JPH0258035A - Motor-driven exposure adjusting device - Google Patents

Abstract

PURPOSE:To form a driving part in miniature and with a small diameter by constituting a step motor with a magnetic rotor, flat yokes crimping it and electromagnetic coil arranged between the yokes. CONSTITUTION:The step motor which turns a light shielding blade 3 is constituted of the magnetic rotor 9 multipolar-magnetized in an axis direction, two pieces of flat stator yoke 4a and 4b which crimp the rotor 9 in the axis direction and have a bearing part 4e, and two electromagnetic coils 8 which are arranged between the stator yokes facing a rotor central axis. The coils 8 are provided with power sources and a pair of magnetic poles are generated in the yoke part 4a of a stator 4. The generated magnetic poles and the magnetized magnetic pole of the rotor 9 are operated and the rotor 9 is rotated. Then a stop blade 3 is opened and closed via pinion gear 12. Thus the motor driving part is formed to be flat and miniaturized and its diameter can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to photographing devices such as still cameras, video cameras, cine cameras, and television cameras, and particularly to an electric exposure adjustment device for adjusting exposure.

[Background of the invention] Non-interchangeable lens cameras (especially 35mm still cameras)
is generally called a compact camera, and is equipped with a lens shutter device that functions as both a shutter and an aperture as an exposure control device.

In recent years, devices that use piezoelectric elements to perform drive control have appeared in these devices, but in the past, so-called electromagnetically driven shutters that utilize electromagnets have become mainstream. On the other hand, the applicant has proposed a 35mm still camera that incorporates an electromagnetically driven aperture into the interchangeable lens of an eye reflex camera (for example, Japanese Patent Laid-Open No. 62-2409
No. 42). This device has a different concept from the aperture control method used in conventional single-lens reflex cameras. In other words, the aperture value calculated by photometry in the camera is transmitted to the lens side as an electrical signal, and based on this signal, an electric exposure adjustment device mounted within the lens is controlled.

(Problem to be solved by the invention) In principle, this electromagnetically driven aperture is controlled by a stepping motor, but the space for the stepping motor becomes a problem.
It is very difficult to incorporate the lens barrel without increasing the outside diameter, and the disadvantage is that the lens barrel structure becomes complicated.

(Means for Solving the Problems) The present invention provides an electric exposure adjustment device that can be incorporated without increasing the outer diameter of the lens barrel. It is characterized by comprising a magnet rotor magnetized in the direction, a plurality of stator yokes bearing the rotor and holding the rotor in the axial direction, and an electromagnetic coil disposed between the stator yokes.

〔Example〕

A detailed explanation will be given below according to the drawings.

1 to 3 are embodiments of the present invention, and FIG. 1 is an exploded perspective view of a driving portion of the present invention.

Reference numeral 1 denotes a case of an aperture unit constituting a driven portion, and integrally has a column 1a. Reference numeral 2 denotes a driven member, which is a rotating ring having a gear 2a and a hole 2b into which a dowel 3a of the aperture blade 3 is inserted. 4 is a stator made of electromagnetic soft iron, which includes yoke parts 4a, 4b, a space 4c,
It has a hole 4d, a bearing hole 4e, a coupling hole 4f, and a positioning hole 4g, and is held in the case 1 by inserting the positioning hole 4g into the column 1a. Reference numeral 5 denotes a contact pin which is integrally attached to the bobbin 7, and the end portion of the winding in the coil 8 is soldered to one end.

An iron core 6 passes through the center of the coil 8. A screw hole 6a is formed in the center of the iron core 6.

Reference numeral 9 denotes a magnet rotor, which is magnetized with multiple poles in the axial direction, and has grooves 9a in the radial direction near the center of the magnetic poles. 1
A rotor shaft 0 is fixed to the magnet rotor 9 and rotatably supported by bearings 4e of the stator 4 at two locations. Reference numeral 11 denotes washers, which are rotatably arranged with respect to the rotor @ 10, one each on the upper and lower sides (in the axial direction) of the rotor, in order to maintain a space between the magnet rotor 9 and each yoke portion 4a, 4b of the upper and lower stators 4. There is. A binion gear 12 is fixed to the rotor shaft 10 by press-fitting or the like, and meshes with a large gear 2a integrally formed on the rotary ring 2. 13 and 14 are screws that connect the stator 4 and the iron core 6 to close a magnetic path.

Reference numeral 15 denotes a flexible printed board, which is attached to the four surfaces of the stator by screws 13. Reference numeral 15a indicates a land portion of the pattern on the flexible printed board 15, into which the contact pin 5 is inserted and fixed with solder.

Next, the operation of the above configuration will be explained in detail.

Power is supplied from the flexible printed board 15, and the power is supplied to the coil 8 through the contact pin 5.

When a current flows through the coil 8, a magnetic field is generated at both ends of the iron core 6. At this time, since the stator 4 is fixed to the iron core 6, magnetic poles that are the same as those generated at both ends of the iron core 6 are generated in the stator 4 as well.・Two stators 4 sandwiching a magnetic rotor
Since each yoke part 4a and 4b in has the same shape,
Magnet rotor 9 different poles (S or N 4M
) are facing each other. On the other hand, the bearing 4e of the stator 4
The gap between each yoke portion 4a centered on is the same as the magnetization pitch P of the magnet rotor 9. Similarly, the other yoke part 4b
The gaps between them are also the same pitch P. Furthermore, the positional relationship between the yoke portions 4a and 4b of the stator 4 is shifted by P/. Specifically, when the magnetized position of the magnet rotor 9 faces one yoke part 4a, the other yoke part 4b is arranged so as to face the boundary between the poles of the magnet rotor 9. Here, the functions of each part of the stator 4 will be explained in detail. The magnetic field generated by the iron core 6 is transmitted to the stator yoke parts 4a and 4b. Each yoke portion 4a, 4b in the stator 4 is connected to a magnet rotor 9.
Adjust the shape of the hole 4C so that the area is 70 to 80% of the area of one pole magnetized. In addition, the plurality of holes 4b are provided so that the magnetic field passing through each yoke part 4a, 4b does not go to the other yoke part (if yoke part 4a, yoke part 4b, yoke part 4b).
b) is formed on the yoke portion 4a) to increase magnetic resistance. By providing this hole 4d, two yoke parts 4a and 4b are provided despite the stator 4 being one piece.
This makes it possible to fulfill the role of

