JP5691510B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  In the conventional electrophotographic image forming apparatus, as techniques for reducing the deterioration of the developer of the developing device that develops the latent image formed on the surface of the image carrier, the techniques described in the following Patent Documents 1 and 2 Is conventionally known.

  In Japanese Patent Application Laid-Open No. 2004-125829 as Patent Document 1, the number of integrated image dots at the time of printing corresponding to 1000 sheets of A4 size is counted, and the image dot ratio to the printable area is 2% or less. A technique is described in which it is determined that the toner is likely to deteriorate, and the deteriorated toner is transferred to and discharged from the photosensitive drum during non-image formation. Patent Document 1 also describes a technique for changing the threshold of the number of integrated image dots when the developing container is in the latter half of the end of life, that is, near the end of the life of the developing container.

  Japanese Patent Laid-Open No. 2009-103970 as Patent Document 2 discloses that when a document having a document printing rate lower than a predetermined value continues, a predetermined amount of toner is forcibly developed and discharged onto the photosensitive drum (3). A technique is described in which the toner is circulated through the developing device without being consumed by discharging the deteriorated toner without being consumed by controlling to supply the same amount of toner each time.

Japanese Patent Application Laid-Open No. 2004-125829 (“0087” to “0090”, “0094” to “0095”, “0188”) JP 2009-103970 A ("0054" to "0056")

  An object of the present invention is to reduce excessive discharge of a developer that has not deteriorated.

In order to solve the technical problem, an image forming apparatus according to claim 1 is provided.
An image carrier,
A latent image forming apparatus for forming a latent image on the surface of the image carrier;
A developing device for developing the latent image on the surface of the image carrier into a visible image;
A replenishing device for replenishing developer to the developing device;
Discharge setting means for setting the amount of developer discharged from the developing device;
A discharged image for forming a latent image on the surface of the image holding member, developing with the developing device, and discharging the developer in the developing device , according to the amount of developer discharged set by the discharge setting means. A discharge control means for the developer to be formed ;
With
The discharge setting unit is configured to determine the discharge amount of the developer based on the image density during the image forming operation from the previous discharge amount setting to the current discharge amount setting and the number of image formations in a preset period. Set
When the image density is lower than a predetermined image density and the number of image formations is lower than a predetermined image formation number, the image density is lower than the predetermined image density and the number of image formations is The discharge amount is set to be smaller than when the number of times of image formation is higher than the predetermined number.
And wherein a call.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect,
  The preset period is 24 hours.

  According to a third aspect of the present invention, in the image forming apparatus according to the first aspect,
  The preset period is a pre-delimited time zone of one day.

  In order to solve the technical problem, an image forming apparatus according to a fourth aspect of the present invention provides:
  An image carrier,
  A latent image forming apparatus for forming a latent image on the surface of the image carrier;
  A developing device for developing the latent image on the surface of the image carrier into a visible image;
  A replenishing device for replenishing developer to the developing device;
  Discharge setting means for setting the amount of developer discharged from the developing device;
  A discharged image for forming a latent image on the surface of the image holding member, developing with the developing device, and discharging the developer in the developing device, according to the amount of developer discharged set by the discharge setting means. A discharge control means for the developer to be formed;
  With
  The discharge setting means includes a first image density during an image forming operation from a previous discharge amount setting to a current discharge amount setting, and a second image density calculated before the previous discharge amount setting. And set the developer discharge amount based on
  When the first image density is lower than a predetermined first determination value and the second image density is higher than a predetermined second determination value, the first image density is the first determination value. It is set so that less developer is discharged than when the second image density is lower than the determination value of 1 and the second image density is lower than the second determination value.
  It is characterized by that.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects,
  The discharge setting unit performs discharge setting when the number of continuous prints reaches a predetermined number or when the cumulative number of prints reaches a predetermined number.
  It is characterized by that.

According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects,
The development for setting the discharge image creation condition configured by at least one of the width, density, and frequency of the discharged image in the sub-scanning direction according to the developer discharge amount set by the discharge setting unit. Agent discharge control means,
It is provided with.

According to the first aspect of the present invention, when the image density and the number of image formations are low based on the image density from the previous discharge amount setting to the current discharge amount setting and the number of image formations, respectively. As compared with the case where the setting is not made so that the discharge amount is smaller than that when the toner is high, it is possible to reduce the excessive discharge of the developer while discharging the deteriorated developer.
According to the second aspect of the present invention, when the number of image formations in 24 hours is low, the discharge amount can be reduced.
According to the third aspect of the present invention, it is possible to set the discharge amount based on the number of times of image formation in a predetermined time zone of one day, and appropriately discharge amount according to the actual use of the image forming apparatus. Can be set.

According to the fourth aspect of the invention, based on the first image density and the second image density, when each image density is low, the discharge amount is smaller than when each image density is high. Compared to the case where the setting is not performed, excessive discharge of the developer can be reduced while discharging the deteriorated developer.
According to the fifth aspect of the present invention, it is possible to determine the timing for setting the discharge based on the continuous print number or the cumulative print number.
According to the invention of claim 6, the sub-scanning direction width of the discharge image, density, by at least one frequency, the discharge amount of the developer is Ru can be controlled.

FIG. 1 is an overall explanatory view of an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is an explanatory view of a visible image forming apparatus having an image carrier unit and a developing device. FIG. 3 is a functional diagram, so-called block diagram, of the control unit of the printer according to the first embodiment of the present invention. FIG. 4 is an explanatory diagram of an example of the discharged image according to the first embodiment. FIG. 5 is an explanatory diagram of a flowchart of the developer discharge control process according to the first embodiment. FIG. 6 is an explanatory diagram of a flowchart of the developer discharge setting process according to the first embodiment. FIG. 7 is a diagram corresponding to FIG. 3 of the first embodiment, and is a block diagram of the control unit of the printer of the second embodiment of the present invention. FIG. 8 is an explanatory diagram of a flowchart of the developer discharge control process according to the second embodiment, and corresponds to FIG. 5 according to the first embodiment. FIG. 9 is an explanatory diagram of a flowchart of developer discharge setting processing according to the second embodiment. FIG. 10 is a diagram corresponding to FIG. 3 of the first embodiment, and is a block diagram of a control unit of the printer of the third embodiment of the present invention. FIG. 11 is an explanatory diagram of a flowchart of developer discharge setting processing according to the third embodiment, and corresponds to FIG. 6 according to the first embodiment. FIG. 12 is a diagram corresponding to FIG. 7 of the second embodiment, and is a block diagram of the control unit of the printer of the fourth embodiment of the present invention. FIG. 13 is an explanatory diagram of a flowchart of the developer discharge control process of the fourth embodiment, and corresponds to FIG. 8 of the second embodiment. FIG. 14 is an explanatory diagram of a flowchart of developer discharge setting processing according to the fourth embodiment, and corresponds to FIG. 9 according to the second embodiment.

Next, specific examples of embodiments of the present invention (hereinafter referred to as examples) will be described with reference to the drawings, but the present invention is not limited to the following examples.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, the up-down direction is the Z-axis direction, and arrows X, -X, Y, -Y, The direction indicated by Z and -Z or the indicated side is defined as the front side, the rear side, the right side, the left side, the upper side, the lower side, or the front side, the rear side, the right side, the left side, the upper side, and the lower side, respectively.
In the figure, “•” in “○” means an arrow heading from the back of the page to the front, and “×” in “○” is the front of the page. It means an arrow pointing from the back to the back.
In the following description using the drawings, illustrations other than members necessary for the description are omitted as appropriate for easy understanding.

FIG. 1 is an overall explanatory view of an image forming apparatus according to Embodiment 1 of the present invention.
In FIG. 1, an image forming apparatus U is an example of a user interface UI as an example of an operation unit, an image input device U1 as an example of an image reading unit, a sheet feeding device U2, and an image forming apparatus main body. As an example, an image recording apparatus U3 and a sheet processing apparatus U4 are provided.

The user interface UI includes an input key such as a copy start key and a numeric keypad as an example of an input unit, and a display unit UI1.
The image input device U1 includes an image scanner as an example of an image reading device. In FIG. 1, an image input device U1 reads a document (not shown), converts it into image information, and inputs it to an image recording device U3.
The sheet feeding device U2 includes sheet feeding trays TR1 to TR4 as an example of a plurality of sheet feeding units, and a sheet feeding path through which a recording sheet S as an example of a medium accommodated in each of the sheet feeding trays TR1 to TR4 is conveyed. SH1 etc.

In FIG. 1, an image recording device U3 includes an image recording unit that records an image on the recording paper S conveyed from the paper supply device U2, a toner dispenser device U3a as an example of a replenishing device, a paper conveyance path SH2, and a paper discharge A path SH3, a sheet reversing path SH4, a sheet circulation path SH6, and the like are included. The image recording unit will be described later.
The image recording device U3 includes a control unit C, a laser drive circuit D as an example of a drive circuit of a latent image writing device controlled by the control unit C, and a power supply circuit E controlled by the control unit C. Etc. The laser drive circuit D, the operation of which is controlled by the control unit C, in advance receives a laser drive signal corresponding to image information of Y: yellow, M: magenta, C: cyan, K: black input from the image input device U1. At the set time, the image is output to the latent image forming apparatuses ROSy, ROSm, ROSc, and ROSk of each color.
Below the latent image forming devices ROSy, ROSm, ROSc, and ROSK of the respective colors, a drawing position in which a drawing member U3b for the image forming unit is drawn to the front of the image recording device U3 by a pair of left and right guide members R1 and R1. And a mounting position mounted inside the image recording apparatus U3.

