JP2005324899A - Sheet transport device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To preclude occurrence of a delay in sheet transport due to wear of a feed roller, a change in the transporting speed relationship with a resist roller pair, etc. even if a feed roller pair and the resist roller pair are arranged lying in line on the sheet transporting path. <P>SOLUTION: The sheet transport device is equipped with the feed roller pair 4 to transport paper sheets 2 paid off from a sheet feed tray 1 upon being separated sheet by sheet and the resist roller pair 5 to be actuated at the specified timing after skew correction with abutting of the sheet 2 and to pinch the sheet 2 and transport toward the later stage, in which the feed roller pair 4 and the resist roller pair 5 are arranged lying in line on the transporting path 6, and the arrangement further includes a speed changing means 10 to change the rotating speed of the feed rollers 4a in the pair 4. <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. 8 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, and a feed roll 24 a and a retard roll 24 b that convey the sheet 22 fed out to the pickup roll 23 on a leaf-by-leaf basis. A pair of feed rolls 24, a takeaway roll pair 25 disposed on the rear side of the sheet conveying direction with respect to the feed roll pair 24, and a registration roll pair 26 disposed on the rear side of the takeaway roll pair 25. ing. 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.

  Incidentally, 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 1). ).

JP 2002-255403 A

  However, in a paper transporting device in which a feed roll pair and a registration roll pair are arranged side by side, for example, the feed roll must transport the paper for a long distance to the registration roll pair. Compared to the case where there is a pair of takeaway rolls, the paper conveyance load on the feed roll becomes large. Therefore, the occurrence of wear of the feed roll becomes significant, and there is a possibility that a paper conveyance delay may occur or the relationship with the paper conveyance speed by the registration roll pair may change. Such a paper conveyance delay or a change in the conveyance speed relationship with the pair of registration rolls may result in an uncertain correction of the paper skew or an image formation failure due to a deviation in the paper conveyance timing to the image forming unit. Therefore, it should be avoided.

  In view of this, the present invention relates to a paper feed delay due to wear of the feed roll and a transport speed relationship with the register roll pair even when the feed roll pair and the registration roll pair are arranged side by side on the paper transport path. It is an object of the present invention to provide a paper transport device that does not change.

  The present invention is a sheet conveying device devised to achieve the above object. In other words, a feed roll pair consisting of a feed roll and a retard roll that conveys the paper fed from the paper feed tray every leaf, and the skew of the paper is corrected by abutting the paper, and operates at a predetermined timing. A pair of registration rolls for nipping and conveying the sheet to the rear side, and the feed roll pair and the registration roll pair arranged side by side on the sheet conveyance path, It is characterized by comprising speed variable means for making the rotational speed variable.

  According to the paper transport device having the above configuration, since the speed variable means for changing the rotation speed of the feed roll is provided, for example, even when the roll diameter is reduced due to wear of the feed roll, It is possible to increase the rotation speed in accordance with the decrease in the roll diameter. Therefore, even if the roll diameter of the feed roll changes, it is possible to avoid the occurrence of a paper conveyance delay or a change in the relationship with the paper conveyance speed by the registration roll pair.

  The paper transport device according to the present invention can reduce the paper transport delay by changing the rotation speed of the feed roll even when the feed roll pair and the registration roll pair are arranged side by side on the paper transport path. Since it is possible to avoid changes in the conveyance speed relationship with the pair of registration rolls, it is possible to realize downsizing, low power consumption, low price, etc. of a copying machine or printer device equipped with the paper conveyance device. As a result, the skew correction of the sheet can be ensured, and the deviation of the sheet conveyance timing to the image forming unit can be avoided, and the image formation on the sheet can be favorably 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 the sheet 2 from the sheet feeding tray 1, and a feed roll 4 a and a retard roll 4 b that convey the sheet 2 fed out to the pickup roll 3 on every leaf. A feed roll pair 4 and a registration roll pair 5 disposed on the rear stage side in the paper transport direction with respect to the feed 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. 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 pick-up roll 3 feeds the paper 2 from the paper feed tray 1, the feed roll 4a and the retard roll 4b are rotated reversely to each other, and the feed roll pair 4 stops rotating. The sheet 2 is conveyed toward the registration roll pair 5 that is present. 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 rotation operation is stopped in preparation for the skew correction of the next sheet 2.

