JP2010145429A - Image forming device, and method of discharging deteriorated developer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To discharge a developer deteriorated by an applied load. <P>SOLUTION: This image forming device (U) includes an accumulated consumption amount measuring means (C5) for measuring an accumulated consumption amount (P1) that is an accumulation amount of a consumption amount of the developer, a developing device accumulated driving time measuring means (C6) for measuring an accumulated driving time (t1) of a developing device (G), a developer deterioration determining means (C7) for determining whether the developer is deteriorated or not by stirring the developer under the condition where the developer is consumed at a low level for a long period in the developing device, based on the accumulated consumption amount (P1) and the accumulated driving time (t1) of a developing device (G), and a developer discharge means (C8) for discharging the deteriorated developer from a visible image forming device (U2), when the developer is determined to be deteriorated by the developer deterioration determining means (C7). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and a deteriorated developer discharging method.

In a conventional electrophotographic image forming apparatus, a technique described in Patent Document 1 below is known as a technique for changing an image forming condition such as an applied voltage or an exposure amount in accordance with deterioration or wear of a member over time. It has been.
In Japanese Patent Laid-Open No. 5-257354 as Patent Document 1, the amount of decrease in the film thickness of the photoconductor is measured based on the number of images formed, and the development bias voltage or the exposure amount is set according to the amount of decrease in the film thickness. Techniques for increasing are described.

JP-A-5-257354 ("0010")

  An object of the present invention is to discharge a developer that has deteriorated due to a load.

In order to solve the technical problem, an image forming apparatus according to claim 1 is provided.
A rotating image carrier, a latent image forming device that forms a latent image on the surface of the image carrier, a developing unit that develops the latent image formed on the surface of the image carrier into a visible image, and the image carrier A visible image forming apparatus comprising: a transfer device that applies a transfer voltage for transferring a visible image on the surface to the medium and transfers the visible image on the surface of the image carrier to the medium;
A cumulative consumption measuring means for measuring cumulative consumption which is a cumulative value of developer consumption;
A developer cumulative drive time measuring means for measuring the cumulative drive time of the developer;
Developer deterioration determination means for determining whether or not the developer has been deteriorated by being stirred in the developer for a long time in a state where the consumption of the developer is small, based on the cumulative consumption and the cumulative driving time of the developer. When,
A deteriorated developer discharging means for discharging the deteriorated developer from the visible image forming apparatus when the developer deterioration determining means determines that the developer has deteriorated;
It is provided with.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect,
When the developer deterioration determining means determines that the developer has deteriorated, transfer with a polarity opposite to the transfer voltage for transferring the visible image on the surface of the image carrier to the medium without conveying the medium After applying the voltage to accumulate the deteriorated developer on the surface of the transfer device, the transfer device applies the transfer voltage for transferring the visible image on the surface of the image carrier to the medium while transporting the medium. The deteriorated developer discharging means for discharging the deteriorated developer out of the apparatus by executing a deteriorated developer discharging operation for transferring the deteriorated developer accumulated on the surface to the medium;
It is provided with.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect,
A cleaner for collecting and cleaning the residual developer attached to the surface of the image carrier after the visible image is transferred to the medium;
A residual developer transport member that transports the residual developer collected by the cleaner to the developer;
It is provided with.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects,
Cumulative driving time determination means for determining whether or not the cumulative driving time of the developing unit has reached or exceeded a preset cumulative driving time determination value;
When the cumulative drive time becomes equal to or greater than the cumulative drive time determination value, the developer is used for a long time in a state where the developer consumption is low, based on the cumulative consumption and the cumulative drive time of the developer. The developer deterioration determining means for determining whether or not the toner has been deteriorated by stirring,
It is provided with.

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects,
Based on the environment in which the image forming apparatus main body is installed, an environment determination unit that determines whether or not the developer is likely to deteriorate.
When it is determined by the environment determining means that the developer is likely to deteriorate, the developer is long in a state where the consumption of the developer is small based on the cumulative consumption and the cumulative driving time of the developing device. The developer deterioration determining means for determining whether or not the developer has been deteriorated by being stirred in the time developing device;
It is provided with.

In order to solve the technical problem, the deteriorated developer discharging method of the invention according to claim 6 comprises:
Cumulative consumption of developer consumed when developing the latent image on the surface of the rotating image carrier into a visible image, and a developer for developing the latent image formed on the surface of the image carrier into a visible image A developer deterioration determining step for determining whether or not the developer has been deteriorated by being stirred in the developing device for a long time in a state where the consumption of the developer is low, based on the cumulative driving time;
A deteriorated developer discharging step of discharging the deteriorated developer when the developer deterioration determining means determines that the developer has deteriorated;
It is characterized by performing.

According to the first and sixth aspects of the invention, it is possible to discharge the developer that has deteriorated due to the load.
According to the second aspect of the present invention, the deteriorated developer can be discharged out of the apparatus.
According to the third aspect of the present invention, the developer recovered by the cleaner can be reused, and the developer recovered by the cleaner and subjected to a load can be discharged.
According to the fourth aspect of the present invention, compared with the configuration in which the deterioration of the developer is determined when there is a high possibility that the amount of the developer deteriorated by stirring for a short time is less than the cumulative drive time determination value, the determination is useless. As well as a decrease in productivity due to the discharging operation with a small amount of deteriorated developer.
According to the fifth aspect of the present invention, it is possible to reduce wasteful discrimination as compared with the configuration in which the degradation of the developer is discriminated in an environment in which the developer is not easily degraded, and the discharging operation with a small amount of the degraded developer. It is possible to suppress a decrease in productivity due to performing.

Next, examples which are specific examples of embodiments of the present invention 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.

FIG. 1 is a perspective view of the image forming apparatus according to the first exemplary embodiment.
In FIG. 1, a printer U as an example of an image forming apparatus according to the first exemplary embodiment is provided with a first paper discharge tray TRh as an example of a first medium discharge unit, a so-called face-down tray TRh, on an upper surface of a printer body U1. Yes. An operation unit UI for a user to perform an input operation is provided at the front upper surface of the first discharge tray TRh on the leading end side in the medium discharge direction, and a setting key or the like is provided on the operation unit UI. A front panel Ua as an example of a front opening / closing portion is disposed on the upper front surface of the printer U, and a lower end portion of the front panel Ua is rotatably supported by the printer U body by a rotation shaft extending in the left-right direction. Therefore, when replacing a toner cartridge as an example of a developer container, a process unit as an example of a visible image forming unit, etc., the front panel Ua can be opened and replaced.

FIG. 2 is a longitudinal sectional view of the image forming apparatus according to the first embodiment.
In FIG. 2, electrical signals such as image information and control signals transmitted from the host computer HC as an example of an image information transmitting apparatus electrically connected to the printer U are sent to a controller C as an example of a control unit of the printer U. Entered. The controller C temporarily stores input image information, converts the image information into information for forming a latent image at a preset time, and performs laser driving as an example of a latent image forming apparatus driving circuit. Output to the circuit DL.
The laser drive circuit DL outputs a drive signal to the latent image forming device ROS according to the input information. The operation of the operation unit UI, laser drive circuit DL, power supply circuit E for applying a voltage to a developing roll Ga and a transfer roll Rt, which will be described later, is controlled by a controller C.

