JP2008179094A - Liquid droplet discharge device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent ink in a nozzle from contacting air by neither increasing the number of components nor enlarging the device. <P>SOLUTION: An inkjet recording head 20 is lowered to allow a nozzle face to be fitted to a conveyance belt 30 so as to bring the conveyance belt 30 into intimate contact with the nozzle face. Consequently, the nozzle can be closed by interposing no air between the nozzle face and the conveyance belt 30 so that the ink in the nozzle is hardly dried and dust does not stick to the nozzle face. As the conveyance belt 30 of a conveyance device 16 for conveying recording paper P is brought into intimate contact with the nozzle face to close the nozzle, it is not necessary to additionally provide a member to be into intimate contact with the nozzle face. Therefore, the number of components is not increased and a space for shunting the member is not necessary so that the inkjet recorder 10 is not enlarged. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a droplet discharge device that discharges droplets from a nozzle.

  In an ink jet recording apparatus (droplet discharge apparatus) that discharges ink droplets from a plurality of nozzles formed on a nozzle plate and attaches ink droplets to a recording medium to perform printing (image recording), the printing pause state continues for a long time. If the ink dries and the nozzles are clogged, or dust adheres to the nozzle plate, dot dropout may occur during printing, and the print quality may deteriorate or printing may become impossible.

  Therefore, when printing (recording) is suspended for a certain time or longer, a concave cap is brought into contact with the nozzle surface of the nozzle plate to prevent the ink in the nozzle from drying and the dust from adhering to the nozzle plate. Yes.

  However, when the cap is brought into contact with the nozzle surface, a space formed by the nozzle surface and the cap is formed around the nozzle, so that the ink in the nozzle increases in viscosity when the ink in the nozzle touches the air in this space. As a result, there is a problem that the ink is dried and the nozzle is clogged with the passage of time.

  Therefore, as a means for improving this problem, a method has been proposed in which a sheet-like cap is brought into close contact with the nozzle surface of the nozzle plate (see Patent Document 1). By fixing the sheet-like cap to the nozzle surface as in Patent Document 1, it is possible to prevent the ink in the nozzle from coming into contact with the air and drying the ink in the nozzle.

However, this sheet-like cap needs to be moved below the nozzle only when necessary, and must be retracted from below the nozzle when it is not necessary. Necessary. This increases the number of parts and increases the size of the ink jet recording apparatus, leading to an increase in cost.
JP-A-9-123470

  In view of the above problems, an object of the present invention is to prevent ink in a nozzle from coming into contact with air without causing an increase in the number of parts or an increase in size.

  The present invention described in claim 1 includes a droplet discharge head having a nozzle surface on which nozzles for discharging droplets are formed, and a droplet discharge region in which droplets are discharged from the droplet discharge head, Transporting the recording medium to the droplet discharge area, or transferring a droplet discharged to the droplet discharge area to the recording medium; and moving the droplet discharge head or the transport member, Contact means for bringing the conveying member into close contact with the nozzle surface.

  In the first aspect of the invention, the droplet discharge head or the transport member is moved by the contact means, and the transport member is brought into close contact with the nozzle surface of the droplet discharge head.

  As a result, the nozzle can be closed without interposing air between the nozzle surface and the conveying member, so that the liquid in the nozzle is difficult to dry and dust does not adhere to the nozzle surface.

  In addition, the recording medium is conveyed to the droplet discharge area, and an image is recorded on the recording medium with the droplet discharged from the droplet discharge head, or the liquid discharged to the droplet discharge area is transferred to the recording medium. Since the conveying member for transferring the image onto the recording medium and closely contacting the nozzle surface closes the nozzle, it is not necessary to separately provide a member closely contacting the nozzle surface (closing the nozzle).

  Therefore, compared to a case where a member for closely contacting the nozzle surface is provided, the number of parts does not increase in this configuration, and a space for retracting the member is not required. Becomes smaller.

  According to a second aspect of the present invention, the conveying member is a conveying belt wound around a roller, and the contact means has a nozzle contact surface of the conveying belt, to which the nozzle surface of the droplet discharge head is in close contact. The droplet discharge head or the conveying member is moved until the belt falls below the other belt surface.

  According to the second aspect of the present invention, the droplet discharge head or the transport member is moved by the close contact means, and the nozzle contact surface of the transport belt wound around the roller is in contact with the nozzle surface of the droplet discharge head. It is lowered from the belt surface. As a result, the nozzle surface bites into the transport member, and the nozzle surface is sealed by the transport member, so that the degree of adhesion between the nozzle surface and the transport member is increased.

  According to a third aspect of the present invention, an elastic member is provided on the side opposite to the droplet discharge area of the transport member so as to hit the transport member when the droplet discharge head or the transport member is moved. It is characterized by being.

