JP2005328633A - Driver and quantity of light adjuster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a highly efficient, thin and inexpensive device by reducing an axial force generated in a rotating magnet as much as possible thereby reducing a force applied to a bearing. <P>SOLUTION: The driver comprises a coil 4 arranged outside the outer diameter of a magnet 1, a first stator 5 excited by the coil, and a second stator 6 excited by the coil. Assuming the overlap area of the first stator and the magnetized part of the magnet is S1, its total sum over the entire circumference is ΣS1, the overlap area of the second stator and the magnetized part of the magnet is S2, its total sum over the entire circumference is ΣS2, the distance between the first stator and the magnet is D1, and the distance between the second stator and the magnet is D2, a relation D1=D2 is satisfied when ΣS1=ΣS2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a driving device used in an optical device such as a camera and a light amount adjusting device including the driving device.

  As a thin actuator or motor, for example, in recent years, there is a demand as a driving source for shutters of digital cameras and the like that are becoming thinner, and a brushless type motor can be cited as a suitable form. A brushless type motor having a simple drive circuit includes a stepping motor using a permanent magnet. When this stepping motor is used as a driving source for shutter blades that open and close the shutter opening, there is an advantage that the control can be performed in steps, and therefore further miniaturization and thinning in the optical axis direction are desired.

As a thin drive device (motor) that is short in the optical axis direction, for example, there are those shown in FIGS. 13 and 14 (see Patent Document 1 and Patent Document 2). This is composed of a plurality of coils 301, 302, 303 and a disk-shaped magnet 304. The coils 301 to 303 have a thin disk shape as shown in the figure, and their axes are arranged in parallel with the rotating shaft 300 of the magnet 304. The disk-shaped magnet 304 is magnetized in the axial direction of the disk, and the magnetized surface of the magnet 304 and the cores of the coils 301 to 303 are disposed so as to face each other. As shown in the figure, in the configuration having the small rotating shaft 300 and the small-diameter smooth bearing 305 that supports the rotating shaft 300, the friction loss due to the axial force generated in addition to the rotating force is large even with the sliding bearing. There is no.
Japanese Patent Laid-Open No. 7-213041 JP 2000-50601 A

  However, with such a structure having the rotation shaft 300 in the center, it is impossible to use the central portion as an optical optical path in a camera shutter or the like. Therefore, if it is intended to be used for a camera shutter or the like, a driving device of this structure must be arranged in addition to the optical path, and as a result, the size in the planar direction is increased by adding the size of the driving device to the diameter of the optical path. There was a problem.

  When pursuing small size and thinness, necessary functions such as shutter speed cannot be achieved unless the efficiency of the apparatus is increased at the same time. Some actuators and stepping motors that achieve high efficiency include a magnet rotor sandwiched between stators excited by coils. This configuration is known to be a small but highly efficient drive source because the stator excited by the coil is in close proximity with the magnet sandwiched between them and the amount of electromagnetic force generated is large and the magnetic resistance is low. In this system, the magnet has a cylindrical shape, and the magnetic pole teeth of the excited stator are arranged and sandwiched on both the inner diameter side and the outer diameter side of the magnet so as to be configured as a cylindrical shape that is long in the direction of the rotation axis as a whole.

  On the other hand, in order to configure a thin, flat and highly efficient actuator or stepping motor that is short in the direction of the rotation axis, the rotating magnet is formed into a thin flat ring shape, and the coil is arranged on the inner or outer periphery of the magnet and excited. A configuration in which a magnet is sandwiched between the upper and lower sides in the axial direction with a fixed stator can be considered. Here, an output is obtained by a force attracting each other generated between the stator and the magnet close to the magnet, and the force generates an unnecessary axial force simultaneously with an effective rotational force. If this axial force is larger than necessary, the sliding friction loss will increase accordingly, so this is received by a bearing with a very smooth sliding surface to suppress the generation of frictional force and reduce the rotational torque loss of the device. It is necessary to prevent. However, in order to suppress the generation of the frictional force due to the axial force, it was necessary to use an expensive material with a costly finish and good slidability in order to make the bearing smoother than necessary.

  On the other hand, when used as a drive source for a shutter of a camera or the like as described above, since the center of the apparatus is an optical path, the form of the drive apparatus is a ring shape, but the fitting diameter of the magnet rotor bearing in that case Is inevitably larger in radius than the aperture of the optical path. That is, the amount of friction loss is obtained by multiplying the frictional force of the sliding portion by the radius of the portion, and as a result, there is a problem that the lost rotational torque is increased when the sliding friction is large.

  Thus, it has been difficult to construct a thin, high-efficiency, and inexpensive driving device suitable for a shutter of an optical device such as a camera.

(Object of invention)
An object of the present invention is to provide a thin, highly efficient and inexpensive driving device and light amount adjusting device by reducing the axial force generated in a rotating magnet as much as possible to reduce the force applied to the bearing.

  In order to achieve the above-mentioned object, the invention according to claim 1 is characterized in that a ring-shaped magnet that is divided into a plurality of pieces in the circumferential direction and is alternately magnetized on different poles, and the ring-shaped magnet is virtually centered on the ring-shaped magnet. With respect to the shaft serving as the rotation center of the magnet, a bearing that is rotatably held as a shaft, a coil disposed on the outside of the outside diameter of the magnet, on the inside of the inside diameter, on the outside of the outside diameter, and on the inside of the inside diameter. A first stator that is arranged to face one surface in the vertical direction, and is arranged to face the other surface in the direction perpendicular to the axis that is the rotation center of the magnet; In the driving device having the second stator excited by the coil, the overlapping area of the magnetized portion of the first stator and the magnet viewed from the axial direction is S1, and the entire circumference thereof. ΣS1 is the total sum across, the overlapping area S2 of the magnetized portion of the second stator and the magnet as viewed from the axial direction, ΣS2 is the sum total over the entire circumference, and the axial direction of the first stator and the magnet is the axial direction. When the distance is D1, the distance between the second stator and the magnet in the axial direction is D2, and when ΣS1 = ΣS2, the relationship between D1 and D2 is D1 = D2. .

