JPH03107832A - Electromagnetically driven exposure controller - Google Patents

Abstract

PURPOSE:To obtain the high accuracy of an aperture diameter by directly driving a rotating ring which opens/closes the light shielding vanes without the aid of gears. CONSTITUTION:This device has a permanent magnet 4 which is made into an arc shape, is magnetized to plural poles in the thickness direction and is fixed to the rotating ring 3 and 1st to 4th stators 5 to 8. The permanent magnet 4 is magnetized at a prescribed pitch to plural poles in the thickness direction and the 1st to 4th stators have magnetic pole groups 5a to 5e, 6a to 6e, 7a to 7e, 8a to 8e. Cams equal to the number of the plural light shielding vanes are formed on a cam member 1 which freely rotatably supports the rotating ring 3. The light shielding vanes fit to the cams and these light shielding vanes fit into the holes of the rotating ring 3. The permanent magnet 4 moves by 45 deg. electrical angle each when 1st and 2nd coils 9, 10 are subjected to 1-2 phase energization. Thus, the rotating ring 3 rotates together with the permanent magnet 4 and the roots of the light shielding vanes are opened/closed. A prescribed exposure is thus obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exposure amount adjustment device for a camera, and in particular to an electromagnetic drive type in which an electromagnetic actuator for driving a light-shielding blade and an exposure amount adjustment device body are integrated. The present invention relates to an exposure amount adjustment device.

[Prior art] Conventionally, a non-interchangeable lens type 35 called a compact camera
mm camera has an electromagnetic actuator (i.e. motor)
It was equipped with an electromagnetic exposure adjustment device (or a directly electric shutter and aperture device) that was directly driven by the
Recently, replacement lenses for single-lens reflex cameras have come to be equipped with electromagnetic aperture drive devices that directly drive the aperture blades using an electromagnetic actuator (ie, a motor).

The advantage of the electromagnetically driven exposure amount adjustment device in which the motor directly drives the shading blades is that the dynamic force transmission path for driving the shading blades is extremely short, resulting in good control responsiveness.
It is suitable for electronic control.

Conventionally, devices having the following structure have been proposed as electromagnetically driven exposure amount adjusting devices as described above.

(i) It has a rotor made of a cylindrical permanent magnet, and the rotor is composed of S poles and N poles parallel to the axis, which are alternately magnetized along the circumferential direction, and the rotation of the rotor is A device configured to rotate a known light-shielding blade support ring by decelerating it using a gear mechanism (see Japanese Patent Laid-Open No. 82-240942).

(if) It has a ring-shaped rotor made of a permanent magnet in which N poles and Si are alternately magnetized on the outer periphery, and the rotor is fixed to a known light-shielding blade supporting ring, and the ring and the rotor (Japanese Unexamined Patent Publication No. 57-165825)
(see publication).

(li+) The light-shielding blade supporting ring is constructed of a permanent magnet, and the ring itself is constructed as a rotor of a motor (see Japanese Utility Model Application No. 62-64176).

[Problem N to be solved by the invention] In the electromagnetically driven exposure amount adjusting device described above, in order to simplify the configuration of the control system, a stepping motor is adopted as the motor for driving the light shielding blades. 8 Motion control and position control are performed by so-called oven loop control. Therefore, the momentary position and speed of the shading blade are not fed back to the motor, so in order to perform 8-force control and position control of the shading blade with high precision, it is necessary to adjust the electrical phase of the stepping motor. It is necessary that the aperture diameter corresponds as precisely as possible.

On the other hand, in the case of a lens shutter mechanism that functions as both an aperture and a shutter, it is necessary to drive the light shielding blades with rapid acceleration and deceleration, and at the same time, it is necessary to control the stop position with high precision, so the amount of drive of the stepping motor is required. A more accurate correspondence is required between the driving amount of the light shielding blade and the driving amount of the light shielding blade.

However, the above-mentioned known exposure amount adjustment device has the following problems, so it is difficult to adjust the exposure amount with high precision.

(a) The exposure amount adjusting device disclosed in Japanese Patent Application Laid-Open No. 62-240942 has a structure in which the rotation of the rotor is transmitted to the light-shielding blade supporting ring through a gear, so that the backlash of the gear is Therefore, it was inevitable that some error would occur between the phase of the stepping motor and the accuracy of the aperture diameter.

In addition, since this device requires a housing member for pivotally supporting the rotor and for attaching the stator, there are other drawbacks such as a large number of parts and an increase in the size of the device.

