JP4696930B2 - Droplet discharge device - Google Patents

Description

  The present invention relates to a droplet discharge apparatus including a droplet discharge head that discharges droplets, a transport member that holds a recording medium and transports the recording medium so as to face the droplet discharge head, and a cleaning unit that cleans the transport member.

  In the ink jet printer as a droplet discharge device, when a paper jam occurs during printing, ink droplets are discharged from the ink jet recording head (droplet discharge head) in a state where there is no paper on the conveyance belt (conveyance member) and conveyed. Ink may adhere to the belt. In addition, the conveyance belt is gradually soiled by ink mist generated when ink droplets are ejected from the ink jet recording head during printing. Further, when ink droplets that are irrelevant to printing are ejected toward the transport belt for the purpose of preventing clogging of dummy nozzles, that is, unused nozzles, ink adheres to the transport belt. For this reason, it is necessary to install a cleaning means for cleaning ink adhering to the conveyor belt.

  Examples of the cleaning means include a blade that scrapes off ink adhered to the conveyance belt, an absorption roll that absorbs ink adhered to the conveyance belt, and the like. Ink cannot be sufficiently removed from the conveyor belt only by cleaning the conveyor belt. As a result, a problem of smearing of the recording medium due to ink residue occurs. For this reason, for the purpose of improving the cleaning performance of the conveyor belt by the cleaning means, a coating layer is formed on the surface of the conveyor belt, or cleaning liquid such as water is supplied to the surface of the conveyor belt to remove the ink adhered to the conveyor belt. The adhesion between the ink and the conveyor belt is reduced by dissolving the ink (for example, see Patent Documents 1 to 3).

  Here, when the coating layer is formed on the surface of the transport belt, the transport belt coating layer gradually deteriorates due to the rubbing against the cleaning device or paper, and the cleaning performance of the transport belt by the cleaning device gradually increases. descend.

In addition, a large amount of cleaning liquid is required to supply the cleaning liquid to the surface of the conveyor belt and dissolve the ink adhering to the conveyor belt. This increases the consumption of the cleaning liquid, and the cleaning liquid recovery mechanism. Becomes larger and more complicated. Therefore, the cost increases and the apparatus becomes larger.
JP 2005-53663 A JP 2004-137032 A JP 2004-196505 A

  The present invention has been made in consideration of the above facts, and it is an object of the present invention to improve the cleaning performance of the conveying member by the cleaning means, and to suppress the increase in cost and the enlargement of the apparatus.

The liquid droplet ejection apparatus according to claim 1, a liquid droplet ejection head that ejects liquid droplets, a conveyance member that holds a recording medium and conveys the recording medium to face the liquid droplet ejection head, and cleaning that cleans the conveyance member means and said droplet a coating solution repellency of the liquid ejected from the ejection head to have a, a coating means for applying to said conveying member, the surface tension gamma ₀ of the coating _liquid, the critical surface tension of the conveying member γ _b and the surface tension γ _{i of the} liquid discharged from the droplet discharge head satisfy the following expressions (1) and (2) .
γ ₀ <γ _b (1)
γ ₀ <γ _i (2)

The liquid droplet ejection apparatus according to claim 2 , a liquid droplet ejection head that ejects liquid droplets, a conveyance member that holds a recording medium and conveys the recording medium to face the liquid droplet ejection head, and cleaning that cleans the conveyance member And means for applying a coating liquid having a property of repelling the liquid discharged from the droplet discharge head to the transport member, the liquid discharged from the droplet discharge head being water-based ink, the application liquid is you being a liquid having water repellency.

In the liquid droplet ejection apparatus according to claim 1 or 2, the recording medium is held by the transport member and transported while facing the liquid droplet ejection head, and the liquid droplet ejection head ejects the liquid droplets. Thereby, an image or the like is recorded on the recording medium. In addition, the coating liquid is applied to the conveying member by a coating means, and a film of the coating liquid is formed. Since this coating liquid has the property of repelling the liquid discharged from the droplet discharge head, the liquid discharged from the droplet discharge head and adhering to the coating liquid film aggregates on the coating liquid film. To do. As a result, the adhesion force between the liquid discharged from the droplet discharge head and the transport member can be suppressed, so that when the transport member is cleaned by the cleaning means, the liquid discharged from the droplet discharge head and attached to the transport member is removed. It peels easily from the conveying member.

  Here, as long as the coating liquid film is formed on the entire surface of the conveying member, the purpose of suppressing the adhesion between the liquid discharged from the droplet discharge head and the conveying member is achieved, and the coating liquid film thickness is reduced. Increasing the thickness does not contribute to achieving the objective. For this reason, since the supply amount of the coating liquid to the conveying member can be reduced, the consumption of the coating liquid can be reduced, and the coating liquid recovery mechanism can be reduced in size and simplified. Therefore, cost can be reduced and the enlargement of the apparatus can be suppressed.

  Since the present invention is configured as described above, it is possible to improve the cleaning performance of the conveying member by the cleaning means, and it is possible to suppress the increase in cost and the size of the apparatus.

  Hereinafter, a first embodiment 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.

