JP2015003773A - Image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation apparatus which can measure a paper feed state of recording paper in real time and control an optimal delivery operation in accordance with the paper feed state.SOLUTION: An image formation apparatus includes a delivery roller 81 which delivers recording paper P2 stored in a paper feed tray 4 to a transportation path R1 from the top layer and a paper feed state detection part 85 which measures the delivery state of the recording paper P2 from the paper feed tray 4 in a paper feeder 8. In the paper feeder 8, at the time of performing paper feed operation of the recording paper P2, the delivery operation of the recording paper P2 by the delivery roller 81 is controlled on the basis of the transportation state of the recording paper P2 detected by the paper feed state detection part 85.

Description

  The present invention relates to an image forming apparatus including a paper feeding device that feeds recording paper on which an image is formed, and more particularly to an image forming apparatus capable of detecting a conveyance state of a recording paper on a conveyance path.

  The image forming apparatus includes a paper feeding device having a paper feeding mechanism that feeds recording paper one by one from a paper feeding tray containing a plurality of recording papers, and records the recording paper fed one by one from the paper feeding device. On the other hand, an image is formed. A sheet feeding device in such an image forming apparatus includes a feeding roller as a sheet feeding mechanism for feeding a plurality of recording sheets stored in a sheet feeding tray from an upper layer portion. In the image forming apparatus, the recording paper fed one by one by the feeding roller is sent out to a conveyance path for image formation by a pair of rollers on the downstream side.

  By the way, in an image forming apparatus provided with such a sheet feeding device, a sheet feeding abnormality occurs due to a paper slip or the like in a recording sheet feeding operation by a roller. In order to determine whether or not the recording paper feeding operation from the paper feeding device is normally performed, the conventional image forming apparatus detects that the fed recording paper has reached a predetermined position. A paper feed sensor or the like is provided (see Patent Document 1). In such an image forming apparatus equipped with a sheet feeding device as described above, an abnormal recording sheet feeding has been determined by being installed on the downstream side of the feeding roller.

  In recent years, it has been proposed to use a two-dimensional movement amount detection sensor using an image sensor based on the same method as an optical mouse as a conveyance state detection unit for measuring the conveyance state of a recording paper ( Patent Document 2). In the image forming apparatus of Patent Document 2, a conveyance state detection unit by a two-dimensional movement amount detection sensor is arranged on a paper feed tray on the upstream side of the feeding roller along the recording paper conveyance direction. As a result, the moving amount and moving speed of the recording paper fed from the paper feed tray by the feed roller are measured, and a failure or deterioration state of the paper feed mechanism is determined.

JP 2002-128323 A JP 2005-041623 A

  By the way, in the case of the paper feed sensor or the like in Patent Document 1, since it is arranged downstream of the feeding roller, it is possible to determine whether or not the paper feed operation is abnormal, but it is impossible to detect the recording paper feed status. For this reason, when it is determined that an abnormality has occurred in the paper feeding operation, depending on the paper feeding status of the recording paper, the recording paper can be fed normally by optimally controlling the feeding roller. Even if there is, it is common to notify the outside of the occurrence of an abnormality. In addition, even if the feeding roller is re-driven in the event of an abnormality and the paper feeding operation is retried, the feeding state of the recording paper that causes the feeding error is caused by the re-driving of the feeding roller. It could get worse.

  Further, in the image forming apparatus of Patent Document 2, a two-dimensional movement amount detection sensor capable of measuring the behavior of the recording paper is arranged upstream of the feeding roller, but the occurrence of abnormality in the recording paper conveyance state is confirmed. To do. Therefore, compared with the image forming apparatus that performs the abnormality determination of the paper feeding operation by the above-described paper feeding sensor, the accuracy in the abnormality determination is increased, but the feeding roller is optimally driven and the paper feeding operation is retried. is not. Therefore, depending on the paper feeding status, even though the paper can be fed normally by optimally controlling the rotation operation of the feeding roller, it is notified to the outside as an abnormality determination.

  In view of such a problem, an object of the present invention is to provide an image forming apparatus capable of measuring a sheet feeding state of a recording sheet in real time and controlling an optimum feeding operation according to the sheet feeding state.

  In order to achieve the above object, an image forming apparatus of the present invention includes a paper feed tray that stores recording paper, an image forming unit that forms an image on the recording paper, and transports the recording paper to the image forming unit. An image forming apparatus comprising: a conveyance path; and a feeding roller that feeds the recording paper from the paper feed tray to the conveyance path, wherein the image forming apparatus is upstream of the feeding roller along a conveyance direction of the recording paper. A paper feed state detection unit for measuring a conveyance state of the recording paper stored in the paper feed tray, and a paper feed for receiving a measurement result from the paper feed state detection unit and controlling a driving operation of the feeding roller A control unit, and the sheet feeding control unit detects the sheet feeding state detection unit after driving the feeding roller and starting the sheet feeding operation of the recording sheet from the sheet feeding tray. Above When receiving the displacement information indicating a transfer state in the paper feed tray Rokushi, and sets on the basis of the feed displacement information driving state rollers.

  In this image forming apparatus, the displacement information from the paper feed state detection unit is a movement amount of the recording paper after a predetermined time has elapsed from the start of paper feed, and the paper feed control unit is configured to supply the paper feed state detection unit. When the movement amount of the recording paper received from the printer is small, a retry operation by the feeding roller may be performed.

  In the image forming apparatus, the paper feed control unit determines that the recording paper is normally fed when the movement amount of the recording paper is larger than a first reference value. At this time, when the movement amount of the recording paper is not more than the first reference value and the movement amount is not less than the second reference value smaller than the first reference value, the sheet feeding control unit is configured to move the feeding roller. The first retry operation for extending the feeding of the recording paper by the first retry operation is executed, and the amount of movement of the recording paper from the paper feed state detection unit is received again after the extension time by the first retry operation elapses. Thus, it may be determined whether or not the recording paper is fed normally.

  Further, the paper feed control unit is configured so that when the movement amount of the recording paper is equal to or smaller than the first reference value and the movement amount is smaller than the second reference value smaller than the first reference value, the feeding roller performs the A second retry operation for re-driving the feeding roller after temporarily stopping the feeding of the recording paper is executed, and again after the elapse of a predetermined time from the start of the second retry operation, the paper feed state detection unit It is also possible to determine whether or not the recording paper is fed normally by receiving the amount of movement of the recording paper.

  In the image forming apparatus of the present invention, the displacement information from the paper feed state detection unit is a moving speed of the recording paper after a predetermined time has elapsed from the start of paper feed, and the paper feed control unit is configured to feed the paper feed state. When the moving speed of the recording paper received from the detection unit is low, a retry operation by the feeding roller may be performed.

  At this time, the paper feed control unit may extend the feeding of the recording paper by the feeding roller when performing the retry operation by the feeding roller. Further, when the paper feeding control unit performs a retry operation by the feeding roller, the feeding roller may be driven again after temporarily stopping feeding of the recording paper by the feeding roller.

  In each of the image forming apparatuses, the sheet feeding control unit integrates the driving time of the feeding roller, and determines whether to perform a retry operation by the feeding roller based on the driving time of the feeding roller. May be set.

  In each of the image forming apparatuses described above, a criterion for determining whether or not to perform a retry operation by the feeding roller may be set based on the type of the recording paper.

