Image forming device

Abstract

To provide an image forming apparatus that can detect a contact force of a cleaning member with a simple configuration.SOLUTION: An image forming apparatus is an image forming apparatus comprising an image carrier that carries a toner image and a cleaning member that is in contact with and cleans a surface of the image carrier, and comprises a control unit that performs measurement control of rotating the image carrier while supplying toner to the image carrier, thereby measuring a parameter related to a contact force of the cleaning member with the image carrier.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] In an electrophotographic image forming apparatus, a cleaning member (e.g., a blade member) is brought into contact with the surface of an image carrier (e.g., a photosensitive drum, etc.) that carries a toner image, thereby removing residual toner and other deposits that have adhered to the surface of the image carrier.

[0003] In recent years, there has been a demand for highly reliable and long-life image forming units (e.g., photosensitive units, etc.). The life of an image forming unit is determined mainly by image defects due to wear of the image carrier and poor cleaning caused by wear of the cleaning member.

[0004] The wear rate of the image carrier and the cleaning member depend on the contact force of the cleaning member on the image carrier. As the contact force of the cleaning member increases, the above speeds also increase. Therefore, if the contact force of the cleaning member can be properly managed, the reliability of the image forming unit can be improved by detecting the end of the image forming unit's life and adjusting the contact force of the cleaning member.

[0005] For example, Patent Documents 1 and 2 disclose a configuration in which polarized light is incident on a cleaning member to measure the internal stress of the cleaning member. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-189327 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-5580 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the configurations described in Patent Documents 1 and 2 are complicated, including a light source, a polarizer, an analyzer, and an observation device, and therefore have room for improvement in terms of the configuration for detecting the state (contact force) of the cleaning member.

[0008] SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that is capable of detecting the contact force of a cleaning member with a simple configuration. [Means for solving the problem]

[0009] The image forming apparatus according to the present invention comprises: An image forming apparatus including an image carrier that carries a toner image, and a cleaning member that comes into contact with and cleans the surface of the image carrier, a control unit that performs measurement control to measure a parameter related to the contact force of the cleaning member on the image carrier by rotating the image carrier while supplying toner to the image carrier during non-image formation; and, a charging roller for charging the image carrier; Equipped with 、 The parameter is the amount of change in charging current between the image carrier and the charging roller. . [Effects of the Invention]

[0010] According to the present invention, the contact force of the cleaning member can be detected with a simple configuration. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram illustrating a main part of a control system of the image forming apparatus. [Figure 3] FIG. 10 is a diagram showing the relationship between the number of rotations of the photosensitive drum and the amount of change in charging current. [Figure 4] FIG. 10 is a diagram showing the relationship between the contact force of the cleaning member and the wear rate of the photosensitive drum. [Figure 5]FIG. 10 is a diagram showing the relationship between the film thickness of the photosensitive drum and the charging current. [Figure 6] FIG. 10 is a diagram showing the relationship between the rotation speed of the photosensitive drum and the measured value of the charging current. [Figure 7A] FIG. 10 is a diagram showing the relationship between the number of printed sheets and the contact force of the cleaning member. [Figure 7B] FIG. 4 is a diagram illustrating a contact portion between the photosensitive drum and the cleaning member. [Figure 8] FIG. 10 is a diagram showing the relationship between the amount of supplied toner and the contact force of the cleaning member. [Figure 9A] 10 is a diagram showing the relationship between the contact force of the cleaning member and the amount of change in temperature of the photosensitive drum. FIG. [Figure 9B] FIG. 4 is a diagram illustrating an example of the arrangement of a temperature detection unit. [Figure 10A] 10 is a diagram showing the relationship between the contact force of the cleaning member and the amount of distortion of the cleaning member. FIG. [Figure 10B] FIG. 10 is a diagram showing an example of the arrangement of strain gauges. [Figure 11] FIG. 10 is a diagram showing the relationship between the amount of toner patch and the amount of distortion of the cleaning member. [Figure 12A] FIG. 10 is a diagram showing the relationship between the output voltage of the distance sensor and the contact force of the cleaning member. [Figure 12B] FIG. 10 is a diagram illustrating an example of the arrangement of distance sensors. [Figure 13A] 10A and 10B are diagrams illustrating an example of the positional relationship between a biasing member and an imaging unit. [Figure 13B] 10A and 10B are diagrams illustrating the relationship between the length of the urging member and the contact force of the cleaning member. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a diagram showing a schematic overall configuration of an image forming apparatus 1 according to an embodiment of the present invention. Fig. 2 is a diagram showing the main parts of a control system of the image forming apparatus 1.

