JP2016071302A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that can avoid the generation of abnormal noise from a fixing belt while extending the life of the fixing device as much as possible.SOLUTION: A fixing device includes: an endless fixing belt that has a heat source therein; a pressure roller that is arranged opposite to the fixing belt to form a nip part with the fixing belt; a storage part that stores the travel distance of the fixing belt and the number of recording media passed through the nip part; and linear velocity changing means for determining the linear velocity of the fixing belt other than during conveyance of the recording media from the relationship between the travel distance and the number of recording media passed through the nip part and changing the linear velocity of the fixing belt.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a fixing device and an image forming apparatus.

  In recent years, there has been a strong market demand for energy saving and high speed for image forming apparatuses such as printers, copiers, and facsimiles.

  In the image forming apparatus, a developer image is formed on the image carrier by an image forming process such as electrophotographic recording, electrostatic recording, and magnetic recording. This developer image is transferred to a recording medium such as a recording material sheet, printing paper, photosensitive paper, or electrostatic recording medium. The developer image transferred to the recording medium is heated and pressurized by a fixing device and fixed on the recording medium. As the fixing device, a contact heating type fixing device such as a heat roller method, a film heating method, and an electromagnetic induction heating method is widely adopted.

  As examples of such a fixing device, a belt-type fixing device (for example, Patent Document 1) and a surf fixing or film fixing device (for example, Patent Document 2) using a ceramic heater are known.

  Among these, the belt fixing device has the following problems.

  As problem 1, the warm-up time, that is, the time required for heating from a normal temperature state to a predetermined printable temperature, or the first print time, that is, the print operation is performed after receiving the print request, and the paper is discharged. It is desired to further shorten the time until completion.

  As problem 2, there is a problem of so-called temperature drop in which the amount of heat is insufficient at the beginning of continuous printing. This is because the required amount of heat has increased due to an increase in the number of sheets passed per unit time as the speed of the image forming apparatus increases.

  Problem 3 is poor fixing due to uneven heating of the belt. As a method for solving the above problem 1, surf fixing using a ceramic heater has been proposed. This system can be reduced in heat capacity and size as compared with the conventional belt-type fixing device. However, since only the nip portion is locally heated, the other portions are not heated, and the belt is in the coldest state at the entrance of the recording medium in the nip portion. Therefore, fixing failure is likely to occur. In particular, in a high-speed machine, the rotation of the belt is fast, and the amount of heat radiation outside the nip portion increases, so that fixing defects are more likely to occur.

  In order to solve the above problems 1 to 3, a fixing device including a driving roller that presses a recording medium, a fixing belt that rotates with the driving roller, and a heating device that heats the entire fixing belt is proposed. (For example, Patent Document 3).

  FIG. 1 is a schematic diagram of a fixing device 100 described in Patent Document 3. As shown in FIG. 1, the conventional fixing device 100 fixes a metal heat conductor 102 in the form of a pipe inside the fixing belt 101 so that the movement of the fixing belt 101 can be guided. The fixing belt 101 is heated via the metal heat conductor 102 by the internal heat source 103. Further, a pressure roller 106 that forms a nip portion N in contact with the metal heat conductor 102 via the fixing belt 101 is provided, and the fixing belt 101 is moved in the circumferential direction as the pressure roller 106 rotates. Let With this configuration, the entire fixing belt 101 constituting the fixing device 100 can be heated, the first print time from the heating standby time can be shortened, and the shortage of heat at the time of high-speed rotation can be solved. It has become.

  However, in order to further improve the energy saving and the first print time, it is necessary to further improve the thermal efficiency. Since the fixing belt 101 is indirectly heated through the metal heat conductor 102, the metal heat conductor 102 is changed. A configuration has been devised in which the fixing belt 101 is directly heated without intervention. In this configuration, it is possible to reduce the power consumption by greatly improving the heat transfer efficiency and to further shorten the first print time from the heating standby time. Further, the cost can be reduced due to the absence of the metal heat conductor 102.

  However, the following new problems occurred. That is, since the fixing belt is rotated with the driving roller, stick slip occurs at the sliding portion of the fixing belt, and abnormal noise is generated.

  In this regard, there is a method of increasing the rotation speed or linear speed of the fixing belt to avoid the generation of abnormal noise (for example, Patent Document 4).

  However, only by this method, the cumulative travel distance of the fixing device is extended, and the life of the fixing device is shortened.

  SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a fixing device that can avoid the occurrence of abnormal noise on the fixing belt while extending the life of the fixing device as much as possible.

  In order to solve the above problems, the present invention provides an endless fixing belt having a heat source therein, a pressure roller disposed opposite to the fixing belt and forming a nip portion with the fixing belt, and a traveling distance of the fixing belt And a storage unit for storing the number of sheets to be fed to the nip portion of the recording medium, and a linear velocity of the fixing belt by determining a linear velocity of the fixing belt other than when the recording medium is conveyed from the mutual relationship between the travel distance and the number of sheets to be passed. And a linear speed changing means for changing the speed.

