Image forming apparatus

Abstract

To provide an image forming apparatus that can prevent the occurrence of an image defect.SOLUTION: An image forming apparatus further comprises a printing rate calculation unit. The printing rate calculation unit divides a transfer area on a transfer target body by a constant width in a main scanning direction, and calculates the printing rate of each of the sections. A control unit calculates, for each of the sections, the integrated printing rate of toner images transferred to the transfer area within a predetermined period, and determines the operating time of aging operations on the basis of the calculated integrated printing rate of each of the sections.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus, such as a copying machine, a printer, a facsimile, or a combination machine thereof, that is equipped with an image carrier. [Background technology]

[0002] A conventional image forming apparatus is disclosed in Patent Document 1. This image forming apparatus includes an image forming unit, a transfer member, and a control unit. The image forming unit includes an image carrier, a charging device, an exposure device, and a developing device.

[0003] The image carrier has a photosensitive layer formed on its surface. The charging device charges the image carrier. The exposure device forms an electrostatic latent image by exposing the image carrier charged by the charging device. The developing device has a developer carrier and an agitating section, and forms a toner image by applying a predetermined development voltage to the image carrier to cause toner to adhere to the electrostatic latent image formed on the image carrier. The developer carrier is disposed opposite the image carrier and carries the developer. The agitating section agitates the developer.

[0004] The transfer member is disposed opposite the image carrier, and applies a predetermined transfer voltage to the transfer member to transfer the toner image formed on the image carrier to the transfer receiver. The toner image transferred to the transfer receiver is then transferred to the transfer paper.

[0005] The control unit divides the toner image to be transferred to the transfer area of ​​the transfer medium into sections of a certain width in the main scanning direction, and predicts the amount of developer to be consumed for each section before the development operation. Based on the predicted amount of developer to be consumed for each section, the control unit advances the supply time of developer to the developer carrier. This makes it possible to reduce a partial decrease in image density by supplying developer to areas where developer is expected to be insufficient. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2014-6520 A Summary of the Invention [Problem to be solved by the invention]

[0007] In the configuration of Patent Document 1, the stirring speed of the stirring section changes depending on the remaining amount of developer. This may cause the developer to be supplied from the stirring section to the developer carrier in time, which may result in image defects.

[0008] SUMMARY OF THE PRESENT DISCLOSURE In view of the above problems, an object of the present invention is to provide an image forming apparatus capable of preventing the occurrence of image defects. [Means for solving the problem]

[0009] In order to achieve the above object, a first configuration of the present invention is an image forming apparatus including an image forming section, a transfer member, and a control section. The image forming section includes an image carrier, a charging device, an exposure device, and a developing device. The image carrier has a photosensitive layer formed on its surface. The charging device charges the image carrier. The exposure device exposes the image carrier charged by the charging device to light to form an electrostatic latent image. The developing device has a developer carrier, a developing container, and an agitating section, and forms a toner image by applying a predetermined development voltage to the image carrier to cause the developer to adhere to the electrostatic latent image formed on the image carrier. The developer carrier is disposed opposite the image carrier and carries a non-magnetic one-component developer. The developing container rotatably supports the developer carrier and contains the developer therein. The agitating section is disposed inside the developing container and agitates the developer. The transfer member is disposed opposite the image carrier, and transfers the toner image formed on the image carrier to the transferee by applying a predetermined transfer voltage. The control unit controls the image forming unit and the transfer member. The control unit is capable of executing an image forming operation for forming an image or an aging operation. The aging operation drives the stirring unit while the image forming operation is stopped. The image forming apparatus further includes a print rate calculation unit. The print rate calculation unit divides the transfer area on the transferee into sections of a certain width in the main scanning direction, and calculates the print rate for each section. The control unit calculates the cumulative print rate of the toner image transferred to the transfer area within a predetermined period for each section, and determines the operation time of the aging operation based on the calculated cumulative print rate for each section.

[0010] In order to achieve the above object, the second configuration of the present invention is an image forming apparatus including an image forming section, a transfer member, a display section, and a control section. The image forming section includes an image carrier, a charging device, an exposure device, and a developing device. The image carrier has a photosensitive layer formed on its surface. The charging device charges the image carrier. The exposure device exposes the image carrier charged by the charging device to light to form an electrostatic latent image. The developing device has a developer carrier, a developing container, and an agitating section, and forms a toner image by applying a predetermined development voltage to the image carrier to cause the developer to adhere to the electrostatic latent image formed on the image carrier. The developer carrier is disposed opposite the image carrier and carries a non-magnetic one-component developer. The developing container rotatably supports the developer carrier and contains the developer therein. The agitating section is disposed inside the developing container and agitates the developer. The transfer member is disposed opposite the image carrier, and transfers the toner image formed on the image carrier by applying a predetermined transfer voltage to the transferee. The display unit displays a message. The control unit controls the image forming unit, the transfer member, and the display unit. The control unit can execute an image forming operation for forming an image or an aging operation. The aging operation drives the stirring unit to stir the developer while the image forming operation is stopped. The image forming apparatus further includes a print rate calculation unit. The print rate calculation unit divides the transfer area on the transferee into sections of a certain width in the main scanning direction, and calculates the print rate for each section. The control unit calculates the cumulative print rate of the toner image transferred to the transfer area within a predetermined period for each section, and when the maximum value of the calculated cumulative print rate for each section exceeds a predetermined threshold value, stops the aging operation and displays on the display unit that the developer is insufficient. Effect of the Invention

