JPS5817463A - 2 stage variable magnification device of copying machine - Google Patents

Abstract

PURPOSE:To obtain a device having a 2 stage variable magnification, which is used frequently, by using an inexpensive motor whose position cannot be controlled, such as an AC motor or a DC motor. CONSTITUTION:The first lens barrel 2 to which the first lens group 1 has been installed, and the second lens barrel 4 to which the second lens groups 3 has been installed are fitted into each other so as to be freely slidable, and constitute a zoom lens system. By a moving means indicated with an arrow F in the optical axis direction, the outside circumference of the lens barrel 2 is installed to a holding member 5, and the outside circumference of the lens barrel 4 is installed to a holding member 6. A middle part of bridge parts 5a, 6a is fitted so as to be freely slidable, to guide rods 7, 8 bridged in parallel with the lens barrels 2, 4 between a rack 9 and a rack 10 intalled to a moving plate 19. Along these guide rods 7, 8, the holding members 5, 6 slide. Desired 2 stage variable magnification can be exectued by changing each moving extent, and also since a regular motor is used, the control is executed easily.

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.

In 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. 55-37841 filed by the present applicant. However, when considering only the variable magnification device,
1. Although the basic structure is simple, several KIIL control devices are a
Considering the entire copying machine, for example, in a copying machine where a mirror is placed on a rotating photoreceptor drum, K is used to enable arbitrary magnification. In this case, 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. Therefore, it is necessary to use a spring numerically controlled motor etc. as the drive motor for mirror scanning. Moreover, 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 commonly used AC motors or D
To provide a variable magnification device having two stages of variable magnification, targeting two types of commonly used limited variable magnification, using an inexpensive motor such as a C motor whose position cannot be regulated.

A two-step 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 object-to-image distance g between the original surface side and the surface side, it is necessary to stop moving the entire zoom lens thread in the original axis direction. At the same time, the correlation between the a number of lens groups that make up the zoom lens string must also be changed.

Fig. 1U shows changes in the amount of movement in the optical axis direction and the correlation between each lens group depending on the magnification ratio, regarding a zoom lens string consisting of two lens groups.

Assuming that the positions of the lens group b and the second lens group C at the same magnification of the zoom lens system α are A-B, when the original horizontal lens is reduced to a constant magnification without changing the object-image distance, only a certain amount The zoom lens thread α must be moved parallel to the optical axis toward the image forming surface, and the first lens group and second lens group C must also be moved to positions C and D gt.

Furthermore, when positioning the vine 41 on the copying machine, it is easier to perform one operation and mechanically desirable if the vine 41 can be set in one direction regardless of the size of the vine or the copying magnification. To do this, the entire zoom lens system α must be moved in a direction perpendicular to the original axis.

FIG. 2 will be explained. Let the position of the zoom lens thread at the same magnification be -iH, and let the position of the zoom lens thread at the reduced magnification be [K]. By moving the zoom lens thread α in parallel by an amount 2 corresponding to the magnification changer in the direction perpendicular to the optical axis, and placing it at the reference position of the edges A2 of the images A and B, the image AI of the edge A can be obtained. The image of wheat with variable magnification is also focused in a fixed position. Therefore, the position of the edge of the copy paper may be set at a constant position with reference to A1. The amount of parallel movement X is determined by the following equation. Assuming that the length between the optical axis O and the original edge at equal magnification is L/2, and the reduction magnification 芩, then (1/2-z): (J/2+z) = 1: m
As shown above, the zoom lens system cL at variable magnification
is a mechanism in which the second lens system C moves by a predetermined amount according to the magnification ratio when the first lens system is moved in the optical axis direction, and a mechanism in which the entire zoom lens system α moves by a predetermined 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.

6 and 4 show the holding and guiding mechanism for the lens**.

The second lens barrel 4 with the second lens #1 attached and the second
The second lens barrel 4 to which the lens group 3 is attached is slidably fitted together so that their original axes coincide, and the lens barrel 2 and the second lens barrel 4 constitute a zoom lens system. ing.

The moving means indicated by the arrow F in the original axial direction attaches the outer periphery of the lens barrel 2 to the holding member 5, and the outer periphery of the second lens barrel 4 to the holding member 6. A frame portion 5cL is formed at the lower end of the holding member 5, and a concave horizontal frame portion 6cL is formed at the lower end of the holding member 6. The arches of the bridge parts 5a and 6a are slidable on guide rods 7 and 8, which are bridged parallel to the lens barrels 2 and 4 between the mounts 9 and 10 attached to the movable plate 19 *b. are combined. This guide m7
, 8 are moved in the direction of the arrow F in the direction of the optical axis by sliding the holding members 5, 6.

The means for moving the arrow E in the direction perpendicular to the optical axis will be explained.