  According to the present invention, it is possible to provide a fixing device that can avoid the occurrence of abnormal noise on the fixing belt while extending the life of the fixing device as much as possible.

It is a figure which shows the structural example of the fixing device of a prior art. 1 is a diagram illustrating a configuration example of an image forming apparatus. FIG. 2 is a cross-sectional view illustrating a configuration of a fixing device. 1 is a block diagram illustrating a configuration of an image forming apparatus. It is a figure which shows the example of a discriminant function. It is a figure which shows the example in case there exist multiple discriminant functions. It is a figure which shows the example of a linear velocity table. 3 is a flowchart illustrating an operation performed by a control unit of the image forming apparatus according to the first embodiment. 10 is a flowchart illustrating an operation performed by a control unit of the image forming apparatus according to the second embodiment. It is a figure which shows the example of the notification screen displayed on an input / output part.

  Hereinafter, a fixing device and an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
The image forming apparatus shown in FIG. 2 is a color printer using a tandem system in which image forming units for forming a plurality of color images are juxtaposed along the belt extending direction. However, the present invention is not limited to this system. It is also possible to target not only printers but also copiers and facsimile machines.

  In FIG. 2, the image forming apparatus 1 has a tandem structure in which photosensitive drums as image carriers capable of forming images as images corresponding to colors separated into yellow, cyan, magenta, and black are arranged in parallel. Is adopted.

  In the image forming apparatus 1 having the configuration shown in FIG. 2, the visible images formed on the photosensitive drums 4Y, 4C, 4M, and 4K face the photosensitive drums 4Y, 4C, 4M, and 4K in the direction of the arrow. A primary transfer process is performed on an intermediate transfer member (hereinafter referred to as a transfer belt) 30 using a movable fixing belt, and each image is superimposed and transferred.

  Thereafter, batch transfer is performed by executing a secondary transfer process on the recording medium P on which a recording sheet or the like is used.

  Around each of the photosensitive drums 4Y, 4C, 4M, and 4K, an apparatus for performing image forming processing according to the rotation of the photosensitive drum 5 is disposed. Now, the photosensitive drum 4K that performs black image formation is targeted. More specifically, a charging device, a developing device, a primary transfer roller 31, and a cleaning device that perform image forming processing along the rotation direction of the photosensitive drum 4K are arranged. For the writing performed after charging, the optical writing device 9 is used.

  The transfer to the transfer belt 30 is performed so that the visible image formed on each photoconductive drum is transferred to the same position on the transfer belt 30 while the transfer belt 30 moves in the direction of the arrow. The timing is shifted from the upstream side in the direction toward the downstream side by the voltage application by the primary transfer roller 31 disposed so as to be opposed to the respective photosensitive drums.

  The image forming apparatus 1 is disposed so as to face four image stations that perform image forming processing for each color and above each of the photosensitive drums 4Y, 4C, 4M, and 4K, and includes a transfer belt 30 and a primary transfer roller 31. A transfer belt unit 3 provided with a secondary transfer roller 36 as a transfer roller that is disposed opposite to the transfer belt 30 and is driven by the transfer belt 30 and rotates along with the transfer belt 30, a driven roller 34, and a transfer roller An intermediate transfer belt cleaning device 35 disposed opposite to the belt 30 for cleaning the transfer belt 30, and an optical writing device 9 serving as an optical writing device disposed below the four image stations. have.

  The optical writing device 9 is equipped with a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating polygonal mirror as a deflecting means, etc. Corresponding writing light is emitted to form an electrostatic latent image on the photosensitive drum.

  The image forming apparatus 1 is conveyed from the sheet feeding apparatus 10 as a sheet feeding cassette loaded with a recording medium P conveyed between the photosensitive drum 5 and the transfer belt 30, and the sheet feeding apparatus 10. The registration roller pair 12 that feeds the recording medium P that has been fed toward the transfer portion between the photosensitive drums and the transfer belt 30 at a predetermined timing in accordance with the toner image formation timing by the image station, and the recording medium P And a sensor (not shown) for detecting that the front end of the roller has reached the registration roller pair 12.

  The image forming apparatus 1 includes a fixing device 20 as a roller fixing type fixing unit for fixing the toner image to the recording medium P to which the toner image is transferred, and the fixed recording medium P outside the main body of the image forming apparatus 1. And a paper discharge roller 13 for discharging the paper. Further, the image forming apparatus 1 includes a paper discharge tray 14 that is disposed on the top of the main body of the image forming apparatus 1 and stacks the recording medium P that is discharged to the outside of the main body of the image forming apparatus 1 by a paper discharge roller 13. 14 and a developer supply unit 2 including toner bottles 2Y, 2C, 2M, and 2K filled with toners of colors of yellow, cyan, magenta, and black.

