Image forming apparatus

Abstract

To prompt replacement of a photoreceptor unit having a photoreceptor and a charging member at appropriate timing.SOLUTION: An image forming apparatus includes a photosensitive member unit including a photosensitive member on which an electrostatic latent image is formed and a charging member that charges the photosensitive member, a developing device that develops the electrostatic latent image formed on the photosensitive member using a developer containing a toner and a carrier, a replenishment container that stores a replenishment developer to be replenished to the developing device, a storage unit that is provided in the replenishment container and stores information on a coverage ratio of an external additive to the toner of the replenishment developer stored in the replenishment container, a display unit, and a control unit that controls the display unit to display information on replacement of the photosensitive member unit based on the information on the coverage ratio stored in the storage unit.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus equipped with a photosensitive unit having a photosensitive member and a charging member. [Background technology]

[0002] A contact charging method is known in which a charging member such as a charging roller is brought into contact with the surface of a photosensitive member such as a photosensitive drum, and a voltage is applied to the charging member to charge the photosensitive member. In the contact charging method, a DC voltage alone or a voltage obtained by superimposing a DC voltage and an AC voltage is applied to the charging member.

[0003] Patent Document 1 describes that the life of a photosensitive member is detected based on the cumulative rotation time of the photosensitive member corresponding to the application of a DC voltage and the cumulative AC voltage application time during which an AC voltage is applied. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-236437 Summary of the Invention [Problem to be solved by the invention]

[0005] The following two factors are cited as the main causes of the shortened lifespan of a photoreceptor unit that has a photoreceptor and a charging member. The first factor is wear of the photoreceptor, which is caused by discharge due to the application of voltage to the charging member, causing the charge transport layer on the surface of the photoreceptor to deteriorate, and the surface of the photoreceptor is scraped off by the cleaning blade, making it unable to be charged. The second factor is contamination of the charging member, which occurs when the charging member becomes dirty due to repeated image formation, causing uneven discharge and impairing the uniformity of charging.

[0006] It is known that these phenomena, such as photoreceptor wear and charging member contamination, are significantly affected by external additives added to toner. The more external additives that reach the cleaning blade via the photoreceptor, the stronger the friction force of the cleaning blade tends to be at the point where the cleaning blade contacts the photoreceptor. Therefore, the more external additives that reach the cleaning blade via the photoreceptor, the more the photoreceptor wears, and there is a risk that the life of the photoreceptor (life of the photoreceptor unit) will be shortened.

[0007] Furthermore, the more external additive that reaches the charging member via the photosensitive member, the more contamination of the charging member progresses in the area where the charging member is close to the photosensitive member, which may shorten the life of the charging member (life of the photosensitive unit).On the other hand, if there is less external additive that reaches the cleaning blade or charging member via the photosensitive member, the wear of the photosensitive member and the contamination of the charging member progress more slowly, which can prevent the life of the photosensitive unit from being shortened.

[0008] However, when the toner manufacturing conditions vary depending on the toner manufacturing lot, the amount of external additive carried by the toner matrix may vary. If the amount of external additive carried by the toner matrix varies, the life of the photosensitive unit may vary depending on the amount of external additive carried by the toner matrix, even if the cumulative rotation time of the photosensitive body corresponding to the application of DC voltage and the cumulative AC voltage application time are the same.

[0009] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an image forming apparatus that can prompt replacement of a photosensitive unit having a photosensitive member and a charging member at an appropriate time. [Means for solving the problem]

[0010] In order to achieve the above object, an image forming apparatus according to one aspect of the present invention comprises the following configuration: a photosensitive unit having a photosensitive member on which an electrostatic latent image is formed and a charging member that charges the photosensitive member, a developing device that develops the electrostatic latent image formed on the photosensitive member using a developer containing toner and a carrier, a supply container that stores supply developer to be replenished to the developing device, a memory unit provided in the supply container that stores information regarding a coverage rate of an external additive to the toner of the replenishment developer stored in the supply container, a display unit, and a control unit that controls the display unit to display information regarding replacement of the photosensitive unit based on the information regarding the coverage rate stored in the memory unit. [Effects of the Invention]

[0011] According to the present invention, it is possible to prompt replacement of a photosensitive unit having a photosensitive member and a charging member at an appropriate timing. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing a configuration of an image forming apparatus according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing the configuration of an image forming unit according to the first embodiment. [Figure 3] 1A and 1B are a cross-sectional view and a top view showing the configuration of a developing device according to a first embodiment. [Figure 4] FIG. 2 is a cross-sectional view showing the configuration of a photosensitive unit according to the first embodiment. [Figure 5] FIG. 2 is a block diagram showing a part of a control system of the image forming apparatus according to the first embodiment. [Figure 6] 10 is a flowchart showing a series of processes related to calculation of an integrated driving distance of a photosensitive drum. [Figure 7] 5 is a flowchart showing a series of processes relating to life detection of a photosensitive unit according to the first embodiment. [Figure 8] 10 is a flowchart showing a series of processes related to calculation of an integrated driving distance of the charging roller. [Figure 9]10 is a flowchart showing a series of processes relating to life detection of a photosensitive unit according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the present invention, and not all of the combinations of features described in the first embodiment are necessarily essential to the solution of the present invention. The present invention can be implemented in a variety of applications, such as printers, various printing machines, copiers, fax machines, and multifunction machines.

[0014] [First embodiment] (Configuration of image forming device) First, the overall configuration and operation of the image forming apparatus will be described. Fig. 1 is a cross-sectional view showing the configuration of an image forming apparatus 100 according to the first embodiment.

[0015] The image forming apparatus 100 is a full-color electrophotographic image forming apparatus using an intermediate transfer system and has four photosensitive drums 1. In the first embodiment, the process speed, which corresponds to the surface movement speed of the photosensitive drums 1 and the intermediate transfer belt 51, is 150 mm / sec.

[0016] Image forming apparatus 100 has a plurality of image forming units, namely, first, second, third, and fourth image forming units Sa, Sb, Sc, and Sd. Each image forming unit Sa, Sb, Sc, and Sd is for forming an image of each color: yellow (Y), magenta (M), cyan (C), and black (Bk). The configurations of each image forming unit Sa to Sd are essentially the same except for the different colors of toner used. Therefore, unless a distinction is required, the suffixes a, b, c, and d, which are added to reference numerals in the drawings to indicate that the element is provided for a particular color, will be omitted and the image forming units will be generally described.

