JP6060633B2 - Image forming apparatus and toner supply control method thereof - Google Patents

Description

The present invention relates to an image forming apparatus having a plurality of developing units. More specifically, the present invention relates to an image forming apparatus that forms an image while supplying toner from toner bottles respectively corresponding to a plurality of developing units. The present invention is also directed to a toner supply control method in the image forming apparatus.

  A color image forming apparatus normally forms a color image using yellow, magenta, cyan, and black toners. Therefore, it has four developing units for each color. However, in a color image forming apparatus, not all of these four colors of toner are consumed evenly. For example, some users may have more opportunities to form a monochrome image using only black toner than to form a color image using four color toners. In this case, more black toner is consumed than other color toners.

  For such a user, it is preferable that the capacity of the image forming apparatus that can store the black toner is larger than the capacity that can store other color toners. This is because the troublesomeness that the black toner needs to be replenished frequently is reduced. However, designing and manufacturing a variety of development units having different capacities increases the cost of the image forming apparatus. Further, there is a limit to the size of the developing unit that can be mounted on the image forming apparatus.

  Therefore, for example, Patent Document 1 discloses an image forming apparatus capable of forming an image with a plurality of developing units containing toner of the same color. That is, the image forming apparatus of Patent Document 1 has a development rotary equipped with a plurality of development units, and performs image formation while switching the development unit to be used by the development rotary. In addition, each developing unit can be attached to and detached from the developing rotary, and the developing unit can be replaced with one containing toner of any color. For example, when a large amount of monochrome image is formed only with black toner, the image is formed by replacing all the developing units with those containing black toner. As a result, it is not necessary to replenish toner frequently. The developing units are all the same shape and size, and there is no need to design various developing units.

JP 2002-351190 A

  By the way, the image forming apparatus disclosed in Patent Document 1 has a configuration in which toner is replenished by replacing the developing unit mounted on the developing rotary. However, there is also an image forming apparatus having a developing unit and a toner bottle for supplying toner to the developing unit. In an image forming apparatus having a developing unit and a toner bottle, toner is normally replenished by replacing the toner bottle.

  When the color is changed in such an image forming apparatus, the toner in the developing unit may be different from the toner in the toner bottle corresponding to the developing unit. Specifically, for example, in an image forming apparatus equipped with four toner bottles for each color, all toner bottles are replaced with one containing black toner in order to form a large amount of monochrome images. This is the case. In this case, the toner in the developing unit and the toner in the toner bottle are different while the color toner before the replacement remains in the developing unit.

  Also, for example, when a developing unit that has reached the end of its life is replaced with a reused product of a developing unit that was previously used as a different color. In this case, a toner that has been used before may remain slightly in the development unit of the reuse product. In such cases, the toner in the developing unit is mixed with toners of different colors replenished from the toner bottle to form a mixed color toner, so that there is a possibility that an image with good color cannot be formed. Further, toners having different colors may have different properties such as chargeability and fluidity. This may cause problems such as toner fog or toner spillage in the mixed color toner.

The present invention has been made for the purpose of solving the problems of the prior art described above. That is, the problem is to form a stable quality image by preventing the toner in the toner bottle from being mixed with the toner in the developing unit when the toner in the toner bottle and the toner in the developing unit are different. It is an object of the present invention to provide an image forming apparatus capable of performing the above. A toner replenishment control method in the image forming apparatus is also provided.

In order to solve this problem, an image forming apparatus according to the present invention forms an image bearing member that carries a toner image, and contains toner and applies the toner contained therein to the image bearing member. An image forming apparatus comprising: an image forming unit having a developing unit; and a toner replenishing unit connected to the developing unit and replenishing toner to the connected developing unit, wherein the color of toner contained in the developing unit A first color information output unit that outputs information, a second color information output unit that outputs color information of toner supplied from the toner supply unit to the development unit, and toner supply from the toner supply unit to the development unit are permitted. A replenishment deciding unit that decides whether to perform or restrict, when the color information of the first color information output unit is different from the color information of the second color information output unit, Residual toner amount is the amount of toner being volume is greater than empty less than the lower limit of the proper range predetermined image quality can be obtained, it is determined whether or less replenishment limited predetermined amount of the residual If the toner amount is less than or equal to the replenishment limit amount, toner replenishment is permitted. If the remaining toner amount is greater than the replenishment limit amount, toner replenishment is restricted, and the color information and second color information output unit of the first color information output unit If the color information is the same, the image forming apparatus is characterized in that the toner replenishment is permitted without determining the remaining toner amount. The toner replenishment control method of the present invention is housed in a developing unit in an image forming apparatus that includes an image forming unit having an image carrier and a developing unit, and a toner replenishing unit that replenishes toner to the developing unit. First color information that is toner color information is acquired, second color information that is color information of toner supplied to the developing unit is acquired from the toner supply unit, and the first color information and the second color information are different. When the first determination is executed and the two color information is different in the first determination, the remaining toner amount that is the amount of toner accommodated in the developing unit is obtained as a predetermined image quality. A second determination is made to determine whether the amount is less than a predetermined replenishment limit amount that is less than the lower limit value of the appropriate range and greater than the empty, and if the remaining toner amount is less than the replenishment limit amount, the toner is replenished. Allow and leave Tona If the amount is greater than the replenishment limit amount, toner replenishment is restricted. If both color information is the same in the first determination, toner replenishment control is permitted by permitting toner replenishment without performing the second determination. Is the method.

  In the image forming apparatus of the present invention, when the colors of the toners stored in the developing unit and the toner replenishing unit are different, the development by the toner replenishing unit is performed only when the remaining toner amount in the developing unit is less than the replenishment limit amount. Allow toner replenishment to the unit. The replenishment limit amount is such that even if toner is replenished when the residual toner amount in the developing unit is less than or equal to the replenishment limit amount, an image with good color can be formed by the replenished toner. It is predetermined. Furthermore, even if the supplied toner is mixed with the developing unit having a remaining toner amount equal to or less than the replenishment limit amount, the toner fog or toner spillage does not occur. Therefore, the image forming apparatus of the present invention forms a stable quality image by preventing the toner in the toner bottle from being mixed with the toner in the developing unit when the toner in the toner bottle and the toner in the developing unit are different. can do.

In the image forming apparatus described above, the replenishment determining unit re-determines whether to allow or restrict toner replenishment after restricting toner replenishment because the remaining toner amount is greater than the replenishment limit amount. It is preferable that when the predetermined redetermination event occurs, the remaining toner amount is determined again. By determining the remaining toner amount when a redetermination event occurs, if the developing unit consumes toner and the remaining toner amount at the time of the determination is less than the replenishment limit amount, the toner replenishing unit This is because toner can be supplied.

