JP2008013338A - Sheet feeder, and image forming device equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promptly recognize the length of a fed recording material at low cost without making user's work intervene when an image forming device recognizes the length of a sheet. <P>SOLUTION: This paper feeder delivering sheets S one by one from a manual tray 32 is provided with a rear end detection device 60 detecting that the rear end of a delivered sheet has passed a predetermined rear end detection position P1 in the manual tray. According to this structure, time from start of the delivery of the sheet to detection of the rear end of the sheet is shorter than time required for transporting the length portion of one sheet. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a feeding device that feeds recording materials of a recording material setting section capable of setting recording materials of a plurality of sizes having different lengths in the recording material conveyance direction one by one, and an image forming apparatus including the feeding device.

  In image forming apparatuses such as copiers, facsimiles, and printers, regardless of the image forming method such as the electrophotographic method or the ink jet method, the paper (recording material) set in the paper feed tray (recording material setting unit) If the size, particularly the length of the paper in the paper conveyance direction (hereinafter simply referred to as “length”) is not accurately grasped, the following problems will occur.

Some image forming apparatuses are provided with a jam detection sensor in the paper conveyance path. In this image forming apparatus, even if the paper having the same length as the length of paper grasped by the image forming apparatus is already passed through the jam detection sensor, the jam detection sensor is also It is determined that a jam has occurred while detecting. For this reason, if a sheet longer than the length of the sheet grasped by the image forming apparatus is actually conveyed, it is determined that a jam has occurred even though the jam has not actually occurred. A malfunction occurs.
Further, even in an image forming apparatus that does not include such a jam detection sensor, the sheet conveyance is usually stopped at a timing when a grasped length of sheet is discharged. For this reason, if a sheet longer than the length of the sheet grasped by the image forming apparatus is actually conveyed, the conveyance of the sheet is stopped before the sheet is completely discharged, and an appropriate discharge is performed. There is a problem that it cannot be done.

  Conversely, when a sheet shorter than the length of the sheet grasped by the image forming apparatus is actually conveyed, the sheet is formed while the image forming unit is forming an image on the sheet being conveyed. Will pass through the department. As a result, a large amount of image forming material (ink, toner, etc.) adheres to a place other than the paper, causing a problem that the inside of the image forming apparatus is contaminated.

  Conventionally, the position of the end fence that regulates the setting position of the trailing edge of the paper in the paper feed tray can be moved, and the position of the end fence can be detected to detect the position of the paper set in the paper feed tray. An image forming apparatus for grasping the length is widely known (Patent Document 1, Patent Document 2, etc.). In such an image forming apparatus, in general, when a sheet is set in the sheet feeding tray, the position of the end fence is adjusted and fixed so that the user manually regulates the setting position on the rear end side of the sheet. Do the work. If the user appropriately performs this operation, the length of the sheet grasped by the image forming apparatus matches the length of the sheet actually fed from the sheet feeding tray, and the above-described problem does not occur.

JP 2001-187463 A JP 2004-115136 A

  However, in reality, there are many mistakes in the above-mentioned work by the user, the end fence is often not fixed at a position corresponding to the paper set in the paper feed tray, and the above-mentioned problems still occur. Is the current situation. Therefore, the present inventor conducted research on measures for eliminating problems caused by user's work mistakes.

  In the research conducted by the inventor, first of all, attention is paid to the fact that many image forming apparatuses have a sensor for detecting the passage of paper in the paper transport path, and the length of the paper is grasped by using the sensor. We examined how to do this. In this measure, since the paper conveyance speed is a predetermined constant speed, the length of the paper is measured by measuring the time from when the sensor detects the leading edge of the paper until the trailing edge of the paper is detected. This is based on the fact that it is possible to grasp this. According to this measure, since it is not necessary for the image forming apparatus to intervene the user's work when grasping the length of the sheet, it is possible to prevent the above-described problems from occurring due to a user's work mistake. However, in this measure, the image forming apparatus grasps the length of the sheet after the trailing end of the sheet passes through the detection position of the sensor. For this reason, when the image forming apparatus grasps the length of the sheet, the leading edge of the sheet is conveyed far ahead, and it is determined that a jam has occurred even though the jam has not actually occurred. There has been a problem in that there are cases where it is not possible to solve problems such as problems and contamination of the inside of the image forming apparatus with image forming substances. In order to grasp the length of the paper as early as possible, it is considered to use a sensor as close as possible to the paper feed tray, specifically, a registration sensor arranged on the upstream side in the paper conveyance direction of the registration roller pair. However, there is a case where the above-described jam problem cannot be solved even if a resist sensor is used.

  Further, among electrophotographic color image forming apparatuses, those adopting an intermediate transfer method are becoming mainstream. In such an image forming apparatus, since it takes a long time from the start of image formation on the latent image carrier to the transfer of the resulting image to the recording material, the registration sensor is used to grasp the length of the paper. Even in this case, the image forming process has advanced considerably when the image forming apparatus grasps the length of the sheet. For this reason, a large amount of toner is wasted, which is uneconomical.

  In addition, although a measure to grasp the paper size set in the paper feed tray with a large number of sensors can be considered, since this measure increases the number of sensors or the configuration becomes complicated, the cost increases. Not realistic.

  The present invention has been made in view of the above background, and an object of the present invention is to provide an image forming apparatus that does not require any user work when grasping the length of a sheet, and that can be supplied at low cost. It is an object of the present invention to provide a feeding device capable of quickly grasping the length of a paper-recorded recording material and an image forming apparatus provided with the feeding device.

