JP2007176045A - Liquid drop discharging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress moving of a conveyor belt to a side of a liquid drop discharging head, without increasing electromagnetic interference and a damage to the conveyor belt. <P>SOLUTION: A platen 48 is arranged facing a recording head 32 with the transfer belt 28 interposed therebetween. The conveyor belt 28 is composed of two layers of a dielectric layer 28A and a conductive layer 28B, in which a plurality of through holes H arranged at least in one direction, either in the peripheral direction or in the width direction are formed in the conductive layer 28B, exposing the dielectric layer 28A from the through hole H. The portion exposing from the through hole H of the dielectric layer 28A is rubbed on the platen 48 to generate friction charge, generating electrostatic attractive force between the conveyor belt 28 and the platen 48. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a droplet discharge device that includes a droplet discharge head that discharges droplets and a conveyance belt that holds a recording medium and conveys the recording medium to face the droplet discharge head.

  In an ink jet printer as a droplet discharge device, a charging member is used to charge a conveying member such as a conveying belt or a conveying drum, thereby generating an electrostatic adsorption force between the recording medium and the conveying member. To be electrostatically adsorbed. In this state, the recording medium is passed through the ink droplet ejection area of the recording head (droplet ejection head) to record an image on the recording medium. As a result, the uniformity of the distance between the recording medium and the nozzle surface of the recording head (hereinafter referred to as TD: Throw Distance) is increased, the accuracy of the ink droplet landing position on the recording medium is improved, and the image quality is improved.

  In recent years, the TD has been narrowed to 1 to 2 mm for the purpose of further improving the accuracy of the ink droplet landing position on the recording medium, that is, further improving the image quality. On the other hand, in order to improve the uniformity of TD, it is required to increase the electrostatic adsorption force between the recording medium and the conveying member, and the TD can be changed depending on the environmental change such as temperature and humidity and the type of paper. In order to prevent the uniformity from decreasing, it is required to further increase the electrostatic adsorption force between the recording medium and the conveying member.

  For this reason, as shown in FIG. 12, the electrostatic attraction force generated between the recording head 32 and the conveyance belt 28 becomes strong, and a trouble may occur in which the conveyance belt 28 floats and contacts the recording head 32. there were. When the conveyance belt 28 comes into contact with the recording head 32, the conveyance belt 28 is stained with ink, ink is transferred from one recording head 32 to another recording head 32 via the conveyance belt 28, color mixing occurs, or the conveyance belt 28. There arises a problem that foreign matter adhered to the recording head 32 is mixed into the recording head 32 from the nozzles. In particular, a system that uses a transparent ink (reaction liquid) that mixes with yellow (Y), magenta (M), cyan (C), and black (K) inks to cause an agglomeration reaction, mainly for the purpose of improving image quality. In a so-called two-liquid system or a system in which different color inks such as K and Y are mixed and reacted (a so-called inter-ink reaction system), ink aggregation or discoloration occurs in the recording head 32, and recovery is not possible. It becomes possible.

  For this reason, the structure which suppresses the vibration of a conveyance belt by attracting | sucking a conveyance belt to the opposite side to the recording head side is devised (for example, refer patent document 1). In the configuration described in Patent Document 1, a voltage is applied to the comb-like electrodes built in the conveyor belt, and electrostatic attraction is generated on both the front and back surfaces of the conveyor belt, whereby a recording medium is placed on the surface of the conveyor belt. At the same time, the back surface of the conveyance belt is sucked by a member disposed on the opposite side of the recording belt side of the conveyance belt as a belt suction member.

