JP2021051208A - Image forming apparatus and image forming method - Google Patents

Abstract

To simplify discarding processing of discarding a deteriorated developer, and reduce the time until printing is started.SOLUTION: An image forming apparatus has: an image carrier; a charging device that charges a surface of the image carrier; a developer carrier that attaches developer to the image carrier; a driving unit that rotates the image carrier; and a discarding processing unit Pr2 that applies a DC charging voltage VC of 0 V to the charging device, rotates the image carrier for a predetermined time and stops the image carrier, and applies a DC developing voltage VD of 0 V to the developer carrier for a predetermined time from the start of rotation of the image carrier to perform developer discarding processing. A special discarding sequence is not required to be provided, and the discarding processing can be simplified.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image forming apparatus and an image forming method.

Conventionally, an image forming device such as a printer, a copying machine, a facsimile, or a multifunction device, for example, an electrophotographic printer, is provided with an image forming unit, an LED head, a transfer unit, a fixing device, and the like, and the image forming unit is provided with an image forming unit, an LED head, a transfer unit, and a fuser. , Photoreceptor drum, charging roller, developer, etc. are arranged.

In this type of printer, the surface of the photoconductor drum uniformly charged by the charging roller is exposed by the LED head to form an electrostatic latent image, and the electrostatic latent image is developed by the developing roller in the developing device. The toner image is formed by the transfer unit, the toner image is transferred to the paper by the transfer unit, and the toner image is fixed by the fixing device to form an image, and printing is performed.

The developer is arranged in the toner storage section of the image forming unit, and includes a developing roller, a supply roller, a developing blade, and the like. Toner as a developer supplied from the toner cartridge to the toner storage section is developed by the supply roller. It is supplied to the roller, the layer thickness is regulated by the developing blade, and the layer is thinned. At this time, the layer is charged by friction with the supply roller and the developing blade.

The toner that has not been used to develop the electrostatic latent image is collected in the toner storage, scraped from the developing roller by the feeding roller, and supplied to the developing roller again.

By the way, when printing is continuously performed, the toner that has not been used for developing the electrostatic latent image and forming the toner image is collected in the toner storage unit and then rubbed against the supply roller and the developing blade. As a result of repeating the above steps, the image quality is deteriorated because it is melted by frictional heat, aggregated and deteriorated.

Therefore, there is provided a printer that performs a disposal process when the toner deteriorates and the disposal condition is satisfied, and discards the deteriorated toner (see, for example, Patent Document 1).

JP-A-2015-4837

However, in the conventional printer, since it is necessary to provide a special disposal sequence for performing the disposal process, not only the disposal process becomes complicated but also the time until printing is started becomes long.

The present invention can solve the problems of the conventional printer, simplify the disposal process of discarding the deteriorated developer, and shorten the time until printing is started. And an image forming method is provided.

Therefore, in the image forming apparatus of the present invention, an image carrier, a charging device that charges the surface of the image carrier, a developer carrier that attaches a developer to the image carrier, and the image carrier. A DC charging voltage of 0 [V] is applied to the driving unit and the charging device to rotate the image carrier, and the image carrier is rotated for a predetermined time to stop the image carrier. It has a waste processing unit that applies a DC 0 [V] developing voltage to the developing agent carrier to dispose of the developing agent.

According to the present invention, in the image forming apparatus, an image carrier, a charging device that charges the surface of the image carrier, a developer carrier that attaches a developer to the image carrier, and the image carrier. A DC charging voltage of 0 [V] is applied to the driving unit and the charging device to rotate the image carrier, and the image carrier is rotated for a predetermined time to stop the image carrier. It has a waste processing unit that applies a DC 0 [V] developing voltage to the developing agent carrier to dispose of the developing agent.

In this case, in the disposal process, a direct current 0 [V] charging voltage is applied to the charging device, the image carrier is rotated for a predetermined time to be stopped, and then the rotation of the image carrier is started. Since a direct current 0 [V] development voltage is applied to the developer carrier for a predetermined time, it is not necessary to provide a special disposal sequence for performing the disposal process, and the disposal process can be simplified.

Further, since the disposal process is performed before the printing is started, the time until the printing is started can be shortened.

Further, since the surface potential of the image carrier is set to 0 [V] by applying a direct current 0 [V] charging voltage to the charging device, an image is formed in order to attach the deteriorated developer to the image carrier. It is not necessary to expose the carrier to set the surface potential of the image carrier to 0 [V].

Therefore, the life of the image carrier can be extended.

It is a control block diagram of the printer in the 1st Embodiment of this invention. It is the schematic of the printer in the 1st Embodiment of this invention. It is a flowchart which shows the operation of the image formation unit in 1st Embodiment of this invention. It is a time chart which shows the operation of the image formation unit when the disposal condition in the 1st Embodiment of this invention is not satisfied. It is a time chart which shows the operation of the image formation unit when the disposal condition in the 1st Embodiment of this invention is satisfied. It is a flowchart which shows the operation of the image formation unit when the disposal condition in a comparative example is satisfied. It is a time chart which shows the operation of the image formation unit when the disposal condition in the comparative example is satisfied. It is the schematic of the printer in the 2nd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, an electrophotographic color printer as an image forming apparatus will be described.

FIG. 2 is a schematic view of a printer according to the first embodiment of the present invention.

