JPH08143180A - Image forming device - Google Patents

Abstract

PURPOSE: To provide an image forming device which is constituted to reliably form an image on the blank surface of a paper sheet without a troublesome work, such as arrangement and assortment of paper sheets, even when used paper sheets are used. CONSTITUTION: A scanner 32 is provided to detect the presence of an image on the surface to be image-formed of a used copy paper fed from a feed paper cassette 48 by a paper feeding mechanism. When an image on the surface to be image-formed is detected by the scanner, image forming operation of an image forming part 6 is stopped and after a copy paper is turned over by a turn-over mechanism 64, the paper is re-fed to the image forming part.

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, and more particularly to
The present invention relates to an image forming apparatus capable of forming an image using used paper.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for cost saving and resource saving by reuse. Therefore, even in an image forming apparatus, for example, an electrophotographic copying machine, in order to meet such a demand, the back side of copied copy paper, that is, an unused blank surface is reused for copying. Has been.

When the copied copy paper is reused,
A large number of copied copy sheets are sorted and arranged by the operator so that the unused surfaces do not mix in the top and bottom, that is, the unused surfaces are all facing in one direction. After the paper is taken out, it is loaded into the paper feed cassette of the copying machine.

Then, the loaded copy sheets are taken out one by one from the paper feed cassette, and the desired image is copied on the unused surface of the copy sheet in the image forming section. As a result, it is possible to effectively use the copy paper and save resources and reduce costs.

[0005]

However, when a large number of copied copy sheets are manually arranged and sorted, there is a problem that the work is complicated and takes a lot of time. Furthermore, there is a possibility that copy paper sheets with different orientations and copy paper sheets with double-sided copy may be mistakenly mixed. In this case, the image is copied over the copy surface of the copy paper, and the copy needs to be taken again.

The present invention has been made in view of the above points, and an object thereof is to use used paper even if it is used.
An object of the present invention is to provide an image forming apparatus capable of surely forming an image without troublesome work such as organizing and sorting sheets.

[0007]

In order to achieve the above object, an image forming apparatus according to claim 1 of the present invention comprises an image forming means for forming a desired image on an image forming surface of a sheet.
Paper feeding means for feeding paper through the image forming means,
Detection means for detecting the presence / absence of an image on the image forming surface of the paper fed by the paper feeding means; and, when the image on the image forming surface is detected by the detecting means, Stop means for stopping the image forming operation by the image forming means.

An image forming apparatus according to a fourth aspect of the present invention includes an image forming means for forming a desired image on the image forming surface of the paper, and a paper feeding means for feeding the paper through the image forming means. Detecting means for detecting the presence or absence of an image on the image forming surface of the paper fed by the paper feeding means; and the image forming surface when the image on the image forming surface is detected by the detecting means. When the image on the image forming surface is detected by the detecting means and the stopping means for stopping the image forming operation by the image forming means, the sheet having passed through the image forming means is reversed to the image forming means. Refeeding means for refeeding.

An image forming apparatus according to a fifth aspect of the present invention includes an image forming means for forming a desired image on an image forming surface of a sheet, a sheet feeding means for feeding the sheet through the image forming means, and First detecting means for detecting the presence / absence of an image on the image forming surface of the paper fed by the paper feeding means; and when the image on the image forming surface is detected by the first detecting means, When an image on the image forming surface is detected by the first detecting means, it has a stopping means for stopping the image forming operation by the image forming means on the image forming surface, and a stacking portion capable of stacking sheets. A re-feeding unit for reversing the sheet that has passed through the image forming unit and re-feeding the sheet to the image forming unit; and detecting the presence or absence of an image on the back surface of the sheet fed by the re-feeding unit. 2 detection means, and the second When the image on the back surface is not detected by the output means, the operation of the stopped image forming means is restarted, and when the image on the back surface is detected, the stopped state of the image forming means is maintained and the paper is loaded. And a control unit for stacking the sheet in the stacking unit by the sheet re-feeding unit.

[0010]

According to the image forming apparatus of the first aspect of the present invention configured as described above, when the used paper is reused to form an image, the used paper fed by the paper feeding means is First, the presence or absence of an image on the image formation surface is detected by the detection means. Then, when no image is detected, that is, when it is detected that the image forming surface is blank, the sheet is sent to the image forming unit as it is, and a desired image is formed on the image forming surface. .

