JP2007017850A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform the addition of developing colors without performing the change of apparatus size such as the increase in the number of developing devices. <P>SOLUTION: Developing devices 5 to 8 in which toners of the four colors of K, Y, C, M as common colors are set, respectively, are composed freely attachably/detachably. Then, in the case printing colors are added as well as the ordinary colors, and image forming treatment is performed, developing devices corresponding to the additional colors and the developing devices 5 to 8 are exchanged, and the image forming treatment is performed, and images formed on an intermediate transferring belt 13 are superposed. After the completion of the intermediate transferring treatment by the additional colors, the transfer of the images from the intermediate transferring belt 13 to paper is performed. In this way, even in the case the other printing colors are added as well as the common colors, and the image forming treatment is performed, by composing the existent developing devices freely attachably/detachably, and exchanging the developing devices corresponding to the additional colors, the apparatus can easily cope with the case without performing the change of the apparatus such as the increase in the number of developing devices. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using an electrophotographic system, such as an electronic copying machine or a printer, and more particularly to an image forming apparatus capable of forming a color image.

In the case of forming a color image in an image forming apparatus using an electrophotographic system, a developing device in which toners for developing four colors of yellow, magenta, cyan, and black are set is generally provided. Then, the image data of each color is transferred onto the photosensitive member, and the color is superimposed on the intermediate transfer member to form a color image.
Conventionally, in such an image forming apparatus, in order to form a color image with higher image quality, a technique for forming an image by superimposing different colors on the commonly used colors yellow, magenta, cyan, and black is described below. Various disclosures are made in the patent literature.
JP 2004-258512 A JP 2004-219613 A JP-A-8-171252

  Patent Documents 1 and 2 disclose tandem type image forming apparatuses in which image forming units in which yellow, magenta, cyan, black, and special color toners are set are arranged in parallel to each other. The special color toners include toners of colors that are difficult or impossible to express with the four colors of yellow, magenta, cyan, and black, and braille firing toner and fluorescent color toner.

  Patent Document 3 discloses a drum type in which black is divided into a highlight density and a dark density, and development units including yellow, magenta, cyan, highlight density black, and dark density black are provided on the developing drum. An image forming apparatus is disclosed. The density of the highlight density black is set to about ½ of the density of the dark density black.

When image formation is performed by adding colors in addition to the usual colors of yellow, magenta, cyan, and black, as shown in Patent Documents 1 to 3, the color developing devices for increasing colors are added. There is a need to.
When the developing devices are added, not only the image forming apparatus is increased in size but also the production cost is increased.
SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can add a development color in an image forming process without changing the apparatus size such as increasing the number of developing devices.

  According to the first aspect of the present invention, the first transfer means for transferring the first toner image formed by the detachable first developing device to the transfer body, and the first transfer means for the first toner image. After the toner image is transferred to the transfer body, the second toner image formed by the detachable second developing device provided at the position where the first developing device is provided is transferred. Second transfer means for transferring to a body, and image forming means for transferring the first toner image and the second toner image superimposed on the transfer body to a recording medium to form an image. The object is achieved by providing.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the first developing device includes four color developing devices of cyan, magenta, yellow, and black.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the first development is performed after the first toner image is transferred to the transfer body by the first transfer unit. Display means for prompting the operator to replace the developer with the second developer.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the first, second, or third aspect, a detection unit that detects whether or not the second developing unit is correctly disposed; Warning means for issuing a warning when the two developing devices are not correctly disposed.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the first developing unit and the second developing unit have a storage device storing information for identifying the color of the developing unit. The detecting means detects whether or not the second developing device is correctly arranged based on the information stored in the storage device.

According to the first aspect of the present invention, since the first developing device and the second developing device can be exchanged, the image forming process can be performed without changing the apparatus size such as increasing the number of developing devices. Development color can be added.
According to the second aspect of the present invention, it is possible to easily superimpose four or more colors that are commonly used colors.
According to the invention described in claim 3, by providing the display means, it is possible to prompt the operator to replace the first developing device and the second developing device appropriately.

