JP6149560B2 - Image forming apparatus - Google Patents

Description

  The present invention forms an image on a rotating image carrier, transfers the image formed on the image carrier to a transfer target, and removes the residue on the image carrier after the transfer with a cleaning member. The present invention relates to an image forming apparatus, and more particularly to improvement of a technique for applying a lubricant to an image carrier.

An image forming apparatus such as an electrophotographic printer charges a photosensitive drum as an example of a rotating image carrier and exposes the charged photosensitive drum to form an electrostatic latent image. The electrostatic latent image formed above is developed with a developer contained in a developing unit to form an image, and the formed image is transferred to a recording sheet.
Further, a residue such as toner remaining on the photosensitive drum without being transferred from the photosensitive drum to the recording sheet is removed by a cleaning member such as a cleaning blade.

  In such an image forming apparatus, a lubricant made of zinc stearate or the like is applied to the photosensitive drum in order to improve transferability and cleaning properties, and the lubricant on the photosensitive drum is leveled by a leveling member. In many cases, a film is formed.

JP 2010-276822 A

When the lubricant on the photosensitive drum is leveled with a leveling member, the tip of the leveling blade is usually urged toward the peripheral surface of the photosensitive drum by elastically biasing the tip of the leveling blade made of elastic rubber or the like. A configuration in which a lubricant film having a constant thickness is formed by allowing a certain amount of lubricant to pass between the portion and the peripheral surface of the photosensitive drum is adopted.
In such a configuration using the leveling blade, when the image forming apparatus is used for a long period of time, for example, several months or years, the leveling blade is in contact with the peripheral surface of the photosensitive drum via a lubricant. The tip of the wears out gradually.

As the wear of the tip of the leveling blade progresses, if the contact pressure of the tip of the leveling blade to the peripheral surface of the photosensitive drum decreases, the tip of the leveling blade will be less than when the wear is low. The amount of lubricant passing between the part and the peripheral surface of the photosensitive drum increases.
When the amount of lubricant passing through the leveling blade increases, the lubricant applied to the rotating photosensitive drum is separated from the peripheral surface of the photosensitive drum by the centrifugal force of the photosensitive drum, and the photosensitive drum The amount of lubricant that enters the inside of the developing unit disposed around the toner increases.

If the lubricant enters the developing unit for a long period of time and the amount of the lubricant mixed in the developer in the developing unit becomes excessive, it will affect the chargeability of the developer and the development. There is a risk of reducing the performance.
Although the example in the case of using a leveling blade has been described above, the same problem may occur when using a leveling member that wears with use over a long period of time.

  The present invention has been made in view of the above-described problems. In the configuration in which a lubricant is applied to an image carrier such as a photosensitive drum, the image carrier is maintained even if wear of the leveling member progresses over a long period of time. An object of the present invention is to provide an image forming apparatus capable of stably maintaining the quality of an image formed on a body.

In order to achieve the above object, an image forming apparatus according to the present invention transfers an image formed on a rotating image carrier to a transfer target, and a residue on the image carrier after transfer is transferred with a cleaning member. An image forming apparatus to be removed, the application means for applying a lubricant to the image carrier, a leveling member for leveling the coating thickness of the lubricant applied to the image carrier, and the leveling member Control means for reducing the amount of lubricant supplied to the image carrier by the application means based on an increase in the amount of wear at the portion in contact with the image carrier via the lubricant, and the control means Acquiring means for acquiring an allowable supply amount E of the lubricant to the image carrier, and supply amount estimating means for estimating a current supply amount X of the lubricant to the image carrier by the application unit, And the allowable supply amount E is increased as the wear amount of the leveling member increases. The relationship with the wear amount of the leveling member is set in advance so that the wear amount of the leveling member is increased. When the allowable supply amount E becomes larger, the supply amount of the lubricant to the image carrier is reduced to a smaller amount than before .

Also, the coating unit includes a rotary conveying member for conveying the lubricant obtained by scraping a solid lubricant to the application position of the lubricant to the image carrier, said solid lubricant on the rotation conveying member A pressing member that presses, and the supply amount estimating means may estimate the current supply amount X of the lubricant based on the magnitude of the pressing force by the pressing member.

Here, the supply amount estimation means may perform the estimation from information indicating a correspondence relationship between the magnitude of the pressing force by the pressing member and the current supply amount X of the lubricant.
Here, the supply amount estimation means may include detection means for detecting the magnitude of the pressing force by the pressing member.
Here, the detection means may be a sensor for detecting a pressing force acting on the rotary conveying member from the solid lubricant.

Et al is, the control unit may comprise a wear amount estimation means for estimating, based the current wear amount of the leveling member to a value indicative of the cumulative amount of rotation of the image bearing member.
In addition, the lubricant has a charging property, and the application unit includes a rotary conveyance member that conveys the lubricant from a lubricant supply source to a position where the lubricant is applied to the image carrier, and charged lubrication. A potential difference generating means for generating a potential difference between the rotary conveyance member and the image carrier so that an electrostatic force in a direction from the image carrier to the rotary conveyance member acts on the agent, and the control means includes: The supply amount of the lubricant may be reduced by generating the potential difference or changing the magnitude thereof.

Further, the coating unit includes a rotation conveyance member that conveys a lubricant from a lubricant supply source to a position where the lubricant is applied to the image carrier, and the control unit includes the image carrier and the rotation conveyance member. The supply amount of the lubricant may be reduced by changing the relative speed difference between the first and second lubricants.
The application means includes a rotary conveyance member that conveys the lubricant obtained by scraping the solid lubricant to a position where the lubricant is applied to the image carrier, and presses the solid lubricant against the rotary conveyance member. Pressing means, and the control means may reduce the supply amount of the lubricant by changing the pressing force by the pressing means.

Further, the control unit switches the reduction of the amount of lubricant supplied to the image carrier by the application unit from a first amount to a second amount smaller than the first amount. However, it may be executed during non-image formation other than during the image forming operation.
The leveling member may be made of an elastic body and elastically biased by the image carrier.

If comprised as mentioned above, even if wear of a leveling member progresses over a long period of time, the supply amount of the lubricant to the image carrier can be controlled to an appropriate amount based on the wear amount.
As a result, part of the lubricant after being leveled by the leveling member on the image carrier during rotation of the image carrier enters the inside of the developing unit disposed around the image carrier, for example. The lubricant that has entered can be prevented from accumulating to an extent that affects the developability, and the quality of the image formed on the image carrier over a long period of time can be stably maintained.

1 is a diagram illustrating an overall configuration of a printer. It is a figure which expands and shows the structure of the lubricant application part of a printer. It is sectional drawing of each member containing a brush roller and a solid lubricant. It is a graph which illustrates a mode that the supply amount of the lubricant by a brush roller falls as the use period of a printer becomes long. It is a graph which shows the example of the correspondence of solid lubricant supply amount and solid lubricant pressing force. (A) is a schematic diagram showing how the lubricant on the photosensitive drum is leveled by a new leveling blade, and (b) is a schematic diagram showing the leveling by the worn leveling blade. (C) is an enlarged schematic view showing a state where the tip of the leveling blade is worn. It is a block diagram which shows the structure of a control part. FIG. 6 is a diagram illustrating an example of a correspondence relationship between a cumulative photosensitive member rotation speed and a wear width of a leveling blade. It is a figure which shows the example of the correspondence of the wear width of a leveling blade, and a lubricant allowable supply amount. It is a figure which shows the example of the content of a control table. It is a flowchart which shows the content of lubricant supply control. It is a figure which shows the result of the image quality evaluation (fogging) at the time of performing durability test about the structure (Examples 1-4) which perform lubricant supply control, and the structure (comparative example) which is not performed. It is a figure which shows the structural example which provided the screw feed mechanism as a press means. It is a figure which shows the example of the correspondence of accumulated photoconductor rotation speed and solid lubricant pressing force.

Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described by taking a tandem color printer (hereinafter simply referred to as “printer”) as an example.
(1) Overall Configuration of Printer FIG. 1 is a diagram illustrating the overall configuration of the printer.
As shown in the figure, the printer forms an image by a known electrophotographic method, and includes an image forming unit 10, an intermediate transfer unit 20, a feeding unit 30, a fixing unit 40, and a control unit 50. When a print job execution instruction is received from an external terminal device (not shown) connected to a network (for example, a LAN), a color image composed of yellow, magenta, cyan, and black colors is received based on the instruction. Perform formation. Hereinafter, the reproduction colors of yellow, magenta, cyan, and black are represented as Y, M, C, and K, and Y, M, C, and K are added as subscripts to the numbers of the components related to the reproduction colors.

The image forming unit 10 includes image forming units 10Y, 10M, 10C, and 10K corresponding to each of Y to K colors and an exposure unit 11.
The image forming units 10Y to 10K include photosensitive drums 1Y, 1M, 1C, and 1K as image carriers that rotate in a direction indicated by an arrow A, and a charging unit 2Y that is disposed around the drum rotation direction A around the photosensitive drums 1Y, 1M, 1C, and 1K. 2M, 2C, 2K, developing units 3Y, 3M, 3C, 3K, cleaning units 4Y, 4M, 4C, 4K, lubricant application units 5Y, 5M, 5C, 5K, and static eliminating units 6Y, 6M, 6C , 6K, etc., and forms toner images of colors corresponding to the photosensitive drums 1Y to 1K.

The intermediate transfer unit 20 is a primary transfer arranged opposite to the photosensitive drums 1Y, 1M, 1C, and 1K via the intermediate transfer belt 21, the drive roller 22, the driven rollers 23, 24, and 25, and the intermediate transfer belt 21. Rollers 26 </ b> Y, 26 </ b> M, 26 </ b> C, and 26 </ b> K, and a secondary transfer roller 27 disposed to face the driving roller 22 with the intermediate transfer belt 21 interposed therebetween.
The intermediate transfer belt 21 is stretched by a driving roller 22, driven rollers 23 to 25, and primary transfer rollers 26 </ b> Y to 26 </ b> K, and travels in a direction indicated by an arrow Z by the rotational driving force of the driving roller 22.

The feeding unit 30 includes a paper feed cassette 31, a feeding roller 32, a transport roller pair 33, a timing roller pair 34, and the like.
The paper feed cassette 31 accommodates paper S as a recording sheet. The feeding roller 32 feeds the sheets S stored in the sheet feeding cassette 31 one by one to the transport path 39.
The transport roller pair 33 further transports the fed paper S on the transport path 39 downstream in the transport direction. The timing roller pair 34 takes a timing to send the conveyed paper S to a secondary transfer position 271 that is a contact position between the secondary transfer roller 27 and the intermediate transfer belt 21.

