JPH0675462A - Image forming device - Google Patents

Abstract

PURPOSE:To deal with all kinds of copying magnification and the synthesization of many kinds of images without complicating a device by providing a light shielding member capable of moving in a direction perpendicular to the moving direction of a photosensitive body, for allowing a blank exposing means to change exposing width. CONSTITUTION:The blank exposing means 17 is unitized, provided with a lower frame 21, a first sliding shutter 22a, a third sliding shutter 22b and a second sliding shutter 22c, as the light shielding member limiting a passing region in the direction perpendicular to the moving direction of the photosensitive body in a width blank exposure, and arranged in a location where the width blank exposure passes and which is nearest to a photosensitive drum 11, to be slidably moved on a rail supported by the lower frame 21. In other words, the first/second sliding shutters 22a and 22c provided on a part corresponding to an end part in the axial direction of the photosensitive body can be independently moved so that the width of each nonimage part can be independently freely set on the end part in the axial direction of the photosensitive body and various kinds of edits such as the use of only half side of the photosensitive body as an image part besides the varying of power can be executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine, and more particularly to an exposing means for exposing a photosensitive member.

[0002]

2. Description of the Related Art A conventional device of this type is disclosed in Japanese Patent Laid-Open No. 48-712.
No. 40, JP-A-57-201267, etc., a light beam generated from one light source is divided into two by a reflection plate, and each is pre-exposed (the residual charge on the photoconductor before charging is entirely covered). It is configured to irradiate the surface of the photoconductor as an exposure for erasing) and a blank exposure (exposure for erasing only the residual charges other than the image area after charging on the photoconductor).

In Japanese Patent Application Laid-Open No. 48-71240, a blank exposure and a shutter for selectively blocking the blank exposure are used.
Only unnecessary image areas at the front and rear ends of the image formed on the surface of the photoconductor are erased. In addition, JP 57-
In 201267, the shutter is divided into a plurality of parts in the axial direction of the photoconductor in addition to the function described above, and it is possible to selectively block the exposure light, so that it is possible to correspond to a magnified image. .

[0004]

However, in the apparatus disclosed in Japanese Patent Laid-Open No. 48-71240, only the function of erasing the unnecessary image area at the front and rear edges of the image has a function to cope with the magnification change. is there. In addition, JP-A-57-201
In order to deal with various magnification changes with the measures described in Japanese Patent No. 267, shutters corresponding to the number of magnification changes are required.
There is a problem that the device becomes complicated and large.

[0005]

In order to solve the above problems, the present invention provides a movable photosensitive member, a charging unit for charging the photosensitive member, and an upstream side of the charging unit with respect to the moving direction of the photosensitive member. Pre-exposure means for exposing the photoconductor, first and second blank exposure means for exposing the non-image portion of the photoconductor on the downstream side of the charging means in the moving direction of the photoconductor, The light source used in the pre-exposure means, the first blank exposure means, and the second blank exposure means is common, and the first blank exposure means is formed at the end of the image portion in the moving direction of the photoconductor. In the image forming apparatus, the second blank exposing means exposes the non-image portion formed at the end portion of the image portion in the direction orthogonal to the moving direction of the photoconductor. hand It is characterized in that it has a light blocking means movable in a direction perpendicular to the moving direction of the photosensitive member for changing the exposure width.

[0006]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of an image forming apparatus to which the present invention is applied. In FIG. 1, the document O placed on the document table 1 is illuminated by a light source 4 provided in the first scanning unit 3, and the image light from the illuminated document O is scanned by the first scanning unit 3.
It is reflected by the reflection mirror 5 provided in the. The image light from the reflection mirror 5 is reflected and reflected by the reflection mirrors 7 and 8 provided in the second scanning means 6, and the image light is charged by the charger 12 via the lens 9 and the reflection mirror 10. 11 is exposed, and a latent image is formed on the photoconductor 11. The first scanning means 3 carries out moving scanning over the entire width of the document table 1, and the second scanning means 6 interlocks with the movement of the first scanning means 3 and carries out moving scanning at half the speed of the first scanning means 3. .

