JPS61172133A - Copying machine with zoom variable power - Google Patents

Abstract

PURPOSE:To eliminate a magnification error due to the backlash of a gear, etc., by moving the backlash of a lens drive system toward the enlargement side during shifting a lens at the time of changing a magnification from a reduction magnification to an enlargement one, and moving a lens to a specified magnification position after said backlash is moved toward the reduction side at the time of changing from the enlargement to reduction. CONSTITUTION:A wire loop 14 wound on a pulley fixed on a spindle 45, which is rotated and driven through a gear, etc., from a lens drive source 40, moves a lens 27. A wire loop 51 wound on a pulley installed on a member, which is engaged with a rotary plate cam 42 fixed on the spindle 45 and executes a straight line motion, carries out the variable power shifting of a mirror. At the time of changing the reduction magnification to the enlargement one. the backlash of the lens drive system is moved toward the enlargement side, and the lens is shifted to the specified magnification position. On the other hand, when the enlargement magnification is changed to the reduction, said backlash is moved toward the reduction side, and the lens is sifted to said position.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a zoom magnification copying system that enables zoom magnification of enlargement and reduction by scanning after moving the lens and some mirrors constituting the exposure optical system. Regarding machines.

A typical exposure system of a prior art electrophotographic copying machine will be explained with reference to FIG. A first mirror 24, a second mirror 25, a third mirror 26, an imaging lens 27, and a fourth mirror 2 arranged as shown in FIG.
The exposure lamp 23 and the first mirror 24 are integrally connected to the first scanner 3.
0 and extends in the document scanning direction.
The second mirror 25 and the third mirror 26 are integrally carried by a second scanner 61, and the second mirror 25 and the third mirror 26 are moved at a constant speed V/2 in the same direction in synchronization with the first scanner 30. By rotating the photoreceptor drum 29 at a circumferential speed V in the direction shown by the arrow, the document is scanned, an electrostatic latent image corresponding to the document image is formed on the photoreceptor drum 29, and an electronic A photographic process creates a copy.

In that case, in order to obtain a so-called in-focus copy image, the exposure optical system must satisfy the following equation.

Here, a: Distance of the lens salt from the original surface b = Distance from the lens to the imaging plane on the photoreceptor f: Focal length of the lens Also, the distance from the original surface to the imaging plane, that is, the conjugate length is , Here, m: Copying magnification (=-) In order to perform variable magnification copying, in Fig. 2, lens 2
7 and the second scanner 31 carrying the second and sixth mirrors 25 and 26 in parallel to the scanning direction according to the copying magnification m so as to satisfy the above equations (1) and (2). It is necessary to move it like this.

As is clear from equation (2), the conjugate length is equal to the size (m=1
) is the minimum, and increases as the magnification departs from 1 both during enlargement and reduction. FIG. 6 shows the relationship between magnification and conjugate length.

Therefore, when zooming down, the lens 2 in FIG.
7 is moved from the same magnification position shown by the solid line to a position approaching the fourth mirror 28 shown by 27', and the second scanner 61 carrying the second and third mirrors 25 and 26 is moved to the same magnification position shown by the solid line. From the hour position, for example, as shown at 31', lens 2
It is only necessary to move it in a direction away from 7. Also, when changing magnification, the lens 27 is moved from the same magnification position to the third mirror 26.
For example, the second scanner 31 needs to be moved in a direction away from the lens 27 as in the case of reduction.

In order to move the lens and the second scanner in relation to each other as described above, the lens bracket supporting the lens and the second scanner are moved by a feed screw for each, and each feed screw is moved by a separate pulse. By the motor,
An apparatus is known in which a lens and a second scanner are moved by inputting a pulse number corresponding to a movement amount corresponding to a desired magnification. However, this method requires a separate pulse motor to move the lens and mirror, and the number of pulses to be input is also different, resulting in an increase in cost.

As an improved variable power drive mechanism, one having the structure shown in FIGS. 4 to 6 is known. In this device, a worm wheel 44 is engaged with a worm 43 driven by a lens driver using a stepping motor.

A variable power cam pulley 13 and a mirror shift cam 46 are integrally fixed to a shaft 45 to which a worm wheel 44 is fixed.

A lens drive wire 14 is wound around the variable power cam pulley 13 and the other driven pulley.

