JPH0474693B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an operation control device for a step motor used, for example, to operate a sector of a camera shutter.

[Prior Art] Step motors have traditionally been used to drive sectors of cameras, but these step motors are composed of a radially magnetized rotor, a plurality of stators, and coils, and receive pulse signals. A gear mechanism is used as means for transmitting the rotation of the step motor to the sector, and a spring is provided to bias the sector in the closing direction. In addition, in a step motor, if the phases of the magnetic poles of the rotor and stator are out of phase, the rotor may not synchronize with the pulse signal, the rotor's responsiveness to the pulse signal may change, or the rotor may rotate in the opposite direction. The phase relationship between the magnetic poles of the rotor and stator is important because it can cause abnormal operation.

[Problem to be solved] By the way, if a large external force or impact is applied to the camera, there is a risk that the phases of the magnetic poles of the rotor and stator will be out of phase. In both cases, when the sector opens and then closes, the inertial movement of the sector, gear mechanism, rotor, etc. in the return direction causes an impact to hit the adjustment part and its regulating member, and the repulsion causes the sector to operate in the opening direction again. There is a risk that the sector may reopen and become re-exposed.

Further, even if there is no restriction such as a degree determining part in the closing direction of the sector, the inertial movement may cause the rotor's stopping position to deviate from a predetermined position, causing the magnetic poles of the rotor and stator to be out of phase.

SUMMARY OF THE INVENTION An object of the present invention is to provide a step motor operation control device that prevents sectors from opening again when they are closed.

[Means for Solving the Problems] The feature of the present invention is that after the step motor is operated,
The drive coils are continuously energized with long pulses of the same phase, applying magnetic attraction or repulsion to the rotor through each stator, and forcibly holding the rotor for a predetermined period of time. This is to prevent the recoil of the drive member.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

1 and 2 show the configuration of a step motor section M, in which a roller 1 consisting of a permanent magnet magnetized with four poles in the radial direction is fixed to a rotor shaft 2. FIG. As shown in the second figure, the lower end of the rotor shaft 2 is rotatably supported by a hole in a lower plate 3, and the upper end thereof is rotatably supported by a hole in an upper plate 4. The lower end of the rotor shaft 2 passes through a hole in the lower plate 3, and a rotor pinion 5 is fixed to the tip thereof, and this rotor pinion transmits the rotation of the rotor 1 to the gear train.

The two stators 6, 6 having the same shape are U-shaped as shown in the first diagram, and have a pair of legs, and each end of the legs has a 4-inch stator facing the outer periphery of the rotor 1. The magnetic pole parts 6a of each stator 6 are positioned so that the angle α with respect to the center of the rotor 1 is 90°. In addition, two stators 6, 6
are on the same plane, and the magnetic pole portions 6a of the stator are placed close to each other, and the phase relationship of the magnetic pole portions 6a placed close to each other is such that the angle β with respect to the center of the rotor 1 is 45°, Its position is determined by a guide pin 3a provided on the lower plate 3. Therefore, the stator 6,6
are opposed to the magnetic poles of the rotor 1 with a predetermined deviation angle.

Furthermore, the magnetic pole parts 6a, 6a of each stator 6, 6
The two coils 7a and 7b that generate a magnetic field are
The coils 7a and 7b are connected to the drive circuit 9, and are wound around coil frames 8 and 8, respectively.
It is inserted into the leg part on the side other than the magnetic pole part 6a, which is arranged close to each other at an angle β.

The lower plate 3 and the upper plate 4 are formed by plastic molding, and the lower plate is integrally formed with a locking claw 3b for attaching and fixing the upper plate 4. The guide pin 3 of the lower plate is attached to the plate 4.
A guide hole 4a that fits into the guide hole 4a and a hook portion 4b that engages with the locking claw 3b are integrally formed.

After the two stators 6 and the rotor 1 into which the coils 7a and 7b are inserted are attached to the lower plate 3, the upper plate 4 is placed from above, and the locking claws 3b
By engaging the hook portion 4b, the lower plate 3
The upper plate 4 and stator 6 are fixed, and the rotor 1
is rotatably supported.

Next, FIGS. 3 and 4 show the configuration of a gear train section and a sector section operated by a step motor M.
(Fig. 4) is attached with screws. An aperture O for a lens aperture is formed at the center of the base plate 11 and base plate 12, and a sector chamber R (FIG. 4) for storing a sector 13, which will be described later, is formed between them. Sector drive lever 14
is rotatably supported by a rotating shaft 11a provided on the base plate 11, and is supported by the lower surface of the step motor M so as not to slip out.

The sector drive lever 14 has a sector drive wheel 15.
is rotatably attached, and a groove 14b provided on this sector drive lever engages with an engagement pin 16 fixed to this sector drive wheel, thereby restricting the relative rotation of both 14 and 15. .

Further, the sector drive lever 14 is provided with a sector pin 14a, which is connected to the main plate 1.
1 and engages with the groove of the sector 13.
Further, the sector 13 is rotatably supported by a pin 11b provided on the base plate 11, and the opening O
It is configured to determine.

