JP2007050940A - Sheet conveying device, and image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet conveying device capable of determining the degree of degradation of the conveying performance of a conveying roller with excellent accuracy. <P>SOLUTION: The sheet conveying device 20 comprises conveying rollers 23<SB>i</SB>(i=1 to N) for conveying sheets, and a control unit 26 which measures conveying speed data for indicating the sheet conveying speed by the conveying rollers 23<SB>i</SB>and determines the degree of degradation of the conveying performance of the conveying rollers 23<SB>i</SB>by using a plurality of sets of the measured conveying speed data. The control unit 26 neglects the measured conveying speed data when detecting a predetermined phenomenon in which the conveying speed data to be measured are possibly data not adequate for the determination. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet such as paper using a conveying roller, and an image forming apparatus including the same.

  An image forming apparatus such as a printer or a copying machine incorporates a sheet conveying apparatus that conveys a sheet such as a sheet along a predetermined conveying path. In this type of sheet conveying apparatus, a predetermined number of conveying rollers are arranged on the conveying path, and the sheet is conveyed by rotationally driving the conveying rollers. In general, a driving roller and a driven roller constitute a conveying roller, and the sheet is sandwiched between the pair of rollers, the driving roller is rotated by a motor or the like, and the sheet is conveyed by friction between the roller and the sheet. .

  In the sheet conveying apparatus, every time a sheet is conveyed, the surface of the conveying roller is worn, and the conveying performance of the conveying roller is deteriorated. Specifically, when the friction coefficient on the surface of the conveying roller is reduced, slip occurs between the roller and the sheet, and the sheet conveying speed is reduced.

  In the image forming apparatus, if the conveyance roller is worn and the sheet cannot be conveyed within a predetermined jam detection time to a predetermined point on the downstream side of the conveyance roller, it is determined as a jam and the image forming operation is stopped. . For this reason, it is necessary to replace a transport roller that has reached the end of its life due to wear. In general, the transport roller is one of consumables that are frequently replaced in the market, and its life is determined by the number of printed sheets. However, there are many cases where the transport roller is erroneously replaced before the end of its life. For example, when troubles such as frequent jams occur, when the cause cannot be specified, the conveying roller is often replaced for the time being. In this case, there is a case where a plurality of transport rollers are replaced at once.

  Under such circumstances, it is important to accurately determine the life of the conveying roller in the sheet conveying apparatus, and several techniques for that purpose have been proposed. For example, in Patent Document 1, the sheet conveyance time between two points on the downstream side of the roller is measured, and the ratio of the sheet conveyance time exceeding a set value among a certain number of sheets is obtained. The technique for judging is shown.

JP-A-8-85671

  However, since all the measurement data is used in the technique described in Patent Document 1, even when an event occurs in which there is a high possibility that the measurement data becomes data inappropriate for life determination (ie, noise). The measurement data obtained at that time is used for the life determination, and the determination cannot be made with high accuracy. For example, if a piece of paper remains on the conveyance path after jamming, or if the cover is not properly closed and the contact pressure between the driving roller and the driven roller is low, a sudden type that does not depend on deterioration of the conveyance roller A jam occurs, but the measured data at this time is also used for determining the life.

  Therefore, the present invention provides a sheet conveying apparatus and an image forming apparatus that can accurately determine the degree of deterioration of the conveying performance of the conveying roller.

  A sheet conveying apparatus according to the present invention includes a conveying roller that conveys a sheet, a conveying speed measuring unit that measures conveying speed data indicating a conveying speed of the sheet by the conveying roller, and a plurality of units measured by the conveying speed measuring unit. A deterioration degree determination unit that determines a degree of deterioration of the conveyance performance of the conveyance roller using the conveyance speed data, and the deterioration degree determination unit is measured by the conveyance speed measurement unit. When a predetermined event with a high possibility that the conveyance speed data is inappropriate for the determination is detected, the conveyance speed data measured by the conveyance speed measurement unit at that time is ignored.

  In a preferred aspect of the present invention, when the jam occurs, the deterioration degree determination unit determines whether or not the jam is a sudden jam that is not caused by the deterioration of the transport roller, and is a sudden jam. If it is determined, the conveyance speed data measured when the jam occurs is ignored. In this configuration, when the jam occurs, it is preferable that the deterioration degree determination unit determines whether or not the jam is a sudden jam based on the immediately preceding conveyance speed data.

  According to a preferred aspect of the present invention, the conveyance speed measuring means has a predetermined distance from the upstream end of the preceding sheet conveyance path provided on the upstream side of the conveyance roller as the conveyance speed data to the downstream side from the conveyance roller. The sheet conveyance time to a point far away from the sheet is measured, and the deterioration degree determination unit ignores the conveyance speed data measured for the sheet when detecting a delay of a predetermined period or more of sheet conveyance in the preceding sheet conveyance path. To do.

