JP2004064899A - Drive unit and light volume adjusting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To convert energy generated by exciting an outer magnetic pole to a rotative force as much as possible by minimizing the generation of an absorption force between a magnet and the outer magnetic pole, and to obtain smooth rotation with a high output even by small power. <P>SOLUTION: A stator is provided comprising a rotor 101 having the magnet, a coil 102 and tooth-shaped outer magnetic poles 104a, 104b and an inner magnetic pole 104c, and the outer magnetic poles opposing the external peripheral surface of the magnet are arranged so as to oppose the external peripheral surface of the magnet at a prescribed angle or within the range of the angle. When the ratio of the prescribed angle at which the outer magnetic pole opposes the magnet and an angle per magnetized pole of the magnet is set as Y, and the value of the ratio of the a circumferential length per magnetized pole of the magnet to the radial thickness of the magnet is set as X, a relation of -0.3X + 0.72 ≤ Y ≤ -0.3 + 0.63 is satisfied. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a driving device suitable as a driving source for a camera or the like and an improvement of a light amount adjusting device including the driving device.
[0002]
[Prior art]
FIG. 17 shows a conventional light amount adjusting device for a lens shutter camera.
[0003]
In the figure, 201 is a permanent magnet, 202 is a drive lever, and 202a is a drive pin provided on the drive lever 202. The drive lever 202 is fixed to the permanent magnet 201 and rotates integrally with the permanent magnet 201. 203 is a coil, and 204 and 205 are stators made of a soft magnetic material and excited by the coil 203. The stator 204 and the stator 205 are joined at a portion 204a and a portion 205a, and are integrated on a magnetic circuit. When the coil 203 is energized, the stator 204 and the stator 205 are excited, and the permanent magnet 201 is driven to rotate within a predetermined angle. Reference numerals 206 and 207 denote shutter blades, and reference numeral 208 denotes a main plate. The shutter blades 206 and 207 are rotatably attached to pins 208a and 208b of the main plate 208 at holes 206a and 207a, and the elongated holes 206b and 207b are slidably fitted to the drive pins 202a. When the drive lever 202 rotates, the shutter blades 206 and 207 are driven to rotate around the holes 206a and 207a, and open and close an opening (not shown).
[0004]
As another form, a permanent magnet is formed of a plastic magnet to prevent cost increase, and a drive pin is integrally formed.
[0005]
Reference numeral 209 denotes a front base plate that movably holds the shutter blades 206, 207 between the base plate 208, and reference numeral 120 denotes a rear base plate that holds the stators 204, 205 and rotatably holds the permanent magnet 201. is there.
[0006]
The above-described light amount adjusting device has a disadvantage that the coil and the stator occupy a large area on the main plate, and it is difficult to arrange other actuators, lens guide bars, and the like. In view of this point, the present applicant has proposed the following light amount adjusting device in Japanese Patent Application Laid-Open No. 2002-49076.
[0007]
At least the outer peripheral surface is divided in the circumferential direction and is alternately magnetized to different poles, provided with a magnet rotatable about a rotation center, a coil arranged in the axial direction of the magnet, and an outer magnetic pole excited by the coil A drive device comprising a stator and a blade drive pin integrally formed with the magnet, wherein the stator and the inner magnetic pole portion face the outer peripheral surface and the inner peripheral surface of the magnet; a base plate having an opening; A light amount adjusting device including a light amount adjusting blade driven by a blade driving pin to adjust an opening amount of an opening of the ground plate.
[0008]
With the light amount adjusting device having such a configuration, the coil and the magnet are arranged in the axial direction, so that they have a large effect, such as a compact device that does not occupy a large area on the base plate. .
[0009]
[Problems to be solved by the invention]
By the way, when the light amount adjusting blade of the camera is driven by using the light amount adjusting device having such a configuration, when the coil is not energized, the magnet is attracted to the outer magnetic pole portion (cogging force) to stabilize the magnet. It has been found that the position of the shutter blade is halfway through the maximum opening of the shutter blade and in the closed opening process where light is completely shielded.
[0010]
When the camera is a digital camera, the object image is photoelectrically converted and recorded in a storage medium such as a CCD, so that the image is not exposed when the power is not turned on. There is no problem in any position. On the other hand, in the case of a silver halide camera using a film as a recording medium, when the camera is turned off and the camera is not used, that is, when the coil is not energized, the light amount adjusting blade is moved to the opening so that unnecessary exposure is not performed. It must be held in a completely covered position (closed state). Therefore, it is conceivable that the light amount adjusting blade is held in the closed state by the urging means when the coil is not energized.
[0011]
However, if the cogging force is strong, the closed state cannot be stably maintained when no power is supplied unless the urging force of the urging means is increased. However, if the urging force of the urging means is increased, there is a problem in that the opening characteristic when the coil is energized in order to bring the light quantity adjusting blade into the maximum open state deteriorates.
[0012]
When a driving device having the above-described cogging force is used as a stepping motor, the energy (drive torque generated by energization) generated when the outer magnetic pole portion is excited is converted into the cogging force (cogging torque). The problem is that high power is required for smooth rotation.
[0013]
(Object of the invention)
A first object of the present invention is to minimize the generation of an attractive force between a magnet portion and an outer magnetic pole portion, and to convert a large amount of energy generated when the outer magnetic pole portion is excited into a rotating force. It is an object of the present invention to provide a driving device capable of performing smooth rotation with high output and low power.