[0013] 1, image forming apparatus 1 is an intermediate transfer type color image forming apparatus that utilizes electrophotographic process technology. That is, image forming apparatus 1 primarily transfers toner images of each color (Yellow, M, C, and K) formed on photosensitive drum 413 onto intermediate transfer belt 421, and then superimposes the four color toner images on intermediate transfer belt 421, and then secondarily transfers the images onto paper S sent from paper feed tray units 51a to 51c, thereby forming an image.

[0014] In addition, the image forming apparatus 1 employs a tandem system in which photosensitive drums 413 corresponding to the four colors YMCK are arranged in series in the running direction of the intermediate transfer belt 421, and each color toner image is transferred sequentially to the intermediate transfer belt 421 in a single step.

[0015] As shown in FIG. 2, the image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a paper conveying unit 50, a fixing unit 60, and a control unit 101.

[0016] The control unit 101 includes a CPU (Central Processing Unit) 102, a ROM (Read Only Memory) 103, a RAM (Random Access Memory) 104, etc. The CPU 102 reads a program corresponding to the processing content from the ROM 103, loads it into the RAM 104, and works with the loaded program to centrally control the operation of each block of the image forming apparatus 1. At this time, various data stored in the storage unit 72 is referenced. The storage unit 72 is configured, for example, with a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive.

[0017] The control unit 101 transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 71. The control unit 101 receives, for example, image data (input image data) transmitted from an external device, and forms an image on a sheet S based on this image data. The communication unit 71 is configured, for example, by a communication control card such as a LAN card.

[0018] As shown in FIG. 1, the image reading unit 10 includes an automatic document feeder 11 called an ADF (Auto Document Feeder), an original image scanning device 12 (scanner), and the like.

[0019] The automatic document feeder 11 transports the documents D placed on the document tray using a transport mechanism and sends them to the document image scanning device 12. The automatic document feeder 11 makes it possible to continuously read the images (including both sides) of multiple documents D placed on the document tray all at once.

[0020] The document image scanning device 12 optically scans a document transported onto the contact glass from the automatic document feeder 11 or a document placed on the contact glass, and forms an image of the light reflected from the document on the light receiving surface of a CCD (Charge Coupled Device) sensor 12a to read the document image. The image reading unit 10 generates input image data based on the reading result by the document image scanning device 12. This input image data is subjected to predetermined image processing in the image processing unit 30.

[0021] 2, the operation display unit 20 is configured, for example, by a liquid crystal display (LCD) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, image states, operation statuses of various functions, etc., in accordance with a display control signal input from the control unit 101. The operation unit 22 has various operation keys such as a numeric keypad and a start key, and accepts various input operations by the user and outputs operation signals to the control unit 101.

[0022] The image processing unit 30 includes a circuit for performing digital image processing according to initial settings or user settings. For example, under the control of the control unit 101, the image processing unit 30 performs gradation correction based on gradation correction data (gradation correction table). In addition to gradation correction, the image processing unit 30 also performs various correction processes such as color correction and shading correction, as well as compression processing. The image forming unit 40 is controlled based on the image data that has undergone these processes.

[0023] 1, the image forming unit 40 forms an image on a sheet S based on the settings of a print job. The image forming unit 40 includes image forming units 41Y, 41M, 41C, and 41K, an intermediate transfer unit 42, and the like, for forming images using color toners of Y, M, C, and K components based on input image data.

[0024] The image forming units 41Y, 41M, 41C, and 41K for the Y, M, C, and K components have the same configuration. For ease of illustration and explanation, common components are denoted by the same reference numerals, and when distinguishing between them, the reference numerals are suffixed with Y, M, C, or K. In Figure 1, only the components of the image forming unit 41Y for the Y component are denoted by reference numerals, and the components of the other image forming units 41M, 41C, and 41K are not denoted by reference numerals.

[0025] The image forming unit 41 includes an exposure device 411, a developing device 412, a photosensitive drum 413, a charging device 414, a drum cleaning device 415, a current detection unit 416, and the like.

[0026] Photosensitive drum 413 is made of an organic photosensitive body in which a photosensitive layer made of a resin containing an organic photoconductor is formed on the outer peripheral surface of a drum-shaped metal substrate, for example.

[0027] The control unit 101 controls the drive current supplied to a drive motor (not shown) that rotates the photosensitive drum 413, thereby rotating the photosensitive drum 413 at a constant peripheral speed.

[0028] The charging device 414 is a charging roller that comes into contact with the photosensitive drum, and generates a corona discharge to uniformly charge the surface of the photosensitive drum 413, which has photoconductivity, to a negative polarity.

[0029] The exposure device 411 is configured with, for example, a semiconductor laser, and irradiates the photosensitive drum 413 with laser light corresponding to an image of each color component. As a result, an electrostatic latent image of each color component is formed in the image area on the surface of the photosensitive drum 413 irradiated with the laser light due to the potential difference with the background area.