In order to achieve the above object, the invention of claim 1 is a recording material set portion capable of setting recording materials of a plurality of sizes having different lengths in the recording material conveyance direction, and one recording material from the recording material set portion. And a feeding device that feeds the recording material each time. The feeding device includes a detecting unit that detects that the trailing edge of the recording material fed by the feeding unit has passed a predetermined trailing edge detection position in the recording material setting unit. It is what.
According to a second aspect of the present invention, in the feeding device according to the first aspect, a detection position changing means is provided for changing the predetermined rear end detection position in the recording material setting section along the recording material conveyance direction. It is a feature.
According to a third aspect of the present invention, in the feeding device according to the first aspect, a plurality of the predetermined rear end detection positions are provided in the recording material setting portion along the recording material conveyance direction.
According to a fourth aspect of the present invention, in the feeding device according to the first, second, or third aspect, the feeding means is located at the top of a plurality of recording materials set in a stacked state on the recording material setting portion. The uppermost recording material is sent out, and the detection means detects a rotating body that contacts the upper surface of the uppermost recording material and can rotate as the recording material moves, and a rotation stop of the rotating body. A rotation stop detection unit that detects that the rear end of the uppermost recording material has passed the predetermined rear end detection position when the rotation stop detection unit detects rotation stop of the rotating body. It is characterized by being.
According to a fifth aspect of the present invention, in the feeding device according to the first, second, third, or fourth aspect, the feeding means is provided on the top of a plurality of recording materials set in a stacked state on the recording material setting portion. The uppermost recording material is sent out, and the detecting means uses a facing member facing the upper surface of the uppermost recording material, and the rear end of the uppermost recording material detects the predetermined rear end detection position. Detects the passage of the counter member, the counter member facing the top surface of the uppermost recording material, and the counter member exists at the counter position when the recording material is set in the recording material setting section. A moving means for moving the opposing member is provided between the retracted position that does not interfere with the set as compared with the case of doing so.
According to a sixth aspect of the present invention, in the feeding device of the fifth aspect, an openable / closable dust-proof cover that covers an opening provided in the recording material set portion for setting the recording material in the recording material set portion is provided. When the dust cover is used as the moving means by attaching the counter member to the dust cover, the counter member takes the counter position when the dust cover is closed, and the dust cover is opened. A feeding device configured such that the opposing member takes the retracted position.
According to a seventh aspect of the present invention, in the image forming apparatus for forming an image on the recording material fed from the feeding device, the feeding device according to the first, second, third, fourth, fifth or sixth aspect. Using the feeding device, after the feeding means provided in the feeding device sends out the recording material, based on the detection result of the detecting means provided in the feeding device, recording material conveyance of the recording material sent out by the sending means It has a processing means for performing processing according to the direction length.
According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the processing means performs the processing based on an elapsed time from the start of sending by the sending means to the time of detection by the detecting means. It is a feature.
According to a tenth aspect of the present invention, in the image forming apparatus according to the seventh or eighth aspect, size information including a recording material conveyance direction length of a recording material set in the recording material setting portion provided in the feeding device is input. And a storage unit for storing the size information input to the input unit. The processing performed by the processing unit is stored in the storage unit after the sending unit sends out the recording material. The recording material conveyance direction length included in the size information is compared with the recording material conveyance direction length ascertained based on the detection result of the detection means, and if the two do not match, input to the input means Notification processing for notifying that the size information is incorrect is included.
According to an eleventh aspect of the present invention, in the image forming apparatus according to the seventh, eighth, ninth, or tenth aspect, the recording material setting portion provided in the feeding device is a recording material setting portion for manual feeding. It is a feature.
According to a twelfth aspect of the present invention, the image forming apparatus according to the seventh, eighth, ninth, tenth, or eleventh aspect includes a plurality of the feeding devices.
According to a thirteenth aspect of the present invention, in the image forming apparatus according to the seventh, eighth, ninth, tenth, eleventh or twelfth aspect, the processing performed by the processing means is performed by the detection means after the sending means sends out the recording material. The image forming operation is stopped before the start of image formation on the rear side in the recording material conveyance direction from the trailing edge of the recording material having the length in the recording material conveyance direction grasped based on the detection result of It is the process to perform.
According to a fourteenth aspect of the present invention, in the image forming apparatus according to the seventh, eighth, ninth, tenth, eleventh, twelfth or thirteenth aspect, at least one of a leading edge and a trailing edge of the recording material fed by the feeding means is detected in a predetermined manner. Another detecting means for detecting the passage of the position, and the processing means is based on the detection result of the detecting means and the detection result of the other detecting means after the sending means sends out the recording material. The above processing is performed.

In the present invention, the detecting means detects that the trailing edge of the recording material sent out by the sending means has passed a predetermined trailing edge detection position in the recording material setting portion. When detecting the trailing edge of the recording material by the detecting means provided downstream of the recording material setting portion as in the prior art, the detecting means performs recording after the sending means starts feeding the recording material. The time until the trailing edge of the material is detected is longer than the time required for conveying the length of the recording material. On the other hand, according to the present invention, the time from when the feeding means starts feeding the recording material until the detection means detects the trailing edge of the recording material is equivalent to the length of the recording material being conveyed. It will be shorter than the time required. Since the trailing edge of the recording material can be detected at an early stage in this way, the length of the recording material sent out by the sending means can be grasped at an early stage.
For example, when the front and rear ends of a recording material are individually detected by two detection means, the length of the recording material is grasped when the detection timings of both the front and rear ends of the recording material are grasped. Can do. That is, the distance between the detection positions of the two detection means and the conveyance speed of the recording material can be grasped in advance. As a result, even if the detection timing of the leading edge and the trailing edge of the recording material fluctuates, The length of the recording material can be grasped. And since it is easy even with the conventional configuration to detect the leading edge of the recording material, for example, by using a resist sensor, according to the present invention, when the trailing edge of the recording material can be detected early, It becomes possible to grasp | ascertain the length of this at an early stage.
Further, for example, if the timing at which the sending unit sends out the recording material is used, even the trailing edge of the recording material is detected at an early stage so that the length of the sheet can be grasped at the time of detection of the trailing edge. That is, the distance L ₁ between the leading edge position of the recording material set in the recording material setting portion (that is, the recording material before being sent out by the sending means) and the trailing edge detection position can be grasped in advance. Then, the distance L ₂ between the rear end position and the rear end detecting position of the recording material in a state of being set in the recording material setting section, since the conveyance speed of the recording material can be grasped in advance, sending means send out the recording material Can be obtained by grasping the conveyance time from when the detecting means detects the rear end. Since the length L of the sheet is (L ₁ + L ₂ ), the length L of the sheet can be grasped when the conveyance time is grasped, that is, when the detection unit detects the trailing edge. it can.
Furthermore, in the present invention, no user operation is required for the image forming apparatus to grasp the length of the sheet, and the detection means can be realized with a simple configuration, so that the cost does not increase.

  As described above, according to the present invention, when the image forming apparatus grasps the length of a sheet, it is not necessary to intervene the user's work, and the length of the fed recording material can be grasped at a low cost at an early stage. There is an excellent effect that becomes possible.

  Hereinafter, an embodiment in which the present invention is applied to a copying machine which is an electrophotographic image forming apparatus will be described. The present invention can be similarly applied to an image forming apparatus other than a copying machine, and can be similarly applied to a system other than an electrophotographic system, for example, an inkjet image forming apparatus.

FIG. 2 is a longitudinal front view showing an outline of the internal structure of the copying machine according to the present embodiment.
FIG. 3 is an enlarged front view of the manual sheet feeding mechanism.
FIG. 4 is an exploded perspective view illustrating a part of the manual sheet feeding mechanism.
The copier 1 of this embodiment includes a printer engine (image forming unit) 2, a cassette sheet feeding mechanism unit 3 having a plurality of sheet feeding cassettes 51 constituting a sheet feeding device as a feeding device, a fixing unit 4, and the like. It is provided in the apparatus body 5. Further, a sheet feeding device 8 including a sheet reversing mechanism unit 6 and a manual sheet feeding mechanism unit 7 constituting a sheet feeding device as a feeding device is attached to a side surface portion of the apparatus main body 5. In the apparatus main body 5, a conveyance path (two-dot chain line in the figure) 9 for conveying the paper S as a recording material toward a paper discharge tray (not shown) is formed, and along this conveyance path 9, registration rollers A pair 11, a printer engine 2, a fixing unit 4, and the like are arranged.

