JP3566372B2 - Image forming device - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an electrophotographic image forming apparatus such as a copying machine and a laser beam printer using a process cartridge.
[0002]
[Prior art]
FIG. 8 shows a laser beam printer as an example of an electrophotographic image forming apparatus. FIG. 1 is a diagram schematically illustrating a configuration around a photosensitive drum of the laser beam printer 100. The laser beam printer 100 has, as an image carrier, a drum-shaped photoconductor (hereinafter, referred to as “photosensitive drum”) 101 that is rotatably instructed in the direction of arrow R1. Around the photosensitive drum 101, a charging roller (charging member) 102 that uniformly charges the surface of the photosensitive drum 101 in order along the rotation direction, and irradiates the surface of the photosensitive drum 101 with light to form an electrostatic latent image. Exposure device 103, developing device 104 for attaching toner to the electrostatic latent image to form a toner image, transfer roller (transfer member) 105 for transferring the toner image on photosensitive drum 101 onto transfer material P, surface of photosensitive drum 101 A cleaning device 106 for removing the transfer residual toner is provided. Further, a control device 107 for controlling these operations is arranged.
[0003]
The control device 107 converts picture or document data from an external device (not shown) such as a personal computer or a workstation into image data, and controls on / off of the exposure device 103 based on the image data. It also controls each device of the printer body.
[0004]
In the above-described laser beam printer 100, when the number of prints (image formations) increases by repeating image formation, the toner, which is a consumable, disappears, or the photosensitive drum 101 as a consumable member deteriorates. In these cases, toner is supplied to the developing device 104, or the photosensitive drum 101 is replaced. The cleaning device 106 is replaced when the photosensitive drum 101 is filled with waste toner removed from the surface. The replacement of the photosensitive drum 101 and the cleaning device 106 described above is usually performed by a service person. Therefore, there is a problem that the serviceability is lacking when urgently needed.
[0005]
In order to solve this problem, as shown in FIG. 9, a process cartridge 110 in which replacement units are integrated into one unit is used.
[0006]
This is configured by integrally incorporating a photosensitive drum 101, a charging roller 102, a developing device 104, and a cleaning device 106 into a cartridge container 111. The developing device 104 includes a developing container 104a for storing the toner T, a developing roller 104b for attaching the toner T to the electrostatic latent image on the photosensitive drum 101a, and a cleaning device 106 for transferring the toner T from the surface of the photosensitive drum 101. It has a cleaning blade 106a for scraping off residual toner and a developing container 106b for collecting scraped toner as waste toner. The components constituting the process cartridge 110 operate in substantially the same manner as the components of the laser beam printer shown in FIG. Therefore, when the process cartridge 110 is mounted on the image forming apparatus main body, the image forming apparatus can be configured like a laser printer shown in FIG. The process cartridge 110 can be easily attached to and detached from the print main body by a user, which is a so-called maintenance-free configuration. Therefore, the user consumes toner due to an increase in the number of prints, and outputs a blank white image. The process cartridge 110 can be used effectively up to the limit, that is, the usable limit.
[0007]
Here, a general image forming system using the above-mentioned contact type charging roller (charging member) will be described.
[0008]
In contact charging, a charging member to which a voltage is applied is brought into contact with a photosensitive drum (image carrier), and charges are directly transferred to the photosensitive drum to charge the surface of the photosensitive drum to a required potential. As compared with a corona discharge device that has been widely used in the past, the application voltage required to obtain a desired potential on the photosensitive drum surface can be reduced, and the amount of ozone generated in the charging process is extremely small. However, there are advantages such as eliminating the need for an ozone removal filter, simplifying the configuration of the exhaust system of the apparatus, and being maintenance-free.
[0009]
The above-described contact charging is performed, for example, in an image forming apparatus of an electrophotographic system (copier, laser beam printer) or an electrostatic recording system, a means for charging an image carrier such as a photoconductor, a dielectric, and other photosensitive drums. It has attracted attention as a substitute for corona discharge devices and has been put to practical use.
