JP2018077352A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can accurately predict the amount of shaving of a photosensitive layer formed on an image carrier irrespective of the usage state to accurately extend the life of the image carrier.SOLUTION: An image forming apparatus comprises: an image carrier; a transfer member; a control part; and a notification device. The image carrier has a photosensitive layer formed on its surface. The transfer member is arranged to be in contact with the image carrier and transfers a toner image formed on the image carrier to a recording medium. The control part determines the time to replace the image carrier on the basis of the amount of shaving of the photosensitive layer. The notification device notifies a user of the time to replace the image carrier determined by the control part. The control part predicts the amount of shaving of the photosensitive layer according to at least one of the size and the state of the surface of the recording medium, and when the predicted amount of shaving becomes equal to or larger than a predetermined threshold, performs notification for urging replacement of the image carrier by using the notification device.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a laser printer, and a facsimile, and more particularly to a method for accurately detecting the life of a photosensitive drum that is a replaceable member.

  In an image forming apparatus using an electrophotographic system such as a copying machine, a printer, a facsimile, etc., a powdery developer (toner) is mainly used, and a photosensitive layer on the surface of a photosensitive drum (image carrier) is predetermined by a charging device. After charging to a surface potential (same polarity as the charging polarity of the toner), an electrostatic latent image is formed on the photosensitive drum by the exposure device. Then, the formed electrostatic latent image is visualized with toner in the developing device, and the toner image is recorded on a sheet (recording nip) that passes through the nip portion (transfer nip portion) between the photosensitive drum and the transfer member in contact with the photosensitive drum. Generally, a process of performing a fixing process after transfer onto a medium) is performed. At this time, the transfer process of the toner image onto the paper is performed in a state where a transfer voltage or transfer current having a polarity opposite to the charging polarity of the toner is applied to the transfer member.

  By the way, in the case of a photosensitive drum having an organic photosensitive layer (OPC), the photosensitive layer may be worn and thinned due to durability, and the surface potential may be lowered. Specifically, the photosensitive layer is scraped and thinned by friction between the photosensitive drum and a member such as a cleaning blade that contacts the photosensitive drum. When the surface potential of the photosensitive drum decreases, problems such as fogging occur.

  In recent years, the life of photoconductor units has been extended, and a photoconductive drum having an organic photoconductive layer having a durable life of 100,000 sheets or more has been developed. In order to extend the lifetime, the wear resistance of the organic photosensitive layer is being improved, but studies are being made to use it until the photosensitive layer becomes thinner than before. When used in a range where the amount of abrasion of the photosensitive layer is large, it is necessary to improve the accuracy of predicting the amount of abrasion of the photosensitive layer and to predict uneven wear of the photosensitive layer.

  Accordingly, various methods for accurately detecting the amount of abrasion of the photosensitive layer have been proposed. For example, Patent Document 1 discloses an image forming apparatus that reduces the transfer bias in accordance with the amount of abrasion of the photosensitive layer. It is described that a value predetermined according to the cumulative number of printed sheets or the cumulative driving time of the photosensitive drum is used as a predetermined value according to the wear amount of the layer.

JP 2014-2225014 A

  However, in the method of Patent Document 1, only the cumulative number of printed sheets or the cumulative driving time of the photosensitive drum is considered as a value corresponding to the amount of wear of the photosensitive layer, and the amount of abrasion of the photosensitive layer cannot be accurately predicted. was there.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention provides an image forming apparatus capable of accurately predicting the abrasion amount of a photosensitive layer formed on an image carrier regardless of the use state and accurately reporting the life of the image carrier. For the purpose.

