JP6355164B2 - Droplet discharge device - Google Patents

Description

  The present invention relates to a droplet discharge device, and more particularly to a droplet discharge device including a damper.

  The droplet discharge device is a device that discharges minute droplets from a nozzle. An ink jet printer is known as an apparatus for printing an image on a medium using such a droplet discharge device. In an ink jet printer, fine ink droplets are ejected from an ink jet head, which is a liquid droplet ejection head, toward a medium, and an image is recorded on the medium. There are two types of ink jet printer printing methods: a method of printing an image by reciprocating a print head, and a method of printing an image only by transporting a medium while the print head is fixed. The former is called a scan method, a shuttle method, etc., and the latter is called a single pass method, a one pass method, etc. A single-pass printer is called a line printer, and a print head mounted on the printer is called a line head.

  In the single-pass method, an image is printed only by transporting the medium, so a print head having a length corresponding to the width of the medium to be printed is required. Its manufacture becomes difficult as the width of the media to be printed increases. Therefore, as a method of manufacturing a print head used in a single-pass inkjet printer, a technique for manufacturing a print head having a desired width by connecting a plurality of short print heads is known. The short print head constituting the print head is called a head module and can function as a print head alone. Therefore, an ink supply port is individually provided. A head module of a print head that circulates and supplies ink is individually provided with an ink supply port and a discharge port.

  By the way, in order to print a high-quality image in an ink jet printer, it is necessary to control ink ejection correctly. In order to correctly control ink ejection, it is necessary to suppress ink pressure fluctuations as much as possible.

  Japanese Patent Application Laid-Open No. 2004-228561 proposes a technique for suppressing ink pressure fluctuation by installing a damper in an ink flow path. Patent Document 2 proposes a technique for suppressing ink pressure fluctuation by installing a damper for each head module in a print head configured by connecting a plurality of head modules.

JP 2009-101516 A JP 2014-233937 A

  However, in a print head configured by connecting a plurality of head modules, if a damper is installed for each head module, there is a drawback that the head becomes large and the head modules cannot be arranged at high density. Further, in a print head configured to circulate and supply ink, in order to effectively suppress pressure fluctuation, it is necessary to install a damper in each of the ink supply side flow path and the discharge side flow path. If a damper is installed in each flow path on the supply side and the discharge side, there is a disadvantage that the head further increases in size.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a liquid droplet ejection apparatus that can effectively suppress fluctuations in liquid pressure with a compact configuration.

  (1) A droplet comprising a nozzle and a supply port and a discharge port for liquid ejected from the nozzle, and configured by connecting a plurality of head modules to which liquid is circulated and supplied through the supply port and the discharge port. A discharge side, a liquid supply unit that circulates and supplies liquid to each head module that constitutes the droplet discharge head, and a supply side that is provided in a flow path on the supply side of each head module that constitutes the droplet discharge head A droplet discharge apparatus comprising: a damper; and a discharge-side damper that is provided in a discharge-side flow path of each head module constituting the droplet discharge head and is configured by a damper having a smaller damper capacity than the supply-side damper .

  According to this aspect, in the liquid droplet ejection head configured by connecting a plurality of head modules to which liquid is circulated and supplied, the supply side damper is provided in the flow path on the supply side of each head module, and the discharge is performed. A discharge damper is provided on the side flow path. The discharge-side damper is constituted by a damper having a smaller damper capacity than the supply-side damper. In a droplet discharge head configured to circulate and supply liquid to be discharged from a nozzle, the flow rate of liquid on the supply side is greater than the flow rate of liquid on the discharge side due to the discharge from the nozzle. As a result, the influence on the pressure fluctuation is larger on the supply side than on the discharge side. Therefore, in this mode, a damper with a large damper capacity capable of absorbing a large pressure fluctuation is installed on the supply side, while a damper with a small damper capacity is installed on the discharge side, so that the damper is appropriately arranged and the efficiency is improved. The pressure fluctuation is suppressed well.

  The damper can cope with a large pressure fluctuation as the damper capacity increases. On the other hand, the size of the damper increases as the damper capacity increases. According to this aspect, by making the damper capacity of the discharge side damper smaller than the damper capacity of the supply side damper, it is possible to make the whole compact while efficiently suppressing pressure fluctuation.

  Note that the flow path on the supply side refers to a flow path on the side that flows into the nozzle, that is, a flow path on the upstream side of the nozzle, in consideration of the circulation of the liquid. Therefore, when considered in units of head modules, it refers to a flow path on the side flowing into the head module. The flow path on the discharge side refers to the flow path on the side that flows out of the nozzle when the circulation of the liquid is considered, that is, the flow path on the downstream side of the nozzle. Therefore, when considered in units of head modules, it refers to the flow path on the side that flows out of the head module.

  (2) The supply-side damper is provided in a supply-side flow path disposed outside the head module, and the discharge-side damper is provided in a discharge-side flow path disposed outside the head module. ) Droplet discharge device.

  According to this aspect, the supply-side damper is provided in the supply-side flow path disposed outside the head module. In addition, a discharge-side damper is provided in the discharge-side flow path disposed outside the head module. That is, the supply side damper and the discharge side damper are arranged outside the head module.

  (3) The droplet discharge device according to (2), wherein the supply-side damper and the discharge-side damper are provided integrally with the head module.

  According to this aspect, the supply-side damper and the discharge-side damper that are individually arranged in each head module are integrally provided in the head module. As a result, the supply-side damper and the discharge-side damper can be arranged closer to the nozzle, and the pressure fluctuation accompanying the discharge of droplets can be effectively suppressed. It saves the trouble of installing a supply damper and a discharge damper separately.

