JP2019026407A - Sheet feeder - Google Patents

Abstract

To reduce a collision sound by a register roller when a leading edge of a sheet strikes a skew feeding correction portion without the deterioration in productivity of a printed product, even if there are variations in a sheet conveyance amount at an initial stage of feeding from a sheet feed table.SOLUTION: On the basis of a timing at which a register sensor 19 detects a leading edge of a sheet P being delivered from a sheet feed table 11 by a sheet feed unit 5 and conveyed along a conveyance path R, a control unit 4 determines a time T1 from the timing to a start time of a deceleration section ending when the sheet P arrives at a constant-speed transition point C. Also, on the basis of a timing at which the register sensor 19 detects the leading edge of the sheet P, the control unit 4 determines a time T2 indicating a length of a V2 (low speed) section following the deceleration section and low speeds V2 (V2a, V2b, V2c) which are conveying speeds of the sheet P in the V2 (low speed) section.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a paper feeding device that feeds paper.

  2. Description of the Related Art Conventionally, in a printing apparatus such as an ink jet printer or a stencil printing apparatus, a paper feeding apparatus that sends out paper from a paper feeding table and conveys it to a printing unit is known. In such a sheet feeding device, the sheet feeding unit feeds the sheets on the sheet feeding table one by one to the registration roller. The fed sheet hits the resist roller in a stopped state and temporarily stops.

  After the paper hits the registration roller, the paper feed unit continues to feed the paper to the registration roller for a certain period. Accordingly, a slack is formed on the sheet between the sheet feeding unit and the registration roller until the sheet feeding unit stops feeding the sheet. This slack corrects the skew of the paper, and the paper after the skew correction is sent to the printing unit when the rotation of the registration roller starts.

  In addition, after the paper feeding unit stops feeding the paper, the registration roller starts to rotate in synchronization with the image forming operation by the image forming unit, so that an image is formed at an appropriate position of the paper in the image forming unit.

  In this type of paper feeding device, the sound generated when the paper hits the registration roller tends to increase as the paper transport speed increases. Therefore, immediately before the sheet hits the registration roller, the sheet conveyance speed by the sheet feeding unit is reduced to reduce the collision noise.

  Specifically, when the registration sensor placed in front of the registration roller detects the paper, the paper conveyance speed is reduced until the paper reaches the registration roller, and when it hits the registration roller, the paper is conveyed at a low speed. A slack is stably formed on the sheet until the registration roller starts to rotate (for example, Patent Document 1).

Japanese Patent Laid-Open No. 2005-219895

  By the way, when the paper feed unit feeds paper one by one from the paper feed tray, the amount of paper transport at the beginning of feeding varies due to the slippage variation that occurs between the paper on the paper feed tray and the feed roller. May occur.

  If the transport amount of the paper at the initial feeding stage varies, the timing at which the paper hits the registration roller and the timing at which the slack required for the paper hitting the registration roller is also varied. For this reason, even when the amount of paper transport at the initial stage of feeding is the smallest, even if sagging necessary for the paper hitting the registration roller is formed before the rotation of the registration roller starts, even at the expense of the productivity of the printed matter. It is necessary to delay the timing for starting the rotation of the registration roller.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the sheet collision speed in the skew feeding correction portion by reducing the sheet conveyance speed before the skew feeding correction portion by the registration roller. An object of the present invention is to provide a paper feeding device capable of reducing the collision noise of a paper against a skew feeding correction unit without deteriorating the productivity of printed matter even if there is a variation in the amount of paper conveyed at the initial stage of feeding from the paper feeding table. is there.

In order to achieve the above object, a paper feeding device according to one aspect of the present invention includes:
Based on the timing at which the detection unit detects the paper before the skew correction unit that corrects the skew of the paper fed by the paper feed unit and sends it to the image forming unit, the detection unit and the skew correction unit In the paper feeding device that decelerates the paper conveyance speed by the paper feeding unit at a predetermined position between them to a constant speed lower than that before detection of the paper by the detection unit,
Based on the length of time from the start of paper feed by the paper feed unit to the detection of paper by the detection unit, the start of a deceleration section that decelerates the paper transport speed at the end of arrival of the paper at the predetermined location A deceleration pattern determination unit that determines a deceleration pattern including a time point;
A deceleration control unit that decelerates the sheet conveyance speed by the sheet feeding unit to the constant conveyance speed by the deceleration pattern determined by the deceleration pattern determination unit;
Is provided.

  According to the present invention, when the sheet conveyance speed is reduced before the skew correction unit to reduce the sheet collision sound in the skew correction unit, there is a variation in the sheet conveyance amount at the initial stage of feeding from the sheet feeding table. Even in such a case, it is possible to reduce the collision sound of the sheet against the skew feeding correction unit without reducing the productivity of the printed matter.

It is explanatory drawing which shows schematic structure of a printing apparatus provided with the paper feeder which concerns on one Embodiment of this invention. FIG. 2 is a block diagram illustrating a configuration of a control system of the printing apparatus illustrated in FIG. 1. It is explanatory drawing which shows schematic structure of the paper feed part shown in FIG. (A) is explanatory drawing which shows the outline | summary of the drive control of the paper feed part which the control part shown in FIG. 1 performs, (b) is explanatory drawing which shows the drive control content by the control part for every conveyance rate of a paper. 1A and 1B show a change in paper conveyance speed from paper feeding by the paper feeding unit shown in FIG. 1 to the start of rotation of the registration roller. FIG. 1A is a graph when the paper detection timing by the registration sensor is late, and FIG. It is a graph when the detection timing of the sheet by the registration sensor is early. 3 is a flowchart illustrating a procedure of processing related to primary paper feeding performed by a control unit illustrated in FIG. 1.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Throughout the drawings, the same or equivalent parts and components are denoted by the same or equivalent reference numerals. However, it should be noted that the drawings are schematic and different from the actual ones. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiment described below exemplifies an apparatus or the like for embodying the technical idea of the present invention, and the technical idea of the present invention is to arrange the components and the like as follows. It is not something specific. The technical idea of the present invention can be variously modified within the scope of the claims.

  FIG. 1 is an explanatory diagram illustrating a schematic configuration of a printing apparatus including a paper feeding device according to an embodiment of the present invention, and FIG. 2 is a block diagram illustrating a configuration of a control system of the printing apparatus illustrated in FIG. In the following description, the paper surface direction of FIG. Moreover, as shown in FIG. 1, when viewed from the user, the top, bottom, left, and right are defined as the top, bottom, left and right directions. Further, the path indicated by the thick line in FIG. 1 is a transport path R along which the paper P, which is a print medium, is transported. In the following description, upstream and downstream mean upstream and downstream in the transport path R, respectively.

  As shown in FIG. 1, the printing apparatus 1 includes a paper transport unit 2 and a printing unit 3. As illustrated in FIG. 2, the printing apparatus 1 further includes a control unit 4 that controls the operations of the paper transport unit 2 and the printing unit 3.

  The paper transport unit 2 includes a paper feed unit 5, a skew correction unit 6, and a detection unit 7.

  The paper feeding unit 5 feeds the paper P to the printing unit 3. As shown in FIG. 1, the paper supply unit 5 includes a paper supply table 11, a paper supply roller 12, and an intermediate conveyance roller 15. As shown in FIG. 2, the paper transport unit 2 further includes a paper feed motor 14 and an intermediate transport motor 16.

  A paper feed tray 11 shown in FIG. 1 is a stack of paper P used for printing, and a paper feed roller 12 is disposed on the upper side thereof. FIG. 3 is an explanatory diagram showing a schematic configuration of the paper transport unit 2. In FIG. 3, the illustration of the intermediate conveyance roller 15 portion of the conveyance path R is omitted.

  As shown in FIG. 3, the paper feed roller 12 has a scraper roller 12a and a pickup roller 12b. The scraper roller 12 a comes into contact with the uppermost part of the paper P stacked on the paper feed tray 11 and rotates to feed the paper P from the paper feed tray 11. The pickup roller 12b picks up the paper P sent from the paper feed tray 11 by the scraper roller 12a one by one in cooperation with the scooping plate 12c, and sends it out to the transport path R.

  The paper feed roller 12 is rotated by the paper feed motor 14 shown in FIG. Specifically, the paper feed motor 14 rotates the scraper roller 12a and the pickup roller 12b in FIG. 3 in which a timing belt (not shown) is spanned between the shafts in synchronization. The paper feed motor 14 is connected to the scraper roller 12a and the pickup roller 12b by a one-way clutch (not shown). This one-way clutch transmits only the rotation in the direction of feeding the paper P to the transport path R side from the paper feed motor 14 to the scraper roller 12a and the pickup roller 12b.

  A pair of intermediate conveyance rollers 15 shown in FIG. Both intermediate transport rollers 15 nip the leading edge of the sheet P being fed from the paper feed tray 11 to the transport path R by the paper feed rollers 12 (scraper roller 12a and pickup roller 12b), and register downstream of the transport path R. Send to roller 17. One of the intermediate conveyance rollers 15 is rotated by the intermediate conveyance motor 16 in FIG.

  In the present embodiment, for ease of explanation, a case will be described in which the paper feed unit 5 has one set of the paper feed table 11, the paper feed roller 12, and the intermediate transport roller 15. However, the present invention is also applicable to the case where the paper feed unit 5 has a plurality of sets of the paper feed tray 11, the paper feed rollers 12, and the intermediate transport rollers 15.

  The skew correction unit 6 corrects the skew of the paper P fed to the printing unit 3 by the paper feeding unit 5 and sends the paper P to the printing unit 3 in accordance with the image formation timing in the printing unit 3. The skew correction unit 6 includes a registration roller 17 and a registration motor 18 shown in FIG.

  The registration roller 17 shown in FIG. 1 is arranged on the downstream side of the intermediate conveyance roller 15. The registration roller 17 temporarily stops the paper P transported by the intermediate transport roller 15, and after the slack is formed on the paper P, transports it to the printing unit 3. The registration roller 17 is rotated by a registration motor 18 in FIG.

  The detection unit 7 shown in FIG. 1 detects the paper P at a detection location D on the upstream side of the registration roller 17. The detection unit 7 includes a registration sensor 19.

  The registration sensor 19 (corresponding to the detection unit in the claims) outputs a detection signal to the control unit 4 when the paper P is detected at the detection location D. The registration sensor 19 includes an optical sensor having a light emitting element and a light receiving element.