  In order to achieve the above object, a first configuration of the present invention is an image forming apparatus including an image carrier, a transfer member, a control unit, and a notification device. A photosensitive layer is formed on the surface of the image carrier. The transfer member is disposed so as to come into contact with the image carrier, and transfers the toner image formed on the image carrier to a recording medium. The control unit determines the replacement time of the image carrier based on the amount of abrasion of the photosensitive layer. The notification device notifies the replacement time of the image carrier determined by the control unit. The control unit predicts the amount of abrasion of the photosensitive layer according to at least one of the size and surface state of the recording medium, and replaces the image carrier using a notification device when the estimated amount of abrasion exceeds a predetermined threshold. A notification that prompts

  According to the first configuration of the present invention, the replacement time of the image carrier is accurately determined based on the abrasion amount of the photosensitive layer calculated according to at least one of the size and the surface state of the recording medium. Therefore, it is possible to replace the image carrier at an appropriate time according to the service life of the image carrier that can maintain good image quality.

1 is a schematic diagram illustrating an overall configuration of an image forming apparatus 100 according to an embodiment of the present invention. Partial enlarged view of the periphery of the image forming portion P in FIG. Block diagram showing a control path of the image forming apparatus 100 A graph showing the transition of the layer thickness of the photosensitive layer 1b in the rotation axis direction of the photosensitive drum 1 when a small-size sheet 18 is passed. The graph which shows transition of the layer thickness of the photosensitive layer 1b in the paper passing area | region of the photosensitive drum 1, and a non-paper passing area | region. 7 is a flowchart illustrating an example of notification control of the replacement timing of the photosensitive drum 1 based on the maximum scraping amount Smax of the photosensitive layer 1b calculated in the image forming apparatus 100 of the first embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an overall configuration of an image forming apparatus 100 according to an embodiment of the present invention, and FIG. 2 is a partially enlarged view around an image forming unit P in FIG. In the main body of the image forming apparatus (for example, a monochrome printer) 100, an image forming portion P that forms a monochrome image by each process of charging, exposure, development, and transfer is disposed.

  In the image forming portion P, along the rotation direction of the photosensitive drum 1 (counterclockwise direction in FIG. 1), the charging device 2, the exposure device 3, the developing device 4, the transfer roller 5, the cleaning device 6, and the charge eliminating device. 7 is disposed. In the image forming unit P, the image forming process for the photosensitive drum 1 is executed while rotating the photosensitive drum 1 in the counterclockwise direction in FIG.

  The photosensitive drum 1 is formed by laminating a photosensitive layer 1b on an outer peripheral surface of, for example, an aluminum drum base tube 1a, and the charging device 2 charges the photosensitive layer 1b. Then, an electrostatic latent image in which charging is attenuated is formed on the surface of the photosensitive layer 1b that has received a light beam from the exposure apparatus 3 described later. In the present embodiment, an organic photosensitive layer (OPC) that generates a high-resolution image with little generation of ozone during charging is used as the photosensitive layer 1b.

  The charging device 2 uniformly charges the surface of the photosensitive drum 1. In the present embodiment, a scorotron charging type charging device that includes a grid between the corona wire and the photosensitive drum 1 and discharges by applying a high voltage to the grid is used. The exposure device 3 irradiates the photosensitive drum 1 with a light beam based on the image data, and forms an electrostatic latent image on the surface of the photosensitive drum 1.

  The transfer roller 5 transfers the toner image formed on the surface of the photosensitive drum 1 onto the paper 18 that is conveyed through the paper conveyance path 11. The cleaning device 6 includes a cleaning blade 20 that makes line contact with the longitudinal direction of the photosensitive drum 1, and a recovery spiral 21 that discharges waste toner scraped off from the surface of the photosensitive drum 1 by the cleaning blade 20. After the image is transferred to the paper, residual toner on the surface of the photosensitive drum 1 is removed. The static eliminator 7 irradiates the surface of the photosensitive drum 1 with static elimination light to remove residual charges.

  When performing a printing operation, image data transmitted from a host device such as a personal computer (hereinafter referred to as a personal computer) is converted into an image signal. On the other hand, in the image forming unit P, the photosensitive drum 1 that rotates counterclockwise in the drawing is uniformly charged by the charging device 2, and the exposure device 3 emits a light beam onto the photosensitive drum 1 based on the image signal. By irradiating, an electrostatic latent image based on the image data is formed on the surface of the photosensitive drum 1. Thereafter, the toner carried on the developing roller 4a of the developing device 4 is attached to the electrostatic latent image to form a toner image. The toner is supplied to the developing device 4 from the toner container 8.