FIG. 2 is an explanatory view of a visible image forming apparatus having an image carrier unit and a developing device.
1 and 2, a black image carrier unit UK includes a photosensitive member Pk as an example of an image carrier, a charger CCk as an example of a discharger, and a cleaner for an image carrier. A photoconductor cleaner CLk. In the first embodiment, the charger CCk is configured by a charging unit that can be attached to and detached from the image recording apparatus U3. Further, the image holding units UY, UM, and UC of other colors Y, M, and C are also charged with photoreceptors Py, Pm, and Pc, chargers CCy, CCm, and CCc as examples of a discharger, and photoreceptor cleaners CLy and CLm. , CLc. In Example 1, the K photoconductor Pk, which is frequently used and has a lot of surface wear, has a larger diameter than the other photoconductors Py, Pm, and Pc, and is capable of high-speed rotation and has a long service life. Has been changed.

Developing devices Gy to Gk are arranged on the right side of the image carrier units UY to UK. Each of the developing devices Gy to Gk is arranged to face the developing container G1 in which the developer is accommodated and the photosensitive members Py to Pk, and rotates and holds the developer in the developing container G1 on the surface. A developing roll R0 as an example of a developer holding body that forms a latent image on the surface of the bodies Py to Pk. In addition, a pair of agitating members G2 and G3 that circulate and convey in the front-rear direction while agitating the developer accommodated therein by rotating are accommodated inside the developing container G1.
Each of the image carrier units UY, UM, UC, UK and developing devices Gy, Gm, Gc, Gk having a developing roll R0 constitute toner image forming members UY + Gy, UM + Gm, UC + Gc, UK + Gk. The image holding unit UY, UM, UC, UK and developing devices Gy, Gm, Gc, Gk are detachably mounted on the drawing member U3b for the image forming unit.

In FIG. 1, the photosensitive members Py, Pm, Pc, and Pk are charged by the chargers CCy, CCm, CCc, and CCk, respectively, and then the latent image writing output from the latent image forming devices ROSy, ROSm, ROSc, and ROSk. An electrostatic latent image is formed on the surface by laser beams Ly, Lm, Lc, and Lk as an example of light. The electrostatic latent images on the surfaces of the photoreceptors Py, Pm, Pc, and Pk are converted into Y (yellow), M (magenta), C (cyan), and K (black) colors by the developing devices Gy, Gm, Gc, and Gk. The toner image is developed.
When development is performed in the developing devices Gy to Gk and the developer in the developing devices Gy to Gk is consumed, the toner dispenser device U3a disposed on the upper part of the image recording device U3 is operated, and the developer container As an example, the developer is replenished from the toner cartridges Ky, Km, Kc, and Kk according to the consumption amount.

The toner images on the surfaces of the photoreceptors Py, Pm, Pc, and Pk are an example of an image carrier and an example of an intermediate transfer member by primary transfer rolls T1y, T1m, T1c, and T1k as an example of a primary transfer unit. Are sequentially transferred onto the intermediate transfer belt B, and a multicolor image, that is, a so-called color image is formed on the intermediate transfer belt B. The color image formed on the intermediate transfer belt B is conveyed to a secondary transfer area Q4 as an example of an image recording position.
In the case of only black image data, only the K (black) photosensitive member Pk and the developing device Gk are used, and only a black toner image is formed.

In the image forming apparatus U according to the first exemplary embodiment, the rotational direction of the intermediate transfer belt B, between the primary transfer region of the most downstream K color and the secondary transfer region Q 4 are, the intermediate transfer belt B An image density sensor SN1 as an example of a density detection member capable of detecting the density of an image held on the surface of the image sensor is disposed.
After the primary transfer, the residual toner on the photosensitive member Py, Pm, Pc, Pk surface is cleaned photoconductor cleaners CLy, CLm, CLc, by CLk.

Below the drawing member U3b for the image forming unit, there is a space between a drawing position where the drawing member U3c for the intermediate transfer member is drawn to the front of the image recording apparatus U3 and a mounting position where the drawing member U3c is mounted inside the image recording apparatus U3. It is supported so that it can move. In the intermediate transfer member U3c, a belt module BM, which is an example of an intermediate transfer device, is in a raised position in contact with the lower surface of the photoreceptors Py, Pm, Pc, and Pk, and is lowered downward from the lower surface. It is supported so that it can move up and down between positions.
The belt module BM includes the intermediate transfer belt B, belt support rolls Rd, Rt, Rw, Rf, T2a as an example of an intermediate transfer member support member, and the primary transfer rolls T1y, T1m, T1c, T1k. Have. Belt support rolls Rd, Rt, Rw, Rf, and T2a include a belt drive roll Rd as an example of a drive member, a tension roll Rt as an example of a tension applying member, a walking roll Rw as an example of a meandering prevention member, and a driven member having a backup roll T2a as an example of a facing member of the plurality of idler rolls Rf and the secondary transfer region Q4 as an example. The intermediate transfer belt B is supported by the belt support rolls Rd, Rt, Rw, Rf, T2a so as to be rotatable in the direction of the arrow Ya.

A secondary transfer unit Ut is disposed below the backup roll T2a. The secondary transfer unit Ut has a secondary transfer roll T2b as an example of a secondary transfer member. The secondary transfer roll T2b is disposed so as to be separated from and contactable with the backup roll T2a with the intermediate transfer belt B interposed therebetween. The secondary transfer area Q4 depends on the area where the secondary transfer roll T2b contacts the intermediate transfer belt B. Is formed. Further, a contact roll T2c as an example of a contact member for applying voltage is in contact with the backup roll T2a, and a secondary transfer device T2 is constituted by the rolls T2a to T2c.
A secondary transfer voltage having the same polarity as the charging polarity of the toner is applied to the contact roll T2c at a preset time from the power supply circuit controlled by the control unit C.

A sheet conveyance path SH2 is disposed below the belt module BM. The recording sheet S fed from the sheet feeding path SH1 of the sheet feeding device U2 is conveyed to the sheet conveying path SH2, and a toner image is transferred to a secondary transfer area by a registration roll Rr as an example of a sheet feeding timing adjusting member. At the same time as being conveyed to Q4, it is conveyed to the secondary transfer region Q4 through the medium guide members SGr and SG1 before transfer.
The toner image on the intermediate transfer belt B is transferred to the recording paper S by the secondary transfer device T2 when passing through the secondary transfer region Q4. In the case of a full-color image, the toner images primarily transferred onto the surface of the intermediate transfer belt B are secondarily transferred onto the recording paper S all at once.

The intermediate transfer belt B after the secondary transfer is cleaned, that is, cleaned by a belt cleaner CLB as an example of a cleaner for the intermediate transfer member.
The primary transfer rolls T1y, T1m, T1c, T1k, the intermediate transfer belt B, 2 transfer unit T2, by a belt cleaner CLB, etc., the transfer device T1 + B + T2 + CLB for transferring an image of the photoreceptor Py~Pk surface the recording paper S configuration Has been.

The recording sheet S on which the toner image is secondarily transferred is conveyed to the fixing device F through a medium guide member SG2 after transfer and a sheet conveyance belt BH as an example of a medium conveyance member before fixing. The fixing device F has a heating roll Fh as an example of a heat fixing member and a pressure roll Fp as an example of a pressure fixing member, and is fixed by a region where the heating roll Fh and the pressure roll Fp are in contact with each other. Region Q5 is formed.
The toner image on the recording paper S is heated and fixed by the fixing device F when passing through the fixing region Q5.
The toner image forming members UY + Gy, UM + Gm, UC + Gc, UK + Gk, the transfer device T1 + B + T2 + CLB, the fixing device, and the like constitute the image recording unit of Example 1 for recording an image on the recording paper S.

A first gate GT1 as an example of a conveyance path switching member is provided on the downstream side of the fixing device F. The first gate GT1 selectively switches the recording sheet S conveyed through the sheet conveyance path SH2 and heated and fixed in the fixing region Q5 to either the sheet discharge path SH3 or the sheet reversing path SH4 of the sheet processing apparatus U4. . The recording sheet S conveyed to the sheet discharge path SH3 is conveyed to the sheet conveyance path SH5 of the sheet processing apparatus U4.

A curl correction device U4a, which is an example of a curvature correction device, is disposed in the middle of the paper transport path SH5, and a second gate G4, which is an example of a transport path switching member, is disposed on the paper transport path SH5. ing. The second gate G4 is a recording sheet S conveyed from the sheet conveying path SH 5 of the image recording apparatus U3, curved, so-called, in accordance with the direction of the curl, the first curl correcting member h1 or the second curl correcting member Transport to either side of h2. The recording paper S conveyed to the first curl correction member h1 or the second curl correction member h2 is curled when passing. The recording sheet S with the curl corrected is in a so-called face-up state in which the image fixing surface of the sheet faces upward from a discharge roll Rh as an example of a discharge member to a discharge tray TH1 as an example of a discharge unit of the paper processing device U4. It is discharged at.