  In each of the image forming apparatuses described above, the paper feed control unit sets a rotation speed of the feed roller based on displacement information from the paper feed state detection unit when performing a retry operation by the feed roller. It does not matter.

  In each of the image forming apparatuses described above, when the paper feeding control unit performs a retry operation by the feeding roller, the timing of image formation in the image forming unit may be delayed by a time necessary for the retry operation. I do not care.

  In each of the image forming apparatuses described above, when the number of times the retry operation has been performed by the feeding roller exceeds a predetermined number, the sheet feeding control unit has an abnormality in the feeding operation of the recording paper by the feeding roller. It does not matter if it is determined that

  In each of the image forming apparatuses described above, the feeding control unit rotates the feeding roller after a predetermined time has passed since the feeding state detection unit has notified that the movement of the recording paper is no longer detected. It does not matter as a thing to stop.

  In each of the image forming apparatuses described above, the paper feed state detection unit includes a light source that irradiates light to the recording paper and an image sensor that receives reflected light of the recording paper based on light from the light source.

  According to the present invention, the recording paper fed by the feed roller is detected in the paper feed tray on the upstream side of the feed roller, and the feed roller is controlled based on the detection result. The feeding roller can be controlled in real time according to the paper feeding status. Therefore, there is only a delay in the feeding of the recording paper by the feeding roller, and the feeding operation can be continued only by extending the driving time of the feeding roller. Therefore, it is not necessary to stop the paper feeding operation. Further, when the recording paper is fed by the feeding roller, the frictional force between the feeding roller and the recording paper is weak, and it can be determined whether or not the paper is slipping. If this paper slip has occurred, the feeding roller can be stopped and then re-driven to continue the paper feeding operation. There is no need to stop the operation. Therefore, since the feeding roller can be controlled in an optimal driving state in real time, the efficiency in the paper feeding operation can be improved without wastefully determining a paper feeding abnormality.

FIG. 2 is an external perspective view of the image forming apparatus of the present invention. FIG. 2 is a schematic configuration diagram illustrating an internal configuration of the image forming apparatus illustrated in FIG. 1. FIG. 2 is an enlarged view showing a part of a sheet feeding device in the image forming apparatus shown in FIG. 1. FIG. 2 is a block diagram illustrating a configuration of a control unit of the image forming apparatus illustrated in FIG. 1. FIG. 5 is a flowchart showing a control operation in a printing operation by the image forming apparatus shown in FIG. 1. FIG. 6 is a flowchart showing a sheet feeding control operation in the printing operation according to the flowchart of FIG. 5. FIG. 7 is a flowchart showing an abnormality determination control operation in the paper feed control operation according to the flowchart of FIG. 6. These are graphs showing the relationship between the recording paper feed state from the paper feed tray and the reference value for abnormality determination. FIG. 7 is a flowchart showing a retry control operation in the paper feed control operation according to the flowchart of FIG. 6. These are the flowcharts which show the paper feed stop control operation in the paper feed control operation according to the flowchart of FIG. These are the flowcharts which show the abnormality determination control operation in the other example 1 of the paper feed control operation. These are the flowcharts which show the retry control operation in the another example 2 of the paper feed control operation. These are the flowcharts which show the abnormality determination control operation in the another example 3 of the paper feed control operation. These are the flowcharts which show the abnormality determination control operation in the another example 4 of the paper feed control operation.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, when using terms indicating a specific direction or position (for example, “left / right”, “up / down”, etc.) as necessary, the direction orthogonal to the paper surface in FIG. I have to. These terms are used for convenience of explanation, and do not limit the technical scope of the present invention.

<Configuration of image forming apparatus>
First, the overall configuration of an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an external perspective view of an image forming apparatus according to the present invention, and FIG. 2 is a schematic diagram illustrating an internal configuration of the image forming apparatus.

  As shown in FIGS. 1 and 2, the image forming apparatus 1 includes an image reading unit 3 that reads an image from a document P 1, a paper feed tray 4 that stores recording paper P 2 on which an image is formed, and a paper feed tray 4. A transfer unit 5 that transfers the toner image to the fed recording paper P2, a fixing unit 6 that fixes the toner image transferred by the transfer unit 5 to the recording paper P2, and a fixing unit 6 that fixes the image to form an image. A paper discharge tray 7 on which the recording paper P2 is discharged, and an operation panel 9 for receiving operations on the image forming apparatus 1. In the image forming apparatus 1, an image reading unit 3 is provided on the upper part of the apparatus main body 2, and a transfer unit 5 is provided below the image reading unit 3.

  A paper discharge tray 7 is provided on the upper side of the transfer unit 5 in the apparatus main body 2 to receive the recording paper P2 that has been image-recorded and discharged by the transfer unit 5 and the fixing unit 6, and the paper feed tray 4 However, it is configured to be insertable / removable below the transfer portion 5 in the apparatus main body 2. With such a configuration, as will be described later, the recording paper P2 stored in the paper feed tray 4 is fed into the apparatus main body 2 and then transported upward, whereby the upper portion of the paper feed tray 4 is After the image is transferred by the transfer unit 5 disposed in the image and fixed by the fixing unit 6, the image is discharged onto a discharge tray 7 provided in a space (a recessed space) between the image reading unit 3 and the transfer unit 5. Is done.

  The image reading unit 3 provided on the upper part of the apparatus main body 2 includes a scanner unit 31 that reads an image from the document P1, and an automatic document conveyance unit that is provided on the scanner unit 31 and conveys the document P1 to the scanner unit 31 one by one. (ADF: Auto Document Feeder) 32. An operation panel 9 is provided on the front side (front side) of the apparatus main body 2. Then, the user performs a key operation while looking at the display screen of the operation panel 9 to perform a setting operation for a function selected from the various functions of the image forming apparatus 1 or execute an operation on the image forming apparatus 1. Can be instructed.

  Next, the internal structure of the apparatus main body 2 will be described with reference to FIG. Of the image reading unit 3 in the upper part of the apparatus main body 2, the scanner unit 31 includes a document table 33 having a platen glass (not shown) on the upper surface side, a light source unit 34 that emits light to the document P1, and a document P1. The image sensor 35 that photoelectrically converts the reflected light from the image into image data, the imaging lens 36 that forms an image of the reflected light on the image sensor 35, and the reflected light from the original P1 are sequentially reflected and incident on the imaging lens 36. And a mirror group 37 to be operated. The light source unit 34, the image sensor 35, the imaging lens 36, and the mirror group 37 are provided inside the document table 33, and the light source unit 34 and the mirror group 37 are configured to be movable in the left-right direction with respect to the document table 33. .

  An ADF 32 is provided on the upper surface side of the scanner unit 31 so as to be openable and closable with respect to the document table 33. The ADF 32 also has a function of bringing the document P1 into close contact with the platen glass (not shown) by covering the document P1 on the platen glass (not shown) of the document table 33. The ADF 32 includes a document placement tray 38 and a document discharge tray 39.

  When the image reading unit 3 having such a configuration reads a document P1 on a platen glass (not shown) of the document table 33, light is irradiated to the document P1 from the light source unit 34 that moves in the right direction (sub-scanning direction). Is done. The reflected light reflected from the document P1 is sequentially reflected by a mirror group 37 that moves in the right direction as in the light source unit 34, enters the imaging lens 36, and forms an image on the image sensor 35. The image sensor 35 performs photoelectric conversion for each pixel according to the intensity of incident light, and generates an image signal (RGB signal) corresponding to the image of the document P1.

