JP2007025730A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To execute a monochrome print mode even without attaching all developing units in a color image forming apparatus. <P>SOLUTION: An engine controller detects, stores whether or not the respective developing units are attached and outputs a ready signal to a host computer when a black developing unit is attached (a step S14). Since execution of a monochrome image sequence is permitted if the black developing unit is attached when a monochrome image signal is input from the host computer (a step S18), monochrome print is possible even if developing units in other colors are not necessarily attached. Meanwhile, execution of a color image sequence is permitted only when all the development units are attached when a color image signal is input (a step S21). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a printer, a copying machine, and a facsimile machine, and more particularly to an image forming apparatus in which each of a plurality of developing units can be individually attached to and detached from a unit holding portion.

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

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

  In such an image forming apparatus, all the toner color development units are mounted at predetermined positions in order to quickly respond to printing requests of either color or single color and to obtain a desired color or single color image. (See Patent Document 1).

  Therefore, in the conventional color image forming apparatus, in order to prevent a printing error due to insufficient mounting of the developing unit, if there is a developing unit that is not mounted, the printing operation is prohibited and all the developing units are mounted. It is configured to print only when.

JP 2000-305419 A

  By the way, in the image forming apparatus configured in this way, as described above, the single color printing mode can be executed as necessary. In this single color printing mode, printing is performed using only the single color developing unit. Therefore, it is not necessary to attach the other toner color developing units.

  However, in the above-described conventional image forming apparatus, printing cannot be executed unless all the development units are mounted, regardless of whether the printing mode is the color printing mode or the monochrome printing mode. For this reason, even when the user wants to output only a single color image, the development units for all toner colors must be purchased and installed, and the cost and labor of installation become an excessive burden on the user. Yes.

  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 monochrome printing without mounting all the development units.

  An image forming apparatus according to the present invention is an image forming apparatus that forms an image based on an image signal input from the outside, and in order to achieve the above object, 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 different color toners, and a driving unit that selectively positions one of the plurality of developing units at the developing position. A monochrome printing mode for forming a monochrome toner image by positioning a development unit for toner color for monochrome printing at a development position among the plurality of development units by controlling the driving unit; and a plurality of development units Of these, at least two or more development units are sequentially positioned at the development position to form toner images of different colors to form a color image. Control means for executing a color printing mode, and the control means inputs a status request signal for confirming whether or not image formation is possible prior to input of the image signal from the outside. In this case, only the presence / absence of mounting of the single color printing toner color developing unit is confirmed, and when the mounting of the single color printing toner color developing unit is confirmed, the execution of the single color printing mode is permitted. (Claim 1).

  In the invention configured as described above, the control unit determines whether or not to permit execution of printing in each printing mode according to the mounting state of the developing unit. For example, when a print command for executing single color printing is input from an external device, if a toner color development unit for single color printing is installed, the control means switches to a mounting state of another toner color development unit. Regardless, monochrome printing is permitted and printing is performed.

  In this way, since at least a single color printing toner color development unit is installed, it is configured to permit single color printing with the toner color, so even if no other toner color development unit is installed, this The image forming apparatus can be used as a monochrome printing apparatus.

  Also, for example, when any color toner other than for single color printing is consumed and color printing becomes impossible, the conventional image forming apparatus cannot perform all printing unless the toner is replenished. However, the apparatus of the present invention can continue to be used as a monochromatic printing apparatus as it is.

  If the print command from the outside is to execute color printing, the control means executes printing only when all the color developing units are ready, but there is a developing unit that is not mounted in any one color. In some cases, printing may not be performed. In this case, color printing can be performed only when a development unit for all toner colors is installed, and the lack of toner of any color causes the image to be printed. It is possible to prevent the quality from being impaired.

  Here, the unit holding portion of the image forming apparatus is provided so as to be rotatable 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 attached to the unit holding unit may be moved to the developing position by the rotational driving of the unit holding unit by the driving unit (claim 2).

  In the invention thus configured, each developing unit is sequentially moved to the developing position by the rotation of the unit holding portion, and forms a toner image of each color by facing the photoconductor disposed at the developing position. For this reason, only one developing unit always faces the photoconductor, so that the circumference of the photoconductor can be made small, and the apparatus can be miniaturized.

