JP2018040981A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus which can perform service life management of a photoreceptor by torque measurement for each photoreceptor while being in a type of rotationally driving the plurality of photoreceptors carrying toner images by a common drive source.SOLUTION: An image forming apparatus includes a plurality of photoreceptors, a stationary type cleaning member is provided in each of the plurality of photoreceptors, and the photoreceptors of a plurality of image forming units are collectively rotationally driven by a common drive source. The image forming apparatus acquires a first torque value being a drive torque value of the common drive source in such a state that toner is not applied to each of the plurality of photoreceptors at the time of deterioration determination, acquires a second torque value being the drive torque value of the common drive source in such a state that toner is applied to any one of the plurality of photoreceptors, determines that the photoreceptor applied with toner has not been deteriorated yet if the torque difference (Ye, Me, Ce) being the difference between the first torque value and the second torque value is small, and determines that the photoreceptor has been deteriorated if the torque difference is large.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an image forming apparatus that forms an image on a medium using toner. More specifically, the present invention relates to an image forming apparatus that includes a plurality of photoconductors that carry toner images and that is configured to rotate the plurality of photoconductors with a single drive source.

  Conventionally, an image forming apparatus using toner has used a photoreceptor. That is, an electrostatic latent image is formed on the surface of the photoconductor, and toner is formed by supplying toner thereto. The toner image is transferred to the medium, whereby an image is formed on the medium. The surface of the photoreceptor is worn with use and eventually reaches the end of its life. A simple method for managing the life of the photoconductor is the integration of the number of image formations. However, the progress of the life of the photoreceptor is not simply proportional to the number of images formed. It also depends on the toner coverage in the image to be formed. This is because the toner effectively acts as a lubricant to delay the abrasion of the photoreceptor. For this reason, if the limit value of the cumulative number of images formed is set to be safer, an event may occur in which a photoconductor that has not actually reached the end of its life is actually replaced. This is a case where many images with a high toner coverage are formed. This is not preferable from the viewpoint of effective use of resources.

  Therefore, in the image forming apparatus disclosed in Patent Document 1, the life of the photosensitive member (electrophotographic photosensitive member) is managed by an index other than the number of images formed. Specifically, the driving torque when rotating the photosensitive member is measured. Furthermore, a heater for adjusting the temperature of the photoreceptor is provided. Thus, the life of the photoconductor is determined based on the change in driving torque when the temperature of the photoconductor is changed.

JP 2014-002233 A

  However, the conventional image forming apparatus described above has the following problems. Application to a color image forming apparatus is not always easy. In particular, among color image forming apparatuses, it is a tandem type color image forming apparatus having a photoconductor for each color, and it is difficult to apply to a type in which a plurality of photoconductors are driven by a common motor. . Since the measured drive torque is for driving a plurality of photoconductors simultaneously, the life of each photoconductor could not be determined.

  The present invention has been made to solve the problems of the conventional image forming apparatus described above. That is, the problem is that a plurality of photoconductors carrying toner images are rotationally driven by a common drive source, and life management of the photoconductors by torque measurement can be individually performed for each photoconductor. An object of the present invention is to provide an image forming apparatus capable of performing the above.

  An image forming apparatus according to an aspect of the present invention includes a plurality of image forming units, and each of the plurality of image forming units includes a photosensitive member, a developing device that applies toner to the photosensitive member, and a toner on the photosensitive member. An apparatus for forming an image on a medium by transferring toner onto the medium before being removed by the cleaning member from the developing unit. , A common drive source that rotationally drives the photosensitive members of the plurality of image forming units, a torque measuring unit that outputs an index value of torque when the common drive source is rotated, and a plurality of image forming units that are not used during image formation. A deterioration determination unit that individually determines the deterioration state of the photoconductor, and the deterioration determination unit drives the common drive source without applying toner to any of the photoconductors of the plurality of image forming units. A first torque value that is an output value of the torque measurement unit at the time when the common drive source is driven in a state where toner is applied to any one of the plurality of image forming units. When the second torque value that is the output value of the second torque value is acquired and the torque difference that is the difference obtained by subtracting the second torque value from the first torque value is not large enough to correspond to the predetermined deterioration determination event, When it is determined that the photoreceptor to which toner is applied at the time of obtaining the torque value has not yet deteriorated, and the torque difference is large enough to correspond to a deterioration determination event, the photoreceptor to which toner has been applied at the time of obtaining the second torque value It is comprised so that it may determine with having deteriorated.

