JP7124414B2 - Printer, controller, and method of printing - Google Patents

Description

The present invention relates to a printing device, a control device, and a printing method.

2. Description of the Related Art Conventionally, there has been known a printing apparatus that prints an image, characters, or the like on a medium by relatively moving a head having nozzles for ejecting liquid and a medium such as paper or cloth. Such a printing apparatus has a problem that part of the liquid ejected from the nozzles becomes atomized mist and scatters, contaminating the inside of the printing apparatus. For example, in Patent Document 1, an electrode is provided under an absorbing member that absorbs liquid (mist) that has not adhered to a material (medium) to be recorded, and a potential difference is generated between the electrode and a nozzle plate having openings (nozzles). A printing device is disclosed for generating and forming an electric field. According to this printing apparatus, it is described that the scattered mist can be attracted to the absorbing member by an electric field.

Japanese Patent Application Laid-Open No. 2008-62573

However, in the printing apparatus described in Patent Document 1, an absorbing member that absorbs mist is provided on the platen that supports the medium. The mist is attracted to the platen side, ie, the medium side, by an electric field generated between the electrode provided on the absorbing member and the nozzle plate. As a result, there is a risk that the medium will be contaminated with mist and that the print quality will be degraded.

A printing apparatus according to the present application is a printing apparatus that performs printing by ejecting liquid onto a medium, and includes a plurality of heads each having a conductive nozzle plate provided with nozzles; Among them, the nozzle plate of the head used for the printing is grounded, and the nozzle plate of the head not used for the printing is not grounded, and the control device controls the head and ejecting the liquid from.

In the printing apparatus described above, it is preferable that the nozzle plate is grounded via a switching unit that switches between a grounded state and a non-grounded state of the nozzle plate.

In the printing apparatus described above, it is preferable that the switching unit is a variable resistor whose resistance value can be changed electrically, and that the control device controls the variable resistor to change the resistance value.

In the printing apparatus described above, it is preferable that the head not used for printing is always a dummy head not used for printing.

In the printing apparatus described above, it is preferable that the dummy head ejects a cleaning liquid as the liquid from the nozzles.

The printing apparatus described above includes a conductive alignment plate that defines a mounting position of the head, the switching unit is provided on the alignment plate, and the nozzle plate is a conductive plate that covers at least a portion of the head. is preferably connected to the switching unit via the cover head and the alignment plate.

The control device of the present application controls a printing device having a plurality of heads each having a nozzle plate provided with nozzles, the nozzle plate being connected to the ground via a variable resistor whose resistance value can be changed electrically. a control device for changing the resistance value of the variable resistor connected to the nozzle plate of the head not used for printing to the variable resistor connected to the nozzle plate of the head used for printing It is characterized by performing control to make the resistance higher than the resistance value of the resistor and control to eject the liquid from the head before the printing.

A printing method of the present application is a printing apparatus having a plurality of heads each having a nozzle plate provided with nozzles, the nozzle plate being connected to the ground through a variable resistor whose resistance value can be changed electrically. The method, wherein the resistance value of the variable resistor connected to the nozzle plate of the head not used for printing is changed to the resistance value of the variable resistor connected to the nozzle plate of the head used for printing. and a flushing step of ejecting liquid from the head before printing.

1 is a schematic diagram showing a schematic overall configuration of a printing apparatus according to an embodiment; FIG. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1; FIG. 2 is a plan view showing a schematic configuration of a head unit; FIG. 2 is a schematic diagram showing a schematic configuration of a head; FIG. 2 is a cross-sectional view showing the internal configuration of the head; FIG. 2 is an electrical block diagram showing the electrical configuration of the printing apparatus; 4 is a flowchart for explaining a printing method of a printing device; The top view which shows schematic structure of the head unit which concerns on a modification. FIG. 2 is a schematic diagram showing a schematic configuration of a head used for printing; FIG. 4 is a schematic diagram showing a schematic configuration of a head that is not used for printing;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing below, the scale of each layer and each member is different from the actual scale in order to make each layer and each member recognizable.
1 to 3, 5 and 8, for convenience of explanation, X-axis, Y-axis and Z-axis are illustrated as three mutually orthogonal axes, and the tip side of the arrow indicating the axial direction is The “+ side” is defined as the “− side” and the base end side is defined as the “− side”. A direction parallel to the X-axis is called an “X-axis direction”, a direction parallel to the Y-axis is called a “Y-axis direction”, and a direction parallel to the Z-axis is called a “Z-axis direction”.

(embodiment)
<Configuration of printing device>
FIG. 1 is a schematic diagram showing a schematic overall configuration of a printing apparatus according to an embodiment. FIG. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is a plan view showing a schematic configuration of the head unit. First, a schematic configuration of a printing apparatus 100 according to this embodiment will be described with reference to FIGS. 1 to 3. FIG. In the present embodiment, an inkjet printing apparatus 100 that forms an image or the like on the medium 95 to perform textile printing on the medium 95 will be described as an example.

As shown in FIG. 1, the printing apparatus 100 includes a medium conveying section 20, a medium contact section 60, a printing section 40, a drying unit 27, a cleaning unit 50, a maintenance section 70, and the like. And it has the control device 1 which controls each of these parts. Each part of the printing device 100 is attached to the frame part 92 .

The medium conveying unit 20 conveys the medium 95 in the conveying direction (the +Y-axis direction in the printing unit 40). The medium conveying section 20 includes a medium supplying section 10 , conveying rollers 21 and 22 , a conveying belt 23 , a belt rotating roller 24 , a belt driving roller 25 , conveying rollers 26 and 28 , and a medium collecting section 30 . First, the transport path of the medium 95 from the medium supply section 10 to the medium recovery section 30 will be described. In this embodiment, the direction along the gravity is the Z axis, the direction in which the medium 95 is conveyed in the printing unit 40 is the Y axis, and the width direction of the medium 95 that intersects both the Z axis and the Y axis is the X axis. and

The medium supply section 10 supplies a medium 95 on which an image is to be formed to the printing section 40 side. As the medium 95, for example, natural fibers, cotton, silk, hemp, mohair, wool, cashmere, regenerated fibers, synthetic fibers, nylon, polyurethane, polyester, and woven or non-woven fabrics made of blends thereof can be used. . The woven fabric or non-woven fabric may be coated with a pretreatment agent for promoting color developability and fixability. The medium supply section 10 has a supply shaft section 11 and a bearing section 12 . The supply shaft portion 11 is formed in a cylindrical shape or columnar shape, and is provided so as to be rotatable in the circumferential direction. A belt-shaped medium 95 is wound around the supply shaft portion 11 in a roll shape. The supply shaft portion 11 is detachably attached to the bearing portion 12 . As a result, the medium 95 wound around the supply shaft portion 11 in advance can be attached to the bearing portion 12 together with the supply shaft portion 11 . Note that the winding direction of the medium 95 held by the supply shaft portion 11 is an example, and is not limited to this. A configuration in which the medium 95 is supplied from a roll with the recording surface wound inside may be used.