FIG. 3 is an enlarged view of a main part of the toner image forming apparatus portion of FIG.
2 and 3, a toner image forming apparatus U2 as an example of a visible image forming apparatus that forms a black toner image is disposed on the left side of the latent image forming apparatus ROS. A laser beam L as an example of latent image forming light emitted from the latent image forming device ROS is incident on the rotating photoconductor PR.
2 and 3, the toner image forming apparatus U2 according to the first exemplary embodiment includes a photosensitive member PR as an example of an image carrier that rotates in the direction of an arrow about a rotation axis PRa, and a charging roll CR as an example of a charger. A developing device G and an image carrier cleaner CL as an example of an image carrier cleaner. Further, the toner image forming apparatus U2 is unitized and is configured to be detachable from the image forming apparatus main body U1 as a process unit. The process unit U2 is attached and detached with the front cover Ua supported on the front surface of the image forming apparatus main body U1 being openable and closable.

2 and 3, the surface of the photoreceptor PR is uniformly charged by the charging roll CR, and then exposed and scanned by the laser beam L of the latent image forming device ROS at the latent image writing position Q1. A latent image is formed. The surface of the photoconductor PR on which the electrostatic latent image is formed rotates and moves sequentially through the development area Q2 and the transfer area Q3.
The developing device G includes a developing container V that stores therein toner as an example of a developer. In the developing container V, a developing roll Ga as an example of a developer holder that is opposed to the photoconductor PR in the developing region Q2 and to which a developing voltage is applied is rotatably supported. In the developing container V, toner agitating members Gb and Gc for conveying the toner while being agitated to the developing roll Ga are rotatably supported. Accordingly, the toner held on the surface is transported to the developing area Q2 as the developing roll Ga rotates, and the electrostatic latent image on the photoconductor PR passing through the developing area Q2 becomes a toner image as an example of a visible image. Developed.

One end of a supply path of a cartridge toner supply device TH1 as an example of a developer supply device fixedly supported by the printer U is connected to the front end portion of the developing container V. The other end of the supply path of the cartridge toner supply device TH1 is connected to a discharge port TC3 of a toner cartridge TC as an example of a developer container.
In FIG. 2, the toner cartridge TC has a cartridge body TC1 as an example of a container body that accommodates toner therein, and a toner transport member TC2 as an example of an in-container transport member is rotatable in the cartridge body TC1. It is supported by. Therefore, according to the consumption of toner in the developing device G, the toner conveying member TC2 is driven to rotate, and the toner in the cartridge body TC1 is conveyed to the discharge port TC3. The toner discharged from the discharge port TC3 is transported to the developing container V of the developing device G by a replenishment transport member (not shown) in the replenishment path of the cartridge toner replenishing device TH1.

The toner cartridge TC is configured to be detachable by being inserted into and removed from the printer U in the front-rear direction. The toner cartridge TC is attached and detached with the front cover Ua supported to be openable and closable on the front surface of the image forming apparatus main body U1 opened.
The photoconductor PR, the charging roll CR, the electrostatic latent image forming device ROS, the developing device G, and the like constitute a toner image forming device U2 that forms a toner image on the photoconductor PR.

1 and 2, a plurality of paper feed trays TR <b> 1 to TR <b> 4 as an example of a medium storage unit are provided below the printer U. The plurality of paper feed trays TR1 to TR4 contain a recording sheet S as an example of a medium to be conveyed to the transfer area Q3.
In FIG. 2, rails RL <b> 1 and RL <b> 1 are arranged inside the lower portion of the printer U as an example of an entrance / exit guide member that movably supports both left and right ends of the input / output trays TR <b> 1 to TR <b> 4. Accordingly, the paper feed trays TR1 to TR4 are supported by the pair of left and right rails RL1 and RL1 so as to be movable in the front-rear direction, and the paper feed trays TR1 to TR4 can enter and exit from the front surface of the printer U.

In FIG. 2, a paper feeding device K is disposed on the paper feeding side of each of the paper feeding trays TR1 to TR4. The sheet feeding device K includes a pick-up roll Rp as an example of a medium take-out member, and a separating roll Rs as an example of a separating member made up of a feed roll as an example of a medium transport member and a retard roll as an example of a medium separating member. Have
The recording sheets S taken out by the pickup roll Rp of the paper feeding device K are separated one by one by the separation roll Rs and fed to the main body conveyance path SH1. The fed sheet S is transported by a sheet transport roll Ra as an example of a plurality of transport members arranged in the main body transport path SH1. The sheet S conveyed by the sheet conveying roll Ra is conveyed to the transfer area Q3 by a registration roll Rr as an example of a sheet feeding timing adjusting member in accordance with the timing when the toner image on the surface of the photoreceptor PR moves to the transfer area Q3. Is done.

  In addition, a manual feed tray TR0 as an example of a manual paper feed unit is mounted on the left side of the printer U. The sheet S fed from the manual feed tray TR0 passes through the manual feed transport path SH2 from the manual feed additional transport path SH5, and is transported by the sheet transport roll Ra on the main body transport path SH1, and is supplied to the registration roll Rr. Is transferred to the transfer area Q3.

In FIG. 2, a transfer roll Rt as an example of a transfer device to which a transfer voltage is applied is disposed in the transfer region Q3. The transfer roll Rt is in contact with the photoconductor PR at a preset pressure in the transfer region Q3, and transfers the toner image on the photoconductor PR to the sheet S passing through the transfer region Q3.
After the toner image on the surface of the photoconductor PR is transferred to the sheet S in the transfer region Q3, the photoconductor PR removes, collects, and cleans residual toner as an example of the residual developer attached to the surface by the cleaner CL. The The photoconductor PR from which the residual toner adhering to the surface is collected by the cleaner CL is charged again by the charging roll CR.

The sheet S on which the unfixed toner image is transferred in the transfer area Q3 is conveyed to the fixing area Q4 of the fixing device F with the toner image being unfixed, and is an example of a fixing member disposed in the fixing area Q4. The toner image is fixed by the pair of fixing rolls Fh and Fp.
The toner image forming device U2, the transfer roll Rt, and the fixing device F constitute an image recording member U2 + Rt + F that records an image on the sheet S.
The sheet S on which the fixing toner image is formed is guided by a sheet guide as an example of a medium guide member and conveyed to a discharge roll R1 as an example of a discharge member. The sheet S is discharged from the sheet discharge port Ha, which is an example of a medium discharge port, to the first paper discharge tray TRh by the paper discharge roll R1.

Above the fixing device F inside the printer U, a main body reversing path SH3 connected to the sheet discharge port Ha is provided. A sheet reversing device U3 as an example of a medium reversing device, which is an additional device, is mounted on the manual feed tray TR0. An optional sheet reversing path SH4 as an example of an additional reversing path connected to the main body side reversing path SH3 is formed inside the sheet reversing device U3. Therefore, during double-sided printing, the sheet S on which the toner image is fixed in the fixing area Q4 passes through the main body sheet reversing path SH3 and the option sheet reversing path SH4, is conveyed to the registration roll Rr, and is transferred to the transfer area Q3. Resent.
The main body side reversing path SH3 and the option sheet reversing path SH4 constitute a reversing path SH3 + SH4.