[0030] The developing device 412 is a two-component reverse type developing device, and visualizes the electrostatic latent image by depositing the developer of each color component onto the surface of the photosensitive drum 413, thereby forming a toner image.

[0031] To the developing device 412, for example, a DC developing bias having the same polarity as the charging polarity of the charging device 414, or a developing bias in which an AC voltage is superimposed with a DC voltage having the same polarity as the charging polarity of the charging device 414, is applied. As a result, reversal development is performed in which toner adheres to the electrostatic latent image formed by the exposure device 411.

[0032] The drum cleaning device 415 is in contact with the surface of the photosensitive drum 413 and has a flat cleaning member 417 (drum cleaning blade) made of an elastic material, and removes toner remaining on the surface of the photosensitive drum 413 without being transferred to the intermediate transfer belt 421.

[0033] Furthermore, when no image formation is being performed, the control unit 101 performs estimation control to estimate the contact force of the cleaning member 417 on the photosensitive drum 413. Details of the estimation control performed by the control unit 101 will be described later.

[0034] Current detection unit 416 is a measuring device capable of measuring the current (hereinafter referred to as charging current) flowing between charging device 414 and photosensitive drum 413. Current detection unit 416 counts up each time the charging current changes by a predetermined value while photosensitive drum 413 is rotating.

[0035] The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, a belt cleaning device 426, and the like.

[0036] The intermediate transfer belt 421 is an endless belt that is stretched around a plurality of support rollers 423 in a loop shape. At least one of the support rollers 423 is a drive roller, and the others are driven rollers. For example, it is preferable that roller 423A, which is disposed downstream of primary transfer roller 422 for the K component in the belt running direction, be the drive roller. This makes it easier to maintain a constant running speed of the belt in the primary transfer section. As drive roller 423A rotates, intermediate transfer belt 421 runs at a constant speed in the direction of arrow A.

[0037] The intermediate transfer belt 421 is a conductive and elastic belt having a high resistance layer on its surface. The intermediate transfer belt 421 is driven to rotate by a control signal from the control unit 101.

[0038] Primary transfer rollers 422 are disposed opposite photosensitive drums 413 of each color component on the inner peripheral side of intermediate transfer belt 421. Primary transfer rollers 422 are pressed against photosensitive drums 413 with intermediate transfer belt 421 sandwiched therebetween, thereby forming a primary transfer nip for transferring a toner image from photosensitive drum 413 to intermediate transfer belt 421.

[0039] Secondary transfer roller 424 is disposed on the outer circumferential surface side of intermediate transfer belt 421, facing backup roller 423B, which is disposed downstream of drive roller 423A in the belt running direction. By sandwiching intermediate transfer belt 421 between secondary transfer roller 424 and backup roller 423B, a secondary transfer nip for transferring a toner image from intermediate transfer belt 421 to paper S is formed.

[0040] When intermediate transfer belt 421 passes through the primary transfer nip, the toner images on photosensitive drum 413 are sequentially superimposed and primarily transferred onto intermediate transfer belt 421. Specifically, a primary transfer bias is applied to primary transfer roller 422, and a charge of the opposite polarity to the toner is applied to the back side of intermediate transfer belt 421, that is, the side that contacts primary transfer roller 422, so that the toner images are electrostatically transferred onto intermediate transfer belt 421.

[0041] Thereafter, when the paper S passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred onto the paper S. Specifically, a secondary transfer bias is applied to the secondary transfer roller 424, and a charge of the opposite polarity to the toner is applied to the back side of the paper S, that is, the side that abuts the secondary transfer roller 424, so that the toner image is electrostatically transferred onto the paper S. The paper S with the transferred toner image is transported towards the fixing unit 60.

[0042] The belt cleaning device 426 removes the residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer.

[0043] The fixing section 60 includes an upper fixing section 60A having a fixing surface side member arranged on the fixing surface of the paper S, i.e., the surface on which the toner image is formed, a lower fixing section 60B having a back surface side support member arranged on the back surface of the paper S, i.e., the surface opposite the fixing surface, and a heating source, etc. When the back surface side support member is pressed against the fixing surface side member, a fixing nip is formed that clamps and transports the paper S.

[0044] The fixing unit 60 fixes the toner image onto the paper S by applying heat and pressure to the paper S, which has been transported after the toner image has been secondarily transferred, at a fixing nip. The fixing unit 60 is disposed as a unit inside the fixing device F.

[0045] Upper fixing section 60A has an endless fixing belt 61, which is a fixing surface side member, a heating roller 62, and a fixing roller 63. Fixing belt 61 is stretched between heating roller 62 and fixing roller 63.

[0046] The lower fixing section 60B has a pressure roller 64 which is a back surface support member. The pressure roller 64 forms a fixing nip between the pressure roller 64 and the fixing belt 61 to sandwich and transport the paper S.

