WO1999021721A1

WO1999021721A1 - Ink jet printer with pressure fluctuation damping device

Info

Publication number: WO1999021721A1
Application number: PCT/JP1998/002386
Authority: WO
Inventors: Tetsuya Yamamoto; Mizue Fukushima; Wataru Ito; Seiichi Osawa
Original assignee: Citizen Watch Co., Ltd.
Priority date: 1997-10-28
Filing date: 1998-05-29
Publication date: 1999-05-06
Also published as: AU7455298A

Abstract

A pressure fluctuation damping device installed between a printing head (16) and ink supply means (18) to damp pressure fluctuation generated in an ink supply passage (42). The device is provided with a base (104) having at least one wall surface (102) which can be disposed substantially along the direction of gravity, at least one recess (108) which is provided in the wall surface of the base and a portion of which acts as a bubble reservoir (106), an ink inflow passage (112) formed through the base, having at one end thereof an inflow port (114) provided away from the bubble reservoir in the recess, and connected at the other end thereof to the ink supply passage, an ink outflow passage (100) formed through the base, having at one end thereof an outflow port (120) provided away from the bubble reservoir and the inflow port in the recess, and connected at the other end thereof to the printing head, and a flexible sheet (110) fixed to the wall surface of the base so as to cover the recess. The inflow port and the outflow port are positioned below the bubble reservoir in the direction of gravity so as not to align with each other in the direction of gravity when the wall surface of the base is installed substantially along the direction of gravity. The flexible sheet is composed of a laminated film comprising a plurality of layers which are laminated one upon another and formed of functionally different materials.

Description

Description Inkjet printer with pressure fluctuation damping device Technical field

The present invention relates to a non-impact printer, and more particularly, to a pressure fluctuation damping device that attenuates and reduces pressure fluctuations of an ink in an ink supply system caused by acceleration during reciprocating movement of a print head. The present invention relates to an ink jet printer provided with a device. Further, the present invention relates to a pressure fluctuation damping device suitably used in an industrial ink jet printer. Background art

Non-impact printers are used in a variety of fields because they produce less noise when printing characters and images, and can perform color printing. Above all, an ink jet printer that prints by ejecting ink droplets from a large number of fine nozzles provided on the print head onto the material to be printed, especially an on-demand printer that uses a piezoelectric element for the print head Ink-jet printers of the print method can print on plain paper, and because the printer is easy to reduce the size of the printer, it is easy to reduce the size of the printer itself. It is becoming popular as an output device. On the other hand, the impact-type printer has advantages in running costs, such as easy maintenance due to its relatively simple structure, and inexpensive ink ribbon. It is widely used as an industrial printer such as a bankbook printer and a printer for printing slips (hereinafter simply referred to as a bankbook printer). However, in recent years, for example, in the field of passbook printers, the noise has been reduced, the size of the machine has been reduced, and the execution speed has been reduced (that is, collected after the user puts the passbook into the printer and then prints). And the need to improve the response time, and it is becoming difficult to satisfy them with an impact printer.

One of the issues to be solved when using an ink jet printer as an industrial printer is that pressure fluctuations that occur in the ink supply system due to the acceleration during the reciprocation of the print head There is a problem.

In conventional ink jet printers, for models that are expected to use a large amount of ink, such as for industrial use, a large-capacity ink storage unit is separated from the print head and installed on the printer body. A configuration is known in which an ink storage unit and a printing head are connected by an ink tube serving as a flexible ink supply line. In such a configuration, when the print head reciprocates along the predetermined print area during the printing operation, the ink in the ink tube is subjected to acceleration, and the pressure of the ink fluctuates. This pressure fluctuation affects the meniscus of the ink liquid surface formed near the nozzle opening of the print head, and as a result, the ink leaks from the nozzle due to the destruction of the meniscus, the ink leaks, or the like. Ink droplets are not formed properly due to the vibration of the meniscus during droplet ejection, causing a problem that characters and images cannot be printed accurately.

In order to solve this problem, there is a known ink jet printer in which a pressure fluctuation damping device for damping the ink pressure fluctuation is provided between the ink tube and the printing head. Have been. Japanese Utility Model Publication No. 3-5 4 9 14 discloses an ink jet printer equipped with such a pressure fluctuation damping device. As shown in Fig. 10, the pressure fluctuation damping device includes a base 3 internally provided with a branch path 1 branched from the ink supply path and a damper hole 2 provided vertically above the branch path 1, and a branch path 1 and a branch path 1. And a flexible member (5) that covers the damper hole (2) and is joined to the base (3) and that bends in the moving direction (A) of the print head (4). The pressure fluctuation generated in the ink tube 6 during the reciprocating movement of the print head 4 Is attenuated by the action of the air and the flexible member 5.