  The sheet 18 is conveyed from the sheet storage unit 10 through the sheet conveyance path 11 and the registration roller pair 13 at a predetermined timing toward the image forming unit P on which the toner image is formed as described above. The toner image on the surface of the photosensitive drum 1 is transferred onto a sheet at a transfer nip N between the transfer roller 5 and the transfer roller 5. Then, the sheet 18 on which the toner image is transferred is separated from the photosensitive drum 1, conveyed to the fixing unit 9, and heated and pressed to fix the toner image on the sheet 18. The sheet 18 that has passed through the fixing unit 9 is distributed in the conveyance direction by the conveyance guide member 16 disposed in the branching section of the sheet conveyance path 11 and is left as it is (or after being sent to the reverse conveyance path 17 and printed on both sides). The paper is discharged to the paper discharge unit 15 through the discharge roller pair 14.

  FIG. 3 is a block diagram illustrating an example of a control path used in the image forming apparatus 100. It should be noted that since various control of each part of the apparatus is performed when the image forming apparatus 100 is used, the control path of the entire image forming apparatus 100 becomes complicated. Therefore, here, a portion of the control path that is necessary for the implementation of the present invention will be mainly described.

  The control unit 90 includes a central processing unit (CPU) 91 as a central processing unit, a read only memory (ROM) 92 that is a read-only storage unit, a random access memory (RAM) 93 that is a read / write storage unit, A plurality of (here, two) I / Os that temporarily transmit control signals to and receive input signals from the operation unit 70. F (interface) 96 is provided at least. Further, the control unit 90 can be arranged at an arbitrary location inside the apparatus main body.

  The ROM 92 stores a control program for the image forming apparatus 100, data necessary for control, and the like that are not changed during use of the image forming apparatus 100. The RAM 93 stores necessary data generated during the control of the image forming apparatus 100, data temporarily required for controlling the image forming apparatus 100, and the like. Further, in the ROM 92 (or RAM 93), as will be described later, the scraping amount (scraping rate) per printed sheet used when calculating the layer thickness of the photosensitive layer 1b of the photosensitive drum 1 is the size and type of the paper 18. Stored every time. The counter 95 divides the number of prints into single print and continuous print and counts them up.

  In addition, the control unit 90 transmits a control signal from the CPU 91 to the respective units and apparatuses in the image forming apparatus 100 through the I / F 95. In addition, a signal indicating the state and an input signal are transmitted from each part or device to the CPU 91 through the I / F 95. Examples of each part and device controlled by the control unit 90 include the charging device 2 of the image forming unit P, the transfer roller 5, the voltage control circuit 41, the paper roughness detection sensor 50, and the operation unit 70.

  The image input unit 40 is a receiving unit that receives image data transmitted from the personal computer or the like to the image forming apparatus 100. The image signal input from the image input unit 40 is converted into a digital signal and then sent to the temporary storage unit 94.

  The voltage control circuit 41 is connected to the charging voltage power source 42, the developing voltage power source 43, and the transfer voltage power source 44, and operates each of these power sources according to an output signal from the control unit 90. By the control signal from the control circuit 41, the charging voltage power source 42 is supplied to the corona wire and grid in the charging device 2, the developing voltage power source 43 is supplied to the developing roller 4a in the developing device 4, the transfer voltage power supply 44 is supplied to the transfer roller 5, A predetermined voltage is applied to each.

  The paper roughness detection sensor 50 detects the surface roughness of the paper 18 conveyed from the paper storage unit 10. The paper roughness detection sensor 50 includes, for example, a light emitting element such as a light emitting diode that emits light incident on the paper 18, and a photodiode or phototransistor that receives a diffuse reflection component of light reflected from the paper 18 with respect to the incident light. A light receiving element. The light receiving element receives the diffuse reflection component of the above-described reflected light through a filter that blocks visible light and transmits infrared light in order to specify the surface roughness of the paper 18.

  The amount of infrared light incident on the light receiving element changes according to the surface roughness of the paper 18, and the output of the light receiving element changes. Specifically, the diffuse reflection component increases as the surface of the paper 18 is rough, and the diffuse reflection component decreases as the glossiness of the surface increases. The ROM 92 (or RAM 93) stores data indicating the correspondence between the output of the light receiving element and the surface roughness of the paper 18 in advance, and the surface roughness of the paper 18 is specified from the output of the light receiving element based on the data. To do. The paper roughness detection sensor 50 is disposed, for example, on the upstream side of the registration roller pair 13 in the image forming apparatus 100.

  The operation unit 70 is provided with a liquid crystal display unit 71 and LEDs 72 indicating various states. The user operates the stop / clear button of the operation unit 70 to stop image formation, and operates the reset button to operate the image. Various settings of the forming apparatus 100 are set to a default state. The liquid crystal display unit 71 displays the state of the image forming apparatus 100, and displays the image forming status and the number of copies to be printed. Various settings of the image forming apparatus 100 are performed from a printer driver of a personal computer.

  Hereinafter, the life detection control of the photosensitive drum 1, which is a characteristic part of the present invention, will be described. In the image forming apparatus 100 of the present invention, the amount of abrasion of the photosensitive layer 1b of the photoreceptor drum 1 is predicted, and the life (replacement time) of the photoreceptor drum 1 is notified based on the estimated amount of abrasion.

  Next, a method for calculating the amount of abrasion of the photosensitive layer 1b of the photosensitive drum 1 in the image forming apparatus 100 according to the first embodiment of the present invention will be described. FIG. 4 is a graph showing the transition of the layer thickness of the photosensitive layer 1b in the rotational axis direction of the photosensitive drum 1 when a small-size (A5 size in this case) paper 18 is passed. 3 is a graph showing the transition of the layer thickness of the photosensitive layer 1b in a sheet passing area and a non-sheet passing area of the drum 1.

  In FIG. 4, the rotation when passing 5K (5,000) sheets, passing 25K (25,000) sheets, passing 43K (43,000) sheets, and passing 68K (68,000) sheets. The layer thickness of the photosensitive layer 1b in the axial direction is indicated by a solid line, a broken line, an alternate long and short dash line, and a dotted line, respectively. The A5 paper width, transfer roller width, and cleaning blade width are indicated by arrows in FIG. Further, in FIG. 5, the change in the layer thickness of the photosensitive layer 1b at the center in the rotation axis direction (left and right direction in FIG. 4) of the photosensitive drum 1 is shown in the data series of ● and the left and right ends. The transition of the layer thickness of the photosensitive layer 1b is shown by the data series of ▲ and ×, respectively.

  When a sheet whose width direction size is smaller than the dimension of the photosensitive drum 1 in the rotational axis direction passes through the photosensitive drum 1, only the center portion of the photosensitive drum 1 in the rotational axis direction (left-right direction in FIG. 4) is the center. A region (sheet passing region) R1 through which the sheet passes is formed, and a region (non-sheet passing region) R2 through which the sheet does not pass is generated at both ends (left, right). As shown in FIGS. 4 and 5, the amount of abrasion of the photosensitive layer 1b in the non-contact region R2 is significantly increased as the number of sheets passed is larger than the amount of abrasion of the photosensitive layer 1b in the contact region R1. .

  Here, the relationship between the abrasion amount of the photosensitive layer 1b and the voltage application pattern at the transfer nip N will be examined. Table 1 shows an application pattern of the transfer voltage or the transfer reverse voltage at the transfer nip portion N when the small-size paper 18 is passed.

  In the paper passing region R1 through which the paper 18 passes, there are a pattern A state and a pattern B state. Specifically, while the sheet 18 is passing through the transfer nip N, a transfer current (forward transfer constant current) that causes the toner to move from the photosensitive drum 1 to the sheet 18 (transfer roller 5) flows. Since a transfer voltage is applied, pattern A is formed. Further, when the paper 18 does not pass through the transfer nip N, the application of the transfer bias is stopped, and a reverse transfer constant voltage for preventing the toner from adhering to the transfer roller 5 is applied, so that the pattern B is obtained.

  In the non-sheet passing region R2 where the paper 18 does not pass, there are a pattern B state and a pattern C state. Specifically, while the sheet 18 passes through the transfer nip N, a transfer voltage is applied so that a forward transfer constant current flows. However, since the sheet 18 does not pass in the non-sheet passing region R2, the pattern C Become. Further, when the sheet 18 does not pass through the transfer nip N, the application of the transfer voltage is stopped, and a reverse transfer constant voltage that prevents the toner from adhering to the transfer roller 5 is applied.

  Since the time in the state of the pattern B is the same in the paper passing area R1 and the non-paper passing area R2, the difference in the scraping amount of the photosensitive layer 1b shown in FIGS. This is caused by the difference in the amount of shaving. Pattern C is a state in which a transfer voltage is applied without a sheet interposed between the photosensitive drum 1 and the transfer roller 5, and a transfer current flows directly from the transfer roller 5 to the photosensitive drum 1. That is, it is considered that when the small-size paper 18 is passed, the phenomenon that the transfer current directly flows into the photosensitive drum 1 promotes the shaving of the photosensitive layer 1b.

  Therefore, in the present embodiment, the scraping rate (the scraping amount of the photosensitive layer 1b per printed sheet) is obtained by experiment for each size of the paper 18 to be passed, and the accumulation of each paper size counted by the counter 95 is obtained. Based on the number of printed sheets and the scraping rate, the scraping amount of the photosensitive layer 1b in the non-sheet passing region R2 where the scraping amount of the photosensitive layer 1b is maximized in the rotation axis direction of the photosensitive drum 1 is calculated. Then, the life of the photosensitive drum 1 is notified based on the calculated scraping amount. The paper size is determined based on a paper size detection sensor (not shown) disposed in the paper storage unit 10 and paper size information input from a personal computer.

Specifically, the scraping rate per printed sheet of the photosensitive layer 1b when the paper 18 of the maximum size (the same size as the paper-passable area) is passed is α1, and the size smaller than the maximum size (paper-passable area) Is smaller than the maximum size and the cumulative print number of the size smaller than the maximum size is T1 and T2, respectively. The maximum scraping amount Smax of the photosensitive layer 1b is expressed by the following formula (1).
Smax = α1 × T1 + α2 × T2 (1)

  Then, when the maximum scraping amount Smax calculated by the equation (1) becomes equal to or greater than a predetermined threshold value, it is determined that the photosensitive drum 1 has reached the end of its life and is notified to the user. In addition, as the photosensitive layer 1b, an organic photosensitive layer (OPC) and an amorphous silicon photosensitive layer (a-Si) are known, but the notification of the life of the photosensitive drum 1 according to the amount of abrasion of the photosensitive layer 1b is used for wear. This is particularly effective in an organic photosensitive layer (OPC) which is easy to be processed and has a large change in film thickness.

  Next, a method for calculating the amount of abrasion of the photosensitive layer 1b of the photosensitive drum 1 in the image forming apparatus 100 according to the second embodiment of the present invention will be described. In the present embodiment, the amount of abrasion of the photosensitive layer 1b is calculated in consideration of the attribute (surface roughness) of the paper 18.

  Even if the size of the paper 18 is the same, the amount of abrasion of the photosensitive layer 1b differs between the case where the paper 18 is plain paper and the case of poor paper. Specifically, in the case of rough paper having a surface roughness larger than that of plain paper, a large amount of paper dust is generated, so that the photosensitive layer 1b is damaged and the photosensitive layer 1b is easily scraped. Therefore, in the present embodiment, the scraping rate (the scraping amount of the photosensitive layer 1b per printed sheet) is obtained by experiments for each attribute of the paper 18 to be passed (whether it is plain paper or bad paper). The amount of abrasion of the photosensitive layer 1b is calculated based on the cumulative number of printed sheets and the abrasion rate of each sheet 18 (plain paper, bad paper) counted by the counter 95. Then, the life of the photosensitive drum 1 is notified based on the calculated scraping amount.

Specifically, the scraping rate per printed sheet of the photosensitive layer 1b when the plain paper and the rough paper having the maximum size (the same size as the passable area) are passed as the paper 18 is β1, β2, and the maximum size, respectively. Assuming that the cumulative number of printed sheets of plain paper and bad paper is T3 and T4, respectively, the maximum scraping amount Smax of the photosensitive layer 1b is expressed by the following equation (2).
Smax = β1 × T3 + β2 × T4 (2)

  When the maximum scrap amount Smax calculated by the equation (2) becomes equal to or greater than a predetermined threshold value, it is determined that the photosensitive drum 1 has reached the end of its life, and the user is notified.

  Next, a method for calculating the amount of abrasion of the photosensitive layer 1b of the photosensitive drum 1 in the image forming apparatus 100 according to the third embodiment of the present invention will be described. In the present embodiment, the amount of shaving of the photosensitive layer 1b is calculated in consideration of the total number of prints within a predetermined period (for example, one day) and the print pattern (single print or continuous print).

  In order to accurately recognize the life of the photosensitive drum 1, it is necessary to accurately calculate the amount of abrasion of the photosensitive layer 1b. In the first and second embodiments, the amount of abrasion of the photosensitive layer 1b is calculated according to the cumulative number of printed sheets. However, even if the number of accumulated printed sheets is the same, the amount of abrasion of the photosensitive layer 1b depends on the usage state of the photosensitive drum 1. Changes.

  For example, since the rotational speed of the photosensitive drum 1 is different between single-shot printing and continuous printing, the life of the photosensitive drum 1 is different even with the same cumulative number of printed sheets. If the amount is smaller, the temperature inside the apparatus is less likely to increase, and the photosensitive layer 1b is less likely to be scraped off.

  Therefore, in this embodiment, a scraping rate (abrasion amount of the photosensitive layer 1b per printed sheet) is obtained by experiment for each print pattern (single print or continuous print) and counted by the counter 95. The amount of abrasion of the photosensitive layer 1b is calculated on the basis of the cumulative number of printed sheets and the abrasion rate for each printing pattern.

Specifically, the scraping rate per printed sheet of the photosensitive layer 1b in single-shot printing and continuous printing when the maximum size plain paper is passed as the paper 18 is γ1, γ2, cumulative in single-shot printing and continuous printing, respectively. Assuming that the number of printed sheets is T5 and T6, respectively, the maximum scraping amount Smax of the photosensitive layer 1b is expressed by the following equation (3).
Smax = γ1 × T5 + γ2 × T6 (3)

Furthermore, since the temperature inside the apparatus is likely to increase as the total number of printed sheets per day increases, the photosensitive layer 1b is easily scraped. Therefore, the amount of abrasion is corrected by multiplying the amount of abrasion calculated by the equation (3) by a correction coefficient corresponding to the total number of printed pages per day. Specifically, assuming that the correction coefficient corresponding to the total number of printed pages per day is k, the maximum scraping amount Smax of the photosensitive layer 1b is expressed by the following equation (4).
Smax = (γ1 × T5 + γ2 × T6) × k (4)

  The correction coefficient k may be increased as the total number of printed pages per day increases. For example, if the correction coefficient when the total number of prints per day is less than 1000 is k1, the correction coefficient when it is 1000 to 2000 sheets is k2, and the correction coefficient when it is 2000 or more is k3, k1 <K2 <k3.

  FIG. 6 is a flowchart illustrating a notification control example of the replacement timing of the photosensitive drum 1 based on the maximum scraping amount Smax of the photosensitive layer 1b calculated in the image forming apparatus 100 of the first embodiment. With reference to FIGS. 1 to 5, the notification procedure of the replacement timing of the photosensitive drum 1 will be described along the steps of FIG.

  When a printing command is input from a personal computer or the like and printing is started (step S1), the counter 95 determines the number of printed sheets for each size of paper 18 (the maximum size and a size smaller than the maximum size) at the start of use of the photosensitive drum 1. The accumulated number of printed sheets T1 and T2 is counted (step S2).

  Next, the control unit 90 determines whether or not printing has been completed (step S3). If printing is continuing (No in step S3), the process returns to step S2 to continue counting the cumulative number of printed sheets T1 and T2. If the printing is completed (Yes in step S3), the photosensitive layer 1b is obtained from the equation (1) based on the cumulative number of printed sheets T1 and T2 and the scraping rates α1 and α2 for each paper size read from the RAM 93. Is calculated (step S4).

  Then, it is determined whether or not the calculated maximum scrap amount Smax is equal to or greater than a predetermined threshold value S1 (step S5). When Smax ≧ S1 (Yes in step S5), the time for replacing the photosensitive drum 1 is notified (step S6). Specifically, a message prompting replacement of the photosensitive drum 1 such as “Please replace the photosensitive drum” is displayed on the liquid crystal display unit 71. On the other hand, if Smax <S1 in step S5 (No in step S5), the process returns to step S1, and the process of steps S1 to S6 is repeated when the next print command is input.

  According to the above control, the maximum scraping amount Smax of the photosensitive layer 1b is calculated from the scraping rates α1 and α2 of the photosensitive layer 1b for each paper size and the cumulative number of prints T1 and T2 for each paper size. The maximum scraping amount Smax of the photosensitive layer 1b can be accurately calculated regardless of the ratio of the paper 18 having a size smaller than the maximum size, and the photosensitive drum 1 is based on the calculated maximum scraping amount Smax. Can properly notify the life of Therefore, the photosensitive drum 1 can be replaced at an appropriate time when high-quality image quality can be maintained.

  In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the control shown in FIG. 6, the maximum scraping amount Smax is calculated when the continuous printing is completed and the life of the photosensitive drum 1 is notified. However, the control in FIG. The maximum scraping amount Smax is calculated every time the sheet 18 is passed, and when the maximum scraping amount Smax is equal to or greater than the threshold value, the life of the photosensitive drum 1 is notified even during continuous printing. good.

Further, by combining the method for calculating the amount of abrasion of the photosensitive layer 1b described in the above embodiments, the amount of abrasion of the photosensitive layer 1b can be predicted more accurately. For example, when the first embodiment and the second embodiment are combined, the scraping rates per printed sheet of the photosensitive layer 1b when the maximum size plain paper and the rough paper are passed are β1, β2, and the maximum size respectively. The cumulative number of printed sheets of plain paper and bad paper is T3, T4, respectively. When the plain paper and bad paper other than the maximum size are passed, the scraping rate per printed sheet of the photosensitive layer 1b is other than β3, β4, and the maximum size, respectively. Assuming that the cumulative number of printed sheets of plain paper and rough paper is T7 and T8, respectively, the maximum scraping amount Smax of the photosensitive layer 1b is expressed by the following equation (5).
Smax = (β1 × T3 + β2 × T4) + (β3 × T7 + β4 × T8) (5)

  Similarly, the first embodiment and the third embodiment, the second embodiment and the third embodiment can be combined, or the first, second and third embodiments can be combined.

  Further, the present invention is not limited to the monochrome printer as shown in FIG. 1, but can be applied to various image forming apparatuses such as monochrome and color copiers, digital multifunction peripherals, color printers, and facsimiles.

  The present invention can be used in an image forming apparatus including an exchangeable image carrier. By utilizing the present invention, it is possible to provide an image forming apparatus capable of accurately predicting the abrasion amount of the photosensitive layer formed on the image carrier regardless of the state of use of the apparatus and accurately reporting the life of the image carrier. it can.

