JP4814066B2 - Sheet-like medium conveying apparatus, image forming apparatus, and sheet-like medium conveying method - Google Patents

Description

  The present invention relates to a sheet-like medium conveyance device that conveys a sheet-like medium (hereinafter, also referred to as paper) without damaging the double-feed, an image forming apparatus provided with the sheet-like medium conveyance means, and a sheet-like medium conveyance Regarding the method.

  Conventionally, printing machines, copiers, printers, and facsimiles are provided with double feed detection means for detecting double feed of paper. When a double feed is detected, the device is stopped as a jam or the presence of double feed paper is detected. Methods such as notifying the user with a tape marker have been taken.

  However, stopping the apparatus as a jam causes a decrease in productivity, and discards the multi-feed paper as jam paper, which wastes paper. Further, the operation of removing the multifeed paper from the discharged paper is troublesome for the user, and the paper is wasted by discarding the removed multifeed paper.

  When an image is formed on a multi-feed paper, the ink and toner constituting the image are also discarded together with the paper, and thus wasteful consumption occurs, and energy required for toner or image fixing is wastefully consumed. Particularly in a high-speed machine, the apparatus is large, so that the residual paper in the machine that must be removed and the energy consumption during re-operation are large, and the downtime has a great influence on the productivity reduction.

  There are the following known techniques for solving the double feed. The known technology includes an upstream sheet conveying means, a downstream sheet conveying means, a sheet polymerization detecting means provided between the upstream sheet conveying means and the downstream sheet conveying means, and the like. When transporting the sheet by driving the upstream sheet conveying means and the downstream sheet conveying means during conveyance, the driving of the upstream sheet conveying means is stopped when the superposition detection means detects the superposition (double feed) of the sheet. On the other hand, the driving of the downstream sheet conveying means is continued as it is. Then, only the previous sheet is conveyed while the subsequent sheet is stopped, and the polymerization is eventually eliminated. The polymerization detection means detects the elimination of the polymerization, and after a predetermined time, the driving of the upstream sheet conveying means that has been stopped is resumed (see, for example, Patent Document 1).

  However, in the technique disclosed in Patent Document 1, the downstream sheet conveying unit is in a driving state and the upstream sheet conveying unit is in a driving stop state at the time of double feed detection. In other words, it is conceivable that the overlapping portion of the sheets is positioned in the upstream sheet conveying means when the double feeding is detected. In such a case, the downstream side sheet conveying unit conveys the front side of the previous sheet positioned on the upstream side sheet conveying unit in the driving stopped state, and the downstream sheet conveying unit conveys the previous sheet. It is assumed that an excessive load is generated and the apparatus is stopped, or an excessive force is applied to the sheet to damage the sheet so that the double feed state cannot be smoothly eliminated.

JP 2004-323143 A

  SUMMARY An advantage of some aspects of the invention is that it provides a paper conveyance device, an image forming apparatus, and a paper conveyance method capable of eliminating double feeding without damaging a sheet-like medium.

In order to achieve the above-mentioned object, the invention according to claim 1 is a sheet-like medium being conveyed and arranged on the upstream side conveying means for conveying the sheet-like medium, downstream of the upstream-side conveying means in the conveying direction of the sheet-like medium. A double feed detecting means for detecting a double feed of the medium; a downstream transport means for transporting the sheet-like medium, disposed downstream of the double feed detecting means in the transport direction of the sheet-like medium; and the double feed detecting means Control means for controlling the stop of driving of the upstream conveying means on the basis of the output from the multi-feeding means that the sheet-like medium being conveyed is changed from the double feeding state to the single feeding state. Based on the detection by the detecting means, the conveyance of the sheet-like medium by the upstream conveying means is stopped.
According to a second aspect of the present invention, in the sheet-like medium conveyance device according to the first aspect, the control means includes a storage means for holding length information of a multi-feed portion of the conveyed sheet-like medium.
According to a third aspect of the present invention, an upstream side conveyance unit that conveys a sheet-like medium, and a downstream of the upstream side conveyance unit in the conveyance direction of the sheet-like medium, and detects double feeding of the sheet-like medium being conveyed. Based on the input from the double feed detection means, the downstream conveyance means for conveying the sheet-like medium, arranged downstream of the double feed detection means in the conveyance direction of the sheet-like medium, Control means for controlling the drive stop of the upstream conveying means, the control means being a single feed prior to the double feed detecting means detecting the double feed state of the preceding sheet-like medium and the succeeding sheet-like medium. The state conveyance length is measured, and the length obtained by subtracting the single-feed state conveyance length from the size information in the conveyance direction of the sheet-like medium is defined as the conveyance length of the double-feed state portion. Starting from the time when it passes through the side transport means. Until the elapsed time required to carry the double feed state transport length the both, and it stops the conveyance of the sheet-like medium by the upstream transport means.
According to a fourth aspect of the present invention, in the sheet-like medium conveyance device according to the third aspect, the control means includes a storage means for holding size information in the conveyance direction of the conveyed sheet-like medium. .
According to a fifth aspect of the present invention, in the sheet-like medium conveyance device according to any one of the first to fourth aspects, the upstream-side conveyance unit and the downstream-side conveyance unit each include a pair of opposed rollers, and a pair of rollers. One of them was a driving roller.
According to a sixth aspect of the present invention, in the sheet-like medium conveyance device according to any one of the first to fifth aspects, the control unit measures a conveyance length in a double-feed state, and at least determines the double-feed state conveyance length. For the corresponding time, the conveyance of the sheet-like medium by the upstream-side conveying means is stopped.
According to a seventh aspect of the present invention, in the sheet-like medium conveyance device according to any one of the first to sixth aspects, the double feed detection means is an optical detection means.
According to an eighth aspect of the present invention, in the sheet-like medium conveyance device according to any one of the first to seventh aspects, the double feed detection means is also used as another sensor provided in the conveyance system.
According to a ninth aspect of the present invention, in the sheet-like medium conveyance device according to any one of the first to eighth aspects, the downstream-side conveyance unit is a registration roller.
According to a tenth aspect of the present invention, in an image forming apparatus having a sheet medium conveying means, the sheet medium conveyance device according to any one of the first to ninth aspects is provided.
According to an eleventh aspect of the present invention, when the sheet-like medium is conveyed by being conveyed by the upstream conveying means and the downstream conveying means, the trailing edge of the preceding sheet-like medium and the trailing sheet-like medium are When the region of the double feed state conveyance length in a state where it overlaps the leading end portion passes through the upstream conveyance unit, the conveyance driving force by the upstream conveyance unit is stopped to convey the subsequent sheet-like medium. While stopping, the conveyance driving force by the downstream conveyance means is continuously applied, so that the preceding sheet-like medium is advanced while leaving the succeeding sheet-like medium to eliminate the double feed state.
According to a twelfth aspect of the present invention, in the sheet-like medium conveying method according to the eleventh aspect, when the double feeding state is eliminated, the conveyance of the succeeding sheet-like medium by the upstream-side conveying means is restored.
The invention according to claim 13 includes a conveying unit that conveys the sheet-like medium, and a multi-feed detecting unit that is arranged downstream of the conveying unit and detects a multi-feed of a plurality of sheet-like media being conveyed, The transporting means is stopped based on the fact that the double feed detecting means detects a decrease in the number of double feeds.
According to a fourteenth aspect of the present invention, in the sheet-like medium conveyance device according to the thirteenth aspect, the control unit measures and stores the conveyance length in the double feed state for each double feed number detected by the double feed detection unit, The conveying means is sequentially stopped for a time corresponding to the conveying length in the double feeding state.
According to a fifteenth aspect of the present invention, there is provided a conveying unit that conveys a sheet-like medium, a multi-feed detecting unit that is arranged downstream of the conveying unit and detects a multi-feed of a plurality of sheet-like media being conveyed, and a sheet to be conveyed A sheet-like medium transport device having sheet-like medium size storage means for storing and holding the size of the sheet-like medium and control means for controlling them, wherein the control means is provided for each number of multi-feeds detected by the double-feed detection means. It has a conveyance state length storage means for measuring and storing the conveyance length in the conveyance state, and obtained from the conveyance state length storage means from the length of the sheet medium obtained from the sheet medium storage means. The length obtained by reducing the transport length is defined as the transport length in the double feed state, and the time corresponding to the transport of the double feed state transport length after the trailing edge of the preceding sheet-shaped medium passes through the transport means, sequentially. The conveying means was stopped.
According to a sixteenth aspect of the present invention, in the sheet-like medium conveyance device according to any one of the thirteenth to fifteenth aspects, the double feed detection means is an optical detection means.
According to a seventeenth aspect of the present invention, in the sheet-like medium conveyance device according to any one of the thirteenth to fifteenth aspects, the double feed detection means can also be used as another sensor provided in the conveyance system.
According to an eighteenth aspect of the present invention, in the sheet-like medium conveying device according to any one of the thirteenth to fifteenth aspects, the second conveying means has a second conveying means downstream of the double feed detecting means, and the second conveying means is a registration roller. It was decided that.
The invention according to claim 19 includes image forming means for forming an image on the sheet-like medium conveyed by the sheet-like medium conveyance device according to any one of claims 13 to 15 and 18.