The sector drive wheel 15 attached to the sector drive lever 14 is integrally formed with a gear 15a, and is further provided with a degree determining portion 15b and a pin 15c. The gear 15a is meshed with the pinioca portion 17a of the idler wheel 17, and the determining portion 1
5b is restricted from rotating by coming into contact with a pin 11c provided on the base plate 11, and the pin 15c engages with a spring 19 and is biased counterclockwise by this spring. The biasing force of the spring 19 is to bias the clearance of the rotary support part of the step motor M from the rotor pinion 5 to the sector drive lever 14, the backlash of the meshing part, etc. The torque is appropriately set within a range that is less than the current holding torque (torque held by the magnetic coupling force between the rotor and stator when no current is applied to the coil) and is sufficient to eliminate the above-mentioned play.

The means for fixing the engaging pin 16 to the sector drive wheel 15 is by caulking the sector drive wheel or the like.

The idler wheel 17 includes a pinion portion 17a (FIG. 4) that meshes with the tooth portion 15a of the sector drive wheel 15,
It has a tooth portion 17b that meshes with the rotor pinion 5, is rotatably supported by a rotating shaft 11d provided on the base plate 11, and is supported by the lower surface of the step motor M so as not to come off.

Further, a pillar 11e for attaching a step motor M is integrally formed on the main plate 11.
When the step motor M is fixed to this column with a set screw 18 (FIG. 4), the rotor pinion 5 and the idler wheel 17 mesh with each other, making it possible to transmit rotation.

Furthermore, FIG. 5a shows two coils 7a and 7b.
(Fig. 1) and generates a predetermined magnetic field in each magnetic pole portion 6a of the stators 6, 6.
This is a drive signal of a known bipolar drive two-phase excitation method in which the directions of the excitation current of the coil are positive (+) and negative (-), and the excitation current is constantly flowing through two coils. It is. In addition, this drive signal corresponds to photometric information and distance information of the subject. For example, if the brightness of the subject is dark, the number of excitation pulses for the coil is increased, and if it is bright, the number of excitation pulses is decreased. This will be decided as appropriate. Furthermore, FIG. 5b is an opening operation diagram of the sector 13 when driven by the pulse shown in FIG. 5a.

Furthermore, when the coil 7 of the step motor M configured as described above is energized, the position where the rotor 1 stops due to the magnetic field generated in the magnetic pole portions 6a of the stators 6, 6 is the NS pole of the rotor 1 in FIG. is Y
On the axis, on a line parallel to the X-axis, and with respect to the X-axis
When it is on a straight line at 45 degrees, there are 8 locations per rotation for every 45 degrees. In addition, when the NS pole of the rotor 1 is on the Y-axis or on a line parallel to the X-axis at the eight stopping positions mentioned above, there is a possibility that the magnetic coupling force with the magnetic pole part 6a will be balanced and the rotor will stop even when not energized. Although there is
It is difficult to stably stop on the above-mentioned axis due to manufacturing errors of each part, clearance of fitting parts, vibration, etc.

Therefore, when the coil 7 is de-energized, the rotor 1
The position at which the rotor 1 stops due to the balance of the magnetic coupling force between the NS pole of At some point, there will be four locations per rotation for every 90 degrees.

In a state where the rotation in the counterclockwise direction is restricted as shown in FIG. 3 by the contact between the degree determining part 15b of the sector drive wheel 15 and the pin 11c of the main plate, the position of the rotor 1 is changed when no power is applied. The rotor pinion 5, idler wheel 17 and sector drive wheel 15
The gears are meshing.

Therefore, the operation of the present invention will be explained.

First, when the two coils 7a and 7b are not energized, the magnetic coupling force between the four magnetic pole portions 6a of the two stators and the four NS poles of the rotor 1 and the configuration of the magnetic pole portions 6a cause the rotor 1 to There are four statically stable stopping states per revolution, and the motor is stopped in the state shown in Figure 6a.
Further, the sector drive wheel 15 is also in a position where the rotation determining portion 15b and the pin 11c are in contact so that the rotation in the counterclockwise direction is restricted, and the two sectors 13 that are engaged with the pin 14a of the sector drive lever 14 are also , the lens opening O is in a state of being closed.

In this state, the camera's release means, photometry means, etc. (not shown) operate, and the output signal of the drive circuit 9 is determined as shown in FIG. coil 7
A and 7b are energized, and opening/closing operations of the sector are performed as described below.

First, the first excitation pulse energizes the magnetic pole portions 6a of each stator to generate a magnetic field as shown in FIG. 6b, in order to further forcibly maintain the statically stable position of the rotor 1. This is to prevent this, because if a large external force or impact is applied to the camera and this stop position is no longer guaranteed, the phases of the magnetic poles of the rotor 1 and stator 6 will be out of alignment, causing problems with the exposure performance of the shutter. Therefore, it is an excitation pulse that corrects the stopping position of the rotor 1 so as to return it to a predetermined position as shown in FIG. 6a.