  In the invention according to claim 3, by providing an elastic member on the side opposite to the droplet discharge region of the transport member, for example, when the droplet discharge head is lowered and the transport member is brought into close contact with the nozzle surface, the elastic member Pushes the conveying member with an elastic force from the opposite side, so that variations in the nozzle surface are absorbed. Therefore, even if there are a plurality of droplet discharge heads and the positions of the nozzle surfaces of the respective droplet discharge heads vary, there is no gap between the nozzle surface and the conveying member, and the adhesion is improved.

  The present invention according to claim 4 is characterized in that a cleaning member for cleaning the surface of the conveying member is provided.

  In the invention according to claim 4, the surface of the conveying member is cleaned by the cleaning member provided on the surface to which the nozzle surface of the conveying member is in close contact. Thereby, dust and liquid adhering when the conveying member is brought into close contact with the nozzle surface is removed from the conveying member. Therefore, the next time the conveying member is brought into close contact with the nozzle surface, dust or liquid does not adhere to the nozzle surface from the conveying member.

  The present invention according to claim 5 is characterized in that a seal liquid is applied to a surface of the conveying member to which the nozzle surface is in close contact.

  In the fifth aspect of the present invention, the sealing liquid is applied to the surface to which the nozzle surface of the conveying member is in close contact. Thus, when the nozzle surface and the transport member are brought into close contact with each other, the seal liquid seals between the nozzle surface and the transport member. Therefore, even if a minute gap is left when the nozzle surface and the conveying member are brought into close contact with each other, the sealing is performed by the sealing liquid, so that the adhesion between the nozzle surface and the conveying member is improved.

  The present invention according to claim 6 is characterized in that the seal liquid has a property of spreading wet with respect to the transport member.

  In the sixth aspect of the invention, the sealing liquid can be uniformly interposed between the nozzle surface and the conveying member by applying the sealing liquid having the property of spreading on the conveying member to the conveying member.

  The present invention according to claim 7 is characterized in that the sealing liquid has a property of repelling the liquid discharged from the nozzle.

  According to the seventh aspect of the present invention, the liquid on the nozzle surface adhered when the nozzle surface and the transport member are brought into close contact with each other by applying a sealing liquid having a property of repelling the liquid discharged from the nozzle to the transport member. Since dust is repelled by the sealing liquid, it is easily cleaned by the cleaning member.

  The present invention according to claim 8 is characterized in that the sealing liquid is incompatible with the liquid discharged from the nozzle.

  In the invention according to claim 8, even if the sealing liquid adheres to the nozzle surface by applying a sealing liquid that is incompatible with the liquid discharged from the nozzle to the conveying member, the liquid and the sealing liquid Will not mix. As a result, color mixing caused by mixing the liquid and the seal liquid, deterioration in image quality, and the like are unlikely to occur.

  The present invention according to claim 9 is characterized in that the seal liquid is a liquid discharged from the droplet discharge head.

  In the ninth aspect of the invention, when the nozzle surface and the transport member are brought into close contact with each other, a liquid is discharged from the droplet discharge head, and the liquid is sealed between the nozzle surface and the transport member. This eliminates the need for a device for applying the sealing liquid to the conveying member, so that the number of parts does not increase and the droplet discharge device does not increase in size.

  Since the present invention has the above-described configuration, the ink in the nozzles can be prevented from touching the air without increasing the number of parts or increasing the size.

  Hereinafter, an inkjet recording apparatus 10 as a liquid droplet ejection apparatus according to a first embodiment of the present invention will be described with reference to the drawings.

  1 and 2 show a schematic configuration of the ink jet recording apparatus 10. The inkjet recording apparatus 10 includes a paper feed cassette 12 in which the recording paper P is accommodated, an image recording unit 14 that records an image on the recording paper P supplied from the paper feed cassette 12, and a recording paper P to the image recording unit 14. And a paper discharge tray 18 for storing the recording paper P on which an image is recorded by the image recording unit 14.

  The image recording unit 14 includes an ink jet recording head 20, and the ink jet recording head 20 is approximately equal to or greater than the maximum width of the recording paper P on which image recording with the ink jet recording apparatus 10 is assumed. It has a recordable area. That is, the ink jet recording head 20 is a so-called full width array (FWA) capable of single pass printing.

  Further, the inkjet recording head 20 is arranged in parallel in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side with respect to the conveyance direction of the recording paper P. The ink droplets are ejected from the nozzles by a known means such as a method or a piezoelectric method. In addition to this, an ink jet recording head (not shown) for discharging a transparent processing liquid for ink fixing may be provided in parallel.

  Further, as the ink, various inks such as water-based ink, oil-based ink, solvent-based ink, and the like can be used, and an ink tank that supplies ink to each of the ink jet recording heads 20Y, 20M, 20C, and 20K is used in the ink jet recording apparatus 10. 21Y, 21M, 21C, and 21K are provided. In the following, when it is necessary to distinguish YMCK, any of Y, M, C, and K is added after the sign, and when it is not necessary to distinguish YMCK, Y, M, C, and K are omitted. To do.

