JPH11352852A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device by which a user can previously know the optimum term for maintenance and exchange of a blade, etc., so that needless cost can be saved, and also by which toner passing can be prevented. SOLUTION: This image forming device provided with a photoreceptor (image carrier) 1, a motor (driving means) 3 rotating and driving the photoreceptor 1, and a cleaning device (cleaning means) brought into press-contact with the photoreceptor 1 and removing the residual toner on the photoreceptor 1 is provided with a current detecting part (torque detecting means) 4 detecting the driving torque of the photoreceptor 1, a deciding means deciding whether or not the maintenance or the parts exchange of the cleaning device or the photoreceptor 1 is needed based on the detection result of the means 4, or a predicting means predicting the term for the need of the maintenance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrostatic copying machine and an electrostatic printer, and more particularly to the convenience of maintenance of a cleaning device and an image carrier.

[0002]

2. Description of the Related Art In a known image forming apparatus for obtaining a print image by transferring a toner image electrostatically formed on an image carrier to a transfer material such as paper, the image is not transferred to the transfer material after the transfer process. As cleaning means for removing toner remaining on the carrier, the edge of a blade formed into a plate shape with an elastic material such as rubber is pressed against the image carrier to scrape off residual toner and remove it. Things are widely used.

The above-mentioned blade cannot be used forever. During the printing process, the edge of the image carrier is worn or broken due to the rubbing of the blade and the image carrier or the permanent deformation due to the deterioration of the rubber material. A sufficient pressure contact force cannot be obtained, so that the toner cannot be completely removed and the toner slips through. There is no other way to recover the removal function of the blade having the reduced removal function, except to replace the blade with a new blade.

[0004] Even if the blade is not damaged or permanently deformed, toner slippage may occur due to other factors. A corona charger is often used in the charging step and the transfer step for charging the image carrier, and the ozone released from the corona charger reacts with nitrogen in the air to form nitrogen oxides, Further, it is well known that this nitrogen oxide reacts with water, paper powder, toner and the like emitted from transfer paper under high humidity to generate nitrate.

When the nitrate adheres to the surface of the image carrier, the frictional force between the image carrier and the blade may increase. If the frictional force is large, the blade is dragged in the running direction of the image carrier and the edge is moved in the running direction. This causes a so-called blade turn that is bent and deformed. The curled blade loses the ability to block the toner at the edge, causing the toner to slip through.

Further, in order to improve the charging performance of the toner, fine resin particles are often added to and mixed with the toner particles, and such fine resin particles penetrate between the blade edge in use and the image carrier and penetrate. When the amount of the fine particles increases, a part of the edge separates from the image carrier, so that the toner slips through. Then, even when a part of the accumulated fine particles is missing, a gap is formed between the edge and the image carrier at that location, so that the toner slips through.

Conventionally, in these cases, cleaning is performed by wiping off contaminants adhering to the image carrier with a cleaning paper impregnated with alcohol containing abrasive particles, or removing a resin fine particle accumulated on a blade edge with a brush. The cleaning performance of the blade was maintained by performing maintenance.

[0008]

However, the blade replacement and cleaning maintenance described above are often performed after the toner slips through, and until the maintenance is performed after the toner slips out. The toner that has slipped through is transferred to the image printed during this period, which results in a misprint in practical use. For this reason, paper and toner are wasted and wasteful.

Further, if the apparatus is continuously used by mistake while the blade is turned up, not only permanent deformation or breakage of the edge occurs but also an excessively large load acts locally on the surface of the image carrier. In this case, the photosensitive layer may be destroyed or the surface layer may be peeled off. In this case, it is necessary to replace not only the blade but also the image carrier, thereby increasing the cost of consumables.

In order to avoid the above-mentioned situation, it is necessary to replace or maintain the blade before toner slips through. However, since there is no means for detecting the state of the blade being used, the replacement or maintenance is not possible at any time. It is not possible to predict whether or not maintenance is required, and the maintenance is inevitably performed by frequently removing the cleaning device, resulting in a problem that the burden on the user is large.

[0011] Even if the blade still has sufficient cleaning performance, it is often replaced sooner, which increases the cost of consumables.

By the way, from the results of the continuous use test of the blade, the number of prints as a guide for blade replacement is determined to a certain extent, but this is a guaranteed number of prints under certain use conditions, The optimum number of replacement sheets varies depending on the lot variation of the performance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and the object thereof is to know in advance the optimal maintenance and replacement time of a blade or the like so that unnecessary costs can be saved, and the toner cost can be reduced. An object of the present invention is to provide an image forming apparatus capable of preventing slip-through.

