Image forming apparatus and image forming system

Abstract

To improve maintenance efficiency. [Solution] An image forming apparatus comprising: an apparatus body; a transport unit detachably provided to the apparatus body, the transport unit having a rotating body for transporting sheets; a drive source that generates a driving force for driving the rotating body; a notification unit capable of notifying information that the transport unit is not properly attached to the apparatus body; and a control unit that controls the drive source and the notification unit, wherein the control unit acquires the load of the drive source corresponding to each of the multiple sheets being transported, and controls the notification unit to notify information when a sheet being transported jams in a section where the load of the drive source is less than a predetermined threshold.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus and an image forming system including the same.

Background Art

[0002] Conventionally, an image forming apparatus has been proposed that includes a device main body and a detachable unit that is detachable from the device main body, such as a developing unit, a conveyance belt unit, and a fixing unit (see Patent Document 1). When communication with a storage unit provided in the detachable unit cannot be performed, this image forming apparatus executes a detachable unit presence / absence detection process. In the detachable unit presence / absence detection process, the presence or absence of the detachable unit is determined based on the magnitude of the load torque of a motor that drives the detachable unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, when a detachable unit having a conveyance roller is not properly attached to the device main body, a jam occurs in which the sheet stays in the conveyance path. However, the cause of such a jam is not only due to the detachable unit not being properly attached to the device main body, but there is also a possibility of a defect in the image forming apparatus itself. If the cause of the jam can be identified, the maintenance efficiency of the image forming apparatus can be improved.

[0005] Therefore, an object of the present invention is to provide an image forming apparatus capable of improving maintenance efficiency and an image forming system including the same.

Means for Solving the Problems

[0006] One aspect of the present invention is an image forming apparatus comprising: an apparatus body; a transport unit detachably provided to the apparatus body, the transport unit having a rotating body for transporting sheets; a drive source for generating a driving force to drive the rotating body; a notification unit capable of notifying information that the transport unit is not properly attached to the apparatus body; and a control unit for controlling the drive source and the notification unit, wherein the control unit acquires the load of the drive source corresponding to each of a plurality of sheets being transported, and controls the notification unit to notify the information when a sheet being transported jams in a section where the load of the drive source is less than a predetermined threshold.

[0007] Another aspect of the present invention is an image forming apparatus comprising: an apparatus body; a transport unit detachably provided to the apparatus body, the transport unit having a rotating body for transporting sheets; a sheet detection unit for detecting sheets; a notification unit capable of notifying information that the transport unit is not properly attached to the apparatus body; and a control unit for controlling the notification unit, wherein the control unit acquires the time from when each of a plurality of transported sheets is fed until it reaches the sheet detection unit, and controls the notification unit to notify the information if a sheet jams during a section in which the time is shorter than a predetermined threshold.

[0008] Another aspect of the present invention is an image forming system comprising an image forming apparatus and a server capable of communicating with the image forming apparatus via a network, wherein the image forming apparatus comprises an apparatus body, a transport unit detachably provided to the apparatus body, the transport unit having a rotating body for transporting sheets, and a drive source that generates a driving force for driving the rotating body, and a notification unit capable of notifying information that the transport unit is not properly attached to the apparatus body, and a control unit provided in either the image forming apparatus or the server, wherein the control unit acquires the load of the drive source corresponding to each of a plurality of sheets transported to the image forming apparatus, and outputs a signal to operate the notification unit to notify the information when a sheet jams in a section where the load of the drive source is less than a predetermined threshold.

[0009] Another aspect of the present invention is an image forming system comprising an image forming apparatus and a server capable of communicating with the image forming apparatus via a network, wherein the image forming apparatus comprises an apparatus body, a transport unit detachably provided to the apparatus body, the transport unit having a rotating body for transporting sheets, and a sheet detection unit for detecting sheets, and a notification unit capable of notifying information that the transport unit is not properly attached to the apparatus body, and a control unit provided in either the image forming apparatus or the server, wherein the control unit acquires the time from when each of a plurality of transported sheets is fed until it reaches the sheet detection unit, and outputs a signal to operate the notification unit to notify the information if a sheet is jammed during a section in which the time is shorter than a predetermined threshold. [Effects of the Invention]

[0010] According to the present invention, maintenance efficiency can be improved. [Brief explanation of the drawing]

[0011] [Figure 1](a) is an overall schematic diagram showing an image forming apparatus according to the first embodiment, and (b) is a schematic cross-sectional view showing the image forming apparatus with the right door unit open. [Figure 2] (a) is a left side view showing the separation roller unit, (b) is a front view showing the separation roller unit, and (c) is a right side view showing the separation roller unit. [Figure 3] (a) is a front view showing the separation roller unit attached to the holder locking lever, (b) is a front view showing the holder locking lever moved to the separated position, and (c) is a front view showing the separation roller unit removed from the holder locking lever. [Figure 4] (a) is a plan view showing the separation roller unit properly attached to the main body of the device, (b) is a plan view showing the separation roller unit not attached to the main body of the device, and (c) is a plan view showing the separation roller unit incorrectly set on the main body of the device. [Figure 5] (a) shows two sheets being transported toward the separation nip, (b) shows the two sheets having reached the separation nip, and (c) shows the top sheet being separated from the bottom sheet and transported. [Figure 6] A block diagram showing the control system of an image forming system. [Figure 7] A flowchart illustrating each process in the jam cause identification and control. [Figure 8] A graph showing the integrated value of the PWM signal used to detect setting errors in the separation roller unit. [Figure 9] A diagram showing a sheet feeding device according to a second embodiment. [Figure 10] A graph showing the sheet arrival time to detect setting errors in the separation roller unit. [Modes for carrying out the invention]

[0012] <First Embodiment> [Overall structure] First, the first embodiment of the present invention will be described. The image forming apparatus 100 according to this embodiment is an electrophotographic full-color laser beam printer. Note that the image forming apparatus includes a printer, a copier, a facsimile machine, and a multifunction machine, and refers to an apparatus that forms an image on a sheet used as a recording medium based on image information input from an external PC or image information read from a document. In addition, in addition to the main body having an image forming function, the image forming apparatus may be connected with accessory devices such as an optional feeder, an image reading device, and a sheet processing device. The entire system to which such accessory devices are connected is also a type of image forming apparatus.