  (4) The supply-side damper includes a damper film at least in part and a liquid chamber communicated with the supply port, and the liquid chamber is disposed inside the head module via a partition wall forming a part of the head module. The supply-side flow path and the liquid chamber, which are disposed adjacent to the supply-side flow path disposed in the interior of the head module and communicated with each other via an outflow passage formed in the partition wall, are connected to each other and discharged. The side damper is provided with a damper film at least partially and a liquid chamber communicated with the discharge port, and the liquid chamber is disposed inside the head module via a partition wall constituting a part of the head module. The above (3), wherein the discharge side flow path and the liquid chamber are disposed adjacent to the discharge side flow path and disposed inside the head module through an inflow path formed in the partition wall. Droplet discharge device.

  This aspect is an aspect when the supply side damper and the discharge side damper are integrally provided in the head module. The supply-side damper has a liquid chamber disposed adjacent to a supply-side flow path disposed inside the head module via a partition wall that forms a part of the head module. And it connects with the flow path of the supply side arrange | positioned inside the head module through the outflow path formed in the partition. In addition, the discharge-side damper has a liquid chamber disposed adjacent to a discharge-side flow path disposed inside the head module via a partition wall that forms a part of the head module. And it connects with the discharge side flow path arranged inside the head module via the inflow path formed in the partition.

  (5) The supply-side damper is provided in a supply-side flow path disposed inside the head module, and the discharge-side damper is provided in a discharge-side flow path disposed in the head module. ) Droplet discharge device.

  According to this aspect, the supply-side damper is provided in the supply-side flow path disposed inside the head module. In addition, a discharge side damper is provided in the discharge side flow path disposed inside the head module. That is, the supply side damper and the discharge side damper are disposed inside the head module. As a result, the supply-side damper and the discharge-side damper can be arranged in the vicinity of the nozzle, and the pressure fluctuation accompanying the discharge of the droplet can be more effectively suppressed.

  (6) The droplet discharge device according to (5), wherein the supply-side damper and the discharge-side damper are provided for each nozzle.

  According to this aspect, when the supply side damper and the discharge side damper are disposed in the head module, the supply side damper and the discharge side damper are provided for each nozzle. That is, the supply-side damper and the discharge-side damper are installed for each nozzle. Thereby, the pressure fluctuation near the nozzle can be effectively suppressed.

  (7) The droplet discharge device according to any one of (1) to (6), wherein the supply-side damper and the discharge-side damper are disposed in the vicinity of an actuator that discharges liquid from the nozzle.

  According to this aspect, the supply-side damper and the discharge-side damper are arranged in the vicinity of the actuator that discharges the liquid from the nozzle. Thereby, the pressure fluctuation accompanying discharge of a droplet can be controlled effectively. The actuator is, for example, a piezo element in the case of a piezo type droplet discharge head, and a heater in the case of a thermal type droplet discharge head.

  (8) When the wavelength of the pressure wave transmitted through the liquid is λ, the supply-side damper and the discharge-side damper are disposed within a range where the distance from the actuator is λ or less. apparatus.

  According to this aspect, when the wavelength of the pressure wave propagating in the liquid is λ, the supply-side damper and the discharge-side damper are arranged at positions within a range where the distance from the actuator is λ or less. Thereby, the pressure fluctuation accompanying discharge can be suppressed more effectively.

  (9) The ratio of the damper capacity of the supply side damper and the damper capacity of the discharge side damper is the same as the ratio of the flow rate of the liquid flowing through the supply side flow path and the flow rate of the liquid flowing through the discharge side flow path. The droplet discharge device according to any one of (1) to (8) above.

  According to this aspect, the ratio between the damper capacity of the supply side damper and the damper capacity of the discharge side damper is the same as the ratio of the flow rate of the liquid flowing in the supply side flow path and the flow rate of the liquid flowing in the discharge side flow path. Set to Thereby, according to the pressure fluctuation which arises, a supply side damper and a discharge side damper can be installed appropriately.

  (10) The supply-side damper and the discharge-side damper are droplets according to any one of (1) to (9), wherein the liquid chamber and the air chamber are dampers having a structure in which the liquid chamber and the air chamber are partitioned by an elastically deformable damper film. Discharge device.

  According to this aspect, the supply-side damper and the discharge-side damper are constituted by dampers having a structure in which the liquid chamber and the air chamber are partitioned by the elastically deformable damper film.

  (11) The droplet discharge device according to (10), wherein the air chamber of the supply-side damper and the air chamber of the discharge-side damper are communicated with each other via a communication unit.

  According to this aspect, when the supply-side damper and the discharge-side damper are constituted by dampers having a structure in which the liquid chamber and the air chamber are partitioned by the elastically deformable damper film, the air chamber and the discharge of the supply-side damper are discharged. The air chambers of the side dampers are communicated with each other via a communication part. Thereby, the damper capacity | capacitance of a supply side damper and a discharge side damper can be enlarged, suppressing size.

  (12) The supply side damper is a damper having a structure in which the liquid chamber and the air chamber are separated via an elastically deformable damper film, and the discharge side damper is an elastically deformable damper film in a part of the liquid chamber A droplet discharge device according to any one of (1) to (11), wherein the droplet discharge device has a structure including:

  According to this aspect, the supply-side damper is constituted by a damper having a structure in which the liquid chamber and the air chamber are separated by the elastically deformable damper film. On the other hand, the discharge-side damper is constituted by a damper having a structure in which a damper film capable of elastic deformation is provided in a part of the liquid chamber. Since a damper with a small damper capacity of the discharge side damper can be used, a damper having a simple configuration can be used.