  The image forming apparatus described above further includes an image density detecting unit that detects an image density of a toner image formed by the developing unit, and the replenishment determining unit forms a test toner image by the image forming unit. It is preferable that the density of the test toner image thus detected is detected by an image density detection unit, and the remaining toner amount is detected by the detected value. The supply limit amount is an extremely small amount of toner. Therefore, for example, a sensor that detects the amount of toner installed in the developing unit or the like may not accurately detect whether or not the amount of toner in the developing unit is less than or equal to the replenishment limit amount. Therefore, it is possible to accurately determine whether or not the amount of toner in the developing unit is less than or equal to the replenishment limit amount by forming a test toner image on the developing unit and detecting the image density.

  Further, in the image forming apparatus described above, the developing unit has an approximate toner amount output unit that outputs an approximate toner amount indicating an approximate value of the remaining toner amount, and the replenishment determining unit is more than the approximate toner amount output unit. If the acquired approximate toner amount exceeds a predetermined approximate toner amount threshold, toner supply is limited without determining the remaining toner amount, and the approximate toner amount is less than or equal to the approximate toner amount threshold. In this case, it is preferable that the remaining toner amount is determined. It is not preferable to frequently develop the test toner image by the developing unit. This is because the test toner image is not a toner image related to image formation. Therefore, the test toner image is developed when the remaining toner amount is equal to or less than the approximate toner amount threshold that is reduced to some extent. It is preferable to determine the remaining toner amount from the detected value of the test toner image.

  Further, in the image forming apparatus described above, the replenishment determining unit, when the consumed toner amount, which is the integrated amount of toner consumed by the developing unit by the development, does not satisfy a predetermined consumed toner amount threshold, Without determining the toner amount, the replenishment of toner may be limited, and the remaining toner amount may be determined when the consumed toner amount exceeds the consumed toner amount threshold. This is because the remaining toner amount in the developing unit can be obtained from the toner consumption amount.

  In the image forming apparatus described above, the image forming unit includes a plurality of combinations of the image forming unit, the toner replenishing unit, the first color information output unit, and the second color information output unit. A color determining unit that determines whether to permit or restrict the formation of the color image, and the color determining unit forms a predetermined color image by combining the color information of the plurality of first color information output units; When the remaining toner amounts of the developing units of the plurality of image forming units are equal to or greater than a predetermined color limit amount threshold value, the formation of a color image is permitted. The combination of the color information of the first color information output unit is not a combination that can form a predetermined color image, or any one of the remaining toner amounts of the developing units of the plurality of image forming units. If it is less than the predetermined color restriction amount threshold is preferably intended to limit the formation of color images. According to the present invention, a toner having a color different from the toner in the developing unit can be appropriately supplied by the toner supply unit. Therefore, for example, the developing unit after the replenishment is actually accommodated toner of a color different from the previous one. In such a case, it is preferable to prohibit the formation of a color image because an appropriate color image cannot be formed.

  In the image forming apparatus described above, the image forming unit includes a plurality of combinations of the image forming unit, the toner replenishing unit, the first color information output unit, and the second color information output unit. An intermediate transfer member that receives the transfer of the toner image from the image carrier, a cleaning member that contacts the intermediate transfer member and removes toner on the surface thereof, and a protective toner developed by any of the developing units of the plurality of image forming units A reverse rotation control unit that rotates the intermediate transfer member in a direction opposite to the rotation direction during normal image formation while holding the image on the intermediate transfer member. If there is a different color developing unit in which the color information of the first color information output unit is different from the color information of the second color information output unit, the protection toner image is Current color development unit It is preferable that the. The protective toner image is a toner image that is subsequently discarded. In addition, when the toner in the toner replenishing unit is a different color toner from the developing unit, the user often thinks that the toner in the developing unit is unnecessary. Therefore, it is preferable to develop the protection toner image to be discarded with unnecessary toner.

  In the image forming apparatus described above, the image forming unit includes a plurality of combinations of the image forming unit, the toner replenishing unit, the first color information output unit, and the second color information output unit. Each development unit includes a development determination unit that determines whether development is permitted or restricted, and a mode switching unit that switches between a high image quality mode and a low image quality mode, and the development determination unit includes a plurality of images. In the developing unit of the forming unit, there is a mixed color developing unit in which the first toner supply related to the permission is performed after the toner supply is permitted because the remaining toner amount is equal to or less than the replenishment limit amount. If present, the development by the mixed color developing unit is restricted if the high image quality mode is selected in the mode switching unit, and allowed if the low image quality mode is selected in the mode switching unit. Prefer Arbitrariness. At least the toner of the color before replenishment remains in the mixed color developing unit. Therefore, in a high image quality mode that requires the formation of an extremely high quality image, there is a possibility that an image with a level of image quality required by the user cannot be formed.

  Further, in the image forming apparatus described above, the development determining unit is a low image quality that is an integrated amount of toner consumed by development in the low image quality mode after the mixed color development unit is restricted in development in the high image quality mode. When the consumption amount is equal to or higher than a predetermined low image quality consumption threshold value, it is preferable that the development by the mixed color developing unit is permitted even when the high image quality mode is selected by the mode switching unit. This is because the mixed color developing unit after consuming a certain amount of toner can form an image of the level required in the high image quality mode.

According to the present invention, when the toner in the toner bottle and the toner in the developing unit are different, it is possible to form a stable quality image by preventing the toner in the toner bottle from being mixed with the toner in the developing unit. An image forming apparatus is provided. A toner replenishment control method executed in the image forming apparatus is also provided.

1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment. FIG. 2 is a diagram illustrating an outline of a control configuration of an image forming apparatus according to the present embodiment. FIG. 7 is a diagram for explaining a method for detecting the amount of toner in a developing unit by a density sensor. It is a figure which shows the relationship between the A / D value of the test toner image detected by the density sensor, and the density of the test toner image. 6 is a flowchart illustrating a procedure of toner supply control according to the present exemplary embodiment. It is a flowchart which shows the procedure of the color restriction control of this form. It is a flowchart which shows the procedure from prohibition of high picture quality mode of this form to permission.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the accompanying drawings. In this embodiment, the present invention is embodied in an electrophotographic printer.

  FIG. 1 shows a schematic configuration of an image forming apparatus 1 of the present embodiment. The image forming apparatus 1 is a so-called tandem color printer having an intermediate transfer belt 30. The intermediate transfer belt 30 is an endless belt member having conductivity, and both ends in the figure are supported by rollers 31 and 32. At the time of image formation, the roller 31 on the right side in FIG. 1 is driven to rotate counterclockwise. As a result, the intermediate transfer belt 30 and the left roller 32 in FIG. 1 are driven to rotate.

  A secondary transfer roller 40 is provided on the outer peripheral surface of the portion of the intermediate transfer belt 30 supported by the right roller 31 in FIG. The secondary transfer roller 40 and the outer peripheral surface of the intermediate transfer belt 30 are in contact with each other, and a secondary transfer region is formed by the contact transfer nip N1.

