JP2008290407A - Droplet discharge apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent fine droplets from adhering to an electric circuit part even if the fine droplets floating without reaching a discharge object are formed at the time when the droplets are discharged. <P>SOLUTION: A discharge head unit 2 comprises a case composed of a box-like head holder 20 and a lid 20a, and a discharge head 3 having a nozzle 7 to discharge droplets and an electric circuit part for driving the discharge head 3 are supported by the case. At least when the droplets are discharged from the nozzle 7, air is supplied to a space in the case from an external pump via a gas supply tube 73, and the space is brought into a state where it has a pressure higher than an external pressure. Thus, even if fine droplets floating in a misty state are formed along with the discharge of the droplets from the nozzle 7, the fine droplets are kept from entering into the case. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a droplet discharge device including a discharge head unit that discharges droplets.

  In a droplet discharge device, for example, a recording device, when performing a recording operation, ink is discharged from a nozzle onto a paper that is a discharge target. In addition to discharging ink droplets that land on a paper, a minute floating in a mist form Ink droplets (ink mist) are known to be generated.

  Such ink mist floats without landing on the paper and adheres to various members inside the apparatus. The space outside the unit composed of the ejection head and the electrical components that drive it is wide, and it is easy to take measures to remove ink mist by utilizing the air flow by a cooling fan or the like. Such a measure is difficult to take in the unit, and since it is close to the ejection head, the ink mist tends to adhere to the electrical components in a short period of time, which may cause an electrical short circuit or corrosion.

In Patent Document 1, an electric circuit board is mounted inside a box-shaped head holder having an open upper surface and covered with a lid. However, an ink mist enters from a gap between the head holder and the lid, and the electric circuit. Since there is a possibility of adhering to the substrate, a frame-shaped shielding member is sandwiched between the peripheral edge on the electric circuit substrate and the lid.
JP 2006-123246 A (refer to FIGS. 2 to 4)

  However, in the structure of Patent Document 1, in order to prevent ink mist from entering the electric circuit on the electric circuit board with certainty, the shielding member must be pressed and held with a strong force so as not to generate a gap. . When a compressible member having elasticity is applied to the shielding member, a compression reaction force is applied to the electric circuit board and the lid, and deformation or the like occurs.

  The present invention solves the above-described problem, and even when a small droplet that floats without landing on the discharge target is generated during the discharge of the droplet, the small droplet adheres to the electric circuit unit. An object of the present invention is to realize a droplet discharge device that can prevent the occurrence of the droplet discharge.

  In order to achieve the above object, a liquid droplet ejection apparatus according to claim 1 includes an ejection head having a nozzle for ejecting liquid droplets, an electric circuit unit for driving the ejection head, and the nozzle. A box-shaped housing that is exposed to the outside to support the discharge head and accommodates the electric circuit portion therein, and at least when the liquid droplets are discharged from the nozzle, the internal pressure of the housing is external pressure And a pressurizing means for bringing the state into a higher state.

  According to a second aspect of the present invention, in the droplet discharge device according to the first aspect, the pressurizing means supplies gas into the casing and is installed at a position away from the casing. And is connected to the casing through a pipe line.

  According to a third aspect of the present invention, in the droplet discharge device according to the first or second aspect, the pressurizing means supplies gas into the casing, and the casing is supplied. In addition, a gap for leaking the gas to the outside is provided.

  According to a fourth aspect of the present invention, in the droplet discharge device according to the second aspect, the casing is provided so as to be movable along the discharge target, and the pressurizing means At least a part of the conduit that is supported by a movable device body and connects the casing and the pressurizing means is formed of a flexible tube. .

  According to a fifth aspect of the present invention, in the liquid droplet ejection apparatus according to the fourth aspect, a cartridge containing the liquid droplets to be supplied to the ejection head is supported by the apparatus body, and the ejection head and the The cartridge is connected by a flexible liquid supply tube, and the tube constituting the conduit and the liquid supply tube are arranged substantially in parallel.

  The invention according to claim 6 is the liquid droplet ejection apparatus according to claim 5, wherein the tube constituting the conduit contains the liquid supply tube therein. It is.