In the base 3, the inlet 7 and the outlet 8 of the ink are formed at almost the same height, and they are connected by a streamlined flow path. Therefore, the ink flow can be made smooth, and there is no place where the ink is stagnated, so that bubbles in the ink which adversely affect the ink jet printing function are quickly discharged to the damper hole 2. be able to. Also, the flow path to Dunbar Hall 2 was branched upward from the ink supply path connecting the ink inlet 7 and the ink outlet 8, so that it was mixed into the ink in the ink tube 6 during printing. The bubbles can be automatically raised to prevent the bubbles from being sent to the print head 4.

In the above configuration, when the ejection frequency of the ink droplets is low and the number of nozzles is not too large, the amount of ink supplied to the print head 4 is small, so that the ink flows from the ink inlet 7. By branching the flow path from the route to the outlet 8 to the damper hole 2, air bubbles mixed into the ink tube 6 during printing can be floated and the air bubbles can be captured in the damper hole 2. However, when the ink droplet ejection frequency is high and the number of nozzles is large, or when ink is suctioned from the nozzle surface by an external suction device to cure the clogging of the nozzle, the printing head is not used. Since the amount of ink supplied to the nozzle 4 increases, the flow of the ink in the path from the inlet 7 to the outlet 8 becomes faster, and the air bubbles in the ink tube 6 do not rise and become heads. It may leak to the side. As a result, ink droplets may not be able to be ejected normally from the nozzle into which the bubbles have entered.

Further, in the above configuration, the ink liquid surface 9 which forms the boundary between the air in the damper hole 2 and the ink has a small area because it is formed in the branch passage 1. However, the ink pressure fluctuation is reduced by damping the vibration of the ink liquid level by the damping action of the air in the damper hole 2. In order to obtain a sufficient pressure fluctuation damping effect, it is desirable to increase the ink level. As a result, there is a fear that the overall size of the pressure fluctuation damping device will be increased.

In addition, in order to maintain the function of the pressure fluctuation damping device well over a long period of time, it is required that the structural parts that come into contact with the ink do not swell or dissolve due to the influence of the ink component. Is done. Also, depending on the field of application of the ink jet printer (for example, passbook printer), a pigment ink using a pigment may be used as a coloring agent. It is desired to suppress evaporation of water from the ink in the attenuator so that aggregation of the pigment does not occur. Disclosure of the invention

An object of the present invention is to effectively attenuate the pressure fluctuation of the ink generated in the ink supply path, and to surely capture air bubbles mixed in the ink in the ink supply path. Accordingly, it is an object of the present invention to provide an ink jet printer having a pressure fluctuation damping device capable of preventing defective ejection of ink droplets and suppressing an increase in the size of the device.

Another object of the present invention is to provide a pressure fluctuation damping device for an ink jet printer which can maintain the function of damping the pressure fluctuation of the ink in the ink supply path for a long period of time. It is to be.

In order to achieve the above object, the present invention provides an airframe having an airframe, a plurality of nozzles for ejecting ink droplets, and at least one nozzle surface on which the nozzles are opened. A print head installed so as to be able to reciprocate in a predetermined direction with an ink supply means having an ink supply path for supplying ink to the print head; and a print head and an ink. A pressure fluctuation attenuator installed between the supply means and the ink supply passage, the pressure fluctuation attenuator being configured to attenuate the pressure fluctuation generated in the ink in the ink supply path. A base that has at least one wall that can be placed along the direction of gravity, and at least one depression that is recessed in the wall of the base and partly acts as a bubble reservoir. One end has an inflow port that is formed through and is provided in the recess and is separated from the bubble reservoir, and has an inflow path that is connected to the ink supply path at the other end, and a through hole formed at the base. An ink outlet is provided at one end of the recess, and is provided apart from the air bubble reservoir and the inlet, and the other end is connected to the print head at an ink outlet passage, and the base is formed so as to cover the recess. A flexible sheet fixed to the wall surface of the airbag, wherein when the wall surface is installed substantially along the direction of gravity, the inflow port and the outflow port are located below the bubble reservoir in the direction of gravity. Inks placed so that they do not line up with each other in the direction of gravity The Tsu Topuri printer to provide.

In the above configuration, it is preferable that the air bubble reservoir of the pressure fluctuation damping device is further recessed in the depression.

In addition, it is preferable that a linearly extending wall, which is a part of the peripheral wall defining the depression, is formed between the inflow port of the pressure fluctuation damping device and the bubble reservoir.

The pressure fluctuation damping device is fixedly incorporated in the print head, and the base wall can be arranged substantially parallel to the reciprocating direction of the print head. Three subheads each having a surface, the ink supply means includes three ink supply paths for supplying ink to each of the three subheads, and the pressure fluctuation damping device includes: , Three subheads and three depressions individually connected to each of the three ink supply paths.

In this case, the base of the pressure fluctuation damping device has a pair of wall surfaces arranged apart from each other, and three recesses are distributed to the pair of wall surfaces. You can get it.

Advantageously, the base of the pressure fluctuation damper is formed from polypropylene.

The flexible sheet of the pressure fluctuation damping device preferably has at least a surface facing the depression formed of polypropylene.