  According to the present invention, it is possible to provide a sheet-like medium conveying apparatus, an image forming apparatus, and a sheet conveying method that can eliminate double feeding without damaging the sheet-like medium.

[1] First Embodiment FIG. 1 is a schematic cross-sectional view of an image forming apparatus provided with a sheet-like medium conveyance device according to the present invention. In the following description, a sheet-like medium will be described as an example of a sheet-like medium. There is an image forming unit 200 substantially above the sheet conveying unit 100, and an image reading unit 300 above it.

  The paper transport unit 100 includes a paper tray 1 on which the paper S is stacked, a pickup roller 2a that feeds the paper S on the paper tray 1, a paper feed unit such as a feed roller 2b and a reverse roller 2c that separates the paper S, a transport roller 3, It consists of registration rollers 4a and 4b. The paper transport unit 100 is a component that transports the paper S delivered from the paper tray 1 toward the image forming unit 200.

  In the image forming unit 200, a plurality of pairs of rollers for transporting the paper S are arranged at an appropriate interval at which the paper can be transported. Since FIG. 1 is a schematic diagram, only the conveyance roller 3 and the registration rollers 4a and 4b are illustrated.

  When the paper feed signal is turned on, the pickup roller 2a rotates downward to feed out the paper S on the paper tray 1. The fed paper S is separated by one at the nip portion between the feed roller 2b and the reverse roller 2c and reaches the conveyance roller 3, and further conveyed and abutted against the nip portion of the registration roller 4 to correct the skew, thereby forming a drum shape. The toner image is sent out at a timely timing associated with the toner image on the photoreceptor 4.

  The image forming unit 200 includes a photoreceptor 4, a charging unit 5, a developing unit 6, a transfer unit 7, a cleaning unit 8, a conveyance belt 9 that conveys the sheet after image transfer, and a fixing device. 10 includes a writing unit 11 that partially exposes the uniformly charged photosensitive member 4 to form a latent image, and forms an image on the sheet S supplied from the sheet conveying unit 100, and a sheet discharge roller 12. Then, the paper is discharged to the paper discharge tray 13.

  FIG. 2 is a schematic diagram showing a part of the paper transport unit 100. The conveying roller 3 is upstream of the registration roller 4 in the conveying direction. The conveying roller 3 includes a driving roller 3a and a driven roller 3b. The registration roller 4 also includes a driving roller 4a and a driven roller 4b.

  Double feed detection means 15 is provided downstream of the transport roller 3 and upstream of the registration roller 4. The double feed detection means 15 is an optical detection means comprising a light emitting element 15a and a light receiving element 15b provided to face each other across a paper conveyance path formed between the guides 16 and 17. The detection output of the light receiving element 15b is input to the control means 20, and the drive and stop of the motor connected to the drive roller 3a is controlled by the output from the control means 20, and accordingly, the drive roller 3a is driven and stopped. The double feed detection means 15 can also be used as another sensor provided in the transport system.

  Similarly, the registration roller 4 is controlled to be driven and stopped by an output from the control means 20 such as a motor connected to the driving roller 4a, and the driving roller 4a is driven and stopped accordingly.