  The printer engine 2 includes a drum-shaped photosensitive member 12, a charger 13 as a charging unit disposed around the photosensitive member 12, an exposure unit 14 as a latent image forming unit, a developing unit 15 as a developing unit, and a transfer unit. The transfer device 16, the cleaning device 17 as a cleaning unit, the paper transport belt 47 as a recording material transport member, and the like. At the time of image formation by the copying machine 1, the surface of the photoreceptor 12 is uniformly charged by the charger 13, and light (for example, laser light) corresponding to image data read by a scanner unit (not shown) is exposed to the exposure device 14. The surface of the photoconductor 12 is exposed to this light, and an electrostatic latent image is formed on the surface of the photoconductor 12. Toner supplied from the developing device 15 adheres to the electrostatic latent image, and the electrostatic latent image is visualized as a toner image. The visualized toner image is transferred by the transfer action of the transfer device 16 to the paper S transported through the transport path 9 while being carried on the surface of the paper transport belt 47. The sheet S on which the toner image is transferred is conveyed on the conveyance path 9 and sent to the fixing unit 4, and the toner image is fixed on the sheet S by being heated and pressurized by the fixing unit 4. The sheet on which the toner image is fixed is discharged onto a discharge tray (not shown). The toner remaining on the photoconductor 12 after the toner image is transferred is cleaned by the cleaning device 17.

  In the middle of the transport path 9, a reversal discharge path 18 is branched downstream from the fixing unit 4 along the transport direction of the paper S, and the transport direction of the paper S is discharged to this branched portion. A switching claw 19 is provided for switching to either the tray side or the reverse discharge path 18 side. Further, on the upstream side of the registration roller pair 11, a common paper feed path 20 that is a common path through which any of the paper S in the paper feed cassette 51, the reversed paper S, or the manually fed paper S is fed is formed. ing. The common sheet feeding path 20 sufficiently sags a sheet portion (slack portion) existing between the pair of registration rollers 11 and the pair of rollers 10, 28, and 36 closest to the upstream side. It has enough space for it.

  The paper feeding device 8 includes a case 21 attached to a side surface of the apparatus main body 5, a paper reversing mechanism portion 6 provided in the case 21, and a manual paper feeding mechanism portion 7. The case 21 is formed by an upper case 21a and a lower case 21b connected to the lower side of the upper case 21a.

  The sheet reversing mechanism 6 includes an inlet path 22, a reversing path 23, and a refeed path 24 formed in the case 21. The inversion path 23 is formed by an upper inversion path 23a formed in the upper case 21a and a lower inversion path 23b formed in the lower case 21b. One end of the inlet path 22 communicates with the reversing paper discharge path 18 and the other end of the inlet path 22 is connected to the upper reversing path 23a. One end of the refeed path 24 is connected to the inlet path 22, and the other end of the refeed path 24 is connected to the common sheet feed path 20. A reversing roller pair 25 capable of rotating in the forward and reverse directions is provided at a connection portion between the inlet path 22 and the upper reversing path 23a. The reversing roller pair 25 rotates in the forward direction (clockwise direction), so that the sheet S sent from the reversing paper discharge path 18 to the inlet path 22 is sent to the reversing path 23. The reverse roller pair 25 rotates in the reverse direction (counterclockwise direction) after feeding the paper S to the reverse path 23 to a position where the rear end of the paper S in the feed direction is nipped by the reverse roller pair 25. By the rotation in the reverse direction, the paper S once sent to the reversing path 23 is sent out from the reversing path 23. At this time, since the switching claw 26 is switched to the position indicated by the virtual line, the sheet S sent out from the reversing path 23 is sent into the refeed path 24. In the middle of the refeed path 24, a pair of transport rollers 27 is provided as a transport means. The transport roller pair 27 is also located near the upstream end in the feed direction with respect to the downstream end of the refeed path 24 in the feed direction. A first feed roller pair 28 is provided.

  As shown in FIG. 3, the manual paper feed mechanism unit 7 includes a lower case 21b formed by connecting a housing 29, a first guide plate 30, and a second guide plate 31, and a manual feed tray as a recording material setting unit. A manual paper feed tray 32, a manual paper feed conveyance path 33, a pickup roller 34a constituting a feeding means, a separation roller pair 34b composed of a feed roller and a reverse roller, a pad 35, and a second feeding roller pair constituting a sending means. 36, a lower inversion path 23b, and the like. The pickup roller 34 a is configured to be able to contact with and separate from the pad 35. The manual paper feed tray 32 is provided so as to be rotatable about a fulcrum 37 between a use position and a non-use state. In FIG. 2, the manual paper feed tray 32 is positioned at the use position. The manually fed paper S is placed on the manual paper feed tray 32. After the paper S is placed on the manual paper feed tray 32, the pickup roller 34a is driven to rotate, so that the manual paper feed tray 32 is moved. Sheet S is delivered to the separation roller pair 34b. Thereafter, the sheet is separated one by one by the separation roller pair 34 b and conveyed on the manual sheet feeding conveyance path 33, and sent from the common sheet feeding path 20 onto the conveyance path 9.

  The first guide plate 30 is screwed to the housing 29, and this screwing is performed by inserting a screw (not shown) inserted into a round hole 38 formed in the first guide plate 30 into a screw hole 39 formed in the housing 29. This is done by screwing. The second guide plate 31 is screwed to the housing 29, and this screwing is performed by inserting a screw (not shown) inserted into a round hole 40 formed in the housing 29 into a screw hole 41 formed in the second guide plate 31. This is done by screwing. The housing 29 holds the separation roller pair 34b and the driving roller A of the second feeding roller pair 36 rotatably, and the second guide plate 31 holds the driven roller of the second feeding roller pair 36. B is rotatably held.

  A lower inversion path 23b is formed between the housing 29 and the first guide plate 30 screwed to the housing 29 in a direction intersecting with the manual sheet feeding conveyance path 33. The lower inversion path 23b and the upper inversion path 23a Are communicated to form the inversion path 23. The width dimension of the lower inversion path 23b and the upper inversion path 23a (the width dimension in the direction orthogonal to the paper surface) is formed to be the same dimension, and the sheet S sent to the upper inversion path 23a has its leading end in the feeding direction at the lower inversion path 23b. It is possible to get inside. The reversing path 23 formed by connecting the upper reversing path 23a and the lower reversing path 23b and the manual sheet feeding conveyance path 33 intersect in an inverted T shape. The lower end side of the reversing path 23 (the portion of the lower reversing path 23 b) is positioned on the downstream side of the separation roller pair 34 b along the transport direction of the paper S in the manual paper feed transport path 33. A plurality of ribs 42 are formed in a portion of the housing 29 facing the lower inversion path 23b along the width direction of the lower inversion path 23b (a direction orthogonal to the paper surface).

  The first guide plate 30 is formed with a plurality of ribs 43 arranged in the same direction as the arrangement direction of the ribs 42, and these ribs 43 are a part of the inner peripheral surface of the tip of the other end of the refeed path 24. Is forming. The first feed roller pair 28 is positioned in the vicinity of the portion where the ribs 43 are formed. The first feed roller pair 28 is formed by the driving roller A and the driven roller C, and the driving side roller C is formed on the driving side. The roller A is shared as the driving roller A of the second feeding roller pair 36. The driven roller C in the first feed roller pair 28 is rotatably held by the upper case 21a. The roller A is connected to a drive motor that can switch between forward and reverse rotation. When the paper S is fed from the manual paper feed tray 32, the roller A is driven to rotate in the forward direction (clockwise direction), and when the paper S is fed again from the refeed path 24, the roller A is rotated. A is driven to rotate in the reverse direction (counterclockwise direction).