The latent image formed on the photoconductor 11 is the developing device 1.
3 visualizes with toner, and this toner image is transferred to the transfer device 1.
4, the toner on the recording material P is fixed by the fixing device 15, and the recording material P is discharged to the outside of the apparatus. After the transfer, the cleaning device 16 removes residual toner from the photoconductor 11. Reference numeral 17 denotes an exposure unit having one light source, which performs pre-exposure and blank exposure with light from the light source. Here, the pre-exposure is to uniformly expose the photoconductor 11 on the upstream side of the charger 12 in the moving direction of the photoconductor 11, and the blank exposure is to be the blank exposure.
The non-image portion of the image portion end portion (the end portion in the moving direction of the photosensitive member and the end portion in the direction orthogonal to the moving direction of the photosensitive member) formed on the photosensitive member 11 on the downstream side is exposed.

The exposing means 17 will be described in detail below.

FIG. 2 is a main sectional view of the exposure means of this embodiment, 11 is a photosensitive drum, B is an arrow indicating the direction in which the photosensitive drum 11 rotates, and 12 is a charger for uniformly charging the photosensitive drum 11. It is connected to a high voltage power supply (not shown). 1
A pre-exposure optical path 8 irradiates the upstream side 18a of the charger 12 to erase the residual charge before being charged by the charger 12.

Reference numeral 19 denotes a front and rear end blank exposure optical path from the first blank exposure means, and a downstream irradiation position 19a of the charger 12.
To form a non-image portion at the end portion of the image portion with respect to the moving direction of the photosensitive member, that is, the image end surface perpendicular to the moving direction of the photosensitive member.

Numeral 20 is a width blank exposure optical path from the second blank exposure means, which is irradiated to a downstream irradiation position 20a of the charger 12 and is parallel to the moving direction of the photoconductor, that is, a direction orthogonal to the moving direction of the photoconductor. With respect to, the non-image portion at the end of the image portion is formed.

The width blank exposure is always irradiated during image formation, but the front and rear edge blank exposure irradiates only the image front and rear edge positions by the shutter described later, and both photosensitive drums 1 are exposed.
The irradiation areas in the circumferential direction overlap.

The blank exposing means 17 is unitized, 21 is a lower frame, and 22a, 22b and 22c are first slide shutters (light-shielding members for controlling the range of width blank exposure in the direction perpendicular to the moving direction of the photoconductor). Previous),
The third slide shutter (middle) and the second slide shutter (rear) are arranged at positions closest to the photosensitive drum 11 through which width blank exposure passes, and slide on a rail 23 supported by the lower frame 21. The third slide shutter 22b is the first slide shutter 22a,
Since it is movable in the longitudinal direction of the rail 23 while partially engaging with the second slide shutter 22c, it always exists between the first and second slide shutters 22a and 22c, and the width blank exposure is performed. The optical path 20 can pass only outside each of the first and second slide shutters 22a and 22c. Further, the length of the non-exposed area on the surface of the photosensitive member in the direction perpendicular to the moving direction of the photosensitive member when the three slide shutters are completely overlapped is smaller than the width of the minimum size image recording paper used in the image forming apparatus. ing. In addition, the first and second slide shutters 22a,
The length of the non-exposure area on the surface of the photoconductor in the direction perpendicular to the photoconductor moving direction when 22c is in the home position described later is
The width is set to be larger than the width of the maximum size image recording paper used in the image forming apparatus.

Reference numeral 24 is an upper frame of a unit which forms a blank exposing means, and 25 is a lamp which also serves as a light source for pre-exposure, width blank exposure and front and rear end blank exposure (a plurality of light emitting sources in the axial direction of the photosensitive drum 11). 25a is a PCB (Print Circuit Board) that supports the lamp 25.
And is supported by the upper frame 24.

