JPH03171121A - Diaphragm device - Google Patents

Abstract

PURPOSE:To reduce the thickness of the above device and to improve the efficiency of utilizing the space in a lens barrel by oscillating a driving lever within the plane perpendicular to an optical axis, transmitting the movement thereof to diaphragm vanes and switching the diaphragm to be positioned on the optical axis to different diameters, thereby changing the aperture diameter. CONSTITUTION:A magnetic circuit is formed of coils 14, 15 having the central axis parallel with the optical axis and magnetic materials 8 to 11 spaced and disposed to face each other in the optical axis direction. The driving lever 16 is magnetically moved within the spacings between the magnetic materials by this magnetic circuit and further, this movement is transmitted to the diaphragm vanes 3 by which the diaphragm to be positioned on the optical axis is switched to the different diameters to change the aperture diameter. The driving part of the diaphragm vanes 3 is, therefore, formed thinner than the conventional diaphragm device and the size in the optical axis direction of the diaphragm device is shortened. Thus, the efficiency of utilizing the space when this device is built into the lens barrel is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an aperture device for a photographic lens used in various photographic devices.

[Prior Art] Conventionally, an aperture device such as an iris diaphragm, in which the aperture diameter changes continuously from the maximum aperture to the minimum aperture, has been widely used as the aperture of a photographic lens.

However, when a more accurate aperture diameter is required, or when it is necessary to simplify the aperture mechanism and downsize the aperture device, a light-shielding thin plate with a fixed diameter aperture can be used in a plane perpendicular to the optical axis. A diaphragm device is used that obtains a necessary aperture diameter by moving the diaphragm in and out of the photographing optical path.

Examples of such a diaphragm devices include one in which one or more apertures with different diameters are provided in a long thin light-shielding plate and the aperture diameter is changed by sliding the aperture in a direction perpendicular to the optical axis, or a circular plate. There is one in which holes with different diameters are provided around the circumference of the disk, and the aperture diameter is changed by rotating this disk in a plane perpendicular to the optical axis.

FIG. 3 is a plan view of a conventional aperture device that uses electromagnetic drive to drive a light-shielding thin plate.

In the figure, 3l is a diaphragm blade made of a ladle-like light-shielding thin plate with a circular head, which is arranged along with the main plate 37 in a plane perpendicular to the optical axis, and the end of the part that corresponds to the handle is attached to the bottle 3.
2, it is rotatably held on the main plate 37. The circular head is provided with openings 31a and 3lb having different diameters.

Further, between the pin 32 and the opening 31a in the handle of the aperture blade 3l, there is provided a long hole 31c that is elongated in the axial direction of the handle, into which a pin 34 (described later) is slidably fitted. ing.

Reference numeral 36 denotes a return spring, one end of which is fixed to the base plate 37, and the other end fixed so as to rotate the aperture blade 3l clockwise in the figure.

On the other hand, the pin 35 is fixed to the base plate 37, and determines the limit position of the clockwise rotation of the aperture blade 31 by the biasing force of the spring 36, thereby determining the position of the aperture blade 31.

The main plate 37 has an aperture 37a on the photographing optical axis indicated by a dotted line.
is provided, and normally overlaps the opening 31a to form an open aperture diameter.

Further, a plunger device 33 that is a driving device for the aperture blade 31 is provided on the main plate 37, and its structure is similar to that of the fourth
As shown in the cross-sectional view of the figure, a cylindrical coil 46 is installed inside a magnetic case 4l that forms part of a magnetic circuit, and an iron core 43 is attached to a guide member at its central axis. 44, and is slidably fitted in the axial direction of the coil 4l, that is, in the direction perpendicular to the optical axis. Further, a pin 34 is fixed to the end of the iron core 43, and is fitted into the elongated hole 31c. Note that 45 is a magnetic cover and 42 is case 4.
This is a magnetic yoke fixed at 1.

The aperture device having such a configuration is operated by energizing the coil 46 during an exposure operation or the like. That is, the iron core 43 is attracted to the yoke 42, which causes the aperture blades 3
l is pulled downward in the drawing by the bottle 34 against the force of the spring 36, and the head of the aperture blade 31 is further rotated counterclockwise in the drawing so that the aperture 3lb overlaps the center of the aperture 37a, and a predetermined aperture is formed. The diameter is obtained. When the current to the coil 46 is cut off,
The aperture blade 31 returns to its initial position due to the bias of the spring 36, and the aperture 31a becomes heavier than the aperture 37a again.

