JP2003309940A - Electromagnetic drive apparatus, and light quantity adjusting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the electromagnetic drive apparatus of small size and low power consumption which is realized with a small drive which provides a high torque. <P>SOLUTION: The electromagnetic drive apparatus comprises a permanent magnet where a rotary shaft is disposed at the central part, an electromagnetic coil which is externally controlled for electrification, and a stator yoke which is so disposed as to face the permanent magnet and set to excited/non-excited state according to the electrification control of the electromagnetic coil. It rotates the rotary shaft by magnetic attraction and repulsion between the stator yoke and the permanent magnet. The permanent magnet is cylindrical and two poles are magnetized on an outer peripheral surface, with the cylinder oriented in the direction of magnetic line generated by the two poles. <P>COPYRIGHT: (C)2004,JPO

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 shutters, diaphragms and the like used in optical equipment such as digital cameras.

[0002]

2. Description of the Related Art Conventionally, as this type of electromagnetic drive device,
The permanent magnet rotor is composed of plastic magnets, and the rotor outer surface has two poles (N pole and S pole).
There has been proposed an electromagnetic drive device that is magnetized to rotate a rotary shaft integrally formed with a drive shaft for shutter blades and diaphragm blades by attraction and repulsion with a magnetomotive force generated by an exciting coil.

Further, in an electromagnetic drive device using a high magnetic material such as a neodymium-based compression magnet for the permanent magnet, a stator yoke, which is arranged to face the rotor and is composed of a drive lever that is press-fitted into the permanent magnet, An exciting coil for exciting the stator yoke, and attraction generated between the stator yoke and the permanent magnet;
It has been proposed to rotate a rotary shaft integrally formed with the drive shafts for the shutter blade and the diaphragm blade by the repulsive action.

By utilizing the rotation of the rotary shaft by these electromagnetic drive devices, it is possible to drive (for example, open and close the lens shutter blades) a light quantity adjusting device used in optical equipment such as a digital camera.

As described above, in recent products such as video cameras and still cameras that require a light quantity adjusting device, there is a strong need for downsizing and power consumption reduction. Therefore, the light quantity adjusting device is inevitably downsized. There is a demand for low power consumption.

There are two demands especially for miniaturization. One is that the distance from the light quantity adjusting member to the image pickup device such as CCD and the distance to the driving source for autofocusing and zooming are short, so that the light quantity is adjusted. It is intended to reduce the size (height) of the device in the optical axis direction. The other is that the lens barrel that holds the optical member basically has a circular cross section centered on the optical axis, and inside of it, a mechanism such as a light quantity adjusting device, autofocus, and zoom has a gap with the optical lens group. Therefore, there is a demand for these members to be housed in a cylinder that is as small as possible with the center of the optical axis.

[0007]

However, the above-mentioned conventional electromagnetic drive device has the following problems.

In the electromagnetic drive device in which the permanent magnet rotor is made of a plastic magnet, the torque is insufficient and it is difficult to reduce the size.

Further, even in an electromagnetic drive device using a highly magnetic material such as a compression magnet for the permanent magnet, the magnet cannot be made small in thickness in the direction of the magnetic force line. This point will be described in detail with reference to FIG. 7.

FIG. 7 is a sectional view showing the structure of a conventional magnet rotor for an electromagnetic drive device.

The permanent magnet 102 is a magnet rotor using a highly magnetic material such as a compression magnet. The rotating shaft 103 is attached to the upper and lower end surfaces of the magnet rotor.
a and 103b are attached. Permanent magnet 102
Is a cylindrical magnet whose outer peripheral surface is magnetized to have two poles (N pole and S pole) and is press-fitted in the central bearing portion of the drive lever 3 having the blade drive shaft 103c for compactness. , There is a problem that the wall thickness cannot be taken in the direction of the magnetic force line.

This is because the rotating shaft portion 10 of the drive lever 103 that holds the permanent magnet 102 even if the motor is downsized.
3a, 103b and the fitting portion of the magnet are the permanent magnet 1
The reason is that in order to secure the rotary strength for fixing 02, it can be reduced only to some extent. As a result, the permanent magnet inevitably becomes thin and thick, which causes a decrease in magnetic flux density = a decrease in driving torque, and it is necessary to increase power consumption in order to obtain a necessary driving force.

Therefore, in the conventional electromagnetic drive device, it was impossible to achieve both miniaturization and low power consumption.

In view of the above-mentioned conventional problems, it is an object of the present invention to provide an electromagnetic drive device or the like which enables high torque with a small drive unit and realizes both miniaturization and low power consumption.

