JPH07302016A - Image forming device - Google Patents

Abstract

(57) [Summary] [Purpose] Reduction of unnecessary copying after a copy interruption instruction. Efficient use of recording paper. [Constitution] Photoreceptor, charging means, exposure means, developing device, transfer means, a transport mechanism for transporting the recording paper onto which the visible image has been transferred to the paper discharge portion, and the recording paper sent to it is turned over and transferred. In the image forming apparatus, a reversing mechanism for re-conveying the reversing means to the recording medium, and a switching means for switching the reversing mechanism to a rest state for one-sided recording and a driving state for double-sided recording for transferring a visible image on the back side are being processed. And an interruption means for erasing the electrostatic latent image reaching the developing device at the time of the interruption.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatographic image forming apparatus having a double-sided recording function and / or a composite recording function, and particularly, although not intended to be limited to this, a copying machine having such a function. Regarding

[0002]

2. Description of the Related Art For example, in an electrostatographic copying machine, a photoconductor is charged and its charged surface is exposed to image light to form an electrostatic latent image, which is visualized (developed) by a toner. After transferring the visible image to the recording paper and passing the recording paper carrying the visible image through the fixing device,
Eject to the output tray. In a copying machine having a double-sided recording function or a composite recording function, the recording paper on which an image is formed on the front surface by the first image formation is retransmitted to the transfer section through the front / back reversing mechanism or the circulation / conveyance mechanism, and then the second time. Image formation is performed on the back surface or the front surface. On the other hand, there is also a copying machine provided with a document feeder (ADF) in order to perform image formation of a large number of documents at high speed.

When a document being conveyed by the ADF is jammed, that is, when a misfeed occurs, an eraser erases the electrostatic latent image on the photoconductor to apply (develop) toner on the photoconductor. A technique to avoid is presented in Japanese Patent Application No. 2-18360, and
When a document that is being conveyed by the ADF has a conveyance error such as a jam, the already-supplied paper is conveyed to the double-sided tray, and the paper stocked in the double-sided tray is re-printed when printing is performed after the document conveyance error is released. The applicant has presented the technology to be utilized and is already known. In this case, when the double-sided recording function is not provided, the already-supplied paper is stopped at the registration roller unit and reused for image recording after the original conveyance failure is released.

[0004]

[Problems to be Solved by the Invention] All of these are AD
This is performed when the F paper sensor detects a paper jam. However, some image forming apparatuses have a function of interrupting image formation in response to an interrupt key or an interrupt instruction input, and an operator instructs the interrupt. When the operator gives an instruction to suspend, the image forming apparatus completes the image forming process of the recording sheets already fed from the cassette at that time, and stops the subsequent image forming. Therefore, when viewed from the operator, an unnecessary copy (image formation after the interruption instruction) is created.

A first object of the present invention is to reduce unnecessary copying after an interruption instruction as much as possible, and a second object is to efficiently use a recording medium.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a photoreceptor, a charging means for charging the photoreceptor, an exposing means for exposing the charged photoreceptor to image light, and an electrostatic latent image formed on the photoreceptor by this exposure. A developing device for developing the image, a transfer means for transferring the developed image developed by the developing device onto a transfer medium, a transport mechanism for transporting the transfer medium on which the developed image is transferred to a paper discharge portion, and a transfer mechanism And a reversing mechanism for reversing the transfer medium and conveying it again to the transfer means, and a double-sided mechanism for transferring the visible image to the back surface by making the reversing mechanism in a rest state during single-sided recording for transferring the visible image onto the surface of the transfer medium. In an image forming apparatus provided with a switching unit that is in a driving state at the time of recording, an interrupting unit that interrupts the image forming process and an electrostatic latent image of the photoconductor reaching the developing unit at the time of the interrupting are erased. Equipped with latent image erasing means And wherein the door

[0007].

