JPS63124060A - Electrophotography copying device - Google Patents

Abstract

PURPOSE:To execute not only usual copying but also contour image forming copying by installing a second electrifying device instead of a first developing device in a color copying device provided with a first electrifying device and the first and a second developing devices, etc. CONSTITUTION:By the first electrifying device 2, a charge is given to a photosensitive drum 1 which is exposed and a latent image is formed on it. In case of a standard copying mode, a screen image of black or a color is developed by the first developing device and the second developing device 5. Also, in case of a contour image copying mode, the first developing device is removed and the second electrifying device 10 is installed and a high voltage of the opposite polarity, and a low voltage of the same polarity are applied by a scorotron charger 11, and a grid 15, respectively, so that the surface potential of a screen image part is dropped, and the surface potential of a contour image part is not dropped. In this state, a contour image is formed by the second developing device 5, and after the development a transfer 6 is executed. Accordingly, since the second electrifying device 10 can be installed instead of the first developing device, not only usual black and color copying but also contour image copying can be executed, and so the device is prevented from being large in size.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic copying apparatus capable of forming images in a color mode and an outline image forming mode.

In recent years, a variety of electrophotographic copying devices have been provided that are capable of copying not only black images but also red, blue, and other colors, and usually two types of developing devices are used for image exposure. The developing device is disposed between the device and the transfer device, one of which is a regular developing device containing a developer containing black toner, and the other being a color developing device containing a developer containing color toner. can be selectively operated.

On the other hand, in an image, contour lines contain a lot of information, and at the same time fully express the characteristics of the image, and play an important role in the image. Furthermore, images that have been converted into binary figures by drawing contour lines are easier to identify than ordinary grayscale images.

Extremely easy to handle in multiple processes such as determination and transmission,
Converting an image into a binary figure by drawing a contour line is extremely effective in terms of image pattern recognition, image correction/enhancement, bandwidth compression, and the like. In addition, for example, by repeating two copies and adding a colored outline around a black pattern to make it more noticeable, or by painting one pattern in different colors to create patterns with different appearance colors, so-called It is also useful when preparing a coloring pattern.

Therefore, the present applicant has proposed an electrophotographic copying method in which a second charging device is provided between the image exposure device and the developing device, and a contour image is obtained by operating the second charging device. (Patent Application No. 1983-37829.

Patent Application No. 1987-102587, Patent Application No. 1983-10692
Publication No. 3, etc.).

In these methods, if copying is performed with the second charging device turned on, the electrostatic latent image formed on the surface of the photoreceptor can be processed into a contour image before the developing device.
A contour image can be obtained.

By the way, in order to realize the above-mentioned color copying function and this contour image forming function in one copying device, it is necessary to arrange a second charging device in addition to two developing devices around the photoreceptor. However, there is a problem in that an increase in the diameter of the photoreceptor and thus an increase in the size of the copying apparatus itself is unavoidable.

Therefore, it is an object of the present invention to provide an electrophotographic copying apparatus that has both a color copying function and a contour image forming function without increasing the diameter of the photoreceptor or increasing the size of the apparatus.

In order to solve the above problems, the electrophotographic copying apparatus according to the present invention includes a second charging device for forming a contour image between an image exposure device and a developing device. I couldn't help but notice that it would be installed in That is, the first developing device located upstream with respect to the moving direction of the electrophotographic photoreceptor is removable from the main body of the copying apparatus, and the second charging device is connected to the first developing device.
This is an opportunity to make it possible to install it in place of the developing device.

In a configuration of i-month or more, if the first developing device is installed, the color copying function can be selectively copied in the normal copying mode, while the second charging device is installed in place of the first developing device. If you attach the , it becomes possible to copy in outline image formation mode.

Since the second charging device can be installed interchangeably in the position of the first developing device, it does not require any special space, and does not require an increase in the diameter of the photoconductor or the size of the copying device. There's nothing to do.

Figures 1 and 2 show the outline of the electrophotographic copying device, and the first
The figure shows a case where the first developing device (4) is installed, and FIG. 2 shows a case where a contour image forming unit (10) is installed instead. 1
A well-known electrophotographic photoreceptor drum (1) having 1EJI is installed so as to be rotatable in the direction of arrow (a), and around it are the members described below.