  The outlet of the refeed path 24, the outlet of the manual sheet feed conveyance path 33, and the outlet of the cassette sheet feed conveyance path 52 are opened close to each other, and are all connected to the common sheet feed path 20 formed in the apparatus body 5. Communicate.

  As shown in FIG. 2, a sheet conveyed from the sheet cassette 51 provided in the apparatus body 5 toward the printer engine 2 is provided on the side surface of the apparatus body 5 and below the sheet feeder 8. When S is jammed in the cassette paper feeding / conveying path 52, an open / close cover 44 for opening the cassette paper feeding / conveying path 52 is attached so as to be openable / closable with the support shaft 45 as a fulcrum to handle the jam.

A case where images are formed on both sides of the sheet S by the copying machine 1 will be described.
The paper S fed from the paper feed cassette 51 or the manual paper feed tray 32 is transported through the transport path 9, and a toner image is transferred to one side of the paper S at the printer engine 2, and the toner image is transferred to the fixing unit 4. It is fixed. The sheet S on which the toner image is formed on one side by performing the fixing process in the fixing unit 4 is sent to the reverse discharge path 18 side by the switching claw 19 which is switched to the position shown by the solid line in FIG. Then, the paper is fed into the reverse path 23 via the reverse discharge path 18 and the inlet path 22. The rotation of the reverse roller pair 25 is stopped at the timing when the rear end portion of the sheet S sent to the reverse path 23 is sandwiched between the reverse roller pair 25, and then the reverse roller pair 25 is reversely rotated. By this reverse rotation, the sheet S sent to the reversing path 23 is sent out from the reversing path 23. At this time, the switching claw 26 has been switched to a position (a position indicated by an imaginary line in FIG. 2) for feeding the paper S sent out from the reversing path 23 to the refeed path 24. Is sent to.

  The sheet S sent to the refeed path 24 is transported by the transport roller pair 27 and the first feed roller pair 28, and is sent from the common paper feed path 20 to the transport path 9 in a state where the front and back sides are reversed. Then, after being transported through the transport path 9, the toner image is transferred to the other surface of the sheet S again at the printer engine 2. When the toner image is transferred to the sheet S for the second time, the switching claw 19 is switched to the position indicated by the phantom line in FIG. 2, and the sheet S on which the second toner image is transferred is the fixing unit. After the fixing process at 4, the paper is sent to the paper discharge tray side and discharged onto the paper discharge tray.

Next, a configuration and operation for detecting the paper length, which is a characteristic part of the present invention, will be described.
FIG. 1 is an explanatory diagram showing a configuration for detecting the length of paper fed from the manual paper feed mechanism unit 7.
In the present embodiment, the manual paper feed tray 32 of the manual paper feed mechanism unit 7 can set a plurality of sizes of paper having different lengths. The manual sheet feed mechanism unit 7 detects a trailing edge detection device that detects that the trailing edge of the sheet S fed by the pickup roller 34a and the separation roller pair 34b has passed a predetermined trailing edge detection position P1 in the manual sheet feeding tray 32. 60 part.

FIG. 5 is a perspective view showing a configuration of the rear end detection device 60.
The rear end detection device 60 includes a detection roller 61 that is a rotating body, a guide plate 62 that guides both end regions of the rotation shaft 61a of the detection roller 61 so that the detection roller 61 can be displaced up and down in the direction of gravity, and rotation. The detection unit is composed of a disc scale 63 provided at one end of the shaft 61a, a reflective optical sensor 64 for detecting the scale of the disc scale 63, and a control unit described later. The detection unit is provided in the manual sheet feeding mechanism unit 7, and the control unit is provided on the copier body side. The detection roller 61 is rotatable, and can be displaced downward in the direction of gravity by its own weight along the guide groove 62a of the guide plate 62. Since the guide groove 62a in this embodiment is a groove parallel to the paper stacking direction on the manual paper feed tray 32 (the normal direction of the bottom surface of the manual paper feed tray), the detection roller 61 has a bottom surface of the manual paper feed tray by its own weight. It is comprised so that it can displace toward. One sheet S is set between the detection roller 61 and the bottom surface of the manual feed tray 32, or a plurality of sheets are set in a stacked state. Therefore, the detection roller 61 comes into contact with the surface of the paper in a state where the paper located at the uppermost part of the paper set on the manual paper feed tray 32 is pressed by its own weight.

  A radial black-and-white pattern is formed on the disk surface of the disk-shaped scale 63, and the white and black pattern portions alternately pass through the detection area of the reflective optical sensor 64 by rotating the disk-shaped scale 63. It has become. As a result, the reflective optical sensor 64 outputs an output signal (rotation signal) in which the ON signal and the OFF signal are alternately repeated when the disc scale 63 is rotating, and the disc scale 63 is rotated. When the motor is stopped, an output signal (stop signal) consisting of only one of the ON signal and the OFF signal is output.

  When the uppermost sheet S among the sheets set on the manual sheet feeding tray 32 is sent out by the pickup roller 34a and the separation roller pair 34b, the detection of being in contact with the surface as the sheet S moves. The roller 61 rotates. Thereby, the disk-shaped scale 63 is also rotated, and an output signal (rotation signal) in which the ON signal and the OFF signal are alternately repeated is output from the reflective optical sensor 64. Thereafter, when the trailing edge of the sheet S passes through the contact position (rear edge detection position P1) with the detection roller 61, the detection roller 61 comes into contact with the surface of the sheet positioned immediately below the sheet S. Since this sheet is not moved, the rotation of the detection roller 61 stops when the rear end of the uppermost sheet S passes the rear end detection position P1. Thereby, the rotation of the disk-shaped scale 63 is also stopped, and a stop signal is output from the reflective optical sensor 64. By obtaining such an output signal from the reflective optical sensor 64, it is possible to detect that the trailing edge of the paper S has passed the trailing edge detection position P1.

  Note that detection means for detecting that the trailing edge of the sheet S sent out from the manual sheet feeding tray 32 has passed the trailing edge detection position P1 in the manual sheet feeding tray 32 is limited to such a trailing edge detection device 60. It does not have to be anything. For example, instead of the disk-shaped scale 63, a disk-shaped slit plate in which a radial slit is formed may be provided, and the slit of the disk-shaped slit plate may be detected by a transmission optical sensor. In addition, for example, an imaging unit that captures an image of the trailing edge detection position P1 may be provided to recognize that the trailing edge of the paper S has passed.

FIG. 6 is a control block diagram of the rear end detection device 60.
The control unit 65 comprehensively controls each part of the copying machine, and receives the output signal from the reflective optical sensor 64 and recognizes the length of the paper S based on the output signal. Do. The control unit 65 also supplies a paper feed driving device 66 for driving the pickup roller 34a and the separation roller pair 34b, a registration driving device 67 for driving the registration roller pair 11, paper size information for each paper feed tray, and the like. It is also connected to a storage unit 68 for storing, a registration sensor 69 arranged near the upstream side of the registration roller pair 11 in the sheet conveyance direction, for detecting the presence or absence of sheets, a timer for measuring time, and the like.

FIG. 7 is a flowchart showing a flow of control in paper conveyance. This flowchart will be described by taking as an example a case where image formation is performed on a sheet set on the manual feed tray 32.
When image formation is performed on the paper set on the manual paper feed tray 32, the user first sets the paper S on the manual paper feed tray 32 and then operates the operation panel provided on the copying machine main body. The size of the paper S set on the manual paper feed tray 32 is input. The input paper size information is temporarily stored in the storage unit 68. When the user presses the copy start button after setting the document on the scanner unit, an image forming command is input to the control unit 65.