  In addition, the mounting state of each developing unit can be detected by further including a detecting unit that detects whether or not the developing unit for single color printing toner color is mounted on the unit holding part (claim). Item 3).

  The control means permits the execution of monochrome printing based on a monochrome printing request from the outside of the apparatus when the detection means detects that the toner color developing unit for monochrome printing is attached to the unit holding unit. It is configured. Therefore, it is possible to surely grasp the mounting state of each developing unit and execute a printing mode corresponding to that.

  Also, for users who use this type of image forming apparatus, in many cases, even when using an apparatus capable of color printing, for example, black and white printing using black toner is performed more frequently than color printing. The situation is overwhelmingly high. Therefore, for example, black can be used as the toner color for single color printing.

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

  For this reason, for example, it is unnecessary burden for users who mostly use black and white printing, or for users who want to purchase color printing devices for future use, but only for black and white printing for the time being. It can meet the demand without forcing.

  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. 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 an apparatus for forming a monochrome image (monochrome printing mode) using only the toner. In this image forming apparatus, when an image signal is supplied from an external device such as a host computer to the main controller of the control unit, the engine controller 1 controls each part of the engine unit EG in response to a command from the main controller. Then, an image corresponding to the image signal is formed on a sheet S such as transfer paper, paper, and an OHP transparent sheet.

  In this engine section EG, seven units are: (a) photosensitive unit 2; (b) yellow developing unit 3Y; (c) magenta developing unit 3M; (d) cyan developing unit 3C; (e) black developing unit 3K; (f) The intermediate transfer unit 4 and (g) the fixing unit 5 are detachable from the apparatus main body 6. Then, with all the units 2, 3Y, 3M, 3C, 3K, 4, 5 mounted on the apparatus main body 6, as shown in FIG. 1, the photoconductor 21 of the photoconductor unit 2 is in the direction of the arrow in FIG. The rotary developing unit 3 and the cleaning unit 23 including the charging unit 22, the developing units 3Y, 3M, 3C, and 3K are disposed around the photosensitive member 21 along the rotation direction D1.

  Among the seven units 2, 3 Y, 3 M, 3 C, 3 K, 4, and 5, the photosensitive unit 2 contains a photosensitive member 21, a charging unit 22, and a cleaning unit 23. On the other hand, it is detachable. The charging unit 22 is applied with a charging bias, and uniformly charges the outer peripheral surface of the photoreceptor 21.

  Further, the photosensitive unit 2 is provided with a cleaning unit 23 on the upstream side of the charging unit 22 in the rotational direction D1 of the photosensitive unit 21, and the toner remaining on the outer peripheral surface of the photosensitive unit 21 after the primary transfer. Scrap off. In this way, the surface of the photoreceptor 21 is cleaned.

  A serial EEPROM 71 for storing data indicating the remaining life of the unit 2 is attached to the photoconductor unit 2 configured as described above. When the photoconductor unit 2 is attached to the apparatus main body 6, a connector ( (Not shown) is electrically connected to the engine controller 1 of the apparatus main body 6, performs data transfer with the engine controller 1, performs mounting detection of the photosensitive unit 2, consumables management, and the like. The units 4 and 5 are also provided with serial EEPROMs 76 and 77 for storing various data in the same manner as the photoconductor unit 2, and are electrically connected to the engine controller 1 of the apparatus main body 6 when the units are mounted. Then, data is transferred to and from the engine controller 1 to detect installation of the unit and manage consumables.

  On the other hand, the development units 3Y, 3M, 3C, and 3K are also provided with serial EEPROMs 72 to 75 for storing various data related to the units. 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 necessary. Data transfer between the image forming unit 3 and the image forming unit 3 to detect the attachment of the developing units 3Y, 3M, 3C, and 3K and manage consumables.

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

  The electrostatic latent image formed in this way is developed with toner by the rotary developing unit 3. In the rotary developing unit 3, a black developing unit 3K, a cyan developing unit 3C, a magenta developing unit 3M, and a yellow developing unit 3Y are rotatably provided around the axis. The developing units 3Y, 3M, 3C, and 3K are moved and positioned at a plurality of predetermined positions, and are selectively positioned at the contact or separation positions with respect to the photosensitive member 21, so that a DC component or a DC A developing bias in which an AC component is superimposed on the component is applied to apply toner of a selected color to the surface of the photoreceptor 21. Thus, in this embodiment, each of the developing units 3Y, 3M, 3C, and 3K functions as a “developing unit” of the present invention, and forms a toner image on the photosensitive member 21.

