JP2005096207A - Inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus which can appropriately jet an ink even under a low driving electric voltage in an electrostatic inkjet recording, and in which concentration and jetting condition of charged particles are stabilized even when recording is continuously performed at a high speed. <P>SOLUTION: The problem can be solved by providing an ozone removing means for removing ozone in the apparatus from the vicinity of an inkjet head. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an inkjet recording apparatus that performs recording by ejecting ink containing charged particles using an electrostatic field.

  Electrostatic ink jet recording uses an ink composition (hereinafter referred to as ink), which contains a color material and in which charged fine particles (color material particles) are dispersed in an insulating dispersion medium, and image data. Accordingly, by applying a predetermined driving voltage to the control electrodes (ejection electrodes) arranged in the ejection portions of the inkjet head, the ink (ink droplet) is ejected and controlled using electrostatic force, An image corresponding to the image data is recorded on a recording medium.

Such an electrostatic ink jet requires a high voltage of several kV for ink ejection.
Normally, in an electrostatic ink jet, a pulse power source is used, and on / off of application of a pulse voltage as a drive voltage to a control electrode is controlled to turn on / off the discharge. Such a high voltage pulse voltage Is very expensive and is difficult to use for a general-purpose device.

Therefore, in an apparatus that performs electrostatic ink jet recording, a DC voltage that does not eject ink is always applied to the control electrode as a bias voltage, and the drive voltage is superimposed on the bias voltage for ejection. Thus, a method for reducing the drive voltage is used.
According to this method, the driving voltage for ejection can be several hundred volts. However, the withstand voltage of a driving element such as a driver still needs to correspond to several kV, and it is inevitable that the device becomes expensive.

On the other hand, Patent Document 1 discloses an ink jet recording in which electrostatic charging is performed by charging a recording medium with a charge opposite to that of the colorant particles of ink and using this as a bias voltage for the control electrode. An apparatus is disclosed.
According to this method, the pulse voltage as the drive voltage is about several hundred volts, and the withstand voltage of the drive element only needs to correspond to this level of voltage. Moreover, according to this electrostatic ink jet recording method, the effect of the bias voltage is superimposed, and the ink ejected by the migration of the color material particles is concentrated as a result. A high-resolution image that does not depend on the recording medium can be recorded.
Japanese Patent No. 3288379

However, in the ink jet recording apparatus disclosed in Patent Document 1, the concentration of the color material particles may become unstable or the ink discharge state may become unstable. In particular, this tendency becomes significant when continuous recording is performed at high speed.
Accordingly, an object of the present invention is to solve the above-mentioned problems, and in electrostatic ink jet recording, by charging a voltage as a bias voltage to a recording medium, ink can be properly discharged even at a low driving voltage. An object of the present invention is to provide an ink jet recording apparatus in which charged particles are concentrated and the ejection state is stable even when continuous recording is performed at high speed.

  To achieve the above object, according to the present invention, an inkjet head that discharges ink onto a recording medium by applying an electrostatic force to ink containing charged particles, a charging unit for charging the recording medium, and an apparatus There is provided an ink jet recording apparatus comprising ozone removing means for removing ozone in the vicinity of an internal ink jet head.

Further, it is preferable to provide a charge eliminating means for discharging the recording medium after image recording, and the ozone removing means is preferably driven in synchronism with the charging means or further the charge removing means.
The ozone removing means is preferably an exhaust means for exhausting the outside of the apparatus from the vicinity of the charging means or further the static eliminating means, and the exhaust means preferably has an ozone treatment means in the exhaust path. In addition, the ozone removing means is preferably an air blowing means for blowing gas outside the apparatus to the vicinity of the inkjet head, and preferably has an ozone treatment means in an exhaust part to the outside of the apparatus. The ozone removing means is preferably an ozone treatment means arranged in the vicinity of the charging means or further the charge eliminating means, preferably a heating means for heating the ozone treatment means, and further, the ink jet A heat fixing means for heat fixing the image after image recording by the head; Preferred heat to a means for transmitting to said ozone treatment means.

According to the above-described ink jet recording apparatus of the present invention, in the electrostatic ink jet, by charging the recording medium with a voltage serving as a bias voltage, it is possible to properly eject ink even with a low driving voltage (pulse voltage). The apparatus cost can be greatly reduced, and even when continuous recording is performed at high speed, charged particles can be concentrated and the ejection state can be stabilized, and high-quality image recording can be performed with high productivity.
In addition, preferably, by having the ozone treatment means, it is possible to prevent the ozone from being discharged to the outside of the apparatus and to eliminate the adverse effect on the installation environment of the ink jet recording apparatus. Further, by having a heating means for heating the ozone treatment means, the effect of the ozone treatment means can be obtained stably over a long period of time, and as the heating means, a new heat can be obtained by utilizing the residual heat of the image heat fixing means. The installation of a heat source is unnecessary and energy saving can be achieved.

  Hereinafter, an electrostatic ink jet recording apparatus of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 is a schematic configuration diagram of a first embodiment of an electrostatic ink jet recording apparatus of the present invention. The electrostatic ink jet recording apparatus 10 shown in the figure includes an ink (ink composition) containing a color material and having charged fine particles (hereinafter referred to as color material particles) dispersed in an insulating solvent (carrier liquid). The ink (liquid droplets) is ejected by applying an electrostatic force to the ink, and C (cyan), M (magenta), Y (yellow) depending on the supplied image data. The four color inks of K and K (black) are modulated by the corresponding ejection heads and ejected to record a full color image of four colors. Further, the apparatus of the illustrated example can perform image recording on both sides of a recording medium (recording paper) P as necessary.
Such an electrostatic ink jet recording apparatus 10 (hereinafter referred to as recording apparatus 10) includes a recording medium P holding means 12, a conveying means 14, a recording means 16, a solvent recovery means 18, an ozone removing means 20, And a housing 22.

  First, the holding means 12 for the recording medium P includes a paper feed tray 24 that holds the recording medium P before recording, a feed roller 26, and a discharge tray 28 that holds the recording medium P after recording.

The paper feed tray 24 is detachably loaded in a predetermined loading portion on the bottom surface on the left side in the figure inside the housing 22 in a state where a large number of unrecorded recording media P are accommodated.
The feed roller 26 is disposed corresponding to an end portion on the take-out side of the paper feed tray 24 loaded in the loading unit, and supplies a single recording medium P to the transport unit in accordance with a recording start instruction.

On the other hand, the discharge tray 28 is detachably loaded into a predetermined loading section on the right side in the drawing outside the housing 22.
The recording medium P after recording is transported by the transport means 14 and discharged from the discharge portion into the paper discharge tray 28.

Next, the conveying means 14 for the recording medium P will be described.
The conveyance means 14 conveys the paper from the paper feed tray 24 to the discharge tray 28 through a predetermined path. The conveyance rollers 31a, 31b, and 31c, the conveyance belt 32, the belt rollers 34a and 34b, and the conductive platen 36 are provided. , A charging device 38a and 38b for the recording medium P, a static eliminating device 40 for the recording medium P, a switching claw 43, guides 44a, 44b and 44c, a fixing roller pair 46, and a reverse roller pair 47.

  The conveyance roller 31 a is provided on the conveyance path of the recording medium P between the feed roller 26 and the recording unit 16.

  The recording medium P taken out from the paper feed tray 24 by the feed roller 26 is nipped and conveyed by the conveyance roller 31a and the conveyance belt 32 in the right direction in the figure.