The bearing portion 12 rotatably supports both axial ends of the supply shaft portion 11 . The medium supply section 10 has a rotation drive section (not shown) that rotates the supply shaft section 11 . The rotary drive section rotates the supply shaft section 11 in the direction in which the medium 95 is delivered. The operation of the rotary drive section is controlled by the control device 1 . The transport rollers 21 and 22 relay the medium 95 from the medium supply section 10 to the transport belt 23 .

The transport belt 23 transports the medium 95 in the transport direction (+Y-axis direction). The conveying belt 23 is formed in an endless shape by connecting both ends of a belt-like belt, and is looped around a belt rotating roller 24 and a belt driving roller 25 . The conveying belt 23 is held under a predetermined tension so that the portion between the belt rotating roller 24 and the belt driving roller 25 is parallel to the floor surface 99 . An adhesive layer 29 for adhering the medium 95 is provided on the surface (support surface) 23 a of the transport belt 23 . The transport belt 23 supports (holds) the medium 95 supplied from the transport roller 22 and adhered to the adhesive layer 29 by the medium contact portion 60 to be described later. Thereby, a stretchable cloth or the like can be handled as the medium 95 .

The belt rotating roller 24 and the belt driving roller 25 support the inner peripheral surface 23 b of the conveying belt 23 . In addition, a configuration in which a support portion for supporting the transport belt 23 is provided between the belt rotating roller 24 and the belt driving roller 25 may be employed.

The belt drive roller 25 has a rotation drive section (not shown) that rotates the belt drive roller 25 . When the belt drive roller 25 is rotationally driven, the conveyor belt 23 rotates with the rotation of the belt drive roller 25 , and the rotation of the conveyor belt 23 causes the belt rotation roller 24 to rotate. By the rotation of the transport belt 23, the medium 95 supported by the transport belt 23 is transported in a predetermined +Y-axis direction (hereinafter also referred to as transport direction), and an image is formed on the medium 95 by the printing unit 40, which will be described later.

In this embodiment, the medium 95 is supported on the surface 23a of the transport belt 23 facing the printing unit 40 (+Z axis side), and the medium 95 moves along with the transport belt 23 from the belt rotating roller 24 side to the belt driving roller 25 side ( +Y-axis direction). Further, on the side (−Z axis side) where the surface 23a of the transport belt 23 faces the cleaning unit 50, only the transport belt 23 moves from the belt driving roller 25 side toward the belt rotation roller 24 side (−Y axis direction). . Although the conveying belt 23 has been described as having the adhesive layer 29 for adhering the medium 95, it is not limited to this. For example, the conveying belt may be an electrostatic attraction type conveying belt that attracts the medium to the belt with static electricity.

The transport roller 26 separates the image-formed medium 95 from the adhesive layer 29 of the transport belt 23 . The transport rollers 26 and 28 relay the medium 95 from the transport belt 23 to the medium recovery section 30 .

The medium collecting section 30 collects the medium 95 conveyed by the medium conveying section 20 . The medium collecting section 30 has a winding shaft section 31 and a bearing section 32 . The winding shaft portion 31 is formed in a cylindrical or columnar shape, and is provided so as to be rotatable in the circumferential direction. A belt-shaped medium 95 is wound around the winding shaft portion 31 in a roll shape. The winding shaft portion 31 is detachably attached to the bearing portion 32 . As a result, the medium 95 wound around the winding shaft portion 31 can be removed together with the winding shaft portion 31 .

The bearing portion 32 rotatably supports both axial ends of the winding shaft portion 31 . The medium recovery section 30 has a rotation drive section (not shown) that rotates the winding shaft section 31 . The rotation drive section rotates the winding shaft section 31 in the direction in which the medium 95 is wound. The operation of the rotary drive section is controlled by the control device 1 . Note that the winding direction of the medium 95 held in the medium collection unit 30 shown in FIG. 1 is an example, and is not limited to this. The recording surface of the medium 95 may be wound inside.

Next, each section provided along the medium conveying section 20 will be described.
The medium contact unit 60 is for bringing the medium 95 into close contact with the transport belt 23 . The medium contact section 60 is provided on the upstream side (−Y axis side) of the printing section 40 . The medium contact section 60 has a pressure roller 61 , a pressure roller drive section 62 and a roller support section 63 . The pressing roller 61 is formed in a cylindrical shape or columnar shape, and is provided so as to be rotatable in the circumferential direction. The pressing roller 61 is arranged so that the axial direction intersects the transport direction so as to rotate in the direction along the transport direction. The roller support portion 63 is provided on the inner peripheral surface 23b side of the transport belt 23 facing the pressure roller 61 with the transport belt 23 interposed therebetween.

The pressing roller drive unit 62 presses the pressing roller 61 in the conveying direction (+Y axis direction) and in the direction opposite to the conveying direction (−Y axis direction) while pressing the pressing roller 61 downward in the vertical direction (−Z axis side). Roller 61 is moved. The medium 95 superimposed on the conveying belt 23 is pressed against the conveying belt 23 between the pressing roller 61 and the roller support portion 63 . As a result, the medium 95 can be reliably adhered to the adhesive layer 29 provided on the surface 23 a of the conveying belt 23 , and floating of the medium 95 on the conveying belt 23 can be prevented.

The printing unit 40 is arranged above (on the +Z-axis side) the arrangement position of the conveying belt 23 and prints on the medium 95 placed on the surface 23 a of the conveying belt 23 . The printing unit 40 includes a carriage 43 on which the head unit 42 is mounted, a carriage moving unit 93 that moves the carriage 43 in the width direction (X-axis direction) of the medium 95 intersecting the transport direction, and the like. As shown in FIG. 3, the head unit 42 includes a plurality of heads 81-88 and a conductive alignment plate 48 that defines mounting positions of the heads 81-88. Each head 81 to 88 is exchangeably fixed to an alignment plate 48 supported by the carriage 43 .

Each of the heads 81 to 88 has, for example, a nozzle row in which 180 nozzles 41 arranged in the Y-axis direction are provided at a nozzle pitch of 180 dpi (dots per inch). For example, cyan (Cy), magenta (Ma), yellow (Ye), black (Bk), gray (Gy), blue (Bu), and red (Rd) are supplied from liquid tanks (not shown) to the heads 81-88. , orange (Or) liquid. Note that the number of heads, the number and nozzle pitch of the nozzles 41, and the types of ink are only examples, and the present invention is not limited to these. Further, in this embodiment, a configuration in which one nozzle row is provided in one head is shown, but a configuration in which one head is provided with a plurality of nozzle rows, or a configuration in which a plurality of heads form one nozzle row It may be configured to be

The carriage moving section 93 reciprocates the head unit 42 together with the carriage 43 along the X-axis direction (hereinafter also referred to as the main scanning direction). The carriage moving portion 93 is provided above the transport belt 23 (on the +Z-axis direction side) and has a pair of guide rails 93a and 93b extending along the X-axis direction. The guide rails 93 a and 93 b support the carriage 43 . The carriage 43 is guided along the X-axis direction by guide rails 93a and 93b, and is supported by the guide rails 93a and 93b so as to be reciprocally movable in the X-axis direction.