  Also, a belt cleaner 41 is provided on the outer peripheral surface of the portion of the intermediate transfer belt 30 supported by the left roller 32 in FIG. The belt cleaner 41 is in pressure contact with the outer peripheral surface of the intermediate transfer belt 30, and a collection area 42 for collecting the transfer residual toner is formed by the contacting portion.

  In the lower part of the intermediate transfer belt 30 in FIG. 1, the image forming units 10Y, 10M, 10C for yellow (Y), magenta (M), cyan (C), and black (K) are sequentially arranged from left to right. 10K is arranged. The image forming units 10Y, 10M, 10C, and 10K are all for transferring the toner images of the respective colors onto the intermediate transfer belt 30. The image forming units 10Y, 10M, 10C, and 10K all have the same configuration. For this reason, in FIG. 1, the image forming unit 10 </ b> Y is represented by a reference numeral.

  That is, the image forming units 10Y, 10M, 10C, and 10K include a photosensitive member 11 that is a cylindrical electrostatic latent image carrier, and a charger 12, a developing unit 70, and a photosensitive member cleaner 16 disposed around the photosensitive member. have. A primary transfer roller 15 is disposed at a position facing the photoconductor 11 with the intermediate transfer belt 30 therebetween. Further, an exposure device 13 is disposed below the image forming units 10Y, 10M, 10C, and 10K for each color in FIG. The charger 12 is for uniformly charging the surface of the photoconductor 11. The exposure device 13 is for irradiating the surface of the photoconductor 11 with laser light based on image data to form an electrostatic latent image. The developing unit 70 is for applying toner to the surface of the photoreceptor 11 by the developing roller 71.

  Above the intermediate transfer belt 30 in FIG. 1, hoppers 80Y, 80M, 80C and 80K are arranged. The hoppers 80Y, 80M, 80C, and 80K are each provided with a toner bottle 90 that contains toner of the corresponding color. Each hopper 80 is connected to the developing unit 70 of the image forming unit 10 of the corresponding color. The hopper 80 is for appropriately supplying toner contained in the toner bottle 90 to the corresponding developing unit 70.

  Further, the toner bottle 90 has a CSIC (Customer Specific Integrated Circuit) 91. The CSIC 91 is a non-volatile memory that stores color information and the like of toner stored in the toner bottle 90. For example, currently, “yellow” is stored as color information in the CSIC 91 of the toner bottle 90 mounted on the hopper 80Y.

  Further, the developing unit 70 has a toner level sensor 72 and a CSIC 73. The toner level sensor 72 is for detecting the amount of toner stored in the developing unit 70. The toner level sensor 72 is, for example, a reflection type having a light projecting unit and a light receiving unit. The replenishment of toner to the developing unit 70 by the hopper 80 is performed based on the toner amount in each developing unit 70 detected by the toner level sensor 72.

  That is, when the amount of toner detected by the toner level sensor 72 is less than or equal to the lower limit value of the appropriate range, the toner is replenished. As a result, the toner amount in the developing unit 70 is kept within an appropriate range. The appropriate range of the toner amount in the developing unit 70 is a range of toner amount that can develop an appropriate toner image in the developing unit 70. However, even if the amount of toner in the developing unit 70 falls below the lower limit value of the appropriate range, a certain margin is provided in the appropriate range so that the image quality does not deteriorate immediately. Note that the detection of the toner amount by the toner level sensor 72 is performed, for example, at a cycle of 10 ms.

  The CSIC 73 is a non-volatile memory that stores color information of toner stored in the developing unit 70. For example, currently, “yellow” is stored as color information in the CSIC 73 of the developing unit 70 of the image forming unit 10Y. In addition to the color information, the CSIC 73 also stores the dot counter value that the developing unit 70 has developed so far, the toner amount detected by the toner level sensor 72, and the like.

  Note that the lower limit value of the toner amount detectable range by the toner level sensor 72 of the present embodiment is not much lower than the lower limit value of the appropriate toner amount range in the developing unit 70. That is, it is impossible to detect a state where the toner amount in the developing unit 70 is remarkably smaller than the lower limit value of the appropriate range or a completely empty state. Further, the toner level sensor 72 of this embodiment detects a local toner amount in the developing unit 70. For this reason, the toner amount detected by the toner level sensor 72 is a rough toner amount in the developing unit 70. However, depending on the type, number, and location of sensors used as the toner level sensor 72, it is possible to accurately detect the toner amount in the developing unit 70 from within an appropriate range or its lower limit value to complete empty. .

  A density sensor 20 for detecting the image density of the transferred toner image is provided at a position downstream of the image forming unit 10K in the rotation direction of the intermediate transfer belt 30 and upstream of the transfer nip N1. . The density sensor 20 uses the outer peripheral surface of the intermediate transfer belt 30 as a detection position. The density sensor 20 detects, for example, the amount of reflected light having an irradiation unit and a light receiving unit. The density sensor 20 can detect how much toner is on the detection position on the intermediate transfer belt 30. In this embodiment, the measurement value of the density sensor 20 is converted into an 8-bit A / D value by A / D conversion and processed as density data of 256 gradations from 0 to 255.

  In FIG. 1, the charger 12 is a roller charging type having a roller shape, but the present invention is not limited to this. A corona discharge charging charger, a blade charging member, a brush charging member, or the like may be used. Further, although the photosensitive member cleaner 16 is a plate and has one end portion in contact with the outer peripheral surface of the photosensitive member 11, the present invention is not limited to this. Other cleaning members, for example, a fixed brush, a rotating brush, a roller, or a combination of a plurality of them can be used. Alternatively, if a cleaner-less system in which the untransferred toner on the photoconductor 11 is collected by the developing unit 70, the photoconductor cleaner 16 may be omitted.

  A detachable paper feed cassette 51 is mounted at the lower part of the image forming apparatus 1. A conveyance path 50 is provided above the right side in FIG. Then, the sheets P stored in the sheet feeding cassette 51 by stacking are sent out one by one from the uppermost one to the conveying path 50 by the sheet feeding roller 52.

  A pair of registration rollers 53, a transfer nip N 1, a fixing device 60, and a paper discharge roller 54 are arranged in this order on the conveyance path 50 of the paper P sent out by the paper feed roller 52. A paper discharge unit 55 is provided on the upper surface of the image forming apparatus 1 further downstream of the transport path 50. The registration roller 53 is for adjusting the timing of feeding the paper P to the transfer nip N1. The fixing device 60 is for fixing the toner image transferred onto the paper P by heating and pressurizing the paper P at the fixing nip N2.

  An example of a normal image forming operation by the image forming apparatus 1 of this embodiment will be briefly described. The following description is an example of an image forming operation when a color image is formed using four color toners.

