JPH0717077Y2 - Variable copying machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of use) The present invention relates to a white frame forming device for an electrophotographic copying machine, and in particular, it forms a white frame outside the image area in an electrophotographic copying machine with variable copy magnification. It relates to a device for doing.

(Prior Art) Generally, in a copying machine capable of variable magnification, a large non-image area is generated on one side or both sides in the axial direction of the photoconductor in the case of reduction copying, as compared with the case of equal copying.

Since this non-image area is not exposed, it is in a charged state, and as it is, it is developed and toner adheres.
As a result, the toner consumption increases, and the cleaning device has an increased load, resulting in poor cleaning, insufficient capacity of the cleaning device, and when toner is transferred to a transfer paper larger than the image, toner in the non-image area adheres to the transfer paper. Various problems occur in which a black frame is formed and an unsightly copy state results.

Conventionally, in this type of copying machine, a plurality of lamps are arranged along the axial direction of the photoconductor, and these lamps are selectively turned on to expose and discharge the non-image area to prevent toner adhesion. A white frame forming device is used. In this case, the exposure area cannot be changed steplessly.

In order to make an almost stepless change, a method is used in which light sources such as LED elements that can expose only a small area are closely arranged and switched. However, in this case, it is only approximate and the overlap between the exposure area and the image area changes. In addition, a white frame with a sharp edge cannot be formed unless an element such as an LED is brought close to the photoconductor and light is condensed using a lens. In addition, since a large number of LED elements are required, reliability deteriorates due to failure of a single item and life, and an electric circuit for control is required, which complicates the device.

Therefore, the following apparatus has been proposed as a white frame forming apparatus used in a stepless variable magnification copying machine. That is,
Arrange a light source that emits light along the axial direction on the photoconductor,
A window for forming a white frame is provided between the light source and the photoconductor, and a slit plate capable of opening / closing a part or all of the window is provided. The slit plate is moved by a motor, and the movement of the motor is controlled by a microcomputer according to a set magnification, so that the exposure area for forming a white frame can be continuously adjusted. .

In this case, a motor and a circuit for controlling the motor are required, which increases the cost. In addition, when a pulse motor is used to perform highly accurate control, a reference position detection means is required, and it is necessary to return the reference position once and then move it again to the set position, which complicates the operation. .

Further, as a method similar to the above-mentioned method, the position of the slit plate is not controlled by a motor, but the movement of the lens at the time of zooming is converted into the movement of the slit plate to expose a white frame. Have been proposed for continuous regulation. However, in the conventional embodiment, since the slit plate also moves in response to the movement of the lens during the enlargement copy that does not require the formation of the white frame, an extra space for moving the slit plate is required.

(Purpose of Invention) The present invention aims to solve the above problems.

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a lens optical system having a lens for forming an image of a document on a photoconductor, and a non-image portion for irradiating the end of the photoconductor with light. A restricting member that restricts the width of the light that is transmitted, and a transmitting unit that transmits the driving force generated by the movement of the lens optical system for moving the restricting member to the restricting member. In a variable-magnification copying apparatus in which a lens optical system moves, the transmission means engages with the lens optical system only at the time of reduction magnification, and the regulation member has a reduction magnification so that the regulation width of light differs at an arbitrary reduction magnification. It is characterized in that, at the time of setting, it always moves in conjunction with the movement of the lens optical system.

(Embodiment) FIG. 2 is a schematic sectional view of a copying machine embodying the present invention.
The copying mechanism will be briefly described.

The transfer sheet P fed by the sheet feeding device 1 or 2 is sent to the photosensitive drum 21 by the registration roller 20 in time with the image on the photosensitive drum 21.

The toner on the photosensitive drum 21 is transferred onto the transfer paper P in the transfer unit 3.
Is transcribed to. The transfer paper P passes through the transport unit 4, and the toner is fixed on the transfer paper by the pair of fixing rollers 5 and 5 ', and is discharged to the outside of the main body. The toner other than that transferred from the photosensitive drum 21 to the transfer paper P is collected by the cleaner unit 8. Photosensitive drum
21 is charged by the charger 9.

