JP3088373B2 - Photosensitive drum cleaning mechanism and printing apparatus using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive drum cleaning mechanism and a printing apparatus using the same, and more particularly to a cleaning mechanism for cleaning a photosensitive drum using an electrophotographic method and a printing apparatus using the same.

[0002]

2. Description of the Related Art In general, in a printing apparatus, especially a copying machine or a printing apparatus which requires a large amount and high speed printing output, a printing apparatus using an electrophotographic system is widely used. In an electrophotographic printing apparatus provided with a cleaning mechanism to prevent the filming phenomenon of the photosensitive drum, the photosensitive drum is always cleaned by a constant operation using a brush, a roller using blade electric force, or the like. It is common to have. Here, a printing apparatus using continuous paper as a medium will be described as a basic example of such a printing apparatus.

FIG. 2 is a schematic diagram showing an example of a basic configuration of an electrophotographic printing apparatus, and FIG. 3 is a schematic diagram including a control system of a cleaning mechanism of an electrophotographic section.

Referring to FIGS. 2 and 3, in a printing apparatus using an electrophotographic method, a printing paper 1 set in a paper feeding unit 2 is transported by a tractor unit 3 while an electrophotographic printing unit 4 The image of the toner 12 on the photosensitive drum 11 formed by the process is transferred, and the fixing unit 5 forms a permanent image on a sheet. After this step, the sheets 1 are sent to the stacker 6 and stacked while being folded and aligned.

[0005] In the electrophotographic process in the printing section 4, the surface of the rotating photosensitive drum 11 is uniformly charged by the charger 13, and is exposed to laser light 15 emitted from the laser oscillator 14, and the surface of the photosensitive drum 11 is exposed. A latent image such as a character is formed on the image.

In the developing device 16, the toner 12 is put on the latent image portion on the surface of the photosensitive drum 11. The developing device 16 contains a developer composed of a toner and a carrier, and is provided with a TC sensor 17 for monitoring the amount of the toner 12 in the developer. According to the output of the TC sensor 17, when the toner 12 in the developer is consumed for printing by a certain amount or more,
The toner supply motor 18 is driven to add the toner 12, and the toner 12 is supplied from the toner hopper 19 into the developing device 16.
Supply.

The toner 12, which has become a visible image on the photosensitive drum 11, is transferred onto the sheet 1 by a transfer unit 20 provided in the tractor unit 3. The residual toner 12 that has not been completely transferred is scraped off and cleaned by a cleaning brush 21, and the potential of the surface of the photosensitive drum 11 is reduced to zero by an erase lamp 22. This process is repeated to form an image.

In the tractor section 3, the continuous paper 1 on which the perforated holes have been formed is set on a pin tractor section 23 which is adjusted to the same interval as the width of the paper, and the printing section 4 forms a visible image on the paper 1. The resulting toner 12 is loaded and sent to the fixing unit 5.

In the fixing section 5, the toner 12 image on the sheet 1 is heated and pressed by the heater roll 31 to be fixed.
An oil impregnated member 32 is applied to the heater roll 31, and the oil impregnated member 32 is applied to the heater roll 31 while being supplied with oil by a pump of an oil tank 34, and is cleaned. Further, the oil impregnated member 32 sequentially provides new parts by the winding motor 33.

In the stacker 6, the printing paper 1 discharged from the fixing section 5 is folded and stacked on a stacker table 36 while being cooled by a cooling blower 35.

A printing apparatus using an electrophotographic system has a print density switching mechanism in which an operator adjusts a print density by using a switch or the like. The switching of the print density is performed by changing the surface potential value of the photosensitive drum 11 in the printing unit 4 or the bias value of the mag roll of the developing unit 16 so as to increase the amount of the toner 12 placed on the latent image portion on the photosensitive drum 11. It is done by reducing.

Next, the operation of cleaning the photosensitive drum 11 in the printing unit 4 will be described.

On the surface of the photosensitive drum 11, a developing device 16 places a toner 12 on a latent image portion. The transfer unit 20 in the tractor unit 3 transfers the toner 12 that has become a visible image on the photosensitive drum 11 to the paper 1. In the rear stroke of the transfer device 20, there is a cleaning brush 21, which is driven to rotate by a brush motor 25. The cleaning brush 21 is constantly driven during the rotation operation of the photosensitive drum 11. A hose 27 is connected to the cleaning brush 21 via a cyclone 28 to a blower 26. A collection container 29 is provided below the cyclone 28. The blower 26 also operates during the rotation of the photosensitive drum 11, and performs suction. The residual toner 12 that has not been completely transferred by the transfer device 20 on the photosensitive drum 11 is scraped off by the cleaning brush 21, and the scraped toner 12 is removed.
Is sucked into a hose 27 by suction of a blower 26, sieved by a cyclone 28, and deposited in a collection container 29.

Here, as means for solving the problem such as filming of the photosensitive drum 11, Japanese Patent Application Laid-Open No.
The means using a cleaning brush proposed in Japanese Patent No. 2767 has been described. However, the means for transferring to a roller pressed against a photosensitive drum by using an electric force proposed in Japanese Patent Application Laid-Open No. 58-017472, -297450
There is also a means for scraping with a blade proposed in Japanese Patent Application Laid-Open Publication No. HEI 10-115,873.

[0015]

In the above-described conventional printing apparatus, the driving of the cleaning brush and the blower is controlled at a constant rotation amount regardless of the printing density. Therefore, when the printing density is extremely high, the toner cannot be completely transferred to the paper, and the amount of residual toner on the photosensitive drum is large. Would.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks and calculate the printing density suitable for the paper size even when various paper sizes are used, and vary the rotation speed of the cleaning brush according to the printing density. And a photosensitive drum cleaning mechanism for varying the suction force of a blower, and a printing apparatus using the same.

[0017]

According to the present invention, there is provided a photosensitive drum cleaning mechanism for cleaning a photosensitive drum in an electrophotographic system.
A cleaning mechanism for cleaning the photosensitive drum;
Cleaning brush for scraping off residual toner
The toner scraped with a cleaning brush is passed through a cyclone.
A valve for adjusting the suction force of the blower to be sucked and collected,
Calculate the printing density from the toner supply amount and the width of the printing paper.
The rotation speed of the cleaning brush and the valve
And a control unit for determining the suction force based on the aperture ratio of the control unit .

Further, the photosensitive drum cleaning mechanism of the present invention includes a print number counter for monitoring the number of prints,
And print density determination unit determines print density and a supply amount of the width and the toner supply motor of the paper, said from the print density
Comprises the control unit and a cleaning mechanism driving unit for driving said cleaning brush valve.

Further, the photosensitive drum cleaning mechanism of the present invention provides a sheet for inputting sheet width data which is an output value of a sheet size detecting section for reading a sheet size from a widthwise movement position of a pin tractor section of a tractor section for conveying a sheet. A size input unit, and a supply amount setting value of the toner supply motor at a standard print density serving as a reference for the paper width from the paper width data
A paper width based reference printing density when the toner supply amount calculating unit for calculating the said and operation of the toner supply motor printed sheets counted
A toner supply motor monitoring unit that obtains a supply amount from the printer unit, and a print density calculated from the value obtained by the toner supply motor monitoring unit and the value calculated by the toner supply amount calculation unit at the time of the reference print density for each paper width. And a print density output unit that outputs the print density calculated by the print density arithmetic unit to the cleaning mechanism drive unit.

Further, the photosensitive drum cleaning mechanism of the present invention further comprises a print density input section for inputting the print density calculated by the print density determining section, a rotation speed of a cleaning brush, an opening ratio of a valve, and the like based on the print density. From a cleaning operation unit that calculates the value of the cleaning operation unit, a brush motor operation instruction unit that drives the brush motor based on the value calculated by the cleaning operation unit, and a valve operation instruction unit that drives the valve motor from the value calculated by the cleaning operation unit. And a cleaning mechanism driving unit.

