JP2018045014A - Image formation device, program and image formation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique that suppresses occurrence of development defects in an image formation device allowing a cartridge storing toner to be mounted/detached.SOLUTION: A printer 100 comprises a development cartridge 4 that has a toner storage part 70 storing toner, and forms a toner image on a photoreceptor 51 via a development roller 61, using the toner to be supplied. The printer 100 is configured to judge whether the mounted development cartridge 4 is a cartridge having a characteristic of the toner unknown; and when it is judged that the characteristic of the toner is unknown, set a velocity ratio serving as a ratio of a rotation velocity of the development roller 61 to a rotation velocity of the photoreceptor 51 to a low velocity ratio. The low velocity ratio is a velocity ratio smaller than a specified ratio serving as a velocity ratio to be set when it is judged that the mounted development cartridge is not the cartridge having the characteristic of the toner unknown. Then, the printer 100 is configured to form the toner image on the basis of the set velocity ratio.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus, a program, and an image forming method for forming an image by electrophotography.

  Conventionally, in an image forming apparatus that forms an image by electrophotography, it is known that as the number of rotations of the developing roller increases, mechanical stress is applied to the toner, and the charge amount of the toner becomes unstable. When the charge amount of the toner becomes unstable, development problems such as toner leakage from the developing device are likely to occur.

  As a document disclosing control according to the number of rotations of the developing roller, for example, there is Patent Document 1. In Patent Document 1, an image forming apparatus to which a developing cartridge can be attached and detached, a counter that counts the number of rotations of the developing roller is provided, and the toner deteriorates when the number of rotations of the developing roller reaches a predetermined number of times. A configuration for notifying a decrease in image quality is disclosed.

JP 2003-295595 A

  However, the conventional technique described above has the following problems. In other words, cartridges with unknown toner characteristics, such as old cartridges whose usage history is unknown or cartridges whose individual identification information in the memory cannot be read, may be mounted. When such a cartridge is mounted, it cannot be determined whether or not the number of rotations of the developing roller has reached the number of rotations causing a development failure. Therefore, there is a possibility that development problems such as toner leakage cannot be suitably suppressed.

  The present invention has been made to solve the above-described problems of the prior art. That is, an object of the present invention is to provide an image forming apparatus in which a cartridge for storing toner can be attached and detached, and a technique for suppressing the occurrence of development problems.

  An image forming apparatus for solving this problem has a photosensitive member, a developing roller, and a storage portion for storing toner, and is supplied from the storage portion onto the photosensitive member through the developing roller. In the image forming apparatus that includes a forming unit that forms a toner image using the toner that is formed, and at least the storage unit is formed of a cartridge, and a control unit, the control unit is mounted When the determination process determines whether the cartridge is a cartridge whose toner characteristics are unknown, and when the determination process determines that the cartridge is an unknown cartridge, the rotation speed of the photoconductor The speed ratio that is the ratio of the rotation speed of the developing roller is the speed ratio that is set when it is determined in the determination process that the cartridge is not a cartridge with unknown characteristics. A setting process for setting a low speed ratio, which is a speed ratio smaller than a constant ratio, and a forming process for forming a toner image on the forming unit based on the speed ratio set in the setting process. It is a feature.

  The image forming apparatus disclosed in this specification determines whether or not the mounted cartridge is a cartridge with unknown toner characteristics, and if it is determined that the cartridge has unknown toner characteristics, A speed ratio that is a ratio of the rotation speed of the developing roller to the rotation speed is set to a low speed ratio. The low speed ratio is a speed ratio smaller than a specified ratio that is a speed ratio set when it is determined that the cartridge is not a cartridge with unknown toner characteristics. Examples of cartridges whose toner characteristics are unknown include old cartridges whose use history is unknown and cartridges whose toner initial filling amount and toner type are unknown.

  When a cartridge with unknown toner characteristics is mounted, the number of rotations of the developing roller up to a predetermined number of rotations, which is a guideline for developing problems, becomes uncertain. Therefore, in the image forming apparatus disclosed in this specification, when the rotational speed up to a predetermined rotational speed is uncertain, the speed ratio is reduced and the relative rotational speed of the developing roller relative to the rotational speed of the photosensitive member is decreased. To do. Thereby, it can be expected that the occurrence of development defects can be suppressed as compared with the case where the speed ratio is not reduced.

  An image forming method for realizing the functions of the image forming apparatus, a computer program, and a computer-readable storage medium storing the computer program are also novel and useful.

  According to the present invention, it is an image forming apparatus in which a cartridge for storing toner can be attached and detached, and a technology for suppressing the occurrence of development problems is realized.

1 is a cross-sectional view illustrating an internal configuration of a printer according to an embodiment. FIG. 2 is a schematic diagram illustrating a configuration of a developing cartridge. FIG. 2 is a block diagram illustrating an electrical configuration of a printer. 6 is a flowchart illustrating a procedure of speed ratio determination processing executed by a printer in which a developing cartridge including a read-only memory is mounted. 6 is a flowchart illustrating a procedure of a printing process executed by a printer in which a developing cartridge including a read-only memory is mounted. It is a flowchart which shows the procedure of a development bias setting process. It is a flowchart which shows the procedure of the speed ratio determination process performed with the printer which mounts a developing cartridge provided with a writable memory. 6 is a flowchart illustrating a procedure of a printing process executed by a printer in which a developing cartridge including a writable memory is mounted.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an image forming apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a printer that forms an image by electrophotography.

  As shown in FIG. 1, the printer 100 according to this embodiment forms a toner image by electrophotography, transfers the toner image to the sheet S, and transports the sheet S through the process unit 5. A belt 7 and a fixing device 8 for fixing unfixed toner on the sheet S are provided. The process unit 5 is an example of a forming unit. Further, the printer 100 includes a paper feed tray 91 on which the sheet S before toner image transfer is placed, and a paper discharge tray 92 on which the sheet S after image formation is placed.