On the other hand, when the detecting means detects an image on the image forming surface of the sheet, that is, when it is detected that the image forming surface is not a blank sheet but already used, the stopping means causes the image forming surface to be covered. The image forming operation of the image forming unit on the image forming surface is stopped. Therefore, the image is not formed on the used surface of the fed paper by the image forming unit.

According to the image forming apparatus of the fourth aspect, when the used paper is reused to form an image, the used paper fed by the paper feeding means is first detected by the detecting means. Presence or absence of an image on the image forming surface is detected. When it is detected that the image forming surface is blank, the sheet is sent to the image forming means as it is, and a desired image is formed on the image forming surface.

On the other hand, when the detecting means detects the image on the image forming surface of the sheet, the stopping means stops the image forming operation of the image forming means on the image forming surface.
Then, the sheet passes through the image forming unit, is reversed by the sheet re-feeding unit, and is sent to the image forming unit again. As a result, the used paper is automatically inverted and a document image is formed on the back surface thereof.

According to the image forming apparatus of the fifth aspect, when the used sheet is reused to form an image, the used sheet fed by the sheet feeding means is first detected. The means detects the presence or absence of an image on the image formation surface. When it is detected that the image forming surface is blank, the sheet is sent to the image forming means as it is, and a desired image is formed on the image forming surface.

On the other hand, when the image on the image forming surface of the sheet is detected by the first detecting means, the stopping means stops the image forming operation of the image forming means on the image forming surface. Then, the sheet passes through the image forming unit, is reversed by the sheet re-feeding unit, and is sent to the image forming unit again. Then, the presence / absence of an image on the image-formed surface (rear surface) of the reversed sheet is detected by the second detection unit. Then, when it is detected that the image forming surface is blank, the control means restarts the operation of the image forming means, the paper is sent to the image forming means as it is, and the desired image is formed on the image forming surface. Is formed.

When the image on the image forming surface of the sheet is detected by the second detecting means, that is, when both the front and back sides of the sheet have been used, the image forming means is maintained in the stopped state and re-charged. It is accumulated in the accumulating section by the paper means.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic digital copying machine will be described in detail below with reference to the drawings. As shown in FIG. 1, the digital copying machine includes an apparatus main body 10, and an image reading unit 4 functioning as a reading unit and an image forming unit 6 functioning as an image forming unit are provided in the apparatus main body 10. ing.

The image reading section 4 is disposed on the upper surface of the apparatus main body 10, and is an original placing table 12 made of transparent glass on which an object to be read, that is, an original D is placed, and the original placing table 12
A size plate 12a that is disposed at one end of the sheet and indicates the position where the document D should be placed.

On the upper surface of the apparatus main body 10, a document placing table 12 is provided.
Automatic document feeder 80 (hereinafter,
ADF). The ADF 80 is arranged so as to be openable and closable with respect to the document placing table 12, and also functions as a document retainer that brings the document D placed on the document placing table 12 into close contact with the document placing table 12.

The ADF 80 is a document tray 82 on which a document D is placed, and an empty sensor 8 for detecting the presence or absence of a document.
1, a pickup roller 83 for taking out the originals one by one from the original tray 82, a paper feed roller 84 for conveying the taken out originals, an aligning roller pair 85 for aligning the leading edge of the originals, and an upstream side of the aligning roller pair. An aligning sensor 86 for detecting the arrival of the document and a size sensor 87 for detecting the size of the document D are provided.

Further, the ADF 80 is provided with a conveyor belt 88 arranged so as to cover almost the entire document placing table 12.
The document D fed from the size plate 12a side to the document placing table 12 by the sheet feeding roller 84 and the aligning roller pair 85 is sent to a predetermined position on the document placing table by the conveyance belt 88 and positioned.

In the ADF 80, a reversing roller 90, a non-reversing sensor 93, a flapper 91, and a paper discharge roller 92 are arranged at the end opposite to the aligning roller pair 85 with the conveyor belt 88 interposed therebetween. After the image data of the document D is read by the document reading unit 4 of the apparatus body 10,
The document D is sent out from the document placing table 12 by the conveyor belt 88, and is discharged onto the document discharging unit 94 on the upper surface of the ADF 80 via the reversing roller 90, the flapper 91, and the discharging roller 92.

When reading the back side of the document D, the flapper 9
The original D conveyed by the conveyor belt 88 by switching 1 is reversed by the reversing roller 90, and then conveyed again to a predetermined position on the original placing table 12 by the conveyor belt 88.