  The toner image developed by the developing unit 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 spanned by a plurality of rollers, and a drive unit (not shown) that rotationally drives the intermediate transfer belt 41, and transfers a color image to the sheet S. The color toner images formed on the photosensitive member 21 are superimposed on the intermediate transfer belt 41 to form a color image (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 single color image (single color 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 formed in this way is conveyed via the fixing unit 5 to a discharge tray portion provided on the upper surface portion of the apparatus main body 6.

  Next, the configuration of the rotary developing unit 3 will be described in more detail with reference to FIG. FIG. 3 is a schematic diagram showing the operation of the rotary developing unit 3.

  The rotary developing unit 3 has a rotating shaft 3a at its center and a support frame 3b fixed to the rotating shaft 3a. The four color developing units 3Y, 3M, 3C, and 3K described above are the present invention. It is detachable from the support frame 3b functioning as a “unit holding portion”. That is, the developing units 3Y, 3M, 3C, and 3K and the support frame 3b are provided with guide rails (not shown) that are engaged with each other in the axial direction. The developing units 3Y, 3M, 3C, and 3K each have a support frame. It can be pulled out to the take-out side in the axial direction 3b (the back side perpendicular to the paper surface of FIG. 1) through the take-out port 321 (FIG. 3). In addition, a new developing unit can be mounted by being advanced in the axial direction of the support frame 3b through the exclusive port 321. When all the developing units 3Y, 3M, 3C, and 3K are mounted in this manner, they are arranged radially about the rotation shaft 3a.

  The take-out port 321 is provided in the side plate 32 arranged on the take-out side of the rotary developing unit 3 as shown in FIG. 3, and for example, as shown in FIG. Only when the developing unit is positioned, the developing unit can be taken out through the take-out port 321 and a new developing unit can be mounted after the taking-out. While the developing unit is positioned at a position other than the exclusive position for taking out, the taking out of the developing unit is restricted by the side plate 32.

  Further, a pulse motor (not shown) is connected to the rotary shaft 3a via a clutch. By driving this pulse motor, the support frame 3b is rotated, and the four developing units 3Y, 3M, 3C, 3K are rotated. One of the developing units can be selectively positioned at a developing position facing the photosensitive member 21. That is, this pulse motor functions as the “driving means” of the present invention. FIG. 1 shows a state in which the black developing unit 3K is positioned at the developing position.

  An HP detection unit 31 (see FIG. 1) for detecting the home position of the developing unit 3 (hereinafter referred to as “HP position”) is provided at one end side (the front side of the sheet of FIG. 1) of the rotating shaft 3a of the developing unit 3. 2) is provided. The HP detection unit 31 includes a signal disc 311 fixed to one end of the rotating shaft 3a and an HP sensor 312 made of a photo interrupter or the like. The peripheral portion of the disc 311 is the HP sensor. It is provided so as to be in the gap 312 (not shown). When the slit portion formed in the disk 311 moves to the gap of the HP sensor 312, the output signal from the HP sensor 312 changes from “L” to “H”. The HP position of the developing unit 3 can be detected based on the signal level change 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 number of pulses of the pulse motor.

  The configuration of the HP detection unit 31 is not limited to this. For example, a feature portion such as a protrusion provided on a part of the outer peripheral edge of the support frame 3b is detected, and thereby the HP position is detected. It may be configured. In this case, there is no need to provide the disc 311 on the rotating shaft 3a, the axial size can be reduced, and this is advantageous in reducing the size of the apparatus.