  During normal image formation, the intermediate transfer belt 30 and the photoreceptors 11 of the respective colors are rotated at a predetermined peripheral speed in the directions indicated by arrows in FIG. First, the outer peripheral surface of the photoconductor 11 is charged almost uniformly by the charger 12. Next, light corresponding to the image data is projected onto the outer peripheral surface of the charged photoconductor 11 by the exposure device 13 to form an electrostatic latent image. Subsequently, the electrostatic latent image is developed with toner supplied by the rotation of the developing roller 71 of the developing unit 70, and a toner image is formed on the photoreceptor 11.

  The toner images of the respective colors formed on the photosensitive member 11 are transferred (primary transfer) onto the intermediate transfer belt 30 by the primary transfer roller 15. That is, yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 30 in this order. The transfer residual toner that is not transferred to the intermediate transfer belt 30 and remains on the photoconductor 11 even after passing the primary transfer roller 15 is scraped off by the photoconductor cleaner 16 and removed from the photoconductor 11. . The superimposed four color toner images are conveyed to the transfer nip N1 by the intermediate transfer belt 30.

  On the other hand, the paper P stored in the paper feed cassette 51 is pulled out from the uppermost one by one to the transport path 50 by the paper feed roller 52. The drawn paper P is conveyed along the conveyance path 50, and reaches the transfer nip N1 by the registration roller 53 in synchronization with the toner image placed on the intermediate transfer belt 30. Then, the superimposed four color toner images are transferred (secondary transfer) onto the paper P in the transfer nip N1.

  The paper P on which the toner image has been transferred is further conveyed downstream of the conveyance path 50. That is, the paper P is discharged to the paper discharge unit 55 by the paper discharge roller 54 after the toner image is fixed by the fixing device 60. The toner image remaining on the intermediate transfer belt 30 even after passing through the transfer nip N1 is scraped off by the belt cleaner 41 in the recovery area 42. As a result, the intermediate transfer belt 30 is removed.

  Next, FIG. 2 shows an outline of the control configuration of the image forming apparatus 1 of the present embodiment. The image forming apparatus 1 includes a controller unit 2 and an engine control unit 3. The controller unit 2 is for controlling the entire image forming apparatus 1. For example, a print job is generated in the image forming apparatus 1 by receiving an image forming command input by a user through a personal computer. The print job is managed by the controller unit 2. Further, the controller unit 2 performs processing for converting the data of the managed print job into data for forming an image in the image forming apparatus 1. The data after the conversion process is transmitted to the engine control unit 3.

  The engine control unit 3 includes a CPU 4, a nonvolatile memory attached to the main body 5, various loads 6 of the image forming apparatus 1, and a nonvolatile memory 7 attached to the unit. The nonvolatile memory 5 attached to the main body is, for example, an EEPROM. The nonvolatile memory 5 stores various programs for executing image formation, threshold values used in the programs, and the like.

  The various loads 6 are drive sources for the operation units such as the developing roller 71, the paper feeding roller 52, and the registration roller 53 of the developing unit 70 in the image forming apparatus 1. The non-volatile memory 7 attached to the unit is a memory attached to consumables in the image forming apparatus 1. The nonvolatile memory 7 is, for example, the CSIC 73 of the developing unit 70, the CSIC 91 of the toner bottle 90, or the like.

  The CPU 4 is for controlling reading and writing of the nonvolatile memories 5 and 7 and driving and stopping of the various loads 6. In the image forming apparatus 1, the CPU 4 performs image formation of the image data received from the controller unit 2 based on information stored in the nonvolatile memories 5 and 7. For this reason, various information such as a dot counter value is exchanged between the controller unit 2 and the CPU 4. Also, execution of toner supply control, which will be described later, is performed.

  Further, the image forming apparatus 1 of the present embodiment can form an image while switching between the high image quality mode and the low image quality mode. For example, the resolution is set to 1200 dpi in the high image quality mode, and the resolution is set to 600 dpi in the low image quality mode. These image quality modes are managed by the controller unit 2. The CPU 4 controls the image forming apparatus 1 according to the image quality mode instructed from the controller unit 2 to form an image.

  In such an image forming apparatus 1, the toner in the developing unit 70 is consumed by performing image formation. In general, the developing unit 70 that has consumed toner is replenished with toner from the toner bottle 90 in order to keep the amount of toner contained therein within an appropriate range.

  By the way, the toner in the developing unit 70 and the toner in the toner bottle 90 corresponding thereto are not always the same. For example, some users may want to use the image forming apparatus 1 purchased for color as a monochrome-only machine that prints a large amount of black-and-white images only. In this case, it is also possible to form an image using only the image forming unit 10K without using the image forming units 10Y, 10M, and 10C. However, when image formation is performed using only the image forming unit 10K, it is necessary to frequently replace the toner bottle 90 at the position of the hopper 80K.

  Therefore, it may be preferable to cause the image forming units 10Y, 10M, and 10C to perform image formation using black toner. This is because the replacement frequency of the toner bottle 90 can be reduced to a quarter. For this purpose, the toner bottle 90 mounted on the hoppers 80Y, 80M, and 80C is replaced with one containing black toner. On the other hand, replacement of the developing unit 70 of the image forming unit 10 requires a certain amount of cost. Therefore, when the image forming apparatus 1 is a monochrome dedicated machine at low cost, it is preferable to use the developing units 70 of the image forming units 10Y, 10M, and 10C as they are.

  Therefore, even after all the toner bottles 90 of the hoppers 80Y, 80M, and 80C are replaced with those containing black toner, the yellow, magenta, and cyan toners are respectively present in the developing units 70 of the image forming units 10Y, 10M, and 10C. May remain. In other words, the toner in the developing unit 70 of the image forming units 10Y, 10M, and 10C is in a different color from the toner in the corresponding toner bottle 90.

  Further, for example, the developing unit 70 of the image forming unit 10 that has been exhausted and has reached the end of its life may be replaced with a reusable one that is not new. This is because the development unit 70 can be replaced at low cost. However, the reused developing unit 70 for replacement may be a unit that has been used before to develop a color different from the color in the image forming unit 10 after replacement. Further, there may be a case where toner that has been used before remains in the reused developing unit 70. Even in such a case, the toner in the developing unit 70 after replacement and the toner in the toner bottle 90 corresponding to the toner are in different states.

  As described above, the developing unit 70 and the toner bottle 90 of the present embodiment each have the CSIC 73 and the CSIC 91 in which the color information of the toner to be stored is stored. For this reason, it is possible to detect whether the toner in the developing unit 70 is different from the toner in the toner bottle 90 corresponding to the toner by checking the color information of the CSIC 73 and the CSIC 91.

  In the image forming apparatus 1 of the present embodiment, when the color information of the developing unit 70 and the toner bottle 90 is different and the amount of toner in the developing unit 70 is large, the toner bottle 90 by the hopper 80 is transferred from the toner bottle 90 to the developing unit 70. The toner supply is limited. This is because the toner in the developing unit 70 may be mixed with toners of different colors supplied from the toner bottle 90 to become mixed color toners, so that an image with good color may not be formed. In addition, toners may have different properties such as chargeability and fluidity due to different colors. Therefore, when the toner in the developing unit 70 is mixed with toner of different properties supplied from the toner bottle 90, problems such as toner fog and toner spillage may occur.

