JPH01291225A - Stop controller - Google Patents

Abstract

PURPOSE:To prevent a stepping motor from stepping out making an actuation frequency lower when a stop is driven in an open state than when the stop is driven except from the open position. CONSTITUTION:The number of stop stages is converted into the number of driving steps of the stepping motor by a clock circuit 32 and a distributing circuit 33. A stepping motor driver circuit 34 determines which of coils 12 and 13 is powered on according to said number of steps to rotate the stepping motor by an optional quantity. In such a case, the actuation frequency is made lower when the stop is driven in the open state than when the stop is driven except from the open position (Start pulse intervals are made long). Consequently, the stepping motor is prevented from stepping out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an aperture control device of a type in which an aperture is driven by a step motor.

[Conventional technology]

Conventionally, an aperture control device of a type that drives an aperture using a step motor is known. In this type of aperture control device, by supplying the step motor with a number of pulses corresponding to the number of control stages of the aperture, the aperture can be set to any desired aperture opening, and its control is extremely simplified. On the other hand, the driving method for driving the step motor is disclosed in Patent No. 62-45.
As shown in No. 83, the driving frequency is increased from the start of driving to accelerate up to half the number of driving steps, and after the half, the driving frequency is lowered to smoothly decelerate.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, the same acceleration and deceleration is performed no matter where the driving start point is, so there are the following drawbacks.

■ Near the opening, the amount of movement of the aperture blades per unit number of stages is large, so the torque that drives the aperture becomes large, so in order to start the step motor without losing synchronization, it is necessary to significantly lower the starting frequency. . However, since the amount of movement of the diaphragm blades per unit number of stages becomes smaller in areas other than near the open position, the closer to the open position the start-up can be performed without lowering the starting frequency without losing synchronization. In order to drive these two different load states with the same driving frequency pattern, if you drive the engine at the starting frequency when opening when narrowing down, the driving time will be too slow compared to its actual ability when narrowing down, and conversely, when opening at the starting frequency when narrowing down. If you start driving from time to time, you will lose synchronization.

■ Near the opening, in addition to the case described in ■, since a mechanical switch is generally attached to detect the opening position, friction is added by this switch, which further increases the starting torque, which increases the starting frequency. I have to lower it.

[Means for solving problems]

According to the present invention, when detecting the open position, that is, when driving the aperture from the open state, the starting frequency is lowered than when driving from a position other than the open position, thereby preventing the step motor from stepping out. To provide an aperture control device which aims to shorten driving time by starting at a higher frequency than the starting frequency at the open position when driving from a position other than the open position.

〔Example〕

Hereinafter, embodiments will be described in detail according to the drawings.

FIG. 1 shows an exploded perspective view of an electromagnetically driven diaphragm device. Further, the assembled form is shown in FIG. 2. Reference number 1 is an annular base plate of a conductive member, and has an opening in the center through which photographing light passes. Main plate 1
A bearing 1a is formed in a part of the bearing 1a. A rotor shaft 2 is arranged parallel to the optical axis passing through the center of the lens barrel.A rotor magnet 3 is fixed to the shaft 2, and is supported by the bearing 1a, and a pinion gear 4 is connected to the tip of the rotor magnet 3. has been done.

The other rotor shaft is fitted into a bearing 5a provided in a fan-shaped bearing plate 5, and rotatably supports the rotor magnet 3. The rotor magnet 3 is made of, for example, a plastic magnet, and the outer periphery thereof is magnetized in a plurality of sections and alternately, and is oriented anisotropically. 6
and 7 are stators, and each stator has fork-shaped pole teeth 6a.
and 7a, and although both stators are shown separated from each other in the figure, in reality, the pole teeth 6a and 7a are intertwined so that they do not come into contact with each other. Also, the pole tooth 6a
and 7a are arranged along an arc so as to maintain equal distances from the surface of the rotor 3. Note that other stators 8 and 9, which are provided oppositely with the rotor 3 in between, also have a similar configuration.

