JPS6227700B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mechanism for moving a zoom lens system in a copying machine that uses a zoom lens system to change magnification.

Regarding the variable magnification device of a copying machine using a zoom lens system, there is a variable magnification device that can change the magnification at any desired magnification ratio using a numerically controlled motor, which is disclosed in Japanese Patent Application No. 37841/1989 filed by the present applicant. However, when considering only the variable magnification device, the mechanical structure is simple, but the numerical control device is complex and expensive, and when considering the entire copying machine, for example, the photoreceptor rotates by mirror scanning. In order to enable arbitrary magnification in a copying machine that forms an image of a document on a drum,
It is necessary to continuously change the mirror scanning speed according to the magnification ratio for the photoconductor drum that rotates at a constant speed, so a numerically controlled motor or the like must be used as the drive motor for mirror scanning.
The control device is complicated and is not suitable for popular models.

The present invention was made with attention to these points, and the first purpose is to use a commonly used AC motor or DC motor, which is an inexpensive motor whose position cannot be regulated. The present invention provides a variable magnification device having two stages of variable magnification for two limited types of variable magnification.

A two-stage variable magnification mechanism of equal magnification and reduced magnification will be explained with a schematic diagram according to the drawings.

In order to use a zoom lens system to change the copying magnification without changing the distance between the object and the photosensitive surface, it is necessary to stop the entire zoom lens system from moving in the optical axis direction and move the zoom lens. The correlation between the multiple lens groups that make up the system must also be changed.

FIG. 1 relates to a zoom lens system consisting of two lens groups, and shows changes in the amount of movement in the optical axis direction and the correlation between each lens group depending on the magnification. Assuming that the positions of the first lens group b and the second lens group c at the same magnification of the zoom lens system a are A and B, when the original image is reduced to a constant magnification without changing the object-image distance, only a certain amount is reduced. The zoom lens system a is moved parallel to the optical axis toward the imaging plane, and the first lens group b and the second lens group c are also moved to C and D.
must be moved to this position.

Note that when positioning a document in a copying machine, it is easier to work and mechanically desirable if the document can be set by applying it in one direction, regardless of the size of the document or the copying magnification. For this purpose, the entire zoom lens system a must be moved in a direction perpendicular to the optical axis.

FIG. 2 will be explained. The position of the zoom lens system at equal magnification is assumed to be H, and the position of the zoom lens system at reduced magnification is assumed to be K. Zoom lens system a
If the edge A of the documents A and B is placed at the reference position by moving in parallel by an amount x corresponding to the magnification ratio m in the direction perpendicular to the optical axis, the image A' of the edge A will be The image is also formed at a fixed position. Therefore, the position of the edge of the copy paper can be set at a constant position with reference to A'. The amount of parallel movement x is determined by the following equation. The length between the optical axis O and the edge of the document at the same magnification is l/2,
If the reduction magnification is m, then (l/2-x):(l/2+x)=1:m, so x=m-1/m+1×l/2.

As described above, the zoom lens system a when changing the magnification is
A mechanism in which the first lens system b and the second lens system c move by a predetermined amount according to the magnification ratio in the optical axis direction, and a mechanism in which the entire zoom lens system a moves by an amount according to the magnification ratio in the direction perpendicular to the optical axis. A mechanism for parallel movement is required.

An embodiment of the present invention will be described below.

3 and 4 show a holding and guiding mechanism for the lens barrel.

The first lens barrel 2 to which the first lens group 1 is attached and the second lens barrel 4 to which the second lens group 3 is attached are slidably fitted so that their optical axes coincide, and The lens barrel 2 and the second lens barrel 4 constitute a zoom lens system.

The moving means in the optical axis direction arrow F is the first lens barrel 2
The outer periphery of the second lens barrel 4 is attached to the holding member 5, and the outer periphery of the second lens barrel 4 is attached to the holding member 6. A bridge portion 5a is formed at the lower end of the holding member 5, and a concave bridge portion 6a is formed at the lower end of the holding member 6. Midway parts of the bridge sections 5a and 6a are slidably fitted into guide rods 7 and 8 that are bridged between a mount 9 and a mount 10 attached to a moving plate 19 in parallel with the lens barrels 2 and 4. has been done. By sliding the holding members 5 and 6 on the guide rods 7 and 8, movement in the optical axis direction arrow F is effected.

The means for moving the arrow E in the direction perpendicular to the optical axis will be explained.
The lower end of the mount 9 is slidably fitted into a guide rod 11 which is bridged between the mounts 41 and 42 mounted on the base plate 20 at right angles to the lens barrels 2 and 4. The roller 16 is mounted so as to roll on the base plate 20. Note that a lead cam 20a is formed on the base plate 20, and a cam follower 18 is rotatably attached to the lower surface of the bridge portion 5a. Moving plate 19 and base plate 20
The cam follower 18 is pressed against the lead cam 20a by a tension coil spring 17 in between.
By moving the cam follower 18 on the lead cam 20a, the cam follower 18 moves in a direction perpendicular to the optical axis.

A normal AC or DC motor 21 is used as the drive source. The output shaft of the motor 21 is the coupling 2
2 is attached to the worm 23.

