JP2013063573A - Inkjet printer - Google Patents

Abstract

To provide an ink jet printing machine that increases the ink droplet landing accuracy and suppresses the generation of ink mist by controlling the size of the main ink droplet when printing on the edge of the paper. Is an issue.
An ink jet printing machine includes an ink jet head and a control unit that controls the size of ink main droplets of the ink jet head when ink is ejected from the ink jet head. The control unit includes a control unit that controls the size of the main ink droplet in the printable end portion 16 of the interleaf L according to the distance from the printable ends 18m and 18s.
[Selection] Figure 5

Description

  The present invention relates to an inkjet printer that controls main droplets discharged from an inkjet head.

  When printing a plurality of data or a large amount of printed matter, the printed matter discharged from the printing machine is stacked, but the separation of the printed matter for each data / number of sheets is not known. For this reason, conventionally, it has been made easier to understand the separation of printed matter by inserting offset paper into the separation of data and data and the separation of the number of sheets. In addition, by printing on the offset portion of the slip sheet, it is possible to know what the divided data is.

  By the way, due to the configuration of the ink jet printer, the offset portion of the slip sheet is the end portion of the paper. For this reason, if printing is performed on the offset portion of the slip sheet, the influence of the disturbance is large, causing the landing deviation of the main droplets and the occurrence of ink mist, and the stain on the printing surface and the printing press.

  As a countermeasure against this, Patent Document 1 proposes suppressing landing deviation by reducing the number of small dot diameters when ink is ejected to the edge of the paper.

JP 2005-022404

  However, in the proposal of Patent Document 1, it is expected that when ink is ejected to the edge of the sheet, only a large dot diameter is ejected, thereby preventing landing deviation from disturbance and improving image formation quality. Although it is possible, an increase in the amount of ink mist generated by discharging a large dot diameter cannot be suppressed. On the other hand, in order to reduce the amount of ink mist generated, it is necessary to reduce the size of the main droplet, but if it is reduced, the landing deviation of the main droplet will increase. Note that this may occur in the same manner even when printing on ordinary recording paper.

  The present invention has been made in view of the above problems, and by controlling the size of the main droplet of ink when printing on the edge of the paper, the landing accuracy of the ink droplet can be increased, and the ink mist can be improved. It is an object of the present invention to provide an ink jet printer that suppresses generation.

  In order to achieve the above object, a first feature of an ink jet printer according to the present invention is that at least one ink jet head and a printable end in a printable end portion of printing paper when ink is ejected from the ink jet head. Control means for controlling the size of the main ink droplet according to the distance from the ink.

  A second feature of the ink jet printer according to the present invention is that a printing condition when printing on a slip sheet as the printing paper is input to the control means.

  A third feature of the ink jet printer according to the present invention is that the control means controls the size of the main ink droplets according to the conveyance speed of the slip sheet.

  A fourth feature of the ink jet printing machine according to the present invention is that the control means controls the size of the ink main droplet in accordance with the head gap between the ink jet head and the slip sheet.

  A fifth feature of the ink jet printing machine according to the present invention is that a plurality of the ink jet heads are provided so that inks of different colors can be ejected, and the ink is printed with different colors for each interleaf. The control means controls to minimize the number of ink types ejected from the ink jet head onto the slip sheet.

  According to the first feature of the ink jet printer according to the present invention, landing deviation can be reduced by enlarging the ink main droplets near the printable end where the influence of disturbance is large, and the ink mains as the distance from the printable end increases. Since the generation of ink mist can be reduced by making the droplets small, it is possible to provide an ink jet printing machine with high ink droplet landing accuracy and suppressed ink mist generation.

  According to the second feature of the ink jet printer according to the present invention, it is possible to generate ink mist without causing a problem in the accuracy of printing on the slip sheet by using the fact that the readability of the slip sheet is not required so much. Can be efficiently suppressed.

  According to the third feature of the ink jet printer according to the present invention, the size of the main ink droplet is made larger as the transport speed is faster and is less susceptible to disturbance, and the main ink droplet is made smaller as the transport speed is slower. By suppressing the occurrence of ink mist, it is possible to further reduce the occurrence of ink mist while further suppressing the landing deviation of the ink main droplet.