The pair of magnetic poles that have passed through the yoke portion 4a of the stator 4 interact (repulse, attract, etc.) with the magnetic poles magnetized in the axial direction of the magnet rotor 9, and provide rotational force to the magnet rotor 9. Further, the grooves 9a provided in the radial direction near the center of the magnet rotor 9 are for providing a harmonic component to the magnetic field to stabilize the stopping position in the non-energized state. Specifically, this is done to make the magnetization waveform closer to a trapezoidal waveform.

By sequentially switching the current direction of the two coils 8, it is possible to rotate them in a constant direction or in a reverse direction. This energization method is the same as that of a conventional stepping motor, and is not the gist of the present invention, so a description thereof will be omitted here.

The pinion gear 12, which rotates integrally with the step-driven magnet rotor 9, rotates the rotating ring 2 by a predetermined angle by rotating the gear 2a, which is a driven gear.

By the rotation of the rotating ring 2, the aperture dowel 3a is moved in the rotational direction. The other dowel 3b attached to the aperture blade 3 swings the aperture blade 3 in the opening direction or the closing direction due to its relative relationship with a fixed cam groove (not shown) provided in the case 1. Opens and closes the diaphragm.

The drive unit is positioned and fixed by fitting the hole 4g of the stator 4 and the shaft 1a in the case 1.

FIG. 2 is a sectional view of the motor drive section. Further, the operation will be explained with reference to the sectional view of FIG.

By energizing the coil 8, a magnetic field G is generated in the iron core 6, which passes through one stator 4, interacts with the magnetic field of the magnet rotor 9, and forms a closed magnetic path with the other stator 4. If the other coil 8 is not energized at this time, the magnetic path generated by the energized coil 8 becomes dominant, causing the magnet rotor 9 to generate rotational torque. In addition, the field coil in which both coils 8 are energized similarly forms a magnetic path in the upper and lower stators 4, and the magnet rotor 9
Similarly, the magnet rotor 9 receives a rotational torque. By energizing one or both of the coils 8 while sequentially switching the current direction, a conventionally known step motor is driven. The driving method will be omitted.

FIG. 3 is an overall perspective view of an electric exposure adjustment device incorporating the above-mentioned step motor. It can be seen from the figure that the drive section is flat and compact.

The effects of the embodiment described above are as follows.

■ Two stators that are originally separate parts,
By making the bearing into one component, it is lightweight, thin,
A low-cost unit was constructed.

■ The stop position, which is an important element of a step motor, is -
A yoke portion 4a of the stator 4 having a simple planar shape;
4b, it is easy to achieve high precision (the precision is mostly determined by the precision of the parts by pressing).

(2) The magnet rotor is multi-pole magnetized, and because of the multi-pole magnetization in the axial direction, it is easy, inexpensive, highly accurate, and can obtain high surface magnetic flux.

■ Since the two stators 4 have the same shape, it is possible to process them at the same time, and there is no variation between parts, and it is easy to determine the stator position during assembly, creating a step motor with less step angle error. I can do it.

■ The two stators 4 have two yoke parts 4a and 4b.
The various magnetic circuits are composed of a bearing hole 4e where the rotation center of the magnet rotor 9 is located, each yoke portion 4a,
By providing the hole 4d between the yoke 4b and the yoke 4b, the magnetic flux passing through one yoke part (for example 4a) does not reach the other yoke part (for example 4b), so efficiency can be greatly improved. Ta.

■ Step motor configuration 4, 8.9, 10. When assembling the stator 4, the stator 4 is assembled to the column 1a of the case 1, which improves the ease of assembly and reduces the number of parts. It was possible to improve the accuracy of the meshing position with 2a.

〔Effect of the invention〕

The present invention can provide an electric exposure adjustment device that can particularly reduce the outer diameter.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of essential parts of an embodiment of the present invention. FIG. 2 is a sectional view of FIG. 1. FIG. 3 is an external perspective view of an electric exposure adjustment device according to an embodiment of the present invention. 1... Case 2... Rotating ring 3.
...Aperture blades 4...Stators 4a, 4b
...Yoke part 8...Coil

Claims (2)

[Claims] (1) An electric type having a central axis in the direction of the optical axis that is eccentric with respect to the optical path hole that is opened and closed by a plurality of light shielding blades, and a step motor for rotational drive located outside the optical path hole. In the exposure adjustment device, the step motor includes a magnet rotor that is magnetized with multiple poles in the axial direction, at least two stator yokes that sandwich the magnet rotor in the axial direction and have bearings, and the stator yoke. An electric exposure adjustment device comprising at least two electromagnetic coils disposed facing each other with the magnet rotor as the center. (2) The electric exposure adjustment device according to claim 1, wherein a plurality of holes are formed in the stator yoke between a bearing hole serving as the bearing portion and the stator magnetic pole portion.