JPS59116629A - Driving device of photographic lens - Google Patents

Abstract

PURPOSE:To reduce the driving quantity of a lens unit to reduce the power consumption, by providing springs which hold the lens unit at the middle point of the driving range together with a cylindrical movable coil member and providing a fixed focus at the middle point of the lens unit. CONSTITUTION:A lens unit 29 is pressed backward by a spring 31 and is pressed forward by a spring 32, and the lens unit 29 is held at the middle point of a driving range P-P' of the lens unit 29 by both springs 31 and 32 when electric power is not supplied to a cylindrical movable coil member 15, and the fixed focus of the lens unit 29 is provided in this middle point. The current direction of power supply to the cylindrical movable coil member 15 is changed to move the lens unit 29 forward or backward for the focusing operation; and thus, the device is made small-sized easily because a special control mechanism is not necessary, and the focusing operation from the infinite distance to the closest distance is performed with a small driving quantity to enhance the power saving effect.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photographic lens driving device that drives a lens in a unidirectional manner using electromagnetic force to enable single focusing operations.

Conventionally, when driving a lens unit for focusing, etc., there have been two methods: one using a motor as a driving source, and the other using an electromagnetic force as a driving source. In the former case, the lens shank is used in cameras, and after shooting is complete, the shooting lens is spring-biased to an infinite distance position when the film is being wound, and distance measurement (F) is applied during shooting.
One method is to drive the photographic lens by driving a motor to the position determined by i, and the other is to drive the photographic lens by changing the rotation amount and direction of the motor according to the distance measurement signal, as seen in the ΔF device of an eye reflex camera. There were several methods, but all of them require gear reduction devices and devices that convert rotary action to linear action, etc., so it is difficult to get silk into modern cameras, which are becoming smaller and lighter. There was one. In addition, in the case of 1 many 1 A, since it is the electric θ driving J method, the moving coil member has 7 [i current direction,
Since everything can be controlled with one control, the number of control stages when driving the photographic lens is reduced.

Although the control circuit and control #3M structure were simplified, the conventional electric
In the case of the drive device, the fixed permanent magnet and the moving coil part were arranged to face each other in a plane, so a device to convert the rotational motion of the moving coil member into linear drive was still required, and miniaturization was required. Not only is there a limit, but like in the case of conventional motor drive, the photographing lens has an infinite speed ratio δ1 [
The method of driving the moving coil to a closer distance was adopted as is, and although it required a large driving force, the effective length of the coil was reduced in order to provide the space necessary for the optical system in the center of the moving coil member. It could not be made large enough, and therefore the driving force was weak and it could not function satisfactorily.

In view of the above points, this invention eliminates the inefficient and complicated drive system that converts one rotational motion into linear motion, and enables direct linear drive by electromagnetic force.
By making the lens unit small and lightweight, increasing the driving force, holding the lens unit at the midpoint of its driving range, and setting the midpoint at the normal focal point or overuse point position.

Reduces the amount of drive J in the lens unit to improve power saving.
At the same time, it is an object of the present invention to provide a photographic lens driving device capable of minimizing adverse effects on photography even if the movable coil member is not energized due to an electrical failure.

Next, the present invention will be described based on an embodiment shown in the accompanying drawings.

Reference numeral 1 denotes a lens barrel, and a cylindrical yoke 2 provided with a groove 2a is fixed to the inner surface of the base of the lens barrel 1. 3
．． Reference numeral 4 designates fixed permanent magnets disposed in a cylindrical shape in two inner and outer holding cylinders 5.6 which are fitted into the groove 2a of the cylindrical yoke 2 with a certain gap p between them. , 4 are not shown, but they may themselves be cylindrical. It is necessary that the facing surfaces of the fixed permanent magnets 3 and 4 facing inside and outside have different polarities. Reference numeral 7 denotes a lens frame for rear lens groups 8a and 8b, and the lens frame 7 is slidably supported by a flange portion 2b provided on the inner diameter surface of the cylindrical yoke 2 via a ball hair ring 9. . 10 is a spacer that holds between the rear lens groups 8a and 8b; 10a;
1 is a holding member for the rear lens groups 8a and 8b, and 11 is a holding member for preventing the ball bearing 9 from falling off. 12 is a support plate for the shutter 13, and the support plate 12 is connected to the lens frame 7.
It is integrated with the 14 is the shutter plate 1
It is a cylindrical body protruding from the rear surface of 2, and is fitted into the gap β between the inner and outer fixed permanent magnets 3 and 4.