  According to the present invention, it is possible to effectively suppress the pressure fluctuation of the liquid with a compact configuration.

Schematic configuration diagram of inkjet printer Schematic configuration diagram of droplet discharge device Bottom view of head module 4-4 sectional view of FIG. Sectional drawing which shows schematic structure of supply side damper and discharge side damper Graph showing pressure fluctuation during ink ejection Block diagram showing system configuration of control system of inkjet printer The figure which shows the 1st modification of a head module. The figure which shows the 2nd modification of a head module. The figure which shows the 1st modification of a supply side damper and a discharge side damper Sectional drawing which shows the structure of the damper which can be used as a supply side damper and a discharge side damper Schematic configuration diagram of a droplet discharge device provided with dampers in a common supply channel and a common discharge channel

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  In the following description, a case where the liquid droplet ejection apparatus according to the present invention is applied to an ink jet printer will be described as an example.

<Inkjet printer configuration>
FIG. 1 is a schematic configuration diagram of an inkjet printer. The inkjet printer 1 is a sheet-type line printer that prints a desired image on a sheet of paper in a single pass, and mainly includes a conveyance unit 10 that conveys the sheet P along a certain conveyance path, and a conveyance unit. And a printing unit 20 that prints an image on the paper P conveyed by the ink jet method.

<Transport section>
The transport unit 10 transports the paper P composed of sheets along a certain transport path. The transport unit 10 includes a rotating drum 12, and winds the paper P around the drum 12 to transport the paper P. The drum 12 is driven by a rotation driving means (not shown) and rotates in the direction of arrow A shown in FIG. The drum 12 is provided with a gripper 12A as a means for gripping the leading end of the paper P. Further, the drum 12 is provided with a suction mechanism (not shown) as means for bringing the paper P into close contact with the peripheral surface. A suction mechanism (not shown) brings the paper P into close contact with the peripheral surface of the drum 12 using static electricity or negative pressure.

  The drum 12 is fed with paper P from a paper feeding means (not shown). Further, the printed paper P is delivered from the drum 12 to a paper discharge means (not shown) and discharged.

<Print section>
The printing unit 20 prints an image on the paper P by ejecting fine droplets of ink toward the paper P conveyed by the conveyance unit 10. The print unit 20 includes a droplet discharge device 30. The droplet discharge device 30 includes an inkjet print head 32, and discharges minute droplets of ink from the print head 32.

  FIG. 2 is a schematic configuration diagram of the droplet discharge device.

  As shown in FIG. 2, the droplet discharge device 30 mainly includes a print head 32, an ink supply unit 60 that circulates and supplies ink to the print head 32, and a flow path on the ink supply side with respect to the print head 32. A supply-side damper 80 provided and a discharge-side damper 90 provided in a flow path on the ink discharge side with respect to the print head 32 are provided.

[Print head]
The print head 32 is an example of a droplet discharge head. The print head 32 is composed of a line head having a length corresponding to the width of the paper P. The print head 32 is configured by connecting a plurality of head modules 40. The individual head modules 40 constituting the print head 32 are integrated by being attached to the support frame 34 to constitute one print head 32. Each head module 40 is detachably attached to the support frame 34 independently. When used for single-pass inkjet, the width direction of the paper P is substantially a direction orthogonal to the direction in which the paper P is conveyed.

[Head module]
FIG. 3 is a bottom view of the head module.

  The head module 40 has a nozzle surface 42 on the bottom surface portion. The nozzle surface 42 is a surface on which the nozzle 44 is disposed. The nozzles 44 are arranged in a line at a constant interval on the nozzle surface 42. The direction in which the nozzles 44 are arranged is the direction in which the head modules 40 are joined together.

  4 is a cross-sectional view taken along line 4-4 of FIG.

  As shown in FIG. 4, a pressure chamber 46 is provided for each nozzle 44 inside the head module 40. Each nozzle 44 communicates with a corresponding pressure chamber 46.

  Each pressure chamber 46 includes a piezo element 48 as an actuator for ejecting ink droplets from the nozzle 44. The piezo element 48 deforms a part of the wall surface of the pressure chamber 46, thereby expanding and contracting the volume of the pressure chamber 46 and ejecting ink droplets from the nozzle 44.

  Inside the head module 40, an internal supply channel 50 for supplying ink to each pressure chamber 46 is provided. The internal supply flow channel 50 is an example of a flow channel on the supply side disposed inside the head module 40, and includes an internal common supply flow channel 50A and an internal individual supply flow channel 50B. The internal common supply flow path 50A is a flow path common to the pressure chambers 46, and the internal individual supply flow path 50B is a flow path individually connected to the pressure chambers 46. Each pressure chamber 46 communicates with the internal common supply flow path 50A via the internal individual supply flow path 50B.

  Further, inside the head module 40, an internal discharge channel 52 for discharging ink from each pressure chamber 46 is provided. The internal discharge flow path 52 is an example of a flow path on the discharge side arranged inside the head module, and is configured by an internal common discharge flow path 52A and an internal individual discharge flow path 52B. The internal common discharge flow path 52A is a flow path common to each pressure chamber 46, and the internal individual discharge flow path 52B is a flow path that is individually connected to each pressure chamber 46. Each pressure chamber 46 communicates with the internal common discharge channel 52A via the internal individual discharge channel 52B.

  The head module 40 includes a supply port 54 for supplying ink to the internal common supply flow channel 50A and a discharge port 56 for discharging ink from the internal common discharge flow channel 52A. The ink supplied from the supply port 54 is supplied to each pressure chamber 46 through the internal common supply channel 50A and the internal individual supply channel 50B. The ink in each pressure chamber 46 is discharged from the discharge port 56 through the internal individual discharge flow path 52B and the internal common discharge flow path 52A.