  According to the fourth feature of the ink jet printer according to the present invention, the size of the ink main droplet is increased as the head gap is increased, and the size of the ink main droplet is decreased as the head gap is decreased. It is possible to further reduce the occurrence of ink mist while further suppressing landing deviation.

  According to the fifth feature of the ink jet printer according to the present invention, by setting the number of ink jet heads used for ejection to a minimum, the possibility of producing a head with a small ejection amount is reduced, thereby reducing the main droplets. The occurrence of mist can be further suppressed while further preventing landing deviation.

It is explanatory drawing which shows schematic structure of the inkjet printing machine which concerns on 1st Embodiment. It is a block diagram explaining the composition of the ink jet printer concerning a 1st embodiment. It is a top view explaining printing on the offset part of a slip sheet with the ink jet printer concerning a 1st embodiment. It is a perspective view which shows the loading state of the recording paper discharged | emitted from the inkjet printer which concerns on 1st Embodiment. It is explanatory drawing explaining changing printing conditions for every area | region of a printable edge part, when printing on a slip sheet with the inkjet printer which concerns on 1st Embodiment. It is explanatory drawing explaining changing printing conditions for every area | region when printing in the corner | angular part of the printable area | region of a slip sheet with the inkjet printer which concerns on 1st Embodiment. It is explanatory drawing explaining the printing conditions memorize | stored in the inkjet printer which concerns on 2nd Embodiment with a data table. It is explanatory drawing explaining the printing conditions memorize | stored in the inkjet printer which concerns on 3rd Embodiment with a data table. It is explanatory drawing explaining the printing conditions memorize | stored in the inkjet printer which concerns on 4th Embodiment with a data table. It is a flowchart figure explaining operation | movement of the inkjet printing machine of 5th Embodiment.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following description, the same or similar components as those already described are denoted by the same or similar reference numerals, and detailed description thereof is omitted as appropriate.

  In the following description, an example in which the number of ink drops is controlled when printing on a slip sheet will be described. However, the present invention is not limited to a slip sheet and can be applied to a case of printing on a normal recording sheet. Further, any size paper can be used as the recording paper.

  In addition, it should be noted that the drawings are schematic and the dimensional ratios and the like are different from actual ones. Therefore, specific dimensional ratios and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  The following embodiments are exemplifications for embodying the technical idea of the present invention, and the embodiments of the present invention are described below in terms of the material, shape, structure, arrangement, etc. of the components. It is not something specific. The embodiments of the present invention can be implemented with various modifications without departing from the scope of the invention.

[First Embodiment]
First, the first embodiment will be described.

(overall structure)
FIG. 1 is an explanatory diagram showing a schematic configuration of an ink jet printing machine according to the present embodiment. FIG. 2 is a block diagram illustrating the configuration of the ink jet printing machine according to the present embodiment. FIG. 3 is a plan view for explaining printing on the offset portion of the slip sheet by ink jet printing according to the present embodiment. FIG. 4 is a perspective view showing a stacked state of recording sheets discharged from the ink jet printer according to the present embodiment. FIG. 5 is an explanatory diagram for explaining that the printing condition is changed for each region of the printable end portion when printing on the slip sheet by the ink jet printer according to the present embodiment. FIG. 6 is an explanatory diagram for explaining that the printing condition is changed for each area when printing is performed at the corner of the printable area of the slip sheet by the ink jet printer according to the present embodiment.

  As shown in FIG. 1, the ink jet printing machine 101 according to the present embodiment includes a paper feed unit (not shown), a printer unit 102, a belt platen mechanism unit 104, and a recording paper transport unit 105 inside and outside a casing 100. (See FIG. 2), a control unit 10, and a paper discharge unit (not shown). The ink jet printing machine 101 of this embodiment is a line type ink jet printer.

  With this configuration, the transported recording paper S is sucked and transported by the fan of the belt platen mechanism unit 104, and an image is formed by ink droplets ejected by the printer unit 102.

