JP2017007245A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer capable of reducing spoilage.SOLUTION: A printer 1 comprises: a feeding part 2 which feeds a sheet being a continuous sheet from a sheet roll; a head-lower-side conveyance part 4 which conveys the sheet fed by the feeding part 2 along a conveyance path on the lower side of an ink jet head; an upstream side buffer part 3 which stores a slack portion of the sheet between the feeding part 2 and the head-lower-side conveyance part 4; and a control part 8 which controls the feeding part 2 and the head-lower-side conveyance part 4. The control part 8 starts the head-lower-side conveyance part 4 after starting the feeding part 2 at the time of sheet conveyance start, drives the head-lower-side conveyance part 4 at an acceleration speed higher than an acceleration speed of the feeding part 2, and accelerates the feeding part 2 and the head-lower-side conveyance part 4 up to a printing conveyance speed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a printing apparatus for printing on continuous paper.

  2. Description of the Related Art There is known a printing apparatus that prints a sheet that is a continuous sheet from a sheet roll and ejects ink from an inkjet head onto the sheet while transporting the sheet.

  In such a printing apparatus, when printing is performed, the paper roll is rotated to start feeding the paper, and then printing is performed after the paper transport speed reaches a predetermined speed. The portion of the paper that has been transported under the inkjet head from the start of transport until the predetermined speed is reached is not used for printing and is wasted. This wasted part is called waste paper.

  By the way, the paper roll has a large moment of inertia. For this reason, a certain amount of time is required from the start of rotation of the paper roll until the paper conveyance speed reaches a predetermined speed and printing becomes possible. As a result, the amount of waste paper increases.

  On the other hand, Patent Document 1 discloses an image recording apparatus that prints a test pattern for recording inspection on a portion that becomes damaged during conveyance of a sheet. As a result, the technique disclosed in Patent Document 1 reduces paper waste.

JP 2011-98547 A

  However, in the technique of Patent Document 1, the portion of the paper that becomes damaged paper is only used for a purpose other than printing of the image of the printed matter, and the actual amount of lost paper is not reduced. Absent.

  The present invention has been made in view of the above, and an object of the present invention is to provide a printing apparatus that can reduce waste paper.

  In order to achieve the above object, a first feature of a printing apparatus according to the present invention is that a feeding unit that feeds a sheet of continuous paper from a sheet roll, and a conveyance path below the inkjet head that feeds the sheet fed by the feeding unit. A head lower transport section that transports the paper along the head, a paper storage section that stores a slack portion of the paper between the delivery section and the head lower transport section, and a control section that controls the feed section and the head lower transport section. The control unit, at the time of starting paper conveyance, activates the transport unit below the head after activating the feed unit, and drives the transport unit below the head at an acceleration greater than the acceleration of the feed unit, The delivery part and the head lower transport part are accelerated to a printing transport speed.

  A second feature of the printing apparatus according to the present invention is that the control unit is configured such that a conveyance distance by the sending unit up to a time when both the sending unit and the lower head conveying unit reach a printing conveyance speed, The start timing of the transport unit below the head is controlled so as to be equal to the sum of the transport distance by the transport unit and the specified sag amount equal to or less than the maximum sag amount that can be stored in the sheet storage unit.

  A third feature of the printing apparatus according to the present invention is that the control unit controls the start timing of the lower head transport unit so that the lower head transport unit reaches the print transport speed earlier than the sending unit. There is.

  According to the first feature of the printing apparatus according to the present invention, at the time of starting the paper conveyance, the control unit activates the under-head conveyance unit after activating the sending-out unit, and causes the under-head conveyance unit to be activated by the acceleration of the sending-out unit. Driven with a large acceleration, the sending section and the head lower transport section are accelerated to the print transport speed. As a result, the feeding section and the head lower transport section are activated at the same time, and the head lower transport section is accelerated until the print transport speed is reached at the same speed as the feeding section. The conveyance distance by the part can be reduced. As a result, waste paper can be reduced.