[0014]

According to a first aspect of the present invention, there is provided an image bearing member, a driving unit for rotating the image bearing member, and an image bearing member pressed against the image bearing member. In an image forming apparatus provided with a cleaning unit for removing residual toner on an image carrier, a torque detecting unit for detecting a driving torque of the image carrier, and the cleaning unit or the image based on a detection result of the torque detecting unit. A determination means for determining whether maintenance of the carrier or replacement of parts is necessary, or a prediction means for predicting a required maintenance time is provided.

According to a second aspect of the present invention, in the first aspect of the present invention, a DC motor having a control circuit for maintaining a constant rotation speed is used as the driving means, and a load current, an input voltage, and power consumption of the DC motor are used. The torque is detected by any one of the following.

According to a third aspect of the present invention, in the first aspect of the present invention, the determining means includes a cleaning means or a cleaning means for cleaning the surface of the image carrier when the driving torque of the image carrier reaches a predetermined upper limit or lower limit. It is determined that maintenance is necessary.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the determination means determines that the print after the previous cleaning maintenance has been performed when the driving torque of the image carrier has reached a predetermined upper limit or lower limit. When the number of sheets does not reach the predetermined number, it is determined that the cleaning means needs to be replaced.

According to a fifth aspect of the present invention, in the first aspect of the invention, if the driving torque of the image bearing member does not fall within a predetermined range after the attachment or replacement of the cleaning unit, the determining unit determines whether or not the cleaning unit has the same. It is characterized in that it is determined that reattachment or replacement is necessary.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the predicting means prints the driving torque at which the driving torque reaches an upper limit or a lower limit based on a change amount of the driving torque of the image carrier per a predetermined number of prints. The number of sheets is predicted.

Therefore, according to the present invention, a torque detecting means for detecting the driving torque of the image carrier is provided as means for detecting the cleaning performance of the blade in use, and the image carrier detected by the torque detecting means is provided. Based on the driving torque, it is determined whether the maintenance of the cleaning means or the image carrier or the replacement of parts is necessary, or the time required for the maintenance is predicted, so that the optimal maintenance and replacement time of the blade or the like is determined in advance. It is possible to avoid unnecessary costs that can be known and to prevent toner from slipping through.

[0021]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1> FIG. 8 is a cross-sectional view of a cleaning device portion of an image forming apparatus according to the present invention. In FIG. 8, reference numeral 1 denotes a photosensitive member, and the photosensitive member 1 has an amorphous structure on a conductive substrate. It is formed by forming a photoconductive layer of silicon or the like, and is rotatably supported in the direction of the arrow shown in the figure.

Reference numeral 2 denotes a cleaning device. The housing 20 of the cleaning device 2 has an opening on the photoconductor 1 side, and a blade 21 is pressed against the photoconductor 1 at the opening. The blade 21 is made of urethane rubber or the like formed in a plate shape having substantially the same length as the axial length of the photoconductor 1, and one edge of the blade 21 is uniformly formed in the axial direction.
It is pressed against the surface. The blade 21 is fixedly held by two sandwiching members 26 and 27, and is rotatable around an axis 28 parallel to the axis of the photoconductor 1.
7 is pressed against the photoreceptor 1 by a spring 29 fixed to one end of the sandwiching member 27. The blade 21 may be fixed to the housing 20 without using the spring 29 and may be pressed against the photoconductor 1.

By the way, the toner D remaining on the photoreceptor 1 after the transfer step is sent to the edge of the blade 21 with the rotation of the photoreceptor 1 and is scraped off. The scraped-off toner D is conveyed by the rotating conveying roller 23. Then, the toner is removed from above the transport roller 23 by the scraper 24 and sent to the screw 25. The screw 25 transports the toner D in the axial direction, and the toner D is collected in a collection box (not shown) arranged at the back of the apparatus.

Here, the relationship between the frictional force acting between the blade 21 and the photosensitive member 1 and the toner scraping ability will be described.

Since the blade 21 is pressed against the photosensitive member 1, a certain frictional force is generated between the blade 21 and the photosensitive member 1. If this frictional force is within the predetermined range, the blade 21 can rub the photoconductor 1 appropriately without being damaged, and can sufficiently scrape off the toner D. However, as the blade 21 is continuously used, the frictional force increases and decreases, and the scraping ability is lost.