In the figure, 10 is a printer, Cs is a housing of the printer 10, an operation panel Pn is arranged above the housing Cs, and a paper cassette 11 as a medium accommodating portion is arranged below the housing Cs. Paper P as a medium is placed on the stacker St1 of the paper feed cassette 11. A paper feeding mechanism 12 for separating and feeding paper P one by one is arranged adjacent to the front end of the paper feed cassette 11.

The paper feed mechanism 12 includes a paper feed roller 13 and a separation device (not shown), and the paper P separated one by one by the paper feed mechanism 12 and fed into the medium transport path Rt1 is fed to the transport roller pair 14. After that, it is supplied to the image forming units 16Bk, 16Y, 16M, 16C as an image forming unit for forming an image of each color of black, yellow, magenta, and cyan.

Each of the image forming units 16Bk, 16Y, 16M, 16C is detachably arranged with respect to the main body of the printer 10, that is, the device main body Bd, and includes a photoconductor drum 31 and the like as an image carrier. Further, the LED head 22 as an exposure device is arranged so as to face each of the photoconductor drums 31 in correspondence with the respective image forming units 16Bk, 16Y, 16M, 16C.

The image forming units 16Bk, 16Y, 16M, 16C are formed below the toner cartridge 29 as a developer accommodating portion for accommodating toner as a developer and the toner cartridge 29, and stores the toner supplied from the toner cartridge 29. Toner storage unit 30, the photoconductor drum 31, a charging roller 32 as a charging device that uniformly charges the surface of the photoconductor drum 31, a developing roller 33 as a developer carrier for holding toner, and the toner storage. A supply roller 34 as a developer supply member that supplies the toner in the portion 30 to the development roller 33, a development blade 35 as a developer layer regulating member that uniformly thins the toner supplied on the development roller 33, and a photosensitive member. A first cleaning member 36 or the like for removing toner on the body drum 31 is provided. The developer is composed of the developing roller 33, the supply roller 34, and the developing blade 35.

In the present embodiment, the toner supplied from the toner cartridge 29 to the toner storage unit 30 is supplied to the developing roller 33 by the supply roller 34, the layer thickness is regulated by the developing blade 35, and the layer is thinned on the developing roller 33. At this time, the toner is charged to a negative polarity by friction with the supply roller 34 and the developing blade 35.

The photoconductor drum 31 is rotated in the direction of the arrow by an ID motor (drum motor) 76 (FIG. 1) as a driving unit for image formation, which will be described later, and the surface is made uniform by the charging roller 32 as the rotation occurs. Is charged and exposed by the LED head 22, an electrostatic latent image as a latent image is formed on the surface. The toner on the developing roller 33 is electrostatically adhered to the electrostatic latent image, and a toner image as a developing agent image is formed on the photoconductor drum 31.

Further, the photoconductor drum 31 is composed of a conductive support processed into a cylindrical shape and a photosensitive layer portion formed by applying a photosensitive layer on the conductive support, and the photosensitive layer portion is conductive. It is formed by laminating a blocking layer, a charge generating layer, and a charge transporting layer in order from the support side.

In the present embodiment, the photosensitive layer portion is coated so that the thickness of the charge transport layer is about 18 [μm] (see JP-A-2009-288672). An eddy current film thickness meter "LH-200J" manufactured by Kett Science Institute Headquarters is used for measuring the film thickness.

Then, the transfer unit u is arranged below each of the image forming units 16Bk, 16Y, 16M, 16C. The transfer unit u includes a transfer belt 17 as a belt member movably stretched by a drive roller r1 as a first roller, a driven roller r2 as a second roller, a drive roller r1 and a driven roller r2. A transfer roller 21 and a cleaning device 25 as a first transfer member are rotatably arranged so as to face the photoconductor drum 31 with the transfer belt 17 interposed therebetween. The cleaning device 25 includes a second cleaning member 27 that scrapes and removes the toner adhering to the transfer belt 17, and a waste toner storage chamber 28 that stores the scraped toner as waste toner.

When a belt motor (not shown) as a drive unit for running the belt is driven, the drive roller r1 is rotated in the direction of the arrow, and the transfer belt 17 is moved in the direction of the arrow.

The paper P supplied to the image forming unit 16Bk is conveyed as the transfer belt 17 travels, passes between each photoconductor drum 31 and each transfer roller 21, and each transfer roller 21 forms each image. The black, yellow, magenta, and cyan toner images formed on the photoconductor drums 31 in the units 16Bk, 16Y, 16M, and 16C are sequentially superimposed on the paper P and transferred to form a color toner image. The toner remaining on the photoconductor drum 31 after the toner image is transferred is scraped off by the first cleaning member 36, and is used as waste toner in a waste toner recovery chamber (not shown) as a waste developer recovery chamber. Will be collected.

Subsequently, the paper P is sent to a fixing device 18 as a fixing device, and is heated in the fixing device 18 by a heating roller 19 as a first fixing member having a halogen lamp (not shown) as a heating member inside. , The pressure is applied by the pressure roller 20 as the second fixing member, the color toner image is fixed, and the color image is formed. Then, the paper P discharged from the fixing device 18 is discharged to the outside of the apparatus main body Bd by the discharge roller pair 24, and is loaded on the stacker St2 formed on the top of the housing Cs.

