JP2010231057A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device allowing a user to obtain a state of a plate-like cleaning member to be brought into contact with at least an image holding face of an image holder accurately and reducing a load to receive due to the contact of the cleaning member with the image holding face in accordance with the obtained state properly. <P>SOLUTION: The image forming device includes the rotatable image holder having the image holding face for holding image, the plate-like cleaning member installed while it is fixed to bring a free end into contact with at least the image holding face of the image holder and clean the image holding face, a distortion detection means for detecting distortion of the cleaning member, and a load reducing means for reducing the load that receives due to the contact of the cleaning member with at least the image holding face by utilizing information of the distortion detected by the distortion detection means. The distortion detection means is composed of: a first distortion detection means attached onto a surface part on a free end side of the cleaning member; and a second distortion detection means attached onto a surface part on a fixed end side of the cleaning member. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  In image forming apparatuses such as printers, copiers, and facsimiles that employ recording methods such as electrophotography, unnecessary deposits such as toner adhering to the surface (image holding surface) of an image carrier such as a photoreceptor are removed. In order to do so, there is a case where a cleaning device is installed in a state where a cleaning member made of a plate-like elastic blade or the like is in contact with the image holding surface.

  In addition, in an image forming apparatus equipped with this cleaning device, discharge products such as nitrogen oxides generated by discharge during the charging process of the image carrier and the like are applied to the image carrier surface of the image carrier in a high temperature and high humidity environment. For this reason, for example, there is a phenomenon that the coefficient of friction between the cleaning member of the cleaning device and the image holding surface becomes large and the cleaning member is turned up or the image holding surface of the image holding member is worn. It tends to be promoted.

  Conventionally, as an image forming apparatus equipped with such a cleaning device, a deformation detecting means such as a strain gauge for detecting the bending deformation of the blade pressed against the surface of the photoreceptor is provided on the surface of the blade, and the deformation detection is performed. There is known an image forming apparatus provided with a cleaning device that attaches toner to a non-image area of a photoreceptor by a developing unit based on a detection signal of the unit and supplies the toner to a blade (Patent Document 1).

  In addition, the vibration of the elastomer blade or the supporting member to be brought into contact with the image carrier is measured, and the index value based on the normal state with multi-dimensional data for each frequency obtained by Fourier transform of the vibration as a signal. An image forming apparatus provided with a cleaning device that detects abnormalities in the contact state of the blade, such as the presence or absence of deposits or scratches on the rotating body, is known (Patent Document 2).

Japanese Patent Laid-Open No. 7-230239 JP 2006-106017 A

  The present invention accurately grasps the state of the plate-shaped cleaning member brought into contact with at least the image holding surface of the image holding member, and appropriately applies the load received from the contact with the image holding surface of the cleaning member according to the grasped state. It is an object of the present invention to provide an image forming apparatus that can be reduced.

An image forming apparatus according to the present invention (A1) has an image holding surface that holds an image and rotates,
A plate-like cleaning member installed in a state where the free end is in contact with at least the image holding surface of the image holding body and is fixed so as to clean the image holding surface;
Strain detecting means for detecting strain of the cleaning member;
Load reducing means for performing an operation of reducing a load received by contact with at least the image holding surface of the cleaning member using information on distortion detected by the distortion detecting means;
The strain detecting means is composed of a first strain detecting means attached to the surface portion on the free end side of the cleaning member and a second strain detecting means attached to the surface portion on the fixed end side. It is a feature.

  The image forming apparatus of the invention (A2) is the image forming apparatus of the invention A1, wherein the cleaning member contacts the non-image holding surface area that is outside the image holding surface in the rotation axis direction of the image holding body. The first and second strain detection means are attached to the surface portion of the area corresponding to the non-image holding surface area of the image holding body in the cleaning member. .

  The image forming apparatus according to the invention (A3) is the image forming apparatus according to the invention A1 or A2, wherein the first and second strain detecting means are at the same position in the rotational axis direction of the image carrier and rotate. It is attached at a position distant from the direction.

  The image forming apparatus according to the invention (A4) is the image forming apparatus according to the invention A1, wherein the load reducing unit estimates the load of the cleaning member using information on the strain detected by the strain detecting unit. An estimation unit is included, and an operation for reducing an actual load according to the load estimated by the load estimation unit is executed.

  The image forming apparatus according to the invention (A5) is the image forming apparatus according to the invention A4, wherein the load estimating means is a non-rotating state detected by the second strain detecting means when the image carrier is not rotated. A non-rotating load is calculated based on the amount of distortion, and when the image carrier rotates, the first non-rotating amount is calculated from the amount of distortion detected by the first strain detecting means. The amount of load change calculated based on the amount of change in strain excluding the amount of strain during non-rotation detected by the strain detection means is calculated as the amount during rotation when the amount of change in load is added to the load during non-rotation It is comprised as follows.

  In the image forming apparatus according to the invention (A6), in the image forming apparatus according to the invention A5, the load estimation means actually measures a load characteristic with respect to the amount of strain at the time of non-rotation in the cleaning member, obtains a load coefficient, and stores it. The value obtained by multiplying the load coefficient by the amount of distortion during non-rotation or rotation is calculated as a load during non-rotation or rotation.

  The image forming apparatus of the invention (A7) is the image forming apparatus of the invention A5, wherein a charging device or a developing device for applying an AC voltage is disposed around the image holding member, and the strain detecting means A detection circuit for detecting the amount, and a frequency filter for removing at least a frequency component of an AC voltage applied to the charging device or the developing device is installed in the detection circuit. .

  According to the image forming apparatus of the invention A1, the actual state of the plate-like cleaning member brought into contact with at least the image holding surface of the image holding body is accurately grasped, and the image holding surface of the cleaning member is determined according to the grasped state. The load received from the contact can be appropriately reduced.

  In the image forming apparatus of the invention A2, the state of the plate-like cleaning member can be grasped more accurately, and the load on the cleaning member can be more appropriately reduced according to the grasped state.

  In the image forming apparatus of the invention A3, the state of the plate-like cleaning member can be grasped more accurately, and the load on the cleaning member can be more appropriately reduced according to the grasped state.

  In the image forming apparatus according to the invention A4, it is possible to estimate the actual load state of the plate-like cleaning member, and more appropriately reduce the load on the cleaning member according to the estimated actual load state.

  In the image forming apparatus according to the invention A5, it is possible to accurately estimate the actual load state of the plate-shaped cleaning member, and more appropriately reduce the load on the cleaning member according to the estimated actual load state. it can.