The lens drive wire 14 is attached to the wire clamp bracket 4
is clamped via a wire clamp 15. A lens bracket 1 carrying a lens 27 is slidably supported by a guide rod 2 provided parallel to the scanning direction, and a lens positioning bracket 3 is fixed thereto. Two guide pins 6 are implanted in the lens positioning bracket 3, and are slidably fitted into two elongated holes 4a provided in parallel to the guide rod 2 in the wire clamp bracket 4, respectively. One side and wire clamp 15
A spring 5 is stretched between the lens bracket 1 and the lens bracket 1 to position and hold the lens bracket 1 at a position where the guide pin 6 abuts one end of the elongated hole 4a. The illustrated example is a one-sided copying machine, and the lens is moved to the guide rod 2 according to the magnification ratio.
Move the lens bracket 1 in a direction perpendicular to the
A lens cam 47 and a lateral guide rod 48 are provided.

A cam follower 50 attached to a cam bracket 49 that is slidably supported in the scanning direction with respect to the machine frame engages with the mirror shift cam 46, and a mirror shift wire 51 is wound around the bracket 49. Moving pulley 52
is pivoted.

Therefore, when changing the copying magnification, by inputting the number of pulses corresponding to the magnification to the lens drive motor 40, the timing pulley 41, timing belt 42, worm 45,
A shaft 45 is rotationally driven via a worm wheel 44,
The variable power cam pulley 13 and the mirror shift cam 46 fixed to this shaft rotate at the same angle at the same time. Variable power cam pulley 1
3, the lens drive wire 14 moves, and the lens bracket 1 moves to a position corresponding to a desired magnification via the wire clamp bracket 4 clamped thereto and the lens positioning bracket 3.

On the other hand, as the mirror shift cam 46 rotates, the movable pulley 52 is displaced via the cam 7 lower 50 and the cam bracket 49, and the mirror shift wire 51 is moved. When the mirror shift wire 51 moves, the wire arrangement shown in FIG. 6 causes one streak.

The mirror shift boot 1 56, which is rotationally biased by 54, rotates and rotates a pulley 55 that is pivotally supported on the second scanner 31 via a wire, thereby moving the second scanner 31 by a predetermined amount according to the magnification. let

FIG. 7 shows the outline of the mirror shift cam 46 of this device. As is clear from equation (2) and Figure 6, this shape is
The amount of protrusion is the maximum at the same magnification, and becomes smaller continuously as the magnification moves away from 1 on both sides of enlargement and reduction.

In other words, the curvature force is maximum at the same magnification, and becomes smaller continuously on both the enlargement and reduction sides. Therefore, the pressure angle relative to the cam follower is zero at the same magnification, and increases as the distance from the same magnification increases, but the sign of the pressure angle becomes opposite between the enlargement side and the reduction side across the same magnification.

The cam 7 is attached to the cam 7 by the tension of the mirror shift wire 51 due to the force of the spring 54 shown in FIG.
is always in pressure contact with the cam 46.

Therefore, the direction of the cam pressure angle is constant when moving within the reduction range or the enlargement range, and the cam is always receiving pressing force from the cam 7 lower.
The backlash between the worm 43 and the worm wheel 44 is always biased in a fixed direction. However, when moving beyond the same magnification, such as from reduction to enlargement or from enlargement to reduction, the direction of the pressure angle is reversed at the same magnification position, and therefore the direction of backlash is reversed.

As a result, an error occurs in the amount of lens movement relative to the number of input pulses to the lens drive motor 40 by the amount of backlash, which appears as a magnification error.

In a variable magnification drive device in which the lens and mirror are moved by separate feed screws, the screw backlash must be removed at a predetermined position according to the magnification, regardless of the direction of magnification change between enlargement and reduction. However, in the above-mentioned variable magnification device where the direction of the backlash is reversed from the same magnification position as in the device with the above configuration, this method is not possible. It is not possible to remove backlash.

Purpose of the Invention In view of the above-mentioned circumstances, it is an object of the present invention to provide a zoom magnification copying machine that can eliminate magnification errors due to backlash of gears, etc. in a zoom magnification device using a moving lens and mirror system as described above. purpose.

Structure In order to achieve the above object, the present invention moves the backlash of the lens drive system to the enlargement side during lens movement when changing the magnification in the variable magnification mechanism of the above-mentioned structure from the reduction magnification to the enlargement magnification. The present invention is characterized in that when changing from a magnification to a reduction magnification, the backlash is moved to the reduction side and then moved to a designated magnification position.

Hereinafter, the present invention will be explained in detail using the drawings.

FIGS. 1(a) to 1(i) are diagrams showing the lens movement process when changing the copying magnification in various modes. In the figure, ○ indicates the starting position of the lens, . indicates the final lens stop position, and ◯ indicates the lens temporary stop position. The center of each figure is the same magnification position;
The left side is the reduction side, and the right side is the expansion side. The same magnification position is known by the home sensor shown at 56 in FIG. 5, which detects L when moving from the enlarged side to the reduced side, and detects H when moved from the reduced side to the enlarged side. be able to.