In the present embodiment, the toner of each color is formed of a polyester resin, a colorant, a charge control agent, a mold release agent, or the like, and an external additive (hydrophobic silica) is added. Further, in the present embodiment, the toners of each color are formed by a pulverization method, have a pulverized shape, and have an average particle size of 8 [μm], but can also be formed by a production method such as a polymerization method.

Organic pigments such as carbon black, pigment yellow, pigment magenta, and pigment cyan are used as colorants for black, yellow, magenta, and cyan, but some transparent pigments are used to mix the colors. To.

The developing roller 33 is composed of a metal shaft and an elastic layer formed on the outer periphery of the metal shaft. As the elastic layer, urethane rubber having semiconductivity and a rubber hardness of 70 [°] (Asker C) is used.

The supply roller 34 is composed of a metal shaft and a foam layer formed on the outer periphery of the metal shaft. As the foam layer, a silicon foam body having a hardness of 50 [°] (Asker F) is used.

Next, the control device of the printer 10 will be described.

FIG. 1 is a control block diagram of a printer according to the first embodiment of the present invention.

In the figure, 10 is a printer, 50 is a control unit, 51 is a host computer as an information input device and a higher-level device, 52 is an interface unit, 55 is a memory as a storage device, and the memory 55 is a memory. A ROM 56 as a first storage unit and a RAM 57 as a second storage unit are provided.

The control unit 50 includes a CPU, an input / output port, a timer, and the like (not shown), receives a print job from the host computer 51 via the interface unit 52, and prints the print job on paper P based on print data and control commands. An image is formed and printed.

Therefore, the control unit 50 performs various processes based on the program recorded in the ROM 56. In addition to the program, the ROM 56 records a print duty ratio threshold table, various set values, and the like, which will be described later. Further, in the RAM 57, various control data are temporarily recorded in addition to the image data generated based on the print data and for performing normal printing. The RAM 57 is used as a working memory when the CPU performs an operation.

Further, the control unit 50 includes a disposal condition establishment determination processing unit Pr1, a disposal processing unit Pr2, a process control processing unit Pr3, a printing processing unit Pr4, and the like.

The disposal condition establishment determination processing unit Pr1 performs the disposal condition establishment determination processing, and determines whether or not the disposal condition for discarding the deteriorated toner is satisfied.

The disposal unit Pr2 performs a disposal process and discards the deteriorated toner. Therefore, the disposal unit Pr2 applies a direct current 0 [V] charging voltage VC to the charging roller 32 (FIG. 2), rotates the photoconductor drum 31 by τ2 for a predetermined time, stops the photoconductor, and then stops the photoconductor. A direct current 0 [V] development voltage VD is applied to the τ1 developing roller 33 for a predetermined time after the rotation of the drum 31 is started, and the toner adhering to the photoconductor drum 31 is removed by the cleaning member 36.

The process control processing unit Pr3 performs process control processing, drives the ID motor 76, rotates the photoconductor drum 31, the developing roller 33, the supply roller 34, etc., and charges the photoconductor drum 31 with the charging roller 32. ..

The printing processing unit Pr4 performs printing processing, drives the LED head 22, forms an electrostatic latent image on the surface of the photoconductor drum 31, develops the electrostatic latent image, and forms a toner image. The toner image is transferred to the paper P.

Then, in the figure, 61 is a medium sensor (not shown) that detects the paper P conveyed on the medium transport path Rt1, a temperature sensor (not shown) that detects the temperature that is the printing environment of the printer 10, and a humidity sensor (not shown) that detects the humidity. Sensors such as, Pn includes an operation unit 63 including switches and keys for the operator to input instructions to the printer 10, and a display unit 64 including an LED screen for displaying the status of the printer 10. The operation panel 67 provided is a process control unit that controls the image forming process.

Further, 68 is a development voltage VD of +30 [V] or more and +150 [V] or less, or a development voltage VD of 0 [V], or -30 [V] or more, independently of each of the development rollers 33. The development voltage control unit 71, which applies a development voltage VD of −400 [V] or less, is independently supplied to each of the supply rollers 34 with a supply voltage VS of 0 [V] or −50 [V] or more. The layer forming / supply voltage control unit 72 that applies the supply voltage VS of −700 [V] or less independently applies the charging voltage VC of 0 [V] or −700 [V] to each of the charging rollers 32. The charging voltage control unit 73, which applies a charging voltage VC of V] or more and -1500 [V] or less, independently to each of the transfer rollers 21 is +1000 [V] or more and +5000 [V]. The transfer voltage control unit 74 that applies the following transfer voltage VT independently drives each of the LED heads 22, and the exposure control unit 75 that exposes the photoconductor drum 31 independently drives the ID motor 76. This is a motor control unit that rotates the photoconductor drum 31, the developing roller 33, and the supply roller 34.

In the present embodiment, the developing voltage VD, the supply voltage VS, the charging voltage VC, and the transfer voltage VT are all DC voltages.

Gears (not shown) are arranged at one end of the photoconductor drum 31, the developing roller 33, and the supply roller 34, and the gears are meshed with each other. Therefore, when the ID motor 76 is driven, the rotation of the ID motor 76 is transmitted to the photoconductor drum 31 and transmitted to the developing roller 33 and the supply roller 34.