  Further, as shown by a one-dot chain line in FIG. 1, the printer 100 is provided with a conveyance path 11 that is a path of a substantially S-shaped sheet S surrounded by a wall member (not shown). The printer 100 includes a paper feed roller 21 for conveying the sheet S along the conveyance path 11, a registration roller pair 22, and a paper discharge roller pair 23. That is, the printer 100 uses the sheet feeding roller 21, the registration roller pair 22, the transport belt 7, the sheet discharge roller pair 23, and the like to feed one sheet S stored in the sheet feeding tray 91 to the sheet feeding tray 91. The paper is taken out from the paper, transported along the transport path 11, and discharged to the paper discharge tray 92.

  The printer 100 is a device capable of forming a color image. For this purpose, the process unit 5 is provided with a configuration for forming toner images of respective colors. Specifically, as shown in FIG. 1, the process unit 5 includes a black process unit 50K, a yellow process unit 50Y, a magenta process unit 50M, and a cyan process unit 50C. They are arranged at regular intervals along the direction of travel. Note that the arrangement order of the process parts of each color is not limited to the example shown in FIG.

  As shown in FIG. 1, the black process unit 50K includes a drum-shaped photoconductor 51, a charging device 52, a developing device 54, and a transfer device 55 arranged around the photoconductor 51. ing. The other color process units 50C, 50M, and 50Y have the same configuration as the black process unit 50K except for the toner color. Further, the process unit 5 includes an exposure device 53 as a configuration common to the process units 50C, 50M, 50Y, and 50K for the respective colors.

  The charging device 52 charges the surface of the photoconductor 51. The exposure device 53 exposes the surface of the charged photoreceptor 51 based on the image data. Thereby, an electrostatic latent image is formed on the photosensitive member 51. The developing device 54 develops the electrostatic latent image on the photoreceptor 51 with toner. As a result, a toner image is formed on the photoreceptor 51. The transfer device 55 transfers the toner image on the photoreceptor 51 to the sheet S or the conveyance belt 7. The photosensitive member 51 is opposed to the transfer device 55 with the conveyance belt 7 interposed therebetween.

  When printing a color image on the sheet S, the printer 100 causes each color process unit 50 </ b> C, 50 </ b> M, 50 </ b> Y, 50 </ b> K to form a toner image of each color on each photoconductor 51. In addition, the printer 100 takes out the sheets S placed on the paper feed tray 91 one by one and conveys the sheets S onto the conveyance belt 7. Then, the printer 100 sequentially transfers the toner images formed by the process units 50C, 50M, 50Y, and 50K for the respective colors on the sheet S. Thereafter, the printer 100 conveys the sheet S to which the toner image has been transferred to the fixing device 8, thermally fixes the toner image to the sheet S, and discharges the fixed sheet S to the paper discharge tray 92. When a monochrome image is printed, the printer 100 forms a toner image only on the black process unit 50K.

  Further, as shown in FIG. 1, the printer 100 includes a mark sensor 25 that reads a mark formed on the conveyance belt 7. The mark sensor 25 has a light emitting unit and a light receiving unit (not shown), and the printer 100 uses the mark sensor 25 to adjust the image density. Specifically, the printer 100 forms marks, which are toner images for density acquisition, on the conveyor belt 7 using the process units 50C, 50M, 50Y, and 50K for the respective colors. Then, the printer 100 acquires the density of the mark by causing the light emitting portion of the mark sensor 25 to emit light toward the mark and detecting the amount of light received by the light receiving portion. Then, the printer 100 adjusts various settings for image formation so that the difference between the density of the read mark and the expected density becomes small.

  Next, the developing device 54 of the printer 100 will be described in detail. As shown in FIG. 2, the developing device 54 of the printer 100 is a developing cartridge 4 that includes a toner container and is detachable from the printer 100. That is, the printer 100 has a configuration in which the developing cartridge 4 including the toner storage unit 70 is detachable. The developing cartridge 4 has a developing unit 60 and a toner storage unit 70, both of which are connected via a supply port 69. In this embodiment, a nonmagnetic one-component toner is accommodated in the toner accommodating portion 70 as a developer. The toner storage unit 70 is an example of a storage unit, and the developing cartridge 4 is an example of a cartridge.

  As shown in FIG. 2, the developing unit 60 includes a developing roller 61, a toner supply roller 62, and a regulating member 63. The developing roller 61 carries toner and conveys the carried toner toward the photoreceptor 51. The toner supply roller 62 supplies toner to the developing roller 61 and scrapes off the toner on the developing roller 61. The regulating member 63 regulates the thickness of the toner on the developing roller 61 and charges the toner.

  The toner storage unit 70 is provided with an agitator 71 as a member for stirring the toner. The agitator 71 is rotationally driven in conjunction with the developing roller 61 to stir the toner in the toner storage unit 70. A part of the agitated toner is discharged toward the developing unit 60 through the supply port 69.

  The toner discharged from the supply port 69 to the developing unit 60 is supplied to the developing roller 61 by the rotation of the toner supply roller 62, and at this time, the toner is frictionally charged between the toner supplying roller 62 and the developing roller 61. The toner supplied onto the developing roller 61 enters between the regulating member 63 and the developing roller 61 as the developing roller 61 rotates, and is thinned while being frictionally charged. Then, at a position facing the photoconductor 51, a part of the toner moves onto the photoconductor 51 and develops the electrostatic latent image formed on the photoconductor 51.

  As shown in FIG. 1, the printer 100 has a common motor 57 for rotationally driving the developing rollers 61 of the mounted developing cartridge 4. That is, the printer 100 rotationally drives the developing rollers 61 of all colors by the motor 57 at the same angular velocity.

  Further, the developing cartridge 4 of the printer 100 has a memory 73 attached on the outer wall surface of the toner storage unit 70. The printer 100 has a memory communication unit 74 (see FIG. 3) for each color for communicating with the memory 73 of the mounted developing cartridge 4. The communication method between the memory 73 and the memory communication unit 74 may be wireless communication, or may be wired communication using a terminal that comes in contact with attachment. The memory 73 is an example of a cartridge memory.

  The type of developing cartridge 4 to be used is determined for each model of the printer 100. The memory 73 is a read-only memory or a writable nonvolatile memory, and differs depending on the type of the developing cartridge 4. That is, the type of memory provided in the developing cartridge 4 differs depending on the model of the printer 100. Hereinafter, only when it is necessary to distinguish, the printer 100 using the developing cartridge 4 having the read-only memory 73 is the printer 100A, and the printer 100 using the developing cartridge 4 having the writable nonvolatile memory 73 is the printer. 100B.