  Also, in a preferred aspect of the present invention, the deterioration degree determination means distinguishes and uses the conveyance speed data for each sheet type, and determines the deterioration degree for each sheet type. In a preferred aspect of the configuration, the deterioration level determination includes: a sheet type setting unit that receives a setting of a type of a sheet to be conveyed; and a sheet type detection unit that detects a type of a sheet that is actually conveyed. When detecting a mismatch between the type set by the sheet type setting unit and the type detected by the sheet type detection unit, the unit ignores the conveyance speed data measured for the sheet in which the mismatch is detected.

  Further, the sheet conveying apparatus according to the present invention is measured by a conveying roller that conveys the sheet, a conveying speed measuring unit that measures conveying speed data indicating a conveying speed of the sheet by the conveying roller, and the conveying speed measuring unit. A deterioration degree determination unit that determines a degree of deterioration of the conveyance performance of the conveyance roller by using a plurality of conveyance speed data. It is characterized in that it is used separately for each type, and the degree of deterioration is determined for each type of sheet.

  An image forming apparatus according to the present invention includes any one of the above-described sheet conveying devices.

  According to the present invention, it is possible to provide a sheet conveying apparatus and an image forming apparatus that can accurately determine the degree of deterioration of the conveying performance of the conveying roller.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic configuration diagram of an image forming apparatus 100 including a sheet conveying device 20 according to the present embodiment. The image forming apparatus 100 is an apparatus that prints an image on a sheet S (hereinafter simply referred to as “sheet”) such as paper, such as a copying machine, a printer, and a facsimile machine. Here, the electrophotographic apparatus performs printing by an electrophotographic method. It is. However, the image forming apparatus 100 may use another printing method such as an inkjet method. In FIG. 1, the image forming apparatus 100 includes an image forming unit 10 and a sheet conveying device 20.

  The image forming unit 10 forms an image on a sheet according to an electrophotographic process. Since the image forming unit 10 is widely known, illustration and detailed description of its specific configuration are omitted. In brief, the image forming unit 10 typically includes a photoconductor, a charging device disposed around the photoconductor, an exposure device, a developing device, a transfer device, a cleaning device, and a fixing device. Then, an electrostatic latent image is formed on the photosensitive member by the charging device and the exposure device, the electrostatic latent image is visualized (toner image) by the developing device, and the toner image on the photosensitive member is transferred onto the sheet by the transfer device. The transferred toner image is fixed on the sheet by a fixing device.

  The sheet conveying device 20 conveys the sheet S along a conveying path using a conveying roller. In the present embodiment, the sheet conveying apparatus 20 is placed on a sheet stored in the sheet feeding tray 1 or a manual feed tray (not shown). The transferred sheet is conveyed to a transfer portion, the transferred sheet is conveyed to a fixing device, and the fixed sheet is discharged to a discharge tray 2. In FIG. 1, only one sheet feed tray 1 is shown, but actually, a plurality of sheet feed trays 1 are provided, and each sheet feed tray 1 is distinguished for each sheet type. A seat is accommodated. Here, in the present specification, the type of sheet is specifically a type based on the size, material, or thickness of the sheet, or a combination thereof.

The sheet conveying apparatus 20 includes a conveying path 21 in which guides for guiding sheets are appropriately arranged. The conveyance direction upstream end P _S of the conveyance path 21, a feed roller 22 for feeding one by one the sheets stored in the sheet feed tray 1 to the conveying path 21 is provided. On the downstream side in the transport direction of the feed roller 22, the transport roller 21 along the transport path 21 from the upstream side in the transport direction (hereinafter simply referred to as “upstream side”) to the downstream side in the transport direction (hereinafter simply referred to as “downstream side”) A predetermined number N of conveying rollers 23 ₁ , 23 ₂ ,..., 23 _N−1 , 23 _N (hereinafter collectively referred to as “conveying rollers 23” as appropriate) are provided. Here, for example, ten transport rollers 23 (that is, N = 10) are provided, but at least one transport roller 23 may be provided.

Each transport roller 23 is composed of a roller pair of a drive roller 23a that is rotationally driven by a motor or the like, and a driven roller 23b that is driven to rotate as the roller 23a rotates. The driving roller 23 a and the driven roller 23 b are each formed by forming a rubber roll around a metal rotation shaft, and the rotation shaft is disposed along the width direction of the transport path 21. The driving roller 23a and the driven roller 23b are pressed against each other with the conveyance path 21 therebetween, and the sheet is nipped and conveyed by a nip portion formed thereby. The downstream end in the conveyance direction P _E of the conveying path 21, the discharge roller 24 is arranged comprising a pair of rollers.

  In addition to the rollers 22, 23, and 24, other conveyance means such as a conveyance belt may be installed in the conveyance path 21.

Sensors 25 ₁ that detect the presence or the passage of a sheet at each sheet conveyance point at predetermined sheet conveyance points P ₁ , P ₂ ,... P _N−1 , P _N , P _{N + 1} on the conveyance path 21. , 25 ₂ ,..., 25 _N−1 , 25 _N , 25 _{N + 1} (hereinafter collectively referred to as “sensor 25” as appropriate). In the present embodiment, as shown in FIG. 1, each sensor 25 _i (i = 1 to N) is disposed close to the downstream side of each transport roller 23 _i , and sensor 25 _{N + 1} is transported. It is located at a point a predetermined distance downstream from roller 23 _N.