[Problems to be Solved by the Invention] However, although this throttle device has the advantage of simplifying the throttle mechanism and making the device smaller, the thickness of the iron core and coil of the plunger device (in the direction perpendicular to the plane of the drawing) It is difficult to reduce the size (dimensions) beyond a certain limit and make it flat. Therefore, when the conventional diaphragm device is incorporated into a camera, lens, etc., its front axis dimension cannot be reduced beyond a certain limit, and the space cannot be used effectively.

An object of the present invention is to solve the problems of the conventional device as described above, to replace the above-mentioned plunger type mechanism for driving the aperture blades, and to shorten the dimension of the aperture device in the optical axis direction. The object of the present invention is to provide an aperture device that can improve space utilization efficiency when it is incorporated into a lens barrel, for example. [Means for Solving the Problems] The diaphragm device of the present invention that achieves the above object is characterized by having at least one static position set in a plane perpendicular to the optical axis by magnetic attraction and a return position by a spring. a driving member movable between the plurality of positions; a spring means for elastically stopping the driving member at the return position; Aperture blades that switch the aperture diameter by switching one of a plurality of apertures provided on the optical axis, and a gap opened in the optical axis direction into which a part of the driving member can be moved and fitted are arranged on the magnetic axis. and a magnetic circuit forming means for providing a stationary position by attraction, the magnetic circuit forming means including a coil having a central axis parallel to the optical axis, and the driving member is magnetically attracted by excitation of the coil. The object is to be brought to a rest position by the above-mentioned magnetic attraction.

[Function] According to the present invention configured as described above, the present squeezing device has the following functions:
A magnetic circuit is formed by a coil having a central axis parallel to the optical axis and magnetic bodies placed facing each other at a distance in the direction of the optical axis, and the driving member is magnetically moved within the gap between the magnetic bodies by this magnetic circuit. By adopting a configuration in which this movement is transmitted to the aperture blades and the aperture diameter is changed by switching the aperture located on the optical axis to a different diameter C, the driving part of the aperture blades is thinner than in conventional aperture devices. This makes it possible to reduce the size of the aperture device in the optical axis direction.

[Example] The present invention will be explained in detail below based on an example shown in the drawings. FIG. 1 is an exploded perspective view showing the configuration of an example of the diaphragm device according to the present invention. The device in this example is composed of a base plate, a driving member that can be moved in a plane perpendicular to the optical axis, a leaf spring that serves as a return spring, aperture blades that change the aperture diameter, and magnetic circuit forming means. One of its features is that the switching of the aperture diameter is controlled by the drive. The magnetic circuit forming means in the wooden example includes two coils l4 and 15 having central axes parallel to the optical axis, and one coil block 7 that holds these coils in parallel in a direction perpendicular to the optical axis.
and a pair of yokes arranged with a predetermined gap between the coil and the coil block, and these members form the first and second two magnetic circuits. ．． That is, the first magnetic circuit includes a coil l4 fitted into the hole 7b of the coil block 7, a yoke 12 fitted to the central axis of the coil l4, and a coil l4 and the coil block 7 sandwiched between them. A pair of yokes 8, 1 arranged so that
Similarly, the second magnetic circuit consists of a coil 15 fitted into the hole 7c of the coil block 7, and a coil 15 fitted into the hole 7c of the coil block 7.
It consists of a yoke l3 fitted to the central axis of the coil block 7, and a pair of yokes 9 and 11 arranged to sandwich the coil block 7.

Note that the second magnetic circuit has the same components and structure as the first magnetic circuit, so in the following description, for the sake of simplicity, the configuration of the first magnetic circuit will be used. I will omit the explanation by giving a detailed explanation. The coil block 7 is made of a non-magnetic material such as plastic, and is provided with a hole 7b into which the coil l4 is fitted and a hole 7C into which the coil 15 is fitted. Also, coil block 7
The part facing the yoke lO has a recess 7d for crimping and positioning the yoke lO when assembled, and similarly the part facing the yoke 11 has a recess 7d for crimping and positioning the yoke lO. ! A recess 7e is provided for crimping and positioning. In addition, a recess (not shown) is provided on the back side of the recess 7d of the 5-il block 7 for crimping and positioning the yoke 8, and a recess (not shown) is provided on the back side of the recess 7e for crimping and positioning the yoke 9. (not provided) is provided. Note that 7a is a threaded portion, which serves as a nut portion for a screw 6, which will be described later.