When there is an interruption, the latent image erasing means erases the electrostatic latent image on the photoconductor reaching the developing unit, so that the visible image is not transferred onto the transfer medium and the developer (toner) is used. The transfer medium in which the consumption of) is suppressed and the visible image is not transferred can be reused for the next image recording. That is, unnecessary image recording after the interruption instruction is reduced, and wasteful consumption of the recording medium is reduced.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0009]

FIG. 1 shows an embodiment of the present invention. This embodiment is a copying machine with an ADF, and as shown in FIG. 1, an ADF 2 which is a document feeding mechanism is mounted on a copying machine main body 1, and a side portion of the copying machine main body 1 is printed by size. Paper 3
The sheet feeding cassettes 4 to 6 which are sheet feeding units that store the sheets are installed.

The ADF 2 includes an original placing table 8 on which an original 7 is placed, an original detector 9, an ADF paper feed roller 10, a resist detector 11 serving as conveyance failure detecting means, and a contact glass 1.
2. The conveyor belt 13 and the like are provided. Further, the original 7 set on the contact glass 12 is provided inside the copying machine main body 1.
An exposure optical system 14 that exposes and scans the original 7 is provided. The exposure optical system 14 includes an exposure lamp 15 that illuminates the original 7 and first to third mirrors 16 to 18 that reflect the reflected light of the original 7.
And a lens 2 for forming an image of reflected light from the scanner 19 on the surface of a drum-shaped photoconductor 20.
1 and a mirror 22 and the like. Further, in the copying machine body 1, a paper feed roller 23, which is a paper transport mechanism located on the paper feed side of the paper feed cassettes 4 to 6, and a registration roller 24, which is a paper transport mechanism arranged immediately before the photoconductor 20. And are provided. Then, on the upstream side of the registration roller 24 and the downstream side of the exposure position, an erase lamp 25 having a length corresponding to the width of the photosensitive member and serving as latent image erasing means, and a developing bias are applied at the time of development. Developing device 2
6 is provided in that order, and a transfer charger 27 is provided downstream of the registration roller 24 to form an image transfer section that reaches the sheet discharge section.

Next, FIG. 2 shows a schematic configuration of a control system of the copying machine of this embodiment. First, CPU (Central Processin)
g Unit) 30, RAM (Random Access Memory) 31, R
A control section using a microcomputer including an OM (Read Only Memory) 32, input / output port buffer amplifiers 33, 34, etc. is provided, and T × D, R × of the CPU 30 is provided.
AD is achieved by serial communication between the D and CP2 terminals.
F 2 and the exposure optical system 14 are controlled. In this serial communication, when the output of PC2 is H level, ADF2 and the control section of the copying machine communicate with each other, and when the output of PC2 is L level, the exposure optical system 14 and the control section of the copying machine communicate with each other. It is configured to communicate. Here, the microcomputer of the ADF 2 performs the paper feeding / discharging process of the document 7 and the jam detection based on the data transmitted from the control unit of the copying machine. On the other hand, the microcomputer of the exposure optical system 14 uses the data transmitted from the control unit of the copying machine to
The scanner 19 and the mirror 22 are driven and controlled. In this copying machine, the CPU 30 is provided with a sheet selecting means, a sheet reusing means, a defective printing preventing means, a conveyance resuming means, and the like by firmware or the like.

The control section of the copying machine described above is based on the count value of the synchronization pulse, and is based on the count value of the synchronous pulse. The transfer sheet feed control (pulse table control A) and the document feed control (pulse table control). C) and the image forming process (pulse table control B). The synchronizing pulse is generated by the pulse oscillator 35 in synchronization with the rotation of the photoconductor 20, and is given to the CPU 30. The pulses input to the CPU 30 are counted by the counter. In addition,
As these counters, three types of counters are provided: a paper feed counter, a copy counter, and a paper feed number counter. Hereinafter, the control based on the count values of these synchronization pulses will be simply referred to as processing of pulse tables: A, B, and C.