[Ink supply section]
The ink supply unit 60 is an example of a liquid supply unit, and circulates and supplies ink that is a discharge liquid to the print head 32. Since the print head 32 of the present embodiment is configured by connecting a plurality of head modules 40, ink is supplied to each head module 40.

  As shown in FIG. 2, the ink supply unit 60 mainly includes an ink tank 62 for storing ink ejected from the print head 32, and an external supply channel for supplying ink from the ink tank 62 to the print head 32. 64, a supply pump 66 for feeding ink from the ink tank 62 to the print head 32 via the external supply flow path 64, and an external discharge flow for returning the ink discharged from the print head 32 to the ink tank 62. A path 68 and a discharge pump 70 for feeding ink from the print head 32 to the ink tank 62 via the external discharge flow path 68 are configured.

  The ink tank 62 stores ink that is a liquid ejected from the print head 32. The type of ink is not particularly limited.

  The external supply channel 64 includes an external common supply channel 64A, an external individual supply channel 64B, and an external supply manifold 64C.

  The external common supply channel 64 </ b> A is a channel connected to the ink tank 62. The external common supply flow path 64A is formed of, for example, a flexible tube.

  The external individual supply channel 64 </ b> B is an example of a supply-side channel disposed outside the head module 40. The external individual supply channel 64 </ b> B is connected to the supply port 54 of each head module 40 constituting the print head 32. Therefore, the same number of external individual supply channels 64 </ b> B as the head modules 40 constituting the print head 32 are provided. The flow path on the supply side of each head module 40 includes the external individual supply flow path 64 </ b> B and the internal supply flow path 50 inside the head module 40. The external individual supply channel 64B is constituted by a flexible tube, for example.

  The external supply manifold 64C connects the external common supply flow path 64A and each external individual supply flow path 64B. The external supply manifold 64C includes a branching flow path, all of which have the same length.

  The ink flowing through the external common supply flow path 64A is branched through the external supply manifold 64C, flows through each external individual supply flow path 64B, and is supplied to each head module 40.

  In the external supply channel 64, an individual supply valve 72 is provided in each external individual supply channel 64B. The individual supply valve 72 individually opens and closes each external individual supply channel 64B. Accordingly, it is possible to individually control the supply of ink to the plurality of head modules 40.

  The supply pump 66 sends ink from the ink tank 62 to the print head 32 via the external supply flow path 64. The supply pump 66 is constituted by a tube pump, for example, and is provided in the external common supply flow path 64A.

  The external discharge flow path 68 includes an external common discharge flow path 68A, an external individual discharge flow path 68B, and an external discharge manifold 68C.

  The external common discharge channel 68 </ b> A is a channel connected to the ink tank 62. The external common discharge flow path 68A is formed of, for example, a flexible tube.

  The external individual discharge flow path 68B is an example of a flow path on the discharge side arranged outside the head module 40. The external individual discharge channel 68 </ b> B is a channel connected to the discharge port 56 of each head module 40 constituting the print head 32. Accordingly, the same number of external individual discharge channels 68B as the head modules 40 constituting the print head 32 are provided. The discharge-side flow path of each head module 40 includes the external individual discharge flow path 68B and the internal discharge flow path 52 inside the head module 40. The external individual discharge flow path 68B is formed of, for example, a flexible tube.

  The external discharge manifold 68C connects the external common discharge flow path 68A and each external individual discharge flow path 68B. The external discharge manifold 68C includes a branching flow path, all of which are configured the same.

  The ink flowing through each external individual discharge flow path 68B joins via the external discharge manifold 68C, flows through the external common discharge flow path 68A, and is collected in the ink tank 62.

  The external discharge channel 68 is provided with an individual discharge valve 74 in each external individual discharge channel 68B. The individual discharge valve 74 individually opens and closes each external individual discharge flow path 68B. Accordingly, it is possible to individually control the discharge of ink to the plurality of head modules 40.

  The discharge pump 70 sends ink from the print head 32 to the ink tank 62 via the external discharge channel 68. The discharge pump 70 is constituted by a tube pump, for example, and is provided in the external common discharge flow path 68A.

[Supply damper and discharge damper]
The supply-side damper 80 is provided in the supply-side flow path of each head module 40. In the present embodiment, the external individual supply channel 64B is provided. As described above, the external individual supply channel 64B is an example of a supply-side channel disposed outside the head module 40, and connects the supply port 54 of each head module 40 and the external supply manifold 64C. It is.

  The discharge side damper 90 is provided in the flow path on the discharge side of each head module 40. In the present embodiment, the external individual discharge channel 68B is provided. As described above, the external individual discharge flow path 68B is an example of a discharge-side flow path disposed outside the head module 40, and connects the discharge port 56 of each head module 40 and the external discharge manifold 68C. It is.

  FIG. 5 is a cross-sectional view illustrating a schematic configuration of the supply-side damper and the discharge-side damper.

  As shown in FIG. 5, the supply-side damper 80 includes a liquid chamber 82 and an air chamber 84 in a main body 80 </ b> A, and the liquid chamber 82 and the air chamber 84 are partitioned by an elastically deformable damper film 86. It is a damper. The damper film 86 is made of, for example, a resin film. The main body 80A is provided with an ink inlet 88A and an outlet 88B communicating with the liquid chamber 82. The ink flows into the liquid chamber 82 from the inlet 88A, flows through the liquid chamber 82, and flows out from the outlet 88B.

  The discharge-side damper 90 is also a damper having a structure in which a liquid chamber 92 and an air chamber 94 are provided in the main body 90A, and the liquid chamber 92 and the air chamber 94 are partitioned by an elastically deformable damper film 96. The damper film 96 is made of, for example, a resin film. The main body 90 </ b> A includes an ink inlet 98 </ b> A and an outlet 98 </ b> B communicating with the liquid chamber 92. The ink flows into the liquid chamber 92 from the inflow port 98A, flows through the liquid chamber 92, and flows out from the outflow port 98B.

  In the damper having such a structure, the damper capacity is determined mainly by the hardness of the damper film, the area of the damper film, and the volume of the air chamber. Therefore, in the case of a damper film made of the same material, the damper capacity increases as the area of the damper film increases and the volume of the air chamber increases. And it becomes possible to respond | correspond to a big pressure fluctuation, so that a damper capacity | capacitance becomes large.

  On the other hand, the size of the damper increases as the area of the damper film increases and the volume of the air chamber increases.

  In the droplet discharge device 30 of the present embodiment, the discharge side damper 90 is configured with a damper having a smaller damper capacity than the supply side damper 80. This is based on the following reason. That is, when the liquid ejected from the nozzle is circulated and supplied to the print head as in the print head of this embodiment, the ink flow rate on the supply side is equivalent to the amount of ink ejected from the nozzle. Becomes larger than the flow rate of ink on the discharge side. As a result, the influence on the pressure fluctuation is greater on the supply side than on the discharge side. Therefore, in the droplet discharge device 30 of the present embodiment, a damper having a large damper capacity is used for the supply-side damper 80, while a damper having a small damper capacity is used for the discharge-side damper 90, so that the damper can be appropriately installed. It arranges and suppresses pressure fluctuation efficiently.

  As described above, the damper capacity is related to the size of the damper, and the size increases as the damper capacity increases. By using a damper having a small damper capacity for the discharge-side damper 90, a small damper can be used, and the whole can be made compact when mounted on the print head 32. The downsizing makes it possible to arrange the head modules 40 constituting the print head 32 at a high density, and to construct the print head 32 capable of recording a higher quality image.

  The damper capacities of the supply side damper 80 and the discharge side damper 90 are set according to the pressure fluctuation to be suppressed. In the present embodiment, the capacity of the supply side damper 80 is 500 cubic millimeters, and the capacity of the discharge side damper 90 is 300 cubic millimeters smaller than the capacity of the supply side damper 80. As a result, downsizing of the print head 32 is achieved.

  FIG. 6 is a graph showing pressure fluctuations during ink ejection. FIG. 4A shows the pressure fluctuation in the supply-side flow path, and FIG. 4B shows the pressure fluctuation in the discharge-side flow path.

  As the ink is ejected, pressure fluctuations occur in the ink flowing in the flow path. This pressure fluctuation occurs with a vibration, and the vibration attenuates with time.

  The damper capacities of the supply-side damper 80 and the discharge-side damper 90 are set so as to be able to absorb the maximum fluctuation in pressure fluctuation. That is, the damper capacity is set so as to be able to absorb the pressure fluctuation in the shaded portion shown in FIG.

  The pressure fluctuation increases when a high density image is printed, that is, when the discharge amount becomes maximum. Therefore, it is preferable to set the damper capacity according to the pressure fluctuation when the discharge amount becomes maximum.

  As shown in FIGS. 6A and 6B, the pressure fluctuation is larger on the supply side than on the discharge side. For example, when the ratio of the flow rate of the ink flowing through the flow path is 2: 1 between the supply side and the discharge side, the magnitude of the pressure fluctuation is also approximately 2: 1. Therefore, the damper capacity can be set by the ratio of the flow rates. For example, when the flow ratio is 2: 1, the damper capacity of the discharge-side damper 90 can be ½ of the damper capacity of the supply-side damper 80.

  The supply-side damper 80 and the discharge-side damper 90 are preferably set so as to suppress pressure fluctuations to about 100 to 1000 Pa.

  In consideration of suppression of pressure fluctuations associated with ink ejection, the supply-side damper 80 and the discharge-side damper 90 are preferably disposed near the head module 40.

<Control system>
FIG. 7 is a block diagram showing a system configuration of a control system of the ink jet printer.

  The inkjet printer 1 includes a computer 100 that functions as a control unit.

  The computer 100 functions as a conveyance control unit 102, a print control unit 104, and an ink supply control unit 106 by executing a predetermined control program. The conveyance control unit 102 controls the conveyance unit 10 to control conveyance of the paper P. The print control unit 104 controls the print head 32 to control image recording. The ink supply control unit 106 controls the ink supply unit 60 to control the supply of ink to the print head 32.

  Further, the computer 100 functions as an image processing unit by executing a predetermined image processing program. The image processing unit acquires image data of an image to be printed on the paper P, performs necessary image processing on the image data, and generates dot data necessary for printing by the printing unit 20. The print control unit 104 drives the print head 32 based on the generated dot data and prints an image on the paper P.

  The computer 100 also includes a communication unit 110 for communicating with external devices, an operation unit 112 for operating the inkjet printer 1, a display unit 114 for displaying various information, and various data. A storage unit 116 and the like are connected. Image data of an image to be printed by the inkjet printer 1 is taken into the computer 100 via the communication unit 110. In addition, a control program executed by the computer 100 and various data necessary for control are stored in the storage unit 116.

<Operation of inkjet printer>
<Print operation>
The paper P is fed to the drum 12 of the transport unit 10 by a paper feeding means (not shown). The paper P fed to the drum 12 is wound around the peripheral surface of the drum 12 and transported. In the transport process, ink droplets are ejected from the print head 32 and an image is printed on the surface. The paper P on which the image is printed is discharged from the drum 12 through a paper discharge unit.

