JP5505862B2 - Lubricant coating apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a lubricant application device used in an image forming apparatus such as a copying machine, a facsimile machine, a printer, and a multifunction machine of these.

In current image forming apparatuses (particularly color image forming apparatuses using polymerized toner), a lubricant is often applied to the surface of the photosensitive drum for the following reason.
(1) To ensure the cleaning performance of polymerized toner, which is disadvantageous for blade cleaning (cleaning performance can be ensured by lowering the coefficient of friction of the photoreceptor surface)
(2) When the AC voltage (current) is superimposed by the charging means, the surface of the photoreceptor is protected from the AC voltage (current).
In either case, a problem occurs if the specified amount of lubricant is not applied. However, in the case of (1), poor cleaning and filming on the surface of the photoconductor occur. The film pressure of the body drum decreases rapidly, causing a problem that the life is shortened.

However, even when a large amount is applied, the lubricant adheres to the surface of the charging roller, resulting in scumming due to insufficient charging.
As described above, stable application of the lubricant is important. One factor affecting the stability is the linear speed of the photosensitive drum. As an example, in the case of a machine with a linear speed of printing of 600 dpi plain paper: 120 mm / second, and a linear speed of printing of 1200 dpi and thick paper: 60 mm / second, the lubricant consumption amount with respect to the same rotational speed of the photosensitive drum is As shown in graph 1, the result is that the consumption (supply amount) of the lubricant decreases when the photosensitive drum linear velocity is low. In the case of a machine that always prints at a constant speed, the consumption (supply amount) can be determined according to the speed. However, in a machine that uses multiple linear speeds, either linear speed In other words, the lubricant is excessive or insufficient at other linear speeds.

  In addition, as a lubricant, by supplying a solid lubricant with an inorganic lubricant added, lubricity due to electrical stress on the surface of the image carrier due to the charging process can be improved more than when using only a solid lubricant. It has also been reported that the reduction can be suppressed and a high lubricity can be maintained by forming a lubricant film over the entire surface of the image bearing member. However, it has been found that even in such a lubricant, an excess or deficiency of the supply amount occurs due to factors such as linear velocity.

  Patent Document 1 discloses a technique that has a plurality of photosensitive drum linear velocities and changes the filming removal mode in accordance with the linear velocities. However, there is no disclosure about the problem of supplying the lubricant, and there is a problem that it is necessary to care about the charged state in the filming removal mode. That is, there are problems in the stable supply of the lubricant, the stability of the friction coefficient of the photoconductor, and the cleaning properties.

  In view of this, the present invention provides a coating apparatus capable of realizing a stable lubricant coating with respect to a change in linear velocity by changing the supply of the lubricant according to the linear velocity of the rotating photosensitive drum. An object of the present invention is to propose an image forming apparatus.

The lubricant application device of the present invention is
A lubricant application device used for an image forming unit,
The imaging unit is
A rotating photosensitive drum;
Charging means for charging the photoreceptor;
A developing device for forming an image on the surface of the photosensitive drum;
Transfer means for transferring an image formed on the surface of the photosensitive drum ;
A cleaning means for removing residual toner and the photosensitive drum and said transfer means remaining on the photosensitive drum surface or after the direction of rotation of the photosensitive drum from the position and the transfer means abutting
The photosensitive drum has a plurality of linear speeds,
The lubricant application device is
A supply unit that is located between the transfer unit and the cleaning unit , and that constantly supplies a lubricant to the surface of the photosensitive drum when the photosensitive drum rotates;
A lubricant pressed against the supply means;
The lubricant be those obtaining Bei and a pressure means for pressing said feed means,
The lubricant application device comprises:
In addition to the supply unit, the photoconductive drum has a second supply unit for supplying the developing lubricant to the surface of the photoconductive drum,
Feed means said second, at least, the lubricant subjected sheet on the photosensitive drum surface when the linear velocity slowest linear velocity of the photosensitive drum,
The supply means of the second, is the lubricant, using a material obtained by adding inorganic lubricant in the fatty acid metal salt, the supply of or lubricants not matter the state of the presence or absence of charging of the photosensitive drum by the charging means It is characterized by performing.

  The lubricant application apparatus of the present invention is characterized in that the supply of lubricant by the second supply means is performed only before image formation.

  The lubricant application device of the present invention may be characterized in that the supply of the lubricant by the second supply means is performed only after the image formation.

  The lubricant application device of the present invention is characterized in that the supply of the lubricant by the second supply means is performed when the linear velocity of the photosensitive drum is maximum.

  An image forming apparatus according to the present invention includes any one of the above-described lubricant application apparatuses.

  The image forming apparatus of the present invention is characterized in that, when continuous printing is performed, the lubricant is supplied by the second supply unit even between image forming.

  According to the present invention, even when the linear velocity changes, the lubricant can be stably supplied, and the photoreceptor friction coefficient and the cleaning property are also stabilized.

