JPH07319006A - Quantity-of-light controller - Google Patents

Abstract

PURPOSE:To provide a quantity-of-light controller where the shifting force in one direction of a quantity-of-light control member can be gotten, effectively making use of a means which can reduce detent torque. CONSTITUTION:This has a drive source, which has a pair of stator yokes 3-1 and 3-2 which have a plurality of magnetic poles being arranged in opposition, forming vacant space to the rotor magnet 2 consisting of a permanent magnet and on which driving coils are wound, and quantity-of-light control members 6 and 7, which are driven by a driving source within the range of 180 deg. or under, supposing that the rotor magnet 2 of the drive source is magnetized in, for example, two poles, and the angles of apertures of both magnetic poles are different from each other, and besides they are not less than 90 deg., and the angles of apertures of both magnetic poles are constituted to be asymmetrical about the center of the rotation of the rotor magnet 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light quantity control device mounted on a photographing device such as a video camera.

[0002]

2. Description of the Related Art As shown in FIG. 23A, for example, a light quantity control device mounted on a photographing device such as a video camera has a rotor on the outer circumference of a rotor magnet 82 which is composed of permanent magnets and which is magnetized in two poles. A magnet 82 and a yoke 83 forming a magnetic circuit are provided, and the rotor magnet 8
The light amount control member 86, which is a light-shielding member, is driven by a motor that is an inner magnet type drive source 89 in which a drive coil 81 and a braking coil 85 that detects the rotation speed of the rotor magnet are installed in the gap between the second magnet 2 and the yoke 83. I am trying to do it.
Reference numeral 84 is a Hall element that detects the rotational position of the rotor magnet 82 from the magnetic flux of the rotor magnet 82, and 87 is a return spring that biases the light amount control member 86 in the closing direction.

FIGS. 23 (b) and 23 (c) show FIG. 23 (a).
Shows the state in which the camera is equipped with the light amount control device shown in
Is an optical space, D is a lens barrel space, h1 is a camera deck width, V1 is a height obtained by adding the camera deck height and the lens barrel space, and the light amount control member 86 is rotationally driven by the drive source 89 for h2. In order to support the lens movably outside the lens barrel space D,
The width of the camera increased by installing 4 and V2 indicates the height of the camera increased by using the cylindrical inner magnet type motor.

FIG. 24 is a block diagram of a light quantity control device using this inner magnet type motor as a drive source. A is a lens portion of a video camera, B is a control circuit portion of the camera, and a zoom motor is included in the lens portion A. 100, a braking coil 101 integrated with a drive source 102 of a light amount control device, a detection device (hall element 84) 103a of a position detection means 103, an autofocus motor 104, and a light amount detection device for detecting the light amount of a subject that has passed through a photographing optical system. And a control circuit B of the camera which processes a signal from the light amount detecting device 105 into a video signal and outputs the video signal as a video signal.
06, a control circuit 107 for driving and controlling the autofocus motor 104 for focusing based on a signal from the light amount detecting device 105, and a drive amount setting means 108 for setting a drive amount for opening and closing the diaphragm. And an amplifier 110 for amplifying the speed information from the braking coil 101, the speed information from the amplifier 110 and the drive amount setting means 108.
Comparison means 11 for controlling energization to the drive coil of the motor for driving the light amount control member 86 based on the comparison of the information from
1 and further includes an amplifier 103b that amplifies the position information detected by the detection device (Hall element 34) 103a of the detection means 103, and the position information from the amplifier 103b is input to the drive amount setting means 108.

The conventional light quantity control device having such a configuration is
In order to open / close the light amount control member 86 gently and smoothly, the rotation speed of the rotor magnet 82 is detected by the braking coil 101, and the speed control is performed to the position where the optimum light amount is obtained, and the closing direction is returned. The biasing force of the spring 87 drives the light amount control member 86.

On the other hand, the mechanical drive mechanism constituting the light quantity control device and the electric control circuit are separately arranged, the control circuit to the control circuit section of the camera and the drive mechanism to the lens section. A printed circuit board 88, which is provided and is an interface on which the hall element 84 and the connector are mounted, and a flexible printed circuit board (not shown) that connects the printed circuit board and the camera control circuit are connected to each other.

[0007]

However, in the above-mentioned conventional light amount control device, since the drive source of the light amount control member uses the inner magnet type motor, the following problems have been pointed out.

(1) Since the inner magnet type motor is formed in a cylindrical shape in structure, it pops out from the lens barrel to be mounted,
This has hindered the miniaturization of the lens barrel and the miniaturization of the camera as a whole.

(2) In the inner magnet type motor, it is necessary to install a coil in the space between the rotor magnet and the yoke, and this space is required to be large and uniform. It was used inefficiently. Also, because of this, the coil is placed only within a small air gap, so the number of turns of the coil is not sufficient, and as a result, a rotor magnet with a large volume is used, resulting in an increase in the size and weight of the drive unit. Was increasing.

(3) Since the inner magnet type motor has an anti-cylindrical coil shape, it is difficult to process, and it is difficult to assemble the coil in the air gap, and the disconnection and short circuit. This causes quality problems and causes a decline in productivity.

On the other hand, in contrast to the inner magnet type motor, the outer magnet type motor, such as, for example, Jikkaihei 5-2677 and Kaikaihei 3-298.
When the light amount control member is driven by a stepping motor or the like like 37, the detent torque (rotational force that works to stop the rotor magnet at a stable position) acting between the rotor magnet and the magnetic pole is very large, and the exciting force of the drive coil is increased. It becomes a huge load against the driving force.

For this reason, it has been pointed out that an exciting force sufficient to overcome such a huge detent torque is required, which leads to an increase in the size of the device and an increase in the drive power due to the increase in the size of the drive coil.

Further, even if a rotor magnet having a strong magnetic force is used to reduce the size, a larger detent torque is generated due to the stronger magnetic force and a larger exciting force is required, resulting in an increase in size of the apparatus. Will be invited.

In particular, since the light quantity control device for moving images is always operating, it is necessary to save power, and it is necessary to control the light quantity with smooth changes. Therefore, the step operation, the vibration and the large load fluctuation are required. A certain detent torque has been a major obstacle in using the outer magnet type motor.

