JPH0277733A - Stepping-motor driven diaphragm blade controller - Google Patents

Abstract

PURPOSE:To determine the aperture value of a diaphragm blade speedily and securely by exciting phase coils with out-of-phase pulses which are different from phase pulses and stopping a rotor at a desired frictional angle. CONSTITUTION:A clock pulse generating circuit 1 sends out a clock pulse phi0 which varies in pulse width within a frequency range of 300-1,000pps to 1st and 2nd phase pulse generating circuit 2. The circuit 2 generates mutually out-of-phase pulses phi1 and phi2 with pulse width phi0 in synchronism with the pulse phi0. A 4th phase pulse generating circuit 10 generates 4th phase pulses P1, P2, and P3 which do not synchronize with the pulse phi0 and differ in pulse width. A pulse switching circuit 3 sends out one necessary pulse to a driving unit 5 under the control of a CPU 21. Consequently, the phase coils are excited with out-of-phase pulses different from the phase pulse, so the rotor can be stopped at a desired frictional angle to determine the stop value of the diaphragm blade securely at high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an aperture blade control device for a camera, and more particularly to a stepping motor-driven aperture blade control device.

[Prior Art and Problems to be Solved] Conventionally, when driving the aperture blades of a camera using a stepping motor, it has not been possible to control the position of the aperture blades using a rotation angle in units of step angles of the stepping motor. The step angle is determined by the number of poles of the stator and rotor and the excitation force formula. If the step angle is small, the position of the aperture blades can be controlled to a desired position, but there is a drawback that the time required for this control becomes long.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems, and its purpose is to rotate the rotor at a unit step angle of the rotor or at an angle that is an integral multiple of the unit step angle with a unit cycle of excitation current. The first stepper motor rotates with an excitation current that is different from the unit cycle excitation current,
It is an object of the present invention to provide a stepping motor-driven aperture blade control device that can control the aperture blades at a minute angle of less than a unit step by sending the signal to the second phase coil.

[Means for Solving the Problems] In order to achieve the above object, a stepping motor aperture blade control device according to the present invention includes a stepping motor having a rotor, a stator, and first and second phase coils corresponding to the stator; The stepping motor-driven aperture blade control device includes an aperture blade driven by rotation of a rotor of the stepping motor, and includes a clock pulse generation circuit and third and fourth phase pulses generated by the clock pulse generation circuit. a third and fourth phase pulse generation circuit that generates the first and second phase pulses;
a pulse switching circuit that switches and outputs a fourth phase pulse;
Any one set of the first and second phase pulses and the third and fourth phase pulses switched by the pulse switching circuit is input, and first and second excitation currents are sent to the first and second phase coils. It is equipped with a drive unit.

[Embodiment of the Invention] An embodiment of a stepping motor-driven aperture blade control device according to the present invention will be described with reference to FIG.

The clock pulse generation circuit 1 has an operating frequency of 300 pps~
Clock pulse φ whose pulse width is variable to 1000pps
. is sent to the first and second phase pulse generation circuits 2. 1st
, the second phase pulse generation circuit 2 receives the pulse φ0 and generates the pulse φ. synchronized with and mutually one pulse φ. A first phase pulse φ1 and a second phase corus φ, which have a phase difference with a pulse width of , are generated (FIG. 5).

Further, the fourth phase pulse generation circuit 10 generates a pulse φ by a basic pulse generator 10a. not synchronized with and pulse φ.

The fourth phase pulses P1, P2, p with a pulse width different from
a (Fig. 5) is generated.

