JPS6275608A - Lens power varying device - Google Patents

Abstract

PURPOSE:To form a thin device by providing a gear on the outside periphery of a cam cylinder which moves a moving lens and constituting a driving lever having a gear engaged with said gear so that this lever is rocked and freely moved forward and backward to follow up the cam cylinder. CONSTITUTION:A bevel gear 30A is provided on the peripheral surface of a cam cylinder 30 constituting a lens barrel 4 of a lens base 3, and this bevel gear 30A is engaged with a bevel gear 7A provided in the front end part of a rocking lever 7. The front end part of the rocking lever 7 is freely turnably connected to the lens base 3 through a pin 9, and a long hole 7B is formed in the other end part of the lever 7, and a pin 8A provided on a bracket 8 is fitted to the long hole 7B, and consequently, the lever 7 is guided by the pin 8A and is rocked and moved forward and backward in accordance with the extent of movement of the lens base 3 thereby, and the bevel gear 30A of the cam cylinder is turned by the bevel gear 7A, and the cam cylinder 30 is rotated to drive a variator lens in the cam cylinder 30.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a lens magnification device, and particularly to a lens magnification device that changes the magnification of an optical system in order to enlarge or reduce an image in an optical device such as a copying machine. Regarding.

[Background of the invention]

The lens system of the variable magnification mechanism in optical devices such as copying machines consists of a compensator lens and a variator lens.
The entire lens system is moved and the variator lens is moved to change the lens spacing, thereby enlarging or reducing the image. To move the variator lens, a cam follower is provided protruding from the outer periphery of the holding frame of the variator lens, and the cam follower is inserted into the cam of the cam tube, and the cam tube is rotated in conjunction with the movement of the lens system. , move the variator lens.

The following apparatus is conventionally known for changing the focal length of a lens by rotating the cam barrel as the entire lens moves.

(1) A lens magnification changing device (Japanese Patent Laid-Open No. 58-82275) in which a wire is wound around the outer periphery of a cam cylinder, the end of the wire is fixed to a housing, and the cam cylinder is rotated by movement of a lens system.

■The worm meshes with the worm gear on the outer periphery of the cam cylinder,
A lens magnification variable device that is connected to a rack installed in the housing via a pinion, and the movement of the lens system and the rotation of the cam cylinder are linked.

■A lens magnification device that rotates the cam barrel by moving the lens system by providing diagonal teeth on the outer periphery of the cam barrel and meshing with the diagonal tooth rack installed in the housing.

Generally, optical devices such as copying machines are required to be designed to have a low overall height. However, all of the conventional lens magnification changing devices have the disadvantage that the magnification changing mechanism cannot be made thin. Furthermore, in an optical system in which the mechanical distance from the document surface to the optical material is constant, and the lens moves to change the magnification, the focal length of the lens changes by a predetermined amount and the conjugate length remains constant. needs to be preserved. However, since lenses actually produced have variations in nominal preparation distance, the amount of change in focal length due to zooming must be adjusted for each lens. In the prior art, there is no mechanism that satisfies this requirement.

[Purpose of the invention]

The present invention has been developed in consideration of these circumstances, and the entire magnification changing mechanism can be made thin, and variations in the focal length of the lens can be reduced, making it possible to always form a well-focused image. The object of the present invention is to provide a lens magnification changer.

(Summary of the Invention) In order to achieve the above object, the present invention moves the entire optical system consisting of a lens group including a movable lens within a housing, and also moves the movable lens to change the lens interval of the lens group. In a lens magnification changer for changing the magnification of a system, a cylindrical body in which a linear guide groove is formed in the optical axis direction of the optical system;
A cam cylinder with a cam groove formed in the circumferential direction and a gear carved on the outer periphery, a lens holding frame that holds a movable lens, which is protruded outward in the radial direction, and a guide groove of the cylinder and a cam of the cam cylinder. A cam follower that fits into the groove and moves the lens holding frame in the optical axis direction as the cam barrel rotates, and a cam follower that is supported by the housing so as to be able to swing and move forward and backward, and that engages the gear of the cam barrel at the end. It is characterized by comprising a drive lever in which matching gears are formed and rotates the cam cylinder following the movement of the optical system, and a drive lever support part that supports the drive lever by making the swinging fulcrum of the drive lever movable. It is something.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a lens magnification changer according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows the general structure of a copying machine, in which the members designated by reference numeral 1 are the housing of the copying machine, 2 members, 2B a mirror, and 3 a lens stand. On the lens stand 3, a lens barrel 4 of a variable magnification optical system and a moving motor 5 are mounted.

A pinion 5A connected to the output shaft of the motor 5 meshes with a guide bar 6 formed with a rank 6A and moved obliquely. Therefore, when the motor 5 is driven and the pinion 5A is rotated, the lens stand 3 is reciprocated parallel to the axis of the guide bar 6. On the other hand, the direction of the reflected light from the document table (not shown) is changed by a mirror 2A, and after passing through the lens barrel 4 of the variable magnification optical system of the lens stand 3, the direction of the reflected light is changed by the mirror 2B, and the light is incident on an angry light drum (not shown). Lens stand 3: Move from the position indicated by the imaginary line on the left to the position indicated by the imaginary line on the right, and perform magnification conversion.

As shown in FIG. 2, a bevel gear 30A is carved on the circumferential surface of a cam barrel 30 (described later) that constitutes the lens barrel 4 of the lens stand 3, and this bevel gear 30A is attached to the tip of the swing lever 7. It meshes with the carved bevel gear 7A. The tip of the swing lever 7 is rotatably connected to the lens stand 3 via a pin 9. A long hole 7B is formed at the other end of the swing lever 7, and a pin 8A protruding from the bracket 8 is fitted into this long hole 7B, so that the drive lever 7 is guided by this pin 8A. The lens base 3 swings and advances and retreats according to the amount of movement shown in the image line in FIG. The variator lens within 30 can be driven. Further, the bracket 8 has a long hole 8a formed therein, and within the range of the long hole 8a, a bolt 8b installed in the casing can be screwed in and manually operated.

Next, the configuration of the lens barrel 4 of the optical system and the rotation mechanism of the cam barrel 30 will be explained. FIG. 3 shows the overall structure of the lens barrel 4 of the lens magnification changer according to the present invention, where 10 is a barrel;
2.0 is the variator lens holding frame, 30 is the bevel gear 30A
The cam cylinder is engraved with , 40 is the variator lens holding frame,
50 is a compensator lens holding frame. In FIG. 3, a compensator lens 12 is attached to the right end of the cylinder 10, and three linear guide grooves 14.1 are formed in the optical axis direction.
4.14 is formed. 3 Holding frame 2 that holds the variator lens 202.402 in correspondence with the wooden guide groove 14
There are three cam followers 208.2 on the outer peripheral surface of each 0.40 mm.
08.208.408.408.408 is provided protrudingly.

Further, in the circumferential direction of the cam cylinder 30, cam grooves 302, 302, 302, 304, 304, 30 in which a cam follower 208, 408 protruding from the outer peripheral surface of the holding frame 20, 40 is guided are formed.
4 is formed in three places. The holding frame 50 holds a compensator lens 502, a male threaded portion 504 is formed at the right end of the holding frame 50, and the holding frame 50 is adapted to be screwed into a female threaded portion 16 formed at the left end of the cylindrical body 10. ing.

The lens barrel of the zoom lens according to the present invention includes the above-mentioned barrel 10,
Consists of a holding frame 20, 40, 50 and a cam cylinder 30,
The holding frame 20.40 is attached to the cam groove 302.304 of the cam cylinder 30.
With the cam follower 208, 408 of the cam follower 208, 408 fitted, insert the cylinder 10 between the holding frame 20 and the cam cylinder 30 while fitting the cam follower 208, 408 into the guide groove 12 of the cylinder 10. Next, the male threaded portion 504 of the holding frame 50 is screwed into the female threaded portion 16 of the cylindrical body 10 to be assembled.

Further, the holding frame 20 is formed of a double structure of an outer frame 2OA and an inner frame 20B, and an eccentric pin 212 shown in FIG. 3 is pivotally supported. By rotating the eccentric pin 212 and tilting the inner frame 20B, the variator lens 202 can be displaced in the optical axis direction.

Although the lens holding frame 20 has been described in FIG. 3, the lens holding frame 40 is also constructed in exactly the same manner.

A preferred embodiment of the lens magnification changer according to the present invention constructed as described above will be described in detail. First, the motor 5 is driven,
When the pinion 5A is rotated, the pinion 5A is engaged with the rack 6A of the guide rod 6, so that the lens stand 3 moves in accordance with the magnification within the range shown by the left and right image lines in FIG. When the lens stand 3 moves, the bevel gear 30 of the cam barrel 30
Since A is meshed with the bevel gear 7A of the swing lever 7,
The cam cylinder 30 rotates according to the amount of movement of the lens stand 3, and the cam followers 208.
The tip end of 408 is guided in the optical axis direction of the optical system by cam grooves 302 and 304 formed in the cam cylinder 30 within the guide groove 14 of the cylinder body 10, and therefore the variator lens 202
．． 402 is moved in the optical axis direction, and the focal length of the lens as a whole can be changed.

On the other hand, the swing lever 7 swings in accordance with the amount of movement of the lens stand 3 and moves forward and backward to follow the movement of the lens stand 7.

In addition, if the optical axis of the variator lens 202, 402 is shifted from the original optical axis, the variator lens 202, 402 can be moved by rotating the eccentric pins 212, 412 provided on the holding frame 20, 40, respectively. Tilt it against the optical axis of the lens system, and insert the variator lens 202.402
The optical axis 31g and u can be set.

Now, a cam barrel with a cam groove of a predetermined shape is applied to a lens with a focal path ^U, but the focal length of lenses that are actually manufactured is slightly uneven, and the cam tube with a predetermined cam groove Even just one locus is inappropriate, and the conjugate length cannot be matched to the preset conjugate length of the copying machine, resulting in blurred images especially when changing the magnification. Therefore, even if the lens has a focal length different from a predetermined value, it is necessary to correct the focal length so as not to cause image blurring.

In Fig. 4, the position of the lens when the magnification is m is generally a,
= L/m4-1, then the lens focal length f, , = m L.

(m+1)2 Also, when the magnification is the same, the lens position is a+-L/2 and the focal length fl=L/4.

Amount of lens movement from the same magnification position α = a, , -a, = (1/
(mki1)-1/2) L, so the lens focal length fm for the lens movement amount α is the same as when the lens is at the same magnification. It turns out.

Inside the lens barrel 4, a lens group consisting of a convencator lens 12 and a Pariec lens 202, 204 is used.
02.204 is moved by rotating the cam cylinder 30 ffJJ.

On the other hand, as shown in FIG. 5, in the mechanism of the present invention, α-βXta
If the tooth ratio of the gear 30A on the outer circumference of the middle cam cylinder and the gear 7A on the lever tip socket is T, then the rotation angle θ of the cam cylinder 30 = γΦ-7ta
The cam cylinder 30 is rotated by n-'Xα/β.

The present invention attempts to slightly correct the rotation angle θ of the cam relative to the amount of lens movement so that clear imaging performance can always be obtained even when using a lens with a slight error from the predetermined focal length. .

Now, if we move the bracket 8 through the elongated hole 8a and set the pin 8A to a position slightly shifted by △β, then △θ/T△β=
△φ/△β−−α/(α2+β2)−(sinZΦ)/
The rotation of the cam cylinder 30 can be sub-adjusted slightly by Δθ with 2β,°, Δθ−r/2 X5in2φ×Δβ/β.

〔Effect of the invention〕

As explained above, according to the lens magnification changer according to the present invention, a gear is carved on the outer periphery of the cam cylinder that moves the movable lens,
Since the drive lever having the gear that meshes with this gear is configured to swing and move back and forth freely so as to follow the cam cylinder, the lens magnification changing mechanism can be formed in a thin shape.

Furthermore, according to the present invention, it is possible to adjust the rotation angle of the cam relative to the amount of lens movement, so lens errors can be adjusted and clear magnification performance can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the general structure of a copying machine, FIG. 2 is a perspective view showing essential parts of the present invention, FIG. 3 is an exploded perspective view showing a zoom lens barrel according to the present invention, and FIG. FIG. 5 is an explanatory diagram showing the change in magnification conversion and lens focal length, and FIG. 5 is an explanatory diagram showing the relationship between the amount of movement of the swing lever and the cam barrel. 1... Housing, 2A, 2B... Mirror, 3...
Lens stand, 4... Lens barrel, 5... Motor, 7... Swing lever, 7A... fL gear,
7B... Long hole, 8Δ... Pin, 30... Cam tube. Figure 2

Claims (1)

[Claims] In a lens magnification device that moves the entire optical system consisting of a lens group including a movable lens within a housing and moves the movable lens to change the lens interval of the lens group to change the magnification of the optical system. A cylinder with a linear guide groove formed in the optical axis direction, a cam cylinder with a cam groove formed in the circumferential direction and a gear carved on the outer periphery, and a radius of the lens holding frame that holds the movable lens. A cam follower that protrudes outward and fits into the guide groove of the cylinder body and the cam groove of the cam cylinder, and moves the lens holding frame in the optical axis direction as the cam cylinder rotates; In addition, the drive lever is supported so as to be able to move forward and backward, and a gear that engages with the gear of the cam barrel is formed at the end, and the drive lever rotates the cam barrel following the movement of the optical system, and the swinging fulcrum of the drive lever is movable. A lens magnification changer comprising: a drive lever support part that supports a drive lever.