JP2003043773A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a monochrome printing mode even when not all the developing units are attached in a color image forming device. SOLUTION: An engine controller detects and stores whether each developing unit is attached, and outputs a ready signal to a host computer if the black developing unit is attached (step S14). When a black-and-white image signal is inputted from the host computer (step S18), the performance of monochrome image sequence is permitted if the black developing unit is attached (step S19), so that monochrome printing is performed even though all the other color developing units are not attached. Meanwhile, when a color image signal is inputted, the performance of color image forming sequence is permitted only when all the developing units are attached (step S21).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, a copying machine and a facsimile machine, and more particularly,
The present invention relates to an image forming apparatus in which each of a plurality of developing units can be individually attached to and detached from a unit holder.

[0002]

2. Description of the Related Art As an image forming apparatus of this type, there is known an apparatus including a rotary developing section in which a plurality of developing units are radially arranged around a rotation axis. In this apparatus, one of the plurality of developing units is positioned to face the photoconductor by rotating the rotation shaft of the device, the latent image on the photoconductor is developed, and the latent image is transferred onto the intermediate transfer medium. . Then, if necessary, the rotary developing unit is rotationally driven to switch the developing unit, and the toner development and transfer processing are repeated for each toner color in the same manner as described above, whereby toner images of a plurality of colors are transferred onto the intermediate transfer medium. To form a color image by overlapping (color printing mode).

Further, in the image forming apparatus constructed as described above, it is possible to perform monochromatic printing by using a specific developing unit among a plurality of developing units, in many cases a black developing unit. Print mode).

In such an image forming apparatus, all the developing units for each toner color are set at predetermined positions in order to promptly respond to a print request of color or single color and obtain a desired color or single color image. Must be installed.

Therefore, in the conventional color image forming apparatus,
In order to prevent printing mistakes due to improper installation of development units, the printing operation is prohibited when there are development units that are not installed, and printing is executed only when all development units are installed. ing.

[0006]

By the way, in the image forming apparatus constructed as described above, as described above, it is possible to execute the monochromatic printing mode, and in the monochromatic printing mode, the monochromatic printing mode is executed. Since the printing is performed using only the developing unit of No. 2, it is not necessary to originally attach the developing units of other toner colors.

However, in the above-described conventional image forming apparatus, regardless of the color printing mode or the monochromatic printing mode, printing cannot be executed unless all the developing units are mounted. Therefore, even if the user wants to output only a single-color image, he or she must purchase and install the developing units for all the toner colors, and the cost and the labor of the mounting become an excessive burden on the user. There is.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus capable of monochromatic printing without mounting all developing units.

[0009]

In order to achieve the above-mentioned object, an image forming apparatus according to the present invention comprises a unit holding portion provided in the main body of the apparatus and a detachable structure with respect to the unit holding portion. A plurality of developing units containing toners of different colors, a driving unit for selectively positioning one of the plurality of developing units at a developing position, and a plurality of the plurality of developing units by controlling the driving unit. A monochromatic printing mode in which a monochromatic printing toner color developing unit among the developing units is positioned at the developing position to form a monochromatic toner image, and at least two or more developing units of the plurality of developing units are sequentially moved to the developing position. And a control unit that executes a color printing mode in which toner images of different colors are formed to form color images. The control means permits execution of the monochromatic printing mode when at least the monochromatic printing toner color developing unit of the plurality of developing units is attached to the unit holding portion (claim 1). 1).

In the invention thus constructed, the control means determines whether or not to permit printing in each printing mode, depending on the mounting state of the developing unit. For example, when a print command to execute single-color printing is input from an external device and a developing unit for a toner color for single-color printing is installed, the control unit causes the developing unit for another toner color to be installed. Regardless of that, monochrome printing is permitted and printing is executed.

As described above, if at least a developing unit for a toner color for monochromatic printing is mounted, monochromatic printing with the toner color is permitted. Therefore, a developing unit for another toner color is not mounted. Also, this image forming apparatus can be used as a monochromatic printing apparatus.

Further, for example, when toner of any color other than that for monochromatic printing is consumed and color printing becomes impossible, in the conventional image forming apparatus, all printing is performed unless this toner is replenished. Although no longer possible, the device of the present invention can continue to be used as a monochromatic printing device.