  When the control unit 65 receives the image forming command, the control unit 65 starts an image forming process such as starting to drive the photosensitive member 12. At this time, the control unit 65 outputs a drive command to the paper feed driving device 66 to drive the pickup roller 34a and the separation roller pair 34b, and starts feeding the paper S on the manual paper feed tray 32 ( S1). Further, the control unit 65 outputs a timing start command to the timer 70 along with the output of the driving command to the paper feed driving device 66. Thereby, the timer 70 starts time measurement (S2). When feeding of the sheet S is started, the detection roller 61 rotates and a rotation signal is output from the reflection type optical sensor 64, and then the reflection type optical sensor 64 when the trailing end of the sheet S passes the trailing end detection position P1. Outputs a stop signal. Receiving this stop signal, the control unit 65 determines that the trailing edge of the sheet S has passed the trailing edge detection position P1 (S3), and the trailing edge of the trailing edge from the timing of the timer 70, that is, from the start of feeding the sheet S, is determined. The elapsed time (rear end passage time) t until the end detection position P1 is passed is temporarily stored in the storage unit 68 (S4). Then, the control unit 65 calculates the paper length based on the trailing edge passage time t (S5).

Here, a paper length calculation method in the present embodiment will be described.
As shown in FIG. 1, when the length of the paper S set in the manual paper feed tray 32 is L, the paper length L is calculated between the leading edge position P2 and the trailing edge detection position P1 of the paper S before feeding. And the sheet conveyance path length L2 between the trailing edge detection position P1 and the trailing edge position P3 of the sheet S before feeding. In the present embodiment, the trailing edge detection position P <b> 1 with which the detection roller 61 comes into contact is when the paper having the smallest paper length among the paper sizes that can be set in the manual paper feed tray 32 is set in the manual paper feed tray 32. However, it is fixedly disposed in the manual paper feed tray 32 so as to be located downstream of the rear end position of the paper in the paper feeding direction. Therefore, the paper conveyance path length L1 is constant regardless of the paper size set in the manual paper feed tray 32. On the other hand, the paper transport path length L2 changes according to the length of the paper S set in the manual paper feed tray 32. The sheet conveyance path length L2 can be obtained from V × t, where V is the conveyance speed of the fed sheet. The sheet conveyance speed V is constant at a predetermined speed immediately after the sheet feeding is started, and the trailing edge passage time t is measured by the timer 70 as described above. Therefore, the control unit 65 can calculate the paper conveyance path length L2 when it receives the trailing edge passage time t from the timer 70, and adds this paper conveyance path length L2 to the previously known paper conveyance path length L1. Thus, the length L of the fed paper S can be calculated.

In this embodiment, the rear end detection position P1 is fixed. However, the rear end detection position P1 is provided to move the detection roller 61 along the sheet conveyance direction, for example. The detection position P1 may be configured to be changed in the manual feed tray 32 along the paper conveyance direction. Examples of the detection position changing means in this case include a means for the user to manually slide the detection roller 61 along the paper conveyance direction. When the rear end detection position P1 can be changed as described above, the sheet conveyance path length L2 changes according to the change. However, since the sheet conveyance path length L2 after the change of the trailing edge detection position P1 can be easily grasped, the sheet length can be calculated by the same method as in the case where the trailing edge detection position P1 has a fixed configuration.
In this embodiment, the rear end detection position P1 is fixed. However, for example, the rear end detection position P1 is set to the manual feed tray by providing a plurality of detection rollers 61 along the sheet conveyance direction. It is also possible to have a configuration in which a plurality of units 32 exist along the sheet conveyance direction. In this configuration, the passage of the trailing edge of the sheet is detected at any one of the plurality of trailing edge detection positions P1, and the sheet length is calculated in the same manner as in the case where the trailing edge detection position P1 has a fixed configuration. it can.

  In this embodiment, the trailing edge passage time t, which is the elapsed time from when the paper S starts to be fed until the trailing edge thereof passes the trailing edge detection position P1, is counted, and based on the trailing edge passage time t. Although the method for calculating the length L of the paper S has been described, other methods may be used. For example, the following calculation method may be used.

FIG. 8 is an explanatory diagram for explaining another method for detecting the length of a sheet fed from the manual sheet feeding mechanism unit 7.
Assuming that the length of the paper S set in the manual paper feed tray 32 is L, the paper length L is the paper conveyance path between the detection position (leading edge detection position) P4 of the registration sensor 69 and the trailing edge detection position P1. The length L3 can also be calculated by subtracting the sheet conveyance path length L4 between the leading edge position P5 and the leading edge detection position P4 of the sheet S when the trailing edge of the sheet S reaches the trailing edge detection position P1. it can. The paper transport path length L3 is constant regardless of the paper size set in the manual paper feed tray 32. On the other hand, the paper conveyance path length L4 changes according to the length of the paper S set in the manual paper feed tray 32. The sheet transport path length L4 is obtained by measuring the time t ′ from when the trailing edge of the sheet S passes the trailing edge detection position P1 to when the leading edge of the sheet S is detected by the registration sensor 69. It can be obtained from t ′. The time t ′ can be easily measured by using the timer 70 as described above. According to this calculation method, the control unit 65 can calculate the sheet conveyance path length L4 when the leading edge of the sheet S is detected by the registration sensor 69, and the sheet conveyance path length L1 can be calculated in advance from the sheet conveyance path length L1. By subtracting the length L4, the length L of the fed paper S can be calculated.

Immediately after the start of paper feeding, the paper conveyance speed is unstable due to slippage between the pickup roller 34a and the paper S and separation operation by the separation roller pair 34b. In the calculation method described with reference to FIG. 1, since an unstable paper conveyance speed immediately after the start of paper feeding is estimated to be constant and the paper length L is calculated, some errors are included. On the other hand, in the calculation method described with reference to FIG. 8, the error is small because the unstable sheet conveyance speed immediately after the start of sheet feeding does not affect the calculation result of the sheet length L. However, in the calculation method described in FIG. 8, the calculation timing of the paper length L may be delayed compared to the calculation method described in FIG.
In the calculation method described with reference to FIG. 8, the length L of the paper S set on the manual paper feed tray 32 has a trailing edge at the trailing edge detection position P <b> 1 before the leading edge passes through the registration sensor 69. However, the same applies to the case where the trailing edge passes through the registration sensor 69 and the trailing edge passes through the trailing edge detection position P1. Can think.

  After calculating the length L of the paper fed as described above, the control unit 65 reads the paper size information of the manual paper feed tray 32 input by the user from the storage unit 68, and the paper length related to this paper size information. It is determined whether or not the calculated paper length L matches (S6). In this determination, it is not necessary to completely match, and it is determined that they match if they are within an allowable range determined by the process using the paper length information. If it is determined that they do not match in this determination (No in S6), the control unit 65 uses the paper size information of the manual paper feed tray 32 stored in the storage unit 68 according to the calculated paper length. (S7), a warning message indicating that the paper size information of the manual paper feed tray 32 is incorrect is displayed on the operation panel and other display means provided in the copying machine main body (S7). S8). If the user can be notified that the paper size information of the manual paper feed tray 32 is incorrect, the user may be notified by a method other than displaying a warning message. When the copying machine is connected to an external device such as a personal computer (PC), the warning message may be displayed on the display unit of the external device. If it is determined in the above determination (Yes in S6), the paper size information of the manual paper feed tray 32 input by the user is used in the subsequent processing using the paper length.