P Image forming section 1 Photosensitive drum (image carrier)
DESCRIPTION OF SYMBOLS 1a Support body 1b Photosensitive layer 2 Charging apparatus 4 Developing apparatus 5 Transfer roller (transfer member)
18 paper (recording medium)
50 Paper roughness detection sensor (surface condition detection device)
71 Liquid crystal display (notification device)
90 control unit 100 image forming apparatus

Claims (7)

An image carrier having a photosensitive layer formed on the surface;
A transfer member disposed in contact with the image carrier and transferring a toner image formed on the image carrier to a recording medium;
A controller that determines the replacement time of the image carrier based on the amount of abrasion of the photosensitive layer;
A notification device for notifying the replacement time of the image carrier determined by the control unit;
In an image forming apparatus comprising:
The control unit predicts the amount of abrasion of the photosensitive layer according to at least one of the size or surface state of the recording medium, and uses the notification device when the estimated amount of abrasion exceeds a predetermined threshold. An image forming apparatus that performs notification for prompting replacement of an image carrier. The control unit determines that the image carrier is in a replacement period when a maximum amount of scraping Smax of the photosensitive layer calculated based on the following formula (1) becomes a predetermined value or more. The image forming apparatus according to claim 1.
Smax = α1 × T1 + α2 × T2 (1)
However,
α1: Abrasion amount of the photosensitive layer per sheet of printing on the maximum size recording medium α2: Abrasion amount of the photosensitive layer per sheet of printing on a recording medium other than the maximum size T1: The above-described recording medium of the maximum size recording medium Cumulative number of printed sheets T2 from the start of use of the image carrier: The cumulative number of printed sheets from the start of use of the image carrier of a recording medium other than the maximum size. A surface state detection device for detecting the surface state of the recording medium,
The control unit detects whether the recording medium is plain paper or rough paper having a surface roughness larger than that of the plain paper using the surface state detection device, and is based on the following formula (2): 2. The image forming apparatus according to claim 1, wherein when the calculated maximum amount of scraping Smax of the photosensitive layer becomes equal to or greater than a predetermined value, it is determined that the image carrier is in a replacement period.
Smax = β1 × T3 + β2 × T4 (2)
However,
β1: Abrasion amount of the photosensitive layer per printed sheet when the recording medium is plain paper β2: Abrasive amount of the photosensitive layer per printed sheet when the recording medium is rough paper T3: The image carrier The cumulative number of printed plain paper sheets T4 from the start of use of the image carrier: the cumulative number of printed sheets of poor paper from the start of use of the image carrier. An image carrier having a photosensitive layer formed on the surface;
A transfer member disposed so as to be in contact with the image carrier, forming a transfer nip portion, and transferring a toner image formed on the image carrier to a recording medium passing through the transfer nip portion;
A controller that determines the replacement time of the image carrier based on the amount of abrasion of the photosensitive layer;
A notification device for notifying the replacement time determined by the control unit;
In an image forming apparatus comprising:
The control unit predicts the amount of abrasion of the photosensitive layer according to whether the printing operation is single-shot printing or continuous printing, and uses the notification device when the predicted amount of abrasion exceeds a predetermined threshold. An image forming apparatus that performs notification for prompting replacement of the image carrier. The control unit determines that the image carrier is in a replacement period when a maximum amount of scraping Smax of the photosensitive layer calculated based on the following formula (3) becomes a predetermined value or more. The image forming apparatus according to claim 4.
Smax = γ1 × T5 + γ2 × T6 (3)
However,
γ1: Abrasion amount of the photosensitive layer per sheet when single printing is performed γ2: Abrasion amount of the photosensitive layer per sheet when continuous printing is performed T5: The above-described amount when the single printing is performed Cumulative number of printed sheets T6 from the start of use of the image carrier: The cumulative number of printed sheets from the start of use of the image carrier when continuous printing is performed.   The control unit calculates a maximum amount of scraping Smax by multiplying the amount of shaving of the photosensitive layer calculated based on the equation (3) by a correction coefficient corresponding to the total number of printed sheets per day. Item 6. The image forming apparatus according to Item 5.   7. The image forming apparatus according to claim 1, wherein an organic photosensitive layer is formed as the photosensitive layer on the image carrier.