  In the above configuration, when the overlapping areas of the first and second stators and the magnets are equal, the distance between the first stator and the magnet and the distance between the second stator and the magnet are also made equal so that the electromagnetic force in the axial direction of the magnet The loss is reduced by almost eliminating the force applied to the bearing.

  In order to achieve the above object, a second aspect of the present invention provides a ring-shaped magnet that is divided into a plurality of pieces in the circumferential direction and alternately magnetized to different poles, and the ring-shaped magnet is virtually centered on the ring-shaped magnet. With respect to the shaft serving as the rotation center of the magnet, a bearing that is rotatably held as a shaft, a coil disposed on the outside of the outside diameter of the magnet, on the inside of the inside diameter, on the outside of the outside diameter, and on the inside of the inside diameter. A first stator that is arranged to face one surface in the vertical direction, and is arranged to face the other surface in the direction perpendicular to the axis that is the rotation center of the magnet; In the driving device having the second stator excited by the coil, the overlapping area of the magnetized portion of the first stator and the magnet viewed from the axial direction is S1, and the entire circumference thereof. ΣS1 is the total sum across, the overlapping area S2 of the magnetized portion of the second stator and the magnet as viewed from the axial direction, ΣS2 is the sum total over the entire circumference, and the axial direction of the first stator and the magnet is the axial direction. The distance is D1, the distance between the second stator and the magnet in the axial direction is D2, and when ΣS1 <S2, the relationship between D1 and D2 is D1 <D2. .

  In the above configuration, when there is a difference in the overlapping area of the first and second stators and the magnets, the distance between the first stator and the magnets and the distance between the second stator and the magnets are made different from each other in the axial direction of the magnets. The electromagnetic force is made equal and almost no force is applied to the bearing to reduce the loss.

  Similarly, in order to achieve the above object, a third aspect of the present invention provides a ring-shaped magnet that is divided into a plurality of pieces in the circumferential direction and is alternately magnetized to different poles, and the ring-shaped magnet is virtually centered on the ring-shaped magnet. A bearing that is rotatably held as an axis of the magnet, a coil disposed on the outside or inside of the inside diameter of the magnet, or on the outside of the outside diameter and inside the inside of the inside of the magnet, and the shaft serving as the rotation center of the magnet The first stator, which is disposed opposite to one surface in the vertical direction and is excited by the coil, and the other surface in the direction perpendicular to the axis serving as the rotation center of the magnet. In the driving device having the second stator excited by the coil, the overlapping area of the magnetized portion of the first stator and the magnet viewed from the axial direction is S1, and The sum total over the entire circumference is ΣS1, the axial thickness of the first stator is T1, the axial distance between the first stator and the magnet is D1, and the second stator viewed from the axial direction. And the overlapping area S2 of the magnetized portions of the magnet, ΣS2 is the sum total over the entire circumference, T2 is the plate thickness in the axial direction of the second magnetic pole portion, and the axial direction of the second stator and the magnet is in the axial direction. When the distance is D2, and when ΣS1 <ΣS2 and D1≈D2, the drive device is such that the relationship between T1 and T1 is T1> T2.

  In the above configuration, if there is a difference in the overlapping area between the upper and lower stators and the magnet, the axial force of the magnet is made equal by changing the axial plate thickness of the upper stator and the lower stator, and applied to the bearing. Loss is reduced with almost no power.

  Similarly, in order to achieve the above object, a fourth aspect of the present invention provides a ring-shaped magnet which is divided into a plurality of pieces in the circumferential direction and alternately magnetized to different poles, and the ring-shaped magnet is virtually centered on the ring-shaped magnet. A bearing that is rotatably held as an axis of the magnet, a coil disposed on the outside or inside of the inside diameter of the magnet, or on the outside of the outside diameter and inside the inside of the inside of the magnet, and the shaft serving as the rotation center of the magnet The first stator, which is disposed opposite to one surface in the vertical direction and is excited by the coil, and the other surface in the direction perpendicular to the axis serving as the rotation center of the magnet. In the driving device having the second stator excited by the coil, the overlapping area of the magnetized portion of the first stator and the magnet viewed from the axial direction is S1, ΣS1, the overlapping area S2 of the magnetized portion of the second stator and the magnet as viewed from the axial direction, and ΣS2 as the sum over the entire circumference, when ΣS1 and ΣS2 are different, The stator and the second stator are made of a drive device in which the electromagnetic force acting between the magnet and the first and second stators is made equal by using materials having different magnetic characteristics. is there.

  In the above configuration, even when there is a difference in the overlapping area between the first and second stators and the magnet, the axial force of the magnets can be made equal by making the materials of the first stator and the second stator different. The loss is reduced by almost eliminating the force applied to the bearing. The magnetic characteristic is mainly the maximum magnetic flux density.

  Similarly, in order to achieve the above object, the invention described in claim 6 includes the driving device according to any one of claims 1 to 5 and a light amount adjusting member that is driven by the driving device to adjust the light amount. This is a light quantity adjusting device.

  According to the present invention, the axial force generated in the rotating magnet can be reduced as much as possible to reduce the force applied to the bearing, and a thin, highly efficient and inexpensive driving device or light amount adjusting device can be provided.

  This is as shown in Examples 1 to 4 below.

  1 to 6 are diagrams related to Embodiment 1 of the present invention, in which FIG. 1 is an exploded perspective view of the drive device, FIG. 2 is a partially enlarged view of the assembled drive device shown in FIG. FIG. 4 is a cross-sectional view of the driving device shown in FIG. 1 in an assembled state, and FIG. 4 is a top view showing only the magnet 1 and the first stator 5.

  In these figures, reference numeral 1 denotes a ring (thin flat) magnet made of a plastic magnet material or the like, and one surface perpendicular to the virtual axis serving as the ring-shaped rotation center and the other surface are arranged in the circumferential direction. And are alternately magnetized to the S and N poles. In addition, each back surface is an opposite pole. In this example, the number of magnetic poles is 16 poles, but the magnet may be 2 poles or more. A drive pin 1h is formed on the magnet 1 on the first stator 5 side to be described later in order to output the rotational torque.

