JP2017003680A - Image forming apparatus, image forming system, and lubricant adjustment control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can prevent a reduction in the amount of lubricant on an image carrier to prevent the occurrence of image defects without causing an increase in size and complexity in control of the apparatus, an image forming system, and a lubricant adjustment control method.SOLUTION: An image forming apparatus comprises: an image carrier; and a lubricant storage part that stores a first lubricant that exhibits the same behavior as that of a toner in a development field for developing an electrostatic latent image formed on the image carrier with the toner, and a second lubricant that exhibits a different behavior from that of the toner.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an image forming apparatus, an image forming system, and a lubricant adjustment control method.

  In an electrophotographic image forming apparatus, as a means for removing residual toner such as untransferred toner and transfer residual toner on an image carrier (for example, a photoreceptor), for example, a cleaning blade is provided on the surface of the image carrier. There is known a blade cleaning type cleaning device that abuts to remove residual toner on an image carrier.

  In recent years, there has been a demand for a smaller particle size of toner particles from the viewpoint of high image quality. As a method for obtaining such toner particles, for example, a polymerization method such as an emulsion polymerization method or a suspension polymerization method is used. However, since the adhesion between the toner particles and the image carrier increases as the particle size of the toner particles decreases, it becomes difficult to remove the residual toner on the image carrier. In particular, when a so-called polymerized toner produced by a polymerization method is used, the toner particles have a shape close to a sphere, so that a cleaning failure occurs in which the toner particles roll on the image carrier and pass through the cleaning blade. Eventually, image defects such as FD streaks (streaks in the rotation direction of the image carrier) occur.

  In order to cope with such poor cleaning, at present, a lubricant external additive (lubricant) is supplied onto the image carrier to form a lubricant film, thereby reducing the adhesion between the toner particles and the image carrier. Cleaning is being performed. As a method for supplying the lubricant onto the image carrier, for example, a toner external addition method in which a toner image is formed with a toner to which a lubricant is added and the lubricant is supplied.

  However, in the toner external addition system, the amount of lubricant in the developing device varies depending on the amount of toner consumed, and as a result, the amount of lubricant coated on the image carrier varies. For example, if an image with a low printing rate is continuously printed, only the lubricant released from the toner is preferentially consumed in the background portion (non-image portion), and no new toner (lubricant) is supplied to the developing device. Therefore, finally, supply and discharge are balanced and stabilized in a state where the amount of lubricant in the developing device is reduced. The lubricant on the image carrier can be maintained at a certain level because only the lubricant is supplied at first. However, when the amount of lubricant in the developing device gradually decreases, the amount of lubricant supplied to the surface of the image carrier and thus the coverage decreases, and the adhesion between the toner particles and the image carrier cannot be reduced, resulting in poor cleaning. Leads to the occurrence of In addition, when the amount of lubricant coated on the image carrier varies, there are portions on the image carrier with a large amount of lubricant and a portion with a small amount of lubricant. (Potential) becomes non-uniform and an image density step (image defect) occurs.

  In order to solve the above problem, Patent Documents 1 and 2 disclose that an image carrier is provided with means for supplying a lubricant onto the image carrier by forming a toner image on the image carrier using a toner to which a lubricant is added. The thing provided with the lubricant application means which apply | coats a lubricant on the top is disclosed. In the technique described in Patent Document 1, when an image having a low printing rate is continuously printed, that is, when the amount of lubricant supplied on the image carrier by the formation of the toner image is small, the image on the image carrier by the lubricant application unit is used. By increasing the amount of lubricant applied to the surface, the amount of lubricant on the image carrier is prevented from decreasing. On the other hand, in the technique described in Patent Document 2, when an image having a low printing rate is continuously printed, that is, when the amount of lubricant applied to the image carrier by the lubricant coating device is small, the image carrier is formed by forming a toner image. By increasing the amount of lubricant supplied above, the amount of lubricant on the image carrier is prevented from decreasing.

JP 2003-149995 A JP 2011-28202 A

  However, in the techniques described in Patent Documents 1 and 2, since it is necessary to provide a lubricant application means in addition to a means for supplying a lubricant on the image carrier by forming a toner image, the size of the apparatus is increased. There was a problem that the control was complicated.

  An object of the present invention is to provide an image forming apparatus and an image forming apparatus capable of preventing the occurrence of image defects by preventing a decrease in the amount of lubricant on the image bearing member without increasing the size of the apparatus or complicating the control. A system and lubricant adjustment method is provided.

An image forming apparatus according to the present invention includes:
An image carrier;
A first lubricant that exhibits the same behavior as the toner with respect to a developing electric field for developing the electrostatic latent image formed on the image carrier with toner, and a second lubricant that exhibits a behavior different from that of the toner are contained. A lubricant containing part,
Is provided.

An image forming system according to the present invention includes:
An image forming system including a plurality of units including an image forming apparatus,
An image carrier;
A first lubricant that exhibits the same behavior as the toner with respect to a developing electric field for developing the electrostatic latent image formed on the image carrier with toner, and a second lubricant that exhibits a behavior different from that of the toner are contained. A lubricant containing part,
Is provided.

The lubricant adjustment control method according to the present invention,
A lubricant containing portion containing a first lubricant exhibiting the same behavior as the toner with respect to a developing electric field for developing the electrostatic latent image formed on the image bearing member with toner, and a second lubricant exhibiting a behavior different from that of the toner. Housed in
Based on image formation information relating to image formation, the weights of the first and second lubricants in the lubricant container are adjusted.

  According to the present invention, it is possible to prevent the occurrence of image defects by preventing a decrease in the amount of lubricant on the image carrier without increasing the size of the apparatus or complicating the control.

1 is a diagram schematically showing the overall structure of an image forming apparatus in the present embodiment. FIG. 2 is a diagram illustrating a main part of a control system of the image forming apparatus according to the present embodiment. It is a figure which shows the specific structure of the developing device in this Embodiment. FIG. 4A is a diagram illustrating the developer immediately after being supplied from the developer hopper to the developing device, and FIG. 4B is a diagram illustrating the developer after being stirred in the developing device. It is explanatory drawing explaining the behavior of a 1st and 2nd lubricant. It is a flowchart which shows the lubricant adjustment operation | movement in this Embodiment. FIG. 3 is a diagram schematically illustrating a toner image forming area and a lubricant discharge area disposed on the surface of the photosensitive drum. It is a figure which shows the modification of the concrete structure of the developing device in this Embodiment. It is a flowchart which shows the modification of the lubricant adjustment operation | movement in this Embodiment.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings. FIG. 1 is a diagram schematically showing an overall configuration of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 shows a main part of the control system of the image forming apparatus 1 according to the present embodiment. An image forming apparatus 1 shown in FIGS. 1 and 2 is an intermediate transfer type color image forming apparatus using electrophotographic process technology. In other words, the image forming apparatus 1 has each color of Y (yellow), M (magenta), C (cyan), and K (black) formed on the photosensitive drum 413 (corresponding to the “image carrier” of the present invention). The toner image is transferred (primary transfer) to the intermediate transfer belt 421, and the four color toner images are superimposed on the intermediate transfer belt 421, and then transferred to the paper S (secondary transfer) to form an image.

  Further, in the image forming apparatus 1, the photosensitive drums 413 corresponding to the four colors of YMCK are arranged in series in the running direction of the intermediate transfer belt 421, and the respective color toner images are sequentially transferred to the intermediate transfer belt 421 in one step. Tandem system is adopted.

  As shown in FIG. 2, the image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40 (corresponding to the “adjusting unit” of the present invention), a sheet conveying unit 50, a fixing unit. Unit 60 and control unit 100.

  The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. The CPU 101 reads a program corresponding to the processing content from the ROM 102 and develops it in the RAM 103, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the developed program. At this time, various data stored in the storage unit 72 is referred to. The storage unit 72 includes, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive. In the present embodiment, the storage unit 72 stores image formation information related to a print job (image formation process) executed by the image forming unit 40. The image formation information includes, for example, information such as the number of printed sheets and the input image printing rate.

  The control unit 100 transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 71. . For example, the control unit 100 receives input image data transmitted from an external device, and forms an image on the paper S based on the input image data. The communication unit 71 is composed of a communication control card such as a LAN card, for example.

  The image reading unit 10 includes an automatic document feeder 11 called an ADF (Auto Document Feeder), a document image scanning device 12 (scanner), and the like.

  The automatic document feeder 11 transports the document D placed on the document tray by a transport mechanism and sends it out to the document image scanning device 12. The automatic document feeder 11 can continuously read images (including both sides) of a large number of documents D placed on the document tray all at once.

  The document image scanning device 12 optically scans a document conveyed on the contact glass from the automatic document feeder 11 or a document placed on the contact glass, and reflects light from the document to a CCD (Charge Coupled Device). ) An image is formed on the light receiving surface of the sensor 12a, and an original image is read. The image reading unit 10 generates input image data based on the reading result by the document image scanning device 12. The input image data is subjected to predetermined image processing in the image processing unit 30.

  The operation display unit 20 is configured by, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, image states, operation states of functions, and the like according to a display control signal input from the control unit 100. The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs an operation signal to the control unit 100.

  The image processing unit 30 includes a circuit that performs digital image processing on input image data according to initial settings or user settings. For example, the image processing unit 30 performs gradation correction based on the gradation correction data (gradation correction table) under the control of the control unit 100. Further, the image processing unit 30 performs various correction processes such as color correction and shading correction, a compression process, and the like on the input image data in addition to the gradation correction. The image forming unit 40 is controlled based on the image data subjected to these processes.

  The image forming unit 40 is based on the input image data, and image forming units 41Y, 41M, 41C, 41K, and an intermediate transfer unit 42 for forming an image using colored toners of Y component, M component, C component, and K component. Etc.

  The Y component, M component, C component, and K component image forming units 41Y, 41M, 41C, and 41K have the same configuration. For convenience of illustration and explanation, common constituent elements are denoted by the same reference numerals, and in order to distinguish them, Y, M, C, or K is added to the reference numerals. In FIG. 1, only the components of the Y-component image forming unit 41Y are denoted by reference numerals, and the constituent elements of the other image forming units 41M, 41C, and 41K are omitted.

  The image forming unit 41 includes an exposure device 411, a developing device 412 (corresponding to the “lubricant storage unit” of the present invention), a photosensitive drum 413, a charging device 414, a drum cleaning device 415, a charge amount adjusting unit 416, and the like.

  The photoreceptor drum 413 is made of an organic photoreceptor in which a photosensitive layer made of a resin containing an organic photoconductor is formed on the outer peripheral surface of a drum-shaped metal substrate, for example. Examples of the resin constituting the photosensitive layer include polycarbonate resin, silicone resin, polystyrene resin, acrylic resin, methacrylic resin, epoxy resin, polyurethane receiver, vinyl chloride resin, and melamine resin.

  The control unit 100 controls a drive current supplied to a drive motor (not shown) that rotates the photosensitive drum 413, so that the photosensitive drum 413 rotates at a constant peripheral speed.

  The charging device 414 is, for example, a charging charger, and uniformly charges the surface of the photoconductive drum 413 with negative polarity (for example, −500 [V]: background portion) by generating corona discharge. Let

  The exposure device 411 is composed of, for example, a semiconductor laser, and irradiates the photosensitive drum 413 with laser light corresponding to the image of each color component. As a result, an image portion (for example, −50 [V]) irradiated with laser light on the surface of the photosensitive drum 413 has a static potential of each color component due to a potential difference (for example, −450 [V]) from the background portion. An electrostatic latent image is formed.

  The developing device 412 is a two-component reversal developing device, and develops (visualizes) the electrostatic latent image by attaching toner of each color component to the surface of the photosensitive drum 413 to form a toner image. Specifically, the developing device 412 includes a developing sleeve disposed so as to face the photosensitive drum 413 with a developing region therebetween. For example, the developing sleeve has a DC developing bias (for example, −400 [V]) having the same polarity as the charging polarity of the charging device 414 or a developing in which a DC voltage having the same polarity as the charging polarity of the charging device 414 is superimposed on an AC voltage. A bias is applied, that is, a voltage for forming a developing electric field for transferring toner from the developing sleeve to the photosensitive drum 413 in order to develop the electrostatic latent image. As a result, reverse development is performed in which toner is attached to the electrostatic latent image formed by the exposure device 411.

  The drum cleaning device 415 is in contact with the surface of the photosensitive drum 413 and has a plate-like drum cleaning blade 415A made of an elastic material, etc., and remains on the surface of the photosensitive drum 413 without being transferred to the intermediate transfer belt 421. Remove toner.

  The charge amount adjustment unit 416 is provided on the upstream side of the drum cleaning blade 415A and the downstream side of the primary transfer nip in the rotation direction of the photosensitive drum 413, and is applied to the intermediate transfer belt 421 by applying a predetermined voltage. First, the charge amount of the toner remaining on the surface of the photosensitive drum 413 is adjusted. The charge amount adjustment unit 416 includes a corotron charger using corona discharge, a scorotron charger, a static elimination cloth using a static elimination needle, a nonwoven fabric, or the like, or an electrode or a roller provided with a minute gap and facing the photosensitive drum 413 Alternatively, anything that can adjust the charge amount of the toner, such as a contact roller, may be used.

  The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, a belt cleaning device 426, and the like.

  The intermediate transfer unit 42 is composed of an endless belt, and is stretched around a plurality of support rollers 423 in a loop shape. At least one of the plurality of support rollers 423 is configured by a driving roller, and the other is configured by a driven roller. For example, it is preferable that the roller 423A disposed downstream of the K component primary transfer roller 422 in the belt traveling direction is a drive roller. This makes it easy to keep the belt running speed at the primary transfer nip constant. As the driving roller 423A rotates, the intermediate transfer belt 421 travels in the direction of arrow A at a constant speed.

  The intermediate transfer belt 421 is a belt having conductivity and elasticity, and has a high resistance layer having a volume resistivity of 8 to 11 [log Ω · cm] on the surface. The intermediate transfer belt 421 is rotationally driven by a control signal from the control unit 100. Note that the material, thickness, and hardness of the intermediate transfer belt 421 are not limited as long as they have conductivity and elasticity.

  The primary transfer roller 422 is disposed on the inner peripheral surface side of the intermediate transfer belt 421 so as to face the photosensitive drum 413 of each color component. The primary transfer roller 422 is pressed against the photosensitive drum 413 with the intermediate transfer belt 421 interposed therebetween, thereby forming a primary transfer nip for transferring a toner image from the photosensitive drum 413 to the intermediate transfer belt 421.

  The secondary transfer roller 424 is disposed on the outer peripheral surface side of the intermediate transfer belt 421 so as to face the roller 423B disposed on the downstream side in the belt traveling direction of the drive roller 423A. The secondary transfer roller 424 is pressed against the backup roller 423B with the intermediate transfer belt 421 interposed therebetween, thereby forming a secondary transfer nip for transferring the toner image from the intermediate transfer belt 421 to the paper S.

  When the intermediate transfer belt 421 passes through the primary transfer nip, the toner images on the photoconductive drum 413 are primarily transferred onto the intermediate transfer belt 421 in sequence. Specifically, a primary transfer bias is applied to the primary transfer roller 422, and an electric charge having a polarity opposite to that of the toner is applied to the back side of the intermediate transfer belt 421 (the side in contact with the primary transfer roller 422). It is electrostatically transferred to the intermediate transfer belt 421.

  Thereafter, when the sheet S passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred to the sheet S. Specifically, a toner image is applied by applying a secondary transfer bias to the secondary transfer roller 424 and applying a charge having a polarity opposite to that of the toner to the back side of the paper S (the side in contact with the secondary transfer roller 424). Is electrostatically transferred to the paper S. The sheet S to which the toner image is transferred is conveyed toward the fixing unit 60.

  The belt cleaning device 426 removes transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer. Instead of the secondary transfer roller 424, a configuration (so-called belt-type secondary transfer unit) in which a secondary transfer belt is looped around a plurality of support rollers including the secondary transfer roller is adopted. Also good.

  The fixing unit 60 includes an upper fixing unit 60A having a fixing surface side member disposed on the fixing surface (surface on which the toner image is formed) of the paper S, and the back surface (surface opposite to the fixing surface) of the paper S. A lower fixing unit 60B having a rear surface side support member to be disposed, a heating source 60C, and the like are provided. When the back surface side support member is pressed against the fixing surface side member, a fixing nip for nipping and transporting the sheet S is formed.

  The fixing unit 60 fixes the toner image on the paper S by heating and pressurizing the paper S on which the toner image is secondarily transferred and conveyed at the fixing nip. The fixing unit 60 is disposed in the fixing device F as a unit. The fixing device F may be provided with an air separation unit that separates the sheet S from the fixing surface side member or the back surface side support member by blowing air.

  The paper transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, a transport path unit 53, and the like. In the three paper feed tray units 51a to 51c constituting the paper feed unit 51, paper S (standard paper, special paper) identified based on basis weight, size, etc. is stored for each preset type. . The conveyance path unit 53 includes a plurality of conveyance rollers such as a registration roller body 53a.

  The sheets S stored in the sheet feed tray units 51 a to 51 c are sent one by one from the top and are conveyed to the image forming unit 40 by the conveyance path unit 53. At this time, the registration roller portion provided with the registration roller body 53a corrects the inclination of the fed paper S and adjusts the conveyance timing. In the image forming unit 40, the toner image on the intermediate transfer belt 421 is secondarily transferred onto one side of the sheet S at a time, and a fixing process is performed in the fixing unit 60. The sheet S on which the image has been formed is discharged out of the apparatus by a discharge unit 52 having a discharge roller 52a.

  Next, a specific configuration of the developing device 412 will be described. As shown in FIG. 3, the developing device 412 develops toner on the electrostatic latent image formed on the photosensitive drum 413 (that is, the toner in the developing device 412 is consumed) from the developer hopper 417. The toner and carrier to which the first and second lubricants having lubricity are added are supplied. The first and second lubricants will be described later. The developing device 412 stirs the supplied toner and carrier with the stirring screw 412A to charge the toner. The developer (toner and carrier) after stirring is conveyed to the supply roller 412C by the supply screw 412B.

  The supply roller 412C includes a rotatable supply sleeve and a supply magnet roll disposed inside the supply sleeve. A plurality of magnetic poles for generating a magnetic field are arranged in the supply magnet roll. The developer is carried on the outer peripheral surface of the supply sleeve by the magnetic field generated by the magnetic pole, and is conveyed to the developing roller 412D by the rotation of the supply sleeve.

  In the developing roller 412D, the developing sleeve rotates at a predetermined speed around the magnet roller in a fixed state, and the developer is supplied to the outer peripheral surface of the developing sleeve by the supply roller 412C. When the developer supplied to the outer peripheral surface of the developing sleeve moves on the outer peripheral surface of the developing sleeve, the carrier forms a magnetic brush by the magnetic force of the magnetic pole provided on the magnet roller. The toner attached to the magnetic brush adheres to the electrostatic latent image on the photosensitive drum 413. That is, the electrostatic latent image on the photosensitive drum 413 is developed with toner. A regulating plate 412E provided in the vicinity of the developing roller 412D regulates the thickness of the developer that adheres to the outer peripheral surface of the developing sleeve so that a predetermined amount of developer is conveyed by the developing sleeve.

  Next, the first and second lubricants will be described. The first lubricant is, for example, a fatty acid metal salt (small-diameter lubricant) having an average particle diameter of 5 [μm] or less. The second lubricant is, for example, a fatty acid metal salt (large diameter lubricant) having an average particle diameter of 10 [μm] or more. As the first and second lubricants, fatty acid metal salts having high lubricity are preferably used. In the developing device 412, the charged polarity of the first and second lubricants is the charged polarity of the toner after stirring (minus polarity in the present embodiment) and the opposite polarity (plus polarity in the present embodiment). In addition to the fatty acid metal salt, silicone oil, fluorine resin, or the like can be used as the first and second lubricants.

  FIG. 4A is a diagram showing the developer immediately after being supplied from the developer hopper 417 to the developing device 412. As shown in FIG. 4A, the toner 120 (toner particles) is attached to the carrier 110. Further, the first lubricant 130 </ b> A and the second lubricant 130 </ b> B are attached to the toner 120.

  FIG. 4B is a diagram illustrating the developer after being stirred in the developing device 412. As shown in FIG. 4B, the first lubricant 130A is attached to the toner 120 by the stirring operation of the stirring screw 412A, but the second lubricant 130B is detached from the toner 120.

  FIG. 5 is an explanatory diagram for explaining the behavior of the first and second lubricants 130A and 130B. Here, in the image forming process for forming an image on the paper S, the image portion potential (exposure potential) and the background portion potential (charging potential) on the photosensitive drum 413 are set to −50 [V] and −500 [V], respectively. A case where the developing bias applied to the developing sleeve is set to −400 [V] will be described. In this case, the toner 120 and the first lubricant 130A adhering to the toner 120 receive a developing electric field (electrostatic attractive force) acting between the developing sleeve and the photosensitive drum 413, and the photosensitive drum from the developing sleeve. The process proceeds to the image portion on 413. In other words, the first lubricant 130A exhibits the same behavior as the toner 120 with respect to the developing electric field. The second lubricant 130 </ b> B released from the toner 120 receives a developing electric field acting between the developing sleeve and the photosensitive drum 413, and moves from the developing sleeve to the background portion on the photosensitive drum 413. That is, the second lubricant 130B behaves differently from the toner 120 with respect to the developing electric field.

  As described with reference to FIG. 5, the first lubricant 130 </ b> A moves from the developing sleeve to the image portion on the photosensitive drum 413 by the execution of the image forming process, and the second lubricant 130 </ b> B moves from the developing sleeve to the photosensitive drum 413. By shifting to the upper background portion, the lubricant is coated over the entire image forming area on the photosensitive drum 413 regardless of the printing rate of the input image in the image forming process. Accordingly, it is possible to prevent the amount of lubricant supplied to the surface of the photosensitive drum 413 and thus the coverage rate from being lowered, and the occurrence of image defects such as defective cleaning and further FD streaks. In addition, since a portion with a large amount of lubricant coating and a portion with a small amount of lubricant are not generated on the photosensitive drum 413, the surface potential on the photosensitive drum 413 is not uniform, and an image density step (image defect) may occur. Can be prevented.

  However, if an image with a low printing rate or a high printing rate is continuously printed, either the first lubricant 130A or the second lubricant 130B may be depleted earlier in the developing device 412 than the other. Therefore, in the present embodiment, the control unit 100 appropriately adjusts the weight ratio of the first lubricant 130A and the second lubricant 130B in the developing device 412 so as to be independent of the input image printing rate for the image forming process. Then, control for stably supplying the lubricant onto the photosensitive drum 413 (hereinafter referred to as lubricant adjustment control) is performed.

  FIG. 6 is a flowchart showing the lubricant adjustment control operation of the image forming apparatus 1 according to the present embodiment. In the processing in FIG. 6, for example, the control unit 100 receives an instruction to execute a print job.

  First, the control unit 100 reads the image formation information stored in the storage unit 72, and acquires the print rate of the input image related to the print job (step S100).

制御部１００が第１重量比率を設定する際に参照する一例として表１を示したが、制御部１００は任意に第１重量比率を設定するようにしても良い。 Next, the control unit 100 determines a first weight ratio (= first lubricant 130A) that is a target weight ratio of the first lubricant 130A and the second lubricant 130B in the developing device 412 according to the printing rate acquired in step S100. (Weight of second lubricant 130B) is determined (step S110). Specifically, as shown in Table 1 below, the control unit 100 determines the first weight ratio so that the first weight ratio increases as the printing rate increases. For example, when the printing rate is 10 [%], the control unit 100 sets 0.11 as the value of the first weight ratio.

Although Table 1 is shown as an example to be referred to when the control unit 100 sets the first weight ratio, the control unit 100 may arbitrarily set the first weight ratio.

  Next, the control unit 100 obtains the discharge weight of the first lubricant 130A from the developing device 412 to the photosensitive drum 413 (for example, the cumulative print number × the average print rate when the cumulative print number is printed) ( Step S120).

  Next, the control unit 100 discharges the second lubricant 130B from the developing device 412 to the photosensitive drum 413 (for example, cumulative print number × (1−average print rate when the cumulative print number is printed)). Is acquired (step S130).

  Next, the control unit 100 supplies the first lubricant 130A supplied from the developer hopper 417 to the developing device 412 (for example, cumulative printing number × average printing rate when the cumulative printing number is printed × developing device 412 The ratio of the first lubricant 130A) is acquired. Note that the control unit 100 uses the developer replenishment signal output from the control unit 100 to the developer hopper 417 as the supplied weight of the first lubricant 130A (that is, the cumulative number of printed sheets × the average number when the cumulative number of printed sheets is printed). The ratio of the first lubricant 130A in the developing device 412 may be acquired. Further, the control unit 100 supplies the second lubricant 130B from the developer hopper 417 to the developing device 412 (for example, the cumulative number of printed sheets × the average printing rate when the cumulative number of printed sheets is printed × the first number in the developing device 412). 2) (the ratio of two lubricants 130B) is acquired (step S140). Note that the control unit 100 supplies the developer replenishment signal output from the control unit 100 to the developer hopper 417 as the supplied weight of the second lubricant 130B (that is, the cumulative number of printed sheets × the average number when the cumulative number of printed sheets is printed). The ratio of the second lubricant 130B in the developing device 412 may be acquired.

  Next, the control unit 100 determines the second weight that is the actual weight ratio of the first lubricant 130A and the second lubricant 130B in the developing device 412 according to the discharge weight and the supply weight acquired in steps S120 to S140. The ratio (= weight of the first lubricant 130A / weight of the second lubricant 130B) is calculated (step S150).

  Next, the control unit 100 determines whether or not the first weight ratio determined in step S110 is equal to the second weight ratio calculated in step S150 (step S160). As a result of the determination, when the first weight ratio is equal to the second weight ratio (step S160, YES), the control unit 100 determines that the weights of the first lubricant 130A and the second lubricant 130B in the developing device 412 are the photosensitive drum 413. From the viewpoint of stably supplying the lubricant, it is judged to be an appropriate amount. Then, the image forming apparatus 1 ends the process in FIG.

  On the other hand, when the first weight ratio is not equal to the second weight ratio (step S160, NO), the control unit 100 determines whether or not the first weight ratio is less than the second weight ratio (step S170). As a result of the determination, when the first weight ratio is less than the second weight ratio (step S170, YES), the control unit 100 performs control to discharge the first lubricant 130A from the developing device 412 to the photosensitive drum 413 (step S170). S180). Specifically, the control unit 100 selectively irradiates light on the entire surface of the lubricant discharge area on the surface of the photosensitive drum 413 uniformly charged by the charging device 414 with the exposure device 411, and applies it to the developing sleeve. By applying a developing bias, the toner 120 and the first lubricant 130A are discharged to the lubricant discharge region (image portion). As shown in FIG. 7, the lubricant discharge area 150 is formed between the toner image forming areas 140 where the toner image corresponding to the input image data is formed in the rotation direction of the photosensitive drum 413 on the surface of the photosensitive drum 413, that is, It is located between the toner image forming area 140 and the next toner image forming area 140 (between images). The lubricant discharge area 150 is the same as the toner image forming area 140 in the axial direction (main scanning direction) of the photosensitive drum 413. When the toner 120 and the first lubricant 130A are discharged to the lubricant discharge area, new toner 120, the first lubricant 130A, and the second lubricant 130B are supplied from the developer hopper 417 to the developing device 412. Thereby, the fall of the lubricant amount in the developing device 412 can be suppressed while the second weight ratio is brought close to the first weight ratio. Thereafter, the process proceeds to step S200.

  On the other hand, when the first weight ratio is not less than the second weight ratio (step S170, NO), the control unit 100 performs control to discharge the second lubricant 130B from the developing device 412 to the photosensitive drum 413 (step S190). Specifically, the control unit 100 does not selectively irradiate the exposure device 411 with light on the entire surface of the lubricant discharge area on the surface of the photosensitive drum 413 uniformly charged by the charging device 414, and develops the developing sleeve. By applying a developing bias to the second lubricant 130B, the second lubricant 130B is discharged to the lubricant discharge region (background portion). When the second lubricant 130B is discharged to the lubricant discharge area, new toner 120, the first lubricant 130A, and the second lubricant 130B are supplied from the developer hopper 417 to the developing device 412. Thereby, the fall of the lubricant amount in the developing device 412 can be suppressed while the second weight ratio is brought close to the first weight ratio. Thereafter, the process proceeds to step S200.

  In step S200, the control unit 100 acquires the discharge weights of the first lubricant 130A and the second lubricant 130B in steps S180 and S190, and calculates the second weight ratio in the same manner as in step S150. Thereafter, the process returns to before step S160, and a determination process is performed as to whether or not the first weight ratio is equal to the second weight ratio (step S160).

  As described above in detail, the image forming apparatus 1 according to the present exemplary embodiment uses the photosensitive drum 413 and the toner against the development electric field for developing the electrostatic latent image formed on the photosensitive drum 413 with the toner 120. And a developing device 412 that houses a first lubricant 130A that exhibits the same behavior as 120 and a second lubricant 130B that exhibits a behavior different from that of the toner 120. According to this embodiment configured as described above, the first lubricant 130A is transferred from the developing sleeve to the image portion on the photosensitive drum 413 by the execution of the image forming process, and the second lubricant 130B is transferred from the developing sleeve to the photosensitive member. By shifting to the background portion on the drum 413, the lubricant is coated over the entire image forming area on the photosensitive drum 413 regardless of the printing rate of the input image in the image forming process. Accordingly, it is possible to prevent the amount of lubricant supplied to the surface of the photosensitive drum 413 and thus the coverage rate from being lowered, and the occurrence of image defects such as defective cleaning and further FD streaks. In addition, since a portion with a large amount of lubricant coating and a portion with a small amount of lubricant are not generated on the photosensitive drum 413, the surface potential on the photosensitive drum 413 is not uniform, and an image density step (image defect) may occur. Can be prevented. Furthermore, unlike the prior art, it is not necessary to provide a lubricant application means, so that the size of the apparatus and the control are not complicated.

  Further, in the present embodiment, the control unit 100 determines the first weight ratio of the first and second lubricants 130A and 130B according to the image formation information in the developing device 412 and the first and second current values in the developing device 412. Based on the second weight ratio of the lubricants 130A and 130B, the weights of the first and second lubricants 130A and 130B in the developing device 412 are adjusted. Specifically, the control unit 100 supplies (discharges) the first lubricant 130A onto the photosensitive drum 413 with the toner 120, and supplies the second lubricant 130B onto the photosensitive drum 413 without the toner 120. (Exhaust) adjusts the weight of the first and second lubricants 130A and 130B. With this configuration, the first lubricant 130A and the second lubricant 130B are prevented from being depleted in the developing device 412 and stabilized on the photosensitive drum 413 regardless of the input image printing rate for the image forming process. The lubricant (the first lubricant 130A and the second lubricant 130B) can be supplied.

  In the above embodiment, an example in which the charging polarity of the first and second lubricants 130A and 130B is opposite to the charging polarity of the toner 120 after stirring in the developing device 412 has been described. Not limited to this. For example, the charging polarity of the first lubricant 130A may be the same as the charging polarity of the toner 120, while the charging polarity of the second lubricant 130B may be opposite to the charging polarity of the toner 120. Thus, even if the first lubricant 130A is detached from the toner due to stress on the developer due to agitation, the first lubricant 130A can be supplied together with the toner from the developing sleeve to the image portion on the photosensitive drum 413.

  In the above embodiment, the control unit 100 has been described with respect to the example in which the print rate of the input image related to the print job is acquired and the first weight ratio is determined according to the acquired print rate. It is not limited to. For example, the control unit 100 acquires the surface potential of the photosensitive drum 413 that indirectly indicates the printing rate of the input image related to the print job by a known means (for example, a surface potential detection sensor), Specifically, the first weight ratio may be determined according to the ratio of the exposed area in the toner image forming area 140.

  In the above-described embodiment, the control unit 100 discharges the first lubricant 130A onto the photosensitive drum 413 with the toner 120, and discharges the second lubricant 130B onto the photosensitive drum 413 without the toner 120. Thus, the example of adjusting the weight of the first and second lubricants 130A and 130B in the developing device 412 has been described, but the present invention is not limited to this. For example, the weight of the first and second lubricants 130A and 130B in the developing device 412 may be adjusted by supplying the first lubricant 130A to the developing device 412 and supplying the second lubricant 130B to the developing device 412. Thereby, it is possible to suppress excessive toner consumption only for adjusting the weights of the first and second lubricants 130A and 130B. Further, the first and second lubricants 130A and 130B can be supplied at an arbitrary timing as compared with the case where the first and second lubricants 130A and 130B are discharged aiming at the timing between the toner image forming areas 140. The weight ratio of the first and second lubricants in the developing device 412 can be adjusted efficiently in a short period of time. The configuration in this case will be described with reference to FIG.

  As shown in FIG. 8, developer hoppers 417 </ b> A and 417 </ b> B are connected to the developing device 412. Developer hopper 417A (corresponding to “first lubricant accommodating portion” of the present invention) accommodates a first developer including toner 120 and first lubricant 130A. The developer hopper 417B (corresponding to the “second lubricant accommodating portion” of the present invention) accommodates the second developer including the toner 120 and the second lubricant 130B. The control unit 100 controls the developer hoppers 417A and 417B, supplies the first developer from the developer hopper 417A to the developing device 412, and supplies the second developer to the developing device 412 from the developer hopper 417B. Then, the weights of the first and second lubricants 130A and 130B in the developing device 412 are adjusted.

For example, as the printing rate of the input image decreases, the control unit 100 compares the developer hopper 417B with the first lubricant supply weight that is the weight of the first lubricant 130A supplied from the developer hopper 417A to the developing device 412. To the developing device 412, the second lubricant supply weight which is the weight of the second lubricant 130 </ b> B supplied to the developing device 412 is adjusted to be larger. As one aspect thereof, as shown in Table 2 below, the control unit 100 adjusts the first lubricant supply weight / (first lubricant supply weight + second lubricant supply weight) and the printing rate to be proportional. Also good. As a result, the first and second lubricants 130A and 130B are supplied at the same lubricant ratio as the first weight ratio, and the first and second lubricants 130A and 130B in the developing device 412 are reduced to the first weight ratio in a short period of time. Can be approached.

  In the configuration of FIG. 8, the developer hopper 417B may accommodate only the second lubricant 130B. In this case, the control unit 100 controls the developer hoppers 417A and 417B, supplies the first developer to the developing device 412 from the developer hopper 417A, and supplies the second lubricant 130B to the developing device 412 from the developer hopper 417B. By adjusting the weight, the weights of the first and second lubricants 130A and 130B in the developing device 412 are adjusted. With this configuration, when the image having a low printing rate is continuously printed, that is, when the consumption amount of the toner 120 is small and the supply weight of the second lubricant 130B to the photosensitive drum 413 is large, the developer hopper 417B supplies the second lubricant. Only 130B can be supplied to the developing device 412, which is preferable.

  FIG. 9 is a flowchart showing the lubricant adjustment control operation of the image forming apparatus 1 having the configuration of FIG. The processing in steps S300 and S420 in FIG. 9 is executed each time the control unit 100 receives a print job execution instruction, for example.

  First, the control unit 100 reads the image formation information stored in the storage unit 72 and acquires the print rate of the input image related to the print job (step S300). Next, the control unit 100 determines the first weight ratio according to the printing rate acquired in step S100 (step S310).

  Next, the control unit 100 acquires the discharge weight of the first lubricant 130A from the developing device 412 to the photosensitive drum 413 by means similar to step S120 in FIG. 6 (step S320). Next, the control unit 100 acquires the discharge weight of the second lubricant 130B from the developing device 412 to the photosensitive drum 413 by the same means as in step S130 of FIG. 6 (step S330).

  Next, the control unit 100 supplies the first lubricant 130A supplied from the developer hopper 417A to the developing device 412 (for example, the cumulative number of replenishment signals of the first lubricant 130A output from the control unit 100 to the developer hopper 417A). X Acquire the ratio of the first lubricant 130A in the first and second lubricants 130A, 130B supplied per supply signal (step S340). Next, the control unit 100 supplies the second lubricant 130B supplied from the developer hopper 417B to the developing device 412 (for example, the cumulative number of replenishment signals of the second lubricant 130B output from the control unit 100 to the developer hopper 417B). × Acquire the ratio of the second lubricant 130B to the first and second lubricants 130A and 130B supplied per supply signal (step S350).

  Next, the control unit 100 determines the second weight that is the actual weight ratio of the first lubricant 130A and the second lubricant 130B in the developing device 412 according to the discharge weight and supply weight acquired in steps S320 to S350. The ratio is calculated (step S360). Thereafter, the process transitions to steps S370 and S430.

  In step S370, the control unit 100 determines whether or not the first weight ratio determined in step S310 is equal to the second weight ratio calculated in step S350. As a result of the determination, when the first weight ratio is equal to the second weight ratio (step S370, YES), the control unit 100 determines that the weight of the first lubricant 130A and the second lubricant 130B in the developing device 412 is equal to the photosensitive drum 413. From the viewpoint of stably supplying the lubricant, it is judged to be an appropriate amount. Then, the image forming apparatus 1 ends the process in FIG.

  On the other hand, when the first weight ratio is not equal to the second weight ratio (step S370, NO), the control unit 100 determines whether or not the first weight ratio is less than the second weight ratio (step S380). As a result of the determination, when the first weight ratio is less than the second weight ratio (step S380, YES), the control unit 100 performs control to discharge the first lubricant 130A from the developing device 412 (step S390). Thereafter, the process proceeds to step S410.

  On the other hand, when the first weight ratio is not less than the second weight ratio (step S380, NO), the control unit 100 performs control to discharge the second lubricant 130B from the developing device 412 (step S400). Thereafter, the process proceeds to step S410.

  In step S410, the control unit 100 acquires the supply weight of the first lubricant 130A and the second lubricant 130B in steps S390 and S400, and calculates the second weight ratio in the same manner as in step S360. Thereafter, the process returns to before step S370, and a determination process is performed as to whether or not the first weight ratio is equal to the second weight ratio (step S370).

  In step S420, the control unit 100 outputs a developer replenishment signal based on, for example, a density detection result of a toner density detection sensor provided in the developing device 412 (for example, the toner density is equal to or lower than a predetermined density). It is determined whether or not it is necessary to do this (step S420). As a result of the determination, when it is not necessary to output a developer supply signal (step S420, NO), the image forming apparatus 1 ends the processing in FIG.

  On the other hand, when it is necessary to output a developer supply signal (step S420, YES), the control unit 100 determines whether or not the first weight ratio is equal to the second weight ratio (step S430). As a result of the determination, when the first weight ratio is equal to the second weight ratio (step S430, YES), the image forming apparatus 1 ends the process in FIG.

  On the other hand, when the first weight ratio is not equal to the second weight ratio (step S430, NO), the control unit 100 determines whether or not the first weight ratio is less than the second weight ratio (step S440). As a result of the determination, when the first weight ratio is less than the second weight ratio (step S440, YES), the control unit 100 performs control to supply the second lubricant 130B from the developer hopper 417B to the developing device 412 (step S450). ). On the other hand, when the first weight ratio is not less than the second weight ratio (step S440, NO), the control unit 100 performs control to supply the first lubricant 130A from the developer hopper 417A to the developing device 412 (step S460).

  In addition, each of the above-described embodiments is merely an example of a specific example for carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the gist or the main features thereof.

  The present invention can be applied to an image forming system including a plurality of units including an image forming apparatus. The plurality of units include external devices such as post-processing devices and network-connected control devices, for example.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Image reading part 20 Operation display part 21 Display part 22 Operation part 30 Image processing part 40 Image formation part 50 Paper conveyance part 60 Fixing part 71 Communication part 72 Storage part 100 Control part 101 CPU
102 ROM
103 RAM
120 Toner 130A First lubricant 130B Second lubricant 412 Developing device 413 Photosensitive drums 417, 417A, 417B Developer hopper

Claims (15)

An image carrier;
A first lubricant that exhibits the same behavior as the toner with respect to a developing electric field for developing the electrostatic latent image formed on the image carrier with toner, and a second lubricant that exhibits a behavior different from that of the toner are contained. A lubricant containing part,
An image forming apparatus comprising: An adjusting portion for adjusting the weight of the first and second lubricants in the lubricant accommodating portion;
A control unit that controls the adjusting unit so as to adjust the weight of the first and second lubricants in the lubricant accommodating unit based on image formation information relating to image formation;
An image forming apparatus according to claim 1. The control unit includes a first weight ratio of the first and second lubricants according to the image formation information in the lubricant container, and a current second weight ratio of the first and second lubricants in the lubricant container. Based on the control of the adjustment unit to adjust the weight of the first and second lubricant in the lubricant storage unit,
The image forming apparatus according to claim 2. The adjusting unit supplies the first lubricant onto the image carrier with the toner, and supplies the second lubricant onto the image carrier without the toner, thereby providing the lubricant container. Adjusting the weight of the first and second lubricants in
The image forming apparatus according to claim 2. The image formation information includes a printing rate of the input image,
The image forming apparatus according to claim 2. The image formation information includes a surface potential of the image carrier.
The image forming apparatus according to claim 2. The first lubricant has an average particle size of 5 [μm] or less,
The second lubricant has an average particle size of 10 [μm] or more,
The image forming apparatus according to claim 1. The charging polarity of the first lubricant is the same as the charging polarity of the toner,
The charging polarity of the second lubricant is opposite to the charging polarity of the toner.
The image forming apparatus according to claim 1. The first and second lubricants are fatty acid metal salts,
The image forming apparatus according to claim 1. A first lubricant accommodating portion for accommodating the toner and the first lubricant;
A second lubricant accommodating portion for accommodating the toner and the second lubricant;
With
The adjustment unit supplies the toner and the first lubricant from the first lubricant container to the lubricant container, and supplies the toner and the second lubricant from the second lubricant container to the lubricant container. By adjusting the weight of the first and second lubricants in the lubricant accommodating portion,
The image forming apparatus according to claim 2. The image formation information is a printing rate of the input image,
The control unit stores the second lubricant as compared with a first lubricant supply weight that is a weight of the first lubricant supplied from the first lubricant storage to the lubricant storage as the printing rate becomes lower. Adjusting the adjustment unit such that the second lubricant supply weight, which is the weight of the second lubricant supplied from the unit to the lubricant accommodating unit, is increased.
The image forming apparatus according to claim 10. The control unit adjusts the adjustment unit so that the first lubricant supply weight / (the first lubricant supply weight + the second lubricant supply weight) is proportional to the printing rate.
The image forming apparatus according to claim 11. A first lubricant accommodating portion for accommodating the toner and the first lubricant;
A second lubricant accommodating portion for accommodating the second lubricant;
With
The adjusting unit supplies the toner and the first lubricant from the first lubricant container to the lubricant container, and supplies the second lubricant from the second lubricant container to the lubricant container. Adjusting the weight of the first and second lubricants in the lubricant accommodating portion;
The image forming apparatus according to claim 2. An image forming system including a plurality of units including an image forming apparatus,
An image carrier;
A first lubricant that exhibits the same behavior as the toner with respect to a developing electric field for developing the electrostatic latent image formed on the image carrier with toner, and a second lubricant that exhibits a behavior different from that of the toner are contained. A lubricant containing part,
An image forming system comprising: A lubricant containing portion containing a first lubricant exhibiting the same behavior as the toner with respect to a developing electric field for developing the electrostatic latent image formed on the image bearing member with toner, and a second lubricant exhibiting a behavior different from that of the toner. Housed in
Adjusting the weight of the first and second lubricants in the lubricant accommodating portion based on image formation information relating to image formation;
Lubricant adjustment control method.

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