  Further, the inkjet recording head 20 is provided with a maintenance unit 22. The maintenance unit 22 is configured to be movable between a retracted position during printing (see FIG. 1, the back side of the inkjet recording head 20 in the drawing) and a position for maintaining the inkjet recording head 20 (see FIG. 2). Yes.

  The maintenance unit 22 has a cleaning member (wiper blade) and the like. When the inkjet recording head 20 is maintained, the inkjet recording head 20 is raised by a predetermined height, and the maintenance unit 22 is moved from the back to the front in the drawing. As a result, the maintenance units 22 are arranged to face the nozzle surface of the inkjet recording head 20. A mechanism for raising and lowering the inkjet recording head 20 will be described later.

  On the other hand, a paper feed cassette 12 in which recording paper P is stored is disposed below the ink jet recording apparatus 10. The recording paper P in the paper cassette 12 is picked up one by one by a pickup roller 24 and is transported through a transport path 23 by a pair of transport rollers 25, and a transport belt 30 and a drive roller that stretches the transport belt 30. 26 and the driven rollers 27, 28, and 29. Details of the transfer device 16 will be described later.

  Further, a reversing unit 36 is provided between the paper feed cassette 12 and the transport device 16, and when performing double-sided printing, the transport roller pair 38 is provided with a plurality of transport roller pairs 38 whose surface side immediately after printing is a star wheel. The recording paper P is transported through the transport path 37 provided with the pair 38 and is sent to the transport device 16 again. Further, a plurality of transport roller pairs 38 having a star wheel on the surface immediately after printing of the recording paper P are provided at appropriate positions on the transport path 39 from the transport device 16 to the paper discharge tray 18.

  In addition, although not shown, the inkjet recording apparatus 10 determines the ink droplet ejection timing and the nozzle to be used in accordance with the image signal, and applies control signals to the inkjet recording head 20 for applying a drive signal to the nozzle. System control means for controlling the operation of the entire recording apparatus 10 is provided.

  Next, the ink jet recording head 20 and the transport device 16 in the ink jet recording apparatus 10 having the above configuration will be described.

  As shown in FIG. 4, the inkjet recording head 20 is held in a rectangular box-shaped base 40, and the nozzle surface of each inkjet recording head 20 is exposed from the lower surface of the base 40.

  Two long cylindrical guide members 42 are integrally provided on one side wall in the width direction of the recording paper P of the base 40. A guide hole 41 passes through the guide member 42 in the vertical direction, and a shaft 44 is inserted into the guide hole 41 in a slidable state.

  A long cylindrical guide member 46 is integrally provided on the other side wall of the base 40. A screw groove 45 is formed in the guide member 46 in the vertical direction, and a ball screw 48 whose upper and lower ends are rotatably supported by a support plate (not shown) is screwed into the screw groove 45.

  A gear 54 is connected to the lower end of the ball screw 48. A gear 58 provided on a rotation shaft 56A of the motor 56 is engaged with the gear 54, and when the gear 58 is rotated by driving the motor 56, the ball screw 48 is rotated integrally with the gear 54. .

  With such a configuration, when the ball screw 48 is rotated by driving the motor 56, the guide member 46 to which the ball screw 48 is screwed moves in the vertical direction, and the base 40 moves up and down while being guided by the shaft 44. . Then, the inkjet recording head 20 is moved up and down by moving the base 40 up and down.

  On the other hand, as shown in FIG. 3, the conveyance device 16 provided below the inkjet recording head 20 has a conveyance belt 30 facing the nozzle surface of the inkjet recording head 20. The conveyor belt 30 is stretched between a driving roller 26 disposed on the downstream side in the sheet conveying direction and driven rollers 27, 28, and 29 disposed on the upstream side in the sheet conveying direction. It is configured to circulate (rotate) around.

  The driving roller 26 and the driven roller 27 are disposed substantially horizontally, and the driven roller 28 and the driven roller 29 are disposed substantially horizontally below the driving roller 26 and the driven roller 27. The transport belt 30 is a region stretched between the driving roller 26 and the driven roller 27, and forms a flat portion facing the nozzle surface of the ink jet recording head 20, and the region of the flat portion facing the nozzle surface. However, this is an ejection region SE where ink droplets are ejected from the inkjet recording head 20.

  Then, the recording paper P sent out from the paper feed cassette 12 (see FIG. 1) and transported through the transport path 23 is held by the transport belt 30 to reach the discharge area SE and face the nozzle surface of the ink jet recording head 20. In this state, ink droplets corresponding to the image information are attached from the nozzles of the inkjet recording head 20.

  In addition, a paper pressing roller 32 that is driven from the front side of the conveyance belt 30 is provided on the driven roller 27 from the front side. The sheet pressing roller 32 also serves as a charging roller. When the conveying belt 30 is charged (charged) by the sheet pressing roller 32, the recording sheet P is electrostatically attracted to the conveying belt 30 and conveyed. It has become so.