  Reference numeral 2 denotes a ring that determines the position in the radial direction and the axial direction. The ring 2 is joined to the magnet 1 and the inner periphery thereof is fitted to the outer periphery of a bearing 3 to be described later and rotates smoothly while maintaining the same axis. The material is non-magnetic and has a very smooth sliding property. For example, plastic is made of polyacetal, Teflon (trademark), fluororesin, etc., so the axial sliding surface 2a is made of metal. Smoothness is not lost even when sliding with a first stator 5 and a second stator 6 described later. Further, the distance D11 between the first stator 5 and the magnet 1 and the distance D12 between the second stator 6 and the magnet 1 shown in FIG. 3 are the upper sliding surface 2a and the lower sliding surface 2a of the ring 2, respectively. And a gap between the magnet 1 and the position where the magnet 1 is joined. The gap between the magnet and the stator, which is important for generating the motor torque, is stably secured, and the predetermined amounts D11 and D12 are always secured.

  Reference numeral 3 denotes a bearing, which is a non-magnetic material that is smooth and has good slidability, for example, a plastic made of polyacetal, Teflon (trademark), fluorine resin, etc., and a ring integrated with the magnet 1 on its outer periphery. Rotate 2 smoothly. Reference numeral 4 denotes a ring-shaped coil, and the coil 4 is concentric with the magnet 1 and arranged on the outer diameter side of the magnet 1.

  Reference numeral 5 denotes a first stator made of a soft magnetic material, which is excited by energizing the coil 4. The first stator 5 has a flat comb-teeth shape that faces a plane (one surface) perpendicular to the axial direction of the ring-shaped magnet 1 with a predetermined gap and extends in the radial direction of the magnet 1 and in the inner diameter direction. It is comprised by the magnetic pole tooth 5a. The number of extending comb-shaped magnetic pole teeth 5a is ½ of the number n of magnetized divisions of the magnet 1, and these are equally divided by 720 / n degrees (45 degrees in this embodiment 1) (here Then, 8) are arranged. When the coil 4 is energized, the magnetic pole teeth 5a of the first stator 5 are all excited to have the same polarity.

  Reference numeral 6 denotes a second stator made of a soft magnetic material, which is excited by energizing the coil 4. The second stator 6 is opposed to a plane (the other surface) perpendicular to the axial direction of the ring-shaped magnet 1 with a predetermined gap, and is a flat comb-like shape extending in the radial direction of the magnet 1 and in the inner diameter direction. It is comprised by the magnetic pole tooth 6a. The number of extending comb-shaped magnetic pole teeth 6a is ½ of the number n of magnetized divisions of the magnet 1, and they are equally divided by 720 / n degrees (45 degrees in this embodiment 1) (here Then, 8) are arranged. By energizing the coil 4, all the magnetic pole teeth 6 a of the second stator 6 are excited so as to have the same polarity, and opposite to the magnetic pole teeth 5 a of the first stator 5. The magnetic pole teeth 6 a of the second stator 6 are formed at positions facing the magnetic pole teeth 5 a of the first stator 5 across the magnet 1. The first stator 5 and the second stator 6 are magnetically coupled by a standing wall-shaped upright portion 6j at the outermost peripheral portion of the second stator 6.

  The magnet 1, the coil 4, the first stator 5 and the second stator 6 constitute a magnetic circuit.

  Next, the electromagnetic force generated between the magnet 1 and the first stator 5 and the second stator 6 will be described with reference to FIG.

  FIG. 2 shows a state in which a portion of the magnet 1 that is divided and magnetized (the rear surface is an N pole) is positioned between the magnetic pole teeth 5 a of the first stator 5 and the magnetic pole teeth 6 a of the second stator 6. . When the coil 4 is energized in this state and the magnetic pole teeth 5a are excited to the north pole, an attractive force F is generated in which the central portion of the south pole of the magnet 1 is directed toward the center of the magnetic pole teeth 5a. However, since the magnet 1 is restrained in the axial direction by the ring 2 and the first stator 5, it is divided into an axial force F1 and a rotational force F2. Similarly, when the magnetic pole tooth 6a is excited to the south pole, an attractive force F ′ is generated in which the central portion of the north pole of the magnet 1 is directed toward the center of the magnetic pole tooth 6a. Since it is restrained by the second stator 6, it is divided into an axial force F1 'and a rotational force F2'. Here, the smaller the distance D11 which is the gap shown in FIG. 3, the smaller the attractive force F generated between the first stator 5 and the magnet 1, and the smaller the distance D12, the second the second. The attractive force F ′ generated between the stator 6 and the magnet 1 increases.

  In FIG. 4, overlapping portions of the magnet 1 and the first stator 5 viewed from the axial direction are indicated by hatched portions, each of which is S11, and the sum of the overlapping areas is ΣS11. Assuming that the overlapping portions of the two stators 6 viewed from the axial direction are S12 and the sum of the overlapping areas is ΣS2, the larger the sum ΣS11 of the overlapping areas of the first stator 5 and the magnet 1 is, the larger the first stator 5 is. At the same time, the attraction force F generated between the second stator 6 and the magnet 1 increases, and similarly, the larger the total sum ΣS12 of the overlapping areas of the second stator 6 and the magnet 1, the greater the attraction generated between the second stator 6 and the magnet 1. The force F ′ increases.

  These are based on the results of electromagnetic analysis and experiments by the finite element method. According to this, in the first embodiment, the total sums ΣS11 and ΣS12 of the overlapping areas are approximately equal, and the distances D11 and D12 are approximately equal. Therefore, the suction forces F and F ′ are substantially equal, and therefore the divided axial forces F1 and F1 ′ are also equal. As a result, the rotating magnet 1 is magnetically neutral without being pulled between the upper and lower first stators 5 and the second stator 6 sandwiched therebetween, so that the force applied to the bearing 3 is reduced. Since it is small, there is little friction loss even if the fitting diameter is large, and the electromagnetic force generated as a device can be effectively converted to rotational torque.

  Next, the operation of the magnet 1 by energizing the coil 4 will be briefly described.

  5 and 6 are top views as seen from the axial direction, and only the magnet 1, the drive pin 1h, and the first stator 5 are seen from the opposite side of FIG. 4 for easy understanding. . Specifically, FIG. 5 shows a state in which the magnet 1 is rotated counterclockwise by reverse energization of the coil 4 and the drive pin 1 h is in contact with the right side surface of the magnetic pole teeth 5 a of the first stator 5. FIG. 6 shows a state in which the magnet 1 is rotated clockwise by positive energization of the coil 4 and the drive pin 1 h is rotated in the direction of another magnetic pole tooth 5 a adjacent to the first stator 5.