[0013] FIG. 1(a) is an overall schematic view showing the image forming apparatus. As shown in FIG. 1(a), the image forming apparatus 100 has an image forming unit 100A that forms an image on a sheet S, a sheet feeding device 50, and a fixing device 40. The image forming unit 100A includes four process cartridges PY, PM, PC, and PK that form toner images of four colors: yellow (Y), magenta (M), cyan (C), and black (K), and a laser scanner 3.

[0014] Note that the four process cartridges PY, PM, PC, and PK have the same configuration except that the colors of the images they form are different. Therefore, only the configuration and the image forming process of the process cartridge PY will be described, and the description of the process cartridges PM, PC, and PK will be omitted.

[0015] The process cartridge PY includes a photosensitive drum 1, a charging roller (not shown), and a developing device 4 including a developing roller. The photosensitive drum 1 is formed by applying an organic photoconductive layer to the outer periphery of an aluminum cylinder and rotates by a photosensitive motor 93 (see FIG. 8). In addition, the image forming unit 100A is provided with an intermediate transfer belt 2 wound around a driving roller 2a and the like, and primary transfer rollers 106Y, 106M, 106C, and 106K are provided inside the intermediate transfer belt 2.

[0016] The fixing device 40 has a fixing roller 40a heated by a heater (not shown) and a pressure roller 40b that presses against the fixing roller 40a. The sheet feeding device 50 includes a cassette 14 that supports the sheet S, a pickup roller 11 as a feeding unit that feeds the sheet S, conveyance rollers 12 and separation rollers 13 that separate the sheets S fed by the pickup roller 11 one by one, and the like. The sheet includes paper such as paper and envelopes, plastic films such as overhead projector sheets (OHP), cloth, and the like.

[0017] Next, the image forming operation of the image forming apparatus 100 configured as described above will be described. When an image signal is input from a host computer 200 (see FIG. 8) or the like connected to the image forming apparatus 100 into the laser scanner 3, laser light corresponding to the image signal is irradiated from the laser scanner 3 onto the photosensitive drum 1 of the process cartridge PY.

[0018] At this time, the surface of the photosensitive drum 1 is uniformly charged to a predetermined polarity and potential in advance by a charging roller, and an electrostatic latent image is formed on the surface when the photosensitive drum 1 is irradiated with laser light from the laser scanner 3. The electrostatic latent image formed on the photosensitive drum 1 is developed by the developing device 4, and a yellow (Y) toner image is formed on the photosensitive drum 1.

[0019] Similarly, the photosensitive drums of the process cartridges PM, PC, and PK are also irradiated with laser light from the laser scanner 3, and magenta (M), cyan (C), and black (K) toner images are formed on the respective photosensitive drums. A transfer operation is performed in which the toner images of each color formed on the respective photosensitive drums are transferred onto the intermediate transfer belt 2 by the primary transfer rollers 106Y, 106M, 106C, and 106K. Then, the toner images transferred onto the intermediate transfer belt 2 are conveyed to the secondary transfer roller 105 by the intermediate transfer belt 2 rotated by the drive roller 2a. The image forming process for each color is performed at a timing when it is superimposed on the upstream toner image primarily transferred onto the intermediate transfer belt 2.

[0020] In parallel with this image formation process, the sheet S contained in the cassette 14 of the sheet feeding device 50 is fed out by the pickup roller 11. The sheet S is then transported to the registration roller pair 323 by the transport roller 12 and the separation roller 13, and the transport roller pair 412. The transport roller pair 412 has a drive roller 41 and a driven roller 42 that rotates in accordance with the drive roller 41. The registration roller pair 323 has a drive roller 32 and a driven roller 33 that rotates in accordance with the drive roller 32.

[0021] The sheet S, whose skew has been corrected by the registration roller pair 323, is transported by the registration roller pair 323 at a predetermined transport timing. Then, the full-color toner image on the intermediate transfer belt 2 is transferred to the sheet S by the secondary transfer bias applied to the secondary transfer roller 105.

[0022] The sheet S onto which the toner image has been transferred is subjected to predetermined heat and pressure by the fixing roller 40a and pressure roller 40b of the fixing device 40, causing the toner to melt and solidify (fix) to the sheet. After passing through the fixing device 40, the sheet S is discharged to the discharge tray 108 by the discharge roller pair 107.

[0023] [Separation Roller Unit] Next, the separation roller unit 20 will be described using Figures 1(b) to 4(c). Figure 1(b) is a schematic cross-sectional view showing the image forming apparatus 100 with the right door unit 15 open. Figure 2(a) is a left side view showing the separation roller unit 20, Figure 2(b) is a front view showing the separation roller unit 20, and Figure 2(c) is a right side view showing the separation roller unit 20. Figure 3(a) is a front view showing the separation roller unit 20 attached to the holder locking levers 22 and 23, and Figure 3(b) is a front view showing the holder locking levers 22 and 23 moved to the separated position. Figure 3(c) is a front view showing the separation roller unit 20 removed from the holder locking levers 22 and 23.

[0024] Figure 4(a) is a plan view showing the separation roller unit 20 properly attached to the device body 120, and Figure 4(b) is a plan view showing the separation roller unit 20 not attached to the device body 120. Figure 4(c) is a plan view showing the separation roller unit 20 incorrectly set on the device body 120.

[0025] As shown in Figure 1(b), the image forming apparatus 100 has a right door unit 15 that can be opened and closed relative to the apparatus body 120 around a pivot axis 15a, and a separation roller unit 20 including a separation roller 13. The separation roller unit 20, which serves as a transport unit, is detachably mounted to the apparatus body 120 and can be removed in the direction of arrow C when the right door unit 15 is open.

[0026] As shown in Figures 2(a) to (c), the separation roller unit 20 includes a separation holder 21 and a separation roller 13 as a rotating body rotatably supported by the separation holder 21. Separation holder bosses 21a, 21a protrude from one side of the separation holder 21 in the width direction W of the sheet, and separation holder bosses 21b, 21b protrude from the other side of the separation holder 21.

[0027] Furthermore, as shown in Figure 3(a), the sheet feeding device 50 of the image forming apparatus 100 includes a feeding guide 24 fixed to the apparatus body 120, and holder locking levers 22 and 23 that are supported so as to be movable in the width direction W relative to the feeding guide 24. The holder locking levers 22 and 23 are configured to be movable between a holding position, which is a position close to each other in the width direction W, and a separated position, which is a position far apart from each other.

