JPS62163039A - Image forming device - Google Patents

Abstract

PURPOSE:To select optionally the direction of a head of a formed image by forming the image by forward and backward scanning based on the reciprocation of a reciprocating member for exposing and scanning an original. CONSTITUTION:An image is formed by an image forming means at the forward and backward movement of the reciprocating means. When the latent image of an original is formed on a photosensitive drum 20 by backscanning an optical system based on the back end of the original, a copied image is obtained as the mirror image of the original. When a mirror image mode switch arranged on an operation display part DP is turned on, the copying machine is turned to a mirror image mode and the original is scanned by the reciprocation of the optical system to obtain the mirror image copy of the original image. To interrupt the formation of the mirror image based on backscanning, a mirror is rotated in the clockwise direction, the reflected light from the original is reflected by a mirror 8' and the latent image is formed on the drum 20 by the reflected light from the mirror 8'. Consequently, a normal original copying image can be obtained.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to an image forming apparatus.

[Prior art]

Conventionally, in this type of device, for example, a copying machine with a double-sided copying function, in the case of single-sided copying, the copy paper is first placed in an intermediate tray in order to align the edges of the images formed on the front and back sides of the copy paper. When doing so, I had to flip the copy paper over. This is a copy of the kasuri pattern on the reverse side.
The drawback was that the structure of the copying machine became complicated without any problems.

〔the purpose〕

An object of the present invention is to eliminate the drawbacks of the above-mentioned conventional example, and also to change the direction of the image tip of the formed image, and to form an image by scanning the document by forward movement of a reciprocating member that exposes and scans the document, and by scanning the document by backward movement. An object of the present invention is to provide an image forming apparatus that can perform the following steps.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of a tabletop automatic double-sided copying machine.

The functions of a copying machine can be roughly divided into four blocks: a paper feeding system, an exposure system, an image forming system, and a control system.

The movement of the machine will be explained based on FIG. First, when copying, the operator opens the original platen cover 1 and sets the original (original). From the operation part (not shown),
When reducing or enlarging the image, set the scaling factor as necessary using the scaling key.

In addition, the number of copies, auto density, manual selection,
Select the copy mode, single-sided or double-sided, using the respective keys.

Here, we will proceed with the discussion using an example of double-sided copying. When duplex mode is selected and the copy start key is turned on, the halogen lamp 3 turns on, the photosensitive drum 2o rotates, and the copy start key turns on.
The charged corona of is energized. The halogen lamp 3 and the first mirror have the same structure, and the document surface is scanned and the image passes through the first mirror 4, second mirror 5, third mirror 6, and zoom lens 1]. 4 mirror 7, 5th
An optical axis is formed by the mirror 8 and the sixth mirror 9, and an image is formed on the drum surface.

The image on the drum surface (latent image) is subjected to a +5 erase ramp to remove the surface potential of the area where the image is not placed, depending on the paper size. Further, in the developing section 17, the toner adheres to the area where the potential is applied, and the latent image is visualized. - Transfer paper fed from the selected cassette 22 or 24 is waiting at the registration rollers 30. The registration roller 30 rotates at a predetermined timing to align with the image on the drum surface, and the image on the drum surface is transferred to the transfer paper by the urging of the transfer corona 14.

Next, the transfer paper is separated from the drum by a paper roller 31 and conveyed to a fixing section 33 by a paper conveyance belt 32. Here, heat and pressure are applied to fuse the donor. Next, since the paper guide plate 34 is in duplex mode, it is guided to a paper discharge roller 37 and transported to a double-sided paper discharge table 38.

The paper carried here naturally slides downward due to gravity, is loaded onto rollers 39, and is stocked in the intermediate cassette 26. In addition, the paper slides down one by one so that it will not be stocked on the double-sided paper tray of 38 (.

In this way, the number of sheets whose front side has been copied is stored in the intermediate cassette. On the other hand, after the image on the drum surface has been transferred, the drum surface is cleaned in a cleaning section 19. The remaining toner adhering to the drum surface is removed. Further, 18 static eliminating lamps are irradiated to remove residual potential on the drum surface.

Next, the drum is newly charged by 13 charging coronas, and a predetermined surface potential is placed on the drum to form a new image.