  When the developing cartridge 4 is shipped, at least the serial number of the developing cartridge 4 is stored in the memory 73. The contents stored in the memory 73 of the developing cartridge 4 used in the printer 100A are not rewritten by the printer 100A, and only the contents stored at the time of shipment are stored.

  On the other hand, the printer 100B, which is a writable nonvolatile memory in the memory 73, can rewrite the storage contents of the memory 73 of the mounted developing cartridge 4. For example, the printer 100 </ b> B can store information indicating the degree of use of the developing cartridge 4 in the memory 73. The information indicating the usage level of the developing cartridge 4 corresponds to, for example, the cumulative number of printed sheets, the cumulative rotational speed of the developing roller 61, or a value corresponding to these.

  Next, the electrical configuration of the printer 100 will be described. As shown in FIG. 3, the printer 100 of this embodiment includes a controller 30 having a CPU 31, a ROM 32, a RAM 33, and an NVRAM (nonvolatile RAM) 34. Note that the controller 30 in FIG. 3 is a general term that summarizes hardware used for controlling the printer 100 such as the CPU 31, and does not necessarily represent a single piece of hardware that actually exists in the printer 100.

  The ROM 32 stores firmware, which is a control program for controlling the printer 100, various settings, initial values, and the like. The RAM 33 is used as a work area from which various control programs are read or as a storage area for temporarily storing image data. The CPU 31 controls each component of the printer 100 while storing the processing result in the RAM 33 or the NVRAM 34 in accordance with a control program read from the ROM 32 and signals sent from various sensors. The CPU 31 is an example of a control unit. The controller 30 may be a control unit.

  The printer 100 includes a process unit 5 that forms an image by an electrophotographic method, a mark sensor 25, a network interface (IF) 37, a USB interface 38, an operation panel 40, a motor 57, and a motor 58. These are controlled by the CPU 31. The process unit 5 includes process units 50C, 50M, 50Y, and 50K for each color, and further includes memory communication units 74C, 74M, 74Y, and 74K for each process unit of each color.

  As described above, the motor 57 is a motor that rotationally drives the developing roller 61 of each color. The motor 58 is a motor that rotationally drives each roller that conveys the sheet S, a belt roller that moves the conveyance belt 7, each color photoconductor 51, a fixing roller in the fixing device 8, and the like. That is, the controller 30 of the printer 100 controls the rotation speed of the developing roller 61 of each color and the rotation speed of the photoconductor 51 of each color by controlling the motor 57 and the motor 58.

  The network IF 37 is hardware for communicating with a device connected via a network using a LAN cable or the like. The USBIF 38 is hardware for communicating with a device connected via a USB cable or the like. The operation panel 40 is hardware that is responsible for displaying a notification to the user and receiving an instruction input by the user. The operation panel 40 includes, for example, a liquid crystal display and a button group including a start key, a stop key, a numeric keypad, and the like.

  Next, the rotation speed of the developing roller 61 when an image is formed by the printer 100 will be described. The developing cartridge 4 is detachable from the main body of the printer 100, and a new one is not always mounted. If the usage level of the developing cartridge 4 exceeds a predetermined threshold value, the characteristics of the toner stored in the developing cartridge 4 may be changed from the initial state.

  Specifically, there is a possibility that the charging performance of the toner is deteriorated and a charged state equivalent to the initial state cannot be obtained. The low-charged toner has a weak force that adheres to the developing roller 61. For this reason, toner leakage or the like at positions other than the position facing the photoconductor 51 is likely to occur, which may cause the inside of the apparatus or the printed matter to become dirty. The degree of toner leakage tends to increase as the rotation speed of the developing roller 61 increases.

  Further, the printer 100 may not always be able to properly access the memory 73 with respect to the mounted developing cartridge 4. For this reason, the printer 100 may not be able to acquire information indicating the toner characteristics of the mounted developing cartridge 4. If the printer 100 cannot acquire information indicating the toner characteristics of the mounted developing cartridge 4, the remaining usage until the threshold value is reached becomes inaccurate. Therefore, when the toner characteristics of the mounted developing cartridge 4 are unknown, the printer 100 does not know when the threshold value is reached, so the rotation speed of the developing roller 61 is reduced from the beginning.

  Even if the information indicating the toner characteristics of the mounted developing cartridge 4 can be acquired, if the usage level of the developing cartridge 4 exceeds a predetermined threshold value, it is already stored in the developing cartridge 4. The toner characteristics may have changed from the initial state. When the usage level of the developing cartridge 4 exceeds a predetermined threshold, the printer 100 sets the rotation speed of the developing roller 61 to a lower speed setting than when the developing cartridge 61 does not exceed the threshold. This suppresses toner leakage.

  Next, a procedure for printing by determining the rotation speed of the developing roller 61 in the printer 100 will be described. First, processing executed by the printer 100A will be described with reference to the flowcharts of FIGS. FIG. 4 is a flowchart of speed ratio determination processing executed by the printer 100A, and FIG. 5 is a flowchart of printing processing executed by the printer 100A.

  The speed ratio determining process shown in FIG. 4 is executed by the CPU 31 when the replacement condition, which is a condition that the developing cartridge 4 may be replaced, is satisfied in the printer 100A. The replacement conditions include, for example, detecting that the cover of the main body of the printer 100 that is opened and closed when the developing cartridge 4 is replaced and turning on the power. The printer 100A executes this speed ratio determination process for each color developing cartridge 4 after satisfying the replacement condition.

  When the printer 100A starts executing the speed ratio determination process, the printer 100A first reads information stored in the memory 73 of the developing cartridge 4 of the color to be processed via the memory communication units 74C, 74M, 74Y, and 74K (S101). ). Specifically, the printer 100A accesses the memory 73 and reads the stored serial number. The serial number is an example of individual identification information, and S101 is an example of identification information acquisition processing.

