JP4337319B2 - Image forming apparatus and life detection method of image carrier - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a printer, a copying machine, and a facsimile capable of forming a full-color or black-and-white image using an electrophotographic method and the like, and more specifically, includes a plurality of image forming units. The present invention relates to an image forming apparatus.
[0002]
[Prior art]
In recent years, so-called full-color tandem machines have been proposed in image forming apparatuses such as printers, copiers, and facsimile machines for the purpose of forming color images at high speed and high image quality. As a typical tandem machine, four image forming units of yellow (Y), magenta (M), cyan (C), and black (K) are arranged in parallel with each other, and each of these image forming units. The toner images (yellow, magenta, cyan, black) of each color that are sequentially formed in Step 1 are temporarily transferred onto the intermediate transfer belt in a multiplex manner, and then transferred from the intermediate transfer belt to the transfer paper in a batch. Examples include those that form a full-color or black-and-white (monochrome) image by fixing the toner image formed on the transfer paper.
[0003]
FIG. 12 is a diagram showing an example of such a tandem machine. The image forming apparatus shown in FIG. 12 includes four image forming units 300Y, 300M, 300C, and 300K that form toner images having different colors of yellow, magenta, cyan, and black, and these image forming units 300Y and 300M. , 300C, 300K are arranged in parallel at regular intervals along the horizontal direction. The image forming units 300Y, 300M, 300C, and 300K have substantially the same configuration except that the color of the toner image to be formed is different, and after the surface of the photosensitive drum 301 is uniformly charged by the charging device 302 The exposure device 303 exposes the surface of the photosensitive drum 301 to form an electrostatic latent image corresponding to the image information of each color. The electrostatic latent image formed on the surface of the photosensitive drum 301 is visualized by a developing device 304 of a corresponding color to become a toner image, and this toner image is transferred to an intermediate transfer belt by a charger 305 for primary transfer. Multiple images are sequentially transferred onto 306. The toner remaining on the surface of the photosensitive drum 301 is removed by the cleaning device 307 to prepare for the next image forming process.
[0004]
The intermediate transfer belt 306 is circulated and driven at a speed equal to the rotational speed of the photosensitive drum 301 by a plurality of rollers 308, 309, 310, 311, 312 including a driving roller. The yellow, magenta, cyan, and black toner images transferred in multiple onto the intermediate transfer belt 306 are intermediate at the secondary transfer position (the position of the roller 311) provided below the intermediate transfer belt 306. The secondary transfer roll 313 that is in contact with the surface of the transfer belt 306 is collectively transferred onto the transfer paper 314 that is fed at a predetermined timing to the secondary transfer position. Thereafter, the transfer sheet 314 is conveyed to a fixing device (not shown), and is subjected to fixing processing with heat and pressure by the fixing device, thereby forming a color or monochrome image.
[0005]
Here, as the charging device 302 for charging the surface of the photosensitive drum 301, a non-contact type discharging by a corona charging device has been widely used. However, in order to reduce the generation of ozone and reduce power consumption. In recent years, the contact type has attracted attention. In this contact type, for example, a charging member such as a charging roller or a charging brush is brought into contact with the photosensitive drum 301 that is a member to be charged, and a predetermined charging bias is applied to the surface of the photosensitive drum 301 that is an image carrier. Is charged to a predetermined polarity and potential.
[0006]
As a conventional technique using this contact-type charging member, in order to detect the life of the photoreceptor, the usage time of the photoreceptor is measured by weighting the rotation time of the photoreceptor, the application time of the primary AC high voltage, and the process speed. However, there is a technique for determining the lifetime of the photoconductor in consideration of the influence of each factor on the lifetime of the photoconductor (see, for example, Patent Document 1). In addition, when an AC voltage and a DC voltage are used together for bias application from the charging member, a coefficient for calculating the damage caused by each bias application to the image carrier is determined according to the applied bias component. There is a technique of changing and integrating the damage of the image carrier calculated from this coefficient and the bias application time (for example, Patent Document 2).
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-39690 (page 4-6, FIGS. 1 and 6)
[Patent Document 2]
Japanese Patent Laid-Open No. 10-186972 (page 8-9, FIGS. 1 and 4)
[0008]
[Problems to be solved by the invention]
As described above, when the contact-type charging member is charged by bringing it into contact with an image carrier such as a photosensitive drum, the surface of the image carrier is damaged and worn due to various factors. As a cause of wear of the image carrier, more specifically, friction with a cleaning device that removes toner remaining on the surface of the image carrier, damage due to a charging bias applied from a contact-type charging member, and the like can be given. It is done. In particular, it is known that when an AC voltage is used for applying a charging bias, damage is considerably greater than when a DC voltage is used. This damage to the image carrier due to the charging bias can occur in the same manner even in a non-contact type charging device. When an image is formed on an image carrier that has been worn due to such factors, there is a problem that the image quality deteriorates. For this reason, when the image carrier is worn and the film thickness on the surface becomes a predetermined value or less, it is detected that the life of the image carrier has been reached, and for each process cartridge including the image carrier or the image carrier. It is desirable to exchange.
[0009]
However, it is difficult to accurately detect the life of the image carrier mounted inside the image forming apparatus during the operation of the image forming apparatus. In order to deal with such a problem, for example, by adopting the technique of Reference 1 described above and judging the life of the image carrier from the rotation time of the image carrier, the application time of the bias voltage, and the process speed, the life of the image carrier Although it is effective to a certain extent, this lifetime cannot be detected accurately. In the technique described in the above-mentioned document 2, the wear coefficient is changed according to the applied bias voltage component, and the damage of the image carrier is integrated from this coefficient and the bias application time. An appropriate wear coefficient corresponding to the cycle of the image carrier is not selected, and damage to the image carrier cannot be detected accurately. Further, in Patent Documents 1 and 2 described above, the bias application time is weighted, but the wear amount of the image carrier varies depending on the cycle of the image carrier.