As means for setting the stable position of the detent torque, means for providing a portion for narrowing the gap between the rotor magnet and the stator yoke as in the above-mentioned known example, means for forming a notch in the stator yoke, or an iron piece. Although a means for applying the detent torque has been proposed, any of them alone increases the detent torque, and there is no necessary adjusting means for using the detent torque instead of the spring member, and the disadvantages of the step motor and the like described above. The result was worse.

An object of the present invention is to make it possible to substantially cancel or adjust the detent torque by using a means for reducing the detent torque, so that an externally excited motor can be used to achieve performance equal to or higher than that of an inner magnet type motor. The objective is to provide a light quantity control device that is compact, lightweight, high-performance, and high-quality, and that is most suitable for moving images.

[0017]

In order to achieve the above object, the first invention of the present application is to open the opposing magnetic poles of a pair of stator yokes of an outer magnet type motor as means for reducing the detent torque. The angle is larger than 360 degrees / 2P, one opening angle is larger than the other opening angle, and the rotor magnet is installed asymmetrically with respect to the rotation center of the rotor magnet.

In the above structure, the means for reducing the detent torque sets the detent torque which is influenced by the opening angle of the magnetic pole larger than 360 degrees / 2P such that one opening angle is larger than the other opening angle and is asymmetrical. Thus, there is an effect that the detent torque of the opposite phase due to asymmetry is generated and operated to be reduced, and the above means can be realized with a simple structure.

The second invention of the present application has, as means for reducing the detent torque, a pair of main magnetic poles excited by the drive coil of the outer magnet type motor and a pair of non-excited auxiliary poles. The open angles of are all greater than 360 degrees / 2P.

In the above-mentioned structure, the detent torques of the main pole and the auxiliary pole have opposite phases and operate so as to reduce the detent torque, and the opening angle becomes larger than 360 degrees / 2P, and the effective rate of the magnetic force with the rotor magnet. To reduce the adverse effects of leakage flux. A third invention in the present application is characterized in that, as means for adjusting detent torque using means for reducing detent torque, the angular position of magnetic poles of a stator yoke provided with means for reducing various detent torques is adjusted, The detent torque phase and magnitude can be adjusted by simple means.

A fourth aspect of the present invention is a means for adjusting the detent torque using means for reducing the detent torque, wherein the stator yoke of the externally-excited motor has no magnetic pole or an auxiliary motor having an opening angle smaller than that of the main magnetic pole. A pole is provided to shift the angle of 360 degrees / 2P or less from the position where the angle formed by the main pole and the supplementary pole is 360 degrees / 2P to the rotation direction side where the rotor magnet generates detent torque as the return force, and the supplementary pole The gap G _c between the rotor magnet and the rotor magnet is larger than the gap G _m between the main pole and the rotor magnet.

In the above construction, in addition to the means of the third aspect of the invention, by setting the gap of the commutating pole in the direction of expanding it,
The effect of reducing the detent torque can be adjusted, enabling even finer adjustment. The adjustment amount of G _c is 3 × G _m > G
A range of _c > G _m is effective, preferably 2 × G _m ≧ G _c
≧ 1.5 × G _m is preferable.

The fifth invention of the present application is a means for adjusting the phase of the detent torque, and the opening angle of the main pole and the auxiliary pole formed in one stator yoke of the externally excited motor is the main pole. L _f , which is large and is approximately the thickness t _{S of the} stator yoke, the length L _{M of} the rotor magnet, and the gap G _m between the rotor magnet and the main magnetic pole, which represents the ineffective length where the leakage flux of the rotor magnet is possible, is L _f = (L _M −t _S −2 G _m ) / 2 >> 2 × G _m , and the depth L of the notch of the main pole and the auxiliary pole is L _f >L> G _m , and more preferably , L _f / 2>L> 2 × G _m .

In the above structure, when L _f >> 2 × G _m , that is, when the other portion of the rotor magnet is longer than the opposing length of the rotor magnet and the stator yoke, leakage flux from the other portion Is controlled by the depth of the notch of the stator, and there is a remarkable effect when the effective rate U is U = t _S / L _M <0.5.

The sixth invention of the present application is, as a detent torque adjusting means, in a stator yoke of an externally excited motor, a side surface of at least one magnetic pole is asymmetric with respect to the other side surface and is adjacent to the magnetic pole. It is asymmetric with respect to the side surface of the magnetic pole.

In the above structure, by adjusting the gap between the side surface of the magnetic pole and the rotor magnet, the amount of leakage magnetic flux can be adjusted and the detent torque can be finely adjusted. Further, if it is applied to the first invention, good characteristics can be obtained.

The seventh invention of the present application is characterized in that the opening angle of the magnetic pole of the means for reducing the detent torque is the opening angle of the exciting magnetic pole or the non-exciting magnetic pole including the notch of the means for setting the detent torque. And

In the above structure, the detent torque reducing means and the detent torque setting means, which are notches, are used together to enable more delicate adjustment.

[0029]

【Example】

(First Embodiment) FIGS. 1 to 5 are drawings which best show the features of the present invention. The light amount control device shown in the drawing is a light amount control device using a so-called outer magnet type motor as a drive source.

Reference numerals 3-1 and 3-2 denote stator yokes, which are arranged in a direction orthogonal to the optical axis 12 and are arranged in the coil 1.
The coil bobbin 1a around which is wound is attached to the yoke 3-1. Reference numeral 2 denotes a rotor magnet which is arranged with a gap in the circumferential portion formed at the tips of the stator yokes 3-1 and 3-2, and is magnetized to have two poles in the radial direction. A magnetic pole 3a is formed on the circumferential portion of the stator yoke 3-1 and a magnetic pole 3b having an opening angle of 90 degrees or more is formed on the circumferential portion of the stator yoke 3-2.
Are formed so as to be displaced from the facing positions of the magnetic poles 3a, and the side surface 3c opposite to the displaced direction of the magnetic poles 3b is formed to be inclined toward the magnetic poles 3a.

In this embodiment, an optimum detent torque in one direction is generated with respect to the rotor magnet 2 by the magnitude of the open angle of the magnetic poles 3a and 3b and the facing angular position, and further by the side surface 3c of the magnetic pole. In the example, the detent torque urges the rotor magnet 2 in the direction in which the light amount control members 6 and 7 are closed, so that there is no need to use a return spring as in the secondary bundle.

