INK SUPPLY MEANS FOR A PRINTING MACHINE

Abstract: An ink supply unit (10) for a receiving roller (11) of a printing machine comprises an ink rail (12) mounted in close proximity to the surface of the receiving roller (11). A plurality of ink reservoirs (17) are mounted one above the other in the ink rail (12) and discharge differently coloured inks in accordance with the requirements onto the surface of the receiving roller (11) through a valve mechanism (18). Wiper rollers (14) are mounted adjacent to the surface of the receiving roller (11) to wipe the surface thereof to reduce ink wastage due to misting or the like. In use, the inks are introduced onto the surface of the receiving roller (11) and are mixed to form the required colour for printing by the combined action of the wiper rollers (14) and a roller train which links the receiving roller (11) and the print roller in a printing machine.

Description: INK SUPPLY MEANS FOR A PRINTING MACHINE This invention relates to improvements in or relating to ink supply means for a printing machine and more particularly to an ink supply means which is capable of supplying at least three primary coloured inks to a print roller surface in such a manner that they are mixed on the roller surface to form a desired colour of ink for printing. Conventionally, ink supply means in a printing machine are arranged so as to supply a single colour of ink to a print roller. If it is desired to change the colour of ink for printing, usually the machine has to be stopped, the ink supply changed and the printing roller cleaned. Of course, this procedure is time consuming and because the printing machine is stopped, printing time is increased. Furthermore, since it is not possible to change ink colour without the necessity for the above actions to be taken, printing versatility is restricted. It is an object of the present invention to provide a more versatile ink supply means wherein at least two different coloured inks, particularly two or three primary colours, can be supplied in predetermined relative quantities for mixing prior to application to the surface of the print roller to give any desired colour. According to the present invention therefore there is provided an ink supply means for a printing machine comprising an ink rail mounted so as to extend generally longitudinally of a receiving roller of the machine, wiper rollers mounted adjacent a surface of the receiving roller to wipe a surface thereof, said ink rail comprising at least two discrete ink storage means connected to respective ink outlets in a face of said rail adjacent a surface of the receiving roller and valve means associated with each said outlet to regulate flow of ink through each said outlet, said receiving roller being linked to a print roller via a roller train, said inks being mixed by the action of said wiper rollers and passage of the ink between rollers of said roller train. With this arrangement it is possible to provide an ink supply means which is more versatile in use, and which gives rise to an increased number of printing possibilities. Preferably said ink rail has a generally curved end face thereto which, in use, is mounted in close proximity to the surface of the receiving roller and generally conforms to the outer circumferential surface of the roller in order to reduce ink wastage. Preferably said ink storage means are disposed one above the other in said ink rail in order to best utilise the available space in the rail. Preferably supply of ink from each reservoir through each respective outlet is controller by a solenoid operated valve means under the control of a central control unit. Said central control unit may be microprocessor based. Preferably three ink storage means are provided, respective ones of which stores inks coloured in the three primary colours, namely Cyan, Magenta, Yellow. The invention will now be described further by way of example only and with reference to the accompanying drawings of which:- Fig. 1 shows a diagrammatic side view of one form of ink supply means according to the present invention; and Fig. 2 shows a diagrammatic plan view of a conventional printing machine incorporating the ink supply means of Fig. 1. Referring now to Fig. 1 , there is shown an ink supply unit 10 for a receiving roller 1 1 of a printing machine. The ink supply unit 10 comprises an ink rail 12 having a generally concave end face 17 thereto which conforms generally with the outer circumferential surface of the receiving roller 1 1. The ink rail 12 is mounted in close proximity to the surface of the receiving roller 1 1 with a gap of 0.002-0.012" (0.00508-0.03048mm) therebetween in order to prevent ink wastage. Wiper rollers 14 of the kind described in my co-pending UK Application No. 931 1230.8 are mounted at top and bottom of the ink rail 12 adjacent the concave surface 13 and are disposed such that the outer circumferential surface 16 of each roller 14 is spaced by 0.004-0.010" (0.01016-0.0254mm) from the outer surface of the receiving roller 1 1. The wiper rollers 14 act to further reduce ink wastage by ensuring a uniform layer of ink is formed on the outer surface of the roller 1 1 thereby preventing misting and also assists in the mixing of the inks applied to the surface of the roller 1 1 . Ink reservoirs 17 are provided on the ink rail 12 and which extend substantially the entire longitudinal length thereof. In the embodiment shown in the drawings three such reservoirs 17 are shown mounted one above the other, however it will be appreciated that as many ink reservoirs can be provided as desired or as necessary, the number only being limited by any restriction on the dimensions of the ink rail 12. Each ink reservoir 17 has associated therewith a solenoid operated valve mechanism 18 which controls flow of ink from the reservoir 17 through a feed passage 19 to an outlet 21 adjacent the surface of the receiving roller 11. Each valve mechanism 18 comprises a valve head 22 mounted on a shaft 23 which is movable away from the roller 1 1 against the resistance of a biassing spring 24. The shaft 23 extends through the interior of an electromagnet 26 such that upon actuation of the electromagnet 26, the shaft 23 moves away from the roller 1 1 against the bias of the biassing spring 24 moving the valve head 22 away from the respective feed passage 19, thereby allowing ink to flow from the reservoir 17 to the surface of the roller 1 1. The actuation of the electromagnet 26 can be under the control of a central control unit (not shown) which may be microprocessor based and thus the supply of ink from the reservoirs 17 to the surface of the roller 1 1 can be controller very accurately. Figure 2 shows a schematic representation of the layout of a typical printing machine, for example as used in the newspaper industry. An ink supply unit 10 of Fig. 1 is mounted adjacent a receiving roller which is linked to a print roller 27 by a respective roller train 28. The print rollers 27 are mounted in close proximity to a paper mounting roller 29. The path of the paper through the printing machine is indicated by arrow X and as the paper passes round the mounting roller 29 the ink is applied to the paper by each print roller 27. In a conventional printing machine, each print roller would apply a single colour ink only to the paper (chosen usually from Cyan, Magenta or Yellow), however with the present arrangement the colour of ink to be applied to the paper by each print roller can be changed easily and quickly in a manner to be described hereinafter. The ink supply unit 10 associated with each receiving roller 1 1 can, as described above, under the control of a central control unit (not shown), apply any predetermined quantities of the inks contained in the reservoirs 17 to the surface of the receiving roller 1 1. In the present embodiment of the three primary colours (Cyan, Magenta and Yellow) are contained in three reservoirs, however of course any number of reservoirs can be provided as desired or as appropriate. Thus, for example, one or more additional reservoirs can be provided which can contain one or more additional colours, for example Black, Gold, Silver, etc. Thus, under the control of the control unit, predetermined quantities of ink for each reservoir are applied to the surface of each roller 11. The mixing of the different coloured inks to form the ink of the desired colour is initiated by the action of wiper rollers 14. As described in my co-pending application described above, these rollers are driven so that the circumferential surfaces move in a direction opposite to the surface of the roller 1 1 and therefore act to wipe the sur ace of the roller. Therefore the inks applied to the surface of the roller 1 1 in the vicinity of outlet 21 are mixed as a fine uniform layer of ink is formed on the surface of the roller 1 1 under the action of the wiper rollers 14. Mixing of the inks is continued as the ink passes down each roller train 28 from the roller 1 1 to each print roller 29. The transfer of ink between each roller of the train ensures that the mixing of the inks is thorough by the time the inks are transferred to the print roller 27 for application to the paper during printing. It is of course to be appreciated that using a conventional printing machine of the type shown in Fig. 2 and with each ink supply unit 10 being controller by the control unit independently of all the other supply units, the printing possibilities are increased significantly and therefore the versatility is increased. Thus for example, each ink supply unit 10 can supply a different mixed colour ink, or alternatively each ink supply unit can supply the identical single colour ink. Furthermore, many variations on this are permitted and will be readily appreciated by the skilled reader. It is of course to be understood that the invention is not intended to be restricted to the details of the above embodiment which are described by way of example only.