Reference numeral 27 denotes a reflector for guiding the light of the lamp 25 to the width blank exposure irradiation position 20a, which has a quadratic curved surface with a cylindrical cross section so as to focus the light at the irradiation position 20a with a predetermined width.

Reference numerals 26 and 28 are reflectors for guiding the light of the lamp 25 to the front and rear end blank exposure irradiation position 19a.
The cross section has a cylindrical quadratic curved surface shape so as to collect light with a predetermined width on a.

The reflection shades 27 and 28 can be formed of flat members, but the curved shape is preferable because the positional deviation allowable range of the lamp 25 is narrowed and uneven light amount occurs.

The reflection shades 26, 27 and 28 are lightweight,
Made of aluminum sheet metal that is easy to process.

The reflecting caps 26, 27 and 28 are supported at their longitudinal ends by supporting plates (not shown), and the upper frame 24
It is integrated with. 29 is the front and rear end blank exposure optical path 1
A shutter for selectively controlling passage of the light beam 9 is rotatably supported at both ends in the longitudinal direction at a rotation center 30, and is arranged very close to the lamp 25 as a light source. As described above, in this embodiment, the light sources for pre-exposure, front-end / end-edge blank exposure, and width blank exposure by the slide shutter are shared, so that the apparatus can be simplified and downsized.

Reference numeral 31 is a tongue-shaped member which is integrally formed at the longitudinal center of the shutter 29, and a link 33 is engaged through a caulking shaft 32. The link 33 is a caulking shaft 34 of an iron core 34a of a solenoid 34 supported by the upper frame 24.
It is also engaged with b and moves in the direction of arrow C by driving the solenoid 34 to open and close the shutter 29.
Reference numeral 35 is for preventing vibration noise of the shutter 29 itself when the shutter 29 is driven by the shutter damper, and collision with other parts when the shutter 29 rises too far above the open position indicated by the broken line 29a. This component is a slit plate 36 described later.
Since it is attached between the openings of a, it does not interfere with the exposure.

Reference numerals 36a, 36b, 36c and 36d are slit plates, and a schematic configuration in the longitudinal direction is shown in FIG.

Reference numeral 11a is a surface position of the photosensitive drum, and 37a is an opening of the slit plate 36a, so that the lamp 25 can be regarded as a substantially point light source. Reference numerals 37b, 37c, and 37d denote openings of the slit plates 36b, 36c, and 36d. The widths of the openings widen as they come closer to the surface of the photosensitive drum, which can prevent stray light as indicated by 38 and prevent the irradiation position on the drum ( Particularly, the positional accuracy of the portion 39) where the irradiation ranges of the adjacent lamps overlap each other is improved. Reference numeral 40 denotes an ultraviolet ray cut filter provided on the slit plate 36c, which covers a region through which both the front and rear end blank exposure and the width blank exposure pass, and is at a position where two light rays are incident substantially perpendicular to the filter surface. . Therefore, the incident light ray is extremely rarely reflected by the filter surface, and the incident area is minimized, so that the filter area can be small.

