JPS63165147A - Fluid applicator head and operating method thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to fluid applicator heads, and more particularly to drop-on-demand jet printing head assemblies incorporating means for ejecting ink or other fluids from nozzle orifices. and a method for operating such a head.

[Conventional technology and problems]

In drop-on-demand jet type fluid applicators, ink, adhesive, or other fluid is ejected from an array of nozzles fixed to a printhead. Fluid flow through the nozzle can be effected by generating pulses of pressure in the fluid immediately upstream of the nozzle orifice, for example when causing a deflection in the printhead wall under the action of an electrostrictive crystal. Alternatively, fluid flow can be controlled by actuating a valve, such as a solenoid valve located in the fluid line between the pressure reservoir and the nozzle of the printhead. The pattern created by the droplets deposited on the material moving across the nozzle is determined by the continuous motion with which the nozzle or valve is actuated. For convenience, such applicator heads are referred to herein as drop-on-demand printer heads.

However, fluids often include compositions that include solvents or other carriers that are prone to evaporation, or, in the case of adhesives, components that tend to dry out or separate over time. As a result, solids tend to separate from the fluid and block the nozzle orifice and passageway for the nozzle. This results in the problem that the action of the applicator head is interrupted for a long time.

In order to eliminate the problems caused by drying of the fluid in the nozzle orifice, it is proposed to equip the applicator head with a pad or other means that is used as a cap to cover the nozzle orifice when the applicator head is not in use. ing. however,
The pad often sticks to the face of the applicator head and
Such devices cannot overcome the problem of solids depositing in the fluid over long periods of time.

Clean the part of the applicator head immediately upstream of the nozzle with a positive flow when the action of the applicator head is interrupted for a long time, for example for about 8 hours, such as at the end of the day or the end of a week. It is proposed to do so. This forward flushing is to remove residual fluid from the applicator head to reduce the build-up of deposits in the nozzle, refrigeration, and passageway leading to the nozzle orifice. The cleaning fluid can be applied over the entire applicator head, but this creates the problem of diluting the fluid that is subsequently applied to the applicator head. It is therefore proposed to supply the cleaning fluid to the applicator head through a side wall of the passage supplying the fluid to the nozzle orifice, for example through a branch feed tube connected substantially at right angles to a chamber provided immediately upstream of the nozzle orifice. has been done.

In previous proposals for cleaning the applicator head with fluid, the applicator head was kept stationary and cleaning fluid was supplied thereto by suitable ducts. However, in this manner, means are used to collect the cleaning fluid as it exits the applicator head so that it does not contaminate objects to which ink or other fluids are to be applied in subsequent operations. This is necessary and the cleaning fluid collection means must not interfere with the application of ink or other fluid to the object when operation of the applicator head is resumed.

Additionally, positive current cleaning is not always able to conveniently remove more sticky deposits from the ablator head. Furthermore, it has been found that if there is a duct for cleaning fluid in the applicator head, droplet formation at the nozzle orifice is adversely affected during operation of the applicator head.

The present invention seeks to provide a rad assembly for an applicator that can solve the above problems.

[Means for solving problems]

Accordingly, the present invention provides a fluid application multi-head in which fluid is ejected from a plurality of nozzles, in particular by pressure pulses or valve means controlling the flow of fluid through the nozzle orifice. The applicator head is cleaned by passing a cleaning fluid through a nozzle orifice and has a first actuation position 1 in which the fluid applicator head is capable of applying droplets of fluid to an object disposed opposite the nozzle orifice. from the nozzle orifice to a second cleaning position in which the nozzle orifice engages a cleaning member incorporating a fluid communication passageway such that cleaning fluid is caused to flow through the nozzle orifice or the passageway associated therewith. It is characterized by the fact that it is possible to do so.

Preferably, the second cleaning station 1 comprises a member on which the region of the applicator head adjacent the nozzle orifice is seated;
Through this member, cleaning fluid is forced to flow in one or both directions through the nozzle orifice. In a particularly preferred configuration, the applicator head of the present invention comprises a surface suitable for receiving cleaning fluid from the nozzle orifice and/or from a cleaning fluid source in sealing engagement with the nozzle exit face of the applicator head. The washing member is adapted to be reciprocated and/or pivoted for relative movement with a cleaning member having a receiving passageway.