The equipment has been installed.

The charger (2) functions as a first charging device that applies a constant potential charge (positive charge in this embodiment) to the surface of the photoreceptor drum (1).

The image exposure device (3) shines light onto the document placed on the document platen glass (35) that can be scanned in the direction of arrow (b) and exposes the surface of the photoreceptor drum (1) using a well-known slit exposure method. It is for forming an electrostatic latent image corresponding to the original image on the image, and is composed of an exposure lamp (31), a lens array (32) in which convergent light transmitting bodies are arranged side by side, and the like.

Both the first developing device (4) and the second developing device (5) use a magnetic brush method to visualize an electrostatic latent image formed on the surface of the photoreceptor drum (1) into a toner image. A stop type magnetic roller (42
), (52) built-in developing sleeve (41), (
51) and a packet roller (43) for mixing and stirring the developer.
), (53). First developing device (4)
A developer containing color toner is stored in the second developing device (5), a developer containing black toner is stored in the second developing device (5), and in the standard copying mode described below, either of the developing devices is used. (4) and (5) can be selectively driven.

The developer is made of a mixture of a magnetic carrier and an insulating toner, and is charged to opposite polarities by frictional charging.
It is charged with the opposite polarity.

Such developer is held like a brush on the surface of the developing sleeves (41>, (51)) by the magnetic force of the magnetic rollers (42), (52), and as the developing sleeves (41>, (51) rotate). In the direction of arrow (d), the height regulating plate (44), (
54), the electrostatic latent image formed on the surface of the photosensitive drum (1) is developed.

The transfer charger (6) applies an electric field from the back side to the copy paper being conveyed in the direction of arrow (c), and applies an electric field to the surface of the photoreceptor drum (1) in the developing device (4) or (5). It is used to transfer the formed toner image onto copy paper.

The separation claw (7) separates the copy paper immediately after transfer from the photoreceptor drum (1).
) to prevent peeling from the surface. The cleaning device #(8) is for removing toner remaining on the surface of the photoreceptor drum (1) using a blade method. The eraser lamp (9) is used to prepare for the next copying process.
This is for removing charges remaining on the surface of the photoreceptor drum (1) due to light irradiation.

On the other hand, the copy paper is fully accommodated in the automatic paper feed cassette (20), and is fed one sheet at a time from the top layer by the paper feed roller (21), and is fed by the timing roller pair (22) as described in detail below. The photosensitive drum (1) and transfer charger (
6). Here, the toner image is transferred, separated from the photoreceptor drum (1) by a separating claw (7), and sent to a fixing device (24) via a guide plate (23) where the toner is fixed. After that, remove the tray (25
) can be discharged on top.

As shown in FIG. 4, the contour image forming unit (10) has approximately the same external shape as the first developing device (4) shown in FIG. It can be attached and detached in exchange for the developing device (4) of No. 1. This unit (10) has a built-in Suflotron charger (11) that functions as a second charging device, a high voltage electric fi (12), and a voltage divider (13). It has a grid (15) shown by.

Further, a sealing member (14) is attached to the bottom of the unit (10) at a location facing the surface of the photoreceptor drum (1). This sealing member (14) is made of a flexible insulating material (for example, polyester film).

When installed in a copying machine, its tip contacts the surface of the photoreceptor drum (1), blocks toner powder smoke generated from the second developing device (5) during copying operation, and protects the Suflotron charger. This prevents the charge wire (11) and the grid (15) from being contaminated with toner particles.Of course, since the sealing member (14) is permanent, it does not disturb the electrostatic latent image on the photoreceptor drum (1). There isn't.

On the other hand, a magnet (16) is installed on the upper surface of this unit (10) and the first developing device (4). When attached to the main body of the copying machine, the magnet (16) turns on the reed switch (103), and the magnet (45) turns on the reed switch (103).
) turns on the reed switch <102), and the unit (1
0) or the first developing device (4) is attached.

Next, the wiring state within the developing devices (4), (5) and the contour image forming unit (10) will be explained.

In FIG. 5a, the first developing device (4) is connected to the connector (
46), and the pin (2) of the connector (46) is connected to the developing sleeve 41).