The image reading section 4 provided in the apparatus main body 10 deflects the reflected light from the illumination lamp 14 and the illumination lamp 14 for illuminating the original document D placed on the original document table 12 in a predetermined direction. There is one mirror 15, and the illumination lamp and the first mirror are attached to a first carriage 16 arranged below the document table 12 in the apparatus main body 10. Further, a size sensor 17 for detecting the size of the original document placed on the original document table 12 is attached on the first carriage 16.

The first carriage 16 is the original table 12
It is arranged so as to be movable in parallel with, and is moved in parallel along the document placing table by a drive motor via a toothed belt (not shown). Further, below the document placing table 12, a second carriage 18 which is movable in parallel with the document placing table is arranged.

On the second carriage 18, second and third mirrors 20 and 21 for sequentially deflecting the reflected light from the document D deflected by the first mirror 15 are mounted at right angles to each other. The second carriage 18 uses a toothed belt or the like that drives the first carriage 16 so that the first carriage 16
The carriage 16 is driven by the carriage 16 and is moved parallel to the first carriage along the document table 12 at a speed of 1/2.

Below the document table 12, an imaging lens 22 that focuses the reflected light from the third mirror 21 on the second carriage 18 and the reflected light that is focused by this imaging lens are provided. A CCD sensor 24 that receives light and performs photoelectric conversion is provided. The imaging lens 22 is the third mirror 2
It is movably arranged in a plane including the optical axis of the light deflected by 1 through a driving mechanism, and by moving itself, the reflected light is imaged at a desired magnification. And the CCD sensor 24
Photoelectrically converts the incident reflected light and outputs an output signal as an electric signal corresponding to the read document D to a signal conversion unit (not shown).

On the other hand, the image forming section 6 is provided with a laser exposure device 26 which functions as an exposure means. The laser exposure device 26 has a semiconductor laser 27 as a light source, a polarization device 30, and an optical device 28. The optical device 28 emits a laser light according to the image data of the document D read by the image reading unit 4. The intensity of the laser beam emitted from 27 is changed and is directed to a photosensitive drum as an image carrier described later.

The image forming section 6 also has a rotatable photosensitive drum 36 as an image carrier disposed substantially in the center of the apparatus main body 10, and the surface of the photosensitive drum 36 from the laser exposure device 26. The desired electrostatic latent image is formed by exposure with laser light.

Around the photosensitive drum 36, a charging charger 37 as a charging means for charging the surface of the drum to a predetermined charge, and a toner as a developer for the electrostatic latent image formed on the surface of the photosensitive drum are supplied. And a developing device 38 for developing the image with a desired image density, and a peeling charger 39 for separating the transfer material fed from a paper cassette described later, that is, the copy paper P from the photoconductor drum. A transfer charger 40 as a transfer unit for transferring the toner image formed on the body drum to the sheet P, a peeling claw 42 for peeling the copy sheet from the surface of the photoconductor drum, and a cleaning device 44 for cleaning the toner remaining on the surface of the photoconductor drum. ,and,
A static eliminator 45 for eliminating static electricity on the surface of the photosensitive drum is arranged in order.

On the right side of the image reading section 4 in the apparatus main body 10, there are a toner hopper 71 containing toner as a developer and a toner conveying auger unit 72 for supplying toner from the toner hopper to the developing device 38. It is provided.

An upper cassette 48, a middle cassette 49, and a lower cassette 50, which can be pulled out from the apparatus body, are arranged in a laminated state at the lower part of the apparatus body 10. The upper cassette 48, the middle cassette 49, and the lower cassette 50 each have an A4 size (A4-size) placed horizontally.
R) copy paper, B4 size copy paper and A3
About 500 copy sheets of each size are stored.

A large-capacity feeder 51 is provided on the side of these cassettes, and this large-capacity feeder stores about 3000 sheets of frequently used copy paper, for example, A4 size copy paper. .

In the apparatus main body 10, a conveying path 5 extending from each cassette and the large-capacity feeder 51 through a transfer portion located between the photosensitive drum 36 and the transfer charger 40.
2 is formed, and the fixing device 53 is provided at the end of the conveying path. A discharge port 54 is formed on the side wall of the apparatus main body 10 facing the fixing device 53.

Pickup rollers 56 are provided near the upper cassette 48, the middle cassette 49, the lower cassette 50, and near the large-capacity feeder 51, respectively, to take out sheets one by one from the cassette or the large-capacity feeder. The transport path 52 is provided with a large number of paper feed roller pairs 57 that transport the copy paper P taken out by the pickup roller 56 through the transport path 52.