  In addition to the transfer belt 30 and the primary transfer roller 31, the transfer belt unit 3 includes a driving roller and a driven roller on which the transfer belt 30 is wound.

  The driven roller 34 also has a function as tension urging means for the transfer belt 30. For this reason, the driven roller 34 is provided with urging means using a spring or the like. The transfer belt unit 3, the primary transfer roller 31, the secondary transfer roller 36, and the cleaning device 35 constitute a transfer device.

  The sheet feeding apparatus 10 is disposed in the lower part of the main body of the image forming apparatus 1 and includes a feeding roller 11 as a sheet feeding roller that comes into contact with the upper surface of the uppermost recording medium P. The uppermost recording medium P is fed toward the registration roller pair 12 by being driven to rotate counterclockwise 11.

  Although not shown in detail, the cleaning device 35 provided in the transfer device includes a cleaning brush and a cleaning blade disposed so as to face and contact the transfer belt 30. The transfer belt 30 is cleaned by scraping and removing foreign matters such as residual toner by a cleaning brush and a cleaning blade.

  The cleaning device 35 also has a discharge means (not shown) for carrying out and discarding the residual toner removed from the transfer belt 30.

  FIG. 3 is a block diagram showing an embodiment of the fixing device 20 of the present invention. As shown in FIG. 3, the fixing device 20 includes an endless fixing belt 301 and a pressure roller 310 disposed to face the fixing belt 301.

  The pressure roller 310 includes a core material 311 formed of metal and an elastic member 312 that covers the core material 311.

  The fixing device 20 forms a nip portion N by a fixing belt 301 as a fixing member, a pressure roller 310 that is a pressure member facing the fixing belt 301, and a nip forming member 304. The nip forming member 304 is supported by a support member 305 that receives pressure from the pressure roller 310. Further, a sliding sheet (not shown) is installed in the nip forming member 304 shape. The above components excluding the pressure roller 310 are included in a pair of holding members.

  Inside the fixing belt 301 and the holding member, there is a halogen heater which is a heat source 302, and the region where the fixing member is directly heated by the light shielding member 306 is controlled by the light emission of the halogen heater. The light shielding member 306 exists outside the fixing belt 301 and blocks the fixing belt 301 of the temperature detection unit.

  When the pressure roller 310 rotates in the direction indicated by the arrow X1, the fixing belt 301 rotates along the direction indicated by the arrow X2. The recording medium P to which the developer image has been transferred is inserted in the direction indicated by the arrow X3 between the nip portion N formed by the fixing belt 301 and the pressure roller 310, and is heated and pressed, so that the developer image is recorded on the recording medium. Fixed to P.

  FIG. 4 is a block diagram illustrating a configuration of the image forming apparatus 1. As shown in FIG. 4, the image forming apparatus 1 includes a control unit 401, an image forming unit 402, a transport unit 403, a storage unit 404, an input / output unit 405, a sensor 20 </ b> S, and a fixing device 20. Prepare.

  The control unit 401 includes an arithmetic device such as a CPU (central processing unit).

  The image forming unit 402 forms an electrostatic latent image on the photosensitive drum 5 that is an electrostatic latent image carrier, and supplies a developer to the electrostatic latent image to form a developer image. The image forming unit 402 further transfers the developer image to the transfer belt 30 that is a developer image carrier, and transfers the transferred developer image onto the recording medium by the secondary transfer roller 36.

  The transport unit 403 transports the recording medium P one by one.

  The storage unit 404 includes a storage device such as a memory and a hard disk drive.

  The input / output unit 405 includes a display input device that inputs and outputs information such as a touch panel.

  The sensor 20 </ b> S detects a vibration having a frequency corresponding to the abnormal noise generated by the fixing belt 301. The control unit 401 determines whether the fixing belt 301 generates abnormal noise based on the output of the sensor 20S.

  The fixing device 20 includes a fixing device control unit 201, a driving unit 202, and a fixing device storage unit 203 in addition to the configuration described above in the description of FIG.

  The fixing device control unit 201 includes an arithmetic device such as a CPU. The fixing device control unit 201 can be omitted because the control unit 401 also serves as the operation thereof. Hereinafter, the operation of the fixing device control unit 201 will be described assuming that the control unit 401 also functions.

  The drive unit 202 rotates the pressure roller 310. The control unit 401 controls the drive unit 202 to rotate the pressure roller 310 at a predetermined speed. That is, the control unit 401 and the drive unit 202 function as a linear speed changing unit that changes the linear speed of the fixing belt 301.

  The fixing device storage unit 203 includes a storage device such as a nonvolatile memory. The fixing device storage unit 203 may be configured such that the storage unit 404 also has the function, and the fixing device 20 does not have the fixing device storage unit 203.