[0011] According to the first aspect of the present invention, it is possible to provide an image forming apparatus capable of preventing the occurrence of image defects.

[0012] According to the second aspect of the present invention, it is possible to provide an image forming apparatus capable of notifying an occurrence of an image defect in advance. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing an internal configuration of an image forming apparatus 100 according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a partially enlarged view of the image forming section Pa in FIG. [Diagram 3] FIG. 1 is a block diagram showing an example of a control path of an image forming apparatus 100 according to an embodiment of the present invention. [Figure 4] FIG. 1 is an explanatory diagram illustrating an intermediate transfer belt 8 of an image forming apparatus 100 according to an embodiment of the present invention. [Diagram 5] 1 is a flowchart showing an example of control of the image forming apparatus 100 according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view showing the internal structure of an image forming apparatus 1 according to an embodiment of the present invention.

[0015] The image forming apparatus 100 includes image forming units Pa to Pd, primary transfer rollers (transfer members) 6a to 6d, an image density sensor (density detection device) 45, and a control unit 90.

[0016] The four image forming units Pa, Pb, Pc, and Pd are disposed in order from the upstream side in the transport direction (the left side in FIG. 1) inside the main body of the image forming apparatus 100 (here, a color printer). The image forming units Pa to Pd are provided corresponding to images of four different colors (yellow, cyan, magenta, and black), and sequentially form images of yellow, cyan, magenta, and black through the processes of charging, exposing, developing, and transferring, respectively.

[0017] The image forming units Pa to Pd each include photoconductor drums (image carriers) 1a to 1d, charging devices 2a to 2d, an exposure device 5, and developing devices 3a to 3d. The image forming units Pa to Pd each include photoconductor drums (image carriers) 1a, 1b, 1c, and 1d that carry visible images (toner images) of each color.

[0018] The intermediate transfer belt (transferee) 8 is rotated counterclockwise in FIG. 1 by a driving means (not shown). The intermediate transfer belt (transferee) 8 is provided adjacent to each of the image forming units Pa to Pd. A sheet made of a dielectric resin is used for the intermediate transfer belt 8, and a seamless belt is mainly used.

[0019] The primary transfer rollers (transfer members) 6a to 6d are disposed opposite the photosensitive drums (image carriers) 1a to 1d. A predetermined transfer voltage is applied to the primary transfer rollers (transfer members) 6a to 6d, whereby the visible images (toner images) of each color formed on the photosensitive drums (image carriers) 1a to 1d are transferred to the intermediate transfer belt (transferee) 8. As a result, the toner images formed on the photosensitive drums 1a to 1d are sequentially primarily transferred and superimposed on the intermediate transfer belt 8, which moves while contacting the photosensitive drums 1a to 1d.

[0020] Thereafter, the toner image primarily transferred onto the intermediate transfer belt 8 is secondarily transferred onto a transfer paper P, which is an example of a recording medium, by a secondary transfer roller 9. Furthermore, the transfer paper P onto which the toner image has been secondarily transferred is discharged from the main body of the image forming apparatus 100 after the toner image has been fixed in a fixing unit 13. The photoconductor drums 1a to 1d rotate in a counterclockwise direction in FIG. 1. This causes an image forming process to be performed on each of the photoconductor drums 1a to 1d.

[0021] The transfer paper P onto which the toner image is secondarily transferred is stored in a paper cassette 16 arranged at the bottom of the main body of the image forming apparatus 100. The transfer paper P is transported to a nip portion between the secondary transfer roller 9 and the drive roller 11 of the intermediate transfer belt 8 via a paper feed roller 12a and a pair of registration rollers 12b. A belt cleaner 19 is arranged downstream of the secondary transfer roller 9 in the rotation direction of the intermediate transfer belt 8, and removes toner and the like remaining on the surface of the intermediate transfer belt 8.

[0022] Around the rotatably arranged photoconductor drums 1a to 1d, there are provided charging devices 2a to 2d, an exposure device 5 (see FIG. 1), developing devices 3a to 3d, and cleaning devices 7a to 7d.

