JP2017097027A - Image forming apparatus and control method of image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to correct excess or deficiency in the amount of toner to be supplied to a developing part according to the consumption of toner so as to avoid a deterioration in image quality and deterioration in efficiency of print processing.SOLUTION: A frequency recording part 85 records, in a non-volatile storage part 84, information indicating the frequency at which a magnetic permeability sensor 80 has detected magnetic permeability falling out of a target range. A supply control part 82 executes steady supply control of deriving an operation amount after correction in which a standard operation amount determined according to an index value D0 of the consumption of toner is corrected according to the frequency and operates a toner supply part 5 by the operation amount after correction.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electrophotographic image forming apparatus and a control method thereof.

  In general, in an electrophotographic image forming apparatus, a two-component developing method and an interactive touch-down developing unit are known. These developing units contain a developer including toner and a carrier, and develop the electrostatic latent image on the image carrier with the toner. The image forming apparatus further includes a toner replenishing unit that replenishes the developing unit with the toner.

  In the image forming apparatus, it is known that the operation time of the toner replenishing unit is controlled in accordance with an integrated value of the number of pixels of an image to be developed (see, for example, Patent Document 1).

  Furthermore, it is also known that the image forming apparatus determines the remaining amount of the toner in the developing unit based on the detected value of the magnetic permeability of the developer in the developing unit (see, for example, Patent Document 1). ). The magnetic permeability of the developer has a non-linear negative correlation with the ratio of the toner to the carrier.

JP 2011-232390 A

  By the way, when the toner replenishing unit is controlled according to the integrated value of the number of pixels of the output image, the toner replenishing amount to the developing unit may be excessive or insufficient with respect to the toner consumption. An excess or deficiency in the toner replenishment amount causes deterioration in image quality due to a change in the ratio of the toner in the developer.

  Further, when the magnetic permeability of the developer exceeds the upper limit level, forced toner replenishment control may be performed to prevent image quality deterioration. The forcible replenishment control is performed under a situation where printing processing is prohibited. For this reason, the shortage of the toner replenishment amount increases the number of occurrences of the forced replenishment control, which in turn causes a deterioration in printing process efficiency.

  Further, the magnetic permeability of the developer has a strong non-linearity with respect to the toner ratio. For this reason, if the feedback control of the toner replenishment amount is performed using the difference between the detected value of the magnetic permeability sensor and the target value, the toner ratio may be changed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that corrects an excess or deficiency of the toner replenishment amount relative to the toner consumption amount, thereby avoiding deterioration in image quality and print processing efficiency.

  An image forming apparatus according to one aspect of the present invention includes a developing unit, a toner replenishing unit, a magnetic permeability sensor, an index value calculating unit, a frequency recording unit, and a replenishment control unit. The developing unit contains a developer including toner and a carrier, and develops the electrostatic latent image on the image carrier with the toner. The toner replenishing unit replenishes the developing unit with the toner. The magnetic permeability sensor detects the magnetic permeability of the developer in the developing unit. The index value calculation unit calculates an index value of the toner consumption by integrating the number of pixels of the electrostatic latent image. The frequency recording unit records information representing a frequency at which the magnetic permeability sensor detects the magnetic permeability out of a preset target range in a nonvolatile storage unit. The replenishment control unit derives a corrected operation amount in which a standard operation amount determined according to the index value is corrected according to the frequency, and performs a steady replenishment control for operating the toner replenishment unit by the corrected operation amount. Run.

  An image forming apparatus control method according to another aspect of the present invention is a method for controlling an image forming apparatus including the developing unit, the toner replenishing unit, and the magnetic permeability sensor. The control method includes the following steps. One of the steps is to calculate an index value of the toner consumption by integrating the number of pixels of the electrostatic latent image. Another one of the steps is to record information representing the frequency at which the magnetic permeability sensor detects the magnetic permeability out of a preset target range in a nonvolatile storage unit. The other one of the steps is to derive a corrected operation amount in which a standard operation amount determined according to the index value is corrected according to the frequency, and to operate the toner replenishing unit by the corrected operation amount. This is to execute supply control.

  According to the present invention, it is possible to provide an image forming apparatus that corrects the excess or deficiency of the toner replenishment amount with respect to the toner consumption amount, thereby avoiding deterioration of image quality and efficiency of printing processing. Become.

FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment. FIG. 2 is a configuration diagram of the developing unit in the image forming apparatus according to the embodiment. FIG. 3 is a block diagram of control-related equipment in the image forming apparatus according to the embodiment. FIG. 4 is a flowchart illustrating an example of a procedure of unsteady supply control in the image forming apparatus according to the embodiment. FIG. 5 is a flowchart illustrating an example of a procedure of steady supply control in the image forming apparatus according to the embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the following embodiment is an example which actualized this invention, Comprising: It does not have the character which limits the technical scope of this invention.

[Configuration of Image Forming Apparatus 10]
First, the configuration of the image forming apparatus 10 according to the embodiment will be described with reference to FIGS.

  The image forming apparatus 10 is an electrophotographic image forming apparatus that forms an image on a sheet 9. The sheet 9 is a sheet-like image forming medium such as paper, an envelope, and an OHP sheet.

  The image forming apparatus 10 includes a sheet supply unit 2, a sheet conveyance unit 3, an image formation unit 4, a toner supply unit 5, a control unit 8, and the like in the main body unit 100.

  The control unit 8 controls the sheet supply unit 2, the sheet conveyance unit 3, the image forming unit 4, and the toner supply unit 5.

  An image forming apparatus 10 shown in FIG. 1 is a tandem image forming apparatus and a color printer. Therefore, the image forming unit 4 includes a plurality of single-color image forming units 4x corresponding to cyan, magenta, yellow, and black colors. Further, the image forming unit 4 includes an optical scanning unit 40, a fixing unit 49, and the like.

  Further, the image forming unit 4 includes an intermediate transfer belt 48, a secondary transfer unit 481, and a secondary cleaning unit 482.

  In the sheet supply unit 2, the sheet delivery unit 22 sends out the sheet 9 stored in the sheet cassette 21 to the conveyance path 30.

  In the sheet conveyance unit 3, each of the plurality of conveyance rollers 31 conveys the sheet 9 along the conveyance path 30. Further, one transport roller 31 discharges the sheet 9 after image formation from the main body 100 to the discharge tray 101.

  In each monochromatic image forming unit 4x, the drum-shaped photoconductor 41 rotates, and the charging unit 42 uniformly charges the surface of the photoconductor 41. Further, the optical scanning unit 40 writes an electrostatic latent image on the surface of the photoconductor 41, and the developing unit 43 develops the electrostatic latent image on the surface of the photoconductor 41 with the toner 91. As a result, a toner image is formed on the surface of the photoreceptor 41. The photoconductor 41 is an example of an image carrier.

  The toner replenishing unit 5 is a device that replenishes the developing unit 43 with toner 91. A plurality of toner replenishing units 5 replenish cyan, magenta, yellow, and black toners 91 to the developing unit 43, respectively.

  The toner replenishing unit 5 includes a replenishing container 51 that accommodates toner 91 and a toner conveying unit 52 that conveys the toner 91 in the replenishing container 51 to the developing unit 43. For example, the toner transport unit 52 may be a screw transport unit that transports the toner 91 by rotating. The screw conveying unit includes a rotation shaft and a blade portion formed so as to spirally extend on the outer peripheral surface of the rotation shaft.

  In each monochrome image forming unit 4x, the primary transfer unit 45 transfers the toner image from the surface of the photoreceptor 41 to the intermediate transfer belt 48. On the intermediate transfer belt 48, the toner image is transferred from each of the plurality of photoconductors 41. As a result, a color image in which the toner images of the respective colors are superimposed is formed on the intermediate transfer belt 48. The primary cleaning unit 47 removes the toner 91 remaining on the surface of the photoreceptor 41.

  The secondary transfer unit 481 transfers the color image formed on the intermediate transfer belt 48 to the sheet 9 in the conveyance path 30. The secondary cleaning unit 482 removes the toner 91 remaining on the intermediate transfer belt 48.

  The fixing unit 49 heats the toner image on the sheet 9 in the conveyance path 30 to fix the color image on the sheet 9.

  The developing unit 43 shown in FIGS. 1 and 2 executes a developing process using a developer 90 including a toner 91 and a carrier 92. The developer 90 is a so-called two-component developer.

  The carrier 92 is a granular material having magnetism. For example, the carrier 92 may be a granular body including a granular magnetic body and a synthetic resin film such as an epoxy resin coated on the surface of the magnetic body.

