JP2005330016A - Paper conveyance device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent load fluctuation of a pair of feed rolls from affecting paper conveyance speed by a pair of register rolls adversely even when the pair of feed rolls and the pair of register rolls are arranged in a line on a conveyance path. <P>SOLUTION: In this paper conveyance device provided with the pair of feed rolls 4 handling paper sheets 2 fed from a paper feeding tray 1 every paper sheet for conveyance and the pair of register rolls 5 for nipping, holding, and conveying the paper sheet 2 onto a rear step side by operating at predetermined timing after compensating skew of the paper sheet 2 by butting the paper sheet 2 to arrange the pair of feed rolls 4 and the pair of register rolls 5 in a line on the conveyance path 6, a speed control means 12 for controlling speed for the pair of register rolls 5 for preventing load fluctuation due to stop from transmitting to the paper sheet by corresponding to timing for stopping driving of the pair of feed rolls 4 for conveying the paper sheet 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sheet conveying device used for a copying machine, a printer device, and the like.

In general, a copying machine, a printer device, and the like are equipped with a paper transport device for transporting paper stored in a paper feed tray to an image forming unit that transfers a toner image onto the paper.
As a sheet conveying device, for example, one configured as shown in FIG. 4 is widely known. In the illustrated sheet conveying apparatus, a pickup roll 23 that feeds out a sheet 22 from a sheet feeding tray 21, a feed roll pair 24 that conveys the sheet 22 fed out to the pickup roll 23 on each leaf, and its feed A takeaway roll pair 25 disposed on the rear side of the sheet conveying direction with respect to the roll pair 24 and a registration roll pair 26 disposed on the rear side of the takeaway roll pair 25 are further provided. Then, when the paper 22 is fed out from the feed roll pair 24 one by one, the takeaway roll pair 25 abuts against the registration roll pair 26 that is nipping and transporting the paper 22 toward the rear side and stopped. Thus, after correcting the skew (inclination) of the sheet, the registration roll pair 26 starts rotating in accordance with the operation timing of the image forming unit (not shown), and the sheet 22 is directed toward the image forming unit on the rear side. It is designed to be nipped and conveyed.

  At this time, the conveyance speed of the sheet 22 by the registration roll pair 26 needs to be synchronized with the image formation speed in the image forming unit. This is because if the respective speeds are not synchronized, an image formation failure or the like due to a shift in the sheet conveyance timing to the image forming unit is caused. For this reason, it has been proposed to perform so-called feedback control on the roll rotation speed of the registration roll pair 26 based on, for example, the detection result of the loop amount generated on the paper (see, for example, Patent Document 1).

  In recent years, there has been a strong demand for miniaturization, low power consumption, low price, and the like for copying machines and printer devices. Along with this, some paper transport devices eliminate the takeaway roll pair, and the feed roll pair and the registration roll pair are arranged side by side on the paper transport path (for example, see Patent Document 2). ).

Japanese Patent Laid-Open No. 01-176746 JP 2002-255403 A

  By the way, in the sheet conveying apparatus in which the feed roll pair and the registration roll pair are arranged side by side, there is no takeaway roll pair, so the influence of the load fluctuation on the feed roll pair directly affects the registration roll pair. For example, the feed roll pair stops rotating before the trailing edge of the sheet passes in order to prevent double feeding of the sheet. However, the load fluctuation due to the stop of the rotating operation naturally affects the pair of registration rolls. In addition, when the rear end of the sheet exits the pair of feed rolls that have stopped rotating, a sudden load fluctuation occurs on the sheet. Therefore, in the paper transporting device in which the feed roll pair and the registration roll pair are arranged side by side, the registration roll pair may not be able to transport the paper at a constant speed due to the influence of load fluctuations in the feed roll pair.