If the print command from the outside indicates that color printing is to be executed, the control means executes the printing only when the developing units for all colors are available, but any one color is not installed. It may be configured not to perform printing when there is a developing unit. In this case, color printing can be executed only when the developing unit for all toner colors is installed, so that there is a lack of toner of any color. This makes it possible to prevent the quality of the image from being impaired.

Here, the unit holding portion of the image forming apparatus is provided rotatably around a predetermined rotation axis with respect to the apparatus main body, and the plurality of developing units are radially arranged around the rotation axis. The developing unit mounted on the unit holding section may be moved to the developing position by rotational driving of the unit holding section by the driving unit (claim 9). 2).

In the invention thus constructed, each developing unit is sequentially moved to the developing position by the rotation of the unit holding portion, and the toner image of each color is formed by facing the photoconductor arranged at the developing position. . Therefore, only one developing unit faces the photoconductor at all times, and the peripheral length of the photoconductor can be reduced, and the size of the apparatus can be reduced.

Further, the mounting state of each developing unit can be detected by further comprising detecting means for detecting whether or not the developing unit for the toner color for monochromatic printing is mounted on the unit holding portion. There is (claim 3).

Then, the control means executes the monochromatic printing based on the monochromatic printing request from the outside of the apparatus when the detection means detects that the developing unit for the monochromatic printing toner color is mounted on the unit holding portion. It is configured to allow. Therefore, it is possible to reliably grasp the mounting state of each developing unit and execute the print mode corresponding thereto.

In many cases, even if a user who uses this type of image forming apparatus uses a device capable of color printing, black-and-white printing using black toner, for example, is more effective than color printing. In reality, the frequency of doing it is overwhelmingly high. Therefore, for example, black can be used as the monochromatic printing toner color (claim 4).

At this time, in an image forming apparatus capable of color printing, by mounting a developing unit containing at least black toner, it is possible to perform black and white printing which is frequently used.

Therefore, for example, for a user who is mostly used for black-and-white printing, or for a user who only performs black-and-white printing for the time being but wants to purchase a device capable of color printing for future use, It is possible to meet the demand without imposing an unnecessary burden.

[0021]

1 is a diagram showing one embodiment of an image forming apparatus according to the present invention. FIG. 2 is a block diagram showing an engine controller of the image forming apparatus of FIG. This image forming apparatus forms a full-color image (color printing mode) by superposing four color toners of yellow (Y), magenta (M), cyan (C), and black (K), or black (K). This is a device that forms a single-color image using only the toner (1) (single-color printing mode). In this image forming apparatus, when an image signal is given to the main controller of the control unit from an external device such as a host computer, the engine controller 1 controls each section of the engine section EG in response to a command from the main controller to copy paper. , An image corresponding to the image signal is formed on a sheet S such as a transfer sheet, a sheet and a transparent sheet for OHP.

In this engine section EG, seven units are provided: (a) photoconductor unit 2; (b) yellow developing unit 3
Y; (c) Magenta developing unit 3M; (d) Cyan developing unit 3C; (e) Black developing unit 3K; (f) Intermediate transfer unit 4 and (g) Fixing unit 5 are detachable from the apparatus main body 6. Has become. Then, in a state where all the units 2, 3Y, 3M, 3C, 3K, 4 and 5 are attached to the apparatus main body 6, as shown in FIG.
1 rotates in the direction of arrow D1 in FIG. 1, and the charging unit 22, the developing units 3Y, 3M, 3C, and 3K around the photoreceptor 21 along the rotation direction D1.
Rotary developing section 3 and cleaning section 23
Are arranged respectively.

Seven units 2, 3Y, 3M, 3C, 3
Among K, 4, and 5, the photoconductor unit 2 contains the photoconductor 21, the charging unit 22, and the cleaning unit 23.
These can be integrally attached to and detached from the apparatus body 6. A charging bias is applied to the charging unit 22 to uniformly charge the outer peripheral surface of the photoconductor 21.

Further, the photoconductor unit 2 is provided with a cleaning unit 23 on the upstream side of the charging unit 22 in the rotation direction D1 of the photoconductor 21, and remains attached to the outer peripheral surface of the photoconductor 21 after the primary transfer. Scrape off any toner that is still on.
In this way, the surface of the photoconductor 21 is cleaned.