[0010]
In this contact charging method, in order to uniformly charge the surface of the photosensitive drum, an oscillating voltage (hereinafter, appropriately referred to as “DC bias”) superposed on an AC voltage (hereinafter, appropriately referred to as “AC bias”) is superimposed. (Referred to as "Japanese Patent Application Laid-Open No. 63-149669") in which a "biasing bias" is applied to a contact charging member, and the contact charging member is brought into contact with a photosensitive drum to perform charging.
[0011]
FIG. 10 shows one embodiment. The photosensitive drum 101 is, for example, a drum-shaped electrophotographic photosensitive member that is driven to rotate at a predetermined peripheral speed (process speed) in the direction of arrow R1. A charging roller 102 as a contact charging member is in contact with the photosensitive drum 101. The charging roller 102 includes a cored bar 102a and a conductive roller 102b such as a conductive rubber surrounding the outer periphery of the cored bar 102a. The charging roller 102 is pressed against the photosensitive drum 101 with a predetermined pressing force by the pressing force of the pressing springs 102c disposed at both ends of the cored bar 102a, and the rotation of the photosensitive drum 101 in the direction of arrow R1. Then, it is driven and rotated in the direction of arrow R2.
[0012]
A voltage applying power source 102d is connected to the charging roller 102 via a contact leaf spring (not shown) in contact with the cored bar 102a. The photosensitive drum 101 through the charging roller 102 by the power source 102, the vibrating voltage _{V AC} and the DC voltage _{V DC} and the voltage obtained by superimposing more than twice the peak-to-peak voltage _{V PP} of the charge starting voltage of the photosensitive drum 101 (V _AC + V _DC ) is applied, whereby the surface of the rotating photosensitive drum 101 is uniformly charged.
[0013]
FIG. 11 shows an image forming apparatus using the above-described contact charging method. The image forming apparatus shown in FIG. 1 receives a print signal from an external device such as a personal computer or a workstation, drives the photosensitive drum 101, and is charged to a predetermined potential by the charging roller 102. Hereinafter, formation of a latent image by the exposure device 3, development of an electrostatic latent image by the developing device 104, transfer of a toner image to the transfer material P by the transfer roller 105, fixing of the toner image on the transfer material P by the fixing device 112, and the like. After each step, a toner image is formed on the transfer material P.
[0014]
Here, the charging roller 102 and the cleaning blade 106a are in contact with the surface of the photosensitive drum 101, and the cleaning blade 106a is not transferred to the transfer material P and is not transferred to the transfer material P at the contact position with the photosensitive drum 101. The remaining toner is scraped off and collected in the cleaning container 106b as waste toner. When the cleaning blade 106a scrapes off the residual toner, the cleaning blade 106a gradually scrapes the surface of the photosensitive drum 101 via the residual toner at the contact position described above. The surface of the photosensitive drum 101 deteriorates as the number of prints increases. Therefore, when the surface is not cut at all, printing is performed using the deteriorated surface, and defects such as image deletion and filming occur. However, the surface of the photosensitive drum 101 is gradually removed as described above. As a result, the deteriorated portion is sequentially removed from the surface of the photosensitive drum 101, and a new portion is exposed. Then, printing is performed using this new portion, so that even if the number of prints increases, a print with good image quality can be obtained.
[0015]
[Problems to be solved by the invention]
However, the image forming apparatus (laser beam printer) having the above configuration has the following problems.