[0015]

In order to achieve the above object, in an electromagnetic drive device of the present invention, a permanent magnet having a rotating shaft arranged at the center, an electromagnetic coil whose energization is controlled from the outside, and the permanent magnet. A stator yoke arranged to face the magnet and set to an excited / non-excited state in accordance with energization control of the electromagnetic coil, and the rotation due to magnetic attraction and repulsion between the stator yoke and the permanent magnet. In the electromagnetic drive device for rotating the shaft, the permanent magnet is magnetized to have two poles on its outer peripheral surface, and has a columnar shape with respect to a direction of a magnetic force line generated by the two poles.

The light quantity adjusting device of the present invention is characterized by including the electromagnetic drive device of the above invention.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment] <Structures of Electromagnetic Driving Device and Light Amount Adjusting Device> FIG. 1 is an exploded perspective view showing a structure of a light amount adjusting device equipped with an electromagnetic driving device according to a first embodiment of the present invention. 2 is a plan view of the electromagnetic drive device shown in FIG. 1, and FIG. 3 is a sectional view of the electromagnetic drive device shown in FIG. Further, FIG. 4 is a cross-sectional structural view of a magnet rotor that is a component of the electromagnetic drive device shown in FIG.

The light quantity adjusting device is configured as a shutter and a diaphragm device used in an optical device such as a digital camera.

Reference numeral 2 in the figure denotes neodymium (Nd-Fe).
-B) or a permanent magnet composed of a samarium k-based compression magnet. This permanent magnet 2
Is the blade drive shaft 3c due to insert formation or press fitting.
The magnet rotor 20 is configured as shown in FIG.

The outer peripheral surface of the permanent magnet 2 of the magnet rotor 20 is magnetized to have two poles (N pole and S pole).
That is, as shown in FIG. 2, the magnetized portion 2b is magnetized so as to have an S pole, and the magnetized portion 2a is magnetized so as to have an N pole. And the permanent magnet 2 is, as shown in FIG.
It is formed in a cylindrical shape with respect to the direction of magnetic force lines generated by the two poles.

Rotating shafts 3a and 3b are attached to the upper and lower end surfaces of the magnet rotor 20, respectively. As shown in FIG. 3, the rotary shafts 3a and 3b are rotatably fitted and held by the bearing hole portion 1a of the magnet of the shutter base plate 1 and the bearing hole portion 7a of the magnet cover 7.

Reference numeral 4 denotes a stator lower yoke made of a soft magnetic material, which is fixed to the shutter base plate 1. The stator lower yoke 4 has a magnetic pole portion 4a of a magnetic yoke arranged to face the magnetized portion 2a of the magnet rotor 20. 6
Is a yoke on the stator made of a soft magnetic material, and has a magnetic pole portion 6a of a magnetic material yoke arranged to face the magnetized portion 2b. Further, the stator upper and lower yokes 4 and 6 respectively have connecting portions 4b and 6b at the positions where the winding coils 5 are attached. The connecting portions 4b, 6b and the magnetic pole portions 4a, 6a are integrally formed on the stator and the lower yokes 4, 6 to form a magnetic circuit. The connecting portions 4b and 6b are pressed and connected by a bobbin to magnetically connect the magnetic pole portions 4a and 6a.

Reference numeral 5 denotes a winding coil made of a conductive wire, which is arranged on the stator and on the coil mounting portions 4b and 6d of the lower yokes 4 and 6 and wound.

Thus, the electromagnetic drive device has a structure as shown in FIGS.

Further, in FIG. 1, 8 is a shutter blade, 9 is a diaphragm blade, and a rotary shaft portion 3b of a magnet rotor 20 which is rotatably fitted to the shutter base plate 1 projects from the shutter base plate 1 to form a blade 8. , 9 are formed as supporting shafts, and the rotating shaft portion 3b is rotatably held by the main plate 1 by inserting the supporting shaft holes 8a, 9a of the shutter blade 8 and the diaphragm blade 9.

The shutter blade 8 and the diaphragm blade 9 are formed with elongated holes 8b and 9b, and the elongated blades 8b and 9b are provided with a blade drive shaft 3c formed on the magnet rotor 20.
Fits slidably. When the blade drive shaft 3c rotates together with the magnet rotor 20, the shutter blade 8
The aperture blade 9 and the aperture blade 9 rotate so as to open and close the aperture opening diameter portion 1c of the shutter base plate 1 or switch the aperture diameter.

