JPH01167859A - Copying machine - Google Patents

Abstract

PURPOSE:To shorten the exposure time by making the polarity of the toner for developing a latent image formed by a primary exposure means for analog exposure and the toner for developing a latent image formed by a secondary exposure means for digital exposure different from each other. CONSTITUTION:A circuit for the title device has an inversion process port which inverts data signals according to the instruction of a main controller 500 after an image data has been read. The inversion process part carries out black-and-white inversion of a normal image. Furthermore, when a laser is beamed to a position where the toner shall be placed according to the polarity of the toner in order to develop the latent image formed on a drum 1, or to the contrary, when the laser is beamed onto a position where the toner is not to be placed, the image scan and the background are switched at the inversion process part 807. In this case, since a drum 1 is used both for the analog exposure and the digital exposure, by inverting the image with the inversion process part 807, exposure can be obtained which matches the toner polarity, and the exposure time is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a copying machine having two exposure systems, an analog exposure system and a digital exposure system.

[Prior Art] Generally, a copying machine has two exposure systems, an analog exposure system and a digital exposure system, and after forming a latent image on a photosensitive drum by one or both of the exposure systems, the latent image is developed, Copying machines that perform transfer are known.

In analog exposure, illumination light is projected onto a document, and the photoreceptor is exposed to light using the reflected light. In digital exposure, a semiconductor laser or the like is driven to expose a photoreceptor to a light beam.

[Problems to be Solved by the Invention] However, in analog exposure, toner adheres to areas of the photoreceptor that are not exposed to light, so in order to develop the latent image formed on the photoreceptor drum using the same toner, Digital exposure has the problem that exposure scanning (backscanning) must be performed on areas other than the image to be recorded, which lengthens the exposure time and, as a result, shortens the life of the semiconductor laser.

Therefore, the purpose of the present invention is to solve such problems,
It is an object of the present invention to provide a copying machine that can adhere toner to a digitally exposed portion of a photoreceptor even in a copying machine that performs analog exposure and digital exposure.

[Means for Solving the Problems] In order to achieve such an object, the present invention includes a photosensitive means that forms a latent image by exposure, and a second device that exposes and scans an original image on the photosensitive means via an optical system. a first exposure means; a second exposure means for exposing and scanning an image on the photosensitive means based on an electrical signal; and a first toner having a first polarity formed on the photosensitive means by the first exposure means. and a developing means for developing the latent image formed on the photosensitive means by the second exposure means with a second toner having a second polarity different from the first polarity. .

[Function 1] In the present invention, a toner for developing a latent image formed on the photosensitive means by the first exposure means performing analog exposure and a latent image formed on the photosensitive means by the second exposure means performing digital exposure are used. Since the polarity of the toner used for development is made different, the area exposed by the second exposure means can be used as an image to be recorded.
The exposure means no longer needs to perform backscanning. As a result, the exposure time of the second exposure means is also shortened, and the life of the second exposure means can be extended.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the configuration of an embodiment of the present invention.

In FIG. 1, 1 is a drum on which a latent image is formed, and the surface of the drum 1 is made of a seamless photoreceptor using a photoconductor. Reference numeral 2 denotes a motor that drives the drum 1, and rotates in the direction of the arrow in response to depression of a copy start key or an external print start signal. 3 is a high-pressure unit that charges the drum 1 with corona.

When performing analog exposure, the original placed on the original table glass 5 is irradiated by the exposure lamp 4, and the mirrors 6.7, 8.
Lens 9. Reflected light from the original is imaged onto the drum 1 through mirrors 10, 11, and 12. The image formed by this reflected light will be referred to as an analog image.

When performing digital exposure, image information is outputted as laser light by the laser unit 13 and is imaged onto the drum l through a mirror. An image formed by laser light in this manner will be referred to as a digital image.

The laser unit 13 turns the semiconductor laser on and off based on image information. The projected laser beam is deflected by a rotating polygon mirror (not shown) so as to scan in the direction of the drum axis.

In this embodiment, both the analog image and the digital image are
By forming an electrostatic latent image on top of the device, the device is miniaturized.

Next, the electrostatic latent image formed on the drum 1 is developed by a developer 14 or 15 and visualized as a toner image, and the toner image is transferred to a transfer paper by a transfer charger 16.