  When the magnetic pole teeth of the first stator 5 (and the second stator 6 (not shown)) are excited by energizing the coil 4 (assuming positive energization), the generated magnet is sandwiched between the magnetic pole teeth 5a. An electromagnetic force that rotates the magnet 1 is generated by passing through one magnetized portion. As shown in FIG. 5, when the center of the magnetized portion 1a of the magnet 1 is shifted in the clockwise direction with respect to the center of the width of the magnetic pole tooth 5a (α ° in the drawing), the coil 4 is positively energized, Is excited to the N pole, the back surface of the magnetized portion 1a of the magnet 1 repels because it is the N pole, and the magnet 1 obtains a force that rotates clockwise. Even the other adjacent magnetic pole teeth 5a on the right side are attracted because the back surface of the magnetized portion 1b is the S pole, and the magnet 1 also becomes a force that rotates clockwise.

  As shown in FIG. 6, the coil 4 is reversely energized in a state where the center of the magnetized portion 1b of the magnet 1 is shifted counterclockwise with respect to the center of the width of another adjacent magnetic pole tooth 5a. When the magnetic pole teeth 5a are excited to the S pole, the back surface of the magnetized portion 1b of the magnet 1 repels because it is the S pole, and the magnet 1 obtains a force that rotates counterclockwise. Even the magnetic pole teeth 6a on the opposite side across the magnet 1 are attracted because the surface of the magnetized portion 1a is the S pole, and the magnet 1 also becomes a force that rotates counterclockwise.

  As described above, a reciprocating driving device is configured in which the magnet 1 rotates clockwise when the coil 4 is energized, and rotates counterclockwise when the energization is reversed. The rotation stroke is determined by the width of each magnetic pole tooth, the width of magnetization, and the rotation direction is also determined by which pole of the magnet 1 is arranged at a position where each magnetic pole tooth is located. The magnet 1 can be rotated clockwise or counterclockwise by electromagnetic force that repels if magnetized to the same pole as the excited pole and attracts if magnetized to a different pole. Therefore, if the drive pin 1h of the magnet 1 is interlocked with a light quantity adjusting device (not shown), for example, a shutter blade of the shutter device, the shutter of the shutter device is driven by the drive pin 1h that reciprocates in response to switching of the energization direction to the coil 4. Since the blades are opened and closed, a highly efficient and thin shutter device can be realized easily.

  Here, it will be described that the drive device, which is a step motor having the above-described configuration, has an optimum configuration for high output and ultra-miniaturization.

The basic configuration of the drive device according to the first embodiment will be described.
First, the magnet 1 is formed in a ring shape,
Second, one surface and the other surface in the direction perpendicular to the virtual axis that is the rotation center of the magnet 1 are divided into a plurality of portions in the circumferential direction and magnetized alternately to different poles;
Third, the coil 4 is coaxially arranged outside the outer peripheral surface of the magnet 1 (or inside the inner peripheral surface or both of them),
Fourth, each of the first stator 5 and the second stator 6 excited by the coil 4 is placed on a plane perpendicular to the virtual axis serving as the center of rotation of the ring-shaped magnet 1, that is, a ring-shaped plane. Facing each other,
Fifth, each magnetic pole tooth 5a, 6a of the first stator 5 and the second stator 6 is constituted by comb teeth extending in the radial direction,
Sixth, the sum ΣS11 of the overlapping areas seen from the axial direction of the magnet 1 and the first stator 5 and the sum ΣS12 of the overlapping areas seen from the axial direction of the magnet 1 and the second stator 6 are made equal to each other. The attraction forces F and F ′ generated between the upper and lower stators 5 and 6 are substantially equal, and the magnet 1 is made neutral.
It is.

  As described above, the rotating magnet 1 is magnetically neutral without being pulled by one between the magnetic pole teeth 5a and 6a sandwiched therebetween, and the force applied to the bearing 3 is small, so that the fitting diameter is large. Friction loss is small, and the electromagnetic force generated as a drive device can be effectively converted to rotational torque.

  Further, the magnetic flux generated by energizing the coil 4 effectively works because it crosses the magnet 1 between the first stator 5 and the second stator 6. In addition, since the first stator 5 and the second stator 6 are all configured in a comb-teeth shape extending in the radial direction, the dimensions in the axial direction are smaller than those configured in the axial direction. it can.

  As described above, it is possible to provide a thin and highly efficient driving device suitable for a light amount adjusting device such as a shutter device.

  Next, a second embodiment according to the present invention will be described with reference to FIGS. FIG. 7 is an exploded perspective view of the driving apparatus according to the second embodiment of the present invention. Here, unlike FIG. FIG. 8 is a view showing only the magnet 101 and the second stator 106 in the drive device of FIG. 7, and FIG. 9 is a sectional view of the drive device of FIG. 7 in an assembled state. Here, only the differences 101, 102, 103, and 106, which are different from the first embodiment, will be described, and the other 104 and 105 are the same as the coil 4 and the first stator 5 of the first embodiment, and the details thereof are described. Is omitted.

  In these drawings, reference numeral 101 denotes a ring-shaped magnet made of a plastic magnet material or the like, and one surface perpendicular to the virtual axis serving as the ring-shaped rotation center and the other surface are divided into 16 in the circumferential direction. It is alternately magnetized to S and N poles. In addition, each back surface is an opposite pole. In this example, the number of magnetic poles is 16 poles, but the magnet may be 2 poles or more. In order to output the rotational torque of the magnet 1, a drive pin 101h is formed on the second stator 106 described later.

  Reference numeral 102 denotes a ring that determines the positions in the radial direction and the axial direction. The ring 102 is joined to the magnet 101, and the inner periphery thereof is fitted to the outer periphery of the bearing 3 and smoothly rotates while maintaining the same axis. The material is very smooth and has good slidability. For example, plastic is made of polyacetal, Teflon (trademark), fluororesin, etc., so the first sliding surface 102a in the axial direction is made of metal. Smoothness is not lost even when sliding with the stator 105 and the second stator 106. Further, the distance D101 between the first stator 105 and the magnet 101 and the distance D102 between the second stator 106 and the magnet 101 depend on the height of the upper sliding surface 102a and the lower sliding surface 102a of the ring 102. The magnet 101 is joined to the ring 102 so as to be shifted upward in FIG. 9 so that the gap between the magnet and the stator important for torque generation is stably secured and the distance D102 is larger than the distance D101.