[0028] As shown in Figure 3(a), the separation roller unit 20 is held in the device body 120 by the holder locking levers 22 and 23 located in the holding position, which hold the separation holder bosses 21a, 21a, 21b, and 21b. When removing the separation roller unit 20 from the device body 120, the holder locking levers 22 and 23 are moved to the separated position as shown in Figure 3(b). Specifically, the holder locking lever 22 is moved in the direction of arrow A shown in Figure 3(a), and the holder locking lever 23 is moved in the direction of arrow B shown in Figure 3(a). The holder locking levers 22 and 23 are biased by biasing members (not shown) in the opposite direction to arrow A and the opposite direction to arrow B, respectively.

[0029] When the holder locking levers 22 and 23 are positioned apart, the holder locking levers 22 and 23 release the holding of the separation holder bosses 21a, 21a, 21b, 21b. In this state, as shown in Figures 1(b) and 3(b)(c), the separation roller unit 20 is moved in the direction of arrow C, thereby removing the separation roller unit 20 from the device body 120.

[0030] Figure 4(a) shows the separation roller unit 20 properly attached to the device body 120. At this time, the separation holder bosses 21a, 21a, 21b, 21b are securely held by the holder locking levers 22, 23 located in the holding position. When the separation roller unit 20 is properly attached to the device body 120, the separation roller 13 contacts the conveyor roller 12 to form a separation nip N (see Figure 5(a)) that separates the sheets one by one.

[0031] As shown in Figure 4(b), when the separation roller unit 20 is not attached to the main body 120, the separation holder 21 performs part of the function of the sheet transport path, resulting in a gap in the transport path in the central part in the width direction W. Furthermore, since the separation roller 13 of the separation roller unit 20 is absent, it is not possible to form a separation nip with the transport roller 12 and the separation roller 13. Therefore, when the separation roller unit 20 is not attached to the main body 120, the sheet fed by the pickup roller 11 is transported by the transport force of the pickup roller 11 alone until it reaches the transport roller pair 412. In this case, since a separation nip is not formed, the sheet fed by the pickup roller 11 cannot be separated one by one, and there is a risk of jamming due to the sheets being fed in multiples.

[0032] Furthermore, as shown in Figure 4(c), the state in which the separation roller unit 20 is installed in a position shifted from the normal position shown in Figure 4(a) is referred to as the state in which the separation roller unit 20 is installed incorrectly. This state is also simply called the incorrect installation state. Note that the incorrect installation state may also include the state in which the separation roller unit 20 is not installed at all. In this case, the separation holder bosses 21a, 21a, 21b, 21b of the separation roller unit 20 are not properly held by the holder locking levers 22, 23. As a result, the separation roller unit 20 is tilted at an angle compared to the state in which it is installed correctly, as shown in Figure 4(a).

[0033] The mis-set condition of the separation roller unit 20 is not resolved even when the right door unit 15 is closed. Furthermore, the separation nip is not formed correctly, and the sheets are transported with misalignment between the transport roller 12 and the separation roller 13. This misalignment may cause the sheets to travel at an angle and jam. In addition, the sheets fed by the pickup roller 11 cannot be separated one by one, and there is a risk of jams occurring due to sheets being fed in multiples.

[0034] [Mechanism for separating sheets one by one] Next, using Figures 5(a) to 5(c), the mechanism by which the sheets are separated one by one by the separation nip N formed by the conveying roller 12 and the separation roller 13 will be explained. Figure 5(a) shows the two sheets S1 and S2 being conveyed toward the separation nip N, and Figure 5(b) shows the two sheets S1 and S2 having reached the separation nip N. Figure 5(c) shows the uppermost sheet S1 being separated from the lower sheet S2 and conveyed.

[0035] As shown in Figure 5(a), consider the case where multiple sheets are conveyed by the pickup roller 11. In Figures 5(a) to (c), for illustrative purposes, we will explain the case where two sheets, the uppermost sheet S1 and the sheet below it S2, are fed by the pickup roller 11. The separation roller 13 has a built-in torque limiter 13a that is driven and connected to the separation roller 13. Note that the torque limiter 13a does not necessarily have to be built into the separation roller 13; for example, it may be provided on the rotating shaft to which the separation roller 13 is fixed.

[0036] As shown in Figure 5(a), before sheets S1 and S2 reach the separation nip N, the pickup roller 11 and the transport roller 12 rotate in the CCW direction, and the separation roller 13 rotates in the CW direction opposite to the CCW direction by being driven by the transport roller 12. At this time, the frictional force at the separation nip N is greater than the limit value of the torque limiter 13a, so the torque limiter 13a slips.

[0037] As shown in Figure 5(b), when sheets S1 and S2 reach the separation nip N, the uppermost sheet S1 is conveyed by the conveyor roller 12. On the other hand, since the frictional force between sheets S1 and S2 is less than the limit value of the torque limiter 13a, sheet S2 is stopped by the separation roller 13, which is in a stationary state. As a result, as shown in Figure 5(c), only sheet S1 is conveyed while sliding against sheet S2, and the multiple sheets S1 and S2 that have been conveyed to the separation nip N are separated and conveyed one by one.

[0038] [Control System] Figure 6 is a block diagram showing the control system of the image forming system 500 according to this embodiment. As shown in Figure 6, the image forming system 500 as a malfunction diagnosis system includes an image forming apparatus 100, a host computer 200, a server 300, and a maintenance management computer 400. The image forming apparatus 100, the host computer 200, the server 300, and the maintenance management computer 400 are configured to communicate with each other, for example, via a network.

[0039] The host computer 200 includes a control unit 201 and an operation display unit 202. The control unit 201 includes a CPU (Central Processing Unit) and performs various processes by executing a control program stored in a storage device (not shown). The operation display unit 202 includes a display, keyboard, mouse, etc., and provides a user interface. For example, in response to user operations on the operation display unit 202, the control unit 201 sends a print job including image data to the image forming apparatus 100, causing the image forming apparatus 100 to form an image based on the image data.