  The printing unit 3 shown in FIG. 1 performs printing on the paper P while conveying the fed paper P. The printing unit 3 is disposed on the downstream side of the paper transport unit 2. In this embodiment, the printing unit 3 includes a belt conveyance unit 21 and an inkjet head unit 22.

  The belt transport unit 21 transports the sheet P transported by the registration rollers 17 while being sucked and held on the belt. The roller on which the belt of the belt conveyance unit 21 is wound is driven by a motor (not shown), so that the belt rotates and the paper P on the belt is conveyed.

  The inkjet head unit 22 is disposed above the belt conveyance unit 21. The inkjet head unit 22 includes a plurality of line-type inkjet heads in which a plurality of nozzles are arranged in a direction (front-rear direction) substantially orthogonal to the transport direction of the paper P. The inkjet head unit 22 prints an image by ejecting ink from the inkjet head onto the paper P conveyed by the belt conveyance unit 21.

  The control unit 4 controls the operation of each unit of the printing apparatus 1. The control unit 4 includes a CPU, a RAM, a ROM, and the like.

  Specifically, the control unit 4 feeds the paper P to the printing unit 3 by the paper feeding unit 5 of the paper transport unit 2, and transports the paper P by the belt transport unit 21 in the printing unit 3, while Control is performed so that ink is ejected by 22 to print on the paper P.

  In the sheet feeding operation to the registration roller 17 by the intermediate conveyance roller 15 of the sheet feeding unit 5, the control unit 4 determines the amount of sag specified on the leading end side of the sheet P when the sheet P conveyed by the intermediate conveyance roller 15 hits the registration roller 17. When the slack is formed, the intermediate conveyance roller 15 is decelerated and stopped, and then the registration roller 17 is driven.

  The control unit 4 controls the driving of the paper feed motor 14 based on the detection of the paper P by the registration sensor 19.

  FIG. 4A is an explanatory diagram illustrating an outline of drive control of the paper feeding unit performed by the control unit 4, and FIG. 4B is an explanatory diagram illustrating drive control content by the control unit 4 for each sheet conveyance rate. In these drawings, the horizontal axis of the bar graphs indicates the transport distance of the paper P from the paper feed tray 11.

  However, the portion on the right side of the drawing with respect to the registration roller 17 indicates the conveyance amount of the sheet P by the intermediate conveyance roller 15 after the leading end of the sheet P hits the stopped registration roller 17.

  The control unit 4 shown in FIG. 2 performs control of causing the paper transport unit 2 to transport the paper P from the paper feed table 11 to the printing unit 3 when a print job is generated. At that time, the control unit 4 first drives the paper feed motor 14 of the paper feed unit 5 to move the paper feed roller 12 (scraper roller 12a and pickup roller 12b) in the direction in which the paper P is sent out from the paper feed table 11. Rotate.

  At that time, the control unit 4 until the rotational speed of the paper feed roller 12 (the scraper roller 12a and the pickup roller 12b) reaches a predetermined speed V1 corresponding to the transport speed of the paper P in the acceleration section of FIG. Then, the rotation speed of the paper feed motor 14 is accelerated for a certain time. When this acceleration is completed, the control unit 4 rotates the paper feed motor 14 at a constant speed so that the conveyance speed of the paper P is maintained at the predetermined speed V1 in the V1 (high speed) section of FIG.

  While the control of the V1 (high speed) section is performed by the control unit 4, the leading edge of the paper P sent out by the paper feed roller 12 reaches the intermediate transport roller 15 and is nipped. Therefore, the control unit 4 accelerates the rotational speed of the intermediate transport motor 16 in advance to a speed at which the intermediate transport roller 15 transports the paper P at the same predetermined speed V1 as that of the paper feed roller 12. Accordingly, the paper P nipped by the intermediate conveyance roller 15 is conveyed to the registration roller 17 side by the intermediate conveyance roller 15 at a predetermined speed V1.

  Further, when the paper P is nipped by the intermediate transport roller 15, it is not necessary to feed the paper P by the paper feed roller 12 (the scraper roller 12a and the pickup roller 12b). Therefore, the control unit 4 controls to rotate the paper feed motor 14 at the timing after the leading edge of the paper P that has passed through the paper feed roller 12 (the scraper roller 12a and the pickup roller 12b) is nipped by the intermediate transport roller 15, for example. Exit.

  When the control unit 4 finishes the control of rotating the paper feed motor 14, the paper feed roller 12 (the scraper roller 12a and the pickup roller 12b) is moved by the intermediate transport roller 15 to the registration roller 17 side until the rear end of the paper P passes. The paper P is rotated by the paper P and is rotated.

  This driven rotation is continued until the trailing edge of the paper P passes through the pickup roller 12b of the paper feed roller 12. The rotation of the paper feed roller 12 (the scraper roller 12a and the pickup roller 12b) after the paper P passes is stopped by a load applied to the paper feed roller 12.

  When the leading edge of the sheet P conveyed to the registration roller 17 side by the intermediate conveyance roller 15 is detected by the registration sensor 19, the control unit 4 starts the deceleration point (V1 (high speed) in FIG. 4A). Determine the end point of the section. This deceleration section ends when the paper is conveyed to a position where the leading edge of the paper P passes the registration sensor 19 and reaches a certain distance before the registration roller 17.