{Circle around (1)} Generation of fog image before occurrence of white spots In the above-described image forming apparatus, if image printing with a small printing rate is continued, the photosensitive drum 101 is excessively scraped before the guaranteed number of prints of the process cartridge 110, and the image is charged. This is caused by a decrease in the charging potential of the photosensitive drum 1 by the roller 102. More specifically, the guaranteed number of prints of the process cartridge 110 is guaranteed at a certain dot ratio (for example, 6000 sheets of A4, 4% printing). For this reason, when designing the process cartridge 110, the film thickness of the photosensitive layer of the photosensitive drum 101 is set to a film thickness that does not generate a fog image due to the photosensitive drum scraping even at the time of intermittent printing at the guaranteed number of prints in consideration of the dot ratio. ing. Therefore, when printing an image with a small printing rate is continued, printing can be performed more than the guaranteed number of prints, and when intermittent printing is continued, the photosensitive drum is excessively scraped. As a result, fogging occurs before the occurrence of a white missing image. In order to prevent this, the thickness of the photosensitive layer of the photosensitive drum 101 may be sufficiently increased. However, due to a decrease in efficiency in the production line of the photosensitive drum 101 due to the increase in the film thickness and an increase in material costs, the process There is a problem that the cost of the cartridge 110 increases.
{Circle around (2)} Increase in the amount of photosensitive drum scraping due to the use of the charging roller 102 This is because the image forming apparatus using the contact charging method (charging roller) is more sensitive than the conventional image forming apparatus using the corona charging method. The shaving amount may increase. The cause will be described as follows. The charging roller 102 as shown in FIG. 10, the voltage _(V AC _{+ V DC)} is applied by superimposing a DC voltage _{V DC} and oscillating voltage _{V AC} by the power supply 102d. Here, when the oscillating voltage V _AC is an AC component photosensitive drum 101 is charged, the discharge current flows to the photosensitive drum 101 according to the change of the oscillating voltage V _AC, the periodic variation of the discharge current, the photosensitive drum 101 can be stably charged.
[0016]
However, not all of the electric energy of the discharge current is used for charging the photosensitive drum 101, and part of the electric energy of the discharge current electrically stimulates the polymer material on the surface of the photosensitive drum, thereby causing the polymer material to be charged. Defects are likely to occur in molecular bonding. Thus, the surface of the photosensitive drum is easily scraped by sliding with the cleaning blade 106a via the toner. The photosensitive drum abrasion amount in the case of using the charging roller 102 as compared with the case of charging only by V _DC, it has been found that it is often the case for charging by superimposing V _AC to V _DC. This is a high value peak-to-peak voltage V _PP of V _AC have about twice or more the peak value of V _DC, also by periodically current value changes, the discharge current of the photosensitive drum surface cycle This is because a vibrational stimulus is likely to cause a defect in molecular bonding on the surface of the photosensitive drum.
[0017]
Accordingly, it is an object of the present invention to accurately detect the life of the photoconductor and prevent the occurrence of a fog image before the occurrence of white spots.
[0018]
[Means for Solving the Problems]
The invention according to claim 1, wherein a photosensitive member having a surface on which a toner image is formed, a contact charging member for charging the photosensitive member, and a non-volatile storage means for storing data corresponding to the total number of rotations of the photosensitive member In the image forming apparatus in which the process cartridge having the following configuration is detachably attached to the image forming apparatus main body and used, the data is updated in the nonvolatile storage means in accordance with the total number of rotations of the photoconductor. Controlling means, during a printing operation, a period during which the photoconductor rotates, a first period in which an AC voltage and a DC voltage are applied to the contact charging member, and a period during which the contact member is applied. A second period in which a DC voltage is applied and an AC voltage is not applied, wherein the control unit controls the data according to the total number of rotations of the photoconductor in the first period and the second period in the second period. According to the total number of rotations of the photoconductor Data corresponding to the total number of rotations of the photoconductor is obtained based on the data corrected to be smaller than the actual total number of rotations of the photoconductor, and the data is determined according to the total number of rotations of the nonvolatile storage unit. It is characterized in that data is updated .
[0021]
[Action]
Based on the above-described configuration, data on the total number of rotations of the photoconductor is stored in the nonvolatile RAM in the process cartridge by the control device via the read / write device. This data is updated each time the photoconductor rotates, and is, for example, a parameter that accurately indicates the wear state of the photoconductor. Therefore, when the image forming conditions, for example, the voltage applied to the charging member are set based on the latest data stored in the nonvolatile RAM, the surface of the photoconductor can be charged well.