  The paper that has exited the transport roller 3 passes through the double feed detection means 15. The amount of light received by the light emitting element 11a from the light receiving element 11b varies depending on the presence or absence of the paper S passing between the light emitting element 15a and the light receiving element 15b, and the presence or absence of double feeding even when the paper S passes. Will also change. As shown in FIG. 3, the light receiving element output becomes the highest when there is no paper, and the light receiving element output becomes the smallest when single feeding, that is, single feeding is next, and when double feeding, these The presence or absence of double feeding can be determined from the difference in the degree of light attenuation. In addition, as will be described later, it is possible to detect the number of double feeds.

  In the transport roller 3, the sheet S sandwiched between the drive roller 3a and the driven roller 3b is transported downstream by the drive roller 3a that is rotated so as to be transportable in the transport direction. Hereinafter, the process of eliminating the double feed will be described with reference to FIG.

  In FIG. 4, the conveyance roller 3 is an upstream conveyance unit, and the registration roller 4 is a downstream conveyance unit. Double feed detection means 15 for detecting the double feed of the paper being transported is disposed at a position upstream of the registration roller 4 and downstream of the transport roller 3 in the paper transport direction.

Process 1:
In FIG. 4A, the paper is being conveyed in the double feed state from the upstream due to some factor. The leading edge of the following sheet (second sheet) S2 overlaps the trailing edge of the preceding sheet (first sheet) S1, and the leading edge of the preceding sheet S1 is held by the driving registration roller 4. A double feed portion is added to the driving conveyance roller 3. The double feed detection means 15 initially detects the absence of paper (output “no paper” in FIG. 3), and then detects the passage of only the preceding paper S1 (output “single paper” in FIG. 3). . In FIG. 4A, when the leading end of the multifeed portion passes through the multifeed detection means 15, double feed is detected by the output change of the multifeed detection means 15 (the output of “multifeed” in FIG. 3). ).

Process 2:
In FIG. 4B, the preceding paper S1 and the succeeding paper S2 advance downstream from the state of FIG. 4A while maintaining the double feed state, and accordingly, the rear end portion of the double feed portion. Is the moment when it passes through the double feed detecting means 15. In the course of this passage, the output of the double feed detection means 15 changes from the output at the time of “double feed” in FIG. 3 to the output at the time of “single feed”, so that the paper state changes from the double feed state to the single feed state. Detects that it has become (double feed end). The control means 20 captures this output change and stops the driving roller 3a constituting the conveying roller 3 at this time. At this time, since the rear end portion of the double feed portion passes through the double feed detection means 15, the double feed portion cannot exist on the transport roller 3 upstream of the double feed detection means 15. .

Accordingly, when the registration roller 4 is continuously driven, only the preceding sheet S1 advances downstream while leaving the trailing sheet S2.
Further, the control unit 20 calculates the time from the time of double feed detection in the process 1 to the end of double feed in the process 2 (multifeed state partial transport time), or this double feed state storage time and the paper transport speed. The double feed state conveyance length Lw is stored in the storage means as length information of the double feed portion.

Process 3:
In FIG. 4C, by continuing the driving of the registration roller 4 as it is, the preceding sheet S1 advances downstream leaving the succeeding sheet S2, and accordingly, the multifeed portion is reduced.

Process 4:
In FIG. 4D, the control unit 16 sets the drive resumption time of the transport roller 3 that has been stopped based on the length information of the double feed portion stored in the storage unit in the process 2, and at the drive resumption time. Then, the driving of the transport roller 3 is started and the transport of the succeeding paper S2 is resumed. This driving resumption time is at least the time when the double feed is canceled, and by adding an appropriate margin time, an appropriate interval is provided between the trailing edge of the preceding paper S1 and the leading edge of the succeeding paper S2. You can also.

  As described above, since the trailing sheet S2 is resumed after the trailing edge of the preceding sheet S1 has advanced before the leading edge of the trailing sheet S2, the double feed state is canceled. At this time, when it is necessary to temporarily stop the sheet by the registration roller 4 in order to match the timing of the image formation and the sheet, the stop time of the conveying roller 3 is set long and the interval between the preceding sheet S1 and the following sheet S2 is set. Although an interval may be provided, the double feed state is reliably canceled by stopping at least the double feed state conveyance length Lw.

  In addition, the multi-feed paper can be separated into one in the conveyance path, and the paper conveyance can be continued without stopping the apparatus, and a paper conveyance device with high productivity and reliability can be provided. Further, since there is no paper discarded due to double feeding, it is possible to provide a paper transport device that reduces wasteful consumption of paper resources and has a low environmental load.

[2] Second Embodiment Also in the second embodiment, an example in which the conveyance roller 3 is used as the upstream conveyance unit and the registration roller 4, the double feed detection unit 15, and the control unit 20 are used as the downstream conveyance unit shown in FIG. I will explain it. However, the control content by the control means 20 is different from that of the first embodiment.

  In the transport roller 3, the sheet S sandwiched between the drive roller 3a and the driven roller 3b is transported downstream by the drive roller 3a that is rotated so as to be transportable in the transport direction. Hereinafter, the process for eliminating the double feed will be described with reference to FIG. 5 and FIG. 6 describing the control contents of the control means 20.

Process 1:
It is the same as in the first embodiment that the double feed detection means 15 detects that the paper S has been conveyed in the double feed state. In the second embodiment, in FIG. 5A, prior to detecting double feed, the time detected as the single feed state of the preceding paper S1 (first paper) or the portion in the single feed state Is measured and stored as the single-feed state conveyance length.

  In FIG. 6, the control unit 20 waits for detection of the sheet by the double feed detection unit 15 (step P1), and when the leading edge of the preceding sheet S1 is detected, the past single-feed state conveyance length Ls stored in the storage unit. The value (the length that was in the single feed state when the preceding paper S1 passes through the portion of the double feed detection means 15) is reset (step P2). After the reset, the value of the single-feed state conveyance length Ls is added again over time (step P4). This addition is continued until the double feed detecting means 15 detects double feed. When double feed is detected (when it is determined YES in step P3), the detection time is stored in the recording means and the next step P5 is performed. Move on.