  When the start point of the deceleration zone is determined, the control unit 4 keeps the conveyance speed of the paper P constant until the leading edge of the paper P reaches a certain distance before the registration roller 17 after the deceleration zone ends. Decelerate with acceleration. By this deceleration, the conveyance speed of the paper P is decelerated to a constant low speed V2 that is lower than the predetermined speed V1 at the end point of the deceleration section. When the deceleration section ends, the control unit 4 rotates the intermediate transport motor 16 at a constant speed so that the transport speed of the paper P is maintained at the low speed V2 in the V2 (low speed) section of FIG.

  While the control of the V2 (low speed) section is performed by the control unit 4, the leading edge of the sheet P sent out by the intermediate conveyance roller 15 reaches the registration roller 17 and is abutted against it. When the sheet P is abutted against the registration roller 17, a slack for skew correction is formed on the leading end side of the sheet P due to the subsequent rotation of the intermediate conveyance roller 15. Therefore, the control unit 4 ends the control of rotating the intermediate conveyance motor 16 at a timing after the leading edge of the paper P hits the registration roller 17 and before the registration roller 17 starts to rotate.

  For this purpose, when the registration sensor 19 detects the leading edge of the paper P, the control unit 4 starts a stop section in which the transport speed of the paper P by the intermediate transport roller 15 is reduced from the low speed V2 to zero (stop) ( V2 (low speed) section end time) is determined.

  When the start time of the stop section is determined, the control unit 4 reduces the transport speed of the paper P at a constant acceleration until the stop section ends and the rotation of the intermediate transport roller 15 stops. By this deceleration, the conveyance speed of the paper P becomes zero at the end point of the stop section. When this stop section ends, the control unit 4 ends the control for one cycle related to the conveyance of the paper P.

  By the way, when the paper P on the paper feed tray 11 is fed one by one by the paper feed roller 12 (scraper roller 12a and pickup roller 12b) in FIG. 2, it is sent out by slipping between the paper feed roller 12 and the paper P or the like. The time it takes may vary.

  If the slip generated between the paper feed roller 12 and the paper P on the paper feed tray 11 varies, the transport amount of the paper P at the initial stage of feeding from the paper feed tray 11 varies. Then, for example, the distance in which the paper P is conveyed in the acceleration section of FIG.

  If the paper P is transported after the V1 (high speed) section without considering the variation in the transport distance of the paper P in the acceleration section, the timing at which the leading edge of the paper P hits the registration roller 17 or the registration roller 17 is hit. Variations also occur in the timing at which the slack required for the sheet P is formed.

  In that case, even when the transport amount of the paper P at the initial delivery is small and the timing at which the leading edge of the paper P hits the registration roller 17 is slow, the paper P hits the registration roller 17 before the registration roller 17 starts rotating. In order to form the necessary slack, the rotation start of the registration roller 17 must be delayed even at the expense of the productivity of the printed matter.

  Therefore, in the present embodiment, the control unit 4 is required to detect when the registration sensor 19 detects the leading edge of the paper P, that is, until the leading edge of the paper P reaches the registration sensor 19 after the paper P is sent out from the paper feed tray 11. Based on the time, the conveyance pattern of the paper P after the V1 (high speed) section is determined.

  Note that the paper P that takes time to transport from the paper feed tray 11 to the registration sensor 19 has a shorter transport distance in the acceleration section of FIG. 4A than the paper P that does not take much time.

  Therefore, the control unit 4 determines a conveyance pattern for absorbing the variation in the conveyance distance of the paper P in the acceleration section of FIG. 4A during the conveyance of the paper P in the V1 (high speed) section and thereafter. In this transport pattern, the start time of the deceleration section (end time of the V1 (high speed) section) and the start time of the stop section (end time of the V2 (low speed) section) according to the transport distance of the paper P in the acceleration section. included.

  For example, as shown in the explanatory diagram of FIG. 4B, when there is a lot of slip between the paper P fed from the paper feed tray 11 and the paper feed roller 12, and the conveyance rate at the initial stage of feeding the paper P is low, the acceleration section The transport distance of the paper P at the time becomes shorter. In this case, it is necessary to increase the transport distance of the paper P after the V1 (high speed) section so as to compensate for the shortage of the transport distance in the acceleration section.

  Further, when the conveyance rate at the initial stage of feeding the paper P is low, as shown in the graph of FIG. 5A, the paper P fed from the paper feed table 11 is fed in the acceleration section and the V1 (high speed) section. The time Ta required to be transported by the paper roller 12 or the intermediate transport roller 15 and detected by the registration sensor 19 becomes longer.

  In this case, the remaining time (Td−Ta) from the detection of the paper P by the registration sensor 19 to the start of the rotation of the registration roller 17 is shortened. For this reason, the primary feeding of the paper P to the registration roller 17 by the paper feeding unit 5 from the time when the paper P on the paper feed tray 11 is sent to the time when the conveyance of the paper P by the intermediate transport roller 15 is stopped (time Tc). Is completed before the rotation of the registration roller 17 is started, it is necessary to shorten the V2 (low speed) section as much as possible.