A serial EEPROM 71 for storing data indicating the remaining life of the photoconductor unit 2 is attached to the photoconductor unit 2 constructed as described above. , Is electrically connected to the engine controller 1 of the apparatus main body 6 via a connector (not shown),
Data is transferred between the photosensor unit 2 and the device, and detection of mounting of the photoconductor unit 2 and management of consumables are performed. Similar to the photoconductor unit 2, serial EEPROMs 76 and 77 for storing various data are attached to the units 4 and 5, respectively, and are electrically connected to the engine controller 1 of the apparatus main body 6 in a unit mounted state. Then, data transfer is performed with the engine controller 1 to detect the mounting of the unit and manage consumables.

On the other hand, the developing units 3Y, 3M, 3C, 3
The K is also provided with serial EEPROMs 72 to 75 for storing various data relating to the unit.
As will be described later, these EEPROMs 72 to 75 are not connected to the connector 34 on the apparatus main body 6 side in the unit mounted state, but are temporarily electrically connected to the engine controller 1 as needed, and the engine controller 1
Data transfer between the developing units 3Y, 3M,
Detects 3C and 3K installation and manages consumables.

In this image forming apparatus, as shown in FIG. 1, the exposure unit 8 irradiates the outer peripheral surface of the photoconductor 21 charged by the charging unit 22 with the laser beam L. The exposure unit 8 scans and exposes the laser light L on the photoconductor 21 according to the image signal from the engine controller 1 to form an electrostatic latent image on the photoconductor 21 corresponding to the image signal.

The electrostatic latent image thus formed is developed with toner by the rotary developing section 3. In the rotary developing section 3, a developing unit 3K for black, a developing unit 3C for cyan, a developing unit 3M for magenta,
Also, a yellow developing unit 3Y is provided rotatably around the axis. And these developing units 3
Y, 3M, 3C, and 3K are moved and positioned at a plurality of predetermined positions, and are selectively positioned at the contact or separation position with respect to the photoconductor 21 to superpose a DC component or an AC component on the DC component. The developing bias is applied to apply the selected color toner to the surface of the photoconductor 21. As described above, in this embodiment, each of the developing units 3Y, 3M, 3C, and 3K functions as the “developing unit” of the invention, and forms a toner image on the photoconductor 21.

The toner image developed by the developing section 3 as described above is primarily transferred onto the intermediate transfer belt 41 of the intermediate transfer unit 4 in the primary transfer region TR1. That is, the intermediate transfer unit 4 includes an intermediate transfer belt 41 that is wound around a plurality of rollers, and a drive unit (not shown) that rotationally drives the intermediate transfer belt 41, and when transferring a color image to the sheet S. To form a color image by superposing the toner images of the respective colors formed on the photoconductor 21 on the intermediate transfer belt 41 (color printing mode). On the other hand, when transferring a single color image to the sheet S, Only the black toner image formed on the body 21 is transferred onto the intermediate transfer belt 41 to form a monochromatic image (monochromatic printing mode).

The image thus formed on the intermediate transfer belt 41 is secondarily transferred onto the sheet S taken out from the cassette 9 in a predetermined secondary transfer region TR2. Further, the sheet S on which the image is thus formed is conveyed to the discharge tray portion provided on the upper surface of the apparatus main body 6 via the fixing unit 5.

Next, the structure of the rotary developing section 3 will be described in more detail with reference to FIG. FIG. 3 is a schematic view showing the operation of the rotary developing section 3.

The rotary developing section 3 has a rotary shaft 3a at its center and a support frame 3b fixed to the rotary shaft 3a, and the above-described four color developing units 3Y, 3M, 3C, 3K. Is attachable to and detachable from the support frame 3b that functions as the "unit holding portion" of the present invention. That is, the developing units 3Y, 3
M, 3C, 3K and the support frame 3b are provided with guide rails (not shown) that engage with each other in the axial direction, and the developing units 3Y, 3M, 3C, 3K are taken out in the axial direction of the support frame 3b. It is possible to pull out to (the depth side orthogonal to the paper surface of FIG. 1) through the outlet port 321 (FIG. 3). Further, a new developing unit can be mounted by advancing in the axial direction of the support frame 3b through the exclusive outlet 321. When all the developing units 3Y, 3M, 3C and 3K are mounted in this way, they are arranged radially around the rotation shaft 3a.

As shown in FIG. 3, the take-out port 321 is provided on the side plate 3 disposed on the take-out side of the rotary developing section 3.
2 is provided, and the developing unit is taken out through the taking-out port 321 only when the developing unit is positioned at the taking-out exclusive position as shown in FIG. A development unit can be installed. Then, while the developing unit is positioned at a position other than the taking-out exclusive position, taking-out of the developing unit is restricted by the side plate 32.

