JP2007286287A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a monochrome-dedicated mode in addition to a color mode and preventing a color toner cartridge from being consumed or deteriorated, when it is used in the monochrome-dedicated mode. <P>SOLUTION: The image forming apparatus has a plurality of cartridge-attaching parts 50, to which toner cartridges 181 to 184 having a developing part 4 and an image carrier 3 are attached; a transfer body 2, to which the toner image is transferred by press-contacting with the image carrier of the toner cartridge attached to the cartridge attaching part, while traveling; transfer body support means 231 to 234 supporting the transfer body to freely contact with and separate from the image carriers of the respective toner cartridges; and an operation mode setting means 41, capable of setting the color mode and the monochrome-dedicated mode. When the color mode is set as the operating mode, the transfer body is set to a press-contacting mode in which it press-contacts against all the image carriers; and when the monochrome dedicated mode is set as the operating mode, the transfer body is set to a separation mode, in which it press-contacts against only the image carrier of the monochrome toner cartridge. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine and an electrophotographic printer capable of setting a monochrome only mode in addition to a color mode as an operation mode, and more particularly to a tandem type image forming apparatus.

  Conventionally, an image forming apparatus called a tandem type is known as one of color image forming apparatuses.

  As an example, this image forming apparatus has four cartridge mounting portions on which a toner cartridge having a developing portion and an image carrier on which a toner image of a corresponding color is formed by the developing portion is mounted. In each cartridge mounting portion, cyan, magenta, and yellow color toner cartridges and a monochrome toner cartridge are mounted.

  Further, an intermediate transfer belt is provided so as to be able to run facing the toner cartridge, and the intermediate transfer belt is pressed against the image carrier of each cartridge while the intermediate transfer belt is running to transfer the toner image of each image carrier to the intermediate transfer belt. Then, the transferred image is secondarily transferred onto a sheet after being transferred in a superimposed state.

  By the way, in such a conventional tandem type color image forming apparatus, color printing cannot be performed unless all four color toner cartridges are mounted in the correct position, and the monochrome toner cartridge must be mounted in the correct position. Monochrome printing was not possible.

Therefore, in order to solve the above inconvenience, Patent Document 1 discloses an image forming apparatus that accepts monochrome printing if monochrome printing is possible even if color printing is impossible.
JP 2004-45905 A

  However, in the image forming apparatus described in Patent Document 1, only the monochrome toner cartridge is used for monochrome printing, but the intermediate transfer belt is pressed against the image carrier of another color toner cartridge. For this reason, the developing unit of the color toner cartridge has to be rotated, and the toner cartridge is consumed and deteriorated accordingly.

  The present invention has been made in order to eliminate such drawbacks, and is an image forming apparatus having a monochrome only mode capable of printing a monochrome image in addition to the color mode, in the monochrome only mode. An object of the present invention is to provide an image forming apparatus that eliminates the consumption and deterioration of the color toner cartridge during use.