  Therefore, as shown in FIG. 4B, the control unit 4 increases the transport distance of the paper P in the V1 (high speed) section by delaying the start time of the deceleration section as much as possible to lengthen the V1 (high speed) section. I try to earn. In addition, the control unit 4 shortens the deceleration zone by delaying the start point of the deceleration zone as much as possible.

  Note that if the start point of the deceleration zone is delayed, the deceleration zone is shortened, so that the reduction width of the conveyance speed of the paper P that is decelerated at a constant acceleration during the deceleration zone is reduced. Then, the conveyance speed (low speed (V2c)) of the paper P in the V2 (low speed) section that shifts after the deceleration section ends is increased. Therefore, the control unit 4 starts the deceleration toward zero of the conveyance speed (low speed (V2c)) of the paper P as early as possible at the start point of the stop section.

  On the other hand, when there is little slip between the paper P fed from the paper feed tray 11 and the paper feed roller 12 and the transport rate at the initial stage of paper P delivery is high, the transport distance of the paper P in the acceleration section becomes long. In this case, since the transport distance of the paper P is earned in the acceleration section, the transport distance of the paper P after the V1 (high speed) section may be short.

  Further, when the conveyance rate at the initial stage of feeding the paper P is high, as shown in the graph of FIG. 5B, the paper P sent from the paper feed table 11 is fed in the acceleration section and the V1 (high speed) section. A time Ta required to be detected by the registration sensor 19 after being transported by the paper roller 12 or the intermediate transport roller 15 is shortened.

  In this case, the remaining time (Td−Ta) from the detection of the paper P by the registration sensor 19 to the start of the rotation of the registration roller 17 becomes longer. For this reason, even if the V2 (low speed) section is lengthened, the primary paper feeding (time Tc) of the paper P to the registration roller 17 by the paper feeding unit 5 can be finished before the rotation of the registration roller 17 is started.

  Therefore, as shown in FIG. 4B, the control unit 4 increases the speed of the deceleration section by advancing the start time of the deceleration section as much as possible, and transports the paper P that is decelerated at a constant acceleration during the deceleration section. The speed reduction range is increased.

  In addition, when the deceleration width of the conveyance speed of the paper P in the deceleration section increases, the conveyance speed (low speed (V2a)) of the paper P in the V2 (low speed) section that shifts after the deceleration section ends. Then, the amount of deceleration required to stop the intermediate transport roller 15 in the stop section is reduced. Therefore, the control unit 4 delays the start point of the stop section as much as possible, and starts to decelerate the conveyance speed (low speed (V2a)) of the paper P toward zero.

  When the slip between the paper P sent out from the paper feed tray 11 and the paper feed roller 12 is standard, and the transport rate at the initial stage of feeding the paper P is a medium level, the transport distance of the paper P in the acceleration section is standard. Length. In this case, since the transport distance of the paper P in the acceleration section is a standard distance, the transport distance of the paper P after the V1 (high speed) section may be a standard distance.

  Therefore, as shown in FIG. 4B, the control unit 4 sets the deceleration zone to a standard length by decelerating at a constant acceleration during the deceleration zone by setting the start point of the deceleration zone as a normal timing. The speed reduction width of the transport speed of the paper P to be used is a standard speed reduction width.

  In addition, since the deceleration width of the conveyance speed of the paper P in the deceleration section is a standard deceleration width, the conveyance speed (low speed (V2b)) of the paper P in the V2 (low speed) section that shifts after the deceleration section is finished. Standard speed. For this reason, the amount of deceleration required to stop the intermediate conveyance roller 15 in the stop section is also a standard amount. Therefore, the control unit 4 starts the deceleration toward the zero of the conveyance speed (low speed (V2b)) of the paper P at the normal timing with the start time of the stop section as the normal timing.

  Control of the control part 4 demonstrated above is implement | achieved when CPU of the control part 4 runs the program memorize | stored in ROM. Hereinafter, a procedure of processing related to the primary paper feeding from the feeding of the paper P from the paper feed tray 11 to the registration roller 17 after the control unit 4 stops feeding will be described with reference to the flowchart of FIG. .

  First, the CPU of the control unit 4 causes the paper feed roller 12 of the paper feed unit 5 to pick up the paper P on the paper feed tray 11 one by one (step S1), and sets the transport speed of the paper P by the paper feed roller 12 for a certain time. Accelerate at a constant acceleration over a period of time (step S3).

  Then, the CPU starts a V1 (high speed) section in which the paper P is transported at a constant speed V1 (high speed) by the paper feed roller 12 and the intermediate transport roller 15 (step S5), and then the registration sensor 19 detects the leading edge of the paper P. Is detected (step S7).

  If the paper P is not detected (NO in step S7), step S7 is repeated until it is detected. When the paper P is detected (YES in step S7), the CPU determines times T1 and T2 and a low speed V2 (step S9).

  Here, the low speed V2 is a transport speed of the paper P in the V2 (low speed) section in which the paper P is abutted against the registration roller 17. The low speed (V2a), the low speed (V2b), and the low speed (V2c) shown in FIG. 4B all correspond to the low speed V2 determined in step S9.

  The time T1 is the time from when the registration sensor 19 detects the leading edge of the paper P to when the V1 (high speed) section is finished. That is, the time T1 is a variable that defines the start point of the deceleration zone that follows the V1 (high speed) zone.

