JPS6289032A - Lens moving mechanism for copying machine - Google Patents

Abstract

PURPOSE:To maintain directivity of the optical axis of a lens moved when varying power exactly and to make compact lens holding possible by connecting a lens frame bendably to a guide with a rigid link. CONSTITUTION:A guide 21 to which a lens frame 24 is connected through a rigid link 22 to make the optical axis 34 of a lens 10 incorporated in a lens frame 24 conform to the optical axis of the optical system of a copying machine is fixed to a base stand 27. A cam 26 is fixed to the base stand 27 to make a cam follower 25 attached to a part of outer periphery of the frame 24 to make the frame to generate a specified locus according to magnification of copying rotate in contact with the cam face 33 of the cam 26. The optic axis 34 of the lens 10 is set initially to form a specified angle theta with the guide 21. As the guide 21 is fixed to the base stand 27, the angle theta is kept fixed even when the frame 24 is moving and directivity of the optic axis 34 is maintained surely to one direction. Thus, the directivity of the optical axis moved when the power is varied can be maintained accurately, and the compact lens holding becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mechanism for moving an imaging lens in a copying machine in accordance with the copying magnification.

(Prior Art) In a copying machine that allows the copying magnification to be changed, an imaging lens is provided between the document and the recording surface of a photosensitive drum, etc.
The imaging lens is held in a lens frame that is movable in the optical axis direction, and the lens frame is moved to a position according to the copying magnification. At the same time, the conjugate length is corrected as the copying magnification changes by moving an optical path conversion mirror disposed coaxially with the imaging lens.

By the way, in the method of copying by aligning the center of the original with the center of the original R placing table (center registration method),
The imaging lens, whether a fixed focus lens or a zoom lens, moves straight along the optical axis passing through the center of the copying optical system. on the other hand,
Even in the method of copying by aligning one end of the original to a predetermined position on the document table (corner registration method), if a zoom lens is used that changes the focal length as the imaging lens moves, the imaging lens will align with the lens optical axis. Move in a straight line in a direction diagonal to . However, in the corner registration type copying system, in a copying optical system using an imaging lens with a fixed focal length, the imaging lens is, in principle, moved along a predetermined curve according to the copy/credit ratio. There must be.

Therefore, as a method for moving the imaging lens in a curve, as shown in FIG. Japanese Patent Publication No. 6O-1 by the applicant
2537) is known.

(Problems to be Solved by the Invention) However, when the lens frame is moved using the method described above, two sets of linear guides are required in the X direction and the Y direction, and the linear guides are driven by wires. for,
The volume of the device was increased.

The present invention was made in order to eliminate the drawbacks of the prior art described above, and it is possible to accurately maintain the directionality of the lens optical axis of the lens that is moved when changing the magnification, and also to enable compact lens holding and movement. The purpose is to provide a mechanism.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a linear guide and a curved cam, each fixed to the base of a copying device,
A link mechanism connects the lens frame and the linear guide that maintains a predetermined angle with respect to the lens frame, so that the linear guide maintains the directionality of the lens optical axis of the moving lens.

A spring is provided in the link mechanism, and the spring force causes a cam follower of the lens frame provided in a direction opposite to the linear guide to always come into pressure contact with the cam,
The lens moves in a curve along the cam surface.

According to a preferred embodiment of the present invention, the link mechanism is configured to freely slide on the guide by a wire, belt, or the like rotated by a pulley.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the attached drawings.

(Embodiment) The optical system shown in FIG. 4 is an optical system suitable for employing an embodiment of the lens moving mechanism in a copying machine of the present invention. In Fig. 4, a document placement surface 1 made of a glass plate, etc.
When the original 2 is placed with the original surface facing down and the original placing surface 1 is moved in the direction of arrow 3, the image of the original illuminated by the light source 4 is scanned as a line-shaped image through the slit 5. be done. This line-shaped image is formed by the mirror 6.
7.8, imaging lens 10, mirror 1). The image is formed on the photosensitive drum 14 via 12 and 13. Since the photosensitive drum 14 rotates around the shaft 15 while maintaining a constant relationship with the movement of the document placement surface 1, an image of the entire surface of the document 2 can be recorded on the photosensitive drum 14.

The imaging lens 10 is composed of a lens with a fixed focus, and the copying magnification can be changed by moving the imaging lens lO to the optical axis 1.
6 in the direction of arrow 19 or 20.

