Liquid jet device

Abstract

To inhibit occurrence of ozone when a medium is transported by utilizing electrostatic adsorption to an electrically charged conveyor belt in a liquid jet device.SOLUTION: A charged range of a conveyor belt which adsorbs a medium through electrostatic adsorption is selected from a plurality of predetermined ranges to be charged. The medium is adsorbed by the electrically charged conveyor belt and the conveyor belt is transported in a transport direction intersecting with a width direction of the medium. A liquid is jetted to a liquid jet head to the transported medium.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a liquid ejection apparatus. [Background technology]

[0002] A liquid ejection device ejects liquid toward a medium such as paper. In such a liquid ejection device, the medium may be transported, and in that case, electrostatic adsorption technology may be used. Patent Document 1 discloses a configuration in an image forming device in which a charging roller is brought into contact with a transport belt that transports print paper, and the transport belt is charged. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-27771 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a liquid injection device, when a medium is transported using electrostatic adsorption, a high voltage is applied to a charging roller to charge a conveyor belt in contact with the charging roller, and ozone may be generated by discharge due to the application of the high voltage. Ozone is used for sterilization and the like due to its high reactivity, but due to its high reactivity, there is a concern that it may cause deterioration of the parts constituting the device depending on the location of generation and the concentration. For example, when the conveyor belt of a liquid injection device is charged, the water-repellent film covering the nozzle surface of the liquid injection head may be deteriorated by the ozone generated at the charged part of the conveyor belt. Such a problem may not be overlooked when a medium smaller than the width of the conveyor belt is transported even though the entire surface of the conveyor belt is charged, that is, when a part of the charged conveyor belt is exposed. In any case, it is desirable to suppress the accidental generation of highly reactive ozone. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms or application examples.

[0006] One embodiment of the present disclosure is a liquid ejection apparatus comprising: a liquid ejection head that ejects liquid toward a medium; a conveyor belt that electrostatically attracts the medium and conveys the medium in a conveying direction intersecting with a width direction of the medium; and a charging unit that selects a charging range of the conveyor belt from a plurality of predetermined ranges and charges the conveyor belt. [Brief description of the drawings]

[0007] [Figure 1] 1 is a partial perspective view of a printing apparatus which is a liquid ejecting apparatus according to a first embodiment. [Diagram 2] FIG. 2 is an exploded perspective view of a head unit used in the printing apparatus. [Diagram 3] FIG. 2 is an explanatory diagram showing a part of the head unit in a cutaway view. [Figure 4] FIG. 1 is a schematic diagram of a printing apparatus. [Diagram 5] FIG. 2 is an explanatory diagram showing the configuration of a charging roller in a first embodiment in a plan view. [Figure 6] FIG. 4 is an explanatory diagram showing the connection relationship between a charging roller and a high voltage generator. [Figure 7] 4 is a flowchart showing a print processing routine in the printing device. [Figure 8] FIG. 11 is an explanatory diagram showing the configuration of a charging roller in a plan view according to a second embodiment. [Figure 9] FIG. 11 is an explanatory diagram showing the connection relationship between a charging roller and a high voltage generator in a second embodiment. [Figure 10] FIG. 11 is an explanatory diagram showing the configuration of a charging roller and a static electricity removal brush in a plan view according to a third embodiment. [Figure 11] FIG. 11 is an explanatory diagram showing the connection relationship between a charging roller and a static electricity removal brush in a third embodiment. [Figure 12] 13 is a flowchart showing a print processing routine in a third embodiment. [Figure 13] 11 is a flowchart showing an example of selection of a charging roller according to a paper width. [Figure 14] FIG. 11 is an explanatory diagram showing the relationship between the paper width and a threshold value when determining the charging range. [Figure 15] FIG. 11 is an explanatory diagram showing another example of the arrangement of the paper and the charging roller. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A. First embodiment: (A1)Hardware configuration: FIG. 1 is an explanatory diagram showing, in a perspective view, a partial configuration of an inkjet printing device 10 which is a first embodiment of a liquid ejection device. The printing device 10 corresponds to a "liquid ejection device." The printing device 10 of this embodiment handles printing paper S as a medium that receives the ejection of liquid, and ejects printing ink, which is an example of "liquid," onto the paper S to print desired characters and images. The printing device 10 includes a conveyor belt 45 for conveying the paper S, which is an example of a "medium," and the conveyor belt 45 is charged to electrostatically adsorb the paper S to the conveyor belt 45. The mechanism for conveying and charging the paper S will be described in detail later.

[0009] As shown in FIG. 1, the printing device 10 is a so-called line printer, and includes a device body 12, a head unit 30 constituting a line head, a conveying device 40 having a conveying belt 45 for conveying paper S, and a charging unit 50 for charging the conveying belt 45. The head unit 30 corresponds to a "liquid ejection head". The conveying device 40 includes two driving rollers 41 and 43, and the conveying belt 45, which is an endless belt, is stretched between the driving rollers 41 and 43. The conveying belt 45 has a charged film such as ETFE formed on the surface of polyimide or PET resin, and can be charged. In this embodiment, the medium to be conveyed by the conveying device 40 is paper medium paper S, but it is not limited to paper medium, and any medium can be treated as long as it is an object onto which ink is ejected and can be electrostatically attracted, such as synthetic resin sheets, fabrics, CDs, and DVDs. In the following embodiments, the liquid ejection device will be described as a printing device 10, but the liquid ejection device is not limited to the printing device 10 and may be any device that ejects liquid onto a medium transported by utilizing electrostatic adsorption.

[0010] In this embodiment, for convenience of explanation, each of the three-dimensional directions may be referred to with the symbols X, Y, and Z described below. For example, the direction in which the paper S is transported by the transport belt 45 is called the X direction. When it is necessary to distinguish between the forward direction and the reverse direction, the symbols "+" and "-" may be added, but the "+" symbol may be omitted. The width direction of the paper S, which is the right side of the transport direction X of the paper S, is called the Y direction (+Y direction), and the direction perpendicular to the X direction and Y direction and opposite to the direction of gravity is called the Z direction (+Z direction). When it is not necessary to distinguish between the forward direction and the reverse direction, the X direction may be simply called the transport direction of the paper, the Y direction may be called the width direction of the paper, and the Z direction may be called the up-down direction. These directions are also shown appropriately in other figures.