FIGS. 9 and 10 show how toner slips through when the frictional force is too large.

FIG. 9 shows a state in which the toner slips through when the contaminant 11 such as nitrate is firmly adhered to the surface of the photoreceptor 1 by repeating the charging step and the transfer step. When the contaminant 11 adheres to the surface of the photoreceptor 1 in this way, the blade 21 does not contact the photoreceptor 1 and rubs against the contaminant 11, so that the frictional force increases. If the frictional force is large, so-called chattering occurs in which the edge of the blade 21 vibrates minutely, or the edge of the blade 21 is dragged in the rotation direction of the photoconductor 1 and the blade 21 is turned up. FIG. 9 shows a state in which the edge of the blade 21 is turned up.

When the blade 21 is turned up as described above, the edge of the blade 21 does not come into contact with the photosensitive member 1, so that a part of the residual toner D is not scraped off by the edge.
Slip-through toner D 'occurs. Further, when chatter occurs in the blade 21, the edge is locally separated from the surface of the photoconductor 1, and a gap is generated between the two, and toner slips through the gap.

FIG. 10 shows a state in which the blade 21 is gradually worn due to the rubbing between the blade 21 and the photoreceptor 1. In the drawing, S indicates an area where the edge of the blade 21 has been cut off due to wear.

Although the edge of the blade 21 contacts the photoreceptor 1 almost at one point, the frictional force increases because the contact area of the blade 21 increases when the edge is cut off.
For this reason, chatter and turning of the blade 21 occur, and toner slippage occurs. In addition, since the edge of the blade 21 is shaved, a portion where the edge does not contact the photoconductor 1 locally occurs, and the toner slips through the portion.

FIGS. 11 and 12 are views showing a state in which toner slips through because the frictional force is too small.

FIG. 11 shows resin fine particles G ′ mixed with the toner.
Shows a state in which is accumulated at the edge portion of the blade 21. The resin fine particles G ′ are weakly charged to the same polarity or opposite polarity to the toner, and a small amount adheres electrostatically to the photoconductor 1 when forming a toner image, and the resin fine particles G remaining after the transfer are removed. It is carried to the edge of the blade 21. Then, the accumulation amount of the resin fine particles G gradually increases, and if the number of particles entering between the edge and the photoconductor 1 increases, it causes the toner to slip through. In this case, since the resin fine particles G exist between the edge of the blade 21 and the photoconductor 1, the edge does not contact the photoconductor 1, and the frictional force between the two is reduced.

FIG. 12 shows a state in which the blade 21 is hardened and deformed while being pressed against the photosensitive member 1, and the hardened deformation of the blade 21 easily occurs at a low temperature. The hardened blade 21 loses the repulsive force and therefore has a weak pressing force against the photoreceptor 1, so that the toner easily slides out and the frictional force is small.

If the blade 21 is functioning normally, the friction force has an appropriate range, and if the friction force becomes excessively large or small for some reason, the toner scraping ability is reduced. Therefore, if the value of the frictional force is known, it can be determined whether the blade 21 is functioning normally.

On the other hand, the rotational torque required to rotate the photosensitive member 1 against the frictional force is proportional to the magnitude of the frictional force. Therefore, if the torque can be detected instead of the frictional force, the performance of the blade 21 can be determined.

FIG. 13 shows the relationship between the frictional force (static frictional force) and the rotational torque (static torque) of the photosensitive member. FIG. 13 shows a photosensitive member having a diameter of 100 mm, an axial length of 360 mm,
The relationship when a drum having a weight of 1500 g is used and the total pressure of the blade against the photosensitive member is 420 g is shown.

As is apparent from FIG. 13, when the frictional force is large, the torque is also large. When the torque is Tmax = 6 kg or more, the toner slips through. Further, when the frictional force is small, the torque is also small, and when the torque is Tmin = 2 kg or less, slippage of the toner occurs. Therefore, the appropriate value of the torque is 2.5 kg to 5.5 kg.

Next, the configuration of the image forming apparatus according to this embodiment will be described.

FIG. 1 is a block diagram showing the configuration of an image forming apparatus according to the present embodiment. In FIG. 1, reference numeral 1 denotes a photosensitive member, and the photosensitive member 1 is driven to rotate at a constant speed by a motor 3. Reference numeral 4 denotes a current detector for detecting a current flowing through the motor 3, and reference numeral 5 denotes a power supply for supplying a voltage to the motor 3.

