JPH0240639A - Variable power optical device for copying machine - Google Patents

Abstract

PURPOSE:To surely achieve movement of a mirror even when a moving amount is large by supporting an operation lever so as to rock, equipping a cam follower on one end, connecting it with a mirror retaining member on the other end, and arranging it so as to move the mirror retaining member following a cam member. CONSTITUTION:Relation between the shape of the cam groove 4A of a cam plate 4 and the position of the supporting point of a lever 7 is set so that displacement from the rotation center of the cam groove 4A is maximum when magnification ratio is set for that of unmagnification. In addition, the cam groove 4A is set so as to approach the rotation center when the lever is moved to an enlarging side or a reducing side. As a result, a mirror holder 2 is moved by a large amount for the rotation angle of the cam plate 4 especially when the lever is moved from an unmagnified position to the enlarging side. Even when additional force is required, an identical torque can be used as a strong driving force for movement, because the cam groove 4A approaches the rotation center.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a variable magnification optical device used in copying machines and the like that changes the magnification by moving a fixed focal length lens.
More specifically, the present invention relates to an improvement in a mechanism for moving and driving a mirror interposed between a lens and a projection surface in synchronization with the movement of the lens.

(Prior Art) Conventionally, a so-called electronic copying machine that performs copying using electrophotography illuminates a document placed on document aW1 with a light source such as a fluorescent lamp, and also illuminates the document illuminated by the light source. It is configured to form an image of the surface onto the photosensitive drum by an imaging optical system composed of a lens and a mirror.

Recently, the magnification rate of the projected image has been improved by moving the lens constituting the imaging optical system in the optical axis direction and changing the distance from the document surface to the lens and the distance from the lens to the projection surface (i.e., the surface of the photosensitive drum). There is a variable magnification optical device configured to make the image variable, and has a so-called variable magnification function that allows copying to be made from the same size as the original (same size) by enlarging or reducing it.

In such a variable magnification optical device that uses a fixed focal length lens (a lens with a constant focal length), the first
As shown in Figure 0, a mirror part C, which has two mirrors arranged facing each other with an angle of 90 degrees between them, is interposed between the lens A and the photosensitive drum B, and the optical path is reversed by this mirror part C. At the same time, this is moved (
Y) in the figure, and is configured to form an image on the surface of the photosensitive drum 6.

The lenses and mirrors are configured and movable as shown in Figure 11.

That is, the lens 1 is installed such that the lens holding member IA that holds the lens 1 is slidably fitted into the guide member 11 provided on the chassis of the device, and the mirror is installed so that the mirror holding member 2 that holds the mirror is fitted on the chassis. The guide member 13 is installed so as to be slidably fitted in the guide member 13 provided in the guide member 13 provided therein. A pulley 3 that is rotationally driven by a motor (not shown) is wound around the lens holding member IA, and a J! The predetermined position of the endless wire 6 is fixed, and the lens holding member IA is moved and driven by the endless wire 6 which is rotated by the rotation of the motor.

Since the movement of the mirror holding member 2 needs to be moved in a predetermined relationship with the movement of the lens 1 as described above, the pulley 3 that drives the lens l (lens holding member IA) to move
The cam follower 25 provided on the mirror holding member 2 follows the cam 4 which is rotationally driven in synchronization with the rotation of the mirror holding member 2.

(Problems with the Prior Art) However, although there is no problem when the magnification of the projected image is within a relatively narrow range of 1.4x to 0.6x, for example, when the magnification is 2.05x to 0.48x, If you try to widen the magnification range, the amount of mirror movement will naturally increase,
Therefore, as the amount of displacement of the cam increases, the conventional configuration described above has a problem in that the cam follower is unable to follow the cam and the mirror cannot be moved.

In order to solve this problem, the lens and mirror are configured to be moved and driven by separate motors, respectively.
There are some configurations that drive both in synchrony, but
This would increase manufacturing costs.

(Object of the Invention) In view of the above-mentioned circumstances, the present invention provides a variable magnification copying machine that can accurately move and drive even when the magnification range is wide and the amount of mirror movement is large, and can be manufactured at low cost. The purpose is to provide optical devices.