Next, when the coil 7a side is energized with a second pulse, which is the same as the first pulse but the current on the coil 7b side is reversed, a magnetic field as shown in Fig. 6c is generated, and the rotor 1 rotates clockwise. The rotor 1 starts to move and rotates 45 degrees to the position of the rotor 1 shown in FIG. 6d. The rotation of rotor 1 is
The signal is transmitted to the sector 13 by the rotor pinion 5, idler wheel 17, sector drive wheel 15, and sector drive lever 14, and the sector 13 starts opening operation.

When the third pulse is energized, the coil 7b side becomes 2
At the same time as the first pulse, the current on the coil 7a side is reversed,
A magnetic field as shown in FIG. 6d is generated, the rotor 1 further rotates 45 degrees clockwise, and the sector 13 actually begins to open.

The next 4th pulse generates a magnetic field as shown in Fig. 6 e-1, and the rotor 1 further rotates clockwise to the state shown in Fig. 6 e-2.
When the current on the coil 7b side is reversed for the fourth pulse by the energization of the pulse, a magnetic field as shown in FIG. Start.

The closing operation of the sector 13 is performed sequentially by the excitation of the 6th pulse in FIG. 6g and the 7th pulse in FIG. They come into contact and are in the same position as before activation.

By the way, sector 13, sector drive lever 1
4. Due to the inertial movement of the sector drive wheel 15 in the return direction, the determining portion 15b of the sector drive wheel impacts against the pin 11c, and the sector 13 tries to operate in the opening direction again due to the repulsion, but the 8th pulse Figure 6 i
By energizing the rotor 1 as shown in FIG. 1, the rotor 1 is continuously held at the stop position where the determining portion 15b and the pin 11c are in contact with each other, and abnormal reaction motion due to the repulsion of the sector 13 is restricted.

Thereafter, the power to the two coils 7a and 7b is removed, the rotor 1 stops at the initial position shown in FIG. 6a, and the operation of the camera ends.

In the above operation explanation, the pulse is reversed from the 4th pulse to the 5th pulse to reverse the rotor 1. However, the timing of this reverse pulse is different when the subject is bright due to photometry or distance information, or when the subject is close-up when using a strobe. When photographing, it is programmed to reverse at a position with a small number of pulses, and when the subject is dark or when photographing from a distance, even when using a strobe, it is programmed to reverse at a position where a large number of pulses are required. In addition, in the above embodiment, the sector drive wheel 15 pin 11c is used to regulate the holding torque of the step motor M when it is not energized.
By setting the biasing force of the spring 19 to be sufficiently small, the biasing direction of the spring can be reversed, or the biasing force of the spring 19 can be reversed.
c can be omitted. In this case as well, by applying electricity in the same way as in the above embodiment before and after the sector operation, phase shifts due to inertial motion of each member can be prevented after the sector operation.

Furthermore, in FIG. 5, the first pulse before the sector operation and the eighth pulse after the sector operation are applied to the step motor This may be done as appropriate, such as increasing the current to the coil or increasing the pulse width.

[Effects of the Invention] According to the present invention having the above configuration, when the drive member, for example, the sector, closes after the step motor is operated, continuous long pulses of the same phase are energized to the coil, thereby causing the inertial movement of each member, etc. It is possible to prevent the rotor from shifting from its predetermined position by correcting it, thereby reliably preventing reaction such as the drive member opening again, and also to ensure that the initial position of the rotor is accurate. do.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a step motor used in the present invention, FIG. 2 is a sectional view of FIG. 1, FIG. 3 is a plan view of a sector opening/closing section driven by the step motor according to the present invention, and FIG. 3 is a sectional view of FIG. 3, FIG. 5 is a waveform diagram of an output signal from the drive circuit and a sector opening operation diagram, and FIGS. 6 a to 6 i are operation diagrams of the step motor. 1... Rotor, 6, 6... Stator, 7a, 7
b... Coil, 9... Drive circuit, 13, 13...
Drive member (sector), 14... sector drive lever,
15... Sector drive vehicle, O... Lens aperture, M...
...Step motor.

Claims (1)

[Scope of Claims] 1. A permanent magnet rotor having a plurality of magnetic poles, a sector drive member operated by the rotor, a regulating member that regulates a stop position of the drive member, and a sector drive member that regulates a stop position of the drive member; In a step motor for a shutter, the step motor is constituted by a plurality of stators having a plurality of magnetic pole parts facing each other with a deviation angle of , and a drive coil wound around each of the stators and connected to a drive circuit, The drive circuit continues to energize the drive coil with long pulses of the same phase even after the step motor has moved the drive member to the stop position, and the energization causes the stator to pass through the stator. 1. An operation control device for a step motor for a shutter, characterized in that the rotor is forcibly held for a predetermined period of time by applying magnetic attraction or repulsion to the rotor to prevent reaction of the drive member.