The figure which shows schematic structure of the printer which concerns on the implementation object of this invention The figure which shows one schematic structure of the image station The figure which shows the structure which supplies a lubricant in the rotation direction upstream of a photoconductor with respect to a cleaning position. Schematic diagram for explaining the lubricant supply mechanism in the configuration shown in FIG. Schematic diagram with enlarged lubricant supply section Schematic diagram for explaining the mechanism of lubricant application at high image area The figure which shows the graph which shows the relationship between the number of output sheets, and the friction coefficient on the photoreceptor surface The figure which shows the graph which showed the lubricant consumption per unit number of rotations of a photoconductor for every image station The figure which shows the part of the difference which arises because the consumption of the lubricant per unit revolution number of the photoreceptor differs Diagram showing lubricant supply timing before image formation Schematic diagram showing an example of the second lubricant supply means

The present invention has two lubricant supply means, one of the means always supplies the lubricant, and the other means changes the supply according to the photosensitive drum linear speed, thereby changing the linear speed. A system that can realize stable lubricant application is proposed.
In the present invention, a photosensitive drum that is a rotating image carrier, a charging unit that charges the photosensitive member, a first lubricant supply unit that supplies a lubricant to the surface of the photosensitive drum, and a first lubricant supply An image forming apparatus including a lubricant pressed by the means, a pressing means for pressing the lubricant against the first lubricant supply means, and a second lubricant supply means for supplying the lubricant to the surface of the photosensitive drum. It constitutes a unit.
The first lubricant supply unit is positioned between a position where the transfer unit and the photosensitive drum come into contact with each other and a cleaning unit which removes transfer residual toner remaining on the surface of the photosensitive drum after the transfer. The lubricant is always supplied to the surface of the photosensitive drum when the photosensitive drum rotates. The photosensitive drum rotates at a plurality of linear speeds. The second lubricant supply means supplies the lubricant to the surface of the photosensitive drum at least at the slowest linear velocity separately from the first lubricant supply means. The lubricant to be used is obtained by adding an inorganic lubricant to a fatty acid metal salt, and it does not matter whether the charging means is charged or not when supplied by the first lubricant supplying means. As a result, the small amount of lubricant supplied from the first supply means can be covered by causing the second lubricant supply means to function when the linear rotation speed of the photosensitive drum is low. Therefore, the lubricant can be stably supplied even if the linear rotation speed of the photosensitive drum is changed, and the friction coefficient and cleaning performance of the photosensitive drum are also stabilized.

In the present invention, the supply of lubricant by the second lubricant supply hand stage is to be performed only before imaging, actually at the time of image formation in a slow linear velocity the supply amount of lubricant is reduced, By causing the second lubricant supply means to function before image formation, it is possible to prevent the coating amount from being reduced.

  On the other hand, in the present invention, the supply of the lubricant by the second lubricant supply means can be performed only after the image formation, so that it is possible to avoid giving the user an extra waiting time.

  In the present invention, the lubricant is supplied when the photosensitive drum rotates at the maximum linear speed, thereby reducing the time for applying the lubricant, thereby reducing the waiting time for the user and saving energy. Can be.

  Further, the image forming apparatus equipped with the lubricant application device according to the present invention can stably supply the lubricant even when the linear rotation speed of the photosensitive drum changes, and the photosensitive member friction coefficient and the cleaning property are also stable. Image formation with good image quality can be realized.

  Furthermore, in the image forming apparatus according to the present invention, when continuous printing is performed, the lubricant is supplied by the second lubricant supplying means even during the interval between image formation, and continuous printing (at once) Even when a large number of sheets are printed), the lubricant can be stably supplied. Applying the lubricant between the image formation is because more lubricant is supplied by supplying the lubricant without the transfer residual toner and reverse transfer toner due to the image formation on the photosensitive drum. This is because it can supply (efficiency).

Hereinafter, an embodiment in which the present invention is applied to a full-color printer (hereinafter referred to as “printer”) as an image forming apparatus will be described.
FIG. 1 is a diagram showing a schematic configuration of a printer according to an embodiment of the present invention. As shown in FIG. 1, the printer 100 includes an apparatus main body 1 and a drawer cassette 2 that can store transfer paper P. The printer main body 1 has yellow (Y) and cyan at the center thereof. Image stations 3Y, 3C, 3M, and 3K for forming toner images of each color of (C), magenta (M), and black (K) are provided. In the following, the subscripts Y, C, M, and K of the respective symbols indicate the members for yellow, cyan, magenta, and black, respectively, and the subscripts Y, C, M, and K are omitted for common description thereof. Sometimes.

  FIG. 2 is a diagram showing a schematic configuration of one of the image stations (image station 3Y for Y). The configuration of the image stations 3Y, 3C, 3M, and 3K is the same except that the toner used is different.

  As shown in FIGS. 1 and 2, the image station 3Y is provided with a drum-shaped photoconductor 10Y that is driven to rotate in a direction indicated by an arrow A in FIG. The photoreceptor 10Y is composed of an aluminum cylindrical substrate and an OPC (organic photo semiconductor) photosensitive layer covering the surface of the photoreceptor 10Y. The image station 3Y is a charging device 11Y as a charging unit that uniformly charges the surface of the photoconductor 10Y around the photoconductor 10Y, and a developing unit that develops the electrostatic latent image formed on the photoconductor 10Y with toner. A developing device 12Y, and a cleaning device 13Y as a cleaning unit for cleaning unnecessary toner such as transfer residual toner on the photoreceptor 10Y.