The present invention also provides a method of operating an applicator head according to the invention, which method comprises: when it is desired to clean the applicator head and when flowing a cleaning fluid through a nozzle orifice; The applicator head is characterized by moving the applicator head from a first position to a second position.

As mentioned above, the presence of cleaning fluid ducts within the applicator head adversely affects the formation of fluid droplets at the nozzle orifice. Surprisingly, we have found that the problem of droplet formation is reduced if the cleaning fluid is supplied from an orifice in a duct that intersects and traverses the passage supplying the fluid to the nozzle orifice.

Accordingly, from a further point of view, the present invention provides a first fluid passage for directing fluid to a nozzle orifice located at the end of the fluid communication passage, and a second fluid passage that intersects the first fluid passage.
an applicator head having a fluid passageway, the second fluid passageway having a hole for allowing fluid to flow from the second fluid passageway into the first fluid passageway; Placed inside the fluid passage! and directed substantially along an intended flow line of fluid through the first fluid passageway.

Preferably, the second fluid passageway is provided as a substantially cylindrical tube passing diametrically through the first fluid passageway, with the hole for the second fluid passageway extending substantially through the first fluid passageway. Located on the longitudinal axis.

such that the second fluid passageway has a planar area perpendicular to the fluid flow line through the first fluid passageway, which is between 40 and 95 percent of the cross-sectional area of the first fluid passageway at that point. It is particularly preferable to More preferably, the second fluid passage provides a rounded surface for fluid flow through the first fluid passage.

An applicator head according to the present invention provides an electric current which acts directly on the ink or acts on a visible or deformable wall of a chamber communicating with a nozzle orifice to generate pressure pulses in the fluid to eject droplets from the nozzle orifice. It can be applied to a wide range of drop-on-demand type applicators, including those in which fluid is ejected from a nozzle by the action of a transducer such as a strained crystal. However, the present invention provides an applicator of the drop-on-demand type in which the flow of fluid into the nozzle orifice type is controlled by the action of valve means, in particular a solenoid valve placed in the pressure fluid line to the nozzle orifice. Particularly suitable for use. For convenience, the invention will hereinafter be described with respect to such an applicator head.

The fluid flowing through the applicator head may include visible ink compositions based on organic solvents or water, compositions based on thermoplastic carrier media such as meltable waxes or resins, and other fluids such as ultraviolet (UV) fluorescent The composition can be selected from compositions including an indicating medium such as a material. The invention is also applicable to water- or organic solvent-based adhesive compositions, especially polyvinyl acetate polymers and copolymers. For convenience, the present invention will hereinafter be described using water-soluble adhesive compositions containing polyvinyl acetate resins, particularly those that dry quickly or tend to stick over time.

In the present invention, the applicator head has a passage through which adhesive is supplied to the nozzle head. Typically, the passageway is a bore in a solid block, such as aluminum, brass, or stainless steel. However, the invention is also applicable to structures in which the passageway is provided as a tube, for example a stainless steel tube connecting the valve mechanism to the nozzle. If the passage is a bore in a solid block, the bore may be such that it connects directly to the nozzle orifice a valve chamber provided with a valve mechanism for opening and closing the outlet to the chamber acting on the bore. can. However, the particular features of the block design for a given application may require that the bore be of a tortuous course and/or contain one or more chambers. For convenience, the invention will hereinafter be described using a bore that supplies fluid directly from the bamabu mechanism or valve chamber to the nozzle outlet.

The bore forming the passage connecting the valve to the nozzle outlet is
Preferably, it is a simple circular cross-section bore formed in the applicator head by drilling or other methods.

If desired, the passageway walls can be surface coated with a material that is not easily wetted by fluids to reduce the risk of material sticking. Alternatively, the applicator head block may be partially or wholly formed of a material such as polytetrafluoroethylene.