In FIG. 5b, the contour image forming unit (10) has a connector (17) having the same shape as the connector (46), and the wiring of each pin is as follows.

Pin ■: High voltage electric fi (12) (7) Input terminal (
+24V) pin ■: Input terminal of high voltage power supply (12) (
+OV) pin ■: Remote terminal pin of high voltage power supply (12) ■, ■ Two oven pin ■: "H11 input terminal pin of voltage divider (13) ■
: "L" input terminal of the voltage divider (13) and the casing of the Suflotron charger (11) Also, in the unit (10), the high voltage 'Efi (1
The output terminal of 2) is fully connected to the charge wire of the Sufrotron charger (11), and the output terminal of the voltage divider (13) is fully connected to the grid (15).

On the other hand, the second developing device (5) has a connector (5) connected to the developing sleeve (51), as shown in FIGS. 7 and 8.
5).

Next, the various keys and display section on the operation panel will be explained with reference to FIG.

(110) is a print key that commands the start of copying, (11
1) is the display section for the number of copies, etc., (113), (114>
112 is a group of display LEDs, and the image density is adjusted by increasing or decreasing the amount of light from the exposure lamp (31). (115)
is the numeric keypad from '1' to '0', (116) is the interrupt key that commands an interrupt, and (117) is the clear/stop key that temporarily stops continuous copying and returns the display (111) to '1'. be.

A color mode display LED (118) is lit when the first developing device (4) is installed, indicating that normal black/color copying is possible. (119
) is a key for enabling the operation of the second developing device (5) and selecting copying in black, and (120) is its display LED.

(121) is a key for enabling the operation of the first developing device (4) and selecting color copying, and <122) is its display LED.
It is.

(123) is a contour image forming mode display LED, which is connected to the contour image forming unit (10) instead of the first developing device (4).
It lights up when it is fully attached, indicating that the outline of the original image can be copied. (126) is the standard copy mode selection key, <124) is its display LED, (12
7) is a contour image forming mode selection key, and (125) is its display LED.

Note that even if the contour image forming unit (10) is completely installed, it is possible to form an image that corresponds one-to-one to the original image if the copying operation is performed with the Suflotron charger (11) turned off. The selection key (126) is for selecting such a mode.

Figures 7 and 8 show the control circuit of this copying apparatus, and Figure 7 shows the case where the first developing device (4) is installed, and Figure 8 shows the case where the contour image forming unit (10) is installed instead. Indicates the case where

It can be controlled mainly by a microcomputer (CPU). That is, the (CPU) has a selection key (119).

(121), (126), (127) on/off signals, etc. can be input, and various displays L E D (1
1B), (120), (122) to (125), etc., can output on/off signals. In addition, from the (CPU), the main motor of the copying machine, the eraser lamp (9),
1st. An on/off signal is output to the second developing motor and the like.

The developing bias 'Km (55) is controlled by a signal from the (CPU) and supplies a predetermined bias voltage to the pin (1) of the connector (101) and the pin (2) of the connector (102). Further, a DC power supply (120) is connected to pins ■ and ■ of the connector (102), pin ■ is connected to (CPU), and pin ■ is grounded.

The connectors (17) and (46) are automatically connected when the contour image forming unit (10) or the first developing device (4) is attached to the main body of the copying apparatus.

When the first developing device (4) is installed, as shown in FIG. 7, the connector (101) is connected to the developing sleeve (41).
, (46), a developing bias of a predetermined voltage can be applied through pin (46).

When the contour image forming unit (10) is installed, as shown in FIG.
1), (17) pins ■, ■ to the DC power supply (12
0), a voltage of +24V can be applied at all times. Turn on the output of the high voltage power supply (12) operated by this DC power supply (120).

Off is (cpu> by connector (Lot), (1
A bias voltage is applied from the developing bias power supply (55) through the connector (101) and the pin (17) to the 0 voltage divider (13) which can be controlled through the pin (7).
After reducing the partial voltage to a predetermined voltage value, it can be supplied to the grid (15).

On the other hand, a developing bias of a predetermined voltage is applied to the developing sleeve (51) of the second developing device (5) from the developing bias power source (55) via the connectors (102) and (55).