  When the leading edge of the fed paper S is detected by the registration sensor 69 (S9), the control unit 65 outputs a drive stop command to the paper feed driving device 66 to drive the pickup roller 34a and the separation roller pair 34b. Is stopped (S10). As a result, the sheet S is stopped in a state where the leading edge of the sheet S hits the registration roller pair 11. Thereafter, the control unit 65 outputs a drive command to the registration driving device 67 so that the registration roller pair 11 is driven at the timing when the toner image on the photoconductor 12 enters the transfer unit (S11). ).

  Thereafter, the control unit 65 will pass the detection position of the registration sensor 69 if the sheet has the sheet length related to the sheet size information of the manual sheet feed tray 32 stored in the storage unit 68. Even after the time has come (S13), when the registration sensor 69 detects the paper S (Yes in S14), the control unit 65 determines that a jam has occurred and performs jam processing (S15). Specifically, for example, the image forming operation is stopped, and a warning that a jam has occurred or a warning that prompts the user to restore the jam is notified. On the other hand, if the registration sensor 69 has not detected the sheet S after the time has come (No in S14), the control unit 65 outputs a drive stop command to the registration driving device 67 to drive the registration roller pair 11. Is stopped (S16).

  Here, the sheet S having a length longer than the sheet length related to the sheet size information of the manual sheet feed tray 32 stored in the storage unit 68 is actually caused by a user input error or forgetting to input. There may be a situation where paper is fed. In this case, if the jam processing determination is performed according to the paper size information (S13, S14), the user sets the paper S of an appropriate size in the manual paper feed tray 32 and the paper is appropriately transported. Regardless, there arises a problem that jam processing is performed by judging that a jam has occurred. According to the present embodiment, even when a sheet S having a length longer than the sheet length according to the sheet size information in the storage unit 68 is actually fed, the length of the sheet S is set to an early stage after feeding. At this stage, the jam processing determination is made based on the grasped sheet length, so that such a problem does not occur.

  In addition, due to a user's input mistake or forgetting to input, the paper S having a length shorter than the paper length related to the paper size information of the manual paper feed tray 32 stored in the storage unit 68 is actually supplied. There may be a situation where paper is used. In this case, when an image forming operation is performed based on the paper size information, the toner image on the photoconductor 12 continues to carry the paper S that does not carry the paper S even after the trailing edge of the paper S passes the transfer unit. It is transferred onto the surface of the belt 47. Therefore, as a result of a large amount of toner adhering to the paper transport belt 47, there arises a problem that if the toner cannot be removed sufficiently, the back surface of the paper is stained with toner. According to the present embodiment, even when a sheet S having a length shorter than the sheet length related to the sheet size information in the storage unit 68 is actually fed, the length of the sheet S is set to an early stage after feeding. Thus, it is possible to stop the image forming operation before the trailing edge of the sheet S passes through the transfer portion. It should be noted that the image forming operation may be stopped when it is determined that the sheet S having a shorter length than the sheet length related to the sheet size information in the storage unit 68 is actually fed. However, since the size of the paper S set by the user in the manual paper feed tray 32 is normally an appropriate size intended by the user, the toner image until the trailing edge of the paper S passes through the transfer portion. Forms an image on the photoconductor 12 and transfers the image onto the paper S. A toner image to be transferred after the trailing edge of the paper S passes through the transfer portion is not imaged on the photoconductor 12. It is better to do so.

  Since the length of the sheet S actually conveyed can be grasped as in the present embodiment, the sheet size information input by the user needs to be stored in the storage unit 68 in advance in order to solve the above-described problem. There is no. However, the paper size information stored in the storage unit 68 in advance by user input is often used for other processing in the copying machine and cannot be omitted. As described above, a warning message is issued when the paper length related to the paper size information stored in the storage unit 68 is different from the length of the paper set in the manual paper feed tray 32, so that the user can make an appropriate response. Input of paper size information can be prompted, and appropriate control can be performed in the other processes described above. In this embodiment, since the length of the paper set in the manual paper feed tray 32 cannot be grasped unless the fed paper S is conveyed, the paper is set in the manual paper feed tray 32 before feeding. When processing using the paper size is performed before paper feeding, it is also necessary to store paper size information in the storage unit 68 in advance.

  In this embodiment, when setting paper in the manual paper feed tray 32, the user slides the paper between the bottom surface of the manual paper feed tray 32 and the detection roller 61 along the paper conveyance direction. set. When the paper set in the manual paper feed tray 32 is taken out, the paper sandwiched between the bottom surface of the manual paper feed tray 32 and the detection roller 61 is taken out by being pulled out along the paper transport direction. It is conceivable that the detection roller 61 gets in the way when such a sheet is set and taken out. Therefore, as shown in FIGS. 9A and 9B, when the paper S is set on the manual feed tray 32 at a position where the detection roller 61, which is a facing member, faces the upper surface of the paper S, and the opposing surface. You may comprise so that the detection roller 61 can move between the retracted positions which do not interfere with a paper set rather than the case where the detection roller 61 exists in an opposing position.

More specifically, as shown in FIGS. 9A and 9B, a dustproof cover 80 that covers the upper portion of the manual paper feed tray 32 is attached to the manual paper feed tray 32 so as to be openable and closable. The dust cover 80 is configured such that the cover portion 81 is rotatable about the opening / closing shaft 82 as a rotation center. The cover portion 81 of the dustproof cover 80 has a wall portion (not shown) that faces a paper side portion (an end portion positioned in the front-rear direction in the figure) in a direction orthogonal to the paper transport direction. In these wall portions, when the dust-proof cover 80 is closed with respect to the manual paper feed tray 32, the detection rollers 61 can be displaced up and down in the gravity direction in both end regions of the rotation shaft 61a of the detection rollers 61. A long hole for guiding is provided, and the rotation shaft 61a of the detection roller 61 is supported by the long hole. With this configuration, when the dust cover 80 is closed as shown in FIG. 9A, the detection roller 61 is placed on the top of the manual feed tray 32 as in the case of the above-described embodiment. In a state where the sheet S positioned at the position is pressed by its own weight, the sheet S comes into contact with the surface of the sheet. When the dust cover 80 is closed as shown in FIG. 9A, a disk-like scale 63 provided at one end of the rotation shaft 61a of the detection roller 61 is provided as a reflection type (not shown) provided in the manual feed tray 32. It is set in the detection area of the optical sensor 64. On the other hand, when setting paper in the manual paper feed tray 32 or taking out paper from the manual paper feed tray 32, the dust cover 80 is opened as shown in FIG. As a result, the detection roller 61 provided on the dustproof cover 80 moves to a retracted position away from the paper S, and does not interfere with the work of setting or removing the paper.
Here, an example in which the dustproof cover 80 is used as the moving means for moving the detection roller 61 to the retracted position has been described, but the detection roller 61 is moved to the retracted position by other moving means without providing the dustproof cover 80. It is good also as a structure.