Furthermore, the photosensitive drum cleaning method of the present invention, when the paper is set to the tractor unit, the print density of the control unit the sheet width data (W) of the paper sheet size detecting unit that read the tractor unit When the printing is started and the printing is started, in the printing density determining unit, the paper width data (W) is input to the paper size inputting unit, and the toner width calculating unit for the standard printing density per paper width calculates the paper width. The reference set value (P0) of the number of pages for driving the toner supply motor, which is the toner supply amount at the standard print density in the data (W), is calculated, and the reference set value (P0) is a standard value for 15-inch wide paper. When the printing density of 3% is performed, the toner consumption per page is 60 mg. When the toner is replenished every time 3000 mg is consumed, the toner supply motor is driven once every 50 pages. P0 = 50 × (15 / W), and at the same time, the toner supply motor monitoring unit, which monitors the drive of the toner supply motor, calculates the drive interval of the toner supply motor that is actually operating from the print sheet count unit. When the number of printed pages (P1) is obtained, the print density is calculated by the print density calculation unit for comparison with the reference set value (P0) at the standard print density of 3% calculated by the toner supply amount calculation unit at the standard print density for each paper width. The print density (D) is calculated as D = 3 × P0
/ P1 and the printing density (D) calculated by the printing density calculation unit are output from the printing density output unit to the cleaning mechanism driving unit.
The print density input unit inputs the print density (D) calculated by the print density determination unit, and the cleaning calculation unit drives the cleaning brush that cleans the photosensitive drum based on the input print density (D). The operation amount (O) of the valve motor that drives the valve that controls the suction force of the blower is calculated based on the drive rotation speed (T) of the brush motor and the opening ratio, and the brush operation amount calculated by the cleaning operation unit is calculated. The brush motor operation command unit drives the brush motor based on the motor rotation speed (T), and the valve operation command unit drives the valve motor based on the valve motor operation amount (O) calculated by the cleaning operation unit. When the print density (D) of the print data calculated by the print density determination unit is high, the brush motor is driven to increase the rotation speed of the cleaning brush. At the same time, the valve motor is driven in order to increase the suction force of the cleaning brush unit by closing the valve. In the cleaning operation unit, the driving speed (T) of the brush motor is calculated from the print density (D) by T = Calculated by A × D / 3 (A is the number of rotations at 3% printing density), and the operation amount (O) of the valve motor is O2 = B from the movement amount O2 from the initial position and the position O1 before the change. × D
(B is a constant coefficient of the valve motor operation amount) O = O2-O1
Is calculated.

Further, in the printing apparatus of the present invention, a paper supply section for supplying paper, a tractor section for transporting the paper, a printing section for forming characters and images, and a printing section on the paper by the printing section. 2. The photosensitive drum according to claim 1, wherein the printing unit includes an electrophotographic method for cleaning the photosensitive drum, wherein the printing unit includes a fixing unit that fixes the discharged toner and a stacker unit that accumulates discharged paper. 3. A cleaning mechanism is provided.

[0023]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an outline of an operation of cleaning the electrophotographic section in one embodiment of the present invention. The configuration, functions, operations, and the like of the entire printing apparatus using continuous paper as a printing medium are the same as those in the conventional example shown in FIG. 2 using the electrophotographic method as an example, and a description thereof will be omitted below.

Referring to FIGS. 1 and 2, 1 is a printing sheet, 3 is a tractor section, 4 is a printing section, 11 is a photosensitive drum, 12 is toner, 16 is a developing device, 18 is a toner supply motor, 20 Is a transfer device, 21 is a cleaning brush, 23
Is a pin tractor unit, 24 is a paper size detecting unit, 25 is a brush motor, 26 is a blower, 27 is a hose, 28 is a cyclone, 29 is a collection container, 38 is a valve, 39 is a valve motor, 41 is a control unit, 50 Is the print count section,
Reference numeral 60 denotes a cleaning mechanism driving unit, 61 denotes a print density input unit, 62 denotes a cleaning operation unit, 63 denotes a brush motor operation instruction unit, 64 denotes a valve operation instruction unit, 70 denotes a print density determination unit, 71 denotes a paper size input unit, and 72 denotes a paper size input unit. Denotes a toner supply motor monitoring unit, 73 denotes a toner supply amount calculation unit at a reference print density for each sheet, 74 denotes a print density calculation unit, and 75 denotes a print density output unit.

The printing section 4 includes a photosensitive drum 11 as an image holding member. A developing device 16 is provided on the photosensitive drum 11, and the toner 1 is applied to a portion where the latent image is formed by the laser beam 15.
Put 2 on. The developing device 16 has a toner supply motor 18 that is fed into the toner 12 in the developer, and outputs the information of the driving time interval of the toner supply motor 18 (or driving time) in print density determination Priority determination unit 70.

The tractor section 3 has a pin tractor section 23 on which the paper 1 is set. Paper 1 of tractor section 3
A transfer unit 20 is provided at a position corresponding to the back surface of the photoconductive drum 11 to transfer the toner 12 on the photosensitive drum 11 to the paper 1.

The tractor unit 3 includes a paper size detection unit 24
There are outputs from the moving position in the width direction of the pin tractor 23 the value read the paper size to print density determination Priority determination <br/> portion 70 of the control unit 41.

A cleaning brush 21 is provided in a rear stroke of the tractor section 3 and is driven to rotate by a brush motor 25. The cleaning brush 21 is connected to a blower 26 via a cyclone 28 by a hose 27. A collection container 29 is provided below the cyclone 28. A valve 38 is provided between the cyclone 28 and the cleaning brush 21, and a valve motor 39 is provided.
, The valve in the valve 38 is driven.

The control section 41 has a printed number counter section 50 for monitoring the number of printed sheets, a print density determining section 70, and a cleaning mechanism driving section 60. Print density determination unit 7
0 indicates a paper size input unit 71 for inputting an output value of the paper size detection unit 24, and a toner supply motor 18 at a standard print density as a reference for the paper width based on the input value read by the paper size input unit 71. Drive interval (or drive time)
A toner supply amount calculating unit 73 for calculating a set value at a reference print density for each sheet width;
Toner supply motor monitoring unit 72 which monitors the operation of the printer and obtains the drive interval (or drive time) from the printed sheet count unit 50
A print density calculator 74 for calculating a print density from a value obtained by the toner supply motor monitor 72 and a value calculated by the toner supply amount calculator for reference print density by paper width 73; And a print density output unit 75 that outputs the print density calculated in the above to the cleaning mechanism drive unit 60.

The cleaning mechanism drive unit 60 includes a print density input unit 61 for inputting the print density calculated by the print density determination unit 70, and the rotation speed of the cleaning brush 21 and the valve 38 based on the input value of the print density input unit 61. A cleaning operation unit 62 for calculating an aperture ratio of the brush, a brush motor operation instruction unit 63 for driving the brush motor 25 based on the value calculated by the cleaning operation unit 62, and a cleaning operation unit 6.
There is a valve operation command section 64 for driving the valve motor 39 from the value calculated in 2.

When the paper 1 is set on the tractor section 3 of the printing apparatus, the paper size detection section 24 of the tractor section 3 sends the read paper width data (W) to the print density determination section 70 of the control section 41. Output. When printing is started, the print density determination unit 70 of the control unit 41 inputs the paper width data (W) to the paper size input unit 71, and the paper supply data calculation unit 73 for the standard print density by paper width calculates the paper width data (W). (W) toner supply amount at standard printing density (toner supply motor 1
The reference set value (P0), which is the number of pages at 8 drive intervals, is calculated. The standard set value (P0) is that when a standard printing density of 3% is performed on 15-inch wide paper, the toner consumption per page is 60 mg and the toner is replenished every time 3000 mg is consumed. Since the supply motor 18 is driven, it is calculated by P0 = 50 × (15 / W).

At the same time, the toner supply motor monitoring unit 72, which monitors the driving of the toner supply motor 18 in the developing unit 16, outputs a print interval of the drive interval of the toner supply motor that is actually operating from the print number counting unit 50. When the number of pages (P1) is obtained, the toner supply amount calculation unit 7 at the reference print density for each paper width
The reference setting value (P
0) Print density (D)
Is calculated. The print density (D) is calculated by D = 3 × P0 / P1. The print density (D) calculated by the print density calculation unit 74 is output from the print density output unit 75 to the cleaning mechanism drive unit 60.

The cleaning mechanism driving section 60 of the control section 41
Then, the print density (D) calculated by the print density determination unit 70
Is input by the print density input unit 61. Based on the input print density (D), the cleaning operation unit 62 suctions the blower 26 based on the driving speed (T) of the brush motor 25 driving the cleaning brush 21 for cleaning the photosensitive drum 11 and the aperture ratio. The operation amount (O) of the valve motor 39 for driving the valve 38 for adjusting the force is calculated. The brush motor operation command unit 63 drives the brush motor 25 based on the drive rotation speed (T) of the brush motor 25 calculated by the cleaning operation unit 62. Further, the valve operation command unit 64 drives the valve motor 39 based on the operation amount (O) of the valve motor 39 calculated by the cleaning operation unit 62.

When the print density (D) of the print data calculated by the print density determination unit 70 is high, the brush motor 25 is driven so as to increase the rotation speed of the cleaning brush 21. At the same time, the valve 38 is closed to increase the suction force of the cleaning brush 21 by closing the valve 38.
9 is driven.

In the cleaning operation unit 62, the number of rotations (T) of the brush motor 25 is calculated from the printing density (D) by T = A ×
Calculated as D / 3 (A is the number of rotations at 3% printing density).
Further, the operation amount (O) of the valve motor 39 is obtained from the movement amount O2 from the initial position and the position O1 before the change, O2 = B × D
(B is a constant coefficient of the valve motor operation amount) O = O2-O1
Is calculated.

In the above description, as an example, the information of the paper width size (W) is added to the pin tractor section 2 of the tractor section 3.
3, the size information of the stacker 6 and the paper feeding unit 2 and the print data information from the host device can be used.

Although the print density is calculated based on the drive time of the toner supply motor 18, the print density can be calculated from the input values from the TC sensor and the toner mark sensor. There is also a method of analyzing and judging the image signal read in the main scanning direction and the sub-scanning direction.

[0039]

As described above, according to the present invention,
Judgment of the printing density, and by controlling the rotation speed of the cleaning brush and the suction force of the blower in accordance with the level of the printing density, remove the filming that occurs without cleaning and the dirt caused by the accumulated toner falling. The effect of prevention can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an outline of an operation of cleaning an electrophotographic unit according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating an example of a basic configuration of an electrophotographic printing apparatus.

FIG. 3 is a schematic diagram including a control system of a cleaning mechanism of a conventional electrophotographic printing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Paper 2 Paper feed part 3 Tractor part 4 Printing part 5 Fixing part 6 Stacker 11 Photosensitive drum 12 Toner 13 Charger 14 Laser oscillator 15 Laser light 16 Developing device 17 TC sensor 18 Toner supply motor 19 Toner hopper 20 Transfer device 21 Cleaning brush 22 Erase Lamp 23 Pin Tractor 24 Paper Size Detector 25 Brush Motor 26 Blower 27 Hose 28 Cyclone 29 Collection Container 31 Heater Roll 32 Oil Impregnated Member 33 Winding Motor 34 Oil Tank 35 Cooling Blower 36 Stacker Table 38 Valve 39 Valve Motor 41 control section 50 printed sheet count section 60 cleaning mechanism drive section 61 print density input section 62 cleaning operation section 63 brush motor operation command section 64 valve operation command section 70 print density determination Part 71 paper size input unit 72 the toner supply motor monitoring unit 73 when the sheet width by the reference printing density toner supply amount calculating unit 74 print density calculation unit 75 print density output section

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-241380 (JP, A) JP-A-3-174181 (JP, A) JP-A-57-116378 (JP, A) JP-A 8- 26542 (JP, A) JP-A-9-146316 (JP, A) JP-A-9-146317 (JP, A) Japanese Utility Model Application No. Sho 57-150851 (JP, U) (58) Fields investigated (Int. Cl. ^7, DB name) G03G 21/10 - 21/12 G03G 21/00 370 - 540 G03G 21/14

Claims (6)