  Further, the sheet reversing device U3 is provided with an optional paper discharge tray TRh1, which is an example of an additional medium discharge portion that is discharged in a state where the image recording surface of the sheet S is the upper surface, so-called face-up tray TRh1. . An optional sheet discharge path SH6 as an example of an additional discharge path is provided between the optional discharge tray TRh1 and the main body side reversing path SH3, and it is designated by the user to be discharged to the optional discharge tray TRh1. In this case, the sheet S passes through the option sheet discharge path SH6 from the main body side reversing path SH3 and is discharged to the option discharge tray TRh1.

(Developer)
4 is a cross-sectional view taken along line IV-IV in FIG.
3 and 4, the developing container V of the developing device G includes a developing container main body 1 and a developing container cover 2 as an example of a developing device lid member that covers the upper end of the developing container main body 1. In FIG. 4, a front projecting portion 3 that projects forward is integrally formed at the front end of the developing container body 1. In FIG. 3, a layer thickness regulating member SK extending in the front-rear direction is fixedly supported at the left end of the developer container cover 2. The front end of the layer thickness regulating member SK is disposed to face the developing roll Ga, and regulates the thickness of the toner layer attached to the developing roll Ga.

In FIG. 3, on the inner side of the developing container main body 1, a developing roll chamber 4 as an example of a developer holding body containing portion for containing the developing roll Ga, and a first stirring chamber 6 adjacent to the developing roll chamber 4 are provided. And a second stirring chamber 7 adjacent to the first stirring chamber 6.
In FIG. 4, the first stirring chamber 6 includes a first main stirring chamber 6 a on the developing container main body 1 side and a collected toner as an example of a collected developer inflow portion formed on the left portion 3 a side of the front protrusion 3. And a supply chamber 6b. The second stirring chamber 7 includes cartridge toner supply as an example of a second main stirring chamber 7a on the developing container main body 1 side and a new developer inflow portion formed on the right portion 3b side of the front projecting portion 3. Chamber 7b.

  In FIG. 4, the developer container cover 2 above the collected toner supply chamber 6b is formed with a collected toner supply port 2a as an example of a collected developer inflow port, and the developer container above the cartridge toner supply chamber 7b. The cover 2 is formed with a cartridge toner supply port 2b. The cartridge toner replenishing port 2b is connected to the cartridge toner replenishing device TH1 and replenishes toner from the toner cartridge TC. Further, the recovered toner replenishing port 2a is provided at the downstream end of the first stirring chamber 6, and the cartridge toner replenishing port 2b is provided at the upstream end of the second stirring chamber 7, so that each of the replenishing ports 2a and 2b is provided. The toner replenished from the toner, that is, the new toner or the collected toner is transported to the developing roll Ga immediately after the replenishment and is not used for development.

Between the first stirring chamber 6 and the second stirring chamber 7, portions other than both ends of the first main stirring chamber 6 a and the second main stirring chamber 7 a are partitioned by a partition wall 9. That is, the first main stirring chamber 6a and the second main stirring chamber 7a are configured such that the developer can flow into each other at the front inflow portion E1 and the rear inflow portion E2 at both ends in the front-rear direction.
The first stirring chamber 6 and the second stirring chamber 7 constitute the circulation stirring chamber 6 + 7 of the first embodiment.

  3 and 4, the developing roll Ga is a conventionally known developing roll having a magnet roll 11 fixedly supported on the developing container V and a developing sleeve 12 rotatably supported on the outer periphery of the magnet roll 11. . The toner in the developing roll chamber 4 and the first main stirring chamber 6 a is attracted and held on the surface of the developing sleeve 12 of the developing roll Ga by the magnetic force of the magnet roll 11. Further, both front and rear ends of the developing sleeve 12 are rotatably supported by a front wall and a rear wall of the developing roll chamber 4, and a gear as an example of a gear for a developer holder is provided at the rear end of the developing sleeve 12. G0 is fixedly supported. Therefore, when the drive is transmitted to the gear G0 and the developing sleeve 12 rotates, the developer held on the surface of the developing sleeve 12 is conveyed to the developing region Q2.

  3 and 4, the first stirring chamber 6 and the second stirring chamber 7 are provided with a first stirring member Gb and a second stirring member Gc that convey the toner while stirring. In FIG. 4, the first stirring member Gb includes a first rotating shaft 21 extending in the axial direction of the developing roll Ga, a spiral first main conveying blade 22 supported on the outer periphery of the rotating shaft 21, and a reverse conveying. And blades 23. The first main conveying blade 22 is provided from the rear inflow portion E2 to the front inflow portion E1 in order to convey the toner from the rear side to the front side. The reverse conveying blade 23 is provided corresponding to the collected toner replenishing port 2a, and the toner is formed in a spiral shape opposite to the first main conveying blade 22, and the conveying direction of the first main conveying blade 22 is The toner is caused to flow from the first stirring chamber 6 to the second stirring chamber 7 by conveying the toner in the opposite direction. The rotary shaft 21 is rotatably supported by the front wall of the left portion 3a of the front connection portion 3 and the rear wall of the developing container main body 1, and the rear end portion of the rotary shaft 21 is for the first stirring member. A gear G1 as an example of a gear is fixedly supported.

In FIG. 4, the second agitating member Gc includes a second rotating shaft 26, a multiple agitating and conveying blade 27 as an example of a helical replenishing conveying blade supported by the front end of the second rotating shaft 26, and A spiral second main transport blade 28 supported behind the multi-stirring transport blade 27 and a spiral reverse transport blade 29 supported at the rear end of the second rotating shaft 26 are provided.
The multiple agitating and conveying blades 27 are provided from the cartridge toner supply port 2b to the front side communication portion E1 in order to convey the toner from the front side to the rear side. The multi-stirring conveying blade 27 has a configuration in which the same spiral as the second main conveying blade 28 is doubled. Therefore, the toner conveyance speed by the multiple agitation conveyance blades 27 is faster than the conveyance speed by the second main conveyance blades 28.

The second main conveying blade 28 is provided from the front inflow portion E1 to the rear inflow portion E2 in order to convey the toner from the front side to the rear side. A plurality of flat blades 31 that are fixedly supported by the second rotating shaft 26 and extend along the axial direction are provided at the front end portion of the stirring and conveying blade 28. A flat blade 31 is also provided at the rear end of the second main transport blade 28. The flat blade 31 performs agitation without applying a conveying force to the toner.
The reverse conveying blade 29 is provided corresponding to the rear inflow portion E2, and conveys the toner from the second agitating chamber 7 by conveying the toner in the direction opposite to the conveying direction of the second main conveying blade 28. 1 It is made to flow into the stirring chamber 6. The second rotation shaft 26 is rotatably supported by the front wall of the right part 3b of the front connection part 3 and the rear wall of the developing container main body 1, and the rear end part is a gear as an example of a gear for the second stirring member. G2 is fixedly supported.