  On the other hand, even when the color information of the developing unit 70 and the toner bottle 90 is different, if the amount of toner in the developing unit 70 is extremely small, the toner supply from the toner bottle 90 to the developing unit 70 by the hopper 80 is performed. I do. This is because when the amount of toner in the developing unit 70 is extremely small, there is no problem that an image formed thereafter can be easily observed visually even if toner color mixing occurs in the developing unit 70. Further, in the developing unit 70, the ratio of the toner amount replenished from the toner bottle 90 to the total amount of toner becomes almost all. In other words, since the properties of the toner in the developing unit 70 are almost uniform, toner fog and toner spillage are suppressed.

  Here, when the color information of the developing unit 70 and the toner bottle 90 is different, the threshold value of the toner amount in the developing unit 70 that is a boundary of whether or not to replenish the toner from the toner bottle 90 to the developing unit 70 is set. Suppose the supply limit amount. The replenishment limit amount is a value determined by conducting an experiment in advance on the above-described problems caused by toner replenishment. That is, in the developing unit 70, even when toners of different colors replenished from the toner bottle 90 are mixed with toner less than the replenishment limit amount, an image with good color is formed by the replenished color toners. it can. Further, even when toner is supplied to the developing unit 70 having a toner amount less than the supply limit amount, problems such as toner fog toner spillage do not occur.

  In this embodiment, the replenishment limit amount determined in this way is a toner amount that is extremely smaller than the lower limit value of the appropriate range of toner amount in the developing unit 70 and slightly larger than empty. Therefore, the replenishment limit amount is smaller than the lower limit value of the toner amount detectable range by the toner level sensor 72. Therefore, the accurate determination of whether or not the toner amount in the developing unit 70 is less than or equal to the replenishment limit amount cannot be performed using the toner level sensor 72 in the image forming apparatus 1 of the present embodiment.

  Therefore, the developing unit 70 develops the test toner image and the toner image is detected by the density sensor 20 to determine whether or not the toner amount in the developing unit 70 is less than the replenishment limit amount. The smaller the amount of toner stored in the developing unit 70, the smaller the amount of toner attached to the toner image developed by the developing unit 70. Therefore, the toner amount in the developing unit 70 can be detected by detecting the density of the toner image developed by the developing unit 70. A method of detecting the toner amount in the developing unit 70 by the density sensor 20 will be described with reference to FIG.

  FIG. 3 is a view of the right end portion of the intermediate transfer belt 30 shown in FIG. 1 as viewed from below in FIG. FIG. 3 shows a normal toner image S and test toner images TY, YM, and TC carried on the intermediate transfer belt 30. The normal toner image S is a toner image for image formation related to a print job, which is then transferred to the paper P at the transfer nip N1.

  Test toner images TY, YM, and TC are toner images of yellow, magenta, and cyan toners formed by the developing units 70 of the image forming units 10Y, 10M, and 10C, respectively. In the following, the test toner images TY, YM, and TC are collectively referred to as a test toner image T. The test toner image T is a test toner image for detecting the amount of toner in the developing unit 70 based on its density. Accordingly, the test toner image T is thereafter removed from the intermediate transfer belt 30 by the belt cleaner 41 without being transferred to the paper P in the transfer nip N1.

  Both the normal toner image S and the test toner image T are toner images that are developed on the photoreceptor 11 by the developing unit 70 and then transferred onto the intermediate transfer belt 30. The test toner image T is a single-layer toner image developed by one of the four developing units 70 of each color, which is a detection target of the toner amount. Further, the test toner image T of the present embodiment is a so-called solid image.

  As shown in FIG. 3, the test toner image T is formed outside the normal image area where the normal toner image S is carried. Specifically, in this embodiment, the intermediate transfer belt 30 is carried between the regions where the normal toner image S is carried in the rotation direction. A density sensor 20 is disposed in the traveling direction of the test toner image T. Therefore, the test toner image T passes through the detection position of the density sensor 20 after the state shown in FIG. Further, during the passage, the image density is detected by the density sensor 20.

  FIG. 4 shows the relationship between the A / D value of the test toner image T detected by the density sensor 20 and the density of the test toner image T. In FIG. 4, the vertical axis indicates the A / D value (8 bits) of the test toner image T detected by the density sensor 20. The horizontal axis indicates the density of the test toner image T by 256 gradations with 0/255 being the maximum density. As shown in FIG. 4, the higher the gradation of the test toner image T, the higher the A / D value that is the detected value. That is, it can be seen that the A / D value increases as the toner amount in the developing unit 70 is smaller and the toner adhesion amount on the test toner image T is smaller.

  Further, the A / D value indicated by X and the gradation indicated by Y in FIG. 4 are values corresponding to the toner replenishment limit amount in the developing unit 70, respectively. That is, when the toner amount in the developing unit 70 is less than or equal to the replenishment limit amount, the test toner image T to be developed has a small amount of toner adhesion, so that the gradation of the test toner image T becomes Y or higher. The A / D value detected from the test toner image T whose gradation is Y or higher is X or higher as shown in FIG. Note that the A / D value X shown in FIG. Therefore, by determining whether the A / D value detected from the test toner image T by the density sensor 20 is equal to or greater than the replenishment limit threshold X, it is determined whether the toner amount in the developing unit 70 is equal to or less than the replenishment limit amount. be able to.

  Next, the toner supply control of this embodiment will be described with reference to the flowchart of FIG. The toner replenishment control is a control for determining whether or not to permit replenishment of toner in the toner bottle 90 to the developing unit 70 by the hopper 80. The toner replenishment control is executed when the power of the image forming apparatus 1 is turned on or when a cover for exchanging the toner bottle 90 or the developing unit 70 is opened or closed. The toner replenishment control is executed for each hopper 80 of each color.

  In the toner replenishment control, first, toner replenishment is prohibited for any hopper 80 (S101). Next, the color information stored in each of the CSIC 73 of the developing unit 70 and the CSIC 91 of the toner bottle 90 is acquired (S102), and it is determined whether the color information is different (S103). If the color information of the CSIC 73 and the CSIC 91 is the same (S103: NO), the toner supply by the hopper 80 is "permitted" (S109), so that the toner amount in the developing unit 70 is below the lower limit value of the appropriate range. In this case, the hopper 80 supplies toner.

