JP2007304371A - Image forming apparatus and operating method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress increase in toner consumption due to the formation of a toner band while developing effects to suppress the occurrence of an abnormal noise when printing on a cardboard or an OHP sheet. <P>SOLUTION: The number of times of reduction cycles when printing on the cardboard or the like is measured, and when the number of times becomes equal to or exceeding a prescribed threshold, the toner image (toner band) that does not directly contribute to the printing is formed on the photoreceptor drum. Consequently, lubricity by the toner is applied between a blade for removing the toner remaining on the photoreceptor drum and the contact surface with the blade so as to prevent the occurrence of the abnormal noise even when the cardboard or the like is conveyed at low speed so as to print on the cardboard or the like. When the judgement condition is below the threshold even though the cardboard or the like is conveyed at low speed, the toner band is not formed, so that the toner consumption resulting from the formation of the toner band is suppressed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus, and more particularly to a technique for suppressing abnormal noise generated when printing thick paper or the like.

  Printing is performed by forming a toner image on a photosensitive drum on which a latent image is optically formed, performing primary transfer onto the transfer belt, and then performing secondary transfer from the transfer belt to a recording medium such as paper. An image forming apparatus is known. In such an image forming apparatus, when thick paper or OHP (over head projector) paper is used as a recording medium, the conveyance speed of the recording medium when transferring a toner image is normal printing paper (plain paper). Compared to late. This is because when an image is formed on an OHP sheet which is a resin film, it is necessary to sufficiently melt the toner so that the toner is smoothly distributed on the OHP sheet. This is because it is necessary to perform control to slow down the rotation speed of the roller and sufficiently apply heat to the toner and the OHP sheet. Also, when passing a recording medium having a large heat capacity such as thick paper, it is necessary to slow down the rotation speeds of the fixing roller and the pressure roller in order to sufficiently secure the fixing property.

  Incidentally, a blade for scraping off toner remaining after the transfer is in contact with the photosensitive drum and the transfer belt. The contact state between the blade and the photosensitive drum is adjusted so that no abnormal noise (particularly chatter noise) is generated by rubbing. However, when printing on the above-described thick paper or OHP paper, abnormal noise is likely to occur due to a decrease in the conveyance speed. This is due to the fact that the blade moves relatively slowly with respect to the photosensitive drum and the like, so that slippage between the two becomes worse and intermittent catching occurs.

  As a technique for dealing with this problem, there is a method of forming a toner band (band image) on a photosensitive drum. For example, in the process of transferring the toner images of each color of YMCK (Yellow, Magenta, Cyan, black) on the transfer belt, the first color toner image is first formed on the transfer belt, A second color toner image is formed, and thus a color toner image is formed. In this method, a blank area exists between the first color image and the second color image on the transfer belt. The toner band described above is a belt-like toner image formed in a region on the photosensitive drum corresponding to the blank region. The toner band is not transferred onto the recording medium and is eventually scraped off by the blade. At the time of scraping, the lubricity due to the lubricating component contained in the toner is reduced between the photosensitive drum and the blade. Given in between. This lubricity improves slipperiness between the photosensitive drum and the cleaning blade and suppresses the generation of abnormal noise. This technique is described in Patent Document 1, for example.

JP 2001-125458 A

  However, the toner used in the toner band does not contribute to image formation on the recording medium, and is consumed for lubrication. Therefore, the toner consumption increases. SUMMARY OF THE INVENTION An object of the present invention is to provide a technique for suppressing the generation of abnormal noise during printing on thick paper or OHP paper by forming a toner band, and at the same time, suppressing an increase in toner consumption due to the formation of the toner band.

