JPH0513833B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to so-called "ink-jet"
or to the field of non-contact fluidic printers, also known as "fluid-jet" devices. especially,
This invention relates to an apparatus for substantially damping turbulence in a fluid supply reservoir of an ink-jet or fluid-jet device.

[Prior Art] The ink-jet device itself is described in U.S. Pat.
No. 3560988, also No. 3579721 by Mr. Kaltenbatscha
No. 3596275 of Mr. Sweet, etc. These ink-jet devices characteristically include a linear array of fluid-jet orifices formed in an orifice plate through which a filament of pressurized printing liquid (e.g., ink, dye, etc.) is delivered. is forced out of the fluid supply tank. Below the orifice plate, separately controllable electrostatic charging electrodes are arranged along a so-called drop formation zone. In accordance with the well-known principle of electrostatic induction, each fluid filament is provided with a potential opposite in polarity and proportional in magnitude to the potential of the charging electrode. When a droplet of fluid leaves the filament, an induced electrostatic charge is loaded onto the droplet. Thus, as the charged droplet continues to pass through a static electromagnetic field having the same polarity as its charge, the charge causes the droplet to deviate from its normal path and towards the droplet collector. On the other hand, uncharged droplets follow the normal path and eventually deposit on the substrate.

Recently, the use of ink-jet devices as a means of printing patterns and the like on fabrics has been proposed, and U.S. Pat. The main point of this disclosure is that in order to print fine patterns on fabric, for example, the diameter
In this case, it is necessary to use an orifice plate with very small orifices of about 0.01 to 0.5 mm arranged in a straight line. Or the problem arises that multiaxial flow has a very negative effect on droplet formation. In other words, turbulence in the fluid supply tank causes irregular charging and deflection of the droplets, resulting in incomplete printing of the fabric.

In order to better understand the novelty of this invention, which will be described later, let us briefly explain the following US patents. namely, No. 4080607 of Mr. Von Bremen et al., No. 4403228 of Mr. Miura et al., No. 4260996 of Mr. Uittwer;
No. 4167742 of Mr. Hetsudo and others, and No. 4419673 of Mr. Ebi and others.

- No. 607 has a net-like inlet plate 75 in the composite tank upstream of the orifice plate 60, and the orifice plate 60
A method of attenuating turbulence in a fluid or ink supplied to an apparatus is disclosed. The described mesh entrance plate 75 is a relatively coarse mesh (ie, 0.3 mm, or 35 mesh), single piece mesh with a mesh spacing of 0.5 mm.

- In the disclosure of No. 228, the network structure 101 is in contact with the ink in the opening 102 formed in the frame 100, and it should be noted that FIG. 14 and from line 65 of column 5 This is up to the fourth line of column 6. The function of the disclosed network structure 101 is to provide a meniscus-forming surface on which a plurality of menisci are formed and maintained.

- No. 996 discloses an ink-jet head with an ink droplet aspirator. This aspirator has a filter of 17.1
8, where the passage of air is smoothed, reducing turbulence and making the air through the tunnel 31 as close as possible and laminar.

- No. 742 discloses a structure that acts as a damping means for moving vibration waves within an orifice plate.

- No. 673 simply discloses providing a filter in the flow path to remove impurities from the fluid.

SUMMARY OF THE INVENTION The present invention is directed to a device that effectively damps turbulence in a fluid supply tank of an ink-jet device. It may be difficult to fully understand at this point how this invention effectively damps turbulence, but in short, the composite structure of this invention:
Multi-axial flow or turbulent flow patterns (i.e., so-called eddy currents) in the fluid are attenuated or substantially eliminated, and the fluid flow is controlled in the fluid supply reservoir directly above each orifice in the orifice plate. This makes the flow substantially uniaxial. Thus, the present invention completely attenuates the turbulence present in the fluid supply tank and provides adequate jet flow through the orifice.

These advantages of the invention are realized by a composite structure having a planar central support member and upper and lower damping members abutting each other on the upper and lower surfaces thereof. The central support member is disposed within the fluid supply reservoir and defines upper and lower sub-supply reservoirs. The central support member serves, in part, to increase the structural rigidity of the composite damping structure and prevents the structure from collapsing due to pressure differentials as fluid flows from the upper supply reservoir to the lower supply reservoir. The central support member has a relatively large diameter (ie, about 10 mm diameter) opening along its entire length to form a turbulent stationary zone between the upper and lower damping members.