The above problem is solved by the following means.
(1) A plurality of cartridge mounting portions on which a toner cartridge having a developing portion and an image carrier on which a toner image of a corresponding color is formed by the developing portion is mounted, and is provided so as to be able to run and A transfer body to which the toner image is transferred is pressed against the image carrier of the toner cartridge mounted on the cartridge mounting portion, and the transfer body is supported so as to be able to contact with and separate from the image carrier of each toner cartridge. When the transfer body support means, the operation mode setting means capable of setting the color mode and the monochrome only mode as the operation mode, and the color mode as the operation mode are set, the transfer body is mounted on all cartridge mounting portions. In addition, the contact mode is pressed against each image carrier of all toner cartridges, and the monochrome mode is set as the operation mode. In this case, the transfer body support means is set so that the transfer body is in pressure contact only with the image carrier of the monochrome toner cartridge on which the toner image is formed and is separated from the image carrier of the other toner cartridge. An image forming apparatus comprising: a control unit that controls the image forming apparatus.
(2) In the separation mode of the transfer body, the transfer body is in pressure contact only with the image carrier of the monochrome toner cartridge mounted on the cartridge mounting portion on the most downstream side in the running direction of the transfer body. apparatus.
(3) The operation mode setting means determines whether or not a color image can be formed and whether or not a monochrome image can be formed by using the toner cartridge mounted on the cartridge mounting unit. When the image is possible, the operation mode is set to the color mode. When the color image cannot be formed and the monochrome image can be formed, the operation mode is set to the monochrome only mode. The image forming apparatus described.
(4) The image forming apparatus according to (1), wherein the operation mode setting unit sets a monochrome only mode based on a user's selection.
(5) The image forming apparatus according to item 1 or 2, wherein printing is performed at a higher speed when the transfer body is in the separation mode than in the pressure contact mode.
(6) When the transfer member is in the separation mode, the toner cartridge can be stored in a cartridge mounting portion other than the cartridge mounting portion in which the toner cartridge pressed against the image carrier is mounted. The image forming apparatus described.
(7) In the monochrome only mode, when the monochrome toner cartridge is not attached to the most downstream cartridge attachment portion in the traveling direction of the transfer member, the most downstream of the monochrome toner cartridge attached to another cartridge attachment portion 3. The image forming apparatus according to item 2 above, wherein a message for prompting transfer to the mounting unit is displayed on a display unit of the apparatus or an external apparatus.
(8) The color image forming apparatus according to item 3 above, wherein the operation mode setting means sets the operation mode to the color mode when the cause of making the color image impossible is eliminated.

  According to the invention described in (1) above, in addition to the color mode, a monochrome-only mode capable of printing a monochrome image can be set, and in this monochrome-only mode, the transfer member forms a monochrome toner image. A separation mode is set in which only the image carrier of the monochrome toner cartridge is pressed against the image carrier of the other toner cartridge. For this reason, it is not necessary to rotate the developing device of the color toner cartridge, and it is possible to prevent consumption and deterioration of the color carton cartridge.

  According to the invention described in item (2) above, in the transfer member separation mode, the transfer member is in pressure contact only with the image carrier of the monochrome toner cartridge mounted on the most downstream cartridge mounting portion in the running direction of the transfer member. Therefore, the distance from the primary transfer position of the monochrome toner image formed by the monochrome toner cartridge to the transfer body to the secondary transfer roller for further transferring the image on the transfer body to the paper is shortened, and the image is efficiently formed. be able to.

  According to the invention described in item (3) above, when a color image can be created, the operation mode can be set to the color mode, a color image cannot be created, and a monochrome image can be created. In some cases, the operation mode can be set to the monochrome only mode.

  According to the invention described in item (4), the monochrome only mode can be set based on the user's selection.

  According to the invention described in item (5), monochrome printing at high speed is possible.

  According to the invention described in item (6) above, since no toner cartridge other than the toner cartridge in pressure contact with the image carrier is used, a cartridge mounting portion other than the cartridge mounting portion where the toner cartridge is mounted is replaced with a new toner cartridge. It can be effectively used as a storage for

  According to the invention described in the preceding item (7), in the monochrome only mode, when the monochrome toner cartridge is not mounted on the cartridge mounting portion on the most downstream side in the running direction of the transfer body, it is mounted on the other cartridge mounting portion. A message prompting the user to transfer the monochrome toner cartridge to the most downstream mounting portion is displayed on the display unit of the own device or the external device, so that the user sees the display and sees the currently installed monochrome toner cartridge. Can be transferred to the cartridge mounting portion on the most downstream side, which enables monochrome printing in the separation mode.

  According to the invention described in item (8) above, when the cause of making it impossible to form a color image is resolved, the operation mode is set to the color mode, and thereafter color printing is possible. .

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a central sectional view of a color image forming apparatus according to an embodiment of the present invention, and FIG.

  The color image forming apparatus 1 includes an image forming unit 100, a recording paper transport unit 200, a fixing device 300, and the like. A body cover that can be opened and closed is provided on the front surface of the color image forming apparatus 1, and an operation panel (not shown) is provided on the upper surface of the color image forming apparatus 1.