  In the image forming apparatus according to the above aspect, the deterioration determination is performed while driving the common drive source. Therefore, the deterioration determination is performed in a state where all the photoconductors driven by the common drive source are also rotating. In the deterioration determination, the first torque value and the second torque value are acquired. The first torque value is a torque value when no toner is applied to any of the plurality of photoconductors. The second torque value is a torque value in a state where toner is applied to any one of the plurality of photoconductors. A torque difference that is a difference between the first torque value and the second torque value is an index value of the deterioration state of the photoreceptor to which the toner is applied. Therefore, if the torque difference is not so large as to correspond to a predetermined deterioration determination event, it is determined that the photoconductor has not deteriorated yet. On the other hand, if the torque difference is large enough to correspond to a deterioration determination event, it is determined that the photoconductor has deteriorated. This determination is independent of the deterioration state of other photoconductors driven by the common drive source.

  The image forming apparatus of the above aspect further includes an initial state storage unit that stores an initial difference, which is a torque difference when any of the photosensitive members of the plurality of image forming units is in an initial state, for each of the plurality of photosensitive members. The determination unit acquires the first torque value and the second torque value for each of the plurality of photoconductors after the start of use, and determines the post-use difference, which is a torque difference after the start of use, as an initial difference for each of the plurality of photoconductors. You may be comprised so that it may contrast. In this case, the deterioration determination event for the photoconductor is that the increment obtained by subtracting the initial difference from the post-use difference is larger than a predetermined limit value. In this way, a more appropriate deterioration determination can be made based on the initial state of each photoconductor.

  In the image forming apparatus of the above aspect, the deterioration determination unit applies toner to the photosensitive member of the image forming unit when the second torque value is acquired, and the toner is removed by the cleaning member of the image forming unit. It is preferable to perform the entire range in the width direction. As a result, even when papers of various sizes are used and the deterioration state is uneven depending on the position in the width direction, deterioration determination corresponding to the deterioration state of the entire width direction range is made.

  In the image forming apparatus of the above aspect, the image forming apparatus includes an image formation amount integration unit that integrates the cumulative execution amount of image formation from the initial state, and the deterioration determination unit determines that the integrated value of the cumulative execution amount reaches a predetermined default value. After that, it is preferable to determine the deterioration state of the photoconductor. In the image forming apparatus according to the aspect described above, when the deterioration determination unit determines that no photoconductor is deteriorated by determining the deterioration state of the photoconductor, The interval until the determination is performed may be set short. As a result, it is possible to reliably perform the deterioration determination when the life of the photoconductor is approaching, while suppressing the toner consumption due to the deterioration determination.

  In the image forming apparatus of the above aspect, with respect to the output value of the environment detection unit that acquires at least one of temperature and humidity, and the torque measurement unit, the temperature is reduced as the temperature is higher, and the temperature is emphasized as the temperature is lower. And an environmental correction unit that performs at least one of correction and a humidity correction that emphasizes the value as the humidity increases and reduces the value as the humidity decreases, and the deterioration determination unit receives the correction performed by the environmental correction unit. It is also preferable that the deterioration state of the photosensitive member is determined using the first torque value and the second torque value. Although the rotation resistance of the common drive source depends on environmental factors, such a correction function makes it possible to make an appropriate deterioration determination according to the environmental factors.