(57) [Claims] 1. A method for cleaning a photosensitive drum in an electrophotographic system.
A cleaning mechanism for performing the cleaning on the photosensitive drum.
A cleaning brush for scraping residual toner,
The toner scraped off by the cleaning brush through the cyclone
A valve for adjusting the suction power of the blower for suction and recovery.
Print density is calculated from the amount of toner supplied and the width of the paper to be printed.
And the rotation speed of the cleaning brush and the valve
A photosensitive drum cleaning mechanism comprising: a control unit that determines a suction force based on an aperture ratio . 2. A print number counter for monitoring the number of prints, a width of the sheet and a supply amount of a toner supply motor.
A print density determination unit for determining a print density from the print density;
Photosensitive drum cleaning mechanism according to claim 1, characterized by comprising the control unit and a cleaning mechanism driving unit for driving said valve and the cleaning brush from. 3. A paper size input unit for inputting paper width data which is an output value of a paper size detection unit for reading a paper size from a width direction movement position of a pin tractor unit of a tractor unit for transporting paper, and the paper width data. From the toner supply motor at the standard print density, which is the reference for the paper width
The toner supply amount calculation unit at the reference print density for each sheet width for calculating the set value, the operation of the toner supply motor, and the number of printed sheets
A toner supply motor monitoring unit that obtains a supply amount from a counting unit; and a print density is calculated from a value obtained by the toner supply motor monitoring unit and a value calculated by the toner supply amount calculation unit at a reference print density for each paper width. 3. The print density determination section, comprising: a print density calculation section for performing the printing; and a print density output section for outputting the print density calculated by the print density calculation section to the cleaning mechanism drive section. The photosensitive drum cleaning mechanism according to the above. A print density input unit for inputting the print density calculated by the print density determination unit; a cleaning operation unit for calculating a rotation speed of a cleaning brush and an opening ratio of a valve from the print density; The cleaning mechanism drive unit comprising: a brush motor operation command unit that drives a brush motor based on a value calculated by a cleaning calculation unit; and a valve operation command unit that drives a valve motor based on a value calculated by the cleaning calculation unit. 3. The photosensitive drum cleaning mechanism according to claim 2, wherein: When the sheet 5. A tractor unit is set, the paper size detection unit of the tractor unit outputs the sheet width data (W) of the paper read to the print density determination unit of the control unit, the print start Then, in the print density determination unit, the paper width data (W) is input to the paper size input unit, and the standard print density in the paper width data (W) is calculated by the toner supply amount calculation unit at the reference print density for each paper width. A reference setting value (P0) of the number of pages of the drive interval of the toner supply motor which is the toner supply amount at the time is calculated, and the reference setting value (P0) is 3% which is a standard for 15-inch wide paper. If the printing density is as follows, the toner consumption per page is 60 mg. If the toner is replenished every time 3000 mg is consumed, the toner supply motor is driven once every 50 pages. Therefore, P0 = 50 × (15 / W ) And at the same time When the toner supply motor monitoring unit that monitors the driving of the toner supply motor obtains the number of printed pages (P1) at the drive interval of the toner supply motor that is actually operating from the printed sheet count unit, The print density (D) is calculated by a print density calculation unit for comparison with the reference set value (P0) at the standard print density of 3% calculated by the toner supply amount calculation unit at the reference print density. Is D = 3 × P0
The print density (D) calculated by / P1 and calculated by the print density calculation unit is output from the print density output unit to the cleaning mechanism drive unit. In the cleaning mechanism drive unit, the print density (D) is calculated by the print density determination unit. The print density (D) is input to the print density input unit, and the cleaning operation unit drives the brush motor that drives the cleaning brush that cleans the photosensitive drum based on the input print density (D). The operation amount (O) of the valve motor that drives the valve that controls the suction force of the blower is calculated based on the rotation speed (T) and the opening ratio, and the brush motor drive speed (T) calculated by the cleaning operation unit is calculated. The brush motor operation command section drives the brush motor, and the valve operation command section is based on the valve motor operation amount (O) calculated by the cleaning operation section. When the print density (D) of the print data calculated by the print density density determination unit is high, the motor for the brush is driven so as to increase the rotation speed of the cleaning brush, and at the same time, the valve is closed to clean the cleaning brush. In order to increase the suction force of the unit, the valve motor is driven.
The driving rotation speed (T) of the brush motor is calculated from the printing density (D) as T = A × D / 3 (A is the rotation speed at a printing density of 3%), and the operation amount of the valve motor ( O)
From the movement amount O2 from the initial position and the position O1 before the change, O
2 = B × D (B is a constant coefficient of valve motor operation amount) O =
A photosensitive drum cleaning method characterized by being calculated by O2-O1. 6. A paper feeding unit for feeding a sheet, a tractor unit for feeding the sheet, a printing unit for forming characters and images, and a fixing unit for fixing the toner placed on the sheet at the printing unit. And a stacker for storing the discharged paper, wherein the printing unit includes the photosensitive drum cleaning mechanism according to claim 1 for cleaning the photosensitive drum using an electrophotographic method. Printing device.