JPS62163041A - Image forming device - Google Patents

Abstract

PURPOSE:To select optionally a top or bottom of a picture head by setting up a back end position of an original detected by a detecting means as a reference position for image formation when the image is to be formed by the backward movement of a reciprocating member. CONSTITUTION:Manual or automatic operation is selected by deciding whether an auto-backscanning key on an operation display part is turned on or not. A position setting up a marker is regarded as a reference position for backscanning in case of manual operation, and in case of automatic operation, the address on the back end of the detected original is regarded as a reference position for backscanning. When the reference position is determined, paper is fed from an intermediate tray 26 and the backscanning (forward exposure scanning) of an optical system is started to execute a copying process. When the completion of the set number of copies is decided, whether the copies are based on a mirror image mode or not is decided, and if the copies are not based on the mirror image mode, a mirror 7 is rotated in the counterclockwise direction so that reflected light is irradiated to a mirror 8.

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 double-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. For this reason, a structure for reversing the copy paper must be provided, which has the drawback of complicating the structure of the copying machine.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that eliminates the above-mentioned conventional example and detects the trailing edge position of a document and uses the detected trailing edge position as a reference position for backward scanning of the document by a reciprocating member. be.

[Example 1] 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). When reducing or enlarging the image using an operation unit (not shown), set the magnification ratio as necessary using the magnification 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 the duplex mode is selected and the copy start key is turned on, the halogen lamp 3 lights up, the photosensitive drum 20 rotates, and the charged corona 13 is energized. The halogen lamp 3 and the first mirror have the same structure.
An optical axis is formed by the fourth mirror 7, fifth mirror 8, and sixth mirror 9 through the zoom lens 11, and an image is formed on the drum surface.

The surface potential of the image on the drum surface (latent image) 15 is removed by an erase lamp 15, 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 classification roller 31 and conveyed to a fixing section 33 by a paper conveyance belt 32. Here, heat and pressure are applied to fuse the toner. 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 is not stocked on the double-sided paper tray 38.

In this way, the number of sheets whose front side has been copied is stored in the intermediate cassette. On the other hand, the image on the drum surface (h) which has been transferred 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 roller 30 is rotated at a predetermined timing to align the leading edge of the image, 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. 31
The image is separated from the drum by a separation roller, and conveyed to a fixing section 33 by a conveyor belt 32. Here, the toner is fused. It is then added to 40 rollers. The guide plate 34 is then guided to the paper discharge tray 36, and the transfer paper that has been copied on both sides is stocked on the tray 36. In this way, the double-sided copying process is completed. In the case of normal single-sided copying, the guide plate guides the paper to 36 paper discharge trays. 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 2o with the light reflected by the standard reflector IO and monitoring it with 16 surface potential sensors to determine the appropriate level. First, the corona voltage of 13 is controlled so that the value is the same.During the copy operation, when the user selects automatic selection, the optical system performs prescanning to monitor the original, and monitors the density of the original. Set the corona voltage and bias value.If the prescan operation is troublesome because it monitors each copy, you can control the developing bias value to achieve the appropriate density while monitoring the density of the original 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 for the second copy.Also, the original density can be detected. The function samples the reflected light hitting the document surface and detects 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, such as serious abnormalities such as an abnormal rise in the fixing temperature, abnormal lighting of the exposure lamp, and paper jams, and minor abnormalities such as empty paper and empty toner. Also, before copying, a diagnosis is performed to see if there are any abnormalities.

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. controller! Reference numeral 06 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 Io5 will be explained based on FIG. 2(b). 105-1 is CPU105-2
This is an oscillator 105-1 that supplies a heclock wave.

105-2 is a CPU which is a control unit of the controller 105.
It consists of a microcomputer and peripheral devices for the microcomputer such as RAM and ROM. 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 includes an A/D converter for inputting a document sensor 105-3, a potential sensor 16, and a temperature sensor 105-5.

A drum encoder circuit +05-6 counts encoder pulses generated by the rotation of the drum drive motor of the copying machine and outputs TI pulses for timing control. Reference numeral 105-7 is a zero pulse detection unit that detects the zero cross pulse TO of the AC power source. The zero cross pulse TO of the AC power source is used for the zero cross trigger of the AC power source in controlling the count pulse for the timer, temperature, and exposure lamp.

+05-9 and +05-10 are I10 expansion chips.

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.

Further, the CPU 105-2 of the controller 105 is I10
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 105-2. 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 a RAM and a 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. 1
06-6 is a servo motor controller that drives and controls the main motor 106-8. 106-9 is an optical encoder 1 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 controllers 105 and 106 perform normal copying operations such as paper feeding, charging, exposure, development, transfer, conveyance, fixing, and
The copying process includes paper ejection and photoconductor cleaning.