By the way, when printing is continuously performed in the printer 10, the toner not used for developing the electrostatic latent image is collected in the toner storage unit 30 and then rubbed against the supply roller 34 and the developing blade 35. As a result of repeating the above steps, the image quality is deteriorated because it is melted by frictional heat, aggregated and deteriorated.

Therefore, in the present embodiment, when the toner deteriorates and the disposal condition is satisfied, the disposal process is performed by the disposal processing unit Pr2 for each print job transmitted from the host computer 51, resulting in a predetermined amount of deterioration. Toner is being discarded.

Therefore, the disposal condition establishment determination processing unit Pr1 monitors the printing duty ratio δ of each printing job and the printing environment of temperature and humidity in the image forming units 16Bk, 16Y, 16M, 16C, and the toner deteriorates. It is determined whether or not the disposal condition is satisfied, and if the disposal condition is satisfied, the disposal processing unit Pr2 performs the disposal treatment and discards the deteriorated toner.

Next, the operation of the image forming units 16Bk, 16Y, 16M, 16C will be described. Since the operations of the image forming units 16Bk, 16Y, 16M, and 16C are basically the same, the operation of the image forming unit 16Bk will be described.

FIG. 3 is a flowchart showing the operation of the image forming unit according to the first embodiment of the present invention, and FIG. 4 shows the operation of the image forming unit when the disposal condition according to the first embodiment of the present invention is not satisfied. The time chart shown, FIG. 5, is a time chart showing the operation of the image forming unit when the disposal condition in the first embodiment of the present invention is satisfied. In this case, the ID motor 76 (FIG. 1) and the LED head 22 (FIG. 2) are driven on and stopped off, and the charging voltage VC and supply voltage VS become on and negative (-) values. Off to 0 [V], development voltage VD on to negative (-) or positive (+) value, off to 0 [V], transfer voltage VT on to positive (+) It becomes the value of, and becomes 0 [V] when it is off.

First, the control unit 50 acquires the print job transmitted from the host computer 51 and calculates the print duty ratio δ of the print job.

By the way, when the print duty of the print job is low, the toner in the toner storage unit 30 is supplied by the supply roller because it is used to develop the electrostatic latent image to form the toner image and the amount of toner consumed is small. By repeating friction with 34 and the developing blade 35, it melts due to frictional heat and aggregates and deteriorates.

On the other hand, when the print duty of the print job is high, the toner in the toner storage unit 30 is used because the amount of toner used to develop the electrostatic latent image to form the toner image and is consumed is large. , The repetition of friction with the supply roller 34 and the developing blade 35 is small, and the deterioration does not occur.

Therefore, the disposal condition establishment determination processing unit Pr1 acquires the number of prints N and the number of dots Dt formed at the time of printing based on the print data for each print job, and sets the number of dots Dt with respect to the number of prints N as the print duty ratio. δ
δ = Dt / N
The temperature and humidity detected by the sensors 61 are read, the print duty ratio threshold table of ROM 56 is referred to, the threshold δth corresponding to the temperature and humidity is read, and the print duty ratio δ is equal to or less than the threshold δth. Whether or not the disposal condition is satisfied is determined. The threshold value δth can be set to a predetermined value, for example, 3 [%], which is set in advance regardless of the temperature and humidity.

When the disposal condition is not satisfied, the process control processing unit Pr3 drives the ID motor 76 at the timing t1 to rotate the photoconductor drum 31, the developing roller 33, the supply roller 34, etc., as shown in FIG. At the same time, a charging voltage VC of −1000 [V] is applied to the charging roller 32 to charge the surface of the photoconductor drum 31. Since the printing process for the previous printing job is completed at the timing t1, the surface potential of the photoconductor drum 31 is set to 0 [V], and the photoconductor is charged with the application of the charging voltage VC. The drum 31 is charged to a negative polarity.

Further, the process control processing unit Pr3 applies a development voltage VD of +100 [V] to the developing roller 33 at the timing t1. As a result, a development voltage VD having a polarity opposite to the charging polarity of the toner, that is, a positive polarity is applied to the developing roller 33, so that the toner charged to a negative polarity is held by the developing roller 33 and is exposed to light. It is not attached to the body drum 31.

Here, assuming that the distance between the charging roller 32 and the developing roller 33 on the outer peripheral surface of the photoconductor drum 31 is 23 [mm], the photoconductor is subjected to a predetermined time τ1 from timings t1 to t2. The drum 31 is rotated and the outer peripheral surface moves by 23 [mm]. The ID motor 76 is rotated so that when the outer peripheral surface of the photoconductor drum 31 moves by 23 [mm], the portion of the photoconductor drum 31 facing the charging roller 32 reaches the position facing the developing roller 33. The speed and the rotation speed of the photoconductor drum 31 are set.

Subsequently, the process control processing unit Pr3 applies a development voltage VD of −200 [V] to the development roller 33, a supply voltage VS of −300 [V] to the supply roller 34, and a transfer roller at timing t2. A transfer voltage VT of +2000 [V] is applied to 21.

Then, the process control processing unit Pr3 rotates the developing roller 33 and the supply roller 34 by two turns, respectively. As a result, the toner on the developing roller 33 is stably charged.

Subsequently, the print processing unit Pr4 starts the print process at the timing t3, reads the image data from the RAM 57 by the timing t4, and drives the LED head 22 based on the image data. As a result, the photoconductor drum 31 is exposed, and an electrostatic latent image is formed on the surface of the photoconductor drum 31.

At this time, since the development voltage VD having a negative polarity is applied to the developing roller 33 and the supply voltage VS having a negative polarity is applied to the supply roller 34, the toner is developed by the supply roller 34 during the timings t4 to t5. It is attached to the roller 33 and is attached to the photoconductor drum 31 from the developing roller 33 to form a toner image. Further, since the transfer voltage VT having a positive polarity is applied to the transfer roller 21, the toner image of the photoconductor drum 31 is transferred to the paper P.

Then, the print processing unit Pr4 stops the application of the transfer voltage VT to the transfer roller 21 at the timing t5, and ends the printing process.

Subsequently, the process control processing unit Pr3 stops the application of the charging voltage VC to the charging roller 32 at the timing t6. As a result, the surface potential of the photoconductor drum 31 becomes 0 [V].

Further, the process control processing unit Pr3 stops the ID motor 76 at the timing t7 to stop the photoconductor drum 31, the developing roller 33, the supply roller 34, etc., and applies the developing voltage VD to the developing roller 33. And the application of the supply voltage VS to the supply roller 34 is stopped.

The predetermined time τ2 from the timings t6 to t7 is equal to the predetermined time τ1. Therefore, while the charging voltage VC applied to the charging roller 32 is set to 0 [V], the photoconductor drum 31 is rotated to move the outer peripheral surface by 23 [mm], and the photoconductor drum 31 and the charging roller 32 The facing portion reaches a position facing the developing roller 33.

On the other hand, when the disposal condition is satisfied, the process control processing unit Pr3 drives the ID motor 76 at the timing t1 to rotate the photoconductor drum 31, the developing roller 33, the supply roller 34, and the like, as shown in FIG. At the same time, a charging voltage VC of −1000 [V] is applied to the charging roller 32 to charge the surface of the photoconductor drum 31. Since the printing process for the previous printing job is completed at the timing t1, the surface potential of the photoconductor drum 31 is set to 0 [V], and the photoconductor is charged with the application of the charging voltage VC. The drum 31 is charged to a negative polarity.

Then, the waste processing unit Pr2 starts the disposal process at the timing t1, and applies a development voltage VD of 0 [V] to the developing roller 33 by the timing t2.

At this time, since the surface potential of the photoconductor drum 31 is 0 [V], no electrostatic force acts on the toner charged to a negative polarity on the developing roller 33, and the developing roller 33 is subjected to the van der Waals force. The above-mentioned predetermined amount of toner, in the present embodiment, an amount of about 50% of the toner on the developing roller 33 is adhered to the photoconductor drum 31. It is known that the amount of toner adhered to the photoconductor drum 31 by the Van der Waals force varies depending on the surface roughness of the developing roller 33 and the photoconductor drum 31, but is approximately 50 [%]. ..

The toner adhering to the photoconductor drum 31 is scraped off and removed by the first cleaning member 36 as the photoconductor drum 31 rotates. Therefore, the deteriorated toner can be discarded.

In order to dispose of the deteriorated toner, the toner adhering to the photoconductor drum 31 is transferred to the transfer belt 17 and scraped off by the second cleaning member 27 to be used as waste toner in the waste toner storage chamber 28. It can also be accommodated. Further, the toner adhering to the photoconductor drum 31 is scraped and removed by the first cleaning member 36, transferred to the transfer belt 17, and scraped by the second cleaning member 27 as waste toner. It can also be accommodated in the waste toner accommodating chamber 28.

Then, while the predetermined time τ1 from the timing t1 to t2 when the development voltage VD of 0 [V] is applied to the developing roller 33 elapses, the photoconductor drum 31 is rotated and the outer peripheral surface moves by 23 [mm]. Then, the portion of the photoconductor drum 31 facing the charging roller 32 reaches a position facing the developing roller 33.

The disposal unit Pr2 applies a development voltage VD having a negative polarity, for example, -30 [V], to the developing roller 33 to increase the amount of deteriorated toner to be discarded, or to increase the amount of deteriorated toner to be discarded, or to positively apply the developing roller 33. By applying a developing voltage VD having a polarity of, for example, +30 [V], the amount of deteriorated toner discarded can be reduced. When the amount of deteriorated toner discarded is increased, the amount of toner adhering to the photoconductor drum 31 is increased, which may cause cleaning failure by the first cleaning member 36 or the like. Therefore, it is preferable to apply a developing voltage VD of 0 [V] to the developing roller 33.

Subsequently, the process control processing unit Pr3 applies a development voltage VD of −200 [V] to the development roller 33, a supply voltage VS of −300 [V] to the supply roller 34, and a transfer roller at timing t2. A transfer voltage VT of +2000 [V] is applied to 21.

Then, the process control processing unit Pr3 rotates the developing roller 33 and the supply roller 34 by two turns, respectively. As a result, the toner on the developing roller 33 is stably charged.

Subsequently, the print processing unit Pr4 starts the print process at the timing t3, reads the image data from the RAM 57 by the timing t4, and drives the LED head 22 based on the image data. As a result, the photoconductor drum 31 is exposed, and an electrostatic latent image is formed on the surface of the photoconductor drum 31.