The motor 3 is a well-known DC motor having a control circuit for keeping the rotation speed constant. When the rotation torque of the photosensitive member 1 increases based on a signal from the speed detection circuit and the speed decreases, the motor 3 The speed is kept constant by increasing the input voltage and the load current to the motor 3 for correcting the decrease. At this time, the power consumption of the motor 3 also increases. Similarly,
When the torque increases and the speed increases, the voltage and current are reduced to keep the speed constant in order to compensate for the increase in speed. At this time, the power consumption of the motor 3 decreases.

FIG. 2 shows the relationship between the load current of the motor 3 and the rotation torque of the photosensitive member 1, and the load current and the rotation torque are in a proportional relationship as shown. Therefore, if the current is detected, the torque of the photoconductor 1 can be calculated. still,
Instead of current, voltage or power may be detected.

In the present embodiment, the torque is detected by detecting the current by the current detector 4. The current signal from the current detection unit 4 is sent to the control unit 6 and converted into a torque.

In FIG. 1, reference numeral 9 denotes a counter for integrating the number of prints, and a count signal from the counter 9 is sent to the control unit 6. Then, the control unit 6 determines whether or not the magnitude of the frictional force between the blade 21 and the photoconductor 1 is normal from the calculated torque and the count. If the magnitude is abnormal, the control unit 6 displays the value on the display unit 7 provided on the operation panel or the like of the apparatus. A display requesting maintenance or replacement of the blade 21 or the photoconductor 1 is performed.
This request is in a remote place away from the main unit,
The information may be transmitted to the external display unit 8 connected to the device via a telephone line or a dedicated communication line.

FIGS. 3 and 4 are diagrams showing changes in torque detected by the above method. FIG. 3 shows a case where the torque increases with the number of prints, and FIG. 4 shows a case where the torque decreases. Is shown.

As a case where the torque is increased, there is a case where the apparatus is used under high humidity, so that a large amount of contaminants adhere to the photoreceptor 1 and a large amount of the edge of the blade 21 is scraped off due to friction. Further, as a case where the torque is reduced, a case where a large amount of resin fine particles are mixed with the toner at a low temperature is used. In many cases, not only the torque simply increases or decreases but also increases and decreases in many cases. Here, a case where the torque simply increases or decreases will be described to make the description easy to understand.

In FIG. 3, the initial torque is 4 kg, which is in an appropriate range. This increases with the number of prints, and when the cumulative number of sheets from the beginning is X1 = 200,000, the upper limit T of the appropriate range is obtained.
U reaches 5.5 kg.

The control unit 6 compares the detected torque with the upper limit value TU, determines that the torque is abnormal when the torque exceeds the upper limit value TU, and issues a predetermined limit signal.
The display unit 7 or the external display unit 8 displays a request for cleaning the photoconductor 1 upon receiving the limit signal, and the maintenance worker performs a cleaning operation in accordance with the display.

When contaminants are removed from the surface of the photosensitive member 1 by cleaning the photosensitive member 1, the frictional force returns to the initial value,
The blade 21 can be used continuously again. After that, if you continue printing, contaminants will adhere again,
When X2 = 360,000 sheets, the torque reaches the upper limit value TU, and at this time, the display of the cleaning request and the cleaning operation based on this are performed as described above.

As described above, while the cleaning of the photosensitive member 1 and the continuous use of the blade 21 are repeated, the edge of the blade 21 is gradually scraped, and the frictional force does not recover to the initial value even when the photosensitive member 1 is cleaned. . For this reason, the number of prints from when cleaning is performed until the torque reaches the upper limit value TU decreases.

The operator resets the counter 9 at the time of cleaning, and the counter 9 records the total number of sheets Y from the previous cleaning. In the control unit 6, the torque is set to the upper limit value TU.
When the count reaches Y0, the count is compared with the predetermined number Y0. If the count is equal to or less than Y0, it is determined that the cutting of the edge is large, and a display requesting replacement of the blade 21 is displayed on the display unit 7 or the like. Command. When the edge of the blade 21 is shaved, the frequency of cleaning by the operator increases and the cleaning cost increases. Therefore, it is more economical to replace the blade 21. In this embodiment, the predetermined number Y0 = 30,000 is set for a blade manufactured so that 500,000 sheets can be continuously used as a standard.