  Furthermore, the sheet conveying apparatus 20 includes a control unit 26 that controls the apparatus. Here, the control unit 26 is a circuit board on which a CPU (Central Processing Unit), a ROM (Read Only Member), a RAM (Random Access Memory), and the like are mounted, and the function is stored in a recording medium such as a ROM. This is realized by the executed program being executed by the CPU. In the present embodiment, the control unit 26 controls not only the sheet conveying apparatus 20 but the entire image forming apparatus 100.

  FIG. 2 is a block diagram illustrating a functional configuration of the control unit 26. In FIG. 2, the control unit 26 includes a roller drive control unit 26a, a sheet type setting unit 26b, a sheet type detection unit 26c, a jam detection unit 26d, a conveyance speed measurement unit 26e, a deterioration degree determination unit 26f, and a notification unit 26g. .

  The roller drive control unit 26 a controls the drive of the feed roller 22, the transport roller 23, and the discharge roller 24 by controlling the rotational drive of one or more motors. Specifically, the roller drive control unit 26 a controls the drive start timing, the drive end timing, and the rotation speed for each of the rollers 22, 23, and 24 in accordance with the timing of image formation by the image forming unit 10. For example, when 10 sheets are continuously printed, the roller drive control unit 26a controls the driving of the rollers 22, 23, and 24 so that 10 sheets flow through the conveyance path 21 at predetermined intervals. At this time, paying attention to one sheet, the sheet stored in the paper feed tray 1 is sent out to the transport path 21 by the feed roller 22 and sequentially transported downstream by the transport roller 23, and the discharge roller 24 is discharged to the discharge tray 2. In the present embodiment, the control unit 26 has a plurality of target transport speeds (52, 104, 165, 208 mm / s), and is based on predetermined conditions such as black and white printing / color printing, sheet type, and user settings. To determine the target transport speed. The roller drive control unit 26a performs drive control of the rollers 22, 23, and 24 so that the sheet is conveyed at a determined target conveyance speed.

  The sheet type setting unit 26b receives the setting of the type (size, material, thickness, etc.) of the sheet to be conveyed on the conveyance path 21 from the user via a user interface such as an operation panel (not shown).

  The sheet type detection unit 26c is configured to detect a sheet actually conveyed on the conveyance path 21 based on outputs from a size detection sensor, a material detection sensor, a thickness detection sensor, and the like (not illustrated) installed in the conveyance path 21. Detect type (size, material, thickness, etc.).

The jam detection unit 26d detects a jam (paper jam) in the conveyance path 21 based on an output of an appropriate sensor (sensor 25 in the present embodiment). Specifically, the jam detection unit 26d detects a jam when the arrival of the leading edge of the sheet is not detected by the predetermined sensor 25 within a predetermined jam detection time from a predetermined reference timing. For example, in the first jam detection method, after the sensor 25 _i (i = 1 to N) detects the arrival of the sheet, the sensor 25 _{i + 1} does not detect the arrival of the sheet within the jam detection time. It is determined that a jam has occurred. In the second jam detection method, for each sheet to be conveyed, after the motor for driving the feed roller 22 is turned on, the sensor 25 _i (i = 1 to N + 1) is detected within a preset jam detection time. If 25 _i does not detect the arrival of the sheet, it is determined that a jam has occurred.

The conveyance speed measurement unit 26 e measures, for each conveyance roller 23, conveyance speed data indicating the sheet conveyance speed by the conveyance roller 23. In the present embodiment, the conveyance speed measurement unit 26e uses the sensor 25 _{i + 1} as the conveyance speed data for the conveyance rollers 23 _i (i = 1 to N) after the sensor 25 _i detects the arrival of the sheet. The time until the arrival of the sheet is detected (sheet conveyance time) is measured. In a preferred embodiment, the conveyance speed measuring unit 26e sets each sensor 25 _k (k = 1 to N + 1) from the reference time to the on time of the motor that drives the feed roller 22 as the reference time for each conveyed sheet. Then, the time t _k until the sheet is detected is measured, and the sheet conveyance time (t _{i + 1} −t _i ) is calculated as the conveyance speed data for each conveyance roller 23 _i . In the following description, “conveying speed data” is appropriately referred to as “conveying time data”.

  The deterioration degree determination unit 26f determines the degree of deterioration of the conveyance performance of the conveyance roller 23 by using a plurality of (multiple times) conveyance time data measured by the conveyance speed measurement unit 26e for each conveyance roller 23. To do. In the present embodiment, the deterioration degree determination unit 26f obtains the frequency at which the conveyance time data has exceeded a predetermined lifetime determination time within the predetermined period immediately before [for example, the past M sheets (M is an integer of 2 or more)] If this frequency is less than the predetermined threshold, it is determined that the transport roller 23 has not reached the end of its life, and if the frequency is not less than the predetermined threshold, it is determined that the end of the life has been reached. More specifically, the deterioration degree determination unit 26f obtains the number of data that exceeds the life determination time among the transport time data for the past nine times, and if the number is less than 3, the life is not reached. If it is 3 or more, it is determined that the lifetime has been reached. Here, as the life determination time, a time between the design value of the sheet conveyance time and the jam determination time is set.