As mentioned above, the valve mechanism preferably comprises a solenoid valve mechanism. It is located entirely within the applicator head and can utilize the bores within the applicator head to provide some of the bores required for proper operation of the valve mechanism. However, for ease of service and replacement, the valve mechanism is preferably removable as a unit from the applicator head. Accordingly, the applicator head typically has a valve chamber with means for receiving in sealing engagement a valve mechanism, a fluid supply bore for supplying fluid to an inlet of the valve mechanism, and an outlet from the valve mechanism. is connected to the passage for the nozzle orifice. Typically, fluid delivery involves the use of a manifold to distribute fluid to multiple valve mechanisms, each serving a single nozzle orifice or set of nozzle orifices. Accordingly, in a preferred construction, the applicator head includes a fluid supply bore that connects each of the valve mechanisms and acts as a manifold. Such a bore typically runs longitudinally along the applicator head block, with a passageway feeding the nozzle orifice running laterally from the valve chamber. The longitudinal bore has a connection to each of the chambers in which the valve is located.

In a particularly preferred construction, the applicator head is made as a long block of metal with a longitudinal bore that acts as a fluid inlet and manifold. This bore intersects a plurality, typically 5 to 16, of transverse bores, each transverse bore having a deep section for seating a solenoid valve, with the inlet boat of the solenoid valve being exposed at the depth of the bore. It is designed to receive fluid from the The outlet ports of the solenoid valves are in sealing engagement with the lateral passages leading to the applicator head block, one serving each nozzle orifice by a given solenoid valve. The longitudinal bore is connected by visible piping or other suitable means to a source of fluid adhesive under pressure.

The applicator head is provided with means for delivering the liquid to be dispensed into a bore which acts as a nozzle orifice. The dispensing liquid may be forced to flow through the entire adhesive flow path through the applicator head. However, it is preferred that the discharge liquid flows only through the flow path area adjacent to the nozzle orifice, such as, for example, the valve chamber, the nozzle orifice and the conduit connecting them. Preferably, the dispensing liquid is delivered from an external source through holes in the applicator head block to a bore connecting the valve chamber or stem with the nozzle orifice. Dispensing liquid is conveniently delivered from a pressurized source via a visible pipe or the like capable of absorbing movement of the head at an interlace between the active and dispensing positions of the head. If desired, the head can be coupled to a dispensing location so that dispensing liquid can be circulated through the head and the dispensing means.

As mentioned above, it is preferred to deliver the discharge liquid via a conduit that intersects the transverse conduit feeding the nozzle orifice. These conduits may be holes in the head block that feed the insertion tubes that intersect the transverse conduits. The insertion tube has an opening for feeding the discharge liquid axially into the transverse conduit. The holes may be fed from a manifold for supplying viscous fluid to the conduit. However, it is preferred that the discharge liquid stream be routed via a single longitudinal tube that intersects each transverse conduit and connects all the conduits.

A conduit or insertion tube for the discharge liquid passes transversely through the conduit connecting the valve chamber and the nozzle orifice. The discharge conduit or insertion tube preferably presents a rounded top surface and a generally semi-circular cross-section for the flow of liquid through the intersecting conduits. The lower or downstream surface of the discharge flow conduit or pipe may be of the same shape as the pipe may have a generally circular cross-section or may be tapered or streamlined, or the pipe may have an inverted droplet-shaped cross-section. It can have the same shape as the case where it is.

The outlet of the discharge liquid from the conduit or tube is located on the downstream wall of the tube, and the discharge liquid flowing from the tube is directed along the same streamline as the viscous material passing through the conduit. Generally, the outlet is generally concentric with the conduit and has a circular orifice.

Thus, in a preferred form of the applicator head, the dispensing fluid is delivered by a tube extending longitudinally along the applicator head and generally parallel to the apertures that deliver the sticky substance. A discharge fluid tube intersects each of the transverse conduits connecting the valve chamber and the nozzle orifice and extends diametrically across the conduits. The tube has a circular exit orifice oriented along the axis of the conduit.

- The tube is of suitable dimensions to allow the discharge liquid stream to be delivered into the conduit. Similarly, the outlet is sized to suit the required flow rate. It will be appreciated that the diameter and outlet dimensions of the tube can be varied along the length of the tube to compensate for the pressure drop along the tube. However, the tube is approximately proportional to the cross-sectional area of the transverse conduit, typically 50 to 9
0%, especially about 75 to 90%, and the liquid
It has been found that there is no adverse effect on the formation of droplets in the nozzle orifice, which are fed under a pressure of 97 kg/am2) to the nozzle orifice. The outlet for the ejected liquid has a diameter of 15 to 90% of the diameter of the tube, and the appropriate diameter can be easily determined by simple trial and error testing.

