JPS63133884A - Constant-speed controller - Google Patents

Abstract

PURPOSE:To prevent the operation timing from being displaced or the position controlling accuracy from decreasing by controlling the exciting time of a motor so that the counterelectromotive force of the motor at the time of deenergizing the motor becomes constant. CONSTITUTION:A microprocessor unit (MPU) 11 controls a motor 14 and a combination solenoid 21 through a motor driver 12 and a combination solenoid driver 20 on the basis of the signal inputs from an analog/digital converter 16, a timing switch 18, and a phase sensor 19. The driver 12 drives the motor 14 while turning ON, OFF a power source 13 by a command from the MPU 11. The MPU 11 samples the terminal voltage Vm when the motor is OFF through the converter 16, and controls the duty of a command signal to the driver 12 so that the value of the counterelectromove force becomes constant.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a constant speed control device that keeps the rotational speed of a motor constant regardless of variations in power supply voltage or load.

(Prior art) The rotational speed of a motor fluctuates depending on fluctuations in power supply voltage and load. However, in various devices that use a motor as a drive source, variations in the speed of the motor may cause various inconveniences.

For example, some cameras use a motor to perform a series of operations such as driving an aperture, setting a shutter, and raising and lowering a mirror. In such a camera, if the rotational speed of the motor fluctuates, problems such as a shift in the timing of the start of photometry and other series of operations, and a decrease in the accuracy of controlling the position of the aperture lever occur.

(Purpose) The purpose of the present invention is to control constant speed control, which prevents deviations in the timing of a series of operations of equipment driven by the motor and a decrease in position control accuracy by controlling the rotational speed of the motor to a constant value. The goal is to provide equipment.

(Configuration) As shown in FIG. 1, the present invention includes a motor control section 1 that drives the motor 14 while controlling excitation of the motor 14 on and off, and a motor control section 1 that drives the motor 14 while controlling excitation of the motor 14 on and off;
The motor controller 1 has a back electromotive voltage detection section 2 that detects a back electromotive voltage of It is characterized by controlling the on time.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a constant speed control device according to the present invention is applied to a camera will be described below with reference to the drawings. 2 shows an outline of a camera having the device of the present invention. Second
In the figure, a microprocessor unit (rMP
(referred to as UJ) 11 is an analog-to-digital converter 16;
Based on input signals from the timing switch 18 and position sensor 19, the motor 14 and combination solenoid 21 are controlled through the motor drive circuit 12 and combination solenoid drive circuit 20. The motor 14 drives the aperture, shutter, and mirror of the camera, as will be explained in detail later, and its back electromotive voltage Vm is applied to the MPU 1l through the multiplexer 15 and the analog-to-digital converter 16. A voltage from a timing adjustment resistor 17 is also applied to the MPU II through a multiplexer 15 and an analog-to-digital converter 16.

The timing switch 18, position sensor 19, and combination solenoid 21 will be explained later.

Reference numeral 13 is a power source for driving the motor 14.

FIG. 6 shows a block diagram of the mechanism driven by the motor 14. In FIG. 6, the rotational force of the motor 14 is decelerated by a speed reduction device 24 and then transmitted to a mirror cam 25, an aperture cam 36, and a shutter cam 38, and the aperture cam 36 drives an aperture lever 46 on the camera side.

After the movement of the aperture lever 46 is accelerated by the speed increase mechanism 30, when it reaches a predetermined position, this is detected and the stop mechanism 31 stops the speed increase mechanism 30 and controls the aperture lever 46 to a predetermined position. The aperture lever 46 is linked to the aperture lever 57 on the lens side.
to a predetermined position.