  The notification unit 26g notifies the degree of deterioration of the conveyance performance for each conveyance roller 23 determined by the deterioration degree determination unit 26f. In the present embodiment, the notification unit 26g notifies that when the deterioration degree determination unit 26f determines that the life of the transport roller 23 has reached the end of its life. Here, examples of the notification include notification to the user by displaying on an operation panel (not shown), and notification to a maintenance center provided outside via an appropriate communication line.

(Regarding the function of the deterioration degree determination unit 26f for improving the determination accuracy)
In addition to the above-described functions, the above-described deterioration degree determination unit 26f is roughly provided with two functions for determining the deterioration degree with higher accuracy. Hereinafter, these functions will be described in detail.

  First, the first function will be described. The sheet conveyance speed varies depending on the sheet size, material, thickness, and the like even with the same conveyance roller 23. For example, the larger the size and thickness, the greater the load and the slower the conveyance speed. For this reason, if the conveyance time data measured for various types of sheets are used without being distinguished, the degree of deterioration cannot be accurately determined. For example, when a sheet with poor transportability is used, the degree of deterioration is determined to be large, while when a sheet with good transportability is used, the degree of deterioration is determined to be small.

  In the present embodiment, there are a plurality of target transport speeds. Therefore, it is inappropriate to use the transport time data measured at various target transport speeds without distinguishing them.

  Therefore, in the present embodiment, the deterioration degree determination unit 26f uses the conveyance time data measured by the conveyance speed measurement unit 26e for each sheet type and each target conveyance speed, and uses each sheet type and target value. The degree of deterioration is determined for each conveyance speed. At this time, the deterioration degree determination unit 26f uses a life determination time set in advance for each type of sheet and each target conveyance speed for determination.

  Specifically, the deterioration degree determination unit 26f determines the conveyance time data for each conveyance roller 23 for each sheet type based on the setting set by the sheet type setting unit 26b or the detection result of the sheet type detection unit 26c. And it distinguishes for every target conveyance speed, and it hold | maintains in a conveyance time data holding table. FIG. 3 is a diagram illustrating an example of contents held in the transport time data holding table. In the drawing, the conveyance time data is held separately for each sheet size and each target conveyance speed. In this embodiment, since it is only necessary to have the transport time data for the past nine times, the deterioration degree determination unit 26f performs a new transport when the transport time data for the past nine times is held in the transport time data holding table. When time data is obtained, the oldest transport time data is erased and new transport time data is written.

  Further, the deterioration degree determination unit 26f holds a life determination time preset for each type of sheet and each target conveyance speed in the life determination time management table. FIG. 4 is a diagram illustrating an example of the contents held in the life determination time management table. In the figure, the lifetime determination time set for each sheet size and each target conveyance speed is held.

  Then, the deterioration degree determination unit 26f refers to the conveyance time data holding table and the life determination time management table, and for each conveyance roller 23, the conveyance time data for the past nine times for each sheet type and each target conveyance speed. Among them, the number of data exceeding the lifetime determination time is obtained, and if the number is less than 3, it is determined that the lifetime has not been reached, and if it is 3 or more, it is determined that the lifetime has been reached.

  Next, the second function will be described. As described above, for example, when a piece of paper remains on the conveyance path 21 after the jam processing, the sheet conveyance time becomes long, and a sudden jam that does not depend on the deterioration of the conveyance capability of the conveyance roller 23 may occur. Further, a driving roller 23a is provided on the apparatus main body side, and a cover side driven roller 23b is provided on the apparatus main body so as to be openable and closable. When the cover is closed, the driven roller 23b comes into pressure contact with the driving roller 23a and opens the cover. In the image forming apparatus having the configuration in which the pressure contact is released, if the cover is not closed properly, the contact pressure may be insufficient and a sudden jam may occur. At this time, the conveyance speed measuring unit 26e measures conveyance time data having a very large value, but this is not caused by the deterioration of the conveyance roller 23. Therefore, when the conveyance time data is used for the determination. Therefore, the determination accuracy of the deterioration degree is deteriorated. For example, when sudden jams occur frequently, it is erroneously determined that the transport roller 23 has reached the end of its life.

  Therefore, in the present embodiment, when the deterioration degree determination unit 26f detects a predetermined event in which the conveyance time data measured by the conveyance speed measurement unit 26e is likely to be inappropriate data for determination, measurement is performed at that time. Disregarded transport time data. That is, the transport time data is discarded as noise and is not used for determining the degree of deterioration.

  As the predetermined event, for example, in addition to the sudden jam described above, the sheet type set by the user does not match the detected sheet type (sheet type mismatch). This is because it is unknown which is correct between the user setting and the detection result, and the sheet type is unknown, so that the conveyance time data cannot be used separately for each sheet type.

  Hereinafter, the ignorance of the conveyance time data by the deterioration degree determination unit 26f will be described separately for the sudden jam and the sheet type mismatch.

