JPH03207254A - Exposure value adjusting device - Google Patents

Abstract

PURPOSE:To stably obtain high diaphragm accuracy by providing the first and second magnetic pole parts, having a specific opening angle, in point end parts of the first and second extension parts, being separated at a specific electric angle, while arranging the first and second stators being separated at a specific electric angle. CONSTITUTION:Magnetic pole parts (6a, 6c), (7a, 7c) are provided respectively in point end parts of each extension part (6b, 6d), (7b, 7d) of stators 6, 7, and the magnetic pole parts (6a, 6c), (7a, 7c) are provided with an almost 90 deg. opening angle respectively by an electric angle while separated 180 deg. from each other by an electric angle. While the magnetic pole part 6a of the stator 6 and the second magnetic pole part 7c of the stator 7 are 630 deg. separated from each other by an electric angle, that is, equivalent to a 90 deg. phase difference between the stators 6, 7, and a diaphragm device can be driven to a predetermined diaphragm value or returned to an opening position by a command from a camera.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exposure amount adjustment device that adjusts the amount of exposure using a stepping motor used in still cameras, video cameras, etc. as a driving power source, and in particular, Regarding the stepping motor that is the source.

[Conventional technology]

2. Description of the Related Art In recent years, the mainstream of exposure amount adjusting devices that serve as both a shutter device and an aperture device in non-interchangeable lens cameras, generally referred to as compact cameras, is one that uses a stepping motor as a driving power source. On the other hand, the aperture device in the interchangeable lens of a -eye reflex camera is also driven using a stepping motor as a power source.

As an electromagnetic drive exposure adjustment device using such a stepping motor as a driving power source, there is a patent application published in Utility Model Application No. 61-17913.
9. Jitsugan Sho 61-194283, Jitsugan Sho 61-1972
12. As disclosed in Japanese Patent Application No. 61-309396, etc., a bow-shaped substrate, a rotor with four poles magnetized on the outer periphery, a pair of approximately U-shaped stators, and each 2. Description of the Related Art There is known an electromagnetic drive exposure amount adjusting device whose drive power source is a stepping motor consisting of a pair of coils for exciting a stator.

In addition, as shown in Jitsuma 62-240942, etc., each coil is wound around an iron core that is parallel to the rotor axis, and the other is a coil that is installed on a surface perpendicular to the rotor axis and is connected to the outer peripheral surface of the rotor. There is also known an exposure I adjustment device that uses a stepping motor as a driving power source, and includes a pair of stators each made up of two magnetic pole members, each having a plurality of opposing magnetic pole parts.

[Problems to be Solved by the Invention] By the way, in the case of an exposure adjustment device using the above-mentioned stepping motor as a driving power source, for example for an eye reflex camera, the stepping motor is energized from a predetermined phase. The aperture diameter is determined by how many steps the rotor rotates after starting. Therefore, in order to obtain a highly accurate aperture diameter, it is desirable that the angle at which the rotor rotates per one step is small. On the other hand, in order to avoid draining the battery that serves as the power source, it is desirable to turn off the power to the motor when performing relatively long exposures.To do this, the cogging torque must be used to stably stop the rotor per rotation. It is desirable that there be many stopping positions. However, in the conventional example, when the well-known one- and two-phase energization is performed, the rotor 1
Although the number of pulses required for rotation is 16 pulses, there are only four stable stopping positions due to cogging torque, which is equal to the number of magnetized poles. Therefore, even when performing relatively long exposures, a large aperture diameter is required. In order to obtain accuracy, the coil must be continuously energized, which poses the problem of large consumption of the battery that serves as the power source.

In addition, in the electromagnetic drive exposure amount adjusting device as disclosed in Jitsuma 62-240942, since the stator is arranged three-dimensionally, it is difficult to accurately arrange the phase of each magnetic pole, and the cost is high. There has been a problem in that it is difficult to stably obtain aperture diameter accuracy.

[Means to solve the problem]

In order to solve the above-mentioned drawbacks of the prior art, the present invention provides a stepping motor that serves as a driving power source for an electromagnetic exposure amount adjustment device, which is magnetized with 2n poles (n = 2.3°...). The rotor has a groove in the center thereof, and the first and second magnetic pole portions have an opening angle of approximately 90 degrees in electrical angle.
and the first and second stators, which are provided at the tip of the second extension part and spaced apart by approximately 180 degrees in electrical angle, and have an excitation coil wound around the first extension part. 90+180
xm)' (m=o, 1.-) spaced apart from each other.