  The charging device 11Y uniformly charges the surface of the photoreceptor 10Y by the action of a charging bias applied to the charging roller 11a by bringing a charging roller 11a as a charging unit close to the surface of the photoreceptor 10Y. . As charging means, there are generally a non-contact type scorotron method and a corotron method, a contact roller charging method using a medium resistance rubber roller, and a non-contact roller charging method. Although the present embodiment is a non-contact roller charging method, other methods may be used. For both the contact roller charging method and the non-contact roller charging method, there are a method of superimposing alternating current on direct current and a method of applying only direct current.

  In the contact roller charging system and the non-contact charging roller system, when alternating current is superimposed on direct current, high image quality can be obtained as compared with direct current, but filming phenomenon of the photoconductor is likely to occur. Further, if AC is controlled at a constant current, there is an advantage that the influence on the photosensitive member charging potential caused by the change in resistance value of the charging roller 11a due to the environmental change can be reduced, but the power supply cost is increased and the sound of the AC high frequency is generated. There may be a problem. On the other hand, when only a direct current is applied, a change in the resistance value of the charging roller due to an environmental change affects the photosensitive member charging potential. In order to reduce this influence, means for correcting the charging bias according to the environmental change Measures such as are necessary.

  Comparing the contact charging roller method with the non-contact charging roller method, the non-contact charging roller method is likely to cause unevenness in the image due to the influence of the gap fluctuation between the surface of the photoreceptor and the charging roller when the alternating current is controlled at a constant current. Therefore, measures such as a means for correcting the charging bias are required to reduce this influence. On the other hand, in the non-contact charging roller system, the charging roller is less likely to get dirty as much as the charging roller is not in contact with the surface of the photoconductor as compared with the contact charging roller system.

  As a means for correcting the charging bias, a means for changing the charging bias by detecting the temperature in the vicinity of the charging roller, a means for changing the charging bias by periodically detecting ground contamination on the photosensitive member, and a feedback current for the charging bias A means for changing the charging bias depending on the value can be used. Further, as a driving method of the charging roller 11a, a method of rotating the charging roller by transmitting the driving force from the photoconductor gear or the like to the charging roller can be employed. In the case of the contact charging roller system, it is also possible to employ a system in which the charging roller 11a is pressed against the surface of the photosensitive member and the charging roller 11a is rotated along with the movement of the surface of the photosensitive member.

  When the surface of the charging roller 11a becomes dirty, the charging ability of the portion where the dirt is attached is reduced, and the photosensitive member cannot be charged to the target potential, and an abnormal image due to defective charging occurs. In order to prevent this, in this embodiment, the charging roller cleaner (cleaning roller) 11b is brought into contact with the surface of the charging roller 11a. As the charging roller cleaner 11b, a flocking roller in which fibers are electrostatically flocked on a metal shaft or a melamine roller in which a melamine resin is arranged around the metal shaft can be used. A melamine roller is often used. When slip occurs between the charging roller cleaner 11b and the charging roller 11a, dirt is rubbed against the surface of the charging roller, and the generation of abnormal images due to the dirt is accelerated. Therefore, the charging roller cleaner 11b is configured to rotate with the charging roller 11a.

  In the developing device 12Y, a developing sleeve 15Y serving as a developer carrying member including a magnetic field generating unit is disposed at a position facing the photoconductor 10Y. Below the developing sleeve 15Y, there are two conveying screws 16a for mixing toner that is replenished from the toner bottle 7Y via a toner replenishing port 17Y via a toner replenishing port 17Y with a developer and circulatingly conveying while stirring. 16b is provided. These conveying screws 16a and 16b convey the developer in opposite directions along the rotation axis, and the developer conveyed to the end by one conveying screw is transferred to the other conveying screw, The developer circulates through the developing device. Then, the developer being conveyed by the second conveying screw 16b is pumped up to the surface of the developing sleeve 15Y. The developer pumped up and carried on the surface of the developing sleeve 15Y is conveyed along with the rotation of the developing sleeve 15Y, and is regulated to a predetermined layer thickness by a doctor blade 14Y as a developer regulating member. It passes through a position (development area) opposite to the. Then, due to the action of the developing bias applied to the developing sleeve 15Y, the toner in the developer moves electrostatically and adheres to the electrostatic latent image on the surface of the photoreceptor in the developing region. As a result, the electrostatic latent image is developed into a toner image. In this embodiment, an example of a two-component development system will be described. However, the present invention is naturally applicable even if a one-component development system development apparatus is used.

  The cleaning device 13Y brings a cleaning blade 13a made of urethane rubber into contact with the surface of the photoconductor from the counter direction with respect to the rotation direction of the photoconductor 10Y, and dams out unnecessary toner and other deposits on the surface of the photoconductor at the edge portion. It is the structure which stops and cleans. As shown in FIG. 2, the cleaning device 13Y includes a recovered toner transport device 130Y that transports the recovered toner recovered from the surface of the photoreceptor 10Y by the cleaning blade 13a. Unnecessary toner or the like blocked by the cleaning blade falls into the cleaning device 13Y, is transported forward or rearward in the drawing by the recovery coil 131Y, and is stored in a waste toner tank. In a color image forming apparatus, there is a problem of color mixing of recovered toner, so that it is generally not reused.