  Further, connectors 33Y, 33M, 33C, and 33K are fixed to one end side surface of each of the developing units 3Y, 3M, 3C, and 3K. When positioned at the developing position, one downstream side in the rotational movement direction is secured. The connector of the developing unit (for example, as shown in FIG. 3B, when the yellow developing unit 3Y is positioned at the developing position, a connector 33K fixed to the black developing unit 3K on the downstream side thereof is connected to the apparatus main body side. Opposite to the common connector 34 for the developing unit provided. The developing unit common connector 34 is configured to be movable toward and away from the rotary developing unit 3 as shown in the figure, and moves closer to the developing unit one downstream of the developing position as necessary. And engages with the connector of the developing unit. As a result, the EEPROM attached to the developing unit is electrically connected to the engine controller 1 of the apparatus body 6 via both connectors, and data is transferred to and from the engine controller 1 to detect the mounting of the developing unit. Manage consumables.

  Although not shown in the drawings, a lock mechanism is provided to securely position and fix the rotary developing unit 3 at the development position, the HP position, and the take-out dedicated position. Further, the apparatus main body 6 is provided with a front cover that covers the engine unit EG including the units 2, 3Y, 3M, 3C, 3K, 4, and 5 when the user or the like replaces the developing unit described later. In this case, the front cover is opened and the work is performed, but a normal printing operation is executed with the front cover closed.

  Next, the configuration of the engine controller 1 will be described with reference to FIG. The engine controller 1 functions as a “control unit” of the present invention, and controls each part of the apparatus by executing a program to be described later by the CPU 11 based on a signal from the HP detection unit 31 and the number of pulses of the pulse motor. The CPU 11 is connected to a ROM 12 for storing programs and other data, and a RAM 13 for temporarily storing various data.

  The CPU 11 is connected to a serial EEPROM 14 used for an electronic counter via a serial I / F (interface) 15. The serial EEPROM 14 stores data necessary for device control. 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 Y, 3 M connected to the units 2, 4, 5 and the connector 34 as appropriate. Data can be transferred to and from serial EEPROMs 71 to 77 provided in 3C and 3K, and a chip select signal CS can be input to the serial EEPROMs 14 and 71 to 77 via the input / output port 16.

  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 and sends a reset signal indicating that to the CPU 11 and peripheral devices. 15 and 16 are output.

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

  Next, a replacement operation of the developing unit in the image forming apparatus configured as described above 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 of replacing the black developing unit 3K will be described with reference to FIGS. 3 and 4, but the same applies to other toner color developing units.

  In this apparatus, when the user or the like gives an instruction to replace the developing unit, the engine controller 1 executes steps S1 to S9 to execute the replacement process of the black developing unit 3K. First, the pulse motor is driven to rotate the rotary developing unit 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 developing unit common connector 34 on the apparatus main body side.

  In the next step S2, the connector 34 moves to the rotary developing unit 3 side and engages with the connector 33K, and the EEPROM 75 attached to the black developing unit 3K is connected to the engine controller 1 of the apparatus main body 6 via both connectors 33K and 34. Is electrically connected to the EEPROM 75 to read / write data. As a result, data relating to the black developing unit 3K is updated and stored.

  Subsequently, the connector 34 moves backward to the apparatus main body side and is detached from the connector 33K, and retracts to a position where it does not interfere with the rotation operation of the rotary developing unit 3. Thereafter, as shown in FIG. 3C, the pulse motor is driven to rotate the rotary developing unit 3 so that the black developing unit 3K is positioned at the take-out dedicated position (step S3). As a result, the black developing unit 3K can be taken out for the first time. However, removal of the developing units 3C, 3M, and 3Y other than the black developing unit 3K is restricted by the side plate 32. For this reason, it is possible to prevent a user or the like from accidentally taking out a developing unit other than the black developing unit.

  In step S4, the user or the like waits for the black developing unit 3K to be taken out from the rotary developing unit 3 via the take-out port 321 and then to be fitted with a new black developing unit 3K. Here, whether or not the unit has been replaced by the user can be determined by whether or not the front cover has been opened and closed. That is, for example, an opening / closing sensor (not shown) using a limit switch is provided in the apparatus main 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 is completed. . At this time, the user may close the front cover without attaching the developing unit as necessary.

  Thus, when it is detected that the front cover is closed, the yellow developing unit 3Y is positioned to 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 reading / writing of the black developing unit 3K is performed as in step S2. Writing is performed (step S7).