FIG. 9 shows the aperture cam 36, shutter cam 38, aperture lever 46, and the surrounding mechanisms. In Figure 9,
The gear 33 is rotationally driven by the motor 14, and the gear 33 rotationally drives the cam gear 34. The cam gear 34 is integrally provided with an aperture cam 36 and a shutter cam 38. A lever 40 is provided on the side of the aperture cam 36 so as to be rotatable about a shaft 41. lever 40
has a cam follower 42. One end of a connecting lever 44 is pivotally attached to the lever 40, and a pin 48 of an aperture lever 46 is fitted into a long hole 45 formed at the other end of the connecting lever 44. The aperture lever 46 is formed in the shape of a bell crank and can rotate about a shaft 47 in a plane parallel to the rotation plane of the lever 40 . The aperture lever 46 and the lever 40 are biased toward each other by an aperture biasing spring 53. A tip 49 of the aperture lever 46 is in contact with an aperture lever 57 on the lens side. The aperture lever 57 is biased to follow the aperture lever 46 on the camera side.

The bending portion 50 of the aperture lever 46 comes into contact with a stopper 55, so that the clockwise rotation in FIG. Rotation is restricted. Aperture lever 4
6 is also formed with another bent portion 51, and this bent portion 5
1 is in contact with a roller 58.

FIG. 7 shows the construction of a speed increasing mechanism and a stop mechanism that are linked to the aperture lever 46 through the roller 58.

In FIG. 7, the roller 58 is provided on a lever 77 whose rotation center is a shaft 78 and whose one end edge constitutes a fan-shaped gear 79. The rotational force of the sector gear 79 is transmitted to the ratchet wheel 85 via the speed increasing gear train 80, 81, 82, 83,
The ratchet wheel 85 is rotated at high speed. An encoder disk 86 having a large number of slits 87 at regular intervals in the circumferential direction is integrally attached to the ratchet wheel 85.

Photo ink printers 88 are installed to sandwich both sides of the encoder disk 86. The photo ink converter 88 detects the light transmitted through the slit 87 of the encoder disk 86 and outputs a signal, and corresponds to the position sensor 19 in FIG. 2.

By counting this output signal, the rotation amount of the claw table 85,
Furthermore, the amount of rotation of the aperture lever 46 can be detected.

In FIGS. 7 and 8, a claw 91 is opposed to the outer periphery of the claw group 85. As shown in FIG. Claw 91 is combination solenoid 9
0 to control the rotational position, the combination solenoid 9o is in an excited state,
Furthermore, due to the de-energized state, the claw 91 is driven in the direction of engagement with the windmill 85, and the claw 91 is also driven in the direction of separation from the windmill 85.

The combination solenoid 90 is driven by the old MPU II through the drive circuit 20 (see FIG. 2), and when the aperture lever 46 reaches a predetermined rotational position, the combination solenoid 90 is moved by its pawl The position of the aperture lever 46 is determined by driving it so that it moves in a direction in which it engages with the windmill 85. The specific configuration of the combination solenoid 90 will be described later.

In FIG. 9, a cam follower 62 provided on a shutter center lever 60 is in contact with the shutter cam 38. The shutter release lever 60 is rotatable around a shaft 61, and when it is rotated clockwise in FIG. 9, a pin 63 provided at the end of one arm pushes up the shutter charge lever 64 and centers the shutter. .

In FIG. 9, a gear 66 is meshed with the cam gear 34. A base of a brush 67 is fixed to the gear 66. The brush 67 is in sliding contact with the conductive pattern shown in FIG. 10, and the timing switch 1 shown in FIG.
8. The conductive pattern in FIG. 10 consists of three conductive patterns 68, 69, and 70, and these conductive patterns are arranged in the above order from the outer circumferential side. The conductive pattern 68 constitutes the first switch SWI, and the conductive pattern 69 constitutes the second switch SW2. The conductive pattern 70 forms a common contact of the conductive patterns 68 and 69.

The brush 67 is connected to the three conductive patterns 6B, 69.70
The switches SWI and SW2 are turned on and off depending on the rotational position. switch S
WI and SW2 are timing switch 1 in Fig. 2.
8.