  The fixing device storage unit 203 stores a travel distance storage unit 203A, a sheet passing number storage unit 203B, a discrimination function storage unit 203C, a linear velocity storage unit 203D, and a linear velocity table 203E.

  The travel distance storage unit 203 </ b> A stores the cumulative travel distance of the fixing belt 301 calculated by the control unit 401 based on the output of the encoder provided in the pressure roller 310 or the drive unit 202 that drives the pressure roller 310.

  The sheet passing number storage unit 203 </ b> B stores the cumulative number of recording media P transported by the transport unit 403 to the fixing device 20 based on the output of a sheet passing sensor provided in the transport path of the recording medium P.

  The discriminant function storage unit 203 </ b> C stores a function indicating a boundary for changing the linear velocity, that is, the rotation speed of the fixing belt 301. The discriminant function is a function of the ratio of the current travel distance to the life of the travel distance of the fixing device 20 and the ratio of the current number of sheets to be passed to the life of the number of sheets to be passed through the fixing apparatus 20.

  The linear velocity storage unit 203D stores the current linear velocity of the fixing belt 301.

  The linear velocity table 203E stores the linear velocity of the fixing belt 301 for each region partitioned by the discriminant function.

  First, I will explain the abnormal noise at low speed, which is the subject of this time. In this fixing device 20, the fixing member (fixing belt 301) is driven by the driving force of the pressure roller 310 (the fixing member is not rotated by a gear or the like). Therefore, in the cross-sectional view in FIG. 3, the inner surface of the fixing belt 301 and the nip forming member are rubbed. Although not shown, the surface of the nip forming member 304 is covered with a sheet material having a low friction coefficient to reduce the friction coefficient with the inner surface of the fixing belt 301.

  Conventionally, it has been known that the sliding of the fixing belt 301 in the nip portion N causes stick-slip between the nip forming member 304 (including the sheet) and the fixing belt 301 to generate abnormal noise. From the conventional knowledge, it has been found that this stick slip is likely to occur when the linear velocity is low and the temperature becomes high. Therefore, the linear speed should be as fast as possible considering only the abnormal noise.

  However, the fixing device 20 performs a rotation operation other than when paper is passed. For example, the rotation operation is performed after the completion of printing for the purpose of preventing the temperature equalization or the local high temperature generated after the fixing device 20 completes continuous paper passing, the print preparation operation, the machine adjustment operation, and the like. There is also. If the linear speed of such operation increases, the travel distance (= total number of revolutions) of the fixing device 20 increases, and as a result, the life of the unit is shortened. Therefore, from the viewpoint of life, it is desirable that the linear velocity is slow within a range where stick-slip does not occur.

  FIG. 5 is a diagram illustrating an example of the discriminant function. The vertical axis represents the ratio (%) of the current travel distance to the life of the travel distance of the fixing device 20, and the horizontal axis represents the ratio (%) of the current number of sheets to be passed to the life of the sheet passing number of the fixing apparatus 20.

  The control unit 401 determines the linear velocity of the fixing belt 301 other than when the recording medium P is transported from the relationship between the travel distance and the number of sheets to be passed, and changes the linear velocity of the fixing belt 301.

  As shown in FIG. 5, when the discriminant function is the following equation (1), the discriminant function is divided into a region I above the discriminant function graph 501 and a region II below the discriminant function graph 501.

  Y = X (1)

  Region I indicates a range where the number of sheets to be passed is small compared to the travel distance. That is, the region I indicates that the fixing belt 301 rotates frequently except for the sheet passing, and the returning operation is large for the number of sheets passed.

  A large number of returning operations indicates that there is little continuous paper passing, and that the temperature of the fixing belt 301 at the nip portion N does not easily become high.

  If the fixing belt 301 does not easily reach a high temperature in the nip portion N, it is difficult to generate an abnormal noise due to stick-slip, which is a catch due to friction.

  Therefore, it is not necessary to increase the linear velocity in the region I state.

  Region II indicates a range in which the number of sheets passed is larger than the travel distance. That is, the area II indicates that the rotation operation of the fixing belt 301 other than the sheet passing is small and the returning operation is small for the number of sheets to be passed.

  A low return operation indicates that there is a lot of continuous paper passing, and that the temperature of the fixing belt 301 in the nip portion N tends to be high.

  If the fixing belt 301 is likely to become high temperature in the nip portion N, abnormal noise due to stick-slip, which is caught by friction, is likely to occur.

  Therefore, it is necessary to increase the linear velocity in the state of region II. Here, since the travel distance is originally relatively small in the region II, there is no problem even if the travel speed is accumulated earlier than the current state by increasing the linear speed.

  In addition, it has been empirically known that abnormal noise is less likely to occur when the fixing device 20 is new and is used for a certain level or more.