Here, in order to continuously apply a high voltage to the electrodes built in the rotating conveyor belt, the electrodes are exposed along the belt rotating direction, and a conductive brush is slid onto the exposed portion of the electrodes. Although it is rubbed, high-voltage power feeding is performed at the rubbing portion between the conductive brush and the electrode, so that electric discharge is likely to occur, and electromagnetic waves generated with the electric discharge become a noise source and cause malfunction. It becomes. In addition, the occurrence of sparks at the rubbing portion between the conductive brush and the electrode damages the electrode and the conductive brush, and their life is significantly shortened.
JP 2002-145474 A

  The present invention has been made in consideration of the above facts, and suppresses the movement of the transport belt to the droplet discharge head side without increasing electromagnetic interference and damage to the transport belt.

  The droplet discharge device according to claim 1 is provided on a side opposite to the droplet discharge head side of the dielectric layer, a droplet discharge head for discharging droplets, a dielectric layer facing the droplet discharge head, and And a plurality of through-holes arranged in at least one of a circumferential direction and a width direction in the conductive layer. The belt holds a recording medium and conveys the recording medium so as to face the droplet discharge head. A conveying belt; a first charging unit that charges the conveying belt from the dielectric layer side; a potential maintaining unit that is electrically conductive to the entire conductive layer and maintains the conductive layer at a predetermined potential; and And a counter member facing the droplet discharge head.

  In the droplet discharge device according to claim 1, the recording medium is held on the conveyance belt and is conveyed while facing the droplet discharge head. During this time, the droplet discharge head discharges the droplets, so that the recording medium is discharged. Images etc. are recorded.

  Here, the transport belt includes a dielectric layer facing the droplet discharge head and a conductive layer provided on the opposite side of the dielectric layer from the droplet discharge head side. From the dielectric layer side by the first charging means. Charged. As a result, the recording medium is electrostatically attracted to the conveyance belt. Further, the potential maintaining means can be conducted to the entire area of the conductive layer, and the entire area of the conductive layer is maintained at a predetermined potential by the potential maintaining means. This stabilizes the state of charge in the entire area of the dielectric layer and stabilizes the electrostatic adsorption force of the recording medium, so that the lifting of the recording medium from the conveyance belt can be suppressed.

  In addition, a plurality of through holes arranged in at least one of the circumferential direction and the width direction are formed in the conductive layer of the transport belt, and the dielectric layer is exposed from the through holes. For this reason, while the conveyance belt is rotating, a portion of the dielectric layer exposed from the conductive layer and a member such as a roll that stretches the conveyance belt are rubbed to generate frictional charging in the dielectric layer. . Further, the facing member faces the droplet discharge head with the conveying belt interposed therebetween. For this reason, an electrostatic attraction force is generated between the conveyance belt and the opposing member, and the conveyance belt is urged to the opposite side of the conveyance belt to the droplet discharge head side.

  Here, the electrostatic attraction force between the conveyance belt and the droplet discharge head increases as the charge amount of the conveyance belt increases and the interval between the conveyance belt and the droplet discharge head (TD) becomes narrower. However, contact between the transport belt and the droplet discharge head is likely to occur.

  However, in the present invention, since the movement of the transport belt to the droplet discharge head side is suppressed by the electrostatic attraction force using the frictional charging described above, contact between the transport belt and the droplet discharge head is prevented. The charge amount of the transport belt can be increased and the TD can be further decreased. Thereby, the landing accuracy of the droplets on the recording medium can be further improved, and the image quality can be further improved.

  In addition, since the force for urging the conveying belt to the opposite side of the droplet discharge head side is an electrostatic attraction force using frictional charging, a high-voltage power feeding unit that rubs the electrodes becomes unnecessary, so the conveying belt It is possible to suppress the occurrence of electric discharge around and to suppress electromagnetic interference. In addition, since the occurrence of sparks around the conveyor belt can be prevented, damage to the conveyor belt can be suppressed, and the shortening of the conveyor belt can be suppressed.

  A droplet discharge device according to a second aspect is the droplet discharge device according to the first aspect, wherein the facing member can be brought into contact with the transport belt.