  In Step P5, as a precondition for stopping the driving of the conveying roller 3, the process waits for the trailing edge of the preceding sheet S1 to pass the conveying roller 3. If the driving of the conveying roller 3 is stopped before the trailing edge (multifeed portion) of the preceding sheet S1 passes through the conveying roller 3, the trailing edge of the preceding sheet S1 is caught in the nip portion of the conveying roller 3. This is because the preceding sheet S1 is pulled by the conveying force of the registration roller 4 in this state, so that the preceding sheet S1 is damaged and the driving source of the registration roller 4 is subjected to an excessive load.

  The control unit 20 has the size information of the preceding sheet S1 based on information stored in advance in the storage unit. For example, a paper detection sensor (not shown) provided in the paper tray 1 obtains the transport direction size information of the paper stored in the tray 1 and stores this size information in the storage means.

  Based on the leading edge detection time of the preceding sheet S1 already obtained in the process P1, the conveyance direction size information of the preceding sheet S1, and the distance (known) between the nip portion of the conveying roller 3 and the multifeed detecting means 15 The control means 20 can calculate the time when the rear end portion of S1 passes through the nip portion of the transport roller 3.

Process 2:
The control unit 20 determines that the trailing edge of the preceding sheet S1 has passed through the nip portion of the conveying roller 3, that is, the conveying roller 3 at the timing when the conveying roller 10 finishes feeding the first sheet by the length of the preceding sheet S1. Stop driving. This corresponds to step P6 in FIG. 5B and FIG.

Process 3:
Even if the driving of the conveying roller 3 is stopped, the driving of the registration roller 4 is continued, so that the preceding sheet S1 advances in the downstream direction, and thereby the trailing edge of the preceding sheet S1 exits the double feed detecting means 15. It is possible to separate the double feed by stopping the conveyance roller 3 from the front. The preceding sheet S1 is conveyed as it is to the image forming unit 200 by the registration roller 4 (FIG. 5C).

  During this time, the control unit 20 has the single-feed state conveyance length Ls of the preceding sheet S1 as known information in step P1, and the conveyance direction size of the preceding sheet S1, that is, the sheet length Lp is also known. Then, the double feed state transport length Lx is calculated by subtracting the single feed state transport length Ls from the paper length Lp (step P7), and the transport roller 10 is stopped in FIG. 5B. To wait for the preceding sheet S1 to be conveyed by the double feed state conveyance length Lx (steps P8 and P9).

Process 4:
When the preceding sheet S1 is conveyed by the double feed state conveying length Lx after the conveying roller 10 is stopped in FIG. 5B, the trailing edge of the preceding sheet S1 is the rear as shown in FIG. Since the entire area single-feed state does not overlap with the leading edge of the line paper S2, the conveyance roller 3 is restarted at this point and the conveyance of the subsequent sheet S2 is resumed (steps P9 and P10).

In the second embodiment, the transport roller 3 is stopped after the trailing edge of the preceding paper has passed the transport roller 3 serving as the upstream transport means, so that it is the downstream transport means without damaging the preceding paper S1. Since the double feed state is eliminated without causing the driving load of the registration roller 4 to be excessive, and the second sheet is resumed after the trailing edge of the preceding sheet S1 advances before the leading edge of the succeeding sheet S2. Then, along with the cancellation of the double feed state, the conveyance of the subsequent sheet S2 is resumed.
In addition, since the trailing sheet S2 can be stopped properly, separation of the double-fed sheets can be ensured, and the resumption of conveyance after the stop can be controlled appropriately. A highly reliable paper transport device can be provided. Further, since there is no paper discarded due to double feeding, it is possible to provide a paper transport device that reduces wasteful consumption of paper resources and has a low environmental load.

  In the first and second embodiments, the trailing edge of the preceding sheet S1 is conveyed when a conveyance driving force is applied to the sheet by the upstream conveyance unit (conveyance roller 3) and the downstream conveyance unit (registration roller 4). When the area of the double feed state conveyance length in a state where the leading edge of the subsequent sheet S2 overlaps the upstream conveyance unit, the conveyance driving force by the upstream conveyance unit is stopped to stop the rear A method of canceling the double feed state by stopping the conveyance of the line paper S2 and continuously applying the conveyance driving force by the downstream side conveyance means to leave the subsequent sheet S2 and advance the preceding sheet S1. It is embodied. When the multi-feed state is canceled, the conveyance of the succeeding paper S2 by the upstream-side transport unit is restored, so that the paper can be continuously transported after the multi-feed state is canceled.

  In the first and second embodiments, the conveyance unit is stopped at least for a time corresponding to the double-feed state conveyance length, so that the separation of the double-fed paper is further ensured, and the conveyance of the subsequent paper is also properly resumed. Since it becomes controllable, it is possible to provide a paper conveying apparatus with higher productivity and reliability. Further, since there is no paper discarded due to double feeding, it is possible to provide a paper transport device that reduces wasteful consumption of paper resources and has a low environmental load.

  In the first embodiment, the conveyance by the upstream conveying unit is stopped after detecting that the sheet being conveyed has changed from the double feeding state to the single feeding state, that is, the trailing edge of the double feeding portion is the double feeding detecting unit. Since the driving of the conveying roller 3 is stopped after passing through 15, it is desirable to arrange the double feed detecting means 15 as close as possible to the conveying roller 3. If the double feed detector 15 is disposed at a position away from the transport roller 3, the leading edge of the succeeding paper S2 is sandwiched between the registration rollers 4 when the double feed detector 15 detects the end of the double feed. Further, even if the conveying roller 3 is stopped, it becomes difficult to eliminate the double feed, and the paper may be pulled between the rollers, the paper may be damaged, or the driving source of the roller may be subjected to an excessive load. It is.

  On the other hand, in the second embodiment, the subsequent movement by the conveyance roller 3 is performed until at least the time required for conveyance of the multifeed portion has elapsed since the time when the trailing edge of the preceding sheet S1 has passed the conveyance roller 3. Since the conveyance of the sheet S2 is stopped, the succeeding sheet S2 is held by the conveyance roller 3 when the conveyance roller 3 is stopped. Therefore, the distance from the conveyance roller 3 to the double feed detection means 15 is long. However, it is possible to reliably eliminate the double feed state. Further, it is possible to separate the multi-feed by stopping the transport roller before the trailing edge of the preceding paper S1 passes through the multi-feed detection means 15.

  In the second embodiment, the stop time of the transport roller 3 may be set to be long so that a space is provided between the preceding sheet S1 and the succeeding sheet S2. However, the transport roller 3 stops at least at the double feed state transport length Lx. This is the same as in the first embodiment that the double feed state is reliably canceled.

  In each of the first and second embodiments, the conveyance roller 3 and the multifeed detection unit 15 are configured in the vicinity of the registration roller 4, but the present invention is not limited to this, and the sheet conveyance unit 100 is not limited thereto. It is also possible to apply a combination of a multi-feed detection means to an arbitrary conveyance roller arranged in the above.

  However, by disposing the paper transport device of the present invention immediately upstream of the registration roller 4, only one paper transport device is configured for paper transported from a plurality of paper feed units (paper tray 1). Since it is possible to eliminate double feeding, there is an advantage that the configuration is simple and an inexpensive apparatus can be realized.

  Further, as shown in FIG. 3, the double feed detection means 15 can also detect the absence of paper, so the measurement of the single feed state conveyance length Ls in the second embodiment and the preceding paper S1. Needless to say, it can be used as a trigger for measuring the timing of stopping the conveyance roller 3 when the trailing edge is missing, or a conveyance sensor for measuring the timing of conveyance control at an arbitrary position in the sheet conveyance path in the sheet conveyance unit 100 or when a jam occurs. It can also be used as a jam detection sensor for detecting the presence or absence of paper. In this case, there is no need to separately provide a conveyance sensor and a jam detection unit, so that there is an advantage that the configuration is simplified and an inexpensive apparatus can be realized.

  In addition to optical detection as in the present invention, the double feed detection means 15 is also known as a method of detecting by ultrasonic waves, a method of measuring the displacement of a roller that holds the paper, and the like. Needless to say, the same configuration can be realized in different methods. However, it is desirable to use optical means capable of obtaining high accuracy in order to measure the transport length. Also, in order to use the above-described conveyance sensor, optical detection is advantageous in terms of time required for detection and accuracy. If optical detection is used, it is possible to detect double feed status or single feed status with high accuracy, and control to separate multiple feeds can be performed with higher accuracy, so that a paper transport device with higher productivity and reliability can be obtained. Can be provided.

  The conveyance roller 3 can be stopped by excitation of a clutch brake or a drive motor. However, if the sheet can be stopped and held by an idling load, the sheet can be stopped only by stopping driving transmission by an electromagnetic clutch or the like. It may be configured.

  The unit of the increment / decrement counter for the single-feed state conveyance length Ls and the double-feed state conveyance length Lx in FIG. 6 is 1, but this shows the calculation concept, and the actual increment / decrement unit is the conveyance length in the calculation loop. It goes without saying that it is a unit or a time unit.

  According to the first and second exemplary embodiments, it is possible to prevent misprinting due to double feeding and to provide a highly productive and reliable apparatus with little downtime. Further, by reducing jams caused by double feeding, it is possible to provide an apparatus with high user operability by eliminating unnecessary jam handling operations. Furthermore, by preventing misprinting due to double feeding, wasteful consumption of paper can be reduced, and an apparatus with less environmental load can be provided.

  When the paper transport unit of the present invention is applied to an image forming apparatus, the multi-feed paper can be separated into one sheet in the transport path, so that the paper transport can be continued without stopping the apparatus, and the productivity is increased. In addition, a highly reliable image forming apparatus can be provided. In addition, because there is no paper discarded due to double feeding, it is possible to reduce wasteful consumption of paper resources and prevent wasteful consumption of ink, toner, and heat required for image formation. A forming apparatus can be provided. Especially in high-speed machines, it is large-sized, and there is a lot of energy consumed in the in-machine residual paper that must be removed and during re-operation. Also, downtime greatly affects productivity, so double feeding without stopping the equipment. The effect of avoiding this is also large economically.

[3] Third Embodiment The present embodiment relates to a paper conveying apparatus applicable to the image forming apparatus shown in FIG. In the third embodiment, as shown in FIG. 2, the conveyance roller 3 is provided as the upstream conveyance unit, the registration roller 4, the double feed detection unit 15, and the control unit 20 are provided as the downstream conveyance unit. A roller 30 is added. The contents of control by the control means 20 will be described later.

  In the paper conveying means shown in FIGS. 8 to 14, the double feed detecting means 15 is abbreviated, but as in FIG. 2, the light emitting element 15a and the light receiving element 15b are sandwiched across the paper conveying path, and light is emitted by the passing paper. Since the light from the element 15a is blocked and the amount of light received by the light receiving element 15b is attenuated, the presence / absence of double feeding and the number of sheets can be determined as shown in FIG.

  As shown in FIGS. 8 to 14, there is a pair of transport rollers 30 between the pair of registration rollers 4 and the pair of transport rollers 3 in the transport direction. The transport roller 3 and the transport roller 30 are configured to be able to transport a sheet sandwiched by a driving unit (not shown) in the transport direction. Further, the rotation is stopped by excitation of a known clutch brake or drive motor, and the sandwiched paper can be stopped.

Double feed cancellation:
The double feed canceling operation will be described with reference to FIGS. As shown in FIG. 8, the sheet is conveyed in the double feed state from some upstream due to some factor, and when the double feed unit reaches the double feed detection means 15, it is detected that the double feed has occurred. As shown in FIG. 9, the conveyance is continued as it is, and when the three-sheet multi-feed portion where the sheets further overlap each other reaches the multi-feed detection means 15, this further overlap is detected by the multi-feed detection means 15.

  Further, as shown in FIG. 10, when the trailing edge of the preceding first sheet passes through the double feed detection means 15, the double feed detection means 15 detects that the number of double feeds has decreased. To do. At this time, the conveyance roller 3 is stopped, and the second and subsequent sheets are held in a stopped state. Since the driving of the conveying roller 30 and the registration roller 4 is continued, as shown in FIG. 11, only the preceding first sheet is conveyed as it is toward the image forming unit 200 by the conveying roller 30 and the registration roller 4. The

  The control means 20 sets the time or conveyance length from FIG. 8 to FIG. 9 and further the time or conveyance length from FIG. 10 to the double feed state conveyance length Lw1 (the third sheet from the leading edge of the second sheet in the double feed state). And the double feed state conveyance length Lw2 (the length from the leading edge of the third sheet in the double feed state to the double feed state detection means 15 <the rear end of the first sheet>). Then, after the conveyance roller 3 is stopped in FIG. 10, it waits for the first sheet to be conveyed for the double feed state conveyance length (Lw1 + Lw2) (see FIG. 11).