The carriage moving section 93 has a moving mechanism and a power source (not shown). As the movement mechanism, for example, a mechanism combining a ball screw and a ball nut, a linear guide mechanism, or the like can be employed. Further, the carriage moving section 93 is provided with a motor (not shown) as a power source for moving the carriage 43 along the X-axis direction. Various motors such as stepping motors, servo motors, and linear motors can be used as the motor. When the motor is driven under the control of the control device 1, the head unit 42 reciprocates along the X-axis direction together with the carriage 43. As shown in FIG.

The drying unit 27 is provided between the transport roller 26 and the transport roller 28 . The drying unit 27 dries the ink ejected onto the medium 95. The drying unit 27 includes, for example, an IR heater, and drives the IR heater to dry the ink ejected onto the medium 95. It can be dried in a short time. As a result, the belt-shaped medium 95 on which an image or the like is formed can be wound around the winding shaft portion 31 .

The cleaning unit 50 cleans the conveying belt 23 . The cleaning unit 50 is composed of a cleaning section 51 , a pressing section 52 and a moving section 53 . The moving part 53 can integrally move the cleaning unit 50 along the floor surface 99 and fix it at a predetermined position. The cleaning unit 50 is arranged between the belt rotating roller 24 and the belt driving roller 25 in the Y-axis direction.

The pressing part 52 is, for example, an elevating device composed of an air cylinder 56 and a ball bushing 57, and allows the cleaning part 51 provided thereon to be moved between a cleaning position and a retracted position. The cleaning position is a position where the cleaning roller 58 and the blade 55 contact the conveying belt 23 . The retracted position is a position where the cleaning roller 58 and the blade 55 are separated from the conveying belt 23 . At the cleaning position, the cleaning unit 51 cleans the surface (supporting surface) 23a of the conveying belt 23 from below (−Z-axis direction). Note that FIG. 1 shows a case where the cleaning unit 51 is raised and arranged at the cleaning position.

The cleaning section 51 has a cleaning tank 54 , a cleaning roller 58 and a blade 55 . The cleaning tank 54 is a tank that stores a cleaning liquid used for cleaning ink and foreign matter adhering to the surface 23 a of the conveying belt 23 . The cleaning roller 58 and the blade 55 are provided inside the cleaning tank 54 . As the cleaning liquid, for example, water or a water-soluble solvent (alcohol aqueous solution, etc.) can be used, and if necessary, a surfactant or an antifoaming agent may be added.

The lower side (−Z axis side) of the cleaning roller 58 is immersed in the cleaning liquid stored in the cleaning tank 54 . When the cleaning roller 58 rotates at the cleaning position, the cleaning liquid is supplied to the surface 23a of the transport belt 23, and the cleaning roller 58 and the transport belt 23 slide. As a result, ink adhering to the conveying belt 23 and fibers of the fabric as the medium 95 are removed by the cleaning roller 58 .

The blade 55 can be made of a flexible material such as silicone rubber, for example. The blade 55 is provided downstream of the cleaning roller 58 in the moving direction of the transport belt 23 . The cleaning liquid remaining on the surface 23 a of the transport belt 23 is removed by the sliding between the transport belt 23 and the blade 55 .

<Maintenance Department>
Returning to FIG. 2, the maintenance section 70 will be described. The printing apparatus 100 has a maintenance section 70 that performs maintenance on the heads 81-88. The maintenance unit 70 is provided on one side (the +X-axis direction side in this embodiment) of the transport belt 23 in the X-axis direction in which the head unit 42 reciprocates. The maintenance section 70 is provided at a position overlapping the head unit 42 that reciprocates in the X-axis direction in plan view from the +Z-axis direction. In this embodiment, the maintenance section 70 includes a suction section 72 that sucks the heads 81 to 88, a wiping section 73 that removes liquid, a flushing section 74 that discharges liquid from the nozzles 41 of the heads 81 to 88, and a cleaning section for the heads 81 to 88. It includes a cap portion 71 to prevent drying. Each maintenance section 70 is arranged in the order of a cap section 71, a suction section 72, a wiping section 73, and a flushing section 74 from the +X-axis direction end toward the -X-axis direction. The maintenance unit 70 includes an elevating device 76 composed of an air cylinder or the like, and is raised to a contact position where the heads 81 to 88 come into contact or a close proximity position when performing maintenance operations.

The cap unit 71 is a device that covers the heads 81-88. The ink ejected from the nozzles 41 provided in the heads 81 to 88 may have volatility. may become clogged. The cap portion 71 has a lid body 71a, and by covering the heads 81 to 88 with the lid body 71a, the nozzles 41 are prevented from being clogged.

The suction unit 72 is a device that covers each of the heads 81 to 88 and sucks the ink inside the heads 81 to 88 . The suction unit 72 includes a lid 72a and a negative pressure pump 72b. With the lid 72a covering the heads 81 to 88, the negative pressure pump 72b is driven to create a negative pressure in the lid 72a. Air bubbles, foreign matter, etc. in the heads 81-88 can be removed by the suction operation of sucking the ink inside the heads 81-88. As a result, it is possible to recover from or prevent ejection failures due to air bubbles or foreign matter. The printing apparatus 100 of this embodiment includes a suction unit 72 that covers each of the heads 81 to 88. may be configured to perform

The wiping part 73 is a device for wiping the nozzle plate 46 (see FIG. 3) on which the nozzles 41 are formed. The nozzle plate 46 is a member arranged on the surface of the heads 81 to 88 facing the medium 95 . If liquid or foreign matter adheres to the nozzle plate 46 , the droplets ejected from the nozzles 41 may land on the medium 95 at an unspecified location, resulting in an ejection failure. The wiping part 73 includes a blade 73a and a wiping motor (not shown) that moves the blade 73a along the Y-axis direction. The wiping portion 73 wipes away the liquid and foreign matter adhering to the nozzle plate 46 with the blade 73a, so that ejection failure can be recovered or prevented.

The flushing unit 74 is a device that catches droplets ejected from the nozzles 41 . The flushing section 74 includes a flushing box 74 a having porous fibers such as felt, and catches droplets ejected from the nozzles 41 . When the ink in the heads 81 to 88 is thickened or mixed with solid matter, droplets are ejected from the nozzles 41 to remove the thickened ink and solid matter, thereby adjusting the state of the ink. As a result, it is possible to recover from or prevent ejection failure due to thickened ink or solid matter.

FIG. 4 is a schematic diagram showing a schematic configuration of the head. Next, electrical connection of the nozzle plate 46 provided in the head 81 will be described with reference to FIG. The electrical connection of the nozzle plates 46 provided in the heads 82 to 88 is the same as that of the head 81, so the description thereof will be omitted.

The head 81 has a conductive nozzle plate 46 provided with nozzles 41 . The head 81 is connected to the nozzle plate 46 and has a cover head 47 that covers at least part of the head 81 . One end of the cover head 47 of this embodiment is connected to the end of the nozzle plate 46, and the other end rises vertically along the side wall of the head 81 and extends horizontally. The other horizontally extending end of the cover head 47 is joined to the alignment plate 48 with a nut or the like. The head 81 is thereby fixed to the alignment plate 48 .