The fixing unit 40 presses the fixing roller and the pressure roller to ensure a fixing nip and heats the fixing roller with a heater to maintain a temperature necessary for fixing.
The control unit 50 converts an image signal from an external terminal device into an image signal for Y to K colors, and outputs a drive signal for driving a laser diode (not shown) for each color arranged in the exposure unit 11. Generate. In response to the generated drive signal, the exposure unit 11 emits a laser beam Ly for Y color, a laser beam Lm for M color, a laser beam Lc for C color, and a laser beam Lk for K color, respectively. The body drums 1Y to 1K are exposed and scanned.

Before receiving the exposure scanning, the photosensitive drums 1Y to 1K are uniformly charged by the charging units 2Y to 2K after being neutralized by the neutralizing units 6Y to 6K, and the photosensitive drums are exposed by the laser beams Ly to Lk. An electrostatic latent image is formed on the peripheral surface of 1Y to 1K.
The photosensitive drums 1Y to 1K have a charging characteristic of being charged with a negative (negative) polarity. The photosensitive drums 1Y to 1K are negatively charged by the charging units 2Y to 2K, and image formation is performed by the laser beams Ly to Lk. The part to be done is exposed.

Each electrostatic latent image is developed with toner by the developing units 3Y to 3K. Here, toner having a negative charge polarity is used, and a so-called reversal development method is used. The Y to K color toner images formed on the photosensitive drums 1Y to 1K are primarily transferred onto the intermediate transfer belt 21 by electrostatic force acting between the primary transfer rollers 26Y to 26K and the photosensitive drums 1Y to 1K. .
The image forming operations for the respective colors on the photosensitive drums 1Y to 1K are executed at different timings so that the toner images are transferred to the same positions on the intermediate transfer belt 21 in a superimposed manner. The respective color toner images transferred onto the intermediate transfer belt 21 are moved to the secondary transfer position 271 as the intermediate transfer belt 21 rotates.

  In accordance with the timing of the image forming operation, the sheet S is fed from the feeding unit 30 via the timing roller pair 34, and the sheet S includes the secondary transfer roller 27 and the intermediate transfer belt 21. The toner images on the intermediate transfer belt 21 are collectively transferred onto the sheet S at the secondary transfer position 271 by electrostatic force acting between the secondary transfer roller 27 and the intermediate transfer belt 21. Secondary transferred.

The sheet S that has passed the secondary transfer position 271 is conveyed to the fixing unit 40, and when passing through the fixing nip, the toner image is heated and pressurized to be fixed on the sheet S, and then passed through the discharge roller pair 40a. Discharged outside the machine.
Of the toner images on the photosensitive drums 1Y to 1K, residues including toner remaining on the photosensitive drums 1Y to 1K without being primarily transferred to the intermediate transfer belt 21 are cleaned by the cleaning units 4Y to 4K. The blades 41Y, 41M, 41C and 41K are removed.

  The lubricant is applied to the peripheral surfaces of the photosensitive drums 1Y to 1K after the residue is removed by the lubricant applying portions 5Y to 5K. The applied lubricant passes through the positions of the charging units 2Y to 2K and the developing units 3Y to 3K along the circumferential direction by the rotation of the photosensitive drums 1Y to 1K, and then passes to the cleaning units 4Y to 4K. Finally, the cleaning blades 41Y to 41K are supplied to contact portions with the photosensitive drums 1Y to 1K.

  As a result, friction between the cleaning blades 41Y to 41K and the photosensitive drums 1Y to 1K is reduced, and early cleaning of the cleaning blades 41Y to 41K can be prevented, and the cleaning performance can be improved over a long period. Longer life can be realized by suppressing the wear of the peripheral surfaces of the body drums 1Y to 1K. Further, the transferability is improved over a long period of time by providing a lubricant film between the peripheral surfaces of the photosensitive drums 1Y to 1K and the toner particles of the developed toner image on the photosensitive drums 1Y to 1K. be able to.

(2) Configuration of Lubricant Application Unit FIG. 2 is an enlarged view showing the configuration of the lubricant application unit 5Y of the image forming unit 10Y. The photosensitive drum 1Y, the cleaning blade 41Y, and the like arranged in the vicinity thereof Other members are also shown. Since all the image forming units have basically the same configuration, only the configuration of the image forming unit 10Y will be described below, and the description of the other image forming units 10M to 10K will be omitted.

As shown in the figure, the lubricant application unit 5Y is disposed downstream of the cleaning unit 4Y in the drum rotation direction A, and the cleaning unit 4Y and the lubricant application unit 5Y serve as one unit 9Y as a housing 190. Is detachably supported by the apparatus main body in a state of being accommodated in the apparatus.
The cleaning blade 41Y of the cleaning unit 4Y is obtained by processing polyurethane rubber into a plate shape, and is bonded to the holding metal plate 42Y by a hot melt adhesive here, and the tip of the cleaning blade 41Y is the photosensitive drum 1Y. The peripheral surface abuts in the direction opposite to the drum rotation direction A (counter direction), and scrapes the residual matter including the residual toner on the photosensitive drum 1Y. The scraped residue falls to the recovery screw 43Y in the housing 190, and is conveyed to a waste toner recovery box (not shown) by the recovery screw 43Y and recovered.

The lubricant application unit 5Y includes a brush roller 101, a solid lubricant 102, a holding member 103, a piezoelectric sensor 104, a support member 105, a compression spring 106, a leveling blade 107, a brush motor 108, and the like. .
FIG. 3 is a cross-sectional view taken along line D-D when the members of the brush roller 101 to the compression spring 106 are cut along the line DD. The horizontal direction in FIG. 3 is the axial direction (drum axial direction) of the photosensitive drum 1Y. Equivalent to.

  As shown in FIG. 3, the members such as the brush roller 101 and the solid lubricant 102 are elongated along the drum axial direction, and the axial length of the member is the main scan of the image forming area on the photosensitive drum 1Y. It is longer than the width in the direction (printing width). The elongated shape along the drum axis direction is the same for the leveling blade 107, the cleaning blade 41Y, and the housing 190 for housing them. A plurality of compression springs 106 are arranged at intervals along the drum axis direction, and three compression springs 106 are arranged here.

  As shown in FIGS. 2 and 3, the brush roller 101 includes a brush made of a plurality of conductive brush hairs (hereinafter referred to as “brush”) on a peripheral surface of a metal conductive material, here, an iron cored bar 111. 112 ”is provided, and is interposed between the photosensitive drum 1Y and the solid lubricant 102, and a portion of the brush fiber 112 facing the peripheral surface of the photosensitive drum 1Y is the portion of the photosensitive drum 1Y. A lubricant is applied (supplied) to the peripheral surface of the photosensitive drum 1Y in contact with the peripheral surface.

The contact position of the brush roller 101 with the peripheral surface of the photosensitive drum 1Y is the position 109 (FIG. 2) where the lubricant is applied to the photosensitive drum 1Y.
Both ends in the axial direction of the metal core 111 are rotatably supported by the housing 190, and rotate in the direction opposite to the drum rotation direction (direction indicated by arrow B) at the application position 109 by the driving force of the brush motor 108. .

The rotation speed of the brush roller 101 is such that the linear velocity along the rotation direction of the cored bar 111 at the tip of the bristle constituting the brush fiber 112 is a predetermined magnification with respect to a constant speed on the peripheral surface of the photosensitive drum 1Y. For example, it is specified to be 1.3 times. This magnification is called linear velocity ratio θ.
Here, the brush fiber 112 is a mixture of straight hair brushes and loop brushes in a predetermined ratio. The straight-hair brush is made of conductive acrylic, and has an electric resistance value of 10 ⁶ [Ω], a fiber thickness of 4 T (decitex), and a fiber density of 115 [KF / square inch]. On the other hand, the material of the loop brush is conductive polyester, the electrical resistance value is 10 ⁸ [Ω], the fiber thickness is 3 T [decitex], and the fiber density is 225 [KF / square inch].

The diameter of the cored bar 111 is 6 [mm], and the height of the bristle of the straight bristle brush and the loop brush constituting the brush fiber 112 is about 2.5 [mm]. Here, the brush fiber 112 is woven on a conductive base cloth (not shown) wound around the core metal 111. Since the thickness of the base cloth is about 0.5 mm, the diameter of the brush roller 101 is It is about 12 [mm].
A bias voltage Vbr from the bias power supply unit 80 (FIG. 1) is supplied to the metal core 111 of the brush roller 101, and the supply amount of the lubricant is controlled by varying the bias voltage Vbr. . This control will be described later.

The solid lubricant 102 is obtained by melt-molding a metal soap powder, and is made of a fatty acid metal salt. Here, zinc stearate having a negative triboelectric charging property is used.
This zinc stearate is suitable as a lubricant because of its high releasability (corresponding to a high pure water contact angle), low friction coefficient, high transferability and cleanability. However, it is not limited to this.

  For example, metal stearate such as aluminum stearate, copper stearate, magnesium stearate, zinc oleate, manganese oleate, iron oleate, copper oleate, magnesium oleate such as metal oleate, zinc palmitate, Metal lubricants such as copper palmitate and magnesium palmitate, metal linoleate such as zinc linoleate, and metal ricinoleate such as zinc ricinoleate and lithium ricinoleate can also be used as the lubricant.

  The holding member 103 is a plate-like member that holds the solid lubricant 102, and the support member 105 is a plate-like member that supports the compression spring 106 interposed between the housing 190 and both end portions in the drum axial direction. Is engaged with a through-hole 192 provided in the side portion 191 of the housing 190 in a vertical direction (a perspective direction with respect to the photosensitive drum 1Y) and supported so as to be movable in the vertical direction with respect to the housing 190.

The piezoelectric sensor 104 is formed of a piezoelectric element, and in the present embodiment, a film-shaped one is used, and is arranged in a state of being sandwiched between the holding member 103 and the support member 105.
Each of the three compression springs 106 has the same spring constant, and supports the urging force for pressing the solid lubricant 102 against the brush roller 101 in the direction indicated by the arrow C (the direction approaching the photosensitive drum 1Y). It is applied to the solid lubricant 102 via the member 105, the piezoelectric sensor 104, and the holding member 103.