Therefore, the magnetized cotton of the roller 3 has 6 to 9 pole teeth 6a to 9a.
is facing. 10 and 11 are iron cores arranged parallel to the optical axis, and a coil 12.1'3 is wound around the outer periphery. Furthermore, one end of the iron core 10 is caulked into the hole 5b of the bearing plate 5 through the hole 7b of the stator 7. Similarly, the other end of the iron core IO is caulked to the ground plate hole 1b via the hole 6b of the stator 6. Similarly, another iron core 11 has a hole 8b in the stator 8.9,
It is caulked into the hole 5c of the bearing plate 5 and the hole 1c of the base plate 1 through the hole 9b. Even if these iron cores are placed in the optical axis direction,
The diameter should be such that the iron core does not become magnetically saturated.

On the other hand, an arc-shaped portion of a flexible printed board 18 is adhered to the base plate 1, and a coil connection wire 12a is provided as a contact point.

13a is soldered.

Further, a switch mounting base 51 made of an insulating material is welded to the base plate 1 by a well-known method. 50 is a spring of a conductive member, and the pin portion 51 of the switch mounting base 51
a, one end is hung on the protrusion 51b of the switch mount 51, and the other end is hung on the switch pin 52 against the spring force.

Further, a lead wire 50a is soldered to one end I of the spring 50, and the lead wire 50a is connected to the flexible printed board 1.
It is soldered to the 8 contacts. The switch pin 52
is an eccentric pin whose caulking part is eccentric, and the base plate l
It is rotatably crimped, and a plurality of V grooves are formed on the outer periphery. The switch pin 52 is a conductive member (the surface is plated with gold), and is constantly connected to the ground plate 1 by crimping, and the ground plate 1 is soldered to the ground contact of the flexible printed board 18. There is. That is, the contact between the spring 50 and the switch pin 52 constitutes a switch. This switch serves as a switch for detecting whether or not the aperture is in an open state.

Next, the arrangement of the aperture device will be explained. A plurality of known aperture cams 15a are cut into the annular cam plate N5, and dowels 16a of each aperture blade 16 are fitted into the annular cam plate N5. − side aperture blade 1
The back dowels 16b of No. 6 are respectively fitted into a plurality of holes 17a formed in a rotating ring 17 that rotates around the optical axis. The rotating ring 17 fits into the outer shape 17b and the inner surface 15b of the spacing convex portions provided at four locations on the cam plate 15, and the cam plate 1
It is rotatable relative to 5. 17c is a rack cut concentrically around the periphery of the rotating ring 17, and meshes with the pinion gear 4. Alternatively, an arcuate slit may be made in the rotary ring 17 and a rack may be cut at the edge near the outer periphery of the slit.

17d is a projection that is inserted into the elongated hole 1e provided in the main plate 1 and collides with one end of the spring 50 so that when the aperture is opened, the spring 50 and the switch pin 52 are disconnected from each other and the switch is turned off. Department.

19 is a screw, which is a long hole 1 made in the convex part d of the cam plate 15.
Sandwich the rotating ring 17 via 5C (same 4 places),
It is tightened into the tap hole 1d of the main plate l.

The elongated hole 15c allows the rotational position of the cam plate 15 to be adjusted around the optical axis. This adjustment adjusts the aperture diameter to the standard value. The protrusion 17e of the rotary ring 17 opposes the protrusion 15d1 of the cam plate 15 to restrict rotation of the rotary ring 17. Further, rotation in the opposite direction is restricted by a rack end surface 17f provided on the periphery of the rotating ring 17.
and the convex end face 15e.

Next, the operation of the electromagnetically driven aperture device shown in FIGS. 1 and 2 will be explained with reference to FIGS. 3, 4, and 5.

(A) to (D) in FIG. 3 are diagrams showing the positional relationship between the rotor magnet 3 and the stators 6 to 9.