  As shown in FIG. 2, in the developing unit 43, the developing container 4300 contains the developer 90, and the magnetic roller 430 and the two stirring members 432 rotate within the developing container 4300.

  The two stirring members 432 are stirred while circulating the developer 90 in the developing container 4300. The magnetic roller 430 rotates while carrying the developer 90. The magnetic roller 430 develops the electrostatic latent image by supplying the charged toner 91 of the carried developer 90 to the surface of the photoreceptor 41.

  The developing unit 43 shown in FIG. 2 is a two-component developing type device in which the magnetic roller 430 functions as a developing roller that supplies toner to the photoreceptor 41.

  Note that the developing unit 43 of the image forming apparatus 10 may be a so-called interactive touchdown type apparatus. In this case, the developing unit 43 includes a toner carrying roller that carries the toner 91 supplied from the magnetic roller 430. The toner carrying roller functions as the developing roller that supplies toner to the photoreceptor 41.

  In the developer container 4300, the blade 433 limits the thickness of the developer 90 carried by the magnetic roller 430. The carrier 92 remaining on the magnetic roller 430 after the development is collected in the developing container 4300. Therefore, as the remaining amount of the toner 91 in the developing container 4300 decreases, the ratio of the carrier 92 in the developer 90 increases and the ratio of the toner 91 decreases.

  In the following description, the ratio of the weight of the toner 91 to the weight of the carrier 92 in the developer 90 per unit volume is referred to as a toner ratio.

  The image forming apparatus 10 includes a magnetic permeability sensor 80 that detects the magnetic permeability of the developer 90 in the developing container 4300. The magnetic permeability sensor 80 is disposed outside the developing container 4300.

  The detected value of the magnetic permeability sensor 80 changes according to the ratio of the carrier 92 in the developer 90. In other words, the detected value of the magnetic permeability sensor 80 represents the toner ratio of the developer 90.

  That is, when the magnetic permeability detected by the magnetic permeability sensor 80 is high, the toner ratio is low. On the other hand, when the magnetic permeability detected by the magnetic permeability sensor 80 is low, the toner ratio is high. Therefore, the detected value of the magnetic permeability sensor 80 becomes an index value of the remaining amount of toner in the developing container 4300.

  As shown in FIG. 2, the control unit 8 includes a print control unit 81, a replenishment control unit 82, an image processing unit 83, a data storage unit 84, and the like. For example, the print control unit 81, the replenishment control unit 82, and the image processing unit 83 are one or more of an MPU (Micro Processor Unit), an ASIC (Application Specific Integrated Circuit), and a DSP (Digital Signal Processor) that execute a program. It may be configured by a combination of

  The print control unit 81 executes the printing process by controlling the image forming unit 4. The replenishment control unit 82 controls the toner replenishing unit 5 based on the consumption index value D0 supplied from the image processing unit 83. This control is executed following the printing process or in parallel with the printing process. Hereinafter, this control is referred to as steady supply control. Details of the consumption index value D0 and the steady replenishment control will be described later.

  Further, the replenishment control unit 82 executes the forced replenishment control when the magnetic permeability sensor 80 detects a magnetic permeability that exceeds a preset development upper limit level. The forced replenishment control is control for prohibiting development processing and operating the toner replenishing unit 5 until the magnetic permeability detected by the magnetic permeability sensor 80 falls below a preset first recovery level.

  Further, the replenishment control unit 82 executes replenishment prohibition control when the magnetic permeability sensor 80 detects a magnetic permeability that is lower than a preset development lower limit level. The replenishment prohibition control is a control for prohibiting the operation of the toner replenishing unit 5 until the magnetic permeability detected by the magnetic permeability sensor 80 exceeds a preset second recovery level.

  The first recovery level and the second recovery level are magnetic permeability higher than the development lower limit level and lower than the development upper limit level. Further, it is conceivable that the first recovery level and the second recovery level have the same magnetic permeability, or that the first recovery level has a higher magnetic permeability than the second recovery level.

  The image processing unit 83 executes image data processing. For example, the image processing unit 83 converts print job data obtained from an external device through a communication unit (not shown) into image data for printing such as raster data used for the print processing. The image data is transmitted from the image processing unit 83 to the print control unit 81.

  The image processing unit 83 includes an index value calculation unit 831 that calculates a consumption index value D0 that is an index value of the consumption amount of the toner 91. The index value calculation unit 831 calculates the consumption index value D0 by integrating the number of pixels of the electrostatic latent image, that is, adding the number of pixels of the developed image.