  Below each image station 3Y, 3C, 3M, 3K, there is provided an optical unit 4 as a latent image forming means capable of irradiating the respective photoconductors 10Y, 10C, 10M, 10K with laser light L. Above each of the image stations 3Y, 3C, 3M, and 3K, an intermediate transfer unit 5 as an intermediate transfer unit including an intermediate transfer belt 20 as an intermediate transfer body onto which a toner image formed by each image station is transferred. I have. The intermediate transfer belt 20 is made of a heat resistant material such as polyimide or polyamide.

  The image forming apparatus also includes a fixing device 6 as a fixing unit that fixes the toner image transferred to the intermediate transfer belt 20 to the transfer paper P. The fixing device 6 performs fixing by heat and pressure with the transfer paper P sandwiched between a heating roller having a halogen heater inside and a pressure roller.

  In addition, toner bottles 7Y, 7C, and 7M serving as toner containers that store replenishment toners of each color of yellow (Y), cyan (C), magenta (M), and black (K) are disposed on the upper portion of the apparatus main body 1. , 7K are arranged. The toner bottles 7 </ b> Y, 7 </ b> C, 7 </ b> M, and 7 </ b> K are configured to be detachable from the apparatus main body 1 by opening a paper discharge tray 8 formed on the upper part of the apparatus main body 1.

  The optical unit 4 reflects a laser beam L emitted from a laser driving unit including a laser diode as a light source by a polygon mirror or the like, and sequentially scans the photosensitive members 10Y, 10C, 10M, and 10K while irradiating them. . The intermediate transfer belt 20 of the intermediate transfer unit 5 is stretched around a driving roller 21, a tension roller 22 and a driven roller 23, and is driven to rotate counterclockwise in the drawing at a predetermined timing. Further, the intermediate transfer unit 5 includes primary transfer rollers 24Y, 24C, 24M, and 24K as transfer members that transfer the color toner images formed on the photoreceptors 10Y, 10C, 10M, and 10K to the intermediate transfer belt 20. Yes. The intermediate transfer unit 5 includes a secondary transfer roller 25 that transfers the toner image transferred onto the intermediate transfer belt 20 to the transfer paper P, residual toner on the intermediate transfer belt 20 that has not been transferred onto the transfer paper P, and the like. A belt cleaning device 26 for cleaning is also provided.

Next, an image forming operation when forming a color image in the printer 100 will be described.
First, in each of the image stations 3Y, 3C, 3M, and 3K, the surfaces of the photoconductors 10Y, 10C, 10M, and 10K that are rotationally driven by a driving source (not shown) are the charging rollers 11a of the charging devices 11Y, 11C, 11M, and 11K. Are uniformly charged. Thereafter, the optical unit 4 scans and exposes the laser light L based on the image information of each color, and electrostatic latent images corresponding to the respective colors are formed on the surfaces of the photoreceptors 10Y, 10C, 10M, and 10K. The electrostatic latent images on the photoconductors 10Y, 10C, 10M, and 10K are developed by the toners of the respective colors carried on the developing sleeves 15 of the developing devices 12Y, 12C, 12M, and 12K, and are visible as toner images. It becomes. The toner images formed on the photoreceptors 10Y, 10C, 10M, and 10K in this way are rotationally driven counterclockwise by the action of the primary transfer bias applied to each primary transfer roller 24Y, 24C, 24M, and 24K. The images are sequentially electrostatically transferred so as to overlap each other on the intermediate transfer belt 20. The photoreceptors 10Y, 10C, 10M, and 10K after the completion of the primary transfer are unnecessary toners that adhere to the surfaces of the photoreceptors at portions where the cleaning blades 13a that are cleaning members of the cleaning devices 13Y, 13C, 13M, and 13K come into contact, respectively. Is cleaned by damming with a cleaning blade 13a.

  The transfer paper P in the paper feed cassette 2 is conveyed into the apparatus main body 1 by a paper feed roller 27 disposed in the vicinity of the paper feed cassette 2, and is transferred to the secondary transfer section at a predetermined timing by a registration roller pair 28. Be transported. Then, the superimposed toner image formed on the intermediate transfer belt 20 is transferred onto the transfer paper P in the secondary transfer portion. The transfer paper P onto which the superimposed toner image has been transferred passes through the fixing device 6 to be fixed, and is discharged to the paper discharge tray 8 by the discharge roller 29. Transfer residual toner or the like remaining on the intermediate transfer belt 20 is cleaned by a belt cleaning device 26 that performs contact cleaning on the intermediate transfer belt 20.

  The replenishment toner filled in the toner bottles 7Y, 7C, 7M, and 7K passes through the toner conveyance path by a toner replenishing device (not shown) as necessary, at each replenishment timing, at each replenishment timing. A predetermined amount is supplied to the developing devices 12Y, 12C, 12M, and 12K of 3Y, 3C, 3M, and 3K. The order of arrangement of the four image stations 3Y, 3C, 3M, and 3K and the toner bottles 7Y, 7C, 7M, and 7K is not limited to the example shown in FIG.