[0014]
A second object of the present invention is to provide a light amount adjusting device capable of minimizing the generation of an attractive force between a magnet part and an outer magnetic pole part and making the movement of a light amount adjusting member smooth even with a small power. It is intended to provide.
[0015]
A third object of the present invention is to make it possible to reduce the urging force of the urging means, and to set the light quantity adjusting member in a desired opening state against the urging force of the urging means with a small amount of power when energized. It is an object of the present invention to provide a light-amount adjusting device that can operate the light-amount adjusting member to an initial state by the urging means when no power is supplied, and can stably maintain the state.
[0016]
[Means for Solving the Problems]
In order to achieve the first object, the invention according to claim 1 has a cylindrical magnet portion having an outer peripheral surface divided in a circumferential direction and alternately magnetized to different poles, and a rotation center is set on an axis. A rotatable rotor, a coil disposed in the axial direction of the rotor, and at least one tooth-shaped outer magnetic pole part and an inner magnetic pole part, wherein the outer magnetic pole part and the inner magnetic pole part are formed on the outer periphery of the magnet part. In a driving device having a stator opposed to a surface and an inner peripheral surface and excited by the coil, the tooth-shaped outer magnetic pole portion facing the outer peripheral surface of the magnet portion has a predetermined angle with respect to the outer peripheral surface of the magnet portion. Y is a ratio of the predetermined angle facing the magnet portion of the outer magnetic pole portion to the angle per magnetized pole of the magnet portion, and Thickness The value of the ratio of the length of the circumference of the per pole which are magnetized in the magnet unit when the X against
−0.3X + 0.72 ≦ Y ≦ −0.3X + 0.63
The driving device is set so as to satisfy the following condition.
[0017]
In order to achieve the second object, the invention according to claim 2 has a cylindrical magnet portion in which an outer peripheral surface is divided in a circumferential direction and alternately magnetized to different poles, and a rotation center is provided. A rotor rotatable around an axis, a coil arranged in the axial direction of the rotor, and at least one tooth-shaped outer magnetic pole part and an inner magnetic pole part, wherein the outer magnetic pole part and the inner magnetic pole part are the magnet part. A driving device having a stator which is opposed to the outer peripheral surface and the inner peripheral surface and is excited by the coil, and which operates with the rotation of the rotor which is a component of the driving device to adjust the opening amount of the opening. A light amount adjusting member having a light amount adjusting member, wherein the tooth-shaped outer magnetic pole portion facing the outer peripheral surface of the magnet portion faces a predetermined angle range of the outer peripheral surface of the magnet portion, and In front of the department The ratio of the predetermined angle facing the magnet portion to the angle per magnetized pole of the magnet portion is Y, and the circle per magnetized pole of the magnet portion relative to the radial thickness of the magnet portion. Assuming that the value of the length ratio on the circumference is X
−0.3X + 0.72 ≦ Y ≦ −0.3X + 0.63
The light amount adjusting device is set so as to satisfy the condition (1).
[0018]
In order to achieve the third object, the invention according to claim 3 is configured such that the rotor adjusts the light amount so that the light amount adjusting member opens the opening at a predetermined state when the coil is not energized. A light amount adjusting device according to claim 2, further comprising an urging means for urging.
[0019]
Similarly, in order to achieve the third object, the invention according to claim 4 is configured such that, when no current is supplied to the coil, the light amount adjusting member brings the opening into a closed state in which the opening is completely closed. A light amount adjusting device according to claim 2, further comprising an urging means for urging the rotor.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail based on illustrated embodiments.
[0021]
(First embodiment)
FIG. 1 is an exploded perspective view of a driving device according to a first embodiment of the present invention and a light amount adjusting device including the driving device, and FIG. 2 is a perspective view of an assembled state of the driving device and the like in FIG. FIG. 3 is a cross section of the left half of FIG. 2 where the outer magnetic pole portion exists, and the right half of FIG. 2 is a cross section where the outer magnetic pole portion does not exist. FIG. 4 is a sectional view taken along line BB of FIG. 3 when the opening of the light quantity adjusting blade is closed, and FIG. 5 is a sectional view taken along line BB of FIG. 3 when the opening of the light quantity adjusting blade is opened.
[0022]
In these figures, reference numeral 101 denotes a cylindrical magnet made of a plastic magnet material, the outer peripheral surface of which is divided into four parts in the circumferential direction and magnetized alternately with S and N poles. More specifically, as shown in FIG. 17, the outer peripheral surfaces of the magnetized portions 101a and 101c are magnetized to the N pole, and the outer peripheral surfaces of the magnetized portions 101b and 101d are magnetized to the S pole. In this example, the number of magnetized poles is four, but any number of poles may be used as long as the number is two or more.
[0023]
Reference numeral 102 denotes a cylindrical coil wound around the bobbin 3 having an insulating shape. The coil 2 is arranged concentrically with the magnet 101 and at a position overlapping the magnet 101 in the rotation axis direction. The outer diameter of the coil 102 is substantially the same as the outer diameter of the magnet portion of the magnet 101.