By the way, when performing such processing operation, the feed roll 4a is rotationally driven by a feed motor 9 which is a driving source thereof. At this time, drive transmission means such as a gear or a belt may be provided as necessary. However, it is assumed that the rotational speed of the feed roll 4a that is rotationally driven is variable.
That is, the paper conveying apparatus described here includes a speed variable means 10 that makes the rotation speed of the feed roll 4a variable. For example, if the feed motor 9 is a stepping motor, the speed variable means 10 is controlled by a controller that changes the drive frequency (number of pulses) applied to the feed motor 9 or a CPU (Central Processing Unit) that controls the controller. Realize it. In addition, the rotation speed of the feed roll 4a may be made variable by changing the voltage applied to the feed motor 9 or changing the gear ratio in the drive transmission means.

  In addition, the sheet conveying apparatus described in the present embodiment is provided with an information storage unit 11 that stores information related to a secular variation of the roll diameter of the feed roll 4 a in association with the speed variable unit 10. The information storage means 11 may be realized by a storage device such as a RAM (Random Access Memory) or a ROM (Read Only Memory) accessible by the speed variable means 10 described above.

  Here, the “information relating to the secular variation of the roll diameter” stored in the information storage unit 11 will be described. FIG. 2 is an explanatory diagram showing a specific example of information related to the secular variation of the roll diameter. As shown in the example of the figure, as information on the variation of the roll diameter with time, information specifying the relationship between the amount of wear of the feed roll 4a (the amount of decrease in the roll diameter due to wear) and the amount of rotation of the feed roll 4a. Can be considered. Among these, the rotation amount of the feed roll 4a may be specified by, for example, the total number of sheets fed (feeded number of sheets) by the feed roll 4a, the total number of rotations, or the total running paper length. However, each relationship is clarified based on, for example, an empirical rule based on experiments or the like, and is stored in advance in the information storage unit. Needless to say, each relationship is not necessarily a proportional relationship as shown in the figure.

  By attaching the information storage unit 11 as described above, the speed variable unit 10 can change the rotation speed of the feed roll 4 a based on information stored in the information storage unit 11. Here, “based on” includes not only the case where the information stored in the information storage unit 11 is used as it is, but also the case where the information is multiplied by a predetermined coefficient for feeding back an error factor, for example. means. Note that the predetermined coefficient in the case where the predetermined coefficient is used is assumed to be stored in advance in a table format, for example, in a storage device accessible by the information storage unit 11 or the speed variable unit 10.

  Next, an example of processing operation when the speed variable unit 10 changes the rotation speed of the feed roll 4a in the sheet conveying apparatus configured as described above will be described. FIG. 3 is a flowchart showing an example of processing operation with variable rotation speed in the first embodiment. As shown in the figure, in the paper transport device, when a print start instruction is issued from a control unit such as a copying machine or a printer device in which the paper transport device is mounted, the following processing operation is performed.

  First, the speed variable means 10 accesses the information storage means 11 and obtains information related to the secular variation of the roll diameter of the feed roll 4a (step 101; hereinafter, step is abbreviated as “S”). Specifically, the speed variable means 10 performs, for example, the total amount relating to the total number of feeds of the paper by the feed roll 4a, the total number of rotations, or the total running paper length as the rotation amount of the feed roll 4a from the start of operation of the apparatus. Or the amount of wear of the feed roll 4a corresponding to the rotation amount of the feed roll 4a, which is obtained from a control unit such as a copying machine or a printer that performs accumulation related to these, or the acquired amount of information. Get from 11. After obtaining the information from the information storage means 11, the speed variable means 10 then obtains coefficient information from the information storage means 11 or a storage device accessible by the speed variable means 10 (S102). The acquisition of coefficient information is not always essential.