In the example shown in FIG. 4, the operation of the apparatus is performed through the same process as described above. However, in this case, the torque decreases with the number of prints Z, and the torque decreases to the lower limit value TL =
When the weight reaches 2.5 kg, a display requesting cleaning of the blade 21 and the photoconductor 1 is performed. The operator cleans the edge of the blade 21 to remove the resin fine particles accumulated on the edge and also removes the resin fine particles adhered to the photoconductor 1.

When the count W becomes equal to or less than the predetermined number Y0, it is determined that the permanent deformation of the blade 21 is large, and a display requesting replacement of the blade 21 is displayed. The above process is shown by a flowchart in FIG.

As for the timing of torque detection,
This is performed when the power of the apparatus is turned on, at the time of warming-up rotation of the photoconductor 1 or at the time of pre-rotation for each print. In consideration of the fact that the frictional force fluctuates at the circumferential position of the photoreceptor 1, sampling of the torque detection is performed by detecting the maximum and the minimum of the torque continuously during at least one rotation of the photoreceptor 1, and setting the maximum value to the upper limit value. Used for comparison with TU, and the minimum value is used for comparison with lower limit TL.

In the present embodiment, since the use state of the blade 21 can be known from the displayed contents, it is possible to prevent the toner from slipping off by cleaning maintenance and replacement of the blade 21 in advance, and it is also necessary for the operator. The trouble of disassembling the apparatus unnecessarily and checking the cleaning device 2 can be omitted.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG.

The first embodiment is for monitoring blade performance over a long period of time. However, by detecting torque immediately after blade installation or blade replacement, incorrect blade installation or use of defective blades is detected. Can be avoided.

FIG. 6 is a diagram showing the torque change immediately after the initial installation of the blade or after the blade has been removed for cleaning or replacement and immediately after the blade has been installed again, when the number of prints is 1,000 or less.

The change in torque when the non-defective blade is correctly attached generally changes as shown by curve b. The initial (number of prints = 0) torque is slightly higher, but the torque decreases with the number of prints, and the initial torque decreases. Within the proper range (within the range of tmin 3.5 kg to tmax 4.5 kg)
Converges to This is because the residual toner is supplied to the edge of the blade by the printing operation, the toner acts as lubricating particles, and the sliding property between the blade and the photoconductor increases.

On the other hand, a curve a shown in FIG. 6 shows a change in torque which is observed when the mounting position of the blade is displaced or when a defective rubber rubber having a different hardness is used. Since an abnormal load acts, the torque does not fall within the proper range of the initial torque, and the transition of the torque varies. If the blade is continuously used as it is, the edge of the blade cannot withstand the load at some point and the torque rapidly increases in a short time, and the upper limit value T
May exceed max. In such a case, if the detection timing is late, the torque abnormality cannot be determined,
The blade may be turned or chattered, causing toner to slip through.

In order to prevent the above, the torque immediately after the installation of the blade or immediately after the blade replacement is continuously detected, and the torque does not fall within the initial appropriate range within the predetermined number P (500 in the present embodiment). In such a case, the above problem can be avoided by determining that there is an abnormality and performing a display requesting re-installation of the blade or replacement of the blade with a non-defective product.

<Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIG.

In the present embodiment, the number of prints that require cleaning or replacement of the blade or the like is predicted from the data on the torque change up to a certain point.
The method is shown in FIG.

FIG. 7 shows an example of a case where the torque increases. The blade is used until the number of prints = X, and the torque at that time is Y. In the present embodiment, a case where Y reaches upper limit value TU will be described. The torque at X0 before X was Y0. That is, the increase in torque between prints X-X0 is Y-Y0.

Since it is considered that the torque increases with substantially the same gradient after X, the number of prints Xmax at which the torque reaches the limit value Tmax can be predicted as follows. That is, Xmax is calculated by the following equation using a straight line approximation: Xmax = (Tmax−Y0) · (X−X0) / (Y−Y)
0) + X0.

The print interval XX0 for determining the inclination of the straight line represented by the above equation is an appropriate value for 10,000 to 20,000 sheets. Therefore, if a change in torque is stored in a memory (not shown) at smaller intervals (1000 to 2000 sheets), the inclination at an arbitrary number of prints can be determined by reading out the data, and the limit number Xmax is predicted. can do.