The solid lubricant 102 pressed by the brush roller 101 is scraped off by each brush hair of the brush fiber 112 by the rotation of the brush roller 101. The scraped lubricant is conveyed to the application position 109 on the photosensitive drum 1Y by the rotation of the brush roller 101, and is supplied to the photosensitive drum 1Y.
The piezoelectric sensor 104 detects the urging force applied from the compression spring 106 as a pressing force of the solid lubricant 102 to the brush roller 101 and detects the detected pressing force [N / m] (hereinafter referred to as “solid lubricant pressing force”). An electric signal indicating the magnitude of “H” is output. The reason for detecting the solid lubricant pressing force H will be described later.

  The leveling blade 107 is formed by processing polyurethane rubber as an elastic body into a sheet shape, and is disposed at a position downstream of the brush roller 101 in the drum rotation direction, and its tip 171 is countered on the circumferential surface of the photosensitive drum 1Y. The lubricant supplied onto the photosensitive drum 1Y is passed between the peripheral surface of the photosensitive drum 1Y and the tip portion 171 elastically biased by the lubricant, so that the photosensitive drum 1Y Equalize the thickness of the lubricant on the circumference.

The leveling blade 107 is not limited to the configuration in which the leveling blade 107 is in contact with the photosensitive drum 1Y in the counter direction, but may be configured to be in contact with the reverse direction, that is, the so-called trailing direction.
In general, the hardness and rebound resilience of the leveling blade 107 are determined by the size of the width (contact width) of the tip portion 171 of the leveling blade 107 in contact with the peripheral surface of the photosensitive drum 1Y, and the leveling. This affects the degree of wear (edge wear) at the corners of the tip 171 of the blade 107.

  The higher the hardness of the leveling blade 107, the smaller the contact width and the lowering of the lubricant coating function, but there is a relationship that it becomes stronger against edge wear. On the other hand, the higher the rebound resilience of the leveling blade 107, the greater the contact width and the better the lubricant coating function, but weaker to edge wear. Therefore, it is necessary to set these two physical properties (hardness and impact resilience) within a range suitable for the apparatus configuration.

The rotating members such as the photosensitive drums 1Y to 1K and the intermediate transfer belt 21 are driven by the rotational driving force of the driving motor 12 (FIG. 1) and are maintained at a predetermined system speed.
(3) Lubricant Supply Amount by Brush Roller 101 FIG. 4 is a graph illustrating how the lubricant supply amount by the brush roller 101 decreases as the use period of the printer becomes longer. Is the cumulative photoreceptor rotation speed F, and the vertical axis is the solid lubricant supply amount G.

Here, the cumulative photosensitive member rotation speed F [krot] indicates the cumulative rotation number of any one of the photosensitive drums 1Y to 1K, here, the new photosensitive drum 1Y in kilo units, for example, 50 [krot]. ] Is 50,000 revolutions.
The solid lubricant supply amount G [mg] indicates the scraping amount [mg] from the solid lubricant 102 per unit rotation speed by the brush roller 101.

  The photosensitive drum 1Y and the brush roller 101 are in a relationship in which the brush roller 101 rotates when the photosensitive drum 1Y rotates, and the rotational speed of the photosensitive drum 1Y and the rotational speed of the brush roller 101 have a fixed relationship. As the cumulative photoconductor rotational speed F increases, the cumulative rotational speed of the brush roller 101 also increases in a fixed relationship. From this, it can be said that the cumulative photoconductor rotation speed F indicates the cumulative rotation speed of the brush roller 101.

As shown in the figure, the solid lubricant supply amount G decreases as the cumulative photosensitive member rotation speed F, that is, the cumulative rotation speed of the brush roller 101 increases, and the reduction rate (gradient of the graph). It can be seen that gradually decreases.
The reason why the solid lubricant supply amount G decreases as the cumulative photoconductor rotation speed F increases as described above is due to the relationship between the solid lubricant supply amount G and the solid lubricant pressing force H described above.

  That is, the solid lubricant pressing force H is a pressing force of the solid lubricant 102 to the brush roller 101 by the compression spring 106, and therefore, the compression spring 106 decreases as the extension amount of the compression spring 106 increases due to the Hooke's law. The amount of elongation increases as the solid lubricant 102 is scraped off by the brush roller 101 and worn down. For this reason, the solid lubricant pressing force H gradually decreases from when the solid lubricant 102 is new.

When the solid lubricant pressing force H decreases, the solid lubricant supply amount G, which is the scraping amount from the solid lubricant 102 by the brush roller 101, decreases, and the amount of lubricant supplied to the photosensitive drum 1Y decreases accordingly. Become.
FIG. 5 is a graph showing an example of the correspondence relationship between the solid lubricant supply amount G and the solid lubricant pressing force H. In FIG. 5, an example of a substantially proportional relationship is shown. It is done.

When the solid lubricant 102 is scraped off by the brush roller 101, the solid lubricant 102 is worn away, and the amount of elongation of the compression spring 106 increases accordingly, and the solid lubricant pressing force H decreases. The amount of scraping of the solid lubricant 102 by the brush roller 101 (solid lubricant supply amount G) is reduced by the amount by which the solid lubricant pressing force H is reduced.
By repeating a series of phenomena such as the abrasion of the solid lubricant 102, the reduction of the solid lubricant pressing force H, and the reduction of the scraping amount, the cumulative photoreceptor rotation speed F increases as shown in FIG. Along with this, the solid lubricant supply amount G gradually decreases.

As described above, the solid lubricant supply amount G decreases as the cumulative photoconductor rotation speed F increases. However, the rate of decrease (slope of the graph) of the solid lubricant supply amount G gradually decreases. Go.
This is because the amount of wear of the solid lubricant 102 per unit rotation speed by the brush roller 101 decreases as the cumulative photoconductor rotation speed F increases, so the rate of decrease in the solid lubricant pressing force H decreases. It is. Further, since the pressing force does not work when the compression spring 106 is fully extended, the amount of scraping of the solid lubricant 102 by the brush roller 101 is reduced more than before, but the brush fibers 112 of the rotating brush roller 101 are solid lubricant 102. This is because the scraping by the tip of the brush fiber 112 is continued with the scraping amount per unit rotation being substantially constant.

  When the cumulative photosensitive member rotational speed F shown in FIG. 4 is 0 [krot], the photosensitive drum 1Y or the brush roller 101 is new, and when the cumulative photosensitive member rotational speed F is 450 [krot], the photosensitive drum 1Y or brush is shown. Assuming that the life of the roller 101 has been reached, at least 160 [mg per unit rotation number of the brush roller 101 from the brush roller 101 to the photosensitive drum 1Y over a long period from the new product to the end of the life. ] More than about lubricant is supplied.

On the other hand, as described in the above section “Problems to be Solved by the Invention”, the tip 171 of the leveling blade 107 that is in contact with the peripheral surface of the photosensitive drum 1Y via the lubricant J is As the cumulative photoconductor rotational speed F increases, the leveling function of the lubricant decreases as it gradually wears due to friction with the peripheral surface of the photoconductor drum 1Y via the lubricant. .
FIG. 6A is a schematic diagram showing how the lubricant J on the photosensitive drum 1Y is leveled by a new leveling blade 107, and FIG. FIG. 6C is an enlarged schematic view showing a state where the tip of the leveling blade 107 is worn.

In the case of a new leveling blade 107 as shown in FIG. 6A, since the corner of the tip 171 is not worn, the contact surface with the peripheral surface of the photosensitive drum 1Y becomes extremely small, and the photosensitive drum The contact pressure with the peripheral surface of the body drum 1Y is increased.
As a result, a large number of particulate lubricants J supplied to the peripheral surface of the photosensitive drum 1Y are moved between the peripheral surface of the photosensitive drum 1Y and the front end portion 171 of the leveling blade 107 by the rotation of the photosensitive drum 1Y. When passing, a lubricant film Js spread in a film shape due to the large contact pressure is formed on the peripheral surface of the photosensitive drum 1Y.

The lubricant film Js tends to be in a continuous state in which each of the lubricants J is in close contact with each other, and the adjacent lubricants J are joined together by a cohesive force or the like, whereby the rotating photosensitive drum 1Y is centrifuged. It is difficult for a force to fly away from the photosensitive drum 1Y.
Further, even if the lubricant film Js on the photosensitive drum 1Y comes into contact with the developer carried on the developing roller 131 (FIG. 2) of the developing unit 3Y, the lubricant J is scraped off by contact with the developer. It is difficult for the developer to be mixed into the developer.

  On the other hand, as shown in FIG. 6B, in the case of the leveling blade 107 with advanced wear, the tip 171 becomes a flat surface 172 due to wear, and the width W of the flat surface 172 in the drum rotation direction (FIG. 6). If (c)) is defined as the wear width, the larger the wear width W, the greater the contact surface with the peripheral surface of the photosensitive drum 1Y than in the case of a new one. The contact pressure with the peripheral surface of the body drum 1Y decreases.

  As the decrease in the contact pressure increases, the coating function of the lubricant J by the leveling blade 107 decreases, the amount of the lubricant J passing through the leveling blade 107 increases, and the particulate lubricant J is reduced. It is often passed as it is. The particulate lubricant Jt (FIG. 6B) existing on the photosensitive drum 1Y that has passed through the leveling blade 107 is likely to be discontinuous with the adjacent lubricant J, and the coated lubricant Compared with the film Js, the connection between the lubricants J is likely to be weak, so that it is likely to fly away from the rotating photosensitive drum 1Y.

  Therefore, after the particulate lubricant J existing on the photosensitive drum 1Y passes through the leveling blade 107 and reaches the cleaning blade 41Y by the rotation of the photosensitive drum 1Y, a part of the lubricant J is photosensitive. It tends to occur from the body drum 1Y. Further, when the developer is in contact with the developer carried on the developing roller 131 of the developing unit 3Y, the lubricant J on the photosensitive drum 1Y is easily scraped off due to contact with the developer.

In this case, a part of the lubricant J existing on the photosensitive drum 1Y after passing through the leveling blade 107 is likely to be mixed into the developer in the developing unit 3Y.
The relationship between the wear width W of the leading end 171 of the leveling blade 107 and the cumulative photoreceptor rotation speed F is that the wear width W increases as the cumulative photoreceptor rotation speed F increases and the wear of the leading end 171 of the smoothing blade 107 progresses. Is in a widening relationship.