By the way, the charge wire of the Suflotron charger (11) is connected to the high voltage power supply (12), and in the case of the present embodiment in which a positive original image is exposed to form a positive contour latent image, the charge wire of the charger (2 ) is applied with a voltage of opposite polarity.

In addition, the grid (15) is connected to a voltage divider (
13), a voltage having the same polarity as the voltage applied to the charger (2), sufficiently lower than the surface potential of the electrostatic latent image image area, and slightly higher than the surface potential of the non-image area is applied.

When non-magnetic insulating toner is used in the developing sleeve (51), a voltage slightly higher than the grid voltage and of the same polarity as the charger (2) is supplied from the developing bias power source (55). Developing bias can be applied completely. In the case of this embodiment, the voltage value of this developing bias is substantially the same as the electrostatic latent image image whose potential has been lowered by the corona discharge of the Sufrotron charger (11) in the second band process described below. The surface potential can be set slightly higher than the surface potential at the center of the area.

Specifically, the polarity and voltage values shown below are set.

Charger [power supply voltage positive polarity +5.5kV Suflotron charger [ti(12)]] negative polarity -6. Ok V lid [Voltage divider (13) positive polarity + 150v Grid-photoconductor surface distance (dg) 1.5 mm Developing bias [power supply (55) positive polarity + 200V Transfer charger [power supply voltage positive polarity + 5.5 kV Non-magnetic insulation Toner with negative polarity Note that all of these polarities may be reversed,
Of course, the voltage values and the like are merely examples.

The method for forming an image using the copying apparatus described above will be explained in order of steps.

(Contour Image Formation Mode) This contour image formation mode is executed by turning on the selection key (127).

(1) First charging step A charger (2) applies a constant electric charge to the surface of the photoreceptor drum (1). As a result, in this example, the surface potential of the photoreceptor drum (1) is +600V.

(i) Exposure step A positive original image is exposed to slit light on the surface of the photoreceptor drum (1) charged to a potential of +600V to form an electrostatic latent image. In this case, as shown in (a) in FIGS. 9 and 10, the charges in the portions corresponding to the image areas (A) and (B) are +
The potential remains at 600V, and the charge in the portion corresponding to the non-image area decreases to about +80V by light irradiation.

(i) Second charging step The surface of the photoreceptor drum (1) on which the electrostatic latent image has been formed is charged with a Sufrotron charger (11) to which a heavy pressure of -6,000 kV is applied from the power source (12). Recharge.

At this time, a heavy pressure of +150V is applied to the grid (15) from the power supply (55) via the voltage divider (13). The voltage that can be applied to the Sufrotron charger (11) is of opposite polarity to the voltage that can be applied to the charging charger (2). Furthermore, the heavy pressure that can be applied to the grid (15) has the same polarity as the voltage applied to the charger (2) and the surface potential (+600V) of the electrostatic latent image areas (A) and (B).
The voltage value is sufficiently lower and slightly higher than the surface potential (+80V) of the non-image area.

Electric lines of force shown by arrows in FIG. 9 are formed between the surface of the photosensitive drum (1) and the grid (15).

Then, the negative polarity ions generated from the charge wire are subjected to a transport force along the lines of electric force. In this case, negative polarity ions are applied to the photoreceptor drum (15) near the grid (15).
The electric lines of force directed toward the surface of ) are generated only in a portion (hereinafter referred to as the central portion) excluding the inner side of the contour line (A゛) of the surface image portion (A>).

Therefore, the negative polarity ions are in the surface image area (as shown by the arrow →).
The charge reaches only the central part of A>, eliminates the charge in the reached part, and lowers it to around the first position, which is approximately equal to the grid voltage (+150V) [see (b) in Fig. 10.

That is, in terms of the surface potential of the photoreceptor drum (1), as shown in FIG. 10(b), the surface potential of the non-image area of the electrostatic latent image remains as a low potential area of approximately +80V, and the surface potential of the image area The inner parts (A') and (B') of the contour lines in (A) and (B) remain as high potential parts with a constant width of approximately +600V, which is the initial surface potential, and the surface image part (A) The central portion drops to approximately the grid voltage (Vg: +150V). Note that, although the surface potential of the line image contour portion (Bo) hardly decreases, the width of one load is slightly narrowed.

