JP2007055107A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer capable of cleaning even at printing continuously while of stably conveying a printing medium. <P>SOLUTION: By the way of arranging a plurality of inkjet heads 1 along with the conveying direction of the printing medium 2, a cleaning unit 3 below each inkjet head 1 and a conveying roller 4 between the adjacent inkjet heads 1 and below the conveying path of the printing medium 2, and of conveying with catching the printing medium 2 by a spur 5 installed above the roller 4, the conveying belt itself is not required, so that the printing medium 2 can be stably conveyed, and also the cleaning gets able to be performed only by discharging ink toward the cleaning unit 3 or sucking the ink with the cleaning unit 3. The operation concerned is stabilized by arranging a printing medium guide 11 between the cleaning unit 3 and the conveying roller 4 and below the conveying path of the printing medium 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention, for example, an ink jet printer that prints predetermined characters and images by ejecting fine particles (ink droplets) of liquid ink of a plurality of colors from nozzles of an ink jet head and forming minute dots on a print medium. It is about.

Such inkjet printers are generally inexpensive and can easily obtain high-quality color prints, and therefore have become widespread not only in offices but also in general users with the spread of personal computers and digital cameras.
In general, such an ink jet printer reciprocates in a direction intersecting with the conveyance direction of a print medium by a moving body called a carriage integrally provided with an ink cartridge and an ink discharge head (generally called an ink jet head). However, by discharging (jetting) and outputting fine particles of liquid ink from the nozzles of the inkjet head, minute ink dots are formed on the print medium, and predetermined characters and images are drawn to create a desired printed matter. It has become. 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).

  Further, in this type of ink jet printer in which printing is executed while reciprocating the ink jet head on the carriage in a direction intersecting with the conveyance direction of the print medium, the ink jet head is set to 10 to cleanly print the entire page. Since it is necessary to reciprocate from several times to several tens of times, there is a disadvantage that it takes much printing time compared with other types of printing apparatuses such as laser printers and copying machines using electrophotographic technology.

  In contrast, in an inkjet printer of a type in which a long inkjet head (not necessarily integrated) having the same dimensions as the width of the print medium is disposed and the carriage is not used, the inkjet head is moved in the width direction of the print medium. This is not necessary, and so-called one-pass printing is possible, so that high-speed printing similar to the laser printer is possible. The former inkjet printer is generally referred to as a “multi-pass (serial) inkjet printer”, and the latter inkjet printer is generally referred to as a “line head inkjet printer”.

   By the way, in this type of ink jet printer, bubbles are generated in the cavity (pressure chamber) of the ink jet head, floating paper powder or dust adheres to the vicinity of the nozzle, or the nozzle (inner ink) dries. Then, ink droplets are not ejected from the nozzles, and dots may not be formed on the print medium. Ink droplet ejection failure is generally called “dot missing”. When a dot missing phenomenon occurs, recovery is performed by a cleaning device. For example, when a dot drop phenomenon occurs due to the generation of bubbles, the ink in the nozzle is sucked with a pump to discharge the bubbles inside the cavity, and then the ink attached to the nozzle surface is removed with a wiping member called a wiper. Wiping off and discharging the ink droplets called non-printing, called flushing, to discharge the mixed ink. This series of cleaning steps recovers the dot drop phenomenon due to bubbles.

Therefore, in the following Patent Document 1, in a line head type ink jet printer, an opening is formed in a transport belt that sucks and transports a print medium, and when the transport belt has an opening under the ink jet head, The recovery process is performed by ejecting ink toward the ink absorber provided below. Further, in the following Patent Document 2, in a line head type ink jet printer, a flatness restricting body, usually called a platen, which is disposed below the ink jet head and restricts the flatness of a print medium is made rotatable. An ink absorbing surface is formed on the opposite side of the flatness regulating surface. During normal printing, the flatness regulating surface regulates the flatness of the print medium, and it is rotated to eject ink when the ink absorbing surface is facing upward. Recovery process.
JP 2001-113690 A JP 2003-341158 A

  However, in the prior art described in Patent Document 1, since an opening must be formed in the transport belt, the strength of the transport belt is reduced, and the print medium cannot be stably transported. May be disturbed. Further, in the prior art described in Patent Document 2, the ink absorbing surface of the flatness regulating member faces downward during normal printing, so that the absorbed ink drops and becomes dirty, or the flatness regulating member is rotated. Therefore, there is a problem that the printing efficiency is lowered.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide an ink jet printer that can stably convey a print medium and that is free from fouling and reduced printing efficiency. Is.