  In the image forming apparatus according to the invention A6, the state of the actual load of the plate-like cleaning member is more accurately calculated and estimated, and the load of the cleaning member is further appropriately determined according to the estimated actual load state. Can be reduced.

  In the image forming apparatus according to the invention A7, it is possible to more accurately estimate the actual load state of the plate-like cleaning member and more appropriately reduce the load on the cleaning member in accordance with the estimated actual load state. it can.

1 is an explanatory diagram showing an overview of an image forming apparatus according to an embodiment. It is explanatory drawing which shows the cleaning apparatus (elastic blade) used for the image forming apparatus of FIG. It is explanatory drawing which shows the elastic blade in the cleaning apparatus of FIG. It is sectional drawing which follows the Q1-Q1 line | wire of the elastic blade of FIG. It is explanatory drawing which shows the installation conditions of an elastic blade. It is explanatory drawing which shows an image holding surface area | region, a non-image holding surface area | region, etc. It is explanatory drawing which shows the structure of the control system with respect to a distortion | strain detection means, a load reduction apparatus, etc. It is explanatory drawing which shows the relationship of each strain state with respect to each state of an elastic blade, and each state, and load. It is a graph which shows the measurement result of the distortion amount in the free end side of the elastic blade with respect to the time of non-rotation and rotation. It is a graph which shows the measurement result of the amount of distortion in the fixed end side of an elastic blade at the time of non-rotation and rotation It is explanatory drawing which shows the load measuring machine which measures the load characteristic with respect to the distortion | strain of an elastic blade. It is a graph which shows the measurement result of the strain-load characteristic in the free end side of an elastic blade. It is a graph which shows the measurement result of the strain-load characteristic in the fixed end side of an elastic blade. It is a graph which shows the calculation result of the load (load) of the whole elastic blade at the time of non-rotation and rotation It is a graph which shows the measurement result of the amount of distortion in the free end side of an elastic blade at the time of non-rotation and rotation at the time of applying alternating current gradually. It is a flowchart which shows the control procedure regarding the measurement of a distortion amount, the operation | movement of load reduction, etc. 6 is a chart showing a toner band amount with respect to a load of an elastic blade and setting conditions for the band formation interval. It is a graph which shows the result of the evaluation test of an Example. It is a graph which shows the result of the evaluation test of a comparative example.

  Hereinafter, modes for carrying out the present invention (hereinafter simply referred to as “embodiments”) will be described with reference to the drawings.

  As shown in FIG. 1, the image forming apparatus 1 according to this embodiment forms a toner image based on image information and then transfers it to a recording medium 9 such as paper. And a fixing device 20 for fixing the toner image through the recording medium 9 on which the toner is transferred. The image forming device 10, the fixing device 20, and the like are installed inside a housing (not shown). In FIG. 1, an alternate long and short dash line with arrows indicates a main conveyance path of the recording medium 9.

  The image forming apparatus 10 is capable of forming a toner image using, for example, a known electrophotographic method. Specifically, a photosensitive drum 12 that is rotationally driven in a direction indicated by an arrow A is provided, and the surface (image holding surface) of the photosensitive drum 12 is set to a required polarity and potential around the photosensitive drum 12. A charging device 13 for charging, an exposure device 14 for irradiating light (dotted line with arrows) based on image information (signal) on the surface of the charged photosensitive drum 12 to form an electrostatic latent image having a potential difference, and A developing device 15 that forms a toner image by transferring and attaching toner of a desired color to the latent image, a transfer device 16 that transfers the toner image to a recording medium 9 supplied from a paper feeding device (not shown), and a post-transfer image A cleaning device 17 that mainly removes toner remaining on the surface of the photosensitive drum 12 and cleans it is disposed.

  Among these, the photosensitive drum 12 is formed by forming a photoconductive layer (photosensitive layer) made of an organic photosensitive material or the like on a grounded cylindrical base material. The charging device 13 is, for example, a contact charging type charging device that performs charging by applying a charging voltage from a power supply unit (not shown) to a charging roll 13 a arranged so as to rotate in contact with the surface of the photosensitive drum 12. It is.

  The exposure device 14 is composed of devices such as an LED recording head and a laser beam scanning type device. Further, the exposure apparatus 14 performs a required process on image information input from a device such as a document reading device, a stored information reading device, a personal computer, or the like connected or equipped to the image forming apparatus 1 with an image processing device (not shown). Thereafter, an image signal obtained by the processing is input. The developing device 15 transports the toner colored in a predetermined color to a developing area facing the photosensitive drum 12 while being held by a rotating developing roll 15a, and develops the electrostatic latent image. A developing voltage is applied to the developing roll 15a from a power supply unit (not shown).

  The transfer device 16 is, for example, a contact transfer type device that performs transfer by applying a required transfer voltage from a power supply unit (not shown) to a transfer roll 16 a arranged so as to rotate in contact with the photosensitive drum 12. It is. The cleaning device 17 is provided with an elastic blade 3 as a cleaning member installed so as to be in contact with the surface of the photosensitive drum 12. The elastic blade 3 is a plate-like elastic member having an external shape such as a rectangular parallelepiped.

  In the image forming device 10, the photosensitive drum 12 is charged with negative polarity, and the developing device 15 is applied with toner charged with negative polarity. Further, a voltage obtained by superimposing an AC voltage on a DC voltage is applied as a charging voltage and a developing voltage, and a DC voltage having a polarity opposite to the charging polarity of the toner is applied as a transfer voltage.

  The fixing device 20 is driven to rotate in a direction indicated by an arrow inside the housing 21 and is heated to a predetermined temperature in a roll form or a belt form, and in the axial direction of the heating rotator 22. A pressurizing rotator 23 such as a roll form or a belt form, which is pressed so as to be substantially along and driven to rotate, is installed. In the fixing device 20, the recording medium 9 on which the unfixed toner image is transferred is introduced into and passed through the press contact portion where the rotating bodies 22 and 23 are in pressure contact with each other, so that the unfixed toner image is recorded on the recording medium. 9 is fixed.

  The basic image formation by the image forming apparatus 1 is performed as follows.

  First, when the image forming apparatus 1 receives an instruction to start an image forming (printing) operation, the photosensitive drum 12 starts to rotate in the direction of arrow A in the image forming apparatus 10, and the surface of the image forming apparatus 1 has a predetermined negative polarity by the charging device 13. Then, the charged photosensitive drum 12 is exposed based on the image signal from the exposure device 14 to form an electrostatic latent image.