  On the other hand, when reading the document P1 placed on the document placement tray 38, the document P1 is transported to the reading position by the document transport mechanism 40 including a plurality of rollers or the like. At this time, the light source unit 34 and the mirror group 37 of the scanner unit 31 are fixed at predetermined positions inside the document table 33. Therefore, the light source unit 34 irradiates the reading position portion of the document P1 with light, and the reflected light is imaged on the image sensor 35 via the mirror group 37 and the imaging lens 36 of the scanner unit 31. Then, the image sensor 35 converts the image signal (RGB signal) corresponding to the image of the document P1. Thereafter, the document P1 is discharged to the document discharge tray 39.

  The transfer unit 5 that transfers the toner image to the recording paper P2 includes an image forming unit 51 that generates toner images of Y (Yellow), M (Magenta), C (Cyan), and K (Key tone) colors, and an image forming unit. 51, an intermediate transfer belt 53 to which a toner image of each color is transferred from the image forming unit 51 by contacting an exposure unit 52 provided below each of the image forming units 51, an image forming unit 51 of each color arranged in the horizontal direction, and an image forming unit. A primary transfer roller 54 provided at a position facing the upper side with respect to each image forming unit 51 of each color so as to sandwich the unit 51 and the intermediate transfer belt 53, a drive roller 55 for rotating the intermediate transfer belt 53, and A driven roller 56 that rotates when the rotation of the driving roller 55 is transmitted through the intermediate transfer belt 53, a secondary transfer roller 57 that is installed at a position facing the driving roller 55 across the intermediate transfer belt 53, and intermediate transfer And a cleaner unit 58 which is installed in a position facing the driven roller 56 across the belt 53, provided.

  The image forming unit 51 includes a photosensitive drum 61 that is in contact with the outer circumferential surface of the intermediate transfer belt 53, a charger 62 that charges the outer circumferential surface of the photosensitive drum 61 by corona discharge, and a toner that is charged by stirring. A developing unit 63 that adheres to the outer peripheral surface of the drum 61 and a cleaner unit 64 that removes toner remaining on the outer peripheral surface of the photosensitive drum 61 after the toner image is transferred to the intermediate transfer belt 53 are provided. At this time, the photosensitive drum 61 is installed at a position facing the primary transfer roller 54 with the intermediate transfer belt 53 interposed therebetween, and rotates in the clockwise direction in FIG. Around the photosensitive drum 61, a primary transfer roller 54, a cleaner unit 64, a charger 62, and a developing device 63 are sequentially arranged along the rotation direction of the photosensitive drum 61.

  Further, the intermediate transfer belt 53 is composed of an endless belt member having conductivity, for example, and is wound around the drive roller 55 and the driven roller 56 without loosening, so that the intermediate transfer belt 53 is rotated according to the rotation of the drive roller 55 as shown in FIG. In the counterclockwise direction. Around the intermediate transfer belt 53, the secondary transfer roller 57, the cleaner unit 58, and the image forming units 51 for each color of YMCK are arranged in order along the rotation direction of the intermediate transfer belt 53.

  Further, the fixing unit 6 that fixes the toner image transferred to the recording paper P2 includes a heating roller 59 including a halogen lamp that heats the recording paper P2 to fix the toner image on the recording paper P2, and the heating roller 59. And a pressurizing roller 60 that presses the recording paper P2 while sandwiching it. The heating roller 59 may be one in which the surface of the heating roller 51 is heated by generating an eddy current on the surface by electromagnetic induction.

  As shown in FIG. 3, the paper feeding device 8 having a plurality of paper feeding trays 4 includes a feeding roller 81 that feeds the recording paper P2 stored in the paper feeding tray 4 from the uppermost layer to the conveying path R1, and a paper feeding path R1. A pair of vertical transport rollers 84 for vertically transporting the recording paper P2 fed to the main transport path R0, a paper feed state detection unit 85 for measuring the feeding state of the recording paper P2 from the paper feed tray 4, A conveyance state detection unit 86 that is disposed on the downstream side of the conveyance roller pair 84 and measures the conveyance state of the recording paper P2 by the vertical conveyance roller pair 84. The main transport path R0 is the main path of the recording paper P2 that has undergone the image forming (printing) process. In addition, a paper feed path R1 is provided for each paper feed tray 4, and each paper feed path R1 joins the main transport path R0.

  The recording paper P2 in each paper feed tray 4 is sent to the paper feed path R1 one by one from the top layer by the rotational drive of the corresponding feed roller 81, and then the main transport path by the vertical transport roller pair 84. Sent to R0. The paper feed state detection unit 85 includes, for example, a light source 851 that irradiates light to the recording paper P2 and an image sensor 852 that receives reflected light from the recording paper P2, thereby moving and moving the recording paper P2. The speed is detected and output as recording paper displacement information. On the other hand, the conveyance state detection unit 86 is configured by a reflective sensor including a light emitting / receiving element, for example, so that the reflected light of the recording paper P2 based on the light from the light emitting element is received by the light receiving element and conveyed. The front and rear edges and the conveyance state of the paper P2 are detected.

  A manual feed tray 93 capable of feeding a predetermined size of recording paper P2 from the outside is provided on one side portion (right side portion in the embodiment) of the apparatus main body 2 in the left-right direction. The manual feed tray 93 is supplementarily provided separately from the normal paper feed tray 4 in the apparatus main body 2, and is attached to the left and right sides of the apparatus main body 2 so as to be openable and closable. ing. The recording paper P2 on the manual feed tray 93 is sent one by one from the uppermost layer toward the main transport path R0 via the manual feed path R2 by rotation driving of a feed roller or the like.

  Further, a timing roller pair 87 is provided in the main transport path R0 as a transport roller pair for transporting the recording paper P2 transported from the paper feeding device 8 to the transfer unit 5. The timing roller pair 87 transfers the recording paper P2 from the paper supply device 8 in synchronization with the toner image formation timing in the transfer unit 5 in order to transfer the toner image to the recording paper P2 normally in the transfer unit 5. It conveys to the part 5. A recording paper detection unit 88 that detects the leading edge of the recording paper P2 is provided below the timing roller pair 87 (upstream in the transport direction). Accordingly, when the leading edge of the recording paper P2 is detected by the recording paper detection unit 88, the recording paper P2 conveyed from the paper feeding device 8 is temporarily transferred by the timing roller pair 87 until the recording paper P2 is conveyed at the transfer timing in the transfer unit 5. Stop. Note that the recording paper detection unit 88 is configured by a reflective sensor, for example, like the conveyance state detection unit 86, and detects the leading edge of the recording paper P2 conveyed from the paper supply device 8.

  Further, a paper discharge roller pair 91 for discharging the printed recording paper P2 is disposed at the terminal portion at the most downstream side of the main transport path R0. The printed recording paper P <b> 2 is discharged to the paper discharge tray 7 by the rotational drive of the paper discharge roller pair 91. In the main transport path R0, a recording paper detection unit 90 that detects the trailing edge of the recording paper P2 is disposed below the paper discharge roller pair 91 (upstream in the transport direction). Therefore, by detecting the trailing edge of the recording paper P2 by the recording paper detection unit 90, it can be confirmed that the recording paper P2 has been normally discharged from the paper discharge roller pair 91 to the paper discharge tray 7. Note that the recording paper detection unit 90 is configured by a reflective sensor, for example, similarly to the conveyance state detection unit 88, and detects the trailing edge of the recording paper P2 conveyed from the fixing unit 6.