[0022]
Further, for example, when the cleaning blade of the cleaning device is arranged in contact with the surface of the photoreceptor and the non-printing process in which the voltage applied to the charging member is only the DC voltage, the AC voltage and the DC voltage are used. The abrasion of the photoconductor surface by the cleaning blade is less than in the printing process in which the voltage is superimposed. Therefore, a correction is made to the rotation speed of the photoconductor during the non-process. Since the wear of the photoconductor is small because the AC voltage is not applied, the correction is made smaller by that amount. By doing so, the total number of rotations of the photoconductor can be grasped as a state closer to actual wear of the photoconductor.
[0023]
As described above, the photoconductor is rotated not only during the printing process but also during the non-printing process. The non-printing process includes the transfer of the transfer material in addition to the transfer of the transfer material in the printing process, and the photosensitive member is rotated during the latter transfer. Therefore, even when an image is formed on the same one transfer material, the longer the transfer material transport length of the transfer material transport path, the higher the number of rotations of the photoconductor. Therefore, the total number of rotations of the photoconductor is corrected according to the transfer material conveyance path used for image formation. Also in this case, similarly to the case where the correction is performed by the applied voltage, the total number of rotations of the photoconductor can be grasped as a state closer to actual wear of the photoconductor.
[0024]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<Example 1>
FIG. 1 shows an overall schematic configuration diagram of a laser beam printer as an example of an image forming apparatus according to the present invention.
[0025]
The laser printer M has a paper feed cassette 2 which accommodates a transfer material P to be printed (image formed) and is detachably mounted on a printer main body (image forming apparatus main body) 1. A paper presence / absence sensor 3 for detecting the presence / absence of the transfer material P in the paper feed cassette 2 and a paper feed sensor for feeding the transfer material P in the paper feed cassette 2 are provided above the leading end side of the paper feed cassette 2 in the mounted state. A paper feed roller 5 and a size sensor 4 (composed of a plurality of micro switches) for detecting the size of the transfer material P via the paper feed cassette 2 are provided in the front (left side in the figure). Have been.
[0026]
A registration roller pair 6 that synchronously conveys the recording material P is disposed downstream of the paper feed roller 5 in the conveyance direction of the transfer material P (a direction from the left to the right in the drawing). . A process cartridge 8 and a transfer charger 21 for forming a toner image on the recording material P based on a laser beam from a laser scanner unit 7 described below are disposed downstream of the registration roller pair 6.
[0027]
Further, a fixing device 9 for thermally fixing the toner image formed on the recording material P is provided downstream of the process cartridge 8, and a paper conveyance state of a paper discharge unit is detected downstream of the fixing device 9. A paper discharge sensor 10, a paper discharge roller 11 for discharging the recording material P, and a loading tray 12 for loading the printed recording material P are provided.
[0028]
The laser scanner unit 7 disposed on the upper part of the printer body 1 includes a laser unit 13 that emits a laser beam modulated based on an image signal (VDO signal) sent from an external device 28 described later, and a laser beam from the laser unit 13. A polygon mirror 14, an imaging lens group 15, and a return mirror 16 for scanning light onto a photosensitive drum 17, which will be described later, are configured as main components.
[0029]
A process cartridge 8 detachably mounted substantially at the center of the printer main body 1 is provided with a photosensitive drum (photosensitive member) 17, a charging roller (charging member) 19, a developing device 20, and a cleaning device 22 with respect to a cartridge container 18. It is integrated into a cartridge. The developing device 20 is configured to be capable of replenishing the toner, and the cleaning device 22 includes a cleaning blade 22a arranged in contact with the surface of the photosensitive drum 17. The above-described process cartridge 8 further includes a non-volatile RAM (hereinafter referred to as “NVRAM”) 29. The NVRAM 29 stores the accumulated data of the number of times the process cartridge 8 actually performs printing on the photosensitive drum. The data is stored as data of 17 rotation speeds.