[0047] The paper transport section 50 includes a paper feed section 51, a paper discharge section 52, and a transport path section 53. The three paper feed tray units 51a to 51c that make up the paper feed section 51 store paper S (standard paper, special paper) identified based on basis weight, size, etc., by pre-set type.

[0048] The transport path section 53 has a plurality of transport roller pairs such as a registration roller pair 53a, a normal transport path 53b that passes the paper S through the image forming section 40 and the fixing section 60 and discharges it outside the image forming apparatus 1, and the like.

[0049] The sheets S stored in the sheet feed tray units 51a to 51c are fed one by one from the top and transported to the image forming unit 40 by the transport path unit 53. In the image forming unit 40, the toner images on the intermediate transfer belt 421 are secondarily transferred all at once onto one side of the sheets S, and a fixing process is performed in the fixing unit 60. The sheets S with the images formed thereon are discharged outside the apparatus by the sheet discharge unit 52 equipped with the sheet discharge rollers 52a.

[0050] Next, the estimation control of the contact force of the cleaning member 417 by the control unit 101 will be described.

[0051] Drum cleaning device 415 performs a cleaning operation to remove toner remaining on the surface of photosensitive drum 413, but because cleaning member 417 is in contact with photosensitive drum 413, photosensitive drum 413 and cleaning member 417 wear out. As these wear out, image defects occur due to improper cleaning of photosensitive drum 413, and the image forming unit reaches the end of its life.

[0052] Therefore, it is necessary to appropriately manage the contact force of cleaning member 417 on photosensitive drum 413. If the contact force of cleaning member 417 can be appropriately managed, it becomes possible to appropriately detect the life of the image forming unit and appropriately adjust the contact force of cleaning member 417, thereby improving the reliability of the image forming unit.

[0053] In the present embodiment, the control unit 101 performs estimation control of the contact force of the cleaning member 417, thereby making it possible to appropriately manage the contact force of the cleaning member 417. Specifically, the control unit 101 performs measurement control to measure parameters related to the contact force of the cleaning member 417 on the photosensitive drum 413 by rotating the photosensitive drum 413 while supplying toner to the photosensitive drum 413. Then, the control unit 101 estimates the contact force of the cleaning member 417 based on the measurement results (parameters) of the current detection unit 416 during the measurement control.

[0054] It has been confirmed that the amount of change in charging current between charging device 414 and photosensitive drum 413, detected by current detection unit 416, increases as the rotation speed of photosensitive drum 413 increases. Fig. 3 is a diagram showing the relationship between the rotation speed of photosensitive drum 413 and the amount of change in charging current. Fig. 3 shows the amount of change in charging current when photosensitive drum 413 is rotated while a fixed amount of toner (10 mg of toner per sheet of paper) is supplied to photosensitive drum 413.

[0055] It can be seen from FIG. 3 that the greater the contact force of the cleaning member 417, the greater the amount of change in the charging current.

[0056] 4, it has been confirmed that the greater the contact force of cleaning member 417, the greater the wear rate of photosensitive drum 413. Furthermore, as shown in Fig. 5, it has been confirmed that the greater the film thickness of photosensitive drum 413, the smaller the charging current. In other words, it has been confirmed that there is a relationship in which the charging current increases as photosensitive drum 413 wears and the film thickness decreases.

[0057] Considering these relationships, the amount of change in charging current and the contact force of cleaning member 417 have a correlation with the wear rate of photosensitive drum 413, so by obtaining the measurement results of current detection unit 416, it is possible to estimate the contact force of cleaning member 417.

[0058] The amount of change in current shown in FIG. 3 can be measured, for example, by a digital electrometer (product name: 5350, manufactured by ADC Corporation), and can be calculated, for example, by the following formulas (1) to (5).

[0059] Q=CV=ε0ε p SV / D p ···(1) Q is the surface charge of the photosensitive drum 413, C is the capacitance of the photosensitive drum 413, V is the surface potential of the photosensitive drum 413, ε0 is the dielectric constant of a vacuum, and ε p is the dielectric constant of the photosensitive drum 413, S is the area charged by the charging device 414, and D p indicates the film thickness of the photosensitive drum 413.

[0060] A(0)=ε0ε p LvV / D p0 ···(2) A(0) is the initial charging current, L is the charging width of the charging roller (charging device), v is the rotation speed of the photosensitive drum 413, and D p0 indicates the initial film thickness of the photosensitive drum 413. Note that the "initial" here refers to, for example, the start of measurement control during non-image formation.

[0061] D p (R)=D p0-αR···(3) R is the rotation speed of the photosensitive drum 413, D p (R) is the film thickness of the photosensitive drum 413 when it has rotated R times, and α is the wear rate of the photosensitive drum 413.