  In the liquid droplet ejection apparatus according to claim 2, the opposing member can come into contact with the conveying belt, and the portion exposed from the conductive layer of the dielectric layer and the opposing member rub against each other, whereby the dielectric layer is triboelectrically charged. And electrostatic attraction force is generated between the opposing member and the conveyor belt.

  Here, since the opposing member is so close that it comes into contact with the transport belt, the electrostatic attraction between the opposing member and the transport belt becomes strong, and the transport belt moves more toward the droplet discharge head. It can be further suppressed. In addition, since the conveying belt is biased by the opposing member by the electrostatic attraction force between the opposing member, the movement of the conveying belt to both the droplet ejection head side and the opposite side of the droplet ejection head side can be suppressed. Further, the uniformity of TD increases and the image quality improves.

  The droplet discharge device according to claim 3 is the droplet discharge device according to claim 1 or 2, further comprising second charging means for charging the transport belt from the conductive layer side. .

  In the droplet discharge device according to the third aspect, the transport belt is charged by the second charging unit from the conductive layer side. As a result, the surface on the conductive layer side of the transport belt is subjected to frictional charging by rubbing with a roll or the like and charging by the second charging means, so that the electrostatic attraction force between the opposing members is increased. This can further suppress the movement of the transport belt toward the droplet discharge head.

  The droplet discharge device according to claim 4 is the droplet discharge device according to any one of claims 1 to 3, wherein the potential maintaining means is a grounding means for grounding the conductive layer. It is characterized by.

  In the droplet discharge device according to the fourth aspect, since the entire area of the conductive layer is electrically connected to the grounding means and is grounded, the state of electric charge is stabilized in the entire area of the dielectric layer. Adsorption power is stabilized.

  Since the present invention is configured as described above, it is possible to suppress the movement of the transport belt to the droplet discharge head side without increasing electromagnetic interference and damage to the transport belt. In addition, the electrostatic attraction force between the recording medium and the conveyance belt can be stabilized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an ink jet recording apparatus 12 of the present embodiment. A paper feed tray 16 is provided in the lower part of the casing 14 of the ink jet recording apparatus 12, and the sheets P stacked in the paper feed tray 16 can be taken out one by one by a pickup roll 18. The taken paper P is transported by a plurality of transport roller pairs 20 constituting a predetermined transport path 22.

  An endless transport belt 28 is stretched around the drive roll 24 and the driven roll 26 above the paper feed tray 16. A recording head array 30 is disposed above the conveyor belt 28 and faces the flat portion 28F of the conveyor belt 28. This opposed area is an ejection area SE where ink droplets are ejected from the recording head array 30. The sheet P transported along the transport path 22 is held by the transport belt 28 and reaches the discharge area SE, and ink droplets corresponding to image information are attached from the recording head array 30 in a state of facing the recording head array 30. The

  In this embodiment, the recording head array 30 has a long shape in which the effective recording area is equal to or larger than the width of the paper P (the length in the direction orthogonal to the transport direction), and is yellow (Y) and magenta (M). , Four ink jet recording heads (hereinafter referred to as recording heads) 32 corresponding to the four colors of Sian (C) and Black (K) are arranged along the transport direction, and a full color image can be recorded. ing.

  Each recording head 32 is driven by a head drive circuit (not shown). The head drive circuit has a configuration in which, for example, the ejection timing of ink droplets and the ink ejection port (nozzle) to be used are determined according to image information and a drive signal is sent to the recording head 32.

  The recording head array 30 may be stationary in a direction orthogonal to the transport direction. However, if the recording head array 30 is configured to move as necessary, an image with higher resolution can be obtained by multi-pass image recording. Or the failure of the recording head 32 is not reflected in the recording result.

  Four maintenance units 34 corresponding to the respective recording heads 32 are arranged on both sides of the recording head array 30. As shown in FIG. 2, when performing maintenance on the recording head 32, the recording head array 30 is moved upward, and the maintenance unit 34 moves into the gap formed between the conveyance belt 28 and enters. . Then, a predetermined maintenance operation (suction, wiping, capping, etc.) is performed while facing the nozzle surface.