[0024]
Reference numeral 104 denotes a stator made of a soft magnetic material. The stator 104 includes an outer tube having tooth-shaped outer magnetic pole portions 104a and 104b formed at a tip end thereof, and an inner tube 4c as a cylindrical inner magnetic pole portion. The outer magnetic pole portions 104a and 104b are configured to face a predetermined angle (A degree in FIG. 4) with a predetermined gap from the outer peripheral surface of the magnet 101. The predetermined angle in the second embodiment will be described later. The inner magnetic pole portion 104c also faces the inner peripheral surface of the magnet 101 with a predetermined gap. The outer cylinder 104d of the stator 104 is fitted to an inner peripheral surface 107a of a cover 107 described later, and is fixed here.
[0025]
The magnet 101 is integrally formed with a pin 101g extending in the rotation axis direction. The pin 101g is rotatable in a later-described stopper groove 105b.
[0026]
105 is a main plate. As shown in FIG. 3, the shaft part 101e of the magnet 101 is rotatably fitted in the hole 105a of the base plate 105, and the shaft part 101f is rotatable in the hole 104e of the inner magnetic pole part of the stator 104. It is attached to fit. Further, the outer peripheral surface 105c of the main plate 105 is fitted to an inner peripheral surface 107a of a cover 107 described later, and is fixed thereto.
[0027]
Reference numeral 106 denotes a light amount adjusting blade which is driven by the rotation of the magnet 101 and can cover an exposure opening (not shown). The light amount adjusting blade 106 is fixed to a surface 1h in a direction perpendicular to the rotation axis of the magnet 101 by bonding or the like. Holes 106a and 106b are provided for phase matching with the magnet 101, the hole 106a fits with the shaft 101e of the magnet 101, and the hole 106b fits with the pin 1g of the magnet 101. I have. The light-amount adjusting blade 106 is fixed at a position where a portion that protrudes from the driving device when bonded to the magnet 101 does not contact the outer magnetic pole portion of the stator 104. In response to the rotation of the magnet 101, the light amount adjusting blade 106 moves to a position where the opening is closed and a position where the opening is opened.
[0028]
Reference numeral 107 denotes a cover disposed on the outer peripheral portion of the stator 104 to cover the components 101 to 106 and to make the axis of the shaft hole 104e of the stator 104 coincide with the axis of the shaft hole 105a of the main plate 105. . This is because the stator 104 and the main plate 105 are fitted and fixed on the inner peripheral surface 107a of the cover 107.
[0029]
Reference numeral 108 denotes a torsion coil spring which is an example of an urging means for urging the magnet 101 in a predetermined direction. The torsion coil spring 108 has a coil diameter D2 larger than the diameter D1 of the cover 107, and its end 108a is connected to a pin of the magnet 101. It is hooked on 101g. The opposite end 108b of the torsion coil spring 108 is hooked on the cut 107b of the cover 107. The biasing force of the torsion coil spring 108 is set to be greater than the strength with which the magnet 101 is held at a predetermined position when the coil 102 is not energized, that is, the cogging force.
[0030]
In the first embodiment of the present invention, a light amount adjusting device in which a mounting position of a driving device can be freely set is actually mounted on a base plate of a light amount adjusting device having an opening for defining the maximum exposure at the center. In other words, the light amount adjusting blade 106 can be moved between a closed position covering the opening of the main plate of the light amount adjusting device to be originally attached and an open position retracted from the opening. In this example, since the unit is a unit that can be freely attached to the ground plate of the light amount adjusting device, the description of the ground plate having an opening is omitted.
[0031]
The rotational position of the magnet 101 in FIG. 4 is a state in which the light amount adjusting blade 106 completely closes the opening (not shown) (closed state), and the rotational position of the magnet 101 in FIG. It is in a more retracted open state.
[0032]
When the coil 102 is energized from the state of FIG. 4 to excite the outer magnetic pole portions 104a and 104b of the stator 104 to the S pole and the inner magnetic pole portion 104c to the N pole, the magnet 101 rotates clockwise. State shown. In this state, the coil 102 is energized in the opposite direction to excite the outer magnetic pole portions 104a and 104b of the stator 104 to the N pole and the inner magnetic pole portion 104c to the S pole. It rotates to the state shown in FIG. The torsion coil spring 108 is urged in the direction of the arrow in FIG. 2 so that the state shown in FIG.
[0033]
Since the magnet 101 is formed of a plastic magnet material, and the shaft portions 101e and 101f and the pin 101g are integrally formed, the cost is lower and the assembly error is reduced as compared with the case where the magnet 101 is formed by separate parts. Further, since the outer magnetic pole portions 104a and 104b and the pin 1g of the magnet 101 can be arranged at positions overlapping in the axial direction of the magnet 101, the axial length of the substantially cylindrical actuator can be reduced.
[0034]
In the above configuration, since the coil 102 is arranged in the axial direction with the magnet 101, the actuator becomes a very compact actuator with respect to the diameter of the driving device. Further, since the outer magnetic pole portion and the inner magnetic pole portion facing the outer peripheral surface and the inner peripheral surface of the magnet 101 form a magnetic path sandwiching the magnet 101, the magnetic resistance is small. Further, since the lines of magnetic force generated by the coil 102 effectively act on the magnet 101, the actuator becomes a high-output actuator. As a result, a compact light amount adjusting device having stable operation characteristics can be obtained.
