Image forming apparatus

Abstract

This invention provides an image forming apparatus that can accurately determine the lifespan of a reused developing unit. [Solution] When it is detected that the replaced developing unit is a reused item (YES in S2), the deterioration estimation mode is performed. When the deterioration estimation mode is performed, a background stain detection image and a white spot detection image are formed on a predetermined sheet of paper as deterioration state detection images to understand the deterioration state of the replaced reused developing unit (S13, S14). The background stain detection image and white spot detection image formed on the predetermined sheet of paper are read by an inline sensor, and the deterioration state of the replaced reused developing unit is estimated based on the read background stain detection image and white spot detection image (S15, S16). Then, the remaining lifespan of the replaced reused developing unit is set based on the estimated deterioration state.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus.

Background Art

[0002] Conventionally, an image forming apparatus is known that includes a developing unit that is detachably configured on a device main body and develops a latent image on a latent image carrier, and a control unit that determines the life of the developing unit.

[0003] Patent Document 1 describes a method for determining the life of an image unit including a developing unit detachably configured on a device main body and a photoreceptor as follows. That is, the driving time of the developing roller is stored in the memory of the device main body. When the driving time of the developing roller stored in the memory of the device main body exceeds a threshold value, it is determined that the life of the image unit has expired. Further, in Patent Document 1, when it is detected that the image unit has been replaced, it is confirmed whether there is new product information in the memory provided in the image unit. When it is determined that there is no new product information and the image unit is an old product, it is confirmed whether the driving time of the developing roller stored in the memory of the image unit is greater than the driving time of the developing roller stored in the memory of the device main body. And when the driving time of the developing roller stored in the memory of the image unit is greater than the driving time of the developing roller stored in the memory of the device main body, it is described that the driving time of the developing roller stored in the memory of the device main body is updated to the driving time of the developing roller stored in the memory of the image unit.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, due to variations in the previous usage environment and other factors, the rate of deterioration of reused development units varied, making it difficult to accurately estimate the lifespan of the development unit based on the operating time of the development rollers stored in the image unit's memory. This resulted in poor accuracy in determining the lifespan of reused development units. [Means for solving the problem]

[0005] To solve the above-mentioned problems, the present invention provides an image forming apparatus comprising a developing unit detachably configured to be attached to the main body of the apparatus for developing a latent image on a latent image carrier, and a control unit for determining the lifespan of the developing unit, wherein the control unit detects whether the replaced developing unit is a reused item, and when it is detected that the replaced developing unit is a reused item, it forms a deterioration state detection image for understanding the deterioration state of the replaced reused developing unit, and sets the remaining lifespan of the replaced reused developing unit based on the formed deterioration state detection image. [Effects of the Invention]

[0006] According to the present invention, the lifespan of a reusable developing unit can be determined with high accuracy. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic front view of the overall configuration of a color copier according to this embodiment. [Figure 2] A schematic diagram showing the general configuration of one of the four image-making sections. [Figure 3] A diagram showing the developing unit and photosensitive drum in the longitudinal direction. [Figure 4] This is a functional block diagram of the color copier. [Figure 5] A functional block diagram showing an example of a toner concentration sensor. [Figure 6] This diagram shows an example of a detection circuit board for detecting "new," "reused," and "installed" items. [Figure 7] Flowchart of the initial replacement process. [Figure 8] A diagram showing an example of the relationship between development potential and toner adhesion amount. [Figure 9] (a) is a graph showing the relationship between background staining and the number of printed pages, and (b) is a graph showing the relationship between toner dispersion and accumulation and the number of printed pages. [Figure 10] A graph showing the relationship between the number of white spots in the image caused by carrier adhesion and the number of printed sheets. [Figure 11] Flowchart of the degradation state estimation mode. [Figure 12] A graph showing the relationship between soil stain density and soil potential. [Figure 13] A graph showing the relationship between the number of white spots, the development potential, and the primary transfer current. [Figure 14] A graph showing an example of the relationship between the image density of the calculated soil contamination detection image and the remaining lifespan. [Figure 15] (a) is a figure showing the image of white spots detected on the specified paper, and (b) is a figure showing the image data after image processing of the read white spot detection image. [Figure 16] A graph showing the relationship between the number of white spots detected and the remaining lifespan (%). [Figure 17] Flowchart of the mode for estimating the degradation state of modified cases. [Figure 18] A diagram showing an example of a home screen. [Figure 19] This diagram shows an example of the settings screen when replacing the developing unit. [Figure 20] A diagram showing an example of an image density rank input screen. [Figure 21] This figure shows an example of the white spot rank input screen. [Figure 22] A diagram illustrating the determination of remaining lifespan based on image density rank. [Figure 23] A diagram illustrating the determination of remaining lifespan based on the white spot rank. [Figure 24] This diagram shows an example of a warning message that asks whether or not to modify the selected rank. [Modes for carrying out the invention]

[0008] The best mode for carrying out the present invention will be described below based on the drawings. It should be noted that a person skilled in the art can easily make changes and modifications to the present invention within the scope of the claims to form other embodiments, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode in this invention and does not limit the scope of the claims.

[0009] FIG. 1 is a schematic front view showing a perspective view of the overall configuration of a color copier as an example of an image forming apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an in-body paper discharge type color copier that uses an electrophotographic method exemplified as an image forming apparatus according to an embodiment of the present invention. In the figure, the Z direction is the vertical direction, the Y direction in the figure is the front-rear direction (also the axial direction) of the apparatus, and the X direction in the figure indicates the left-right direction of the apparatus.

[0010] This color copier 1 includes a schematic box-shaped apparatus main body 10 that is the housing of the entire image forming apparatus, and an image reading unit 2 that is disposed above the apparatus main body 10 and reads an image of a document. Further, the color copier 1 has an image forming unit 3 that is disposed inside the apparatus main body and records and forms an image on a sheet of paper (hereinafter referred to as "paper" for the sake of simplicity, which means a sheet-like recording medium including copy paper, resin sheets for OHP, thick paper, postcards, etc.) based on image information read by the image reading unit 2 or transmitted from an external device such as a personal computer.

[0011] Further, it has a paper discharge space 12 as a discharge space for discharging the paper on which an image is recorded between the image reading unit 2 and the image forming unit 3. Also, at the lowermost part of the apparatus main body 10, a paper feeding device for supplying a sheet (which means a sheet-like recording medium including copy paper, resin sheets for OHP, thick paper, postcards, etc., and will be hereinafter referred to as "paper" for the sake of simplicity) to a paper conveyance path as a sheet conveyance path is disposed. Further, above the image forming unit 3, a paper discharge unit for discharging the paper on which an image is recorded to the paper discharge space 12 is provided, and a paper conveyance path 6 is provided between the paper feeding device and the in-body paper discharge unit 5.

[0012] The image reading unit 2 has a contact glass 20 as a document platen on which the document is placed. It also has a light source 21 positioned directly below the contact glass 20 that moves and illuminates the document with light, an imaging lens 22 that forms an image of the reflected light from the document, and an image sensor 23 such as a CCD positioned at the imaging position to read the document image. Furthermore, the image reading unit 2 also has multiple mirrors that reflect the reflected light from the document and guide it to the imaging lens 22.

[0013] Furthermore, a pressure plate 24 is provided at the top of the image reading unit 2 to hold down the document placed on the contact glass 20. Alternatively, an automatic document feeder (ADF) that automatically feeds the document onto the contact glass 20 may be installed instead of this pressure plate 24.

[0014] The image forming unit 3 is equipped with four image-forming units 11Y, 11C, 11M, and 11K, corresponding to a total of four toner colors: yellow, cyan, magenta (the three primary colors of pigments), and black. Below these four image-forming units 11Y, 11C, 11M, and 11K, the image forming unit 34 is provided for writing latent images to each of the photosensitive drums, which will be described later. The image forming unit 3 is also equipped with four toner bottles 31Y, 31C, 31M, and 31K, which contain new toners of the colors corresponding to each image-forming unit 11Y, 11C, 11M, and 11K. In addition, it is equipped with a transfer unit 32 for transferring the toner images formed in each image-forming unit 11Y, 11C, 11M, and 11K to paper, and a fixing unit 33 for fixing the toner images to the paper.

[0015] The image-forming units 11Y, 11C, 11M, and 11K are arranged in the order of yellow, cyan, magenta, and black from upstream to downstream along the direction of movement of the outer surface of the intermediate transfer belt 32a, which is an intermediate transfer body described later (arrow Xa in the figure). Each image-forming unit 11Y, 11C, 11M, and 11K has a photoreceptor drum 7Y, 7C, 7M, and 7K, which are latent image carriers that rotate clockwise when viewed from the front. In addition, the unit has a charging member as a charging means, a developing unit 30Y, 30C, 30M, and 30K, a cleaning device, and the like, centered around the photoreceptor drum.

[0016] The charging device charges the outer surface of each photoreceptor drum 7Y, 7C, 7M, and 7K uniformly. The developing units 30Y, 30C, 30M, and 30K visualize the electrostatic latent image formed on each photoreceptor drum 7Y, 7C, 7M, and 7K by the writing unit 34, which is an exposure means described later, as a monochromatic toner image using the corresponding toners. The cleaning device cleans and recovers the residual toner that remains on the outer surface of the photoreceptor drums 7Y, 7C, 7M, and 7K after transfer.

[0017] The writing unit 34 is equipped with a polygon mirror and an fθ lens. The writing unit 34 scans the image information input from the image reading unit 2, a personal computer, an external scanner, etc., while irradiating it with laser light from a laser light emitter. It then selectively exposes the outer surface of the uniformly charged photoreceptor drums 7Y, 7C, 7M, and 7K, lowering the surface potential of the irradiated area and forming an electrostatic latent image on the photoreceptor drum.

[0018] Toner bottles 31Y, 31C, 31M, and 31K are each individually filled with new toner of the four colors mentioned above. The toner of each color in toner bottles 31Y, 31C, 31M, and 31K is supplied to the developing units 30Y, 30C, 30M, and 30K of each image processing unit 11Y, 11C, 11M, and 11K via a transport path.

[0019] The transfer unit 32, which is the transfer means, has an intermediate transfer belt 32a, which is an endless belt made of a multilayer structure of elastic resin, as an intermediate transfer body. This intermediate transfer belt 32a is supported and tensioned (meaning stretched under tension, the same applies hereinafter) by a plurality of rollers. Specifically, it is supported and tensioned by four support rollers 32b, 32c, 32d, and 32e, four primary transfer rollers 32f, and a secondary transfer roller 32g.

[0020] The support roller 32b is a drive roller connected to a drive means and has the function of rotating the intermediate transfer belt 32a in the direction of arrow Xa in the figure. A secondary transfer roller 32g is positioned opposite the support roller 32b (hereinafter referred to as "drive roller 32b") across the intermediate transfer belt 32a (meaning to be positioned and installed, or to be installed at a predetermined position; the same applies hereinafter). Near the support roller 32c, a cleaning device 32h is provided to scrape off residual toner adhering to the outer surface of the intermediate transfer belt 32a.