  The image forming apparatus 1 includes a control unit 10 having the configuration shown in FIG. 4. The control unit 10 controls each part of the image forming apparatus 1 to perform printing operation on the recording paper P2 and image reading from the document P1. Various operations such as operations are performed. The control unit 10 includes a CPU (Central Processing Unit) 101 that executes various arithmetic processes and controls, a ROM (Read Only Memory) 102 that stores control programs, and a RAM (Random Access) that temporarily stores arithmetic data. Memory) 103, an image processing unit 104 that generates image data that is a basis of the toner image formed by the transfer unit 5, an image memory 105 that temporarily stores the image data obtained by the image processing unit 104, and an image And an input / output interface 106 that transmits and receives signals to and from each unit constituting the forming apparatus 1.

  When the control unit 10 configured as described above receives a signal corresponding to the operation received by the operation panel 9, the CPU 101 recognizes an operation based on the operation received by the operation panel 9. Similarly, when the control unit 10 receives a signal transmitted from an external terminal or the like via a communication network 110 such as a LAN (Local Area Network) by the input / output interface 106, the control unit 10 recognizes an operation designated by the external terminal. . Thereby, the CPU 101 reads a control program based on an operation designated via the operation panel 9 or the external terminal from the ROM 102, and the CPU 101 operates based on the control program.

  At this time, based on the control program read from the ROM 102, the CPU 101 controls the image reading unit 3, the exposure unit 52, the transfer unit 5, the fixing unit 6, and the paper feeding device 8. Signals are output to the control unit 114, the transfer control unit 115, the fixing control unit 116, and the paper feed control unit 118, respectively. Accordingly, the image forming apparatus 1 responds to a specified operation by giving signals from the control unit 10 to the image reading control unit 113, the transfer control unit 115, the fixing control unit 116, and the paper feed control unit 118. Thus, each of the image reading unit 3, the exposure unit 52, the transfer unit 5, the fixing unit 6, and the paper feeding device 8 is driven.

<Printing action>
Next, the printing operation by the image forming apparatus 1 will be described below. When the image forming apparatus 1 receives an instruction to perform a printing operation from the operation panel 9 or an external terminal, in the control unit 10, the CPU 101 reads a control program for the printing operation from the ROM 102, and performs the printing operation. Start control action. That is, according to the flowchart of FIG. 5, the CPU 101 first controls the paper feed control unit 118 to operate the paper feed device 8 (STEP 101). As a result, the paper feed device 8 drives the feed roller 81 to feed the uppermost recording paper P2 from the paper feed tray 4 and send it to the transport path R1. The recording paper P2 fed from the paper feed tray 4 to the transport path R1 is sent out from the main transport path R0 to the vertical transport path R1 by the vertical transport roller pair 84.

  Further, the CPU 101 drives and controls the exposure control unit 114 and the transfer control unit 115 so as to transfer the toner image to the recording paper P2 sent to the main transport path R1 (STEP 102). At this time, the CPU 101 supplies the image processing unit 103 with the image signal read from the original P1 by the image reading unit 3 through the image reading control unit 113 or the image signal received from the external terminal through the input / output interface 106.

  As a result, the image processing unit 103 generates image data for forming toner images of Y, M, C, and K colors based on the given image signal, and stores the image data in the image memory 105. Image data of each color Y, M, C, and K stored in the image memory 105 is read from the CPU 101 and given to the exposure control unit 114. Accordingly, the exposure control unit 114 drives the light emitting elements (not shown) in the exposure unit 52 based on the image data of each color of Y, M, C, and K, so that each of the Y, M, C, and K colors is exposed. An electrostatic latent image is formed on the body drum 61. That is, since the transfer control unit 115 drives the transfer unit 5, the laser beam from the exposure unit 52 is applied to the surface of the photosensitive drum 61 charged by the charger 62 in the image forming unit 51 of each color of Y, M, C, and K. , And an electrostatic latent image corresponding to each of the Y, M, C, and K images is formed.

  The toner charged by the developing device 63 is transferred to the surface of the photosensitive drum 61 on which the electrostatic latent image is formed, and a toner image is formed on the photosensitive drum 61 serving as the first image carrier. Since the toner image carried on the surface of the photosensitive drum 61 is transferred to the intermediate transfer belt 53 by the electrostatic force of the primary transfer roller 54 when coming into contact with the intermediate transfer belt 53, the second image carrier. A toner image in which the colors Y, M, C, and K are overlapped is formed on the surface of the intermediate transfer belt 53. On the other hand, the untransferred toner remaining on the photosensitive drum 61 having the toner image transferred to the intermediate transfer belt 53 is scraped off by the cleaner unit 64 and removed from the photosensitive drum 61.

  Further, when the leading end of the recording paper P2 transported to the main transport path R0 is detected by the recording paper detection unit 88, the detection result is given to the transfer control unit 115. The transfer control unit 115 recognizes that it has reached. The transfer control unit 115 operates the timing roller pair 87 in accordance with the timing at which the toner image is transferred to the intermediate transfer belt 53. At this time, the toner image transferred to the intermediate transfer belt 53 is moved to the transfer position where the intermediate transfer belt 53 contacts the secondary transfer roller 57 by the rotation of the intermediate transfer belt 53 by the driving roller 55 and the driven roller 56, and the main conveyance path. It is transferred to the recording paper P2 conveyed to the transfer position on R0. Untransferred toner remaining on the intermediate transfer belt 53 that has transferred the toner image onto the recording paper P <b> 2 is scraped off by the cleaner unit 58 and removed from the intermediate transfer belt 53.

  Then, the recording paper P <b> 2 on which the toner image is transferred at the contact position with the secondary transfer roller 57 is conveyed to the fixing unit 6 by the heating roller 59 and the pressure roller 60. At this time, the CPU 101 drives and controls the fixing control unit 116 to fix the toner image on the recording paper P2 conveyed to the fixing unit 6 (STEP 103). That is, the fixing controller 116 controls the rotation operation of the heating roller 59 and the pressure roller 60 and simultaneously controls the heating operation of the heating roller 59.

  Thus, when the recording paper P2 on which the unfixed toner image is placed passes through the fixing nip portion of the fixing unit 6, the recording paper P2 is heated by the heating roller 59 and pressed by the pressure roller 60, so that the unfixed toner image is obtained. Is fixed on the paper. Then, after the toner image is fixed (after single-sided printing), the recording paper P <b> 2 is discharged to the paper discharge tray 7 by the paper discharge roller pair 91 when it is conveyed to the paper discharge roller pair 91. At this time, the recording paper detection unit 90 detects the trailing edge of the recording paper P 2, and the detection result is given to the control unit 10. Accordingly, the control unit 10 confirms that the recording paper P2 has been normally discharged to the paper discharge tray 7.

<Paper feed control operation>
A control operation (paper feeding control operation) for the paper feeding device 8 in the above-described printing operation will be described below. When the control unit 10 performs the control operation for the printing operation according to the flowchart of FIG. 5, as described above, first, the sheet feeding control unit 118 is controlled to start the sheet feeding operation by the sheet feeding device 8. (STEP 101). When the paper feed control operation in STEP 101 is started, the paper feed controller 118 first drives the feed roller 81 to feed the recording paper P2 from the paper feed tray 4 as shown in the flowchart of FIG. 6 (STEP 201). . As a result, the feeding roller 81 rotates, and the uppermost recording paper P2 in the paper feed tray 4 is pulled out and sent out to the transport path R1.