[0040] The image forming apparatus 100 includes a video controller 101, an operation display unit 102, a printer engine 103, and the like. The video controller 101 of the image forming apparatus 100 performs communication processing with the host computer 200, the server 300, and the maintenance management computer 400 managed by the dealer. When the video controller 101 receives a print job from the host computer 200, it controls the image forming by the printer engine 103 based on that print job.

[0041] The operation display unit 102 includes an operation panel and operation buttons, and provides a user interface. The printer engine 103 has a CPU 111, an engine control unit 110 including a ROM (Read Only Memory) 112 and a RAM (Random Access Memory) 113, and an I / O port 104. The ROM 112 is a non-volatile memory that holds and stores control programs and various data. Note that a rewritable non-volatile memory can be used instead of the ROM 112. The RAM 113 is a volatile memory that stores temporary data. The CPU 111 executes the control program stored in the ROM 112, and via the I / O port 104 controls each motor (91-95), which will be described later, to form an image on the sheet S.

[0042] The feed motor 91 is the drive source for the pickup roller 11, the transport roller 12, the transport roller pair 412, and the registration roller pair 323. The belt motor 92 is the drive source for the drive roller 2a that drives the intermediate transfer belt 2. The photoreceptor motor 93 is the drive source for each photoreceptor drum 1. The developing motor 94 is the drive source for the developing roller of each developing unit 4. The fuser motor 95 is the drive source for the pressure roller 40b of the fuser unit 40.

[0043] Furthermore, the engine control unit 110, which acts as a control unit, is connected to the transport sensor 90 via the IO port 104. One or more transport sensors 90 are provided in the transport path CP (see Figure 1(a)) through which the sheet of the device body 120 passes, and are capable of detecting the sheet.

[0044] The server 300 includes an arithmetic unit 310 as a control unit and a storage device 320. The arithmetic unit 310 includes one or more processors (CPUs) and performs various processes by executing control programs stored in the storage device 320. The storage device 320 includes any volatile and non-volatile storage devices. In addition to the programs executed by the arithmetic unit 310, the storage device 320 also stores data used by the arithmetic unit 310 in various processes. In this embodiment, the storage device 320 is a component of the server 300, but some or all of the data described below as being stored in the storage device 320 may be stored in an external device that the server 300 can access via a network.

[0045] The maintenance management computer 400, which functions as an information processing device, has a display unit 402 capable of displaying information. Based on information from the image forming apparatus 100 and the server 300, the maintenance management computer 400 can remotely instruct the user on how to resolve malfunctions, supply worn-out periodic replacement units, and arrange for on-site repairs of faulty parts at the user's location.

[0046] [Jam Cause Identification and Control] Next, the jam cause identification control will be explained using Figures 7 and 8. Figure 7 is a flowchart showing each process of the jam cause identification control. Figure 8 is a graph showing the integrated value of the PWM signal for detecting the occurrence of a setting error in the separation roller unit 20.

[0047] As shown in Figure 7, when jam cause identification control is initiated, the engine control unit 110 of the image forming apparatus 100 first determines whether or not a jam has occurred based on the detection result of the transport sensor 90 (step S11). For example, if a predetermined transport sensor 90 does not detect the sheet after a certain period of time has elapsed since the start of the printing job and the sheet has been fed by the pickup roller 11, the engine control unit 110 determines that a jam has occurred.

[0048] If it is determined that a jam has occurred (step S11: YES), the engine control unit 110 determines whether or not a mis-set condition of the separation roller unit 20 has been detected (step S12).

[0049] Here, using Figure 8, the method for detecting a mis-set state of the separation roller unit 20 in this embodiment will be explained. The separation roller 13 of the separation roller unit 20 is driven rotation by the transport roller 12. In this embodiment, the transport roller 12 is driven by a feed motor 91, which is composed of a DC brushless motor. That is, the feed motor 91, as a drive source, generates the driving force to drive the separation roller 13. The feed motor 91 is controlled based on a control signal from the engine control unit 110.

[0050] More specifically, the engine control unit 110 compares the target rotational speed of the feed motor with the rotational speed output from the speed detection unit of the feed motor 91, and generates and outputs a PWM signal. The PWM (Pulse Width Modulation) signal chops the drive current of the feed motor 91, thereby controlling the rotational speed of the feed motor 91. In other words, by repeatedly switching on and off at a constant frequency, the PWM signal controls the time the current flows and can adjust the average current supplied to the feed motor 91. When the duty cycle of the PWM signal (the proportion of the on state within the on-off cycle) is low, the feed motor 91 rotates at a low speed, and when the duty cycle of the PWM signal is high, the feed motor 91 rotates at a high speed. Note that the feed motor 91 may be composed of other motors such as a stepping motor.

[0051] When the load on the feed motor 91 is large, a momentary difference occurs between the rotational speed target value transmitted from the engine control unit 110 and the rotational speed output from the speed detection unit, and a PWM signal is generated to bring the actual rotational speed to the rotational speed target value. In other words, the integrated value of the PWM signal is larger when the transport load, i.e., the load on the feed motor 91, is large compared to when it is small.

[0052] Therefore, there is a correlation between the load on the feed motor 91 and the integrated value of the PWM signal. When the load on the feed motor 91 increases, the integrated value of the PWM signal also increases, and when the load on the feed motor 91 decreases, the integrated value of the PWM signal also decreases.

[0053] The horizontal axis in Figure 8 represents the page count, i.e., the total number of pages printed so far. The vertical axis in Figure 8 shows the integrated value of the PWM signal used to control the feed motor 91 (hereinafter simply referred to as the integrated value of the PWM signal) from the start of sheet feeding by the pickup roller 11 until a predetermined time. The predetermined time can be set to any time as long as it is before the next sheet is fed. The integrated value of the PWM signal is shown for each of the multiple sheets being transported, and it is the integrated value per page. The dashed line in Figure 8 is the threshold TH1 for determining whether or not the separation roller unit 20 is in a set error state.

[0054] As can be seen from Figure 8, from the start of the job until page count P1, or from page count P2 onwards, the integrated value of the PWM signal remains above the threshold TH1. When the separation roller unit 20 is properly attached to the main body 120, the load of the torque limiter 13a built into the separation roller 13 is applied to the feed motor 91. As a result, the integrated value of the PWM signal increases with the load on the feed motor 91, and the integrated value of the PWM signal is above the threshold TH1.

