JP5641196B2 - Liquid ejector - Google Patents

Description

  The present invention relates to a liquid ejecting apparatus represented by a facsimile or a printer.

  Hereinafter, an ink jet printer as an example of the liquid ejecting apparatus will be described as an example. The ink jet printer has a support member (also referred to as a platen) at a position facing the ink jet recording head, and is configured to define the distance between the ink jet recording head and the recording paper by supporting the recording paper with the support member. ing.

  Here, in recent inkjet printers, ink droplets have been miniaturized with the aim of further improving the recording quality. For example, ink droplets have been miniaturized to about several pl. For this reason, the mass of the ink droplets is extremely small, and even when the ink droplets are ejected from the ink jet recording head onto the recording paper, some of the ink droplets do not land on the recording paper and float as mist, causing various problems. . In addition, in so-called borderless recording, in which recording is performed without margins on the four sides of the recording paper, ink droplets are also ejected to areas outside the end of the recording paper, so the above-described mist floating phenomenon becomes even more pronounced. .

  Therefore, conventionally, as shown in Patent Documents 1 and 2, a potential difference is provided between the ink jet recording head, the recording paper, and the support member, and by generating an electric field, a Coulomb force is applied to the ink droplet to record the ink droplet. Techniques for attracting paper have been proposed.

JP 2007-118321 A JP 2007-118318 A

<< 1. Issues arising with high-speed conveyance of recording paper >>
By the way, recent inkjet printers have been proposed that use a fixed inkjet recording head that does not scan (move), that is, a so-called line head, and that can perform recording with extremely high throughput. In such an ink jet printer, the recording paper is conveyed at a very high speed along a paper conveyance path inside the apparatus.

  However, it has been found that the following problems occur with such high-speed conveyance of recording paper. That is, paper dust generated at the time of cutting adheres to the end (edge) of the recording paper, but these three elements of the recording paper, the support member (platen), and the ink jet recording head (hereinafter referred to as “recording section configuration”). When the electric potential between the elements is not controlled, paper dust attached to the recording paper flies toward the ink jet recording head due to the electric field generated between the recording unit components. In particular, when recording paper is transported at a high speed, vibrations and impacts during the transport of the paper are increased, and paper powder flying is thus more noticeable.

  In addition, friction between the recording paper stored in the paper cassette and frictional charging and peeling due to sliding contact / contact between the components of the paper transport path (for example, edge guides, transport rollers, etc.) and the recording paper. Charging becomes significant, that is, the recording unit component is more significantly charged. As a result, the electric field formed between the recording unit components becomes stronger, and the charging of the paper dust itself becomes stronger, so the Coulomb force applied to the paper dust becomes larger and the paper dust adheres more to the ink jet recording head. It becomes prominent.

  In addition, even when the paper dust itself is not charged, if the flying paper dust is placed in an electric field, the paper dust is biased by dielectric polarization or electrostatic induction, which causes the inkjet It will be attracted to the recording head.

  FIG. 11 is an explanatory diagram for showing this problem. Reference numeral 160 denotes an ink jet recording head, reference numeral 160a denotes a nozzle plate, reference numeral 170 denotes a support member (platen), and reference numeral 170a denotes a rib formed on the support member 170. ing. Reference sign P indicates a recording sheet, reference sign Pe indicates a paper end, and reference sign d indicates paper dust. Further, “+” and “−” circled indicate the charging polarity.

  The recording paper P is neutralized by a static elimination brush or the like, and therefore the paper powder d adhering to the recording paper P is not charged. However, as shown in the enlarged view of the paper dust d, when the nozzle plate 160a is positively charged and the support member 170 is negatively charged (an example), the dielectric polarization (the paper dust d has the property of a dielectric). A negative charge appears on the nozzle plate side of the paper powder d, and a positive charge appears on the support member side due to electrostatic induction (when the paper powder d has the property of a conductor). . As a result, the paper powder d is attracted to either side of the nozzle plate 160a and the support member 170.

  When the paper dust adheres to the ink jet recording head, the paper dust directly closes the nozzle opening, or the paper dust moves to the nozzle opening at the time of cleaning (wiping) the nozzle surface, thereby causing missing dots. .

  In addition to the paper dust physically blocking the nozzle opening in this way, the filler such as calcium carbonate that constitutes the paper powder reacts with the moisture of the ink to increase the viscosity, thereby inhibiting the meniscus vibration of the nozzle opening. In some cases, ink droplet ejection may be hindered. Therefore, preventing paper dust from adhering to the ink jet recording head is extremely important for obtaining an appropriate recording quality in the ink jet printer.

<< 2. Problems of conventional technology >>
In Patent Documents 1 and 2 described above, as described above, a potential difference is provided between the ink jet recording head, the recording paper, and the support member (recording unit component), and a coulomb force is applied to the ink droplets by generating an electric field. A technique for attracting ink droplets to recording paper has been proposed. Therefore, if paper dust is regarded as being in the same row as the ink droplets, it seems that the paper dust can be prevented from adhering to the ink jet recording head by attracting the paper dust to the recording paper side by controlling the electric field.

  However, the cellulose fibers and fillers that make up the paper powder are easily charged to either positive or negative polarity in the charge column, and therefore, by forming an electric field in a specific direction between the recording unit components, the ink jet recording head side is formed. Even if it is attempted to prevent the paper powder from flying, it is not possible to prevent the paper powder charged to the opposite polarity from flying to the ink jet recording head side.

  In JP 2003-165230 A, an air duct is provided around the nozzle plate for the purpose of preventing adhesion of paper dust, dust and the like to the periphery of the nozzle portion of the ink jet recording head. A recording device is described that is sometimes configured to inject humid air from an air duct. However, in such a configuration, the complexity of the configuration leads to an increase in the size and cost of the apparatus, and there is a possibility that paper dust adheres to the recording head due to the airflow.