[0017] The image forming station S has a photosensitive drum 1 as an image carrier. Around the photosensitive drum 1, a charging roller 2 as a primary charging means, a laser scanner 3 as an exposure means, a developing device 4 as a developing means, a drum cleaner 6 as a drum cleaning means, and the like are sequentially arranged along the rotation direction of the photosensitive drum 1. In addition, an intermediate transfer belt 51, which is a rotatable belt member serving as an intermediate transfer member, is arranged adjacent to the photosensitive drums 1a to 1d of each of the image forming stations Sa to Sd.

[0018] The intermediate transfer belt 51 is stretched over a plurality of support members, including a drive roller 52, a steering roller 55, a secondary transfer inner roller 56, and an upstream regulating roller 58. The steering roller 55 also has the function of applying a tensioning force for tensioning the intermediate transfer belt 51, and both ends of the steering roller 55 are biased substantially leftward in FIG. 1 by a spring biasing means (not shown). A driving force is transmitted to the intermediate transfer belt 51 by the drive roller 52, which is a belt driving means, and the intermediate transfer belt 51 moves in a circular motion in the direction of arrow R3 shown in FIG.

[0019] Primary transfer rollers 53a to 53d as primary transfer members are arranged at positions facing the photosensitive drums 1a to 1d on the inner circumferential surface side of the intermediate transfer belt 51. The primary transfer rollers 53a to 53d are urged toward the photosensitive drums 1a to 1d via the intermediate transfer belt 51, and primary transfer portions (primary transfer nips) N1a to N1d are formed where the photosensitive drums 1a to 1d come into contact with the intermediate transfer belt 51.

[0020] Furthermore, a secondary transfer outer roller 57 serving as a secondary transfer member is disposed at a position facing the secondary transfer inner roller 56 on the outer peripheral surface side of the intermediate transfer belt 51. The secondary transfer outer roller 57 comes into contact with the outer peripheral surface of the intermediate transfer belt 51 to form a secondary transfer portion (secondary transfer nip) N2. Images formed on the photosensitive drums 1a-1d at the image forming portions Sa-Sd are sequentially transferred in multiple layers onto the intermediate transfer belt 51, which moves adjacent to the photosensitive drums 1a-1d. Thereafter, the images transferred onto the intermediate transfer belt 51 are further transferred to a transfer material P such as paper at the secondary transfer portion N2.

[0021] The fixing device 7 has a rotatably disposed fixing roller 71 and a pressure roller 72 that rotates while being in pressure contact with the fixing roller 71. A heater 73 such as a halogen lamp is disposed inside the fixing roller 71. The temperature of the surface of the fixing roller 71 is adjusted by controlling the voltage supplied to the heater 73. When the transfer material P is conveyed to the fixing device 7, as the transfer material P passes between the fixing roller 71 and the pressure roller 72, which rotate at a constant speed, the transfer material P is pressurized and heated from both the front and back sides of the transfer material P at a substantially constant pressure and temperature. As a result, the unfixed toner image on the surface of the transfer material P is melted and fixed to the transfer material P. In this way, a full-color image is formed on the transfer material P.

[0022] (Configuration of image forming unit) Next, a detailed description will be given of the image forming unit S. Fig. 2 is a cross-sectional view showing the configuration of the image forming unit S according to the first embodiment.

[0023] The photosensitive drum 1 is rotatably supported by the main body of the image forming apparatus 100. The photosensitive drum 1 is a cylindrical electrophotographic photosensitive member basically composed of a conductive substrate 11 made of aluminum or the like and a photoconductive layer 12 formed on the outer periphery of the photosensitive drum 1. The photosensitive drum 1 has a support shaft 13 at the center of the photosensitive drum 1. The photosensitive drum 1 is driven to rotate around the support shaft 13 in the direction of arrow R1 shown in FIG. 2 by a driving means. In the first embodiment, a φ30 organic photosensitive semiconductor photosensitive drum is used, but an amorphous silicon photosensitive drum may also be used.

[0024] As shown in Fig. 2, a charging roller 2 serving as a primary charging means is disposed above the photosensitive drum 1. The charging roller 2 comes into contact with the surface of the photosensitive drum 1 and uniformly charges the surface of the photosensitive drum 1 to a predetermined polarity and potential. The charging roller 2 has a conductive core 21 disposed at the center of the charging roller 2, a low-resistance conductive layer 22 formed on the outer periphery of the charging roller 2, and a medium-resistance conductive layer 23, and is configured in a roller shape as a whole.

[0025] The charging roller 2 is rotatably supported at both ends of a core metal 21 by bearing members, and is disposed parallel to the photosensitive drum 1. The bearing members at both ends of the core metal 21 are urged toward the photosensitive drum 1 by pressing means. As a result, the charging roller 2 is pressed against the surface of the photosensitive drum 1 with a predetermined pressing force.

[0026] 2, the charging roller 2 rotates in the direction of arrow R2 in accordance with the rotation of the photosensitive drum 1 in the direction of arrow R1. A charging bias voltage is applied to the charging roller 2 by a charging bias power supply 24 as a charging bias output means. As a result, in the first embodiment, the surface of the photosensitive drum 1 is uniformly charged to −600 V.

[0027] Furthermore, a laser scanner 3 is disposed downstream of the charging roller 2 in the rotation direction of the photosensitive drum 1. The laser scanner 3 scans while turning a laser beam on and off based on image information, exposing the surface of the photosensitive drum 1. As a result, an electrostatic image (latent image) corresponding to the image information is formed on the surface of the photosensitive drum 1. The wavelength λ of the laser scanner 3 used in the first embodiment is 780 nm, and the resolution of the laser scanner 3 is 600 dpi.

[0028] Furthermore, a developing device 4 is disposed downstream of the laser scanner 3 in the rotation direction of the photosensitive drum 1. The developing device 4 visualizes the electrostatic image formed on the photosensitive drum 1. A replenishing device 9 replenishing toner to the developing device 4. Details of the developing device 4 and the replenishing device 9 will be described later with reference to FIG.