[0035]
Since the outer magnetic pole portions 104a and 104b of the stator 104 are formed in a comb shape extending in a direction parallel to the axial direction of the magnet 101, the diameter of the stator 104 is equal to the diameter of the magnet portion of the magnet 101. The size can be reduced to the minimum size including its own thickness, and a very small actuator can be obtained.
[0036]
Next, the shapes of the outer magnetic pole portions 104a and 104b will be described in detail. However, a detailed description will be given of a drive device in a state where the magnet 101 is not biased by a biasing means (in this example, a torsion coil spring 108).
[0037]
The magnet 101 is set so that the force with which the magnet 101 is attracted to the outer magnetic pole portions 104a and 104b is minimized. This will be described with reference to FIGS.
[0038]
6, the vertical axis indicates the torque generated between the outer magnetic pole portions 104a and 104b acting on the magnet 101 and the inner magnetic pole portion 104c and the torque generated when the coil 102 is energized, and the horizontal axis indicates the magnet 101. FIG.
[0039]
At points indicated by points E1 and E2, a negative force acts to return to the original position when trying to rotate forward, and a positive force acts to return to the original position when trying to reversely rotate. In other words, it is a cogging position at which the magnet 101 is stably positioned at the point E1 or E2 by the magnetic force between the magnet and the outer magnetic pole portion. Points F1, F2, and F3 are stop positions in an unstable equilibrium state in which a rotating force acts on the front and rear points E1 and E2 when the phase of the magnet is slightly deviated. If no current is supplied to the coil 102 and there is no urging by the urging means, it stops at the position of the point E1 or E2.
[0040]
Cogging stable points such as points E1 and E2 exist at a period of (360 / n) degrees when the number of magnetized poles of the magnet is n, and intermediate points thereof are unstable points such as points F1, F2 and F3. become.
[0041]
As a result of the numerical simulation by the finite element method, the angle of the magnetized pole and the angle of the outer magnetic pole portion facing the magnet (the angle of the outer magnetic pole portions 104a and 104b facing the magnet is indicated by A in FIG. 4). From the relationship, it has been clarified that the state of the attracted state between the outer magnetic pole portion and the magnet changes when the coil is not energized. According to this, the cogging position of the magnet changes depending on the angle facing the outer magnetic pole portion and the magnet. That is, when the angle of the outer magnetic pole portion facing the magnet is equal to or smaller than a predetermined value, the center of the pole of the magnet is stably held at a position facing the center of the outer magnetic pole portion. That is, the points E1 and E2 described in FIG. 6 are in this state. Conversely, when the angle of the outer magnetic pole portion facing the magnet exceeds a predetermined value, the boundary between the poles of the magnet is stably held at a position facing the center of the outer magnetic pole portion. These are the points E1 and E2 described in 6. This will be described with reference to FIG.
[0042]
FIG. 7 is a diagram illustrating the relationship between the width dimension of the outer magnetic pole portion, the cogging torque, and the magnet dimension.
[0043]
In FIG. 7, the horizontal axis is “magnet thickness / peripheral length per magnet pole”, and the horizontal axis is “facing angle facing magnet per outer magnetic pole portion / angle per magnet pole”.
[0044]
For example, when the outer diameter of the magnet is 10 mm, the inner diameter is 9 mm, and the number of poles is 16, the thickness of the magnet is “(10−9) / 2”, and the outer peripheral length per magnetized pole is Since it is “10 × π / 16”, the value of “magnet thickness / peripheral length per magnet pole” on the horizontal axis is 0.255. Also, if the angle of facing the magnet per one outer magnetic pole portion is 13 degrees, the angle per magnet of the magnetic pole is 22.5 degrees. The "angle per magnet pole" is 0.578.
[0045]
Each point in FIG. 7 is a plot of “facing angle to magnet per one outer magnetic pole portion / angle per magnet pole” of a model in which the cogging torque is almost zero or minimum. 8 is a graph showing a case where the cogging torque is substantially zero or minimum for the nine types of motors shown in FIG.
[0046]
The vertical axis of FIG. 7 is defined as “Y = facing angle to magnet per outer magnetic pole portion / angle per magnet” and the horizontal axis is “X = thickness of magnet / peripheral length per magnet”. , These points exist in a region surrounded by a straight line 1 approximated by the equation of “Y = −0.3X + 0.63” and a straight line 2 approximated by the equation of “Y = −0.3X + 0.72”. .
[0047]
The range below the straight line 1 in the figure, that is, the range of “Y <−0.3X + 0.63” is stably held at the position where the center of the magnet pole faces the center of the outer magnetic pole portion, and the range above the straight line 2 In other words, if “Y> −0.3X + 0.72”, the boundary between the poles of the magnet is stably held at a position facing the center of the outer magnetic pole portion. In a region surrounded by the straight line 1 and the straight line 2, that is, “−0.3X−0.72 ≦ Y ≦ −0.3X + 0.63”, the cogging torque becomes almost zero or extremely small.
[0048]
Here, the respective opposing angles A degrees of the outer magnetic pole portions 104a and 104b opposing the magnet 101 in the axial direction are average opposing angles if the angle gradually changes depending on the position of the magnet 101 in the rotation axis direction. Should satisfy the above conditional expression. In other words, even if the respective opposing angles near the end face of the magnet 101 are somewhat large, if the opposing angles of the front end, that is, the outer magnetic pole portions 104a and 104b near the center of the rotating shaft of the magnet 101 with respect to the magnet 101 are smaller, the respective angles are smaller. May be applied to the above conditional expression.