FIG. 3A shows a state in which the coils 12 and 13 are not energized. In this situation, rotor magnet 3
Since the poles of the rotor magnet 3 form a magnetic path through the stator, the poles of the rotor magnet 3 are stopped facing the stator 6.7. At that time, stator 8゜9 and rotor magnet 3
It is assumed that the two poles are not facing each other and are stopped at a position shifted by half a pitch (=1/2P).

Stator 6.7 and stator 8, so that they have this positional relationship,
They are arranged so as to be shifted by 1/2P from 9, and this can be expressed as θ=n P +1/2 P. P in FIG. 2A is the magnetization pitch of the rotor magnet 3, which is made to match the pitch of the stator 6.7 or the stators 8 and 9.

In the state of (b) in Figure 3, the coil 12 is in the opposite direction (↑ direction).
, is a diagram when the coil 13 is energized in the positive direction (↑ direction), and the respective states are designated as B and A. Similarly, coil 12
In the following explanation, the positive direction is assumed to be λ when the B1 coil 13 is energized in the reverse direction.

When the coil 12 is energized with a current of 100, N1 is generated in the stator 6, S is generated in the stator 7, and similarly, when the coil 13 is energized with A, a voltage N1 is generated in the stator 8, and S is generated in the starter 9. Therefore, each plate magnetized in advance on the outer periphery of the rotor magnet 3 and the pole generated on each stator pole tooth repel or attract each other, causing the rotor magnet 3 to rotate counterclockwise. At this time, the stators 6, 7 and 8, 9 are shifted by 1/2 pitch. 8. The poles of the rotor magnet 3, facing the magnet 9, try to maintain balance.

In other words, when the current is applied as shown in FIG. 3(B), the rotor magnet 3 moves 1/4 pitch counterclockwise relative to FIG. 3(A) and stably stops. Next, let's apply electricity as shown in Figure (C). In this case, the coil 12 is de-energized and only the coil 13 is energized A. At this time, the stator 8 has N
Since an S pole is generated in the stator 9, it attracts the pole of the rotor magnet 3, and is further 1/1
It will rotate 4 pitches counterclockwise. In Figure 3 (
d) The figure shows the case where the coil 12 is B1 and the coil 13 is energized by A, and since the principle is the same as in (b) to (c), the explanation of the operation will be omitted.

Based on the operating principle as explained above, FIG. 4 shows a timing chart of coil energization. In Fig. 4, the horizontal axis shows the number of pulses (or time), and the vertical axis shows whether the energization is ON or OFF.The timing chart shows the energization direction A,
The states of E, 8, and H are shown, and the bottom row shows the states corresponding to the states of 口, C, and 2 in FIG. A, B, A,
The state of combination B is shown in FIG. 4, and eight combinations from BA to 100 are possible.

One combination at this time is counted as one pulse. After the 9th pulse, the roke magnet 3 can be rotated to any angle by energizing the phase of the l-th pulse.

The state in which the diaphragm moves using a stepping motor as a driving source based on this principle will be explained with reference to FIG. First, when the rotor magnet 3 rotates, the pinion gear 4 rotates, and further, the rotating ring 17 rotates about the optical axis.

Here, the pinion gear 4 and the rack 17c constitute a speed reduction mechanism, and even if the torque of the rotor magnet 3 is relatively small, the rotating ring 17 can be sufficiently rotated. 16 moves relative to the fixed cam plate 15, so the tip of each aperture blade 16 moves in the radial direction.These actions are the same as those of a conventional mechanical aperture, so details will be omitted.Rotation of the rotating ring 17 Since the rotor magnet 3 rotates at equal intervals, the angle of rotation is constant. Therefore, by appropriately setting the shape of the cam groove 15a of the cam plate 15, the rotation angle of the rotary ring 17 and the number of stages of the aperture can be matched. I can do it.

Specifically, the relationship is set such that when the rotor magnet 3 advances by one step, the aperture diameter changes by 1/8 step. In other words, when the rotor magnet 3 is driven in eight steps, the aperture changes by one step.