<Sudden Jam>
When a jam occurs, that is, when a jam is detected by the jam detection unit 26d, the deterioration degree determination unit 26f determines whether or not the jam is a sudden jam that is not caused by the deterioration of the transport roller 23. If it is determined that the jam occurs, the transport time data measured when the jam occurs is ignored. More specifically, in the present embodiment, when the jam occurs, the deterioration degree determination unit 26f is based on the conveyance time data immediately before the jam, and a degradation type (abrasion type) jam caused by the degradation of the conveyance roller 23. If it is determined that the jam is not a deteriorated jam, it is determined that the jam is a sudden jam.

  Here, the “conveying time data immediately before that”, that is, the conveying time data used for determining whether or not the deterioration type jam may include conveying time data measured in the print job in which the jam occurs. However, since the transport time data measured in the print job may be measured in a mechanical environment where a sudden jam occurs, the transport time data measured in the print job is excluded. It is preferable.

Further, the conveyance roller 23 to be determined as to whether or not it is a deteriorated jam is as follows. Here, a case where a jam is detected because the sensor 25 _N does not detect the arrival of the sheet will be described as an example. In the configuration in which the above-described first jam detection method is employed, it is considered that there is a cause of jam between the sensor 25 _N-1 and the sensor 25 _N , and therefore the transport roller 23 _N-1 is the object of determination. . In the configuration in which the above-described second jam detection method is adopted, it is considered that there is a cause of jam between the feed roller 22 and the sensor 25 _N, so that the transport rollers 23 ₁ , 23 _{2 ,. -1} is the target of judgment.

Further, the “transport time data measured at the time of occurrence of the jam”, that is, the transport time data to be ignored is as follows. Here, a case where a jam is detected because the sensor 25 _N does not detect the arrival of the sheet will be described as an example. In the configuration in which the above-described first jam detection method is adopted, it is considered that there is a cause of the jam between the sensor 25 _N-1 and the sensor 25 _N. Therefore, the conveyance roller 23 is at least in a print job in which the jam has occurred. _The transport time data measured for _N-1 is ignored. In the configuration in which the above-described second jam detection method is employed, it is considered that there is a cause of jam between the feed roller 22 and the sensor 25 _N. Therefore, at least in the print job in which the jam has occurred, the transport rollers 23 ₁ , The transport time data measured for 23 ₂ ,..., 23 _N−1 are ignored. In view of the fact that the machine environment was such that a sudden jam occurred, regardless of which jam detection method was used, all the conveyances measured in the print job in which the jam occurred. It is also preferred that time data be ignored.

In the present embodiment, the first jam detection method is adopted, and when the sensor 25 _N detects a jam, the deterioration degree determination unit 26 f performs the transport time data (for the past two times for the transport roller 23 _N-1 ( (Excluding those measured in the print job) and a predetermined threshold value, and if both are equal to or higher than the predetermined threshold value, it is determined that the jam is deteriorated, and if either is lower than the predetermined threshold value, the sudden type Judge as jam. When the deterioration degree determination unit 26f determines that the jam is a sudden jam, it ignores all transport time data measured in the print job (discards as noise).

<Sheet type mismatch>
When the deterioration degree determination unit 26f detects a mismatch between the sheet type set by the sheet type setting unit 26b and the sheet type detected by the sheet type detection unit 26c, the deterioration degree determination unit 26f measures the sheet where the mismatch is detected. Ignore the transfer time data.

  For example, when the sheet type set by the user is OHP but the detected sheet type is paper, the deterioration degree determination unit 26f measures the sheet detected as the paper. Ignore the transfer time data. When a sheet type mismatch is detected for a specific sheet in a print job for printing a plurality of sheets continuously, at least the transport time data measured for the specific sheet may be ignored. It is also preferable to ignore all transport time data that has been made.

  FIG. 5 is a flowchart showing an operation procedure of the control unit 26 of the sheet conveying apparatus 20 according to the present embodiment. Hereinafter, the operation of the control unit 26 will be specifically described with reference to FIG.

  When receiving a print instruction from a user, a personal computer, or the like, the control unit 26 determines a target conveyance speed based on a predetermined condition, and starts sheet conveyance control (S11). Here, it is assumed that the target transport speed is set to 208 mm / s. Further, it is assumed that the set number of prints related to the print instruction is 10, and the sheet type setting unit 26b receives the setting of the sheet size “A4L” from the user.

  In the sheet conveyance control, the roller drive control unit 26a controls the rotational drive of the rollers 22, 23, and 24 so that ten sheets flow through the conveyance path 21 at a conveyance speed of 208 mm / s with a predetermined interval. . The conveyance speed measurement unit 26e measures conveyance time data for each sheet for each conveyance roller 23. The sheet type detection unit 26 c detects the sheet type for each sheet passing through the conveyance path 21. The jam detector 26d monitors the output of each sensor 25 and detects a jam.

  If ten sheets have been printed without the jam detection unit 26d detecting a jam after the start of the sheet conveyance control (S12: NO, S13: YES), the control unit 26 stops the sheet conveyance control (S14). ). Then, the deterioration degree determination unit 26f determines whether or not the sheet type set by the sheet type setting unit 26b and the sheet type detected by the sheet type detection unit 26c do not match (S15).

