JPS61221715A - Motor built-in lens barrel - Google Patents

Abstract

PURPOSE:To build a motor for focusing and a motor for stop adjustment in a lens barrel as a compact and lightweight structure by constituting both motors in hollow cylindrical shapes and building them in the lens barrel inside and outside concentrically, utilizing them so that they are operatively associated with an optical member for focusing and a stop adjusting member, and providing a rotation control member common between both motors. CONSTITUTION:A motor M2 having a hollow cylindrical field coil 23 and a motor M1 having a hollow cylindrical permanent magnet 24 are held in the fixed cylinder 1 of the lens barrel L so that they rotate concentrically. Either motor is associated helicoidally with the holding member 27 of an optical element G5 for focusing and the other motor is coupled with as top device 13 to make a stop adjustment. Rotations of the field coil 23 of the motor M2 and the permanent magnet 24 of the motor M1 are controlled alternately by a rotation control means 40(P). Consequently, an automatic focusing and automatic stopping compact device is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention [Field of Industrial Application] The present invention relates to a lens barrel incorporating a single focusing motor and an aperture adjustment motor.

[Conventional technology]

Conventionally, as a drive system for automatic focus adjustment, a small coreless motor or coreless motor is installed on the outer periphery of the focus adjustment (hereinafter abbreviated as "focusing") lens and aperture blade, which are the driving targets, and a gear unit is used. Predetermined adjustments are made via deceleration means such as. Therefore, the lens drive system including the motor protrudes from the outer periphery of the lens body, which is undesirable in terms of appearance and operation.

In that case, the aperture drive system uses a mechanical transmission means such as a lever M-pin to transmit the signal from the camera body side to the aperture blades, as is well known, and these levers, pins, etc. This placed restrictions on the structure of the mount that connects the body and lens barrel, and was an obstacle to the development of new camera systems.

Therefore, proposals have been made for a motor structure in which a hollow cylindrical motor is built into the lens barrel and a focusing lens or aperture blade is disposed in the hollow part of the motor, and a lens barrel with a built-in motor.

[Problem that the invention seeks to solve]

However, if the drive motors for focusing and aperture adjustment are built in separate locations, not only will they require space, but the motor and optical system, including position detection sensors for drive control, will need to be installed. This creates new constraints on the layout of the lens barrel, making it difficult to make the lens barrel body smaller and lighter.

The present invention solves the above-mentioned drawbacks and at the same time provides a novel driving system for a lens barrel with a built-in motor by unitizing the focus adjustment and aperture adjustment mechanisms.

1. Structure of the Invention [Means for Solving Problems] The present invention has a hollow cylindrical focusing motor and an aperture motor arranged inside and outside concentrically within a lens barrel, and focusing optical elements, respectively. The holding member and the diaphragm adjusting member are interlocked, and a rotation regulating means for the motor is further provided so that when one motor is regulated, the regulation of the other motor is released.

[Function] A focusing motor and an aperture adjustment motor are configured in a hollow cylindrical shape and are built into the lens barrel concentrically inside and outside, and are linked to the focusing optical member and the aperture adjustment member respectively to form a unit. Since the motor is provided with a common rotation regulating member, it can be incorporated into the lens barrel in a compact and lightweight manner.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings.

In Fig. 1, the reference numeral indicates the entire lens barrel, M indicates the motor unit arranged inside the fixed barrel 1 of the lens barrel, and la indicates the motor unit for attaching the lens barrel to the camera body (not shown). A bayonet member 2 at the rear end of the fixed barrel 1 is a fixed barrel connected to the fixed barrel L, and a fixed lens G is attached to the tip of the fixed barrel.
Attach 1. The rear end side of the fixed cylinder 2 is a cylinder part 2A.
B has multiple layers. 4 is the inner cylinder part 2
A cam cylinder 6 disposed on the outer periphery of A is a zoom ring fitted to the outside of the fixed cylinder 1 and 2 so as to be rotatable around the optical axis, and is engaged with the cam cylinder 4 via a pin 8. ing.

Reference numerals 10 and 12 are lens holding frames holding a variator lens G2 and a compensator lens G3, respectively, and a key portion 1'0a that engages with a straight groove 2a provided in the inner cylinder portion 2A.
s12a, and further includes a cam groove 4 provided in the cam cylinder 4.
Cam followers 10b-12b engaged with a and 4b, respectively.
has. Reference numeral 13 denotes an aperture blade unit disposed at the tip of the fixed cylinder 1 or the rear end of the fixed cylinder 2, and has a rotating pin 13a fixed to a well-known aperture blade drive link member not shown in the figure. Reference numeral 14 denotes an inner fixed cylinder part disposed inside the fixed cylinder l, which holds the fixed lens G4 and also holds the motor unit M. A key 15 is also provided for moving a focusing lens G5, which will be described later, in a straight line.