The charging device 38 a for the recording medium P includes a scorocolon charger 48 and a negative high-voltage power supply 50. The charging device 38 a is disposed on the conveyance path of the recording medium P between the conveyance roller 31 a and the recording unit 16. The negative terminal of the negative high voltage power supply 50 is connected to the scorotron charger 48, and the positive terminal is grounded.
Further, the scorotron charger 48 is covered with a hood 68 a connected to the duct 68. The duct 68 and the hood 68a will be described later.

  The surface of the recording medium P is uniformly charged to a predetermined negative high potential by a scorotron charger 48 connected to a negative high voltage power supply 50, and a constant DC bias voltage (for example, about −1.5 kV) is always applied. It will be in the state. By applying this bias voltage to the recording medium P, the driving voltage (pulse voltage) applied to a control electrode (ejection electrode) described later can be reduced by causing the recording medium P to act as a counter electrode. Further, by applying this bias voltage, the recording medium P is electrostatically adsorbed on the surface of the conveying belt 32 (surface having insulating properties).

The conveyor belt 32 is an endless belt, and is stretched in an elliptical shape by two belt rollers 34a and 34b. The conveying belt 32 is insulative on the front surface (outer surface) side on which the recording medium P is electrostatically attracted and conductive on the back surface (inner surface) side.
In addition, a flat plate-like conductive platen 36 is disposed inside the conveying belt 32 at a position facing the recording means 16.
The belt rollers 34a and 34b and the conductive platen 36 are both grounded, and therefore the back surface of the conveyor belt 32 is also installed via these.

  One of the belt rollers 34a and 34b is connected to a drive source (not shown) and is driven to rotate at a predetermined speed during recording. As a result, the conveyance belt 32 rotates clockwise in the drawing, and the recording medium P electrostatically attracted to the conveyance belt 32 is also conveyed in the same direction.

Further, the static elimination device 40 for the recording medium P includes a corotron static eliminator 52 and a high voltage power source 54. The neutralizing device 40 is disposed on the conveyance path of the recording medium P at a position between the recording unit 16 and the fixing roller pair 46 and facing the surface of the conveyance belt 32. One end of the high-voltage power supply 54 is connected to the corotron static eliminator 52, and the other end is grounded.
The corotron static eliminator 52 is covered with a hood 68 a connected to the duct 68. The duct 68 and the hood 68a will be described in detail later.
The recording medium P after recording is neutralized by a corotron neutralizer 52 connected to a high voltage power supply 54. Thereby, the recording medium P is easily separated from the transport belt 32.

The fixing roller pair 46, the switching claw 43, the reverse roller pair 47, and the guide 44a are arranged in this order on the downstream side of the static eliminator 40 on the conveyance path of the recording medium P.
The guide 44b and the transport roller 31b are arranged between the discharge tray 28 of the switching claw 43 on the transport path during transport, and the guide 44c and the transport roller 31c are on the transport path when the recording medium P is reversed. It is disposed between the conveying roller pair 47 and the charging device 38b.

  When double-sided recording is designated, the switching claw 43 is set to the reverse position after single-sided recording, and the recording medium P after single-sided recording is conveyed to the reverse roller pair 47 side. When the leading end of the recording medium P is nipped and conveyed by the reverse roller pair 47 and the leading end is placed on the guide 44a and the rear end is separated from the fixing roller pair 46, the trailing end is suspended on the guide 44c. At this timing, the reverse roller pair 47 is reversed, and the recording medium P is nipped and conveyed between the conveyance roller 31c and the guide 44c, and is supplied to a predetermined position on the conveyance belt 32 along the guide 44c.

  After recording when recording on only one side is specified, and after recording on both sides when recording on both sides is specified, the switching claw 43 is set to the discharge position, and the recording medium P after recording is supplied to the guide 44b side. Is done. Then, it is conveyed along the guide 44b by the fixing roller pair 46, and is further nipped and conveyed between the conveyance roller 31b and the guide 44b, discharged from the discharge unit, and sequentially stacked in the discharge tray 28 to be stocked. Is done.

The charging device 38b of the recording medium P has the same configuration as that of the charging device 38a, and the recording medium P is moved by the reversing roller pair 47 at a position downstream of the guide 44c on the conveyance path when the recording medium P is reversed. It is arranged at a position facing the surface of the conveyor belt 32 at a position after being conveyed.
Similarly to the above, the scorotron charger 48 of the charging device 38 b is covered with a hood 68 a connected to the duct 68. The duct 68 and the hood 68a will be described in detail later.

  The surface of the recording medium P supplied to a predetermined position on the conveying belt 32 along the guide 44c is charged by the charging device 38b, and the recording medium P is again electrostatically attracted onto the insulating surface of the conveying belt 32. Is done. Then, the recording medium P electrostatically adsorbed on the conveyor belt 32 is moved along with the movement of the conveyor belt 32, and is sandwiched and conveyed again between the conveyor roller 31a and the conveyor belt 32, and an image is recorded on the back side thereof. Is done.

Next, the recording unit 16 of the recording medium P will be described.
The recording means 16 records four colors on the recording medium P by electrostatic ink jet to record a full color image. The ink jet head 56, the head driver 58, the ink circulation system 60, and the recording medium. P position detection device 62.

The ink-jet head 56 is a line head capable of recording an image for one line at a time, and cyan (C), magenta (M), yellow (Y), and black (B) for recording a full-color image. Four color discharge heads are provided.
Specific examples of the discharge heads for the respective colors of the electrostatic ink jet head 56 that discharges the above-described color material particles (including the color material and charged fine particles) in a carrier liquid by electrostatic force. The head structure is shown in FIGS.

  FIG. 2 is a schematic partial perspective view showing a schematic configuration of an embodiment of each color ejection head 80 used in the inkjet head 56 shown in FIG. 3A is a schematic cross-sectional view showing a part of the ejection head 80 shown in FIG. 2, and FIG. 3B is a sectional view taken along the line IV-IV in FIG. . 4 (a), FIG. 4 (b) and FIG. 4 (c) are views taken along lines AA, BB and CC in FIG. 3 (b), respectively (excluding the through-hole portion). It is.

  The discharge head 80 shown in these drawings is an electrostatic ink jet having a control electrode having a two-layer electrode structure, and the ink Q containing charged particles such as a charged pigment (for example, fine particles such as toner) is statically discharged. The image is ejected by electric power and an image corresponding to the image data is recorded on the recording medium P. The head substrate 82, the ink guide 84, the insulating substrate 86, and the first control electrode 88 constituting the control electrode are recorded. And a second control electrode 90 and a floating conductive plate 92. The ejection head 80 is disposed so as to face the conveyance belt 32 that supports the recording medium P that becomes a counter electrode.

  In the ejection head 80 of the illustrated example, the control electrode has a two-layer electrode structure of a first control electrode 88 disposed on the upper surface and a second control electrode 90 disposed on the lower surface so as to sandwich the insulating substrate 86 therebetween. It is said.

  The discharge head 80 in the illustrated example further includes an insulating layer 94 a covering the lower side (lower surface) of the second control electrode 90, an insulating layer 94 b covering the upper side (upper surface) of the first control electrode 88, and the first control electrode 88. A sheet-like guard electrode 96 disposed above via the insulating layer 84 b and an insulating layer 94 c covering the upper surface of the guard electrode 96 are provided.