〔Example〕

The present invention will be described below with reference to FIGS. 1 and 2, with reference to FIGS. 1 and 2, with reference to FIGS.

FIG. 1 is an exploded perspective view of an electromagnetically driven exposure amount adjusting device according to the present invention, and FIG. 2 is a front view of a portion of a stepping motor.

1 is a ring-shaped cam member, 2 is a light shielding blade, 3 is a rotating ring, 4 is a rotor, 5 is a fixed ring, 6 is a first stator, 7 is a second stator, 8 is a first armature coil, 9 is a second armature coil, 10 is a bearing member, and 11 is a flexible printed circuit board.

In FIG. 1, a cam member 1 made of plastic, for example, is provided with groove-shaped cams la, lb, lc, ld, and 1e equal to the number of light shielding blades 2, and convex portions 15. Ig.

1h and 11 are provided, and convex portions 15. Ig, lh and 1
The inner peripheral portion of the optical axis 100 of the rotary ring 3 fits into the outer diameter portion 3a of the rotary ring 3, and rotatably supports the rotary ring 3.

In addition, the convex portion 15. Ig, lh and 11 are each provided with a hole, and screws 13a, 13b, 1 are inserted through the hole.
The cam member 1 is fixed to the fixing ring 5 by fixing the screw holes 3c and 13d (13b to 13d are not shown) to the screw holes 5a, 5b, 5c, and 5d provided in the fixing ring 5.

For example, the number of light shielding blades 2 made of plastic is equal to the number of cams 1a to 1e provided on the cam member 1, but only one is shown in FIG. 1 and the others are omitted.

The first dowel 2a provided on the light shielding blade 2 is connected to the cam member 1.
The second dowel 2b fits into a first hole 3b provided in the rotating ring 3.

The respective first and second light shielding blades of the second to fifth light shielding blades (not shown)
The dowel also connects the cam and rotating ring 3 provided on the cam member 1.
It fits into the hole provided in the.

Convex portion 15 of cam member 1. Ig, lh, and 11 each have a height that is a predetermined amount larger than the sum of the thickness of the rotating ring 3 and the thickness of the light shielding blade 2, and the cam member 1 and the fixed ring 5 are connected to the rotating ring 3. When the light shielding blade 2 is installed and fixed by the screws 13a to 13d, the rotation ring 3 has a predetermined backlash and its position in the optical axis direction is restricted. A gear 3f is provided on a part of the outer circumference of the rotating ring 3.

The cam member 1 is provided with a bearing portion 1j, which pivotally supports the first shaft portion 4d of the rotor 4.

For example, the fixing ring 5 integrally made of plastic is provided with a first pedestal part 5e, a second pedestal part 5o, and a third pedestal part 5h. First pedestal part 5e
, a first stator 6 for positioning the first stator 6;
A positioning pin 5f and a first groove 5g having a step are provided. Similarly, the second pedestal portion 50 is provided with a second positioning bin 5p for positioning the second stator 7 and a second groove 5q having a step.

The third pedestal portion 5h is provided with a hole 5j that is larger than the outer diameter of the rotor 4 by a predetermined amount, and the first stator 6
a first extension section 51 for positioning the stator 7; and a second extension section 5m for positioning the second stator 7.
is provided.

Further, the third pedestal portion 5h has a third, fourth, and so on having a step. Fifth grooves 5h, 5j2, and 5n (the fifth groove 5n is not shown) are provided.

The first stator 6 is made by laminating silicon steel plates, for example, and has a substantially U-shape as shown in FIG. 1st
First and second magnetic pole parts 6a and 6c (first and second magnetic pole parts 6a and 6c), which face the outer peripheral part of the rotor 4 through a predetermined gap, are respectively disposed at the tips of the first and second extension parts 6b and 6d of the stator 6. (see Figure 2). The first of the first stator 6
The second magnetic pole portions 6a and 6c each have an opening angle of approximately 90 degrees in electrical angle, and have an opening angle of approximately 180 degrees in electrical angle with respect to each other.
° Spaced apart.

A first armature coil 8 is installed in the first extension portion 6b of the first stator 6.

The first armature coil 8 is constructed by winding a copper wire 8b around a bobbin 8a made of plastic, and soldering both ends (start and end of winding) of the copper wire 8b to terminals gc and 8d press-fitted into the bobbin 8a. The attachment is electrically connected by means such as the following.