Next, when one side (front side) copying is completed, the operator changes the original and performs the next copy operation (back side copying). When the original is set and a new copy start key (not shown) is turned on, the copying operation for the back side starts. At a predetermined timing, 25 paper feed rollers rotate and feed paper from 26 intermediate trays, and the paper is reversed by a guide plate 29 and added to registration rollers 30. It waits until a start signal is received at a predetermined timing to align the leading edge of the image.

The registration rollers 30 rotate at a predetermined timing to align the image edges, and the image formed on the photosensitive drum 20 is transferred. At this time, the transfer corona 14 is energized at a predetermined timing and the image is transferred to the back surface. The image is separated from the drum by a separation roller 31 and conveyed to a fixing section 33 by a conveyor belt 32. Here, the toner is fused. next·
Added to the IO roller. The kite board 34 is then guided to the paper discharge tray 36, and the transfer paper that has been copied on both sides is stored on the paper tray 36. In this way, the double-sided copying process is completed. In the case of normal single-sided copying, the guide plate guides 36 sheets to one sheet tray. Further, when copying only the back side, the paper fed from the cassette 22 or 24 is transferred to the intermediate cassette 26 in a blank state with only the paper transport system energized. At this time, the image forming system does not operate at all, and only the system that feeds paper from the paper feed cassette 22 or 24 and conveys the paper to the intermediate cassette 26 operates. In order to improve the quality of copies, an automatic exposure function is included. This controls the surface potential on the photoreceptor to a constant value, making it possible to always obtain good density regardless of the density of the original. Before the start of copying, the surface potential is first monitored.This is done by irradiating the photoreceptor 20 with light reflected by the standard reflector 10.
First, the corona voltage in step 13 is controlled to an appropriate value by monitoring it with a surface potential sensor. During a copy operation, when the user selects AUTO, the optical system performs prescanning to monitor the original, monitors the density of the original, and sets the corona voltage and bias value. 1
If the bliscan operation is troublesome because monitoring is performed every time copies are made, the value of the developing bias is controlled so that the density is at an appropriate density while successively monitoring the original density in real time. In the case of continuous copying (making multiple copies from the first original), the appropriate density can be achieved by controlling the corona voltage and lamp light intensity from the second copy. In addition, the document density detection function samples the reflected light hitting the document surface to detect the appropriate density and document size.

The tabletop automatic double-sided copy machine has been briefly explained above. ADF (document feeder) outside the main machine. A sorter or collator paper deck, charge counter, etc. may be installed around the machine.

The copying process is completed by paper feeding, charging, exposure, development, transfer, conveyance, fixing, paper ejection, and cleaning of the photoreceptor. In addition, abnormal conditions can be detected, ie, serious abnormalities include fixing temperature abnormality, abnormal lighting of exposure lamp, paper jam, and minor abnormalities such as paper empty and toner empty. In addition, a diagnosis is performed to check for any abnormalities before copying.

These are determined by sensor input and software processing. As can be easily understood from the above explanation, analog copiers are characterized by a large number of inputs and outputs and a large amount of real-time processing.

Next, the control system of this embodiment will be explained.

The control system of the analog/digital copying machine of this embodiment is composed of two controllers.

FIG. 2(a) is a diagram showing two controllers of the control system of this embodiment.

A controller 105 controls mechatronics for electrophotographic control including analog copying. A controller 106 controls an operation display section (not shown), a main drive motor, a servo motor for the document scanning system, and a pulse motor for moving the zoom lens.

FIG. 2(b) is a diagram showing the configuration of the controller 105.

Each part constituting the controller 105 will be explained based on FIG. 2(b). 105-1 is CPU],
This is an oscillator 105-1 that supplies a clock signal to 05-2.

105-2 is a CPU which is a control unit of the controller 105.
, a microcomputer and r! AM, ROM
It consists of microcomputer peripherals such as. Note that the CPU 105-2 is capable of retaining information when the power is cut off due to battery backup. Reference numeral 105-3 is a document sensor for detecting a document. 105
-5 is a temperature sensor for controlling temperature. The CPU 105-2 is an A/D for inputting the document sensor 105-3, potential sensor I6, and temperature sensor 105-5.
It has a built-in converter.

A drum encoder circuit 105-6 counts encoder pulses generated by the rotation of the drum drive motor of the copying machine and outputs TL pulses for timing control. 105-7 is a zero pulse detection unit, which detects the zero cross pulse To of the AC power supply.
o is used for the zero cross trigger of the AC power supply in the control of the count pulse for the timer, temperature, and exposure lamp.