[0049]
9, 10, and 11 show experimental results.
[0050]
9, 10, and 11, as in FIG. 6, the horizontal axis indicates the torque due to the magnetic force generated between the outer magnetic pole portion and the inner magnetic pole portion acting on the magnet 101, and the horizontal axis indicates the rotational phase of the magnet 101. Is shown. The figure shows the torque when the coil is not energized, that is, the cogging torque and the torque generated when a voltage of 3 V is applied between the coil terminals.
[0051]
This model
・ The magnet has an outer diameter of 10.6 mm, an inner diameter of 9.8 mm, and 16 magnetized poles
・ The coil has 112 turns and a resistance of 10Ω
The outer magnetic pole portion of the stator has an outer diameter of φ11.6 mm and an inner diameter of 11.1 mm
・ The inner magnetic pole portion of the stator has an outer diameter of 9.3 mm and an inner diameter of 8.8 mm
Is a cylindrical configuration.
[0052]
In FIG. 9, each of the opposite angles A of the outer magnetic pole portion with respect to the magnet is 10.35 degrees. The values of X and Y are X = 0.192 and Y = 0.46.
[0053]
FIG. 10 shows the case where the opposite angle A degrees of the outer magnetic pole portion with respect to the magnet is 13.45 degrees. In this case, the torque generated when no current is supplied, that is, the coking torque, is the smallest. The values of X and Y are X = 0.192 and Y = 0.60.
[0054]
FIG. 11 shows that each of the opposite angles A of the outer magnetic pole portion with respect to the magnet is 15.52 degrees. The values of X and Y are X = 0.192 and Y = 0.69.
[0055]
FIG. 25 shows the results of FIG. 9, FIG. 10, and FIG. 11 superimposed on the straight line obtained in FIG.
[0056]
In the configuration whose characteristics are shown in FIG. 9, that is, the configuration in which the outer magnetic pole portion has an angle A of 10.35 degrees with respect to the magnet, X = 0.192, Y = 0.46, and "Y <-0. 3X + 0.63 ", and the stable position of the magnet was a position where the center of the pole of the magnetized portion was opposed to the center of the outer magnetic pole portion.
[0057]
In the configuration shown in FIG. 10, that is, the configuration in which the outer magnetic pole portion has an angle A of 13.45 degrees with respect to the magnet, X = 0.192, Y = 0.60, and “−0.3X + 0. 63 ≦ Y ≦ −0.3X + 0.72 ”, and the coking torque is extremely small.
[0058]
In the configuration whose characteristics are shown in FIG. 11, that is, the configuration in which the outer magnetic pole portion has an angle A of 15.52 degrees with respect to the magnet, X = 0.192, Y = 0.69 and "Y> -0. 3X + 0.72 ”, and the stable position of the magnet was a position where the boundary between the poles of the magnetized portion was opposed to the center of the outer magnetic pole portion.
[0059]
In the first embodiment, the dimension is set so as to satisfy “−0.3X + 0.72 ≦ Y ≦ −0.3X + 0.63”, and the cogging force may not stop at a predetermined position. For example, when the center of the pole of the magnetized portion of the magnet 101 is stopped at a position facing the center of the outer magnetic pole portion, even if the coil 102 is energized from this state to excite the outer magnetic pole portion 104a, No rotational force is generated.
[0060]
Therefore, in the first embodiment, the relationship between the stopper groove 105b of the base plate 105 and the pin 1g of the magnet 101 is configured as follows.
[0061]
As shown in FIG. 4, the rotational position of the magnet 101 is brought into contact with the end face of the stopper groove 105b, and the magnet pole of the magnet 101, that is, the center Q1 of the magnetized portion 101b and the center R1 of the outer magnetic pole portion 104a of the stator 104 are fixed. Is set to be α degrees. Thus, when the coil 102 is energized from the state of FIG. 4 to excite the outer magnetic pole portions 104a and 104b to the S pole, a clockwise rotational force is generated in the magnet 101, and the magnet 101 is started stably. State shown.
[0062]
Similarly, regarding the clockwise rotation of the magnet 101, in the second embodiment, the end face of the stopper groove 105b of the base plate 105 is brought into contact with the pin 1g of the magnet 101 so as to be at the position shown in FIG. It has been set. In this case, the position of the magnet 101 is set such that the angle formed between the pole of the magnet 101, that is, the center Q2 of the magnetized portion 1a and the center R1 of the outer magnetic pole portions 104a and 104b becomes β degrees. As a result, when the coil 102 is energized from the state of FIG. 5 to excite the outer magnetic pole portions 104a and 104b to the N pole, a counterclockwise rotating force is generated in the magnet 101, and the magnet 101 is driven stably. State.
[0063]
When the state of FIG. 5 is applied to FIG. 6, the position of point H is obtained. The cogging torque at this position (attraction force generated between the stator 104 and the magnet 104 acting on the magnet 101) is T3, which is a positive force in the rotational direction toward the point E2 (clockwise in FIG. 5). Power) will work. That is, the holding force at the position where the other end surface of the stopper groove 105b of the base plate 105 contacts the pin 101g of the magnet 101 becomes T1. In the state of FIG. 4 and the state of FIG. 5, the magnet 101 is set to be rotated by θ degrees.
