JP2015163445A - Liquid discharge device and liquid discharge method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge device which can suppress electrification of a medium.SOLUTION: A liquid discharge device comprises a transfer mechanism which transfers media S1, S2 in a transfer direction and a head which discharges liquid to the media, and makes the liquid discharged from the head reach the media. The liquid is electrified at the time of being discharged from the head. The transfer mechanism comprises a first transfer member 241 which is brought into contact with the media on the upper stream side in the transfer direction than the head and a second transfer member 242 which is brought into contact with the media on the upper stream side in the transfer direction than the head and is made of material different from the first transfer member. The first transfer member and the second transfer member are changed in accordance with the material of the media.

Description

  The present invention relates to a liquid ejection apparatus and a liquid ejection method.

  A liquid ejecting apparatus (for example, a printer) that includes a transport mechanism for transporting a medium (paper, cloth, OHP paper, etc.) in the transport direction and a head for ejecting liquid (for example, ink) to the medium, and ejects liquid from the head to the medium It has been known. In such a liquid ejecting apparatus, a droplet ejected from the head may have a charge (specifically, a positive charge). Further, the medium may be charged by friction with the transport mechanism or peeling (see, for example, Patent Document 1). When the medium is charged, the charged droplets become mist and adhere to the nozzle plate of the head. Therefore, in the printer of Patent Document 1, the charge on the medium is neutralized using a neutralizing brush.

JP 2004-66784 A

  However, when the charge of the medium is neutralized using the neutralization brush as described above, the neutralization brush may not be in contact with the entire surface of the medium. Therefore, there is a possibility that such a charge eliminating brush cannot completely remove charges.

  Accordingly, an object of the present invention is to suppress charging of a medium.

  A main invention for achieving the above object is a liquid ejection device comprising: a transport mechanism for transporting a medium in a transport direction; and a head for ejecting liquid onto the medium, and causing the liquid ejected from the head to land on the medium. In the apparatus, the liquid is charged when discharged from the head, and the transport mechanism includes a first transport member that contacts the medium upstream of the head in the transport direction, and the head A second transport member that is in contact with the medium upstream of the transport direction, the second transport member being different from the first transport member, and depending on the material of the medium The liquid ejection device is characterized in that the first transport member and the second transport member are changed.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

1 is a block diagram of the overall configuration of a printer. 2A and 2B are schematic diagrams illustrating the configuration of the printer 1. FIG. 2A is a side view showing a conveyance path, and FIG. 2B is a top view of a printing area. It is a flowchart for demonstrating printing operation. It is sectional drawing which shows the structure of medium S1 and medium S2 used by 1st Embodiment. It is a schematic explanatory drawing which shows the structure of the upstream platen 24 in 1st Embodiment. 6A and 6B are explanatory diagrams of the operation of the upstream platen 24 during printing. 7A and 7B are schematic explanatory views of the second embodiment. It is explanatory drawing which shows the structure of the conveyance member (roller) in 3rd Embodiment. 9A and 9B are schematic explanatory diagrams illustrating a switching operation in the third embodiment.

  At least the following matters will become clear from the description of the present specification and the accompanying drawings.

A liquid ejecting apparatus, comprising: a transport mechanism that transports a medium in a transport direction; and a head that discharges the liquid onto the medium, wherein the liquid ejected from the head is landed on the medium. The discharge mechanism is charged when discharged, and the transfer mechanism contacts the medium upstream of the head in the transfer direction and the medium upstream of the head in the transfer direction. A second conveying member that is in contact with the first conveying member, and the second conveying member is made of a different material from the first conveying member, and the first conveying member and the second conveying member are arranged according to the material of the medium. The liquid ejecting apparatus is characterized by being changed.
According to such a liquid ejecting apparatus, by changing the conveying member according to the material of the medium (using a conveying member having a small charge), frictional charging can be reduced and charging of the medium can be suppressed.

In such a liquid ejection apparatus, it is desirable to use the first transport member and the second transport member that have a charge train close to the charge train of the medium.
According to such a liquid ejecting apparatus, the charging of the medium can be reduced.