A registration roller pair 58 is provided on the upstream side of the photosensitive drum 36 in the transport path 52. The registration roller pair 58 corrects the inclination of the taken-out copy paper P, aligns the leading edge of the toner image on the photosensitive drum 36 with the leading edge of the copy paper P, and is the same as the moving speed of the outer peripheral surface of the photosensitive drum. The copy paper P is fed to the transfer unit at a speed. A pre-aligning sensor 59 for detecting the arrival of the copy paper P is provided in front of the registration roller pair 58, that is, on the paper feed roller 57 side.

The copy sheets P taken out one by one from each cassette or the large-capacity feeder 51 by the pickup roller 56 are sent to the registration roller pair 58 by the paper feed roller pair 57. Then, the copy paper P is sent to the transfer unit after the front end of the copy paper P is aligned by the pair of registration rollers 58. At the transfer portion, the developer image formed on the photosensitive drum 36, that is, the toner image is transferred to the transfer charger 4
0 is transferred onto the paper P.

The copy sheet P on which the toner image has been transferred is subjected to AC corona discharge from the peeling charger 39 and the peeling claw 4.
It is separated from the surface of the photoconductor drum 36 by the action of 2 and is conveyed to the fixing device 53 via the conveyor belt 60 which constitutes a part of the conveyance path 52. Then, after the developer image is melted and fixed on the copy paper P by the fixing device 53, the copy paper P is discharged onto the paper discharge tray 55 through the discharge port 54 by the paper feed roller pair 61 and the paper discharge roller pair 62. .

A first scanner 32 which functions as a first detecting means is provided on the downstream side of the pair of registration rollers 58 in the conveying path 52. First scanner 3
Reference numeral 2 has a CCD formed in a line and a line light source provided adjacent to the CCD. Then, as will be described later, when the used copy paper is used for copying, the first scanner 32 causes the cassettes 48, 49,
The presence or absence of an image on the image forming surface of the copy sheet sent from 50 or the large-capacity feeder 51, that is, the surface to which the image is transferred by the image forming unit 6 is detected.

As described above, the upper cassette 48, the middle cassette 49, the lower cassette 50, the large-capacity feeder 51, the pickup roller 56, the paper feed roller pair 57, the aligning roller pair 58, and the conveyance path 52 are the paper feed in the present invention. A sheet feeding mechanism 95 that functions as a unit is configured.

On the large-capacity feeder 51, a manual insertion port 73 is formed on the side wall of the apparatus main body 10, and the manual insertion guide 7 is directed from the manual insertion port toward the registration roller pair 58.
4 is extended. In the vicinity of the manual feed guide 74, a manual feed pickup roller 75 that conveys the copy paper inserted from the manual feed port 73 to a predetermined position, and a pair of paper feed rollers 76 that conveys the copy paper to the registration roller pair 58.
Is provided.

Below the transport path 52, the copy sheet P that has passed through the fixing device 53 is reversed and the registration roller pair 5 is again provided.
A reversing mechanism 64 is provided as a sheet re-feeding unit that feeds the sheet to the sheet feeding device 8. The reversing mechanism 64 reverses the copy sheet P that has branched from the transport path 52 and passed through the fixing device 53 and the temporary stacking section 65 that temporarily stacks the copy sheet P and temporarily stacks the sheet 65.
To the registration roller pair 58, a pickup roller 67 for picking up the copy sheets P stacked in the temporary stacking unit one by one, a feed roller 69 for feeding the picked-up sheets to the registration roller pair 58 through the transport path 68, Is equipped with. A distribution gate 70 that selectively distributes the copy paper P to the discharge port 54 or the reversal path 66 is provided at a branch portion between the transport path 52 and the reversal path 66.

When performing double-sided copying, the copy paper P that has passed through the fixing device 53 is guided to a reversing path 66 by a sorting gate 70, temporarily accumulated in a reversed state in a temporary accumulating section 65, and then picked up. It is sent to the registration roller pair 58 through the transport path 68 by the roller 67 and the paper feed roller pair 69. Then, the copy paper P is aligned by the registration roller pair 58, and then sent to the transfer portion again, and the toner image is transferred to the back surface of the copy paper P. After that, the copy paper P is discharged onto the paper discharge tray 55 via the conveyance path 52, the fixing device 53, and the paper discharge roller 62.

A second scanner 33 functioning as a second detecting means is provided at the end of the inversion path 66. Like the first scanner 32, the second scanner 33 has a CCD and a light source. When the used copy paper is used for copying, as described below, the second scanner 33 reverses the copy paper sent to the temporary stacking unit 65 via the inversion path 66, that is, reverses the copy paper. The surface to be an image formation surface later is scanned to detect the presence or absence of an image.