Furthermore, the first stator 6 is provided with a positioning hole 6e.

The second stator 7 is made by laminating silicon steel plates, for example, and has a substantially U-shape as shown in FIG. Second
First and second magnetic pole portions 7a and 7c are provided at the tips of the first and second extension portions 7b and 7d of the stator 7, respectively, to face the outer peripheral portion of the rotor 4 with a predetermined gap therebetween. It is being

The first and second magnetic pole parts 7a of the second stator 7.

7c each have an opening angle of approximately 90 degrees in electrical angle and are spaced apart from each other by 1800 degrees in electrical angle.

An armature coil 9 is installed in the first extension portion 7b of the second stator 7.

The second armature coil 9 has a copper wire 9b wound around a bobbin 9a made of plastic, and terminals 9c and 9d press-fitted into the bobbin at both ends (start and end of winding) of the copper wire 9b.
are electrically connected by means such as soldering. Further, the second stator 7 is provided with a positioning hole 7e.

When the first stator 6 is assembled to the fixed ring 5, the first stator 6 is positioned in the optical axis direction by contacting the first and third convex portions 5e and 5h of the fixed ring 5, and the first stator 6 is positioned in the optical axis direction. The hole 6e of the first stator 6 and the first positioning pin 5f provided on the fixing ring 5 fit together, and as shown in FIG. By fitting the first extending portion 51 of the fixing ring 5 into the gap between the extending portions 6c, positioning in the direction perpendicular to the optical axis is achieved.

Similar to the first stator 6, when the second stator 7 is assembled to the fixed ring 5, the second stator 7 is positioned in the optical axis direction by contacting the second and third convex portions 50 and 5h of the fixed ring 5. is carried out, and the hole 7e of the second stator 7 and the second positioning pin 5p provided in the fixing ring 5 are fitted, and as shown in FIG. The fixing ring 5 is placed in the gap between the second extending portion 7b and the second extending portion
By fitting the second extension portion 5m, positioning is performed in a direction perpendicular to the optical axis.

The rotor 4 is made of plastic magnets, and the first rotor 4 is made of plastic magnets.
The second rotating shafts 4d and 4e, the gear 40, and the magnetic pole portion 4a are integrally molded. The magnetic pole portion 4a of the rotor 4 has polar anisotropy so that 8 even magnetic poles are formed on the outer periphery, and is also magnetized so that 8 even magnetic poles are formed on the outer periphery. has been done. Furthermore, a groove 4b is provided at the center of each of the N pole and S pole of the magnetic poles 4a of the rotor 4. A first rotation shaft 4d of the rotor 4 is rotatably supported by a first bearing 1j provided on the cam member 1.

On the other hand, the second rotating shaft 4e of the rotor 4 has a bearing on the member 10.
It is rotatably supported by a second bearing 10a provided in the.

The bearing member 10 is made, for example, by integral molding of plastic, and includes a bearing 10a that pivotally supports the second rotating shaft 4e of the rotor 4, and first to fourth holes 10f! ,10m,Ion,
10o. 1st to 4th holes 10A, 10m, I
on, '10o, the above-mentioned 1st. Terminals 8c, 8d, 9c, 9d of the second armature coils 8, 9 are guided to the back surface of the bearing member 10, and the flexible printed circuit board 11
connected to. The flexible printed circuit board 11 is connected to a drive circuit (not shown).

The bearing has first to fourth protrusions 1°b, 10 on the member 10.
d, 10f, and 10i (the second protrusion 10d is not shown), and each protrusion has first to fifth hooks 10c, 10e, 10g, 10h, and 10j (the second hook 10e is (not shown) is provided. The first to fifth hooks 10c, 10e, Log, 10h, 10j are
5I! grooves 5g, 5q, and 5 provided in the fixed ring 5 and having the first to fifth steps, respectively. The bearing member 10 is fixed to the fixing ring 5 by engaging with the step hook and locking the step hook. At this time, the bearing is positioned in the direction perpendicular to the optical axis of the member 10 by the first positioning pin 5f of the fixing ring 5, and the bearing is positioned in the first positioning hole 10p1 of the member 10.
The second positioning pin 5p of the fixing ring 5 and the second positioning hole 10q of the member 10 are fitted into each other, respectively.

