Belt unit recycling method

Abstract

To enable determination as to whether parts of a belt unit are reusable or not without disassembling the belt unit.SOLUTION: A belt unit recycling method is provided, comprising a rotation step, measurement step, and determination step. A belt unit comprises a transfer belt and a drive roller in contact with an inner surface of the transfer belt. The rotation step involves turning the drive roller to move the transfer belt. The measurement step involves measuring displacements of an outer surface of the transfer belt at a position in contact with the drive roller using a displacement meter while the drive roller is turning. The delamination step involves determining that the drive roller does not need to be replaced if peak heights of the measured displacements are less than a given threshold.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a method for recycling a belt unit having a transfer belt and a drive roller that contacts the inner surface of the transfer belt. [Background technology]

[0002] Conventionally, there is known a technique for recycling toner cartridges for image forming devices (see Patent Document 1). From the viewpoint of utilizing resources sustainably, it is desirable to recycle as many parts as possible.

[0003] The condition of a belt unit of an image forming apparatus varies depending on the usage situation. For example, if a foreign object adheres between the outer surface of the drive roller of the belt unit and the inner surface of the belt, it appears as a protrusion on the outer surface of the belt. If a protrusion is present on the outer surface of the belt, there is a risk of false detection when reading the adjustment toner image printed on the outer surface of the belt. It is known to use a sensor to detect such protrusions (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-210304 [Patent Document 2] Japanese Patent Publication No. 2020-154113 Summary of the Invention [Problem to be solved by the invention]

[0005] When recycling a belt unit, it is necessary to disassemble the belt unit to check for and remove any foreign matter between the outer surface of the belt unit's drive roller and the inner surface of the belt. However, disassembling all used belt units would increase the number of processes and increase costs. Therefore, it is desirable to reuse used belt units that are in good condition without disassembly.

[0006] Therefore, an object of the present disclosure is to provide a belt unit recycling method that can determine the need for replacement or cleaning of belt unit parts without disassembling the used belt unit. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present disclosure provides a belt unit recycling method including a rotating step, a measuring step, and a determining step. The belt unit includes a transfer belt and a drive roller that contacts the inner surface of the transfer belt. In the rotation process, the transfer belt is moved by rotating the drive roller. In the measurement step, while the drive roller is being rotated, a displacement meter is used to measure the displacement of the outer surface of the transfer belt at the position where it contacts the drive roller. In the determination step, if the height of the peak of the measured displacement is smaller than a predetermined threshold value, it is determined that replacement of the drive roller is not necessary.

[0008] When the drive roller is rotating, a displacement meter is used to measure the displacement of the outer surface of the transfer belt at the position where it contacts the drive roller, and if the peak height of the measured displacement is smaller than a predetermined threshold, it is determined that the drive roller does not need to be replaced.This makes it possible to determine whether the parts of the belt unit are reusable without disassembling the used belt unit.

[0009] In the judgment process, if the height of the peak of the measured displacement is equal to or greater than a predetermined threshold, it may be judged that a protrusion is present, and if the number of protrusions is equal to or greater than a predetermined value, it may be judged that the drive roller needs to be replaced or cleaned, or the transfer belt needs to be cleaned.

[0010] If the height of the peak of the measured displacement is equal to or greater than a predetermined threshold, it is determined that a protrusion is present, and if the number of protrusions is equal to or greater than a predetermined value, it is determined that the drive roller needs to be replaced or cleaned or the transfer belt needs to be cleaned.This makes it possible to determine the need for replacement or cleaning of the drive roller or the transfer belt without disassembling a used belt unit.

[0011] In the determination step, if two or more protrusions are detected during one rotation of the transfer belt, it may be determined that the drive roller needs to be replaced or cleaned.

[0012] If two or more protrusions are detected during one rotation of the transfer belt, it is determined that the drive roller needs to be replaced or cleaned, making it possible to determine the need for replacement or cleaning of the drive roller without disassembling the used belt unit.

