US3458761A - Writing head producing a jet of ink - Google Patents

Description

July 29, 1969 E. ASCOLI WRITING HEAD PRODUCING A JET OF INK Filed July 6, 1967 2 Sheets-Sheet 1 0 M0 3 3 b d 8 J g 0 fi. Z m a r f WW a n 3 2 I H I 1|ll| J H 28 9 4 (I 4 5 5 H INVENTOR ENzo flue/4 BY W ATTORNEY July 29, 1969 Filed July 6, 1967 E. ASCOLI WRITING HEAD PRODUCING A JET OF INK 2 Sheets-Sheet 2 INVENTOR ATTORNEY United States Patent 3,458,761 WRITING HEAD PRODUCING A JET 0F INK Enzo Ascoli, Lausanne, Switzerland, assignor to Paillard S.A., Vaud, Switzerland, a company of Switzerland Filed July 6, 1967, Ser. No. 651,457 Claims priority, application Switzerland, Feb. 13, 1967,

2,088/ 67 Int. Cl. G01d 15/16, 15/18 U.S. Cl. 317-3 3 Claims ABSTRACT OF THE DISCLOSURE An electrically controlled writing head, wherein the same longitudinal fraction of the jet of ink is subjected simultaneously to the action of a pair of horizontal deflecting electrodes and of a pair of vertical deflecting elec trodes. Said electrodes are constituted by plates arranged in pairs interengaging each other as provided by the notching of their cooperating edges perpendicular to each other and to the axis of the jet.

Background of the invention Writing heads producing a jet of ink are already known which include a body carrying a tube forming a nozzle for the jet of ink and jet-deflecting electrodes located to either side of the axis of said tube.

In such writing heads, it is of interest to reduce its bulk as much as possible and to draw faithfully the character of which the outline is defined by the voltages applied to the deflecting electrodes.

Summary of the invention The present invention has for its object means reducing substantially the length of the writing head and chiefly cutting out any deformation of the character to be drawn, which deformation is ascribable to the duration of progression of the jet of ink as it passe between the first pair of electrodes and then between the second pair, in the case where said two pairs of electrodes are located in sequence along the path of the jet of ink.

As a matter of fact, duringthe progression of the jet from one pair of electrodes to the next, the deflecting voltage applied to the second pair can be modified and consequently the phase relationship between the horizontal and vertical deflecting voltages would no longer remain unaltered.

The present invention has for its object a reading head projecting a jet of ink, of the type including a body'carrying a tube forming anozzle for the jet'of ink and jet deflecting electrodes arranged pairwise to either side of the tube axis. This invention consists in that the electrodes are constituted by similar plates provided each with two notches along one edge so that the notched sections of the two plates serving for vertical deflection engage without any direct contact therewith, the notched sections of the two plates serving for horizontal deflection. Thus, all

deflecting electrodes extend in registry with the same por- I FIGS. 2 and 3 are transverse cross-sections through lines II--II and III-III of FIG. 1. 7

FIG. 4 is a perspective view of the electrode system.

, Description of the preferred embodiment.

The reading head illustrated includes a metal body 1 of which the cylindrical section 2 serves as a support for 3,458,761 Patented July 29, 1969 a coaxial bell-shaped member 3 of insulating material. Said bell-shaped member is merely slid over said cylindrical section 2 which is provided with longitudinal slots 4 adapted to increase its elasticity. The bell-shaped member 3 may be obtained through molding and it includes a transverse partition 5 provided with an annular series of openings 6 and rigid with a sleeve-shaped coaxial member 7. Said sleeve-shaped member 7 forms a unit with the bell-shaped member 3 and may be cast for instance therewith out of a synthetic material such as that sold under the registered trade name nylon. The sleeve 7 serves as a support for a metal annulus 8 inside which is set a tube 9 forming a nozzle projecting the jet of ink. The ink is fed to the tube 9 through a yielding pipe 10.

The body 1 carries in its medial section a transverse annular partition or wall 11 provided in its middle and in registry with the tube 9 with an opening 12 the edges of which are sharp.

The end of the body 1 opposed to its cylindrical section 2 forms four longitudinal projections 13, 14, 15, 16 of which the inwardly facing surfaces are tapered at 17. Said tappings 17 allow screwing inside the body 1, an outwardly projecting terminal metal member 18 adapted to clamp in position outside the body 1 a metal ring 19, a securing plug 20 and two rings of insulating material 21 and 22 in contacting relationship with a peripheral shoulder 23 provided on the outer surface of the body 1.

The two rings 21 and 22 serve as carriers for four plates 24, 24', 2 5, 25 forming the electrodes deflecting the jet of ink projected out of the tube 9 through the opening 12 in the annular partition 11. The surfaces facing each other on the rings 21 and 22 are provided with grooves 21 and 22 respectively, which serve as guides for the electrode plates. As illustrated in FIGS. 1 and 3, the plates 24 and 24 are provided each with two notches a, whereas the plates 25 and 25 show each two notches b. The plates 24, 24, 25, 25 are furthermore given substantially the same shape and are arranged'pairwise at right angles and in opposite relationship. Said arrangement allows interengaging said plates'without any electric contact between them, the plates 24,24"1ying in two vertical parallel planes and the plates 25, 25 in two horizontal planes. Said interengaging plates occupy thu a minimum space in a direction parallel with the axis of the tube 9. Thus,'the particles of ink pass simultaneously between the horizontal deflecting platesand the vertical deflecting plates. This leads to an important advantage since,if the pairs of deflecting plates were arranged in sequence along the path of the jet of ink, this would lead to a'deformation of the character drawn by it a a consequence of the time required for the progression ofthe particles from one pair ofplates to the next. The structure disclosed thus cutsout completely said'drawback. It should be mentioned that no part of insulated material is apparent to view from any point of observation located at theend of the nozzle tube 9. As a matter of fact, said end of'the tube 9 cannot possibly see the bell-shaped member 3 made of insulating material, which member is concealed by the inner annulus 8 and the outer cylindrical section 2. Similarly, the two insulating rings 21 and 22 are concealed by the annular portition 11. Thus, the electric field extending between the tube 9 and partition 11 is not subjected to the action of the electric loads which may be carried by the parts of insulating material as provided for instance by a capacitory influence.