[0064]
As described above, the driving device switches the direction of energization to the coil 102 so that the magnet portion of the magnet 101 switches from the state of FIG. 4 to the state of FIG. 5 or from the state of FIG. 5 to the state of FIG. Can be done.
[0065]
By providing a biasing means, such as the torsion coil spring 108, in the driving device as described above, the state shown in FIG. 4 is always maintained when the coil 102 is not energized. The urging force of this urging means (torsion coil spring 108) is larger than the cogging force in the direction opposite to the direction urged by the urging means acting in the state of FIG. 4, that is, T1 and acts when the coil 102 is energized. It is set smaller than the driving force T3 (see FIG. 6). Thus, when the coil 102 is not energized, the state shown in FIG. 4 is maintained, and when the coil 102 is energized, the coil 102 overcomes the urging force of the urging means and is driven stably. By setting the outer magnetic pole portion of the stator 104 as described above and minimizing the cogging force, the urging force of the urging means can be set small, whereby the driving force of the magnet 101 can be increased, and the Drive. Overall, the drive can be designed to be very small.
[0066]
The light amount adjusting blade 106 rotates in conjunction with the magnet 101. When the magnet portion of the magnet 101 is in the state shown in FIG. 5, the light amount adjusting blade 106 is at a position retracted from the opening, and when the magnet portion of the magnet 101 is in the state shown in FIG. Driven to closed position. Therefore, by switching the direction of energization to the coil 102 (when driving from the state of FIG. 5 to the state of FIG. 4, the energizing means may be provided to simply cut off the energization), the The position can be controlled between the open position and the closed position, and the amount of light passing through the opening of the light amount adjusting device can be controlled.
[0067]
The present driving device also has the following features.
[0068]
The magnetic flux generated by energizing the coil 102 crosses the magnet between the outer magnetic pole portions 104a, 104b and the inner magnetic pole portion 104c, so that it works effectively.
[0069]
Since the outer magnetic pole portions 104a and 104b are formed in a tooth shape or a comb shape extending in a direction parallel to the axial direction of the cylindrical magnet 101, the outer magnetic pole portions 104a and 104b are formed in a radial direction toward the center of the shaft. The dimension in the diametrical direction can be configured to be smaller than that of the one. Thus, a very small diameter cylindrical actuator can be obtained.
[0070]
Since the coil 102 is formed as a single unit, the power supply control circuit is simplified, and the cost can be reduced. In addition, since the coil 102 is arranged in the axial direction with the magnet 101, and the rotation center of the magnet 101 is arranged in parallel with the optical axis of the light amount adjusting device, the coil 102 has a small diameter and is formed on the base plate of the light amount adjusting device. A compact driving device in which the magnet does not occupy a large area can be provided, and the light amount adjusting device can be made very small.
[0071]
As described above, it is possible to provide a light amount adjusting device having a high output, an inexpensive, extremely small, and stable driving actuator.
[0072]
In the above example, the torsion coil spring 108 is provided on the outer peripheral portion of the cover 107, but may be provided outside the outer magnetic pole portion of the stator 104 and inside the cover 107.
[0073]
(Second embodiment)
13 and 14 are views showing a light amount adjusting device according to a second embodiment of the present invention. More specifically, FIG. 13 is an exploded perspective view of the light amount adjusting device, and FIG. 14 is a perspective view of the light amount adjusting device. FIG. The same parts as those in FIG. 1 and the like according to the first embodiment are denoted by the same reference numerals.
[0074]
In the second embodiment, the urging means of the first embodiment is arranged so as to overlap in the axial direction of the main plate.
[0075]
Reference numeral 115 denotes a base plate similar to the base plate 105 of the first embodiment, and further has a base plate having projections 115c and 115d for disposing an urging means described later. Numeral 118 denotes an urging means for urging the magnet 101 in the same direction as the torsion coil spring 108 according to the first embodiment. The biasing means 118 is also an example of a torsion coil spring, has a coil diameter D3 smaller than the diameter D1 of the cover 107, hooks one end of the coil D101 onto the pin 101g of the magnet 101, and connects the other end thereof. The base plate 115 is fixed by a protrusion 115d.
[0076]
The first embodiment is different from the first embodiment only in the urging means, and the driving mechanism of the driving device is the same as that of the first embodiment, so that the description thereof is omitted.
[0077]
According to the above configuration, the biasing means 118 is configured to be overlapped in the axial direction of the driving device, so that the diameter of the light amount adjusting device is equal to the diameter of the driving device, that is, the magnet diameter and the stator thickness opposed thereto and the distance between the magnet and the stator Since the dimension parallel to the axis is determined by the height of the stator, the thickness of the ground plane, and the biasing means, a very small cylindrical light amount adjusting device is obtained.
[0078]
(Third embodiment)
15 and 16 are views showing a light amount adjusting device according to a third embodiment of the present invention. Specifically, FIG. 15 is an exploded perspective view of the light amount adjusting device, and FIG. 16 is a perspective view of the light amount adjusting device. FIG. The same reference numerals are given to the same components as those in FIG. 1 and the like in the first embodiment.
[0079]
In the third embodiment, the biasing means is located at a position overlapping with the stator 104 when viewed from a direction perpendicular to the axial direction, and at a portion avoiding the outer magnetic pole portions 104a and 104b of the stator 104. It was done.