Then, as the copying magnification changes, the original 2 is changed to the photosensitive drum 1.
The optical path length can be corrected by moving the mirror system 17 consisting of the mirrors 1) and 12 back and forth in the direction of the arrow 18.

FIG. 1 shows an embodiment of the present invention, showing an imaging lens 10 and a mechanism for holding and moving the imaging lens 10. The base 27 is a rigid body whose upper surface has a plane parallel to the optical axis of the optical system, and is generally made of an aluminum plate, a steel plate, or a plastic molded product. The main components of the present invention are the base 27
To attach the lens to the lens frame 24, first attach it to the lens frame 24 via the link 22 so that the lens optical axis 34 of the lens 10 incorporated in the lens frame 24 coincides with the optical axis 16 of the copying machine optical system shown in FIG. The guide 21 connected to the base 27
sticks to. Next, the lens frame? 4 draws a predetermined trajectory according to the copying magnification (so that the cam follower 25 attached to a part of the outer periphery of the lens frame 24
The cam 26 is fixed to the base 27 so as to contact the cam 3 and rotate.

The cam 26 is made of a rigid body such as aluminum, steel, or plastic, and has a mechanical contact width sufficient for the cam follower 25 to contact and rotate, and a mechanism that satisfies the range of variation in copying magnification. It is made up of length.

The lens frame 24 and the base 2 are arranged on the outer periphery of the lens frame 24.
Guide 2 fixed to 7 by brackets 60 and 61
A link 22 is provided to connect the two.

The link 22 has link arms 22a and 22 having the same length.
b, and have a shape that intersects each other with the pin 41 at the center. The link arms 22a and 22b are connected to the cam 26.
It is made of a rigid body equivalent to . One end of the link arm 22a is rotatably attached to the lens frame 24 with a pin 43.

One end of the link arm 22b is rotatably attached to a bearing 29c with a pin 42. The bearing 29c is attached to the lens frame 24
It is inserted through a shaft 23 attached to the shaft 23 so that it can slide on the shaft 23.

The other ends of the link arms 22a and 22b are attached to slide bearings 29b and 29a, respectively, which are inserted through the guide 21, using pins 44 and 45, respectively. The slide bearings 29a and 29b are connected by a spring 28.

The bearings 29a and 29b can slide on the guide 21. The guide 21 is made of a rigid body similar to the cam 26, and is made of straight drawn material having nine, rectangular, or irregular cross-sectional shapes.

One end 23a of the shaft 23 and the end 241 of the lens frame 24, which is on an extension of the shaft 23, are connected by a wire 32, and this wire forms a loop, which is hung on a pulley (not shown) so that it can rotate. .

Here, the effect of the above configuration will be explained.

When the pulley is rotated in the direction in which the copying magnification changes, the wire 32 is pulled in the direction of arrow 35. Bearings 29a and 29b, to which the force is transmitted by the spring 28, are connected to the guide 2.
1, and the link 22 brings the cam follower 25 attached to the lens frame 24 into pressure contact with the cam surface 33. The link 22 expands and contracts its intersecting shape by the biasing force of the spring 28 to keep the cam follower 25 in constant contact with the cam surface 33, and the cam follower 25 contacts the curved cam surface 33 and smoothly rotates while rolling. do.

At this time, the optical axis 34 of the lens 10 is initially set to form a predetermined angle (θ) with the guide 21.
1 is fixed to the base 27, the angle (θ) is always maintained constant even while the lens frame 24 is moving, and the directionality of the lens optical axis 34 is reliably maintained in one direction. A flange 33a is provided above the cam surface 33 to suppress the cam follower 25 from floating and to prevent the lens frame 24 from floating.
Since the other end is regulated by the guide 21, the lens frame 24 and the link 22 do not move in the vertical direction of the base 27 while the lens frame 24 is moving.

FIG. 2 shows another embodiment in which the common pin 46 is located at the outer dividing point of the link arms 22c and 22d.