  The image forming unit 100 includes yellow (Y), magenta (M), and cyan (C) color toner cartridges (hereinafter, toner cartridges are also simply referred to as cartridges) 181 to 183, and a monochrome (K) cartridge 184. And an endless intermediate transfer belt 2, a secondary transfer roller 13, an intermediate transfer belt cleaner 8, and the like.

  Each of the cartridges 181 to 184 includes a photosensitive member 3 as an image carrier, a charging unit 5 that charges the photosensitive member 3, an exposure unit 6 that exposes an image pattern, a developing unit 4 that develops toner, and a transfer residual toner. The photosensitive member cleaner 7 is separated from the photosensitive member 3.

  The intermediate transfer belt 2 is disposed to face the upper side of each cartridge, and is allowed to run counterclockwise on the paper surface by a driving roller 22 as indicated by an arrow a in FIG.

  Further, above each of the cartridges 181 to 184 with the intermediate transfer belt 2 interposed therebetween, a primary transfer counter roller for primarily transferring the toner image on the photoconductor 3 onto the intermediate transfer belt 2 at a position facing the photoconductor 3. 231 to 234 are arranged. Of these primary transfer counter rollers 231 to 234, three primary transfer counter rollers excluding the primary transfer counter roller 234 located at the most downstream position in the running direction of the intermediate transfer belt 2 (the position closest to the secondary transfer roller 13). Reference numerals 231 to 233 can be moved away from or in the approaching direction (vertical direction in FIGS. 1 and 2) with respect to the photoreceptor 3 by ON / OFF control of an intermediate transfer belt separation clutch (not shown).

  When the intermediate transfer belt separating clutch is off, the primary transfer opposing rollers 231 to 233 are moved in the approaching direction (downward) with respect to the respective photosensitive members 3, and as shown in FIG. Reference numeral 2 denotes a state in which all the primary transfer counter rollers 231 to 234 are in pressure contact with the photosensitive members 3 of the cartridges 181 to 184, that is, a pressure contact mode.

  On the other hand, when the intermediate transfer belt separation clutch is turned on, the three primary transfer opposing rollers 231 to 233 move upwardly as shown in FIG. The pressure contact state of the intermediate transfer belt 2 to the three photoconductors 3 excluding the downstream photoconductor 3 is released. In this state, the intermediate transfer belt 2 is brought into pressure contact only with the photoreceptor 3 of the most downstream cartridge 184 only by the most downstream primary transfer counter roller 234, and is in a separated state, that is, a separation mode.

  When the operation mode of the image forming apparatus 1 is the color mode, the intermediate transfer belt 2 is in the pressure contact mode, and the four color toner images formed on the photoreceptor 3 of each cartridge 181 to 184 are transferred to the photoreceptor. 3 is sequentially transferred onto the intermediate transfer belt 2 that is in pressure contact with the intermediate transfer belt 3 in an overlapping state. On the other hand, when the operation mode of the image forming apparatus 1 is the monochrome only mode, the separation mode shown in FIG. 2 is set, and the intermediate transfer belt 2 that runs while being in pressure contact with only the photoreceptor 3 of the most downstream cartridge 184 is A monochrome toner image is primarily transferred. The toner image transferred onto the intermediate transfer belt 2 is transferred onto the recording paper 91 by the secondary transfer roller 13. The intermediate transfer belt cleaner 8 separates the transfer residual toner from the intermediate transfer belt 2.

  The recording paper transporting unit 200 forms an image on the intermediate transfer belt 2, a paper feeding roller 10 that feeds the recording paper 91 from the recording paper storage unit 9, a timing roller 11 that temporarily stops the fed recording paper 91, and the intermediate transfer belt 2. The secondary transfer roller 13 that transfers the toner image onto the recording paper 91, the fixing device 300 that fixes the toner image transferred onto the recording paper 91, and the recording paper 91 after fixing are discharged or conveyed on both sides. The paper discharge roller 15 transports to the path 16, and double-sided path transport rollers 17 a and 17 b that transport the recording paper 91 to the timing roller 11 via the duplex transport path 16 in the case of duplex printing.