Reference numeral 10 denotes a blade case, which is a shutter blade 8
The travel space is secured so that the diaphragm blade 9 can be pressed and the blade 8.9 can be rotated.

The light quantity adjusting device having such a configuration is arranged in the circumferential wall of the lens barrel of the camera or the like.

<Operation of Electromagnetic Driving Device and Light Quantity Adjusting Device>
Next, the operations of the electromagnetic drive device and the light amount adjustment device will be described.

When the coil 5 is not energized, the stator yokes 4 and 6 are in a non-excited state, and the magnetized portions 2a and 2b on the outer peripheral surface of the permanent magnet 2 and the stator yokes 4 and 6 arranged so as to face the permanent magnet 2. By the attraction force (day tent force) with the magnetic pole portions 4a, 6a of the
a and 2b are retained. When the magnet rotor 20 is in this position, the shutter blade 8 and the diaphragm blade 9
Is arranged in contact with a stopper member (not shown) formed on the shutter base plate 1 at the position shown.

From this state, the magnetic pole portion 4a of the stator yoke 4 becomes the N pole, and the magnetic pole portion 6a of the stator yoke 6 becomes S.
When the coil 5 is energized so as to become a pole, a repulsive force and an attractive force are generated between the stator yokes 4 and 6 and the magnet rotor 20, so that the magnet rotor 20 is rotated about 40 ° clockwise from the illustrated state. Rotate at an angle of 50 °.

As a result, the shutter blade 8 is rotated from the open state to the closed position, and the diaphragm blade 9 is rotated in the direction from the full aperture diameter position to the small aperture opening position.

Here, the permanent magnet 2 and the stator yoke 4,
The arrangement relationship of 6 is that the total operating angle of the magnet rotor 20 is 4
Approximately 20 to 25 degrees, which is half of 0 to 50 degrees
The day tent force is zero at the operating position, and the direction of the day tent is also switched to the left and right.

Therefore, even if the coil rotor 5 is energized and the magnet rotor 20 rotates the shutter blades 8 and diaphragm blades 9 and then the energization is turned off, the blades 8 and 9 are actuated by the detent force. It comes into contact with a stopper member arranged at the end position to make a stable stop.

On the other hand, the magnetic pole portion 4a of the stator yoke 4 is S
When the coil 5 is energized so that it becomes a pole and the magnetic pole portion 6a of the stator yoke 6 becomes an N pole, the stator yoke 4,
6, a repulsive force and an attractive force are generated between the magnet rotor 6 and the magnet rotor 20, and the magnet rotor 20 rotates counterclockwise from the state shown in the figure by an angle of about 40 ° to 50 ° and returns to the initial position.

As described above, the drive lever 3 integrated with the permanent magnet 2 is acted on by the two forces of magnetic repulsion and attraction by the energization of the coil 5, and the rotation levers 3a and 3b are used as the center. Then, it is driven and rotated to both ends of the long groove for which the operation range regulation is set, and is urged to both ends of the long groove by the detent force. It should be noted that the shutter base plate 1 is provided with a long groove portion that restricts the operation range of the blade drive shaft 3c of the drive lever 3.

As described above, in the drive control of the digital camera or the like, the opening / closing drive control of the shutter and the diaphragm is performed by controlling the forward and reverse currents to the coil 5, and in the drive control of the compact camera and the like, the coil is controlled. The opening / closing drive control of the shutter and the diaphragm is performed according to the time and timing of energization by turning on / off the current to the device 5.

Due to the miniaturization of the electromagnetic drive device, the conventional permanent magnet (cylindrical magnet) is press-fitted into the drive lever, so that the wall thickness of the permanent magnet in the direction of the magnetic force line cannot be secured. As a result, the magnetic flux density is lowered and the generated driving torque is lowered.

On the other hand, in this embodiment, as shown in FIG. 4, the outer peripheral surface of the permanent magnet 2 has two poles (N pole and S pole).
The permanent magnet 2 is magnetized in the direction of the generated magnetic field lines.
Since it has a cylindrical shape, it is possible to increase the magnetic flux density while ensuring a sufficient thickness even with a small permanent magnet. As a result, since the generated driving force (torque) can be increased, it is possible to configure a shutter or the like that can be driven at high speed without increasing power consumption even with a downsized driving device.

[Second Embodiment] In the first embodiment,
Although the columnar permanent magnet 2 is composed of a compression magnet, this embodiment is composed of a sintered anisotropic magnet, and the other structures are the same as those of the first embodiment.

FIG. 5 is a sectional structural view of a magnet rotor which is one component of the electromagnetic drive device according to the second embodiment of the present invention, and FIG. 6 is a sectional view taken along line AA of FIG.