17 is an upper cassette, 18 is a lower cassette, and 19 is a paper deck. The sheet is fed into the main unit from either the lower cassette 1B or the paper deck 19 by paper feed rollers 20, 21, 22, and registration rollers 23 align the leading edge of the latent image with the leading edge of the transfer paper with accurate timing.

After the transfer is completed, the transfer paper is separated from the drum 1 by a separation charger 24, guided to a fixing device 26 by a conveyor belt 25, and fixed by pressure and heat. It is then discharged outside the main body.

During double-sided copying or multiple copying, eject flapper 2 after fixing.
7 and the copied transfer paper is stored in the intermediate tray 202 via the conveyance path 201 of the duplex unit 200.

At this time, the multiplex flapper 203 is lowered when double-sided, and raised when multiplexed, changing the surface when storing in the intermediate tray. For the second side of double-sided/multiple printing, the transfer paper stored in the intermediate tray 202 is sent out one by one from the bottom by the paper feed roller 204 and guided to the registration roller 23 via the conveyance path 205.

In this embodiment, in such a configuration, analog exposure and digital exposure can be performed on the drum 1 either alternatively or simultaneously.

Next, the circuit configuration of the embodiment of the present invention will be explained. Second
The figure shows an example of the circuit configuration of the main parts in the embodiment of the present invention.

In FIG. 2, 500 is a main control circuit that controls the entire image forming apparatus.

Reference numeral 510 denotes a sequence control circuit consisting of various motors, sensors, and other equipment related to the copying shown in the first diagram.

A circuit 600 stores image information to be sent to the laser unit 13 and performs image processing such as gradation correction, and includes an image memory and a character generator. Reference numeral 900 is an external interface for inputting digital image information to be copied from the outside, and an R5232C or Centronics interface can be used.

A laser unit control circuit 800 turns on and off the laser unit 13, which will be described later, based on image information sent from the digital image control circuit 600. Reference numeral 1000 denotes an operation controller circuit section for manually inputting control information and other operation instruction information to the main control circuit 500, and has various input switches shown in FIG.

In such a configuration, the laser unit control circuit 800 performs laser beam exposure (digital exposure) based on the sent digital image.

Further, image information sent from an external device such as a host computer or a facsimile machine via the external interface circuit 900 is also stored in the digital image control circuit 600 and then recorded by the laser unit control circuit 800. The main control circuit 500 also controls the sequence control output unit 510 to perform analog exposure. Since the analog exposure control operation is well known, detailed explanation will be omitted.

FIG. 3 shows an example of the circuit configuration of the main control 500 circuit shown in FIG.

In FIG. 3, 501 is a 16-bit arithmetic processing unit (
cpu). 502 is a read only memory (ROM) in which a program related to this embodiment is stored. A random access memory (RAM) 503 serves as a storage memory for storing information regarding program operations. 504 is a two-bottom RAM for exchanging data with the operation unit controller 1000.

A 2-bot RAM 505 is used to receive data from the digital image controller 600. A communication controller 506 controls communication with unillustrated applications (document feeder, sorter, finisher, digitizer, etc.) provided as an option in the main body. 507 is an interface (Ilo). 51
Reference numeral 0 denotes a sequence controller input/output unit, which transfers signals relating to the operating status of each unit constituting the copying machine to the CPU via an interface 507. .

Reference numeral 550 denotes a high voltage control input/output unit, which includes control circuits for controlling high voltage output to the developing devices 14 and 15.

It should be noted that each of these control circuits is well known, so a detailed explanation will be omitted.

In the above configuration, the main control circuit 500 controls operations for analog exposure and digital exposure of the components of the copying machine. Control operations related to the present invention will be explained in detail later, but since the control procedures for each of analog exposure and digital exposure are well known, detailed explanations will be omitted.

FIG. 4 shows the digital image control circuit 60 shown in FIG.
0 shows an example of the circuit configuration. .

In Figure 4, 601 is 16-bit) CPII,
Performs image conversion processing, etc. related to digital images.

For this image conversion process, for example, a character code input from the external interface circuit 900 is converted into an image by the CGROM 605 and inputted to the image memory 604, or a specific character or a specific character code is input from the image memory 604 storing the image. The process of extracting specific information such as color and the extracted specific information are stored in add-on RAM 6.
CP0601 performs the process of storing the data to 06.

