JP2018031948A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that reduces a trouble that a lubricant is excessively supplied to a surface of an image carrier.SOLUTION: An image forming apparatus comprises: a second drive motor 45 (varying means) that varies the amount of lubricant per unit time supplied to a surface of a photoreceptor drum 11 (image carrier) by a lubricant supply device 15; detection means 40, 47, and 60 that detect the ratio of the cumulative travel distance for a printing area to the cumulative travel distance on the photoreceptor drum 11; and a control part 60 (control means) that controls the second drive motor 45 so that the amount of lubricant per unit time is varied according to the ratio detected by the detection means 40, 47, and 60.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming apparatus using an electrophotographic system, such as a copying machine, a printer, a facsimile machine, or a complex machine thereof.

  Conventionally, in an image forming apparatus such as a copying machine or a printer, the surface of an image carrier is lubricated for the purpose of reducing deterioration with time and occurrence of abnormal images due to wear of the image carrier such as a photosensitive drum or a cleaning blade. A technique for installing a lubricant supply device (lubricant coating device) for supplying a lubricant is known (see, for example, Patent Document 1).

On the other hand, Patent Document 1 discloses the rotation of a lubricant supply roller that is in sliding contact with an image carrier for the purpose of always supplying a stable amount of lubricant to the surface of the image carrier such as a photosensitive drum or an intermediate transfer belt. A technique for changing the number based on a predetermined condition is disclosed.
Specifically, in Patent Document 1, the lubricant supply device includes a lubricant supply roller that is in sliding contact with the photosensitive drum (image carrier), a solid lubricant that is in contact with the lubricant supply roller, and a solid lubricant that is supplied to the lubricant supply roller. It is composed of an urging member that urges toward the surface. Then, the lubricant is gradually scraped off from the solid lubricant by the lubricant supply roller rotating in a predetermined direction, and the lubricant scraped off and transported by the lubricant supply roller is applied (supplied) to the surface of the photosensitive drum. The
In Patent Document 1, the amount of lubricant supplied onto the photosensitive drum is changed by varying the number of revolutions of the lubricant supply roller based on predetermined conditions such as the total travel distance and environment of the lubricant supply roller. We are trying not to make any excess or deficiency.

The lubricant supply device disclosed in Patent Document 1 described above changes the rotational speed of the lubricant supply roller to an optimum value based on predetermined conditions such as the total travel distance and environment of the lubricant supply roller. It can be expected that the amount of lubricant supplied to the surface of the carrier is less likely to be excessive or insufficient.
However, the conventional lubricant supply device, including the one disclosed in Patent Document 1, depends on the ratio of the cumulative travel distance of the print area to the cumulative travel distance of the image carrier, and the surface of the image carrier. In some cases, the lubricant was excessively supplied.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide an image forming apparatus in which the problem of excessive supply of lubricant to the surface of an image carrier is reduced.

  The image forming apparatus according to the present invention includes an image carrier that carries a toner image and travels in a predetermined direction, a lubricant supply device that supplies a lubricant to a surface of the image carrier, and the lubricant supply device A variable means for varying the amount of lubricant per unit time supplied to the surface of the image carrier, and a ratio of the cumulative travel distance for the print area to the cumulative travel distance on the image carrier is detected directly or indirectly. And a control unit that controls the variable unit such that the amount of lubricant per unit time is varied according to the ratio detected by the detection unit.

  According to the present invention, it is possible to provide an image forming apparatus in which a problem that excessive lubricant is supplied to the surface of the image carrier is reduced.

1 is an overall configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. It is a block diagram which shows a process cartridge and its vicinity. It is a timing chart which shows the control which varies lubricant supply amount. It is a timing chart which shows the control which varies the lubricant supply amount as a modification.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

First, the overall configuration and operation of the image forming apparatus 1 will be described with reference to FIGS. 1 and 2.
FIG. 1 is an overall configuration diagram showing an image forming apparatus 1 according to an embodiment. FIG. 2 is a cross-sectional view showing a configuration of a yellow process cartridge 10Y (image forming unit) installed in the image forming apparatus 1 of FIG.
Since the four process cartridges 10Y, 10M, 10C, and 10BK (image forming units) have substantially the same structure except that the color of the toner T used in the image forming process is different, the process cartridge 10Y for yellow is shown in FIG. Only a representative is shown.

  In FIG. 1, 1 is a tandem color copier as an image forming apparatus, 2 is a writing unit that emits laser light based on input image information, 3 is a document conveying unit that conveys a document D to a document reading unit 4, and 4 is An original reading unit that reads image information of the original D, 7 is a paper feeding unit that accommodates a recording medium such as paper, 9 is a registration roller that adjusts the conveyance timing of the recording medium, 10Y, 10M, 10C, and 10BK are each color (yellow) , Magenta, cyan, and black) are formed on the intermediate transfer belt 17 by superimposing the toner images formed on the photosensitive drums of the process cartridges 10Y, 10M, 10C, and 10BK on the intermediate transfer belt 17. Primary transfer bias roller 17, an intermediate transfer belt 17 on which toner images of a plurality of colors are superimposed and transferred, and 18 a toner on the intermediate transfer belt 17 A secondary transfer bias roller for transferring the toner image onto the recording medium, 19 an intermediate transfer belt cleaning unit for cleaning the intermediate transfer belt 17, and 20 a fixing device for fixing the toner image (unfixed image) on the recording medium. Show.

Hereinafter, an operation during normal color image formation in the image forming apparatus will be described.
First, the document D is transported from the document table in the direction of the arrow in the drawing by the transport rollers of the document transport unit 3 and placed on the contact glass 5 of the document reading unit 4. Then, the document reading unit 4 optically reads the image information of the document D placed on the contact glass 5.

  Specifically, the document reading unit 4 scans the image of the document D on the contact glass 5 while irradiating light emitted from an illumination lamp. Then, the light reflected by the document D is imaged on the color sensor via the mirror group and the lens. The color image information of the document D is read for each RGB (red, green, blue) color separation light by the color sensor, and then converted into an electrical image signal. Further, color conversion processing, color correction processing, spatial frequency correction processing, and the like are performed by the image processing unit based on the RGB color separation image signals to obtain yellow, magenta, cyan, and black color image information.

  Then, the image information of each color of yellow, magenta, cyan, and black is transmitted to the writing unit 2. Then, the laser beam L (exposure light) based on the image information of each color is directed from the writing unit 2 onto the photosensitive drum 11 (image carrier) of the corresponding process cartridge 10Y, 10M, 10C, 10BK, respectively. It is emitted.

On the other hand, the photosensitive drums 11 (refer to FIG. 2) of the four process cartridges 10Y, 10M, 10C, and 10BK rotate (run) in a predetermined direction (counterclockwise), respectively. First, the surface of the photosensitive drum 11 is uniformly charged at a portion facing the charging device 12 (a charging step). In this way, a charging potential (about −900 V) is formed on the photosensitive drum 11. Thereafter, the surface of the charged photosensitive drum 11 reaches the irradiation position of each laser beam L.
In the writing unit 2, laser light L corresponding to the image signal is emitted from the four light sources corresponding to each color. Each laser beam L passes through a different optical path for each of the yellow, magenta, cyan, and black color components (this is an exposure process).

  The laser beam L corresponding to the yellow component is applied to the surface of the first photosensitive drum 11 (image carrier) from the left side of the drawing. At this time, the yellow component laser light is scanned in the rotation axis direction (main scanning direction) of the photosensitive drum 11 by a polygon mirror that rotates at high speed. Thus, an electrostatic latent image (an exposure potential of about −50 to 100 V is formed) corresponding to the yellow component is formed on the photosensitive drum 11 charged by the charging device 12.

  Similarly, the laser beam corresponding to the magenta component is irradiated on the surface of the second photosensitive drum 11 from the left side of the paper, and an electrostatic latent image corresponding to the magenta component is formed. The cyan component laser light is applied to the surface of the third photosensitive drum 11 from the left side of the drawing to form an electrostatic latent image of the cyan component. The black component laser light is applied to the surface of the fourth photosensitive drum 11 from the left side of the drawing, and an electrostatic latent image of the black component is formed.

Thereafter, the surface of the photosensitive drum 11 on which the electrostatic latent image of each color is formed reaches a position facing the developing device 13. Then, each color toner is supplied from each developing device 13 onto the photosensitive drum 11, and the latent image on the photosensitive drum 11 is developed to form a toner image (this is a developing step).
Thereafter, the surface of the photosensitive drum 11 after the development process reaches a portion facing the intermediate transfer belt 17 (primary transfer nip). Here, a primary transfer bias roller 16 is installed at each facing portion so as to be in contact with the inner peripheral surface of the intermediate transfer belt 17. Then, at the position of the primary transfer bias roller 16, the toner images of the respective colors formed on the photosensitive drum 11 are sequentially transferred onto the intermediate transfer belt 17 (primary transfer process).

Then, the surface of the photosensitive drum 11 after the primary transfer process reaches a position facing the cleaning device 14 (cleaning unit). At this position, the untransferred toner remaining on the photosensitive drum 11 is mechanically removed by the cleaning blade 14a and the cleaning brush roller 14b, and the removed untransferred toner is collected in the cleaning device 14. (This is a cleaning process.) The untransferred toner collected in the cleaning device 14 is transported to the outside of the cleaning device 14 by a transport screw, and is collected as waste toner in the waste toner collection container.
Thereafter, the surface of the photosensitive drum 11 sequentially passes through the position of the lubricant supply device 15 and the charge eliminating unit, and a series of image forming processes on the photosensitive drum 11 is completed.

On the other hand, the intermediate transfer belt 17 on which the toners of the respective colors on the photosensitive drum 11 are transferred (carrying) are run in the clockwise direction in the drawing and are opposed to the secondary transfer bias roller 18 (secondary transfer). Nip). Then, a color toner image carried on the intermediate transfer belt 17 is transferred onto a recording medium (paper) at a position facing the secondary transfer bias roller 18 (secondary transfer process).
Thereafter, the surface of the intermediate transfer belt 17 reaches the position of the intermediate transfer belt cleaning unit 19. Then, the untransferred toner adhered on the intermediate transfer belt 17 is collected by the intermediate transfer belt cleaning unit 19, and a series of transfer processes in the intermediate transfer belt 17 is completed.

Here, the recording medium transported between the intermediate transfer belt 17 and the secondary transfer bias roller 18 (secondary transfer nip) is transported from the paper feed unit 7 via the registration roller 9 and the like. Is.
Specifically, the recording medium fed by the paper feeding roller 8 from the paper feeding unit 7 that stores the recording medium is guided to the registration roller 9 (timing roller) after passing through the conveyance guide. The recording medium that has reached the registration roller 9 is conveyed toward the secondary transfer nip at the same timing.

Then, the recording medium on which the full-color image is transferred is guided to the fixing device 20 by the conveyance belt. In the fixing device 20, the color image (toner) is fixed on the recording medium at the nip between the fixing belt and the pressure roller.
Then, the recording medium after the fixing process is discharged as an output image outside the apparatus main body 1 by a paper discharge roller, and a series of image forming processes (image forming operations) is completed.

Next, the process cartridge 10Y will be described in detail with reference to FIG.
As shown in FIG. 2, the process cartridge 10Y includes a photosensitive drum 11 as an image carrier, a charging device 12 (charging unit), a developing device 13 (developing unit), a cleaning device 14 (cleaning unit), The lubricant supply device 15 is integrally configured as a unit. The process cartridge 10Y is detachably (replaceable) with respect to the image forming apparatus main body 1, and is appropriately removed from the image forming apparatus main body 1 to be replaced with a new one or repaired. Become.

Here, the photosensitive drum 11 as an image bearing member is a negatively charged organic photosensitive member, and a photosensitive layer or the like is provided on a drum-shaped conductive support.
In the photosensitive drum 11, an undercoat layer as an insulating layer, a charge generation layer and a charge transport layer as a photosensitive layer, and a surface layer (protective layer) are sequentially laminated on a conductive support as a base layer.
The photosensitive drum 11 is driven to rotate counterclockwise in FIG. 2 by a first drive motor 50 (main motor).

Referring to FIG. 2, charging device 12 is a charging roller in which an outer periphery of a conductive metal core is covered with a medium-resistance elastic layer, and is opposed to photoconductor drum 11 with a small gap. It is installed as follows. A predetermined voltage (charging bias) is applied to the charging device 12 from the charging power supply unit, thereby uniformly charging the surface of the opposing photosensitive drum 11.
In this embodiment, as the charging device 12, a contact-type charging roller that abuts on the photosensitive drum 11 can be used, or a charging charger having a grid using a corona discharge method can be used.
Further, as the charging bias applied to the charging device 12, an AC voltage may be superimposed on a DC voltage, or only a DC voltage may be used.

The developing device 13 mainly includes a developing roller 13a facing the photosensitive drum 11, a first conveying screw 13b facing the developing roller 13a, and a second conveying screw 13c facing the first conveying screw 13b via a partition member. And a doctor blade 13d facing the developing roller 13a. The developing roller 13a includes a magnet that is fixed inside and forms a magnetic pole on the peripheral surface of the roller, and a sleeve that rotates around the magnet. A plurality of magnetic poles are formed on the developing roller 13a (sleeve) by the magnet, and the developer G is carried on the developing roller 13a. In the developing device 13, a two-component developer G composed of carrier C and toner T is accommodated.
The developing roller 13a and the two conveying screws 13b and 13c are rotationally driven by a developing driving motor provided separately from the first driving motor 50 that rotationally drives the photosensitive drum 11.

The cleaning device 14 includes a cleaning blade 14 a that contacts the surface of the photosensitive drum 11 to clean the surface of the photosensitive drum 11, and rotates in a predetermined direction while contacting the surface of the photosensitive drum 11. And a cleaning brush roller 14b that cleans the surface.
The cleaning blade 14a is made of a rubber material such as urethane rubber, and is in contact with the surface of the photosensitive drum 11 at a predetermined angle and a predetermined pressure. As a result, untransferred toner adhering to the photosensitive drum 11 (paper powder generated from the recording medium, discharge products generated on the photosensitive drum 11 when discharged by the charging device 12, additive added to the toner, etc.) It is assumed that the deposits are also included.) Is mechanically scraped off and collected in the cleaning device 14. In the present embodiment, the cleaning blade 14 a is in contact with the photosensitive drum 11 in the counter direction with respect to the traveling direction (rotating direction) of the photosensitive drum 11.
The cleaning brush roller 14b is a brush in which straight or loop-shaped bristles made of resin fibers such as polyester, nylon, rayon, acrylic, vinylon, and vinyl chloride are wound around the outer periphery of a cored bar. The hair comes into sliding contact with the surface of the photosensitive drum 11. The cleaning brush roller 14b is driven to rotate counterclockwise in FIG. 2 by receiving a driving force from the first driving motor 50 that rotates the photosensitive drum 11 through a gear train. As a result, untransferred toner adhering to the photosensitive drum 11 (paper powder generated from the recording medium, discharge products generated on the photosensitive drum 11 when discharged by the charging device 12, additive added to the toner, etc.) It is assumed that the deposits are also included.) Is mechanically scraped off and collected in the cleaning device 14.

Referring to FIG. 2, the lubricant supply device 15 includes a lubricant supply roller 15 a (lubricant supply member) that is provided with a foamed elastic layer that is in sliding contact with the photosensitive drum 11 and supplies the lubricant onto the photosensitive drum 11. ), A solid lubricant 15b in sliding contact with the lubricant supply roller 15a (foaming elastic layer), a compression spring 15c as an urging member for urging the solid lubricant 15b against the lubricant supply roller 15a, and the photosensitive drum 11 A thinning blade 15f (leveling blade) for thinning (homogenizing) the lubricant that comes into contact with and supplied onto the photosensitive drum 11 is formed.
The lubricant supply device 15 is disposed on the downstream side in the rotational direction of the photosensitive drum 11 with respect to the cleaning device 14 (cleaning blade 14a), and on the upstream side in the rotational direction of the photosensitive drum 11 with respect to the charging device 12. ing. The thinning blade 15f is disposed on the downstream side in the rotation direction of the photosensitive drum 11 with respect to the lubricant supply roller 15a.

  The lubricant supply roller 15a is a roller-like member in which a foamed elastic layer made of foamed polyurethane (urethane foam) is formed on a shaft part (core metal) made of a metal material, and the foamed elastic layer is the photosensitive drum 11. The second drive motor 45 is driven to rotate counterclockwise in FIG. 2 while being in contact with the surface. As a result, the lubricant is supplied from the solid lubricant 15b to the photosensitive drum 11 via the lubricant supply roller 15a.

Here, the second drive motor 45 that rotationally drives the lubricant supply roller 15a drives the first drive motor 50 (main motor) that rotationally drives the photosensitive drum 11, the cleaning brush roller 14b, and the like, and the developing device 13. It is a motor that is provided separately from the development drive motor and that drives only the lubricant supply roller 15a.
The second drive motor 45 is a variable rotation speed motor, and is configured to be able to vary the rotation speed of the lubricant supply roller 15a under the control of the control unit 60.
Then, using the second drive motor 45 configured as described above, a “control mode (lubricant supply reduction mode)” is executed in which the lubricant supply roller 15a is rotated at a low speed when a predetermined condition is satisfied. The amount of lubricant supplied onto the drum 11 is varied (decreased), which will be described in detail later.

The lubricant supply roller 15a is rotationally driven so as to be in sliding contact with the photosensitive drum 11 rotating in the counterclockwise direction in FIG. 2 in the counter direction (reverse direction) (counterclockwise rotation in FIG. 2). ). That is, the rotation direction of the lubricant supply roller 15 a is configured to be opposite to the rotation direction (traveling direction) of the photosensitive drum 11 at the sliding contact position with the photosensitive drum 11.
The lubricant supply roller 15a is disposed so as to be in sliding contact with the solid lubricant 15b and the photosensitive drum 11, and the lubricant supply roller 15a rotates to scrape the lubricant from the solid lubricant 15b. The lubricant is applied on the photosensitive drum 11.
A compression spring 15c (biasing member) is disposed behind the solid lubricant 15b (lubricant holding member 15e) in order to eliminate uneven contact between the lubricant supply roller 15a and the solid lubricant 15b. The solid lubricant 15b is urged toward the lubricant supply roller 15a.

Here, the solid lubricant 15b is formed by adding an inorganic lubricant to fatty acid metal zinc. Moreover, as fatty acid metal zinc, what contains at least zinc stearate is preferable. The inorganic lubricant is preferably at least one of talc, mica, and boron nitride.
Zinc stearate is a typical lamellar crystal powder. A lamellar crystal has a layered structure in which amphiphilic molecules are self-organized, and when a shearing force is applied, the crystal breaks along the layers and is slippery. Therefore, the surface of the photosensitive drum 11 can be made to have low friction. In other words, the surface of the photosensitive drum 11 can be effectively covered with a small amount of lubricant by the lamellar crystals that receive the shearing force and uniformly cover the surface of the photosensitive drum 11. Then, the surface of the photosensitive drum 11 can be covered relatively evenly and well protected from electrical stress in the charging process.
Further, by using an inorganic lubricant having a plate-like structure such as talc, mica, and boron nitride, it is difficult for toner and lubricant to slip through the cleaning device 14 (cleaning blade 14a), and the charging device 12 is It can be made difficult to get dirty.

  The thinning blade 15f is a plate-like member made of a rubber material such as urethane rubber, and is in contact with the surface of the photosensitive drum 11 at a predetermined angle and a predetermined pressure. The thinning blade 15f is disposed on the downstream side in the rotation direction of the photosensitive drum 11 (downstream in the traveling direction) with respect to the cleaning blade 14a. The lubricant supplied onto the photoreceptor drum 11 by the lubricant supply roller 15a is thinned uniformly and in an appropriate amount on the photoreceptor drum 11 by the thinning blade 15f.

When the solid lubricant 15b is applied to the surface of the photosensitive drum 11 via the lubricant supply roller 15a, a powdery lubricant is applied to the surface of the photosensitive drum 11, but in this state, the lubricity is low. Since it is not sufficiently exhibited, the thinning blade 15f functions as a member for thinning and uniformizing the lubricant. The thinning blade 15f forms a film of the lubricant on the photosensitive drum 11, and the lubricant exhibits its lubricity sufficiently.
In the present embodiment, the thinning blade 15f is in contact with the photosensitive drum 11 in the counter direction with respect to the traveling direction (rotating direction) of the photosensitive drum 11, but the traveling of the photosensitive drum 11 is performed. You may comprise so that it may contact | abut to the photosensitive drum 11 in a trading direction with respect to a direction (rotation direction).

  As described above, in this embodiment, since the two blade members of the cleaning blade 14a and the thinning blade 15f are provided separately, the cleaning property and the lubricant application property can be maintained well. In addition, wear and deterioration of both blade members 14a and 15f can be reduced by supplying the lubricant to the photosensitive drum 11.

The image forming process described above will be described in more detail with reference to FIG.
The developing roller 13a rotates in the direction of the arrow in FIG. The developer G in the developing device 13 is moved from the toner replenishing portion 30 to the toner replenishing port by the rotation of the first conveying screw 13b and the second conveying screw 13c arranged with a partition member therebetween. The toner T circulates in the longitudinal direction (in the direction perpendicular to the paper surface of FIG. 2) while being agitated and mixed with the toner T supplied through the toner.

  The toner T that is frictionally charged and adsorbed on the carrier C is carried on the developing roller 13a together with the carrier C. The developer G carried on the developing roller 13a then reaches the position of the doctor blade 13d. The developer G on the developing roller 13a is adjusted to an appropriate amount at the position of the doctor blade 13d, and then reaches a position facing the photosensitive drum 11 (development area).

  Thereafter, in the developing region, the toner T in the developer G adheres to the electrostatic latent image formed on the surface of the photosensitive drum 11. Specifically, it is formed by the potential difference (developing potential) between the latent image potential (exposure potential) of the image area irradiated with the laser beam L and the developing bias (about −500 V) applied to the developing roller 13a. The toner T adheres to the latent image by the electric field.

  Thereafter, most of the toner T adhering to the photosensitive drum 11 in the developing process is transferred onto the intermediate transfer belt 17. The untransferred toner T adhering (remaining) to the surface of the photosensitive drum 11 is collected in the cleaning device 14 by the cleaning blade 14a and the cleaning brush roller 14b. Thereafter, the surface of the photosensitive drum 11 after the cleaning process sequentially passes through the lubricant supply device 15 and the charge eliminating unit, and a series of image forming processes is completed.

  Here, the toner replenishing unit 30 provided in the image forming apparatus main body 1 includes a toner bottle 31 configured to be replaceable, and a toner hopper that holds and rotates the toner bottle 31 and replenishes the developing device 13 with new toner T. Part 32. Also, a new toner T (in FIG. 2, yellow toner) is accommodated in the toner bottle 31. In addition, a spiral protrusion is formed on the inner peripheral surface of the toner bottle 31.

  The new toner T in the toner bottle 31 is appropriately replenished into the developing device 13 from the toner replenishing port as the toner T in the developing device 13 (existing toner) is consumed. Consumption of the toner T in the developing device 13 is detected indirectly or directly by a magnetic sensor installed below the second conveying screw 13c of the developing device 13.

Hereinafter, the characteristic configuration and operation of the image forming apparatus 1 according to the present embodiment will be described.
In the image forming apparatus 1 (lubricant supply device 15) in the present embodiment, the amount of lubricant per unit time supplied to the photosensitive drum 11 (the surface of the image carrier) by the lubricant supply device 15 is varied. A second drive motor 45 is provided as variable means.
The second drive motor 45 as the variable means is a motor with a variable rotation speed, and is configured to be able to change the rotation speed of the lubricant supply roller 15a under the control of the control unit 60. When the lubricant supply roller 15a is rotated at a low speed by the second drive motor 45 controlled by the control unit 60, the photosensitive drum 11 is compared with when the lubricant supply roller 15a is driven at a high speed. This reduces the amount of lubricant supplied to the surface (the amount of lubricant per unit time).

In the present embodiment, the control unit 60 controls the second drive motor 45 so that the rotational speed of the lubricant supply roller 15a can be varied in two stages.
Specifically, in the present embodiment, during normal operation (hereinafter referred to as “lubricant supply standard mode” where appropriate), the rotational speed of the lubricant supply roller 15a is set to 200 rpm. On the other hand, as will be described later, when a predetermined condition is satisfied, the rotational speed of the lubricant supply roller 15a is set to 100 rpm, and the amount of lubricant supplied onto the photosensitive drum 11 is reduced (hereinafter referred to as “reduced amount”). This control mode is appropriately referred to as “lubricant supply reduction mode”.

In addition, the image forming apparatus 1 according to the present embodiment is provided with a detecting unit that detects a ratio of the accumulated traveling distance corresponding to the print area to the accumulated traveling distance of the photosensitive drum 11 (image carrier).
Here, the “cumulative travel distance on the photoconductor drum 11” is an operation distance in the sub-scanning direction (rotation direction) in which the photoconductor drum 11 has operated, and is equal to the circumferential length (diameter × π) of the photoconductor drum 11. It is a value multiplied by the total number of rotations.
The “cumulative travel distance for the print area” is the operation distance in the sub-scanning direction of the print area (image area) of the photosensitive drum 11 corresponding to the size of the recording medium (paper) in the sub-scanning direction (conveyance direction). Thus, it generally matches the sum of the sizes in the transport direction of all the recording media involved in the image forming operation (all the sheets on which the toner image on the photosensitive drum 11 has been transferred).

That is, the cumulative travel distance X on the photosensitive drum 11 is the sum of the cumulative travel distance X1 for the print area (image area) and the cumulative travel distance X2 for the non-print area (non-image area) ( X = X1 + X2). The “non-print region” is a region in the rotational direction that is not a print region on the surface of the photosensitive drum 11 that rotates in a predetermined direction (hereinafter, referred to as “idle rotation region” as appropriate) before and after the printing operation. Not only the area before and after the corresponding print area, the area corresponding to the space between continuous paper passes, but also all areas for warm-up operations and process adjustment operations (process control) that do not involve paper passing (transfer process) Will be included.
In this embodiment, the detection means detects whether the cumulative travel distance for the print area (or the non-print area) is greater or smaller than the cumulative travel distance on the photosensitive drum 11. Become. When the ratio of the cumulative travel distance for the print area to the cumulative travel distance on the photosensitive drum 11 is large, the cumulative travel distance for the print area is large, and the cumulative travel distance for the non-print area (for the idling region) is large. There will be less. On the other hand, when the ratio of the cumulative travel distance for the print area to the cumulative travel distance on the photosensitive drum 11 is small, the cumulative travel distance for the print area is small and the non-print area (idle rotation area). The cumulative mileage will be large.

Specifically, in the present embodiment, the detecting means detects the ratio of the cumulative number of printed sheets converted to a predetermined size with respect to the total number of jobs in which a series of image forming operations has been performed. The ratio of the cumulative travel distance for the print area to the cumulative travel distance is indirectly detected.
Here, “job” refers to the photosensitive drum 11 after the printing operation is completed regardless of whether the printing is a single print or a plurality of continuous prints after the rotation of the photosensitive drum 11 is started. This is the operation until the rotation stops. Therefore, for example, when one print is performed three times and continuous print is performed twice, the “total number of jobs” is detected as five.
The “cumulative number of prints converted to a predetermined size” is the total sum of the sizes in the transport direction of all the recording media (paper) involved in the image forming operation converted to the predetermined size. When 10 sheets and 3 sheets of A3 vertical size are passed, the cumulative number of printed sheets converted to a predetermined size (A4 horizontal size) is detected as 16 sheets.