Claims: CLAIMS 1. Ink supply means for a printing machine comprising an ink rail mounted so as to extend generally longitudinally of a receiving roller of the machine, wiper rollers mounted adjacent a surface of the receiving roller to wipe a surface thereof, said ink rail comprising at least two discrete ink storage means connected to respective ink outlets in a face of said rail adjacent a surface of the receiving roller and valve means associated with each said outlet to regulate flow of ink through each said outlet, said receiving roller being linked to a print roller via a roller train, said inks being mixed by the action of said wiper rollers and passage of the ink between rollers of said roller train. 2. Ink supply means according to claim 1 wherein said ink rail has a generally curved end face thereto which, in use, is mounted in close proximity to the surface of the receiving roller and generally conforms to the outer circumferential surface of the roller in order to reduce ink wastage. 3. Ink supply means according to claim 1 or claim 2 wherein said ink storage means are disposed one above the other in said ink rail in order to best utilise the available space in the rail. 4. Ink supply means according to any one of claims 1 to 3 wherein the supply of ink from each reservoir through each respective outlet is controlled by a solenoid operated valve under the control of a central control unit. 5. Ink supply means according to claim 4 wherein the central control unit is microprocessor based. 6. Ink supply means according to any one of claims 1 to 5 wherein three ink storage means are provided, respective ones of which store inks respectively coloured in the three primary colours, namely Cyan, Magenta, Yellow. 7. Ink supply means substantially as hereinbefore described with reference to the accompanying drawings. 8. A printing machine incorporating an ink supply means according to any preceding claim. 9. A printing machine substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.

Inventors: MCMANAMON DAVID EDWARD, MCMANAMON, DAVID, EDWARD
Applicants: MCMANAMON DAVID EDWARD, MCMANAMON, DAVID, EDWARD
Application year: 1995
Main classification: B41F31
IPC codes: B41F31