  Japanese Patent Application Laid-Open No. 2008-213255 describes a technique for collecting paper dust by a paper dust collecting member having charging properties. However, in the present technology, paper dust cannot always be efficiently collected due to the above-described problem of opposite polarity, and processing (removal) of paper dust accumulated on the paper dust collecting member becomes a problem. In particular, in a state where a large amount of paper dust is accumulated, there is a possibility that the paper dust may be scattered around by a slight vibration or impact, and there is a problem in maintaining long-term performance.

<< 3. Problems to be solved by the present invention >>
The present invention has been made in view of the various problems described above, and its object is to say that foreign matter (hereinafter referred to as “paper dust or the like”) such as paper dust or dust on the ink jet recording head without deteriorating the recording quality. ) Is reliably prevented.

  A first aspect of the present invention for solving the above problems is a liquid ejecting means for ejecting a liquid onto an ejected medium, and an ejected medium support means for supporting the ejected medium that is disposed opposite to the liquid ejecting means. A predetermined portion on the liquid ejecting means side in an end region of the ejected medium in a second direction orthogonal to the first direction that is the transport direction of the ejected medium, and The same potential forming means having the same potential as the predetermined portion on the ejected medium support means side is provided, and the predetermined portion on the liquid ejecting means side and the target in the region excluding the end region in the second direction. It is characterized in that a potential difference is formed with a predetermined part on the ejection medium support means side.

  According to this aspect, since the predetermined portion on the liquid ejecting means side and the predetermined portion on the ejected medium support means side have the same potential in the end region of the ejected medium, the liquid ejecting means and the ejected medium The electric field between the supporting means and the support means is very weak or almost no electric field is formed (hereinafter, such a state is referred to as a no-field state for convenience). That is, the end of the ejected medium where paper dust or the like is most marked is placed in the no-electric field formed between the liquid ejecting means and the ejected medium supporting means, and adheres to the end of the ejected medium. As a result, the paper dust and the like are prevented from being scattered and flying, and most of the paper dust is discharged to the outside of the apparatus together with the medium to be ejected while adhering to the end of the medium to be ejected. Accordingly, it is possible to reliably prevent paper dust and the like from flying and adhering to the liquid ejecting means.

  In the area excluding the end area of the ejection medium, a potential difference is formed between the predetermined part on the liquid ejection means side and the ejection medium support means. An electric field is positively formed between the liquid ejecting means and the ejected medium indicating means, and the liquid ejected from the liquid ejecting means is attracted to the ejected medium by the Coulomb force and is surely landed. Accordingly, it is possible to prevent the liquid jet quality from being deteriorated, and to solve the problems associated with the liquid floating as a mist.

  According to a second aspect of the present invention, in the first aspect, the equipotential forming means sets a predetermined portion on the liquid ejecting means side and the ejected medium to the same potential.

  According to this aspect, in the end region of the ejected medium, the predetermined portion on the liquid ejecting means side and the ejected medium are further set to the same potential, so that there is no electric field between the liquid ejecting means and the ejected medium. As a result, the end of the ejected medium is placed in a complete non-electric field region, and the paper dust attached to the end of the ejected medium is more reliably prevented from scattering and flying, most of which As it is attached to the end of the ejected medium, it is discharged out of the apparatus together with the ejected medium. Accordingly, it is possible to more reliably prevent paper dust or the like from adhering to the liquid ejecting means.

  According to a third aspect of the present invention, in the first or second aspect, the region where the predetermined portion on the liquid ejecting means side and the predetermined portion on the ejected medium support means side have the same potential is the second aspect. In the direction, a plurality of ejecting media having a plurality of sizes are provided according to the size.

  According to this aspect, the region where the predetermined portion on the liquid ejecting means side and the predetermined portion on the ejected medium support means side have the same potential is the size of the ejected medium having a plurality of sizes in the second direction. Accordingly, a plurality of mediums to be ejected can be accommodated.

  According to a fourth aspect of the present invention, in the second or third aspect, the equipotential forming unit includes a predetermined part on the liquid ejecting unit side, a predetermined part on the ejected medium supporting unit side, an ejected medium, These are made to have the same potential by grounding them.

  According to this aspect, the equipotential forming means connects the predetermined portion on the liquid ejecting means side, the predetermined portion on the ejected medium support means side, and the ejected medium to each other by grounding them. Therefore, no potential generating means is required, and the cost of the apparatus can be reduced.

  According to a fifth aspect of the present invention, in any one of the second to fourth aspects, the equipotential forming means includes a contact portion that is in electrical contact with an end region of the ejection target medium. However, it is characterized by comprising a roller provided on the upstream side of the liquid ejecting means in the transport path for transporting the ejected medium and responsible for transporting the ejected medium.

  According to this aspect, since the contact portion that comes into contact with the ejection medium in the same potential forming means is constituted by the roller that carries the ejection medium, the structure is simple and low-cost using the existing components. The same potential forming means can be configured.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the predetermined portion on the liquid ejecting means side is a surface facing the ejected medium support means, and the ejected medium support means The predetermined portion on the side is a surface facing the liquid ejecting means.
According to this aspect, on the liquid ejecting means side and the ejected medium support means side, the predetermined portion that is set to the same potential (potential controlled portion) is a surface facing each other, so that the wraparound electric field from the surroundings is suppressed. It is possible to place the paper dust or the like in a non-electric field state more reliably.