  The fixing device 300 includes a heating roller 14a to which a halogen heater 21 is attached, a pressure roller 14b, and a thermistor 20 that detects the temperature of the heating roller 14a. By driving the halogen heater 21, the surface temperature of the heating roller 14a is raised. Further, by rotating the heating roller 14a and the pressure roller 14b, the heat of the surface of the heating roller 14a is transmitted to the pressure roller 14b to heat the pressure roller 14b.

  FIG. 3 shows an electrical configuration of a main part of the image forming apparatus 1.

  3, the image forming apparatus 1 includes a cartridge mounting unit 50 in which a control board 40 to which a CPU 41 is mounted and each of the cartridges 181 to 184 (shown as a representative of the cartridge 181 in FIG. 3) is detachably mounted. (In FIG. 3, the cartridge mounting portion on which the cartridge 181 is mounted is shown as a representative).

  A non-volatile memory medium 60 is provided in each of the cartridges 181 to 184 mounted on the cartridge mounting unit 50. The memory medium 60 stores color codes indicating the toner colors of the cartridges 181 to 184, new product information indicating that the cartridges 181 to 184 are new, and the like.

  The CPU 41 comprehensively controls each part of the image forming apparatus 1 including the movement control of the primary transfer opposing rollers 231 to 234, and also communicates with the memory medium 60 of each cartridge 181 to 184, and the memory. Various determinations and operations are performed based on information read from the medium 60.

  In addition to the CPU 41, a non-volatile memory 42 is mounted on the control board 40 in the image forming apparatus, and various information read from the memory medium 60 of the cartridges 181 to 184 and other information are stored. Has been.

  When the cartridges 181 to 184 are mounted on the cartridge mounting portions 50, the memory media 60 of the cartridges 181 to 184 are connected to the serial communication line of the CPU 41. If serial communication between the CPU 41 and each of the toner cartridges 181 to 184 is established, it is determined that the cartridges 181 to 184 are mounted. If serial communication is not established, it is determined that the cartridges 181 to 184 are not mounted.

  Based on the color code indicating the toner color of the cartridge and the new product information indicating that the cartridge is new, stored in the memory medium 60 of each cartridge 181 to 184, the CPU 41 stores the color of each cartridge in the cartridge mounting unit 50. It is possible to determine whether a cartridge is installed. When the new product information is new, the life information of each cartridge 181 to 184 stored in the nonvolatile memory 42 in the image forming apparatus 1 is reset. If not new, the remaining amount of toner is detected based on the life information of each cartridge 181 to 184 stored in the nonvolatile memory 42 in the image forming apparatus 1.

  The CPU 41 determines whether the image forming apparatus 1 operates as a color mode or monochrome mode as the operation mode of the image forming apparatus 1 based on the communication status between the cartridges 181 to 184 and the information read from the memory medium 60. It has a function to set a monochrome only mode that operates as a dedicated machine.

  As an example of the operation mode setting method, in this embodiment, it is determined whether or not a color image can be formed by using a mounted cartridge, and whether or not a monochrome image can be formed. When the image is impossible and the monochrome image can be formed, the monochrome only mode is set.

  In this embodiment, when at least one of the color cartridges corresponds to at least one of the cartridge not mounted on the cartridge mounting unit 50 or the end of its life (including toner empty), it is impossible to form a color image. If the monochrome cartridge corresponds to at least one of the case where the cartridge is not mounted on the cartridge mounting unit 50 or the end of its lifetime (including toner empty), it is determined that monochrome image formation is impossible.

  If a monochrome cartridge capable of image formation is mounted on at least one of the plurality of cartridge mounting portions 50, it is determined that monochrome image formation is possible.

  Therefore, for example, a user opens a main body cover (not shown) of the image forming apparatus 1 and takes out at least one of the color cartridges, or replaces at least one of the color cartridges with a monochrome cartridge and mounts a plurality of monochrome cartridges. In such a case, as long as the mounted monochrome cartridge does not expire, the monochrome only mode is set and the operation as a monochrome only machine is possible.