FIG. 5 is a block diagram showing the process from when the camera's photometric system measures light until the aperture is stopped. The amount of light measured by the photometry circuit 30 of the camera is calculated in a well-known manner, taking into account factors such as film sensitivity, shutter speed, and aperture value, and the number of aperture stages is determined. This is done by the light amount setting circuit 31. The number of aperture stages is determined by the clock circuit 32 and the distribution circuit 3.
3 is converted into the number of drive steps of the step motor. By determining in which direction of the coil 12 or the coil 13 to be energized by the step motor driver circuit 34 according to the number of steps, the step motor can be rotated by an arbitrary amount. In other words, it becomes possible to match the specified aperture diameter. When returning the diaphragm blades, the rotor magnet 3 can be rotated clockwise by performing the operation explained in FIG. 3 in the opposite direction, returning it to the open state. 35 is a shutter drive circuit, and a light amount setting circuit 31
controlled based on the output of

On the other hand, the spring 50 and the switch pin 52 constitute a switch that is turned off when the aperture is open and turned on when the aperture is small. This switch is designed so that the camera performs open metering.
It is necessary to determine whether or not it is in an open state, and this switch is intended for this purpose. For example, when the blades move toward a smaller aperture due to an external impact, photometry is prohibited, and after the aperture blades are returned, photometry is performed again.

Figure 6 is a diagram showing the relationship between the stop position of the rotor magnet 3 of the l-2 phase drive step motor explained in Figure 3 and the aperture diameter, and is intended for a type where the aperture opening diameter is determined by the lathe diameter. .

■ indicates a stable position where the stepping motor can stop without energizing, that is, the one-phase energized position (rOJ) position, and ■ indicates a position where it can stop when two coils are energized simultaneously ("・").

■ is the position where the aperture is waiting in the open state, ■ is the lathe diameter that determines the open aperture, ■ is the position where the open state detection switch switches, ■ is the possible switching range of ■, and ■ is the mechanical At the stopper position, the step motor cannot rotate any further. In this embodiment, the gap between ■ and ■ is equivalent to 1/8 stop of the aperture. Considering the purpose of the open state detection switch, it is sufficient to determine whether the aperture is in the open aperture state or whether the aperture blades are protruding toward the small aperture side. However, these signals are generally generated by a mechanism that generates the signals mechanically, such as an electrical contact type or a method in which a brush is switched on the pattern, so it is difficult to adjust the signal to the desired position (the position of the lathe diameter ■). becomes difficult.

Therefore, the switching position of the above-mentioned switch has an adjustment range (2) to facilitate adjustment. This range (2) is designed to switch between the (2) phase position on the open side further than the lathe diameter and the (2) phase position on the smaller drawing side than the lathe diameter. In other words, the blade moves to the smaller aperture side than the lathe diameter, and before it stably stops in the non-energized state, the SW switches, and on the open side from the lathe diameter,
If the switching occurs before the phase reaches a stable position, it can be determined whether the phase is in the open state or not. This method facilitates adjustment to reduce the switch switching range to 1/4 stop or less, and enables a highly reliable electromagnetically driven diaphragm. In actual adjustment, the position (■) is created by energizing two phases, and the switching position is set at that electrically stable position.

Next, the operation of the open state detection switch will be explained with reference to FIG.

FIGS. 7(a) to (C) are state diagrams when the aperture is on the small aperture side. Note that Fig. 7(a) is a plan view of the main part, and Fig. 7(b) is a plan view of the main part.
) is a side view, and FIG. 7(C) is a side view of the main part of FIG. 7(b) viewed from direction A.

In this case, the protrusion 17d of the rotating ring 17 is connected to the spring 50.
Since the spring 50 and the switch pin 52 are not in contact with each other, the contact between the spring 50 and the switch pin 52 is maintained. That is, the open state detection switch is in the ON state and detects that the aperture is on the small aperture side. Then, when the aperture is returned to the open side, the protrusion 17d
rotates in the direction of the arrow and comes into contact with the spring 50.