[0011] As shown in FIG. 1 and FIG. 2, the head unit 30 includes a plurality of ejection heads 100 and a head fixing substrate 200 that holds the plurality of ejection heads 100. The plurality of ejection heads 100 are arranged in parallel in the Y direction, which is the width direction of the paper S, and fixed to the head fixing substrate 200. A liquid storage unit such as an ink tank or ink cartridge (not shown) that stores ink is connected to the ejection head 100 so as to be able to supply ink. The liquid storage unit may be held, for example, on the ejection head 100, or may be held at a position different from the ejection head 100 of the device main body 12. In addition, a flow path or the like for supplying the ink supplied from the liquid storage unit to the ejection head 100 may be provided inside the head fixing substrate 200, or a flow path member may be provided on the head fixing substrate 200, and the ink from the liquid storage unit may be supplied to the head unit 30 via the flow path member. Of course, ink may be supplied directly from the liquid storage portion to the ejection head 100 without passing through the head fixing substrate 200 or a flow path member fixed to the head fixing substrate 200 .

[0012] The configuration of the ejection head 100 will be described with reference to FIG. 2 and FIG. 3. FIG. 2 shows one of the multiple ejection heads 100 as an exploded perspective view. FIG. 3 is an explanatory diagram showing a cross section of one of the ejection heads 100 provided in the head unit 30, partially cut away in the XZ plane. As shown in the figure, the ejection head 100 includes multiple head bodies 110 between a holder 120 and a cover 130. The head body 110 has a liquid ejection surface 20a on its lower surface (bottom surface in the -Z direction) on which nozzle openings are provided. A water-repellent film is formed on the liquid ejection surface 20a. The multiple head bodies 110 are arranged in the Y direction, and are stored and fixed between the holder 120 and the cover 130 in an assembled state.

[0013] The holder 120 is fixed to the head fixing substrate 200 in a state in which the head body 110 is stored. The holder 120 includes a holding portion 121 for holding the head body 110 and a foot portion 122 for engaging with the cover 130. The cover 130 is formed by bending a flat plate-shaped member, and includes a base portion 131 provided on the liquid ejection surface 20a side, and a bent portion 132 provided by bending both ends of the base portion 131 in the Y direction in the +Z direction. In this embodiment, since no bent portion is provided on both ends of the side in the X direction, the entire side portions of the base portion 131 in the Y direction can be the bent portion 132, and no edge portion exists. On the other hand, the entire side portions of both ends of the side in the X direction become the edge portion 133. The base portion 131 is bonded to the end faces of the foot portions 122 provided at the lower end of the holder 120 by an adhesive 141.

[0014] The base portion 131 is provided with an exposure opening 134 that is an opening for exposing the nozzle opening of each head body 110. In this embodiment, the exposure opening 134 is provided so as to open independently for each head body 110. That is, since the ejection head 100 of this embodiment has six head bodies 110, six independent exposure openings 134 are provided in the base portion 131. Of course, depending on the configuration of the head body 110, etc., one common opening may be provided for a head body group composed of a plurality of head bodies 110.

[0015] As described above, the ejection head 100 is fixed to the surface side of the head fixing substrate 200 that faces the paper S, i.e., the surface (lower surface) in the -Z direction. In this state, the lower surface of the cover 130 is located closest to the paper S in the ejection head 100. For this reason, a water-repellent film is formed on the lower surface 135 of the cover 130. The water-repellent film is provided to prevent satellites of ink droplets ejected from the nozzles of the head main body 110 from adhering to the surface, and to increase the durability of the ejection head 100.

[0016] In this embodiment, four ejection heads 100 are fixed to the head fixing substrate 200, but the number of ejection heads 100 is not particularly limited. In addition, the number of head bodies 110 provided on the ejection head 100 is not particularly limited to this.

[0017] (A2) Charging unit and its operation: The printing process in the printer 10 and the charging process of the conveyor belt 45 in the printing process will be described. As shown in FIG. 4, the printer 10 receives data from a computer (hereinafter abbreviated as PC) 15 and prints an image or the like on a sheet S. To perform this process, the printer 10 is provided with a control unit 70, a paper width sensor 71, a conveyor motor 75, a high voltage application unit 80, and the like. The control unit 70 receives image data from the PC 15, converts it into dot data that causes the head unit 30 to eject ink, and outputs it to the head unit 30. The control unit 70 also outputs a drive signal that drives the conveyor motor 75 to convey the sheet S by the conveyor belt 45. The conveyor motor 75 has a rotation shaft coupled to the rotation shaft of the drive roller 43, and by driving the conveyor motor 75, the drive roller 43 is rotated and the conveyor belt 45 that is stretched between the drive roller 41 and the conveyor motor 75 is driven.

[0018] The control unit 70 outputs a control signal to the high voltage application unit 80, and outputs a necessary high voltage to the charging unit 50, thereby charging the charging unit 50. The configuration of the charging unit 50 is shown in FIG. 5 and FIG. 6. FIG. 5 shows a main part of the printing device 10 in a plan view. As shown in the figure, the charging unit 50 includes a rotating shaft 60 made of an insulating material, for example, synthetic resin or ceramic, a charging roller 51 attached to the rotating shaft 60 at a position approximately at the center of the width direction of the conveyor belt 45, two charging rollers 52 provided on both sides of the charging roller 51, and two charging rollers 53 provided on the outside of the charging roller 51. The rotating shaft 60 functions as a common shaft member used as a common shaft for the three types of charging rollers 51 to 53. As an example of the length of the rotating shaft 60 in the axial direction (Y direction) of these charging rollers 51 to 53, the charging roller 51 is 110 mm, the charging roller 52 is 60 mm, and the charging roller 53 is 40 mm. In this way, the axial dimension of charging roller 51 is greater than the 105 mm width of the short side of A6 paper, the combined axial dimension of one charging roller 51 and two charging rollers 52 is greater than the 210 mm width of the short side of A4 paper, and the combined axial dimension of one charging roller 51, two charging rollers 52, and two charging rollers 53 is greater than the 297 mm width of the short side of A3 paper. All charging rollers 51 to 53 are made of rubber, and are insulated from each other by being spaced a short distance apart in the axial direction.