(b) The exposure amount adjusting device disclosed in JP-A-57-165825 has a large diameter rotor made of ring-shaped permanent 6n stones, so the moment of inertia of the rotor is large. Since a large amount of electric power is required to perform this operation, there is a drawback that the battery consumption rate is high. Further, since the moment of inertia of the rotor is large, the accuracy of the stop position is low, and therefore it is difficult to adjust the exposure amount with high precision. Moreover, since the components of the stepping motor, including the rotor, are large in size, the apparatus also has the drawback of being large in size and expensive to manufacture.

(c) In the exposure amount adjusting device disclosed in Japanese Utility Model Application Publication No. 62-64176, the first magnetic pole portion (pole piece) of the stator corresponding to the first open end of the armature coil and the armature coil Since the second magnetic pole parts (pole pieces) of the stator corresponding to the second open end of the stator are arranged close to each other, the inductance of the coil is large, and therefore the current for generating torque in the rotor is large. Difficult to flow into. As a result, the rotor cannot be rapidly accelerated or decelerated, and therefore highly accurate exposure adjustment cannot be performed. Also,
A large amount of power is required to complete the operation within a predetermined time, resulting in large power consumption.

Therefore, an object of the present invention is to provide an improved electromagnetic drive that solves the problems inherent in the conventional exposure adjustment device described above, enables high-precision exposure adjustment, and can be manufactured at relatively low cost. An object of the present invention is to provide an exposure adjustment device.

[Means for Solving the Problems] The electromagnetic drive exposure amount adjusting device of the present invention has (1) an arc shape and is magnetized into multiple poles in the thickness direction;
a permanent magnet fixed to a rotating ring; a fixed first stator; (3) a first end magnetically coupled to a second end of the first stator, the second end having a second end of the permanent magnet; a second magnetic pole fixed to the cam member, which faces the magnetized surface of No. 2 with a predetermined gap therebetween, and has a second magnetic pole at a position opposite to the first magnetic pole with the permanent magnet in between; (4) a first stator of a magnetic path consisting of the first and second stators;
(5) a first armature coil wound between the magnetic pole part of the permanent magnet and the second magnetic pole part; a third stator having a third magnetic pole part electrically out of phase with the first magnetic pole part by 90 degrees at the first end and fixed to the cam member; (6) a third stator of the third stator; a first end that magnetically couples with the end of the second permanent magnet, and a second end that faces the second magnetized surface of the permanent magnet with a predetermined gap therebetween;
and a fourth stator fixed to a cam member having a fourth magnetic pole portion at a position opposite to the third magnetic pole portion and the permanent magnet, (7) from the third and fourth stators. The third magnetic path consisting of
and a second armature coil wound between the magnetic pole part and the fourth magnetic pole part. In the device of the present invention, high aperture diameter accuracy can be obtained with respect to the step angle of the rotor, and since the moment of inertia and coil inductance of the device of the present invention are smaller than conventional devices, it can be driven with less electric power. The device has fewer parts than conventional devices, so it can be manufactured at a lower cost.

[Embodiment] FIG. 1(A) shows a perspective view of a first embodiment of the device of the present invention, and FIG. 1(B) shows an exploded perspective view of the first embodiment of the device of the present invention.

In FIG. 1(A) and FIG. 1(B), 1 is a cam member, 2 is a light shielding blade, 3 is a rotating ring, 4 is a permanent magnet, 5 is a first stator, 6 is a second stator, 7 is a third stator, and in this embodiment, the first stator 5 and the third stator 7 are integrally formed. 8 is a fourth stator, 9 is a first armature coil, and 10 is a second armature coil.

FIG. 2 is an explanatory diagram of the arrangement of magnetic poles of the electromagnetic drive exposure amount adjusting device according to the present invention, FIG. 3 is a sectional view of the same main part, and FIG. 4 is an explanatory diagram of the operation. In FIGS. 2 to 4, parts corresponding to those in FIG. 1 are given the same reference numerals.

In FIG. 1(B), a cam member 1 made of plastic has cams la and l equal in number to a plurality of light-shielding blades.
b, lc, ld, 1. e is formed. for example,
The light-shielding blade 2 made of plastic molding is shown in Figure 1 (B
), only one sheet is shown and the others are omitted. A first dowel 2a of a light shielding blade 2 is fitted into a cam 1a provided on the cam member 1. The second dowel 2b of the light-shielding blade 2 is a rotating ring 3 made of plastic, for example.
It fits into the hole 3a provided in the.

Outer periphery 3Jl-34 of rotating ring 3. is fitted into the inner peripheral portion 1q of the cam member 1 and is rotatably supported. In addition, the projections if, Ig, 1h, it, l provided on the cam member 1
j is a state in which the light shielding blade and the rotating ring 3 are installed,
When the rotating ring 3 is in a predetermined angular position range, the pawl has a bayonet structure that restricts the position of the rotating ring 3 in the optical axis direction.