The nozzle plate 46 is grounded via a switching portion 49 . The switching section 49 is provided on the alignment plate 48 corresponding to each of the heads 81 to 88 , and the nozzle plate 46 is connected to the switching section 49 via the cover head 47 . The nozzle plate 46, the cover head 47 and the alignment plate 48 are made of conductive material such as stainless steel. That is, one terminal of the switching portion 49 is electrically connected to the nozzle plate 46, and the other terminal is connected to the ground. Also, the switching section 49 is provided on the alignment plate 48 . Since the nozzle plate 46 is connected to the switching portion 49 via the cover head 47 and the alignment plate 48, electrical connection between the nozzle plate 46 and the switching portion 49 can be easily obtained when the head 81 is replaced. be able to.

The switching unit 49 switches the nozzle plate 46 connected as described above between a grounded state and a non-grounded state. Since the nozzle plate 46 of each head 81-88 is connected to the ground through the switching portion 49, the nozzle plate 46 of any head 81-88 can be changed from the grounded state to the non-grounded state, or from the non-grounded state to the grounded state. can be changed to The switching section 49 of the present embodiment is composed of a variable resistor whose resistance value is electrically variable (hereinafter, the switching section 49 is also referred to as the variable resistor 49). For example, variable resistor 49 may employ a digital potentiometer. The variable resistor 49 is preferably variable in the range of several Ω to several kΩ. Thereby, the control device 1 controls the variable resistor 49 to change the resistance value, thereby changing the nozzle plate 46 of any of the heads 81 to 88 from the grounded state to the non-grounded state or from the non-grounded state to the grounded state. can be easily switched.

FIG. 5 is a cross-sectional view showing the internal configuration of the head. Next, the configuration of the head 81 will be described with reference to FIG. Since the configuration of the heads 82 to 88 is the same as that of the head 81, the description thereof will be omitted.
As shown in FIG. 5, the head 81 includes a vibrator unit 140 in which a plurality of piezoelectric vibrators 147, a fixing plate 148, a flexible cable 144 and the like are unitized, and a case 141 capable of accommodating the vibrator unit 140. , and a channel unit 150 joined to the tip surface of the case 141 . The case 141 is a block-shaped member made of synthetic resin and has a storage space 145 with both open front and rear ends.

The piezoelectric vibrator 147 is formed in a comb shape elongated in the vertical direction. The piezoelectric vibrator 147 is a laminated piezoelectric vibrator configured by alternately laminating piezoelectric bodies and internal electrodes, and is capable of longitudinal vibration in the vertical direction (Z-axis direction) orthogonal to the lamination direction. mode piezoelectric vibrator. A tip end surface of each piezoelectric vibrator 147 is joined to the island portion 146 of the channel unit 150 . Note that this piezoelectric vibrator 147 behaves like a capacitor. That is, when the signal supply is stopped, the potential of the piezoelectric vibrator 147 is held at the potential immediately before the stop.

The channel unit 150 has the channel forming substrate 153 interposed therebetween, and the nozzle plate 46 is arranged on one surface side of the channel forming substrate 153 (− side in the Z-axis direction). is arranged on the other side (+side in the Z-axis direction) and laminated. The nozzle plate 46 is bonded to the flow path forming substrate 153 via an adhesive member. As the adhesive member, an epoxy adhesive, an acrylic adhesive, or the like can be used.

The nozzle plate 46 is made of thin stainless steel with a plurality of nozzles 41 formed along the Y-axis direction. The flow path forming substrate 153 is a plate-like member in which a series of ink flow paths including a common ink chamber 156, an ink supply port 157, a pressure chamber 158, and a nozzle communication port 159 are formed. In this embodiment, the channel forming substrate 153 is produced by etching a silicon wafer. The elastic plate 154 is a composite plate material having a double structure in which a resin film 151 is laminated on a support plate 152 made of stainless steel. forming.

In this head 81 , a series of ink flow paths from the common ink chamber 156 to the nozzle 41 through the pressure chamber 158 are formed for each nozzle 41 . By charging or discharging the piezoelectric vibrator 147, the piezoelectric vibrator 147 is deformed. That is, the piezoelectric vibrator 147 in this longitudinal vibration mode contracts in the longitudinal direction of the vibrator by charging and expands in the longitudinal direction of the vibrator by discharging. Therefore, when the potential is increased by charging, the island portion 146 is pulled toward the piezoelectric vibrator 147, the resin film 151 around the island portion 146 is deformed, and the pressure chamber 158 is expanded. Also, when the electric potential is lowered by the discharge, the pressure chamber 158 contracts.

In this way, the volume of the pressure chamber 158 can be controlled according to the potential, so that the pressure of the ink in the pressure chamber 158 can be changed, and the ink can be ejected from the nozzle 41 . For example, ink can be ejected in droplets by expanding the pressure chamber 158 having a constant volume (reference volume) and then rapidly contracting it.

In this embodiment, the configuration using the longitudinal vibration type piezoelectric vibrator 147 is exemplified, but the present invention is not limited to this. For example, a flexural deformation type piezoelectric vibrator in which a lower electrode, a piezoelectric layer, and an upper electrode are laminated may be used. As a means for expanding and contracting the pressure chamber 158, a so-called electrostatic actuator that generates static electricity between the diaphragm and the electrode, deforms the diaphragm by the electrostatic force, and discharges droplets from the nozzle 41, or the like. may be used. Further, the head may have a structure in which a heating element is used to generate bubbles in the nozzles, and the bubbles are used to eject ink as droplets.

<Electrical configuration>
FIG. 6 is an electrical block diagram showing the electrical configuration of the printing apparatus. Next, the electrical configuration of the printing device 100 will be described with reference to FIG.

The printing device 100 includes an input device 7 for inputting print information and the like, a control device 1 for controlling each section of the printing device 100 to print an image on a medium 95, and the like.
The input device 7 controls a print job or the like for causing the printing device 100 to print. The input device 7 includes printer driver software, and generates print data for causing the printing device 100 to print from input image data. As the input device 7, a desktop or laptop personal computer (PC), a tablet terminal, a portable terminal, or the like can be used. The input device 7 may be provided separately from the printing device 100 .

The control device 1 includes an interface section (I/F) 2, a CPU (Central Processing Unit) 3, a storage section 4, a control circuit 5, a drive signal generation section 6, and the like. The interface unit 2 is for transmitting and receiving data between the input device 7 handling input signals and images and the control device 1 . The CPU 3 is an arithmetic processing unit for processing input signals from various detector groups 8 and controlling the printing operation of the printing apparatus 100 .
The storage unit 4 is a storage medium for securing an area for storing programs of the CPU 3, a work area, and the like, and includes storage elements such as RAM (Random Access Memory) and EEPROM (Electrically Erasable Programmable Read Only Memory). there is
The drive signal generator 6 generates a drive signal for the piezoelectric vibrator 147 that causes the nozzles 41 of the heads 81 to 88 to eject liquid droplets.