  On the other hand, when the cover is closed without the black developing unit 3K attached, even if the connector 34 moves to the rotary developing unit 33 side, it can be connected to the connector 33K of the black developing unit 3K that should be in that position. Can not. In this case, step S7 is omitted. As described above, the connector 34 performs data transfer 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. The connector 34 and the engine controller 1 function as the “detecting means” of the present invention.

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

  Finally, the pulse motor is driven to rotate the rotary developing unit 3 to position the rotary developing unit 3 at the HP position shown in FIG. 3A and enter a standby state (step S9). Thus, the replacement process of the black developing unit 3K is completed, and a normal image forming operation is executed after waiting for an image signal from an external device such as a host computer.

  As described above, when the replacement of the black developing unit 3K is completed, the EEPROM 14 of the engine controller 1 stores data indicating whether or not the black developing unit 3K is installed and the usage status thereof. The same is true when another developing unit is replaced. Therefore, the engine controller 1 can obtain information on the mounting state and usage status of each developing unit by reading data written in the EEPROM 14 via the serial I / F 15 as needed.

  Next, the operation when an image signal is given from an external apparatus (here, a host computer) to the image forming apparatus in the standby state after the mounting of each developing unit is completed is described with reference to the flowchart of FIG. However, it will be explained.

  The host computer first outputs a status request signal for confirming whether the image forming apparatus is in a printable state (ready state). When the image forming apparatus receives a signal from the host computer (step S11), the contents of this signal are identified. If this signal is a 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 sends a response signal corresponding to the state. Send to host computer.

  Specifically, if the black developing unit 3K is not attached (step S13), neither color nor single color can be printed, so the CPU 11 cannot print to the host computer (not ready). A not-ready signal indicating the presence is returned (step S15). On the other hand, when the black developing unit 3K is attached, at least monochrome printing in black color, that is, the monochrome printing mode can be executed, so the CPU 11 returns a ready signal indicating that the engine unit EG is in a ready state (step S14). Then, the process returns to step S11 to wait for a signal from the host computer.

  The host computer that has received the response from the image forming apparatus transmits a signal (image signal) indicating the image information to be printed subsequently when the response is a ready signal, and the received signal is transmitted to the image forming apparatus side. When it is an image signal (step S16), the following steps S17 to S21 are executed based on the contents.

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

  On the other hand, when the apparatus is in the ready state, it is determined whether the received image signal is compatible with black monochrome printing (step S18). If the image signal corresponds to single color printing, the CPU 11 controls each part of the engine unit EG based on a predetermined single color printing sequence stored in the ROM 12, and sets the black single color printing mode corresponding to the image signal. Execute (Step S19).

  If the apparatus is in a ready state and the image signal is compatible with color printing, the CPU 11 determines from the data stored in the EEPROM 14 each toner of yellow (Y), magenta (M), and cyan (C). It is confirmed whether or not the developing units 3Y, 3M, and 3C corresponding to the colors are mounted (step S20). If any of the development units is not installed, a not ready signal is output (step S15). If all of the development units are installed, the color is determined based on a predetermined color image forming sequence. The print mode is executed (step S21).

As described above, in the image forming apparatus according to the present embodiment, the operation in response to the print command from the host computer is changed 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 single color printing mode nor the color printing mode is permitted. (2) When the black developing unit 3K is installed, the monochrome printing mode is permitted. (3) The black developing unit. In addition to 3K, when all the development units 3Y, 3M, and 3C for yellow, magenta, and cyan are all installed, they are distinguished so as to allow the color printing mode, and the development units 3Y, 3M, 3C, Processing according to the 3K wearing state is executed.

  By performing the image forming process based on such distinction, the image forming apparatus of the present embodiment has the following operational effects.

  First, if at least the black development unit 3K is correctly installed, it is possible to print in black only, so monochrome printing can be performed without installing another toner color development unit. It is. For this reason, for example, it is unnecessary burden for users who mostly use black and white printing, or for users who want to purchase color printing devices for future use, but only for black and white printing for the time being. It can meet the demand without forcing.

  By attaching all the developing units 3Y, 3M, 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 an image signal corresponding to monochrome printing is received from the host computer, black monochrome printing can be performed using the black developing unit 3K.

