JP2011161788A - Printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a printing area on paper sheets by a second printing tool from fluctuating, in a printer configured such that paper sheets after printed by a first printing tool are once stored in a storing section and then transported to the second printing tool by a paper re-feeding device. <P>SOLUTION: The printer includes: a first printing tool 3 for printing on one side of paper sheets P; a paper storing section 4 for temporarily storing the printed paper sheets P; a second printing tool 5 for printing on one side or the other side of the paper sheets P; and a paper re-feeding device 8B for transporting the paper sheets P printed on one side from the paper storing sections 4 to the second printing tool 5. In this printer, a relative position in the transporting direction of the paper sheets P for the plate surface 51a of the second printing tool 5 is adjusted by a printing position adjuster 83. Then, the relative position is adjusted corresponding to whether the printing process performed by the second printing tool 5 is a parallel printing process performed with the first printing tool 3 or a single printing process. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a printing apparatus, and more particularly to a printing apparatus configured to print once on printing paper and then print again on the printing paper, such as a duplex printing apparatus.

  In recent years, it has been desired to reduce the amount of paper used for printing from the viewpoint of environmental problems, and for this reason, double-sided printing, in which printing is performed on the front and back surfaces of paper, has been actively performed. As a double-sided printing apparatus for performing double-sided printing, for example, a double-sided stencil printing apparatus for performing stencil printing has been proposed. As an example of this apparatus, a cylindrical first drum in which perforated stencil paper is wound around an outer peripheral surface. And the second drum are arranged adjacent to each other, the first drum performs printing on the front surface of the paper, the paper on which the front surface is printed is conveyed to the second drum, and the second drum performs printing on the back surface of the paper. The device is known. In such a duplex printing apparatus, printing is performed while a sheet is pressed against a stencil sheet serving as a printing plate by a press roller or the like, and the sheet is conveyed by rotation of a drum.

  As described above, in a printing apparatus that performs printing while transporting a sheet by a rotating drum or the like, the sheet is always at a predetermined relative position (relative position in the transport direction) with respect to the plate surface of the moving stencil sheet or the like. It is necessary to set the paper transport timing. If this is not the case, there arises a problem that the printing area on the paper fluctuates in the vertical direction. In Patent Document 1, a sheet sensor is disposed between a drum and a sheet conveying roller disposed upstream of the sheet conveying direction, and the acceleration of the conveying roller is determined based on the timing at which the sensor detects the sheet. A printing apparatus that prevents the occurrence of the above problem by controlling is shown.

  In the double-sided printing apparatus as described above, in order to dry the paper printed by the first drum, a paper storage unit that temporarily stores them is often provided. In that case, a paper re-feeding unit that transports the paper temporarily stored in the paper storage unit to the second drum is provided. In many cases, this type of re-feeding means is configured to include a conveyance roller including a pair of nip rollers that sandwich a sheet. It is shown.

JP 2006-103171 A JP 2009-012216 A

  By the way, in the conventional printing apparatus having the two printing units as described above and having the sheet storage portion disposed between them, when printing on a large number of sheets, the printing unit on the rear side is used. It was found that the printing area on the paper is likely to fluctuate in the vertical direction, that is, in the paper transport direction.

  The above problem is not limited to the duplex printing apparatus, but other sheets such as a multi-color printing apparatus are temporarily stored in the sheet storage unit after being printed by one printing means, and then another printing is performed by the refeeding means. It can occur in the same way in a printing device configured to transport to a means.

  The present invention has been made in view of the above circumstances, and in a printing apparatus including two printing units and a sheet storage unit disposed between them, a printing area on a sheet by a printing unit on the subsequent stage side. The purpose is to prevent the problem of fluctuation in the vertical direction.

The printing apparatus according to the present invention includes:
A first printing means for printing on one surface of the paper while conveying the paper while pressing the paper against a plate surface arranged on the drum circumferential surface, etc .;
A paper storage unit for temporarily storing the printed paper; and
A second printing means for printing on one surface or the other surface of the paper while the paper is pressed against the printing plate and conveyed;
A paper refeeding means for transporting the paper printed on the one surface from the paper storage section to a second printing means;
A printing apparatus comprising a common drive source for driving the respective sheet conveying sections of the first and second printing means;
A printing position adjusting means for adjusting a relative position of the paper in the conveyance direction with respect to the printing plate in the second printing means;
When the printing process performed by the second printing unit is a parallel printing process performed in parallel with the printing by the first printing unit, the appropriate adjustment amount of the relative position, and the printing process performed by the second printing unit Storage means for storing the appropriate adjustment amount of the relative position in association with each printing process, in the case of the single printing process only by the second printing means,
It is determined whether the printing performed on each sheet in the second printing means is the parallel printing process or the single printing process, and the appropriate adjustment amount associated with the determined printing process is stored in the memory. And a control means for setting the read appropriate adjustment amount in the printing position adjusting means.