  For example, each time an image is formed on one page of the sheet 9, the index value calculation unit 831 calculates the number of pixels of the developed image per page as the consumption index value D0. The consumption index value D0 is transmitted from the index value calculation unit 831 to the supply control unit 82.

  It is also conceivable that the consumption index value D0 is a printing rate representing the ratio of the number of pixels of the developed image to the total number of pixels in one page of the maximum size sheet 9. The printing rate is also an example of an index value obtained by integrating the number of pixels of the electrostatic latent image.

  The data storage unit 84 is a non-volatile storage unit that stores various data. Furthermore, the data storage unit 84 is also a storage unit that can read and write various data by the supply control unit 82 and the image processing unit 83.

  By the way, when the toner replenishing unit 5 is controlled according to the integrated value of the number of pixels of the output image, there may be an excess or deficiency in the replenishment amount of the toner 91 to the developing unit 43 with respect to the consumption amount of the toner 91. An excess or deficiency in the replenishment amount of the toner 91 causes deterioration in image quality due to a change in the ratio of the toner 91 in the developer 90.

  Further, when the magnetic permeability of the developer 90 exceeds the upper limit level, the forced replenishment control of the toner 91 may be performed in order to prevent image quality deterioration. The forcible replenishment control is performed under a situation where printing processing is prohibited. For this reason, the shortage of the replenishment amount of the toner 91 increases the number of occurrences of the forced replenishment control, which in turn causes a deterioration in printing process efficiency.

  Further, the magnetic permeability of the developer 90 has a strong non-linearity with respect to the ratio of the toner 91. For this reason, if the feedback control of the replenishment amount of the toner 91 is performed using the difference between the detected value of the magnetic permeability sensor 80 and the target value, the ratio of the toner 91 may be changed.

  On the other hand, if the image forming apparatus 10 is employed, the excess or deficiency of the replenishment amount of the toner 91 to the developing unit 43 relative to the consumption amount of the toner 91 is corrected, thereby avoiding the deterioration of the image quality and the deterioration of the efficiency of the printing process. The details will be described below.

  In the present embodiment, the control unit 8 includes a frequency recording unit 85 that executes a frequency recording process. The frequency recording process is a process of recording, in the data storage unit 84, frequency information D1 indicating the frequency at which the magnetic permeability sensor 80 detects a magnetic permeability that is out of a preset target range.

[Unsteady supply control]
In the present embodiment, the control unit 8 performs unsteady supply control including the frequency recording process, the forced supply control, and the supply prohibition control based on the detection value of the magnetic permeability sensor 80. The unsteady replenishment control is control that becomes effective when the magnetic permeability sensor 80 deviates from a preset range.

  Hereinafter, an example of the procedure of the unsteady supply control will be described with reference to the flowchart shown in FIG. In the following description, S11, S12,... Represent identification codes of steps executed by the control unit 8 in the unsteady supply control.

<Step S11>
In the unsteady supply control, the frequency recording unit 85 monitors whether or not the magnetic permeability sensor 80 detects a magnetic permeability that is out of a preset target range.

  For example, it is conceivable that the lower limit of the target range is a magnetic permeability higher than the development lower limit level. Furthermore, it is conceivable that the upper limit of the target range is a magnetic permeability lower than the development upper limit level.

<Step S12>
When the magnetic permeability sensor 80 detects a magnetic permeability outside the target range, the frequency recording unit 85 records the frequency information D1 in the data storage unit 84. In the present embodiment, the frequency recording unit 85 distinguishes the high level frequency D11 and the low level frequency D12 and records them as frequency information D1.

  The high level frequency D11 is a frequency at which the magnetic permeability sensor 80 detects a magnetic permeability exceeding the target range. The low level frequency D12 is a frequency at which a magnetic permeability lower than the target range is detected.

  The high level frequency D11 is, for example, the cumulative number of times that the magnetic permeability sensor 80 has detected a magnetic permeability that exceeds the target range. It is also conceivable that the high level frequency D11 is the number of times that the magnetic permeability sensor 80 has detected a magnetic permeability exceeding the target range in the most recent predetermined period.

  The low level frequency D12 is, for example, the cumulative number of times that the magnetic permeability sensor 80 has detected the magnetic permeability below the target range. It is also conceivable that the low level frequency D12 is the number of times that the magnetic permeability sensor 80 has detected a magnetic permeability below the target range in the most recent predetermined period.