In FIG. 4, the gear G <b> 0 at the rear end of the developing sleeve 12 is engaged with the gear G <b> 1 of the first rotating shaft 21, and the gear G <b> 1 is engaged with the gear G <b> 2 of the second rotating shaft 26. A rotational force of a main motor as an example of a main drive source is transmitted to the gear G0. When the gear G0 is rotated by the main motor, the gear G1 rotates in a direction opposite to that of the gear G0. The gear G2 rotates in opposite directions. That is, the first stirring member Gb and the second stirring member Gc that rotate together with the gear G1 and the gear G2 rotate in opposite directions. Accordingly, the toner in the first stirring chamber 6 and the second stirring chamber 7 is conveyed and circulated in opposite directions by the rotation of the first stirring member Gb and the second stirring member Gc.
The first stirring member Gb and the second stirring member Gc constitute a toner stirring and conveying member Gb + Gc.
A developing device G is constituted by the developing container V, the developing roll Ga, the first stirring member Gb, the second stirring member Gc, and the like.

(Cleaner)
In FIG. 3, the cleaner CL has a cleaner container 41 as an example of a cleaning container disposed along the axial direction of the photoconductor PR. A cleaning blade 42 as an example of a cleaning member that contacts the surface of the photoconductor PR with a preset pressure and collects toner adhering to the surface of the photoconductor PR is supported on the lower right side of the cleaner container 41. . Above the cleaning blade 42, a collected toner conveying member 43 as an example of a residual developer conveying member is disposed.

In FIG. 3, similarly to the toner stirring and conveying members Gb and Gc, the collected toner conveying member 43 is constituted by a conveying member in which a helical conveying blade is supported on the outer periphery of the rotating shaft, a so-called auger. The toner collected in the cleaner container 41 is conveyed from the rear to the front. The drive of the collected toner conveying member 43 is configured to be transmitted from the gear G0 through a plurality of gears.
3 and 4, the toner transported to the front of the cleaner CL is a recovered toner transport path 44 as an example of a residual developer transport path that connects the front end of the cleaner CL and the recovered toner supply port 2a of the developer container V. Is dropped and conveyed, and flows into the developing container V and is replenished.
A toner image forming apparatus U2 that transports the toner collected by the cleaner CL to the developing device G and reuses it as described above is described in, for example, Japanese Patent Application Laid-Open No. 2008-37543 and the like. Various configurations can be employed.

(Description of the control part of Example 1)
FIG. 5 is a block diagram of the control unit of the image forming apparatus according to the first exemplary embodiment of the present invention.
In FIG. 5, the controller C is an input / output interface that performs input / output of signals to / from the outside and adjustment of input / output signal levels, etc .: I / O, a program in which necessary processing is performed, information and the like stored therein Only memory: ROM, Random access memory for temporarily storing necessary data: RAM, Central processing unit that performs processing according to the program stored in the ROM: Small information processing having CPU, oscillator, etc. The apparatus is constituted by a so-called microcomputer, and various functions can be realized by executing a program stored in the ROM.

(Signal output element connected to the controller C)
The controller C receives an output signal from a signal output element such as the operation unit UI, the temperature sensor SN1, and the humidity sensor SN2.
The operation unit UI includes a power button UI1, a display unit UI2, an input button UI3 such as an arrow button, a dirt reduction mode setting button UI4 as an example of a deteriorated developer discharge operation setting button, and the like.
The temperature sensor SN1 measures the environmental temperature that is the temperature in the printer U.
The humidity sensor SN2 measures the environmental humidity which is the humidity in the printer U.

(Controlled element connected to the controller C)
The controller C is connected to a main motor drive circuit D1, a power supply circuit E, a laser drive circuit DL, and other control elements as an example of a main drive source drive circuit, and outputs their operation control signals. .
The main motor drive circuit D1 rotationally drives the photosensitive member PR, the developing roller Ga of the developing unit G, the conveying members Gb and Gc, the collected toner conveying member 43 of the cleaner CL, the fixing device F, and the like via the main motor 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 Vg to the developing roller Ga of the developing device G.
The charging power source Eb applies a charging voltage Vc for charging the surface of the photoreceptor PR to the charging roll CR.
The transfer power supply circuit Ec applies a transfer voltage Vt to the transfer roll Rt.
The fixing power supply circuit Ed supplies heating power to the heater of the fixing device F.

(Function of the controller C)
The controller 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 controller C has the following functions.
C1: Job Control Unit The job control unit C1, which is an example of the image forming operation control unit, controls the driving of each member of the printer U, the application timing of each voltage, and the like when image information to be printed is received. Controls jobs that are forming operations.
C2: Main motor control means The main motor control means C2 as an example of the main drive source control means controls the drive of the main motor M1 via the main motor drive circuit D1, and controls the drive of the photoconductor PR 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 the voltage and power supply to each member.
C3A: Developing power supply circuit control means The developing power supply circuit control means C3A controls the developing power supply circuit Ea to control the application of the developing voltage Vg to the developing roll Ga of the developing device G.
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 application of the charging voltage Vc to the charging roll CR.

C3C: Transfer power supply circuit control means The transfer power supply circuit control means C3C has an image transfer voltage application means C3C1 and an inter-image region voltage application means C3C2, and controls the transfer power supply circuit Ec to transfer the image. The transfer voltage Vt applied to the roll Rt is controlled. In the transfer power supply circuit control unit C3C according to the first exemplary embodiment, the image transfer voltage applying unit C3C1 transfers the toner image on the surface of the photoconductor PR to the medium S when executing a job as an image forming operation. An image transfer voltage Vt1 having a polarity opposite to the charging polarity of the toner is applied to the roll Rt. In the inter-image area between the toner image and the next toner image, so-called inter-image area, the toner on the surface of the photoreceptor PR is prevented from adhering to the transfer roll Rt, and the toner adhering to the transfer roll Rt is removed. In order to return to the photoreceptor PR and collect it by the cleaner CL, the inter-image region voltage Vt2 having the same polarity as the toner charging polarity is applied to the transfer roll Rt by the inter-image region voltage applying means C3C2.

C3D: Fixing power supply circuit control means The fixing power supply circuit control means C3D controls the fixing power supply circuit Ed to control the fixing temperature of the fixing device F.
C4: Latent image forming device control means The latent image forming device control means C4 controls the latent image forming device ROS via the laser drive circuit DL to form an electrostatic latent image on the surface of the photoreceptor PR.

C5: Cumulative consumption measuring means The cumulative consumption measuring means C5 has cumulative consumption initializing means C5A, and measures the cumulative consumption which is the cumulative value of the developer consumption in the developing device G. The cumulative consumption measuring unit C5 of the first embodiment measures the cumulative consumption by measuring the number of pixels of the latent image written by the latent image forming apparatus ROS, that is, the cumulative number of pixels P1, which is a cumulative value of the number of pixels. Indirect measurement.
C5A: Cumulative consumption initialization means The cumulative consumption initialization means C5A initializes the cumulative pixel number P1 as an example of the cumulative consumption measured by the cumulative consumption measurement means C5.

C6: Developing Device Accumulated Driving Time Measuring Unit The developing device accumulated driving time measuring unit C6 includes an accumulated driving time initialization unit C6A, and measures the accumulated driving time of the developing device G. The developing device cumulative drive time measuring means C6 of Example 1 measures the cumulative drive time of the developing device G by measuring the cumulative driving time t1 of the developing roll Ga and the stirring members Gb and Gc of the developing device G.
C6A: Cumulative Drive Time Initializing Unit The cumulative drive time initializing unit C6A initializes the cumulative drive time t1 measured by the developing device cumulative drive time measuring unit C6.