  Here, the above-mentioned “common drive source” includes not only the case where the whole is common, such as a common motor, but also the case where at least a part is common. In other words, separate motors are used for the first printing means and the second printing means, but a common drive source is also used when a common power supply unit is used for them. It shall be.

In the printing apparatus of the present invention having the above configuration,
A paper counting means for counting the order of the paper transported by the re-feeding means from the state where the paper storage section is empty;
A print number setting means for setting a series of print numbers by the first and second printing means,
It is desirable that the control unit is configured to make the determination based on a design storage number of the paper storage unit, an order counted by the paper counting unit, and a print number set by the print number setting unit. .

In the printing apparatus of the present invention,
The proper adjustment amount stored in the storage means is individually determined for each paper transport speed of the first and second printing means,
The control unit is configured to receive information indicating the sheet conveyance speed of the first and second printing units and to read an appropriate adjustment amount stored for the sheet conveyance speed indicated by the information from the storage unit. It is desirable.

Furthermore, in the printing apparatus of the present invention,
Conveyance in which the printing position adjusting means is disposed at a position where the paper is fed to the second printing means constituting the refeed means, and the drive start timing and / or the average conveyance speed within a predetermined period are variable. Means,
It is desirable that the control means changes the drive start timing of the transport means and / or the average transport speed within a predetermined period.

  According to the research of the present inventor, as described above, in the printing apparatus including the two printing units and the sheet storage unit disposed therebetween, the printing area on the sheet by the printing unit on the rear stage side is It has been found that the problem of fluctuating in the vertical direction is likely to occur when a common driving source is used as the driving source for driving the paper conveying units of the two printing units. Hereinafter, this point will be described in detail.

  In a printing apparatus comprising the first and second printing means and a paper storage section disposed between them, the situation where printing is performed only by the second printing means on the rear stage side, and both printing Two situations can occur where the means print in parallel. That is, for example, in a printing apparatus in which the paper storage unit is designed to store 12 sheets, when printing is performed on a total of 20 sheets by designating the number of prints in advance, 12 is counted from the end of the printing order. When printing is performed on the first sheet (that is, the ninth sheet from the beginning) by the second printing unit, since printing on all the sheets is already completed in the first printing unit, Printing is performed only by the second printing means. The same applies to the case where the second printing unit prints on the paper whose printing order is later than the above paper (10th to 20th sheets from the beginning). On the other hand, when the second printing means prints on the first to eighth sheets counted from the beginning of the printing order, printing is also performed by the first printing means in parallel therewith. Here, in these two cases, the former is referred to as “single print processing” and the latter is referred to as “parallel printing processing”.

  On the other hand, in a printing unit that prints on a sheet while pressing the sheet placed on the drum circumferential surface and transporting the sheet, a driving source for driving a sheet transporting unit such as a drum is used for the pressing during printing. While a large load is applied, when the printing is not performed, the pressure is released so that the load on the driving source is reduced. Therefore, when a common drive source is used for the first and second printing units, the load on the drive source is smaller in the single print process than in the parallel print process. Normally, there is a backlash between a paper transport unit such as a drum and its drive mechanism, but when the motor load is reduced as described above, the backlash of the second printing means changes. Then, the angle of the paper transport unit such as a drum is shifted in the vertical direction, and the printing area on the paper is changed in the vertical direction.

The printing apparatus according to the present invention is obtained based on the above-mentioned new knowledge,
Printing position adjusting means for adjusting the relative position of the paper in the conveyance direction with respect to the printing plate in the second printing means;
When the printing process performed by the second printing unit is a parallel printing process performed in parallel with the printing by the first printing unit, the appropriate adjustment amount of the relative position, and the printing process performed by the second printing unit Storage means for storing the appropriate adjustment amount of the relative position in association with each printing process, in the case of the single printing process only by the second printing means,
It is determined whether the printing performed on each sheet in the second printing means is the parallel printing process or the single printing process, and the appropriate adjustment amount associated with the determined printing process is stored in the memory. And a control means for setting the read appropriate adjustment amount in the print position adjusting means.
In the case of the single printing process and the parallel printing process, the relative position of the sheet with respect to the printing plate is appropriately adjusted to prevent the problem that the print area on the sheet fluctuates in the vertical direction.