<Steps S13 to S15>
After the magnetic permeability sensor 80 detects the magnetic permeability outside the target range, the frequency recording unit 85 executes the following three determination processes as needed.

  The first determination process is a process of determining whether or not the magnetic permeability sensor 80 detects a magnetic permeability exceeding the upper limit of development (S13). The second determination process is a process of determining whether or not the magnetic permeability sensor 80 detects a magnetic permeability that is lower than the lower limit of development (S14). The third determination process is a process of determining whether or not the magnetic permeability sensor 80 detects a magnetic permeability within a preset recovery level range (S15).

  The lower limit of the recovery level range is larger than the lower limit of the target range and smaller than the upper limit of the target range. Further, the upper limit of the recovery level range is smaller than the upper limit of the target range and larger than the lower limit of the recovery level range.

  The recovery level range is the same range as the range from the second recovery level to the first recovery level, or a range including the range from the second recovery level to the first recovery level.

  When the frequency recording unit 85 determines in step S15 that the magnetic permeability sensor 80 has detected the magnetic permeability within the recovery level range, the frequency recording unit 85 repeats the processing from step S11.

<Step S16>
When the frequency recording unit 85 determines that the magnetic permeability sensor 80 has detected a magnetic permeability below the lower limit of development, the replenishment control unit 82 executes the replenishment prohibition control. As a result, the operation of the toner replenishing unit 5 is prohibited until the magnetic permeability detected by the magnetic permeability sensor 80 exceeds the second recovery level. During the period when the operation of the toner replenishing unit 5 is prohibited, the steady replenishment control is not executed.

  When the magnetic permeability detected by the magnetic permeability sensor 80 exceeds the second recovery level, the process from step S11 by the frequency recording unit 85 is repeated.

<Step S17>
When the frequency recording unit 85 determines that the magnetic permeability sensor 80 has detected a magnetic permeability that exceeds the upper limit of development, the replenishment control unit 82 executes the forced replenishment control. Thus, the toner replenishing unit 5 operates and the development processing is not performed until the magnetic permeability detected by the magnetic permeability sensor 80 falls below the first recovery level.

  When the magnetic permeability detected by the magnetic permeability sensor 80 falls below the first recovery level, the process from step S11 by the frequency recording unit 85 is repeated.

[Steady replenishment control]
Next, an example of the procedure of the steady supply control will be described with reference to the flowchart shown in FIG. In the following description, S21, S22,... Represent identification codes of steps executed by the control unit 8 in the steady supply control.

<Step S21>
When the printing process is performed, the index value calculation unit 831 calculates the consumption index value D0.

<Step S22>
In addition, the replenishment control unit 82 acquires the frequency information D1 from the data storage unit 84.

<Step S23>
Further, the replenishment control unit 82 derives a corrected operation amount V1 in which the standard operation amount V0 of the toner replenishment unit 5 determined according to the consumption index value D0 is corrected according to the high level frequency D11 and the low level frequency D12.

  The operation amount of the toner supply unit 5 is represented by the product of the operation speed and the operation time of the toner supply unit 5. For example, when the toner replenishing unit 5 conveys the toner 91 by the screw conveying unit, the operation speed of the toner replenishing unit 5 is the rotational speed of the screw conveying unit.

  In the present embodiment, the operation speed of the toner replenishing unit 5 is constant. In this case, the standard operation amount V0 and the corrected operation amount V1 are synonymous with the operation time of the toner supply unit 5.

  It should be noted that the operation time of the toner replenishing unit 5 in one unit of the steady replenishment control is fixed, and the standard operation amount V0 and the corrected operation amount V1 are set as the operation speed of the toner replenishment unit 5. Absent.

  For example, it is conceivable that the replenishment control unit 82 calculates the corrected operation amount V1 by applying the consumption index value D0, the high level frequency D11, and the low level frequency D12 to the following equation (1).

  V1 = α * D0 + β1 * D11−γ1 * D12 ___ (1)

  In the equation (1), the replenishment coefficient α and the first correction coefficients β1 and γ1 are coefficients set in advance. The replenishment coefficient α represents a standard operation amount of the toner replenishing unit 5 necessary for replenishing an amount of toner 91 corresponding to D0 = 1.