C7: Degraded developer discriminating means The deteriorated developer discriminating means C7 includes an environment discriminating means C7A, an accumulated driving time discriminating means C7B, and a consumption speed discriminating means C7C, and the cumulative number of pixels as an example of the accumulated consumption amount. Based on P1 and the cumulative driving time t1 of the developing device G, it is determined whether or not the developer has been stirred and deteriorated in the developing device G for a long time in a state where the consumption of the developer is small. The deteriorated developer discriminating means of the first embodiment is such that the temperature and humidity environment at which the printer U is installed is low temperature and low humidity, and the accumulated drive time t1 has elapsed for a preset time or more, and the accumulated drive. When the developer consumption speed P1 / t1, which is the ratio of the cumulative developer consumption P1 with respect to the time t1, is equal to or less than a preset value, development is performed to the extent that it is necessary to perform an operation of discharging the deteriorated developer. It is determined that the deterioration of the agent has progressed.

C7A: Environment discriminating means The environment discriminating means C7A discriminates whether or not it is a low-humidity environment and a low-temperature environment discrimination value storage means C7A1 for storing a low-temperature environment discrimination value for discriminating whether or not it is a low-temperature environment. And a low humidity environment discrimination value storage means C7A2 for storing the low humidity environment discrimination value. The temperature and humidity environment in which the printer U is installed determines whether or not the developer is likely to deteriorate. The environment determination unit C7A according to the first embodiment determines whether the environment in which the printer U is installed is a low temperature / low humidity environment based on the detection results of the temperature sensor SN1 and the humidity sensor SN2. In Example 1, 20 [° C.] is used as the low-temperature environment discrimination value, and 7 [g / m ³ ] = 48 [% RH] is used as the low-humidity environment discrimination value. It is not limited to a value, and can be arbitrarily changed according to the design, specifications, use environment, and the like.

C7B: Cumulative driving time discriminating means The cumulative driving time discriminating means C7B stores the cumulative driving time discriminating value ta for discriminating whether or not the developing device G has been driven to such an extent that the deteriorated developer tends to increase. It has a discriminant value storage means C7B1, and discriminates whether or not the cumulative drive time t1 of the developing device G is equal to or greater than the cumulative drive time discriminant value ta. In the first embodiment, ta = 50 [hours] is used as the cumulative drive time determination value ta. However, specific numerical values are not limited to this value, and are determined according to the design, specifications, usage environment, and the like. It can be changed arbitrarily.

C7C: Consumption speed discriminating means The consumption speed discriminating means C7C includes a consumption speed discriminating value storage means C7C1 for storing a consumption speed discriminating value Na for discriminating whether or not the developer is stirred for a long time with a small amount of developer consumption. It is determined whether or not the consumption speed P1 / t1 is equal to or less than the consumption speed determination value Na. In the first embodiment, 10 [pixel / second] is used as the consumption speed discriminating value Na, but the specific numerical value is not limited to this value, and can be arbitrarily set according to the design, specifications, usage environment, and the like. It can be changed.

C8: Deteriorated developer discharging means The deteriorated developer discharging means C8 includes a deteriorated developer discharge setting determining means C8A, a deteriorated developer accumulation voltage application control means C8B, a discharge image formation control means C8C, and a deteriorated developer discharge. Voltage application control means C8D, and when the developer deterioration determination means C7 determines that the developer has deteriorated, the deteriorated developer is discharged from the visible image forming apparatus U2. The deteriorated developer discharging means C8 of Example 1 collects the deteriorated developer on the transfer roll Rt, transfers the collected deteriorated developer to the back surface of the medium S, discharges the medium S, and removes the deteriorated developer. By executing the dirt reduction mode as an example of the developer discharging operation for discharging outside the printer U, control is performed to discharge the deteriorated developer from the visible image forming apparatus U2.

C8A: Degraded developer discharge setting determination means The deteriorated developer discharge setting determination means C8A has a discharge setting storage means C8A1 and a discharge operation execution recommendation image display means C8A2, and is based on a user input from the operation unit UI. Thus, it is determined whether or not the setting for discharging the deteriorated developer, that is, the setting for automatically executing the dirt reduction mode is made.
C8A1: Discharge setting storage means The discharge setting storage means C8A1 stores whether or not to automatically execute the dirt reduction mode based on an input to the dirt reduction mode setting button UI4 of the operation unit UI.

C8A2: Discharge operation execution recommendation image display means The discharge operation execution recommendation image display means C8A2 determines that the developer has deteriorated by the developer deterioration determination means C7 and automatically executes the dirt reduction mode by the discharge setting storage means C8A1. When the setting is not made, an image that recommends execution of the dirt reduction mode is displayed on the display unit UI2, and the user is prompted to execute the dirt reduction mode. In the first embodiment, when the dirt reduction mode setting button UI4 is input during display of an image for which execution of the dirt reduction mode is recommended, the dirt reduction mode is executed, and an image for which execution of the dirt reduction mode is recommended is displayed. When the dirt reduction mode setting button UI4 is not input within a preset time, for example, within 30 seconds, the dirt reduction mode is set not to be executed.

C8B: Degraded Developer Accumulation Voltage Application Control Unit The degraded developer accumulation voltage application control unit C8B applies a voltage for accumulating the degraded developer to each member of the printer U when the dirt reduction mode is started. Apply. The deteriorated developer accumulation voltage application control means C8B of Example 1 outputs a signal to each of the means C3A to C3C of the power supply control means C3, and the charging voltage Vc of the charging roller CR, the developing voltage Vg of the developing roller Ga, and the transfer The transfer voltage Vt of the roller Rt is controlled to each voltage for collecting the deteriorated developer. In the first embodiment, negatively charged toner, that is, negatively charged toner is used as a developer, and −700 V is applied as an example of the charging voltage Vc and −600 V is applied as an example of the developing voltage Vg when the job is executed. Is set to Further, the transfer voltage Vt of the first embodiment is set so that the image transfer voltage Vt1 is applied, and +1 kV is set as an example of the image transfer voltage Vt1. In the dirt reduction mode, when collecting toner that has been deteriorated and has a polarity opposite to that of the normal polarity, that is, positive polarity, the charging voltage Vg is −700 V, which is the same as that during job execution, the development voltage Vg is 0 V, and the transfer voltage. As an example of the voltage Vt, −1.3 kV is applied as an example of the same voltage as the voltage Vt2 for the inter-image area, the photosensitive member PR and the developing device G are driven, and the positive polarity toner in the developing device G is transferred to the transfer roll Rt. It is set so as to be conveyed and adsorbed and accumulated on the surface of the transfer roll Rt. That is, in the accumulation process of the deteriorated developer in the dirt reduction mode, the development voltage Vg is turned off, and the transfer voltage Vt is set to be the reverse transfer voltage Vt2 having a reverse polarity to that during the job.

C8C: Ejection Image Formation Control Unit The ejection image formation control unit C8C outputs a control signal to the latent image forming device control unit C4 so as to form a preset ejection image. The discharge image formation control unit C8C according to the first exemplary embodiment indicates that the reverse polarity toner is transferred to the medium S when the reverse polarity toner accumulated on the transfer roll Rt is transferred to the back surface of the medium S. Therefore, an image is displayed to indicate that the reverse polarity toner has been transferred to the surface side of the medium S. As the image for discharging, for example, it is possible to use a document image having a content such as “this sheet is a cleaning sheet. Please discard it”.