  Reference numeral 103 denotes a bearing, which smoothly smooths the ring 102 made of a material having smooth smoothness, such as polyacetal, Teflon (trademark), fluorine-based resin, etc., and integrated with the magnet 101 on the outer periphery. Rotate. Further, the step 103a is fitted and fixed while securing the same axis as the inner periphery of a connecting portion 106b of the second stator 106 described later. Reference numeral 106 denotes a second stator made of a soft magnetic material, which is excited by energizing the coil 104. The second stator 106 is opposed to a plane (the other surface) perpendicular to the axial direction of the ring-shaped magnet 101 with a predetermined gap, and is a flat comb-like shape extending in the radial direction of the magnet 101 and in the inner diameter direction. It is composed of magnetic pole teeth 106a, a connecting portion 106b into which the stepped portion 103a of the bearing 103 is fitted, and an upright portion 106j having a standing wall shape at the outermost peripheral portion. The fitting part 106b contributes to improving the position accuracy of the comb teeth by connecting the comb teeth group at the tip thereof.

  When the coil 104 is energized and the magnetic pole teeth 105a are excited to the north pole in the assembled state as in the first embodiment, the attractive force toward the center of the south pole of the magnet 101 toward the center of the magnetic pole teeth 105a. F is generated. However, since the magnet 101 is restrained by the ring 102 and the first stator 105 in the axial direction, the magnet 101 is divided into an axial force F1 and a rotational force F2. Similarly, when the magnetic pole teeth 106a are excited to the south pole, an attractive force F ′ is generated in which the central portion of the north pole of the magnet 101 is directed toward the center of the magnetic pole teeth 106a. Since it is restrained by the second stator 106, it is divided into an axial force F1 ′ and a rotational force F2 ′. Here, the smaller the distance D101 shown in FIG. 9 is, the larger the attractive force F generated between the first stator 105 and the magnet 101 is. Similarly, the smaller the distance D102 is, the smaller the distance D102 is. The attractive force F ′ generated between the magnets 101 increases.

  In the second embodiment, the sum ΣS102 of the overlapping area of the second stator 106 and the magnet 101 is larger by the portion of the connecting portion 106b than the sum ΣS101 of the overlapping area of the first stator 105 and the magnet 101 (see FIG. 8). . These are based on the results of electromagnetic analysis and experiment by the finite element method. According to this, if the distance D101 and the distance D102 are equal, the attractive force F ′ generated between the second stator 106 and the magnet 101 is reduced. Is larger than the attractive force F generated between the first stator 105 and the magnet 101, and as a result, the magnet 101 is attracted to the second stator 106 side, and the sliding surface 102a of the ring 102 is large. The force contacts the second stator 106, and the friction loss during rotation increases.

  In the second embodiment, since the sum of the overlapping areas is in a relationship of ΣS101 <ΣS102, the distance is in a relationship of D101 <D102 as shown in FIG. Are approximately equal, and the divided axial forces F1 and F1 ′ are also equal. Therefore, the rotating magnet 101 is magnetically neutral without being pulled between the upper and lower first stators 105 and the second stator 106 sandwiched therebetween, and the force applied to the sliding surface is reduced. Therefore, even if the fitting diameter is large, the friction loss is small, and the electromagnetic force generated as the drive device can be effectively converted to rotational torque.

The basic configuration of the drive device according to the second embodiment will be described.
First, the magnet 101 is formed in a ring shape,
Second, one surface and the other surface in the direction perpendicular to the virtual axis that is the rotation center of the magnet 101 are divided into a plurality of portions in the circumferential direction and are alternately magnetized to different poles.
Third, the coil 104 is coaxially disposed outside the outer peripheral surface of the magnet 101 (or inside the inner peripheral surface or both of them).
Fourth, each of the first stator 105 and the second stator 106 excited by the coil 104 is placed on a plane perpendicular to the virtual axis that is the center of rotation of the ring-shaped magnet 101, that is, a ring-shaped plane. Facing each other,
Fifth, each magnetic pole tooth 105a, 106a of the first stator 105 and the second stator 106 is constituted by comb teeth extending in the radial direction,
Sixth, the sum ΣS101 of the overlapping areas seen from the axial direction of the magnet 101 and the first stator 105 and the sum ΣS102 of the overlapping areas seen from the axial direction of the magnet 101 and the second stator 106 are in a relationship of ΣS101 <ΣS102. The attracting forces F and F ′ generated between the magnet 101 and the upper and lower stators 105 and 106 are approximately equal to make the magnet 101 neutral.
Seventh, the distance (gap) between the magnet 101 and the stator on the side where the overlapping area of the magnetic teeth of the upper or lower stators 105 and 106 and the magnet 101 is larger is set to be larger than the other.
Eighth, the ratio of the overlapping areas of each stator to each other is approximately equal to the square of each distance,
It is.

  As described above, the magnetic pole teeth between which the rotating magnet 101 is sandwiched are not pulled to one side, so that they are magnetically neutral. Therefore, the force applied to the bearing 103 is small, so even if the fitting diameter is large, the friction loss Therefore, the electromagnetic force generated as a drive device can be effectively converted to a rotational torque.

  Further, since the magnetic flux generated by energizing the coil 104 crosses the magnet 101 between the first stator 105 and the second stator 106, it acts effectively. Further, since the first stator 105 and the second stator 106 are all configured in a comb-teeth shape extending in the radial direction, the dimensions in the axial direction are smaller than those configured in the axial direction. it can.

  As described above, it is possible to provide a thin and highly efficient driving device suitable for a light amount adjusting device such as a shutter device.

  Next, a driving apparatus according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 10 is a cross-sectional view of the assembled drive device. Here, only the differences will be described in addition to the first and second embodiments, and the other description will be omitted.