FIG. 2 shows an enlarged view of the motor unit (M), and FIG. 3 is a sectional view taken along the line AA in FIG. 2, particularly showing the rotation regulating device section. Identical members are indicated by the same symbols in each figure.

In FIG. 2, 20 is an outer cylinder which is a fixed part of the motor unit)M, and 22 is an outer cylinder 2 which is connected to the outer cylinder through bearing parts 21a and 21b.
22a is an aperture adjustment lever attached to the rotor 22, and 26 is a focus adjustment rotor rotatably supported by the outer cylinder 20 via bearings 25a and 25b. A field coil 23 is embedded in the rotor, the aperture adjustment rotor 22, and is energized via an electric wire (not shown). The outer periphery of the focus adjustment rotor 26 is made of a material.

A permanent magnet 24 made of, for example, a ferrite or rare earth element is fixed thereto, and forms a magnetic circuit together with the outer tube 20 and the focusing rotor 26.

This example shows the structure of a coreless motor M2 (22, 23) that rotates back and forth through a limited angle for aperture adjustment, and a brushless motor M1 (26-24) that rotates multiple times for focus adjustment. Since the drive circuit is well known, a description thereof will be omitted.

Incidentally, a sensor 31 for detecting the position of the rotor 26 of the brushless motor M1 is fixed to the rotor 22 via a sensor holding part 30. In order to detect the rotational position of each rotor, for example, a pulse plate 33 is disposed on the outer periphery of the rotor 26 so as to rotate together with the pulse plate 33, and a pulse reading sensor 32 is disposed on the sensor holding portion 30.

The focusing lens G5 is connected to the rotor 2 of the focusing motor M1.
6 and a key groove 2 that is helicon-coupled with the key 15 and is fitted with the key 15.
It is fixed to a focusing lens holding frame 27 having a diameter 7a, and as the rotor 26 rotates back and forth, it moves in a reciprocating straight line together with the holding frame 27.

In FIG. 3, reference numeral 40 denotes a plunger body P disposed on the outer cylinder 20, which moves the movable lever 41 linearly to one side when energized; the movable lever 41 moves linearly to one side when energized; One brake shoe 43 restricts the rotation of the rotor 22 by engaging with the other brake shoe 43.
is a brake force transmission lever 42 whose support point is the bin 42a.
is fixed with a bottle 43a. Further, the lever 42 is connected to a movable lever 41 via a pin 41a, and when the current is applied, the brake shoe 43 is pressed toward the center of the motor, causing friction with a brake drum 28a arranged in a ring shape around the outer periphery of the rotor 26. The rotation of the rotor 26 is restricted by the force.

The operation of the lens barrel configured as described above will be explained based on the system diagram in FIG. 4 and along the timing chart in FIG. 5.

In Fig. 4, A is the camera body, Al-A2 is a ranging signal circuit from a well-known ranging system and an aperture signal circuit from an automatic exposure system, and B is a signal from a ranging switch/release button (not shown). According to the above A1 and A2
Plunger P and focusing motor Ml (24
・26), a discrimination circuit that drives the aperture motor M2 (22, 23), C is the distance measurement signal AI, aperture signal A2
and a comparison calculation circuit for signals from an encoder E that detects the rotational position of the driven rotor, and D is a drive circuit that drives the M1 and M2 using the signal from the comparison calculation circuit.

First, attach the lens barrel to the camera body, set the subject, and press the distance measurement switch (Figure 5a).At this time, plunger P
is not energized, and the rotation of the rotor 22 of the aperture adjustment motor M2 is regulated as described above, resulting in the open aperture value. The rotor 26 of the focus adjustment motor M1 is rotatable. The reflected light from the subject that has passed through the photographic lenses 0-ri to G5 enters a distance measuring device (not shown) in the camera body and is subjected to calculation processing, after which the moving direction and distance are determined from Al as distance measurement signals by a discrimination circuit B and a comparison calculation circuit. The power is transmitted to the drive circuit via C, and the field coil 23 is energized to drive the focusing motor Ml (focus adjustment rotor 26), and the key 15 moves the holding frame 27 that holds the fixed lens G5 in a linear direction. Drive helicoid. This driving of the fixed lens G5 in the linear direction is continued until it is determined that focusing is completed based on the feedback signal from the encoder E and the signal from the AI. Note that the above-mentioned distance measurement method and focus display method are well known and will therefore be omitted.