Such a disturbance in the sheet conveyance speed in the pair of registration rolls causes an image formation defect due to a deviation in the sheet conveyance timing to the image forming unit, specifically, a color deviation or a smear. Therefore, for example, as disclosed in Patent Document 1, it is conceivable to correct the disturbance in the paper conveyance speed by performing feedback control based on the detection result of the actual paper conveyance speed.
However, for a sudden load fluctuation that occurs when the trailing edge of the paper leaves the feed roll pair, the response is not always in time even if feedback control is performed. In addition, when trying to improve the responsiveness of the feedback control, a complicated configuration, complicated processing, and the like are required, which is not preferable in realizing downsizing, low power consumption, low price, and the like of the apparatus.

  Therefore, the present invention easily realizes downsizing, low power consumption, low price, etc. of the apparatus even when the feed roll pair and the registration roll pair are arranged side by side on the paper conveyance path. An object of the present invention is to provide a paper transport device that enables the load fluctuation in the feed roll pair to not adversely affect the paper transport speed of the registration roll pair.

  The present invention is a sheet conveying device devised to achieve the above object. That is, a pair of feed rolls that transports the paper fed out from the paper feed tray every leaf, and operates at a predetermined timing after correcting the skew of the paper by abutting the paper, and holds the paper to the subsequent stage side A pair of registration rolls for conveying the sheet, and the pair of feed rolls and the pair of registration rolls are arranged side by side on a conveyance path of the sheet, and the pair of feed rolls for conveying the sheet Corresponding to the timing at which the driving stops, there is provided speed control means for performing speed control on the pair of registration rolls so as not to transmit the load fluctuation caused by the stop to the sheet.

According to the paper transport device having the above configuration, the speed control unit performs speed control on the registration roll pair in response to the timing at which the drive of the feed roll pair is stopped. Specifically, for example, when the drive of the feed roll pair is stopped, the speed of the registration roll pair is increased in accordance with the increase of the load due to the stop, and when the rear end of the paper passes through the stopped feed roll pair, the load on the paper is reduced. For example, the speed of the registration roll pair is decreased in accordance with the rapid load fluctuation because the abrupt exit occurs. The timing at this time can be specified from a series of operation sequences in the feed roll pair and the registration roll pair.
Therefore, even if there is a load fluctuation due to the drive stop of the feed roll pair, the influence is not transmitted to the sheet conveyance by the registration roll pair. In addition, since speed control may be performed in correspondence with timings that can be specified from a series of operation sequences, there is no problem with response to sudden load fluctuations.

  The paper transport device according to the present invention has a speed with respect to the pair of registration rolls corresponding to the timing of stopping the driving of the pair of feed rolls even when the pair of feed rolls and the pair of registration rolls are arranged side by side on the paper transport path. Since the control is performed, the influence of the load fluctuation due to the drive stop is not transmitted to the sheet conveyance by the registration roll pair, and the response to the sudden load fluctuation does not become a problem. Therefore, according to the paper conveyance device of the present invention, it is possible to easily realize downsizing, low power consumption, low price, etc. of a copying machine or a printer device in which the paper conveyance device is mounted, and the paper by the registration roll pair. As a result, the conveyance speed can be stabilized, and as a result, the deviation of the sheet conveyance timing to the image forming unit can be avoided and the image formation on the sheet can be satisfactorily performed.

  Hereinafter, a sheet conveying apparatus according to the present invention will be described with reference to the drawings. The paper conveying apparatus described here is used by being mounted on a copying machine, a printer apparatus, or the like. Since the copying machine, the printer apparatus, or the like is realized by a publicly known technique, the description thereof will be given here. Is omitted.

[First Embodiment]
First, a first embodiment of a paper conveying apparatus according to the present invention will be described.

  FIG. 1 is a schematic diagram illustrating an example of a schematic configuration of a sheet conveying device according to the first embodiment. In the illustrated sheet conveying apparatus, a pickup roll 3 that feeds out a sheet 2 from a sheet feeding tray 1, a feed roll pair 4 that conveys the sheet 2 that has been fed out to the pickup roll 3 on each leaf, and its feed A registration roll pair 5 is provided on the rear side of the sheet conveying direction with respect to the roll pair 4. That is, the feed roll pair 4 and the registration roll pair 5 are arranged side by side on the conveyance path 6 of the paper 2, and no takeaway roll pair is arranged between them. A feed sensor 7 and a registration sensor 8 for detecting the presence / absence (passage) of the sheet 2 may be provided on the conveyance path 6 between the feed roll pair 4 and the registration roll pair 5.

