JPH04271332A - Lens barrel - Google Patents

Abstract

PURPOSE:To lower the driving force of a motor and to allow the use of the compact motor by fixing a diaphragm member directly to the output shaft of the motor and turning this diaphragm member. CONSTITUTION:A diaphragm aperture 2b having an aperture diameter of 5.6 Fno and a diaphragm aperture 2c having an aperture diameter of 11 Fno are formed on the planar diaphragm member 2. The diaphragm fixing member 3 itself used for maintaining the output shaft 1a and the diaphragm member 2 at a fixed relation is fixed to the output shaft 1a of the motor 1. This diaphragm fixing member 3 and the diaphragm member 2 are frictionally coupled to allow the slip turning of the diaphragm member 2 relative to the fixing member 3. Further, a long hole 2a of an arc shape around the output shaft 1a is formed on the diaphragm member 2 and a fixing pin provided on the diaphragm fixing member 3 is fitted into this long hole 2a. Then, the diaphragm member 2 can be turned and adjusted by as much as the range of the long hole 2a. The motor 1 is disposed to face a holding member which holds a lens frame movably in the optical axis direction with the optical axis in-between.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel having an aperture having at least one aperture.

0002

2. Description of the Related Art Conventionally, an aperture device having a plurality of aperture diameters has been developed by attaching a pinion gear to the output shaft of a drive source, as described in Japanese Patent Application Laid-Open No. 63-220209.
Through this gear, a rack and a gear installed in the aperture member were driven.

FIG. 10 shows a conventional example where 101 is a motor and 10
3 is a pinion gear, 104 is a gear fixed to the aperture member 102, 102 is a aperture member having a plurality of aperture diameters,
106 is the front group barrel in the lens barrel, 107 is the rear group barrel, and 114, 115, 116 are the front and rear group barrels 106 and 1.
This is a zoom bar that holds 07.

In the above configuration, the motor 101 is driven by a control circuit on the camera side (not shown), and the aperture member 102 is moved to a predetermined rotational position via the pinion gear 3 and the aperture gear 4.

[0005]

[Problems to be Solved by the Invention] However, in the above conventional example, (1) the aperture member is driven through a gear, so the motor requires driving force to drive not only the aperture member but also the gear train. do. Therefore, the driving force must be increased by being larger than the motor that originally drives only the aperture member, or by using an expensive rare earth magnet.

(2) Since the diaphragm member is driven through a gear, the center of the diaphragm aperture shifts from the optical axis of the camera (of the film surface or imaging surface) due to the effect of backlash, which adversely affects the image plane illuminance. give.

[0007] Furthermore, if a biasing mechanism (using a spring or the like) is provided to eliminate the bump, the driving force of the motor must be increased accordingly.

(3) A bearing is required to hold the gear shaft installed in the diaphragm, which does not make the diaphragm mechanism compact and increases the size of the lens barrel itself.

(4) In order to keep the center of the aperture aperture aligned with the optical axis of the camera, the motor control circuit must be operated until the end of photography.

(5) The motor 101 is the zoom bar 1
It must be placed outside of 14 and 115. For this reason, the space in which the motor 101 is installed protrudes from the lens barrel, and other components of the camera must be spaced out accordingly. Further, when the lens barrel protrudes from the camera body, there is a drawback that the protruding portion of the motor 101 spoils the appearance of the camera.

(6) Since the zoom bars 114, 115 and 116 are opposed to the optical axis, the aperture member 2
rotation angle is limited.

0012

[Means for Solving the Problems] The present invention fixes a diaphragm member provided with an diaphragm aperture directly to the output shaft of a motor, positions the diaphragm aperture on the optical axis according to the rotation of the motor, and furthermore, It is characterized by a lens barrel in which the motor is placed at a position facing a holding member that holds the lens frame so as to be movable in the optical axis direction, with the optical axis in between.