  The first correction coefficients β1 and γ1 are coefficients for correcting the operation amount of the toner replenishing unit 5 every time one unit of the steady replenishment control is performed with the high level frequency D11 and the low level frequency D12. In the present embodiment, one unit of the steady replenishment control is the steady replenishment control corresponding to the printing process for one page.

  Further, it is conceivable that the replenishment control unit 82 calculates the corrected operation amount V1 by applying the consumption index value D0, the high level frequency D11, and the low level frequency D12 to the following equation (2).

  V1 = (α + β2 * D11−γ2 * D12) * D0 + β1 * D11−γ1 * D12 ___ (2)

  In the equation (2), the replenishment coefficient α, the first correction coefficients β1, γ1, and the second correction coefficients β2, γ2 are preset coefficients. The replenishment coefficient α and the first correction coefficients β1 and γ1 are the same coefficients as those in the equation (1).

  The second correction coefficients β2 and γ2 are coefficients for correcting the replenishment coefficient α with the high level frequency D11 and the low level frequency D12.

  Further, it is conceivable that the replenishment control unit 82 calculates the corrected operation amount V1 by applying the consumption index value D0, the high level frequency D11, and the low level frequency D12 to the following equation (3).

  V1 = (α + β2 * D11−γ2 * D12) * D0 ___ (3)

  In the equation (3), the replenishment coefficient α and the second correction coefficients β2 and γ2 are preset coefficients. The replenishment coefficient α and the second correction coefficients β2 and γ2 are the same coefficients as the coefficients of the equation (2).

  The expression (1) is an expression based on the idea that the main cause of the excess or deficiency of the replenishment amount of the toner 91 is an error in the replenishment amount that occurs almost uniformly for each unit of the steady replenishment control.

  In the equation (2), the main causes of the excess and deficiency of the toner 91 replenishment amount are the error in the replenishment amount that occurs substantially constant for each unit of regular replenishment control, and the replenishment amount per unit operation of the toner replenishment unit 5. It is an expression based on the idea that both are errors.

  Expression (3) is an expression based on the idea that the main cause of the excess or deficiency of the replenishment amount of the toner 91 is an error in the replenishment amount per unit operation of the toner replenishing unit 5.

  For example, if the formula (2) is adopted, it is possible to perform the supply control of the toner 91 in consideration of the above two errors that are considered to be the cause of the excessive or insufficient supply amount of the toner 91.

  Expressions (1) to (3) include a term “α * D0”. This “α * D0” is the standard operation amount V0. That is, in the initial state of the image forming apparatus 10, D11 and D12 are zero, and the operation amount of the toner replenishing unit 5 in the steady replenishment control is the standard operation amount V0. In the equations (1) to (3), the motion amount calculated by the portion other than the term “α * D0” is the correction amount for the standard motion amount V0.

  Further, the replenishment control unit 82 that employs any one of the formulas (1) to (3) is configured to use individual correction coefficients (β1, β2) for the high level frequency D11 and the low level frequency D12 in the steady replenishment control. The standard operation amount V0 is corrected by applying (γ1, γ2).

  In the above case, the correction coefficients β1, β2 corresponding to the high level frequency D11 and the correction coefficients γ1, γ2 corresponding to the low level frequency D12 can be set to different values.

  In general, when the toner ratio becomes too small, the adverse effect on the image quality is larger than when the toner ratio becomes too large. Therefore, the correction coefficients β1 and β1 corresponding to the high level frequency D11 can be set to values larger than the correction coefficients γ1 and γ2 corresponding to the low level frequency D12. Thereby, the correction gain of the replenishment amount of the toner 91 when the toner ratio becomes too small is increased.

  By the way, the correction by the part of (β2 * D11−γ2 * D12) in the formula (2) is an example of a first correction for correcting an amount proportional to only the frequencies D11 and D12. Further, the correction by the part of (α + β1 * D11−γ1 * D12) * D0 in the formula (2) is an example of a second correction for correcting the amounts proportional to the frequencies D11 and D12 and the consumption index value D0. Therefore, the replenishment control unit 82 that employs the equation (2) corrects the standard operation amount V0 by both the first correction and the second correction in the steady replenishment control.

  On the other hand, the replenishment control unit 82 that employs the equation (1) corrects the standard operation amount V0 only by the first correction in the steady replenishment control. Further, the replenishment control unit 82 that employs the expression (3) corrects the standard operation amount V0 only by the second correction in the steady replenishment control.