In other words, the image area (A) in this second charging step.

The contour portion shown in (B) is formed as a positive electrostatic latent image.

(iv) Development error The electrostatic latent image formed as a positive image of the outline in the second charging step is developed in the second developing device (5).
In this embodiment, the developing sleeve (51) is equipped with a power source (5
5), a developing bias of +200V can be applied. This developing bias is applied in order to prevent toner from adhering to the central part of the electrostatic latent image area (A) where the surface potential has decreased in the second charging process (and of course also to non-image areas). The voltage (vb>) has the same polarity as the voltage applied to the charging charger (2) and is slightly higher than the surface potential of the central portion of the surface image area (A) that has decreased in the second charging step.

In this way, the negatively charged insulating toner is applied to the high potential areas of the photoreceptor drum (1), that is, the areas (A') and (B') inside the contour lines of the image areas (A) and (B). A so-called "inner border" toner image is formed by regular development.

This toner image is then transferred onto the copy paper by the positive discharge of the transfer charger (6), and is formed as a copy image via the fixing device (24).

(Standard copy mode) This standard copy mode is used to obtain a copy image that corresponds one-to-one to the original image, and is automatically set when the first developing device (4) is installed. Ru. In this case, by turning on the selection keys (119) and (tzl), it is possible to select the developing device <5) or (4) and copy in black or color.

On the other hand, the contour image forming unit (10) is installed.
If so, it is executed by turning on the selection key (126).

(i) First charging step This is the same as in the contour image forming mode.

(i)! The light process is the same as in the contour image forming mode, and is shown in FIG. 10 (
A positive electrostatic latent image shown in a) is formed.

(i) Second charging process When the contour image forming unit (10) is installed, the charging process is completed. (12), the voltage divider (13) are both turned off, and the Suflotron charger (11) does not operate. Therefore, the positive electrostatic latent image formed in the exposure process is directly transferred to the second developing device (5). ) to reach. - On the other hand, if the first developing device (4) is installed and the color mode is fully selected, development is performed here.

(iv>Developing step Here, negatively charged insulating toner (black or color) is applied to the image area (A) shown in (a) in FIG.
B), and a toner image corresponding to the original image on a one-to-one basis is formed by regular development. In this case, the developing bias is +200V.

Next, referring to the flowcharts in Figure 11 and below, (CP
The control procedure according to U) will be explained.

11th v! ! J indicates the (CPU) main routine.

When the power is turned on, (CPtl) is reset,
When the program starts, first step (Sl)
In step (S2), an internal timer is started. It determines the time required for one routine of the main routine, regardless of the processing content in the subroutine, and its value can be set in advance in step (Sl).

Next, the subroutines shown in steps (S3) to (S7) are sequentially called, and when the processing of all subroutines is completed, the process waits for the internal timer to end in step (S8), and then returns to step (S2). The time length of one routine is used to count the various timers that appear in each subroutine.

The subroutine of step (S3) includes photoreceptor drum (1
) is performed to remove the inter-image charge on the image and will be detailed later.

The subroutine of step (S4) is executed to set the operation of the developing devices (4) and (5) according to the selected copy mode, and will be described in detail later.

The subroutine of step (S5) is executed to display the copy mode selected on the operation panel according to the on/off of mode selection keys (119), (121), etc. on the operation panel, and will be described in detail later.

The subroutine of step (S6) is for controlling the copy operation, and the copy operation in the selected copy mode can be executed based on turning on the print key (110). In particular, if the various keys on the operation panel are not operated within a certain period of time after copying in the contour image forming mode is completed, the mode returns to the standard copying mode. Note that this point will be explained in detail below.

The subroutine of step (S7) is for executing other processes, such as fixing temperature adjustment, and its details will be omitted.

FIG. 12 shows an erase subroutine that can be executed in step (S3).

First, in step (511), it is determined whether the power has just been turned on (within a predetermined time since the power was turned on).

If NO, proceed to step (515); if YES, turn on the main motor in step (512), turn on the eraser lamp (9) in step (513), and remove the charge on the photoreceptor drum (1). Erasing can now begin. At the same time, a timer (TM') is set in step (514), and the process proceeds to step (S-15). A timer (IM) is set to the time required for this erase.