105-9.105-1o is an I10 expansion chip.

Reference numeral 105-11 is a photosensor section, which includes various sensors such as document detection and toner detection. Controller 105
detects the original density pattern based on the detection signals from the original detection sensor 105-3 and the potential sensor 16.

In addition, the CPU 105-2 of the controller 105 is ■10
The photosensor unit 105-11, a solenoid for controlling the copying machine, a clutch, etc. are controlled via the expansion chips 105-9 and 105-10.

FIG. 2(c) is a diagram showing the configuration of the controller 106. 106-1 is an oscillator that supplies a clock to the CPU 106-2. A CPU 106-2 is a control unit of the controller 106, and is composed of a microcomputer and peripheral devices for the microcomputer such as RAM and ROM. 106-3 is a driver that drives the display section 106-4. Reference numeral 106-5 is an operation unit for operating the copying machine, and various switches on the operation unit 106-5 are used to select a mode and operate the copying machine. 106-6 is a servo motor controller that drives and controls the main motor 106-8. 106-9 is an optical encoder l that detects the movement of the main motor 106-8. A servo motor controller 106-7 drives and controls a servo motor 106-10 for an optical scanner.

106-11 is an optical encoder 2 that detects the movement of the servo motor 106-10. 106-12 is a pulse motor controller that drives and controls the pulse motor 106-13 for moving the zoom lens. The controller IO5 and the controller 106 perform normal copying operations such as paper feeding, charging, exposure, development, transfer, conveyance, fixing,
The copying process includes paper ejection and photoconductor cleaning.

In addition, the controller +05 is a photo sensor section 105-1.
Detection of abnormal conditions through sensor input from 1 and software processing, such as abnormal rise in fixing temperature as a serious abnormality.
Check for abnormal lighting of the exposure lamp, paper jams, and minor abnormalities such as empty paper and toner, and perform abnormality inspections before copying.

Mechatronic controls for copiers and other devices are characterized by a large number of inputs and outputs and a large amount of real-time processing. By applying C-MOS gate arrays, which have become popular in recent years, the number of I10 can be increased, simplifying the peripheral circuit system, reducing the overall board area, and improving reliability.

In this system, by creating a gate array around the CPU, the circuit system is simplified, the mounting area of the printed circuit board is reduced, and reliability is improved.This is the purpose of this proposal. The details of gate array formation will be omitted.

As explained in Fig. 1, when the single-sided copy set to the duplex mode is completed, the duplex paper output tray of the paper guide plate 38 (Fig.
). After being stocked on the duplex paper tray 38, the paper slides downward due to its own weight, is added to the roller 39, is stocked on the intermediate cassette 26, and after all single-sided copying is completed, the paper is delivered to the paper 25 at a predetermined timing. The paper feed roller rotates to transfer the image to the back side of the paper, and the paper guide plate 34 then guides the paper to the paper discharge table 36. Here, the paper guide plate 34 guides the paper guide plate 38 to the duplex paper eject tray at the end of single-sided copying only during back-side copying (however, the feature of this proposal is that it can be The paper is ejected in two parts on paper trays 36 and 37. When making large quantities of copies, a problem often arises is that too many copies are stocked on the paper ejection tray and a jam occurs at the paper ejection roller. Paper output tray 36
When the maximum loading capacity is 100 sheets, the guide plate 34 guides the 101st sheet to the lower double-sided sheet discharge stand and stores it. If the maximum loading capacity of the duplex paper tray is, for example, 50 sheets, the operator is warned by display or voice to interrupt the copying operation and remove the copies from the paper tray. If the operator removes the copy paper from the paper output tray 36, the guide plate 34 guides it to the paper output tray 36 from the next copy. Presence or absence is detected.

In this way, the feature is that the 38 buffer paper ejection trays used for double-sided copying are also used as paper ejection trays for mass copying.

Reference numerals 41 and 42 are optical systems for recognizing the original density pattern and for recognizing the reverse scanning (backscan) reference line (to be described later).This proposal has so far described the functions and control of a double-sided copying machine. This double-sided copying machine, or more appropriately called a simple double-sided copying machine, is unique in its purpose of copying on the back side.

In order to simplify the mechanism of this double-sided copying machine, when copying as is as an analog copy, the leading edge direction of the front and back sides is reversed. When copying the back side, there is no problem if the user reverses the document (reverses the direction in which it is placed on the document table). In the case of this machine, although not shown, the display section will instruct you to reverse the direction of the document when copying the back side. The fact that the image tip is reversed between the front and back sides is not a problem in use. To match the direction of backlight on the front and back sides, the operator can simply turn the document upside down.