[0019] The charging unit 50 functions as a whole as a "charging section." Each of the charging rollers 51 to 53 charges a part of the width direction of the conveyor belt 45. Therefore, the configuration in which the charging roller 51 charges the corresponding "first range" of the conveyor belt 45 corresponds to the "first charging section," the configuration in which the charging roller 52 charges the corresponding "second range" of the conveyor belt 45 corresponds to the "second charging section," and the configuration in which the charging roller 53 charges the corresponding "third range" of the conveyor belt 45 corresponds to the "third charging section." Similarly, the charging rollers 51 to 53 correspond to the "first to third charging rollers."

[0020] Each of the charging rollers 51, 52, and 53 is not directly attached to an insulating rotating shaft 60, but is attached to the rotating shaft 60 via conductive charging shafts 61, 62, and 63 made of metal, as shown in FIG. 6. In other words, each of the charging shafts 61 to 63 and each of the charging rollers 51 to 53 are attached to the rotating shaft 60 with the same width and coaxially. Therefore, the charging shafts 61 to 63 are exposed on the end side of each of the charging rollers 51 to 53, and spring contact terminals 91 to 93 are in contact with these exposed shafts. As shown in FIG. 5, each of the contact terminals 91 to 93 is connected to contacts 81 to 83 connected to a high voltage application unit 80 provided in a high voltage generator 85 by electric wires L1 to L3. When the contacts 81 to 83 are turned on, that is, connected, by an instruction from the control unit 70, a high voltage of tens of thousands of volts output by the high voltage generator 85 is applied to the charging shafts 61 to 63 via the contact terminals 91 to 93. As a result, each of the charging rollers 51-53 attached coaxially to the charging shafts 61-63 is charged. Note that in this example, the high voltage output by one high voltage generator 85 is applied to each of the charging rollers 51-53 using the contacts 81-83, but a dedicated high voltage generator may be provided for each of the charging rollers 51-53. In this case, the application of the high voltage to the charging rollers 51-53 may be achieved by similarly turning on and off a setting, or may be achieved by directly controlling the operation of the high voltage generator corresponding to each of the charging rollers 51-53 by the control unit 70.

[0021] The outer circumference of each of the charging rollers 51-53 is in contact with the surface of the conveyor belt 45 at the driving roller 41. Therefore, when each of the charging rollers 51-53 is charged, the charge on the surface of each of the charging rollers 51-53 is transferred to the surface of the conveyor belt 45, and the conveyor belt 45 is also charged. As a result, when a sheet S is placed on the conveyor belt 45, the sheet S is electrostatically attracted to the conveyor belt 45. In FIG. 5, for ease of understanding, the correspondence between each of the charging rollers 51-53 and the sheet S is shown in a schematic manner. In the printing device 10 of this embodiment, the maximum width of the usable sheet S is about 310 mm, and A3 portrait printing is possible. At this time, the sheet S fits inside the width of the conveyor belt 45 charged by all of the charging rollers 51-53. Therefore, both ends of the A3 size sheet do not lift off the conveyor belt 45. On the other hand, the printer 10 is also capable of printing on narrow paper, such as an envelope E, and in this case, the width of the conveyor belt 45 charged by the charging roller 51 is slightly wider than the width of the envelope E, for example, 90 mm for a No. 4 long envelope. As shown in the figure, papers of different widths, such as the paper S and the envelope E, are aligned with respect to the conveyor belt 45 in the printer 10, with the center in the width direction being the reference position. This is true not only for the first embodiment, but also for the second and third embodiments.

[0022] 5 and 6, for convenience of illustration, the length of the conveyor belt 45 in the conveying direction (X direction) in the printing device 10, particularly the distance from the drive roller 41 to the head unit 30, is shortened, but in reality, the entire length (vertical length) of A3 size paper S is set to fit between the drive roller 41 and the head unit 30. Of course, the length of the conveyor belt 45 in the conveying direction may be longer or shorter than the maximum length of printable paper.

[0023] (A3) Printing process: With the device configuration of the printer 10 described above as a premise, the control unit 70 of the printer 10 performs the print process shown in Fig. 7. When the control unit 70 receives a signal to start printing from the PC 15, it starts the print process routine shown in the figure and first obtains the width of the paper (step S101). For example, the width of the paper is 297 mm for A3 paper S and 90 mm for a long No. 4 envelope. The paper width may be obtained from a printer driver running in the PC 15 during printing, or from a paper width sensor 71 provided in the printer 10.

[0024] Next, the size of the acquired paper is determined (step S111), and if it is determined that the size of the paper is A3, all of the contacts 81-83 are connected and a high voltage is applied to all of the charging rollers 51-53 (step S121), and if it is determined that the size of the paper is an envelope (long size No. 4), the contact 81 is connected and a high voltage is applied to the charging roller 51 (step S122). As a result, as described above, the range of the conveyor belt 45 that corresponds to the charged roller among the charging rollers 51-53 becomes chargeable.

[0025] Then, the conveying motor 75 is driven to rotate the driving roller 43, and the conveying belt 45 is moved to start the paper conveying process (step S131) ​​for conveying the paper. As the leading edge of the paper reaches the head unit 30 (step SRT), and until the trailing edge of the paper passes the head unit 30 (step STP), the image acquisition process (step S141) for acquiring image data from the PC 15 and the dot formation process (step S151) for forming dots corresponding to the image data on the paper are repeated. The image data may be gradation data in the Lab color system or CMYK color system that represents the image to be formed, or may be data that has been completely or partially halftoned, or compressed data obtained by compressing this data. Depending on the format of the acquired image data, the control unit 70 performs binarization or multi-value processing, and performs dot formation processing using the obtained dot data. If the acquired image data is in the form of dot data for each ink that can be formed by the head unit 30 from the beginning, the control unit 70 performs processing to rearrange the output timing of the dot data corresponding to interlacing, and outputs a dot formation signal to the ejection head 100. After that, an end process (step S161) is performed to end the print process routine. The end process includes processing such as ending charging the charging roller.

[0026] In the printing device 10, which is the first embodiment of the liquid ejection device described above, an image is formed on a medium, which is paper. At this time, the printing device 10 sets the width of the charge of the conveyor belt 45 according to the width of the medium, which is paper. Therefore, when printing on a narrow medium, such as an envelope E, the charging rollers 52 and 53 are not charged, so that no unnecessary power is consumed for charging. As a result, coupled with the fact that the range unnecessary for electrostatic adsorption of the paper on the conveyor belt 45 is not charged, the generation of ozone can be reduced. If a part of the surface of the conveyor belt 45 where the paper is not adsorbed is not charged, damage to the water-repellent film formed on the lower surface 135 of the cover 130 of the ejection head 100 and the liquid ejection surface 20a is also suppressed.

[0027] B. Second embodiment: Next, a printing apparatus 10B, which is a second embodiment of the liquid ejection apparatus, will be described. As shown in FIG. 8 and FIG. 9, the printing apparatus 10B of the second embodiment has the same configuration as the first embodiment, except for the configuration of the charging unit 50B. In the printing apparatus 10 of the first embodiment, the charging rollers 51 to 53 in the charging unit 50 are attached to one insulating rotating shaft 60 via the charging shafts 61 to 63, whereas in the printing apparatus 10B of the second embodiment, the charging rollers 51, 52, 53 in the charging unit 50B are directly attached to different rotating shafts 66, 67, 68, respectively. In addition, the rotating shafts 66 to 68 are all made of a conductive material, for example, metal, and are used as a conductive path for applying a high voltage to the charging rollers 51 to 53, instead of the electric wires L1 to L3 of the first embodiment. The charging rollers 51, 52, 53 are connected to a high voltage generator 85 from the rotating shafts 66, 67, 68 via contacts 81, 82, 83 of the high voltage application section 80.

[0028] In the charging unit 50B, one charging roller 51 attached to a rotating shaft 66, two charging rollers 52 attached to a rotating shaft 67, and two charging rollers 53 attached to a rotating shaft 68 are arranged at different positions so as to be in contact with the outer periphery of the conveyor belt 45 wound around the driving roller 41, as shown in Fig. 9. As shown in Fig. 8, the width direction range in which the five charging rollers 51, 52, and 53 charge the conveyor belt 45 is the same as in the first embodiment.

[0029] Therefore, it is possible to change the charging range of the conveyor belt 45 according to the difference in the width of the paper, as in the first embodiment, and in this respect as well, the printing device 10B of the second embodiment has the same effect as the printing device 10 of the first embodiment. Moreover, since the charging rollers 51, 52, and 53 are attached to different rotating shafts 66, 67, and 68, respectively, the charging shafts 61, 62, and 63 are not required, and therefore the contact terminals 91, 92, and 93 are also not required, and the configuration can be simplified. The application of a high voltage to the rotating shafts 66 to 68 can be easily achieved by a brush, a slip ring, or the like. In addition, in the second embodiment, the charging rollers 51 to 53 are configured to rotate integrally with the rotating shafts 66 to 68, respectively, but the shafts 66 to 68 may be fixed shafts, and the charging rollers 51 to 53 may rotate while contacting the shafts 66 to 68, respectively. In this way, the electrical connection to the shafts 66 to 68 becomes easier and more reliable.

[0030] In the second embodiment, as shown in FIG. 9, when viewed in the Y-axis direction, the charging roller 52 is arranged so as to overlap the adjacent charging rollers 51 and 53, but not overlap the rotation shafts 66 and 68. Therefore, the charging rollers 51 to 53 are arranged compactly without interfering with each other's rotation. If the charging rollers 51 to 53 are arranged so as not to overlap when viewed in the Y-axis direction, it is possible to provide an overlapping area between the charging area of ​​the conveyor belt 45 by the charging roller 51 and the charging area by the charging roller 52, or similarly, to provide an overlapping area between the charging area by the charging roller 52 and the charging area by the charging roller 53. In this way, it is easy to make the charging area in the width direction on the conveyor belt 45 by the two different charging rollers continuous.

[0031] In this embodiment, the positions in the X direction where the charging rollers 51, 52, and 53 contact the conveyor belt 45 are not the same but are shifted. When viewed along the direction in which the conveyor belt 45 moves due to the rotation of the driving rollers 41 and 43, the charging roller 53 contacts the conveyor belt 45 at the most upstream position, and the charging roller 51 contacts the conveyor belt 45 at the most downstream position. For this reason, taking into account the conveying speed of the conveyor belt 45, it is desirable to charge the charging roller 53 earlier than the charging roller 52 and charge the charging roller 51 at the most downstream position. In this way, it is possible to reduce the positional shift in the conveying direction of the charging range of the conveyor belt 45. If the conveying speed of the conveyor belt 45 is v [cm / s] and the shift in the conveying direction in which each charging roller contacts the conveyor belt 45 is ΔX [cm], the shift Δt [s] in the timing of starting charging is expressed as follows: Δt=ΔX / v The charging of the charging roller 52 may be started at a timing delayed by Δt from the start of charging of the charging roller 53, and the charging of the charging roller 51 may be started at a timing further delayed by Δt.