  According to the first aspect of the present invention, the casing supports the ejection head so that the nozzles of the ejection head are exposed to the outside, and the electric circuit portion is accommodated inside the casing. And a pressurizing means makes the pressure inside a housing | casing higher than an external pressure at least, when discharging a droplet from a nozzle. When discharging droplets from the nozzle, in addition to the droplets that land on the discharge target, a minute droplet that floats without landing on the discharge target is generated, but because the internal pressure of the housing is high, The minute droplets can be prevented from entering the inside of the housing. Since the minute liquid droplets do not enter the inside of the housing, it can be prevented from adhering to the electric circuit portion accommodated in the housing and causing an electrical short circuit or corrosion.

  According to invention of Claim 2, the pressurizing means is arrange | positioned in the position away from the housing | casing, in other words, the pressurizing means is separated from the place where the said micro droplet generate | occur | produces. . Therefore, even if the pressurizing means uses the surrounding air to send the gas into the housing, it is unlikely that the above-described minute floating droplets will be taken into the air. As a result, the minute droplets are pressurized. It is possible to avoid being sent into the housing by the means.

  According to invention of Claim 3, the gas supplied to the housing | casing by the pressurization means leaks outside from the clearance gap of a housing | casing. Therefore, since the minute droplets floating as the droplets are ejected can be moved by the leaked gas, contamination due to the adhesion of minute droplets around the ejection head in the apparatus can be reduced.

  According to the fourth aspect of the present invention, at least a part of the conduit connecting the casing movable with respect to the apparatus main body and the pressurizing means is formed of a flexible tube. Therefore, since the tube bends along with the movement of the casing, there is no concern that the gas flow in the pipe will be hindered even if the casing moves.

  According to the fifth aspect of the present invention, the liquid supply tube that connects the cartridge that stores the liquid to be supplied to the discharge head and the discharge head, and the tube that constitutes the conduit are arranged substantially in parallel. That is, the tubes constituting the pipe line can be arranged along the liquid supply tube, and these can be bundled, so that a large number of tubes can be arranged in an orderly manner in the apparatus.

  According to the invention described in claim 6, since the tube constituting the pipe accommodates the liquid supply tube therein, the tube constituting the pipe and the liquid supply tube can be integrally arranged, and the wiring Space can be reduced.

  A basic embodiment of the present invention will be described below. FIG. 1 is a schematic plan view of a recording apparatus 1 as a droplet discharge apparatus of the present invention. The recording apparatus 1 may be applied to a single printer apparatus, or may be applied to a printer function (recording unit) of a multi-function apparatus having a plurality of functions such as a facsimile function and a copy function.

  As shown in FIG. 1, the recording apparatus 1 includes an ejection head unit 2 that constitutes a carriage. In the ejection head unit 2, the ejection head 3 exposes its nozzles 7 to the lower surface of the ejection head unit 2. It is installed. The first guide member 5 and the second guide member 6 are members that support the ejection head unit 2 that is a carriage so as to be movable in the main scanning direction (Y-axis direction). The discharge head unit 2 reciprocates along the Y-axis direction by a timing belt 11 stretched between a drive pulley 9 connected to a carriage motor 8 and a driven pulley 10.

  A sheet, which is a recording medium (corresponding to a discharge object in claims), is conveyed below the discharge head unit 2 in a sub-scanning direction (X-axis direction) orthogonal to the main scanning direction (Y-axis direction).

  In the apparatus main body 12, a replaceable ink cartridge 13 is stationary. Here, four ink cartridges for black ink, cyan ink, magenta ink, and yellow ink are used according to the number of ink colors. 13 is provided. The ink in each ink cartridge 13 is independently supplied to the ejection head unit 2 via a supply pipe. Here, a flexible resin ink supply tube (corresponding to the liquid supply tube in the claims) 15 is used as the supply tube.

  As shown in FIG. 1, in the apparatus main body 12 of the recording apparatus 1, a maintenance unit 17 is provided on one side (right side in FIG. 1) outside the width (recording area) of the paper in the Y-axis direction. ing. The maintenance unit 17 is provided corresponding to the standby position (home position) of the carriage 2 and performs a recovery operation (purging) for recovering the discharge function of the discharge head 3.