  Here, an area in which the ratio of the travel distance to the life travel distance and the ratio of the number of sheets to be passed to the life passage number is both a predetermined ratio or less and a predetermined ratio or more, for example, 3% or less and 50% or more is defined as an invariable area 502. When there is a state of the fixing device 20 in the invariable region 502, the life of the fixing device 20 can be controlled to be longer by not increasing the linear velocity even in the state of the region II.

  FIG. 6 is a diagram illustrating an example when there are a plurality of discriminant functions. The vertical axis represents the ratio (%) of the current travel distance to the life of the travel distance of the fixing device 20, and the horizontal axis represents the ratio (%) of the current number of sheets to be passed to the life of the sheet passing number of the fixing apparatus 20.

  As shown in FIG. 6, the discriminant function may be two or more. Further, the discriminant function may be a linear function or a quadratic or higher function.

  In FIG. 6, for example, the following equation (2) shown in the graph 601 and the following equation (3) shown in the graph 602 can be adopted as the discriminant function.

Y = 2X (2)
Y = 0.7X (3)

  In this case, abnormal noise is likely to occur in the order of region I, region II, and region III. Therefore, it is possible to control so as to increase the linear velocity in the order of region I, region II, and region III.

  Therefore, as the number of discriminant functions increases, finer control becomes possible, and generation of abnormal noise can be effectively avoided while keeping the life longer.

  Also in this example, when there is a state of the fixing device 20 in the invariable region 502, the life of the fixing device 20 is controlled to be longer by not increasing the linear speed even in the state of the region II or the region III. You can also.

  FIG. 7 is a diagram illustrating an example of the linear velocity table 203E. As shown in FIG. 7, the linear velocity table 203E can also store a plurality of patterns of linear velocities corresponding to regions partitioned by the discriminant function.

  For example, in the case of the initial setting, if abnormal noise is still generated even if the default 56 mm / sec is increased to 154 mm / sec in the area III, the line shown in the setting 1 by manual operation by a service person or automatically by the operation of the control unit 401 It is possible to change to a fast pattern.

  Two or more linear velocity patterns can be provided and stored in the linear velocity table 203E.

  Moreover, the linear velocity used in other existing modes can be used as the linear velocity stored in the linear velocity table 203E.

  For example, in the example of FIG. 7, 77 mm / sec is a linear velocity when printing is prepared, 154 mm / sec is a linear velocity when printing a medium-thick recording medium P, and 205 mm / sec is a plain paper when printing. The same linear velocity can be used for each linear velocity. In this case, the linear speed table of the motor itself can be simplified. Alternatively, as the linear velocity stored in the linear velocity table 203E, the linear velocity of the fixing belt 301 when the image forming apparatus 1 is started up can be used.

  When the fixing device 20 is replaced, the control unit 401 initializes the travel distance stored in the travel distance storage unit 203A and the sheet passing number stored in the sheet passing number storage unit 203B. Even if the selected linear velocity pattern in the linear velocity table 203E automatically returns to the initial setting when the fixing device 20 is replaced, it can be selected whether the selected linear velocity pattern is maintained or returned to the initial setting. It may be. The control unit 401 determines whether to maintain the linear velocity pattern selected based on the input from the input / output unit 405 or return to the initial setting.

  If the image forming apparatus 1 is configured so as to maintain the selection of the linear velocity pattern, it is possible to form an image with a more suitable linear velocity pattern unless the user's usage pattern is significantly changed.

  Further, when the three linear velocity regions for the rotation operation after the sheet passing are set as described above, the fixing belt 301 rotates at linear velocity corresponding to each of the regions I to III as shown in FIG. . If there is a user who uses such an abnormal sound in the initial setting, the linear speed can be changed from the initial setting to setting 1 and selected by the serviceman. Thereby, even if abnormal noise occurs, the abnormal linear noise is prevented by increasing the entire linear speed table by manual operation.

  The fixing device 20 can be configured to select and set whether or not to increase the linear speed when the control unit 401 determines that the condition for changing the linear speed is satisfied. This setting is stored in the storage unit 404 or the fixing device storage unit 203, and the control unit 401 reads this setting and determines whether to increase the linear velocity.

  When the travel distance is ahead, the unit is deteriorated for the number of sheets to be passed. If the linear velocity is further increased in this state, the fixing belt 301 is further deteriorated. It can be determined in advance whether to change the linear speed table giving priority to the suppression of abnormal noise, or not to change the linear speed table giving priority to the unit life.

  FIG. 8 is a flowchart illustrating an example of an operation performed by the control unit 401 of the fixing device 20. As shown in FIG. 8, when the image forming apparatus 1 forms an image, the control unit 401 reads the linear velocity from the linear velocity storage unit 203D, and rotates the fixing belt 301 generated after the image formation, that is, when the recording medium is conveyed. Rotating operations other than are performed at the read linear velocity.