  Above the paper feed tray 16, an endless transport belt 28 is stretched around a drive roll 24 and driven rolls 26, 27, and 29. The driving roll 24 and the driven roll 26 are disposed substantially horizontally, and the driven rolls 27 and 29 are disposed substantially horizontally below the driving roll 24 and the driven roll 26.

  A recording head array 30 is disposed above the conveyor belt 28 and faces a flat portion 28 </ b> F of the conveyor belt 28 between the drive roll 24 and the driven roll 26. 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.

  Further, an ink tank 35 for storing ink of each color is disposed above the recording head array 30. Each recording head 32 is connected to each ink tank 35.

  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 grounded follower roll 26, the sheet P can be electrostatically adsorbed to the transport belt 28 by applying an electric charge to the sheet P.

  A separation claw 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 conveyed by a plurality of discharge roller pairs 42 that constitute a discharge path 44 on the downstream side of the peeling claw 40 and discharged to a paper discharge tray 46 provided at the upper part of the housing 14.

  A belt cleaning unit 48 is disposed below the peeling claw 40. The belt cleaning unit 48 is in contact with a portion of the transport belt 28 wound around the drive roll 24 and scrapes off the ink and the like adhering to the transport belt 28, and is scraped off from the transport belt 28 by the blade 49. And a collection box 51 for collecting ink and the like. Note that an absorber 53 is spread on the bottom of the collection box 51 and absorbs the liquid dropped from the blade 49.

  An oil application unit 62 is disposed below the driven roll 27. The oil application unit 62 is rotatably supported by a case 64, a belt-like web 66, a case 64, and a feed shaft 68 wound around one end side in the longitudinal direction of the web 66, and a case 64. The web 66 is wound around the other end side in the longitudinal direction of the web 66, and is press-contacted so as to be rotatably supported by the case 66 and press the web 66 against a portion of the conveyor belt 28 wound around the driven roll 27. A roll 90 and pinch rolls 92 and 94 that are rotatably supported by the case 64 and apply tension to the web 66 are provided.

  The feed shaft 68, the pinch roll 92, the pressure contact roll 90, the pinch roll 94, and the take-up shaft 88 are arranged in the order described from the upstream side to the downstream side in the rotation direction of the transport belt 28, and the web 66 is stretched. Yes. The web 66 is impregnated with silicone oil.

  Here, the take-up shaft 88 is driven by a motor (not shown). When the take-up shaft 88 is rotated by the drive of the motor, the web 66 is fed from the feed shaft 68, and a minute amount is obtained. Each is conveyed to the winding shaft 88 side. As a result, silicone oil is applied to the conveyor belt 28 at the nip portion between the pressure contact roll 90 and the driven roll 27, and a silicone oil film is formed on the conveyor belt 28. On the other hand, the ink ejected from the recording head 32 is a water-based ink. For this reason, when ink adheres to the transport belt 28 by unnecessary ink discharge at the time of ink mist or paper jam, or a dummy jet discharged onto the transport belt 28, the repellency of the silicone oil film on the transport belt 28 is reduced. The ink aggregates due to the water effect. Therefore, the force of ink adhering to the conveyance belt 28 can be suppressed, and the ink is easily peeled from the conveyance belt 28 when the conveyance belt 28 is cleaned by the blade 49.

  Here, since the dummy jet is performed at a short cycle such as once every several tens of seconds in order to prevent thickening of the ink in the recording head 32, the dummy jet is always on the transport belt 28 as in the present embodiment. It is effective to form a silicone oil film.

  Note that the web 66 may be continuously conveyed by a minute amount or intermittently every predetermined number of sheets.

  The transport belt 28 is made of a resin such as PET, PI, PA, or PC, or a rubber material such as CR, NBR, HNBR, or urethane rubber, and the surface thereof is coated. The blade 49 is made of a rubber material such as fluorine rubber, NBR, or HNBR, a thin metal plate such as SUS, or a film formed of a resin such as polyurethane or PET. The web 66 is preferably a non-woven fabric formed of polyester, polyamide, or the like, but may be changed to another as long as it can be impregnated with a predetermined amount of ink and wound.

  Further, as described above, silicone oil is used as the liquid (hereinafter referred to as coating liquid) applied to the conveyor belt 28 by the web 66, and water-based ink is used as the ink. Here, the coating liquid is suitable for repelling ink. For water-based ink, in addition to silicone oil, higher fatty acids such as oleic acid and linoleic acid, dibutyl phthalate, diisodecyl phthalate, dibutyl maleate Water-repellent liquids such as water-insoluble alcohols such as n-decanol and dimethylbutanol, fluorine oil, mineral oil, and vegetable oil can be used. For oil-based ink, a liquid having high oil repellency such as water can be used.

In addition, in order to stabilize the application of the coating liquid onto the conveyor belt 28, the kinematic viscosity of the coating liquid is desirably in the range of 10 to 10 ⁴ mm ² / s, and in the range of 50 to 10 ² mm ² / s. Is more desirable.