  [Invention 1] In order to solve the above-described problems, the inkjet printer of Invention 1 is provided with a plurality of inkjet heads along the conveyance direction of the print medium, and a recovery process of the inkjet head is performed below each inkjet head. A cleaning unit is provided, and a conveyance roller is disposed between adjacent inkjet heads and below the conveyance path of the print medium.

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. Is generically used to form minute round ink dots by discharging the ink onto the recording paper.
According to the ink jet printer according to the first aspect of the present invention, a plurality of ink jet heads are disposed along the print medium conveyance direction, and a cleaning unit for performing recovery processing of the ink jet heads is disposed below each ink jet head. Since the conveyance roller is disposed between the adjacent inkjet heads and below the conveyance path of the print medium, the conveyance belt itself is not necessary, so that the print medium can be stably conveyed, Since the recovery process can be performed simply by ejecting the ink toward the cleaning unit or sucking the ink with the cleaning unit, the ink does not drop and become contaminated or the printing efficiency does not decrease.

[Invention 2] The inkjet printer of Invention 2 is characterized in that, in the inkjet printer of Invention 1, a spur is disposed above the conveying roller.
According to the ink jet printer according to the second aspect of the present invention, since the spur is disposed above the transport roller, the print medium can be transported with the transport roller and the spur being sandwiched, and the print medium can be transported more stably. It becomes possible to do.

[Invention 3] The inkjet printer of Invention 3 is characterized in that, in the inkjet printer of Invention 1 or 2, a print medium guide is disposed between the cleaning unit and the conveyance roller and below the print medium conveyance path. It is what.
According to the ink jet printer according to the third aspect of the present invention, the print medium guide is disposed between the cleaning unit and the transport roller and below the transport path of the print medium, so that even in the gap portion between the cleaning unit and the transport roller. Since the print medium can be guided by the print medium guide, the print medium can be transported more stably.

  [Invention 4] The ink jet printer of Invention 4 is the ink jet printer according to any one of Inventions 1 to 3, wherein a print medium entrance detection sensor is arranged on the entrance side of the most entrance ink jet head in the print medium transport direction, After the passage of the print medium is detected by the print medium entry side detection sensor, the inkjet head recovery process by each of the cleaning units is performed every predetermined time.

  According to the ink jet printer according to the fourth aspect of the present invention, after the passage of the print medium is detected by the print medium entrance detection sensor disposed on the entrance side of the ink jet head which is the most entrance in the print medium transport direction, the ink jets by the respective cleaning units are used. By performing the head recovery process every predetermined time, the inkjet head recovery process can be performed even when printing is continuously performed.

 [Invention 5] The inkjet printer according to Invention 5 is the inkjet printer according to Invention 4, wherein a print medium exit sensor is disposed on the exit side of the most exiting inkjet head in the print medium transport direction, and the print medium exit side is provided. The ink jet head recovery process is performed by each of the cleaning units after the detection sensor detects the front end of the print medium in the conveyance direction and the print medium entry side detection sensor detects the passage of the print medium. is there.

  According to the ink jet printer of the fifth aspect of the present invention, the front end portion of the print medium in the transport direction is detected by the print medium exit side detection sensor disposed on the exit side of the most out side ink jet head in the print medium transport direction. After the passage of the print medium is detected by the side detection sensor, the inkjet head recovery process is performed by each cleaning unit, so that the inkjet head recovery process can be reliably performed when printing is continuously performed.