[0032] C. Third embodiment: Next, a printing apparatus 10C which is a third embodiment of the liquid ejection apparatus will be described. As shown in FIG. 10 and FIG. 11, the printing apparatus 10C of the third embodiment has the same configuration as the first embodiment, except for the configuration of the charging unit 50C. In the printing apparatus 10 of the first embodiment, the charging rollers 51 to 53 in the charging unit 50 are attached to one insulating rotating shaft 60 via the charging shafts 61 to 63, whereas in the printing apparatus 10C of the third embodiment, the charging rollers 51, 52, and 53 in the charging unit 50C are directly attached to a rotating shaft 69 made of a conductive material, for example, a metal. This rotating shaft 69 is used as a conductive path for applying a high voltage to the charging rollers 51 to 53. The charging rollers 51, 52, and 53 are connected to a high voltage generator 85 from the rotating shaft 69 via a contact 86 of a high voltage application section 80C.

[0033] In the printing apparatus 10C of the third embodiment, the charging unit 50C is provided with a mechanism for removing the charge once charged on the charging rollers 52 and 53. This is a first charge removing brush 97 and a second charge removing brush 98. The two first charge removing brushes 97 are provided so as to be in contact with the outer circumference of the two charging rollers 52, respectively, and the two second charge removing brushes 98 are provided so as to be in contact with the outer circumference of the two charging rollers 53, respectively. The first and second charge removing brushes 97 and 98 may be formed of conductive fibers such as carbon fibers or metal fibers, or may be configured by attaching conductive powder, such as carbon powder, to a synthetic resin brush and fixing it. Of course, the surface of the synthetic resin fiber may be coated with a conductive material and used to form the brush. The first and second charge removing brushes 97 and 98 are fixed to a mounting shaft 96 made of an insulating material, such as ceramic or synthetic resin.

[0034] The first and second charge-removing brushes 97 and 98 are connected to contacts 87 and 88 provided on the high-voltage application unit 80C via electric wires R1 and R2, respectively, and when the contacts 87 and 88 are in a connected state, they are connected to the ground line GND, which has a potential of 0. Therefore, when the contact 86 is connected and the charging rollers 51 to 53 are connected to the high-voltage generator 85 and charged, and then the contacts 87 and 88 are connected, the electric charge stored in the charging rollers 52 and 53 moves from the first charge-removing brush 97 and the second charge-removing brush 98 through the electric wires R1 and R2 to the ground line GND. As a result, the charge of the charging rollers 52 and 53 in contact with the first and second charge-removing brushes 97 and 98 connected to the connected contacts 87 and 88 is released.

[0035] FIG. 12 is a flowchart showing an outline of a print processing routine executed by the control unit 70 in the printer 10C of the third embodiment. This print processing executed by the control unit 70 is almost the same as the processing of the first embodiment, and is the same except for the processing after step S101 of the processing routine shown in FIG. 7 and immediately before step S131. In the third embodiment, the control unit 70 acquires the width of the paper (step S101), then connects the contact 86, applies a high voltage generated by the high voltage generator 85 to all of the charging rollers 51 to 53, and charges these rollers (step S105). Thereafter, the control unit 70 determines the paper size (step S111), and if it determines that the paper width is A3 size, it does nothing, and if it determines that the paper size is an envelope (long size No. 4), it connects the contacts 87 and 88 and grounds the first and second charge removing brushes 97 and 98 (step S125). The subsequent processing from step S131 onwards is the same as the first embodiment.

[0036] As a result, if the size of the paper to be printed is A3, the charging of the charging rollers 51 to 53 is maintained corresponding to the width of 297 mm, and approximately 320 mm in the width direction of the conveyor belt 45 is charged, and the A3 paper S is charged and adsorbed, and conveyed by the conveyor belt 45 to pass through the head unit 30, and printed by the head unit 30. On the other hand, if the paper to be printed is an envelope E with a width of approximately 90 mm, among the charging rollers 51 to 53, the charging rollers 52 and 53 are de-electrified, and the charging roller 51 charges approximately 110 mm in the width direction near the center of the conveyor belt 45, and the envelope E is charged and adsorbed near the center of the conveyor belt 45. The envelope E is conveyed by the movement of the conveyor belt 45 to pass through the head unit 30, and printed by the head unit 30.

[0037] Therefore, according to the printing device 10C of the third embodiment, as in the first and second embodiments, the charging range is set according to the width of the paper transported by the transport belt 45, so that the range unnecessary for electrostatic attraction of the paper to the transport belt 45 is not charged. This makes it possible to reduce the generation of ozone. If a part of the surface of the transport belt 45 where the paper is not attracted is not charged, damage to the water-repellent film formed on the lower surface 135 of the cover 130 of the ejection head 100 and the liquid ejection surface 20a is also suppressed.

[0038] In this embodiment, the static electricity of the once charged charging rollers 51 to 53 is removed by grounding the first and second static electricity removing brushes 97, 98 in contact with the charging rollers 52, 53, but the method of removing static electricity is not limited to this. For example, the initial positions of the first and second static electricity removing brushes 97, 98 may be set to positions spaced apart from the charging rollers 52, 53, and the actuator may be driven to move the first and second static electricity removing brushes 97, 98 to positions in contact with the charging rollers 52, 53. The static electricity removing brushes may be configured to contact the front or back surface of the conveyor belt 45 at positions corresponding to the charging rollers 52, 53.

[0039] D. Other embodiments: (1) Another embodiment of the present disclosure is a liquid ejection device. The liquid ejection device is characterized by including a liquid ejection head that ejects liquid toward a medium, a conveyor belt that electrostatically attracts the medium and conveys the medium in a conveying direction intersecting the width direction of the medium, and a charging unit that selects a charging range of the conveyor belt from a plurality of predetermined ranges and charges the conveyor belt. In this way, the charging range for electrostatically attracting the medium to the conveyor belt can be selected from a plurality of ranges, so that the charging range can be narrowed as necessary instead of always charging the widest range. This makes it possible to suppress ozone generation. In addition, if the charging range is selected based on whether or not to charge the medium, the power for charging the medium to be electrostatically attracted can be reduced. The charging unit is exemplified in the embodiment as charging units 50, 50B, 50C, 50D, etc., but is not limited to these forms. For example, the charging unit can be in contact with the conveyor belt and charge it, even if it is not a rotating member such as a charging roller. Generally, a non-rotating charging part can wear down through contact with the conveyor belt, making it difficult to maintain contact; however, by using a highly wear-resistant material such as ceramic for the part that comes into contact with the conveyor belt, or by using a spring or the like to push the contact member that makes up the conductive part towards the conveyor belt in proportion to the amount of wear, it is possible to configure a charging part at a practical level without using a charging roller.

[0040] Examples of liquid ejection devices include printing devices and coating devices. The device can reduce the generation of ozone in these devices and prevent damage to the devices caused by ozone. Inkjet printers that eject ink as a liquid sometimes form a water-repellent film on the underside of the printing head, but the device can prevent or avoid the damage to the water-repellent film caused by ozone.

[0041] There are various other possible configurations for the liquid ejection device. For example, there are devices that spray various dyes, pigments, paints, or other liquids to paint the transported medium, and devices that spray polishing or cleaning liquid onto the transported medium to polish or clean it. The medium can be anything that can be transported electrostatically, and can be paper, synthetic resin sheets, or the like. In some cases, thin plates such as ceramics can also be used.

[0042] (2) In the above configuration, the charging unit may select the charging range in the width direction so that at least a part of the range of the conveyor belt excluding the loading range where the medium is placed is charged to a smaller amount than the other ranges. This suppresses charging in the range of the conveyor belt excluding the loading range where the medium is placed, thereby reducing the charging range and suppressing the generation of ozone without affecting the electrostatic adsorption performance. The charging amount less than the other ranges may be set to 0, that is, no charging is performed.

[0043] (3) In the configurations of (1) and (2) above, the charging section may select the charging range of the conveyor belt when the conveyor belt conveys the medium based on the width dimension of the medium. In this way, the charging range of the conveyor belt is set based on the width dimension of the medium, so that it is easy to achieve both electrostatic adsorption of the medium in the conveyor belt and reliable conveyance of the medium and no unnecessary ozone generation. To set the charging range according to the width of the medium, a plurality of charging members such as charging rollers may be arranged in the width direction of the medium, and it may be determined which range of the members is to be used to charge the conveyor belt. Alternatively, the charging members may be made expandable in the width direction of the medium, and the length of the charging members in the width direction may be changed according to the width dimension of the medium. Such a structure can be easily realized, for example, by configuring the charging members to be slidable, and allowing at least a portion of the charging members to slide from a state in which the charging members completely overlap each other to a state in which the overlap between the charging members is reduced. Of course, the selection of the charging range may be set randomly, for example, without being based on the width dimension of the medium. Even in this case, when the width of the medium is narrow, the charging range may also be narrow, so that overall ozone generation can be suppressed compared to when the entire surface of the transport belt is charged.

[0044] (4) In the above configurations (1) to (3), the conveyor belt may include a first range and a second range different from the first range in the width direction, and the charging unit may include a first charging unit for charging the first range and a second charging unit for charging the second range, and may select a first charging mode in which the first charging unit charges the first range without charging the second range with the second charging unit, and a second charging mode in which the first and second charging units charge the first and second ranges, based on the dimension of the medium in the width direction. In this way, the charging range of the conveyor belt can be easily selected to one of the two ranges. Moreover, since the second charging mode includes the charging range in the first charging mode, it is easy to deal with the size of the medium in the width direction. It is also possible to charge independent ranges in the first charging mode and the second charging mode without providing a range that is commonly charged in the first charging mode and the second charging mode. For example, if the liquid ejection device is a printer, it is possible to perform printing by separately setting the charging range when transporting one medium I such as a narrow envelope and the charging range when transporting one medium B such as an envelope of a different width. In this case, it is also possible to provide a charging mode in which medium I and medium B are transported and printed separately, and a charging mode in which medium I and medium B are transported and printed simultaneously.

[0045] In the first to third embodiments, the first and second charging units correspond to a combination of charging roller 51 or charging roller 52 and high voltage application unit 80 that applies a high voltage to the charging roller. As already explained, the use of a charging roller is not essential in the first and second charging units. The same applies to the third charging unit described below.

[0046] (5) In the above configurations (1) to (4), the conveyor belt may include a third range in the width direction that is different from the first range and the second range, the second range being disposed between the first range and the third range, the charging unit may include a third charging unit for charging the third range, and the first charging mode and the second charging mode may each be selected from the first charging mode, the second charging mode, and a third charging mode in which the first to third ranges are charged by the first to third charging units without charging the third range by the third charging unit, based on the dimension of the medium in the width direction. In this way, the charging range of the conveyor belt can be easily selected to one of three ranges. Moreover, the second charging mode includes the charging range in the first charging mode, and the third charging mode includes the charging range in the second charging mode, so that it is possible to easily accommodate three stages of large and small dimensions of the medium in the width direction. As in the case of (5) above, the ranges charged in each charging mode may be set so that one charging mode includes the charging ranges in the other charging modes, or they may be independent, or the charging ranges in each charging mode may be set so that they partially overlap.

[0047] (6) In the configurations (1) to (5) above, the charging section may be configured to charge the second area by the second charging section when the ratio of the loading area of ​​the transport belt on which the medium is loaded to the second area in the width direction is greater than 0%, and not to charge the second area by the second charging section when the ratio of the loading area of ​​the transport belt to the second area in the width direction is 0% or less. In this way, the medium, including its widthwise ends, is electrostatically attracted to the transport roller.

[0048] The process of switching the charging mode will be described in detail below, taking the case of printing on a medium as an example. Fig. 13 is a flowchart showing the main part (steps S101 to S131) ​​of a print process routine that realizes a charging mode corresponding to the width of the printing paper, which is the medium, in the printing device, and Fig. 14 is an explanatory diagram showing the relationship between the width Pw of the paper PP and the first threshold value The and the second threshold value Ths when determining the charging range.