The upper and lower damping members are provided with a fairly close density of holes to effectively dampen the multiaxial flow pattern of the fluid passing therethrough.

This invention provides stepwise attenuation of turbulence when fluid flows between upper and lower sub-supply tanks. That is, the upper damping member first damps the multiaxial flow pattern of the fluid as it flows from the upper secondary supply tank to the stationary zone of the central support member. The fluid that has undergone this primary damping comes to rest in the stationary zone, then passes through the lower hole of the lower damping member, and any remaining multiaxial flow is damped. The upper hole is preferably of larger size (i.e., about 30-40 mesh) compared to the size of the lower hole (i.e., about 75 mesh), thus providing the gradual attenuation described above. .

The relatively large top hole also allows air to escape that is trapped in the stationary band during start-up of the ink-jet head used in the present invention. In other words, the air that was prevented from flowing from the stationary zone to the lower supply tank due to the relatively small diameter of the lower hole can now escape through the upper hole because of the relatively large diameter. be. The air collected in the upper sub-supply reservoir is then purged before the ink-jet head begins printing, ensuring that the liquid supply reservoir is substantially free of entrained air.

The advantages of this invention will become clearer from the examples described below.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, the turbulence-damping composite structural zone 10 of the present invention is fixedly mounted within a fluid supply reservoir 12 of an ink-jet print head 14 upstream of an orifice plate 16. Upper and lower sub-supply tank 1
8 and 20, respectively. Print head 14
preferably comprises a pair of upper and lower composite members 22, 24 to which the turbulence damping structure 10 is attached. Suitable machined threaded bolts 26 or the like connect the upper and lower composite members 22, 24 together. The lower composite member 24 is preferably provided with an opposing recessed surface 28 for receiving a support rod 30 (see FIG. 2) attached to the turbulence damping structure 10;
The structure 10 is supported in the set position of the supply tank 12. A suitable resilient sealant 32 is provided on the lower composite member 24 and seals the upper and lower composite members 2.
2 and 24 to prevent fluid leakage.

The orifice plate 16 is attached to the lower end of the lower composite member 24 by clamping means 34, 36 which are rigidly connected to the lower composite member 24 in a manner not shown. The orifice plate 16 is also sealed with a resilient seal 38 to prevent fluid leakage.

Fluid supplied to supply tank 12 from fluid source 40 passes through turbulence damping structure 10 and then to orifice plate 16, through orifices 16b disposed therein, and through at least one fluid jet 16a. is formed. The fluid jet 16a is charged by the charging electrode 16c, which fluid jet is provided with a potential opposite in polarity and proportional in magnitude to the potential of the charging electrode 16c, as is well known. The charged droplets separated from the fluid jet 16a (note the dotted lines in FIG. 1) are deflected by the deflection electrode 16d toward the droplet collector 16e, while the uncharged droplets (note the solid lines in FIG. 1) are deflected by the deflection electrode 16d toward the droplet collector 16e. ) continues towards the printing medium 17.

The structure of the invention is shown more clearly in FIGS. 2 and 3. As shown, the structure 10 includes a central support member 42 having adjustable features and a relatively large opening 44 aligned along the longitudinal axis of the support member 42. It is formed. Opening 44 is preferably circular;
It is best to have a diameter of about 10 mm and a center-to-center distance of about 16 mm. Other sizes and shapes can of course be used in accordance with the invention. The material constituting the central support member 42 depends on the fluid used, but it is preferable to use stainless steel (plate thickness 0.9 mm) for the central support member 42. Other metal materials and hard plastic materials can of course also be used.

Upper damping member 46 is secured to the upper surface of central support member 42, while lower damping member 48 is secured to the lower surface of support member 42. Preferably, the upper damping member 46 is a relatively open 30-40 mesh wire mesh (i.e., pore size 0.5-0.4 mm) approximately 0.6 mm thick.
It is best to use stainless steel wire with a thickness of about 0.3 mm. Thus, the relatively coarse holes 50
is formed by the network structure of the upper damping member 46, which allows passage of fluid and air and serves to dampen the initial flow of fluid.

On the other hand, the lower damping member 48 preferably has a dense array of fine holes to further dampen the multiaxial pattern of the fluid. As mentioned above, the small size of the lower hole (preferably a 75 mesh or circular hole of about 0.2 mm diameter) prevents air from passing through the hole at the start of operation. Air, however, can pass upwardly through a large upper hole 50 provided in the upper damping member 46, collects in the upper part of the supply tank 12, and is removed by the removal means 54 (FIG. 1). reference).