The first and second phase pulse/fourth phase pulse switching circuit 3 receives the first phase pulse φ input from the terminal T.

is sent to the terminal T6 of the drive unit 5 via the terminal T4. The first and second phase pulse/fourth phase pulse switching circuit 3 transfers the second phase pulse φ2 inputted from the terminal T2 from the terminal T to the terminal T7 of the drive unit 5 via the normally closed contact of the changeover switch 4. Send to. The drive unit 5 inputs the first phase pulse φ input from the terminal T6 to the first excitation current direction switching circuit 6. The first excitation current switching circuit 6 receives the first phase pulse φ from the terminals T8 and T9 of the drive unit soto 5 to the first phase coil 8.
Outputs excitation current. The current direction of the first excitation current is pulse φ. can be switched in synchronization with

The fourth phase pulse selection circuit 11 receives the fourth phase pulses P1, P2, and P8 generated by the fourth phase pulse generation circuit 10, and selects one of the phase pulses P1, P2, and P3 as the first,
Terminal T8 of second phase pulse/fourth phase pulse switching circuit 3
Enter. The first and second phase pulse/fourth phase pulse switching circuit 3 receives a fourth phase pulse P1 input to the terminal T,
One of P2 and P3 is input to the normally closed contact of the changeover switch 4.

The second excitation current direction switching circuit 7 receives the second phase pulse φ2 or the first and second phase pulses/fourth phase pulse input from the terminal T7.
When switched by the changeover switch 4 of the phase pulse switching circuit 3, a second excitation current is generated from any one of the fourth phase pulses P1, P2, and P8, and the generated second excitation current is transferred to the terminals T, . It is sent to the second phase coil 9 via ST, .

The rotor 12 of the stepping motor M (described later) is a first
Depending on the first and second excitation currents flowing through the phase coil 8 and second phase coil 9, the amount of aperture to be adjusted by the aperture blades 13a and 13 is determined.

CPU 214i operating frequency 300pps ~100
0pps (7) pulse φ. The clock generation circuit 1 is controlled to generate the clock.

Further, the CPU 21 receives one pulse φ. The first and second
Controls the phase pulse generation circuit 2.

Furthermore, this CPU 21 controls the first and second phase pulses/fourth phase pulse.
Controls the closing/opening of the changeover switch 4 of the phase pulse changeover circuit 3.

The CPU 21 also controls the first excitation current direction switching circuit 6 and the second excitation current direction switching circuit 7 of the drive unit 5 to determine the directions of the first excitation current and the second excitation current.

The directions of the first excitation current and the second excitation current are (+) direction excitation of terminals T8 to T9, TIG to T11, terminals T to 'F8, Tll to T, and so on. is excitation in the (-) direction.

As shown in FIG. 6(A), the magnetic poles 8a18b, 9a, 9b of the stators 8c, 9c excited by the first phase coil 8 and the second phase coil 9 have the direction of the first excitation current (-).
When the direction of excitation is directional, the stator 8a is the north pole, and when the direction of the second excitation current is (±) direction excitation, the magnetic pole 9b is the north pole.

Note that 25 is a shirt button, 26 is a power supply circuit, 22 is a ROM, 23 is a RAM, and 24 is a data bus. The shirt button 25 is a two-stroke switch, and the first stroke turns on the power circuit 26, calculates the aperture value, and turns on the aperture blade 13a.
, 13b, etc. In the second stroke, the operation sequence after the first stroke is executed, such as opening and closing of the shutter sector, flashing a strobe, and winding the film.

The first and second excitation current direction switching circuits 6.7 provided in the drive unit 5 will be explained with reference to FIG. 1st, 2nd
The excitation current direction switching circuit 6.7 includes inverters 6a, 7b,
Transistors 6b-6e.

7b to 7e, and terminals T8 to T8 from the drive unit 5.
First and second excitation currents switched to (+) direction excitation or (-) direction excitation are sent to the first and second phase coils via T11. In addition, the power supply ■. C is supplied from the power supply circuit 26 when the power supply circuit 26 is turned on.

