JP2008044721A - Droplet discharge device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress cleaning failure of a carrying belt by a blade. <P>SOLUTION: Silicone oil O having characteristics to repel ink such as silicone oil is applied to the carrying belt 28, so as to suppress increase in adhesion between ink I and the carrying belt 28. In addition, a hot wire 50 is provided on a plate face 49B of the blade 49 facing the upstream side in the belt rotating direction, and the silicone oil O on the plate face 49B is heated. Thus, the kinematic viscosity of the silicone oil O on the plate face 49B is reduced and the flowability of the silicone oil O is enhanced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a droplet discharge device that discharges liquid from a droplet discharge head.

  In an ink jet printer as a droplet discharge device, silicone oil is applied to a conveyor belt as a rotating body and a silicone oil film is interposed between the conveyor belt and the ink, thereby increasing the adhesion between the ink and the conveyor belt. It has been devised to lower the ink and improve the ink scraping performance by the blade (see, for example, Patent Document 1).

In this ink jet printer, the ink scraping performance from the conveyor belt by the blade is improved, but if the fluidity of the oil on the blade is poor, the ink tends to stay on the blade. The ink scraping performance from the ink may deteriorate.
Japanese Patent No. 28268891

  The present invention has been made in consideration of the above facts, and an object thereof is to suppress poor cleaning of a rotating body by a blade.

  The liquid droplet ejection apparatus according to claim 1, wherein a liquid droplet ejection head that ejects liquid in droplets, a rotary body that faces the liquid droplet ejection head, and the counter member that contacts the rotary body and cleans the opposing member And a coating member for coating the rotating body with a coating liquid having a property of repelling the liquid ejected from the liquid droplet ejection head, and a heating means for heating the coating liquid on the blade. Features.

  In the droplet discharge device according to the first aspect, the blade contacts the rotating body facing the droplet discharge head to clean the rotating body. The rotating body is coated with a coating liquid by a coating member to form a coating liquid film. 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, an increase in the adhesion force between the liquid discharged from the droplet discharge head and the rotating body can be suppressed, so that when the rotating body is cleaned by the blade, the liquid discharged from the droplet discharge head and attached to the rotating body. However, it peels easily from the rotating body.

  Here, the coating liquid on the blade is heated by the heating means, and the kinematic viscosity decreases. This increases the fluidity of the coating liquid on the blade. Along with this, it is possible to suppress stagnation of the liquid scraped from the rotating body by the blade on the blade, and it is possible to suppress a decrease in the scraping performance of the liquid from the rotating body by the blade. Therefore, compared with the case where this configuration is not provided, it is possible to suppress the cleaning failure of the rotating body by the blade.

  The droplet discharge device according to claim 2 is the droplet discharge device according to claim 1, wherein the heating unit is disposed away from a contact portion of the blade with the rotating body on a side opposite to the rotating body. It is characterized by that.

  In the droplet discharge device according to claim 2, since the heating means is arranged away from the contact portion of the blade with the rotating body on the side opposite to the rotating body, heat generated by the heating means is generated around the contact portion between the blade and the rotating body. It is difficult to transmit to the coating liquid, and it is possible to suppress a decrease in the surface tension of the coating liquid around the contact portion between the blade and the rotating body. Accordingly, a stable layer of the coating liquid applied to the rotating body by the applying member can be formed around the contact portion between the blade and the rotating body, as compared with the case where the present configuration is not provided.

  Therefore, the liquid discharged from the droplet discharge head and adhering to the rotating body enters the contact portion between the blade and the rotating body, and slips between the blade and the rotating body to suppress poor cleaning of the rotating body by the blade. it can.

  A droplet discharge device according to claim 3 is the droplet discharge device according to claim 1 or 2, further comprising cooling means for cooling a contact portion of the blade with the rotating body. And

  In the droplet discharge device according to claim 3, the surface tension of the coating liquid around the contact portion of the blade with the rotating body is reduced by cooling the contact portion of the blade with the rotating body by the cooling unit. It is suppressed. Accordingly, a stable layer of the coating liquid applied to the rotating body by the applying member can be formed around the contact portion between the blade and the rotating body as compared with the case where the present configuration is not provided.

  Therefore, the cleaning failure of the rotating body by the blade, in which the liquid discharged from the droplet discharge head and attached to the rotating body enters the contact portion between the blade and the rotating body and passes between the blade and the rotating body, can be suppressed. .

  The droplet discharge device according to claim 4 is the droplet discharge device according to any one of claims 1 to 3, wherein the heating means is a heating element provided on the blade. It is characterized by that.

  In the droplet discharge device according to the fourth aspect, the coating liquid on the blade is heated by the heating element provided on the blade, and the fluidity of the coating liquid on the blade is increased. Here, since the heating element is provided on the blade, the heat generated by the heating element is more easily transferred to the coating liquid on the blade and the heating value of the heating element is set lower than when the heating element is arranged away from the blade. it can.

  The droplet discharge device according to claim 5 is the droplet discharge device according to claim 4, wherein the heating element is provided on a plate surface of the blade facing the upstream side in the rotation direction of the rotating body. It is characterized by.