  As shown in FIG. 3, a charging roll 36 to which a power source 38 is connected is disposed on the upstream side of the recording head array 30. The charging roll 36 is driven while sandwiching the conveyance belt 28 and the paper P with the driven roll 26, and presses the paper P against the conveyance belt 28. At this time, since a predetermined potential difference is generated between the driven roll 26 grounded by the grounding portion 39, the sheet P can be charged and electrostatically attracted to the transport belt 28.

  A platen 48 is in contact with the back surface of the conveyance belt 28 in a region facing the recording head array 30. The platen 48 is disposed so as to be flush with the upper ends of the drive roll 24 and the driven roll, and the conveying belt 28 is pressed against the platen 48 and slidably moves. As a result, the sheet P electrostatically attracted to the transport belt 28 is transported in a stable posture.

  The platen 48 may be formed of a resin material such as POM or a metal material such as Al. When the platen 48 is formed of a metal material, the charge of the conveying belt 28 on the platen 48 is more stable by grounding. It can be kept in the state.

  A separation plate 40 is disposed on the downstream side of the recording head array 30 and separates the paper P from the conveyance belt 28. The peeled paper P is transported by a plurality of discharge roller pairs 42 that constitute a discharge path 44 on the downstream side of the peeling plate 40, and is discharged to a paper discharge tray 46 provided on the top of the housing 14.

  As shown in FIGS. 1 and 2, an ink tank 35 that stores ink of each color is disposed above the recording head array 30. Each recording head 32 is connected to each ink tank 35.

  Here, the configuration of the conveyor belt 28 will be described.

  As shown in FIG. 4, the conveyance belt 28 has a two-layer structure of a dielectric layer 28A and a conductive layer 28B. The dielectric layer 28A is a layer for holding electric charges supplied from the charging roll 36 for electrostatically adsorbing the paper P, and the conductive layer 28B is an electric charge supplied from the charging roll 36 to the dielectric layer 28A over a wide range. The dielectric layer 28A is provided on the outer peripheral side (recording head 32 side), and the conductive layer 28B is provided on the inner peripheral side (opposite side of the recording head 32 side).

The dielectric layer 28A is made of a resin material such as polyimide or polyamideimide, or a rubber material such as chloroprene rubber or urethane rubber, and has an electric resistance of 10 ¹² to 10 ¹⁷ Ω · cm and a thickness of 10 to 200 μm. Is desirable. The conductive layer 28B is preferably formed of a metal material such as Al or Ni, and has an electric resistance of 10 ⁻⁶ to 10 ⁶ Ω · cm and a thickness of 10 nm to 10 μm. The conductive layer 28B may be formed on one surface of the dielectric layer 28A by a known method such as vapor deposition, sputtering, or conductive paste printing.

  Here, as shown in FIG. 5A, when the transport belt 28 has a single-layer configuration of the dielectric layer 28A, the state of the electric charge held in the dielectric layer 28A is between the charging roll 36 and the driven roll 26. However, on the downstream side in the transport direction of the charging roll 36, the state of the electric charge held in the dielectric layer 28A changes due to discharge or the like. As a result, the electrostatic attraction force of the transport belt 28 becomes unstable, and there is a problem that the sheet P is lifted from the transport belt 28.

  On the other hand, since the dielectric layer 28A is exposed on the inner peripheral side, frictional charging is generated in the dielectric layer 28A due to the friction between the platen 48, the driving roll 24, the driven roll 26, and the dielectric layer 28A. An electrostatic attraction force F <b> 1 is generated between the conveyor belt 28. This has the advantage that the force for pulling the conveyor belt 28 toward the platen 48 increases, and the lifting of the conveyor belt 28 from the platen 48 is suppressed.