However, when using an ADF (automatic document feeder), it is impossible to turn the document upside down.

Therefore, we propose that the scanning optical system be used from the opposite side when copying the back side. When scanning from the opposite direction (backscan), the machine needs to recognize the starting point of the image. There is no problem with scanning in the forward direction because all copiers have a reference line. In other words, a starting point is determined, and the original is aligned with this reference line (usually the upper left corner or lower corner when facing the original table) to copy. However, since the documents used by users vary in size, when scanning in the reverse direction, the reference line is the edge of the document.
You have to find that end face somehow. There are two ways to do that. One is to set the marker as shown in Figure 3 (a) using the Yusaka manual. This marker has a light emitting diode attached at the bottom as shown in FIG. 3(b), and one of the light receiving elements attached to the scanning system detects and recognizes it.

Figure 3(a) is a view of this machine viewed from directly above, and the marker can be moved manually. FIG. 3(a) shows a case where an A4 original is set on the original table. The figure also shows the marker moved to the edge of the document. FIG. 3(b) shows a cross section taken along line AA- in FIG. 3(C). The element at the end of the light receiving element that detects the original density pattern reads the marker. Note that this self-short focus lens array is not a highly accurate one for image formation, and in this example, a five-point fiber lens system is sufficient as shown in FIG. 3(d). The left end of the five points is for marker recognition. Figure 3(c) shows the details of the scanner system in Figure 1. One optical axis is directed toward image formation, and the front optical axis passes through the hole in the reflection mirror to reflect the original. The light then passes through the short focus lens array 41 and hits the light receiving element.

The intensity of this light is A/D converted to detect the density of the original image, and the developing bias potential or the light intensity of the exposure lamp is changed to form a copy with an appropriate density.

Another method is not to use such a marker; instead, there is a light-receiving element (photodiode) that detects such density patterns, so it is sufficient to automatically read the edges of the document. It is a good idea to read the size of the document when scanning in the forward direction (temporarily copying the front side) and memorize the address of the rear edge.

As shown in FIG. 3(e), the original is covered with the original holding plate, and a gap corresponding to the thickness of the original is created between the original and the contact glass. A shadow is created by the difference between the reflection a and the shading of the sainawamaru, and if this is detected, the end face (rear end) can be identified.

The area between X and Y in FIG. 3(e) is where a shadow is created due to the thickness of the document. When you make a normal copy, you will notice that if the paper is large and the original is small, there may be black (stripes) on the edges of the original.

If this is detected, you will automatically know that it is the rear end when scanning in the forward direction. The density difference appears in a curve like the one shown in Figure 3 ([). In the case of normal copying, the appearance of this black outline is a cause of poor image quality, so in order to remove it, an erase lamp on the photoreceptor is sometimes used to remove it. In this case no marker is needed.

Whether the rear end (reference line during backscanning) is detected using a marker or automatically can be determined using the O switch on the control panel. The user usually decides whether to set the density of the copied image to auto or manual, so if it is set to auto, the reference line for backscanning can also be determined automatically. In the case of manual mode, the user sets all the markers, uses the location where the food sensor reads the marker as a reference line, memorizes the address of that reference line, and starts image creation, and in the case of auto mode, the user sets the marker even after reading the marker. Just ignore it.

As described above, when a latent image of the original is formed on the photosensitive drum 20 simply by backscanning the optical system with the trailing edge of the original as a reference, the copy image becomes a mirror image of the original.

As a result, by turning on the mirror image mode switch (not shown) provided on the operation display section DI', the copying machine becomes the mirror image mode, and the document is scanned by the backward movement (backscan) of the optical system, resulting in a mirror image of the document image. You can get a copy.

Next, we will explain how to align the front and back image edges during double-sided copying.

In order to avoid a mirror image due to backscanning as described above when aligning the image front during double-sided copying, the mirror 7 is rotated to the right to direct the reflected light from the original to the mirror 8', as shown in Figure 1. A latent image is formed on the photosensitive drum 20 by the reflected light from the mirror 8'.As a result, a normal original copy image is obtained.
', the optical path length of the photosensitive drum 20 is set to be equal to the optical path length from mirror 7, mirror 8, mirror 9, to photosensitive drum 20.