  In addition, when the above-described cause that makes it impossible to form a color image is eliminated, it is determined that a color image can be created, and the color mode is set as the operation mode.

  In this embodiment, the user can select the monochrome only mode, and the CPU 41 accepts the monochrome only mode when the user selects it, and sets the monochrome only mode. It has a function. In this case, even if a color image can be formed, the apparatus is operated as a monochrome machine.

  It should be noted that the user can select the monochrome only mode via an operation panel (not shown) or a terminal device such as a personal computer via a communication line.

  In this embodiment, when the color mode is set as the operation mode, color printing is performed by setting the intermediate transfer belt 2 to the pressure contact mode shown in FIG. 1, and when the monochrome only mode is set, 2, monochrome printing is performed in a separation mode in which the intermediate transfer belt 2 is in pressure contact only with the photosensitive member 3 of the cartridge 184 located on the most downstream side in the traveling direction of the intermediate transfer belt 2. In the separation mode, since the intermediate transfer belt 2 is in pressure contact only with the photosensitive member 3 of one cartridge 184, the intermediate transfer belt 2 can be driven at a higher speed than in the pressure contact mode, and high-speed printing can be performed. it can.

  However, when no monochrome cartridge is mounted on the cartridge mounting portion 50 located on the most downstream side in the traveling direction of the intermediate transfer belt 2, monochrome printing cannot be performed in the separation mode, so the monochrome only mode is set. Even in this case, monochrome printing is performed with the intermediate transfer belt 2 in the pressure contact mode shown in FIG.

  As described above, in the monochrome only mode, by performing the monochrome printing with the intermediate transfer belt 2 as the separation mode, the intermediate transfer belt 2 is in pressure contact with only the photosensitive member 3 of the monochrome cartridge 184, and the image carrier of the other color cartridge. Therefore, it is not necessary to rotate the developing device of the color cartridge, and it is possible to prevent the color cartridge from being consumed and deteriorated.

  Further, in the separation mode, the intermediate transfer belt 2 is brought into pressure contact only with the photoreceptor 3 of the most downstream cartridge 184 because the distance from the primary transfer position to the secondary transfer roller 13 by this cartridge is short, and image formation is performed efficiently. Because it can be done.

  However, the position of the cartridge in pressure contact with the intermediate transfer belt 2 in the separation mode is not limited to the most downstream, and may be the most upstream cartridge 181, or between the most upstream cartridge 181 and the most downstream cartridge 184. Intermediate cartridges 182 and 183 may also be used.

  FIG. 4 is a flowchart illustrating an operation mode determination process performed by the image forming apparatus 1. This process is executed by the CPU 41 operating according to a program written in a recording medium such as a ROM (not shown).

  When the main body cover of the image forming apparatus 1 is closed in step S001 (YES in step S001), it is detected in step S002 whether or not the cartridges 181 to 184 are mounted and what color cartridge is mounted. Specifically, serial communication with the nonvolatile memory medium 60 of each cartridge 181 to 184 is performed, and if there is a response from the memory medium 60 to the communication data from the CPU 41, each cartridge 181 to 184 is mounted. The color of the cartridges 181 to 184 mounted is determined by reading the color code indicating the color of the cartridge from the memory medium 60.

  Subsequently, in step S003, new product information is read from the nonvolatile memory medium 60 of each of the cartridges 181 to 184. For a cartridge whose new product information is new, a new product reset operation is performed by initializing the cartridge life information stored in the nonvolatile memory 42 of the image forming apparatus 1. After this new article reset operation, the life information of the mounted cartridge 15 is confirmed, and it is determined that the cartridge that has exceeded the life cannot be printed.

  Next, in step S004, it is determined whether color printing is possible based on the execution results of the cartridge mounting detection step (step S002) and the cartridge life detection step (S003). If at least one of the Y, C, and M color cartridges is not mounted or has been determined to be unable to print due to reaching its end of life, it is determined that color printing is not possible.