1 is a side view showing a schematic configuration of a printing apparatus according to an embodiment of the present invention. The partially broken side view which shows the principal part of the said printing apparatus Schematic explaining the paper and print area The block diagram which shows the structure in connection with the printing position control of the said printing apparatus. Time chart showing a change state of the paper conveyance speed in the printing apparatus Schematic explaining changes in print area on paper FIG. 5 is a time chart showing another example of a change state of the paper conveyance speed in the printing apparatus of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a double-sided stencil printing apparatus 1 according to an embodiment of the present invention, and FIG. 2 is a side view showing an enlarged main part thereof. As shown in FIG. 1, the double-sided stencil printing apparatus 1 is provided on an apparatus housing 10 and one side surface of the apparatus housing 10, that is, the left side surface in the figure, and stacks a plurality of sheets P as printing media. A paper feed tray 2 to be held, a first stencil printing unit (first printing means) 3 for printing on one surface of paper P fed from the paper feed tray 2, and a paper printed on one surface A paper storage section (hereinafter simply referred to as a storage section) 4 that temporarily stores a plurality of sheets of P, and a second stencil printing section (second storage) that prints on the other surface of the paper P stored in the storage section 4 Printing means) 5 and a paper discharge tray 6 provided on the other side surface of the apparatus housing 10, that is, the right side surface in the drawing, for stacking and holding the sheets P printed on both sides, that is, one surface and the other surface. Yes.

  Further, the double-sided stencil printing apparatus 1 includes a paper feeding unit 7 that feeds the paper P from the paper feeding table 2 to the first stencil printing unit 3, and a paper P that is fed from the first stencil printing unit 3 into the storage unit 4. A first intermediate transport unit 8A that transports the sheet P, a second intermediate transport unit 8B that transports the paper P from the inside of the storage unit 4 to the second stencil printing unit 5, and a discharge tray 6 from the second stencil printing unit 5 And a paper discharge unit 9 for conveying the paper P to the top.

  The paper feed unit 7 has a pickup roller 71 disposed so as to be positioned above the paper P stacked on the paper feed tray 2, and the paper P picked up by the pickup roller 71 at a first timing at a first timing. A timing roller 72 that feeds the stencil printing unit 3 is schematically configured. The timing roller 72 includes a pair of nip rollers. When the timing roller 72 is stopped, the paper feeding to the first stencil printing unit 3 is stopped.

  The first intermediate transport unit 8A reverses the sheet P printed on one surface (the upper surface in FIGS. 1 and 2) by the first stencil printing unit 3 along an arcuate trajectory. Is generally configured by a reversing device 73 that turns the paper P downward and a carry-in device 74 that carries the paper P reversed by the reversing device 73 into the storage unit 4. The first intermediate transport unit 8A constitutes a sheet reversing unit together with a second intermediate transport unit 8B and a storage unit 4 described later.

  The second intermediate transport unit 8B as a paper refeeding unit includes a carry-out device 81 that carries out the paper P stored in the storage unit 4, and a pickup roller 82 that picks up the paper P carried out by the carry-out device 81. And a timing roller 83 that sequentially conveys the paper P picked up by the pickup roller 82 to the second stencil printing unit 5 at a predetermined timing. The timing roller 83 includes a pair of nip rollers driven by the motor M1, and the pickup roller 82 basically has the same configuration.

  A first sensor S1 that detects the leading edge of the sheet P to be conveyed is disposed slightly downstream of the pickup roller 82 in the sheet conveyance direction, and is similarly conveyed in the sheet conveyance direction slightly downstream of the timing roller 83. A second sensor S2 that detects the leading edge of the paper P is provided.

  On the other hand, the paper discharge unit 9 is composed of a discharge device 84 that carries out the paper P, on which the other surface has been printed by the second stencil printing unit 5 and the double-sided printing has been completed, toward the paper discharge table 6.

  The carry-in device 74, the carry-out device 81, and the discharge device 84 are spanned around a pair of pulleys 74a, 81a, and 84a arranged at predetermined intervals, and the outer periphery of the pair of pulleys 74a, 81a, and 84a. Are provided with annular conveying belts 74b, 81b, and 84b that move as the pulleys 74a, 81a, and 84a rotate, and suction fans 74c, 81c, and 84c, respectively. The transport belts 74b, 81b, and 84b are formed with a number of holes that are not shown.