In the droplet discharge device according to claim 5, the coating liquid on the blade is heated by the heating element provided on the plate surface facing the upstream side in the rotational direction of the rotating body of the blade, and the coating liquid on the blade is heated. Increases fluidity. Here, by providing the heating element on the plate surface facing the upstream side of the rotation direction of the rotating body of the blade, the heating element comes into contact with the coating liquid on the blade. Directly communicate. Therefore, as compared with the droplet discharge device according to the fourth aspect, the heat generated by the heating element is easily transmitted to the coating liquid on the blade, and the heating value of the heating element can be set lower. In addition, since the heating element is provided on the blade plate surface, the manufacturing becomes easier as compared with the case where the heating element is provided inside the blade.

  The droplet discharge device according to claim 6 is the droplet discharge device according to any one of claims 1 to 3, wherein the heating unit is upstream of the blade in the rotation direction of the rotating body. The heating element is arranged to face the plate surface facing the side and generates heat toward the plate surface, and a heat insulating member is provided between the heating element and the rotating body.

  In the droplet discharge device according to claim 6, the heating element is disposed opposite to the plate surface facing the upstream side in the rotation direction of the rotating body of the blade, and generates heat toward the plate surface, thereby generating heat on the blade. The coating solution is heated. Here, a heat insulating member between the heating element and the rotating body is provided, heat transfer from the heating element to the periphery of the contact portion between the blade and the rotating body is suppressed, A decrease in the surface tension of the coating solution is suppressed.

  As a result, a stable layer of the coating liquid applied to the rotating body by the coating member can be formed around the contact portion between the blade and the rotating body as compared with the case where the present configuration is not provided. Further, it is possible to suppress the cleaning failure of the rotating body by the blade, in which the liquid discharged from the droplet discharge head and attached to the rotating body enters between the blade and the rotating body and passes between the blade and the rotating body. In addition, since the blade is not provided with a heating element, a conventionally known blade can be used, and a known heating element can also be used, so that the manufacturing cost can be reduced compared to the case where a heating element is provided on the blade. .

  The droplet discharge device according to claim 7 is the droplet discharge device according to any one of claims 1 to 6, wherein the temperature detection means detects the temperature of the surface of the blade, and And a first control means for controlling the heating means in accordance with the temperature detected by the temperature detection means.

  In the droplet discharge device according to the seventh aspect, the temperature of the surface of the blade is detected by the temperature detecting means, and the first control means controls the heating means in accordance with the temperature detected by the temperature detecting means. This makes it possible to maintain the coating liquid on the blade in an appropriate state.

  A droplet discharge device according to an eighth aspect of the present invention is the droplet discharge device according to any one of the first to seventh aspects, wherein the liquid droplet discharge head discharges liquid that is discharged during preliminary discharge. It has the 2nd control means which controls the above-mentioned heating means according to quantity.

  In the droplet discharge device according to the eighth aspect, the second control unit controls the heating unit in accordance with the amount of liquid discharged by the droplet discharge head during preliminary discharge. This makes it possible to maintain the coating liquid on the blade in an appropriate state according to the amount of liquid discharged from the droplet discharge head and attached to the rotating body.

  The droplet discharge device according to claim 9 is the droplet discharge device according to any one of claims 1 to 8, wherein the amount of the coating liquid applied by the coating member to the rotating body. And a third control means for controlling the heating means.

  In the droplet discharge device according to the ninth aspect, the third control unit controls the heating unit in accordance with the amount of the coating liquid applied to the rotating body by the coating member. This makes it possible to maintain the coating liquid on the blade in an appropriate state according to the amount on the blade.

  Since the present invention has the above configuration, it is possible to suppress poor cleaning of the rotating body by the blade.

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In addition, the rotation direction (hereinafter referred to as the belt rotation direction) of the conveyance belt 28 as a rotating body is indicated by an arrow A in the drawing.

  FIG. 1 shows an ink jet recording apparatus 12 as a droplet discharge apparatus 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). , Cyan (C), and black (K), four ink jet recording heads (hereinafter referred to as recording heads) 32 as liquid droplet ejection heads corresponding to the four colors, respectively, are arranged along the transport direction. Images can be recorded.

  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.

  Each of the recording heads 32 performs ejection of ink droplets (so-called preliminary ejection) unrelated to image formation for the purpose of preventing nozzle clogging or the like between pages or before the start of printing. To 28.

  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 upstream of the recording head array 30 in the belt rotation direction. 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 in the belt rotation direction, and the sheet P is separated 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 claw 40 in the paper transport direction, and is discharged to a paper discharge tray 46 provided at the top of the housing 14. .

  A belt cleaning unit 48 is disposed downstream of the peeling claw 40 in the belt rotation direction. 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 ink adhering to the transport belt 28. The blade 49 is scraped off from the transport belt 28 by the blade 49. And a collection box 51 for collecting the 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.

  Further, a grounded static eliminating roll 62 is disposed on the downstream side of the belt cleaning unit 48 in the belt rotation direction. The neutralizing roll 62 is driven while sandwiching the conveyance belt 28 between the grounded driven roll 27 and removes the electric charge on the conveyance belt 28.

  Further, the oil application unit 64 and the backup plate 66 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 64 faces the outer peripheral surface of the conveyor belt 28, and the backup plate 66 is in contact with the inner peripheral surface of the conveyor belt 28.

