrary driven member (not shown). Further, the vibration of the drive coil 8 is transmitted to the sensor coil 6 of the speed sensor 3 via the connecting member 9 and vibrates. When the sensor coil 6 moves in the magnetic field, an induced current flows in the sensor coil 6,
By detecting the change in the induced current, it is possible to detect the speed of the drive coil 8 which is interlocked with the sensor coil 6.

In this case, since the number of voids S generated in each of the yoke structures 14 and 17 of the speed sensor 3 and the LVCM 2 is small, the magnetic efficiency is good, and the electromagnetic drive device can be driven at high speed with less power consumption and can be driven. The speed can be detected accurately.

FIG. 4 is a perspective view of the speed sensor 3 and each yoke structure 14, 17 of the LVCM 2 according to the second embodiment of the present invention. In the figure, the yoke structure 14 of the speed sensor 3 is shown.
Is formed by first and second yoke members 14a and 14b having a substantially L-shape, and along the magnetic gradient of the magnetic flux lines of the permanent magnets 5 on the outer surfaces of the front yoke 18 and the back yoke 19 of the yoke structure 14. The middle portion 25 has a minimum width, and a substantially tapered notch portion 26 is formed in which the width is gradually increased toward both sides.

The yoke structure 17 of the LVCM 2 is formed by first and second yoke members 17a and 17b having a substantially F shape, and is permanently formed on the outer surfaces of the front yoke 22 and the back yoke 23 of the yoke structure 17. Along the magnetic gradient of the magnetic flux lines of the magnet 5, the intermediate portion 25 has a minimum width, and the width is gradually increased toward both sides.
6 is formed. Further, a diamond-shaped space 28 is formed by disposing the two substantially V-shaped notches 27 facing each other in the center yoke 21 of the yoke structure 17.

According to each of the above-mentioned yoke structures 14 and 17, since the notch portion 26 and the space 28 are formed, the weight of the yoke structure can be reduced accordingly. Moreover, the notch 26 has a substantially tapered shape, the space 28 has a substantially rhombic shape, and the both ends of the yoke on which the magnetic flux is concentrated have a sufficient yoke width, so that the magnetic flux is made uniform and the yoke structure is formed. 14,
No heat is generated at both ends of 17 due to magnetic resistance, and characteristics are not deteriorated.

The speed sensor 3 and the notches formed by cutting in the yoke structures 14 and 17 of the LVCM 2 are shown in FIGS.
It may be formed as in the third to fifth embodiments shown in FIG. Figure 5
In the third embodiment shown in FIG. 3, the front yokes 18, 22 and the back yokes 19, 23 of the yoke structures 14, 17 of the speed sensor 3 and the LVCM 2 respectively have a narrow bottom portion of a predetermined length at both ends thereof. A substantially "eight" -shaped notch 29 having continuous inclined portions is formed. In addition, a substantially long hexagonal space 30 is formed in the center portion of the center yoke 21 by facing the "eight" shaped notches 29. The other structure is the same as that of each yoke structure of the second embodiment.

In the fourth embodiment shown in FIG. 6, the speed sensor 3
And the front yokes 18, 22 and back yokes 19, 23 of the respective yoke structures 14, 17 of the LVCM 2 have a small-width bottom portion of a predetermined length, and both ends thereof have a substantially dish-shaped cut shape in which inclined portions are continuous with curved surfaces. The notch 31 is formed. In addition, a substantially boat-shaped space 32 is formed in the center of the center yoke 21 by facing the substantially dish-bottomed notch 31. The other structure is the same as that of the yoke structures of the second and third embodiments.

In the fifth embodiment shown in FIG. 7, the speed sensor 3
A notched portion 33 having a substantially arc shape is formed outside the front yokes 18 and 22 and the back yokes 19 and 23 of the respective yoke structures 14 and 17 of the LVCM 2. The arc-shaped notch 33 is made to face the center portion of the center yoke 21 so that the space 3 having a substantially lens cross-sectional shape is formed.
4 are formed. The other structures are the same as those of the yoke structures of the second, third and fourth embodiments.

The present inventor created a prototype for each of the above-mentioned examples and analyzed the magnetic field. According to the result, the uniform magnetic flux and the yoke structure are formed in the order of the substantially arcuate notch, the substantially dish-bottom notch, the substantially taper notch, and the substantially 8-shaped notch. It was confirmed that the weight reduction was achieved and good results with characteristics were obtained. The shape, size, etc. of the cutout portion are not limited to those in the embodiment.