[0013] This makes it easy to accurately align the aperture of the diaphragm member with the optical axis, and furthermore, it is possible to downsize the lens barrel itself.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 show only the aperture mechanism of a lens barrel according to a first embodiment. Reference numeral 1 denotes a motor for driving an aperture, and an output shaft 1a rotates. Reference numeral 2 denotes a plate-shaped aperture member, in which an aperture aperture 2b having an aperture of Fno. 5.6 and an aperture aperture 2C having an aperture of Fno. 11 are formed. 3 is an aperture fixing member, which connects the output shaft 1a and the aperture member 2.
It is used to create a fixed relationship between The diaphragm fixing member 3 itself is fixed (press-fitted or glued) to the output shaft 1a of the motor 1, and the diaphragm fixing member 3 and the diaphragm member 2 are frictionally connected, so that the diaphragm member 2 allows slip rotation. Note that the aperture member 2 is formed with an arc-shaped elongated hole 2a centered on the output shaft 1a.
A fixing pin provided on the aperture fixing member 3 is fitted into the elongated hole 2a. Therefore, the aperture member 2 has a long hole 2
Rotation adjustment is possible within the range a.

As shown in FIG. 2, the diaphragm member 2 is rotated by the drive of the motor 1, and the diaphragm member 2 is rotated between the "fully closed" and "F1" positions.
Four aperture value controls are available: "1 aperture", "F5.6 aperture", and "open".

Note that when a stepping motor is used as the motor 1, each of the aperture members 2 is adjusted so that each of the four phases shown in FIG. Set the aperture apertures 2b, 2c and outer diameter. Of course, it is also necessary to adjust the rotation of the diaphragm member 2 and to adjust the step angle and each of the above-mentioned phases.

If the aperture fixing member 3 is a plastic molded member, the fixing pin 3a can be used as a thermal caulking pin, and if the member 3 is metal, the pin 3a can be used as a caulking pin. Of course, the diaphragm member 2 may be fixed to the diaphragm fixing member 3 after rotation adjustment by adhesion.

What is characteristic about FIG. 2 is that when the diaphragm member 2 is in the fully closed state, the area without the diaphragm openings 2b and 2c is simply aligned with the optical axis, and when the diaphragm member 2 is in the open diameter state, the outer diameter of the diaphragm member 2 is aligned with the optical axis. The purpose is to shift the fan-shaped ridge line from the optical axis by at least the open diameter. Note that by not having a diaphragm opening corresponding to this opening diameter, there is an effect that the size of the diaphragm member 2 can be reduced.

FIGS. 7 to 9 show a lens barrel as a first embodiment, in which the diaphragm mechanism shown in FIGS. 1 and 2 described above is incorporated.

In the figure, 5 is a fixed front frame, 6 is a lens frame for the front group lens I (correction system), 7 is a lens frame for the rear group lens II (variable power system), and 8 is a lens frame 7k. A cam follower pin, 9 is a washer, 10 is a spring that presses the cam follower pin 7 against a surface cam portion 11a of a cam member 11 (to be described later) (enabling it to follow), 11 is a surface cam portion 11a
It is a cam member having a lead screw 13 described later.
Fixed. 12 is the mount, 13 is the lens frame 6
14 is a guide bar, 0-0
' is the optical axis.

The lead screw 13 and the guide bar 14 are supported by the front frame 5 and the mount 12, and hold the two lens frames 6 and 7 movably in the optical axis direction. However, the lead screw 13 is driven and rotated (not shown). The lead screw 13 rotates and the lead screw 13a
When the lead screw 13a is rotated, the ball 6a biased by a spring in the V-groove in the lead screw 13a moves in the optical axis direction, and the lens frame 6 supporting this ball also moves in the optical axis direction. Further, the cam member also rotates due to the rotation of the lead screw 13, and the cam follower pin 8 also follows in the optical axis direction due to the cam displacement of the surface cam portion 11a, and the lens frame 7 also moves in the optical axis direction, thereby performing zooming. be exposed. Note that the guide bar 14 is connected to the lens frame 6,
It serves only as a guide for the movement of the lens 7 in the optical axis direction.

As shown in FIG. 9, the motor 1 includes a lead screw 13 as a holding member for the lens frames 6 and 7;
It is arranged at a position facing the guide bar 14 across the optical axis 0-0'. Therefore, the motor 1 can be laid out without protruding from the lens barrel, and the diaphragm member 2 can be rotated at a large angle.

3 and 4 show a diaphragm mechanism section according to a second embodiment, in which the elongated hole 2a of the diaphragm member 2 shown in the first embodiment is replaced with a burring section 2d. The burring portion 2d is formed to be slightly smaller in diameter than the output shaft 1a of the motor 1, and the throttle member 2 is rotatably held on the output shaft 1a. After adjusting the rotation of the aperture member 2 with respect to the output shaft 1a, it is fixed with an adhesive or the like.

According to the second embodiment, the diaphragm fixing member 3 can be omitted, and cost effects and inertia reduction effects can be obtained.

FIGS. 5 and 6 show a diaphragm mechanism as a third embodiment, in which the diaphragm member 2 of the first embodiment is provided with a convex portion (or concave portion) 2e, and the adjacent lens barrel member is provided with a convex portion (or concave portion) 2e. Click recesses (or protrusions) 4a, 4b, 4c, and 4d are provided at intervals corresponding to the respective phases shown in FIG. The state in which the convex portion 2e of the aperture member 2 falls into the click concave portion 4d is “fully closed,” and the state in which the convex portion 2e falls into the concave portion 4c is “F”.
11", then "F5.6", and "open" are obtained. In this third embodiment, even if the motor 1 is de-energized, the aperture member 2 can be held at a position aligned with a predetermined aperture phase, which is particularly effective in reducing power consumption. or,
Even if the stopping accuracy of the output shaft 1a of the motor 1 is somewhat poor,
The click force ensures the accuracy of the stopping position of the diaphragm member 2.

[0026]

[Effects of the Invention] In the present invention, since the throttle member is fixed directly to the output shaft of the motor and the throttle member is rotated, the driving force of the motor can be reduced and a compact motor can be used. did. Furthermore, since no gears or the like are used for transmission, high precision can be achieved without causing bumps or the like, which is particularly important for an aperture mechanism that moves a fixed aperture aperture to align with the optical axis.

Furthermore, in the present invention, the rotation angle of the diaphragm member can be adjusted by arranging the motor at a position opposite to the holding member that holds the lens frame movably in the direction of the optical axis, across the optical axis. It is possible to obtain a large aperture value, increase the number of settable aperture values, and provide a compact lens barrel with no protrusions.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of only the aperture mechanism section of the first embodiment.

FIG. 2 is an explanatory diagram of the operation of the aperture mechanism section of the first embodiment.

FIG. 3 is a perspective view of only the aperture mechanism section of the second embodiment.

FIG. 4 is a side view of the aperture mechanism section of the second embodiment.

FIG. 5 is a side view of the aperture mechanism section of the third embodiment.

FIG. 6 is an explanatory diagram of the operation of the aperture mechanism section of the third embodiment.

FIG. 7 is a sectional view of the lens barrel of the first embodiment.

8 is a plan view of the lens barrel in FIG. 7. FIG.

9 is a front view of essential parts of the lens barrel in FIG. 7. FIG.

FIG. 10 is a perspective view of essential parts of a conventional lens barrel.

[Explanation of symbols]

1 Motor 2 Aperture member 2b, 2c Aperture aperture 6, 7 Lens frame 13 Lead Screw 14 Guide bar

Claims (4)

[Claims] 1. A lens barrel having an aperture member provided with an aperture, wherein the aperture member is directly fixed to the output shaft of a motor, and the aperture aperture is positioned on the optical axis in accordance with rotation of the motor. A lens barrel further characterized in that the motor is disposed at a position facing a holding member that holds the lens frame so as to be movable in the optical axis direction, with the optical axis in between. 2. The lens barrel according to claim 1, further comprising a positioning mechanism for positioning the diaphragm member during rotation, so that the stop position of the diaphragm aperture can be aligned with the optical axis. 3. The lens barrel according to claim 1, wherein the diaphragm member has a fully closed area in addition to the diaphragm opening. 4. The diaphragm aperture of the diaphragm member is set only to be smaller than the aperture diameter, and diaphragm control at the aperture diameter involves removing the diaphragm member from the optical axis. Or the lens barrel according to 3.