  According to this configuration, a plurality of photoconductors that carry toner images are rotationally driven by a common drive source, and the life of the photoconductor can be individually managed for each photoconductor by torque measurement. A forming apparatus is provided.

1 is a cross-sectional view illustrating a main part of an image forming apparatus according to an embodiment. FIG. 3 is a schematic diagram illustrating a configuration of a driving system of a photosensitive member in the embodiment. 2 is a block diagram illustrating a configuration of a control system of the image forming apparatus according to the embodiment. FIG. It is a graph which shows the fluctuation | variation of the drive torque of a photoreceptor. FIG. 6 is a perspective view illustrating a relationship between a toner supply width and a cleaning width by a cleaning blade. It is a graph which shows the change of the electric current value at the time of deterioration determination. It is a graph which shows the change of the electric current value at the time of performing deterioration determination at the time of a new article.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the accompanying drawings. In this embodiment, an image forming apparatus 1 whose main part is shown in FIG. 1 has an image forming unit 2 and a paper feeding unit 3. The image forming unit 2 includes an intermediate transfer belt 4 and photoreceptor units 5Y (yellow), 5M (magenta), 5C (cyan), and 5K (black). The image forming unit 2 is further provided with a secondary transfer roller 6 and a fixing device 7. As a result, a four-color full-color toner image is formed on the paper supplied from the paper supply unit 3.

  The photoconductor unit 5Y includes a photoconductor 8, a charger 9, an exposure device 10, a developing device 11, a primary transfer roller 12, and a cleaner box 13. The cleaner box 13 is provided with a cleaning blade 14. The cleaning blade 14 is pressed against the photoconductor 8 in a stationary state. The residual toner on the photosensitive member 8 is removed by the cleaning blade 14. The photoconductor units 5M and 5C have the same configuration as the photoconductor unit 5Y. The photoconductor unit 5K also basically has the same configuration as the photoconductor units 5Y, 5M, and 5C, although each component is slightly larger.

  In the image forming apparatus 1 of this embodiment, a drive system for four photosensitive members 8 is configured as shown in FIG. The image forming apparatus 1 is provided with two motors for driving the photoreceptor 8. A color motor 15 and a black motor 16. The color motor 15 is a common drive source for the three photoreceptors 8 for Y color, M color, and C color, and the black motor 16 is a single drive source for the K color photoreceptor 8. For this reason, the three photoreceptors 8 for Y color, M color, and C color rotate together when rotating, and all stop when stopped.

  The configuration of the control system of the image forming apparatus 1 of this embodiment is shown in FIG. The control system in FIG. 3 is configured around the control unit 17. The control unit 17 operates by receiving power supply from a low-voltage power source (power source by step-down from a commercial power source) 18. The control unit 17 incorporates various control circuits, and a main circuit is a drive circuit 19. The drive circuit 19 controls the rotation of the color motor 15 and the black motor 16. The drive circuit 19 further has a function of detecting current when the color motor 15 and the black motor 16 are driven, which will be described later. This is essentially a function that measures the torque required during motor rotation. This function is used for life management of the photoconductor 8.

  The control unit 17 is further connected to a high voltage power source (power source by boosting from a commercial power source) 20, each sensor 21, and a notification unit 22. The high-voltage power supply 20 controls process voltages such as development and transfer. Each sensor 21 includes an internal environmental condition (temperature, humidity) sensor, a paper out sensor of the paper feed unit 3, and the like. The notification unit 22 transmits (by display or voice) various messages to the user.

  The characteristic point of the image forming apparatus 1 of the present embodiment configured as described above is in the life management of the photoconductors 8, particularly the three photoconductors 8 (Y, M, C) for color. Therefore, this life management will be described. In this embodiment, the end of the life of the photoconductor 8 is determined by detecting the torque necessary for driving the photoconductor 8. The photoreceptor 8 has a property that the torque required for driving increases as the deterioration due to endurance use proceeds. This is because the surface of the photoconductor 8 is roughened with wear due to use.