  In the illustrated ejection head 80, the ink guide 84 is made of an insulating resin flat plate having a projecting tip portion 84a and having a predetermined thickness, and is disposed on the head substrate 82 for each ejection portion. Further, a through hole 98 is opened at a position corresponding to the arrangement of the ink guide 84 in the laminated body of the insulating layer 94a, the insulating substrate 86, and the insulating layers 94b and 94c. The ink guide 84 is inserted into the through hole 98 from the insulating layer 94a side, and the tip end portion 84a of the ink guide 84 protrudes from the insulating layer 94c. In addition, in the leading end portion 84a of the ink guide 84, in order to promote the supply of the ink Q and the concentration of charged particles in the ink Q to the leading end portion 84a, a notch serving as an ink guide groove is formed in the vertical direction in the figure. You may do it.

  The leading end portion 84a of the ink guide 84 is formed into a substantially triangular shape (or trapezoid) that gradually becomes thinner toward the recording medium P (conveying belt 32). Further, it is preferable that a metal is vapor-deposited on the tip portion (the most advanced portion) 84a of the ink guide 84 from which the ink Q is discharged. Although the metal vapor deposition of the tip portion 84a of the ink guide 84 may not be performed, the metal vapor deposition substantially increases the dielectric constant of the tip portion 84a of the ink guide 84 and can easily generate a strong electric field. Therefore, it is preferable to perform metal deposition. The shape of the ink guide 84 is not particularly limited as long as the ink Q, in particular, the charged particles in the ink Q can be concentrated in the tip portion 84a through the through hole 98 of the insulating substrate 86. The tip portion 84a may be changed as appropriate, such as not having a protrusion, and may have a conventionally known shape.

  The head substrate 82 and the insulating layer 94a are disposed with a predetermined distance therebetween, and an ink flow path 100 that functions as an ink reservoir (ink chamber) for supplying the ink Q to the ink guide 84 is disposed between the head substrate 82 and the insulating layer 94a. Is formed. The ink Q in the ink flow path 100 includes charged particles charged with the same polarity as the voltages applied to the first control electrode 88 and the second control electrode 90, and during recording, the ink circulation system 60 (see FIG. 1). ) Is circulated at a predetermined speed (for example, an ink flow of 200 mm / s) from the right side to the left side (in the direction of arrow a in the figure) in the ink flow path 100 in the example shown in FIG. Hereinafter, the case where the charged particles in the ink are positively charged will be described as an example.

  As shown in FIG. 2, the first control electrode 88 and the second control electrode 90 surround the periphery of the through hole 98 opened in the insulating substrate 86, that is, the upper side of the insulating substrate 86 in the drawing, that is, the recording. On the surface on the medium P side, each discharge unit is arranged in a ring shape, that is, as a circular electrode. The electrode shapes of the first control electrode 88 and the second control electrode 90 are not limited to circular electrodes, and may be substantially circular, divided circular electrodes, parallel electrodes, or substantially parallel electrodes. good. The first control electrode 88 and the second control electrode 90 are configured in a two-layer electrode structure and are arranged in a matrix. Here, the plurality of first control electrodes 88 arranged in the row direction (for example, the main scanning direction) are connected to each other, and the plurality of second control electrodes 90 arranged in the column direction (for example, the sub-scanning direction) are Connected to each other.

  Here, one row of one control electrode 88 is set to a high voltage level or a floating (high impedance) state, one column of the second control electrode 90 is set to a high voltage level, and one row and one column are both set. By setting the ON state, it is possible to turn on one discharge portion where the two (row and column) intersect and to discharge ink from this discharge portion. At this time, ink is not ejected when one of the first and second control electrodes 88 and 90 is at the ground level. Thus, the first control electrode 88 and the second control electrode 90 arranged in a matrix can be driven in a matrix. Therefore, the number of head drivers 58 (see FIG. 1) for driving the first and second control electrodes 88 and 90 can be greatly reduced, the configuration of the head driver 58 can be made compact, and the mounting area thereof can be reduced. it can.

  On the other hand, at a position facing the ink guide 84, the recording medium P charged to a bias voltage having a polarity opposite to that of the charged charged particles in the ink is held by the conveyance belt 32 and disposed. As described above, in the present embodiment, the recording medium P is charged with a negative high voltage. The surface of the conveying belt 32 that holds the recording medium P is an insulating fluororesin surface, and the back surface is a conductive metal surface, which is grounded via a conductive belt roller 34b. (See FIG. 1).

  The floating conductive plate 92 is disposed below the ink flow path 100 and is in an electrically insulated state (high impedance state). In the illustrated example, it is arranged inside the head substrate 82.

  The floating conductive plate 92 generates an induced voltage in accordance with the voltage value applied to the ejection unit during image recording, and the charged particles are transferred to the insulating substrate in the ink Q in the ink flow path 100. It is intended to migrate to the 86 side and concentrate. Therefore, the floating conductive plate 92 needs to be disposed closer to the head substrate 82 than the ink flow path 100. Further, the floating conductive plate 92 is preferably arranged on the upstream side of the ink flow path 100 from the position of the ejection unit. Since the floating conductive plate 92 increases the concentration of charged particles in the upper layer in the ink flow path 100, the concentration of charged particles in the ink Q passing through the through hole 98 of the insulating substrate 86 can be increased to a predetermined concentration. Then, the concentration of the charged particles in the ink Q that is condensed to the tip portion 84a of the ink guide 84 and ejected as the ink droplet R can be stabilized at a predetermined concentration.

  In the ejection head 80 of the present embodiment having the control electrode having the two-layer electrode structure configured as described above, for example, a predetermined voltage, for example, 600 V is constantly applied to the second control electrode 90 to perform the first control. By switching the electrode 88 between a ground state (off state) and a high impedance state (on state) according to the image data, a pigment charged to the same polarity as the high voltage level applied to the second control electrode 90, etc. It is possible to control ejection / non-ejection of the ink Q (ink droplet R) containing the charged particles. That is, in the ejection head 80, when the first control electrode 88 is in the ground level (off state), the electric field strength in the vicinity of the leading end portion 84a of the ink guide 84 is low, and the ink Q jumps out of the leading end portion 84a of the ink guide 84. If the first control electrode 88 is in a high impedance state (ON state), the electric field strength in the vicinity of the tip portion 84a of the ink guide 84 increases, and the ink Q concentrated on the tip portion 84a of the ink guide 84 is caused by electrostatic force. Jump out from the tip 84a. At this time, further concentration can be performed by selecting conditions.

  In such a two-layer electrode structure, the first control electrode 88 can be switched between the high impedance state and the ground level, so that a large amount of power is not consumed for switching. Therefore, according to this embodiment, even in an inkjet head that requires high definition and high speed, power consumption can be significantly reduced.

  The first control electrode 88 may be switched between a ground level (off state) and a high voltage level (on state) in accordance with image data to control ejection / non-ejection. In the ejection head 80 of the present embodiment, ink is not ejected when one of the first control electrode 88 or the second control electrode 90 is at the ground level, and the first control electrode 88 is in a high impedance state or a high voltage level. Ink is ejected only when the second control electrode 90 is at a high voltage level.

  In the present embodiment, a pulse voltage may be applied to the first and second control electrodes 88 and 90 in accordance with an image signal, and ink ejection may be performed when both electrodes reach a high voltage level. .

  Note that it is not particularly limited whether the ink discharge / non-discharge control is performed by either or both of the first control electrode 88 and the second control electrode 90, but the first control electrode 88 or the second control electrode is not limited. When one of the electrodes 90 is at the ground level, the ink Q is not ejected, and only when the first control electrode 88 is in the high impedance state or the high voltage level and the second control electrode 90 is at the high voltage level, the ink Q is discharged. Should be discharged.