<Ink supply>
As described above, ink is circulated and supplied. The ink supply control unit 106 controls driving of the supply pump 66 and the discharge pump 70 to circulate ink. The ink supply control unit 106 controls the supply of ink to the print head 32 and the discharge of ink from the print head 32 to circulate the ink. At this time, the ink supply control unit 106 controls supply and discharge of ink to the print head 32 so that a prescribed back pressure is applied.

<Suppression of pressure fluctuation>
When the piezo element 48, which is an actuator, is driven to eject ink from the nozzle 44, pressure fluctuations occur in the ink flowing through the flow path. Such pressure fluctuation adversely affects the meniscus position and degrades the discharge performance.

  The inkjet printer 1 of the present embodiment includes a supply-side damper 80 in the supply-side flow path, and a discharge-side damper 90 in the discharge-side flow path. The supply-side damper 80 and the discharge-side damper 90 are Since each of the head modules 40 constituting the print head 32 is provided, pressure fluctuations accompanying ink ejection can be effectively suppressed.

  In addition, since the ink jet printer 1 of the present embodiment uses dampers having different damper capacities on the supply side and the discharge side in consideration of the effect on pressure fluctuation, The configuration can be made compact. In other words, instead of installing dampers with the same damper capacity on the supply side and discharge side, the dampers with the required damper capacity are installed on each side, so that the size of the damper used can be optimized, and as a result Can be made compact. The downsizing makes it possible to arrange the head modules 40 constituting the print head 32 at a high density, and to construct the print head 32 capable of recording a higher quality image.

《Installation position of supply side damper and discharge side damper》
As described above, it is preferable to dispose the supply-side damper 80 and the discharge-side damper 90 in the vicinity of the head module 40 in consideration of suppression of pressure fluctuation accompanying ink ejection. More preferably, it is arranged at the next position. That is, when the wavelength of the pressure wave transmitted through the ink is λ, the supply-side damper 80 and the discharge-side damper 90 are installed within a distance λ or less from the piezo element 48 that is an actuator. Thereby, the pressure fluctuation accompanying discharge can be suppressed more effectively.

  The wavelength λ of the pressure wave transmitted through the ink is obtained by λ = V / H, where H is the ejection frequency and V is the sound velocity of the ink. For example, when the setting of the ejection frequency H is H = 10 to 75 [kHz] and the sound velocity V of the ink is V = 1500 [m / sec], the wavelength λ of the pressure wave transmitted through the ink is λ = 1500 [m / sec]. sec] / 10 to 75 [kHz] = 20 to 150 [mm]. Accordingly, in this case, by providing the supply-side damper 80 and the discharge-side damper 90 at least within a distance of 20 [mm] or less from the piezo element 48, pressure fluctuations associated with discharge can be more effectively suppressed. This distance is the distance of the flow path from the piezoelectric element 48 to the supply side damper 80 and the discharge side damper 90.

<Modification of head module>
<Modification 1>
FIG. 8 is a diagram illustrating a first modification of the head module.

  As shown in the figure, the head module 40 of this example is a head module having a structure in which a supply side damper 80 and a discharge side damper 90 are integrally provided.

  The supply-side damper 80 has a structure in which the liquid chamber 82 and the air chamber 84 are partitioned by an elastically deformable damper film 86, and is provided integrally with the head module 40. The liquid chamber 82 communicates with the supply port 54 for supplying ink to the head module 40 via the inflow path 89A. The liquid chamber 82 is connected to the internal common supply channel 50A in the head module 40 via the outflow channel 89B. The outflow path 89 </ b> B is formed in the partition wall 40 </ b> A that constitutes a part of the head module 40. The liquid chamber 82 is disposed adjacent to the internal common supply channel 50A via the partition wall 40A.

  The discharge side damper 90 has a structure in which the liquid chamber 92 and the air chamber 94 are partitioned by an elastically deformable damper film 96 and is provided integrally with the head module 40. The liquid chamber 92 is connected to the internal common discharge flow path 52A in the head module 40 via the inflow path 99A. The liquid chamber 92 is communicated with a discharge port 56 for discharging ink from the head module 40 via the outflow path 99B. The inflow channel 99A is formed in the partition wall 40A that constitutes a part of the head module 40. The liquid chamber 92 is disposed adjacent to the internal common discharge channel 52A via the partition wall 40A.

  According to the head module 40 of this example, ink is always supplied to the head module 40 via the supply side damper 80 and discharged from the head module 40 via the discharge side damper 90. Thereby, ink pressure fluctuation can be effectively suppressed.

  Further, according to the head module 40 of the present example, the supply-side damper 80 and the discharge-side damper 90 can be installed in the vicinity of the piezo element 48 that is an actuator, so that pressure fluctuation accompanying ink ejection can be more effectively suppressed.

  Furthermore, since it is not necessary to separately provide a supply-side damper and a discharge-side damper in the external individual supply flow path 64B and the external individual discharge flow path 68B, the configuration can be further downsized and the assembly can be facilitated.

<Modification 2>
FIG. 9 is a diagram illustrating a second modification of the head module.

  As shown in the figure, the head module 40 of this example is provided with a supply-side damper 80 and a discharge-side damper 90 in the flow path inside the head module 40.

  The supply-side damper 80 has a structure in which the liquid chamber 82 and the air chamber 84 are partitioned by an elastically deformable damper film 86, and is provided in the internal individual supply channel 50B. As described above, the internal individual supply channel 50 </ b> B is a part of the internal supply channel 50, and is a part of the supply-side channel disposed inside the head module 40. Since the internal individual supply channel 50B is provided for each nozzle, the supply-side damper 80 is also provided for each nozzle.