  On the other hand, if the coating thickness of the coating liquid is too thick, the oil may permeate the paper P and the paper P may repel the ink, and the image quality may be adversely affected. Since the cleaning of the ink by the blade 49 is not performed satisfactorily, it is necessary to set the coating thickness of the coating liquid in an appropriate range. A suitable range of the coating thickness of the coating solution is 1 nm to 20 μm.

  Further, the coating solution needs to be non-volatile at room temperature. Specifically, the vapor pressure is 13.33 Pa or less at 25 ° C. Further, the coating liquid needs to be incompatible with ink. Specifically, the solubility in ink is 0.1 wt% or less at normal temperature (25 ° C.).

Further, since the coating liquid needs to spread out on the conveyor belt 28, the relationship of the following formula (1) is necessary. However, as shown in FIG. 4, the surface tension of the coating liquid T is γ ₀ and the critical surface tension γ _b of the conveyor belt 28 is set. The critical surface tension is the relationship between the surface tension of various liquids and the contact angle θ of the solid surface, when cos θ is corrected to 1 (that is, when the contact angle of the liquid with respect to the solid surface becomes 0 °). Refers to the surface tension. In general, a solid surface wets well with a liquid having a surface tension smaller than the critical surface tension of the surface.

γ ₀ <γ _b (1)
Further, in order to give the coating solution water repellency, the relationship of the following formula (2) is required. However, the surface tension of the ink I is γ _i .

γ ₀ <γ _i (2)
As a result, the ink I aggregates without spreading on the film of the coating liquid T. The transport belt 28 is a PET belt with a critical surface tension γ _b of about 43 [mN / m], the coating liquid is silicone oil with a surface tension γ ₀ of about 20 [mN / m], and the ink has a surface tension γ _i. As a result of conducting an experiment for evaluating the cleaning performance as a water-based ink of about 30 [mN / m], there was no ink residue on the conveying belt 28, and the cleaning property was good.

  Here, as long as the film of the coating liquid T is formed on the entire surface of the transport belt 28, the adhesion force between the transport belt 28 and the ink is reduced, and the purpose of increasing the film thickness of the coating liquid T is achieved. Does not contribute. For this reason, since the supply amount of the coating liquid to the conveyance belt 28 can be reduced, the consumption amount of the coating liquid can be reduced, and the recovery mechanism for the coating liquid T can be reduced in size and simplified. Therefore, cost can be reduced and the enlargement of the apparatus can be suppressed.

  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. 5, in this embodiment, the oil application unit 96 and the backup plate 99 are opposed to each other between the driven roll 26 and the driven roll 27 with the conveying belt 28 interposed therebetween. The oil application unit 96 faces the outer peripheral surface of the conveyor belt 28, and the backup plate 99 is in contact with the inner peripheral surface of the conveyor belt 28.

  The oil application unit 96 includes a case 98, an oil application roll 102 that is rotatably supported by the case 98, and an oil blade 104 that is supported by the case 98. The oil application roll 102 is pressed against the backup blade 99 with the conveyance belt 28 interposed therebetween, and rotates following the conveyance belt 28. The oil application roll 102 is formed of a porous material such as polyethylene or urethane, impregnated with silicone oil, and applies the silicone oil to the conveyor belt 28.

  The oil application roll 102 may be a drive roll. In this case, the oil application roll 102 can be prevented from slipping with respect to the transport belt 28.

  The oil blade 104 is in contact with the conveyor belt 28 on the downstream side in the rotational direction of the conveyor belt 28 with respect to the oil application roll 102, and scrapes off the excess silicone oil applied to the conveyor belt 28. The film thickness is set to a predetermined thickness. The oil blade 104 is made of a rubber such as fluorine rubber or NBR, a thin metal plate such as SUS, a resin film such as polyurethane or PET, or the like.

  In addition, an absorbing member 106 such as a sponge is spread on the bottom of the case 98, and the absorbing member 106 absorbs the silicone oil scraped off from the conveying belt 28 by the oil blade 104.

  Next, a third embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st, 2nd embodiment, and description is abbreviate | omitted.

  As shown in FIG. 6, in this embodiment, the oil application unit 108 is disposed below the driven roll 27. The oil application unit 108 includes a case 110 that contains silicone oil, an oil application roll 112 that is rotatably supported by the case 110, an oil supply roll 114, and an oil blade 116 that is supported by the case 110. Yes.

  The oil application roll 112 is in contact with the portion of the transport belt 28 wound around the driven roll 27, and the oil supply roll 114 is in contact with the oil application roll 116. The oil application roll 112 and the oil supply roll 114 are connected to a common drive source (not shown) by a gear train (not shown), and are driven by the common drive source. The lower part of the oil supply roll 114 is immersed in the silicone oil in the case 110. The oil supply roll 114 is formed of a porous material such as polyethylene or urethane, absorbs the silicone oil in the case 110, and supplies it to the oil application roll 112.

  The oil blade 116 is in contact with the oil application roll 112 on the downstream side of the oil supply roll 114 in the rotation direction of the oil application roll 112 and on the upstream side of the driven roll 27 in the rotation direction of the oil application roll 112. The excess silicone oil on the roll 112 is scraped off, and the film thickness of the silicone oil is set to a predetermined thickness on the oil application roll 112. Then, silicone oil having a predetermined film thickness is transferred from the oil application roll 112 to the conveyor belt 28.