[0023] The charging devices 2a to 2d charge the photoconductor drums (image carriers) 1a to 1d. The exposure device 5 exposes the photoconductor drums (image carriers) 1a to 1d charged by the charging devices 2a to 2d to light, thereby forming electrostatic latent images.

[0024] The developing devices 3a to 3d each have a developing roller (developer carrier) 31, and form a toner image by applying a predetermined developing voltage to the developing roller (developer carrier) 31 to cause toner to adhere to the electrostatic latent image formed on the photosensitive drum (image carrier) 1a to 1d. The developing roller (developer carrier) 31 is disposed opposite the photosensitive drum (image carrier) 1a to 1d, and carries a non-magnetic single-component developer.

[0025] The cleaning devices 7a to 7d remove residual developer (toner) and the like remaining on the photosensitive drums 1a to 1d.

[0026] When image data is input from a host device such as a personal computer, first, the surfaces of the photoconductor drums 1a-1d are uniformly charged by the charging devices 2a-2d. Next, the exposure device 5 irradiates light according to the image data, and an electrostatic latent image according to the image data is formed on each of the photoconductor drums 1a-1d. The developing devices 3a-3d are filled with a predetermined amount of non-magnetic single-component developer of each color, yellow, cyan, magenta, and black.

[0027] The developer is supplied onto the photoconductor drums 1a to 1d by the developing devices 3a to 3d, and a toner image corresponding to the electrostatic latent image formed by exposure from the exposure device 5 is formed.

[0028] An electric field is applied between the primary transfer rollers 6a-6d and the photoconductor drums 1a-1d by the primary transfer rollers 6a-6d at a predetermined transfer voltage. As a result, the yellow, cyan, magenta, and black toner images on the photoconductor drums 1a-1d are primarily transferred onto the intermediate transfer belt 8. These four color images are formed with a predetermined positional relationship that is determined in advance for forming a predetermined full-color image. After that, in preparation for the subsequent formation of a new electrostatic latent image, the toner and the like remaining on the surfaces of the photoconductor drums 1a-1d after the primary transfer are removed by the cleaning devices 7a-7d.

[0029] The intermediate transfer belt 8 is stretched over a driven roller 10 on the upstream side and a driving roller 11 on the downstream side, and when the intermediate transfer belt 8 starts to rotate in a predetermined direction (clockwise direction in FIG. 1) with the rotation of the driving roller 11 by a driving motor (not shown), the transfer paper P is transported from the registration roller pair 12b to a nip portion (secondary transfer nip portion) between the driving roller 11 and a secondary transfer roller 9 provided adjacent thereto at a predetermined timing, and the full-color image on the intermediate transfer belt 8 is secondarily transferred onto the transfer paper P. The transfer paper P to which the toner image has been secondarily transferred is transported to a fixing unit 13. In this embodiment, the four rollers Pa to Pd are arranged in a line from the upstream side to the downstream side in the rotation direction of the intermediate transfer belt 8 in a so-called tandem system.

[0030] The transfer paper P transported to the fixing section 13 is heated and pressurized by the fixing roller pair 13a, so that the toner image is fixed to the surface of the transfer paper P, and a predetermined full-color image is formed. The transfer paper P on which the full-color image has been formed is then transported in a different direction by the branching section 14, which branches into multiple directions, and is discharged directly to the discharge tray 17 by the discharge roller pair 15 (or after being sent to the double-sided transport path 18 and having images formed on both sides).

[0031] The image density sensor (density detection device) 45 is disposed upstream of the secondary transfer roller 9 in the rotation direction of the intermediate transfer belt 8. The image density sensor 45 is generally an optical sensor equipped with a light-emitting element such as an LED and a light-receiving element such as a photodiode. When measuring the amount of toner adhesion on the intermediate transfer belt 8, when the light-emitting element irradiates each reference image formed on the intermediate transfer belt 8 with measurement light, the measurement light is reflected by the toner and the belt surface and enters the light-receiving element.

[0032] The density of the toner image detected by the image density sensor (density detection device) 45 is compared with a predetermined reference density to adjust the characteristic value of the developing voltage, etc. In this way, the toner density is corrected (calibrated) for each color.

[0033] (2. Configuration of Image Forming Unit) 2 is a cross-sectional view showing the periphery of the image forming unit 3a mounted on the image forming apparatus 100. In the following description, the image forming unit Pa in FIG. 1 is exemplified, but the configurations of the image forming units Pb to Pd are basically the same, so description thereof will be omitted.

[0034] The photoconductor drum 1a has a cylindrical shape that is rotatably supported with its central axis horizontal, and is rotated at a constant speed around the central axis by a drive unit (not shown). The photoconductor drum 1a has a photosensitive layer made of, for example, an organic photoconductor (OPC) on the outer circumferential surface of a drum tube made of metal such as aluminum. An electrostatic latent image is formed on the outer circumferential surface of the photoconductor drum 1a.