  Then, the printer 100A determines whether or not information has been properly read from the memory 73 (S102). For example, when the memory 73 is damaged or when the developing cartridge 4 that does not have the memory 73 is mounted, the printer 100A cannot appropriately read information from the memory 73. If it is determined that the data has been read properly (S102: YES), the printer 100A determines whether the read serial number matches the serial number stored in the NVRAM 34 (S103). S102 is an example of determination processing. S103 is an example of a determination process and an identification information determination process.

  The printer 100A stores the serial number of the mounted developing cartridge 4 in the NVRAM 34, as will be described later, in order to determine whether or not the mounted developing cartridge 4 has been replaced. That is, the printer 100A compares the current serial number read from the memory 73 of the developing cartridge 4 with the previous serial number stored in the NVRAM 34, and determines that it has not been replaced if they match. As will be described later, the printer 100A also stores information indicating the degree of use after the development cartridge 4 is mounted in the NVRAM 34. The NVRAM 34 is an example of a storage unit.

  That is, when the printer 100A determines that the read serial number matches the serial number stored in the NVRAM 34 (S103: YES), the speed ratio determination process is terminated. If the serial number of the mounted developing cartridge 4 matches the previous serial number stored in the NVRAM 34, the developing cartridge 4 has not been replaced. Therefore, the printer 100A applies the previously set speed ratio as it is.

  On the other hand, when it is determined that the read serial number does not match the serial number stored in the NVRAM 34 (S103: NO), the developing cartridge 4 has been replaced. Therefore, the printer 100A determines whether or not the mounted developing cartridge 4 is new (S104). S104 is an example of a new article determination process.

  Since the memory 73 of the developing cartridge 4 attached to the printer 100A is read-only, new product information and information indicating the degree of use are not stored. For this reason, the printer 100A has a mechanical new article detection configuration for determining whether or not the mounted developing cartridge 4 is new. As a configuration of mechanical new article detection, for example, there are a configuration having a toothless gear that rotates only at the time of the first drive, and a configuration having a convex portion that is deformed by the mounting operation. For example, the missing tooth gear meshes with the drive gear of the printer 100A when it is new, receives a rotational driving force, and does not receive the rotational driving force by the missing tooth portion after being rotated by a predetermined angle. The printer 100A can determine whether or not the mounted developing cartridge 4 is new by detecting the rotational position of the missing gear at the time of mounting.

  If it is determined that the mounted developing cartridge 4 is new (S104: YES), the printer 100A sets the speed ratio to the high speed ratio and stores the speed ratio in the NVRAM 34 (S106). The speed ratio is the ratio of the rotation speed of the developing roller 61 to the rotation speed of the photoconductor 51. Note that the printer 100A of this embodiment does not change the rotation speed of the photoconductor 51, but changes the rotation speed of the developing roller 61 to switch the speed ratio. It is presumed that the toner contained in the new developing cartridge 4 has good characteristics. Therefore, it is not necessary to slow down the rotation speed of the developing roller 61. Further, by increasing the rotation speed of the developing roller 61, the toner is smoothly supplied to the photoconductor 51, and the image quality can be improved.

  The printer 100A has three types of speed ratios, a high speed ratio, a medium speed ratio, and a low speed ratio, which are selected in order from the largest value. The high speed ratio is a speed ratio used when it is determined that the toner characteristics are good. The peripheral speed of the developing roller 61 at the high speed ratio is substantially equal to the peripheral speed of the photoconductor 51. At the medium speed ratio and the low speed ratio, the peripheral speed of the developing roller 61 is slower than the peripheral speed of the photoconductor 51. The high speed ratio is an example of the specified ratio, and the medium speed ratio and the low speed ratio are examples of the low speed ratio. The medium speed ratio is an example of a second low speed ratio, and the low speed ratio is an example of a first low speed ratio.

  Further, the printer 100A overwrites and stores the serial number read from the memory 73 in the NVRAM 34 (S107). S107 is an example of a storage process. In addition, the printer 100A resets a usage counter stored in the NVRAM 34 (S108). The usage counter is a counter for storing information indicating the usage level of the developing cartridge 4. For example, the printer 100A counts up the usage counter each time printing is performed on one sheet. Then, the printer 100A ends the speed ratio determination process.

  On the other hand, when it is determined that the mounted developing cartridge 4 is not new (S104: NO), the old product has been replaced, and the degree of use of the developing cartridge 4 is unknown to the printer 100A. However, since the serial number can be acquired, the developer cartridge 4 can read out the serial number. As a result, the characteristics of the contained toner conform to the predetermined characteristics, and are genuine or compatible. It is assumed that a certain developing cartridge 4 has been installed, and the characteristics excluding the change due to the degree of use of the toner contained in the developing cartridge 4 have been found. Therefore, if NO is determined in S104, the printer 100A sets the speed ratio to a medium speed ratio that is smaller than the high speed ratio and larger than the low speed ratio, and stores the speed ratio in the NVRAM 34 (S110). In this case, the change due to the degree of use of the toner stored in the developing cartridge 4 is not known, and the developing cartridge 4 corresponds to an example of a cartridge whose toner characteristics are unknown, and S110 is an example of a setting process. It corresponds to. As a result, the degree of use of the toner contained in the developing cartridge 4 is not known, and when the number of rotations of the remaining developing roller up to a predetermined number of rotations, which is a guideline for developing problems, becomes uncertain, Since the rotation speed is slowed down, development problems can be made less likely to occur.

  Then, the printer 100A overwrites and stores the serial number read from the memory 73 in the NVRAM 34 (S107), resets the use counter (S108), and ends the speed ratio determination process. In this case, the information indicating the degree of use stored in the use counter thereafter is reference information indicating the degree of use after replacement of the old product, and the toner characteristics are unknown only by this information.

  On the other hand, if it is determined that the information could not be properly read from the memory 73 (S102: NO), the developing cartridge 4 that is unknown to the printer 100A has been installed, and the amount of change due to the degree of use of the developing cartridge 4 has changed. In addition to the above characteristics, the characteristics excluding the change due to the degree of use of the contained toner become unclear. Therefore, if NO is determined in S102, the printer 100A sets the speed ratio to the smallest low speed ratio and stores the speed ratio in the NVRAM 34 (S112). In this case, the developing cartridge 4 is an example of a cartridge whose toner characteristics are unknown, and S112 is an example of a setting process.