Delivery of the dispensing liquid through the second liquid streamline is preferably controlled by valve means for each transverse conduit and the adhesive conduits it intersects. In this way, the conduit does not come into contact with the large volume of liquid in the discharge fluid flow line which operates in response to the pressure cavus within the sticky conduit. If one longitudinal tube is used as a discharge liquid delivery line, the transverse conduits are connected to each other by this tube and pressure fluctuations in one adhesive conduit (e.g. when a valve opens or closes it) It would be possible that the phlegm (when the phthalate is used) is transmitted from one adhesive conduit to another. It is therefore preferable to provide valves or other means to isolate the adhesive conduits from each other.

Thus, it is usually preferred to provide valve means in the second flow line intersecting each side of each adhesive conduit.

The valves used to control the flow of fluid to the adhesive conduits and to isolate the adhesive conduits from each other may be selected from a wide variety of types. However, the preferred valve type is a sliding sleeve or plug type valve that can be actuated pneumatically under the control of a central control system, such as a microcomputer, which regulates the actuation of the applicator head in a manner well known in the art. be. However, it is also within the scope of the invention for the valve to be actuated by a push button or the like protruding from one side of the print head, such that the valve is automatically actuated when the applicator head is in the dispensing position. It is.

As mentioned above, the applicator head is moved from an operative position to a position where a liquid stick is to be delivered across a substrate (which may be a paper sheet, plastic sheet, or the like) through a nozzle to its dispensing position. . The movement of the applicator head may be linear, such as when it is moved from one position to another laterally. However, if the movement has both horizontal and vertical components, the lower surface of the applicator head carrying the nozzle orifice will seat downwardly on top of the bottom in the dispensing position, and the contact between the applicator head and the seat will occur. It is preferable to ensure sealing engagement. Movement of the applicator head can thus be achieved by mounting the head on an eccentric shaft that can lift or move the head laterally as required by rotation. Other means of moving the head can be readily devised using known techniques.

If desired, multiple applicator heads according to the invention can be operated in conjunction with each other using conventional mounting, mounting and moving mechanisms.

In the dispensing position, the conduit leading to the nozzle and the nozzle itself are cleaned by flowing liquid through part or all of the sticky channel in the head to remove any sticky material remaining therein. This is accomplished simply by delivering the dispensing liquid to the applicator head and ejecting the dispensing liquid into a trough, channel, or the like on the top of the member at the dispensing position. However, it is preferred that the base of the applicator head form the dispensing position as a cooperating generally flat seat member and move the nozzle orifice into the register position, preferably sealing the aperture in the top surface of the seat. The apertures communicate with a source of dispensing liquid, or with holes through which the dispensing liquid is dispensed or circulated, either directly or through a filter or other treatment material. If necessary, the seat member can have other conduits, such as conduits for supplying compressed air or other fluids and for removing the dispensing liquid at the end of the dispensing process, and pumps for supplying or circulating the dispensing liquid. or other means.

The applicator head preferably engages the dispensing position in sealing engagement to allow recirculation of the dispensing fluid and cleaning from behind. In this way, the upper surface of the member may be formed with a suitable resilient surface and the recess may be provided with a sealing ring or the like.

The act of seating the applicator head in the dispensing position may also be used to actuate a valve that controls the flow of dispensing liquid through the applicator head. For example, pressing a protruding button activates a valve at the second flow end.

The dispensing liquid flows into the conduits and disgorges any residual sticky material in the conduits and nozzles, ensuring that no deposits build up in the conduits or nozzles, no matter how long the printhead is out of operation. The dispensing liquid can be selected from a wide variety of liquids, but a water-cleaning agent mixture commonly used in dispensing similar devices is preferred.

The applicator head of the present invention can incorporate other features used in jet print heads to enhance its operation. Thus, the applicator head may be provided with heating means through which the thermoplastic ink or adhesive is fed through the head, and with an intermediate reservoir for storing ink or other liquid within the head.

The applicator head of the present invention can be used with a wide range of liquids for many purposes and can be used intermittently and where liquids are to be delivered without the use of compressed air or other propellant media. However, as mentioned above, droplets depending on the required technology can be used to apply fast-drying inks and adhesives to a wide range of products, especially adhesives to labels that are affixed to bottles, containers, and other articles. They find particular use in attaching labels to the articles themselves, or attaching them to the articles themselves for later application of labels. The invention therefore provides a method for attaching one object, in particular a label, to another object by adhesive means, characterized in that the adhesive is supplied by means of the applicator head according to the invention.