The recording sheet S conveyed to the sheet reversing path SH4 side of the image recording apparatus U3 by the first gate GT1 passes in such a manner as to push the so-called mylar gate GT2 in the conveying direction constituted by an elastic thin film member. Then, it is conveyed to the sheet reversing path SH4 of the image recording apparatus U3.
A sheet circulation path SH6 and a sheet reversing path SH7 are connected to the downstream end of the sheet reversing path SH4 of the image recording apparatus U3, and a mylar gate GT3 is also disposed at the connecting portion. The sheet conveyed through the first gate GT1 to the sheet reversing path SH4 passes through the Mylar gate GT3 and is conveyed to the sheet reversing path SH7 side of the sheet processing apparatus U4. When performing duplex printing, the recording paper S that has been transported through the paper reversing path SH4 passes through the Mylar gate GT3, is transported to the paper reversing path SH7, and then transported in the reverse direction, so-called switchback. Then, the conveyance direction is regulated by the mylar gate GT3, and the recording sheet S that has been switched back is conveyed to the sheet circulation path SH6 side. The recording sheet S conveyed to the sheet circulation path SH6 is retransmitted to the secondary transfer area Q4 through the sheet feeding path SH1.

On the other hand, when the recording paper S conveyed on the paper reversing path SH4 is switched back after the trailing edge of the recording paper S passes through the Mylar gate GT2 and before passing through the Mylar gate GT3, the Mylar gate GT2 causes the recording paper S The transport direction is regulated, and the recording paper S is transported to the paper transport path SH5 with the front and back sides reversed. Recording sheet S sides are inverted, after the curl is corrected by the curl correcting member U4a, the emissions tray TH1 of the sheet processing apparatus U4, the image fixing surface of the recording paper S is facing downward, so-called, face-down It can be discharged in a state.
A sheet transport path SH is constituted by the elements indicated by the symbols SH1 to SH7. Further, the sheet conveying device SU is constituted by the elements indicated by the symbols SH, Ra, Rr, Rh, SGr, SG1, SG2, BH, GT1 to GT3.

(Description of the control part of Example 1)
FIG. 3 is a functional diagram, so-called block diagram, of the control unit of the printer according to the first embodiment of the present invention.
In FIG. 3, the control unit C includes an input / output interface I / O for inputting / outputting signals from / to the outside, a ROM storing a program and information for performing necessary processing, a read-only memory, a necessary RAM for temporarily storing data: Random access memory; CPU for performing processing according to the program stored in the ROM: Central processing unit; Small information processing apparatus having an oscillator, etc., so-called microcomputer Therefore, various functions can be realized by executing a program stored in the ROM.

(Signal output element connected to control unit C)
The control unit C receives an output signal from a signal output element such as a user interface UI or an image density sensor SN1.
The user interface UI includes a display unit UI1, a power button UI2, a copy start key UI3 and a numeric keypad UI4 as examples of input buttons.
The image density sensor SN1 detects the density of the image on the surface of the intermediate transfer belt B.

(Controlled element connected to control unit C)
The control unit C is connected to the main drive source drive circuit D1, the power supply circuit E, and other control elements (not shown), and outputs their operation control signals.
The main drive source drive circuit D1 rotationally drives the photoreceptors Py to Pk, the intermediate transfer belt B, and the like via the main drive source M1.
The power supply circuit E includes a development power supply circuit Ea, a charging power supply circuit Eb, a transfer power supply circuit Ec, a fixing power supply circuit Ed, and the like.

The developing power supply circuit Ea applies a developing voltage to the developing roll R0 of the developing devices Gy to Gk.
The charging power supply circuit Eb applies a charging voltage for charging the surfaces of the photoreceptors Py to Pk to the chargers CCy to CCk, respectively.
The transfer power supply circuit Ec applies a transfer voltage to the primary transfer rolls T1y to T1k and the secondary transfer roll T2b.
The fixing power supply circuit Ed supplies a heater heating power to the heating roll Fh of the fixing device F.

(Function of control unit C)
The control unit C has a function of executing processing according to an input signal from the signal output element and outputting a control signal to each control element. That is, the control unit C has the following functions.
C1: Image forming operation control means The image forming operation control means C1 controls the drive of each member of the image forming apparatus U, the application timing of each voltage, etc. according to the image information input from the image input apparatus U1, A job as an example of an image forming operation is executed.
C2: Main drive source control means The main drive source control means C2 controls the drive of the main drive source M1 via the main drive source drive circuit D1, and controls the drive of the photoreceptors Py to Pk and the like.

C3: Power supply circuit control means The power supply circuit control means C3 includes a development power supply circuit control means C3A, a charging power supply circuit control means C3B, a transfer power supply circuit control means C3C, and a fixing power supply circuit control means C3D. Then, the operation of the power supply circuit E is controlled to control voltage application and power supply to each member.
C3A: Developing power circuit control means The developing power circuit control means C3A controls the developing power circuit Ea to control the developing voltage applied to the developing rolls of the developing devices Gy to Gk.
C3B: Charging power supply circuit control means The charging power supply circuit control means C3B controls the charging power supply circuit Eb to control the charging voltage applied to the chargers CCy to CCk.

C3C: Transfer power supply circuit control means The transfer power supply circuit control means C3C controls the transfer power supply circuit Ec to apply to the primary transfer roll T1y to T1k and to the secondary transfer roll T2b. The secondary transfer voltage is controlled.
C3D: Fixing power supply circuit control means The fixing power supply circuit control means C3D controls the temperature of the heater of the heating roll Fh of the fixing device F, that is, controls the fixing temperature, by controlling the fixing power supply circuit Ed.

C4: Latent image formation control means The latent image formation control means C4 controls the latent image forming devices ROSy to ROSk, respectively, so that the latent images of each color of Y, M, C, K are transferred to the surface of the photoreceptors Py to Pk of each color. To form.
C5: Replenishment Control Unit The replenishment control unit C5 controls the developer replenishment by operating the toner dispenser device U3a for a time corresponding to the developer consumption amount of the developing devices Gy to Gk.
C6: Continuous Print Number Counting Unit The continuous print number counting unit C6 counts the continuous print number N1, which is the number of continuously printed sheets, when a job as an example of an image forming operation is executed. Note that the continuous printing number counting means C6 of the first embodiment counts the number of printed sheets N1 by converting the number of printed sheets of the recording paper S into the size of A4.

C7: Pixel Number Counting Unit The pixel number counting unit C7 counts the number of pixels M1 of the image written by the latent image forming devices ROSy to ROSk for each color of Y, M, C, and K during the job.
C8: Cumulative Printed Number Counting Unit The cumulative printed number counting unit C8 counts the cumulative number of printed sheets N2, which is the cumulative number of sheets printed by the job. Note that the cumulative printed number counting means C8 of the first embodiment counts the cumulative printed number N2 since the developer discharging operation from the previous developing devices Gy to Gk was performed.

C9: Developer Discharge Control Unit The developer discharge control unit C9 includes a first period determination unit C9A, a discharge setting unit C9B, and a band forming unit C9C as an example of a discharge image forming unit. A latent image is formed on the surface of each of the photoreceptors Py to Pk, and development is performed by the developing devices Gy to Gk to form a toner band as an example of a discharged image that discharges the developer in the developing devices Gy to Gk. The developer discharge control unit C9 according to the first exemplary embodiment is configured such that the image density AC1 at the time of the job in the first period set in advance is a period different from the first period and in the second period set in advance. Based on the developer consumption tendency at the time of the job, when the developer consumption tends to be large, the toner band creation conditions are set so that the developer to be discharged is reduced.

C9A: First period determination means The first period determination means C9A has a band creation determination value storage means C9A1 and a discharge timing determination means C9A2, and whether or not the first period has elapsed. Is determined. The first period determination unit C9A according to the first exemplary embodiment uses the continuous printing number N1 as an example of the number of image formations or the cumulative number of printings N2 as an example of the first period. It is determined whether or not the band creation interval has elapsed.

C9A1: Band creation discriminant value storage means The band creation discriminant value storage means C9A1 discriminates whether or not it is time to create a toner band, that is, whether or not the first period has elapsed. The discrimination values Na and Nb are stored. The discriminating value storage means C9A1 according to the first embodiment creates a first band creation discriminating value Na that is a discriminating value for the continuous printing number N1 and a second band creation that is a discriminating value for the cumulative printing number N2. The discrimination value Nb is stored. In the first embodiment, the first band creation determination value Na is set to Na = 20 [sheets] as an example, and the second band creation determination value Nb is set to Nb = 50 [sheets] as an example. Is set. In addition, each numerical value is not limited to the illustrated numerical value, and can be arbitrarily changed according to a design, a specification, etc., and each discrimination value Na and Nb can also be made into the same numerical value.