[0021] Each primary transfer roller 32f is positioned slightly downstream in the transport direction of the intermediate transfer belt 32a from the direct contact position where the center-to-center distance is shortest, taking into consideration image degradation due to air gap discharge. Each primary transfer roller 32f functions as a contact-type transfer bias (transfer voltage) application means. Specifically, each primary transfer roller 32f is connected to a bias power supply and is configured to apply (meaning apply voltage to, hereafter the same) the primary transfer bias from the back surface (inner circumferential surface) of the intermediate transfer belt 32a.

[0022] The secondary transfer roller 32g is biased by a biasing means and pressed against the intermediate transfer belt 32a on the outer circumference of the drive roller 32b, so as to form a secondary transfer nip between it and the drive roller 32b. The drive roller 32b is a contact-type transfer bias application means connected to a bias power supply. Alternatively, the secondary transfer roller 32g may also be a transfer bias application means, in which case a transfer bias with opposite polarity to the toner image to be transferred is applied.

[0023] The fixing unit 33 includes a fixing belt 33c, which is an endless belt stretched between a fixing roller 33a and a heating roller 33b, and a pressure roller 33d as a pressurizing member. The pressure roller 33d is pressed against the fixing belt 33c (meaning it is in pressurized contact, the same applies hereinafter), forming a fixing nip between it and the fixing belt 33c. Heat and pressure are applied to the paper that has been transported through the paper transport path 6, which will be described later, in this fixing nip, and the toner image transferred in the secondary transfer nip of the transfer unit 32 melts and adheres to the paper, thereby fixing it.

[0024] The paper feeding device includes paper feed cassettes 40 and 41 that can be pulled out from the main unit 10 and store predetermined paper of different sizes as sheets, and paper feed rollers 42 and 43 that press the stored paper from above with a predetermined pressure. Based on the control signal of the control means, the paper feeding device uses the paper feed rollers 42 and 43 to feed the paper stored in the paper feed cassettes 40 and 41 to the paper transport path 6, which will be described later.

[0025] The paper feeder also includes a manual feed tray 44 for placing any paper within a predetermined size range that can be transported, and a paper feed roller 45 for feeding this paper. The paper feeder is configured to feed the paper placed in the manual feed tray 44 to the paper transport path 6, which will be described later, by rotating the paper feed roller 45.

[0026] The internal paper output section 5 has a paper output tray 5a formed on the device body 10 below the paper output space 12 between the aforementioned toner bottles 31Y, 31C, 31M, and 31K and the image reading section 2, with an inclined surface. The internal paper output section 5 also includes a pair of paper output rollers 5b that eject (discharge) the paper that has passed through the fuser unit 33 from the paper transport path 6, which will be described later. Thus, the color copier 1 of this embodiment is an internal paper output type paper output section that has the function of stacking the paper ejected by the paper output roller pair 5b onto the paper output tray 5a.

[0027] The paper transport path 6 has a normal transport path 6a that uses a vertical transport method (vertical pass method) to transport paper from the paper feed device located at the bottom of the main body 10 to the paper discharge section 5 located at the top of the main body 10. It also has a reverse transport path 6b that reverses the paper for double-sided printing. These transport paths can be switched by a switching claw 6c, which guides the paper to the reverse transport path 6b. The paper guided to the reverse transport path 6b is carried to the upper part 6e of the reverse transport path 6b by a pair of reverse transport rollers 6d, and then reversed in a switchback manner by the pair of reverse transport rollers 6d reversing. After that, it is transported to the normal transport path 6a in front of the pair of registration rollers 6f, which will be described later.

[0028] The normal transport path 6a and the reverse transport path 6b are equipped with multiple transport roller pairs at intervals corresponding to the minimum paper size, and the paper is transported by rotating while being gripped by these transport roller pairs. In addition, the normal transport path 6a is equipped with a registration roller pair 6f below the secondary transfer nip, and this registration roller pair 6f adjusts the timing of transporting the paper to the secondary transfer nip based on commands from the control means.

[0029] Furthermore, a waste toner container 18 is provided on the left side of the paper feed cassette 40 in the diagram. This container holds the waste toner removed by the cleaning devices of each image processing unit 11Y, 11C, 11M, and 11K, as well as the waste toner removed by the cleaning device 32h of the transfer unit 32.

[0030] Figure 2 is a schematic diagram showing the general configuration of one of the four image-making units 11, and Figure 3 is a diagram showing the developing unit 30 and the photoreceptor drum 7 in the longitudinal direction. Since the four image-forming units 11 have almost identical structures except for the color of the toner used, the letters (Y, M, C, K) in the symbols of the components such as the image-forming units 11 and the developing unit 30 are omitted from the diagram. The image-forming unit 11 consists of a photoreceptor drum 7 as a latent image carrier, a photoreceptor unit 60 equipped with a charging member 62, a cleaning device 61, a static elimination unit, etc., arranged around the photoreceptor drum 7, and a developing unit 30. The photoreceptor unit 60 and the developing unit 30 are each configured to be detachable from the main body 10 of the device. The image-forming unit 11 performs an image-forming process (charging process, exposure process, developing process, transfer process, cleaning process) on the photoreceptor drum 7 to form images of each color on the photoreceptor drum 7.

[0031] The photoreceptor drum 7 is driven to rotate clockwise in Figure 2 by a drive motor. A charging bias is applied to the charging member 62, uniformly charging the surface of the photoreceptor drum 7 (charging step). Subsequently, the surface of the photoreceptor drum 7 reaches the irradiation position of the laser light L emitted from the writing unit 34, which is the exposure means. At this position, the writing unit 34 forms an electrostatic latent image corresponding to each color by exposure scanning (exposure step). Subsequently, the surface of the photoreceptor drum 7 reaches the position opposite the developing unit 30. At this position, the developing unit 30 develops the electrostatic latent image and forms toner images of each color (development step). Subsequently, the surface of the photoreceptor drum 7 is in the primary transfer section, which faces the primary transfer roller 32f across the intermediate transfer belt 32a, and the toner image on the photoreceptor drum 7 is transferred onto the intermediate transfer belt 32a (primary transfer step). By transferring the toner images of each color formed on the photoreceptor drum 7 onto the intermediate transfer belt 32a, a color image is formed on the intermediate transfer belt 32a. Toner residue remaining on the outer surface of the photoreceptor drum 7 after transfer is removed by the cleaning brush roller 61b and cleaning blade 61a of the cleaning device 61.

[0032] Next, the configuration and operation of the developing unit 30 will be explained in more detail. The developing unit 30 comprises a developing case 58 and a base member 59 that rotatably holds the developing case 58. The developing case 58 houses a developing roller 51 facing the photoreceptor drum 7, a doctor blade 52 facing the developing roller 51, and two transport screws 55a and 55b arranged in the first developer storage section 53 and the second developer storage section 54. Furthermore, the developing case 58 is fitted with a toner concentration sensor 56 that detects the toner concentration in the developer in the first developer storage section 53.

[0033] The developing roller 51 is configured to form a developing area by facing the photoreceptor drum 7 with a small gap between them. The developing roller 51 includes a magnet 51b having multiple magnetic poles fixed inside, and a sleeve 51a that rotates around the magnet 51b. The developer storage sections (53, 54) contain a two-component developer consisting of a carrier and toner. The second developer storage section 54 has a toner supply port 57 formed above it.

[0034] The outer circumferential surface of the sleeve 51a of the developing roller 51 is provided with multiple V-grooves or multiple recesses created by sandblasting. The sleeve 51a is driven to rotate in the direction of the arrow in Figure 2 (counterclockwise). The developer supported on the developing roller 51 by the magnetic field formed by the magnet 51b moves along the developing roller 51 as the sleeve 51a rotates. The developer in the developing unit 30 is adjusted so that the proportion of toner in the developer (toner concentration) is within a predetermined range. In accordance with the toner consumption in the developing unit 30, the toner contained in the toner bottle 31 is supplied into the developing case 58 from the toner supply port 71a of the toner supply pipe 71 of the toner supply device via the toner supply port 57 provided in the toner supply section 58e.

[0035] The first developer storage section 53 and the second developer storage section 54 are separated by a partition member 58a, and the longitudinal ends of the two developer storage sections are in communication with each other via communication openings 58b and 58c. The first transport screw 55a supplies developer to the developing roller 51 while transporting the developer received from the second developer storage section 54 via the communication port 58b in the longitudinal direction, and also recovers the developer that has been detached from the developing roller 51 after the developing process. The second transport screw 55b agitates and mixes the developer that has been transported from the first developer storage section 53 via the communication port 58c and the fresh toner supplied from the toner supply port 57 in the longitudinal direction. In this way, the developer in the developing case 58 is mixed and agitated by the two transport screws 55a and 55b as it circulates through the two developer storage sections (53 and 54).

[0036] The fresh toner in the developer supplied from the toner supply port 57 is attracted to the carrier by triboelectric charging and is then supported on the developer roller 51 together with the carrier by the magnetic force formed on the roller 51. The developer supported on the developer roller 51 reaches the position of the doctor blade 52.

[0037] Then, the developer on the developing roller 51 is adjusted to the appropriate amount at this position and then transported to the developing area, which is opposite the photoreceptor drum 7. When a developing bias is applied to the sleeve, a developing electric field is formed between the sleeve and the photoreceptor drum 7 in the developing area. Due to this developing electric field, the toner in the developer on the surface of the sleeve is supplied to the latent image on the surface of the photoreceptor drum 7 in the developing area, and the latent image on the photoreceptor drum 7 is developed. After that, the developer remaining on the developing roller 51 reaches above the first developer storage section 53 as the sleeve rotates, and at this position it detaches from the developing roller 51.

[0038] The toner concentration detection result of the toner concentration sensor 56 is sent as an electrical signal to the CPU 80a (see Figure 4). The CPU 80a performs a comparison between the output voltage from the toner concentration sensor 56 and the target voltage value Vtref, which is a target value of the output voltage stored in the storage 81 (see Figure 4), which is the storage means of the main unit of the device, according to a predetermined control program stored in the ROM 80b and storage 81. Then, it drives the toner supply device to supply an appropriate amount of toner from the toner supply port 57 according to the comparison result, and the appropriate amount of toner is supplied from the toner bottle 31 to the developer in the second developer storage section 54 (toner supply control).

[0039] In this embodiment, the target voltage value Vtref of the toner density sensor 56 is changed based on the image area ratio over a predetermined period and the image density (toner adhesion amount) of the detection toner patch formed every predetermined number of sheets during continuous printing. The image density (toner adhesion amount) of this detection toner patch is detected by an optical sensor unit 63 positioned opposite the outer circumferential surface of the intermediate transfer belt 32a shown in Figure 1.

[0040] The developing case 58 has abutting portion 58d that abuts against a holding portion 7a that rotatably holds both sides of the photoreceptor drum 7. When this abutting portion 58d abuts against the holding portion 7a, the developing roller 51 is positioned in a developing position facing the photoreceptor drum 7 with a predetermined gap between them.

[0041] The base member 59 has a pair of faceplates 59a and 59b and a connecting portion 59c that connects these faceplates. The developing case 58 is rotatably supported by the pair of faceplates 59a and 59b of the base member 59. As the developing case 58 rotates, the developing roller 51 moves between a developing position shown in Figure 3, where it faces the photoreceptor drum 7 with a predetermined gap, and a retracted position, where it is retracted from the photoreceptor drum 7.