  As shown in FIG. 1, the maintenance unit 17 is provided with a cap body 19. The cap body 19 is provided so as to be displaceable between a position contacting the opening surface of the nozzle 7 and a position separating from the position along the direction (vertical direction) perpendicular to the moving direction of the carriage 2 by lifting means (not shown). It has been.

  The cap body 19 is formed of a rubber-like elastic material. The cap body 19 is formed with a rib 19a that protrudes toward the opening surface of the nozzle 7 so as to surround the outer periphery of the nozzle group when contacting the opening surface. The cap body is formed by elastic deformation of the rib 19a. 19 is in close contact with the opening surface. A discharge port 70 is formed at the bottom of the cap body 19, and the discharge port 70 is connected to a suction pump (not shown) disposed below the cap body 19 with a tube.

  In the recovery operation, the cap body 19 comes into close contact with the opening surface of the nozzle 7, and the ink is forcibly discharged from the nozzle 7 of the ejection head 3 to the inside of the cap body 19 by a suction force (not shown). The waste liquid tank 71 is discharged from the discharge port 70 and stored in the apparatus main body 12 so as to be stored.

  A pressurizing pump 18 (corresponding to the pressurizing means in the claims) is disposed at a position away from the discharge head unit 2 and next to the waste liquid tank 71. The pipe line 72 connected to the pump 18 is configured to send gas, for example, air, to the discharge head unit 2, and the pressure inside the discharge head unit 2 is increased from the outside by the sent gas.

  Of the pipe 72, at least a portion connecting the pump 18 and the discharge head unit 2 is configured by a flexible resinous gas supply tube 73 (corresponding to a tube constituting the pipe in the claims) 73. ing. The above-mentioned portion of the gas supply tube 73 is overlapped in parallel with the ink supply tube 15 as shown in FIG. 1B at least at a portion that is bent as the discharge head unit 2 travels, and is bonded to each other or a band member. (Not shown) or the like. As a result, a large number of tubes can be arranged in an orderly manner inside the apparatus main body 12.

  As a modification of the configuration of the tube, as shown in FIG. 1C, a plurality of ink supply tubes 15 are accommodated in the gas supply tube 73 so that gas, for example, air flows around the ink supply tube 15. You may comprise.

  As shown in FIG. 2, the discharge head unit 2 includes a substantially box-shaped head holder 20 having an open upper surface, and a lid 20 a (see FIG. 3) that covers the upper surface of the head holder 20. The lid body 20a constitutes a casing of the claims, and a space 50 surrounded by a side wall 77 is formed between the bottom plate 21 of the head holder 20 and the lid body 20a. There is a gap between the head holder 20 and the lid 20a to such an extent that gas can leak from the space 50. The ejection head 3 is fixed to the lower surface side of the bottom plate 21 with a reinforcing frame 24 interposed. On the lower surface of the head holder 20, a rib 20 b that protrudes toward the recording medium (lower side) is provided so as to surround the ejection head 3. In other words, the ejection head 3 is disposed inside a recess formed on the lower surface side of the bottom plate 21.

  In order to relieve a step (unevenness) on the lower surface (surface facing the recording medium) side of the head holder 20, a front frame 28 is provided so as to surround the ejection head 3 inside the rib 20b, and the front frame 28 is reinforced. It is attached to the lower surface of the frame 24. Between the outer periphery of the front frame 28 and the outer periphery of the ejection head 3 and the lower edge portion 20a of the head holder 20, a gap 29 is formed over the entire periphery.

  On the upper surface side of the bottom plate 21 of the head holder 20, an ink storage unit 22 that temporarily stores the ink supplied from the ink cartridge 13 and a circuit board 23 are mounted. The circuit board 23 receives a drive signal from a control device (not shown) stationary on the apparatus body 12 via a flexible wiring cable (not shown), and passes through a flexible wiring material 33 connected to the connector 23a. Thus, a drive signal is supplied to the actuator 32 of the ejection head 3. On the circuit board 23, electrical components 23b such as chip resistors and capacitors are also mounted.

  An opening 21a is formed through the bottom plate 21 of the head holder 20. Inside the opening 21a, an ink outlet 22a of the ink reservoir 22 and an ink inlet 31a of the ejection head 3 are provided as a reinforcing frame. Ink is supplied independently from the ink reservoir 22 to the ejection head 3 for each color.