  The linear velocity of the fixing belt 301 is maintained at a predetermined linear velocity by controlling the rotation of the pressure roller 310.

  In step 801, the control unit 401 adds the number of sheets having undergone image formation to the cumulative number of sheets to be passed and stores it in the sheet passing number storage unit 203B.

  In step 802, the control unit 401 adds the distance traveled by the fixing belt 301 during the image formation to the cumulative travel distance and stores it in the travel distance storage unit 203A.

  In step 803, the control unit 401 calculates a ratio of the current sheet passing number to the life of the sheet passing number of the fixing device 20 and a ratio of the current travel distance to the life of the fixing device 20 line distance, and the invariable area. It is determined whether 502 exists.

  If the control unit 401 determines that it is not in the immutable region 502, the control unit 401 proceeds to step 804, and if it is determined that it is in the immutable region 502, the control unit 401 proceeds to step 808.

  In step 804, the control unit 401 reads the discriminant function from the discriminant function storage unit 203C, and determines the area to which the current state belongs from the calculated ratio of travel distance and the ratio of the number of sheets to be passed.

  In step 805, the control unit 401 reads the linear velocity table 203E.

  In step 806, the control unit 401 determines whether the linear velocity corresponding to the region to which the current region belongs, read from the linear velocity table 203E, matches the current linear velocity read from the linear velocity storage unit 203D.

  If the control unit 401 determines that the linear velocity corresponding to the region to which the current region belongs and the current linear velocity read from the linear velocity storage unit 203D match, the control unit 401 determines that the linear velocity change is unnecessary and performs processing. Exit.

  When determining that the linear velocity corresponding to the region to which the current region belongs does not match the current linear velocity read from the linear velocity storage unit 203D, the control unit 401 determines that the linear velocity needs to be changed. Proceed to step 807.

  In step 807, the control unit 401 stores the linear velocity corresponding to the region to which the current region belongs in the linear velocity storage unit 203D.

  In step 808, the control unit 401 returns the linear velocity to the initial setting value, and ends the process. Here, the initial setting value means an initial setting value stored in the linear velocity table 203E when the storage unit 404 or the fixing device storage unit 203 stores the linear velocity table 203E. If the linear velocity table 203E is not stored, it means a default linear velocity.

  As described above, the image forming apparatus 1 of the present embodiment stores the travel distance and the number of sheets to be passed of the fixing device 20, and the control unit 401 conveys the recording medium P based on the travel distance and the number of sheets to be passed. In other cases, the linear velocity of the fixing belt 301 is determined.

  In particular, the image forming apparatus 1 according to the present embodiment stores the travel distance of the fixing device 20 and the number of sheets to be passed, and the control unit 401 uses the travel distance and the number of sheets to be passed to make the travel distance correspond to the number of sheets to be passed. If it is less, change the line speed to be faster.

  Therefore, there is an effect that it is possible to avoid the occurrence of noise on the fixing belt while extending the life of the fixing device as much as possible.

(Second Embodiment)
The configurations of the fixing device 20 and the image forming apparatus 1 of the present embodiment are the same as the configurations of the fixing device 20 and the image forming apparatus 1 of the first embodiment.

  Although not particularly illustrated, the image forming apparatus 1 is configured to include a sensor 20S that detects vibrations or sounds.

  The position where the sensor 20S is provided is not a problem even in the fixing device 20, but considering that the replacement cycle of the fixing device 20 is faster than that of the main body, the sensor 20S is also replaced at the time of replacement. .

  When a vibration or sound wave of a specific frequency component of abnormal noise is detected in advance, the linear velocity table 203E in FIG. 7 is raised by one step, that is, a linear velocity faster than the linear velocity currently selected from the linear velocity table 203E is increased. Select (initial setting → setting 1 or setting 1 → setting 2). As a result, the occurrence of abnormal noise is detected and the linear speed table 203E is automatically changed to prevent the abnormal noise from recurring.

  When abnormal noise occurs, the user himself / herself can inform the image forming apparatus 1 that the abnormal noise has occurred and change the linear velocity table.

  Specifically, a mechanical button is provided on the operation panel which is the input / output unit 405 of the image forming apparatus 1, or a button such as “Please press here when abnormal noise occurs” is provided on the liquid crystal screen. Can be considered. With this configuration, the manufacturing cost can be reduced.

  It is ideal to select whether or not to use this mode, and it is desirable not to display the button from the operation panel when it is determined that the mode is not used. This is because if the user accidentally presses, the linear speed of rotation is increased after printing is completed, and the service life is shortened.