[0042] When attaching or detaching the developing unit 30 or the photoreceptor unit 60 to the main unit 10, the developing case 58 is rotated to move the developing roller 51 from the developing position to the retracted position. Specifically, the main body of the color copier 1 is equipped with a rotating mechanism for rotating the developing case 58. When attaching or detaching the developing unit 30 or the photoreceptor unit 60 to the main unit 10, the operator operates the rotating mechanism to rotate the developing case 58 and position the developing roller 51 in the retracted position. This makes it less likely for problems such as damage to the developing unit 30 or the photoreceptor unit 60 due to interference to occur when attaching or detaching them to the main unit 10.

[0043] Figure 4 is a functional block diagram of this color copier 1. The control unit 80 includes a CPU 80a, ROM 80b, RAM 80c, printer control unit 82, image reading control unit 83, operation panel control unit 84, life setting control unit 85, etc., and these parts are connected by a bus.

[0044] The CPU 80a starts the OS using a boot program stored in the ROM 80b. Then, the CPU 80a controls the entire color copier by executing control programs stored in the storage 81 and ROM 80b on top of the OS. For example, the CPU 80a executes a predetermined control program to perform the toner replenishment control and image density adjustment control described above.

[0045] RAM 80c is used as the main memory and temporary storage area for the CPU 80a, such as the work area. The storage device 81 is a read / write non-volatile storage device such as an HDD. Various data is stored in this storage device 81, including programs for controlling the entire color copier 1, various application programs, data for managing consumable parts, and videos showing a series of operations necessary to resolve maintenance events.

[0046] The printer control unit 82 functions as an interface for the CPU 80a to control various printer hardware components, such as the developing unit 30, photoreceptor unit 60, paper feeder 4, writing unit 34, and fuser unit 33. The image reading control unit 83 functions as an interface for the CPU 80a to control the image reading unit 2.

[0047] The control panel 65 includes an input unit that accepts user operation instructions such as a touch panel or hard keys, and a display unit such as an LCD or CRT. The control panel control unit 84 functions as an interface for the CPU 80a to control the control panel 65.

[0048] As shown in Figure 1, the inline sensor 64 is positioned between the switching claw 6c, which switches the transport destination of the paper that has left the fixing unit 33, and the paper discharge roller pair 5b, and reads the image formed on the paper as will be described later.

[0049] The lifespan setting control unit 85 has the function of performing a series of controls for setting the lifespan of the replaced reused developing unit, as described later, by executing a predetermined program on the CPU 80a. Specifically, it detects the replacement of the developing unit 30 and detects whether the replaced developing unit 30 is new or reused. If the replaced developing unit is reused, it estimates the deterioration state of the developing unit 30. Furthermore, based on the estimated deterioration state of the developing unit 30, it sets the lifespan for the replaced reused developing unit.

[0050] The CPU 80a executes a predetermined program to perform life determination control for each of the developing units 30Y, 30C, 30M, and 30K. Specifically, the CPU 80a counts the number of prints since the developing unit was replaced, and when the cumulative number of prints reaches the set lifespan, it determines that the developing unit has reached the end of its life. The CPU 80a then displays a message on the control panel 65 instructing the user to replace the developing unit that has reached the end of its life. In addition, when the cumulative number of prints approaches the set lifespan, the CPU 80a displays on the control panel 65 that there is a developing unit that has reached the end of its life and prompts the user to arrange for a replacement developing unit at the service center. Alternatively, it notifies the service center via the internet that there is a developing unit 30 that is nearing the end of its life.

[0051] Specifically, the system calculates the average number of pages printed per day based on the daily printing data, and then calculates the remaining days until the developing unit reaches the end of its lifespan based on the difference between the calculated average number of pages printed per day and the set lifespan and the cumulative number of pages printed since the developing unit was replaced. When the remaining days fall below the threshold, the system determines that the developing unit is nearing the end of its lifespan and displays a message on the control panel 65 indicating that the developing unit is nearing the end of its lifespan, or notifies the service center that there is a developing unit nearing the end of its lifespan.

[0052] In recent years, with the increasing awareness of SDGs and other initiatives, reuse and recycling are becoming increasingly important in the field of electrophotography. While market cameras are returned daily for various reasons, the developing unit 30 inside the camera is often still within its lifespan. Depending on the reason for return, unless the return is due to a malfunction or end of lifespan of the developing unit 30, it is possible to reuse the developing unit 30 from a hardware perspective. When reusing a returned developing unit 30 with remaining lifespan, it is preferable to keep the cost of the reused developing unit low by using expensive components such as the carrier and developing roller, and only replacing inexpensive components such as sealing materials and filters. However, functional components such as the carrier and developing roller directly affect the lifespan of the developing unit, and if these expensive components are used as is, the lifespan of the reused units will vary. While the control system for new products operates on the assumption that the unit will last 100% of its lifespan, the control system for reused products needs to be adjusted according to the lifespan of that particular developing unit. Reused products are also referred to as second-hand, used, or recycled products.

[0053] In this embodiment, as described above, it is preferable to determine the lifespan of the developing unit based on the cumulative number of prints since the unit was replaced, so that users and service personnel can be notified when the unit is nearing the end of its lifespan. When performing such a lifespan determination, it is necessary to accurately know the lifespan of the developing unit in advance.

[0054] Therefore, in this embodiment, when a refurbished developing unit is installed (when it is first installed in this color copier), control is implemented to estimate the deterioration state of the replaced refurbished developing unit. Based on the estimated deterioration state, the lifespan is set. The features of this embodiment will be described in detail below.

[0055] First, I will explain the detection of developing unit replacement and the detection of reused / new units. The detection of replacement of the developing unit and the detection of reused / new units can be performed, for example, by providing a non-volatile memory on the substrate of the toner density sensor 56 and detecting the information stored in the non-volatile memory.

[0056] Figure 5 is a functional block diagram showing an example of a toner concentration sensor 56. The CPU 116 and I / O port 117 of the toner density sensor 56 communicate with the CPU 80a of the main unit 10 of the color copier 1 using a communication protocol compliant with ISO 7816. The CPU 116 communicates with the CPU 80a of the main unit and reads and writes to the non-volatile memory EEPROM 121 based on a program stored in ROM 119 and commands from the CPU 80a of the main unit. The I / O port 117 is an ISO 7816-3 communication interface circuit. The system controller 118 is a circuit that controls the inside of this IC chip. ROM 119 is program memory, and RAM 120 is working memory for executing the program. The EEPROM 121, which is a storage means, is non-volatile memory. E-EEPROM 122 is a memory that stores dedicated commands for writing to EEPROM 121.

[0057] The EEPROM121 stores information such as the developer color, developer type, and serial number, as well as whether it is "new," "reused," or "already installed."

[0058] Information indicating whether an item is "new," "reused," or "installed" is stored in a designated memory address in EEPROM121. For example, if a developing unit is "new" and has never been installed in the main unit since shipment, "01h" is stored in the memory address. On the other hand, if it is a "reused" item that has been used in another copier, returned to the manufacturer for maintenance, and then shipped again, "02h" is stored in the memory address. The "reused" information in EEPROM121 is rewritten during maintenance at the recycling plant in preparation for reshipping as a reusable item.

[0059] Once installed in this color copier 1, the "installed item" is stored as "00h" at the above memory address. The "installed item" information in EEPROM 121 is rewritten at the end of the initial replacement operation that is performed when the developing unit, described later, is replaced.

[0060] For example, when the CPU 80a of the main unit 10 detects that the opening of the main unit 10 into which the developing unit 30 is attached and detached has been opened or closed, it sends the following command to the CPU 116 of the toner density sensor 56. That is, it commands the EEPROM 121 to read the information at the memory address where the information of "new," "reused," or "installed" is stored.

[0061] Based on this command, the CPU 116 of the toner density sensor 56 reads the information at the above memory address in the EEPROM 121 and transmits the read information to the CPU 80a of the main unit 10 via the I / O port 117. Based on the information at the above memory address received from the toner density sensor 56, the CPU 80a of the main unit detects whether the installed developer unit is "new," "reused," or "already installed." If the received information at the above memory address is "01h (new)" or "02h (reused)," the CPU 80a determines that the developer unit has been replaced and performs the initial replacement operation described later.

[0062] Alternatively, a detection board for detecting "new," "reused," and "installed" items may be used to detect whether a developing unit installed in the main body of the device is "new," "reused," or "installed." Figure 6 shows an example of a detection board 150 for detecting "new," "reused," and "installed" items. Figure 6(a) shows the front side of the detection board 150, and Figure 6(b) shows the back side of the detection board 150.

[0063] The detection board 150 has a first circuit section 151, which is a first electrical circuit section for detecting whether or not it is a "new" product, and a second circuit section 152, which is a second electrical circuit section for detecting whether or not it is a "reused" product. Each circuit section 151, 152 is provided with electrode sections 151a, 151b, 152a, 152b that contact the connection terminals of the device body 10, and fuse mounting sections 151c, 152c to which fuses are attached. The electrode sections 151a, 151b, 152a, 152b of each circuit section are provided on the front surface of the detection board, as shown in Figure 6(a), and the fuse mounting sections 151c, 152c are provided on the back surface of the detection board 150, as shown in Figure 6(b).

[0064] When the developing unit is "new," a fuse capable of conducting electricity is installed in the fuse mounting section 151c of the first circuit section 151. When the developing unit is a "reused item," a fuse capable of conducting electricity is installed in the fuse mounting section 152c of the second circuit section 152. During maintenance for reshipment as a reused item at the recycling plant, the detection board that was installed in the developing unit is replaced with a detection board with a fuse installed in the fuse mounting section 152c of the second circuit section 152.

[0065] When the developing unit 30 is attached to the main body 10 of the color copier 1, the connection terminals provided on the main body of the device come into contact with the electrode sections 151a, 151b, 152a, and 152b, enabling the application of voltage to the first circuit section 151 and the second circuit section 152.

[0066] For example, when the CPU 80a of the device body 10 detects that the opening of the device body 10 into which the developing unit 30 is attached and detached has been closed, it applies voltage to the first circuit section 151 and the second circuit section 152, respectively.

[0067] If the developing unit installed in the main unit 10 is "new," the first circuit section 151 is energized because it has a fuse that allows it to conduct electricity. On the other hand, the second circuit section 152 is not energized because it does not have a fuse. In this way, if only the first circuit section 151 is energized, the main unit detects that the developing unit installed in it is "new." After detecting that it is "new," the fuse is blown, and the unit is insulated. Specifically, after the initial replacement operation for the "new" developing unit, which will be described later, is completed, the fuse is blown, and the electrical state is switched from an energized state indicating that it is new to an insulated state indicating that it has been put into use.