[0010]
The present invention has been made to solve the technical problems as described above, and the object of the present invention is not affected by the use state when the charging bias is applied by the contact-type charging member. The object is to detect the life of the image carrier with higher accuracy.
Another object of the present invention is to provide a system that detects the life of a plurality of image carriers provided in the image forming apparatus according to the usage state and individually detects the life of each image carrier.
[0011]
[Means for Solving the Problems]
For this purpose, the present invention focuses on the use state of the image carrier determined by the voltage application conditions applied to the image carrier and the number of cycles of the image carrier. Furthermore, the inventor of the present invention measured the amount of wear when a voltage was applied to the image carrier with high accuracy, and obtained a highly accurate life factor from the application conditions and the number of cycles. In the present invention, the life of the image carrier is detected with high accuracy based on the life coefficient of the image carrier and the state of use.
That is, the present invention is an image forming apparatus provided with a charger for applying a voltage to an image carrier, and a voltage application condition applied from the charger to the image carrier and a cycle of the image carrier. Use condition grasping means for grasping the number, life coefficient determining means for determining the life coefficient of the image carrier from the application condition grasped by the use condition grasping means and the past use history of the image carrier, and A life integrated amount calculating means for calculating the life of the image carrier based on the life coefficient determined by the life coefficient determining means and the number of cycles of the image carrier;
[0012]
Here, the value of the lifetime coefficient determined by the lifetime coefficient determining means is a value determined from the lifetime integrated amount of the image carrier using the applied voltage applied by the charger as a parameter. The number of cycles grasped by the use state grasping means is grasped from the application time of the voltage applied from the charger to the image carrier, the process speed in the image carrier, and the diameter of the image carrier. The Further, the voltage application condition grasped by the use state grasping means includes at least a case where a voltage obtained by superimposing an AC voltage and a DC voltage is applied and a case where a voltage consisting only of a DC voltage is applied. Further, in this image forming apparatus, the image carrier and the charger are formed into a cartridge and stored in the main body of the image forming apparatus, and storage means for storing past use history information of the image carrier in units of the cartridge. Is further provided. Then, the lifetime integrated amount calculating means calculates the lifetime integrated amount of the image carrier based on the use history information stored in the storage means.
[0013]
The image forming apparatus of the present invention includes an image carrier, a charger that charges the image carrier, a power supply unit that applies a charging bias to the charger according to predetermined application conditions, and the power supply unit. The lifetime coefficient of the image carrier is determined from the charging bias application condition and the past use history of the image carrier, and the lifetime integrated amount of the image carrier is calculated from the use state and the lifetime coefficient of the image carrier. It can be set as the structure provided with the control part.
Here, in this image forming apparatus, the usage state of the image carrier is grasped based on the number of cycles of the image carrier or the charging time of the image carrier by applying a charging bias. In addition, the lifetime coefficient of the image carrier increases steplessly or stepwise according to the lifetime accumulated amount of the image carrier.
[0014]
Furthermore, the present invention provides the following image carrier lifetime detection method in an image forming apparatus including an image carrier to which a charging bias is applied by a charger. The image carrier life detection method includes a step of calculating the number of cycles of the image carrier in the printing operation of the image forming apparatus, a step of reading the past life accumulated amount of the image carrier, and an image carrier from the charger. The step of calculating a life factor from the application condition of the charging bias applied to the body and the accumulated life amount of the read image carrier, and the life in this printing operation based on the cycle number and the life factor of the image carrier Calculating an integrated amount.
[0015]
Here, in this image carrier life detection method, in the step of calculating the lifetime integrated amount, a new lifetime integrated amount is calculated from the past lifetime integrated amount and the calculated lifetime integrated amount in the printing operation. The image carrier life detection method further includes a step of determining the life of the image carrier by comparing the calculated new accumulated life amount with a predetermined threshold.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a diagram showing the overall configuration of an image forming apparatus to which this embodiment is applied, and shows a so-called tandem type digital color printer. An image forming apparatus shown in FIG. 1 includes an image processing system 10 that forms an image corresponding to gradation data of each color, a sheet conveyance system 40 that conveys recording paper (sheet), such as a personal computer or an image reader. An IPS (Image Processing System) 50, which is an image processing system that is connected to a device or the like and performs predetermined image processing on received image data, is provided.
[0017]
The image processing system 10 includes four image forming units 11Y and 11M of yellow (Y), magenta (M), cyan (C), and black (K), which are arranged in parallel at regular intervals in the horizontal direction. , 11C, 11K, a transfer unit 20 for transferring the toner images of the respective colors formed on the photosensitive drums 12 of the image forming units 11Y, 11M, 11C, 11K onto the intermediate transfer belt 21, and the image forming units 11Y, 11M, ROS (Raster Output Scanner) 30 which is an optical system unit for irradiating laser beams to 11C and 11K is provided. Further, the main body 1 is provided with a fixing device 29 for fixing the image on the recording paper (sheet) secondarily transferred by the transfer unit 20 to the recording paper using heat and pressure. Further, toner cartridges 19Y, 19M, 19C, and 19K are provided for supplying toner of each color to the image forming units 11Y, 11M, 11C, and 11K.