In this embodiment, as the columnar permanent magnet 2, a sintered anisotropic magnet having magnetic field lines oriented on the outer peripheral surface thereof is accurately arranged at the point of use. Therefore, two poles (N pole and S pole) are formed on the outer peripheral surface of the cylindrical magnet.
Grooves 2c and 2d are provided on the boundary line of the magnetic poles magnetized to the poles, and the upper and lower rotary shaft portions 3a and 3b of the drive lever 3 holding the permanent magnet 2 are insert-molded by the grooves 2c and 2d.

The positions of the grooves 2c and 2d have no influence on the lines of magnetic force of the magnet and can be utilized for positioning the anisotropic magnet. That is, the arrangement angle of the drive lever 3 with respect to the magnetization point of the anisotropic magnet is determined.

Even with the configuration of this embodiment, the same effect as that of the first embodiment can be obtained.

[0046]

As described above in detail, according to the present invention, the permanent magnet is magnetized to have two poles on its outer peripheral surface, and has a cylindrical shape with respect to the direction of magnetic force lines generated by the two poles. Even with a small permanent magnet, it is possible to increase the magnetic flux density while ensuring sufficient wall thickness. As a result, the generated driving force (torque) can be increased without increasing the power consumption, so that it is possible to achieve both miniaturization and low power consumption.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a configuration of a light amount adjustment device equipped with an electromagnetic drive device according to a first embodiment of the present invention.

FIG. 2 is a plan view of the electromagnetic drive device shown in FIG.

3 is a cross-sectional view of the electromagnetic drive device shown in FIG.

4 is a cross-sectional structural view of a magnet rotor that is a component of the electromagnetic drive system shown in FIG.

FIG. 5 is a cross-sectional structural diagram of a magnet rotor that is a component of an electromagnetic drive device according to a second embodiment of the present invention.

6 is a cross-sectional view taken along the line AA of FIG.

FIG. 7 is a cross-sectional view showing a configuration of a conventional magnet rotor for an electromagnetic drive device.

[Explanation of symbols]

1 Shutter base plate 2 permanent magnet 3 drive lever 3a. 3b rotating shaft 3c Blade drive shaft 4 Lower stator yoke 5 coils 6 Stator upper yoke 7 magnet cover 8 shutter blades 9 diaphragm blades 10 feather case 20 magnet rotor

[Procedure amendment]

[Submission date] October 10, 2002 (2002.10.
10)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

Reference numeral 2 in the figure denotes neodymium (Nd-Fe).
-B) or a permanent magnet composed of Samaryuu beam system of the compression magnet. This permanent magnet 2
The magnet rotor 20 is configured as shown in FIG. 4 by being integrated with the drive lever 3 having the blade drive shaft 3c by insert formation or press fitting.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H080 AA19 AA20 AA55 AA61 AA64                 2H081 AA51 BB17                 5H622 AA03 CA01 CA05 CA07 CA12                       DD02 PP01 QA02                 5H633 BB03 GG02 GG05 GG09 GG12                       HH03 HH06 HH08 JA08

Claims (6)

[Claims] 1. A permanent magnet having a rotating shaft arranged at its center, an electromagnetic coil whose energization is controlled from the outside, and an electromagnetic coil which is arranged so as to face the permanent magnet and is in an excited / non-excited state according to energization control of the electromagnetic coil. In the electromagnetic drive device having a stator yoke set to, and rotating the rotary shaft by magnetic attraction and repulsion between the stator yoke and the permanent magnet, the permanent magnet has two poles on an outer peripheral surface. Is magnetized, and is configured in a cylindrical shape with respect to the direction of magnetic force lines generated by the two poles. 2. The electromagnetic drive device according to claim 1, wherein the permanent magnet is composed of a neodymium-based or samarium-based compression magnet. 3. The electromagnetic drive device according to claim 1, wherein the permanent magnet is composed of a sintered anisotropic magnet. 4. The two grooves are formed on the boundary line of the magnetic poles magnetized on the outer peripheral surface of the permanent magnet, and the two grooves form the rotary shaft formed on the drive lever holding the permanent magnet. The electromagnetic drive device according to claim 3, wherein the electromagnetic drive device has a structure of insert molding. 5. The electromagnetic drive device according to claim 1, wherein the rotary shaft and a blade drive shaft for driving a blade of a shutter and a diaphragm for an optical device are insert-molded. 6. A light amount adjusting device comprising the electromagnetic drive device according to claim 1.