[0013] In the determination step, if only one protrusion is detected during one rotation of the transfer belt, it may be determined that cleaning of the transfer belt is necessary.

[0014] If only one protrusion is detected during one rotation of the transfer belt, it is determined that the transfer belt needs to be cleaned, making it possible to determine the need for cleaning the transfer belt without disassembling a used belt unit.

[0015] The position at which the displacement of the outer surface of the transfer belt is detected may be a position in the longitudinal direction of the drive roller through which the adjusting toner image formed on the outer surface of the transfer belt passes.

[0016] By detecting the displacement of the outer surface of the transfer belt at a position in the longitudinal direction of the drive roller where the adjustment toner image formed on the outer surface of the transfer belt passes, false detections can be suppressed when reading the adjustment toner image in a reused belt unit.

[0017] In the judgment process, if the height of the peak of the measured displacement is equal to or greater than a predetermined threshold, it is judged that a protrusion is present, and the detection period of the protrusion is compared with the rotation period of the drive roller. If the detection period of the protrusion and the rotation period of the drive roller match, it is judged that the drive roller needs to be replaced or cleaned, and if the detection period of the protrusion and the rotation period of the drive roller do not match, it is judged that the transfer belt needs to be cleaned.

[0018] If the height of the measured displacement peak is equal to or greater than a predetermined threshold, it is determined that a protrusion is present; if the detection period of the protrusion matches the rotation period of the drive roller, it is determined that the drive roller needs to be replaced or cleaned; and if the detection period of the protrusion does not match the rotation period of the drive roller, it is determined that the transfer belt needs to be cleaned.This makes it possible to determine the need to replace or clean the drive roller or clean the transfer belt without disassembling a used belt unit. [Effects of the Invention]

[0019] According to the present disclosure, it is possible to determine whether parts of a belt unit are reusable without disassembling the used belt unit. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a cross-sectional view illustrating an example of an image forming apparatus. [Figure 2] FIG. 2 is a perspective view showing a belt unit and an optical sensor. [Figure 3] FIG. 1 is a diagram illustrating an example of an inspection device for a belt unit. [Figure 4] 4 is a flowchart of a belt unit recycling method according to the first embodiment. [Figure 5] 10 is a flowchart of a belt unit recycling method according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] Next, the first embodiment of the present disclosure will be described in detail with reference to the drawings as appropriate. As shown in FIG. 1, a laser printer 1 as an example of an image forming apparatus includes a main body housing 10, a supply unit 20, an image forming unit 30, a discharge unit 60, a belt cleaner 90, and a control unit 100.

[0022] The supply unit 20 includes a supply tray 21 and a sheet supply device 22. The supply tray 21 is a tray that stores sheets S. The sheet supply device 22 transports the sheets S in the supply tray 21 toward the image forming unit 30.

[0023] The image forming section 30 includes an exposure device 40, four process cartridges 50, a belt unit 70, and a fixing device 80.

[0024] The exposure device 40 includes a plurality of LED units and exposes a photosensitive drum 51, which will be described later.

[0025] The process cartridge 50 includes a photosensitive drum 51, a charger 52, a developing roller 55, a toner storage chamber 56, etc. The process cartridge 50 includes four process cartridges 50Y, 50M, 50C, and 50K corresponding to toners of yellow, magenta, cyan, and black, respectively. The multiple process cartridges 50Y, 50M, 50C, and 50K are arranged in the order of yellow, magenta, cyan, and black from upstream to downstream in the conveyance direction of the sheet S. Hereinafter, when distinguishing between the colors yellow, magenta, cyan, and black, the reference numerals will be suffixed with Y, M, C, and K, respectively.

[0026] Each charger 52 faces the corresponding photosensitive drum 51. Each charger 52 charges the corresponding photosensitive drum 51.

[0027] Each developing roller 55 faces the corresponding photosensitive drum 51 .