  According to the second feature of the printing apparatus according to the present invention, the control unit determines that the transport distance by the sending unit up to the time when both the sending unit and the head lower transport unit reach the print transport speed is determined by the head lower transport unit. The start timing of the transport unit under the head is controlled so as to be equal to the sum of the transport distance and the specified amount of sag that is equal to or less than the maximum amount of sag that can be stored in the paper storage unit. Accordingly, it is possible to prevent the sheet from becoming excessively slack and to allow the sheet to have a specified amount of sag.

  According to the third feature of the printing apparatus of the present invention, the control unit controls the start timing of the lower head transport unit so that the lower head transport unit reaches the print transport speed earlier than the sending unit. As a result, it is possible to shorten the time from the start of paper conveyance to the start of printing compared to the case where the feeding unit and the lower head conveyance unit are activated at the same time and the lower head conveyance unit is accelerated to the printing conveyance speed at the same acceleration as the sending unit. .

1 is a schematic configuration diagram of a printing apparatus according to an embodiment. FIG. 3 is a control block diagram of the printing apparatus according to the embodiment. 6 is a flowchart for explaining the operation of the printing apparatus according to the embodiment. It is explanatory drawing of the conveyance state of the paper in the printing apparatus which concerns on embodiment. It is explanatory drawing of the conveyance state of the paper in the printing apparatus which concerns on embodiment. FIG. 10 is a diagram illustrating a transition of a conveyance speed by a sending unit and a conveyance speed by a head lower conveyance unit from a paper conveyance start point in the printing apparatus according to the embodiment. FIG. 6 is a diagram illustrating a transition of a conveyance distance by a sending unit and a conveyance distance by a head lower conveyance unit from a paper conveyance start point in the printing apparatus according to the embodiment. It is a figure which shows transition of the conveyance speed from the paper conveyance start time in a comparative example. It is a figure which shows transition of the conveyance distance from the paper conveyance start time in a comparative example.

  Embodiments of the present invention will be described below with reference to the drawings. Throughout the drawings, the same or equivalent parts and components are denoted by the same or equivalent reference numerals.

  The following embodiments exemplify devices for embodying the technical idea of the present invention, and the technical idea of the present invention is the material, shape, structure, arrangement, etc. of each component. Is not specified as follows. The technical idea of the present invention can be variously modified within the scope of the claims.

  FIG. 1 is a schematic configuration diagram of a printing apparatus according to an embodiment of the present invention. FIG. 2 is a control block diagram of the printing apparatus shown in FIG. In the following description, the top, bottom, left, and right of the paper surface in FIG. Further, the direction orthogonal to the paper surface of FIG.

  As shown in FIGS. 1 and 2, the printing apparatus 1 according to the present embodiment includes a delivery unit 2, an upstream buffer unit (corresponding to a sheet storage unit in claims) 3, a head lower transport unit 4, A head unit 5, a downstream buffer unit 6, a winding unit 7, and a control unit 8 are provided.

  The delivery unit 2 sends out the paper P from the paper roll 10. The paper roll 10 is a roll of paper P, which is a long continuous paper. The delivery unit 2 includes a paper roll support shaft 11 and a delivery motor 12.

  The paper roll support shaft 11 rotatably supports the paper roll 10. The paper roll support shaft 11 is formed in a long shape extending in the front-rear direction.

  The feed motor 12 rotates the paper roll support shaft 11 clockwise in FIG. The rotation of the sheet roll support shaft 11 causes the sheet roll 10 to rotate in the same direction, and the sheet P is sent out to the downstream side (right side).

  The upstream buffer unit 3 accumulates a slack portion of the paper P between the feeding unit 2 and the head lower conveyance unit 4. The upstream buffer unit 3 includes support rollers 16 and 17 and a dancer roller 18.

  The support rollers 16 and 17 support the paper P between the delivery unit 2 and the head lower conveyance unit 4. The support rollers 16 and 17 are spaced apart from each other by a predetermined distance in the left-right direction and are disposed at the same height.

  The dancer roller 18 pushes down the paper P by its own weight between the support rollers 16 and 17. As a result, the slack portion of the paper P generated between the delivery unit 2 and the head lower conveyance unit 4 is absorbed by the upstream buffer unit 3. The dancer roller 18 moves up and down according to the amount of slack of the paper P.