Further, in this copying machine, as shown in FIG. 1, the printing paper 3 is turned upside down on a paper conveyance path 36 extending from the image transfer portion between the photoconductor 20 and the transfer charger 27 to the paper discharge portion. A sheet reversing mechanism that connects the sheet to the image transfer unit again is connected. Here, this paper reversing mechanism
A movable guide 37 that is rotatably supported by the paper conveyance path 36 to switch the movement direction of the printing paper 3, and the printing paper 3
Is formed by an internal cassette 38 for temporarily holding and switching back the sheet, a feed roller 39, and the like, and a printing state switching unit, a sheet sorting unit, and a sheet reusing unit for controlling the operations of these members 37 to 39 are CPU 30. It is formed of firmware.

An operation panel of the copying machine shown in FIG. 1 is shown in FIG. The operation panel is provided with a clear / stop key "50" as a copy interruption key, which is put into the CPU 30 via the key SW group "51" of the operation display section shown in FIG. 2 to clear / stop during copying. When the key "50" is pressed, the control unit is programmed to perform the process of interrupting copying.

In such a structure, the timing control of the conveyance of the original 7 and the printing paper 3 in this embodiment is
It is performed at the timing shown in FIG. That is, the original 7
After setting the print sheet 3 and the print sheet 3 and pressing the print switch, the conveyance of the first original 7 is started. When the “G” time has elapsed since the document 7 was started to be conveyed, normally the document 7 is
Has reached the position of the registration detector 11, a non-feed jam check (conveyance failure detection) of the document 7 is performed here. Further, based on the document size data and the jam detection data transmitted from the ADF 2, the printing paper 3 to be conveyed should be printed.
Is determined and the paper feed roller 23 corresponding to the determined printing paper 3 starts to rotate and any of the paper feed cassettes 4 to 6
The conveyance of the printing paper 3 is started from. The printing paper 3 is not conveyed when a jam occurs. When “I” time has elapsed since the printing paper 3 was started to be conveyed, the leading end of the printing paper 3 reaches the registration roller 24 and the paper feed roller 23
Rotation is stopped. Also, the scanner 19 is started before the “D” time when the paper feed roller 23 stops rotating, and the original 7
Exposure scanning is started and an electrostatic latent image is formed. on the other hand,
After the scanner 19 is started and "E" time has elapsed, the registration roller 24 starts to rotate and the printing paper 3 is transferred to the photoconductor 20
And the image on the photoconductor 20 is transferred to the printing paper 3.

The erase lamp 25 is used in the scanner 1
The on / off control is performed according to the movement amount of 9 to erase unnecessary charges on the photoconductor 20, that is, the electrostatic latent image formed on the non-image portion (front, rear end erase, and side erase).

Here, the processing when the clear / stop key 50 on the operation panel is pressed during copying will be described with reference to FIG. FIG. 4 shows a case in which copying is interrupted while the second printing paper 3 is being fed by the paper feed roller 23. Since the copy interruption signal in FIG. 4 is not the scanner start timing, the scanner 19 remains undriven. As a result, the erase timing does not reach the leading edge, so that all the erase lamps of the erase lamp 25 are turned on by the trailing edge erase timing transmitted from the exposure optical system 14 after the first copy of the original 7 is completed. All electrostatic latent images on 20 will be erased. Further, in this case, since the scanner 19 is not driven and the registration timing does not come by the exposure optical system 14, the copying machine main body 1 is in the copy interruption state and the printing paper 3 is at the registration roller 24 position. After confirming that, the registration roller 24 is driven.
At this time, in the copying machine of this embodiment, the movable guide 37 operates under the control of the CPU 30, and when the operation mode is single-sided printing, the printing paper 3 is conveyed and held in the internal cassette 38. When the user subsequently starts printing, the printing paper 3 in the internal cassette 38 is conveyed to the image transfer section.
When the operation mode is double-sided printing, the same processing as above is performed during single-sided printing for printing on the first side, and double-sided printing for completing printing on the first side and printing on the second side. At this time, the printing paper 3 is discharged from the copying machine main body 1.