A pulse motor (not shown) is connected to the rotary shaft 3a via a clutch, and the drive of the pulse motor causes the support frame 3b to rotate, whereby the four developing units 3Y, 3M, One of the developing units 3C and 3K can be selectively positioned at the developing position facing the photoconductor 21. That is, this pulse motor functions as the "driving means" of the present invention. Note that FIG. 1 shows a state where the black developing unit 3K is positioned at the developing position.

Further, at one end side of the rotary shaft 3a of the developing unit 3 (front side of the paper surface of FIG. 1), H for detecting the home position position of the developing unit 3 (hereinafter referred to as "HP position").
A P detector 31 (FIG. 2) is provided. The HP detection unit 31 is composed of a signal disk 311 fixed to one end of the rotating shaft 3a and an HP sensor 312 including a photo interrupter, and the peripheral edge of the disk 311 is H.
It is provided so as to come into the gap (not shown) of the P sensor 312. When the slit formed on the disc 311 moves into the gap of the HP sensor 312, the output signal from the HP sensor 312 changes from “L” to “H”. Then, the HP position of the developing unit 3 can be detected based on the change in the signal level and the pulse number of the pulse motor. Further, the position of the developing unit 3 can be detected based on the HP position and the pulse number of the pulse motor.

The structure of the HP detection unit 31 is not limited to this, and for example, a characteristic portion such as a protrusion provided on a part of the outer peripheral edge of the support frame 3b is detected, and H
It may be configured to detect the P position. In this case, it is not necessary to provide the rotating shaft 3a with the disc 311 and the size in the axial direction can be reduced, which is advantageous in reducing the size of the device.

Further, each developing unit 3Y, 3M, 3C,
Connectors 33Y, 33M, 33 are provided on one end side surface of 3K.
C and 33K are fixed, and when positioned at the developing position, the connector of the developing unit one downstream side in the rotational movement direction (for example, the yellow developing unit 3Y is positioned at the developing position as shown in FIG. 3B). Then, the one connector 33K fixed to the black developing unit 3K on the downstream side faces the developing unit common connector 34 provided on the apparatus main body side. As shown in the figure, the common connector 34 for the developing unit is configured to be movable in and out of contact with the rotary developing unit 3, and if necessary, can move close to the developing unit located one downstream of the developing position. And fit with the connector of the developing unit. As a result, the EEPROM mounted on the developing unit is electrically connected to the engine controller 1 of the apparatus main body 6 via both connectors, and data transfer is performed with the engine controller 1 to detect the mounting of the developing unit. Consumables management etc.

Although not shown in the drawings, a lock mechanism is provided in order to securely position and fix the rotary developing section 3 at the developing position, the HP position, and the take-out exclusive position. Further, the apparatus main body 6 is provided with a front cover for covering the engine portion EG including the units 2, 3Y, 3M, 3C, 3K, 4, 5, and when a user or the like replaces a developing unit described later. Open this front cover for work, but normal printing operation is
It is executed with this front cover closed.

Next, the structure of the engine controller 1 will be described with reference to FIG. The engine controller 1 functions as the "control means" of the present invention, and controls the respective parts of the apparatus by executing a program, which will be described later, by the CPU 11 based on the signal from the HP detector 31, the pulse number of the pulse motor, and the like. The CPU 11 has an RO for storing programs and other data.
An M12 and a RAM 13 for temporarily storing various data are connected.

The CPU 11 is also connected via a serial I / F (interface) 15 to a serial EEPROM 14 used for an electronic counter. The serial EEPROM 14 stores data necessary for controlling the device. Further, the CPU 11 is connected to the units 2, 4, 5 and the connector 34 via the serial I / F 15, and the developing units 3 appropriately connected to the units 2, 4, 5 and the connector 34.
Serial EEPROM provided in Y, 3M, 3C, and 3K
It becomes possible to transfer data between M71-77 and
Serial EEPROM 14 via input / output port 16,
The chip select signal CS can be input to 71 to 77.

Further, the engine controller 1 is provided with a voltage monitoring circuit 17, and when the power supply voltage falls below a predetermined voltage, the voltage monitoring circuit 17 detects the voltage drop,
A reset signal indicating that effect is sent to the CPU 11 and the peripheral device 1.
Output to 5 and 16.

Further, the CPU 11 is connected to the HP detector 31 via the input / output port 16.