According to the fourth aspect of the present invention, it is possible to suppress the occurrence of erroneous image forming processing by detecting whether or not the second developing device is properly disposed and issuing a warning when the second developing device is not correctly disposed. Can do.
According to the fifth aspect of the present invention, by providing each developing device with a storage device that stores information for identifying the color of the developing device, the detection processing in the detecting means is facilitated.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS.
FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus according to the present embodiment.
In this embodiment, a tandem type color laser printer apparatus including an intermediate transfer belt as an intermediate transfer member will be described as an example of an image forming apparatus.
For example, an endless photoreceptor belt 1 is used as a photoreceptor as an image carrier. The photosensitive belt 1 is stretched around a plurality of rollers 2, and one of the plurality of rollers 2 is rotationally driven by a driving source (not shown), so that the photosensitive belt 1 is rotationally driven in the arrow direction. .

When the color image forming mode is selected in the operation unit and the start key is pressed, the photosensitive belt 1 is uniformly charged by the charging brush 3 to which a charging voltage is applied from a high voltage power source (not shown).
After that, the writing unit (writing device) 4 is first exposed with a light beam modulated by a black (hereinafter referred to as K) image signal to form an electrostatic latent image (hereinafter referred to as a K latent image) corresponding to the K image signal. .

The K developing unit 5, the yellow (hereinafter referred to as Y) developing unit 6, the cyan (hereinafter referred to as C) developing unit 7 and the magenta (hereinafter referred to as M) developing unit 8 are each moved to the developing position by the contact / separation mechanisms 9 to 12 during development. At the time of non-development, the contact / separation mechanisms 9 to 12 retreat from the development position and return to the home position, and are separated from the photosensitive belt 1. The K latent image on the photoreceptor belt 1 is developed with K toner by the K developing device 5 to become a K toner image.
On the other hand, an endless intermediate transfer belt 13 as an intermediate transfer member is stretched over a plurality of rollers 14 to 16 and brought into contact with the photosensitive belt 1, and one of the plurality of rollers 14 to 16 is not shown. By being driven to rotate by the drive source, the intermediate transfer belt 13 rotates in the direction of the arrow at the same peripheral speed as the photosensitive belt 1.

A primary transfer brush 17 as a primary transfer unit is in contact with the intermediate transfer belt 13 at a primary transfer portion where the intermediate transfer belt 13 abuts on the photosensitive belt 1 and a transfer voltage is applied from a power source (not shown). And the K toner image on the photosensitive belt 1 is transferred to the intermediate transfer belt 13.
The photoreceptor belt 1 is cleaned by the photoreceptor cleaning device 18 after the transfer of the K toner image, and the charge is uniformly removed by the charge eliminating brush 19.

Next, after the photoreceptor belt 1 is uniformly charged by the charging brush 3, the photosensitive belt 1 is exposed to a light beam modulated by the Y image signal in the writing unit 4, and an electrostatic latent image (hereinafter referred to as the Y image signal). Y latent image) is formed.
The Y latent image on the photosensitive belt 1 is developed with Y toner by the Y developing device 6 to become a Y toner image. The Y toner image on the photosensitive belt 1 is intermediated by the primary transfer brush 17 in the primary transfer portion. The toner image is transferred onto the transfer belt 13 so as to overlap with the K toner image.
The photoconductor belt 1 is cleaned by the photoconductor cleaning device 18 after the transfer of the Y toner image, and is uniformly discharged by the charge eliminating brush 19.

Next, after the photoreceptor belt 1 is uniformly charged by the charging brush 3, the photosensitive belt 1 is exposed to a light beam modulated by the C image signal in the writing unit 4, and an electrostatic latent image corresponding to the C image signal (hereinafter, referred to as the electrostatic image). C latent image) is formed.
The C latent image on the photosensitive belt 1 is developed with C toner by a C developing unit 7 to be a C toner image, and the C toner image on the photosensitive belt 1 is intermediated by a primary transfer brush 17 in a primary transfer portion. The K toner image and the Y toner image are transferred onto the transfer belt 13 so as to overlap.
The photoreceptor belt 1 is cleaned by the photoreceptor cleaning device 18 after the C toner image is transferred, and is uniformly discharged by the charge removing brush 19.

Next, the photosensitive belt 1 is uniformly charged by the charging brush 3 and then exposed to a light beam modulated by the M image signal in the writing unit 4 to correspond to the electrostatic latent image (hereinafter referred to as the M image signal). M latent image) is formed.
The M latent image on the photosensitive belt 1 is developed with M toner by the M developing unit 8 to become an M toner image. The M toner image on the photosensitive belt 1 is intermediated by the primary transfer brush 17 in the primary transfer portion. By transferring the K toner image, the Y toner image, and the C toner image on the transfer belt 13 in an overlapping manner, a four-color superimposed color image is formed on the intermediate transfer belt 13.
The photoreceptor belt 1 is cleaned by the photoreceptor cleaning device 18 after the M toner image is transferred, and is uniformly discharged by the charge eliminating brush 19.

In the image forming apparatus according to the present embodiment, the above-described K developing unit 5, Y developing unit 6, C developing unit 7, and M developing unit 8 are configured to be detachable, and are connected to developing units of other colors. Replacement (exchange) is possible.
When an image is formed by superimposing toner images formed of eight colors of K, Y, C, M, for example, eight colors, that is, when the print color addition mode is selected, the operator , K developing unit 5, Y developing unit 6, C developing unit 7, and M developing unit 8 are replaced with developing units of added colors. This replacement work is performed after the development processing in the K developing unit 5, the Y developing unit 6, the C developing unit 7, and the M developing unit 8 is completed.

When the developing device is replaced with the added color developing device, the photosensitive belt 1 is uniformly charged by the charging brush 3 and then the light beam modulated by the image signal of the added color in the writing unit 4. The electrostatic latent image corresponding to the image signal of the color added by exposure is formed.
The added color latent image on the photosensitive belt 1 is developed with the added color toner by the replaced developing device, and becomes an added color toner image. The added color toner image on the photosensitive belt 1 is transferred onto the intermediate transfer belt 13 by the primary transfer brush 17 on the intermediate transfer belt 13 by being transferred onto the intermediate transfer belt 13 by the primary transfer brush 17. A color image in which four colors and additional colors are superimposed on each other is formed.
The photosensitive belt 1 is cleaned by the photosensitive member cleaning device 18 after the toner image of the added color is transferred, and is uniformly discharged by the discharging brush 19.

The sheet feeding device 20 feeds the sheet to the registration roller 21, and the registration roller 21 sends the sheet to the secondary transfer unit in accordance with the color image on the intermediate transfer belt 13.
In this sheet, the color image on the intermediate transfer belt 13 is transferred by the secondary transfer unit 22 in the secondary transfer unit, and the color image is fixed by the thermal fixing unit 23. The paper is discharged to the paper discharge tray.
The secondary transfer device 22 operates by contacting the intermediate transfer belt 13 at the secondary transfer portion and applying a transfer voltage from a power source (not shown).

At the time of double-sided image formation, the paper that has passed through the thermal fixing device 23 is fed to the registration roller 21 with the front and back being reversed by the double-sided device 25, and the secondary transfer unit matches the color image on the intermediate transfer belt 13 by the registration roller 21. Sent out.
In the secondary transfer unit, the color image on the intermediate transfer belt 13 is transferred to the back surface by the secondary transfer device 22, the color image on the back surface is fixed by the thermal fixing device 23, and the discharge roller 24 discharges the upper portion of the apparatus. It is discharged to the paper tray.
A paper conveyance monitoring sensor 27 is provided in the vicinity of the registration roller 21 to monitor the paper passing between the registration rollers 21.
The intermediate transfer belt 13 is cleaned by the cleaning device 26 after the color image is transferred.

Note that when a monochrome image forming mode is selected on the operation unit and the start key is pressed, a monochrome image forming process is performed.
In this case, the writing unit 4 writes on the photosensitive belt 1 with monochromatic image data to form an electrostatic latent image, and this electrostatic latent image is developed by one of the developing devices 5 to 8. After that, the image is transferred onto the intermediate transfer belt 13. The single-color toner image on the intermediate transfer belt 13 is transferred to a sheet by the secondary transfer device 22, and the toner image is fixed on the sheet by the thermal fixing device 23 and is discharged to a discharge tray.

FIG. 2 is a diagram showing a part of the electrical system of the image forming apparatus according to the present embodiment.
The CPU 30 as the control means executes various arithmetic processes and controls between other blocks.
The memory 31 is, for example, a storage device for information such as counter values. The CPU 30 executes information writing and reading (reading) processing on the memory 31.
The writing unit 32 performs writing on the photosensitive belt 1 and outputs it in response to a write signal output control command from the CPU 30.