[0029] 2, a primary transfer roller 53 is disposed below the photosensitive drum 1 and downstream of the developing device 4 in the rotation direction of the photosensitive drum 1. The primary transfer roller 53 is composed of a core 531 and a conductive layer 532 formed in a cylindrical shape on the outer peripheral surface of the core 531. Both ends of the primary transfer roller 53 are biased toward the photosensitive drum 1 by pressing members such as springs. As a result, the conductive layer 532 of the primary transfer roller 53 is pressed against the surface of the photosensitive drum 1 via the intermediate transfer belt 51 with a predetermined pressing force. A primary transfer bias power supply 54 serving as a primary transfer bias output means is connected to the core 531.

[0030] A primary transfer portion N1 is formed between the photosensitive drum 1 and the primary transfer roller 53. The intermediate transfer belt 51 is sandwiched in the primary transfer portion N1. The primary transfer roller 53 contacts the inner circumferential surface of the intermediate transfer belt 51 and rotates as the intermediate transfer belt 51 moves. During image formation, a primary transfer bias voltage of a polarity (second polarity: positive polarity in the first embodiment) opposite to the normal charging polarity of the toner (first polarity: negative polarity in the first embodiment) is applied to the primary transfer roller 53 by a primary transfer bias power supply 54. An electric field is formed between the primary transfer roller 53 and the photosensitive drum 1 in a direction that moves toner of the first polarity from the surface of the photosensitive drum 1 toward the intermediate transfer belt 51. As a result, the toner image formed on the surface of the photosensitive drum 1 is transferred (primary transfer) to the surface of the intermediate transfer belt 51.

[0031] Adherents such as toner remaining on the surface of the photosensitive drum 1 after the primary transfer process (primary transfer residual toner) are cleaned by a drum cleaner 6 (cleaning device). The drum cleaner 6 has a cleaning blade 61 as a drum cleaning member, a conveying screw 62, and a drum cleaner housing 63. The cleaning blade 61 is brought into contact with the photosensitive drum 1 at a predetermined angle and pressure by a pressure means. As a result, the toner remaining on the surface of the photosensitive drum 1 is scraped and removed from the surface of the photosensitive drum 1 by the cleaning blade 61, and is collected in the drum cleaner housing 63. The collected toner is transported by the conveying screw 62 and discharged to a waste toner storage section.

[0032] (Configuration of developing device) Next, details of the developing device 4 will be described. Fig. 3(a) is a cross-sectional view showing the configuration of the developing device according to the first embodiment, and Fig. 3(b) is a top view showing the configuration of the developing device according to the first embodiment.

[0033] The developing device 4 has a developing container 40 that contains a two-component developer made up of non-magnetic toner and magnetic carrier. The weight ratio of the non-magnetic toner to the two-component developer contained in the developing container 40, i.e., the toner concentration, is approximately 10 wt%. This ratio is adjusted appropriately depending on the charge amount of the toner, the particle size of the carrier, or the configuration and usage conditions of the image forming apparatus 100, and does not necessarily have to follow this numerical value. Details of the two-component developer will be described later.

[0034] The developing device 4 has an opening in the development area facing the photosensitive drum 1, and a developing sleeve 41 is rotatably disposed so as to be partially exposed in this opening. A magnet roll 42, which is a magnetic field generating means, is disposed inside the developing sleeve 41 and is fixed so as not to rotate. The developing sleeve 41 rotates in the direction of arrow R4 in FIG. 3(a) during development. The developing sleeve 41 holds the developer contained in the developing container 40 in a layer, carries and transports it to the development area, and supplies the developer to the development area facing the photosensitive drum 1, where it develops the electrostatic latent image formed on the surface of the photosensitive drum 1 with toner. After developing the electrostatic latent image formed on the surface of the photosensitive drum 1, the developer is transported as the developing sleeve 41 rotates and is collected into the developing container 40.

[0035] The developing chamber 40a of the developer container 40 is provided with a developing screw 43 as a first developer stirring / transporting member. The developing chamber 40b of the developer container 40 is provided with an agitating screw 44 as a second developer stirring / transporting member. The developing screw 43 and the agitating screw 44 circulate the developer within the developer container 40 and mix and agitate it again. The developer circulates from the front to the back of FIG. 3(a) on the developing screw 43 side, and from the back to the front of FIG. 3(a) on the agitating screw 44 side. The developing screw 43 and the agitating screw 44 both have a central shaft diameter of 7 mm and an outer diameter of 14 mm, and rotate at a speed of 300 rpm. The distance between the developer container 40 and the developing screw 43 was set to 1 mm, and the distance between the developer container 40 and the agitating screw 44 was also set to 1 mm.

[0036] In the first embodiment, the developing sleeve 41 is arranged opposite the photosensitive drum 1 with a gap of 300 μm between them, and is arranged to rotate in the forward direction of the rotation of the photosensitive drum 1 (the direction of arrow R4 shown in Figure 3(a)) at 180% of the peripheral speed of the photosensitive drum 1.

[0037] The developing sleeve 41 is made of a metal such as aluminum or SUS and is formed into a cylindrical shape. The surface of the developing sleeve 41 is subjected to a blasting treatment, or to a plating treatment or coating treatment, thereby adjusting the developer transportability and frictional charge imparting properties. In the first embodiment, a metal sleeve with an aluminum surface subjected to a blasting treatment is used as the developing sleeve 41.

[0038] As described above, the magnet roll 42 having a plurality of magnetic poles as a magnetic field generating means is fixed and non-rotatable inside the developing sleeve 41. In the first embodiment, the magnet roll 42 having five magnetized magnetic poles is used.

[0039] As shown in Figure 3(a), the S1 pole is a regulating pole that regulates the amount of developer transported to the development area, the N1 pole is a developing pole that contributes to development, and the S2 pole is a transport pole that transports the developer. Also, as shown in Figure 3(a), the N2 pole is a repulsive pole that scrapes off the developer carried on the developing sleeve 41, and the N3 pole is an intake pole that causes the developer sent from the developing screw 43 to be carried on the developing sleeve 41.

[0040] The developing device 4 also has a regulating blade 45 as a developer amount regulating member that regulates the amount of developer carried on the developing sleeve 4. The regulating blade 45 is disposed facing the developing sleeve 41 with a constant gap between them across the longitudinal direction of the developing device 4. In the first embodiment, a flat, non-magnetic regulating blade 45 having a thickness of 1 mm is used as the regulating blade 45, but the shape of the regulating blade 45 is not limited to a flat plate shape, and the tip may be sharpened to a thickness of about 0.3 mm.

[0041] The amount of developer carried on the developing sleeve 41 and transported to the development zone is determined by various conditions, such as the shape of the regulating blade 45, the gap between the developing sleeve 41 and the regulating blade 45, the maximum value of the magnetic flux density of the regulating pole S1, and the position where the magnetic flux density of the regulating pole S1 is maximum. In the first embodiment, the gap between the developing sleeve 41 and the regulating blade 45 is set to 300 μm, and the amount of developer transported to the development zone is regulated so that the mass per unit area (M / S) is 30 mg / cm2.

[0042] With the above-described configuration, the developing sleeve 41 containing the magnet roll 42 carries the developer in the developing container 40 and transports it to a position facing the photosensitive drum 1, while forming a magnetic brush at the position facing the photosensitive drum 1. Then, the high-voltage power supply 401 of the image forming apparatus 100 applies a suitable developing bias to the developing sleeve 41, causing the developing device 4 to develop the electrostatic latent image formed on the surface of the photosensitive drum 1. In the first embodiment, the high-voltage power supply 401 applied a voltage obtained by superimposing an AC component with a frequency of 10 kHz and a peak-to-peak voltage Vpp of 1.8 kV and a DC component (Vdc) of -450 V, but the present invention is not limited to these values.

[0043] (two-component developer) As described above, in the first embodiment, a two-component developer made of non-magnetic toner and magnetic carrier is contained in the developing container 40. Here, the two-component developer made of non-magnetic toner and magnetic carrier will be described in detail.

[0044] As the magnetic carrier, for example, surface-oxidized or unoxidized metals such as iron, nickel, cobalt, manganese, chromium, rare earth elements, and alloys thereof, or oxide ferrites can be suitably used, and the manufacturing method of these magnetic particles is not particularly limited. In the first embodiment, ferrite particles coated with silicone resin are used as the magnetic carrier. This magnetic carrier has a saturation magnetization of 294 am when a magnetic field of 240 kA / m is applied. 2 / kg, and the specific resistance at an electric field strength of 3000V / cm is 1×10 7~8In addition, the magnetic carrier may be a resin magnetic carrier produced by polymerization using a binder resin, a magnetic metal oxide, and a non-magnetic metal oxide as starting materials.

[0045] The volume average particle size of the magnetic carrier was measured using a laser diffraction particle size distribution analyzer HEROS (manufactured by JEOL Ltd.) by dividing the particle size range of 0.5 to 350 μm by volume into 32 logarithmic divisions. The number of particles in each channel was then measured, and the median diameter at 50% of the volume of the measurement results was taken as the volume average particle size. The volume average particle size of the magnetic carrier in the first embodiment is 50 μm.

[0046] The non-magnetic toner is composed of at least a binder, a colorant, and a charge control agent. In the first embodiment, a styrene-acrylic resin is used as the binder resin, but styrene-based, polyester-based, polyethylene-based, and other resins can also be used. In the first embodiment, phthalocyanine blue is used as the colorant. However, other colorants may also be used, such as carbon black, chrome yellow, Hansa yellow, benzidine yellow, threne yellow, quinoline yellow, Permanent Orange GTR, pyrazolone orange, Vulcan orange, and Watch Young Red. Alternatively, other colorants may also be used, such as permanent red, brilliant amine 3B, brilliant amine 6B, Dipon oil red, pyrazolone red, lithol red, rhodamine B lake, lake red C, and rose bengal. Alternatively, other colorants may also be used, such as aniline blue, ultramarine blue, chalcoeol blue, methylene blue chloride, phthalocyanine green, and malachite green oxalate. Furthermore, the colorants such as the various pigments and dyes listed above may be used alone or in combination of two or more types.

[0047] The charge control agent may contain a reinforcing charge control agent as needed. Any known reinforcing charge control agent can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, and rhodamine dyes. Other examples include alkoxyamines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus simple substance or compounds, tungsten simple substance or compounds, fluorine-based surfactants, metal salicylate salts, and metal salts of salicylic acid derivatives.

[0048] The non-magnetic toner may also contain wax or external additives. Wax is contained to improve fixability and release from the fixing member during fixing. Examples of wax that can be used include paraffin wax, carnauba wax, and polyolefin, which are kneaded and dispersed in a binder resin. In the first embodiment, a resin in which a binder, a colorant, a charge control agent, and wax are kneaded and dispersed is used, which is pulverized by a mechanical pulverizer.

[0049] Examples of external additive particles include amorphous silica that has been hydrophobically treated, or inorganic oxide particles such as titanium oxide or titanium compounds. Adding these particles to the toner matrix is ​​advantageous for controlling the powder fluidity and charge of the toner. The particle size of the external additive particles is preferably approximately 1 nm to 100 nm. In the first embodiment, 0.5 wt% of titanium oxide with an average particle size of 50 nm, 0.5 wt% and 1.0 wt% of amorphous silica with average particle sizes of 2 nm and 100 nm were externally added.

[0050] The particle size of the toner having the above-described configuration was measured using a powder particle size image analyzer FPIA-3000 (manufactured by Sysmex Corporation), and the volume average particle size of the toner in the first embodiment was 6.0 μm. The cohesion degree of the toner having the above-described configuration was measured using a powder tester (manufactured by Hosokawa Micron Corporation), and the cohesion degree of the toner in the first embodiment was 30.

[0051] In the first embodiment, the external additive coverage of the toner is calculated from the atomic weight of silica-derived silicon (hereinafter abbreviated as Si) present on the surface of the toner particles, as measured by ESCA (X-ray photoelectron spectroscopy). ESCA is an analytical method that detects atoms within a depth range of a few nanometers or less from the surface of a sample. Therefore, it is possible to detect atoms on the surface of the toner. A 75 mm square platen (equipped with a screw hole with a diameter of approximately 1 mm for fixing the sample) attached to the device was used as the sample holder. The screw hole in the platen is a through hole, so the hole is plugged with resin or the like to create a recess with a depth of approximately 0.5 mm for powder measurement. The sample was prepared by packing the measurement sample into the recess with a spatula or the like and leveling it off.

[0052] The ESCA equipment and measurement conditions are as follows: Equipment used: PHI5000VersaProbeII (ULVAC-PHI) Analysis method: Narrow analysis Measurement conditions: X-ray source: Al-Kα X-ray conditions: 100μ25W15kV Photoelectron capture angle: 45 Pass Energy: 58.70 eV Measurement range: 300 μm x 200 μm Measurements were performed under the above conditions. The analysis method involves first correcting the peak derived from the C-C bond of the carbon 1s orbital to 285 eV. Then, the amount of Si derived from silica relative to the total amount of constituent elements is calculated from the peak area derived from the silicon 2p orbital, whose peak top is detected between 100 eV and 105 eV, using a relative sensitivity factor provided by ULVAC-PHI. Next, the silica alone applied to the toner is measured in the same manner as above, and the amount of Si derived from silica relative to the total amount of constituent elements is calculated. The ratio of the amount of Si when measuring the toner relative to the amount of Si when measuring the external additive alone is defined as the silica coverage in this invention.

[0053] When the coverage rate of the external additives on the toner was measured using ESCA (X-ray photoelectron spectroscopy), the coverage rate of the external additives on the toner in the first embodiment was 50%.

[0054] In the first embodiment, 200 g of developer D, which is a mixture of the above-mentioned toner and carrier at a mixture ratio (toner concentration) of 10 wt %, is charged into the developing device 4.

[0055] (Configuration of toner supply device) Next, the toner supply means (supply device 9) in the first embodiment will be described with reference to FIG.

[0056] The supply device 9 supplies the supply developer (toner) to the supply port 47 of the developing device 4 via the developer supply path 48. The developer supply container 91 contains the supply developer (toner) and is provided replaceably in the image forming apparatus 100.

[0057] A developer supply container memory 90 is provided as a memory unit (non-volatile memory) for each color in the developer supply container 91. The memory unit can be an IC chip, a barcode, or the like, and is preferably one that can be automatically read by an information reading means on the main body of the image forming apparatus 100.

[0058] In the first embodiment, the developer supply container memory 90 is provided in front of the developer supply container 91, and data can be read and written from the control unit 20 of the image forming apparatus 100. The image forming apparatus 100 is provided with an information reading means (not shown) for reading information stored in the developer supply container memory 90, and is configured to be able to communicate with the developer supply container memory 90 when the developer supply container 91 is attached to the image forming apparatus 100.

[0059] The developer supply container memory 90 stores unique information that differs for each individual developer supply container 91. Examples of the unique information include the manufacturing date, manufacturing lot, and characteristics of external additives of the supply developer (toner) contained in the developer supply container 91.

[0060] In the first embodiment, the information stored in the developer supply container memory 90 includes at least the external additive coverage rate at the time of toner production. When the developer supply container 91 is attached to the image forming apparatus 100, the control unit 20 reads the information stored in the developer supply container memory 90 (information relating to the external additive coverage rate at the time of toner production) using an information reading means. Then, the control unit 20 corrects the life expectancy prediction of the photosensitive unit 110 based on the read external additive coverage rate. This will be described in detail below.

[0061] (Photosensitive unit configuration) Next, the photosensitive unit 110 will be described in detail with reference to Fig. 4. Fig. 4 is a cross-sectional view showing the configuration of the photosensitive unit 110 according to the first embodiment.

[0062] 4, the photosensitive unit 110 collectively integrates the photosensitive drum 1, charging roller 2, and drum cleaner 6 (cleaning device). The photosensitive unit 110 is detachable from a predetermined position in the image forming units Sa to Sd. The photosensitive unit 110 is provided with a drum memory as a memory unit (non-volatile memory) for each color, similar to the developer supply container 91.

[0063] (Image forming device control system) Next, a detailed description will be given of the control system of the image forming apparatus 100. Fig. 5 is a block diagram showing a part of the control system of the image forming apparatus 100 according to the first embodiment.

[0064] As shown in FIG. 5, the control unit 20 (CPU) of the image forming apparatus 100 is connected to an accumulator 210, a communication unit 220, a calculation unit 230, a display unit 240 (display means), a drum memory 25, and a developer supply container memory 90.

[0065] In the first embodiment, the image forming apparatus 100 includes a means for detecting a distance obtained by accumulating the driving distance over which the photosensitive drum 1 has been driven to rotate (hereinafter referred to as the accumulated driving distance Lt of the photosensitive drum 1). The control unit 20 can store the driving distance over which the photosensitive drum 1 has been driven to rotate in the drum memory 25 via the accumulating unit 210. The control unit 20 can also display various types of information on the display unit 240, such as information relating to the life of the photosensitive unit 110 (for example, a notification urging the user to replace the photosensitive unit 110).

[0066] (Method for detecting the life of a photoconductor unit) In the first embodiment, the coverage of external additives on toner is measured in advance for each production lot of toner at the manufacturing stage of the replenishment developer (toner) to be filled into the developer supply container 91. Then, when the toner is filled into the developer supply container 91, information on the coverage of external additives on toner contained in the developer supply container 91 is stored in the developer supply container memory 90. In this way, the coverage of external additives on toner is measured for each production lot of toner, and therefore the same value of the external additive coverage is stored in the developer supply container memory 90 filled with toner from the same production lot.

[0067] Here, a description will be given of a method for detecting the end of life of the photosensitive unit 110 according to the first embodiment. In the first embodiment, the end of life of the photosensitive unit 110 is detected by predicting the amount of wear of the photosensitive drum 1.

[0068] Conventionally, the lifespan of the photosensitive unit 110 has been detected by predicting the driving distance of the photosensitive drum 1, the charging distance over which high voltage is applied to the charging roller 2, and the number of images formed on the transfer material P (number of prints).

[0069] For example, suppose the lifespan of the photosensitive unit 110 is set to 150,000 prints on A4 paper. In this case, the cumulative drive distance L of the photosensitive drum 1 corresponding to 300,000 prints is set to L150k, and the lifespan of the photosensitive drum 1 (lifespan of the photosensitive unit 110) is detected when the cumulative drive distance L of the photosensitive drum 1 reaches L150k. That is, the life (LF) value indicating the lifespan of the photosensitive unit 110 is defined by the following formula 1, and when LF=100[%] is reached, a warning regarding the lifespan of the photosensitive unit 110 is displayed on the display unit 240. LF=100×L / L150k[%] (1) On the other hand, one of the causes of the lifespan of the photosensitive drum 1 (lifespan of the photosensitive unit 110) is the amount of external additive that reaches the cleaning blade 61 via the photosensitive drum 1. Specifically, the greater the amount of external additive that reaches the cleaning blade 6 via the photosensitive drum 1, the stronger the sliding force of the cleaning blade 6 at the portion where the cleaning blade 6 contacts the photosensitive drum 1 tends to be. Therefore, the greater the amount of external additive that reaches the cleaning blade 6 via the photosensitive drum 1, the more wear on the photosensitive drum 1 progresses, and there is a risk that the lifespan of the photosensitive drum 1 (lifespan of the photosensitive unit 110) will be shortened. On the other hand, if the amount of external additive that reaches the cleaning blade 6 via the photosensitive drum 1 is small, the wear on the photosensitive drum 1 will progress more slowly, and therefore it is possible to prevent the lifespan of the photosensitive drum 1 (lifespan of the photosensitive unit 110) from being shortened.

[0070] The influence (coefficient) indicating the degree to which the external additive coverage rate for the toner affects the wear of the photosensitive drum 1 has been obtained in advance through experiments, and has the relationship shown in Table 1.

[0071] [Table 1]

[0072] More specifically, the wear amount prediction coefficient αL is determined from the relationship between the external additive coverage rate stored in the developer supply container memory 90, the external additive coverage rate determined by experiment and stored in advance in the memory unit of the image forming apparatus 100, and the wear amount of the photosensitive drum 1.

[0073] In the first embodiment, the life of the photosensitive drum 1 (life of the photosensitive unit 110) is detected in consideration of the fact that the life of the photosensitive drum 1 is determined by the supply of external additives to the cleaning blade 61. Specifically, in the first embodiment, the life of the photosensitive drum 1 (life of the photosensitive unit 110) is calculated based on usage information that numerically represents the usage status of the photosensitive drum 1 and a wear amount prediction coefficient αL.

[0074] More specifically, the life (LF) value indicating the life of the photosensitive unit 110 is calculated by the following formula 2. LF=100×Lt / L150k[%] (2) Here, the cumulative driving distance Lt of the photosensitive drum 1 is expressed by the following equation 3. Lt=αL1×L1+αL2×L2+···αLn×Ln···(3) Let αL1 be the wear amount prediction coefficient of the photosensitive drum 1 when a certain developer supply container 91a-1 is attached to the image forming apparatus 100, and L1 be the driving distance of the photosensitive drum 1 when the image forming apparatus 100 operates with the developer supply container 91a-1 attached to it. Let αL2 be the wear amount prediction coefficient of the photosensitive drum 1 when the developer supply container 91a-1 is subsequently replaced with a developer supply container 91a-2, and L2 be the driving distance of the photosensitive drum 1 when the image forming apparatus 100 operates with the developer supply container 91a-2 attached to it. Let αLn be the wear amount prediction coefficient of the photosensitive drum 1 when the developer supply container 91a-n is subsequently replaced with a developer supply container 91a-n, and Ln be the driving distance of the photosensitive drum 1 when the image forming apparatus 100 operates with the developer supply container 91a-n attached to it. The integrated driving distance Lt of the photosensitive drum 1 indicates the sum of the above-mentioned L1, L2, . . . , Ln. The integrated driving distance Lt of the photosensitive drum 1 is calculated by the integrating unit 210 and the calculating unit 230.

[0075] Here, a flowchart for explaining the control in the first embodiment (a series of processes related to calculation of the cumulative driving distance Lt of the photosensitive drum 1) is shown in Fig. 6. The control in Fig. 6 is executed by the control unit 20 reading out a control program stored in a storage unit of the image forming apparatus 100 and controlling various devices. The control in Fig. 6 starts after it is detected that a developer supply container 91 has been attached to the image forming apparatus 100.

[0076] After the developer supply container 91 is installed in the image forming apparatus 100, the control unit 20 reads information stored in the developer supply container memory 90 (S101) and acquires toner production lot information (S102). Then, the control unit 20 acquires information regarding the coverage rate of the external additives on the toner from the toner production lot information (S102). Next, the control unit 20 calculates the cumulative driving distance Lt of the photosensitive drum 1 using the external additive coverage rate acquired in S102 and Equation 3, stores it in the drum memory 25 (S103), and then ends the series of processes shown in FIG.

[0077] Next, a flowchart for explaining the control according to the first embodiment (a series of processes related to detecting the lifespan of the photosensitive unit 110) is shown in FIG. 7. The control in FIG. 7 is executed by the control unit 20 reading out a control program stored in the storage unit of the image forming apparatus 100 and controlling various devices. The control in FIG. 7 starts after the image forming operation is completed.

[0078] The control unit 20 reads the cumulative driving distance Lt of the photosensitive drum 1 calculated in S103 of Fig. 6 and stored in the drum memory 25 (S201). Then, the control unit 20 calculates a life (LF) value indicating the life of the photosensitive unit 110, and then stores the life (LF) value in the drum memory 25 (S202).

[0079] Next, the control unit 20 determines whether the LF value stored in the drum memory 25 is equal to or greater than a life threshold value preset in the drum memory 25 (S203). In the first embodiment, the life threshold value is set to 100%, so in S203, it is determined whether the LF value is less than 100%.

[0080] 7 is terminated and the state shifts to a normal image formation standby state. On the other hand, if the LF value reaches 100% (S203: NO), information regarding the life of the photosensitive unit 110 (specifically, information indicating that the life of the photosensitive unit 110 is nearing the end, a notification urging the replacement of the photosensitive unit 110, etc.) is displayed on the display unit 240 (S204).

[0081] In the first embodiment, when the LF value reaches 100%, for example, a notification urging replacement of the photosensitive unit 110 is displayed on the display unit 240, but this is not limiting. For example, a modified example may be one in which the LF value triggers automatic delivery of a replacement developer supply container 91, or the life (LF) value indicating the life of the photosensitive unit 110 is constantly displayed on the display unit 240 using various display methods such as a percentage display or a memory display.

[0082] In the first embodiment, an example has been described in which the lifespan of the photosensitive unit 110 is detected using the cumulative driving distance Lt of the photosensitive drum 1 as usage information that numerically represents the usage status of the photosensitive drum 1, but this is not limiting. For example, a modified example may be configured to use the cumulative number of rotations of the photosensitive drum 1 as usage information.

[0083] In the first embodiment described above, the control unit 20 reads the information (information related to the external additive coverage rate at the time of toner production) stored in the developer supply container memory 90 when the developer supply container 91 is attached to the image forming apparatus 100. Then, the control unit 20 corrects the life expectancy of the photosensitive unit 110 based on the read external additive coverage rate.

[0084] A specific description will be given below. A first case is when the coverage rate of the external additive to the toner stored in the developer supply container memory 90 is a first ratio and the cumulative driving distance of the photosensitive drum 1 is a predetermined distance. A second case is when the coverage rate of the external additive to the toner stored in the developer supply container memory 90 is a second ratio that is higher than the first ratio and the cumulative driving distance of the photosensitive drum 1 is a predetermined distance. In the first embodiment, information regarding replacement of the photosensitive unit 110 is displayed on the display unit 240 at an earlier timing in the second case than in the first case.

[0085] According to the first embodiment, the life of the photosensitive drum 1 (life of the photosensitive unit 110) can be detected taking into account the amount of external additive carried by the toner matrix, so that replacement of the photosensitive unit 110 can be promoted at an appropriate time.

[0086] [Second embodiment] The configuration of the image forming apparatus 100 in the second embodiment is the same as that in the first embodiment described above, and therefore detailed description thereof will be omitted. In the first embodiment described above, the life of the photosensitive unit 110 is calculated by predicting wear of the photosensitive drum 1. In contrast, the second embodiment differs from the first embodiment in that the life of the photosensitive unit 110 is calculated by predicting contamination of the charging roller 2.

[0087] In the second embodiment, the image forming apparatus 100 includes a means for detecting a distance obtained by accumulating the driving distance of the charging roller 2 that has been rotationally driven (hereinafter referred to as the accumulated driving distance Dt of the charging roller 2). The control unit 20 can store the accumulated driving distance Dt of the charging roller 2 in the drum memory 25 via the accumulating unit 210. The control unit 20 can also display various information on the display unit 240, such as information related to the life of the photosensitive unit 110 (for example, a notification urging the user to replace the photosensitive unit 110).

[0088] A method for detecting the lifespan of the photosensitive unit 110 according to the second embodiment will be described below. In the second embodiment, the lifespan of the photosensitive unit 110 is detected by predicting contamination of the charging roller 2.

[0089] Conventionally, the lifespan of the photosensitive unit 110 has been detected by predicting the driving distance over which the charging roller 2 is rotated, the charging distance over which high voltage is applied to the charging roller 2, and the number of images formed on the transfer material P (number of prints).

[0090] For example, suppose the life of the charging roller 2 is set to 150,000 prints on A4 paper. In this case, the charging distance D corresponding to 300,000 prints is set to D150k, and the life of the charging roller 2 (life of the photoconductor unit 110) is detected when the cumulative charging distance D reaches D150k. That is, the life (LF) value indicating the life of the photoconductor unit 110 is defined by the following equation 3, and when LF reaches 100[%], a warning regarding the life of the photoconductor unit 110 is displayed on the display unit 240. LF=100×D / D150k[%] (4) On the other hand, one of the causes of the lifespan of the charging roller 2 (lifespan of the photosensitive unit 110) is the amount of external additive that reaches the charging roller 2 via the photosensitive drum 1. Specifically, the greater the amount of external additive that reaches the charging roller 2 via the photosensitive drum 1, the more contamination of the charging roller 2 progresses in the area where the charging roller 2 is close to the photosensitive drum 1, which may shorten the lifespan of the charging roller 2 (lifespan of the photosensitive unit 110). On the other hand, the smaller the amount of external additive that reaches the charging roller 2 via the photosensitive drum 1, the more slowly the contamination of the charging roller 2 progresses, which may prevent the lifespan of the charging roller 2 (lifespan of the photosensitive unit 110) from being shortened.

[0091] The influence (coefficient) indicating the degree to which the external additive coverage rate on the toner affects the contamination of the charging roller 2 has been obtained in advance through experiments, and has the relationship shown in Table 2.

[0092] [Table 2]

[0093] More specifically, the contamination amount prediction coefficient αD is determined from the relationship between the external additive coverage rate stored in the developer supply container memory 90, the external additive coverage rate determined by experiment and stored in advance in the memory unit of the image forming apparatus 100, and the contamination amount of the charging roller 2.

[0094] In the second embodiment, the life of the charging roller 2 (life of the photosensitive unit 110) is detected taking into consideration that the life of the charging roller 2 is determined by the amount of external additive that reaches the charging roller 2 via the photosensitive drum 1. Specifically, in the second embodiment, the life of the charging roller 2 (life of the photosensitive unit 110) is calculated based on usage information that numerically represents the usage status of the charging roller 2 and a contamination amount prediction coefficient.

[0095] Specifically, the life (LF) value indicating the life of the photosensitive unit 110 is calculated by the following equation 4. LF=100×Dt / D150k[%] (5) Here, the cumulative driving distance Dt of the charging roller 2 is expressed by the following equation 6. Dt=αD1×D1+αD2×D2+···αDn×Dn···(6) The contamination amount prediction coefficient of the charge roller 2 when a certain developer supply container 91a-1 is attached to the image forming apparatus 100 is set to αD1, and the driving distance of the charge roller 2 when the image forming apparatus 100 operates with the developer supply container 91a-1 attached is set to D1. The contamination amount prediction coefficient of the charge roller 2 when the developer supply container 91a-1 is subsequently replaced with a developer supply container 91a-2 is set to αD2, and the driving distance of the charge roller 2 when the image forming apparatus 100 operates with the developer supply container 91a-2 attached is set to D2. Further, the contamination amount prediction coefficient of the charge roller 2 when the developer supply container 91a-n is subsequently replaced with a developer supply container 91a-n is set to αDn, and the driving distance of the charge roller 2 when the image forming apparatus 100 operates with the developer supply container 91a-n attached is set to Dn. The cumulative driving distance Dt of the charging roller 2 is the sum of the above-mentioned D1, D2, . . . , Dn. The cumulative driving distance Dt of the charging roller 2 is calculated by the accumulator 210 and the calculator 230.