Next, the replacement operation of the developing unit in the image forming apparatus thus constructed will be described. FIG. 4 is a flowchart showing the operation of the engine controller 1 during the replacement operation. Here, as an example, the case where the black developing unit 3K is replaced will be described with reference to FIGS. 3 and 4, but the same applies to developing units for other toner colors.

In this apparatus, when the user gives an instruction to replace the developing unit, the engine controller 1 executes steps S1 to S9 to execute the replacing process of the black developing unit 3K. First, the pulse motor is driven to rotationally move the rotary developing section 3 to position the yellow developing unit 3Y at the developing position (step S1). As a result, as shown in FIG. 3B, the connector 33K of the black developing unit 3K faces the common connector 34 for the developing section on the apparatus main body side.

In the next step S2, the connector 34 is moved to the rotary developing section 3 side and fitted with the connector 33K,
EEPRO attached to the black development unit 3K
The M75 is electrically connected to the engine controller 1 of the apparatus body 6 via both connectors 33K and 34, and the EEPR
Read / write data to / from the OM 75.
As a result, the data relating to the black developing unit 3K is updated and stored.

Following this, the connector 34 is moved backward toward the main body of the apparatus, removed from the connector 33K, and retracted to a position where it does not interfere with the rotary operation of the rotary developing section 3. After that, as shown in FIG. 3C, the pulse motor is driven to rotationally move the rotary developing section 3 to position the black developing unit 3K at the exclusive extraction position (step S3). As a result, the black developing unit 3K can be taken out for the first time. However, the developing units 3C, 3M, 3 other than the black developing unit 3K
As for Y, the take-out is restricted by the side plate 32. Therefore, it is possible to prevent the user or the like from accidentally taking out the developing unit other than the black developing unit.

Then, in step S4, the black developing unit 3K is taken out of the rotary developing section 3 through the taking-out exclusive port 321 by the user or the like, and thereafter, a new black developing unit 3K is mounted. here,
Whether or not the unit has been replaced by the user is
It can be determined whether or not the front cover has been opened / closed. That is, an opening / closing sensor (not shown) such as a limit switch is provided in the apparatus body 6, and when the opening / closing sensor detects that the front cover is closed by the user, it can be determined that the replacement work has been completed. . At this time, the user may close the front cover without mounting the developing unit, if necessary.

Thus, when it is detected that the front cover is closed, the yellow developing unit 3Y is positioned at the developing position in the same manner as in step S1 (step S5). Then, when the connector 34 moves to the rotary developing unit 33 side and engages with the connector 33K of the newly installed black developing unit 3K (step S6), the data regarding the black developing unit 3K is read / read as in step S2. Writing is performed (step S7).

On the other hand, when the cover is closed without mounting the black developing unit 3K, the connector 34
Even if it moves to the rotary developing unit 33 side, it cannot be connected to the connector 33K of the black developing unit 3K which should be in that position. In this case, the above step S
7 is omitted. As described above, the connector 34 transfers data to the EEPROMs 72 to 75 provided in each developing unit, and the engine controller 1 performs data collation to detect whether each developing unit is mounted or not. The connector 34 and the engine controller 1 function as the "detection means" of the present invention.

Next, the data relating to the black developing unit 3K is written in the EEPROM 14 provided in the engine controller 1. However, when the black developing unit 3K is not attached, the data indicating that is written in the EEPROM 14. (Step S8).

Finally, the pulse motor is driven to rotationally move the rotary developing unit 3 to move the rotary developing unit 3 to the position shown in FIG.
The robot is positioned at the HP position shown in (a) and enters a standby state (step S9). Thus, the black developing unit 3
The normal image forming operation is executed after the K exchange processing is completed and an image signal is given from an external device such as a host computer.

In this way, when the replacement of the black developing unit 3K is completed, the EE of the engine controller 1
The PROM 14 stores data indicating whether or not the black developing unit 3K is attached and the usage status thereof, and this is the same when replacing the other developing units. Therefore, the engine controller 1
Can read the data written in the EEPROM 14 via the serial I / F 15 as needed to obtain information on the mounting state and the use state of each developing unit.

Next, the operation when an image signal is given from the external device (here, the host computer) to the image forming apparatus in the standby state after the mounting of the developing units is completed in this way, is shown in FIG. This will be described with reference to the flowchart.

