JPS58122522A - Structure of photographic lens driven by electromagnetic force - Google Patents

Abstract

PURPOSE:To drive an aperture device arranged in a photographic lens with the driving force of a motor, by controlling the operation of the operating member of the aperture device by the electromagnetic induction action and detecting a value corresponding to the diameter of aperture blades as an electric signal. CONSTITUTION:The aperture device of a lens structure is normally held in the fully opened position by a spring stretched on an aperture operating member. A proper aperture value is calculated in an operating circuit on the basis of a release operation; and when power is supplied to a field coil 20 through an electric signal terminal 24 and a lead wire 26, the electromagnetic induction acts across the coil 20 and a permanent magnet, and a movable ring member 22 is turned around the optical axis through an arm 22a to turn the aperture operating member. The size of the aperture diameter of aperture blades is detected as an electric signal proportional to it by a rotation position detecting means 30 or the like, and the turning of the aperture operating member is stopped on the basis of the output signal of this detecting means.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a lens structure that drives the movable part of a photographic lens by electromagnetic induction, and also uses the driving force of a motor to drive an aperture device disposed inside the photographic lens. purpose. Furthermore, in the present invention, an operating member that applies rotational force to the aperture blades forming the aperture aperture is connected to a rotating part of a motor, and when the operating member is rotated by the electromagnetic induction action of the motor, the operating member is set at a rotation reference position. A means for detecting the amount of rotation from the diaphragm blade is provided, and a signal from the enclosure that calculates the aperture value to obtain the appropriate exposure amount according to the shooting conditions on the camera side is provided to determine the aperture of the aperture blade that is actually apertured. The present invention aims to provide a device for controlling the aperture blades to an appropriate aperture diameter by comparing the aperture information and adjusting the forward and reverse rotation of the motor.

Furthermore, the present invention detects a change in the amount of rotation of the actuating member as an electric signal by means of a magnetoresistance conversion element or the like, and detects a value corresponding to the aperture diameter of the aperture blade in the rotating part of the actuating member, and adjusts the aperture aperture to a desired value. The object is to provide a diaphragm device that can be accurately controlled.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.FIG. 1 to FIG. An example of driving the device is shown. In the figure, 2 is a fixed barrel of the lens structure 1, and the fixed barrel 2 is an interchangeable lens barrel, and the fixed barrel 2 is an interchangeable lens barrel. - Providing a known mounting (coupling) means 4 such as a screw mount. 6 is a double helicoid tube screwed into the inner part of the fixed tube 2, and the photographing lens group L1-. It is screwed together with the movable cylinder 8 that holds Ls. The double helicoid tube 6 is connected to a focus operation member 10 by screws or the like, and a key member 12 attached to the fixed tube 2 is engaged with a vertical groove 81 provided in the movable tube 8.

The movable cylinder 8 has an aperture unit case 14. Throttle actuating member 16. An aperture device consisting of aperture blades 18, etc., and a permanent magnet M1. A part of the motor consisting of the field coil 20 and the like and a device 28@50 for detecting the rotating lid of the aperture operating member are arranged.

Unit case 14. Aperture blade 1B, aperture operating member 16
uses a known structure, with shaft pins (shown in S) erected on both sides of several iris-type aperture blades 18, each of which is connected to a hole in the unit case 14 and the aperture actuating member 16. The aperture actuating member 16
The aperture diameter is formed at the end face of the aperture blade 18 by rotation around the optical axis. The rotation detection device for a part of the motor and the diaphragm actuating member will be explained in detail with reference to Fig. 1 and Fig. 2 a*bic.

8b is a cylindrical member fixed to the movable tube 8 and has a rectangular cross section, and a movable ring member 22 is fitted into this cylindrical member 8b so as to rotate smoothly around the optical axis by means of a ball bearing 24. ing. The outer periphery of this movable ring member 22 is
A letter-shaped arm member 22m is attached, and a bar-shaped permanent magnet M1 is fixed to the arm member 22a. This permanent magnet M1 is inserted into a hollow field coil 20 attached to the cylindrical member 8bK.

This field coil 20 is not only a part of the fixed cylinder 2, but also has an image from a camera shown in the figure! fA device and the lens 1
The structure is configured such that power can be supplied via a lead wire 26 from a power supply terminal 24 provided on a mounting surface 21 that serves as a mounting portion for coupling.

, the lead edge 26 is omitted from FIG. 2C.

As shown in FIG. 2 1b, a pin 16a is attached to the movable ring member 22 and the aperture actuating member 16 as a means for mutual connection. The diaphragm actuating member 16 is rotated accordingly. The rotation IEIImm rotation means of the diaphragm actuating member 16 around the optical axis is constructed as follows. The rotation M detection means utilizes a type of magnetoresistive detection means, and a substantially arc-shaped plate member 28 is attached to the outer periphery of the movable ring member 22.