As shown in FIG. 1, the digital copying machine has a sorter 20 for arbitrarily sorting and stacking a large number of copied copy sheets discharged from the discharge port 54 of the apparatus body 10.
It has 0.

The sorter 200 is connected to the discharge port 54 and is arranged in the apparatus main body 10 side by side.
Have two. The side surface of the housing 202 located on the opposite side of the apparatus body 10 has an opening 203. Also, the housing 2
A tray unit 204 that can move up and down along the vertical direction is provided in the unit 02. The tray unit 204 is
A large number of trays for accumulating copy sheets discharged from the apparatus body 10 are attached in a stacked state along the vertical direction.

These trays are the non-sort tray 205 located at the top and a large number of sorting trays 20 stacked below the non-sort tray with a predetermined gap.
Includes 6. The non-sort tray 205 and the sorting tray 206 extend out of the housing 202 through the opening 203.

Further, in the housing 202, there are a feed roller pair 208 and a discharge port 54 which are provided so as to face the discharge port 54 and discharge the copy paper sent by the discharge roller pair 62 onto the non-sort tray 206. A flapper 210 located between the feed roller pair 208, a guide roller 224 provided adjacent to the flapper 210, and a paper sensor 222 located between the discharge port and the flapper for detecting arrival of copy paper.
Is provided.

The flapper 210 has a discharge position for guiding the copy paper sent from the paper discharge roller 62 to the feed roller pair 208, and a sorting position for guiding the copy paper sent from the paper discharge roller 62 to the sorting tray 206 side. Is provided so as to be rotatable, and a solenoid (not shown) can be used to switch between the two positions.

In the casing 202, the guide roller 22
4, a sorting roller 226 is disposed below the guide roller 226. Between the guide roller and the sorting roller, a guide 228 that guides the copy sheet directed downward by the flapper 210 to the sorting roller 226 and the arrival of the copy sheet are detected. And a paper sensor 228 for controlling the sheet.

Further, the sorter 200 is provided with each sort tray 2
Reference staple position of copy sheets accumulated on 06,
In other words, the stapler 236 is provided for stippling one corner of the copy sheets stacked on the tray on the side of the copying machine body 10.

According to the sorter 200 having the above structure, when the flapper 210 is switched to the sorting position,
Copy paper P discharged from the discharge port 54 of the apparatus main body 10
Is sent to the sorting roller 226 by the flapper 210, the guide roller 224 and the guide 228. And
The copy sheet P is discharged by the sorting roller 226 onto the sort tray 206 located opposite to these sorting rollers. Therefore, by driving the tray unit 204 up and down by an elevator motor (not shown), the copy sheets P can be sequentially discharged and sorted on the sort tray 206 facing the sorting roller 226.

FIG. 2 schematically shows the configuration of the control system and drive system of the copying machine configured as described above.
As can be seen from this figure, the control system includes a main control unit 100 that controls the operation of the entire copying machine. The main control unit includes the image forming unit 6, the paper feeding mechanism 95, the reversing mechanism 64, and various copying machines. The operation panel 78 for setting the operation mode of No. 1 and the image processing circuit 102 for processing the image data sent from the image image reading unit 4 are connected.

Further, the main control unit 100 stores a ROM 104 in which a control program and the like are stored, a RAM 106 for storing numerical data such as the number of copies and a copy magnification input from the operation panel 78 and performing arithmetic processing, and an image reading. A page memory 108 for temporarily storing image data read by the unit 4, image data read by the first and second scanners 32 and 33, or image data input from an external device (not shown) is connected. . The main control unit 100 constitutes stop means, regulation means and control means in the present invention.

The image forming section 6 drives the high voltage transformers 110 and 112 for applying a predetermined voltage to the charging charger 37 and the transfer charger 40, the high voltage transformer 114 for applying a developing bias to the developing device 38, and the developing device. And a drive unit 116. High voltage transformer 110, 1
12, 114 are controlled by the power supply control unit 118 under the control of the main control unit 100. Further, the photoconductor drum 36 and the fixing device 53 of the image forming unit 6 are controlled by the main control unit 100, and the drum driving unit 120 and the fixing driving unit 122.
Driven by each.