  The time T2 is a time indicating the length of the V2 (low speed) section. The start time of the V2 (low speed) section (end of the deceleration section) is the time when the leading edge of the paper P reaches the constant speed transition point C between the registration sensor 19 and the registration roller 17 (see FIGS. 1 and 3). End with.

  This constant speed transition portion C (corresponding to a predetermined portion in the claims) is a fixed position immediately before the paper P is abutted against the registration roller 17. Therefore, the time T2 is a variable that defines the start time of the stop section that follows the V2 (low speed) section.

  The arrival time of the paper P at the constant speed transition point C can be obtained by calculation from the time when the registration sensor 19 detects the leading edge of the paper P and the low speed V2 determined based on the detection time.

  When the times T1 and T2 and the low speed V2 are determined in step S9, the CPU checks whether or not the time T1 has elapsed since the registration sensor 19 detected the leading edge of the paper P (step S11).

  If the time T1 has not elapsed since the paper P was detected (NO in step S11), step S11 is repeated until the time has elapsed. If the time T1 has elapsed (YES in step S11), the CPU starts a decelerating section of the conveyance speed of the paper P by the intermediate conveyance roller 15 (step S13).

  Subsequently, the CPU confirms whether or not it is the time when the leading edge of the paper P reaches the constant speed transition point C (step S15). If the constant speed transition point C has not been reached (NO in step S15), step S15 is repeated until it reaches.

  If the constant speed transition point C has been reached (YES in step S15), the intermediate transport roller 15 starts a V2 (low speed) section in which the paper P is transported at a constant speed V2 (step S17). It is confirmed whether or not the time T2 has elapsed (step S19).

  If time T2 has not elapsed since the start of the V2 (low speed) section (NO in step S19), step S19 is repeated until the time has elapsed. When the time T2 has elapsed from the start of the V2 (low speed) section (YES in step S19), the CPU starts a stop section for transporting the paper P by the intermediate transport roller 15 (step S21).

  Subsequently, the CPU confirms whether or not the conveyance stop period of the paper P has ended (step S23). The end of the stop section is that the paper P is first fed to the registration roller 17 by the paper feeding unit 5 from the time when the paper P on the paper feed tray 11 is sent to the time when the conveyance of the paper P by the intermediate transport roller 15 is stopped. This can be confirmed when the time Tc required for the paper has elapsed.

  If the stop section has not ended (NO in step S23), step S23 is repeated until the stop section ends. If the stop section is completed (YES in step S23), a series of processes related to the primary sheet feeding of the sheet P to the registration roller 17 by the sheet feeding unit 5 is terminated.

  As is apparent from the above description, in the present embodiment, step S9 in the flowchart of FIG. 6 is processing corresponding to the deceleration pattern determination unit and the stop pattern determination unit in the claims. Moreover, in this embodiment, step S11 thru | or step S21 in FIG. 6 are the processes corresponding to the deceleration control part in a claim. Furthermore, in this embodiment, step S21 and step S23 in FIG. 6 are processing corresponding to the stop control unit in the claims.

  According to the sheet feeding device of the present embodiment described above, the control unit 4 causes the registration sensor 19 to detect the leading edge of the sheet P that is fed from the sheet feeding table 11 by the sheet feeding unit 5 and is transported through the transport path R. Based on the detected timing, the time T1 from that timing to the start of the deceleration section that ends when the paper P reaches the constant speed transition point C is determined.

  Further, according to the sheet feeding device of the present embodiment, the control unit 4 indicates the time T2 indicating the length of the V2 (low speed) section following the deceleration section based on the timing when the registration sensor 19 detects the leading edge of the sheet P. And the low speed V2 (V2a, V2b, V2c), which is the conveyance speed of the paper P in the V2 (low speed) section, is determined.

  For this reason, for example, the sheet conveyance amount at the initial stage of feeding of the sheet P by the sheet feeding unit 5 is large, the conveyance speed of the sheet P whose leading edge is detected by the registration sensor 19 at an early timing, and the timing at which the registration sensor 19 is late in the deceleration section. Thus, it is possible to decelerate the paper P for a longer period than the paper P from which the leading edge is detected.

  Therefore, the conveyance speed of the paper P can be further reduced until the post-decelerated paper P is abutted against the registration roller 17, and the impact sound when the paper P strikes the registration roller 17 can be further reduced. .

  Further, for example, the sheet transport amount at the initial stage of feeding of the sheet P by the sheet feeding unit 5 is small, and the sheet detected by the registration sensor 19 at an early timing is a deceleration zone of the sheet P transport speed detected by the registration sensor 19 at a later timing. Starting at a point later than P, the period during which the sheet P is conveyed at the predetermined speed V1 in the V1 (high speed) section before the shift to the deceleration section can be lengthened.

  Therefore, even if the conveyance speed of the paper P is lowered to the low speed V2 in the deceleration section before the paper P hits the registration roller 17 in order to reduce the impact sound when the paper P hits the registration roller 17, the registration roller 17 removes the paper P. It is possible to cause the sheet P to reach the registration roller 17 before starting to rotate at a pace sufficient for skew correction.

  From the above, according to the paper feeding device of this embodiment, when the conveyance speed of the paper P is decelerated in front of the registration rollers 17 to reduce the collision noise of the paper P on the registration rollers 17, Even if there is a variation in the sheet conveyance amount at the initial stage of feeding, the collision noise of the sheet P against the registration roller 17 can be reduced without reducing the productivity of printed matter.

  In this embodiment, the time T1, T2 when the control unit 4 determines the time point when the V2 (low speed) section is ended and the stop section is started based on the timing at which the registration sensor 19 detects the leading edge of the paper P. , Determined according to the low speed V2. However, whether or not to determine the start point of the stop section is arbitrary.

  In the present embodiment, when the control unit 4 determines the time T1 for determining the start point of the deceleration section based on the timing when the registration sensor 19 detects the leading edge of the paper P, the time T2 of the V2 (low speed) section is determined. Was further determined. However, whether or not to determine the time T2 of the V2 (low speed) section is arbitrary.

  Further, in the present embodiment, the case where the paper feed roller 12 includes the scraper roller 12a and the pickup roller 12b has been described, but the present invention is also applicable to the case where the paper feed roller 12 is configured by a single roller. Is applicable.

  In the present embodiment, the case where the paper feeding unit 5 includes the paper feeding roller 12 and the intermediate conveyance roller 15 has been described. However, the present invention can be applied to a paper feeding apparatus having the configuration in which the intermediate conveyance roller 15 is omitted. Applicable. In that case, the paper feed roller 12 also serves as the intermediate transport roller 15 and transports the paper P until slack is formed at the leading edge of the paper P that has reached the registration roller 17.

  Furthermore, in the present embodiment, the printing apparatus 1 has been described as an ink jet printing apparatus. However, the present invention is not limited to this, and any sheet feeding apparatus that supplies sheets stacked on a sheet feeding table one by one can be used. The present invention can also be applied to a paper feeding device of an ink jet type printing apparatus such as a system, a stencil printing system, and a thermal transfer system.

  In the present embodiment, the paper feeding device integrally incorporated in the printing apparatus has been described as an example. However, the present invention can also be applied to a paper feeding device independent of the printing apparatus.

  As described above, the present invention is not limited to the above-described embodiments, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment.

  And according to embodiment described above, invention of each aspect shown below is disclosed.

First, as an invention according to the first aspect,
Based on the timing at which the detection unit detects the paper before the skew correction unit that corrects the skew of the paper fed by the paper feed unit and sends it to the image forming unit, the detection unit and the skew correction unit In the paper feeding device that decelerates the paper conveyance speed by the paper feeding unit at a predetermined position between them to a constant speed lower than that before detection of the paper by the detection unit,
Based on the length of time from the start of paper feed by the paper feed unit to the detection of paper by the detection unit, the start of a deceleration section that decelerates the paper transport speed at the end of arrival of the paper at the predetermined location A deceleration pattern determination unit that determines a deceleration pattern including a time point;
A deceleration control unit that decelerates the sheet conveyance speed by the sheet feeding unit to the constant conveyance speed by the deceleration pattern determined by the deceleration pattern determination unit;
An invention of a paper feeding device comprising the above is disclosed.

  According to the sheet feeding device of the invention according to the first aspect, the sheet is located at a predetermined position between the detection unit and the skew correction unit according to the timing when the detection unit detects the sheet before the skew correction unit. A deceleration pattern including a start point of a deceleration section in which the sheet conveyance speed is decelerated to a constant conveyance speed is determined, with the point of time reaching the end point being the end point.

  For this reason, for example, the sheet conveyance speed detected by the detection unit at an early timing when the sheet conveyance amount by the sheet feeding unit is large is longer than the sheet detected by the detection unit at a later timing in the deceleration section. It can be decelerated. Accordingly, it is possible to further reduce the conveyance speed until the decelerated paper reaches the skew feeding correction portion, and to further reduce the impact sound when the paper reaches the skew feeding correction portion.

  In addition, for example, a paper conveyance speed deceleration period detected at a low timing by the detection unit with a small paper conveyance amount at the initial stage of paper delivery by the paper feeding unit is started at a later time than the paper detected at an early timing, and It is possible to lengthen the period during which the sheet is conveyed at a high speed. As a result, even if the paper conveyance speed is reduced to a constant speed in the deceleration zone before reaching the skew correction unit in order to reduce the impact sound when the paper reaches the skew correction unit, the skew correction unit The sheet can reach the skew correction unit at a pace sufficient to correct the skew of the sheet.

Next, as an invention according to the second aspect,
The deceleration pattern determination unit determines the deceleration pattern including a start point and an end point of a constant speed section for transporting paper at a constant transport speed following the deceleration section, and the constant speed transport speed. An apparatus invention is disclosed.

  According to the sheet feeding device of the invention according to the second aspect, the constant speed section in which the sheet is conveyed at a constant speed following the deceleration section according to the timing at which the detection unit detects the sheet before the skew feeding correction section. A deceleration pattern including the start time and end time of the above and a constant conveyance speed is determined.

  For this reason, even if the sheet conveyance speed (constant speed conveyance speed) in the subsequent constant speed section differs due to the difference in the start point of the deceleration section, the skew feeding correction section before the sheet feeding to the image forming section is started. The conveyance of the sheet by the sheet feeding unit is stopped at the same timing, and the conveyance of the sheet in the constant speed section can be executed at a conveyance speed and period in which the amount of slack formed on the sheet is constant.

Subsequently, as an invention according to the third aspect,
An invention of a paper feeding device is disclosed in which the deceleration pattern determination unit determines the deceleration pattern on the premise that the sheet conveyance speed is decelerated at a predetermined acceleration in the deceleration section.

  According to the sheet feeding device of the invention according to the third aspect, the sheet conveyance speed is decelerated at a predetermined acceleration in the deceleration zone. Therefore, by determining the start point of the deceleration section according to the timing when the detection unit detects the paper, the paper conveyance amount before deceleration is adjusted according to the initial paper conveyance amount by the paper supply unit. can do.

Next, as an invention according to the fourth aspect,
Based on the deceleration pattern determined by the deceleration pattern determination unit, the conveyance speed of the sheet by the sheet feeding unit that is stopped before the skew feeding correction unit sends the arrived sheet to the image forming unit is set to the constant speed. A stop pattern determining unit that determines a stop pattern including a start point of a stop section that is decelerated from the transport speed to zero, and the transport speed of the sheet is set to the constant transport speed by the stop pattern determined by the stop pattern determining unit. An invention of a sheet feeding device further comprising a stop control unit that decelerates from the above is disclosed.

  According to the sheet feeding device of the invention according to the fourth aspect, the length of the stop section in which the conveyance of the sheet that reaches the skew feeding correction section at a constant speed after deceleration is stopped from the constant speed before the rotation of the registration roller is started. Is determined based on the deceleration pattern determined by the deceleration pattern determination unit. For this reason, the length of the stop section is set to a length suitable for stopping the conveyance of the sheet according to whether the conveyance speed (constant speed) of the sheet when reaching the skew feeding correction unit is fast or slow. be able to.

Furthermore, as an invention according to the fifth aspect,
An invention of a sheet feeding device that determines the stop pattern on the premise that the stop pattern determination unit decelerates the sheet conveyance speed at a predetermined acceleration in the stop section is disclosed.

  According to the sheet feeding device of the invention according to the fifth aspect, the sheet conveyance speed is decelerated at a predetermined acceleration in the stop section. For this reason, by determining the start time of the stop section according to the deceleration pattern determined by the deceleration pattern determination unit, the sheet conveyance according to the sheet conveyance speed (constant speed) when reaching the skew correction unit The amount of speed reduction can be adjusted to the amount necessary for stopping.

DESCRIPTION OF SYMBOLS 1 Printing apparatus 2 Paper conveyance part 3 Printing part 4 Control part 5 Paper feed part 6 Skew correction part 7 Detection part 11 Paper feed stand 12 Paper feed roller 12a Scraper roller 12b Pickup roller 12c Scrape board 14 Paper feed motor 15 Intermediate conveyance roller 16 Intermediate Conveyance Motor 17 Registration Roller 18 Registration Motor 19 Registration Sensor (Detection Unit)
21 Belt conveying section 22 Inkjet head section C Constant speed transition location (predetermined location)
D Detection location P Paper R Transport path T1 Time from paper detection to end of V1 (high speed) section T2 Time from V2 (low speed) section Ta Time from paper feeding to detection Tc Primary paper feed to registration rollers Time required for V1 Predetermined speed V2 Low speed

Claims (5)

Based on the timing at which the detection unit detects the paper before the skew correction unit that corrects the skew of the paper fed by the paper feed unit and sends it to the image forming unit, the detection unit and the skew correction unit In the paper feeding device that decelerates the paper conveyance speed by the paper feeding unit at a predetermined position between them to a constant speed lower than that before detection of the paper by the detection unit,
Based on the length of time from the start of paper feed by the paper feed unit to the detection of paper by the detection unit, the start of a deceleration section that decelerates the paper transport speed at the end of arrival of the paper at the predetermined location A deceleration pattern determination unit that determines a deceleration pattern including a time point;
A deceleration control unit that decelerates the sheet conveyance speed by the sheet feeding unit to the constant conveyance speed by the deceleration pattern determined by the deceleration pattern determination unit;
A paper feeding device comprising:   The deceleration pattern determination unit determines the deceleration pattern including a start time and an end time of a constant speed section that conveys a sheet at a constant transport speed following the deceleration section, and the constant speed transport speed. 1.   3. The sheet feeding device according to claim 1, wherein the deceleration pattern determination unit determines the deceleration pattern on the assumption that a sheet conveyance speed is decelerated at a predetermined acceleration in the deceleration section.   Based on the deceleration pattern determined by the deceleration pattern determination unit, the conveyance speed of the sheet by the sheet feeding unit that is stopped before the skew feeding correction unit sends the arrived sheet to the image forming unit is set to the constant speed. A stop pattern determining unit that determines a stop pattern including a start point of a stop section that is decelerated from the transport speed to zero, and the transport speed of the sheet is set to the constant transport speed by the stop pattern determined by the stop pattern determining unit. The sheet feeding device according to claim 1, further comprising: a stop control unit that decelerates from the start.   5. The sheet feeding device according to claim 4, wherein the stop pattern determination unit determines the stop pattern on the assumption that a sheet conveyance speed is decelerated at a predetermined acceleration in the stop section.

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