However, the relationship between the cumulative photoreceptor rotation speed F and the solid lubricant supply amount G is such that the reduction rate of the solid lubricant supply amount G is suppressed as the cumulative photoreceptor rotation speed F increases as shown in FIG. Because of this relationship, a certain amount of the lubricant J is supplied to the photosensitive drum 1Y even when the lifetime is approaching.
Accordingly, as the cumulative photoreceptor speed F increases, the wear width W of the tip 171 of the leveling blade 107 increases and the contact pressure decreases, whereas the lubricant J supplied to the photoreceptor drum 1Y by the brush roller 101 is reduced. Therefore, the amount of the lubricant J passing through the leveling blade 107 increases as the cumulative photoconductor rotation speed F increases.

Further, as the contact pressure of the leveling blade 107 to the photosensitive drum 1Y decreases, the amount of the lubricant J that passes through the leveling blade 107 in the form of particles also increases.
The amount of the lubricant J that passes through the leveling blade 107 in such a particulate state increases, and the lubricant J enters the developing portion 3Y for a long period of time, and is mixed into the developer. When the amount of J becomes excessive, the image quality is likely to deteriorate due to a decrease in the chargeability of the developer during the life of the photosensitive drum 1Y or the brush roller 101.

Further, not limited to development, for example, when the amount of the lubricant J attached to the charging wire 122 (FIG. 2) or the grid electrode 123 (FIG. 2) arranged on the shield 121 (FIG. 2) of the charging unit 2Y becomes excessive, There is also a possibility that the image quality is deteriorated due to the fluctuation of the surface potential of the photosensitive drum 1Y.
Therefore, in the present embodiment, the allowable supply amount (lubricant allowable supply amount E) of the lubricant to the photosensitive drum 1Y by the brush roller 101 is determined in advance according to the wear width W of the leveling blade 107. Keep it.

Then, the lubricant allowable supply amount E with respect to the wear width W of the leveling blade 107 is the current supply amount of lubricant from the brush roller 101 to the photosensitive drum 1Y (lubricant supply amount X) at regular intervals. It is determined whether or not the lubricant supply amount X is reduced more than before.
As a result, even if the wear width W increases due to the progress of wear of the leveling blade 107, the amount of lubricant supplied from the brush roller 101 to the photosensitive drum 1Y is reduced, so that it passes through the leveling blade 107 accordingly. The amount of the lubricant J is also reduced, so that it is possible to prevent the image quality from being deteriorated early in the middle of the lifetime and to maintain the image quality stably.

  The allowable lubricant supply amount E is determined so that the lubricant supply amount X exceeds the allowable lubricant supply amount E from the relationship between the wear width W of the smoothing blade 107 and the amount of lubricant J passing through the smoothing blade 107. If not, the supply amount that is assumed not to deteriorate the image quality due to the excessive supply of the lubricant J in the middle of the lifetime, in other words, the lubricant supply amount X exceeds the allowable lubricant supply amount E. The supply amount that is assumed to cause a decrease in image quality when J continues to be supplied is determined by experiments and the like.

Even if the reduction control of the lubricant J is performed, the cleaning blade 41Y is not worn at an early stage or the transferability is not deteriorated due to the lack of the lubricant by securing the necessary minimum amount of lubricant supply. .
In addition, it is conceivable to control the reduction of the lubricant J from when it is new, but in that case, in addition to (a) the solid lubricant supply amount G itself being reduced from the time of new, (b) leveling. Since the contact pressure of the blade 107 to the photosensitive drum 1Y is in a considerably high state, the two conditions that the amount of the lubricant J that can pass through the leveling blade 107 is reduced are overlapped. Since the supply of J is likely to be insufficient, the reduction control cannot be executed from the new time.

(4) Configuration of Control Unit 50 FIG. 7 is a block diagram showing the configuration of the control unit 50. In the figure, the piezoelectric sensors are 104Y to 104K. This indicates that the piezoelectric sensors 104 are arranged for the respective image forming units 10Y to 10K. The same applies to the brush motors 108Y to 108K and the brush rollers 101Y to 101K.

  As shown in the figure, the communication I / F unit 51 of the control unit 50 is an interface such as a LAN card or a LAN board for connecting to a network, here a LAN, and a print sent from an external terminal via the LAN. The job data is received and stored in the image memory 55. The print job data includes header information including the number of pages and the number of copies in addition to print data for image formation.

The ROM 53 stores a program for executing a print job.
The CPU 52 reads a necessary program from the ROM 53 and controls the image forming unit 10, the intermediate transfer unit 20, the feeding unit 30, the fixing unit 40, and the like, and based on the print job data stored in the image memory 55. Run a print job.
The RAM 54 serves as a work area for the CPU 52.

The accumulated rotational speed storage unit 56 stores data indicating the cumulative photosensitive body rotational speed F that is the cumulative rotational speed of the photosensitive drum 1Y up to the present.
The cumulative photosensitive member rotation speed F counts the number of pulses of the encoder pulse signal from the encoder 13 provided on the rotation shaft every time the drive motor 12 is driven from the start to the stop of the rotation. Thus, the rotational speed of the photosensitive drum 1Y obtained from the count value is updated by incrementing to the current cumulative photosensitive body rotational speed F. This update is executed by the CPU 52.

The blade wear width estimation unit 57 estimates the wear width W of the leveling blade 107 based on the wear width information stored in the wear width information storage unit 58.
As shown in FIG. 8, the wear width information is information indicating an example of a correspondence relationship between the cumulative photoconductor rotation speed F and the wear width W of the leveling blade 107. The blade wear width estimation unit 57 can estimate the current wear width W of the leveling blade 107 by reading the wear width W corresponding to the current cumulative photoreceptor rotation speed F from the wear width information.

  Although the figure shows an example of a relationship in which the wear width W of the leveling blade 107 increases proportionally as the cumulative photoconductor rotational speed F increases, the proportional relationship may not be achieved depending on the apparatus configuration. obtain. The wear width information is obtained in advance through experiments and stored in the wear width information storage unit 58. The wear width information can be a mathematical expression indicating a graph, a table format, or the like. The same applies to each piece of information such as the next allowable supply amount information.

Returning to FIG. 7, the allowable supply amount determination unit 59 determines the lubricant allowable supply amount E based on the allowable supply amount information stored in the allowable supply amount information storage unit 60.
The allowable supply amount information is information indicating an example of a correspondence relationship between the wear width W of the leveling blade 107 and the allowable lubricant supply amount E as shown in FIG. As shown in the figure, when the wear width W of the leveling blade 107 increases, the allowable lubricant supply amount E gradually decreases.

The allowable lubricant supply amount E indicates the scraping amount of the solid lubricant 102 by the brush roller 101 as described above, that is, the maximum allowable value of the lubricant supply amount to the photosensitive drum 1Y. Used as a threshold for no.
The reason why the allowable lubricant supply amount E as the threshold value is leveled and changed in accordance with the wear width W of the blade 107 is as follows.

That is, as shown in FIG. 4, the solid lubricant supply amount G, that is, the lubricant supply amount X supplied from the brush roller 101 to the photoconductor drum 1Y is increased as the accumulated photoconductor rotation speed F increases. As the reduction rate becomes smaller (the slope of the graph becomes smaller) and the lifetime approaches, the state of hardly changing continues.
The switching timing of the reduction control is preferably a time approaching the life to some extent because it is necessary to secure a sufficient amount of lubricant supply after the new article. Judgment of switching at a small time becomes particularly important.

The lubricant supply amount X is estimated by the current supply amount estimation unit 61 as will be described later. However, when the threshold value (lubricant allowable supply amount E) of the reduction control is set to a constant value (fixed value), the lubricant is supplied. It is necessary to set the constant value as a threshold within a range where the change width of the supply amount X is small.
This means that each time the estimated value of the lubricant supply amount X varies slightly, the magnitude relationship with the threshold value changes, and the switching to the reduction control should not be performed, or vice versa. It means that misjudgment is likely to occur.

  Therefore, the lubricant supply amount X that decreases as the life approaches the life, the wear width W of the smoothing blade 107 increases as the life approaches the life, that is, nears the life. It is set to a value that changes so as to reduce the allowable lubricant supply amount E as the wear width W increases. In this way, even if the lubricant supply amount X does not change so much, the difference from the lubricant supply amount X can be further increased, and the estimated value of the lubricant supply amount X varies somewhat. This is because the magnitude relationship does not change, and switching of the reduction control can be determined with higher accuracy.

As a result, switching of the reduction control can be performed at a more appropriate time, and the amount of the lubricant J passing through the leveling blade 107 is prevented from being excessive during the lifetime, and the leveling blade 107 is passed. Thus, it is possible to prevent the image quality from being deteriorated at an early stage due to a part of the large amount of lubricant J entering and accumulating in the developing unit 3Y.
In the configuration in which the change range of the lubricant supply amount X does not become extremely small even when the lifetime is approached, for example, the lubricant allowable supply amount E may be set to a constant value.

The allowable supply amount determination unit 59 refers to the allowable supply amount information, and reads the lubricant allowable supply amount E corresponding to the current wear width W of the leveling blade 107, thereby obtaining the current lubricant allowable supply amount E. Can be determined. Note that the allowable supply amount information is obtained in advance through experiments or the like and stored in the allowable supply amount information storage unit 60.
Returning to FIG. 7, the current supply amount estimation unit 61 estimates the current lubricant supply amount X by the brush roller 101 based on the current supply amount information stored in the current supply amount information storage unit 62.

Here, the current supply amount information corresponds to information indicating the relationship between the solid lubricant supply amount G and the solid lubricant pressing force H in FIG.
The current supply amount estimation unit 61 reads the solid lubricant supply amount G corresponding to the current solid lubricant pressing force H detected by the piezoelectric sensor 104 with reference to the current supply amount information, and reads the read solid lubricant supply The amount G is estimated as the current lubricant supply amount X. The current supply amount information is obtained in advance through experiments or the like and stored in the current supply amount information storage unit 62.

The supply amount control unit 63 is based on the magnitude relationship between the current lubricant supply amount X estimated by the current supply amount estimation unit 61 and the lubricant allowable supply amount E determined by the allowable supply amount determination unit 59. 101 controls the amount of lubricant supplied to the photosensitive drum 1Y.
In executing this control, the control information stored in the control table 64 is referred to.
FIG. 10 is a diagram showing an example of the contents of the control table 64. In the control table 64, information associating the accumulated photoconductor rotation speed F with the drum / brush potential difference ΔV is written.

Here, the drum / brush potential difference ΔV is supplied to the potential (drum surface potential) Vo (<0) at the coating position 109 on the peripheral surface of the photosensitive drum 1Y and from the bias power supply unit 80 to the core metal 111 of the brush roller 101. The difference from the bias voltage Vbr to be applied is shown.
As described above, the solid lubricant 102 has a negative frictional charging property. When the solid lubricant 102 is scraped off by the rotation of the brush roller 101, the scraped lubricant J is negatively charged by frictional contact with the brush fibers 112. Is done.