At this time, since the development voltage VD having a negative polarity is applied to the developing roller 33 and the supply voltage VS having a negative polarity is applied to the supply roller 34, the toner is developed by the supply roller 34 during the timings t4 to t5. It is attached to the roller 33 and is attached to the photoconductor drum 31 from the developing roller 33 to form a toner image. Further, since the transfer voltage VT having a positive polarity is applied to the transfer roller 21, the toner image of the photoconductor drum 31 is transferred to the paper P.

Then, the print processing unit Pr4 stops the application of the transfer voltage VT to the transfer roller 21 at the timing t5, and ends the printing process.

Subsequently, the waste processing unit Pr2 stops the application of the charging voltage VC to the charging roller 32 at the timing t6, and sets the charging voltage VC applied to the charging roller 32 to 0 [V]. As a result, the surface potential of the photoconductor drum 31 becomes 0 [V].

The predetermined time τ2 from the timings t6 to t7 is equal to the predetermined time τ1. Therefore, while the charging voltage VC applied to the charging roller 32 is set to 0 [V], the photoconductor drum 31 is rotated to move the outer peripheral surface by 23 [mm], and the photoconductor drum 31 and the charging roller 32 The facing portion reaches a position facing the developing roller 33.

Further, the process control processing unit Pr3 stops the ID motor 76 at the timing t7 to stop the photoconductor drum 31, the developing roller 33, the supply roller 34, etc., and applies the developing voltage VD to the developing roller 33. The application of the supply voltage VS to the supply roller 34 is stopped.

Next, the flowchart will be described.
Step S1 The control unit 50 acquires a print job.
Step S2 The disposal condition establishment determination processing unit Pr1 determines whether or not the disposal condition is satisfied. If the disposal condition is satisfied, the process proceeds to step S3, and if the disposal condition is not satisfied, the process proceeds to step S4.
Step S3 The waste processing unit Pr2 applies a developing voltage VD of 0 [V] to the developing roller 33.
Step S4 The process control processing unit Pr3 applies a developing voltage VD of +100 [V] to the developing roller 33.
Step S5 The print processing unit Pr4 performs a print process and ends the process.

As described above, in the present embodiment, the disposal processing unit Pr2 performs the disposal treatment, so that the charging voltage VC of 0 [V] is applied to the charging roller 32, and the photoconductor drum 31 is rotated by τ2 for a predetermined time. After being stopped, the developing voltage VD of τ1, 0 [V] is applied for a predetermined time after the rotation of the photoconductor drum 31 is started, and the toner adhering to the photoconductor drum 31 is the first. Since it is removed by the cleaning member 36, it is not necessary to provide a special disposal sequence for performing the disposal process, and the disposal process can be simplified.

Further, since the disposal process can be performed before the start of printing, the time until the start of printing can be shortened.

Further, since the surface potential of the photoconductor drum 31 is set to 0 [V] by applying a charging voltage VC of 0 [V] to the charging roller 32, in order to attach the deteriorated toner to the photoconductor drum 31. It is not necessary to expose the photoconductor drum 31 to set the surface potential of the photoconductor drum 31 to 0 [V].

Therefore, the life of the photoconductor drum 31 can be extended.

Next, a comparative example of the printer 10 will be described.

FIG. 6 is a flowchart showing the operation of the image forming unit in the comparative example, and FIG. 7 is a time chart showing the operation of the image forming unit when the disposal condition in the comparative example is satisfied. In this case, the ID motor 76 (FIG. 1) and the LED head 22 (FIG. 2) are driven on and stopped off, and the charging voltage VC and the supply voltage VS are turned on to negative (-) values. When it is off, it becomes 0 [V], when the development voltage VD becomes on, it becomes a negative (-) value or a positive (+) value, when it becomes off, it becomes 0 [V], and when the transfer voltage VT is on, it becomes positive (+). It becomes a value of +) and becomes 0 [V] when it is off.

First, the disposal condition establishment determination processing unit Pr1 of the control unit 50 acquires the print job transmitted from the host computer 51, calculates the print duty ratio δ of the print job, and detects the temperature and humidity by the sensors 61. Is read, the print duty ratio threshold table of ROM 56 is referred to, the threshold δth corresponding to temperature and humidity is read, and whether or not the disposal condition is satisfied is determined by whether or not the print duty ratio δ is equal to or less than the threshold δth.

When the disposal condition is satisfied, the process control processing unit Pr3 drives the ID motor 76 at the timing t11 to rotate the photoconductor drum 31, the developing roller 33, the supply roller 34, and the like, as shown in FIG. , A charging voltage VC of −1000 [V] is applied to the charging roller 32 to charge the surface of the photoconductor drum 31. Since the printing process of the previous printing job is completed at the timing t11, the surface potential of the photoconductor drum 31 is set to 0 [V], and the photoconductor drum 31 is applied with the charging voltage VC. 31 is charged to a negative polarity.

Further, the process control processing unit Pr3 applies a development voltage VD of +100 [V] to the developing roller 33 at the timing t11. As a result, the development voltage VD having a positive polarity is applied to the developing roller 33, so that the toner charged to the negative polarity is held by the developing roller 33 and is not adhered to the photoconductor drum 31.

Subsequently, the process control processing unit Pr3 applies a development voltage VD of −200 [V] to the developing roller 33 and a supply voltage VS of −300 [V] to the supply roller 34 at the timing t12.

Then, the process control processing unit Pr3 rotates the developing roller 33 and the supply roller 34 by two turns, respectively. As a result, the toner on the developing roller 33 is stably charged.