  The magnet, ring, and coil, which are components of the driving device, are the same as the magnet 1, ring 2, and coil 4 of the first embodiment, and the bearing and the second stator are the bearing 103, second of the second embodiment. The same stator 106 is assumed. The only difference from the above embodiments is that the thickness of the first stator 205 is T1 (> T2) while the thickness of the second stator 106 in the axial direction is T2.

  As is clear from the description of the second embodiment, the sum ΣS201 of the overlapping areas of the first stator 205 and the magnet 1 and the sum ΣS202 of the overlapping areas of the second stator 106 and the magnet 1 are in a relationship of ΣS201 <Σ202. It is in. In FIG. 10, if the distance between the magnet 1 and the first stator 205 is D1, and the distance between the magnet 1 and the second stator 106 is D2, then D1≈D2, and therefore the first stator 205 for the following reason. Is made thicker than the plate thickness T2 of the second stator 206.

  As in FIG. 8, in the third embodiment, the sum ΣS202 of the overlapping area of the second stator 106 and the magnet 1 is greater than the sum ΣS201 of the overlapping area of the first stator 205 and the magnet 1. Only the portion 106b is large. When the distance D1 and the distance D2 are equal due to various factors, the attractive force F ′ generated between the second stator 106 and the magnet 1 is more than the attractive force F generated between the first stator 205 and the magnet 1. As a result, the magnet 1 is attracted to the second stator 106 side, the sliding surface 2a of the ring 2 comes into contact with the second stator 106 with a large force, and the friction loss during rotation increases. End up.

  These are based on the results of electromagnetic analysis and experiments by the finite element method. In the third embodiment, the sum of the overlapping areas is ΣS201 <ΣS202, and the distance is D1≈D2 as shown in FIG. In some cases, the relationship between the plate thickness T1 of the first stator 205 and the plate thickness T2 of the second stator 106 is T1> T2, so that the attractive forces F and F ′ are approximately equal to each other so that the force is divided. The axial forces F1 and F1 ′ are also equal. In this way, the upper and lower first stators 205 and the second stator 106 between which the rotating magnet 1 is sandwiched are magnetically neutral without being pulled to one side, and the sliding surface Since this force is small, there is little friction loss even if the fitting diameter is large, and the electromagnetic force generated as a drive device can be effectively converted to rotational torque.

The basic configuration of the drive device according to the third embodiment will be described.
First, the magnet 1 is formed in a ring shape,
Second, one surface and the other surface in the direction perpendicular to the virtual axis that is the rotation center of the magnet 1 are divided into a plurality of portions in the circumferential direction and magnetized alternately to different poles;
Third, the coil 4 is coaxially arranged outside the outer peripheral surface of the magnet 1 (or inside the inner peripheral surface or both of them),
Fourth, each of the first stator 205 and the second stator 106 excited by the coil 4 is placed on a plane perpendicular to the virtual axis serving as the center of rotation of the ring-shaped magnet 1, that is, a ring-shaped plane. Facing each other,
Fifth, each magnetic pole tooth 205a, 106a of the first stator 205 and the second stator 106 is constituted by comb teeth extending in the radial direction,
Sixth, the sum ΣS201 of the overlapping areas seen from the axial direction of the magnet 1 and the first stator 205 and the sum ΣS202 of the overlapping areas seen from the axial direction of the magnet 1 and the second stator 106 are in a relationship of ΣS201 <ΣS202. The attracting forces F and F ′ generated between the magnet 1 and the upper and lower stators 205 and 106 are approximately equal, and the magnet 1 is made neutral.
Seventh, if the distance is the same, the thickness of the stator on the side where the overlapping area of the magnetic pole teeth of the upper and lower stators 205 and 106 and the magnet 1 is larger is made thinner than the other.
It is.

  As described above, the rotating magnet 1 is magnetically neutral without being attracted to one of the sandwiched magnetic pole teeth, and therefore the force applied to the bearing is small, so that even if the fitting diameter is large, there is no friction loss. Therefore, the electromagnetic force generated as a device can be effectively converted to rotational torque.

  Further, since the magnetic flux generated by energizing the coil 4 crosses the magnet 1 between the first stator 205 and the second stator 106, it acts effectively. Since the first stator 205 and the second stator 106 are all configured in a comb-teeth shape extending in the radial direction, the dimensions in the axial direction can be made smaller than those configured in the axial direction.

  In addition to increasing the thickness of the stator, it goes without saying that the same effect can be obtained by arranging another magnetic body in the vicinity.

  As described above, it is possible to provide a thin and highly efficient driving device suitable for a light amount adjusting device such as a shutter device.

  Next, a driving apparatus according to Embodiment 4 of the present invention will be described with reference to FIGS. FIG. 11 is a sectional view of the assembled state of the drive device, and FIG. 12 shows the magnetic characteristics of the metal material used for each stator of the drive device.

  The magnets, rings, bearings, and coils that are components of the drive device are the same as the magnets 101, rings 102, bearings 103, and coils 104 of the second embodiment, and the shapes of the first stator and the second stator are the same. Is the same as the first stator 105 and the second stator 106 of the second embodiment, but only the material is changed.

  When the distance D101 between the first stator 105 and the magnet 101 is equal to the distance D102 between the second stator 106 and the magnet 101 due to various factors, the attractive force F ′ generated between the second stator 106 and the magnet 101 is greater. Becomes larger than the attractive force F generated between the first stator 105 and the magnet 101, and as a result, the magnet 101 is attracted to the second stator 106 side, and the sliding surface 102 a of the ring 102 has a large force. Thus, the second stator 106 is contacted, and the friction loss during rotation increases.

  Based on the results of electromagnetic analysis and experiments by the finite element method, in Example 4, the sum of the overlapping areas is ΣS101 <ΣS102, and the distance is D101≈D102 as shown in FIG. In FIG. 2, the first stator 105 and the second stator 106 are made of materials having different magnetic characteristics, so that the attractive forces F and F ′ are approximately equal. Specifically, by selecting a material that is advantageous for the maximum magnetic flux density among the magnetic characteristics, for example, the difference in the axial attractive force due to the difference in the overlapping area is eliminated.