Reference numeral 9 designates a pair of arm portions 9a, 9 on the rotary shaft 9c.
b is a transmission member formed integrally with the rotor magnet 2
The rotating shaft 9c is fixed in the shaft hole of the
The operation pins formed at the tips of a and 9b are engaged with the respective engaging holes of the light amount control members 6 and 7, and the rotation of the rotor magnet 2 causes the light amount control members 6 and 7 to move in the direction in which they face each other. Are made smaller and the aperture diameters are made larger by moving them in a direction away from each other, whereby the light quantity of the lens incident light is adjusted.

Reference numeral 8 is a base plate, and engaging claws 8h, 8i, 8 for engaging and holding the opening 8a and the stator yokes 3-1 and 3-2.
j, 8k, 8L, a bearing 8b that rotatably supports one shaft end of a rotating shaft 9c fixed to the rotor magnet 2, a hall element 4
The opening 8d for the Hall element, the engaging claws 8e, 8f for engaging and holding the Hall element 4, the guide pins 8u, 8x with which the long grooves for supporting and guiding formed in the light amount control members 6, 7 are fitted, Support rails 8y, 8z, 8w for supporting the control members 6, 7 in the optical axis direction by providing a step for each light amount control member, and a bearing cap 13 for supporting the other shaft end of the rotary shaft 9c are engaged and supported. Engaging claws 8c, 8g and supporting portions 8m, 8p, 8n for engaging and supporting the printed circuit board 11 are formed on the back side of the main plate 8, and the motor portion is fitted in a linear portion perpendicular to the radial direction of the optical axis, and the amount of light is also increased. The control members 6 and 7 are also mounted from the same direction as the motor section. Further, it has support rails 10b, 10c, and 10d for supporting the opening 10a and the light amount control members 6 and 7 together with the light amount control member by providing a step in the optical axis direction, and holding the light amount control members 6 and 7 and dust from the outside. The front side opening of the main plate 8 is closed by a case 10 that prevents the intrusion of the above.

A hall element is erected on the printed circuit board 11 and the terminals of the coil 1 are soldered, and the round section 1 for exchanging signals with the control circuit section of the camera.
1a and 11b are formed in a comb shape and are inserted into the holes 20a of the printed circuit board of the control circuit of the camera, as shown in FIG.
It is fixed by soldering as shown in the figure. In particular, the round section 11b also serves as a check round for characteristic operations as a test pattern, in addition to the above purpose.

This printed circuit board does not require connectors or intermediate interface members, eliminates contact failures and noise sources, and enables highly reliable connections, as well as vibrations generated when driving the autofocus motor or zoom motor. There is also an effect of preventing resonance due to. Particularly in the speed control method of differentiating the Hall output according to the present embodiment, it is important that the Hall output does not have noise. The terminals of the Hall element 4 mounted on the printed circuit board 11 have straight-lined terminals and bent terminals, which widen the rounds of the terminals and raise the Hall element 4 away from the printed circuit board 11. It has the role of preventing falling and detecting at a stable position.

FIG. 7 shows a dead space when the lens barrel portion 22 is attached to the camera deck portion 21, where L is an optical space, D is a lens barrel space, and h1.
Is the camera deck width, and V1 is the height that combines the deck height and the lens barrel space. As indicated by the diagonal lines, the dead space is the lens barrel dead space obtained by removing the optical space L from the lens barrel space D, plus the dead space of the camera deck and the lens barrel space.

FIG. 6 shows a state in which the light quantity control device of this embodiment is installed in the dead space, and 23 and 24 are guide bars for movably supporting the lens. In this way, since the light amount control members 6 and 7 move straight in a direction in which they face each other, the guide bar can be provided in the space inside the lens barrel, and the drive unit is provided with the drive unit as shown in FIG. While arranging at a right angle to the direction of straight movement of
The rotation center of the rotor magnet 2 is measured from the center of the optical axis by the dimension S
It is possible to form a substantially L-shaped light quantity control device by shifting the amount by the amount, and it is possible to store the light quantity control device in the dead space.

That is, the entire camera can be made compact, and the camera can be installed in the lens barrel by inserting it later. With a structure suitable for connecting and fixing the printed circuit board 11, maintenance, correction, Replacement and assembly work can be facilitated.

Next, a video camera equipped with the above-described light quantity control device will be described with reference to the block diagram shown in FIG. Incidentally, the same means as those in the block diagram of FIG. 24 are designated by the same reference numerals and the description thereof will be omitted.

Light incident on the taking lens is controlled by the light quantity control member 6,
An image is formed on the light amount detection device 105 composed of a CCD through the opening formed by 7, and the optical signal is converted into an electric signal to output a video signal YS.

Upon receiving this video signal YS, the drive amount setting means 108 sets the drive amount information VP of the light amount control members 6 and 7 based on the table set in the memory 109 together with the operation amount information of the detecting means 200. The incident light quantity is set to an appropriate value and output to the comparison means 202.

In the comparison means 202, the drive coil 1 of the drive source 201 is excited based on the drive amount information VP, and the rotor magnet 2 is rotationally driven by the attracting action and repulsive action of the rotor magnet 2 through the stator yoke 3. When the rotor magnet 2 rotates, the light amount control members 6 and 7 move linearly in a direction in which they face each other via the transmission member 9,
The lens incident light is adjusted to operate so as to obtain a proper exposure amount. The rotation range of the transmission member 9 is restricted by the base plate 8, and the rotor magnet 2 has 360 degrees / P (P is the number of poles: 2).
Since the rotor magnet 2 is magnetized to have two poles in the range below the above integer), in the present embodiment, rotation within a range of 180 degrees is allowed.

When the rotor magnet 2 rotates, the detecting means 200 including the Hall element 4 detects the rotational position of the rotor magnet 2 from the change in the output.

The position information VF from the detecting means 200 is position information and can be used as it is to control the rotation range of the rotor magnet 2, and the rotor magnet 2 is required in the video camera for light quantity control. It cannot be used to spin at slow speeds. Therefore, in this embodiment, the position information VF is input to the correction unit 203, corrected by the differentiating circuit of the correction unit 203 to drive speed information VS, and output to the comparison unit 202.