C8D: Deteriorated developer discharge voltage application control means The deteriorated developer discharge voltage application control means C8D discharges accumulated reversely charged toner in the dirt reduction mode, and is a dirt removal paper as an example of the medium S, a so-called cleaning sheet. A voltage Vt for transferring the reversely charged toner is applied to each member of the printer U. The deteriorated developer discharge voltage application controller C8D according to the first exemplary embodiment performs control so that the image transfer voltage Vt1 similar to that at the time of image transfer at the time of job execution is applied to each member. In the first embodiment, as the cleaning sheet, plain paper with both sides not printed is used.

(Explanation of flowchart of Example 1)
(Explanation of flow chart of back surface dirt reduction mode control process)
FIG. 6 is an explanatory diagram of a flowchart of the backside dirt reduction mode control process of the image forming apparatus according to the first embodiment.
The processes in the flowchart of FIG. 6, so-called flowcharts, so-called step processes, are performed according to a program stored in the ROM or the like of the printer U. This process is other various processes of the printer U, for example, measurement of the accumulated drive time t1, which is the time during which each member of the developing device G is driven during job execution, and the accumulated value of the number of pixels printed in the job. This is executed in parallel with the measurement of the cumulative pixel number P1. The cumulative driving time t1 is measured when the driving of the developing roll Ga of the developing device G is started, and when the driving of the developing roll Ga is stopped, the cumulative driving time t1 is measured. In addition, the measurement of the cumulative pixel number P1 only accumulates the number of pixels written by the latent image forming apparatus ROS, and therefore, illustration and detailed description are omitted for the sake of simplicity. .

The flowchart shown in FIG. 6 is started when the printer U is powered on.
In ST1 of FIG. 6, it is determined whether or not the job is started by receiving print data or the like. If no (N), ST1 is repeated, and if yes (Y), the process proceeds to ST2.
In ST2, it is determined whether or not the environment is a low temperature environment, that is, whether or not the environmental temperature detected by the temperature sensor SN1 is 20 ° C. or less, which is a low temperature environment determination value. If yes (Y), the process proceeds to ST3. If no (N), the process proceeds to ST4.
In ST3, it is determined whether or not the environment is a low humidity environment, that is, whether or not the environmental humidity detected by the humidity sensor SN2 is 48% RH or less, which is a low humidity environment determination value. If no (N), the process proceeds to ST4, and if yes (Y), the process proceeds to ST10.

In ST4, it is determined whether or not the cumulative driving time t1 of the developing device G is equal to or longer than the cumulative driving time determination value ta. If yes (Y), the process proceeds to ST5, and, if no (N), the process proceeds to ST10.
In ST5, it is determined whether or not the cumulative number of pixels P1 / the cumulative driving time t1, that is, whether or not the developer consumption speed P1 / t1 is equal to or less than the consumption speed determination value Na. If yes (Y), the process proceeds to ST6, and if no (N), the process proceeds to ST10.
In ST6, it is determined whether or not the setting for automatically executing the dirt reduction mode is made. If no (N), the process proceeds to ST7, and if yes (Y), the process proceeds to ST9.
In ST7, an image recommending execution of the dirt reduction mode is displayed on the display unit UI2. Then, the process proceeds to ST8.

In ST8, it is determined whether or not an input for executing the dirt reduction mode is input from the operation unit UI. If yes (Y), the process proceeds to ST9, and if no (N), that is, if a preset time elapses after no image is displayed, the process proceeds to ST10.
In ST9, a stain reducing process for collecting and discharging the deteriorated developer shown in a subroutine of FIG. 7 described later is executed, and the process proceeds to ST10.
In ST10, it is determined whether or not the job is finished. If yes (Y), the process returns to ST1, and if no (N), the process returns to ST2.

(Explanation of dirt reduction processing flowchart)
FIG. 7 is a flowchart of the dirt reduction process of the first embodiment, and is an explanatory diagram of the subroutine of ST9 in FIG.
In ST21 of FIG. 7, the following processes (1) to (4) are executed, and the process proceeds to ST22.
(1) A job being executed is interrupted.
(2) The photosensitive member PR and the developing device G are driven.
(3) A reverse transfer voltage, that is, an inter-image region voltage Vt2 is applied to the transfer roll Rt.
(4) A charging voltage Vc is applied to the charging roller CR.
In ST22, it is determined whether or not it is time to feed the cleaning sheet. If no (N), ST22 is repeated, and if yes (Y), the process proceeds to ST23.
In ST23, the cleaning sheet is fed, and the process proceeds to ST24.

In ST24, it is determined whether or not it is time to form a paper discharge image. If no (N), ST24 is repeated, and if yes (Y), the process proceeds to ST25.
In ST25, the following processes (1) and (2) are executed, and the process proceeds to ST26.
(1) The latent image forming apparatus ROS is driven to form a latent image of a paper discharge image.
(2) In order to develop the latent image of the paper discharge image, the same development voltage Vg as that at the time of the job is applied to the developing roll Ga of the developing device G.
In ST26, it is determined whether or not the developed paper discharge image and the cleaning sheet have entered the transfer area Q3, that is, the so-called transfer timing. If no (N), ST26 is repeated, and if yes (Y), the process proceeds to ST27.

In ST27, an image for image transfer Vt1 for transferring the image to be discharged on the surface of the photoreceptor PR to the surface of the cleaning sheet and transferring the reverse transfer toner accumulated on the surface of the transfer roll Rt to the back surface of the cleaning sheet is transferred to the transfer roll Rt. Apply to. Then, the process proceeds to ST28.
In ST28, it is determined whether or not the trailing edge of the cleaning sheet has passed through the transfer region Q3. If no (N), ST28 is repeated, and if yes (Y), the process proceeds to ST29.
In ST29, the following processes (1) to (3) are executed. Then, the dirt reduction process of FIG. 7 is terminated, and the process returns to the flowchart of FIG.
(1) The accumulated driving time t1 of the developing device G is initialized to 0, so-called reset.
(2) The cumulative pixel number P1 is initialized to 0, so-called reset.
(3) Restart the suspended job.

(Operation of Example 1)
FIG. 8 is an explanatory diagram illustrating an example of transfer voltage control during an image forming operation in the printer U according to the first exemplary embodiment.
2, 3, and 8, in the printer U according to the first embodiment having the above-described configuration, when a job is started, an image on the surface of the photoreceptor PR, that is, a toner image is transferred to the surface of the medium S. In this case, a voltage Vt1 for image transfer is applied to the transfer roll Rt, and the toner on the surface of the photoreceptor PR is transferred to the medium S side. In the inter-image area, an inter-image area voltage Vt2 having a polarity opposite to that of the image transfer voltage Vt1 is applied.