[0062] A(R)=ε0ε p LvV / (D p0 -αR)···(4) A(R) indicates the charging current when rotating R times.

[0063] ΔA=A(R)-A(0)=ε0ε p LvV(1 / (D p0 -αR)-1 / D p0 )···(5) ΔA indicates the amount of change in charging current.

[0064] In this way, the amount of change in the charging current can be obtained from the measurement results of the current detection unit 416.

[0065] However, there is a detection limit for the charging current based on the resolution of current detection unit 416. As described above, current detection unit 416 is configured to count up each time the charging current changes by a predetermined value while photosensitive drum 413 is rotating.

[0066] The detection limit of the charging current can be calculated, for example, by the following equation (6).

[0067] LimA=ε0ε p LvV(1 / (D p0 -αLimR)-1 / D p0 )···(6) LimA is the detection limit of the current detection unit 416, and LimR is the number of rotations of the photosensitive drum 413 when the charging current fluctuates by LimA.

[0068] In such a configuration, each time current detection unit 416 counts up, control unit 101 acquires the charging current measured by current detection unit 416 and the number of rotations of photosensitive drum 413 at the time of counting up, and associates these values ​​with each other and stores them in storage unit 72, etc. In other words, each time the charging current changes by a predetermined value, control unit 101 associates the charging current with the number of rotations of photosensitive drum 413 and stores them in storage unit 72.

[0069] When measuring the wear rate of photosensitive drum 413, control unit 101 can calculate wear rate α (=LimA / LimR) of photosensitive drum 413 using the charging current stored in memory unit 72 or the like and the number of rotations of photosensitive drum 413. Specifically, control unit 101 calculates the wear rate of photosensitive drum 413 using the amount of change in charging current after current detection unit 416 has counted up two or more times.

[0070] That is, control unit 101 calculates the wear rate of photosensitive drum 413 based on two or more combinations of charging currents and the rotation speed of photosensitive drum 413 stored in memory unit 72, and estimates the contact force of cleaning member 417. Control unit 101 corresponds to the "estimation unit" and "calculation unit" of the present invention.

[0071] 6, photoconductor drum 413 starts rotating when the charging current is not zero, but the charging current at this time is a value that does not reach the detection limit (LimA). In this case, current detection unit 416 performs the first count-up at a value that does not cause the amount of change in charging current to reach LimA. The number of rotations R1 of photoconductor drum 413 at this time is different from LimR.

[0072] Therefore, since there is a possibility that the accurate wear speed (contact force of the cleaning member 417) cannot be detected from the measurement value obtained only from the first count-up, the control unit 101 uses the amount of change in the charging current after the current detection unit 416 has counted up two or more times.

[0073] For example, the timing at which current detection unit 416 counts up next after R1 is when the number of rotations of photosensitive drum 413 is R2. In this way, the difference between R2 and R1 can be used as LimR, making it possible to obtain an accurate LimR.

[0074] Furthermore, from the viewpoint of improving reliability, it is preferable to use the amount of change in charging current after photosensitive drum 413 has been rotated for a certain long period of time (for example, counting up 10 times) to estimate the contact force.

[0075] In this way, the detected wear rate of photosensitive drum 413 can be stored in advance in a storage unit or the like, and by referring to the data shown in FIG. 4, etc., it is possible to estimate the contact force of cleaning member 417. That is, control unit 101 estimates the contact force of cleaning member 417 based on the measurement result of current detection unit 416.

[0076] Furthermore, control unit 101 detects, for example, the life of image forming unit 41 based on the estimated contact force of cleaning member 417. Control unit 101 determines the wear rate of photosensitive drum 413 from the estimated contact force of cleaning member 417 by referring to a table showing the relationship between the contact force of cleaning member 417 and the wear rate of photosensitive drum 413, as shown in FIG.

[0077] Then, control unit 101 detects the life of image forming unit 41 by dividing the estimated wear rate by the limit wear rate of photosensitive drum 413. For example, if the limit wear rate of photosensitive drum 413 is 15 μm and the wear rate of photosensitive drum 413 is 2 μm / 100k sheets, the life of image forming unit 41 is 750k sheets.

[0078] The wear rate of the cleaning member 417 may also be calculated from the estimated contact force of the cleaning member 417. In this case as well, the control unit 101 detects the life of the image forming unit 41 by dividing the estimated wear rate from the limit wear amount of the cleaning member 417. When the limit wear amount of the cleaning member 417 is 500 μm, 2 The wear rate of the cleaning member 417 is 100 μm 2If the print speed is 100k / 100k sheets, the life of the image forming unit 41 is 500k sheets.

[0079] In this way, by estimating the contact force of the cleaning member 417, the life of the image forming unit 41 can be detected.