The substantially arc-shaped permanent magnet 4 is made of, for example, a plastic magnet, and is magnetized into a plurality of poles at a predetermined pitch in the thickness direction. The permanent magnet 4 has first and second holes 4a, 4
b, and each hole is fitted with the first dowel 3g on the first protrusion 3f and the second dowel 31 on the second protrusion 3h provided on the rotary ring 3, and the holes are fitted with the first dowel 3g on the first protrusion 3f and the second dowel 31 on the second protrusion 3h. Permanent magnet 4 is fixed to rotating ring 3 by known means.

For example, the first one is made by pressing a silicon steel plate.
The stator members 11 have an angle approximately equal to the magnetization opening/closing angle of the permanent magnets 4, as shown in the magnetic poles and the phase relationship in FIG. The first magnetic pole groups 5a to 5e (5c and 5d are not shown) and the third magnetic pole groups 78 to 7e (5c and 5d are not shown) are disposed with a phase difference of 90 degrees in electrical angle. 7b (not shown). Further, the first stator member 11 has holes 11a, llb, and llc for positioning and fixing, and each of the first stator member 11 has holes 11a, llb, and llc for positioning and fixing, and the first stator member 11 has holes 11a, llb, and llc for positioning and fixing, respectively. Second. Third protrusion lk
, 1m, io. 2nd ° 3rd dowel 1
The first stator member 11 is fitted with the cam members fl, 1n, and ip, and is positioned and fixed to the cam member 1 by known means such as thermal caulking.

When the first stator member 11 is positioned and fixed to the cam member 11, the first and third magnetic pole groups 5a to 5
e, 7a to 7e face the first magnetized surface 4c of the permanent magnet 4 with a predetermined gap in between.

First magnetic pole group 58 provided on first stator member 11
Extended portions 5g and 5f are provided at the inner diameter side end portions of ~5e. Furthermore, extensions 7g and 7f are also provided at the inner diameter side ends of the third magnetic pole groups 7a to 7e provided in the first stator 11. The second stator member 6 is made, for example, by pressing a silicon steel plate, and has second magnetic pole groups 6a to 6e whose phase relationship is shown in FIG. 2 with respect to the magnetic poles. Extended portions 6g and 6f are provided on the outer peripheral side of the second stator member 6 having the second magnetic pole groups 6a to 6e.

Furthermore, the second magnetic pole group 68 to 6e of the second stator member 6
First and second protrusions 6h and 6i are provided on the same surface as the cam member 1, and are inserted into the first and second stator fixing grooves lr and 1s (1r is not shown) provided in the cam member 1. is,
The position is fixed. The third stator member 8 is made by pressing a silicon steel plate, for example, and has fourth magnetic pole groups 8a to 8e whose magnetic pole widths and phase relationships are shown in FIG.

Further, on the outer peripheral side of the third stator member 8, an extension portion 8g,
8f is provided. Further, first and second protrusions 8h and 8i are provided on the same surface as the fourth magnetic pole group 88 to 8e of the third stator member 8, and third and fourth protrusions provided on the cam member 1 are inserted into the stator fixing grooves 1t and 1u (lu is not shown), and are positioned and fixed by well-known means such as adhesive.

In the assembled state of each component as shown in FIG. 1(A), the first extension portion 5f of the first stator member 11 is
As shown in the figure, it contacts the extension portion 6f of the second stator member 6 and is magnetically coupled to it.

Further, the first armature coil 9 is an air-core coil, and is inserted through the first extension portion 5f of the first stator member 11 and the extension portion 6f of the second stator member 6. Further, as shown in a cross-sectional view in FIG. 3, the second elongated portion 7f of the first stator member 11 contacts and magnetically couples with the elongated portion 8f of the third stator member 8. Furthermore, the second armature coil 10
is an air core coil, and the second stator member 11 is an air core coil.
and the extension portion 8f of the third stator member 8. First and second terminals 9a, 9b, ! of the first and second armature coils, respectively! Oa and 10b are connected to a known stepping motor drive circuit via a flexible printed wiring board (not shown).

In the assembled state of each component as shown in FIG. Since the rotation angle is regulated, the rotation ring 3 is connected to the cam member 1.
f.

It never deviates from Ig, lh, it, lj.

Next, referring to FIG. 4, the operation of the electromagnetically driven exposure adjusting device according to the present invention will be explained.