  For example, the supply coefficient α and the correction coefficients β1, β2, γ1, and γ2 may be constants. On the other hand, it is also conceivable that the replenishment coefficient α is a constant, and the correction coefficients β1, β2, γ1, and γ2 are coefficients that are set according to the operation performance of the image forming apparatus 10.

  For example, the consumption index value D0 until the magnetic permeability detected by the magnetic permeability sensor 80 exceeds the development upper limit level and recovers to the development upper limit level or less and then exceeds the development upper limit level again. Can be calculated as the first consumption integrated value. In this case, it is conceivable that the replenishment control unit 82 sets the correction coefficients β1 and β2 according to the first consumption integrated value.

  Similarly, after the magnetic permeability detected by the magnetic permeability sensor 80 falls below the development lower limit level and then recovers to the development lower limit level or higher, the consumption index value until the image processing unit 83 falls below the development lower limit level again. It is conceivable to calculate the integrated value of D0 as the second consumption integrated value. In this case, it is conceivable that the replenishment control unit 82 sets the correction coefficients γ1 and γ2 in accordance with the second consumption integrated value.

  Specifically, the replenishment control unit 82 sets the correction coefficients β1 and β2 to larger values when the first consumption integrated value is smaller than when the first consumption integrated value is large. Further, the replenishment control unit 82 sets the correction coefficients γ1 and γ2 to a larger value when the second consumption integrated value is larger than when the second consumption integrated value is small.

  By setting the correction coefficients β1, β2, γ1, and γ2 as described above, it is possible to reduce the frequency at which the permeability of the developer 90 exceeds the development upper limit level and the frequency below the development lower limit level. . As a result, the number of executions of the forced supply control and the supply prohibition control can be reduced.

  The replenishment control unit 82 applies the consumption index value D0, the high level frequency D11, and the low level frequency D12 to a preset look-up table without using the calculation formula as described above, thereby correcting the operation amount. It is also conceivable to derive V1.

<Step S24>
Next, the replenishment control unit 82 operates the toner replenishment unit 5 by the corrected operation amount V1 derived in step S23. Thereafter, the replenishment control unit 82 stops the toner replenishment unit 5. Thus, one unit of the steady replenishment control is completed.

  The control unit 8 executes the processes of steps S21 to S25 every time one unit of the printing process is performed. However, the steady supply control is not executed when the supply prohibition control is being performed.

  In the initial state of the image forming apparatus 10, the operation amount of the toner replenishing unit 5 in the steady replenishment control is set to a standard operation amount V0 proportional to the consumption index value D0. The consumption index value D0 corresponds to an integrated value of the number of pixels of the output image.

  In the initial state, when an excess or deficiency in the replenishment amount of the toner 91 to the developing unit 43 occurs with respect to the actual consumption amount of the toner 91, the detected value of the magnetic permeability sensor 80 deviates from the target range.

  When the replenishment amount of the toner 91 is insufficient with the standard operation amount V0, the detected value of the magnetic permeability sensor 80 exceeds the target range, so that the replenishment control unit 82 corrects based on the equations (1) to (3). The post operation amount V1 is increased from the standard operation amount V0. Similarly, when the replenishment amount of the toner 91 is too large at the standard operation amount V0, the detected value of the magnetic permeability sensor 80 falls below the target range, so the replenishment control unit 82 sets the corrected operation amount V1 from the standard operation amount V0. Also reduce.

  Accordingly, if the image forming apparatus 10 is employed, the excess or deficiency of the replenishment amount of the toner 91 to the developing unit 43 relative to the consumption amount of the toner 91 is corrected. Thereby, the toner ratio is stabilized within an appropriate range, and deterioration of image quality is avoided.

  Further, the steady replenishment control reduces the frequency at which the detected value of the magnetic permeability sensor 80 deviates from the target range, and thus the frequency at which the detected value of the magnetic permeability sensor 80 exceeds the development upper limit level also decreases. Therefore, the number of occurrences of the forced supply control is reduced. Therefore, deterioration of the efficiency of the printing process is avoided.

  Further, when the upper limit of the target range is lower than the development upper limit level, it is expected that the shortage of toner 91 will be resolved before the control by the replenishment control unit 82 shifts to the forced replenishment control. Thereby, the effect which avoids the deterioration of the efficiency of the said printing process increases more.