  Further, the printer 100A deletes the serial number stored in the NVRAM 34 (S113). In S113, the printer 100A may rewrite information with unknown serial number instead of erasing. Further, the printer 100A resets the use counter (S108) and ends the speed ratio determination process.

  Next, the procedure of the printing process executed by the printer 100A will be described with reference to the flowchart of FIG. This print processing is executed by the CPU 31 when the printer 100A receives a print instruction via the network IF 37 or the USB IF 38, for example.

  When the printing process is started, the printer 100A first determines whether or not the received printing instruction is an instruction for monochromatic printing using only one color toner (S201). If the printer 100A determines that it is an instruction for color printing instead of a single color (S201: NO), the printer 100A compares the speed ratios set for the developing rollers 61 of the respective colors and determines the slowest speed ratio during printing. The execution speed ratio is a speed ratio of (S202).

  In the printer 100A, the speed ratio is set for each color developing roller 61 in the speed ratio determination process described above. However, as described above, since the developing rollers 61 of the respective colors are driven to rotate by the common motor 57, they rotate at the same rotational speed. Therefore, the printer 100A matches the rotation speeds of the other developing cartridges 4 to the developing cartridge 4 having the slowest rotation speed. That is, the printer 100A sets the smallest speed ratio among the speed ratios set for the developing rollers 61 of the respective colors as the execution speed ratio. Further, the printer 100A determines the rotation speed of the developing roller 61 based on the rotation speed of the photoconductor 51 and the execution speed ratio.

  Then, the printer 100A executes a developing bias setting process for setting a developing bias value to be applied to the developing roller 61 in each color developing device 54 (S203). In the printer 100A, the rotation speed of the developing roller 61 is a common value for each color, but the developing bias value can be a different value for each color.

  Next, the procedure of the developing bias setting process will be described with reference to the flowchart of FIG. If the rotation speed of the developing roller 61 is changed, the amount of toner movement on the photoconductor 51 may change, and the image density may change. Therefore, in the printer 100A, when the rotation speed of the developing roller 61 is changed, the change in image density is suppressed by adjusting the developing bias value.

  For example, when the charging performance is deteriorated due to the deterioration of the toner, there is a possibility that a weakly charged toner or a toner charged to a reverse polarity may be generated. Since the weakly charged toner or the toner charged to the opposite polarity is likely to adhere to the photoconductor 51, the developing density tends to increase due to the deterioration of the toner. That is, when toner deterioration is advanced, the development density change is suppressed by reducing the absolute value of the developing bias as compared with the case where the toner characteristics are good.

  On the other hand, as described above, the printer 100A reduces the speed ratio when the toner characteristics are unknown in the speed ratio determination process. That is, in the developing cartridge 4 determined to have a small speed ratio, the characteristics of the toner are unknown, and there is a possibility that the contained toner is deteriorating. Therefore, the printer 100A reduces the absolute value of the developing bias when the speed ratio is small. The development bias is an example of a print control bias.

  In the development bias setting process, the printer 100A first determines whether or not the execution speed ratio determined in S202 of the printing process is equal to any speed ratio set for each color (S301). If the speed ratio set for each color is the same value, the execution speed ratio is the speed ratio. If it is determined that the execution speed ratio is equal to each speed ratio (S301: YES), the printer 100A does not need to change the development bias value, and thus ends the development bias setting process. In the printer 100A, the developing bias value corresponding to the set speed ratio is set in advance according to the usage of the developing roller 61 and various printing conditions.

  On the other hand, if it is determined that the execution speed ratio is not equal to the speed ratio of each color (S301: NO), the printer 100A determines whether there is a color whose speed ratio is the low speed ratio (S302). In this embodiment, the low speed ratio means that the developing cartridge 4 whose toner characteristics are unknown is mounted. If it is determined that there is a color with the speed ratio being the low speed ratio (S302: YES), the printer 100A sets the development bias value for that color to a predetermined fixed value (S303).

  Specifically, the printer 100A sets the speed ratio to the low speed ratio when reading of the serial number from the memory 73 fails in the speed ratio determination process. In other words, in the developing cartridge 4 with the speed ratio being the low speed ratio, the toner characteristics are unknown, and a suitable developing bias value is unknown. Therefore, when the speed ratio is the low speed ratio, the printer 100A sets the applied developing bias value as a fixed value. The fixed value is a development bias value whose absolute value is smaller than other development bias values. The fixed value is an example of a predetermined print control bias.

  On the other hand, when it is determined that there is no color whose speed ratio is the low speed ratio (S302: NO), or after S303, the printer 100A forms a mark for the color whose speed ratio is not the low speed ratio (S305). S305 is an example of a mark formation process. The printer 100 </ b> A sets the rotation speed of the developing roller 61 and the rotation speed of the photoconductor 51 based on the execution speed ratio, and forms, for example, a 100% density mark on the conveyance belt 7. Then, the printer 100A causes the mark sensor 25 to read the formed mark (S306). S306 is an example of a reading process.

  Then, the printer 100A determines a development bias value based on the mark density of the read result (S307). Specifically, the density of the read result of each color mark is compared with a predetermined 100% density, the development bias value is determined so that the density of the mark approaches 100% density, and the development bias setting process ends. . S307 is an example of a second bias setting process. For toners with unknown characteristics, not only the development bias value is fixed, but for toners with unknown characteristics, adjustment of the development bias value by mark formation and selection of the bias value based on the degree of use should be performed. Therefore, more appropriate development bias control is possible.

  Returning to the description of the printing process in FIG. 5, the printer 100A applies a developing bias to the developing device 54 of each color based on the developing bias value of each color determined in the developing bias setting process of S203. In addition, the printer 100A rotationally drives the developing roller 61 of each color at the rotational speed of the execution speed ratio determined in S202. Then, the printer 100A executes one sheet printing (S205). S205 is an example of a forming process.

  Further, the printer 100A counts up the usage counter for each color according to the usage level of the developing cartridge 4 used for printing one sheet (S206). The use counter is a counter that is reset in S108 of the speed ratio determination process. The printer 100A updates the counter value according to use unless the developing cartridge 4 is replaced. In other words, the printer 100A can acquire the usage level based on the usage counter for the developing cartridge 4 that is newly installed and continues to be used.