[0035] The charging device 2a is disposed facing the outer peripheral surface of the photosensitive drum 1a with a predetermined gap therebetween. The charging device 2a has a charge wire 221 and a grid electrode 222. The charge wire 221 is a linear electrode extending parallel to the axial direction of the photosensitive drum 1a, and generates a corona discharge between the charge wire 221 and the photosensitive drum 1a. The grid electrode 222 is a lattice-shaped electrode extending in the axial direction of the photosensitive drum 1a, and is disposed between the charge wire 221 and the photosensitive drum 1a. The charging device 2a applies a predetermined charging current to the charge wire 221 to generate a corona discharge, and further applies a predetermined charging voltage to the grid electrode 222, thereby uniformly charging the outer peripheral surface (surface) of the photosensitive drum 1a to a predetermined surface potential.

[0036] The cleaning device 7a is disposed downstream of the primary transfer roller 6a in the rotation direction of the photoconductor drum 1a. The cleaning device 7a includes a collection container 241 and a cleaning roller 242.

[0037] The collection container 241 has an elongated shape extending along the axial direction of the photoconductor drum 1a (the depth direction of the paper in FIG. 2) and is disposed with its longitudinal direction horizontal. The collection container 241 contains the toner and other adhering matter that has been removed and collected from the outer circumferential surface of the photoconductor drum 1a by the cleaning roller 242.

[0038] The developing device 3a is disposed downstream of the charging device 2a with respect to the rotation direction of the photoconductor drum 1a. The developing device 3a includes a developer container 20, an agitating paddle (agitation unit) 23b, a supply roller 23a, and a developing roller 31.

[0039] The developing container 20 has an elongated shape extending along the axial direction of the photosensitive drum 1a (the depth direction of the paper in FIG. 2) and is disposed with its longitudinal direction horizontal. The developing container 20 has an opening 20a in a part facing the photosensitive drum 1a. The developing container 20 contains non-magnetic single-component toner as the developer.

[0040] The developing roller 31 is disposed in the opening 20a of the developing container 20, and a part of it is exposed from the developing container 20. The developing roller 31 extends in the main scanning direction (A1-A2 direction) and is rotatably supported inside the developing container 20. The developing roller 31 is disposed opposite the photosensitive drum 1a and contacts the photosensitive drum 1a. The developing roller 31 is supported by the developing container 20 so as to be rotatable about an axis extending parallel to the axis of the photosensitive drum 1a. The developing roller 31 carries a developer to be supplied to the outer circumferential surface of the photosensitive drum 1a in the region opposite the photosensitive drum 1a. The developing roller 31 rotates in the opposite direction to the photosensitive drum 1a. The developing roller 31 supplies the developer in the developing container 20 to the outer circumferential surface of the photosensitive drum 1a, and develops the electrostatic latent image to form a toner image.

[0041] The stirring paddle (stirring portion) 23b is disposed in the upper portion of the developing container 20, at a position separated from the opening 20a by the developing roller 31 and the supply roller 23a. The stirring paddle 23b is supported by the developing container 20 so as to be rotatable about an axis extending parallel to the photosensitive drum 1a. The stirring paddle 23b further has a flexible film portion 23c extending in the radial direction. The stirring paddle 23b stirs the developer in the developing container 20 by rotating about the axis. This allows the remaining amount of developer in the developing container 20 to be uniform in the main scanning direction (A1-A2 direction).

[0042] That is, the developing device 3a has an agitating paddle (agitating portion) 23b, and the agitating paddle 23b is disposed inside the developing container 20 to agitate the developer. Also, an agitating time Ta, a driving time Tb, and an operating time Tc, which will be described later, are times for rotating the agitating paddle 23b.

[0043] The supply roller 23a is disposed in the lower portion of the developing container 20, between the opening 20a and the stirring paddle 23b. The supply roller 23a is disposed facing the developing roller 31. The supply roller 23a is supported by the developing container 20 so as to be rotatable about an axis extending parallel to the photosensitive drum 1a. The supply roller 23a carries toner to be supplied to the outer circumferential surface of the developing roller 31 in the region facing the developing roller 31. The supply roller 23a rotates in the same direction as the developing roller 31.

[0044] 3 is a block diagram showing an example of a control path used in image forming apparatus 100. Control unit 90 includes at least CPU (Central Processing Unit) 91 as a central processing unit, ROM (Read Only Memory) 92 as a read-only storage unit, RAM (Random Access Memory) 93 as a readable and writable storage unit, temporary storage unit 94 for temporarily storing image data and the like, counter 95, a measurement unit (not shown) for measuring drive time Tb of stirring paddle (stirring unit) 23b, and a plurality of (here, two) I / Fs (interfaces) 96 for transmitting control signals to each device in image forming apparatus 100 and receiving input signals from operation unit 60.