  For example, PET (polyester), PI (polyimide), PA (polyamide), PC, and the like, which are made of a flexible polymer material that can retain electric charges on the surface by being charged. (Polycarbonate) or the like or rubber material. For example, it is formed of members such as CR (chloroprene rubber), NBR (nitrile rubber), HNBR (hydrogenated nitrile rubber), urethane rubber, etc., and has a sheet-like confidentiality (micropores like a porous body) Any member that is not available may be used.

  Further, a separation claw 34 for separating the recording paper P from the conveyance belt 30 is disposed in the vicinity of the driving roller 26 of the conveyance belt 30 so as to be able to approach and separate. As a result, the recording paper P printed by the ink jet recording head 20 is peeled from the transport belt 30 by the curvature of the transport belt 30 and the peeling claw 34 and sent to the transport path 39 on the downstream side of the transport device 16. Yes.

  Further, a belt cleaning unit 60 is disposed near the downstream side of the peeling claw 34 of the driving roller 26. The belt cleaning unit 60 has a blade 62 that abuts on a portion of the transport belt 30 that is wound around the driving roller 26 and scrapes off ink or the like adhering to the transport belt 30. The blade 62 is fixed to a support piece 64 </ b> A protruding from the inner wall of the collection box 64, and ink and the like scraped from the conveyance belt 30 by the blade 62 are collected in the collection box 64. . In addition, an absorber 66 is spread on the bottom of the collection box 64, and the liquid dropped from the blade 62 is absorbed by the absorber 66.

  Next, the printing operation in the inkjet recording apparatus 10 configured as described above will be described based on the flowcharts shown in FIGS.

  As shown in FIG. 5A, the ink jet recording head 20 has a position where the nozzle contact surface of the conveying belt 30 to which the nozzle surface is in contact is lowered from the other belt surfaces before the printing operation is started. Waiting (in a state where the nozzle surface bites into the conveyor belt 30).

  Then, as shown in FIG. 7, when a print job is input and a printing operation is started, in step 100, the motor 56 (see FIG. 4) is driven, and as shown in FIG. The recording head 20 is raised to the nozzle cleaning position. Thereby, a space in which the maintenance unit 22 can enter is formed between the nozzle surface of the inkjet recording head 20 and the transport belt 30.

  In the next step 102, as shown in FIG. 5C, the maintenance unit 22 moves, and the nozzle surface of the inkjet recording head 20 is wiped by the cleaning member of the maintenance unit 22, and the ink adhered to the nozzle surface. Remove dust and dirt.

  When the cleaning of the nozzle surface is completed, the maintenance unit 22 retracts from between the nozzle surface of the inkjet recording head 20 and the conveying belt 30 in step 104.

  Then, in the next step 106, the motor 56 is driven, and the ink jet recording head 20 is lowered to the printing position as shown in FIG. At this time, a predetermined gap is formed between the nozzle surface of the inkjet recording head 20 and the conveyance belt 30.

  In step 108, as shown in FIG. 6A, a dummy jet is discharged from the nozzles of the inkjet recording head 20 toward the conveyance belt 30. As a result, the ink in the nozzles is ejected onto the transport belt 30.

  When the discharge of the dummy jet is completed, in step 110, the driving roller 26 is driven to rotate the conveyor belt 30, and the blade of the belt cleaning unit 60 that is in contact with the conveyor belt 30 as shown in FIG. At 62, the ink by the dummy jet adhering to the conveyance belt 30 is removed.

  Next, in step 112, one sheet of recording paper P is taken out from the paper feed cassette 12 by the pickup roller 24 (see FIG. 1) and supplied onto the conveying belt 30. The recording paper P is sucked and held on the transport surface of the transport belt 30 and transported to the discharge area SE (see FIG. 3). In step 114, as shown in FIG. 6C, ink is ejected from the inkjet recording head 20, and printing is performed on the recording paper P.

  When printing on the recording paper P is completed and there is no information about the printing operation start, the ink jet recording head 20 is lowered by driving the motor 56 in step 116 as shown in FIG. At this time, after the nozzle surface comes into contact with the conveyance belt 30, the inkjet recording head 20 is further lowered to cause the nozzle surface to bite into the conveyance belt 30, thereby bringing the conveyance belt 30 into close contact with the nozzle surface.

  As a result, the nozzle can be closed without interposing air between the nozzle surface and the conveying belt 30, so that the ink in the nozzle is difficult to dry and dust does not adhere to the nozzle surface.

  Further, since the conveying belt 30 of the conveying device 16 that conveys the recording paper P is brought into close contact with the nozzle surface to close the nozzle, it is not necessary to separately provide a member that closely contacts the nozzle surface (closes the nozzle). Therefore, the number of parts does not increase and a space for retracting the member is not required, so that the inkjet recording apparatus 10 is not increased in size.