  Then, the printer 100A determines whether there is a color for which the counter value of the usage counter exceeds a predetermined threshold (S207). If it is determined that the counter value of the usage counter has exceeded a predetermined threshold (S207: YES), the printer 100A notifies the operator that the toner is near empty for the corresponding color, for example, via the operation panel 40 (S208), and the speed ratio. Is set to a medium speed ratio (S209). On the other hand, when it is determined that the counter value of the usage counter does not exceed the predetermined threshold (S207: NO), the printer 100A does not execute S208 and S209.

  When the developing cartridge 4 is used until the counter value of the usage counter exceeds the threshold value, the toner contained therein has deteriorated to some extent. In other words, there is a high possibility that development characteristics will change due to changes in toner characteristics from the beginning. Therefore, the printer 100A reduces the speed ratio and suppresses development failures.

  Note that the developing cartridge 4 to be determined in S207 is a new cartridge that has been installed in the printer 100A and has been used without being replaced thereafter. The speed ratio is set to the high speed ratio before S207. This is the developing cartridge 4 that has been developed. For the other developing cartridges 4, the determination in S207 is skipped and the process proceeds to the next.

  Then, the printer 100A determines whether printing of the received print job has been completed (S210). If it is determined that printing has been completed (S210: YES), the printer 100A ends the printing process. If it is determined that printing has not been completed (S210: NO), the printer 100A returns to S205 and executes the next printing.

  On the other hand, when the received print instruction is determined to be monochrome printing using only one color toner, such as monochrome printing (S201: YES), the printer 100A is set to a color that uses the execution speed ratio. The speed ratio is set (S212). That is, in single color printing, the printer 100A determines the rotation speed of the developing roller 61 based on the speed ratio of the colors to be used.

  Further, the printer 100A sets the developing bias value to a predetermined fixed value if the speed ratio of the color to be used is a low speed ratio, and determines the usage degree of the developing roller 61 if the speed ratio of the color to be used is not the low speed ratio. (S213). S213 is an example of a first bias setting process. After determining the speed ratio and the development bias, the printer 100A proceeds to S205 and executes printing. In the case of monochromatic printing, the printer 100A executes S206 to S209 only for the colors to be used.

  Next, processing executed by the printer 100B will be described with reference to the flowcharts of FIGS. FIG. 7 is a flowchart of speed ratio determination processing executed by the printer 100B, and FIG. 8 is a flowchart of printing processing executed by the printer 100B. The same processes as those executed by the printer 100A are denoted by the same reference numerals, and description thereof is omitted. The trigger for starting the execution of each process is the same as that of the printer 100A.

  When the execution of the speed ratio determination process in FIG. 7 is started, the printer 100B reads information stored in the memory 73 of the developing cartridge 4 (S101), and determines whether the information has been read (S102). ). In the printer 100B, the information read in S101 includes information indicating the degree of use in addition to the serial number. In this case, S101 is an example of a usage level acquisition process.

  The developing cartridge 4 mounted in the printer 100B includes a writable nonvolatile memory 73. Then, as will be described later, the printer 100B writes information indicating the degree of use in the memory 73 when printing is performed. The written usage degree is stored in the memory 73 even when the developing cartridge 4 is attached or detached. That is, unlike the printer 100A that stores information indicating the degree of use in the printer main body, the developing cartridge 4 stores the information in the printer 100B.

  The printer 100B can acquire the degree of use even when the developing cartridge 4 is replaced by reading the stored contents from the memory 73 of the mounted developing cartridge 4. Therefore, in the printer 100B, it is not necessary to determine a mechanical mechanism for detecting a new product or replacing an old product. Therefore, the printer 100B determines the speed ratio based on the usage degree read from the memory 73.

  If it is determined that the information stored in the memory 73 has been read (S102: YES), the printer 100B determines whether or not the usage level of the developing cartridge 4 exceeds a predetermined threshold value that causes the near empty state. (S401). Then, if the printer 100B determines that it is not in the near empty state because it does not exceed the predetermined threshold value for entering the near empty state (S401: NO), the speed ratio is set to the high speed ratio (S106). The decision process is terminated. If the developing cartridge 4 is not in a nearly empty state, it can be expected that the characteristics of the contained toner are good.

  On the other hand, if it is determined that the printer 100B is in the near empty state because it exceeds the predetermined threshold value for the near empty state (S401: YES), the speed ratio is set to the medium speed ratio (S110), and the speed is set. The ratio determination process ends. In the developing cartridge 4 in the near empty state, there is a high possibility that the characteristics of the stored toner are more deteriorated, so the printer 100B sets a speed ratio smaller than the high speed ratio.

  On the other hand, when it is determined that the information cannot be properly read from the memory 73 (S102: NO), the characteristics of the toner contained in the developing cartridge 4 are unknown. Therefore, the printer 100B sets the speed ratio to the slowest low speed ratio (S112) and ends the speed ratio determination process.

  Next, the procedure of the printing process executed by the printer 100B will be described with reference to the flowchart of FIG. When the printing process is started, the printer 100B first determines whether or not the received print instruction is an instruction for single-color printing using only one color toner (S201). If it is determined that the instruction is for color printing (S201: NO), the printer 100B sets the slowest speed ratio among the colors as the execution speed ratio (S202).

  Then, the printer 100B executes a developing bias setting process for setting a developing bias value applied by the developing device 54 for each color (S203). The development bias setting process is the same as the process described for the printer 100A.

  After the development bias values for the respective colors are determined in S203, the printer 100B executes printing of one sheet (S205). Then, the printer 100B counts up information indicating the degree of use stored in the memory 73 of each developing cartridge 4 (S501). The printer 100B reads information indicating the degree of use from the memory 73, changes the read information to a value increased by a value corresponding to printing of one sheet, and stores the information in the memory 73. Instead of updating the stored contents of the memory 73 for each printing, only the usage is counted up in S501, and the value counted up by the value corresponding to the number of printed sheets is stored in the memory 73 after the job is completed. You may do that.