[0018]
The transfer unit 20 includes a drive roll 22 that drives an intermediate transfer belt 21 that is an intermediate transfer member, a tension roll 23 that applies a constant tension to the intermediate transfer belt 21, and a secondary transfer of the superimposed toner images of each color onto a recording sheet. For this purpose, a backup roll 24 and a cleaning device 25 for removing residual toner and the like existing on the intermediate transfer belt 21 are provided. The intermediate transfer belt 21 is wound around the drive roll 22, the tension roll 23, and the backup roll 24 with a constant tension, and is rotated by a dedicated drive motor (not shown) having excellent constant speed. The drive roll 22 is circulated at a predetermined speed in the direction of the arrow. As the intermediate transfer belt 21, for example, a belt whose resistance is adjusted with a belt material (rubber or resin) that does not cause charge-up is used. The cleaning device 25 includes a cleaning brush 25a and a cleaning blade 25b, and removes residual toner, paper dust, and the like from the surface of the intermediate transfer belt 21 after the toner image transfer process is completed, and performs the next image forming process. It is comprised so that it may prepare for.
[0019]
In addition to a semiconductor laser and a modulator (not shown), the ROS 30 includes a polygon mirror 31 that deflects and scans laser light (LB-Y, LB-M, LB-C, and LB-K) emitted from the semiconductor laser. In the example shown in FIG. 1, since the ROS 30 is provided below the image forming units 11Y, 11M, 11C, and 11K, there is a risk of contamination due to dropping of toner or the like. Therefore, the ROS 30 is provided with a rectangular parallelepiped frame 32 for sealing each component member, and a glass window 33 through which the laser light (LB-Y, LB-M, LB-C, LB-K) passes is provided. It is provided above the frame 32 so as to enhance the shielding effect together with the scanning exposure.
[0020]
The sheet conveying system 40 is loaded with a recording paper (sheet) on which an image is recorded and fed, a nudger roll 42 that picks up and feeds the recording paper from the paper feeding device 41, and is fed from the nudger roll 42. A feed roll 43 that separates and conveys the recording sheets that have been separated one by one and a conveyance path 44 that conveys the recording sheets separated one by one by the feed roll 43 toward the image transfer unit are provided. Also, a registration roll 45 that conveys the recording paper conveyed through the conveyance path 44 in time toward the secondary transfer position, and a backup roll 24 that is provided at the secondary transfer position and is in pressure contact with the recording paper. And a secondary transfer roll 46 for secondary transfer of the image. Further, a discharge roll 47 for discharging the recording paper on which the toner image is fixed by the fixing device 29 to the outside of the main body 1 and a discharge tray 48 for stacking the recording paper discharged by the discharge roll 47 are provided. In addition, a double-sided conveyance unit 49 is provided that enables double-sided recording by inverting the recording paper fixed by the fixing device 29.
[0021]
Next, the operation of the image forming apparatus shown in FIG. 1 will be described. A color material reflected light image of a document read by a document reading device (not shown) and color material image data formed by a personal computer (not shown) are, for example, R (red), G (green), and B (blue). Each 8-bit reflectance data is input to the IPS 50. In IPS 50, the input reflectance data is subjected to predetermined image processing such as various image editing such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color editing, and moving editing. Is done. The image data that has been subjected to image processing is converted into color material gradation data of four colors of yellow (Y), magenta (M), cyan (C), and black (K), and is output to the ROS 30.
[0022]
In the ROS 30, laser light (LB-Y, LB-M, LB-C, LB-K) emitted from a semiconductor laser (not shown) is converted into f-θ in accordance with input color material gradation data. The light is emitted to the polygon mirror 31 through a lens (not shown). In the polygon mirror 31, the incident laser light is modulated in accordance with gradation data of each color, deflected and scanned, and image forming units 11Y, 11M, 11C, and 11K through an imaging lens and a plurality of mirrors (not shown). The photosensitive drum 12 is irradiated. On the photosensitive drums 12 of the image forming units 11Y, 11M, 11C, and 11K, the charged surface is subjected to scanning exposure to form an electrostatic latent image. The formed electrostatic latent image is developed as a toner image of each color of yellow (Y), magenta (M), cyan (C), and black (K) in each of the image forming units 11Y, 11M, 11C, and 11K. Is done.
[0023]
The toner images formed on the photosensitive drums 12 of the image forming units 11Y, 11M, 11C, and 11K are multiplex-transferred onto an intermediate transfer belt 21 that is an intermediate transfer member. At this time, the black image forming unit 11 </ b> K that forms a black toner image is provided on the most downstream side in the moving direction of the intermediate transfer belt 21, and the black toner image is finally transferred to the intermediate transfer belt 21. Is done.
[0024]
On the other hand, in the sheet conveyance system 40, the nudger roll 42 rotates in accordance with the timing of image formation, and recording paper of a predetermined size is supplied from the paper feeding device 41. The recording sheets separated one by one by the feed roll 43 are conveyed to the registration roll 45 through the conveyance path 44 and are temporarily stopped. Thereafter, the registration roll 45 rotates in accordance with the movement timing of the intermediate transfer belt 21 on which the toner image is formed, and the recording paper is conveyed to the secondary transfer position formed by the backup roll 24 and the secondary transfer roll 46. . On the recording sheet conveyed from the lower side to the upper side at the secondary transfer position, the toner images in which the four colors are multiplexed are sequentially transferred in the sub-scanning direction using a pressing force and a predetermined electric field. The recording paper on which the toner images of the respective colors are transferred is subjected to a fixing process by heat and pressure by the fixing device 29 and then discharged by a discharge roll 47 to a discharge tray 48 provided on the upper portion of the main body 1. Instead of being discharged as it is to the discharge tray 48, the conveyance direction can be switched by a switching gate (not shown), and the recording sheet fixed by the fixing device 29 can be reversed by the duplex conveyance unit 49. After the reversed recording sheet is conveyed to the registration roll 45, an image can be formed on both sides of the recording sheet by forming an image on the other unprinted side by the same flow as described above. Become.
[0025]
Next, the image forming units 11Y, 11M, 11C, and 11K in the image process system 10 will be described in detail.