The comparing means 202 feeds back the drive speed information VS proportional to the rotation speed of the rotor magnet 2 to the drive quantity information VP output from the drive quantity setting means 108 in response to the input of the position information VF, and calculates the difference between them. It outputs certain drive control information VD to the drive coil 1 of the drive string 201. The output of the detection means 200 changes to a substantially linear signal between peaks of a sine wave, for example, because the rotor magnet 2 is magnetized in two poles and rotates within an angle range of 180 degrees. To do.

FIG. 8 shows the construction of a concrete drive circuit for the comparison means 202, drive source 201, detection means 200, and correction means 203 shown in FIG.

This drive circuit performs feedback control of negative feedback, and the detection means 200 has an amplifier for amplifying and adjusting the output of the hall element 4 to output the operation amount information VF which is also position information, and the correcting means 203. Has a differentiating circuit for differentiating the operation amount information VF to convert it into the driving speed information VS, and VR is a reference voltage. The comparison means 202 has an integration circuit that compares the drive speed information VS and the drive amount information VP and outputs the difference to the drive coil 1 as drive control information VD.

The operation of the drive circuit will be described with reference to FIG. 10 which shows the change in the signal of each circuit in a correlated manner.

FIG. 10A shows the drive amount information VP,
The drive amount information V is centered on the value of the reference voltage VR so that the light amount YS always approaches the set target value or the operation amount information VF approaches the target value according to the change of the light amount.
Change P. Here, the light amount control member is stopped at the level of the reference voltage VR, and a close signal for closing the light amount control member is output when the reference voltage VR or higher, and an open signal for opening the light amount control member is output when the reference voltage VR or lower. Therefore,
The larger the difference between the control amount such as the light amount YS and the target value, the larger the level difference between the reference voltage VR and the drive amount information VP.

FIG. 10B shows the drive control information VD, and the drive control information VD obtained by integrating the difference between the drive amount information VP and the drive speed information VS is applied to the drive coil 1. L ₀
Indicates a voltage level corresponding to the return torque due to the detent torque. When the drive control information VD matches L ₀ , it stops, when it exceeds it, it drives the light amount control member in the open side, and when it drops, it drives the light amount control member in the closing direction.

FIG. 10C shows the operation amount information VF. The amount of operation of the rotor magnet 2 is linearly and directly detected by the Hall element 4 according to the drive control information VD. The control member is adjusted to 1 volt (V) at the open end and 3 V at the closed end, and its voltage level corresponds to the rotational position of the rotor magnet 2 and the aperture diameter (aperture value) of the light amount control member.

FIG. 10D shows the driving speed information VS output from the correcting means, and this driving speed information VS is
This signal is a signal obtained by differentiating the motion information VF, and the faster the changing speed of the motion information VF is (the larger the slope of the motion information VF is), the larger the output is, and thus the signal is proportional to the rotation speed of the rotor magnet 2. Here, when the drive speed information VS matches the reference signal VR, the speed is 0, the reference signal V
When it is larger than R, the speed in the opening direction is detected, and when it is smaller than the reference signal VR, the speed in the closing direction is detected.

In such a drive circuit, the drive control information VD rises according to the open signal of the drive amount information VP, and when the voltage level L ₀ is exceeded, the rotor magnet 2 starts rotating and is accelerated. With this condition, it reaches the open end, which is a slight rotation range, in a few ms at a stroke,
It passes the target value. On the other hand, with the close signal of the drive amount information VP, on the contrary, the step operation cannot be performed close to the target value, such as to the close end.

Therefore, the driving speed information VS proportional to the changing speed of the movement amount information VF is negatively fed back to the driving amount information VP,
The difference is used as drive control information VD.

When the rotor magnet 2 accelerates to rotate for the first time, the motion amount information VF abruptly changes accordingly, so that the drive speed information VS abruptly rises. Then, as a result of comparing the drive speed information VS and the operation amount information VF, the drive amount information VP starts to drop, and the level of the drive amount information VP is lowered from L ₀ to generate the torque in the closing direction. Therefore, the rotation speed of the rotor magnet 2 slows down and tries to stop, but the changing speed of the operation amount information VF also becomes slow, so that the driving speed information VS also approaches the reference signal VR.

However, as a result of comparing the drive speed information VS and the drive amount information VP, the drive control information VD rises,
The level rises above the level L ₀ and the rotor magnet 2 starts to accelerate.

With such a negative feedback operation, it is possible to finely and stably control the one-phase excitation type motor that causes the step operation.

Therefore, according to the operation of this embodiment, the rotor magnet 2 can operate smoothly at a low speed even in a small rotation range, and the unstable operation of the light amount control such as hunting is improved. As a result, it is possible to obtain an outer magnet type light quantity control device capable of fine and smooth light quantity control.

Further, in this embodiment, the rotor magnet 2 is provided with a spring in the direction in which the light amount control members 6 and 7 are closed by an appropriate detent torque set by the offsetting means and adjusting means of the magnetic poles of the stator yokes 3-1 and 3-2. When the drive coil 1 is energized and the drive coil 1 is not energized, the light amount control member automatically returns to the closed position by this spring biasing force. Of course, the method is not limited to this method, and may be a method of canceling the detent torque almost completely.

Next, the detent torque canceling / adjusting means used in this embodiment will be described with reference to FIGS.

FIG. 11 shows that the detent torque is canceled by the open angle of the magnetic pole and the opposing angular position, and the number of magnetic poles magnetized in the rotor magnet Mg is P (P = 2 in this embodiment). In this case, the opening angles θa and θb of the magnetic poles A and B that form a uniform gap with the rotor magnet are θa =
If θb> 360 ° / 2P and θa and θb symmetrically face each other, as shown in FIG. 11A, the polarity of the magnetic pole SN of the rotor magnet 2 in the direction orthogonal to the facing portion of the yoke. Detent torque acts on.