C9A2: Discharge Timing Determination Unit The discharge timing determination unit C9A2 determines whether it is time to perform a discharging operation for creating a toner band and discharging the developer from the developing devices Gy to Gk. The discharge timing determination unit C9A2 according to the first exemplary embodiment is configured such that the continuous print number N1 is equal to or greater than the first band creation determination value Na or the cumulative print number N2 is equal to or greater than the second band creation determination value Nb. Then, it is determined that it is time to execute the discharge operation, that is, the first period has elapsed.

FIG. 4 is an explanatory diagram of an example of the discharged image according to the first embodiment.
C9B: Discharge Setting Unit The discharge setting unit C9B includes a previous average image density storage unit C9B1, an average image density calculation unit C9B2, a current average image density storage unit C9B3, and a current low density discrimination value storage. Means C9B4, first period deterioration determination means C9B5, previous high density determination value storage means C9B6, previous low density determination value storage means C9B7, second period deterioration determination means C9B8, bandwidth Setting means C9B9, and the amount of the developer discharged from the developing devices Gy to Gk is set for each color of Y, M, C, and K. In FIG. 4, the discharge setting means C9B of Embodiment 1 sets the width L in the sub-scanning direction of the toner band 1 formed according to the amount of developer discharged for each color of Y, M, C, and K. Set.

C9B1: Previous Average Image Density Storage Unit The previous average image density storage unit C9B1 uses the average image density calculated when the previous discharge operation is performed as an example of the consumption trend of the second period. Is stored as the previous average image density AC0.
C9B2: Average Image Density Calculation Unit The average image density calculation unit C9B2 calculates the average image density AC1 based on the counted number of pixels M1 and the period in which the number of pixels M1 is counted. The average image density calculating unit C9B2 according to the first exemplary embodiment calculates the total number of pixels in all corresponding image areas from either the number of printed sheets N1 or N2 determined by the discharge time determining unit C9A2 and the size of A4. The average image density AC1, which is the ratio of the number of written pixels M1 to the number, is calculated.

C9B3: Current Average Image Density Storage Unit The current average image density storage unit C9B3 uses the average image density calculated by the average image density calculation unit C9B2 as an example of the average image density in the first period. Is stored as an average image density AC1.
C9B4: Current Low Density Discriminant Value Storage Unit The current low density discriminant value storage unit C9B4 stores the current low density discriminant value ACa for determining whether or not the current average image density AC1 is low. . In the first embodiment, the current low density determination value ACa is set to ACa = 3 [%] as an example.

C9B5: First Period Deterioration Determination Unit The first period deterioration determination unit C9B5 is configured so that the developer in the developing devices Gy to Gk is supplied during the period from the previous discharge operation to the current discharge operation as an example of the first period. It is determined whether or not it has deteriorated. In the first period, the deterioration determining unit C9B5 of the first embodiment has a small consumption amount of developer in the developing devices Gy to Gk when the average image density AC1 is equal to or lower than the low density determination value ACa in the first period. In this case, it is determined that there is a high possibility that the developer is agitated by the agitating members G2 and G3 and deteriorated with almost no developer used. On the other hand, when the average image density AC1 is larger than the low density discrimination value ACa, that is, when the consumption amount of the developer is large, new developer is supplied from the toner cartridges Ky to Kk, and the development deteriorated as a whole. It is determined that the possibility of containing the agent is low.
C9B6: Previous High Density Discriminant Value Storage Unit The previous high density discriminant value storage unit C9B6 obtains the previous high density discriminant value ACb for discriminating whether or not the previous average image density AC0 is high. Remember. In the first embodiment, the previous high-density discrimination value ACb is set to ACb = 10 [%] as an example.

C9B7: Previous Low Density Discriminant Value Storage Unit The previous low density discriminant value storage unit C9B7 uses the previous low density discriminant value ACc for discriminating whether or not the previous average image density AC0 is low. Remember. In the first embodiment, the previous low density determination value ACc is set to ACc = 3 [%] as an example.
C9B8: Second Period Deterioration Determination Means The second period deterioration determination means C9B8 is an example of the second period in which the developer in the developing devices Gy to Gk is supplied during the period from the previous discharge operation to the previous discharge operation. It is determined whether or not it has deteriorated. In the second period, the deterioration determining means C9B8 of the first embodiment uses the stirring members G2 and G3 when the developer consumption in the developing devices Gy to Gk is small in the second period, with almost no developer used. When the developer consumption is large, it is determined that the developer is agitated in step S3 and a new developer is replenished from the toner cartridges Ky to Kk. Is determined to be low.

C9B9: Bandwidth setting means Bandwidth setting means C9B9 as an example of a developer discharge amount setting means sets the developer discharge amount in accordance with the degree of developer deterioration. The band width setting unit C9B9 according to the first exemplary embodiment sets the developer discharge amount by setting the width L in the sub-scanning direction of the toner band 1 that is a discharge image. The bandwidth setting unit C9B9 according to the first exemplary embodiment consumes a large amount of developer when the average image density AC1 is high, that is, when AC1 ≧ ACa from the previous discharge operation in the first period. Judging that the deterioration is small, the width L of the toner band is set to L = 0, that is, the toner band 1 is not formed. Further, when the previous average image density AC0 is high from the previous time when the current average image density AC1 is low density and the second period, that is, when AC1 <ACa and AC0 ≧ ACb, the previous time from the previous time. In the meantime, it is determined that the developer is sufficiently consumed, the overall consumption tendency is large, and the deterioration is small as a whole, and the width L = 0 of the toner band 1 is set.

  Further, when the current average image density AC1 is low density and the previous average image density AC0 is medium density, that is, when AC1 <ACa and ACc ≦ AC0 <ACb, the overall consumption tendency is moderate. Therefore, it is determined that the deterioration is moderate, and the width L of the toner band 1 is set to the first band width L1. In the first embodiment, the first bandwidth L1 is set to L1 = 20 [mm] as an example. Further, when the current average image density AC1 is low and the previous average image density AC0 is also low, that is, when AC1 <ACa and AC0 <ACc, the overall consumption tendency is small and the deterioration progresses. Therefore, the width L of the toner band 1 is set to the second band width L2. In the first embodiment, the second bandwidth L2 is set to L2 = 50 [mm] as an example. In the first exemplary embodiment, the density of the toner band 1 is set to a density of 80% as an example, and the length of the toner band 1 in the main scanning direction is set to the maximum length.

C9C: Band Forming Unit A band forming unit C9C as an example of a discharged image forming unit transfers the toner band 1 corresponding to the width L set by the discharge setting unit C9B via the latent image formation control unit C4. To form Pk.
C10: Density Adjustment Unit The density adjustment unit C10 is a pattern image based on the detection result of the density pattern creation unit C10A as an example of a unit for creating the pattern image 2 as an example of an image for density detection and the image density sensor SN1. Pattern density detecting means C10B as an example of means for detecting the density of 2 and adjusting the density of the formed toner image. The density adjusting unit C10 of the first embodiment forms, develops, and primarily transfers a pattern image having a preset density, that is, a so-called patch image 2, reads the actual density with the image density sensor SN1, and sets the preset density and The density is adjusted based on the difference from the actual density. The density adjustment by the density adjusting means C10, so-called process control, is a well-known and commonly used technique, and various conventionally known configurations can be adopted, and detailed description thereof is omitted.

(Explanation of flowchart of Example 1)
Next, the flow of control in the image forming apparatus U according to the first embodiment will be described with reference to a flowchart, a so-called flowchart.
(Description of flowchart of developer discharge control process)
FIG. 5 is an explanatory diagram of a flowchart of the developer discharge control process according to the first embodiment.
5 is performed according to a program stored in the control unit C of the image forming apparatus U. This process is executed in parallel with other various processes of the image forming apparatus U.
The flowchart shown in FIG. 5 is started when the image forming apparatus U is powered on.

In ST1 of FIG. 5, it is determined whether or not the job has been started. If yes (Y), the process proceeds to ST2. If no (N), ST1 is repeated.
In ST2, the continuous print number N1 is initialized. That is, N1 = 0 is set. Then, the process proceeds to ST3.
In ST3, the following processes (1) and (2) are executed, and the process proceeds to ST4.
(1) An image forming operation, that is, a job is executed.
(2) Count the number of pixels M1.
In ST4, 1 is added to the continuous print number N1. That is, N1 = N1 + 1 is executed. Then, the process proceeds to ST5.

In ST5, it is determined whether or not the continuous print number N1 is equal to or greater than the first band creation determination value Na. If yes (Y), the process proceeds to ST6. If no (N), the process proceeds to ST9.
In ST6, a discharge setting process for setting the amount of developer discharged from the developing devices Gy to Gk described later in a subroutine in FIG. 6 is executed, and the process proceeds to ST7.
In ST7, the following processes (1) to (3) are executed, and the process proceeds to ST8.
(1) The toner band 1 corresponding to the discharge setting process is formed.
(2) Depending on the amount of developer consumed by forming the toner band 1, the toner dispenser device U3a operates to replenish the developer.
(3) The continuous print number N1 and the cumulative print number N2 are initialized. That is, N1 = N2 = 0.

