JP7287214B2 - Image forming apparatus and control method - Google Patents

Description

The present disclosure relates to a technique of forming an image by electrophotography using a two-component developer.

2. Description of the Related Art In an electrophotographic image forming apparatus, image formation is performed by an electrostatic copying process, and toner is consumed each time an image is formed.

In a two-component development method using a charged toner and a magnetic carrier as a development method used for image formation, a developing bias and charging of the photoreceptor are required so that the carrier does not move from the developer carrier to the photoreceptor. state is adjusted. However, depending on the situation in which the image forming apparatus is used, for example, when the power of the image forming apparatus is turned on, when the power is turned off, when a jam occurs, etc., the adjustment of the potential of the developing bias or the like is not stable. A minute amount of carrier may migrate to the photoreceptor.

When the carrier moves from the developer carrier to the photoreceptor, the photoreceptor and intermediate transfer belt deteriorate. In the photoreceptor, cleaning the carrier adhering to the peripheral surface of the photoreceptor promotes abrasion of the photoreceptor layer on the peripheral surface, eventually causing charging failure. Further, in the intermediate transfer belt, the carrier causes unevenness on the surface thereof, and toner and the like remain in the recessed portions, resulting in cleaning failure. This results in poor image quality.

According to Japanese Patent Application Laid-Open No. 2002-200001, paper dust, toner, and the like are deposited on the peripheral surface of the intermediate transfer belt, degrading the transfer performance. In order to know when to replace the deteriorated intermediate transfer belt, the relationship between the secondary transfer voltage level and the damage coefficient on the intermediate transfer belt is determined. For example, when the secondary transfer voltage levels are "1", "2" and "3", the damage coefficients for monochrome image formation are "1", "1.2" and "1.5", respectively. ” is defined. A damage index is calculated by integrating this damage coefficient and the operation time of each means under predetermined image forming conditions, and then the cumulative value of the damage index is calculated for the entire operation period. The life of the intermediate transfer belt is defined as the time when this cumulative value reaches a certain value (for example, 35000). When the cumulative value exceeds a certain value, a display prompting the user to replace the intermediate transfer belt is displayed.

JP-A-2000-305379

However, as in Japanese Patent Application Laid-Open No. 2002-100001, when it is determined that the intermediate transfer belt has reached the end of its service life when the cumulative value of the damage index exceeds a certain value for all image forming apparatuses, the intermediate transfer belt has Due to variations, there are individual differences, so in practice, it may be wasteful to replace the intermediate transfer belt that has not reached the end of its service life. Conversely, when it is determined that the intermediate transfer belt has reached the end of its service life, due to individual differences, some intermediate transfer belts have already reached the end of their service life, and as a result, the image quality is degraded. There is also

Moreover, the same problem occurs not only with the intermediate transfer belt but also with the photosensitive member.

The present disclosure solves the above problems, and provides an image forming apparatus and a control method capable of predicting the life of a photoreceptor included in the image forming apparatus even when variations exist during manufacturing. intended to

In order to achieve the above object, one aspect of the present disclosure is an image forming apparatus that develops an electrostatic latent image on a surface of a photoreceptor with toner transported by a developer carrier that carries developer containing toner and carrier. and storing a first correspondence indicating a change in film thickness of the photoreceptor with respect to the amount of operation of the image forming apparatus according to the amount of movement of the carrier from the developer bearing member to the photoreceptor due to manufacturing variations. estimating means for estimating the amount of movement of the carrier in the initial stage of use of the image forming apparatus; referring to the first correspondence based on the amount of movement of the carrier obtained by the estimation; and acquisition means for acquiring, as the lifetime of the photoreceptor, an operation amount corresponding to the film thickness to be reached.

Here, further comprising an intermediate transfer member onto which a toner image formed by developing the electrostatic latent image is transferred, and part of the carrier that has moved to the photosensitive member is transferred to the peripheral surface of the intermediate transfer member. The storage means further stores a second correspondence showing the transition of the number of carrier dents on the peripheral surface of the intermediate transfer member with respect to the amount of work in accordance with the amount of movement of the carrier caused by manufacturing variations. Further, the obtaining means refers to the second correspondence based on the movement amount of the carrier obtained by the estimation, and obtains the operation amount corresponding to the number of dents reaching the end of life of the intermediate transfer member. As a lifetime, you may acquire.

Here, the storage means further includes a third correspondence indicating a change in the amount of movement of the carrier from the developer carrier to the photoreceptor with respect to the transport amount of the developer on the developer carrier caused by manufacturing variations. The estimating means refers to the auxiliary estimating means for estimating the conveyed amount of the developer conveyed by the developer bearing member in the initial stage, and the third correspondence relation, and by estimating The apparatus may include movement amount acquisition means for acquiring a movement amount of the carrier corresponding to the obtained conveyance amount of the developer.

Here, the storage means further stores a fourth correspondence relationship indicating a change in the predetermined developing bias applied to the developer bearing member with respect to the transport amount of the developer on the developer bearing member due to manufacturing variations. By switching the developing bias applied to the developer carrying member, the density of the toner image formed on the photoreceptor is changed. development bias acquisition means for developing the electrostatic latent image of , and obtaining a development bias that provides a predetermined toner density; It may include a transport amount acquisition means for acquiring.

Here, the storage means further stores a predetermined development value applied to the developer carrier for the transport amount of the developer on the developer carrier caused by manufacturing variations in accordance with environmental information that fluctuates depending on the environment. A fifth correspondence relationship indicating changes in bias is stored, and by switching the developing bias applied to the developer bearing member, the density of the toner image formed on the photosensitive member varies, and the secondary estimation means is an environment information acquisition means for acquiring environment information; a development bias acquisition means for developing an electrostatic latent image of a predetermined pattern in the initial stage to obtain a development bias that provides a predetermined toner density; The apparatus may include transport amount acquisition means for acquiring a transport amount of the developer corresponding to the obtained developing bias by referring to the fifth correspondence relationship according to the environment information.

Here, it is also possible to further include correction means for correcting the acquired life span of the photoreceptor according to the usage status of the photoreceptor.

Here, the correcting means may correct when a recording sheet jam occurs.

Here, it is also possible to further include correction means for correcting the acquired life span of the intermediate transfer body according to the usage status of the intermediate transfer body.

Here, the correcting means may correct when a recording sheet jam occurs.