The controller 105 also includes 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 double-sided paper output stand of . 38, the paper slides downward due to its own weight, is added to the roller 39, is stocked in the intermediate cassette 26, and after all single-sided copying is completed. At a predetermined timing, the paper feed roller 25 rotates to transfer the image to the back side of the paper, and the paper guide plate 34 then guides it to the paper output tray 36. Here, the paper guide plate 34 is used for back side copying. However, the feature of this proposal is that when copying in normal single-sided mode, especially when performing large-ejection copying, the paper is ejected into two duplex trays 36 and 37 at the end of single-sided copying. Often, when making large-scale copies, 11/(7100Fr1)-l, 1 tlE!ff
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If the paper is removed too much, a jam may occur at the paper ejection roller.

When the maximum loading capacity of the paper discharge tray 36 is 100 sheets, the guide plate 34 guides the 101st sheet to the lower double-sided paper discharge tray 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 output tray 36, the guide plate 34 will be removed from the next copy.
The presence or absence of paper is detected by microswitches or photosensors on the paper discharge trays 36 and 38 leading to the paper discharge trays 6 and 6, respectively.

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. Although it would be more appropriate to call this double-sided copying machine, ie, a simple double-sided copying machine, the purpose of the proposal is that it is unique in 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 back and the back is not a big problem when using it. 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 for the user to manually set the marker as shown in FIG. 3(a). 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 to use a light-receiving element (photodiode) that detects such a density pattern and automatically reads the edge of the document without using such a marker. 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.

In Figure 3(e), the original is covered with the original holding plate, and there is a gap between the thickness of the original and the contact glass. This creates a shadow, and by detecting it, 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 as shown in FIG. 3Cf). In the case of normal copying, the appearance of this black outline causes poor image quality, so in order to remove it, an erase lamp is sometimes used to illuminate the photoreceptor. In this case, a marker is not required.

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 DP, the copying machine enters 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 during image front alignment during double-sided copying, the mirror 7 is rotated to the right as shown in Figure 1, and the light reflected from the original is reflected onto the mirror 8-. A latent image is formed on the photosensitive drum 2o by the light from the mirror 8'. As a result, a normal original copy image can be obtained. In addition, mirror 7, mirror 8
', the optical path length of the photosensitive tram 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 tip alignment mode key (not shown) provided on the operation display section DP is turned on.

In step S5, by determining whether the hack scan auto key on the operation display unit DP is turned on, the start position of the copy process during backscanning is detected using a marker set by the operator (manual); Alternatively, select whether the address of the trailing edge of the document is automatically detected by the photodiode array 12 (auto). In manual mode, the position where the marker is set is used as the reference position during backscanning, and in automatic mode, the address of the detected trailing edge of the document is used as the reference position during backscanning.

When the reference position for backscanning is determined manually or automatically in step S36 and S7, the process advances to step S8.

In step S8, paper is fed from the intermediate tray 26,
In step S9, a hack scan (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 SI2 whether copying is to be performed in mirror image mode, and if it is not mirror image mode, mirror 7 is rotated to the left in step S13, and 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
By detecting the trailing edge of the document using 2, it can be used to detect one point of disarray during backscanning.

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, the density pattern recognition ArJg is used to detect the reference point during hack scan during backscan auto, as in ``double series''.
Although a first diode array 42 is used for the purpose, if there is no photodiode array for density pattern recognition, a first diode for reference point detection may be provided.

〔effect〕

As explained above, according to the present invention, the reciprocating member that scans the original document can perform backward scanning, and the direction of the tip of the image to be formed (1) can be arbitrarily selected.

[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(l) 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 an original table horn bar, 2 is a contact crow, 3 is an exposure lamp, 1, 5, 6, 7, 8.8-. 9 is an optical system mirror, 10 is a standard white plate, 11 is a zoom lens, 13 is a charging corona, 111 (a wide photo corona, 15 is an erase lamp, 16 is a potential sensor, 17 is a developer, 20 is a photosensitive drum, 22 is an upper cassette, 24 is a lower cassette, 26 is an intermediate cassette, 38 is a double-sided paper output tray, 41 is a short focus lens,
・12 is a photodiode array. q [Saka/'e? - Piping system 30rC1) 11th a-LIFL 4ftt nitriding of turns 1:r30 adjustment button d2 reeds 1
Figure 3 (S)

Claims (1)

[Scope of Claims] A reciprocating member that exposes and scans a document; an image forming member that forms an image based on scanning of the document by the reciprocating member; a detection unit that detects a trailing edge of the document; and a reciprocating member. When forming an image by the backward movement of the image forming apparatus, the image forming apparatus is characterized by having means for causing the image forming means to form an image by using the trailing edge position of the document detected by the detecting means as a reference position for forming the image. .