FIG. 9 is an explanatory diagram of the operation of the first embodiment, FIG. 9A is an explanatory diagram of a state where the deteriorated developer is accumulated on the transfer roll, and FIG. 9B is a diagram where the deteriorated developer accumulated on the transfer roll is transferred to the cleaning sheet. It is explanatory drawing of the state performed.
In ST2 to ST8, FIG. 8, and FIG. 9 in FIG. 6, it is not a low-temperature and low-humidity environment, the cumulative drive time t1 is equal to or greater than the cumulative drive time determination value ta, and the consumption speed P1 / t1 is equal to or less than the consumption speed determination value Na. When the execution of the dirt reduction mode is set or input, the dirt reduction mode for discharging the deteriorated reversely charged toner and reducing the dirt on the medium S is started. In the dirt reduction mode, first, as shown in FIG. 9A, the surface of the photoconductor PR is charged with a reverse polarity to the reversely charged toner, and an interimage voltage Vt2 having a reverse polarity to the reversely charged toner is applied to the transfer roll Rt. Thus, the reversely charged toner that has moved from the inside of the developing device G to the surface of the photoconductor PR is accumulated and accumulated on the surface of the transfer roll Rt.

FIG. 10 is an explanatory diagram of the cleaning sheet of Example 1, FIG. 10A is an explanatory diagram of the surface of the discharged cleaning sheet, and FIG. 10B is an explanatory diagram of the back surface of the discharged cleaning sheet.
In the dirt reduction mode of the first embodiment, as the cleaning sheet Sc passes through the transfer region Q3, as shown in FIG. 9B, the image transfer voltage Vt1 having the same polarity as the reversely charged toner is applied to the transfer roll Rt. The reversely charged toner that has been applied and accumulated and accumulated on the transfer roll Rt is transferred to the back surface of the cleaning sheet Sc, fixed, and discharged. At this time, in Example 1, as shown in FIG. 10, the surface of the discharged cleaning sheet Sc is displayed as a cleaning sheet, and the reversely charged toner transferred from the transfer roll Rt is displayed on the back surface. Is attached. In Example 1, as shown in FIG. 10B, the transfer roll Rt is transferred to the cleaning sheet Sc by rotating it a plurality of times, and the strips Sc1 to Sc3 are formed on the back surface of the cleaning sheet Sc by the reversely charged toner. Printed. Therefore, compared with the case where the rotation speed of the transfer roll Rt is small, the reversely charged toner is less likely to remain on the surface of the transfer roll Rt, and the reversely charged toner is more reliably transferred to the cleaning sheet Sc.

Therefore, in the printer U according to the first exemplary embodiment, reversely charged toner that easily increases with time due to stirring in the developing device G and causes image quality defects and contamination of the medium S during normal image formation is transferred to the cleaning sheet Sc. Discharged outside the machine. In particular, in the first embodiment, the dirt reduction mode is executed when the consumption speed P1 / t1 is equal to or less than the consumption speed determination value Na.
As an example in which the consumption speed P1 / t1 is equal to or less than the consumption speed determination value Na, a case of mass printing of “postcard” will be described as an example. The “postcard” has a relatively thick paper thickness and the fixing temperature tends to decrease. Therefore, it is necessary to print with a wide interimage area so that the fixing temperature does not decrease too much. At this time, the developing device G is driven even in the inter-image region, and the developer in the developing device G is continuously stirred and is subjected to a load, so-called stress, in a state where image printing is not performed. When the image printed on the postcard is a relatively low-density image such as “address”, less toner is consumed. Therefore, in this case, the amount of toner consumed with respect to the cumulative driving time of the developing device G is extremely reduced as compared with the case of normal use in which text is printed on plain paper, and the consumption speed is reduced. When the consumption speed decreases, the toner is excessively stirred without being used. As a result, the toner is likely to be deteriorated due to excessive stress than usual, and the charged state of the toner is changed from the normal charged state, and the charge amount is decreased or charged to the opposite polarity. Therefore, in the first embodiment, when the consumption speed P1 / t1 is equal to or less than the consumption speed determination value Na, it is determined and estimated that the deteriorated toner has increased, and the dirt reduction mode is executed. Discharged. Thereby, compared with the case where the reversely charged toner is not discharged, the image quality deterioration and the contamination of the medium S due to the reversely charged toner are reduced.

  In Embodiment 1, the transfer residual toner adhering to the surface of the photoconductor PR that has passed through the transfer region Q3 during job execution is collected by the cleaner CL and reused by the developing device G. That is, the transfer residual toner subjected to stress due to discharge or rubbing in the development area Q2, the transfer area Q3, the cleaning blade 42, etc. is reused, compared with the case where the transfer residual toner is not reused. The developed toner G tends to increase in deteriorated toner over time. When the transfer residual toner conveyed to the developing device G is excessively agitated, it easily deteriorates. Correspondingly, in the printer U of the first embodiment, when the cumulative driving time t1 of the developing device G is equal to or greater than the cumulative driving time determination value ta, the consumption speed P1 / t1 is equal to or less than the consumption speed determination value Na. In addition, the dirt reduction mode is executed. Therefore, compared to the case where the dirt reduction mode is executed even when the accumulated driving time t1 is relatively short and not much deteriorated toner, the printing speed, that is, a reduction in productivity and waste due to the execution of the dirt reduction mode. Operation has been reduced.

Further, when the environmental temperature is high or the environmental humidity is high, the toner tends to be more deteriorated and deteriorated during the stirring than in a low temperature / low humidity environment. On the other hand, in the printer U according to the first embodiment, the dirt reduction mode is executed in a case other than the low temperature / low humidity environment. Therefore, even in low-temperature and low-humidity environments where toner deterioration is relatively unlikely, the productivity reduction and wasteful operations caused by executing the dirt reduction mode are reduced compared to the case where the dirt reduction mode is executed. Yes.
Further, in the printer U according to the first embodiment, it is possible to select automatic execution, manual execution, or non-execution of the dirt reduction mode in accordance with user input, and the image quality and productivity required by the user can be selected. Depending on the above, the dirt reduction mode is executed or not executed.

  Furthermore, in Example 1, when the reversely charged toner is transferred to the back surface of the cleaning sheet Sc, an indication that it is the cleaning sheet Sc is printed on the front surface side, so that the user can easily recognize that it is a cleaning sheet. ing. Accordingly, the use of the cleaning sheet Sc by mistake is reduced as compared with the case where no display is made, and the cleaning sheet Sc is easily and reliably removed.

(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 (H08) of the present invention are exemplified below.
(H01) In the above embodiment, the printer is illustrated as an example of the image forming apparatus. However, the present invention is not limited to this configuration, and the image forming apparatus such as a copying machine, a facsimile machine, or a multifunction machine having a plurality or all of these functions. It is applicable to. Further, although a monochromatic, so-called monochrome image forming apparatus has been exemplified, the present invention can also be applied to a multicolor, so-called color image forming apparatus.

(H02) In the above embodiment, the transfer device constituted by the transfer roll Rt is exemplified as the transfer device. However, the transfer device is not limited to this configuration, and the intermediate transfer member and the toner image on the photosensitive member are transferred to the intermediate transfer member. A transfer device including a primary transfer member for primary transfer and a secondary transfer member for secondary transfer of the toner image on the intermediate transfer member to the sheet may be used.
(H03) In the above-described embodiment, the configuration in which the developer recovered by the cleaner CL is reused in the developing device G is illustrated. However, the present invention is not limited to this configuration, and the developer recovered by the cleaner CL is used in the developing device G. Instead, it is also possible to collect in a collection box or the like.