This plate member 28 is processed with a magnetic recording medium.

This magnetic recording medium is made of a magnetic material such as a magnetic tape and has a length l attached to the plate member 28, and the magnetic material is magnetized with magnetism that changes in a constant relationship as K from the magnetic tape toward lb. A detection element mounting plate 60 (shown in Figure 2 CK) is located at a position facing the magnetized surface of the plate member 28.
Place. This mounting plate 30 is fixed to the cylindrical member 8b with screws 52.

A magnetoresistive element (MR element) is fixed to the mounting plate 50, electrodes are provided at both ends of the magnetoresistive element, and leads [34 for passing current are connected to the element.

This lead l1R54 receives power for supplying power to a portion of the motor.

When the MR element receives leakage magnetic flux from the recording medium, the direction of magnetization of the element rotates due to the perpendicular component of the magnetic flux, and the direction of the current changes at an angle corresponding to the amount of magnetic flux. Therefore, the electric current at both ends of the MR element rotates. The resistance value changes, at the end of which the magnetic symbol signal on the recording medium can be read out as a voltage signal. Therefore, when the movable ring member 22 rotates due to the electromagnetic guiding action of a part of the motor, the recording medium also rotates, and the change in the amount of rotation from the reference position of the movable ring member 220 causes a resistance value at both ends of the MR element. It appears as.

Next, FIG. 5 shows a control circuit for controlling the operation of the motor part and rotation detecting means of the lens structure shown in FIGS. 1 to 2 a*b.

In the figure, F is luminance information By and film sensitivity information Sv
- An exposure calculation circuit that calculates aperture information Fv to be controlled by appropriately inputting photographing information such as shutter time information Tv. C.P.
1.CF2 is a comparison circuit that inputs signals from the arithmetic circuit F and rotation detection means P and compares the two signals.The output signal of the comparison circuit is input to the servo amplifier AP1.Ar1, and the comparison circuit CP1・CF2 inputs the output signals of the arithmetic circuit F and the rotational position detection means P, respectively, and if the input signal from the arithmetic circuit F is larger than the input signal of the rotational position detection means P, the transistor 'l of the servo amplifier AP is input.
'r1 is made conductive, and the field coil 20 of the motor is turned on.
Electricity is applied to act on 5 to further rotate the opening movable member 22 around the optical axis. Moreover, when the input signal from the rotational position detection means P is larger than the input signal of the arithmetic circuit F,
The transistor Tr2 of the amplifier 5AP is made conductive a,
A current is applied in the opposite direction to the coil 20 of the motor to allow the movable ring member 220 to freely rotate in the rotational direction.

When the signal of the arithmetic circuit F and the signal of the rotational position detector M; tP become equal, and the aperture value based on the input photographing information and the aperture value of the aperture of the aperture device become equal, the motor stops its operation.

The operation of the lens structure having the above structure will be described. The lens structure 1 is attached to a single-lens camera, a camera for video equipment, etc., and power is supplied from the main body of the equipment through the terminals 24 and 6. For focusing operation, when the focus operation member 10 is rotated around the optical axis, the double helicoid cylinder 6 and the key member 120
Due to this action, the movable barrel 8 moves straight in a direction parallel to the optical axis, and focusing is performed by the lens groups L1 to L5.

Photometering circuit and film sensitivity input setting means on the equipment side.

By operating the exposure time setting means, the B, S, and T
Appropriate exposure input information such as v is set, and based on this, the aperture aperture to be controlled by the aperture device is calculated. On the other hand, since the aperture device of the lens structure 1 is normally held at the fully open aperture position by the spring 3B stretched between the aperture operating member 168 and the movable member 8, the rotational position of the movable member 1122 can be detected. The means P outputs an electric signal representing opening of the aperture.

The calculation circuit F calculates an appropriate aperture value based on the operation start operation (release operation) on the device side, and the electric signal terminal 24. By energizing the field coil 20 through the lead wire 26, an electromagnetic induction effect acts between it and the permanent magnet M1, and the movable ring member 22 rotates around the optical axis via the arm 22a. Since the movement simultaneously moves the aperture actuating member 16 through the connecting means 22c and 16a, the aperture blades reduce their aperture diameter in response to the rotation fK of the movable member 220.

The size of the aperture diameter of the aperture blades is determined by the rotational position detection means P (28,
60), it is output as an electrical signal proportional to the size of the aperture aperture. The output signal from the rotational position detection means P is converted by the conversion means Fp into an aperture signal corresponding to an aperture aperture value according to the rotational position of the movable ring member 22.