602 is a ROM in which a program executed by the G:Pu 601 is stored. A working RAM 603 temporarily stores variables used in the program. 604 is an image memory, and the image memory 604 directly outputs the image data read by the CCD image reading control circuit 900 to the laser unit control circuit 800.

Further, when accessing the digital control circuit 600 from the laser unit control circuit 800 side, access to the image memory 604 of the CPII 601 is prohibited.

In such a configuration, the digital image control circuitry performs storage of read images and image modification.

FIG. 5 shows an example of the circuit configuration of the laser unit control circuit 800 shown in the second figure.

In FIG. 5, 801 is a data read control circuit, which reads a digital image based on a vertical synchronization signal sent from the main controller 500.

Data is read from the controller 600. A horizontal synchronization clock generator 802 generates a clock signal based on a horizontal synchronization signal CD generated by a horizontally scanned laser beam, reads data according to the recording position while taking timing, and passes it through a shift register 805 to the laser beam. Drive circuit 806 is turned on/off. Furthermore, a horizontal line counter 803. A timing generation circuit 804 counts horizontal synchronization clocks and generates a timing signal for vertical synchronization according to the counting result.

A circuit 807 according to the present invention is an inversion processing unit that inverts a data signal according to an instruction from the main controller 500 after reading image data. The inversion processing section performs black and white inversion on the normal image. In addition, as will be described later, depending on the polarity of the toner used to develop the latent image formed on the drum 1, a laser may be turned on (image scan) at the position where the toner is to be placed, or vice versa. When turning on the laser (background scan) for a position that is not covered, the inversion processing unit 807 performs the following operations according to instructions from the main control circuit 500.
9. Switching between Image Scan and Background In this embodiment, the toner polarity for analog exposure and digital exposure is changed in order to use the drum 1 for both analog exposure and digital exposure. Therefore, in accordance with the selected exposure mode, in the reversal processing section 80,
By inverting the image, the developing unit 14. Exposure according to the toner polarity can be realized in any of Is.

FIG. 6 shows an example of the external appearance of the operating section control circuit.

In FIG. 6, 125 is an add-on key according to the present invention, which instructs to add a digital image to a part of an analog image. 126 is a switching key for switching between analog exposure and digital exposure according to the present invention. 127 is a switch for instructing recording of internal information such as periodic maintenance.

Reference numeral 101 denotes an asterisk (*) key, which is used in a setting mode when the operator sets binding substitution, or sets the size of document frame eraser. 102 is an all reset key, which is pressed to return to the standard mode. Reference numeral 103 denotes a preheating key, which is pressed to put the machine into a preheating state or cancel the preheating state. It is also pressed to return to standard mode from the auto-shutoff state.

A copy start key 104 is pressed to start copying. 105 is a clear/stop key; the clear key is used during standby, and the stop key is used during copying. Here, the clear key is pressed to cancel the set number of copies. It is also used to cancel * (asterisk) mode. Press the stop key to interrupt continuous copying. The copy operation will stop after the copy at the point in time is completed.

Numerical keys 106 are pressed to set the number of copies. It is also used to set the * (asterisk) mode. A memory key 107 instructs the user to register a mode to be used.

1011.109 is a copy density key, which is pressed when manually adjusting the copy density. 110 is the E key to automatically adjust the copy density according to the density of the original.
Or press to cancel AE (automatic density adjustment) and switch to manual mode.

Ill is a cassette selection key, which is pressed to select an upper cassette, a lower cassette, or a lower paper deck.

Also, if an original is set in RDF/DF, 8PS
(automatic paper selection device) can be selected.

Reference numeral 112 is a same size key, which is pressed to make a same size (original size) copy.

+13 is an auto-magnification key, which is pressed to automatically reduce or enlarge the original to match the specified copy paper size. 114 and 115 are zoom keys, 64-142%
Press to specify any magnification between . 116.
Reference numeral 117 is a constant magnification key, which is pressed to specify reduction or enlargement of the standard size.

A double-sided key 118 is pressed to make a double-sided copy from a single-sided original, a double-sided copy from a double-sided original, or a single-sided copy from a double-sided original. A binding key 119 is pressed to create a binding margin of a specified length on the left side of the transfer paper. 120 is a photo key, which is pressed when copying a photo original. Reference numeral 121 denotes a multiple key, which is pressed when forming images on the same side of transfer paper from two originals. Reference numeral 122 denotes a document frame erase key, which is pressed by the operator when erasing the frame of a standard size document, and the size is set using the * key 101.