The brush 67 shown by the chain line in FIG. 9 is in the home position 71, and the switches SWI and SW2 are both on. When the brush 67 rotates clockwise in FIG. 10, switches SWI and SW2 are both turned off, and when the aperture count start position 72 is reached, switch S is turned off.
WI is turned on. When the brush 67 further rotates, the switch SWI is turned off, and when it reaches the stop-down end position 73, the switch SW2 is turned on. When the brush 67 rotates further, the switch SW2 is turned off, and when the brush 67 reaches the mirror-up start position and the re-metering start position 74, the switch SW2 is turned off.
turns on. When the brush 67 rotates further, the switch SWI turns off and the brush 67 returns to the home position 7.
When the mirror-up end position 75 is reached after rotating approximately 180 degrees from 1, the switch SW2 is turned on. Just before the brush 67 further rotates clockwise and reaches the home position 71, the switches SWI and SW2 are both turned off, and then the home position 71 is reached.

FIGS. 11 and 12 show specific examples of combination solenoids, and show examples of monostable combination solenoids. A movable core 94 is provided inside the coil 93 and is rotatable about a shaft 97.
1 is formed. The coil 93 forms an S pole and a N pole on the upper and lower sides, and attracts the movable iron core 94 with a pair of attracting plates 95,95. There is one magnet 92 outside the coil 93. The magnet 92 has an S pole and an N pole formed in the thickness direction, that is, in the inner and outer directions. Before the coil 93 is energized, only the magnetic field by the magnet 92 exists, and the movable iron core 94 is attracted to the magnet 92 side. Next, when the coil 93 is energized, a magnetic field is generated in the coil 93. This magnetic field interacts with the magnetic field emitted from the magnet 92, producing parts with low magnetic flux density and parts with high magnetic flux density. In FIG. 12, the magnetic flux density at a portion indicated by reference numeral 98 becomes smaller, and the movable core 94 rotates in the direction of larger magnetic flux density as shown in FIG. 11. When the coil 93 is de-energized, the movable core 94 is returned to its original position by the magnet 92.

Figures 13 and 14 show examples of bistable combination solenoids. In FIGS. 13 and 14, the coil 9
Magnets 96 and 96 having S and N poles formed in the inner and outer directions are arranged on both sides of the magnet 30. Now, when the coil 93 is energized to form S and N poles at the top and bottom of the coil 93, a portion 99 with high magnetic flux density is generated between the magnet 96 on one side and the coil 93, and the upper magnet 96 and the coil 93 A portion 100 with a low magnetic flux density is generated between the movable iron core 94 and the movable iron core 94, as shown in FIG. If the direction of energization to the coil 93 is reversed, the portions with high and low magnetic flux densities will be reversed, and the movable iron core 94 will rotate in the opposite direction. When the coil 93 is de-energized, the movable core 94 maintains its current rotational position.

FIG. 15 shows an example of a drive circuit for a bistable combination solenoid, in which the coil 93 can be bidirectionally energized by drive elements such as bridge-connected transistors. Each transistor is controlled by a solenoid control device such as the MPU 11 shown in FIG.

Next, the operation of the above embodiment will be explained with reference to FIGS. 16 to 18.

Here, a bistable type is used as the combination solenoid 90, and when the operation starts, the combination solenoid 90 is first energized and the pawl 91 is placed in a standby position where it is separated from the mold wheel 85. When the release is released in this state, the motor 14 starts rotating in the forward direction, the aperture cam 36 is rotationally driven, the aperture lever 46 rotates, and the lens-side aperture lever 57 starts moving (Fig. 16C
reference). The brush 67 is driven as the motor 14 rotates, and when it reaches the aperture count start position 72, the sui-nochi SWI
turns on and aperture counting starts. The aperture count is performed by counting the detection pulses of the photo ink club 88, and when a predetermined aperture count value is reached, the combination solenoid 90 is energized in the opposite direction to close the claw 9.
1 is engaged with the mold wheel 85, and the rotation of the mold wheel 85 is stopped, thereby stopping the movement of the aperture lever 46. The predetermined aperture count value is calculated based on the photometric value.

Here, the encoder disk 86 is rotationally driven via a speed-increasing gear train, and due to mechanical rattling between the two, as shown by the symbol t in FIG. Since the detection pulse is output from the photo ink club 88 with a timing delay, the timing of starting counting of the detection pulse is shifted accordingly. The timing adjustment resistor 17 in FIG. 2 is for adjusting such count start timing.