15 is the cylindrical body 14 and a coil 16 wound around its outer circumference.
The cylindrical moving coil member 15 is linearly moved in the axial direction by electromagnetic force when the coil 16 is energized. 17 is the front lens group 18
In the lens frames a and 18b, the lens frame 17 is slidably supported on the inner diameter part of a cylindrical frame 19 fixed to the inner surface of the tip of the lens barrel 1 via a ball bearing 20. 21
is a front frame that also serves to prevent the ball bearing 20 from falling off;
22 is a lens front group 18a.

This is the holding member 18b. 23 is the above-mentioned Sha Tsuta-13
The fixed permanent magnet 23 is arranged in a holding frame 24 that is integrated with the front group lens frame 17. 25 is a yoke attracted to the front surface of the fixed permanent magnet 23 for driving the shutter, and 26 is a yoke provided 4k behind the fixed permanent magnet 23 with a certain gap therebetween. A plurality of plate-shaped movable coil members 27 and 28 are interposed within the gear between the fixed permanent magnet 23 and the yoke 26. Then, the plate-shaped movable coil member 27. .

One of the shutters 28 functions as a shutter drive, and the other functions as a control. 29 is the rear group lens frame 7
and the front group lens frame 17 are connected and integrated via a connecting member 30, and the lens unit 2
9 C. The circular ff1r-shaped movable coil member 15 is driven back and forth as it moves linearly in the axial direction by electromagnetic force when energized. The driving range of this lens unit 29 is the inner end surfaces 5a and 6a of the holding cylinders 5 and 6 that hold the fixed permanent magnets 3 and 4.
It is defined in the range P-P' where P is a shallow black and the inner end surface 19a of the cylindrical frame 19 fixed to the inner surface of the tip of the lens barrel l is simply P'. 31 is the lens unit 29
A spring 32 presses the lens unit toward the rear.
One spring 31. is a spring that presses the throat 29 forward.
32 is balanced, and when the cylindrical movable member is in a non-energized state, the lens unit 29 is moved within its drive range P-
It is held at the midpoint of P'.

Next, the operation of the camera incorporating the photographic lens driving device according to the present invention will be explained.

First, when you point the camera at the subject and press the release button (not shown), the distance measuring circuit (not shown) etc. determines whether the in-focus position of the optical system of lens unit 29 is at normal focus or It is determined whether the object is at close range δ1j or far away. In the case of close range, the coil 16 is energized to move the two cylindrical movable coil members 15 forward.

As a result, the lens unit 29 moves forward against the spring 31, and the yoke 25 that forms the front end of the lens unit 29 moves forward.
is the inner end surface 19a of the cylindrical frame 19.

That is, it is fixed in contact with the pixel point P'. On the contrary, in the case of a long distance, the cylindrical movable coil member 15 moves backward, and the lens unit 29 moves backward against the spring 32.
The shutter support plate 12 forming the rear end of the lens unit 29 is fixed in contact with the inner end surfaces 5a and 6'-a of the cylindrical yokes 5 and 6, that is, the rear end P. This lens uni 71-2
Moving the cylindrical moving coil member 15 forward and backward is carried out by changing the direction of current when energizing the cylindrical moving coil member 15. It goes without saying that the direction of this current is determined by the polarity of the fixed permanent magnets 3 and 4 arranged in a cylindrical shape.

In addition, when the focusing position of the optical system is at the normal focal position, the position where the balance of the blades 31 and 32 is maintained is maintained, so that one cylindrical movable coil member 15 has CP[J
Due to a control error (shown in the figure), the power is not energized.

When the lens unit 29 operates like a subunit and the first in-focus position is determined, an exposure signal is sent by an exposure control circuit (not shown), and the plate-shaped movable coil members 27 and 28 are energized to maintain a constant focus position. The shutter 13 comes to operate according to the aperture value and the second control I/roll.

After completing the exposure control, the cylindrical movable coil member 15
When the power to the lens unit 29 is cut off, the spring 31
or 32, it is returned to the midpoint (initial position) and waits for the 9th photographing.

As described above, according to the present invention, there are two fixed permanent magnets arranged in a cylindrical shape, and a fixed permanent magnet is fitted into the fixed permanent magnets.

Since it is provided with a cylindrical movable coil member that moves linearly in the axial direction when energized and a lens unit that is driven integrally with the cylindrical movable coil member, the lens unit can be used for focusing operations. The device for moving back and forth is extremely simple and does not require any special control mechanism, so it can be easily miniaturized and can be accommodated in a lens barrel.

In addition, since it is a combination of two cylindrical fixed permanent magnets and a cylindrical moving coil member, the effective length of the coil is increased to 11 J compared to the conventional electromagnetic drive device, and in the same magnetic field, Even if the same current is consumed, the driving force is much greater (the efficiency also increases).

Furthermore, in this invention, when the cylindrical movable coil member is in a non-energized state, a spring is provided to hold the lens unit at the midpoint of its drive range.
It is sufficient to move forward and backward with the midpoint as the initial position, and focusing operations from the eyeless speed ratio of 811 to close range are possible with less driving time, and in addition to being highly energy-saving, there is also a release button. This has various excellent effects, such as shortening the time from when the camera is operated to when focusing is completed.

Furthermore, according to the present invention, since the normal focus is provided at the midpoint where the lens unit is held by the springs, it is not necessary to energize the cylindrical moving coil member in general photography, which reduces current consumption. Not only can a large power saving effect be expected, but even in the unlikely event that the cylindrical moving coil is not energized due to an electrical accident, it has various excellent effects such as minimizing the negative effects on photography. It is something.

Since the present invention has the above-described configuration, it can be easily applied not only to focusing and sweeping a photographic lens, but also to collapsing devices, zooming, etc., as long as the device can move in a straight line.

Further, in the above-mentioned embodiment, the rear group lens frame and the front group lens frame are integrated in the lens unit 1-, but it goes without saying that either one of them may be used.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which FIG. 1 is a cross-sectional view of the main part in the direction of the optical axis, and FIG. 2 is a cross-sectional view of the main part in the direction perpendicular to the optical axis. 3.4-- Fixed permanent magnet 15- Cylindrical moving coil member 29- Lens Uniso 1- 31.32-Spring Patent applicant Roku Konishi Photo Industry Co., Ltd. Procedural pressure letter (method) Patented on April 28, 1982 Agency Commissioner Kazuo Wakasugi 1 - Indication of the case Patent Application No. 225058 of 1982 2 - Name of the invention Photographic lens drive device 3 - Person making the correction Relationship to the case Patent applicant address 1 Nishi-Shinjuku, Shinjuku-ku, Tokyo Chome 26-2 Name
Konishiroku Photo Industry Co., Ltd. Representative Nobuhiko Moto 4-Agent ■151 Address 2-5-1-6 Yoyogi, Shibuya-ku, Tokyo ? i
lt Positive subject Application and specification 7-? ili Correct contents of application and specification (no change in contents) 179-

Claims (1)

[Scope of Claims] A fixed permanent magnet arranged in a cylindrical shape, a cylindrical moving coil member that fits into the fixed permanent magnet and moves linearly in the axial direction during one energization, and is integrated with the cylindrical moving coil member. The lens unit y l is driven by. What is claimed is: 1. A photographic lens driving device comprising: a spring for holding the lens unit at the midpoint of its driving range; and a focal point is provided at the midpoint of the lens unit.