The negatively charged lubricant J is held by the brush fibers 112 and is conveyed toward the application position 109 on the photosensitive drum 1Y by the rotation of the brush roller 101, and from the brush roller 101 to the photosensitive drum at the application position 109. By moving to 1Y, supply to the photosensitive drum 1Y is performed.
The supply from the brush roller 101 to the photosensitive drum 1Y is performed mainly by the action of mechanical adhesion by rubbing when the brush fibers 112 rub against the peripheral surface of the photosensitive drum 1Y, but is negatively charged. If an electrostatic force due to an electric field generated between the brush roller 101 and the photosensitive drum 1Y is applied to the lubricant J, the supply amount can be increased or decreased.

Specifically, when the drum / brush potential difference ΔV (= Vo−Vbr)> 0, the negatively charged lubricant J has an electrostatic force in the direction from the brush roller 101 toward the photosensitive drum 1Y. Since it acts, the lubricant J easily moves from the brush roller 101 to the photosensitive drum 1Y, and the supply amount increases.
Conversely, if the drum / brush potential difference ΔV <0, the negatively charged lubricant J is subjected to an electrostatic force in the direction from the photosensitive drum 1Y toward the brush roller 101. It becomes difficult to move from the brush roller 101 to the photosensitive drum 1Y, and the supply amount decreases.

Therefore, the supply amount of the lubricant J from the brush roller 101 to the photosensitive drum 1Y can be increased or decreased by varying the drum / brush potential difference ΔV. In this embodiment, since the drum surface potential Vo after cleaning is substantially constant, for example, −100 [V], the bias voltage Vbr is variably controlled.
For example, in the control table 64 shown in FIG. 10, in the normal control, the drum / brush potential difference ΔV becomes 0 [V] regardless of the magnitude of the cumulative photoreceptor rotation speed F, that is, the bias voltage Vbr is −100 [. The bias power supply unit 80 is controlled so as to be V].

  On the other hand, in the reduction control in which the supply amount of the lubricant J is reduced as compared with the normal control, the drum / brush potential difference ΔV becomes −150 [V] in the range of the cumulative photoreceptor rotation speed F from 0 to 250 [krots]. That is, the bias power supply unit 80 is controlled so that the bias voltage Vbr becomes +50 [V], and the drum / brush potential difference ΔV is −300 [V] in the range where the cumulative photoreceptor rotation speed F exceeds 250 [krots]. That is, the bias power supply unit 80 is controlled so that the bias voltage Vbr becomes +200 [V]. The control of the bias power supply unit 80 is executed by the supply amount control unit 63.

  In the reduction control, the absolute value of the drum / brush potential difference ΔV is greater in the range exceeding 250 [krot] than in the range of 0 to 250 [krot] with the cumulative photoreceptor rotation speed F of 250 [krot] as a boundary. The larger value is that the wear width W of the leveling blade 71 is larger in the range exceeding 250 [krot] than in the range of 0 to 250 [krot], and is supplied to the photosensitive drum 1Y correspondingly. This is because it is necessary to increase the amount of lubricant J to be reduced.

  In the above description, the drum surface potential Vo after cleaning is regarded as substantially constant -100 [V] and the bias voltage Vbr is varied. For example, the drum surface potential Vo in the vicinity of the application position 109 of the photosensitive drum 1Y is set to the potential. Based on the detected drum surface potential Vo detected by a detection means such as a detection sensor, the bias voltage Vbr is set so that the drum / brush potential difference ΔV becomes a target value such as 0 [V] or −150 [V]. Variable control may be performed.

Further, since the amount of lubricant J supplied from the brush roller 101 to the photosensitive drum 1Y can be reduced as the drum surface potential Vo (<0) increases in absolute value, for example, the drum surface potential Vo required for reduction control is set. It is also possible to adopt a configuration in which the peripheral surface of the photosensitive drum 1Y is negatively charged by the charging unit 2Y.
Further, although the magnitude of the drum / brush potential difference ΔV is switched to two stages according to the magnitude of the accumulated photosensitive member rotation speed F, the present invention is not limited to this and may be switched to two or more multistages. For example, a configuration in which the absolute value of the drum / brush potential difference ΔV is gradually increased as the cumulative photoreceptor rotation speed F increases can be considered. Finer supply control can be executed.

As will be described later, the normal control is generally executed when the relationship of the current lubricant supply amount X ≦ the lubricant allowable supply amount E is satisfied, and the reduction control is executed when the relationship is not satisfied.
The magnitude of the drum / brush potential difference ΔV during normal control and during reduction control depends on the amount of the original lubricant J that should be supplied in normal time and the reduction control need not be executed. Based on the amount of lubricant J to be reduced and supplied when it occurs, an appropriate value is determined through experiments and the like, and is written in the control table 64.

(5) Lubricant Supply Control FIG. 11 is a flowchart showing the contents of the lubricant supply control for the image forming unit 10Y by the control unit 50, and is executed at the start of a job for each print job.
First, the current cumulative photoconductor rotation speed F is acquired (step S1).
This acquisition is performed by reading data indicating the accumulated photosensitive body rotation speed F stored in the accumulated rotation speed storage unit 56.

Next, the wear width W of the leveling blade 71 is estimated from the acquired cumulative photoreceptor rotation speed F (step S2). The wear width W is estimated by the blade wear width estimation unit 57.
Subsequently, the current lubricant allowable supply amount E is determined from the estimated wear width W of the leveling blade 71 (step S3). The determination of the allowable lubricant supply amount E is performed by the allowable supply amount determination unit 59.

The current solid lubricant pressing force H is acquired (step S4). The solid lubricant pressing force H is acquired by acquiring the current detection value by the piezoelectric sensor 104.
Next, the current lubricant supply amount X is estimated from the acquired solid lubricant pressing force H (step S5). The estimation of the lubricant supply amount X is executed by the current supply amount estimation unit 61.
Then, it is determined whether or not the lubricant supply amount X estimated in step S5 is equal to or less than the lubricant allowable supply amount E determined in step S3 (step S6).

If it is determined that the lubricant supply amount X ≦ the lubricant allowable supply amount E (“YES” in step S6), the amount of the lubricant J passing through the leveling blade 71 due to wear of the leveling blade 71 is currently excessive. If not, normal control is executed (step S7).
This normal control is executed by the supply amount control unit 63 by controlling the bias voltage Vbr so that the drum / brush potential difference ΔV becomes 0 [V] based on the contents of the control table 64.

Thus, when the lubricant supply amount X ≦ the lubricant allowable supply amount E at the start of the print job (“YES” in step S6), execution of the normal control is started from the start of the print job.
Then, it is determined whether or not the print job is finished (step S8).
If it is determined that the print job is not finished, that is, it is being executed (“NO” in step S8), the process returns to step S1, and steps S1 to S5 are executed.

If the lubricant supply amount X ≦ the lubricant allowable supply amount E (“YES” in step S6), the normal control is continued (step S7), and if the print job is being executed (“NO” in step S8). ]), The process returns to step S1 again.
When the print job is being executed and the relationship of the lubricant supply amount X ≦ the lubricant allowable supply amount E is satisfied, the normal control is continuously executed.

On the other hand, when the lubricant supply amount X> the lubricant allowable supply amount E (“NO” in step S6), the current amount of the lubricant J passing through the leveling blade 71 due to the increase in the wear width W of the blade 71 is Since it is excessive, the process proceeds to step S9.
In step S9, it is determined whether or not the current accumulated photoreceptor speed F is 250 [krot] or less.

If it is determined that the cumulative photoconductor rotation speed F ≦ 250 [krot] (“YES” in step S9), it is determined whether or not an image forming operation is being performed (step S10).
Here, the image forming operation is an operation in which a series of steps such as image formation by the image forming unit 10Y, specifically, charging, exposure, development, transfer, and the like are performed during execution of a print job. Show.

  The time when the image forming operation is not in progress (hereinafter referred to as “non-image forming time”) is when the print job is being executed but not during the image forming operation, and specifically, the first sheet from the start of the print job. The time immediately after the start of the job until the image forming operation (charging, etc.) on the paper S is started, and after the start of the image forming operation, n sheets when a plurality of sheets S are continuously fed at intervals. This indicates a time during which image formation is not performed until image formation on the next (n + 1) th sheet S is started after image formation on the sheet S is completed.

  For example, when an image to be formed on one sheet S is regarded as an image corresponding to one page, one print (image formation) job for executing printing on a plurality of sheets S is performed on the photosensitive drum 1Y. In other words, it can be called a job for sequentially forming images of a plurality of pages at time intervals in units of pages. It can be said that the time until.

Note that the photosensitive drum 1Y and the brush roller 101 rotate during execution of the print job both during the image forming operation and during the non-image formation.
If the current time immediately after the start of the job including the start time of the print job is determined as a non-image formation time (“NO” in step S10), the drum / brush potential difference ΔV is −150 based on the contents of the control table 64. Reduction control is performed to control to [V] (step S12), and the process proceeds to step S8. This reduction control is executed by the supply amount control unit 63.

Thus, at the start of the print job, the lubricant supply amount X> the lubricant allowable supply amount E (“NO” in step S6), and if the cumulative photoconductor rotation speed F ≦ 250 [krots] (step S9). And “YES”), the execution of the reduction control (ΔV = −150 V) is started from the start of the print job.
On the other hand, when it is determined that the time immediately after the start of the job has ended and the image forming operation has been started (“YES” in step S10), whether or not control other than reduction control (ΔV = −150 V) is currently being executed. Is determined (step S11).

Control other than the reduction control (ΔV = −150 V) indicates either normal control or reduction control (ΔV = −300 V). During the image forming operation, for example, a condition (X> E) for switching from normal control to reduction control (ΔV = −150 V) may be satisfied. In such a case, normal control is currently being executed. This is to judge this.
If the reduction control (ΔV = −150V) is currently being executed (“NO” in step S11), the process proceeds to step S12, and the reduction control (ΔV = −150V) continues even during the image forming operation. Executed.

On the other hand, when control other than the reduction control (ΔV = −150 V) is being executed (“YES” in step S11), the process returns to step S10.
When the image forming operation is being performed (“YES” in step S10) and control other than the reduction control (ΔV = −150 V) is being performed (“YES” in step S11), the non-image is started from the image forming operation. The process waits to proceed to the next step S12 until switching at the time of formation.