  On the other hand, when the color information of the CSIC 73 and the CSIC 91 is different (S103: YES), it is determined whether or not the toner amount in the developing unit 70 is detected by the density sensor 20 (S104). Specifically, the toner amount in the developing unit 70 is detected by the density sensor 20 when the toner amount in the developing unit 70 is equal to or less than a predetermined residual toner amount threshold value. In this embodiment, the remaining toner amount threshold is set to a toner amount that is smaller than the lower limit value of the appropriate range of toner amount in the developing unit 70 and larger than the lower limit value of the detectable range of the toner level sensor 72. Then, the toner level sensor 72 detects a state in which the toner amount in the developing unit 70 is equal to or less than the remaining toner amount threshold.

  In order to detect the toner amount in the developing unit 70 by the density sensor 20, it is necessary to develop the test toner image T. However, it is not preferable to frequently develop the test toner image T. The test toner image T is not a toner image related to image formation transferred to the paper P. For this reason, frequent development of the test toner image T results in wasteful consumption of toner. When the toner amount in the developing unit 70 is equal to or less than the remaining toner amount threshold, the amount is not so large. Therefore, the test toner image T is developed when the toner amount in the developing unit 70 becomes equal to or less than the remaining toner amount threshold. As a result, the amount of toner used for the test toner image T can be reduced.

  If it is determined that the toner amount in the developing unit 70 is to be detected by the density sensor 20 because the toner amount in the developing unit 70 is equal to or less than the remaining toner amount threshold value (S104: YES), the developing unit 70 Thus, the test toner image T is developed (S105). Further, the test toner image T is detected by the density sensor 20 (S106).

  If it is determined that the A / D value of the detected test toner image T is greater than or equal to the replenishment restriction threshold X (S107: YES), toner replenishment is set to “permitted” (S109). At this time, because the A / D value is equal to or greater than the replenishment limit threshold X, the toner amount in the developing unit 70 is equal to or less than the replenishment limit amount.

  Accordingly, toner is supplied from the toner bottle 90 to the developing unit 70 by the hopper 80. At the time of replenishment, the amount of toner in the developing unit 70 is extremely small because it is less than the replenishment limit amount. Therefore, an image with good color can be formed with the color toner replenished by the toner bottle 90 thereafter. Further, toner fog and toner spillage can be suppressed.

  Before the replenishment is performed, different color information is stored in the CSIC 73 of the developing unit 70 and the CSIC 91 of the toner bottle 90, respectively. Therefore, when the CPU 4 replenishes toner when the color information of the CSIC 73 and the CSIC 91 is different, the color information of the CSIC 73 of the developing unit 70 is changed to the same color information as the color information of the CSIC 91 of the toner bottle 90 along with the replenishment. Perform rewrite processing.

  On the other hand, when it is determined that the A / D value of the detected test toner image T is smaller than the supply limit threshold X (S107: NO), the toner amount in the developing unit 70 is again detected by the density sensor 20. It is determined whether or not to perform (S108). The determination in step S108 is performed by a method different from the toner amount detection by the toner level sensor 72 in step S104. In step S108, based on the toner consumption amount of the developing unit 70 after the determination in step S107, it is determined whether or not the toner amount in the developing unit 70 is to be detected by the density sensor 20. For example, after the determination in step S107, every time 2.25g or more of toner in the developing unit 70 is consumed (S108: YES), steps S105 to S107 may be performed again.

  Specifically, the toner consumption in the developing unit 70 can be calculated from the dot counter value. The amount of toner consumed by the developing unit 70 when developing the toner image has a certain proportional relationship with the dot counter value. For example, in the case of the developing unit 70 of this embodiment, about 2.25 mg of toner is consumed for a dot counter value of 1. Therefore, in step S108 of this embodiment, the dot counter values after the determination in step S107 are integrated. When the integrated value of the dot counter value is 1000 counts (S108: YES), steps S105 to S107 are performed again.

  Similarly, the determination in step S104 can be made based on the toner consumption. As described above, the toner consumption amount in the developing unit 70 can be calculated from the dot counter value. That is, whether or not the toner amount in the developing unit 70 is less than or equal to the replenishment limit amount based on the amount of toner accommodated when the toner bottle 90 is attached and the integrated value of the dot counter value that has been integrated since the toner bottle 90 is attached. Can be determined. For example, if the toner bottle 90 is a 4k product (corresponding to a filling amount of 135 g) and the replenishment limit amount is 6.75 g, the integrated value of the dot counter value that starts integration when the toner bottle 90 is attached is 57000 counts. When the above is reached, the toner amount in the developing unit 70 may be detected by the density sensor 20.

  Further, the determination in step S104 may be performed by comprehensively detecting the detection value of the toner level sensor 72 and the dot counter value. For example, the remaining toner amount threshold value may be set to a toner amount smaller than the lower limit value of the detectable range of the toner level sensor 72. In this case, after detecting the lower limit value of the detectable range by the toner level sensor 72, it is detected from the toner consumption amount based on the dot counter value that the toner amount in the developing unit 70 has become less than the remaining toner amount threshold value. Can do.

  Furthermore, in the image forming apparatus 1, it is preferable to perform color restriction control so that a color image can be formed only when all the developing units 70 that contain yellow, magenta, cyan, and black toners are available. . In the color restriction control, as shown in the flowchart of FIG. 6, first, when the power of the image forming apparatus 1 is turned on, or when the cover for exchanging the toner bottle 90 or the developing unit 70 is opened or closed. In step S201, color image formation is set to “permitted”.

Next, color information is read from the CSIC 73 of all the developing units 70 (S202). The combination of color information of all the developing units 70 is yellow,
It is determined whether the color is magenta, cyan, or black (S203). That is, it is determined whether or not the combination of the developing units 70 is a combination that can form a color image.

  When the combination of the color information of the developing units 70 is yellow, magenta, cyan, and black (step 203: YES), there is an amount of toner capable of forming an image in all the developing units 70. It is determined whether or not there is (S204).

  The determination of “present” of the toner in step S204 can be performed by the toner level sensor 72, for example. That is, when the toner amount in the developing unit 70 detected by the toner level sensor 72 is larger than the above-described remaining toner amount threshold value in step S104 of FIG. Further, for example, it is possible to determine whether or not the toner amount in the developing unit 70 is larger than the remaining toner amount threshold value based on the dot counter value. If it is determined that the toner in all the developing units 70 is “present” (S204: YES), the color image formation is allowed as it is. Note that the threshold value of “present” in the determination in step S204 may not be the same as the remaining toner amount threshold value.

  On the other hand, when the combination of the developing units 70 is not yellow, magenta, cyan, or black (S203: NO), the formation of the color image is “prohibited”. This is because it is impossible to develop all of the toners of the respective colors for forming a color image. Even when the combination of the developing units 70 is yellow, magenta, cyan, and black (S203: YES), even when the toner in at least one of the developing units 70 is not determined to be “present” ( S204: NO), the color image formation is “prohibited”. This is because there is too little toner or an empty developing unit 70 cannot form an appropriate color image.