After focusing is completed, the plunger P is energized and the aperture adjustment motor M is activated.
The rotation restriction of the rotor 22 of No. 2 is released, and the rotation of the rotor 26 of the focusing motor M1 is restricted to maintain focus and become ready for exposure (FIG. 5b).

At the same time as the release button is pressed, the aperture signal processed by the exposure device in the camera body (not shown) is transmitted from A2 to the drive circuit via the discrimination circuit B and comparison arithmetic circuit C, and is transmitted to the field coil 23 of the aperture motor M2. To energize K
The rotor 22 is further driven, and the aperture blades 13 are operated via the lever 22a to narrow down the aperture (Fig. 5 c-d).
).

After the aperture blades are closed, the shutter in the camera body (not shown) is moved (FIGS. 5e to 5f).

Next, after the completion of shutter travel, that is, the end of exposure, the field coil 23 is energized in the direction in which the aperture opens, the aperture motor M2 is reversed to the initial aperture opening position, and the plunger P is de-energized to open the aperture adjustment rotor 22. Rotation is restricted at the aperture open position, and the focus adjustment rotor 26 is in its initial rotatable state (Fig. 5 gh).

In the embodiment, the motor M2 having a permanent magnet 24 is used for focusing, and the motor M1 having a field coil 23 is used for adjusting the aperture. May be used.

However, in that case, the motors M1-M2 are reversed.

In this embodiment, the rotational position of the rotor is detected by the sensors 31, 32. Although the pulse plate 33 is used as an optical system, a magnetic system such as a known multi-pole magnetized magnet and a Hall element or an MR element may also be used.Alternatively, a mechanical system using friction as shown in the figure may be used as a rotation regulating device. Alternatively, an electric solenoid may be used to attract the rotor directly, which eliminates mechanical wear problems and increases reliability.

The rotation angle of the aperture motor M2 should be as small as possible because of the electric wires connected to the field coil 23, position detection sensor 31, and pulse reading sensor 32, but the rotation angle of the aperture motor M2 should be as small as possible because of the electric wires connected to the field coil 23, position detection sensor 31, and pulse reading sensor 32. For example, if the angle of rotation is limited to 30 degrees or less, and if a rotation angle of 1800 degrees is obtained with the structure of the present invention, the aperture value accuracy will be six times higher, which will improve the accuracy of the known aperture device.

C1 Effect of the invention As described above, the motor M2 having the hollow cylindrical field coil 23 and the motor M1 having the hollow cylindrical permanent magnet 24 can be rotated concentrically in the fixed barrel 1 of the lens barrel. One motor is helicoidally linked to the holding member 27 of the focusing optical element G5 to adjust the focus, the other motor is connected to the aperture device 13 to perform the aperture tl1 section, and the motor M2 The rotation of the field coil 23 and the permanent magnet 24 of the motor M1 is alternately restricted by the rotation restriction means 40(P), thereby making possible a compact automatic focusing and automatic aperture device. Particularly in the aperture device, a mechanical drive transmission mechanism between the camera body and the lens barrel, such as an aperture lever, in the conventional structure is no longer necessary, resulting in the effect that a new camera system can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a lens barrel according to an embodiment of the present invention in the optical axis direction, FIG. 2 is an enlarged partial view of the motor unit M in FIG. 1, and FIG. 3 is an A-A in FIG. 2. Line cross section, 4th
The figure is a drive system diagram for focus adjustment and aperture adjustment of the present invention, and FIG. 5 is a drive timing chart. L... Lens barrel, l... Its fixed part 1M... Motor unit, Ml... Motor with hollow cylindrical permanent magnet 24, Ml... Hollow cylindrical field coil 23 Motor held, G5...Focusing optical element, 14...
The holding member, 13... Aperture mechanism, 13a, 22a,
... Aperture adjustment member, 40 (P) ... Rotation regulating means.

Claims (1)

[Claims] (1) A motor with a hollow cylindrical field coil and a motor with a hollow cylindrical permanent magnet are held in a fixed part of the lens barrel so that they can rotate concentrically, and one of the motors is connected to the focusing lens. The other motor is helicoid-coupled with a holding member of the element, and the other motor is linked with an aperture adjustment member disposed within the lens barrel, and both motors are provided with a common rotation regulating means, so that when one of the motors is regulated, the other is regulated. A lens barrel with a built-in motor, characterized in that the motor is configured in such a manner that the motor is released.