[0045] ROM 92 stores data such as a control program for image forming apparatus 100, numerical values ​​necessary for control, and data that will not be changed while image forming apparatus 100 is in use. RAM 93 stores necessary data generated during the control of image forming apparatus 100, data temporarily required for the control of image forming apparatus 100, and the like. RAM 93 (or ROM 92) also stores the cumulative printing rate of the toner image transferred to transfer area 80, which will be described later, and the drive time Tb of stirring paddle (stirring unit) 23b. Counter 95 accumulates and counts the number of printed sheets.

[0046] The calculation unit (printing rate calculation unit) 97 calculates the printing rate and the cumulative printing rate of the output image based on the image data stored in the temporary storage unit 94. The calculated printing rate and cumulative printing rate are sent to the CPU 91, and the CPU 91 uses them to predict the operation time Tc of the aging operation.

[0047] Furthermore, the control unit 90 transmits control signals from the CPU 91 through the I / F 96 to each portion and device in the image forming apparatus 100. Furthermore, signals indicating the state of each portion and device and input signals are transmitted to the CPU 91 through the I / F 96. Examples of each portion and device controlled by the control unit 90 include image forming units Pa to Pd, primary transfer rollers 6a to 6d, secondary transfer roller 9, main motor 40, belt drive motor 41, voltage control circuit 51, operation unit 60, etc.

[0048] Image input unit 43 is a receiving unit that receives image data transmitted from a personal computer or the like to image forming apparatus 100. The image signal input from image input unit 43 is converted into a digital signal and then sent to temporary storage unit 94.

[0049] The voltage control circuit 51 is connected to the charging voltage power supply 52, the developing voltage power supply 53, and the transfer voltage power supply 54, and operates each of these power supplies according to an output signal from the control unit 90. Each of these power supplies applies a predetermined voltage to the charging rollers 34 in the charging devices 2a-2d and the developing voltage power supply 53 to the developing rollers 31 in the developing devices 3a-3d according to a control signal from the voltage control circuit 51. The transfer voltage power supply 54 applies a predetermined transfer voltage to the primary transfer rollers 6a-6d and the secondary transfer roller 9, thereby supplying a transfer current necessary for transferring the toner image.

[0050] The operation unit 60 is provided with a liquid crystal display unit 61 and an LED 62 that indicates various states, and the user operates the stop / clear button of the operation unit 60 to stop image formation, and operates the reset button to reset various settings of the image forming apparatus 100 to their default states. The liquid crystal display unit (display unit) 61 indicates the state of the image forming apparatus 100, and displays the image formation status and the number of copies to be printed. Various settings of the image forming apparatus 100 are set from a printer driver of the personal computer.

[0051] 4 is an explanatory diagram showing a transfer area 80 of the intermediate transfer belt 8. The intermediate transfer belt 8 has a transfer area 80 that comes into contact with the transfer paper P, and the transfer paper P is transported in a transport direction (sub-scanning direction) D while in contact with the transfer area 80. At this time, the toner image that has been primarily transferred to the transfer area 80 is secondarily transferred to the transfer paper P.

[0052] The transfer area 80 is divided into a first area 80a, a second area 80b, and a third area 80c at equal intervals in the main scanning direction (A1-A2 direction). The control unit 90 calculates the printing rate for each of the first area 80a, the second area 80b, and the third area 80c based on the image data stored in the temporary storage unit 94. In addition, the control unit 90 calculates the cumulative printing rates Pa, Pb, and Pc within a predetermined period from the calculated printing rates. This makes it possible to determine the bias in the ink consumption amount in the main scanning direction (A1-A2 direction) of the developing roller (developer carrier) 31.

[0053] The control unit 90 also calculates the printing rate in the entire main scanning direction (A1-A2 direction) of the transfer area 80 based on the image data stored in the temporary storage unit 94. The control unit 90 also calculates the integrated printing rate Pt within a predetermined period from the calculated printing rate. This makes it possible to determine the total ink consumption of the developing roller (developer carrier) 31.

[0054] In this embodiment, the printing rate is the printing rate (image density), and the cumulative printing rate is a value obtained by adding up the printing rates within a predetermined period (for example, within a predetermined number of printed sheets or within a predetermined number of rotations of the intermediate transfer belt 8). Specifically, the control unit 90 generates the overall printing rate for each print page and the printing rates for each of the first area 80a, the second area 80b, and the third area 80c, and calculates the cumulative printing rates Pa, Pb, Pc, and Pt by adding up (counting) all pages of the print job within the predetermined period. In addition, when reprinting is performed due to a print medium jam or the like, the printing rate for each print page is added up based on the image data of the reprint.