  In the carry-out device 81, the fan 81c sucks air in a case (not shown) that accommodates the transport belt 81b, and then sucks air from the hole of the transport belt 81b. A suction force is generated on the transfer surface. The carry-out device 81 sucks and holds only one sheet P in the storage unit 4 on the transport belt 81b by this suction force, and transfers the sheet P to the pickup roller 82 by the rotation of the transport belt 81b. The other carry-in device 74 and the discharge device 84 are basically configured similarly to the carry-out device 81.

  The devices 74, 81, and 84 configured as described above rotate the pulleys 74a, 81a, and 84a by a motor (not shown) to move the conveyor belts 74b, 81b, and 84b, and rotate the fans 74c, 81c, and 84c. By generating the aforementioned suction force, the paper P is conveyed while being sucked and held.

  The carry-in device 74 may be provided with a plurality of conveyance belts 74b and fans 74c that are stretched around the outer periphery of the pair of pulleys 74a in parallel so that a single sheet P can be sucked and held and conveyed. . The same applies to the carry-out device 81 and the discharge device 84.

  As shown in FIG. 2, the reversing device 73 has four pulleys 73a arranged along an arcuate locus, and is wound around the outer circumferences of the four pulleys 73a and moves as the pulleys 73a rotate. An annular conveyor belt 73b and a suction fan 73c are provided and operate in substantially the same manner as the devices 74, 81, 84.

  On the other hand, the first stencil printing unit 3 includes a first drum 31 and a first press roller 32. As shown in FIG. 2, a stripping claw 33 for stripping the paper P from the first drum 31 is provided on the downstream side of the first drum 31 in the paper transport direction. The first drum 31 has an ink cartridge (not shown) inside, and a stencil sheet 31 a is wound around the outer peripheral surface of the first drum 31. This stencil sheet 31a is made by thermal perforation based on input image data in a plate making unit (not shown). Then, the sheet P is fed between the first drum 31 and the press roller 32 by the timing roller 72 that is driven synchronously with the rotation of the first drum 31, and one surface thereof is pressed against the stencil sheet 31a by the press roller 32. Thus, stencil printing is performed on the one surface.

  Similar to the first stencil printing unit 3, the second stencil printing unit 5 includes a second drum 51 and a second press roller 52. The second drum 51 is rotationally driven together with the first drum 31 by a motor M2, which is a common drive source. In the vicinity of the second drum 51, a second drum reference sensor S3 for detecting the absolute rotational position is disposed. As this 2nd drum reference | standard sensor S3, what detects the detection piece attached to the side surface of the 2nd drum 51 photoelectrically etc. are applicable, for example. Further, on the downstream side of the second drum 51 in the paper conveyance direction, a peeling claw 53 for peeling the paper P from the second drum 51 is provided. The second drum 51 has an ink cartridge (not shown) inside, and a stencil sheet 51 a is wound around the outer peripheral surface of the second drum 51. This stencil sheet 51a is also made by thermal perforation based on image data in the same manner as the stencil sheet 31a. The sheet P is fed between the second drum 51 and the second press roller 52 by the timing roller 83 driven synchronously with the rotation of the second drum 51, and the other surface is pressed against the stencil sheet 51a by the press roller 52. Thus, stencil printing is performed on the other surface.

  The storage unit 4 temporarily stores a plurality of sheets of paper P printed on one surface by the first stencil printing unit 3 before sending it to the second stencil printing unit 5. The paper P is held in a box-shaped case 40 in a state where the paper P is stacked.

  Next, the operation of the double-sided stencil printing apparatus 1 of the present embodiment configured as described above will be described. Each operation is performed based on an instruction from a general control device (not shown) provided in the device housing 10.

  When performing double-sided stencil printing, first, the pickup roller 71 sequentially picks up the paper P stacked on the paper feed tray 2 at a predetermined time interval and sends it to the timing roller 72. The timing roller 72 conveys the paper P to the first stencil printing unit 3. The first stencil printing unit 3 prints an image on one surface of the conveyed paper P as described above.

  Next, the reversing device 73 sends the paper P with one printed surface facing upward, along the arc-shaped locus while sucking the other surface, so that one surface faces downward. Then, it is conveyed toward the inside of the storage unit 4 while being reversed. The paper P thus sequentially conveyed is carried into the storage unit 4 while the carry-in device 74 sucks and holds the upper surface, that is, the other surface.