The host computer first outputs a status request signal for confirming whether the image forming apparatus is in a printable state (ready state). Upon receiving the signal from the host computer (step S11), the image forming apparatus side identifies the content of this signal. Then, if this signal is the status request signal (step S12), the CPU 11 reads the data relating to each developing unit stored in the EEPROM 14, confirms the mounting state of each developing unit, and outputs a response signal corresponding to the state. Send to host computer.

Specifically, if the black developing unit 3K is not installed (step S13), neither color nor monochrome printing can be performed, so the CPU 11 cannot print to the host computer (not ready). A not ready signal indicating that the state is) is returned (step S15). On the other hand, black development unit 3K
When is installed, at least monochrome printing with black color, that is, monochrome printing mode can be executed.
The CPU 11 returns a ready signal indicating that the engine section EG is in the ready state (step S14). Then, the process returns to step S11, and waits for a signal from the host computer.

When the host computer receives the response from the image forming apparatus in this way, when the response is a ready signal,
Signal indicating image information to be printed subsequently (image signal)
When the received signal is an image signal (step S16), the image forming apparatus side executes the following steps S17 to S21 based on the content thereof.

First, when the image forming apparatus is in the not ready state (for example, the black developing unit 3K is not mounted) when the image signal is received, the CPU 11 outputs the not ready signal to the host computer (step). S15).

On the other hand, when the apparatus is in the ready state, it is judged whether or not the received image signal corresponds to black monochromatic printing (step S18). If the image signal corresponds to monochromatic printing, the CPU 11
Controls each part of the engine section EG based on a predetermined monochromatic printing sequence stored in the ROM 12 to execute the black monochromatic printing mode according to the image signal (step S).
19).

If the apparatus is in the ready state and the image signal corresponds to color printing, the CPU 1
First, from the data stored in the EEPROM 14, it is confirmed whether or not the developing units 3Y, 3M and 3C corresponding to the respective toner colors of yellow (Y), magenta (M) and cyan (C) are attached (step S20). ). And
If one of the developing units is not installed,
A not ready signal is output (step S15), and when all the developing units are mounted, the color print mode is executed based on a predetermined color image forming sequence (step S21).

As described above, the image forming apparatus of this embodiment changes the operation in response to the print command from the host computer according to the mounting state of the developing units 3Y, 3M, 3C and 3K. That is, (1) when the black developing unit 3K is not installed, neither the monochromatic printing mode nor the color printing mode is permitted. (2) when the black developing unit 3K is installed, the monochromatic printing mode is permitted (3) black In addition to the developing unit 3K, yellow, magenta, and cyan developing units 3Y, 3
When all M and 3C are installed, the developing units 3Y, 3M, 3C, and
The process according to the mounting state of 3K is executed.

By performing the image forming processing based on such a distinction, the image forming apparatus of this embodiment has the following operational effects.

First, at least the black developing unit 3
If K is installed correctly, black single-color printing operation is possible, so black-and-white printing can be performed without installing a developing unit for another toner color. Therefore, for example, for users who mostly use black-and-white printing, or for users who only perform black-and-white printing for the time being but want to purchase a color-printable device for future use, it is an unnecessary burden. You can meet the demand without compelling.

Then, all the developing units 3Y, 3M,
By mounting 3C and 3K, it can be used as a full-color image forming apparatus as in the conventional apparatus. Of course, even in this state, when the image signal corresponding to the monochromatic printing is received from the host computer, the black monochromatic printing can be performed by using the black developing unit 3K.

Further, even if the toner of any color is consumed and color printing cannot be performed, not all printing is stopped due to this, but monochromatic printing of black color can be continuously performed. There is no inconvenience that the device cannot be used until the toner is replenished.

The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above embodiment, each developing unit 3Y,
3M, 3C, and 3K are radially mounted around the rotary shaft 3a to form a rotary developing unit 3, and by the rotation of the rotary developing unit 3, each developing unit is sequentially arranged.
I moved to the development position and developed toner of each color,
The application target of the present invention is not limited to the above-described embodiment, and other than this, for example, each developing unit is arranged and fixed around the photoconductor, and each toner color is applied at a plurality of developing positions on the photoconductor. The present invention can also be applied to an image forming apparatus or the like in which the development is performed.

Further, in the above embodiment, four developing units are mounted on the support frame 3b, but the number of developing units is not limited to "4", and two or more developing units are provided. The present invention can be applied to all mounted devices.