  Thus, after the conveyance roller 3 is stopped in FIG. 10, if only the first sheet is conveyed for the double feed state conveyance length (Lw1 + Lw2), the driving of the conveyance roller 3 is resumed as shown in FIG. (Restart). As a result, the second and subsequent sheets of paper are resumed after the trailing edge of the first sheet has advanced before the leading edge of the second and subsequent sheets, so the double feed state of the first sheet is eliminated.

  At this time, when it is necessary to temporarily stop the sheet by the registration roller 4 for adjusting the timing of the image formation and the sheet, the stop time of the transport roller 3 is set to be long and the interval between the first sheet and the second sheet is set. However, the double feed state is reliably canceled by stopping at least the double feed state conveyance length (Lw1 + Lw2). Further, as shown in FIG. 13, the conveyance is continued, and the trailing edge of the second sheet deviates from the multifeed detection means 15, so that the multifeed detection means 15 detects that the number of multifeeds has decreased.

  At this time (when the trailing edge of the second sheet is removed from the double feed detection means 15), the transport roller 3 is stopped as shown in FIG. 13, and the third sheet is held. The conveyance roller 30 is in an idling (following) state so that the conveyance of the second sheet by the registration roller 4 is not hindered.

  From FIG. 12 to FIG. 13, the double feed state conveyance length Lw2 is added by the conveyance length in the meantime. In FIG. 13, after the conveyance roller 3 is stopped, the conveyance rollers 3 and 30 are driven again after waiting for conveyance for the double-feed state conveyance length Lw2 (see FIG. 14). As a result, the trailing edge of the second sheet moves ahead of the leading edge of the third sheet and the multi-feed is canceled, and then the transport of the third sheet is resumed. The Even when three or more double feeds are performed, it is possible to separate each by repeating the above movement.

Multifeed cancellation operation control procedure by the control means 20:
15 and 16 show a control flow by the control means. The subscript of the double feed state conveyance length Lw described in FIGS. 8 to 14 is represented by Lw [n] because it has an array structure in the flowchart. If the double feed detection means 15 detects an increase in paper in step SS2, the number of double feeds is counted in step SS3, and the double feed state conveyance length Lw is counted up in a loop from step SS6 to step SS5. ing.

  When the multifeed detecting means 15 determines in step SS6 that the multifeed number has decreased, the transport roller 3 is stopped in step SS7, and the trailing edge of the first sheet is the second and subsequent sheets in a loop from step SS11 to step SS10. The conveyance roller 30 is held stopped until it advances before the leading edge of the sheet. In step SS11, ΣLw [1 to n] represents the total sum of Lw [1] to Lw [n]. If the first sheet feed amount Lf exceeds the sum of the double feed state transport lengths, the trailing edge of the first sheet has advanced before the leading edge of the second and subsequent sheets.

  After restarting the driving of the conveying roller 10 in step SS12, the movement of Lw [n] and the subtraction of the number of double feeds are performed according to the elimination of one double feed sheet (step SS13, step). SS14). By repeating this until the number n of multi-feeds becomes 0 (step SS8), even a plurality of multi-feeds can be reliably separated and sent out one by one.

[4] Fourth Embodiment The present embodiment relates to a paper conveying apparatus applicable to the image forming apparatus shown in FIG. Also in the fourth embodiment, an example will be described in which the transport roller 3 is used as the upstream transport unit shown in FIGS. 8 to 14, the registration roller 4, the double feed detection unit 15, and the control unit 20 are used as the downstream transport unit. However, the contents of control by the control means 20 will be described below.

Double feed cancellation:
The double feed canceling operation will be described with reference to FIGS. 17 to 22 showing the configuration of the sheet conveying apparatus of this example. It is the same as in the third embodiment that the double feed detecting means 15 detects that the paper has been conveyed in the double feed state. In the fourth embodiment, in FIG. 17, prior to detecting double feeding, the single-feed state time or transport length of the first sheet is measured as the single-feed state transport length Ls 1, and the control means 20 Remember.

  As shown in FIG. 18, the transport roller 3 is stopped at the timing when the transport roller 3 finishes feeding the first sheet by the length of the sheet that can be known from the separately stored sheet size, and the second sheet is held. To do. This makes it possible to stop the transport roller 3 before the trailing edge of the first sheet passes through the multifeed detecting means 15 and separate the multifeed. The first sheet is directly conveyed to the image forming unit 200 via the registration roller 4 by the downstream conveying roller 30.

  The length obtained by subtracting the single-feed state conveyance length Ls1 from the sheet length Lp is referred to as a double-feed state conveyance length Lx1, and the double-feed state detection length Lx1 is conveyed after the conveyance roller 3 is stopped in FIG. After that, the driving of the conveying roller 3 is restarted (see FIG. 19). Thus, since the second sheet is resumed after the trailing edge of the first sheet has advanced before the leading edge of the second sheet, the double feed state is eliminated.

  In the third embodiment, it is desirable to arrange the double feed detection means 15 as close as possible to the conveyance roller 3. However, with the configuration of the fourth embodiment, the distance between the conveyance roller 3 and the double feed detection means 15 is large. However, the double feed state can be surely eliminated. Although the stop time of the transport roller 3 may be set long so that a gap is provided between the first sheet and the second sheet, the double feed state is stopped by stopping at least the double feed state transport length Lx1. It is the same as that of the said 3rd Embodiment that is eliminated reliably. When the double feed detecting means 15 detects the double feed again while continuing the conveyance, the conveyance length Ls2 of the second sheet conveyed so far is stored (see FIG. 20).

  As with the first sheet, the conveyance roller 3 is stopped at the timing when the conveyance roller 3 finishes feeding the second sheet as long as the sheet length can be known from the sheet size, and the third sheet is held (see FIG. 21). The second sheet is directly conveyed to the image forming unit 200 through the registration roller 4 by the downstream conveying roller 30.

  The length obtained by subtracting the single-feed state conveyance length Ls2 from the sheet length Lp is defined as a double-feed state conveyance length Lx2, and the double-feed state detection length Lx2 is conveyed after the conveyance roller 3 is stopped in FIG. Then, the driving of the conveying roller 3 is restarted (restarted) (see FIG. 22). As a result, since the third sheet is resumed after the trailing edge of the second sheet has advanced before the leading edge of the third sheet, the double-feed state of the second sheet is also eliminated.