This will be described with reference to the graph of FIG. The horizontal axis of the graph of FIG. 4 is the number of durable images formed, and the vertical axis is the current value required to rotate the color motor 15 at the speed at the time of image formation. This current value is an index value of the torque required to rotate the three photoconductors 8 (Y, M, C) at the speed at the time of image formation. Further, in FIG. 4, four graphs (a) to (d) are drawn. The meaning is as follows.
(A) Current values when no toner is supplied for all three colors.
(B) A current value in a state where toner is supplied only for C color.
(C) Current value in a state where toner is supplied only for Y color.
(D) Current value in a state where toner is supplied only for M color.

  Here, “supplying toner” in the above (b) to (d) refers to a state of so-called solid printing in the width direction. That is, the toner is supplied to the entire image forming width. In this state, as shown in FIG. 5, the toner is supplied to the entire cleaning width that is the width at which the cleaning blade 14 contacts the photoconductor 8. In any of the above (b) to (d), the bias voltage of the primary transfer roller 12 is turned off, although it is different from the original image forming state. That is, the toner supplied from the developing unit 11 to the photoconductor 8 reaches the cleaning blade 14 in its entirety.

  Referring to FIG. 4, (a) is the highest position among the four graphs, and (b) to (d) are all below (a). This means that the rotational resistance of the photoconductor 8 is high when no toner is supplied for all three colors, and the rotational resistance is lowered when the toner is supplied. This is because the frictional resistance of the cleaning blade 14 occupying a considerable portion of the rotational resistance of the photoconductor 8 is reduced by the actual lubricating action of the toner. Note that the order of (b), (c), and (d) shown in FIG. 4 is merely an example, and this order is not necessarily true. If the body of the image forming apparatus 1 is different, the order may be different. It also depends on the content of the image to be formed.

  In FIG. 4, the four graphs as a whole have an upward slope. This means that the drive torque increases with the progress of endurance use. This corresponds to an increase in rotational resistance (particularly, contact resistance by the cleaning blade 14) as the surface of the photoconductor 8 becomes rough. However, in the period immediately after the start of use at the left end in FIG. 4 (symbol R), on the contrary, all the four graphs are lowered to the right. This is a resistance reduction phenomenon due to the initial running-in of the drive transmission mechanism from the color motor 15 to the photosensitive member 8. Since this phenomenon is not the subject of attention in the present invention, it is basically ignored for the present invention. In FIG. 4, the graph has already changed considerably from the lower right to the upper right at about 300,000 sheets in the middle of durable use. In the vicinity of about 320,000 sheets, the initial (0) current value is clearly exceeded.

  Further, in FIG. 4, the difference (torque difference) between the highest graph (a) and the lower graphs (b) to (d) also tends to increase with the progress of endurance use. This means that the difference in rotational resistance of the photosensitive member 8 between when no toner is supplied and when the toner is supplied is small at a relatively early stage of durable use. This is because, at the initial stage, the surface of the photoconductor 8 has a high smoothness and the contact resistance by the cleaning blade 14 is originally low, so even if toner is supplied thereto, the amount of decrease in rotational resistance is small. On the other hand, as the durable use progresses, the surface of the photoconductor 8 is roughened, and the contact resistance by the cleaning blade 14 is increased, so that the reduction in rotational resistance due to toner supply is also large.

  In the image forming apparatus 1 of this embodiment, the deterioration determination of the photoconductor 8 is performed at appropriate intervals after the start of use. This deterioration determination is performed by performing the following at a time other than the time of image formation. That is, the drive current value is monitored while the color motor 15 is rotated at the same speed as that during image formation. Then, Y, M, and C toners are sequentially supplied. However, at that time, toner of more than two colors is not supplied at the same time. There is also a period in which no toner is supplied.