The control device 1 controls ejection of liquid from the heads 81-88. More specifically, the control device 1 controls the driving of the piezoelectric vibrators 147 of the heads 81 to 88 based on the control signal output from the control circuit 5 and the drive signal output from the drive signal generator 6 to drive the piezoelectric vibrators 147 toward the medium 95 . Dispense the liquid.
The control device 1 controls the driving of the motor provided in the carriage moving section 93 according to the control signal output from the control circuit 5 to move the carriage 43 on which the head unit 42 is mounted in the width direction (X-axis direction) of the medium 95 . ).
The control device 1 controls the rotation drive units provided in each part of the medium conveying unit 20 according to the control signal output from the control circuit 5 to move the medium 95 placed on the conveying belt 23 in the conveying direction (Y-axis direction). + side).

The control device 1 cooperatively controls the carriage moving unit 93 and the heads 81 to 88, and main scanning (pass) moves the carriage 43 (head unit 42) in the width direction of the medium 95 while ejecting ink from the heads 81 to 88. ) and a sub-scan for controlling the medium conveying unit 20 to convey the medium 95 in the conveying direction are alternately repeated to form an image or the like on the medium 95 .
The control device 1 controls the variable resistors 49 corresponding to the heads 81 to 88 according to control signals output from the control circuit 5 to change resistance values.

FIG. 7 is a flowchart for explaining the printing method of the printing device. Next, a printing method of the printing apparatus 100 will be described with reference to FIG.

Step S1 is a print data generating step for generating print data.
Based on the image data, the input device 7 selects the head that uses the least amount of ink among the heads 81 to 88 as the head that is not used for printing. For example, the input device 7 sets the head 88 that ejects orange (Or) ink as a head that is not used for printing, and generates print data for printing using the remaining heads 81 to 87 . The control device 1 receives information such as print data from the input device 7 and stores it in the storage unit 4 .

In step S2, the controller 1 connects the resistance value of the variable resistor 49 connected to the nozzle plate 46 of the head 88 not used for printing to the nozzle plate 46 of the heads 81 to 87 used for printing. This is a resistance value varying step for controlling the resistance value to be higher than the resistance value of the variable resistor 49 . Based on the print data, the control device 1 controls the variable resistors 49 connected to the nozzle plates 46 of the heads 81 to 87 used for printing to have the lowest resistance value, and the head 88 not used for printing. The variable resistor 49 connected to the nozzle plate 46 is controlled to have the highest resistance value. As a result, the nozzle plates 46 of the heads 81 to 87 used for printing among the plurality of heads 81 to 88 are grounded, and the nozzle plate 46 of the head 88 not used for printing is not grounded.

Step S3 is a flushing step in which the controller 1 controls the ink to be ejected from the heads 81-88. The control device 1 controls flushing to eject ink from at least the head 88, which is not used for printing, among the heads 81 to 88, before executing printing to actually eject ink toward the medium 95.
When ink is ejected from the nozzles 41, the ink and the nozzle plate 46 are charged with different polarities due to friction between the nozzles 41 and the ink. For example, if the ink is negatively charged, the nozzle plate 46 will be positively charged. When flushing is performed, the nozzle plates 46 of the heads 81 to 87 used for printing and the nozzle plate 46 of the head 88 not used for printing are charged with a polarity different from that of the liquid. Since the nozzle plates 46 of the heads 81 to 87 used for printing are grounded, the generated charges are eliminated. Since the nozzle plate 46 of the head 88 that is not used for printing is not grounded, the generated charge is accumulated and the nozzle plate 46 is charged.

Step S4 is a sub-scanning step of moving the medium 95 in the transport direction. The control device 1 controls each section of the medium conveying section 20 and performs sub-scanning to move the medium 95 to a predetermined position in the conveying direction (+Y-axis direction) based on the print data.

Step S5 is a main scanning step of ejecting ink from the nozzles 41 of the heads 81-88. The control device 1 cooperatively controls the carriage moving portion 93 and the piezoelectric vibrators 147 of the heads 81 to 87 to move the carriage 43 (head unit 42) to the medium 95 while ejecting ink from the heads 81 to 87 toward the medium 95. Main scanning is performed by moving in the width direction. At this time, ink droplets and ink mist are ejected from the nozzles 41 of the heads 81 to 87 .

Since the mist has a very small mass compared to ink droplets, the kinetic energy given during ejection is rapidly lost due to the viscous resistance of the atmosphere, and the mist floats inside the printing apparatus 100 . Since the mist is charged with the same polarity as the ink, it is attracted to the nozzle plate 46 of the head 88 that is not used for printing and is charged to a polarity different from that of the ink. Since the head 88 not used for printing is positioned opposite the medium 95 , the mist travels in the direction opposite to the medium 95 . As a result, the mist floating in the printing apparatus 100 can be collected while suppressing contamination of the medium 95 with the mist.

Step S6 is a judgment step for judging whether or not maintenance of the heads 81-88 should be carried out. The control device 1 confirms whether the elapsed time since the start of printing or the previous maintenance has reached a predetermined time. If the predetermined time has elapsed (step S6: Yes), the process proceeds to step S7. If the predetermined time is not reached (step S6: No), the process proceeds to step S8.

Step S7 is a maintenance process for performing maintenance on the heads 81-88. The control device 1 controls the carriage moving portion 93 to move the heads 81 to 88 to be maintained to positions facing the wiping portion 73 . Then, the control device 1 controls the lifting device 76 and the wiping motor of the wiping unit 73 to cause the blade 73a to slide against the nozzle plate 46, thereby performing wiping for wiping ink adhering to the surface of the nozzle plate 46. . Further, the control device 1 moves the heads 81 to 88 to perform maintenance to positions facing the flushing section 74, and performs flushing by ejecting ink from the nozzles 41. FIG. By this maintenance process, the mist adhered to the nozzle plate 46 of the head 88 that is not used for printing is wiped off, and the nozzle plate 46 is recharged with an electric charge having a polarity different from that of the ink. As a result, the effect of collecting the mist is maintained.

Step S8 is a judgment step for judging whether or not to continue printing. The control device 1 refers to the print data stored in the storage unit 4 and confirms whether or not there is print data for the next line. If there is print data for the next line (step S8: Yes), return to step S4 and repeat steps S4 to S8. As a result, main scanning and sub-scanning are repeated, and an image or the like is printed on the medium 95 . If there is no print data for the next line (step S<b>8 : No), the control device 1 terminates the printing operation of the printing device 100 .

In this embodiment, a printing method is shown in which the heads 81 to 88 are maintained at the same time. may
Further, in this embodiment, the nozzle plate 46 and the switching section 49 are electrically connected via the cover head 47 and the alignment plate 48, but the nozzle plate 46 and the switching section 49 are The same effect can be obtained even with a configuration in which they are directly connected. Moreover, even if the nozzle plate 46 and the switching portion 49 are connected through one of the cover head 47 and the alignment plate 48, the same effect can be obtained.

As described above, according to the printing apparatus 100, the control apparatus 1, and the printing method according to this embodiment, the following effects can be obtained.
The printing apparatus 100 comprises a plurality of heads 81-88 having a conductive nozzle plate 46 with nozzles 41 provided thereon. Of the heads 81-88, the nozzle plates 46 of the heads 81-87 used for printing are grounded. Nozzle plates 46 of heads 88 not used for printing are not grounded. When ink is ejected from the nozzles 41, the ink and the nozzle plate 46 are charged with different polarities due to friction between the nozzles 41 and the ink. For example, if the ink is negatively charged, the nozzle plate 46 will be positively charged. When flushing is performed before printing on the medium 95, the nozzle plates 46 of the heads 81 to 87 used for printing and the nozzle plate 46 of the head 88 not used for printing are charged with a polarity different from that of the liquid. Occur. Since the nozzle plates 46 of the heads 81 to 87 used for printing are grounded, the generated charges are eliminated. Since the nozzle plate 46 of the head 88 that is not used for printing is not grounded, the generated charge is accumulated and the nozzle plate 46 is charged.

When the printing apparatus 100 starts printing on the medium 95 , ink droplets and ink mist are ejected from the nozzles 41 . Since the mist has a very small mass compared to ink droplets, the kinetic energy given during ejection is rapidly lost due to the viscous resistance of the atmosphere, and the mist floats inside the printing apparatus 100 . Since the mist is charged with the same polarity as the ink, it is attracted to the nozzle plate 46 of the head 88 that is not used for printing and is charged to a polarity different from that of the ink. Since the head 88 not used for printing is positioned opposite the medium 95 , the mist travels in the direction opposite to the medium 95 . Therefore, it is possible to provide the printing apparatus 100 that collects the mist floating in the printing apparatus 100 while preventing the medium 95 from being contaminated with the mist.

The nozzle plates 46 of the heads 81 to 88 are grounded via a switching portion 49 . The switching unit 49 switches between a grounded state and a non-grounded state of the nozzle plate 46 . As a result, the nozzle plate 46 of any of the heads 81 to 88 can be changed from the grounded state to the non-grounded state, or from the non-grounded state to the grounded state.

The switching unit 49 is composed of a variable resistor whose resistance value can be electrically varied. By controlling the resistance of the variable resistor 49 by the control device 1, the nozzle plate 46 of any of the heads 81 to 88 can be easily switched from the grounded state to the non-grounded state or from the non-grounded state to the grounded state.

The printing apparatus 100 includes a conductive alignment plate 48 that defines mounting positions of the heads 81-88. The switching section 49 is provided on the alignment plate 48 . The nozzle plate 46 is connected to the switching section 49 via the cover head 47 covering at least a part of each of the heads 81 to 88 and the alignment plate 48. Therefore, when the heads 81 to 88 are replaced, the nozzle plate 46 and the nozzle plate 46 are connected to each other. Electrical connection with the switching unit 49 can be easily obtained.

The control device 1 connects the resistance value of the variable resistor 49 connected to the nozzle plate 46 of the head 88 that is not used for printing among the heads 81 to 88 to the nozzle plate 46 of the heads 81 to 87 that are used for printing. control is performed to make the resistance value higher than the resistance value of the variable resistor 49 that is set. As a result, the control device 1 grounds the nozzle plates 46 of the heads 81 to 87 used for printing and ungrounds the nozzle plate 46 of the head 88 not used for printing. Then, the control device 1 controls ejection of ink from the heads 81 to 88 before printing on the medium 95 . When ink is ejected from the nozzles 41, the ink and the nozzle plate 46 are charged with different polarities due to friction between the nozzles 41 and the ink. For example, if the ink is negatively charged, the nozzle plate 46 will be positively charged. When flushing is performed before printing on the medium 95, the nozzle plates 46 of the heads 81 to 87 used for printing and the nozzle plate 46 of the head 88 not used for printing are charged with a polarity different from that of the liquid. Occur. Since the nozzle plates 46 of the heads 81 to 87 used for printing are grounded, the generated charges are eliminated. Since the nozzle plate 46 of the head 88 that is not used for printing is not grounded, the generated charge is accumulated and the nozzle plate 46 is charged.

When the control device 1 causes the printing device 100 to start printing on the medium 95 , the nozzles 41 eject ink droplets and ink mist. Since the mist has a very small mass compared to ink droplets, the kinetic energy given during ejection is rapidly lost due to the viscous resistance of the atmosphere, and the mist floats inside the printing apparatus 100 . Since the mist is charged with the same polarity as the ink, it is attracted to the nozzle plate 46 of the head 88 that is not used for printing and is charged to a polarity different from that of the ink. Since the head 88 not used for printing is positioned opposite the medium 95 , the mist travels in the direction opposite to the medium 95 . Therefore, it is possible to provide the control device 1 that collects the mist floating in the printing device 100 while suppressing the contamination of the medium 95 with the mist.

In the printing method of the printing apparatus 100, the resistance value of the variable resistor 49 connected to the nozzle plate 46 of the head 88 not used for printing is connected to the nozzle plates 46 of the heads 81 to 87 used for printing. It includes a resistance value varying process for controlling the resistance value to be higher than the resistance value of the variable resistor 49 and a flushing process for controlling the ejection of ink from the heads 81 to 88 .
In the variable resistance process, the control device 1 grounds the nozzle plates 46 of the heads 81 to 87 used for printing, and ungrounds the nozzle plate 46 of the head 88 not used for printing. In the flushing process, the control device 1 controls ejection of ink from the heads 81 to 88 before printing onto the medium 95 . When ink is ejected from the nozzles 41, the ink and the nozzle plate 46 are charged with different polarities due to friction between the nozzles 41 and the ink. For example, if the ink is negatively charged, the nozzle plate 46 will be positively charged. When flushing is performed before printing on the medium 95, the nozzle plates 46 of the heads 81 to 87 used for printing and the nozzle plate 46 of the head 88 not used for printing are charged with a polarity different from that of the liquid. Occur. Since the nozzle plates 46 of the heads 81 to 87 used for printing are grounded, the generated charges are eliminated. Since the nozzle plate 46 of the head 88 that is not used for printing is not grounded, the generated charge is accumulated and the nozzle plate 46 is charged.

When printing on the medium 95 is started, the nozzles 41 eject ink droplets and ink mist. Since the mist has a very small mass compared to ink droplets, the kinetic energy given during ejection is rapidly lost due to the viscous resistance of the atmosphere, and the mist floats inside the printing apparatus 100 . Since the mist is charged with the same polarity as the ink, it is attracted to the nozzle plate 46 of the head 88 that is not used for printing and is charged to a polarity different from that of the ink. Since the head 88 not used for printing is positioned opposite the medium 95 , the mist travels in the direction opposite to the medium 95 . Therefore, it is possible to provide a printing method that collects the mist floating in the printing apparatus 100 while preventing the medium 95 from being contaminated with the mist.

The present invention is not limited to the above embodiments, and various modifications can be made to the above without departing from the spirit of the present invention. Modifications are described below.