[0068] If the developing unit installed in the main unit 10 is a "reused item," the first circuit section 151 does not receive power because it does not have a fuse, while the second circuit section 152 receives power because it has a fuse that can conduct electricity. In this way, if power is confirmed to be supplied only to the second circuit section 152, the developing unit installed in the main unit is detected as a "reused item." After detecting a "reused item," as in the case of a "new" item as described above, the fuse blows after the initial replacement operation is completed, and the electrical state switches from a powered-on state indicating that it is a reused item to an insulated state indicating that it has been put into use.

[0069] On the other hand, once installed, if the fuse in the first circuit section 151 or the second circuit section 152 is insulated, neither the first circuit section 151 nor the second circuit section 152 will be energized. Therefore, if no energization is confirmed in either the first circuit section 151 or the second circuit section 152, the installed developing unit is detected as an "installed item".

[0070] Next, we will explain the initial procedures performed when a developing unit is replaced with a "new" or "reused" unit. Figure 7 is a flowchart of the initial replacement operations performed when a developing unit is replaced with a "new" or "reused" unit. After detecting whether the item is "new," "reused," or "already installed," the initial replacement operation shown in Figure 7 is performed. If the developing unit 30 installed in the main unit 10 is an "already installed" item (YES in S1), the process ends without taking any further action.

[0071] On the other hand, when the developing unit 30 installed in the main unit 10 is "new" (NO in S1, NO in S2), initial agent adjustment is performed (S3). Initial agent adjustment is a process to adjust (calibrate) the output level of the toner density sensor 56. Specifically, the output of the toner density sensor 56 at the initial agent toner density (7 wt%) is checked, and the voltage applied to the magnetic material detection circuit 115 (see Figure 5) is adjusted so that the output of this toner density sensor 56 becomes a predetermined reference output. The adjusted voltage value is stored in the EEPROM 121 of the toner density sensor 56.

[0072] Once the initial preparation is complete, image adjustment control is performed (S4). When image adjustment control is performed, first the development potential (= development bias - exposure potential of the photoreceptor drum surface) is changed to form a tonal pattern on the intermediate transfer belt as an image adjustment pattern, consisting of multiple toner patches with different image densities. Then, the amount of toner attached to each toner patch of the tonal pattern on the intermediate transfer belt (mg / cm³) is measured. 2 This is detected by the optical sensor unit 63.

[0073] Next, as shown in Figure 8, the relationship between the amount of toner deposited on each detected toner patch and the development potential is approximated by a linear equation, "y=ax+b". The least squares method can be used for linear approximation, but is not limited to this. Next, it is checked whether the development capability (development γ), which is the slope of the linear function (y=ax+b) showing the relationship between the amount of toner deposited and the development potential, is within the target range. If the development capability (development γ) is too high compared to the target range, abnormal images such as toner scattering and background staining may occur, and if it is too low, abnormal images such as carrier adhesion (white spots) may occur. Therefore, if the determined development capability (development γ) is not the target value, the development capability (development γ) is adjusted by replenishing toner in the development unit or consuming toner. In this embodiment, the target range is 1.00±0.10 ([mg / cm 2 It is set to ] / kV).

[0074] Specifically, if the desired development capacity is higher than the target range, the target voltage value Vtref of the toner density sensor is changed to a lower value. Then, a pattern image for output is formed, consuming the toner in the developer unit to adjust the developer toner density to the changed target value. On the other hand, if the desired development capacity is lower than the target range, the target voltage value Vtref of the toner density sensor of the controlled developer is changed to a higher value. Then, toner is replenished to the developer unit to adjust the developer toner density to the changed target value.

[0075] Next, image density adjustment is performed to adjust the image formation conditions (development bias, charging bias, and exposure) to obtain the target image density. Specifically, the development potential required to obtain a predetermined target amount of toner is determined from the relationship between the determined toner deposition amount and the development potential shown in Figure 8. If the development capability is adjusted, the gradation pattern is formed again after the adjustment, and the relationship between the toner deposition amount and the development potential is recalculated.

[0076] Based on the identified development potential, the development bias is calculated. The charging bias is then determined from the calculated development bias and a predetermined background potential (the difference between the potential of the background (unexposed portion) of the photoreceptor surface and the development bias potential: in this embodiment, 150 [V]). Once the image density adjustment is complete, the cumulative number of prints used for determining the lifespan, stored in storage 81, is reset to "0" (S5). In other words, the remaining lifespan value is set to 100%.

[0077] On the other hand, when the developing unit 30 attached to the main unit 10 is a "reused item" (NO in S1, YES in S2), image adjustment control is performed without performing the initial agent adjustment described above (S6). This is because, in the case of a reused item, the initial agent adjustment has been performed in the previously used equipment, and the voltage value applied to the magnetic material detection circuit 115 (see Figure 5) is stored in the EEPROM 121 of the toner density sensor 56, so the initial agent adjustment described above is not performed. Also, in the case of a "new" item, the developer is filled with a toner density adjusted to 7 wt%, but in the case of a "reused item," the previously used magnetic carrier is filled first, and then a predetermined amount of toner is filled, so the toner density is not necessarily 7 wt%. Therefore, performing the initial agent adjustment may cause detection errors.

[0078] The same image adjustment control as for a "new" unit is performed, and once the adjustment of the development capability and image formation conditions such as development bias is complete, a deterioration state estimation mode is executed for the "reused" development unit to estimate its deterioration state (S7).

[0079] As the developing unit deteriorates, background staining, toner scattering, and carrier adhesion worsen. Therefore, in the deterioration state estimation mode of this embodiment, the deterioration state of the "reused" developing unit is detected by detecting the condition of background staining, toner scattering, and carrier adhesion.

[0080] Here, we will explain the mechanism by which background staining and toner scattering worsen as the developing unit deteriorates. Over time, the multiple V-grooves or multiple recesses formed on the outer surface of the sleeve 51a of the developing roller 51 wear down, reducing the amount of developer pumped into the sleeve 51a. This reduction in the amount of developer pumped into the sleeve 51a leads to a decrease in image density.

[0081] In this embodiment, the image adjustment control described above is performed to adjust the target voltage value Vtref of the toner density sensor 56 so that the development capability falls within the target range. As the image density decreases, the development capability falls below the target range, causing the target voltage value Vtref of the toner density sensor 56 to rise. As a result, the toner concentration of the developer increases. When the toner concentration of the developer increases, the amount of charge on the toner decreases. In addition, the ability to triboelectrically charge the toner decreases due to the deterioration of the carrier, which also reduces the charge on the toner. In this way, as the amount of charge on the toner decreases, the Coulomb force between the carrier and the toner weakens, making it easier for background staining and toner scattering to occur.

[0082] Figure 9(a) is a graph showing the relationship between background stain image density and the number of printed pages, and Figure 9(b) is a graph showing the relationship between toner splatter accumulation and the number of printed pages. As shown in Figure 9(a), it can be seen that the background stain image density increases linearly with increasing number of printed pages. Also, as shown in Figure 9(b), it can be seen that the toner splatter accumulation also increases linearly with increasing number of printed pages.

[0083] As described above, in this embodiment, the "reused" developing unit retains its original expensive components such as the carrier and developing roller. Therefore, by detecting the condition of background stains and toner scattering, it is possible to accurately detect the deterioration state of the "reused" developing unit at the time of replacement (the deterioration state of the developing roller sleeve and carrier).

[0084] Next, we will explain the mechanism by which carrier adhesion deteriorates as the developing unit degrades. The carrier consists of a magnetic core coated with resin, but over time, the resin coating wears away, reducing the carrier's electrical resistance. As a result, the carrier becomes negatively charged in the developing field of the developing area, causing it to adhere to the exposed area of ​​the photoreceptor drum, a phenomenon known as carrier adhesion. When carrier adhesion occurs, white spots appear on the image on the paper.

[0085] Figure 10 is a graph showing the relationship between the number of white spots in the image caused by carrier adhesion and the number of printed sheets. As shown in Figure 10, it can be seen that the number of white spots increases linearly with increasing print volume. In this embodiment, the carrier is used as is in the "reused" developing unit without replacement. Therefore, by detecting the number of white spots that appear in the image, the deterioration state of the "reused" unit (carrier deterioration state) at the time of replacement with the "reused" developing unit can be accurately detected.

[0086] Figure 11 is a flowchart of the degradation state estimation mode. First, the control panel 65 (see Figure 4) displays a message instructing the user to load the specified paper included in the packaging box containing the "reused" developing unit 30 into the manual feed tray 44 (S11). This is because if the type of paper is not fixed, the image density of the paper itself will not be fixed, and subsequent control cannot be performed accurately.

[0087] When the operator sets the specified paper in the manual feed tray 44 and presses the "Set Complete Button" displayed on the control panel 65, thereby detecting that the specified paper has been set (YES in S12), a background stain detection image is printed for the color of the replaced "reused" developing unit, as an image detecting the deterioration state in which background stains have become apparent (S13). This background stain detection image can be obtained by performing a blank print under image formation conditions that increase the sensitivity of background stain development (increase the background stain image density) as the deterioration of the developing unit progresses.

[0088] Figure 12 is a graph showing the relationship between soil contamination image density and soil potential. As shown in Figure 12, reducing the background potential (the difference between the potential of the background area (unexposed portion) on the photoreceptor surface and the development bias potential) increases sensitivity to background staining, which worsens as the development unit deteriorates. This makes background staining visible on the specified paper. In this embodiment, the background potential is changed from a predetermined background potential for normal printing (150[V]) to 50[V], and a blank image is printed. Specifically, at least one of the development bias and charging bias is changed from the value adjusted by the image adjustment control described above to set the background potential to 50[V], and the exposure is turned OFF to print a background stain detection image (blank print). The primary transfer conditions and secondary transfer conditions are the same as for normal printing. Note that the background potential set when printing this background stain detection image is just an example, and can be set appropriately depending on the machine.

[0089] Furthermore, if the color of the replaced "reused" developing unit is Y, M, or C, the intermediate transfer belt will be in contact with all photoreceptor drums while printing the background stain detection image (blank paper printing). At this time, to prevent background stain toner other than the color of the replaced "reused" developing unit from being transferred to the intermediate transfer belt and causing background stain color mixing, a charging bias and developing bias are applied to the colors other than the color of the replaced "reused" developing unit so that they are at the normal printing background potential (150V).

[0090] Furthermore, if multiple "reused" developing units 30 are replaced simultaneously, the background potential is changed for each color one by one, and a blank image is printed on the paper. For example, if the C color and M color developing units are replaced with "reused" developing units at the same time, first the background potential of the C color is changed, a blank image is printed, and after printing, the background potential of the C color is returned to the predetermined normal printing background potential (150V), and then the background potential of the M color is changed, and a blank image is printed.

[0091] As shown in Figure 11, following the printing of the above-mentioned background stain detection image (blank printing), a white spot detection image is printed as a deterioration state detection image in which carrier adhesion (white spots) becomes apparent (S14). This white spot detection image can be obtained by printing a solid color image under image formation conditions that are conducive to the occurrence of white spots.

[0092] Figure 13 is a graph showing the relationship between the number of white spots, the development potential, and the primary transfer current. As shown in Figure 13, it can be seen that increasing the development potential increases the number of white spots. Furthermore, it can be seen that a lower primary transfer current results in a greater number of white spots compared to a higher primary transfer current. Increasing the development potential increases the development electric field in the development region, leading to a greater number of negatively charged carriers. As a result, more carriers are developed (carriers adhering to the exposure potential of the photoreceptor drum), leading to a greater number of white spots.