The configuration of the aperture device of the aperture blades 13a and 13b will be explained with reference to FIG. A rotor pinion 35 interlocked with the rotor 12 of the stepping motor M is provided, and the rotor pinion 35 meshes with an idler wheel 47 to enable rotation transmission. The drive wheel 45 has teeth 45a that correspond to the idler wheel 4.
By meshing with the pinion wheel 41d coaxial with 7, the main plate 4
The rotating shaft 41 provided in 1. Rotate around a. The aperture blades 13a and 13b are pins 44a provided on the drive wheel 45.
The aperture value is determined by rotating around the pin 41b. Further, the driving wheel 45 has a degree determining portion 45b, which regulates the aperture value of the aperture blades 13a, 13b in relation to a pin 41c provided on the base plate 41.

Next, the stepping motor M will be explained with reference to FIG. The stepping motor M has a rotor 12 made of permanent magnets magnetized with four poles in the radial direction. Rotor 12
Magnetic poles 8a, 8b of two stators 8c, 9c of the same shape around which a first phase coil 8 and a second phase coil 9 are wound.

9a and 9b are facing each other. The lead wires of the first phase coil 8 and the second phase coil 9 are connected to the terminal T8 of the drive unit 5,
It is connected to T9, Tl0sT11.

Specifically, these stators 8c, 9c have a pair of legs so as to form a U-shape, and each end of the legs has magnetic poles 8a, 8b, 9a, opposing the outer periphery of the rotor 12. 9b
and each magnetic pole 8a.

8b, 9a, and 9b have an angle of 9 with respect to the center of the rotor 12.
They are formed to have a phase relationship of 0''.

The two stators 8c, 9c are on the same plane, and one of the magnetic poles 8b, 9b of the stators 8c, 9c is placed close to each other, and the phase relationship of the magnetic poles 8b, 9b arranged close to each other is set at an angle with respect to the center of the rotor 12. is arranged so that the angle is 45°. Furthermore, the magnetic poles 8a of each stator 8c, 9c,
First phase coil 8 that generates a magnetic field in 8b, 9a, 9b
, the second phase coil 9 is connected to each stator 8c, 9c, respectively.
The legs are inserted into the legs on the side opposite to the magnetic poles 8b and 9b arranged close to each other, that is, on the side of the magnetic poles 8a and 9a.

[Operation of the Invention] In the stepping motor-driven aperture blade control device having the above configuration, the reflock pulse generation circuit 1 is controlled by the CPU 21, and the clock pulse φ is controlled by the CPU 21. The pulse width is, for example, a frequency of 1000 pps. The first and second phase pulse generation circuits 2 generate clock pulses φ under the control of the CPU 21. clock pulse φ. has a first pulse width equal to the pulse width of
and one pulse φ to each other. The first phase col 8 has a phase difference of
φ□, position excluding the corresponding position (curvature point) (at time of ts)
Then, a second pulse width (third pulse width) different from the first pulse width is used.
The phase pulse is L (0) level) and the fourth phase pulse P1,
P2 and P3 are generated, pulse P is a pulse with a duty of 50%, P2 is a pulse with a small second pulse width for excitation in the (+) direction, and P8 is a pulse with a small second pulse width for excitation in the (-) direction. shall be.

In the first and second phase pulse/fourth phase pulse switching circuit 3, the changeover switch 4 is placed on the normally closed contact side as shown in FIG. 1 under the control of the CPU 21. In this state, the first and second phase pulse/fourth phase pulse switching circuit 3 sends out the first phase pulse 8φ inputted from the terminal T to the terminal T6 of the drive unit 5 via the terminal T4, and The second phase pulse φ2 inputted from the switch 4 is sent from the terminal T to the terminal T7 of the drive unit 5 via the normally closed contact of the changeover switch 4. The drive unit 5 inputs the first phase pulse φ1 input from the terminal T6 to the first excitation current direction switching circuit 6, and inputs the second phase pulse φ2 input from the terminal T7 to the second excitation current direction switching circuit 7. . The first phase pulse φ1 is input to the first excitation current direction switching circuit 6 and the second excitation current direction switching circuit 7 of the drive unit 5, and the terminal T6
, T, outputs the first excitation current to the first phase coil 8,
A second phase pulse φ2 is input, and a second excitation current is output from the terminals T, . . . to the second phase coil 9. Figure 5 (
As shown in 1), the current directions of the first excitation current and the second excitation current are t. At this point, the first phase coil 8 is excited in the (-) direction, and the second phase coil 9 is excited in the (+) direction.