Arranging the composite turbulence damping structure 10 as described above provides the following advantageous functions. The fluid flows along the cross section of the structure 10 (arrow 50 in FIG.
4), first the upper damping member 4
Meet 6. When liquid passes through the holes 50 of the upper damping member 46, most of the multiaxial flow present upstream of the member 46 is effectively attenuated by the damping effect of each wire forming the holes 50. This primary damped fluid then flows into the adjustment opening 44, where the upper and lower damping members 46, 4
8 function as turbulent stationary zones provided independently. That is, members 46 and 48
By temporarily stopping the fluid in the opening 44 sandwiched between the two, it is easy to completely attenuate the multiaxial flow pattern remaining in the fluid when it next passes through the damping member 48 and the hole 52 attached thereto. become.

Thus, it is presumed that directly below the lower damping member 48, the multiaxial flow of fluid that existed upstream of the upper damping member 46 is substantially attenuated and becomes a uniaxial flow in the direction of arrow 504. The composite control structure 10 provided by the present invention as an improvement thus provides a uniaxial flow of fluid directly above the orifice plate 16 that is substantially perpendicular to the orifice plate 16 and directs the flow of fluid directly above the orifice plate 16 into a uniaxial flow substantially perpendicular to the orifice plate 16. Orifice 1 provided
This increases the fluid jet formation efficiency of 6b.

Upper and lower damping members 46, 4 of structure 10
8, or the material used for the central support member 42 is
Although stainless steel is mentioned as being preferred, other metallic and/or non-metallic hard materials are of course possible. however,
Such materials depend on the type of fluid being handled and the supply tank 12.
It must be determined by taking into account the working pressure within. This invention has been described with reference to the embodiment considered to be the most preferable at the present time, but of course various modifications based on the novel idea of this invention are envisaged, and all of these modifications are within the scope of the claims of this invention. Naturally, it is included in the described device.

[Brief explanation of the drawing]

FIG. 1 shows ink using the apparatus according to the present invention.
FIG. 2 is a plan view including a partial cross section of the apparatus of the present invention; FIG. FIG.

Claims (1)

[Claims] 1. The upper and lower surfaces and the upper and lower sub-supply tanks 18, 20 by being fixed in the supply tank 12.
a central support member 42 having opposed ends forming a central support member 42 and including a plurality of openings 44 therethrough;
and upper and lower portions defining upper and lower holes 50, 52, respectively, and respectively associated with the upper and lower surfaces of the central support member, the openings forming stationary zones, respectively, between the upper and lower damping means. damping means 46, 48, when the fluid flows from the upper sub-supply tank through the upper hole into the stationary zone, the upper damping means first damps the multiaxial flow of the fluid; the lower damping means further damping the multi-axial flow of the fluid as the fluid flows from the stationary zone through the lower hole to the lower sub-supply tank, the lower damping means further damping the multi-axial flow of the fluid into at least one continuous droplet of fluid; A turbulence damping device for a fluid supply tank of an inkjet printing head that damps multiaxial flow of fluid directly above a row-generating orifice plate 16. 2. The device according to claim 1, wherein the upper hole is formed by a mesh structure of 30 to 40 meshes. 3. The device of claim 1, wherein the openings in the central support member are each circular openings having a diameter of approximately 10 mm. 4. Claim 1, wherein the lower holes are each comprised of approximately 75 mesh holes arranged closely together.
The equipment described in section. 5 an orifice plate 16 associated with said inkjet printing head for producing a linearly arranged stream of fluid droplets; and means 16c for charging selected droplets in the stream of droplets; 16. The apparatus of claim 1, further comprising: means 16d for deflecting said selected droplet from the normal flow path of the droplet towards a droplet collection structure 16e. 6. Means 26, 30, 32 for said inkjet printing head to be provided with fluid multi-axial flow attenuation means 10 and for forming opposing recessed surfaces 28 for mounting said attenuation means in a precise position within the head. 6. The apparatus of claim 5, comprising: 7. The damping means 10 includes a support rod means 30 fixed below and perpendicular to the lower damping means 48, which spans the opposing recessed surfaces to connect the damping means 10 to the fluid supply tank. 7. The apparatus of claim 6, supported in a 12.