[0028] The belt unit 70 includes a drive roller 71, a driven roller 72, a transfer belt 73 as an example of a belt, four transfer rollers 74, and a backup roller 75.

[0029] The driving roller 71 and the driven roller 72 are rollers that rotate the transfer belt 73. The driving roller 71 and the driven roller 72 are in contact with the inner surface of the transfer belt 73.

[0030] The transfer belt 73 is a belt that transports the sheet S between the photosensitive drums 51. The outer surface of the transfer belt 73 faces each of the photosensitive drums 51. The transfer rollers 74 sandwich the transfer belt 73 between themselves and the photosensitive drums 51.

[0031] The backup roller 75 comes into contact with the inner surface of the transfer belt 73, and sandwiches the transfer belt 73 between itself and a cleaning roller 91 of a belt cleaner 90, which will be described later.

[0032] The fixing device 80 includes a heating roller 81 and a pressure roller 82. The heating roller 81 includes a halogen heater 81A therein. The pressure roller 82 sandwiches the sheet S between itself and the heating roller 81.

[0033] In the image forming unit 30, first, the surface of the photosensitive drum 51 is charged by the charger 52 and then exposed by the exposure device 40. As a result, an electrostatic latent image is formed on the photosensitive drum 51. Thereafter, toner is supplied from the development roller 55 to the electrostatic latent image, thereby forming a toner image on the photosensitive drum 51. In this embodiment, the toner has, as an example, a positively charged characteristic.

[0034] Next, the sheet S supplied onto the transfer belt 73 passes between the photosensitive drum 51 and the transfer roller 74, whereby the toner image formed on the photosensitive drum 51 is transferred onto the sheet S. Then, the sheet S passes between the heating roller 81 and the pressure roller 82, whereby the toner image transferred onto the sheet S is thermally fixed.

[0035] The discharge section 60 is configured to transport the sheet S discharged from the fixing device 80 toward the outside of the main body housing 10. The discharge section 60 includes a transport roller 61 and a discharge roller 62. The sheet S discharged from the fixing device 80 is transported to the discharge roller 62 by the transport roller 61, and is discharged onto the discharge tray 11 by the discharge roller 62.

[0036] The belt cleaner 90 includes a belt cleaning roller 91, a collection roller 92, a scraping blade 93, and a storage unit 94. The belt cleaner 90 is configured to collect the toner on the transfer belt 73 into the storage unit 94.

[0037] More specifically, the belt cleaning roller 91 comes into contact with the outer surface of the transfer belt 73 and collects toner adhering to the outer surface of the transfer belt 73. The collection roller 92 comes into contact with the belt cleaning roller 91 and collects toner on the belt cleaning roller 91. The scraping blade 93 comes into contact with the collection roller 92 and scrapes off the toner on the collection roller 92. The storage section 94 stores the toner scraped off the collection roller 92 by the scraping blade 93.

[0038] 1 and 2, the image forming unit 30 further includes an optical sensor 200. The optical sensor 200 is disposed opposite the end of the transfer belt 73 on the drive roller 71 side.

[0039] The optical sensor 200 is disposed facing the outer surface of the transfer belt 73. The optical sensor 200 is a sensor that detects the position and density of a patch image P formed on the outer surface of the transfer belt 73. Here, the patch image P is an adjustment toner image used to correct toner color misregistration and density. The patch images P are formed on the transfer belt 73 as patch images PY, PM, PC, and PK corresponding to the colors yellow, magenta, cyan, and black. The patch images P are transferred from each photosensitive drum 51 to the transfer belt 73 when correcting toner color misregistration and density. When detecting the position and density of the patch image P, the control unit 100 of the laser printer 1 forms the patch image P on the outer surface of the transfer belt 73. The control unit 100 determines the position and density of the patch image P based on the detection result of the optical sensor 200.