  Then, based on the value counted up in S501, the printer 100B determines whether or not there is a color whose usage is near empty (S502). That is, the printer 100B determines whether or not there is a color whose usage degree counted up in S501 exceeds a predetermined threshold. The printer 100B executes S502 for all colors for which information could be read from the memory 73.

  If it is determined that the toner is near empty (S502: YES), the printer 100B notifies that the toner is near empty for the corresponding color (S208), and sets the speed ratio of the corresponding color to the medium speed ratio (S209). . If it is determined that it is not near empty (S502: NO), the printer 100B does not execute S208 and S209.

  Then, the printer 100B determines whether printing of the received print job has been completed (S210). If it is determined that printing has been completed (S210: YES), the printer 100B ends the printing process. On the other hand, if it is determined that printing has not been completed (S210: NO), the printer 100B returns to S205 to execute the next printing.

  On the other hand, when it is determined that the received print instruction is monochrome printing (S201: YES), the printer 100B sets the execution speed ratio to the speed ratio set to the color to be used (S212). Further, the printer 100B executes printing with the development bias value set to the color using the development bias value (S213). In the case of monochrome printing, the printer 100B executes S501 and S502 only for the colors to be used.

  Note that, as a setting for reducing the rotation speed of the developing roller 61, it is conceivable to reduce the printing speed as a whole in order to suppress development problems. However, if this is done, productivity is likely to decrease, and there is a high possibility that the waiting time until a printed matter is obtained becomes long. Therefore, the printer 100 suppresses the decrease in productivity by changing only the rotation speed of the developing roller 61 without changing the rotation speed of the photoconductor 51. That is, in the printer 100, the rotation speed of the developing roller 61 is decreased by reducing the speed ratio that is the ratio between the rotation speed of the photoconductor 51 and the rotation speed of the developing roller 61. As a result, it is expected to suppress development problems such as toner leakage while maintaining the printing speed.

  As described above in detail, the printer 100 according to this embodiment forms a toner image using the toner stored in the developing cartridge 4. The printer 100 compares the speed ratio, which is the ratio of the rotation speed of the developing roller 61 with respect to the rotation speed of the photosensitive member 51, when the characteristics of the toner contained in the mounted developing cartridge 4 are unknown, and when the characteristics are not unknown. To set a small speed ratio. That is, the speed ratio is set so that the development failure does not occur even when the deterioration of the toner is advanced when the number of rotations of the development roller allowed until the development failure occurs is inaccurate. Therefore, even when the developing cartridge 4 whose toner characteristics are unknown is installed, it can be expected that occurrence of development problems is suppressed.

  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, the present invention is not limited to a printer, and can be applied to any apparatus having an image forming function in an electrophotographic system, such as a copying machine, a multifunction machine, and a FAX apparatus. Further, the printer is not limited to a color printer, and may be a monochrome printer.

  In the present embodiment, three speed ratios are provided. However, two speed ratios or four or more speed ratios may be used. For example, the medium speed ratio and the low speed ratio may be the same speed ratio. In other words, even if the serial number can be read, the speed ratio may be set to the low speed ratio in the developing cartridge 4 whose degree of use is unknown. Alternatively, if the serial number can be read, the speed ratio may not be reduced regardless of the degree of use. In that case, it is not necessary to change the speed ratio according to the degree of use, and the determinations in S207 and S502 and S208 and S209 are unnecessary.

  In this embodiment, the developing roller 61 of each color is rotated by the common motor 57, but may have an individual motor. In that case, there is no need to set the execution speed ratio, and S202 and S203 are unnecessary.

  In this embodiment, the speed ratio is reduced by maintaining the rotational speed of the photosensitive member 51 and decreasing the rotational speed of the developing roller 61. However, the rotational speed of the photosensitive member 51 may be changed. For example, the speed ratio can be reduced by increasing the rotation speed of the photoconductor 51. Further, both the rotational speed of the photoconductor 51 and the rotational speed of the developing roller 61 may be changed. However, changing the rotation speed of the photosensitive member 51 makes the control complicated. In order to suppress development problems without reducing productivity, it is preferable to maintain the rotational speed of the photoconductor 51 and decrease the rotational speed of the developing roller 61.

  Further, the cartridge is not limited to the developing cartridge 4. The cartridge only needs to include at least a toner container, and may be, for example, a toner cartridge including only a toner container or a process cartridge including the process unit 50.

  Further, the adjustment of the printing control bias is not limited to the developing bias value, and for example, the charging bias value may be adjusted.

  In this embodiment, the developing bias value is set to a fixed value for the developing cartridge 4 having a speed ratio of low speed, but a mark may be formed for the developing cartridge 4 having a low speed ratio. If the development bias is determined by forming a mark, there is a high possibility that the development density will be more appropriate. However, in the developing cartridge 4 having a low speed ratio, there is a high possibility that the toner has been deteriorated, and if it is used for forming a mark, the deterioration may further increase. From the viewpoint of suppressing the progress of toner deterioration as much as possible, it is desirable not to form marks.

  The processing disclosed in the embodiments may be executed by a single CPU, a plurality of CPUs, hardware such as an ASIC, or a combination thereof. Further, the processing disclosed in the embodiment can be realized in various modes such as a recording medium or a method recording a program for executing the processing.

  Even if the toner characteristics are not known, the usage of the developing roller in the cartridge may exceed the threshold value. When such a cartridge is mounted, there is a risk that development problems will occur early.

  The present invention includes a photosensitive member, a developing roller, and a storage portion that stores toner, and forms a toner image using toner supplied from the storage portion to the photosensitive member via the developing roller. In the image forming apparatus including at least the forming unit in which the storage unit is configured by a cartridge and a control unit, the control unit is configured to control a degree of use of the developing roller in the mounted cartridge. A determination process for determining whether or not the threshold is exceeded, and if it is determined in the determination process that the usage of the development roller in the cartridge exceeds the threshold, the development roller A speed ratio, which is a ratio of rotational speeds, is set when it is determined in the determination process that the degree of use of the developing roller in the cartridge does not exceed a threshold value. A setting process for setting a low speed ratio which is a speed ratio smaller than a specified ratio which is a speed ratio to be formed, a forming process for forming a toner image on the forming unit based on the speed ratio set in the setting process, May be executed.