Further, it is advantageous that the flexible sheet of the pressure fluctuation damping device is composed of a laminated film having a plurality of layers formed of functionally different materials laminated on each other.

The ink jet printer can be used as a passbook printer, and the present invention is a pressure fluctuation damping device for attenuating a pressure fluctuation generated in a fluid in a fluid flow path. A base having at least one wall that can be arranged along the direction of gravity, at least one depression that is recessed in the wall of the base, and a part of which acts as a bubble reservoir, A fluid inflow passage connected to an external fluid flow path at one end, and a fluid inflow passage connected to an external fluid flow path at the other end; A fluid outlet channel connected to an external fluid flow path at one end, and a fluid outlet channel connected to an external fluid flow path at the other end, and a recess. A flexible sheet fixed to the wall surface of the base. When the wall surface is arranged substantially along the direction of gravity, the pressure fluctuation damping device is arranged below the bubble reservoir in the direction of gravity and at a position where the inlet and the outlet are not aligned with each other in the direction of gravity. I will provide a.

It is preferable that the bubble reservoir be further recessed in the depression. It is preferable to form a linearly extending wall that is a part of the peripheral wall that defines the depression between the inflow port and the bubble reservoir.

The flexible sheet should have at least the surface facing the depression identical to the base. Advantageously, it is formed from a material.

Preferably, the base is formed from polypropylene.

Advantageously, at least the surface of the flexible sheet remote from the depression is made of a material having excellent heat resistance.

The flexible sheet is preferably made of a laminated film having a plurality of layers formed of functionally different materials laminated on each other. The flexible sheet preferably has elasticity. BRIEF DESCRIPTION OF THE FIGURES

The above and other objects, features and advantages of the present invention will be described based on embodiments shown in the accompanying drawings. In the attached drawing,

FIG. 1 is a schematic perspective view showing main components of an ink jet printer according to an embodiment of the present invention in a partially transparent view.

FIG. 2A is a schematic perspective view showing an external configuration of a print head of the ink jet printer of FIG. 1,

FIG. 2B is a schematic perspective view showing some components of the print head of FIG. 2A. FIG. 3 is an exploded view of a sub-head constituting a print head of the ink jet printer of FIG. Perspective view,

Fig. 4 is a sectional view of the sub-head of Fig. 3 when assembled.

FIG. 5 is an exploded perspective view showing some components of the print head of FIG. 2A, FIG. 6 is an exploded perspective view showing a pressure fluctuation damping device according to one embodiment of the present invention together with a sub head,

FIG. 7 is a partially enlarged perspective view of the pressure fluctuation damping device of FIG. 6,

FIG. 8 is an exploded perspective view of the pressure fluctuation damping device of FIG. 6,

FIG. 9 is a schematic perspective view showing the pressure fluctuation damping device of FIG. 6 incorporated in a printing head, and FIG. 10 is an exploded perspective view showing a conventional pressure fluctuation damping device.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to the drawings, FIG. 1 is a schematic perspective view showing an ink jet printer 10 including a pressure fluctuation damping device according to an embodiment of the present invention, in which some main components are partially shown in a perspective view. .

The ink jet printer 10 includes an openable and closable housing 12 and an airframe 14 including a frame (not shown), and a predetermined direction within the airframe 14 (usually a horizontal direction with respect to the printer installation reference plane). ) The print head 16 is installed so that it can move back and forth, the ink supply means 18 has an ink supply path that supplies ink to the print head 16, and the machine frame 1 The material feed means 20 for feeding the printing material (not shown) to the print area P facing the print head 16 in 4 and the print head 16 reciprocating in the machine frame 14 And a maintenance means 22 having a plurality of functional stations distributed in both end regions of the moving range. The print head 16 is fixed to the carriage 24, and the carriage 24 slides axially on the guide bar 26 extending in the horizontal direction in the body frame 14. Carried as possible. During the printing operation, the print head 16 is reciprocated in the same horizontal direction along the guide bar 26 by a drive mechanism (not shown).

As schematically shown in FIGS. 2A and 2B, the print head 16 has a plurality of nozzles 28 for ejecting ink droplets, and a nozzle surface 30 on which the nozzles 28 open. And an actuator 32 comprising a piezoelectric element for ejecting ink droplets from the nozzles 28. In the illustrated embodiment, the printhead 16 has three independent subheads 34, each of which has a plurality of nozzles 28, a nozzle face 30 and a nozzle face 30. A function unit 32 is provided. Between the ink supply means 18 and the three sub-heads 34 of the print head 16, the pressure fluctuation generated in the ink in the ink supply path is attenuated, and each nozzle is reduced. 28 Pressure fluctuation damping device or damper described later to stabilize the meniscus of the ink that has entered the inside

3 6 is installed. FIGS. 1 and 2A show a flexible circuit board 38 for applying a drive voltage to the actuator 32. In addition, the sub-head 34 and the pressure fluctuation damping device 36 are usually covered with a cover 39 which is attached to the carriage 24 so as to be openable and closable.