  As described with reference to the flowchart of FIG. 5 described above, the image forming apparatus 1 according to the present embodiment has, for example, the case where the toner bottle 90 containing black toner is mounted at the position of the hopper 80Y. An image can be formed while suppressing toner mixing. However, in this case, black toner may be supplied from the toner bottle 90 into the developing unit 70. That is, the image forming apparatus 1 does not include the developing unit 70 that develops yellow toner. Therefore, when such a color image cannot be appropriately formed, it is preferable to prohibit the formation of the color image.

  In the image forming apparatus 1 of the present embodiment, foreign matter such as a piece of paper discharged from the paper P may be caught in the collection area 42 where the belt cleaner 41 is pressed against the intermediate transfer belt 30. If this foreign matter bite occurs, the belt cleaner 41 may not be able to properly collect the toner on the intermediate transfer belt 30. The toner remaining on the intermediate transfer belt 30 due to insufficient collection of the belt cleaner 41 may appear as noise in an image formed thereafter.

  Therefore, when foreign matter is caught in the collection area 42, reverse rotation control for rotating the intermediate transfer belt 30 in the direction opposite to that during normal image formation may be performed in order to remove the foreign matter. In the reverse rotation control, a protective toner image is arranged in advance on a portion of the outer peripheral surface of the intermediate transfer belt 30 in the collection area 42 when rotating in the direction opposite to the normal direction. This is to prevent damage to the surface of the intermediate transfer belt 30 and to reduce the load on the belt cleaner 41. The protective toner image is removed by the belt cleaner 41 by the rotation of the intermediate transfer belt 30 that rotates during normal image formation after the reverse rotation control. The protective toner image is a toner image developed prior to the reverse rotation of the intermediate transfer belt 30 in the reverse rotation control.

  When there is a developing unit 70 that stores toner of different colors with respect to the toner bottle 90, the protective toner image is preferably developed by the developing unit 70. There is a high possibility that a user who has installed a toner bottle 90 containing different color toners in the developing unit 70 already thinks that the toner remaining in the developing unit 70 is unnecessary. Therefore, when there is a developing unit 70 that stores toners of different colors with respect to the toner bottle 90, the protective toner image that is not transferred onto the paper P is preferably developed by the developing unit 70. . It should be noted that the developing unit 70 for developing the protective toner image must naturally have an amount of toner that can develop the protective toner image.

  Further, the image forming apparatus 1 of the present embodiment can form an image while switching between the high image quality mode and the low image quality mode. Here, when the toner information is supplied from the toner bottle 90 to the developing unit 70 in a state where the color information of the CSIC 73 of the developing unit 70 and the CSIC 91 of the toner bottle 90 are different (after S107 in FIG. 5: YES, Toner replenishment), the toner in the developing unit 70 is at least a mixed color toner. As described above, the color mixture toner referred to here is a fine color mixture toner that does not significantly affect the image quality. For example, even if a slightly mixed color toner is used in the low image quality mode, it is difficult to visually confirm the degree of the mixed color.

  However, it is preferable not to form an image in the high image quality mode using the developing unit 70 that accommodates such a slightly mixed color toner until a certain amount of the slightly mixed color toner is consumed. Users who select the high image quality mode are considered to be requesting extremely high quality images. However, depending on the slightly mixed color toner in which even a slight color mixture occurs, for example, the color mixture may be slightly visible in the halftone part, and there is a possibility that an extremely high quality image as required may not be formed. is there.

  FIG. 7 is a flowchart for explaining the image quality mode switching condition when there is a developing unit 70 that contains the slightly mixed color toner by supplying the toner. First, when the developing unit 70 containing the slightly mixed color toner is generated due to the replenishment of toner (toner replenishment after YES in S107 in FIG. 5), the developing unit 70 performs the high-quality mode. Development is prohibited (S301).

  Next, every time an image is formed using the developing unit 70 of slightly mixed color toner, the number of sheets P is counted (S302, S303). Of course, the image formation using the developing unit 70 of the slightly mixed color toner is performed in the low image quality mode. Further, the count number of sheets P is compared with a predetermined low image quality sheet number threshold (S304). The low image quality sheet number threshold is a value set to such an extent that the image formation in the high image quality mode is not affected by an experiment using the developing unit 70 containing the slightly mixed color toner. For example, the low image quality threshold value can be set to 100 sheets.

  When the counted number is equal to or greater than the low image quality number threshold (S304: YES), the selection of the high image quality mode is set to “permitted”. That is, thereafter, the image formation in the high image quality mode can be performed using the developing unit 70 of the slightly mixed color toner. At this time, the developing unit 70 of the slightly mixed color toner may be further supplied with toner from the toner bottle 90 in addition to the supply of toner when the slightly mixed color toner is reached. As a result, the image forming apparatus 1 can stably form a high-quality image in the high-quality mode.

  In step S303, the amount of toner consumed in step S302 may be integrated, and the integrated value may be compared with a toner consumption threshold corresponding to the low image quality number threshold in step S304. The toner consumption in this case can be detected by the toner level sensor 72 of the developing unit 70 that contains the slightly mixed color toner. A dot counter value can also be used.

As described in detail above, the image forming apparatus 1 of the present invention includes the developing unit 70 and the toner bottle 90 for supplying toner to the developing unit 70. Further, the developing unit 70 and the toner bottle 90 have a CSIC 73 and a CSIC 91 that store color information, respectively. In the toner replenishment control, first, the color information of the CSIC 73 and the color information of the CSIC 91 are compared. If the color information is different, the test toner image T is developed by the developing unit 70. Then, the test toner image T is detected by the density sensor 20, and it is determined whether or not the detected A / D value is greater than or equal to the supply limit threshold value X. If it is equal to or greater than the replenishment limit threshold X, it is determined that the toner amount in the developing unit 70 is less than or equal to the replenishment limit amount. That is, the toner supply from the toner bottle 90 to the developing unit 70 by the hopper 80 is permitted. As a result, when the toner in the toner bottle 90 and the toner in the developing unit 70 are different, mixing of the toner in the toner bottle 90 with the toner in the developing unit 70 can be prevented, and an image with stable quality can be formed. A forming apparatus 1 is provided. A toner replenishment control method executed in the image forming apparatus 1 is also provided.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, when the color information of the CSIC 73 and the CSIC 91 is different, the determination as to whether or not the hopper 80 is to replenish toner does not necessarily have to be made by detecting the test toner image T by the density sensor 20. When a sensor capable of accurately detecting the toner amount of the supply limit amount is used as the toner level sensor 72, the detection can be performed based on the detected value. In this case, it may be determined, for example, every 10 ms whether or not the toner amount in the developing unit 70 detected by the toner level sensor 72 is less than or equal to the replenishment limit amount.