The first and second scanners 32 and 33 are
The operation is controlled by the main control unit 100, and the read image data is input to the main control unit. Furthermore, the main controller 1
A sub-control unit 124 that controls the operations of the image reading unit 4 and the ADF 80, and a sorter control unit 126 that controls the operations of the sorter 200 are connected to 00 via interfaces 128 and 130, respectively.

Next, the operation of the digital copying machine configured as described above will be described. Here, a case where a document is copied using used copy paper will be described according to the flowchart shown in FIG.

In this case, used copy paper, for example,
For example, it is assumed that the copy paper of A4 is loaded in the upper cassette 48, and that the blank surface of the copy paper is not sorted and arranged.

In copying, first, the A4 original is set at a predetermined position on the original placing table 12, the used paper use mode is set and the paper size A4-R is selected by the operation panel 78, and then the copy is performed. Press the start key.

Then, the image reading section 4 reads an image from the original on the original table 12, and the image data of the read original is stored in the page memory 108 via the main control section 100. On the other hand, at the same time when the document is read, the paper feed mechanism 94 is operated, and the pick-up roller 56 takes out one used copy sheet from the upper cassette 48. The copy paper taken out is sent by the paper feed roller pair 57 to the registration roller pair 58 through the conveyance path 52, and the leading end of the copy paper is aligned by the registration roller pair 58.

Further, the copy paper is a registration roller pair 58.
Image forming surface of the copy paper, that is,
The surface of the document on which the image is copied is scanned by the first scanner 32, and the image data is read. The image data of the read copy paper is stored in the page memory 108 via the main control unit 100. Then, the main control unit 100 determines whether or not there is an image on the image forming surface of the copy sheet, that is, whether the image forming surface is a blank sheet, based on the stored image data of the copy sheet.

When the image data is equal to or lower than the predetermined national level, that is, the image forming surface is blank, the main control unit 100 operates the image forming unit 6 to execute the image forming operation. That is, in the image forming operation, the laser exposure device 26 exposes the photosensitive drum 36 based on the image data of the document stored in the page memory 108 to form an electrostatic latent image, and the electrostatic latent image is developed by the developing device. Developed by 38. Further, the aligning roller pair 58 is driven in synchronization with the image forming operation, and the copy sheet is conveyed through the photosensitive drum 36. As a result, the toner image on the photoconductor drum 36 is transferred to the image forming surface of the copy paper, that is, the blank paper surface.
Then, the copy sheet passes through the fixing device 53, where the toner image is fixed, and then the sorter 200 is discharged through the discharge port 54.
The sheets are ejected onto the non-sort tray 205.

On the other hand, when the image data read from the copy paper by the first scanner 32 is not below the predetermined national level, that is, when it is determined that the image forming surface of the copy paper is not a blank paper, the main control is performed. The unit 100 stops the image forming operation, drives the aligning roller pair 58 of the paper feeding mechanism 94 to feed the copy paper, and simultaneously operates the reversing mechanism 64. As a result, the copy sheets are guided to the reversing path 66 after passing through the photoconductor drum 36, and are stacked in the temporary stacking unit 65 in a state where the front and back are reversed.

Copy paper is fed from the reversing path 66 to the temporary stacking unit 6
While being fed to 5, the back surface of the copy paper, that is, the surface to be the image formation surface after being reversed is scanned by the second scanner 33, and the image data is read. The read image data on the back surface of the copy sheet is stored in the page memory 108 via the main control unit 100. Then, the main control unit 100 determines, based on the stored image data of the copy paper, whether or not there is an image on the image formation surface (back surface) of the copy paper, that is, whether the image formation surface is blank. To do.

When the image data is below the predetermined national level, that is, when it is determined that the image forming surface is blank, the main control unit 100 operates the reversing mechanism 64 and the pickup roller 67 causes the temporary stacking unit 65 to transfer the image. The inverted copy paper is taken out and sent by the paper feed roller 69 to the aligning roller pair 58. Then, the main controller 100
Performs the image forming operation by operating the image forming unit 6, and conveys the copy sheet by the aligning roller pair 58 in synchronization with the image forming operation. As a result, the toner image corresponding to the image data of the original is transferred to the back surface of the copy sheet, that is, the image forming surface, and then the copy sheet passes through the fixing device 53 and then is placed on the non-sort tray 205 of the sorter 200. The paper is ejected.