As described above, the copying machine that is the image forming apparatus of the present embodiment is an image forming apparatus that forms an image on the sheet S that is a recording material fed from the manual sheet feeding mechanism unit 7 that is a feeding apparatus. The manual paper feed mechanism unit 7 feeds the paper S one by one from the manual paper feed tray 32 as a recording material setting unit that can set a plurality of sizes of paper S having different paper lengths. Pickup roller 34a as the feeding means, and trailing edge detection as detection means for detecting that the trailing edge of the sheet S sent out by the pickup roller 34a etc. has passed a predetermined trailing edge detection position P1 in the manual paper feed tray 32. And a detection unit of the device 60. Further, in the copying machine main body, after the pickup roller 34a and the like send out the paper S, processing according to the length of the paper S sent out by the pickup roller 34a and the like based on the detection result of the detection unit of the trailing edge detection device 60. It has a control unit 65 as processing means for performing (jam processing or the like). With this configuration, as described above, the length of the sheet S that is actually fed can be grasped at an early stage after the sheet feeding. As a result, the control unit 65 can perform an appropriate process according to the length of the sheet S actually fed.
Further, as described above, the length of the paper set in the manual paper feed tray 32 can be obtained by providing detection position changing means for changing the trailing edge detection position P1 in the manual paper feed tray 32 along the paper conveyance direction. The rear end detection position P1 can be installed at an appropriate position according to the above. That is, the closer the trailing edge detection position P1 is to the trailing edge of the paper set in the manual paper feed tray 32, the earlier the paper length can be grasped. However, if the trailing edge detection position P1 is positioned upstream of the trailing edge of the paper set in the manual paper feed tray 32, the trailing edge detection position P1 is fixed. With this configuration, the trailing edge detection position P1 needs to be arranged near the downstream side in the sheet transport direction from the trailing edge of the sheet having the minimum sheet length among the sheet sizes that can be set in the manual feed tray 32. Comes out. In this case, when a paper having the maximum paper length among the paper sizes that can be set in the manual paper feed tray 32 is set in the manual paper feed tray 32, the trailing edge of the paper is changed after the paper feeding operation is started. There may be a case where it takes time to pass the trailing edge detection position P1 and it is difficult to quickly grasp the sheet length. On the other hand, according to the configuration provided with the detection position changing means, the trailing edge detection position P1 is set near the downstream side in the sheet conveyance direction from the trailing edge in accordance with the size of the paper set in the manual paper feed tray 32. It becomes possible to do. As a result, it is possible to quickly grasp the paper length regardless of the size of paper set in the manual paper feed tray 32.
Further, as described above, a plurality of trailing edge detection positions P1 may exist in the manual feed tray 32 along the sheet conveyance direction. In this configuration, if the length of the paper is grasped by using the result of detecting the passage of the paper trailing edge first among the plurality of trailing edge detection positions P1, what kind of paper is fed to the manual paper feed tray 32? Even when a sized sheet is set, the sheet length can be quickly grasped.
In the present embodiment, the sheet S positioned at the top of the plurality of sheets set in the stacked state on the manual feed tray 32 by the pickup roller 34a or the like is sent out, and is detected by the trailing edge detection device 60. The section includes a detection roller 61 that is a rotating body that contacts the upper surface of the sheet S and can rotate as the sheet S moves, and a disk as a rotation stop detection unit that detects the rotation stop of the detection roller 61. And the reflective optical sensor 64 detects that the trailing edge of the paper S has passed the trailing edge detection position P1 when the reflective optical sensor 64 detects that the detection roller 61 has stopped rotating. is there. Thereby, it is possible to detect that the trailing edge of the sheet S has passed the trailing edge detection position P1 with a simple configuration.
In the present embodiment, the pickup roller 34a or the like feeds the uppermost sheet S positioned at the uppermost part among the plurality of sheets S set in the stacked state on the manual sheet feeding tray 32. The detection unit of the edge detection device 60 detects that the trailing edge of the sheet S has passed the trailing edge detection position P1 by using a detection roller 61 as an opposing member facing the upper surface of the uppermost sheet S. is there. In such a configuration, the detection roller 61 is opposed to the upper surface of the uppermost sheet S, and the case where the detection roller 61 is present at the opposite position when the sheet S is set on the manual paper feed tray 32. If a dustproof cover 80 is provided as a moving means for moving the detection roller 61 between the retraction position that does not interfere with the setting, the workability of setting and taking out the paper from the manual feed tray 32 can be improved. it can.
In particular, a detection roller 61 is attached to a dustproof cover 80 that can be opened and closed to cover an opening provided in the manual paper feed tray 32 in order to set the paper S in the manual paper feed tray 32, and this dustproof cover 80 is used as a moving means. By using it, it is not necessary to provide a dedicated moving means.
Further, in the present embodiment, the control unit 65 performs jam processing or the like based on the elapsed time t from the start of feeding of the pickup roller 34a or the like until the trailing end is detected by the detecting unit of the trailing end detection device 60. Thereby, when the detection unit of the trailing edge detection device 60 detects the passage of the trailing edge of the sheet S, in other words, at the stage before the sheet S is conveyed by the length of the sheet S or the sheet. The length of the paper S can be grasped at a stage before the trailing edge of S comes out of the manual paper feed tray 32. Therefore, the length of the paper can be grasped more quickly.
Further, in the present embodiment, the storage unit 68 is provided as a storage unit that stores size information including the length in the sheet conveyance direction of the sheet S set on the manual sheet feed tray 32, and the control unit 65 includes the pickup roller 34a. After the paper S is sent out, the paper length included in the size information stored in the storage unit 68 is compared with the paper length grasped based on the detection result of the detection unit of the trailing edge detection device 60. If they match, jam processing or the like is performed according to the former paper length, and if both do not match, jam processing or the like is performed according to the latter paper length. Thus, the above-described various problems can be solved without making a significant change to the existing control that performs jam processing or the like according to the sheet length included in the size information stored in the storage unit 68.
In the present embodiment, an operation panel as input means for inputting size information including the paper length of the paper S set in the manual paper feed tray 32, and storage means for storing the size information input to the operation panel. The control unit 65 includes a sheet length included in the size information stored in the storage unit 68 and the trailing edge detection device 60 after the pickup roller 34a or the like sends out the sheet S. In order to notify that the size information input to the operation panel is incorrect when both do not match, a warning message is displayed. The notification process to be displayed is performed. As a result, the user can recognize that the size information input to the operation panel is incorrect, and can prompt the user to input appropriate size information.
Further, in this embodiment, the case where the length of the paper S set on the manual paper feed tray 32 is detected has been described. However, if the detection unit of the trailing edge detection device 60 is also provided in the paper feed cassette 51, the paper is fed. The length of the paper set in the cassette 51 can be similarly detected.
Further, in the present embodiment, the control unit 65 causes the rear side of the sheet S having the sheet length grasped based on the detection result of the detection unit of the trailing edge detection device 60 after the pickup roller 34a or the like sends out the sheet S. A process of stopping the image forming operation is performed before the image forming of the image formed on the rear side in the paper transport direction from the edge is started. Thus, even when a sheet S having a length shorter than the sheet length related to the sheet size information of the manual sheet feed tray 32 stored in the storage unit 68 is actually fed, the trailing edge of the sheet S is It is possible to prevent the toner image on the photoreceptor 12 from being transferred to the surface of the paper transport belt 47 after passing through the transfer portion.
In the present embodiment, as described with reference to FIG. 8, the registration sensor 69 is provided as another detection means for detecting that the leading edge of the sheet S sent out by the pickup roller 34a or the like has passed the predetermined detection position P4. Then, after the pickup roller 34a or the like has fed out the paper S, the control unit 65 may perform jam processing or the like based on the detection result of the detection unit of the trailing edge detection device 60 and the detection result of the registration sensor 69. Good. In this case, since the unstable paper conveyance speed immediately after the start of paper feeding does not affect the calculation result of the paper length L, there is little error in the calculation result of the paper length L, and the paper length L can be grasped more accurately.