  The image forming apparatus according to the present invention includes a photosensitive member on which an electrostatic latent image is formed, a developing unit that forms a toner image corresponding to the electrostatic latent image on the photosensitive member, and a transfer on which the toner image is transferred. Means, cleaning means for removing toner remaining on the surface of the photoconductor after the toner image is transferred, and whether the lubricity between the cleaning means and the surface of the photoconductor is at a predetermined level. Determining means for determining whether or not the determining means determines that the lubricity is not at a predetermined level, and forms a toner image that is not transferred to the surface of the photosensitive member by the developing means. It is characterized by that.

  According to the present invention, when the degree of lubricity between the surface of the photoreceptor and the cleaning means is determined, and it is determined that the lubricity is poor, in order to provide lubricity, finally, A toner image that is not used for image formation is formed on the surface of the photoreceptor. If it is determined that the lubricity is not poor, the toner image that is not used for the image formation is not formed, and the image forming process is executed. In this way, lubrication is effectively imparted between the photosensitive member and the cleaning means by forming a toner image that is not used for image formation, and the generation of abnormal noise is suppressed, and at the same time, wasteful consumption of toner is reduced. Can be suppressed. The toner image that is not finally used for image formation on the recording medium is referred to as a toner band. The toner band is usually formed in a band shape in order to effectively impart lubricity. However, the pattern of the toner image that functions as a toner band is not limited to a belt shape.

  A photoconductor on which an electrostatic latent image is formed is a member on which an electrostatic latent image is formed by an exposure operating device called ROS (raster optical scanner). An example of the photoreceptor is a photoreceptor drum. The developing unit is a unit that supplies toner onto the photoreceptor on which the electrostatic latent image is formed, and forms a toner image corresponding to the latent image on the surface of the photoreceptor. The transfer means is a mechanism for transferring the toner image on the photoconductor to the transfer partner. Examples of the transfer partner include a transfer belt for performing primary transfer and a transfer drum. In addition, a storage medium such as paper may be a direct transfer partner. The cleaning means is a means for removing toner remaining after transfer from the surface of the photoconductor. Blades, wires, and other toner that scrape off the toner remaining after transfer from the surface of the photoconductor are removed from the surface of the photoconductor. Mention may be made of suitable contact members that can be scraped off.

  In the present invention, the determination means determines whether one or more selected from the number of repetitions of the deceleration mode for reducing the conveyance speed of the recording medium and the image forming amount in the deceleration mode is equal to or greater than a predetermined value. Is desirable. According to this aspect, since it is difficult to directly determine the lubricity between the surface of the photoreceptor and the cleaning unit, the above parameters are indirectly used as an index for determination. Lubricity is evaluated. These determination conditions are not limited to single use, and a plurality of them can be combined.

  Examples of the deceleration mode include a case where the conveyance of a recording medium such as a thick paper or an OHP sheet needs to be delayed compared to a normal sheet. The recording medium for which the conveyance speed has to be slowed is not limited to thick paper or OHP paper, and can be a medium that takes time for secondary transfer and fixing as compared with plain paper. In addition, as the deceleration mode, a special image printing mode such as a high-definition printing mode that requires a low sheet conveyance speed can be selected. That is, a mode in which the rotational speed of the photosensitive drum and the transfer speed of the transfer belt must be made slower than those during normal printing can be regarded as a deceleration mode in the present invention.

  For example, it is assumed that the cumulative number of images formed in the deceleration mode is adopted as the number of repetitions of the deceleration mode, and a threshold value is set as the value. In this case, when the number of sheets to be counted reaches that number, it is determined that there is an increased possibility that the lubricity between the photosensitive drum and the cleaning unit has become poor. Then, as a process for preventing the occurrence of abnormal noise, a toner image forming process for imparting lubricity is executed. The image formation amount is PV (print volume) and is a parameter for grasping the amount of formed image. As the image forming amount, for example, the amount of toner used and the rotational speed of the photosensitive drum can be employed.

  The predetermined value (threshold value) described above may be changed according to the temperature and / or humidity values. The occurrence of abnormal noise is caused when the cleaning unit and the toner image forming surface move relative to each other while being in contact with each other, and the sliding state is caught. This catch is related to the friction state between both members, but the friction state between both members is greatly influenced by temperature and humidity. Therefore, the effects of temperature and humidity are examined in advance, and the predetermined values are changed in real time according to the measured values of temperature and humidity, so that a more appropriate noise prevention effect and toner consumption suppression effect can be achieved. And can be pursued.

  The present invention can also be grasped as an operation method of the image forming apparatus. That is, according to the operation method of the image forming apparatus of the present invention, the determination step for determining whether or not the lubricity between the photosensitive member and the cleaning device is at a predetermined level, and the lubricity is not at the predetermined level. And a toner band forming step of forming a toner image that is not transferred onto the surface of the photoconductor.

  According to the present invention, when a predetermined condition for determining the lubricity between the cleaning unit and the toner image forming surface is satisfied, a process for forming a toner image for improving the lubricity is performed. By doing so, it is possible to suppress the generation of abnormal noise during printing of thick paper or OHP paper, and at the same time, it is possible to suppress an increase in toner consumption.

(1) First embodiment
(Constitution)
FIG. 1 is a conceptual diagram showing an outline of an image forming apparatus using the invention. FIG. 1 shows a color printer 100 which is an example of an image forming apparatus. The color printer 100 includes a one-drum type developing machine 101. The developing machine 101 includes four phenomenon units 102 corresponding to YMCK basic colors. The phenomenon unit 102 includes a toner bottle 102a and a toner supply mechanism 102b. Each of the four toner bottles 102a stores one of YMCK toners corresponding to each phenomenon unit 102.

  A photosensitive drum 103 is disposed in contact with the developing machine 101. The photosensitive drum 103 is partially exposed to scanning light emitted from a ROS (raster optical scanner) 104, and a latent image is formed on the surface thereof. The ROS 104 is a writing exposure scanning device, and includes a laser irradiation device 104a and an optical system 104b for guiding laser light. The developing machine 101 and the photosensitive drum 103 rotate in opposite directions in synchronization with each other. At this time, scanning light is irradiated from the ROS 104 to the photosensitive drum 103, thereby forming a latent image on the photosensitive drum 103. The surface of the photosensitive drum 103 is charged in accordance with the latent image, and is attracted to the electric field, so that one of the YMCK toners is selectively supplied to the photosensitive drum 103 from one developing unit 102 of the developing device 101. The In this way, any toner of YMCK adheres to the surface of the photosensitive drum 103 according to the latent image formed by the ROS 104, and a toner image corresponding to the latent image is formed.

  A cleaning device 105 is provided in the vicinity of the photosensitive drum 103. The cleaning device 105 has a function of bringing the blade 105 a into contact with the surface of the photosensitive drum 103 and scraping off the remaining toner using the rotational force of the photosensitive drum 103. The toner scraped off is collected by a toner collecting unit (not shown).

  A transfer belt 106 is disposed in contact with the photosensitive drum 103. Further, a primary transfer roller 108 is disposed at a position facing the photosensitive drum 103 with the transfer belt 106 interposed therebetween. A bias voltage necessary for transferring the toner image can be applied between the photosensitive drum 103 and the primary transfer roller 108. The transfer belt 106 is conveyed by the driving roller 109 at a speed synchronized with the rotation of the photosensitive drum 103. At this time, the transfer belt 106 is sandwiched between the photosensitive drum 103 and the primary transfer roller 108, and at that time, a bias voltage is applied between the photosensitive drum 103 and the primary transfer roller 108. The toner image is transferred from the photosensitive drum 103 to the transfer belt 106 (primary transfer). At this time, in the case of color, the primary transfer for each color of YMCK is performed four times, and the four color images are superimposed, and a color toner image is formed on the transfer belt 106. For monochrome, transfer is performed for one color in YMCK.

  A cleaning roller 110 is disposed in the vicinity of the transfer belt 106. The cleaning roller 110 applies a DC voltage to the transfer belt 106 and positively charges the toner remaining on the transfer belt 106 after the secondary transfer. The positively charged toner is collected on the photosensitive drum 103 by the action of an electric field of a DC voltage applied between the photosensitive drum 103 and the primary transfer roller 108. The toner collected on the photosensitive drum 103 is removed by the cleaning device 105 and collected by a toner collecting unit (not shown).

  A toner sensor 111 is disposed in the vicinity of the transfer belt 106. The toner sensor 111 is an optical sensor and monitors the state of toner optically attached to the transfer belt 106. The amount of consumed toner can be known from the output of the toner sensor 111. A mark detection sensor 121 is disposed in the vicinity of the transfer belt 106. A mark for position detection (not shown) formed on the transfer belt 106 is detected by the mark detection sensor 121. This position detection mark (not shown) is used as a mark for determining a position for primary transfer on the transfer belt 106.

  A paper cassette 123 that stores printing paper 122 is stored at the bottom of the color printer 100. The printing paper 122 is transported along the paper transport path 125 by a paper transport system typically indicated by reference numeral 124. Secondary transfer rollers 126a and 126b are arranged in the middle of the paper transport path 125. A toner image that is primarily transferred onto the surface of the transfer belt 106 by sandwiching the transfer belt 106 and the printing paper (not shown) that has been transported through the paper transport path 125 between the secondary transfer rollers 126a and 126b. Is further transferred to the printing paper.

  The printing paper on which the toner image is transferred moves along the paper conveyance path 125 and is conveyed between the fixing rollers 127a and 127b. The fixing roller 127b has a built-in heater, and heats the toner material constituting the toner image on the printing paper during the conveyance. By this heating, the toner is fixed, and an image is formed on the printing paper (that is, printing is performed). The printing paper on which printing has been performed is discharged from the discharge mechanism 128 onto the discharge surface 129. Reference numeral 130 denotes a paper conveyance path when double-sided printing is performed.

  In FIG. 1, reference numeral 131 denotes a control unit that controls the operation of the color printer 100. FIG. 2 is a block diagram showing an outline of a control system including the control unit 131. The control unit 131 includes a central processing unit (CPU) 201, a read only memory (ROM) 202, and a random access memory (RAM) 203. The CPU 201 has a function of supervising the operation of the entire control system shown in FIG. 2 and executing an operation procedure described later. The ROM 202 stores an operation program for executing an operation procedure to be described later and data necessary for the operation. This data includes determination conditions used in an operation procedure described later.

  The RAM 203 functions as a working area for temporarily storing program data and various data during execution of an operation procedure described later, and a storage unit for storing various data obtained in the operation procedure described later. The RAM 203 includes a nonvolatile memory, and necessary data is retained even when the power is turned off. For example, the RAM 203 stores data relating to the number of deceleration cycles and the image formation amount. The drive control circuit 205 is a circuit that controls the motor that drives the developing device 102, the photosensitive drum 103, the transfer belt 106, the fixing rollers 127 a and 127 b, and the printing paper conveyance system 124.

  The sensor 204 detects the rotation state and rotation angle of the motor driven by the drive control circuit 205, the conveyance state of the printing paper, the number of image formations, and the image formation amount. The sensor 204 also includes a mark detection sensor 121 and a toner sensor 111. In this embodiment, the amount of toner used obtained from the output of the toner sensor 111 is used as the image formation amount.

  In the above, an example of a one-drum type image forming apparatus using a developing unit in which four colors of YMCK are integrated and one photosensitive drum is shown. However, the present invention can also be applied to a tandem type image forming apparatus including a pair of a developing machine and a photosensitive drum for each color of YMCK.

(Operation example 1)
FIG. 3 is a flowchart illustrating an example of an operation procedure of the color printer having the configuration illustrated in FIGS. 1 and 2. An operation program for executing the processing procedure shown in the flowchart of FIG. 3 is stored in the ROM 202 of FIG. The ROM 202 stores a threshold value used for the determination in step S302. This threshold value is obtained experimentally in advance.

  In this example, when processing for image formation is started (step S301), it is determined whether or not the cumulative number of deceleration cycles stored in the RAM 203 or the image formation amount is equal to or greater than a predetermined threshold value. (Step S302). Here, the number of printed sheets in the deceleration mode is used as the number of deceleration cycles, and the amount of toner used is used as the image formation amount.

  If the determination in step S302 is YES, it is determined that the lubricity between the blade 105a and the photosensitive drum 103 is poor, and a toner band is formed (step S303). On the other hand, if the determination in step S302 is NO, it is determined that the lubricity is maintained, and the process proceeds to step S305, where the primary transfer process onto the transfer belt is executed.

  In step S303, a solid toner image is formed in a belt-like area on the photosensitive drum corresponding to the inter-image portion that does not require transfer onto the transfer belt 106. At this time, the toner band formed on the photosensitive drum 103 is turned off by turning off the bias voltage applied between the photosensitive drum 103 and the primary transfer roller 108 at the timing when the toner band passes between the photosensitive drum 103 and the primary transfer roller 108. Is not transferred onto the transfer belt 106 but remains on the photosensitive drum 103 and is scraped off by the blade 105a. At the time of scraping off, the lubricity between the photosensitive drum 103 and the blade 105a is improved by the lubricating component contained in the toner. As the toner used for forming the toner band, a color with a low consumption ratio may be selected in advance and used, or a toner with a low toner consumption may be selected as appropriate and used.

  After step S303, the determination data used for the determination in step S302 is reset (step S304). In this example, the accumulated count number of deceleration cycles and the accumulated value of image formation amount stored in the RAM 203 are reset to zero.

  If the determination in step S302 is NO, or after the determination data is reset in step S304, the primary transfer process in step S305 is executed. In this primary transfer process, first, a toner image of a basic color of YMCK is formed on the photosensitive drum 103 and is transferred onto the transfer belt 106. The toner remaining in the toner image forming area of the photosensitive drum 103 after the transfer is scraped off by the blade 105a. Next, similar processing is performed for the second basic color, and the toner image is superimposed on the first basic color toner image on the transfer belt. This process is also performed for the third and fourth basic colors. Thus, the primary transfer process shown in step S305 is executed.

  After step S305, processing for determining whether the medium (printing paper) on which image formation is performed is a thick paper or an OHP paper is executed (step S306). If it is thick paper or OHP paper, the paper transport speed is set to a predetermined low speed mode (step S307), and the process proceeds to step S308. In step S308, the determination data used in step S302 is updated. That is, the number-of-deceleration cycle data stored in the RAM 203 is incremented by 1, and the toner usage measured by the sensor 204 is added to the integrated value of the toner usage stored in the RAM 203, and the value is stored. Is done. If the determination in step S306 is NO, the mode is set to the same transport speed mode as when the transport speed of the printing paper is not changed, that is, when printing is performed on normal normal paper (step S309).

  When step S308 or step S309 is executed, the secondary transfer rollers 126a and 126b perform the secondary transfer of the toner image from the transfer belt 106 to the printing paper 122 transported through the transport system 125 by the operation of the secondary transfer rollers 126a and 126b. The toner is fixed using the fixing rollers 127a and 127b (step S310). The toner remaining on the surface of the transfer belt 106 after the secondary transfer is positively charged by the action of the cleaning roller 110 and collected on the photosensitive drum 103. Then, the image forming process ends (step S311).

  According to the process shown in FIG. 3, if the number of deceleration cycles or the image formation amount has reached the threshold during the printing operation for the previous page, the determination in step S302 is YES during the next printing operation, and the toner band in step S303. Is formed. By forming the toner band, the lubricity between the blade 105a and the photosensitive drum 103 is recovered. In the subsequent printing process, the toner band is not formed until the determination data reaches the threshold again. In this way, it is possible to suppress an increase in toner consumption due to the formation of the toner band while ensuring lubricity between the blade 105a and the photosensitive drum 103.

(Operation example 2)
Hereinafter, an operation example 2 different from the operation example 1 will be described. FIG. 4 is a flowchart showing the procedure of this operation example. In this case, when image formation is started (step S401), first, primary transfer processing from the photosensitive drum 103 to the transfer belt 106 is performed (step S402). The contents of the primary transfer process are the same as the contents of step S305 in FIG. After the primary transfer in step (S402), it is determined whether the printing paper 122 is a thick paper or an OHP paper (step S403). If the printing paper 122 is a thick paper or an OHP paper, the process proceeds to step S404. Otherwise, the speed is not changed, and the normal paper feeding speed is set (step S409). In step S404, the accumulated data of the number of deceleration cycles and the image formation amount stored in the RAM 203 is updated. The processing content of step S404 is the same as the processing content of step S308 in FIG.

  After step S404, the process proceeds to step S405, where it is determined whether the number of deceleration cycles or the image formation amount stored in the RAM 203 exceeds a threshold value. If the number of deceleration cycles or the image formation amount exceeds the threshold value, a toner band is formed (step S406), otherwise the process proceeds to step S408. When the toner band in step S406 is formed, the accumulated data of the number of deceleration cycles and the image formation amount stored in the RAM 203 is reset to 0 (step S407), and the process proceeds to step S408. Note that the processing content in step S406 is the same as the processing content in step S303 in FIG. 3, and the processing content in step S407 is the same as the processing content in step S304 in FIG.

  In step S408, the low speed mode is set in which the conveyance speed of the printing paper 122 is slower than that of plain paper, and the process proceeds to step S410. Moreover, also when step S409 is performed, it progresses to step S410. In step S410, the secondary transfer rollers 126a and 126b act to perform secondary transfer of the toner image from the transfer belt 106 onto the printing paper 122 transported through the transport system 125, and further to the fixing roller 127a and The toner is fixed using 127b. Then, the image forming process ends (step S411).

  According to the operation example shown in FIG. 4, when the number of deceleration cycles or the image formation amount reaches the threshold during the printing operation, the determination in step S405 is YES, and the toner band is formed in step S406. By performing the toner band forming process, the lubricity between the blade 105a and the photosensitive drum 103 is recovered. In the subsequent printing process, the toner band is not formed until the determination data reaches the threshold again. For this reason, it is possible to suppress an increase in toner consumption due to the formation of the toner band while ensuring lubricity between the blade 105a and the photosensitive drum 103.

(Operation example 3)
Hereinafter, an operation example 3 different from the operation example 1 and the operation example 2 will be described. FIG. 5 is a flowchart showing the procedure of this operation example. When image formation is started (step S501), primary transfer of the toner image from the photosensitive drum 103 onto the transfer belt 106 is performed (step S502). Next, it is determined whether or not the sheet 122 to be used is a thick sheet or an OHP sheet (step S503). If the sheet 122 is a thick sheet or an OHP sheet, the deceleration mode is set (step S504). The normal speed mode is set without changing (step S506). When the deceleration mode is set in step S504, the determination data is updated (step S505). After step S506 or step S505, secondary transfer onto the printing paper and toner fixing processing are executed (step S507), and the process proceeds to step S508. Note that the processing content in step S502 is the same as the processing content in step 305 in FIG. 3, and the processing content in step S505 is the same as the processing content in step S308 in FIG.

  In step S508, it is determined whether the number of deceleration cycles or the image formation amount is equal to or greater than a threshold value. If the number of deceleration cycles or the image formation amount is equal to or greater than the threshold value, a toner band is formed (step S509). Otherwise, the process ends (step S510). When the toner band is formed in step S509, the accumulated data regarding the number of deceleration cycles and the image formation amount are reset to 0 (step S509), and the process is terminated (step S510).

  According to the operation example shown in FIG. 5, when the number of deceleration cycles or the image formation amount reaches the threshold value during the printing operation, the determination in step S <b> 508 is YES, and the toner band is formed at the timing after the completion of the secondary transfer. Done. By forming the toner band, the lubricity between the blade 105a and the photosensitive drum 103 is recovered. In the subsequent printing process, the toner band is not formed until the determination data reaches the threshold again. By doing so, it is possible to suppress an increase in toner consumption due to the formation of the toner band while ensuring lubricity between the blade 105a and the photosensitive drum 103.

(2) Second Embodiment The threshold value used in step S302 of FIG. 3, step S405 of FIG. 4 or step S508 of FIG. 5 is not fixed, and may be set to change according to temperature and / or humidity conditions. . Lubricity between the blade 105a and the photosensitive drum 103 is greatly affected by temperature and humidity. Therefore, it is desirable to select an appropriate value corresponding to the temperature and / or humidity as the above threshold value, which is an index for estimating the lubricity.

  Therefore, in the present embodiment, a temperature sensor and a humidity sensor are arranged as the sensor 204 in FIG. 2 to detect the temperature and humidity in the apparatus. Further, the relationship between the optimum number of deceleration cycles corresponding to temperature and humidity and the threshold value (upper limit value) of the image formation amount is experimentally obtained in advance, and the data table is stored in the ROM 202.

  In actual operation, in the previous stage of step S302, step S405, or step S508, the data table in the ROM 202 is read, and the optimum threshold value for the temperature and humidity values at that time is selected using this data table. . Then, the determination in step S302, step S405, or step S508 is executed using this threshold value. In this way, it is possible to take in environmental parameters and select an appropriate toner band formation timing at that time. That is, it is possible to adjust the balance between the suppression of chatter noise and the suppression of toner usage during the low-speed conveyance of the sheet according to the state of the environment.

  The present invention can be used in an image forming apparatus such as a color printer, a FAX, a color copying machine, or a complex machine of these.

It is a conceptual diagram which shows the structure of the color printer using invention. FIG. 2 is a block diagram illustrating an outline of a control system of the color printer illustrated in FIG. 1. 3 is a flowchart illustrating an example of an operation of the color printer illustrated in FIG. 1. 3 is a flowchart illustrating an example of an operation of the color printer illustrated in FIG. 1. 3 is a flowchart illustrating an example of an operation of the color printer illustrated in FIG. 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Color printer, 101 ... Developing machine, 103 ... Photoconductor drum, 105 ... Cleaning device, 105a ... Blade for removing toner, 106 ... Transfer belt, 108 ... Primary transfer roller, 110 ... Cleaning roller, 127a ... Secondary transfer roller, 127b, secondary transfer roller, 131, control unit.

Claims (4)

A photoreceptor having an electrostatic latent image formed on the surface;
Developing means for forming a toner image corresponding to an electrostatic latent image on the photoreceptor;
Transfer means for transferring the toner image;
Cleaning means for removing toner remaining on the surface of the photoconductor after the toner image is transferred;
Determination means for determining whether the lubricity between the cleaning means and the surface of the photoconductor is at a predetermined level,
An image forming apparatus comprising: a toner image that is not transferred onto the surface of the photosensitive member by the developing unit when the determining unit determines that the lubricity is not at a predetermined level.   The determination means determines whether or not one or more selected from the number of repetitions of a deceleration mode for decreasing the conveyance speed of the recording medium and the image formation amount in the deceleration mode is equal to or greater than a predetermined value. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 2, wherein the predetermined value is changed according to a value of temperature and / or humidity. A determination step for determining whether the lubricity between the photoconductor and the cleaning device is at a predetermined level;
And a toner band forming step of forming a toner image that is not transferred onto the surface of the photoconductor when it is determined that the lubricity is not at a predetermined level. .

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