Multifeed cancellation operation control procedure by the control means 20:
23 and 24 show the control flow of the fourth embodiment. The subscript of the double feed state conveyance length Ls described in FIG. 17 to FIG. 22 is represented by Ls [n] because it has an array structure in the flowchart. In step PS2, the number of multi-feed sheets is counted in step PS2 and n in step PS3, and the multi-feed state conveyance length Ls is counted up in a loop from step PS6 to step PS5.

  If it is determined in step PS6 that the trailing edge of the preceding sheet is missing, the conveyance roller 3 is stopped in step PS7, the double feed state detection length Lx is calculated in step PS10, and then the double feed state is detected in a loop from step PS12 to step PS11. By subtracting the length Lx, the conveyance roller 3 is held stopped until the trailing edge of the first sheet advances before the leading edge of the second and subsequent sheets.

  After restarting (restarting) the driving of the conveying roller 3 in Step PS13, the movement of Ls [n] corresponding to the number of double feeds is performed in Step PS14, and the process returns to Step PS2. After determining the trailing edge omission of the preceding paper in step PS6, the subtraction of the multifeed number is performed in step PS8, and the entire loop is repeated until the multifeed number n becomes 0 (step PS9). Even with double feeding, it can be separated and sent out reliably.

  In the fourth embodiment, an example in which the conveyance roller 3 and the double feed detection unit 15 are configured in the vicinity of the registration roller 4 is shown, but the present invention is not limited to this, and any conveyance roller included in the conveyance unit 103 may be used. Needless to say, this is applicable even if double feed detection is provided. However, by arranging it in the vicinity of the upstream of the registration roller 104, it is possible to obtain an operational effect by configuring only one sheet of paper conveyed from a plurality of paper feeding units, so that the configuration is simplified and an inexpensive apparatus can be realized. There are benefits.

  As shown in FIG. 3, the double feed detection 11 can also detect a state where there is no paper, so the single feed state conveyance length Ls in Example 2 is measured and the trailing edge of the first sheet is missing. Of course, it can be used as a trigger for measuring the timing to stop the conveyance roller 10, but it can also be used as a conveyance sensor for measuring the timing of conveyance control or as jam detection for detecting the presence or absence of paper when a jam occurs. In this case, there is no need to provide a separate conveyance sensor and jam detection means, so that there is an advantage that the configuration is simplified and an inexpensive apparatus can be realized.

  In addition to optical detection as in the present invention, the double feed detection means is also known to be a method of detecting by ultrasonic waves, a method of measuring the displacement of a roller that sandwiches the paper, etc. It goes without saying that the same configuration can be established in different methods. However, it is desirable to use optical means capable of obtaining high accuracy in order to measure the transport length. Also, in order to use the above-described conveyance sensor, optical detection is advantageous in terms of time required for detection and accuracy.

  The conveyance roller 10 can be stopped by excitation of a clutch brake or a drive motor. However, if the sheet can be stopped and held by an idling load, the sheet can be stopped only by stopping driving transmission by an electromagnetic clutch or the like. It may be configured.

  5 and 7, the unit of the increase / decrease counter of Ls [n] and Lx [n] is 1, but this shows the calculation concept, and the actual increase / decrease unit is the conveyance length unit or time unit in the calculation loop. Needless to say.

  In the examples of the third embodiment, the fourth embodiment, etc., it is possible to prevent misprinting due to double feeding, and to provide a highly productive and reliable apparatus with little downtime. Further, by reducing jams caused by double feeding, it is possible to provide an apparatus with high user operability by eliminating unnecessary jam handling operations. Furthermore, by preventing misprinting due to double feeding, wasteful consumption of paper can be reduced, and an apparatus with less environmental load can be provided.

1 is a front view of an image forming apparatus. FIG. 3 is a front view illustrating a configuration of a main part of the paper transport device. It is an output characteristic figure of a double feed detection means. (A)-(d) is a figure which is 1st Embodiment and demonstrated the double feed cancellation process in a paper conveying apparatus in steps. (A)-(d) is 2nd Embodiment and is the figure explaining stepwise the double feed cancellation process in a paper conveying apparatus. It is the flowchart explaining the double feed cancellation process by a control means in 2nd Embodiment. It is an output characteristic figure of a double feed detection means. FIG. 10 is a diagram illustrating a double feed elimination process in the paper conveying apparatus according to the third embodiment. FIG. 10 is a diagram illustrating a double feed elimination process in the paper conveying apparatus according to the third embodiment. FIG. 10 is a diagram illustrating a double feed elimination process in the paper conveying apparatus according to the third embodiment. FIG. 10 is a diagram illustrating a double feed elimination process in the paper conveying apparatus according to the third embodiment. FIG. 10 is a diagram illustrating a double feed elimination process in the paper conveying apparatus according to the third embodiment. FIG. 10 is a diagram illustrating a double feed elimination process in the paper conveying apparatus according to the third embodiment. FIG. 10 is a diagram illustrating a double feed elimination process in the paper conveying apparatus according to the third embodiment. It is a flowchart explaining the double feed cancellation process by a control means in 3rd Embodiment. It is a flowchart explaining the double feed cancellation process by a control means in 3rd Embodiment. FIG. 10 is a diagram illustrating a double feed elimination process in the paper transport apparatus according to a fourth embodiment. FIG. 10 is a diagram illustrating a double feed elimination process in the paper transport apparatus according to a fourth embodiment. FIG. 10 is a diagram illustrating a double feed elimination process in the paper transport apparatus according to a fourth embodiment. FIG. 10 is a diagram illustrating a double feed elimination process in the paper transport apparatus according to a fourth embodiment. FIG. 10 is a diagram illustrating a double feed elimination process in the paper transport apparatus according to a fourth embodiment. FIG. 10 is a diagram illustrating a double feed elimination process in the paper transport apparatus according to a fourth embodiment. It is a flowchart explaining the double feed cancellation process by a control means in 4th Embodiment. It is a flowchart explaining the double feed cancellation process by a control means in 4th Embodiment.