[0055] In addition, in this embodiment, the transfer area 80 calculates the printing rate and the cumulative printing rate in three sections in the main scanning direction (A1-A2 direction), but the number of sections may be increased to four or more, or may be reduced to two. By increasing the number of sections and calculating the printing rate and the cumulative printing rate for each section, it is possible to accurately determine the bias in the ink consumption amount of the developing roller (developer carrier) 31 in the main scanning direction (A1-A2 direction).

[0056] Incidentally, when printing is performed for a long period of time in a print job with a print rate biased in the main scanning direction (A1-A2 direction), the remaining amount of developer in the developer container 20 is biased in the main scanning direction (A1-A2 direction). For this reason, there is a possibility that the image density will decrease in a part of the main scanning direction (A1-A2 direction).

[0057] The control unit 90 can execute an aging operation in which the stirring paddle (stirring unit) 23b is driven to stir the developer while the image forming operation is stopped. In the aging operation, the stirring paddle (stirring unit) 23b is rotated to convey the developer in the main scanning direction (axial direction of the developing roller 31) while stirring the developer. This makes it possible to equalize the remaining amount of developer in the developing container 20 in the main scanning direction (A1-A2 direction). Note that no developing voltage is applied to the developing roller 31 during the aging operation.

[0058] The control unit 90 calculates the cumulative printing rate of the toner image transferred to the transfer area 80 within a predetermined period for each section, and determines the operation time Tc of the aging operation based on the calculated cumulative printing rate for each section. This shortens the operation time Tc of the aging operation, and efficiently equalizes the remaining amount of developer in the main scanning direction (A1-A2 direction). Therefore, it is possible to provide an image forming apparatus 100 that can prevent the occurrence of image defects.

[0059] Specifically, the control unit 90 calculates the cumulative printing rates Pa, Pb, and Pc for the first region 80a, the second region 80b, and the third region 80c from the printing rates for the first region 80a, the second region 80b, and the third region 80c. From the calculated cumulative printing rates Pa, Pb, and Pc, the bias of the remaining amount of developer in the main scanning direction (A1-A2 direction) in the developing container 20 is predicted. In addition, the control unit 90 calculates the mixing time Ta required to equalize the predicted bias of the remaining amount of developer. In other words, the control unit 90 calculates the mixing time (driving time of the mixing paddle (mixing unit) 23b) Ta required for the mixing paddle (mixing unit) 23b to equalize the bias of the developer in the main scanning direction (A1-A2 direction) based on the cumulative printing rates calculated for each section.

[0060] If the maximum value of the calculated cumulative printing rates Pa, Pb, and Pc is greater than a predetermined threshold value S3, it is determined that the remaining amount of developer in the developing container 20 is highly uneven and that it will be difficult to equalize the unevenness even if the aging operation is performed, and the aging operation is terminated, and a message is displayed on the liquid crystal display unit (display unit) 61 indicating that the developer is insufficient, and that it is time to replace the developing container 20. This makes it possible to avoid performing unnecessary aging operations and notify the user of the appropriate time to replace the developing container 20. Therefore, it is possible to provide an image forming apparatus 100 that can notify the occurrence of image defects in advance.

[0061] Furthermore, the stirring paddle (stirring portion) 23b rotates during the printing operation, and the actual deviation in the remaining amount of developer is smaller than the deviation in the remaining amount of developer predicted based on the cumulative printing rate.

[0062] Therefore, within a predetermined period, the operation time Tc (=Ta-Tb) of the aging operation is determined by subtracting the time Tb during which the stirring paddle (stirring unit) 23b is driven during the printing operation (the driving time of the stirring unit 23) from the stirring time Ta. In other words, the operation time Tc of the aging operation is determined by subtracting the driving time Tb of the stirring unit 23 within the predetermined period from the stirring time Ta. This makes it possible to further shorten the operation time Tc of the aging operation and more efficiently equalize the remaining amount of developer in the main scanning direction (A1-A2 direction).

[0063] Before calculating the cumulative printing rates Pa, Pb, and Pc, the cumulative printing rate Pt in the entire main scanning direction (A1-A2 direction) of the transfer area 80 within a specified period is calculated. The remaining amount of developer in the entire developing container 20 is predicted based on the cumulative printing rate Pt. When there is sufficient toner remaining in the entire developing container 20, there is little possibility that the image density will decrease in part of the main scanning direction (A1-A2 direction) even if the remaining amount of developer is biased in the main scanning direction (A1-A2 direction).

[0064] That is, when the cumulative printing rate of the toner image transferred to the transfer area 80 within a predetermined period in the main scanning direction (A1-A2 direction) is equal to or less than a predetermined threshold, the aging operation is terminated. This makes it possible to avoid unnecessary aging operations and quickly perform image formation operations.