Then, the aperture value signal Fv calculated in Ail and the aperture signal Fpv corresponding to the ever-changing aperture aperture are input to a comparison circuit, and the transistor Tr1 of the servo amplifier AP is turned on during the time when the calculated aperture value is smaller. This outputs a signal that energizes a portion of the motor to reduce the aperture diameter of the aperture device. When the calculated aperture value and the aperture diameter of the aperture device match, the output signal of the comparison circuit CP is not output (the power supply to the motor is stopped and the aperture device stops in that state. If the narrowing is too narrow, the comparison circuit CP outputs the servo amplifier A.
A signal is output that makes the transistor Tr2 conductive, and a current in the opposite direction is supplied to a part of the motor, which rotates the movable ring member 22 in the opposite direction to the above-mentioned direction, and rotates the aperture operating member 16 in the reverse direction to adjust the aperture diameter. Acts in the direction of opening.

In FIGS. 1 to 2 1 and b, the motor part M1
・Although only one 20 is shown in the diagram, it is possible to arrange *a pieces to increase the rotational force of the movable ring member, or to provide four motors and drive two of them in the narrowing direction and drive the other 22 in the reverse direction. Operation performance can be improved by using it for purposes.

Further, it is also possible to use a motor as shown in FIG. 5 as an example of controlling the rotation of the diaphragm actuating member around the optical axis by electromagnetic induction.

@5 In Figure 5, the same reference numerals as in the above embodiment indicate the same parts.

Reference numeral 40 denotes a bobbin made of a non-magnetic material, and the cylindrical portion of the bobbin 40 is rotated by holding members 42a and 42b, and the coil end is fixed by the same method as IJ-do@26 in FIG. 1 of the first embodiment. Powered. An arc-shaped permanent magnet M1 is inserted inside the hollow coil 46, and this permanent magnet M1 is held by arm members 48a-48bK attached to the movable ring 22KkGt. Movable ring 22
The permanent magnet M1, which is fixed and inserted into the hollow coil 46, can swing within the hollow coil, and this bobbin,
field coil.

Another set of tortoise guide means consisting of a permanent magnet and an armature is provided at a distance of about 180 degrees from the center of the optical axis.

50 is a member for holding a magnetoresistive element (MR element), which is attached to the movable ring member 22; 52 is a magnetic recording medium of a magnetic tape thickness processed so that the magnetic strength increases stepwise; 52m, and the cylindrical member 8b
can be attached to.

In the case of the example shown in FIG. 5, the permanent magnet M is not supported in a cantilever but supported at both ends, so the movable ring member 22 and the crest actuating member 1
60 rotations are performed smoothly.

When manually controlling the operation of the aperture device of the lens structure shown in FIG. The movable ring member 22 is rotated by the rotation of the manual aperture setting/gage 54, whereby the aperture blades are manually adjusted via the aperture operating member 16. Furthermore, this manual aperture signal is sent to the camera@
In order to send the signal to the user, a signal transmitting arm member may be provided from the movable ring member 22.

As described above, the present invention can provide a technique that enables more accurate exposure control by controlling the operation of an aperture device within a lens structure by electromagnetic induction and by applying it to a lens.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a lens structure according to an embodiment of the present invention. FIG. 2a is a perspective view showing a unit portion of the aperture blades 18 and the aperture operating member 16. FIG. 2 is a perspective view showing the arrangement and structure of a part of the motor for generating electromagnetic conduction force and a means for detecting the rotational position of the throttle actuating member. FIG. wJ4 is a diagram showing another configuration of the electromagnetic induction generating means, and is an explanatory diagram in which the cylindrical member 8b and the movable ring member 22 of FIG. 1 are attached in a plan view. 8... Movable cylinder 8b... Cylinder member attached to the movable cylinder 8 14... Aperture unit case 16... Aperture operating member 22... Movable ring member 26-34---IJ
-)'# 20-46--3 for field a M...
·permanent magnet. Applicant: Canon Co., Ltd. Canon Seiki Co., Ltd.

Claims (1)

[Scope of Claims] 1) A means is provided for driving an operating member that controls opening and closing of the aperture blade with a rotational force generated by electromagnetic induction and detecting an electric signal corresponding to the aperture diameter of the aperture blade, and an output of the detection means. A 1111i force-driven photographic lens body, characterized in that the rotation of the actuating member is stopped based on a signal. 2) The means for detecting the electric signal according to the aperture diameter of the aperture blade is constituted by magnetoresistance converting means provided on a fixed part of the photographic lens structure and a rotating member that rotates by electromagnetic induction. An electromagnetic force-driven photographing lens structure according to claim 1.