  Subsequently, the latent image is developed with a negatively charged toner supplied by the developing device 15 to form a toner image. Thereafter, the toner image is electrostatically transferred to the recording medium 9 conveyed at a predetermined timing in a transfer portion facing the transfer device 16. After the transfer, the photosensitive drum 12 is cleaned by removing unnecessary deposits such as toner and paper dust remaining on the surface by the elastic blade 3 of the cleaning device 17.

  The recording medium 9 onto which the toner image has been transferred is conveyed so as to be introduced into the fixing device 20, and is heated and passed when passing through the pressure contact portion between the heating rotator 22 and the pressure rotator 23 in the fixing device 20. By being pressurized, the toner image is thermally fixed to the recording medium 9. Thereafter, the sheet 9 after fixing is discharged from the fixing device 20 and is then transported to a paper discharge unit (not shown) to be stacked and accommodated. This completes the basic printing operation for one recording medium. Further, when there are a plurality of print instructions, the above-described series of operations are similarly repeated for the requested number of sheets.

  The image forming apparatus 1 employs the configuration described below in order to reduce the load received by the contact of the elastic blade 3 with the image carrier surface of the photosensitive drum 12 in the cleaning device 17.

  As shown in FIGS. 2 to 4, the elastic blade 3 in the cleaning device 17 is fixed in such a manner that the free end 31 contacts at least the image holding surface 12a of the photosensitive drum 12 and cleans the image holding surface 12a. It is installed, and at least two strain detecting elements 4 for detecting strain (deformation) are attached to the surface thereof.

  The elastic blade 3 has an end (fixed end) 32 opposite to the free end 31 fixed to a support plate 35 fixed to the housing of the cleaning device 17. As shown in FIG. 4, the elastic blade 3 is fixed to the support plate 35 so that the length (free length) L of the portion on the free end 31 side that is not fixed has a predetermined dimension. The portion of the elastic blade 3 fixed to the support plate 35 is attached in contact with the support surface of the support plate 35.

  Further, as shown in FIG. 5, the elastic blade 3 is installed with its free end 31 facing the rotational direction A of the photosensitive drum 12, and at least with respect to the image holding surface 12a of the photosensitive drum 12. At the required installation angle θ1 (angle formed with the normal line J at the contact point P of the corner 31a on the side that contacts the image holding surface 12a of the free end 31), the corner 31a on the contact side of the free end has a predetermined bite. It is installed in a slightly curved state so as to be the amount e.

  The strain detection element 4 is capable of detecting a stretched state and a contracted state with the deformation of the elastic blade 3, and specifically, a main part is constituted by a base material and a resistance element. The strain detection element 4 in this embodiment includes a first strain detection element 41 attached to the surface portion on the free end 31 side of the elastic blade 3 and a second strain detection attached to the surface portion on the fixed end 32 side. It is comprised with the element 42. FIG. The surface of the elastic blade 3 to which the strain detection elements 41 and 42 are attached is a surface on the side facing the image holding surface 12a for the purpose of increasing the detection sensitivity for the strain generated in the blade in contact with the photosensitive drum. 30.

  The fixed end 32 of the elastic blade 3 is a portion near the support plate 35 excluding the portion 33 fixed to the support plate 35. The base material of the detection element 4 is formed of a synthetic resin such as polyimide, epoxy, acrylic, or silicone, or a metal material such as stainless steel or copper. The resistance element has a resistance value of 100 to 500Ω composed of Cu—Ni alloy, Ni—Cr alloy, P-type Si, N-type Si and the like.

  Further, as shown in FIG. 6, the two strain detection elements 41 and 42 are non-images that are outside the image holding surface 12 a in the rotational axis direction (direction indicated by arrow B) of the photosensitive drum 12 in the elastic blade 3. It is attached to the surface portions 34b and 34c of the region corresponding to the holding surface regions 12b and 12c.

  Here, the area of the image holding surface 12a on the photosensitive drum 12 is, as shown in FIG. 6, the rotation axis direction of the developing roller 15a of the developing device 15 on the outer peripheral surface of the photosensitive drum 12 (the rotation of the photosensitive drum 12). This is an area portion corresponding to the development effective area D set in the same direction as the axial direction B). The non-holding surface regions 12b and 12c in this embodiment are two regions existing on both sides in the rotation axis direction B of the region of the image holding surface 12a. Since the non-holding surface regions 12b and 12c are regions outside the development effective region D of the developing roll 15a, toner for developing the electrostatic latent image does not actively adhere in the developing process. In FIG. 6, reference numerals 34 b and 24 c indicating hatched ranges are surface portions of regions corresponding to the non-image holding surface regions 12 b and 12 c of the photosensitive drum 12.

  Further, the two strain detecting elements 41 and 42 are provided on the surface portions 34b and 34c of the regions corresponding to the non-image holding surface regions 12b and 12c of the photosensitive drum 12, as shown in FIG. The drum 12 is attached at the same position in the rotation axis direction A and further away in the rotation direction B.

  As shown in FIG. 4 and the like, the first strain detection element 41 is a surface portion of the elastic blade 3 on the free end 31 side, and a required distance M from the edge portion (corner portion 31a) of the free end 31. It is attached in a state where one end portion exists at a position shifted only inward (fixed end 32 side). The distance M is, for example, 0.5 to 1.5 mm. On the other hand, the second strain detecting element 42 is attached in a state of straddling the portion 33 fixed to the support plate 35 of the elastic blade 3 and a part of the free end 31 not supported by the support plate 35. For example, the center of the detection surface of the detection element 42 exists on the boundary line with the portion 33 to which the blade 3 is fixed, or within a range of 1.5 mm closer to the free end 31 than the fixed portion 33. It is attached in a state that exists at a position shifted by.

  As shown in FIG. 7, the strain detection elements 41 and 42 are connected to a strain measurement device 45 that analyzes the detected signal and measures strain information (for example, strain amount). The strain information detected by the strain measuring device 45 is used to determine the operation content of the load reducing device 5 that performs the operation of reducing the load received by at least the contact of the elastic blade 3 with the image holding surface 12a. The load reducing device 5 performs an operation of reducing the load by using the detected strain information.