  An image forming apparatus in which a cartridge for storing toner can be attached and detached, and if the degree of use of the developing roller in the installed cartridge exceeds a threshold value, the speed of the developing roller can be improved even if the toner characteristics are not known. By setting the ratio to a low speed ratio, it can be expected to suppress development defects.

4 Development Cartridge 5 Process Unit 25 Mark Sensor 31 CPU
34 NVRAM
51 Photoconductor 61 Developing Roller 70 Toner Storage Unit 73 Memory 100, 100A, 100B Printer

Claims (12)

A forming unit that includes a photosensitive member, a developing roller, and a storage unit that stores toner, and forms a toner image using toner supplied from the storage unit to the photosensitive member via the developing roller; And wherein at least the forming portion is formed of a cartridge, and
A control unit;
In an image forming apparatus comprising:
The controller is
Determination processing for determining whether the mounted cartridge is a cartridge whose toner characteristics are unknown;
When it is determined in the determination process that the toner characteristics are unknown, the speed ratio, which is the ratio of the rotation speed of the developing roller to the rotation speed of the photosensitive member, is determined. A setting process for setting a low speed ratio that is a speed ratio smaller than a specified ratio that is a speed ratio that is set when it is determined that the cartridge is not unknown;
A forming process for forming a toner image on the forming unit based on the speed ratio set in the setting process;
An image forming apparatus characterized in that The image forming apparatus according to claim 1,
The controller is
Executing identification information acquisition processing for acquiring individual identification information from the memory of the mounted cartridge;
The image forming apparatus according to claim 1, wherein, in the determination process, when the individual identification information cannot be acquired, it is determined that the mounted cartridge is a cartridge with unknown toner characteristics. The image forming apparatus according to claim 2,
There are two types of the low speed ratio: a first low speed ratio and a second low speed ratio in which the rotation speed of the developing roller is faster than the first low speed ratio,
The controller is
In the setting process, when the individual identification information cannot be acquired when it is determined in the determination process that the toner characteristics are unknown, the first low speed ratio is set as the low speed ratio. When the individual identification information can be acquired, the second low speed ratio is set as the low speed ratio. The image forming apparatus according to any one of claims 1 to 3,
A storage unit for storing cartridge individual identification information and a value corresponding to the degree of use of the developing roller corresponding to the individual identification information;
The controller is
A new article judgment process for judging whether or not the mounted cartridge is new;
Identification information acquisition processing for acquiring individual identification information from the memory of the mounted cartridge;
An identification information determination process for determining whether the individual identification information stored in the storage unit includes individual identification information that matches the individual identification information acquired in the identification information acquisition process;
A storage process for storing the individual identification information acquired in the identification information acquisition process in the storage unit after the identification information determination process;
And
In the determination process, if the new article determination process does not determine that the article is new and the identification information determination process determines that there is no individual identification information, the mounted cartridge is a cartridge whose toner characteristics are unknown. And an image forming apparatus. In the image forming apparatus according to any one of claims 1 to 4,
The controller is
In the setting process, when the degree of use of the developing roller in the mounted cartridge exceeds a threshold, the speed ratio is set to the low speed ratio that is a speed ratio smaller than the specified ratio. Image forming apparatus. The image forming apparatus according to claim 5,
The controller is
An image forming apparatus that executes a usage level acquisition process for acquiring a usage level of a developing roller from a memory of a mounted cartridge. The image forming apparatus according to any one of claims 1 to 6,
The controller is
If the installed cartridge is a cartridge whose toner characteristics are unknown, a predetermined print control bias is set. If the installed cartridge is not a cartridge whose toner characteristics are unknown, it is installed. A first bias setting process for setting a print control bias in the forming unit based on the usage of the developing roller in the cartridge;
An image forming apparatus characterized in that The image forming apparatus according to any one of claims 1 to 6,
The controller is
A mark forming process for forming a predetermined mark at the speed ratio set in the setting process in the forming unit;
A reading process for reading the mark formed by the mark forming process;
If the installed cartridge is a cartridge whose toner characteristics are unknown, a predetermined print control bias is set. If the installed cartridge is not a cartridge whose toner characteristics are unknown, the cartridge is mounted. A second bias setting process for executing the reading process on the formed part and setting a print control bias in the forming part based on a reading result of the reading process;
An image forming apparatus characterized in that In the image forming apparatus according to any one of claims 1 to 8,
A plurality of the forming portions, and the rotation speeds of the developing rollers of all the forming portions used for printing are the same speed,
The controller is
In the setting process, the smallest speed ratio among the forming units used for printing is set as a common speed ratio. The image forming apparatus according to any one of claims 1 to 9,
The controller is
2. An image forming apparatus according to claim 1, wherein when the speed ratio is set to the low speed ratio in the setting process, the rotation speed of the developing roller is slower than when the speed ratio is set to the specified ratio. A toner image is formed using toner supplied from a storage unit to a photosensitive member via a developing roller, and at least the storage unit includes a cartridge.
A determination process for determining whether or not the mounted cartridge is a cartridge whose toner characteristics are unknown;
If it is determined in the determination process that the toner characteristics are unknown, the speed ratio, which is the ratio of the rotation speed of the developing roller to the rotation speed of the photosensitive member, is determined. A setting process for setting a low speed ratio which is a speed ratio smaller than a specified ratio which is a speed ratio set when it is determined that the cartridge is not a cartridge;
A forming process for forming a toner image based on the speed ratio set in the setting process;
A program characterized by having executed. In an image forming method of an image forming apparatus in which a toner image is formed using toner supplied onto a photosensitive member via a developing roller from a container, and at least the container is configured by a cartridge.
A determination step for determining whether the mounted cartridge is a cartridge with unknown toner characteristics;
If it is determined in the determination step that the cartridge has an unknown toner characteristic, the speed ratio, which is the ratio of the rotation speed of the developing roller to the rotation speed of the photoreceptor, is determined, and the toner characteristic is not determined in the determination step. A setting step for setting a low speed ratio that is a speed ratio smaller than a specified ratio that is a speed ratio that is set when it is determined that the cartridge is not a cartridge;
Forming a toner image based on the speed ratio set in the setting step;
An image forming method comprising:

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