[0040] Used belt units 70 are collected for recycling. It is desirable to reuse belt units 70 that are in good condition. However, depending on the usage conditions of the belt unit 70, parts may need to be replaced or cleaned. In particular, if foreign matter adheres between the outer surface of the drive roller 71 and the inner surface of the transfer belt 73, it will appear as a protrusion on the outer surface of the transfer belt 73. If there is a protrusion on the outer surface of the transfer belt 73, it is undesirable because it may cause erroneous detection when reading the patch image P.

[0041] Inspection is performed to determine whether the parts can be reused without disassembling the belt unit 70. Fig. 3 shows an example of an inspection device 300 that can be used to inspect the belt unit 70. The inspection device 300 has a support table 301 and a displacement meter 302.

[0042] The support base 301 supports the belt unit 70 so that the drive roller 71, the driven roller 72, and the four transfer rollers 74 are rotatable.

[0043] In this embodiment, the displacement meter 302 is a laser displacement meter. When the belt unit 70 is attached to the inspection device 300, the displacement meter 302 is provided so as to face the end of the transfer belt 73 on the drive roller 71 side. More specifically, the displacement meter 302 is provided so as to face a position in the longitudinal direction of the drive roller 71 through which a patch image P formed on the outer surface of the transfer belt 73 passes. The displacement meter 302 measures the displacement of the outer surface of the transfer belt 73 at the position of contact with the drive roller 71. In the case of a laser displacement meter, the displacement of the outer surface of the transfer belt 73 is calculated from the relative distance (mm) between the outer surface of the transfer belt 73 and the displacement meter 302. The measured displacement is acquired as a profile of the change in position of the outer surface of the transfer belt 73 as the outer surface moves.

[0044] Next, a description will be given of a method for recycling the belt unit 70 using the inspection device 300. The belt unit 70 to be inspected is attached to the inspection device 300 so that the end of the transfer belt 73 on the drive roller 71 side faces the displacement meter 302.

[0045] The recycling method for the belt unit 70 includes a rotating step, a measuring step, and a determining step. In the rotating step, the drive roller 71 is rotated by a motor (not shown), thereby moving the transfer belt 73.

[0046] In the measurement step, the displacement meter 302 measures the displacement of the outer surface of the transfer belt 73 at the position where it contacts the drive roller 71 while the drive roller 71 is being rotated.

[0047] In the determination process, the inspection device 300 detects the peak of the measured displacement. The inspection device 300 calculates the height of the peak. In this embodiment, the peak height is calculated by subtracting the design dimension value (the ideal distance when there are no protrusions) between the outer surface of the transfer belt 73 and the displacement meter 302 from the measured distance between the outer surface of the transfer belt 73 and the displacement meter 302. If the peak height is smaller than a predetermined threshold, it is determined that replacement of the drive roller 71 is unnecessary. Furthermore, if the height of the measured peak of the displacement is equal to or greater than a predetermined threshold, it is determined that there are protrusions, and if the number of protrusions is equal to or greater than a predetermined value, it is determined that replacement or cleaning of the drive roller 71 or cleaning of the transfer belt 73 is necessary.

[0048] Specifically, if two or more protrusions are detected during one rotation of the transfer belt 73, it is determined that the drive roller 71 needs to be replaced or cleaned. The drive roller 71 rotates two or more times during one rotation of the transfer belt 73. Therefore, if two or more protrusions are detected during one rotation of the transfer belt 73, it is determined that foreign matter that is causing the protrusions is attached to the drive roller 71. The drive roller 71 can be cleaned, for example, by pressing a rubber blade against the surface of the drive roller 71 to remove the foreign matter, and then wiping the drive roller 71 with a rag soaked in alcohol. After cleaning the drive roller 71, the belt unit 70 is inspected again.

[0049] If only one protrusion is detected during one rotation of the transfer belt 73, it is determined that cleaning of the transfer belt 73 is necessary. In other words, if only one protrusion is detected during one rotation of the transfer belt 73, it is determined that foreign matter is attached to the transfer belt 73. The transfer belt 73 is cleaned, for example, by wiping the transfer belt 73 with a rag soaked in alcohol.