In order to reduce as much as possible any parasitic action as a consequence of the static loads carried by the insulating parts, the two rings 21 and '22 are spaced with reference to the path followed by the jet of ink by the projections 13 to 16 on the support 2 and also by the intermediate projections 26 (FIG. 3) inserted between the former projections. Thus, the jet of ink is protected to a maximum extent against any parasitic action ascribable to the static loads possibly carried by the insulating parts. Furthermore, the sole parts of the jet of ink which might be subjected to some slight action of the static loads carried by the rings 20 and 22 extend between the opening 12 and the entrance of the jet into the passage defined by the electrodes and also between the output of said passage and entrance of the openings 27 defined by the terminal metal member 18.

It should be remarked that the plates 24, 24', 25, 25' project beyond the outer periphery of the rings 21 and 22 so that it is possible to weld thereto conducting wires adapted to give said plates the desired instantaneous voltage.

The voltage applied to the tube 9 is transmitted either by the conductive ink or else by a metal lead which may, as a matter of fact, b inserted inside the yielding pipe 10.

As soon as the ditference in voltage between the partition 11 which is generally grounded and the tube 9 is sufliciently high, the ink escaping out of said tube forms a jet constituted by a succession of droplets. Said jet passing between the deflecting electrodes is shifted under the action of the voltages applied to said deflecting electrodes.

Preferably, the carrier parts made of metal, that is the parts 2, 20 and 18 are subjected to the same voltage as the support carrying the surface to be written over. Consequently, the electric field between the opening 27 in the terminal member 18 and said surface showing the point of impact for the jet of ink is equal to zero and the path of the jet of ink can therefore no longer be modified between the output of the writing head and said point of impact onto the writing surface.

The extremely small ink droplets forming the secondary jet escape within a cone the apical angle of which is large and are arrested by the partition 11. The latter is polished and the edge of the opening 12 therein is very sharp so that the droplets forming the secondary jet cannot collect on such a sharp cutting edge by reason of the surface pressure of the ink droplets. Furthermore, the sharp edge of the opening 12 merges into the surface of the partition 11 facing the tube 9 along a convex annular surface 11a which is also polished so as to further the coalescence of the extremely small ink droplets which may settle on said annular surface. Said droplets form thus a continuous annular sheet of ink which flows steadily towards anoutput port opening into the depending tube '28 as furthered by a verticalgroove 29 extending between the convex surface 11a and said output port.

The above-described writing head shows numerous advantages over those proposed hitherto. As a matter of p the like objectionable actions.

By reason of the shield formed by the metal parts carrying the head, the electricfields inside said head remain valways uniform and their values are well-defined. Said fields can be deformed neither by. outerparasitic fields, nor under the action of the, static loads which may collect on the insulating parts.

The openings 6 formed in the partition 5 allow air to enter the writing head so as to replace the air escaping through the opening '27 and which is carried along by" the moving jet of ink; 'Thus, the air pressure inside the head remains substantially constanttwhich is essential with a view to obtaining a clean writing.

be system of carrierparts isrigid with the securing lug 20 as provided by the mere screwing of the terminal member 18 inside the threads 17 cut in thelongitudinal projections 13 to 16. To this end, the terminal member 18 is provided along its outer edge with a slot 29' adapted to be engaged by a screw-driver. Furthermore, the insulating bell-shaped member 3 rigid with the annulus 8 and tube 9 may be removed through a mere sliding over the cylindrical section 2 of the body 1 which allows inspecting and cleaning easily said tube 9.

I claim: v v 1. In a writing head comprising a nozzle through which a jet of ink is projected, the provision of a first pair of deflecting electrode plates provided along one edge with two notches spaced by the same amount and extending in transverse registry with the location of a predetermined section of the jet projected out of the nozzle and a second pair of deflecting electrodes extending perpendicularly to the electrodes of the first pair in transverse registry with the same location and one edge of which engages the corresponding notches in the electrode plates without any contact between the plates of the two pairs.

' 2. A writing head as claimed in claim 1, wherein the electrode plates of the'second pair are also provided along their said one edges with two notches spaced by the same amount, the notched sections of the plates of said second pair engaging the notches in the plates of the first pair.

'3. A writing head as claimedin claim 1, comprising two annular rings surrounding the location of said predetermined section of the jet and provided in their cooperating adjacent surfaces with two spaced grooves in one direction and with two further spaced grooves perpendicular to the first-mentioned spaced grooves for engagement respectively by the edge of the corresponding electrode plates perpendicular to the said one edges, in the plates of the first pair.

References Cited UNITED -STATES PATENTS:

LEE T. l-IIX, Primary Examiner V

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