[0093] The carriers attached to the photoconductor drum are negatively charged, but the amount of negative charge is less than that of the toner. Therefore, when the carriers are not transferred in the primary or secondary transfer sections, the areas where the carriers were attached become areas without toner, and these areas without toner appear as white spots on the paper.

[0094] In this embodiment, the primary transfer bias applied to the primary transfer roller is controlled by a constant current. Reducing the primary transfer current lowers the primary transfer electric field in the primary transfer section, decreasing the primary transfer rate from the photoreceptor drum to the intermediate transfer belt. As a result, carriers with a lower negative charge than the toner are hardly transferred to the intermediate transfer belt. This increases the number of white spots on the paper.

[0095] Furthermore, for white spots to become visible on the specified paper, a sufficient amount of toner must adhere to the paper, and a sufficient contrast must be created between the toner and the color of the paper. Therefore, in this embodiment, a toner image is formed on the photoreceptor drum under the image formation conditions for a solid image. As a result, even if the primary transfer current is reduced in the primary transfer section and the transfer rate is decreased, a sufficient amount of toner is transferred to the intermediate transfer belt. This ensures a sufficient image density for the image formed on the specified paper, creates a sufficient contrast between the toner and the color of the paper, and allows for good detection of white spots.

[0096] In this embodiment, the primary transfer current is set from 50 (-μA) to 1 (-μA) to perform solid image printing. This results in good contrast between the color of the specified paper and the image formed on the specified paper, and enables the production of a white spot detection image that can effectively detect white spots. The values ​​of the primary transfer current and development potential to be changed can be set as appropriate by the machine. In this embodiment, the secondary transfer conditions are the same as those for normal printing.

[0097] Furthermore, if the carrier is not ultimately transferred to the specified paper, many white spots will become apparent on the specified paper. Therefore, the primary transfer conditions may be the same as those for normal printing, while the secondary transfer conditions may be set to conditions that result in a lower transfer rate than those for normal printing. Even under such conditions, the transfer of the carrier to the paper in the secondary transfer section is suppressed, and many white spots can be made apparent on the paper.

[0098] Furthermore, in the case of white spot detection images, in order to avoid color mixing, if multiple "reused" development units 30 are replaced simultaneously, the development potential and primary transfer current are changed for each color, and white spot detection images are formed on the specified paper for each color individually.

[0099] In this way, the background stain detection image and the white spot detection image formed on each specified sheet of paper are read by the inline sensor 64, which is positioned in front of the paper discharge roller pair 5b as an image reading means (S15).

[0100] Alternatively, the standard paper with the background stain detection image formed on it and the standard paper with the white spot detection image formed on it, which have been ejected into the output tray 5a, may be placed in the image reading unit 2, and the image reading unit 2 may read the background stain detection image and the white spot detection image.

[0101] Alternatively, the soil stain detection image and the white spot detection image can be captured using a smartphone or similar device, and the captured soil stain detection image and white spot detection image can be sent to a color copier via email or app to obtain the soil stain detection image data and the white spot detection image data. This has the advantage that even an inexpensive image forming apparatus without an inline sensor 64 or image reading device 2 can perform the detection of the image density of the soil stain detection image and the number of white spots using the image forming apparatus.

[0102] However, by providing an inline sensor 64 in the paper output path of the color copier and reading the background stain detection image and white spot detection image before the paper is output to the output tray 5a, image substitution and other errors can be prevented. This is preferable because it allows for accurate assessment of the deterioration status of the replaced "reused items". Alternatively, an optional unit equipped with an inline sensor 64 may be set in the paper output section 5 inside the cylinder to read the background stain detection image and the white spot detection image.

[0103] Next, based on the scanned images of soil stains and white spots, the deterioration state of the replaced "reused item" is estimated, and its remaining lifespan is estimated (S16). First, the image density of the scanned background stain detection image is detected. Predetermined image processing is then performed on the scanned background stain detection image. For example, processing is performed to increase the contrast between the background stain toner adhering to the specified paper and the surface color of the specified paper. The background stain toner, when adhering to the surface of the specified paper printed on blank paper, changes the color of the specified paper. The more background stain toner there is, the greater the change from the original color of the specified paper, and the greater the change in the brightness of the specified paper (the image density of the background stain detection image appears higher). The change in brightness of this specified paper is detected as the image density of the background stain detection image. Since the amount of change in brightness in relation to the amount of background stain toner attached to the specified paper differs for Y, M, C, and K, for example, the detected brightness is corrected using a predetermined correction coefficient for each of Y, M, C, and K to calculate the image density of the background stain detection image.

[0104] In the above description, the image density of the background stain detection image formed on the specified paper is detected. However, the optical sensor unit 63 may also detect the amount of toner adhering to the background stain detection image on the intermediate transfer belt 32a, and the image density of the background stain detection image may be determined from the detected amount of toner adhering. This has the advantage of eliminating the need to prepare the specified paper. On the other hand, by forming the background stain detection image on a predetermined specified paper and detecting the image density of the background stain detection image on the specified paper, the influence of the surface condition of the intermediate transfer belt (filming, scratches, etc.) on the image density detection result can be eliminated. This has the advantage of enabling accurate detection of the image density of the background stain detection image.

[0105] Figure 14 is a graph showing an example of the relationship between the image density of the calculated soil contamination detection image and the remaining lifespan. As shown in Figure 9, the relationship between the number of printed pages and background stains is proportional. Therefore, as shown in Figure 14, the relationship between the image density of the background stain detection image, which increases with the increase in background stain toner, and the remaining lifespan is also proportional. For this reason, a linear function (Y1=aX1+b, Y1: image density of the background stain detection image, X1: remaining lifespan) showing the relationship between the image density of the background stain detection image and the remaining lifespan is stored in the non-volatile storage means such as ROM 80b or storage 81 of this color copier 1. From the calculated image density and the above linear function, the remaining lifespan (%) of the replaced "reused item" can be estimated.

[0106] Here, remaining lifespan is the degree of deterioration relative to a "new" developing unit. A remaining lifespan of 100% means the unit is in the same state of deterioration as a new developing unit (no deterioration: degree of deterioration 0%), and a remaining lifespan of "0%" means the unit is in the same state of deterioration as a "new" developing unit used up to its "lifespan print count" (degree of deterioration 100%).

[0107] The linear function for determining remaining lifespan described above was obtained, for example, as follows: For multiple new developing units, the image density of the background stain detection image was detected using the method described above, and the average of the detected multiple image densities was set as the image density when the remaining lifespan was 100%. Also, for multiple developing units that had reached their lifespan print count, the image density of the background stain detection image was detected using the method described above, and the average of the detected multiple image densities was set as the image density when the remaining lifespan was 0%. Then, the linear function for determining remaining lifespan described above was obtained from the set image density when the remaining lifespan was 100% and the set image density when the remaining lifespan was 0%.

[0108] Next, the remaining lifespan is calculated based on the white spot detection image that was read. First, the scanned image with detected white spots is subjected to a predetermined image processing step. This step involves processing the solid image, which has reduced image density and is formed on the specified paper, to increase the contrast with the surface color of the specified paper. Figure 15(a) shows the scanned image with detected white spots before the predetermined image processing, and Figure 15(b) shows the image with detected white spots after the predetermined image processing. As can be seen from comparing Figures 15(a) and 15(b), the image processing increases the density difference between the white spots and the solid image with reduced image density, making the white spots clearer. Once the white spots are clearer after image processing, the number of white spots is detected by counting the image portions where the image density difference (brightness difference) with the solid image with reduced image density is greater than a predetermined value, and where the size is greater than a certain value.

[0109] Alternatively, as a predetermined image processing step for the read white spot detection image, the read white spot detection image may be converted into a black and white binarized image, and the number of white spots may be detected based on the image data converted to a black and white binarized image.

[0110] Once the number of white spots is detected, the remaining lifespan is calculated based on the number of white spots. Figure 16 is a graph showing the relationship between the number of white spots detected and the remaining lifespan (%). As shown in Figure 10, the relationship between the number of printed pages and the number of white spots is proportional. Therefore, as shown in Figure 16, the relationship between the number of white spots and the remaining lifespan is also proportional. For this reason, a linear function (Y2=cX2+d, Y2: number of white spots, X2: remaining lifespan) showing the relationship between the number of white spots and the remaining lifespan is stored in the non-volatile storage means such as ROM 80b or storage 81 of this color copier 1. The remaining lifespan (%) can be estimated from the detected number of color spots and the above linear function.

[0111] The linear function for determining remaining lifespan based on the number of white spots was obtained in the same way as the linear function for determining remaining lifespan based on the background stain density. Specifically, the number of white spots is detected for multiple new developing units using the method described above, and the average value of the detected number of white spots is set as the number of white spots when the remaining lifespan is 100%. Similarly, the number of white spots is detected for multiple developing units that have reached their lifespan print count using the method described above, and the average value of the detected number of white spots is set as the number of white spots when the remaining lifespan is 0%. Then, the linear function for determining remaining lifespan is obtained from the set number of white spots when the remaining lifespan is 100% and the set number of white spots when the remaining lifespan is 0%.

[0112] In this way, once the remaining lifespan based on the background stain image density and the remaining lifespan based on the number of white spots have been determined, the degradation state estimation mode ends. After the degradation state estimation mode ends, as shown in Figure 7, the lifespan of the replaced "reused" developing unit is set, and the set developing unit lifespan (remaining lifespan) is stored in the ROM 80b or storage 81 (S8).

[0113] Specifically, the lifespan of the replaced "reused" developing unit is set based on the lower of the remaining lifespan, which is either the remaining lifespan based on the background stain density or the remaining lifespan based on the number of white spots. For example, if the lower remaining lifespan is 37%, the lifespan is set to 37% of the lifespan number that would be set when the unit is replaced with a "new" developing unit, which is pre-stored in ROM 80b or storage 81, and this lifespan number is stored in ROM 80b or storage 81. After that, the cumulative number of printed pages is reset. Alternatively, the cumulative number of printed pages stored in storage 81 or ROM 80b may be updated with a value of 63% (100% - 37%) of the lifespan number as the cumulative number of printed pages.

[0114] In this embodiment, the linear function for calculating the remaining lifespan is stored in the storage means of the color copier (storage 81 or ROM 80b), but it may also be stored in the memory of the developing unit (for example, the EEPROM 121 provided by the toner density sensor). For example, there is an advantage when the functionality of the developing unit is improved due to post-production design changes, and the developed unit with improved functionality and the developed unit before the improvement become "reused items". For example, the linear function for calculating the remaining lifespan suitable for the developed unit before the improvement may differ from the linear function for calculating the remaining lifespan suitable for the developed unit after the improvement. Therefore, by storing the linear function for calculating the remaining lifespan in the memory of the developing unit, there is an advantage in being able to set a more accurate lifespan for both the reused item before the improvement and the reused item after the improvement.

