Image forming apparatus, image forming method, and image forming program

Abstract

To prevent the occurrence of tuck under.SOLUTION: An image forming apparatus forms an image according to a print job, and the image forming apparatus comprises: cleaning units that are each in contact with an image carrier and remove a toner remaining on the image carrier; a user identification unit 51 that identifies a user who instructs execution of the print job; and a feature amount acquisition unit 61 that determines whether to execute reduction control of reducing a frictional force generated between the cleaning unit and the image carrier on the basis of a feature amount specific to the user who instructs the execution of the print job.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus, an image forming method, and an image forming program, and more particularly to an image forming apparatus that forms an image using toner, an image forming method executed by the image forming apparatus, and an image forming program that causes a computer to execute the image forming method. [Background technology]

[0002] An image forming device forms an electrostatic latent image on a uniformly charged image carrier, develops the electrostatic latent image with toner to form a toner image, and transfers the toner image to paper. There are cases where not all of the toner image formed on the image carrier is transferred to paper. A cleaning blade is used to remove toner remaining on the image carrier by friction. As the cleaning blade wears, a phenomenon known as tack-under, in which toner slips through, becomes more likely to occur, which can lead to defects such as vertical stripes appearing in the image.

[0003] In the past, in order to suppress tack-under, efforts have been made to improve the uniformity of the cleaning blade in the longitudinal direction of the member that comes into contact with the image carrier, but it has not been possible to reliably suppress the occurrence of tack-under. The applicant has not found any prior art literature that suppresses the occurrence of tack-under. Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide an image forming apparatus capable of suppressing the occurrence of tuck-under.

[0005] Another object of the present invention is to provide an image forming method capable of suppressing the occurrence of tack-under.

[0006] It is still another object of the present invention to provide an image forming program that can suppress the occurrence of tuck-under. [Means for solving the problem]

[0007] According to one aspect of the present invention, an image forming apparatus is an image forming apparatus that forms an image in accordance with a print job, and includes a cleaning unit that contacts an image carrier and removes toner remaining on the image carrier, a user identification unit that identifies a user who instructed the execution of the print job, and a decision unit that decides whether to perform reduction control to reduce the frictional force generated between the cleaning unit and the image carrier based on characteristics unique to the user who instructed the execution of the print job.

[0008] According to another aspect of the present invention, an image forming apparatus is an image forming apparatus that forms an image in accordance with a print job, and includes a cleaning unit that contacts an image carrier and removes toner remaining on the image carrier, and a decision unit that decides whether to perform reduction control to reduce the frictional force generated between the cleaning unit and the image carrier based on historical information of the image forming operation.

[0009] According to yet another aspect of the present invention, an image forming method is an image forming method executed by an image forming device that forms an image in accordance with a print job, the image forming device having a cleaning unit that contacts an image carrier and removes toner remaining on the image carrier, and includes a user identification step that identifies a user who instructed the execution of the print job, and a decision step that decides whether to execute reduction control to reduce the frictional force generated between the cleaning unit and the image carrier based on characteristics unique to the user who instructed the execution of the print job.

[0010] According to yet another aspect of the present invention, an image forming method is an image forming method executed by an image forming device that forms an image in accordance with a print job, the image forming device having a cleaning unit that contacts an image carrier and removes toner remaining on the image carrier, and includes a decision step that decides whether to perform reduction control to reduce the frictional force generated between the cleaning unit and the image carrier based on historical information of image formation operations by the image forming device.

[0011] According to yet another aspect of the present invention, an image forming program causes a computer to execute the image forming method described above. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view schematically showing an example of the internal configuration of an MFP according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram schematically illustrating an internal configuration of the cleaning device. [Figure 3] FIG. 2 is a perspective view illustrating a contact state between a cleaning blade and a photosensitive drum. [Figure 4] 5A and 5B are diagrams illustrating an example of a contact state between a cleaning blade and a photosensitive drum. [Figure 5] 1 is a photograph of the edge of a cleaning blade when tack-under occurs. [Figure 6] This is a photoelastic image taken simultaneously with the micrograph in Figure 5. [Figure 7] 1 is a photograph of the edge of a cleaning blade when no tuck-under occurs. [Figure 8] This is a photoelastic image taken simultaneously with the micrograph in Figure 7. [Figure 9] FIG. 10 is a diagram showing an example of the relationship between the frictional force acting on the cleaning blade and the retraction amount. [Figure 10] FIG. 2 is a block diagram showing an outline of the hardware configuration of an MFP. [Figure 11] FIG. 2 is a diagram illustrating an example of functions of a CPU included in the MFP. [Figure 12] 10 is a flowchart illustrating an example of the flow of an image forming process. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same components are designated by the same reference numerals. The names and functions of these components are also the same. Therefore, detailed description thereof will not be repeated.

[0014] FIG. 1 is a cross-sectional view schematically illustrating an example of the internal configuration of an MFP according to an embodiment of the present invention. Referring to FIG. 1, an MFP (Multi Function Peripheral) 100 is an example of an image forming apparatus. In FIG. 1, an X direction, a Y direction, and a Z direction are defined, which are orthogonal to each other. The X direction and the Y direction are parallel to a horizontal plane. In the following description, the X direction is parallel to the left and right of the MFP 100 and is also referred to as the left-right direction. The positive side of the X direction is the right side, and the negative side of the X direction is the left side. The Y direction is parallel to the depth direction of the MFP 100 and is also referred to as the front-rear direction. The negative side of the Y direction is the front direction, and the positive side of the Y direction is the rear direction. The Z direction is parallel to the top-bottom direction of the MFP 100 and is also referred to as the up-down direction. The positive side of the Z direction is the up direction, and the negative side of the Z direction is the down direction.

[0015] MFP100 includes an original reading unit 130 that reads an original, an image forming unit 140 that forms an image on paper based on image data, and a paper feed unit 150 that supplies paper to image forming unit 140. Original reading unit 130 optically reads the image formed on the original, performs photoelectric conversion, and outputs image data as electronic data. Original reading unit 130 is equipped with a CCD (Charge Coupled Device) as a photoelectric conversion element. Original reading unit 130 converts the image data into printing data in cyan (C), magenta (M), yellow (Y), and black (K), and outputs the data to image forming unit 140.