In this liquid ejection apparatus, it is preferable that at least one of the first transport member and the second transport member is conductive.
According to such a liquid ejecting apparatus, it is possible to more reliably suppress charging of the medium.

  In this liquid ejection apparatus, the first transport member and the second transport member may be platens. The first transport member and the second transport member may be rollers.

  Also, a liquid ejection method using a liquid ejection apparatus including a head for ejecting liquid onto a medium, wherein the medium is transported in a transport direction, and the material of the medium is upstream of the head in the transport direction. In response, the medium is brought into contact with the first transport member or a second transport member made of a material different from the first transport member, and the liquid charged from the head is discharged onto the medium. A liquid discharge method characterized by having

  In the following embodiments, an ink jet printer (referred to as printer 1) will be described as an example of the liquid ejection device. The printer 1 of the present embodiment is a large format printer (LFP) that handles a relatively large recording medium.

=== First Embodiment ===
<< Configuration example of printer 1 >>
First, a configuration example of the printer 1 will be described with reference to FIGS. 1, 2A, and 2B. FIG. 1 is a block diagram of the printer 1. 2A and 2B are schematic diagrams illustrating the configuration of the printer 1. 2A is a side view showing the conveyance path, and FIG. 2B is a top view of the printing area.
In the present embodiment, a description will be given using a long and roll-shaped medium (hereinafter referred to as medium S) as a medium on which the printer 1 records an image.

  The medium S used in the printer 1 is made of various papers such as plain paper, recycled paper, glossy paper, various fabrics, various non-woven fabrics, resin, metal, glass, resin film, and the like. In addition, as the resin of the resin film, PET (polyethylene terephthalate), PS (polyester), PP (polypropylene) and the like are also preferably used.

  As shown in FIG. 1, the printer 1 of the present embodiment includes a transport unit 20 as an example of a transport mechanism, a carriage unit 30, a head unit 40 for performing printing, a detector group 50, and a heater unit 70. And a controller 60 that controls these units and controls the operation of the printer 1.

  When the printer 1 receives print data from the computer 110 that is an external device, each unit can be controlled by the controller 60. That is, the controller 60 can print an image on the medium S by controlling each unit based on the print data received from the computer 110 (data relating to dots formed on the medium S). The situation in the printer 1 is monitored by the detector group 50, and the detector group 50 outputs the detection result to the controller 60. The controller 60 can control each unit based on the detection result output from the detector group 50.

  The transport unit 20 (corresponding to a transport mechanism) is for transporting the medium S in a predetermined direction (hereinafter referred to as a transport direction). As shown in FIG. 2, the transport unit 20 includes a feeding roller 21, a transport roller 22 a, a driven roller 22 b, a take-up roller 23, an upstream platen 24, a platen 25, and a downstream platen 26. .

  The feeding roller 21 has a winding shaft around which the medium S is wound and is rotatably supported. The feeding roller 21 is a roller for feeding the medium S from the winding shaft and feeding it to the upstream platen 24 side.

  The transport roller 22a is a roller that transports the medium S fed by the feed roller 21 along the transport direction, and is driven by a transport motor (PF motor) (not shown).

  The driven roller 22b is a roller that rotates as the transport roller 22a rotates. The driven roller 22b in the present embodiment is disposed so as to face the transport roller 22a with the medium S interposed therebetween. For this reason, the driven roller 22b rotates with the rotational drive of the conveyance roller 22a by the drive control of the controller 60. The transport amount of the medium S is adjusted by the rotation of the transport roller 22a and the driven roller 22b.

  The winding roller 23 is a roller for winding the medium S (printed roll paper) sent by the transport roller 22a, and is driven by a winding motor (not shown).

  The upstream platen 24, the platen 25, and the downstream platen 26 are provided on the transport path and support the medium S transported in the transport direction. The upstream platen 24 is provided upstream of the head 41 in the transport direction. The configuration of the upstream platen 24 of this embodiment will be described later. The platen 25 is provided in a region facing the head 41, and supports a portion of the medium S on the region during printing. The downstream platen 26 is provided downstream of the head in the transport direction.