In ST8, a pattern image 2 for detecting the image density is formed, and density detection and density adjustment by the image density sensor SN1 are performed. Then, the process proceeds to ST9.
In ST9, it is determined whether or not the job is finished. If yes (Y), the process proceeds to ST10. If no (N), the process returns to ST3.
In ST10, the continuous print number N1 is added to the cumulative print number N2. That is, N2 = N2 + N1. Then, the process proceeds to ST11.
In ST11, it is determined whether or not the cumulative number of printed sheets N2 is equal to or greater than the second band creation determination value Nb. If yes (Y), the process proceeds to ST12. If no (N), the process returns to ST1.

In ST12, a discharge setting process for setting the amount of developer discharged from the developing devices Gy to Gk described later in FIG. 6 is executed, and the process proceeds to ST13.
In ST13, the following processes (1) to (3) are executed, and the process proceeds to ST14.
(1) The toner band 1 corresponding to the discharge setting process is formed.
(2) Depending on the amount of developer consumed by forming the toner band 1, the toner dispenser device U3a operates to replenish the developer.
(3) The accumulated print number N2 is initialized. That is, N2 = 0.
In ST14, a pattern image 2 for detecting the image density is formed, and density detection and density adjustment by the image density sensor SN1 are performed. Then, the process returns to ST1.

(Description of flowchart of discharge setting process)
FIG. 6 is an explanatory diagram of a flowchart of the developer discharge setting process according to the first embodiment.
In ST21 of FIG. 6, the current average image density AC1 stored is stored as the previous average image density AC0. Then, the process proceeds to ST22.
In ST22, the current average image density AC1 is calculated from the number of pixels M1. Then, the process proceeds to ST23.
In ST23, it is determined whether or not the current average image density AC1 is equal to or higher than the current low density determination value ACa. If yes (Y), the process proceeds to ST24, and, if no (N), the process proceeds to ST25.
In ST24, the width L of the toner band 1 is set to L = 0. Then, the discharge setting process in FIG. 6 ends.

In ST25, it is determined whether or not the previous average image density AC0 is equal to or higher than the previous high density determination value ACb. If yes (Y), the process returns to ST24, and if no (N), the process proceeds to ST26.
In ST26, it is determined whether or not the previous average image density AC0 is equal to or higher than the previous low density determination value ACc. If yes (Y), the process proceeds to ST27, and, if no (N), the process proceeds to ST28.
In ST27, the width L of the toner band 1 is set to L = L1. Then, the discharge setting process in FIG. 6 ends.
In ST28, the width L of the toner band 1 is set to L = L2. Then, the discharge setting process in FIG. 6 ends.

(Operation of Example 1)
In the image forming apparatus U according to Embodiment 1 of the present invention having the above-described configuration, when a job that is an image forming operation is started, the developer is consumed along with the image forming operation. When the continuous print number N1 or the cumulative print number N2 is equal to or greater than the discrimination values Na and Nb, processing for discharging the deteriorated developer in the developing devices Gy to Gk is performed. In the first embodiment, the average image density AC1 according to the most recent use state of the image forming apparatus U from the previous discharge operation to the current discharge operation and the average image density AC0 from the previous time to the previous time are relatively long. The developer discharge amount is set in accordance with the usage status of the image forming apparatus U over the range.

In the conventional configurations described in Patent Documents 1 and 2, it is determined whether or not to discharge the developer depending on whether or not the average image density in the most recent period from the previous time to the current time is low. Even when a high-density image is printed between the previous time and the previous time, the developer is consumed and replenished in the developing devices Gy to Gk, that is, the developer is sufficiently replaced, and the deterioration has not progressed so much. If the latest average image density is low, the developer is discharged, and there is a problem that wasteful discharge is performed. In addition, when wasteful discharge is performed, there arises a problem that the collection container for collecting the discharged developer is quickly filled and must be frequently replaced.
On the other hand, in the first embodiment, even when the latest average image density AC1 is low, the deterioration is advanced when the consumption amount is small due to the long-term consumption tendency including the previous time to the previous time. When the toner band 1 having the maximum width L2 is formed and the consumption amount is medium, it is determined that the progress of deterioration is also medium, and the toner band 1 having the short width L1 is formed. When the amount of consumption is large, it is determined that the deterioration has progressed and the toner band 1 is not formed. Therefore, as compared with the conventional configuration, wasteful developer discharge is reduced, and it is possible to prevent the collection container from being replaced frequently.

In the first exemplary embodiment, whether or not the toner band 1 is formed when N1 ≧ Na is satisfied with respect to the first band creation determination value Na that is smaller than the second band creation determination value Nb. Is being determined. That is, when the number of continuous prints increases, the temperature rises with the driving of each member in the image recording apparatus U3, such as rotation and discharge, and the image recording apparatus U3 is cooled in the middle while being cooled. As compared with the above, the developer is likely to deteriorate. Therefore, the deteriorated developer can be discharged more quickly than in the case where the band creation determination values Na and Nb are the same. In other words, when the cooling is performed after a long time, the frequent discharge of the developer is reduced.
Further, in the first exemplary embodiment, density adjustment, so-called process control is performed after the developer discharging operation, and the process control is performed before the discharging operation that may include the deteriorated developer. In comparison, the accuracy of density adjustment is improved.

Next, the image forming apparatus U according to the second embodiment of the present invention will be described. In the description of the second embodiment, components corresponding to the components of the first embodiment are denoted by the same reference numerals, and Detailed description is omitted. The second embodiment is different from the first embodiment in the following points, but is configured in the same manner as the first embodiment in other points.

(Description of the control part C of Example 2)
FIG. 7 is a diagram corresponding to FIG. 3 of the first embodiment, and is a block diagram of the control unit of the printer of the second embodiment of the present invention.
In FIG. 7, the control unit C of the image forming apparatus U according to the second embodiment has a discharge setting unit C9B ′ instead of the discharge setting unit C9B ′ in the control unit C of the image forming apparatus U according to the first embodiment. A means C11, a print mode acquisition means C12, and a print number storage means C13 are added.

(Function of control unit C)
C11: Time acquisition means The time acquisition means C11 acquires the current time measured by the clock TM1.
C12: Print Mode Acquisition Unit The print mode acquisition unit C12 acquires a print mode as an example of a printing operation of an image recorded by the image recording device U3. The print mode acquisition unit C12 according to the second embodiment acquires whether the image is a monochrome image or a multicolor image, that is, whether printing is performed in the monochrome mode or whether printing is performed in the full color mode.
C13: Printed Number Storage Unit The printed number storage unit C13 stores, for each job, the time when the job is executed and the print mode, and the continuous printed number N1 in association with each other.

C9B ': Discharge setting means The discharge setting means C9B' includes an average image density calculation means C9B2, an integrated number calculation means C14, a high frequency discrimination number storage means C15, and a low frequency discrimination number storage means C16, A second period deterioration determining means C17; a current low density determination value storage means C9B4 '; a first period deterioration determining means C9B5'; and a bandwidth setting means C9B9 '; The amount of developer discharged from ~ Gk is set for each color of Y, M, C, and K.
C14: Accumulated number calculating means The accumulated number calculating means C14 is an example of the second period based on the information stored in the printed sheet number storing means C13. An accumulated sheet number N4 obtained by accumulating the number of printed sheets is calculated for each color. Therefore, in the case of Y, M, and C, an integrated number N4 is calculated by integrating the number of printed sheets in the full color mode. In the case of K, the integrated number of sheets in the monochrome mode is integrated with the number of printed sheets in the full color mode. Accumulate N4. In the first embodiment, the time at which the job is executed is stored and the cumulative number N4 of jobs executed within a period of 24 hours is calculated. However, the present invention is not limited to this. It is also possible to make the period longer or shorter than 24 hours. Further, the time is not stored in association with each other, but for example, 0:00 to 6:00 (time zone “1”), 6:00 to 12:00 (time zone “2”), 12:00 to 18:00 (time zone “3”). ”), 18:00 to 24:00 (time zone“ 4 ”), it is also possible to store the jobs performed for each time zone by dividing the time zone. When storing in time zones, the storage capacity can be reduced compared to storing the time itself.

C15: High Frequency Discrimination Number Storage Unit The high frequency discrimination number storage unit C15 stores a high frequency discrimination number Nd for determining whether the printing frequency in the second period is high. That is, the high-frequency discriminating number Nd is a threshold value for discriminating whether or not it is an extreme case where the replacement of the developer is frequently performed or hardly performed. In the second embodiment, Nd = 2000 [sheets] is stored as the high-frequency discrimination number Nd.
C16: Low Frequency Discrimination Number Storage Unit The low frequency discrimination number storage unit C16 stores a low frequency discrimination number Ne for determining whether or not the printing frequency in the second period is low. In the second embodiment, Nd = 100 [sheets] is stored as the low-frequency discrimination number Ne.

C17: Second Period Degradation Determination Unit The second period deterioration determination unit C17 determines the usage frequency of the developing devices Gy to Gk in the second period based on the integrated number N4 and the frequency determination number Nd, Ne. By determining, the consumption tendency of the developer in the developing devices Gy to Gk, that is, the deterioration tendency is determined. In the second embodiment, when N4 ≧ Nd, it is determined that the consumption tendency is extremely large. When Ne ≦ N4 <Nd, it is determined that the consumption tendency is medium. When N4 <Ne, the consumption tendency is determined. It is determined that there is little or almost no consumption.
C9B4 ′: Current Low Density Discriminant Value Storage Unit The current low density discriminant value storage unit C9B4 ′ stores the current low density discriminant value ACa for determining whether the current average image density AC1 is low. Store ACa '. In the second embodiment, the current low density discriminant value ACa for high frequency or medium frequency is set to ACa = 3 [%] as in the first embodiment, and the present low density discriminant value for low frequency is set. ACa ′ is set to ACa ′ = 2 [%].