[0050] The principle of peak detection is not particularly limited. The presence or absence of a peak may be determined visually by an operator, or may be determined by a computer using an existing algorithm. Furthermore, the principle of determining the peak height is also not limited. The peak height may be determined by an operator drawing a baseline in a peak-free area and determining the height from the difference between the peak and the baseline, or may be calculated by a computer using an existing algorithm.

[0051] Next, a method for recycling the belt unit 70 according to this embodiment using the inspection device 300 will be described with reference to the flowchart of FIG.

[0052] With the belt unit 70 attached to the inspection device 300, the drive roller 71 is rotated by a motor (not shown) to move the transfer belt 73 (S1).

[0053] After step S1, the displacement of the outer surface of the transfer belt 73 at the position where it contacts the drive roller 71 is measured using the displacement meter 302 (S2). Next, the displacement peak is detected from the measurement data, and it is determined whether the height of the displacement peak is equal to or greater than a threshold (S3). If the height of the displacement peak is equal to or greater than the threshold (S3, Yes), it is determined that a protrusion is present, and the protrusion is counted (S4), and the process proceeds to step S5. If the height of the displacement peak is less than the threshold (S3, No) in step S3, the process proceeds directly to step S5.

[0054] In step S5, it is determined whether the measurement data has ended, and if it has ended (S5, Yes), the process proceeds to step S6. If the measurement data has not ended (S5, No), the process returns to step S3, and steps S3 to S5 are repeatedly executed until the measurement data has ended.

[0055] In step S6, it is determined whether the number of protrusions per revolution of the transfer belt 73 is less than one. If the number of protrusions per revolution of the transfer belt 73 is less than one, that is, if there are no protrusions (S6, Yes), it is determined that replacement and cleaning of the drive roller is not necessary (S7). If the number of protrusions per revolution of the transfer belt 73 is one or more (S6, No), the process proceeds to step S8.

[0056] In step S8, it is determined whether the number of protrusions per revolution of the transfer belt 73 is less than two. If the number of protrusions per revolution of the transfer belt 73 is less than two, that is, if there is only one protrusion (S8, Yes), it is determined that cleaning of the transfer belt 73 is necessary (S9). If the number of protrusions per revolution of the transfer belt 73 is two or more (S8, No), it is determined that replacement or cleaning of the drive roller 71 is necessary (S10). Whether to replace or clean the drive roller 71 may be determined visually by an operator, for example, or if the condition does not improve after cleaning, it may be determined that replacement is necessary.

[0057] As described above, the following effects can be obtained in this embodiment.

[0058] While the drive roller 71 is rotating, a displacement meter 302 is used to measure the displacement of the outer surface of the transfer belt 73 at the position where it comes into contact with the drive roller 71, and if the peak height of the measured displacement is smaller than a predetermined threshold value, it is determined that the drive roller 71 does not need to be replaced, thereby making it possible to determine whether the drive roller 71 can be reused as is without disassembling the used belt unit 70.

[0059] Furthermore, if the height of the measured displacement peak is equal to or greater than a predetermined threshold, it is determined that a protrusion is present; if two or more protrusions are detected during one rotation of the transfer belt 73, it is determined that the drive roller 71 needs to be replaced or cleaned; and if only one protrusion is detected, it is determined that the transfer belt 73 needs to be cleaned. This makes it possible to determine the need for replacement or cleaning of the drive roller 71 or the transfer belt 73 without disassembling the used belt unit 70.

[0060] Since the position where the displacement of the outer surface of the transfer belt 73 is detected is the position where the patch image P formed on the outer surface of the transfer belt 73 passes in the longitudinal direction of the drive roller 71, erroneous detection can be suppressed when reading the patch image P in a reused belt unit 70.

[0061] Next, a second embodiment of the present disclosure will be described in detail. This embodiment is a method for recycling a belt unit 70 using the inspection device 300 according to the first embodiment, and includes the same rotation process and measurement process as the first embodiment. The same components as those in the first embodiment are designated by the same reference numerals, and their description will be omitted.