In step (515), it is determined whether the timer (TM) has expired. If the process has not ended, the process returns to the main routine; if it has completed, the eraser lamp (9) is turned off in step (516), the main motor is turned off in step <517>, and the process returns to the main routine. □FIG. 13 shows a subroutine for selecting the development mode executed in step (S4).

First, in step (521), it is determined whether or not the reed switch (102) for detecting the first developing device (4) is off, and if it is off, the process proceeds to step (522), and if it is on, the process proceeds to step (522). Proceed to (527). Step (522
), it is determined whether the reed switch (103) for detecting the contour image forming unit <10) is off, and if it is off, the process proceeds to step (523), and if it is on, the process proceeds to step (53g).

If NO is determined in both steps (521) and (522), the color flag is set to “O” in step (523).
', and if '0', step (524)
Set the color flag to "1" with . Then, in step (525), it is determined whether the mode flag is rl,
11”, the mode flag is set to “11” in step (526).
0" and return to the main routine. That is, the first
If neither the developing device (4) nor the contour image forming unit (1o) is installed, set the color flag to 1"1.
” and reset the mode flag to “I″O”.
The mode is set to operate the second developing device (5).

Further, in the step (521), the reed switch (10
2) is turned on and it is determined that the first developing device (4) is attached, it is determined in step (527) whether the reed switch (102) has been turned on from off. If YES, execute step (528) and below,
If NO, step (532) and subsequent steps are executed. In step (528), it is determined whether the color flag is "0" or not, and if it is "0", the color flag is set to rl in step (529). Then, in step (530), it is determined whether the mode flag is ``o'' or not. If it is ``0'', the mode flag is set to ``11'' in step (531), and the process returns to the main routine. That is, the first developing device (4)
If the developing device (4) has just been installed, the color flag and mode flag are set to "1" to set the mode in which the first developing device (4) is operated.

In the step (527'), the reed switch (102)
If it is determined that is continuously on, step (53
In step 2), it is determined whether the color flag is "0." If it is "0", the color flag is set to "1" in step (533).Next, in step (534), the color selection key (121) is set. ) is turned on and whether or not the black selection key (119) is turned on in step (536).If the 0 selection key (121) is turned on, step (535) is performed.
) to set the mode flag to "1." and return to the main routine. If the selection key (119) is turned on, step (
536) resets the mode flag to "o" and returns to the main routine with the 0 selection key <121).

If none of (119) are turned on, the mode flag remains as before and the process returns to the main routine. That is, the color selection key (1) is pressed while the first developing device (4) is fully installed.
21) is turned on, the mode flag is set to "1" and the color flag is f''1''), the first developer bag #(4)
Set the mode to operate. In addition, the black selection key (
119) is turned on, the mode flag is reset to "0." and the color flag is set to "I"1. ), second developing device (
5) Set the mode to operate. Furthermore, if neither of the selection keys (121) and (119) is turned on, the previously set development mode is maintained.

Meanwhile, in the step (522), the reed switch (10
3) is turned on and it is determined that the contour image forming unit (10) is attached, it is determined in step (S38) whether the reed switch (103) has been turned on from off. If YES, step (539) and subsequent steps are executed, and if No, step (543) and subsequent steps are executed. In step (539), it is determined whether the color flag is 11'', and if it is ``rl'', the color flag is reset to 1''0'' in step (540). Further, in step (541), it is determined whether the mode flag is 10'', and '
0”, the mode flag is set to rl in step (542).
, and return to the main routine. That is, if the unit (10) has just been installed, the color flag is set to 1.
0” and set the mode plug to “1.”
While operating the unit (10), the second developing device (
5) Set the mode to operate.

