JP2001145323A - Electromagnetic drive and light quantity adjusting device therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the outer diameter of the whole electromagnetic drive from being enlarged, and assembly from being degraded because a rotor magnet is surrounded by a coil. SOLUTION: This electromagnetic drive is provided with a rotor having a magnet 11 magnetized into two poles on its outer periphery, a coil bobbin 8 disposed on the rotor in one axial direction, a first stator yoke 4 extending from one axial end of the coil bobbin to a position facing the outer periphery of the rotor, a second stator yoke 3 extending from the other axial end of the coil bobbin to the position facing the outer periphery of the rotor, and a third stator yoke 10 extending axially through the inner periphery of the coil bobbin and magnetically connecting the first and second stator yokes. The third stator yoke is assembled to the first stator yoke from the other axial direction, and the coil bobbin, the second stator yoke, and the rotor are assembled to the third stator yoke from the other axial direction.

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 for driving a rotor having a magnet by a magnetic circuit generated by energizing a coil.
The present invention relates to an electromagnetic drive device suitable as a drive source of a light amount adjustment device mounted on an optical device such as a video or digital camera.

[0002]

2. Description of the Related Art Conventionally, as proposed in Japanese Utility Model Laid-Open Publication No. Hei 7-14443, this type of electromagnetic driving device supports a rotor magnet rotatably and a coil bobbin so as to cover a bearing portion thereof. And a stator yoke arranged to face the rotor magnet.

[0003]

However, in the above conventional example, the coil is wound so as to cover the bearing portion outside the rotor magnet, and the yoke needs to be arranged at a position where it does not interfere with the coil. Has the following disadvantages.

That is, since the rotor magnet is surrounded by the coil, the projected area of the coil as viewed from the optical axis side is large, and the height is further increased, so that the outer diameter of the entire driving device is increased. Also, since the coil covers the magnet, the assemblability is poor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electromagnetic drive device capable of reducing the size (particularly, the diameter) and improving the assemblability, and a light amount adjusting device including the same.

[0006]

In order to achieve the above object, according to the present invention, there is provided a rotor having a magnet with two poles magnetized on the outer periphery thereof, and a coil bobbin disposed on one side in the axial direction with respect to the rotor. A first stator yoke extending from one axial end of the coil bobbin to a position facing the outer peripheral surface of the rotor; and a second stator yoke extending from the other axial end of the coil bobbin to a position facing the outer peripheral surface of the rotor. And a third stator yoke that extends axially through the inner periphery of the coil bobbin and magnetically couples the first and second stator yokes. A third stator yoke is attached to the stator yoke from the other side in the axial direction, and a coil bobbin, a second stator yoke, and a rotor are attached to the third stator yoke. So that attaching the other axial.

That is, the coils are arranged side by side in the axial direction with respect to the rotor, and the first and second stator yokes are formed so as to extend in the axial direction from each end of the coil bobbin to a position facing the outer peripheral surface of the rotor. Therefore, the outer diameter of the electromagnetic drive device is made equal to the outer diameter of the rotor and the first and second
The thickness of the stator yoke in the radial direction and the sum of the gap between the rotor and the stator yoke are sufficient.
The size (particularly, the diameter) of the electromagnetic drive device is reduced.
Moreover, at the time of assembling the electromagnetic drive device, all the other components are in the same direction (the other axial direction) with respect to the first stator yoke.
This facilitates assembly, and particularly facilitates automatic assembly.

The electromagnetic drive device is configured such that the coil bobbin is positioned in the circumferential direction by engagement with the first stator yoke, and the second stator yoke is positioned in the circumferential direction by engagement with the coil bobbin. It is preferable to improve the assembling accuracy.

[0009] Further, since the rotor is rotatably supported by the other end in the axial direction of the third stator yoke, it is desirable to simplify the structure and reduce the size without requiring a separate member for supporting rotation. .

In the case where the electromagnetic driving device having such a configuration is mounted as a driving source of a light amount adjusting device such as a shutter or an aperture, the electromagnetic driving device is arranged so that the axial direction is substantially parallel to the optical axis, and If the electromagnetic drive device is attached to the light amount control device main body such that the outer periphery of the electromagnetic drive device is located inside the outer periphery of the light amount control device main body in the direction view, the diameter of the light amount control device can be reduced in conjunction with the downsizing of the electromagnetic drive device. It becomes possible.