The compact nature of the applicator head of the invention is particularly suitable where space demands are high and the property of being able to clean the head without having to disassemble it is particularly useful. Furthermore, the cleaned applicator head can remain in the dispensing position until it is necessary to dispense more of the same agent or other adhesives or other liquids.

As a result, new adhesive is forced to flow through the applicator head while in the dispensing position at the start of the next scan.
The stickiness can be expelled through a dispensing location. This allows the applicator head to dispense new adhesive and start a new scan in a minimum amount of time without wasting product while removing any residual water or cleaning agent within the applicator head. .

It will be appreciated that the dispensing process may be varied to suit the particular applicator head and the adhesive or other liquid to be dispensed from the head. Thus, the temperature of the dispensing fluid is raised using pressure pulses and multiple changes in flow direction, resulting in repeated dispensing and reverse dispensing during a dispensing cycle.

〔Example〕

The applicator head in FIG.
It comprises a single head 10 which is conveyed from an operating position to a cleaning position 1 in which the nozzle orifice of the head engages a cleaning member 13.

The head comprises a body 14 having a solenoid valve 16 for controlling the flow of aqueous viscous material into a nozzle orifice 17, the nozzle orifice 17 being offset from the outlet to the valve 16. Ori,
It is connected to the valve outlet by bores 20 , 21 , 22 passing through the body 14 . The bore 20 traverses a longitudinal bore 24 for supplying the injection fluid to the bores zo, zi, zz and the nozzle 17. Bore 24 is connected to an external source of injection fluid (not shown).

The bore 20 carries a pin valve 25 pivoted therein, the pin valve 25 having a valve head 28 within the bore 20 and having seal supports 31 , 32 , 33 .
, 34 having shanks 26, 27 passing through them. The free end 15 of the shank 26 protrudes from the bottom of the housing 14 and the valve head 28 is no longer in sealing contact with the O-ring 29 at the bottom of the bore 20 and is subjected to a force on one side of the compression spring 30. Acts as a button for being able to be tangled and lifted. In this way, the valve head 28 moves from the bore 24 to the bores 20, 2 until the free end 15 is pushed.
1 and 22 to seal the flow of ejection fluid into them.

The solenoid valve 16 is a commercially available valve that includes a housing 14 having an extending axial chamber 38.
It has a cylindrical casing 36 glued or otherwise secured in a bore 35 therein. Valve chamber 38
is disposed at the bottom of the bore 35 , and an annular gap 39 exists between the outer surface of the valve chamber 38 and the wall of the bore 35 .

A longitudinal hole 40 traverses the annular gap 39 for supplying sticky substance to the valve chamber 38 from an external source (not shown) via an inlet 41 and an internal hole (not shown) in the valve 16. . Above the casing 36, an electromagnetic coil 37 is wound around a magnetizable valve body 44, which is pivoted within the housing and biased downwardly by a spring 48. The body 44 carries a sealing surface 45, and the sealing surface 45
2 and act to seal and unseal between the pipe and the supply of sticky material from the hole 40. Because the vibrator 42 penetrates the O-ring seal at the top of the hole 20, sticky material can only flow into the nozzle orifice 17 when the valve 16 is actuated to lift the body 44.

The cleaning location 13 includes a generally planar plate member 49 having a resilient top surface 56 and longitudinal holes 50, 53.
and the cleaning fluid is supplied to the hole 5 from an external source (not shown).
0, 53, and the hole 50 when in the cleaning position.
, 53, the fluid is discharged from the nozzle 17. The member 49 has a recess 54 connected to the hole 53 by vertical holes 51 , 52 . An O-ring seal 55 is fitted into the recess 54, and when the head 14 is in the cleaning position, the nozzle 1
The tip of 7 fits into the O-ring seal 55. head 1
The base of 4 is stepped so that part of the base is on surface 56 when in the operating position, but the lower step of the base (nozzle 17 and pin valve mechanism 15, 26, 27, 2
8) is lifted up when the head is moved to the injection position where it is on the surface 56. The upper step of the head 14 carries a plug 57 which during operation of the head engages the recess 54 to prevent the ingress of clumps.