(Means for Solving the Problems) For this purpose, a variable magnification optical device for a copying machine according to the present invention includes a cam member that can be rotated, a cam follower that is pivotably supported on a fixed member at one end, and a cam follower at one end. an operating lever whose end is connected to a mirror holding member that holds the mirror;
The cam follower follows the cam member to swing the operating lever and drive the mirror holding member to move.

Furthermore, the cam member that can be driven one rotation and the arm member that has a cam follower at one end and rotatably supports the free pulley are configured so that the cam follower follows the cam member and the arm member moves, and the one end is fixed. A wire that is fixed to a member and whose other end is connected to a mirror holding member that holds a mirror is connected to a free pulley, so that movement of the arm member causes the mirror holding member to move via the wire.

Furthermore, a free pulley is rotatably provided at the other end of the operating lever, and a wire is connected to the free pulley, one end of which is fixed to a fixed member and the other end of which is connected to a mirror holding member that holds a mirror. The mirror support member may be configured to move via a wire by swinging.

Further, the cam member may be integrally formed with a gear portion for transmitting rotational force to the cam member and a pulley around which an endless wire fixed to a moving lens is wound and drives the endless wire to rotate. .

(Embodiment of the Invention) An embodiment of the present invention will be described below based on one drawing. 6 FIG. 1 is a plan view of a variable magnification optical device of a copying machine according to the present invention;
FIG. 2 is a longitudinal sectional view thereof. The variable power optical device has a variable power range of 2.05 times to 0.48 times.

In the figure, ■ is a lens, 2 is a mirror holder as a mirror holding member that holds the mirror 21, and 4 is a cam plate as a cam member.

Lens l is held on lens holder IA. A bearing part IB is formed at one end of the lens holder IA, and a lens guide shaft 11 installed in the chassis 10 with its longitudinal direction aligned with the optical axis direction of the lens 1 is formed in the bearing part IB. They are slidably fitted, and the lens holder IA (namely, the lens 1) is movable along the lens guide shaft 11 (namely, in the optical axis direction of the lens 1).

Mirrors 21 are arranged in the mirror holder 2 in a predetermined positional relationship. As shown in FIG. 2 and FIG. 3, which is the opposite side of the mirror holding part, an opening 22 through which the mirror 21 passes is formed in both side walls of the mirror holder 2, and the mirror 21 is formed at the periphery of the opening 22. A supporting protrusion 22A is formed protrudingly on the side corresponding to the surface (reflecting surface), and an elastically deformable suppressing holding protrusion 22B is integrally formed on the periphery opposite to this in correspondence with the supporting protrusion 22A. The mirror 21 is held in the mirror holder 2 by pressing the mirror 21 against the support protrusion 22A using the elastic return force generated by the deformation of the holding protrusion 22B. In addition, the support protrusion 22
As shown in Figure 1, the mirror 21 is held in two places on one end side and one place on the other end, so that the mirror 21 is supported stably by three points. It is something that

A bearing part 2A is integrally formed at one end of the mirror holder 2, and a mirror guide shirt 13 installed on the chassis 10 parallel to the moving direction of the lens l can freely slide on the bearing part 2A. The lens 1 is fitted into the mirror guide shaft 13 and is movable in a direction parallel to the moving direction of the lens 1.

Here, the lens guide shaft 11 and the mirror guide shaft 13 are installed parallel to the chassis lO,
At the bent upright portion 10A at the end of the chassis 10, a fourth
As shown in the figure, they are fixed simultaneously by one clip 14.

The clip 14 is made by bending an elastic wire such as a piano wire, and has an engaging portion 14A that is wider than the spacing between the lens guide shaft 11 and the mirror guide shaft 13 in a free state.
Hooks 14B for hooking onto the chassis 10 are formed at both ends. Then, the hooks 1 at both ends are inserted into the opening 10B formed in the bent upright portion 10A of the chassis IO.
4B, deforms the engaging portion 14A, and engages with the respective engaging grooves 11A and 13A formed in both the guide shafts 11-13 with its natural return force, and both the guide shafts 1
1 and 13 are fixed so that they do not need to be moved. Note that the retaining portion 14A of the clip 14 is not parallel to the locking portion 14.
It has a shape that expands on the opposite side from B, and the engaging portion 14A
The elastic restoring force caused by the engagement with both guide shafts 11φ13 acts to ensure the locking to the bent upright portion 10A.