FIG. 4 is a top view of this embodiment (A in FIG. 2).
-A cross section), 41 and 42 are wires for moving the first slide shutter (front) 22a and the second slide shutter (rear) 22c, and 43 and 44 are drive pulleys for driving the wires 41 and 42, respectively, the pulse motor 45. , 46
The forward and reverse rotation control and positioning are performed by. 47, 48,
49 and 50 are two sets of idler pulleys for supporting the wires 41 and 42 (two are arranged in the vertical direction in the drawing), which are independently rotatably supported on shafts fixed to the lower frame 21. There is. One end of the wire 41 is engaged with a tension spring 52 that engages with a hooking portion 51a of the first slide shutter 22a, and an idler pulley 47, a drive pulley 43, an idler pulley pulley,
The first slide shutter 22a is wound around the upper pulleys (idler pulleys) in the order of 50 and 48.
The other end engages with the hooking portion 51b of 1 to form a loop-shaped first wire pulley drive system. One end of the wire 42 is engaged with a tension spring 54 that engages with a hooked portion 53a of the second slide shutter 22c, and an idler pulley 48, a drive pulley 44, an idler pulley,
The second slide shutter 22c is wound around the lower pulleys (idler pulleys) in the order of 49, 47 in this order.
The other end engages with the hooking portion 53b of the second wire pulley drive system of another loop shape. Therefore, the two wire pulley drive systems do not interfere with each other, and the first and second slide shutters 22a, 22a,
It is possible to move 22c. Further, a flag 55 is formed on the first slide shutter 22a and a flag 56 is formed on the second slide shutter 22c, and the tip of each flag is fixed to the lower frame 21 as a photointerrupter (front), (rear). ) 57,5
By passing through the sensor points (front) and (rear) 57a, 58a of 8th, the first and second slide shutters 22a, 2a
You can know the absolute position of 2c. Therefore, the first
The second slide shutters 22a and 22c can be moved and stopped at arbitrary positions, and the exposure range in the direction perpendicular to the moving direction of the photoconductor 11 onto the photoconductor 11 by the lamp 25 can be freely controlled.

That is, in this embodiment, since the first and second slide shutters 22a and 22c provided at the portions corresponding to the ends of the photoconductor in the axial direction are individually movable, both ends of the photoconductor in the axial direction are moved. The width of each non-image portion can be independently set, and various image editing can be performed, such as not only changing the magnification but also making only one half of the photosensitive member an image portion.

As described above, as shown in FIG. 4, both ends of the third slide shutter 22b provided between the first and second slide shutters 22a and 22c have a first slide shutter 22a and a second slide shutter 22b. Two
2c are engaged with each other. Specifically, a projection 22b 'is provided at the end of the third slide shutter 22b, and this projection 22b' is formed in the first slide shutter 22b.
It is fitted with an opening 22a 'provided in a. The opening 22a 'of the first slide shutter 22a extends long in the moving direction of the slide shutter.
The protrusion 22b 'is movable within a', and the first slide shutter 22a and the third slide shutter 22a are movable.
b can overlap.

A protrusion 22b "is provided at the other end of the third slide shutter 22b, and this protrusion 22b" is fitted with an opening 22c 'provided in the second slide shutter 22c. ing. The opening 22c 'of the second slide shutter 22c extends long in the moving direction of the slide shutter, and the protrusion 22b "is movable within this opening 22c', so that the second slide shutter 22c and the third slide The third slide shutter 22b itself is not provided with an independent driving means, and the first slide shutter 22a and / or the second slide shutter 22 can overlap.
The third slide shutter 22b is moved by pushing or pulling the protrusions 22b 'and / or 22b "at the end of the opening of c.

FIG. 5 shows the slide shutter 22a of FIG.
22b and 22c are simplified views as seen from arrow C.
Is the width blank exposure light which is regulated by the first and second slide shutters 22a and 22c and is irradiated onto the photosensitive drum 11, and F is the slide shutters 22a, 22b and 22c.
Is the length of the non-exposure area formed by.

Further, since the third slide shutter 22b is engaged with the first and second slide shutters 22a and 22c, the first and third slide shutters 22a and 22c.
b, and the third and second slide shutters 22b, 2
Since there is no gap between 2c, the latent image image on the photoconductor is not erased by the blank exposure light leaking.

FIG. 6 shows a block diagram centering on the control device of this embodiment.