Further, one aspect of the present disclosure is a control method used in an image forming apparatus that develops an electrostatic latent image on the surface of a photoreceptor with toner transported from a developer carrier that carries a developer composed of toner and carrier. The image forming apparatus stores a first correspondence relationship indicating a change in the film thickness of the photoreceptor with respect to the amount of operation of the image forming apparatus, according to the amount of movement of the carrier to the photoreceptor due to manufacturing variations. The control method includes, in an initial stage of use of the image forming apparatus, an estimation step of estimating a carrier movement amount from the developer carrier to the photoreceptor, and a carrier movement amount obtained by the estimation. and an acquiring step of referring to the first correspondence relationship based on and acquiring the operation amount corresponding to the film thickness reaching the end of life as the life of the photoreceptor.

According to the above configuration, it is possible to predict the life of the photoreceptor included in the image forming apparatus even when there is a manufacturing variation.

1 is a diagram showing a schematic configuration of an image forming apparatus 10; FIG. 4 shows a diagram showing the configuration of an image forming unit 14. FIG. 2 is a block diagram showing the configuration of a control circuit 100; FIG. A cross-sectional view of the developer carrier 27K is shown. 4 is a graph showing changes in the amount of developer transported from a developer carrier 27K; FIG. 4 shows a cross-sectional view at a position where the developer carrier 27K and the photosensitive drum 23K are close to each other. 7 is a graph showing changes in the amount of movement of carriers from a developer carrier 27K; FIG. 7 is a diagram showing a state in which a dent (carrier dent) is formed on the circumferential surface of the intermediate transfer belt 21 by the carrier. 4 is a graph showing changes in the number of carrier dents; 5 is a graph showing changes in film thickness of a photoreceptor drum 23K; 7 is a graph showing a correspondence relationship between a developing bias corresponding to a case where a predetermined toner density is obtained and a transport amount/Ds; 7 is a graph showing changes in the number of carrier dents when trouble occurs. 4 is a flow chart showing operations related to life estimation and replacement of the intermediate transfer belt 21 and the photosensitive drum 23K. 5 is a flow chart showing an operation of estimating the life of an intermediate transfer belt and a photosensitive drum;

1 Embodiment An image forming apparatus 10 as one embodiment according to the present disclosure will be described with reference to the drawings.

1.1 Image forming apparatus 10
The image forming apparatus 10, as shown in FIG. 1, is a tandem-type color multifunction peripheral (MFP: MultiFunction Peripheral) having the functions of a scanner, a printer, and a copier.

As shown in this figure, the image forming apparatus 10 is provided with a paper feeding section 13 for storing and feeding recording sheets at the bottom of the housing. A printer 12 that forms an image by electrophotography is provided above the paper feeding unit 13 . Further above the printer 12, there are provided an image reader 11 that reads a document and generates image data, and an operation panel 19 that displays an operation screen and accepts input operations from the user. A humidity sensor 41 for measuring the internal humidity is provided inside the housing.

The image reader 11 has an automatic document feeder. The automatic document feeder conveys the documents set on the document tray one by one to the document glass plate via the transport path. The image reader 11 reads a document conveyed to a predetermined position on the document glass plate by an automatic document feeder or an image placed on the document glass plate by the user by moving the scanner. Image data consisting of green (G) and blue (B) multivalued digital signals is obtained.

The image data of each color component obtained by the image reader 11 undergoes various data processing in the control circuit 100, and furthermore, each reproduction color of yellow (Y), magenta (M), cyan (C), and black (K) is reproduced. Converted to image data.

The printer 12 includes an intermediate transfer belt 21 (intermediate transfer body) stretched by a drive roller, a driven roller, and a backup roller, a density sensor 42 that measures the density of a toner image formed on the peripheral surface of the intermediate transfer belt 21, A secondary transfer roller 22, image forming units 20Y, 20M, 20C, and 20K arranged at predetermined intervals along the running direction X of the intermediate transfer belt 21 so as to face the intermediate transfer belt 21, a fixing unit 50, a control circuit 100, and the like. consists of

The image forming units 20Y, 20M, 20C, and 20K form Y, M, C, and K toner images, respectively. Specifically, as shown in FIG. 2, the image forming unit 20K includes a photoreceptor drum 23K (photoreceptor) as an image carrier, an LED array 25K for exposing and scanning the surface of the photoreceptor drum 23K, and a charging charger 24K. , developing device 26K, cleaner and primary transfer roller 28K. The developing device 26K includes a developer carrier 27K, a regulating member 32K, and the like. The imaging units 20Y, 20M, and 20C also have the same configuration as the imaging unit 20K.

As shown in FIG. 2, in the image forming unit 20K, the photosensitive drum 23K is uniformly charged by the charging charger 24K, exposed by the LED array 25K, and an electrostatic latent image is formed on the surface of the photosensitive drum 23K. be. The electrostatic latent image is developed by a corresponding color developer to form a K-color toner image on the surface of the photosensitive drum 23K. It is transferred onto the surface of the intermediate transfer belt 21 by the electrostatic action of the roller 28K.

The image forming units 20Y, 20M, and 20C are similar to the image forming unit 20K, and transfer toner images of Y to C colors onto the surface of the intermediate transfer belt 21. FIG.

The image forming timing of each color is shifted so that the Y to K toner images are transferred in multiple layers on the intermediate transfer belt 21 .

Returning to FIG. 1, the paper feed unit 13 includes paper feed cassettes 60, 61, and 62 accommodating recording sheets of different sizes, and pickup rollers 63 and 64 for feeding the recording sheets from the respective paper feed cassettes onto the transport path. , 65.

A recording sheet is fed from one of the paper feed cassettes of the paper feed unit 13 in accordance with the image forming operations of the image forming units 20Y to 20K.

The recording sheet is conveyed on the conveying path to the secondary transfer position where the secondary transfer roller 22 and the backup roller face each other with the intermediate transfer belt 21 interposed therebetween. As a result, the Y to K toner images multiple-transferred on the intermediate transfer belt 21 are secondarily transferred to the recording sheet. The recording sheet on which the Y to K color toner images have been secondarily transferred is further conveyed to the fixing section 50 .

When the toner image on the surface of the recording sheet passes through the fixing nip formed between the heating roller 51 of the fixing section 50 and the pressure roller 52 in pressure contact therewith, the toner image is heated and pressed onto the recording sheet. After being fused and fixed on the surface, the recording sheet passes through the fixing section 50 and is delivered to the discharge tray 15 .

The operation panel 19 is provided with a display unit composed of a liquid crystal display panel or the like, and displays contents set by the user and various messages. The operation panel 19 accepts an instruction to start copying, setting of the number of copies, setting of copying conditions, setting of a data output destination, etc. from the user, and notifies the control circuit 100 of the received contents.