[Application example]
In the embodiment shown above, it is also conceivable that the lower limit and the upper limit of the target range have the same magnetic permeability as the development lower limit level and the development upper limit level, respectively. In this case, the frequency information D1 is also information representing the frequency at which the forced supply control is performed.

  Note that the image forming apparatus and the control method for the image forming apparatus according to the present invention can be freely combined within the scope of the invention described in each claim, or the embodiments and application examples described above can be freely combined. It is also possible to configure the application example by appropriately modifying or omitting a part thereof.

2: Sheet feeding unit 3: Sheet conveying unit 4: Image forming unit 4 x: Monochromatic image forming unit 5: Toner replenishing unit 8: Control unit 9: Sheet 10: Image forming apparatus 21: Sheet cassette 22: Sheet sending unit 30: Conveying Path 31: Conveying roller 40: Optical scanning unit 41: Photoconductor 42: Charging unit 43: Developing unit 45: Primary transfer unit 47: Primary cleaning unit 48: Intermediate transfer belt 49: Fixing unit 51: Supply container 52: Toner conveying unit 80: Magnetic permeability sensor 81: Print control unit 82: Replenishment control unit 83: Image processing unit 84: Data storage unit 85: Frequency recording unit 90: Developer 91: Toner 92: Carrier 100: Main body unit 101: Discharge tray 430: Magnetic roller 432: Stirring member 433: Blade 481: Secondary transfer unit 482: Secondary cleaning unit 831: Index value calculation unit 4300: Development Container D0: Consumption index value D1: Frequency information D11: High level frequency D12: Low level frequency V0: Standard motion amount V1: Corrected motion amount β1: First correction coefficient β2: Second correction coefficient

Claims (6)

A developing unit that contains a developer including toner and a carrier, and develops an electrostatic latent image on the image carrier with the toner;
A toner replenishing unit for replenishing the developing unit with the toner;
A magnetic permeability sensor for detecting the magnetic permeability of the developer in the developing section;
An index value calculation unit that calculates an index value of the toner consumption by integrating the number of pixels of the electrostatic latent image;
A frequency recording unit that records information indicating the frequency at which the magnetic permeability sensor detects the magnetic permeability out of a preset target range in a nonvolatile storage unit;
A replenishment control unit for deriving a post-correction operation amount in which a standard operation amount determined according to the index value is corrected according to the frequency, and performing a steady replenishment control for operating the toner replenishment unit by the corrected operation amount; And an image forming apparatus. The replenishment control unit prohibits development processing when the magnetic permeability sensor detects a magnetic permeability that exceeds a predetermined upper development limit level, and the magnetic permeability detected by the magnetic permeability sensor is preset. Forcibly replenishment control to operate the toner replenishment unit until the recovery level is below the recovery level,
The image forming apparatus according to claim 1, wherein an upper limit of the target range is lower than the development upper limit level. The frequency recording unit includes information on a high level frequency that is the frequency at which the magnetic permeability sensor detects the magnetic permeability exceeding the target range, and a low level frequency that is the frequency at which the magnetic permeability is below the target range. Record information and
The said supply control part correct | amends the said standard operation amount by applying a separate correction coefficient with respect to the said high level frequency and the said low level frequency in the said steady supply control. Image forming apparatus.   In the steady replenishment control, the replenishment control unit performs the standard operation amount by both a first correction for correcting an amount proportional to only the frequency and a second correction for correcting an amount proportional to the frequency and the index value. The image forming apparatus according to claim 1, wherein the correction is performed.   In the steady replenishment control, the replenishment control unit performs the standard operation amount by one of a first correction for correcting an amount proportional to only the frequency and a second correction for correcting an amount proportional to the frequency and the index value. The image forming apparatus according to claim 1, wherein the correction is performed. A developing unit that contains a developer including toner and a carrier, and develops an electrostatic latent image on the image carrier with the toner;
A toner replenishing unit for replenishing the developing unit with the toner;
A magnetic permeability sensor for detecting the magnetic permeability of the developer in the developing section, and a control method of an image forming apparatus comprising:
Calculating an index value of the toner consumption by integrating the number of pixels of the electrostatic latent image;
A step of recording information representing the frequency at which the magnetic permeability sensor detects the magnetic permeability out of a preset target range in a nonvolatile storage unit;
A step of deriving a corrected operation amount in which a standard operation amount determined according to the index value is corrected according to the frequency, and performing a steady supply control for operating the toner supply unit by the corrected operation amount; A control method for an image forming apparatus.

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