As shown in FIG. 1, the ink supply means 18 includes an ink storage section 40 installed at a position away from the print head 16 in the body frame 14 and a print head 16. Supply line connecting the ink storage unit 40

In the printing operation, a quick-drying pigment ink is supplied to the printing head 16. In the illustrated embodiment, the ink supply line 42 is formed from a tube that is sufficiently flexible so as not to impede the reciprocation of the print head 16.

In the illustrated embodiment, the ink supply means 18 includes three independent ink storage units 40, and each ink storage unit 40 and each sub head 36 of the print head 16. And three independent ink supply lines 42 (FIG. 2A). Therefore, the ink jet printer 10 can be used as a color printer. Further, in the illustrated embodiment, the three ink storage sections 40 are formed in a cartridge type ink tank 44 that is detachably mounted at a predetermined position of the body frame 14. . The number of the sub heads 36, the ink storage units 40, and the ink supply pipes 42 is not limited to three, and can be variously selected.

The material feeding means 20 installed below the reciprocating movement range of the printing head 16 has an upper fixed plate 46 and a lower movable plate 48. A material holding portion 50 for holding a printing material such as printing paper or a passbook inserted between the plates 46 and 48, and a material holding portion provided above the fixed plate 46. A correction mechanism 52 that corrects the feed direction of the printing material sandwiched between 50 and the correction mechanism 52 is installed above the fixed plate behind the material feed direction of the correction mechanism 52, and is held by the material holding section 50. A feeding mechanism 54 is provided for feeding the material to be printed into the printing area P and discharging the material from the printing area P.

The print area P is formed between two pairs of feed rollers 56 forming the feed mechanism 54. The print head 16 reciprocates along the guide bar 26 above the print area P, and scans the printing material fed into the print area P while scanning a plurality of nozzles 28. By ejecting ink droplets from above, characters and images are formed on the printing material.

The plurality of functional stations constituting the maintenance means 22 are provided with a plurality of nozzles 28 opening to the nozzle surface 30 of the print head 16 substantially closed when the printer is not used. Nozzle 58 that seals to prevent the ink in nozzle 28 from drying out when coated, and ink that thickens in nozzle 28 of print head 16 when the printer is not in use. 28 Remove the suction station 60 that discharges 8 pieces of ink and the ink that has thickened in the nozzles 28 of the print head 16 while the printer is not in use by suction, and clean the nozzle surface 30. And a purifying station 62 for wiping the nozzle surface 30. In the illustrated embodiment, the closing station 58 and the discharging station 60 are provided at one end (right end in the figure) of the reciprocating movement range R of the printing head, and the cleaning station 62 is provided. Is set at the other end (left end in the figure) of the reciprocating range R of the print head.

Such a decentralized arrangement of various functional stations makes effective use of the idle space in the body frame 14 of the ink jet printer 10. In other words, the print head is generally used for an ink jet printer. Since the printing is performed on the material to be printed during the reciprocating movement in the predetermined direction, the reciprocating range of the printing head is set to be wider than the dimension of the material feeding means facing the printing head. As a result, an idle space is inevitably formed around the material feeding means. In the ink jet printer 10, the various functional stations described above, which realize a multifunctional maintenance system, are distributed in such an idle space to increase the body size. It is effectively preventing it. In addition, the ink jet printer 10, which has a multifunctional maintenance system, can use a quick-drying pigment ink safely, and therefore can be used as an industrial printer such as a passbook printer. It can be suitably used.

In the ink jet printer 10 having the above configuration, the inertia force is applied to the ink supply path, particularly the ink in the ink supply pipe 42, by the acceleration of the print head 16 during the reciprocating movement. Pressure fluctuation based on the pressure. Therefore, the ink jet printer 10 includes a pressure fluctuation damping device 36 for attenuating and mitigating such pressure fluctuation of the ink between the ink supply line 42 and the sub-head 34. Installed in Hereinafter, with reference to FIGS. 3 to 9, the configurations of the sub-heads 34 of the print head 16 and the pressure fluctuation damping device 36 according to an embodiment of the present invention will be described in more detail. explain. FIG. 3 is an exploded perspective view of the sub head 34, and FIG. 4 is a sectional view of the sub head 34. As shown in the figure, a plurality of pasty-shaped piezoelectric material plates 64 having a piezoelectric effect of, for example, about 20 m, and a plurality of pasted electrode layers 66 mainly containing silver and palladium are sequentially provided. After lamination, the laminate is fired to form a laminated piezoelectric body 68. The electrode layers 66 are arranged on both sides of each piezoelectric material plate 64, and are connected to a collector electrode 70 a provided on one side end surface of one of the electrode layers 66 and the laminated piezoelectric body 68, and Electrode layer 66 is connected to the collector electrode 70 b provided on the other side end face of the laminated piezoelectric body 68. Connected. Each of the collecting electrodes 70a and 70Ob is formed by sequentially depositing chromium, nickel, and gold on the laminated piezoelectric body 68 by a thin film forming method such as a vacuum evaporation method. When a voltage is applied between the collecting electrode 70a and the collecting electrode 70b of the laminated piezoelectric body 68, an electric field is generated in each piezoelectric material plate 64 and each piezoelectric material plate 64 is moved in the thickness direction (in the figure). Slightly up and down. Then, the increase in the thickness of each piezoelectric material plate 64 accumulates, and the laminated piezoelectric body 68 is displaced by a required amount in the thickness direction.