[0096] Here, a flowchart for explaining the control in the second embodiment (a series of processes related to calculation of the cumulative driving distance Dt of the charging roller 2) is shown in Fig. 8. The control in Fig. 8 is executed by the control unit 20 reading out a control program stored in a storage unit of the image forming apparatus 100 and controlling various devices. The control in Fig. 8 starts after it is detected that the developer supply container 91 has been attached to the image forming apparatus 100.

[0097] After the developer supply container 91 is installed in the image forming apparatus 100, the control unit 20 reads information stored in the developer supply container memory 90 (S301) and acquires toner production lot information (S302). Then, the control unit 20 acquires information regarding the coverage rate of the external additive with respect to the toner from the toner production lot information (S302). Next, the control unit 20 calculates the cumulative driving distance Dt of the charging roller 2 using the external additive coverage rate acquired in S302 and Equation 6, stores it in the drum memory 25 (S303), and then ends the series of processes shown in FIG.

[0098] Next, a flowchart for explaining the control according to the second embodiment (a series of processes related to detecting the life of the photosensitive unit 110) is shown in Fig. 9. The control in Fig. 9 is executed by the control unit 20 reading out a control program stored in the storage unit of the image forming apparatus 100 and controlling various devices. The control in Fig. 9 starts after the image forming operation is completed.

[0099] The control unit 20 reads the cumulative driving distance Dt of the charging roller 2 calculated in S303 of Fig. 8 and stored in the drum memory 25 (S401). Then, the control unit 20 calculates a life (LF) value indicating the life of the photosensitive unit 110, and then stores the life (LF) value in the drum memory 25 (S402).

[0100] Next, the control unit 20 determines whether the LF value stored in the drum memory 25 is equal to or greater than a life threshold value preset in the drum memory 25 (S403). In the second embodiment, the life threshold value is set to 100%, so in S403 it is determined whether the LF value is less than 100%.

[0101] 9 is terminated and the state shifts to a normal image formation standby state. On the other hand, if the LF value reaches 100% (S403: NO), information regarding the life of the photosensitive unit 110 (specifically, information indicating that the life of the photosensitive unit 110 is nearing the end, a notification urging the replacement of the photosensitive unit 110, etc.) is displayed on the display unit 240 (S404).

[0102] In the second embodiment, when the LF value reaches 100%, for example, a notification urging replacement of the photosensitive unit 110 is displayed on the display unit 240, but this is not limiting. For example, a modified example may be one in which the LF value triggers automatic delivery of a replacement developer supply container 91, or the life (LF) value indicating the life of the photosensitive unit 110 is constantly displayed on the display unit 240 using various display methods such as a percentage display or a memory display.

[0103] In the second embodiment, an example has been described in which the lifespan of the photosensitive unit 110 is detected using the cumulative driving distance Dt of the charging roller 2 as usage information that numerically represents the usage status of the charging roller 2, but this is not limiting. For example, a modified example may be configured to use the cumulative number of rotations of the charging roller 2 as usage information.

[0104] In the second embodiment described above, the control unit 20 reads the information (information related to the external additive coverage rate at the time of toner production) stored in the developer supply container memory 90 when the developer supply container 91 is attached to the image forming apparatus 100. Then, the control unit 20 corrects the life expectancy of the photosensitive unit 110 based on the read external additive coverage rate.

[0105] A specific description will be given below. A first case is when the coverage rate of the external additive to the toner stored in the developer supply container memory 90 is a first ratio and the cumulative driving distance of the charging roller 2 is a predetermined distance. A second case is when the coverage rate of the external additive to the toner stored in the developer supply container memory 90 is a second ratio that is higher than the first ratio and the cumulative driving distance of the charging roller 2 is a predetermined distance. In the second embodiment, information regarding replacement of the photosensitive unit 110 is displayed on the display unit 240 at an earlier timing in the second case than in the first case.

[0106] According to the second embodiment, the life of the charging roller 2 (life of the photosensitive unit 110) can be detected taking into account the amount of external additive carried by the toner base material, so that replacement of the photosensitive unit 110 can be promoted at an appropriate time.

[0107] [Other embodiments] The present invention is not limited to the above-described embodiments, and various modifications (including organic combinations of the respective embodiments) are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0108] In the above embodiment, the image forming apparatus 100 is described as using the intermediate transfer belt 51 as shown in Fig. 1, but the present invention is not limited to this. The present invention can also be applied to an image forming apparatus configured to transfer the image by directly contacting the transfer material P with the photosensitive drum 1 in sequence. [Explanation of symbols]

[0109] 1 Photosensitive drum 2 Charging roller 4. Developing device 20 Control Unit 90 Developer supply container memory 91 Developer supply container 100 Image forming device 110 Photoconductor unit 240 Display section

Claims

1. a photoreceptor unit including a photoreceptor on which an electrostatic latent image is formed and a charging member for charging the photoreceptor; a developing device that develops the electrostatic latent image formed on the photosensitive member using a developer containing toner and a carrier; a supply container for accommodating a supply developer to be supplied to the developing device; a storage unit provided in the supply container and storing information regarding a coverage rate of an external additive to the toner of the supply developer contained in the supply container; A display unit; a control unit that controls the display unit to display information regarding replacement of the photosensitive unit based on the information regarding the coverage stored in the storage unit; An image forming apparatus comprising:

2. The control unit controls the display unit to display information regarding replacement of the photosensitive unit based on the information regarding the coverage rate and the information regarding the driving distance of the photosensitive member stored in the storage unit.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. The control unit controls the display unit to display information regarding replacement of the photosensitive unit at an earlier timing when the coverage stored in the storage unit is a second ratio higher than the first ratio and the accumulated driving distance of the photosensitive body is the predetermined distance than when the coverage stored in the storage unit is a first ratio and the accumulated driving distance of the photosensitive body is the predetermined distance.

3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

4. The control unit controls the display unit to display information regarding replacement of the photosensitive unit based on information regarding the coverage rate and information regarding the driving distance of the charging member stored in the storage unit.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

5. The control unit controls the display unit to display information regarding replacement of the photosensitive unit at an earlier timing when the coverage stored in the storage unit is a second ratio higher than the first ratio and the cumulative driving distance of the charging member is the predetermined distance than when the coverage stored in the storage unit is a first ratio and the cumulative driving distance of the charging member is the predetermined distance.

5. The image forming apparatus according to claim 4.

Images