  Further, since the inkjet recording head 20 is lowered and the conveying belt 30 is brought into close contact with the nozzle surface by using a mechanism for raising and lowering the inkjet recording head 20 during maintenance, a mechanism for bringing the conveying belt 30 into close contact with the nozzle surface is provided. There is no need to provide it separately.

  Further, when the transport belt 30 is brought into close contact with the nozzle surface of the inkjet recording head 20, the nozzle surface is bitten into the transport belt 30, so that the nozzle surface is firmly sealed by the transport belt 30, and the nozzle surface and the transport belt 30. There are no gaps between them.

  In this embodiment, the inkjet recording head 20 is lowered so that the conveyance belt 30 is brought into close contact with the nozzle surface. However, an elevating mechanism for raising the conveyance device 16 is provided, and the inkjet recording head 20 is not lowered. Alternatively, the conveying device 16 may be raised to bring the conveying belt 30 into close contact with the nozzle surface.

  Next, an ink jet recording apparatus according to a second embodiment of the present invention will be described. In addition, the description about the part similar to 1st Embodiment is omitted.

  As shown in FIG. 8A, a support plate 68 having an area substantially the same as or larger than the nozzle surface of the inkjet recording head 20 is parallel to the conveyance surface of the conveyance belt 30 on the back surface side of the conveyance belt 30. It is provided to become. The support plate 68 is attached to the frame of the ink jet recording apparatus, and is provided in a state where a distance slightly larger than the thickness of a pressing member 70 described later is provided between the support plate 68 and the conveyance belt 30.

  An elastic pressing member 70 is disposed on the surface of the support plate 68 facing the conveying belt 30. The pressing member 70 is made of, for example, sponge or rubber, and a slight gap is formed between the surface of the pressing member 70 (the surface facing the conveying belt 30) and the back surface of the conveying belt 30. Yes.

  When the pressing member 70 is provided on the back surface (opposite side of the ejection region SE) of the transport belt 30 as described above, when the ink jet recording head 20 is lowered and the nozzle surface is brought into close contact with the transport belt 30, FIG. As shown in (B), since the pressing member 70 presses the conveying belt 30 with an elastic force from the side opposite to the side where the inkjet recording head 20 is provided, the variation in the nozzle surface is absorbed. Therefore, when a plurality of inkjet recording heads 20 are provided, no gap is formed between the nozzle surface and the conveyor belt 30 even if the positions of the nozzle surfaces vary.

  Next, an ink jet recording apparatus according to a third embodiment of the present invention will be described. In addition, the description about the part similar to 1st Embodiment is omitted.

  As shown in FIG. 9, an oil application unit 72 that applies silicone oil to the transport belt 30 is disposed below the driven roller 29. In addition, since silicone oil is apply | coated to the conveyance belt 30, the water-based ink is used as an ink here.

  The oil application unit 72 includes a rectangular box-shaped case 74, and a supply shaft 78 and a take-up supply shaft 78 are rotatably supported in the case 74 along the conveyance direction of the conveyance belt 30. Yes.

  Also, in the case 74, a pressure contact roll 80 is rotatably supported between the supply shaft 78 and the take-up supply shaft 78 so as to contact the conveyance belt 30 wound around the driven roller 29. The pinch rolls 82 and 84 are rotatably supported between the supply shaft 78 and the pressure contact roll 80 and between the take-up supply shaft 78 and the pressure contact roll 80, respectively.

  One end of a belt-like web 76 impregnated with silicone oil is wound around the supply shaft 78. As the material constituting the web 76, a nonwoven fabric made of polyester, polyamide or the like is suitable, but other materials can be used as long as they can contain a predetermined amount of sealing liquid and can be wound up. May be.

  The web 76 is brought into contact with the conveyance belt 30 wound around the driven roller 29 by a pressure contact roll 80, and the other end is wound around a winding supply shaft 78. Further, the web 76 is given a predetermined tension by the pinch rolls 82 and 84 between the supply shaft 78 and the pressure contact roll 80 and between the pressure contact roll 80 and the supply shaft 78, respectively.

  The take-up supply shaft 78 is driven by a motor 86. When the take-up supply shaft 78 is rotated by the drive of the motor 86, the web 76 is fed out from the supply shaft 78 and taken up by a minute amount. It is conveyed to the supply shaft 78 side.

  Thus, silicone oil is always applied to the conveyor belt 30 at the nip portion between the pressure roller 80 and the driven roller 29, and a silicone oil film is formed on the conveyor belt 30.

  In this way, when the nozzle surface and the transport belt 30 are brought into close contact with each other by applying silicone oil to the transport belt 30, the silicone oil is interposed between the nozzle surface and the transport belt 30 and seals. As a result, even when a minute gap is left when the nozzle surface and the transport belt 30 are brought into close contact with each other, the nozzle surface and the transport belt 30 are improved in adhesion because they are sealed with silicone oil.

  Here, silicone oil is used as the liquid (hereinafter referred to as “seal liquid”) applied to the conveyor belt 30 by the web 76. However, in addition to silicone oil, fluorine oil, mineral oil, vegetable oil, etc. You may apply what has water nature, and what mixed these.

  In this way, by applying a water-repellent sealing liquid on the conveyor belt 30, the conveyor belt 30 can be ejected by unnecessary ink when ink mist or paper jam occurs, or by a dummy jet or the like ejected onto the conveyor belt 30. When ink adheres to the ink, the ink aggregates due to the water repellent effect of the silicone oil film on the conveyor belt 30. Accordingly, the force of ink adhering to the conveyance belt 30 can be suppressed, and the ink is easily peeled from the conveyance belt 30 when the conveyance belt 30 is cleaned by the blade 62.

In addition, a seal liquid having a property of spreading on the conveyor belt 30 is used. In order to have the property that the sealing liquid wets and spreads on the conveying belt 30, when the surface tension of the sealing liquid is γ ₀ and the critical surface tension γ _b of the conveying belt 30, a relationship of γ ₀ <γ _b is necessary. It is. Here, the critical surface tension means that when cos θ is corrected to 1 in relation to the surface tension of various liquids and the contact angle θ of the solid surface (that is, when the contact angle of the liquid with respect to the solid surface becomes 0 °). ) 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.

  As a result, when the sealing liquid is applied to the conveyance belt 30, the sealing liquid wets and spreads on the conveyance belt 30, and the application failure of the sealing liquid to the conveyance belt 30 does not occur. Therefore, when the nozzle surface is pressed against the conveyance belt 30, the sealing liquid is uniformly interposed between the nozzle surface and the conveyance belt 30.

  Furthermore, if a liquid that is incompatible with the ink ejected from the inkjet recording head 20 is used as the sealing liquid, even if the sealing liquid adheres to the nozzle surface, the sealing liquid mixes with the ink. There is no. As a result, color mixing caused by mixing the sealing liquid with ink, deterioration in print image quality, and the like are unlikely to occur.

  Even if the sealing liquid is not incompatible, the recording paper P can be obtained by performing a dummy jet or performing a maintenance operation such as capping the nozzle surface to suck ink mixed with the sealing liquid in the nozzle. It is possible to prevent the above-mentioned color mixture and the deterioration of the print image quality. However, there is a problem that the amount of ink consumption correspondingly increases.

  If the sealing liquid is a non-volatile liquid, the adhesion between the nozzle surface and the conveyor belt 30 can be maintained for a long time. Furthermore, since it does not evaporate even if it is applied to the conveyor belt 30, it is not necessary to frequently apply a sealing liquid to the conveyor belt 30. Therefore, the consumption amount of the sealing liquid can be suppressed as compared with the case where the volatile sealing liquid is applied to the conveying belt 30.

  Further, as the sealing liquid, it is possible to use an ink containing no pigment or dye, or a liquid containing a surfactant.

  In order to perform the printing operation, when the ink jet recording head 20 is raised and the adhesion between the nozzle surface and the conveyance belt 30 is released, the silicone oil applied to the conveyance belt 30 adheres to the nozzle surface. The silicone oil adhering to the nozzle surface is removed from the nozzle surface when the cleaning member of the maintenance unit 22 cleans the nozzle surface of the inkjet recording head 20.

  The oil application unit 72 can be pulled to the near side of the drawing with respect to the ink jet recording apparatus main body. Thus, when most of the web 76 wound around the supply shaft 78 is wound up on the take-up supply shaft 78, the oil application unit 72 is removed from the ink jet recording apparatus main body and a new oil application unit 72 is attached. Is possible.

  Furthermore, in this embodiment, the web 76 is always brought into contact with the conveyance belt 30 wound around the driven roller 29 by the pressure roll 80, but an elevating device is provided in the oil application unit 72, and the pressure roll 80 is conveyed to the conveyance belt. The liquid seal may be applied to the transport belt 30 only when the nozzle surface can be brought into contact with and separated from the transport belt 30 and the nozzle surface is brought into close contact with the transport belt 30.

  Next, an ink jet recording apparatus according to a fourth embodiment of the present invention will be described. In addition, the description about the part similar to 1st Embodiment is omitted.

  As shown in FIG. 10A, the ink jet recording head 20 is lowered, and ink is ejected from the ink jet recording head 20 onto the transport belt 30 immediately before the nozzle surface is brought into close contact with the transport belt 30.

  Then, when the nozzle surface is brought into close contact with the conveyance belt 30 wet with ink, the ink is sealed between the nozzle surface and the conveyance belt 30 as shown in FIG. 10B. As a result, even if a minute gap is left when the nozzle surface and the transport belt 30 are brought into close contact with each other, the ink is sealed with ink, so that the adhesion between the nozzle surface and the transport belt 30 is improved.

  Next, an ink jet recording apparatus according to a fifth embodiment of the present invention will be described. In addition, the description about the part similar to 1st Embodiment is omitted.