  The oil application unit 64 includes a case 68, an oil application roll 70 as an application member that is rotatably supported by the case 68, and an oil blade 72 supported by the case 68. The oil application roll 70 is pressed against the backup blade 66 with the conveyance belt 28 interposed therebetween, and rotates following the conveyance belt 28. The oil application roll 70 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. 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 paper jam or a dummy jet discharged onto the transport belt 28, the water repellent effect of the silicone oil film on the transport belt 28 Ink aggregates. Accordingly, it is possible to suppress an increase in the force with which the ink adheres to the conveyance belt 28, 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.

  The oil application roll 70 may be a drive roll that is driven to rotate by a motor, instead of a driven roll driven by the conveyor belt 28. In this case, the oil application roll 70 can be prevented from slipping with respect to the conveyor belt 28.

  The oil blade 72 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 70, and scrapes off excess silicone oil applied to the conveyor belt 28. The film thickness is set to a predetermined thickness. The oil blade 72 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 74 such as a sponge is spread on the bottom of the case 68, and the absorbing member 74 absorbs the silicone oil scraped from the conveying belt 28 by the oil blade 72.

  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 oil application roll 70 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 can be wound.

  Further, as described above, silicone oil is used as the liquid (hereinafter referred to as application liquid) applied to the conveyor belt 28 by the oil application roll 70, 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 wet on the conveyor belt 28, the relationship of the following formula (A) 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 (A)
Further, in order to give the coating liquid T water repellency, the relationship of the following formula (B) is required. However, the surface tension of the ink I is γ _i .

γ ₀ <γ _i (B)
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.

  By the way, as shown in FIG. 5A, the blade 49 is a rectangular plate material, and the entire corner (edge) 49A on one end side in the width direction is brought into contact with the outer peripheral surface 28A of the conveying belt 28 to convey it. The ink I and the silicone oil O adhering to the belt 28 are scraped off. Further, the blade 49 is installed so as to be inclined downward from one end side in the width direction to the other end side. For this reason, the ink I and the silicone oil O scraped off from the conveying belt 28 by the edge 49A of the blade 49 flow down to the other end in the width direction of the blade 49 by their own weight, and are collected from the other end in the width direction of the blade 49. Fall to 51.

  Here, as shown in FIG. 5 (B), the heat wire 50 as a heating means and a heating element is attached to or embedded in the plate surface 49B of the blade 49 facing the upstream side in the belt rotation direction. Or formed by vapor deposition or the like. The hot wire 50 is a member that generates heat when electricity is passed, and one end and the other end are connected to a power source (not shown), and the wave surface 50B extends from one end to the other end in the longitudinal direction of the plate surface 49B. It extends while bending into a shape.

  For this reason, when a current is supplied from the power source to the heat wire 50, a wave-like heat generating portion is formed on the plate surface 49B, and the liquid such as silicone oil O and ink I on the plate surface 49B is heated. As a result, the kinematic viscosity of the silicone oil O on the plate surface 49B decreases and the fluidity of the silicone oil O increases, so that the ink I on the plate surface 49B hardly stays on the blade 49.

  In addition, as the heat wire 50, a conventionally known member that generates heat by flowing electricity, for example, a wire-like or strip-like alloy wire for electric heating, an alloy foil for electric heating, or the like made of nickel-chrome-based metal or iron-chromium-based metal is used. Can be used.

  The blade 49 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, and the like, similar to the blade 72 for oil.

  Here, the edge 49A of the blade 49 is oil-cooled by the silicone oil O that is scraped off from the conveying belt 28 by the edge 49A and is heated by the hot wire 50, so that the temperature becomes lower than the plate surface 49B, and the surface tension is reduced. Kept high. For this reason, a layer of silicone oil O is stably formed around the edge 49A. This makes it difficult for the ink I to accumulate around the edge 49A and improves the cleaning performance.

Note that the silicone oil O has a kinematic viscosity of 100 mm ² / s at room temperature (25 ° C.) (for example, silicone oil KF96-100CS: manufactured by Shin-Etsu Chemical Co., Ltd., see the tables in FIGS. 6A and 6B). The blade 49 is made of polyurethane, and the heat wire 50 having the above-described configuration is formed of a nickel-chrome alloy wire for electric heating, and a current is passed through the heat wire 50 so that the plate surface 49B of the blade 49 is 70 ° C. It was confirmed that the kinematic viscosity of the silicone oil O on the plate surface 49B dropped to about 50 mm ² / s, which is about half, and the fluidity of the silicone oil O increased to a sufficient level.

Incidentally, as shown in the table of FIG. 6A, the above-described silicone oil having a kinematic viscosity of 100 mm ² / s at room temperature or a silicone oil having a kinematic viscosity of 50 mm ² / s at room temperature (for example, silicone oil KF96). -50CS: Silicone oil having a lower kinematic viscosity at room temperature than that of Shin-Etsu Chemical Co., Ltd. Is not suitable for use because it is highly volatile, has a low flash point, and hardly adheres to the conveyor belt 28.

  For this reason, the silicone oil O having a low kinematic viscosity that can exhibit sufficient fluidity at room temperature cannot be used. As described above, the silicone oil O on the blade 49 is heated to reduce the viscosity. The silicone oil O exhibits sufficient fluidity.