The support mechanism for the head 10 consists of two vertical members 1 having five plates slidably held between the two vertical members 11.
1. The head 10 is fixed to a plate 59. The plates 5 are mounted by two eccentrics 61 on a shaft 62 extending between the uprights 11 . The shaft 62 has rack and pinion drive means 64,6
5, and the effect of the eccentric wheel 61 transports the five plates upward and inward. This has the effect of transporting the head 10 from the operating position shown in FIG. 1 to the cleaning position shown in FIG.

In the variant shown in FIG. 5, plate 49 and plate 5 are moved horizontally and vertically by rams 67 and 68, respectively, so that nozzle 17 is properly seated in recess 54 and lower head 10 is in plane. Raise the head 10 until it is aligned with the plate 49 and bring the plate 49 to the side.

During operation of the head 10, the valve 16 is actuated in response to a control signal from a conventional control mechanism to cause the sticky substance to exit the nozzle 17 in a series of droplets. During this time, the pin valve mechanism 15° 26 , 27 , 28 is in the closed position, and the sticky substance flows from the hole 40 through the annular gap into the valve chamber 38 and through the pipe 42 into the hole 20 .
, 21 , 22 and to the nozzle 17 . When the application of the sticky substance is interrupted, the head 10 is moved to the spraying position in which the nozzle 17 is fitted into the recess 54 and the valve bodies 44, 45 are inserted into the pipe 4.
Seal the ends of 2. The jetting fluid is supplied through the holes 24 in the head 10 or through the holes 53 in the plate 49;
Fluid is passed through nozzle 17 and holes 20, 21 and 22 to remove any remaining sticky material. The injection fluid is in the hole 24
53, injection and reverse injection can be performed alternately as required.

The pin valve assembly can be replaced by a conventional valve actuated by input to bore 24 or 53 and modulating actuation of the applicator head under control of the control mechanism.

In the type of head shown in FIG. 6, a number of valves 16 are mounted on one head 10. For compact construction, the valves are mounted in a staggered row, with pin valve assemblies 27.33 below the valves as shown, and nozzle outlets 17, 69 arranged along a common axis.

In any of the applicator heads shown in Figure 7.8.9, the applicator head generally comprises an adjustment block 101 of metal, for example aluminum or stainless steel, the adjustment block 101 comprising a sticky substance component. longitudinal holes 102 serving as distribution manifolds for the flow of aqueous polyvinyl acetate (PVA) based
and this flow is supplied at a pressure of approximately 0.8 bar from an air pressure reservoir (not shown). Holes 102 cross through holes 103 (in many cases only two are shown) which are nearly perpendicular. Disposed within each of the holes 103 is a solenoid valve 104 secured in the hole by suitable means (not shown) and sealed by an O-ring or other sealing means 105.

Valve 104 has an inlet 106 that communicates with the bottom of hole 103 so that the valve is supplied with fluid from hole 102 . Valve 104 has an outlet 107;
is a seal fitted into the narrower continuous hole 103 and acts at the bottom of the conduit 108 as the conduit 108 for conveying the fluid from the valve to the nozzle outlet. Typically the nozzle exit is a jewel orifice 109 with a nozzle orifice having a diameter of 300 to 500 micrometers.
has. Desirably, the nozzles may be mounted on a nozzle plate assembly mounted on printhead block 101.

The operation of the valve requires printer drip (
(not shown) controlled in the usual manner by a suitable control system, the article passing through the print head, for example a label from a web of pre-printed labels which is drawn from a roll of material and cut to size by a suitable cutter. Predetermined aligned sticky droplets are deposited at predetermined locations.

The printhead is provided with a second longitudinal hole that serves as a fluid flow line for the cleaning fluid. The hole can be offset from conduit 108 as shown in FIG. 7, or intersected and aligned with conduit 108 as shown in FIG. Based on the design shown in Figure 7,
The hole connects with a tube 111 that intersects the conduit. In the case of the design shown in FIG. 9, the hole accommodates an insert tube 111 that directs the cleaning fluid into the conduit.