  Then, as shown in FIG. 4, the printed material N on which the normal recording paper S discharged from the paper discharge unit is stacked is composed of a plurality of data so that the data delimiter can be recognized, or the number delimiter can be determined. By inserting a slip sheet L (for example, slip sheet L1 or slip sheet L2 in FIG. 4) offset in the front-back direction or the right-and-left direction with respect to the transport direction, the separation of data of the printed matter N can be known. Further, by forming an image P (see FIG. 3) at the offset portion of the inserted slip sheet L, it is possible to know the divided data information.

(Printer part)
The printer unit 102 is installed on the downstream side of the paper feeding unit and on the upstream side of the recording paper circulation conveyance path unit, and is fixed to the housing 100 at a substantially central portion in the housing 100.

  In the printer unit 102, a plurality of line-type inkjet heads 31 (hereinafter simply referred to as heads 31) corresponding to a plurality of colors of ink are used for C (cyan) and K (black) from the upstream side toward the downstream side. , M (magenta) and Y (yellow). That is, from the upstream side toward the downstream side, the cyan head 31C, the black head 31K, the magenta head 31M, and the yellow head 31Y are arranged in this order.

  The heads 31 of the respective colors are attached to the head holder 32 and are arranged at equal intervals in the conveyance direction X of the recording paper S by the belt platen mechanism unit 104. Each head 31 has a discharge surface 31F formed on the lower surface side, and ink of each color is discharged from each discharge surface.

  The head holder 32 is provided with a head gap adjusting unit 33 that suspends and supports the belt platen mechanism 104 so as to be lifted and lowered. The head gap adjustment unit 33 includes a head gap adjustment mechanism having a pulley and a wire, and a motor. The belt platen mechanism 104 that is connected to the wire and supported by being suspended is moved up and down by rotating the pulley by the motor and winding and unwinding the wire. Therefore, the belt platen mechanism 104 is structurally separated from the housing 100.

  The head gap adjustment unit 33 is connected to the control unit 10 as a part of the printer unit 102 and is driven by the control of the control unit 10. The belt platen mechanism 104 is moved up and down by the head gap adjusting unit 33, for example, when the print mode is changed according to the type of the recording paper S. As an example, when a printing mode for printing on a paper whose thickness is larger than that of plain paper (for example, an envelope) is selected, the control unit 10 lowers the belt platen mechanism unit 104 so that the head 31 and the belt The case where the space | interval with the belt conveyance path 41R (henceforth only conveyance path 41R) formed of the below-mentioned conveyance belt 41 of the platen mechanism part 104 is expanded more than usual is mentioned.

  Further, when ink is selectively ejected from a plurality of nozzles (not shown) provided in the head 31, in the ink jet system, a driving signal is applied to each piezoelectric element provided corresponding to each nozzle, and the diaphragm A piezo method in which the ink in the ink reservoir chamber is ejected from the nozzle by displacing the ink, an electrostatic method in which the drive signal is applied to the electrostatic gap to displace the diaphragm and the ink in the ink reservoir chamber is ejected from the nozzle, There is a film boiling ink jet method in which ink is ejected from a nozzle by pressure change caused by bubbles generated by heating the ink with a micro heater in the reservoir chamber, and any method may be used in the present invention. In this embodiment, a piezo method having a simple structure and good reliability is applied.

  When the piezo method is applied to the head 31, in the head 31, a plurality of nozzles are formed on the nozzle plate at a density of 300 nozzles per inch (300 dpi) along the main scanning direction (Y-axis direction). In addition, each ink reservoir chamber for temporarily storing ink IK corresponding to each nozzle is formed with both sides surrounded by partition walls.

  In addition, a plurality of piezo elements are fixed to each nozzle on a diaphragm facing the nozzle plate and the ink reservoirs.

  Therefore, for example, when a drive signal is applied to one piezo element arranged second from the left in the drawing, the diaphragm is displaced toward one nozzle corresponding to one piezo element, so one piezo element and one nozzle Ink IK is ejected from one nozzle when a volume change occurs in one ink reservoir corresponding to the above.

(Control part)
As shown in FIG. 2, the control unit 10 includes therein a calculation unit (CPU) 13 a, a ROM 13 b that stores control software for the ink jet printer 101, and information that can be changed during operation of the ink jet printer 101. Are temporarily stored, and a table 13d for storing information of a plurality of heads 31 provided in the inkjet printer 101 is provided. The diameter of the ink droplet (main droplet) ejected from the head 31 is adjusted by the control unit 10 adjusting the displacement and displacement speed of the diaphragm.

  As shown in FIGS. 5 and 6, in this embodiment, when printing on the offset portion of the slip sheet L, ink droplets are printed in the printable end portion 16 of the slip sheet L according to the distance from the printable end 18. The table 13d stores printing conditions that define the number of ink drops so that the control unit 10 can change the size of the ink drop.

  Specifically, as shown in FIG. 5, when printing is performed on an offset portion parallel to the transport direction (hereinafter referred to as sub-scanning direction offset portion 22s), and an offset portion orthogonal to the transport direction (hereinafter referred to as main scanning direction). The printing condition 24 ms for printing on the offset portion 22m) is stored in the table 13d. Further, as shown in FIG. 6, the printing condition 24e for printing at the intersection of the sub-scanning direction offset portion 22s and the main scanning direction offset portion 22m (hereinafter referred to as the slip-sheet corner offset portion 22e) is stored in the table 13d. Stored.

  In the present embodiment, when printing in the printable end portion 16, the printable end 18 (printable end 18 s parallel to the sub-scanning direction offset portion 22 s or parallel to the main scanning direction offset portion 22 m is used under the printing condition 24 ms. If the distance from the printable edge 18m) is 0 to A, the number of drops is 6 times, the number of drops is 5 times for the area A to Ax2, and the number of drops is Ax2 to Ax3. The number is set to 4 times. The printing condition 24e is a reasonable condition for the slip sheet corner offset portion 22e, as will be described later. The value of A is set in advance according to the type of the slip sheet L, the specifications of the inkjet printer 101, the printing conditions, and the like.

  Here, the larger the number of ejections, the larger the size of the main droplet. Therefore, the printing conditions 24 ms and 24 e make it possible to reduce landing deviation by increasing the ink droplets near the printable end 18 where the influence of disturbance is large, and to reduce the ink droplets as the distance from the printable end 18 decreases. Generation of ink mist due to droplets can be reduced.

(Belt platen mechanism)
The belt platen mechanism unit 104 is disposed below the heads 31 so as to face the printer unit 102.

  In the belt platen mechanism unit 104, a plurality of unprinted recording sheets S fed by a sheet feeding unit or a single side transported by a circulation transport path JR described later are transported while being loaded with printed recording sheets S. An endless belt-like transport belt (belt platen) 41 having a suction hole (not shown) is stretched between a drive pulley 72 and a driven pulley 73 that are driven to rotate by a motor. A conveyance path 41 </ b> R is formed by the conveyance belt 41. The transport path 41R constitutes a part of a later-described circulation transport path JR.

  The moving speed of the conveying belt 41 by the motor, that is, the conveying speed of the recording paper S by the conveying belt 41 can be detected by the control unit 10 by the output of the encoder. Between the driving pulley 72 and the driven pulley 73, a suction fan 74 for generating a negative pressure for sucking the recording paper S onto the conveying belt 41 is provided.

  The conveyor belt 41 has a plurality of suction holes (not shown) communicating with the above-described suction fan 74 arranged on the back side thereof. A suction force generated by the suction fan 74 is supplied to the suction hole. Therefore, a suction force toward the transport belt 41 due to the negative pressure of the suction hole blocked by the recording paper S acts on the recording paper S on the transport belt 41.

  In the belt platen mechanism 104, when the recording paper S is mounted on the belt-like transport belt 41, the recording paper S is sucked by air through the suction holes on the transport belt 41, and the recording paper S is transported by the transport belt 41. The recording paper S is transported in the transport direction X (sub-scanning direction) by the rotation of the transport belt 41 while being fixed on the top. The recording sheet S being transported is printed in full color by a plurality of heads 31 of the printer unit 102 disposed above the passage path.