[0055] On the other hand, from page count P1 to page count P2, the integrated value of the PWM signal remains below the threshold TH1. When the separation roller unit 20 is in a set error state, the drive is not properly transmitted from the transport roller 12 to the separation roller 13, and the load of the torque limiter 13a built into the separation roller 13 is not applied to the feed motor 91. As a result, the integrated value of the PWM signal also decreases as the load on the feed motor 91 decreases, and the integrated value of the PWM signal is below the threshold TH1.

[0056] In this way, it is possible to determine whether the separation roller unit 20 is properly set or in a set-error state from the load of the feed motor 91, which is a value based on the integrated value of the PWM signal. In this embodiment, the engine control unit 110 acquires data of the integrated value of the PWM signal as shown in Figure 8. From this data, the engine control unit 110 identifies a section X, i.e., the section of page counts P1 to P2, in which it is determined that the separation roller unit 20 is in a set-error state.

[0057] The threshold TH1 is not limited to a fixed value and may be changed according to the printing mode. For example, the engine control unit 110 has multiple printing modes that are changed according to the attributes of the sheet being transported, such as the basis weight and thickness of the sheet. When transporting a sheet with a first basis weight, such as thin paper, a first printing mode is executed, in which the sheet is transported at a first speed. When transporting a sheet with a second basis weight greater than the first basis weight, such as thick paper, a second printing mode is executed, in which the sheet is transported at a second speed slower than the first speed. In this case, the threshold TH1 in the first printing mode is greater than the threshold TH1 in the second printing mode. In other words, the predetermined threshold TH1 can be said to be changed according to the attributes of the sheet being transported.

[0058] In this embodiment, as described above, it is possible to detect a mis-set state of the separation roller unit 20. Returning to the flowchart in Figure 7, if a mis-set state of the separation roller unit 20 is detected (step S12: YES), the engine control unit 110 determines whether or not there is a jam in section X (step S13). That is, if a sheet between page counts P2 and P3 jams, it is determined that there is a jam in section X.

[0059] If it is determined that there is a jam in section X (step S13: YES), the engine control unit 110 notifies information that the separation roller unit 20 is in a set-off state (step S14). The information that the separation roller unit 20 is in a set-off state is conveyed by message, voice, image, or any combination thereof, and is conveyed to at least one of the operation display units 102, 202 and display unit 402, which act as notification units. The information that the separation roller unit 20 is in a set-off state may be, for example, a message about a method for resolving the set-off state.

[0060] Furthermore, if a jam is not detected in step S11, if a mis-set state of the separation roller unit 20 is not detected in step S12, or if it is not determined in step S13 that a jam has occurred in section X, the jam cause identification control is terminated.

[0061] Furthermore, the processing in steps S13 and S14 is not limited to the engine control unit 110 of the image forming apparatus 100, but may also be performed by the control unit 201 of the host computer 200, the calculation unit 310 of the server 300, or the maintenance management computer 400. For example, if the calculation unit 310 of the server 300 determines, based on various analyses, that a jam has occurred in section X, it may notify the display unit 402 of the maintenance management computer 400 that the separation roller unit 20 is in a set error state. Processing by the server 300 enables more advanced statistical processing.

[0062] As described above, in this embodiment, by identifying the section X in which the separation roller unit 20 is in a set-misconfiguration state, the cause of a jam can be identified when one occurs. For example, if it is determined that the jam is in section X, the user can be notified of appropriate troubleshooting regarding the set-misconfiguration state. Conversely, if it is determined that the jam is in a section other than X, it can be determined that there is a malfunction in the image forming apparatus 100 itself, and the user can be notified accordingly. This improves the maintenance efficiency of the image forming apparatus 100.

[0063] Furthermore, the maintenance company using the maintenance management computer 400 does not need to dispatch a service technician to identify the cause of the jam. The maintenance company can then, for example, supply a separation roller unit 20 and resolve the problem by providing instructions on how to replace the separation roller unit 20 via remote means such as telephone. In this way, by identifying that the cause of the jam is a mis-set separation roller unit 20, unnecessary service dispatches can be suppressed, and service costs can be reduced.

[0064] In recent years, in the market for image forming equipment, such as laser printers, there has been an increase in opportunities for vendors to enter into maintenance contracts or usage-based contracts (for example, contracts where charges are based on the number of pages printed) with users. Under these contract types, service costs are included in the print price, making it important to reduce unnecessary dispatches to user sites and to efficiently resolve malfunctions.

[0065] Furthermore, if the image forming apparatus 100 has multiple cassettes 14, the accuracy of cause identification can be improved by adding the relationship between the location of the setting error in the separation roller unit 20 and the cassette 14 that fed the sheet when the jam occurred as a condition for identifying the cause. Specifically, when a jam occurs, if the integrated value of the PWM signal of the feed motor corresponding to the cassette 14 that fed the jammed sheet is less than or equal to the threshold TH1, it is determined that there is a high probability that the jam was caused by a setting error in the separation roller unit 20. This improves the accuracy of identifying the cause of jams.

[0066] Alternatively, a setting error in the separation roller unit 20 may be identified from the average change in the integrated value of the PWM signal before and after opening and closing the right door unit 15. In the configuration of this embodiment, the user cannot replace the separation roller unit 20 unless the right door unit 15 is opened. That is, a setting error in the separation roller unit 20 does not occur unless the right door unit 15 is opened, making it possible to identify the error in this way. In this case, it is possible to identify a setting error in the separation roller unit 20 more accurately than when the page count before and after opening and closing the right door unit 15 is not used.

[0067] <Second Embodiment> Next, a second embodiment of the present invention will be described. The second embodiment is configured to detect a mis-set state of the separation roller unit 20 using a different detection method than that of the first embodiment. For this reason, components similar to those in the first embodiment will not be shown in the illustration, or will be described using the same reference numerals in the illustration.

[0068] Figure 9 shows a sheet feeding device 150 according to a second embodiment. In Figure 9, the separation roller unit 20 has been removed from the device body 120 (see Figure 1(a)). As shown in Figure 9, the sheet feeding device 150 has a conveying sensor 90a and a register sensor 34 as sheet detection units. The conveying sensor 90a is provided near the conveying roller pair 412 and has a rotating part that rotates when pressed by a sheet, and a sensor part that switches on and off in accordance with the rotation of the rotating part. Similarly, the register sensor 34 has a rotating part that rotates when pressed by a sheet, and a sensor part that switches on and off in accordance with the rotation of the rotating part. These sensor parts are composed of, for example, optical sensors. The conveying sensor 90a and the register sensor 34 can detect sheets being conveyed along the conveying path CP.