The cam plate 4 has a disk shape as shown in FIG. is formed. That is, the cam groove 4A, the boob portion 4B, and the outer peripheral gear portion 4C are integrally formed.

The motor 5, which is a flange-type pulse motor fixed to the back side of the chassis 10, protrudes from the outer peripheral gear portion 4C of the motor 5, which is rotatably installed at a predetermined position of the chassis 10 by a shaft 41. A gear fitted and fixed to the spindle meshes with the spindle, and is rotated by the motor 5.

A pulley 1 rotatably provided at both ends of the lens l of the chassis 10 in the optical axis direction is attached to the boom portion 4B of the cam plate 4.
Connect the 2φ12 and attach the lens holder IA at the specified position.
An endless wire 6 fixed to is wound once, and when the cam plate 4 rotates, the endless wire 6 is rotated and the lens holder IA is driven to move.

In addition, Fig. 1 shows a state where the magnification ratio is equal to the same magnification, and when enlarging, from this state, the lens boulder IA (lens L)
is moved in the direction of arrow X, and in the opposite direction during reduction.

A cam follower 71 fixed to one end of the lever 7 is slidably fitted into the cam 1A4A of the cam plate 4.

The lever 7 is integrally formed of a sheet metal in an L-shape with two long and short arms 7A and 7B orthogonal to each other, and is attached to the chassis 10 at the intersection of the two arms 7A and 7B. It is pivotably supported by a pin 72.

A cam follower 71 that slidably fits into the cam groove 4A of the cam plate 4 is fixed to the tip of the shorter arm 7A.

A long hole 73 is opened at the tip of the longer arm 7B in a direction along the longitudinal direction of the arm 7B.
A shaft 23 slidably passes through the mirror holder 2, and the bearing of the mirror holder 2 is fitted into and fixed to the portion 2A.

Then, when the cam plate 4 rotates and the cam follower 71 moves following the cam I11!4A, the lever 7 swings around its pivot point (bin 72), and the arm 7
The mirror holder 2 is moved and driven via the shaft 23 that fits into the elongated hole 73 at the tip of B. That is, the rotation of the cam plate 4 drives the mirror holder 2 to move.

Here, the amount of movement of the mirror holder 2 with respect to the amount of displacement of the cam groove 4A from the rotation center (shaft 41) is determined by the distance gl of the lever 7 from the pivot point to the cam follower 71 (that is, the length of the arm 7A), and the pivot point of the lever 7. It is enlarged according to the ratio of the shafting distance gl from the fulcrum (that is, the length of the arm 7B). That is, even if the amount of displacement of the cam groove 4A is small, the amount of movement of the mirror holder 2 can be increased. The movement of the mirror holder 2 with respect to the amount of displacement of the cam groove 4A! Tadashi is
It can be set arbitrarily by changing the length ratio (lever ratio) of the arms 7A and 7B.

In this embodiment, the ratio of the length of the arm 7A to the length S of the arm 7B is approximately 1:2. Further, the relationship between the amount of movement of the lens l and the mirror holder 2 with respect to the magnification ratio is as shown in FIG. In this case, the mirror holder 2 is set to move by the amount shown in the figure when the lens l is moved by the rotation of the cam plate 4. Therefore, no matter which direction you move from the state where the magnification ratio in Figure 1 is equal to the same magnification,
The mirror holder 2 moves in the direction away from the lens l (the rate of movement is different).In Figure 1, the vertical axis represents the magnification rate, and the horizontal axis represents the amount of movement, and the solid line in Figure 1 represents the lens. 1
, broken lines indicate the mirror 21 (mirror holder 2), respectively.

The relationship between the shape of the cam n4A of the cam plate 4 and the pivot point position of the lever 7 is such that when the magnification is equal to 1:1, the displacement of the cam groove 4A from the center of rotation is the largest, as shown in FIG. 6(A). Therefore, from 1st magnification to Fig. 6 (
The cam groove 4A moves closer to the rotation center (the amount of displacement from the rotation center becomes smaller) when moving to either the enlarged side shown in B) or the reduced side shown in FIG. , 4A' in FIG. 6 indicates the locus of the cam follower 71 along which the cam groove 4A also follows.