  Further, when the recording medium P is charged to, for example, -1.6 kV, and either one or both of the first control electrode 88 and the second control electrode 90 is a negative high voltage (for example, -600 V), ink is not ejected, Ink may be ejected only when both the first control electrode 88 and the second control electrode 90 are at the ground level (0 V).

  In addition, according to the present embodiment, since the ejection units are two-dimensionally arranged and matrix driven, a row driver that drives a plurality of ejection units in the row direction and a column driver that drives a plurality of ejection units in the column direction. The number can be greatly reduced. Therefore, according to the present embodiment, it is possible to significantly reduce the mounting area and power consumption of the drive circuit of the ejection units arranged two-dimensionally. In addition, according to the present embodiment, since the discharge portions can be arranged with a relatively large margin, the risk of discharge between the discharge portions can be extremely reduced, and high-density mounting and high voltage can be achieved. It is possible to achieve both safety.

  In the case of using the control electrode having the two-layer electrode structure composed of the first and second control electrodes 88 and 90 as in the electrostatic discharge type discharge head 80 described above, if the discharge portions are arranged at high density, they are adjacent to each other. Electric field interference may occur between the ejection parts. For this reason, it is preferable to provide the guard electrode 96 between the first control electrodes 88 of the adjacent ejection portions in order to shield the electric lines of force to the adjacent ink guide 84 as in the present embodiment.

  The guard electrode 96 is disposed between the first control electrodes 88 of the adjacent ejection units, and is for suppressing electric field interference that occurs between the ink guides 84 of the adjacent ejection units. 4 (a), (b) and (c) are views taken along the lines AA, BB and CC in FIG. 3 (b), respectively. As shown in FIG. 4A, the guard electrode 96 is a sheet-like electrode such as a metal plate that is common to all the discharge portions, and is around the through-hole 98 for each discharge portion that is two-dimensionally arranged. A portion corresponding to the first control electrode 88 formed in is drilled (see FIG. 3). In the present embodiment, the reason why the guard electrodes 96 are provided is that when the discharge portions are arranged at a high density, the electric field generated by the discharge portion of its own is affected by the state of the electric field of the adjacent discharge portions, and the dot size and This is because the dot drawing position is disturbed, which may adversely affect the recording quality.

  By the way, the upper side of the guard electrode 96 in the figure is covered with an insulating layer 94 c except for the through hole 98, and an insulating layer 94 b is interposed between the guard electrode 96 and the first control electrode 88. And 88 are insulated. That is, the guard electrode 96 is disposed between the insulating layer 94c and the insulating layer 94b, and the first control electrode 88 is disposed between the insulating layer 94b and the insulating substrate 86.

  That is, as shown in FIG. 4B, the insulating substrate 86 is formed on the upper surface, and therefore between the insulating layer 94b and the insulating substrate 86, around the through hole 98 for each discharge portion. The first control electrodes 88 are two-dimensionally arranged, and a plurality of first control electrodes 88 in the column direction are connected to each other.

  Further, as shown in FIG. 4C, on the upper surface of the insulating layer 94a, and therefore on the lower surface of the insulating substrate 86, that is, between the insulating layer 94a and the insulating substrate 86 (see FIG. 3). ), The second control electrodes 90 formed around the through-holes 98 of the respective discharge units are two-dimensionally arranged, and a plurality of second control electrodes 90 in the row direction are connected to each other.

  Further, in the present embodiment, the first and second control electrodes 88 are used to shield the repulsive electric field in the direction of the ink flow path 100 from the control electrodes of each ejection unit, for example, the first and second control electrodes 88 and 90. Further, shield electrodes may be provided on the 90 flow path side.

Further, in the ejection head 80 according to the present embodiment, the ink flow path 100 is configured to form the bottom surface of the ink flow path 100, and the induced voltage that is constantly generated by the pulse voltage applied to the first control electrode 88 and the second control electrode 90 causes There is provided a floating conductive plate 92 that causes positively charged charged particles (charged colored particles) in the flow channel 100 to migrate upward (that is, toward the recording medium P). In addition, a coating film (not shown) that is electrically insulating is formed on the surface of the floating conductive plate 92 to prevent the physical properties and components of the ink from becoming unstable due to charge injection into the ink. To do. The electrical resistance of the insulating coating film is preferably 10 ¹² Ω · cm or more, more preferably 10 ¹³ Ω · cm or more. In addition, the insulating coating film is desirably resistant to corrosion with respect to the ink, thereby preventing the floating conductive plate 92 from being corroded by the ink. In addition, the floating conductive plate 92 is covered with an insulating member from below. With such a configuration, the floating conductive plate 92 is completely electrically insulated and floated.

  There is one or more floating conductive plates 92 per unit of discharge heads (for example, when there are four discharge heads C, M, Y, and K, the number of floating conductive plates is at least one each, A common floating conductive plate is not used between the discharge head units of C and M).

  In the above-described embodiment, as the first and second control electrodes 88 and 90, circular electrodes and the like are provided for each discharge unit and connected in the row and column directions, respectively, but the present invention is not limited to this, All of the discharge parts may be driven independently, or one of the first and second control electrodes 88 and 90 may be a sheet-like electrode common to all of the discharge parts (the through hole 98 portion is perforated). Is good).

  In the above embodiment, the control electrode has a two-layer electrode structure of the first and second control electrodes 88 and 90. However, the present invention is not limited to this, and may be a control electrode having a single-layer electrode structure. The single layer control electrode may be disposed on either surface of the insulating substrate 86, but is preferably provided on the recording medium P side. The ejection heads for the respective colors are configured as described above, for example.

  The respective ejection heads are arranged so that the arrangement direction of the ejection portions thereof coincides with the direction orthogonal to the conveyance direction of the recording medium P, and the ejection heads of the respective colors are arranged in a line along the conveyance direction of the recording medium P. ing. In addition, each ejection head is electrostatically adsorbed and transported on the transport belt 32 at a position where the ink ejection section faces the surface of the transport belt 32 where the conductive platen 36 is disposed. The recording medium P is arranged so as to be at a predetermined constant interval from the surface of the recording medium P. Further, the arrangement direction of the ejection units of the respective ejection heads may be arranged substantially in parallel with the conveyance direction of the recording medium P. In this case, ejection is performed while the ejection head performs main scanning in a direction orthogonal to the conveyance direction of the recording medium P, and then serial scanning is repeated in which the recording medium P is conveyed by a certain amount.

  As described above, the surface of the recording medium P electrostatically adsorbed on the conveying belt 32 serving as the counter electrode is uniformly charged to a predetermined negative high potential by the charging device 38 of the recording medium P, and always has a constant DC. In this state, a bias voltage (about -1.5 kV) is applied. In addition, a pulse voltage corresponding to image data is applied to the control electrode of the ejection portion of each color ejection head during recording by a pulse voltage application device (not shown) for applying an inkjet head 56 to be described later.

  In each color ejection head, when a high voltage (400 to 600 V) is applied as a pulse voltage while a constant DC bias voltage (about −1.5 kV) is applied to the recording medium P, the ink is discharged. When ejection is performed and a low voltage (0 V) is applied, ink ejection is not performed. The ink ejected from each color ejection head is pulled and landed on the recording medium P charged with a bias voltage, and a full-color image corresponding to the image data is recorded.

  In this way, by charging the recording medium P with a bias voltage (opposite polarity to the color material particles), the positively charged color material particles in the ink are attracted from the ejection holes toward the tip of the ink guide. The charged particles are efficiently concentrated at the tip portion of the ink guide. When a pulse voltage is applied to the control electrode, the charged particles are further concentrated at the tip portion of the ink guide and ejected as ink droplets.

  In the present embodiment, a constant DC bias voltage is always applied to the surface of the recording medium P electrostatically adsorbed on the conveying belt 32 serving as a counter electrode, and the control electrode is subjected to image data during recording. Although the pulse voltage is applied, the counter electrode side is grounded, and a constant DC bias voltage is always applied to the control electrode side of the ejection portion of the ejection head of each color by the DC bias voltage application device for application of the inkjet head 56 described later. (For example, 1.5 kV) may be applied.

As described above, the ink (ink Q) used in the present invention is obtained by dispersing coloring material particles (including coloring material and charged fine particles) in a carrier liquid (ink composition).
In addition to the colorant particles, dispersed ink particles for improving the fixability of an image after printing may be appropriately contained in the ink.

The carrier liquid is preferably a dielectric liquid (nonaqueous solvent) having a high electric resistivity (10 ⁹ Ω · cm or more, preferably 10 ¹⁰ Ω · cm or more). When the electric resistance of the carrier liquid having a low electric resistivity is low, the carrier liquid itself is charged by charge injection due to the voltage applied by the control electrode, so that the coloring material particles do not concentrate. In addition, a carrier liquid having a low electrical resistivity is not suitable for the present invention because there is a concern of causing electrical conduction between adjacent control electrodes.

The relative dielectric constant of the dielectric liquid used as the carrier liquid is preferably 5 or less, more preferably 4 or less, and still more preferably 3.5 or less. By setting the relative dielectric constant in such a range, an electric field effectively acts on the colorant particles in the carrier liquid, and migration easily occurs.
Note that the upper limit value of the specific electric resistance of such a dielectric liquid is preferably about 10 ¹⁶ Ωcm, and the lower limit value of the relative dielectric constant is preferably about 1.9. The reason why it is desirable that the electric resistance of the dielectric liquid is in the above range is that if the electric resistance is low, ink ejection under a low electric field is deteriorated, and that the relative dielectric constant is preferably in the above range. This is because when the dielectric constant increases, the electric field is relaxed by the polarization of the solvent, and the color of the dots formed thereby becomes light or causes blurring.

  The dielectric liquid used as the carrier liquid is preferably a linear or branched aliphatic hydrocarbon, alicyclic hydrocarbon, or aromatic hydrocarbon, and halogen-substituted products of these hydrocarbons. For example, hexane, heptane, octane, isooctane, decane, isodecane, decalin, nonane, dodecane, isododecane, cyclohexane, cyclooctane, cyclodecane, benzene, toluene, xylene, mesitylene, Isopar C, Isopar E, Isopar G, Isopar H, Isopar L, Isopar M (isopar: trade name of Exxon), Shellsol 70, Shellsol 71 (shellsol: trade name of Shell Oil), Amsco OMS, Amsco 460 solvent (trade name of Amsco: Spirits), Silicone oil (for example, KF-96L manufactured by Shin-Etsu Silicone) or the like can be used alone or in combination.

The color material particles dispersed in such a carrier liquid may be dispersed in the carrier liquid as the color material itself as the color material particles, or may be contained in the dispersed resin particles for improving the fixability. When contained in the dispersed resin particles, the pigment is generally coated with the resin material of the dispersed resin particles to obtain resin-coated particles, and the dye is a colored particle by dispersing the dispersed resin particles. Etc. are common.
As the color material, any pigments and dyes that have been conventionally used in inkjet ink compositions, printing (oil-based) ink compositions, or electrophotographic liquid developers can be used.

  In the ink, the content of the color material particles (the total content of the color material particles or further dispersed resin particles) is preferably contained in the range of 0.5 to 30% by weight with respect to the whole ink, and more preferably. It is desirable to contain in the range of 1.5 to 25% by weight, more preferably 3 to 20% by weight. If the content of the color material particles is reduced, problems such as insufficient printed image density and difficulty in obtaining a strong image due to difficulty in obtaining the affinity between the ink and the surface of the recording medium P are likely to occur. On the other hand, when the content is increased, it becomes difficult to obtain a uniform dispersion liquid, or ink clogging in the inkjet head 10 or the like is likely to occur, and it is difficult to obtain stable ink ejection.

As the pigment used as the color material, regardless of inorganic pigments or organic pigments, those generally used in the technical field of printing can be used. Specifically, for example, carbon black, cadmium red, molybdenum red, chrome yellow, cadmium yellow, titanium yellow, chromium oxide, viridian, cobalt green, ultramarine blue, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment Conventionally known pigments such as quinacridone pigments, isoindolinone pigments, dioxazine pigments, selenium pigments, perylene pigments, perinone pigments, thioindigo pigments, quinophthalone pigments, metal complex pigments, and the like are not particularly limited. Can be used.
As dyes used as coloring materials, azo dyes, metal complex dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinoneimine dyes, xanthene dyes, aniline dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes And oil-soluble dyes such as phthalocyanine dyes and metal phthalocyanine dyes.

  The average particle diameter of the colorant particles dispersed in the carrier liquid is preferably 0.1 to 5 μm, more preferably 0.2 to 1.5 μm, and still more preferably 0.4 to 1.0 μm. . This particle size is determined by CAPA-500 (trade name, manufactured by Horiba, Ltd.).

After the color material particles are dispersed in the carrier liquid, the charge material is added to the carrier liquid to charge the color material particles, thereby obtaining an ink in which the charged color material particles are dispersed in the carrier liquid. In addition, you may add a dispersion medium as needed at the time of dispersion | distribution of colored fine particles.
As an example of the charge control agent, various materials used in electrophotographic liquid developers can be used. Also, “Recent development and commercialization of electrophotographic development systems and toner materials”, pages 139 to 148, “The Basics and Applications of Electrophotographic Technology” edited by Electrophotographic Society, pages 497 to 505 (Corona Inc., published in 1988), Yuji Harasaki Various charge control agents described in “Electrophotography” 16 (No. 2), p. 44 (1977) can also be used.

The color material particles may be positively charged or negatively charged as long as they have the same polarity as the drive voltage applied to the control electrode.
The charge amount of the color material particles is preferably in the range of 5 to 200 μC / g, more preferably 10 to 150 μC / g, and still more preferably 15 to 100 μC / g.

In addition, since the electric resistance of the dielectric solvent may change due to the addition of the charge control agent, the distribution ratio P defined below is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. And
P = 100 × (σ1−σ2) / σ1
Here, σ1 is the electrical conductivity of the ink, and σ2 is the electrical conductivity of the supernatant obtained by applying the ink to the centrifuge. The electrical conductivity was measured using an LCR meter (AG-4311 manufactured by Ando Electric Co., Ltd.) and an electrode for liquid (LP-05 type manufactured by Kawaguchi Electric Manufacturing Co., Ltd.) under the conditions of an applied voltage of 5 V and a frequency of 1 kHz. This is the measured value. Centrifugation was performed for 30 minutes using a small high-speed cooling centrifuge (Tomy Seiko Co., Ltd. SRX-201) under conditions of a rotational speed of 14500 rpm and a temperature of 23 ° C.
By using the ink as described above, migration of the color material particles is likely to occur and it is easy to concentrate.