When it is determined that the image forming operation has been switched to non-image forming (“NO” in step S10), the control other than the reduction control (ΔV = −150 V) is switched to the reduction control (ΔV = −150 V) and executed ( Step S12), the process proceeds to step S8.
As described above, it is the photosensitive drum 1Y that prohibits the switching from the control other than the reduction control (ΔV = −150V) to the reduction control (ΔV = −150V) during the image forming operation and is executed during the non-image formation. This is to prevent the occurrence of uneven application of the lubricant J due to fluctuations in the supply amount of the lubricant J during the image forming operation and to suppress the influence on the transferability due to the occurrence of the uneven application. .

Thereafter, the print job is being executed (“NO” in step S8), the relationship of lubricant supply amount X> lubricant allowable supply amount E is satisfied (“NO” in steps S1 to S5 and S6), and cumulative photosensitivity. If the body rotational speed F ≦ 250 [krot] (“YES” in step S9), the reduction control is continuously executed during the image forming operation and during the non-image forming (step S11).
If the relationship of lubricant supply amount X> lubricant allowable supply amount E is satisfied during execution of the print job and normal control (“NO” in step S6), that is, normal When the condition for switching from control to reduction control (ΔV = −150 V) is satisfied, the cumulative photoconductor rotation speed F ≦ 250 [krots] (“YES” in step S9), and if the image forming operation is in progress (step If “YES” in S10, “YES” in S11), even if lubricant supply amount X> lubricant allowable supply amount E, the normal control is continued as it is, and switching is performed during non-image formation (in step S10). “NO”), the normal control is switched to the reduction control (ΔV = −150 V), and the reduction control is executed (step S12).

If the relationship of the lubricant supply amount X ≦ the lubricant allowable supply amount E is restored during the execution of the print job (“YES” in step S6), the normal control is executed by switching from the reduction control to the normal control. Then (step S7), the process proceeds to step S8.
During the execution of the print job, the allowable lubricant supply amount E decreases due to an increase in the wear width W of the leveling blade 71, and at the same time, the lubricant supply amount X decreases due to a decrease in the solid lubricant pressing force H. This is because the magnitude relationship between the lubricant supply amount X and the lubricant allowable supply amount E may be changed during the execution of the job as the cumulative photoreceptor rotation speed F increases.

On the other hand, when it is determined that the current relationship of accumulated photoconductor rotational speed F> 250 [krot] is satisfied (“NO” in step S9), it is determined whether or not an image forming operation is currently being performed (step S13). .
For example, if the current time is immediately after the start of the job, it is determined that a non-image is being formed (“NO” in step S13), and the drum / brush potential difference ΔV becomes −300 [V] based on the contents of the control table 64. Thus, the reduction control is performed (step S15), and the process proceeds to step S8. This reduction control is executed by the supply amount control unit 63.

As a result, when the print job starts, the lubricant supply amount X> the lubricant allowable supply amount E (“NO” in step S6), and if the cumulative photoconductor rotation speed F> 250 [krots] (step S9). And “NO”), the execution of the reduction control (ΔV = −300 V) is started from the start of the print job.
On the other hand, if it is determined that the image forming operation is being performed (“YES” in step S13), it is determined whether or not a control other than the reduction control (ΔV = −300 V) is currently being executed (step S14).

  Control other than the reduction control (ΔV = −300 V) indicates either normal control or reduction control (ΔV = −150 V). During the image forming operation, for example, a condition (F> 250) for switching from the reduction control (ΔV = −150 V) to the reduction control (ΔV = −300 V) may be satisfied. This is because the control (ΔV = −150 V) is being executed, and this is judged.

If the reduction control (ΔV = −300V) is currently being executed (“NO” in step S14), the process proceeds to step S15, and the reduction control (ΔV = −300V) continues even during the image forming operation. Executed.
On the other hand, when control other than the reduction control (ΔV = −300 V) is being executed (“YES” in step S14), the process returns to step S13.

When control other than the reduction control (ΔV = −300 V) is being performed during the image forming operation, the process waits for the next step S15 to be performed during the period from the image forming operation to when switching to non-image formation. Similarly to the above, this is to suppress the influence on the transferability and the like due to the fluctuation of the supply amount of the lubricant J to the photosensitive drum 1Y during the image forming operation.
When it is determined that the image forming operation has been switched to non-image forming (“NO” in step S13), the control other than the reduction control (ΔV = −300V) is switched to the reduction control (ΔV = −300V) and executed ( Step S15), the process proceeds to step S8.

  Thereafter, the print job is being executed (“NO” in step S8), the relationship of the lubricant supply amount X> the lubricant allowable supply amount E is satisfied (“NO” in steps S1 to S5 and S6), and the cumulative photosensitivity. If the body rotation speed F> 250 [krot] (“NO” in step S9), the reduction control (ΔV = −300 V) is continuously executed during both the image forming operation and the non-image forming (step S15).

  It should be noted that when the print job is being executed and the reduction control (ΔV = −150 V) is being executed, the cumulative photosensitive member rotation speed F exceeds 250 [krots] (“NO” in step S9), that is, the reduction. If the condition (F> 250) for switching from control (ΔV = −150 V) to reduction control (ΔV = −300 V) is satisfied, “YES” in step S13 and “YES” in S14. ), The reduction control (ΔV = −150 V) is continued as it is, and when the non-image formation is switched (“NO” in step S13), the reduction control (ΔV = −300 V) is performed instead of the reduction control (ΔV = −150 V). It is executed (step S15).

If the relationship of lubricant supply amount X ≦ lubricant allowable supply amount E is satisfied during the execution of the print job (“YES” in step S6), the control is switched to normal control (step S7). ).
Until the end of the print job is determined, the above process is repeatedly executed. When the end of the print job is determined ("YES" in step S8), the lubricant supply control is ended.

In the above description, every time “NO” is determined in step S8 from the start to the end of the print job, lubricant supply amount X> lubricant allowable supply amount E is satisfied by the processing in steps S1 to S6. Each time the magnitude relationship is determined and the determination result is obtained, the normal control and the reduction control are switched and executed based on the result. However, the present invention is not limited to this.
For example, the processing after step S1 is executed only once at the start of print job execution, and any one of normal control, reduction control (ΔV = −150 V), and reduction control (ΔV = −300 V) is executed. It may be determined that the control is to be performed, and the determined control may be continuously executed until the end of the print job. During execution of the print job, it is not necessary to repeatedly execute processes such as estimation and determination in steps S1 to S6, and the lubricant supply control can be simplified.

  Considering that the wear width W of the leveling blade 71 gradually increases over a long period of time, a specific timing, for example, when the accumulated photosensitive member rotation speed F is the first rotation and 1 [krot ], I.e., at the time of reaching the 1000th rotation, the 2000th rotation,..., Which of the normal control and the reduction control is to be executed by the processing in step S1 and subsequent steps. The determined control may be continuously executed until the timing is reached. Of the normal control and the reduction control, the control to be executed only needs to be executed at a specific timing, and the lubricant supply control can be further simplified.

The specific timing is not limited to the above, and may be, for example, every 10 [krot] larger than 1 [krot], every 0.1 [krot] smaller than 1 [krot], or every print on one sheet S. .
Further, the lubricant supply control may be executed individually for each of the image forming units 10Y to 10K, or the control to be executed is determined for any one image forming unit, and the determined control is performed. Can be applied to all image forming units.

(6) Effects of Lubricant Supply Control FIG. 12 shows image quality evaluation (fogging) when a durability experiment is performed for the configuration (Examples 1 to 4) for executing the lubricant supply control and the configuration for not executing (Comparative Example). It is a figure which shows the result.
The experimental machine used was a bizhub PRESS C8000 (A4 paper: 80 sheets / minute) manufactured by Konica Minolta, modified to the configuration shown in FIG. The solid lubricant 102 was made of zinc stearate. As the compression spring 106, one having a spring constant at which a pressing force of 2.0 [N / m] acts was used.

The cleaning blades 41Y to 41K use polyurethane rubber, have a JIS-A hardness of 72 degrees and a rebound resilience of 25%, a contact force of 25 [N / m], and a contact angle of 15 [°]. It was.
The endurance condition is that a character image corresponding to a printing rate of 5 [%] is intermittently printed in an environment of a room temperature of 23 [° C.] and a humidity of 65 [% RH], and among the photosensitive drums 1Y to 1K, the photosensitive drum The conditions were set to execute printing until the accumulated rotational speed F of 1Y reached 500 [krots].

The control parameter in the figure shows a control object for varying the supply amount of the lubricant J. In the first and second embodiments, the control parameter is the drum / brush potential difference ΔV.
In the third embodiment, the linear velocity ratio θ is used as a control parameter instead of the drum / brush potential difference ΔV, and in the fourth embodiment, the lubricant pressing force R is used as a control parameter.
Here, the linear velocity ratio θ of Example 3 is the ratio of the rotational speed of the brush roller 101 to the circumferential speed of the photosensitive drum 1Y (corresponding to the circumferential speed ratio) as described above, and the linear velocity ratio θ. Since the contact area in the rotation direction of the brush roller 101 with the peripheral surface of the photosensitive drum 1Y per unit time decreases as the value decreases, the supply amount of the lubricant J decreases.

The lubricant pressing force R in Example 4 is the pressing force of the solid lubricant 102 to the brush roller 101. In the configuration in which pressing means capable of adjusting the pressing force are separately arranged, the pressing force R The case where a means is set as a control target is shown.
FIG. 13 is a diagram illustrating a configuration example in which a screw feeding mechanism 200 is provided as a pressing unit.
As shown in the figure, the screw feed mechanism 200 is provided on the rotation shaft 231 of the screw feed motor 203 in the screw holes 232 provided at both axial ends of the support member 201 that supports the compression spring 106. It is made by screwing screws.

  By rotating and driving the screw feed motor 203, the distance between the support member 201 and the cored bar 111 of the brush roller 101 is changed. As this distance increases, the length of the compression spring 106 increases and the restoring force of the compression spring 106 decreases. Therefore, the supply amount of the lubricant J is reduced. Note that the mechanism is not limited to the screw feed mechanism, and a mechanism that converts the rotational driving force of a motor such as a rack and pinion into a linear motion can also be used.

In the configuration in which the linear velocity ratio θ is varied and the configuration in which the lubricant pressing force R is varied, for example, the lubricant J can be applied to a material having no charging characteristics. Further, the linear velocity ratio θ may be determined by a relative velocity difference between the photosensitive drum 1Y and the brush roller 101. For example, one or the other may be slower or faster than before.
Returning to FIG. 12, the comparative example shows a case where none of the drum / brush potential difference ΔV, the linear velocity ratio θ, and the lubricant pressing force R are controlled.