(Function, effect)
Hereinafter, the operation and effect of this embodiment will be described. The ink jet printer 101 determines whether or not printing on the slip sheet L is necessary when printing, and performs normal print control when it is not necessary to print on the slip sheet L. When it is necessary to print on the slip sheet L, the print processing on the slip sheet L is performed on the printable end portion 16 by controlling the number of ink drops for each region. Here, the number of drops is uniform on the inner side of the printable edge 16 than the printable edge 16, and the printable edge 16 is an area where the number of drops gradually changes from the printable edge 18.

  In the present embodiment, it is determined which of the printing conditions 24 ms and 24 e is applied to each region of the printable edge 16 of the slip sheet L.

  Specifically, as described above, when printing is performed on the sub-scanning direction offset portion 22s and the main scanning direction offset portion 22m in the printable end portion 16, as shown in FIG. 18 (the printable end 18s, 18m) in the region where the distance is 0 to A, the number of ink drops is 6 times, and in the region where the distance from the printable end 18 is A to A × 2, the printable end is 5 times. In the region where the distance from 18 is A × 2 to A × 3, it is set to 4 times.

  When printing is performed on the slip sheet corner offset portion 22e of the printable end portion 16, the distance from the printable ends 18m and 18s is defined as follows. As shown in FIG. 6, in the region where the distance from the printable end 18m is 0 to A and the distance from the printable end 18s is also 0 to A, the number of drops is six. In the region where the distance from one of the printable ends 18m and 18s is 0 to A and the distance from the other is A to A × 2, the number is 5 times. The distance from the printable end 18m is A to A × 2, and the distance from the printable end 18s is also 4 times in the region of A to A × 2. Even in a region where the distance from one of the printable ends 18m and 18s is 0 to A and the distance from the other is A × 2 to A × 3, the number is 4 times. In the region where the distance from one of the printable ends 18m and 18s is A to A × 2 and the distance from the other is A × 2 to A × 3, the number is 3 times. The distance from the printable end 18m is A × 2 to A × 3, and the distance from the printable end 18s is also twice in the region of A × 2 to A × 3.

  In this way, by setting the printing conditions 24 ms and 24 e according to each area of the slip sheet L in consideration of the number of ink drops according to the distance from the printable ends 18 m and 18 s of the slip sheet L, the disturbance can be reduced. By increasing the number of drops and enlarging the ink main droplets near the printable end 18 having a large influence, the landing deviation can be reduced, and as the distance from the printable end 18 is increased, the number of drops is decreased and the ink main droplets are reduced. Generation of ink mist can be reduced. Therefore, it is possible to obtain the ink jet printing machine 101 with high ink droplet landing accuracy and suppressed generation of ink mist, and dirt on the printing surface and the printing machine is reduced.

  In addition, since the interleaving paper L does not require much readability of printing, the present embodiment can efficiently suppress the occurrence of ink mist without causing a problem in the printing accuracy on the interleaving paper L.

  In this embodiment, the example in which four types of inks C (cyan), M (magenta), K (black), and Y (yellow) are ejected has been described, but printing is performed with one color (for example, K). In this case, the number of the heads 31 provided in the inkjet printer 101 may be one.

[Second Embodiment]
Next, a second embodiment will be described. The present embodiment is an example in which the control unit 10 further controls the ink main droplet size by controlling the number of ink drops on the slip sheet L according to the conveyance speed of the slip sheet L, as compared with the first embodiment. FIG. 7 is an explanatory diagram showing a data table stored in the ink jet printer according to the present embodiment, and shows the relationship between the conveyance speed of the recording paper S and the number of ink drops.

  In the present embodiment, the table 13d of the control unit 10 also stores the print condition 26 shown in FIG. 7 in addition to the print condition 24ms shown in FIG. 5 and the print condition 24e shown in FIG. Then, as shown in FIG. 7, when the conveyance speed of the recording paper S is slow, the number of drops is a maximum of four times, and when the conveyance speed of the recording paper S is medium, the maximum is five times. When the conveying speed of S is fast, the controller 10 controls the number of times so that it is 6 times at the maximum. In addition, when a conveyance speed is slow, it is a case where thick things, such as thick paper, are conveyed, for example, when a conveyance speed is medium, it is a case where an envelope is conveyed, for example, when conveyance speed is high, it is thin paper etc. This is a case of transporting thin objects.

  When the conveyance speed of the interleaving paper L, which is a printing target paper, is high, the influence of disturbance on the ink droplets ejected from the head 31 increases, so the ink droplet size is increased in order to reduce the landing deviation of the ink droplets. There is a need to. On the other hand, when the transport speed is slow and the influence of disturbance is small, even if the size of the ink main droplet is reduced, the landing accuracy does not drop so much.

  For this reason, in this embodiment, as the transport speed is faster, the maximum drop number is increased and the size of the ink main droplet is increased to make it less susceptible to disturbance. As the transport speed is slower, the maximum drop number is increased. Is reduced to reduce the size of the main ink droplets, thereby suppressing the occurrence of ink mist. Accordingly, it is possible to further reduce the occurrence of ink mist while further suppressing the landing deviation of the ink main droplet.

[Third Embodiment]
Next, a third embodiment will be described. This embodiment is an example in which the control unit 10 further controls the relationship between the head gap G, which is the distance between the ejection surface of the head 31 and the recording sheet S, and the number of ink drops, as compared to the first embodiment. FIG. 8 is an explanatory diagram showing a data table stored in the ink jet printer according to the present embodiment, and shows the relationship between the head gap and the number of ink drops.

  In the present embodiment, the table 13d of the control unit 10 stores the printing condition 28 shown in FIG. 8 in addition to the printing condition 24ms shown in FIG. 5 and the printing condition 24e shown in FIG.

  The head gap G changes depending on the thickness of the recording paper S. As the head gap G increases, the flying distance of ink droplets increases and the influence of disturbances tends to increase.

  In this embodiment, as shown in FIG. 8, the larger the head gap G, the larger the number of drops and the larger the main ink droplet size, and the smaller the head gap G, the smaller the number of drops and the smaller main ink droplet size. As a result, the occurrence of ink mist is further reduced while further suppressing the landing deviation of the ink main droplets.

[Fourth Embodiment]
Next, a fourth embodiment will be described. The present embodiment is an example in which the control unit 10 further controls the relationship between the number of interleaf sheets L and the number of ink drops that need to be distinguished from each other when printing compared to the first embodiment. In the present embodiment, the number of slip sheets L distinguished from each other is the number of slip sheets L to be inserted into the printed material N. FIG. 9 is an explanatory diagram for explaining the printing conditions stored in the ink jet printer according to the present embodiment using a data table, and is printed on the number of inserted slip sheets L and the offset portion of the slip sheets L. The relationship with the ink color is shown in a table.

  In the present embodiment, the table 13d of the control unit 10 also stores the print condition 30 shown in FIG. 9 in addition to the print condition 24ms shown in FIG. 5 and the print condition 24e shown in FIG.

  In order to form an image other than the color unique to the head, it is necessary to mix the discharge liquid of each head 31. For this reason, there is a possibility that a head with a small discharge amount may be generated, which may lead to landing deviation of the main droplet and generation of mist. When printing on the slip sheet L, the necessity of using various colors is small because it is only necessary to know the data delimiter and what the data is. For this reason, it is preferable to perform monochromatic ejection as much as possible for printing of the offset portion.

  For this reason, in the present embodiment, the number of heads 31 used for ejection is set to a minimum according to the number of slip sheets L to be printed. That is, for up to four interleaving papers L, four types of inks of C (cyan), M (magenta), K (black), and Y (yellow) are printed independently, thereby enabling discrimination by color. On the 5th and 6th sheets, printing is performed with a mixture of two color liquids such as C and M, thereby enabling discrimination by color. Therefore, by reducing the possibility of producing a head with a small discharge amount, it is possible to further suppress the occurrence of mist while further suppressing the landing deviation of the main droplet. Even when seven or more sheets of interleaving paper L are printed, printing is performed with a mixture of two color liquids in the same manner, and after using all combinations of the two color liquids, the three color liquids are mixed. You may print with things.