  In this way, when the recording paper P2 is being delivered by the delivery roller 81, the paper feed control unit 118 performs an abnormality determination control operation in order to determine whether or not the recording paper P2 is conveyed abnormally (STEP 202). ). When the sheet feeding control unit 118 shifts to the abnormality determination control operation, as shown in the flowchart of FIG. 7, whether or not the determination timing is reached depending on whether or not a predetermined time T has elapsed from the start of rotation of the feeding roller 81. (STEP 301). At this time, when the determination timing is reached after the predetermined time T has elapsed (YES in STEP 301), the paper feed control unit 118 uses the feed roller 81 to detect the displacement information of the recording paper P2 fed from the paper feed tray 4 as a paper feed state detection unit. 85 (STEP 302).

  The paper feed state detection unit 85 operates the light source 851 and the image sensor 852 so that the image sensor 852 receives reflected light from the recording paper P2 based on the light emitted from the light source 851 at every predetermined timing. As a result, the paper feed state detection unit 85 acquires the image data of the recording paper P2 that passes through the imaging region of the image sensor 852 at every predetermined timing. The paper feed state detection unit 85 performs pattern matching processing or the like on the image data at each timing, and the amount of movement M of the recording paper P2 from the start of paper feed is transferred to the paper feed control unit 118 as displacement information. Output.

  Upon receiving the displacement information from the paper feed state detection unit 85, the paper feed control unit 118 compares the movement amount M of the recording paper P2 based on this displacement information with the first reference value M1 (STEP 303). At this time, if the movement amount M of the recording paper P2 is less than the first reference value M1 (Yes in STEP303), the paper feed control unit 118 reattempts the paper feed operation based on the retry control operation (STEP 203) described later. It is confirmed whether or not the number of times N (hereinafter referred to as “retry number N”) exceeds a predetermined number N1 (STEP 304). When the retry count N is equal to or less than the predetermined count N1 (YES in STEP 304), the paper feed control unit 118 sets the movement amount M of the recording paper P2 based on the displacement information received in STEP 302 to the second reference value M2 (M2). Compare with <M1) (STEP 305).

  In order to confirm the movement state of the recording paper P2, the relationship between the predetermined time T and the first and second reference values M1 and M2 will be described below with reference to the graph of FIG. In the graph of FIG. 8, the solid line represents the temporal transition of the movement amount of the recording paper P2 when the paper feeding operation is normally performed, and the broken line represents the movement amount of the recording paper P2 when the paper feed start is delayed. The one-dot chain line represents the time transition of the moving amount of the recording paper P2 when the paper slide of the feeding roller 81 occurs. As shown in FIG. 8, when the paper feed operation is normally performed when the predetermined time T has elapsed, the moving amount of the recording paper P2 exceeds the first reference value M1, but the recording paper by the feeding roller 81 When the feeding failure of P2 occurs, the moving amount of the recording paper P2 is less than the first reference value M1.

  In addition, when the feeding failure of the recording paper P2 by the feeding roller 81 occurs, and the paper slip by the feeding roller 81 occurs, the feeding speed of the recording paper P2 becomes slower than normal. Therefore, when the paper slip is generated by the feeding roller 81, the movement amount of the recording paper P2 falls below the second reference value M2 which is smaller than the first reference value M1 when the predetermined time T has elapsed. On the other hand, even when the feeding failure of the recording paper P2 by the feeding roller 81 occurs, if the feeding speed of the recording paper P2 is not different from the normal time only due to a delay in the feeding of the recording paper P2, it is predetermined. When the time T has elapsed, the moving amount of the recording paper P2 exceeds the second reference value M2.

  Note that the predetermined time T for determining the paper feed state is a time set for determining a moving amount that can confirm whether or not the occurrence of paper slippage by the feeding roller 81 is possible. For example, the recording paper P2 May be set based on the time required to reach the vertical conveying roller pair 84 in a normal state. At this time, the first reference value M1 is set to a value larger than the distance from the paper feed tray 4 to the vertical conveyance roller pair 84. The predetermined time T may be set according to the length of the photographing range of the image sensor 852 along the conveyance direction of the recording paper P2. At this time, the first reference value M1 is set to a value larger than the length of the shooting range of the image sensor 852.

  In STEP 305, when the paper feed control unit 118 confirms that the moving amount M of the recording paper P2 exceeds the second reference value M2 (Yes), recording by the feeding roller 81 is performed based on a first retry operation described later. In order to retry the paper feeding operation of the paper P2, the first retry flag F1 is set (STEP 306). That is, as in the case of the broken line in the graph of FIG. 8, when the feeding failure by the feeding roller 81 occurs but the subsequent feeding speed of the recording paper P2 does not change from the normal time, the process proceeds to STEP 306, and the first re-run. A trial flag F1 is set. Thereafter, the paper feed control unit 118 ends the abnormality determination control operation in STEP 202 (STEP 311).

  On the other hand, when the paper feed control unit 118 confirms that the moving amount M of the recording paper P2 is equal to or smaller than the second reference value M2 (including that the moving amount M is 0) (NO in STEP 305), a later-described first Based on the 2 retry operation, the second retry flag F2 is set to retry the operation of feeding the recording paper P2 by the feeding roller 81 (STEP307). That is, as in the case of the alternate long and short dash line in the graph of FIG. 8, when a feeding failure by the feeding roller 81 occurs and the feeding speed of the recording paper P2 becomes slow due to paper slipping or the like thereafter, the process proceeds to STEP307. Thus, the second retry flag F2 is set. Thereafter, the paper feed control unit 118 ends the abnormality determination control operation in STEP 202 (STEP 311).

  In STEP 303, when the paper feed control unit 118 confirms that the moving amount M of the recording paper P2 is equal to or greater than the first reference value M1 (Yes), an end flag F3 indicating that the conveyance abnormality determination is finished is set ( (STEP308). That is, as in the case of the solid line in the graph of FIG. 8, when the feeding by the feeding roller 81 operates normally, the process proceeds to STEP 308 and the end flag F3 is set. Thereafter, the paper feed control unit 118 ends the abnormality determination control operation in STEP 202 (STEP 311).

  Further, in STEP 304, when the paper feed control unit 118 confirms that the number of retries N exceeds the predetermined number N1 (No in STEP 304), the paper feed operation of the recording paper P2 in the paper feeder 8 has failed. Determination is made, and an error flag F4 indicating the occurrence of an abnormality is set (STEP 309). Then, the paper feed control unit 118 transmits an error signal to the control unit 10 to notify the occurrence of an abnormality in the paper feed operation (SETP310). Therefore, when the CPU 101 receives an error signal from the paper feed control unit 118 in the control unit 10, the CPU 101 operates the operation panel 9 or the like so as to perform a notification operation such as a display indicating a paper feed abnormality in the paper feed device 8. Let Thereafter, the paper feed control unit 118 ends the abnormality determination control operation in STEP 202 (STEP 311).

  When the paper feed control unit 118 ends the abnormality determination control operation of STEP 202 (STEP 311), the paper feed control unit 118 checks whether or not the paper feed operation can be retried based on the flag set in the abnormality determination control operation, and controls the feeding roller 81. Therefore, a retry control operation is performed (STEP 203). When the paper feeding control unit 118 shifts to the retry control operation, as shown in the flowchart of FIG. 9, first, it is confirmed whether or not the end flag F3 is set (STEP 401). At this time, if the end flag F3 is not set (NO in STEP 401), the paper feed control unit 118 next checks whether or not the first retry flag F1 is set (STEP 402).