  When it is determined that they are not inconsistent (S15: NO), the deterioration degree determination unit 26c obtains the latest nine data among the ten conveyance time data measured by the conveyance speed measurement unit 26e for each conveyance roller 23. Then, it is written in the column of (sheet size A4L, target conveyance speed 208 mm / s) of the conveyance time data holding table (S16). Then, the deterioration degree determination unit 26f, for each conveyance roller 23, the conveyance time data for the past nine times held in the column (sheet size A4L, target conveyance speed 208 mm / s) of the conveyance time data holding table, and the lifetime. Based on the frequency at which the conveyance time data exceeds the lifetime determination time, the conveyance roller is compared with the lifetime determination time held in the column (sheet size A4L, target conveyance speed 208 mm / s) of the determination time management table. It is determined whether 23 has reached the end of its life (S17). When it is determined that one of the transport rollers 23 has reached the end of life (S17: YES), the notification unit 26g prompts the replacement of the transport roller 23 determined to have reached the determination result or end of life. Is displayed on the operation panel (S18).

  When it is determined in step S15 that they do not match (S15: YES), the control unit 26 ends the print job. Accordingly, the transport time data measured in the print job is not written in the transport time data holding table.

  If a jam is detected by the jam detection unit 26d after the start of sheet conveyance control and before printing of 10 sheets is completed (S12: YES), the control unit 26 stops the sheet conveyance control (S19). Then, the deterioration degree determination unit 26f determines whether or not the jam is a sudden jam (S20). When it is determined that the jam is not a sudden jam (S20: NO), the process proceeds to step S16, and the conveyance time data Write and determine the degree of deterioration. On the other hand, when it is determined that it is a sudden jam (S20: YES), the print job is terminated. Accordingly, the transport time data measured in the print job is not written in the transport time data holding table.

The operation of the control unit 26 in one print job has been described above. Here, a long period from the start of use of the transport roller 23 to the end of its life will be considered. FIG. 6 is a diagram illustrating an example of the transition of the sheet conveyance time accompanying the increase in the number of sheet conveyances. In FIG. 6, the horizontal axis represents the number of sheet conveyances (number of sheets) at the target conveyance speed of 208 mm / s and the sheet size A4L, and the vertical axis represents the sheet conveyance time in the section P _N −P _{N + 1} . The time t1 is a design value of the sheet conveyance time in the section P _N −P _{N + 1} , the time t2 is the life determination time for the conveyance roller 23 _N , and the time t3 is the section P _N −P. _This is the jam detection time at _{N + 1} . As shown in the life determination time management table of FIG. 4, the time t2 is {(jam detection time−design value) × 70% + design value}. A solid line L indicates a measured value of the sheet conveyance time, that is, conveyance time data.

  As can be seen from the solid line L in FIG. 6, as the number of sheet conveyance increases, the sheet conveyance time becomes longer. This is due to a decrease in the coefficient of friction on the surface of the transport roller 23 due to wear on the surface of the transport roller 23 or adhesion of paper powder to the surface of the transport roller 23. In FIG. 6, peaks p1 and p2 indicate transport time data at the time of jam occurrence, but such a sudden jam is ignored as noise. In the hatched areas A1 and A2 in FIG. 6, the frequency at which the conveyance time data exceeds the lifetime determination time is high, and it is determined that the conveyance roller 23 has reached the lifetime, and this is notified. Note that the sheet conveyance time is temporarily shortened in the period between the shaded areas A1 and A2, but this is because, for example, the surface of the conveyance roller 23 is wiped.

  As described above, in this embodiment, the conveyance speed data indicating the conveyance speed of the sheet by the conveyance roller is measured, and the degree of deterioration of the conveyance performance of the conveyance roller is determined using the plurality of measured conveyance speed data. In the sheet conveying apparatus, when a predetermined event that is highly likely to cause the measured conveyance speed data to be inappropriate for determination is detected, the conveyance speed data measured at that time is ignored. For this reason, according to the present embodiment, it is possible to avoid deterioration in determination accuracy due to use of data inappropriate for determination in determination, and accurately determine the degree of deterioration in the conveyance performance of the conveyance roller. Can do. As a result, it is possible to accurately determine the life of the transport roller, and to prevent the transport roller from being erroneously replaced before reaching the life.

  Specifically, in the present embodiment, when a jam occurs, it is determined whether or not the jam is a sudden jam that is not caused by the deterioration of the conveyance roller. Ignore the transport speed data measured at the time of occurrence. For this reason, according to the present embodiment, it is possible to avoid the deterioration of the determination accuracy due to the use of the conveyance speed data measured in a mechanical environment in which a sudden jam occurs, and the conveyance performance of the conveyance roller can be avoided. The degree of deterioration can be accurately determined. For example, when a piece of paper remains on the conveyance path after the jam processing, it is possible to prevent the conveyance roller from being deteriorated erroneously and the conveyance roller from being erroneously replaced before reaching the end of its life. it can. Further, in this case, when a jam occurs, it is determined whether or not the jam is a deterioration type jam due to the deterioration of the transport roller based on the immediately preceding transport speed data. It is possible to determine whether or not it is a sudden jam with a simple configuration.