  In Example 1, the cumulative rotational speed F is divided into the first half of 0 to 250 [krots] and the second half of 250 to 500 [krots]. In the first half, the lubricant J is separated from the time when the cumulative rotational speed F is 180 [krots]. Supply control is switched from normal control to reduction control (ΔV = −150 V), and in the second half, the reduction control (ΔV = −150 V) to reduction control (ΔV = −300 V) at the time when the cumulative rotational speed F is 350 krot ). This means that the relationship of lubricant supply amount X> lubricant allowable supply amount E was satisfied in step S6 of FIG. 11 when the cumulative rotational speed F was 180 [krot] and 350 [krot]. Equivalent to.

The drum / brush potential difference ΔV is controlled by variably controlling the bias voltage Vbr by the bias power supply unit 80.
In the second embodiment, the supply control of the lubricant J is switched from the normal control to the reduction control (ΔV = −300 V) when the cumulative rotational speed F is 180 [krot] in the first half, and is reduced at the time of 350 [krot] in the second half. The control (ΔV = −300V) was switched to the reduction control (ΔV = −600V).

In the third embodiment, the supply control of the lubricant J is reduced from the normal control (linear velocity ratio θ = 1.3) to the reduction control (linear velocity ratio θ = 1.0) when the cumulative rotation speed F is 180 [krot] in the first half. In the latter half of 350 [krot], the reduction control (linear velocity ratio θ = 1.0) was changed to the reduction control (linear velocity ratio θ = 0.7).
The linear speed ratio θ is controlled by variably controlling the rotational speed of the brush motor 108Y with respect to the photosensitive drums 1Y to 1K rotating at a constant system speed to a rotational speed corresponding to the linear speed ratio θ.

In the fourth embodiment, the supply control of the lubricant J is reduced from the normal control (lubricant pressing force R = 1.6) to the reduction control (lubricant pressing force R = 1) when the cumulative rotation speed F is 180 [krot] in the first half. .3) and at the time of 350 [krot] in the latter half, the reduction control (lubricant pressing force R = 1.3) was switched to the reduction control (lubricant pressing force R = 0.8).
The lubricant pressing force R is controlled by controlling the amount of rotation of the screw feed motor 203 so that the pressing force detected by the piezoelectric sensor 104Y matches the lubricant pressing force R.

“Before control” and “after control” of each control parameter indicate immediately before and after the control switching, and “after durability” of the lubricant pressing force R is the time when the first half ends and the second half ends. The actual measurement value of the lubricant pressing force R at each time point is shown.
The blade wear width after durability indicates the wear width W of the leveling blade 71 at the time when the first half is finished and at the time when the second half is finished.

  The developer mixing amount after the endurance is the amount of the lubricant J mixed in the developing unit 3Y in the first half with respect to the Y developer amount stored in the developing unit 3Y at the time when the first half is finished. In the latter half, the ratio of the amount of lubricant J mixed into the developing unit 3Y through both the first half and the latter half with respect to the amount of Y developer accommodated in the developing unit 3Y at the end of the second half Is shown.

The image quality evaluation after endurance shows the result of the fog evaluation after the end of the first half and after the end of the second half.
This fog is image noise generated when the charge amount of the toner in the developer decreases due to the mixing of the lubricant J. The fog evaluation is performed after the end of the first half and after the end of the second half. In addition to the above-mentioned durability, when a white solid image is printed in an environment of room temperature 30 [° C.] and humidity 85 [% RH], the occurrence of fogging in the reproduced image of the white solid image should be visually confirmed. Made by.

If there is no noise image that can be judged to be fogging even when visually observed, it is ◯ (good), and if it is a noise image that can be judged faintly by visual observation, Δ (acceptable range), it is clearly recognized as a noise image. In the case, it was set as x (defect).
If the evaluation result of the figure is seen, in Examples 1-4, there is no x (defect), and the fog is within an allowable range over the range of the cumulative rotational speed F from 0 to 500 [krot]. The developer mixing amount that causes fogging is also suppressed to 0.392 [wt%] or less.

  Further, comparing the first and second embodiments, the developer mixing amount in the second embodiment is considerably smaller than that in the first embodiment. This is because the drum / brush potential difference ΔV is larger in absolute value in the reduction control in the second embodiment than in the first embodiment. Therefore, the brush roller 101 is affected by the action of the electric field generated by the drum / brush potential difference ΔV. This is probably because the supply amount of the lubricant J to the photosensitive drum 1Y is greatly reduced.

As described above, from the evaluation results of Examples 1 to 4, even if any of drum / brush potential difference ΔV, linear velocity ratio θ, and lubricant pressing force R is used as a control parameter, the effect of maintaining stable image quality is obtained. You can see that
On the other hand, in the comparative example, the developer mixing amount causing fogging is 0.675 [wt%], which is 1.7 times that of Example 1, and the fogging is poor (×). I understand that.

This is because, in the comparative example, the reduction control of the lubricant J is not executed, so that the amount of the lubricant J passing through the leveling blade 71 whose wear has progressed over a long period of time increases, and the developer in the developing unit 3Y is increased. This is probably because the amount of the lubricant J mixed in is too large, and the amount of toner having a reduced charge amount is increased among the toners in the developer.
In the above, the image quality evaluation result for the Y color has been described, but it has also been confirmed that the same evaluation was obtained for the other M to K colors.

As described above, in the present embodiment, the supply amount of the lubricant J from the brush roller 101 to the photosensitive drums 1Y to 1K is controlled based on the wear width W indicating the wear amount of the leveling blade 71. That is, when the wear width W increases, reduction control is performed to reduce the supply amount of the lubricant J more than before.
Thereby, even if the wear amount of the leveling blade 71 increases over a long period of time, the supply amount of the lubricant to the photosensitive drums 1Y to 1K can be reduced to an appropriate amount based on the increase in the wear amount.

  Accordingly, a part of the lubricant J after being leveled by the leveling blade 71 on the photosensitive drums 1Y to 1K during the rotation of the photosensitive drums 1Y to 1K is disposed around the photosensitive drums 1Y to 1K. An image formed on the photosensitive drums 1Y to 1K over a long period of time can be prevented from entering the developing units 3Y to 3K and accumulating the lubricant J that has entered the developing units 3Y to 3K to an extent that affects the developability. The quality of can be kept stable.

  Also, switching of the lubricant supply control, specifically, switching from normal control to reduction control, and switching from reduction control (ΔV = −150 V) to (ΔV = −300 V) is not performed during the image forming operation. (Prohibited) Since it is executed at the time of non-image formation, the supply amount of the lubricant J to the photosensitive drums 1Y to 1K is fluctuated, so that the first amount is changed to the second amount smaller than this during the image forming operation. It is possible to prevent the transfer property and the cleaning property from being affected without decreasing. When there is almost no influence on the transfer property and the cleaning property, the control switching can be executed during the image forming operation.

In the above experiment, the control parameter is any one of the drum / brush potential difference ΔV, the linear velocity ratio θ, and the lubricant pressing force R. However, the control parameter is not limited to this. For example, a combination of a plurality of these is used as a control parameter. It may be configured to control.
The present invention is not limited to the image forming apparatus, and may be a lubricant application method that executes supply control of the lubricant J. The method may be a program executed by a computer. Furthermore, the program according to the present invention can be read by a computer such as a magnetic disk such as a magnetic tape or a flexible disk, an optical recording medium such as a DVD-ROM, DVD-RAM, CD-ROM, CD-R, MO, or PD. It can be recorded on various recording media, and may be produced, transferred, etc. in the form of the recording medium, or in the form of a program, including wired and wireless networks including the Internet, broadcasting, telecommunications lines, In some cases, the data is transmitted and supplied via satellite communication or the like.

<Modification>
As described above, the present invention has been described based on the embodiment. However, the present invention is not limited to the above-described embodiment, and the following modifications may be considered.
(1) In the above embodiment, the current detection value by the piezoelectric sensor 104 is acquired as the solid lubricant pressing force H (step S4), but the method of acquiring the solid lubricant pressing force H is not limited to this. .

For example, as shown in FIG. 14, a correspondence relationship between the accumulated photosensitive member rotation speed F and the solid lubricant pressing force H is obtained in advance, and the solid lubrication with respect to the current accumulated photoreceptor rotation number F is referred to by referring to this correspondence relationship. A configuration in which the magnitude of the agent pressing force H is acquired can also be taken.
The present invention can be applied when the rotational speed of the photosensitive drum 1Y and the rotational speed of the brush roller 101 are constant, and the cost can be reduced because the piezoelectric sensor 104 is not necessary.

Further, the wear width W of the leveling blade 71 is estimated from the accumulated photoreceptor rotation speed F (step S2), and the allowable lubricant supply amount E is determined from the estimated wear width W (step S3). If the relationship between the cumulative photoreceptor speed F and the allowable lubricant supply amount E is obtained in advance, the estimation of the wear width W can be omitted and the lubricant supply control can be further simplified.
Further, if the relationship between the cumulative photosensitive member rotation speed F and the solid lubricant supply amount G shown in FIG. 4 can be obtained in advance by experiments or the like, the current state is based on the relationship instead of steps S4 and S5 in FIG. The current lubricant supply amount X can also be obtained by determining the solid lubricant supply amount G with respect to the cumulative photoreceptor rotation speed F. When this configuration is adopted, it is not necessary to acquire the solid lubricant pressing force H (step S4), and the lubricant supply control can be simplified.

Further, the example in which the solid lubricant supply amount G decreases as the cumulative photoconductor rotation speed F increases has been described, but the present invention is not limited to this.
For example, if a configuration is provided in which a pressing mechanism is provided that increases the pressing force of the solid lubricant 102 against the brush roller 101 as the cumulative photosensitive member rotational speed F increases, the cumulative photosensitive member rotational speed F is large or small. It is also possible to keep the solid lubricant supply amount G constant.

When this configuration is adopted, there is no need to estimate the current lubricant supply amount X, so that the lubricant supply amount X is a constant value, and the magnitude relationship between the lubricant supply amount X and the current lubricant allowable supply amount E is as follows. What is necessary is just to judge (step S6).
(2) In the above embodiment, the configuration example has been described in which the lubricant supply control is switched between the normal control and the reduction control based on the current magnitude relationship between the lubricant supply amount X and the allowable lubricant supply amount E. Not limited to this.