[0049] When the print process routine shown in FIG. 13 is started, first, the paper width Pw is obtained (step S101), and then it is determined whether or not this paper width Pw is larger than a first threshold value The (step S115). The first threshold value The is set to approximately the width of the charging roller 51, as illustrated in FIG. 14. The first threshold value The may be the distance of the gap between a pair of charging rollers 52 in the Y direction. In this embodiment, the width of the charging roller 51 is set to, for example, 110 mm, which is slightly larger than 90 mm, which is the width of an envelope E (long size No. 4). Of course, the width of the charging roller 51 corresponding to the first threshold value The may be set to a value slightly larger than the width of other papers.

[0050] If the paper width Pw used in the printing device is greater than the first threshold value The (step S115: "NO"), it is further determined whether the paper width Pw is greater than a second threshold value Ths (step S116). As illustrated in FIG. 14, the second threshold value Ths is set to a width including the two charging rollers 52 provided on both sides of the charging roller 51. The second threshold value Ths may be the distance between the pair of charging rollers 53 in the Y direction. By performing the two determinations in steps S115 and S116, the paper is classified into the following three types. [1] The width Pw of the paper is equal to or smaller than the first threshold value The (step S115: "NO"). [2] The width Pw of the paper is greater than the first threshold value The and is equal to or smaller than the second threshold value Ths (step S115: “YES” and step S116: “NO”). [3] The width Pw of the paper is greater than the second threshold value Ths (step S115: “YES” and step S116: “YES”).

[0051] In the case of [1], a high voltage is applied to the charging roller 51, and only the charging roller 51 is charged (step S127). In the case of [2], a high voltage is applied to the charging rollers 51 and 52, and the charging rollers 51 and 52 are charged (step S128). Furthermore, in the case of [3], a high voltage is applied to the charging rollers 51 to 53, and the charging rollers 51 to 53 are charged (step S129). The method of charging the charging rollers 51 to 53 as described above may be any of the methods of the first to third embodiments. Alternatively, another method may be used.

[0052] In this way, by comparing the paper width Pw with the first threshold value The and the second threshold value Ths corresponding to the width of the charging roller 51 alone or the width of the charging roller 51 and the charging roller 52 to set the range of the charging roller to be charged, the conveyor belt 45 is always charged over a range wider than the paper width Pw, and the paper can be electrostatically attracted. Both ends of the paper in the width direction tend to float up, but by doing this, the ends of the paper in the width direction are firmly electrostatically attracted to the conveyor belt 45. Therefore, even if the conveyor belt 45 conveys a medium such as paper at high speed, the entire paper is firmly attracted to the conveyor belt 45, and printing using ink droplets by the head unit 30 can be performed with high quality regardless of the location on the paper.

[0053] In the above example, the charging range of the conveyor belt 45 is set using three types of charging rollers, namely, charging rollers 51 to 53. However, a larger number of charging rollers may be used to set the charging range according to the paper width.

[0054] (7) In the above configurations (1) to (6), the charging unit may include a plurality of charging rollers for charging the conveyor belt, the charging rollers being in contact with at least two of the ranges dividing the conveyor belt in the width direction, and a voltage application unit for applying a charging voltage to each of the plurality of charging rollers individually. In this way, charging can be performed from the voltage application unit for each charging roller, the load for each voltage application unit can be leveled, and a sufficient charge can be applied to the divided range of the conveyor belt. In addition, by adopting such a configuration, it is also possible to change the voltage applied to each charging roller. Of course, as described in the first to third embodiments, it is also possible to distribute a high voltage from one high voltage generator to a plurality of charging rollers by contacts.

[0055] (8) In the above configurations (1) to (7), the multiple charging rollers may be fixed to an insulating common shaft member, and the voltage application unit may include a contact terminal that contacts an axial end face of the common shaft member of the charging rollers to apply the charging voltage to the multiple charging rollers individually. In this way, the contact terminal does not contact the surface of the charging roller, but contacts the axial end face. Since the outer periphery of the rotating charging roller has the fastest peripheral speed, if the charging roller is made of rubber or the like, It may be scraped off due to contact with the contact terminal. The axial end face moves at a slower speed than the charging roller, which reduces wear and tear and makes it easier to extend the life of the component.

[0056] (9) In the configurations (1) to (7) above, a first charging roller that is one of the plurality of charging rollers and a second charging roller different from the first charging roller may be arranged to contact the conveyor belt at different positions in the conveying direction of the conveyor belt, the first charging roller may be fixed to a conductive first shaft member, the second charging roller may be fixed to a conductive second shaft member different from the first shaft member, and the voltage application unit may apply the charging voltage to the first charging roller via the first shaft member and to the second charging roller via the second shaft member, respectively. In this way, since a plurality of charging rollers can be provided on different shaft members, it is possible to increase the degree of freedom in setting the charging range, for example by making it possible to make the charging ranges of adjacent charging rollers overlap in the width direction of the conveyor belt.

[0057] In this configuration, the position of the charging roller can be set independently of the other charging rollers. Compared to the above configuration using a common shaft member, it is easier to set the position of the charging roller and the charging range. On the other hand, the configuration using a common shaft member has the advantage that it is easier to make it smaller than a configuration using multiple shaft members.

[0058] (10) In the above configuration, a charge removing member may be provided that contacts some of the multiple charging rollers and reduces the charge on the contacting charging roller. This also makes it easy to set the charging range of the conveyor belt. In addition, if the charge removing member is in contact with the conveyor belt instead of the charging roller, a configuration can be adopted in which the entire width direction of the conveyor belt is charged at once, and the configuration can be simplified.