[0065] 5 is a flowchart showing an example of control of the image forming apparatus 100 of this embodiment. The aging operation is performed before or after the image forming operation. In step S1, it is determined whether or not the cumulative printing rate Pt of the toner image transferred to the transfer area 80 within a predetermined period of time in the main scanning direction (A1-A2 direction) is equal to or less than a predetermined threshold value S1.

[0066] If the cumulative printing rate Pt is equal to or less than a predetermined threshold value S1, it is determined that there is little possibility of a decrease in image density even if the remaining amount of developer is unevenly distributed in the main scanning direction (A1-A2 direction), and the aging operation is terminated. On the other hand, if the cumulative printing rate Pt is greater than the predetermined threshold value S1, the process proceeds to step S2. At this time, it is determined that there is an uneven distribution of the remaining amount of developer in the main scanning direction (A1-A2 direction).

[0067] In step S1, it may be further determined whether the cumulative printing rate Pt exceeds a predetermined threshold value S2. The threshold value S2 is a value larger than the threshold value S1, and when the cumulative printing rate Pt is larger than the predetermined threshold value S2, it is determined that the remaining amount of developer in the developing container 20 is small and there is no need to perform the aging operation. At this time, the aging operation is terminated and the liquid crystal display unit (display unit) 61 displays that the developer is insufficient, and displays that it is time to replace the toner containers 4a to 4d.

[0068] In step S2, the control unit 90 calculates the printing rate for each of the first area 80a, the second area 80b, and the third area 80c based on the image data stored in the temporary storage unit 94. In addition, the control unit 90 calculates the cumulative printing rates Pa, Pb, and Pc within a predetermined period from the calculated printing rates.

[0069] In step S3, the control unit 90 judges whether the maximum value (for example, Pa) of the cumulative printing rates Pa, Pb, and Pc is greater than a predetermined threshold value S3. If the maximum value of the cumulative printing rates Pa, Pb, and Pc is greater than the predetermined threshold value S3, it is judged that the remaining amount of developer in the developing container 20 is highly uneven and it is difficult to equalize the unevenness even if the aging operation is performed. At this time, the aging operation is terminated and the liquid crystal display unit (display unit) 61 displays that the developer is insufficient and that it is time to replace the toner containers 4a to 4d. On the other hand, if the maximum value of the cumulative printing rates Pa, Pb, and Pc is equal to or less than the predetermined threshold value S3, the process proceeds to step S4.

[0070] In step S4, a mixing time Ta required for the mixing paddle (mixing unit) 23b to uniformly disperse the developer in the main scanning direction (A1-A2 direction) is calculated based on the integrated printing rates Pa, Pb, and Pc.

[0071] In step S5, the time Tb during which the stirring paddle (stirring unit) 23b is driven during the execution of the printing operation within a predetermined period is calculated (the driving time of the stirring unit 23).

[0072] In step S6, the drive time Tb of the mixing unit 23 is subtracted from the mixing time Ta to determine the operation time Tc (=Ta-Tb) of the aging operation.

[0073] In step S7, the stirring paddle (stirring unit) 23b is rotated until the operation time Tc has elapsed. This allows the remaining amount of developer in the developing container 20 to be uniform in the scanning direction (A1-A2 direction). This prevents the image density from decreasing in a part of the main scanning direction (A1-A2 direction) when the next image forming operation is performed. When the operation time Tc has elapsed, the aging operation is terminated.

[0074] According to this embodiment, the cumulative printing rates Pa, Pb, and Pc of the toner image transferred to the transfer area 80 are calculated for each section, and the operation time Tc of the aging operation is determined based on the cumulative printing rates Pa, Pb, and Pc. This shortens the operation time Tc of the aging operation, and efficiently equalizes the remaining amount of developer in the main scanning direction (A1-A2 direction).

[0075] The present invention is not limited to the above embodiment, and various modifications are possible within the scope of the present invention. For example, in the present embodiment, the stirring unit is composed of the stirring paddle 23b, but is not limited to this. Instead of the stirring paddle 23b, a screw extending in the main scanning direction (A1-A2 direction) may be used to stir the developer. Also, the stirring unit may be configured by providing a plurality of stirring paddles 23b. Also, in the above embodiment, a color printer as shown in FIG. 1 is used as an example of the image forming apparatus 100, but it is not limited to a color printer, and other image forming apparatuses such as monochrome and color copiers, digital multifunction machines, and facsimiles may be used. The effects of the present invention will be described in more detail below with reference to examples. [Industrial Applicability]

[0076] The present invention can be applied to an image forming apparatus that uses a two-component developer containing a toner and a carrier. [Explanation of symbols]