Next, the disposal processing unit Pr2 performs disposal processing, drives the LED head 22 between the timings t13 and t14, and lights all the LEDs of the LED head 22. As a result, the entire photoconductor drum 31 is exposed, and a solid electrostatic latent image is formed on the surface of the photoconductor drum 31. Along with this, the toner on the developing roller 33 is solidly adhered to the photoconductor drum 31, but since the transfer voltage VT is not applied to the transfer roller 21 during the timings t13 to t14, the photoconductor drum 31 is subjected to the toner. The adhered toner is scraped off and removed by the first cleaning member 36 as the photoconductor drum 31 rotates without being transferred to the paper P. In this way, the deteriorated toner is discarded.

Subsequently, the process control processing unit Pr3 rotates the developing roller 33 and the supply roller 34 by two turns each from the timings t14 to t15. As a result, the toner on the developing roller 33 is stably charged.

Next, the process control processing unit Pr3 applies a transfer voltage VT of +2000 [V] to the transfer roller 21 by the transfer voltage control unit 73.

Subsequently, the print processing unit Pr4 starts the print process at the timing t15, reads the image data from the RAM 57 by the timing t16, and drives the LED head 22 based on the image data. As a result, the photoconductor drum 31 is exposed, and an electrostatic latent image is formed on the surface of the photoconductor drum 31.

At this time, since the development voltage VD having a negative polarity is applied to the developing roller 33 and the supply voltage VS having a negative polarity is applied to the supply roller 34, the toner is supplied by the developing roller 34 from the timing t16 to t17. It is attached to 33 and is attached to the photoconductor drum 31 from the developing roller 33 to form a toner image. Further, since the transfer voltage VT having a positive polarity is applied to the transfer roller 21, the toner image of the photoconductor drum 31 is transferred to the paper P.

Then, the print processing unit Pr4 stops the application of the transfer voltage VT to the transfer roller 21 at the timing t17, and ends the printing process.

Subsequently, the process control processing unit Pr3 stops the ID motor 76 at the timing t18 to stop the photoconductor drum 31, the developing roller 33, the supply roller 34, and the like, and applies the charging voltage VC to the charging roller 32. The application of the development voltage VD to the developing roller 33 and the application of the supply voltage VS to the supply roller 34 are stopped. As a result, the surface potential of the photoconductor drum 31 becomes 0 [V].

Next, the flowchart will be described.
Step S11 The control unit 50 acquires a print job.
Step S12 The disposal condition establishment determination processing unit Pr1 determines whether or not the disposal condition is satisfied. If the disposal condition is satisfied, the process proceeds to step S13, and if the disposal condition is not satisfied, the process proceeds to step S14.
Step S13 The waste treatment unit Pr2 performs the waste treatment.
Step S14 The print processing unit Pr4 performs a print process and ends the process.

In the comparative example, as shown in FIG. 7, the LED head 22 is driven between the timings t13 and t14 in order to dispose of the deteriorated toner, and the photoconductor drum 31 is driven between the timings t14 and t15. Since the toner adhering to the LED is discarded, it is necessary to provide a special disposal sequence for performing the disposal process, which complicates the disposal process and increases the time until printing is started.

On the other hand, in the present embodiment, as shown in FIG. 5, the photoconductor drum is formed by applying a developing voltage VD of 0 [V] to the developing roller 33 between the timings t1 and t2. Since the toner is attached to 31 and the toner attached to the photoconductor drum 31 is discarded, it is not necessary to provide a special disposal sequence for performing the disposal process, and the disposal process can be simplified. , The time until printing is started can be shortened.

In the comparative example, the distance between the charging roller 32 and the developing roller 33 on the outer peripheral surface of the photoconductor drum 31 was 23 [mm], and the outer diameters of the charging roller 32 and the developing roller 33 were 13 [mm]. At this time, it is necessary to expose the photoconductor drum 31 between timings t13 and t14, and to rotate the developing roller 33 and the supply roller 34 by two turns between timings t14 and t15, so that timings t13 to t15 are required. The amount of movement L [mm] of the outer circumference of the photoconductor drum 31 between
L = 23+ (13π + 13π) x 2
≒ 23 + 163
≈186 [mm]
become. Further, when the peripheral speed of the photoconductor drum 31 is 180 [mm / s], the predetermined time τ3 from the timing t13 to t15 is
τ3 = 186/180
≈ 1.03 [s]
become.

That is, in the present embodiment, the time until the start of printing can be shortened by 1.03 [s].

In the present embodiment, the printer 10 of the direct transfer method in which the toner image of each color is directly transferred to the paper P is described. However, in the present invention, the toner image of each color is transferred to the intermediate transfer belt and intermediate transfer is performed. It can be applied to an intermediate transfer type printer in which a color toner image is formed on a belt and transferred to paper.

Next, a second embodiment of the present invention in which printing is performed by an intermediate transfer method will be described. The same reference numerals are given to those having the same structure as that of the first embodiment, and the effects of the same embodiment are used for the effects of the invention due to having the same structure.

FIG. 8 is a schematic view of the printer according to the second embodiment of the present invention.

In the figure, 10 is a printer as an image forming apparatus, 16Bk, 16Y, 16M, 16C is an image forming unit as an image forming unit for forming an image of each color of black, yellow, magenta and cyan, and u1 is a transfer unit. ..