On the other hand, as shown in FIG. 11B, the opening angle θb of the magnetic pole B is adjusted within the range of θa>θb> 360 ° / 2P, and the opposing position a of the center of the opening angle of the magnetic pole A is adjusted. −
By shifting the position b of the center of the open angle of the magnetic pole B with respect to a ′ by the angle σ, the magnetic flux F flowing in the magnetic pole B is opposed to the magnetic pole A.
To generate detent torque of opposite phase. If the magnetic poles are not displaced, this component is generated on both sides, and the detent torque of the opposite phase is canceled out, and if the open angle is 360 ° / 2P or more, the result of FIG. 11 (a) and the detent torque are I don't change much. Due to the anti-phase detent torque generated by this asymmetric portion, the magnetic pole A
The detent torque generated in (and the magnetic pole B) can be almost completely canceled out. Note that x indicates a stable point and O indicates an unstable point.

FIG. 12 shows a modification of the embodiment shown in FIG. 11 (b). This embodiment differs from the embodiment shown in FIG. 11 (b) in that the side surface of the magnetic pole B faces the magnetic pole A. An angle parallel to a plane f-f 'passing through the center of the minimum gap between the magnetic poles A and B and the center of rotation of the rotor magnet, with the side surface C opposite to the rotational direction displaced from the position tilted toward the opposing magnetic pole A side. The angle of inclination is more σ than that, so that the amount of the leakage magnetic flux F flowing into the magnetic pole A is adjusted to obtain an optimum detent torque.

With this detent torque, the rotor magnet Mg is urged in the closing direction (-rotational direction). In this case, the deviation angle γ is 36 in the opening direction (+ rotational direction).
It is installed at an angle within 0 ° / 2 × 2.

FIG. 13 shows a second embodiment of the present invention. Only the differences from the configuration of the first embodiment shown in FIG. 1 will be described, and the description of the other parts will be omitted.

Reference numeral 43 is a stator yoke composed of two-divided structure stator yoke portions 43-1 and 43-2 having main magnetic poles 43b and 43c, and a complementary pole yoke portion 49 having complementary poles 49b and 49c. 43-1 and 43-2
Is mounted on a bobbin around which a drive coil 41 is wound, and a rotor magnet 42 is arranged in these magnetic poles and auxiliary poles with a certain gap, and a stator yoke portion 43 is provided. -2 and the compensating pole yoke part 49, bearing holes 43a and 49 for supporting the shaft part of the rotor magnet.
a is formed.

Reference numeral 44 denotes a Hall element, which is attached to a substrate 51 on which a drive circuit as shown in FIG. 1 is mounted so as to extend in the optical axis direction.

The rotor magnet 42 is composed of a plastic magnet in which the transmission member 42a and the rotary shaft 42b are integrally formed, and is magnetized to have two poles in the radial direction.

Here, the main magnetic poles 43b and 43c and the auxiliary pole 49
The open angle of b and 49c is 360 ° / 2 × 2 or more, and the angle formed by the main pole and the auxiliary pole is 360 ° / in the closing rotation direction of the rotor magnet 42 from the angular position of 360 ° / 2 × 2.
By shifting within 2 × 2, the detent torque is offset and adjusted, and the rotor magnet 42 is biased in the closing direction with an appropriate return force.

The principle of the detent torque setting and offsetting means described above will be described below with reference to FIGS.
7, 21, 22 will be described.

FIG. 14 shows that the polarities of the detent torque become opposite depending on the opening angle of the magnetic poles.
When the number of magnetic poles magnetized in the rotor magnet Mg in the radial direction is P (P = 2 in this embodiment), if the opening angle θ of the magnetic pole is θ ₁ <360 ° / 2P, As shown in FIG. 14A, the detent torque acts on the polarity where the magnetic pole of SN faces the yoke, and θ ₂ > 3
If it is 60 ° / 2P, as shown in FIG.
The detent torque acts on the polarity of the magnetic pole of SN in the direction orthogonal to the facing portion of the yoke. Note that x is a stable point,
O indicates an unstable point.

FIG. 21 shows this torque characteristic with respect to the rotation angle. FIG. 21 shows the torque characteristic of FIG.
(A) of FIG. 14 shows the torque characteristics of (b) of FIG. 14 in (b) of FIG. 21, respectively. Counterclockwise rotation is positive (open direction),
The N and S positions of the rotor magnet in FIG. 14 are set to 0 °. 21 (a), (b), and (c), a,
c and e show detent torque, and b, d and f show exciting torque by the coil current I.

Utilizing the characteristics of this detent torque,
A method of canceling the detent torque is shown in FIG.

In FIG. 15A, the opening angle θb of the magnetic pole B is set to 36.
Below 0 ° / 2P, open angle θa of magnetic pole A is 360 ° / 2P
In the above example, the detent torques of the magnetic poles B are a as shown in (a) of FIG. 21 and the magnetic poles A have the polarities of c shown in (b) of FIG. The detent torque of FIG. 15A becomes e shown in FIG. 21C and can be substantially offset. At this time,
With a small exciting torque as shown by b and d in 1, a, c
The range that can be driven against the detent torque as shown in is a very small range indicated by diagonal lines, but in FIG. You will be able to drive in the range.

In FIG. 15B, the magnetic pole angle of α = 360 ° / 2P is shifted from the main magnetic pole M by 360 ° /
As shown in FIG.
21 (a), the detent torque due to the main magnetic pole M has the polarity a in FIG. 21 (a), and the commutating pole c has the polarity c in FIG. 21 (b). The detent torque of e in FIG. 21C becomes the detent torque, which can be almost completely offset.

In FIG. 15C, the opening angle θa of the magnetic pole A is 36
0 ° / 2P or more and the opening angle θb of the magnetic pole B is 360 ° /
It is larger than 2P and the facing position aa 'of the magnetic pole A
From the angle γ, and open angles θa and θb are 360 ° /
Since it is larger than 2P, the polarity of the detent torque of c in FIG. 21B becomes the polarity, and the detent torque due to the asymmetric portion becomes the polarity of a in FIG. As a result, (c) of FIG.
It becomes the detent torque of e in FIG.