FIG. 8 is a plan view showing a schematic configuration of a head unit according to a modification. FIG. 9 is a schematic diagram showing a schematic configuration of a head used for printing. FIG. 10 is a schematic diagram showing a schematic configuration of a head that is not used for printing. Next, the configuration of the head unit 142 according to the modification will be described with reference to FIGS. 8 to 10. FIG. In addition, the same numbers are attached to the same components as in the embodiment, and redundant explanations are omitted.

As shown in FIG. 8, the head unit 142 includes heads 182 to 185 used for printing and heads 181 and 186 not used for printing. The heads 181 and 186 that are not used for printing are dummy heads that are always not used for printing (hereinafter the heads 181 and 186 are also referred to as dummy heads 181 and 186). Each head 181 to 186 is exchangeably supported by the carriage 143 . Each of the heads 181 to 186 has, for example, a nozzle row in which 180 nozzles 41 arranged in the Y-axis direction are provided at a nozzle pitch of 180 dpi (dots per inch). For example, cyan (Cy), magenta (Ma), yellow (Ye), and black (Bk) inks are supplied to the heads 182 to 185 from liquid tanks (not shown). Also, the dummy heads 181 and 186 are supplied with cleaning liquid (W) as a liquid from a liquid tank (not shown).

As shown in FIGS. 9 and 10, the heads 181-186 have a nozzle plate 46 and a cover head 47 connected to the nozzle plate 46. As shown in FIG. The heads 182-185 used for printing are grounded through the cover head 47. FIG. That is, heads 182-185 are grounded. Dummy heads 181 and 186 that are not used for printing are ungrounded.

The control device 1 ejects the cleaning liquid from the dummy heads 181 and 186 before performing printing in which ink is ejected toward the medium 95 . For example, when the cleaning liquid is negatively charged, the nozzle plates 46 of the dummy heads 181 and 186 are charged with positive charges, and the nozzle plates 46 are charged.

When the controller 1 performs main scanning, the mist discharged from the nozzles 41 of the heads 182 to 185 is negatively charged, and is attracted to the nozzle plates 46 of the dummy heads 181 and 186 . In the main scanning direction, the dummy heads 181 and 186 are provided on both sides of the heads 182 to 185 capable of preferably absorbing mist. As a result, the mist ejected from the nozzles 41 of the heads 182 to 185 while moving in the main scanning direction is preferably attracted to the nozzle plate 46 of the dummy head 181 or dummy head 186 that passes immediately after.

When the control device 1 performs maintenance at a predetermined time during printing, cleaning liquid is discharged from the nozzles 41 of the dummy heads 181 and 186 by flushing. As a result, the mist adhered to the dummy heads 181 and 186 is preferably washed away.

In this modified example, the heads 182 to 185 are fixed in the grounded state and the dummy heads 181 and 186 are fixed in the non-grounded state. A configuration in which the heads 181 and 186 are not grounded via the switching portion 49 may be employed.

The contents derived from the embodiment are described below.

A printing apparatus according to the present application is a printing apparatus that performs printing by ejecting liquid onto a medium, and includes a plurality of heads each having a conductive nozzle plate provided with nozzles; Among them, the nozzle plate of the head used for the printing is grounded, and the nozzle plate of the head not used for the printing is not grounded, and the control device controls the head and ejecting the liquid from.

According to this configuration, the nozzle plate of the head used for printing is grounded. Nozzle plates of heads not used for printing are not grounded. When the liquid is ejected from the nozzle, the liquid and the nozzle plate are charged with different polarities due to the friction between the nozzle and the liquid. For example, if the liquid is negatively charged, the nozzle plate will be positively charged. When the control device ejects the liquid from the head before printing on the medium, the nozzle plate of the head used for printing and the nozzle plate of the head not used for printing are charged with a polarity different from that of the liquid. . Since the nozzle plate of the head used for printing is grounded, the generated charges are eliminated. Since the nozzle plate of the head that is not used for printing is not grounded, the charge generated on the nozzle plate side is accumulated and the nozzle plate becomes charged.

When the printing apparatus starts printing on a medium, liquid droplets and liquid atomized mist are ejected from the nozzles. Since the mist has a very small mass compared to liquid droplets, the kinetic energy given during ejection is rapidly lost due to the viscous resistance of the atmosphere, and the mist floats inside the printing device. Since the mist is charged with the same polarity as the liquid, it is attracted to the nozzle plate of the head not used for printing, which is charged with a polarity different from that of the liquid. Since the heads not used for printing are positioned facing the medium, the mist travels in the opposite direction to the medium. Therefore, it is possible to provide a printing apparatus that collects the mist floating in the printing apparatus while suppressing contamination of the medium with the mist.

In the printing apparatus described above, it is preferable that the nozzle plate is grounded via a switching unit that switches between a grounded state and a non-grounded state of the nozzle plate.

According to this configuration, since the nozzle plate of each head is connected to the ground through the switching unit, the nozzle plate of any head can be changed from the grounded state to the non-grounded state or from the non-grounded state to the grounded state. be able to.

In the printing apparatus described above, it is preferable that the switching unit is a variable resistor whose resistance value can be changed electrically, and that the control device controls the variable resistor to change the resistance value.

According to this configuration, the nozzle plate of each head is grounded via a variable resistor whose resistance value can be changed electrically, so that the nozzle plate of any head can be changed from the grounded state to the non-grounded state, Alternatively, it can be electrically controlled from a non-grounded state to a grounded state.

In the printing apparatus described above, it is preferable that the heads not used for printing are always dummy heads not used for printing.

According to this configuration, since the printing apparatus always has a dummy head that is not used for printing, the dummy head can be arranged at a position where the mist can be preferably absorbed.

In the printing apparatus described above, it is preferable that the dummy head ejects a cleaning liquid as the liquid from the nozzles.

According to this configuration, the dummy head ejects the cleaning liquid, so that the mist adsorbed to the nozzle plate of the dummy head can be washed away favorably.

The printing apparatus described above includes a conductive alignment plate that defines a mounting position of the head, the switching unit is provided on the alignment plate, and the nozzle plate is a conductive plate that covers at least a portion of the head. is preferably connected to the switching unit via the cover head and the alignment plate.

According to this configuration, the printing apparatus includes an alignment plate that defines the mounting position of the head when replacing the head. The switching section is provided on the alignment plate. Since the nozzle plate is connected to the switching section via the cover head covering at least a part of the head and the alignment plate, electrical connection between the nozzle plate and the switching section is easily obtained when the head is replaced. be able to.

The control device of the present application controls a printing device having a plurality of heads each having a nozzle plate provided with nozzles, the nozzle plate being connected to the ground via a variable resistor whose resistance value can be changed electrically. wherein the resistance value of a variable resistor connected to the nozzle plate of the head not used for printing is set to the resistance value of the variable resistor connected to the nozzle plate of the head used for printing. and control to discharge the liquid from the head before the printing.