  As the oil application roll 112, a silicone rubber roll or a metal roll having a surface coated with Teflon (registered trademark) is used. The oil blade 116 is made of a rubber such as fluorine rubber or NBR, a thin metal plate such as SUS, a resin film such as polyurethane or PET, or the like.

  Next, a fourth embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st thru | or 3rd embodiment, and description is abbreviate | omitted.

  As shown in FIG. 7, in this embodiment, the belt cleaning / oil application unit 118 is disposed below the peeling claw 40, and the belt cleaning unit 120 is disposed below the driven roll 27.

  The belt cleaning and oil application unit 118 is rotatably supported by the case 122, the belt-like web 124, the case 122, and the feed shaft 126 wound around one end in the longitudinal direction of the web 124, and the case 122. The winding shaft 128 is wound around the other end in the longitudinal direction of the web 124, and is rotatably supported by the case 122. The web 124 is pressed against the portion of the conveyor belt 28 wound around the drive roll 24. Pressure contact rolls 130 and 132, and a pinch roll 134 that is rotatably supported by the case 122 and applies tension to the web 124.

  The feed shaft 126, the pressure contact roll 130, the pinch roll 134, the pressure contact roll 132, and the take-up shaft 128 are arranged in the order described from the downstream side to the upstream side in the rotation direction of the conveyor belt 28, and stretch the web 124. Yes. The web 124 is impregnated with silicone oil.

  Here, the take-up shaft 128 is driven by a motor (not shown). When the take-up shaft 128 is rotated by the drive of the motor, the web 124 is sent out from the feed shaft 126, and a minute amount is obtained. Each is conveyed to the winding shaft 128 side. As a result, silicone oil is applied to the conveyor belt 28 at the nip portion N1 between the pressure contact roll 130 and the drive roll 24, and a film of silicone oil is formed on the conveyor belt 28.

  At this time, since the amount of silicone oil impregnated in the web 124 is reduced, the water absorption of the web 124 is increased at the nip portion between the pressure contact roll 132 and the drive roll 24, and the ink adhering to the conveyance belt 28 is absorbed by the web 124. Is done. Thereby, the contamination of the web 124 at the nip portion N2 between the drive roll 24 and the pressure contact roll 30 can be suppressed.

  Further, the belt cleaning unit 120 abuts on a portion of the transport belt 28 wound around the driven roll 27 and scrapes the ink attached to the transport belt 28 from the transport belt 28 by the blade 49. A recovery box 51 that recovers the ink and the like, and an absorber 53 that absorbs the liquid in the recovery box 51. As a result, the ink that has not been cleaned from the transport belt 28 by the belt cleaning and oil application unit 118 is cleaned.

  Next, a fifth embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st thru | or 4th embodiment, and description is abbreviate | omitted.

  As shown in FIG. 8, in this embodiment, a belt cleaning / oil application unit 136 is disposed below the peeling claw 40. The belt cleaning / oil application unit 136 includes a first blade 138 and a second blade 140 that are in contact with a portion of the transport belt 28 wound around the drive roll 24, and proximal sides of the first blade 138 and the second blade 140. And a case 144 supporting the above.

  The case 144 is partitioned into two chambers, a waste ink storage chamber 144A and an oil storage chamber 144B, by the base end side of the first blade 138. The waste ink storage chamber 144 </ b> A stores waste ink or the like that is scraped from the transport belt 28 by the first blade 138 and falls along the first blade 138. The oil storage chamber 144B is connected to a tank (not shown) that stores silicone oil, and stores the silicone oil supplied from the tank. In addition, the first blade 138 is juxtaposed upstream of the second blade 140 in the rotation direction of the transport belt 28.

  Here, as shown in FIGS. 9A and 9B, a plurality of ribs 140A extending from the proximal end side to the distal end side are formed on the surface of the second blade 140 on the first blade 138 side, A slit S is formed between the first blade 138 and the second blade 140 by the rib 140A. The slit S faces the oil storage chamber 144B, and the silicone oil in the oil storage chamber 144B can be supplied to the transport belt 28 through the slit S.

  Further, the rib 140A is cut in the middle of the tip side of the second blade 140, and the silicone oil spreads over the entire tip of the second blade 140. As a result, the silicone oil is also applied to the range of the conveyor belt 28 facing the rib 140A. Further, the silicone oil applied to the conveyor belt 28 is stretched by the second blade 140 to have a predetermined thickness.

  As described above, in the present embodiment, the cleaning means for cleaning the transport belt 28 and the application means for applying the coating liquid to the transport belt 28 are integrated into one place, so that space efficiency can be improved.

  The first blade 138 is formed of a resin (polyurethane, PET, etc.) that is not affected by the ink and the coating liquid, rubber (fluorine rubber, NBR, HNBR, etc.), or metal (SUS, etc.). The second blade 140 is formed of a resin (polyurethane, PET, etc.), rubber (fluororubber, NBR, HNBR, etc.) or metal (SUS, etc.) that is not affected by the coating liquid.

In this embodiment, silicone oil is used as the coating liquid, but various liquids similar to those in the first to fourth embodiments can be used. However, considering the stability of the electrostatic attraction between the conveying belt 28 and the sheet P, the volume resistivity value of the coating solution is desirably ¹⁰ 12 ^{~10 16 Ω} · ^cm, and more preferably ¹⁰ 14 ~10 ¹⁶ Ω · cm.

  In the present embodiment, the silicone oil is mechanically supplied from the oil reservoir chamber 144B to the conveyor belt 28 by the pump 146 provided in the flow path connecting the oil reservoir chamber 144B and the tank. However, as shown in FIG. 10, a reserve tank 148 communicated with the atmosphere is provided between the oil reservoir chamber 144 </ b> B and the tank, and the liquid level of the silicone oil in the reserve tank 148 is from the tip of the second blade 140. A reserve tank 148 may be installed so as to be higher, and silicone oil may be supplied from the oil storage chamber 144B to the conveyor belt 28 due to a water head difference.

  Further, as shown in FIGS. 9A and 9B, in this embodiment, the flow path of the silicone oil between the first blade 138 and the second blade 140 is the slit S. However, as shown in FIGS. 11A and 11B, a core material 150 made of a porous material is provided between the first blade 138 and the second blade 140, and silicone oil is applied by the capillary force of the core material 150. May be sucked up to the tip of the first blade 138 and the second blade 140. Here, as the core material 150, a resin or rubber sponge molded product or a non-woven fabric that is not affected by a coating liquid such as silicone oil can be used. Further, as a material of the core material 150, for example, polyvinyl alcohol or polyurethane can be applied. Moreover, the hole diameter of the core material 150 is preferably about 1 to 100 μm.

  In addition, as shown in FIG. 12, a configuration in which a rib 140A is provided on the second blade 140 and the core material 150 is filled between the first blade 138, the second blade 140, and the rib 140A is also applicable.

  Further, as shown in FIG. 13A, the first blade 138 and the second blade 140 may be integrally formed. As the formation method, as shown in FIG. 13 (B), one side of the porous body is subjected to treatment such as hot pressing, solvent application, light irradiation, gas spraying, etc. The first blade 138 having water repellency, low water absorption and high rigidity can be used as the first blade 138, and the untreated portion of the porous body can be used as the second blade 140 having high water absorption and low rigidity. is there.

  In the present embodiment, as shown in FIG. 14A, the contact angle θ between the first blade 138 and the conveyor belt 28 is an obtuse angle, but as shown in FIG. 14B, the first blade The contact angle θ between 138 and the conveyor belt 28 may be an acute angle. When the contact angle θ is an obtuse angle, the cleaning performance is improved, and when the contact angle θ is an acute angle, the wear resistance of the first blade 138 and the conveyor belt 28 is increased.

  Here, depending on the environmental temperature, the viscosity of the coating solution may change, and the coating solution may not have a desired thickness. For this reason, the environmental temperature is detected by the temperature detecting means, or the viscosity of the coating liquid is detected by the viscosity detecting means, and the contact pressure between the second blade 140 and the conveying belt 28, the pressure is detected according to the detected temperature and viscosity. It is effective to change the tangent angle.

  Next, a sixth embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st thru | or 5th embodiment, and description is abbreviate | omitted.

  As shown in FIG. 15, in this embodiment, a belt cleaning unit 152 is disposed below the peeling claw 40. The belt cleaning unit 152 includes a blade 49 that abuts on a portion of the transport belt 28 wound around the drive roll 24 and scrapes off ink or the like attached to the transport belt 28.

  An oil application unit 154 is disposed below the drive roll 24. The oil application unit 154 is rotatably supported by the case 156, the belt-like web 66, the case 156, and the feed shaft 68 wound around one end side in the longitudinal direction of the web 66, and the case 156. The web 66 is wound around the other end of the web 66 in the longitudinal direction, and is press-contacted so as to be rotatably supported by the case 156 and press the web 66 against the portion of the conveyor belt 28 wound around the drive roll 24. A roll 90 and pinch rolls 92 and 94 that are rotatably supported by the case 156 and apply tension to the web 66 are provided.

  The feed shaft 68, the pinch roll 92, the pressure contact roll 90, the pinch roll 94, and the take-up shaft 88 are arranged in the order described from the upstream side to the downstream side in the moving direction of the web 66, and the pinch roll 92, the pressure contact roll 90, the pinch roll 94 are arranged in the order described from the upstream side to the downstream side in the rotation direction of the conveyor belt 28, and the web 66 is stretched. The web 66 is impregnated with silicone oil.

  Here, the take-up shaft 88 is driven by a motor (not shown). When the take-up shaft 88 is rotated by the drive of the motor, the web 66 is fed from the feed shaft 68, and a minute amount is obtained. Each is conveyed to the winding shaft 88 side. As a result, silicone oil is applied to the conveyor belt 28 at the nip portion between the pressure contact roll 90 and the drive roll 24, and a silicone oil film is formed on the conveyor belt 28. On the other hand, the ink ejected from the recording head 32 is a water-based ink. For this reason, when ink adheres to the transport belt 28 by unnecessary ink discharge at the time of ink mist or paper jam, or a dummy jet discharged onto the transport belt 28, the repellency of the silicone oil film on the transport belt 28 is reduced. The ink aggregates due to the water effect. Therefore, the force of ink adhering to the conveyance belt 28 can be suppressed, and when the conveyance belt 28 is cleaned by the blade 49, the ink is easily separated from the conveyance belt 28. Here, since the dummy jet is performed at a short cycle such as once every several tens of seconds in order to prevent thickening of the ink in the recording head 32, the dummy jet is always on the transport belt 28 as in the present embodiment. It is effective to form a silicone oil film.

  The case 156 is partitioned into a web storage chamber 156B and a waste liquid recovery chamber 156C by a partition wall 156A. The web accommodating chamber 156B accommodates a feed shaft 68, a pinch roll 92, a pressure contact roll 90, a pinch roll 94, a take-up shaft 88, and a web 66 stretched around these. Further, the waste liquid recovery chamber 156C is provided directly below the blade 49, and the upper part is an opening. The ink scraped off by the blade 49 is dropped into the waste liquid recovery chamber 156C. Further, an absorber 157 is spread on the bottom of the waste liquid recovery chamber 156C, and absorbs the liquid dropped from the blade 49.

  Also, as shown in FIGS. 16A and 16B, the oil application unit 154 can be attached to and detached from the apparatus main body by an attaching / detaching mechanism 158. The attachment / detachment mechanism 158 includes a guide mechanism 160 and a lock mechanism 162.

  The guide mechanism 160 includes a guide groove 164 and guide ribs 166. The guide grooves 164 are provided on the frame F of the apparatus main body standing on both ends in the width direction of the conveyor belt 28, and extend substantially horizontally from one horizontal end portion of the frame F to below the drive roll 24. . The guide ribs 166 are provided on both end surfaces of the case 156 in the longitudinal direction, extend substantially horizontally, and can slide in the guide grooves 164. The guide groove 164 extends in a tapered shape at one end portion in the horizontal direction of the frame F, so that the guide rib 166 can be easily inserted into the guide groove 164.

  The lock mechanism 162 includes a lock lever 168, a tension coil spring 170, a stopper 172, and studs 174 and 175. The lock lever 168 is rotatably attached above the guide groove 164 of the frame F. The lock lever 168 is provided with a pivot 168A at the center in the longitudinal direction and a claw 168B at one end in the longitudinal direction.

  The tension coil spring 170 is disposed on the inner side and the upper side of the rotation fulcrum 168A, and is hooked on the other end portion in the longitudinal direction of the lock lever 168 and the frame F. The stopper 172 is a pin erected on the inner side and the upper side of the rotation support point 168A of the frame F. The stopper 172 is a longitudinal direction of the lock lever 168 urged clockwise by the tension coil spring 170 in FIG. The end is brought into contact with the stopper 172. In this state, the lock lever 168 is substantially horizontal and the claw 168 is directed downward.

  The stud 174 is provided on the upper side of the guide ribs 166 on both end faces in the longitudinal direction of the case 156. When the case 156 is pushed into the apparatus with the guide rib 166 fitted in the guide groove 164, the stud 174 is formed. The lock lever 168 is brought into contact with the claw 168B, and the one end side in the longitudinal direction of the lock lever 168 is pushed up against the urging force of the tension coil spring 170.

  The stud 175 is provided on the inner side and upper side of the guide groove 164 of the frame F, and restricts the movement of the case 156 to the inner side of the device. When the case 156 is pushed to a position where it comes into contact with the stud 175, the stud 174 passes through the claw 168B of the lock lever 168, and one end in the longitudinal direction of the lock lever 168 is lowered by the urging force of the tension coil spring 170. And the stud 174 engage with each other. In this state, the pressure contact roll 90 and the drive roll 24 are in pressure contact via the web 66 and the conveyor belt 28.

  By the way, as shown in FIG. 17A, when the web 66 is brought into contact with the conveyance belt 28 on the downstream side by a distance L from the drive roll 24, the conveyance belt 28 is interposed between the drive roll 24 and the web 66. A compressive force acts on the conveyor belt 28 to contract. In addition, as shown in FIG. 17B, when the blade 49 is brought into contact with the transport belt 28 at a distance L upstream from the drive roll 24, the transport belt 28 is interposed between the drive roll 24 and the blade 49. A tensile force acts on the conveyor belt 28 and the conveyor belt 28 extends.

  The extension amount of the conveyor belt 28 due to such a compressive force or tensile force varies depending on the load fluctuation of the web 66 or the blade 49, but the fluctuation of the extension amount is transmitted to a portion in the print area SE of the conveyor belt 28, Causes adverse effects such as image unevenness.

  On the other hand, in the present embodiment, both the blade 49 and the web 66 are in contact with the portion of the conveyance belt 28 wound around the drive roll 24, and the blade 49 and the web 66 are in contact with the conveyance belt 28. Thus, a shearing force acts, and the conveying belt 28 extends due to the shearing force. Here, the extension amount of the conveying belt 28 due to the shearing force is extremely small as compared with the above-described compression force and tensile force, and the fluctuation of the extension amount does not adversely affect the image quality.