FIG. 15D shows 360 ° / 2 obtained by shifting the angle of the magnetic pole with the angle α = 360 ° / 2P with respect to the main magnetic pole M.
By providing the compensating poles having the same opening angle larger than P and staggering in the thrust direction, the same effect as in FIG. 15B is obtained, and the detent torque due to the main magnetic pole M is as shown in FIG.
21 (b) has a polarity of c and the commutating pole C has a polarity of a in FIG. 21 (a). As a result, the detent torque of e in FIG. 21 (c) can be almost completely offset. It will be possible.

FIG. 16 shows a method of adjusting the detent torque by utilizing the above four canceling means.

FIG. 16A shows the magnetic pole B from the position facing the magnetic pole A having the polarity of the detent torque of g shown in FIG. By shifting the angle γ to the angle γ, the phase of the detent torque at the magnetic pole B shifts to the + rotation direction side as shown by h in FIG. 22B, and the resultant force of these two is the curve i shown in FIG. 11C. Then, the detent torque is canceled out and the curve g,
The phase is shifted so that the peak of the exciting torque j and the peak of the opposite polarity of the detent torque i are approximately ⅓ of h and substantially coincide with each other. The rotation direction of + corresponds to the opening rotation direction of the rotor magnet Mg and conversely to the closing rotation direction.

Similarly, in FIG. 16B, the angle between the main pole M and the auxiliary pole C in FIG. 15B is α = 36.
From the 0 ° / 2P position, the angle β is 360 in the closing rotation direction.
Offset / adjust detent torque by shifting within ° / 2P.

Further, in FIG. 16C, the detent torque is offset-adjusted within the range of 360 ° / 2P>γ> 0 by further increasing the angle γ in FIG. 15C.

FIG. 16D shows an angle β of 360 ° / 2P in the closing rotation direction from the position of α = 360 ° / 2P where the angle between the main magnetic pole M and the auxiliary pole C in FIG. 15D is α. Offset and adjust the detent torque by shifting within.

The usable range of such a motor as shown in FIG. 22 is a range in which the detent torque i is used as the return torque and the detent torque i is overcome by the exciting torque j to drive the motor. The resultant force k of i and the excitation torque j is the open torque, and i is the close torque. In this case, it is desirable to adjust the detent torque i to about 1/2 of the exciting torque j.

FIG. 17 shows a magnetic pole provided with a notch.
17 (a), (b), and (c) correspond to FIG.
By providing a notch in the magnetic pole A in (c) and (d) and setting the opening angle θa of the exciting magnetic pole A including the notch to be larger than 360 ° / 2P, the opening angle is larger than 360 ° / 2P. The desired detent torque is obtained by increasing the detent torque component of the magnetic pole A, which is combined with the canceling / adjusting means.

FIG. 17 (b) is similar to FIGS. 16 (a) and 16 (b).
In the application example of (b), the open angle is 360 ° / 2 in the same stator.
The main magnetic pole M1 (M2) larger than P and the auxiliary pole C1 (C2) of 360 ° / 2P or less are formed in the return direction so that the angle δ is larger than 360 ° / 2P. Offset / adjust detent torque.

In the embodiment shown in FIG. 18, in addition to the method shown in FIG. 17 (b), the depth L of the notch is further adjusted as a means for expanding the gaps G _c between the commutating poles C1 and C2 and the rotor magnet 2. 18 (a) is an example of a stator yoke shape in which the offset amount of detent torque is adjusted by performing
The plan view, FIG. 18 (b) shows the f-f 'sectional view of FIG, G _c to uniform gap G _m of the rotor magnet 2 and the main magnetic pole M1, M2, here

[0087]

[Outer 1]

Further, as shown in FIG. 18B, the effective rate U of the rotor magnet thickness L _{M with} respect to the stator thickness t _S.
Is U = t _S / L _M <0.5, the leakage flux F1 from the side surface of the rotor magnet 2 to the upper and lower surfaces of the stator,
The influence of F2, F3, and F4 is remarkable, and adjustment is difficult only with the above-mentioned means, but by utilizing this, the effective length L in the thrust direction of the portion where the leakage flux of the rotor magnet appears is roughly represented.
_f is L _f = (L _M −t _S −2 G _M ) / 2 >> 2 × G _m , L _f >L> G _m , and more preferably L _f / 2>
The detent torque can be set finely by adjusting the depth L of the notch within the range of L> 2 × G _m .

The embodiment shown in FIG. 19 shows an embodiment of the stator yoke in which the detent torque canceling means of the embodiment shown in FIG. 15C cancels the detent torque substantially completely within the range of the angle λ.

In FIG. 19, the magnetic pole A having an opening angle θ _a larger than 360 ° / 2P is connected to the Yuusuru stator yoke St.
Excitation drive coil 1 is wound around 3 and 360 ° / 2P
The center of the larger opening angle θ _b is the facing position a− of the magnetic pole A.
a magnetic pole B arranged at an angle γ from a ′ and the magnetic pole B
The side surface opposite to the deviation angle γ direction is made closer to the opposite magnetic pole A side, and is closer than the angle parallel to the center of the minimum gap between the magnetic poles A and B and the plane ff ′ passing through the rotational position of the rotor magnet. A stator yoke St4 having a side surface C of a magnetic pole inclined by σ and connected to the stator yoke St3.
And a magnetic pole A of the stator yoke St3 and a magnetic pole B of the stator yoke St4 are arranged to face each other with a uniform gap, P =
The rotor magnet 2 is magnetized to have two poles in the radial direction.

A cylindrical yoke forming a uniform air gap with respect to the rotor magnet as in the conventional example is ideally a motor without detent torque, but in reality, the circularity / coaxiality of the yoke is There are problems such as the above, and detent torque is generated, which adversely affects the operation of the motor. In order to prevent this, high-precision parts and assembly are required, which is a drawback of the conventional example.

On the other hand, in the present embodiment, the detent torque can be offset more satisfactorily and more stably than in the conventional example, but this can be adjusted even if the poor parts are stable, and the weight can be adjusted to the squeeze bar. It's like putting it on and making it stable.

FIG. 20 shows an embodiment of FIG. 17 (a),
The U-shaped stator δt5 is used as the utilization means.