FIG. 2 is a diagram for explaining the configuration of the image forming units 11Y, 11M, 11C, and 11K. Here, the yellow (Y) image forming unit 11Y and the magenta (M) image forming unit 11M are shown. Has been. The other image forming units 11C and 11K are configured in substantially the same manner.
[0026]
The image forming units 11Y, 11M, 11C, and 11K are charged by a photosensitive drum 12 as an image carrier for supporting a toner image, a charger 13 that charges the photosensitive drum 12 using a charging roll 13a, and a charger 13. , A developing device 14 for developing an electrostatic latent image formed on the photosensitive drum 12 by a developing roller 14a by laser light (LB-Y, LB-M, LB-C, LB-K) from the ROS 30, an intermediate transfer A primary transfer roll 15 that is provided opposite to the photosensitive drum 12 with the belt 21 interposed therebetween and transfers a toner image developed on the photosensitive drum 12 to the intermediate transfer belt 21 by applying a charging bias. A cleaning device 16 for removing residual toner remaining on the photosensitive drum 12 is provided.
[0027]
Next, the cartridge will be described.
FIG. 3 is a view for explaining the cartridge in the present embodiment. In the present embodiment, the photosensitive drum 12, the charger 13, and the cleaning device 16 of each of the image forming units 11Y, 11M, 11C, and 11K are integrated for each color to form a process cartridge 60. Only the process cartridge 60 can be removed from the main body 1 of the image forming apparatus, and only the process cartridge 60 can be attached to the main body 1 so that the user can replace it. These process cartridges 60 can be used by being replaced between the image forming units 11Y, 11M, 11C, and 11K.
[0028]
FIG. 4 is a perspective view of the process cartridge as viewed from another direction. Each process cartridge 60 includes a cartridge memory 61. The cartridge memory 61 includes, for example, a predetermined image forming unit 11Y, 11M, 11C, and 11K such as the number of rotations of the photosensitive drum 12, a high voltage application time, the number of prints, and an accumulated life amount (described later). Each cartridge use history information when the process cartridge 60 is mounted is stored. Since each process cartridge 60 is equipped with a cartridge memory 61, even if the process cartridge 60 is used in a different image forming unit, the process cartridge 60 itself can display its own usage history information. Can be saved. As a result, the correct lifetime can be determined for each process cartridge 60.
[0029]
Next, drive control in the image forming apparatus will be described.
FIG. 5 is a diagram for explaining drive control of the image forming apparatus to which the exemplary embodiment is applied. Based on the image signal subjected to the image processing by the IPS 50, the CPU (not shown) of the control circuit 100 executes the processing according to the program stored in the ROM (not shown). The control circuit 100 serves as a drive system such as a secondary transfer roll 46, a fixing device 29, a sheet conveying system 40, a main motor 101 that drives the developing device 14 (14K) in the black image forming unit 11K, and the like, and an intermediate portion of the transfer unit 20. An intermediate transfer member driving motor 102 for driving the transfer belt 21 and the like, and a photosensitive member for driving the photosensitive drum 12 (12Y, 12M, 12K) in the color image forming units 11Y, 11M, 11C except for the black image forming unit 11K. Development in the driving motor 103, the black photosensitive member driving motor 104 that drives the photosensitive drum 12 (12K) in the black image forming unit 11K, and the color image forming units 11Y, 11M, and 11C other than the black image forming unit 11K. The developing device drive motor 105 that drives the device 14 (14Y, 14M, 14C) is controlled. The control circuit 100 controls a clutch 111 that is connected to the main motor 101 and switches the driving of the sheet conveying system 40, and a clutch 112 that is connected to the main motor 101 and switches the developing device 14 (14K) in the black image forming unit 11K. is doing. The control circuit 100 controls the operation of these various motors and clutches, thereby timing the respective portions in the image forming apparatus, and enables the image formation on the recording paper by the above-described operation.
[0030]
As described above, in the present embodiment, a part of the image forming units 11Y, 11M, 11C, and 11K is made into a cartridge, and usage history information is stored in the cartridge memory 61 provided in each process cartridge 60. Yes. For example, if the cartridges provided in the image forming units 11Y, 11M, 11C, and 11K are the first cartridge to the fourth cartridge, the control circuit 100 reads the use history information from the cartridge memory 61 of these process cartridges 60, Based on the read usage history information, the process forming conditions can be individually changed for each of the image forming units 11Y, 11M, 11C, and 11K. Further, the control circuit 100 also performs a work of writing new usage history information to the cartridge memory 61 of each process cartridge 60.
[0031]
FIG. 6 is a diagram for explaining control of the image forming apparatus excluding drive control. The control circuit 100 controls a high voltage unit (HVPS) 120, and the high voltage unit 120 applies a charging bias to the charger 13 (13Y, 13M, 13C, 13K). . Here, description of the developing bias applied from the high voltage unit 120 to the developing device 14 is omitted. Also connected to the control circuit 100 is a control panel 140 that includes various buttons for operating the image forming apparatus or operation means (not shown) such as a touch panel and display means (not shown) such as a display. Yes. The control circuit 100 operates as a function of a CPU (not shown) according to each information and program stored in a ROM (not shown).
The control circuit 100 is provided with a RAM (not shown) that holds various information used when the CPU operates.
[0032]
Further, the control circuit 100 is connected to a cartridge memory 61 (61Y, 61M, 61C, 61K) mounted on the process cartridge 60 constituting each of the image forming units 11Y, 11M, 11C, 11K. Further, it is connected to a main body memory 130 provided in the main body 1 of the image forming apparatus. The cartridge memory 61 stores past use history information in each process cartridge 60 as described above. The main body memory 130 also stores information such as the number of prints of a recording sheet counted by a PV (Page Volume) counter, the number of rotations of the photosensitive drum 12 counted by a cycle counter, and the lifetime accumulated amount of the photosensitive drum 12. Etc. are stored. In the control circuit 100, control is performed on the high voltage unit 120 and the like based on each information obtained from the cartridge memory 61 (61Y, 61M, 61C, 61K) and the main body memory 130, and based on an instruction from the control circuit 100. Thus, the use history information and the like of the cartridge memory 61 (61Y, 61M, 61C, 61K) are updated.
[0033]
The control circuit 100 controls the high voltage unit 120 to superimpose a DC voltage component and an AC voltage component including a vibration component (alternating current component) on the DC voltage component, thereby charging the charger 13 (13Y, 13M, 13C, 13K). A charging bias is applied to. As the DC voltage used for the charging bias, for example, Vdc = (− 750) V is applied as a constant voltage. The AC voltage is a sine wave waveform that can be uniformly charged as compared with the DC voltage, and at a process speed of 165 mm / sec (in the full color mode), for example, the frequency f = 1306 Hz and the voltage value Vpp = 1. It is controlled to be 9 kV. In this case, the photosensitive drum 12 is applied with a charging bias in which an AC voltage and a DC voltage are superimposed or a charging bias with only a DC voltage. In the monochrome mode, when the process speed of the entire image forming apparatus is 165 mm / sec, the process speed of the non-image forming engine (color image forming units 11Y, 11M, and 11C) is, for example, 52 mm / sec. Become. In this case, the color photosensitive drums 12 (12Y, 12M, and 12C) are idle in a state where no charging bias is applied. As described above, in a full-color tandem machine, the charging bias (application condition) applied to the photosensitive drum 12 differs depending on the image to be formed.
[0034]
FIG. 7 is a diagram for explaining functions realized in the control circuit 100 according to the present embodiment. The functions shown in the block diagram of FIG. 7 are software blocks implemented in the CPU of the control circuit 100. The control circuit 100 detects the number of drum cycles of the photosensitive drum 12 corresponding to the voltage application condition (charging condition) for each charger 13 (one rotation of the photosensitive drum 12 is one cycle). A detection unit 201, a life accumulation amount reading unit 202 that reads a life accumulation amount (life accumulation amount or wear amount based on a past use history) stored in the cartridge memory 61 of the process cartridge 60 until the end of the previous printing operation; A life coefficient calculation unit 203 that calculates the life coefficient of the photosensitive drum 12 based on the voltage application condition detected by the charging cycle detection unit 201, the number of drum cycles, and the past use history information (life accumulation amount); Life integrated amount calculation for calculating the life integrated amount from the number of drum cycles and the life coefficient calculated by the life coefficient calculating unit 203 It includes a 204, and a lifetime cumulative amount writing unit 205 to store the lifetime accumulated amount calculated by the lifetime accumulated amount calculating section 204 in the cartridge memory 61 of the process cartridge 60. Further, the control circuit 100 compares the life information read unit 206 that reads life information used as a threshold for judging the life of the photosensitive drum 12 with the life information stored in the cartridge memory 61 and the life information. It further includes an amount comparison unit 207 and a life warning unit 208 that issues a warning if necessary according to the comparison result in the life accumulated amount comparison unit 207.
[0035]
Here, the charging cycle detection unit 201 described above is a charging bias component (when an AC voltage and a DC voltage are applied in a superimposed manner, when only a DC voltage is applied, when no charging bias is applied), that is, a charging bias. The number of drum cycles of the photosensitive drum 12 is detected with high accuracy for each application condition. That is, the control circuit 100 functions as a use state grasping means for grasping the application condition of the charging bias and grasping the number of drum cycles of the photosensitive drum 12 according to the application condition. Further, the life coefficient calculation unit 203 as a life coefficient determining means is configured to detect the photosensitive drum from the voltage application condition and the past usage history of the photosensitive drum 12 (amount of wear according to the number of drum cycles of the photosensitive drum 12). A wear coefficient of 12 is calculated by calculation. Further, the lifetime integrated amount calculation unit 204 as the lifetime integrated amount calculating means calculates the lifetime integrated amount by the printing operation by calculation according to the formula described later.
[0036]
Incidentally, as described above, the wear amount of the photosensitive drum 12 varies depending on the charging bias application condition, that is, the usage state of the photosensitive drum 12. In the following, FIG. 8 shows experimental results regarding the relationship between the usage state of the photosensitive drum 12 and the wear amount.
FIG. 8 is a diagram showing the relationship between the number of drum cycles of the photosensitive drum 12 and the wear amount of the photosensitive drum 12 in the present embodiment. Here, in FIG. 8, the horizontal axis indicates the number of drum cycles [kcycle] of the photosensitive drum 12, and the vertical axis indicates the wear amount [μm] of the photosensitive drum 12. As the charging bias application condition for the charger 13, a solid line indicates a case where a charging bias in which an AC voltage and a DC voltage are superimposed is applied, a broken line indicates a case where only a DC voltage is applied as a charging bias, and a two-dot chain line Indicates a case where no charging bias is applied. Here, the correlation between the number of drum cycles of the photosensitive drum 12 and the wear amount using the applied voltage due to the charging bias as a parameter will be described.
[0037]
From the data shown in FIG. 8, the rate of increase in the amount of wear of the photosensitive drum 12 tends to increase as the number of drum cycles increases, regardless of the usage conditions. is there. In other words, it can be said that the wear amount of the photosensitive drum 12 increases approximately to a quadratic function as the number of drum cycles increases. In addition, the rate of increase in the amount of wear is greatest when a charging bias in which an AC voltage and a DC voltage are superimposed is applied, and then is large when a charging bias with only a DC voltage is applied. The increase rate of the wear amount becomes the smallest when the photosensitive drum 12 is idly rotated without applying the charging bias, but the number of drum cycles of the photosensitive drum 12 is not applied even when the charging bias is not applied. Depending on the wear, a predetermined amount is worn. A wear coefficient for calculating the life of the photosensitive drum 12 is derived from the more accurate relationship between the number of drum cycles and the wear amount obtained in this way. Conventionally, in deriving the wear coefficient, the wear amount is assumed to increase linearly (substantially linearly) according to the charging bias application time under any use condition. On the other hand, the present inventor can derive a more accurate wear coefficient by measuring the relationship between the number of drum cycles and the amount of wear with high accuracy, thereby reducing the life of the photosensitive drum 12. It becomes possible to calculate with higher accuracy.
[0038]
As a result of intensive studies by the present inventor, it was possible to derive the lifetime coefficient of the photosensitive drum 12 based on the experimental result data shown in FIG. FIG. 9 is a diagram showing a correlation between the accumulated life amount of the photosensitive drum 12 and the lifetime coefficient of the photosensitive drum 12. In FIG. 9, the horizontal axis represents the accumulated life amount (wear amount [μm]) of the photosensitive drum 12, and the vertical axis represents the lifetime coefficient of the photosensitive drum 12. Further, in the figure, the solid line indicates the life coefficient R1 of the photosensitive drum 12 when a charging bias in which an AC voltage and a DC voltage are superimposed is applied, and the broken line indicates the photosensitivity when only the DC voltage is applied as a charging bias. The life coefficient R2 and the two-dot chain line of the body drum 12 indicate the life coefficient R3 when no charging bias is applied.
[0039]
As shown in FIG. 9, the life coefficient R1 derived from the correlation between the number of drum cycles and the wear amount shown in FIG. 8 is about 0.05 when the life accumulated amount is 0, depending on the life accumulated amount, that is, the usage history. For example, when the wear amount is 16 [μm], it can be set to about 0.08. The life coefficient R2 can be about 0.02 when the life accumulated amount is 0, and can be about 0.035 when the wear amount as the life accumulated amount is 16 [μm]. Further, the life coefficient R3 can be about 0.005 when the life accumulated amount is 0, and can be about 0.009 when the wear amount as the life accumulated amount is 16 [μm]. Thus, these life coefficients R1, R2, and R3 can be set so as to increase linearly (steplessly) according to the accumulated life amount.
[0040]
Further, based on the experimental result data of FIG. 8, the life coefficient of the photosensitive drum 12 can be set as shown in FIG. FIG. 10 is a diagram showing the correlation between the accumulated life amount of the photosensitive drum 12 and the lifetime coefficient of the photosensitive drum 12. The line types indicating the horizontal and vertical axes in FIG. 10 and the life coefficients R1, R2, and R3 are the same as those shown in FIG. As shown in FIG. 10, the life coefficient R1 is about 0.05 when the life accumulated amount (wear amount [μm]) is 0, and is about every 4 [μm] wear (according to the life accumulated amount). It increases by about 0.01 and can be set to about 0.08 when the wear amount as the accumulated life amount is 16 [μm]. The life coefficient R2 is about 0.020 when the life accumulated amount is 0, and increases by about 0.005 for every wear of about 4 [μm], and the wear amount as the life accumulated amount is 16 [μm]. In this case, it can be about 0.035. Further, the life coefficient R3 is about 0.0050 when the life accumulated amount is 0, and increases by about 0.0013 for every wear of about 4 [μm], and the wear amount as the life accumulated amount is 16 [μm]. In this case, it can be about 0.0090. As described above, these life factors R1, R2, and R3 can be set so as to increase stepwise according to the number of drum cycles.
[0041]
9 and 10 show the case where the life coefficients R1, R2, and R3 are obtained from the relationship between the life accumulated amount and the wear amount using the voltage application condition as a parameter. A table corresponding to each reading value of the quantity and the life coefficient may be provided, and the life coefficient may be obtained based on this table. In the above description, the life coefficients R1, R2, and R3 are obtained according to the accumulated life amount. However, the life coefficient may be obtained based on the number of drum cycles and the charging time instead of the accumulated life amount. I do not care.
[0042]
In the present embodiment, the lifetime integrated amount can be derived based on the lifetime coefficient obtained as described above.
Here, the accumulated life amount at the end of the previous printing operation is B, the number of drum cycles when the charging bias is applied by superimposing the AC voltage and the DC voltage is C1, the life coefficient in this case is R1, and only the DC voltage is used. The number of drum cycles when the charging bias is applied is C2, the life factor in this case is R2, the number of drum cycles when the photosensitive drum 12 is idle without applying the charging bias is C3, and the life factor in this case is Assuming R3, the accumulated life amount A is
A = B + (R1 × C1 + R2 × C2 + R3 × C3)
It becomes.
If the lifetime integrated amount is calculated using such an expression, it is possible to cope with the use state regardless of the use state of the photosensitive drum 12.
[0043]
FIG. 11 is a flowchart showing processing executed by the control circuit 100 in accordance with the usage state of the photosensitive drum 12. When a certain printing operation is performed in the image forming apparatus, the control circuit 100 recognizes that this printing operation has been completed (step 1101). Then, in the charging cycle detection unit 201, the charging bias application condition (the usage state of the photosensitive drum 12) is determined from the charging bias application time, the process speed, and the diameter of the photosensitive drum 12 in the image forming process of this printing operation ( The number of drum cycles (C1, C2, C3) is calculated for each AC voltage and DC voltage superimposed (DC voltage only, no voltage applied) (step 1102). Instead of calculating the number of drum cycles by the charging cycle detection unit 201, the number of drum cycles of the photosensitive drum 12 may be detected using a sensor or the like for each charging bias application condition.
[0044]
Next, the accumulated life amount reading unit 202 reads the accumulated life amount B from the cartridge memory 61 of the process cartridge 60 until the end of the previous printing operation (step 1103). Then, the life coefficient (R1, R2, R3) in each usage state of the photosensitive drum 12 shown in FIGS. 9 and 10 is determined from the life accumulated amount B and the charging bias application condition read by the life coefficient calculation unit 203. Is calculated (step 1104). The number of drum cycles (C1, C2, C3) calculated in step 1102, the life accumulated amount B read in step 1103, and the life coefficient (R1, R2, R3) calculated in step 1104 are, for example, a control circuit 100 RAM or the main body memory 130.
[0045]
Then, in the accumulated lifetime calculation unit 204, the number of drum cycles (C1, C2, C3), the lifetime coefficient (R1, R2, R3), and the accumulated lifetime B held in the RAM are used, and based on the above formula. Thus, a new accumulated life amount A at the end of the printing operation in step 1101 is calculated (step 1105). The accumulated life amount A calculated in step 1105 is held in the RAM and written to the cartridge memory 61 of the process cartridge 60 by the accumulated life amount writing unit 205 (step 1106). The written lifetime integrated amount A is read as the lifetime integrated amount B until the end of the immediately preceding printing operation when it is read by the lifetime integrated amount reading unit 202 in the subsequent processing.
[0046]
Further, the life information reading unit 206 reads the life information (Y, Z) from the cartridge memory 61 of the process cartridge 60 or the ROM of the control circuit 100 (step 1107), and this life information (Y, Z) is stored in the RAM. Retained. Here, the lifetime information Y is a threshold value for notifying the user that the lifetime of the photosensitive drum 12 is approaching and urging replacement. The lifetime information Z is a threshold value for the lifetime of the photosensitive drum 12. The magnitudes of these thresholds are Y <Z. Then, the lifetime integrated amount comparison unit 207 determines whether or not the value of the lifetime integrated amount A is smaller than the value of the lifetime information Y (step 1108). If it is determined in step 1108 that the value of the accumulated lifetime A is small, it is determined that the lifetime of the photosensitive drum 12 has not yet approached. In step 1101, the subsequent printing operation is recognized. Wait until done.
[0047]
If it is determined in step 1108 that the value of the lifetime integrated amount A is large, the lifetime integrated amount comparison unit 207 further determines whether or not the value of the lifetime integrated amount A is smaller than the value of the lifetime information Z. Is determined (step 1109). When it is determined in step 1109 that the value of the accumulated lifetime A is small, the lifetime warning unit 208 displays a message prompting the replacement of the photosensitive drum 12 on, for example, the display means provided in the control panel 140. Then, a warning is given to the user (step 1110). Here, after the warning is displayed in step 1110, the process waits in step 1101 until the subsequent printing operation is recognized.
[0048]
If it is determined in step 1109 that the value of the accumulated life amount A is large, the life warning unit 208 displays a warning message indicating that the life of the photosensitive drum 12 is reached on the display means of the control panel 140. Subsequent printing operations are prohibited (step 1111). After the processing of step 1111 is performed, the printing operation with the process cartridge 60 in which the photosensitive drum 12 determined to have a lifetime is stored is prohibited. For example, when the life of the color photoconductor drums 12 (12Y, 12M, 12C) is reached, the image forming process in the full color mode is prohibited, and when the life of the black photoconductor drum 12 is reached, Further, the image forming process in the monochrome mode is prohibited.
[0049]
In the flowchart shown in FIG. 11, the case where the process is started from the time when the printing operation is completed is illustrated, but it is also possible to calculate the accumulated life amount even in the middle of the printing operation and indicate each warning. In the above, the case where processing is performed for each print operation has been illustrated. However, for example, the lifetime integrated amount may be calculated when the image forming apparatus is activated or when the image forming apparatus is restored from the power saving mode.
[0050]
As described above, in this embodiment, the wear coefficient corresponding to the use state of the image carrier is obtained, and the life of the image carrier is detected from the wear coefficient and the number of drum cycles. More specifically, the charging is performed according to the charging bias component applied to the image carrier (superimposition of AC voltage and DC voltage, only DC voltage, no voltage applied). Then, damage to the image carrier by each charging bias, that is, wear of the image carrier (usage history in the past) is accurately measured. The life of the image carrier is more accurately detected based on the wear coefficient and the number of drum cycles obtained from the measurement result. As a result, even when the usage state of the image carrier changes in various ways, the life of the image carrier can be grasped more accurately and easily. Then, by replacing the image carrier that has reached the end of its life, it is possible to suppress adverse effects on the formation of the electrostatic latent image on the image carrier. By doing so, it is possible to suppress deterioration in image quality on the recording paper due to the life of the image carrier.
[0051]
In the present embodiment, the life is detected according to the use state of the image carrier for each process cartridge. More specifically, the life of the image carrier is detected based on the charging bias application time, process speed, and diameter of the image carrier when printing is performed using the process cartridge. Since the accumulated lifetime is stored in a cartridge memory provided in the process cartridge, the lifetime can be accurately detected even when the process cartridge is replaced with another position. By detecting the life of each cartridge in this way, only the cartridge that has reached the end of life can be replaced, so that the operating cost of the image forming apparatus can be reduced.
[0052]
【The invention's effect】
As described above, according to the present invention, the life of the image carrier can be detected with higher accuracy without being affected by the use state when the charging bias is applied by the contact-type charging member.
In addition, according to the present invention, it is possible to provide a system for detecting the lifetime according to the use state of a plurality of image carriers provided in the image forming apparatus and individually detecting the lifetime of each image carrier. it can.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an overall configuration of an image forming apparatus to which the exemplary embodiment is applied.