[0030]
In the figure, a main motor 23 disposed at a lower portion of the printer main body 1 drives a paper feed roller 5 via a paper feed clutch 24, drives a registration roller pair 6 via a registration clutch 25, and furthermore, a photosensitive drum. 17, the fixing device 9, the paper discharge roller 11 and the like are driven.
[0031]
Further, a printer control unit (control device) 26 for controlling the entire laser beam printer M is provided in the printer main body 1. As shown in FIG. 2, the printer control unit 26 includes an MPU (microcomputer) 26d as a read / write device including a timer 26a, a ROM 26b, a RAM 26c, and the like, and various input / output control circuits (not shown). . The printer control unit 26 is connected to an external device 28 such as a personal computer via an interface 27 and to an NVRAM 29 in the process cartridge 8 via an interface 30.
[0032]
Next, the operation of the laser beam printer M having the above configuration will be described with reference to the flowchart of FIG.
[0033]
First, it is determined whether or not printing has started (S1), and the MPU 26d reads the drum rotation speed data of the photosensitive drum 17 from the NVRAM 29 incorporated in the process cartridge 8 (S2). Here, the drum rotation number data is compared with the life rotation number (S3). If the drum rotation number data is smaller than the life number data, the printing operation is started (S4). The life is notified to the external device 28 (S14), and the process ends. That is, the drum life rotation speed is written in advance in the NVRAM 29 of the process cartridge 8, and the drum rotation speed data is compared based on this value to detect the drum life.
[0034]
Next, each motor is driven (S5), and after the timer 26a is started (S6), a high voltage in which the AC bias V _AC is superimposed on the DC bias V _DC is applied to the charging roller 19 (S7), and the printing operation is performed. At this time, the drum rotation time is counted by the timer 26a.
[0035]
Next, it is determined whether the printing operation has been completed (S8). If the printing operation is to be continued, the process returns to step S4 to continue the printing operation, and accumulates and counts the number of rotations of the drum. Conversely, when printing is completed, the high voltage applied to the charging roller 19 is turned off (S9), the timer 26a is stopped (S10), and each motor is stopped (S11).
[0036]
As described above, the counted cumulative drum rotational speed data is written into the NVRAM 29 (S12), and the cumulative drum rotational speed data and the drum life data are compared by the MPU 26 (S13).
[0037]
If the cumulative drum rotation speed data is not larger than the life rotation speed, the process returns to step S1, and if it is larger, the MPU 26 notifies the cartridge life (S14) via the external device 28.
[0038]
As described above, in the process cartridge 8 having the charging roller 19, the drum life can be detected by detecting the drum rotation number data at the time of applying a bias to the charging roller 19 during printing as needed. Can be output to the external device 28. As a result, it is possible to prevent the occurrence of a fog image prior to the occurrence of a blank white image, which tends to occur when intermittent printing is continued at a low printing rate, for example. Here, as for the life rotation number previously written in the NVRAM 29 of the process cartridge 8, the guaranteed number of prints of the process cartridge 8 needs to be set to be larger than the total rotation number when bias is applied to the charging roller 19 at the time of intermittent printing.
[0039]
In addition, it is necessary to set the thickness of the photosensitive layer applied to the photosensitive drum 17 at this time so that a fog image is not output even when the photosensitive drum 17 is scraped after the total number of rotations described above. Not even.
<Example 2>
As described in the first embodiment, in the process cartridge 8 having the charging roller 19, the drum rotation speed is written into the NVRAM 29 as needed, and the drum rotation life is detected by comparing the rotation speed with the life rotation speed. By outputting the process cartridge exchange message to the external device 28, the output of the fog image before white dropout is prevented.
[0040]
However, it is known that when the bias applied to the charging roller 19 is obtained by superimposing the AC bias on the DC bias, the drum scraping amount is larger than when only the DC bias is applied. A measure for reducing the drum scraping amount will be described below.