  12 is selected as the material of the first stator 105, the maximum magnetic flux density is B1 = 1.05T, the 78% permalloy PC of FIG. 12 is selected as the material of the second stator 106, and the maximum magnetic flux density is selected. Assuming that B2 = 0.72T, when ΣS101 <ΣS102, B1> B2.

  As described above, for example, when a large current flows through the coil and each stator is excited to near the saturation point, the second stator 106 having a large area facing the magnet is quickly magnetically saturated, and the first stator 105 is magnetically saturated. Therefore, the suction forces F and F ′ can be made substantially equal, and the divided axial forces F1 and F1 ′ can also be made equal. Therefore, the upper and lower first stators 105 and the second stator 106 sandwiched by the rotating magnet 101 are not attracted to one side and become magnetically neutral, and the force applied to the sliding surface is reduced. Therefore, even if the fitting diameter is large, the friction loss is small, and the electromagnetic force generated as the drive device can be effectively converted to rotational torque.

The basic configuration of the drive device according to the fourth embodiment will be described.
First, the magnet 101 is formed in a ring shape,
Second, one surface and the other surface in the direction perpendicular to the virtual axis that is the rotation center of the magnet 101 are divided into a plurality of portions in the circumferential direction and are alternately magnetized to different poles.
Third, the coil 4 is coaxially arranged outside the outer peripheral surface of the magnet 101 (or inside the inner peripheral surface or both of them),
Fourth, each of the first stator 105 and the second stator 106 excited by the coil 104 is placed on a plane perpendicular to the virtual axis that is the center of rotation of the ring-shaped magnet 101, that is, a ring-shaped plane. Facing each other,
Fifth, each magnetic pole tooth of the first stator 105 and the second stator 106 is constituted by comb teeth extending in the radial direction,
Sixth, the sum ΣS101 of the overlapping areas seen from the axial direction of the magnet 101 and the first stator 105 and the sum ΣS102 of the overlapping areas seen from the axial direction of the magnet 1 and the second stator 106 are in a relationship of ΣS101 <ΣS102. The attracting forces F and F ′ generated between the magnet 101 and the upper and lower stators 105 and 106 are approximately equal to make the magnet 101 neutral.
Seventh, when the distance is the same, the materials of the upper and lower stators 105 and 106 are different, and the material of the stator on the side where the overlapping area of the magnetic pole teeth and the magnet 101 is smaller has higher saturation magnetization than the other, or , Using materials with magnetic properties of high permeability and strong attraction,
It is.

  As described above, the rotating magnet 101 is magnetically neutral without being attracted to one of the sandwiched magnetic pole teeth. Therefore, the force applied to the bearing is small, so that the friction loss is large even if the fitting diameter is large. Therefore, the electromagnetic force generated as a device can be effectively converted to rotational torque.

  As described above, it is possible to provide a thin and highly efficient driving device suitable for a light amount adjusting device such as a shutter device.

  Finally, the configurations and effects of the first embodiment without the first embodiment are listed below.

  1) In a drive device composed of upper and lower stators and coils facing each other with a magnet sandwiched from the axial direction, the suction force between the upper stator and the magnet and the lower stator are made equal to each other as much as possible in the axial direction. Loss in bearings can be reduced. As the means, by making the sum (sum) of the overlapping area of the upper and lower stators and magnets the same up and down, the magnet is neutral between the upper and lower stators, and the axial force applied to the bearing is reduced, Friction loss generated by the bearing can be reduced, and a highly efficient, thin, and inexpensive drive device can be configured.

  2) Also, if there is a difference in the sum of the overlapping areas of the upper and lower stators and the magnet, the distance (gap) between the stator and magnet on the side with the larger sum of the areas is set to the smaller of the sum of the overlapping areas. By making it narrower than the gap, the above condition is satisfied. That is, the overlapping area of the first stator and the magnetized portion of the magnet as viewed from the axial direction is S1, the sum over the entire circumference is ΣS1, and the overlapping of the second stator and the magnetized portion of the magnet as viewed from the axial direction. The area S2, the sum over the entire circumference is ΣS2, the axial distance between the first stator and the magnet is D1, the axial distance between the second stator and the magnet is D2, and when ΣS1 <ΣS2, D1 <D2 As a result, the magnet is neutral between the upper and lower stators, the axial force applied to the bearing is reduced, and the friction loss generated by the bearing can be reduced.

  3) In addition, the overlapping area of the magnetized portions of the first stator and the magnet viewed from the axial direction is S1, the total over the entire circumference is ΣS1, the plate thickness of the first stator is T1, and the first stator and the magnet The axial distance is D1, the overlapping area S2 of the magnetized portion of the second stator and the magnet viewed from the axial direction, ΣS2 is the sum over the entire circumference, and the plate thickness of the second magnetic pole is T2. The axial distance between the second stator and the magnet is D2, and when ΣS1 <ΣS2 and D1≈D2, the relationship of T1> T2 is established so that the magnet is neutral between the upper and lower stators and is applied to the bearing. The axial force is reduced and the friction loss caused by the bearing can be reduced, and a highly efficient, thin and inexpensive drive device can be configured.

  4) The axial distance between the first stator and the magnet is D1, the axial distance between the second stator and the magnet is D2, and the overlapping area of the magnetized portions of the first stator and the magnet when viewed from the axial direction is S1, the sum total over the entire circumference is ΣS1, the overlapping area S2 of the magnetized portion of the second stator and the magnet when viewed from the axial direction, and the sum over the entire circumference is ΣS2, if ΣS1 and ΣS2 are different, By using materials with different magnetic characteristics for the first stator and the second stator, even when there is a difference in the sum of the overlapping areas of the upper and lower stators and the magnets, Loss is reduced by almost eliminating such force. The magnetic characteristics are mainly the saturation magnetization and permeability of the metal. This neutralizes the magnet between the upper and lower stators, reducing the axial force applied to the bearing, and reducing the friction loss caused by the bearing, making it a highly efficient, thin and inexpensive drive device can do.