  The carriage unit 30 is for moving the head 41 in a predetermined direction (a direction intersecting the transport direction; hereinafter referred to as a movement direction) during a printing operation. As shown in FIG. 2, the carriage unit 30 includes a carriage 31, a guide rail 32 extending in the moving direction, and a carriage motor (CR motor) (not shown).

  The carriage 31 can reciprocate in the movement direction along the guide rail 32 and is driven by a carriage motor (not shown). A head 41 is mounted on the carriage 31.

  The head unit 40 is for ejecting ink, which is an example of a liquid, onto a portion of the medium S that has been fed onto the upstream platen 24 by the transport unit 20. The head unit 40 has a head 41.

  The head 41 has a nozzle row composed of a plurality of nozzles for each color such as yellow (Y), magenta (M), cyan (C), and black (K) on the lower surface thereof.

  Each nozzle row is arranged in parallel with a space between each other along the moving direction (scanning direction) of the head 41. Each nozzle in each nozzle row is arranged linearly along the transport direction of the medium S. Each nozzle is provided with a piezo element (not shown) as a drive element for ejecting ink droplets. When a voltage having a predetermined time width is applied between the electrodes provided at both ends of the piezoelectric element, the piezoelectric element expands according to the voltage application time and deforms the side wall of the ink flow path. As a result, the volume of the ink flow path contracts according to the expansion and contraction of the piezo element, and ink corresponding to the contraction is ejected from each nozzle of each color as an ink droplet.

  In the present embodiment, solvent-based ink (Grecol-based ink) is used as ink ejected from the head 41. For example, when the solvent-based ink is landed on the medium S having an acrylic surface, the solvent dissolves and penetrates.

  Since the head 41 is provided on the carriage 31, when the carriage 31 moves in the movement direction, the head 41 also moves in the movement direction. Then, the head 41 is ejected intermittently while moving in the moving direction, whereby a dot line (raster line) in which dots are arranged along the moving direction is formed on the medium S. When printing is not performed, the head 41 (carriage 31) stands by at the home position HP shown in FIG.

  The heater unit 70 includes a pre-heater 74 that preheats the medium S upstream of the head 41, a heater 75 that heats the medium S at a position facing the head 41, and a medium downstream of the head 41 in the transport direction. And an after heater 76 for heating S. As shown in FIG. 2A, the pre-heater 74, the heater 75, and the after-heater 76 are provided at the same position in the transport direction as the upstream platen 24, the platen 25, and the downstream platen 26, respectively. In the present embodiment, the pre-heater 74 and the after-heater 74 are each provided on the back side of the medium S, but a heater may be provided above the print surface (front) side.

  The preheater 74 is for gradually raising the temperature of the medium S from room temperature toward a target temperature (for example, 40 degrees).

  The heater 75 is for maintaining the target temperature described above. As a result, when the ink has landed on the medium S, drying of the landed ink is promoted.

  Further, the after heater 76 raises the temperature of the medium S to a temperature higher than the target temperature (for example, 50 degrees), and quickly dries the ink that has landed on the medium S that has not yet been dried. In this way, at least before the ink is landed on the medium S, the ink that has landed on the medium S is completely dried and fixed.

  The detector group 50 monitors the situation in the printer 1. For example, the detector group 50 detects the amount of rotation of the transport roller 22 a and is used for control such as transport of the medium S. There are a medium detection sensor for detecting the presence or absence, a linear encoder for detecting the position of the carriage 31 (head 41) in the moving direction, and the like.

  The controller 60 is a control unit for controlling the printer 1. As shown in FIG. 1, the controller 60 includes an interface unit 61, a CPU 62, a memory 63, and a unit control circuit 64. The interface unit 61 is for transmitting and receiving data between the computer 110 which is an external device and the printer 1. The CPU 62 is an arithmetic processing unit for controlling the entire printer 1. The memory 63 is for securing an area for storing a program of the CPU 62, a work area, and the like. The CPU 62 controls each unit by a unit control circuit 64 according to a program stored in the memory 63.