[0016] The image forming unit 140 includes image forming units 20C, 20M, 20Y, and 20K for cyan, magenta, yellow, and black, respectively. Here, "C," "M," "Y," and "K" represent cyan, magenta, yellow, and black, respectively. An image is formed by driving at least one of the image forming units 20C, 20M, 20Y, and 20K. A full-color image is formed by driving all of the image forming units 20C, 20M, 20Y, and 20K. Printing data for cyan, magenta, yellow, and black are input to the image forming units 20C, 20M, 20Y, and 20K, respectively. The image forming units 20C, 20M, 20Y, and 20K differ only in the color of the toner they use. Therefore, the image forming unit 20C for forming a cyan image will be described here.

[0017] Image forming unit 20C includes an exposure device 21, a photosensitive drum 23 serving as an image carrier, a charging roller 22, a developing device 24, a primary transfer roller 25, and a cleaning device 27. The charging roller 22 uniformly charges the surface of the photosensitive drum 23. Cyan printing data is input to the exposure device 21, which forms an electrostatic latent image on the surface of the photosensitive drum 23 by irradiating the photosensitive drum 23 with laser light. The developing device 24 develops the electrostatic latent image formed on the photosensitive drum 23. The primary transfer roller 25 transfers the toner image formed on the photosensitive drum 23 onto an intermediate transfer belt 30 serving as an image carrier by the action of an electric field. The cleaning device 27 removes any toner remaining on the photosensitive drum 23.

[0018] Around the photosensitive drum 23, a charging roller 22, an exposure device 21, a developing device 24, a primary transfer roller 25, and a cleaning device 27 are arranged in this order along the direction of rotation of the photosensitive drum 23.

[0019] After being charged by the charging roller 22, the photosensitive drum 23 is irradiated with laser light emitted by the exposure device 21. The exposure device 21 exposes the image-corresponding portion of the surface of the photosensitive drum 23 to light. This forms an electrostatic latent image on the photosensitive drum 23. Next, the developing device 24 develops the electrostatic latent image formed on the photosensitive drum 23 with charged toner. Specifically, toner is placed on the electrostatic latent image formed on the photosensitive drum 23 by the action of an electric field, thereby forming a toner image on the photosensitive drum 23. The toner image formed on the photosensitive drum 23 is transferred onto the intermediate transfer belt 30, which serves as an image carrier, by the action of an electric field using the primary transfer roller 25. Any toner remaining on the photosensitive drum 23 that has not been transferred is removed from the photosensitive drum 23 by the cleaning device 27.

[0020] Meanwhile, the intermediate transfer belt 30 is suspended tightly by a drive roller 33 and driven rollers 34 and 35. When the drive roller 33 rotates clockwise in FIG. 1, the intermediate transfer belt 30 rotates clockwise in the drawing at a predetermined speed. As the intermediate transfer belt 30 rotates, the driven rollers 34 and 35 also rotate clockwise.

[0021] As a result, the image forming units 20C, 20M, 20Y, and 20K sequentially transfer toner images onto the intermediate transfer belt 30. The timing at which each of the image forming units 20C, 20M, 20Y, and 20K transfers a toner image onto the intermediate transfer belt 30 is adjusted based on the detection of the reference marks on the intermediate transfer belt 30. As a result, cyan, magenta, yellow, and black toner images are superimposed on the intermediate transfer belt 30.

[0022] The toner image formed on the intermediate transfer belt 30 is transferred to paper by the action of electric field force by the secondary transfer roller 26, which is a transfer member. The paper is transported by timing roller 31 to the nip portion where the intermediate transfer belt 30 and secondary transfer roller 26 come into contact. The paper with the transferred toner image is transported to fixing roller 32, where it is heated and pressed. This melts the toner and fixes it to the paper. The paper is then ejected to paper output tray 39.

[0023] A belt cleaning blade 28 is provided upstream of the image forming unit 20Y on the intermediate transfer belt 30. The belt cleaning blade 28 removes toner remaining on the intermediate transfer belt 30 that has not been transferred to paper.

[0024] Paper sheets are set in paper feed cassettes 38. The paper sheets stored in paper feed cassettes 38 are supplied to the transport path by take-out rollers 36 attached to each paper feed cassette 38, and sent to timing rollers 31 by paper feed rollers 37.

[0025] When forming a full-color image, the MFP 100 drives all of the image forming units 20C, 20M, 20Y, and 20K. When forming a monochrome image, the MFP 100 drives only one of the image forming units 20C, 20M, 20Y, and 20K. It is also possible to form an image by combining two or more of the image forming units 20C, 20M, 20Y, and 20K. Here, we will explain an example in which the MFP 100 employs a tandem system equipped with image forming units 20C, 20M, 20Y, and 20K that form four color toners on paper. However, a four-cycle system in which four color toners are transferred sequentially onto paper using a single photosensitive drum may also be employed.

[0026] FIG. 2 is a diagram schematically illustrating the internal configuration of the cleaning device. Referring to FIG. 2, the cleaning device 27 includes a cleaning blade 41, a holder 43, a collection brush 45, a collection roller 47, and a collection screw 49. The collection brush 45 is formed, for example, by wrapping a cloth made of looped polyester fibers around a metal shaft. The collection brush 45 rotates in the opposite direction to the rotation direction of the photosensitive drum 23. The peripheral speed of the collection brush 45 is slower than the peripheral speed of the photosensitive drum 23. The collection brush 45 collects toner remaining on the surface of the photosensitive drum 23 after the toner image has been transferred by the primary transfer roller 25.

[0027] The collection roller 47 is a roller made of metal such as stainless steel. The collection roller 47 rotates in the opposite direction to the rotation direction of the collection brush 45. The toner collected by the collection brush 45 from the photosensitive drum 23 is transported to the collection roller 47 by the rotation of the collection brush 45. A stainless steel plate abuts against the collection roller 47. The collection roller 47 scrapes the toner collected by the collection brush 45 off the collection brush 45.

[0028] The toner removed from the collection brush 45 by the collection roller 47 falls onto the collection screw 49. The collection screw 49 has a spiral blade. The collection screw 49 collects the toner that has fallen from the collection brush 45 and discharges it into a waste toner box.