FIG. 2 is a diagram for explaining a configuration of an image forming unit.
FIG. 3 is a view for explaining a cartridge in the present embodiment.
FIG. 4 is a perspective view of the process cartridge according to the present embodiment as viewed from another direction.
FIG. 5 is a diagram for describing drive control of an image forming apparatus to which the exemplary embodiment is applied.
FIG. 6 is a diagram for explaining control of the image forming apparatus excluding drive control.
FIG. 7 is a diagram for explaining functions realized in a control circuit in the present embodiment;
FIG. 8 is a diagram illustrating a relationship between the number of cycles of the photosensitive drum and the wear amount of the photosensitive drum.
FIG. 9 is a diagram showing the relationship between the accumulated amount of life of the photosensitive drum and the lifetime coefficient of the photosensitive drum.
FIG. 10 is a diagram showing another relationship between the accumulated life amount of the photosensitive drum and the lifetime coefficient of the photosensitive drum.
FIG. 11 is a flowchart illustrating processing executed by a control circuit in accordance with the usage state of the photosensitive drum.
FIG. 12 is a diagram showing an example of a tandem machine as a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Main body, 10 ... Image process system, 11Y, 11M, 11C, 11K ... Image forming unit, 12 ... Photosensitive drum, 13 ... Charger, 14 ... Developer, 14a ... Developing roll, 15 ... Primary transfer roll, 16 DESCRIPTION OF SYMBOLS ... Cleaning device, 20 ... Transfer unit, 21 ... Intermediate transfer belt, 30 ... ROS, 40 ... Sheet conveyance system, 50 ... IPS (Image Processing System), 60 ... Process cartridge, 61 ... Cartridge memory, 100 ... Control circuit, 120 DESCRIPTION OF SYMBOLS ... High voltage unit, 130 ... Main body memory, 140 ... Control panel, 201 ... Charging cycle detection part, 202 ... Life integrated amount reading part, 203 ... Life coefficient calculating part, 204 ... Life integrated amount calculating part, 205 ... Life integrated amount writing 206, life information reading unit, 207 life accumulated amount comparison unit, 208 life warning unit

Claims (10)

An image forming apparatus including a charger that applies a voltage to an image carrier,
The application of the voltage applied from the charger to the image carrier according to application conditions including a case where a voltage obtained by superimposing at least an AC voltage and a DC voltage and a case where a voltage consisting only of a DC voltage is applied. Use state grasping means for grasping conditions and the number of cycles of the image carrier;
Life for warning according to a life integrated value obtained by integrating values based on a life coefficient for each application condition and the number of cycles of the image carrier in the application condition grasped by the use state grasping means Warning means,
Life coefficient determining means for determining the life coefficient of the image carrier for each of the application conditions based on a cumulative use value obtained by integrating values related to the number of cycles of the image carrier in the past. An image forming apparatus. The number of cycles grasped by the use state grasping means is
2. The method according to claim 1, wherein the voltage is applied to the image carrier from the charger, the process speed of the image carrier, and the diameter of the image carrier. 3. Image forming apparatus. The image carrier and the charger are formed into a cartridge and stored in the apparatus main body, and further includes storage means for storing information on the accumulated usage value of the image carrier in the past for each cartridge. The image forming apparatus according to claim 1. An image carrier;
A charger for charging the image carrier;
A power supply unit that applies a voltage to the charger according to application conditions including a case where a voltage obtained by superimposing at least an AC voltage and a DC voltage and a case where a voltage consisting only of a DC voltage is applied;
A life coefficient is determined for each of the application conditions based on a use integrated value obtained by integrating values related to the number of cycles of the image carrier in the past, and the life coefficient for each of the application conditions and the image in the application conditions are determined. An image forming apparatus comprising: a control unit that calculates a lifetime integrated value by adding values based on the number of cycles of the carrier . 5. The image formation according to claim 4 , wherein the value related to the number of cycles of the image carrier is determined based on the number of cycles of the image carrier or a charging time of the image carrier by the charger. apparatus. The image forming apparatus according to claim 4 , wherein the life coefficient of the image carrier increases steplessly or stepwise according to the use integrated value of the image carrier. The image carrier and the charger are formed into a cartridge and housed in the apparatus main body, and further includes a cartridge memory that stores information on the accumulated lifetime value of the image carrier in the past for each cartridge.
The controller is
The image forming apparatus according to claim 4 , wherein the lifetime integrated value is calculated based on information on the lifetime integrated value in the past stored in the cartridge memory. In an image forming apparatus, an image bearing member to which a voltage is applied according to application conditions including a case where a voltage obtained by superimposing at least an AC voltage and a DC voltage and a case where a voltage consisting only of a DC voltage is applied are applied by a charger. A life detection method,
Calculating the number of cycles of the image carrier in the printing operation of the image forming apparatus;
Reading a lifetime integrated value obtained by integrating a value based on a lifetime coefficient for each application condition and the number of cycles of the image carrier in the application condition ;
Calculating a lifetime coefficient from the application condition of the voltage applied to the image carrier from the charger and a lifetime integrated value in the past of the read image carrier;
A method for detecting a lifetime of an image carrier, comprising: calculating a lifetime integrated value in the printing operation based on the number of cycles of the image carrier and the lifetime coefficient. In the step of calculating the lifetime integrated value ,
9. The method according to claim 8 , wherein a new lifetime integrated value is calculated from the lifetime integrated value in the past and the calculated lifetime integrated value in the printing operation. 9. The method according to claim 8 , further comprising a step of comparing the calculated new lifetime integrated value with a threshold set in accordance with the degree of deterioration of the image carrier. .

Images