  Further, according to the present embodiment, the conveyance speed data is distinguished and used for each sheet type, and the degree of deterioration of the conveyance roller is determined for each sheet type, so that various types of sheets having different conveyance properties are used. It is possible to avoid the deterioration of the determination accuracy due to the batch use of the transfer speed data, and to accurately determine the deterioration degree of the transfer performance of the transfer roller.

  Further, in the present embodiment, the conveyance speed data is distinguished for each sheet type, and in the configuration for determining the deterioration degree of the conveyance roller for each sheet type, the sheet type set by the user is actually set. When a mismatch with the detected sheet type is detected, the conveyance speed data measured for the sheet where the mismatch is detected is ignored. For this reason, it is possible to avoid the deterioration of the determination accuracy due to the use of the conveyance speed data for the unclear sheet, and it is possible to accurately determine the degree of deterioration of the conveyance performance of the conveyance roller.

[Second Embodiment]
Hereinafter, an image forming apparatus 200 according to the second embodiment will be described. Since this image forming apparatus 200 is almost the same as the image forming apparatus 100 described above, common parts are denoted by the same reference numerals and description thereof is omitted. In the following description there will be described by focusing on the transport roller 23 _N.

Conveying speed measurement unit 26e, as the conveying speed data for conveyance rollers 23 _N, from the upstream end of the preceding sheet conveying path provided in the conveying rollers 23 _N upstream, by a predetermined distance downstream from the conveying roller 23 _N Measure the sheet transport time to a remote point. Here, the preceding-stage sheet conveyance path is a conveyance path including at least one sheet conveyance unit (such as a conveyance roller or a conveyance belt) provided on the upstream side of the conveyance roller 23 _N and a conveyance path 21 in a predetermined section. is there. In this embodiment, front sheet conveying path, the section conveying path 21 to the conveyance roller 23 _N from the conveying direction upstream end P _S, the feed roller 22 and the conveying roller _{23 i (i = 1~N-1} ) and Is a conveyance path including Then, the conveying speed measurement unit 26e, as the conveying speed data for conveyance rollers 23 _N, the time from the turn-on time of the motor for driving the feed roller 22 to the sensor 25 N _{+ 1} detects a sheet (sheet conveying time) taking measurement. In the following description, “conveying speed data” will be appropriately referred to as “conveying time data”.

Incidentally, preceding the sheet conveying path is not limited to the above, for example, front sheet conveying path of the conveying roller 23 _N includes a conveying path 21 of the section from the sheet conveying point P _N-1 to the transport roller 23 _N, conveying rollers 23 _{N -1} may be included. In this case, the conveying speed measurement unit 26e, as the conveying speed data for conveyance rollers 23 _N, to measure the sheet conveyance time from the sensor 25 _N-1 to the sensor 25 N _{+ 1.}

The conveyance time data for the conveyance roller 23 _N measured as described above is affected by the preceding sheet conveyance path. That is, if the delay in the sheet conveyance in the front sheet conveying path occurs, regardless of the deterioration condition of the transport roller 23 _N, the value of the transfer time data for the conveying roller 23 _N becomes large.

Therefore, in the present embodiment, the deterioration degree determination unit 26f detects a delay of a predetermined time or more in the conveyance of the sheet in the preceding sheet conveyance path as an event that the conveyance time data is likely to be inappropriate data for the determination. When the delay is detected, the conveyance time data measured for the sheet is ignored. Specifically, in this embodiment, the deterioration degree determination unit 26f, for each transfer time data measured for each sheet, from the turn-on time of the motor for driving the feed roller 22 until the sensor 25 _N detects the sheet If it is determined whether or not the predetermined time exceeds the predetermined threshold, and it is determined that the predetermined time exceeds the predetermined threshold, it is assumed that there is a delay in the preceding sheet conveyance path, and the conveyance time data measured for the sheet Ignore (throw away as noise).

  As described above, in the present embodiment, as the conveyance speed data, the sheet conveyance time from the upstream end of the preceding sheet conveyance path provided on the upstream side of the conveyance roller to a point separated by a predetermined distance from the conveyance roller to the downstream side. In the measurement configuration, when a delay of a predetermined time or more of sheet conveyance in the preceding sheet conveyance path is detected, the conveyance speed data measured for the sheet is ignored. For this reason, according to the present embodiment, it is possible to avoid deterioration in determination accuracy due to the use of the conveyance speed data affected by the delay of sheet conveyance in the preceding sheet conveyance path, and to accurately determine the degree of deterioration of the conveyance roller. It is possible to make a good judgment. For example, when the transport roller included in the preceding sheet transport path is worn, the deterioration degree of the transport performance of the transport roller located downstream is erroneously determined to be wrong, and the transport roller is erroneously replaced before the end of its service life. It can be avoided.