In FIG. 20, the opening angle θ including the notch D
Magnetic pole A where _a is greater than 360 ° / 2P and 360 ° / 2
The center of the opening angle θ _b of P or less is the facing position aa ′ of the magnetic pole A.
And a side surface of the magnetic pole B opposite to the shift angle γ direction are tilted toward the opposing magnetic pole A side so as to be close to each other and the center of the minimum gap between the magnetic poles A and B and the rotor magnet. The stator yoke St5 having the side surface C of the magnetic pole inclined by σ with respect to the angle parallel to the plane ff ′ passing through the rotation position.
The excitation drive coil 1 is wound around the rotor, and is constituted by a rotor magnet 2 which is magnetized in the radial direction to P = 2 poles, which is arranged to face the magnetic pole A and the magnetic pole B with a uniform gap.

In the above-mentioned embodiment, the main magnetic pole refers to one of the stator yoke magnetic poles around which the drive coil is wound, which has a large opening angle, and the auxiliary pole is the stator yoke around which the drive coil is not wound. The magnetic pole or the magnetic pole of the stator yoke around which the drive coil is wound has a small opening angle.

In particular, the notch in FIG. 17 is formed in a magnetic pole larger than the opening angle of 360 ° / 2P to increase the magnitude of detent torque of the same phase, but the notch position is adjusted to The phase of the detent torque may be adjusted (set).

[0097]

As described above, according to the present invention, fine and smooth light quantity control can be performed by a one-phase excitation type motor which is an external magnet type driving source as a driving means, and the light quantity control device can be driven. The external magnet type motor as a power source can be used for a video camera, which is a photographing device for moving images, and in particular, the detent torque generated in the drive source can be offset or reduced. Can be obtained.

(1) It is possible to realize a light quantity control device that can be rotated with a slight driving force.

(2) Since the load is drastically reduced, it can greatly contribute to power saving.

(3) Only a small driving force is required, and the driving source can be downsized and the cost can be reduced.

(4) Even if the magnetic force of the rotor magnet is increased, an appropriate detent torque can be set, a strong driving force can be obtained without increasing the load, and the driving source can be further downsized. can do.

(5) The detent torque can be adjusted freely and finely, and this magnetic force can be used as the returning force of the light quantity control member, which eliminates the need for a mechanical spring and drives the returning force. Since it becomes the same source as the force, the temperature characteristic of the drive control voltage that feeds the drive coil is improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a light amount control device showing a first embodiment of the present invention.

FIG. 2 is a plan view of the light quantity control device of FIG.

FIG. 3 is a rear view of the light quantity control device of FIG.

FIG. 4 is a diagram showing a connection state of the light amount control device of FIG. 1 to a printed circuit board.

FIG. 5 is a diagram showing a mounting state of Hall elements in the light quantity control device of FIG. 1;

FIG. 6 is a diagram showing external dimensions in a state where the light amount control device of FIG. 1 is incorporated in a video camera.

FIG. 7 is a diagram showing external dimensions in a combination state of a lens barrel and a deck portion of a video camera.

8 is a diagram showing details of a drive circuit of the light quantity control device shown in FIG.

9 is a block diagram of a video camera equipped with the drive circuit of FIG.

10 is a diagram showing an output waveform of each signal in the circuit diagram of FIG.

FIG. 11 is a plan view showing a detent torque offsetting / adjusting means in the first embodiment.

FIG. 12 is a plan view showing a modified example of the embodiment shown in FIG. 11 (b).

FIG. 13 is an exploded perspective view showing a second embodiment of the present invention.

FIG. 14 is a diagram showing a principle of generation of detent torque.

15A to 15D show detent torque canceling methods, respectively.

16A to 16D show detent torque adjustment methods, respectively.

17 (a) to (d) show other offset / adjustment methods for detent torque, respectively.

FIG. 18 shows a modification of the detent torque canceling / adjusting means shown in FIG. 17 (b), (a) is a plan view, and (b) is a sectional view taken along the line ff ′ of (a).

FIG. 19 is a plan view of a stator yoke that realizes the detent torque offsetting / adjusting means shown in FIG.

FIG. 20 is a plan view of a stator yoke that realizes the detent torque canceling / adjusting means shown in FIG.

FIG. 21 shows the relationship between rotation angle and detent torque,
14 (a) corresponds to FIG. 14 (a), FIG. 14 (b) corresponds to FIG. 14 (b), and FIG. 14 (c) shows the rotation angle in the combined state of (a) and (b). The relationship with the detent torque is shown.

22 is a diagram showing the relationship between the rotation angle and torque of the detent torque offsetting / adjusting means shown in FIG. 16 (d).

23A is a diagram showing the light amount control device driven by a conventional inner magnet type motor, and FIGS. 23B and 23C are diagrams showing the external dimensions of a video camera incorporating the light amount control device shown in FIG. 23A. .

FIG. 24 is a block diagram of the video camera shown in FIG.

[Description of Reference Signs] 1 ... Coil 2 ... Rotor magnet 3-1, 3-2 ... Stator yoke 3a, 3b ... Magnetic pole 3c ... Side surface 4 ... Hall element 6, 7 ... Light amount control member 8 ... Base plate 9 ... Transmission member 10 ... Case 11 ... Printed circuit board

Claims (14)