  According to a seventh aspect of the present invention, in any one of the first to sixth aspects, an area in the second direction of a predetermined portion on the ejected medium support means side is an area of the ejected medium in the second direction. It includes a position corresponding to at least one side end, extends from the position to the outside and inside of the medium to be ejected, and the medium to be ejected is at least on the side of the one end of the medium to be ejected in the second direction. A line connecting the end position inside the end of the ejected medium at the predetermined portion on the support means side and the end position outside the end of the ejected medium at the predetermined portion of the liquid ejecting means is a target medium It is configured to intersect with.

  According to this aspect, the terminal position inside the end of the ejected medium at the predetermined portion on the ejected medium support means side and the position corresponding to the end of the ejected medium at the predetermined portion of the liquid ejecting means Since the line connecting the outer end position intersects with the ejected medium, it is assumed that the area between the predetermined position on the ejected medium support means side and the liquid ejecting means Even if an electric field is formed, the end of the ejection target medium does not enter the inside of the electric field (details will be described later).

  As described above, the electric field formed between the ejected medium supporting means and the liquid ejecting means set at the same potential is very weak or almost no electric field is formed. In this case, the end area of the ejected medium where paper dust and the like are most noticeably enters, so that the paper dust and the like adhering to the end of the ejected medium may scatter and fly. It is suppressed, and most of it is adhered to the end of the ejected medium and discharged to the outside of the apparatus together with the ejected medium. Accordingly, it is possible to reliably prevent paper dust and the like from flying and adhering to the liquid ejecting means.

FIG. 3 is a schematic side sectional view showing a paper conveyance path of the printer according to the invention. The conceptual diagram for demonstrating the basic idea of this invention. FIG. 3 is a diagram illustrating a charging state in a recording area of the printer according to the invention (first embodiment). FIG. 6 is a diagram illustrating a charging state in a recording area of the printer according to the invention (second embodiment). FIG. 10 is a diagram illustrating a charged state in a recording area of a printer according to the present invention (third embodiment). FIG. 10 is a diagram showing a charged state in a recording area of a printer according to the present invention (fourth embodiment). FIG. 10 is a diagram showing a charging state in a recording area of a printer according to the invention (fifth embodiment). The figure which shows the means which earth-connects a paper edge part area | region. The figure which shows other embodiment of the means to earth-connect a paper edge part area | region. FIG. 10 is a diagram illustrating a charging state in a recording area of a printer according to the present invention (sixth embodiment). Explanatory drawing for demonstrating the problem of a prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, FIG. 1 is a schematic side sectional view showing a paper conveyance path of the inkjet printer 1 according to the present invention, FIG. 2 is a conceptual diagram for explaining the basic idea of the present invention, and FIGS. 3 to 7 and FIG. It is a figure which shows the charging state in the recording area | region of the inkjet printer 1, and is a figure which shows each different embodiment (1st-6th embodiment). FIG. 8 and FIG. 9 are diagrams showing means for grounding the sheet edge region, and showing different embodiments. 3 to 7 and 10 show one side end region of the paper P, and the same configuration is provided for the other side end region. 1 is a second direction (paper width direction) orthogonal to the first direction, which is the paper conveyance direction, and in FIGS. 2 to 7 and 10, the horizontal direction is the second direction. The (paper width direction) and the paper front and back direction are the first direction (paper transport direction). In FIGS. 8 and 9, the vertical direction in the figure is a first direction (paper conveyance direction), and the horizontal direction in the figure is a second direction (paper width direction).

  Hereinafter, an overall configuration of the inkjet printer 1 which is a configuration common to the embodiments will be described with reference to FIG. The ink jet printer 1 includes a paper feeding device 2 at the bottom of the device. A recording paper P as an example of a medium to be ejected is fed from the paper feeding device 2 and is bent and inverted by an intermediate roller 10 to eject liquid. A configuration is provided in which recording is performed by feeding the ink jet recording head 16 as a means.

  More specifically, the paper feeding device 2 includes a paper cassette 3, a pickup roller 7, an intermediate roller 10, a retard roller 11, and guide rollers 12 and 13. A separation slope 5 is provided at a position facing the front end of the recording paper P accommodated in the paper cassette 3 detachably attached to the paper feeding device 2, and the front end of the recording paper P sent out by the pickup roller 7 is provided. By being fed to the downstream side while being in sliding contact with the separation slope 5, the uppermost recording paper P to be fed and the next and subsequent recording papers P to be fed along with this are fed. Preliminary separation takes place.

  The pickup roller 7 constituting the paper feeding means is pivotally supported by a swinging member 6 that can swing in the clockwise direction and the counterclockwise direction of FIG. It is provided so as to be rotationally driven by the power of the drive motor that does not. The pickup roller 7 feeds the uppermost recording paper P from the paper cassette 3 by rotating in contact with the uppermost recording paper P accommodated in the paper cassette 3 when the paper is fed.

  Next, the recording paper P sent out from the paper cassette 3 enters the curve reversal section. In this curve reversal section, these rollers of the intermediate roller 10, the retard roller 11, and the guide rollers 12, 13 are provided.

  The intermediate roller 10 is a large-diameter roller that forms the inside of a curve reversal path that curves and reverses the recording paper P, and is rotated by a drive motor (not shown). Then, by rotating counterclockwise in FIG. 1, the recording paper P is conveyed downstream while being wound.

  The retard roller 11 is provided so as to be capable of being pressed against and separated from the intermediate roller 10 with a predetermined rotational frictional resistance, and is fed by nipping the recording paper P with the intermediate roller 10. The uppermost recording sheet P to be separated from the next and subsequent recording sheets P that are to be double fed along with the recording sheet P are separated.