[0080] Furthermore, the control unit 101 may adjust the contact force of the cleaning member 417 based on the estimated contact force of the cleaning member 417.

[0081] For example, in a configuration in which the cleaning member 417 is a fixed load, the contact force of the cleaning member 417 may gradually decrease over time or over the number of sheets used, as shown in Fig. 7A. In this case, the contact force may decrease and fall below a threshold value corresponding to a contact force that is likely to cause poor cleaning.

[0082] Therefore, control unit 101 adjusts the contact force so as to increase the contact force of cleaning member 417. For example, in a configuration in which member 417A (see FIG. 7B) that supports cleaning member 417 is movable by a motor (not shown), the contact force of cleaning member 417 is increased by moving cleaning member 417 toward photosensitive drum 413.

[0083] In this way, by estimating the contact force of the cleaning member 417, the contact force of the cleaning member 417 can be adjusted to suppress imperfect cleaning and the occurrence of image defects due to imperfect cleaning.

[0084] Furthermore, control unit 101 may change the amount of toner supplied during toner patch supply control based on the estimated contact force of cleaning member 417. Toner patch supply control is control for reducing torque and ensuring toner cleaning performance by supplying toner to photoconductor drum 413 outside of print jobs, between sheets during a print job, and in areas outside the image area during a print job. Control unit 101 corresponds to the "change unit" of the present invention.

[0085] 8, the amount of toner supplied in conventional toner patch supply control is constant regardless of the contact force of cleaning member 417. Therefore, if the contact force of cleaning member 417 is weak, supplying a toner patch during such toner patch supply control may result in poor cleaning.

[0086] Therefore, in this embodiment, when the estimated contact force of cleaning member 417 is weak, control unit 101 controls the amount of toner supplied to decrease accordingly. For example, in Fig. 8, the amount of toner supplied is controlled to decrease as the contact force becomes smaller than P, and when the contact force is P or more, the amount of toner supplied is kept constant.

[0087] In this way, by estimating the contact force of the cleaning member 417, it is possible to prevent imperfect cleaning and the occurrence of image defects caused by imperfect cleaning.

[0088] Furthermore, even if the charging current is measured multiple times by current detection unit 416, a situation may occur in which the amount of change in charging current per rotation remains unchanged for a predetermined number of rotations. This is expected to occur, for example, when light fatigue or an increase in residual potential of photosensitive drum 413 occurs. In such a situation, the increase in current due to wear of photosensitive drum 413 may be canceled out.

[0089] Therefore, if there is no change in the charging current after rotating the photosensitive drum 413 for a predetermined time (e.g., 3 minutes), the control unit 101 may interrupt the measurement of the charging current by the current detection unit 416 and interrupt the estimation control.

[0090] Furthermore, since the charged state of photosensitive drum 413 may not be stable for several minutes after photosensitive drum 413 starts to rotate, the amount of change in charging current during the first several minutes does not need to be used to estimate the contact force of cleaning member 417. In this case, the wear rate of cleaning member 417 may be detected using the measurement result of charging current after the first several minutes have elapsed.

[0091] According to the present embodiment configured as described above, the contact force of the cleaning member 417 can be estimated by providing a measuring device capable of measuring the charging current, and therefore the contact force of the cleaning member 417 can be detected without a complex configuration that requires a light source, a polarizer, an analyzer, an observation device, etc., as in Patent Documents 1 and 2. That is, in this embodiment, the contact force of the cleaning member can be detected with a simple configuration.

[0092] In the above embodiment, the number of rotations of photosensitive drum 413 is measured each time the charging current changes by a predetermined value, but the present invention is not limited to this. For example, the amount of change in charging current while photosensitive drum 413 rotates a predetermined number of times may be measured.

[0093] The predetermined number of rotations is, for example, the number of rotations required to measure the amount of change in charging current when the film thickness of photosensitive drum 413 is at its thickest. This predetermined number of rotations may be varied depending on the film thickness of photosensitive drum 413 when measuring the charging current.

[0094] In this way, the number of rotations of the photosensitive drum 413 can be reduced.

[0095] Furthermore, in the above embodiment, the wear rate of the photosensitive drum 413 is calculated, but the present invention is not limited to this, and the wear rate of the cleaning member 417 may be calculated.

[0096] In the above embodiment, the amount of change in charging current is used as a parameter related to the contact force of cleaning member 417, but the present invention is not limited to this. For example, the amount of change in temperature of photosensitive drum 413 may be used as the parameter.

[0097] It has been confirmed that the amount of temperature change in the vicinity of photosensitive drum 413 and the contact force of cleaning member 417 have a correlation such that the amount of temperature change increases as the contact force increases, as shown in FIG. 9A.

