GB2072586A - Gutter for an ink jet array printer - Google Patents

Abstract

A gutter for use in an ink jet array printer which comprises an elongate hollow body from one side of which projects a row of drop interception funnels which open into the hollow body and serve to collect unprinted ink drops is characterised in that the elongate hollow body (11) and interception funnels (18, 18%, 18_, 18>, 18__) are formed as a thin-walled unitary structure. <IMAGE>

Description

SPECIFICATION Gutter for ink jet array printer This invention relates to printing liquid jet array printers. Such printers employing one or several rows of liquid jet printing guns and serving as pattern printers are described, for example, in United Kingdom Specifications Nos. 1 354890 and 1432366, though when employing one row only of liquid jet printing guns they may be used for character or facsimile printing. The printers described in these specifications comprise one or several rows of liquid jet printing guns each gun having means for supplying printing liquid under pressure to an orifice, means for forming regularly spaced drops in the liquid stream issuing from the orifice, means for charging and deflecting and printing on a substrate drops selected from those formed in the liquid stream and means for intercepting and collecting unprinted drops.Printing liquid is hereinafter referred to as "ink" though it will be appreciated that liquid dye as well as liquid ink is to be comprehended within that term.

The ink jet intercepting and collecting means are known in the art as "gutters" and they intercept and collect unprinted drops in the drop streams from the printing guns during printing and, preferably, also during start-up and close down of the array printer.

A typical ink jet printer where, say, eight drops per millimetre can be printed, has a row of printing guns which includes sixty or more guns in line, and the accuracy of each gun is required to be within a quarter of a drop pitch. As the substrate advances below the printing guns the latter deposit on the substrate successive lines of printed drops. Each printed line comprises contiguous line sections within which the respective guns deposit selected drops from a raster of drops issuing therefrom. The preferred shape of the gutters derived from the geometrical constraints of individual rasters of drops and the necessity for clean interception, collection and removal from the drop streams without splash of unprinted drops.

Hitherto ink jet array printer gutters have been fabricated from components and this has made it difficult to locate with sufficient preci sion the ink drop interception points thereof and to ensure the prevention of occasional interception of drops intended for printing. It is an object of the present invention to provide for use in an ink jet array printer an improved form of gutter in which the shortcomings referred to are eliminated or substantially diminished.

The present invention consists in a gutter for use in an ink jet array printer comprising an elongated hollow body from one side of which projects a row of drop interception funnels which open into the hollow body and serve to collect unprinted ink drops, characterised in that the elongate hollow body and interception funnels are formed as a thinwalled unitary structure.

Preferably, the body and funnels are formed from metal by electrolytic deposition.

The invention further consists in an ink jet array printer of the kind set forth characterised by having a gutter preferably formed from metal by electrolytic deposition and comprising a thin walled unitary structure having an elongate hollow body from one side of which projects a row of drop interception funnels which open into the hollow body and serve to collect unprinted ink drops.

The invention will now be described, by way of example, with reference to the accompanying somewhat diagrammatic drawings, in which Figure 1 is a perspective fragmentary view to an enlarged scale of a single row ink jet array printer incorporating a drop interception and collection gutter in accordance with the invention, and Figure 2 is a perspective view to an enlarged scale of a former for use in the manufacture of an ink jet array printer gutter in accordance with the invention.

Referring first to Fig. 1, an ink jet array printer comprises a single row 1 of printing guns 3, 3', 3", 3"', of which only the parts required to describe the present invention have been illustreted.

Print drop streams formed from jets issuing from ink orifices descend in respective guns in the paths 4, 4', 4", 4"' etc. between pairs of deflection plates 5, 5', 5", 5"' where drops which are charged for printing are deflected to print positions on a printing substrate 6 which travels in the direction indicated by arrow 7, at right angles to the row 1 of printing guns.

Between the deflection plates and the printing substrate is mounted a drop interception and collection gutter 10 which includes a hollow, elongate drop collection body 11 extending below the deflection plates. The body 11 is located rearwardly, in the sense of substrate level, of a plane 1 2 containing the drop flight paths 4, 4', 4", 4"' entering the deflection plates and comprises top bottom and end walls 13, 14 and 1 5 secured to a vertical backing wall 1 6 and a front wall 1 7 parallel with the wall 1 6. Projecting forwardly from the front wall 1 7 through the plane 1 2 are a row of funnels 18, 18', 18", 18"', 18"", which open through the wall 1 7 into the body and provide upwardly facing apertures 19, 19', 19", 19"', 19"", centred on the respective uncharged drop flight paths 4, 4', 4", 4"'. The funnels accordingly collect uncharged drops such as drops 20, 20', 20", 20"' in the flight paths below which they are located and forther collect deflected unprinted drops 21, 21', 21" from adjacent gun flight paths. Thus unprinted drops 21 deflected from flight path 4 are collected by funnel 18.