Further, the mirror 7 is rotated by a pulse motor, and the pulse motor rotates the mirror 7 in the right direction by a preset angle so that the reflected light is irradiated onto the mirror 8'.

FIG. 4 is a flowchart of the control system of this embodiment for back side copying. In step Sl in FIG. 4, a selection is made as to whether or not to perform back side copying.

The condition for back side copying here is whether or not there is paper (paper with copies already made on the front side or blank paper) in the intermediate tray. Further, when the mirror image mode or only the backside copy is selected, only the paper feeding and conveyance processes are activated and blank paper is stocked in the intermediate tray 26.

In step S2, it is determined whether or not the mirror image mode is selected, and if the mirror image mode is selected, the process proceeds to step S5, and if not the mirror image mode, the process proceeds to step S3.

In step S3, it is determined whether or not it is necessary to make the image edges the same in double-sided copying. If the image edges do not need to be aligned, in steps S14, S15, and S16, the document is exposed and scanned by normal forward movement of the optical system. and copy the back side. Further, if it is necessary to align the tip of the image in step S3, the mirror 7 is rotated to the right in step S4 as described above, and the process proceeds to step S5.

Here, whether or not the image tip needs to be aligned is determined by determining whether or not an image edge alignment mode key (not shown) provided on the operation display section DP is turned on.

In step S5, by determining whether the backscan auto key on the operation display unit DP is turned on, whether the start position of the copy process during backscan is detected using a marker set by the operator (manual) or Whether the address of the trailing edge of the document is automatically detected by the photodiode array 42 (
The position selected (Auto) is set as the reference position during backscanning, and in the case of Auto, the address of the detected trailing edge of the document is set as the reference position during backscanning.

When the reference position for backscanning is determined manually or automatically in steps S6 and S7, the process advances to step S8.

In step S8, paper is fed from the intermediate tray 26,
In step S9, a backscan (backward exposure scan) of the optical system is started in SIO to perform a copy process.

When it is determined that the set number of copies have been completed in step Sll, it is determined in step S12 whether copying is in mirror image mode, and if it is not in mirror image mode, mirror 7 is rotated to the left in step S13, and the reflected light is reflected on mirror 8. Make it irradiated.

As described above, the top and bottom of the drawing tip can be freely selected.

In addition, a photodiode array 4 for density pattern recognition
2 can be used to detect the trailing edge of the document.

Furthermore, by specifying the mirror image mode, a mirror image copy of the original can be obtained at will.

Further, it is possible to provide a copying machine having a simple configuration and a double-sided copying function.

In addition, as mentioned above, the photodiode array 42 for density pattern recognition is used to detect the reference point during backscan during backscan auto, but when there is no first diode array for density pattern recognition. In this case, a photodiode for detecting the reference point may be provided.

〔effect〕

As explained above, according to the present invention, if the direction of the image edge of the formed image can be arbitrarily selected, the image can be formed by forward scanning and backward scanning of the original.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of a copying machine according to this embodiment. FIGS. 2(a), 2(b), and 2(c) are diagrams showing the configuration of the control section of the copying machine of this embodiment. FIG. 3(a) is a diagram showing the document table 2 and the operation display section DP. FIG. 3(b) is a diagram showing the marker BM. FIG. 3(C) is a detailed view of the scanner. FIG. 3(d) is a diagram showing an optical system for detecting density patterns. FIG. 3(e) is a diagram showing automatic detection of the end face. FIG. 3(f) is a diagram showing changes in the density pattern. FIG. 4 is a flowchart 1 diagram showing the control operation of the control section of this embodiment. 1 is the document table cover, 2 is the contact glass, 3 is the exposure lamp, 4, 5, 6, 7, 8.8'', 9 is the optical system mirror,
10 is a standard white plate, 11 is a zoom lens, 13 is a charging corona, 14 is a transfer corona, 15 is an erase lamp, 16 is a potential sensor, 17 is a developer, 20 is a photosensitive drum, 22
24 is an upper cassette, 24 is a lower cassette, 26 is an intermediate cassette, 38 is a double-sided paper delivery tray, 41 is a short focus lens, and 42 is a photodiode array.

Claims (1)

[Scope of Claims] Reciprocating means for exposing and scanning a document; image forming means for forming an image based on scanning of the document by the reciprocating means; An image forming apparatus comprising means for forming an image by a forming means.