In this embodiment, X−X0 = 20,000 sheets, Y
= TU = 5.5 kg, Y0 = 5 kg to Xmax = X + 2
It will be 10,000 copies. That is, it is understood that cleaning or replacement is required after about 20,000 sheets. This prediction is performed by the control unit 6, and the prediction result is displayed on the display unit 7 or the like. This allows the operator to know the optimal maintenance time in detail, and does not hasten cleaning or replacement. Therefore, the frequency of cleaning and replacement is reduced, and maintenance costs can be reduced.

[0068]

As is apparent from the above description, according to the present invention, torque detecting means for detecting the driving torque of the image carrier is provided as means for detecting the cleaning performance of the blade in use. The maintenance means of the image carrier or the maintenance of the image carrier or the replacement of parts is determined based on the driving torque of the image carrier detected by the means, or the time required for the maintenance is predicted. It is possible to obtain the optimum maintenance and replacement timing in advance so that unnecessary costs can be saved and the toner can be prevented from slipping through.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image forming apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a diagram illustrating a relationship between a load current of a motor and a rotation torque of a photoconductor.

FIG. 3 is a diagram illustrating a transition example 1 of a rotation torque of a photoconductor in an image forming apparatus according to a second embodiment of the present invention;

FIG. 4 is a diagram illustrating a second transition example of the rotation torque of the photoconductor in the image forming apparatus according to the second embodiment of the present invention;

FIG. 5 is a flowchart illustrating a control flow of the image forming apparatus according to Embodiment 1 of the present invention.

FIG. 6 is a diagram showing a transition of a rotation torque of a photoconductor in an image forming apparatus according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a method for predicting a maintenance time in an image forming apparatus according to a third embodiment of the present invention;

FIG. 8 is a sectional view of a cleaning device portion of the image forming apparatus according to the present invention.

FIG. 9 is a diagram illustrating a state 1 (edge turning) in which toner slippage occurs.

FIG. 10 is a diagram illustrating a state 2 (edge scraping) in which toner slippage occurs.

FIG. 11 is a diagram illustrating a state 3 (accumulation of resin fine particles) in which toner slippage occurs.

FIG. 12 is a diagram illustrating a state 4 (permanent deformation of an edge portion) in which toner slippage occurs.

FIG. 13 is a diagram illustrating a relationship between frictional force and torque.

[Explanation of symbols]

 Reference Signs List 1 photoconductor (image carrier) 2 cleaning device (cleaning means) 3 motor (drive means) 4 current detection unit (torque detection means) 5 power supply 6 control unit (judgment means) 7 display unit 8 external display unit 9 counter 21 blade

Claims (6)

[Claims] 1. An image forming apparatus comprising: an image carrier; a driving unit that rotationally drives the image carrier; and a cleaning unit that is pressed against the image carrier and removes residual toner on the image carrier. A torque detecting unit that detects a driving torque of the image carrier, and a determining unit that determines whether maintenance or part replacement of the cleaning unit or the image carrier is necessary based on a detection result of the torque detecting unit, or An image forming apparatus, comprising: a prediction unit that predicts a required maintenance time. 2. The method according to claim 1, wherein a DC motor having a control circuit for keeping the rotation speed constant is used as the driving means, and the torque is detected by any one of a load current, an input voltage, and power consumption of the DC motor. Item 2. The image forming apparatus according to Item 1. 3. The image forming apparatus according to claim 1, wherein the determining unit determines that the cleaning unit or the cleaning maintenance of the surface of the image carrier is necessary when the driving torque of the image carrier reaches a predetermined upper limit or a lower limit. The image forming apparatus as described in the above. 4. The method according to claim 1, wherein when the drive torque of the image carrier reaches a predetermined upper limit or a lower limit, the number of prints after the previous cleaning maintenance does not reach the predetermined number. The image forming apparatus according to claim 3, wherein the image forming apparatus determines that the image is necessary. 5. The method according to claim 1, wherein the determining unit determines that the cleaning unit needs to be mounted or replaced again if the driving torque of the image carrier does not fall within a predetermined range after the mounting or replacement of the cleaning unit. The image forming apparatus according to claim 1. 6. The printing apparatus according to claim 1, wherein the prediction unit predicts the number of prints at which the drive torque reaches an upper limit value or a lower limit value from a change amount of the drive torque of the image carrier per a predetermined number of prints. Image forming device.