The coil 14 has a cylindrical shape and is fitted into the hole 7b of the coil block 7. A yoke 12 passes through a central hole 14a provided in the direction of the optical axis. The end 12a of this yoke l2 is the yoke lO
The structure of the coil 15 is the same as that of the coil 14, and the end portion 12b is press-fitted into the hole 8a of the yoke 8. The yokes 8, 9, 10 and 11 are flat magnetic bodies,
The yoke 8 and the yoke 10 are disposed facing each other with a gap open in the optical axis direction.

And each projecting end portion 8b, 1 of the yoke 8 and lO
0b are faced with a predetermined gap, and due to this gap,
A first spatial position is provided in which a portion of the driving member, which will be described later, is magnetically attracted and becomes stationary. Further, the gap between the projecting ends of the yokes 9 and 11 similarly provides a second spatial position in which the drive member is magnetically attracted and comes to rest. The magnetic circuit type control means is fixed to a cover 4, which will be described later, with screws 6, sandwiching the base plate 1 and the aperture blades 3. That is, the hole 4a of the cover 4,
A screw 6 passes through the hole 5a of the spacer 5 and the hole IC of the base plate 1, and is screwed into a nut of the threaded portion 7a of the coil block 7, thereby assembling and fixing each of these members.

Next, the main plate 1, the aperture blade 3, the cover 4 and the spring 2
To briefly explain 0, the main plate 1 is made of a non-magnetic material, and has holes 1d and 1e for attaching this device to the camera body perpendicular to the optical axis, a hole 1g whose center coincides with the optical axis, and the functions described below. Hole 1a, hole 1b, hole IC, long hole 1
f is provided.

The aperture blades 3 are formed of a light-shielding thin plate, and have an aperture aperture 3b for a small aperture, an aperture aperture 3C for a large aperture, and a long hole 3d and a hole 3a having the functions described below. It is rotatably supported by the diameter portion 2b. The pin 2 has its large diameter portion 2b inserted into the hole 4b of the cover 4, and its small diameter portion 2a inserted into the hole 4b of the cover 4.
The ends of the aperture blades 3 are press-fitted into the holes 1b of the base plate 1, and the aperture blades 3 are held in a space formed by the base plate 1 and the cover 4 so as to be able to swing in a plane perpendicular to the optical axis.

Reference numeral 4 designates a cover, which is arranged perpendicular to the optical axis and is provided with an opening 4a having a diameter slightly larger than the hole 1g of the base plate, a hole 4b having a function described later, a hole 4d, and a long hole 4C. Furthermore, the bent portion 4e provided at the end of the cover 4 is
Together with the spacer (washer) 5, it forms a gap between the base plate 1 and the cover 4. Reference numeral 20 denotes a spring means composed of a plate spring, which functions as a return spring for the drive lever 16, which will be described later. Further, a bent portion 20b for fixing to the base plate 1 is provided at one end of the leaf spring 20, and a semicircular convex portion 20a that comes into contact with the cam portion 18b of the drive lever 16 is provided near the other end.

On the base plate 1, a drive lever l6 is attached to an axis l7 parallel to the optical axis.
It is rotatably supported. This drive lever 16 is provided with an armature portion 16a, which will be described later, which is moved into the gap of the magnetic circuit, so that the swinging motion of the drive lever l6 caused by this armature is transmitted to the aperture blade 3 via a pin 19. It has become.

That is, the drive lever 16 is formed of a flat plate of magnetic material such as electromagnetic soft iron, and has an arcuate edge portion on the annular outer periphery having a hole 16d, with which the convex portion 20a of the leaf spring 20 comes into contact. A cam portion 16b and a cross-shaped armature portion 16a that moves within the space of the magnetic circuit are provided. The drive lever 16 has a shaft l caulked and fixed in the hole 16d.
It is rotatably held on the main plate 1 by a holding plate 7 and a holding plate l8. The small diameter portion 17a and the small diameter portion 17b are the ends of the shaft 17, 18a is a hole in the holding plate l8 in which the small diameter portion 17a is rotatably held, and 18b is the end for fixing the holding plate 18 to the main plate 1. It is. The pin 19 for transmitting the movement of the drive lever l6 to the aperture blade 3 has a small diameter part 19a fitted and fixed in a hole 16c of a cam part 16b, and a large diameter part 19b connected to the long hole 1f of the main plate 1 and the aperture blade 3. By loosely fitting into the elongated hole 3d and the elongated hole 4C of the cover 4, the movement of the armature portion 16a is magnified and transmitted to the aperture blade 3 in the wooden example. Next, the operation of this device having such a structure will be explained based on FIG. 2.