(H04) In the above-described embodiments, the specific numerical values exemplified as the voltage, the discriminant value, etc., and the positive / negative polarity, that is, + − etc., can be appropriately changed according to the design, specifications, and the like. For example, in the embodiment, when collecting toner charged to + polarity, 0V is applied as the development voltage Vg, but a two-component developer composed of toner charged to -polarity and a carrier charged to + polarity is used. In this case, in order to prevent the carrier from moving to the image carrier, Vg can be set to Vg = −450 V instead of 0 V, for example.

(H05) In the embodiment, the condition for determining whether or not to execute the dirt reduction mode is not limited to the condition exemplified in the embodiment, and it is possible to add more conditions or reduce the conditions. is there. For example, it may be possible to add a condition for determining whether the type of medium used at the time of the job is a medium having a long inter-image area.
(H06) In the above-described embodiment, the configuration in which the display indicating that it is a cleaning sheet is exemplified on the surface of the cleaning sheet Sc. However, such a display is desirable, but the display may be omitted. .

(H07) In the above embodiment, as a method for discharging the deteriorated developer, a configuration in which the developer is transferred to the cleaning sheet and discharged to the outside of the apparatus is exemplified. However, the present invention is not limited to this configuration. For example, a cleaner is provided on the transfer roll Rt. When the contamination reduction mode is started, the reversely charged toner is discharged from the developing device G, moved to the transfer roll Rt, and collected by the cleaner. The cleaner of the transfer roll Rt can be configured to be separated from the transfer roll Rt in normal times and to be in contact with the transfer roll Rt in the dirt reduction mode.
(H08) In the above embodiment, the cumulative consumption of developer is measured using the cumulative number of pixels. However, the present invention is not limited to this configuration. For example, the consumption is calculated based on the number of printed sheets, the supply amount of developer, and the like. It is also possible to measure.

FIG. 1 is a perspective view of the image forming apparatus according to the first exemplary embodiment. FIG. 2 is a longitudinal sectional view of the image forming apparatus according to the first embodiment. FIG. 3 is an enlarged view of a main part of the toner image forming apparatus portion of FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a block diagram of the control unit of the image forming apparatus according to the first exemplary embodiment of the present invention. FIG. 6 is an explanatory diagram of a flowchart of the backside dirt reduction mode control process of the image forming apparatus according to the first embodiment. FIG. 7 is a flowchart of the dirt reduction process of the first embodiment, and is an explanatory diagram of the subroutine of ST9 in FIG. FIG. 8 is an explanatory diagram illustrating an example of transfer voltage control during an image forming operation in the printer U according to the first exemplary embodiment. FIG. 9 is an explanatory diagram of the operation of the first embodiment, FIG. 9A is an explanatory diagram of a state where the deteriorated developer is accumulated on the transfer roll, and FIG. 9B is a diagram where the deteriorated developer accumulated on the transfer roll is transferred to the cleaning sheet. It is explanatory drawing of the state performed. FIG. 10 is an explanatory diagram of the cleaning sheet of Example 1, FIG. 10A is an explanatory diagram of the surface of the discharged cleaning sheet, and FIG. 10B is an explanatory diagram of the back surface of the discharged cleaning sheet.

Explanation of symbols

43 ... Residual developer conveying member,
C5 ... Cumulative consumption measuring means,
C6: Developing device cumulative drive time measuring means,
C7: developer deterioration determining means,
C7A ... environment discrimination means,
C7B: Cumulative driving time discriminating means,
C8: Degraded developer discharging means,
CL ... cleaner
G ... Developer,
P1 ... Cumulative consumption
PR: Image carrier,
ROS ... latent image forming device,
Rt ... transfer device,
S ... medium,
ST2 to ST5 ... developer deterioration determination step,
ST21 to ST29 ... deteriorated developer discharging step,
t1 ... Cumulative driving time,
ta: Cumulative driving time discriminating value,
U: Image forming apparatus,
U1 ... Image forming apparatus main body,
U2: Visible image forming apparatus.

Claims (6)

A rotating image carrier, a latent image forming device that forms a latent image on the surface of the image carrier, a developing unit that develops the latent image formed on the surface of the image carrier into a visible image, and the image carrier A visible image forming apparatus comprising: a transfer device that applies a transfer voltage for transferring a visible image on the surface to the medium and transfers the visible image on the surface of the image carrier to the medium;
A cumulative consumption measuring means for measuring cumulative consumption which is a cumulative value of developer consumption;
A developer cumulative drive time measuring means for measuring the cumulative drive time of the developer;
Developer deterioration determination means for determining whether or not the developer has been deteriorated by being stirred in the developer for a long time in a state where the consumption of the developer is small, based on the cumulative consumption and the cumulative driving time of the developer. When,
A deteriorated developer discharging means for discharging the deteriorated developer from the visible image forming apparatus when the developer deterioration determining means determines that the developer has deteriorated;
An image forming apparatus comprising: When the developer deterioration determining means determines that the developer has deteriorated, transfer with a polarity opposite to the transfer voltage for transferring the visible image on the surface of the image carrier to the medium without conveying the medium After applying the voltage to accumulate the deteriorated developer on the surface of the transfer device, the transfer device applies the transfer voltage for transferring the visible image on the surface of the image carrier to the medium while transporting the medium. The deteriorated developer discharging means for discharging the deteriorated developer out of the apparatus by executing a deteriorated developer discharging operation for transferring the deteriorated developer accumulated on the surface to the medium;
The image forming apparatus according to claim 1, further comprising: A cleaner for collecting and cleaning the residual developer attached to the surface of the image carrier after the visible image is transferred to the medium;
A residual developer transport member that transports the residual developer collected by the cleaner to the developer;
The image forming apparatus according to claim 1, further comprising: Cumulative driving time determination means for determining whether or not the cumulative driving time of the developing unit has reached or exceeded a preset cumulative driving time determination value;
When the cumulative drive time becomes equal to or greater than the cumulative drive time determination value, the developer is used for a long time in a state where the developer consumption is low, based on the cumulative consumption and the cumulative drive time of the developer. The developer deterioration determining means for determining whether or not the toner has been deteriorated by stirring,
The image forming apparatus according to claim 1, further comprising: Based on the environment in which the image forming apparatus main body is installed, an environment determination unit that determines whether or not the developer is likely to deteriorate.
When it is determined by the environment determining means that the developer is likely to deteriorate, the developer is long in a state where the consumption of the developer is small based on the cumulative consumption and the cumulative driving time of the developing device. The developer deterioration determining means for determining whether or not the developer has been deteriorated by being stirred in the time developing device;
The image forming apparatus according to claim 1, further comprising: Cumulative consumption of developer consumed when developing the latent image on the surface of the rotating image carrier into a visible image, and a developer for developing the latent image formed on the surface of the image carrier into a visible image A developer deterioration determining step for determining whether or not the developer has been deteriorated by being stirred in the developing device for a long time in a state where the consumption of the developer is low, based on the cumulative driving time;
A deteriorated developer discharging step of discharging the deteriorated developer when the developer deterioration determining means determines that the developer has deteriorated;
A method for discharging a deteriorated developer, comprising: