Image forming apparatus, lubricant unevenness detection method, and program

Abstract

To provide an image forming apparatus, a lubricant unevenness detection method, and a program that suitably detect unevenness in the amount of application of lubricant occurring in a main scanning direction on an image carrier.SOLUTION: An image forming apparatus comprises an image forming unit having image carriers that each carry a toner image, lubricant application units that each apply lubricant to the image carrier, and cleaning units that each remove a toner remaining on the surface of the image carrier with a blade. The image forming apparatus comprises: a toner patch supply unit that supplies, onto the image carriers, toner patches in an oblique striped pattern at an equal interval in a main scanning direction; a measuring unit that measures the physical quantities in the image carriers and the blades during a cleaning operation of the image carriers on which the toner patches are formed; and a determination unit that determines the presence or absence of unevenness in the amount of application of the lubricant on the image carriers in the main scanning direction on the basis of measurements measured by the measuring unit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an image forming apparatus, a lubricant unevenness detection method, and a program.

Background Art

[0002] Generally, in an image forming apparatus using an electrophotographic process, when transferring the toner image on the photoreceptor to the intermediate transfer belt, some toner particles remain on the photoreceptor without being transferred. Therefore, the image forming apparatus is provided with a cleaning device for removing residues such as residual toner on the photoreceptor. However, when the adhesion force between the toner particles and the photoreceptor is large, the cleaning device cannot sufficiently remove the residues on the photoreceptor, resulting in cleaning failure.

[0003] Therefore, a technique is known in which a lubricant is applied to the photoreceptor to reduce the adhesion force between the toner particles and the photoreceptor and suppress cleaning failure. However, in a portion where the application amount of the lubricant is small, the residues on the photoreceptor cannot be sufficiently cleaned. As a result, the toner particles slip through the cleaning blade, and vertical streaks occur on the formed image. Therefore, it is preferable that the lubricant be uniformly applied in an appropriate amount on the photoreceptor.

[0004] As a method for detecting the application state of the lubricant on the photoreceptor, techniques for measuring the driving torque of the photoreceptor during white solid printing or during the lubricant application operation are disclosed (Patent Documents 1 and 2). In addition, a technique for determining whether there is lubricant application unevenness based on the partial toner input amount in the main scanning direction of the photoreceptor is also disclosed (Patent Document 3).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] By the way, it has been found that unevenness in the amount of lubricant applied, which is the cause of vertical streaks, occurs with a regular pitch in the main scanning direction of the photoreceptor. This is considered to occur because the edge of the cleaning blade is locally pulled in the rotational direction of the photoreceptor at periodic intervals in the main scanning direction due to coverage, the installation environment of the apparatus, etc. As a result, unevenness in the amount of lubricant applied occurs on the photoreceptor.

[0007] In the techniques disclosed in Patent Document 1 and Patent Document 2, the average amount of lubricant applied to the entire photoreceptor can be detected, but the unevenness in the amount of lubricant applied occurring in the main scanning direction cannot be detected. Also, in the technique disclosed in Patent Document 3, the unevenness in the amount of lubricant applied occurring in the main scanning direction cannot be detected.

[0008] Also, vertical streaks do not occur immediately after the unevenness in the amount of lubricant applied occurs. Instead, the state in which the unevenness has occurred continues for a while, damage accumulates on the cleaning blade, and finally vertical streaks occur. Therefore, by quickly detecting the unevenness in the amount of lubricant applied on the photoreceptor, the occurrence of vertical streaks can be prevented.

[0009] The problem to be solved by the present invention is to provide an image forming apparatus, a lubricant unevenness detection method, and a program that suitably detect unevenness in the amount of lubricant applied in the main scanning direction on an image carrier.

MEANS FOR SOLVING THE PROBLEM

[0010] To solve the above problems, an image forming apparatus of the present invention is an image forming apparatus including an image forming unit having an image carrier that carries a toner image, a lubricant application unit that applies a lubricant to the image carrier, and a cleaning unit that cleans toner remaining on the surface of the image carrier with a blade. a toner patch supply unit that supplies toner patches with diagonal stripe patterns at equal intervals in the main scanning direction onto the image carrier; a measurement unit that measures physical quantities of the image carrier and the blade during the cleaning operation of the image carrier on which the toner patches are formed; a determination unit that determines the presence or absence of unevenness in the coating amount of the lubricant in the main scanning direction on the image carrier based on the measurement value measured by the measurement unit.

[0011] The invention according to claim 2 is the invention according to claim 1, wherein the measurement unit includes a torque sensor that measures the driving torque of the image carrier as the physical quantity.

[0012] The invention according to claim 3 is the invention according to claim 1, wherein the measurement unit includes a sensor that directly or indirectly measures the vibration of the blade as the physical quantity.

[0013] The invention according to claim 4 is the invention according to claim 3, wherein the cleaning unit includes a holding member that holds the blade, the measurement unit includes an acceleration sensor that measures the vibration of the holding member as the physical quantity.

[0014] The invention according to claim 5 is the invention according to claim 3, wherein the cleaning unit holds the blade via a spring, the measurement unit includes a permeability sensor that measures the vibration of the spring as the physical quantity.

[0015] The invention according to claim 6 is the invention according to claim 1, wherein the toner patch supply unit supplies the toner patches by dividing them in the main scanning direction.

[0016] The invention according to claim 7 is the invention according to claim 1, wherein The toner patch supply unit supplies a plurality of the toner patches with different intervals.

[0017] The invention according to claim 8 is the invention according to claim 1, wherein When it is determined by the determination unit that unevenness in the coating amount of the lubricant has occurred, a control unit is provided that causes the lubricant application unit to perform a recovery process for eliminating the unevenness in the coating amount.

[0018] The invention according to claim 9 is the invention according to claim 8, wherein The control unit causes the lubricant application unit to perform a recovery process for increasing the coating amount of the lubricant on the image carrier.

[0019] The invention according to claim 10 is the invention according to claim 9, wherein The lubricant application unit includes a rotary brush that contacts the image carrier and applies the lubricant, The control unit causes the rotary brush to perform a recovery process for increasing the rotation speed.

[0020] The invention according to claim 11 is the invention according to claim 8, wherein The control unit causes the image forming unit to supply toner onto the image carrier to peel off the lubricant on the image carrier, and then causes the lubricant application unit to perform a recovery process for newly applying the lubricant to the image carrier.

[0021] The invention according to claim 12 is the invention according to claim 8, wherein The control unit causes the lubricant to be removed in a region where the coating amount of the lubricant on the image carrier is large, and causes the lubricant application unit to perform a recovery process for applying the lubricant in a region where the coating amount of the lubricant is small.

[0022] The invention according to claim 13 is the invention according to claim 12, wherein The control unit causes the image forming unit to supply toner onto the image carrier, and performs a recovery process for removing the lubricant by making the application amount of the lubricant with respect to the longitudinal position on the image carrier and the supply amount of toner with respect to the longitudinal position on the image carrier in the same phase.

[0023] The lubricant unevenness detection method of the present invention is a lubricant unevenness detection method for an image forming apparatus including an image forming unit having an image carrier that carries a toner image, a lubricant application unit that applies a lubricant to the image carrier, and a cleaning unit that cleans toner remaining on the surface of the image carrier with a blade, a toner patch supply step of supplying toner patches having an oblique stripe pattern at equal intervals in the main scanning direction onto the image carrier, a measurement step of measuring physical quantities of the image carrier and the blade during a cleaning operation of the image carrier on which the toner patch is formed, and a determination step of determining the presence or absence of unevenness in the application amount of the lubricant in the main scanning direction on the image carrier based on the measurement value measured in the measurement step.

[0024] The program of the present invention is for a computer of an image forming apparatus including an image forming unit having an image carrier that carries a toner image, a lubricant application unit that applies a lubricant to the image carrier, and a cleaning unit that cleans toner remaining on the surface of the image carrier with a blade, to execute a toner patch supply process of supplying toner patches having an oblique stripe pattern at equal intervals in the main scanning direction onto the image carrier, a measurement process of measuring physical quantities of the image carrier and the blade during a cleaning operation of the image carrier on which the toner patch is formed, and a determination process of determining the presence or absence of unevenness in the application amount of the lubricant in the main scanning direction on the image carrier based on the measurement value measured in the measurement process.

Advantages of the Invention

[0025] According to the present invention, it is possible to provide an image forming apparatus, a lubricant unevenness detection method, and a program that suitably detect unevenness in the coating amount of a lubricant generated in the main scanning direction on an image carrier.

Brief Description of the Drawings

[0026]

Figure 1

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Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Embodiments for Carrying out the Invention

[0027] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to the disclosed embodiments.

[0028]

Configuration of Image Forming Apparatus 1

[0029] The automatic document feeder 2 includes a placement tray for placing the document D, a mechanism for transporting the document D, and transport rollers, etc., and transports the document D along a predetermined transport path. The scanner unit 3 includes an optical system such as a light source and a reflecting mirror, irradiates the document D transported along a predetermined transport path or the document D placed on the platen glass with a light source, and receives the reflected light. Further, the scanner unit 3 converts the received reflected light into an electrical signal and outputs it to the control unit 10 as image data.

[0030] The image forming unit 4 includes a yellow image forming unit Y, a magenta image forming unit M, a cyan image forming unit C, a black image forming unit K, a white image forming unit W, an intermediate transfer belt T, and a fixing unit F. In the present embodiment, in addition to the four-color image forming units used in normal color printing of yellow, magenta, cyan, and black, a white (white) image forming unit will be described as the fifth-color (special color) image forming unit. As other colors, a clear (transparent) image forming unit or the like may be provided. Further, a sixth-color image forming unit may be provided. Each image forming unit YMCKW forms toner images of yellow, magenta, cyan, black, and white on the photoreceptor 41, and primarily transfers the toner images of each color of YMCKW formed on the photoreceptor 41 to the intermediate transfer belt T.

[0031] FIG. 3 is a diagram showing a schematic configuration of each image forming unit of the image forming unit 4. Each image forming unit includes a photoreceptor 41, a charging device 42, an exposure device 43, a developing device 44, a primary transfer roller 45, a cleaning unit 471, and a lubricant applying unit 472.

[0032] The photoreceptor 41 is drum-shaped and is rotationally driven in the A direction shown in FIG. 3. The charging device 42 uniformly charges the surface of the photoreceptor 41. The exposure device 43 exposes the surface of the photoreceptor 41 charged by the charging device 42 to form an electrostatic latent image. The developing device 44 visualizes the electrostatic latent image formed by the exposure device 43 using a developer containing toner. The primary transfer roller 45 primarily transfers the toner image formed on the photoreceptor 41 to the intermediate transfer belt T that moves in the B direction shown in FIG. 3. The cleaning unit 471 removes the toner on the photoreceptor 41 that has passed through the transfer area. The lubricant applying unit 472 supplies lubricant to the photoreceptor 41.

[0033] The toner image transferred to the intermediate transfer belt T is transferred to the paper P by the secondary transfer roller 46, and then is conveyed to the fixing unit F and fixed on the paper P. The components of each of the above-described image forming units YMCKW are long in the axial direction of the photoreceptor 41. Since the configurations and operations of each of the image forming units YMCKW are the same, a series of image forming operations performed by the image forming unit 4 will be described below by taking the yellow image forming unit Y as an example.

[0034] The photoreceptor 41 is composed 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, and is rotationally driven in the direction of A shown in FIG. 3. Examples of the resin constituting the photosensitive layer include polycarbonate resin, silicone resin, polystyrene resin, acrylic resin, methacrylic resin, epoxy resin, polyurethane resin, vinyl chloride resin, melamine resin, and the like. The photoreceptor 41 has a layer structure in which an undercoat layer (UCL), a charge generation layer (CGL), and a charge transport layer (CTL) are arranged in this order on a conductive base tube such as an aluminum tube.

[0035] The charging device 42 is, for example, of the scorotron type, and uses a charging charger to charge the photoreceptor 41 to a constant potential with a negative polarity.

[0036] The exposure device 43 exposes the non-image area of the photoreceptor 41 based on the image data Dy from the control unit 10 to remove the charges in the exposed part, and forms an electrostatic latent image on the image area of the photoreceptor 41. Specifically, charges are removed from the surface of the photoreceptor 41 charged to a negative polarity by the charging device 42 by the exposure of the exposure device 43. When positive and negative charges are generated by a charge generation material (CGM) in the CGL, the positive charges (holes) pass through the CTL to the surface of the photoreceptor 41, and the negative charges pass through the UCL to reach the base tube. Thereby, an electrostatic latent image is formed on the surface of the photoreceptor 41.

[0037] The developing device 44 includes a developing sleeve 44a arranged to face the photoreceptor 41 via a developing area. A developing bias in which an alternating voltage is superimposed on a direct current voltage of the same polarity as the charging polarity of the charging device 42, that is, a negative polarity, is applied to the developing sleeve 44a. Thereby, a developer is supplied onto the electrostatic latent image formed on the photoreceptor 41, and a yellow toner image is formed on the photoreceptor 41. The developer includes toner and a carrier for charging the toner.

[0038] The toner is not particularly limited, and known toners generally used can be used. For example, as the toner, a material obtained by incorporating a charge control agent, a release agent, etc. as necessary in addition to a colorant in a binder resin and treating with an external additive can be used. The toner particle size is not particularly limited, but is preferably about 3 to 15 μm.

[0039] The primary transfer roller 45 primarily transfers the yellow toner image formed on the photoreceptor 41 to the intermediate transfer belt T. Similarly, in other image forming units MCKW, the magenta, cyan, black, and white toner images are also primarily transferred to the intermediate transfer belt T. As a result, color toner images of each of the YMCKW colors are formed on the intermediate transfer belt T.

[0040] The intermediate transfer belt (intermediate transfer member) T is a semiconductive endless belt suspended by a plurality of rollers and rotatably supported, and is rotationally driven in the direction of B shown in FIG. 3 as the rollers rotate. This intermediate transfer belt T is pressed against each opposing photoreceptor 41 by the primary transfer roller 45. A transfer current corresponding to the applied voltage flows through each of the primary transfer rollers 45. As a result, each toner image developed on the surface of each photoreceptor 41 is sequentially primarily transferred to the intermediate transfer belt T by each primary transfer roller 45.

[0041] The secondary transfer roller 46 rotates in pressure contact with the intermediate transfer belt T via the secondary transfer belt (secondary transfer member) 462. Thereby, the toner images of each of the YMCKW colors transferred and formed on the intermediate transfer belt T are secondarily transferred to the sheet P conveyed from the paper feed trays 51 to 53 of the paper feed unit 5. Specifically, the secondary transfer roller 46 is disposed in contact with the secondary transfer opposing roller 461 via the secondary transfer belt 462 and the intermediate transfer belt T. When the sheet P passes through the transfer nip formed between the secondary transfer roller 46 and the secondary transfer opposing roller 461, the toner image on the intermediate transfer belt T is secondarily transferred to the sheet P. Note that, instead of providing the secondary transfer belt 462, the secondary transfer roller 46 may be configured to be in direct pressure contact with the intermediate transfer belt T. In this case, the secondary transfer roller 46 corresponds to the secondary transfer member of the present invention.

[0042] The toner remaining on the photoreceptor 41 without being transferred onto the intermediate transfer belt T in the transfer region is recovered by the cleaning unit 471. Furthermore, the photoconductor 41 from which the toner on the surface has been collected by the cleaning unit 471 is again charged by the charging device 42, and the next electrostatic latent image is formed, and the process of forming a toner image is repeated.

[0043] The cleaning unit 471 includes a blade portion 47a and a collection screw 47b. As shown in FIG. 4, the blade portion 47a includes a blade a1, a holding member a2, and a spring a3. The blade portion 47a is installed so that the blade a1 slides against the photoconductor 41, and scrapes off and removes deposits such as untransferred toner remaining on the surface of the photoconductor 41. The collection screw 47b shown in FIG. 3 is provided substantially below the blade portion 47a. The collection screw 47b rotates in one direction, and transports the toner scraped off by the blade portion 47a and dropped to a waste toner box (not shown).

[0044] The blade a1 is made of an elastic body, for example, polyurethane rubber processed into a flat plate shape. The holding member a2 is plate-shaped, and the blade a1 is fixed to the tip of the holding member a2. The holding member a2 is preferably made of metal, for example, and is preferably a steel plate such as SECC (electro-galvanized steel sheet). The spring a3 is, for example, a compression spring that biases the blade a1 in a direction opposite to the direction in which the blade a1 is wound up as a result of rubbing against the photoconductor 41. The spring a3 presses and holds the blade a1 against the photoconductor 41 via the holding member a2.

[0045] 3, the lubricant application section 472 includes an application brush (rotating brush) 47c, a lubricant rod 47d, a pressing section 47e, and a fixed blade 47f. The application brush 47c is provided downstream of the blade section 47a in the rotation direction of the photoconductor 41. The lubricant rod 47d supplies lubricant to the application brush 47c. The pressing section 47e presses and holds the lubricant rod 47d against the application brush 47c. The fixed blade 47f is provided downstream of the application brush 47c in the rotation direction of the photoconductor 41.

[0046] The coating brush 47c is a roll-shaped brush member disposed at a position where its tip can contact the photoreceptor 41. The coating brush 47c performs counter-rotation, in which the surface advances in a direction opposite to the advancing direction of the surface of the photoreceptor 41, at the contact point with the photoreceptor 41 under the control of the control unit 10, and applies (supplies) a lubricant to the photoreceptor 41.

[0047] The lubricant bar 47d is obtained, for example, by melt-molding and solidifying a powder lubricant of a metal soap such as zinc stearate. The lubricant bar 47d is disposed at a position where the tip of the coating brush 47c can contact it, and is scraped off from the tip by the rotation of the coating brush 47c. The scraped-off lubricant is directly conveyed to the photoreceptor 41 and supplied to the surface of the photoreceptor 41.

[0048] The pressing portion 47e includes, for example, a compression spring that biases the lubricant bar 47d toward the coating brush 47c, and presses and holds the lubricant bar 47d against the coating brush 47c.

[0049] The immobilizing blade 47f is, like the blade portion 47a, made of, for example, an elastomer such as polyurethane rubber processed into a flat plate shape. The immobilizing blade 47f is abutted against the surface of the photoreceptor 41 in the direction of dragging the surface (trailing contact), and its tip is installed so as to rub against the photoreceptor 41.

[0050] This immobilizing blade 47f is for stretching the powder of the lubricant supplied to the surface of the photoreceptor 41 and forming a film (lubricant layer) on the surface of the photoreceptor 41. The lubricant layer formed of zinc stearate is characterized by high releasability, that is, a high pure water contact angle and a small friction coefficient. Therefore, the lubricant layer formed of zinc stearate has good transferability and cleaning properties, and also suppresses the wear of the photoreceptor 41 and can extend its life.

[0051] In addition, the toner and the like remaining on the intermediate transfer belt T without being transferred to the paper P are conveyed to a cleaning unit (cleaning member) 48 including a blade member 48a that abuts against the intermediate transfer belt T, and are removed and recovered by the cleaning unit 48.

[0052] The image forming unit 4 heats and presses the sheet P on which toner images of each of the YMCKW colors are secondarily transferred by the fixing unit F, and then discharges it outside the machine through a predetermined conveyance path. The above is the configuration of the image forming unit 4.

[0053] The paper feeding unit 5 includes a plurality of paper feeding trays 51 to 53, and accommodates a plurality of different types of sheets P in each of the paper feeding trays 51 to 53. The paper feeding unit 5 feeds the sheet P accommodated by a predetermined conveyance path to the image forming unit 4.

[0054] The storage unit 6 is composed of an HDD (Hard Disk Drive), a semiconductor memory, etc. The storage unit 6 stores data such as program data, various setting data, and job information (job setting information and job image data) readably and writably from the control unit 10. The job setting information includes information such as the type and size of the paper used in the job, single-sided / double-sided, total number of printed sheets, application settings, etc.

[0055] The operation display unit 7 is composed of, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 71 and an operation unit 72. The display unit 71 displays various operation screens, the operation status of each function, etc. according to the display control signal input from the control unit 10. Further, it accepts a touch operation by the user and outputs an operation signal to the control unit 10. The operation unit 72 includes various operation keys such as numeric keys and a start key, and a touch panel formed on the display unit 71, accepts various input operations by the user, and outputs an operation signal to the control unit 10. The user can operate the operation display unit 7 to perform settings related to image formation such as image quality setting, magnification setting, application setting, output setting, and paper setting, paper conveyance instruction, and stop operation of the apparatus.

[0056] The communication unit 8 is composed of a communication control card such as a LAN (Local Area Network) card, and performs transmission and reception of various data with external devices connected to a communication network such as a LAN or a WAN (Wide Area Network). For example, the communication unit 8 receives job information from an external device.

[0057] The control unit 10 includes a CPU (Central Processing Unit), a RAM (Random Access Memory ), a ROM (Read Only Memory), etc., and the CPU expands various programs stored in the ROM or the storage unit 6 into the RAM, and in cooperation with the expanded various programs, comprehensively controls the operations of each part of the image forming apparatus 1 such as the automatic document feeder 2, the scanner unit 3, the image forming unit 4, the paper feeding unit 5, the storage unit 6, the operation display unit 7, and the communication unit 8 (see FIG. 2). For example, the control unit 10 stores the job information input by the operation unit 72 and the scanner unit 3 and the job information received by the communication unit 8 in the storage unit 6, and executes a printing control process (see FIG. 7) described later based on an execution instruction of the job.

[0058] The unevenness in the lubricant application amount is detected by the control unit 10 and the measurement unit 11. The control unit 10 supplies toner patches with an oblique stripe pattern at equal intervals in the main scanning direction on the photoreceptor 41 as shown in FIG. 5. At this time, the control unit 10 functions as a toner patch supply unit. The interval of the toner patches in the main scanning direction is the same as the interval of the coating unevenness. The measurement unit 11 measures the physical quantity between the photoreceptor 41 and the blade a1 during the cleaning operation of the photoreceptor 41 to which the toner patches are supplied. The control unit 10 reads out the measurement value obtained by the measurement unit 11, and based on the measurement value, determines the presence or absence of unevenness in the lubricant application amount in the main scanning direction on the photoreceptor 41. At this time, the control unit 10 functions as a determination unit.

[0059] As the measurement unit 11, for example, when measuring the driving torque of the photoreceptor 41 as a physical quantity, a torque sensor is attached to the photoreceptor 41. Also, when directly or indirectly measuring the vibration of the blade a1 as a physical quantity, the following sensors are attached. When measuring the vibration of the holding member a2 as a physical quantity to indirectly measure the vibration of the blade a1, as shown in FIG. 6, an acceleration sensor 111 is attached to the holding member a2. When measuring the vibration of the spring a3 as a physical quantity to indirectly measure the vibration of the blade a1, as shown in FIG. 7, a magnetic body 112 (such as a neodymium magnet) is attached to the arm portion of the spring a3. The magnetic permeability sensor 113 is attached at a position opposite to the spring a3 facing the magnetic body 112.

[0060] The magnetic permeability sensor 113 may be a magnetic permeability sensor used for a TCR (Toner Carrier Ratio) sensor. The TCR sensor is used when detecting the toner concentration of the developer stored in the developing device.

[0061] When it is determined by the control unit 10 and the measurement unit 11 that unevenness in the application amount of the lubricant has occurred, the control unit 10 instructs the image forming unit and the lubricant application unit 472 of the image forming unit 4 to execute a recovery process for eliminating the unevenness in the application amount of the lubricant.

[0062] 〔Operation of the image forming apparatus 1〕 The image forming apparatus 1 detects the occurrence of unevenness in the application amount of the lubricant on the photoreceptor 41. Also, the image forming apparatus 1 can prevent the occurrence of cleaning failures by executing a recovery process for eliminating the unevenness in the application amount of the lubricant. FIG. 8 is a flowchart showing an example of an operation for detecting unevenness in the application amount of the lubricant of the image forming apparatus according to an embodiment of the present invention and preventing cleaning failures. In this specification, the unevenness in the application amount of the lubricant occurring in the main scanning direction of the photoreceptor 41 is also simply referred to as "application unevenness" or "lubricant unevenness".

[0063] In step S11, the control unit 10 instructs the image forming unit 4's image forming section to supply toner patches in the form of diagonal stripes at equal intervals in the main scanning direction onto the photoreceptor 41. The control unit 10 proceeds to step S12.

[0064] In step S12, the control unit 10 instructs the cleaning unit 471 to clean the toner on the photoreceptor 41. The control unit 10 proceeds to step S13.

[0065] In step S13, the control unit 10 causes the measurement unit 11 to measure the physical quantities of the photoreceptor 41 and the blade a1 during the cleaning operation. The control unit 10 proceeds to step S14.

[0066] In step S14, the control unit 10 reads out the measurement values obtained by the measurement unit 11 and proceeds to step S15.

[0067] In step S15, the control unit 10 determines whether the obtained measurement values deviate from the threshold value. If they deviate from the threshold value (S15: YES), the control unit 10 determines that coating unevenness has occurred and there may be a cleaning defect, and proceeds to step S16. If they do not deviate from the threshold value (S15: NO), the control unit 10 determines that coating unevenness has not occurred and no cleaning defect has occurred. Then, the operation is terminated.

[0068] In step S15, the control unit 10 performs the following lubricant recovery process on the photoreceptor 41 and terminates the operation.

[0069] During the cleaning operation of the photoreceptor 41 to which the toner patch is supplied, the physical quantities of the photoreceptor 41 and the blade a1 vary greatly depending on the presence or absence of toner and the coating amount of the lubricant. The lubricant is applied to the surface of the photoreceptor 41, thereby increasing the friction coefficient of the photoreceptor 41. Therefore, in the region on the photoreceptor 41 where the coating amount of the lubricant is large, the friction coefficient of the photoreceptor 41 is large, and the force acting on the photoreceptor 41 and the blade a1 becomes large. When toner is supplied to the region where the coating amount of the lubricant is large, the toner acts on the photoreceptor 41 and the blade a1 respectively, and the change in the physical quantity in the photoreceptor 41 and the blade a1 becomes relatively large.

[0070] Conversely, in the region on the photoreceptor 41 where the coating amount of the lubricant is small, the friction coefficient of the photoreceptor 41 is small. Therefore, even when toner is supplied to the region where the coating amount of the lubricant is small, the change in the physical quantity in the photoreceptor 41 and the blade a1 is relatively small.

[0071] Since the interval of the stripe pattern of the toner patch is the same as the interval of the coating unevenness, toner is simultaneously supplied to a plurality of regions where the coating amount of the lubricant is large or small. As a result, when toner is simultaneously supplied to the region where the coating amount of the lubricant is large, the physical quantity in the photoreceptor 41 and the blade a1 becomes very large. Conversely, even when toner is simultaneously supplied to the region where the coating amount of the lubricant is small, the physical quantity in the photoreceptor 41 and the blade a1 is relatively small.

[0072] The stripe pattern of the toner patch is oblique in the main scanning direction. The measuring unit 11 measures the time change of the physical quantity in the photoreceptor 41 and the blade a1. Thereby, toner is supplied at a certain period to the region where the coating amount of the lubricant is large or small without accurately specifying the position of the coating unevenness in the main scanning direction.

[0073] Since the interval of coating unevenness varies depending on the material, thickness, installation angle of blade a1, installation environment of the device, etc., it is difficult to accurately grasp. Therefore, as shown in FIG. 9, it is preferable to use a plurality of toner patches with different intervals. When using a plurality of toner patches and the measured value obtained by any one of them exceeds the threshold value, it can be determined that coating unevenness has occurred. Note that the coverages of a plurality of toner patches with different intervals are set to the same value.

[0074] As shown in FIG. 10, the toner patch may be divided into a plurality in the main scanning direction. In FIG. 10, the toner patch is divided into three in the main scanning direction and shifted in the sub-scanning direction for supply, and the temporal change of the physical quantity between the photoreceptor 41 and the blade a1 is measured. When the obtained measured value exceeds the threshold value, it can be determined that coating unevenness has occurred at the location where the toner patch is being supplied at that time. By increasing the number of divisions of the toner patch, the location where coating unevenness has occurred on the photoreceptor can be determined in detail.

[0075] The case of measuring the driving torque of the photoreceptor 41 with a torque sensor as the physical quantity will be described. FIG. 11 is a graph showing the measurement result of the driving torque of the photoreceptor 41 when there is coating unevenness on the photoreceptor 41. FIG. 12 is a graph showing the measurement result of the driving torque of the photoreceptor 41 when there is no coating unevenness on the photoreceptor 41.

[0076] As shown in FIG. 11, when there is coating unevenness on the photoreceptor 41, when toner is supplied to a region with a large amount of lubricant applied, the value of the driving torque increases. Then, when toner is supplied to a region with a small amount of lubricant applied, the value of the driving torque decreases. When the value of the driving torque is below the threshold value, it is determined that unevenness in the amount of lubricant applied has occurred, and the possibility of cleaning failure can be predicted. Note that, as shown in FIG. 12, when there is no coating unevenness on the photoreceptor 41, the value of the driving torque exceeds the threshold value and changes constantly.

[0077] The case of measuring the vibration of the holding member a2 with an acceleration sensor 111 as the physical quantity will be described. The position of blade a1 varies significantly depending on the presence or absence of toner and the amount of lubricant applied. For example, when toner is supplied to an area with a large amount of lubricant applied, blade a1 is drawn into the rotation direction of the photoreceptor 41. In an area where the amount of lubricant applied is small, even if toner is supplied, blade a1 is less likely to be drawn into the photoreceptor 41. As a result, the stick-slip motion of blade a1 increases, and vibrations occur in the holding member a2.

[0078] FIG. 13 is a graph showing the measurement results of the acceleration sensor 111 when there is uneven coating on the photoreceptor 41. As shown in FIG. 13, when there is uneven coating on the photoreceptor 41, when toner is supplied to an area with a large amount of lubricant applied, the absolute value of the output value of the acceleration sensor 111 increases. Then, when toner is supplied to an area with a small amount of lubricant applied, the absolute value of the output value decreases. When the output value exceeds the upper threshold value or falls below the lower threshold value, it is possible to predict the occurrence of unevenness in the amount of lubricant applied and the occurrence of cleaning failure.

[0079] The case of measuring the vibration of spring a3 with the permeability sensor 113 as a physical quantity will be described. The position of blade a1 varies significantly depending on the presence or absence of toner and the amount of lubricant applied. For example, when toner is supplied to an area with a large amount of lubricant applied, blade a1 is drawn into the rotation direction of the photoreceptor 41, and the distance between the magnetic body 112 and the permeability sensor 113 decreases. The smaller the distance between the magnetic body 112 and the permeability sensor 113, the larger the output value of the permeability sensor 113. In an area where the amount of lubricant applied is small, even if toner is supplied, blade a1 is less likely to be drawn into the photoreceptor 41, and the output value of the permeability sensor 113 decreases.

[0080] FIG. 14 is a graph showing the measurement results of the magnetic permeability sensor 113 when there is coating unevenness on the photoreceptor 41. As shown in FIG. 14, when there is coating unevenness on the photoreceptor 41, when toner is supplied to an area where the coating amount of the lubricant is large, the output value of the magnetic permeability sensor 113 increases. Thereafter, when toner is supplied to an area where the coating amount of the lubricant is small, the output value decreases. When the output value falls below the threshold value, it is determined that there is unevenness in the coating amount of the lubricant, and the possibility of occurrence of cleaning failure can be predicted.

[0081] 〔Lubricant recovery process〕 When it is determined by the control unit 10 that coating unevenness has occurred in the image forming apparatus 1 of the present embodiment, that is, when coating unevenness is detected, it is preferable to cause the control unit 10 to execute a recovery process for eliminating the unevenness in the coating amount in the lubricant application unit. Examples of methods for restoring the coating amount of the lubricant on the photoreceptor 41 include the following methods.

[0082] As an example of the recovery method, a method of increasing the coating amount of the lubricant on the photoreceptor 41 as a whole can be mentioned. In this method, since the coating amount of the lubricant increases as a whole, a sufficient amount of lubricant that does not cause cleaning failure is also applied to areas where the coating amount of the lubricant is relatively small. Specifically, the control unit 10 instructs the lubricant application unit 472 to increase the rotation speed of the rotary brush 47c.

[0083] As an example of the recovery method, a method of peeling off the lubricant on the photoreceptor 41 and newly applying the lubricant on the photoreceptor 41 can be mentioned. In this method, since the lubricant is reapplied, coating unevenness can be eliminated. Specifically, the control unit 10 instructs the image forming unit 4 of the image forming section to supply toner onto the photoreceptor 41 as a whole. The lubricant is removed from the photoreceptor 41 by rubbing the toner and the lubricant together. Then, the control unit 10 instructs the lubricant application unit 472 to reapply the lubricant.

[0084] As an example of a recovery method, when it is possible to detect in detail a location where coating unevenness has occurred on the photoreceptor 41, there is a method of removing the lubricant from areas with a large coating amount and applying the lubricant to areas with a small coating amount. With this method, the coating unevenness can be eliminated.

[0085] Specifically, the control unit 10 instructs the image forming unit of the image forming section 4 to partially supply toner onto the photoreceptor 41 as shown in FIG. 15. FIG. 15 is a diagram showing the relationship between the coefficient of friction at the longitudinal position (main scanning direction) of the photoreceptor 41 and the supplied toner patches. As shown in FIG. 15, when the longitudinal position of the photoreceptor 41 is taken as the horizontal axis, the coefficient of friction is represented by a waveform. Since the value of the coefficient of friction is proportional to the coating amount of the lubricant, when the longitudinal position of the photoreceptor 41 is taken as the horizontal axis, the coating amount of the lubricant is also represented by a waveform. Therefore, the supply amount of toner with respect to the longitudinal position on the photoreceptor 41 is set to an amount represented by a waveform in the same phase as the coating amount of the lubricant, and toner is supplied according to the coating amount of the lubricant. By rubbing the toner and the lubricant together, the lubricant is partially removed. Then, the control unit 10 instructs the lubricant application unit 472 to apply the lubricant to an area on the photoreceptor 41 where the coating amount of the lubricant is small, that is, an area where the coefficient of friction is relatively small.

[0086] 〔Lubricant Unevenness Detection Method〕 The lubricant unevenness detection method of the present embodiment is a lubricant unevenness detection method for an image forming apparatus 1 including an image forming section 4 having an image carrier 41 that carries a toner image, a lubricant application unit 472 that applies a lubricant to the image carrier, and a cleaning unit 471 that cleans the toner remaining on the surface of the image carrier 41 with a blade, and includes a toner patch supply step of supplying toner patches in a diagonal stripe pattern at equal intervals in the main scanning direction onto the image carrier 41, a measurement step of measuring physical quantities between the image carrier 41 and the blade a1 during the cleaning operation of the image carrier 41 on which the toner patches are formed, and a determination step of determining the presence or absence of unevenness in the coating amount of the lubricant in the main scanning direction on the image carrier based on the measurement value measured in the measurement step.

[0087] 〔Program〕 The program of this embodiment causes a computer of an image forming apparatus including an image forming unit having an image carrier that carries a toner image, a lubricant application unit that applies a lubricant to the image carrier, and a cleaning unit that cleans toner remaining on the surface of the image carrier with a blade, to execute a toner patch supply process of supplying toner patches in a diagonal stripe pattern at equal intervals in the main scanning direction on the image carrier, a measurement process of measuring physical quantities of the image carrier and the blade during a cleaning operation of the image carrier on which the toner patches are formed, and a determination process of determining whether there is unevenness in the application amount of the lubricant in the main scanning direction on the image carrier based on the measurement values measured by the measurement process.

[0088] The computer-readable medium for storing the program is not particularly limited, and a portable recording medium may be applied. Further, a carrier wave may be applied as a medium for providing program data via a communication line.

[0089] In this embodiment, in an image forming apparatus 1 including an image forming unit 4 having an image carrier 41 that carries a toner image, a lubricant application unit 472 that applies a lubricant to the image carrier 41, and a cleaning unit 471 that cleans toner remaining on the surface of the image carrier 41 with a blade a1, a toner patch supply unit (control unit 10) that supplies toner patches in a diagonal stripe pattern at equal intervals in the main scanning direction on the image carrier 41, a measurement unit 11 that measures physical quantities of the image carrier 41 and the blade a1 during a cleaning operation of the image carrier 41 on which the toner patches are formed, and a determination unit (control unit 10) that determines whether there is unevenness in the application amount of the lubricant in the main scanning direction on the image carrier 41 based on the measurement values measured by the measurement unit 11 are provided. Thereby, unevenness in the application amount of the lubricant generated in the main scanning direction on the image carrier 41 can be suitably detected.

[0090] In this embodiment, the measurement unit 11 includes a torque sensor that measures the driving torque of the image carrier 41 as a physical quantity. Thereby, unevenness in the application amount of the lubricant generated in the main scanning direction on the image carrier 41 can be suitably detected.

[0091] In this embodiment, the measurement unit 11 includes a sensor that directly or indirectly measures the vibration of the blade a1 as a physical quantity. Thereby, unevenness in the coating amount of the lubricant generated in the main scanning direction on the image carrier 41 can be suitably detected.

[0092] In this embodiment, the cleaning unit 471 includes a holding member a2 that holds the blade a1, and the measurement unit 11 includes an acceleration sensor 111 that measures the vibration of the holding member a2 as a physical quantity. Thereby, unevenness in the coating amount of the lubricant generated in the main scanning direction on the image carrier 41 can be suitably detected.

[0093] In this embodiment, the cleaning unit 471 holds the blade a1 via a spring a3, and the measurement unit 11 includes a permeability sensor 113 that measures the vibration of the spring a3 as a physical quantity. Thereby, unevenness in the coating amount of the lubricant generated in the main scanning direction on the image carrier 41 can be suitably detected.

[0094] In this embodiment, the toner patch supply unit (control unit 10) supplies toner patches by dividing them in the main scanning direction. Thereby, it is possible to detect a location where unevenness in the coating amount of the lubricant on the image carrier 41 occurs.

[0095] In this embodiment, the toner patch supply unit (control unit 10) supplies a plurality of toner patches with different intervals. Thereby, even when it is not possible to grasp the interval of the unevenness in the coating amount of the lubricant on the image carrier 41, the unevenness in the coating amount can be detected.

[0096] In this embodiment, when it is determined by the determination unit (control unit 10) that unevenness in the coating amount of the lubricant has occurred, the control unit 10 is provided that causes the lubricant application unit 472 to execute a recovery process for eliminating the unevenness in the coating amount. Thereby, the coating amount of the lubricant on the image carrier 41 can be recovered.

[0097] In this embodiment, the control unit 10 causes the lubricant application unit 472 to execute a recovery process for increasing the coating amount of the lubricant on the image carrier 41. Thereby, the coating amount of the lubricant on the image carrier 41 can be recovered.

[0098] In this embodiment, the lubricant application unit 472 includes a rotary brush 47c that contacts the image carrier 41 to apply a lubricant, and the control unit 10 executes a recovery process for increasing the rotation speed of the rotary brush 47c. Thereby, the application amount of the lubricant on the image carrier 41 can be recovered.

[0099] In this embodiment, the control unit 10 causes the image forming unit 4 to supply toner onto the image carrier 41 to peel off the lubricant on the image carrier 41, and then causes the lubricant application unit 472 to execute a recovery process for newly applying the lubricant to the image carrier 41. Thereby, the application amount of the lubricant on the image carrier 41 can be recovered.

[0100] In this embodiment, the control unit 10 executes a recovery process for removing the lubricant in the region where the application amount of the lubricant on the image carrier 41 is large and applying the lubricant in the region where the application amount of the lubricant is small to the lubricant application unit 472. Thereby, the application amount of the lubricant on the image carrier 41 can be recovered.

[0101] In this embodiment, the control unit 10 causes the image forming unit 4 to supply toner onto the image carrier 41, and executes a recovery process for removing the lubricant by making the application amount of the lubricant with respect to the longitudinal position on the image carrier 41 and the supply amount of the toner with respect to the longitudinal position on the image carrier in the same phase. Thereby, the application amount of the lubricant on the image carrier 41 can be recovered.

[0102] In addition, regarding the detailed configuration and detailed operation of each device constituting the image forming apparatus, it can be appropriately changed within a range not departing from the spirit of the present invention.

Example

[0103] An image forming apparatus "Accurio (registered trademark) Press C14000" (manufactured by Konica Minolta, Inc.) was prepared, and a torque sensor was attached to the photoreceptor. The contact angle of the blade portion was set as the upper limit value. Using the said image forming apparatus, a severe durability test (double-sided continuous printing) with a low coverage was implemented. Then, in Examples 1-3, a toner patch was supplied onto the photoreceptor, and the time change of the driving torque of the photoreceptor during the cleaning operation was measured.

[0104] As shown in Table I, the image forming conditions and the type of blade material were changed during the severe durability test, and then the time change of the driving torque of the photoreceptor was measured. The image forming conditions in this test were conditions that would surely cause coating unevenness on the photoreceptor. In Table I, "-" indicates that it was not carried out.

[0105]

Table 1

[0106] In the "Full solid" of the image forming conditions, a white solid image was formed on the entire surface of the paper. As a result, equally spaced coating unevenness occurred throughout the main scanning direction of the photoreceptor. In "Partial solid", the paper was divided into three parts in the main scanning direction, and a white solid image was formed only in the central part. As a result, equally spaced coating unevenness occurred only in the central part where the photoreceptor was divided into three parts in the main scanning direction. As the cleaning blade, Blades A and B made of different materials were used.

[0107] In the comparative example, the image forming condition was full solid and Blade A was used. The time change of the driving torque of the photoreceptor was not measured. Then, when a halftone image was formed on the entire surface of the paper, white vertical streaks were confirmed on the halftone image.

[0108] In Example 1, similar to the comparative example, the image forming condition was full solid and Blade A was used. As the toner patch, a toner patch shown in FIG. 5 with a stripe pattern interval of 6.0 mm was used. When the time change of the driving torque of the photoreceptor during the cleaning operation was measured, it fell below the threshold value at a certain time, and coating unevenness of the photoreceptor was detected. As a lubricant recovery process, the rotation speed of the rotary brush was increased to increase the overall coating amount of the lubricant on the photoreceptor. Then, when a halftone image was formed on the entire surface of the paper, no white vertical streaks were confirmed on the halftone image.

[0109] In Example 2, the image forming conditions were partially solid, and Blade A was used. As the toner patch, a toner patch shown in FIG. 10 with a stripe pattern interval of 6.0 mm and divided into three parts in the main scanning direction was used. When measuring the time change of the driving torque of the photoreceptor during the cleaning operation, it was found that the threshold was exceeded at a certain time, and uneven coating of the photoreceptor was detected. In addition, it was detected that uneven coating occurred in the central part divided into three parts in the main scanning direction from the time when the threshold was exceeded. As a lubricant recovery process, after supplying toner to the central part on the photoreceptor to remove the lubricant, the lubricant was reapplied to the central part on the photoreceptor. Thereafter, when a halftone image was formed on the entire sheet of paper, no white vertical streaks were confirmed on the halftone image.

[0110] In Example 3, as in the comparative example, the image forming conditions were fully solid, and Blade B was used. As the toner patch, a plurality of toner patches shown in FIG. 9 with stripe pattern intervals of 6.0 mm, 6.2 mm, and 6.4 mm respectively were supplied. When measuring the time change of the driving torque of the photoreceptor during the cleaning operation, it was found that the threshold was exceeded at a certain time when the toner patch with a stripe pattern interval of 6.2 mm was supplied, and uneven coating of the photoreceptor was detected. As a lubricant recovery process, toner was supplied onto the photoreceptor so that the supply amount had a waveform in phase with the waveform of the coating unevenness, and part of the lubricant was removed. In addition, lubricant was applied to the areas on the photoreceptor where the coating amount of the lubricant was small. Thereafter, when a halftone image was formed on the entire sheet of paper, no white vertical streaks were confirmed on the halftone image.

[0111] From Examples 1 to 3, it can be seen that the image forming apparatus of the present embodiment can detect uneven coating amounts of the lubricant generated in the main scanning direction. In addition, it can be understood that the image forming apparatus of the present embodiment can prevent the occurrence of vertical streaks by performing the lubricant recovery process.

Explanation of Reference Numerals

[0112] 1 Image forming apparatus 2 Automatic document feeder 3 Scanner unit 4 Image forming unit 41 Photoreceptor 42 Charging device 43 Exposure device 44 Developing device 45 Primary transfer roller 46 Secondary transfer roller 471 Cleaning section 472 Lubricant application section 47a Blade section 47b Recovery screw a1 Blade a2 Holding member a3 Spring T Intermediate transfer belt 5 Sheet feeding section 6 Memory section 7 Operation display section 8 Communication section 10 Control section 11 Measuring section 20 Toner patch

Claims

1. An image forming apparatus including an image carrier that carries a toner image, a lubricant application unit that applies a lubricant to the image carrier, and a cleaning unit that cleans toner remaining on the surface of the image carrier with a blade, wherein the image carrier is provided with a toner patch supply unit that supplies toner patches having an oblique stripe pattern at equal intervals in the main scanning direction, a measurement unit that measures physical quantities of the image carrier and the blade during a cleaning operation of the image carrier on which the toner patches are formed, and a determination unit that determines whether there is unevenness in the application amount of the lubricant in the main scanning direction on the image carrier based on the measurement value measured by the measurement unit.

2. The image forming apparatus according to claim 1, wherein the measurement unit includes a torque sensor that measures a driving torque of the image carrier as the physical quantity.

3. The image forming apparatus according to claim 1, wherein the measurement unit includes a sensor that directly or indirectly measures vibration of the blade as the physical quantity.

4. The cleaning unit includes a holding member that holds the blade, and the image forming apparatus according to claim 3, wherein the measurement unit includes an acceleration sensor that measures vibration of the holding member as the physical quantity.

5. The cleaning unit holds the blade via a spring, and the image forming apparatus according to claim 3, wherein the measurement unit includes a permeability sensor that measures vibration of the spring as the physical quantity.

6. The image forming apparatus according to claim 1, wherein the toner patch supply unit supplies the toner patches by dividing them in the main scanning direction.

7. The image forming apparatus according to claim 1, wherein the toner patch supply unit supplies a plurality of toner patches having different intervals.

8. The image forming apparatus according to claim 1, further including a control unit that, when the determination unit determines that unevenness in the application amount of the lubricant has occurred, executes a recovery process for eliminating the unevenness in the application amount in the lubricant application unit.

9. The image forming apparatus according to claim 8, wherein the control unit executes a recovery process for increasing the application amount of the lubricant on the image carrier in the lubricant application unit.

10. The lubricant application unit includes a rotating brush that contacts the image carrier and applies the lubricant, and the image forming apparatus according to claim 9, wherein the control unit executes a recovery process for increasing the rotation speed of the rotating brush.

11. The image forming apparatus according to claim 8, wherein the control unit causes the image forming unit to supply toner onto the image carrier to peel off the lubricant on the image carrier, and then causes the lubricant application unit to perform a recovery process of newly applying the lubricant to the image carrier.

12. The image forming apparatus according to claim 8, wherein the control unit removes the lubricant in an area where the application amount of the lubricant on the image carrier is large, and causes the lubricant application unit to perform a recovery process of applying the lubricant in an area where the application amount of the lubricant is small.

13. The image forming apparatus according to claim 12, wherein the control unit causes the image forming unit to supply toner onto the image carrier, and by making the application amount of the lubricant with respect to the longitudinal position on the image carrier and the supply amount of toner with respect to the longitudinal position on the image carrier in the same phase, performs a recovery process of removing the lubricant.

14. A method for detecting unevenness of lubricant in an image forming apparatus including an image forming unit having an image carrier that carries a toner image, a lubricant application unit that applies a lubricant to the image carrier, and a cleaning unit that cleans toner remaining on the surface of the image carrier with a blade, comprising: a toner patch supply step of supplying toner patches having an oblique stripe pattern at equal intervals in the main scanning direction onto the image carrier; a measurement step of measuring physical quantities of the image carrier and the blade during a cleaning operation of the image carrier on which the toner patches are formed; a determination step of determining the presence or absence of unevenness in the application amount of the lubricant in the main scanning direction on the image carrier based on the measurement value measured in the measurement step.

15. A program for causing a computer of an image forming apparatus including an image forming unit having an image carrier that carries a toner image, a lubricant application unit that applies a lubricant to the image carrier, and a cleaning unit that cleans toner remaining on the surface of the image carrier with a blade to perform: a toner patch supply process of supplying toner patches having an oblique stripe pattern at equal intervals in the main scanning direction onto the image carrier; a measurement process of measuring physical quantities of the image carrier and the blade during a cleaning operation of the image carrier on which the toner patches are formed; a determination process of determining the presence or absence of unevenness in the application amount of the lubricant in the main scanning direction on the image carrier based on the measurement value measured in the measurement process.

Images