At time t1, the first phase coil 8 remains excited in the (-) direction,
The second phase coil 9 is excited in the (-) direction, and the rotor 12 starts rotating from FIG.
At time point 2, the first phase coil 8 is excited in the (+) direction, the second phase coil 9 is still excited in the (-) direction, and the rotor 12 is as shown in FIG.
It rotates from C) to (D) and then to (E), ending the 45° rotation here (#1. 2-phase excitation, Fig. 5). Next, #2.2
When phase excitation is performed, the current direction of the first excitation current of the first phase coil 8 and the second excitation current of the second phase coil 9 is t. It will be the same as the point in time.

Note that when the rotor 12 rotates, the rotor pinion 35 (FIG. 3) rotates, the idler wheel 47 rotates, and the adjustment portion 45b of the drive wheel 45 moves to a predetermined position, and based on this amount of movement, the aperture blade 13 a , 13b are driven.

The fourth phase pulse generation circuits 1 and 0 are controlled by the CPU 21 and generate a fourth phase pulse P with a duty of 50% using the pulses generated by the basic pulse generator 10a. This fourth phase pulse P1 is inputted to the terminal T3 of the first and second phase pulse/fourth phase pulse switching circuit 3 via the fourth phase pulse selection circuit 11 under the control of the CPU 21. The fourth phase pulse switching circuit 3 is operated by the switching switch 4 under the control of the CPU 21.
is on the normally open contact side opposite to that shown in FIG.
The excitation current is applied to the second phase coil 9 via the direction switching circuit 7. When the fourth phase pulse P is applied to the second phase coil 9 at time t6 after time t4 in FIG.
As shown in B), the magnetic pole 8b of the stator 8c is the north pole, the magnetic pole 9a of the stator 9c is the north pole, the rotor 12 rotates by half (θ/2) of the unit step angle θ (45°), and at t5
At this point, it rotates 112.5 degrees. 1 after time t2 in Figure 5. When the fourth phase pulse P is applied to the second phase coil 9 at this point, as shown in FIG. 7(A), the magnetic pole 8b of the stator 8c is the S pole, the magnetic pole 9a of the stator 9c is the N pole, The rotor 12 is half (θ/2) of the unit step angle θ (45°).
) rotates. In this case, Fig. 5 #2.2 phase excitation is not performed, and the operation at time t5 is carried forward to time 13, and
At this point, it rotates 67.5 degrees.

The fourth phase pulse generation circuit 1 is controlled by the CPU 21.
When a fourth phase pulse P2 with a small pulse width of the excitation current in the 0 to (+) direction is generated, this fourth phase pulse P2 is passed through the fourth phase pulse selection circuit 11 under the control of the CPU 21 to the first, The current is applied from terminals T3 and T6 of the second phase pulse/fourth phase pulse switching circuit 3 to the second phase coil 9 via the second excitation current direction switching circuit 7 of the drive unit 5. In this case, the magnetic pole 8b of the stator 8C is the north pole, and the magnetic pole 9a of the stator 9C is the south pole (after time t4 in Figure 5), and as shown in Figure 8(B), the rotor is rotated at an angle of (θ/2) + α. 12 rotates. After time t2 in FIG. 5, the rotor 12 rotates at an angle of (θ/2)+α as shown in FIG. 8(A), and at time t3, it rotates by 67.5°+α.

When the fourth phase pulse P3 with a small pulse width of the excitation current in the (-) direction is generated from the fourth phase pulse generation circuit 10 under the control of the CPU 21, this fourth phase pulse P3
is the fourth phase pulse selection circuit 11 under the control of the CPU 21.
The excitation current is applied from the terminals T3 and T5 of the first and second phase pulse/fourth phase pulse switching circuit 3 to the second phase coil 9 via the second excitation current direction switching circuit 7 of the drive unit 5. In this case, the magnetic pole 8b of the stator is the N pole, and the magnetic pole 9
When a is the south pole (time t4 in FIG. 5), the rotor 12 rotates at an angle of (θ/2)−α as shown in FIG. 9(B).