  FIG. 6 shows a profile of the drive current value of the color motor 15 obtained in this way. This graph shows the measured current value, and the direction from left to right corresponds to the passage of time. FIG. 6 shows an example of the result when the durable use is 340,000 sheets. As shown in FIG. 6, the current value decreases three times. The current value at a constant current other than the current drop is the index value (first torque value) of the driving torque in the toner non-supply state (the above-mentioned (a)).

  The first (left) of the three current value drops in FIG. 6 is due to the supply of Y color toner. Accordingly, the current value at the bottom at this time is an index value of the driving torque (second torque value for Y color) in the Y color toner supply state (the above-mentioned (c)). Similarly, the bottom current value in the second (middle) current value drop is the index value of the driving torque (second torque value for M color) in the M color toner supply state (described above (d)). . The bottom current value at the last (right) current value drop is the index value (second torque value for C color) of the drive torque in the C color toner supply state (described above (b)). Strictly speaking, it is necessary to convert the current value to the torque value, but a conversion table for that purpose may be prepared in advance.

  Therefore, for each color, the difference between the first torque value and the second torque value, that is, the torque difference is calculated. In FIG. 6, Ye, Me, and Ce correspond to the torque differences for the colors Y, M, and C, respectively. From the above, the torque differences Ye, Me, and Ce are index values indicating the degree of deterioration (surface wear) of the photoreceptors 8 of the respective colors Y, M, and C. Therefore, by setting threshold values in advance for the torque differences Ye, Me, and Ce, it is possible to individually determine the deterioration of the Y, M, and C color photoreceptors 8. This is because if any of the measured torque differences Ye, Me, and Ce has reached the threshold, the deterioration of the photoconductor 8 of the corresponding color has reached the level indicated by the threshold. For this reason, the notification unit 22 can be used to output an appropriate message such as replacement recommendation or replacement request for the corresponding photosensitive member 8. Alternatively, measures can be taken to prohibit image formation.

  Alternatively, the deterioration determination can be performed more precisely. For this purpose, the initial value of the drive current value is used. As described with reference to FIG. 4, the four current values (a) to (d) are all small at the initial stage of durable use. Further, the difference (torque difference) between the current value of (a) and the current values of (b) to (d) is also small. Therefore, if current measurement similar to that in FIG. 6 is performed when all the Y, M, and C photoconductors 8 are new, a graph as shown in FIG. 7 is obtained. Yf, Mf, and Cf in FIG. 7 are initial values (initial differences) of the aforementioned torque differences Ye, Me, and Ce, respectively. These are all smaller than the torque differences Ye, Me, and Ce (post-use differences) in FIG.

  Therefore, the initial differences Yf, Mf, and Cf measured when new are stored in the control unit 17. When the post-use differences Ye, Me, and Ce are obtained in the deterioration determination of the photoconductor 8 during durable use, the increment is calculated by subtracting the initial difference from the post-use difference for each color. By setting a limit value for this increment in advance, a more precise deterioration judgment can be made. That is, when the increment reaches the limit value, it is considered that the torque difference has reached the threshold value. Of course, the limit value in this case may have a plurality of levels such as a notice stage and an image formation prohibition stage. The initial difference in FIG. 7 has been described above as “when it is new”, but it may be when the Y, M, and C photoconductors 8 are replaced other than when they are new.

  Furthermore, in this embodiment, it is possible to perform the deterioration determination more precisely by using the environmental sensor included in the “each sensor 21” described above. This is because the rotational resistance of the photoconductor 8 has a portion that depends on environmental factors such as temperature and humidity. For example, the mechanical resistance of the drive transmission mechanism from the color motor 15 to the photoconductor 8 tends to be large at low temperatures and small at high temperatures. Therefore, it is preferable to perform a correction process based on temperature when converting the current value to the torque value.

  Therefore, for example, as a conversion table from current values to torque values, a table corresponding to a plurality of levels (here, two levels) of temperatures as shown in Table 1 can be used. In Table 1, for any current value, a higher torque value is specified in the low temperature (15 ° C.) column than in the high temperature (25 ° C.) column. As a result, at low temperatures with high mechanical resistance, the same current value is converted into a larger torque value. That is, the torque value is reduced at a high temperature, and the torque value is emphasized at a low temperature. In this way, a more precise deterioration determination is performed. Of course, a conversion table with more temperature levels may be used.

  Further, not only the temperature but also the humidity can be corrected when converting the current value to the torque value. In the case of humidity, the higher the humidity, the higher the rotational resistance of the photoconductor 8 in the toner supply state. This is because the toner absorbs moisture easily and becomes agglomerated, and the lubricity is low accordingly. For the correction by humidity, a plurality of conversion tables as described above can be prepared. A conversion table corresponding to a plurality of levels including both temperature and humidity conditions may be prepared.

  The deterioration determination of the photoreceptor 8 as described above is executed at an appropriate timing other than the time of image formation. In general, it is performed every fixed number of image formation sheets (for example, 10,000 sheets). However, since this determination is performed as life management of the photoconductor 8, it can be said that it is not necessary to perform this determination while the remaining life is sufficient. Therefore, the initial determination condition after the start of use is set, and the deterioration determination may not be performed until the accumulated image formation amount satisfies the initial determination condition. That is, the deterioration determination is performed after the accumulated image formation amount reaches a predetermined value. As an initial determination condition, for example, 300,000 cumulative image formations can be considered. As for the cumulative image formation amount, the count value may be stored in the control unit 17.

  On the other hand, as the remaining life of the photoconductor 8 decreases, it can be said that the necessity of performing deterioration determination increases. Here, from the description of FIGS. 4 and 6 and the like, the torque difference and the increase increase with the decrease in the remaining life (increase in the number of accumulated images). That is, as the torque difference and increment increase and approach the above-described threshold value and limit value, the necessity for performing deterioration determination increases. For this reason, even if it is determined that none of the photoreceptors is deteriorated by the deterioration determination, it can be said that it is better to increase the frequency of deterioration determination in the above situation. Therefore, it is preferable to set the interval until the next determination is made shorter as the torque difference and the increment rise within a range that does not reach the threshold and limit values. As a result, when the remaining life is long, the deterioration determination execution frequency is lowered to suppress toner consumption, and when the remaining life is shortened, the deterioration determination execution frequency is increased to prevent overuse of the photoconductor 8. Can do.

  As described above in detail, according to the present embodiment, the deterioration determination of the photoconductor 8 is performed based on the drive torque value of the color motor 15 that drives the three photoconductors 8. For this purpose, the deterioration of the three photoconductors 8 is determined individually by taking the torque difference between the state in which the color motor 15 is rotated and no toner is supplied and the state in which only one color toner is supplied. Like to do. As a result, the image forming apparatus 1 capable of individually managing the life of the photoconductor 8 by torque measurement for each photoconductor 8 is realized. By making such a determination, unlike the case where the determination is simply based on the cumulative number of image formations, the photoconductor 8 that has not yet deteriorated is not replaced. On the other hand, even if the deterioration progresses earlier than usual, the deterioration determination is made appropriately.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, in the present embodiment, the deterioration determination for the three photosensitive members 8 driven by the color motor 15 which is a common drive source has been described. Although the description of the deterioration determination of the K-color photosensitive member 8 driven by the black motor 16 is omitted, the deterioration determination can be similarly performed based on a concept such as a torque difference. The present invention can also be applied to an image forming apparatus configured to drive all color photoreceptors including K color by one motor. Of course, the total number of colors is not limited to four.

  In the present embodiment, as described with reference to FIG. 5, the toner is supplied to the entire cleaning width to determine the deterioration. However, this is not essential, and it is also possible to determine the deterioration by supplying toner only to a part of the cleaning width. This is disadvantageous because it does not measure the torque reflecting the overall wear state of the cleaning width. However, this is practically sufficient for applications where small-size paper is often used.

  Further, the target image forming apparatus 1 may be not only the printer type shown in FIG. 1 but also a copier type having a scanner unit. Further, it may be provided with a function of transmitting and receiving an image forming job via a public line. The toner used may be one-component or two-component.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image forming part 8 Photoconductor 14 Cleaning blade 15 Color motor 17 Control part (Degradation determination part, environmental correction part, initial state memory | storage part, image formation amount integrating | accumulating part)
19 Drive circuit (torque measurement unit)
21 Each sensor

Claims (6)

Having multiple image forming units,
Each of the plurality of image forming units is
A photoreceptor,
A developing unit for applying toner to the photoreceptor;
A stationary cleaning member for removing toner on the photosensitive member,
An image forming apparatus for forming an image on a medium by transferring toner onto the medium before being applied to the photosensitive member from the developing unit and removed by the cleaning member,
A common drive source for rotationally driving the photoreceptors of the plurality of image forming units;
A torque measuring unit that outputs an index value of torque during rotation of the common drive source;
A deterioration determination unit that individually determines deterioration states of the photoreceptors of the plurality of image forming units when not during image formation;
The deterioration determination unit
Obtaining a first torque value that is an output value of the torque measurement unit when the common drive source is driven in a state where toner is not applied to any of the photoreceptors of the plurality of image forming units;
A second torque value that is an output value of the torque measurement unit when the common drive source is driven in a state where toner is applied to any one of the plurality of image forming units; If the torque difference, which is the difference obtained by subtracting the second torque value from the torque value, is not large enough to correspond to a predetermined deterioration determination event, the photoconductor to which toner is applied at the time of obtaining the second torque value is still Judge that it has not deteriorated,
When the torque difference is large enough to correspond to the deterioration determination event, it is configured to determine that the photoreceptor to which toner is applied is deteriorated when the second torque value is acquired. Image forming apparatus. The image forming apparatus according to claim 1,
An initial state storage unit that stores, for each of the plurality of photosensitive members, an initial difference that is the torque difference when any of the plurality of image forming units is in an initial state;
The deterioration determination unit
Obtaining the first torque value and the second torque value for each of the plurality of photoconductors after start of use;
The difference after use which is the torque difference after the start of use is configured to be compared with the initial difference for each of the plurality of photoconductors.
2. The image forming apparatus according to claim 1, wherein an increase obtained by subtracting the initial difference from the post-use difference is larger than a predetermined limit value, which is the deterioration determination event for the photoconductor. 3. The image forming apparatus according to claim 1, wherein the deterioration determination unit includes:
The toner is applied to the photosensitive member of the image forming unit when the second torque value is acquired, and is applied to the entire range in the width direction where the toner is removed by the cleaning member of the image forming unit. An image forming apparatus. An image forming apparatus according to any one of claims 1 to 3, wherein
An image formation amount integration unit for integrating the cumulative execution amount of image formation from the initial state;
The image forming apparatus, wherein the deterioration determination unit is configured to determine the deterioration state of the photosensitive member after the integrated value of the cumulative execution amount reaches a predetermined predetermined value. 5. The image forming apparatus according to claim 1, wherein the deterioration determination unit includes:
When it is determined by the determination of the deterioration state of the photoconductor that none of the photoconductors are deteriorated, the interval until the next determination is set shorter as the latest acquired torque difference is larger. An image forming apparatus. An image forming apparatus according to any one of claims 1 to 5, comprising:
An environment detection unit for acquiring at least one of temperature and humidity;
For the output value of the torque measurement unit,
A temperature correction that reduces the value as the temperature increases and emphasizes the value as the temperature decreases;
An environmental correction unit that performs at least one of humidity correction that emphasizes the value as the humidity increases and reduces the value as the humidity decreases;
The image forming apparatus characterized in that the deterioration determining unit is configured to determine a deterioration state of the photosensitive member using the first torque value and the second torque value that have been corrected by the environment correcting unit. apparatus.

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