  In addition, as shown in FIG. 2, the surface of the photoconductor 10Y has a powder on the downstream side in the rotation direction of the photoconductor 10Y with respect to the position where the cleaning blade 13a contacts the photoconductor 10Y (hereinafter referred to as “cleaning position”). A lubricant application device 140Y is arranged as a first lubricant supply means for supplying a body-like lubricant. The lubricant application device 140Y includes a solid lubricant 141Y and an application brush roller 142Y. The application brush roller 142Y that contacts the photoconductor 10Y and the lubricant application device 140Y while rotating scrapes off the lubricant application device 140Y. The lubricant is applied to the photoconductor 10Y. The lubricant applied to the surface of the photoreceptor is leveled to a uniform thickness by a lubricant leveling blade 143Y as a lubricant leveling means and fixed on the surface of the photoreceptor.

  The lubricant is mainly for lowering the coefficient of friction between the surface of the photoreceptor and the contact object such as toner and cleaning blade in contact therewith. By reducing the friction coefficient, it is possible to suppress the occurrence of a filming phenomenon on the surface of the photoreceptor and to improve the cleaning property. The lubricant also functions to suppress deterioration of the surface of the photoreceptor due to a charging bias including alternating current.

  The most commonly used lubricant is ZnSt (zinc stearate), but the present invention is preferably a fatty acid metal salt, that is, a metal soap to which an inorganic lubricant is added. In addition, as a material of the application brush roller 142Y, insulating PET (Polyethylene Terephthalate), conductive PET, acrylic fiber, or the like can be used. Among these, it is preferable to use a conductive brush in order to avoid an abnormal image due to the effect of frictional charging between the application brush roller 142Y and the surface of the photoreceptor. Further, as means for pressing the solid lubricant 141Y toward the application brush roller 142Y, means such as pressing by a compression spring, pressing by a weight, pressing by a tension spring and a cam, etc. are known. It is most often used because of its balance of function, space and cost.

  The image station shown in FIG. 2 is configured to supply the lubricant on the downstream side in the rotation direction of the photoconductor 10Y with respect to the cleaning position, but as shown in FIG. 3, the rotation of the photoconductor 10Y with respect to the cleaning position. The configuration may be such that the lubricant is supplied on the upstream side in the direction. In this case, the cleaning blade 13a also functions as a lubricant leveling means for thinly stretching and leveling the powdery lubricant applied on the surface of the photoreceptor. When a lubricant is applied to the surface of the photoconductor, if an adherent such as toner adheres to the surface of the photoconductor, the amount of lubricant applied to the part where the adhering material is attached is obstructed by the adhering matter. This is less than the amount of lubricant applied to the portion where the kimono is not attached. Therefore, the configuration shown in FIG. 2 is preferable from the viewpoint of stabilizing the lubricant application amount. On the other hand, since the cleaning blade 13a can be used as the lubricant leveling means, the configuration shown in FIG. 3 is lower in cost than the configuration shown in FIG. 2 in which the lubricant leveling blade 143Y is separately provided. There are advantages.

  In the image station 3Y, the photosensitive member 10Y and at least one of the charging device 11Y, the developing device 12Y, the cleaning device 13Y, and the lubricant applying device 140Y are integrally supported, and a process cartridge that is detachable from the apparatus main body 1 is mounted. It is composed. The other three image stations 3C, 3M, and 3K have the same configuration and are detachable from the apparatus main body 1 as process cartridges.

  The printer 100 of the present embodiment is a so-called tandem color image forming apparatus, and the transfer system is an intermediate transfer system using an intermediate transfer body, but is not limited to this, and each of the photoconductors 10Y, 10C, 10M, A direct transfer method in which the toner image is directly transferred from 10K to the transfer paper P may be used. Of course, a color image forming apparatus other than the tandem type or a monochrome image forming apparatus may be used.

Next, the mechanism for supplying the lubricant to the surface of the photoreceptor will be outlined.
4 is a schematic diagram for explaining the lubricant supply mechanism in the configuration shown in FIG. 3, and FIG. 5 is an enlarged schematic diagram of the lubricant supply unit. The illustrated example is for the black image station 3K, and this will be described as an example. The following description is an example of the intermediate transfer method, but the same applies to the direct transfer method, and the same applies to the image stations 3C and 3M in which the image station exists on the upstream side.

  The black image station 3K is located downstream of the other image stations 3Y, 3C, 3M in the surface movement direction of the intermediate transfer belt 20. Therefore, at the time of color image formation, the surface portion of the intermediate transfer belt 20 entering the primary transfer portion (nip) formed between the photoconductor 10K of the black image station 3Y and the primary transfer roller 24K has other The toner images TYCM transferred at the image stations 3Y, 3C, and 3M are attached. A black toner image TK is formed on the surface of the photoconductor 10K of the black image station 3Y so as to overlap with the toner image TYCM, and the toner image TK overlaps with the toner image TYCM at the primary transfer portion. Are transferred onto the intermediate transfer belt 20.

  During this transfer, a part of the toner image TYCM that has already been transferred onto the intermediate transfer belt 20 is reversely transferred onto the surface of the photoreceptor 10K of the black image station 3K by an electric force. On the other hand, not all of the toner image TK on the photoreceptor 10K is transferred to the intermediate transfer belt 20, and a part of the toner image TK passes through the primary transfer portion. Therefore, the surface portion of the photoconductor 10K on the downstream side in the movement direction of the photoconductor surface of the primary transfer portion is a state where unnecessary toner T′YCMK in which the transfer residual toner of the toner image TK and the reverse transfer toner of the toner image TYCM are mixed adheres It has become.