[0077] 1a to 1d Photoconductor drum (image carrier) 2a~2d Charging device 3a~3d developing device 4a~4d Toner container 5 Exposure equipment 6a to 6d Primary transfer roller (transfer member) 7a~7d Cleaning device 8 Intermediate transfer belt (transfer receiving material) 9 Secondary transfer roller 10 Driven roller 11 Drive roller 12a Paper feed roller 12b Registration roller pair 13 Fixing section 13a Fixing roller pair 14 Branch 15 Discharge Roller Pair 16 Paper Cassette 17 Output Tray 18-sided conveyor 19 Belt cleaner 20 Developing container 20a Partition wall 20b opening 25 Mixing section 27 Regulatory Blade 31 Developing roller (developer carrier) 40 Main motor 41 Belt drive motor 43 Image input section 45 Image density sensor (density detection device) 51 Voltage control circuit 52 Charge voltage power supply 53 Development voltage power supply 54 Transfer voltage power supply 60 Control section 61 Liquid crystal display section (display section) 62 LED 80 Transcription Area 80a 1st area 80b 2nd area 80c 3rd area 90 Control section 91 CPU 92 ROM 93 RAM 94 Temporary storage 95 Counter 100 Image forming device P Transfer paper Pa~Pd Image forming section Pt Accumulated printing rate S1, S2, S3 Thresholds Ta Mixing time Tb Operating time Tc operating time

Claims

1. an image carrier having a photosensitive layer formed on its surface; a charging device for charging the image carrier; an exposure device for forming an electrostatic latent image by exposing the image carrier charged by the charging device; a developing device including a developer carrier disposed opposite to the image carrier and carrying a non-magnetic one-component developer, a developing container rotatably supporting the developer carrier and accommodating the developer therein, and a stirring section disposed inside the developing container and stirring the developer, the developing device applying a predetermined developing voltage to the developer carrier to cause the developer to adhere to the electrostatic latent image formed on the image carrier, thereby forming a toner image; an image forming unit including: a transfer member disposed opposite the image carrier and configured to transfer the toner image formed on the image carrier to a transfer target by application of a predetermined transfer voltage; A control unit that controls the image forming unit and the transfer member; In an image forming apparatus comprising: the control unit is capable of executing an image forming operation for forming an image or an aging operation for stirring the developer, The aging operation includes driving the stirring unit while the image forming operation is stopped, A printing rate calculation unit is further provided for dividing the transfer area on the transfer object into sections of a certain width in a main scanning direction and calculating a printing rate for each section, The control unit calculates an accumulated printing rate of a toner image transferred to the transfer area within a specified period for each section, and determines an operating time of the aging operation based on the calculated accumulated printing rate for each section.

2. the printing rate calculation unit is capable of calculating a printing rate in an entire width of the transfer area in a main scanning direction, The image forming apparatus according to claim 1 , wherein the control unit terminates the aging operation when an integrated printing rate in the entire width in the main scanning direction of the toner image transferred to the transfer area within the predetermined period is equal to or less than a predetermined threshold value.

3. Further comprising a measuring unit for measuring the drive time of the stirring unit, the control unit calculates a mixing time required for the mixing unit to uniformly disperse the developer in the main scanning direction based on the integrated printing rate calculated for each section, 3. The image forming apparatus according to claim 1, wherein the operation time of the aging operation is determined by subtracting a driving time of the stirring unit within the predetermined period from the stirring time.

4. an image carrier having a photosensitive layer formed on its surface; a charging device for charging the image carrier; an exposure device for forming an electrostatic latent image by exposing the image carrier charged by the charging device; a developing device including a developer carrier disposed opposite to the image carrier and carrying a non-magnetic one-component developer, a developing container rotatably supporting the developer carrier and accommodating the developer therein, and a stirring section disposed inside the developing container and stirring the developer, the developing device applying a predetermined developing voltage to the developer carrier to cause the developer to adhere to the electrostatic latent image formed on the image carrier, thereby forming a toner image; an image forming unit including: a transfer member disposed opposite the image carrier and configured to transfer the toner image formed on the image carrier to a transfer target by application of a predetermined transfer voltage; A display unit for displaying a message; A control unit that controls the image forming unit, the transfer member, and the display unit; In an image forming apparatus comprising: the control unit is capable of executing an image forming operation for forming an image or an aging operation for stirring the developer, The aging operation includes driving the stirring unit while the image forming operation is stopped, A printing rate calculation unit is further provided for dividing the transfer area on the transfer object into sections of a certain width in a main scanning direction and calculating a printing rate for each section, The control unit calculates an accumulated printing rate of the toner image transferred to the transfer area within a specified period for each section, and when the maximum value of the accumulated printing rate calculated for each section exceeds a specified threshold value, the aging operation is stopped and a message is displayed on the display unit indicating that the developer is insufficient.

Images