[0029] The cleaning blade 41 is elastic and has a flat plate shape that is long in one direction. The cleaning blade 41 is formed by molding an elastomer such as polyurethane rubber into a strip shape. The holding portion 43 is a flat metal plate. The cleaning blade 41 is attached to the holding portion 43 with an adhesive or the like. The cleaning blade 41 is held by the holding portion 43 at a position where its tip abuts against the photosensitive drum 23. The holding portion 43 is fixed to the housing of the MFP 100. The cleaning blade 41 removes toner remaining on the photosensitive drum 23 by frictional force.

[0030] Since the cleaning blade 41 contacts the photosensitive drum 23, a phenomenon called tuck-under may occur in which the cleaning blade 41 is pulled in locally and significantly in the longitudinal direction as the photosensitive drum 23 rotates.

[0031] 3 is a perspective view illustrating the contact state between the cleaning blade and the photosensitive drum. The cleaning blade 41 is held by a holding portion 43 while in contact with the photosensitive drum 23. The length L of the cleaning blade 41 in the longitudinal direction is equal to or greater than the width of the photosensitive drum 23. One of the shorter sides of the cleaning blade 41 is held in a cantilevered state by the holding portion 43. The end of the cleaning blade 41 that is not held by the holding portion 43 is the edge. The cleaning blade 41 is held in a cantilevered state by the holding portion 43 while the edge is in contact with the photosensitive drum 23.

[0032] 4 is a diagram schematically illustrating an example of a contact state between the cleaning blade and the photosensitive drum. Referring to FIG. 4, cleaning blade 41 is held by holding portion 43 so that its edge contacts photosensitive drum 23 in an elastically deformed state. Therefore, the edge of cleaning blade 41 is pressed against photosensitive drum 23 by an elastic force generated by the elastic deformation. Furthermore, the edge of cleaning blade 41 contacts photosensitive drum 23 so that the angle θ formed between the edge of cleaning blade 41 and photosensitive drum 23 is constant in the longitudinal direction of cleaning blade 41.

[0033] The cleaning blade 41 may experience a phenomenon called tuck-under, in which a large localized pull occurs in the longitudinal direction. When the cleaning blade 41 experiences tuck-under, toner slips through the gap between the cleaning blade 41 and the photosensitive drum 23. As a result, the toner adheres to the charging roller 22, which is located downstream of the cleaning blade 41 in the rotation direction of the photosensitive drum 23.

[0034] Because tack-under occurs locally in the longitudinal direction of the cleaning blade 41, toner also reaches the charging roller 22 locally. As a result, toner adheres to the charging roller 22 in a ring shape. The surface resistance of the toner-adhered portions of the charging roller 22 increases compared to portions where toner is not attached. As a result, the charge amount of the portions of the photosensitive drum 23 corresponding to the toner-adhered portions of the charging roller 22 decreases compared to other portions. A toner image is formed on the photosensitive drum 23 in the portions where the charge amount is reduced, resulting in streaky noise in the image formed on the paper. Therefore, it is desirable to prevent tack-under from occurring.

[0035] FIG. 5 is a photograph of the edge portion of the cleaning blade when tack-under has occurred. FIG. 6 is a photoelastic image taken simultaneously with the microscopic photograph of FIG. 5. The photograph shown in FIG. 5 is a microscopic photograph of the edge portion of the cleaning blade 41 taken from inside a cylindrical glass tube manufactured in place of the photosensitive drum 23, with the cleaning blade 41 in contact with the glass tube. The horizontal direction in FIG. 5 is the longitudinal direction of the cleaning blade 41. Referring to FIG. 6, it can be seen that when tack-under has occurred, the internal stress around the edge portion of the cleaning blade 41 is non-uniform.

[0036] Fig. 7 is a photograph of the edge portion of the cleaning blade when tuck-under does not occur. Fig. 8 is a photoelastic image taken simultaneously with the microscopic photograph of Fig. 7. Referring to Fig. 8, it can be seen that when tuck-under does not occur, the internal stress around the edge portion of cleaning blade 41 is uniform.

[0037] 9 is a diagram showing an example of the relationship between the frictional force acting on the cleaning blade 41 and the retraction amount. The retraction amount of the cleaning blade 41 indicates the amount of deformation of the edge portion of the cleaning blade 41 in the circumferential direction of the photosensitive drum 23. In FIG. 9, the horizontal axis indicates the frictional force acting on the cleaning blade 41, and the vertical axis indicates the retraction amount of the cleaning blade 41.

[0038] The frictional force acting on the cleaning blade 41 was measured by placing a load cell between the cleaning blade 41 and the holding portion 43. The retraction amount of the cleaning blade 41 was measured by measuring the difference between when the glass tube was stationary and when it was moving. In Figure 9, the circles indicate measurements when no tuck-under occurred, and the crosses indicate measurements when tuck-under occurred. This shows that the retraction amount increases as the frictional force acting on the cleaning blade 41 increases. It is also clear that tuck-under occurs when the frictional force acting on the cleaning blade 41 exceeds a predetermined value. From these findings, it was discovered that reducing the frictional force acting on the edge portion of the cleaning blade 41 is an effective way to prevent tuck-under from occurring.

[0039] The reduction control for reducing the frictional force between the cleaning blade 41 and the photosensitive drum 23 is a control for forming an image at a low process speed that is slower than the normal process speed. The image formation process speed is the speed at which the image forming unit 140 forms an image on paper, and is equal to the circumferential speed at which the photosensitive drum 23 rotates. When the image forming unit 140 forms an image at the low process speed, the relative speed between the cleaning blade 41 and the photosensitive drum 23 is slower than when the image forming unit 140 forms an image at the normal process speed.

[0040] External additives that have fallen off from the toner are present as fine powder between the cleaning blade 41 and the photosensitive drum 23, and the fine powder acts as a roller. In this case, when the fine powder passes between the cleaning blade 41 and the photosensitive drum 23, the cleaning blade 41 deforms to a shape that corresponds to the outer shape of the fine powder.

[0041] Because the elastomer that makes up the cleaning blade 41 has viscosity, the amount of elastic deformation of the cleaning blade 41 increases as the relative speed between the cleaning blade 41 and the photosensitive drum 23 increases. This increases the reaction force generated in the cleaning blade 41. For this reason, the faster the relative speed between the cleaning blade 41 and the photosensitive drum 23, the greater the frictional force acting on the cleaning blade 41. Therefore, by making the relative speed between the cleaning blade 41 and the photosensitive drum 23 slower than the normal process speed, the frictional force between the cleaning blade 41 and the photosensitive drum 23 is reduced.

[0042] Fig. 10 is a block diagram showing an outline of the hardware configuration of an MFP. Referring to Fig. 10, MFP 100 is an example of an image forming apparatus, and includes a main circuit 110, a document reading unit 130, an image forming unit 140, a paper feeding unit 150, and an operation panel 160 as a user interface.

[0043] Main circuit 110 includes a CPU (Central Processing Unit) 111 that controls the entire MFP 100, a communication interface (I / F) unit 112, a ROM (Read Only Memory) 113, a RAM (Random Access Memory) 114, a hard disk drive (HDD) 115 as a large-capacity storage device, a facsimile unit 116, and an external storage device 118. CPU 111 is connected to document reading unit 130, image forming unit 140, paper feeding unit 150, and operation panel 160, and controls the entire MFP 100.

[0044] ROM 113 stores programs executed by CPU 111 or data required to execute the programs. RAM 114 is used as a work area when CPU 111 executes the programs. RAM 114 also temporarily stores image data continuously sent from document reading unit 130.

[0045] Operation panel 160 is provided on the top of MFP 100. Operation panel 160 includes display unit 161 and operation unit 163. Display unit 161 is, for example, a liquid crystal display (LCD), and displays an instruction menu for the user, information related to acquired image data, and the like. Note that instead of an LCD, any device that displays images, such as an organic EL (electroluminescence) display, can be used.

[0046] The operation unit 163 includes a touch panel 165 and a hard key unit 167. The touch panel 165 is of a capacitance type. Note that the touch panel 165 is not limited to a capacitance type, and other types such as a resistive film type, a surface acoustic wave type, an infrared type, or an electromagnetic induction type can be used. The touch panel 165 has a detection surface that is provided on the upper or lower surface of the display unit 161 and is superimposed on the display unit 161. The hard key unit 167 includes a plurality of hard keys.

[0047] The communication I / F unit 112 is an interface for connecting the MFP 100 to a network. The communication I / F unit 112 communicates with other computers or data processing devices connected to the network using a communication protocol such as TCP (Transmission Control Protocol) or FTP (File Transfer Protocol). The network to which the communication I / F unit 112 is connected is a local area network (LAN), and the connection type may be wired or wireless. The network is not limited to a LAN, and may be a wide area network (WAN), a public switched telephone network (PSTN), the Internet, or the like.

[0048] Facsimile unit 116 is connected to the public switched telephone network (PSTN) and transmits facsimile data to the PSTN or receives facsimile data from the PSTN. Facsimile unit 116 stores the received facsimile data in HDD 115, converts it into print data that can be printed by image forming unit 140, and outputs it to image forming unit 140. As a result, image forming unit 140 forms an image of the facsimile data received by facsimile unit 116 on paper. Facsimile unit 116 also converts the data stored in HDD 115 into facsimile data and transmits it to a facsimile device connected to the PSTN.

[0049] External storage device 118 is controlled by CPU 111, and is equipped with CD-ROM (Compact Disk Read Only Memory) 118A or a semiconductor memory. In this embodiment, an example will be described in which CPU 111 executes a program stored in ROM 113. CPU 111 may control external storage device 118 to read a program to be executed by CPU 111 from CD-ROM 118A, store the read program in RAM 114, and execute it.

[0050] The recording medium for storing the program executed by CPU 111 is not limited to CD-ROM 118A, but may be a flexible disk, cassette tape, optical disk, semiconductor memory, or other medium. Optical disks include magnetic optical discs (MOs), mini discs (MDs), and digital versatile discs (DVDs). Semiconductor memories include IC cards, optical cards, mask ROMs, and erasable programmable ROMs (EPROMs). Furthermore, CPU 111 may load a program stored in HDD 115 into RAM 114 and execute it. Programs stored in HDD 115 include programs downloaded by CPU 111 from a computer connected to the network and programs written to HDD 115 by a computer connected to the network. The program referred to here includes not only programs directly executable by CPU 111, but also source programs, compressed programs, encrypted programs, and the like.

[0051] Fig. 11 is a diagram showing an example of functions of a CPU included in an MFP. The functions shown in Fig. 11 are realized by CPU 111 included in MFP 100 as CPU 111 executes an image forming program stored in ROM 113, HDD 115, or CD-ROM 118A. Referring to Fig. 11, CPU 111 includes user identification unit 51, determination unit 53, image formation control unit 55, and history information storage unit 57.

[0052] User identification unit 51 identifies the user who instructed MFP 100 to execute a print job. A print job is input to MFP 100 from an external device. When a user operates a personal computer (PC) to specify image data and set printing conditions, the PC generates a print job. The PC transmits the print job to MFP 100. This print job includes identification information for identifying the user operating the PC. When communication I / F unit 112 receives a print job from the PC, CPU 111 executes the print job. User identification unit 51 identifies the user specified by the identification information included in the print job received by communication I / F unit 112 from the PC as the user who instructed the execution of the print job. User identification unit 51 outputs the identification information for identifying the user who instructed the execution of the print job to determination unit 53.

[0053] Image formation control unit 55 controls image forming unit 140 to form an image on paper. Every time image forming unit 140 forms an image, image formation control unit 55 outputs operation status information indicating the status of the image forming operation to history information storage unit 57. The operation status information includes the sliding distance of the photosensitive drum, the sliding distance of the developing roller, and the amount of toner supplied to photosensitive drum 23.

[0054] The photosensitive drum sliding distance is the distance the photosensitive drum 23 slides against the cleaning blade 41 in contact with it. The photosensitive drum sliding distance is calculated from the outer circumferential length and rotation speed of the photosensitive drum 23. The developing roller sliding distance is the distance the developing roller of the developing unit 24 slides against the photosensitive drum 23. The developing roller sliding distance is calculated from the outer circumferential length and rotation speed of the developing roller of the developing unit 24. The amount of toner supplied to the photosensitive drum 23 is calculated based on the image data included in the print job. The amount of toner for each of multiple colors is determined for the image data. Image data exists for cyan, magenta, yellow, and black. Therefore, the amount of toner supplied to the photosensitive drum 23 is calculated as the sum of the toner amounts determined for each color.

[0055] History information storage unit 57 generates operation history information from the operation status information and stores the operation history information in HDD 115. The operation history information includes the ratio between the amount of toner supplied to photosensitive drum 23 and the sliding distance of the photosensitive drum, and the ratio between the sliding distance of the developing roller and the sliding distance of the photosensitive drum.

[0056] The determination unit 53 determines whether or not to execute reduction control to reduce the frictional force generated between the cleaning blade 41 and the photosensitive drum 23. The determination unit 53 includes a feature amount acquisition unit 61 and a history information acquisition unit 63. The feature amount acquisition unit 61 receives identification information from the user identification unit 51. The feature amount acquisition unit 61 acquires a feature amount specific to the user identified by the identification information. The feature amount is the amount of spatial information required from when the user issues an instruction to execute a print job until the print job is executed and a printed matter on which an image is formed is obtained. The unit of the spatial information amount may be time or distance.

[0057] When the unit of spatial information amount is time, the feature amount acquisition unit 61 acquires the time required from when a user issues a print job command to when a printed matter is acquired. The feature amount acquisition unit 61 stores, for each user, usage history information on the time required from when a print command is issued to when a printed matter is acquired in the HDD 115. For example, the paper output tray 39 is provided with a paper detection sensor that detects paper. The feature amount acquisition unit 61 detects the time when paper is detected by the paper detection sensor and then becomes undetectable as the time when the printed matter is acquired. The feature amount acquisition unit 61 stores, in the HDD 115, usage history information including the time when the print job is received, the time when the printed matter is acquired, and identification information of the user who issued the command to execute the print job.

[0058] The feature acquisition unit 61 reads out from the HDD 115 the usage history information including the identification information input from the user identification unit 51 and performs statistical processing. The feature acquisition unit 61 calculates the average value u and variance σ of the time required from the print instruction included in the usage history information to the acquisition of the printed matter, and calculates u+3σ as the amount of spatial information of the user.

[0059] The feature amount acquisition unit 61 compares the user's spatial information amount with the predicted time required for the print job to be executed under reduced pressure control. The predicted time is the time required for the image forming unit 140 to form images on multiple sheets of paper at the image formation process speed (the slow process speed). The predicted time includes the number of sheets of paper on which images are to be formed in the print job. The feature amount acquisition unit 61 calculates the predicted time based on the number of sheets of paper on which images are to be formed in the print job and the slow process speed. If the spatial information amount is equal to or greater than the predicted time, the feature amount acquisition unit 61 determines to execute reduced pressure control. If the spatial information amount is less than the predicted time, the feature amount acquisition unit 61 determines not to execute reduced pressure control. Therefore, the print job is completed by the time the user issues a print job command and obtains the printed material, eliminating user waiting time and ensuring user convenience. Furthermore, when reduced pressure control is executed, the frictional force between the cleaning blade 41 and the photosensitive drum 23 is reduced, thereby suppressing tuck-under.

[0060] When the unit of the spatial information amount is distance, feature amount acquisition unit 61 reads out the first position information and the second position information from HDD 115. MFP 100 stores in HDD 115 the first position information indicating a first position where a PC operated by at least one user who is permitted to use MFP 100 is located, and the second position information specifying the second position where MFP 100 is located.

[0061] In response to input of identification information from the user identification unit 51, the feature acquisition unit 61 reads from the HDD 115 the first location information of the user identified by the identification information. The feature acquisition unit 61 calculates the distance between the first location identified by the first location information and the second location identified by the second location information as spatiotemporal information. As the distance, Manhattan distance and Euclidean distance can be used. Since the time taken by the user to travel is used, it is desirable to use Manhattan distance.

[0062] The feature amount acquisition unit 61 compares the amount of spatial information of the user with a predicted distance corresponding to the predicted time for which the print job will be executed under reduced control. The predicted distance is the distance the user will travel during the time it takes for the image forming unit 140 to form images on multiple sheets of paper at the image formation process speed (the slow process speed). The predicted distance includes the number of sheets of paper on which images will be formed in the print job. The feature amount acquisition unit 61 calculates the predicted time from the number of sheets of paper on which images will be formed in the print job and the slow process speed. Furthermore, the feature amount acquisition unit 61 calculates the predicted distance from the predicted time and the user's movement speed. The MFP 100 stores, in the HDD 115, the movement speed of at least one user authorized to use the MFP 100. If the amount of spatial information is equal to or greater than the predicted distance, the feature amount acquisition unit 61 determines to execute reduced control. If the amount of spatial information is less than the predicted distance, the feature amount acquisition unit 61 determines not to execute reduced control. Therefore, execution of the print job is completed by the time the user issues a command to execute the print job and obtains the printed material. This eliminates user waiting time, and user convenience is not impaired. Furthermore, when the reduction control is executed, the frictional force between the cleaning blade 41 and the photosensitive drum 23 decreases, so that the occurrence of tuck-under can be suppressed.

[0063] The history information acquisition unit 63 acquires operation history information stored in the HDD 115 and determines whether to execute the reduction control. The operation history information includes the ratio between the amount of toner supplied to the photosensitive drum 23 and the sliding distance of the photosensitive drum, and the ratio between the sliding distance of the developing roller and the sliding distance of the photosensitive drum. The history information acquisition unit 63 determines to execute the reduction control when at least one of the ratio between the amount of toner supplied to the photosensitive drum 23 and the sliding distance of the photosensitive drum or the ratio between the sliding distance of the developing roller and the sliding distance of the photosensitive drum satisfies a start condition. The history information acquisition unit 63 determines not to execute the reduction control when neither the ratio between the amount of toner supplied to the photosensitive drum 23 and the sliding distance of the photosensitive drum nor the ratio between the sliding distance of the developing roller and the sliding distance of the photosensitive drum satisfies the start condition. The start condition is a condition in which the amount of residual toner reaching the cleaning blade 41 is equal to or greater than a predetermined amount.

[0064] The ratio between the amount of toner supplied to the photosensitive drum 23 and the sliding distance of the photosensitive drum is a value obtained by dividing the amount of toner supplied to the photosensitive drum 23 by the sliding distance of the photosensitive drum. In this case, the start condition can be that the ratio between the amount of toner supplied to the photosensitive drum 23 and the sliding distance of the photosensitive drum is equal to or less than a first threshold value. The ratio between the sliding distance of the developing roller and the sliding distance of the photosensitive drum is a value obtained by dividing the sliding distance of the developing roller by the sliding distance of the photosensitive drum. In this case, the start condition can be that the ratio between the sliding distance of the developing roller and the sliding distance of the photosensitive drum is equal to or less than a second threshold value.

[0065] When it is determined in each of the feature amount acquiring section 61 and the history information acquiring section 63 that reduction control is to be executed, the determining section 53 outputs an execution instruction to the image forming control section 55 to execute reduction control.

[0066] When an execution instruction is input from the determination unit 53, the image formation control unit 55 controls the image forming unit 140 to form an image at a reduced process speed that is slower than the normal speed as the image process speed.

[0067] 12 is a flowchart showing an example of the flow of image formation processing. The image formation processing is performed by CPU 111 included in MFP 100 as CPU 111 executes an image formation program stored in ROM 113, HDD 115, or CD-ROM 118A. Referring to FIG. 12, CPU 111 determines whether a print job has been accepted (step S01). CPU 111 enters a standby state until communication I / F unit 112 accepts a print job from a PC (NO in step S01), and if the print job has been accepted (YES in step S01), the process proceeds to step S02.

[0068] In step S02, the user is identified, and the process proceeds to step S03. The user who instructed the execution of the print job is identified. CPU 111 identifies the user identified by the identification information included in the print job.

[0069] In step S03, operation history information is acquired, and the process proceeds to step S04. CPU 111 reads out the operation history information stored in HDD 115. The operation history information includes the ratio between the amount of toner supplied to photosensitive drum 23 and the sliding distance of the photosensitive drum, and the ratio between the sliding distance of the developing roller and the sliding distance of the photosensitive drum.

[0070] In step S04, it is determined whether the first condition is satisfied. CPU 111 compares the evaluation value calculated from the operation history information with a predetermined evaluation value. The evaluation value is calculated from the ratio of the amount of toner supplied to photoconductor drum 23 to the sliding distance of the photoconductor drum, and the ratio of the sliding distance of the developing roller to the sliding distance of the photoconductor drum. CPU 111 determines the evaluation value as a value obtained by dividing the amount of toner supplied to photoconductor drum 23 by the sliding distance of the photoconductor drum. CPU 111 determines the first condition is satisfied if the evaluation value is equal to or less than a first threshold value. Alternatively, CPU 111 may determine the value obtained by dividing the sliding distance of the developing roller by the sliding distance of the photoconductor drum. CPU 111 determines the first condition is satisfied if the evaluation value is equal to or less than a second threshold value. If the first condition is satisfied, the process proceeds to step S05. If not, the process proceeds to step S09.

[0071] In step S05, spatial information is acquired, and the process proceeds to step S06. Here, an example will be described in which the spatial information is time. The spatial information is a predicted time from when a user issues a print instruction to when the printed material is obtained. The spatial information is a value unique to the user identified in step S02. Specifically, CPU 111 statistically processes the usage history information associated with the user identified in step S02 from the usage history information stored in HDD 115. CPU 111 calculates the average value u and variance value σ of the time required from when a print instruction is issued to when the printed material is obtained, which is included in the usage history information, and calculates u + 3σ as the amount of spatial information for the user.

[0072] In step S07, it is determined whether the amount of spatial information satisfies the second condition. CPU 111 compares the amount of spatial information with the time required to execute the print job. CPU 111 calculates the time required for image forming unit 140 to execute the print job at the reduced image process speed as the time required to execute the print job. CPU 111 determines that the second condition is satisfied if the amount of spatial information is equal to or greater than the time required to execute the print job. If the second condition is satisfied, the process proceeds to step S07; otherwise, the process proceeds to step S08.

[0073] In step S07, the reduction control is set to ON, and the process proceeds to step S09. In step S08, the reduction control is set to OFF, and the process proceeds to step S09. In step S09, the print job accepted in step S01 is executed, and the process ends. If the process proceeds from step S08, CPU 111 controls image forming unit 140 to form an image at the normal process speed as the image process speed. If the process proceeds from step S07, CPU 111 controls image forming unit 140 to form an image at the reduced process speed as the image process speed. The reduced process speed is slower than the normal process speed. This reduces the frictional force generated between photosensitive drum 23 and cleaning blade 41, thereby suppressing the occurrence of tuck-under.

[0074] <First Modification> In the above-described embodiment, the decision unit 53 shown in Fig. 11 includes the feature amount acquisition unit 61 and the history information acquisition unit 63. When the feature amount acquisition unit 61 determines to perform reduction control and the history information acquisition unit 63 determines to perform reduction control, the decision unit 53 decides to execute reduction control.

[0075] Alternatively, after the history information acquisition unit 63 has determined that reduction control should be performed, the feature amount acquisition unit 61 may determine whether or not to perform reduction control. In this case, when the history information acquisition unit 63 has determined that reduction control should not be performed, the feature amount acquisition unit 61 does not need to determine whether or not to perform reduction control, thereby reducing the processing load.

[0076] Furthermore, after the feature amount acquisition unit 61 has determined that reduction control should be performed, the history information acquisition unit 63 may determine whether or not to perform reduction control. In this case, when the feature amount acquisition unit 61 has determined that reduction control should not be performed, the history information acquisition unit 63 does not need to determine whether or not to perform reduction control, which reduces the processing load.

[0077] <Second Modification> The determination unit 53 may include only one of the feature amount acquisition unit 61 and the history information acquisition unit 63. When the determination unit 53 includes the feature amount acquisition unit 61, the history information acquisition unit 63 and the history information storage unit 57 are unnecessary. Also, when the determination unit 53 includes the history information acquisition unit 63, the feature amount acquisition unit 61 and the user identification unit 51 are unnecessary.

[0078] <Third Modification> When the unit of the amount of spatial information is time, the feature amount acquiring section 61 may calculate the predicted time from the first position, the second position, and the moving speed of the user.

[0079] <Fourth Modification> In the above-described embodiment, the reduction control is control for forming an image at an image process speed that is a reduced process speed slower than the normal process speed. The reduction control of the present invention is not limited to this. If the MFP 100 includes an application unit that applies a lubricant to the cleaning blade 41, the reduction control may be control for driving the application unit to apply the lubricant to the cleaning blade 41. Since the lubricant is applied to the cleaning blade 41, the friction force between the cleaning blade 41 and the photosensitive drum 23 is reduced.

[0080] Furthermore, the reduction control may be a control for driving the image forming unit 140 to form a desired toner image on the photosensitive drum 23 while the photosensitive drum 23 is spaced from the intermediate transfer belt 30. When the toner image formed on the photosensitive drum 23 is removed by the cleaning blade 41, external additives contained in the toner that constitutes the toner image adhere to the cleaning blade 41. The external additives contain a lubricant, and therefore the frictional force between the cleaning blade 41 and the photosensitive drum 23 is reduced.

[0081] <Summary of implementation form> (Item 1) An image forming apparatus that forms an image according to a print job, a cleaning unit that comes into contact with the image carrier and removes toner remaining on the image carrier; a user identification unit for identifying a user who has instructed execution of the print job; and a decision unit that decides whether to perform reduction control to reduce the frictional force generated between the cleaning unit and the image carrier based on a characteristic amount unique to the user who instructed the execution of the print job.

[0082] According to this aspect, whether or not to execute reduction control to reduce the frictional force generated between the cleaning unit and the image carrier is determined based on the characteristic amount of the user who instructed the execution of the print job. Therefore, reduction control can be executed only when the characteristic amount of the user is a value that allows execution of reduction control. Therefore, the cleaning ability of the cleaning unit can be maintained without reducing user convenience. As a result, an image forming apparatus capable of suppressing the occurrence of tack-under can be provided.

[0083] (Item 2) The image forming device according to Item 1, wherein the feature is the amount of spatial information required from the time the user instructs execution of the print job to the time the print job is executed and a printed matter on which an image is formed is obtained.

[0084] According to this aspect, whether or not to execute reduction control to reduce the frictional force generated between the cleaning unit and the image carrier is determined based on the amount of spatial information required from when a user issues a print job instruction to when the print job is executed and a printed matter on which an image is formed is obtained. Therefore, reduction control can be executed when there is a high probability that the amount of spatial information will exceed the time required to execute reduction control.

[0085] (Item 3) The image forming apparatus according to Item 2, wherein the spatial information amount indicates the time required from when the user issues an instruction to execute the print job until when the printed matter is obtained.

[0086] In this aspect, the amount of spatial information is the time required from when a user issues a print job command to when the user receives the printed matter, which prevents the time required from when a user issues a print job command to when the user receives the printed matter from being too long, thereby preventing a decrease in user convenience.

[0087] (Item 4) The image forming apparatus according to item 2, wherein the amount of spatial information indicates a distance from a first position where the user instructs execution of the print job to a second position where the image forming apparatus is located.

[0088] The spatial information volume is the distance between a first location where a user instructs the execution of a print job and a second location where an image forming device is located. Therefore, the execution of a print job that has undergone reduction control can be completed between the time the user instructs the execution of a print job and the time the user obtains the printed material, preventing a decrease in user convenience.

[0089] (Item 5) The image forming apparatus according to item 4, further comprising a position information storage unit that stores the first position and the second position.

[0090] According to this aspect, it is easy to calculate the distance from the first position to the second position where the image forming device is disposed.

[0091] (Item 6) The image forming apparatus according to item 1, wherein the determination unit determines whether or not to execute the reduction control based further on history information of image forming operations.

[0092] According to this aspect, whether or not to execute the reduction control is determined further based on the history information of the image forming operation, and therefore, it can be determined to execute the reduction control when the frictional force generated between the cleaning unit and the image carrier is high.

[0093] (Item 7) An image forming apparatus that forms an image according to a print job, a cleaning unit that comes into contact with the image carrier and removes toner remaining on the image carrier; and a determination unit that determines whether or not to execute reduction control to reduce frictional force generated between the cleaning unit and the image carrier based on history information of the image forming operation.

[0094] According to this aspect, whether or not to execute the reduction control is determined further based on the history information of the image forming operation. Therefore, it is possible to determine not to execute the reduction control when the frictional force generated between the cleaning unit and the image carrier is not high, and to determine to execute the reduction control when the frictional force generated between the cleaning unit and the image carrier is high. Therefore, the cleaning ability of the cleaning unit can be maintained. As a result, it is possible to provide an image forming apparatus capable of suppressing the occurrence of tack-under.

[0095] (Item 8) The image forming apparatus according to item 6 or 7, wherein the history information is a ratio between the amount of toner supplied to the image carrier and the sliding distance over which the image carrier contacts and slides against the cleaning unit.

[0096] According to this aspect, whether or not to perform the reduction control is determined based on the ratio of the amount of toner supplied to the image carrier to the sliding distance over which the image carrier contacts and slides against the cleaning unit, and it is possible to detect an event in which the frictional force generated between the cleaning unit and the image carrier increases.

[0097] (Item 9) The toner image forming apparatus further includes a developing roller that supplies the toner to the image carrier, Item 8. The image forming apparatus according to item 6 or 7, wherein the history information is a ratio of a sliding distance calculated from the outer circumferential length and rotation speed of the developing roller to a sliding distance over which the image carrier contacts and slides against the cleaning unit.

[0098] According to this aspect, whether or not to execute the reduction control is determined based on the ratio of the sliding distance calculated from the outer circumferential length and rotation speed of the developing roller to the sliding distance over which the image carrier contacts and slides with the cleaning unit, and it is possible to detect an event in which the frictional force generated between the cleaning unit and the image carrier increases.

[0099] (Item 10) The image forming device according to any one of items 1 to 7, wherein the determination unit determines whether to execute the reduction control before the print job is executed in response to receiving an instruction to execute the print job.

[0100] According to this aspect, whether to execute reduction control is determined before the print job is executed after receiving an instruction to execute the print job. As a result, the frictional force generated between the cleaning unit and the image carrier is reduced before the print job is executed, so that the quality of the image formed by the print job is not degraded.

[0101] (Item 11) The image forming apparatus according to any one of Items 1 to 10, wherein the reduction control is control for reducing the relative speed between the cleaning unit and the image carrier.

[0102] According to this aspect, the relative speed between the cleaning unit and the image carrier is reduced, so that the frictional force between the cleaning unit and the image carrier can be reduced.

[0103] (Item 12) The cleaning device further includes an application unit that applies a lubricant to the cleaning unit, 12. The image forming apparatus according to any one of items 1 to 11, wherein the reduction control is a control for driving the application unit.

[0104] According to this aspect, since the lubricant is applied to the cleaning part, the frictional force between the cleaning part and the image carrier can be reduced.

[0105] (Item 13) The image forming apparatus according to any one of Items 1 to 12, wherein the reduction control is a control to make the image carrier carry a toner image and to make the cleaning unit remove the toner image.

[0106] According to this aspect, the lubricant contained in the toner is applied to the cleaning unit while the toner image carried by the image carrier is being removed by the cleaning unit, thereby reducing the frictional force between the cleaning unit and the image carrier.

[0107] (Item 14) An image forming method executed by an image forming apparatus that forms an image according to a print job, comprising: the image forming apparatus includes a cleaning unit that comes into contact with an image carrier and removes toner remaining on the image carrier; a user identification step for identifying a user who has instructed execution of the print job; and a decision step of deciding whether to perform reduction control to reduce the frictional force generated between the cleaning unit and the image carrier based on a characteristic amount unique to the user who instructed the execution of the print job.

[0108] According to this aspect, the cleaning ability of the cleaning unit can be maintained without reducing user convenience, and an image forming method capable of suppressing the occurrence of tack-under can be provided.

[0109] (Item 15) An image forming method executed by an image forming apparatus that forms an image according to a print job, comprising: the image forming apparatus includes a cleaning unit that comes into contact with an image carrier and removes toner remaining on the image carrier; and a determination step of determining whether to execute reduction control to reduce the frictional force generated between the cleaning unit and the image carrier based on history information of the image forming operation by the image forming apparatus.

[0110] According to this aspect, the cleaning ability of the cleaning unit can be maintained, and an image forming method capable of suppressing the occurrence of tack-under can be provided.

[0111] (Item 16) An image forming program that causes a computer to execute the image forming method according to item 14 or 15.

[0112] According to this aspect, the cleaning ability of the cleaning unit can be maintained without reducing user convenience, and an image forming program capable of suppressing the occurrence of tack-under can be provided.

[0113] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0114] 100 MFP, 130 document reading unit, 140 image forming unit, 150 paper feeding unit, 111 CPU, 112 communication I / F unit, 113 ROM, 114 RAM, 115 HDD, 116 facsimile unit, 118 external storage device, 118A CD-ROM, 20Y, M, C, K image forming units, 21 exposure device, 22 charging roller, 23 photosensitive drum, 24 developing unit, 25 primary transfer roller, 26 secondary transfer roller, 27 cleaning device, 28 belt cleaning blade, 30 intermediate transfer belt, 31 timing roller, 32 fixing roller, 41 cleaning blade, 43 holding unit, 45 collection brush, 47 collection roller, 49 collection screw, 51 user identification unit, 53 determination unit, 55 image forming control unit, 57 history information storage unit, 61 feature amount acquisition unit, 63 History information acquisition unit.

Claims

1. An image forming apparatus that forms an image in accordance with a print job, a cleaning unit that comes into contact with the image carrier and removes toner remaining on the image carrier; a user identification unit for identifying a user who has instructed execution of the print job; and a decision unit that decides whether to perform reduction control to reduce the frictional force generated between the cleaning unit and the image carrier based on a characteristic amount unique to the user who instructed the execution of the print job.

2. The image forming apparatus according to claim 1 , wherein the feature amount is a spatial information amount required from when the user instructs execution of the print job until the print job is executed and a printed matter on which an image is formed is obtained.

3. The image forming apparatus according to claim 2 , wherein the amount of spatial information indicates a time required from when the user issues an instruction to execute the print job until when the printed matter is obtained.

4. The image forming apparatus according to claim 2 , wherein the amount of spatial information indicates a distance from a first position where the user instructs execution of the print job to a second position where the image forming apparatus is located.

5. 5. The image forming apparatus according to claim 4, further comprising: a position information storage unit for storing the first position and the second position.

6. The image forming apparatus according to claim 1 , wherein the determination unit determines whether or not to execute the reduction control further based on history information of the image forming operation.

7. An image forming apparatus that forms an image in accordance with a print job, a cleaning unit that comes into contact with the image carrier and removes toner remaining on the image carrier; and a determination unit that determines whether or not to execute reduction control to reduce frictional force generated between the cleaning unit and the image carrier based on history information of the image forming operation.

8. 8. The image forming apparatus according to claim 6, wherein the history information is a ratio between the amount of toner supplied to the image carrier and a sliding distance over which the image carrier slides in contact with the cleaning unit.

9. a developing roller for supplying the toner to the image carrier; 8. The image forming apparatus according to claim 6, wherein the history information is a ratio between a sliding distance calculated from the outer circumferential length and rotation speed of the developing roller and a sliding distance over which the image carrier slides in contact with the cleaning unit.

10. The image forming apparatus according to any one of claims 1 to 7, wherein the determination unit determines whether to perform the reduction control before the print job is executed in response to receiving an instruction to execute the print job.

11. 8. The image forming apparatus according to claim 1, wherein the reduction control is a control for reducing the relative speed between the cleaning unit and the image carrier.

12. Further provided is an application unit that applies a lubricant to the cleaning unit, 8. The image forming apparatus according to claim 1, wherein the reduction control is a control for driving the application unit.

13. 8. The image forming apparatus according to claim 1, wherein the reduction control is a control for causing the image carrier to carry a toner image and for causing the cleaning unit to remove the toner image.

14. 1. An image forming method executed in an image forming apparatus that forms an image in accordance with a print job, comprising: the image forming apparatus includes a cleaning unit that comes into contact with an image carrier and removes toner remaining on the image carrier; a user identification step for identifying a user who has instructed execution of the print job; and a decision step of deciding whether to perform reduction control to reduce the frictional force generated between the cleaning unit and the image carrier based on a characteristic amount unique to the user who instructed the execution of the print job.

15. 1. An image forming method executed in an image forming apparatus that forms an image in accordance with a print job, comprising: the image forming apparatus includes a cleaning unit that comes into contact with an image carrier and removes toner remaining on the image carrier; and a determination step of determining whether to execute reduction control to reduce the frictional force generated between the cleaning unit and the image carrier based on history information of the image forming operation by the image forming apparatus.

16. An image forming program that causes a computer to execute the image forming method according to claim 14 or 15.

Images