When it is determined that the number of sheets of the intermediate transfer belt 21 or the photoreceptor drum 23K has reached the end of its life, the operation panel 19 receives a command from the printer main control circuit 111 via the main control unit 101a and the input/output circuit 108, as will be described later. to receive a request to replace the intermediate transfer belt 21 or the photosensitive drum 23K. Upon receiving the replacement request, the operation panel 19 displays a replacement request for the intermediate transfer belt 21 or the photosensitive drum 23K.

1.2 Gap Between Developer Carrying Member 27K and Regulating Member 32K Hereinafter, the image forming section 20K will be described as a representative of the image forming sections 20Y to 20K. Note that the image forming units 20Y, 20M, and 20C also have the same configuration as the image forming unit 20K, so description of the image forming units 20Y, 20M, and 20C will be omitted.

As shown in FIG. 4, a gap 29K is provided between the peripheral surface 27Ka of the developer carrier 27K and the tip end portion 32Ka of the regulating member 32K, and the tip end portion 32Ka of the regulating member 32K is positioned at the peripheral surface 27Ka of the developer carrier 27K. A regulating member 32K is provided so as to face the side. Here, the length of the gap 29K is represented by the width Db.

The regulating member 32K regulates the amount of developer conveyed to a region (development position) facing the photosensitive drum 23K on the developer carrier 27K (amount of developer carried in this region). When the width Db is wide, the amount of developer to be transported is large. On the other hand, when the width Db is narrow, the amount of transported developer is small.

Although the width Db is within the tolerance, there are variations at the time of manufacture for each individual product (image forming apparatus 10). Therefore, the amount of developer conveyed by the developer carrier 27K also varies from product to product during manufacturing.

FIG. 5 is a graph showing changes in the amount of developer transported by the developer carrier 27K with respect to the width Db that fluctuates due to manufacturing variations. In this graph, the horizontal axis indicates the width Db, and the vertical axis indicates the transport amount of the developer by the developer carrier 27K. This graph also shows a range 201 of variations in the width Db at the time of manufacture. Range 201 ranges from lower limit 203 to upper limit 204 .

As shown by a curve 202 representing changes in the conveyed amount in this graph, the conveyed amount of the developer increases monotonously as the width Db increases.

The transport amounts corresponding to the lower limit 203 and the upper limit 204 are the transport amount B and the transport amount A, respectively.

1.3 Gap Between Developer Carrying Member 27K and Photoreceptor Drum 23K As shown in FIG. ), the distance between the peripheral surface of the developer carrier 27K and the peripheral surface of the photosensitive drum 23K is represented by the width Ds.

When a two-component developer is used, as shown in this figure, the developer containing toner and carrier adheres to the peripheral surface of the developer carrier 27K.

At the development position 30K, a voltage (development bias) is applied to the developer carrier 27K, and the electric field moves the toner contained in the developer to the latent image portion of the photosensitive drum 23K. On the other hand, the carrier contained in the developer remains on the peripheral surface of the developer carrier 27K due to the main pole magnetic force of the developer carrier 27K. Normally, by adjusting the developing bias and the surface potential of the photoreceptor drum 23K, only the toner moves to the peripheral surface of the photoreceptor drum 23K, and the carrier does not move to the photoreceptor drum 23K side.

1.4 Adhesion of Carrier to Photoreceptor Drum 23K As described above, normally, the carrier contained in the developer does not move from the developer carrier 27K to the photoreceptor drum 23K side.

However, depending on the operating conditions of the image forming apparatus 10, a very small amount of carrier may move to the photosensitive drum 23K. The amount of movement is related to the transport amount/Ds and the strength of the magnetic force that keeps the carrier on the developer carrier 27K.

FIG. 7 is a graph showing changes in the amount of carrier movement from the developer carrier 27K.

As shown in FIG. 7, when the amount of developer transported is large, the width Ds is narrow, and the magnetic force of the developer carrier 27K is weak, the carrier tends to move toward the photosensitive drum 23K.

In this figure, the horizontal axis indicates the transport amount/width Ds, and the vertical axis indicates the amount of movement of the carrier to the photosensitive drum 23K. Further, a curve 211 of change in carrier movement amount when the magnetic force is large is shown, and a curve 212 of change in carrier movement amount is shown when the magnetic force is small.

Both when the magnetic force is large and when the magnetic force is small, the movement amount of the carrier monotonically increases with the increase of the transport amount/Ds. Further, in the entire range of the transport amount/Ds, the movement amount of the carrier when the magnetic force is small is larger than the movement amount of the carrier when the magnetic force is large.

The transport amount/Ds (B216) and (A217) shown in FIG. 7 respectively correspond to the transport amounts B206 and A205 shown in FIG.

The carrier movement amount B1 is the carrier movement amount in the case of the transport amount/Ds (B216). Further, the carrier movement amounts A1 and A2 are the carrier movement amounts when the magnetic force is large (211) and when the magnetic force is small (212), respectively, in the case of the transport amount/Ds (A217).

As described above, FIG. 7 shows the third correspondence relationship showing the change in the amount of carrier movement from the developer carrier 27K to the photosensitive drum 23K with respect to the amount of developer transported on the developer carrier 27K caused by manufacturing variations. represents.

1.5 Lifespan of Intermediate Transfer Belt 21 FIG. 8 is a diagram showing a state in which dents (carrier dents) are formed on the peripheral surface of the intermediate transfer belt 21 by carriers.

As shown in FIG. 8, the carrier 230 moved from the developer bearing member 27K to the photosensitive drum 23K side is pinched between the peripheral surface of the intermediate transfer belt 21 at the primary transfer position 232, and the carrier 230 is pinched. , dents 231, 232, . . . If the number of dents increases on the peripheral surface of the intermediate transfer belt 21, the toner remains in the dents without being cleaned, resulting in poor cleaning of the peripheral surface of the intermediate transfer belt 21 and the end of the service life of the intermediate transfer belt 21. By estimating the number of dents on the circumferential surface of the intermediate transfer belt 21, the service life of the intermediate transfer belt 21 can be estimated.

FIG. 9 is a graph showing the correspondence relationship between the number of printed sheets (operation amount) and the number of carrier dents.

In the present disclosure, it is determined which curve shown in FIG. 9 is applicable, and the number of printed sheets that will reach the life is estimated.

In FIG. 9, the horizontal axis indicates the number of printed sheets, and the vertical axis indicates the number of dents on the carrier. Curves A2, A1 and B1 respectively correspond to the carrier movement amounts A2, A1 and B1 shown in FIG. 7, and show changes in the number of dents on the carrier as the number of printed sheets increases. In each of the curves A2, A1 and B1, the number of dents on the carrier monotonously increases as the number of printed sheets increases.