  The load reducing device 5 is configured by applying a developing device 15 as an existing product of the image forming apparatus 1. In this case, a required amount of toner is provided on at least the image holding surface 12a of the photosensitive drum 12 via the developing roll 15a of the developing device 15 and extends, for example, in the entire region or a partial region in the rotation axis direction A of the photosensitive drum. An operation of attaching the toner band in a belt-like shape (hereinafter also simply referred to as “toner band”) and supplying the toner band until it reaches the elastic blade 3 is executed as a load reducing operation. In forming the toner band, generally, a charging process by the charging device 13, an exposure process for the toner band by the exposure device 15, an operation of stopping the transfer of the toner image to the recording medium 9 by the transfer device 15 and the like are required. In this case, however, the charging device 13, the exposure device 15, and the transfer device 15 are also part of the components of the load reducing device 5.

  The load reducing device 5 is controlled by a control device 6 as load estimating means for estimating the load of the elastic blade 3 by using strain information detected by the strain measuring device 45. In other words, the load reducing device 5 performs a necessary load reducing operation according to the load of the elastic blade 3 estimated by the control device 6.

  The control device 6 includes an arithmetic processing device, a control device, a storage means (memory element, storage device, etc.) 61, an input / output device, and the like. The control device 6 is connected to the strain measuring device 45, and its detection information is input. Further, the control device 6 is connected to the load reducing device 5 and, as will be described later, according to a control program stored in advance in its storage means 61 (including calculation of the load of the elastic blade described later). In addition, the operation of the load reducing device 5 is controlled and managed.

  Hereinafter, the configuration for reducing the load on the elastic blade 3 will be described with reference to the results of a test for consideration.

In the test for consideration, the photosensitive drum 12 is an aluminum drum base having a cylindrical shape with an outer diameter of 30 mm and an axial length of 270 mm, and an axial length of 355 mm and a thickness of 19 μm or less. After forming the underlayer, from the functional separation type made of an organic photosensitive material composed of a charge generation layer (film thickness: 0.2 μm) and a charge transport layer (film thickness: 17 to 19 μm) on the surface of the undercoat layer A photosensitive layer having a protective layer (film thickness: 7 to 8 μm) formed on the surface of the photosensitive layer was used. The protective layer is a layer that is formed of, for example, a resin having a crosslinked structure and has a dynamic hardness set to 13 × 10 ⁹ N / m or more and 100 × 10 ⁹ N / m or less. Examples of the resin having a crosslinked structure include a phenolic resin, a urethane resin, and a siloxane resin having a crosslinked structure, and those having a charge transporting property are preferable.

  The elastic blade 3 is a polyurethane rubber (rubber hardness (JIS A)) having a rectangular plate shape with a thickness of 1.9 mm, a width (length in the rotational direction) of 13 mm, and an axial length of 324 mm. : 72 to 80 degrees) was used, and was fixed to a support plate 35 made of a galvanized steel plate having a L-shaped cross section and a thickness of 2 mm so that the free length (central portion) thereof was 8 mm. The elastic blade 3 was installed with respect to the photosensitive drum 12 so that the bite amount e was 1.2 mm and 1.6 mm at an installation angle θ1 of 25 °. Incidentally, the rubber material has physical properties such that the resilience modulus at a temperature of 25 ° C. is 40 to 55%, the 300% modulus is 20 MPa or more, the tensile strength is 35 kN / m or more, and the permanent elongation is 2.5% or less. It is.

  As the strain detection element 4 (41, 42), a detection element (KFG-1-120-C1-11L2M2R) manufactured by Kyowa Denki Co., Ltd. was used (thickness: length: width = 10 μm: 5 mm: 2.5 mm). As the strain measuring device 45, a strain measuring transducer (NR500 · ST04) manufactured by Keyence Corporation was used.

  One strain detection element 41 has one end of the detection element on the surface of the elastic blade 3 facing the photosensitive drum 12, and the one end of the detection element is on the fixed end 32 side from the corner 31 a of the free end 31 of the elastic blade 3. Was pasted so as to be in a state of being displaced by a distance M = 10 mm. Further, the other strain detection element 42 has a state in which the center portion of the detection surface thereof substantially coincides with the boundary line with the portion 33 fixed to the support plate 35 on the fixed end 32 side of the blade 3. Pasted on. In addition, the strain detection elements 41 and 42 at this time are attached so that the length portions thereof are along the rotation direction A of the photosensitive drum, and are spaced from the rotation direction A. (See FIG. 3).

  The second strain detecting element 42 at this time is the same position as the first strain detecting element 41 with respect to the rotational axis direction A of the photosensitive drum 12 and the same position with respect to the rotational direction A. It has become a relationship. In addition, the two strain detection elements 41 and 42 are both installed on the surface portion of the elastic blade 3 corresponding to the one non-image holding surface region 12 b of the photosensitive drum 12. Incidentally, the surface portion corresponding to (contacting with) the non-image holding surface region 12b of the elastic blade 3 at this time is a region extending from both end portions to a position 10 mm inside.

  Generally, in the elastic blade 3, the following state changes occur.

  That is, as shown in the uppermost part (left) of FIG. 8, the elastic blade 3 is at the free end 31 when not in contact with the image holding surface 12 a of the photosensitive drum 12 (when not in contact). On the other hand, since no load (load) is applied from the photosensitive drum 12, no particular deformation is caused. At this time, the elastic blade 3 is not distorted at all (refer to the left in the middle part of the figure).

  On the other hand, as shown in the uppermost part (center) of FIG. 8, the elastic blade 3 is in contact with the image holding surface 12a of the photosensitive drum 12 in a state where the rotation is stopped under a constant pressure (contact). At the time of non-rotation), a load (load) is applied to the free end 31 from the photosensitive drum 12, so that the entire free length portion is deformed. At this time, the surface 30 on the side facing the photosensitive drum 12 at the free end 31 of the elastic blade 3 is distorted in an extended state (see the center of the middle portion in the figure).

  Further, as shown in the uppermost part (right) of FIG. 8, the elastic blade 3 is in contact with the image holding surface 12a of the photosensitive drum 12 in a state of rotating in the direction of the arrow under a certain pressure (during contact: rotation). ), The corner 31a that has been in contact with the image holding surface 12a of the free end 31 is partially deformed in a state where it is caught in the rotational direction. At this time, the surface 30 at the free end 31 of the elastic blade 3 is distorted in a state in which the involved corner portion 31a is contracted from the previously extended state (see the right side of the middle step in the figure).