  In the configuration shown in FIG. 3, since the lubricant is applied to the surface of the photosensitive member before cleaning, the lubricant is applied to the surface of the photosensitive member to which unnecessary toner T′YCMK is attached. The application brush roller 142K holds the powdered lubricant J1 scraped from the solid lubricant 141K on the brush portion, and brings the brush portion into contact with the surface of the photoconductor, whereby the powdery lubricant J1 is transferred to the photoconductor. Supply to the surface. At this time, the application brush roller 142K collects a part of the unnecessary toner T′YCMK present on the surface of the photoreceptor. On the other hand, a part of the powdery lubricant J1 scraped off from the solid lubricant 141K leaves the contact portion (lubricant supply portion) between the application brush roller 142K and the surface of the photoreceptor adhered to the application brush roller 142K. pass. In the present embodiment, a flicker 143K is provided to collect unnecessary toner T′YCMK adhering to the application brush roller 142K from the brush. The flicker 143K is often formed integrally with a frame (not shown) or a metal shaft is used, and a PET sheet is often used. Which one is selected is selected according to conditions such as the thickness, density, installation space, and the like of the hair of the application brush roller 142K. The flicker 143K causes the unnecessary toner T′YCMK to fall from the application brush roller 142K, but also removes the lubricant J1 that has passed through the lubricant supply unit. As a result, the solid lubricant 141K can always be brought into contact with the brush portion to which the lubricant is not so much adhered, and the amount of lubricant scraped from the solid lubricant 141K can be stabilized.

  The powdery lubricant J1 supplied to the surface of the photoreceptor is still weak in adhesion to the surface of the photoreceptor immediately after being supplied, but is dammed up at the edge of the cleaning blade 13a, thereby gradually thinning the layer. And becomes a finer powdery lubricant J2, passing through the blade edge. During this passage, the lubricant is strongly pressed against the surface of the photoconductor, and the adhesion with the surface of the photoconductor is increased and fixing is performed. The lubricant J2 fixed on the surface of the photoreceptor is gradually destroyed by being exposed to an alternating charging bias or subjected to stress at the developing portion, and the new lubricant J1 is applied from the application brush roller 142K. Is replenished. The particle size of the powdery lubricant J1 is about several tens of μm to several hundreds of μm, which is larger than the particle size of the toner in this embodiment.

  FIG. 6 is a schematic diagram for explaining a lubricant application mechanism when the image area is high. As shown in FIG. 3, when the lubricant is supplied on the upstream side in the moving direction of the photoconductor surface from the cleaning position, it becomes difficult to supply the lubricant to the photoconductor surface when forming an image with a large image area. There is a disadvantage that the amount of the agent supplied is reduced. This is because the amount of the unnecessary toner T′YCMK that is input to the lubricant supply unit at the time of forming an image with a large image area increases, and the unnecessary toner T′YCMK prevents the lubricant from adhering to the surface of the photoreceptor. This is because the amount increases. Therefore, when an image with a large image area is formed, problems such as poor cleaning, filming phenomenon, and blade squealing are liable to occur. Therefore, for example, if the lubricant supply amount is set to be large so that the lubricant supply amount is not insufficient even when the image area is high, the lubricant supply amount is excessive when the image area is low. If the lubricant supply amount is excessive, for example, the charging roller 11a of the charging device may be excessively contaminated with the lubricant, which may cause charging failure. In a high humidity environment, a large amount of lubricant on the surface of the photoconductor absorbs moisture and becomes conductive, disturbing the electrostatic latent image on the surface of the photoconductor and causing image degradation such as image flow or image blurring. There is also a fear. On the contrary, for example, if the lubricant supply amount is set to be small so that the lubricant supply amount does not become excessive even when the image area is low, the lubricant supply amount is insufficient when the image area is high. It is easy to cause problems such as phenomenon and blade noise.

  FIG. 7 shows a case where the image area ratio is 5%, which is an image area ratio when a standard character image is printed, and a case where the image area ratio is about 25%, which is a high image area ratio, such as when a photographic image is printed. 6 is a graph showing the relationship between the number of output sheets and the coefficient of friction on the surface of the photoreceptor. As is clear from this graph, when the image area ratio is 5%, that is, when the image area is low and high, the friction coefficient on the surface of the photoreceptor is gradually increased by repeating the output, but it is so large. It can be seen that the effect of the lubricant is stably exhibited without increasing. On the other hand, when the image area ratio is about 25%, that is, in the case of a high image area, the friction coefficient on the surface of the photoconductor suddenly increases due to repeated output, and the effect of the lubricant is not immediately exerted. It has become. This is because the supply amount of the lubricant is small because it is obstructed by unnecessary toner as described above.

  FIG. 8 shows the lubricant consumption per unit rotation number for each image station when the linear velocity (surface moving speed) of the photoconductor is 120 [mm / sec] and 60 [mm / sec]. It is the shown graph. The photosensitive member is driven at a linear speed of 120 [mm / sec] when an image is formed on plain paper at 600 dpi. On the other hand, the photosensitive member is driven at a linear speed of 60 [mm / sec] when forming an image on plain paper at 1200 dpi or when forming an image on thick paper. As can be seen from the graph shown in FIG. 8, the amount of lubricant consumed per unit rotational speed of the photoconductor is as shown in graph 2, and decreases as the photoconductor linear speed decreases. Therefore, the lower the photosensitive member linear velocity, the smaller the lubricant supply amount per unit area supplied to the surface of the photosensitive member. Therefore, if the image forming operation is repeated by driving the photosensitive member at a slow linear speed, the coefficient of friction on the surface of the photosensitive member increases and the effect of the lubricant is not exhibited. It tends to cause problems such as mingling and blade noise.

  Therefore, in the configuration in which the image forming is performed by switching the linear speed of the photosensitive member in this way, for example, when the lubricant supply amount is set to be large so that the lubricant supply amount is not insufficient even when the photosensitive member is driven at a slow linear speed. When the photosensitive member is driven at a high linear velocity, the lubricant supply amount becomes excessive. If the lubricant supply amount is excessive, for example, the charging roller 11a of the charging device may be excessively contaminated with the lubricant, which may cause charging failure. In a high humidity environment, a large amount of lubricant on the surface of the photoconductor absorbs moisture and becomes conductive, disturbing the electrostatic latent image on the surface of the photoconductor and causing image degradation such as image flow or image blurring. There is also a fear. On the contrary, for example, if the lubricant supply amount is set to be small so that the lubricant supply amount does not become excessive even when the photosensitive member is driven at a high linear velocity, the lubricant supply amount when the photosensitive member is driven at a low linear velocity. As described above, it tends to cause problems such as poor cleaning, filming phenomenon, and blade squealing.

  Therefore, in this embodiment, even when the amount of lubricant supplied to the surface of the photoconductor 10 changes as described above, the change in the amount of lubricant adhering to the surface of the photoconductor due to this change is reduced, so that the surface of the photoconductor A configuration that suppresses the occurrence of problems due to insufficient or excessive lubricant adhesion is adopted. That is, the second lubricant supply means is made to function before the cleaning blade 13a with respect to the photoconductor.

  Specifically, apart from the application brush roller 142K and the solid lubricant 141K which are the first lubricant supply means described above, the second lubricant is supplied to the surface of the photoconductor 10 at least at the slowest linear velocity. Lubricant supply means is arranged. Although illustration is omitted, the second lubricant supply means may have the same configuration as the first lubricant supply means. For example, a bottle containing a lubricant may be provided as the supply means. However, as the lubricant to be used, it is assumed that an inorganic lubricant is added to the fatty acid metal salt, and it does not matter whether the charging means is charged or not during supply.

  Then, an ideal amount of lubricant consumption is input in advance to the control device of the printer 100, for example, and a portion that is less than the ideal amount is supplied from the second lubricant supply means to the photoconductor 10 before image formation. To do.

  For example, when the image forming apparatus has two linear speeds of 120 mm / second and 60 mm / second, and the ideal lubricant consumption is the consumption when the paper is passed at 120 mm / second. explain. As shown in FIG. 9, at two linear speeds of 120 mm / second and 60 mm / second, the amount of lubricant consumed per unit revolution of the photoconductor 10 is different. The amount of lubricant corresponding to the hatched portion indicated by D) is supplied by the second supply means before image formation.

  That is, the cumulative number of rotations of the photoconductor 10 at 60 mm / second is recorded between this previous operation and the current operation, and the amount of lubricant that is insufficient per unit rotation number of the photoconductor 10 (see FIG. The amount of lubricant required is calculated by multiplying the amount corresponding to the portion of the reference symbol D), and a sufficient time for supplying the amount of lubricant, for example, a bottle containing lubricant (second lubricant supply means) ) Is rotated.

  Then, as shown in FIG. 10, it is performed at the maximum linear velocity (120 mm / second in this example) only when the lubricant is supplied before image formation (the supply time is the first 10 hours in the figure), and thereafter the line during image formation is obtained. Control that operates at a high speed (60 mm / sec in this example) can be performed. Note that the lubricant supply from the second lubricant supply means is performed only after image formation in the above description, but may be performed only during image formation. The concept of supplying the lubricant from the second lubricant supply means is the same as that performed only after image formation.

  FIG. 11 is a schematic diagram illustrating an example of a second lubricant supply unit. The second lubricant supply means in this example uses a toner replenishing device 70K as a toner replenishing means to develop the lubricant that is previously stored in a powder state in the lubricant bottle 9K that is a lubricant container. Then, the lubricant is supplied to the surface of the photoreceptor 10K together with the toner by the developing device 12K. Here, the configuration of the black image station 3K will be described as an example, but the same applies to the multicolor image stations 3Y, 3C, and 3M.