  As shown in FIG. 11, each color ink is ejected onto the conveyor belt 30 from each inkjet recording head 20 </ b> Y, 20 </ b> M, 20 </ b> C, 20 </ b> K.

  Yellow ink is ejected from the yellow inkjet recording head 20 </ b> Y, and yellow printing is performed on the conveyance belt 30. Then, the magenta ink is ejected from the inkjet recording head 20M so as to overlap the yellow printing, and the cyan ink is superimposed from the inkjet recording head 20C on the yellow and magenta printing on the conveyance belt 30. Discharged.

  Further, black ink is ejected from the inkjet recording head 20K so as to overlap the yellow, magenta, and cyan prints on the transport belt 30, and the four colors of ink are superimposed on the transport belt 30 for printing. Is done.

  On the other hand, the driven roller 29 constituting the conveying device 16 is disposed below and substantially in the center of the driven roller 27 and the driving roller 26, and a transfer roller 88 is disposed facing the driven roller 29. ing.

  As shown in FIG. 12, the shaft 88A of the transfer roller 88 is inserted into a long hole 90 formed in the frame 11 of the ink jet recording apparatus (see FIG. 1). Thereby, the transfer roller 88 is movable in the vertical direction along the long hole 90.

  The shaft 88A is pivotally supported by a bearing 92 disposed on the outer side of the frame 11 (on the side opposite to the side on which the transfer roller 88 is disposed). The bearing 92 is substantially formed on the plate 94. It is supported by a U-shaped receiving portion 94A.

  The plate member 94 is attached so as to be slidable in the vertical direction with respect to the frame 11 along a guide rail (not shown). A substantially elliptical eccentric cam 96 is in contact with the bottom of the plate 94. A gear 98 is attached to the shaft 96A of the eccentric cam 96, and a drive gear 154 attached to the shaft 152A of the motor 152 is engaged with the gear 98.

  As a result, when the motor 152 is driven, the transfer roller 88 rises and comes into contact with the portion of the conveyor belt 30 that is wound around the driven roller 29.

  As shown in FIG. 11, a paper transport roller pair 156 is provided on the upstream side of the transfer roller 88 in the transport direction of the recording paper P, and a paper guide 158 is provided between the paper transport roller pair 156 and the transfer roller 88. Is provided.

  Further, on the downstream side of the transfer roller 88 in the conveyance direction of the recording paper P, a paper discharge roller pair 160 in which the surface immediately after printing of the recording paper P (the side facing the driven roller 29) is a star wheel is provided. A paper guide 162 is provided between the transfer roller 88 and the paper discharge roller pair 160.

  As a result, the recording paper P sent out from the paper feed cassette 12 (see FIG. 1) is transported through the paper guide 158 by the paper transport roller pair 156 and sent between the transfer roller 88 and the driven roller 29. Then, the print on the conveyor belt 30 is transferred to the recording paper P sent between the transfer roller 88 and the driven roller 29, and discharged to the paper discharge tray 18 (see FIG. 1) by the paper discharge roller pair 160. .

  The oil application unit 72 is disposed in the vicinity of the drive roller 26 and applies silicone oil to the conveyance belt 30 immediately before the conveyance belt 30 is brought into close contact with the nozzle surface.

  Next, the printing operation in the ink jet recording apparatus having the above configuration will be described with reference to the flowcharts shown in FIGS.

  As shown by the solid line in FIG. 11, the inkjet recording head 20 stands by at a position where the nozzle surface bites into the conveyance belt 30 before the printing operation is started. Then, as shown in FIG. 13, when a print job is input and a printing operation is started, in step 130, the inkjet recording head 20 is raised to the nozzle cleaning position. Thereby, a space in which the maintenance unit 22 can enter is formed between the nozzle surface of the inkjet recording head 20 and the transport belt 30.

  In the next step 132, the maintenance unit 22 moves, and the nozzle surface of the inkjet recording head 20 is wiped by the cleaning member of the maintenance unit 22 to remove ink and dust adhering to the nozzle surface.

  When the cleaning of the nozzle surface is completed, the maintenance unit 22 retracts from between the nozzle surface of the inkjet recording head 20 and the conveying belt 30 in step 134.

  In the next step 136, the inkjet recording head 20 is lowered to the printing position. At this time, a predetermined gap is formed between the nozzle surface of the inkjet recording head 20 and the conveyance belt 30.

  In step 138, a dummy jet is ejected from the nozzles of the inkjet recording head 20 toward the transport belt 30. As a result, the dried ink or the like in the nozzles is ejected onto the transport belt 30.

  When the discharge of the dummy jet is completed, in step 140, the driving roller 26 is driven to rotate the conveyance belt 30, and the blade 62 of the belt cleaning unit 60 that is in contact with the conveyance belt 30 adheres to the conveyance belt 30. Remove the ink by the dummy jet.

  Next, in step 142, the motor 152 (see FIG. 12) is driven, and the transfer roller 88 rises and comes into contact with the portion of the conveyor belt 30 that is wound around the driven roller 29. In the next step 144, ink is ejected from each inkjet recording head 20 onto the conveyance belt 30, and printing is performed on the conveyance belt 30.

  Next, in step 146, one sheet of recording paper P is taken out from the paper feed cassette 12 by the pickup roller 24 (see FIG. 1), supplied between the transfer roller 88 and the driven roller 29, and printed on the conveying belt 30. Is transferred to the recording paper P.

  In the next step 148, the transfer roller 88 is lowered by the drive of the motor 152 and separated from the transport belt 30.

  If there is no information about the start of the next printing operation, in step 150, silicone oil is applied to the conveyor belt 30 by the oil application unit 72. In step 152, as shown by the solid line in FIG. The head 20 is lowered to cause the nozzle surface to bite into the transport belt 30, and the transport belt 30 is brought into close contact with the nozzle surface.

  As a result, the nozzle can be closed without interposing air between the nozzle surface and the conveying belt 30, so that the ink in the nozzle is difficult to dry and dust does not adhere to the nozzle surface.

1 is a schematic view of an ink jet recording apparatus of the present invention. 1 is a schematic view of an ink jet recording apparatus of the present invention. FIG. 2 is a side view illustrating an outline of an ink jet recording head and a conveying member mounted on the ink jet recording apparatus according to the first embodiment of the present invention. 1 is a perspective view showing an ink jet recording head mounted on an ink jet recording apparatus according to a first embodiment of the present invention. FIG. 3 is a side view showing a positional relationship between an ink jet recording head mounted on the ink jet recording apparatus according to the first embodiment of the present invention and a conveying member. FIG. 3 is a side view showing a positional relationship between an ink jet recording head mounted on the ink jet recording apparatus according to the first embodiment of the present invention and a conveying member. It is a flowchart which shows the printing operation | movement of the inkjet recording device of 1st Embodiment of this invention. It is a side view which shows the outline of the inkjet recording head and conveyance member mounted in the inkjet recording device of 2nd Embodiment of this invention. It is a side view which shows the outline of the inkjet recording head and conveyance member mounted in the inkjet recording device of 3rd Embodiment of this invention. It is a side view which shows the outline of the inkjet recording head mounted in the inkjet recording device of 4th Embodiment of this invention, and a conveyance member. It is a side view which shows the outline of the inkjet recording head mounted in the inkjet recording device of 5th Embodiment of this invention, and a conveyance member. It is a perspective view which shows the mechanism to which the transfer roller mounted in the inkjet recording device of 5th Embodiment of this invention is moved. It is a flowchart which shows the printing operation | movement of the inkjet recording device of 5th Embodiment of this invention.

Explanation of symbols

10 Inkjet recording device (droplet discharge head)
30 Conveying belt (conveying member)
46 Guide member (contact means, lifting mechanism)
48 Ball screw (contacting means, lifting mechanism)
54 Gear (contact means, lifting mechanism)
56 Motor (contact means, lifting mechanism)
58 Gear (contact means, lifting mechanism)
60 Belt cleaning unit (cleaning member)
70 Pressing member (elastic member)
72 Oil application unit (contacting means)

Claims (9)

A droplet discharge head having a nozzle surface on which nozzles for discharging droplets are formed;
It has a droplet ejection area where droplets are ejected from the droplet ejection head, transports a recording medium to the droplet ejection area, or transfers droplets ejected to the droplet ejection area to the recording medium A conveying member to be
A close contact means for moving the droplet discharge head or the transport member to bring the transport member into close contact with the nozzle surface;
A droplet discharge apparatus comprising:   The transport member is a transport belt wound around a roller, and the contact means is configured to prevent the liquid contact until the nozzle contact surface of the transport belt to which the nozzle surface of the droplet discharge head comes into contact is lowered from the other belt surface. The droplet discharge apparatus according to claim 1, wherein the droplet discharge head or the transport member is moved.   The elastic member which contacts the said conveyance member when the said droplet discharge head or this conveyance member is moved is provided in the opposite side to the said droplet discharge area | region of the said conveyance member. The droplet discharge device according to claim 2.   The liquid droplet ejection apparatus according to claim 1, further comprising a cleaning member that cleans a surface of the transport member.   The liquid droplet ejection apparatus according to claim 1, wherein a seal liquid is applied to a surface of the transport member on which the nozzle surface is in close contact.   The droplet discharge device according to claim 5, wherein the seal liquid has a property of spreading with respect to the transport member.   7. The liquid droplet ejection apparatus according to claim 5, wherein the sealing liquid has a property of repelling the liquid ejected from the nozzle.   8. The liquid droplet ejection apparatus according to claim 5, wherein the seal liquid is incompatible with the liquid ejected from the nozzle. 9.   6. The liquid droplet ejection apparatus according to claim 5, wherein the seal liquid is a liquid ejected from the liquid droplet ejection head.

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