  In this embodiment, the belt cleaning unit 152 and the oil application unit 154 are separate units. However, as shown in FIG. 18, the maintenance of the oil application unit 154 and the belt can be performed by using the same unit. Maintenance of the cleaning unit 152 can be performed together.

  In this embodiment, the application liquid is applied using the web 66. However, as shown in FIG. 19, the application roll 102 that can absorb the liquid is impregnated with the application liquid, and the oil application roll 102 is conveyed. You may carry out by the method made to contact | abut to the belt 28. FIG. In this case, it is desirable to provide an oil blade 104 that regulates the coating liquid applied to the conveyor belt by the oil application roll 102 to a desired thickness.

  Next, a seventh embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st thru | or 6th embodiment, and description is abbreviate | omitted.

  As shown in FIG. 20, in this embodiment, only the blade 49 abuts on the portion of the conveyor belt 28 that is wound around the drive roll 24, and the contact position between the web 66 and the conveyor belt 28 is the conveyor belt 28. It is set downstream by a distance L from the downstream end of the portion wound around the drive roll 24.

  By the way, in the vicinity of the drive roll 24, the mechanical relationship shown by the following formula (*) is established.

ΔL = ΔF · L / (E · t · w) (*)
However, ΔL: contraction amount (mm) of the conveying belt 28 within the range of the distance L
ΔF: Fluctuation amount of load that the conveyor belt 28 receives from the oil application unit 154 (N)
E: Longitudinal elastic modulus (N / mm ² ) of the conveyor belt 28
t: thickness of transport belt 28 (mm)
w: width of transport belt 28 (mm)
Here, it has been experimentally confirmed that when the shrinkage amount ΔL is 0.01 mm or more, the unevenness of the image becomes a level at which it can be visually confirmed. For this reason, by satisfying the following expression (A) for the distance L, it is possible to suppress image unevenness to a level that is not visually confirmed.

0 ≦ L <0.01 · E · t · w / ΔF (A)
For example, when the conveyor belt 28 is a PI belt having a longitudinal elastic modulus E of 4000 N / mm ² , a thickness t of 0.075 mm, and a width w of 350 mm, and the load variation ΔF is 30 N, the distance L By making the value smaller than 35 mm, image unevenness can be suppressed to a level that cannot be visually confirmed.

  In addition, as a case where the load applied to the conveyor belt 28 from the belt cleaning unit 152 or the oil application unit 154 fluctuates, for example, the blade 49 after the dummy jet is performed on the conveyor belt 28 is used as the ink on the conveyor belt 28. And the moment when the web 66 is finely fed. In the previous example, the blade 49 gets wet with a large amount of ink, and the frictional resistance with the conveying belt 28 decreases, so that the load fluctuates. In the later example, the load fluctuates because the frictional resistance with the conveyor belt 28 differs between when the web 66 is moved and when it is stopped.

  In this embodiment, the belt cleaning unit 152 is brought into contact with the portion of the transport belt 28 that is wound around the drive roll 24, and the contact position between the oil application unit 154 and the transport belt 28 is wound around the drive roll 24. As shown in FIG. 21, the oil application unit 154 is brought into contact with the portion of the conveyor belt 28 wound around the drive roll 24, and the belt cleaning unit 152 and the conveyor belt 28 are in contact with each other. The position may be set upstream by a distance L from the upstream end of the portion of the conveyor belt 28 that is wound around the drive roll 24.

  In the first to seventh embodiments, the present invention has been described by taking an inkjet recording apparatus as an example. However, the present invention is not limited to an inkjet 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.

  In addition, the “conveying member” in the droplet discharge apparatus of the present invention includes a wide range of members as long as they hold and convey a recording medium. For example, a drum that rotates while holding the recording medium on a peripheral surface, a table that reciprocates while holding the recording medium, and the like are included.

  Furthermore, in the first to seventh 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 an enlarged cross-sectional view illustrating a conveyance belt provided in the ink jet recording apparatus according to the 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 2nd Embodiment of this invention. It is a side view which shows the outline of the printing part of the inkjet recording device of 3rd Embodiment of this invention. It is a side view which shows the outline of the printing part of the inkjet recording device of 4th Embodiment of this invention. It is a sectional side view which shows the belt cleaning and oil application unit with which the inkjet recording device of 5th Embodiment of this invention was equipped. FIG. 9 is an exploded perspective view (A) and a top view (B) showing a first blade and a second blade provided in the belt cleaning and oil application unit of FIG. 8. FIG. 9 is a side sectional view showing a modification of the belt cleaning / oil application unit of FIG. 8. It is the exploded perspective view (A) and top view (B) which show the modification of the 1st blade and 2nd blade with which the belt cleaning and oil application unit of FIG. 10 was equipped. It is a top view which shows the modification of the 1st blade and 2nd blade with which the belt cleaning and oil application unit of FIG. 8 was equipped. (A) is a sectional side view showing a modification of the belt cleaning and oil application unit of FIG. 8, and (B) is a first blade and a second blade provided in the belt cleaning and oil application unit of (A). It is a figure which shows typically the formation method of these. (A) is a sectional side view showing the belt cleaning and oil application unit of FIG. 8, and (B) is a sectional side view showing a modification of the belt cleaning and oil application unit of (A). It is a sectional side view which shows the belt cleaning unit and oil application unit with which the inkjet recording device of 6th Embodiment of this invention was equipped. (A), (B) is a side view which shows the mechanism which attaches or detaches the oil application unit of FIG. 15 to an apparatus main body. (A) is a sectional side view showing a modification of the arrangement of the oil application unit of FIG. 15, and (B) is a sectional side view showing a modification of the arrangement of the belt cleaning unit of FIG. FIG. 16 is a side sectional view showing a modification of the belt cleaning unit and the oil application unit of FIG. 15. FIG. 16 is a side sectional view showing a modification of the oil application unit of FIG. 15. It is a sectional side view which shows the belt cleaning unit and oil application unit with which the inkjet recording device of 7th Embodiment of this invention was equipped. FIG. 22 is a side sectional view showing a modified example of the arrangement of the belt cleaning unit and the oil application unit of FIG. 21.

Explanation of symbols

12 Inkjet recording device (droplet ejection device)
24 Drive roll 28 Conveying belt (conveying member)
32 Inkjet recording head (droplet ejection head)
49 Blade (cleaning means)
66 Web (coating means)
102 Oil application roll (application means)
112 Oil application roll (application means)
138 First blade (cleaning means)
140 Second blade (coating means, absorber)
150 Core material (flow path)
N1 nip part (coating means, first contact part)
N2 nip (cleaning means, second contact part)
P paper (recording medium)
S slit (flow path)

Claims (11)

A droplet discharge head for discharging droplets;
A conveying member that holds a recording medium and conveys the recording medium to face the droplet discharge head;
Cleaning means for cleaning the conveying member;
Application means for applying an application liquid having a property of repelling liquid discharged from the droplet discharge head to the transport member;
I have a,
The surface tension γ _{0 of the} coating liquid, the critical surface tension γ _{b of} the conveying member, and the surface tension γ _{i of the} liquid discharged from the droplet discharge head satisfy the following expressions (1) and (2). A droplet discharge device.
γ ₀ <γ _b (1)
γ ₀ <γ _i (2) A droplet discharge head for discharging droplets;
A conveying member that holds a recording medium and conveys the recording medium to face the droplet discharge head;
Cleaning means for cleaning the conveying member;
Application means for applying an application liquid having a property of repelling liquid discharged from the droplet discharge head to the transport member;
Have
Droplet discharge device you wherein the liquid discharged from the droplet discharge head is a liquid water-based ink, the coating liquid has water repellency. The droplet liquid aqueous ink ejected from the ejection head, a liquid ejecting device according to claim 1, wherein the coating liquid is characterized in that a liquid having water repellency. The conveying member is a rotating body that holds and rotates a recording medium;
The application unit is disposed downstream in the rotation direction when the recording medium of the conveying member is conveyed from the cleaning unit and upstream in the rotation direction when the recording medium of the conveyance member is conveyed from the droplet discharge head. The droplet discharge device according to claim 1, wherein the droplet discharge device is provided. Having a web that absorbs the coating liquid and moves while contacting the conveying member a plurality of times;
The application means is a first contact portion that contacts the conveying member on the upstream side in the moving direction of the web and applies the coating liquid to the conveying member.
5. The liquid droplet according to claim 4, wherein the cleaning unit is a second contact portion that contacts the transport member on the downstream side in the moving direction of the web and sucks the liquid adhering to the transport member. Discharge device.   The droplet discharge device according to claim 4, wherein the cleaning unit and the coating unit are integrated. The cleaning means is a first blade abutting against the conveying member;
7. The liquid droplet ejection according to claim 6, wherein the coating unit is a second blade that is arranged in parallel with the first blade and forms a flow path through which the coating liquid flows between the first blade and the first blade. apparatus. The cleaning means is a first blade abutting against the conveying member;
The liquid droplet ejection apparatus according to claim 6, wherein the coating unit is an absorber bonded to the first blade and absorbing the coating liquid. The conveying member is an endless belt;
A driving roll around which the belt is wound;
The liquid droplet ejection apparatus according to claim 1, wherein the cleaning unit and the coating unit abut on a portion of the belt wound around the drive roll. The conveying member is an endless belt;
A driving roll around which the belt is wound;
One of the cleaning means and the application means abuts on a portion of the belt wound around the drive roll,
A distance L between a position where the other of the cleaning unit and the coating unit abuts on the belt and a portion of the belt wound around the drive roll satisfies the following expression (A). The liquid droplet ejection apparatus according to claim 1.
0 ≦ L <0.01 · E · t · w / ΔF (A)
However, ΔF: Fluctuation amount (N) of load that the belt receives from the other of the cleaning means and the application means
E: Longitudinal elastic modulus of the belt (N / mm ² )
t: thickness of the belt (mm)
w: width of the belt (mm)   11. The droplet discharge device according to claim 1, wherein at least one of the application unit and the cleaning unit is detachable from the apparatus main body.

Images