To explain these related parts in detail with reference to FIG. 5, the worm wheel shaft 24 is attached to the moving plate 19.
is fixed with a screw 36, and the worm wheel shaft 24
The wheel 25 is rotatably fitted therein. A lever 26 for operating micro switches 34 and 35 is fixed to the wheel 25 with a set screw 37. Drive pulley 27 is also set screw 3
8 to the wheel 25. A retaining ring 29 is attached to the upper end of the worm wheel shaft 24 to prevent the wheel 25 from slipping off. The wire 28 is wrapped around the drive pulley 27 several times. The central portion of the wound wire is wrapped about once around a screw 39 and fixed to the drive pulley 27 to prevent the wire 28 and the drive pulley 27 from slipping. The wires 28 are stretched in opposite directions and are connected to the bridge portion 5a via pulleys 30 and 31, and tension coil springs 32 and 33 shown in FIG.
It is applied from both directions to a spring hook 40 attached to the.

The moving state will be explained with reference to FIGS. 6 and 7. FIG. 6 shows the state when the magnification is set to the same magnification position, and FIG. 7 shows the state when the magnification is set to the reduced magnification position.

If we move from the equal magnification position to the reduced magnification position, the motor 2 electrically rotates forward and reverse.
1 and rotates the drive pulley 27 counterclockwise, the holding member 5 is moved to the right and the setting position C of the first lens group b and the second lens group c at the reduction magnification shown in FIG. - In order to maintain the distance D, the holding member 6 hits the stopper 13 which is adjustable and is moved to the right in the same way as the holding member 5, and the pedestal 9 is reduced in size as shown in FIG. In order to maintain the zoom lens system set position K during magnification, the holding member 6 hits the adjustable stopper 12, and the holding members 5 and 6 stop, but the motor 21 continues to rotate and the tension coil spring 33 After pulling the appropriate amount, the lever 26 operates the stop micro switch 35, and the motor 21
stops. After the motor stops, tension coil spring 3
The worm 23 and the worm wheel 25 rotate the drive pulley 27 clockwise due to the force of 3.
This is prevented by

By the above method, the tension coil spring 33 reliably presses the lens in the right direction, completing the movement in the optical axis direction to the reduction magnification.

The cam follower 18 is moved in the direction perpendicular to the optical axis in FIG. 2 by moving on the lead cam 20a from the cam follower position 18a at the same magnification to the cam follower position 18b at the reduced magnification as the holding member 5 moves. Complete amount x.

Motor 21 is used to move from reduced magnification to equal magnification.
Rotate the drive pulley 27 clockwise by
The stoppers 15 provided on the holding member 4 accurately hold the positions A and B of the first lens group b and the second lens group c at the same magnification as shown in FIG.
As shown in FIG. 2, the stopper 14 provided in the zoom lens system accurately holds the zoom lens system setting position H at the same magnification.

Since the stoppers 12, 13, 14, and 15 are adjustable, focus adjustment, magnification adjustment, etc. at each magnification can be easily performed, which has the advantage of increasing work efficiency.

In the present invention, the two-step magnification change for the same magnification and the reduction magnification has been described above, but the desired two-step magnification can be changed by changing each movement amount. In addition, since a normal motor is used, control is simple and inexpensive.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the amount of movement in the optical axis direction and the correlation between each lens group depending on the magnification in a zoom lens system consisting of two lens groups.
The figure shows the movement of the entire zoom lens system in a direction perpendicular to the optical axis, Figure 3 is a perspective view of a movement mechanism showing an embodiment of the present invention, and Figure 4 shows a holding and guiding mechanism for the zoom lens system. 5 is an exploded perspective view of the drive pulley, FIG. 6 is a plan view showing the drive pulley positioned at the same magnification position, and FIG. 7 is a plan view showing the drive pulley positioned at the reduced magnification position. . 1: first lens group, 2: second lens group, 5,
6: Holding member, 12, 13, 14, 15: Stopper, 18: Cam follower, 19: Moving plate, 20: Base plate, 21: Motor, 2
6: Lever, 27: Drive pulley, 28: Wire, 32, 33: Tension coil spring, 34, 3
5: Micro switch.

Claims (1)

[Scope of Claims] 1. A zoom lens system consisting of at least two lens groups is used as an optical system, a drive motor whose position cannot be regulated by itself is used as a drive source, and the zoom lens system is moved in the optical axis direction and along the optical axis. In a two-stage magnification device for a copying machine, the drive motor is moved in a direction perpendicular to the optical axis direction and the drive motor is stopped at two predetermined magnification positions in the composite movement direction, a base plate formed with intersecting lead cams, one end of which is movably guided by a guide rod in a direction perpendicular to the optical axis direction on the base plate, and a roller that rolls on the base plate is attached to the other end; A movable plate biased by a spring in a direction intersecting the lead cam, and two guide rods bridged on the movable plate in the optical axis direction are movably guided, and one lens barrel is connected to the other lens. two lens barrels that are slidably fitted into each other and are provided with means for regulating an adjustable relative movement range of the lens barrels; a cam follower that engages with the lead cam through a perforated window; and a drive that is provided on the movable plate, and the rotation of the drive motor that is also provided on the movable plate is transmitted via a worm gear and a worm wheel. a pulley, and two pulleys that are wound around and fixed around this drive pulley, and whose ends are provided at positions on the movable plate that are spaced apart from each other by a predetermined distance along the two guide rods, and are driven by a spring. A wire attached to a lens barrel whose movement range is regulated; A lever attached to the drive pulley so as to rotate coaxially with the drive pulley; two microswitches that are actuated by the respective levers at corresponding rotational positions and used to control the stoppage of the drive motor; A two-stage variable magnification device for a copying machine, comprising: an adjustable stopper for regulating the two variable magnification positions of the two lens barrels.