[0069] The sheet fed from the cassette 14 by the pickup roller 11 passes through the transport path CP and is detected by the transport sensor 90a. Subsequently, the sheet's skew is corrected when it abuts against a shutter member (not shown) located immediately before the nip of the registration roller pair 323. After passing through the shutter member, the sheet is detected by the registration sensor 34 and an image is formed by the image forming unit 100A (see Figure 1(a)).

[0070] As described in the first embodiment, when the separation roller unit 20 is removed, the separation nip N is not formed, and the sheets are not separated one by one. As a result, the sheets below the uppermost sheet fed by the pickup roller 11 are transported downstream in the sheet transport direction from the position of the separation nip N. Figure 9 illustrates this situation.

[0071] Here, using Figure 10, the method for detecting a set error in the separation roller unit 20 in this embodiment will be explained. Figure 10 is a graph showing the arrival time of sheets for detecting the occurrence of a set error in the separation roller unit. The horizontal axis of Figure 10 represents the page count, i.e., the total number of pages printed so far. The vertical axis of Figure 10 represents the time from when the sheet feeding by the pickup roller 11 starts until the sheet reaches the transport sensor 90a (hereinafter simply referred to as arrival time). The arrival time is shown for each of the multiple sheets being transported. The dashed line in Figure 10 is the threshold TH2 for determining whether or not the separation roller unit 20 is in a set error state.

[0072] As can be seen from Figure 10, from the start of the job until page count P3, or from page count P4 onwards, the arrival time remains above the threshold TH2. When the separation roller unit 20 is properly attached to the main body 120, a separation nip N is formed, and the sheet fed by the pickup roller 11 to the uppermost sheet stops at the separation nip N. In this case, no sheet is fed from a position downstream of the separation nip N in the sheet transport direction. At this time, the arrival time is above the threshold TH2.

[0073] On the other hand, from page count P3 to page count P4, the arrival time remains below the threshold TH2. If the separation roller unit 20 is in a mis-set state (including being forgotten or misaligned), the separation nip N is not formed. As a result, subsequent sheets fed by the pickup roller 11 often stop downstream in the sheet transport direction beyond the position of the separation nip N. When this sheet is fed by the pickup roller 11, the arrival time is shorter compared to when the separation roller unit 20 is properly installed. Therefore, the arrival time is below the threshold TH2.

[0074] In this way, it is possible to determine from the arrival time described above whether the separation roller unit 20 is in a properly set state or in a set-error state. In this embodiment, the engine control unit 110 identifies a section Y, i.e., the section of page count P3 to P4, in which the separation roller unit 20 is determined to be in a set-error state, from the arrival time data shown in Figure 10.

[0075] The threshold TH2 is not limited to a fixed value and may be changed according to the printing mode. For example, the engine control unit 110 has multiple printing modes that are changed according to the attributes of the sheet being transported, such as the basis weight and thickness of the sheet. When transporting a sheet with a first basis weight, such as thin paper, a first printing mode is executed, in which the sheet is transported at a first speed. When transporting a sheet with a second basis weight greater than the first basis weight, such as thick paper, a second printing mode is executed, in which the sheet is transported at a second speed slower than the first speed. In this case, the threshold TH2 in the first printing mode is smaller than the threshold TH2 in the second printing mode. In other words, the predetermined threshold TH2 can be said to be changed according to the attributes of the sheet being transported.

[0076] In this embodiment, the control for identifying the cause of jamming is the same as in the first embodiment, and only the method for detecting the mis-set state of the separation roller unit 20 in step S12 shown in Figure 7 differs from the first embodiment. Therefore, the same effects as in the first embodiment can be achieved.

[0077] In this embodiment, the arrival time may be the time from the start of sheet feeding by the pickup roller 11 until the sheet reaches the register sensor 34.

[0078] Furthermore, although this embodiment describes a method for detecting a set error in the separation roller unit 20, it can be applied not only to the separation roller unit 20 but also to other conveying roller units. The conveying roller unit has conveying rollers that convey sheets through the conveying path CP and is detachably mounted on the main body 120 of the device. When the conveying roller unit is in a set error state, the time from a certain reference time to reaching the conveying sensor becomes longer than when it is set correctly because there is insufficient conveying force due to the absence of the conveying roller unit. Therefore, by calculating the page count for the section that exceeds a predetermined threshold, it is possible to identify the section in which the conveying unit is in a set error state.

[0079] <Other Embodiments> Furthermore, although the invention has been described using an electrophotographic image forming apparatus 100 in all of the embodiments described above, the present invention is not limited thereto. For example, the present invention can also be applied to an inkjet image forming apparatus that forms an image on a sheet by ejecting ink liquid from a nozzle.