  In the case where the travel distance is ahead (region I where Y> X in FIG. 5), the result is that the travel distance is further advanced if the line speed selected by the line speed table 203E is changed to increase the line speed. This leads to an early life of the unit. In this case, it is desirable to determine in advance whether or not to change the linear velocity table in the internal mode or the like. Determine whether the service person should change the line speed based on the usage status of the customer's machine, etc., or not to change the line speed table (prior to the unit life).

  For example, it is assumed that the fixing device 20 is currently in the region II. Further, it is assumed that the initial setting of FIG. 7 is applied to the linear velocity table 203E. It is assumed that the rotation starts after the printing is finished and the region I is entered after 5 seconds. In the case of the control in which the rotation is completed for 10 seconds after the end of printing, just entering the region I after 5 seconds does not change to 77 mm / sec for 0 to 5 seconds and 56 mm / sec for 5 to 10 seconds. Do not change during a series of operations. Therefore, in this case, it is 77 mm / sec for 0 to 10 seconds. The rotation after the next time is set to 56 mm / sec because the region I is reached.

  Many image forming apparatuses 1 have means for recording the number of sheets and the travel distance of the fixing device 20 that is currently installed. When a new fixing device 20 is installed, the image forming apparatus 1 is installed in the image forming apparatus 1. A new state of the fixing device 20 is detected and data such as the number of sheets to be passed and the travel distance are cleared. Further, the cleared value is rewritten to the previous counter item of the fixing device 20. At this time, it is possible to select whether the linear velocity table 203E is also returned to the initial setting, or whether the current linear velocity table 203E is left as it is.

  For example, it is assumed that abnormal noise is likely to occur due to some trouble in the fixing device 20, and the linear velocity table 203E is in the state of setting 2 in FIG. In this case, since an abnormal noise has occurred due to the fixing device 20, it is considered that the abnormal noise will not be generated by replacing the fixing device 20, and it is desirable that the linear velocity table 203E be returned to the initial setting.

  In addition, it is in a situation where abnormal noise is likely to occur due to the customer's usage, such as a large number of continuous paper passes, not a malfunction of the fixing device 20, and if it is set to 2 after the fixing device 20 is replaced However, it is desirable to continue setting 2. (When returning to the initial settings, another noise will be generated). In this way, it is desirable to be able to select whether to clear the setting.

  FIG. 9 is a flowchart illustrating an operation performed by the control unit 401 of the image forming apparatus 1 of the present embodiment.

  As shown in FIG. 9, when the image forming apparatus 1 forms an image, the control unit 401 reads the linear velocity from the linear velocity storage unit 203D and rotates the fixing belt 301 generated after the image formation, that is, when the recording medium is conveyed. Rotating operations other than are performed at the read linear velocity.

  The linear velocity of the fixing belt 301 is maintained at a predetermined linear velocity by controlling the rotation of the pressure roller 310. That is, even if the control unit 401 detects that abnormal noise is generated based on the output of the sensor 20S, the linear speed is not changed during the series of operations, and one sheet of fixing operation is completed. Change from.

  In step 901, the control unit 401 adds the number of sheets having undergone image formation to the cumulative number of sheets to be passed and stores it in the sheet passing number storage unit 203B.

  In step 902, the control unit 401 adds the distance traveled by the fixing belt 301 during the image formation to the cumulative travel distance and stores it in the travel distance storage unit 203A.

  In step 903, the control unit 401 determines whether an abnormal sound is generated based on the output of the sensor 20S. The control unit 401 determines that an abnormal sound is generated when a frequency component peculiar to the abnormal sound stored in the storage unit 203 is detected by the sensor 20S.

  The control unit 401 proceeds to step 904 when it is determined that an abnormal sound is generated based on the output of the sensor 20S, and ends the process when it is determined that no abnormal sound is generated.

  In step 904, the control unit 401 determines whether or not the automatic change mode is a mode for changing the linear velocity without waiting for a user instruction. If the control unit 401 determines that the automatic change mode is selected, the process proceeds to step 905. If the control unit 401 determines that the automatic change mode is not selected, the control unit 401 proceeds to step 908.

  In step 905, the control unit 401 calculates a ratio of the current sheet passing number to the lifetime of the sheet passing number of the fixing device 20 and a ratio of the current traveling distance to the lifetime of the traveling distance of the fixing device 20. The control unit 401 reads the discriminant function from the discriminant function storage unit 203C, and determines the region to which the current state belongs from the calculated ratio of travel distance and the ratio of the number of sheets passed.

  In step 906, the control unit 401 reads the linear velocity table 203E.

  In step 907, the control unit 401 changes the line speed by writing the line speed corresponding to the area to which the current state read from the line speed table 203E belongs to the line speed storage unit 203D.

  In step 908, the control unit 401 determines whether or not the notification mode is a mode for notifying the user that an abnormal sound is being generated. If the control unit 401 determines that the notification mode is selected, the process proceeds to step 909. If the control unit 401 determines that the notification mode is not selected, the control unit 401 ends the process.