As a result, especially when moving from normal to enlarged (6th
Figure (B)) The amount of movement of the mirror holder 2 with respect to the rotation angle of the cam plate 4 is large (the contact angle of the cam follower 71 with respect to the cam groove 4A: θ is large), so a force is required to move the mirror holder 2. At this time, cam groove 4A
is closer to the center of rotation (the radius of rotation becomes smaller), so even if the torque for rotating the cam plate 4 is the same, a stronger moving driving force can be obtained, and a lower output motor 5 can be used. Furthermore, the fact that the amount of movement of the mirror holder 2 with respect to the rotation angle of the cam plate 4 is large means that accurate movement cannot be achieved unless the cam groove 4 is made highly accurate. However, in the case of this optical system, since the depth of focus becomes deeper toward the magnification side, the permissible accuracy becomes wider, so there is no need for particularly high accuracy.

In the direction where the magnification rate decreases (reduction side: Fig. 6 (C)),
Since the depth of focus becomes shallow, the cam groove must be highly accurate, but the amount of movement of the mirror holder 2 with respect to the rotation angle of the cam plate 4 is small (the contact angle 20 of the cam follower 71 with respect to the cam groove 4A is small). Groove 4A
Since the permissible accuracy becomes wider and the two cancel each other out, it is not necessary to make the accuracy particularly high.

That is, the cam groove 4A is configured to have approximately the same accuracy in both directions of enlargement and reduction across the same magnification, and can be driven more powerfully in directions that require force for movement.

Note that 8 in FIG. 1 is a shading correction plate, and as shown in FIG. An operating portion 8B is formed, and a shaft portion 8C protruding in any direction from the intersection of the shading portion 8A and the operating portion 8B is rotatably fitted into the chassis IO. This is to correct the inherent characteristic of the lens that the amount of peripheral light increases when the magnification is less than 1x, and the lens! When the lens holder IA (that is, the lens holder IA) moves from the same magnification to the reduction side, the operation part 8B is rotated by being kicked by the lens holder IA, and the shading part 8A stands up and blocks the optical path with a predetermined shape to correct the light amount. In addition, when the magnification is equal to or greater than the same magnification that does not require correction, the shading portion 8A is kicked and falls down by the moving lens holder IA. Furthermore, a light-shielding film 9 of a predetermined width is attached to the end surface of the lens l (lens holder LA) on the mirror holder 2 side to prevent light leakage, and the light-shielding film 9 changes as the lens holder IA moves. The shading correction plate 8A is moved to be located above the shading portion 8A in a state in which the shading portion 8A is fallen down, thereby making it possible to prevent the shading correction plate 8 from malfunctioning (rotation).

Next, a second embodiment of the present invention shown in FIG. 9 will be described.

This is because an outer peripheral cam 4D is formed in the cam plate 4 instead of the cam groove 4A.

The lever ratio of the lever 7 is l, and a cam follower 74. A pulley 75 as a free pulley is rotatably attached to the other end. Then connect one end to the chassis 10
The wire 15 fixed to the mirror holder 2 is connected to the pulley 75 and reversed, and the other end is fixed to the mirror holder 2.

Further, the mirror holder 2 is pulled and biased by a tension spring 16 whose one end is fixed to the chassis 10 in a direction opposite to the installation position of the cam plate 4 and 8-7.

With the above configuration, the shield 8-7 is pulled by the tension spring 16 via the mirror holder 2, the wire 15, and the pulley 74, so that the cam follower 74 comes into contact with the cam surface of the outer cam 4D.

Therefore, when the cam plate 4 rotates in the above configuration,
The lever 7 swings in accordance with the displacement of the cam surface of the outer cam 4D, and the swing of the lever 7 moves the pulley 75. When the pulley 75 moves, the mirror holder 2 to which one end of the wire 15 is fixed also moves.
5 moves! The amount of movement of the mirror holder 2 relative to the amount of tI is approximately double.

(If the connecting direction of the wire 15 is parallel to the moving direction of the mirror holder 2 and the pulley 75 moves in the same direction, the moving amount of the mirror holder 2 is accurate to the moving amount of the pulley 75. ) Therefore, the mirror holder 2 can be moved approximately twice as much as the amount of displacement of the cam surface of the outer cam 4D.