  Thereafter, the speed variable means 10 determines the rotational speed of the feed roll 4a after the change, based on the wear amount of the obtained feed roll 4a and the coefficient information when the coefficient information is acquired (S103). . At this time, the speed varying means 10 determines the rotational speed of the feed roll 4a so that the roll peripheral speeds of the feed roll 4a and the registration roll pair 5 coincide. Therefore, the speed variable means 10 increases the rotation speed of the feed roll 4a according to the amount of wear of the feed roll 4a. The rotational speed can be easily determined by programming an arithmetic expression corresponding to the fixed value in the speed variable means 10 in advance because the roll peripheral speed of the registration roll pair 5 is a fixed value. Is possible. When the rotational speed of the feed roll 4a is determined, the speed variable means 10 outputs the drive frequency at which the feed roll 4a operates at the determined rotational speed to the feed motor 9 (S104).

  As a result, the feed roll 4 a is driven at a rotational speed that matches the roll peripheral speed of the registration roll pair 5, and transports the paper 2 fed out by the pickup roll 3 toward the registration roll pair 5. Then, the sheet 2 is transported at the rotational speed until the rotation operation stop timing before the rear end of the sheet 2 passes the feed roll pair 4.

  As described above, according to the paper conveying apparatus described in the present embodiment, since the speed variable means 10 for changing the rotational speed of the feed roll 4a is provided, for example, the feed roll 4a is worn and the roll Even when the diameter is reduced, the rotational speed can be increased in accordance with the decrease in the roll diameter. Therefore, even if the roll diameter of the feed roll 4 a changes, it is possible to avoid the occurrence of a paper transport delay or a change in the relationship with the paper transport speed by the registration roll pair 5. That is, even when the feed roll pair 4 and the registration roll pair 5 are arranged side by side on the paper conveyance path 6, the conveyance speed of the paper 2 and the registration roll can be changed by changing the rotation speed of the feed roll 4a. It is possible to avoid a change in the conveyance speed relationship with the pair 5 or the like. Accordingly, it is possible to ensure the skew correction of the paper 2 while ensuring the miniaturization, the low power consumption, the low price, etc. of the copying machine or the printer device on which the paper transport device is mounted, and the image formation. This makes it possible to favorably form an image on the paper 2 while avoiding the deviation of the paper conveyance timing to the section.

  Further, according to the paper conveying apparatus described in the present embodiment, the rotation of the feed roll 4a is based on the information stored in the information storage unit 11, that is, the information related to the secular variation of the roll diameter of the feed roll 4a stored in advance. Since the speed is varied, the rotational speed can be easily varied with a simple configuration that does not require a sensor or the like.

[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. 4 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, a roll diameter detecting means 12 for detecting fluctuations in the roll diameter of the feed roll 4a is provided in the vicinity of the feed roll 4a. Examples of the roll diameter detecting means 12 include those realized by using a sensor that detects the distance from the peripheral surface of the feed roll 4a in a non-contact manner using a laser, light, or the like. In addition, it is conceivable to realize this by bringing one end of a swingable contact into contact with the peripheral surface of the feed roll 4a and detecting the displacement of the other end of the contact with a sensor.

  Since such a roll diameter detecting means 12 is provided, in the paper conveying apparatus described in the present embodiment, the speed variable means 10 changes the rotation speed of the feed roll 4a and the detection result by the roll diameter detecting means 12 is obtained. Based on this. This “based on” is the same as the description in the first embodiment.

  Next, an example of processing operation when the speed variable unit 10 changes the rotation speed of the feed roll 4a in the sheet conveying apparatus configured as described above will be described. FIG. 5 is a flowchart showing an example of processing operation with variable rotation speed in the second embodiment. As shown in the figure, in the paper transport device, when there is a print start instruction, the following processing operation is performed.