  The head lower transport unit 4 transports the paper P sent out by the sending unit 2 along a transport path below ink jet heads 41A to 41D described later. The head lower transport unit 4 includes upstream guide rollers 21 to 23, a tension applying roller 24, a brake 25, head lower support rollers 26 to 30, a driving roller 31, a head lower transport motor 32, and a downstream guide. And rollers 33-35.

  The upstream guide rollers 21 to 23 guide the paper P between the upstream buffer unit 3 and the head lower support roller 26.

  The tension applying roller 24 is for applying tension to the paper P. The tension applying roller 24 nips the paper P with the upstream guide roller 21 and rotates with the transported paper P. By applying the brake to the tension applying roller 24 by the brake 25, tension is applied to the paper P between the tension applying roller 24 and the driving roller 31, and the slack of the paper P during this time is prevented.

  The brake 25 brakes the tension applying roller 24. The brake 25 is a powder brake, for example.

  The head lower support rollers 26 to 30 support the paper P immediately below the ink jet heads 41A to 41D. The conveyance path of the paper P below the inkjet heads 41A to 41D is formed by the head lower support rollers 26 to 30. The head lower support rollers 26 to 30 are arranged at the same height at intervals along the conveyance direction (left-right direction) of the paper P.

  The driving roller 31 conveys the paper P in the right direction by rotating while nipping the paper P with the lower support roller 30.

  The under-head transport motor 32 drives the drive roller 31 to rotate.

  The downstream guide rollers 33 to 35 guide the paper P between the head lower support roller 30 and the downstream buffer unit 6.

  The head unit 5 prints on the paper P conveyed on the lower support rollers 26 to 30. The head unit 5 has four inkjet heads 41A to 41D.

  The ink jet heads 41 </ b> A to 41 </ b> D discharge ink onto the paper P. The inkjet heads 41 </ b> A to 41 </ b> D each have a plurality of nozzles (not shown) arranged along the main scanning direction (front-rear direction) orthogonal to the sub-scanning direction (left-right direction) that is the transport direction of the paper P. Ink is ejected from the nozzles. The ink jet heads 41A to 41D eject inks of different colors (for example, black, cyan, magenta, and yellow).

  The downstream buffer unit 6 stores a slack portion of the paper P between the lower head transport unit 4 and the winding unit 7. The downstream buffer unit 6 includes support rollers 46 and 47 and a dancer roller 48.

  The support rollers 46 and 47 support the paper P between the lower head transport unit 4 and the winding unit 7. The support rollers 46 and 47 are arranged at the same height and spaced apart from each other by a predetermined distance in the left-right direction.

  The dancer roller 48 pushes down the paper P by its own weight between the support rollers 46 and 47. As a result, the slack portion of the paper P generated between the head lower conveyance unit 4 and the winding unit 7 is absorbed by the downstream buffer unit 6. The dancer roller 48 moves up and down according to the amount of slack of the paper P.

  The winding unit 7 winds the printed paper P. The winding unit 7 includes a winding shaft 51 and a winding motor 52.

  The take-up shaft 51 takes up and holds the paper P. The winding shaft 51 is formed in a long shape extending in the front-rear direction.

  The winding motor 52 rotates the winding shaft 51 in the clockwise direction in FIG. The sheet P is wound around the winding shaft 51 by the rotation of the winding shaft 51.

  The control unit 8 controls the operation of each unit of the printing apparatus 1. The control unit 8 includes a CPU, a RAM, a ROM, a hard disk, and the like.

  When printing, the control unit 8 drives the delivery unit 2, the head lower conveyance unit 4, and the take-up unit 7 to convey the paper P, and ejects ink from the inkjet heads 41 </ b> A to 41 </ b> D to the paper P. Let it print.

  The control unit 8 activates the under-head conveyance unit 4 after activating the delivery unit 2 at the time of starting conveyance of the paper when performing printing. Then, the control unit 8 drives the lower head transport unit 4 at an acceleration larger than the acceleration of the sending unit 2 to accelerate the sending unit 2 and the lower head transport unit 4 to the printing transport speed V.

  Next, the operation of the printing apparatus 1 will be described.

  When the operation of the printing apparatus 1 is started, a new paper roll 10 is installed in the delivery unit 2, and the leading end of the paper P of the paper roll 10 is connected to the take-up shaft 51.