  For example, in the above embodiment, the detection position of the density sensor 20 is described as being on the intermediate transfer belt 30, but the present invention is not limited to this. The detection position of the density sensor 20 may be on the downstream side of the developing unit 70, and the detection position can be on the photoconductor 11. The present invention is not limited to a color printer, and can be applied to, for example, an image forming apparatus that transmits and receives a print job via a public line.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 2 ... Controller part 3 ... Engine control part 10Y, 10M, 10C, 10K ... Image forming part 11 ... Photoconductor 70 ... Developing unit 73 ... CSIC
80Y, 80M, 80C, 80K ... Hopper 90 ... Toner bottle 91 ... CSIC

Claims (10)

An image forming unit comprising: an image carrier that carries a toner image; and a developing unit that contains toner and applies the toner contained therein to the image carrier to form a toner image;
In an image forming apparatus comprising a toner replenishing unit connected to the developing unit and replenishing toner to the connected developing unit,
A first color information output unit for outputting color information of toner contained in the developing unit;
A second color information output unit for outputting color information of toner replenished to the developing unit from the toner replenishing unit;
A replenishment determining unit that determines whether to permit or restrict toner replenishment from the toner replenishing unit to the developing unit;
The replenishment determining unit
When the color information of the first color information output unit is different from the color information of the second color information output unit,
Whether the residual toner amount, which is the amount of toner accommodated in the developing unit, is less than a predetermined replenishment limit amount that is less than a lower limit value of an appropriate range in which a predetermined image quality can be obtained and more than empty. Judgment,
If the remaining toner amount is less than the replenishment limit amount, allow toner replenishment,
If the amount of remaining toner is greater than the supply limit, supply of toner is limited.
When the color information of the first color information output unit and the color information of the second color information output unit are the same, replenishment of toner is permitted without determining the remaining toner amount. An image forming apparatus. The image forming apparatus according to claim 1,
The replenishment determining unit
After the toner supply is limited due to the remaining toner amount being greater than the supply limit amount, the remaining toner amount is again determined when a predetermined redetermination event occurs that re-determines whether to allow or limit toner supply. An image forming apparatus for determining a toner amount. The image forming apparatus according to claim 1, wherein:
An image density detector for detecting an image density of a toner image formed by the developing unit;
A test toner image is formed by the image forming unit,
An image forming apparatus, wherein the density of the formed test toner image is detected by the image density detection unit, and the remaining toner amount is detected by the detected value. The image forming apparatus according to claim 1, wherein:
The developing unit has an approximate toner amount output unit for outputting an approximate toner amount indicating an approximate value of the remaining toner amount;
The replenishment determining unit
If the approximate toner amount acquired from the approximate toner amount output unit exceeds a predetermined approximate toner amount threshold, the toner supply is limited without determining the remaining toner amount, and the approximate toner amount is determined. An image forming apparatus for determining the amount of remaining toner when the toner becomes less than or equal to an approximate toner amount threshold. The image forming apparatus according to claim 1, wherein:
The replenishment determining unit
If the consumed toner amount, which is the cumulative amount of toner consumed by the developing unit by the developing unit, is less than a predetermined consumed toner amount threshold value, the replenishment of toner is limited without determining the remaining toner amount. ,
An image forming apparatus for determining a residual toner amount when a consumed toner amount is equal to or greater than a consumed toner amount threshold value. The image forming apparatus according to any one of claims 1 to 5,
A plurality of combinations of the image forming unit, the toner replenishing unit, the first color information output unit, and the second color information output unit;
A color determining unit that determines whether to allow or restrict the formation of a color image by the plurality of image forming units;
The color determining unit
A combination of color information of the plurality of first color information output units is a combination capable of forming a predetermined color image; and
When all of the residual toner amounts of the developing units of the plurality of image forming units are equal to or greater than a predetermined color limit amount threshold, the formation of a color image is permitted,
The combination of color information of the plurality of first color information output units is not a combination that can form a predetermined color image, or
If any one of the remaining toner amounts of the developing units of the plurality of image forming units is less than a predetermined color limit amount threshold, the formation of a color image is limited. Image forming apparatus. The image forming apparatus according to any one of claims 1 to 5,
A plurality of combinations of the image forming unit, the toner replenishing unit, the first color information output unit, and the second color information output unit;
An intermediate transfer member that receives a transfer of a toner image from the image carrier of the plurality of image forming units;
A cleaning member that contacts the intermediate transfer member and removes toner on the surface;
While carrying the protective toner image developed by any one of the developing units of the plurality of image forming units on the intermediate transfer member, the intermediate transfer member is opposite to the rotation direction during normal image formation. A reverse rotation control unit that rotates in the direction,
The reverse rotation control unit
When there is a different color developing unit in which the color information of the first color information output unit is different from the color information of the second color information output unit among the developing units of the plurality of image forming units Is
An image forming apparatus, wherein the protective toner image is developed by the different color developing unit. The image forming apparatus according to any one of claims 1 to 5,
A plurality of combinations of the image forming unit, the toner replenishing unit, the first color information output unit, and the second color information output unit;
A development determining unit that determines whether development is permitted or restricted for each of the development units of the plurality of image forming units;
A mode switching unit for switching between a high image quality mode and a low image quality mode;
The development determining unit
In the developing units of the plurality of image forming units, after the toner replenishment is permitted because the remaining toner amount is equal to or less than the replenishment limit amount, the first toner replenishment for the permission is performed. If there is a mixed color development unit,
Development by the mixed color developing unit,
Limit if the high-quality mode is selected in the mode switching unit,
An image forming apparatus, wherein the mode switching unit permits the low image quality mode if it is selected. The image forming apparatus according to claim 8,
The development determining unit
A low image quality consumption amount, which is an integrated amount of toner consumed by development in the low image quality mode after the mixed color development unit is restricted in development in the high image quality mode, is a predetermined low image quality consumption threshold value. If this is the case,
2. An image forming apparatus according to claim 1, wherein even when the high quality mode is selected by the mode switching unit, development by the mixed color developing unit is permitted. An image forming unit comprising: an image carrier that carries a toner image; and a developing unit that contains toner and applies the toner contained therein to the image carrier to form a toner image;
A toner replenishment control method in an image forming apparatus, comprising: a toner replenishing unit connected to the developing unit and replenishing toner to the connected developing unit;
Obtaining first color information which is color information of toner contained in the developing unit;
Obtaining second color information which is color information of toner replenished to the developing unit from the toner replenishing unit;
Performing a first determination to determine whether the first color information is different from the second color information;
If the first color information and the second color information are different in the first determination,
Whether the residual toner amount, which is the amount of toner accommodated in the developing unit, is less than a predetermined replenishment limit amount that is less than a lower limit value of an appropriate range in which a predetermined image quality can be obtained and more than empty. Perform a second determination to determine,
If the remaining toner amount is less than the replenishment limit amount, allow toner replenishment,
If the amount of remaining toner is greater than the supply limit, supply of toner is limited.
When the first color information and the second color information are the same in the first determination,
A toner replenishment control method in an image forming apparatus, wherein toner replenishment is permitted without performing the second determination.

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