  In addition, this invention is not limited to the said embodiment, It can change variously within the range which does not deviate from the summary of this invention. For example, the number and installation positions of the sensors 25 can be appropriately set as long as the sheet conveyance speed by the conveyance roller 23 can be measured. For example, in order to accurately measure the transport speed, it is preferable that sensors are provided at two points on the downstream side of the target transport roller 23. Further, when there is one transport roller 23, it is only necessary to install one sensor 25 on the downstream side of at least the transport roller 23.

  Further, as a method for measuring the conveyance speed, a method of measuring the sheet conveyance time between two points as in the above embodiment is preferable because the configuration is simple. However, the method is not limited to this, and other methods are also available. Can also be adopted.

  Further, in the above embodiment, the deterioration degree determination unit 26f performs a two-stage determination as to whether or not the life of the transport roller 23 has reached the end of its life, but determines the deterioration degree in multiple stages. Also good. For example, the ratio of the conveyance speed data exceeding the predetermined threshold for the past 20 times may be calculated and this ratio may be notified, or the average value of the conveyance speed data for the past 20 times may be calculated and the average value notified. Also good.

  Further, in the above embodiment, when a jam occurs, it is determined whether or not the jam is a sudden jam by determining whether or not the jam is a degraded jam based on the immediately preceding conveyance measure data. It is also possible to determine by other methods.

1 is a schematic configuration diagram of an image forming apparatus including a sheet conveying device according to an embodiment. It is a block diagram which shows the function structure of the control part of FIG. It is a figure which shows an example of the holding content of a conveyance time data holding table. It is a figure which shows an example of the holding content of a lifetime determination time management table. 6 is a flowchart illustrating an operation procedure of a control unit of the sheet conveying apparatus according to the embodiment. FIG. 10 is a diagram illustrating an example of a transition of sheet conveyance time with an increase in the number of sheet conveyances.

Explanation of symbols

1 paper tray 2 discharge tray, 10 image forming unit, 20 a sheet conveying apparatus, 21 conveyance path, 22 a feed roller, 23 _1, 23 _2, · · ·, 23 _N conveying roller, 24 the discharge roller, 25 _1, 25 ₂ ,..., 25 _{N + 1} sensor, 26 control unit, 26a roller drive control unit, 26b sheet type setting unit, 26c sheet type detection unit, 26d jam detection unit, 26e conveyance speed measurement unit, 26f deterioration degree determination unit , 100 Image forming apparatus.

Claims (8)

A transport roller for transporting the sheet;
A conveyance speed measuring means for measuring conveyance speed data indicating the conveyance speed of the sheet by the conveyance roller;
Degradation degree determination means for determining the degree of deterioration of the conveyance performance of the conveyance roller using a plurality of conveyance speed data measured by the conveyance speed measurement means;
In a sheet conveying apparatus comprising:
The deterioration degree determining means, when detecting a predetermined event that the transport speed data measured by the transport speed measuring means is likely to be inappropriate data for the determination, is measured by the transport speed measuring means at that time. A sheet conveying apparatus characterized by ignoring the conveyed speed data. In the sheet conveying apparatus according to claim 1,
When the jam occurs, the deterioration degree determination means determines whether or not the jam is a sudden jam that is not caused by the deterioration of the conveyance roller. If the jam is determined to be a sudden jam, the measurement is performed when the jam occurs. A sheet conveying apparatus ignoring conveyed conveyance speed data. In the sheet conveying apparatus according to claim 2,
When the jam occurs, the deterioration degree determination unit determines whether or not the jam is a sudden jam based on the immediately preceding conveyance speed data. In the sheet conveying apparatus according to claim 1,
The conveyance speed measurement unit is configured to calculate, as the conveyance speed data, a sheet conveyance time from an upstream end of a preceding sheet conveyance path provided on the upstream side of the conveyance roller to a point away from the conveyance roller by a predetermined distance. Measure and
When the deterioration degree determination unit detects a delay of a predetermined time or more of sheet conveyance in the preceding sheet conveyance path, the sheet conveyance device ignores conveyance speed data measured for the sheet. In the sheet conveying apparatus according to any one of claims 1 to 4,
The sheet conveyance device, wherein the deterioration degree determination means distinguishes and uses the conveyance speed data for each sheet type, and determines the deterioration degree for each sheet type. In the sheet conveying apparatus according to claim 5,
Sheet type setting means for accepting setting of the type of sheet to be conveyed;
A sheet type detecting means for detecting the type of the sheet being actually conveyed,
When the deterioration degree determination unit detects a mismatch between the type set by the sheet type setting unit and the type detected by the sheet type detection unit, the conveyance speed data measured for the sheet in which the mismatch is detected Is a sheet conveying apparatus characterized by ignoring. A transport roller for transporting the sheet;
A conveyance speed measuring means for measuring conveyance speed data indicating the conveyance speed of the sheet by the conveyance roller;
Degradation degree determination means for determining the degree of deterioration of the conveyance performance of the conveyance roller using a plurality of conveyance speed data measured by the conveyance speed measurement means;
In a sheet conveying apparatus comprising:
The sheet conveyance device, wherein the deterioration degree determination means distinguishes and uses the conveyance speed data for each sheet type, and determines the deterioration degree for each sheet type. An image forming apparatus comprising the sheet conveying device according to claim 1.

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