The transfer unit u1 can travel freely by a drive roller R1 as a first roller, a driven roller R2 as a second roller, a backup roller R3 as a third roller, a drive roller R1, a driven roller R2, and a backup roller R3. As a first transfer member rotatably arranged so as to face an intermediate transfer belt 81 as an intermediate transfer member and a photoconductor drum 31 as an image carrier sandwiching the intermediate transfer belt 81. A transfer roller 21, a secondary transfer roller R4 and the like as a second transfer member rotatably arranged so as to face the backup roller R3 with the intermediate transfer belt 81 interposed therebetween are provided.

Toner images as developer images of each color formed on the photoconductor drum 31 in each image forming unit 16Bk, 16Y, 16M, 16C are sequentially superimposed and transferred to the intermediate transfer belt 81 as the intermediate transfer belt 81 runs. A color toner image is formed and transferred to paper as a medium (not shown).

In this case, in the disposal process, the transfer voltage VT applied to the transfer roller 21 is set to 0 [V], and the secondary transfer roller R4 is separated from the intermediate transfer belt 81. Then, the toner adhering to the photoconductor drum 31 is scraped off by a first cleaning member (not shown) arranged in the image forming units 16Bk, 16Y, 16M, 16C as the photoconductor drum 31 rotates. , Will be removed. Therefore, the deteriorated toner can be discarded.

The toner adhering to the photoconductor drum 31 is transferred to the intermediate transfer belt 81 and scraped off by a second cleaning member (not shown) arranged to face the intermediate transfer belt 81 to form waste toner. It can also be stored in a waste toner storage chamber (not shown). Further, the toner adhering to the photoconductor drum 31 is scraped and removed by the first cleaning member, transferred to the intermediate transfer belt 81, and scraped by the second cleaning member to be used as waste toner. It can also be accommodated in the waste toner accommodating chamber.

In each of the above-described embodiments, the disposal unit Pr2 applies a DC charging voltage VC of 0 [V] to the charging roller 32 during the timings t6 to t7 to perform the disposal processing, and the timings t1 to t2. Until then, a DC development voltage VD of 0 [V] is applied to the development roller 33, but at least one of the charging voltage VC and the development voltage VD is a DC voltage of 0 [V]. It is also possible to superimpose an AC voltage component on the component to generate it. In that case, the amplitude and frequency of the AC component are arbitrarily set.

Although the printer 10 is described in each of the above embodiments, the present invention can be applied to an image forming apparatus such as a copier, a facsimile, and a multifunction device.

The present invention is not limited to each of the above-described embodiments, and various modifications can be made based on the gist of the present invention, and these are not excluded from the scope of the present invention.

10 Printer 22 LED head 31 Photoreceptor drum 32 Charging roller 33 Developing roller 76 ID motor Pr2 Disposal processing unit

Claims (8)

(A) Image carrier and
(B) A charging device that charges the surface of the image carrier, and
(C) A developer carrier for adhering a developer to the image carrier and a developer
(D) A driving unit that rotates the image carrier and
(E) A direct current 0 [V] charging voltage is applied to the charging device, the image carrier is rotated for a predetermined time to stop, and then the image carrier starts to rotate for a predetermined time. An image forming apparatus comprising a disposal processing unit for applying a direct current 0 [V] developing voltage to a carrier to dispose of a developing agent. The image forming apparatus according to claim 1, wherein the disposal processing unit applies a charging voltage of 0 [V] to the charging device after the printing process by the printing processing unit is completed, and rotates the image carrier for the predetermined time. .. The predetermined time during which the image carrier is rotated after the printing process is completed is until the portion of the image carrier facing the charging device reaches a position facing the developer carrier as the image carrier rotates. The image forming apparatus according to claim 2, which is the time of the above. Before the printing process by the printing processing unit is started, the waste processing unit applies a developing voltage of 0 [V] to the developing agent carrier, rotates the image carrier for the predetermined time, and causes the image carrier to rotate. The image forming apparatus according to claim 2 or 3, wherein the adhering developer is removed by a cleaning member. During the predetermined time during which the image carrier is rotated before the printing process is started, the portion of the image carrier facing the charging device reaches a position facing the developer carrier as the image carrier rotates. The image forming apparatus according to claim 4, which is the time required for the printing. (A) When the disposal conditions for disposing of the deteriorated developer are satisfied, the disposal unit performs the disposal process.
(B) When the disposal condition is not satisfied, a charging voltage of 0 [V] is applied to the charging device, the image carrier is rotated for a predetermined time, and then the developer carrier is charged with the polarity of charge of the developer. The image forming apparatus according to any one of claims 1 to 3, wherein a developing voltage having a polarity opposite to that of the above is applied. The image forming apparatus according to claim 1, wherein the disposal unit removes the developer adhering to the image carrier with a cleaning member. A method for forming an image of an image carrier, a charging device for charging the surface of the image carrier, a developer carrier for adhering a developer to the image carrier, and an image forming apparatus having a driving unit for rotating the image carrier. In
(A) A direct current 0 [V] charging voltage is applied to the charging device, and the image carrier is rotated for a predetermined time to stop.
(B) An image forming method characterized by applying a direct current 0 [V] developing voltage to the developing agent carrier for a predetermined time after starting the rotation of the image carrier to dispose of the developing agent. ..

Images