[Invention 6] The inkjet printer according to Invention 6 is the inkjet printer according to any one of Inventions 1 to 5, wherein a paper feed roller is disposed on the input side in the print medium conveyance direction and a paper discharge roller is provided on the output side in the print medium conveyance direction. And the sheet feeding roller, the sheet discharging roller, and the conveying roller are driven by a single motor and a toothed belt.
According to the ink jet printer of the sixth aspect of the present invention, the paper feed roller is disposed on the input side in the print medium conveyance direction and the paper discharge roller is disposed on the output side in the print medium conveyance direction. Is driven by a single motor and a toothed belt, all the rollers are synchronized, the structure is simplified, and the cost can be reduced.

 [Invention 7] The ink jet printer according to Invention 7 is the ink jet printer according to any one of Inventions 1 to 5, wherein a paper feed roller is disposed on the input side in the print medium conveyance direction and a paper discharge roller is provided on the output side in the print medium conveyance direction. The sheet feeding roller, the sheet discharging roller and the conveying roller are driven by a single motor and gear.

  According to the ink jet printer of the seventh aspect of the invention, the paper feed roller is disposed on the input side in the print medium conveyance direction and the paper discharge roller is disposed on the output side in the print medium conveyance direction. Since the rollers are driven by one motor and gear, all the rollers are synchronized, the structure is simplified, and the cost can be reduced.

Next, a first embodiment of the inkjet printer of the present invention will be described with reference to the drawings.
FIG. 1A is a schematic front view of the ink jet printer according to the present embodiment, and FIG. 1B is a plan view thereof. Reference numeral 1 in the figure denotes an ink jet head for ejecting ink droplets, and black (K), cyan (C), magenta (M), yellow along the transport direction of the print medium 2, that is, the arrow direction shown in the figure. A total of four inkjet heads 1 are arranged at predetermined intervals in the order of (Y). Although the ink jet head 1 is integrated for each color, it is actually a combination of a plurality of ink jet blocks arranged in a staggered manner. For example, as shown in the cleaning unit 3 of FIG. An inkjet block for discharging droplets is laid out.

  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 ink droplets are 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 becomes a film boiling state, bubbles are generated, and ink droplets are ejected from the nozzle by the pressure change. That's it. Any ink output method can be applied to the present invention.

  Below each ink jet head 1, a cleaning unit 3 is disposed at a position covering a nozzle formed on the lower surface of each ink jet head 1, a so-called nozzle surface. As will be described later, the cleaning unit 3 includes a cap that is in close contact with the nozzle surface of the inkjet head 1, an ink absorber that is disposed in the cap and absorbs ink, a tube pump that creates a negative pressure in the cap, and the like. It is lifted up and down by a lifting device (not shown), and the cap is in close contact with the nozzle surface of the inkjet head 1 at the raised position. In the present embodiment, as described above, since the inkjet head 1 is a combination of a plurality of inkjet blocks arranged in a staggered manner, the cleaning units 3 are also staggered so as to correspond to the inkjet blocks. It is arranged.

  The print medium 2 is conveyed between the inkjet head 1 and the cleaning unit 3 in the direction of the arrow in the figure, and during that time, ink droplets are ejected from the inkjet head 1 to perform so-called one-pass printing. A two-dot chain line in the figure is a conveyance path for the print medium 2. A conveyance roller 4 for conveying the print medium 2 is disposed between the inkjet heads 1 and below the conveyance path for the print medium 2. Yes. A spur 5 is disposed above the transport roller 4. As will be described later, the spur 5 is for sandwiching the print medium 2 so as to press the transport roller 4 and transporting the print medium 2 in this state. In addition, the code | symbol 12 in a figure is the printing medium entrance detection sensor provided in the entrance side further from the inkjet head 1 of the conveyance direction entrance side (it means a near side) of the print medium 2, and the code | symbol 13 is This is a print medium outlet detection sensor provided further on the outlet side than the inkjet head 1 on the outlet side (meaning the front side) of the print medium 2. Each of these print medium detection sensors 12 and 13 is configured by an optical sensor, for example, and outputs a signal that is turned on only when the print medium 2 is passing.

  In addition, a paper feed roller 6 is disposed further on the entry side of the inkjet head 1 that is the most entry side in the conveyance direction of the print medium 2 and below the conveyance path of the print medium 2, and is the most exit side in the conveyance direction of the print medium 2. A paper discharge roller 7 is disposed on the further exit side of the inkjet head 1 and below the conveyance path of the print medium 2. A paper presser roller 8 is disposed above the paper supply roller 6. A spur 5 is also disposed above the paper discharge roller 7. Pulleys 20 are attached to the left ends of the conveyance roller 4, the paper supply roller 6, and the paper discharge roller 7 in the print medium conveyance direction, respectively. In addition, idlers 21 are disposed below the paper feed roller 6 and the transport roller 4, between the paper discharge roller 7 and the transport roller 4, and between the adjacent transport rollers 4. Further, a drive pulley 9 is disposed below the paper discharge roller 7, a tension pulley 22 is disposed in the vicinity thereof, and an idler 23 is disposed at a distance from the tension pulley 22. A series of toothed belts 10 are wound around the pulley 20 and idler 21, the drive pulley 9, the tension pulley 22 and the idler 23 of the transport roller 4, the paper feed roller 6 and the paper discharge roller 7. Since a motor (not shown) is connected to the drive pulley 9, when the drive pulley 9 is rotationally driven by this motor, the transport roller 4, the paper feed roller 6, and the paper discharge roller 7 connected by the toothed belt 10 slide. Without rotating, all rotate synchronously. The reason why the driving pulley 9 is disposed below the paper discharge roller 7 is that the toothed belt 10 wound around the conveying roller 4 is used for tension, and the belt is tensioned. This is because loosening is difficult to use. The reason why the idler 21 is disposed between the conveying rollers 4 is to secure the winding angle of the toothed belt 10.

  On the other hand, as described above, since the cleaning units 3 are arranged in a staggered manner corresponding to the ink jet blocks of the ink jet head 1, there is a gap between the cleaning unit 3 and the transport roller 4. In the present embodiment, the print medium guide 11 is disposed in the gap between the cleaning unit 3 and the transport roller 4. For example, as shown in FIGS. 2 and 3, the print medium guide 11 has a flat plate shape and is formed by bending the input side of the print medium 2 in the conveyance direction downward, and is individually supported by a support column 24. . The print medium guide 11 is for guiding the print medium 2 from below between the cleaning unit 3 and the transport roller 4, and is therefore disposed slightly below the transport path of the print medium 2.

  FIG. 2 shows details of a planar layout of the cleaning unit 3, the transport roller 4, and the print medium guide 11. In the present embodiment, since the cleaning units 3 are arranged in a staggered manner corresponding to the staggered ink jet blocks of the ink jet head 1, the gap between the transport roller 4 and the cleaning unit 3 is also staggered. Become. By disposing the print medium guide 11 in each of the staggered gaps, the print medium 2 does not have a guide only for the cleaning unit 3. However, since the cleaning unit 3 corresponding to each ink jet block itself is small, the print medium 2 to be conveyed does not become unstable just because there is no guide for the portion of the cleaning unit 3. The print medium 2 is stably conveyed by the conveyance roller 4 and the print medium guide 11 that guide most of the lower surface.

  FIG. 3 shows a cross section taken along the line AA of FIG. As described above, the cleaning unit 3 is disposed below each inkjet block of the inkjet head 1. The cleaning unit 3 is positioned below the conveyance path of the printing medium 2 in the normal printing state. During the recovery process of the inkjet head 1, it is lifted by a lifting / lowering device (not shown). For example, the cap 14 is brought into a negative pressure state with the cap 14 in close contact with the lower surface of the inkjet head 1, that is, the nozzle surface. Ink is sucked from the nozzle, for example, bubbles in the nozzle are sucked out. Such a recovery process of the inkjet head 1 is called cleaning, which is indispensable for stably discharging ink droplets from the nozzles.

  FIG. 4 shows details of the cleaning unit 3. The casing 53 of the cap 14 is moved up and down in the direction of the arrow in the figure, that is, in the up and down direction, by a lifting device (not shown). In addition, a coil spring 51 is interposed between the cap 14 and the housing 53, and when the housing 53 is raised, the cap 14 is attached to the lower surface of the inkjet head 1, that is, due to the elasticity of the coil spring 51. It is configured to be in close contact with the nozzle surface. Further, the bottom of the housing 53 is connected to the tube 56 of the tube pump 15. The tube pump 15 can generate a negative pressure with a relatively simple structure. In the tube pump 15, the rotating roller 55 generates a negative pressure by squeezing the flexible tube 56 disposed around the roller to move the fluid inside. For example, the ink accumulated in the cap 14 by the suction described above is sucked by the tube pump 4 and stored in the waste ink tank 52. Reference numeral 57 in the drawing is a liquid level sensor for detecting a full state of ink in the waste ink tank 52.

  A seal member 58 that is airtightly attached to the nozzle surface of the inkjet head 1 is attached to the upper end of the peripheral wall of the casing 53 of the cap 3. As the seal member 58, a material that has appropriate elasticity and hardly deteriorates even when in contact with ink is suitable. Examples thereof include silicon rubber and fluorine rubber. An ink absorbing member 60 is provided below the inkjet head 1. The ink absorbing member 60 is for absorbing ink sucked from the nozzles of the inkjet head 1. The ink absorbing member 60 is made of a material that easily absorbs the ink solvent and is preferably a porous material so as to easily absorb the ink. For example, in the case of water-based ink, a polyvinyl alcohol-based material can be used.

  Accordingly, the casing 53 of the cleaning unit 3 is lifted by a lifting / lowering device (not shown), and the cap 14 is closely attached to the inkjet head 1 so that the seal member 58 is closely attached to the nozzle surface, and the tube pump 15 is driven in this state. When the pressure in the cap 14 is reduced to a negative pressure, the ink is sucked from the nozzles of the inkjet head 1 and the inkjet head 1 can be recovered, that is, cleaned. The sucked ink is once absorbed by the ink absorbing member 60 and further discharged from the lower part of the housing 53 to the waste ink tank 52 through the tube 56 of the tube pump 15. Note that, during so-called flushing in which only ink droplets are preliminarily ejected without suction, it is not necessary to bring the cap 14 into close contact with the inkjet head 1, so that flushing may be performed without raising the housing 53.

   FIG. 5 shows details of the transport roller and the spur. The transport roller 4 is configured by covering the outer periphery of the mandrel 25 with an elastic body 26. The elastic body 26 is preferably made of a material having a large friction coefficient in order to convey the print medium 2, and for example, rubber or resin is used. The spur 5 is formed by forming a relatively sharp protrusion on the outer periphery of the disc as shown in the figure, and is mainly composed of resin or the like. The spur 5 is rotatably supported by an elastic shaft 27 made of, for example, a coil spring or a spring material, and is urged toward the conveying roller 4 by the elastic force of the elastic shaft 27. With the urging force applied to the spur 5, the printing medium 2 is sandwiched between the conveying roller 4 and in this state, the conveying roller 4 rotates as described above to convey the printing medium 2.

  FIG. 6 shows an example of the cleaning sequence in the present embodiment. In this cleaning sequence, first the print medium 2 is detected by the print medium entry side detection sensor 12, then the print medium 2 is detected by the print medium exit side detection sensor 13, and then the print medium entry side detection sensor 12 detects the print medium 2. The black (K) inkjet head 1 is cleaned at a predetermined time tc after a predetermined time t1 from the time when the passage of the ink is detected (the absence of the printing medium 2 is detected), and the cyan (C) inkjet is also performed after the predetermined time t2. The head 1 is cleaned at a predetermined time tc, the magenta (M) inkjet head 1 after the predetermined time t3 is cleaned at the predetermined time tc, and the yellow (Y) inkjet head 1 is also cleaned at the predetermined time t4. Clean at tc. The time difference between the predetermined times t1, t2, t3, and t4 is constant. By doing so, since the inkjet heads 1 can be sequentially cleaned immediately after the previous printing medium 2 has been printed, each inkjet head 1 can be cleaned even during continuous printing. In addition, after the print medium exit side detection sensor 13 detects the print medium 2 and the print medium entrance side detection sensor 12 detects passage of the print medium 2, each inkjet head 1 is cleaned. For example, it is possible to avoid cleaning when the print medium 2 is jammed in the middle of the conveyance path.

  As described above, according to the ink jet printer of the present embodiment, a plurality of ink jet heads 1 are arranged along the transport direction of the print medium 2, and the ink jet heads 1 are cleaned below each ink jet head 1. Since the cleaning unit 3 is disposed and the transport roller 4 is disposed between the adjacent inkjet heads 1 and below the transport path of the print medium 2, the transport belt itself is not required, so that the print medium 2 is stabilized. Can be transported, and cleaning can be performed simply by ejecting ink toward the cleaning unit 3 or sucking ink with the cleaning unit 3, so that ink can be dropped and stained or printed. There is no reduction in efficiency.

Further, since the spur 5 is disposed above the transport roller 4, the print medium 2 can be transported with the transport roller 4 and the spur 5 being sandwiched, and the print medium 2 can be transported more stably. It becomes possible.
Further, since the print medium guide 11 is disposed between the cleaning unit 3 and the transport roller 4 and below the transport path of the print medium 2, the print medium guide can be formed even in the gap between the cleaning unit 3 and the transport roller 4. 11 can guide the print medium 2, so that the print medium 2 can be transported more stably.

Further, after the passage of the print medium 2 is detected by the print medium entry side detection sensor 12 disposed on the entry side of the ink jet head 1 that is the most entry side in the conveyance direction of the print medium 2, By performing the cleaning every predetermined time, the inkjet head 1 can be cleaned even when printing is performed continuously.
In addition, the print medium exit side detection sensor 13 disposed on the exit side of the ink jet head 1 that is the most exit side in the transport direction of the print medium 2 detects the leading end of the print medium 2 in the transport direction, and the print medium entry side detection sensor 12. After the passage of the printing medium is detected in step 1, the inkjet head 1 is cleaned by each cleaning unit 3 so that the inkjet is surely performed when continuously printing except when the printing medium 2 is jammed. The head 1 can be cleaned.

Further, a paper feed roller 6 is disposed on the input side in the transport direction of the print medium 2 and a paper discharge roller 7 is disposed on the output side in the transport direction of the print medium 2, and the paper feed roller 6, paper discharge roller 7, and transport roller are disposed. Since 4 is driven by one motor and the toothed belt 10, all the rollers are synchronized, the structure is simplified, and the cost can be reduced.
The cleaning timing does not necessarily have to be during continuous printing. Specific examples include when the inkjet printer is not printing, when a series of printings are completed, before power is turned off, or when missing dots occur due to the generation of bubbles.

  Next, a second embodiment of the ink jet printer of the present invention will be described with reference to FIG. In this embodiment, pulleys 20 are mounted in two stages on the left end of the conveyance roller 4 in the print medium conveyance direction, and the pulley 20 of the conveyance roller 4 on the left side in FIG. 7 and the pulley 20 of the conveyance roller 4 in the center in the figure are toothed. The belt 10 is wound, and the individual toothed belt 10 is wound around the pulley 20 of the conveyance roller 4 in the center of the figure and the pulley 20 of the conveyance roller 4 on the right side of the figure. A separate toothed belt 10 is wound around the pulley 20. Then, an individual toothed belt 10 is further wound around the drive pulley 9, the tension pulley 22, the pulley 20 of the conveying roller 4 on the left side of FIG. 7 and the pulley 20 of the paper discharge roller 7, and all the rollers are rotated synchronously. . According to this belt application method, the conveyance belt 10 can be routed compactly, and the drive unit can be saved in space.

  Next, a third embodiment of the ink jet printer of the present invention will be described with reference to FIG. In this embodiment, the driven gear 17 is attached to the left end of the paper feed roller 6, the paper discharge roller 7, and the transport rollers 4 in the print medium transport direction, and the idle gear 28 is engaged between the driven gears 17. The specifications of all the driven gears 17 and the specifications of all the idle gears 28 are the same. Then, the drive gear 16 connected to a motor (not shown) is engaged with the driven gear 17 of the paper feed roller 6. Accordingly, when the drive gear 16 is rotationally driven by a motor (not shown), the transport roller 4, the paper feed roller 6, and the paper discharge roller 7 connected by the idle gear 28 and the driven gear 17 all rotate in synchronization without slipping. Thus, unlike the belt, the gear train can freely arrange the drive source, so that the structure can be simplified and the cost can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows 1st Embodiment of the inkjet printer of this invention, (a) is a front view, (b) is a top view. FIG. 2 is a detailed plan view of the ink jet printer of FIG. 1. It is AA sectional drawing of FIG. It is detail drawing of a cleaning unit. It is detail drawing of a conveyance roller and a spur, (a) is a longitudinal cross-sectional view, (b) is a left view. It is a timing chart which shows an example of a cleaning sequence. It is a schematic block diagram which shows 2nd Embodiment of the inkjet printer of this invention, (a) is a front view, (b) is a top view. It is a schematic block diagram which shows 3rd Embodiment of the inkjet printer of this invention, (a) is a front view, (b) is a top view.

Explanation of symbols

  1 is an inkjet head, 2 is a print medium, 3 is a cleaning unit, 4 is a transport roller, 5 is a spur, 6 is a paper feed roller, 7 is a paper discharge roller, 8 is a paper press roller, 9 is a drive pulley, and 10 is a tooth Belt 11, print medium guide 11, print medium entry side detection sensor 13, print medium exit side detection sensor 14, cap 14, tube pump 16, drive gear 16, driven gear 17

Claims (7)

  A plurality of inkjet heads are arranged along the conveyance direction of the print medium, and a cleaning unit for performing a recovery process of the inkjet head is arranged below each inkjet head, and printing is performed between adjacent inkjet heads. An ink jet printer characterized in that a transport roller is disposed below a medium transport path.   2. The ink jet printer according to claim 1, wherein a spur is disposed above the transport roller.   The ink jet printer according to claim 1, wherein a print medium guide is disposed between the cleaning unit and the transport roller and below the print medium transport path.   A print medium entry side detection sensor is disposed on the entry side of the most entrance ink jet head in the print medium conveyance direction, and after the passage of the print medium is detected by the print medium entry side detection sensor, the ink jet heads by the respective cleaning units The inkjet printer according to claim 1, wherein the recovery process is performed every predetermined time.   A print medium exit detection sensor is disposed on the exit side of the ink jet head that is the most exit side in the print medium transport direction, and the print medium exit side detection sensor detects a front end portion of the print medium in the transport direction and the print medium entrance side. The inkjet printer according to claim 4, wherein after the passage of the print medium is detected by a detection sensor, recovery processing of the inkjet head by each of the cleaning units is performed.   A paper feed roller is disposed on the input side in the print medium conveyance direction and a paper discharge roller is disposed on the output side in the print medium conveyance direction. The paper feed roller, paper discharge roller, and conveyance roller are connected by a single motor and a toothed belt. The inkjet printer according to claim 1, wherein the inkjet printer is driven.   A paper feed roller is provided on the input side in the print medium conveyance direction and a paper discharge roller is provided on the output side in the print medium conveyance direction, and the paper supply roller, paper discharge roller, and conveyance roller are driven by a single motor and gear. The ink jet printer according to claim 1, wherein the ink jet printer is provided.

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