[Fifth Embodiment]
Next, a fifth embodiment will be described. The present embodiment is an example of an ink jet printer that has all the functions of the ink jet printer described in the first embodiment, the second embodiment, and the fourth embodiment. That is, the ink jet printing machine according to the present embodiment has the functions of the ink jet printing machine 101 described in the first embodiment, as well as the conveyance speed and the number of drops of the recording paper S as described in the second embodiment. It further has a function of controlling the relationship and a function of minimizing the number of heads 31 used for ejection according to the number of interleaf sheets L to be printed, as described in the fourth embodiment.

  FIG. 10 is a flowchart for explaining the operation of the ink jet printer according to the present embodiment.

  In the present embodiment, the control unit determines whether or not printing on the slip sheet L is necessary when printing (step S1). If it is not necessary to print on the slip sheet L, normal print control is performed (step S2).

  If it is necessary to print on the slip sheet L, it is determined whether the printed matter on the slip sheet L is a single color or a plurality of colors (step S3). If it is determined that the color is a single color, the color to be ejected is determined based on the printing condition (for example, printing condition 30; see FIG. 9) in the table 13d depending on the type of interleaving paper L to be inserted (step S4).

  Then, whether it is a single color or a plurality of colors, it is determined whether the conveyance speed of the interleaving paper L, which is a printing object, is high speed, medium speed, or low speed (step S5). When the speed is low, the main droplet size is set to a small value (step S6). When the speed is medium, the main droplet size is set to medium (step S7). When the speed is high, the main droplet size is set. Is set to a large value (step S8). In step S8, for example, the determination is made based on the printing condition 26 in the table 13d. In any case, the number of ink drops depending on the printing position is controlled (step S9), and the printing process is performed (step S10). In step S9, for example, the determination is made based on the printing conditions 24ms and 24e (see FIGS. 5 and 6) of the table 13d.

  Thereafter, the presence / absence of the next printing is determined (step S11). If it is necessary to perform the next printing, the process returns to step S1, and if it is not necessary to perform the next printing, the printing is terminated.

  According to the present embodiment, the function of controlling the size of the main ink droplet according to the distance from the printable ends 18m and 18s of the slip sheet L and the function of controlling the size of the main ink droplet according to the transport speed of the slip sheet L. In addition, an ink jet printer that has all the functions of minimizing the number of heads 31 to be used according to the number of interleaf sheets L to be printed is realized.

  In the present embodiment, the example in which the first embodiment, the second embodiment, and the fourth embodiment are combined has been described. However, it is of course possible to combine the third embodiment.

10 Control unit (control means)
16 Printable edge 18 Printable edge 18s Printable edge 18m Printable edge 24ms Print condition 24e Print condition 26 Print condition 28 Print condition 30 Print condition 31 Head (inkjet head)
31C head (inkjet head)
31K head (inkjet head)
31M head (inkjet head)
31Y head (inkjet head)
101 Inkjet printing machine G Head gap L Interleaf

Claims (5)

At least one inkjet head;
Control means for controlling the size of the ink main droplets according to the distance from the printable end in the printable end of the printing paper when ejecting ink from the inkjet head;
An ink jet printing machine comprising:   2. The ink jet printer according to claim 1, wherein a printing condition when printing on a slip sheet as the printing paper is input to the control unit.   The inkjet printer according to claim 2, wherein the control unit controls the size of the main ink droplet according to the conveyance speed of the slip sheet.   The ink jet printing machine according to claim 2, wherein the control unit controls the size of the main ink droplet according to a head gap between the ink jet head and the slip sheet. A plurality of the inkjet heads are provided so that different color inks can be ejected,
3. The control unit according to claim 2, wherein the control unit controls so as to minimize the number of ink types ejected from the inkjet head onto the slip sheet when printing with different colors for each slip sheet. Inkjet printing machine.

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