123 is a sheet frame erase key, which is pressed to erase the frame according to the cassette size. Reference numeral 124 denotes a page continuous copying key, which is pressed when copying the left and right pages of a document on separate sheets.

128 is a sort key, which is lit in standard mode if the machine is equipped with a sorter. Press to cancel or enter sort mode. 129 is the group key, l
Make multiple copies from the original, and if it has a sorter, 1
The finisher 400 is stored in each bin, and the finisher 400 is stored in the oscillating copy tray 401 at different levels.

150 is an LCD (? night crystal) message display, each character is 5 x 7 dots, and has 40 characters. It is a transflective liquid crystal display with two colors for the backlight. Normally the backlight is green, but in the event of an error or when copying is not possible, the backlight turns orange. 151 is a magnification display, which displays the set magnification in %.

Reference numeral 152 indicates the same size display, which lights up when the same size is selected as the copy magnification. Reference numeral 153 is a color developer display, which lights up when a sepia developer is set. 154 is a copy number display which displays the number of copies or a self-diagnosis code. Reference numeral 155 indicates the cassette in use, which indicates which of the upper, middle, and lower cassettes or decks is selected.

156 is the original orientation display, which indicates the orientation of the original (portrait/
(horizontal). 157 is an AE display, which lights up when AE (automatic density adjustment) is selected.

158 is a preheating display, which lights up when in the preheating state.

Flashes when in auto shutoff mode. ! 59 is ready/wait indicator, green and orange LED
When ready (copy possible), the light is green, and when wait (copy is not possible), the light is orange. 16Q is a double-sided copy display, which lights up when either double-sided copying from a double-sided original or double-sided copying from a single-sided original is selected.

In standard mode, the number of copies is 1 in IIDFID.

Density AE mode, automatic paper selection, 11x9, single-sided original to single-sided copy settings. When RDF is not used, the settings are 1 copy, manual density mode, and 1-sided copying from a 1-sided original with 1x 0. The difference between when RDF is used and when it is not used is determined by whether or not a document is set in RDF.

Next, the developing units 14 and 15 according to the present invention will be explained. The first developing unit 14 and the second developing unit 15 shown in the first figure are configured to be replaceable as a unit. The first developer unit 14 is provided with a unit containing positive black toner and red, blue, green toner, and the second developer unit 15 is provided with a unit containing negative black toner and red, blue, ! A unit having i color toner is provided. When each unit is set, sensors 551 and 552 are activated and output signals indicating the toner type and polarity. This situation is shown in Table 1. The main controller 500 reads the type signal and polarity signal, and the developing DC bias is controlled according to the type signal and polarity signal. In addition,
The type signal sensors 551 and 552 (see FIG. 3) of each developing device have three pins on the connector portion of the developing unit (not shown), and can detect the toner used as shown in Table 1.

Table 1 This copying machine uses negatively charged toner to develop analog images and background scan digital images, and uses positively charged toner to develop imagescan digital images.

FIGS. 7 and 8 show schematic configuration examples of the developing device (second developing device) 15 for analog system and background scan digital system. This figure also shows the state of development using a single-component toner.

In FIG. 7, 9-1 is a fixed spherical magnet. 9-2 is a rotatable stainless steel cylinder arranged around the outer periphery of the magnet 9-1. 9-3 is a blade that guides the toner to the cylinder. -Component toner 9
The main components of the toner 9-4 are, for example, magnetic and resin, and the toner 9-4 has insulating properties and is negatively charged by friction with a rotating cylinder.

A concentrated magnetic field is constantly generated from the magnet 9-1 toward the tip of the blade 9-3, and this concentrated magnetic field is used to collect magnetic toner in this area. The toner collected by this concentrated magnetic field has a strong bond with the blade 9-3, so it hardly moves. A thin and uniform toner layer is formed on the cylinder 9-2 by the toner 9-4 having a strong binding force with the blade 9-3.

Cylinder 9-2 and blade 9-3 are biased to
1400V-18001Iz) and DC bias (140V-18001Iz)
Since V) is applied at the same time (this is called a developing bias), the positive component of the developing bias is greater than the negative component.