In the figure, (a) is a state where only the coil 14 is energized, (b) is a state where the coils l4 and 15 are de-energized, and (C) is a state where only the coil 15 is energized. are shown respectively. First, the magnetic force is not working (
In the state b), since the drive lever l6 can freely rotate, the convex portion 20a of the leaf spring 20 stably abuts on the cam portion 16b at the most concave portion of its arched edge. Therefore, the armature portion 16a is located in the first position defined by the gap portions ab, tab as well as in the gap portions 9b, ll.
It is elastically rested in a return position intermediate said second position assumed at b. At this time, the bottle 19 fixed to the cam portion 16b slides to approximately the middle of the elongated hole 1f of the main plate 1, and the aperture blades 3 move in conjunction with this, and the aperture aperture 3b for the small aperture is opened in the main plate 1. It overlaps the center of the hole 1g (the position of the photographing optical axis).

Therefore, the aperture becomes small.

Next, in the state of (a) in which only the coil l4 is electromagnetized, the armature portion 16a is magnetically attracted to the coil 14 side against the bias of the leaf spring 20 and swings to the above-mentioned first position. sway to. Therefore, the large diameter portion 19b of the pin 19 has a long hole I.
f to almost the right end in FIG. 1, and in conjunction with this, the diaphragm blades 3 move to a position where they have evacuated the hole 1g of the main plate 1, and the diaphragm becomes in an open aperture state. When the current to the coil l4 is cut off, the cam portion 16b of the drive lever l6 is pushed by the convex portion 20a of the leaf spring 20 and moves to the return position, and the aperture blade 3 returns to the small aperture state of (b) above. to return to.

Further, in the state (C) in which only the coil 15 is electromagnetized, the armature portion 16a is magnetically attracted to the coil 15 side against the bias of the leaf spring 20 and swings to the second position. It moves. Therefore, the pin l9 slides in the elongated hole If to almost the left end in FIG.
(position of the shooting optical axis). Therefore, the aperture becomes a large aperture. When the current to the coil 15 is cut off, the state of the small aperture shown in (b) is restored again, similar to the state of (a) above. As described above, the drive lever l6 is swung between three positions, which causes the diaphragm blades 3 to oscillate and change the aperture diameter. In addition, in this embodiment, two sets of magnetic circuits are formed, and a return spring is used to move the drive lever l6 as shown in (a) above.
Although we have described an aperture device that is structured to move between the three positions (b) and (c), a drive lever is moved between the two positions (a) and (b) using a set of magnetic circuits and a spring. It is also possible to construct a diaphragm device that can be oscillated by.

[Effects of the Invention] As explained above, according to the present invention, the drive lever is oscillated in a plane perpendicular to the optical axis, and this movement is transmitted to the aperture blades to position the aperture on the optical axis. The aperture diameter is changed by switching the aperture diameter to a different diameter, and in order to drive the drive lever, the magnetic circuit forming means is configured using a coil whose central axis is parallel to the optical axis. This has the effect of reducing the size of the device in the optical axis direction, and, for example, when it is incorporated into a lens barrel, it has the effect of improving the space utilization efficiency within the lens barrel.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing an outline of the configuration of an example of the diaphragm device according to the present invention, and FIG. 2(a). (b). (c)
is an explanatory diagram of the main parts to explain its operation. Moreover, FIG. 3 is a plan view of an example of a conventional diaphragm device,
Figure 4 is a cross-sectional view of the drive section. l...Main plate 3...Aperture blade 4...Cover 7...Coil block 8, 9, lO, 11
, 12, l3...Yoke l4, l5...Coil l6...Drive lever 17...Shaft 20...Flat spring and 4 others

Claims (1)

[Claims] 1. A driving member that is movable between at least one static position set in a plane perpendicular to the optical axis by magnetic attraction and a return position by a spring, and the driving member a spring means for elastically stopping the aperture at the return position; and a spring means for elastically stopping the aperture at the return position, and switching one of the plurality of apertures provided at different diameters onto the optical axis in conjunction with the movement of the drive member between the plurality of positions. Aperture blades are positioned to switch the aperture diameter, and a magnetic circuit forming means is provided for providing a gap opened in the optical axis direction into which a part of the driving member can be movably inserted as a static position by the magnetic attraction. The magnetic circuit forming means includes a coil having a central axis parallel to the optical axis, and when the coil is energized, the driving member is magnetically attracted and brought to rest at a rest position above the magnetic attraction. A diaphragm device featuring: