JP7838005B2 - Image forming apparatus - Google Patents

Description

This invention relates to an image forming apparatus that forms images using an electrophotographic method.

Conventionally, image forming apparatuses that form images on recording media such as recording paper utilize a latent image unit, which includes a photosensitive drum (image carrier), a charging device, and a cleaning device, to form an electrostatic latent image. Furthermore, a developing unit, which includes a toner (developer agent) and a developer carrier, then visualizes this electrostatic latent image to form the final image. Generally, the lifespan of the latent image unit and the developing unit differs. Specifically, the lifespan of the latent image unit is determined by the wear and tear of the image carrier and cleaning device, while the lifespan of the developing unit is determined by the remaining toner and the degree of toner degradation due to repeated use. Each lifespan varies depending on the user's usage. Therefore, image forming apparatuses that separate the latent image unit and the developing unit into process cartridges have been proposed (see Patent Document 1). This allows for efficient use of both the latent image unit and the developing unit until the end of their respective lifespans.

Japanese Patent Publication No. 2004-279689

Incidentally, even when the development unit's operation history reaches the threshold for prompt replacement and the user is notified, the user may continue to use the development unit. This is because the reason for prompt replacement of the development unit is the deterioration of the toner inside the development unit due to repeated friction. Although the development unit is being prompted to replace due to toner deterioration, if there is still toner remaining, the user may continue to use the development unit even after the replacement notification.

However, if the developing unit continues to be used even after the recommended replacement has been made, there is a risk of damage to the cleaning device. If this damage occurs, problems such as the appearance of vertical streaks in the image may occur.

Therefore, even if the user continues to use the developing unit after being prompted to replace it, it is desirable to further reduce problems related to the cleaning device.

To achieve the above objective, an image forming apparatus is provided in which a latent image unit and a developing unit can be attached to and detached from the main body of the apparatus, wherein the latent image unit comprises a rotatable image carrier on which an electrostatic latent image is formed, and a cleaning member that contacts the image carrier to remove developer from the surface of the image carrier, the developing unit comprises a developer carrier that develops the electrostatic latent image formed on the image carrier with developer , and further comprises a control unit and a notification device that provides notification regarding the promotion of replacement of the developing unit, wherein the control unit acquires first information according to the amount of use of the developing unit after notification regarding the promotion of replacement by the notification device, and the acquired first Based on the information, the control unit causes the notification device to issue a warning regarding the protection of the latent image unit; the control unit acquires second information corresponding to the amount of use of the latent image unit, and based on the first and second information, causes the notification device to issue a warning regarding the protection of the latent image unit; the control unit advances the timing of issuing the warning regarding the protection of the latent image unit to the notification device the greater the amount of use of the developing unit, even if the amount of use of the developing unit is the same; and the control unit advances the timing of issuing the warning regarding the protection of the latent image unit to the notification device the greater the amount of use of the latent image unit, even if the amount of use of the developing unit is the same.

Alternatively, the present invention is an image forming apparatus in which a latent image unit and a developing unit can be attached to and detached from the apparatus body, wherein the latent image unit has a rotatable image carrier on which an electrostatic latent image is formed, and a cleaning member that contacts the image carrier to remove developer from the surface of the image carrier, the developing unit has a developer carrier that develops the electrostatic latent image formed on the image carrier with a developer image, and further, the image forming apparatus has a charging means, a control unit, a notification device that provides notification regarding the promotion of replacement of the developing unit, and the control unit according to the amount of use of the developing unit The system acquires first information, and based on the acquired first information, causes the notification device to issue a notification regarding the promotion of replacement of the developing unit. After the notification regarding the promotion of replacement is issued, the control unit estimates, for the same combination of the developing unit and the latent image unit, that the amount of film thickness removal on the image carrier surface relative to a predetermined amount of use of the latent image unit is greater than the amount of film thickness removal on the image carrier surface relative to the predetermined amount of use before the notification regarding the promotion of replacement is issued. The control unit then controls the charging bias to the charging means according to the film thickness on the image carrier surface.

According to the present invention, even if the user continues to use the developing unit after being prompted to replace it, problems related to the cleaning device can be further reduced.

Diagram illustrating an image forming apparatus. Cross-sectional view of the drum cartridge along its longitudinal direction (direction of the rotation axis). Cross-sectional view of the developing cartridge along its longitudinal direction (direction of the rotation axis). Control block diagram of an image forming apparatus Flowchart for issuing a drum cartridge protection warning Enlarged view of the cleaning blade edge. Flowchart for correcting the amount of film thickness reduction on the photosensitive drum Graph of toner overlay for Vback Graph showing the potential and fouling characteristics of the drum surface film thickness.

The embodiments for carrying out this invention will be described in detail below with reference to the drawings, based on examples. However, the dimensions, materials, shapes, and relative arrangements of the components described in these embodiments should be appropriately modified depending on the configuration and various conditions of the device to which the invention is applied. In other words, the scope of this invention is not intended to be limited to the following embodiments.

In this embodiment, if the developing unit continues to be used after exceeding the threshold for prompting its replacement, the user is notified of a latent image unit protection warning. This prevents image defects such as vertical streaks caused by damage to the cleaning device. Furthermore, by issuing the latent image unit protection warning earlier as the latent image unit's usage progresses, the warning can be issued more reliably to mitigate damage.

First, let's explain the background. Figure 6 is an enlarged view of the cleaning blade edge, illustrating the mechanism by which edge chipping occurs on the cleaning blade 6. The cleaning blade 6 is a blade member that extends in the counter direction relative to the rotation direction R of the photosensitive drum 1. The cleaning blade 6 contacts the photosensitive drum 1 and cleans the drum by scraping off residual toner transfer on the drum 1.

As shown in Figure 6, the cleaning blade 6 contacts the photosensitive drum 1 in a counter-direction relative to its rotational direction R. That is, the edge portion E, which extends in the opposite direction to the direction of movement of the photosensitive drum 1 relative to the cleaning blade 6, contacts the surface of the photosensitive drum 1. Therefore, as the photosensitive drum 1 rotates, the edge portion E of the cleaning blade 6 becomes trapped in the direction of movement of the photosensitive drum 1. The toner additive that has migrated to the photosensitive drum 1 accumulates in this trapped wedge portion (contact area), forming a layer (hereinafter referred to as the blocking layer 14). In other words, the toner additive is supplied to the contact area between the cleaning blade 6 and the photosensitive drum 1, and the blocking layer 14 is formed at the contact area between the cleaning blade 6 and the photosensitive drum 1. A portion of the toner additive contained in this blocking layer 14 interposes between the photosensitive drum 1 and the cleaning blade 6, preventing an increase in frictional resistance between the photosensitive drum 1 and the cleaning blade 6.

However, if you continue to use a developer cartridge 200 that has reached the end of its lifespan, the frictional resistance between the photosensitive drum 1 and the cleaning blade 6 will increase, and a portion of the cleaning blade edge may chip or break (edge chipping). In the case of a developer unit that has reached the end of its lifespan in terms of toner degradation, the toner in the developing unit is almost completely depleted due to repeated friction, with the toner additives migrating to the photosensitive drum or becoming embedded within the toner. Therefore, the blocking layer becomes depleted, and the frictional resistance between the photosensitive drum and the cleaning blade increases.

Furthermore, we will explain why the usage of the drum cartridge 210 is related to edge chipping of the cleaning blade 6. As the usage of the drum cartridge 210 increases, the edge of the cleaning blade 6 accumulates stress due to the rotation of the photosensitive drum 1 and the stopping and starting operations of the photosensitive drum 1. As the stress on the edge of the cleaning blade 6 accumulates, it eventually causes the rubber at the edge to break, resulting in edge chipping. Therefore, the more the drum cartridge 210 is used, the more likely edge chipping of the cleaning blade 6 is to occur. In other words, continuing to use the developing unit after being advised to replace it during the latter half of the latent image unit's lifespan will increase the likelihood of damage to the cleaning device.

[Image forming apparatus]
First, the overall configuration of the image forming apparatus will be explained with reference to Figure 1. The image forming apparatus includes copiers, printers, facsimile machines, word processors, and multifunction printers using electrophotographic image forming or electrostatic recording methods. The image forming apparatus 100 is, for example, an A4 full-color laser beam printer employing an in-line method or an intermediate transfer method, and can form a full-color image on a recording material (for example, recording paper, plastic sheet, cloth, etc.) according to image information. Image information is input to the main body of the image forming apparatus 100 from an image reading device connected to the main body of the image forming apparatus 100, or from a host device such as a personal computer that is communicatively connected to the main body of the image forming apparatus 100. The image forming apparatus 100 has image forming units SY, SM, SC, and SK for forming images of yellow (Y), magenta (M), cyan (C), and black (K). In Embodiment 1, the image forming units SY, SM, SC, and SK are arranged in a line in a direction intersecting the vertical direction. The image-forming units SY, SM, SC, and SK consist of drum cartridges 210 (210Y, 210M, 210C, 210K) as latent image units and developing cartridges 200 (200Y, 200M, 200C, 200K) as developing units. Each of the developing cartridges 200 and drum cartridges 210 can be attached to and detached from the main body of the image forming apparatus 100 via mounting means such as mounting guides and positioning members provided on the main body of the image forming apparatus 100. In Embodiment 1, all drum cartridges 210 for each color have the same shape, and all developing cartridges 200 for each color have the same shape. Each developing cartridge 200 contains toner for yellow (Y), magenta (M), cyan (C), and black (K), respectively.

The photosensitive drum 1 is a rotatable image carrier that is rotated by a driving means (drive source). A scanner unit (exposure device) 30 is arranged around the photosensitive drum 1. The scanner unit 30 is an exposure means that irradiates a laser based on image information to form an electrostatic image (electrostatic latent image) on the photosensitive drum 1. Laser exposure is initiated in the main scanning direction (direction perpendicular to the transport direction of the recording material 12) from a position signal in the polygon scanner called BD (Beam Detect) for each scanning line. On the other hand, in the sub-scanning direction (transport direction of the recording material 12), laser exposure is initiated with a predetermined time delay from the TOP (top of paper) signal, which originates from a switch (not shown) in the transport path of the recording material 12. This allows the four image formation units SY, SM, SC, and SK to always perform laser exposure on the same position on the photosensitive drum 1. An intermediate transfer belt 31 is positioned opposite the four photosensitive drums 1, serving as an intermediate transfer body for transferring the toner image (developer image) from the photosensitive drums 1 to the recording material 12. The intermediate transfer belt 31, formed as an endless belt, contacts all the photosensitive drums 1 and circulates (rotates) in the direction of arrow B (counterclockwise) as shown in Figure 1. The intermediate transfer belt 31 is supported by multiple support members: a drive roller 31a and a driven roller 31b. On the inner circumferential surface of the intermediate transfer belt 31, four primary transfer rollers 32 are arranged in parallel, facing each photosensitive drum 1, serving as primary transfer means. A bias opposite to the normal charging polarity of the toner is applied to the primary transfer rollers 32 from a primary transfer bias power supply (high-voltage power supply), which is a primary transfer bias application means (not shown). This transfers (primary transfer) the toner image from the photosensitive drums 1 onto the intermediate transfer belt 31.

Furthermore, a secondary transfer roller 33, which serves as a secondary transfer means, is positioned on the outer circumferential surface of the intermediate transfer belt 31. A bias opposite to the normal charging polarity of the toner is applied to the secondary transfer roller 33 from a secondary transfer bias power supply (high voltage power supply), which serves as a secondary transfer bias application means (not shown). As a result, the toner image on the intermediate transfer belt 31 is transferred (secondary transfer) to the recording material 12. For example, when forming a full-color image, the above process is performed sequentially in the image-making units SY, SM, SC, and SK, and the toner images of each color are sequentially superimposed on the intermediate transfer belt 31 for primary transfer. After that, the recording material 12 is transported to the secondary transfer unit in synchronization with the movement of the intermediate transfer belt 31. Then, through the action of the secondary transfer roller 33, which is in contact with the intermediate transfer belt 31 via the recording material 12, the four-color toner images on the intermediate transfer belt 31 are secondary transferred to the recording material 12 all at once. The recording material 12 on which the toner images have been transferred is transported to a fixing device 34, which serves as a fixing means. In the fixing device 34, heat and pressure are applied to the recording material 12, thereby fixing the toner image to the recording material 12. The image forming apparatus 100 also includes a control unit 101. The control unit 101 controls the entire image forming apparatus 100 and acquires various information from the host device via the input/output interface 114.

[Drum Cartridge]
Next, the configuration of the drum cartridge 210 will be described. Figure 2 is a cross-sectional (main cross-sectional) view of the drum cartridge 210 along the longitudinal direction (rotation axis direction) of the photosensitive drum 1. The photosensitive drum 1 is rotatably mounted to the drum cartridge 210 via bearings (not shown). The photosensitive drum 1 is driven to rotate in the direction of arrow A shown in Figure 2 in accordance with the image forming operation by receiving the driving force of the drive motor M210, which serves as the driving means. In Embodiment 1, the drum cartridge 210 has a diameter of Φ24 mm and rotates at 200 mm/second. The drum cartridge 210 also has a charging roller 2 and a cleaning blade 6 made of an elastic material that acts as a cleaning member (contact member) that contacts the surface of the rotating photosensitive drum 1. The charging roller 2 is subjected to a bias sufficient to place any desired charge on the photosensitive drum 1 from a charging bias power supply (high voltage power supply), which serves as a charging bias application means (not shown). In Embodiment 1, the bias is set so that the potential on the photosensitive drum 1 (charging potential: Vd) is -500V. Based on the image information, a laser beam 35 is emitted from the scanner unit 30 to form an electrostatic image (electrostatic latent image) on the photosensitive drum 1.

The cleaning blade 6 consists of a rubber blade 6a supported by a cleaning support plate 6b, with the rubber blade 6a and the cleaning support plate 6b being integrally formed. For example, the rubber blade 6a is made of urethane rubber with a thickness of 2 mm and an MD-1 hardness of 60-80° at 23°C. The cleaning blade 6 is fixed to the drum cartridge frame 11, and the tip of the rubber blade 6a is positioned to contact the photosensitive drum 1. The cleaning blade 6 uses the free end of the rubber blade 6a to scrape off toner that has not been transferred to the intermediate transfer belt 31 and remains on the surface of the photosensitive drum 1, thereby removing toner from the surface of the photosensitive drum 1. Furthermore, the drum cartridge 210 is provided with a non-volatile memory (hereinafter referred to as "O-memory") m1 as a first memory. The O-memory m1 stores information corresponding to the usage amount of the drum cartridge 210.

The information corresponding to the usage of drum cartridge 210 is information related to the operation of the photosensitive drum 1, such as the cumulative number of rotations and cumulative rotation time. This information may also be a value obtained by dividing the information related to the operation of the photosensitive drum 1 by a predetermined lifespan value for the photosensitive drum 1. Alternatively, it may be a percentage value obtained by multiplying that value by 100. The predetermined value for the photosensitive drum 1 is, for example, the rotation speed or rotation time of the photosensitive drum 1, and is a value set based on the lifespan of the photosensitive drum 1 (the value corresponding to the usage of drum cartridge 210 when the replacement reminder message is displayed). Furthermore, the information corresponding to the usage of drum cartridge 210 may also be a value obtained by subtracting the cumulative number of rotations or cumulative rotation time of the photosensitive drum 1 from the predetermined value for the photosensitive drum 1. Additionally, information related to the operation of the photosensitive drum 1, such as the cumulative number of rotations or cumulative rotation time, can be substituted with other parameters that have a certain degree of correlation, such as the number of printed pages or toner usage.

The control unit 101 can then obtain the usage amount of the drum cartridge 210, such as how much it has been used and how much it has operated, based on the information stored in the O memory m1. In other words, information corresponding to the usage amount of the drum cartridge 210, corrected by the control unit 101 based on information related to the operation amount of the photosensitive drum 1, such as the cumulative rotation time and cumulative rotation count, or equivalent information, is written to the O memory m1 by the control unit 101.

[Developing Cartridge]
Next, the configuration of the developing cartridge 200, which is installed in the image forming apparatus, will be described. Figure 3 is a cross-sectional (main cross-sectional) view of the developing cartridge 200 as seen along the longitudinal direction (rotation axis direction) of the developing roller 4. The developing cartridge 200 consists of a developing chamber 20a and a developer storage chamber 20b, with the developer storage chamber 20b located vertically below the developing chamber 20a. Toner 9, which is used as a developer, is stored inside this developer storage chamber 20b. Silica particles with a particle size of 20 nm are added to the surface of the toner 9 as an external toner additive (external additive particles). The normal charge polarity of this toner 9 is negative, and the following description will focus on the case where a negatively charged toner is used as the toner 9. However, the toner 9 is not limited to a negatively charged toner. Furthermore, the developer storage chamber 20b is provided with a developer transport member 21 for transporting the toner 9 to the developing chamber 20a, and the toner 9 is transported to the developing chamber 20a by the developer transport member 21 rotating in the direction of arrow G shown in Figure 3.

The developing chamber 20a is provided with a developing roller 4, which acts as a developer carrier and rotates in the direction of arrow D shown in Figure 3 by receiving the driving force of a drive motor M200, which acts as a developing drive means, and contacting the photosensitive drum 1. In Embodiment 1, the developing roller 4 and the photosensitive drum 1 rotate so that their surfaces move in the same direction at their opposing parts (contact parts), and the developing roller 4 rotates 150% faster than the photosensitive drum 1. The developing roller 4 is subjected to a bias from a developing bias power supply (high voltage power supply), which acts as a developing bias application means (not shown), which is sufficient to develop the electrostatic latent image on the photosensitive drum 1 as a toner image and make it visible. Inside the developing chamber 20a, a toner supply roller (hereinafter simply referred to as "supply roller") 5 is arranged to supply toner 9 transported from the developer storage chamber 20b to the developing roller 4. Also inside the developing chamber 20a, a toner amount regulating member 8 is arranged to regulate the amount of toner 9 coated on the developing roller 4 supplied by the supply roller 5 and to apply charge. The developing cartridge 200 is equipped with a second non-volatile memory (hereinafter referred to as "DT memory") m2. The DT memory m2 stores information corresponding to the amount of developing cartridge 200 used.

The information corresponding to the usage of the developing cartridge 200 includes, for example, information related to the operation of the developing cartridge, such as the cumulative number of rotations or cumulative time of the developing roller 4.

Furthermore, even with the same amount of drive on the developing roller, the information corresponding to the amount of developing cartridge 200 used differs depending on (1) the operating mode of the image forming apparatus, (2) the cumulative toner usage/remaining toner, (3) the operating environment, and (4) the page print rate when the developing roller 4 rotates. In other words, the CPU 111 corrects the amount of drive on the developing roller 4 (cumulative rotations, cumulative time) based on this information (1) to (4), and obtains information corresponding to the amount of developing cartridge 200 used. This obtained information corresponding to the amount of developing cartridge 200 used can essentially be considered as the degree of deterioration of the toner stored in the developing cartridge 200.

Here, when the developing roller 4 rotates, the operating modes of the image forming apparatus include (1) the pre-rotation operation, which is a preparatory operation before image formation; the image shaping operation, which forms an image on the recording medium; and the post-rotation operation, which is a preparatory operation after image formation.

Furthermore, when the CPU 111 weights the amount of operation of the developing cartridge, it uses the cumulative toner usage/remaining toner amount from (2). For example, for a single developing cartridge 200, if the cumulative toner usage is high or the remaining toner is low, the CPU overestimates the amount of operation of the developing cartridge. Alternatively, the CPU 111 may overestimate the information corresponding to the usage of the developing cartridge 200, rather than the amount of operation of the developing cartridge itself, by correcting the information corresponding to the usage of the developing cartridge 200. It may also correct both the amount of operation of the developing cartridge and the information corresponding to the usage of the developing cartridge 200.

Furthermore, regarding (3) and (4), the CPU 11 corrects the information corresponding to the amount of operation of the developing cartridge and/or the amount of usage of the developing cartridge 200, according to the operating environment of the image forming apparatus and the page print rate. For example, in low-temperature, low-humidity environments such as 15°C and 10% humidity, or high-temperature, high-humidity environments such as 30°C and 80% humidity, the amount of operation of the developing cartridge is estimated to be larger than in the standard environment (e.g., 23°C and 50% humidity). Also, as the page print rate decreases, the amount of toner used is increased, and the amount of usage of the developing cartridge is estimated to be larger. In this case, the print rate is estimated on a page-by-page basis.

In this way, the CPU 111, by requesting information corresponding to the amount of toner used in the developing cartridge 200 according to various circumstances, can, in some cases, appropriately display a message prompting replacement even if there is still toner remaining in the developing cartridge 200.

Furthermore, toner usage is the amount of toner 9 used out of the toner 9 contained in the developer cartridge 200. Toner remaining is the amount of toner 9 remaining out of the toner 9 contained in the developer cartridge 200. Toner usage may also be determined by subtracting the toner remaining from the amount of toner in the developer cartridge 200 before use. Alternatively, the toner remaining may be determined by subtracting the toner usage from the amount of toner in the developer cartridge 200 before use.

Here, the information corresponding to the amount of development cartridge 200 used may be the value corrected by the CPU 111 itself, or it may be the value obtained by dividing that value by a predetermined lifespan value. It may also be a percentage value obtained by multiplying that value by 100. The predetermined value for the development roller 4 is, for example, the rotation speed or rotation time of the development roller 4, and is a value set based on the lifespan of the development roller 4 (a value corresponding to the amount of development cartridge 200 used when the replacement reminder message is displayed). The information corresponding to the amount of development cartridge 200 used may be the amount of toner used divided by the amount of toner in the development cartridge 200 when new. It may also be a percentage value obtained by multiplying that value by 100. Furthermore, the information corresponding to the amount of development cartridge 200 used may be the amount of remaining toner divided by the amount of toner in the development cartridge 200 when new. It may also be a percentage value obtained by multiplying that value by 100. In this way, information related to the amount of operation of the development roller 4, such as the cumulative rotation speed and cumulative rotation time, can be replaced with any parameter that has a certain degree of correlation with it. In addition, it can also be replaced with, for example, the number of printed pages.

The control unit 101 can acquire information corresponding to the usage of the developing cartridge 200 based on the information stored in the DT memory m2. In other words, the information corresponding to the usage of the developing cartridge 200, obtained by correcting the drive amount of the developing roller 4 (cumulative rotations, cumulative time), is written to the DT memory m2 by the control unit 101.

[Block diagram]
Next, the control configuration of the image forming apparatus 100 will be described using Figure 4. Figure 4 is a control block diagram in Embodiment 1. The control unit 101 has a CPU (Central Processing Unit) 111, which is the central element for performing calculations, memory such as ROM 112 and RAM 113, which are storage means, and an input/output I/F 114 for input and output of information with peripheral devices. The CPU 111 is also called a processor. The CPU 111 is not limited to a single processor, but may be a multi-processor configuration. The CPU 111 performs various controls of the control unit 101 using ROM 112 and RAM 113. Sensor detection results, calculation results, etc. are stored in RAM 113, and ROM 112 is a rewritable non-volatile storage means that stores control programs, pre-determined data tables, various variables, etc.

The control unit 101 is a control means that comprehensively controls the operation of the image forming apparatus 100, and each control target in the image forming apparatus 100 is connected via the input/output interface 114.

The image forming unit 510 includes a motor drive unit 511, a high-voltage power supply 512, an exposure control unit 513, and a contact/separation unit 514, and controls the motor drive unit 511, the high-voltage power supply 512, the exposure control unit 513, and the contact/separation unit 514. Alternatively, the control unit 101 may control the motor drive unit 511, the high-voltage power supply 512, the exposure control unit 513, and the contact/separation unit 514.

The motor drive unit 511 includes various motors and is a power source for rotating the polygon scanner, photosensitive drum 1, and developing roller 4, etc. It operates based on control signals from the control unit 101 or the image forming unit 510.

The high-voltage power supply 512 is a power supply that applies high voltage to the photosensitive drum 1, charging roller 2, developing roller 4, primary transfer roller 32, secondary transfer roller 33, and fixing device 34, etc.

The exposure control unit 513 transmits a signal indicating the light intensity of the laser beam 35 irradiated onto the photosensitive drum 1 to the scanner unit 30.

The contact/separation section 514 switches between a contact position where the developing roller 4 is in contact with the photosensitive drum 1 and a separation position where the developing roller 4 is separated from the photosensitive drum 1. The contact/separation section 514 also switches between a contact position where the intermediate transfer belt 31 is in contact with the photosensitive drum 1 and a separation position where the intermediate transfer belt 31 is separated from the photosensitive drum 1.

The environmental sensor 102 is a temperature and humidity sensor provided in the image forming apparatus 100, and transmits temperature and humidity data to the control unit 101. Data communication between the control unit 101 and O memory m1 is performed via the drum memory communication unit 515, and data communication between the control unit 101 and DT memory m2 is performed via the development memory communication unit 516. O memory m1 and DT memory m2 are used by the control unit 101 when determining information according to the usage amount of the drum cartridge 210 and the development cartridge 200. Data stored in DT memory m2 is sent to the control unit 101 via the development memory communication unit 516. The control unit 101 notifies the user of a protection warning for the drum cartridge 210 based on the usage information of O memory m1 and DT memory m2. The notification to the user is made via a display/operation panel (a display device provided in the image forming apparatus 100, or a device with a display) which serves as a notification device. Furthermore, the control unit 101 controls the exchange of various electrical information signals, the timing of drives, and other functions, including flowchart processing, which will be described later.

[Process leading up to drum cartridge protection warning notification]
The process for displaying a message prompting replacement of the developing cartridge 200 in Example 1 is explained using the flowchart in Figure 5(a), and the process up to the notification of a protection warning for the drum cartridge 210 is explained using the flowchart in Figure 5(b). In the flowcharts in Figures 5(a) and 5(b), processing is performed for each of the image-forming units SY, SM, SC, and SK.

For example, when the usage information for the developing cartridge 200 exceeds the threshold for a replacement reminder, a replacement reminder message is displayed on the operation/display panel 51 (notification device). Upon receiving this notification, the user can then choose whether to continue the image formation process. The process leading up to the display of the replacement reminder message will be explained below using the flowchart in Figure 5(a).

After the image forming apparatus 100 is powered on, or after the cartridge replacement door is opened or closed, the image forming apparatus 100 becomes operational, and the flow shown in Figure 5(a) begins (S1).

The control unit 101 then communicates with the O memory m1 mounted on the drum cartridge 210 via the drum memory communication unit 515. The control unit 101 (CPU 111) then acquires information (second information) corresponding to the usage amount of the drum cartridge 210 from the respective O memory m1 of the image units SY, SM, SC, and SK (S2). The information corresponding to the usage amount of the drum cartridge 210 is as described above.

Furthermore, the control unit 101 communicates with the DT memory m2 installed in the developing cartridge 200 via the developing memory communication unit 516, and obtains information (first information) corresponding to the amount of developing cartridge 200 used from the respective DT memory m2 of the image-making units SY, SM, SC, and SK (S3). The information corresponding to the amount of developing cartridge 200 used is as described above.

The control unit 101 then determines whether the acquired usage information for each color drum cartridge 210 and each color developer cartridge 200 exceeds the replacement threshold. It is assumed that the replacement threshold for the developer cartridge 200 is smaller than that for the drum cartridge 210. This is because it is assumed that two or more developer cartridges 200 are used for one drum cartridge 210.

Then, in step S5, the control unit 101 displays a message on the operation/display panel 51 prompting the replacement of cartridges whose usage information exceeds the replacement prompt threshold. Based on the usage information (second information) of the drum cartridge 210 from memory m1, the control unit 101 instructs the notification device to issue a notification regarding the prompting of replacement of the drum cartridge 210 (photosensitive drum 1). Furthermore, based on the usage information (first information) of the developer cartridge 200 from memory m2, the control unit 101 instructs the notification device to issue a notification regarding the prompting of replacement of the developer cartridge 210 (developer roller 4). Here, a notification prompting replacement can be a message informing the user that the unit has reached the end of its lifespan, or a message directly urging replacement. Whether direct or indirect, any message prompting replacement functions as a replacement prompt.

In step S5 of Figure 5(a), the main reason for the message prompting replacement is the deterioration of the toner 9 in the developing cartridge 200 due to repeated friction, assuming that there is still toner 9 remaining. In this case, although uneven halftone images occur due to the deterioration of toner 9, there are no major problems with the output of text images such as characters, so the user can choose to continue the image formation operation. When the user instructs to continue the image formation operation via the operation/display panel 51, the flowchart in Figure 5(b) is executed (S11). The flowchart in Figure 5(b) will be explained below. Note that the processing in steps S12 and S13 is the same as in steps S2 and S3 of Figure 5(a), so a detailed explanation will be omitted.

The control unit 101 reads and references the protection warning timing table for the drum cartridge 210 from the ROM 112 (S14). The contents of the table are shown in Table 1, described later. The information acquired by the control unit 101 in S12 corresponds to one of the vertical axes in Table 1, and the information acquired by the control unit 101 in S13 corresponds to one of the horizontal axes in Table 1.

In the image-forming units SY, SM, SC, and SK, if the combination of information corresponding to the usage amount of the drum cartridge 210 and the developing cartridge 200 is determined by the table referenced in S14 to be the timing for issuing a protection warning for the drum cartridge 210 (S5: YES), the control unit 101 temporarily suspends the image-forming operation (S16). For example, if the timing for issuing a protection warning for the drum cartridge 210 is reached for the image-forming unit SY, the control unit 101 temporarily suspends the image-forming operation, including for the image-forming units SM, SC, and SK, which have not yet reached the timing for issuing a protection warning.

On the other hand, if the conditions for issuing a protection warning for the drum cartridge 210 are not met in any of the image-forming units SY, SM, SC, or SK (S15: NO), the control unit 101 returns to process S12 after each image-forming operation is completed, and repeats the same process.

Then, the control unit 101, when the drum cartridge 210 protection warning timing is reached for the image-making unit, notifies the drum cartridge 210 protection warning via the display/operation panel 51 (S17).

Examples of the display/operation panel 51 include a display attached to the image forming apparatus 100, or a display for the image forming apparatus 100 and a personal computer. Furthermore, an example of a warning display related to the protection of the drum cartridge 210 of the image forming unit SY might be: "The drum cartridge (yellow) may be damaged. Please replace the developing cartridge (yellow)."

Furthermore, before the drum cartridge 210 protection warning is issued in step S17, the control unit 101 has already executed the flowchart in Figure 5(a) to cause the notification device to issue a notification regarding the prompting of each cartridge replacement. In other words, the processing in step S17 is performed after the notification regarding the prompting of each cartridge replacement has been issued. Then, when the drum cartridge protection warning is displayed, the flowchart in Figure 5 ends (S18).

As explained above, the control unit 101 refers to the table shown in Table 1 as, for example, a timing table for notifying a protection warning for the drum cartridge 210. The table in Table 1 is stored, for example, in ROM 112, O memory m1, or DT memory m2. Regarding the usage of the developer cartridge 200, a new cartridge before reaching the end of its lifespan is set to 0%, 100% is set when the usage reaches the threshold for prompting replacement, and values above 100% after reaching the end of its lifespan are displayed. Here, if the usage exceeds 100%, it means that the toner has deteriorated beyond its expected lifespan, and in Table 1, the term "deterioration level" is used for the vertical and horizontal axis items.

[Drum Cartridge Protection Warning Table]
The vertical axis of the drum cartridge 210 represents the degree of deterioration, which is a percentage obtained by dividing the information acquired by the control unit 101 in S12 by a predetermined value relating to the photosensitive drum 1, either by the cumulative number of rotations or the cumulative rotation time of the photosensitive drum 1. The degree of deterioration of the developer cartridge 200 at the time of the warning is a percentage obtained by dividing the information acquired by the control unit 101 in S13 by a predetermined value relating to the developer roller 4, either by the cumulative number of rotations or the cumulative rotation time of the developer roller 4. Alternatively, the degree of deterioration of the developer cartridge 200 may be calculated from the cumulative number of rotations of the developer roller and the amount of toner used, and expressed as a percentage of the friction (degree of damage) received from the components related to the toner 9. Note that the vertical and horizontal axes of the drum cartridge protection warning notification table are not limited to percentage values and can be appropriately replaced with any information corresponding to the amount of usage described above.

For example, if the usage of drum cartridge 210 is between 0% and 33%, and the usage of developer cartridge 200 is 161% or more, a protection warning for drum cartridge 210 will be issued. Also, if the usage of drum cartridge 210 is between 67% and 100%, and the usage of developer cartridge 200 is 121% or less, a protection warning for drum cartridge 210 will be issued. As shown in Table 1, the timing of the protection warning becomes earlier as the usage of drum cartridge 210 and developer cartridge 200 increases.

Here, we evaluated the occurrence of vertical streaks due to damage to the cleaning element under various usage levels of the drum cartridge 210 and the developer cartridge 200. As a common condition, for each usage level of the drum cartridge 210 and the developer cartridge 200, 2000 horizontal line images with a print density of 1% for each color were printed as durability images. As an evaluation image for cleaning performance, halftone images of each color with a print density of 25% were printed, and image defects (vertical streaks) were confirmed. The installation environment of the image forming apparatus 100 was 23°C and 50% humidity.

In Table 2, "○" indicates no vertical streak image occurrence, and "×" indicates vertical streak image occurrence. As shown in Table 2, when the usage amounts of the drum cartridge 210 and the developer cartridge 200 were measured before the protection warning notification for the drum cartridge 210, no vertical streak images occurred. However, when evaluated after the protection warning notification for the drum cartridge 210, vertical streak images occurred. At the location where the vertical streak image occurred, the cleaning blade 6 showed chipping of the blade edge.

As explained above, using the configuration of Example 1, even if the developing cartridge 200 is used again after a replacement prompt, a protection warning for the drum cartridge 210 can be issued at an appropriate time. Therefore, the occurrence of vertical streaks due to damage to the cleaning blade 6 can be prevented.

In this embodiment, if the developing unit continues to be used after a replacement prompt has been issued, image defects such as toner fouling can be prevented by correcting the amount of wear on the photosensitive drum of the latent image unit. Furthermore, by controlling the electrostatic bias based on the corrected amount of drum wear, toner fouling can be prevented with greater precision. Note that the image forming apparatus, drum cartridge, developing cartridge, and block diagram used in this embodiment are the same as in Embodiment 1, so a detailed explanation is omitted.

Furthermore, if the developing unit is used beyond its recommended lifespan, even if the cleaning blade does not break, the increased frictional resistance between the photosensitive drum and the cleaning blade may accelerate the wear speed of the dielectric layer on the photosensitive drum's surface. This can lead to inaccuracies in the calculation of the remaining thickness of the photosensitive drum's dielectric layer, resulting in inaccurate bias applied to the charging device and potentially causing image defects such as toner fouling. Therefore, if the developing unit is used beyond its lifespan, the calculation of the wear speed of the dielectric layer on the photosensitive drum's surface must be corrected accordingly.

[Process for correcting drum wear on a drum cartridge]
The process up to the drum wear amount correction control of the drum cartridge 210 in Example 2 will be explained using the flowchart in Figure 7. Note that the flowchart in Figure 5 explained in Example 1 is assumed to be performed separately from the flowchart in Figure 7. That is, the flowchart in Figure 7 shows the processing performed by the control unit 101 for the same combination of developing cartridge 200 and drum cartridge after the notification device 51, which provides notification regarding the promotion of replacement of the developing cartridge 200, has performed the flow in Figure 5.

After the image forming apparatus 100 is powered on, or after the cartridge replacement door is opened or closed, the flow shown in Figure 7 begins when the image forming apparatus 100 becomes operational (S201).

First, the control unit 101 communicates with the O memory m1 mounted on the drum cartridge 210 via the drum memory communication unit 515, and obtains information corresponding to the usage amount of the drum cartridge 210 from each of the O memory m1 of the image-making units SY, SM, SC, and SK (S202).

Next, the control unit 101 communicates with the DT memory m2 mounted on the developing cartridge 200 via the developing memory communication unit 516, and obtains information corresponding to the amount of developing cartridge 200 used from the respective DT memories m2 of the image-making units SY, SM, SC, and SK (S203). The information corresponding to each usage amount is as described in Example 1. A detailed explanation is omitted here.

Next, the control unit 101 reads and references a table from the ROM 112 regarding the amount of surface wear on the photosensitive drum of the drum cartridge 210 (S204). The amount of surface wear on the photosensitive drum is calculated using equation (1), which will be described later.

The control unit 101, based on the information acquired in S203 in the image-forming units SY, SM, SC, and SK, determines whether the information corresponding to the usage amount of the developing cartridge 200 indicates that the replacement reminder threshold has been reached. The information corresponding to the usage amount of the drum cartridge 210 and the information corresponding to the usage amount of the developing cartridge 200 are as described in Example 1.

Then, if the control unit 101 determines YES in S205, the control unit 101 corrects the drum surface wear amount obtained in S204 according to the information on the amount of developing cartridge used (S206). The control unit 101 subtracts this corrected drum surface wear amount from the initial drum film thickness to calculate the corrected drum film thickness.

For example, if the information regarding the amount of developing cartridge used in the image-forming unit SY reaches the threshold for prompting replacement of the developing cartridge, the control unit 101 corrects the amount of surface wear on the drum. The contents of the correction table are shown in Table 3, which will be described later. The information acquired by the control unit 101 in S203 corresponds to one of the vertical axes in Table 3.

Step S206 is also performed when the same combination of developing cartridge 200 and drum cartridge 210, which was the notification target in the flowchart of Figure 5, is the target of the determination. In this case, the control unit 101 refers to the table in Table 3 (described later) and estimates the amount of drum surface wear for a predetermined usage amount of the developing unit 200 after the notification regarding replacement promotion to be larger than the amount of drum surface wear for the same predetermined usage amount before the notification. In other words, the control unit 101 calculates the amount of drum surface wear for a predetermined usage amount of the developing unit 200 using a larger coefficient value after the development unit replacement promotion. Note that the predetermined usage amount can be, for example, the rotation speed of the developing roller 4, the driving time of the developing drum unit 200, or any information correlated with them, such as the number of printed pages.

Subsequently, the control unit 101 sets the charging bias based on the corrected drum film thickness, which reflects the corrected amount of wear (S207). For example, suppose that the corrected actual drum film thickness of the drum cartridge 210 described above is approximately 1 μm thinner than before correction. In this case, the control unit 101 increases the charging bias by approximately 10 V based on the corrected drum film thickness and applies it so that the potential (Vd) of the white area on the drum surface remains the same.

Furthermore, the setting of the charge application bias in step S207 may be performed by pre-preparing a table of drum surface wear amount and charge application bias value, and the control unit 101 referring to that table. In that case, in step S207, the control unit 101 does not need to calculate the drum film thickness by subtracting the corrected drum surface wear amount from the initial drum film thickness.

Returning to the flowchart explanation, the image forming apparatus 100 then proceeds to the image forming operation and executes printing based on the bias settings changed by the control unit 101.

On the other hand, if the development cartridge 200 replacement threshold has not been reached in each of the image-forming units SY, SM, SC, and SK (S205: NO), the control unit 101 does not perform any specific abrasion correction. That is, the control unit 101 sets the charge application bias based on the drum film thickness due to the drum surface abrasion without correction.

The control unit 101 then proceeds to image formation operation with the set charge application bias and executes printing. When the printing operation is complete, the flow shown in Figure 7 ends (S208).

The control unit 101 refers to the table shown in Table 1 of Embodiment 1 as, for example, the timing table for notifying a protection warning for the drum cartridge 210. Regarding the degradation level (usage) of the developer cartridge 200, a new cartridge before reaching the end of its lifespan is set to 0%, the end of its lifespan is set to 100%, and usage after reaching 100% is displayed as a value of 100% or higher. The same applies to the degradation level of the drum cartridge in Table 1.

[Drum wear correction table]
As previously described in Example 1, information regarding the usage of the drum cartridge 210 and the developing cartridge 200 is derived from the cumulative number of rotations or cumulative rotation time information for each. Here, we will explain the amount of surface wear of the photosensitive drum. On the surface of the photosensitive drum, at least a conductive layer, a charge generation layer as a photosensitive layer, and a charge transport layer are sequentially laminated on a conductive support. The photosensitive drum used in this case is constructed by sequentially laminating a conductive layer, an underlayer that prevents charge injection, a charge generation layer as a photosensitive layer, and a charge transport layer that transports charge on a conductive support. Film thickness is the distance from the surface of the conductive support to the surface of the charge generation layer. The amount of surface wear of the drum can generally be calculated from the following formula (1).
K = αX + βY + γZ ... (1)

Here, α is the coefficient of surface abrasion per unit time for the photosensitive drum during idle rotation (without charge application and without development contact), and X represents the operating time of this operation. Also, β is the coefficient of surface abrasion per unit time for the rotation of the photosensitive drum when charge is applied (without development contact), and Y represents the operating time of this operation. Also, γ is the coefficient of surface abrasion per unit time for the rotation of the photosensitive drum when a charge voltage is applied and development contact is present, and Z represents the operating time of this operation. The control unit 101 then calculates the amount of surface abrasion on the drum from these three coefficients (α, β, γ) and their respective operating times (X, Y, Z). The actual film thickness is then calculated from the following equation (A).
Drum film thickness = Initial film thickness - Drum wear amount (K) ... (A)

The calculated values are stored in the drum film thickness information within the O-memory m1 of the drum cartridge 210, allowing for the calculation of the remaining film thickness at any time.

In this embodiment 2, the wear coefficient is corrected when the developing cartridge 200 is used even after reaching the end of its lifespan. The drum correction amount for each developing cartridge's degree of deterioration (usage) is explained using the table in Table 3. The control unit 101, for example, refers to the table in Table 3 when calculating the drum wear amount of the drum cartridge 210. The table in Table 3 is stored, for example, in ROM 112, O memory m1, or DT memory m2. The display of the developing cartridge 200's degree of deterioration (usage) is the same as in embodiment 1.

Similar to Example 1, when the development cartridge usage reaches the threshold for replacement (100% usage), the display/operation panel 51 will notify the user that the cartridge has reached the end of its lifespan. Upon receiving this notification, the user can choose whether to continue the image formation process. In this case, although there may be some unevenness in the halftone image due to toner 9 degradation, there are no major problems with the output of text images such as characters. Therefore, the user is given the option to continue the image formation process.

Here, as shown in Table 3, even after the development cartridge usage reaches the threshold for prompting replacement, drum wear correction is performed according to the information (degree of deterioration) corresponding to the amount of development cartridge used. As shown in the table, the degree of correction for drum wear increases as the amount of development unit usage (degree of deterioration) and the drum cartridge usage (degree of deterioration) increase. By correcting the drum wear amount based on Table 3, the actual amount of drum wear can be accurately determined, and an appropriate charging bias can be applied.

Table 4 shows the results of an evaluation of the occurrence of toner fouling in images based on the amount of developing cartridge used. As an evaluation condition, the drum cartridge 210 was used at 100%, and 5000 sheets of horizontal line images with a print density of 1.0% for each color were fed through the paper. Toner fouling was evaluated by printing a solid white image and checking for toner fouling on the image. The image forming apparatus 100 was installed in a low-temperature, low-humidity environment of 15°C and 10% humidity.

Table 4 shows the evaluation results under conditions without considering drum wear correction, as a comparative example. "○" indicates no toner fouling, "△" indicates deterioration of fouling on the drum, but no problems on solid white images. "×" indicates toner fouling occurred on solid white images.

As these results show, both systems performed without problems as long as the usage of the developer cartridge 200 had not yet reached the threshold for prompting replacement. However, when evaluated after the threshold was reached, toner fouling occurred. Further investigation at the time of the toner fouling revealed that a shift in the charge bias caused Vd to decrease, resulting in a narrower contrast with the developer bias (hereinafter referred to as Vback) compared to the desired setting. Note that Vback refers to the difference between Vd (the potential of the white area on the drum surface) and the developer bias (the bias applied to the developer roller).

Figure 8 shows the Vback dependence of toner fouling after the development cartridge usage reaches the threshold for replacement. With a Vback setting based on a normal latent image setting, the setting is A in the figure, and no toner fouling occurs. As explained above, toner fouling could be suppressed by performing drum wear correction. As a comparative example, under conditions where drum wear was not considered, a deviation of up to approximately 1 μm was observed, depending on the number of sheets fed. This was found to be a deviation from the actual drum film thickness, resulting in setting B in the figure.

[Potential characteristics of the surface film thickness of a drum cartridge]
Generally, as the surface film thickness of the drum wears down and becomes thinner, the bright area potential (Vd) and the dark area potential (VL) after the latent image tend to increase even when the same charging bias is applied. In addition, a decrease in Vd due to dark attenuation occurs when moving from the charging position to the developing position. This can be explained by the relationship between capacitance.

Equation (2) shows the relationship between capacitance.
Q = CV = ε0εγ×S/d...(2)
Q: Electric charge (C), C: Electrostatic charge (F), V: Electric potential (V), ε₀εγ: Dielectric constant, S: Area ( ^m² )
d: Indicates distance (m).

From this, the charge Q is proportional to the electric potential V and inversely proportional to the distance d. In other words, the relationship between capacitance and current is inversely proportional to the surface thickness of the drum.

Here, we will explain the potential and fouling characteristics of the drum surface film thickness using Figure 9. The horizontal axis represents the drum surface film thickness (μm), and the vertical axis represents the toner fouling (%). The solid line shows the effect of toner fouling at a Vd = -600V setting, while dashed lines 1 and 2 show the trends at -500V and -400V settings, respectively. As can be seen from Figure 9, the toner fouling deteriorates rapidly as the drum surface film thickness decreases below 10 μm. Furthermore, it is known that this tendency is more pronounced at higher absolute values of the Vd potential. In other words, when the surface film thickness is 10 μm or less, image defects such as toner fouling are more likely to occur.

Based on this experience, the drum cartridge is designed so that the drum's surface film thickness reaches approximately 10-11 μm, which triggers the drum's lifespan (replacement reminder). However, after the developer cartridge's usage reaches the replacement reminder threshold, the drum wear rate increases for the same rotation, requiring a correction to account for the amount of drum film wear.