  Subsequently, in each elastic blade 3 installed on the photosensitive drum 12 for consideration with two kinds of biting amounts e (= 1.2 mm, 1.6 mm), the photosensitive drum 12 is stopped and fixed at a predetermined timing. The amount of distortion (waveform) obtained from the strain detection elements 41 and 42 and the strain measurement device 45 when the rotation was started at a speed of 165 mm / second was collected. The results at that time are shown in FIGS.

  FIG. 9 shows a strain result obtained from the first strain detection element 41 attached to the free end 31 side of the elastic blade 3. In this case, regarding the distortion on the free end 31 side of the elastic blade 3, the elastic blade 3 having a bite amount e of 1.6 mm has a bite amount e both when the photosensitive drum 12 is stopped and when it is rotated. Although it was larger than the case of 1.2 mm, when shifting from the stop time to the rotation time, the strain amount of any bite amount e was reduced. However, the amount of reduction was larger when the amount of biting e = 1.6 mm than when the amount of biting was 1.2 mm.

  FIG. 10 shows a strain result obtained from the second strain detecting element 42 attached to the fixed blade 32 side of the elastic blade 3. In this case, as for the strain on the fixed end 32 side of the elastic blade 3, the absolute amount of the strain is larger than the amount of strain on the free end 31 side for any biting amount e. When shifting from the stop time to the rotation time, the amount of strain hardly changed for any bite amount e.

  Next, load characteristics with respect to strain were measured using the elastic blade 3 for consideration.

  FIG. 11 shows a main part of the load measuring device 7 for the elastic blade used for the measurement. The load measuring device 7 includes a support frame 71 having a substantially L-shaped cross section, a vertically movable stage 72 that moves in a vertical direction (direction indicated by a double arrow Y), and a horizontal position that is positioned below the vertically movable stage 72. A horizontal stage 74 having a horizontal movable substrate (for example, a glass plate) 73 that moves in the direction indicated by the double arrow X, and a load that contacts the lower side of the horizontal stage 74 and is applied downward to the stage is 2 Two load transducers (compression load cell or the like) 75 received at the location are equipped, and a load meter 76 for displaying and recording the measurement result of the load transducer 75 is connected. As such a load measuring device, for example, LM-1KA manufactured by Kyowa Denki Co., Ltd. can be used.

  In the measurement, the elastic blade 3 is fixed to the vertically movable stage 72 through the support plate 35 and the mounting plate 77, while the free end 31 of the blade is at an installation angle θ1 with respect to the glass plate of the horizontal movable stage 73. Install so that it is kept in contact. The installation angle θ1 at this time was in the range of 20 to 30 °. And the measurement moved the up-and-down movable stage 72 to the direction which descends by predetermined amount, the elastic blade 3 was distorted in several steps, and the load concerning the horizontal movable stage 73 at the time of each distortion amount was investigated. Incidentally, the load applied to the elastic blade 3 at this time corresponds to the load received when contacting the photosensitive drum 12.

  As for the measurement result at this time, FIG. 12 shows the measurement result of the strain-load characteristic on the free end 31 side of the elastic blade 3, and FIG. 13 shows the measurement result of the strain-load characteristic on the fixed end 32 side of the elastic blade 3. Show. NF on the vertical axis in the figure indicates the load.

  The results indicated by the solid lines in both figures are the results when the horizontal movable substrate 73 is measured in a stationary state without being moved. In this case, the load tends to increase as the strain increases in both the free end 31 side and the fixed end 32 side of the elastic blade 3. Moreover, the result shown with a dotted line is a result when it measures in the state which moved the horizontal movable board | substrate 73 quasi-statically. In this case, in the case of the free blade 31 side of the elastic blade 3, as shown by the dotted line in FIG. 12, when the horizontal movable substrate 73 moves, the corner 31a of the free blade is rolled up (FIG. 8). (See the top right of), resulting in increased load while strain was reduced. Further, in the case of the fixed end 32 side, as shown by a dotted line in FIG. 13, the deformation does not deform like the free end 31, so that there was almost no decrease in strain, but the load increased.

  From the results shown in FIGS. 12 and 13, when the horizontal movable substrate 73 is stopped without moving on the fixed end 32 side of the elastic blade 3, the amount of change in the load is larger than that in the case of the free end 31. The strain sensitivity tends to be large. However, the fixed end 32 side is hardly deformed when the horizontal movable substrate 73 is moved and moved, and therefore, the amount of strain hardly changes. Therefore, the strain sensitivity with respect to the load change (ΔNF) There is almost no correlation. On the other hand, on the free end 31 side of the elastic blade 3, when the horizontal movable substrate 73 is moved and moved, the strain sensitivity to the load change (ΔNF) tends to be larger than that of the fixed end 32. It is in. However, on the free end 31 side, when the horizontal movable substrate 73 is stopped without moving, the sensitivity of strain with respect to the change in load tends to be small as compared with the case of the fixed end 32.

  From this, the load of the elastic blade 3 (in other words, the load from the photosensitive drum) is estimated from the amount of strain on the fixed end 32 side when stationary (when the photosensitive drum 12 is not rotating). When moving (when the photosensitive drum 12 rotates), the load estimated when the stationary end 32 is stationary corresponds to the amount of change in the amount of strain when the free end 31 is stationary from when stationary. The load obtained by adding the change in load was set to be estimated. If the load of the elastic blade 3 is estimated in this way, a result close to the load (state) actually generated by the elastic blade 3 can be obtained.

  Therefore, in this embodiment, when estimating the load (load) of the elastic blade 3, the load NF when the photosensitive drum 12 is stopped without rotating (non-rotating) is expressed by the following equation (a The load DNF when the photosensitive drum 12 is rotating (during rotation) is calculated by the following equation (b).

  NF = αS0 (a)

  DNF = NF + β (S2-S1) (b)

  The symbol S0 in the formula (a) is the amount of strain on the fixed end 32 side of the elastic blade 3 at the time of non-rotation, and α represents the slope (load coefficient) in the strain-load characteristic (approximate line) shown in FIG. . In the formula (b), S1 is the amount of strain on the free end 31 side of the elastic blade 3 when not rotating, S2 is the amount of strain on the free end 31 side of the elastic blade 3 when rotating, and β is shown in FIG. The inclination (load coefficient) in the strain-load characteristic (approximate line) is shown.