  In addition, as shown in the table of FIG. 6B, the viscosity of the oil such as silicone oil decreases as the temperature increases. However, if the temperature becomes too high, the gel is caused by deformation of the blade 49, material change, or thermal oxidation of the oil. There may be problems such as conversion. For this reason, the temperature of the plate surface 49B of the blade 49 may be set in consideration of the properties of the blade 49, the conveyor belt 28, and oil. For example, in the case of the above-described silicone oil KF96-50CS and silicone oil KF96-100CS, about 50 to 100 ° C. is preferable in consideration of deformation of the blade 49 due to heat, material change, chemical stability, and the like.

  In this embodiment, since the heat ray 50 is formed on the plate surface 49B of the blade 49, unevenness is formed on the plate surface 49B. Depending on the size of the unevenness, the flow of the silicone oil O on the plate surface 49B may be caused. It will be disturbed. Therefore, as shown in FIG. 7, when the heat ray 50 protrudes from the plate surface 49B, the end portion 50A on the edge 49A side of the heat ray 50 is formed in a tapered shape, and the heat ray 50 and the plate surface 49B form silicone. It is desirable to prevent the corner L where the oil O is accumulated from being formed.

  In the present embodiment, the heating wire 50 as the heating means is provided on the blade 49, so that the heat generated by the heating means is less than the silicone oil on the blade 49 compared to the case where the heating means is arranged away from the blade 49. It becomes easy to be transmitted to O, and the calorific value of the heating means can be set low. Further, in the present embodiment, the heat wire 50 is formed on the plate surface 49B of the blade 49, whereby the heat wire 50 can be directly caused to the silicone oil O, and the heat generated by the heat wire 50 is easily transmitted by the silicone oil O. As shown in FIG. 8, the heat ray 50 may be embedded in the blade 49. In this case, unevenness cannot be formed on the plate surface 49B by the heat ray 50, so that the flow of the silicone oil O on the plate surface 49B is not hindered.

  Further, in the present embodiment, as shown in FIG. 5B, the hot wire 50 is provided so that the end of the hot wire 50 covers the edge 49A. However, as shown in FIG. 9, the hot wire 50 is predetermined from the edge 49A. The distance D may be separated to the opposite side of the conveyor belt 28. In this case, the heat generated by the heat ray 50 is less likely to be transmitted to the silicone oil O forming a layer around the edge 49A, and the decrease in surface tension due to the temperature drop of the silicone oil can be suppressed. A layer of silicone oil O can be formed.

  Further, in order to stably form the silicone oil O layer around the edge 49A, a cooling means for cooling the periphery of the edge 49A may be provided. As an example of this cooling means, a Peltier element 52 shown in FIGS. As shown in FIG. 10A, the Peltier element 52 is attached to the end of the blade surface 49C facing the downstream side in the belt rotation direction on the conveying belt 28 side in the width direction of the plate surface 49C. As shown in FIG. 3, the drive roll 24 may be hollow and attached to the inside of the drive roll 24. Accordingly, even when the cooling effect of the edge 49A by the silicone oil O before being heated by the heat ray 50 is scraped off from the conveying belt 28 by the edge 49A, the edge 49A can be reliably cooled, and at the same time, the conveying belt 28 is also reliably Therefore, the deterioration of the conveyor belt 28 due to heat is 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. 11, in the present embodiment, a heater 54 as a heating unit is disposed to face a plate surface 49 </ b> B of the blade 49, and the silicone oil O on the blade 49 is caused by heat generated by the heater 54. Heated. As a result, as in the first embodiment, the kinematic viscosity of the silicone oil O on the blade 49 decreases, and the fluidity of the silicone oil O increases.

  A heat insulating plate 56 is disposed between the heater 54 and the transport belt 28 as a heat insulating member that separates the heater 54 and the transport belt 28. The heat insulating plate 56 suppresses heat transfer from the heater 54 to the conveyor belt 28 and the edge 49 </ b> A of the blade 49. As a result, the silicone oil O immediately before and after being scraped from the conveyor belt 28 by the edge 49A is suppressed from being heated by the heater 54, and a layer of the silicone oil O is stably formed around the edge 49A.

  Incidentally, the temperature of the plate surface 49B of the blade 49 is detected by the temperature sensor 58, and the heater 54 is controlled according to the detection result of the temperature sensor 58 by the CPU 60 as the first control means. Hereinafter, this control method will be described with reference to the flowchart of FIG.

  When the power supply of the inkjet recording apparatus 12 is turned on, the processing routine is started and the process proceeds to Step 1. In step 1, it is determined whether or not a print job has been received. If the determination is affirmative, the process proceeds to step 2. If the determination is negative, step 1 is repeated. In step 2, the heater 54 is turned on, and the process proceeds to step 3.

  In step 3, it is determined whether or not the temperature detected by the temperature sensor 58 is equal to or higher than the set temperature. If the determination is negative, the process proceeds to step 2, and the heater 54 is kept on. Move to 4. In step 4, the heater 54 is turned off and the process proceeds to step 5.

  In step 5, printing is started and the process proceeds to step 6. In Step 6, it is determined whether or not the printing is finished. If the determination is negative, the process proceeds to Step 3 and Steps 3 to 6 are repeatedly executed. If the determination is affirmative, the processing routine is ended.

  That is, in the present embodiment, when the temperature of the plate surface 49B of the blade 49 reaches the set temperature, the heater 54 is turned off. As a result, power consumption can be suppressed, excessive temperature rise of the blade 49 can be prevented, and deformation of the blade 49 and changes in material due to heat, thermal oxidation of the silicone oil O, and the like can be prevented.

  In the present embodiment, the heater 54 is used as the heating means, but a heat source lamp or the like may be used.

  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 FIGS. 13A and 13B, in this embodiment, a blade adjustment mechanism 82 for adjusting the position of the coating amount adjustment blade 72 is provided. The blade adjustment mechanism 82 includes a moving body 108, a support member 86, a cam 110, and a pair of tension coil springs 90.

  The moving body 108 is a trapezoidal member when viewed in the belt width direction, and the surface facing the conveyor belt 28 is inclined from the upstream side to the downstream side in the belt rotation direction from the opposite conveyor belt 28 side to the conveyor belt 28 side. Since the coating amount adjustment blade 72 is attached to the inclined surface on the downstream side in the belt rotation direction, the downstream side in the belt rotation direction of the coating amount adjustment blade 72 comes into contact with the transport belt 28. ing.

  The support member 86 is a U-shaped member as viewed in the belt width direction, which supports the movable body 108 so as to be able to contact and separate from the conveyance belt 28. The cam 110 is a disc-shaped eccentric cam disposed between the moving body 108 and the support member 86. Further, the pair of tension coil springs 90 is disposed on both sides of the cam 110 between the moving body 108 and the support member 86, and urges the moving body 108 toward the anti-conveying belt 28, It is pressed against the surface.

  For this reason, when the cam 110 rotates, the moving body 108 moves to the conveying belt 28 side against the urging force of the tension coil spring 90, and moves to the counter-conveying belt 28 side by the urging force of the tension coil spring 90.

  As shown in FIG. 13A, the application amount adjusting blade 72 is moved to the conveying belt 28 side by the movement of the moving body 108 toward the conveying belt 28 by the rotation of the cam 110, and the conveying belt of the applying amount adjusting blade 72 is moved. The amount of biting into 28 is increased. Further, as shown in FIG. 13B, the application amount adjustment blade 72 is moved to the anti-conveyance belt 28 side by the movement of the moving body 108 to the anti-conveyance belt 28 side by the rotation of the cam 110, and the application amount adjustment blade. The amount of biting 72 into the conveyor belt 28 is reduced.

  Here, depending on various conditions of the coating amount adjusting blade 72, when the angle between the coating amount adjusting blade 72 and the transport belt 28 is set to a shallow angle of about 10 ° to 30 °, the transport belt of the coating amount adjusting blade 72 is set. It has been experimentally confirmed that the coating amount adjusting blade 72 can manage the amount of scraping of the silicone oil from the transport belt 28 by changing the amount of biting into the belt 28.

  When the angle between the coating amount adjusting blade 72 and the conveying belt 28 is set to an angle deeper than 30 °, the amount of silicone oil scraped off from the conveying belt 28 by the coating amount adjusting blade 72 becomes excessive, and the blade Even if the amount of biting into the conveyor belt 28 is changed, there is almost no difference in the amount of silicone oil that the application amount adjusting blade 72 scrapes off from the conveyor belt 28. On the other hand, when the angle between the coating amount adjusting blade 72 and the transport belt 28 is set to an angle shallower than 10 °, the silicone oil is hardly scraped off from the transport belt 28 by the coating amount adjusting blade 72. For this reason, in this embodiment, the angle between the coating amount adjusting blade 72 and the conveyor belt 28 is set to about 10 ° to 30 °.

  Here, when the angle between the coating amount adjusting blade 72 and the conveying belt 28 is set to about 10 ° to 30 °, the coating amount adjusting blade 72 is applied as the amount of biting into the conveying belt 28 increases. As the scraping amount of the silicone oil from the conveyor belt 28 by the amount adjusting blade 72 decreases and the biting amount of the coating amount adjusting blade 72 into the conveyor belt 28 decreases, the silicone from the conveyor belt 28 by the coating amount adjusting blade 72 decreases. Experiments have confirmed that the amount of oil scraping increases.

  This is because as the biting amount of the coating amount adjusting blade 72 into the transport belt 28 increases, the deflection of the coating amount adjusting blade 72 increases, and the angle between the edge of the coating amount adjusting blade 72 and the transport belt 28 decreases. As a result, the amount of force with which the coating amount adjusting blade 72 scrapes the silicone oil from the conveying belt 28 is reduced, and the amount of biting of the coating amount adjusting blade 72 into the conveying belt 28 is reduced, so that the coating amount adjusting blade 72 is bent. This is presumably because the amount of the application amount adjusting blade 72 scraping the silicone oil from the conveying belt 28 increases as the angle between the edge of the applying amount adjusting blade 72 and the conveying belt 28 increases.

  In addition, a stepping motor 111 is provided that applies a rotational force to the rotating shaft 110A of the cam 110 via a gear (not shown). The stepping motor 111 is controlled by the CPU 61 as the second control unit and the third control unit, and the amount of biting of the coating amount adjusting blade 72 into the transport belt 28 is determined according to the driving amount and driving direction of the stepping motor 111. Increased or decreased.