  Note that a paper return lever (not shown) is provided in the vicinity of the paper feed path, and the recording paper P after the next level stopped by the retard roller 11 is fed to the paper cassette 3 by the paper return lever. It is configured to be returned to.

  The guide rollers 12 and 13 are freely rotatable rollers, and the guide roller 13 assists the sheet feeding by the intermediate roller 10 by nipping the sheet P with the intermediate roller 10.

  The above is the configuration of the paper feeding device 2, and the ink jet printer provided with the paper feeding device 2 further includes the transport driving roller 14 and the transport driven roller 15 on the downstream side of the intermediate roller 10. The transport driving roller 14 is rotationally driven by a drive motor (not shown), and the transport driven roller 15 nips the recording paper P with the transport driving roller 14 and rotates in accordance with the transport of the recording paper P.

  The downstream area of the conveyance drive roller 15 is a recording area for performing recording on the recording paper P. The inkjet recording head 16 as a liquid ejecting unit and the recording paper P and the inkjet recording head 16 by supporting the recording paper P. And a support member 17 as an ejected medium support means that defines a distance between the support member 17 and the target medium.

  The recording paper P is recorded between the ink jet recording head 16 and the support member 17 (recording area), and is discharged to the outside of the apparatus by a discharge means not shown in FIG.

<< Basic Idea of the Present Invention >>
The above is the general configuration of the ink jet printer 1, and the basic idea of the present invention will be described below with reference to FIG. In FIG. 2, reference numeral 16 a denotes a metal nozzle plate formed with a plurality of ink discharge nozzles (not shown) that forms the first side facing the support member 17 in the inkjet recording head 16. Reference numeral 17a denotes a rib formed in the support member 17 and extending in the paper transport direction (first direction: front and back direction in FIG. 2). The rib 17a is in the paper width direction (second direction: left-right direction in FIG. 2). ), With a suitable interval, and the recording paper P is supported by the ribs 17a.

  Reference sign Pe indicates a paper edge (edge in the paper width direction), and reference sign d indicates paper dust or the like adhering to the paper edge Pe. Further, symbols s and s ′ indicate ink droplets ejected from the ink jet recording head 16 toward the recording paper P, and the ink droplet s is a central region excluding the paper edge region (right side from the position X in FIG. 2). Ink droplets ejected in the paper, and an ink droplet s ′ represents an ink droplet ejected in the paper edge region.

  Reference numeral V1 denotes a potential difference between the nozzle plate 16a and the support member 17 (surface facing the nozzle plate 16a), reference numeral V2 denotes a potential difference between the nozzle plate 16a and the recording paper P, and reference numeral V3 denotes a support member. 17 shows the potential difference between the recording paper P and the recording paper P (surface facing the recording paper P).

  In the present invention, at least the potential difference V1 is zero in the paper edge region, and no electric field is applied between the nozzle plate 16a and the support member 17. Thereby, the Coulomb force due to the electric field between the nozzle plate 16a and the support member 17 does not act on the paper dust d and the paper dust d is prevented from flying toward the nozzle plate 16a.

  In another embodiment of the present invention, in addition, the potential difference V2 is set to zero in the paper edge region, and no electric field is applied between the nozzle plate 16a and the recording paper P. Thereby, the Coulomb force due to the electric field between the nozzle plate 16a and the recording paper P does not act on the paper dust d and the paper dust d is further suppressed from flying toward the nozzle plate 16a.

Regarding the potential difference V3 in the sheet edge region, when the potential difference V1 is set to zero and the potential difference V2 is set to zero, the potential difference V3 also becomes zero, and the flying of paper dust or the like d to the support member 17 side can be prevented. .
The above is the basic idea of the present invention.

<< First Embodiment >>
Hereinafter, the charging state in the recording area (first embodiment) will be described with reference to FIG. In this embodiment and the second to fourth embodiments described later, the ink jet recording head 16 is a so-called line head formed in a length that covers the paper width, and the ink jet recording head 16 is moved in the paper width direction. Recording can be performed only by moving the recording paper P in the transport direction (first direction) without reciprocating in the (second direction).

  In FIG. 3, reference numerals 20A and 20B denote the same potential forming means. The same potential forming means 20A includes a first side facing the support member 17 in the ink jet recording head 16, that is, the nozzle plate 16a and the nozzle plate 16a in the support member 17 in the paper end region including the end Pe of the recording paper P. And the second side facing each other are set to the same potential.

  More specifically, an electrode plate (for example, a SUS plate having a width of about 20 mm) 21 is provided in an end region of the recording paper P in the support member 17, and the electrode plate 21 and the nozzle plate 16a are connected to ground. Has been. As a result, the potential difference between the nozzle plate 16a and the support member 17 becomes zero, and an electric fieldless state is formed. The electrode plate 21 is configured to be at least a length and an arrangement position for covering the inkjet recording head 16 in the first direction.

  On the other hand, the recording paper P is similarly grounded by the same potential forming means 20B, and therefore, the potential difference between the recording paper P, the nozzle plate 16a, and the support member 17 is zero in the paper edge region. An electric field state is formed. The equipotential forming means 20B can be constituted by forming a roller upstream of the recording area including the conveyance driving roller 14 with a conductive material and grounding, or constituted by a conductive brush or the like. can do.

  On the other hand, the central region (the region on the right side of the X position in FIG. 3) excluding the end region in the width direction of the recording paper P is in a state where a potential difference, that is, an electric field can be formed between the nozzle plate 16a and the support member 17. However, the potential difference (electric field strength) is not controlled (no control). Note that an electric field is formed between the nozzle plate 16a and the support member 17 in the central region excluding the paper edge region, but the lines of electric force are not shown in order to avoid complication of the drawing (FIG. 4 to 7 in the same manner).

  That is, the potential difference (electric field strength) between the nozzle plate 16a and the support member 17 is not controlled by providing a dedicated potential difference generating means (no control), but the support member 17 is formed of a resin material. Since it has a property as a dielectric, it is charged by friction with the recording paper P, and as a result, a potential difference (electric field) can be formed with the nozzle plate 16a.

  The circled signs “+” and “−” in FIG. 3 indicate the charging polarity (the same applies to FIGS. 4 to 7). In the example of FIG. 3, the support member 17 is negatively charged by frictional charging. Is shown. Accordingly, since the support member 17 is negatively charged in the central region excluding the end region of the recording paper P, a positive charge appears on the support member 17 side of the nozzle plate 16a due to electrostatic induction, and the ink droplet s appears on the nozzle plate. Charges to the same positive pole as 16a.

  The ejected ink droplet s is attracted to the recording paper P side between the nozzle plate 16a and the recording paper P by Coulomb force F (= qE: q is the charge of the ink droplet s and E is the electric field). It will surely land on the recording paper P. Even if the support member 17 is positively charged, the ink droplet s is negatively charged due to electrostatic induction, so that it is eventually attracted to the recording paper P in the same manner as described above.

  Next, since the end region of the recording paper P is set to an electric field-free state as described above, the Coulomb force does not act on the paper dust or the like d, and therefore the paper dust or the like d does not scatter or fly. The paper is discharged to the outside of the apparatus while remaining attached to the paper edge Pe. In the end region of the recording paper P, the ejected ink droplet s ′ does not receive the Coulomb force due to the electric field and is not attracted to the recording paper P by the Coulomb force. Since it does not receive the Coulomb force in the direction that impedes the landing, it lands on the recording paper P by the kinetic energy f generated by the ejection.

As described above, according to the present embodiment, the end region of the recording paper P is set to the same potential (ground potential) between the ink jet recording head 16, the support member 17, and the recording paper P, and no electric field state is obtained. Therefore, the paper edge portion Pe to which the paper powder or the like d adheres most is placed in the non-electric field region. Accordingly, the paper dust or the like d adhering to the paper edge Pe is prevented from scattering and flying, and most of it is discharged to the outside of the apparatus together with the recording paper P while adhering to the paper edge Pe. Accordingly, it is possible to reliably prevent paper dust and the like d from adhering to the nozzle plate 16a.
Note that the width of the paper edge region (distance from the paper edge to the position X) can be adjusted as appropriate according to the state of adhesion of paper powder or the like d, and can be set to about 2 mm, for example, where adhesion is most remarkable. Alternatively, it can be set within a range (for example, about 2 to 5 mm) provided with a slight margin, that is, it can be appropriately adjusted according to the degree of adhesion of paper powder or the like d. The electrode plate 21 is configured to have a width and an arrangement position that covers such a paper edge region in the second direction.

  In addition, since a potential difference is formed between the nozzle plate 16a and the support member 17 in the central region excluding the paper edge region, an electric field is formed in the central region, and the inkjet The ink droplets s ejected from the recording head 16 will surely land on the recording paper P, and the problem of mist floating can be solved.

<< Second Embodiment >>
Hereinafter, a second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the already demonstrated component, and suppose that the description is abbreviate | omitted below (it is the same also in other embodiment described below).

  In the present embodiment, the difference from the first embodiment described with reference to FIG. 3 is that the potential difference generating means 22 is formed between the nozzle plate 16a and the support member 17 in the central region except the paper edge region. The potential difference (electric field strength) is controlled.

  That is, the electrode plate 23 is provided between the ribs 17a and 17a in the central region of the paper support member 17 excluding the paper edge region. This electrode plate 23 is connected to a positive pole (for example, +500 V) of the potential difference generating means 22, thereby forming a potential difference, that is, an electric field between the paper support member 17 and the nozzle plate 16 a.

As a result, the ink droplet s discharged from the inkjet recording head 16 is negatively charged when the nozzle plate 16a is negatively charged by electrostatic induction, and is attracted to the support member 17 side by the Coulomb force. Land on the recording paper P.
In this manner, since the potential difference (electric field strength) in the central region excluding the paper edge region is controlled, it is possible to more reliably prevent the ink droplets s from becoming mist in the central region. In the present embodiment, the electrode plate 23 is connected to the positive pole of the potential difference generating means 22, but may be connected to the negative pole.

<< Third Embodiment >>
Hereinafter, a third embodiment of the present invention will be described with reference to FIG. This embodiment is different from the second embodiment described with reference to FIG. 4 in that an ink absorbing material 25 is provided on the electrode plates 21 and 23. Even if ink droplets are ejected by the ink absorbing material 25 to areas outside the recording paper P (for example, during flushing when ink is ejected idle or during borderless printing), this can be reliably caught. The problem of mist floating can be solved.

  Note that the upper surface of the ink absorbing material 25 is located below the top of the rib 17a, thereby preventing the ink absorbing material 25 from fouling the back surface of the recording paper P. For example, the distance from the lower surface of the nozzle plate 16a to the ink absorbing material 25 is about 2 to 4 mm, and the distance from the lower surface of the nozzle plate 16a to the upper surface of the recording paper P is about 1 mm (recording). The thickness of the paper P is 1 mm or less).

  Here, the ink absorbing material 25 is formed so as to have a property as a conductor in the present embodiment, and has a conductivity of, for example, a surface resistivity of 102 to 108 Ω / □ (for example, about 105 Ω / □). . Specifically, a conductive material such as polyethylene or polyurethane mixed with a conductive material such as metal or carbon is foamed, and a conductive material such as metal or carbon is adhered to a resin foam such as polyethylene or polyurethane. A plated or plated one can be used. Moreover, what impregnated electrolyte solution to resin foam materials, such as polyethylene and a polyurethane, can also be used.