  Upon confirming the setting of the first retry flag F1 (YES in STEP 402), the paper feed control unit 118 notifies the control unit 10 to delay the image formation timing on the recording paper P2 by a predetermined time ΔT (STEP 403). . As a result, when the CPU 101 receives a delay of the time ΔT with respect to the image formation timing, the control unit 10 notifies the transfer control unit 115 and the fixing control unit 116 of the delay of the time ΔT. Therefore, the toner image forming operation and the transfer operation in the transfer unit 5 and the image fixing operation in the fixing unit 16 are started with a delay of time ΔT, respectively.

  Thereafter, the paper feed control unit 118 checks the elapse of the predetermined time ΔT in order to perform the first retry operation for extending the driving time of the feeding roller 81 by the predetermined time ΔT (STEP 404). Then, when the passage of the predetermined time ΔT is confirmed (YES in STEP 404), the paper feed control unit 118 resets the first retry flag F1 (STEP 405).

  If the first retry flag F1 is not set in STEP 402 (No), the paper feed control unit 118 further checks whether or not the second retry flag F2 is set (STEP 406). Upon confirming the setting of the second retry flag F2 (YES in STEP 406), the paper feed control unit 118 notifies the control unit 10 to delay the image formation timing on the recording paper P2 by time T (STEP 407). As a result, when the CPU 101 receives the notification of the delay of the time T with respect to the image formation timing, the control unit 10 notifies the transfer control unit 115 and the fixing control unit 116 of the delay of the time T as in STEP 404.

  Then, the paper feed control unit 118 first stops the feed roller 81 in order to perform the second retry operation by restarting the feed roller 81 (STEP 408). At this time, when it is confirmed that the feeding roller 81 has stopped (YES in STEP 409), the sheet feeding control unit 118 rotates the feeding roller 81 again to start the sheet feeding operation (STEP 410). Thereafter, the paper feed controller 118 checks whether or not a predetermined time T has elapsed after starting the paper feed operation in STEP 410 (STEP 411). When the predetermined time T has elapsed after the sheet feeding device 8 performs the sheet feeding operation by the second retry operation (Yes in STEP 411), the sheet feeding control unit 118 resets the second retry flag F2 (STEP 412). ).

  When the first or second retry flag F1 or F2 is reset in any one of the above STEP 405 and STEP 412, the paper feed control unit 118 counts the number of retries N for one time (STEP 413), and then proceeds to STEP 302. . On the other hand, when the end flag F3 is set (Yes in STEP 401) or when the error flag F4 is set (No in STEP 406), the retry control operation is ended (STEP 414).

When the paper feed control unit 118 ends the retry control operation of STEP 203 (STEP 414),
Based on the flag set in the abnormality determination control operation, a paper feed stop control operation is performed to stop the feeding roller 81 (STEP 204). When the paper feed control unit 118 shifts to the paper feed stop control operation, as shown in the flowchart of FIG. 10, first, it is confirmed whether or not the end flag F3 is set (STEP 501). At this time, when the end flag F3 is set (No in STEP501), the paper feed control unit 118 determines whether or not the end detection signal indicating the end of the recording paper P2 has been received from the paper feed state detection unit 85. Confirm (STEP 502).

  For example, when it is confirmed that the image data acquired by the image sensor 852 matches the image data acquired last time, the paper supply state detection unit 85 passes the end of the recording paper P2 through the paper supply state detection unit 85. As a result, the end detection signal may be transmitted to the paper feed control unit 118. At this time, the paper feed state detection unit 85 sends an end detection signal to the paper feed control unit 118 when the area that matches the previously acquired image data exceeds the predetermined area in the image data acquired by the image sensor 852. It does not matter if it is sent.

  Upon receiving the end detection signal from the paper feed state detection unit 85 (YES in STEP 502), the paper feed control unit 118 drives the feed roller 81 to rotate after a predetermined time Tx has elapsed from the end of the end detection signal (YES in STEP 503). The operation is stopped (STEP 504), and the paper feed stop control operation is terminated (STEP 505). In STEP 501, if the paper feed control unit 118 does not confirm the end flag F3 set (No), the feed roller 81 rotates to stop the paper feed operation in order to confirm the error flag F4 set. After the driving is stopped (STEP 504), the paper feed stop control operation is ended (STEP 505).

  By performing the sheet feeding control operation as described above, when the sheet feeding by the feeding roller 81 is delayed, the subsequent image forming operation can be performed normally only by extending the sheet feeding operation by ΔT. . Further, even when a paper slip occurs in the feeding operation of the recording paper P2 by the feeding roller 81, the image forming operation can be performed normally by stopping the feeding operation and then restarting it. Further, even if the resuming operation (retry operation) of the feeding roller 81 is repeated N1 times (for example, 2 to 3 times) or more, if the recording paper P2 is still fed, the feeding operation is performed. When it is determined that an abnormality has occurred and the paper feeding operation is stopped, it is possible to notify the outside that an abnormality has occurred in the paper feeding operation by the paper feeding device 8.

<Another example 1 of sheet feeding control operation>
In this example, unlike the above-described paper feed control operation, the movement speed V of the recording paper P2 is detected, and the retry operation is performed as either the first or second retry operation based on the movement speed V of the recording paper P2. Decide what to do. In other words, in this example, in the abnormality determination control operation (STEP 202) in the above-described paper feed control operation, which of the first and second retry flags F1 and F2 is to be set is determined based on the moving speed V of the recording paper P2. Determine based on. Therefore, in the following, the abnormality determination control operation in the paper feed control operation of this example will be described below with reference to the flowchart of FIG.

  In this example, as shown in the flowchart of FIG. 11, when the paper feed control unit 118 performs the abnormality determination control operation (STEP 202) and confirms that the determination timing has been reached (YES in STEP 301), the displacement information of the recording paper P2 As a result, not only the movement amount M but also the movement speed V is received from the paper feed state detection unit 85 (STEP 302 and STEP 321). Thereafter, when the paper feed control unit 118 confirms that the moving amount M of the recording paper P2 is less than the first reference value M1 and the number of retries N is equal to or less than the predetermined number N1 (Yes in STEP 303 and STEP 304, respectively). The moving speed V of the recording paper P2 is compared with the second reference value V2 (STEP 322). The second reference value V2 is a value determined by the rotational speed of the feeding roller 81, and is smaller than the rotational speed of the feeding roller 81.

  The paper feed control unit 118 confirms that the moving speed V of the recording paper P2 is greater than the second reference value V2 and is close to the rotating speed (set speed) of the feeding roller 81 (Yes in STEP322). The first retry flag F1 is set (STEP 306). In other words, the paper feed control unit 118 determines that there is a delay in the feeding of the recording paper P2 but that no abnormality has occurred in the paper feeding operation itself, so that the rotation of the feeding roller 81 is extended. The first retry flag F1 is set.

  On the other hand, when the paper feed control unit 118 confirms that the moving speed V of the recording paper P2 is equal to or lower than the second reference value V2 and the movement of the recording paper P2 is extremely small (No in STEP322), the second retry flag F2 is set (STEP307). That is, the paper feed control unit 118 sets the second retry flag F <b> 2 to temporarily stop and rotate the feeding roller 81 in order to determine that the paper slip has occurred in the feeding roller 81.