The electric conductivity of the ink is preferably 100 to 3000 pS / cm, more preferably 150 to 2500 pS / cm, and still more preferably 200 to 2000 pS / cm. By setting the electric conductivity in the above range, the voltage applied to the control electrode does not become extremely high, and there is no fear of causing electrical continuity between adjacent recording electrodes.
The surface tension of the ink is preferably in the range of 15 to 50 mN / m, more preferably 15.5 to 45 mN / m, still more preferably 16 to 40 mN / m. By setting the surface tension within this range, the voltage applied to the control electrode does not become extremely high, and the ink does not leak around the head to be contaminated.
Furthermore, the viscosity of the ink is preferably 0.5 to 5 mPa · sec, more preferably 0.6 to 3.0 mPa · sec, and still more preferably 0.7 to 2.0 mPa · sec.

In the present invention, it is a solid component mainly dispersed in a carrier liquid, rather than causing the ink to fly toward the recording medium by applying a force to the entire ink as in the conventional ink jet system. A force is applied to the color material particles to fly.
As a result, images can be recorded on various recording media P such as plain paper and non-absorbing films (for example, PET film), and bleeding and flow are generated on the recording media P. Therefore, high-quality images can be obtained on various recording media.

Such ink is supplied to the inkjet head 56 by the ink circulation system 60.
The ink circulation system 60 includes an ink tank 64, a pump (not shown), and an ink supply path and a recovery path 66. The ink tank 66 is disposed on the bottom surface inside the housing 22, and is connected to the inkjet head 56 via an ink supply path and a recovery path 66.

  In the ink tank 64, four colors of ink including color material particles of each color and a dispersion solvent for dispersing the color material particles are held. The ink of each color in the ink tank 64 is supplied by a pump to the discharge head of each color of the inkjet head 56 via the ink supply path 66. Further, the extra ink of each color that has not been used for image recording is collected by the pump into the ink tank 64 of each color via the ink collection path 66.

  The position detection device 62 of the recording medium P is a conventionally known position detection means such as a photosensor, and the recording medium P is located at a position between the charging device 38 and the inkjet head 56 on the conveyance path of the recording medium P. It is arrange | positioned in the position facing the surface of the conveyance belt 32 conveyed.

  The position of the recording medium P is detected by the position detection device 62, and the position information is supplied to the head driver 58.

  The head driver 58 is attached to the right side in the figure inside the housing 22 and is connected to the inkjet head 56.

  Image data is input to the head driver 58 from an external device, and position information of the recording medium P is input from the position detection device 62. Under the control of the head driver 58, the ejection timing of each color ejection head of the inkjet head 56 is controlled according to the position information of the recording medium P, and each color ink is ejected from each color ejection head according to the image data. On P, a full color image corresponding to the image data is recorded.

  That is, the recording medium P is transported in front of the inkjet head 56 by the transport unit 14 at a predetermined constant speed, and the recording unit 16 performs four-color printing on the surface to record a full color image.

Subsequently, the solvent recovery means 18 will be described.
The solvent recovery means 18 is disposed on the center of the bottom surface inside the housing 22 and is a dispersion solvent that evaporates from the ink ejected from the inkjet head 56 onto the recording medium P, a dispersion solvent that evaporates from the ink when fixing an image, or the like. Although not shown in the figure, an activated carbon filter, a discharge fan, a cooling device, and the like are provided.
The air containing the dispersed solvent component inside the housing 22 is cooled by the cooling device, the solvent component is condensed, and is discharged outside the housing 22 through the activated carbon filter. At that time, the solvent component aggregated by the cooling device is reused or stored in a waste liquid tank (not shown).

  Further, the air containing the dispersed solvent component inside the housing 22 is discharged to the outside of the housing 22 through an activated carbon filter (not shown) by a discharge fan (not shown). At that time, the dispersion solvent component contained in the air inside the housing 22 is adsorbed and removed by the activated carbon filter.

  By the way, as will be described in detail later, in the recording apparatus 10, the recording medium P is conveyed by the conveying belt 32 of the conveying means 14, and the bias voltage is charged by the charging device 38a (and the recording medium P is thereby conveyed). Then, the image is recorded by electrostatic ink jet by the recording means 16, the charge is removed by the charge removing means 40, the recording medium P is peeled from the transport belt 32, and is discharged to the discharge tray 28. . When image recording is performed on both sides, after recording on one side, the recording medium P is inverted by the action of a switching claw and the like, and the bias voltage is charged by the charging means 38b. Static elimination and discharge to the discharge tray 28 are performed.

In a normal electrostatic ink jet, a high voltage of about several kV is necessary to eject ink droplets. By charging the recording medium P with a bias voltage in this way, about several hundred volts is used. It is possible to perform ejection even with a driving voltage. In addition, the bias voltage acts to attract the charged particles toward the tip of the ink guide, and the charged particles are efficiently concentrated at the tip of the ink guide. Is possible. Furthermore, since the ink is always concentrated, the responsiveness to the pulse voltage is improved, so that high frequency recording is possible.
However, in the electrostatic ink jet that applies a bias voltage to the recording medium P as described above, the concentration of the color material particles may become unstable or the discharge state may become unstable. In the case of recording, there is a problem that this tendency becomes remarkable.

  As a result of intensive studies on this point, the present inventor has found that when applying a bias voltage to the storage medium P or further removing the charge from the recording medium P, the charging device such as the scorotron charger 48 and the corotron discharger 52 or the charge removal It was found that the ozone generated from the apparatus comes into contact with the ink and the ink is denatured, which causes the concentration of the color material particles to become unstable and the discharge state to become unstable.

Here, in the recording apparatus 10, a region where ink and ozone may come into contact is in the vicinity of the inkjet head 56, specifically, the inkjet head 56 (each ejection head 80), This is a gap with the recording medium P.
Therefore, in the present invention, ozone is removed from the vicinity of the inkjet head when the scorotron charger 48 charges the recording medium P with a bias voltage, or further, ozone generated when the corotron neutralizer 52 neutralizes the recording medium P. An ozone removing means 20 is arranged for this purpose.

Hereinafter, the ozone removing means 20 will be described in detail.
The ozone removing unit 20 includes a duct 68, an exhaust fan 70, an ozone treatment filter 72, and a residual heat supply unit 76.
The duct 68 has a main pipe and three branch pipes, and the front ends of the branch pipes are located in the vicinity of the scorotron charger 48 of the charging devices 38 a and 38 b and the corotron static remover 52 of the static elimination device 40, respectively. The hood 68a is provided at the tip thereof so as to cover the scorotron charger 48 and the corotron static eliminator 52. Further, an exhaust fan 70 for exhausting air to the outside of the apparatus is installed on the base end (reverse end of the branch pipe) side of the main pipe of the duct 68.

  Accordingly, by driving the exhaust fan 70, the ozone generated from the scorotron charger 48 and the corotron static eliminator 52 can be sucked from the hood 68a and discharged to the outside of the apparatus through the duct 68, that is, the scorotron charger 48 and the The ozone generated from the corotron static eliminator 52 does not reach the vicinity of the inkjet head 56, that is, can be removed from the vicinity of the inkjet head 56. And since ozone is discharged | emitted outside, deterioration of the rubber components etc. in an apparatus by ozone can be reduced, and lifetime can also be attained.

In the present invention, the ozone removing means may be always driven in the present invention, but preferably, at least one of them is driven in synchronism with the driving of the scorotron charger 48 and the corotron static eliminator 52. It is preferable to drive only when
Therefore, in the illustrated example, the exhaust fan 70 may be driven at all times. However, preferably, the exhaust fan 70 is driven only when at least one is driven in synchronization with the driving of the scorotron charger 48 and the corotron static eliminator 52. Is preferred.

In the illustrated example, as a preferred embodiment, an ozone treatment filter 72 that treats ozone in the exhaust by the exhaust fan 70 is disposed between the exhaust fan 70 and the housing 22. By having such an ozone treatment filter 72, contamination of the installation environment of the recording apparatus 10 due to ozone can be prevented.
The ozone treatment filter 72 is used for removing ozone such as ozone adsorption means such as activated carbon, a catalyst for treating ozone such as manganese, lead, chromium, cobalt, nickel, or other metal oxides or composites. What is necessary is just to comprise using a well-known means. Moreover, it is preferable that the ozone treatment filter 72 (ozone treatment means) is a cartridge type so that it can be easily replaced.

Furthermore, in the illustrated example, as a preferred embodiment, a residual heat supply means 76 is provided.
The residual heat supply means 76 is means for supplying heat to the ozone treatment filter 72, and includes a duct 74 and a residual heat supply valve 78.
One end of the duct 74 is disposed in the vicinity of the fixing roller pair 46 that heats and fixes the image of the recording medium P after recording, and the other end is connected to the ozone processing filter 72.
The duct 74 transmits the residual heat generated when the fixing roller pair 46 heats and fixes the recording medium P, and the ozone treatment filter 72 is heated by the heat. Thereby, the ozone treatment filter 72 deteriorated by the treatment of ozone can be recovered, and the predetermined ozone absorption efficiency can be maintained. In addition, by using the fixing roller pair 46, a new heat source is unnecessary and energy saving can be achieved.

Here, the recovery of the ozone treatment filter 72 is more efficient when it is performed when ozone treatment is not performed, that is, when recording is not performed.
Correspondingly, the remaining heat supply means 76 in the illustrated example has a remaining heat supply valve 78 in the middle of the duct 74, and the remaining heat supply valve 78 is closed during operation of the exhaust fan 70 (during image recording). The ozone treatment filter 72 is not restored, and when the exhaust fan 70 is stopped, the residual heat supply valve 78 is opened to restore the ozone treatment filter 72. As a result, the ozone treatment filter 72 can be recovered more efficiently, and the ozone absorption efficiency can be more suitably maintained.

In the present invention, the heating of the ozone treatment filter 72 is not limited to using the residual heat of the heat source that the recording apparatus 10 such as the fixing roller pair 46 basically has. For example, the vicinity of the ozone treatment filter 72 or the like. In addition, a heating means may be provided separately.
The arrangement of the exhaust fan 70 and the ozone treatment filter 72 is not particularly limited, and may be arranged at any position of the duct 68.

In the ozone removing means 20 in the illustrated example, both the ozone treatment filter 72 and the residual heat supply means 76 are arranged as a preferred mode.
Therefore, in the illustrated example, the ozone removing means 20 may be constituted by only the duct 68 and the exhaust fan 70, or may be constituted by having the ozone treatment filter 72 or the residual heat supply means 76 therein.

Hereinafter, the operation of the recording apparatus 10 will be described.
In the recording apparatus 10, when the image is recorded, the recording medium P stored in the paper feed tray 24 is taken out one by one by the feed roller 26, and is sandwiched between the conveyance roller 31 a and the conveyance belt 32, and the conveyance belt 32. It is conveyed to a predetermined position above.

  The recording medium P transported to a predetermined position on the transport belt 32 is charged with a bias voltage at a negative high potential by the charging device 38 a and is electrostatically attracted to the surface of the transport belt 32.

  The recording medium P electrostatically attracted to the surface of the transport belt 32 is moved at a predetermined constant speed as the transport belt 32 is moved, and an image corresponding to the image data is recorded on the surface of the recording medium P by the ink jet head 56.

  The recording medium P after single-sided recording is neutralized by the neutralization device 40 and is nipped and conveyed by the fixing roller pair 46, while the recorded image is heated and fixed.

  When recording on only one side is designated, the recording medium P after single-sided recording is transported along the guide 44b by the fixing roller pair 46 in accordance with the switching claw 43 set at the discharge position, and further the transport roller 31b and the guide 44b are nipped and conveyed, discharged from the discharge section, stacked in the discharge tray 28 and stocked.

  On the other hand, when double-sided recording is designated, the recording medium P after single-sided recording is conveyed to the reverse roller pair 47 side by the fixing roller pair 46 according to the switching claw 43 set at the reverse position. The Thereafter, the reversing roller pair 47 is reversed, and the recording medium P is conveyed along the guide 44c, further sandwiched and conveyed between the conveying roller 31c and the guide 44c, and supplied to a predetermined position on the conveying belt 32. The That is, the recording medium P is inverted at this stage.

  Thereafter, the reversed recording medium P is moved along with the movement of the conveying belt 32, and similarly, an image corresponding to the image data is recorded on the back surface thereof. The subsequent operation is the same as when recording on only one side is designated.

In synchronism with the above recording operation, the ozone removing means 20 drives the exhaust fan 70 to suck ozone generated by the charging means 48 and the charge removing means 52. The sucked ozone is processed by passing through the ozone treatment filter 72, and the exhaust is discharged to the outside of the housing 22. During recording, the residual heat supply valve 78 is basically closed.
Therefore, since ozone can be removed from the vicinity of the inkjet head 56, the ink is not deteriorated by ozone, and even when continuous recording is performed at high speed, the concentration of charged particles and the ejection state can be stabilized. High-quality image recording can be performed with high productivity.

  In a state where recording is not performed, the residual heat supply valve 78 is opened, and the heat of the fixing roller 46 is transmitted to the ozone removal filter 72 by the duct 74 and heated to recover the ozone removal filter 72. If necessary, the fixing roller pair 46 may be heated to recover the ozone removal filter 72.

  Next, the ink jet recording apparatus of the present invention will be described with reference to another embodiment.

  FIG. 5 is a schematic configuration diagram of a second embodiment of the electrostatic ink jet recording apparatus of the present invention. The electrostatic ink jet recording apparatus 110 shown in the figure has the same configuration as the recording apparatus 10 shown in FIG. Accordingly, the same reference numerals are given to the same constituent elements in both, and detailed description thereof will be omitted. Hereinafter, points specific to the ink jet recording apparatus 110 will be mainly described.

The ozone removing unit 120 of the inkjet recording apparatus 110 includes a duct 122, a blower 124, an ozone treatment filter 126, and a residual heat supply unit 128.
The duct 122 has a proximal end portion that penetrates the housing 22 and protrudes outside the housing 22. Further, a hood 112 is disposed at the tip of the duct 122 so as to cover the inkjet head 56. In the middle of the duct 122, the outside air of the apparatus is blown to the hood 112 through the duct 122.

Therefore, by driving the blower 124, the air that does not contain ozone outside the apparatus can be supplied to the vicinity of the inkjet head 56, and the ozone generated from the scorotron charger 48 and the corotron static eliminator 52 as in the previous example. Can be removed from the vicinity of the inkjet head 56.
As a result, even when continuous recording is performed at a high speed without causing ink deterioration due to ozone, charged particles can be concentrated and the ejection state can be stabilized, and high-quality image recording can be performed with high productivity. be able to.