  If it is determined that color printing is possible (YES in step S004), it is determined in step S005 whether the monochrome only mode is selected based on the user's operation.

  If the monochrome only mode is selected (YES in step S005), it is determined in step S006 whether or not the monochrome cartridge 184 is mounted on the most downstream cartridge mounting unit 50.

  If the monochrome cartridge 184 is mounted on the most downstream cartridge mounting section 50 (YES in step S006), the monochrome only mode is set as the operation mode even if color printing is possible, and the intermediate transfer belt 2 is further set. Is set to the separation mode, and the image forming apparatus 1 is operated at a high speed as a monochrome machine.

  If the monochrome cartridge 184 is not attached to the most downstream cartridge attachment unit 50 (NO in step S006), in step S008, the intermediate transfer belt 2 is set in the pressure contact mode, and the image forming apparatus 1 is operated as a monochrome-only machine. In step S015, the monochrome cartridge mounted on the operation panel of the image forming apparatus 1 or the display of an external device such as a personal computer connected to the image forming apparatus 1 is transferred to the mounting portion 50 on the most downstream side. Display a prompt message.

  The user can see the display and transfer the currently mounted monochrome toner cartridge to the most downstream cartridge mounting section 50, thereby enabling high-speed monochrome printing in the separation mode of the intermediate transfer belt 2.

  If the monochrome only mode is not selected in step S005 (NO in step S005), the color mode is set as the operation mode in step S009, and the image forming apparatus 1 is operated as a color machine. In this case, the intermediate transfer belt 2 is in the pressure contact mode.

  On the other hand, if it is determined in step S004 that color printing is impossible (NO in step S004), the process proceeds to step S010 to determine whether monochrome printing is possible. This determination is also made based on the execution results of the cartridge mounting detection step (step S002) and the cartridge life detection step (S003).

  If at least one monochrome cartridge whose lifetime has not expired is mounted among the four cartridge mounting sections 50, it is determined that monochrome printing is possible (YES in step S010), and the most downstream cartridge mounting section 50 is determined in step S011. It is determined whether or not the monochrome cartridge 184 is mounted.

  If the monochrome cartridge 184 is mounted on the most downstream cartridge mounting section 50 (YES in step S011), in step S012, the monochrome only mode is set as the operation mode, and the intermediate transfer belt 2 is set to the separation mode, and the image is set. The forming apparatus 1 is operated as a monochrome machine at high speed.

  If the monochrome cartridge 184 is not attached to the most downstream cartridge attachment unit 50 (NO in step S011), in step S013, the intermediate transfer belt 2 is set in the pressure contact mode, and the image forming apparatus 1 is operated as a monochrome-only machine. In step S016, a message is displayed on the operation panel of the image forming apparatus 1 or a display of an external apparatus connected to the image forming apparatus 1 to prompt the user to transfer the mounted monochrome cartridge to the most downstream mounting unit 50. To do.

  The user can see the display and transfer the currently mounted monochrome toner cartridge to the most downstream cartridge mounting unit 50, thereby enabling monochrome high-speed printing in the separation mode.

  When it is determined that monochrome printing is not possible (NO in step S010) in the monochrome printing possible determination (step S010), since neither color nor monochrome printing is possible, the operation panel or image of the image forming apparatus 1 is determined in step S014. An error message is displayed on the display of the external device connected to the forming apparatus 1 to prompt the user to install or replace the cartridge.

  As described above, the color mode or the monochrome only mode is set as the operation mode of the image forming apparatus, the intermediate transfer belt 2 is set to the pressure contact mode or the separation mode, and the image forming apparatus 1 is operated according to those modes.

  Further, when the power of the image forming apparatus 1 is turned on again, or when the main body cover is closed again, there is a possibility that the mounting state of the cartridges 181 to 184 has been changed, so the processing shown in FIG. 4 is performed again. In this case, the color mode is set when the cause of making color printing impossible is solved and the monochrome only mode is not set by the user.