By doing so, in this copying machine,
During single-sided printing, the image is not transferred to the printing paper 3 conveyed to the image transfer section, and the blank printing paper 3 is held in the internal cassette 38 and automatically used for the next printing. The printing paper 3 can be reused without the need for the user to store the printing paper 3 in the paper cassettes 4 to 6 again. In addition, the printing paper 3 for double-sided printing, which has completed printing on one side, is automatically
Since it is discharged from the printer, it is not necessary for the operator to select the unusable printing paper 3.

As shown in FIG. 4, even when the copy interruption signal cannot be detected before the scanner start timing, the position where the electrostatic latent image is started from the start position of the scanner 19 (that is, the original on the contact glass 12 is shown). Up to the tip position, to some extent (actually 38 to 90 mm
Since there is a distance of about 150 to 400 msec in terms of time, during the movement of the scanner 19 from the scanner start to the position where electrostatic latent image formation is started (actually,
(It may be from the scanner start position until the front end erase timing is transmitted from the exposure optical system 14). If the copy interruption signal can be detected, even if the front end erase timing is transmitted from the exposure optical system 14, the copying machine main body 1 Since the document non-feed jam is detected, it is possible to ignore the leading edge erase timing and keep the erase lamp 25 all lit.

Note that such a copy operation control is performed by the CPU.
30 does. The contents are shown in FIGS. C
First, as shown in FIG. 5, when the print switch is turned on, the PU 30 starts the document transport process of transmitting a document transport signal to the ADF 2 and the drive of the main motor, which is the drive source of the copying machine, to start the copy sequence. The control paper feed counter and copy counter are cleared. When the ADF 2 starts feeding the document and detects a document jam or misfeed, it sends an ADF jam detection OK signal to the CPU 30, and at the same time sends a document jam determination signal.

As shown in FIG. 6, when the document is not jammed, the CPU 30 turns on the count-up flag of the paper feed counter in order to perform the processing of the pulse table A shown in FIG. In the case of a document jam, document jam processing is performed. When the count-up flag of the paper feed counter is turned on, the paper feed counter processing shown in FIG. 8 is performed, and the paper feed counter is turned on each time the rotation synchronizing pulse of the photoconductor 20 generated by the pulse oscillator 35 is input to the CPU 30. Add (count up). When the paper feed counter is incremented in this way, the count value of the paper feed counter (hereinafter abbreviated as paper feed counter value) is compared with each of a plurality of set values using the pulse table A in FIG. When the value is reached, the following processing is performed.