At time t2 in Fig. 5, as shown in Fig. 9 (A), (θ/2
) - α, the rotor 12 rotates at an angle of 67 at time t3.
．． At a rotation of 5°-α (at time ts), the third phase pulse is changed to (-
) direction excitation to the L(0) level; however, the third phase pulse was used, and furthermore, in the above embodiment, two-phase excitation was used.The stepping motor-driven aperture blade control device of the present invention may also be one-phase excitation.

Further, in the first embodiment, the aperture blade control device driven by a stepping motor of the present invention is not limited to this, and may be driven by unipolar drive.

[Effects of the Invention] As is clear from the above embodiments, the stepping motor aperture blade control device according to the present invention includes a stepping motor having a rotor, a stator, and first and second phase coils corresponding to the stator; In the stepping motor-driven aperture blade control device comprising aperture blades driven by the rotation of the rotor of the stepping motor, a clock pulse generating circuit and a first clock pulse generating circuit having a phase difference in pulse width; a third = 17-fourth phase pulse generation circuit that generates third and fourth phase pulses with a second phase pulse width; A pulse switching circuit to output, and any one set of the first and second phase pulses and the third and fourth phase pulses switched by the pulse switching circuit are input to the first and second phase coils.
, and a drive unit that sends out the second excitation current, the plurality of phase coils are excited with a non-phase pulse different from the phase pulse, so the rotation speed is reduced by 1/2.
Since the rotor can be stopped at a desired fractional angle without using the phase excitation method, it can be used to determine the aperture value of aperture blades that require a large rotation angle while maintaining high speed and stable torque to reliably drive the aperture blades. can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a stepping motor-driven aperture blade control device according to an embodiment of the present invention, FIG. 2 is a circuit diagram of the drive unit shown in FIG. 1, and FIG. 3 is a configuration diagram of the aperture device shown in FIG. 1. , FIG. 4 is a configuration diagram of the stepping motor shown in FIG. 1, FIG. 5 is a time chart of pulses applied to the stepping motor shown in FIG. 1, and FIG. 6 (A).
(B), (C), '(D), (E), Figure 7 (A), (
B), FIGS. 8(A) and (B), and FIGS. 9(A) and (h) are operation diagrams showing the rotation of the rotor shown in FIG. 1. 1... Clock pulse generation circuit 2... First and second phase pulse generation circuit ・3...
-First and second phase pulse/fourth phase pulse switching circuit 5...Drive unit 8...First phase coil 9...Second phase coils 8c, 9c...Stator 10... ...Fourth phase pulse generation circuit 12...Rotors 13a, 13b...Aperture blades M...Stepping motors Pl, P2, P3...Fourth phase pulse φ.・・・・・・
Clock pulse φ,...First phase pulse φ2...Second phase pulse Fig. 6 Fig. 7

Claims (1)

[Claims] a rotor, a stator, and a first corresponding to the stator;
In a stepping motor-driven aperture blade control device comprising a stepping motor having a second phase coil and aperture blades driven by rotation of a rotor of the stepping motor, a clock pulse generation circuit and a clock pulse generation circuit generate a clock pulse. a first clock pulse corresponding to a stop position of the stator and the rotor;
first and second phase pulse generation circuits that generate first and second phase pulses having a phase difference with each other with a pulse width of
a third and fourth phase pulse generation circuit that generates a fourth phase pulse; a pulse switching circuit that switches and outputs the first and second phase pulses and the third and fourth phase pulses; and the pulse switching circuit. a drive unit that receives one set of the switched first and second phase pulses and the third and fourth phase pulses and sends out first and second excitation currents to the first and second phase coils. A stepping motor-driven aperture blade control device.