  In the abnormality determination control operation of this example, the operations other than the operations until the first and second retry flags F1 and F2 are set are the same as the above-described paper feed control operation. Omitted. In the subsequent retry control operation (STEP 203), similarly to the above-described paper feed control operation, the paper feed control unit 118 performs the first and second feeding rollers 81 according to the first and second retry flags F1 and F2. Control the second retry operation.

<Another example 2 of sheet feeding control operation>
In this example, unlike the above-described paper feed control operation, when the first retry operation is performed, the rotation speed of the feeding roller 81 changes according to the amount of movement M of the recording paper P2 obtained in STEP 302. Let That is, in this example, when the first retry flag F1 is set in the retry control operation (STEP 203) in the above-described paper feed control operation, the smaller the movement amount M, the slower the rotation speed of the feeding roller 81. Is set to be Accordingly, the retry control operation in the paper feed control operation of this example will be described below with reference to the flowchart of FIG.

  In this example, as shown in the flowchart of FIG. 12, when the paper feed control unit 118 performs the retry control operation (STEP 203), if the end flag is not set (NO in STEP 401), the first retry is performed. If it is confirmed that the flag F1 is set (YES in STEP 402), the rotation speed of the feed roller 81 is set (STEP 421). At this time, the rotation speed of the feed roller 81 is set to a value that is proportional to the ratio (M / M1) of the movement amount M of the recording paper P2 to the first reference value M1, for example, and is slower as the movement amount M is smaller. It is good also as what is set up to become. Further, the rotation speed of the feeding roller 81 may be set so as to increase when the movement amount is small, and may be set stepwise according to the magnitude of the movement amount M.

  After setting the rotation speed of the feeding roller 81, the paper feed control unit 118 sets an extension time ΔT of the driving time of the feeding roller 81 (STEP 422). That is, the paper feed control unit 118 sets the extension time ΔT in accordance with the rotation speed of the feed roller 81 set in STEP 421. Therefore, when the rotation speed of the feed roller 81 is set to a small value, the extension time ΔT is long. Is set. Then, the paper feed control unit 118 notifies the control unit 10 to delay the image formation timing on the recording paper P2 by the extension time ΔT set in STEP 422 (STEP 403). Thereafter, when it is confirmed that the set extension time ΔT has elapsed (YES in STEP 404), the paper feed control unit 118 resets the first retry flag F1 (STEP 405).

  In the retry control operation of this example, the operations other than the first retry operation are the same as the above-described paper feed control operation, and thus detailed description thereof is omitted. In this example, when the first retry operation is performed, the rotation speed of the feeding roller 81 is decreased according to the movement amount M of the recording paper P2, but the recording paper P2 as in the above-described another example 1. Can be measured, the rotation speed of the feed roller 81 may be set to a value proportional to the movement speed V of the recording paper P2.

  Further, when the rotation speed of the feeding roller 81 is set according to the moving speed V of the recording paper P2 and the first retry operation is performed, the rotating speed of the feeding roller 81 that is set is based on the moving speed V of the recording paper P2. May be set to a faster value. At this time, the paper feed control unit 118 confirms the moving speed of the recording paper P2 during the first retry operation. When the moving speed of the recording paper P2 becomes equal to the rotating speed of the feeding roller 81, the rotation of the feeding roller 81 is performed. The speed may be gradually increased.

  In this example, even when the paper feed control unit 118 confirms the setting of the second retry flag F2 (YES in STEP 406), the rotation speed of the feeding roller 81 in STEP 410 is set to the moving amount M of the recording paper P2. Alternatively, it may be changed according to the moving speed V. Further, depending on the amount of movement M or moving speed V of the recording paper P2, instead of stopping the feeding roller 81 in STEP 408, the rotation speed of the feeding roller 81 may be slowed down. At this time, after confirming that the moving speed of the recording paper P2 is equal to the rotational speed of the feeding roller 81, the rotational speed of the feeding roller 81 is gradually increased until reaching the design value.

<Another example 3 of paper feed control operation>
In this example, unlike the above-described sheet feeding control operation, the values of the first and second reference values M1 and M2 are changed based on the driving time of the feeding roller 81. That is, the paper feed control unit 118 accumulates the time during which the feeding roller 81 is driven with a counter or the like, and stores the accumulated value as the drive time (drive amount). Then, in the abnormality determination control operation (STEP 202) in the above-described paper feed control operation, the paper feed control unit 118 predicts the wear amount from the driving time of the feed roller 81, and when the predicted wear amount of the feed roller 81 is large, The values of the first and second reference values M1, M2 are set so that the first and second reference values M1, M2 are small. Accordingly, the abnormality determination control operation in the paper feed control operation of this example will be described below with reference to the flowchart of FIG.

  In this example, as shown in the flowchart of FIG. 13, when performing the abnormality determination control operation (STEP 202), the paper feed control unit 118 first reads the driving time of the feeding roller 81 and predicts the wear amount of the feeding roller 81. (STEP331). Then, the paper feed control unit 118 sets the first and second reference values M1 and M2, which are the determination criteria in STEPs 303 and 305, according to the read driving time of the feeding roller 81 (STEP 332). At this time, as the driving time of the feeding roller 81 becomes longer, the sizes of the first and second reference values M1 and M2 are set to smaller values. After that, the paper feed control unit 118 compares the set first and second reference values M1 and M2 with the moving amount M of the recording paper P2 in the same manner as the paper feed control operation described above, and thereby flags F1 to F4. Set one of the following.

  Thus, in this example, each of the first and second reference values M1 and M2 is set to be smaller as the driving time of the feeding roller 81 is longer. That is, when the amount of wear of the feeding roller 81 is increased, the friction of the feeding roller 81 on the recording paper P2 is reduced, so that the moving speed of the recording paper P2 is reduced. At this time, since each of the first and second reference values M1 and M2 is set to be small, the rate at which it is determined that the paper feed is abnormal is low. Therefore, by changing the first and second reference values M1 and M2 as in this example, optimal control can be performed according to the wear state of the feeding roller 81.

<Other example 4 of paper feed control operation>
In this example, unlike the above-described paper feed control operation, the values of the first and second reference values M1 and M2 are changed based on the type of the recording paper P2. That is, the paper feed control unit 118 stores the type of the recording paper P2 stored in the paper feed tray 4 where the paper feed operation is performed. In the abnormality determination control operation (STEP 202) in the paper feed control operation described above, The type of the stored recording paper P2 is read out. Then, if the recording paper P2 is of a type having a high surface smoothness, the paper feed control unit 118 makes the first and second reference values M1, M2 so that the first and second reference values M1, M2 become small. Set the value of. Hereinafter, the abnormality determination control operation in the paper feed control operation of this example will be described below with reference to the flowchart of FIG.

  In this example, as shown in the flowchart of FIG. 14, when performing the abnormality determination control operation (STEP 202), the paper feed control unit 118 first reads the type of the recording paper P2, and smoothes the surface of the recording paper P2. Recognize (STEP 341). Then, the paper feed control unit 118 sets the first and second reference values M1 and M2 that are the determination criteria in STEPs 303 and 305 according to the type of the read recording paper P2 (STEP 332). At this time, the higher the smoothness of the surface of the recording paper P2, the smaller the sizes of the first and second reference values M1 and M2 are set. After that, the paper feed control unit 118 compares the set first and second reference values M1 and M2 with the moving amount M of the recording paper P2 in the same manner as the paper feed control operation described above, and thereby flags F1 to F4. Set one of the following.