[Claims] 1. A drive source having a pair of stator yokes, each of which has a plurality of magnetic poles arranged to face a rotor magnet made of a permanent magnet with a gap therebetween, and a drive coil is wound around the rotor magnet. In the light quantity control device having a light quantity control member driven by the drive source within a range of 360 degrees / P or less when the rotor magnet is magnetized to the number of poles P (an integer of 2 or more), the pair of stators A light quantity control device characterized in that the opening angle of the opposing magnetic poles of the yoke is set to 360 degrees / 2P or more, one opening angle is made larger than the other opening angle, and the yoke is installed asymmetrically with respect to the rotation center of the rotor magnet. . 2. The angle θ formed by the opposing magnetic poles according to claim 1, which is shifted from a position of 360 degrees / P in a direction opposite to a rotation direction in which the rotor magnet generates a detent torque as a returning force, and is 360 degrees / P. A light amount control device characterized in that the angular position is in the range of P>θ> 360 degrees / 2P. 3. A drive source having a pair of stator yokes, each of which has a plurality of magnetic poles and is arranged to face a rotor magnet made of a permanent magnet so as to form a gap, and the drive coil is wound around the drive source. In a light quantity control device having a light quantity control member driven by the drive source within a range of 360 degrees / P or less when the rotor magnet is magnetized to the number of poles P (an integer of 2 or more), the drive coil is A light quantity control device having a pair of excited main magnetic poles and a pair of non-excited auxiliary poles, the opening angles of which are all greater than 360 degrees / 2P. 4. The angle formed by the main pole and the supplementary pole according to claim 3, from the position of 360 degrees / 2P to the rotation direction side where the rotor magnet generates detent torque as a returning force. A light amount control device characterized in that the following angles are shifted. 5. A drive source having a pair of stator yokes, each of which has a plurality of magnetic poles and is arranged to face a rotor magnet made of a permanent magnet so as to form a gap, and the drive coil is wound around the drive source. In a light quantity control device having a light quantity control member driven by the drive source within a range of 360 degrees / P or less when the rotor magnet is magnetized to the number of poles P (an integer of 2 or more), the stator yoke is supplemented. Set up poles,
The angle formed by the main pole, which is a magnetic pole excited by the drive coil or a magnetic pole having a larger opening angle than the auxiliary pole, and the auxiliary pole is 360 degrees /
From the 2P position, the rotor magnet generates a detent torque as a returning force in the direction of rotation 360 degrees / 2P
Following along with shifting angle, the gap G _c of該補poles and the rotor magnet light quantity control device, characterized in that larger than the gap G _m of the main magnetic pole and the rotor magnet. 6. The light quantity control device according to claim 5, wherein the gap G _c of the auxiliary pole and the gap G _{m of the main} magnetic pole are 3 × G _m > G _c > G _m . 7. A drive source having a pair of stator yokes, each of which has a plurality of magnetic poles and is arranged to face a rotor magnet made of a permanent magnet so as to form a gap, and the drive coil is wound around the rotor magnet. One stator yoke in a light quantity control device having a light quantity control member driven by the drive source within a range of 360 degrees / P or less when the rotor magnet is magnetized to the number of poles P (integer of 2 or more) The opening angle of the main pole and the auxiliary pole formed in the main pole is larger, and in the gap G _m between the stator yoke thickness t _s and the rotor magnet length L _M rotor magnet and the main pole, L _f = ( _{L M -t s -2G m) /} 2 >> a 2 × G _m, the depth L of the cutout of the main magnetic pole and the interpole light quantity control device which is a L _f> L> G _m . 8. The opening angle of the main pole according to claim 7,
Greater than 60 degrees / 2P, the supplementary pole is smaller than 360 degrees / 2P, and the angle between the main pole and the supplementary pole is 360 degrees / 2P.
A light quantity control device characterized by being larger. 9. A drive source having a pair of stator yokes, each of which has a plurality of magnetic poles and is arranged to face a rotor magnet made of a permanent magnet so as to form an air gap, and the drive coil is wound around the drive source. At least one magnetic pole in a light quantity control device having a light quantity control member driven by the drive source in the range of 360 degrees / P or less when the rotor magnet is magnetized to the number of poles P (an integer of 2 or more) The light amount control device is characterized in that the side surface is asymmetric with respect to the other side surface with respect to the magnetic pole and is asymmetric with respect to the side surface of the adjacent magnetic pole. 10. The main pole and the auxiliary pole are formed in one stator yoke, and the opening angle of one of the magnetic poles is 36.
Greater than 0 degree / 2P, the opening angle of the other magnetic pole is 360 degrees /
2P or less, the angle formed by the main pole and the supplementary pole is larger than 360 ° / 2P, and a notch is formed on the side surface of the magnetic pole between the main pole and the supplementary pole, and the center of gravity of the notch is formed. Is a light quantity control device which is biased to the side of the commutating pole. 11. The surface according to claim 1, wherein the side surface of the magnetic pole passes through a center of a minimum gap between the differently excited magnetic poles of the pair of stator yokes, and is parallel to a plane including a rotation center axis of the rotor magnet. A light quantity control device characterized in that a portion inclined toward the magnetic pole opposite to the above is provided. 12. A rotor magnet made of a permanent magnet, having a plurality of magnetic poles arranged to face each other with an air gap formed therebetween,
A drive source having a pair of stator yokes around which a drive coil is wound, and a rotor magnet of the drive source have a pole number P (2
In the light amount control device having a light amount control member driven by the drive source in the range of 360 degrees / P or less when magnetized to the above integer), at least one of the magnetic poles of the pair of stator yokes is There is a notch, and one opening angle of the differently excited magnetic pole including the notch is larger than 360 degrees / 2P,
The other is smaller than 360 ° / 2P, and the opposite angle is 3 from the position of 360 ° / P in the direction opposite to the rotation direction in which the rotor magnet generates detent torque as a returning force.
A light amount control device characterized by being shifted by an angle of 60 degrees / 2P or less. 13. A plurality of magnetic poles, which are arranged to face a rotor magnet made of a permanent magnet with a gap therebetween,
A drive source having a pair of stator yokes around which a drive coil is wound, and a rotor magnet of the drive source have a pole number P (2
In the light amount control device having a light amount control member driven by the drive source in the range of 360 degrees / P or less when magnetized to the above integer), at least one of the magnetic poles of the pair of stator yokes is provided. The opening angle of the differently excited magnetic poles including the notch is 360 degrees / 2P or more, and the facing angle is a detent torque as a returning force of the rotor magnet from the position of 360 degrees / P. A light quantity control device characterized in that an angle of 360 ° / 2P or less is shifted to the side opposite to the direction of rotation in which it is generated. 14. A rotor magnet made of a permanent magnet, having a plurality of magnetic poles that are arranged to face each other with a gap formed therebetween,
A drive source having a pair of stator yokes around which a drive coil is wound, and a rotor magnet of the drive source have a pole number P (2
In the light amount control device having a light amount control member driven by the drive source in the range of 360 degrees / P or less when magnetized to the above integer), a pair of stator yokes excited by the drive coil A main magnetic pole and a pair of non-excited auxiliary poles are provided, and at least one of the main magnetic pole and the auxiliary magnetic pole has a notch, and the opening angles of the exciting magnetic pole and the non-excited magnetic pole including the notch are both 360. A light amount control device that is greater than degrees / 2P.