Pattern printing apparatus
United States Patent 3925791
Pattern printing apparatus comprising printing guns having orifices from which emerge jets of printing liquid, the improvement comprising the use, as the orifices, of discs each of which has a hole of the requisite diameter, said disc being independently mounted on the housing of each printing gun.
Application Number:
05/479178
Publication Date:
12/09/1975
Filing Date:
06/13/1974
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Export Citation:
Assignee:
Imperial Chemical Industries Limited (London, EN)
Primary Class:
Other Classes:
347/47
International Classes:
B41J2/025; B41J2/015; G01D15/18
Field of Search:
197/1R 346/75,140 239/587 101/197,366
Other References:
IBM Technical Disclosure Bulletin, Vol. 15, No. 5, Oct. 1972, Meier, "Mech. X-Y Aiming...". .
IBM Technical Disclosure Bulletin, Vol. 15, No. 3, Aug. 1972, Kotasek, "Replaceable Ink Jet Nozzle"..
Primary Examiner:
Burr, Edgar S.
Assistant Examiner:
Suter R. E.
Attorney, Agent or Firm:
Cushman, Darby & Cushman
Claims:
I claim
1. An improved adjustable nozzle for pattern printing equipment having a plurality of printing guns each having a nozzle from which emerges a jet of printing liquid, the nozzle comprising:
2. An improved nozzle as claimed in claim 1, wherein said disc is mounted on said plate.
3. An improved nozzle as claimed in claim 1, wherein said disc is positioned between said compressible member and said plate.
4. An improved adjustable nozzle as claimed in claim 1, wherein said disc comprises a synthetic sapphire.
1. An improved adjustable nozzle for pattern printing equipment having a plurality of printing guns each having a nozzle from which emerges a jet of printing liquid, the nozzle comprising:
2. An improved nozzle as claimed in claim 1, wherein said disc is mounted on said plate.
3. An improved nozzle as claimed in claim 1, wherein said disc is positioned between said compressible member and said plate.
4. An improved adjustable nozzle as claimed in claim 1, wherein said disc comprises a synthetic sapphire.
Description:
This invention relates to pattern printing apparatus and more particularly to such apparatus adapted to print by depositing on a printing surface during relative movement between the apparatus and the printing surface successive rows of closely spaced drops extending transversely to said direction of relative movement.
In Belgian Patent Specification No. 771,808 there is described a pattern printing apparatus adapted to print by depositing on a printing surface during relative movement between the apparatus and the printing surface small drops of printing liquid in successive rows of closely spaced drops extending transversely to said direction of relative movement, comprising a row of printing guns disposed transversely to said direction of relative movement, each gun having an orifice, printing liquid supply means for supplying liquid under pressure to the orifice to form a jet of printing liquid directed towards the location in the apparatus of the printing surface, means for imparting regularly spaced variations in the cross-section of the jet to stimulate drop formation, charge electrode means located adjacent the position in the jet path of drop separation to effect charging of drops formed in the jet path, drop deflection means to provide a substantially constant electrostatic field through which pass the drops formed in the jet path thereby to deflect electrically charged drops to an extent depending upon the charge levels on the drops, and, a drop intercepting device for intercepting uncharged drops formed in the jet path, characterised in that there are provided signal generating means which make available for application to the charge electrode means a periodic voltage signal the periods of which are of duration sufficient to span the formation of a plurality of drops in each jet path, and, electrical means operative to apply the signal voltage at pre-determined voltage levels during each period of the signal voltage to charge electrode means of some at least of the printing guns thereby to charge drops formed in the jet path of each gun, the charged drops from each printing gun being thereby deposited on the printing surface in the length of a line section, the line sections of the printing guns together being thus occupied by a row of drops extending transversely with respect to the direction of relative movement between the apparatus and the printing surface.
Also in Belgian Patent Specification No. 801,757 there is described a modification of the above apparatus in which, instead of intercepting in the drop intercepting device uncharged drops formed in the jet path, there are intercepted those drops which have been charged by the charge electrode means at least to a predetermined level.
In the previously described apparatus hypodermic tubes of suitable diameter are used for each of the orifices, the said hypodermic tubes being mounted in line in the housing which is attached to the manifold making up each row of printing guns. In practice it has however been found very difficult to align the hypodermic tubes making up the orifices in each row of printing guns with sufficient accuracy with the result that the drops of printing liquid which alight on the printing surface from each of printing guns in any successive row are either not all in line and/or are not evenly spaced.
It has now been found that the above-mentioned difficulty can be overcome by constructing each of the orifices from a disc which carries a hole of the requisite diameter and which is independently mounted on the housing.
Accordingly the present invention is directed to pattern printing apparatus of the type just described characterised in that each printing gun has an orifice from which emerges a jet of printing liquid, the improvement comprising the use, as the orifice, of a disc having a hole of the requisite diameter, said disc being independently mounted on the housing of the printing gun.
By independently mounting each of the discs on the housing each jet can be individually aligned thus ensuring great accuracy in the line of drops reaching the printing surface from a row of such printing guns. Preferably each disc is individually and rigidly mounted on a plate which is itself attached to the housing by an adjustable mounting, or each disc is retained in place behind a plate which is itself attached to the housing by an adjustable mounting. In both cases adjustment of the plate automatically adjusts the position of the disc thus re-aligning the jet of printing liquid.
By way of illustration a printing gun which is a preferred embodiment of the invention will now be described with reference to FIGS. I and II of the accompanying drawings wherein
FIG. I represents a vertical cross-section of the orifice and
FIG. II a view from underneath.
FIG. III which is a vertical cross-section of the orifice illustrates an alternative method of adjusting the disc, whilst
FIG. IV, which is a view from underneath, illustrates an arrangement of the plates in a row of printing guns.
The printing gun described in FIGS. I and II comprises a housing 1 which is attached to a manifold 3, the housing carrying a central hole 2 of larger diameter than that of the hole 7 present in the disc 6, and the hole 2 extending from the manifold 3 to the case of the housing 1. Attached to the case of the housing 1 by screws 8 which fit into threaded holes in the housing are a flexible compressible washer 4 made of, for example, rubber, plastic or other suitable deformable material and a plate 5, having a central hole, on which is mounted the disc 6 having a hole 7 of the requisite diameter for the nozzle of the printing gun. Adjustment of the screws 8 moves the plate carrying the disc thus re-aligning the jet of printing liquid issuing from the nozzle when printing liquid is supplied to the nozzle via the manifold 3 and the central hole 2.
A further preferred method of attaching a disc to a printing gun will now be described with reference to FIG. III of the accompanying drawings which represents a cross-section of the lower portion of the printing gun.
The printing gun comprises a housing 21 which is attached to a manifold (not shown), the housing carrying a central hole 22 which can be cylindrical or cone or horn shaped. Printing ink from the manifold passes into the central hole 22. The lower portion of the housing 21 contains a central recess 35 preferably of circular cross-section. This central recess 15 contains a flexible compressible washer 30 and the disc 26 having a hole 27 of the requisite diameter. The disc 26 and washer 30 are held in position in the central recess 35 by means of a plate 31 having a central hole 36 which is of larger diameter than the hole 27 in the disc 26. The plate 31 contains three holes 33 which correspond to holes 34 in the bottom flange 37 of the housing 21, and the plate 31 is attached to the housing 21 by means of bolts and nuts 32 which pass through the respective holes 33 and 34. Alignment of the jet of printing liquid which issues from the hole 27 in the disc 26 when printing liquid is fed from the manifold into the central hole 22 is achieved by adjustment of one or more of the bolts and nuts 32. In place of the bolts and nuts 32 there can be used bolts which fit into threaded holes in the housing 21.
The plate 31 can be circular in shape. However in view of the close proximity of the printing guns in a row to each other thus limiting the overall size of each of the plates 31 it is often advantageous to have such plates of triangular cross-section, the said plates being arranged alternatively as depicted in FIG. IV which represents a view from underneath of a number of nozzles in a row.