  On the other hand, as shown in FIG. 5B, the transport belt 28 has a two-layer structure of a dielectric layer 28A and a conductive layer 28B, provided that the conductive layer 28B is formed on the entire surface of the dielectric layer 28A and is conductive. When the layer 28 is grounded, the charge can be kept stable throughout the dielectric layer 28A. This has the advantage that the electrostatic attraction force of the transport belt 28 is stabilized and the lifting of the paper P from the transport belt 28 is suppressed.

  On the other hand, since the inner peripheral surface of the dielectric layer 28A is completely covered with the conductive layer 28B, frictional charging is unlikely to occur in the dielectric layer 28A, and the electrostatic force between the platen 48 and the conveying belt 28 is reduced. The suction force F1 is weakened. For this reason, when the charging potential of the conveying belt 28 is increased, the conveying belt 28 is lifted from the platen 48 by the electrostatic attraction force F2 between the conveying belt 28 and the recording head 32, and the TD is narrowed. In this case, there is a problem that contact between the conveyor belt 28 and the nozzle surface 32N of the recording head 32 occurs.

  Therefore, in the present embodiment, in order to stabilize the electrostatic adsorption force between the paper P and the conveyance belt 28, the conveyance belt 28 has a two-layer configuration including a dielectric layer 28A and a conductive layer 28B. The dielectric layer 28A can be triboelectrically charged.

  FIG. 4 shows a circumferential section of the conveyor belt 28. As shown in the drawing, through holes H are formed at a predetermined pitch in the width direction in the conductive layer 28B, and the dielectric layer 28A is exposed from the through holes H to the inner peripheral side.

  Here, the cross-sectional shape of the conveyance belt 28 in the circumferential direction is uniform. That is, as shown in FIG. 6, the conductive layer 28B has a configuration in which slits S and thin lines L extending in the circumferential direction are alternately arranged in the width direction, and the dielectric layer extends from the slit S to the inner circumferential side. 28A is exposed.

  The conductive layer 28B has a thickness of 10 nm to 10 μm, and the step between the conductive layer 28B and the portion exposed from the slit S of the dielectric layer 28A is extremely small. Therefore, as shown in FIGS. 4 and 6, the portion exposed from the slit S of the dielectric layer 28A and the platen 48, the driving roll 24, and the driven roll 26 rub against each other, and frictional charging occurs in the dielectric layer 28A. When the conveying belt 28 passes between the recording head 32 and the platen 48, an electrostatic attractive force F1 is generated between the dielectric layer 28A and the platen 48.

On the other hand, an electrostatic attraction force F2 is generated between the conveying belt 28 and the nozzle surface 32N of the recording head 32 due to the generation of electrostatic induction. In this embodiment, the charging potential V of the conveying belt 28 is 1000 [V], the distance (TD) d between the conveying belt 28 and the nozzle surface 32N of the recording head 32 is 1.5 [mm], and the recording head of the conveying belt 28 is used. The area S facing the 32 nozzle surfaces 32N is 0.09 [m ² ], and the electrostatic attractive force F2 is 0.18 [N] as shown by the following equation (1).

F2 = 1 / 2εS (V / d) ² = 0.18 [N], ε is the dielectric constant of air (1)
That is, an upward (at the recording head 32 side) electrostatic attraction force F2 and a downward (toward the platen 52 side) electrostatic attraction force F1 act on the transport belt 28. As a result, the force for pulling the conveying belt 28 toward the platen 48 increases, so that the movement of the conveying belt 28 toward the recording head 32 can be suppressed.

In this embodiment, the dielectric layer 28A is a PET layer having an electrical resistance of 10 ¹⁷ Ω · cm and a thickness of 75 μm, and the conductive layer 28B is an electrical resistance of 10 ⁻⁶ Ω · cm and a thickness of 0.1 μm. The layer of Al, the width of the conveying belt 28 is 365 mm, the circumferential length of the conveying belt 28 is 762 mm, the width of the slit S is 50 μm, the ratio of the slit S in the conductive layer 28B is 5%, the material of the platen 48 is ABS resin, width × When the length × thickness was set to 350 mm × 300 mm × 6 mm, no lifting of the conveying belt 28 from the platen 48 was observed, and no contact between the conveying belt 28 and the nozzle surface 32N of the recording head 32 occurred. .

  Accordingly, it is possible to increase the charge amount of the transport belt 28 and narrow the TD while preventing the contact between the transport belt 28 and the nozzle surface 32N of the recording head 32. Therefore, the landing accuracy of ink droplets on the paper P can be reduced. Thus, the image quality can be further improved.

  In addition, since the force for urging the conveying belt 28 toward the platen 48 is an electrostatic attraction force using frictional charging, a high-voltage power feeding unit that rubs the electrodes is not necessary, and therefore, around the conveying belt 28. Can be suppressed, and electromagnetic interference can be suppressed. Further, since the occurrence of sparks around the conveyor belt 28 can be prevented, damage to the conveyor belt 28 can be suppressed, and shortening of the conveyor belt 28 can be suppressed.

  Here, in the conductive layer 28B, the slits S and the thin lines L extending in the circumferential direction are alternately arranged and are not connected in the width direction, and thus do not conduct directly in the width direction. However, the driven roll 26 grounded by the grounding portion 39 is in contact with the entire width of the conductive layer 28B, and the entire circumference of the conductive layer 28B is grounded. As a result, the charge can be kept stable over the entire width of the entire circumference of the dielectric layer 28A, and the adsorbed state of the paper P on the transport belt 28 can be stabilized.

  Next, the conveyance belt 50 according to another embodiment of the conveyance belt 28 will be described.

  FIG. 7 shows a cross section in a direction (in the direction of arrow A in FIG. 8) that intersects the circumferential direction of the conveyor belt 50 at a predetermined angle (for example, 45 degrees). As shown in the figure, the transport belt 50 has a two-layer configuration of a dielectric layer 50A and a conductive layer 50B, and through holes H are formed in the conductive layer 50B at a predetermined pitch in the width direction and the circumferential direction. The dielectric layer 50A is exposed from H to the inner peripheral side.

  Here, the cross-sectional shape of the conveyance belt 50 in the direction of arrow A is uniform. That is, as shown in FIG. 8, the conductive layer 50B has a configuration in which slits S and thin lines L extending along the direction of arrow A are alternately arranged in a direction perpendicular to the direction of arrow A. The dielectric layer 50A is exposed to the inner peripheral side.

  Similarly to the above-described conveyor belt 28, the conductive layer 50B has a thickness of 10 nm to 10 μm, and the step between the conductive layer 50B and the portion exposed from the slit S of the dielectric layer 50A is extremely small. For this reason, as shown in FIGS. 7 and 8, the portion exposed from the slit S of the dielectric layer 50A and the platen 48, the driving roll 24, and the driven roll 26 rub against each other, and frictional charging occurs in the dielectric layer 50A. When the conveying belt 50 passes between the recording head 32 and the platen 48, an electrostatic attraction force F1 is generated between the dielectric layer 50A and the platen 48.

  Here, the slit S does not extend to both ends in the width direction of the conductive layer 50B, and there are strip-like portions extending in the circumferential direction at both ends in the width direction of the conductive layer 50B. All the thin lines L of the conductive layer 50B are connected to the band-shaped portions at both ends in the width direction, and the conductive layer 50B is directly conducted in the width direction and the circumferential direction. Further, the conductive layer 50 </ b> B is in contact with the driven roll 26 that is grounded by the ground portion 39. Accordingly, since the conductive layer 50B is grounded over the entire circumference, the charge can be kept stable over the entire circumference of the dielectric layer 50A, and the adsorption state of the paper P onto the transport belt 50 can be maintained. It can be stabilized.

  Next, the conveyance belt 60 according to another embodiment of the conveyance belt 28 will be described.