When the image data read from the copy paper by the second scanner 32 is not below the predetermined national level, that is, when it is determined that the front and back sides of the copy paper are not blank, the main controller 100 Keeps the image forming operation of the image forming unit 6 in a stopped state and stops the operation of the reversing mechanism 64. As a result, the copy sheets are stacked in the temporary stacking unit as they are without being taken out from the temporary stacking unit 65. Instead, the main controller 100 operates the paper feed mechanism 94 to feed the next copy paper from the upper cassette 48, and again executes the same operation as above. Then, when the image of the original is normally copied onto the blank surface of the copy sheet, the copying operation is finished.

According to the digital copying machine configured as described above, when copying is performed using the used copy paper, an image is already formed on the image forming surface of the fed copy paper and a blank surface is formed. If not, image formation by the image forming unit 6 is not performed. Therefore, it is possible to prevent the original image from being erroneously copied onto the copied surface of the copy sheet.

If the image forming surface of the copy sheet is not a blank sheet, the copy sheet is automatically inverted by the inversion mechanism and then sent to the image forming section 6 again. Then, a desired original image is copied on the back side of the blank sheet of copy paper.

Further, when the front and back sides of the copy sheet are both used and not blank, the copy sheet is accumulated in the temporary accumulating section 65 of the reversing mechanism 64 and is not used for copying. Therefore, according to the digital copying machine having the above configuration, when used copy paper is used, even if a large number of used copy papers are loaded in a state in which the front and back are not arranged, the front and back are already used. Even when used copy sheets are mixed, the original image can be surely copied on the blank side of the copy sheet.

Therefore, when a large number of used copy sheets are loaded into the copying machine, it is not necessary to manually sort and arrange these copy sheets, and the operation becomes easy. Also,
Since the original image is not accidentally overlaid on the used surface of the copy paper, a troublesome operation such as re-copying is unnecessary, and operability is improved. as a result,
The used copy paper can be easily reused, and the cost and resources can be saved.

Further, since the used copy sheets on both the front and back sides are accumulated in the temporary stacking section, they can be discarded when a certain amount of copy sheets are stacked in this temporary stacking section. Therefore, it is not necessary to discard this double-sided used copy paper every time it is generated, and the operability is further improved.

In the above embodiment, the used copy paper may be loaded in the middle cassette 49 or the lower cassette 50 instead of the upper cassette 48, and the size thereof may be other than A4. It is also possible to load used copy paper into the large-capacity feeder 51 and use it, but in this case, the first scanner 3 is used.
2 is provided near the aligning roller pair 58.

In the above embodiment, the case where the originals are manually set one by one on the original placing table has been described.
The ADF 80 may be used to automatically set a large number of documents on the document table.

The present invention is not limited to the above-described embodiments, but can be variously modified within the scope of the present invention. For example, in the above embodiment, the copying machine having the reversing mechanism has been described, but the present invention can be applied to a copying machine having no reversing mechanism. In this case, when the used copy paper is used for copying, the image forming surface of the copy paper is read by the first scanner and the image is present, that is, when the copy paper is not blank, as in the above case. This copy paper is a sorter non-sort tray 2
The sheet is discharged onto the tray 05 or a predetermined one tray 206. Then, the next copy sheet is fed.

Even with such a configuration, the original image can be surely copied onto the blank side of the used copy paper, and the used copy paper can be easily reused. Further, the present invention is not limited to the digital copying machine and may be applied to other image forming apparatuses such as a laser printer or an analog copying machine.

When the present invention is applied to an analog copying machine, it is constructed as follows. Generally, an image reading unit of an analog copying machine includes a light source that irradiates a document with light to scan it, and an exposure optical system that guides reflected light from the document to the surface of the photosensitive drum. Further, the image forming unit is shown in FIG.
The image forming section 6 shown in FIG. Then, the image data of the original read by the image forming unit, that is, the reflected light is sent to the surface of the photosensitive drum at the same time as the reading, and the image forming operation is started. for that reason,
After the image on the copy sheet is read by the first scanner 32, the electrostatic latent image is formed on the photosensitive drum 36 at the time when the copy sheet is sent to the aligning roller pair 58. Therefore, when the image forming surface of the copy sheet is not a white sheet, it is necessary to stop the image forming operation and regulate the toner image formation.

Therefore, in this case, the developing bias applied to the developing device 38 by the high voltage transformer 114 of the image forming unit 6 shown in FIG. A high value, for example, the same potential as the non-exposed portion on the surface of the photosensitive drum is controlled to prevent the electrostatic latent image on the photosensitive drum from being developed by the developing device. Then, after the copy sheet is reversed and fed, or when the next copy sheet is fed, the image of the original is read again and the above operation is repeated. As a result, it is possible to prevent the original image from being mistakenly copied on the used surface of the copy sheet, and it is possible to obtain the same effects as the above-described embodiment.