Next, determine whether the mode is release mode or program preview mode, and if it is release mode, the aperture end position 7
The 16th
(See figure) Turn on both the front curtain set magnet and the rear curtain set magnet of the shutter. Shutters having leading set magnets and trailing set magnets are well known. It takes about 30m5 from the start of the aperture count until the switch SW2 is turned on. When the motor 14 further rotates and reaches the mirror amplifier starting position 74, the switch SWI is turned on, thereby performing light measurement again and starting the mirror-up operation (see Figure 16C), and the mechanical charge of the shutter is released. is started. At this time, it is held by the front and rear curtains of the shutter and their respective set magnets.

The motor 14 rotates further to reach the mirror-up end position 75.
When the switch 2 is turned on, the motor 1 is turned on.
4 stops, the mirror-up operation is completed, and the mechanical charge release of the shutter is completed (see FIG. 16C).

The release causes the front curtain set magnet of the shutter to turn off and the front curtain begins to move.

At the same time, time is measured, and when the shutter opening/closing time calculated in advance based on the photometric value is reached, the trailing curtain cent magnet of the shutter is turned off and the trailing curtain starts moving. Thereafter, the combination solenoid 90 is energized in the forward direction to set it to the standby position, and the motor 14 is further rotated in the forward direction. The rotation of the motor 14 starts the return operation of the mirror, the rotation of the shank cam 38 turns the shank set lever 60 and starts mechanical charging of the shutter, and the rotation of the aperture cam 36 starts the aperture lever. 46 is rotated to start setting the aperture lever. During this time, film feeding is started.

When the motor 14 reaches the home position 71 in this manner, the motor 14 is stopped and film feeding is completed to prepare for the next release (see FIG. 16C).

The operation when the program preview mode is selected after the aperture lever stops moving will be described with reference to FIG. 17. In the program preview mode, when the switch SW2 is turned on after the aperture lever stops moving, the motor 14 is stopped.

Therefore, the shutter does not operate while the aperture is stopped down to a predetermined aperture value, and mirror amplification is not performed, so that it is possible to observe the depth of field, etc. at the predetermined aperture value. When the program preview is canceled, the combination solenoid 90 is energized in the forward direction to be in the standby position, and the motor 14 starts rotating in the reverse direction. As a result, the reverse centration of the aperture lever starts, and when the aperture count start position 72 is reached and the switch SWI is turned on, the reverse centration of the aperture lever ends, and the motor 14 stops rotating and returns to the home position 71. .

From the start of the motor's normal rotation shown in FIG. 17 to the end of the mirror up and the end of the release of the mechanical charge of the shutter, there are motor 14
It is desirable to rotate at a constant speed in order to control with high precision. The above embodiment incorporates a motor constant speed control device as described below.

In FIG. 2, the motor drive circuit 12 operates the motor 1 while turning on and off the power supply 13 according to commands from the MPUII.
When the motor 14 is on, the terminal voltage Vm of the motor 4 is equal to the power supply voltage vb, and when the motor 14 is off, Vm=Ve=KN. Here, Ve is a back electromotive voltage of the motor 14, K is a proportionality constant, and N is the number of rotations. The MPU II samples the terminal voltage Vm (=Ve) when the motor is off through the analog-to-digital converter 16, and controls the duty of the command signal to the motor drive circuit 12 so that the back electromotive force VeO value is constant.

4 and 5 show the operation of the constant speed control device described above. FIG. 4 shows the case where the power supply voltage vb is low, and FIG. 5 shows the case where the power supply voltage vb is high. As can be seen from this, when the power supply voltage is low, the duty of the command signal from the MPUII is high, and when the power supply voltage is low, the duty of the command signal from the MPUII is low, so that the rotational speed of the motor 14 is controlled to be constant. .

Further, in order to perform highly accurate control, it is desirable that the start-up of the rotation of the motor 14 is constant.

However, due to variations in the power supply voltage, the start-up of the motor's rotation also varies. Therefore, as shown in FIG. 3, the relationship between the ratio of the back electromotive voltage Ve of the motor to the target value Veo and the duty of the motor drive command signal from the MPUII is determined in advance by adjusting the duty as time passes after the motor is turned on. It is stored in the MPU II as a table, and the on time of the motor 14 is determined according to this table. In FIG. 3, arrows indicate the passage of time after the motor is turned on.