[0098] 9A is a diagram showing the measurement results of temperature detection unit 416A (see FIG. 9B) when temperature detection unit 416A is disposed inside photosensitive drum 413, and when photosensitive drum 413 is rotated while a fixed amount of toner (10 mg of toner per sheet of paper S) is supplied to photosensitive drum 413, and the contact force of cleaning member 417 is changed. The temperature change amount is the amount of change in temperature after photosensitive drum 413 has rotated a certain amount from the start of rotation.

[0099] The data shown in FIG. 9A is stored in advance in the memory unit 72 or the like, and when estimating the contact force, the detected temperature change amount is compared with the data, thereby making it possible to estimate the contact force of the cleaning member 417.

[0100] Furthermore, it is sufficient that temperature detection unit 416A is disposed near photosensitive drum 413. Furthermore, the amount of temperature change may be measured with the cooling fan or the like inside image forming apparatus 1 stopped.

[0101] Alternatively, a parameter may be the amount of distortion of cleaning member 417. The amount of distortion of cleaning member 417 is the amount by which cleaning member 417 is drawn in by the rotation of photosensitive drum 413.

[0102] It has been confirmed that the amount of distortion of cleaning member 417 and the contact force of cleaning member 417 have a correlation such that the amount of distortion of cleaning member 417 increases as the contact force increases, as shown in FIG. 10A.

[0103] 10A is a diagram showing the measurement results of strain gauge 416B (see FIG. 10B) when strain gauge 416B is placed on the surface of cleaning member 417 facing photosensitive drum 413, and photosensitive drum 413 is rotated while a fixed amount of toner (10 mg of toner per sheet of paper S) is supplied to photosensitive drum 413, thereby changing the contact force of cleaning member 417. The amount of strain is the amount of change in strain of cleaning member 417 compared to when cleaning member 417 is not in contact with photosensitive drum 413.

[0104] The data shown in FIG. 10A is stored in advance in the memory unit 72 or the like, and when estimating the contact force, the detected amount of distortion is compared with the data, thereby making it possible to estimate the contact force of the cleaning member 417.

[0105] 10A shows the amount of distortion of cleaning member 417 when toner of a fixed density is supplied. However, the contact force of cleaning member 417 may be estimated using the measurement results of the amount of distortion of cleaning member 417 when toner patches of multiple densities are supplied to photosensitive drum 413 as shown in FIG. 11 and the contact force of cleaning member 417 is set to 20 N / m and 10 N / m.

[0106] L1 is an approximation line of the measurement results of the amount of distortion when the contact force of the cleaning member 417 is 20 N / m, and L2 is an approximation line of the measurement results of the amount of distortion when the contact force of the cleaning member 417 is 10 N / m.

[0107] The intercept values ​​at L1 and L2 are the strain amounts at each contact force. In this way, by comparing the measurement results of strain gauge 416B when estimating the contact force of cleaning member 417 with the strain amount obtained from Figure 11, it is possible to estimate the contact force of cleaning member 417.

[0108] Furthermore, the distance between the cleaning member 417 and the photosensitive drum 413 may also be used as a parameter.

[0109] It has been confirmed that the distance between cleaning member 417 and photosensitive drum 413 and the contact force of cleaning member 417 have a correlation such that the distance decreases as the contact force increases, as shown in FIG. 12A.

[0110] 12A is a diagram showing the measurement results of distance sensor 416C (see FIG. 12B) when distance sensor 416C is placed on the surface of cleaning member 417 facing photosensitive drum 413, and when photosensitive drum 413 is rotated while a fixed amount of toner (10 mg of toner per sheet of paper S) is supplied to photosensitive drum 413, thereby changing the contact force of cleaning member 417. Distance sensor 416C is preferably, for example, a high-resolution capacitance type.

[0111] The data shown in FIG. 12A is stored in advance in the memory unit 72 or the like, and when estimating the contact force, the detected distance is compared with the data, thereby making it possible to estimate the contact force of the cleaning member 417.

[0112] Furthermore, as shown in FIG. 13A, in the case of a configuration having a biasing member 418 that biases cleaning member 417 against photosensitive drum 413, the length of biasing member 418 may be used as a parameter.

[0113] It has been confirmed that the length of the biasing member 418 that applies a load to the cleaning member 417 and the contact force of the cleaning member 417 are correlated such that the length increases as the contact force increases, as shown in FIG. 13B.

[0114] FIG. 13B is a diagram showing the length of urging member 418 based on the measurement results of imaging unit 416D (see FIG. 13A) when imaging unit 416D is placed at a location where it can image urging member 418, and photosensitive drum 413 is rotated while supplying a fixed amount of toner (10 mg of toner per sheet of paper S) to photosensitive drum 413, and the contact force of cleaning member 417 is changed.

[0115] The data shown in FIG. 13B is stored in advance in the memory unit 72 or the like, and when estimating the contact force, the contact force of the cleaning member 417 can be estimated by comparing the detected length of the urging member 418 with the data.