Also shown in this figure is a cleaning failure line 251 . If the number of dents on the carrier is generated beyond the cleaning failure line 251, the intermediate transfer belt 21 is determined to be defective in cleaning. In other words, it is determined that the life of the intermediate transfer belt 21 has expired.

The points where the curves A2, A1 and B1 intersect with the cleaning failure line 251 are different. That is, the life of the intermediate transfer belt 21 varies according to the curves A2, A1 and B1. The range of fluctuation of the life is between the number of printed sheets 252 and the number of printed sheets 253 .

When estimating the number of printed sheets to reach the service life, for example, if the state of the intermediate transfer belt 21 corresponds to the curve indicated by B1, the number of printed sheets (253) at the intersection of the curve B1 and the cleaning failure line 251 is taken as the service life. do.

As described above, FIG. 9 shows the second correspondence showing the transition of the number of carrier dents on the circumferential surface of the intermediate transfer belt 21 with respect to the amount of operation according to the movement amount of the carrier caused by manufacturing variations.

In the graph shown in FIG. 9, when a new developer bearing member is attached and the intermediate transfer belt is used, the curve showing the change in the number of carrier dents after that point is plotted on the vertical axis of the graph. The lifetime may be modified by translating in the direction.

1.6 Life of Photoreceptor Drum 23K When the carrier moves to the photoreceptor drum 23K, the carrier adhering to the peripheral surface of the photoreceptor drum 23K is scraped off by the blade 31K (FIG. 2). The blade 31K abrades the peripheral surface (photosensitive film) of the photosensitive drum 23K when scraping off the carrier. When the film thickness of the photoreceptor drum 23K is reduced by a predetermined threshold value or more, the charged charge cannot be maintained, and the life of the photoreceptor drum 23K ends. By estimating wear of the photosensitive film on the peripheral surface of the photosensitive drum 23K, the life of the photosensitive drum 23K can be estimated.

FIG. 10 is a graph showing changes in film thickness of the photosensitive drum 23K.

In the present disclosure, it is determined which curve shown in FIG. 10 corresponds to, and the number of printed sheets (operation amount) that becomes the lifetime is estimated.

In FIG. 10, the horizontal axis indicates the number of printed sheets, and the vertical axis indicates the film thickness of the photosensitive drum 23K. Curves A2, A1 and B1 correspond to carrier movement amounts A2, A1 and B1 shown in FIG. 7, respectively, and show changes in film thickness of the photosensitive drum 23K as the number of printed sheets increases. In each of the curves A2, A1 and B1, the film thickness of the photosensitive drum 23K monotonously decreases as the number of printed sheets increases.

This figure also shows a bad charging line 261 . If the film thickness falls below the charging failure line 261, the photosensitive drum 23K is determined to have charging failure. That is, it is determined that the life of the photosensitive drum 23K has expired.

The points at which the curves A2, A1 and B1 intersect the defective charging line 261 are different. That is, the life of the photosensitive drum 23K varies according to the curves A2, A1 and B1. The fluctuation range of the life is between the number of printed sheets 262 and the number of printed sheets 263 .

When estimating the number of printed sheets to reach the life, for example, if the state of the photosensitive drum 23K corresponds to the curve indicated by B1, the point where the curve B1 and the charging failure line 261 intersect is the life of the number of printed sheets.

As described above, FIG. 10 shows the change in the film thickness of the photoreceptor with respect to the amount of operation of the image forming apparatus 10 according to the amount of movement of the carrier from the developer carrier 27K to the photoreceptor drum 23K due to manufacturing variations. It represents the first correspondence.

1.7 Estimation of Lifespan The procedure described below is performed immediately before or immediately after the image forming apparatus 10 is shipped from the manufacturing factory. The period immediately before shipment from the manufacturing plant or immediately after shipment from the manufacturing plant is called the initial stage.

The test pattern is developed on the peripheral surface of the photosensitive drum 23K by changing the developing bias to be applied with respect to a predetermined test pattern (latent image pattern) so as to take a plurality of values. A test pattern toner image obtained for each bias is transferred onto the circumferential surface of the intermediate transfer belt 21 . Next, the density sensor 42 (FIG. 1) is used to measure the toner densities of the test pattern toner images transferred onto the circumferential surface of the intermediate transfer belt 21 and developed with different developing biases. Next, the developing bias at which a predetermined toner density is obtained is recorded.

If the distance Ds between the peripheral surface of the developer carrier 27K and the peripheral surface of the photosensitive drum 23K becomes closer, a predetermined toner density can be obtained with a lower developing bias.

Moreover, the development bias when a predetermined toner density is obtained is also affected by the environment (temperature).

FIG. 11 is a graph showing the correspondence relationship between the developing bias and the transport amount/Ds corresponding to the case where a predetermined toner density is obtained. In this graph, the horizontal axis indicates the conveying amount/Ds, and the vertical axis indicates the developing bias corresponding to a predetermined toner density.

Also shown in this graph are a curve 272 showing the change in development bias in a low humidity environment and a curve 271 showing the change in development bias in a high humidity environment.

In both cases of curves 272 and 271, the development bias corresponding to the case where a predetermined toner density is obtained monotonically increases as the transport amount/Ds increases.

When the developing bias (C) corresponding to the predetermined toner density is obtained by the measurement by the density sensor 42, using FIG. 11, the transport amount/Ds (D ). Specifically, in FIG. 11, an intersection point 274 where a straight line 273 passing through the point (C) of the obtained developing bias and parallel to the horizontal axis intersects with a curved line 272 is obtained. A straight line 275 parallel to , and an intersection point (D) where the horizontal axis intersects is obtained. The finally obtained intersection point (D) is the transport amount/Ds (D) corresponding to the developing bias.

Here, it is assumed that the humidity measured by the humidity sensor 41 indicates that the image forming apparatus 10 is installed in a low humidity environment.

As described above, FIG. 11 shows the fourth correspondence showing the change in the predetermined developing bias applied to the developer carrier 27K with respect to the transport amount of the developer on the developer carrier 27K caused by manufacturing variations. there is Further, FIG. 11 shows changes in the predetermined developing bias applied to the developer carrier 27K with respect to the transport amount of the developer on the developer carrier 27K caused by manufacturing variations in accordance with environmental information that fluctuates depending on the environment. 5 represents the fifth correspondence shown.