  As can be understood from the above description, when the image forming apparatus 1 is operated with the intermediate transfer belt 2 in the separation mode, the cartridge mounting portion 50 in which the monochrome toner cartridge 184 in contact with the intermediate transfer belt 2 is mounted. Even if the cartridges 181 to 183 are mounted on the mounting portion 50 other than the above, these cartridges are not used.

  For this reason, the cartridge mounting unit 50 other than the cartridge mounting unit 50 in which the monochrome toner cartridge 184 to be used is mounted can be used as a spare cartridge inventory space (cartridge storage). In this case, for the cartridges 181 to 183 that are not used, the photosensitive member 3 and the developing unit 4 are not driven, the charging unit 5 and the exposure unit 6 are not controlled, and the cartridge non-volatile memory 60 is also written. In this case, it is possible to store the stock cartridge as it is, and it is possible to eliminate the necessity of securing the stock space of the spare cartridge outside the image forming apparatus.

1 is a central sectional view of a color image forming apparatus according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a state in which the intermediate transfer belt is set to a separation mode in the image forming apparatus of FIG. 1. FIG. 2 is a block diagram illustrating an electrical configuration of a main part of the image forming apparatus in FIG. 1. 3 is a flowchart illustrating an operation mode determination process performed by the image forming apparatus in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Intermediate transfer belt 3 Photoreceptor 4 Developing part 13 Secondary transfer roller 41 CPU
DESCRIPTION OF SYMBOLS 50 Cartridge mounting part 91 Recording paper 100 Image forming part 181-184 Cartridge 200 Recording paper conveyance part 231-234 Primary transfer counter roller (transfer body support means)

Claims (8)

A plurality of cartridge mounting portions to which a toner cartridge having a developing portion and an image carrier on which a toner image of a corresponding color is formed by the developing portion is mounted;
A transfer body that is provided so as to be able to run and is pressed against the image carrier of a toner cartridge mounted on the cartridge mounting portion while running, and to which the toner image is transferred;
Transfer body support means for supporting the transfer body in an detachable manner with respect to an image carrier of each toner cartridge;
An operation mode setting means capable of setting a color mode and a monochrome only mode as an operation mode;
When the color mode is set as the operation mode, the transfer body is pressed against each image carrier of all toner cartridges mounted in all cartridge mounting portions, and the monochrome mode is set as the operation mode. In this case, the transfer body is supported so that the transfer body is in pressure contact only with the image carrier of the monochrome toner cartridge on which the toner image is formed and separated from the image carrier of other toner cartridges. Control means for controlling the means;
An image forming apparatus comprising:   2. The image forming apparatus according to claim 1, wherein in the separation mode of the transfer body, the transfer body is in pressure contact only with an image carrier of a monochrome toner cartridge mounted on a cartridge mounting portion on the most downstream side in the running direction of the transfer body.   The operation mode setting means determines whether or not a color image can be formed and whether or not a monochrome image can be formed by a toner cartridge mounted on the cartridge mounting unit, and can form a color image. The operation mode is set to the color mode when the color image is, and when the color image cannot be formed and the monochrome image can be formed, the operation mode is set to the monochrome only mode. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the operation mode setting unit sets a monochrome only mode based on a user's selection.   The image forming apparatus according to claim 1, wherein when the transfer body is in the separation mode, printing is performed at a higher speed than in the pressure contact mode.   3. The stock toner cartridge can be stored in a cartridge mounting portion other than the cartridge mounting portion in which a toner cartridge that is in pressure contact with the image carrier is mounted when the transfer member is in the separation mode. Image forming apparatus.   In the monochrome only mode, when the monochrome toner cartridge is not attached to the most downstream cartridge attachment portion in the running direction of the transfer body, the most downstream attachment portion of the monochrome toner cartridge attached to another cartridge attachment portion The image forming apparatus according to claim 2, wherein a message that prompts the user to transfer to is displayed on a display unit of the apparatus or an external apparatus. The color image forming apparatus according to claim 3, wherein the operation mode setting unit sets the operation mode to a color mode when a cause that makes it impossible to form a color image is resolved.

Images