Next, according to FIG.
The phase relationship between the magnetic pole parts 6a and 6c of the second stator 7 and the first and second magnetic pole parts 7a and 7c of the second stator 7 will be explained.

As mentioned above, each of the magnetic pole parts 6a and 6c, 7a and 70 has an opening angle of 90' in electrical angle, and the first magnetic pole part 6a and the second magnetic pole part 6c of the first stator 6 are mutually 180 in electrical angle
° Spaced apart. Further, the first magnetic pole part 7a and the second magnetic pole part 7c of the second stator 7 are also at an electrical angle of 18e0.
They are separated.

Further, the first magnetic pole part 6a of the first stator 6 and the second magnetic pole part 7c of the second stator 7 are separated from each other by 630 degrees in electrical angle, which is different from the first magnetic pole part 6a of the first stator 6. 6 and the second stator 7 is 90°, and the well-known two-phase stepping motor driving method (1
-2-phase excitation.

(two-phase excitation, etc.), the aperture device can be driven to a predetermined aperture value or returned to the open position in response to commands from the camera.

Next, the cogging torque of the stepping motor which is the drive source of the electromagnetic drive exposure amount adjusting device according to the present invention will be explained with reference to FIGS. 2 and 3.

When the second stator 7 is removed from the state shown in FIG. 2 and the cogging torque is measured, the cogging torque acting between the first stator 6 and the rotor 4 is
It exhibited characteristics as shown by A in the figure. However, the horizontal axis in FIG. 3 is the rotational position of the rotor 4 expressed in electrical angle.

Furthermore, when the first stator 6 was removed and the cogging torque was measured, the cogging torque acting between the second stator 7 and the rotor 4 exhibited characteristics as shown by B in Fig. 3. . Furthermore, the first. When measuring the cogging torque with both the second stator 6 and 7 attached, the third stator
The characteristics were as shown by AB in the figure. As is clear from this characteristic, the stepping motor that is the drive source of the electromagnetic exposure amount adjusting device according to this embodiment has a stable stopping position due to the cogging torque twice the number of magnetized poles during one revolution of the rotor 4. However, the position is equivalent to the one-phase energization position.

[Other Examples]

In the embodiment of the present invention described above, the rotor magnet was magnetized to eight poles, but the electromagnetic drive exposure amount adjusting device according to the present invention naturally has four or more magnetized poles. If so, it is possible.

Moreover, although the above embodiment is an example of an aperture device used for an interchangeable lens of a -eye reflex camera, it is obvious that it can also be used as a shutter device of a compact camera.

〔Effect of the invention〕

As explained above, the electromagnetic drive exposure amount adjusting device according to the present invention can achieve two stable stopping positions using a large amount of cogging torque.
This can be achieved by dimensional stator arrangement, so even during long exposure, the battery will not be exhausted.
This has the effect of easily and stably obtaining high aperture accuracy.

Further, in the electromagnetic drive exposure amount adjusting device according to the embodiment,
It is possible to obtain strong torque by using polar anisotropic magnets so that the stator for each phase collects magnetic flux from adjacent magnetic poles of the rotor magnet.
This has the effect that even a large-diameter aperture device can be easily driven.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of an electromagnetic drive exposure amount adjustment device embodying the present invention, FIG. 2 is an explanatory diagram of a portion of a stepping motor that serves as the drive source of the electromagnetic drive exposure amount adjustment device according to the present invention, and FIG. FIG. 3 is an explanatory diagram of cogging torque of the electromagnetic drive exposure amount adjusting device according to the present invention. 1...Cam member 2...Shading blade 3...Rotating ring 4...Rotor 5...Fixing ring 6.7...Stator 10...Bearing is a member

Claims (2)

[Claims] (1) In an electromagnetic drive exposure adjustment device having at least a plurality of light shielding blades and a stepping motor serving as a drive source for opening and closing the light shielding blades, the stepping motor has 2n poles (n=2, 3, . . .
), and first and second stators having first and second magnetic poles having an opening angle of approximately 90 degrees separated by approximately 180 degrees in electrical angle, The electrical angle of the first and second stators is (90+180
An exposure amount adjusting device characterized in that the exposure amount adjusting device is arranged at a distance of ×m)° (m=0, 1, 2, . . . ). (2) The exposure amount adjusting device according to claim (1), wherein a groove is formed in the rotor in the axial direction between each magnetized pole.