  When estimating the load (load) of the elastic blade 3 in the image forming apparatus 1, when the image forming operation start command is received, the fixed end of the elastic blade 3 is in a stage when the photosensitive drum 12 is not rotated. 32 side strain amount: S0 and free end 31 side strain amount: S1 are respectively detected and measured from the first strain detecting element 41 and the second strain detecting element 42, and the results (S0, S1) are measured, for example. It is stored and held in storage means (memory element or the like) included in the strain measuring device 45. Next, when the image forming operation is executed, the strain amount S2 on the free end 31 side of the elastic blade 3 is detected from the second strain detecting element 42 and measured, and the result (S2) is stored in the same manner. Hold it. On the other hand, the above-described load coefficients α and β are obtained from the measurement results of the strain-load characteristics described above, and the data are similarly stored and held. Each of these data (S0, S1, S2, α, β) may be stored in a storage unit (memory element, storage device, etc.) 61 in the control device 6.

  Then, in the control device 6, the data (S 0, S 1, S 2, α, β) are substituted into the calculation formulas (a) and (b) and processed, so that the elastic blade 3 is not rotated. The load NF and the load DNF during rotation are set to be obtained. That is, the load NF (load) when the elastic blade 3 is not rotating is calculated using the equation (a) from the strain amount S0 on the fixed end 32 side when not rotating (see the center of the lowermost stage in FIG. 8). . Further, the load DNF (load) during rotation of the elastic blade 3 is the load NF during non-rotation and the load change (ΔNF) calculated from the change in strain amount on the free end 31 side (S2-S1). Calculation is made using the formula (b) with the content of addition (see the right at the bottom of FIG. 8).

In FIG. 14, the load (load) DNF at the time of rotation of the elastic blade 3 for consideration with respect to the photosensitive drum 12 was calculated by the strain detecting elements 41 and 42, the strain measuring device 45, and the control device 6 according to the procedure described above. This is sometimes the result. At this time, α = 2.5 × 10 ⁻² [10 ⁶ gf / mm] and β = 0.2 [10 ⁶ gf / mm].

  In FIG. 14, the load DNF during non-rotation increases when the bite amount e is larger (e = 1.6 mm), and the load DNF during rotation increases as the bite amount e increases and decreases (e = 1). It can be seen that the difference in load with .2 mm) also tends to be wider than the difference during non-rotation.

  FIG. 15 shows a case where the photosensitive drum 12 and the elastic blade 3 for consideration are mounted on the image forming apparatus 1, and the frequency is applied to the charging roll 13 a in the charging device 13 as an AC component of the charging voltage (DC voltage: −750 V). The result of measuring the amount of strain on the free end 31 side of the elastic blade 3 (obtained by the strain measuring device 45) when applying an alternating current whose effective value was gradually increased from 1.3 mA to 2.0 mA at 1200 Hz. Value).

  In FIG. 15, when the amount of distortion of the elastic blade 3 with the bite amount e = 1.6 mm is rotated when the photosensitive drum 12 is rotated, the effective value of the alternating current of the charging voltage is gradually decreased and the effective value thereof is increased. It is shown that the magnitude relationship is reversed in the course of ascending by becoming smaller than the strain amount of the elastic blade 3 with the biting amount e = 1.2 mm. That is, the strain amount on the free end 31 side of the elastic blade 3 tends to fluctuate when there is a component (in this case, the charging roll 13a) to which an AC voltage is present that is close to the elastic blade 3. It can be seen that it is difficult to accurately determine the load (DNF) from the amount of strain (S2). It has been confirmed that the amount of strain on the fixed end 32 side of the elastic blade 3 does not vary due to the difference in the execution value of the alternating current.

  Therefore, in this embodiment, as a countermeasure, a high frequency filter 49 is installed in the detection (electronic) circuit 46 of the strain measuring device 45 as shown in FIG. The high frequency filter 49 was installed at the input part of the signal from the strain detection elements 41 and 42 of the detection circuit 46. Further, as the high frequency filter 49, a high frequency removal filter capable of removing at least the frequency component of the AC voltage in the charging voltage was used. Specifically, for example, an LC filter capable of removing frequencies of 100 to 1000 Hz or more (L: a filter using a change in resistance value depending on the frequency of the coil and C: capacitor) was applied.

  In this image forming apparatus 1, the information on the load (NF, DNF) that is the load of the elastic blade 3 calculated as described above is used to develop the photosensitive drum 12 from the developing device 15 as the load reducing device 5. The required toner band described above was prepared, and the toner in the band was supplied so as to reach the elastic blade 3.

  FIG. 16 shows the control content related to the load reducing device 5 and the like by the control device 6 at this time. FIG. 17 shows a setting correspondence table (LUT: lookup table) regarding the amount (width: length in the rotation direction A) of the toner band with respect to the load (load) DNF of the elastic blade 3 and the band formation interval.

  As shown in FIG. 16, in the image forming apparatus 1, when the printing operation as described above is executed (step 10: S 10), the strain amount (S 0, S 1, S 2) of the elastic blade 3 is the strain detection element 4. And it is measured by the strain detection means of the strain measuring device 45 (S11). Then, during the printing operation, it is determined whether or not the count value N1 of the number of prints (band PV) for the formation interval (interval) for forming the toner band is equal to or greater than the prescribed number B of the band interval (S12). ), If N1 is equal to or greater than the prescribed number B, a toner band is formed (S13).

  The toner band is formed as a toner band having a predetermined width when toner is supplied to and adhered to the photosensitive drum 12 from the developing roll 15a of the developing device 15 as the load reducing device 5. For the width of the toner band at this time, the minimum value (for example, 10 mm) that is initially set or the latest setting value that is stored and held in the storage unit first is applied. The toner band is, for example, a rectangular having a required width (for example, 10 to 40 mm) and a predetermined density (25 to 100%) over the entire image holding surface 12a in the rotation axis direction B of the photosensitive drum 12 charged by the charging device 13. A latent image having a shape was formed by the exposure device 13, and the latent image was developed by the developing device 15. At this time, the transfer device 16 is set so that the transfer voltage is not applied or a voltage having a polarity opposite to the charging polarity of the toner is applied so that the toner in the toner band is not transferred to the recording medium 9 or the like. did.