First and second slide shutters 22a, 2
The position control of 2c is as follows. When the power of the image forming apparatus is turned on, the first slide shutter 2 is first detected to detect the reference of each slide shutter position.
2a starts moving in the direction of arrow G, and the second slide shutter 22c starts moving in the direction of arrow H (home position search) (see FIG. 4). Next, from the time when each flag 55, 56 passes before and after the sensor point 57a, 58a, the control device starts counting the number of drive pulses given to the pulse motors 45, 46 and at the same time the pulse motors 45, 4
Stop 6 Then, the first slide shutter 22a is moved to the arrow H by the same amount as the number of drive pulses until the time of stopping.
By moving the second slide shutter 22b in the direction of arrow G in the direction, the front ends of the flags 55 and 56 are stopped at the positions before and after the sensor points 57a and 58a, and the home position is determined. Then, based on this position, the shutter is moved and positioned by the number of drive pulses given to the pulse motors 45 and 46.

That is, since the wire 42 (similarly to the wire 41) is tensioned by the spring 54 as shown in FIG. 7, when moving in the direction of the arrow in the drawing, the spring 5
However, there is a problem that the slide shutter 22c is pulled by 4 and deformation of the spring makes it difficult to perform accurate positioning. In this embodiment, as shown in FIG. 8, the sensor flag 56 (see (a)) is the sensor 5.
The effect of the displacement of the spring is set by making the stroke (b) when it is below 8 the home position, rather by slightly overstroke, then reversing (c) and setting the moment (d) when the sensor is turned on to the home position. Accurate positioning is possible without being affected.

When the image forming apparatus is powered on and the flag 56 is in the sensor 58, the second slide shutter is moved in the direction of arrow G by a specified amount,
The above operation is performed.

When the second slide shutter 22c is moved in the direction of arrow H for positioning, it is controlled so that it always returns to the home position and then moves in the direction of arrow G to stop.

Although the above description of the operation is for the second slide shutter 22c, the same applies to the first slide shutter 22a, and the first slide shutter 22a is symmetrically controlled with the second slide shutter 22c.

Further, when a plurality of slide shutters are moved at the same time (FIG. 9) when copying a reduced layout, for example, when the slide shutters are moved from the state (a) to the state (b) in FIG. , Instead of moving the second slide shutter 22c at the same time,
First, the first slide shutter 22a is moved to a predetermined position, and then the second slide shutter 22c is moved to a predetermined position. In the opposite control, when the second slide shutter 22c is moved first by the stepping motor 46, the third slide shutter 22b is engaged with both the first slide shutter 22a and the second slide shutter 22c, Three
The first slide shutter 22a also moves via the slide shutter 22b. Then, the stepping motor 45 in the stationary state will be rotated. Therefore, by performing the above control, 2
You can move multiple slide shutters without moving one stepping motor. Of course 2
By moving two stepping motors at the same time,
It is possible to move a plurality of shutters at the same time, but at this time, the first and second slide shutters 22a, 22a
2c is controlled so as not to move to the third slide shutter 22b side and collide with each other.

By using the blank exposure means of this embodiment having the above-described structure, the following reduced layout copying can be performed.

FIGS. 10A to 10D show the positions of the slide shutters ((a), (c)) and two images formed on the photoconductor when two images are recorded on one side of one recording sheet. The positions ((b) and (d)) of the image to be read are shown, and (e) is the recording sheet for which the copying operation has been completed. First, when the three slide shutters are overlapped at the position (a), the area on the photoconductor surface corresponding to this shutter area (hatched area in (b))
Since no charge is removed, the image projected on this area at an appropriate reduction ratio becomes as shown in FIG. 7B, which is formed on the recording paper by the copying process of development, transfer and fixing. Next, the slide shutter is moved to the position (c), and the image (d) is formed by the same process as described above. When this image is transferred and fixed on the same surface of the recording paper on which the image of (b) is formed, the image of (e) is formed.

Further, by applying this image forming method, FIG.
It is possible to form an image such as 1 (a). In this case, the copying process of development, transfer, and fixing may be repeated every time one image is formed.
An image in which two originals are arranged as in (c) can be used as the image in FIG. 11A by the image forming method described above. Further, as shown in FIGS. 11 (d) and 11 (e), the images shown in FIG. 11 (a) can be obtained by projecting the images in which two originals are arranged at different positions in the paper feed direction.

FIG. 12 shows a slide shutter of another embodiment of the present invention.

As shown in FIG. 5, since both ends of the first and second slide shutters (front) and (rear) 22a, 22c have a step of dimension d, even if the slide shutters are arranged in symmetrical positions. The position of the end face of the width blank exposed on the photosensitive drum 11 is not symmetrical, and it is necessary to control the position of the shutter in consideration of this. On the other hand, in the configuration shown in FIG. 12, since the end surface 62 of the slide shutter (front) 61a is arranged at the same height as the end surface 63 of the slide shutter (rear) 61, the photosensitive drum 11
The position of the width blank exposure end face irradiated to the top is symmetrical, and the shutter position control becomes easy.

In the present invention, the number of slide shutters may be plural, but if the number of shutters is two, it becomes larger than half of the image width even if the shutters are completely overlapped (two shutters make the entire image width. Even when the cover is covered, it is necessary to make an overlapping part in the central part of the two shutters to prevent exposure leakage, and then the length of one shutter becomes larger than half the image width). In order to correspond to half, it is necessary to stack two shutters and move the entire two shutters. Setting the number of shutters to three as in the present embodiment is a function of the device and simplification of the device. It is preferable from the viewpoint of chemical conversion.

Of course, a plurality of shutters may be provided between the individually driven shutters.

[0044]

As described above, according to the present invention, since the shutter for blank exposure is slidable in the direction orthogonal to the moving direction of the photoconductor in the apparatus in which the light source for pre-exposure and the light source for blank exposure are made common, It is possible to cope with various copying magnifications and various types of image composition without complicating the apparatus.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an image forming apparatus that is an embodiment of the present invention.

FIG. 2 is a diagram showing an exposure unit of this embodiment.

FIG. 3 is a diagram showing slits of an exposure unit.

FIG. 4 is a diagram showing a slide shutter of an exposure unit.

FIG. 5 is a view of the slide shutter as viewed from the C direction.

FIG. 6 is a control block diagram relating to a slide shutter.

FIG. 7 is a diagram showing a wire mounting portion that drives a slide shutter.

FIG. 8 is a diagram showing a relationship between a flag of a slide shutter and a sensor.

FIG. 9 is a diagram showing how to move a slide shutter.

FIG. 10 is a diagram showing a relationship between a slide shutter and an image formed.

FIG. 11 is a diagram illustrating an arrangement of images formed on a recording sheet.

FIG. 12 is a diagram showing a slide shutter of another embodiment of the present invention.

[Explanation of symbols]

 11 Photoreceptor 12 Charger 17 Exposure Means 22a Slide Shutter (Front) 22b Slide Shutter (Middle) 22c Slide Shutter (Rear) 25 Light Source (Common)

Claims (2)

[Claims] 1. A movable photoconductor, charging means for charging the photoconductor, and pre-exposure means for exposing the photoconductor upstream of the charging means in the moving direction of the photoconductor.
First and second blank exposing means for exposing a non-image portion of the photosensitive body on the downstream side of the charging means in the moving direction of the photosensitive body, the pre-exposure means, the first blank exposing means. And the light source used in the second blank exposing means is common, and the first blank exposing means exposes the non-image portion formed at the end portion of the image portion in the moving direction of the photoconductor, and the second blank exposing means. In the image forming apparatus, the exposing means exposes a non-image portion formed at an end portion of the image portion in a direction orthogonal to the moving direction of the photoreceptor, and the second blank exposing means changes the exposure width of the photoreceptor. An image forming apparatus comprising: a light shielding unit movable in a direction orthogonal to a moving direction. 2. The light shielding means has a plurality of light shielding members,
The image forming apparatus according to claim 1, wherein the light shielding members at both ends are independently driven.