  A slit hole 25 through which the flexible wiring member 33 is inserted is formed in the bottom plate 21 at a position near the one side wall 77a of the head holder 20. Further, the bottom plate 21 has a through hole 27 for pouring the adhesive 26 for fixing the ejection head 3 on the lower surface side thereof along both the one side wall 77a and the other side wall 77b opposite to the side wall 77a. A plurality of each is drilled. The bottom plate 21 is provided with two pins 21b for positioning and fixing a radiator 41, which will be described later.

  Further, a plurality of communication ports 51 are formed in the bottom plate 21 in areas outside the through holes 27 and between the through holes 27 and the side walls 77a and 77b. The communication port 51 communicates the space 50 above the bottom plate 21 with the inside of the recess inside the rib 20b. A connection port 52 is formed in one side wall 77a, and a gas supply tube 73 is connected to the outside of the connection port 52 via a connector. That is, gas is sent from the pump 18 to the space 50 in the head holder 20 through the gas supply tube 73 so that the pressure inside the space 50 becomes higher than the outside.

  The discharge head 3 is similar to the known one described in Japanese Patent Laid-Open No. 2005-322850, and as shown in FIG. 4, a cavity portion 31 having a nozzle 7 opened on the lower surface side and a pressure chamber 35 on the upper surface side. The plate-type actuator 32 and the flexible wiring member 33 are laminated.

  The cavity portion 31 is formed by laminating a plurality of thin plates, and the ink introduced from the ink storage portion 22 to the ink intake port 31a of the cavity portion 31 is distributed to a large number of pressure chambers 35 in the cavity portion 31. An ink supply path 34 is configured.

  As shown in FIG. 4, the actuator 32 includes a plurality of ceramic layers 36 that are flat in a size extending over all the pressure chambers 35 and are stacked in a direction perpendicular to the flat direction, and the plurality of ceramic layers 36. It is comprised from the some electrode arrange | positioned between.

  The electrodes include individual electrodes 37 formed for each pressure chamber 35 and common electrodes 38 formed across the plurality of pressure chambers 35, and are alternately arranged between the ceramic layers 36. The individual electrodes 37 in the stacking direction are integrally connected to each other and led to the surface, and the common electrodes 38 in the stacking direction are also connected to each other and led to the surface. It is connected.

  In the actuator 32 thus provided with electrodes, as is well known, by applying a voltage between the individual electrode 37 and the common electrode 38, the portion of the ceramic layer 36 sandwiched between both electrodes expands and corresponds. Pressure can be applied to the ink in the pressure chamber 35 to eject the ink from the nozzle 7.

  A circuit element 39 for driving the actuator 32 is mounted in the middle of the flexible wiring member 33. The circuit element 39 converts the drive signal serially transmitted from the circuit board 23 into a parallel signal corresponding to a large number of individual electrodes 37 and outputs it as a voltage suitable for driving the ceramic layer 36. Therefore, at the time of recording, the circuit element 39 generates heat by outputting a drive signal so that ink is ejected from a large number of nozzles at a high frequency.

  In order to dissipate the heat of the circuit element 39, the heat dissipating body 41 is fixed to the upper surface side of the bottom plate 21 with pins 21b. The flexible wiring member 33 is routed so that the circuit element 39 is positioned between the bottom plate 21 and the heat radiating body 41, and a rubber-like elastic member is provided at a position facing the heat radiating body 41 and the circuit element 39. 40 is arranged. Thus, the circuit element 39 is brought into close contact with the heat radiating body 41 by the elastic force of the elastic member 40 so as to be able to conduct heat.

  The radiator 41 has a bottom 42 that is substantially parallel to the bottom plate 21 and in close contact with the circuit element 39, and a side 43 that is substantially parallel to the side wall 77 a of the head holder 20 and guides the flexible wiring member 33 to the circuit board 23. It is a metal member formed so as to form an L shape. The bottom portion 42 and the side portion 43 of the radiator 41 are formed long in the same direction as the longitudinal direction (X-axis direction) of the circuit element 39. Two mounting holes 41a are drilled in the bottom portion 42, and the heat radiating body 41 is fixed to the head holder 20 by inserting pins 21b standing on the bottom plate 21 through the mounting holes 41a and performing welding or the like. Is done.