By doing so, when Ve/Veo is relatively large at a certain point, the motor-on duty is controlled to be low, and as a result, the rise of the motor rotation is controlled so as to follow a constant rise curve.

In order to detect the amount of rotation of the windmill 83 for determining the position of the aperture lever 46, a circuit as shown in FIG. 19 and an ankle mechanism as shown in FIG. 20 may be used. . In FIG. 20, the Gangi ratio 102 replaces the windmill 85 in FIG.
The ends of both arms of the ankle 103 are alternately in contact with the
02 rotates intermittently at fixed time intervals. Uncle 1
03 is the combination solenoid 90 in Fig. 7
This replaces the windmill 91 that the solenoid 90 has, and a back electromotive force is generated in the solenoid 90 each time the pallet pallet wheel 103 rotates back and forth while the solenoid 90 is not energized. Therefore, as shown in Fig. 2, the back electromotive force of the solenoid 90゛ is detected by the back electromotive pulse main output circuit 107, and this detection signal is sent to the MP
By inputting the input into the UII and counting, you can find out the rotating wheel with the Gangi rate of 102, and also the position of the aperture lever 46. When it is determined from the count that the aperture lever 46 has reached the predetermined position, the solenoid 90 is energized and the Gangi rate is adjusted. The rotation of 102 is stopped. The solenoid 9o in this case may be a monostable combination solenoid or a bistable combination solenoid. In the example shown in FIG. 19, the solenoid 90 is connected to the transistor 106 by the constant current source 105.
Driven through.

(Effects of the Invention) According to the present invention, the motor control unit that drives the motor while controlling the excitation of the motor on and off is configured to excite the motor so that the back electromotive voltage when the excitation of the motor is turned off is constant. Since it has a time control function, the rotational speed of the motor can be controlled to be constant, thereby preventing deviations in the timing of a series of operations of equipment driven by the motor and a decrease in position control accuracy.

[Brief explanation of the drawing]

Fig. 1 is a block diagram corresponding to complaints showing the basic configuration of the present invention, Fig. 2 is a block diagram showing an outline of a camera having the device of the present invention, and Fig. 3 is a speed control device when the motor in the same camera starts rotating. FIG. 4 is a timing chart showing an example of the operation of the embodiment of the constant speed control device according to the present invention, and FIG. 5 is a diagram showing an example of another operation of the above embodiment. Timing chart shown, No. 6
7 is a perspective view of the aperture position control mechanism of the camera; FIG. 8 is a front view of a portion of the aperture position control mechanism of the camera; and FIG. FIG. 10 is a front view of the aperture drive mechanism and shutter setting mechanism portion of the camera, FIG. 10 is a front view of the timing switch portion of the camera, and FIG. 11 is a vertical sectional view showing an example of the combination solenoid used in the camera. , Fig. 12 is a diagram of the operating principle of the same solenoid, Fig. 1
Figure 3 is a vertical sectional view showing another example of a combination solenoid, Figure 14 is a diagram of the operating principle of the same solenoid, and Figure 15 is a diagram showing the principle of operation of the same solenoid.
The figure is a circuit diagram showing an example of the drive circuit of the same solenoid.
6 is a timing chart showing the operation of the camera, FIG. 17 is a flowchart showing the operation of the camera,
Fig. 8 is a flowchart showing the υJ operation of the camera following Fig. 17, Fig. 19 is a circuit diagram showing another example of the aperture position control device, and Fig. 20 is a front view showing the mechanical part of the aperture position control device. It is. 1. Motor control section, 2. Back electromotive force detection section, 14.
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Claims (1)

[Claims] The motor control unit includes a motor control unit that drives the motor while controlling excitation of the motor on and off, and a back electromotive voltage detection unit that detects a back electromotive voltage of the motor when the excitation of the motor is turned off, and the motor control unit has: A constant speed control device, characterized in that the excitation on time of the motor is controlled so that the back electromotive force detected by the back electromotive force detection section is constant.