The figure is FIG. 7(d) (plan view). Also this seventh
The position in Figure (d) corresponds to the position marked ■ in Figure 6. Note that the protrusion position 17' indicated by the two-dot chain line in Fig. 7(d)
d indicates the rotor magnet position when the step motor is energized, that is, the energization phase position. That is, this is the switching position of the open state detection switch.

Then, when the projection 17d is further rotated in the direction of the arrow against the spring force of the spring 50 from the state shown in FIG. 7(d), the contact between the spring 50 and the switch pin 52 is broken, and the open state detection switch is turned OFF. , detects that the aperture is wide open. The state diagram is shown in FIG. 7(e) (plan view).

Note that the rotation of the rotary ring 17 from the two-dot chain line position 17'd in FIG. 7(d) to the position shown in FIG. 7(e) is the phase when the rotor 3 is energized. The ON-OFF operation of the open state detection switch of this embodiment is as described above, and when the diaphragm is closed again, the reverse is true. As shown in enlarged views in FIGS. 7(b) and 7(c), a V-groove is formed on the outer periphery of the switch pin 52;
This is to increase the number of contact points (two) to reduce contact reliability (defects in contact due to debris, etc.).

Further, the switching timing of the switch is adjusted by rotating the switch pin 52, which is an eccentric pin, and changing the timing at which the protrusion 17d contacts the spring 50.

FIG. 8 shows the distribution circuit 33 and driver circuit 3 shown in FIG.
FIG. 4 is a circuit diagram showing an example of No. 4; In the figure, 101 is a microcomputer, which has output ports P, -P4 and input ports I. The output port P1 is a port for outputting a reset pulse, and outputs a reset pulse when the power switch is turned on or when the open switch 100 is turned off. Output port P2 is a motor rotation direction control port, P3 is a step pulse output port, and P4 is an energization control port.

102 is an inverter, and 103 and 104 are NOR gates. These inverters and NOR gates send out the step pulses from the NOR gate 104 when driving in the narrowing direction, and send out the step pulses from the NOR gate 1-103 when driving in the opening direction.

105 to 107 are D-type flip-flops constituting a binary counter. 112 to 114 are AND gates, and 108 to 110 are NOR gates, and when driving in the narrowing direction, these gates supply clock pulses to the binary counter in synchronization with the step pulse from the NOR gate 104, and count up the binary counter. let Also, when driving in the opening direction, the Noah gate 103
A switching gate is configured to cause the binary counter to down-count in synchronization with the step pulse from.

115 to 122 are AND gates that constitute a decoder, and each time the value changes from O to 7, a high level signal (hereinafter referred to as 1) is sent from the AND gate 115 toward the Nandt gate 122. ) is selectively output. 123 to 126 are OR gates, gate 123 outputs 1 when the count value of the binary counter is 5 to 7, gate 124 outputs 1 when the count value is 1 to 3, and gate 125 outputs 1 when the count value is 1 to 3. It outputs 1 when the count value is 3 to 5, and the gate 126 outputs 1 when the count value is 0.1.7. The count value and the output state of each gate 123-126 are as shown in FIG.

One gate of 128 to 131 is connected to the above output port P4, and the other input is connected to gates 123' to 1, respectively.
This is an AND gate connected to the output of 26. 132-1
35 is an inverter, 136 to 139 are drive transistors for coil 13, and 140 to 143 are coil 1.
This is the drive transistor for 2. The AND gates 128-131 are connected to the coil 12. 13, a current having the relationship shown in FIG. 10 is applied. FIG. 10 shows the coil 12 in FIG.
．． 13, and from these relationships, the motor rotates l steps each time the count value increases, and the diaphragm shifts to the 1/8 step narrowing side, and conversely, each time the count value decreases, the motor rotates l steps. The aperture is rotated step by step in the opposite direction to the above-mentioned up direction, and the aperture is shifted to the open side by 1/8 step.