  In the sheet conveying apparatus configured as described above, the sheet stored in the sheet feeding tray 1 is conveyed to an image forming unit (not shown) such as a copying machine or a printer that transfers a toner image onto the sheet. In doing so, the following processing operations are performed. That is, when the pickup roll 3 feeds the paper 2 from the paper feed tray 1, the paper 2 is conveyed toward the registration roll pair 5, which is stopped rotating, while the feed roll pair 4 is sprinkling every leaf. Then, after correcting the skew of the sheet 2 by causing the leading edge of the sheet 2 to abut against the registration roll pair 5 to generate a bending loop in the sheet 2, the registration roll pair 5 rotates in accordance with the operation timing of the image forming unit. The sheet 2 is nipped and conveyed toward the image forming unit on the rear stage side. At this time, the sheet is conveyed while being sandwiched between both the feed roll pair 4 and the registration roll pair 5. Thereafter, the feed roll pair 4 stops rotating before the trailing edge of the paper 2 passes through the feed roll pair 4 in order to prevent double feeding of the paper. Further, when the trailing edge of the sheet 2 passes the registration roll pair 5, the registration roll pair 5 stops rotating in preparation for skew correction of the next sheet 2.

  By the way, when performing such processing operation, the feed roll pair 4 is rotationally driven by a feed motor 9 which is a driving source thereof. Further, the registration roll pair 5 is rotationally driven by a registration motor 10 which is a driving source thereof. At this time, a drive transmission means such as a gear or a belt may be provided between the roll pairs 4 and 5 and the motors 9 and 10 as necessary. Each of the motors 9 and 10 is instructed to rotate by a control means 11 such as a CPU (Central Processing Unit) that executes a predetermined program. That is, each of the motors 9 and 10 is configured to start or stop the rotation operation at the timing described above in accordance with an instruction from the control unit 11. The control unit 11 instructs the motors 9 and 10 based on the operation timing of the image forming unit, the detection result by the feed sensor 7 or the registration sensor 8, the measurement result of the elapsed time by the timer function, and the like. And

  The configuration and processing operations described above are substantially the same as those of the conventional paper transport device. However, in the paper transport device according to the present embodiment, in addition to the above-described configuration, the speed control means 12 and Information storage means 13 is provided.

  The speed control means 12 makes the operation speed of the registration motor 10, that is, the rotation speed of the registration roll pair 5 by the registration motor 10 variable. For example, if the registration motor 10 is a stepping motor, the speed variable unit 12 may be realized by a controller that changes the drive frequency (number of pulses) applied to the registration motor 10 or a CPU that controls the controller. In addition, the rotational speed of the registration roll pair 5 may be made variable by changing the voltage applied to the registration motor 10 or changing the gear ratio in the drive transmission means. However, the speed control unit 12 varies the operation speed of the registration motor 10 based on information on the speed profile stored in the information storage unit 13 as described later.

  The information storage means 13 stores information related to a predetermined speed profile. The information storage means 13 may be realized by a storage device such as a RAM (Random Access Memory) or a ROM (Read Only Memory) accessible by the speed control means 12 described above. Alternatively, a plurality of predetermined speed profiles may be prepared and selectable depending on the type of paper to be fed.

  Here, information on the speed profile (hereinafter simply referred to as “speed profile information”) stored in the information storage unit 13 will be described. The speed profile information means that when the feed roll pair 4 stops driving during the series of processing operations described above, the load transmitted to the paper 2 fluctuates due to the stop, but the speed at which the load fluctuation is not transmitted to the paper 2. Information that is necessary for control. Specifically, for example, when the drive of the feed roll pair 4 is stopped, the load on the paper 2 increases due to the stop, so that the operating speed of the registration motor 10 is increased according to the load fluctuation, and the rear end of the paper 2 is When passing through the stopped feed roll pair 4, the load on the paper 2 is abruptly removed, so that the speed control information is such that the operation speed of the registration motor 10 is reduced in accordance with the rapid load fluctuation. is there. That is, the speed profile information is information for specifying the relationship between the driving of the feed roll pair 4 and the change in the operation speed of the registration motor 10. Such speed profile information may be specified in advance based on, for example, an empirical rule based on experiments or the like.

  Next, an example of processing operation in the case where the speed control unit 12 varies the operation speed of the registration motor 10 in the sheet conveying apparatus configured as described above will be described.

  As already described, during the series of processing operations described above, the control means 11 controls the feed motor 9 before the trailing edge of the paper 2 passes the feed roll pair 4 in order to prevent double feeding of the paper. To stop driving. This drive stop instruction is also given to the speed control means 12. In response to this drive stop instruction, the speed control means 12 accesses the information storage means 13 to acquire speed profile information, and further increases the speed of the operating registration motor 10, for example, based on the speed profile information. As a result, the operation speed of the registration motor 10 increases in accordance with the timing at which the feed motor 9 stops driving.

  Further, after a drive stop instruction to the feed motor 9, when a predetermined time uniquely specified from the operation speed of the registration motor 10 has elapsed, the rear end of the sheet 2 passes through the stopped feed roll pair 4. As time elapses, the speed control means 12 accesses the information storage means 13 to acquire speed profile information, and reduces, for example, the speed of the operating registration motor 10 based on the speed profile information. As a result, the operation speed of the registration motor 10 decreases in accordance with the timing at which the rear end of the sheet 2 passes through the feed roll pair 4.

  As described above, the speed control unit 12 controls the operation speed of the registration motor 10, that is, the speed control for the registration roll pair 5 in accordance with the timing at which the driving of the feed roll pair 4 stops. As described above, “corresponding” to the timing here means, in addition to the timing at which driving of the feed roll pair 4 stops, until the predetermined time elapses after the timing, specifically, the sheet 2 This includes the time until the rear end of the feed roller pair 4 passes through. The “timing” corresponding to the speed control means 12 can be specified from a series of operation sequences in the feed roll pair 4 and the registration roll pair 5.

  By the speed control by the speed control unit 12, even if there is a load fluctuation due to the drive stop of the feed roll pair 4, the influence is not transmitted to the paper transport by the registration roll pair 5 in the paper transport apparatus in the present embodiment. . In addition, since speed control may be performed in accordance with timing that can be specified from a series of operation sequences, response to sudden load fluctuations does not become a problem. That is, even when the feed roll pair 4 and the registration roll pair 5 are arranged side by side on the sheet conveyance path 6, the speed control for the registration roll pair 5 is performed in accordance with the drive stop timing of the feed roll pair 4. Therefore, the influence of the load fluctuation due to the drive stop is not transmitted to the sheet conveyance by the registration roll pair 5, and the response to the sudden load fluctuation does not become a problem.

  Therefore, according to the paper transport device of the present embodiment, the registration roll pair 5 can transport the paper 2 at a constant speed even if there is an influence of load fluctuations in the feed roll pair 4. That is, since the disturbance of the sheet conveyance speed in the registration roll pair 5 can be prevented, the image formation failure due to the deviation of the sheet conveyance timing to the image forming unit, specifically, the occurrence of color deviation, smear and the like will not be caused. Therefore, by using the paper transport device of this embodiment, it is possible to easily realize downsizing, low power consumption, low price, etc. of a copying machine or a printer device equipped with the paper transport device, The sheet conveyance speed can be stabilized by the pair 5, and as a result, the deviation of the sheet conveyance timing to the image forming unit can be avoided and the image formation on the sheet 2 can be performed satisfactorily.

[Second Embodiment]
Next, a second embodiment of the paper conveying apparatus according to the present invention will be described. However, the description of the same contents as those in the first embodiment described above is omitted.

  FIG. 2 is a schematic diagram illustrating a schematic configuration example of the sheet conveying device according to the second embodiment. In the illustrated sheet conveying apparatus, an encoder 14 is provided on at least one roller constituting the registration roll pair 5, for example, the registration pinch roll 5a, for detecting the rotational speed of the roll. As the encoder 14, any encoder may be used as long as it is configured using a known technique such as detecting a slit provided in a disk interlocked with the pinch roll 5 a with a sensor. The encoder 14 only needs to be able to detect the rotational speed of the pair of registration rolls 5, and can detect the rotational speed of the pinch roll 5 a or the rotational speed per unit time. There may be.

  By providing such an encoder 14, the speed control means 12 controls the operating speed of the registration motor 10 so as to keep the roll rotation speed in the registration roll pair 5 constant based on the detection result by the encoder 14. It has become. That is, the speed control means 12 performs feedback control on the registration motor 10 based on the detection result by the encoder 14. Thus, for example, even if the registration roll pair 5 is eccentric, the speed control means 12 detects the 1 / x cycle of the data for one rotation of the roll in order to cancel the roller eccentricity, and determines the operation speed of the registration motor 10. And so on. Note that the feedback control itself may be realized using a known technique, and thus detailed description thereof is omitted here.

  However, for a sudden load fluctuation that occurs when the trailing edge of the sheet 2 passes through the feed roll pair 4, even if the feedback control as described above is performed, the response is not always in time. In addition, when trying to improve the responsiveness of the feedback control, a complicated configuration, complicated processing, and the like are required, which is not preferable in realizing downsizing, low power consumption, low price, and the like of the apparatus.

  For this reason, in the paper conveying apparatus described in this embodiment, in addition to the feedback control described above, when the feed roll pair 4 is stopped, speed control is performed according to the speed profile information stored in the information storage unit 13. It has become. That is, the speed control means 12 performs feedback control on the registration motor 10 based on the detection result by the encoder 14, and performs speed control according to the speed profile information corresponding to the timing when the drive of the feed roll pair 4 stops. Also do. Note that the speed control according to the speed profile information may be performed in the same manner as in the first embodiment described above.

  As described above, according to the paper conveying apparatus of the present embodiment, speed control according to the speed profile information is performed in addition to the feedback control, so even if there is a sudden load fluctuation on the paper 2, the load fluctuation is assumed. Speed control can be performed based on the speed profile information. Therefore, it is possible to quickly respond to sudden load fluctuations, and it is possible to avoid the problem of responsiveness. In addition, no complicated configuration or complicated processing is required.

[Third Embodiment]
Next, a third embodiment of the paper conveying apparatus according to the present invention will be described. However, also here, the description of the same contents as those of the first or second embodiment described above is omitted.

  FIG. 3 is a schematic diagram illustrating a schematic configuration example of the sheet conveying device according to the third embodiment. In the illustrated sheet conveying apparatus, a loop amount detection sensor 16 for detecting the loop amount of the sheet 2 nipped and conveyed by the registration roll pair 5 between the registration roll pair 5 and the image forming unit 15 located at the subsequent stage. Is provided. The loop amount detection sensor 16 may be any sensor configured using a known technique such as detecting the distance from the paper surface of the paper 2 in a non-contact manner using, for example, a laser or light.

  By providing such a loop amount detection sensor 16, the speed control means 12 causes the operating speed of the registration motor 10 to keep the loop amount of the paper 2 at a predetermined amount based on the detection result by the loop amount detection sensor 16. Is to control. That is, the speed control unit 12 performs feedback control on the registration motor 10 based on the detection result by the loop amount detection sensor 16. As a result, the speed control unit 12 is configured so that the conveyance speed of the sheet 2 nipped and conveyed by the pair of registration rollers 5, for example, matches the operation processing speed in the image forming unit 1, that is, a bending loop generated in the sheet 2 due to the speed difference Thus, the operation speed of the registration motor 10 can be controlled so as to be equal to or less than a predetermined amount (allowable amount). Note that the feedback control itself may be realized using a known technique, and thus detailed description thereof is omitted here.