It is a disassembled perspective view of the drive device concerning Example 1 of this invention. It is the elements on larger scale of the assembly completion state of the drive device of FIG. It is sectional drawing of the assembly completion state of the drive device of FIG. FIG. 2 is a top view showing only a magnet 1 and a first stator in the drive device of FIG. 1. It is operation | movement explanatory drawing of the drive device of FIG. 1 which showed only the magnet 1 and the 1st stator 5. FIG. It is operation | movement explanatory drawing of the drive device of FIG. 1 which showed only the magnet 1 and the 1st stator 5. FIG. It is a disassembled perspective view of the drive device concerning Example 2 of this invention. FIG. 8 is a top view showing only a magnet and a second stator of the drive device of FIG. 7. It is sectional drawing of the assembly state of the drive device of FIG. It is sectional drawing of the assembly state of the drive device concerning Example 3 of this invention. It is sectional drawing of the assembly state of the drive device concerning Example 4 of this invention. It is a figure which shows the magnetic characteristic of the steel plate material of the stator with which the drive device concerning Example 4 of this invention is equipped. It is sectional drawing which shows an example of the conventional stepping motor. It is a perspective view which shows an example of the conventional stepping motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnet 2 Ring 3 Bearing 4 Coil 5 1st stator 5a Magnetic pole tooth 6 Second stator 6a Magnetic pole tooth 101 Magnet 102 Ring 103 Bearing 104 Coil 105 First stator 105a Magnetic pole tooth 106 Second stator 106a Magnetic pole tooth 106b Connection Part 205 first stator

Claims (6)

A ring-shaped magnet that is divided into multiple pieces in the circumferential direction and alternately magnetized to different poles;
A bearing for rotatably holding the ring-shaped magnet with its center as a virtual axis;
A coil disposed on the outside of the outside diameter of the magnet or on the inside of the inside diameter or on the outside of the outside diameter and the inside of the inside diameter;
A first stator that is disposed opposite one surface in a direction perpendicular to the axis that is the rotation center of the magnet and is excited by the coil;
In a drive device having a second stator that is disposed opposite to the other surface in the direction perpendicular to the axis that is the rotation center of the magnet and is excited by the coil,
The overlapping area of the magnetized portions of the first stator and the magnet viewed from the axial direction is S1, the sum over the entire circumference is ΣS1, and the second stator and the magnet are magnetized from the axial direction. The overlapping area S2, the total over the entire circumference is ΣS2, the axial distance between the first stator and the magnet is D1, and the distance between the second stator and the magnet in the virtual axis direction is D2. ,
When ΣS1 = ΣS2, the drive device is characterized in that the relationship between D1 and D2 is D1 = D2. A ring-shaped magnet that is divided into multiple pieces in the circumferential direction and alternately magnetized to different poles;
A bearing for rotatably holding the ring-shaped magnet with its center as a virtual axis;
A coil disposed on the outside of the outside diameter of the magnet or on the inside of the inside diameter or on the outside of the outside diameter and the inside of the inside diameter;
A first stator that is disposed opposite one surface in a direction perpendicular to the axis that is the rotation center of the magnet and is excited by the coil;
In a drive device having a second stator that is disposed opposite to the other surface in the direction perpendicular to the axis that is the rotation center of the magnet and is excited by the coil,
The overlapping area of the magnetized portions of the first stator and the magnet viewed from the axial direction is S1, the sum over the entire circumference is ΣS1, and the second stator and the magnet are magnetized from the axial direction. The overlapping area S2, the total over the entire circumference is ΣS2, the axial distance between the first stator and the magnet is D1, and the distance between the second stator and the magnet in the virtual axis direction is D2. ,
When ΣS1 <ΣS2, the relationship between the D1 and the D2 is D1 <D2. A ring-shaped magnet that is divided into multiple pieces in the circumferential direction and alternately magnetized to different poles;
A bearing for rotatably holding the ring-shaped magnet with its center as a virtual axis;
A coil disposed on the outside of the outside diameter of the magnet or on the inside of the inside diameter or on the outside of the outside diameter and the inside of the inside diameter;
A first stator that is disposed opposite one surface in a direction perpendicular to the axis that is the rotation center of the magnet and is excited by the coil;
In a drive device having a second stator that is disposed opposite to the other surface in the direction perpendicular to the axis that is the rotation center of the magnet and is excited by the coil,
The overlapping area of the magnetized portion of the first stator and the magnet viewed from the axial direction is S1, the total over the entire circumference is ΣS1, the axial thickness of the first stator is T1, the first The distance in the axial direction between the first stator and the magnet is D1, the overlapping area S2 of the magnetized portion of the second stator and the magnet viewed from the axial direction, the sum over the entire circumference is ΣS2, and the second The axial plate thickness of the magnetic pole part is T2, and the distance between the second stator and the magnet in the virtual axis direction is D2,
A drive device characterized in that when ΣS1 <ΣS2 and D1≈D2, the relationship between T1 and T1 is T1> T2. A ring-shaped magnet that is divided into multiple pieces in the circumferential direction and alternately magnetized to different poles;
A bearing for rotatably holding the ring-shaped magnet with its center as a virtual axis;
A coil disposed on the outside of the outside diameter of the magnet or on the inside of the inside diameter or on the outside of the outside diameter and the inside of the inside diameter;
A first stator that is disposed opposite one surface in a direction perpendicular to the axis that is the rotation center of the magnet and is excited by the coil;
In a drive device having a second stator that is disposed opposite to the other surface in the direction perpendicular to the axis that is the rotation center of the magnet and is excited by the coil,
The overlapping area of the magnetized portion of the first stator and the magnet seen from the axial direction is S1, the sum over the entire circumference is ΣS1, and the summed area of the second stator and the magnet seen from the axial direction is When ΣS2 is the sum of the overlapping area S2 and the total circumference thereof, if ΣS1 and ΣS2 are different, the first stator and the second stator are made of materials having different magnetic characteristics, so that the magnet and the second stator are used. 1. A driving device characterized in that the electromagnetic force acting between the first and second stators is made equal. The axial distance between the first stator and the magnet is D1, the material saturation magnetization B1, the axial distance between the second stator and the magnet is D2, and the saturation magnetization of the material is B2. When D1 = D2 and ΣS1 <ΣS2,
5. The driving device according to claim 4, wherein the first stator and the second stator are made of a material such that a relationship between B <b> 1 and B <b> 2 satisfies B <b>1> B <b> 2. 6. A light amount adjusting device comprising: the driving device according to claim 1; and a light amount adjusting member that is driven by the driving device and performs light amount adjustment.

Images