As described above, even if a user continues to use a developer cartridge 200 whose usage has reached the replacement threshold, the amount of drum wear on the drum cartridge 210 can be corrected. This allows the control unit 101 (CPU 11) to select and control an appropriate charge application bias setting according to the corrected drum film thickness, thereby suppressing the occurrence of toner fogging.

[Variations]
The image forming units SY, SM, SC, and SK of the image forming apparatus 100 in Examples 1 and 2 are composed of a drum cartridge 210 and a developer cartridge 200, but are not limited to this. The method can also be applied to a so-called toner replenishment system in which the toner container containing the toner 9 is a separate unit (toner cartridge) among the components of the developer cartridge 200. For example, in the case of a toner replenishment system, a toner cartridge (developer unit) that contains the toner 9 and is detachable from the main body of the image forming apparatus 100 is separated from the developer cartridge 200. In the case of a toner replenishment system, the same effect can be obtained by changing the conditions for information corresponding to the amount of developer cartridge 200 used in determining protection warnings to conditions for information corresponding to the amount of toner cartridge used. In this case, a non-volatile memory as a DT memory m2 or third memory is provided in the toner cartridge, and information corresponding to the amount of toner cartridge used is stored in the DT memory m2 or third memory provided in the toner cartridge.

Furthermore, while Examples 1 and 2 show configurations where O memory m1 is provided in the drum cartridge 210 and DT memory m2 is provided in the developing cartridge 200, the system is not limited to these configurations. O memory m1 and DT memory m2 may be provided in the main body of the image forming apparatus 100. A third memory may also be provided in the main body of the image forming apparatus 100. In this case, drum cartridge identifiers and developing cartridge identifiers, respectively, which can identify individual drum cartridges 210 and developing cartridges 200, are stored in O memory m1 and DT memory m2. The control unit 101 stores the information corresponding to the usage amounts described above in the third memory of the main body of the image forming apparatus 100, and manages it in the same manner as described above.

1. Photoconductor drum 2. Charging roller 4. Developing roller 5. Toner supply roller 6. Cleaning blade (contact member)
9 Toner 11 Drum cartridge frame 31 Intermediate transfer belt 34 Fixing device 100 Image forming apparatus 101 Control unit 102 Temperature sensor (environmental detection means)
200 Developer Cartridge (Developer Unit)
210 Drum Cartridge (Latent Image Unit)
m1 O memory (first memory)
m2 DT memory (second memory)

Claims (11)

An image forming apparatus in which a latent image unit and a developing unit can be attached to and detached from the main body of the apparatus,
The aforementioned latent image unit is
A rotatable image carrier on which an electrostatic latent image is formed,
The system includes a cleaning member that contacts the image carrier to remove the developer from the surface of the image carrier,
The aforementioned developing unit is
The image carrier has a developer carrier for developing the electrostatic latent image formed on the image carrier with a developer ,
Furthermore, the image forming apparatus is
Control unit and
An notification device that provides notification regarding the promotion of replacement of the aforementioned developing unit,
Equipped with,
The control unit, after the notification device has issued a notification regarding the promotion of replacement, acquires first information corresponding to the amount of use of the developing unit, and based on the acquired first information, causes the notification device to issue a warning regarding the protection of the latent image unit.
The control unit acquires second information corresponding to the amount of use of the latent image unit, and causes the notification device to notify a warning regarding the protection of the latent image unit based on the first information and the second information.
The control unit accelerates the timing at which it notifies the notification device of a warning regarding the protection of the latent image unit, even if the amount of the latent image unit used is the same, and accelerates the timing at which it notifies the notification device of a warning regarding the protection of the latent image unit, even if the amount of the development unit used is the same, and accelerates the timing at which it notifies the notification device of a warning regarding the protection of the latent image unit, even if the amount of the development unit used is the same, and the amount of the latent image unit used is the same.
An image forming apparatus characterized by the following: The system comprises first and second image-forming units, including the latent image unit and the developing unit,
The image forming apparatus according to claim 1, characterized in that the control unit acquires first information corresponding to the amount of use of the developing unit in the first and second image forming units, and causes the notification device to notify a warning regarding the protection of the latent image unit based on the acquired first information. The developing unit has a first memory in which the first information is stored,
The image forming apparatus according to claim 1, characterized in that the control unit acquires the first information from the first memory. The latent image unit has a second memory in which the second information is stored,
The image forming apparatus according to claim 1, characterized in that the control unit acquires the second information from the second memory. The image forming apparatus according to any one of claims 1 to 4, characterized in that the notification device is a display device of the image forming apparatus. The image forming apparatus according to any one of claims 1 to 5, characterized in that the developer supported by the developer carrier has externally added particles. The image forming apparatus according to any one of claims 1 to 6, characterized in that the cleaning member is a blade member whose tip, extending in the opposite direction to the direction of movement of the image carrier relative to the cleaning member, abuts against the surface of the image carrier. An image forming apparatus in which a latent image unit and a developing unit can be attached to and detached from the main body of the apparatus,
The aforementioned latent image unit is
A rotatable image carrier on which an electrostatic latent image is formed,
The system includes a cleaning member that contacts the image carrier to remove the developer from the surface of the image carrier,
The aforementioned developing unit is
The image carrier has a developer carrier for developing the electrostatic latent image formed on the image carrier with a developer ,
Furthermore, the image forming apparatus is
means of charging,
Control unit and
An notification device that provides notification regarding the promotion of replacement of the aforementioned developing unit,
Equipped with,
The control unit acquires first information corresponding to the amount of use of the developing unit, and based on the acquired first information, causes the notification device to issue a notification regarding the promotion of replacement of the developing unit.
After notification regarding the promotion of replacement is given, the control unit estimates, for the same combination of the developing unit and the latent image unit, that the amount of film thickness removal on the surface of the image carrier relative to a predetermined amount of use of the latent image unit is greater than the amount of film thickness removal relative to the predetermined amount of use before notification regarding the promotion of replacement is given.
The image forming apparatus is characterized in that the control unit sets a charging bias to the charging means based on the estimated amount of film thickness removal. The image forming apparatus according to claim 8, characterized in that as the amount of developing unit used increases, the amount of film thickness removed relative to a predetermined amount of developing unit used becomes greater. The image forming apparatus according to claim 8 or 9, characterized in that as the amount of latent image unit used increases, the amount of film thickness removal relative to a predetermined amount of development unit used increases. The image forming apparatus according to any one of claims 8 to 10, characterized in that the image carrier has at least a conductive layer, a charge generation layer as a photosensitive layer, and a charge transport layer sequentially laminated on a conductive support, and the film thickness of the image carrier is the distance from the surface of the conductive support to the surface of the charge generation layer.