The white frame forming device 10 irradiates a portion of the photosensitive drum 21 outside the image area with light to remove charges in an unnecessary portion of the image.
The document 0 on the document glass 12 is illuminated by the illumination unit 11, and the first mirror 13, the second mirror 14, the third mirror 15, the zoom lens 19, the fourth mirror 16, the fifth mirror 17, and the sixth mirror 18 are illuminated. An image is formed on the surface of the photosensitive drum 21 via.

The electric charge escapes from the light-irradiated portion of the photosensitive drum 21 to form a latent image. The first developing device 6 and the second developing device 7 are filled with toners T and T ', respectively. First developing device 6 and second
The developing device is selectively held near the photosensitive drum 21 by a switching device (not shown), and the latent image on the photosensitive drum 21 is developed by the toner T or the toner T '.

FIG. 1 and FIG. 4 are interlocking explanatory views of the lens moving mechanism and the slit moving mechanism.

The zoom lens 21 is fixed on the lens base 28. The lens base 28 moves on the rail 27 by the guide portion 28b.
The lens base 28 fixing portion 28a is fixed to the lens wire 24. The lens wire 24 is wound around the drive pulley 23 via pulleys 25 and 26. When the magnification is set in the operation unit (not shown) and the copy start key is pressed, the lens motor 22 rotates. The lens base flag 28e moves to a position where the position detection sensor 49 is cut off (this position is called the home position of the zoom lens 21). The lens motor 22 is reversely rotated by a signal from the position detection sensor 49, and the lens base 28 is moved to a position corresponding to the set magnification and stopped.
When the lens base 28 moves, the zoom ring 30 of the zoom lens 21 rotates due to the relative movement of the zoom base 51 supported by the zoom rail 29 and the lens base 28.
With the above operation, the zoom lens 21 sets the original 0 on the original glass 12
Image on the photosensitive drum 21.

As the zoom lens 21 and the lens base 28 move from the home position in the direction of arrow A, the copy magnification changes to enlargement, equal magnification, or reduction. In this embodiment, the maximum original size is A3 and the maximum transfer paper size is B4, and the white frame formation is started from the reduction ratio of about 85%. When the lens base 28 moves to a position corresponding to a reduction ratio of about 95%, the lens base tilt part
The tip portion 29b of the swing arm 29 contacts 28C. Swing arm
29 is rotatably supported about an axis 42. Swing arm 29
Is molded by plastic, and the thin plate portion 29a is held by the fixing portion 52 on the main body side. Since the thin plate portion 29a has a spring property, it does not prevent the swing arm 29 from moving around the shaft 42. When the tip portion 29b moves to a position where it does not come into contact with the lens base 28, the swinging arm 29 is caused by the spring property of the thin plate portion 29a.
Returns to its predetermined position. When the lens base 28 moves further, the tip portion 29b moves along the straight portion 28f of the lens base 28. At this position, the first gear 30 rotatably supported by the shaft portion of the swing arm 29 and 29c is the rack portion of the lens base 28.
Holds at a height of 28d. Further, when the lens base 28 moves, the rack portion 28d of the lens base 28 and the first gear 30 mesh with each other.

FIGS. 3A and 3B are operation explanatory views of the white frame forming device near the photosensitive drum 21.

As described above, the movement of the zoom lens 21 is transmitted to the first gear 30 via the rack portion 28d of the lens base 28. 1st gear 3
The rotation of 0 is transmitted to the second gear 31. The second gear 31 is coaxially coupled to the third gear 32. The third gear 32 meshes with the slit track 33. A slit 34 is adjustably attached to the slit track 33.

Variations in the lamp position, variations in component accuracy, lens position deviations due to adjustment of the optical system, etc. are adjusted by shifting the relative positions of the slit track 33 and the slit 34 so that a white frame is formed at an appropriate position. 2nd gear 31 and 3rd gear
A wire 35 is wound around the connecting portion of 32 and is locked to the main body via a spring 36. The second gear 31 and the second gear are always urged in one direction around the axis by the wire 35 and the spring 36. Therefore, when the rack portion 28d and the first gear 30 are not engaged with each other, the slit track 33 is always biased in a fixed direction and abuts on the stopper portion (not shown) to stop.

One surface of the shutter 47 is a reflecting surface, and can swing around the shaft 52.

The operation of forming a white frame during reduction copying will be described with reference to FIGS. 3 (a) and 3 (b).

The untransferred toner on the surface of the photosensitive drum 21 is collected by the cleaner unit 8. The light from the pre-exposure lamp is applied to the surface of the photosensitive drum 21 through the openings 46 and 45. Therefore, the residual charge on the photosensitive drum 21 escapes by the light of the pre-exposure lamp 42.
The unevenness of the potential on 21 disappears. Next, with the charger 9,
A uniform charge is placed on the photosensitive drum 21.

First, in the stage before the image on the original 0 by scanning is formed on the photosensitive drum, the shutter 47 is raised upward as shown in FIG. 3 (a). The light from the pre-exposure lamp 42 is open
The light passes through 48, is reflected by the shutter 47, and is irradiated onto the photosensitive drum 21. The shutter 47 has a width that illuminates the entire region in the longitudinal direction of the shaft of the photosensitive drum 21. Since the charges on the surface of the photosensitive drum 21 escape, a white frame on the front end side is formed.

With respect to the timing when the document scanning is started and the leading edge of the document 0 is projected on the photosensitive drum, the projection position of the document 0 and the shutter 47 are read.
Thus, the shutter 47 closes and moves to the position shown in FIG. 3 (b) at the timing when the deviation amount of the light irradiation position is temporally corrected. The shutter 47 is opened and closed by a solenoid (not shown). The shutter 47 is closed by slightly shifting the timing to the side where the light enters the image side so that the tip of the transfer sheet P becomes white about 2 mm. The white of the leading edge of the transfer paper P makes the fixing roller pair
The transfer paper P is prevented from being wrapped around 5, 5 '.

The opening 38 is closed by the slit 34 at the time of enlargement and reduction of about 85% to about 1: 1. When a reduction ratio of 85% or less is set, the aperture changes as the zoom lens 21 moves.
38 opens. Strictly speaking,
The relationship of the width of the white frame that should be formed at the edge of the transfer paper due to reduction is
Although the relationship is as shown in the graph of the figure, in the present embodiment, the above-mentioned mechanism approximates a linear relationship and adjusts so that the white frame edge is exactly on the line of the image end or the white frame is slightly obscured by the image. is doing. Also, even if the zoom lens movement amount and the white frame width at the time of reduction are changed to a relationship that can be approximated by a straight line, the absolute value itself is different, so when transmitting rotational movement from the second gear to the third gear, the ratio of the number of teeth is approximate The amount of movement is converted by setting the slope k of.

When the image exposure is finally performed on the photosensitive drum 21 from the sixth mirror 18 through the optical system, the light of the pre-exposure lamp 42 passes through the opening 48, the upper portion of the shutter 47, and the opening 43. The black eraser mirror 37 is illuminated. Light is a black eraser mirror
It is reflected by 37 and is irradiated onto the photosensitive drum 21 through the opening 38 opened corresponding to the reduction magnification.

In this embodiment, the transfer belt P is separated from the photosensitive drum 21 by a separation belt (not shown). If such a partial toner is present in the separation belt, the transfer paper is stained and the separation belt is broken. Therefore, the light of the pre-exposure lamp 42 is reflected by the sharp cut mirror 39 shown in FIG. 4 and the light is always irradiated with a constant width on the photosensitive drum 21 in the same manner as the white frame formation at the time of reduction. There is. Since the position of the light emitting point of the pre-exposure lamp 42 varies, the width of the light is first adjusted by the sharp cut slit 40.

When scanning of the manuscript 0 is completed, the shutter 47 is again shown in FIG. 1 (a).
Return to the position. Therefore, the light is irradiated after the trailing edge of the image, and the consumption of the toner is prevented. If the shutter 9 is open, the black eraser mirror 37 and the sharp cut mirror 39
The light of the pre-exposure lamp 42 never enters. Therefore, it is possible to prevent a problem that an extremely strong light amount hits a part of the photosensitive drum 21 and deteriorates.

Further, a region where the light is irradiated to the photosensitive drum 21 after being reflected by the shutter 47, the blackening mirror 37 and the sharp cut mirror.
The area reflected by 39 and irradiated with light on the photosensitive drum 21 overlaps or is a blackening mirror 37 and a sharp cut mirror.
The shutter 47, the black erasing mirror 37, and the sharp cut mirror 39 are arranged so that the region irradiated by the light from 39 is on the upstream side.
The light is reflected by the sharp cut mirror 39, and the light is always irradiated on the photosensitive drum 21 with a constant width. Since the position of the light emitting point of the pre-exposure lamp 42 varies, the width of the light is first adjusted by the sharp cut slit 40.

When scanning of the manuscript 0 is completed, the shutter 47 is again shown in FIG. 1 (a).
Return to the position. Therefore, the light is irradiated after the trailing edge of the image, and the consumption of the toner is prevented. If the shutter 49 is open, the black eraser mirror 37 and the sharp cut mirror 39
The light of the pre-exposure lamp 42 never enters. Therefore, it is possible to prevent a problem that an extremely strong light amount hits a part of the photosensitive drum 21 and deteriorates.

Further, a region where the light is irradiated to the photosensitive drum 21 after being reflected by the shutter 47, the blackening mirror 37 and the sharp cut mirror.
The area reflected by 39 and irradiated with light on the photosensitive drum 21 overlaps or is a blackening mirror 37 and a sharp cut mirror.
The shutter 47, the black erasing mirror 37, and the sharp cut mirror 39 are arranged so that the region irradiated by the light from 39 is on the upstream side.
The angle of is set.

Therefore, when the shutter 47 opens and closes, a state in which none of the light reflected from the shutter 47, the blackout mirror 37, and the sharp cut mirror 39 reaches the photosensitive drum 21 as a time series, but on the photosensitive drum 21. There is no light-exposed area at the switching boundary.

In the above-described embodiment, since the maximum original size and the maximum transfer paper size are different, the lens moving mechanism and the slit moving mechanism are interlocked with each other from the time of 95% reduction slightly before the 85% reduction that requires the formation of a white frame. However, when the maximum document size and the maximum transfer sheet size are the same, the lens moving mechanism and the slit moving mechanism are interlocked with each other from near the same size position, that is, from a position slightly closer to the enlargement side.

(Effect of the Invention) As described above, according to the present invention, it is possible to eliminate the waste of the moving space due to the movement of the regulating member at the time of enlarging the magnification, and to always obtain the light of the optimum width at the arbitrary reducing magnification. The edge of the photoconductor can be irradiated.

[Brief description of drawings]

1 and 4 are interlocking explanatory views of a lens moving mechanism and a slit moving mechanism, FIG. 2 is a schematic sectional view of an embodiment, and FIGS. 3A and 3B are operation explanations of a white frame forming device. Figures and 5 are graphs showing the relationship between the lens movement distance and the white frame width. 21 is a zoom lens, 28 is a lens base, 28d is a rack part, 29
Is a swinging arm, 30 is a first gear, 31 is a second gear, 33 is a slit truss, and 34 is a slit plate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-58-90664 (JP, A) JP-A-62-47666 (JP, A) JP-A-56-110953 (JP, A) JP-A-54- 159234 (JP, A) JP 50-147336 (JP, A) JP 60-49361 (JP, A) JP 62-63956 (JP, A) JP 58-70251 (JP, A) JP-A-59-201038 (JP, A) JP-A-59-201037 (JP, A) Actually open 61-137963 (JP, U) Actually open 62-41157 (JP, U) Actually open 63-4557 (JP, U) Japanese Patent Publication Sho 52-28665 (JP, B2)

Claims (1)

[Scope of utility model registration request] 1. A lens optical system having a lens for forming an original image on a photoconductor, a regulation member for regulating the width of light irradiated to form a non-image portion at the end of the photoconductor, and A variable-magnification copying apparatus in which the lens optical system moves in accordance with an arbitrary enlargement magnification and reduction magnification, and a transmission unit that transmits the driving force due to the movement of the lens optical system to the regulation member to move the regulation member. The transmission member engages with the lens optical system only when the reduction magnification is set, and the regulation member is always linked with the movement of the lens optical system when the reduction magnification is set so that the regulation width of the light is different at an arbitrary reduction magnification. A variable-duplex copying machine characterized in that it can be moved as it moves.