  FIG. 3 is a flowchart for explaining the operation of the printing apparatus 1. The process of the flowchart of FIG. 3 starts when a print job is input to the printing apparatus 1.

  In step S <b> 1 of FIG. 3, the control unit 8 activates the delivery unit 2. Specifically, the control unit 8 causes the feed motor 12 to start the rotation of the paper roll 10. As a result, the paper P starts to be conveyed from the paper roll 10 toward the upstream buffer unit 3.

Control unit 8 controls so that delivery unit 2 accelerates the sheet P at a predetermined acceleration a _U. Acceleration a _U is set to feasible values in the moment of inertia of the paper roll 10 new. It should be noted that even after the printing is interrupted, the control unit 8 does not prevent the feeding unit 2 from starting even when the feeding unit 2 is restarted when the paper roll 10 is smaller than a new one and the paper roll 10 is resumed with a small moment of inertia. 2 is driven at an acceleration _{a U.}

  When the paper P is delivered from the paper roll 10 by the activation of the delivery unit 2, as shown in FIG. 4, the dancer roller 18 descends in the upstream buffer unit 3, and the slack portion of the paper P is absorbed by the upstream buffer unit 3. Is done.

  Returning to FIG. 3, following step S <b> 1, in step S <b> 2, the control unit 8 determines whether or not the preset activation timing of the lower head transport unit 4 has been reached. A method of determining the start timing of the head lower transport unit 4 will be described later. When it is determined that it is not the start timing of the lower head transport unit 4 (step S2: NO), the control unit 8 repeats step S2.

  When it is determined that the start timing of the lower head transport unit 4 has come (step S2: YES), in step S3, the control unit 8 starts the lower head transport unit 4 and the winding unit 7. Specifically, the control unit 8 starts rotation of the drive roller 31 by the under-head transport motor 32 and activates the brake 25. Further, the control unit 8 causes the winding motor 52 to start rotating the winding shaft 51. As a result, the paper P starts to be conveyed immediately below the ink jet heads 41 </ b> A to 41 </ b> D, and the paper P starts to be wound around the winding shaft 51.

Control unit 8 controls so that the head lower transporting unit 4 to accelerate the sheet P at a predetermined acceleration a _H. The acceleration a _H is set to the acceleration a _U value greater than the delivery unit 2. The control unit 8 controls the winding unit 7 to wind the paper P at the same acceleration as that of the lower head transport unit 4.

  By starting the under-head transport unit 4 and the winding unit 7, the sheet P is transported from the delivery unit 2 to the winding unit 7 as shown in FIG. 5. After activation of the lower head transport unit 4, the difference in transport speed between the sending unit 2 and the lower head transport unit 4 is reduced, and the amount of sag in the upstream buffer unit 3 is reduced.

  Returning to FIG. 3, following step S <b> 3, in step S <b> 4, the control unit 8 determines whether or not the under-head transport unit 4 has reached the print transport speed V. When it is determined that the head lower transport unit 4 has not reached the print transport speed V (step S4: NO), the control unit 8 repeats step S4.

  When it is determined that the head lower transport unit 4 has reached the print transport speed V (step S4: YES), in step S5, the control unit 8 controls the head unit 5 to start printing. Specifically, the control unit 8 controls the ink jet heads 41 </ b> A to 41 </ b> D based on the print job to eject ink onto the paper P.

  Here, after the head lower transport unit 4 reaches the print transport speed V, the control unit 8 controls the head lower transport unit 4 to maintain the print transport speed V. In the lower head transport unit 4, the tension is applied to the tension applying roller 24 by the brake 25, so that the paper P is transported at the print transport speed V while suppressing sagging.

  Further, when the head lower transport unit 4 reaches the print transport speed V, the control unit 8 controls the subsequent winding speed by the winding unit 7 to be equal to the print transport speed V. In addition, when the delivery unit 2 reaches the print conveyance speed V, the control unit 8 controls the delivery unit 2 to maintain the print conveyance speed V.

  Subsequent to step S5, in step S6, the control unit 8 determines whether printing based on the print job is finished. When it is determined that printing has not ended (step S6: NO), the control unit 8 repeats step S6.

  When it is determined that the printing is finished (step S7: YES), in step S7, the control unit 8 stops the sending unit 2, the head lower transport unit 4, and the winding unit 7. Thereby, the operation of the printing apparatus 1 is completed.

FIG. 6 shows the transition of the conveyance speed by the sending unit 2 and the conveyance speed by the head lower conveyance unit 4 from the start point of paper conveyance of the printing apparatus 1 that performs the above-described operation. Further, transition of the conveyance distance l _H by conveyance distance l _U and head lower transporting section 4 by the feeding unit 2 from the paper conveyance start of the printing apparatus 1 is as shown in FIG.

As shown in FIGS. 6 and 7, the head lower conveyance unit 4 is activated at a time t = t _S from the activation of the sending unit 2, and the head lower conveyance unit 4 is at a print conveyance speed at t = t _H. Let V be reached. The lower head transport unit 4 transports the portion of the paper P held in the upstream buffer unit 3 while accelerating at an acceleration a _H from t = t _S to t = t _H.

During this time, since the paper P has not reached the print conveyance speed V, printing is not started. In other words, the portion of the paper P that has been transported by the lower head transport section 4 until t = t _H becomes the waste paper. Waste paper weight l _P corresponds to the area of a region indicated by oblique lines in FIG. 6, represented by the following formula (1).

l _P = V ² / 2a _H (1)
On the other hand, as a comparative example, when the sending unit 2 and the head lower transport unit 4 are activated simultaneously and accelerated to the print transport speed V with the same acceleration a _U , the transport speed of the sending unit 2 and the head lower transport unit 4 is increased. The transition and the transition of the transport distance are shown in FIGS. 8 and 9, respectively.

In this comparative example, the portion transported by the under-head transport unit 4 from the start of the feeding unit 2 and the under-head transport unit 4 until the paper P reaches the print transport speed V becomes damaged paper. The paper loss amount l _{PC in} this case corresponds to the area of the hatched area in FIG. 8 and is expressed by the following equation (2).

l _PC = V ² / 2a _U (2)
As described above, since a _H > a _U , the paper loss amount l _P in the present embodiment is smaller than the paper loss amount l _PC in the comparative example.

  Next, a method for determining the activation timing of the head lower conveyance unit 4 will be described.

The start timing of the lower head transport section 4 is such that the lower head transport section 4 reaches the print transport speed V earlier than the delivery section 2, and both the feed section 2 and the lower head transport section 4 are at the print transport speed V. The transport distance l _U by the delivery unit 2 up to the point of time is determined to be equal to the sum of the transport distance l _H by the head lower transport unit 4 and the specified sag amount l _B.

That is, as shown in FIGS. 6 and 7, when time t = t _U from the start of the sending unit 2 when the sending unit 2 reaches the printing conveyance speed V, at t = t _U , the following formula ( The time t _S from the start-up of the sending-out unit 2 to the start-up of the lower head transport unit 4 is determined so that 3) holds.

l _U = l _H + l _B (3)
The prescribed sag amount l _B is set as the sag amount held by the upstream buffer unit 3 during printing. Defined sag length l _B is set as a value capable of absorbing the difference in the conveying speed of the feeding section 2 and the head lower conveyor 4 at the upstream side buffer unit 3. The prescribed sag amount l _B is set to a value equal to or less than the maximum sag amount that can be accumulated in the upstream buffer unit 3. The maximum amount of sag is determined by the configuration of the upstream buffer unit 3. Specifically, the maximum amount of sag in the upstream buffer unit 3 is determined by the distance from the support rollers 16 and 17 to the bottom plate (not shown) of the casing of the printing apparatus 1.

The transport distance l _U by the delivery unit 2 and the transport distance l _H by the head lower transport unit 4 at t = t _U are expressed by the following equations (4) and (5), respectively.

l _U = V / 2t _U (4)
l _H = (t _H −t _S ) V / 2 + (t _U −t _H ) V (5)
t _H and t _U are expressed by the following equations (6) and (7), respectively.

t _H = t _S + V / a _H (6)
t _U = V / a _U (7)
From the equations (3) to (7), the following equation (8) is obtained.

t _S = (1 / a _U −1 / a _H ) V / 2 + l _B / V (8)
The timing after the time t _S represented by the equation (8) from the activation of the delivery unit 2 is the activation timing of the head lower conveyance unit 4.

  As described above, in the printing apparatus 1, the control unit 8 activates the under-head conveyance unit 4 after activating the delivery unit 2 at the start of sheet conveyance when performing printing. Then, the control unit 8 drives the lower head transport unit 4 at an acceleration larger than the acceleration of the sending unit 2 to accelerate the sending unit 2 and the lower head transport unit 4 to the printing transport speed V. As a result, the sheet feeding P 2 and the head lower conveyance unit 4 are simultaneously activated, and the paper P is printed at a printing conveyance speed V as compared with the case where the head lower conveyance unit 4 is accelerated to the print conveyance speed V at the same acceleration as the delivery unit 2. It is possible to reduce the transport distance by the head lower transport unit 4 until it reaches. As a result, waste paper can be reduced.

Further, the control unit 8 determines that the transport distance l _U by the sending unit 2 up to the time when both the sending unit 2 and the head lower transport unit 4 reach the print transport speed V is the transport distance l _H by the head lower transport unit 4. The start timing of the under-head transport unit 4 is controlled so as to be equal to the sum of the prescribed sag amount 1 _B which is equal to or less than the maximum sag amount in the upstream buffer unit 3. Accordingly, slack of the paper P on the upstream side buffer unit 3 after the time when both the delivery part 2 and the head lower transporting section 4 becomes the printing conveyance speed V is defined sag length l _B. As a result, while suppressing that the slack of the paper P is excessive, it is possible to slack the prescribed slack amount l _B on the sheet P.

  Further, the control unit 8 controls the start timing of the lower head transport unit 4 so that the lower head transport unit 4 reaches the print transport speed V earlier than the sending unit 2. As a result, the feeding unit 2 and the head lower transport unit 4 are activated at the same time, and the head lower transport unit 4 is accelerated from the sheet transport start to the printing start as compared with the case where the head lower transport unit 4 is accelerated to the print transport speed V at the same acceleration as the feed unit 2 Can be shortened.

  Note that the lower head transport unit 4 may reach the print transport speed V later than the delivery unit 2. Even in this case, waste paper can be reduced.

  In the above-described embodiment, the upstream buffer unit 3 is configured by a pair of support rollers 16 and 17 and the dancer roller 18, but the configuration of the upstream buffer unit is not limited thereto. For example, the structure which provided multiple combinations of the support roller and the dancer roller may be sufficient.

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

DESCRIPTION OF SYMBOLS 1 Printing apparatus 2 Sending part 3 Upstream buffer part 4 Head lower conveyance part 5 Head unit 6 Downstream buffer part 7 Winding part 8 Control part 10 Paper roll 11 Paper roll support shaft 12 Sending motor 16, 17, 46, 47 Support Roller 18, 48 Dancer roller 21-23 Upstream guide roller 24 Tension applying roller 25 Brake 26-30 Head lower support roller 31 Drive roller 32 Head lower transport motor 33-35 Downstream guide roller 41A-41D Inkjet head 51 Winding shaft 52 Winding motor

Claims (3)

A feeding section for feeding the continuous paper from the paper roll;
A head lower transport unit that transports the paper fed by the feed unit along a transport path below the inkjet head;
A paper storage section for storing a slack portion of the paper between the delivery section and the lower head transport section;
A control unit for controlling the delivery unit and the head lower conveyance unit,
The control unit activates the under-head conveyance unit after activating the sending-out unit at the start of paper conveyance, and drives the under-head conveyance unit at an acceleration larger than the acceleration of the sending-out unit. And a printing apparatus characterized by accelerating the lower head transport section to a print transport speed.   In the control unit, the conveyance distance by the sending unit until the time when both the sending unit and the lower head conveyance unit reach the printing conveyance speed is accumulated in the conveyance distance by the lower head conveyance unit and the sheet storage unit. 2. The printing apparatus according to claim 1, wherein the start timing of the under-head transport unit is controlled so as to be equal to a sum of a predetermined amount of sag that is equal to or less than a maximum amount of sag. 3. The control unit according to claim 1, wherein the control unit controls the start timing of the lower head transport unit so that the lower head transport unit reaches the print transport speed earlier than the sending unit. 4. Printing device.