During copying, depending on the relationship between the strength of the electric field caused by the difference between the surface potential of the drum 1 and the potential of the cylinder 9-2 (that is, the developing bias) and the strength of the attraction between the toner 9-4 and the magnet 9-1 due to magnetic force. As a result, the toner 9-4 is attracted to the drum 1, and the attracted toner returns to the developing cylinder to turn the electrostatic tVI image into a visible image.

FIG. 9 shows a schematic configuration example of the image scan digital system developing device (first developing device) 14.

In FIG. 9, the basic 4M composition is the same as that of the analog developing device 15 shown in FIG. 7, but the material of the negative component toner is different and is positively charged due to friction.

The DC component of the developing bias is 280V.

When a latent image is formed on the drum 1 by an analog system or a background scan digital system, toner is not attracted to the area where the light hits, and when an image scan system image is formed on the drum 1, the light is not absorbed. The toner will stick to the area where it hits.

Next, the image transfer process in such a configuration will be described.

When developing with negatively charged toner, a positive corona is applied to the back side of the copy paper, and when the copy paper is fed to the drum 1 with the back side charged with a positive charge, a transfer charge (not shown) is generated. The toner on the surface of the drum 1 is transferred onto the copy paper by the device. When developing with positively charged toner, apply negative corona from the back side of the copy paper to charge the back side of the paper with a negative charge.
The toner on the drum surface is transferred to the copy paper.

Transfer 111 included in the high voltage control output section 500: The main control circuit 50 also controls the plus and minus of electrical appliances.
This is done by 0.

FIG. 1O shows the procedure for switching between digital development and analog development by the main control circuit 500.

In step 51 of FIG. 10, the main control circuit 500 determines whether analog image recording or digital image recording is to be performed, depending on the pressed state of the switching key 126 of the operation unit control circuit 1000. S2)
, After this determination, when the switching key is for digital image recording, the developing bias is set to 280V and the transfer charger is set to plus (+) (steps S3 and S4). When the instruction of the switching key is to record an analog image, the developing bias is set to 140V and the transfer charger is set to negative (-) (step 55, S6).

Next, within the process of one rotation of the drum in this embodiment, a digital latent image is added to the analog latent image, the analog latent image is developed in the second developing device 15, and the digital latent image is developed in the first developing device 14.
We will explain the so-called 1-shot add-on function that develops with .

FIGS. 11(A) and 11(B) show the image forming process. In FIGS. 11A and 11B, in the pre-exposure stage, residual charges on the surface of the drum 10 are erased before the secondary charging, thereby preventing copy density unevenness. In the next primary charging stage, the drum surface is uniformly charged to 800 V by a high voltage control circuit (not shown) by positive corona discharge. Thereafter, in the next document exposure step, the document on the document glass surface is reflected by the light from the halogen lamp 4, and an image is formed on the surface of the drum 1. At this time, the amount of light from the halogen lamp 4 is adjusted by the main control circuit 500 so that the surface potential of the drum becomes 450 V at the exposed portion (white portion). An analog latent image is formed on the drum 1 by performing these three stages of processing.

Next, in the laser exposure step, the laser beam is used to record digital images, i.e., laser Perform exposure.

The add-on section that records additional information switches the intensity of the laser light in two steps, and the off-toner part (white part) of the add-on section turns on the laser light so that the drum surface potential is about 430V, and the on-toner part (white part) For black or color toner (partially black or color toner), the laser beam is further strengthened, and the intensity of the laser beam is switched in two steps so that the drum surface potential becomes 50V or less. Control of these laser beams is performed by the laser unit control circuit 800 according to instructions from the main control circuit 500.

When the latent images of the analog image and the digital image are thus formed on the drum 1, the next step is to develop the digital image, that is, the add-on portion, using the developing device 14. By using a positively charged toner, the toner adheres to areas where the drum surface potential is low. For this purpose, a developing bias of 300 V AC+DC is applied. Then, the toner is attracted only to the portions of the drum 1 that are strongly illuminated by the laser. If a color toner, for example a red toner, is used in this development, the add-on portion will first be developed in red.

Next, the analog image is developed, that is, the exposed portion of the original is developed by the developing device 15. Developing bias ^C+DC58
If the voltage is set to 0V and a negatively charged toner is used, the toner will adhere to areas of the drum 1 where the surface potential is high.