[0080] The present invention can also be realized by supplying a program that implements one or more of the functions of the above embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0081] Summary of this disclosure This disclosure includes at least the following: (Composition 1) In an image forming apparatus, The main body of the device, A conveying unit detachably attached to the main body of the device, the conveying unit having a rotating body for conveying sheets, A drive source that generates a driving force for driving the rotating body, A notification unit capable of notifying information that the transport unit is not properly attached to the main body of the device, The system comprises a control unit that controls the drive source and the notification unit, The control unit acquires the load of the drive source corresponding to each of the multiple sheets being transported, and controls the notification unit to notify the information if a sheet jams while being transported in a section where the load of the drive source is less than a predetermined threshold. An image forming apparatus characterized by the following features. (Configuration 2) A feeding unit that feeds the sheets, The system further comprises a conveying roller for conveying the sheet fed by the aforementioned feeding unit, The rotating body, when the conveying unit is properly mounted on the main body of the device, contacts the conveying roller to form a separation nip that separates the sheets one by one, together with the conveying roller. The image forming apparatus according to configuration 1, characterized in that it is a picture forming apparatus. (Composition 3) The load on the drive source is a value based on the integrated value of the PWM signal used to control the drive source from the start of sheet feeding by the feeding unit until a predetermined time. The image forming apparatus according to configuration 2, characterized in that... (Composition 4) The transport unit includes a torque limiter that is driven and connected to the rotating body. The image forming apparatus according to configuration 2 or 3, characterized by the above. (Composition 5) When the transport unit is properly mounted on the main body of the device, the load on the drive source is greater than the predetermined threshold. An image forming apparatus according to any one of configurations 1 to 4, characterized by the above. (Composition 6) The control unit has multiple printing modes, The predetermined threshold is changed according to the plurality of print modes. An image forming apparatus according to any one of configurations 1 to 5, characterized by the above. (Composition 7) The predetermined threshold is changed according to the attributes of the sheet being transported. An image forming apparatus according to any one of configurations 1 to 5, characterized by the above. (Composition 8) In an image forming apparatus, The main body of the device, A conveying unit detachably attached to the main body of the device, the conveying unit having a rotating body for conveying sheets, A sheet detection unit that detects the sheet, A notification unit capable of notifying information that the transport unit is not properly attached to the main body of the device, The system includes a control unit that controls the notification unit, The control unit acquires the time from when each of the multiple sheets being transported is fed until it reaches the sheet detection unit, and controls the notification unit to notify the information if a sheet being transported in a section where the time is shorter than a predetermined threshold is jammed. An image forming apparatus characterized by the following features. (Composition 9) A feeding unit that feeds the sheets, The system further comprises a conveying roller for conveying the sheet fed by the aforementioned feeding unit, The rotating body, when the conveying unit is properly mounted on the main body of the device, contacts the conveying roller to form a separation nip that separates the sheets one by one, together with the conveying roller. The image forming apparatus according to configuration 8, characterized by the above. (Composition 10) The time during which the transport unit is properly mounted on the main body of the device is longer than the predetermined threshold. The image forming apparatus according to configuration 8 or 9, characterized by the above. (Composition 11) The control unit has multiple printing modes, The predetermined threshold is changed according to the plurality of print modes. An image forming apparatus according to any one of the configurations 8 to 10, characterized by the above. (Composition 12) The predetermined threshold is changed according to the attributes of the sheet being transported. An image forming apparatus according to any one of the configurations 8 to 11 characterized by the above. (Composition 13) In an image forming system comprising an image forming apparatus and a server capable of communicating with the image forming apparatus via a network, The image forming apparatus is The main body of the device, A conveying unit detachably attached to the main body of the device, the conveying unit having a rotating body for conveying sheets, It comprises a drive source that generates a driving force for driving the rotating body, A notification unit capable of notifying information that the transport unit is not properly attached to the main body of the device, The system comprises a control unit provided in either the image forming apparatus or the server, The control unit acquires the load of the drive source corresponding to each of the plurality of sheets transported to the image forming apparatus, and outputs a signal to operate the notification unit to notify the information if a sheet jams while being transported in a section where the load of the drive source is less than a predetermined threshold. An image forming system characterized by the following: (Composition 14) The server is further equipped with an information processing device that can communicate via a network, The notification unit is provided in at least one of the image forming apparatus and the information processing apparatus. The image forming system according to configuration 13, characterized by the features described above. (Composition 15) The control unit is provided in the server, The image forming system according to configuration 13 or 14, characterized by the above. (Composition 16) The image forming apparatus includes a feeding unit for feeding sheets and a conveying roller for transporting the sheets fed by the feeding unit. The rotating body, when the conveying unit is properly mounted on the main body of the device, contacts the conveying roller to form a separation nip that separates the sheets one by one, together with the conveying roller. An image forming system according to any one of configurations 13 to 15, characterized by the above. (Composition 17) The load on the drive source is a value based on the integrated value of the PWM signal used to control the drive source from the start of sheet feeding by the feeding unit until a predetermined time. The image forming system according to configuration 16, characterized by the features described above. (Composition 18) The transport unit includes a torque limiter that is driven and connected to the rotating body. The image forming system according to configuration 16 or 17, characterized by the above. (Composition 19) When the transport unit is properly mounted on the main body of the device, the load on the drive source is greater than the predetermined threshold. An image forming system according to any one of configurations 13 to 18, characterized by the above. (Composition 20) In an image forming system comprising an image forming apparatus and a server capable of communicating with the image forming apparatus via a network, The image forming apparatus is The main body of the device, A conveying unit detachably attached to the main body of the device, the conveying unit having a rotating body for conveying sheets, It has a sheet detection unit that detects the sheet, A notification unit capable of notifying information that the transport unit is not properly attached to the main body of the device, The system comprises a control unit provided in either the image forming apparatus or the server, The control unit acquires the time from when each of the multiple sheets being transported is fed until it reaches the sheet detection unit, and outputs a signal to operate the notification unit to notify the information if a sheet being transported jams in a section where the time is shorter than a predetermined threshold. An image forming system characterized by the following: (Composition 21) The server is further equipped with an information processing device that can communicate via a network, The notification unit is provided in at least one of the image forming apparatus and the information processing apparatus. The image forming system according to configuration 20, characterized in that... (Composition 22) The control unit is provided in the server, The image forming system according to configuration 20 or 21, characterized by the above. (Composition 23) A feeding unit that feeds the sheets, The system further comprises a conveying roller for conveying the sheet fed by the aforementioned feeding unit, The rotating body, when the conveying unit is properly mounted on the main body of the device, contacts the conveying roller to form a separation nip that separates the sheets one by one, together with the conveying roller. An image forming system according to any one of configurations 20 to 22, characterized by the above. (Composition 24) The time during which the transport unit is properly mounted on the main body of the device is longer than the predetermined threshold. An image forming system according to any one of configurations 20 to 23, characterized by the above. [Explanation of Symbols]

[0082] 11: Feeding unit (pickup roller) / 12: Conveying roller / 13: Rotating body (separation roller) / 13a: Torque limiter / 20: Conveying unit (separation roller unit) / 90a: Sheet detection unit (conveying sensor) / 91: Drive source (feeding motor) / 100: Image forming apparatus / 102, 202: Notification unit (operation display unit) / 110: Control unit (engine control unit) / 120: Main unit / 300: Server / 310: Control unit (calculation unit) / 400: Information processing unit (maintenance management computer) / 402: Notification unit (display unit) / 500: Image forming system / N: Separation nip / TH1, TH2: Threshold / X, Y: Interval

Claims

1. In an image forming apparatus, The main body of the device, A conveying unit detachably attached to the main body of the device, the conveying unit having a rotating body for conveying sheets, A drive source that generates a driving force for driving the rotating body, A notification unit capable of notifying information that the transport unit is not properly attached to the main body of the device, The system comprises a control unit that controls the drive source and the notification unit, The control unit acquires the load of the drive source corresponding to each of the multiple sheets being transported, and controls the notification unit to notify the information if a sheet jams while being transported in a section where the load of the drive source is less than a predetermined threshold. An image forming apparatus characterized by the following:

2. A feeding unit that feeds the sheets, The system further comprises a conveying roller for conveying the sheet fed by the aforementioned feeding unit, The rotating body, when the conveying unit is properly mounted on the main body of the device, contacts the conveying roller to form a separation nip that separates the sheets one by one, together with the conveying roller. The image forming apparatus according to feature 1.