  Here, the CPU 61 also controls the heater 54 in accordance with the detection result of the temperature sensor 58. Hereinafter, this control method will be described with reference to the flowchart of FIG.

  When the power supply of the ink jet recording apparatus 12 is turned on, the processing routine is started and the routine proceeds to step 11. In step 11, it is determined whether a print job has been received. If the determination is affirmative, the process proceeds to step 12. If the determination is negative, step 11 is repeated. In step 12, it is determined whether the total amount of preliminary discharge is less than a predetermined amount A, a predetermined amount B (> A) or more, or a predetermined amount A or more and less than a predetermined amount B. In the case, the process proceeds to step 13, the process proceeds to step 15 if it is greater than or equal to the predetermined amount B, and the process proceeds to step 17 if it is greater than or equal to the predetermined amount A and less than the predetermined amount B.

  In step 13, the stepping motor 111 is driven to reduce the amount of application of the application amount adjusting blade 72 to the conveyor belt 28 and decrease the amount of silicone oil applied to the conveyor belt 28. Then, the process proceeds to step 14. In step 14, the set temperature of the heater 54 is lowered. Then, the process proceeds to step 17.

  On the other hand, in step 15, the stepping motor 111 is driven to increase the amount of application of the application amount adjusting blade 72 to the conveyor belt 28 and increase the amount of silicone oil applied to the conveyor belt 28. Then, the process proceeds to step 16. In step 16, the set temperature of the heater 54 is raised. Then, the process proceeds to step 17.

  In step 17, the heater 54 is turned on, and the process proceeds to step 18. In step 18, it is determined whether or not the temperature detected by the temperature sensor 58 is equal to or higher than the set temperature. If the determination is negative, the process proceeds to step 17 and the heater 54 is kept on. If the determination is affirmative, step 18 is performed. 19 In step 19, the heater 54 is turned off and the routine proceeds to step 20.

  In step 20, printing is started and the process proceeds to step 21. In step 21, it is determined whether or not printing has been completed. If the determination is negative, the process proceeds to step 18 and steps 18 to 21 are repeatedly executed. If the determination is affirmative, the processing routine is ended.

  That is, in this embodiment, the amount of silicone oil applied to the conveyor belt 28 is increased when the amount of preliminary discharge discharged to the conveyor belt 28 is greater than a predetermined amount, and is decreased when it is less than the predetermined amount. As a result, the amount of silicone oil applied to the conveyor belt 28 can be kept to an amount necessary for cleaning performance, and the amount of silicone oil consumed can be reduced.

  In the present embodiment, the heating amount of the silicone oil on the blade 49 is increased when the amount of the silicone oil is larger than the predetermined amount, and is decreased when the amount of the silicone oil is smaller than the predetermined amount. Here, as the amount of ink adhering to the conveyance belt 28 increases, the ink is more easily collected on the blade 49. However, in the present embodiment, when the amount of ink adhering to the conveyance belt 28 increases, the amount of silicone oil on the blade 49 also exceeds the predetermined amount, but the heating amount of the silicone oil is increased. As a result, fluidity comparable to that in the case where the amount of silicone oil is a predetermined amount can be obtained, so that the retention of ink on the blade 49 can be suppressed. In addition, since the heating amount of the silicone oil on the blade 49 can be kept to an amount necessary for the cleaning performance, the power consumption can be reduced.

  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. Note that the rotation direction of the intermediate transfer drum 104 as a rotating body (hereinafter referred to as the drum rotation direction) is indicated by an arrow A in the figure.

  As shown in FIG. 15, the inkjet recording apparatus 100 as a droplet discharge apparatus of the present embodiment uses four colors of ink of yellow (Y), magenta (M), black (K), and cyan (C). This is a full-color printer that forms a full-color image. The ink jet recording apparatus 100 is a printer using a so-called offset printing method, and the recording head array 30 ejects ink toward an intermediate transfer drum 14 as a counter member and a carrier, and once on the intermediate transfer drum 104. Then, an ink image is formed and the ink image is transferred from the intermediate transfer drum 104 to the paper P.

  A paper feed tray 16 is provided at the bottom of the ink jet recording apparatus 100 so that it can be inserted and removed. Sheets P are stacked on the sheet feeding tray 16, and a pickup roll 18 is in contact with the uppermost sheet P. The paper P is fed one by one from the paper feed tray 16 to the downstream side in the transport direction by the pick-up roll 18, and the image forming unit is configured by the transport rolls 109, 120, 121, 123, 125 arranged in order along the transport path. Sheet 122 is fed. The transport rolls 123 and 125 are star wheels that are in contact with the surface on which the ink image of the paper P is transferred.

  In the image forming unit 122, the intermediate transfer drum 104 is disposed facing the conveyance path, the recording head array 30 is disposed above the intermediate transfer drum 104, and the maintenance unit 34 is brought close to the recording head array 30. ing.

  The recording head array 30 approaches the intermediate transfer drum 14 when ink droplets are ejected. The recording head array 30 secures a space for the maintenance unit 24 to enter the intermediate transfer drum 14 away from the intermediate transfer drum 14 during maintenance.