[0062] In the determination process of this embodiment, the peak of the measured displacement is detected, and if the height of the peak is smaller than a predetermined threshold, it is determined that replacement of the drive roller 71 is not necessary. Furthermore, if the height of the peak of the measured displacement is equal to or greater than a predetermined threshold, it is determined that a protrusion is present. The protrusion detection period is then calculated and compared with the rotation period of the drive roller 71. In this embodiment, the protrusion period is calculated by, for example, storing the time at which the protrusion is detected and calculating it from the stored detection time. Note that the "time at which the protrusion is detected" here refers to a position on the time axis in the measurement data, for example, the time of day. The rotation period of the drive roller is constant.

[0063] If the protrusion detection period and the rotation period of the drive roller 71 match, it is determined that replacement or cleaning of the drive roller 71 is necessary. In other words, if the protrusion detection period and the rotation period of the drive roller 71 match, it is determined that foreign matter is attached to the drive roller 71. If the protrusion detection period does not match the rotation period of the drive roller 71, it is determined that cleaning of the transfer belt 73 is necessary. In other words, if the protrusion detection period does not match the rotation period of the drive roller 71, it is determined that foreign matter is attached to the transfer belt 73.

[0064] Next, an example of a method for recycling the belt unit 70 using the inspection device 300 will be described with reference to the flowchart of FIG.

[0065] With the belt unit 70 attached to the inspection device 300, the drive roller 71 is rotated by a motor (not shown) to move the transfer belt 73 (S11).

[0066] After step S11, the displacement of the outer surface of the transfer belt 73 at the position where it contacts the drive roller 71 is measured using the displacement meter 302 (S12). Next, the displacement peak is detected from the measurement data, and it is determined whether the height of the displacement peak is equal to or greater than a threshold (S13). If the height of the displacement peak is equal to or greater than the threshold (S13, Yes), it is determined that a protrusion is present, and the time when the protrusion was detected is stored (S14), and the process proceeds to step S15. If the height of the displacement peak is less than the threshold (S13, No) in step S13, the process proceeds directly to step S15.

[0067] In step S15, it is determined whether the measurement data has ended, and if it has ended (S15, Yes), the process proceeds to step S16. If the measurement data has not ended (S15, No), the process returns to step S13, and steps S13 to S15 are repeatedly executed until the measurement data has ended.

[0068] In step S16, it is determined whether the number of times that a protrusion is detected during one rotation of the transfer belt 73 is less than one. If the number of times that a protrusion is detected during one rotation of the transfer belt 73 is less than one, that is, if no protrusion is detected (S16, Yes), it is determined that replacement and cleaning of the drive roller 71 is unnecessary (S17). If the number of times that a protrusion is detected during one rotation of the transfer belt 73 is one or more (S16, No), the process proceeds to step S18.

[0069] In step S18, it is determined whether the protrusion detection period and the rotation period of the drive roller 71 match. If the protrusion detection period and the rotation period of the drive roller 71 do not match (S18, No), it is determined that cleaning of the transfer belt 73 is necessary (S19). If the protrusion detection period and the rotation period of the drive roller 71 match (S18, Yes), it is determined that replacement or cleaning of the drive roller 71 is necessary (S20). Whether to replace or clean the drive roller 71 may be determined visually by an operator, for example, or if the condition does not improve after cleaning, it may be determined that replacement is necessary.

[0070] As described above, the following effects can be obtained in this embodiment.

[0071] If the height of the peak of the measured displacement is equal to or greater than a predetermined threshold, it is determined that a protrusion is present; if the detection period of the protrusion matches the rotation period of the drive roller 71, it is determined that the drive roller 71 needs to be replaced or cleaned; and if the detection period of the protrusion does not match the rotation period of the drive roller 71, it is determined that the transfer belt 73 needs to be cleaned.This makes it possible to determine the need for replacement or cleaning of the drive roller 71 or cleaning of the transfer belt 73 without disassembling the used belt unit 70.