≪About printing operation of printer 1≫
Next, a printing operation example of the printer 1 will be described with reference to FIG. FIG. 3 is a flowchart for explaining the printing operation.

  The controller 60 receives a print command from the computer 110 via the interface unit 61 (S001). This print command is included in the header of print data transmitted from the computer 110.

  Then, the controller 60 analyzes the contents of various commands included in the received print data, and performs the following processing using each unit.

First, the controller 60 performs a feeding process (S002).
The feeding process is a process of feeding (conveying) the medium S wound around the feeding roller 21 and positioning the medium S at a printing start position (also referred to as a cueing position). The controller 60 drives the transport motor, rotates the transport roller 22a to transport the medium S along the transport direction, and positions the medium S at the print start position.

Next, the controller 60 performs an ink ejection process (S003).
The ink ejection process is a process for forming dots on the medium S by intermittently ejecting ink from the head 41 moving in the moving direction. The controller 60 drives the carriage motor to move the carriage 31 located at the home position HP along the movement direction. Then, the controller 60 ejects ink from each nozzle of the head 41 based on the print data while the carriage 31 is moving. When ink droplets ejected from the head 41 land on the roll paper, dots are formed on the roll paper. This one-time ink discharge process is also called a pass.

After the ink ejection process, the controller 60 performs a transport process (S004).
The transport process is a process of moving the medium S relative to the head 41 along the transport direction. The controller 60 drives the transport motor and rotates the transport roller 22 to transport the medium S in the transport direction. By this carrying process, the head 41 can form dots at positions different from the positions of the dots formed by the previous ink discharge process.

Thereafter, the controller 60 determines whether or not to continue printing (S005).
If print data for printing on the medium S remains, the controller 60 determines to continue printing (NO in step S005), returns to step S103, and again executes the ink discharge process (pass) and the transport process. In this way, printing on the medium S is continued.
On the other hand, if there is no print data for printing on the medium S, the controller 60 determines that printing is finished (YES in step S005), moves the carriage 31 to the home position HP, and finishes the printing operation.

≪Problems caused by ink charging≫
In the printer 1 as in the present embodiment, the ink ejected from the head 41 may have a charge (specifically, a positive charge). This is due to charging due to flowing through the ink flow path from the ink cartridge to the head 41, charging generated when ejected from the head 41, charging due to passing through a filter (not shown) for removing ink impurities, and the like. It is. Further, as described above, in the present embodiment, solvent-based ink (Grecol-based ink) is used as ink ejected from the head 41. Solvent-based inks have a characteristic that they are more easily charged than water-based inks.

  Also, the medium S may be charged by friction with a transport member (for example, a platen or a roller) when transported, or may be charged (peeled) when it is separated from the transport member. Note that how the medium S is charged is determined by the charge train of the medium S and the transport member. Here, the electrification sequence is an order determined by whether to charge positively or negatively when different materials are rubbed. When frictional charging occurs between different materials, the positive side material is positively charged and the negative side material is negatively charged in the charge train.

  For example, when the medium S is acrylic and the conveying member is urethane, if they are separated after contacting, the negative urethane (conveying member) in the charging row of these two materials (urethane and acrylic) is negative (minus) The positive side acrylic (medium S) is positively (plus) charged.

  In the above case, the medium S is charged to the same polarity (plus) as the ink ejected from the head. In this case, the ink may become mist and adhere to the lower surface (nozzle plate) of the head 41.

  In addition, as a method of discharging the charge of the medium S, a contact-type discharging method (for example, discharging using a discharging brush) or a non-contact discharging method (for example, corona discharge) is known. In some cases, the electric charge may not be completely removed, and the electric charge may not be removed. In the case of the non-contact type, static electricity cannot be removed without a certain potential.

  Therefore, in this embodiment, charging of the medium S is suppressed without using the above-described static elimination method. More specifically, two types of platens of different materials are prepared as the upstream side platen 24 upstream of the head 41 in the transport direction, and the platen to be used is changed according to the material of the medium S.

≪About the medium≫
In the present embodiment, as the medium S, two mediums S having different materials (referred to as medium S1 and medium S2) are used.

FIG. 4 is a cross-sectional view showing the configuration of the medium S1 and the medium S2 used in the first embodiment.
The medium S1 has a front surface (printing surface) made of acrylic and a back surface made of PET. The medium S2 is made of acrylic on the front surface and PP on the back surface.

  When the ink (solvent ink) discharged from the head 41 lands on these surfaces (acrylic), the ink dissolves and penetrates the acrylic.

<< Configuration of Upstream Platen 24 of First Embodiment >>
FIG. 5 is a schematic explanatory view showing the configuration of the upstream platen 24 in the first embodiment.
The printer 1 according to the present embodiment includes a plurality of platen 241 (corresponding to the first transport member), platen 242 (corresponding to the second transport member), and a plurality of cams 243 as the upstream side platen 24.

  The platen 241 is a plate-like member formed of conductive PET, and the length of the platen 241 in the medium width direction (moving direction) is longer than the maximum width of the medium to be printed. In addition, electroconductive PET forms the conductive layer on the surface of a base material (PET base material). This conductive layer is formed by, for example, carbon content (surface only), metal vapor deposition, plating, or the like.

  The platen 242 is a plate-like member made of conductive PP and has the same shape as the platen 241. In addition, conductive PP also has a conductive layer formed on the surface of a base material (PP base material), similarly to conductive PET.

  The platen 241 and the platen 242 are arranged alternately (in a comb shape) along the transport direction so that the normal direction of the surface is parallel to the transport direction. Each of the platen 241 and the platen 242 is provided so as to be movable in the height direction (the vertical direction in the figure), and is urged toward the cam 243 side (the lower side in the figure) by a spring (not shown). The platen 241 and the platen 242 are each grounded.

  The cam 243 is provided for each combination of the platen 241 and the platen 242. The cam 243 is elliptical as shown in the figure, and the line connecting the centers of the cams 243 is parallel to the transport direction. Each cam 243 can be rotated clockwise and counterclockwise about the center of the ellipse. The platen in contact with the medium can be switched according to the rotation of the cam 243.

<< Operation during printing of upstream platen 24 >>
6A and 6B are explanatory diagrams of the operation of the upstream platen 24 during printing.
When the controller 60 determines that, for example, the type of medium input through the user interface (hereinafter also referred to as UI) is the medium S1 (back surface PET), the cam 243 rotates as shown in FIG. 6A. Let As a result, the platen 241 (conductive PET) is pushed up by the cam 243 and rises, and the platen 241 comes into contact with the medium S1. On the other hand, since the platen 242 is lowered, it does not come into contact with the medium S1. In this case, since the platen 241 is a material close to the back surface (PET) of the medium S1 and the charged column (both PET), charging due to friction or the like can be suppressed.

  If the controller 60 determines that the medium type is the medium S2 (back surface PP), the controller 243 rotates the cam 243 as shown in FIG. 6B. As a result, the platen 242 (conductive PP) is pushed by the cam 243 and rises to contact the medium S2. On the other hand, since the platen 241 is lowered, it does not come into contact with the medium S2. Also in this case, since the platen 242 is made of a material close to the back surface (PP) charge train (both PP) of the medium S2, charging due to friction or the like can be suppressed.

  As described above, in this embodiment, the upstream platen 24 on the upstream side in the transport direction with respect to the head 41 includes the conductive PET platen 241 and the conductive PP platen 242. When the medium to be printed is the medium S1 (back surface PET), the platen 241 is used, and when the medium is the medium S2 (back surface PP), the platen 242 is used.

  In this way, by switching the platen to be used according to the material of the medium S, it is possible to suppress the charging of the medium due to friction or peeling during conveyance.

  Although conductive PET and conductive PP are used as the platens 241 and 242, respectively, the present invention is not limited to this. A plurality of different materials may be prepared, and the one close to the charged column of the medium to be printed may be switched and used. By doing so, charging of the medium can be suppressed.

  In the above-described embodiment, the platens 241 and 242 are both conductive, but may not be conductive. Further, either one may be conductive. However, electrification can suppress charging more.