[0041]
FIG. 4 is a flowchart showing the operation of the second embodiment (the same steps as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted). The configuration of the laser beam printer as an example of the image forming apparatus is the same as the configuration of the first embodiment. Example 1 differs in this second embodiment, the time t ₁ at the time of applying a high voltage DC bias by the timer 1 to the charging roller 19, also at the time of applying a bias obtained by superimposing an AC bias on a DC bias the time t ₂ is a point that is counted separately from the timer 2. When the printing operation is started (S4) and each motor is driven (S5), the timer 1 is started (S101), and a high DC bias voltage of the charging roller 19 is applied (S102). When the printing process is started (S103), the timer 2 is started (S104), and the high AC bias of the charging roller 19 is superimposed (S105). The printing process is executed (S106). When the printing process is completed (S107), the AC bias of the charging roller 19 is turned off (S108), and the timer 2 is stopped (S109). If the printing is continued, the process returns to step S103. If the printing is completed, the high-voltage DC of the charging roller 19 is turned off (S110). In step S103, if the waiting time has elapsed without starting the printing process (S111), the high-voltage DC bias of the charging roller 19 is turned off. If the waiting time is not over in step S111, the process returns to step S103.
[0042]
When calculating the cumulative drum rotational speed in Step S 12 in FIG. 4, only the DC bias is applied to the charging roller 19, the time in which the photosensitive drum 17 rotates is applied are superimposed t ₁ -t 2, _AC bias the time is _{t 2.} Here, during the period of t ₁ -t ₂ , since the printing process is not performed during the non-printing process such as development and transfer, the photosensitive drum 17 is rotated only by charging the photosensitive drum 17 only with the DC bias. However, fog toner does not adhere to the photosensitive drum 17 and a good printing process is shown.
[0043]
Therefore, the AC bias is superimposed on the DC bias only in the portion that contributes to the printing process. In addition, for example, in processes such as sheet feeding, sheet discharging, and post-rotation, it is possible to reduce the amount of drum scraping by applying only a DC bias. For this reason, when the thickness of the photosensitive layer of the photosensitive drum 17 is the same as that of the first embodiment, the number of rotations of the drum life is increased. On the other hand, when the film thickness is reduced and set to the same drum life rotation number as in the first embodiment, the coating material for the photosensitive layer of the photosensitive drum 17 is reduced, and the cost of the process cartridge 8 can be reduced.
[0044]
Here, in the above-described embodiment, the cumulative drum rotation speed in step S120 is obtained as follows.
[0045]
In the laser beam printer M shown in FIG. 1, the condition of the process cartridge 8 is not changed and one is a case where only the DC bias is applied to the charging roller 19 and the other is a case where the AC bias is superimposed and applied on the DC bias. When the drum scraping amount was compared with the average value of 10 drums, the drum scraping amount per 1000 sheets was as shown in FIG. That is, it was found that the amount of drum abrasion with only the DC bias was 1/5 or less as compared with the case where the AC bias was superimposed on the DC bias. Therefore, the rotation speed of the drum to which only the DC bias is applied becomes 1/5 when the rotation speed when the AC bias is superimposed on the DC bias is substituted, judging from the scraping amount.
[0046]
Therefore, assuming that the accumulated drum rotation speed is n ₀ , the process speed is v _P , and the drum radius is R,
n ₀ = {(1/5) × (t ₁ −t ₂ ) v _P / 2πR} + {v _P × t ₂ / 2πR}
It becomes.
[0047]
Further, as with the first embodiment, it is necessary to set the number of prints guaranteed for the process cartridge 8 to be larger than n ₁ when the total number of rotations of the drum is n ₁ when performing intermittent printing. There is.
[0048]
As described above, in the second embodiment, the generation of the fog image before the occurrence of white spots can be prevented, and the life of the drum can be increased by reducing the amount of scraping of the drum. As a result, the cost of the process cartridge 8 can be reduced.