Explanation of symbols

3 transport roller 3a drive roller 3b driven roller 4 registration roller 4a drive roller 4b driven roller 15 double feed detection means 15a light emitting element 15b light receiving element 20 control means 100 paper transport section S paper S1 preceding paper S2 following paper Lw, Lw1 double feed State transport length Ls, Ls1 Single feed state transport length Lp Paper length Lx Double feed state transport length

Claims (19)

Upstream conveying means for conveying the sheet-like medium;
A multi-feed detecting unit that is disposed downstream of the upstream-side conveying unit in the conveying direction of the sheet-like medium,
A downstream conveying means that is arranged downstream of the double feed detecting means in the conveying direction of the sheet medium, and conveys the sheet medium;
Based on the output from the double feed detection means, it has a control means for controlling the drive stop of the upstream transport means,
The control means stops the conveyance of the sheet-like medium by the upstream-side conveying means based on the fact that the double-feed detecting means detects that the sheet-like medium being conveyed has changed from the double-feed state to the single-feed state. A sheet-like medium conveying apparatus characterized by the above. In the sheet-like medium conveyance device according to claim 1,
The control unit includes a storage unit that holds length information of a multi-feed portion of a sheet medium to be conveyed. Upstream conveying means for conveying the sheet-like medium;
A multi-feed detecting unit that is disposed downstream of the upstream-side conveying unit in the conveying direction of the sheet-like medium,
A downstream conveying means that is arranged downstream of the double feed detecting means in the conveying direction of the sheet medium, and conveys the sheet medium;
Based on the input from the double feed detection means, it has a control means for controlling the drive stop of the upstream transport means,
The control means measures the single-feed state conveyance length before the double-feed detection means detects the double-feed state of the preceding sheet-like medium and the succeeding sheet-like medium, and size information in the conveyance direction of the sheet-like medium The length obtained by subtracting the single-feed state transport length from the multi-feed state portion is defined as the transport length of the double-feed state portion, and at least the double-feed state transport length starting from the time when the trailing edge of the preceding sheet-shaped medium passes through the upstream-side transport unit. The sheet-like medium conveying apparatus stops the conveyance of the sheet-like medium by the upstream-side conveying means until the time required for conveying the sheet elapses. In the sheet-like medium conveyance device according to claim 3,
The sheet medium conveying apparatus, wherein the control unit includes a storage unit that holds size information in a conveyance direction of the sheet medium to be conveyed. In the sheet-like medium conveyance device according to any one of claims 1 to 4,
The upstream medium conveying unit and the downstream medium conveying unit each include a pair of opposed rollers, and one of the paired rollers is a driving roller. In the sheet-like medium conveyance device according to any one of claims 1 to 5,
The control unit measures the conveyance length in the double-feed state, and stops the conveyance of the sheet-like medium by the upstream-side conveyance unit for at least a time corresponding to the double-feed state conveyance length. apparatus. In the sheet-like medium conveyance device according to any one of claims 1 to 6,
The multi-feed detection means is an optical detection means. In the sheet-like medium conveyance device according to any one of claims 1 to 7,
The sheet-like medium conveyance device, wherein the double-feed detection means can also be used as another sensor provided in a conveyance system. In the sheet-like medium conveyance device according to any one of claims 1 to 8,
The sheet-like medium conveyance device, wherein the downstream side conveyance means is a registration roller.   An image forming apparatus comprising the sheet-like medium conveyance device according to claim 1.   When the sheet-like medium is conveyed with a conveyance driving force applied by the upstream-side conveyance means and the downstream-side conveyance means, the weight in a state where the trailing edge of the preceding sheet-shaped medium and the leading edge of the succeeding sheet-shaped medium overlap each other. When the transport state conveyance length region passes through the upstream conveyance unit, the conveyance driving force by the upstream conveyance unit is stopped to stop conveyance of the subsequent sheet-like medium, and the downstream conveyance unit The sheet-like medium conveying method is characterized in that the conveyance driving force is continuously applied to advance the preceding sheet-like medium while leaving the succeeding sheet-like medium to eliminate the double feed state. In the sheet-like medium conveyance method according to claim 11,
When the double-feed state is resolved, the sheet-like medium conveyance method revives the conveyance of the succeeding sheet-like medium by the upstream-side conveyance unit.   A conveying unit that conveys the sheet-like medium; and a multi-feed detecting unit that is arranged downstream of the conveying unit and detects a multi-feed of a plurality of sheet-like media being conveyed. A sheet-like medium conveying apparatus, wherein the conveying means is stopped based on detection of a decrease in the number of sheets. In the sheet-like medium conveyance device according to claim 13,
The control means measures and stores the transport length in the double feed state for each double feed number detected by the double feed detection means, and sequentially stops the transport means for a time corresponding to the transport length in the double feed state. A sheet-like medium conveying apparatus characterized by the above. A conveyance unit that conveys the sheet-like medium, a multi-feed detection unit that is arranged downstream of the conveyance unit and detects a multi-feed of the sheet-like medium being conveyed, and stores and holds the size of the sheet-like medium to be conveyed A sheet-like medium transport device having sheet-like medium size storage means and control means for controlling them,
The control unit includes a conveyance state length storage unit that measures and stores a conveyance length in the conveyance state for each multifeed number detected by the multifeed detection unit,
The length obtained by subtracting the conveyance length obtained from the conveyance state length storage unit from the length of the sheet medium obtained from the sheet medium storage unit is the conveyance length in the double feed state,
A sheet-like medium conveying apparatus which sequentially stops the conveying means for a time corresponding to the conveyance of the double-feed state conveying length after the trailing edge of the preceding sheet-like medium passes through the conveying means. In the sheet-like medium conveyance device according to any one of claims 13 to 15,
The multi-feed detection means is an optical detection means. In the sheet-like medium conveyance device according to any one of claims 13 to 15,
The sheet-like medium conveyance device, wherein the double feed detection means can be used also as another sensor provided in a conveyance system. In the sheet-like medium conveyance device according to any one of claims 13 to 15,
A sheet-like medium carrying device having a second carrying means downstream of the double feed detecting means, wherein the second carrying means is a registration roller.   An image forming apparatus comprising image forming means for forming an image on a sheet-like medium conveyed by the sheet-like medium conveying apparatus according to claim 13.

Images