If it is determined in step (538) that the reed switch (103) is continuously on, step (543)
> to determine whether the color flag is "11", and if it is "1", the color flag is reset to "0." in step (544).Next, in step <545>, the contour image formation mode selection key ( If the 6 selection key (127) is turned on, the mode flag is set in step (S46). Set it to "1" and return to the main routine. If the selection key (126) is turned on, the mode flag is set to "0" in step (548).
” and return to the main routine. 0 selection key (1
27), (126) are not turned on,
The mode flag remains as before and returns to the main routine. That is, if the contour image forming mode selection key (127) is turned on while the unit (10) is fully attached, the mode flag is set to ``1'' and the color flag is set to ``OJ''. Second developing device (5)
Set the mode to active mode. Also, when the standard copy mode selection key (126) is turned on, the mode flag is set to 1.
The color flag should be set to "0".
10) is set to a mode in which the second developing device (5) is operated without operating. Furthermore, select key (127
).

If none of (126) are turned on, the conventionally set development mode can be maintained.

FIG. 14 shows a subroutine for panel display executed in step (S5).
According to the development mode set in the subroutine of S4), each display LED is turned on and off to display on the panel.

That is, first, in step (S51), the color flag is set to 11.
”, and if YES, step (552)
Turn on the color mode display LED (118) with
Turn off the contour image forming mode display LED (123).

Furthermore, in step (553), it is determined whether the mode flag is rIJ or not. If YES, proceed to step (554), and if NO, proceed to step (555). In step (554>, color mode display L E D (122
) to display other modes L E D (120),
Turn off (124) and (125) and return to the main routine. In step (555), black mode display L E
Turn on D (120) and display other displays L E D (1
22), (124), and (125) and return to the main routine.

On the other hand, when the color flag is 1"0", the step (551
), the contour image forming mode display LED (123) is turned on and the color mode display LED (11g> is turned off).Furthermore, in step <557) the mode is turned on. Determine whether the flag is "1" or not. If YES, proceed to step (558); if NO, proceed to step (559>; step (
At step 558), the black mode display LED (120) and the contour image forming mode display LED (125) are turned on, the other display LEDs (122) and (124) are turned off, and the process returns to the main routine.

In step (559), the black mode display LED (
120) and standard copy mode display LED (124)
Turn on the contour image forming mode display L E D (12
5) Turn off the color mode display LED (122) and return to the main routine.

FIGS. 15a, 15b, and 15c show the steps (
The subroutine for the copy operation executed in S6> is shown.

First, in step (561') press the print key (110).
It is determined whether or not the flag is turned on, and if it is not turned on, the process proceeds to step (563). If it is turned on, the copy start flag is set to 11 in step (562), and the process proceeds to step (56).
Proceed to 3). The copy start flag is thus set to "11" when the print key (110) is turned on, and is reset to "0." in the following step (577) upon completion of copying.

Next, in step (563), the copy start flag is set to "1".
”, and if it has been reset to “rO”, the process proceeds to step (581) described below.

If set to 1, turn on the main motor in step (564), determine whether the color flag is "O" in step (565), and proceed to step (566) in either case of YES or NO. Or in step (569), it is determined whether the mode flag is "1." If the color flag is "0." and the mode flag is "1", the contour image forming mode is selected, so step (567) is performed. ) turns on the motor of the second developing device 5), and connects the developing bias source (55) to the high-voltage electric power source (55). Turn on (12) and proceed to step (572). color flag.

If both mode flags are 10, the standard copying mode using black toner is selected, so step (5)
6g) to turn on the motor of the second developing device (5) and the developing bias mold! Turn on (55) and step (5
72), set both the color flag and mode flag to "1.
In this case, the color toner copying mode has been selected, so in step (570) the first developing device (
Turn on the motor 4) and turn on the developing bias power supply (5).
5) and proceed to step (572). If the color flag is rl and the mode flag is "0.", the copy mode with black toner is selected, so the same as step (568) is performed. In step (571), the motor of the second developing device (5) is turned on and the developing bias mold (55) is turned on, and the process proceeds to step (572).

Next, in step (572), paper feeding and conveyance control, in step (573), control of the optical system (3), and in step (574).
The charger and the like around the photosensitive drum (1) are controlled. These controls are well known and their explanation will be omitted. Furthermore, in step (75) it is determined whether or not copying has been completed for a predetermined number of copies, and if the copying has not been completed, step (75) is performed.
581), and if completed, turn off the motor of the developing device (4) and (5), the developing bias power source (55), and the high voltage 1L source (12) in step (576), and then in step (577). The main motor is turned off and the copy start flag is reset to r□.