[0072] The present disclosure is not limited to the above-described embodiment, but can be used in various forms as exemplified below.

[0073] In the above embodiment, the displacement meter 302 is an optical type, but it may also be a contact type or an ultrasonic type.

[0074] In the above-described embodiment, it is determined that cleaning of the transfer belt 73 is necessary when only one protrusion is detected during one rotation of the transfer belt 73 or when the protrusion detection cycle does not match the rotation cycle of the drive roller 71. However, it may also be determined that replacement of the transfer belt 73 is necessary instead of cleaning the transfer belt 73.

[0075] In the above-described embodiment, it is determined that replacement or cleaning of the drive roller 71 is necessary when two or more protrusions are detected during one rotation of the transfer belt 73 or when the protrusion detection cycle matches the rotation cycle of the drive roller 71. However, it may be determined that replacement or cleaning of the drive roller 71 is necessary instead of determining that replacement or cleaning of the drive roller 71 is necessary.

[0076] In the first embodiment, the need for replacement or cleaning of the drive roller 71 or the transfer belt 73 itself is determined based on the number of protrusions during one rotation of the transfer belt 73, but it is not necessary to rotate the transfer belt 73 one full rotation to count the protrusions. If the transfer belt 73 is rotated a distance corresponding to at least one rotation of the drive roller 71, foreign matter adhering to the drive roller 71 can be detected.

[0077] In the second embodiment, protrusions are detected during one rotation of the transfer belt 73, but it is not necessary to rotate the transfer belt 73 one full rotation to detect protrusions. If the transfer belt 73 is rotated by a distance corresponding to at least two rotations of the drive roller 71, the protrusion detection period can be obtained.

[0078] The elements described in the above-described embodiment and modified examples may be implemented in any combination. [Explanation of symbols]

[0079] 70 Belt unit 71 Drive roller 73 Transfer belt 302 Displacement meter

Claims

1. A method for recycling a belt unit having a transfer belt and a drive roller that contacts an inner surface of the transfer belt, comprising: a rotating step of rotating the drive roller to move the transfer belt; a measuring step of measuring a displacement of the outer surface of the transfer belt at a position where the outer surface contacts the drive roller using a displacement meter while the drive roller is being rotated; and a determining step of determining that replacement of the drive roller is not necessary if the height of the measured peak of the displacement is smaller than a predetermined threshold value.

2. In the determination step, If the height of the peak of the measured displacement is equal to or greater than the predetermined threshold, it is determined that a protrusion is present; 2. The method for recycling a belt unit according to claim 1, wherein if the number of the protrusions is equal to or greater than a predetermined value, it is determined that the drive roller or the transfer belt needs to be replaced or cleaned.

3. 3. The belt unit recycling method according to claim 2, wherein, in the determination step, if two or more protrusions are detected during one rotation of the transfer belt, it is determined that the drive roller needs to be replaced or cleaned.

4. 3. The belt unit recycling method according to claim 2, wherein, in the determination step, if only one protrusion is detected during one rotation of the transfer belt, it is determined that cleaning of the transfer belt is necessary.

5. 2. The method for recycling a belt unit according to claim 1, wherein the position at which the displacement of the outer surface of the transfer belt is detected is a position in the longitudinal direction of the drive roller through which an adjustment toner image formed on the outer surface of the transfer belt passes.

6. In the determination step, If the height of the peak of the measured displacement is equal to or greater than the predetermined threshold, it is determined that a protrusion is present; comparing the detection period of the protrusion with the rotation period of the drive roller; If the detection period of the protrusions and the rotation period of the drive roller coincide, it is determined that the drive roller needs to be replaced or cleaned; 2. The method for recycling a belt unit according to claim 1, wherein if the detection period of the protrusions does not coincide with the rotation period of the drive roller, it is determined that cleaning of the transfer belt is necessary.

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