In FIG. 4, the magnetic pole parts of each magnetic pole group are 5a, 5a,
5b, 6a, 6b, 7a, 7b.

Only 8a and 8b are shown, and the others are omitted.

When the first coil 9 is energized to a predetermined value, the first magnetic pole groups 5a, 5b, . . . have S poles excited, and the second magnetic pole groups 6a, 6b, . . . have N poles. Excited. Also, the third
．． Since the magnetic paths of the fourth magnetic pole group are also connected, these third... Fourth magnetic pole group and permanent magnet 4
The forces acting on the
The coil 9 is energized to form the first magnetic pole group 5a.

5b... is excited to the S pole, the permanent magnet 4 becomes as shown in Fig. 4 (
Stop at the position shown in a).

Next, the fourth magnetic pole group 8a is attached to the second coil 10.

When magnets 8b... are energized to the S pole, the permanent magnet 4 moves by 45 degrees in electrical angle, that is, to the position shown in FIG. 4(b).

Next, when the first coil 9 is de-energized, the permanent magnet 4 moves further by 45 degrees in electrical angle, that is, to the position shown in FIG. 4(C). In this way, by performing the well-known 1-2 phase energization to the first and second coils, the permanent magnet 4 is
Move by °. Therefore, by rotating the rotating ring 3 together with the permanent magnet 4 and opening and closing the light-shielding vane plate 2, a predetermined amount of exposure can be obtained.

In addition, in the first embodiment of the present invention described above, the first stator member 11 is provided with the first magnetic pole group and the second magnetic pole group, but each magnetic pole group is separated to form the first magnetic pole group. It goes without saying that the same effects as the first embodiment of the present invention can be obtained even if the second stator member has a group of magnetic poles and the fourth stator member has a second group of magnetic poles.

[Effects of the Invention] As described above, according to the electromagnetic drive exposure amount adjusting device according to the present invention, 1. Since the rotating ring that opens and closes the light-shielding blade plate is directly driven without using a gear, It becomes possible to obtain high aperture diameter accuracy.

2. Since the stepping motor can be constructed with a simple shape, small size, and a small number of parts, it is possible to provide an inexpensive electromagnetic drive exposure adjustment device.

3. Since the magnetic poles of each stator can be configured without being close to each other, the inductance of the coil can be kept low, and therefore high-speed operation can be achieved with less electric power.

Effects such as this can be obtained.

[Brief explanation of drawings]

FIG. 1(A) is a perspective view showing one embodiment of the exposure amount adjusting device of the present invention, FIG. 1(B) is an exploded perspective view of the device shown in FIG. 1(A), and FIG. 3 is a longitudinal sectional view of the device shown in FIG. 1(A), and FIGS. 4(a) to 4(c) are diagrams showing the arrangement of magnetic poles of the device shown in FIG. FIG. 3 is a diagram showing the relative positional relationship of magnetic poles during operation. 1... Cam member 2... Shading blade 3... Rotating ring 4... Permanent magnet 11... First stator member 6... Second stator member 8... Third Stator member 9...First coil 10...Second coil and 4 others Figure (8) Figure (A)

Claims (1)

[Claims] 1. A shading blade, a cam member having a cam that fits with a first dowel provided on the shading blade to restrict movement of the shading blade, and a cam member that fits with a second dowel provided on the shading blade. a rotating ring having mating holes for opening and closing the light shielding blade; a permanent magnet having a substantially arc shape and magnetized with multiple poles in the thickness direction and fixed to the rotating ring; and a first permanent magnet of the permanent magnet. The first magnetic pole part facing the magnetized surface of the
and a first cam member fixed to the cam member.
a stator, a first end that is magnetically coupled to a second end of the first stator, and a second end that has a second magnetized surface of the permanent magnet and a predetermined gap. a second stator fixed to the cam member and having a second magnetic pole portion at a position opposite to the first magnetic pole portion with the permanent magnet in between; A first armature coil wound between a first magnetic pole part and a second magnetic pole part of a magnetic path consisting of a stator, and a first magnetized surface of the permanent magnet through a predetermined gap. a third stator having a third magnetic pole part facing the first magnetic pole part electrically out of phase by 90 degrees at the first end and fixed to the cam member; a first end that magnetically couples with a second end of the permanent magnet, and a second end that faces the second magnetized surface of the permanent magnet with a predetermined gap therebetween; a fourth stator fixed to the cam member, which has a fourth magnetic pole portion at a position opposite to the third magnetic pole portion with the permanent magnet in between; An electromagnetic drive exposure amount adjusting device comprising: a magnetic pole portion; and a second armature coil wound between the fourth magnetic pole portion.