  After the paper P is temporarily stored in the storage unit 4, the carry-out device 81 carries out the paper P from the storage unit 4. The pick-up roller 82 sequentially picks up the paper P thus carried out and conveys it to the timing roller 83. The timing roller 83 sequentially conveys the paper P at a predetermined timing and sends it to the second stencil printing unit 5.

  The second stencil printing unit 5 prints an image on the upper surface, that is, the other surface of the conveyed paper P as described above. Subsequently, the discharge device 84 conveys the paper P with the other printed surface facing upward to the discharge table 6 while sucking and holding the one surface. As described above, the paper P on which double-sided printing has been completed is sequentially stacked on the paper discharge tray 6.

  In the conventional double-sided stencil printing apparatus having the basic configuration as described above, the printing area on the paper P by the second stencil printing unit 5 may fluctuate in the vertical direction, as described above. FIG. 3 schematically illustrates this. In other words, in this example, the printing area Q with a solid line should be originally set at the substantially central portion of the paper P, but actually the area Q moves in the vertical direction (in this case, toward the “heaven” side) as indicated by a broken line. May end up.

  The double-sided stencil printing apparatus 1 of the present embodiment can prevent the occurrence of this problem. Hereinafter, this point will be described in detail. FIG. 4 is a block diagram showing a configuration for preventing the fluctuation of the print area. The operation panel 90 is disposed on, for example, the upper surface of the apparatus housing 10 illustrated in FIG. 1, and a control unit 91 is connected to the operation panel 90. The control unit 91 is connected to the first sensor S1 and the second sensor S2 described above, and is also connected to a table reference unit 92. And the output of the control part 91 is input into the motor drive circuit 93 which drives the said motor M1.

Hereinafter, the operation of the configuration of FIG. 4 will be described. Table 1 below shows the results of measuring the fluctuation of the printing area when the printing apparatus was operated without the configuration of FIG. 4 functioning. Here, as an example, the first drum 31 and the second drum 51 having an outer diameter of 173 mm are set to “first speed (= 60 rpm)”, “second speed (= 80 rpm)”, and “third speed (= 100 rpm)”. Three printings were performed at each speed. Then, as an index indicating the position of the printing area, the length (mm) of the margin on the “top” side of the paper after printing, that is, the front side in the paper conveyance direction, was measured and is shown in Table 1. The “margin” mentioned below is all on the “heaven” side.

  In the case 40 of the storage unit 4 shown in FIG. 2, 12 sheets of paper P are stored, and in each printing, printing was continuously performed on 20 sheets of paper P more than that. . When such printing is performed, as shown in Table 1, there is a clear difference in length between the margin on the first to eighth sheets P and the margin on the ninth to twentieth sheets P. . The leftmost column in Table 1 shows the sheet order of how many sheets are counted from the beginning, and the rows marked “1-8” in the column are 1-8 sheets. The average value for the 9th sheet and the line “9-20” indicate the average value for the 9th to 20th sheets.

  The above-described difference in the margin length is considered to be due to the reason described above. That is, when printing is performed on the first to eighth sheets P by the second drum 51, printing is performed in parallel on the first drum 31, whereas the ninth to twentieth sheets (the last one) When printing is performed on the first to twelfth paper P counted from the paper, printing on the first drum 31 has already been completed, and the second drum 51 is printing alone. This is because the load of the motor M2, which is a drum driving source, is different in both cases. Here, the former printing process by the second drum 51 is referred to as a parallel printing process, and the latter printing process is referred to as a single printing process. More specifically, in the case of a single printing process compared to the parallel printing process. The load on the motor M2 is reduced. Normally, there is a backlash between the second drum 51 arranged so as to be able to be pulled out with respect to the printing apparatus main body and its driving mechanism. However, when the load of the motor M2 becomes small as described above, the amount of shift of this backlash Will change. Then, the drum angle is shifted to the top, and the margin becomes shorter.

  In the present embodiment, control is performed so that the margin length in the case of the parallel printing process is standard, and the margin length in the case of the single printing process is matched with the standard margin length. For this purpose, the difference between the measured margin lengths in both cases was obtained (displayed in the “difference” row in Table 1), and the average was obtained for each printing speed. That is, for example, in the case of “1st speed”, an average value of 0.7 mm is obtained from the differences of 0.6 mm, 0.7 mm, and 0.8 mm. Similarly, in the case of “2nd speed”, the average value of 0.7 mm is obtained, and “3 In the case of “speed”, an average value of 0.5 mm was obtained. These average values indicate an appropriate adjustment amount of the relative position in the transport direction of the sheet P with respect to the stencil sheet 51a of the second drum 51.

  More specifically, the average values “0.7 mm”, “0.7 mm”, and “0.5 mm” indicate appropriate adjustment amounts in the case of the single printing process, and are respectively “1st speed” and “2nd speed”. ”And“ 3rd speed ”and further stored in a storage means such as a memory in the table storage unit 92 of FIG. 4 in the form of a table associated with“ single print processing ”. On the other hand, in the present embodiment, since the margin length in the case of the parallel printing process is set as a standard, the appropriate adjustment amount “0 mm” is stored in the storage unit in the form of a table associated with “parallel printing process”.

  When performing double-sided printing, the size and thickness of the paper P used for double-sided printing, as well as the number of prints and the printing speed are set by operating the operation panel 90. Regarding the printing speed, any one of the above-mentioned “1st speed”, “2nd speed” and “3rd speed” is selected and set, and the printing speed set here (that is, the paper conveyance speed) is set. Information indicating Sv is input to the control unit 91. Information indicating the number of printed sheets Sn is also input to the control unit 91.

  The control unit 91 also receives paper detection signals F1 and F2 output each time the first sensor S1 and the second sensor S2 detect one paper P. The first sensor S1 constitutes the paper counting means in the present invention. Based on the sheet detection signal F1 of the first sensor S1, the control unit 91 determines the number of sheets of the sheet P to be sent to the second drum 51 in the series of printing in which the conditions are set on the operation panel 90. Determine if it exists. In other words, this sheet order is the order of the order of counting when the case 40 of the storage unit 4 is empty.

  Based on the sheet order determined as described above, the information indicating the number of printed sheets Sn input from the operation panel 90 as the number-of-printing-setting means, and the design storage number of the storage unit 4, the control unit 91 will It is determined whether the paper P sent to the two drums 51 is subjected to parallel printing processing or single printing processing. That is, for example, when the design storage number of the storage unit 4 is 12 and the series of prints is 30, the first to 18th sheets P are subjected to the parallel printing process, and the order is 19 to 30. It can be determined that the first sheet P is subjected to a single printing process.

  The controller 91 receives the drive command signal Sd basically when a predetermined time T has elapsed since the paper detection signal F3 output when the second drum reference sensor S3 is turned on (paper detection). By sending it to the drive circuit 93, the paper refeed is controlled so that the paper P is sent to a predetermined position in the transport direction with respect to the stencil paper 51a on the second drum 51. The setting of the conveyance speed in this case is called default setting. However, even in such a case, the print area Q on the paper P may fluctuate due to the reasons described above.

  Therefore, when the control unit 91 determines that the sheet P to be sent to the second drum 51 is to be subjected to the parallel printing process, the control unit 91 stores the appropriate value stored in association with the “parallel printing process” in the table storage unit 92. When the adjustment amount “0 mm” is read, and on the other hand, it is determined that the sheet P to be sent to the second drum 51 is to be subjected to the single print process, the table storage unit 92 associates it with “single print process”. The stored appropriate adjustment amount “0.7 mm”, “0.7 mm”, or “0.5 mm” is read out, and an appropriate adjustment is made to the predetermined time T so that the appropriate adjustment amount is set. In the latter case, one of the appropriate adjustment amounts “0.7 mm”, “0.7 mm”, and “0.5 mm” is selected based on the information indicating the printing speed Sv input from the operation panel 90. Read out. That is, when the printing speed is “1st speed” or “2nd speed”, the appropriate adjustment amount “0.7 mm” stored in the table storage unit 92 is read in association therewith, and the printing speed is “3rd speed”. ", The appropriate adjustment amount" 0.5 mm "stored in the table storage unit 92 in association with it is read out.

  Therefore, when the control unit 91 determines that the paper P sent to the second drum 51 is to be subjected to the parallel printing process, the predetermined time T is left as it is based on the appropriate adjustment amount “0 mm”. On the other hand, if it is determined that the paper P sent to the second drum 51 is to be subjected to the single printing process, the control unit 91 may obtain an appropriate adjustment amount “0.7 mm” or “0.5 mm”. The predetermined time T is shortened by a predetermined amount ΔT.

  By adjusting the predetermined time T in this way, the drive start timing of the motor M1, that is, the timing roller 83 is changed. FIG. 5 shows this change. As shown here, the sheet conveyance speed by the timing roller 83 is basically set to a relatively high speed v1 in the first half of the conveyance period, and after the speed v1 is maintained for a predetermined time, the sheet speed is lower than that. It is set to v2 according to the conveyance speed of the two drums 51. Printing by the second drum 51 is performed on the paper conveyed at the low speed v2. If the predetermined time T is shortened and the drive start timing of the motor M1 is advanced as shown by the broken line in the drawing while maintaining the basic change pattern of the sheet conveyance, the sheet P is moved to the second drum 51 earlier. Therefore, the relative position in the transport direction of the paper P with respect to the stencil sheet 51a is shifted to the front side.

  This state is easily shown in FIG. In the figure, (1) shows the relationship between the paper P and the printing area Q by the stencil sheet 51a when the default setting is made, and (2) shows the same relationship when the driving start timing of the motor M1 is changed early. Show. As shown here, in the case of (2) compared to the case of (1), the relative position of the paper P shifts to the front side, in other words, the printing area Q shifts to the rear side, and the margin increases. The time width ΔT is set so that the margin increase amount is 0.7 mm when the printing speed is “1st speed” or “2nd speed”, and the margin increase amount is when the printing speed is “3rd speed”. It is set to be 0.5 mm. By doing so, as shown in Table 1, when the second stencil printing unit 5 performs the single printing process, it is compensated that the margin is shortened as compared with the case of performing the parallel printing process. The positions of the print areas in the processing can be made common, that is, the margin lengths can be made common.

  The value of the time width ΔT that realizes the desired margin increase amount can be obtained in advance based on experiments and experience. Therefore, the appropriate time width ΔT thus obtained is associated with the margin increase amount and stored in the memory or the like of the control unit 91, and the time width ΔT corresponding to the obtained margin increase amount is read out, You may make it apply it to control. Further, this time width ΔT is indirectly shown as an appropriate adjustment amount of the relative position in the transport direction of the paper P with respect to the stencil sheet 51a, and is associated with “parallel printing processing” and “single printing processing”, and the table storage unit 92 The time width ΔT associated with each printing process may be read out and applied to the control.

  In Table 1 described above, the margin length of the first sheet among the first to eighth sheets is shorter than the other sheets of the second to eighth sheets. This is because printing was performed only by the first drum 31 until immediately before the paper P arrives at the second drum 51, and therefore the load of the motor M2 is light and the rotation speed of the second drum 51 is increased. It is thought that it remains at the time of printing. Therefore, in order to eliminate the variation of the printing area Q due to this point, an appropriate adjustment amount different from that for the second to eighth sheets may be set particularly for the first sheet. .

  Further, in the present embodiment, the motor drive start timing when the second stencil printing unit 5 performs parallel printing processing is set as a default setting, and when performing single printing processing, the predetermined time T is shortened. On the other hand, the motor drive start timing in the case of single print processing is set as a default setting, and in the case of parallel print processing, it is possible to align the positions of the print areas Q in both print processing by extending the predetermined time T. It is. For reference, in FIG. 5, a change state of the sheet conveyance speed when the predetermined time T is extended is indicated by a one-dot chain line. Further, the change of the printing area Q at that time is shown in (3) of FIG.

  Further, when the second stencil printing unit 5 performs parallel printing processing, the predetermined time T is extended, and when performing single printing processing, the predetermined time T is shortened so that the printing area Q in both printing processing is reduced. It is also possible to align the positions, that is, the lengths of the margins in common.

  In the present invention, instead of changing the driving start timing of the timing roller 83 driven by the motor M1 as described above, the position of the printing region Q is changed by changing the average conveying speed of the timing roller 83 within a predetermined period. It is also possible to adjust. Hereinafter, such a case will be described with reference to FIGS. 4 and 7.

  The second sensor S2 shown in FIGS. 4 and 1 is used to determine the timing for switching the sheet conveyance speed by the timing roller 83 shown in FIG. 7 from v1 to v2. In other words, as indicated by the solid line in the figure, the switching is performed when the time Ta has elapsed after the second sensor S2 detects the leading edge of the paper P (this is referred to as default setting in this case). This default setting is applied when the printing process performed by the second stencil printing unit 5 is a parallel printing process, as described above.

  On the other hand, when the printing process performed by the second stencil printing unit 5 is a single printing process, the control unit 91 in FIG. 4 further includes a predetermined time in addition to the time Ta as shown by a broken line in FIG. The switching is performed after ΔT1 has elapsed. By doing so, the average transport speed by the timing roller 83 within a predetermined period (for example, the period from the start of driving of the timing roller 83 to the start of printing) is increased compared to the case of default setting. In this case, therefore, the position of the print area Q on the paper P changes from that shown in FIG. 6 (2), assuming that the default setting is that shown in FIG. 6 (1). That is, also in this case, the margin of the paper P becomes longer.

  In order to make the margin shorter as opposed to the above, the time point at which the conveyance speed is switched from v1 to v2 is set earlier than the time Ta in the default setting, as shown by a one-dot chain line in FIG. As a result, the average transport speed by the timing roller 83 within the predetermined period is reduced as compared with the default setting. In this case, therefore, the position of the print area Q on the paper P changes from that shown in FIG. 6 (3) if the default setting is that shown in FIG. 6 (1).

  In order to change the average conveyance speed by the timing roller 83 within the predetermined period, in addition to the above, the value of v1 may be increased or decreased while keeping the period of speed v1 constant. Good.

  Further, in the embodiment described above, the control unit 91 uses the design storage number of the storage unit 4, the number of printed sheets set by the operation panel 90 as the print number setting unit, and the sheet counted by the first sensor S <b> 1 as the sheet counting unit. Based on the order of P, it is configured to determine whether the printing process performed by the second stencil printing unit 5 for the paper P in that order is a parallel printing process or a single printing process. However, the two types of printing processes may be determined by other methods. For example, for example, a photoelectric paper detection unit for detecting whether or not the paper P is present on the first drum 31 is provided, and the output is input to the control unit 91, and the control unit 91 is based on the output. It is also possible to configure to perform the above determination.

  As mentioned above, although embodiment applied to the double-sided stencil printing apparatus 1 was described, this invention is not restricted to it, While being provided with a 1st printing means, a paper storage part, and a 2nd printing means, a paper is taken from a storage part. The present invention can also be applied to other printing apparatuses provided with a refeeding means that is transported to the second printing means, for example, a multicolor printing apparatus that does not have a paper reversing unit. It plays. That is, even in the printing apparatus having such a configuration, when the paper printed by the first printing unit is temporarily stored in the storage unit and then transported to the second printing unit, the above-described change in the printing region is performed. Therefore, the occurrence of such a problem can be prevented by applying the present invention.

  Further, when the present invention is applied to the double-sided stencil printing apparatus, the printing apparatus is not limited to the apparatus of the above-described embodiment. For example, a scanner unit that reads an image of a document or a scanner unit is provided above the apparatus housing 10. A stencil making unit for perforating a stencil sheet based on the stencil image data generated based on the image data of the read document image may be provided.

DESCRIPTION OF SYMBOLS 1 Double-sided stencil printing apparatus 2 Paper feed stand 3 1st stencil printing part (1st printing means)
4 Paper storage section 5 Second stencil printing section (second printing means)
6 Paper Discharge Stand 7 Paper Feed Unit 8A First Intermediate Transport Unit 8B Second Intermediate Transport Unit (Refeed Unit)
9 Paper discharge unit 10 Device housing 31 First drum (paper transport unit)
31a Stencil paper 32 First press roller 51 Second drum (paper transport section)
51a Stencil sheet 52 First press roller 73 Inversion device 74 Carry-in device 82 Pickup roller 83 Timing roller (printing position adjusting means)
90 Operation panel (number of copies setting means)
91 Control Unit 92 Table Storage Unit 93 Motor Drive Circuit S1 First Sensor (Paper Counting Unit)
S2 Second sensor S3 Second drum reference sensor M1, M2 Motor P Paper Q Print area

Claims (1)

A first printing means for printing on one surface of the paper while the paper is pressed against the printing plate and conveyed;
A paper storage unit for temporarily storing the printed paper; and
A second printing means for printing on one surface or the other surface of the paper while the paper is pressed against the printing plate and conveyed;
A paper refeeding means for transporting the paper printed on the one surface from the paper storage section to a second printing means;
A printing apparatus comprising a common drive source for driving the respective sheet conveying sections of the first and second printing means;
A printing position adjusting means for adjusting a relative position of the paper in the conveyance direction with respect to the printing plate in the second printing means;
When the printing process performed by the second printing unit is a parallel printing process performed in parallel with the printing by the first printing unit, the appropriate adjustment amount of the relative position, and the printing process performed by the second printing unit Storage means for storing the appropriate adjustment amount of the relative position in association with each printing process, in the case of the single printing process only by the second printing means,
It is determined whether the printing performed on each sheet in the second printing means is the parallel printing process or the single printing process, and the appropriate adjustment amount associated with the determined printing process is stored in the memory. And a control means for setting the read adjustment amount in the printing position adjustment means.

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