  First, the speed variable means 10 obtains information related to the fluctuation of the roll diameter of the feed roll 4a from the detection result by the roll diameter detection means 12 (S201). Specifically, for example, if the roll diameter detecting means 12 is composed of a sensor that detects the distance from the peripheral surface of the feed roll 4a, the relationship between the detected distance and the roll diameter of the feed roll 4a is uniquely determined. Therefore, the correspondence relationship is stored in advance in a table format in the information storage means as described in the first embodiment, and the information storage means is accessed so that the detection result of the roll diameter detection means 12 is obtained. The amount of decrease in the roll diameter of the corresponding feed roll 4a, that is, the wear amount of the feed roll 4a is obtained. When the information regarding the roll diameter variation is obtained, the speed variable means 10 then obtains coefficient information from the information storage means or a storage device accessible by the speed variable means 10 (S202). The acquisition of the coefficient information is the same as in the case of the first embodiment.

  Thereafter, as in the case of the first embodiment, the rotational speed of the feed roll 4a is determined (S203), and the determination result is output to the feed motor 9 (S204). As a result, the feed roll 4 a is driven at a rotational speed that matches the roll peripheral speed of the registration roll pair 5, and transports the paper 2 fed out by the pickup roll 3 toward the registration roll pair 5. Then, the sheet 2 is transported at the rotational speed until the rotation operation stop timing before the rear end of the sheet 2 passes the feed roll pair 4.

  As described above, also in the paper conveying apparatus described in the present embodiment, the speed variable means 10 makes the rotation speed of the feed roll 4a variable as in the case of the first embodiment. Even when the paper 4 and the registration roll pair 5 are arranged side by side on the paper conveyance path 6, it is possible to avoid the occurrence of a paper conveyance delay or a change in the conveyance speed relationship with the registration roll pair 5. Can do. Accordingly, it is possible to ensure the skew correction of the paper 2 while ensuring the miniaturization, the low power consumption, the low price, etc. of the copying machine or the printer device on which the paper transport device is mounted, and the image formation. This makes it possible to favorably form an image on the paper 2 while avoiding the deviation of the paper conveyance timing to the section.

  Further, according to the paper conveying apparatus described in the present embodiment, since the fluctuation of the roll diameter of the feed roll 4a is detected and the rotation speed of the feed roll 4a is varied based on the detection result, this actually occurs. The wear of the feed roll 4a is reflected in the variable speed result, and it is possible to accurately vary the rotational speed in order to ensure skew correction and avoid misalignment of the paper transport timing.

[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.

  The sheet conveying apparatus described here includes a speed detecting unit that detects the conveying speed of the sheet 2 by the feed roll pair 4. As the speed detection means, two sensors provided on the conveyance path 6 of the paper 2 from the feed roll pair 4 to the registration roll pair 5 are used. From the detection result of the paper 2 by each sensor and the difference between the detection timings, One configured to detect the conveyance speed of the sheet 2 can be cited. At this time, it is conceivable to use the feed sensor 7 and the registration sensor 8 as the two sensors. In addition, one sensor (for example, one of the feed sensor 7 or the registration sensor 8) provided on the conveyance path 6 of the sheet 2 from the feed roll pair 4 to the registration roll pair 5 is used, and the sensor and the conveyance are used. It may be configured to detect the conveyance speed of the paper 2 from the distance to a predetermined location on the path 6 (for example, in the paper feed tray 1) and the time required to convey the distance. .

  Since such a speed detection means is provided, in the paper conveying apparatus described in the present embodiment, the speed variable means 10 changes the rotation speed of the feed roll 4a based on the detection result by the speed detection means. It is like that. This “based on” is the same as the description in the first embodiment.

  Next, an example of processing operation when the speed variable unit 10 changes the rotation speed of the feed roll 4a in the sheet conveying apparatus configured as described above will be described. FIG. 6 is a flowchart showing an example of processing operation with variable rotation speed in the third embodiment. As shown in the figure, in the paper transport device, when there is a print start instruction, the following processing operation is performed.

  First, the speed variable means 10 obtains information on the conveyance speed of the paper 2 by the feed roll pair 4 from the detection result by the speed detection means (S301). Specifically, when the speed detection unit detects the transport speed of the sheet 2, the relationship between the transport speed and the roll diameter of the feed roll 4a is uniquely determined, and the corresponding relationship is determined according to the first or second embodiment. The amount of decrease in the roll diameter of the feed roll 4a corresponding to the detection result of the speed detection means by accessing the information storage means in advance in a table format stored in the information storage means as described in the embodiment, that is, The amount of wear of the feed roll 4a is obtained. When the information regarding the roll diameter variation is obtained, the speed variable means 10 then obtains coefficient information from the information storage means or a storage device accessible by the speed variable means 10 (S302). The acquisition of the coefficient information is the same as in the case of the first embodiment.

  Thereafter, as in the case of the first or second embodiment, the rotational speed of the feed roll 4a is determined (S303), and the determination result is output to the feed motor 9 (S304). As a result, the feed roll 4 a is driven at a rotational speed that matches the roll peripheral speed of the registration roll pair 5, and transports the paper 2 fed out by the pickup roll 3 toward the registration roll pair 5. Then, the sheet 2 is transported at the rotational speed until the rotation operation stop timing before the rear end of the sheet 2 passes the feed roll pair 4.

  As described above, also in the paper conveying apparatus described in the present embodiment, the speed variable unit 10 makes the rotation speed of the feed roll 4a variable as in the case of the first or second embodiment. 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 conveyance delay of the sheet 2 and the change in the conveyance speed relationship with the registration roll pair 5 may occur. It can be avoided. Accordingly, it is possible to ensure the skew correction of the paper 2 while ensuring the miniaturization, the low power consumption, the low price, etc. of the copying machine or the printer device on which the paper transport device is mounted, and the image formation. This makes it possible to favorably form an image on the paper 2 while avoiding the deviation of the paper conveyance timing to the section.

  Further, according to the paper transport device described in this embodiment, the transport speed of the paper 2 by the feed roll pair 4 is detected, and the rotational speed of the feed roll 4a is varied based on the detection result. The delay in the transport speed is reflected in the speed variable result, and it is possible to accurately vary the rotation speed in order to ensure skew correction and avoid misalignment of the paper transport timing. .

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

  The paper transport apparatus described here includes paper recognition means for recognizing the type of paper 2 transported by the feed roll pair 4. The type of paper 2 means at least one of paper quality (plain paper, recycled paper, OHP paper, etc.), paper thickness or size (A4, postcard size, etc.).

  In general, if the types of paper 2 are different, there is a possibility that the conveyance speed of the paper 2 will not be the same even if the feed roll 4a is rotated at the same rotational speed. For example, if the paper quality of the paper 2 is different, the friction coefficient with the feed roll 4a is different. Further, when the paper thickness of the paper 2 is different, the degree of elastic deformation of the feed roll 4a is affected, and as a result, the roll peripheral speed of the feed roll 4a is different. In addition, when the size of the paper 2 is different, the paper weight is also different, so that the load on the feed roll 4a is different. As described above, depending on the type of the paper 2, a difference occurs in the transport speed. Therefore, the paper transport device described here includes a paper recognition unit that recognizes the type of the paper 2.

  FIG. 7 is a schematic diagram showing a specific example of the paper recognition means. For example, as a paper recognizing means for recognizing the paper quality of the paper 2, as shown in FIG. 7A, the reflected light of the light irradiated on the uppermost paper 2 stored in the paper feed tray 1 is used. A reflection type paper quality detection sensor 13 for receiving light is provided, and the reflectance of the light received by the reflection type paper quality detection sensor 13 and the correspondence between the reflectance and the paper quality set in advance are set in the paper feed tray 1. One that determines the quality of the paper 2 is mentioned. For example, as a paper recognition means for recognizing the paper thickness of the paper 2, as shown in FIG. 7B, one axial position of the registration roll pair 5 sandwiching the paper 2 is the thickness of the paper 2. And a reflection type displacement sensor 14 for detecting the amount of movement, and detecting the thickness of the sheet 2 from the detection result of the reflection type displacement sensor 14. . For example, as a sheet recognition means for recognizing the size of the sheet 2, a size detection sensor 16 for detecting the position of the end guide 15 of the sheet 2 in the sheet feed tray 1 is used as shown in FIG. An example is provided that determines the size of the paper 2 from the detection result of the size detection sensor 16. The paper recognition means may be any means capable of recognizing at least one of paper quality, paper thickness, or size, but may be capable of recognizing two or more of these. Further, the paper recognition means is not necessarily limited to the specific configuration example shown in FIGS. 7A to 7C, but is set by the user on the operation panel of a copier, printer, or the like. Therefore, the type of the paper 2 may be recognized.

  In addition, such a paper recognizing unit is provided, and in the paper conveying apparatus described in the present embodiment, the speed variable unit 10 determines whether the rotation speed of the feed roll 4a is variable based on the recognition result by the paper recognizing unit. To do it. This “based on” is also the same as the description in the first to third embodiments. Specifically, when the speed variable unit 10 recognizes the type of the sheet 2 to be transported from the sheet recognition unit, the rotation speed of the feed roll 4a when transporting the sheet 2 at a desired transport speed with respect to the recognition result. Therefore, the correspondence relationship is stored in advance in the form of a table in the information storage means as described in the first to third embodiments, and the information storage means is accessed, so that the paper 2 The information regarding the rotational speed of the feed roll 4a corresponding to the type of recognition result is obtained. Next, coefficient information is also obtained as necessary. Thereafter, as in the first to third embodiments, the rotational speed of the feed roll 4 a is determined from the obtained information, and the determination result is output to the feed motor 9. Thereby, the feed roll 4a conveys the paper 2 toward the registration roll pair 5 at a desired conveyance speed regardless of the type of the paper 2. Then, the sheet 2 is conveyed at that speed until the rotation operation stop timing before the rear end of the sheet 2 passes through the feed roll pair 4.

  The desired conveyance speed described here may be determined as appropriate according to the configuration (conveyance distance, etc.) of the sheet conveying apparatus. As an example thereof, as described in the first to third embodiments. In addition, a speed that matches the transport speed of the sheet 2 by the registration roll pair 5 is exemplified.

  As described above, also in the sheet conveying apparatus described in the present embodiment, the speed variable unit 10 makes the rotation speed of the feed roll 4a variable as in the case of the first to third embodiments. 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 conveyance delay of the sheet 2 and the change in the conveyance speed relationship with the registration roll pair 5 may occur. It can be avoided. Accordingly, it is possible to ensure the skew correction of the paper 2 while ensuring the miniaturization, the low power consumption, the low price, etc. of the copying machine or the printer device on which the paper transport device is mounted, and the image formation. This makes it possible to favorably form an image on the paper 2 while avoiding the deviation of the paper conveyance timing to the section.

  Further, according to the paper transport apparatus described in the present embodiment, the type of the paper 2 transported by the feed roll pair 4 is recognized, and the rotational speed of the feed roll 4a is varied based on the recognition result. The paper 2 can be transported at a desired speed regardless of the type, and the rotational speed can be accurately varied in order to ensure skew correction and avoid misalignment of the paper transport timing. It becomes possible.

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

  In the first to fourth embodiments, the speed varying means 10 varies the rotational speed with respect to the feed roll 4a so that the roll peripheral speeds of the feed roll 4a and the registration roll pair 5 coincide with each other. The case where the conveyance speed is matched has been described as an example. If the rotational speed of the feed roll 4a is varied in this way, even when the paper 2 is nipped and conveyed by both the feed roll pair 4 and the registration roll pair 5, the respective conveyance speeds match. This is because the sheet 2 can be transported without stress or the like, thereby preventing an image formation defect due to, for example, a shift of the sheet transport timing to the image forming unit.