In the above embodiment, the developing units 3Y, 3M, 3C and 3K are detachable in the axial direction of the rotary developing section 3, but the developing units are detachable in the radial direction of the rotary developing section 3. The present invention can also be applied to an image forming apparatus according to the present invention.

In the printing process of the above embodiment, the ready / not-ready state is distinguished by whether or not the black developing unit 3K is installed, and color printing is possible when the image signal is a color image. It is determined whether or not there is, but in addition to this, when a status request is made from the host computer, for example, the status of the device is divided into a single color ready / color ready / not ready status to respond. You may

In the image forming apparatus of the above embodiment,
Although it is possible to form a single-color image using only black color among the four full-color image toners, a device that can form a single-color image using another toner color may be used.

In the above embodiment, when a color image signal is input in a state where only monochrome printing is possible, the CPU returns a not-ready signal to the host computer to prohibit printing, but at this time, for example, Alternatively, the color image signal may be converted into a monochrome image signal if necessary, and monochrome printing may be executed.

Further, the image forming apparatus according to the above embodiment is a printer that prints an image provided from an external device such as a host computer on a sheet such as copy paper, transfer paper, paper and OHP transparent sheet. The present invention can be applied to all electrophotographic image forming apparatuses including copiers and facsimile machines.

[0072]

As described above, according to the present invention, the printing operation is permitted as long as the developing unit for the toner color for monochromatic printing is installed, so that the developing units for other toner colors are not necessarily installed. Even if the toner color is not used, monochromatic printing can be performed with the toner color.

Then, for example, for a user who wants to use an image forming apparatus capable of color printing for monochromatic printing, it is possible to mount and use only the developing unit for the toner color, and therefore, it is possible to use other toner colors. It is a highly convenient device that does not impose an unnecessary burden of purchasing and installing a developing unit, and can be used properly according to the purpose.

Further, even when one of the color printing toner colors is consumed and color printing cannot be performed, the single color printing can be continued if the single color printing toner remains. The problem that the device cannot be used until the toner is replenished does not occur.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a block diagram showing an engine controller of the image forming apparatus of FIG.

FIG. 3 is a diagram schematically showing an operation of a rotary developing section.

FIG. 4 is a flowchart showing a black developing unit replacement operation in the image forming apparatus of FIG.

5 is a flowchart showing a printing operation in the image forming apparatus of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine controller (control means, detection means) 3 ... Rotary development part 3b ... Support frame (unit holding part) 3Y, 3M, 3C, 3K ... Development unit 33Y, 33M, 33C, 33K ... (unit side) connector 34 ... Common connector for developing unit (detection means)

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H027 DA27 ED08 EH06 FA28                 2H030 AD06 AD16 BB02 BB24 BB25                       BB33 BB42                 2H071 BA03 BA13 BA17 DA08 DA31                       EA04 EA18                 2H077 AD14 BA08 BA09 BA10 DA24                       DB25 GA13

Claims (4)

[Claims] 1. A unit holding unit provided in the apparatus main body, a plurality of developing units configured to be detachable from the unit holding unit and containing toners of different colors, and a plurality of the developing units. Driving means for selectively positioning one of the developing units at the developing position, and controlling the driving means to position the developing unit for the monochromatic printing toner color among the plurality of developing units at the developing position. A single-color printing mode for forming a single-color toner image and at least two or more developing units of the plurality of developing units are sequentially positioned at the developing position to form toner images of different colors to form a color image. And a control unit that executes a color printing mode, wherein the control unit is configured to perform at least the monochromatic printing among the plurality of developing units. When the toner color of the developing unit is mounted on the unit support, an image forming apparatus and permits the execution of the monochrome printing mode. 2. The unit holding portion is provided rotatably around a predetermined rotation axis with respect to the apparatus main body, and the plurality of developing units are radially arranged on the unit holding portion around the rotation axis. The image forming apparatus according to claim 1, wherein the image forming apparatus is mountable, and the developing unit attached to the unit holding unit is moved to the developing position by rotational driving of the unit holding unit by the driving unit. 3. A detection unit for detecting whether or not the monochromatic printing toner color developing unit is mounted on the unit holding portion, wherein the control unit is configured to detect the monochromatic printing toner color by the detection unit. 3. The image forming apparatus according to claim 1, wherein when it is detected that the developing unit is attached to the unit holding unit, the single color printing mode is executed based on a single color printing request from the outside of the apparatus. 4. The image forming apparatus according to claim 1, wherein the monochromatic printing toner color is black.