  In this example, the toner concentration in the developer in the developing device 12K is detected by a toner concentration sensor (not shown), and toner is supplied to the developing device 12K according to the detection result. The toner bottle 7K containing the replenishing toner is a general screw bottle, and the toner in the bottle can be conveyed in the direction perpendicular to the paper surface by rotating in the direction of the arrow in the figure. Toner is discharged from the bottle discharge port provided. The toner discharged from the toner bottle 7K falls into the toner conveyance path 72K of the toner replenishing device 70K, and is conveyed in the toner conveyance path 72K diagonally upward to the right in the drawing by the replenishing screw 71K that conveys the toner in the rotation axis direction. Is done. The toner transport path 72K of the transport destination is provided with a drop hole communicating with the toner replenishing port 17K of the developing device 12K, and the toner conveyed by the replenishing screw 71K passes through the toner replenishment port 17K through the drop hole. It is supplied into the developing device 12K.

  On the other hand, the configuration of the lubricant supply to the developing device 12K will be described. The lubricant bottle 9K is also a general screw bottle like the toner bottle. Therefore, when the lubricant bottle 9K rotates in the direction of the arrow in the figure, the powdery lubricant in the bottle can be transported in the direction perpendicular to the paper surface, and the lubricant is discharged from the bottle discharge port provided at the transport destination. Is discharged. Since the lubricant discharged from the lubricant bottle 9K falls from above the dropping hole in the toner transport path 72K of the toner replenishing device 70K, the lubricant inside the developing device 12K passes through the dropping hole via the toner replenishing port 17K. To be supplied. Therefore, in the present configuration example 1, the lubricant supply to the surface of the photosensitive member via the developing device 12K can be controlled by controlling the rotational driving of the lubricant bottle 9K.

  The toner and the lubricant that have dropped into the developing device 12K are conveyed while being agitated with the developer by the first conveying screw 16a, and are delivered to the second conveying screw 16b side. Then, during the conveyance of the second conveying screw 16b, it is pumped up together with the developer to the developing sleeve 15K and supplied to the surface of the photoreceptor 10K in the developing region.

  In this example, on the basis of the above-described concept of supplying the lubricant, the rotational drive of the lubricant bottle 9K is ON / OFF controlled to control the timing of supplying the lubricant from the lubricant bottle 9K. The steady supply of the lubricant by the coating device 140K compensates for the shortage when the lubricant supply amount is insufficient.

  The configuration of the second lubricant supply means can be variously employed other than those described above, and is not limited to the illustrated one. Also, as the supply timing control means, various known means and devices can be adopted, and the description thereof is omitted.

DESCRIPTION OF SYMBOLS 1 Printer apparatus body 2 Paper feed cassette 3 Image station 4 Optical unit 5 Intermediate transfer unit 7 Toner bottle 9 Lubricant bottle 10 Photoconductor 11 Charging device 12 Developing device 13 Cleaning device 13a Cleaning blade 20 Intermediate transfer belt 24 Primary transfer roller 40 Image memory unit 41 Laser drive unit 42 Latent image dot count unit 43 Image dot number calculation unit 44 Control unit 45 Lubricant bottle rotation drive unit 46 Photoconductor drive torque detection unit 70 Toner supply device 71 Supply screw 72 Toner conveyance path 73 Sub hopper 74 Stir paddle 100 Printer 140 Lubricant application device 141 Solid lubricant 142 Application brush roller 150 Second lubricant application device 151 Case 152 Application brush roller 153 Application blade 250 Lubricant supply device P Transfer paper D Difference in lubricant consumption

JP 2006-154212 A

Claims (6)

A lubricant application device used for an image forming unit,
The imaging unit is
A rotating photosensitive drum;
Charging means for charging the photoreceptor;
A developing device for forming an image on the surface of the photosensitive drum;
Transfer means for transferring an image formed on the surface of the photosensitive drum ;
A cleaning means for removing residual toner and the photosensitive drum and said transfer means remaining on the photosensitive drum surface or after the direction of rotation of the photosensitive drum from the position and the transfer means abutting
The photosensitive drum has a plurality of linear speeds,
The lubricant application device is
A supply unit that is located between the transfer unit and the cleaning unit , and that constantly supplies a lubricant to the surface of the photosensitive drum when the photosensitive drum rotates;
A lubricant pressed against the supply means;
E Bei and a pressure means for pressing the lubricant to the supply means
And
The lubricant application device comprises:
In addition to the supply unit, the photoconductive drum has a second supply unit for supplying the developing lubricant to the surface of the photoconductive drum,
Feed means said second, at least, the lubricant subjected sheet on the photosensitive drum surface when the linear velocity slowest linear velocity of the photosensitive drum,
The supply means of the second, is the lubricant, using a material obtained by adding inorganic lubricant in the fatty acid metal salt, the supply of or lubricants not matter the state of the presence or absence of charging of the photosensitive drum by the charging means A lubricant application device characterized in that:
The lubricant application device according to claim 1, wherein
The lubricant application apparatus according to claim 1, wherein the lubricant is supplied by the second supply means only before image formation. The lubricant application device according to claim 1, wherein
The lubricant application apparatus according to claim 2, wherein the lubricant is supplied by the second supply means only after image formation. In the lubricant application device according to any one of claims 1 to 3,
The lubricant application by the second supply means is performed when the linear velocity of the photosensitive drum is the highest.   An image forming apparatus comprising the lubricant application device according to claim 1. The image forming apparatus according to claim 5.
An image forming apparatus characterized in that, when continuous printing is performed, the lubricant is supplied by the second supply means even between image forming.