First, when the paper feed counter value becomes "1",
A paper feed counter for counting the number of conveyed printing papers 3 is added, and when the paper feed counter value becomes "10", the paper feed roller 23 is driven to start feeding the printing papers 3. When the paper feed counter value reaches "200", the copy OK flag is turned on, the count-up flag of the copy counter is turned on by the flag processing shown in FIG. 9, and the pulse oscillator is turned on by the counter processing shown in FIG. The copy counter is incremented each time the pulse generated by the signal 35 is input to the CPU 30. Then, when the paper feed counter value reaches “250”, the paper feed roller 23 is stopped.
As a result, the feeding of the printing paper 3 is stopped. Further, the count-up flag of the paper feed counter is turned off to stop the addition of the paper feed counter. Note that the paper feed counter is restarted when the printing paper 3 is conveyed, and when the registration roller 24 is driven based on the data reception from the exposure optical system 14, as shown in FIG. Is. That is, when the registration timing signal is received, the registration roller 24 is driven and the count-up flag of the paper feed counter is turned on. When the paper feed counter value reaches "300", the next paper feed timing is determined. Therefore, first, the count value of the paper feed number counter (hereinafter abbreviated as the paper feed number counter value) is used to determine whether or not the repeat is being performed. ) Is compared with the set number of sheets, and if they are not the same, the sheet feeding counter is cleared because repeat copying is being performed, and the process of pulse table: A is performed again. If they are the same, the repeat copy has ended, so the paper feed counter is cleared in preparation for copying the next original.
The presence or absence of the original 7 on the original table 8 of the ADF 2 is checked. If there is no original 7, the copy operation is finished as it is. If there is an original 7, turn on the second original flag,
Clear the paper feed counter. Here, by turning on the second original flag, the paper feeding process for the next original is performed by the pulse table C illustrated in FIG. The printing paper 3 is conveyed to the next original at the same timing as the repeat copy of the previous original because the paper feed counter is cleared. Next, as described with reference to FIG. 10, when the paper feed counter value becomes “200”, the copy counter is added, so from the time when the paper feed counter value becomes “200”, the pulse table shown in FIG. 13: The processing of B is started, the counter value of the copy counter (hereinafter abbreviated as copy counter value) is compared with the set value, and when the numbers are the same, predetermined processing is performed. Note that the pulse table processing using the copy counter also has a pulse table: C shown in FIG. 12, but these two types of operating conditions are determined by the state of the flag of the second original document. That is, the processing of the copy counter for the first original is performed by the pulse table: B
The second original is processed only by the pulse table: C, and after waiting the original feeding time, that is, when the copy counter value reaches “50”, the copy counter is cleared and the second original is processed. The flag is turned off, and the subsequent processing of the copy counter is performed by the pulse table: B.
Further, the pulse table: B is similar to the pulse table for transport control: A, and when the copy counter becomes “300”, the repeat timing of the next copy comes. Therefore, the paper feed number counter value is compared with the set number. If the number is the same, the copy operation is terminated as it is, and if the number is not the same, the second original document flag is turned on in the pulse table: A. If the copy OK flag is on, the copy OK flag is turned off, the copy counter is cleared, and the process for the next copy is started. If the copy OK flag is off (eg, the printing paper 3 is not conveyed due to the paper end, etc.), the copying operation is ended.

Here, the pulse table shown in FIG. 13: B
, The copy counter is set to “2
At the time of "0", the presence or absence of a copy interruption signal is checked, and if there is a copy interruption signal at this stage, the scanner 19 is not started, and the post-processing is started. When the counter value reaches "100", the presence / absence of a copy interruption signal and the presence / absence of the print sheet 3 on the registration roller 24 are checked again. If the copy interruption occurs and the print sheet 3 exists on the registration roller 24, the registration The roller 24 is driven to be conveyed to the image transfer portion, the count-up flag of the paper feed counter is turned on to perform paper feed counter processing, and it is determined whether the operation mode is single-sided printing or double-sided printing, and this determination is made. According to the result, the movable guide 37 is driven to drive the printing paper 3
To determine the moving direction of. Then, after that, the above-mentioned processing for the copy counter value of "300" or later is performed.

Here, the optical system data reception processing illustrated in FIG. 11 is performed corresponding to each signal transmitted from the exposure optical system 14. Further, the signal from the exposure optical system 14 drives the scanner 19 by the scanner start process when the copy counter value in the pulse table: B becomes “20”. Sent. In the operation control as described above, when the electrostatic latent image is erased by all lighting of the erase lamp 25 due to the original jam, the developing bias is applied in the phenomenon device 26 so that the developing potential is higher than the surface potential of the photoconductor 20. By increasing the height, it becomes difficult for the toner to adhere to the surface of the photoconductor 20, and more reliable blank copy can be made.

In the embodiment of the present invention described above, the printing paper for single-sided printing is held in the paper reversing mechanism by the drive control of the printing state switching means, and the printing paper for double-sided printing is conveyed to the paper ejection unit. By providing paper sorting means,
During single-sided printing, the image is not transferred to the printing paper conveyed to the image transfer section, and the blank printing paper is held in the paper reversing mechanism. It is possible to reuse the printing paper without requiring a complicated work such as storing it again in the tray. In addition, since the printing paper for double-sided printing that has completed printing on one side is automatically ejected from the device, it is possible for the operator to perform a complicated work such as selecting reusable printing paper and unusable printing paper. It is unnecessary and waste of printing paper is prevented without requiring complicated work.