[0115] Furthermore, by storing the lifespan of the developing unit, which is set when it is replaced with a "new" developing unit, in the developing unit's memory, there is the advantage that the optimal lifespan can be set when it is replaced with a "new" developing unit with improved functionality.

[0116] Thus, in this embodiment, when the replaced developing unit is a "reused item," the image is formed under image formation conditions that increase the sensitivity to abnormal images (such as background stains and white spots) that worsen as the developing unit deteriorates. By detecting image abnormalities such as background stains and white spots that worsen as the developing unit deteriorates from the images actually formed, the deterioration state of the replaced "reused" developing unit can be accurately grasped. Then, by setting the lifespan based on the accurately grasped deterioration state of the replaced "reused" developing unit, a highly accurate lifespan determination can be made, and the occurrence of abnormal images can be suppressed.

[0117] Furthermore, in this embodiment, by understanding the deterioration state of the developing unit and setting its lifespan at the time it is replaced with a "reused" developing unit (when the "reused" developing unit is first installed), the lifespan of "reused" units can also be managed based on the cumulative number of prints and the number of prints remaining, just like "new" developing units. As a result, even for "reused" units, if the remaining number of days, calculated from the average number of prints per day and the difference between the set lifespan and the cumulative number of prints, falls below a threshold, it can be determined that the developing unit is nearing the end of its lifespan, and control can be implemented to display a message on the control panel indicating that the developing unit is nearing the end of its lifespan, or to notify the service center that there is a developing unit nearing the end of its lifespan.

[0118] Furthermore, although the developing unit is configured to be detachable from the color copier independently as described above, the photoreceptor unit 60 and the developing unit 30 may be configured as an integrated process cartridge and detachable from the color copier. Also, although the transfer unit 32 is described above as an intermediate transfer type transfer unit equipped with an intermediate transfer body, it may also be a direct transfer type that directly transfers the image of the photoreceptor to the paper. In the direct transfer type as well, when forming the white spot detection image, by lowering the absolute value of the transfer current flowing between the transfer roller and the photoreceptor drum than during normal printing, the adhesion of carriers attached to the photoreceptor drum to the paper is suppressed, making it easier for white spots to occur.

[0119] Furthermore, while the lifespan of the developing unit is determined based on the cumulative number of prints since the developing unit was replaced, the lifespan of the developing unit may also be determined based on, for example, the cumulative operating time or distance traveled by the developing unit (the sleeve of the developing roller).

[0120] Alternatively, the operator may visually detect the image density of the soil stain detection image and the number of white spots in the white spot detection image formed on the prescribed paper, and input the detection details into the control panel. Below, an embodiment in which the operator visually detects and inputs the image density of the soil stain detection image and the number of white spots in the white spot detection image into the control panel will be described as a modified example.

[0121] [Differentiation] Figure 17 is a flowchart of the mode for estimating the degradation state of modified cases. Similar to the embodiment, the developing unit 30 attached to the main body 10 of the device is detected to be a "reused item," and after image adjustment control is performed, the deterioration state estimation mode is performed.

[0122] In the modified example, when the deterioration state estimation mode is performed, the background stain detection image is printed on the specified paper, and the white spot detection image is printed on the specified paper, similar to the embodiment (S21-S24).

[0123] Next, the operator operates the control panel to input information regarding the image status, including the image density rank of the background stain detection image printed on the specified paper and the white spot rank of the white spot detection image printed on the specified paper (S25).

[0124] Specifically, once the printing of the soil stain detection image and the white spot detection image is complete, an instruction image is displayed on the display unit 65a of the control panel 65 (see Figure 4) instructing the operator to display the "Unit Replacement Settings Screen" shown in Figure 18. Based on the instruction image displayed on the display unit 65a of the control panel 65, the operator operates the control panel to display the Unit Replacement Settings Screen shown in Figure 18.

[0125] For example, press the "Settings" icon displayed on the "Home screen" shown in Figure 19 to display the settings screen. Then, press the "Printer Settings" icon displayed on the settings screen to display the printer settings screen, and from the various setting icons displayed on the printer settings screen, press the "Data Operation / Management" icon to display the "Data Operation / Management" screen. By pressing the "Unit Replacement Settings" icon displayed on the "Data Operation / Management" screen, the unit replacement settings screen shown in Figure 18 will be displayed. Alternatively, the unit replacement settings screen shown in Figure 18 may be displayed on the display section 65a of the operation panel 65 after the printing of the background stain detection image and the white spot detection image has finished.

[0126] Pressing the "Life Setting 1" icon shown in Figure 18 displays an image density rank input screen where the image density rank of the stain detection image printed on the specified paper shown in Figure 20 is entered. On the other hand, pressing the "Life Setting 2" icon shown in Figure 18 displays a white spot rank input screen where the white spot rank corresponding to the number of white spots in the white spot detection image printed on the specified paper shown in Figure 21 is entered.

[0127] As shown in Figure 20, the image density rank input screen displays multiple image density rank selection icons, each consisting of an image density rank and its reference image density. In this embodiment, there are six image density ranks, and six image density rank selection icons are displayed on the input screen. In this embodiment, there are six image density ranks, but this is not the only option; the number of ranks should be set appropriately considering the accuracy required for life setting and the ease of visual determination.

[0128] The operator compares the reference image density for each image density rank displayed on the image density rank input screen with the image density of the stain detection image printed on the specified paper, and selects the image density rank selection icon that is closest to the image density. After selecting the icon, the image density rank is confirmed by pressing the "OK" button.

[0129] When the "Print Sample Levels" icon shown in Figure 20 is pressed, the reference image density for each image density rank is printed on the paper as a reference image. By printing the reference image density for each image density rank on the paper, the background stain detection image printed on the specified paper can be compared side by side with the reference image density for each image density rank printed on the paper. This makes it easier to compare the image density of the background stain detection image printed on the specified paper compared to comparing it with the six reference image densities displayed on the display unit 65a of the operation panel 65. It also improves the accuracy of the operator's visual determination of the image density rank. Therefore, if you want to perform a more accurate visual determination, or if it is difficult to make a comparison determination from the six reference image densities displayed on the display unit 65a of the operation panel, press the "Print Sample Levels" icon to print images of the six reference image densities on the paper.

[0130] As shown in Figure 21, the white spot rank input screen displays multiple white spot rank selection icons, each consisting of a white spot rank and a range of the number of white spots corresponding to each rank. In this embodiment, there are six white spot ranks, and six white spot rank selection icons are displayed on the white spot rank input screen. In this embodiment, there are six white spot ranks, but this is not the only option; the number of white spot ranks should be set appropriately considering the accuracy required for life setting and the ease of visual determination.

[0131] Furthermore, as shown in Figure 21, the white spot rank input screen displays a sample image of the white spots that appear in the white spot detection image. The operator refers to this sample image, visually identifies the white spots in the white spot detection image printed on the specified paper, and selects the corresponding white spot rank selection icon based on the number of white spots found. After selecting an icon, the operator presses the "OK" button to confirm the white spot rank.

[0132] As shown in Figure 21, the white spot rank input screen may also be provided with an input section for the worker to input the number of white spots they have visually identified, and the control unit may determine the white spot rank from the number entered by the worker.

[0133] When the "Print White Spot Sample" icon on the white spot rank input screen is pressed, the sample image of white spots (the reference image) displayed on the white spot rank input screen is printed on the paper. By printing the sample image of white spots (i.e., the number of white spots) on the paper, it is possible to determine whether or not a spot is a white spot by placing the printed sample image near the area that appears to be a white spot on the white spot detection image printed on the specified paper. This makes it easier to refer to the sample image of white spots compared to referring to the sample image displayed on the input screen, and makes the task of finding white spots easier. It also makes it possible to distinguish white spots with high accuracy by visual inspection. Therefore, if there are areas in the white spot detection image where it is difficult to distinguish white spots, or if you want to distinguish white spots with high accuracy, press the "Print White Spot Sample" icon to print the sample image on the paper.

[0134] Next, as shown in Figure 17, the remaining lifespan of the "reused" developing unit that was replaced based on the determined image density rank is identified, and the remaining lifespan of the "reused" developing unit that was replaced based on the determined white spot rank is identified (S26).

[0135] First, we will explain how to determine the remaining lifespan based on the confirmed image density rank. Figure 22(a) illustrates how the remaining lifespan is determined when the operator selects image density rank 3, and Figure 22(b) is an example of a data table showing the relationship between the remaining lifespan and the image density rank, which is stored in the control unit's ROM or storage.

[0136] Once the operator presses the "OK" button on the image density rank input screen shown in Figure 20 to confirm the image density rank, the control unit 80 determines the remaining lifespan of the replaced "reused" developing unit from the data table shown in Figure 22(b) and the confirmed image density rank. For example, as shown in Figure 22(a), if the operator selects image density rank 3, the remaining lifespan is determined to be 70%.

[0137] The reference image density for each image density rank is the median value of the image density range for that rank. The remaining lifespan corresponding to the image density rank is the remaining lifespan corresponding to the reference image density, as shown in Figure 22(a). The remaining lifespan corresponding to the reference image density for each image density rank can be determined from the relationship between the image density of the stain detection image and the remaining lifespan shown in Figure 14.

[0138] Next, we will explain how to determine the remaining lifespan based on the white spot rank determined by the worker. Figure 23(a) illustrates how the remaining lifespan is determined when the operator selects white spot rank 3, and Figure 22(b) is an example of a data table showing the relationship between the remaining lifespan and the white spot rank, which is stored in the control unit's ROM or storage.

[0139] Once the operator presses the "OK" button on the white spot rank input screen shown in Figure 21 and the white spot rank is confirmed, the control unit 80 determines the remaining lifespan of the replaced "reused" developing unit from the data table shown in Figure 23(b) and the confirmed white spot rank. For example, as shown in Figure 23(a), when the white spot rank is 3, the remaining lifespan based on the white spot rank is determined to be 70%.

[0140] The remaining lifespan corresponding to the white spot rank shown in Figure 23(b) is the remaining lifespan corresponding to the median number of white spots for each white spot rank, as shown in Figure 23(a). The remaining lifespan for the median number of white spots for each white spot rank can be determined from the relationship between the number of white spots and the remaining lifespan shown in Figure 16.

[0141] In this way, once the remaining lifespan based on the image density rank and the remaining lifespan based on the white spot rank have been determined, the degradation state estimation mode of the modified example ends. After that, as in the embodiment, the lifespan of the replaced "reused" developing unit is set based on the lower of the remaining lifespans, which is the remaining lifespan based on the image density rank and the remaining lifespan based on the white spot rank. For example, as shown in Figures 22(a) and 23(a), if both the white spot rank and the image density rank are 3, the remaining lifespan is determined to be 70%. Then, 70% of the lifespan number of prints that is set when the developing unit is replaced with a "new" unit, which is stored in the ROM 80b or storage 81 beforehand, is set as the lifespan number of prints. The set lifespan number of prints is stored in the ROM 80b or storage 81. After that, the cumulative number of prints is reset. Alternatively, 30% (100%-70%) of the lifespan number of prints is set as the cumulative number of prints, and the cumulative number of prints count value stored in storage 81 or ROM 80b is updated.