  By imparting conductivity to the ink absorbing material 25, the potential of the outermost surface of the ink absorbing material 25 (the outermost surface on the nozzle plate side) can be reliably controlled. Accordingly, an electric field-free state can be surely formed in the paper edge region, and mist formation of the ink droplets s can be prevented by accurately controlling the electric field in the central region excluding the paper edge region.

<< Fourth Embodiment >>
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG. The present embodiment differs from the third embodiment described with reference to FIG. 5 in that the support member (indicated by reference numeral 17 ′) has conductivity (for example, a surface resistivity of about 102 to 108 Ω / □). Accordingly, the electrode plates 21 and 23 and the same potential forming means 20B for grounding the recording paper P are omitted, and an ink absorbing material 26 having an insulating property is provided in the central region excluding the paper end region. It is a point.

  That is, since the support member 17 ′ itself is a conductor and is connected to the ground, the electrode plate 21 is not necessary, and the apparatus configuration can be simplified and the cost can be reduced. As the support member 17 ′, for example, a resin in which a conductive material such as metal or carbon is mixed can be used. In addition, after forming with an insulating material, you may adhere electroconductive materials, such as a metal and carbon, to the surface.

  In the fourth embodiment, since the recording paper P is in contact with the ribs 17a ′ of the support member 17 ′, the nozzle in the edge region of the paper is not provided without separately providing a means for controlling the potential of the recording paper P. The plate 16a, the recording paper P, and the support member 17 ′ can be set to the same potential (no electric field).

  Further, since the ink absorbing material 26 having insulating properties is provided in the central region excluding the paper edge region, an electric field is formed by charging the ink absorbing material 26 (however, the potential difference is not controlled), and the ink jet recording head. The ink droplets s ejected from the ink 16 are attracted toward the ink absorbing material 26 by the Coulomb force, that is, the ink droplets s surely land on the recording paper P, and the problem of mist floating can be solved.

<< Fifth Embodiment >>
Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG. This embodiment is different from the first embodiment described with reference to FIG. 3 in that the ink jet recording head (indicated by reference numeral 16 ′) is a serial type that ejects ink droplets while moving in the paper width direction. is there.

  Even in such a serial type ink jet printer, the same potential between the ink jet recording head 16 ′, the support member 17, and the recording paper P in the end region of the recording paper P is the same as in the first embodiment. Thus, since there is no electric field, the paper edge Pe to which paper powder or the like d adheres most is placed in the electric field region. Accordingly, the paper dust or the like d adhering to the paper edge Pe is prevented from scattering and flying, and most of it is discharged to the outside of the apparatus together with the recording paper P while adhering to the paper edge Pe. Accordingly, it is possible to reliably prevent the adhering of paper dust or the like d to the nozzle plate 16a '.

  In addition, since a potential difference is formed between the nozzle plate 16a ′ and the support member 17 in the central region excluding the paper edge region, an electric field is formed in the central region. The ink droplets s discharged from the ink jet recording head 16 will surely land on the recording paper P, and the problem of mist floating can be solved.

<< Other variations >>
(1) Means for forming the same potential in the paper edge area
In each of the above embodiments, in order to form an electric fieldless state by setting the nozzle plate 16a (16a ′), the recording paper P, and the support member 17 (17 ′) to the same potential in the paper edge region, Although the components are connected to the ground, an electric field can be formed as long as the potential is the same. Therefore, the present invention is not limited to the ground connection, and an arbitrary voltage having an arbitrary polarity may be applied.

  In each of the above embodiments, the nozzle plate 16a (16a '), the recording paper P, and the support member 17 (17') have the same potential in the paper edge region. For example, the nozzle plate 16a (16a ') And the supporting member 17 (17 ') are set to the same potential and the recording paper P is not controlled in potential (floating), but the effect of preventing adhesion of predetermined paper dust and the like (preventing adhesion of paper dust and the like to the nozzle plate) Effect).

In each of the above embodiments, the area corresponding to the edge of a certain size recording paper (for example, A4 size) is in an electric field-free state. However, no electric field is applied to support a plurality of recording paper sizes. A plurality of areas can be arranged according to the size (in the paper width direction).
In this case, in the case of small-size paper, the area outside the area set to the no-electric field state (paper edge area) is an electric field forming area, so that scattering of ink mist is prevented in the outer area of the recording paper P. Can do.

(2) Potential Difference in Central Region Excluding Paper Edge Region In each of the above embodiments, a potential difference (electric field) is mainly provided as a countermeasure against mist floating in the central region excluding the paper edge region. Even if the above is not provided, it is possible to obtain the effect of preventing the scattering and flying of d such as paper dust at least in the above-described paper edge region.

(3) Nozzle plate In each of the above embodiments, a water repellent film may be provided on the surface of the nozzle plate 16a (16a '). Here, if a conductive water repellent film is used, charging of the water repellent film can be suppressed, paper dust or the like can be prevented from adhering to the nozzle plate 16a (16a '), and the potential on the nozzle plate side can be suppressed. Can be reliably controlled.

  Also, if an insulating water-repellent film is used, the image power of the nozzle plate 16a (16a ') made of a metal such as SUS (when charged paper powder or the like approaches the nozzle plate, (Phenomenon in which opposite charges appear and attract each other) can be reduced, and it is possible to prevent paper dust or the like that has risen near the nozzle plate from being attracted to the nozzle plate 16a (16a ').

  The predetermined portion for applying (controlling) the potential is preferably the support member 17 side of the inkjet recording head 16, that is, the nozzle plate 16a, and more specifically, the nozzle surface which is the surface facing the support member 17. Is preferred. Thereby, since the potential of the nozzle surface closest to the recording paper P is controlled, it is possible to suppress a wraparound electric field from the surroundings and to effectively prevent adhesion of paper dust or the like to the nozzle surface. . This also applies to the support member 17 side, and it is preferable that the predetermined portion for controlling the potential is a surface facing the nozzle plate 16a.

(4) Electrode plate In each of the above-described embodiments (particularly, the first, second, and fifth embodiments), the electrode plates 21 and 23 provided on the support member 17 may be electrically conductive as shown in FIGS. The ink absorbing member 25 can be used instead.

  The electrode plates 21 and 23 may be configured to contact the recording paper P, but are preferably disposed with a predetermined gap between the electrode plates 21 and 23 so as not to contact the recording paper P. . Thereby, it is possible to suppress paper dust from accumulating on the electrode plates 21 and 23, and it is possible to suppress not only physical adhesion but also adhesion due to mirror image force especially for charged paper powder and the like.

(5) Grounding means for recording paper In each of the above embodiments, even if the potential difference between the nozzle plate 16a (16a ′) and the recording paper P is not zero, the nozzle plate 16a (16a ′) and the support member If the potential difference with respect to 17 (17 ′) is set to zero, a predetermined paper dust scattering prevention effect can be obtained.

  In each of the above-described embodiments (particularly, each of the first to third and fifth embodiments), the recording paper P can be grounded by various means, for example, a conductive material that is grounded at an arbitrary place. A brush can also be arranged and brought into contact with the recording paper P.

  Further, it is also possible to connect to the ground via each roller arranged on the paper transport path. FIG. 8 shows an example thereof, which can be grounded via a transport driven roller indicated by reference numeral 15A. A conveyance driven roller indicated by reference numeral 15A is a conveyance driven roller provided at the end in the sheet width direction, and is formed of a conductive material and connected to the ground. Therefore, the end region (indicated by reference numerals E1 and E2) of the recording paper P is grounded and is configured to be focused on the ground potential.

  Reference numeral 18 denotes an upper guide member that supports the transport driven rollers 15A and 15B so as to be freely rotatable. Moreover, the conveyance driven roller shown with the code | symbol 15B is a roller formed with the insulating material. However, instead of this, a transport driven roller 15A formed of a conductive material and connected to the ground may be adopted over the entire sheet width direction.

  The conveyance drive roller 14 to which the conveyance driven rollers 15A and 15B come into pressure contact is formed by attaching wear-resistant particles to the surface of the metal shaft body so as to increase the frictional force with the recording paper P. Reference numeral 14a is the wear resistance. The metal surface to which the conductive particles are not attached, reference numeral 14b, indicates a high friction surface (having a property as a dielectric in the present embodiment) to which the wear-resistant particles are attached.

  Therefore, as shown in FIG. 9, the end face of the recording sheet P is formed by extending the metal surface 14a to the inside of the sheet conveying area, forming the sheet end areas E1 and E2 by the metal surface 14a and grounding them. The areas E1 and E2 can be grounded, and the paper edge area can be focused on the ground potential.

(6) Applying electric charge to ink droplet In each of the above embodiments, the ink droplet is charged by the induced charge via the nozzle plate 16a (16a '), but an ink storage chamber (for example, an ink cartridge) that stores ink ) To the nozzle plate 16a (16a ′), the ink droplet may be charged at an arbitrary position in the ink flow path. For example, a part or all of the inner wall of the ink storage chamber may be made of a conductive member, and the charge may be applied to the ink through the inner wall.

  For example, in the second embodiment shown in FIG. 4 or the third embodiment shown in FIG. 5, the polarity given to the ink at this time is the potential difference generating means 22 on the support member 17 side in the central region excluding the paper edge region. Since it is connected to the positive polarity of, negative polarity should be given. In addition, when the potential on the support member 17 side is not controlled in the central region excluding the paper edge region, that is, when charging is performed by frictional charging, contact charging, or the like, the material forming the supporting member 17 is positively charged. The polarity to be given to the ink may be determined based on which of the negative and positive polarities is likely to be charged.

  In addition, by applying the same potential to the ink as the liquid as the supporting member 17 side (or recording paper), the electric field between the ink jet recording head 16 and the supporting member 17 (or recording paper) is extremely weakened in the end region of the paper. Therefore, it is possible to constitute a measure for preventing paper dust from adhering to the nozzle plate 16a. That is, for example, the nozzle plate 16a is not limited to a conductor such as a metal, but may be formed of a dielectric such as silicon, acrylic, or polyimide. In this case, if the potential of the ink inside the head is not controlled, the electric field due to the potential difference between the ink inside the head and the support member 17 may have a strong influence on the paper dust, and the paper dust may fly to the nozzle plate 16a side. is there. However, such a problem can be solved by applying the same potential to the ink inside the head as that on the support member 17 side.

  Further, when the nozzle plate 16a is formed of a dielectric, as a configuration for applying a potential to the ink inside the head, only the ink flow path portion (portion in contact with the ink) in the nozzle plate is formed of a conductive member. It is also possible to apply a potential to the ink via the. For example, when the nozzle plate has a laminated structure, the ink flow path portion may be composed of a conductive member in all layers, or at least one of the layers may be composed of the ink flow path portion with a conductive member. Also good.