Next, using FIG. 7, the carrier moving amount (E) corresponding to the conveying amount/Ds (D) obtained above is obtained. Specifically, in FIG. 7, an intersection point 214 where a straight line 213 passing through the obtained transport amount/Ds(D) and parallel to the vertical axis and a curved line 212 is obtained. A straight line 215 parallel to , and an intersection point (E) where the horizontal axis intersects is obtained. The finally obtained intersection point (E) is the carrier movement amount (E) corresponding to the transport amount/Ds(D).

Next, using FIG. 9, the life (F) of the intermediate transfer belt 21 corresponding to the obtained carrier movement amount (E) is obtained. Specifically, in FIG. 9, a curve E corresponding to the carrier movement amount (E) is selected, and an intersection point 254 where the selected curve E and the cleaning failure line 251 intersect is obtained. Next, the number of printed sheets (F) at intersection 254 is read. The number of printed sheets (F) thus obtained is the service life (F) of the intermediate transfer belt 21 corresponding to the carrier movement amount (E).

Next, using FIG. 10, the life (G) of the photosensitive drum 23K corresponding to the obtained carrier movement amount (E) is obtained. Specifically, in FIG. 10, a curve E corresponding to the carrier movement amount (E) is selected, and an intersection point 264 where the selected curve E and the charging failure line 261 intersect is obtained. Next, the number of printed sheets (G) at the intersection 264 is read. The number of printed sheets (G) thus obtained is the life (G) of the photosensitive drum 23K corresponding to the carrier movement amount (E).

1.8 Movement of Carrier During Use of Image Forming Apparatus 10 For example, when a trouble such as a recording sheet jam occurs and the printer 12 is stopped urgently, the potential difference between the developing bias and the surface potential of the photosensitive drum 23K is reduced. balance is lost. In such a case, when the potential difference between the two becomes large, a very small amount of carrier moves to the photosensitive drum 23K. When the carrier moves to the photoreceptor drum 23K under such usage conditions, the service life of the photoreceptor drum 23K and the service life of the intermediate transfer belt 21 are corrected.

Specifically, it is as follows.

FIG. 12, like FIG. 9, is a graph showing the correspondence relationship between the number of prints and the number of carrier dents. In this figure, a curve 281 indicates the change in the number of carrier dents estimated at the initial stage, and the number of printed sheets 287 is the number of printed sheets during the lifetime of the intermediate transfer belt 21 estimated at the initial stage.

When a jam occurs in the image forming apparatus 10, at time 282 when the jam occurs, the curve 281 after time 282 is translated in the vertical axis direction of this graph. As a result, curve 281 becomes curve 283 . Furthermore, when a jam occurs, at time 284 when the jam occurs, the curve 283 after time 284 is translated in the vertical axis direction of this graph. As a result, curve 283 becomes curve 285 .

The number of printed sheets at the point where the curve 285 obtained in this manner intersects the line 288 for defective cleaning is the number of sheets for the corrected service life.

In the above description, correction of the service life of the intermediate transfer belt 21 has been described. The life of the drum 23 should be corrected.

The above correction of the service life may be performed when a condition other than the occurrence of a jam occurs when a condition in which the carrier is likely to move occurs. For example, the above-described life span correction may be performed at timings such as when the power of the image forming apparatus is turned on and off, when the potential adjustment of the developing bias is not stable.

1.9 Control circuit 100
As shown in FIG. 3, the control circuit 100 includes a CPU 101, a ROM 102, a RAM 103, an image memory 104, an image processing circuit 105, a network communication circuit 106, a scanner control circuit 107, an input/output circuit 108, a printer control circuit 109, and the like. ing.

The CPU 101, ROM 102 and RAM 103 constitute a main control section 101a.

A RAM 103 temporarily stores various control variables and the number of copies set by the operation panel 19, and provides a work area when the CPU 101 executes a program.

The ROM 102 stores control programs and the like for executing various jobs such as copy operations.

The CPU 101 operates according to control programs stored in the ROM 102 .

By the CPU 101 operating according to the control program, the main control unit 101a unitarily controls the image memory 104, the image processing circuit 105, the network communication circuit 106, the scanner control circuit 107, the input/output circuit 108, the printer control circuit 109, and the like. Control.

Further, the main control unit 101 a receives user's operations from the operation panel 19 . When the user's operation is a print instruction, the main control unit 101a causes the printer control circuit 109 to execute image forming processing. If the user's operation is another instruction, the main control unit 101a causes other processing to be executed. For example, the main control unit 101a receives, from the operation panel 19, setting completion information indicating that a new developer carrier has been set by the manufacturer. Upon receiving the set completion information, the main control unit 101a outputs the set completion information to the life acquisition circuit 112 via the printer main control circuit 111, which will be described later.

The image memory 104 temporarily stores image data such as print jobs.

For example, the image processing circuit 105 performs various data processing on the image data of each color component of R, G, and B obtained by the image reader 11 to obtain each reproduction color of Y, M, C, and K. Convert to image data.

A network communication circuit 106 receives a print job from an external terminal device such as a PC (personal computer) via a network such as a LAN.

The scanner control circuit 107 controls the image reader 11 to read the image of the document.

The printer control circuit 109 will be described next.

1.10 Printer control circuit 109
The printer control circuit 109 includes a printer main control circuit 111, a life acquisition circuit 112, a storage circuit 113, and the like, as shown in FIG.

(1) Printer main control circuit 111
The printer main control circuit 111 uniformly controls the feeding operation from the paper feeding unit 13 and the image forming operations of the image forming units 20Y to 20K of the printer 12, and causes the image forming operation to be executed.

Further, the printer main control circuit 111 controls the lifespan acquisition circuit 112 to perform processing for lifespan acquisition.

The printer main control circuit 111 determines whether or not there is a usage condition in which the carrier moves from the developer carrier 27K to the photosensitive drum 23K. For example, it is determined whether or not an event has occurred that causes the operation of the printer 12 to stop urgently due to a recording sheet jam or the like. When it is determined that there is a usage situation in which the carrier moves, the printer main control circuit 111 outputs an emergency stop signal to the life acquisition circuit 112 to correct the lives of the intermediate transfer belt 21 and the photosensitive drum 23K. Let

Further, the printer main control circuit 111 determines whether or not the intermediate transfer belt 21 or the photoreceptor drum 23K has reached the end of its life. When it is determined that the intermediate transfer belt 21 or the photoreceptor drum 23K has reached the end of its life, the printer main control circuit 111 notifies the operation panel 19 via the main control unit 101a and the input/output circuit 108 that the intermediate transfer belt 21 or the photoreceptor drum 23K is output.

(2) Memory circuit 113
The storage circuit 113 (storage means) is composed of, for example, a nonvolatile semiconductor memory or the like. Of course, the storage circuit 113 may be configured with a hard disk.

The memory circuit 113 has an area for storing the life of the intermediate transfer belt 21 and the life of the photosensitive drum 23K.

The storage circuit 113 also has a data table in which curves and straight lines indicating respective changes in the graphs shown in FIGS. 7, 9, 10 and 11 are stored in advance as data. Note that the storage circuit 113 may store, in advance, curves and straight lines indicating changes in the graphs shown in FIGS. 7, 9, 10, and 11 as functions.

That is, the storage circuit 113 stores in advance the first correspondence, the second correspondence, the third correspondence, the fourth correspondence, and the fifth correspondence.

(3) life acquisition circuit 112
The lifespan acquisition circuit 112 receives set completion information from the main control unit 101a via the printer main control circuit 111. FIG. Further, when the printer main control circuit 111 determines that there is a usage situation in which the carrier moves from the developer carrier 27K to the photosensitive drum 23K, the lifespan acquisition circuit 112 receives an urgent request from the printer main control circuit 111. Receive a stop signal.

(a) Upon receiving the set completion information, the lifespan acquisition circuit 112 (development bias acquisition means, sub-estimation means) causes the printer main control circuit 111 to form a toner image of a predetermined test pattern, and the toner density is calculated. By executing the measurement, the development bias (C) when a predetermined toner density is obtained is obtained.

Also, the lifespan obtaining circuit 112 (environmental information obtaining means, sub-estimating means) obtains humidity (environmental information) from the humidity sensor 41 .

Furthermore, the lifespan obtaining circuit 112 estimates the lifespan of the intermediate transfer belt 21 and the photosensitive drum 23K according to the procedures (a-1) to (a-4) shown below. In the following procedures (a-1) to (a-4), calculations are performed using data tables corresponding to each graph. In addition, it is not limited to this. A function stored in the storage circuit 113 and corresponding to each graph may be used to perform an operation.

(a-1) The life acquisition circuit 112 (conveyance amount acquisition means, sub-estimation means) obtains the conveyance amount/Ds (D) corresponding to the acquired development bias (C) using FIG.

FIG. 11 is a graph showing the correspondence relationship between the developing bias and the transport amount/Ds corresponding to the case where a predetermined toner density is obtained.

The lifespan acquisition circuit 112 reads a data table corresponding to the graph shown in FIG. 11 from the storage circuit 113 .

Next, the life acquisition circuit 112 uses the read data table to obtain a straight line 273 passing through the obtained development bias point (C) and parallel to the horizontal axis, and a curved line 272 in the graph shown in FIG. A calculation is performed to obtain an intersection point 274 where .DELTA. The finally obtained intersection point (D) is the transport amount/Ds (D) corresponding to the developing bias.

(a-2) Next, the lifetime obtaining circuit 112 (estimating means) uses FIG. 7 to obtain the carrier movement amount (E) corresponding to the obtained transport amount/Ds (D).

FIG. 7 is a graph showing the correspondence relationship between the transport amount/Ds and the amount of movement of the carrier from the developer carrier 27K.

The lifespan obtaining circuit 112 reads a data table corresponding to the graph shown in FIG. 7 from the storage circuit 113 .

Next, using the read data table, the life acquisition circuit 112 uses the graph shown in FIG. , and from the intersection point 214, a straight line 215 parallel to the horizontal axis and an intersection point (E) where the horizontal axis intersects is calculated. The finally obtained intersection point (E) is the carrier movement amount (E) corresponding to the transport amount/Ds(D).

(a-3) Next, the life acquisition circuit 112 (acquisition means) uses FIG. 9 to obtain the life (F) of the intermediate transfer belt 21 corresponding to the carrier movement amount (E).

FIG. 9 is a graph showing the correspondence relationship between the number of prints and the number of carrier dents.

The lifespan obtaining circuit 112 reads a data table corresponding to the graph shown in FIG. 9 from the storage circuit 113 .

Next, the life acquisition circuit 112 uses the read data table to perform an operation to select a curve E corresponding to the obtained carrier movement amount (E) in the graph shown in FIG. , and an intersection point 254 where the cleaning failure line 251 intersects. Next, life acquisition circuit 112 reads the number of prints (F) at intersection 254 . The number of printed sheets (F) thus obtained is the service life (F) of the intermediate transfer belt 21 corresponding to the carrier movement amount (E).

(a-4) Next, the life obtaining circuit 112 (obtaining means) uses FIG. 10 to obtain the life (G) of the photosensitive drum 23K corresponding to the carrier movement amount (E).

FIG. 10 is a graph showing the correspondence relationship between the number of prints and the film thickness of the photosensitive drum 23K.

Lifespan acquisition circuit 112 reads a data table corresponding to the graph shown in FIG. 10 from storage circuit 113 .

Next, the life acquisition circuit 112 uses the read data table to perform an operation to select a curve E corresponding to the obtained carrier movement amount (E) in the graph shown in FIG. , an intersection point 264 at which the charging failure line 261 intersects. Next, the life acquisition circuit 112 reads the number of prints (G) at the intersection point 264 . The number of printed sheets (G) thus obtained is the life (G) of the photosensitive drum 23K corresponding to the carrier movement amount (E).

(b) Upon receiving the emergency stop signal, the life acquisition circuit 112 (correcting means) corrects the lives of the intermediate transfer belt 21 and the photosensitive drum 23K.

Specifically, with respect to the intermediate transfer belt 21, the life acquisition circuit 112, in the curve showing the change in the number of carrier dents shown in FIG. Calculation to translate is performed. Similar calculations are performed for the photosensitive drum 23K.

In this manner, the life acquisition circuit 112 may correct the acquired life of the photoreceptor drum 23K according to the usage status of the photoreceptor drum 23K. Here, the lifespan acquisition circuit 112 may correct a jam of a recording sheet.

Further, the life acquisition circuit 112 may correct the acquired life of the intermediate transfer belt 21 according to the usage status of the intermediate transfer belt 21 . Here, the lifespan acquisition circuit 112 may correct a jam of a recording sheet.

1.11 Operation of Image Forming Apparatus 10 Operation of the image forming apparatus 10 regarding the life of the intermediate transfer belt 21 and the photosensitive drum 23K will be described.

(1) Operations related to life estimation and replacement of the intermediate transfer belt 21 and the photosensitive drum 23K will be described with reference to the flowchart shown in FIG.

The main control unit 101a receives setting completion information indicating that a new developer carrier has been set by the manufacturer from the operation panel 19 (step S101).

The lifespan obtaining circuit 112 causes the printer main control circuit 111 to read the initial density, and obtains the humidity from the humidity sensor as environment information (step S102).

Next, the service life acquisition circuit 112 estimates the service life of the intermediate transfer belt 21 and the photosensitive drum 23K (step S103).

The printer main control circuit 111 determines whether or not there is a usage condition in which the carrier moves from the developer carrier 27K to the photosensitive drum 23K (step S104).

When it is determined that there is a usage situation in which the carrier moves ("YES" in step S104), the life acquisition circuit 112 corrects the life of the intermediate transfer belt 21 and the photosensitive drum 23K (step S105).

The printer main control circuit 111 determines whether or not the intermediate transfer belt 21 or the photosensitive drum 23K has reached the number of sheets in its life (step S106).

If it is determined that the intermediate transfer belt 21 or the photoreceptor drum 23K has not reached the end of its life (“NO” in step S106), the printer main control circuit 111 shifts the control to S104 and continues the process.

If it is determined that the intermediate transfer belt 21 or the photosensitive drum 23K has reached the end of its life (“YES” in step S106), the printer main control circuit 111, via the main control unit 101a and the input/output circuit 108, A request to replace the intermediate transfer belt 21 or the photosensitive drum 23K is output to the operation panel 19, and the operation panel 19 displays the request to replace the intermediate transfer belt 21 or the photosensitive drum 23K (S107).

This concludes the description of the operation of estimating the service life of the intermediate transfer belt 21 and the photosensitive drum 23K and replacing them.

(2) Life Estimation Operation of Intermediate Transfer Belt and Photoconductor Drum The operation of estimating the life of the intermediate transfer belt and photoconductor drum will be described with reference to the flowchart shown in FIG.

The life acquisition circuit 112 uses FIG. 11 to obtain the transport amount/Ds (D) corresponding to the developing bias (C) (step S131).

Next, the life acquisition circuit 112 obtains the carrier movement amount (E) corresponding to the conveyance amount/Ds (D) using FIG. 7 (step S132).

Next, the lifespan acquisition circuit 112 obtains the lifespan (F) of the intermediate transfer belt 21 corresponding to the carrier movement amount (E) using FIG. 9 (step S133).

Next, the life acquisition circuit 112 obtains the life (G) of the photosensitive drum 23K corresponding to the carrier movement amount (E) using FIG. 10 (step S134).

As described above, the service life of the intermediate transfer belt 21 and the service life of the photosensitive drum 23K can be estimated.

1.12 Summary As described above, an image forming apparatus that develops an electrostatic latent image on the surface of a photoreceptor drum with toner transported by a developer carrier that carries a developer containing toner and carrier may be affected by manufacturing variations. In accordance with the amount of movement of the carrier from the developer bearing member to the photosensitive drum, a first correspondence relationship showing the change in film thickness of the photosensitive member with respect to the amount of operation of the image forming apparatus is stored. In the initial stage of , the amount of movement of the carrier is estimated, the first correspondence is referenced based on the amount of movement of the carrier obtained by estimation, and the number of printed sheets (operation amount) corresponding to the film thickness reaching the end of life is calculated as the photoreceptor. It may be acquired as the lifetime of the drum.

The image forming apparatus may also include an intermediate transfer belt onto which a toner image formed by developing an electrostatic latent image is transferred. A portion of the carrier that has moved to the photosensitive drum creates dents on the peripheral surface of the intermediate transfer belt. The image forming apparatus stores a second correspondence showing the transition of the number of dents of the carrier on the circumferential surface of the intermediate transfer belt with respect to the amount of operation, according to the amount of movement of the carrier caused by manufacturing variations, and is obtained by estimation. The second correspondence may be referred to based on the obtained carrier movement amount, and the operation amount corresponding to the number of dents reaching the end of the life may be acquired as the life of the intermediate transfer belt member.

Further, the image forming apparatus stores a third correspondence relationship indicating a change in the amount of movement of the carrier from the developer carrier to the photosensitive drum with respect to the transport amount of the developer on the developer carrier due to manufacturing variations. In this case, the transport amount of the developer transported by the developer carrying member may be estimated, the third correspondence may be referred to, and the movement amount of the carrier corresponding to the transport amount of the developer obtained by the estimation may be obtained. .

Further, the image forming apparatus stores a fourth correspondence relationship indicating a change in the predetermined developing bias applied to the developer carrier with respect to the transport amount of the developer on the developer carrier caused by manufacturing variations. By switching the developing bias applied to the developer carrying member, the density of the toner image formed on the photoreceptor is varied. In the initial stage, the image forming apparatus develops an electrostatic latent image having a predetermined pattern, obtains a developing bias that provides a predetermined toner density, refers to the fourth correspondence relationship, and corresponds to the obtained developing bias. The conveyed amount of the developer may be obtained.

In addition, the image forming apparatus indicates the change in the predetermined developing bias applied to the developer carrier with respect to the amount of developer transported on the developer carrier due to manufacturing variations, according to the environmental information that fluctuates depending on the environment. A fifth correspondence is stored. By switching the developing bias applied to the developer bearing member, the density of the toner image formed on the photosensitive drum is varied. The image forming apparatus acquires environmental information, develops an electrostatic latent image having a predetermined pattern in the initial stage, obtains a developing bias that provides a predetermined toner density, and performs a fifth response according to the acquired environmental information. By referring to the relationship, the transport amount of the developer corresponding to the obtained developing bias may be obtained.

As described above, the image forming apparatus has an excellent effect of being able to predict the service life of the intermediate transfer belt 21 and the photoreceptor drum 23K provided in the image forming apparatus even when there are variations in manufacturing.

2 Other Modifications Although the present disclosure has been described based on the above embodiments, it is not limited to the embodiments. You may make it show below.

(1) In the above embodiment, the image forming apparatus 10 includes the intermediate transfer belt 21, but is not limited to this.

The image forming apparatus may employ a direct transfer method in which the toner image is directly transferred from the photosensitive drum to the recording sheet without an intermediate transfer belt.

(2) In the above embodiment, when it is determined that the number of sheets of the intermediate transfer belt 21 or the photoreceptor drum 23K has reached the end of its service life, the operation panel 19 requests replacement of the intermediate transfer belt 21 or the photoreceptor drum 23K. it's shown. However, it is not limited to this.

For example, when it is determined that the number of printed sheets on the intermediate transfer belt 21 or the photosensitive drum 23K has reached 90% of the life, the operation panel 19 prepares to replace the intermediate transfer belt 21 or the photosensitive drum 23K. A message to that effect (to the effect that the replacement time is approaching) may be displayed.

(3) As described above, the image forming apparatus is a computer system with a microprocessor and memory. The memory stores computer programs, and the microprocessor may operate according to the computer programs.

A microprocessor consists of a fetch section, a decode section, an execution section, a register file, an instruction counter, and so on. The fetch unit reads each instruction code included in the computer program one by one from the computer program stored in the memory. The decoding unit decodes the read instruction code. The execution part operates according to the decoding result. Thus, the microprocessor operates according to computer programs stored in memory.

Here, the computer program is constructed by combining a plurality of instruction codes indicating instructions to the computer in order to achieve a predetermined function.

Also, the computer program may be recorded on a computer-readable recording medium such as a flexible disk, hard disk, optical disk, or semiconductor memory.

Also, the computer program may be transmitted via a wired or wireless telecommunication line, a network represented by the Internet, data broadcasting, or the like.

(4) The above embodiments and modifications may be combined.

The image forming apparatus according to the present disclosure has the excellent effect of being able to predict the service life of the photoreceptor included in the individual image forming apparatus even when there is variation during manufacturing. It is useful as a technique for forming an image by an electrophotographic method using a system developer.

10 image forming apparatus 11 image reader 12 printer 13 paper feeding section 14 image forming unit 15 discharge tray 19 operation panel 20Y to 20K image forming section 21 intermediate transfer belt 22 secondary transfer roller 23K photoreceptor drum 24K charging charger 25K LED array 26K developing Device 27K Developer carrier 28K Primary transfer roller 29K Gap 30K Development position 31K Blade 32K Regulating member 41 Humidity sensor 42 Density sensor 50 Fixing unit 51 Heating roller 52 Pressure roller 60-62 Paper feed cassette 63-65 Pick-up roller 100 Control circuit 101 CPUs
101a main control unit 102 ROM
103 RAM
104 image memory 105 image processing circuit 106 network communication circuit 107 scanner control circuit 108 input/output circuit 109 printer control circuit 111 printer main control circuit 112 life acquisition circuit 113 storage circuit

Claims (10)

An image forming apparatus that develops an electrostatic latent image on a surface of a photoreceptor with toner carried by a developer carrying member that carries a developer containing toner and carrier,
A memory that stores a first correspondence showing a change in film thickness of the photoreceptor with respect to the amount of operation of the image forming apparatus according to the amount of movement of the carrier from the developer bearing member to the photoreceptor due to manufacturing variations. means and
estimating means for estimating a movement amount of the carrier in an initial stage of use of the image forming apparatus;
obtaining means for obtaining, as the life of the photoreceptor, the amount of operation corresponding to the film thickness reaching the end of the life by referring to the first correspondence based on the movement amount of the carrier obtained by the estimation; image forming device. further comprising an intermediate transfer member onto which a toner image formed by developing the electrostatic latent image is transferred;
part of the carrier that has moved to the photoreceptor forms a dent on the peripheral surface of the intermediate transfer member;
The storage means further stores a second correspondence showing transition of the number of dents of the carrier on the peripheral surface of the intermediate transfer member with respect to the amount of operation according to the amount of movement of the carrier caused by the manufacturing variation,
The acquiring means further refers to the second correspondence relationship based on the movement amount of the carrier obtained by the estimation, and acquires the operation amount corresponding to the number of dents reaching the end of the life as the life of the intermediate transfer member. 2. The image forming apparatus according to claim 1, wherein: The storage means further stores a third correspondence relationship indicating a change in the amount of carrier movement from the developer carrier to the photoreceptor with respect to the transport amount of the developer on the developer carrier due to manufacturing variations. and
The estimation means is
a sub-estimating means for estimating the transport amount of the developer transported by the developer carrier in the initial stage;
3. The image according to claim 1, further comprising a movement amount acquisition unit that refers to the third correspondence relationship and acquires a movement amount of the carrier corresponding to the transport amount of the developer obtained by the estimation. forming device. The storage means further stores a fourth correspondence relationship indicating a change in the predetermined developing bias applied to the developer carrier with respect to the transport amount of the developer on the developer carrier caused by manufacturing variations. cage,
By switching the developing bias applied to the developer bearing member, the density of the toner image formed on the photoreceptor varies,
The secondary estimation means is
developing bias acquisition means for developing an electrostatic latent image having a predetermined pattern in the initial stage and obtaining a developing bias that provides a predetermined toner density;
4. The image forming apparatus according to claim 3, further comprising conveying amount obtaining means for obtaining a conveying amount of the developer corresponding to the obtained developing bias by referring to the fourth correspondence. Further, the storage means changes the predetermined developing bias applied to the developer carrier with respect to the amount of developer transported on the developer carrier due to manufacturing variations in accordance with environmental information that varies depending on the environment. and stores a fifth correspondence relationship indicating
By switching the developing bias applied to the developer bearing member, the density of the toner image formed on the photoreceptor varies,
The secondary estimation means is
environmental information acquisition means for acquiring environmental information;
developing bias acquisition means for developing an electrostatic latent image having a predetermined pattern in the initial stage and obtaining a developing bias that provides a predetermined toner density;
4. The apparatus according to claim 3, further comprising a conveying amount acquiring unit that acquires a conveying amount of the developer corresponding to the obtained developing bias by referring to a fifth correspondence relationship according to the acquired environmental information. image forming device. 2. The image forming apparatus according to claim 1, further comprising a correcting unit that corrects the acquired life of the photoreceptor in accordance with usage conditions of the photoreceptor. 7. The image forming apparatus according to claim 6, wherein the correcting means corrects when a recording sheet jam occurs. 3. The image forming apparatus according to claim 2, further comprising correcting means for correcting the acquired life span of the intermediate transfer member according to the usage status of the intermediate transfer member. 9. The image forming apparatus according to claim 8, wherein the correcting means corrects when a recording sheet jam occurs. A control method used in an image forming apparatus that develops an electrostatic latent image on a surface of a photoreceptor with toner conveyed from a developer carrying member that carries a developer composed of toner and carrier, comprising:
The image forming apparatus stores a first correspondence showing a change in the film thickness of the photoreceptor with respect to the amount of operation of the image forming apparatus, according to the amount of movement of the carrier to the photoreceptor due to manufacturing variations,
The control method is
an estimating step of estimating an amount of carrier movement from the developer bearing member to the photoreceptor in an initial stage of use of the image forming apparatus;
an acquisition step of referring to a first correspondence relationship based on the movement amount of the carriers obtained by the estimation, and acquiring the operation amount corresponding to the film thickness reaching the end of the life as the life of the photoreceptor. control method.

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