In this configuration, by changing the lever ratio of the lever 7, it is possible to appropriately change the amount of movement of the mirror holder 2 with respect to the amount of displacement of the cam surface of the outer cam 4D. By setting the amount of displacement of the surface, it is possible to set an arbitrary amount of movement.

Note that the member on which the pulley 74 and the cam follower 74 are arranged and moves does not necessarily have to be a swinging lever, and may be a member that can move linearly in the same direction as the moving direction of the mirror holder 2. .

(Effects of the Invention) According to the variable magnification optical device for a copying machine according to the present invention, even when the variable magnification ratio is large and therefore the amount of movement of the mirror is large, reliable movement can be achieved by one driving means.

That is, it is possible to reliably operate a wide range of magnification ratios with one driving means, and therefore it can be constructed at low cost.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of a variable magnification optical device for a copying machine according to the present invention, FIG. 2 is a longitudinal sectional view thereof, FIG. 3 is a view showing a mirror holding mechanism, and FIG. 4 (A). (B) is a diagram showing the fixing structure of the guide shaft, Figure 5 is a perspective view of the cam plate, Figure 6 is a diagram showing the cam groove shape of the cam plate and the swinging relationship of the lever, and (A) is the same size. ,
(B) shows the enlargement side, (C) shows the reduction side, FIG. 7 is a graph showing the relationship between the amount of movement of the lens l and the mirror holder 2 with respect to the magnification ratio, and FIG. 8 is a perspective view of the shading correction plate. FIG. 9 is a plan view of the second embodiment, FIG. 10 is an explanatory view showing the variable magnification mechanism, and FIG. 11 is a plan view of the conventional example. 1... Lens 2... Mirror holder (mirror holding member) 21... Mirror 4... Cam plate (cam member) 4A... Cam groove 4B... Pulley part (pulley) 4C... Outer gear part (gear part) 7...Lever (operation lever) (arm member) 71.7
4... Cam follower 75... Pulley (free pulley) 10... Chassis (fixed member) 15... Wire diagram + 4B Figure 8B Figure

Claims (4)

[Claims] (1) By moving the lens and the mirror interposed between the lens and the projection surface in the optical axis direction to change the distance from the document surface to the lens and the distance from the lens to the projection surface. A variable magnification optical device for a copying machine that makes the magnification ratio of a projected image variable, comprising a cam member that can be rotated, a cam follower that is swingably supported on a fixed member, and a cam follower at one end, and the other end that supports the mirror. An operating lever connected to a mirror holding member to be held, and the operating lever swinging as the cam follower follows the cam member to move and drive the mirror holding member. Variable magnification optical device for copying machines. (2) By moving the lens and the mirror interposed between the lens and the projection surface in the optical axis direction to change the distance from the document surface to the lens and from the lens to the projection surface. A variable magnification optical device for a copying machine that makes the magnification of a projected image variable, the cam member being rotatably driven, and an arm member having a cam follower at one end and rotatably supporting a free pulley. The arm member is configured to move following the cam member, and a wire having one end fixed to a fixed member and the other end linked to a mirror holding member that holds the mirror is linked to the free pulley, and the arm member is connected to the free pulley. A variable magnification optical device for a copying machine, characterized in that the mirror holding member is moved via the wire as the member moves. (3) By moving the lens and the mirror interposed between the lens and the projection surface in the optical axis direction to change the distance from the document surface to the lens and the distance from the lens to the projection surface. A variable magnification optical device for a copying machine that makes the magnification of a projected image variable, and includes a cam member that can be rotated, a cam follower that is pivotably supported on a holding member, and a cam follower at one end, and a free pulley at the other end. an operating lever rotatably supported; and a mirror configured such that the operating lever swings when the cam follower follows the cam member, and has one end fixed to a fixed member and the other end holding the mirror. A variable magnification optical device for a copying machine, characterized in that a wire fixed to a holding member is connected to the free pulley, and the mirror holding member is moved via the wire when the operating lever member swings. . (4) The cam member is integrally formed with a gear portion for transmitting rotational force to the cam member and a pulley around which an endless wire fixed to a moving lens is wound and drives the same; A variable magnification optical device for a copying machine according to claim (1), (2) or (3), characterized in that: