JP2007155824A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and an image forming method which enable a color image to be inexpensively formed and a high-quality color image to be formed as necessary. <P>SOLUTION: The tandem type image forming apparatus 1 is equipped with a plurality of image forming units 10, and forms the color image by multiple transferring of respective color toner images formed by the respective image forming units 10 to a body to be transferred, thereby forming the color image. The apparatus 1 is equipped with four or more housing parts 6 for housing the image forming units 10, and performs an image forming mode in which the color image is formed by using only the first to the third image forming units 10 as the plurality of image forming units 10 when the first image forming unit 10 for magenta is housed in the first housing part 6, the second image forming unit 10 for cyan is housed in the second housing part 6 and the third image forming unit 10 for black is housed in the third housing part 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus and an image forming method.

Generally, a tandem image forming apparatus includes image forming units for yellow, cyan, magenta, and black colors arranged along a transfer belt, and generates four color toner images formed by the respective image forming units. Then, the image is transferred onto a transfer belt or a recording sheet conveyed by the transfer belt, and a color image is formed by subtractive color mixing. Since such an image forming apparatus can form a color image with a single sheet passing, the image forming process is performed at high speed.
Editor Electrophotographic Society “Continued Fundamentals and Applications of Electrophotographic Technology” Published by Corona Co., Ltd. November 15, 1996 55

In recent years, the image quality of color images formed by image forming apparatuses has been remarkably improved. However, there are not always many environments where a high-quality color image is always required. If a high-quality color image is obtained only when necessary, a low-quality color image can be reduced at other times. There is also a user need that a cost is preferable.
SUMMARY OF THE INVENTION In view of the above-described problems, the present invention has an object to provide an image forming apparatus and an image forming method capable of forming a color image at a low cost and also capable of forming a high-quality color image as necessary. To do.

  In order to achieve the above object, an image forming apparatus according to the present invention includes a plurality of image forming units, and performs color transfer by multiple-transferring toner images of respective colors formed by the respective image forming units onto a transfer target. An image forming apparatus of a tandem method for forming an image, comprising four or more storage units for storing image forming units, wherein the first image forming unit for magenta color is stored in the first storage unit, When the second image forming unit for cyan is stored in the second storage unit and the third image forming unit for black color is stored in the third storage unit, the plurality of image forming units The image forming mode for forming a color image is executed using only the first to third image forming units.

  In this way, if it is possible to form a color image with three colors of magenta, cyan, and black, it is possible to reduce the cost by the amount of toner to be used, compared to the case of using four colors including yellow. . At least one empty storage unit is provided. For example, when a yellow image forming unit is attached to the empty storage unit by a user, four color forming units are used by using four image forming units. If configured so as to form an image, the user can selectively enjoy the effect of obtaining a high-quality image of four colors and the effect of reducing the cost of three colors.

In a specific aspect of the image forming apparatus according to the present invention, each of the first to third image forming units is configured to be detachable from the first to third storage units.
In this way, the user can replace the first to third image forming units in units, and the replacement work is simplified.
In a specific aspect of the image forming apparatus according to the present invention, a fourth image forming unit different from the first to third image forming units is provided in the fourth different from the first to third storage units. It is comprised so that attachment or detachment is possible with respect to the storage part.

In this way, the fourth image forming unit can also be replaced in units. Furthermore, there are many combinations of image forming units, and combinations that are more suitable for the usage environment are possible.
In a specific aspect of the image forming apparatus according to the present invention, the fourth image forming unit is one for magenta color, cyan color, and black color, and the fourth storage unit includes a fourth image forming unit. In the case where image forming units are stored, a plurality of image forming units for the same color are used by switching them.

In this way, a plurality of frequently used color image forming units can be mounted, and the number of unit replacements can be reduced to save maintenance work.
Further, in a specific aspect of the image forming apparatus according to the present invention, the color is developed using one image forming unit among the plurality of image forming units for the same color, and the one image forming unit is used. When development is impossible, the color is developed by switching to another image forming unit.

  In this way, when the development by the one image forming unit becomes impossible, it is possible to know that it is necessary to prepare an alternative image forming unit, and the development by another image forming unit can be performed. While performing, it is possible to prepare an image forming unit that replaces the one image forming unit that cannot be developed, or to replace it. Accordingly, it is difficult for image formation to be interrupted due to the image forming unit.

In a specific aspect of the image forming apparatus according to the present invention, the plurality of image forming units for the same color are alternately switched.
In this way, it is easy for a plurality of image forming units for the same color to shift to a state in which development is impossible at substantially the same time, and it becomes possible to perform unit replacement and the like all at once. Can be reduced.

In a specific aspect of the image forming apparatus according to the present invention, the transfer target is a recording sheet, and an image forming unit to be used is switched for each sheet.
In this way, since one image forming unit is used for one sheet, the image is not disturbed due to a shift or the like caused by switching the units.
Further, in a specific aspect of the image forming apparatus according to the present invention, the transfer target is a sheet for recording, and when the image forming area for one sheet is divided into a plurality of partial areas, each partial area The image forming unit to be used is switched every time.

In this way, the toner can be more evenly consumed for a plurality of image forming units for the same color, and each unit can easily shift to a state in which development is impossible at the same time.
In a specific aspect of the image forming apparatus according to the present invention, the color image is formed in units of jobs, and the image forming unit to be used is switched for each job.

In this way, the switching control of the image forming unit can be simplified.
Further, in a specific aspect of the image forming apparatus according to the present invention, a selection input of the usage method is received for the plurality of imaging units for the same color, and the imaging unit to be used based on the received usage method It is characterized by switching.
In this way, for example, the user can use different desired usage methods.

  In a specific aspect of the image forming apparatus according to the present invention, the fourth image forming unit for yellow color is configured to be detachable from a fourth storage unit different from the first to third storage units. When the fourth image forming unit is stored in the fourth storage unit, the first to fourth image forming units are used instead of the image forming mode, and a color image is displayed. Another image forming mode to be formed is executed.

In this way, it is possible to form a low-cost color image with three colors of magenta, cyan, and black, and if necessary, a high-quality full-color image with four colors of yellow, magenta, cyan, and black can also be formed. become.
Further, in a specific aspect of the image forming apparatus according to the present invention, waste toner collection for collecting residual toner on the one image carrier in a fourth storage unit different from the first to third storage units. The unit is configured to be detachable.

In this way, the residual toner on the image carrier can be collected by the waste toner collecting unit, so that the image quality is further improved.
In a specific aspect of the image forming apparatus according to the present invention, a cleaner that collects residual toner on the one image carrier is provided at a position different from each of the storage units, and the fourth storage unit includes the cleaner. When the waste toner collecting unit is stored, the cleaner and the waste toner collecting unit are switched and used.

In this way, the residual toner can be collected by both the cleaner and the waste toner collecting unit, and the removal function becomes higher.
Further, in a specific aspect of the image forming apparatus according to the present invention, during the residual toner collecting operation by the cleaner, the residual toner collecting unit by the waste toner collecting unit is stopped and the residual toner is collected by the cleaner. When it becomes impossible, the waste toner collecting unit starts the residual toner collecting operation.

In this case, since the residual toner is mainly collected by the cleaner, it is difficult to cause trouble even if the waste toner collecting unit is replaced with the image forming unit.
In a specific aspect of the image forming apparatus according to the present invention, the cleaner and the waste toner collecting unit are alternately switched and used.
In this way, the cleaner and the waste toner collecting unit are likely to be saturated so that they cannot be collected at substantially the same time. For example, the user performs an operation of removing the toner collected by the cleaner and the waste toner collecting unit. In this case, the work can be performed once for the cleaner and the waste toner collecting unit, and maintenance work can be reduced.

Further, in a specific aspect of the image forming apparatus according to the present invention, a selection input of a usage method of the cleaner and the waste toner recovery unit is received, and the cleaner and the waste toner recovery unit are switched according to the received usage method. It is characterized by that.
In this way, the user can appropriately switch the usage method according to the usage situation, so that the usability is improved.

  In a specific aspect of the image forming apparatus according to the present invention, the magenta image forming unit includes a magenta for full color used when a color image is formed with four colors of magenta, cyan, yellow, and black. The pseudo full-color magenta toner in which the chromaticity point on the chromaticity diagram is shifted in a direction approaching the hue of yellow is stored, and / or the cyan image forming unit includes magenta, Compared to the full-color cyan toner used when forming a color image with four colors of cyan, yellow, and black, the chromaticity point on the chromaticity diagram is shifted in the direction approaching the hue of yellow. It is characterized by containing toner.

In this way, even a color image formed only with magenta, cyan, and black image forming units has an image quality close to that of a full-color image formed with four color image forming units of yellow, magenta, cyan, and black. Color images can be formed.
Further, in a specific aspect of the image forming apparatus according to the present invention, before the color image is formed, each combination of image forming units capable of forming a color image in the stored image forming units is combined with the combination. A corresponding image forming mode is obtained, and information indicating the obtained image forming mode is output.

In this way, the user can know an image forming mode that can be executed before image formation, and can form an image by a method suitable for the purpose of use in consideration of image quality and cost.
Further, in a specific aspect of the image forming apparatus according to the present invention, when a designation of what the user desires is received from among the image forming modes indicated in the output information, the designation is made instead of the image forming mode. An image forming mode is executed.

In this way, the user can form an image in the image forming mode desired by the user.
In a specific aspect of the image forming apparatus according to the present invention, the designation is accepted when there are a plurality of image forming modes indicated in the output information, and the designation is accepted in one case. The one image forming mode is executed instead of the image forming mode.

In this way, when there is no room for selection in the image forming mode, there is no time for waiting for the user's designation, so that an image can be formed more quickly and without trouble.
Further, in a specific aspect of the image forming apparatus according to the present invention, when the obtained image forming mode is one, the output is not performed and the one image forming mode is executed instead of the image forming mode. It is characterized by doing.

In this way, the control related to the output can be omitted, and the control can be simplified.
The image forming method according to the present invention sequentially forms toner images of different colors on a single image carrier using a plurality of image forming units, and multiplex-transfers the formed toner images onto a transfer medium. The first image forming unit for magenta color in the first storage unit among the four or more storage units for storing the image forming unit. Are stored, the second storage unit stores the cyan second image forming unit, and the third storage unit stores the black third image forming unit. An image forming mode for forming a color image is executed using only the first to third image forming units as the image forming units.

  In this way, the cost can be reduced by the amount of toner to be used, compared to the case of using four colors including yellow. For example, when a yellow image forming unit is installed in an empty storage unit, the effect of obtaining a high-quality image with four colors and the effect of reducing the cost with three colors can be selectively enjoyed. It becomes possible to do.

Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.
<First Embodiment>
(1) Configuration of Image Forming Apparatus FIG. 1 is a diagram illustrating the overall configuration of the image forming apparatus according to the first embodiment.
As shown in FIG. 1, the image forming apparatus according to the present embodiment is an electrophotographic full-color tandem color digital printer 1 (hereinafter simply referred to as “printer 1”), and is connected to a network such as a LAN. When an instruction to execute a print (print) job is received from an external terminal device (not shown) that is connected, yellow (Y), magenta (M), cyan (C), black (K) are received based on the instruction. ) A color image is formed using a color toner.

  The printer 1 includes four image forming units 10Y, 10M, 10C, and 10K that form toner images of Y, M, C, and K colors. The image forming units 10Y, 10M, 10C, and 10K are opposed to the transfer belt 2 so as to face the transfer belt 2 from the upstream side in the rotational direction (hereinafter, simply referred to as “upstream side”) to the downstream side in the rotational direction. Hereinafter, they are simply arranged in series at predetermined intervals in the order of 10K, 10C, 10M, and 10Y. Hereinafter, the letters “Y”, “M”, “C”, and “K” are added to the reference numerals of components related to the colors Y, M, C, and K only when necessary. Omit case.

FIG. 2 is a diagram illustrating a schematic configuration of the image forming unit 10.
As shown in FIG. 2, the image forming unit 10 includes a photosensitive drum 11 as an image carrier, and a charger 12, an image exposure device 13, a developing device 14, and a cleaner 15 disposed around the photosensitive drum 11. . Each image forming unit 10 is positioned with respect to the printer main body 3 by the shaft 16 of the photosensitive drum 11.

The transfer belt 2 is formed of a sheet material made of an insulating resin, and is arranged around a plurality of rollers including the driving roller 4. The transfer belt 2 is rotationally driven in the direction indicated by the arrow in FIG. 1 by rotating the driving roller 4 by a driving means (not shown).
The printer 1 has a control unit 100. The control unit 100 receives an image signal for a print job transmitted from an external terminal device, adds necessary processing to the signal to generate image data, and uses the image data for driving each image forming unit 10. Is converted into a driving signal.

When each image forming unit 10 receives a drive signal from the control unit 100, the charging device 12 charges the surface of the photosensitive drum 11, and the image exposure device 13 forms an electrostatic latent image on the surface, and the developing device 14. The electrostatic latent image is developed to form toner images of colors Y, M, C, and K.
Below the transfer belt 2, a cassette 21 containing a sheet (for example, recording paper) as a transfer target is disposed. The recording paper is taken out by the paper feed roller 22 and conveyed to the registration roller 24 by the conveyance roller 23. The registration roller 24 temporarily stops the recording paper being conveyed, corrects skewing, and the like, and then sends it to the transfer belt 2 at a predetermined timing.

  Inside the transfer belt 2, a transfer charger 25 is disposed at a position facing the photosensitive drum 11. The recording paper fed to the transfer belt 2 is electrostatically attracted to the transfer belt 2 by an adsorption charging means (not shown), and is conveyed by the transfer belt 2 to a transfer position where the photosensitive drum 11 and the transfer charger 25 face each other. The At each transfer position, the transfer belt 2 is charged from the inside by the transfer charger 25, and the toner images on the photosensitive drum 11 are sequentially transferred onto the conveyed recording paper.

  The recording paper onto which the four color toner images have been transferred is discharged by the separation charger 26, separated from the transfer belt 2, and conveyed to a pair of fixing rollers 27 and 28. One of the fixing rollers 27 and 28 is heated by a heater (not shown), and the toner on the recording paper is thermally melted by the heat. As a result, the four-color toner images are fixed on the recording paper, and a full-color fixed image is formed. Finally, the recording paper on which the full-color image is formed is discharged onto a paper discharge tray 29 provided outside the printer main body 3.

  As described above, since the image forming unit 10 is arranged in the order of 10K, 10C, 10M, and 10Y along the transfer belt 2 from the upstream side to the downstream side, the toner images of the respective colors are superimposed on the recording paper. Then, the K color is the lowest layer, and the C, M, and Y color toner images are positioned thereon. By positioning the K color in the lowermost layer in this way, the C, M, and Y color toners positioned thereon are more easily melted by heat, and the color development is improved and the color reproducibility is improved.

As will be described later, the user can select a desired image forming mode from the operation panel 5. Here, the image forming mode includes a full color mode, a pseudo full color mode, and a monochrome mode.
The full color mode is an image forming mode in which color reproducibility is emphasized, and color image formation with four colors Y, M, C, and K or color image formation with three colors Y, M, and C is executed. This is an image forming mode. In the case of three colors of Y, M, and C, K color is reproduced by mixing Y, M, and C colors.

  The pseudo full-color mode is an image formation mode in which cost and speed are more important than color reproducibility in color image formation, and color image formation with three colors M, C, and K excluding Y color, or M, This is an image forming mode in which color image formation with two colors C is executed. Although the color reproducibility is reduced by the number of colors smaller than that of four colors, the amount of toner used for one recording sheet can be reduced. The pseudo full color mode is used, for example, when it is sufficient to represent a graph or the like in a company office or the like even if it cannot be reproduced in full color.

  The reason why the Y color is not used in the pseudo full color mode is that the Y color has less influence on the reproduced image than the other colors, and a decrease in color reproducibility can be minimized. On the other hand, the reason for leaving the K color is that black characters such as business documents can be reproduced more clearly than the black color due to the mixed color of Y, M, and C. In the case of two colors of M and C, it cannot be denied that the color reproducibility is lower than the three colors of M, C and K, but it is more advantageous in terms of cost.

The monochrome mode is an image formation mode for executing monochrome image formation with K color.
In the present embodiment, three types of image forming modes, the full color mode, the pseudo full color mode, and the monochrome mode, are set. However, the present invention is not limited to these and other image forming modes may be provided.

(2) Attachment / detachment of image forming unit The printer main body 3 is provided with four slots 6 as storage portions, and the image forming units 10 are detachably attached to the slots 6. When the user runs out of toner in a certain image forming unit 10, for example, the user can take out any installed image forming unit 10 and install a new image forming unit 10 to easily replace the unit. Can do.

To attach or detach the image forming unit 10, the user opens an exterior cover (not shown) and pulls out the image forming unit 10 stored in the slot 6 toward the front of the apparatus or pushes the image forming unit 10 toward the back of the apparatus. To do. Of course, this configuration is not limited as long as it is detachable.
Each image forming unit 10 has an output terminal 17. From the output terminal 17, an identification signal indicating which color corresponds is, for example, a 3-bit signal. For example, the image forming unit 10Y is “001”, 10M is “010”, 10C is “011”, 10K. Is output as “100”.

On the other hand, each slot 6 is provided with a unit connection terminal 7. One unit connection terminal 7 corresponds to one slot 6, and each unit connection terminal 7 is electrically connected to an output terminal 17 of the image forming unit 10 when the image forming unit 10 is installed in the slot 6. An identification signal connected and output from the output terminal 17 is transmitted to the control unit 100.
When receiving the identification signal of each imaging unit 10 via the unit connection terminal 7 (see FIG. 7), the controller 100 (see FIG. 7) determines which imaging unit in which slot 6 from the 3-bit information indicated by the identification signal. It is determined whether 10 is attached. Specifically, for example, when the identification signal of a certain slot 6 is “001”, it is determined that the image forming unit 10Y is attached to the slot 6.

Since each image forming unit 10 has basically the same shape, the user can mount an arbitrary image forming unit 10 in an arbitrary slot 6.
FIG. 3 is a diagram showing an example in which an image forming unit 10K is mounted in the slot 6 instead of the image forming unit 10Y.
In the case of the figure, since the image forming units 10M, 10C, and 10K are mounted, image formation in the pseudo full color mode and the monochrome mode is possible. Note that, in such a state where two image forming units 10K are mounted, operation control using either one or both of them is executed when the K color image is formed. This operation control will be described later.

Note that even when image formation is performed in the pseudo full color mode using the image forming units 10M, 10C, and 10K, the timing of a series of operations such as image forming operation, paper feeding, conveyance, transfer, fixing, and paper discharge by the image forming unit 10 Is the same as the timing of image formation with four colors.
FIG. 4 is a diagram illustrating an example in which the image forming unit 10 is not mounted in some of the slots 6.
In the case of the figure, since the image forming units 10M, 10C, and 10K are mounted, image formation in the pseudo full color mode and the monochrome mode is possible as in the example of FIG.

Each image forming unit 10 is provided with a toner remaining amount detection sensor 8 (see FIG. 7) for detecting the remaining amount of toner contained therein. As the toner remaining amount detection sensor 8, a known liquid level sensor, photoelectric sensor, or the like can be used. Here, the specific description is omitted.
A detection signal of the toner remaining amount detection sensor 8 is sent to the control unit 100. The control unit 100 can detect whether or not toner remains in the image forming unit 10 based on a detection signal from the toner remaining amount detection sensor 8.

  As described above, in the present embodiment, it is possible to form an image in the pseudo full color mode using M, C, and K color toners. However, since conventional M and C color toners are manufactured on the assumption that a color image is formed with four colors, that is, on the assumption that Y color toners are used, only M and C color toners are produced. In this case, a color image including the Y color component cannot be reproduced with high image quality.

Therefore, in the present embodiment, an image forming unit that can be mounted on the printer main body 3 instead of the image forming units 10M and 10C so that a color image including a Y color component can be reproduced using only M and C color toners. Units 10M ′ and 10C ′ (not shown) are prepared, for example, as options.
In the image forming unit 10M ′, the chromaticity point on the chromaticity diagram has a yellow hue as compared with the full-color magenta toner used when forming a color image with four colors of magenta, cyan, yellow, and black. The pseudo full color magenta toner shifted in the approaching direction is contained.

In the image forming unit 10C ′, the chromaticity point on the chromaticity diagram has a yellow hue compared to the full-color cyan toner used when forming a color image with four colors of magenta, cyan, yellow, and black. The pseudo full color cyan toner shifted in the approaching direction is accommodated.
(3) Regarding Chromaticity Point of Toner FIG. 5 is a chromaticity diagram showing chromaticity points of M and C toners in the L ^* a ^* b ^* color system. Here, for the M and C colors, the white circles indicate the chromaticity points of the toner used when the plot of the white circles is four colors (colors based on Y, M, C, and K colors), and the white squares indicate three colors The chromaticity point of the toner used in the case of color (color by M, C, K color) is shown.

As shown in the figure, for example, regarding magenta toner, a three-color toner has a chromaticity point at a position shifted in the red (R) direction from a four-color toner, and a C-color toner. As can be seen, it has a chromaticity point at a position shifted in the green (G) direction.
Here, the red direction means the hue direction of the R (red) color resulting from the mixture of the M color and the Y color. Having a chromaticity point at a position shifted in the red direction means that the hue of the M color is the color of the R color. It means getting close to hue.

Similarly, the green direction means the hue direction of G (green) color by the mixed color of C color and Y color, and having a chromaticity point at a position shifted in the green direction means that the hue of C color is changed to that of G color. It means getting close to hue.
Thus, as the M and C color toners, toners whose chromaticity points are shifted in the R and G color directions from those of the four color colors are used, so that the R color (which is realized by subtractive color mixing with the Y color ( R = M + Y) and G color (G = C + Y) color reproducibility can be secured to some extent even without Y color toner, and reproducibility of frequently used colors such as R color and G color can be improved.

The shift amount and the shift direction of the chromaticity points of the M and C toners can be obtained in advance by experiments or the like, and are not limited to the above. Using M and C color toners with chromaticity points shifted in a direction having a directional component approaching the hue of Y color on the chromaticity diagram with respect to the chromaticity points of M and C color toners used for four colors. This is because the color reproducibility can be improved.
For example, when Japan Color is used as a reference, the chromaticity point of M toner is set to R color (a ^* : 68.5, b ^* : 48.0) under the observation condition of the 2-degree visual field D50. The chromaticity point of the C-color toner may be arranged around or very close to the G color (a ^* : −73.5, b ^* : 25.0).

Further, even when another color standard such as SWOP (Specifications for Web Offset Publications) or Euro Color is used, the chromaticity point of the M and C color toners is brought close to the hue of R, G color or Y color. By doing so, the same effect can be obtained.
In the pseudo full color mode according to the present embodiment, both the image forming unit 10M ′ and the image forming unit 10C ′ are used. However, depending on the adjustment of the chromaticity point of the toner, the image forming unit 10M ′ or It is also conceivable to form a color image with high reproducibility in the pseudo full color mode using only one of the image forming units 10C ′. For example, a color image is formed in the pseudo full color mode using the image forming unit 10M ′ and the image forming unit 10C, or a color image is formed in the pseudo full color mode using the image forming unit 10M and the image forming unit 10C ′. Can be considered.

Further, as a method for producing a pseudo full-color toner, it is conceivable to employ a method in which a coloring material having a shifted chromaticity point is incorporated into a binder resin or the like in accordance with a conventional full-color toner production method. .
(4) Combination of image forming units 10 As described above, there are 10Y, 10M, 10M ′, 10C, 10C ′, and 10K as the image forming units 10, and the user can set any image forming unit 10 in any slot. 6 can be mounted. However, depending on the combination of the image forming units 10 to be mounted, there are cases where the full color mode, the pseudo full color mode, and the monochrome mode can all be executed, or none of the image forming modes can be executed.

Therefore, in this embodiment, it is determined in advance which image forming mode can be executed when the image forming unit 10 for which color is mounted, and when the image forming unit 10 is actually mounted. The image forming mode that can be executed from the combination is informed to the user, and the selection input from the user is received, and the selected image forming mode is executed.
FIG. 6 is a table showing the relationship between combinations of image forming units 10 and executable image forming modes.

  As shown in the figure, for example, a column 1001 is an example in the case where the image forming units 10Y, 10M, 10C, and 10K are mounted, and it can be understood that all image forming modes can be executed. Further, for example, a column 1002 is an example when the image forming units 10M, 10C, and 10K are mounted, and it can be understood that the pseudo full color mode and the monochrome mode can be executed. Further, for example, a column 1003 is an example in the case where the image forming units 10M ′, 10C ′, and 10K are mounted, and it can be understood that the pseudo full color mode and the monochrome mode can be executed also in this case.

  Each image forming unit 10 has a label (not shown) indicating information (name, etc.) for the user to identify which color the unit corresponds to, and which chromaticity point is filled with toner. Is attached, so that the user can distinguish each unit without observing the label. In addition, the column “for waste toner” in FIG.

(5) Configuration of Control Unit 100 FIG. 7 is a block diagram showing the configuration of the control unit 100.
As shown in the figure, the control unit 100 includes, as main components, a CPU 101, a communication interface (I / F) unit 102, an image processing unit 103, an image memory 104, an LD driving unit 105, and a RAM 106. A ROM 107 and a unit detection unit 108, and data can be exchanged via the bus 110.

The communication I / F unit 102 is an interface for connecting to a network such as a LAN such as a LAN card or a LAN board.
The unit detection unit 108 receives the identification signal of each mounted image forming unit 10 via the unit connection terminal 7 and detects which image forming unit 10 is mounted in which slot 6.

The image processing unit 103 performs known correction processing such as shading on the image signal received via the communication I / F unit 102, for example, red (R), green (G), and blue (B) data. Each pixel is converted into a digital image signal (image data) for Y, M, C, and K reproduction colors, and is output to the image memory 104.
FIG. 8 is a block diagram illustrating a configuration of the image processing unit 103.

As shown in the figure, the image processing unit 103 includes a luminance density conversion unit 121, a color correction unit 122, and an output unit 123.
The luminance density conversion unit 121 includes a switching unit 131 and conversion processing units 132 and 133, and converts luminance data into density data.
The switching unit 131 determines the brightness / density according to the mode information indicating which image forming mode is selected from the full color mode, pseudo full color mode, and monochrome mode by the user, and the unit detection result by the unit detection unit 108. It is selected whether the conversion processing unit 132 or the conversion processing unit 133 performs the conversion.

Specifically, when the full color mode or the monochrome mode is selected, the conversion processing unit 133 is selected.
The conversion processing unit 133 performs conversion from R, G, B indicating luminance to Y, M, C indicating density using a predetermined conversion formula. This conversion formula is based on the formula used in the known luminance / density conversion, taking into account the chromaticity point of the toner used, etc. so that the color reproducibility is optimized in the full color mode. It is generated by obtaining from experiment etc.

  Here, two formulas are prepared for the case of four colors Y, M, C, and K and the case of three colors Y, M, and C. This is because the combination of toner colors used to reproduce the color differs depending on the mounting state of the image forming unit 10. Which of the two expressions is selected is determined by the unit detection result. For example, in the case where the image forming units 10Y, 10M, 10C, and 10K are attached, the formula for the case of four colors Y, M, C, and K is selected.

On the other hand, when the pseudo full color mode is selected, the conversion processing unit 132 is selected.
The conversion processing unit 132 performs conversion from R, G, B to M, C using a predetermined conversion formula different from that of the conversion processing unit 133. Another conversion formula is generated by obtaining the coefficient of the formula in the conversion processing unit 133 from an experiment or the like so that the color reproducibility is optimized in the pseudo full color mode.

In the conversion processing unit 132, as an expression corresponding to the pseudo full color mode, when the imaging unit 10 is for M, C, and K colors, when the imaging unit 10 is for M and C colors, the imaging unit 10 is M ′. For C, C ′ and K colors, four formulas are prepared for the case where the image forming unit 10 is for M ′ and C ′ colors. Which formula is selected is the same as in the case of the conversion processing unit 133.
The switching unit 131 sends R, G, and B color data to the selected conversion processing unit. Upon receiving the R, G, and B color data, the conversion processing unit performs conversion into density data using its own conversion formula, and outputs the converted data to the color correction unit 122.

The color correction unit 122 includes correction processing units 141 and 142, and performs processing such as UCR (under color removal), BP (black generation), and γ correction on the data from the luminance density conversion unit 121, and includes K color. The image data is corrected and output to the output unit 123.
The correction processing unit 142 executes processing such as UCR using various conversion formulas for processing such as UCR determined in advance. This conversion formula is based on a well-known formula used in UCR or the like, and the coefficient is tested in consideration of the chromaticity point of the used toner so that the color reproducibility is optimal in the full color mode. It is produced | generated by calculating | requiring from.

As conversion formulas, formulas corresponding to combinations of colors to be used, here formulas corresponding to two formulas of the conversion processing unit 133 are prepared in advance, and formulas corresponding to formulas used in the conversion processing unit 133 are provided. Selected.
On the other hand, the correction processing unit 141 executes a process such as UCR using a conversion formula that is different from the correction processing unit 142 that is determined in advance. This other conversion formula is generated by obtaining the coefficient from experiments or the like so that the color reproducibility is optimized in the pseudo full color mode.

As another conversion formula, similar to the correction processing unit 142, formulas corresponding to the combination of colors to be used, here formulas corresponding to the four formulas of the conversion processing unit 132, are prepared in advance. The formula corresponding to the formula used in is selected.
In this sense, the conversion processing unit 132 and the correction processing unit 141 function as means for generating data of other reproduction colors excluding the Y color even when data including a Y color component as a reproduction color is input. It can be said that it has.

The output unit 123 stores the image data from the correction processing units 141 and 142 in the image memory 104 for each color.
Although the conversion processing unit 132 prepares four conversion formulas, for example, a method of using two conversion formulas or sharing one formula is used according to the degree of influence on color reproducibility. It is also good. Thereby, simplification of processes, such as conversion, can be achieved. The same applies to the conversion processing unit 133 and the correction processing units 141 and 142.

  In addition, although the method of changing the coefficient according to the image forming mode etc. is used based on the conventional conversion formula, it is not limited to this method. For example, the full color mode and the monochrome mode are basically the same as the conventional method. Conversion, correction, and the like are performed, and in the pseudo full color mode, a new conversion formula corresponding to a configuration for forming a color image using only the M, C, and K colors of the present invention may be obtained from experiments or the like. In addition, as long as data can be converted based on a predetermined condition, various methods such as a conversion table can be used without being limited to equations.

Returning to FIG. 7, under the control of the CPU 101, the LD driving unit 105 reads out image data for each color from the image memory 104, and drives the exposure units 13Y, 13M, 13C, and 13K.
The ROM 107 stores a program related to an image forming operation, a sheet feeding operation, and the like, a program related to a mode display process (described later) for notifying the user of selectable image forming modes and receiving the selection input.

The RAM 106 serves as a work area when the CPU 101 executes a program.
The CPU 101 reads a necessary program from the ROM 107 and controls the image forming operation, the sheet feeding operation, etc. in a unified manner while taking a timing to execute a smooth printing operation.
In addition, the CPU 101 executes processing for adjusting the timing from exposure to transfer for each color according to the combination of the mounted image forming units 10. That is, for example, when the image forming unit 10 is mounted in the order of K, C, M, and Y from the upstream side of the transfer belt 2, the image forming unit 10C is positioned on the downstream side with respect to the image forming unit 10K. , Y, M, C, and K are mounted in this order, the image forming unit 10C is positioned upstream of the image forming unit 10K, and which image forming unit 10 is mounted in which slot 6 This is because it is necessary to adjust the timing of exposure or the like depending on whether the exposure is performed.

  In the present embodiment, for each combination of image forming units 10 shown in the table of FIG. 6, it is determined at which timing exposure is optimal when each image forming unit 10 is mounted in which slot 6. The timing information obtained from an experiment or the like in advance is stored in the ROM 107. When the CPU 101 determines which image forming unit 10 is installed in which slot 6, the CPU 101 determines the exposure timing corresponding to the combination of the image forming units 10 installed from the timing information stored in the ROM 107. Read and acquire, and perform exposure and the like based on the acquired timing information. Further, mode display processing and the like are executed.

(6) Processing by Control Unit 100 FIG. 9 is a flowchart showing the contents of a print job executed by the control unit 100.
As shown in the figure, when receiving a print job, the control unit 100 executes a mode display process (step S1).

FIG. 10 is a flowchart showing the contents of the mode display process.
As shown in the figure, in the mode display process, first, the mounting state of the image forming unit 10 is detected (step S21). The detection is performed by the unit detection unit 108.
After detecting the mounting state, it is determined whether or not the Y, M, and C color image forming units 10 are mounted in the slot 6 (step S22). If it is determined that all the image forming units 10 are installed in the slot 6 (“YES” in step S22), it is further determined whether or not the K color image forming unit 10 is installed in the slot 6. (Step S23). If it is determined that the image forming unit 10 for K color is attached (“YES” in step S23), a message indicating that three image forming modes of the full color mode, the pseudo full color mode, and the monochrome mode can be selected. The information is displayed on the operation panel 5 (step S24), and the user is prompted to determine the image forming mode.

FIG. 11 is a diagram showing a message screen 111 of the operation panel 5 on which selectable image forming modes are displayed.
As shown in the figure, the message screen 111 of the operation panel 5 displays three buttons indicating a full color mode, a pseudo full color mode, and a monochrome mode. The user can select an image forming mode by touching a button indicating the image forming mode desired by the user.

  Note that it is only necessary to prompt the user to select an image forming mode. Therefore, the output method is not limited to the message display. For example, a method for outputting the information by voice or an external terminal requesting a print job can be used. On the other hand, it may be possible to take a method such as giving an instruction to display that effect. It should be noted that the fact that the present invention is not limited to the display is the same for each process related to the display of the message screen described below.

On the other hand, returning to step S23, if it is determined that the image forming unit 10K for K color is not attached ("NO" in step S23), two image forming modes, the full color mode and the pseudo full color mode, can be selected. A message indicating that there is a message is displayed on the operation panel 5 (step S25).
Returning to step S22, if it is determined that one of the three colors Y, M, and C is not attached (“NO” in step S22), a combination for M and C colors, or It is determined whether or not the image forming unit 10 is mounted with a combination of M ′ and C ′ colors (step S26).

  When it is determined that the image forming unit 10 is mounted in any combination (“YES” in step S26), it is further determined whether or not the K color image forming unit 10 is also mounted (step S27). ). When it is determined that the image forming unit 10 for K color is attached (“YES” in step S27), a message indicating that the two image forming modes of the pseudo full color mode and the monochrome mode can be selected is displayed on the operation panel 5. (Step S28).

On the other hand, returning to step S27, if it is determined that the image forming unit 10 for K color is not attached ("NO" in step S27), a message indicating that the pseudo full color mode can be selected is displayed on the operation panel 5. Displayed (step S29).
Returning to step S26, it is determined that any combination is not mounted ("NO" in step S26), and it is determined whether the K color image forming unit 10 is mounted (step S30). When it is determined that the image forming unit 10 for K color is attached (“YES” in step S30), a message that the monochrome mode can be selected is displayed on the operation panel 5 (step S31).

  Returning to step S30, if it is determined that the image forming unit 10 for K color is not attached ("NO" in step S30), a message screen indicating that there is no selectable image forming mode is displayed on the operation panel 5. Display (step S32) and return to step S21. When the image forming unit 10 is mounted by the user and one of the image forming modes can be executed, the process returns to the main routine through one of steps S24, S25, S28, S29, and S31. In this sense, the control unit 100 functions as an output unit that outputs an image forming mode corresponding to the combination of the image forming units 10 when executing the processes of steps S24, S25, S28, S29, S31 and the like. I can say that.

When a state in which none of the image forming modes can be executed continues for a predetermined time, a message indicating that the job cannot be executed is displayed on the operation panel 5, and the execution of the job is suspended or deleted. You can also
In the above description, the user selects a desired image forming mode from the image forming modes displayed on the message screen 111. However, when the required image forming mode is not displayed on the message screen 111, the user The image forming unit 10 can be replaced.

For example, when only the monochrome mode is displayed on the message screen 111 and the user desires printing in the full color mode, a part or all of the image forming unit 10 installed in the slot 6 is replaced, and Y, M If the three-color image forming units 10 of C and C are installed in the slot 6, printing in the full color mode becomes possible.
In addition, when a part or all of the image forming unit 10 is exchanged by the user while the message screen 111 is displayed, it is possible to return to step S21 and execute the processing after step S22 again. . For example, this is convenient when printing in the full color mode is desired but the message screen 111 displays that only the monochrome mode can be executed, and the full color mode cannot be selected.

Further, although the user has selected the image forming mode, for example, the printer 1 may automatically perform the selection. For example, when a plurality of image forming modes can be executed, a method of giving priority to image quality and determining an image forming mode using a larger number of image forming units as an image forming mode to be executed may be considered.
Further, for example, when it is assumed that the user has mistakenly attached the image forming unit 10, a message screen indicating that is displayed on the operation panel 5 separately from the message screen 111 described above, and the image forming unit 10 is displayed to the user. May be urged to be exchanged, and thereafter, the processing after step S22 may be executed. As an example of incorrect mounting, a combination of the image forming units 10M ′ and 10C, and 10M and 10C ′, that is, a combination of a shifted chromaticity point and a non-shifted chromaticity point may be considered.

  Returning to FIG. 9, in step S2, if there is a touch input by the user from the message screen 111 displayed by the mode display processing in step S1, it is determined that the image forming mode selection input has been accepted, and the process proceeds to the next step S3, where the message is displayed. The screen 111 is turned off. In this sense, it can be said that the control unit 100 functions as a receiving unit that receives designation of an image forming mode desired by the user when executing the process of step S2.

In step S3, it is determined whether or not there are a plurality of the same color for the image forming unit 10 to be used when executing the selected image forming mode. This is because when there are a plurality of image forming units 10 for the same color, which image forming unit 10 is used for printing is determined before printing.
In the case where there are image forming units 10 for the same color, when the image forming units 10 are (a) all four are for the same color, (b) three are for the same color and the remaining one is for another color. If (c) two are for the same color and the remaining two are for different colors, (d) two patterns are for the same color and the remaining two are for different colors and the same color Conceivable.

Here, with respect to the image forming units 10 for the same color, the image forming units 10 to be used are determined so that the toner is basically consumed in order from the upstream one.
Specifically, if it is determined that there are a plurality of image forming units 10 for the same color (“YES” in step S3), it is determined whether there is only one set of image forming units 10 for the same color. (Step S4). If it is determined that only one set exists (“YES” in step S4), it is determined whether or not the number of image forming units 10 for the same color is four (step S5). If it is determined that the number is not four (“YES” in step S5), it is further determined whether or not the number of image forming units 10 for the same color is three (step S6). If it is determined that there are not three, that is, two ("NO" in step S6), unit determination processing 1 is executed (step S7).

FIG. 12 is a flowchart showing the contents of the unit determination process 1.
As shown in the figure, in the unit determination process 1, first, first and second numbers are assigned to the two image forming units 10 for the same color in order from the upstream side (step S41). Next, it is determined whether or not the first image forming unit 10 is empty (step S42). If it is not empty, that is, if toner is contained (“NO” in step S42), the image forming used for printing is performed. The unit 10 is determined to be the first image forming unit 10 (step S43).

  On the other hand, when the first image forming unit 10 is empty (“YES” in step S42), it is determined whether or not the second image forming unit 10 is empty (step S44). If 10 is not empty (“NO” in step S44), the image forming unit 10 used for printing is determined as the second image forming unit 10 (step S45). If it is determined that the second image forming unit 10 is also empty (“YES” in step S44), it is displayed on the operation panel 5 that the toner of that color is empty (step S46). It is urged to replace the image forming unit 10.

  Returning to FIG. 9, in step S8, a print process for forming an image in the image forming mode selected in step S2 is executed, and the print job is terminated. For example, the selected image forming mode is the pseudo full color mode, and the image forming units 10M ′, 10C ′, 10K (first), and 10K (second) are mounted, and the determined image forming unit 10 is 10K. In the case of (second), the image forming units 10M ′, 10C ′, 10K (second) are used for forming a pseudo full-color image.

Even when another job is subsequently executed, the above processing is executed each time. Therefore, when there are a plurality of image forming units 10 for the same color, the use order is determined so that the toner is consumed in order from the upstream image forming unit 10. This also applies to unit determination processes 2 to 4 described later.
In the above description, the condition for determining the image forming unit 10 to be used is determined based on whether the toner is empty or not. However, the present invention is not limited to this. For example, it can be determined by whether or not image formation is possible, such as the presence or absence of a mechanical or electrical failure of the image forming unit 10.

Returning to step S6, when there are three image forming units 10 for the same color ("YES" in step S6), unit determination processing 2 is executed (step S9).
FIG. 13 is a flowchart showing the contents of the unit determination process 2.
As shown in the figure, in the unit determination process 2, first, the first, the second, and the third are assigned to the three image forming units 10 of the same color in order from the upstream side (step S51). Next, it is determined whether or not the first image forming unit 10 is empty (step S52). If it is determined that the first image forming unit 10 is not empty, ie, contains toner ("NO" in step S52), it is used for printing. The image forming unit 10 is determined to be the first image forming unit 10 (step S53).

  Returning to step S52, if the first image forming unit 10 is empty ("YES" in step S52), it is determined whether or not the second image forming unit 10 is empty (step S54). If the image forming unit 10 is not empty (“NO” in step S54), the image forming unit 10 used for printing is determined as the second image forming unit 10 (step S55).

  If the second image forming unit 10 is also empty (“YES” in step S54), it is determined whether or not the third unit is empty (step S56), and the third unit is not empty (step S56). The image forming unit 10 used for printing is determined as the third image forming unit 10 (“NO” in S56) (step S57). If it is determined that the third image forming unit 10 is also empty (“YES” in step S56), it is displayed on the operation panel 5 that the toner of that color is empty (step S58), and the user is made Exchange of the image unit 10 is urged.

  As described above, even when there are three image forming units 10 for the same color, only one image forming unit 10 is used. Returning to FIG. 9, when the image forming unit 10 to be used for printing is determined (step S9), the image forming unit 10 determined in the unit determining process 2 (step S9) is used for the color in which a plurality of image forming units 10 exist. Then, for each of the other colors, only one image forming unit 10 of that color is used, and a printing process is performed (step S8).

Returning to step S5, when there are four image forming units 10 of the same color ("YES" in step S5), unit determination processing 3 is executed (step S11).
FIG. 14 is a flowchart showing the contents of the unit determination process 3.
As shown in the figure, in the unit determination process 3, first, the second, the third, the fourth, and the numbers are assigned to the four image forming units 10 for the same color in order from the upstream side (step S61). Next, it is determined whether or not the first image forming unit 10 is empty (step S62). If it is determined that the first image forming unit 10 is not empty, that is, contains toner ("NO" in step S62), it is used for printing. The image forming unit 10 to be determined is determined to be the first image forming unit 10 (step S63).

  On the other hand, when the first image forming unit 10 is empty (“YES” in step S62), it is determined whether or not the second image forming unit 10 is empty (step S64). If 10 is not empty (“NO” in step S64), the image forming unit 10 used for printing is determined as the second image forming unit 10 (step S65).

If the second image forming unit 10 is also empty (“YES” in step S64), it is determined whether or not the third image forming unit 10 is empty (step S66). If it is not empty (“NO” in step S66), the image forming unit 10 used for printing is determined to be the third image forming unit 10 (step S67).
If the third image forming unit 10 is also empty (“YES” in step S66), it is determined whether or not the fourth image forming unit 10 is empty (step S68). If it is not empty (“NO” in step S68), the image forming unit 10 used for printing is determined as the fourth image forming unit 10 (step S69). If it is determined that the fourth image forming unit 10 is also empty (“YES” in step S68), it is displayed that the toner of that color is empty (step S70), and the image forming unit 10 is displayed to the user. Encourage exchange.

As described above, even when there are four image forming units 10 for the same color, only one image forming unit 10 is used.
Returning to FIG. 9, when the image forming unit 10 to be used for printing is determined (step S10), the image forming unit 10 determined in the unit determining process 3 (step S10) is used for a color in which a plurality of image forming units 10 exist. Then, for each of the other colors, only one image forming unit 10 for that color is used, and a printing process is performed (step S8).

Returning to step S4, if there is not one set of image forming units for the same color ("NO" in step S4), that is, if two are for the same color and the other two are for the same color, unit determination processing 4 is executed.
FIG. 15 is a flowchart showing the contents of the unit determination process 4. As shown in the figure, in the unit determination process 4, first, the first and second numbers are assigned in order from the upstream side to the image forming units 10 of the first color and the second color (step S71). .

Next, it is determined whether or not the first image forming unit 10 of the first color is empty (step S72). If it is determined that the first color image forming unit 10 is not empty, that is, contains toner ("NO" in step S72). The image forming unit 10 used for printing is determined as the first image forming unit 10 (step S73).
Returning to step S72, if the first image forming unit 10 is empty ("YES" in step S72), it is determined whether or not the second image forming unit 10 is empty (step S74). If the image forming unit 10 is not empty ("NO" in step S74), the unit used for printing is determined as the second image forming unit 10 (step S75). If it is determined that the second image forming unit 10 is also empty (“YES” in step S74), it is displayed on the operation panel 5 that the toner of that color is empty (step S76), and the image forming unit is displayed. Prompt 10 replacements.

Next, it is determined whether or not the first image forming unit 10 of the second color is empty (step S77). If the second image forming unit 10 is not empty (“NO” in step S77), the image forming unit 10 used for printing is determined as the first image forming unit 10 (step S78).
Returning to step S77, if the first image forming unit 10 is empty (“YES” in step S77), it is determined whether or not the second image forming unit 10 is empty (step S79). When it is determined that the image forming unit 10 is not empty (“NO” in step S79), the image forming unit 10 used for printing is determined as the second image forming unit 10 (step S80). If it is determined that the second image forming unit 10 is also empty (“YES” in step S79), it is displayed that the toner of that color is empty (step S81), and the image forming unit 10 is replaced. Prompt.

As described above, when there are two sets of image forming units 10 for the same color, the number of image forming units 10 used for each color is reduced to one.
Returning to FIG. 9, when the image forming unit 10 to be used for printing is determined (step S11), the image forming unit 10 determined in the unit determining process 4 (step S11) is used for the color in which a plurality of image forming units 10 exist. Then, for each of the other colors, only one image forming unit 10 of that color is used, and a printing process is performed (step S8).

  Returning to step S3, if the image forming unit 10 for the same color does not exist (“NO” in step S3), it is determined whether or not the image forming unit 10 for color necessary for image formation is empty ( In step S12), if there is an empty image forming unit 10 ("YES" in step S12), the operation panel 5 is displayed as being empty (step S13). If it is determined that the empty image forming unit 10 does not exist as a result of the user changing the image forming unit 10 or the like ("NO" in step S12), print processing is performed (step S8).

In the above description, the user selects the image forming mode. However, for example, the configuration in which step S3 is executed first without executing the processing in steps S1 and S2, or S3 is executed after step S1 (S2). It is also possible to adopt a configuration.
In this case, for example, a configuration in which the printer 1 automatically selects an image forming mode can be employed. As a specific example, there is a method of determining an image forming mode using a larger number of image forming units 10 as an image forming mode to be executed in order to prioritize image quality when a plurality of image forming modes can be executed. It is done. Further, the image forming mode may be designated in advance by the user or the like, and the designated image forming mode may be executed as the image forming mode to be executed.

  Further, when there is only one executable image forming mode, the user cannot substantially select the image forming mode, so only the display for confirmation is performed and the designation from the user is not accepted. A configuration in which the one image forming mode is executed can also be adopted. Moreover, it is good also as a structure which does not perform output itself. As a result, processing can be simplified as much as processing such as selection is not performed, and the burden on the CPU 101 can be reduced.

  In the above description, when there are a plurality of image forming units 10 for the same color, the order of use is determined so that the toner is consumed in order from the upstream image forming unit 10. An optimal order can be determined in advance. For example, the order of the image forming units 10 to be used may be determined so that the toner is consumed in another order such as in order from the downstream image forming unit 10.

As a modified example, the unit determination process selectively executes the above-described process of using a plurality of image forming units 10 for the same color one by one and a process in which toner is evenly consumed. Other configurations are possible.
FIG. 16 is a flowchart showing the contents of unit determination processing 1 according to the modification.
As shown in the figure, first and second numbers are assigned to the two image forming units 10 for the same color in order from the upstream side (step S91). Next, it is determined whether or not the first image forming unit 10 is empty (step S92), and if it is determined that the first image forming unit 10 is not empty, that is, contains toner ("NO" in step S92), then the second one. It is determined whether or not the image forming unit 10 is empty (step S93), and if the second image forming unit 10 is not empty (“NO” in step S93), a selection input for use conditions is accepted (step S93). S94).

  Accepting the selection input of the use condition means accepting selection from the user of a toner consumption method such as a method of evenly consuming the toner or a method of consuming one unit at a time for the image forming unit 10 for the same color. To do. Here, as the consumption method, a button indicating a method such as equality or one unit is displayed on the operation panel 5, and a touch input by the user is accepted as a selection input for the consumption method. In this sense, it can be said that the control unit 100 functions as an accepting unit that accepts designation of a method of use when executing the processing of step S94 and the like.

  If the user selects to consume the toner evenly (“YES” in step S95), the image forming unit 10 used for printing is determined as both the first and second (step S96). On the other hand, if the user selects to consume toner one unit at a time (“NO” in step S95), the order of use of the image forming units 10 used for printing is determined from the upstream side (step S97).

Returning to step S92, the first image forming unit 10 is not empty ("NO" in step S92). If the second image forming unit 10 is empty ("YES" in step S93), it is used for printing. The image forming unit 10 is determined to be the first image forming unit 10 (step S98).
Returning to step S92, if the first image forming unit 10 is empty (“YES” in step S92), it is determined whether or not the second image forming unit 10 is empty (step S99). ). If the second image forming unit 10 is not empty (“NO” in step S99), the image forming unit 10 used for printing is determined as the second image forming unit 10 (step S100). On the other hand, when the second image forming unit 10 is empty (“YES” in step S99), the fact that the toner of that color is empty is displayed on the operation panel 5 (step S101), and the user of the image forming unit 10 is displayed. Encourage exchange.

  As described above, when there are two image forming units 10 for the same color and neither of the image forming units 10 is empty and a method of consuming toner equally is selected, these two image forming units 10 are used. The image forming unit 10 is determined. In this case, as described in the print processing portion according to the next modification, the toners of the two image forming units 10 are alternately switched so that they are consumed evenly. In FIG. 16, the case where there are two image forming units 10 for the same color has been described as a representative example. However, in the case where there are three or four image forming units 10 as well, all the non-empty units are present. The image forming unit 10 is determined as the image forming unit 10 to be used.

FIG. 17 is a flowchart showing the contents of print processing according to the modification.
As shown in the figure, it is first determined whether or not it has been decided to use both image forming units 10 in the unit decision processing 1 (step S111). When it is determined in the unit determination process 1 that only the first or second image forming unit 10 is used (“NO” in step S111), printing is performed by the determined image forming unit 10 (step S111). S112).

  Returning to step S111, if it is determined in the unit determination process 1 that both image forming units 10 are to be used ("YES" in step S111), a variable n representing a print page is set to 1 (step S113), 1 The remaining amount of toner in the second image forming unit 10 is set to Z1 (step S114), and the remaining amount of toner in the second image forming unit 10 is set to Z2 (step S115).

The determination of the remaining amount of toner is performed based on the detection signal from the toner remaining detection sensor 8, but is not limited thereto. For example, for each recording sheet, the amount of toner that will be consumed by image formation is estimated from the gradation value of each pixel, and a value obtained by subtracting the estimated toner consumption from a predetermined value is calculated. You may take the method of remaining amount.
Next, X = Z1-Z2 is calculated (step S116). Then, it is determined whether or not the relationship X> A is established (step S117). If not (“NO” in step S117), it is further determined whether or not the relationship X <A is satisfied (step S117). (Step S118) If this is not established ("NO" in Step S118), it is decided to use both the first and second image forming units 10 (Step S119). Area allocation processing for equalizing the toner consumption amount is permitted (step S120).

The area allocation process is a process for making the toner consumption amounts of the two image forming units 10 substantially equal, specifically, a process of using the two image forming units 10 by alternately switching them based on a predetermined condition. That is.
When the area allocation processing is permitted (step S120), the image forming area of each image forming unit 10 is allocated from the dot counter, and the nth page (here, 1) is used by using the toner of the two image forming units 10 equally. Page) is printed (step S121).

FIG. 18 is a schematic diagram showing the state of the image forming area assigned to each image forming unit 10 for one recording sheet. Here, the direction indicated by arrow CD corresponds to the main scanning direction, the direction indicated by arrow FD corresponds to the sub-scanning direction, and also corresponds to the conveyance direction of the recording paper.
In the example shown in the figure, the image forming areas assigned to the first and second image forming units 10 are approximately half of one sheet of recording paper. The area from the front end to the center of the recording paper in the sub-scanning direction corresponds to the area formed by the first image forming unit 10, and the area from the center of the recording paper to the rear end is formed by the second image forming unit 10. This corresponds to the area.

  As such an allocation method, for example, for one recording sheet, the total number of pixels of an image to be formed as a toner image of the corresponding color is set to the first line, the second line, etc. for each main scanning line. In this order, the main scanning line in which the count number is divided into two is obtained, and the first image forming unit 10 is used to form the first area corresponding to the leading end of the recording paper from the line. There is a method of performing image formation by switching to the second image forming unit 10 for the second area corresponding to the recording paper rear end side of the line. As this switching method, for example, for each image forming unit 10, there is a method of switching between supply and stop of voltage for image formation in accordance with the timing when the first and second regions pass the development position.

  As a method of counting the number of pixels of the formed image, for example, the tone value of all pixels is read out from the image data stored in the image memory 104 and corresponds to the background of the document image. A method of counting the number of pixels other than the pixels, and a method of counting the number of pixels other than the pixels corresponding to the background by referring to the luminance of all the pixels of the driving signal output from the LD driving unit 105 with respect to the color signal Etc. can be taken.

  On the other hand, returning to step S117, if the relationship X> A is established ("YES" in step S117), it is determined that the first image forming unit 10 forms the nth page (step S124). Area allocation processing is prohibited (step S126). Returning to step S118, if the relationship X <A is satisfied (“YES” in step S118), it is determined that the second image forming unit 10 forms the nth page (step S125). Area allocation processing is prohibited (step S126).

When the area allocation processing is prohibited (step S126), the n-th page (here, the first page) is printed using the determined image forming unit 10 (step S121).
After the image formation, it is determined whether or not the n (= 1) page is the last page (step S122). If it is the last page (“YES” in step S122), the printing process is terminated. On the other hand, if the first page is not the last page (“NO” in step S122), n = n + 1 is set (step S123), and the process returns to step S114. In this sense, it can be said that the control unit 100 functions as switching means for switching the image forming unit when executing the processes of steps S113 to S126 and the like.

As described above, when two or more image forming units 10 for the same color are mounted, the remaining amount of toner in the image forming unit 10 for the same color is not always the same. 10 is used preferentially and the toner is consumed evenly.
Note that the method of consuming the toner uniformly is not limited to the above. For example, the above processing may be executed each time image formation is performed on a plurality of sheets, one page, or a plurality of pages, or each time one or more jobs are completed.

  Further, regardless of the remaining amount of toner in each image forming unit 10, every time image formation is performed on one sheet, a plurality of sheets, one page, or a plurality of pages, each time one or more jobs are completed, etc. A method of alternately switching units to be used may be used. Specifically, for example, the first image forming unit 10 is used for the first recording paper and the second image forming unit 10 is used for the second recording paper. It is possible to consume toner.

<Second Embodiment>
The image forming apparatus according to the first embodiment is configured to multiplex-transfer images of each color onto a recording sheet as a transfer target conveyed by a transfer belt, but the image forming apparatus according to the second embodiment This is a so-called intermediate transfer system configuration in which toner images of respective colors are multiplex-transferred onto an intermediate transfer belt as a transfer target, and the images after multiple transfer are collectively transferred onto a sheet (for example, recording paper).

Further, the image forming apparatus according to the second embodiment has a configuration in which a waste toner collecting unit for collecting residual toner on the intermediate transfer belt can be attached to and detached from the slot instead of the image forming unit.
Hereinafter, for convenience of explanation, description of components common to those of the image forming apparatus according to the first embodiment will be omitted or simplified, and image formation according to the second embodiment will be centered on the above differences. The apparatus will be described.

(1) Printer Configuration FIG. 19 is a diagram illustrating an overall configuration of an image forming apparatus according to the second embodiment.
As shown in the figure, a printer 200 as an image forming apparatus according to the second embodiment includes image forming units 210M ′, 210C ′, and 210K corresponding to the respective colors M, C, and K, and in the arrow direction. An intermediate transfer unit 220 including a rotating intermediate transfer belt 225, a feeding unit 230, a fixing unit 240, and a control unit 300 are provided. When the printer 200 is connected to a network such as a LAN and receives an instruction to execute a print job from an external terminal device (not shown), the printer 200 executes image formation based on the instruction.

  The image forming units 210M ′, 210C ′, and 210K are opposed to the intermediate transfer belt 225 so that the image forming units 210M ′, 210C ′, and 210K are upstream along the intermediate transfer belt 225 in the rotation direction (hereinafter simply referred to as “upstream side”). (Hereinafter, simply referred to as “downstream side”) 210M ′, 210C ′, and 210K are arranged in series at predetermined intervals. Hereinafter, the letters “Y”, “M”, “C”, and “K” are added to the reference numerals of components related to the colors Y, M, C, and K only when necessary, and otherwise. Is omitted.

Each image forming unit 210 includes a photosensitive drum 211 as an image carrier, and a charger 212, an image exposure device 213, a developing device 214, and a cleaner 215 arranged around the photosensitive drum 211. Each image forming unit 210 is positioned with respect to the printer main body 203 by the shaft 216 of the photosensitive drum 211.
The intermediate transfer unit 220 includes a driving roller 221, a driven roller 222, a tension roller 223, a primary transfer roller 224 that faces the photosensitive drum 211, and an intermediate transfer member that is stretched between the rollers 221, 222, and 223. Intermediate transfer belt 225 and the like.

The feeding unit 230 includes a paper feed cassette 231 that stores recording paper, a feed roller 232 that feeds the recording paper in the paper feed cassette 231 one by one, a pair of transport rollers 233 that transport the fed recording paper, A pair of timing rollers 234 for taking the timing of feeding the recording paper to the secondary transfer position, a secondary transfer roller 235, and the like are provided.
Upon receiving a print instruction from an external terminal device, the control unit 300 receives the transmitted image signal, converts it into a digital image signal for M, C, and K colors, and drives the exposure unit 213. A drive signal for generating is generated. The exposure unit 213 receives a drive signal from the control unit 300, emits laser light for image formation, and performs exposure scanning on the photosensitive drum 211 in the main scanning direction.

The photosensitive drum 211 is uniformly charged by a charger 212 after the toner remaining on the surface is removed by a cleaner 215 before being subjected to the exposure, and is erased by irradiating an eraser lamp (not shown). When exposed to the laser beam in a uniformly charged state, an electrostatic latent image is formed on the surface of the photosensitive drum 211.
Each electrostatic latent image is developed by a developing device 214 of each color, whereby a toner image as a developer image of M, C, and K colors is formed on the surface of the photosensitive drum 211, and is intermediate at each primary transfer position. The image is primarily transferred onto the rotating intermediate transfer belt 225 by an electrostatic force generated by a voltage applied to a primary transfer roller 224 disposed on the back side of the transfer belt 225.

  At this time, the image forming operation for each color is executed with the timing shifted from the upstream side to the downstream side so that the toner image is primarily transferred to be superimposed on the same position on the intermediate transfer belt 225. As a result, the toner images are superimposed in the order of M, C, and K from the bottom. The superimposed color toner images on the intermediate transfer belt 225 are moved to the secondary transfer position by the rotation of the intermediate transfer belt 225. In this sense, the image forming units 210M ′, 210C ′, and 210K and the intermediate transfer unit 220 function as image forming means. On the other hand, in accordance with the movement timing of the intermediate transfer belt 225, a recording sheet is fed from the feeding unit 230 via the timing roller 234. The recording sheet is separated from the rotating intermediate transfer belt 225. The toner image on the intermediate transfer belt 225 is transferred onto the recording paper by the electrostatic force generated by the voltage applied to the secondary transfer roller 235 at the secondary transfer position while being sandwiched between the secondary transfer rollers 235. Transcribed. Since the toner images are in the order of M, C, and K from the bottom on the intermediate transfer belt 225, they are in the order of K, C, and M from the bottom on the recording paper, and the K-color toner image is positioned at the lowest layer. become. In this way, the color reproducibility can be further improved by placing the K-color toner image on the recording paper in the state of being positioned at the lowermost layer.

The recording paper that has passed through the secondary transfer position is conveyed to the fixing unit 240, where the toner image is heated and pressed to be fixed on the recording paper, and then onto the discharge tray 242 via a pair of discharge rollers 241. Discharged.
The printer 1 includes a cleaner 250. The cleaner 250 includes a blade 251 for scraping off the residual toner on the intermediate transfer belt 225 after the transfer, and a storage unit 252 for storing the scraped waste toner.

  The shaft 253 of the blade 251 is connected to the rotating shaft of the switching motor 254 via a power transmission mechanism including a gear (not shown). The switching motor 254 is connected to the control unit 300, and the control unit 300 rotates the switching motor 254 to move the blade 251 in the direction of the arrow shown in FIG. 19 and to contact the intermediate transfer belt 225. The position is switched to a position away from the intermediate transfer belt 225.

The cleaner 250 is provided with a collected toner detection sensor 255 (see FIG. 21) for detecting the amount of collected toner, and a signal corresponding to the amount of toner collected in the storage unit 252. Is output.
As the collected toner detection sensor 255, for example, a known liquid level sensor can be used. Further, the storage unit 252 is supported by an elastic body such as a coil spring (not shown) from the lower side, and the height position of the storage unit 252 lowered by the weight of the accumulated waste toner is used as an optical sensor as the collected toner detection sensor 255. It may be configured to detect with.

A waste toner collection unit 260 is installed in one of the slots 206. The waste toner collecting unit 260 has substantially the same external shape and size as the image forming unit 210 and can be installed in any slot 206.
FIG. 20 is a diagram showing a schematic configuration of the waste toner recovery unit 260. As shown in the figure, the waste toner collection unit 260 includes a blade 261 that scrapes off the waste toner on the intermediate transfer belt 225 and a storage unit 262 that stores the waste toner scraped off by the blade 261. The accommodating portion 262 can be exchanged by the user.

  The shaft (not shown) of the blade 261 is connected to the rotating shaft of the switching motor 263 via a power transmission mechanism including a gear (not shown). The switching motor 263 is connected to the control unit 300, and the control unit 300 can move the blade 261 to the positions of the solid line and the broken line in FIG. 20 by driving the switching motor 263 to rotate. Here, the position of the broken line of the blade 261 is a position where the tip of the blade 261 contacts the intermediate transfer belt 225, and the position of the solid line indicates a position where the tip of the blade 261 is separated from the intermediate transfer belt 225.

The residual toner on the intermediate transfer belt 225 is scraped off by the blade 261 when the blade 261 is at the position of the broken line, and the scraped toner is stored in the storage unit 262.
The waste toner collection unit 260 is provided with a collected toner detection sensor 264 (see FIG. 21) for detecting the amount of collected toner. The collected toner detection sensor 264 basically has the same function as the collected toner detection sensor 255 of the cleaner 250, and a signal corresponding to the amount of toner collected in the storage unit 252 is output. Yes.

A detection signal from the collected toner detection sensor 264 is sent to the control unit 300. Based on the detection signal from the collected toner detection sensor 264, the control unit 300 can determine how much toner is collected in the waste toner collection unit 260 and whether the toner can be collected.
A known liquid level sensor, photoelectric sensor, bulk sensor, or the like can be used as the collected toner detection sensor 264, and a signal corresponding to the amount of toner stored in the storage unit 252 is output. ing.

  The waste toner collecting unit 260 has an output terminal 265 that outputs an identification signal indicating that it is a unit that collects waste toner, for example, “111” as a 3-bit signal. The output terminal 265 is electrically connected to the unit connection terminal 207 of the slot 206 in which the waste toner collection unit 260 is installed. As a result, the identification signal output from the output terminal 265 is sent to the control unit 300 as in the case where the image forming unit 210 is mounted in the slot 206.

FIG. 21 is a block diagram illustrating a configuration of the control unit 300 according to the second embodiment.
As shown in the figure, the control unit 300 includes, as main components, a CPU 301, a communication interface (I / F) unit 302, an image processing unit 303, an image memory 304, an LD driving unit 305, and a RAM 306. A ROM 307 and a unit detection unit 308, and data can be exchanged via the bus 310.

  Each component of the control unit 300 basically has the same function as the component of the same name of the control unit 100 according to the first embodiment. Further, the unit detection unit 308 (see FIG. 21) of the control unit 300 receives the identification signal from the waste toner collection unit 260 as well as the image forming unit 210, and reads the 3-bit information indicated in the signal. Thus, it is possible to detect in which slot 206 the waste toner collecting unit 260 is installed.

  The image forming unit 210 that can be used in combination with the waste toner collecting unit 260 is shown as a combination shown in each column in the “waste toner” column of FIG. It is decided in advance. For example, in the field 1004, the image forming units 210M ′, 210C ′, 210K, and the waste toner collecting unit 260 are combined (example in FIG. 19).

(2) Cleaning Process by Control Unit 300 FIG. 22 is a flowchart showing the content of the cleaning process by the control unit 300. This process is executed every time printing is performed on one sheet of recording paper.
As shown in the figure, it is determined whether or not the cleaner 250 is in a state where the residual toner cannot be collected (hereinafter referred to as “saturated state”) (step S131). This determination is made based on a detection signal from the collected toner detection sensor 255.

If not saturated (“NO” in step S131), cleaning is performed using the cleaner 250 (step S132).
On the other hand, if the cleaner 250 is saturated (“YES” in step S131), it is determined whether the waste toner recovery unit 260 is attached (step S133). If the cleaner 250 is attached (“ YES ”), it is determined whether the waste toner recovery unit 260 is saturated (step S134). If it is determined that it is not saturated (“NO” in step S134), cleaning is performed using the waste toner recovery unit 260 (step S135).

Returning to step S133, if the waste toner collection unit 260 is not attached ("NO" in step S133), a message prompting the replacement of the cleaner 250 or the attachment of the waste toner collection unit 260 is displayed on the operation panel 205 ( Step S136), the process returns to step S131.
Returning to step S134, if the waste toner collection unit 260 is saturated (“YES” in step S134), a message prompting the replacement of the cleaner 250 or the replacement of the waste toner collection unit 260 is displayed on the operation panel 205. (Step S137), the process returns to Step S131. In this sense, it can be said that the control unit 300 functions as a switching unit that switches between the cleaner 250 and the waste toner collecting unit 260 when executing the cleaning process.

In the above description, the cleaning is mainly performed by the cleaner 250, and the waste toner recovery unit 260 is used as a spare when the cleaner 250 is saturated. However, the cleaning is mainly performed by the waste toner recovery unit 260. It is possible to use a cleaner 250 as a spare.
(3) Another Cleaning Process by Control Unit 300 In the above cleaning process, when the cleaner 250 is saturated, the waste toner collection unit 260 is used next, but the order of use is not limited to this. For example, the cleaner 250 and the waste toner recovery unit 260 may be configured to use both alternately so that the toner recovery amounts are the same.

FIG. 23 is a flowchart showing the contents of another cleaning process performed by the control unit 300. This process is executed every time printing is performed on one sheet of recording paper.
As shown in the figure, it is determined whether or not the cleaner 250 is saturated (step S141). If the cleaner 250 is not saturated (“NO” in step S141), whether the waste toner collection unit 260 is further attached. (Step S142), and if it is attached (“YES” in step S142), it is determined whether the waste toner collection unit 260 is saturated (step S143). If it is determined that it is not saturated (“NO” in step S143), it is determined which of the cleaner 250 and the waste toner collection unit 260 is used, and cleaning is performed using the determined one (step S144).

  When cleaning is performed using both the cleaner 250 and the waste toner collecting unit 260 (step S144), first, the saturation level of the waste toner storage unit 252 of the cleaner 250 is set to A (0 to 100), and the waste toner collecting unit 260 is used. Let the saturation level of the storage portion 262 be B (0 to 100). In each case, 0 is empty and 100 is saturated. The saturation level of the storage unit 262 is detected by using a liquid level sensor, or a coil spring (not shown) is provided below the storage unit 262 so that waste toner accumulates in the storage unit 262 and the storage unit is lowered. It is conceivable to detect this with an optical sensor.

If A ≦ B, the cleaner 250 is pressed against the intermediate transfer belt 225 for cleaning by the cleaner 250. On the other hand, if A> B, the blade 251 of the cleaner 250 is separated from the intermediate transfer belt 225 and cleaning is performed by the waste toner recovery unit 260.
When the storage unit 252 of the cleaner 250 reaches the saturation level, the fact that the waste toner of the cleaner 250 is saturated is displayed on the operation panel 205 to prompt the user to replace the storage unit 252. Similarly, when the storage unit 262 of the waste toner recovery unit 260 reaches the saturation level, the operation panel 205 displays that the storage unit 262 of the waste toner recovery unit 260 is saturated, and the user replaces the storage unit 262. Prompt.

Returning to step S142, if the waste toner collection unit 260 is not attached ("NO" in step S142), cleaning is performed using the cleaner 250 (step S145).
Returning to step S143, if it is determined that the waste toner collection unit 260 is saturated (“YES” in step S143), a message prompting replacement of the waste toner collection unit 260 is displayed on the operation panel 205 (step S143). In step S146, cleaning is performed using the cleaner 250 (step S145).

  Returning to step S141, if it is determined that the cleaner 250 is saturated (“YES” in step S141), it is further determined whether the waste toner collection unit 260 is mounted (step S147). If yes (“YES” in step S147), cleaning is performed using the waste toner collection unit 260 (step S148).

On the other hand, if it is determined that the waste toner collection unit 260 is not attached (“NO” in step S147), a message prompting the replacement of the cleaner 250 or the attachment of the waste toner collection unit 260 is displayed on the operation panel 205 (step S149). ).
As described above, the waste toner collecting unit 260 can be mounted in place of the image forming unit 210, so that it is not necessary to replace the container 252 at that time even when the container 252 of the cleaner 250 is saturated. Compared to a configuration having only 250, the number of replacement operations of the storage portion 252 is reduced, and the maintainability is improved.

  In the above description, the control unit 300 determines whether to use the cleaner 250 or the waste toner collection unit 260. For example, a screen (not shown) for accepting designation of the usage method from the user is displayed on the operation panel 205. It is also possible to execute a process of removing the toner by switching between the cleaner 250 and the waste toner collecting unit 260 according to the usage method specified on the screen. In this case, the control unit 300 functions as an accepting unit that accepts designation of the usage method of the cleaner 250 and the waste toner collecting unit 260 when executing the processing, and the cleaner 250 and the waste toner collection according to the accepted usage method. It can be said that the unit 260 functions as switching means for switching and using.

In the above description, the cleaning process is performed every time image formation is performed on one recording sheet. However, the execution timing is not limited to this. For example, it may be executed at a timing such as every time image formation for a plurality of sheets, one page, or a plurality of pages is executed, or every time one or more jobs are completed.
Furthermore, although the cleaning process shown in FIG. 22 and the cleaning process shown in FIG. 23 are used in separate apparatuses, for example, in each apparatus, each process can be arbitrarily selected from the operation panel 205 or an external terminal. It is also good.

FIG. 24 is a diagram showing a schematic configuration of another waste toner recovery unit 270. As shown in FIG.
As shown in the figure, the waste toner collection unit 270 includes a charging roller 271 for recharging the waste toner remaining on the intermediate transfer belt 225 and a collection roller 272 to which the waste toner on the intermediate transfer belt 225 is transferred. A charger 273 for charging the collection roller 272, a blade 275 for scraping the waste toner transferred to the collection roller 272 to the collection unit 274, and the blade 275 at a scraping position and a non-scraping position. A switching motor 276 for switching and an output terminal 277 are provided.

  The waste toner collection mechanism of the waste toner collection unit 270 will be described below. First, since the charge of the waste toner remaining on the intermediate transfer belt 225 after the secondary transfer is broadly distributed, the waste toner is forcibly charged to the negative electrode using the charging roller 271. The waste toner is conveyed to a region sandwiched between the transfer roller 224 and the collection roller 272. Since the collection roller 272 is charged to the positive electrode by the charger 273, waste toner is transferred to the collection roller 272 by applying a negative bias to the transfer roller 224. The recovered waste toner on the recovery roller 272 is scraped off from the recovery roller 272 by the blade 275 and is stored in the waste toner storage unit.

<Modification>
As described above, the present invention has been described based on the embodiment. However, the present invention is not limited to the above-described embodiment, and the following modifications may be considered.
(1) In each image forming mode, if it is determined in advance which image forming unit is optimally mounted in which slot, the optimal state is obtained in the combination of the image forming units mounted. In such a manner, the user is instructed to replace the image forming unit, for example, a message “Please replace each image forming unit installed in slot 1 and slot 2” on the operation panel, and image forming is performed. You can also encourage replacement of units.