  However, for a sudden load fluctuation that occurs when the trailing edge of the sheet 2 passes through the feed roll pair 4, even if the feedback control as described above is performed, the response is not always in time. In addition, when trying to improve the responsiveness of the feedback control, a complicated configuration, complicated processing, and the like are required, which is not preferable in realizing downsizing, low power consumption, low price, and the like of the apparatus.

  For this reason, in the paper conveying apparatus described in this embodiment, in addition to the feedback control described above, when the feed roll pair 4 is stopped, speed control is performed according to the speed profile information stored in the information storage unit 13. It has become. That is, the speed control means 12 performs feedback control on the registration motor 10 based on the detection result by the loop amount detection sensor 16 and follows the speed profile information corresponding to the timing when the drive of the feed roll pair 4 stops. Also performs speed control. Note that the speed control according to the speed profile information may be performed in the same manner as in the first embodiment described above.

  As described above, in the paper conveying apparatus of the present embodiment, as in the case of the second embodiment described above, speed control according to the speed profile information is performed in addition to the feedback control. Even if there is a significant load fluctuation, the speed control can be performed based on the speed profile information that assumes the load fluctuation. Therefore, it is possible to quickly respond to sudden load fluctuations, and it is possible to avoid the problem of responsiveness. In addition, no complicated configuration or complicated processing is required.

  In the first to third embodiments described above, preferred specific examples of the present invention have been described. However, the present invention is not limited to the contents described in these embodiments. That is, the present invention can be appropriately changed without departing from the gist thereof, and can be realized by appropriately combining the contents described in the first to third embodiments, for example.

FIG. 3 is a schematic diagram illustrating a schematic configuration example in the first embodiment of the paper conveying apparatus according to the present invention. It is a schematic diagram which shows the schematic structural example in 2nd Embodiment of the paper conveying apparatus which concerns on this invention. It is a schematic diagram which shows the schematic structural example in 2nd Embodiment of the paper conveying apparatus which concerns on this invention. FIG. 10 is a schematic diagram illustrating a schematic configuration example of a conventional paper conveyance device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Paper feed tray, 2 ... Paper, 3 ... Pickup roll, 4 ... Feed roll pair, 5 ... Registration roll pair, 6 ... Conveyance path, 9 ... Feed motor, 10 ... Registration motor, 11 ... Control means, 12 ... Speed control means , 13 ... information storage means, 14 ... encoder, 15 ... image forming unit, 16 ... loop amount detection sensor

Claims (4)

A pair of feed rolls that transport the paper fed out from the paper feed tray every leaf, and correct the skew of the paper by abutting the paper and operate at a predetermined timing to nipping and transport the paper to the subsequent stage side A sheet conveying device including a pair of registration rolls, wherein the pair of feed rolls and the pair of registration rolls are arranged side by side on a conveyance path of the sheet,
Corresponding to the timing when driving of the feed roll pair for transporting the paper stops, speed control means for performing speed control on the registration roll pair so as not to transmit the load fluctuation due to the stop to the paper. Characteristic paper transport device. The sheet conveying apparatus according to claim 1, wherein the speed control unit performs speed control on the pair of registration rolls according to a predetermined speed profile. A speed detecting means for detecting a roll rotation speed in the registration roll pair;
The speed control means performs speed control on the registration roll pair so as to keep the roll rotation speed constant based on a detection result by the speed detection means, and in addition to the speed control when driving of the feed roll pair is stopped. The sheet conveying apparatus according to claim 2, wherein speed control is performed according to the speed profile. Loop amount detecting means for detecting a loop amount of the paper generated in the paper that is nipped and conveyed between the pair of registration rolls;
The speed control unit performs speed control on the registration roll pair so as to keep the loop amount of the paper at a predetermined amount based on a detection result by the loop amount detection unit, and performs the speed control when driving of the feed roll pair is stopped. The sheet conveying apparatus according to claim 2, wherein speed control is performed according to the speed profile.

Images