  9A and 9B show a cross section in the circumferential direction of the conveyor belt 60. FIG. As shown in the figure, the conveyor belt 60 has a two-layer configuration of a dielectric layer 60A and a conductive layer 60B, and a cross-sectional area in which through holes H are opened at a predetermined pitch in the width direction of the conductive layer 60B. There are places where H does not exist.

  As shown in FIG. 10, the through hole H is a circular hole C arranged along the width direction and the circumferential direction of the conductive layer 60 </ b> B, and a cross-section at a position where the circular holes C are aligned in the width direction is shown in FIG. 8. As shown in FIG. 8A, a cross section at a position between the circular holes C adjacent in the circumferential direction is as shown in FIG.

  Further, like the above-described conveyor belts 28 and 50, the conductive layer 60B has a thickness of 10 nm to 10 μm, and the step between the conductive layer 60B and the portion exposed from the circular hole C of the dielectric layer 60A becomes extremely small. Yes. For this reason, the portion exposed from the circular hole C of the dielectric layer 60A and the platen 48, the driving roll 24, and the driven roll 26 rub against each other, and frictional electrification occurs in the dielectric layer 60A. An electrostatic attraction force is generated between the dielectric layer 60 </ b> A and the platen 48 while passing between the platen 48.

  Here, the conductive layer 60B is connected in the width direction and the circumferential direction, and is directly conducted in the width direction and the circumferential direction. The conductive layer 60 </ b> B is in contact with the driven roll 26 that is grounded by the ground portion 39. Accordingly, since the conductive layer 60B is grounded over the entire circumference, the charge can be kept stable over the entire circumference of the dielectric layer 60A, and the adsorption state of the paper P onto the transport belt 60 can be maintained. It can be stabilized.

  Next, a second embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted.

  As shown in FIG. 11, a charging roll 70 is disposed on the inner peripheral side of the conveyor belt 28. The charging roll 70 is in contact with the inner peripheral surface of the lower flat surface 28F ′ of the conveying belt 28.

  Here, as shown in FIGS. 4 and 6, the conductive layer 28B exists on the inner peripheral surface of the conveyor belt 28, but the conductive layer 28B has a slit S that exposes the dielectric layer 28A to the inner peripheral side. The part exposed from the slit S of the dielectric layer 28 </ b> A can be brought into contact with the charging roll 70. For this reason, the dielectric layer 28 </ b> A can be charged from the charging roll 70.

  As a result, frictional charging due to friction between the platen 48, the driving roll 24, and the driven roll 26 and charging by the charging roll 70 are performed on the inner peripheral surface of the conveying belt 28, so that the platen 48 and the conveying belt are charged. The electrostatic attraction force F1 between the conveyor belt 28 and the recording belt 32 can be further suppressed.

  In the first and second embodiments, the charging means for charging the conveying belt 28 from the outer peripheral side or the inner peripheral side is a charging roll, but other corotrons can also be applied.

  In the first and second embodiments, since the platen 48 that contacts the back surface of the conveyor belt 28 is installed, the conveyor belt 28 is urged to the platen 48 by the electrostatic adsorption force, and the vertical fluctuation of the conveyor belt 28 is suppressed. However, the effect of the present invention can be obtained if a member facing the recording head 32 is installed with the conveying belt 28 interposed therebetween, and it is essential to install the platen 48 that contacts the back surface of the conveying belt 28. Not.

  In the first and second embodiments, the conductive layer of the transport belt is grounded by the grounding unit 39. However, it is sufficient that the conductive layer of the transport belt is maintained at a predetermined potential, and grounding is not essential.

  Further, the pattern of the conductive layer of the transport belt is not limited to the above-described example, and other patterns such as a lattice shape can be applied.

  In the first and second embodiments, the present invention has been described by taking the ink jet recording apparatus as an example. However, the present invention is not limited to the ink jet recording apparatus, and the display is performed by discharging colored ink onto a polymer film. The present invention can be applied to a general liquid droplet ejection apparatus for various industrial uses such as production of a color filter for liquid crystal and formation of an EL display panel by discharging an organic EL solution onto a substrate.

  In addition, the “recording medium” that is a target of image recording in the droplet discharge device of the present invention includes a wide range of objects as long as the droplet discharge head discharges droplets. Accordingly, the recording medium includes recording paper, an OHP sheet, and the like, but also includes, for example, a polymer film.

  Furthermore, in the first and second embodiments, the present invention has been described by taking as an example a configuration in which a plurality of inkjet recording heads shorter than the width of the paper P are arranged in the width direction of the paper P as a unit. For example, the present invention can be applied to a configuration in which an inkjet recording head having a length shorter than the width of the paper P is moved in the width direction of the paper P.

1 is a side view illustrating an outline of an ink jet recording apparatus according to a first embodiment of the present invention. 1 is a side view illustrating an outline of an ink jet recording apparatus according to a first embodiment of the present invention. It is a side view which shows the outline of the printing part of the inkjet recording device of 1st Embodiment of this invention. FIG. 3 is a diagram illustrating a cross section in the circumferential direction of the conveyance belt of the ink jet recording apparatus according to the first embodiment of the present invention. (A) is sectional drawing which shows the conveyance belt of 1 layer structure of a dielectric layer, (B) is sectional drawing which shows the conveyance belt of 2 layers structure of a dielectric layer and a conductive layer. FIG. 3 is a cross-sectional view illustrating an inner peripheral surface of the conveyance belt of the ink jet recording apparatus according to the first embodiment of the present invention. It is a figure which shows the cross section of the circumferential direction of the modification of the conveyance belt of the inkjet recording device of 1st Embodiment of this invention. It is sectional drawing which shows the surface of the inner peripheral side of the modification of the conveyance belt of the inkjet recording device of 1st Embodiment of this invention. (A), (B) is a figure which shows the cross section of the circumferential direction of the modification of the conveyance belt of the inkjet recording device of 1st Embodiment of this invention. It is sectional drawing which shows the surface of the inner peripheral side of the modification of the conveyance belt of the inkjet recording device of 1st Embodiment of this invention. It is a side view which shows the outline of the printing part of the inkjet recording device of 2nd Embodiment of this invention. It is a side view which shows typically the recording head and the conveyance belt in the conventional inkjet recording device.

Explanation of symbols

12 Inkjet recording device (droplet ejection device)
28 Conveying belt 28A Dielectric layer 28B Conductive layer 32 Inkjet recording head (droplet ejection head)
36 Charging roll (first charging means)
39 Grounding part (potential maintaining means, grounding means)
48 Platen (opposing member)
50 Conveying belt 50A Dielectric layer 50B Conductive layer 60 Conveying belt 60A Dielectric layer 60B Conductive layer 70 Charging roll (second charging means)
H Through hole P Paper (recording medium)

Claims (4)

A droplet discharge head for discharging droplets;
A dielectric layer facing the droplet discharge head; and a conductive layer provided on the opposite side of the dielectric layer from the droplet discharge head side, and a plurality of the layers arranged in at least one of a circumferential direction and a width direction on the conductive layer A conveying belt that holds a recording medium and conveys the recording medium to face the droplet discharge head;
First charging means for charging the conveyor belt from the dielectric layer side;
A potential maintaining means for allowing conduction to the entire area of the conductive layer and maintaining the conductive layer at a predetermined potential;
A facing member that faces the droplet discharge head with the conveyor belt interposed therebetween;
A droplet discharge apparatus comprising:   The droplet discharge device according to claim 1, wherein the facing member is capable of contacting the conveying belt.   The droplet discharge device according to claim 1, further comprising a second charging unit that charges the transport belt from the conductive layer side.   4. The liquid droplet ejection apparatus according to claim 1, wherein the potential maintaining means is a grounding means for grounding the conductive layer.

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