(7) Configuration Considering Electric Field Formed by Region Other than Electrode Plate Arrangement Region in Support Member In each of the above embodiments, the electric field formed by the region other than the electrode plate placement region in support member 17 is considered. Thus, it is possible to more reliably prevent paper dust and the like from being scattered. Hereinafter, this will be described with reference to FIG. FIG. 10 shows a modification of the first embodiment shown in FIG.

  Here, in FIG. 10, a point R1 is a position corresponding to the end of the sheet on the electrode plate 21 (a position of the support member 17 when a perpendicular line is drawn from the end of the sheet toward the support member 17). 10 indicates the end position on the right side), and the point R2 indicates the end position on the nozzle plate 16a on the outside of the sheet (left side in FIG. 10) from the position Qe corresponding to the end of the sheet. A line indicated by reference numeral E1 indicates a line connecting the point R1 and the point R2.

  For example, in FIG. 10, the paper inner side (right side in FIG. 10) of the support member 17 in the paper from the electrode plate 21 is an area formed of a resin material, and therefore, in the area inside the paper from the line E <b> 1 (right side in FIG. 10) There is a possibility that an electric field is formed between the support member 17 and the nozzle plate 16a. That is, even if the paper edge region to which paper dust or the like d is attached is sandwiched between the electrode plate 21 and the nozzle plate 16a, the above-described electric field is generated. When the ink enters, there is a risk that paper dust or the like d adhering to the edge area of the paper will be scattered and fly toward the nozzle plate 16a.

  However, by configuring the line E1 so as to be located on the inner side of the sheet (right side in FIG. 10) than the sheet end area, that is, the line E1 intersects with the sheet, the sheet end area can be surely placed in the no electric field state. Can be put. As a result, it is possible to reliably prevent the paper dust and the like d adhering to the paper edge area from being scattered and flying toward the nozzle plate 16a.

  In this embodiment, the line E1 passes through the inside of the sheet with respect to the area of the distance w inward from the end of the sheet. However, the line E1 passes through at least the end of the sheet (edge). If it is comprised, the predetermined | prescribed paper dust scattering prevention effect can be acquired. Further, the distance w can be set to, for example, about 2 mm where adhesion is most remarkable in consideration of the degree of adhesion of paper powder or the like d, or a range with a slight margin (for example, w = 2). About 5 mm), that is, it can be appropriately adjusted according to the degree of adhesion of paper powder or the like d.

  In each of the above embodiments, the configuration of the present invention is applied to both the one end and the other end of the paper P. However, the present invention is not limited to such a configuration. Even when the configuration of the present invention is applied only to the one side end region of P, it goes without saying that the effect is obtained in the one side end region.

DESCRIPTION OF SYMBOLS 1 Inkjet printer, 2 Feeding device, 3 Paper cassette, 5 Separation slope, 6 Oscillating member, 7 Pickup roller, 10 Intermediate roller, 11 Retard roller, 12, 13 Guide roller, 14 Transport drive roller, 15 Transport driven roller, 16
Inkjet recording head, 16a nozzle plate, 17 guide member, 17a rib, 18 upper guide member, 20A, 20B equipotential forming means, 21 electrode plate, 22 potential difference forming means, 23 electrode plate, 25 ink absorbing material (conductive), 26 Ink absorbing material (insulating), P Recording paper

Claims (6)

Liquid ejecting means for ejecting liquid onto the ejection target medium;
An ejected medium support means for supporting an ejected medium, which is disposed opposite to the liquid ejecting means ,
A predetermined portion on the liquid ejecting means side and a predetermined portion on the ejected medium support means side in an end region of the ejected medium in a second direction orthogonal to the first direction that is the transport direction of the ejected medium. While having the same potential forming means for making the same potential,
In the region excluding the end region in the second direction, a potential difference is formed between a predetermined portion on the liquid ejecting means side and a predetermined portion on the ejected medium support means side ,
The region in the second direction of the predetermined portion on the ejection medium support means side includes a position corresponding to at least one side end portion of the ejection medium in the second direction, and the outside of the ejection medium from the position and Extending inward,
At least the one side end portion of the ejected medium in the second direction, a terminal position inside the end portion of the ejected medium at a predetermined portion on the ejected medium support means side, and a predetermined position of the liquid ejecting means In the part, the line connecting the end position outside the end of the ejection medium is configured to intersect the ejection medium.
A liquid ejecting apparatus. The liquid ejecting apparatus according to claim 1, wherein the same potential forming unit sets a predetermined portion on the liquid ejecting unit side and the target medium to have the same potential.
A liquid ejecting apparatus. 3. The liquid ejecting apparatus according to claim 1 , wherein a plurality of regions in which the predetermined part on the liquid ejecting unit side and the predetermined part on the ejected medium supporting unit side have the same potential are provided in the second direction. A plurality of the mediums to be ejected are provided according to the size of the ejected medium.
A liquid ejecting apparatus. 4. The liquid ejecting apparatus according to claim 2, wherein the same potential forming unit grounds a predetermined portion on the liquid ejecting unit side, a predetermined portion on the ejected medium supporting unit side, and the ejected medium. Make them the same potential by connecting them,
A liquid ejecting apparatus. 5. The liquid ejecting apparatus according to claim 2, wherein the same potential forming unit includes a contact portion that is in electrical contact with an end region of the ejection target medium.
The contact portion is configured by a roller provided on the upstream side of the liquid ejecting unit in a transport path for transporting the ejected medium and responsible for transporting the ejected medium.
A liquid ejecting apparatus. 6. The liquid ejecting apparatus according to claim 1 , wherein the predetermined part on the liquid ejecting unit side is a surface facing the ejected medium supporting unit,
The liquid ejecting apparatus according to claim 1, wherein the predetermined portion on the ejected medium support means side is a surface facing the liquid ejecting means.

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