Further, by providing the paper reusing means for conveying the printing paper held in the paper reversing mechanism to the image transfer section at the start of printing after the copying is interrupted by the drive control of the paper selecting means, the paper reversing mechanism is provided. The blank printing paper held in the printer is automatically used for the next printing, so the printing paper can be reused without the need for the user to store the printing paper in the paper cassette or paper tray again. It is possible to prevent waste of printing paper without requiring complicated work.

[0027]

The latent image on the photoconductor is erased by the latent image erasing means even before the image is formed even on the printing paper already fed when the copying is interrupted.
Even if the printing paper is fed and conveyed to the transfer unit, the image is not transferred and remains as a blank paper, which can be reused and waste of the transfer paper due to miscopy can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a copying mechanism according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an outline of an electric system of the copying machine shown in FIG.

FIG. 3 is an enlarged plan view of an operation panel of the copying machine shown in FIG.

4 is a time chart showing operation timings of image forming elements of the copying machine shown in FIG.

5 is a flowchart showing a part of the control operation of the CPU 30 shown in FIG.

6 is a flowchart showing another part of the control operation of the CPU 30 shown in FIG.

7 is a flowchart showing another part of the control operation of the CPU 30 shown in FIG.

8 is a flowchart showing another part of the control operation of the CPU 30 shown in FIG.

9 is a flowchart showing another part of the control operation of the CPU 30 shown in FIG.

10 is a flowchart showing another part of the control operation of the CPU 30 shown in FIG.

FIG. 11 is a flowchart showing another part of the control operation of the CPU 30 shown in FIG.

12 is a flowchart showing another part of the control operation of the CPU 30 shown in FIG.

13 is a flowchart showing another part of the control operation of the CPU 30 shown in FIG.

[Explanation of symbols]

2: Document transport mechanism 3: Printing paper 4 to 6: Paper supply unit 7: Document 11: Transport failure detection means 14: Imaging optical system 20: Photoconductor 23, 24: Paper transport mechanism 25: Latent image erasing means 26: Developing device 30: printing state switching means, paper sorting means, paper recycling means, defective printing prevention means, conveyance restarting means 37-39: paper reversing mechanism

Claims (3)

[Claims] 1. A photoconductor, a charging means for charging the photoconductor, an exposing means for exposing the charged photoconductor to image light, a developing device for developing an electrostatic latent image formed on the photoconductor by this exposure, and a developing device for developing the electrostatic latent image. Transferring means for transferring the developed image developed by a container to a transfer medium, a transport mechanism for transporting the transfer medium on which the visualized image is transferred to a paper discharge section, and the transfer medium sent to the transport mechanism is turned upside down. A reversing mechanism that conveys the reversing means to the transfer means again, and a switching mechanism that switches the reversing mechanism to a rest state during one-sided recording for transferring a visible image onto the surface of the transfer medium and a driving state during double-sided recording for transferring a visible image on the back side In the image forming apparatus including the means, an interrupting means for interrupting the image forming process, and a latent image erasing means for erasing the electrostatic latent image of the photoreceptor reaching the developing device at the time of the interruption are provided. Characteristic image formation Location. 2. A sorting method in which a recording medium for single-sided recording is held in the reversing mechanism and a recording medium for double-sided recording is conveyed to the paper discharge unit by driving the latent image erasing unit and driving control of the switching unit. The image forming apparatus according to claim 1, further comprising means. 3. The image forming apparatus according to claim 2, further comprising a reuse unit that conveys the recording medium held in the reversing mechanism to the transfer unit at the start of image formation after interruption by drive control of the selecting unit.