FIG. 3 is an explanatory diagram illustrating a configuration for detecting the length of a sheet fed from a manual sheet feeding mechanism unit of the copier according to the embodiment. FIG. 2 is a longitudinal front view showing an outline of the internal structure of the copier. FIG. 4 is an enlarged longitudinal front view showing the manual sheet feeding mechanism. FIG. 3 is an exploded perspective view showing a part of the manual sheet feeding mechanism. The perspective view which shows the structure of a rear-end detection apparatus. The control block diagram of the rear end detection apparatus. 6 is a flowchart showing a flow of control in paper conveyance. FIG. 6 is an explanatory diagram for explaining another method for detecting the length of a sheet fed from the manual sheet feeding mechanism. (A) is explanatory drawing which shows the state which closed the dust-proof cover provided in the manual paper-feed mechanism part. (B) is explanatory drawing which shows the state which the dustproof cover opened.

Explanation of symbols

2 Printer Engine 3 Cassette Feeding Mechanism Unit 6 Paper Reversing Mechanism Unit 7 Manual Feeding Mechanism Unit 11 Registration Roller Pair 12 Photoconductor 32 Manual Feeding Tray 34a Pickup Roller 34b Separating Roller Pair 47 Paper Conveying Belt 51 Paper Feeding Cassette 60 Rear End Detection device 61 Detection roller 62 Guide plate 62a Guide groove 63 Disc scale 64 Reflective optical sensor 65 Control unit 66 Paper feed drive device 67 Resist drive device 68 Storage unit 69 Resist sensor 70 Timer 80 Dust cover P1 Rear end detection position

Claims (14)

A recording material set unit capable of setting recording materials of a plurality of sizes having different lengths in the recording material conveyance direction;
In a feeding device having a feeding means for feeding recording materials one by one from the recording material set unit,
2. A feeding apparatus comprising: a detecting unit configured to detect that a trailing end of the recording material fed by the feeding unit has passed a predetermined trailing end detection position in the recording material setting unit. The feeding device according to claim 1,
2. A feeding apparatus according to claim 1, further comprising detection position changing means for changing the predetermined rear end detection position along the recording material conveyance direction in the recording material setting section. The feeding device according to claim 1,
A feeding apparatus comprising a plurality of the predetermined rear end detection positions in the recording material setting portion along a recording material conveyance direction. The feeding device according to claim 1, 2, or 3,
The sending means sends out the uppermost recording material located at the uppermost portion among the plurality of recording materials set in a stacked state in the recording material set portion,
The detection means includes a rotating body that contacts the upper surface of the uppermost recording material and can rotate as the recording material moves, and a rotation stop detection unit that detects a rotation stop of the rotating body, A feeding device, wherein the rotation stop detection unit detects that the rear end of the uppermost recording material has passed the predetermined rear end detection position when detecting the rotation stop of the rotating body. . In the feeding device according to claim 1, 2, 3, or 4,
The sending means sends out the uppermost recording material located at the uppermost portion among the plurality of recording materials set in a stacked state in the recording material set portion,
The detection means detects that the rear end of the uppermost recording material has passed the predetermined rear end detection position using a facing member that faces the upper surface of the uppermost recording material.
The facing position where the facing member faces the upper surface of the uppermost recording material, and the retraction which does not interfere with the setting when the recording material is set in the facing position when the recording material is set in the recording material setting portion. A feeding device comprising a moving means for moving the opposing member between positions. The feeding device according to claim 5, wherein
In order to set the recording material in the recording material set part, and having a dust cover that can be opened and closed to cover the opening provided in the recording material set part,
The dust-proof cover is used as the moving means by attaching the counter member to the dust-proof cover. When the dust-proof cover is closed, the counter member takes the counter position, and when the dust-proof cover is opened, the counter member Is a feeding device configured to take the retracted position. In an image forming apparatus that forms an image on a recording material fed from a feeding apparatus,
As the feeding device, using the feeding device of claim 1, 2, 3, 4, 5 or 6,
After the feeding means provided in the feeding device feeds the recording material, the recording material sent in the feeding device is sent in accordance with the length of the recording material in the recording material conveyance direction based on the detection result of the detecting means provided in the feeding device. An image forming apparatus comprising processing means for performing processing. The image forming apparatus according to claim 7.
The image forming apparatus according to claim 1, wherein the processing means performs the processing based on an elapsed time from the start of sending by the sending means to the time of detection by the detecting means. The image forming apparatus according to claim 7 or 8,
A storage unit that stores size information including a recording material conveyance direction length of the recording material set in the recording material setting unit included in the feeding device;
The processing means, after the sending means sends out the recording material, the recording material conveyance direction grasped based on the recording material conveyance direction length included in the size information stored in the storage means and the detection result of the detection means. When the two match, the above processing is performed according to the former recording material conveyance direction length, and when the two do not match, the latter recording material conveyance direction length is obtained. An image forming apparatus that performs the above processing in response. The image forming apparatus according to claim 7 or 8,
An input means for inputting size information including a recording material conveyance direction length of a recording material set in the recording material setting unit included in the feeding device;
Storage means for storing size information input to the input means,
The processing performed by the processing means is grasped based on the recording material conveyance direction length included in the size information stored in the storage means and the detection result of the detection means after the sending means sends out the recording material. And a recording material conveyance direction length, and a notification process for notifying that the size information input to the input means is incorrect when the two do not match. Image forming apparatus. The image forming apparatus according to claim 7, 8, 9 or 10.
The image forming apparatus, wherein the recording material setting unit included in the feeding device is a recording material setting unit for manual feeding. The image forming apparatus according to claim 7, 8, 9, 10 or 11.
An image forming apparatus comprising a plurality of the feeding devices. The image forming apparatus according to claim 7, 8, 9, 10, 11, or 12.
The processing performed by the processing means is performed in the recording material transport direction from the rear end of the recording material having a recording material transport direction length grasped based on the detection result of the detection means after the sending means sends out the recording material. An image forming apparatus characterized in that the image forming operation is stopped before image forming of an image formed on the rear side is started. The image forming apparatus according to claim 7, 8, 9, 10, 11, 12, or 13.
Another detecting means for detecting that at least one of the leading end and the trailing end of the recording material sent out by the sending means has passed a predetermined detection position;
An image forming apparatus according to claim 1, wherein the processing means performs the processing based on a detection result of the detection means and a detection result of the other detection means after the recording means has sent the recording material.

Images