The operation of the motor and diaphragm shown in FIG. 8 and FIG. 1 will be explained. Note that the microcomputer 101 is the first
The program is programmed to operate according to the flowchart shown in FIG.

Now, when the power is turned on by pressing the shutter button (not shown), the microcomputer 101 is activated and the first
The flow shown in FIG. 0 moves to step 1, and the steps thereafter are sequentially advanced.

[Step 5] Open switch 101 from output port 11
Read the state of , and if l (open state), step 2
If the result is 0 (narrowing down state), the process branches to step 11.

[Step 2] Aperture drive direction is 0PEN (opening direction)
If so, there is no need to drive the aperture, and the process ends. If it is CLO8E (narrowing down direction), the process branches to step 3.

[Step 3] Set the initial aperture drive step pulse interval T2 to Ts (initial value when not opening) 10T. (a gain that takes into account the torque increase due to the opening switch and the aperture cam groove 15a).

[Step 4] Substitute the above T2 into T2'.

[Step 5] Output O from output port P+ (reset binary counters 105 to 107).

[Step 6 Output 0 from output port P2 (direction toe).

[Step 7] Output 1 from output port P3.

[Step 8] Output l from output port P (end of binary counter reset).

[Step 9] Output 1 from output port P4 (diaphragm energization ON).

[Step 101 Wait for 18 hours to elapse.

In the above step, the binary counter is reset, the count value becomes O, the coil 13 is energized in the A direction, and then T. As time passes, the diaphragm stably stops at the O position shown in FIG.

[Step 11] Initial aperture drive step pulse interval T2
is set to the Ts.

[Step 12] Substitute the above T2 into T2'.

[Steps 13 to 15] If the aperture drive direction is in the opening direction, 1 is output from the output port P2, and if the aperture drive direction is in the narrowing direction, 0 is output from the output port P2 to set the drive direction.

[Step 16] Output 1 from output capo-1'P3.

[Step 17] Output 1 from output port P4 (diaphragm energization ON).

[Step 1B] Wait for the cicada at time To.

In steps 11 to 18 above, if the aperture is not in the open position at the start of driving, energization is started from the value stored in the binary counter, that is, from the energization phase at that position. Also, as in step 10, in order to stably stop at the current energized phase position, T is applied in step 18. It has a stable waiting time of time.

[Step 19] Output 0 from output port P3.

[Step 20] T, wait for time to pass.

[Step 21] Output 1 from output port P3.

As a result of the operations in steps 19 to 21, the gate 104 is selected because 0 is output from the output port P2 when driving in the narrowing direction, and the output of the output port P3 is sent out through the gate 104, and the binary counters 105 to 107 is counted as an amp.

Conversely, when driving in the open direction, 1 is output from the output port P2, so the gate 103 is selected, the binary counters 105 to 107 count down, and each aperture is driven by 1/8 step in either direction. .

[Step 22] Wait for T2' time to elapse before proceeding to the next energization phase.

[Step 23] If the driving direction is the opening direction, the process branches to step 24, and if the driving direction is the narrowing direction, the process branches to step 25.

[Step 241 Depending on the state of the open switch, if it is 1 (open), it will go to the drive end mode (step 34) and 0 (
If not (not open), the process branches to step 25.

[Step 25] Current number of driving steps (S T E
P ) and the total number of drive steps (MAXSTEP) are compared, and if they are equal, the process goes to step 32, the drive end mode, and if smaller, the process branches to step 26.

[Step 26] If the current number of drive steps (STEP) is equal to or larger than half of the total number of drive steps (MAXSTEP), the process branches to step 28; if it is smaller, the process branches to step 27.

[Step 27] If 5TEP<MAXSTEP/2, set T2-8T as the next aperture drive pulse interval.