C9B5 ′: first period deterioration determining means The first period deterioration determining means C9B5 ′ is an example of the first period, and the development in the developing devices Gy to Gk in the period from the previous discharging operation to the current discharging operation. It is determined whether or not the agent has deteriorated. The first period of deterioration determining means C9B5 Example 2 ', in the first period, if the consumption amount of the developer in the current image device Gy~Gk is small, most of the remains developer is not used agitator G2 , G3, it is determined that there is a high possibility that the developer is deteriorated, and when the developer consumption is large, a new developer is replenished from the toner cartridges Ky to Kk, and the developer is deteriorated as a whole. Is determined to be low.

C9B9 ': Bandwidth setting means Bandwidth setting means C9B9' as an example of a developer discharge amount setting means sets the developer discharge amount in accordance with the degree of developer deterioration. The band width setting unit C9B9 ′ according to the second exemplary embodiment sets the developer discharge amount by setting the width L in the sub-scanning direction of the toner band 1 that is a discharge image. The bandwidth setting unit C9B9 ′ of the second embodiment is configured to display an image when the integrated number N4 is equal to or greater than the high frequency determination number Nd and the current average image density AC1 is high, that is, when N4 ≧ Nd and AC1 ≧ ACa. The developer is frequently formed and the degree of deterioration of the developer is high, but it is determined that the replacement of the developer is large, and it is determined that the deterioration of the developer is small as a whole, and the width L of the toner band is set to L = 0. .
Further, when the cumulative number N4 is equal to or higher than the high-frequency discrimination number Nd and the current average image density AC1 is a low image density, that is, when N4 ≧ Nd and AC1 <ACa, the degree of deterioration of the developer with high frequency of image formation. In addition, it is determined that there is little change in the developer, and overall, it is determined that there is a high possibility that the deterioration of the developer is extremely advanced, and the width L of the toner band is changed to the third band width L3. Set. In the second embodiment, the third bandwidth is set to 100 [mm].

Further, when the integrated number N4 is less than the high frequency determination number Nd and equal to or more than the low frequency determination number Ne and the current average image density AC1 is high, that is, when Ne ≦ N4 <Nd and AC1 ≧ ACa, the image Although the formation is moderate and the degree of deterioration of the developer is moderate, it is determined that the developer is frequently replaced. As a whole, it is determined that the deterioration of the developer is small, and the width L of the toner band is set to L = 0. Set to.
Further, when the integrated number N4 is less than the high frequency determination number Nd and equal to or more than the low frequency determination number Ne and the current average image density AC1 is low, that is, when Ne ≦ N4 <Nd and AC1 <ACa, the image The width of the toner band is judged that the formation is moderate and the degree of deterioration of the developer is moderate, the change of the developer is small, and the possibility that the deterioration of the developer is progressing as a whole is high. L is set to the second bandwidth L2. Note that the second bandwidth L2 of the second embodiment is set to the same value as the second bandwidth L2 of the first embodiment.

Further, when the cumulative number N4 is less than the low frequency determination number Ne and the current average image density AC1 is high, that is, when Ne> N4 and AC1 ≧ ACa, the degree of deterioration of the developer is low in frequency. In addition, it is determined that there is much change in the developer, and as a whole, it is determined that there is little deterioration of the developer, and the width L of the toner band is set to L = 0.
Further, when the integrated number N4 is less than the low frequency determination number Ne and the current average image density AC1 is low, that is, when N4 <Ne and AC1 <ACa, the image formation is infrequent and the developer is deteriorated. Although the degree is small, it is determined that the replacement of the developer is small, and as a whole, it is determined that the deterioration of the developer is slightly advanced, and the width L of the toner band is set to the first band width L1. Note that the first bandwidth L1 of the second embodiment is set to the same value as the first bandwidth L1 of the first embodiment.

(Explanation of flowchart of Example 2)
Next, a control flow in the image forming apparatus U according to the second embodiment will be described with reference to a flowchart, that is, a so-called flowchart.
(Description of flowchart of developer discharge control process)
FIG. 8 is an explanatory diagram of a flowchart of the developer discharge control process according to the second embodiment, and corresponds to FIG. 5 according to the first embodiment.
In FIG. 8, in the developer discharge control process of the second embodiment, ST31 is executed between ST1 and ST2 with respect to the developer discharge control process of the first embodiment, and ST7 ′ is replaced with ST7 ′. And ST32 is executed instead of ST10, and only the contents of the discharge setting process subroutines of ST6 and ST12 are different, and the other processes are the same, so the same process is assigned the same ST number. Detailed description will be omitted.

In ST31 of FIG. 8, the following processes (1) and (2) are executed, and the process proceeds to ST2.
(1) Acquire the current time (2) Acquire the print mode.
Next, ST2 to ST6 are executed, and the process proceeds to ST7 '.
In ST7 ′, the following processes (1) to (4) are executed, and the process proceeds to ST8.
(1) The toner band 1 corresponding to the discharge setting process is formed.
(2) Depending on the amount of developer consumed by forming the toner band 1, the toner dispenser device U3a operates to replenish the developer.
(3) The continuous print number N1 is stored together with the current time and the print mode.
(4) The continuous print number N1 and the cumulative print number N2 are initialized. That is, N1 = N2 = 0.
Next, the processing of ST8 to ST9 is executed, and if yes (Y) in ST9, the process proceeds to ST32.
In ST32, the following processes (1) and (2) are executed, and the process proceeds to ST11.
(1) The continuous printing number N1 is added to the cumulative printing number N2. That is, N2 = N2 + N1.
(2) The continuous print number N1 is stored together with the current time and the print mode.
Next, the processes of ST11 to ST14 are executed.

(Description of flowchart of discharge setting process)
FIG. 9 is an explanatory diagram of a flowchart of developer discharge setting processing according to the second embodiment.
In ST41, the current average image density AC1 is calculated from the number of pixels M1. Then, the process proceeds to ST42.
In ST42, the integrated number N4 of the number of printed sheets for the past 24 hours from the current time is calculated. Then, the process proceeds to ST43.
In ST43, it is determined whether or not the cumulative number N4 is greater than or equal to the high frequency determination number Nd. If yes (Y), the process proceeds to ST44, and, if no (N), the process proceeds to ST47.
In ST44, it is determined whether or not the current average image density AC1 is equal to or higher than the high-frequency low-density determination value ACa. If yes (Y), the process proceeds to ST45, and, if no (N), the process proceeds to ST46.
In ST45, the width L of the toner band 1 is set to L = 0. Then, the discharge setting process in FIG. 9 ends.
In ST46, the width L of the toner band 1 is set to L = L3. Then, the discharge setting process in FIG. 9 ends.

In ST47, it is determined whether or not the cumulative number N4 is greater than or equal to the low frequency determination number Ne. If yes (Y), the process proceeds to ST48, and, if no (N), the process proceeds to ST51.
In ST48, it is determined whether or not the current average image density AC1 is equal to or higher than the medium-frequency low-density determination value ACa. If yes (Y), the process proceeds to ST49, and, if no (N), the process proceeds to ST50.
In ST49, the width L of the toner band 1 is set to L = 0. Then, the discharge setting process in FIG. 9 ends.
In ST50, the width L of the toner band 1 is set to L = L2. Then, the discharge setting process in FIG. 9 ends.

In ST51, it is determined whether or not the current average image density AC1 is equal to or higher than a low-frequency low-density determination value ACa ′. If yes (Y), the process proceeds to ST52, and, if no (N), the process proceeds to ST53.
In ST52, the width L of the toner band 1 is set to L = 0. Then, the discharge setting process in FIG. 9 ends.
In ST53, the width L of the toner band 1 is set to L = L1. Then, the discharge setting process in FIG. 9 ends.

(Operation of Example 2)
The image forming apparatus U according to the second embodiment of the present invention having the above-described configuration is configured to determine the usage status of the image recording apparatus U3 over a long period of time by using the average image density AC0 from the last time to the previous time of the first embodiment. In other words, the usage status over a relatively long period as an example of the second period is determined from the cumulative number of sheets in the past 24 hours. Then, based on the degree of long-term developer deterioration based on the cumulative number N4 and the most recent average image density AC1, it is determined that there is little deterioration when the developer is replaced, and the toner band 1 Is not formed and the toner band 1 having a length corresponding to the progress of deterioration is formed based on the long-term use state.
Accordingly, in the image forming apparatus U of the second embodiment, as in the first embodiment, the wasteful developer discharge is reduced and the frequency of replacement of the collection container is suppressed from being excessive compared to the conventional configuration. .

Next, the image forming apparatus U according to the third embodiment of the present invention will be described. In the description of the third embodiment, the same reference numerals are given to the components corresponding to the components of the first embodiment, and Detailed description is omitted. The third embodiment is different from the first embodiment in the following points, but is configured in the same manner as the first embodiment in other points.