That is, when the ratio of the cumulative number of prints to the total number of jobs is small, the idling region of the photosensitive drum 11 becomes large. Therefore, the cumulative travel distance of the print region with respect to the cumulative travel distance of the photosensitive drum 11 is increased. A state where the ratio is small is indirectly detected. On the other hand, when the ratio of the cumulative number of printed sheets to the total number of jobs is large, the idle rotation area of the photosensitive drum 11 becomes small. A state in which the ratio of the travel distance is increased is indirectly detected.
Note that an operation panel 40 is installed on the exterior of the image forming apparatus main body 1, and information related to a printing operation (number of prints per job) input by the user to the operation panel 40 is sent to the control unit 60. Thus, the number of jobs and the number of prints are stored in the storage unit of the control unit 60, and the total number of jobs and the number of accumulated prints are counted up in the counter 47. Accordingly, the operation panel 40, the counter 47, and the control unit 60 function as a detection unit that detects the ratio of the cumulative number of prints to the total number of jobs.

In the present embodiment, the detection means for detecting the ratio of the cumulative number of prints to the total number of jobs causes the photosensitive drum 11 (image carrier) to rotate idle (running idle) without performing a series of image forming operations. In this case, it is added to the total number of jobs as a series of image forming operations.
That is, as described above, the photosensitive drum 11 rotates idly even when a warming-up operation or a process adjustment operation that does not involve paper passing (transfer process) is performed (the idling region is Therefore, the number of jobs is added without adding the number of prints when these operations are performed. For example, when the warm-up operation is performed once, the total number of jobs is incremented by one while keeping the accumulated number of prints.
Thus, even when the ratio of the cumulative number of printed sheets to the total number of jobs is detected, the ratio of the cumulative travel distance for the print area to the cumulative travel distance on the photosensitive drum 11 can be indirectly detected with high accuracy. .

In the image forming apparatus 1 according to the present embodiment, the control unit 60 as the control unit detects the ratio detected by the detection unit (the ratio of the cumulative travel distance for the print area to the cumulative travel distance on the photosensitive drum 11). Accordingly, the second drive motor 45 (variable means) is controlled so that the amount of lubricant per unit time can be varied.
Specifically, in the present embodiment, the rotation number of the lubricant supply roller 15a is varied by the control unit 60 in accordance with the “ratio of the cumulative number of printed sheets to the total number of jobs” detected by the detecting unit. The second drive motor 45 (variable means) is controlled.

Such control is performed in a state where excessive lubricant is supplied to the surface of the photosensitive drum 11 depending on the ratio of the cumulative traveling distance of the print area to the cumulative traveling distance of the photosensitive drum 11. This is because there are cases where the
Specifically, when the ratio of the cumulative travel distance corresponding to the print area to the cumulative travel distance of the photoconductor drum 11 decreases (when the ratio of the idling region of the photoconductor drum 11 increases), the surface of the photoconductor drum 11 is excessively lubricated. It becomes easy to become the state where the agent was supplied. This is because a part of the lubricant supplied (applied) to the print area on the photosensitive drum 11 is transferred onto the intermediate transfer belt 17 together with the toner image in the print area in the primary transfer process. On the other hand, the lubricant supplied (applied) to the non-printing region remains on the photosensitive drum 11 as it is. For this reason, the higher the ratio of the idling region of the photosensitive drum 11 is, the more the lubricant is more likely to be supplied to the surface of the photosensitive drum 11.
If the lubricant is excessively supplied to the surface of the photosensitive drum 11 as described above, uneven application of the lubricant on the photosensitive drum 11 even if the thinning blade 15f is installed. As a result, streaky abnormal images are likely to occur in the image formed on the photosensitive drum 11.
On the other hand, in the present embodiment, the amount of lubricant supplied onto the photosensitive drum 11 is adjusted according to the ratio of the cumulative traveling distance of the print area to the cumulative traveling distance of the photosensitive drum 11. Therefore, it is possible to reduce the occurrence of such a problem.

Specifically, when the ratio detected by the detection means (the ratio of the cumulative travel distance for the print area to the cumulative travel distance of the photosensitive drum 11) is small, the control unit 60 (control means) has the ratio. The second drive motor 45 (variable means) is controlled so that the amount of lubricant per unit time is smaller than when it is large.
Specifically, in the present embodiment, when the “ratio of the cumulative number of prints to the total number of jobs” detected by the detection unit by the control unit 60 is small, the lubricant supply roller is larger than when the ratio is large. The second drive motor 45 (variable means) is controlled so that the rotational speed of 15a is decelerated.

More specifically, the control unit 60 (control unit) has a ratio (the ratio of the cumulative travel distance for the print area to the cumulative travel distance of the photosensitive drum 11) detected by the detection unit smaller than a predetermined value M. Sometimes, the second drive motor 45 (variable means) is controlled so that the amount of lubricant per unit time is reduced.
Specifically, in the present embodiment, when the “ratio of the cumulative number of printed sheets to the total number of jobs” detected by the detection unit by the control unit 60 is smaller than a predetermined value A, the rotational speed of the lubricant supply roller 15a. The second drive motor 45 (variable means) is controlled so that is decelerated (so as to shift from the lubricant supply standard mode to the lubricant supply reduction mode).

  By performing such control, the lubricant is excessively supplied to the surface of the photosensitive drum 11 as described above, and the image formed on the photosensitive drum 11 is streaked. The problem that the abnormal image is generated is surely reduced.

Hereinafter, the above-described control for changing the lubricant supply amount will be described in summary with reference to the flowchart of FIG.
As shown in FIG. 3, first, when a job is started by a user operation on the operation panel 40 (step S1), the “total number of jobs” stored in the storage unit of the control unit 60 is called (step S2). Further, the “cumulative print number” of the counter 47 is read (step S3). Then, the “cumulative print number / total number of jobs” is calculated by the calculation unit of the control unit 60, and it is determined whether or not the value is smaller than the predetermined value A (step S4).
As a result, if it is determined that “cumulative print number / total number of jobs” is not smaller than the predetermined value A, it is assumed that the lubricant is not excessively supplied to the surface of the photosensitive drum 11. The lubricant supply standard mode is executed (step S6). That is, the rotation speed of the lubricant supply roller 15a is set to a normal value (in this embodiment, 200 rpm). Then, a desired printing operation is performed in a state where the lubricant supply roller 15a is rotationally driven at a normal rotational speed (step S7), and this job is ended (step S8).
On the other hand, if it is determined in step S4 that “cumulative print number / total job number” is smaller than the predetermined value A, the lubricant is excessively supplied to the surface of the photosensitive drum 11. As a state, the lubricant supply reduction mode is executed (step S5). That is, the rotation speed of the lubricant supply roller 15a is set to a value smaller than the normal value (in this embodiment, 100 rpm). Then, a desired printing operation is performed in a state where the lubricant supply roller 15a is rotationally driven at a low speed (step S7), and this job is ended (step S8).