<Example 3>
FIG. 6 shows a schematic configuration of a conventional laser beam printer incorporating the process cartridge 110 shown in FIG. Reference numeral 120 denotes an exposure device including a scanner and a semiconductor, 121 denotes a reflection mirror, 122 denotes a fixing device, 123 denotes a registration roller, 124 denotes a paper cassette, 125 denotes a multi-purpose tray (hereinafter, referred to as an “MP tray”), and 126 denotes a face-up. Trays (hereinafter referred to as “FU trays”) 127 are face-down trays (hereinafter referred to as “FD trays”), 128 and 129 are paper feed rollers, 130 is a duplex unit, and 131 is a reversing roller.
[0049]
First, in the case of single-sided printing, the transfer material P supplied from the paper supply cassette 124 or the MP tray 125 is fixed after the toner image formed on the photosensitive drum 101 of the process cartridge 110 is transferred by the transfer roller 105. After being fixed by the container 122, the sheet is discharged onto the FU tray 126 or the FD tray 127.
[0050]
Next, the case of double-sided printing will be described. The transfer material P printed on one side passes through the fixing device 122 and is carried into the duplex unit 130. When the rear end of the transfer material P reaches the reversing roller 131, the reversing roller 131 rotates and is transferred to the registration roller 123. Re-feeded. Then, after printing is performed in the same manner as in single-sided printing, the sheet is discharged to the FU tray 126 or the FD tray 127. Further, 132 is an MPU, 133 is a high-pressure unit, 134 is an interface, 135 is an external device, and 136 is a motor.
[0051]
As described above, when the laser beam printer includes a plurality of paper feed units, a plurality of paper discharge units, and a duplex unit, the printing process is performed via a number of paper path routes (transfer material transport paths). For this reason, when an image is printed using the conventional process cartridge 110, even when the paper path is long and the printing is performed at the specified printing rate, the photosensitive drum 101 may be scraped before the guaranteed number of prints, and a fog image may be output. there were.
[0052]
FIG. 7 illustrates a schematic configuration of a laser beam printer (image forming apparatus) according to a third embodiment that employs a configuration that solves this problem. The laser beam printer M shown in FIG. 6 has an NVRAM 138 incorporated in the process cartridge 110 of the laser beam printer M shown in FIG. 6, and an MPU 137 having a timer 137a, a ROM 137b, and a RAM 137c arranged in the print main body 1 side. It is. The MPU 137 is communicably connected to an external device 135 via an interface 174.
[0053]
In the laser beam printer M having the above-described configuration, printing on the transfer material P is performed via various paper path routes, as in the second embodiment. In these printings, the charging of the photosensitive drum 101 by the charging roller 102 is performed in a state where the AC bias is superimposed on the DC bias when the printing process is actually performed, so that the photosensitive drum 101 is easily scraped. ing. However, in other cases, that is, when the printing process is not actually performed, the process is performed in a state where only the DC bias is applied.
[0054]
As described above, according to the configuration of the third embodiment, even when the print main body 1 has a plurality of paper feeding paths, paper discharging paths, and a duplex unit, the scraping of the photosensitive drum is reduced, and the generation of fog is reduced. Can be prevented.
[0055]
【The invention's effect】
As described above, according to the present invention, data on the total number of rotations of the photoconductor is stored in the nonvolatile RAM in the process cartridge by the control device via the read / write device. This data is updated each time the photoconductor rotates, and is, for example, a parameter that accurately indicates the wear state of the photoconductor. Therefore, when the image forming conditions, for example, the voltage applied to the charging member are set based on the latest data stored in the nonvolatile RAM, the surface of the photoconductor can be charged well. Further, for example, when the image forming apparatus stores the life rotation number of the photoconductor, the data of the total rotation number of the photoconductor stored in the nonvolatile RAM is compared with the life rotation number at the time of image formation. It is possible to prevent the output of a fog image when the number of formed images is large and to output a good image.
[0056]
Further, for example, when the cleaning blade of the cleaning device is arranged in contact with the surface of the photoreceptor and the non-printing process in which the voltage applied to the charging member is only the DC voltage, the AC voltage and the DC voltage are used. The abrasion of the photoconductor surface by the cleaning blade is less than in the printing process in which the voltage is superimposed. Therefore, a correction is made to the rotation speed of the photoconductor during the non-process. Since the wear of the photoconductor is small because the AC voltage is not applied, the correction is made smaller by that amount. By doing so, the total number of rotations of the photoconductor can be grasped as a state closer to actual wear of the photoconductor, and a good image can be formed until the life of the photoconductor reaches its end.
[0057]
As described above, the photoconductor is rotated not only during the printing process but also during the non-printing process. The non-printing process includes the transfer of the transfer material in addition to the transfer of the transfer material in the printing process, and the photosensitive member is rotated during the latter transfer. Therefore, even when an image is formed on the same one transfer material, the longer the transfer material transport length of the transfer material transport path, the higher the number of rotations of the photoconductor. Therefore, the total number of rotations of the photoconductor is corrected according to the transfer material conveyance path used for image formation. Also in this case, similarly to the case where the correction is performed by the applied voltage, the total number of rotations of the photoconductor can be grasped as a state closer to actual wear of the photoconductor,
[Brief description of the drawings]
FIG. 1 is an overall schematic configuration diagram of a laser beam printer according to a first embodiment.
FIG. 2 is a diagram showing a configuration of an MPU and a periphery thereof according to the first embodiment.
FIG. 3 is a flowchart illustrating a printing operation of the laser beam printer according to the first embodiment.
FIG. 4 is a flowchart illustrating a printing operation of the laser beam printer according to the second embodiment.
FIG. 5 is a diagram showing a difference in drum scraping amount due to a difference in voltage applied to a charging roller in the second embodiment.
FIG. 6 is an overall schematic configuration diagram of a conventional laser beam printer.
FIG. 7 is an overall schematic configuration diagram of a laser beam printer according to a third embodiment.
FIG. 8 is a diagram showing a configuration around a photosensitive drum of a conventional laser beam printer.
FIG. 9 is a longitudinal sectional view showing a configuration of a conventional process cartridge.
FIG. 10 is a view showing a state of charging by a conventional charging roller.
FIG. 11 is an overall schematic configuration diagram of a conventional laser beam printer.
[Explanation of symbols]
1. Image forming apparatus main body (print main body)
9 Fixing device 17 Photoconductor (photosensitive drum)
18 Process cartridge 19 Charging member (charging roller)
Reference Signs List 20 developing device 21 transfer charger 22 cleaning device 22a cleaning blade 26 controller (printer controller)
26a Timer 26b ROM
26c RAM
26d read / write device (MPU)
29 Nonvolatile RAM (NVRAM)
M image forming device (laser beam printer)
P transfer material

Claims (1)

A contact charging member for charging the photosensitive member and the photosensitive member on which a toner image is formed on the surface, a process cartridge having a non-volatile memory means for storing data corresponding to the total number of rotations of the photosensitive member, image In an image forming apparatus that is detachably attached to a forming apparatus body and used,
A control unit that updates data corresponding to the total number of rotations of the photoconductor with respect to the nonvolatile storage unit,
During a printing operation, a period during which the photoconductor rotates is a first period in which an AC voltage and a DC voltage are applied to the contact charging member, and a DC voltage is applied to the contact charging member. A second period in which no AC voltage is applied,
The control unit is configured to convert data corresponding to a total rotation number of the photoconductor in the first period and data corresponding to a total rotation number of the photoconductor in the second period from an actual total rotation number of the photoconductor. An image forming method comprising: obtaining data corresponding to the total number of rotations of the photoconductor based on the data corrected so as to reduce the number of rotations; and updating data according to the total number of rotations of the nonvolatile storage unit. apparatus.

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