The lower end of the pedestal 9 is slidably fitted to a guide rod 11 which is disposed perpendicularly to the lens tube 2.4 between the pedestals 41 and 42 attached to the base plate 20. 1
A roller 16 is attached to the lower end of the base plate 20 so as to roll on the base plate 20. Note that a beam dome 20a is formed on the base plate 20, and the bridge portion 5
A cam follower 18 is rotatably attached to the lower surface of cL. A cam follower 18 is pressed against the lead cam 20i by a tension coil spring 17 between the base plate 19 and the base plate 20.

By moving the cam follower 18 on the lead cam 20G, the cam follower 18 moves in a direction perpendicular to the optical axis.

A normal AC or DC motor 21 is used for the drive gap. The output shaft of the motor 21 is connected to a siraohm 23 by a coupling 22.

To explain these related parts in detail with reference to FIG. 5, a worm wheel shaft 24 is fixed to the movable plate 19 with a screw 36, and a wheel 25 is rotatably fitted to the worm wheel shaft 24. A lever 26 for operating the microswitches 34, 351 is fixed to the wheel 25 by a set screw 37. The drive pulley 27 is also fixed to the wheel 25 by a set screw 38. A retaining ring 29 is attached to the upper end of the worm wheel @24 to prevent the wheel 25 from slipping off. The wire 28 is wrapped around the drive pulley 27 several times.

The central part of the wound wire is wrapped once around the screw 39 and fixed to the drive pulley 27 to prevent the wire 28 and the drive pulley 27 from slipping. wire 2
8 are stretched in opposite directions and pulleys 30, 31'
After t-, the tension shown in FIG. 6 is applied.

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 you now move from the same magnification position to the reduced magnification position,
By starting the motor 21, which electrically performs forward and reverse rotation, and rotating the drive pulley 27 counterclockwise, the holding member 5 is moved rightward. In order to maintain the distance between the set positions C and D of the second lens group C, a stopper 13 that is adjustable on the holding member 6 is used to move the holding member 6 to the right in the same way as the holding member 5. In order to hold the zoom lens system at the set position 1 during reduction/magnification as shown in FIG. However, the motor 21 continues to rotate and after pulling the tension coil spring 33 by an appropriate amount, the lever 2
6 operates the stop microswitch 35, and the t1 motor 21 is stopped. After the motor stops, the tension coil spring 33
The worm 23 and the worm wheel 25 prevent the drive pulley 27 from rotating clockwise due to the force.

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

The cam follower 18 moves from the cam follower position 18t0L at the same magnification to the cam follower position 186 at the small magnification by 1 km above the lead cam 20cL as the holding member 5 moves, in a direction perpendicular to the original axis in FIG. movement of t
zt-Complete.

To move from the reduced magnification to the same magnification, the drive pulley 27 is rotated clockwise by the motor 21, and the stopper 15 provided on the holding member 4 moves the first lun group and the second lun group at the same magnification as shown in FIG. The lens group C is held accurately in position A-Bt, and the stopper 14 provided on the pedestal 10 is used to accurately hold the zoom lens system setting position H at the same magnification as shown in FIG.

Furthermore, since the stoppers 12, 13 and 14, 15 are adjustable, it is possible to easily adjust the focus at each magnification and control the 1x magnification, which has the advantage of increasing work efficiency.

As mentioned above, this invention deals with the same magnification and reduced magnification.
Although stepwise magnification has been described, desired two-step magnification can be achieved by changing the amount of movement. Since a normal motor is used, the control becomes t[l, which makes it cheaper.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the amount of movement in the optical axis direction according to the magnification and the change in the correlation between each lens group in a zoom lens system consisting of two lens groups, and Figure 2 is a diagram showing the change in the correlation between each lens group. FIG. 6 is a perspective view of a moving mechanism showing an embodiment of the present invention; FIG. 4 is a sectional view showing a holding and guiding mechanism for the zoom lens system; FIG. 5 is a drive diagram. Boo II A partial exploded perspective view, FIG. 6 is a plan view showing the state where it is positioned at the same magnification position, and FIG. 7 is a plan view showing the state where it is positioned at the reduced magnification position. 1: 1st lens group 2: 2nd lens group 5.6: Holding member 12.13. ．． 14, 15: Stopper 18: Cam follower 19: Moving plate 20: Base plate 21: Motor 26: Lever 27: Drive pulley 28: 9 ear 32.31 tension 9 coil spring 34.35! Arm Ikrositch Spear 4 Figure Ya 3 Figure

Claims (1)

[Claims] In a variable magnification device for a copying machine that uses a zoom lens string consisting of at least two lens groups in the optical system, the zoom lens system is moved in the optical axis direction and the optical axis using a drive motor that cannot regulate its position as the drive source. K was designed so that two stages of magnification can be obtained by moving in the 1f angle direction.
t-characteristic double layered oak.