In the illustrated example, as a preferred embodiment, an ozone treatment filter 126 is disposed inside the exhaust port (upper right in the figure) for discharging the air in the housing 22.
As a result, ozone can be removed from the air exhausted to the outside by the blow of outside air to the vicinity of the inkjet head 56 by driving the blower 124, so that the installation of the apparatus can be performed as in the previous example. Prevents environmental pollution. In addition, what is necessary is just to utilize the thing similar to the ozone treatment filter 126 previously.

As a preferred embodiment, the ozone treatment filter 126 is provided with a residual heat supply means 128.
The residual heat supply means 128 includes a duct 130 and a residual heat supply valve 132. One end of the duct 128 is connected to the ozone removal filter 126, and the other end is disposed in the vicinity of the fixing roller 46. .
In this residual heat supply means 128, similar to the residual heat supply means 76 of the recording apparatus 10 shown in FIG. 1, the duct 130 transmits the residual heat generated by the fixing roller pair 46, and the ozone removal filter 72 is heated / recovered by the heat. Is. Similarly, the residual heat supply valve 132 is not recovered during recording but is opened / closed / closed to recover during non-recording.

As described above, in the present embodiment, the ozone treatment filter 126 and the residual heat supply means 128 are provided as a preferred mode. Therefore, the ozone removing means 120 may be constituted by only the duct 122 and the blower 124, or may be constituted by adding only the ozone treatment filter 126 thereto.
Furthermore, also in this embodiment, the heating means of the ozone treatment filter 126 is not limited to the residual heat supply, and any heating means may be provided.

  FIG. 6 is a schematic configuration diagram of a third embodiment of the electrostatic ink jet recording apparatus of the present invention. The electrostatic ink jet recording apparatus 160 shown in the figure also has the same configuration as the recording apparatus 10 shown in FIG. Accordingly, the same reference numerals are given to the same constituent elements in both, and detailed description thereof will be omitted. Hereinafter, points unique to the ink jet recording apparatus 160 will be described mainly.

The ozone removing unit 170 of the ink jet recording apparatus 160 includes an ozone processing filter 172.
The ozone treatment filter 172 is disposed in contact with the scorotron charger 48 of the charging units 38 a and 38 b and the corotron charger 52 of the charge removing unit 40. Note that the ozone treatment filter 172 may be the same as the ozone removal filter 72 shown in FIG.

Since the ozone treatment filter 172 is disposed in contact with the scorotron charger 48 and the corotron static eliminator 52, the ozone generated in the scorotron charger 48 and the corotron static eliminator 52 is treated by the ozone treatment filter 172. The
Therefore, as in the previous examples, the ozone generated from the scorotron charger 48 and the corotron static eliminator 52 does not reach the vicinity of the inkjet head 56, that is, it can be removed from the vicinity of the inkjet head 56. Therefore, even when continuous recording is performed at high speed, the charged particles can be concentrated and the ejection state can be stabilized, and high-quality image recording can be performed with high productivity. Moreover, in this example, since ozone is processed, contamination of the installation environment of the apparatus can be prevented as in the previous example.

The present invention is not limited to the ink jet recording apparatuses 10, 110, and 160 shown in FIGS. 1, 5, and 6, and can be applied to various conventionally known electrostatic ink jet recording apparatuses. . That is, specific examples of the holding means 12, the conveying means 14 and the recording means 16, the solvent recovery means 18, and the ozone removing means 20, 120 and 170 of the recording medium P constituting the electrostatic ink jet recording apparatus to which the present invention is applied. The configuration is not limited to that of the illustrated example.
Moreover, in the said Example, although the inkjet recording device which records on both surfaces was shown, it is not limited to this, The inkjet recording device which records on one side may be sufficient.

The present invention is basically as described above.
Although the electrostatic ink jet recording apparatus of the present invention has been described in detail, the present invention is not limited to the above-described embodiment, and various modifications and changes may be made without departing from the spirit of the present invention. It is.

1 is a schematic configuration diagram of a first embodiment of an electrostatic ink jet recording apparatus of the present invention. It is a typical fragmentary perspective view which shows schematic structure of one Embodiment of the discharge head of each color currently used with the inkjet head shown in FIG. (A) is typical sectional drawing which shows a part of discharge head shown in FIG. 2, (b) is the IV-IV sectional view taken on the line of Fig.2 (a). (A), (b), and (c) are the AA, BB, and CC line arrow views of FIG.3 (b), respectively. It is the structure schematic of 2nd Embodiment of the electrostatic inkjet recording device of this invention. It is the structure schematic of 3rd Embodiment of the electrostatic inkjet recording device of this invention.

Explanation of symbols

10, 110, 160 Electrostatic ink jet recording apparatus 12 Holding means 14 Conveying means 16 Recording means 18 Solvent recovery means 20, 120, 170 Ozone removing means 22 Case 24 Paper feed tray 26 Feed roller 28 Discharge tray 30 Conveying roller pair 31a , 31b, 31c Conveying roller 32 Conveying belt 34a, 34b, 34c Belt roller 36 Conductive platen 38 Charging device 40 Neutralizing device 42 Separation claw 44, 44a, 44b Guide 46 Fixing roller pair 48 Scorotron charger 50, 54 High voltage power supply 52 Corotron Static eliminator 56 Inkjet head 58 Head driver 60 Ink circulation system 62 Position detection device 64 Ink tank 66 Ink supply path and recovery path 68, 76, 122, 130 Duct 70 Exhaust fan 72, 126, 172 Zon processing filter 74, 128 Residual heat supply means 78, 132 Residual heat supply valve 80 Discharge head 82 Head substrate 84 Ink guide 84a Ink guide tip 86 Insulating substrate 88, 90 Control electrode 92 Floating conductive plate 94a, 94b, 94c Insulating layer 96 Guard electrode 98 Through hole 100 Ink flow path 124 Blower

Claims (10)

An inkjet head that discharges ink onto a recording medium by applying an electrostatic force to ink containing charged particles;
Charging means for charging the recording medium;
An ink jet recording apparatus comprising: ozone removing means for removing ozone in the vicinity of the ink jet head inside the apparatus.   The inkjet recording apparatus according to claim 1, further comprising a discharging unit that discharges the recording medium after image recording.   3. The ink jet recording apparatus according to claim 1, wherein the ozone removing unit is driven in synchronism with the charging unit or further the charge eliminating unit.   4. The ink jet recording apparatus according to claim 1, wherein the ozone removing unit is an exhaust unit that exhausts air from the vicinity of the charging unit or further from the neutralizing unit.   The inkjet recording apparatus according to claim 4, wherein the exhaust unit includes an ozone treatment unit in an exhaust path.   The inkjet recording apparatus according to claim 1, wherein the ozone removing unit is a blowing unit that blows gas outside the apparatus to the vicinity of the inkjet head.   The ink jet recording apparatus according to claim 6, further comprising an ozone treatment unit in an exhaust portion to the outside of the apparatus.   The ink jet recording apparatus according to claim 1, wherein the ozone removing unit is an ozone processing unit disposed in the vicinity of the charging unit or further the neutralizing unit.   9. The ink jet recording apparatus according to claim 5, further comprising a heating unit that heats the ozone treatment unit.   The image forming apparatus further includes a heat fixing unit that heat-fixes an image after image recording by the ink jet head, and the heating unit is a unit that transmits heat generated by the heat fixing unit to the ozone processing unit. The ink jet recording apparatus according to claim 9.

Images