[0142] As described above, with this modified configuration, even an image forming apparatus without an inline sensor 64 or image reading unit 2 can detect image abnormalities such as background stains and white spots that worsen as the developing unit deteriorates, from the images actually formed, and understand the deterioration state of the replaced "reused" developing unit. Therefore, it is possible to set a highly accurate lifespan with an inexpensive configuration.

[0143] Since both the background stain detection image and the white spot detection image formed on the specified paper are formed across the entire surface of the paper, there is a risk that an operator may mistakenly determine the image density rank from the white spot detection image or the white spot rank from the background stain detection image.

[0144] Therefore, the cumulative number of printed pages or cumulative mileage is stored in the EEPROM 121, which is the storage means for the toner density sensor shown in Figure 5. If the remaining life determined based on the image density rank or the remaining life determined based on the white spot rank deviates by a predetermined threshold (for example, 30% or more) from the remaining life determined based on the cumulative number of printed pages or cumulative mileage stored in the EEPROM, a warning display may be shown on the display unit 65a of the operation panel 65, as shown in Figure 24, asking whether or not to correct the selected rank. In other words, the operator is asked whether or not to re-enter the image density rank or the white spot rank. In addition to displaying a warning on the display unit 65a of the operation panel 65, the operator may also be notified by voice.

[0145] If the operator presses the "YES" button shown in Figure 24, the system transitions to the input screen shown in Figures 20 and 21, and the rank is re-evaluated. On the other hand, if the operator presses the "NO" button shown in Figure 24, the remaining lifespan is set based on the remaining lifespan determined based on the initial rank.

[0146] As described above, by pressing the icon to print a sample of the image density rank input screen or the white spot rank input screen, the reference image density for each image density rank and the white spot sample image are printed on a separate sheet of paper from the background stain detection image and the white spot detection image. However, the reference image density for each image density rank may be formed on the specified sheet of paper together with the background stain detection image, or the white spot sample image may be formed on the specified sheet of paper together with the white spot detection image. With this configuration, it becomes easier to find white spots from the image density rank of the background stain detection image and the white spot detection image compared to referring to the reference image for each image density rank or the white spot sample image displayed on the operation panel.

[0147] Furthermore, an information image to identify whether it is for image density rank determination or white spot rank determination may be formed on the specified form along with the background stain detection image and the white spot detection image. This can prevent operators from mistakenly determining the image density rank from the white spot detection image or the white spot rank from the background stain detection image.

[0148] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the spirit of the present invention as described in the claims, unless otherwise specifically limited in the above description.

[0149] The above is just one example; each of the following embodiments produces its own unique effects. (Aspect 1) An image forming apparatus comprising a developing unit 30 that is detachably attached to the main body of the apparatus and develops a latent image on a latent image carrier such as a photosensitive drum 7, and a control unit 80 that determines the lifespan of the developing unit 30, wherein the control unit 80 detects whether the replaced developing unit 30 is a reused item, and when it is detected that the replaced developing unit 30 is a reused item, it forms a deterioration state detection image (background stain detection image or white spot detection image) to grasp the deterioration state of the replaced reused developing unit, Based on the generated degradation detection image, the remaining lifespan of the refurbished developing unit is set. According to this method, the remaining lifespan of a refurbished developing unit is determined by creating a deterioration detection image to understand the deterioration state of the developing unit, and this is based on the deterioration detection image that is actually created. Since the deterioration state of the developing unit can be accurately estimated from the deterioration detection image that is actually created, an appropriate remaining lifespan can be set according to the deterioration state of the developing unit by using this image as a basis. This allows for accurate lifespan determination of refurbished developing units.

[0150] (Aspect 2) In Embodiment 1, the control unit 80 estimates the deterioration state of the refurbished developing unit based on deterioration state detection images (ground stain detection images and white spot detection images), and sets the remaining lifespan of the refurbished developing unit based on the estimated deterioration state of the refurbished developing unit. According to this method, the deterioration state of the developing unit can be accurately estimated by forming a deterioration state detection image to understand the deterioration state and then estimating from the actually formed deterioration state detection image. Then, by setting the remaining lifespan based on the accurately estimated deterioration state of the developing unit, an appropriate remaining lifespan can be set for the replaced reused developing unit according to its deterioration state, and the lifespan of the reused developing unit can be set with accuracy.

[0151] (Aspect 3) In embodiment 1 or 2, the system has an image reading means such as an inline sensor 64 that reads an image printed on a sheet such as a specified paper, and the control unit 80 forms a deterioration state detection image (ground stain detection image or white spot detection image) on the sheet, and sets the remaining lifespan of the refurbished product based on the deterioration state detection image read by the image reading means. According to this, the image forming apparatus can estimate the deterioration state of the refurbished developing unit from the deterioration state detection image and set the remaining lifespan of the refurbished developing unit. This reduces the burden on the operator compared to having the operator estimate the deterioration state of the refurbished developing unit from the deterioration state detection image formed on the sheet and input the remaining lifespan of the refurbished developing unit.

[0152] (Aspect 4) In embodiment 1 or 2, the control unit 80 has an input means such as an operation panel 65 for inputting information, and forms a deterioration state detection image (ground stain detection image or white spot detection image) on a sheet, causes the input means to input information about the image state of the deterioration state detection image formed on the sheet (in this embodiment, image density rank or white spot rank), and sets the remaining lifespan of the refurbished product based on the input information about the image state. According to this, as explained in the modified example, even an image forming apparatus that does not have an image reading means such as an inline sensor 64 that reads an image printed on a sheet such as standard paper can estimate the deterioration state of a reused developing unit that has been replaced from a deterioration state detection image and set the remaining lifespan of the reused developing unit. This makes it possible to set the lifespan of a reused developing unit with high accuracy using an inexpensive configuration.

[0153] (Aspect 5) In embodiment 4, the control unit 80 forms reference images (reference image densities for each image density rank and sample images of white spots) on the sheet for the operator to judge the image state (image density and white spots) of the deterioration state detection image (ground stain detection image and white spot detection image). According to this, as explained in Modification 1, the image state (image density and white spots) of the deterioration state detection image can be grasped by comparing the reference image formed on the sheet (reference image density for each image density rank and sample image of white spots) with the deterioration state detection image (ground stain detection image and white spot detection image). This makes it easy for the worker to visually determine the image state.

[0154] (Aspect 6) In embodiment 4, the reference image (reference image density for each image density rank, or sample image of white spots) is formed on a sheet separate from the sheet on which the deterioration state detection image is formed. According to this, as explained in Modification 1, a reference image (reference image density for each image density rank, or a sample image of white spots) can be placed next to the deterioration state detection image (ground stain detection image or white spot detection image) for comparison. This allows for accurate determination of the similarity between the visually detected deterioration state image and the reference image, and enables accurate estimation of the deterioration state of the refurbished developing unit.

[0155] (Aspect 7) In any of embodiments 4 to 6, the information relating to the image state of a deterioration state detection image, such as a soil stain detection image, is image density information such as the image density rank of the deterioration state detection image. According to this, as explained in the modified example, the deterioration status of the replaced "reused" developing unit can be accurately determined from image density information such as the image density rank of deterioration detection images, such as background stain detection images, and a highly accurate lifespan setting can be performed.

[0156] (Pattern 8) In any of embodiments 4 to 7, the information relating to the image state of a deterioration state detection image, such as a white spot detection image, is the number of white spots in the deterioration state detection image. According to this, as explained in the modified example, the deterioration status of the replaced "reused" developing unit can be accurately determined from the number of white spots, such as the white spot rank, in deterioration detection images such as white spot detection images, and a highly accurate lifespan setting can be performed.

[0157] (Aspect 9) In any of embodiments 4 to 8, the developing unit is equipped with a storage means such as an EEPROM 121 that stores information on the number of prints since the start of use or the distance traveled since the start of use. Based on the input information regarding the image state (in this embodiment, the image density rank or the white spot rank), if the remaining lifespan of the replaced reused developing unit and the remaining lifespan based on the information regarding the number of prints since the start of use or the distance traveled since the start of use stored in the storage means are more than a specified range apart, the control unit 80 asks the operator whether or not to re-input the information regarding the image state. According to this, as explained in the modified example, it is possible to prevent the lifespan of a replaced reused developing unit from being set based on incorrect image state information due to erroneous operation of input means such as the control panel.

[0158] (Aspect 10) In any of embodiments 1 to 9, the control unit 80 sets the remaining lifespan based on the deterioration state detection image (ground stain detection image or white spot detection image) only when it detects that the replaced developing unit is a reused item. According to this, the remaining lifespan is set only when the reused developing unit is first installed.

[0159] (Aspect 11) In any of embodiments 1 to 10, the device includes a charging means such as a charging member 62 that uniformly charges a latent image carrier such as a photoreceptor drum 7, an exposure means such as a writing unit 34 that exposes the surface of the uniformly charged latent image carrier to form a latent image on the surface of the latent image carrier, and a transfer means such as a transfer unit 32 that finally transfers the image on the latent image carrier developed by the developing unit 30 to a sheet. The control unit 80 sets at least one of the charging conditions of the charging means, such as a charging bias, the exposure conditions of the exposure means, such as the exposure amount, the development conditions of the developing unit, such as the development bias, and the transfer conditions of the transfer means, such as the primary transfer current, to be different from those during normal printing to form a deterioration state detection image (a background stain detection image or a white spot detection image). According to this, compared to normal printing conditions, abnormal images such as background stains and white spots that worsen as the developing unit deteriorates are more likely to appear. In other words, a deterioration state detection image can be formed under printing conditions that have increased sensitivity to abnormal images (background stains and white spots) that worsen as the developing unit deteriorates. As a result, the deterioration state of the developing unit can be accurately estimated from the deterioration state detection image, and the remaining lifespan can be set accurately.

[0160] (Aspect 12) In embodiment 11, the control unit 80 sets the surface potential to an absolute value lower than the surface potential during normal printing, and forms a deterioration state detection image. According to this, as described in the embodiment, sensitivity to background contamination that worsens as the development unit deteriorates can be increased. As a result, by detecting the background contamination state from deterioration state detection images such as background contamination detection images, the deterioration state of the development unit can be accurately estimated, and the remaining lifespan can be set accurately.

[0161] (Aspect 13) In embodiment 11, the transfer means, such as the transfer unit 32, has a transfer member, such as a primary transfer roller 32f, which is positioned opposite a latent image carrier such as a photoreceptor drum 7 and to which a transfer bias such as a primary transfer bias is applied. The control unit 80 sets the development potential to have an absolute value higher than the development potential during normal printing, forms an image on the latent image carrier under solid image printing conditions, and sets the absolute value of the transfer current, such as the primary transfer current, flowing between the latent image carrier and the transfer member to be lower than the absolute value of the transfer current during normal printing, thereby forming a degradation state detection image. According to this, as explained in the embodiment, by setting the development potential to have a higher absolute value than the development potential during normal printing, so-called carrier adhesion, where carriers adhere to the latent image carrier which deteriorates as the development unit deteriorates (carrier deterioration) progresses, becomes more likely to occur, and the sensitivity of carrier adhesion to the deterioration of the development unit (carrier deterioration) can be increased. Furthermore, by making the absolute value of the primary transfer current smaller than the primary transfer current during normal printing, it becomes more difficult for carriers attached to the latent image carrier to be transferred to the intermediate transfer body, and white spots that worsen as the development unit deteriorates (carrier deterioration) progresses become more likely to occur. In addition, by forming the image under the printing conditions for a solid image, white spots can be easily detected from deterioration state detection images such as white spot detection images formed on a sheet such as a specified paper. This allows for accurate estimation of the deterioration state of the developing unit by detecting the number of white spots from deterioration state detection images, such as white spot detection images, and enables accurate setting of the remaining lifespan.