In the present embodiment, the second drive motor 45 that varies the number of revolutions of the lubricant supply roller 15a is used as a variable means that varies the amount of lubricant supplied to the surface of the photosensitive drum 11.
On the other hand, as a variable means for changing the amount of lubricant supplied to the surface of the photosensitive drum 11, a moving mechanism 48 for changing the pressure contact force of the solid lubricant 15b against the lubricant supply roller 15a can be used.
Specifically, as shown in FIG. 2, the wall portion of the holding member 15e holding the compression spring 15c (biasing member) and the solid lubricant 15b (the wall portion with which one end side of the compression spring 15c contacts) is. The movable plate 15d is configured to be movable in the direction of the black double arrow in FIG. The movable plate 15d is moved to an arbitrary position by a moving mechanism 48 (for example, a cam mechanism) controlled by the control unit 60.
Specifically, in normal time (in the lubricant supply standard mode), the movable plate 15d is fixed at a reference position (for example, the position in FIG. 2) by the control of the moving mechanism 48 by the control unit 60. Become. In contrast, in the lubricant supply reduction mode, the movable plate 15d is moved and fixed in a direction away from the solid lubricant 15b (lubricant supply roller 15a) with respect to the reference position by the control of the moving mechanism 48 by the control unit 60. As a result, the spring force of the compression spring 15c (pressure contact force of the solid lubricant 15b against the lubricant supply roller 15a) is weakened, and the amount of lubricant supplied onto the photosensitive drum 11 is reduced.
Even when the variable means is configured as described above, the effects of the present invention as described above are exhibited.

In the present embodiment, the control unit 60 (control unit) controls the variable unit to control the normal unit (in the lubricant supply standard mode) and the lubricant supply reduction mode according to the ratio detected by the detection unit. Thus, the amount of lubricant supplied to the surface of the photosensitive drum 11 can be varied in two steps.
On the other hand, the amount of lubricant supplied to the surface of the photosensitive drum 11 is varied in three or more stages according to the ratio detected by the detection unit by the control of the variable unit by the control unit 60 (control unit). It can also be configured as follows.

<Modification>
FIG. 4 is a timing chart showing control for varying the lubricant supply amount as a modified example.
In the modification, the detection unit does not detect “the ratio of the cumulative number of prints to the total number of jobs”, but the detection unit calculates “the ratio of the cumulative travel distance for the print area to the cumulative travel distance of the photosensitive drum 11”. It is detected directly (or almost directly).
Specifically, the “cumulative travel distance on the photoconductor drum 11 (image carrier)” is converted from the travel time (cumulative travel time) of the photoconductor drum 11 detected by the timer 46 shown in FIG. Can do. A value obtained by multiplying the running time (cumulative running time) of the photosensitive drum 11 by the linear velocity (process linear velocity) of the photosensitive drum 11 is the “cumulative running distance on the photosensitive drum 11”.
Further, the “cumulative travel distance for the print area” can be converted from the size in the transport direction of the recording medium (paper) involved in the image forming operation. The sum of the sizes in the transport direction of all the recording media onto which the toner image on the photosensitive drum 11 has been transferred is the “cumulative travel distance for the print area”.
Information relating to the size of the recording medium and the number of prints input to the operation panel 40 by the user is sent to the control unit 60 and the counter 47 for storage. Therefore, in addition to the timer 46, the operation panel 40, the counter 47, and the control unit 60 function as a detection unit that detects a “ratio of the cumulative travel distance for the print area to the cumulative travel distance of the photosensitive drum 11”. Become.

Hereinafter, control for varying the lubricant supply amount in the above-described modification will be described with reference to the flowchart of FIG.
As shown in FIG. 4, first, when a job is started by a user's operation on the operation panel 40 (step S1), the “cumulative travel distance” stored in the storage unit of the control unit 60 is read (step S12). Further, “cumulative travel distance (image scanning distance) for the print area” is read (step S13). Then, “cumulative travel distance (image scanning distance) / cumulative travel distance for the print area” is calculated by the calculation unit of the control unit 60, and it is determined whether the value is smaller than the predetermined value B (step S14). .
As a result, if it is determined that “image scanning distance / cumulative travel distance” is not smaller than the predetermined value B, it is assumed that the lubricant is not excessively supplied to the surface of the photosensitive drum 11. The lubricant supply standard mode is executed (step S6). Then, a desired printing operation is performed in the lubricant supply standard mode (step S7), and this job is ended (step S8).
On the other hand, if it is determined in step S14 that “image scanning distance / cumulative traveling distance” is smaller than the predetermined value B, the lubricant is excessively supplied to the surface of the photosensitive drum 11. As a state, the lubricant supply reduction mode is executed (step S5). Then, a desired printing operation is performed in the lubricant supply reduction mode (step S7), and this job is ended (step S8).
Even when such control is performed, the same effect as that of the present embodiment can be obtained.