  Furthermore, even if toner of any color is consumed and color printing cannot be performed, it is not possible to perform all printing, but it is possible to continue monochrome printing with black color. In the meantime, there is no inconvenience that the device cannot be used.

  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-described embodiment, the developing units 3Y, 3M, 3C, and 3K are radially attached around the rotation shaft 3a to form the rotary developing unit 3, and each developing unit is rotated by the rotation of the rotary developing unit 3. Are sequentially moved to the developing position to develop the toner of each color. However, the scope of application of the present invention is not limited to the above-described embodiment. The present invention can also be applied to an image forming apparatus or the like that is fixed side by side and is developed with each toner color at a plurality of development positions on the photoreceptor.

  In the above embodiment, the four developing units are mounted on the support frame 3b. However, the number of developing units is not limited to “4”, and two or more developing units are mounted. The present invention can be applied to all devices.

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

  In the printing process of the above embodiment, the ready / not ready state is distinguished depending on whether or not the black developing unit 3K is installed, and whether or not color printing is possible when the image signal is a color image. In addition to this, for example, when there is a status request from the host computer, the state of the apparatus is classified into a single color ready / color ready / not ready state and responds. Good.

  In the image forming apparatus of the above-described embodiment, it is possible to form a single-color image using only the black color among the four full-color image toners. However, as an apparatus capable of forming a single-color image using other toner colors. Also good.

  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 and prohibits printing. Accordingly, the color image signal may be converted into a black and white image signal, and black and white printing may be executed.

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

  As described above, according to the present invention, the printing operation is permitted as long as a single color printing toner color developing unit is installed. Therefore, even if other toner color developing units are not necessarily installed, the printing operation is permitted. Single color printing with toner color can be performed.

  For example, a user who wants to use an image forming apparatus capable of color printing for single color printing can install and use only the developing unit for the toner color. There is no unnecessary burden of purchasing and mounting, and it becomes a highly convenient device that can be used properly according to the application.

  Furthermore, even if one of the color printing toner colors is consumed and color printing cannot be performed, if the single color printing toner remains, the single color printing can be continued. There is no problem that the apparatus cannot be used until it is refilled.

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 in FIG. 1. FIG. 6 is a diagram schematically illustrating an operation of a rotary developing unit. 3 is a flowchart showing a black developing unit replacement operation in the image forming apparatus of FIG. 1. 2 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 developing part, 3b ... Support frame (unit holding part), 3Y, 3M, 3C, 3K ... Developing unit, 33Y, 33M, 33C, 33K ... (Unit side) ) Connector, 34 ... Common connector for developing unit (detection means)

Claims (4)

In an image forming apparatus that forms an image based on an image signal input from the outside,
A unit holder provided in the apparatus main body;
A plurality of development units configured to be detachable with respect to the unit holding unit and containing different color toners;
Drive means for selectively positioning one development unit of the plurality of development units at a development position;
By controlling the driving means, a single color printing mode in which a single color printing toner color developing unit is positioned at a developing position among the plurality of developing units to form a single color toner image, and at least one of the plurality of developing units. A control unit that executes a color printing mode in which two or more color developing units are sequentially positioned at the developing position to form toner images of different colors and form a color image;
When the status request signal for confirming whether or not image formation is possible prior to the input of the image signal, the control means receives the toner color for monochrome printing. An image forming apparatus characterized by checking only whether or not a developing unit is mounted, and permitting execution of the monochrome printing mode when the mounting of the developing unit of the toner color for single color printing is confirmed. The unit holding part is provided to be rotatable around a predetermined rotation axis with respect to the apparatus main body,
The plurality of developing units can be attached to the unit holding portion radially about the rotation axis, and the developing unit attached to the unit holding portion can be driven by rotation of the unit holding portion by the driving means. The image forming apparatus according to claim 1, wherein the image forming apparatus is moved to the development position. A detecting means for detecting whether or not the single color printing toner color developing unit is mounted on the unit holding portion;
The control means executes the monochrome printing mode based on a monochrome printing request from the outside of the apparatus when the detection means detects that the toner unit for monochrome printing is mounted on the unit holding unit. The image forming apparatus according to claim 1. The image forming apparatus according to claim 1, wherein the toner color for monochrome printing is black.

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