JP2006264026A - Inkjet printer - Google Patents

Abstract

The present invention makes it possible to clean an ink jet head without moving the ink jet head, and to achieve both a reliable conveyance and cleaning of a print medium.
First and second inkjet heads 2 and 3 are disposed above first and second transport units 4 and 5, respectively, and a plurality of endless belts are provided in the first and second transport units 4 and 5, respectively. 6 and 7 are disposed at intervals, and the first and second cleaning caps 12 and 13 disposed between the endless belts 6 and 7 are moved up and down to clean the heads 2 and 3. The endless belts 6 and 7 are provided with wide portions 6w and 7w having a wide width and narrow portions 6n and 7n having a narrow width, respectively, and the print medium 1 is adsorbed and reliably conveyed by the wide portions 6w and 7w having a wide width. Then, the first and second inkjet heads 2 and 3 are cleaned by moving the first and second cleaning caps 12 and 13 between the narrow narrow portions 6n and 7n.
[Selection] Figure 1

Description

  The present invention relates to an ink jet printer which draws predetermined characters and images by discharging and outputting fine particles (dots) of liquid ink of a plurality of colors onto a print medium, for example.

Such an inkjet printer is generally inexpensive and can easily obtain a high-quality color printed matter. Accordingly, along with the widespread use of personal computers and digital cameras, it has become widespread not only in offices but also in general users.
In such an ink jet printer, generally, a moving body called a carriage or the like that is integrally provided with an ink cartridge and an ink discharge head (generally called an ink jet head) moves on a print medium in a direction perpendicular to the feeding direction. By driving the actuator while reciprocating, the fine particles of the liquid ink are ejected (jetted) from the nozzles formed in the ink jet head, thereby outputting minute ink dots on the print medium, and predetermined characters and images Is drawn to create a desired printed matter. The carriage is equipped with four color (yellow, magenta, cyan) ink cartridges including black (black) and an inkjet head for each color, so that not only monochrome printing but also full-color printing combining each color is easy. (Furthermore, 6 colors, 7 colors, or 8 colors in which light cyan, light magenta, etc. are added to these colors are also put into practical use).

 In addition, in an ink jet printer that performs printing while reciprocating the ink jet head on the carriage in the direction perpendicular to the print medium feeding direction (width direction of the print medium), the entire page is printed neatly. In order to achieve this, it is necessary to reciprocate the inkjet head several tens to 100 times or more. Therefore, the printing time is significantly longer than that of other types of printing apparatuses such as laser printers and copying machines using electrophotographic technology. There is such a drawback.

  On the other hand, in an inkjet printer of a type in which a long inkjet head having the same dimensions as the width of the print medium is arranged and a carriage is not used, it is not necessary to move the inkjet head in the width direction of the print medium, so-called one pass. Therefore, high-speed printing similar to that of the laser printer is possible. The former inkjet printer is generally referred to as a “multi-pass printer”, and the latter inkjet printer is generally referred to as a “line head printer”.

 By the way, in this type of ink jet printer, since the nozzle is always in contact with the outside air during the printing operation, the nozzle that does not output ink is dried and deteriorated, the ink nozzle is clogged, and the ink nozzle It is easy to cause deterioration of print quality due to adhesion or intrusion of paper dust on the ink jet, and it is necessary to clean the ink jet head. Therefore, conventionally, the cleaning process position of the inkjet head is set to a position different from the position during the normal printing operation, and the inkjet head is moved to that position to perform the cleaning process.

 However, when continuous printing is performed, if the printing operation is temporarily interrupted and the ink jet head is moved to the cleaning position and returned to the printing position after the cleaning process, there is a problem that the printing time becomes long. Particularly, in the line head type printer, since the ink jet head is large, the efficiency reduction is remarkable. In the line head type printer, the distance for moving the large inkjet head to the cleaning position is long, and the ink nozzle dries during this long movement, and the stable output of the ink may be hindered.

Therefore, in the inkjet printer described in Patent Document 1 listed below, the inkjet head is rotated to a non-printing area where no ink is output from a nozzle on a plane parallel to the printing medium, and the cleaning process is performed in the non-printing area. There is something to do.
JP 2002-103638 A

However, even in the ink jet printer described in Patent Document 1, there is no change in moving a large line type ink jet head, even if there is a difference between rotational movement and parallel movement. Various problems such as leakage of ink droplets, increase in moving time, enlargement of the apparatus, or reproducibility of positioning accuracy occur.
The present invention has been made paying attention to the above-described problems, and the inkjet head cleaning process can be performed without moving the inkjet head, and the conveyance of the print medium and the cleaning process can be compatible. An object of the present invention is to provide a possible ink jet printer.

  [Invention 1] In order to solve the above-mentioned problem, an inkjet printer of Invention 1 is provided with a plurality of endless belts arranged in a direction intersecting the conveyance direction of the printing medium, and the printing medium is disposed on the outer peripheral surface of these endless belts. An inkjet head in which nozzles for ejecting ink droplets are formed between a plurality of endless belts of the conveyance unit; a plurality of the conveyance units on the opposite side of the inkjet head across the conveyance unit; And a cleaning unit that cleans the inkjet head, and the plurality of endless belts include a wide wide part for transporting the print medium, and the cleaning unit. Thus, the ink jet head has at least two narrow width portions and a narrow narrow width portion for cleaning the ink jet head.

  The ink jet head referred to in the present invention refers to an ink droplet output portion in which nozzles for ink output used in, for example, an ink jet printer are formed. By using a known electrostatic method, piezo method, film boiling ink jet method, etc., fine particle ink droplets are used. Are generically used to form minute round ink dots by ejecting the ink onto a printing medium such as recording paper. Also, examples of the printing medium conveying method include a method using a spur and a roller, and a method in which the belt is charged and the printing medium is adsorbed by electrostatic force. Ink jet heads are generally cleaned by reducing the negative pressure near the nozzle surface and sucking ink.

 According to the ink jet printer according to the first aspect of the present invention, the cleaning unit disposed between the endless belts on the opposite side of the ink jet head and between the endless belts of the transport unit with the transport unit interposed between the endless belts of the transport unit. Since the nozzles of the disposed inkjet head can be cleaned, the inkjet head can be cleaned without moving the inkjet head, and a plurality of endless belts are provided with a wide portion and a narrow portion. Therefore, if the inkjet head is cleaned by moving the cleaning section between the narrow width sections and supporting the print medium, the print medium can be reliably transported. And the cleaning process can be made compatible.

[Invention 2] The ink jet printer according to Invention 2 is the ink jet printer according to Invention 1, comprising a belt position detecting means for detecting the position of the endless belt of the transport unit, and a transport and cleaning unit for the print medium by the transport unit. Control means for controlling the cleaning of the ink jet head, and the control means is arranged such that when the narrow portions of the plurality of endless belts detected by the belt position detecting means are on the print medium conveying surface, the endless ones thereof The belt is stopped and the ink jet head is cleaned by the cleaning unit.
According to the ink jet printer according to the second aspect of the present invention, when the narrow portions of the plurality of endless belts are on the print medium conveyance surface, the endless belts are stopped and the ink jet head is cleaned by the cleaning unit. The inkjet head can be reliably cleaned by moving the cleaning portion between the narrow portions of the endless belt.

 [Invention 3] Further, the ink jet printer of Invention 3 is the ink jet printer of Invention 2, wherein the control means has wide portions of the plurality of endless belts detected by the belt position detecting means on the print medium conveying surface. Sometimes, printing is performed by ejecting ink droplets from the inkjet head while driving these endless belts.

 According to the ink jet printer according to the third aspect of the present invention, when the wide portions of the plurality of endless belts are on the print medium conveying surface, printing is performed by ejecting ink droplets from the ink jet head while driving the endless belts. Therefore, the print medium can be conveyed while being reliably supported by the wide portion of the endless belt, and thus, high-speed printing by, for example, one pass can be performed.

 [Invention 4] The ink jet printer according to Invention 4 is the ink jet printer according to Invention 2, wherein the control means has narrow width portions of the plurality of endless belts detected by the belt position detecting means on the print medium conveying surface. In some cases, flushing is performed by ejecting ink droplets from the inkjet head while driving these endless belts.

The flushing referred to in the present invention, for example, eliminates ink discharge instability due to drying of ink in nozzles at nozzles having a long non-discharge time (long discharge standby time). More specifically, the actuator is driven to eject ink droplets from the nozzles of the inkjet head toward the cleaning unit.
According to the ink jet printer according to the fourth aspect of the present invention, when the narrow portions of the plurality of endless belts are on the print medium conveying surface, the flushing is performed by ejecting ink droplets from the ink jet head while driving the endless belts. Therefore, for example, flushing can be performed before and after printing in the wide portion, thereby improving the operating rate.

Next, an embodiment of an inkjet printer according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of the ink jet printer of the present embodiment, FIG. 2a is a plan view thereof, and FIG. 2b is a front view thereof. In FIG. 1, a print medium 1 is a line head type ink jet printer that is conveyed in the direction of the arrow in the figure from the upper right to the lower left of the figure, and is printed in the printing area in the middle of the conveyance. However, the ink jet head of the present embodiment is arranged not only at one place but also at two places.

 Reference numeral 2 in the figure denotes a first inkjet head provided on the upstream side in the conveyance direction of the print medium 1, and reference numeral 3 denotes a second inkjet head provided on the downstream side, and below the first inkjet head 2. Is provided with a first transport unit 4 for transporting the print medium 1, and a second transport unit 5 is provided below the second inkjet head 3. The first transport unit 4 includes four first endless belts 6 arranged at predetermined intervals in a direction intersecting the transport direction of the print medium 1, and the second transport unit 5 is also a print medium. It is composed of four second endless belts 7 arranged at a predetermined interval in a direction crossing one transport direction.

 The four second endless belts 7 as well as the four first endless belts 6 are alternately arranged adjacent to each other. A driving roller 8 is disposed in the overlapping portion of the first endless belt 6 and the second endless belt 7, a first driven roller 9 is disposed on the upstream side, and a second driven roller 10 is disposed on the downstream side. It is installed. The first endless belt 6 is wound around the driving roller 8, the first driven roller 9 and the first auxiliary roller group 17, and the second endless belt 7 is wound around the driving roller 8, the second driven roller 10 and the second auxiliary roller group 18. An electric motor 11 is connected to the drive roller 8. Therefore, when the drive roller 8 is rotationally driven by the electric motor 11, the first transport unit 4 configured by the first endless belt 6 and the second transport unit 5 configured by the second endless belt 7 are synchronized with each other and the same. Move at speed. Incidentally, the first endless belt 6 is routed below the first cleaning cap 12 described later by the four auxiliary roller groups 17, and the second endless belt is positioned below the second cleaning cap 13 by the four auxiliary roller groups 18. Has been circulated.

 The first inkjet head 2 and the second inkjet head 3 are, for example, for each of six colors of yellow (Y), magenta (M), cyan (C), light magenta (Lm), light cyan (Lc), and black (K). In addition, the printing medium 1 is arranged so as to be shifted in the transport direction. Ink is supplied to each inkjet head 2 and 3 from an ink tank of each color (not shown) via an ink supply tube. Each of the inkjet heads 2 and 3 is formed with a plurality of nozzles in a direction intersecting the transport direction of the print medium 1, and printing is performed by ejecting a necessary amount of ink droplets from the nozzles to a necessary portion at the same time. A minute ink dot is formed and output on the medium 1. By performing this for each color, it is possible to perform so-called one-pass printing by passing the print medium 1 conveyed by the first conveyance unit 4 and the second conveyance unit 5 once. That is, the area where the inkjet heads 2 and 3 are disposed corresponds to the print area.

 As a method for discharging and outputting ink from each nozzle of the ink jet head, there are an electrostatic method, a piezo method, a film boiling ink jet method, and the like. In the electrostatic system, when a drive signal is given to the electrostatic gap, which is an actuator, the diaphragm in the cavity is displaced, causing a pressure change in the cavity, and ink drops are ejected from the nozzle by the pressure change. It is. In the piezo method, when a drive signal is given to a piezo element that is an actuator, the diaphragm in the cavity is displaced to cause a pressure change in the cavity, and an ink droplet is ejected from the nozzle by the pressure change. . In the film boiling ink jet method, there is a minute heater in the cavity, the ink is instantaneously heated to 300 ° C. or more, the ink is in a film boiling state, bubbles are generated, and ink droplets are ejected and output from the nozzles due to the pressure change. That's it. Any ink output method can be applied to the present invention.

 The ink droplet ejection nozzles of the first inkjet head 2 are formed only between the four first endless belts 6 of the first conveyance unit 4, and the ink droplet ejection nozzles of the second inkjet head 3 are second conveyance. It is formed only between the four second endless belts 7 of the portion 5. This is because the inkjet heads 2 and 3 are cleaned by a cleaning unit, which will be described later, but in this way, one-pass printing cannot be performed with only one of the inkjet heads. Therefore, the first ink jet head 2 and the second ink jet head 3 are arranged so as to be shifted in the transport direction of the print medium 1 in order to compensate for the portions that cannot be printed with each other.

 Disposed below the first inkjet head 2 is the first cleaning cap 12 for cleaning the first inkjet head 2, and disposed below the second inkjet head 3 is the second inkjet head. 2 is a second cleaning cap 13 that cleans 3. Each of the cleaning caps 12 and 13 is provided between the four first endless belts 6 of the first transport unit 4 (more precisely, between the narrow portions 6n described later) and the four of the second transport unit 5. It is formed in a size that can pass between the second endless belts 7 (precisely, between narrow portions 7n described later). As a representative of these cleaning caps 12 and 13, the configuration of the first cleaning cap 12 for cleaning the first inkjet head 2 is shown in FIG.

 The first cleaning cap 12 covers a nozzle 52 formed on the nozzle surface 51 of the first inkjet head 2 and is disposed on the bottom thereof, and has a rectangular bottomed cap body 53 that can be in close contact with the nozzle surface 51. The ink absorber 54, a tube 55 connected to the bottom of the cap body 53, and a lifting device (not shown) are connected to a negative pressure generating device such as a tube pump (not shown). The first cleaning cap 12 is raised by a lifting device (not shown), and the cap body 53 is in close contact with the nozzle surface 51 of the first inkjet head 2. In this state, when the inside of the cap body 53 is made negative pressure by the negative pressure generating device, ink droplets and bubbles are sucked out from the nozzles 52 provided on the nozzle surface of the first ink jet head 2, and the first ink jet head 2. Can be cleaned. When the cleaning is completed, the first cleaning cap 12 is lowered. The configuration of the second cleaning cap 13 is the same as this. In some cases, the meniscus of each nozzle may be adjusted by stroking the nozzle surface with a wiper.

 Returning to FIGS. 1 and 2, on the upstream side of the first driven roller 9, there are two pieces that adjust the paper feed timing of the print medium 1 supplied from the paper feed unit and correct the skew of the print medium 1. A pair of gate rollers 14 is provided. The skew is a twist of the print medium 1 with respect to the transport direction. Further, on the downstream side of the second driven roller 10, a spur 15 and a paper discharge roller 16 for discharging the print medium 1 from the print area are disposed.

 A first belt charging device 19 is disposed on the upstream side of the first cleaning cap 12 in the print medium conveyance direction so as to face the first endless belt 6 routed by the auxiliary roller group 17. . A second belt charging device 20 is disposed on the upstream side of the second cleaning cap 13 in the print medium conveyance direction so as to face the second endless belt 7 routed by the auxiliary roller group 18. . These belt charging devices 19 and 20 are constituted by discharge devices such as corotron, for example, and charge the first and second endless belts 6 and 7, respectively. In general, these belts are composed of a medium / high resistance body or an insulator. Therefore, when charged by a belt charging device, the charge applied to the surface is also composed of a high resistance body or an insulator. The print medium 1 is caused to generate dielectric polarization, and the print medium 1 can be adsorbed to the belt by electrostatic force generated between the charge generated by the dielectric polarization and the charge on the belt surface. The charging unit may be a charging roller to which a constant voltage is applied, for example.

 A photoelectric first belt position sensor 21 that detects the position of the first endless belt 6 from the width of the first endless belt 6 of the first transport unit 4 is provided below the first cleaning cap 12. Yes. Further, a photoelectric second belt position sensor 22 that detects the position of the second endless belt 7 from the width of the second endless belt 7 of the second transport unit 5 is provided below the second cleaning cap 13. Yes. The first and second belt position sensors 21 and 22 are not limited to the photoelectric type, and contact type sensors may be used. Further, instead of directly detecting the width of the belt, for example, an encoder provided on the belt may be read.

 Then, the belt position information of the first and second endless belts 6 and 7 of the first and second belt position sensors 21 and 22 is input to the printer control unit 23. The printer control unit 23 is configured to include an arithmetic processing unit such as a computer system, for example, drive control of the first and second continuously variable belts 6 and 7, drive control of the first and second inkjet heads 2 and 3, Drive control of the first and second cleaning caps 12 and 13 is performed. Note that the printer control unit 23 only needs to have a function of performing arithmetic processing, and may be constructed with so-called application software. It is also possible to load and construct application software on a personal computer connected to the inkjet printer. Moreover, you may construct | assemble with the hardware which has an equivalent function.

 Therefore, according to this ink jet printer, the surface of the first endless belt 6 of the first transport unit 4 is charged by the first belt charging device 19, and the print medium 1 is fed from the gate roller 14 in this state, not shown. When the print medium 1 is pressed against the first endless belt 6 by a paper pressing roller constituted by a spur or a roller, the print medium 1 is attracted to the surface of the first endless belt 6 by the action of the dielectric polarization described above. In this state, when the drive roller 8 is rotationally driven by the electric motor 11, the rotational driving force is transmitted to the first driven roller 9 via the first endless belt 6, and the print medium 1 is moved downstream in the transport direction. .

 The first endless belt 6 and the auxiliary transport belt 18 are moved downstream in the transport direction while the print medium 1 is adsorbed in this manner, the print medium 1 is moved below the first ink jet head 2, and the first ink jet Printing is performed by ejecting ink droplets from the nozzles formed on the head 2. When printing by the first ink jet head 2 is completed, the print medium 1 is moved downstream in the transport direction and transferred onto the second endless belt 7 of the second transport unit 5. As described above, since the surface of the second endless belt 7 is also charged by the second belt charging device 20, the print medium 1 is pressed against the second endless belt 7 by a paper pressing roller including a spur and a roller (not shown). The print medium 1 is attracted to the surface of the second endless belt 7 by the action of the dielectric polarization described above.

 In this state, the second endless belt 7 is moved downstream in the conveying direction, the printing medium 1 is moved below the second inkjet head 3, and ink droplets are ejected from the nozzles formed in the second inkjet head 3. To print. When printing by the second inkjet head 3 is completed, the print medium 1 is further moved downstream in the transport direction, and the spur 15 and the paper discharge are performed while separating the print medium 1 from the surface of the second endless belt 7 by a separation device (not shown). The roller 16 discharges the print medium 1 to the paper discharge unit.

 When the first and second inkjet heads 2 and 3 need to be cleaned, the first and second cleaning caps 12 and 13 are raised as described above to raise the nozzle surfaces of the first and second inkjet heads 2 and 3. In this state, the cap body is brought into a negative pressure so that ink drops and bubbles are sucked out from the nozzles of the first and second ink jet heads 2 and 3 and cleaned. 2 Lower the cleaning caps 12 and 13.

 Incidentally, a plan view of the first and second endless belts 6 and 7 and the first and second cleaning caps 12 and 13 is, for example, as shown in FIG. This is such that the first endless belt 6 and the second endless belt 7 are adjacent to each other. For example, when the vertical dimension in the figure is defined as the width, the width of the first endless belt 6 and the second endless belt 6 are the same. If the width of the endless belt 7 is set to the same width, the maximum width that the both can take is obtained. As described above, since the nozzles of the first and second inkjet heads 2 and 3 are formed over the entire gap (full width) of the first and second endless belts 6 and 7, the first and second endless belts 6 and 7 cover them. The width of the second cleaning caps 12 and 13 is larger than the width of the gap between the first and second endless belts 6 and 7. That is, in this state, the first and second cleaning caps 12 and 13 cannot be brought into close contact with the nozzle surfaces of the first and second inkjet heads 2 and 3 beyond the positions of the first and second endless belts 6 and 7. .

 Therefore, in the present embodiment, as shown in FIGS. 5 and 6, for example, narrow first and second endless belts 6 and 7 are provided with narrow narrow portions 6n and 7n. The portions corresponding to the maximum width are relatively wide portions 6w and 7w. Therefore, as shown in FIG. 4, if the print medium 1 is sucked by the wide portions 6w, 7w of the first and second endless belts 6, 7, the print medium 1 can be sucked by a wider suction surface. Reliable conveyance is possible. Also, as shown in FIGS. 5 and 6, when the narrow portions 6n and 7n of the first and second endless belts 6 and 7 are on the print medium conveying surface, that is, the first and second inkjet heads 2 and 3 When it is between the first and second cleaning caps 12 and 13, the cleaning may be performed by raising and lowering the first and second cleaning caps 12 and 13.

 On the other hand, if the residual vibration of the actuator driven to eject ink droplets from the nozzles of the first and second inkjet heads 2 and 3 is detected from, for example, the back electromotive force of the switching element, the state of each nozzle is determined. It is known to be detectable. FIG. 7 shows the detection of residual vibration of the actuator. Depending on the state of the residual vibration, air bubbles are mixed in the nozzle, paper dust or dust is attached to the nozzle, nozzle clogging (drying), etc. Can be detected. Here, the paper dust refers to a fibrous material of print media made of wood pulp or an aggregate thereof, and is easily generated when it comes into frictional contact with, for example, a paper feed roller.

 When paper dust or dust adheres to the nozzle surface, the flight path is obstructed even when ink droplets are ejected, and the ink droplets collide with paper dust and penetrate and remain on the nozzle surface. If ink droplets are continuously ejected as they are, the ink droplets accumulate on the nozzle surface. In this case, it is effective to suck out ink from the nozzles using a cleaning cap and remove the causative paper dust. In addition, when the inkjet printer is not used for a long period of time, even if the cap is closely attached to the nozzle surface, the solvent component of the ink is gradually evaporated from the nozzle, and the concentration of the solid content of the ink is increased, resulting in clogging. Wake up. Minor clogging is recovered by forced ejection of ink droplets and the aforementioned flushing. For severe clogging, it is effective to forcibly suck out ink from the nozzles using a cleaning cap. Flushing is also effective for removing mixed colors.

 Therefore, as described above, whether or not cleaning or flushing is necessary can be determined based on the residual vibration of the ink droplet ejection actuator. Therefore, cleaning or flushing may be performed based on the determination result. In the cleaning, the first and second cleaning caps 12 and 13 need to be in close contact with the first and second ink jet heads 2 and 3 beyond the positions of the first and second endless belts 6 and 7. And the second endless belts 6 and 7 need to be stopped, and the flushing is performed by the first and second inkjet heads 2 and 2 toward the first and second cleaning caps 12 and 13 (the ink absorbers) immediately below them. Therefore, it is not necessary to stop the first and second endless belts 6 and 7.

 Therefore, the printer control unit 23 performs cleaning and flushing by performing the arithmetic processing of FIG. This calculation process is executed by, for example, a timer interrupt process every predetermined time. In this calculation process, first, in step S1, it is detected whether or not it is necessary to perform flushing by individual calculation process. If flushing is necessary, the process proceeds to step S7, and if not, the process proceeds to step S2. To do.

In step S2, it is determined whether or not it is immediately after the power switch is turned on. If it is immediately after the power switch is turned on, the process proceeds to step S7, and if not, the process proceeds to step S3.
In step S3, it is determined whether or not it is immediately before the printing operation. If it is immediately before the printing operation, the process proceeds to step S7, and if not, the process proceeds to step S4.

In step S4, it is determined whether or not it is immediately after the printing operation. If it is immediately after the printing operation, the process proceeds to step S7, and if not, the process proceeds to step S5.
In step S5, it is determined whether or not a printing failure has occurred. If a printing failure has occurred, the process proceeds to step S7, and if not, the process proceeds to step S6.
In step S7, the positions of the first and second endless belts 6 and 7 are detected by the first and second belt position sensors 21 and 22, and then the process proceeds to step S8.

 In step S8, among the first and second endless belts 6 and 7 detected in step S7, the narrow width portions 6n and 7n are printed medium conveying surfaces, that is, the first and second inkjet heads 2 and 3 and the first endless belts 6 and 7, respectively. It is determined whether or not it is positioned between the first and second cleaning caps 12 and 13, and when the narrow portions 6n and 7n are on the print medium conveyance surface, the process proceeds to step S9, and otherwise, the process proceeds to step S6. Migrate to

In step S9, whether or not cleaning is necessary is determined by individual calculation processing. If cleaning is necessary, the process proceeds to step S10, and if not, the process proceeds to step 15.
In step S10, after stopping the 1st and 2nd endless belts 6 and 7, it transfers to step S11.

In step S11, the first and second cleaning caps 12 and 13 are raised and then the process proceeds to step S12.
In step S12, negative pressure is generated in the first and second cleaning caps 12 and 13 to perform cleaning, and then the process proceeds to step S13.
In step S13, the pressure in the first and second cleaning caps 12 and 13 is released, and after that, the pressure is lowered and the process proceeds to step S14.

In step S14, the first and second endless belts 6 and 7 are driven and then the process returns to the main program.
In step S15, whether or not flushing is necessary is determined by individual calculation processing. If flushing is necessary, the process proceeds to step S16. If not, the process proceeds to step S6.

In step S16, without stopping the first and second endless belts 6 and 7, ink droplets are ejected from the first and second inkjet heads 2 and 3 to perform flushing, and then the process returns to the main program.
On the other hand, in step S6, the drive control of the first and second endless belts 6 and 7 and the print control by the first and second inkjet heads 2 and 3 are performed by individual calculation processing, and then the process returns to the main program.

 According to this calculation processing, the first and second endless belts 6 and 7 are attached to the first and second endless belts 6 and 7 immediately after the power switch is turned on, immediately before the printing operation, immediately after the printing operation, and when a printing failure occurs. After stopping, the first and second inkjet heads 2 and 3 are cleaned by the first and second cleaning caps 12 and 13. When flushing is necessary, flushing is performed by forcibly ejecting ink droplets from the first and second inkjet heads 2 and 3 while driving the first and second endless belts 6 and 7.

 As described above, according to the ink jet printer of the present embodiment, the first and second transport units 4 and 5 are disposed on the opposite side of the first and second transport heads 2 and 3 with the first and second transport units 4 and 5 interposed therebetween. The four first first and second transport units 4 and 5 are also provided by the first and second cleaning caps 12 and 13 disposed between the four first and second endless belts 6 and 7. Since the nozzles of the first and second inkjet heads 2 and 3 disposed between the second endless belts 6 and 7 can be cleaned, the first and second inkjet heads 2 and 3 are moved. In addition, the inkjet heads 2 and 3 can be cleaned, and each of the four first and second endless belts 6 and 7 includes two wide portions 6w and 7w and narrow portions 6n and 7n. Wide portions 6w, 7 The print medium 1 is supported and conveyed, and the first and second inkjet heads 2 and 3 are cleaned by moving the first and second cleaning caps 12 and 13 between the narrow portions 6n and 7n. By doing so, it is possible to achieve both reliable conveyance of the print medium 1 and cleaning processing.

 Further, when the narrow portions 6n and 7n of the four first and second endless belts 6 and 7 of the first and second transport units 4 and 5 are on the print medium transport surface, the endless belts 6 and 7 are provided. 7 is stopped, and the first and second inkjet heads 2 and 3 are cleaned by the first and second cleaning caps 12 and 13, so that the narrow width portions 6n and 6n of the first and second endless belts 6 and 7 are removed. The first and second cleaning caps 12 and 13 can be moved between 7 n to reliably clean the first and second inkjet heads 2 and 3.

 When the wide portions 6w, 7w of the four first and second endless belts 6, 7 of the first and second transport units 4, 5 are on the print medium transport surface, the endless belts 6, 7 are provided. The print medium 1 can be reliably secured by the wide portions 6w and 7w of the first and second endless belts 6 and 7 by printing ink by ejecting ink droplets from the first and second inkjet heads 2 and 3 while driving It can be conveyed while being supported, thereby enabling high-speed printing by, for example, one pass.

 Further, when the narrow portions 6n and 7n of the four first and second endless belts 6 and 7 of the first and second transport units 4 and 5 are on the print medium transport surface, the endless belts 6 and 7 are provided. By performing ink flushing by ejecting ink droplets from the first and second ink jet heads 2 and 3 while driving 7, for example, flushing can be performed before and after printing in the wide portions 6w and 7w. The rate can be improved.

In the ink jet printer of the present invention, the number of the first and second endless belts 6 and 7 constituting the first and second transport units 4 and 5 is not limited to the above. Further, the number of transport units is not limited to two.
Further, the method for transporting the print medium is not limited to the belt suction. For example, conveyance by a spur or a roller is also possible.

1 is a schematic configuration diagram illustrating an embodiment of an inkjet printer according to the present invention. FIG. 2 is a detailed explanatory view of the ink jet printer of FIG. 1, (a) is a plan view, and (b) is a front view. It is explanatory drawing of a cleaning cap. It is a top view of the endless belt and cleaning cap of FIG. It is a top view of the endless belt and cleaning cap of FIG. It is a top view of the endless belt and cleaning cap of FIG. It is explanatory drawing of the residual vibration of an actuator, and a nozzle state. 2 is a flowchart showing calculation processing performed in the printer control unit of FIG. 1.

Explanation of symbols

1 is a print medium, 2 is a first inkjet head, 3 is a second inkjet head, 4 is a first transport unit, 5 is a second transport unit, 6 is a first endless belt, 7 is a second endless belt, and 8 is driven Roller, 9 is a first driven roller, 10 is a second driven roller, 11 is an electric motor, 12 is a first cleaning cap, 13 is a second cleaning cap, 14 is a gate roller, 15 is a spur, 16 is a discharge roller, 17 is a first auxiliary roller group, 18 is a second auxiliary roller group, 19 is a first belt charging device, 20 is a second belt charging device, 21 is a first belt position sensor, 22 is a second belt position sensor, and 23 is Printer control unit

Claims (4)

  A plurality of endless belts are arranged in a direction intersecting the transport direction of the print medium, and a transport unit that transports the print medium on the outer peripheral surface of the endless belt, and a nozzle for ejecting ink droplets are provided in the transport unit. An inkjet head formed between a plurality of endless belts, and disposed on a side opposite to the inkjet head across the conveyance unit and between the plurality of endless belts of the conveyance unit, to clean the inkjet head A plurality of endless belts, the at least two endless belts including a wide wide part for transporting the print medium and a narrow narrow part for cleaning the inkjet head by the cleaning part. An ink jet printer having two width portions.   Belt position detecting means for detecting the position of the endless belt of the conveying section; and control means for controlling the conveyance of the printing medium by the conveying section and the cleaning of the ink jet head by the cleaning section, the control means comprising the belt When the narrow portions of the plurality of endless belts detected by the position detecting means are on the print medium conveyance surface, the endless belts are stopped and the inkjet head is cleaned by the cleaning unit. The inkjet printer according to claim 1.   The control means ejects ink droplets from the inkjet head while driving the endless belts when the wide portions of the plurality of endless belts detected by the belt position detecting means are on the print medium conveyance surface. The inkjet printer according to claim 2, wherein printing is performed.   The control means ejects ink droplets from the inkjet head while driving the endless belts when narrow portions of the plurality of endless belts detected by the belt position detecting means are on the print medium conveying surface. 4. The ink jet printer according to claim 2, wherein flushing is performed.

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