[0080]
Reference numeral 117 denotes a cover similar to that of the first embodiment. In addition, a notch 117b is provided at a position that does not overlap the outer magnetic pole portions 104a and 104b of the stator 104 in the radial direction.
[0081]
Reference numeral 128 is fixed around the cut portion 117b of the cover 117, and overlaps the cut portion 117b of the cover 117 and the outer magnetic pole portions 104a, 104b of the stator 104 in the axial direction, but avoids the outer magnetic pole portions 104a, 104b. The spring arm 128b is a leaf spring that is arranged in the portion and extends in the axial direction of the main plate 105 and in the direction perpendicular to the axis. The tip of the spring arm 128b urges the pin 101g of the magnet 101 in the same direction as the torsion coil spring 108 of the second embodiment.
[0082]
The first embodiment is different from the first embodiment only in the urging means, and the driving mechanism of the driving device is the same as that of the first embodiment, so that the description thereof is omitted.
[0083]
According to the above configuration, by arranging the urging means for urging the magnet 101 in the gap avoiding the outer magnetic pole portions 104a and 104b of the stator 104, a space can be effectively used and a very small light amount adjustment can be achieved. It can be a device.
[0084]
In the first to third embodiments, the light amount adjusting blade is a single blade adhered to the magnet, which is a rotor. However, the light amount adjusting blade is rotated by a rotation center different from the rotation axis of the driving device. A blade driven by being slidably fitted with a pin of a rotating rotor may be used. The number of blades may be one or two or more.
[0085]
In the case where the light amount adjusting blade is an aperture blade having an aperture diameter at the center, the position held by the urging means when the coil is not energized may be the position where the light amount adjusting blade is retracted from the opening.
[0086]
Finally, the effects of the first to third embodiments will be summarized and the following description will be given while clearly showing the relationship with the constituent elements of the claims.
[0087]
1) A rotor 101 having a cylindrical magnet portion, a coil 102, a tooth-shaped outer magnetic pole portion, inner magnetic pole portions 104a and 104b (or one or more), and an inner magnetic pole portion 104c are provided. The outer magnetic pole portions 104a, 104b are opposed to the outer peripheral surface of the magnet portion within a predetermined angle (A degree) range, and the outer magnetic pole portions 104a, 104b The ratio between the predetermined angle A facing the magnet portion and the angle per magnetized pole of the magnet portion is Y, and the ratio of the magnet portion per magnetized pole to the radial thickness of the magnet portion is Y Assuming that the value of the ratio of the lengths on the circumference of the circle is X, the configuration is set so as to satisfy the condition of “−0.3x + 0.72 ≦ Y ≦ −0.3X + 0.63”. That.
[0088]
By satisfying the above conditions, the magnetic pole portion is excited, and the attraction force between the magnet and each magnetic pole portion, which sometimes acts as a force opposing the rotating force of the magnet generated thereby, is drastically reduced. That is, it is possible to suppress the cogging force in the opposite direction to the driving direction when the coil is energized and driven, thereby increasing the rotational force of the magnet.
[0089]
Therefore, a driving device (stepping motor) that can generate a large amount of energy generated by exciting each of the magnetic pole portions as a rotating force, and can perform smooth rotation with high output and small power. It can be. This also leads to downsizing of the driving device.
[0090]
2) A driving device having the above-described configuration, and a light amount adjusting member (light amount adjusting blade 106) that operates with rotation of the rotor 101 (magnet portion) as a component of the driving device and adjusts an opening amount of the opening. , The generation of the attractive force between the magnet portion and the outer magnetic pole portion can be minimized, and the movement of the light amount adjusting member can be made smooth even with a small electric power. .
[0091]
3) When the current is not supplied to the coil, the rotor is adjusted so that the light amount adjusting member brings the opening into a predetermined opening state, specifically, puts the opening into a completely closed state. A light amount adjusting device having an urging means (torsional coil spring 108 and urging means 118 and 128) for urging the rotor 101 (magnet portion) to be energized, thereby reducing the urging force of the urging means. This allows the light amount adjusting member to be operated to a desired opening state against the urging force of the urging means with a small amount of power when energized, and to adjust the light amount by the urging means when no electric power is supplied. The member can be moved to the initial state, and the state can be stably maintained.
[0092]
4) Another effect unique to each embodiment is that the biasing means overlaps the outer magnetic pole portions 104a, 104b of the stator 104 when viewed from a direction perpendicular to the axial direction, and the outer magnetic pole portions 104a, 104b. By arranging them at positions avoiding the above, the empty space of the driving device can be effectively used, and the light amount adjusting device can be made very small.
[0093]
As described above, it is possible to configure an ultra-small drive device in which the magnet 101 minimizes the cogging force attracted to the outer magnetic pole portions 104a, 104b, and the provision of the urging means (108, 118). In addition, the rotor, that is, the light amount adjusting member can be held at a predetermined position even when the coil is not energized, so that it is possible to provide a light amount adjusting device that is small and has a large driving torque and performs stable driving.
[0094]
【The invention's effect】
As described above, according to the first aspect of the invention, the generation of the attractive force between the magnet portion and the outer magnetic pole portion is minimized, and the energy generated by exciting the outer magnetic pole portion is reduced. An object of the present invention is to provide a drive device that can make a large amount of rotational force, and that can perform smooth rotation with high output and low power.