(a) When moving from 1x to 1x when power is turned on or from 1x to 1x, first rotate the lens drive motor 40 by an appropriate pulse l (n pulses) on the enlargement side to move the lens. Send and bring the backlash to the expansion side. The motor is briefly stopped at that position, and then the motor is reversed and stopped at the position where the home sensor detects L.

(b) From the same size to the reduced size At the same size position, the backlash is closer to the enlargement side. Therefore, if it is moved directly to the desired reduction position, an error corresponding to the backlash will occur. In this case, -just move the appropriate pulse 1k (n pulses) to the reduction side to bring the backlash to the reduction side, then reverse it and stop at the position where the home sensor detects H (equal 'x position), From this position, it is moved again to the desired magnification position.

(C) Same magnification → enlargement Since the backlash at the same magnification position is closer to the enlargement side, the image is moved to the desired magnification position.

(d) Reduction → Reduction Since the backlash at the reduction position is closer to the reduction side, the backlash at the reduction position is moved to the desired position in either direction during the movement between reduction and reduction.

(,) Reduction→The backlash at the same size reduction position is closer to the reduction side, so if you move it to the same size position, the backlash direction at the same size position will remain closer to the reduction side. become. In order to keep the backlash at the same magnification position toward the enlarged side,
In this case as well, when the home sensor detects H (at the time when the @double position is reached), an appropriate pulse (n pulse) is caused to overrun to the expansion side, and the backlash is brought to the expansion side and stopped. From there, the motor is reversed and stopped when the home sensor detects L.

(f) As in the case of reduction→enlargement/reduction→equal magnification, stop at the equal magnification position with the -tan backlash moved toward the enlargement side, and move from there to the desired enlargement position.

(g) Enlargement→reduction In this case, the movement is in the completely opposite direction to the above-mentioned (f). In other words, it is brought to the backlash on the reduction side and returned to the same magnification position, and then moved to the desired reduction position.

(h) Enlarge → The backlash at the 1x magnification position is closer to the enlargement side, so move it directly to the 1x magnification position.

(Backlash at the same magnification position should be moved to the enlarged side.

) (i) Enlargement→Enlargement Since the backlash is closer to the enlargement side, the movement between enlargement and enlargement is performed in either direction to the desired position. (Same as case (d).) Effect As described above, according to the present invention, the lens is moved by the variable magnification cam pulley provided on the shaft driven by the lens movement motor via a gear, etc., and the lens is fixed on the same shaft. In zoom magnification copying machines that change magnification by moving the mirror using a mirror shift cam, backlash from gears, etc. is removed when changing magnification from enlargement to reduction beyond the same magnification position, or vice versa, and magnification error is reduced. No images can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the lens movement process for various copying magnification changing modes according to the present invention, Fig. 2 is a cross-sectional view showing the configuration of the aperture system of a general variable magnification copying machine, and Fig. 6 is a diagram showing the magnification and FIG. 4 is a curve diagram showing the relationship between conjugate lengths; FIG.
Figure 6 is a perspective view of the mirror, Figure 6 is a perspective view showing the adjustment mechanism for moving the mirror, and Figure 7 is a view of the outside of the mirror shift cam. 13... Variable power cam pulley, 14... Lens drive wire 25... Third mirror 26... Fourth mirror 2
7... Lens 40... Lens drive motor 46... Worm 44... Worm wheel 45... Worm wheel shaft 46... Mirror shift cam 49... Bracket 51... Mirror shift wire 52. ...Pulley 56... Home sensor (d) Reduction - Reduction Figure 1 Small ← Same size → Enlargement - 110 Figure 2 Figure 3 Magnification (m) Figure 6 Volume 7

Claims (1)

[Claims] When changing magnification and zooming, the exposure lens is moved in opposite directions from the same magnification position, and some mirrors are moved in the same direction from the same magnification position to enlarge. This is a zoom variable magnification copying machine that enables zoom reduction, and the movement of the lens described above is carried out by a wire rope wrapped around a pulley fixed to a shaft that is rotationally driven by a lens drive source via a gear etc. The magnification movement of the mirror is performed by a wire rope wrapped around a pulley provided on a member that engages with a rotary plate cam fixed to the shaft to perform linear motion. When changing magnification, move the backlash of the lens drive system to the magnification side while moving the lens when changing from reduction magnification to expansion magnification, and then move the backlash mentioned above to the reduction side when changing from magnification magnification to reduction magnification. A zoom variable magnification copying machine characterized in that the lens is moved to a specified magnification position after the lens is brought to a specified magnification position.