  The toner in the toner band reaches the elastic blade 3 as the photosensitive drum 12 rotates, and exists between the photosensitive drum 12 and functions as a lubricant. The toner in the toner band that reaches the elastic blade 3 is present in a portion 34a (see FIG. 6) corresponding to the image holding surface, and spreads so as to move in the rotation axis direction B of the photosensitive drum 12 to hold the non-image. It exists also in the opposing part 34b, 34c with a surface. As a result, the coefficient of friction between the elastic blade 3 and the photosensitive drum is reduced, and as a result, occurrence of problems such as turning up of the elastic blade and wear of the photosensitive drum 12 is reduced.

  After the toner band is formed, the count N1 of the band PV is reset and the load (DNF) of the elastic blade 3 stored in the storage unit is reset (S14). In step S12, if N1 is less than the prescribed number B, the count value N1 of the band PV is updated to a value obtained by adding the number of prints in the printing operation without forming a toner band (S20).

  Subsequently, the load (load) DNF when the elastic blade 3 is rotated is calculated and calculated with the above-described content using the strain amount measured in the control device 6 (S15).

  It is determined whether or not the latest load DNF obtained at this time is greater than the storage load (storage DNF) stored in the storage means (S16). At this time, if the latest load DNF is larger, the data of the latest load DNF is inserted into the storage area M of the recording means to replace the old DNF data (S17), and according to the latest load DNF. The toner band amount and the prescribed number B of intervals are determined by correcting the setting contents with reference to the setting correspondence table (LUT) shown in FIG. 17 (S18). If the latest load DNF is less than or equal to the stored DNF in step 16, the storage data is not replaced or the conditions regarding the toner band are not determined (reviewed).

  Finally, it is determined whether or not a subsequent print operation (job) start command has been received (S19). If there is a next print operation command, the control operation described above is repeated in the same manner.

<Evaluation test>
Hereinafter, an evaluation test regarding the presence / absence of turning of the elastic blade 3 and the amount of wear of the photosensitive drum, performed using the image forming apparatus 1 including a strain detection element, a load reduction device, and the like will be described.

  In this evaluation test, the photosensitive drum for consideration was used as the photosensitive drum 12, and the photosensitive drum 12 was set to rotate at a rotation speed of 165 mm / sec. For the charging device 13, a voltage in which alternating current (alternating current frequency: 1200 Hz, effective current value: 1.5 mA) is superimposed on direct current is applied as a charging voltage, and the image holding surface 12 a of the photosensitive drum is charged to −700 V. Was set to let The exposure device 14 was set to form an electrostatic latent image having a solid portion potential of −300 V and an image density of 5%. For the developing device 15, a two-component developer containing a non-magnetic toner having an average particle diameter of 5.8 μm and a magnetic carrier having an average particle diameter of 30 μm is used as the developer, and a direct current (−600 V) is used as a developing voltage. It was set to apply a voltage superimposed (frequency of alternating current: 6000 Hz, voltage: -150 to -400 V, voltage amplitude: 900 V). The basic image forming apparatus 1 is manufactured based on a Fuji Xerox printer (DocuCenterClor a450).

  The cleaning device 17 is configured by installing the elastic blade 3 for consideration under the same conditions (the amount of biting e is two types). Moreover, about the strain detection elements 41 and 42, the same kind as the case for the said consideration was attached on the same conditions. As the strain detector 45, the same type as in the case of the above discussion was used. The detection circuit 46 of the detection device 45 includes a high frequency filter 49 that removes a high frequency of 200 Hz in order to prevent erroneous detection due to an alternating current in the charging voltage applied to the charging roll 13a located closest to the cleaning device 17. Attached. Further, the load reducing device 5 (developing device 15 or the like) is set to execute an operation for reducing the load of the elastic blade 3 based on the control procedure (FIG. 16) and the operation condition (FIG. 17) described above. .

  Two types of image forming apparatuses 1 that differ only in the amount of biting e of the elastic blade 3 are used to print A4 (JIS) paper as a single printing operation (job) in a high temperature and high humidity environment of 28 ° C. and 85% RH. The operation of forming the image was performed on five of the nine sheets, and this printing operation was performed until the total number of printed sheets reached 50000 sheets.

  After completion of all the printing operations, the image forming apparatus 1 was observed for the occurrence of turning of the elastic blade 3 and the amount of wear of the surface protective layer of the photosensitive drum 12 was measured. For the measurement of the amount of wear, a film thickness measuring machine applying the principle of line spectral interference was prototyped, and the film thickness of the photosensitive drum was measured by the measuring machine. The measuring machine makes white light incident on the image holding surface of the photoconductive drum as a measurement sample, guides the multiple reflected light from the image holding surface to the spectroscope through the objective lens, and records it on the image sensor (CCD, etc.). After that, the recorded data is analyzed such that the spectrum of each wavelength is analyzed by FFT (Discrete Fourier Transform) with a computer so that the film thickness can be obtained.

  The measurement result of the amount of wear is shown in FIG. The amount of wear in the figure is the difference between the film thicknesses in the rotation axis direction B before and after the test and is shown as the amount of wear per 1000 revolutions (kCyc) of the photosensitive drum 12. Further, ranges of about 0 to 30 mm and 330 to 355 mm as positions in the rotation axis direction B are regions corresponding to the non-image holding surfaces 34b and 34c (see FIG. 6).

  As for the presence or absence of turning-up, as another test, the photosensitive drum 12 was rotated at a speed of 165 mm / second in an environment of a temperature of 25 ° C. and a humidity of 85%, and the alternating current of the charging voltage was changed. When a test print operation for forming a toner image with an image density of 1% by applying a voltage with an effective value of 2.3 mm and charging is performed, the elastic blade 3 with a bite e = 1.6 mm is turned up. I investigated. As a result, the elastic blade 3 was not turned up even after the photosensitive drum 12 was rotated 10,000 times.

  For comparison, an image forming apparatus having the following configuration was prepared, and the above-described evaluation test was performed under the same conditions. The image forming apparatus (comparative example) has a substantially central portion of a region 34a (see FIG. 6) corresponding to the image holding surface region of two types (e = 1.2 mm, 1.6 mm) of elastic blades 3 having different biting amounts e. A strain detecting element 41 is provided at a position on the free end 31 side (position shifted 1 mm inward from the corner 31a).

  The measurement result of the amount of wear in this comparative example is shown in FIG. Further, regarding the presence or absence of the occurrence of turning of the elastic blade 3 in the comparative example, the same test as the above-described test was performed, and it was confirmed that the turning of the elastic blade 3 occurred when the photosensitive drum 12 rotated 2000 times. .