[0095]
According to the second aspect of the present invention, it is possible to minimize the generation of an attractive force between the magnet portion and the outer magnetic pole portion, and to make the movement of the light amount adjusting member smooth even with a small power. It is possible to provide a light amount adjusting device capable of performing the above operation.
[0096]
According to the third or fourth aspect of the present invention, it is possible to reduce the urging force of the urging means, and to adjust the amount of light against the urging force of the urging means with a small amount of electric power when energized. A light amount adjusting device capable of operating a member to a desired opening state and moving the light amount adjusting member to an initial state by the urging means when no power is supplied, and stably maintaining the state. It is.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a light amount adjusting device according to a first embodiment of the present invention.
FIG. 2 is a perspective view of the light amount adjusting device of FIG. 1;
FIG. 3 is a cross-sectional view of the light amount adjusting device of FIG.
FIG. 4 is a sectional view taken along the line BB of FIG. 3 when the shutter has entered the opening and the shutter is closed.
FIG. 5 is a sectional view taken along line BB of FIG. 3 when the shutter retracted from the opening is opened.
FIG. 6 is a diagram showing a state of a cogging torque and a torque generated at the time of energization in the first embodiment of the present invention.
FIG. 7 is a diagram illustrating a relationship between a width dimension of an outer magnetic pole portion, a cogging torque, and a magnet dimension according to the first embodiment of the present invention.
FIG. 8 is a diagram showing types of driving devices used for obtaining each relationship.
FIG. 9 is a diagram illustrating a relationship between torque and a rotation phase of a rotor, which is an experimental result according to the first embodiment of the present invention.
FIG. 10 is a diagram illustrating a relationship between torque and a rotation phase of a rotor, which is an experimental result according to the first embodiment of the present invention.
FIG. 11 is a diagram illustrating a relationship between torque and a rotation phase of a rotor, which is an experimental result according to the first embodiment of the present invention.
FIG. 12 is a diagram illustrating a relationship between a width dimension of an outer magnetic pole portion, a cogging torque, and a magnet dimension of the experimental model according to the first embodiment of the present invention.
FIG. 13 is an exploded perspective view of a light amount adjusting device according to a second embodiment of the present invention.
14 is a perspective view of the light amount adjusting device of FIG.
FIG. 15 is an exploded perspective view of a light amount adjusting device according to a third embodiment of the present invention.
FIG. 16 is a perspective view of the light amount adjusting device of FIG.
FIG. 17 is an exploded perspective view of a conventional light amount adjusting device.
[Explanation of symbols]
101 rotor
102 coil
104 Stator
104a, 104b Outer magnetic pole
104c inner magnetic pole
105 Ground plate
106 Light control blade
107, 117 cover
108, 118, 128 biasing means (torsion coil spring)

Claims (4)

An outer peripheral surface has a cylindrical magnet portion which is divided in the circumferential direction and alternately magnetized to different poles, a rotor rotatable around a rotation center, and a coil arranged in the axial direction of the rotor, A drive having at least one tooth-shaped outer magnetic pole portion and an inner magnetic pole portion, wherein the outer magnetic pole portion and the inner magnetic pole portion face the outer peripheral surface and the inner peripheral surface of the magnet portion, and have a stator excited by the coil. In the device,
The tooth-shaped outer magnetic pole portion facing the outer peripheral surface of the magnet portion faces a predetermined angular range of the outer peripheral surface of the magnet portion, and the predetermined outer magnetic pole portion faces the magnet portion. Y is the ratio of the angle to the angle per magnetized pole of the magnet unit, and the ratio of the length of the magnet unit on the circumference per magnetized pole to the radial thickness of the magnet unit. Assuming that the value is X, −0.3X + 0.72 ≦ Y ≦ −0.3X + 0.63
A driving device characterized in that it is set so as to satisfy the following conditions. The outer peripheral surface has a cylindrical magnet portion which is divided in the circumferential direction and is alternately magnetized to different poles, a rotor rotatable around a rotation center, a coil arranged in the axial direction of the rotor, and A drive device having at least one tooth-shaped outer magnetic pole portion and an inner magnetic pole portion, wherein the outer magnetic pole portion and the inner magnetic pole portion face the outer peripheral surface and the inner peripheral surface of the magnet portion, and have a stator excited by the coil. When,
A light amount adjusting device having a light amount adjusting member that operates with the rotation of the rotor that is a component of the driving device and adjusts an opening amount of an opening,
The tooth-shaped outer magnetic pole portion facing the outer peripheral surface of the magnet portion faces a predetermined angular range of the outer peripheral surface of the magnet portion, and the predetermined outer magnetic pole portion faces the magnet portion. Y is the ratio of the angle to the angle per magnetized pole of the magnet unit, and the ratio of the length of the magnet unit on the circumference per magnetized pole to the radial thickness of the magnet unit. Assuming that the value is X, −0.3X + 0.72 ≦ Y ≦ −0.3X + 0.63
Characterized in that it is set so as to satisfy the following condition. 3. The light amount adjusting device according to claim 2, further comprising: urging means for urging the rotor so that the light amount adjusting member brings the opening into a predetermined opening state when the coil is not energized. apparatus. 3. The device according to claim 2, further comprising: urging means for urging the rotor so that the light amount adjusting member completely closes the opening when the coil is not energized. Light control device.

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