  According to the above configuration, when air is sent to the space 50 of the ejection head unit 2 by the pump 18 during the recording operation, the internal pressure of the space 50 increases, and the clearance 29 from the communication port 51 of the bottom plate 21 or the head holder 20 and the lid Air leaks to the outside through the gap between the discharge head unit 2 and all the gaps opened to the outside of the discharge head unit 2. When the ejection head 3 performs a recording operation, a minute ink mist floating in a mist is generated along with the droplets that land on the paper. This ink mist is generated even if there is a gap in the ejection head unit 2. Since the internal pressure is high, the discharge head unit 2 does not enter. Therefore, the ink mist does not adhere to the electric circuit portions such as the circuit board 23 and the circuit element 39 accommodated in the head holder 20, and as a result, there is no inconvenience that the electric circuit portion is electrically short-circuited or corroded. .

  In addition, air is actively leaked from the gap 29 around the nozzle 7 to generate an air flow around the discharge head in the apparatus, that is, the platen portion that supports the paper and the paper transport unit, and ink mist adheres to them. Can be prevented.

  Furthermore, in the space 50 in the ejection head unit 2, an air flow is generated from the connection port 52 to the outside. Therefore, the heat radiating body 41 is cooled by this air flow, and the heat of the circuit element 39 is also efficiently radiated. Of course, when there is another heat generating part such as the discharge head itself generating heat, the heat is radiated and cooled by the air flow.

  The pump 18 is started at least when the ejection head ejects ink, that is, when a drive signal is supplied, and is controlled so as to be continuously driven while the drive signal exists. Furthermore, the pump may be driven while adding a predetermined time before and after the drive signal exists or while the power of the recording apparatus is turned on.

  In the above-described embodiment, air is used as the gas for increasing the internal pressure in the ejection head unit 2, but other gases can also be used. Although the recording apparatus has been described as an example, it is needless to say that the present invention can be applied to a liquid droplet ejection apparatus that ejects a liquid other than ink, for example, a color liquid for coloring a color filter of a liquid crystal display device.

(A) is a schematic plan view of a recording apparatus as a droplet discharge apparatus of the present invention, (b) is a cross-sectional view taken along line Ib-Ib of (a), and (c) is a modification of (b). FIG. 3 is an exploded perspective view of a discharge head unit of the recording apparatus. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording device 2 Discharge head unit 3 Discharge head 7 Nozzle 13 Ink cartridge 15 Ink supply tube 18 Pump 19 Cap body 20 Head holder 20a Cover body 23 Circuit board 29 Crevice 33 Flexible wiring material 39 Circuit element 41 Radiator 50 Space 51 Exhaust port 72 Pipe 73 Gas supply tube

Claims (6)

An ejection head having a nozzle for ejecting droplets;
An electric circuit unit for driving the ejection head;
A box-like housing that exposes the nozzle to support the discharge head and accommodates the electric circuit portion therein;
At least when a droplet is ejected from the nozzle, the droplet ejecting device includes a pressurizing unit that makes the internal pressure of the casing higher than the external pressure.   2. The pressurizing means supplies gas into the head holder, is installed at a position away from the casing, and is connected to the casing via a pipe line. The droplet discharge device according to 1.   The said pressurization means supplies gas in the said housing | casing, The said housing | casing has the clearance gap which leaks the supplied said gas outside, The Claim 1 or 2 characterized by the above-mentioned. The liquid droplet ejection apparatus described. The casing is provided so as to be movable along the discharge target, and the pressurizing means is supported by an apparatus main body that supports the casing in a movable manner,
The droplet discharge device according to claim 2, wherein at least a part of the conduit connecting the casing and the pressurizing unit is configured by a flexible tube. A cartridge containing the liquid to be supplied to the discharge head is supported by the apparatus main body, and the discharge head and the cartridge are connected by a flexible liquid supply tube.
The droplet discharge device according to claim 4, wherein the tube constituting the conduit and the liquid supply tube are arranged substantially in parallel.   The droplet discharge device according to claim 5, wherein the tube constituting the pipe line accommodates the liquid supply tube therein.

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