It is only necessary to suppress an increase in the amount of the lubricant J passing through the leveling blade 71 as the wear amount of the leveling blade 71 increases. For example, until the wear level of the leveling blade 71 exceeds a predetermined threshold value. It is also possible to adopt a configuration in which normal control is executed and switched to reduction control when a predetermined threshold is exceeded. The predetermined threshold value can be obtained in advance from an experiment or the like.
In the case of adopting this configuration, if the cumulative photoconductor rotational speed F is averaged and taken as an index value of the wear amount of the blade 71, the lubricant supply control is switched based on the magnitude relationship between the cumulative photoconductor rotational speed F and a predetermined threshold value. It is also possible to simplify the switching control.

Note that the index value of the wear amount of the leveling blade 71 is not limited to the cumulative photosensitive member rotation speed F. For example, the cumulative driving time of the photosensitive drum 1Y, the cumulative travel distance, the cumulative rotational speed of the brush roller 101, and the cumulative driving time. The cumulative travel distance, the cumulative number of prints, etc. can also be used.
(3) In the above embodiment, the solid lubricant pressing force H is detected by the piezoelectric sensor 104. However, the present invention is not limited to this method.

For example, the correspondence between the displacement amount of the compression spring 106 and the solid lubricant pressing force H is obtained in advance, the displacement amount of the compression spring 106 is detected, and the solid lubricant pressing force H corresponding to the detected displacement amount is obtained. You can also take a way to get.
As a method for detecting the amount of displacement of the compression spring 106, for example, there is a method using a Hall element used for linear position detection. Specifically, a magnet to be detected by the Hall element is mounted on the support member 105, and the compression spring 106 is extended, so that the displacement from the Hall element is proportional to the amount of displacement of the support member 105 in the direction indicated by the arrow C. The magnitude of the output value that is output can be detected as the amount of displacement of the compression spring 106.

(4) In the above embodiment, the configuration example in which the solid lubricant 102 as the lubricant supply source is scraped with the brush roller 101 has been described, but the present invention is not limited to this. For example, the powdery lubricant contained in the case can be used as a lubricant supply source, and the powdery lubricant can be wound up from the case by the brush roller 101 and supplied to the photosensitive drum.
Further, the example has been described in which the brush roller 101 is used as the rotary conveyance member that conveys the lubricant J from the lubricant supply source to the application position 109 on the photosensitive drums 1Y to 1K as the image carrier while holding the lubricant J. It is not limited to a brush-like rotating member. For example, a roller around which a non-woven fabric is wound, a sponge-like one, a roller having a rough surface such as fine irregularities, or the like can also be used.

  (5) In the above embodiment, an example in which the image forming apparatus according to the present invention is applied to a tandem type color printer has been described. However, the present invention is not limited to this. Regardless of the function of executing color image formation or the function of executing monochrome image formation, any configuration that applies a lubricant to the peripheral surface of a rotating image carrier, for example, a copier, FAX, MFP (Multiple Function) Peripheral) etc.

In addition, the configuration example in which the cleaning blades 41Y to 41K are used as cleaning members that contact the photosensitive drums 1Y to 1K and remove residues such as residual toner on the photosensitive drums 1Y to 1K after the primary transfer has been described. It is not limited to a shape, and may be another shape.
Further, the leveling blade 107 is used as the leveling member for leveling the lubricant J supplied onto the photosensitive drum 1 for each of the photosensitive drums 1Y to 1K. However, the present invention can be applied to other shapes. Further, the leveling member itself is an elastic body and is elastically urged to the photosensitive drum 1Y. However, the present invention is not limited to this. For example, the leveling member may be urged by an elastic force of an elastic member such as a spring. good.

Moreover, although the structural example using the compression spring 106 as an elastic member was demonstrated as a press means which presses the solid lubricant 102 to the brush roller 101, as long as it is an elastic member, you may use things other than a spring.
Furthermore, in the above-described embodiment, the configuration example in which the image carrier is the photosensitive drum has been described. However, the configuration is not limited to the drum shape, and may be a belt shape, for example.

In addition, the configuration example in which the photosensitive drums 1Y to 1K are the image carrier and the intermediate transfer belt 21 to which the image on the photosensitive drum is transferred has been described, is not limited thereto.
For example, an intermediate transfer member such as the intermediate transfer belt 21 is regarded as an image carrier, a recording sheet on which an image on the intermediate transfer belt 21 is transferred is regarded as a transfer target, and a lubricant is applied to the intermediate transfer member. The present invention can also be applied to a configuration in which a cleaning unit for cleaning a residue such as toner on the intermediate transfer member with a cleaning member such as a cleaning blade is disposed. When an excessive amount of lubricant is supplied to the intermediate transfer member, it is possible to prevent the excessively supplied lubricant from being transferred to the developing unit or the like via the photosensitive drum in contact with the intermediate transfer member.

In the case of an image forming apparatus that does not include an intermediate transfer member, a photosensitive drum can be an image carrier, and a recording sheet onto which an image on the photosensitive drum is transferred can be a transfer target.
The material, size, shape, voltage, speed, rotation speed, electrical resistance value, pressing force, supply amount, wear width, linear velocity ratio, number of prints, sensor type, etc. for each of the above members However, the material, size, etc. suitable for the device configuration are determined. Similarly, the correspondence relationship between the solid lubricant supply amount G and the solid lubricant pressing force H, the correspondence relationship between the cumulative photoreceptor rotation speed F and the wear width W of the leveling blade 107, and the wear width W of the leveling blade 107 The correspondence relationship with the allowable lubricant supply amount E is not limited to the above example, and the relationship according to the apparatus configuration is determined.

  Further, the contents of the above embodiment and the above modification may be combined as much as possible.

  The image forming apparatus according to the present invention is useful as a technique for applying a lubricant to an image carrier.

1Y, 1M, 1C, 1K Photosensitive drum 3Y, 3M, 3C, 3K Developing unit 5Y, 5M, 5C, 5K Lubricant application unit 41Y, 41M, 41C, 41K Cleaning blade 50 Control unit 56 Cumulative rotation speed storage unit 57 Blade Wear width estimation unit 59 Allowable supply amount determination unit 61 Current supply amount estimation unit 63 Supply amount control unit 80 Bias power supply unit 101 Brush roller 102 Solid lubricant 104 Piezoelectric sensor 106 Compression spring 107 Leveling blade 108 Brush motor 109 Application of lubricant Position 171 Leveling blade tip 200 Screw feed mechanism E Lubricant allowable supply amount F Cumulative photoreceptor rotation speed G Solid lubricant supply amount H Solid lubricant pressing force J Lubricant R Pressing force Vbr Bias voltage Vo Drum surface potential ΔV Potential difference X Current supply amount of lubricant W Leveling blade wear width θ line Speed ratio

Claims (11)

An image forming apparatus that transfers an image formed on a rotating image carrier to a transfer target and removes a residue on the image carrier after the transfer with a cleaning member,
Application means for applying a lubricant to the image carrier;
A leveling member for leveling the coating thickness of the lubricant applied to the image carrier;
Control means for reducing the amount of lubricant supplied to the image carrier by the coating means based on an increase in the amount of wear of the leveling member in contact with the image carrier via the lubricant;
Equipped with a,
The control means includes
An acquisition means for acquiring an allowable supply amount E of the lubricant to the image carrier;
Supply amount estimating means for estimating a current supply amount X of lubricant to the image carrier by the application means,
The allowable supply amount E is
The relationship with the amount of wear of the leveling member is set in advance so as to decrease as the amount of wear of the leveling member increases.
The control means includes
When the current supply amount X of the lubricant becomes larger than the allowable supply amount E as the wear amount of the leveling member increases, the supply amount of the lubricant to the image carrier is increased from the past. An image forming apparatus characterized by being reduced to a small amount . The application means includes
A rotary conveying member that conveys the lubricant obtained by scraping the solid lubricant to a position where the lubricant is applied to the image carrier;
A pressing member that presses the solid lubricant against the rotary conveying member;
With
The supply amount estimation means includes
Wherein based on the size of the pressing force by the pressing member, an image forming apparatus according to claim 1, wherein the estimating the current supply amount X of the lubricant. The supply amount estimation means includes
The image forming apparatus according to claim 2 , wherein the estimation is performed from information indicating a correspondence relationship between a magnitude of a pressing force by the pressing member and a current supply amount X of the lubricant. The supply amount estimation means includes
The image forming apparatus according to claim 3 , further comprising a detecting unit that detects a magnitude of the pressing force by the pressing member. The detection means includes
The image forming apparatus according to claim 4 , wherein the image forming apparatus is a sensor for detecting a pressing force acting on the rotary conveying member from the solid lubricant. The control means includes
According to any one of claims 1 to 5, characterized in that it comprises a wear amount estimation means for estimating, based on the value indicating the cumulative amount of rotation of said image bearing member to the current wear amount of the leveling member Image forming apparatus. The lubricant has chargeability,
The application means includes
A rotary conveying member that conveys a lubricant from a lubricant supply source to a position where the lubricant is applied to the image carrier;
A potential difference generating means for generating a potential difference between the rotary conveyance member and the image carrier so that an electrostatic force in a direction from the image carrier to the rotary conveyance member acts on the charged lubricant;
With
The control means includes
By changing the occurrence or magnitude of the potential difference, an image forming apparatus according to any one of claims 1 to 6, characterized in that the reduction in the supply amount of the lubricant. The application means includes
A rotary conveying member that conveys the lubricant from the lubricant supply source to the position where the lubricant is applied to the image carrier,
The control means includes
By varying the relative speed difference between the rotary conveyance member and the image bearing member, an image forming according to any one of claims 1 to 7, characterized in that the reduction in the supply amount of the lubricant apparatus. The application means includes
A rotary conveying member that conveys the lubricant obtained by scraping the solid lubricant to a position where the lubricant is applied to the image carrier;
Pressing means for pressing the solid lubricant against the rotary conveying member;
With
The control means includes
By varying the pressing force by the pressing means, the image forming apparatus according to any one of claims 1 to 8, characterized in that the reduction in the supply amount of the lubricant. The control means includes
During the image forming operation for forming an image on the image carrier, the switching of the supply amount of the lubricant to the image carrier by the application unit from the first amount to the second amount smaller than the first amount is switched. not executed in the image forming apparatus according to any one of claims 1 to 9, characterized in that to be executed by the non-image-forming other than during the image forming operation. The leveling member is
An elastic member, an image forming apparatus according to any one of claims 1 to 10, characterized in that is elastically biased to the image bearing member.

Images