(Description of the control part C of Example 3)
FIG. 10 is a diagram corresponding to FIG. 3 of the first embodiment, and is a block diagram of a control unit of the printer of the third embodiment of the present invention.
10, the control unit C of the image forming apparatus U according to the third embodiment includes a band density setting unit C21 instead of the bandwidth setting unit C9B9 in the control unit C of the image forming apparatus U according to the first embodiment.

C21: Band density setting means A band density setting means C21 as an example of a developer discharge amount setting means sets the density BC of the toner band 1, which is a discharged image, according to the degree of deterioration of the developer. Set the developer discharge amount. The band density setting means C21 of the third embodiment consumes a large amount of developer when the current average image density AC1 is a high image density from the previous discharging operation in the first period, that is, when AC1 ≧ ACa. Judging that the deterioration is small, the density BC of the toner band 1 is set to BC = 0, that is, the toner band 1 is not formed. Further, when the previous average image density AC0 is high from the previous time when the current average image density AC1 is low density and the second period, that is, when AC1 <ACa and AC0 ≧ ACb, the previous time from the previous time. In the meantime, it is determined that the developer is sufficiently consumed, the overall consumption tendency is large, and the deterioration is small as a whole, and the density BC of the toner band 1 is set to 0.

Further, when the current average image density AC1 is low density and the previous average image density AC0 is medium density, that is, when AC1 <ACa and ACc ≦ AC0 <ACb, the overall consumption tendency is moderate. Therefore, it is determined that the deterioration is moderate, and the density BC of the toner band 1 is set to the first band density BC1. In Example 3, the first band density BC1 is set to BC1 = 30 [%] as an example.
Further, when the current average image density AC1 is low and the previous average image density AC0 is also low, that is, when AC1 <ACa and AC0 <ACc, the overall consumption tendency is small and the deterioration progresses. Therefore, the density BC of the toner band 1 is set to the second band density BC2. In Example 3, the second band density BC2 is set to BC2 = 100 [%], which is a value larger than the first band density BC1, as an example.
In Embodiment 3, the length of the toner band 1 in the main scanning direction and the sub-scanning direction is fixed to a preset length.

(Explanation of flowchart of Example 3)
Next, a control flow in the image forming apparatus U according to the third embodiment will be described with reference to a flow chart, a so-called flowchart.
(Description of flowchart of discharge setting process)
FIG. 11 is an explanatory diagram of a flowchart of developer discharge setting processing according to the third embodiment, and corresponds to FIG. 6 according to the first embodiment.
In FIG. 11, in the developer discharge setting process of the third embodiment, ST24 ′, ST27 ′, and ST28 ′ are executed in place of ST24, ST27, and ST28 with respect to the developer discharge setting process of the third embodiment. Since the other processes are the same except for the differences, the same processes are denoted by the same ST numbers, and detailed description thereof is omitted.
In ST24 ′ of FIG. 11, the density BC of the toner band 1 is set to BC = 0. Then, the discharge setting process in FIG. 11 ends.
In ST27 ′, the density BC of the toner band 1 is set to BC = BC1. Then, the discharge setting process in FIG. 11 ends.
In ST28 ′, the density BC of the toner band 1 is set to BC = BC2. Then, the discharge setting process in FIG. 11 ends.

(Operation of Example 3)
In the image forming apparatus U according to the third embodiment of the present invention having the above-described configuration, the developer discharge amount is changed by changing the width L in the sub-scanning direction of the toner band 1 according to the first embodiment. The developer discharge amount is changed by changing the density BC of the toner band 1. Accordingly, in the image forming apparatus U of the third embodiment, similarly to the first embodiment, the developer discharge amount is controlled not only according to the most recent use situation but also according to the long-term use situation, and thus has the conventional configuration. In comparison, wasteful developer discharge is reduced, and the frequency of replacement of the collection container is suppressed from becoming excessive.

Next, the image forming apparatus U according to the fourth embodiment of the present invention will be described. In the description of the fourth embodiment, components corresponding to the components of the first and second embodiments are denoted by the same reference numerals. Detailed description thereof will be omitted. The fourth embodiment is different from the first and second embodiments in the following points, but is configured in the same manner as the first and second embodiments in other points.

(Description of the control part C of Example 4)
FIG. 12 is a diagram corresponding to FIG. 7 of the second embodiment, and is a block diagram of the control unit of the printer of the fourth embodiment of the present invention.
In FIG. 12, the control unit C of the image forming apparatus U according to the fourth embodiment replaces the first period determination unit C9A and the discharge setting unit C9B ′ in the control unit C of the image forming apparatus U according to the second example. Period discriminating means C9A ″ and discharge setting means C9B ″.

C9A ″: first period determining means The first period determining means C9A ″ includes a band creation interval storage means C31 and a discharge timing determining means C9A2 ″, and whether or not the first period has elapsed. The first period discriminating means C9A ″ of Embodiment 4 uses the image forming apparatus as an example of the first period based on the continuous print number N1 or the cumulative print number N2 as an example of the number of image formations. It is determined whether or not the toner band creation interval Nf related to U has passed.
C31: Band Creation Interval Storage Unit The band creation interval storage unit C31 is a determination value for determining whether it is time to create a toner band, that is, whether the first period has elapsed. The band creation interval Nf is stored.

C9A2 ″: Discharge Timing Determination Unit The discharge timing determination unit C9A2 ″ determines whether or not it is time to perform the discharge operation for creating the toner band 1 and discharging the developer from the developing devices Gy to Gk. The discharge timing discriminating means C9A2 ″ of the fourth embodiment has reached the timing for executing the discharge operation when the continuous print number N1 or the cumulative print number N2 is equal to or greater than the band creation interval Nf. It is determined that the period has elapsed.
C9B ″: discharge setting means The discharge setting means C9B ″ includes an average image density calculation means C9B2, an integrated number calculation means C14, a high frequency determination number storage means C15, and a low frequency determination number storage means C16, A second period deterioration determining means C32; a current low density determination value storage means C9B4; a first period deterioration determining means C33; and a band creation interval setting means C34. The amount of developer discharged from Gk is set for each color of Y, M, C, and K.

C32: Second Period Degradation Determination Unit The second period deterioration determination unit C32 determines the usage frequency of the developing devices Gy to Gk in the second period based on the integrated number N4 and the frequency determination number Nd, Ne. By determining, the consumption tendency of the developer in the developing devices Gy to Gk, that is, the deterioration tendency is determined. In the fourth embodiment, when N4 ≧ Nd, it is determined that the image forming operation is frequent and the deterioration tendency is high, and when Ne ≦ N4 <Nd, it is determined that the deterioration tendency is medium and the deterioration tendency is medium. In the case of <Ne, it is determined that the deterioration tendency is low and the deterioration frequency is low.

C33: First Period Deterioration Determination Unit The first period deterioration determination unit C33 is configured so that the developer in the developing devices Gy to Gk is supplied during the period from the previous discharge operation to the current discharge operation as an example of the first period. It is determined whether or not it has deteriorated. Deterioration determining means C33 of the first period of Example 4, in the first period, if the consumption amount of the developer in the current image device Gy~Gk small, stirring members G2 remains most of the developer is not used, When it is determined that there is a high possibility that the developer is agitated and deteriorated in G3, and the amount of developer consumed is large, new developer is replenished from the toner cartridges Ky to Kk, and the developer deteriorated as a whole Determine that it is unlikely to be included.

C34: Band Creation Interval Setting Unit A band creation interval setting unit C34, which is an example of a developer discharge amount setting unit, sets the developer discharge amount according to the degree of developer deterioration. The band creation interval setting unit C34 according to the fourth exemplary embodiment sets the developer discharge amount by setting the creation interval Nf of the toner band 1 that is a discharged image, that is, the frequency of creating the toner band 1.
The band creation interval setting means C34 of the fourth embodiment determines that the developer is frequently replaced when the current average image density AC1 is high, that is, when AC1 ≧ ACa. It is determined that the deterioration of the developer is small, and the creation interval Nf of the toner band 1 is set to the first creation interval N1. In the fourth embodiment, the first creation interval N1 is set to N1 = 100 [sheets].
In addition, when the average image density AC1 is low and the cumulative number N4 is less than the low frequency determination number Ne, that is, when AC1 <ACa and N4 <Ne, the replacement of the developer is small, but image formation is also possible. It is performed at a low frequency, and it is determined that the developer is hardly deteriorated as a whole, and the creation interval Nf of the toner band 1 is set to the first creation interval N1.

Further, when the current average image density AC1 is a low image density and the integrated number N4 is equal to or higher than the low frequency determination number Ne and less than the high frequency determination number Nd, that is, when AC1 <ACa and Ne ≦ N4 <Nd, development is performed. Since the replacement of the agent is small and image formation is performed at a medium frequency, it is determined that the deterioration of the developer tends to progress as a whole, and the creation interval Nf of the toner band 1 is set to the second creation interval N2. In the fourth embodiment, the second creation interval N2 is set to N2 = 60 [sheets], which is a smaller value than the first creation interval N1.
In addition, when the average image density AC1 this time is a low image density and the cumulative number N4 is greater than or equal to the high frequency determination number Nd, that is, when AC1 <ACa and N4 ≧ Nd, the change of the developer is small, and the image The formation is also performed at a high frequency, and it is determined that the developer is most easily deteriorated as a whole, and the creation interval Nf of the toner band 1 is set to the third creation interval N3. In the fourth embodiment, the third creation interval N3 is set to N3 = 30 [sheets], which is a smaller value than the second creation interval N2.