[0116] Furthermore, in each of the above embodiments, a measurement unit such as a current detection unit measures parameters related to the contact force, but the present invention is not limited to this, and may be configured to acquire and measure measurement results obtained by an external measurement device, for example. For example, if a high-precision device such as a current detection unit cannot be installed in the image forming apparatus 1, a service engineer or the like may connect a measurement unit to the image forming apparatus and measure parameters when estimating the contact force during maintenance or the like.

[0117] Furthermore, in the above embodiment, the control unit 101 is configured to include an estimation unit, a calculation unit, etc., but the present invention is not limited to this, and the estimation unit, calculation unit, etc. may be provided separately from the control unit 101.

[0118] Furthermore, in the above embodiment, the contact force of the cleaning member 417 is estimated, but the present invention is not limited to this, and may be configured to measure only a parameter related to the contact force of the cleaning member 417. However, in this configuration, for example, a user or an external device will determine the level of the contact force of the cleaning member based on only the parameter.

[0119] In the above embodiment, the charging device is a charging roller, but the present invention is not limited to this and may be a charging charger. However, if a charging charger is provided as the charging device in a configuration for measuring the amount of change in charging current, it is sufficient to simply install a roller member for measuring the charging current.

[0120] Furthermore, the above-described embodiments are merely examples of specific embodiments for carrying out the present invention, and the technical scope of the present invention should not be construed as being limited by these embodiments. In other words, the present invention can be carried out in various forms without departing from the gist or main features thereof. [Explanation of symbols]

[0121] 1. Image forming device 40 Image forming unit 101 Control section 413 Photosensitive drum 414 Charging device 415 Drum cleaning device 416 Current detection unit 417 Cleaning materials

Claims

1. An image forming apparatus including an image carrier that carries a toner image, and a cleaning member that comes into contact with and cleans the surface of the image carrier, a control unit that performs measurement control to measure a parameter related to a contact force of the cleaning member with the image carrier by rotating the image carrier while supplying toner to the image carrier during non-image formation; and a charging roller for charging the image carrier; Equipped with the parameter is a change in charging current between the image carrier and the charging roller; Image forming device.

2. a storage unit that stores the charging current and the number of rotations of the image carrier in association with each other every time the charging current changes by a predetermined value; a calculation unit that calculates a wear rate of the image carrier or the cleaning member, the wear rate having a correlation with the contact force, based on two or more combinations of the charging current and the rotation speed stored in the storage unit; and Equipped with The image forming apparatus according to claim 1 .

3. An image forming apparatus comprising an image carrier that carries a toner image, and a cleaning member that contacts and cleans the surface of the image carrier, a control unit that performs measurement control to measure a parameter related to a contact force of the cleaning member with the image carrier by rotating the image carrier while supplying toner to the image carrier during non-image formation; and a temperature detection unit that detects a change in temperature of the image carrier as the parameter; Equipped with Image forming device.

4. An image forming apparatus comprising an image carrier that carries a toner image, and a cleaning member that contacts and cleans the surface of the image carrier, a control unit that performs measurement control to measure a parameter related to a contact force of the cleaning member with the image carrier by rotating the image carrier while supplying toner to the image carrier during non-image formation; and a distance detection unit that measures a distance between the cleaning member and the image carrier as the parameter; Equipped with Image forming device.

5. the distance detection unit is disposed on a surface of the cleaning member facing the image carrier; The image forming apparatus according to claim 4 .

6. An image forming apparatus comprising an image carrier that carries a toner image, and a cleaning member that contacts and cleans the surface of the image carrier, a control unit that performs measurement control to measure a parameter related to a contact force of the cleaning member with the image carrier by rotating the image carrier while supplying toner to the image carrier during non-image formation; and a biasing member that biases the cleaning member against the image carrier; a length measuring unit for measuring the length of the biasing member; Equipped with Image forming device.

7. The length measuring unit is an imaging unit capable of imaging the urging member. The image forming apparatus according to claim 6 .

8. An estimation unit that estimates the contact force based on the parameters. The image forming apparatus according to any one of claims 1 to 7.

9. a life detection unit that detects the life of the image carrier or the cleaning member based on the parameter; The image forming apparatus according to any one of claims 1 to 8.

10. an adjustment unit that adjusts the contact force of the cleaning member based on the parameter; The image forming apparatus according to any one of claims 1 to 9.

11. a change unit that changes the amount of toner supplied in accordance with the parameter; The image forming apparatus according to any one of claims 1 to 10.

12. the changing unit supplies the toner to the image carrier at times other than when a print job is being performed, between sheets during the print job, and in an area outside an image area during the print job. The image forming apparatus according to claim 11.

Images