  The maintenance unit 34 retreats to the outside of the ejection area SE where ink droplets are ejected from the recording head array 30 during image formation. Further, the maintenance unit 34 enters the ejection area SE during non-image formation.

  In addition, a charging roll 128 as a transfer unit, a neutralizing roll 130 as a transfer unit, and a peeling claw 132 are in contact with the transfer path side of the intermediate transfer drum 104 in order from the upstream side in the transport direction. The charging roll 128 conveys the paper P while pressing it against the intermediate transfer drum 104 and applies a charge to the paper P, thereby electrostatically attracting the paper P to the intermediate transfer drum 104 and transferring the ink image onto the paper P. Further, the static elimination roll 130 removes the charge of the paper P while transporting the paper P, thereby releasing the electrostatic adsorption between the paper P and the intermediate transfer drum 104. The peeling claw 132 peels the paper P from the intermediate transfer drum 104.

  And conveyance roll 127,129,131,133,135,137,139 is arrange | positioned in the conveyance direction downstream of the peeling nail | claw 132 from the conveyance direction upstream. The transport rolls 127, 133, 135, 137, and 139 have a star wheel that is in contact with the surface on which the ink image of the paper P is transferred, and contact between the surface of the paper P on which the ink image is transferred and the roll. Is decreasing.

  A paper discharge tray 46 is disposed above the ink tank 35, and a transport roll 139 is disposed on the side of the paper discharge tray 46. That is, the paper P is discharged onto the paper discharge tray 46 by the transport roll 139.

  As shown in FIG. 16, a drum cleaning unit 148 is disposed on the downstream side in the drum rotation direction from the peeling claw 132 and on the upstream side in the drum rotation direction from the recording head array 30. The drum cleaning unit 148 abuts on the peripheral surface of the intermediate transfer drum 104, scrapes ink remaining on the intermediate transfer drum 104 without being transferred onto the paper P, and scrapes the intermediate transfer drum 104 with the blade 49. And a collection box 51 for collecting the taken 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 164 is disposed downstream of the blade 49 in the drum rotation direction and upstream of the recording head array 30 in the drum rotation direction. The oil application unit 164 includes a case 68 and an oil application roll 70 that is rotatably supported by the case 68. The oil application roll 70 is in pressure contact with the intermediate transfer drum 104 and rotates following the intermediate transfer drum 104. The oil application roll 70 is formed of a porous material such as polyethylene or urethane, impregnated with silicone oil, and applies the silicone oil to the intermediate transfer drum 104. On the other hand, the ink ejected from the recording head 32 is a water-based ink. For this reason, the ink aggregates due to the water repellent effect of the silicone oil film on the intermediate transfer drum 104. Accordingly, it is possible to suppress an increase in the force of ink adhering to the intermediate transfer drum 104, and the ink is easily peeled from the intermediate transfer drum 104 when the intermediate transfer drum 104 is cleaned by the blade 49.

  The oil application roll 70 may be a drive roll. In this case, the oil application roll 70 can be prevented from slipping with respect to the intermediate transfer drum 104.

Here, since the coating liquid needs to spread wet on the intermediate transfer drum 104, the relationship of the following formula (A) is required. However, as shown in FIG. 17, the surface tension of the coating liquid T is γ ₀ , and the critical surface tension γ _b of the intermediate transfer drum 104 is set.

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

γ ₀ <γ _i (B)
Accordingly, as in the first to third embodiments, the ink I does not spread on the film of the coating liquid T and aggregates, so that the ink on the intermediate transfer drum 104 is easily scraped off by the blade 49.

  By the way, as shown in FIG. 18A, the blade 49 is a rectangular plate material, and the entire corner (edge) 49A on one end side in the width direction is brought into contact with the outer peripheral surface of the intermediate transfer drum 104, so that The ink I and the silicone oil O adhering to the transfer drum 104 are scraped off. The blade 49 is installed so as to be inclined downward from one end side in the width direction to the other end side. For this reason, the ink I and the silicone oil O scraped from the intermediate transfer drum 104 by the edge 49A of the blade 49 flow down to the other end in the width direction of the blade 49 by their own weight, and are collected from the other end in the width direction of the blade 49. Drop into box 51.

  Here, as shown in FIG. 18B, as in the first to third embodiments, the heat ray 50 is provided on the plate surface 49B on the upstream side in the drum rotation direction of the blade 49, and the plate surface of the blade 49 is provided. The silicone oil O accumulated in 49B is heated, and the fluidity of the silicone oil O is increased. Therefore, poor cleaning of the intermediate transfer drum 104 by the blade 49 can be suppressed.

  In the first to fourth 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.

  The “droplet ejection head” in the droplet ejection apparatus of the present invention includes a wide range of means for ejecting droplets toward a recording medium or a carrier. For example, an ink jet recording head that ejects ink droplets while moving in the width direction of the paper P and shorter than the width of the paper P is included.

  In addition, the “rotating body” in the droplet discharge apparatus of the present invention includes a wide range of rotating bodies that face the droplet discharge head. For example, a conveyance drum that rotates while holding a recording medium on a peripheral surface, an intermediate transfer belt that rotates while holding a droplet, and the like are included.