The laminated piezoelectric body 68 is adhered on a substrate 72 made of an insulating material such as a ceramic. Further, by forming a groove from the upper surface of the laminated piezoelectric body 68 by a mechanical processing means such as a wire saw, a plurality of laminated piezoelectric elements 74 that can independently drive the laminated piezoelectric body 68 (i.e., actuators). 3 2) Thus, the piezoelectric element unit 76 is formed. Power from the outside is supplied to each laminated piezoelectric element 74 by a flexible circuit board 78. In the flexible circuit board 78, the linear contacts 78a formed by stripping the vicinity of the ends of the flexible circuit board 78 are connected to the collecting electrodes 70a and 70b of each laminated piezoelectric element 74 by soldering. It is electrically connected by a method such as attachment.

In the piezoelectric element unit 76, a plurality of laminated piezoelectric elements 74 are inserted into an opening 82 provided at the center of a fixing member 80 made of a resin material, and received by the fixing member 80. After arranging the free end face of each laminated piezoelectric element 74 on the side away from the substrate 72 and the upper surface of the fixing member 80 on the same plane, it is bonded to the gap between the substrate 72 and the fixing member 80. Then, the piezoelectric element unit 76 is fixed to the fixing member 80 by filling with the agent.

On a flat surface formed by the upper surface of the fixing member 80 and the free end surface of each laminated piezoelectric element 74, a thin diaphragm 84 is laminated and fixed. The vibration plate 84 is a nickel plate formed by an electrolysis method and having a thickness of about several meters. In addition, on the diaphragm 84, each laminated piezoelectric element 74 A resin flow path substrate 90 having a piezoelectric chamber 86 and an ink supply port 88 is bonded. A nozzle plate having a large number of nozzles 28 formed on the end face of each unit produced in this manner, on the opposite side of the ink supply port 88 from which each piezoelectric chamber 86 opens. 2 is bonded, and sub-head 34 is completed. Although FIG. 3 shows a simplified four-channel configuration having four laminated piezoelectric elements 74 and four pressure chambers 86, the actual subhead is 20 to 50 channels. It has a channel configuration.

The sub-head 34 formed in this way is received in the receiving portion 94a of the frame 94 made of a resin material, as shown in FIG. The frame body 94 has three openings 96 on the bottom wall (FIG. 2B), and the nozzle plate 92 of the three sub-heads 34 is aligned with each opening 96. Be placed. The three sub-heads 34 are positioned so that the nozzle faces 30 of the respective nozzle plates 92 are located on the same plane within the frame body 94, and the frame body 94 is formed by an adhesive. Fixed to

As shown in FIG. 6, the three sub-heads 34 accommodated in the frame 94 are connected to the respective ink supply ports 88 through the couplers 98 made of rubber or the like. The ink outflow channel 100 of the damping device 36 is connected. Here, the ink jet printer 10 according to the present embodiment has a nozzle surface 30 of each sub-head 34 of the print head 16, and is horizontal with respect to the printer installation reference surface. In addition, it is arranged so as to face down and perform printing. Therefore, the vertical direction in FIG. 6 is the direction of gravity when the printer is actually installed, and the pressure fluctuation damping device 36 can exert a normal pressure fluctuation damping function when in the posture shown in the figure.

The pressure fluctuation damping device 36 includes a base 104 having at least one wall 102 arranged in the illustrated posture substantially along the direction of gravity, and a wall 100 of the base 104. 2 and partially covers at least one depression 108 and depression 108 acting as bubble reservoir 106 And a flexible sheet 110 fixed to the wall surface 102 of the base 104 as described above. In the illustrated embodiment, the base portion 104 has a pair of wall surfaces 102 a and 102 b that are arranged outwardly away from each other, and the pair of wall surfaces 102 a and 102 b Are provided with three depressions 108 in a distributed manner.

As shown in FIG. 7 in an enlarged manner, the pressure fluctuation damping device 36 is further formed through the base 104, opens into the recess 108 at one end, and opens into the base 104 at the other end. An ink inflow passage 112 that opens to the upper surface and a through hole also formed in the base 104, with one end opening into the depression 108 and the other end opening into the lower surface of the base 104 And an ink outflow path 100. One end of the ink inflow channel 112 defines an inflow port 114 provided in the recess 108 and spaced apart from the bubble reservoir 106. The other end of the ink inlet channel 112 defines an inlet 118 connected to the ink supply line 42 via the coupler member 116 (FIG. 2B). One end of the ink outflow passage 100 defines an outlet 120 provided in the recess 1108 so as to be separated from both the air bubble reservoir 106 and the inlet 114. The other end of the ink outlet channel 100 defines an outlet 122 connected to the sub-head 34 via the coupler 98.