  Similarly, the discharge side damper 90 has a structure in which the liquid chamber 92 and the air chamber 94 are partitioned by an elastically deformable damper film 96, and is provided in the internal individual discharge flow path 52B. As described above, the internal individual discharge flow path 52 </ b> B is a part of the internal discharge flow path 52 and is a part of the discharge-side flow path disposed inside the head module 40. Since the internal individual discharge channel 52B is provided for each nozzle, the discharge side damper 90 is also provided for each nozzle.

  According to the head module 40 of this example, the ink is supplied to the pressure chamber 46 via the supply side damper 80 and is discharged from the pressure chamber 46 via the discharge side damper 90. Thereby, ink pressure fluctuation can be effectively suppressed.

  Further, according to the head module 40 of this example, the supply-side damper 80 and the discharge-side damper 90 can be installed in the vicinity of the piezo element 48 that is an actuator, so that it is possible to more effectively suppress pressure fluctuations associated with ink ejection. .

  Furthermore, since it is not necessary to separately provide the supply-side damper and the discharge-side damper in the external individual supply flow path 64B and the external individual discharge flow path 68B, the configuration can be further downsized and the assembly can be facilitated.

  In this example, the supply-side damper 80 and the discharge-side damper 90 are arranged in the internal individual supply flow path 50B and the internal individual discharge flow path 52B, but the internal common supply flow path 50A and the internal common discharge flow path 52A. Alternatively, the supply-side damper 80 and the discharge-side damper 90 may be arranged.

<< Modification of supply side damper and discharge side damper >>
<Modification 1>
FIG. 10 is a diagram illustrating a first modification of the supply-side damper and the discharge-side damper.

  As shown in the figure, the supply-side damper 80 and the discharge-side damper 90 of this example have a structure in which the air chambers communicate with each other. That is, the air chamber 84 of the supply-side damper 80 and the air chamber 94 of the discharge-side damper 90 are communicated with each other via the communication pipe 78 as a communication portion.

  According to the supply-side damper 80 and the discharge-side damper 90 having such a structure, the capacity of each air chamber can be increased, so that a large damper capacity can be secured with a compact configuration. Thereby, further downsizing can be realized.

<Modification 2>
In the above embodiment, a damper having a structure in which a liquid chamber and an air chamber are partitioned by a damper film is used as a supply-side damper and a discharge-side damper, but a damper used as a supply-side damper and a discharge-side damper is However, the present invention is not limited to this.

  FIG. 11 is a cross-sectional view illustrating a configuration of a damper that can be used as a supply-side damper and a discharge-side damper.

  The damper 120 shown in the figure is a damper having a structure in which only the liquid chamber 122 is provided. The main body 120A is provided with only the liquid chamber 122, and a part of the wall surface of the liquid chamber 122 is constituted by a damper film 124 that can be elastically deformed. The damper film 124 is composed of a film body made of a flexible material such as rubber, for example.

  The damper having such a structure has a small damper capacity, but can be made compact. Therefore, it is effective to use as a discharge side damper. That is, a damper having a structure in which a liquid chamber and an air chamber are separated by a damper film is used for the supply side damper, and a part of the liquid chamber 122 is provided for the discharge side damper as in the damper 120 of the present example. A damper composed of the damper film 124 is used. Thereby, the whole structure can be simplified and it can be made compact.

<Modification of print head>
In the above embodiment, the print modules are formed by connecting the head modules in a line on the same straight line, but the form of connecting the head modules is not limited to this. For example, the head modules can be arranged in a zigzag manner and joined together.

  Moreover, in the said embodiment, in order to demonstrate easily, although the form which has arrange | positioned the nozzle to the nozzle surface in a line is shown, the arrangement | sequence of a nozzle is not limited to this. The nozzles can also be arranged in a matrix on the nozzle surface. By arranging the nozzles in a matrix on the nozzle surface, the nozzles can be arranged with higher density.

<Modification of print section>
In the above embodiment, for the sake of simplicity, one print head is shown. However, the number of print heads arranged in the print unit is not limited to this. For example, when printing a color image, four print heads of cyan, magenta, yellow, and black are provided. As the number of print heads arranged in the print unit increases, the demand for compactness increases. Therefore, as the number of print heads arranged in the print unit increases, the present invention works more effectively.

<Modification of ink supply unit>
In the above-described embodiment, the supply pump and the discharge pump are used to circulate the ink. However, the ink may be circulated using the water head difference.

<< Other modifications >>
In the above embodiment, the supply-side damper and the discharge-side damper are installed for each head module, but separately from the supply-side damper and the discharge-side damper installed for each head module, the external common supply flow path and the external common A damper may also be installed in the discharge channel.

  FIG. 12 is a schematic configuration diagram of a droplet discharge device provided with dampers in a common supply channel and a common discharge channel.

  As shown in the figure, a main supply side damper 130 is provided in the external common supply flow path 64A. Further, the main discharge side damper 132 is provided in the external common discharge flow path 68A. The main supply side damper 130 and the main discharge side damper 132 are installed mainly for the purpose of suppressing pulsation of the supply pump 66 and the discharge pump 70, and a damper having a large damper capacity is used.

  Thus, by providing dampers in the common supply flow path and the common discharge flow path, pulsation of the supply pump and the discharge pump can be suppressed, and ink can be supplied more stably.

  In the above embodiment, the case where the present invention is applied to an inkjet printer has been described as an example. However, the application of the present invention is not limited to this. In addition, for example, a color filter manufacturing apparatus for manufacturing a color filter by discharging ink or the like onto a film or glass, or an organic EL display panel (organic electroluminescence solution) by discharging an organic EL solution (organic electroluminescence solution) onto a substrate. The same applies to devices that form luminescence display panels, devices that eject molten solder onto a substrate to form bumps for component mounting, and devices that eject metal-containing liquids to form wiring patterns. it can.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet printer, 10 ... Conveyance part, 12 ... Drum, 12A ... Gripper, 20 ... Print part, 30 ... Droplet discharge apparatus, 32 ... Print head, 34 ... Support frame, 40 ... Head module, 40A ... Septum, 42 ... nozzle face, 44 ... nozzle, 46 ... pressure chamber, 48 ... piezo element, 50 ... internal supply flow path, 50A ... internal common supply flow path, 50B ... internal individual supply flow path, 52 ... internal discharge flow path, 52A ... Internal common discharge channel, 52B ... Internal individual discharge channel, 54 ... Supply port, 56 ... Discharge port, 60 ... Ink supply unit, 62 ... Ink tank, 64 ... External supply channel, 64A ... External common supply channel, 64B ... External individual supply flow path, 64C ... External supply manifold, 66 ... Supply pump, 68 ... External discharge flow path, 68A ... External common discharge flow path, 68B ... External individual discharge flow path, 68C External discharge manifold, 70 ... discharge pump, 72 ... individual supply valve, 74 ... individual discharge valve, 78 ... communication piping, 80 ... supply side damper, 80A ... main body, 82 ... liquid chamber, 84 ... air chamber, 86 ... damper Membrane, 88A ... Inlet, 88B ... Outlet, 89A ... Inlet channel, 89B ... Outlet channel, 90 ... Drain on the discharge side, 90A ... Main body, 92 ... Liquid chamber, 94 ... Air chamber, 96 ... Damper membrane, 98A ... Flow Inlet, 98B ... Outlet, 99A ... Inlet passage, 99B ... Discharge passage, 100 ... Computer, 102 ... Conveyance control unit, 104 ... Print control unit, 106 ... Ink supply control unit, 110 ... Communication unit, 112 ... Operation unit, DESCRIPTION OF SYMBOLS 114 ... Display part, 116 ... Memory | storage part, 120 ... Damper, 120A ... Main body, 122 ... Liquid chamber, 124 ... Damper film | membrane, 130 ... Main supply side damper, 132 ... Main discharge side damper

Claims (12)

A liquid comprising a nozzle and a supply port and a discharge port for the liquid discharged from the nozzle, and a plurality of head modules to which the liquid is circulated and supplied through the supply port and the discharge port. A droplet discharge head;
A liquid supply unit that circulates and supplies the liquid to each of the head modules constituting the droplet discharge head;
A supply-side damper provided in a supply-side flow path of each of the head modules constituting the droplet discharge head;
A discharge-side damper that is provided in a discharge-side flow path of each of the head modules constituting the droplet discharge head, and is configured by a damper having a smaller damper capacity than the supply-side damper;
A droplet discharge device comprising: The supply-side damper is provided in a supply-side flow path disposed outside the head module,
The discharge-side damper is provided in a discharge-side flow path disposed outside the head module.
The droplet discharge device according to claim 1. The supply side damper and the discharge side damper are provided integrally with the head module,
The droplet discharge device according to claim 2. The supply side damper has a damper film at least in part and a liquid chamber communicated with the supply port, and the liquid chamber passes through a partition wall forming a part of the head module. A supply-side flow path disposed adjacent to a supply-side flow path disposed in the interior of the head module, and disposed in the head module via an outflow path formed in the partition; and the liquid chamber Communicated,
The discharge-side damper has a damper film at least in part and a liquid chamber communicated with the discharge port, and the liquid chamber passes through a partition wall forming a part of the head module. A discharge-side flow path disposed adjacent to a discharge-side flow path disposed in the interior of the head module, and disposed in the head module via an inflow path formed in the partition; and the liquid chamber. Communicated,
The droplet discharge device according to claim 3. The supply-side damper is provided in a supply-side flow path disposed inside the head module;
The discharge side damper is provided in a flow path on the discharge side disposed inside the head module.
The droplet discharge device according to claim 1. The supply side damper and the discharge side damper are provided for each nozzle,
The droplet discharge device according to claim 5. The supply-side damper and the discharge-side damper are arranged in the vicinity of an actuator that discharges the liquid from the nozzle.
The droplet discharge device according to claim 5 or 6 . When the wavelength of the pressure wave transmitted through the liquid is λ, the supply-side damper and the discharge-side damper are disposed within a range of λ or less from the actuator.
The liquid droplet ejection apparatus according to claim 7. The ratio of the damper capacity of the supply-side damper and the damper capacity of the discharge-side damper is the same as the ratio of the flow rate of the liquid flowing through the supply-side flow path and the flow rate of the liquid flowing through the discharge-side flow path. ,
The liquid droplet ejection apparatus according to claim 1. The supply-side damper and the discharge-side damper are dampers having a structure in which a liquid chamber and an air chamber are partitioned by a damper film that can be elastically deformed.
The droplet discharge device according to claim 1. The air chamber of the supply-side damper and the air chamber of the discharge-side damper are communicated with each other via a communication portion;
The droplet discharge device according to claim 10. The supply-side damper is a damper having a structure in which a liquid chamber and an air chamber are separated via a damper film that can be elastically deformed,
The discharge side damper is a damper having a structure in which a damper film capable of elastic deformation is provided in a part of the liquid chamber.
The droplet discharge device according to claim 1.

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