[Other Embodiments]
In the above embodiment, the strain detection elements 41 and 42 are attached to one region 34b (FIG. 6) of the elastic blade 3 corresponding to the non-image holding surfaces 12b and 12c of the photosensitive drum. It can also be configured to be attached to the region 34c. Further, the strain detection elements 41 and 42 may be arranged at positions shifted in the rotation axis direction B of the photosensitive drum as long as they are in the regions 34b and 34c corresponding to the non-image holding surface. In addition, the strain detection elements 41 and 42 can be configured to be attached to positions on the free end 31 side and the fixed end 32 side of the region 34a corresponding to the image holding surface 12a of the photosensitive drum in the elastic blade 3. It is.

  The load coefficients α and β used when calculating the load of the elastic blade 3 are determined for each image forming apparatus 1 (cleaning device 17) in consideration of the tolerance of the elastic blade 3 itself and the variation tolerance of its attachment. Measure the strain-load characteristics of the elastic blade 3 attached to the product before shipping the product to confirm the load factors α and β, respectively, and store the load factors α and β as calibration data (official data) It is also possible to face each other so as to store again.

  Further, the high-frequency filter 49 installed in the detection circuit of the strain measuring device 35 not only removes the adverse effect due to the frequency of the alternating current in the charging voltage applied by the charging device 13 but also, for example, a position near the cleaning device 17. From the viewpoint of removing the adverse effect due to the frequency of the alternating current in the developing voltage applied by the developing device 15 installed in the above, they can be installed together or independently.

  In the above-described embodiment, the case where the developing device 15 is applied as the load reducing device 5 is exemplified. However, the load reducing device 5 is not limited to a configuration using an existing product, and for example, toner, lubrication, etc. It is also possible to configure a dedicated device capable of supplying the agent or the like around the photosensitive drum 12. For example, a coating device for applying a lubricant such as zinc stearate is disposed at a position upstream of the rotational direction A of the photosensitive drum 12 of the cleaning device 17 elastic blade 3. In the load reducing device 5 including this lubricant application device, the image forming operation is interrupted, and the photosensitive drum 12 is idly rotated to apply the lubricant.

  In addition, as the load reducing device 5 configured to use an existing product, for example, in the case of an image forming apparatus that uses an intermediate transfer member, the image forming operation is interrupted, and the photosensitive drum 12 and the intermediate member are intermediated. The transfer body is idled without being charged, and a speed difference of about 3 to 15% is provided between the two. In this case, the image holding surface of the photosensitive drum is polished by the rubbing action due to the speed difference, and the discharge product adhering to the drum surface is removed to reduce the friction coefficient of the drum surface. it can.

  Furthermore, the cleaning device 17 in which the strain detection element or the like is installed is not limited to the cleaning device for the photosensitive drum 12, but can be used as a cleaning device for other components (for example, an intermediate transfer member). In this case as well, it may be configured to be equipped with a load reducing device or the like. The cleaning member to be brought into contact with an object to be cleaned such as a photosensitive drum is not limited to a rubber elastic blade having a flat plate shape, but also a metal thin plate such as stainless steel, phosphor bronze, magnesium alloy (in this case, For example, a thickness of 50 to 150 μm and a free length of 6 to 12 mm are set.

  In addition, in the above-described embodiment, the type of image forming apparatus that forms a single color toner image is exemplified. However, the type that forms a color toner image (multicolor image) composed of a plurality of colors of toner is illustrated. Needless to say, this image forming apparatus can be applied. Further, the image forming apparatus may employ an intermediate transfer method.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 3 ... Elastic blade (cleaning member)
4 ... Strain detection element (part of strain detection means)
5 ... Load reduction device (load reduction means)
6 ... Control device (load estimation means)
12 ... Photosensitive drum (image carrier)
12a ... Image holding surface 31 ... Free end 32 ... Fixed end 41 ... First strain detecting element (first strain detecting means)
42 ... Second strain detecting element (second strain detecting means)
45 ... Strain measuring device (part of strain detecting means)
46 ... Detection circuit 49 ... High frequency filter A ... Rotational direction B ... Rotational axis direction

Claims (7)

An image carrier having an image holding surface for holding the image and rotating;
A plate-like cleaning member installed in a state where the free end is in contact with at least the image holding surface of the image holding body and is fixed so as to clean the image holding surface;
Strain detecting means for detecting strain of the cleaning member;
Load reducing means for performing an operation of reducing a load received by contact with at least the image holding surface of the cleaning member using information on distortion detected by the distortion detecting means;
The strain detecting means is composed of a first strain detecting means attached to the surface portion on the free end side of the cleaning member and a second strain detecting means attached to the surface portion on the fixed end side. An image forming apparatus. The cleaning member is installed in contact with the non-image holding surface area that is outside the image holding surface in the rotation axis direction of the image holding body,
The image forming apparatus according to claim 1, wherein the first and second strain detection units are attached to a surface portion of an area corresponding to a non-image holding surface area of the image holding body of the cleaning member.   3. The image forming apparatus according to claim 1, wherein the first and second strain detection units are attached at the same position in the rotation axis direction of the image carrier and at a position away from the rotation direction. 4.   The load reducing means includes load estimating means for estimating the load of the cleaning member using information on strain detected by the strain detecting means, and an actual load according to the load estimated by the load estimating means. The image forming apparatus according to claim 1, wherein the image forming apparatus executes an operation for reducing the image quality. The load estimation unit calculates a non-rotation load based on a non-rotation strain amount detected by the second strain detection unit when the image carrier is not rotated.
In addition, when the image carrier is rotated, the amount of non-rotation distortion detected by the first distortion detection unit during non-rotation is determined from the amount of rotation distortion detected by the first strain detection unit. 5. The image forming apparatus according to claim 4, wherein a load change calculated based on a strain change amount obtained by dividing the load is calculated as an amount added to the non-rotation load as a rotation load. .   The load estimation means actually measures the load characteristic with respect to the amount of strain at the time of non-rotation in the cleaning member, obtains a load coefficient and holds it in the storage means, and the load coefficient is stored in the strain at the time of non-rotation or rotation. The image forming apparatus according to claim 5, wherein a value obtained by multiplying the amount is calculated as a non-rotating or rotating load. A charging device or a developing device for applying an alternating voltage is disposed around the image holding member, and the strain detecting means has a detection circuit for detecting the amount of strain,
The image forming apparatus according to claim 5, wherein a frequency filter for removing at least a frequency component of an AC voltage applied to the charging device or the developing device is installed in the detection circuit.

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