The developing unit 33 creates an image by placing toner on the photosensitive belt 1 under the control of the CPU 30. The developing unit 33 has a function of writing (transferring) the color data (color information) of the currently set toner to the CPU 30.
The intermediate transfer unit 34 performs image transfer from the photosensitive belt 1 to the intermediate transfer belt 13 under the control of the CPU 30. The transferred color images are superimposed on the intermediate transfer belt 13.

The secondary transfer unit 35 transfers an image from the intermediate transfer belt 13 to a sheet under the control of the CPU 30.
The fixing unit 36 fixes the image on the paper under the control of the CPU 30.
The display / input unit 37 displays various information and messages under the control of the CPU 30. The display / input unit 37 has a function of accepting various inputs from the operator.

Next, the operation of the image forming process in the image forming apparatus configured as described above will be described.
FIG. 3 is a flowchart showing the procedure of the image forming process in the image forming apparatus according to the present embodiment. In the present embodiment, a case will be described in which a print instruction for color image data created by a PC device connected to the image forming apparatus is given. A printer driver, which is software for controlling the image forming apparatus, is installed in the PC device in advance.
Here, it is assumed that a “print color addition mode” is used in which printing is performed with eight color data on the printer driver when a print instruction is issued from the PC device.

First, the image forming apparatus accepts a print instruction specifying a “print color addition mode” for performing image forming processing with eight color data during printing (image formation) from the PC device (step 300).
The CPU 30 reads out and starts a print color addition print program for executing a print process (image formation process) corresponding to the “print color addition mode” from the memory 31.
Next, the CPU 30 clears the order counter that counts the order in which the number of developer replacements in the image forming process is (step 301). This order counter is stored in the memory 31.

The CPU 30 determines whether a print (start) request transmitted from the PC device has been received (step 302).
If a print (start) request has not been received (step 302; N), the CPU 30 continues to wait for a print (start) request transmitted from the PC device.
On the other hand, when a print (start) request is received (step 302; Y), the CPU 30 clears a color counter that counts colors to be developed (step 303).
Next, the CPU 30 controls the writing unit 32 to execute the writing process of the photosensitive belt 1 (step 304).
Subsequently, the CPU 30 controls the developing unit 33 and executes a developing process for creating an image by placing toner on the photosensitive belt 1 (step 305).

The CPU 30 controls the intermediate transfer unit 34 to execute an intermediate transfer process for transferring an image from the photosensitive belt 1 to the intermediate transfer belt 13 (step 306).
When a series of processing in steps 304 to 306 is completed, the color counter that counts the color to be developed is updated (step 307). That is, 1 is added to the color counter.
Next, the CPU 30 determines whether or not the color counter value is 4 (step 308).
If the color counter value is less than 4 (step 308; N), that is, if the intermediate transfer process using four colors is not completed, the process returns to step 304 and the processes for the remaining colors are repeated.

On the other hand, when the color counter value is 4 (step 308; Y), that is, when the intermediate transfer process with four colors is completed, the CPU 30 updates the forward counter (step 309). That is, 1 is added to the forward counter.
Next, the CPU 30 determines whether or not the forward counter value is 2 (step 310). That is, it is determined whether the developing unit has been replaced and the intermediate transfer process using the additional color has been completed.
When the forward counter value is not 2 (step 310; N), that is, when the operator has not replaced the developing device, the CPU 30 stops the image forming process, and the display / input unit 37 receives a message from the PC device. Based on the print request, the instruction contents such as the position and color of the developing device (developing unit) of the next color to be superimposed are displayed (step 400).

Next, the CPU 30 detects the state of the developing unit 33 and determines whether or not the replacement of the developing device by the operator has been completed as instructed (step 401).
Each developing device (developing unit) is provided with a memory in which color data capable of identifying the color of the toner set in the developing device is stored.
The developing unit 33 is configured to refer to the color data stored in the memory and to transfer the reference result to the CPU 30.
The CPU 30 detects the state of the developing unit 33 based on the transferred reference result (color data) and the like.

When the replacement of the developing device is not completed as instructed (step 401; N), the CPU 30 displays an alarm process such as displaying a message (warning) for prompting the replacement of the developing device as instructed or generating a warning sound. Is executed (step 402), and the process of step 400 is repeated again.
On the other hand, when the replacement of the developing device has been completed as instructed (step 401; Y), the processing returns to step 303, and the processing with the color of the replaced developing device, that is, the additionally designated color is repeated.
Note that after the second order, it is not always necessary to perform the image forming process four times, and the image forming process corresponding to the additionally designated number of colors is performed. In other words, the print color is automatically created by the printer driver when a print instruction is given, so it is sufficient to create as many images as the number of added colors.