In an electrophotographic image forming apparatus, there is a preferred color overlapping order in view of image quality. For example, since the image forming units are preferably in the order of K, C, M, and Y in order from the upstream side, a message or sign that prompts the user to change the mounting position of the image forming unit if not in that order. May be displayed on the operation panel.
Also, it is not preferable to use a combination of a full-color image forming unit and a pseudo full-color image forming unit in consideration of image quality. Therefore, an image forming unit for the full color mode and an image forming unit for the pseudo full-color mode are used. If it is mounted, a message for prompting replacement of the image forming unit may be displayed on the operation panel. Specifically, this is the case where image forming units for each color of Y, M, C ′, and K are mounted.

If the user can be notified, the output of the instruction is not limited to the message display. For example, a method of outputting sound, a method of outputting to a terminal device requesting a job, etc., and displaying on the display can be used.
(2) In the above embodiment, information indicating the image forming mode that can be executed is displayed on the operation panel as a message. However, as long as the user can be notified, the output method of the information is not limited thereto. For example, as described above, a method of outputting the information by voice can be used.
(3) In the above-described embodiment, the configuration example in which four slots (storage units) for mounting the image forming units are described, but the number of storage units is not limited thereto. For example, it can be 5 or more. In this case, for example, one image forming unit for M ′ color, two image forming units for C ′ color, and two image forming units for K color can be mounted. If the two C ′ color image forming units are switched and used as described above, the replacement cycle of the C ′ color image forming unit is extended, and the time required for replacement by the user is reduced accordingly.

In the above, all the image forming units can be attached to and detached from each slot. For example, the image forming units for M, C, and K colors are fixedly arranged in each slot, and the remaining slots Another image forming unit may be configured to be detachable by the user. At least the pseudo full color mode can be executed, and if the Y color image forming unit is mounted in another slot, the full color mode can be executed.
(4) In the above embodiment, an example in which the present invention is applied to a printer has been described. However, the image forming apparatus is not limited to a printer, and can be applied to a copying machine, a FAX, an MFP (Multiple Function Peripheral), and the like. .

Further, the above embodiment and the above modification examples may be combined.
<Image forming method>
The present invention is not limited to the image forming apparatus, and may be an image forming method in the pseudo full color mode or the like. Furthermore, the method may be a program executed by a computer. The program according to the present invention includes, for example, a magnetic disk such as a magnetic tape and a flexible disk, an optical recording medium such as a DVD-ROM, DVD-RAM, CD-ROM, CD-R, MO, and PD, and a flash memory recording medium. It can be recorded on various computer-readable recording media, and may be produced, transferred, etc. in the form of the recording medium, wired and wireless various networks including the Internet in the form of programs, In some cases, the data is transmitted and supplied via broadcasting, telecommunication lines, satellite communications, or the like.

  Further, the program according to the present invention does not have to include all modules for causing the computer to execute the processing described above. For example, a separate information process such as a communication program or a program included in an operating system (OS) is performed. You may make it make a computer perform each process of this invention using the various general purpose programs which can be installed in an apparatus. Accordingly, it is not always necessary to record all the modules on the recording medium of the present invention, and it is not always necessary to transmit all the modules. Further, there are cases where predetermined processing can be executed using dedicated hardware.

  The present invention can be used for an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine thereof.

1 is a diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment. 1 is a diagram illustrating a schematic configuration of an image forming unit 10. FIG. 5 is a diagram showing an example in which an image forming unit 10K is mounted in a slot 6 instead of the image forming unit 10Y. FIG. 4 is a diagram showing an example in which the image forming units 10 are not mounted in some slots 6. FIG. 4 is a chromaticity diagram showing chromaticity points of M and C toners in an L ^* a ^* b ^* color system. 3 is a diagram illustrating a relationship between a combination of image forming units 10 and an executable image forming mode. FIG. 2 is a block diagram illustrating a configuration of a control unit 100. FIG. 3 is a block diagram illustrating a configuration of an image processing unit 103. FIG. 4 is a flowchart showing the contents of a print job executed by the control unit 100. It is a flowchart which shows the content of the mode display process. It is a figure which shows the message screen 111 of the operation panel 5 on which the image formation mode which can be selected was displayed. It is a flowchart which shows the content of the unit determination process 1. FIG. It is a flowchart which shows the content of the unit determination process 2. FIG. It is a flowchart which shows the content of the unit determination process 3. FIG. It is a flowchart which shows the content of the unit determination process 4. FIG. It is a flowchart which shows the content of the unit determination process 1 which concerns on a modification. 10 is a flowchart showing the contents of print processing according to a modification. FIG. 2 is a schematic diagram illustrating a state of an image forming area assigned to each image forming unit 10 for one recording sheet. It is a figure which shows the whole structure of the image forming apparatus which concerns on 2nd Embodiment. 2 is a diagram illustrating a schematic configuration of a waste toner recovery unit 260. FIG. It is a block diagram which shows the structure of the control part 300 which concerns on 2nd Embodiment. 5 is a flowchart showing details of a cleaning process performed by a control unit 300. 10 is a flowchart showing the contents of another cleaning process performed by the control unit 300. FIG. 6 is a diagram showing a schematic configuration of another waste toner recovery unit 270.

Explanation of symbols

1,200 Image forming apparatus 6,206 Storage unit 10 (10Y, 10M, 10C, 10K), 210 Image forming unit 225 Transfer object 250 Cleaner 260, 270 Waste toner collecting unit

Claims (22)

A tandem type image forming apparatus that includes a plurality of image forming units and forms a color image by multiple transfer of toner images of respective colors formed by the respective image forming units onto a transfer target,
It has four or more storage units for storing image forming units,
A first image forming unit for magenta color is stored in the first storage unit, a second image forming unit for cyan color is stored in the second storage unit, and a black image forming unit is stored in the third storage unit. When the third image forming unit is stored,
An image forming apparatus that executes an image forming mode for forming a color image using only the first to third image forming units as the plurality of image forming units.   The image forming apparatus according to claim 1, wherein each of the first to third image forming units is configured to be detachable from the first to third storage units.   A fourth image forming unit different from the first to third image forming units is configured to be detachable from a fourth storage unit different from the first to third storage units. The image forming apparatus according to claim 1 or 2. The fourth image forming unit is one for magenta, cyan and black;
When the fourth image forming unit is stored in the fourth storage unit,
The image forming apparatus according to claim 3, wherein a plurality of image forming units for the same color are switched and used.   Among the plurality of image forming units for the same color, the image is developed using one image forming unit, and when development by the one image forming unit becomes impossible, the image forming unit is switched to another image forming unit. The image forming apparatus according to claim 4, wherein the color is developed.   The image forming apparatus according to claim 4, wherein the plurality of image forming units for the same color are alternately switched. The transfer object is a sheet for recording,
The image forming apparatus according to claim 6, wherein an image forming unit to be used is switched for each sheet. The transfer object is a sheet for recording,
7. The image forming apparatus according to claim 6, wherein when the image forming area for one sheet is divided into a plurality of partial areas, the image forming unit to be used is switched for each partial area. The color image formation is executed on a job basis,
The image forming apparatus according to claim 6, wherein the image forming unit to be used is switched for each job.   5. The image forming apparatus according to claim 4, wherein a designation of a usage method is received for the plurality of imaging units for the same color, and the imaging unit to be used is switched based on the received usage method. . The fourth image forming unit for yellow color is configured to be detachable from a fourth storage unit different from the first to third storage units,
When the fourth image forming unit is stored in the fourth storage unit,
3. The image formation according to claim 1, wherein another image formation mode for forming a color image is executed by using the first to fourth four image forming units instead of the image formation mode. apparatus.   A waste toner recovery unit that recovers residual toner on the one image carrier is detachably attached to a fourth storage unit different from the first to third storage units. Item 3. The image forming apparatus according to Item 1 or 2. A cleaner that collects residual toner on the one image carrier at a position different from each of the storage units;
When the waste toner recovery unit is stored in the fourth storage unit,
The image forming apparatus according to claim 12, wherein the cleaner and the waste toner collecting unit are switched and used.   During the operation of collecting the residual toner by the cleaner, the collection of the residual toner by the waste toner collecting unit is stopped. When the residual toner cannot be collected by the cleaner, the residual toner is collected by the waste toner collecting unit. The image forming apparatus according to claim 13, wherein an operation is started.   The image forming apparatus according to claim 13, wherein the cleaner and the waste toner collecting unit are alternately switched and used.   The image forming apparatus according to claim 13, wherein designation of a usage method of the cleaner and the waste toner recovery unit is received, and the cleaner and the waste toner recovery unit are switched according to the received usage method. In the image forming unit for magenta color, the chromaticity point on the chromaticity diagram is yellow compared to the full-color magenta toner used when forming a color image with four colors of magenta, cyan, yellow, and black. Magenta toner for pseudo full color shifted in a direction approaching the hue of the toner, and / or
The cyan image forming unit has a chromaticity point on the chromaticity diagram that is more yellow than the full-color cyan toner used when forming a color image with four colors of magenta, cyan, yellow, and black. 17. The image forming apparatus according to claim 1, wherein pseudo full-color cyan toner shifted in a direction approaching the hue of the toner is stored.   Before forming a color image, for each combination of image forming units capable of forming a color image in the stored image forming units, an image forming mode corresponding to the combination is obtained and the obtained image forming mode is indicated. The image forming apparatus according to claim 1, wherein information is output.   19. The image forming mode specified in claim 18 is executed instead of the image forming mode when a user specifies a desired image forming mode from among the image forming modes indicated in the output information. The image forming apparatus described.   When there are a plurality of image forming modes indicated in the output information, the designation is accepted, and in one case, the designation is not accepted, and instead of the image forming mode, the single one is accepted. The image forming apparatus according to claim 19, wherein an image forming mode is executed.   19. The image forming apparatus according to claim 18, wherein when the obtained image forming mode is one, the output is not performed and the one image forming mode is executed instead of the image forming mode. . An image forming apparatus that sequentially forms toner images of different colors on a single image carrier using a plurality of image forming units, and forms a color image by multiple transfer of the formed toner images onto a transfer target. An image forming method in which
Of the four or more storage units for storing the image forming units, the first storage unit stores the first image forming unit for magenta color, and the second storage unit stores the second image unit for cyan. When the image forming unit is stored and the third image forming unit for black color is stored in the third storage unit,
An image forming method for executing an image forming mode for forming a color image using only the first to third image forming units as the plurality of image forming units.

Images