[0059] (11) In the configurations (1) to (10) above, the reference position of the medium in the width direction when the medium is transported by the transport belt may be set within the first range, and the length of the first charging section in the width direction may be greater than the length of the second charging section in the width direction. In this way, it is easy to set the range to be charged. The charging range may be changed according to the difference in the size of the medium by using the first charging section as a reference. This example is shown in FIG. 15. In the example shown in the figure, the charging unit 50D is composed of three charging rollers, and the reference position of the paper used for printing is one end of the charging unit 50D in the Y direction (the lower end in the figure). Of the three charging rollers constituting the charging unit 50D, the charging roller 51 has the same width as the charging roller 51 shown as the first to third embodiments, and the width of the second charging roller 54 adjacent to it in one direction is narrower than the width of the charging roller 51. The width of the second charging roller 54 is set to be approximately twice that of the charging roller 52. Furthermore, the third charging roller 56 adjacent to the second charging roller 54 in one direction has a width that is approximately twice that of the third charging roller 53. By setting it in this way, the paper width Pw can be compared with the first threshold value The and the second threshold value Ths by the process shown in FIG. 13, and the charging range can be easily set.

[0060] (15) In each of the above embodiments, a part of the configuration realized by hardware may be replaced by software. At least a part of the configuration realized by software may be realized by a discrete circuit configuration. In addition, when a part or all of the functions of the present disclosure are realized by software, the software (computer program) may be provided in a form stored in a computer-readable recording medium. The term "computer-readable recording medium" is not limited to portable recording media such as flexible disks and CD-ROMs, but also includes internal storage devices in a computer such as various RAMs and ROMs, and external storage devices fixed to a computer such as a hard disk. In other words, the term "computer-readable recording medium" has a broad meaning including any recording medium to which a data packet can be fixed, not temporarily.

[0061] The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention column can be appropriately replaced or combined in order to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if the technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0062] Reference Signs List 10, 10B, 10C...printing device, 12...device body, 20a...liquid ejection surface, 30...head unit, 40...transport device, 41...driving roller, 43...driving roller, 45...transport belt, 50, 50B, 50C, 50D...charging unit, 51...first charging roller, 52, 54...second charging roller, 53, 56...third charging roller, 60...rotating shaft, 61...charging shaft, 66-69...rotating shaft, 70...control unit, 71...paper width sensor, 75...transport motor , 80, 80C... high voltage application section, 81 to 83... contacts, 85... high voltage generator, 86 to 88... contacts, 91 to 93... contact terminals, 96... mounting shaft, 97... first charge removal brush, 98... second charge removal brush, 100... ejection head, 110... head body, 120... holder, 121... holding section, 122... foot section, 130... cover, 131... base section, 132... bending section, 133... edge section, 134... exposure opening, 135... underside, 141... adhesive, 200... head fixing substrate

Claims

1. A liquid ejection head that ejects liquid toward a medium; a conveyor belt that electrostatically attracts the medium and conveys the medium in a conveyance direction that intersects with the width direction of the medium; a charging section that selects a charging range of the conveyor belt from a plurality of predetermined ranges and charges the conveyor belt; A liquid ejection apparatus comprising:

2. The liquid ejection device according to claim 1, characterized in that, as one of the selections of the charging range in the width direction, the charging section charges at least a portion of the range of the conveying belt excluding the loading range on which the medium is placed to a smaller amount of charge than other ranges.

3. The liquid ejecting apparatus according to claim 1 , wherein the charging section selects a charging range of the transport belt when the medium is transported by the transport belt, based on a dimension of the medium in the width direction.

4. the conveyor belt includes, in the width direction, a first area and a second area different from the first area, The charging unit includes: a first charging section for charging the first area and a second charging section for charging the second area, selecting a first charging mode in which the second range is not charged by the second charging section and the first range is charged by the first charging section, and a second charging mode in which the first and second ranges are charged by the first and second charging sections, based on a dimension of the medium in the width direction; The liquid ejecting apparatus according to claim 3 .

5. the conveyor belt includes a third area in the width direction, the third area being different from the first area and the second area, the second range is disposed between the first range and the third range, The charging unit includes: a third charging section for charging the third area; In each of the first charging mode and the second charging mode, the third range is not charged by the third charging unit, selecting one of the first charging mode, the second charging mode, and a third charging mode in which the first to third ranges are charged by the first to third charging units based on a dimension of the medium in the width direction; The liquid ejecting apparatus according to claim 4 .

6. The charging unit includes: When a ratio of a placement area of ​​the conveyor belt on which the medium is placed to the second area in the width direction is greater than 0%, the second area is charged by the second charging unit; when a ratio of the placement range of the conveyor belt to the second range in the width direction is 0% or less, the second range is not charged by the second charging unit. The liquid ejecting apparatus according to claim 4 .

7. The charging unit includes: a plurality of charging rollers for charging the conveyor belt, the charging rollers being in contact with at least two of a plurality of ranges that divide the conveyor belt in a width direction; a voltage application unit that applies a charging voltage to each of the plurality of charging rollers; The liquid ejection apparatus according to claim 1 , further comprising:

8. The plurality of charging rollers are fixed to an insulating common shaft member, The liquid ejecting apparatus according to claim 7 , wherein the voltage application section includes a contact terminal that contacts an axial end face of the common shaft member of the charging rollers to apply the charging voltage to the plurality of charging rollers individually.

9. a first charging roller which is one of the plurality of charging rollers and a second charging roller which is different from the first charging roller are disposed so as to be in contact with the conveyor belt at different positions in the conveying direction of the conveyor belt; The first charging roller is fixed to a conductive first shaft member, the second charging roller is fixed to a second conductive shaft member different from the first shaft member, the voltage application unit applies the charging voltage to the first charging roller via the first shaft member and applies the charging voltage to the second charging roller via the second shaft member, respectively, individually. The liquid ejecting apparatus according to claim 7 .

10. 10. The liquid ejecting apparatus according to claim 7, further comprising a charge removing member that contacts some of the plurality of charging rollers and reduces electric charge on the charging rollers in contact with the charge removing member.

11. a reference position of the medium in the width direction when the medium is transported by the transport belt is set within the first range, The length of the first charging portion in the width direction is greater than the length of the second charging portion in the width direction. The liquid ejecting apparatus according to claim 4 .

Images