=== Second Embodiment ===
In the second embodiment, two platens are formed in advance so as to be replaceable as the upstream side platen 24, and the platen used (in contact with the medium) is replaced according to the medium. Since the configuration other than the upstream platen 24 is the same as that of the first embodiment, illustration and description thereof are omitted.

  7A and 7B are schematic explanatory views of the second embodiment. 7A and 7B are views seen from above the transport path.

  As shown in the drawing, in the second embodiment, a platen 24 a and a platen 24 b are provided as the upstream side platen 24. Further, the platen 24a is made of conductive PET like the platen 241 of the first embodiment, and the platen 24b is made of conductive PP like the platen 242 of the first embodiment. The platen 24a and the platen 24b of the second embodiment are in contact with the medium being transported on the surface. The platen 24a and the platen 24b are provided side by side in the moving direction (direction intersecting the transport direction). Further, the platen 24a and the platen 24b are provided so as to be movable in the moving direction while maintaining their positional relationship.

  Also in the second embodiment, the medium S1 (back surface PET) and the medium S2 (back surface PP) are used as the medium S as in the first embodiment.

  In the second embodiment, when the controller 60 determines that the type of the medium input through the user interface (UI) is the medium S1 (back surface is PET), for example, when performing printing, the platen 24a as illustrated in FIG. 7A. Is placed below the transport path. In this way, the platen 24a is brought into contact with the medium S1.

  Further, when the controller 60 determines that the medium type is the medium S2 (the back surface is PP), the controller 60 places the platen 24b below the transport path as shown in FIG. 7B. In this way, the platen 24b is brought into contact with the medium S2.

  Also in the case of the second embodiment, since the platen 24a and the platen 24b having a similar charge column are used for the medium S1 and the medium S2, charging can be suppressed.

=== Third Embodiment ===
In the third embodiment, two antistatic rollers made of different materials are prepared upstream of the head 41 in the conveying direction as the conveying member, and the roller to be used is switched according to the material of the medium. .

  FIG. 8 is an explanatory diagram illustrating a configuration of a conveyance member (roller) in the third embodiment. FIGS. 9A and 9B are schematic explanatory diagrams showing a switching operation in the third embodiment.

  In the third embodiment, two antistatic rollers (roller 291 and roller 292), a support shaft 293, and a shaft member 294 shown in FIG. 8 are arranged upstream of the head 41 in the transport direction (see FIGS. 9A and 9B). It has.

  The roller 291 is a urethane roller made of urethane. The roller 292 is a fluorine (Teflon (registered trademark)) roller. The roller 291 and the roller 292 have the same shape and are longer than the maximum width of the medium S to be printed. Note that the fluororesin (Teflon (registered trademark)) is on the negative side of urethane in the charging train. In other words, the fluororesin is more negatively charged than urethane.

  As shown in FIG. 8, the support shaft 293 is a shaft having a branch portion that rotatably supports the roller 291 and the roller 292. Further, both ends (both ends in the moving direction) of the support shaft 293 are rotatably attached to a frame (not shown) of the printer 1 or the like. The rotation of the support shaft 293 is controlled by the controller 60.

  With the above configuration, the controller 60 can switch the roller in contact with the medium S to either the roller 291 or the roller 292 as shown in FIGS. 9A and 9B by controlling the rotation of the support shaft 293.

  In the third embodiment, two antistatic rollers (roller 291 and roller 292) of different materials are provided as described above. The controller 60 selects a roller to be used according to the material of the medium S, and rotates the support shaft 293 to bring the selected roller into contact with the medium S. More specifically, the controller 60 makes the medium S contact the medium S and the roller of the roller 292 that is closer to the charged column.

  As described above, also in the third embodiment, charging of the medium S can be suppressed by switching the roller in contact with the medium S to either the roller 291 or the roller 292 according to the material of the medium S.

=== Other Embodiments ===
Although a printer or the like as one embodiment has been described, the above embodiment is for facilitating the understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About liquid ejection device>
In the above-described embodiment, an ink jet printer is described as an example of the liquid ejecting apparatus. However, the liquid ejecting apparatus is not limited to the ink jet printer, and ejects fluids other than ink (liquid, liquid material in which functional material particles are dispersed, fluid such as gel). It can also be embodied in a liquid ejection device. For example, color filter manufacturing apparatus, dyeing apparatus, fine processing apparatus, semiconductor manufacturing apparatus, surface processing apparatus, three-dimensional modeling machine, gas vaporizer, organic EL manufacturing apparatus (especially polymer EL manufacturing apparatus), display manufacturing apparatus, film formation You may apply the technique similar to the above-mentioned embodiment to the various apparatuses which applied inkjet technology, such as an apparatus and a DNA chip manufacturing apparatus.

  In addition, the printer of the above-described embodiment is a printer (so-called serial printer) that alternately repeats the conveyance operation and the dot formation operation, but is not limited thereto. For example, a printer (so-called line printer) in which a head (nozzle row) longer than the paper width is fixed on the transport path, and ink is intermittently ejected from the head while the medium is transported in the transport direction (so-called line printer). It may be. Also, a lateral printer may be used.

<About ink>
Since the above-described embodiment is an embodiment of a printer, ink is ejected from the nozzles, but the liquid ejected from the nozzles is not limited to ink. For example, liquids (including water) including metal materials, organic materials (especially polymer materials), magnetic materials, conductive materials, wiring materials, film-forming materials, electronic inks, processing liquids, gene solutions, etc. are ejected from nozzles. May be.

<Discharge method>
In the above-described embodiment, ink is ejected using a piezoelectric element (piezo element). However, the method of ejecting ink is not limited to this. For example, other methods such as a method of generating bubbles in the nozzle by heat may be used.

<About conveying members>
In the above-described embodiment, two types of platens (or rollers) are prepared as conveying members upstream of the head 41 in the conveying direction, and are switched according to the material of the medium. However, the present invention is not limited to this. For example, three or more types may be selected and used. Further, the switching method is not limited to the above-described embodiment, and may be switched by another method.

1 printer,
20 transport unit,
21 Feeding roller,
22a transport roller,
22b driven roller,
23 take-up roller 24 upstream platen,
25 platen,
26 downstream platen,
30 Carriage unit,
31 carriage,
32 guide rails,
40 head units,
41 heads,
50 detector groups,
60 controller,
61 Interface part,
62 CPU,
63 memory,
64 unit control circuit,
70 heater unit,
74 Preheater,
75 heaters,
76 After heater,
110 computers,
241 platen (conductive PET),
242 Platen (conductive PP)
243 cam,
24a platen (conductive PET),
24b platen (conductive PP),
291 rollers,
292 rollers,
293 spindle

Claims (6)

A transport mechanism for transporting the medium in the transport direction;
A head for discharging liquid onto the medium;
A liquid ejecting apparatus for landing the liquid ejected from the head on the medium,
The liquid is charged when discharged from the head,
The transport mechanism is
A first transport member that contacts the medium upstream of the head in the transport direction;
A second transport member that contacts the medium upstream of the head in the transport direction, the second transport member having a different material from the first transport member;
Have
The liquid ejecting apparatus according to claim 1, wherein the first transport member and the second transport member are changed according to a material of the medium. The liquid ejection device according to claim 1,
Among the first transport member and the second transport member, a liquid ejection apparatus using a charge train that is close to the charge train of the medium. The liquid ejection device according to claim 1 or 2,
At least one of the first transport member and the second transport member is conductive.
A liquid discharge apparatus characterized by that. The liquid ejection device according to any one of claims 1 to 3,
The liquid ejecting apparatus according to claim 1, wherein the first transport member and the second transport member are platens. The liquid ejection device according to any one of claims 1 to 3,
The liquid ejecting apparatus according to claim 1, wherein the first transport member and the second transport member are rollers. A liquid discharge method using a liquid discharge apparatus including a head for discharging liquid onto a medium,
Transporting the medium in a transport direction;
According to the material of the medium, upstream of the head in the transport direction, the medium is brought into contact with a first transport member or a second transport member having a different material from the first transport member;
Discharging the liquid charged from the head onto the medium;
A liquid discharge method comprising:

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