(Explanation of flowchart of Example 4)
Next, a control flow in the image forming apparatus U according to the fourth embodiment will be described with reference to a flowchart, that is, a so-called flowchart.
(Description of flowchart of developer discharge control process)
FIG. 13 is an explanatory diagram of a flowchart of the developer discharge control process of the fourth embodiment, and corresponds to FIG. 8 of the second embodiment.
In FIG. 13, in the developer discharge control process of the fourth embodiment, ST5 ″ and ST11 ″ are executed in place of ST5 and ST11 with respect to the developer discharge control process of the second embodiment, and ST6 and ST12. Since only the contents of the discharge setting process subroutine are different and the other processes are the same, the same processes are denoted by the same ST numbers, and detailed description thereof is omitted.

In ST5 ″ in FIG. 13, it is determined whether or not the continuous print number N1 is equal to or greater than the band creation interval Nf. If yes (Y), the process proceeds to ST6, and if no (N), the process proceeds to ST9.
In ST11 ″, it is determined whether or not the cumulative number of printed sheets N2 is equal to or greater than the band creation interval Nf. If yes (Y), the process proceeds to ST12, and if no (N), the process returns to ST1.

(Description of flowchart of discharge setting process)
FIG. 14 is an explanatory diagram of a flowchart of developer discharge setting processing according to the fourth embodiment, and corresponds to FIG. 9 according to the second embodiment.
In ST41 of FIG. 14, the current average image density AC1 is calculated from the number of pixels M1. Then, the process proceeds to ST42.
In ST42, the integrated number N4 of the number of printed sheets for the past 24 hours from the current time is calculated. Then, the process proceeds to ST61.
In ST 61, it is determined whether or not the average image density AC1 is equal to or higher than the low density determination value ACa. If yes (Y), the process proceeds to ST62, and, if no (N), the process proceeds to ST63.
In ST62, the band creation interval Nf is set to the first creation interval N1. Then, the discharge setting process in FIG. 14 ends.

In ST63, it is determined whether or not the cumulative number N4 is greater than or equal to the high frequency determination number Nd. If yes (Y), the process proceeds to ST64, and, if no (N), the process proceeds to ST65.
In ST64, the band creation interval Nf is set to the third creation interval N3. Then, the discharge setting process in FIG. 14 ends.
In ST65, it is determined whether or not the cumulative number N4 is equal to or greater than the low frequency determination number Ne. If yes (Y), the process proceeds to ST66, and, if no (N), the process returns to ST62.
In ST66, the band creation interval Nf is set to the second creation interval N2. Then, the discharge setting process in FIG. 14 ends.

(Operation of Example 4)
In the image forming apparatus U according to the fourth embodiment of the present invention having the above-described configuration, as in the second embodiment, the usage status over a relatively long period as an example of the second period is determined from the accumulated number of sheets in the past 24 hours. doing. Based on the long-term developer consumption tendency based on the cumulative number N4 and the latest average image density AC1, if the developer is frequently replaced, it is determined that the deterioration is small, and the toner band 1 is set. The interval for forming becomes longer, and the discharged amount of developer is reduced as a whole. When the replacement of the developer is small, the length of the formation interval Nf of the toner band 1 is shortened and the developer is frequently discharged as a whole as the deterioration easily proceeds based on the long-term use situation. Will come to be.
Therefore, in the image forming apparatus U of the fourth embodiment, as in the first to third embodiments, wasteful developer discharge is reduced and the frequency of replacement of the collection container is suppressed from being excessive compared to the conventional configuration. Is done.
In the fourth embodiment, the same creation interval Nf is used for determining the continuous print number N1 and the cumulative print number N2. However, the creation interval Nf1 for the continuous print number N1 and the creation interval Nf2 for the cumulative print number N2 are used. It is also possible to set each separately. For example, it is possible to set Nf1 = Nf and Nf2 = 2 × Nf.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various change is performed within the range of the summary of this invention described in the claim. It is possible. Modification examples (H01) to (H06) of the present invention are exemplified below.
(H01) In the above-described embodiment, the present invention is not limited to a copying machine as an example of an image forming apparatus, and can be applied to an image forming apparatus such as a printer or a FAX. Further, the present invention is not limited to a color image forming apparatus, and can be applied to a monochrome image forming apparatus. Further, the present invention is not limited to a tandem type image forming apparatus, and can be applied to a rotary type image forming apparatus.

(H02) In the above-described embodiment, the configurations of Embodiments 1 to 4 can be combined with each other. For example, the second embodiment and the third embodiment are combined to adjust the density BC of the toner band 1 in the second embodiment, or the first to fourth embodiments are combined to create the width L and the density BC of the toner band 1. It is also possible to adjust all the intervals Nf.
(H03) In the above-described embodiment, the exemplified specific numerical values and the like can be arbitrarily changed according to the design, specifications, and the like.
(H04) In the above-described embodiment, the configuration in which the determination is performed based on the number of printed sheets N1 and the number of pixels M1 is illustrated. However, the present invention is not limited to this. Arbitrary parameters linked to the usage status of the recording device U3 and the usage status of the long-term image recording device U3 can be adopted. For example, rotation time and accumulated rotation speed of the photosensitive member Py~Pk and developing roller R0, accumulated rotation distance, the toner dispensing server device U3a replenishment times and cumulative replenishment time and the like, it is possible to employ any parameter.

(H05) In the above-described embodiment, the process control is preferably executed after the developer discharging operation, but can be executed before, and can be executed independently without being linked with the discharging operation. Is possible.
(H06) In the above-described embodiment, the determination as to whether or not to start the creation of the toner band is not limited to the configuration illustrated in the embodiment. For example, a configuration in which determination is performed using only the cumulative number of printed sheets as a parameter is possible. . In addition, for example, when a job is counted up one by one, if the cumulative value from the previous toner band creation exceeds 50, toner band creation is executed during the job, and the cumulative value at the end of the job It is also possible to create a toner band at the end of the job when the number of toner exceeds 20 sheets.

1 ... discharged image,
AC0, AC1 ... Image density,
C9: Developer discharge control means,
Gy, Gm, Gc, Gk ... developing device,
N1, N2 ... number of image formations,
Py, Pm, Pc, Pk ... image carrier,
ROSy, ROSm, ROSc, ROSk ... latent image forming device,
U: Image forming apparatus,
U3a ... replenishment device.

Claims (6)

An image carrier,
A latent image forming apparatus for forming a latent image on the surface of the image carrier;
A developing device for developing the latent image on the surface of the image carrier into a visible image;
A replenishing device for replenishing developer to the developing device;
Discharge setting means for setting the amount of developer discharged from the developing device;
A discharged image for forming a latent image on the surface of the image holding member, developing with the developing device, and discharging the developer in the developing device , according to the amount of developer discharged set by the discharge setting means. A discharge control means for the developer to be formed ;
With
The discharge setting unit is configured to determine the discharge amount of the developer based on the image density during the image forming operation from the previous discharge amount setting to the current discharge amount setting and the number of image formations in a preset period. Set
When the image density is lower than a predetermined image density and the number of image formations is lower than a predetermined image formation number, the image density is lower than the predetermined image density and the number of image formations is The discharge amount is set to be smaller than when the number of times of image formation is higher than the predetermined number.
An image forming apparatus comprising and this.   The image forming apparatus according to claim 1, wherein the preset period is 24 hours.   The image forming apparatus according to claim 1, wherein the preset period is a time zone divided in advance in one day. An image carrier,
A latent image forming apparatus for forming a latent image on the surface of the image carrier;
A developing device for developing the latent image on the surface of the image carrier into a visible image;
A replenishing device for replenishing developer to the developing device;
Discharge setting means for setting the amount of developer discharged from the developing device;
A discharged image for forming a latent image on the surface of the image holding member, developing with the developing device, and discharging the developer in the developing device , according to the amount of developer discharged set by the discharge setting means. A discharge control means for the developer to be formed ;
With
The discharge setting means includes a first image density during an image forming operation from a previous discharge amount setting to a current discharge amount setting, and a second image density calculated before the previous discharge amount setting. And set the developer discharge amount based on
When the first image density is lower than a predetermined first determination value and the second image density is higher than a predetermined second determination value, the first image density is the first determination value. It is set so that less developer is discharged than when the second image density is lower than the determination value of 1 and the second image density is lower than the second determination value.
An image forming apparatus comprising and this.   The discharge setting unit performs discharge setting when the number of continuous prints reaches a predetermined number or when the cumulative number of prints reaches a predetermined number.
  The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The development for setting the discharge image creation condition configured by at least one of the width, density, and frequency of the discharged image in the sub-scanning direction according to the developer discharge amount set by the discharge setting unit. Agent discharge control means,
Claims 1, characterized in that with a to the image forming apparatus according to any one of 5.

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