Next, in step (578) it is determined whether the color flag is r□, and in step (579) it is determined whether the mode flag is "11". If NO in either step (581
), and if YES in both cases, that is, if copying was completed in the contour image formation mode, proceed to step (
Set the timer (To) at step (580) and proceed to step (58
Proceed to 1).

In step (581), it is determined whether any key on the operation panel has been turned on. If it is turned on, the timer (To) is reset in step (582) and the process returns to the main routine. If neither key is turned on, it is confirmed in step (583) that the timer (To) has timed up, and the mode flag is reset to "0" in step (584). In other words, if a contour image forming mode that is generally infrequently used is selected and any key on the operation panel cannot be turned on within a certain period of time set in the timer (To) after copying is completed. Automatically switches to the frequently used standard copy mode. This prevents the problem of erroneously copying in the contour image forming mode during the next copying.

Note that the electrophotographic copying apparatus according to the present invention is not limited to the above-mentioned embodiments, and can be modified in various ways within the scope of the gist thereof.For example, in the contour image forming mode, the second developing device (5) The developing bias applied to the developing sleeve (51) may include alternating current superimposed on direct current, which is particularly effective when magnetic insulating toner is used. In this way, when an insulating toner with magnetism is used, there is a threshold value due to the magnetic binding force, so for example, the voltage value (vb) of the developing bias in the contour image forming mode in the above embodiment is The voltage can be set to be slightly lower than the surface potential of the central portion of the surface image area (A) whose potential has decreased in the second charging step.

On the other hand, in the embodiment described above, a direct current voltage is applied to the Suflotron charger (11), which is the second charging device, but an alternating voltage may be applied thereto. In this case, in the second charging step, the surface potential of the central portion of the electrostatic latent image surface image area (A) decreases to approximately the grid voltage, and the surface potential of the non-image area remains at the outside of the contour line. The voltage will rise almost to the grid voltage.

In addition, as a contour image forming method, by changing the polarity of the second charging device [Sufrotron Charger (11)], the development method (regular development or reverse development), etc. methods for forming contour images, methods for forming positive contour images from negative originals, etc.
Various methods exist.

As is clear from the above description, according to the present invention, the first. a second developing device is provided;
A first developing device located on the upstream side with respect to the moving direction of the electrophotographic photoreceptor is detachable, and a second charging device for forming a contour image is attached in place of the first developing device. This makes it possible to perform not only normal black toner copying and color toner copying, but also contour image forming functions compared to conventional color copying machines, without increasing the diameter of the photoreceptor or the accompanying enlargement of the copying machine. They can be grouped into the same type.

[Brief explanation of the drawing]

The drawings show an embodiment of the electrophotographic copying apparatus according to the present invention, and FIGS. 1 and 2 are schematic diagrams of the apparatus, FIG. 3 is a perspective view of the first developing device, and FIG. 4 is a contour image. FIG. 5a is a perspective view of the forming unit, and FIG. 5b is an explanatory diagram of the wiring of the first developing device.
The figure is an explanatory diagram of the wiring of the contour image forming unit, Figure 6 is a plan view of the operation panel, Figure 7 is a block diagram of the control circuit when the first developing device is installed, and Figure 8 is the outline image forming unit. A block diagram of the control circuit when installed, FIG. 9 is a schematic diagram of electric lines of force due to the second charging device, FIG. 10 is a graph showing the potential of the electrostatic latent image in each image forming process, and FIG.
Figures 15c to 15c are flowcharts showing the control procedure. (1)...Electrophotographic photosensitive drum, (2)...First
charging device, (3)... optical system, (4)... first developing device, (5)... second developing device, (6)...
Transfer device, (10)... Contour image forming unit, (1
1)... Sufrotron charger (second charging device), (15)... Grid.

Claims (1)

[Claims] 1. Along the moving direction of the electrophotographic photoreceptor, at least a first charging device, an image exposure device, first and second developing devices,
In an electrophotographic copying apparatus that is provided with a transfer device and that forms copy images of different colors by selectively operating a first and second developing device, An electrophotographic copying device characterized in that a first developing device located on the upstream side is removable from the main body of the copying apparatus, and a second charging device can be attached in place of the first developing device. Device.