  Thus, in this example, each of the first and second reference values M1 and M2 is set to be smaller as the surface smoothness of the recording paper P2 is higher. That is, the smoothness of the surface of the recording paper P2 is high, and when the friction with respect to the recording paper P2 by the feeding roller 81 is reduced, the moving speed of the recording paper P2 is reduced. At this time, since each of the first and second reference values M1 and M2 is set to be small, the rate at which it is determined that the paper feed is abnormal is low. Accordingly, in this example as well, as in the above-described third example, the first and second reference values M1 and M2 can be changed to optimally control according to the type of the recording paper P2.

  In addition, by combining the above-described alternative example 3 with another example 4 of the paper feed control operation, the first and second reference values M1 and M2 are set according to both the wear amount of the feeding roller 81 and the type of the recording paper P2. It can be changed. Further, in the other examples 1 and 2 of the sheet feeding control operation, the operations as in the above other examples 3 and 4 may be combined.

  Further, the image forming apparatus according to the present invention has been described by taking an electrophotographic image forming apparatus as an example. However, the image forming apparatus is not limited to the electrophotographic system, and may be an image forming apparatus using another system such as an ink jet system. . Further, the image forming apparatus according to the present invention may be an MFP (Multifunction Peripheral) having a copy function, a scanner function, a printer function, and a fax function, or may be a printer, a copier, a facsimile, or the like. In addition, the structure of each part is not limited to embodiment of illustration, A various change is possible in the range which does not deviate from the meaning of this invention.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Apparatus main body 3 Image reading part 4 Paper feed tray 5 Transfer part 6 Fixing part 7 Paper discharge tray 8 Paper feed device 9 Operation panel 10 Control part 31 Scanner part 32 Automatic document conveyance part (ADF)
33 Document Plate 34 Light Source 35 Image Sensor 36 Imaging Lens 37 Mirror Group 38 Document Placement Tray 39 Document Ejection Tray 40 Document Conveying Mechanism 51 Image Forming Unit 52 Exposure Unit 53 Intermediate Transfer Belt 54 Primary Transfer Roller 55 Drive Roller 56 Followed Roller 57 Secondary transfer roller 58 Cleaner unit 59 Heating roller 60 Pressure roller 61 Photosensitive drum 62 Charger 63 Developer 64 Cleaner unit 81 Feeding roller 84 Vertical conveyance roller pair 85 Paper feed state detection unit 86 Conveyance state detection unit 87 Timing roller Pair 88,90 Recording paper detector 91 Paper discharge roller pair 93 Manual feed tray 101 CPU
102 ROM
103 RAM
DESCRIPTION OF SYMBOLS 104 Image processing part 105 Image memory 106 Input / output interface 110 Communication network 113 Image reading control part 114 Exposure control part 115 Transfer control part 116 Fixing control part 118 Paper feed control part 851 Light source 852 Image sensor

Claims (15)

A paper feed tray for storing recording paper; an image forming unit for forming an image on the recording paper; a transport path for transporting the recording paper to the image forming unit; and the recording paper from the paper feed tray to the transport path An image forming apparatus comprising a feeding roller for feeding
A paper feed state detection unit that measures the transport state of the recording paper stored in the paper feed tray on the upstream side of the feeding roller along the recording paper transport direction;
A sheet feeding control unit that receives a measurement result from the sheet feeding state detection unit and controls a driving operation of the feeding roller;
With
The paper feeding control unit drives the feeding roller to start feeding the recording paper from the paper feeding tray, and then feeds the recording paper detected by the paper feeding state detection unit. An image forming apparatus, wherein when receiving displacement information indicating a conveyance state on a tray, a driving state of the feeding roller is set based on the displacement information. The displacement information from the paper feed state detection unit is the amount of movement of the recording paper after a predetermined time has elapsed since the start of paper feed,
2. The image forming apparatus according to claim 1, wherein the sheet feeding control unit causes a retry operation by the feeding roller to be performed when the amount of movement of the recording sheet received from the sheet feeding state detection unit is small. .   3. The image according to claim 2, wherein the paper feed control unit determines that the recording paper is normally fed when the moving amount of the recording paper is larger than a first reference value. 4. Forming equipment.   The sheet feeding control unit is configured to perform the recording by the feeding roller when the amount of movement of the recording sheet is equal to or less than the first reference value and the amount of movement is equal to or greater than a second reference value smaller than the first reference value. The first retry operation for extending the paper feeding is performed, and after the elapse of the extension time due to the first retry operation, the movement amount of the recording paper from the paper feed state detection unit is received again, 4. The image forming apparatus according to claim 3, wherein it is determined whether or not the recording paper is fed normally.   The paper feed control unit is configured such that when the movement amount of the recording paper is equal to or less than the first reference value and the movement amount is smaller than a second reference value smaller than the first reference value, the recording paper by the feeding roller is A second retry operation for re-driving the feed roller after temporarily stopping the feeding of the feed roller, and again after a predetermined time has elapsed from the start of the second retry operation, 5. The image forming apparatus according to claim 3, wherein the image forming apparatus determines whether the recording paper is in a normal feeding state based on a movement amount of the recording paper. The displacement information from the paper feed state detection unit is the moving speed of the recording paper after a predetermined time has elapsed since the start of paper feed,
The image forming apparatus according to claim 1, wherein the sheet feeding control unit causes the feeding roller to perform a retry operation when the moving speed of the recording sheet received from the sheet feeding state detection unit is low. .   The image forming apparatus according to claim 6, wherein the feeding control unit extends the feeding of the recording paper by the feeding roller when the retry operation is performed by the feeding roller.   The paper feeding control unit, when performing a retry operation by the feeding roller, temporarily stops feeding of the recording paper by the feeding roller and then drives the feeding roller again. 8. The image forming apparatus according to 7.   The sheet feeding control unit integrates the driving time of the feeding roller, and sets a determination criterion as to whether or not to perform a retry operation by the feeding roller based on the driving time of the feeding roller. The image forming apparatus according to claim 2.   The sheet feeding control unit sets a determination criterion as to whether or not to perform a retry operation by the feeding roller based on the type of the recording sheet. The image forming apparatus described.   The paper feeding control unit sets a rotation speed of the feeding roller based on displacement information from the paper feeding state detection unit when performing a retry operation by the feeding roller. The image forming apparatus according to any one of 10.   12. The image forming unit according to claim 2, wherein when the paper feeding control unit performs a retry operation by the feeding roller, the timing of image formation in the image forming unit is delayed by a time required for the retry operation. The image forming apparatus according to any one of the items.   The paper feeding control unit determines that an abnormality has occurred in the paper feeding operation of the recording paper by the feeding roller when the number of times of performing the retry operation by the feeding roller exceeds a predetermined number. The image forming apparatus according to any one of claims 2 to 12.   The sheet feeding control unit stops the rotation operation of the feeding roller after a predetermined time has elapsed since the sheet feeding state detection unit is notified that the movement of the recording sheet is no longer detected. The image forming apparatus according to claim 1.   2. The paper feeding state detection unit is configured by a light source that irradiates light to the recording paper and an image sensor that receives reflected light of the recording paper based on light from the light source. The image forming apparatus according to claim 14.

Images