3. The load on the drive source is a value based on the integrated value of the PWM signal used to control the drive source from the start of sheet feeding by the feeding unit until a predetermined time. The image forming apparatus according to feature 2.

4. The transport unit includes a torque limiter that is driven and connected to the rotating body. The image forming apparatus according to feature 2.

5. When the transport unit is properly mounted on the main body of the device, the load on the drive source is greater than the predetermined threshold. The image forming apparatus according to any one of claims 1 to 4.

6. The control unit has multiple printing modes, The predetermined threshold is changed according to the plurality of print modes. The image forming apparatus according to any one of claims 1 to 4.

7. The predetermined threshold is changed according to the attributes of the sheet being transported. The image forming apparatus according to any one of claims 1 to 4.

8. In an image forming apparatus, The main body of the device, A conveying unit detachably attached to the main body of the device, the conveying unit having a rotating body for conveying sheets, A sheet detection unit that detects the sheet, A notification unit capable of notifying information that the transport unit is not properly attached to the main body of the device, The system includes a control unit that controls the notification unit, The control unit acquires the time from when each of the multiple sheets being transported is fed until it reaches the sheet detection unit, and controls the notification unit to notify the information if a sheet being transported in a section where the time is shorter than a predetermined threshold is jammed. An image forming apparatus characterized by the following:

9. A feeding unit that feeds the sheets, The system further comprises a conveying roller for conveying the sheet fed by the aforementioned feeding unit, The rotating body, when the conveying unit is properly mounted on the main body of the device, contacts the conveying roller to form a separation nip that separates the sheets one by one, together with the conveying roller. The image forming apparatus according to feature 8.

10. The time during which the transport unit is properly mounted on the main body of the device is longer than the predetermined threshold. The image forming apparatus according to feature 8.

11. The control unit has multiple printing modes, The predetermined threshold is changed according to the plurality of print modes. The image forming apparatus according to any one of claims 8 to 10.

12. The predetermined threshold is changed according to the attributes of the sheet being transported. The image forming apparatus according to any one of claims 8 to 10.

13. In an image forming system comprising an image forming apparatus and a server capable of communicating with the image forming apparatus via a network, The image forming apparatus is The main body of the device, A conveying unit detachably attached to the main body of the device, the conveying unit having a rotating body for conveying sheets, It comprises a drive source that generates a driving force for driving the rotating body, A notification unit capable of notifying information that the transport unit is not properly attached to the main body of the device, The system comprises a control unit provided in either the image forming apparatus or the server, The control unit acquires the load of the drive source corresponding to each of the plurality of sheets transported to the image forming apparatus, and outputs a signal to operate the notification unit to notify the information if a sheet jams while being transported in a section where the load of the drive source is less than a predetermined threshold. An image forming system characterized by the following features.

14. The server is further equipped with an information processing device that can communicate via a network, The notification unit is provided in at least one of the image forming apparatus and the information processing apparatus. The image forming system according to claim 13, characterized in that it is as described above.

15. The control unit is provided in the server, The image forming system according to claim 13, characterized in that it is as described above.

16. The image forming apparatus includes a feeding unit for feeding sheets and a conveying roller for transporting the sheets fed by the feeding unit. The rotating body, when the conveying unit is properly mounted on the main body of the device, contacts the conveying roller to form a separation nip that separates the sheets one by one, together with the conveying roller. The image forming system according to claim 13, characterized in that it is as described above.

17. The load on the drive source is a value based on the integrated value of the PWM signal used to control the drive source from the start of sheet feeding by the feeding unit until a predetermined time. The image forming system according to claim 16.

18. The transport unit includes a torque limiter that is driven and connected to the rotating body. The image forming system according to claim 16.

19. When the transport unit is properly mounted on the main body of the device, the load on the drive source is greater than the predetermined threshold. The image forming system according to any one of claims 13 to 18.

20. In an image forming system comprising an image forming apparatus and a server capable of communicating with the image forming apparatus via a network, The image forming apparatus is The main body of the device, A conveying unit detachably attached to the main body of the device, the conveying unit having a rotating body for conveying sheets, It has a sheet detection unit that detects the sheet, A notification unit capable of notifying information that the transport unit is not properly attached to the main body of the device, The system comprises a control unit provided in either the image forming apparatus or the server, The control unit acquires the time from when each of the multiple sheets being transported is fed until it reaches the sheet detection unit, and outputs a signal to operate the notification unit to notify the information if a sheet being transported jams in a section where the time is shorter than a predetermined threshold. An image forming system characterized by the following features.

21. The server is further equipped with an information processing device that can communicate via a network, The notification unit is provided in at least one of the image forming apparatus and the information processing apparatus. The image forming system according to claim 20, characterized in that it is as described above.

22. The control unit is provided in the server, The image forming system according to claim 20, characterized in that it is as described above.

23. A feeding unit that feeds the sheets, The system further comprises a conveying roller for conveying the sheet fed by the aforementioned feeding unit, The rotating body, when the conveying unit is properly mounted on the main body of the device, contacts the conveying roller to form a separation nip that separates the sheets one by one, together with the conveying roller. The image forming system according to any one of claims 20 to 22, characterized in that it is the same as described in the previous claim.

24. The time during which the transport unit is properly mounted on the main body of the device is longer than the predetermined threshold. The image forming system according to any one of claims 20 to 22, characterized in that it is the same as described in the previous claim.

Images