Likewise unprinted drops 21' deflected from flight path 4' and unprinted drops 21" deflected from flight path 4" are collected by respective funnels 18" and 18"'.

The outer surfaces of the funnels 18 to 18"" are shaped in a generally downward tapering configuration to permit the passage of printing drops 22 to 22"' which are printed for correspondind drop rasters in each printing gun in contiguous line sections 23, 23', 23" of a print line 24 on the substrate such print lines being successively deposited as the substrate advances.

On the bottom wall 14 of the gutter 10 is a porous sheet 25 facing the printing surface of the substrate 6 which collects and absorbs spray from ink splashes on the substrate. In operation a slight vacuum prevails in the gutter 10 which induces flow into the gutter body 11 of ink in the sheet 25 through holes, such as hole 26, distributed at intervals along the wall 14 of the gutter. The vacuum also draws into the gutter body any ink spray which may arise from drops striking the inner walls of the funnels 1 8 to 18"". To limit the incidence of such spray, the front walls of the funnels are located well forward of the plane containing the drop flight paths 4 to 4"', and the undersurface of the funnels is sloped downwards and rearwards where the drops impact the inside of the funnels at an angle generally exceeding fifteen degrees.

A pipe (not shown) connects with the body 11 through the bottom wall thereof to afford recirculation of ink Referring now to Fig. 2, there is therein illustrated a former 30 made from electrically conductive material on which the gutter 10 of Fig. 1 is made by electrolytic deposition. To that end the former is shaped to correspond with the gutter and is coated with insulating material in the shaded areas shown to prevent deposition on those areas, there being effected on the unshaded areas deposition of a thin wall of metal suitably 25-100 microns thick.

The former 30 has deposited thereon a layer of nickel which can be directly deposited on a first layer of copper, the thin metal layers being released from the former to provide the front, top, bottom and end walls and the funnels of gutter 1 0. Although metal builds up almost uniformly on the conductive areas of the former, slight accumulations tend to occur at corners. These can be minimised by slight curving of the regions concerned on the former.

It will be appreciated that the former 30 is very precisely made to ensure that the location and form of the gutters are compatible with the printing accuracy required of the printer. This means that substantially all unprinted drops are, in operation, collected in the funnels intended for printing are not intercepted. Being of one piece construction the funnels are more accurately positioned mutually than is possible where the gutter is of fabricated form. Further the thin walled construction makes for the maximum space for the passage of printed drops after making allowance for drop flight path tolerances.

Whilst the gutter manufacture has beendescribed with reference to electrolytic deposition, other techniques, such as spraying or vacuum forming may be employed to accomplish the described one piece thin walled metal construction.

It will be appreciated that though the printer of the embodiment of the invention described is of the web feed type, the specific form of printer may be different, for example, sheet fed, and this may call for somewhat different design of gutter body and funnels.

Claims (11)

1. A gutter for use in an ink jet array printer comprising an elongate hollow body from one side of which projects a row of drop interception funnels which open into the hollow body and serve to collect unprinted ink drops, characterised in that the elongate hollow body (11) and interception funnels (1 8, 18', 1 8", 1 8"', 18"") are formed as a thinwalled unitary structure.

2. A gutter as claimed in Claim 1, characterised in that the body (11) and funnels (1 8, 18', 18", 18"', 18"") are formed from metal by electrolytic deposition.

3. A gutter as claimed in Claim 2 characterised in that the gutter is formed from nickel.

4. A gutter as claimed in Claim 3, characterised in that the gutter is formed with an inner type of copper and an outer layer of nickel.

5. A gutter as claimed in any preceding claim, characterised in that the walls of the body (11) and funnels (18, 18', 18", 1 8"', 18"") are of thickness in the range 25 to 100 microns.

6. A gutter as claimed in any preceding claim, characterised in that the body (11) includes top, bottom and end walls (13, 14 and 15) and a front upright wall (1 7) from which the row of funnels (18, 18', 18", 18"', 18"" projects forwardly and are formed with respective upwardly facing apertures (1 9, 19', 19", 19"', 19"")

7. A gutter as claimed in any preceding claim, characterised in that the funnels are of generally downwardly tapering form and are shaped to allow the passage between successive funnels of charged ink drops intended for printing.

8. An ink jet array printer of the kind set forth characterised by means for intercepting and collecting unprinted ink drops in the form of a gutter (10) as claimed in any one of the preceding claims.

9. A printer as claimed in Claim 8, characterised in that a porous sheet (25) is attached to the underside of the gutter for collecting drop splashes from a printing substrate and communicates with the interior of the gutter body by holes (26) formed on the underside of the gutter, whereby on application of vacuum to the gutter body (11) flow is induced of ink absorbed by the sheet into the gutter body.

10. A gutter for use in an ink jet array printer, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

11. An ink jet array printer of the kind set forth including a gutter in accordance with Claim 10.