The hole and tube 111 are connected to a source of irrigation fluid (not shown). The tubes 111 have openings 112 in their lower surfaces where they each overlap the conduits 108 as shown. Fluid flow through tube 111 is controlled by a series of bush valves 113. In the case of the design shown in FIG. 9, each conduit as shown in FIG. 9 is separated from each other and from the supply of cleaning fluid during normal operation of the printhead. A valve must be provided on each side of the Each valve 113 has a drive stem 11 extending through a hole in the printhead 101 to provide a protruding pushbutton at the bottom of the printhead.
It has 4. Normally, the valve 113 is forced into the closed position 1, for example by a spring 115. However, when the stem is pushed as shown in FIG. 8 with the right-hand valve of FIG. , allowing it to flow out of the nozzle 109.

In normal operation, the valves are positioned as shown in FIG. 7 with all stems 114 fully extended to prevent cleaning fluid from entering conduits 108 and to isolate each conduit from each other. . When movement is interrupted and it is desired to clean conduit 108 and nozzle orifice 109, head 101 is retracted so that the bottom surface supports platform 120. Platform 120 has a series of recesses 121 adapted to receive nozzles 109 and a series of holes connecting the recesses 121 to a cleaning fluid discharge line 122. Stem 114 is connected to platform 12
The stem 114 is pushed in as the print head is positioned onto the platform to support it against the top surface of the printhead 100 and allow cleaning fluid to flow through the conduit 108 and nozzle 109. Preferably platform 1
The front surface of 20 may be chamfered, beveled, or otherwise configured so that stem 114 can be progressively pushed in as print head 101 moves laterally onto the platform. Movement of the printhead from an operative position with the platform removed to an inoperative position located on the platform may be accomplished by a suitable mechanism.

Instead of actuating the valve stem 114 by positioning the printhead onto the platform 120, the valve can be actuated by any other suitable mechanism in which the printhead remains stationary.

In a particular example using the printhead of FIG.
0.8ba for applying adhesive to pre-printed labels applied to containers by pressure pad or air blast
40 through a fast-acting solenoid valve under a pressure of r.
Water-based PVA adhesive is pumped to the jewel nozzle outlet with a 0 micrometer diameter orifice. The diameter of the conduit that carries adhesive from the valve to the nozzle is 1.4 mm.
, the irrigation fluid tube is 1.0 mm in diameter and is mounted diametrically across the conduit with a 0.3 mm diameter outlet oriented axially along the conduit.

The pin valves 13, 14, 15 are shown in FIGS. 7-9 to be replaced by electrically and pneumatically actuated valves and to replace the control mechanisms that would otherwise regulate the operation of the applicator head. It will again be understood that the present apparatus may be modified.

[Brief explanation of the drawing]

1 is a diagrammatic longitudinal cross-sectional view of the applicator head in the operating position; FIG. 2 is a partial cross-sectional view of the head of FIG. 1 in the cleaning position; and FIG. 4 is a front cross-sectional view of the mechanism of FIG. 3; FIG. 5 is a side view of a different mechanism than that shown in FIG. 3; FIG. 6 is a side view of the mechanism shown in FIG. FIG. 7 is a diagrammatic front view of several applicator heads mounted in the operative position; FIG.
The figures are a similar view of the head of FIG. 7 in the cleaning position, and FIG. 9 is a longitudinal section of another version of the head of FIG. 7. DESCRIPTION OF SYMBOLS 10... Applicator head, 16... Valve, 17... Nozzle orifice, 15, 26, 27, 28... Pin valve mechanism, 20, 21, 22, 24... Bore, 13,
49...Cleaning member.

Claims (1)