[Step 28] 5TEP>= (MAXSTEP1
In case 2), T2+ΔT is set as the next aperture drive pulse interval.

Then, compare T2 calculated in step 27 or step 28 with the shortest pulse interval TMIN at which the step motor does not step out, and find that T2<TMIN.
If T 2 >:TMIN, the process branches to step 30.

[Step 30] If T 2 >=TMIN, the actual aperture drive pulse interval T2' is set to T2.

[Step 31] If T 2 < TMIN, then 1
゛2' is set to TMIN.

By repeating steps 19 to 31 above,
The diaphragm is driven by 1/8 step, and the drive pulse interval is shortened by ΔT until half of the drive amount is reached. In other words, the pulse is accelerated, and the drive pulse interval becomes longer by Δτ after half of the drive amount. In other words, the speed is reduced.

From step 32 onwards, the aperture drive is performed in the above-described procedure, and the process is completed after driving the entire drive amount.

[Step 32] Read the open switch from the input port 11, and if it is 0 (non-open state), go to step 32 and set 1.
(open state), the process branches to step 34.

[Step 33] In order to stably stop the aperture, the energized state of the coil during the final drive is maintained for T3 time, and the drive is ended.

[Step 34] Output O from the main port P1 and reset the binary counters 105 to 107.

When the binary counter is reset, the count value of the counter becomes 0, and the coil 13 is energized in the A direction. Since this energization phase is the energization phase of the coil at the position O in FIG. 6, the rotor moves to FIG. 6C.

[Step 35] The aperture rotor is maintained at the position O for 13 hours in order to stably stop it.

[Step 36] O is output from the output port P4, and the energization of the motor is stopped to stop the drive.

FIG. 12 is a diagram showing changes in the aperture driving pulse interval due to the operation described above, in which 12a shows the pulse interval due to driving from the time of opening, and 12b shows the pulse interval due to driving from the time of non-opening.

〔Effect of the invention〕

As explained above, the present invention prevents the step motor from stepping out by lowering the starting frequency (lengthening the starting pulse interval) when driving the aperture from an open position than when driving from a position other than the open position. To provide an diaphragm control device which has the effect of shortening drive time by increasing the starting frequency (shortening the starting pulse interval) at the open position when driving from a position other than the open position.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of an electromagnetically driven aperture unit according to an embodiment of the present invention. FIG. 2 is an assembly diagram of the electromagnetically driven aperture unit shown in FIG. 1. Figure 3 is a diagram of the principle of a step motor. Figure 4 is a diagram of the energization timing of the step motor. FIG. 5 is a block diagram of the step motor drive circuit. FIG. 6 is a diagram showing the relationship between the motor stop positions of the step motor according to the embodiment of the present invention. FIGS. 7(a) to 7(e) are operational diagrams of the aperture open state detection means according to the embodiment of the present invention. FIG. 8 is a circuit diagram showing an embodiment of the distribution circuit and driver circuit shown in FIG. FIG. 9 shows the count value of the counter shown in FIG. 7 and the gate 12.
An explanatory diagram showing output states of Nos. 3 to 126. FIG. 1O is an explanatory diagram showing the relationship between the count value of the counter shown in FIG. 8 and the energization state of the coils 12 and 13. FIG. 11 is an explanatory diagram showing a flow for explaining the operation of the control circuit shown in FIG. 12th
The figure shows the energization time of each energization phase of the step motor driven by the program.

Claims (1)

[Claims] (1) an aperture mechanism that supplies pulses to a step motor, drives the motor in steps using the supplied pulses, and uses the motor as a drive source to change the aperture aperture from an open state to the narrowed-down side or from a narrowed-down position to an open state;
In an aperture control device equipped with means for detecting an open state, when the pulse forming circuit that supplies pulses to the motor is activated, the aperture drive starting point is lower when the aperture is in the open state than when driving from a non-open state. An aperture control device characterized by being provided with a starting circuit that starts at a starting frequency.