If it is determined in step 310 that the forward counter value is 2 (step 310; Y), that is, if the developing device is replaced and the intermediate transfer process using the additional color is completed, the CPU 30 performs the secondary transfer. The unit 35 is controlled to perform a sheet transfer process for transferring an image from the intermediate transfer belt 13 to the sheet (step 311).
Next, the CPU 30 controls the fixing unit 36 to execute a fixing process for fixing an image on a sheet (step 312), and ends a series of image forming processes.

The number of colors that can be added in the print color addition mode can be set to an arbitrary value. When the number of additional colors exceeds five, it can be dealt with by adding the number of replacements of the developing device according to the additional colors.
In the present embodiment, it is assumed that image formation processing is performed with eight colors, that is, four colors are added to four colors K, Y, C, and M. Therefore, the determination setting value of the color counter is 4 and the determination setting value of the forward counter is 2, but the determination setting value of the color counter and the determination setting value of the forward counter change according to the number of added colors. It is. However, since the colors are fixed to the four colors K, Y, C, and M, which are commonly used colors, the determination setting value of the color counter is set to 4 in principle.

If the “printing color addition mode” is not selected (set) and the “normal mode” in which the image forming process using only the regular colors is performed, the color counter value becomes 4 (step 308; Y) The paper transfer process in step 311 and the fixing process in step 312 are immediately executed, and the image forming process is terminated.
That is, only when the “print color addition mode” is designated, the image formation is temporarily stopped and the developing device is replaced.
The contents displayed by the display process on the display / input unit 37 in step 400 are preferably received as commands from the PC device via the printer driver.
Further, the confirmation of completion of developing device replacement may be made by displaying a “replacement completion button” on the display / input unit 37 and allowing the operator to operate the button after the work is completed.

  According to the present embodiment, when image formation is performed by superimposing four or more colors K, Y, C, and M, which are common colors, that is, an image is formed by adding a print color in addition to the regular colors. Even in the case of processing, the existing developer can be configured to be detachable, and the developer corresponding to the additional color can be easily replaced without changing the device such as increasing the number of developers. Can respond.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an exemplary embodiment. FIG. 2 is a diagram illustrating a part of an electrical system of the image forming apparatus according to the present embodiment. 5 is a flowchart showing a procedure of an image forming process in the image forming apparatus according to the present embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor belt 2 Roller 3 Charging brush 4 Writing part 5 K developing device 6 Y developing device 7 C developing device 8 M developing device 9-12 Contact / separation mechanism 13 Intermediate transfer belt 14-16 Roller 17 Primary transfer brush 18 Photoconductor Cleaning device 19 Static elimination brush 20 Paper feeding device 21 Registration roller 22 Secondary transfer device 23 Thermal fixing device 24 Paper discharge roller 25 Double-sided device 26 Cleaning device 27 Paper transport monitoring sensor 30 CPU
31 Memory 32 Writing unit 33 Developing unit 34 Intermediate transfer unit 35 Secondary transfer unit 36 Fixing unit 37 Display / input unit

Claims (5)

First transfer means for transferring a first toner image formed by a detachable first developer to a transfer member;
After the first toner image is transferred to the transfer body by the first transfer unit, the first toner image is formed by a removable second developing device disposed at a position where the first developing device is disposed. A second transfer means for transferring the imaged second toner image to the transfer body;
Image forming means for transferring the first toner image and the second toner image superimposed on the transfer body to a recording medium to form an image;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the first developing unit includes four color developing units of cyan, magenta, yellow, and black.   Display means for prompting an operator to replace the first developer unit with the second developer unit after the first toner image is transferred to the transfer member by the first transfer unit. The image forming apparatus according to claim 1, further comprising: Detecting means for detecting whether or not the second developing device is correctly disposed;
Warning means for issuing a warning when the second developer is not correctly disposed;
The image forming apparatus according to claim 1, 2, or 3. The first developing unit and the second developing unit each have a storage device that stores information for identifying the color of the developing unit,
The image forming apparatus according to claim 4, wherein the detection unit detects whether or not the second developing device is correctly arranged based on information stored in the storage device.

Images