Claims: 1. A fluid applicator head in which fluid is ejected in a series of droplets through a nozzle orifice, the head being capable of being cleaned by passing a cleaning fluid through the nozzle orifice; a first operative position in which the fluid applicator head is capable of applying a droplet of fluid to an object disposed opposite the nozzle orifice; and a second operating position in which the nozzle orifice engages a cleaning member incorporating a fluid communication passageway. A fluid applicator head, characterized in that it is adapted to be moved to and from a cleaning position, thereby allowing cleaning fluid to flow through a nozzle orifice. 2. The fluid applicator head according to claim 1, wherein the flow of fluid to the nozzle orifice is controlled by a solenoid valve. 3. The cleaning position comprises a member suitable for seating the area of the applicator head adjacent the nozzle orifice through which the cleaning fluid can flow in one or both directions through the nozzle orifice. A fluid applicator head according to claim 1, characterized in that: 4. The applicator head corresponds to a cleaning member having a surface suitable for receiving in sealing engagement a nozzle exit face of the applicator head and a passageway for receiving cleaning fluid from the nozzle orifice and/or from the source of cleaning fluid. Fluid applicator head according to claim 1, characterized in that it is adapted to undergo reciprocating and/or pivoting movements in order to move. 5. A first fluid passage that allows fluid to flow to a nozzle orifice located at the end of the fluid flow passage, and a hole that intersects with the first fluid passage and allows fluid to flow into the first fluid passage. a second fluid passageway with a hole disposed within the first fluid passageway and oriented substantially along an intended flow line of fluid through the first fluid passageway; A fluid applicator head according to claim 1, characterized in that: 6. The second fluid passageway is provided as a substantially cylindrical tube passing diametrically through the first fluid passageway, the hole for the second fluid passageway extending substantially along the length of the first fluid passageway. 6. A fluid applicator head according to claim 5, characterized in that it is axially located. 7. The second fluid passageway has a planar area perpendicular to the fluid flow line through the first fluid passageway, which is between 40 and 95 percent of the cross-sectional area of the first fluid passageway at that point. A fluid applicator head according to claim 5, characterized in that: 8. Fluid applicator according to claim 1, characterized in that the cleaning fluid is supplied from the valve mechanism to the passageway used to supply fluid directly to the nozzle outlet. head. 9. Fluid applicator head according to claim 1, characterized in that the flow of cleaning fluid is prevented by a valve mechanism that is actuated when the applicator head is in the second cleaning position. 10. A block comprising a plurality of valve members, each valve member having means for receiving in sealing engagement a valve mechanism and acting as a nozzle outlet, the valve mechanism having a fluid inlet and a fluid outlet. and wherein said block has a longitudinal bore for supplying fluid from an external fluid source to a fluid inlet of each valve mechanism, and an outlet from the valve mechanism communicates with a lateral passage serving for a nozzle orifice. A fluid applicator head according to claim 1, characterized in that: 11, said block having a second longitudinal bore intersecting each of the lateral passages between the valve outlet and the nozzle orifice, said second longitudinal bore directing the cleaning fluid into a second an outlet for axially feeding the lateral passageway from the longitudinal bore, and the second longitudinal bore operatively for controlling the flow of cleaning fluid into the lateral passageway. 11. A fluid applicator head as claimed in claim 10, having associated valve means. 12. A nozzle orifice is carried on the underside of the applicator head, and the applicator head is moved between the first working position and the second cleaning position by means for producing horizontal and vertical motion components. of the patent claim, wherein the underside of the applicator head carrying the nozzle orifice is seated downwardly on the seat in the cleaning position to ensure sealing engagement between the applicator head and the seat. A fluid applicator head according to scope 1. 13. The cleaning position comprises a generally flat sheet member, the sheet member having a port on its upper surface associated with a fluid transfer passageway for supplying or removing cleaning fluid, and the base of the applicator head cooperating with the upper surface. 13. A fluid applicator head as claimed in claim 12, characterized in that the fluid applicator head operates to align a nozzle orifice with the port. 14. A method for intermittently applying a first fluid to an object, the method comprising ejecting a droplet of the first fluid from a nozzle orifice while the applicator head is in the actuated position, and applying the first fluid to the object. When it is desired to interrupt and clean the applicator head,
from a position to a second position and causing a cleaning fluid to flow through a nozzle orifice to remove the first fluid from at least a portion of the flow path of the first fluid through the applicator head. The first feature is that
A method of applying fluid to an object intermittently. 15. The method of intermittently applying a first fluid to an object according to claim 14, wherein the first fluid comprises a water-soluble adhesive component. 16. A method of intermittently applying a first fluid to an object as claimed in claim 14, wherein the cleaning fluid is water-soluble. 17. A method of intermittently applying a first fluid to an object as claimed in claim 14, wherein residual cleaning fluid is subsequently removed from the applicator head. 18. A method of intermittently applying a first fluid to an object as claimed in claim 14, wherein the adhesive is applied to an object and the object is then adhered to another adhesive. .