Then, when each wall 102a, 102b of the base 104 is pushed down by 15 pounds substantially along the direction of gravity, the inlet 1114 of the ink inlet channel 112 and the ink outlet The outlet 120 of the channel 100 is located below the bubble reservoir 106 in the dent 110 in the direction of gravity, and not aligned with each other in the direction of gravity. Be placed.

In the illustrated embodiment, three ink inflow channels each individually connected to each of the three recesses 108 formed in each wall 102 a, 102 b of the base 104. 1 1 2 and the ink outflow channel 100 are provided, and the ink inflow channel 1 12 and the ink outflow channel 100 each have three ink supply channels. Independently connected to feed line 42 and three subheads 34.

Further, in the illustrated embodiment, the bubble reservoir 106 is recessed further deeper from the recess 108 along one edge of the recess 108. In the recess 108, between the inflow port 114 and the bubble reservoir 106, a linearly extending wall 108a, which is a part of the peripheral wall that defines the recess 108, is formed. Is formed. In addition, as shown in the exploded view in FIG. 8, the ink outlet 120 is a D-shaped recess slightly recessed from the recess 108 at a position below the bubble reservoir 106 in the direction of gravity. Are located in the recesses 1 2 4. In the recess 108, a filter 126 having a mesh of 10 micron is applied so as to cover the D-shaped recess 124.

The flexible sheet 110 is fixed to both side walls 102 a and 102 b of the base 104 by, for example, heat fusion. In the illustrated embodiment, a relatively large-sized flexible sheet 110a is fixed to a wall 102a on which two recesses 108 are disposed, and a wall 1102 on which one recess 108 is disposed. A relatively small-sized flexible sheet 110b is fixed to 02b. In this way, the depressions 108 cooperate with the flexible sheet 110 to form a damper chamber that attenuates and reduces the pressure fluctuation of the ink in the ink supply path.

As shown in FIG. 9, the pressure fluctuation damping device 36 having the above configuration is fixed to a frame 94 accommodating three sub-heads 34 and attached to a carriage 24. Mounted fixedly. At this time, as shown in the figure, the depressions 108 formed in each wall 102 of the base 104 of the pressure fluctuation damping device 36 Forced in the direction of the reciprocating movement of the printing head 16 (arrow B in the drawing). Are arranged in parallel. That is, as shown in FIG. 6, three recesses 108 are formed by a pair of wall surfaces 102 a, 102 b extending in a direction parallel to the direction in which the three sub heads 34 are arranged in parallel. Is formed along. Such a configuration not only facilitates the thinning of the base 104 of the pressure fluctuation attenuating device 36, but also has the effect of reducing the size of the printing head 16 in the depth direction. The operation of the pressure fluctuation damping device 36 having the above-described configuration is performed during the printing operation by the printing head 16 described below, or from the nozzle 28 by the cleaning station 62 of the maintenance means 22. During the suction removal operation of the ink, the ink is supplied from the ink storage unit 40 to the respective sub-heads 34 via the respective ink supply lines 42 and the pressure fluctuation damping device 36. . At this time, as shown by the dashed arrow in FIG. 7, the ink flows from each inlet 1 18 opened on the upper surface side of the base 104 of the pressure fluctuation damping device 36 to each ink inflow passage 1 1 2 And flows from each inlet 1 14 into each recess 1 08. In the recess 108, air stays in the bubble reservoir 106, and a desired shape meniscus is formed on the ink liquid surface that forms a boundary between the staying air and the ink.

When ink is first filled in each recess 108, the air in the recess 108 is sucked out of the ink outflow passage 100 to remove the air into the bubble reservoir 106. The ink fills the depression 108 with the air remaining partially. When the suction of air is stopped, the negative pressure in the air bubble reservoir 106 becomes approximately equal to the pressure in the ink reservoir 40, and the volume of air in the air bubble reservoir 106 is reduced. The recess 108 is made shallow and the bubble reservoir 106 is deeply recessed to secure the volume of ink to be filled in the recess 108 and the outlet 120 is filled in the bubble reservoir 1. When placed below the gravitational direction of 06, after filling the ink, the liquid level of the ink rises to a stable position above the outlet 120. Therefore, the stagnant air in the air bubble reservoir 106 does not flow out of the outlet 120 due to the negative pressure of the ink generated by the normal printing operation.

For example, air bubbles generated in the ink in the ink supply line 42 by the reciprocating operation of the print head 16 are depressed from the ink inflow channel 112 through the inlet 114 with the ink supply. Invade 1 08. Penetration into depression 1 08 The ink that has flowed smoothly flows in the direction regulated by the peripheral wall including the wall 108a, and by the time it reaches the outlet 120, the air bubbles that have entered the ink are naturally levitated. Remove from ink and collect in bubble reservoir 106. At this time, the volume of the damper chamber was secured by making the depression 108 thin and wide, so that the inlet 114 and the outlet 120 could be sufficiently separated from each other, and therefore the ink flow rate Even when there is a large amount of ink, the ink does not flow from the inlet 114 to the outlet 120 immediately. As a result, before the ink reaches the outlet 120, the air bubbles are surely removed from the ink by automatic levitation and collect in the air bubble reservoir 106. The straight wall 108a is effective for the air bubbles to propagate along the wall 108a and quickly float to the air bubble reservoir 106 without being affected by the ink flow rate.

Furthermore, by forming the depression 108 thin and wide, the ink liquid boundary between the ink in the depression 108 and the air in the air bubble reservoir 106 becomes flush with the ink flow. The road is relatively large. Therefore, for example, the pressure fluctuation of the ink in the ink supply line 42 caused by the reciprocating operation of the print head 16 causes the relatively large ink liquid level to cause a change in the pressure in the bubble reservoir 106. Compresses and expands air. As a result, due to the cooperation between the air in the bubble reservoir 106 and the flexible sheet 110, the vibration of the ink liquid surface is extremely effectively damped, and the pressure fluctuation of the ink is reliably reduced. Attenuated and relaxed.

The pressure fluctuation damping device according to the present invention can be formed from various materials having the characteristics described below in order to maintain the pressure fluctuation damping function well over a long period of time.

First, the base 104 of the above-described pressure fluctuation damping device 36 is formed of a material having excellent chemical resistance such that the portion in contact with the ink does not swell or dissolve due to the influence of the ink component. It is preferable to Also When a pigment ink is used, it is preferably formed of a material having low water vapor permeability in order to suppress evaporation of water from the ink so that aggregation of the pigment does not occur. Considering the moldability for forming a complicated flow channel structure, polypropylene (polypropylene) is a particularly suitable material.

P P).

It is desired that the flexible sheet 110 fixed to the base 104 satisfy the following various required characteristics, and films having the respective functions are laminated by various methods. It is advantageous to form it from a laminated film.

The characteristics required for the flexible sheet 110 are typically as follows:

(1) that it can be firmly fused to the base 104;

(2) No deformation or melting of the flexible part during heat fusion;

(3) moderately soft and elastic (Damba effect);

(4) Excellent chemical resistance (the same reason as for base 104), and

(5) excellent resistance to water vapor transmission;

Is mentioned.

In order to realize the characteristic (1), the surface to be bonded to the base 104 is formed of the same material as the base 104. Therefore, when the base 104 is made of polypropylene, the adhesive layer to the base 104 is formed from polypropylene. In particular, in consideration of deformation of the flexible sheet 110 due to fusion, it is desirable to use cast polypropylene (CPP).

In order to realize the characteristics of (2), the surface that comes into contact with the fusion jig should be made of polyethylene terephthalate (PET), polyvinylidene dendrite, or polyethylene terephthalate (PET). It is formed from a film with excellent heat resistance, such as KPET) and polyamide (trademark: NIPPON).

To realize the characteristic of (3), the total thickness of the laminated film must be 100 m or less.

In order to realize the characteristic (4), when the base 104 is made of polypropylene, the layer that contacts the ink (the same layer as the adhesive layer) is formed of polypropylene.

In order to realize the characteristics of (3), unlike the base part 104, it is not possible to obtain the water vapor transmission resistance due to the thickness of the material, so the water vapor transmission resistance is as high as possible even with a thin film. It is necessary to consist of materials. Therefore, as a layer other than the layer for ensuring the heat resistance described in (2), for example, at 40 ° C and a humidity of 90%, a permeability of 10 g · 30 um / m-24 hours is used. It is desirable to have humidity. Suitable materials include cast polypropylene (CPP), biaxially oriented polypropylene (◦PP), polychloride vinylidene (PVDC), and the like.

When the composition of the laminated film suitable as the flexible sheet 110 is shown by a combination of the various materials described above, for example, a CP PZO PP / KPET laminated film, a CPPZPVDC / PET laminated film, CPP 0 PP / PVDCZPET laminated film, CPP / OP PZ nylon / PET laminated film.

The properties that can be selectively added to the above properties include (6) excellent air permeation resistance. Such materials include, for example, polyvinylidene chloride (PVDC), ethylene vinyl alcohol copolymer (EVOH), polyamide (trademark: nylon) and the like.

In consideration of water vapor permeability and air permeability, the preferred laminated film configuration as flexible sheet 110 is as follows: CPP / EVOH ZK PET laminated film, CPP / 0 PP / EV〇 H / PET laminated film, CPP / OPP / Nylon ZK PET laminated film, the surface of the part that comes into contact with the base 104 ink It is preferable to perform hydrophilic treatment by oxidation, acid treatment, plasma treatment or the like. Industrial applicability

ADVANTAGE OF THE INVENTION The pressure fluctuation attenuation apparatus which concerns on this invention can attenuate the pressure fluctuation of the fluid which arose in the fluid flow path effectively, and can capture the air bubble mixed in the fluid in the fluid flow path reliably. In addition, since it is possible to suppress an increase in the size of the device, the device can be suitably used as a pressure fluctuation damping device for preventing poor ink injection at an ink jet print. Further, there is provided a pressure fluctuation damping device of an ink jet printer which can maintain a function of attenuating the pressure fluctuation of the ink in the ink supply path for a long period of time. INDUSTRIAL APPLICATION This invention is utilized effectively for industrial printers, such as a passbook printer using a pigment ink, for example.

Claims

The scope of the claims

1. Airframe and

A plurality of nozzles for ejecting ink droplets, and at least one nozzle surface on which the nozzles are opened, and a printing head installed so as to be able to reciprocate in a predetermined direction in the body frame. ,

An ink supply unit having an ink supply path for supplying ink to the printing head;

A pressure fluctuation attenuating device installed between the printing head and the ink supply means, for attenuating pressure fluctuations generated in the ink in the ink supply path;

The pressure fluctuation damping device,

A base with at least one wall that can be positioned substantially along the direction of gravity;

At least one depression recessed in the wall surface of the base, a portion of which acts as a bubble reservoir;

One end has an inflow port formed through the base and spaced apart from the bubble reservoir in the recess, and the other end is connected to the ink supply path. Road and

The base has a through hole formed at one end thereof, and an outlet provided at a distance from the bubble reservoir and the inlet in the recess, and is connected to the printing head at the other end. The ink outflow channel,

A flexible sheet fixed to the wall surface of the base so as to cover the depression,

When the wall is installed substantially along the direction of gravity, the inflow port and the outflow port are arranged so as not to be aligned with each other in the direction of gravity below the bubble accumulating portion. Inkjet printer.

2. The ink jet printer according to claim 1, wherein the bubble reservoir of the pressure fluctuation damping device is further recessed in the depression.

3. The ink jet printer according to claim 1, wherein a linearly extending wall that is a part of a peripheral wall that defines the depression is formed between the inflow port of the pressure fluctuation damping device and the bubble reservoir.ヱ Print printer.

4. The pressure fluctuation damping device is fixedly incorporated into the printing head, and the wall surface of the base is disposed substantially parallel to a reciprocating direction of the printing head. Inkjet printer.

5. The printing head includes three sub-heads each having the nozzle and the nozzle surface, and the ink supply means includes an ink for each of the three sub-heads. And three pressure supply damping devices, each of which is individually connected to each of the three sub-heads and each of the three ink supply paths. An ink jet printer according to claim 1, comprising a depression.

6. The method according to claim 5, wherein the base portion of the pressure fluctuation damping device has a pair of the wall surfaces arranged apart from each other, and the three depressions are provided by being distributed to the pair of wall surfaces. Ink jet printer.

7. The ink jet printer according to claim 1, wherein the base of the pressure fluctuation damping device is formed of polypropylene.

8. The ink jet printer according to claim 7, wherein the flexible sheet of the pressure fluctuation damping device has at least a surface facing the recess formed of polypropylene.

9. The flexible sheet according to claim 1, wherein the flexible sheet of the pressure fluctuation damping device is a laminated film including a plurality of layers formed of functionally different materials laminated on each other. Ink jet printer.

10. The ink cartridge according to claim 9, which is used as a passbook printer. Ettoprinter.

1 1. A pressure fluctuation attenuator that attenuates the pressure fluctuation generated in the fluid in the fluid flow path,

A fluid inflow passage formed at one end of the base portion and having an inflow port provided in the recess and spaced apart from the bubble reservoir, and having the other end connected to an external fluid flow path;

The base has a through hole formed at one end, and an outlet provided in the recess so as to be separated from the bubble reservoir and the inlet, and the other end is connected to an external fluid flow path. A fluid outflow channel;

When the wall surface is arranged substantially along the direction of gravity, the inlet and the outlet are arranged at positions below the bubble reservoir and in the direction of gravity, and are not aligned with each other in the direction of gravity.

Pressure fluctuation damping device.

12. The pressure fluctuation damping device according to claim 11, wherein the bubble reservoir is further recessed in the depression.

13. The pressure fluctuation damping device according to claim 11, wherein a linearly extending wall which is a part of the peripheral wall defining the depression is formed between the inflow port and the bubble reservoir.

14. The pressure fluctuation attenuating device according to claim 11, wherein the flexible sheet has at least a surface facing the depression formed of the same material as the base.

15. The pressure fluctuation damping device according to claim 14, wherein the base is formed of polypropylene.

16. The pressure fluctuation damping device according to claim 11, wherein at least a surface of the flexible sheet remote from the depression is formed of a material having excellent heat resistance.

17. The pressure fluctuation damping device according to claim 11, wherein the flexible sheet is formed of a laminated film including a plurality of layers formed of functionally different materials laminated on each other.

18. The pressure fluctuation damping device according to claim 11, wherein the flexible sheet has elasticity.