According to this control device, the control device changes the resistance value of the variable resistor connected to the nozzle plate of the head not used for printing to the resistance value of the variable resistor connected to the nozzle plate of the head used for printing. Control to make it higher than the resistance value. As a result, the control device grounds the nozzle plates of the heads used for printing and ungrounds the nozzle plates of the heads not used for printing. Then, the control device controls ejection of the liquid from the head before printing on the medium. Friction between the nozzle and the liquid as the liquid is ejected from the nozzle causes the liquid and the nozzle plate to be charged with different polarities. For example, if the liquid is negatively charged, the nozzle plate will be positively charged. When the control device ejects the liquid from the head before printing on the medium, the nozzle plate of the head used for printing and the nozzle plate of the head not used for printing are charged with a polarity different from that of the liquid. . Since the nozzle plate of the head used for printing is grounded, the generated charges are eliminated. Since the nozzle plate of the head that is not used for printing is not grounded, the charge generated on the nozzle plate side is accumulated and the nozzle plate becomes charged.

When the control device causes the printing device to start printing on the medium, liquid droplets and atomized liquid mist are ejected from the nozzles. Since the mist has a very small mass compared to liquid droplets, the kinetic energy given during ejection is rapidly lost due to the viscous resistance of the atmosphere, and the mist floats inside the printing device. Since the mist is charged with the same polarity as the liquid, it is attracted to the nozzle plate of the head not used for printing, which is charged with a polarity different from that of the liquid. Since the heads not used for printing are positioned facing the medium, the mist travels in the opposite direction to the medium. Therefore, it is possible to provide a control device that collects the mist floating in the printing apparatus while suppressing contamination of the medium with the mist.

A printing method of the present application is a printing apparatus having a plurality of heads each having a nozzle plate provided with nozzles, the nozzle plate being connected to the ground through a variable resistor whose resistance value can be changed electrically. The method, wherein the resistance value of the variable resistor connected to the nozzle plate of the head not used for printing is changed to the resistance value of the variable resistor connected to the nozzle plate of the head used for printing. and a flushing step of ejecting liquid from the head before printing.

According to this printing method, in the resistance value varying step, the resistance value of the variable resistor connected to the nozzle plate of the head not used for printing is changed to the variable resistor connected to the nozzle plate of the head used for printing. higher than the resistance of the device. As a result, the nozzle plate of the head used for printing can be grounded, and the nozzle plate of the head not used for printing can be ungrounded. Then, in the flushing process, the liquid is ejected from the head before printing on the medium. Friction between the nozzle and the liquid as the liquid is ejected from the nozzle causes the liquid and the nozzle plate to be charged with different polarities. For example, if the liquid is negatively charged, the nozzle plate will be positively charged. When the liquid is ejected from the head in the flushing process before printing on the medium, the nozzle plate of the head used for printing and the nozzle plate of the head not used for printing are charged with a polarity different from that of the liquid. . Since the nozzle plate of the head used for printing is grounded, the generated charges are eliminated. Since the nozzle plate of the head that is not used for printing is not grounded, the charge generated on the nozzle plate side is accumulated and the nozzle plate becomes charged.

When printing on a medium is started, liquid droplets and liquid atomized mist are ejected from the nozzles. Since the mist has a very small mass compared to liquid droplets, the kinetic energy given during ejection is rapidly lost due to the viscous resistance of the atmosphere, and the mist floats inside the printing device. Since the mist is charged with the same polarity as the liquid, it is attracted to the nozzle plate of the head not used for printing, which is charged with a polarity different from that of the liquid. Since the heads not used for printing are positioned facing the medium, the mist travels in the opposite direction to the medium. Therefore, it is possible to provide a printing method that collects the mist floating in the printing apparatus while suppressing contamination of the medium with the mist.

DESCRIPTION OF SYMBOLS 1... Control apparatus, 2... Interface part, 3... CPU, 4... Storage part, 5... Control circuit, 6... Drive signal generation part, 7... Input device, 8... Detector group, 10... Medium supply part, 20... MEDIUM CONVEYING UNIT 27 DRYING UNIT 30 MEDIUM RECOVERING UNIT 40 PRINTING UNIT 41 NOZZLE 42, 142 HEAD UNIT 43, 143 CARRIAGE 46 NOZZLE PLATE 47 COVER HEAD 48 ALIGNMENT Plate 49 Switching unit Variable resistor 50 Cleaning unit 60 Medium contact unit 70 Maintenance unit 71 Cap unit 72 Suction unit 73 Wiping unit 74 Flushing unit 81 to 88 , 182 to 185... Head 93... Carriage moving unit 95... Medium 100... Printing device 140... Vibrator unit 181, 186... Head, dummy head.

Claims (9)

A printing device that prints by ejecting liquid onto a medium,
a plurality of heads having a conductive nozzle plate with nozzles;
a controller;
Among the plurality of heads,
the nozzle plate of the head used for the printing is grounded;
the nozzle plate of the head that is not used for the printing is non-grounded;
The control device controls, before the printing, the nozzles of the head used for the printing , and
, ejecting the liquid from the nozzles of the head that are not used for the printing ;
A printing device characterized by: The nozzle plate is connected to the ground via a switching unit that switches between a grounded state and a non-grounded state of the nozzle plate.
2. The printing apparatus according to claim 1, wherein: A printing device that prints by ejecting liquid onto a medium,
a plurality of heads having a conductive nozzle plate with nozzles;
a controller;
Among the plurality of heads,
the nozzle plate of the head used for the printing is grounded;
the nozzle plate of the head not used for the printing is non-grounded;
The control device ejects the liquid from the head before the printing,
The nozzle plate is switched between a grounded state and a non-grounded state.
connected to the ground through a switching unit that
A printing device characterized by: The switching unit is a variable resistor whose resistance value can be changed electrically,
The control device controls the variable resistor to change the resistance value.
4. The printing apparatus according to claim 2 or 3 , characterized in that: the head not used for the printing is always a dummy head not used for the printing;
5. The printing apparatus according to any one of claims 1 to 4 , characterized in that: the dummy head ejects a cleaning liquid as the liquid from the nozzle;
6. The printing apparatus according to claim 5 , wherein: A conductive alignment plate that defines the mounting position of the head,
The switching unit is installed on the alignment plate,
The nozzle plate is connected to the switching unit via a conductive cover head covering at least a portion of the head and the alignment plate.
6. The printing apparatus according to any one of claims 2 to 5 , characterized in that: A control device for controlling a printing device comprising a plurality of heads each having a nozzle plate provided with nozzles, wherein the nozzle plate is connected to the ground via a variable resistor whose resistance value can be changed electrically. ,
The resistance value of the variable resistor connected to the nozzle plate of the head not used for printing is set higher than the resistance value of the variable resistor connected to the nozzle plate of the head used for printing. Elevation control and
Control for ejecting liquid from the head before the printing;
A control device characterized by performing A printing method for a printing apparatus comprising a plurality of heads each having a nozzle plate provided with nozzles, the nozzle plate being grounded via a variable resistor whose resistance value can be changed electrically, comprising:
The resistance value of the variable resistor connected to the nozzle plate of the head not used for printing is set higher than the resistance value of the variable resistor connected to the nozzle plate of the head used for printing. a step of increasing the resistance value;
a flushing step of ejecting liquid from the head before the printing;
A printing method comprising:

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