[0033]

As described above, according to the present invention, the number of combined parts of the speed sensor of the electromagnetic drive device and the yoke member constituting the yoke structure of the linear voice coil motor is reduced, and the joint surface of the yoke member is reduced. Since the number of the air gaps generated in 1 is reduced, the leakage magnetic flux is reduced, the magnetic efficiency is improved, and the performance of the electromagnetic drive device is improved. Moreover, assembling becomes easier because the number of combined parts of the yoke members is reduced.

Further, as the magnetic efficiency is improved, it becomes possible to construct the yoke structure by laminating thin plates, and by laminating the thin plates which can be easily pressed, the yoke structure having a required thickness can be manufactured at low cost. Can be created with.

Further, the yoke structure is formed with notches in which the yoke middle portion is thin and the both ends of the yoke are gradually thicker along the gradient of the magnetic force lines, thereby reducing the weight of the yoke without impairing the magnetic characteristics. Became possible.

[Brief description of drawings]

FIG. 1 is a perspective view of a yoke structure of an electromagnetic drive device according to a first embodiment.

FIG. 2 is a front view of FIG.

FIG. 3 is a front explanatory view showing the flow of magnetic flux of the electromagnetic drive device.

FIG. 4 is a perspective view of a yoke structure of an electromagnetic drive device according to a second embodiment.

FIG. 5 is a front view of a yoke structure according to the third embodiment.

FIG. 6 is a front view of the yoke structure according to the fourth embodiment.

FIG. 7 is a front view of the yoke structure according to the fourth embodiment.

FIG. 8 is a perspective view of a conventional electromagnetic drive device.

FIG. 9 is a perspective view of a yoke structure of the electromagnetic drive device.

FIG. 10 is a front view of FIG. 9.

[Explanation of symbols]

1 ... Electromagnetic drive device, 2 ... Linear voice coil motor (L
VCM), 3 ... Speed sensor, 5 ... Permanent magnet, 6 ... Sensor coil, 8 ... Drive coil, 9 ... Connecting member, 14 ... Yoke structure, 14a ... First yoke member, 14b ... Second yoke member, 17 ... Yoke structure, 17a ... first yoke member,
17b ... 2nd yoke member, 26 ... Notch part, 28 ... Space, 29 ... Notch part, 31 ... Space, S ... Void.

Claims (5)

[Claims] 1. A front yoke including a permanent magnet, and a back yoke in which a sensor coil is movably fitted and inserted, wherein the yoke structure is integrally formed into first and second substantially L-shaped front faces. Speed sensor characterized in that the yoke members of the above are opposed to each other in opposite directions, and both ends of each yoke member are butted and fixed to each other to form a rectangular laminated yoke having a front yoke, a back yoke, and two side yokes. . 2. The speed sensor according to claim 1, wherein a cutout portion is formed on the outside of the front yoke and the back yoke, the yoke intermediate portion having a minimum wall thickness and a wall thickness increasing toward both ends of the yoke. . 3. A linear voice coil motor comprising a front yoke and a back yoke containing permanent magnets, and a center yoke having a drive coil movably fitted therein. In the linear voice coil motor, each of the yoke structures is integrally formed on the front surface. A stack including a front yoke, a back yoke, a center yoke, and a side yoke, with the substantially F-shaped first and second yoke members facing each other in opposite directions, the ends of each yoke member being butted and fixed to each other. A linear voice coil motor characterized by using a yoke. 4. A cutout portion is formed outside the front yoke and the back yoke so that the yoke intermediate portion is thinnest and becomes thicker toward both ends of the yoke. Inside the center yoke, a yoke intermediate portion is formed. 4. The linear voice coil motor according to claim 3, wherein a space portion having a maximum width is formed so as to become narrower toward both ends of the yoke. 5. A speed sensor having a front yoke containing a permanent magnet, a back yoke having a sensor coil movably fitted therein, a front yoke and a back yoke containing a permanent magnet, and a drive coil as a center. An electromagnetic drive device comprising: a linear voice coil motor movably inserted into a yoke; a sensor coil of the speed sensor; and a connecting means for connecting the drive coil of the linear voice coil motor, In the yoke structure of the sensor, the first yoke member and the second yoke member, each of which is integrally molded and has a substantially L-shaped front surface, are opposed to each other in opposite directions, and both ends of each yoke member are abutted and fixed together to form a front yoke. A rectangular laminated yoke having a back yoke and two side yokes, and a yoke structure of the linear voice coil motor. Body, a first yoke member each integrally molded front substantially F-shaped, second
An electromagnetic drive device characterized in that a yoke member is opposed to each other in an opposite direction, and ends of the respective yoke members are abutted and fixed to each other to form a laminated yoke having a front yoke, a back yoke, a center yoke, and a side yoke.