[0162] (Aspect 14) In any of embodiments 1 to 13, the control unit 80 changes a numerical value (such as the number of prints or cumulative number of prints) for determining the lifespan of the developing unit based on the remaining lifespan of the replaced reused developing unit that has been set. This allows the remaining lifespan of the replaced refurbished developing unit to be reflected in the lifespan determination of the developing unit 30, enabling accurate determination of the lifespan of the refurbished developing unit. Furthermore, it becomes possible to determine the lifespan of refurbished items using the lifespan determination of new items, and control can be implemented to notify service personnel or users when the lifespan of refurbished items is nearing its end.

[0163] (Aspect 15) In any of embodiments 1 to 14, the developing unit has a storage means such as an EEPROM 121 that stores the installation history to the main unit of the device and whether it is a reused item, and when the developing unit is installed to the main unit of the device, the control unit 80 reads the information stored in the storage means and detects whether the developing unit has been replaced and whether the replaced developing unit is a reused item. According to this, by checking the information stored in a storage means such as the EEPROM 121 when the developing unit is installed, it is possible to detect whether the installed developing unit has been replaced, and whether the replaced developing unit is a reused item.

[0164] (Aspect 16) In embodiment 15, when the control unit 80 detects that the developing unit has been replaced, it stores the installation history in the storage means. According to this, the remaining lifespan can be set based on deterioration detection images (ground stain detection images and white spot detection images) only when the reused developing unit is first installed.

[0165] (Aspect 17) In any of embodiments 1 to 16, the developing unit 30 includes a first electrical circuit section, such as a first circuit section 151, which can switch from an electrical state such as a powered-on state indicating that it is new to an insulated state indicating that it has been put into use, and a second electrical circuit section, such as a second circuit section 152, which can switch from an electrical state such as a powered-on state indicating that it is a reused item to an insulated state indicating that it has been put into use, and the control unit 80 detects whether the developing unit has been replaced and whether the replaced developing unit is a reused item based on the electrical states of the first electrical circuit section and the second electrical circuit section. According to this, as described in the embodiment, if the first electrical circuit section, such as the first circuit section 151, is in an electrical state indicating it is new, such as being energized, it can be detected that the developing unit has been replaced with a "new" one. Also, if the second electrical circuit section, such as the second circuit section 152, is in an electrical state indicating it is a reused item, such as being energized, it can be detected that the developing unit has been replaced with a "reused" item. Furthermore, if the first and second electrical circuit sections are in an electrical state indicating they have been put into use, such as being in an insulated state, it can be detected that the installed developing unit has not been replaced.

[0166] (Aspect 18) In embodiment 17, when the control unit 80 detects that the developing unit has been replaced with a new one, it switches the first electrical circuit section, such as the first circuit section 151, to an electrical state such as an insulated state indicating that it has been put into use. When the detection means detects that the developing unit has been replaced with a reused one, it switches the second electrical circuit section to an electrical state such as an insulated state indicating that it has been put into use. According to this, after the replacement is detected, both the first electrical circuit section, such as the first circuit section 151, and the second electrical circuit section, such as the second circuit section 152, switch to an electrical state such as an insulated state, indicating that they have been put into use. This allows the remaining lifespan to be set based on deterioration detection images (ground stain detection images and white spot detection images) only when the reused developing unit is first installed. [Explanation of Symbols]

[0167] 1: Color copier 2: Image reading unit 3: Image forming unit 4: Paper feeder 5: Paper discharge section inside the cylinder 5a: Paper output tray 5b: Paper output roller pair 6: Paper transport path 6a: Normal transport route 6b: Reversal transport path 6c: Switching claw 6d: Reversing conveyor roller pair 6f: Resist Roller vs. 7: Photoconductor drum 10: Main unit of the device 11: Imaging section 12: Paper ejection space 18: Waste toner container 30: Developing Unit 31: Toner bottle 32: Transfer Unit 32a: Intermediate transfer belt 32f: Primary transfer roller 32g: Secondary transfer roller 32h: Cleaning device 33: Fixing Unit 34: Writing Unit 40: Paper feed cassette 41: Paper feed cassette 44: Manual feed tray 51: Developing roller 51a: Sleeve 51b: Magnet 52: Doctor Blade 53: First developer storage section 54: Second developer storage section 55a: First conveying screw 55b: Second conveyor screw 56: Toner density sensor 57: Toner refill port 58: Developing Case 58a: Partition member 58b: Communication port 58c: Communication port 58d: Buttocks 58e: Toner Refill Unit 59: Base component 59a: Face plate 59c: Connection part 60: Photoconductor Unit 61: Cleaning device 61a: Cleaning blade 61b: Cleaning brush roller 62: Electrostatic component 63: Optical sensor unit 64: Inline Sensor 65: Control Panel 71: Toner refill tube 71a: Toner supply port 121: EEPROM 150: Detection substrate 151:First circuit section 151a: Electrode part 151c: Fuse mounting section 152:Second circuit section 152c: Fuse mounting section [Prior art documents] [Patent Documents]

[0168] [Patent Document 1] Japanese Patent Publication No. 2012-159714

Claims

1. A developing unit is configured to be detachably attached to the main body of the device and develops the latent image on the latent image carrier, An image forming apparatus comprising a control unit for determining the lifespan of the developing unit, The control unit, The system detects whether the replaced developing unit is a reused item or not. When it is detected that the replaced developing unit is a reused item, a deterioration state detection image is formed to understand the deterioration state of the replaced reused developing unit. An image forming apparatus characterized by setting the remaining lifespan of the refurbished developing unit based on the formed deterioration state detection image.

2. An image forming apparatus according to claim 1, The control unit, Based on the aforementioned deterioration state detection image, the deterioration state of the refurbished developing unit is estimated. An image forming apparatus characterized by setting the remaining lifespan of a replaced reused developing unit based on the estimated deterioration state of the replaced reused developing unit.

3. An image forming apparatus according to claim 1, It has an image reading means for reading an image printed on a sheet, The image forming apparatus is characterized in that the control unit forms the deterioration state detection image on the sheet and sets the remaining lifespan of the refurbished product based on the deterioration state detection image read by the image reading means.

4. In the image forming apparatus according to claim 1, It has an input means for entering information, The control unit, The aforementioned deterioration state detection image is formed on a sheet, The input means is made to input information regarding the image state of the deterioration state detection image formed on the sheet. An image forming apparatus characterized by setting the remaining lifespan of a replaced reused developing unit based on the input information regarding the image state.

5. In the image forming apparatus according to claim 4, The image forming apparatus is characterized in that the control unit forms a reference image on the sheet for an operator to determine the image state of the deterioration state detection image.

6. In the image forming apparatus according to claim 4, The image forming apparatus is characterized in that the control unit forms a reference image on a sheet separate from the sheet on which the deterioration state detection image is formed, for the operator to determine the image state of the deterioration state detection image.

7. In the image forming apparatus according to claim 4, An image forming apparatus characterized in that the information relating to the image state of the deterioration state detection image is image density information of the deterioration state detection image.

8. In the image forming apparatus according to claim 4, The image forming apparatus is characterized in that the information relating to the image state of the deterioration state detection image is information relating to the number of white spots in the deterioration state detection image.

9. In the image forming apparatus according to claim 4, The developing unit is equipped with a storage means that stores information on the number of prints since the start of use or the distance traveled since the start of use. An image forming apparatus characterized in that, based on the input information regarding the image state, if the remaining lifespan of the refurbished developing unit and the remaining lifespan based on the number of prints since the start of use or the mileage since the start of use stored in the storage means are more than a specified range apart, the control unit asks the operator whether or not to re-input the information regarding the image state.

10. In the image forming apparatus according to claim 1, An image forming apparatus characterized in that it sets the remaining lifespan based on the deterioration state detection image only when it is detected that the replaced developing unit is a reused item.

11. In the image forming apparatus according to claim 1, A charging means for uniformly charging the latent image carrier, An exposure means for exposing the surface of the uniformly charged latent image carrier to form the latent image on the surface of the latent image carrier, The system comprises a transfer means for transferring the image on the latent image carrier developed by the developing unit to a sheet, The image forming apparatus is characterized in that the control unit sets at least one of the charging conditions of the charging means, the exposure conditions of the exposure means, the development conditions of the development unit, and the transfer conditions of the transfer means to be different from those during normal printing, thereby forming the deterioration state detection image.

12. In the image forming apparatus according to claim 11, The image forming apparatus is characterized in that the control unit sets the surface potential to an absolute value lower than the surface potential during normal printing, and forms the deterioration state detection image.

13. In the image forming apparatus according to claim 12, The transfer means comprises a transfer member positioned opposite the latent image carrier to which a transfer bias is applied, The image forming apparatus is characterized in that the control unit sets the development potential to have an absolute value higher than the development potential during normal printing, forms an image on the latent image carrier under solid image printing conditions, and sets the absolute value of the transfer current flowing between the latent image carrier and the transfer member to be lower than the absolute value of the transfer current during normal printing, thereby forming the degradation state detection image.

14. An image forming apparatus according to claim 1, The image forming apparatus is characterized in that the control unit changes a numerical value for determining the lifespan of the developing unit based on the remaining lifespan of the replaced reused developing unit that has been set.

15. An image forming apparatus according to claim 1, The developing unit has a storage means for storing the installation history to the main body of the device and the fact that it is a reused item. The image forming apparatus is characterized in that, when the developing unit is mounted on the main body of the apparatus, the control unit reads the information stored in the storage means to detect whether the developing unit has been replaced and whether the replaced developing unit is a reused item.

16. In the image forming apparatus according to claim 15, An image forming apparatus characterized in that, when the control unit detects that the developing unit has been replaced, the storage means stores the installation history.

17. An image forming apparatus according to claim 1, The developing unit includes a first electrical circuit section that can switch from an electrical state indicating that it is new to an electrical state indicating that it has been put into use, It includes a second electrical circuit section that can switch from an electrical state indicating that it is a reused item to an electrical state indicating that it has been put into use. The image forming apparatus is characterized in that the control unit detects whether the developing unit has been replaced and whether the replaced developing unit is a reused item, based on the electrical state of the first electrical circuit and the second electrical circuit.

18. An image forming apparatus according to claim 17, When the control unit detects that the developing unit has been replaced with a new one, it switches the first electrical circuit unit to an electrical state indicating that it has been put into use. The image forming apparatus is characterized in that, when the control unit detects that the developing unit has been replaced with a reused unit, it switches the second electrical circuit unit to an electrical state indicating that it has been put into use.

Images