  In addition, the “coating member” in the liquid droplet ejection apparatus of the present invention includes a wide range of members that apply a coating liquid having a property of repelling the liquid droplets ejected from the liquid droplet ejection head to the transport member. For example, a droplet discharge head that discharges the coating liquid toward the conveying member, a web that is impregnated with the coating liquid, contacts the conveying member, holds the coating liquid on the surface, and rotates in contact with the conveying member And a roll that is impregnated with or held on the surface of the coating liquid and that moves in a direction intersecting the transport direction by contacting the transport member.

  In addition, the “heating means” in the droplet discharge device of the present invention includes a wide range of means as long as it is a means for heating the liquid on the blade. For example, a fan that blows waste heat in the apparatus onto the blade is also included.

  Furthermore, the “cooling means” in the droplet discharge device of the present invention includes a wide variety of means as long as it is a means for cooling the contact portion between the blade and the rotating body. For example, a fan that blows cooling air toward the contact portion between the blade and the rotating body is also included.

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. FIG. 2A is an enlarged cross-sectional view of a blade and a conveyor belt provided in the ink jet recording apparatus according to the first embodiment of the present invention, and FIG. (A) is a table summarizing the relationship between kinematic viscosity at normal temperature and volatility and flash point of silicone oil, and (B) is a table summarizing the relationship between temperature and kinematic viscosity of silicone oil. . It is sectional drawing which shows the modification of the blade with which the inkjet recording device of 1st Embodiment of this invention was equipped. It is a perspective view which shows the modification of the braid | blade with which the inkjet recording device of 1st Embodiment of this invention was equipped. It is a perspective view which shows the modification of the braid | blade with which the inkjet recording device of 1st Embodiment of this invention was equipped. (A) is sectional drawing which shows the example which provided the Peltier element in the blade with which the inkjet recording device of 1st Embodiment of this invention was equipped, (B) is the inkjet recording of 1st Embodiment of this invention. It is sectional drawing which shows the example which provided the Peltier device inside the drive roll with which the apparatus was equipped. It is a side view which expands and shows a part of printing part of the inkjet recording device of 2nd Embodiment of this invention. It is a flowchart for demonstrating the control method of the heater with which the inkjet recording device of 2nd Embodiment of this invention was equipped. (A), (B) is sectional drawing which shows the blade adjustment mechanism with which the inkjet recording device of 3rd Embodiment of this invention was equipped. It is a flowchart for demonstrating the control method of the heater with which the inkjet recording device of 3rd Embodiment of this invention was equipped, and the stepping motor. It is a side view which shows the outline of the inkjet recording device of 4th 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 sectional drawing which expands and shows the surface of the intermediate transfer drum with which the inkjet recording device of 4th Embodiment of this invention was equipped. 4A and 4B are enlarged views showing a blade and an intermediate transfer drum provided in an ink jet recording apparatus according to a fourth embodiment of the present invention, and FIG.

Explanation of symbols

12 Inkjet recording device (droplet ejection device)
28 Conveyor belt (rotating body)
32 Inkjet recording head (droplet ejection head)
49 Blade 49A Edge 50 Hot wire (heating means, heating element)
52 Peltier element (cooling means)
54 Heater (heating means)
56 Heat insulation plate (heat insulation member)
58 Temperature sensor (temperature detection means)
60 CPU (first control means)
61 CPU (first control means, second control means)
70 Oil application roll (application member)
100 Inkjet recording device (droplet ejection device)
104 Intermediate transfer drum (rotating body)

Claims (9)

A droplet discharge head for discharging liquid in droplets;
A rotating body facing the droplet discharge head;
A blade that contacts the rotating body and cleans the opposing member;
A coating member that coats the rotating body with a coating liquid having a property of repelling liquid ejected from the droplet ejection head;
Heating means for heating the coating solution on the blade;
A droplet discharge apparatus comprising:   2. The droplet discharge device according to claim 1, wherein the heating unit is disposed away from a contact portion of the blade with the rotating body on the side opposite to the rotating body.   The droplet discharge device according to claim 1, further comprising a cooling unit that cools a contact portion of the blade with the rotating body.   4. The droplet discharge device according to claim 1, wherein the heating unit is a heating element provided on the blade. 5.   The droplet discharge device according to claim 4, wherein the heating element is provided on a plate surface of the blade facing the upstream side in the rotation direction of the rotating body. The heating means is a heating element that is disposed facing the plate surface facing the upstream side in the rotation direction of the rotating body of the blade, and generates heat toward the plate surface,
The liquid droplet ejection apparatus according to claim 1, wherein a heat insulating member is provided between the heat generating body and the rotating body. Temperature detecting means for detecting the temperature of the surface of the blade;
First control means for controlling the heating means according to the temperature detected by the temperature detection means;
The liquid droplet ejection apparatus according to claim 1, wherein the liquid droplet ejection apparatus includes:   8. The apparatus according to claim 1, further comprising a second control unit configured to control the heating unit according to an amount of liquid ejected by the droplet ejection head during preliminary ejection. The liquid droplet ejection apparatus described.   9. The apparatus according to claim 1, further comprising a third control unit configured to control the heating unit according to an amount of the coating liquid applied to the rotating body by the coating member. Droplet discharge device.

Images