As described above, the image forming apparatus 1 in the present embodiment varies the amount of lubricant per unit time supplied to the surface of the photosensitive drum 11 (image carrier) by the lubricant supply device 15. Detected by the drive motor 45 (variable means), detection means 40, 47, 60 for detecting the ratio of the cumulative travel distance for the print area to the cumulative travel distance on the photosensitive drum 11, and the detection means 40, 47, 60. A control unit 60 (control means) is provided for controlling the second drive motor 45 so that the amount of lubricant per unit time can be varied according to the ratio.
As a result, it is possible to reduce a problem that the lubricant is excessively supplied to the surface of the photosensitive drum 11.

In the present embodiment, the process drum 10Y is configured by integrating the photosensitive drum 11, the charging device 12 (charging unit), the developing device 13, the cleaning device 14, and the lubricant supply device 15, and the image forming unit. It is designed to be compact and improve maintenance workability.
On the other hand, these constituent members can be configured so as to be replaceable in the image forming apparatus main body 1 as a single unit without being a constituent member of the process cartridge. In particular, the lubricant supply device 15 can be configured to be replaceable in the image forming apparatus main body 1 as a single unit. Even in such a case, the same effect as that of the present embodiment can be obtained.
In the present application, “process cartridge” means a charging unit (charging device) for charging an image carrier, a developing unit (developing device) for developing a latent image formed on the image carrier, and an image carrier. It is defined as a unit in which at least one of a cleaning unit (cleaning device) for cleaning the top and an image carrier are integrated and installed detachably with respect to the image forming apparatus main body.

Further, in the present embodiment, the lubricant supply roller 15a having a foamed elastic layer formed on the core is used. However, the lubricant supply roller 15a has a straight or loop brush on the outer periphery of the core. What wound the hair can also be used. In that case, as the bristle, resin fibers such as polyester, nylon, rayon, acrylic, vinylon, and vinyl chloride can be used, and if necessary, conductive fibers mixed with a conductivity-imparting agent such as carbon can be used. it can. In addition, brush hair having a length (hair feet) of 0.2 to 20 mm and a brush density of 2 to 100,000 F / inch ² can be used.
In the present embodiment, the compression spring 15c is used as a biasing member that biases the solid lubricant 15b against the lubricant supply roller 15a, but the configuration of the biasing member is not limited to this. For example, a pair of rotating members disclosed in Patent Document 1 or the like can be used as the urging members.
Further, in the present embodiment, the cleaning blade 14a and the cleaning brush roller 14b are used as the cleaning members installed in the cleaning device 14, but only the cleaning blade 14a is used as the cleaning member without installing the cleaning brush roller 14b. You can also
In the present embodiment, the present invention is applied to the image forming apparatus 1 in which the lubricant supply device 15 that supplies the lubricant to the surface of the photosensitive drum 11 as the image carrier is installed. The present invention can also be applied to an image forming apparatus provided with a lubricant supply device for supplying a lubricant to the surface of the intermediate transfer belt 17 as a body.
Even in such a case, substantially the same effect as that of the present embodiment can be obtained.

  It should be noted that the present invention is not limited to the present embodiment, and it is obvious that the present embodiment can be modified as appropriate within the scope of the technical idea of the present invention, other than suggested in the present embodiment. is there. In addition, the number, position, shape, and the like of the constituent members are not limited to the present embodiment, and the number, position, shape, and the like suitable for implementing the present invention can be achieved.

1 image forming apparatus (image forming apparatus main body),
10Y, 10M, 10C, 10BK process cartridge,
11 Photosensitive drum (image carrier),
14 Cleaning device,
15 Lubricant supply device,
15a Lubricant supply roller (lubricant supply member),
15b solid lubricant,
15c compression spring (biasing member),
15d movable plate (variable means),
15e holding member,
40 Operation panel (detection means),
45 Second drive motor (variable means),
46 Timer (detection means),
47 Counter (detection means)
48 moving mechanism (variable means),
50 first drive motor,
60 Control unit (control means, detection means).

JP 2013-20232 A

Claims (7)

An image carrier that carries a toner image and travels in a predetermined direction;
A lubricant supply device for supplying a lubricant to the surface of the image carrier;
Variable means for varying the amount of lubricant per unit time supplied to the surface of the image carrier by the lubricant supply device;
Detecting means for directly or indirectly detecting a ratio of a cumulative travel distance for a print area to a cumulative travel distance in the image carrier;
Control means for controlling the variable means so that the amount of lubricant per unit time is variable according to the ratio detected by the detection means;
An image forming apparatus comprising:   The control means controls the variable means so that the amount of lubricant per unit time is smaller when the ratio detected by the detection means is small than when the ratio is large. The image forming apparatus according to claim 1.   The control means controls the variable means so that the amount of lubricant per unit time decreases when the ratio detected by the detection means is smaller than a predetermined value. Alternatively, the image forming apparatus according to claim 2.   4. The image according to claim 1, wherein the detection unit detects a ratio of a cumulative print number converted to a predetermined size with respect to a total number of jobs in which a series of image forming operations has been performed. Forming equipment.   The detecting means adds to the total number of jobs as a series of image forming operations performed even when the image carrier is idled without performing a series of image forming operations. Item 5. The image forming apparatus according to Item 4. The cumulative travel distance in the image carrier is converted from the travel time of the image carrier,
4. The image forming apparatus according to claim 1, wherein the cumulative travel distance for the print area is calculated from a size in a conveyance direction of a recording medium involved in an image forming operation. . The lubricant supply device includes:
A lubricant supply roller that rotates in a predetermined direction and is in sliding contact with the image carrier;
A solid lubricant in sliding contact with the lubricant supply roller;
A biasing member that biases the solid lubricant against the lubricant supply roller;
Comprising
The variable means varies the number of rotations of the lubricant supply roller or the pressure contact force of the solid lubricant against the lubricant supply roller. Image forming apparatus.

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