  However, the rotation speed variation of the feed roll 4a by the speed varying means 10 is not necessarily limited to the above-described aspect. Other aspects include the following. For example, the speed variable means 10 causes the sheet 2 to bend by causing the sheet 2 to abut against the registration roll pair 5 to perform skew correction, and when the registration roll pair 5 starts conveying the sheet 2, the sheet 2 is fed to the feed roll pair. 4 and the registration roll pair 5, it is necessary to reduce the stress on the paper 2 by appropriately changing the rotation speed of the feed roll 4 a. Thus, the rotational speed of the feed roll 4a is changed so that the bending loop generated in the paper 2 is canceled when the feed roll 4a is turned off. Specifically, the bending loop generated in the sheet 2 is a fixed amount and can be specified from the conveyance speed and the conveyance time by the registration roll pair 5 until the registration roll pair 5 abuts. Further, the timing for turning off the driving of the feed roll 4a can be specified in advance. Based on the information that can be specified in advance, when the registration roll pair 5 starts conveying the paper 2, the speed variable unit 10 slows the rotation speed of the feed roll 4 a compared to the registration roll pair 5, and The bending loop of the paper 2 is eliminated when the driving is turned off.

  If the rotation speed of the feed roll 4a is varied as described above, it is very suitable for reducing the stress or the like on the paper 2 when the drive of the feed roll 4a is turned off for the following reason. At the time when the drive of the feed roll 4a is turned off, it is usually necessary to prevent double feeding of the paper, so that the paper 2 is nipped (nip) between the feed roll pair 4. Then, the sheet 2 is conveyed to the registration roll pair 5 side by using the driving of the registration roll pair 5 and the action of a one-way clutch or a torque limiter attached to the feed roll pair 4. At this time, there is a gap between the drive-off timing of the feed roll 4a and the timing at which the bending loop of the paper 2 is eliminated, and if the bending loop is eliminated after the driving is turned off, the paper 2 is removed when the deflection loop is eliminated. There is a risk of impact loading. On the other hand, if the bending loop of the paper 2 is eliminated when the feed roll 4a is turned off, the impact load on the paper 2 can be reduced as much as possible, and as a result, to the image forming unit. Therefore, it is possible to prevent image formation defects due to deviations in the sheet conveyance timing.

[Sixth Embodiment]
Next, a sixth 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 to fifth embodiments described above is also omitted here.

  In the first to fifth embodiments, the speed variable means 10 changes the rotational speed with respect to the feed roll 4 a at a timing before the registration roll pair 5 starts nipping and conveying the paper 2 abutted against the registration roll pair 5. The case where it is performed has been described as an example. If the rotation speed is varied at such timing, when the sheet 2 is nipped and conveyed by both the feed roll pair 4 and the registration roll pair 5, the respective conveyance speeds are appropriately adjusted. This is because the conveyance can be performed without applying stress or the like, and thereby, for example, it is possible to prevent an image formation failure due to a deviation of the sheet conveyance timing to the image forming unit.

  However, the rotational speed timing of the feed roll 4a by the speed varying means 10 is not necessarily limited to the above-described aspect. Other aspects include the following. For example, the speed variable means 10 changes the rotation speed with respect to the feed roll 4 a at a timing before the feed roll pair 4 transports the paper 2 fed out from the paper feed tray 1 and hits the registration roll pair 5.