[0078]

As described above in detail, according to the image forming apparatus of the present invention, even when an image is formed by using a used sheet, the troublesome work such as organizing and sorting the sheet is performed. It is possible to reliably form an image on the blank side of the sheet without causing any trouble. Therefore, it is not necessary to manually sort the sheets and arrange them, and the troublesome operations of re-forming the image are not necessary, and the operability is improved. As a result, the used paper can be easily reused, and the cost and resources can be saved.

[Brief description of drawings]

FIG. 1 is a sectional view showing the entire digital copying machine according to an embodiment of the present invention.

FIG. 2 is a block diagram schematically showing a configuration of a control system and a drive system of the digital copying machine.

FIG. 3 is a flowchart showing an operation when copying is performed using used paper by the digital copying machine.

[Explanation of symbols]

4 ... Image reading unit, 6 ... Image forming unit, 12 ... Document placing table, 26 ... Laser exposure device, 32 ... First scanner, 3
3 ... 2nd scanner, 36 ... Photosensitive drum, 38 ... Developing device, 64 ... Reversing mechanism, 93 ... Paper feeding mechanism, 100 ... Main control part, 118 ... Power supply control part.

Claims (5)

[Claims] 1. An image forming unit for forming a desired image on an image forming surface of a sheet, a sheet feeding unit for feeding the sheet through the image forming unit, and a sheet covering unit for feeding the sheet fed by the sheet feeding unit. Detecting means for detecting the presence or absence of an image on the image forming surface, and when an image on the image forming surface is detected by the detecting means, the image forming operation by the image forming means on the image forming surface is stopped. An image forming apparatus including: a stopping unit. 2. An image forming unit for forming a desired image on an image forming surface of a sheet, a sheet feeding unit for feeding the sheet through the image forming unit, and a sheet covering unit for feeding the sheet fed by the sheet feeding unit. Detecting means for detecting the presence or absence of an image on the image forming surface, and when an image on the image forming surface is detected by the detecting means, the image forming operation by the image forming means on the image forming surface is stopped. An image forming apparatus comprising: a stopping unit; and a discharging unit that discharges the fed sheet when the image forming operation is stopped by the stopping unit. 3. An image carrier, an exposing unit for forming an electrostatic latent image on the image carrier, and a developer for supplying the developer to develop the electrostatic latent image to form a developer image. And a transfer unit for transferring the developer image onto a sheet, and an image forming unit for forming a desired image on the image forming surface of the sheet; and a sheet feeding unit for feeding the sheet through the image forming unit. Means, detection means for detecting the presence or absence of an image on the image forming surface of the paper fed by the paper feeding means, and the developing means when the image on the image forming surface is detected by the detecting means. An image forming apparatus comprising: a stop unit that controls the supply of the developer by the unit to stop the image forming operation by the image forming unit on the image forming surface. 4. An image forming unit for forming a desired image on an image forming surface of a sheet, a sheet feeding unit for feeding the sheet through the image forming unit, and a sheet covering unit for feeding the sheet fed by the sheet feeding unit. Detecting means for detecting the presence / absence of an image on the image forming surface, and when the detecting means detects an image on the image forming surface, stops the image forming operation by the image forming means on the image forming surface. Stop means, and refeeding means for reversing the sheet that has passed through the image forming means and refeeding it to the image forming means when an image on the image forming surface is detected by the detecting means. Image forming apparatus equipped. 5. An image forming unit for forming a desired image on an image forming surface of a sheet, a sheet feeding unit for feeding the sheet through the image forming unit, and a sheet covering unit for feeding the sheet fed by the sheet feeding unit. First detecting means for detecting the presence or absence of an image on the image forming surface; and when the image on the image forming surface is detected by the first detecting means, the image forming means for the image forming surface When the image on the image forming surface is detected by the first detecting unit, the image forming unit has a stopping unit for stopping the image forming operation and a stacking unit capable of stacking sheets, and the image forming unit passes through the image forming unit. Re-feeding means for reversing a sheet and re-feeding it to the image forming means; second detecting means for detecting the presence or absence of an image on the back surface of the sheet fed by the reversing means; Image on the back side by the detection means of When the image is not detected, the operation of the stopped image forming means is restarted, and when the image on the back surface is detected, the stopped state of the image forming means is maintained and the sheet is re-fed by the re-feeding means. An image forming apparatus comprising: a control unit that accumulates in an accumulation unit.