  In step 909, the control unit 401 outputs a notification that abnormal noise has occurred to the input / output unit 405. In addition, the control unit 401 outputs to the input / output unit 405 an instruction button that prompts an input of a linear velocity change instruction.

  In step 910, the control unit 401 determines whether or not a linear velocity change instruction has been issued from the input / output unit 405. The control unit 401 proceeds to step 905 when it is determined that there is an instruction to change the linear velocity from the input / output unit 405, and ends the process when it is determined that there is no instruction.

  FIG. 10 is a diagram illustrating an example of a notification screen 1001 displayed on the input / output unit 405. As shown in FIG. 10, in the notification mode, the control unit 401 causes the input / output unit 405 to display a notification screen 1001 when the sensor 20S detects the occurrence of an abnormal sound based on the output.

  The notification screen 1001 includes a notification column 1002 that displays a notification output that is a notification message indicating that abnormal noise has occurred, such as “An abnormal noise has occurred in the fixing device. Do you want to adjust?”.

  Further, the control unit 401 instructs the notification column 1002 to change from the notification mode to the non-notification mode, the “YES” instruction button 1002A for instructing the change of the linear velocity, the “NO” skip button 1002B to instruct the skip. And a transition button 1002C of “Do not notify in the future” is displayed.

  As described above, the image forming apparatus 1 of the present embodiment includes the sensor 20S that detects the occurrence of abnormal noise, stores the travel distance of the fixing device 20 and the number of sheets to be passed, and the control unit 401 controls the sensor 20S. When the occurrence of abnormal noise is detected based on the output, the linear speed of the fixing belt 301 in cases other than the conveyance of the recording medium P is determined and changed based on the travel distance and the number of sheets to be passed.

  Therefore, there is an effect that it is possible to avoid occurrence of abnormal noise of the fixing belt 301 while extending the life of the fixing device as much as possible without imposing a burden on the user.

1: Image forming devices 4Y, 4M, 4C, 4K: Photoconductor drum 20: Fixing device 20S: Sensor 30: Transfer belt 31: Primary transfer roller 36: Secondary transfer roller 203: Fixing device storage unit 203E: Linear speed table 301: fixing belt 302: heat source 310: pressure roller 402: image forming unit 405: input / output unit

JP 2004-286922 A Japanese Patent No. 2861280 JP 2007-334205 A JP 2008-40420 A

Claims (10)

An endless fixing belt having a heat source therein;
A pressure roller disposed opposite to the fixing belt and forming a nip portion with the fixing belt;
A storage unit for storing the travel distance of the fixing belt and the number of sheets that pass through the nip portion of the recording medium;
Linear speed changing means for determining the linear speed of the fixing belt other than when the recording medium is transported from the mutual relationship between the travel distance and the number of sheets to be passed and changing the linear speed of the fixing belt;
A fixing device. The linear velocity changing means is
The fixing device according to claim 1, wherein the linear velocity is changed only when the travel distance and the number of sheets to be passed are within a predetermined range. The linear velocity changing means is
The fixing device according to claim 1, wherein the linear velocity after image formation is used by diverting the linear velocity used in another existing operation. The storage unit
Further storing a linear velocity table for storing the linear velocity;
A sensor for detecting abnormal noise generated by the fixing device;
The linear velocity changing means is
The said linear velocity faster than the said linear velocity currently selected from the said linear velocity table is selected when abnormal sound is detected based on the output of the said sensor. Fixing device. The linear velocity changing means is
The fixing device according to any one of claims 1 to 4, wherein the linear velocity is not changed during a series of operations.   An image forming apparatus including the fixing device according to claim 1. An input / output unit for inputting / outputting information is further provided.
The linear velocity changing means, when detecting abnormal noise based on the output of a sensor that detects abnormal noise generated by the fixing device, outputs a notification to the input / output unit that abnormal noise has been detected. The image forming apparatus according to claim 6, wherein the linear velocity selected from a linear velocity table that stores the linear velocity is changed based on an input from an entry output unit. A sensor for detecting abnormal noise generated by the fixing device;
The linear velocity changing means is
The image forming apparatus according to claim 7, further comprising: a notification mode in which the notification output is performed; and a non-notification mode in which the notification output is not performed even when an abnormal sound is detected based on the output of the sensor. . The linear velocity changing means is
9. The image forming apparatus according to claim 6, wherein whether or not the linear velocity is increased can be set when a condition for changing the linear velocity is satisfied.   When the fixing device is replaced, the travel distance and the number of sheets to be stored that are stored in the storage unit are initialized, and the linear speed table that stores the linear speed is initialized according to the setting, or the current setting of the fixing device The image forming apparatus according to claim 6, further comprising a control unit that determines whether to maintain the linear velocity.

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