After the toner corresponding to the image is deposited on the drum l in this way, the copy paper is sent, and the image developed by the negative corona discharge by the transfer charger 16 is transferred onto the copy paper. The copy paper is attracted to the surface of the drum 1 by static electricity, but in the next step, a DC bias is applied to the drum 1 and the copy paper is transferred to the drum 1 by corona discharge.
Separate from. Finally, a cleaner plate (not shown)
The residual toner on the surface of the drum 1 is scraped off to complete one recording operation.

Next, an example of use of this embodiment will be explained using FIG. 12 and FIG. 13.

This embodiment is intended to output internal information for maintenance personnel during periodic maintenance and the like. FIG. 12 shows an example of the internal information.

When maintenance personnel turn on the service information print switch 127, the number of used transfer sheets, the number of jams, etc. are output as shown in FIG.

FIG. 13 shows an example of a control procedure of the main control circuit 500 for recording internal information.

In FIG. 13, the digital image control circuit 60
0 When the ON information of the service information print switch 127 is input manually, the CPU of the main control circuit 500
501 issues a service print instruction.

Upon receiving this instruction, the digital image control circuit 600 initializes the image memory 604 for service printing (step 5ll). Next, when the CPO 501 issues an instruction regarding a header (heading), the digital image control circuit 600 develops the heading information in the form of image data in the image memory 604 (step 51).
3). Next, in steps 513 to S15, each data is transferred to the digital image control circuit 600 from the two-bottom RAM 50.
Send via 5. If there is information to be notified, such as input information, in addition to the standard information, the CPU 501 transfers the contents to the digital image control circuit in the form of a code. Printing begins when all information is in place (step 518). For this printing, paper feeding is normally started using sequence control, and when paper feeding is completed, a vertical synchronization signal is output to the laser unit control circuit 800.
After that, the registration roller is turned on at the correct timing to complete the process.

[Effects of the Invention] As explained above, according to the present invention, a toner for developing a latent image formed on a photosensitive device by a first exposure device that performs analog exposure, and a second exposure device that performs digital exposure. Since the polarities of the toners used to develop the latent image formed on the photosensitive means are made different, the area exposed by the second exposure means can be used as an image to be recorded. The second exposure means no longer needs to perform backscanning. As a result, the exposure time of the second exposure means is also shortened, resulting in the effect that the life of the second exposure means can be extended.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a schematic configuration of an embodiment of the present invention, FIG. 2 is a block diagram showing an example of a circuit configuration of an embodiment of the present invention, and FIG. 3 is a configuration of the main control circuit 500 shown in FIG. 1. A block diagram showing an example, FIG. 4 is a digital image control circuit 60 shown in FIG.
FIG. 5 is a block diagram showing an example of the configuration of the laser unit control circuit 800 shown in FIG. , FIGS. 7 to 9 are schematic diagrams showing the developing principle of the developing device 14 and 15 shown in FIG. 1, and FIG. 10 is a main control circuit 60 of the embodiment of the present invention.
Flowchart showing an example of the control procedure of 0, FIG.
A) and ([l) are explanatory diagrams showing the development process of digital images and analog images according to the embodiment of the present invention; FIG. 12 is an explanatory diagram showing a printing example of the embodiment of the present invention;
The figure is a flowchart showing an example of a control procedure regarding internal information printing according to an embodiment of the present invention. 500... Main control circuit, 600... Digital image control circuit, 800... Laser unit control circuit, 900... External interface circuit, 1000... Operating unit control circuit. This figure shows the force λ, the tq figure. 7 Figure 4 (Metsu Akira * sickle I row θ gise, I elephant path 150 I 乍 dekakado ring (sheep - [Saishara style "Giant 1 8 Figure 1 Ku plane sun moon large ° direction, I row η Otsui sect 3614 no I
fJ The origin of the origin diagram Figure 9 Flowchart Figure 10 Flowchart Figure 10
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Claims (1)

[Scope of Claims] 1) a photosensitive means that forms a latent image by exposure; a first exposure means that exposes and scans a document image on the photosensitive means via an optical system; a second exposure means for performing exposure scanning of an image; and a second exposure means for developing a latent image formed on the photosensitive means by the first exposure means with a first toner having a first polarity;
a developing means for developing a latent image formed on the photosensitive means by the second exposing means with a second toner having a second polarity different from the polarity of the copying machine.