In FIG. 2, the link arms 22C and 22d are connected to the first
Corresponds to link arms 22a and 22b in the figure, pin 49
and 50 correspond to pins 42 and 43 in FIG. The link arms 22C and 22d are rotatably attached to bearings 94 and 93 inserted through the guide 21a by pins 48 and 47, respectively. Bearings 93 and 94 are spring 2
8a, and can slide on the shaft 2Ia. The shaft 70 is rotatably attached to the link arms 22c and 22d with pins 49 and 50, respectively. The support member 91 of the lens frame 24 has a pin 90 on the shaft 70.
The lens support member 92 is rotatably attached to the shaft 7.
0 so that it can slide on the shaft 70. The cam surface 33b of the cam 26a has a curved shape, and the cam follower 25a of the lens frame 24 is in contact with the cam surface 33b. Here, the effect of the above configuration will be explained. When the wire is pulled in the direction that changes the copy magnification, you will hear a huff! , 28 acts on the pin 46 and the shaft 70 to move them away from the guy F21a. Accordingly, the cam follower 25a of the lens frame 24 is pressed against the cam surface 33b of the cam 26a and rotates smoothly along the cam surface 33b. And guide 21a, link arm 22C
The triangle formed by the link arm 22d and the link arm 22d is
Since the shape is similar to the triangle formed by the shaft 70, the link arm 22c, and the link arm 22d, the guide 21a and the shaft 70 become parallel to each other, and even if the lens frame 24 moves, the lens optical axis 34a and the shaft 21a The angle formed by the optical axis 34a is always kept constant at the initially set angle, and the directionality of the optical axis 34a is maintained in one direction.

FIG. 3 shows yet another embodiment in which the common bin corresponding to pin 41 of FIG. 1 and pin 46 of FIG. 2 is at the infinity position. The sliding member 80 has a U-shape, and the guide 21
b so that it can slide on the guide 21b. The end of the link arm 55 is attached to the lens frame 24.
It is rotatably attached to the lens support member 96 and sliding member 80 with pins 52 and 51, respectively. The end of the link arm 56 is attached to the lens support member 9 of the lens frame 24.
5 and sliding member 80 with pins 53 and 54, respectively. Spring 28b is attached with pins 52 and 54.

Wire 97 is attached with pins 52 and 53.

Link arm 55, 56, sliding member 80 and wire 97
form a parallelogram. The cam follower 25b of the lens frame 24 is in contact with the cam surface 33c of the cam 26b. Here, the effect of the above configuration will be explained. When the wire is pulled in the direction that changes the copy magnification, the spring 28
Due to the biasing force b, a force is applied to move the lens frame 24 away from the guide 21b, and the cam follower 25b is moved away from the cam 26.
b is pressed against the cam surface 33c and rotates along the cam surface 33c. Due to the above parallelogram mechanism, the lens optical axis 3
4b and the guide 21b is always maintained at the initially set angle even while the lens frame 24 is moving, and the directionality of the lens optical axis 34b is reliably maintained in one direction.

Note that the cam 26a in FIG. 2 and the cam 26b in FIG.
A flange corresponding to the flange 33a of the cam 26 in FIG. 1 is omitted.

(Effects of the Invention) As explained above, according to the lens moving mechanism of a copying machine using the present invention, the lens frame in which the lens is incorporated can
Since it is bendably connected to the guide with a rigid link, there is no wobbling of the lens optical axis even when the lens moves due to changes in copying magnification, and the directionality of the lens optical axis is reliably maintained in one direction. Not only that, but the lens frame can move along a predetermined trajectory along the shape of the cam.

Furthermore, since all the members constituting the lens moving mechanism can be arranged in a plane without stacking them three-dimensionally, the structure is simple and the mechanism can be made thin and compact.

Furthermore, since the lens frame is slid along a guide fixed to the base via the link, driving is reliable and the amount of feed of the lens frame can be easily defined. It goes without saying that this lens moving mechanism can be used not only for copying machines but also for enlargers and projectors that can change the imaging magnification of the optical system.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention. FIGS. 2 and 3 are plan views showing other embodiments of the present invention. FIG. 4 is a schematic diagram showing an optical system of a copying machine using the present invention. FIG. 5 is a plan view showing a conventional example (Japanese Patent Laid-Open No. 6O-12537). 21.21a, 21b...Guide 22...Link 24...Lens frame 25.25a, 25b-Cam follower 26.26a, 26b...Cam 27...Base 28.28a, 28...Spring 32...Wire 34...Lens optical axis 41-54...Pin

Claims (1)

[Claims] (1) In a copying machine in which the copy magnification is changed by moving a lens frame holding an imaging lens in the optical axis direction, the lens frame and the lens optical axis of this lens frame are maintained at a predetermined angle. a link mechanism disposed between the lens frame and the linear guide member so that the lens optical axis maintains a predetermined angle with the linear guide member when the lens frame is moved; A lens moving mechanism for a copying machine, comprising: cam means that engages with the lens frame and controls the lens frame to move in a predetermined curve.