[0011]

FIG. 1 is an exploded perspective view of an electromagnetic drive (hereinafter referred to as a motor) according to an embodiment of the present invention.

In this figure, reference numeral 3 denotes a second stator yoke, which has a flange portion 3c orthogonal to the motor shaft and a substantially arc shape as viewed in the motor axis direction.
c and the rotor facing portion 3b that is raised from the position c. A fitting hole 3a penetrating in the motor axis direction is formed in the flange portion 3c.

Reference numeral 4 denotes a first stator yoke, which has a flange portion 4c perpendicular to the motor shaft and a substantially arc shape as viewed in the motor axis direction. And a start-up unit. A fitting hole 4a penetrating in the motor axis direction is formed in the flange portion 4c.

Reference numeral 10 denotes a third stator yoke formed in a shaft shape extending in the motor axis direction, and has a bearing portion 10a at an upper end thereof and a fitting portion 10b at a lower end thereof. Reference numeral 8 denotes a coil bobbin having a substantially hollow cylindrical shape, and a coil 9 is wound around the body. Fitting grooves 8b and 8c are formed at the upper end and the lower end of the bobbin 8, respectively.

Reference numeral 5 denotes a drive arm, which has a rotary shaft 5b and a blade drive pin 5a provided at a position radially away from the rotary shaft 5b. A ring-shaped magnet 11 is joined to the outer periphery of the lower cylindrical portion of the drive arm 5. On the outer periphery of the magnet 11, N and S poles are divided and magnetized in the circumferential direction. The rotor is constituted by the drive arm 5 and the magnet 11.

When assembling the motor from these components, first, the fitting portion 10b of the third stator yoke 10 is inserted into the fitting hole 4c of the first stator yoke 4 from above (the other axial end in the claims). The bobbin 8 is attached to the outer periphery of the third stator yoke 10. This allows
The third stator yoke 10 has a shape penetrating the center hole 8 a of the bobbin 8.

At this time, the fitting groove 8b of the bobbin 8 and the flange portion of the first stator yoke 4 (having a shape in which both sides in the radial direction are cut linearly according to the shape of the fitting groove 8b).
4c. Thereby, the bobbin 8 is positioned with respect to the first stator yoke 4 in the circumferential direction. Further, by joining the upper surface of the flange portion 4c and the lower surface of the bobbin 8, the bobbin 8 is also positioned with respect to the first stator yoke 4 in the motor axial direction.

Next, a portion of the third stator yoke 10 protruding from the upper surface of the bobbin 8 (a portion below the bearing 10a of the third stator yoke 10) is provided with a second
The fitting hole 3a of the stator yoke 3 is fitted from above.
At this time, the rotor facing portion 3b of the second stator yoke 3 has a phase relationship radially facing the rotor facing portion 4b of the first stator yoke 4.

The fitting groove 8c of the bobbin 8 and the flange portion of the second stator yoke 3 (having a shape in which both sides in the radial direction are linearly cut in accordance with the shape of the fitting groove 8c) 3c
And are fitted. Thereby, the second stator yoke 3 is positioned in the circumferential direction with respect to the bobbin 8, that is, with respect to the first stator yoke 4.

Further, by joining the lower surface of the flange portion 3c and the upper surface of the bobbin 8, the second stator yoke 3 is positioned in the motor axial direction with respect to the first stator yoke 4. The first and second stator yokes 4, 3
Are integrated via a third stator yoke 10 and are magnetically coupled when the coil 9 is energized.

A shaft hole formed in the lower surface of the cylindrical portion of the drive arm 5 is formed in the bearing portion 10a of the third stator yoke 10 projecting above the flange portion 3c of the second stator yoke 3, as shown in FIG. 5c is fitted from above.
The fitting between the bearing portion 10a and the shaft hole 5c is a light fitting that allows the drive arm 5 to rotate. Accordingly, the outer peripheral surface (magnetized portion) of the magnet 11 joined to the drive arm 5 faces the rotor facing portions 4b, 3b of the first and second stator yokes 4, 3. For this reason, when the coil 9 is energized, the first to third stator yokes 4, 3, 1
The drive arm 5 rotates according to the magnetic circuit formed at zero.

FIGS. 2 and 3 show a shutter (light amount adjusting device) provided with the above-mentioned electromagnetic driving device when viewed from the optical axis direction. FIG. 4 shows an SS cross section of FIG. In this figure, reference numeral 1 denotes a shutter base plate, which has a light-passing opening 1a and an arc-shaped window 1b into which a driving pin 5a is inserted, and a pin 1d is attached by press fitting or the like. A bearing hole 1c is formed near the outer periphery of the shutter base plate 1, and a rotating shaft 5b of the motor is inserted into the bearing hole 1c.

As shown in FIG. 2 and FIG. 3, the outer periphery of the motor (the second
The outer periphery of the stator yoke 3) is located inside the outer periphery of the shutter base plate 1 (and a holding plate 2 described later).

Reference numerals 6 and 7 denote shutter blades having substantially arc-shaped light shielding portions 6a and 7a. The shutter blade 7 is rotatably fitted to the pin 1d, and a slot 7b formed in the shutter blade 7 is fitted to the drive pin 5a of the drive arm 5.

The shutter blade 6 is a rotary shaft 5 of the drive arm 5.
b, is rotatably fitted to the shutter blade 6, and a slot 6b formed in the shutter blade 6 is fitted to the drive pin 5a. 2, shutter blades 6 are provided between the shutter base plate 1 and the shutter blades 6, as shown in FIG.
7, which has an opening 2a slightly larger than the opening 1a.

In the shutter constructed as described above, when the coil 9 is energized in the state of FIG. 2, the drive pin 5a integral with the rotor rotates clockwise in the window 1b. This movement is transmitted to the shutter blades 6 and 7 via the slots 6b and 7b, and the shutter blade 6 rotates clockwise about the rotation shaft 5b, and the shutter blade 7 rotates counterclockwise about the pin 1d. Move.

As a result, the shutter blades 6 and 7 are in the state shown in FIG. 3, and the camera on which the shutter is mounted exposes the film or the image pickup device. And
After a lapse of a predetermined time, a current is supplied in the opposite direction
In FIG. 3, the drive pin 5a rotates counterclockwise in FIG. 3, and the shutter blades 6 and 7 both rotate in the opposite direction to the above, closing the opening 1a and returning to the state of FIG. Return.

As described above, in this embodiment, the rotors 5, 1
The first and second stator yokes 4 and 3 are arranged in the motor axial direction from each end of the coil bobbin 8 to a position facing the outer peripheral surfaces of the rotors 5 and 11. , So that the outer diameter of the electromagnetic driving device is equal to the outer diameter of the rotors 5 and 11,
Radial thicknesses of the first and second stator yokes 4, 3;
The size is the sum of the gap between the rotor and the stator yoke. Therefore, it is possible to reduce the size (particularly, the diameter) of the electromagnetic drive device.

In assembling the motor, the third stator yoke 10 is assembled to the first stator yoke 4 from above in the motor axial direction (the other in the axial direction) in FIG.
Further, the coil bobbin 8, the second stator yoke 3, and the rotors 5, 11 are assembled to the third stator yoke 10 from above in the motor axial direction (the other in the axial direction). That is, in the motor of the present embodiment, all the other components are assembled to the first stator yoke 4 from the same direction. Therefore, the assembling becomes easy, and it is particularly suitable for performing automatic assembling of the motor.

Further, the fitting groove 8a of the coil bobbin 8 is fitted to the flange portion 4c of the first stator yoke 4,
Further, by fitting the flange portion 3c of the second stator yoke 3 into the fitting groove 8b of the coil bobbin 8, the first and second stator yokes 4, 3 and the coil bobbin 8 are positioned in the circumferential direction. Accuracy can be improved.

Further, in the present embodiment, the rotation supporting portion 10a for rotatably supporting the rotors 5, 11 is formed at the upper end of the third stator yoke 10, so that a separate rotation supporting member is not required. In addition, the structure can be simplified and the size can be reduced.

In this embodiment, the case where the electromagnetic driving device is used as a driving source of a shutter which is one of the light amount adjusting devices has been described. However, the electromagnetic driving device of the present invention is also used as a driving source of a diaphragm. It can also be used as a driving source for other various devices.

[0033]

As described above, according to the present invention,
The coils are arranged side by side in the axial direction with respect to the rotor, and the first and second stator yokes extend in the axial direction from one end and the other end in the axial direction of the coil bobbin to a position facing the outer peripheral surface of the rotor. Therefore, the outer diameter of the electromagnetic drive is determined by the sum of the outer diameter of the rotor, the radial thickness of the first and second stator yokes, and the gap between the rotor and the stator yoke. Thus, the electromagnetic drive device can be reduced in size (in particular, the diameter can be reduced). Moreover, when assembling the electromagnetic drive device, all the other components can be assembled to the first stator yoke from the same direction (the other axial direction), so that the assembly is facilitated, and particularly the automatic assembly is facilitated. Can be performed.

If the coil bobbin is positioned in the circumferential direction by engaging with the first stator yoke, and the second stator yoke is positioned in the circumferential direction by engaging with the coil bobbin, the electromagnetic drive is achieved. The accuracy of assembling the device can be improved.

Further, since the rotor is rotatably supported by the other end in the axial direction of the third stator yoke, a separate member for supporting rotation is not required, and the structure can be simplified and the size can be reduced.

When the electromagnetic driving device having such a configuration is mounted as a driving source of a light amount adjusting device such as a shutter or an aperture, the electromagnetic driving device is set so that the axial direction is substantially parallel to the optical axis, and If the electromagnetic drive device is attached to the light amount control device main body such that the outer periphery of the electromagnetic drive device is located inside the outer periphery of the light amount control device main body in the direction view, the diameter of the light amount control device can be reduced in conjunction with the downsizing of the electromagnetic drive device. be able to.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an electromagnetic drive device according to an embodiment of the present invention.

FIG. 2 is an optical axis direction view (initial state) of a shutter provided with the electromagnetic driving device.

FIG. 3 is a view in the optical axis direction of the shutter (opened state).

FIG. 4 is a sectional view taken along the line SS in FIG. 3;

[Explanation of symbols]

 Reference Signs List 1 shutter base plate 1a light passage opening 1d pin 2 holding plate 3 second stator yoke 4 first stator yoke 3a, 4a, 8a fitting hole 3b, 4b rotor facing portion 5 drive arm 5a drive pin 5b rotary shaft 6, 7 shutter blade Reference Signs List 8 coil bobbin 9 coil (winding) 10 third stator yoke 10a bearing part 10b fitting part 11 magnet 3c, 4c flange part 8a, 8b fitting groove

Claims (5)

[Claims] 1. A rotor having a magnet with two poles magnetized on its outer periphery, a coil bobbin disposed axially on one side of the rotor, and an outer peripheral surface of the rotor from one axial end of the coil bobbin. A first stator yoke extending in the axial direction to a position opposing the outer periphery of the coil bobbin; a second stator yoke extending in an axial direction from the other axial end of the coil bobbin to a position opposing the outer peripheral surface of the rotor; A third stator yoke extending axially through the inner periphery and magnetically coupling the first and second stator yokes; and a third stator yoke with respect to the first stator yoke. The third stator yoke is assembled from the other side in the axial direction, and the coil bobbin, the second stator yoke, and the An electromagnetic drive device wherein the rotor is assembled from the other side in the axial direction. 2. The positioning of the coil bobbin in the circumferential direction by engagement with the first stator yoke, and the positioning of the second stator yoke in the circumferential direction by engagement with the coil bobbin. The electromagnetic drive device according to claim 1, wherein: 3. The electromagnetic drive device according to claim 1, wherein the rotor is rotatably supported by the other end in the axial direction of the third stator yoke. 4. A light amount adjusting device comprising the electromagnetic drive device according to claim 1, wherein the light amount adjusting device is connected to the rotor and is driven to open and close by rotation of the rotor to adjust the light amount. 5. The electromagnetic drive device according to claim 1, wherein an axial direction of the electromagnetic drive device is substantially parallel to an optical axis, and an outer periphery of the electromagnetic drive device is located inside an outer periphery of a light amount adjusting device main body when viewed in an optical axis direction. The light amount adjusting device according to claim 4, wherein the light amount adjusting device is attached to the light amount adjusting device main body.