This particular form of the apparatus comprises a housing 41 which is attached to a manifold (not shown). Attached to the underneath of the housing 41 are a number of plates 31 of triangular shape each of which is attached to the housing by three bolts and nuts 32. Each plate 31 contains a central hole 36 which are all situated in a line running the full length of the housing 41. Positioned between each plate 31 and the housing 41 is a disc 26 having a hole 27 and a soft washer (not shown), the discs being so positioned that each of the holes 27 is in the centre of a hole 36 and the holes 27 are also situated in a line running the full length of the housing 41.
In operation printing liquid supplied via the manifold issues in jets from each of the holes 27 and alignment of these jets is achieved by adjusting one or more of the bolts and nuts 32 in each plate 31.
It is preferred that each disc comprises a jewel, such as a synthetic sapphire, having a hole of the requisite diameter. The said holes can be cylindrical, but preferably are funnel shaped (in vertical cross section) so that the printing liquid enters from the wider side of the hole and emerges from the narrow side (as depicted in FIG. III). Such a form of hole in the disc leads to much more uniform jets.
The printing guns of the present invention are used in place of the printing guns described in Belgian Patent Specifications Nos. 771,808 and 801,757, the resulting apparatus being operated in the manner previously described.
In Belgian Patent Specification No. 771,808 there is described a pattern printing apparatus adapted to print by depositing on a printing surface during relative movement between the apparatus and the printing surface small drops of printing liquid in successive rows of closely spaced drops extending transversely to said direction of relative movement, comprising a row of printing guns disposed transversely to said direction of relative movement, each gun having an orifice, printing liquid supply means for supplying liquid under pressure to the orifice to form a jet of printing liquid directed towards the location in the apparatus of the printing surface, means for imparting regularly spaced variations in the cross-section of the jet to stimulate drop formation, charge electrode means located adjacent the position in the jet path of drop separation to effect charging of drops formed in the jet path, drop deflection means to provide a substantially constant electrostatic field through which pass the drops formed in the jet path thereby to deflect electrically charged drops to an extent depending upon the charge levels on the drops, and, a drop intercepting device for intercepting uncharged drops formed in the jet path, characterised in that there are provided signal generating means which make available for application to the charge electrode means a periodic voltage signal the periods of which are of duration sufficient to span the formation of a plurality of drops in each jet path, and, electrical means operative to apply the signal voltage at pre-determined voltage levels during each period of the signal voltage to charge electrode means of some at least of the printing guns thereby to charge drops formed in the jet path of each gun, the charged drops from each printing gun being thereby deposited on the printing surface in the length of a line section, the line sections of the printing guns together being thus occupied by a row of drops extending transversely with respect to the direction of relative movement between the apparatus and the printing surface.
Also in Belgian Patent Specification No. 801,757 there is described a modification of the above apparatus in which, instead of intercepting in the drop intercepting device uncharged drops formed in the jet path, there are intercepted those drops which have been charged by the charge electrode means at least to a predetermined level.
In the previously described apparatus hypodermic tubes of suitable diameter are used for each of the orifices, the said hypodermic tubes being mounted in line in the housing which is attached to the manifold making up each row of printing guns. In practice it has however been found very difficult to align the hypodermic tubes making up the orifices in each row of printing guns with sufficient accuracy with the result that the drops of printing liquid which alight on the printing surface from each of printing guns in any successive row are either not all in line and/or are not evenly spaced.
It has now been found that the above-mentioned difficulty can be overcome by constructing each of the orifices from a disc which carries a hole of the requisite diameter and which is independently mounted on the housing.
Accordingly the present invention is directed to pattern printing apparatus of the type just described characterised in that each printing gun has an orifice from which emerges a jet of printing liquid, the improvement comprising the use, as the orifice, of a disc having a hole of the requisite diameter, said disc being independently mounted on the housing of the printing gun.
By independently mounting each of the discs on the housing each jet can be individually aligned thus ensuring great accuracy in the line of drops reaching the printing surface from a row of such printing guns. Preferably each disc is individually and rigidly mounted on a plate which is itself attached to the housing by an adjustable mounting, or each disc is retained in place behind a plate which is itself attached to the housing by an adjustable mounting. In both cases adjustment of the plate automatically adjusts the position of the disc thus re-aligning the jet of printing liquid.
By way of illustration a printing gun which is a preferred embodiment of the invention will now be described with reference to FIGS. I and II of the accompanying drawings wherein
FIG. I represents a vertical cross-section of the orifice and
FIG. II a view from underneath.
FIG. III which is a vertical cross-section of the orifice illustrates an alternative method of adjusting the disc, whilst
FIG. IV, which is a view from underneath, illustrates an arrangement of the plates in a row of printing guns.
The printing gun described in FIGS. I and II comprises a housing 1 which is attached to a manifold 3, the housing carrying a central hole 2 of larger diameter than that of the hole 7 present in the disc 6, and the hole 2 extending from the manifold 3 to the case of the housing 1. Attached to the case of the housing 1 by screws 8 which fit into threaded holes in the housing are a flexible compressible washer 4 made of, for example, rubber, plastic or other suitable deformable material and a plate 5, having a central hole, on which is mounted the disc 6 having a hole 7 of the requisite diameter for the nozzle of the printing gun. Adjustment of the screws 8 moves the plate carrying the disc thus re-aligning the jet of printing liquid issuing from the nozzle when printing liquid is supplied to the nozzle via the manifold 3 and the central hole 2.
A further preferred method of attaching a disc to a printing gun will now be described with reference to FIG. III of the accompanying drawings which represents a cross-section of the lower portion of the printing gun.
The printing gun comprises a housing 21 which is attached to a manifold (not shown), the housing carrying a central hole 22 which can be cylindrical or cone or horn shaped. Printing ink from the manifold passes into the central hole 22. The lower portion of the housing 21 contains a central recess 35 preferably of circular cross-section. This central recess 15 contains a flexible compressible washer 30 and the disc 26 having a hole 27 of the requisite diameter. The disc 26 and washer 30 are held in position in the central recess 35 by means of a plate 31 having a central hole 36 which is of larger diameter than the hole 27 in the disc 26. The plate 31 contains three holes 33 which correspond to holes 34 in the bottom flange 37 of the housing 21, and the plate 31 is attached to the housing 21 by means of bolts and nuts 32 which pass through the respective holes 33 and 34. Alignment of the jet of printing liquid which issues from the hole 27 in the disc 26 when printing liquid is fed from the manifold into the central hole 22 is achieved by adjustment of one or more of the bolts and nuts 32. In place of the bolts and nuts 32 there can be used bolts which fit into threaded holes in the housing 21.
The plate 31 can be circular in shape. However in view of the close proximity of the printing guns in a row to each other thus limiting the overall size of each of the plates 31 it is often advantageous to have such plates of triangular cross-section, the said plates being arranged alternatively as depicted in FIG. IV which represents a view from underneath of a number of nozzles in a row.
This particular form of the apparatus comprises a housing 41 which is attached to a manifold (not shown). Attached to the underneath of the housing 41 are a number of plates 31 of triangular shape each of which is attached to the housing by three bolts and nuts 32. Each plate 31 contains a central hole 36 which are all situated in a line running the full length of the housing 41. Positioned between each plate 31 and the housing 41 is a disc 26 having a hole 27 and a soft washer (not shown), the discs being so positioned that each of the holes 27 is in the centre of a hole 36 and the holes 27 are also situated in a line running the full length of the housing 41.
In operation printing liquid supplied via the manifold issues in jets from each of the holes 27 and alignment of these jets is achieved by adjusting one or more of the bolts and nuts 32 in each plate 31.
It is preferred that each disc comprises a jewel, such as a synthetic sapphire, having a hole of the requisite diameter. The said holes can be cylindrical, but preferably are funnel shaped (in vertical cross section) so that the printing liquid enters from the wider side of the hole and emerges from the narrow side (as depicted in FIG. III). Such a form of hole in the disc leads to much more uniform jets.
The printing guns of the present invention are used in place of the printing guns described in Belgian Patent Specifications Nos. 771,808 and 801,757, the resulting apparatus being operated in the manner previously described.