JP2016194572A - Image forming apparatus, method of supplying developer, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that brings blades into contact with photoreceptors, the image forming apparatus capable of reducing frictional resistance between the photoreceptors and the blades.SOLUTION: A control part of a printer, when a count value of a first counter indicating the number of prints in double-sided printing reaches a first number CT1 or more (S19: YES), executes toner supply amount setting processing (S24) to increase the amount of a toner to be supplied. Thus, the number of prints in the double-sided printing is increased, which enables an increase in the amount of a toner to be supplied in accordance with an increase in heat of a cleaning blade.SELECTED DRAWING: Figure 4

Description

  The technology disclosed in this specification relates to an image forming apparatus that collects a developer image carried on a photoconductor using a blade, and in particular, adjusts the amount of developer supplied from the developing unit to the photoconductor during double-sided printing. The present invention also relates to a technique for reducing the frictional resistance between the photosensitive member and the blade.

  2. Description of the Related Art Conventionally, some electrophotographic image forming apparatuses include a cleaning device for collecting a toner image remaining on the surface of a photoreceptor (for example, Patent Document 1). The cleaning device disclosed in Patent Document 1 collects a toner image carried on the surface of a photoreceptor by scraping it off with a blade. The blade is made of an elastic material so as not to damage the surface of the photoreceptor. However, this type of blade may increase in hardness at low temperatures and may cause poor cleaning without successfully scraping off the toner image remaining on the photoreceptor. On the other hand, if the toner in the developing device stays in the device for a long time, the shape becomes irregular due to stirring, or external additives such as silica are embedded in the toner surface, and so-called toner deterioration occurs. Arise. Therefore, in the image forming apparatus disclosed in Patent Document 1, when the temperature inside the apparatus exceeds a predetermined temperature, the toner is forcibly consumed, and both cleaning failure and disposal of deteriorated toner are prevented. I am trying.

JP 2005-189552 A

  By the way, in this type of image forming apparatus, when the toner at the portion where the tip of the blade contacts the photoconductor is depleted, the frictional resistance between the blade and the photoconductor increases, and a squealing phenomenon occurs due to the blade. . Alternatively, there is a case where the frictional resistance increases and the leading end portion of the blade is pushed and bent in the rotation direction of the photosensitive member (hereinafter also referred to as “the blade is turned up”). Further, the blade softens as the temperature rises. Further, as the photosensitive member rotates, the end of the blade that contacts the photosensitive member is contracted by being pushed into the photosensitive member in the rotational direction of the photosensitive member, or when the blade is contracted to some extent, it is extended by the elastic force of the blade. In some cases, so-called stick-slip that vibrates by repeating expansion and contraction may occur. As a result, when the temperature in the apparatus rises, the above-described squeal phenomenon and blade turning are likely to occur.

  Further, the cause of the temperature rise of the blade can be attributed to the double-sided printing operation. Specifically, when the image is fixed on the sheet, heat is transferred from the fixing device to the sheet. In duplex printing, a sheet on which an image is fixed on one side by applying heat from a fixing device is reversed and conveyed again to a position where an image is formed by a photoconductor. For this reason, the heat of the sheet applied in the first fixing operation is transmitted to the photoconductor, and further to the blade in contact with the photoconductor. As a result, if double-sided printing is continued, the temperature of the blade rises, and a squealing phenomenon or the like may easily occur.

  The present application has been proposed in view of the above-described problems, and is an image forming apparatus in which a blade is brought into contact with a photoreceptor, and the image forming apparatus capable of reducing frictional resistance between the photoreceptor and the blade Another object is to provide a developer supply method and program.

  An image forming apparatus according to the present application is an image forming unit that forms a developer image, and is developed by a photosensitive member, a developing unit that supplies a developer to an electrostatic latent image formed on the photosensitive member, and a developing unit. An image forming unit comprising: a transfer unit that transfers the developer image to the sheet; a blade that is in sliding contact with the photoconductor and collects the developer image formed on the photoconductor; A first conveying unit that conveys the sheet to the forming unit; a fixing unit that fixes the developer image transferred to the sheet to the sheet; and a sheet that conveys the sheet on which the developer image has been fixed by the fixing unit to the paper discharge tray. 2 a conveyance unit, a reversal conveyance unit that reverses the sheet on which the developer image is fixed by the fixing unit, and conveys the sheet to the image forming unit, and a control unit. The developer is supplied to the latent image, and the developer image developed by the developing unit is a sheet. First surface printing process for transferring and fixing the transferred developer image on the sheet, reverse conveyance process for conveying the sheet subjected to the first surface printing process to the reverse conveyance unit, and electrostatic formed on the photosensitive member Second surface printing process for supplying developer to the latent image, transferring the developer image developed by the developing unit to the sheet subjected to the reverse conveyance process, and fixing the transferred developer image on the sheet, and the reverse conveyance The supply amount increases to increase the supply amount of the developer supplied from the developing unit to the photosensitive member per predetermined number of rotations of the photosensitive member in accordance with the increase in the rotational number of the photosensitive member when driving the unit and printing on both sides of the sheet And a supply process for supplying a developer corresponding to the supply amount increased in the supply amount increasing process to the photosensitive member.

  The image forming apparatus is configured to be able to perform double-sided printing by inverting a sheet on which a developer image is printed on a first surface by using a reverse conveyance unit and printing the developer image on a second surface of the sheet. ing. Further, the control unit rotates the photosensitive member and collects the developer image formed on the photosensitive member with a blade. The control unit increases the supply amount of the developer supplied from the developing unit to the photosensitive member per predetermined rotation number of the photosensitive member in accordance with the increase in the rotational number of the photosensitive member in double-sided printing. The agent is supplied to the photoreceptor. For example, the rotational speed of the photoconductor in double-sided printing increases in proportion to the increase in the number of printed sheets in double-sided printing. For this reason, in the image forming apparatus, the number of sheets to be printed on both sides increases, the amount of developer supplied increases as the blade heat rises, and the amount of developer recovered by the blade increases. Thus, it is possible to suppress the occurrence of a blade squealing phenomenon caused by stick-slip.

  According to the image forming apparatus and the like according to the present application, it is possible to reduce the frictional resistance between the photoconductor and the blade.

It is sectional drawing which shows schematic structure of the laser printer of 1st Embodiment. It is the schematic diagram which expanded the part in connection with the photosensitive drum of a laser printer. It is a block diagram which shows the electric constitution of a laser printer. 6 is a flowchart illustrating processing contents of a duplex printing process and a toner supply process. 6 is a flowchart illustrating processing contents of a duplex printing process and a toner supply process. 5 is a flowchart illustrating processing contents of toner supply amount setting processing. FIG. 4 is a diagram schematically illustrating a portion where a tip of a cleaning blade provided in a toner recovery unit contacts a surface of a photosensitive drum. It is a figure which shows a position correction table. It is a figure which shows a sheet size correction table. It is a figure which shows a basic weight correction table. It is a figure which shows a double-sided printing execution sheet number correction table. 12 is a flowchart illustrating processing contents of double-sided printing processing and toner supply processing in the second embodiment. 12 is a flowchart illustrating processing contents of double-sided printing processing and toner supply processing in the second embodiment. It is a figure which shows the position correction table in 2nd Embodiment. It is a figure which shows the sheet size correction table in 2nd Embodiment. It is a figure which shows the basic weight correction table in 2nd Embodiment. It is a figure which shows the double-sided printing execution sheet number correction table in 2nd Embodiment.

  Hereinafter, an embodiment in which an image forming apparatus according to the present invention is embodied in a laser printer 1 (hereinafter sometimes simply referred to as “printer”) will be described in detail with reference to the drawings. In the following description, explanation will be made using a direction based on the position of the user when using the printer 1 (an example of an image forming apparatus). That is, in FIG. 1, the left side toward the paper surface is “front side”, the right side toward the paper surface is “rear side”, the front side toward the paper surface is “left side”, and the rear side toward the paper surface is “right side”. To do. Further, the vertical direction toward the paper surface is defined as “vertical direction”.

  The printer 1 according to this embodiment is a direct transfer tandem color laser printer. As shown in FIG. 1, the printer 1 includes a substantially box-shaped main body housing 2. The main body housing 2 includes a paper discharge tray 3 and an upper cover 5. The paper discharge tray 3 is configured by a part of the upper surface of the main body housing 2 and stores sheets (paper, OHP sheets, etc.) P discharged from the inside of the main body housing 2 in a stacked state. The sheet P is a recording medium in the printer 1. A paper discharge port 4 is formed at the rear end portion of the paper discharge tray 3 and communicates with the inside of the main body housing 2. The upper cover 5 constitutes the upper surface of the main body housing 2 corresponding to the outer peripheral portion of the paper discharge tray 3. The printer 1 includes a paper feeding unit 10 (an example of a first conveyance unit), an image forming unit 20, a fixing unit 30, a paper conveyance unit 40 (an example of a second conveyance unit), and a re-conveyance unit 50. (An example of the reverse conveyance unit) is provided inside the main body housing 2.

  The paper feeding unit 10 is a mechanism unit that feeds the sheet P to the image forming unit 20, and is disposed below the main body housing 2. The paper feed unit 10 includes a paper feed tray 11 and a paper feed mechanism unit 12. The sheet feed tray 11 stacks sheets P before image formation in the printer 1. The paper feed tray 11 is mounted at the lower portion of the main body housing 2 so as to be able to be pulled forward.

  The paper feed mechanism unit 12 includes a paper feed roller, a separation roller, a separation pad, a registration roller, and the like, and is disposed at a position above the front end of the paper feed tray 11. The paper feed mechanism unit 12 pulls out the sheets P stored in the paper feed tray 11 and separates them one by one, and then conveys them to the belt unit 26 constituting the image forming unit 20.

  The image forming unit 20 is a mechanism unit that forms an image on one surface (front surface or back surface) of the sheet P, and is disposed above the sheet feeding unit 10 inside the main body housing 2. The image forming unit 20 includes a scanner unit 21, four image forming units 22, a belt unit 26, and a toner collecting unit 91.

  The scanner unit 21 is disposed in the upper part inside the main body housing 2 and includes a polygon motor, a polygon mirror, a laser light source, a reflection mirror, a lens, and the like. The scanner unit 21 emits a laser beam based on desired image data from a laser light source, and forms a photosensitive drum 23 (an example of a photosensitive member) constituting each image forming unit 22 via a polygon mirror, a reflecting mirror, a lens, and the like. An electrostatic latent image is generated on the surface of the substrate. The scanner unit 21 has four laser light sources (not shown) in the vicinity of the polygon mirror. Each laser light source emits laser light corresponding to one of black, yellow, magenta, and cyan.

  The four image forming units 22 are arranged below the scanner unit 21 and above the belt unit 26 from the front to the rear of the main body housing 2. Each image forming unit 22 corresponds to yellow, magenta, cyan, and black toner colors in order from the front. Each image forming unit 22 includes a photosensitive drum 23, a charger 24, a developing cartridge 25, and the like. In the following description, when it is necessary to distinguish and describe the four image forming units 22, as shown in FIG. 1, an alphabet corresponding to a color is attached after the image forming unit 22, and the image forming unit 22Y ( Yellow, image forming unit 22M (magenta), image forming unit 22C (cyan), and image forming unit 22K (black) will be described. Since each image forming unit 22 has the same configuration, the following description will mainly describe the configuration of the image forming unit 22K. The order of the toner colors shown in FIG. 1 is an example and can be changed as appropriate.

  The photosensitive drum 23 includes a grounded metal drum main body, and is configured by covering the surface layer with a positively chargeable photosensitive layer. The photosensitive layer is made of polycarbonate or the like. An electrostatic latent image based on image data is generated on the surface of the photosensitive drum 23, that is, the photosensitive layer, based on the laser light emitted from the scanner unit 21.

  The charger 24 is disposed at a predetermined distance from the surface of the photosensitive drum 23 on the diagonally upper rear side of the photosensitive drum 23. FIG. 2 is an enlarged schematic view of a portion related to the photosensitive drum 23. As shown in FIG. 2, the charger 24 is, for example, a scorotron charger, and can generate a corona discharge from the charging wire 71 to uniformly charge the surface of the photosensitive drum 23 to a positive polarity. .

  The developing cartridge 25 supplies toner to the electrostatic latent image generated on the surface of the photosensitive drum 23 and develops the electrostatic latent image to generate a toner image 98 (an example of a developer image, see FIG. 2). As shown in FIG. 1, it has a supply roller 83, a developing roller 85, and the like. Each of the developing cartridges 25 contains toner of any one color of yellow, magenta, cyan, and black. The toner is supplied to the surface of the photosensitive drum 23 as the supply roller 83 and the developing roller 85 rotate.

  The toner recovery unit 91 is a mechanism unit for recovering the toner image 98 (see FIG. 2) formed on the surface of the photosensitive drum 23. The toner recovery unit 91 is provided on the rear side of each photosensitive drum 23 and below the charger 24. As shown in FIG. 2, in the toner recovery unit 91, a cleaning blade 93 (an example of a blade) is accommodated in a recovery case 95. The cleaning blade 93 is formed in a substantially flat plate shape extending in the front-rear direction. The collection case 95 is formed in a substantially cylindrical shape that is long in the left-right direction, and an opening 97 is formed in a portion facing the photosensitive drum 23. The cleaning blade 93 is fixed to the collection case 95 so that the front end portion provided in the opening 97 is in sliding contact with the surface of the photosensitive drum 23 from the rear side. When the photosensitive drum 23 rotates, the toner image 98 remaining on the surface of the photosensitive drum 23 is scraped off by the cleaning blade 93 and falls into the recovery case 95 through the opening 97. Therefore, the toner image 98 scraped from the photosensitive drum 23 by the cleaning blade 93 is accommodated in the collection case 95.

  As shown in FIG. 1, the belt unit 26 is disposed below the four image forming units 22 and above the paper feeding unit 10, and conveys the sheet P toward the fixing unit 30. This is a mechanism for transferring the toner image 98 on the surface of the photosensitive drum 23 to the sheet P. The belt unit 26 includes a pair of belt support rollers 27, a conveyance belt 28, and four transfer rollers 29.

  The belt support roller 27 is disposed in the main body housing 2 so as to be separated from the front and rear. The belt support roller 27 is rotationally driven in a predetermined direction (clockwise direction in FIG. 1) when a driving force of a conveyance motor (not shown) is transmitted.

  The conveyor belt 28 is an endless belt made of a resin material such as polycarbonate, and is laid horizontally between a pair of belt support rollers 27. The conveyor belt 28 moves in a predetermined direction (clockwise direction in FIG. 1) as the belt support roller 27 rotates. Accordingly, when the sheet P is placed on the conveyance belt 28 by the sheet feeding unit 10 or the like, the sheet P is conveyed toward the rear of the main body housing 2 (in the direction of the fixing unit 30).

  The four transfer rollers 29 are provided inside the conveyance belt 28 and are arranged side by side at regular intervals along the front-rear direction of the main body housing 2. Each transfer roller 29 is disposed below each photoconductive drum 23 with the conveyance belt 28 interposed therebetween. Further, since each transfer roller 29 is in contact with the inner surface of the conveyance belt 28, it rotates as the conveyance belt 28 circulates. Here, when the sheet P is conveyed between the photosensitive drum 23 and the transfer roller 29 by the conveyance belt 28 during the printing process, a negative transfer bias is applied to the transfer roller 29 by constant current control. The At this time, the toner images 98 carried on the surface of each photosensitive drum 23 are sequentially transferred onto the sheet P by the transfer bias applied to the transfer roller 29. Further, when each photoconductor drum 23 is rotated without applying a transfer bias to the transfer roller 29, the toner image 98 carried on the photoconductor drum 23 is collected by the toner collecting unit 91.

  The fixing unit 30 is a mechanism unit that thermally fixes the toner image 98 transferred to the sheet P to the sheet P, and is disposed behind the belt unit 26 in the main body housing 2. The fixing unit 30 includes a heating roller 31 and a pressure roller 32. The heating roller 31 includes a heat source such as a halogen lamp and is disposed so as to be rotatable. The pressure roller 32 is disposed below the heating roller 31 and is in contact with the heating roller 31 so as to press it. The pressure roller 32 is driven to rotate as the heating roller 31 rotates. In other words, the fixing unit 30 is sandwiched between the heating roller 31 and the pressure roller 32 while heating the sheet P carrying the toner image 98. As a result, the fixing unit 30 thermally fixes the toner image 98 on the sheet P to the sheet P.

  A guide member 35 is disposed behind the fixing unit 30. The guide member 35 has a curved guide surface protruding rearward, and changes the conveyance direction of the sheet P on which the toner image 98 is thermally fixed to a predetermined direction (upward in FIG. 1).

  The paper transport unit 40 is a mechanism unit that transports the sheet P on which an image has been formed toward the paper discharge port 4 (in the direction E in FIG. 1). It performs the function of transporting to the transport unit 50. The paper transport unit 40 includes an intermediate transport roller 41 and a paper discharge unit 60 along a paper transport path 45 extending from above the fixing unit 30 to the paper discharge port 4.

  The intermediate conveyance roller 41 is constituted by a pair of rollers that can rotate forward and reverse, and sandwiches and conveys the sheet P conveyed on the paper conveyance path 45 above the fixing unit 30. When the sheet P is discharged to the discharge tray 3, the intermediate transfer roller 41 rotates in a predetermined direction to transfer the sheet P to the discharge unit 60 and the discharge port 4.

  The paper discharge unit 60 is a mechanism that discharges the sheet P to the paper discharge tray 3 through the paper discharge port 4, and is disposed in the vicinity of the paper discharge port 4 at the top of the main body housing 2. . Further, the paper discharge unit 60 performs a function of conveying the sheet P conveyed to a predetermined position to the re-conveying unit 50 (in the direction R in FIG. 1) when performing double-sided printing described later.

  The re-conveying unit 50 is provided in the lower part of the main body housing 2. The re-conveying unit 50 conveys the sheet P toward the image forming unit 20 via the sheet feeding unit 10 when the sheet P is switched back and conveyed by the paper discharge unit 60 or the like. That is, in this case, the sheet P passes through a path extending in the front-rear direction below the sheet feed tray 11 via the rear of the guide member 35 (path indicated by a broken line in FIG. 1), and the sheet feeding unit 10, It is conveyed to the image forming unit 20.

  The reconveying unit 50 includes a reconveying path 51 and a plurality of sets of reconveying rollers 52. The re-conveying path 51 extends in the vertical direction behind the guide member 35, and extends in the front-rear direction along the lower surface of the paper feed tray 11. The re-conveying path 51 conveys the sheet P conveyed downward from the paper discharge unit 60 and the intermediate conveying roller 41 to the front of the main body housing 2 and guides it to the paper feeding unit 10. Each re-conveying roller 52 is rotatably provided on the re-conveying path 51 at a predetermined interval. The re-conveying roller 52 conveys the sheet P forward of the main body housing 2 by being driven to rotate while being in contact with the sheet P.

  FIG. 3 is a diagram illustrating an electrical configuration of the printer 1. The control unit 101 of the printer 1 includes a CPU 103, a ROM 105, a RAM 107, an ASIC 108, a first counter 109, a second counter 110, and the like. The control unit 101 controls each unit of the printer 1 by executing various programs stored in the ROM 105 by the CPU 103. Alternatively, the control unit 101 controls each unit of the printer 1 by executing hardware processing by the ASIC 108. Here, the respective units are the image forming unit 20, the fixing unit 30, and the like described above. The ROM 105 stores a control program and various data. For example, the ROM 105 stores data such as a first number CT1, which will be described later, and a position correction table TB1 (see FIG. 8). The RAM 107 is used as a working memory when the CPU 103 executes various processes. The first counter 109 is used to measure the number of printed sheets P on which printing has been performed after toner supply is performed. When the first surface of the sheet P is printed, the first counter 109 counts as one sheet, and the second surface of the sheet P Even if is printed, the number of printed sheets increases by one. The second counter 110 is used to measure the cumulative number of printed sheets P on which duplex printing has been performed. The number of sheets P printed on the first side and the second side is one, and the number of printed sheets increases. To do. The first counter 109 and the second counter 110 may be realized by software by executing a predetermined program in the CPU 103 or may be realized by hardware.

  In addition, the printer 1 is provided with a temperature sensor 111 inside the rear side wall of the main body housing 2 (see FIG. 1). The temperature sensor 111 detects the temperature in the main body housing 2 and outputs the detected value to the control unit 101. The printer 1 also has a display unit 113 that displays various types of information. The display unit 113 has, for example, a configuration in which a capacitance type touch panel and a liquid crystal display type display panel are stacked in the thickness direction, and various input can be performed by pressing operation keys displayed on the touch panel. The configuration is such that operations can be performed. The control unit 101 changes the display content of the display panel or implements a copy function or a FAX function according to the content of an operation instruction on the touch panel of the display unit 113 from the user. The printer 1 also has an external interface 115 connected to the network. The printer 1 transmits / receives data such as a print job to / from an external PC connected to the network via the external interface 115.

  Next, the control content of the duplex printing process will be described. The control unit 101 executes double-sided printing by switching back the sheet P on which the image is formed on the first surface (front surface) by the paper transport unit 40, the re-transport unit 50, and the paper discharge unit 60 described above. To do. More specifically, the control unit 101 first feeds the sheet P from the paper feed tray 11 by the paper feed unit 10 and conveys the sheet P to the image forming unit 20. At this time, the first surface (front surface) of the sheet P faces the image forming unit 20. The control unit 101 conveys the sheet P backward on the belt unit 26 and transfers the toner image 98 formed on the photosensitive drum 23 of each image forming unit 22 onto the sheet P. The control unit 101 conveys the sheet P to which the toner image 98 has been transferred to the fixing unit 30, and causes the toner image 98 to be thermally fixed to the sheet P by the fixing unit 30. The control unit 101 causes the sheet conveyance unit 40 to convey the sheet P that has passed through the fixing unit 30 upward along the sheet conveyance path 45 and conveys the sheet P to the paper discharge unit 60. In the case of single-sided printing, that is, when an image is formed only on the first surface of the sheet P, the sheet P is transported to the paper discharge unit 60 by the paper discharge unit 60 through the paper discharge port 4. And discharged onto the paper discharge tray 3.

  Next, when forming an image on the second surface of the sheet P, the control unit 101 causes the sheet conveying unit 40 including the paper discharge unit 60 and the like to convey the sheet P to the re-conveying unit 50. Thereafter, the control unit 101 causes the reconveying unit 50 to convey the sheet P to the paper feeding unit 10 via the reconveying path 51. When the sheet P reaches the image forming unit 20, the first surface of the sheet P faces the conveyance belt 28, and the second surface located on the back side of the first surface faces each image forming unit 22. Thereafter, the control unit 101 forms an image on both the front and back sides of the sheet P by causing the image forming unit 20 and the fixing unit 30 to form an image on the second side, similarly to the first side. I do.

  In addition, the control unit 101 according to the present embodiment executes two types of printing methods, that is, a 21-side printing method (an example of a first printing method) and a 2413 printing method (an example of a second printing method) as double-sided printing methods. It is possible. For example, when executing a print job in which the 21 printing methods are set by the user, the control unit 101 prints the image of the second page on one side of the sheet P, and then reverses the sheet P to the other side. The process of printing the image of the first page on the surface is repeated for each sheet P. The print job is received from an external PC via the external interface 115, for example. Alternatively, the print job is input by the user operating the touch panel of the display unit 113 to execute a copy function or the like.

  In addition, when the control unit 101 executes a print job in which the 2413 printing method is set by the user, the control unit 101 continuously conveys the two sheets P by the belt unit 26 or the like, and causes the first sheet P to have two pages. After the image of the eye is printed, the image of the fourth page is printed on the second sheet P. Further, the control unit 101 inverts the two sheets P and sequentially prints the first page image on the back surface of the first sheet P and the third page image on the back surface of the second sheet P. Repeat the process.

  Next, the double-sided printing processing operation will be described with reference to FIGS. In the printer 1 of the present embodiment, when executing a print job in which double-sided printing is set, a process of supplying toner to the toner recovery unit 91 in order to prevent a squealing phenomenon of the cleaning blade 93 included in the toner recovery unit 91 Execute.

  First, at step (hereinafter, simply referred to as “S”) 11 shown in FIG. 4, the control unit 101 receives a print job for which duplex printing is set via the external interface 115, for example. Start the printing process according to the contents. The control unit 101 executes a program stored in the ROM 105 and starts processing according to the flowcharts shown in FIGS. The control unit 101 resets the second counter 110 (see FIG. 3) with the start of double-sided printing (S11). Note that the print job executed by the control unit 101 may be one print job or a plurality of continuous print jobs. The plurality of continuous print jobs referred to here are, for example, started double-sided printing and continuously driven without stopping the rotation of the conveyor belt 28 or the photosensitive drum 23 or without stopping for a predetermined time or more. In the meantime, it refers to a plurality of print jobs to be executed. In this case, the second counter 110 counts the total number of printed sheets that are printed in a continuous print job. The continuous print jobs may include not only double-sided print jobs but also single-sided print jobs.

  Next, the control unit 101 executes double-sided printing on the first sheet P based on the print job (S13). When completing the double-sided printing on the sheet P, the control unit 101 increments the first counter 109 by two and increments the second counter 110 by one (S17). Note that when the 2413 printing is executed in S13 and two sheets P are printed together, the control unit 101 increments the first counter 109 by four in S17 and the second counter 110. Count up two.

  Next, the control unit 101 reads the first number CT1 from the ROM 105 and the count value of the first counter 109 after starting the double-sided printing process, that is, the number of double-sided printed sheets is equal to or greater than the first number CT1. Whether or not (S19). The first number CT1 is set to a value corresponding to the interval of the number of printed sheets that requires toner supply in order to prevent the cleaning blade 93 from squeaking. That is, the control unit 101 executes toner supply (S29), which will be described later, every time the first sheet CT1 is printed. In response to determining that the count value of the first counter 109 is equal to or greater than the first sheet number CT1 (S19: YES), the control unit 101 executes the processes after S21 and supplies toner to the cleaning blade 93. Run.

  The control unit 101 sets the toner supply timing by counting the number of printed sheets. However, the method for setting the toner supply timing is not limited to this. For example, the control unit 101 may set the toner supply timing based on the number of rotations of the photosensitive drum 23 after starting double-sided printing. Alternatively, the control unit 101 may set the toner supply timing based on the elapsed time from the start of double-sided printing. Alternatively, the control unit 101 may set the toner supply timing based on the elapsed time from the start of the supply of power to the charger 24 with the execution of double-sided printing.

  In S19, when the control unit 101 determines that the count value of the first counter 109 is smaller than the first sheet number CT1 (S19: NO), there is another double-sided print job to be executed. Is determined (S23). In response to determining that there is no other print job to be executed (S23: YES), the control unit 101 ends the process. Further, in response to determining that there is another print job to be executed (S23: NO), the control unit 101 executes the processing from S13 again and continues double-sided printing.

  In S19, when the control unit 101 determines that the count value of the first counter 109 is equal to or greater than the first number CT1 (S19: YES), the count of the second counter 110 indicating the accumulated number of printed sheets. It is determined whether or not the value is greater than or equal to the second number CT2 (S21). The second number CT2 is the number of prints set according to the saturation temperature of the cleaning blade 93. More specifically, when double-sided printing is started and each device such as the fixing unit 30, the charger 24, and the photosensitive drum 23 is driven, the temperature in the main body housing 2 of the printer 1 rises. As the temperature in the main body housing 2 increases, the temperature of the cleaning blade 93 also increases. In the cleaning blade 93, stick slip occurs as the temperature rises, and a squealing phenomenon or turning-up easily occurs. That is, the squealing phenomenon of the cleaning blade 93 is likely to occur as the temperature in the main body housing 2 increases.

  On the other hand, if the temperature in the room where the printer 1 is installed is constant, the temperature inside the main body housing 2 is considered to reach a certain temperature and saturate if the printing operation is continued for a predetermined time (for example, 2 hours). Therefore, when the printing operation is continued for a predetermined time, the temperature of the cleaning blade 93 reaches a certain temperature and becomes saturated as the temperature in the main body housing 2 is saturated. Accordingly, it is considered that the temperature of the cleaning blade 93 increases until the predetermined number of printed sheets is reached, but it is difficult to increase when the predetermined number of sheets is exceeded. Therefore, in the printer 1 of the present embodiment, the number of prints at which the temperature in the main body housing 2 is saturated is set as the second number CT2. As will be described later, while the count value of the second counter 110 is less than or equal to the second number CT2 (S21: YES), the control unit 101 changes the amount of toner supplied to the cleaning blade 93 (S24). In response to determining that the count value of the two counter 110 is larger than the second number CT2 (S21: NO), the supply amount is fixed to a constant amount on the assumption that the temperature of the cleaning blade 93 is saturated to a constant temperature. (S27). Thereby, the control unit 101 can prevent excessive consumption of toner.

  In response to determining that the count value of the second counter 110 is smaller than the second number CT2 (S21: YES), the control unit 101 executes a toner supply amount setting process for setting the toner supply amount (S24). . FIG. 6 shows the processing content of the toner supply amount setting process. When the toner supply amount setting process is started, the control unit 101 reads a reference toner supply amount (hereinafter referred to as “reference toner amount”) TN from the ROM 105 in S41. The control unit 101 of the present embodiment fixes the toner supply amount supplied per unit area on the surface of the photosensitive drum 23 to a constant amount, and holds the toner image 98 in the sub-scanning direction width L (see FIG. 7). The toner supply amount supplied from the developing roller 85 to the toner collecting unit 91 via the photosensitive drum 23 is changed.

  FIG. 7 schematically illustrates a portion where the tip 93 </ b> A of the cleaning blade 93 provided in the toner recovery unit 91 contacts the surface of the photosensitive drum 23. The control unit 101 controls the laser light emitted from the scanner unit 21 and changes the width L in the sub-scanning line direction of the electrostatic latent image formed on the surface of the photosensitive drum 23. Thereby, the width L in the sub-scanning direction of the toner image 98 on the surface of the photosensitive drum 23 developed by the developing cartridge 25 is changed. As a result, the amount of toner supplied to the toner recovery unit 91 is changed.

  In the present embodiment, the reference toner amount TN is a set value that sets the width L in the sub-scanning direction to 5 mm, for example. When the toner is supplied, the control unit 101 sets the width in the sub-scanning direction to a constant width L and exposes the entire region along the main scanning direction to form an electrostatic latent image. For this reason, as shown in FIG. 7, the toner image 98 supplied to the toner recovery unit 91 is formed on the entire surface of the photosensitive drum 23 along the main scanning direction and the sub-scanning direction. When “5 mm” is set as the reference toner amount TN, the width L in the sub-scanning direction is set to 5 mm, and a toner image 98 is formed in a region along the main scanning direction. The shape of the toner image 98 shown in FIG. 7 is an example, and it is not necessary to form the entire surface of the photosensitive drum 23 along the sub-scanning direction and the main scanning direction, and other shapes, for example, the main scanning direction. A long oval shape may be used.

  Returning to the flowchart of FIG. 6, in the next S43, the control unit 101 reads the position correction table TB1 shown in FIG. 8 from the ROM 105, and sets the correction amount of the correction value A1. Here, as shown in FIG. 1, the four image forming units 22 correspond to the toner colors of yellow, magenta, cyan, and black in order from the upstream in the transport direction of the sheet P. Of the four image forming units 22, the image forming unit 22 </ b> K corresponding to black is the most downstream (the front side of the printer 1) and is closest to the fixing unit 30, and thus is affected by the heat generated in the fixing unit 30. easy. Therefore, it is considered that the temperature of the cleaning blade 93 of the toner recovery unit 91 corresponding to the image forming unit 22 </ b> K is likely to increase as compared with the cleaning blade 93 of the other toner recovery unit 91. Therefore, in the position correction table B1 shown in FIG. 8, the toner supply amount of the image forming unit 22K corresponding to black located most downstream is maximized. As the correction value A1, the largest value corresponding to black is set to “2 mm”. In this case, the control unit 101 adds the correction value A1 “2 mm” to “5 mm” of the reference toner amount TN as the width L (see FIG. 7) of the toner image 98 in the sub-scanning direction in S51 of FIG. “7 mm” is set, and the toner supply amount supplied from the image forming unit 22K to the toner collecting unit 91 is changed. The value of the correction value A1 in the position correction table TB1 shown in FIG. 8 is an example, and may be changed as appropriate according to the position of the image forming unit 22 and the like.

  In addition, since the image forming units 22Y, 22M, and 22C corresponding to the other three colors (such as yellow) other than black are separated from the fixing unit 30 by a certain distance, the influence of heat generated in the fixing unit 30 is small. it is conceivable that. On the other hand, at the time of double-sided printing, the sheet P that has been heat-applied by the fixing unit 30 and has finished printing on one side is again carried into the position of each image forming unit 22. In this case, among the plurality of image forming units 22, the photosensitive drum 23 of the image forming unit 22 </ b> Y corresponding to yellow located on the most upstream side first comes into contact with the sheet P to which heat has been applied. For this reason, the temperature of the photosensitive drum 23 of the image forming unit 22Y may increase. On the contrary, it is considered that the temperature of the photosensitive drum 23 decreases as the upstream side of the photosensitive drum 23 is deprived of the heat amount of the sheet P by the upstream photosensitive drum 23. Therefore, the correction value A1 of the position correction table TB1 is corrected in order from the upstream toward the downstream, the image forming unit 22Y “1 mm”, the image forming unit 22M “0.5 mm”, and the image forming unit 22C “0.2 mm”. Is set to be small. In S43, the control unit 101 sets the correction value A1 corresponding to the position of the image forming unit 22 as a correction value for each of the image forming units 22 based on the position correction table TB1.

  Next, in S45 of FIG. 6, the control unit 101 reads the sheet size correction table TB2 shown in FIG. 9 from the ROM 105, and sets the correction amount of the correction value A2. Here, it is considered that the larger the size of the sheet P, the larger the printing area, and the total amount of heat applied from the fixing unit 30 increases. For this reason, the amount of heat transferred from the sheet P to the photosensitive drum 23 when the sheet P after printing on one side again comes into contact with the photosensitive drum 23 increases as the size of the sheet P increases. Therefore, the correction value A2 of the sheet size correction table TB2 is set so that the correction amount increases as the size of the sheet P increases. The correction values A2 are A3 “0.9 mm”, A4 “0.5 mm”, and A5 “0.2 mm” in descending order of the size of the sheet P. Based on the size of the sheet P set in the print job, the control unit 101 searches for the corresponding correction value A2 in the sheet size correction table TB2, and sets the correction amount of the correction value A2. Note that the size of the sheet P and the value of the correction value A2 in the position correction table TB1 shown in FIG. 9 are examples, and other sizes and correction values may be set.

Next, in S47 of FIG. 6, the control unit 101 reads the basis weight correction table TB3 shown in FIG. 10 from the ROM 105, and sets the correction amount of the correction value A3. Here, “basis weight” refers to the weight per square meter (m ² ) of the sheet P. The sheet P tends to increase the heat capacity of the sheet P as the basis weight increases. Here, in the electrophotographic image forming apparatus such as the printer 1 of the present embodiment, the toner image 98 is appropriately applied to the sheet P in consideration of the heat amount for melting the toner and the heat amount absorbed by the sheet P. The amount of heat for fixing is applied. In consideration of the amount of heat absorbed by the sheet P, the amount of heat applied from the fixing unit 30 to the sheet P increases as the basis weight of the sheet P increases. As a result, as the sheet P has a larger basis weight, the sheet P stores more heat in one sheet. When the sheet P comes into contact with the photosensitive drum 23 in the second printing of double-sided printing, the sheet P It is considered that the amount of heat transferred from the toner to the photosensitive drum 23 and, consequently, the amount of heat transferred to the cleaning blade 93 increases. Therefore, the correction value A3 of the basis weight correction table TB3 is set so that the correction amount increases as the basis weight increases.

  As shown in FIG. 10, the correction value A3 corresponding to the sheet P having a small basis weight is “0 mm”. Further, the correction value A3 corresponding to the sheet P having a large basis weight is “0.3 mm”. Further, the correction value A3 corresponding to the sheet P having a larger basis weight is “0.7 mm”. The control unit 101 searches for the corresponding correction value A3 in the basis weight correction table TB3 based on the basis weight of the sheet P set in the print job, and sets the correction amount of the correction value A3.

  Next, in S49 of FIG. 6, the control unit 101 reads the double-sided printing number correction table TB4 shown in FIG. 11 from the ROM 105, and sets the correction amount of the correction value A4. The temperature of the cleaning blade 93 increases as the number of printed sheets P for duplex printing increases. Therefore, the control unit 101 increases the toner supply amount as the number of sheets P to be continuously printed, that is, the count value of the second counter 110 indicating the cumulative number of printed sheets increases. The correction value A4 of the double-sided printing number correction table TB4 is a correction value that increases the toner supply amount by a fixed amount “0.1 mm” every time the count value (continuous printing number) of the second counter 110 increases by five. Is set. Based on the count value of the second counter 110, the control unit 101 searches the double-sided printing number correction table TB4 and sets a correction value for the correction value A4.

  Note that, until the count value of the second counter 110 becomes larger than the second number CT2 (S21: YES in FIG. 4), the control unit 101 of the present embodiment counts the first counter 109 as described later. Each time the value becomes equal to or greater than the first number CT1 (S35 in FIG. 5: NO), a toner supply amount setting process is executed (S24). In other words, the toner supply amount setting process (S24) is not executed unless the first sheet CT1 is printed.

  Next, the control unit 101 calculates the toner supply amount by adding the correction amounts of the correction values A1 to A4 set in S43, S45, S47, and S49 to the reference toner amount TN (S51 in FIG. 6). In step S51, the control unit 101 calculates a toner supply amount for each image forming unit 22 (photosensitive drum 23) corresponding to each color. The control unit 101 stores the calculated toner supply amount for each photosensitive drum 23 in the RAM 107 (S53), and ends the toner supply amount setting process. For example, as an example, the toner supply amount calculated when the toner color is “yellow (most upstream)”, the sheet size is “A4”, the basis weight is “large”, and the count value of the second counter 110 is “5”. Are a reference toner amount TN “5 mm”, a correction value A1 (yellow: 1 mm), a correction value A2 (A4: 0.5 mm), a correction value A3 (more: 0.3 mm), and a correction value A4 (5 sheets: 0). 0.1 mm) is added to “6.9 mm”.

  Returning to FIG. 4, after executing the toner supply amount setting process in S <b> 24, the control unit 101 determines in S <b> 25 in FIG. 5 whether the next print job to be executed is a 2413-type print process. Here, in the 21-type printing process, after the toner image 98 is transferred to the front surface of the sheet P, the toner image 98 is transferred to the back surface of the sheet P to which heat has been applied by the fixing unit 30. The processing operation transfers the toner image 98 to the surface of the sheet P. For this reason, the photosensitive drum 23 comes into contact with the sheet P to which heat has been applied in one transfer operation twice. On the other hand, in the 2413 printing process, the photosensitive drum 23 is in continuous contact with the two sheets P that have passed through the fixing unit 30 and has been applied with heat. The temperature is likely to rise. Therefore, when executing a print job in which the 2413 method is selected as the printing method, the control unit 101 according to the present embodiment increases the toner supply amount as compared with the 21-type printing process.

  In response to determining that the next print job to be executed is the 2413 system (S25: YES), the control unit 101 further sets the toner supply amount (width L) set in S24 to, for example, “0.4 mm. ”Is increased (S28). The controller 101 supplies toner based on the increased toner supply amount (S29).

  On the other hand, in step S25, the control unit 101 determines that the print job to be executed next is not the 2413 system, that is, the 21 system (S25: NO), and does not change the toner supply amount set in S24. Then, the toner is supplied (S29).

  Further, when the control unit 101 determines in S21 that the count value of the second counter 110 is larger than the second number CT2 (S21: NO), the temperature of the cleaning blade 93 is a constant temperature as described above. The supply amount is fixed to a constant amount assuming that the toner is saturated (S27), and toner supply is executed (S29). In S27, the control unit 101 sets, for example, the toner supply amount (width L in the sub-scanning direction) to 9 mm.

  In S <b> 29, the control unit 101 controls the scanner unit 21 based on the set toner supply amount (width L in the sub-scanning direction), and the surface of the photosensitive drum 23 corresponding to each color is applied to each photosensitive drum 23. An electrostatic latent image corresponding to the set width L is formed. The control unit 101 rotates the photosensitive drum 23 to supply toner from the developing roller 85 to the photosensitive drum 23 to form a toner image 98. The control unit 101 rotates the photosensitive drum 23 without applying a transfer bias to the transfer roller 29, and collects the toner image 98 by the cleaning blade 93, so that a toner with a desired toner supply amount is supplied to the toner collection unit 91. It becomes possible to supply to. Further, the control unit 101 resets the count value of the first counter 109 because the toner supply is executed in S29.

  Next, based on the print job, the control unit 101 executes double-sided printing on one sheet P in the case of 21-style printing and two sheets P in the case of 2413-style printing (S31). When the double-sided printing on the sheet P is completed, the control unit 101 increments the first counter 109 by two each time the double-sided printing of one sheet P is completed in the case of 21-type printing. 110 is incremented by one. Further, in the case of the 2413 system, the control unit 101 increments the first counter 109 by four and increments the second counter 110 by two every time double-sided printing of two sheets P is completed (S33). .

  Next, the control unit 101 determines whether or not the count value of the first counter 109 is smaller than the first number CT1 (S35). In response to determining that the count value of the first counter 109 is greater than or equal to the first number CT1 (S35: NO), the control unit 101 executes the processing from S21 again.

  Further, in response to determining that the count value of the first counter 109 is less than the first number CT1 (S35: YES), the control unit 101 determines whether there is another double-sided print job to be executed. Is determined (S37). In response to determining that there is no other print job to be executed (S37: YES), the control unit 101 ends the process. Further, in response to determining that there is another print job to be executed (S37: NO), the control unit 101 executes the processing from S31 again and continues double-sided printing.

  Incidentally, the paper feed unit 10 is an example of a first transport unit. The image forming unit 22 is an example of a developing unit. The photoconductor drum 23 is an example of a photoconductor. The transfer roller 29 is an example of a transfer unit. The paper transport unit 40 is an example of a second transport unit. The re-conveying unit 50 is an example of a reverse conveying unit. The cleaning blade 93 is an example of a blade. The toner image 98 is an example of a developer image. The processes of S13 and S31 are an example of a first side printing process, a reverse conveyance process, and a second side printing process. The process of S24 is an example of a supply amount increasing process. The process of S29 is an example of a supply process. The process of S27 is an example of a first fixing process.

The above-described embodiment has the following effects.
The control unit 101 of the printer 1 executes a toner supply amount setting process every time the count value of the first counter 109 that counts the number of duplex printing sheets becomes equal to or greater than the first sheet number CT1 (S35: NO) (S24). Increase the toner supply amount. As a result, in the printer 1 of the present embodiment, the number of double-sided printed sheets increases, the amount of toner supplied increases as the temperature of the cleaning blade 93 rises, and the amount of toner collected by the cleaning blade 93 increases. By doing so, the frictional resistance between the photosensitive drum 23 and the cleaning blade 93 can be reduced. Further, by reducing the frictional resistance between the photosensitive drum 23 and the cleaning blade 93, it is possible to suppress the occurrence of a squeal phenomenon or the like of the cleaning blade 93 due to stick slip.

  As a control for changing the toner supply amount, the control unit 101 fixes the toner supply amount supplied per unit area on the surface of the photosensitive drum 23 to a constant amount, and holds the toner image 98 in the width L in the sub-scanning direction. The toner supply amount can be changed by changing.

  In S21, the control unit 101 supplies on the assumption that the temperature of the cleaning blade 93 is saturated to a constant temperature in response to the count value of the second counter 110 being greater than the second number CT2 (S21: NO). The amount is fixed to a fixed amount (9 mm) (S27), and toner supply is executed (S29). Thereby, it is possible to prevent the toner from being excessively consumed in supplying the toner to the cleaning blade 93.

  In S45 of FIG. 6, the control unit 101 sets the correction amount of the correction value A2 based on the sheet size correction table TB2 shown in FIG. The correction value A2 of the sheet size correction table TB2 is set so that the correction amount increases as the size of the sheet P increases. Accordingly, the control unit 101 corrects the toner supply amount according to the size of the sheet P based on the sheet size correction table TB2, thereby reducing the frictional resistance between the photosensitive drum 23 and the cleaning blade 93. be able to. Further, by reducing the frictional resistance between the photosensitive drum 23 and the cleaning blade 93, it is possible to more appropriately suppress the occurrence of the blade squealing phenomenon.

  In S47, the control unit 101 sets the correction amount of the correction value A3 based on the basis weight correction table TB3 shown in FIG. The correction value A3 of the basis weight correction table TB3 is set so that the correction amount increases as the basis weight of the sheet P increases. Accordingly, the control unit 101 can reduce the frictional resistance between the photosensitive drum 23 and the cleaning blade 93 by correcting the toner supply amount according to the basis weight based on the basis weight correction table TB3. it can. Further, by reducing the frictional resistance between the photosensitive drum 23 and the cleaning blade 93, it is possible to more appropriately suppress the occurrence of the blade squealing phenomenon.

  In S49, the control unit 101 sets the correction amount of the correction value A4 based on the double-sided printing execution sheet number correction table TB4 shown in FIG. The correction value A4 of the double-sided printing number correction table TB4 is a correction value that increases the toner supply amount by a fixed amount “0.1 mm” every time the count value (continuous printing number) of the second counter 110 increases by five. Is set. Accordingly, the control unit 101 corrects the toner supply amount according to the number of sheets P to be continuously printed on both sides based on the double-sided printing number correction table TB4, whereby the photosensitive drum 23 and the cleaning blade 93 are corrected. The frictional resistance between the two can be reduced. Further, by reducing the frictional resistance between the photosensitive drum 23 and the cleaning blade 93, it is possible to more appropriately suppress the occurrence of the blade squealing phenomenon.

  In S25 of FIG. 5, the control unit 101 sets the toner supply amount set in S24 when the next print job to be executed is the 2413 method (S25: YES) and when the print job is the 21 method (S25: NO). (Width L) is further increased (S28). Accordingly, the control unit 101 can reduce the frictional resistance between the photosensitive drum 23 and the cleaning blade 93 by increasing the toner supply amount in the 2413 type printing process as compared with the case of the 21 type. it can. Further, by reducing the frictional resistance between the photosensitive drum 23 and the cleaning blade 93, it is possible to more appropriately suppress the occurrence of the blade squealing phenomenon.

  The correction values A1 of the position correction table TB1 shown in FIG. 8 are the image forming unit 22Y “1 mm”, the image forming unit 22M “0.5 mm”, and the image forming unit 22C in this order from upstream to downstream in the conveyance direction of the sheet P. The correction amount is set to be “0.2 mm”. Based on the position correction table TB1, the control unit 101 corrects the toner supply amount according to the position of the photoconductive drum 23 of each image forming unit 22 arranged in the transport direction, and thereby the photoconductive drum 23, the cleaning blade 93, and the like. The frictional resistance between the two can be reduced. Further, by reducing the frictional resistance between the photosensitive drum 23 and the cleaning blade 93, it is possible to more appropriately suppress the occurrence of the blade squealing phenomenon.

  Next, a second embodiment in which the image forming apparatus according to the present invention is embodied will be described. In the following description, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted as appropriate. The flowcharts shown in FIGS. 12 and 13 show the processing contents of the duplex printing process and the toner supply process in the second embodiment. In the first embodiment, as a method for changing the toner supply amount, the toner supply amount is increased by increasing the width L in the sub-scanning direction. In the second embodiment, the toner supply amount is increased by decreasing the value of the first number CT1 that determines the timing of toner supply and increasing the frequency of toner supply.

  More specifically, as shown in FIG. 13, the control unit 101 waits until the double-sided printing process is completed (S37: NO) every time the count value of the first counter 109 becomes greater than or equal to the first number CT1 ( S35: NO), toner supply amount processing (S29) is executed. Therefore, by reducing the first number CT1, it is possible to increase the number of times the toner supply process (S29) is executed per predetermined rotation number of the photosensitive drum 23, and as a result, it is possible to increase the toner supply amount. It becomes.

  Note that the control unit 101 executes the toner supply process at a different frequency for each image forming unit 22, for example, executes the processes of the flowcharts shown in FIGS. 12 and 13 for each image forming unit 22 for each color in parallel. To process. In the parallel processing, the control unit 101 determines that the count value of the first counter 109 is equal to or greater than the first number CT1 in at least one of the four image forming units 22 (S35: NO). When the toner supply process (S29) is executed, control is performed so that the start of the printing process (S13, S31) in the other image forming units 22 is in a standby state until the toner supply process is completed. When the toner supply process (S29) in all the image forming units 22 is completed, the control unit 101 drives each image forming unit 22 to execute the printing process.

  First, the control unit 101 determines whether or not the count value of the second counter 110 is greater than or equal to the second number CT2 in S21 of FIG. In response to determining that the count value of the second counter 110 is less than the second number CT2 (S21: YES), the control unit 101 executes the toner supply frequency (hereinafter, referred to as “toner supply frequency”). A toner supply frequency setting process is set (S61). In this toner supply frequency setting process, similarly to the toner supply amount setting process (see FIG. 6) in the first embodiment, the toner supply frequency is changed using each table (see FIGS. 14 to 17). The toner supply frequency setting process is different from the first embodiment in the reference value (reference toner amount TN in the first embodiment) and the table used, but the processing procedure is the toner supply amount setting shown in FIG. Since this is the same as the processing, the description thereof and the flowchart are omitted.

  When the toner supply frequency setting process is started, the control unit 101 reads out the reference toner supply frequency from the ROM 105. The reference toner supply frequency is, for example, “50 sheets”. In this case, the control unit 101 sets 50 sheets as the default value of the first sheet number CT1, and executes toner supply (S29) every time 50 sheets are printed.

  For example, the control unit 101 reads the position correction table TB6 illustrated in FIG. 14 from the ROM 105, and sets the correction amount of the correction value A6. The correction value A6 of the position correction table TB6 is the same as the position correction table TB1 shown in FIG. 8 in order to maximize the toner supply amount of the image forming unit 22K corresponding to black located most downstream in the conveyance direction of the sheet P. The largest value “−10 sheets” is set as the frequency reduction range.

  Similarly to the position correction table TB1, the correction value A6 of the position correction table TB6 is set to “−5 sheets” so that the toner supply amount of each image forming unit 22 increases from upstream to downstream. The frequency reduction range of the image forming unit 22M “−2 sheets” and the image forming unit 22C “0 sheets” decreases in order. As described above, the control unit 101 executes the processes of the flowcharts shown in FIGS. 12 and 13 for each image forming unit 22 and performs parallel processing. Therefore, a value obtained by subtracting the reference toner supply frequency (for example, 50 sheets) by each of the four correction values A6 of the position correction table TB6 is set in advance as a reference toner supply frequency for each image forming unit 22. May be. In this case, the control unit 101 does not need to perform a correction process using the position correction table TB6 every time the toner supply frequency setting process (S61) is executed.

  Further, the control unit 101 corrects the toner supply frequency using each table (sheet size correction table TB7 and the like) shown in FIGS. 15 to 17 in the toner supply frequency setting process. Similarly to the sheet size correction table TB2 shown in FIG. 9, the sheet size correction table TB7 shown in FIG. 15 shortens the toner supply frequency as the size of the sheet P increases, and rotates the photosensitive drum 23 a predetermined time. The correction value A7 is set so that the toner supply amount per number increases. The correction values A7 are A3 “−2 sheets”, A4 “−1 sheets”, and A5 “0 sheets” in order from the largest sheet P size.

  Also, the basis weight correction table TB8 shown in FIG. 16 is similar to the basis weight correction table TB3 shown in FIG. The correction value A8 is set so that the toner supply amount per unit increases. The correction value A8 corresponding to the sheet P having a small basis weight is “0 sheets”. Further, the correction value A8 corresponding to the sheet P having a large basis weight is “−3 sheets”. Further, the correction value A8 corresponding to the sheet P having a larger basis weight is “−5 sheets”.

  Further, similarly to the double-sided printing number correction table TB4 shown in FIG. 11, the double-sided printing number correction table TB9 shown in FIG. The correction value A9 is set so that the toner supply amount per predetermined number of rotations increases. As the correction value A9, every time the count value of the second counter 110 (the number of continuously printed sheets) is increased by 5, a correction value is set to decrease the first sheet number CT1 by a certain amount “1 sheet” and shorten the toner supply frequency. Has been.

  Then, the control unit 101 subtracts the correction amount set based on each table (position correction table TB6, etc.) from the reference toner supply frequency (50 sheets), and the value of the subtraction result is the first number CT1. Set as. As a result, the execution frequency of the toner supply process (S29) is changed.

  Returning to FIG. 12, after executing the toner supply frequency setting process in S <b> 61, the control unit 101 determines in S <b> 25 in FIG. 13 whether the next print job to be executed is a 2413 printing process. As in the first embodiment, the control unit 101 further decreases the first number CT1 by “1” in response to determining that the next print job to be executed is the 2413 method (S25: YES). By doing so (S63), the toner supply frequency set in S61 is shortened.

  Next, the control unit 101 executes toner supply processing (S29). Unlike the first embodiment, the control unit 101 does not change the width L in the sub-scanning direction. Therefore, each time S29 is executed, the control unit 101 executes toner supply processing with a constant toner supply amount. That is, the control unit 101 increases the toner supply amount per predetermined number of rotations of the photosensitive drum 23 by changing the toner supply frequency while fixing the toner supply amount.

  Further, in response to the determination that the count value of the second counter 110 is greater than the second number CT2 in S21 of FIG. 12 (S21: NO), the control unit 101 performs cleaning as in the first embodiment. Assuming that the temperature of the blade 93 is saturated to a constant temperature, the supply frequency is fixed to a constant value (30 sheets) (S65, an example of a second fixing process). Thus, after fixing the toner supply frequency, the control unit 101 executes the toner supply process (S29) for every 30 sheets until all the printing processes are completed.

  Further, after executing S29 of FIG. 13, the control unit 101 executes double-sided printing based on the print job (S31), and counts up the first counter 109 and the second counter 110 (S33).

  Next, the control unit 101 determines whether or not the count value of the first counter 109 is smaller than the first number CT1 changed in S61, S63, and S65 (S35). In response to determining that the count value of the first counter 109 is greater than or equal to the first number CT1 (S35: NO), the control unit 101 executes the processing from S21 again. Even in such a configuration, the control unit 101 can obtain the same effects as those of the first embodiment described above by changing the value of the first number CT1, that is, the toner supply frequency.

  As described above, since the control unit 101 executes the toner supply process (S29) at a different frequency for each image forming unit 22, the toner in at least one of the four image forming units 22 is used. When the supply process (S29) is executed, the start of the printing process (S13, S31) in the other image forming units 22 is set in a standby state until the toner supply process is completed.

  In the second embodiment, the toner supply amount per predetermined rotation number of the photosensitive drum 23 is changed by changing the toner supply frequency. However, the width L in the sub-scanning direction of the first embodiment is changed. A method may be used in combination, and the toner supply amount may be changed by both the width L and the frequency.

Note that the present invention is not limited to the above-described embodiments, and various modifications and changes can be made without departing from the spirit of the present invention.
For example, in the first embodiment, the control unit 101 fixes the toner supply amount to be supplied per unit area on the surface of the photosensitive drum 23 as a toner supply amount changing process, but the present invention is not limited thereto. The total toner supply amount may be changed by changing the toner supply amount per unit area.
Further, in the first embodiment, the control unit 101 fixes the supply amount to a certain amount in response to the count value of the second counter 110 becoming larger than the second number CT2 (S21: NO) ( S27), not limited to this. For example, the control unit 101 may continue to increase the toner supply amount as the number of printed sheets increases without setting an upper limit.

In each of the above embodiments, the control unit 101 corrects the width L and the toner supply frequency using a plurality of tables (position correction table TB1, sheet size correction table TB2, etc.). However, at least one table is used. The correction process may be executed. For example, the toner supply amount of each image forming unit 22 may be the same amount regardless of the position of the image forming unit 22. Further, for example, the control unit 101 does not need to change the toner supply amount according to the size of the sheet P.
Further, in each of the above embodiments, the control unit 101 provides a difference in toner supply amount between the 21 method and the 2413 method, but the toner supply amount of both methods may be the same.
Further, the second printing method in the present application is not limited to the 2413 method, and may be a method in which, for example, three or more sheets are printed on both sides.

  In each of the above embodiments, the toner is supplied from the developing roller 85 to the exposed portion of the photosensitive drum 23 in the toner supply process (S29), but the present invention is not limited to this. For example, toner supply may be performed using so-called fog toner that moves from the developing roller 85 to an unexposed portion of the photosensitive drum 23. In this case, the control unit 101 controls the amount of fog toner supplied to the photosensitive drum 23 by controlling the potential difference between the charging bias applied to the photosensitive drum 23 and the developing bias applied to the developing roller 85, for example. May be. Then, the control unit 101 may change the toner supply amount by changing the potential difference according to the size of the sheet P, for example. Alternatively, the control unit 101 may change the supply frequency of supplying the fog toner according to the size of the sheet P, for example. Further, as the toner supply method, both the above-described exposed portion method and the unexposed portion method may be used in combination.

  Moreover, in each said embodiment, although the control part 101 was a structure provided with CPU103 and ASIC108, the structure of the control part 101 is not limited to this. For example, the control unit 101 may include a plurality of CPUs 103 or may include only the ASIC 108. The processing disclosed in each of the above embodiments may be executed by a single CPU 103, a plurality of CPUs 103, an ASIC 108, or a combination thereof. The processing disclosed in each of the above embodiments can be realized in various modes such as a recording medium or a method recording a program for executing the processing.

  In each of the above embodiments, the color printer 1 including a plurality of image forming units 22 is described as an example of the image forming apparatus of the present application. However, the present invention is not limited thereto, and a monochrome printer is applied as the image forming apparatus of the present application. Also good. Further, the image forming apparatus may be applied to a multi-function machine in which a copy function and a facsimile function are mounted alone or in an appropriate combination.

  Further, in each of the above embodiments, the direct transfer tandem printer 1 that directly transfers the toner image 98 to the sheet P is exemplified, but the present application is not limited to this, for example, via an intermediate transfer member or an intermediate conveyance belt. The present invention can also be applied to an intermediate transfer type printer that transfers the toner image 98 to the sheet P.

DESCRIPTION OF SYMBOLS 1 Laser printer (image forming apparatus), 3 Paper discharge tray, 10 Paper feed part (1st conveyance part), 11 Paper feed tray, 20 Image formation part, 22 Image formation unit (development part), 23 Photosensitive drum (photosensitive) Body), 29 transfer roller (transfer section), 40 paper transport section (second transport section), 50 re-transport section (reverse transport section), 93 cleaning blade (blade), 98 toner image (developer image), 101 control Part, P sheet.

Claims (12)

An image forming unit for forming a developer image,
A photoreceptor,
A developing unit for supplying a developer to the electrostatic latent image formed on the photoreceptor;
A transfer unit that transfers the developer image developed by the developing unit to a sheet;
A blade that slidably contacts the photosensitive member and collects a developer image formed on the photosensitive member; and
A first transport unit that transports the sheet from a paper feed tray to the image forming unit;
A fixing unit for fixing the developer image transferred to the sheet to the sheet;
A second transport unit that transports the sheet, on which the developer image has been fixed by the fixing unit, to a paper discharge tray;
A reversing conveyance unit that reverses the sheet on which the developer image is fixed by the fixing unit and conveys the sheet to the image forming unit;
A control unit,
The controller is
A developer is supplied to the electrostatic latent image formed on the photoconductor, the developer image developed by the developing unit is transferred to a sheet, and the transferred developer image is fixed to the sheet. One-side printing process;
A reverse conveying process for conveying the sheet subjected to the first surface printing process to the reverse conveying unit;
The developer is supplied to the electrostatic latent image formed on the photosensitive member, the developer image developed by the developing unit is transferred to the sheet subjected to the reverse conveyance process, and the transferred developer A second side printing process for fixing an image on the sheet;
The developer supplied to the photoconductor from the developing unit per a predetermined number of rotations of the photoconductor according to an increase in the number of rotations of the photoconductor when driving the reversal conveyance unit and printing on both sides of the sheet Supply amount increase processing for increasing the supply amount of
And a supply process for supplying a developer corresponding to the supply amount increased by the supply amount increase process to the photoconductor.   In the supply amount increasing process, the control unit fixes the amount of the developer supplied per unit area on the surface of the photoconductor to a constant amount and increases the width of the electrostatic latent image in the sub-scanning direction. The image forming apparatus according to claim 1, wherein the supply amount of the developer per a predetermined number of rotations of the photoconductor is increased.   The control unit executes a first fixing process for fixing the developer supply amount per predetermined rotation number of the photosensitive member to a constant amount in response to the rotation number of the photosensitive member becoming equal to or higher than the upper limit rotation number. The image forming apparatus according to claim 2.   The controller reduces the supply amount of the developer per a predetermined number of rotations of the photoconductor by shortening a time interval for supplying the developer from the developing unit to the photoconductor in the supply amount increasing process. The image forming apparatus according to claim 1, wherein the image forming apparatus is increased.   The said control part performs the 2nd fixing process which fixes the said time interval to a fixed space | interval according to the rotation speed of the said photoconductor becoming more than upper limit rotation speed. Image forming apparatus.   The control unit increases the supply amount of the developer per a predetermined number of rotations of the photoconductor in accordance with an increase in the size of the sheet to be printed in the supply amount increase process. The image forming apparatus according to claim 1.   The control unit increases the supply amount of the developer per a predetermined number of rotations of the photoconductor in accordance with an increase in basis weight of the sheet to be printed in the supply amount increase process. The image forming apparatus according to claim 1.   In the supply amount increasing process, the control unit increases the developer supply amount per predetermined rotation number of the photosensitive member by a certain amount each time the continuous rotation number of the photosensitive member increases by a certain rotation number. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: The controller is
A first type printing process in which printing on both sides of one sheet is performed continuously on each side;
A second-type printing process is performed in which printing on both sides of a plurality of sheets is performed by continuously printing on one side of the plurality of sheets and continuously printing on the other side of the plurality of sheets. And
As the supply amount increasing process, the supply amount of the developer per predetermined rotation number of the photoconductor according to the second type printing process is set to the predetermined amount of rotation of the photoconductor corresponding to the first type printing process. 9. The image forming apparatus according to claim 1, wherein the image forming apparatus increases the developer supply amount. A plurality of the photoreceptors are provided along a transport direction in which the first transport unit transports the sheet,
A plurality of the developing units are provided corresponding to each of the plurality of photoconductors,
The controller is
As the supply amount increasing process, the supply amount of the developer per a predetermined number of rotations of the photoconductor supplied to each of the plurality of photoconductors is sequentially increased from the downstream to the upstream in the transport direction. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. An image forming unit for forming a developer image, comprising: a photosensitive member; a developing unit that supplies a developer to an electrostatic latent image formed on the photosensitive member; and a developer image developed by the developing unit The image forming unit comprising: a transfer unit that transfers to the photoconductor; and a blade that is in sliding contact with the photoconductor to collect the developer image formed on the photoconductor; and the image forming unit that removes the sheet from the paper feed tray. A first conveying unit that conveys the sheet to the sheet, a fixing unit that fixes the developer image transferred to the sheet to the sheet, and the sheet on which the developer image is fixed by the fixing unit to a discharge tray. A developer supply method in an image forming apparatus, comprising: a second transport unit that transports; and a reverse transport unit that reverses the sheet on which the developer image has been fixed by the fixing unit and transports the sheet to the image forming unit. There,
A developer is supplied to the electrostatic latent image formed on the photoconductor, the developer image developed by the developing unit is transferred to a sheet, and the transferred developer image is fixed to the sheet. One-side printing step;
A reverse conveyance step for conveying the sheet subjected to the first surface printing process to the reverse conveyance unit;
The developer is supplied to the electrostatic latent image formed on the photosensitive member, the developer image developed by the developing unit is transferred to the sheet subjected to the reverse conveyance process, and the transferred developer A second side printing step for fixing the image to the sheet;
The developer supplied to the photoconductor from the developing unit per a predetermined number of rotations of the photoconductor according to an increase in the number of rotations of the photoconductor when driving the reversal conveyance unit and printing on both sides of the sheet A supply amount increasing step for increasing the supply amount of
And a supplying step of supplying a developer corresponding to the supply amount increased by the supply amount increasing process to the photoconductor. An image forming unit for forming a developer image, comprising: a photosensitive member; a developing unit that supplies a developer to an electrostatic latent image formed on the photosensitive member; and a developer image developed by the developing unit The image forming unit comprising: a transfer unit that transfers to the photoconductor; and a blade that is in sliding contact with the photoconductor to collect the developer image formed on the photoconductor; and the image forming unit that removes the sheet from the paper feed tray. A first conveying unit that conveys the sheet to the sheet, a fixing unit that fixes the developer image transferred to the sheet to the sheet, and the sheet on which the developer image is fixed by the fixing unit to a discharge tray. For an image forming apparatus comprising: a second transport unit that transports; and a reverse transport unit that reverses the sheet on which the developer image has been fixed by the fixing unit and transports the sheet to the image forming unit.
A developer is supplied to the electrostatic latent image formed on the photoconductor, the developer image developed by the developing unit is transferred to a sheet, and the transferred developer image is fixed to the sheet. One-side printing process;
A reverse conveying process for conveying the sheet subjected to the first surface printing process to the reverse conveying unit;
The developer is supplied to the electrostatic latent image formed on the photosensitive member, the developer image developed by the developing unit is transferred to the sheet subjected to the reverse conveyance process, and the transferred developer A second side printing process for fixing an image on the sheet;
The developer supplied to the photoconductor from the developing unit per a predetermined number of rotations of the photoconductor according to an increase in the number of rotations of the photoconductor when driving the reversal conveyance unit and printing on both sides of the sheet Supply amount increase processing for increasing the supply amount of
And a supply process for supplying a developer corresponding to the supply amount increased by the supply amount increase process to the photosensitive member.

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