  If the rotation speed is varied at such timing, not only when the paper 2 is nipped and conveyed by both the feed roll pair 4 and the registration roll pair 5, but also the paper 2 fed out from the paper feed tray 1 is fed to the feed roll. Even when the pair 4 is transported, the transport speed by the feed roll pair 4 is appropriately adjusted. Therefore, for example, even when the feed roll 4a is worn and the roll diameter is reduced, the amount of the flex loop when the flex loop is generated in the paper 2 by abutting against the registration roll pair 5 is kept constant. It becomes possible. This is very suitable for preventing a skew correction problem associated with a conveyance delay of the sheet 2. That is, the skew correction of the paper 2 can be ensured, and the occurrence of image formation defects in the image forming unit can be effectively prevented. Furthermore, this is very effective in realizing the fifth embodiment described above, and is effective in shortening the time required for paper conveyance and skew correction.

  In the above-described first to sixth embodiments, preferred specific examples of the present invention have been described. However, the present invention is not limited to the contents described in each embodiment, and the gist of the present invention is described. Changes can be made as appropriate without departing from the scope, and for example, the contents described in the first to sixth embodiments can be combined as appropriate.

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 explanatory drawing which shows a specific example of the information regarding the secular variation of the roll diameter in the 1st Embodiment of this invention. It is a flowchart which shows the processing operation example of variable rotational speed in the 1st Embodiment of 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. It is a flowchart which shows the processing operation example of variable rotational speed in the 2nd Embodiment of this invention. It is a flowchart which shows the processing operation example of variable rotational speed in the 3rd Embodiment of this invention. It is a schematic diagram which shows the specific example of the paper recognition means in 4th 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, 4a ... Feed roll, 4b ... Retard roll, 5 ... Regist roll pair, 6 ... Conveyance path, 9 ... Feed motor, 10 ... Variable speed Means, 11 ... Information storage means, 12 ... Roll diameter detection means, 13 ... Reflection type paper quality detection sensor, 14 ... Reflection type displacement sensor, 16 ... Size detection sensor

Claims (9)

A pair of feed rolls consisting of a feed roll and a retard roll that conveys the paper fed from the paper feed tray every leaf, and the paper is operated at a predetermined timing after correcting the skew of the paper by abutting the paper. A pair of registration rolls that sandwich and convey the sheet to the rear side, and the pair of feed rolls and the pair of registration rolls are arranged side by side on the sheet conveyance path,
A sheet conveying apparatus comprising: a speed varying unit configured to vary a rotation speed of the feed roll. While comprising information storage means for storing information on secular variation of the roll diameter of the feed roll,
The sheet conveying apparatus according to claim 1, wherein the speed varying unit varies the rotation speed of the feed roll based on information stored in the information storage unit. While equipped with a roll diameter detection means for detecting the fluctuation of the roll diameter of the feed roll,
The sheet conveying apparatus according to claim 1, wherein the speed varying unit varies a rotation speed of the feed roll based on a detection result by the roll diameter detecting unit. A speed detecting means for detecting a transport speed of the paper by the feed roll pair;
The sheet conveying apparatus according to claim 1, wherein the speed varying unit varies a rotation speed of the feed roll based on a detection result by the speed detecting unit. A sheet recognizing unit for recognizing the type of the sheet conveyed by the feed roll pair;
The sheet conveying apparatus according to claim 1, wherein the speed varying unit varies a rotation speed of the feed roll based on a recognition result by the sheet recognizing unit. The said speed variable means makes the roll peripheral speed of the said feed roll and the said registration roll pair correspond by the variable of the rotational speed with respect to the said feed roll. The any one of Claims 1-5 characterized by the above-mentioned. Paper transport device. The speed variable means is such that the deflection loop of the paper caused by the abutting against the pair of registration rolls is canceled when the feed roll is turned off to drive the paper. The sheet conveying device according to any one of claims 1 to 5, wherein the rotation speed of the feed roll is varied. The speed variable unit is configured to change the rotational speed of the feed roll at a timing before the registration roll pair starts to nipping and conveying the paper abutted against the registration roll pair. Item 8. The sheet conveying apparatus according to any one of Items 1 to 7. The speed variable means changes the rotational speed with respect to the feed roll at a timing before the feed roll pair transports the paper fed from the paper feed tray and hits the registration roll pair. The sheet conveying apparatus according to claim 1, wherein

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