AU586990C - Method of and apparatus for applying images to a surface - Google Patents

Description

"METHOD OF AND APPARATUS FOR APPLYING IMAGES TO A SURFACE"

This invention relates to a method of and apparatus for applying images to a surface.

In particular this invention relates to the application of large images such as for advertising signs and the like. However it is not limited to such applications. For example it may be used for producing silk screen positives or for applying images to textile or like flexible materials. It may also be used for producing small images if desired.

In the advertising industry large amounts of money are spent on the production of street and building fascia signs and the like and at present these are formed as either a one off hand painted image or in multiples by a silk screen printing process. A one off hand painted sign is expensive to produce and the degree of accuracy of reproduction from a master depends on the skill of the artist. Multiple signs produced by a silk screen printing process may be economical to produce in large numbers. However the lead time for production may be several days as silk screen printing requires production and use of photograpic positives including four colour separation positives, negatives, hand cut and photographic stencils and block out material. The silk screen so produced has a limited life and a separate screen is required for each colour run. Modern technology has enabled temporary images such as television screen images to be modified by electronically modifying the signal from which the image is produced. For example, images can be modified by changes in colours, by addition or substruction of selected features, by distortion of the image or by the use of half tone or other tonal modifications. while these temporary images can be photographed to provide a permanent modified image, it is not practical or economical to use conventional photography to produce large signs or other large images. Thus even though a master image of a sign may be prepa red with the assistance of electronic processing apparatus traditional reproduction techniques such as described above have to be utilized to produce the desired large image.

The present invention aims to provide a method of and apparatus for applying images to a surface which will alleviate the abovementioned and other disadvantages associated with the presently available methods and which will be reliable and efficient in use. Other objects and advantages of this invention will hereinafter become apparent.

With the foregoing and other objects in view, this invention in one aspect resides broadly in an applicator for applying a material to a surface and including storage means for the material; an outlet from the storage means from which the material may pass onto the surface and actuating means for controlling passage of material from said outlet. The storage means may be a dispenser for particulate material but preferably the material to be applied is a fluent material and the storage means is a chamber for the fluent material. The actuating means may oe adapted to pump fluent material through saia outlet or alternatively the chamber may be pressurized to force fluent material through the outlet and the actuating means may comprise control valve means associated with said outlet. In the latter application the actuating means may include a valve member mounted for movement between an open an closed position in relation to said outlet and an actuator for moving the valve means.

The actuator may oe for example a hydraulic, pneumatic or mechanical actuator or the like or it may be in the form of a magnet such as an electro magnet adapted, to be activated upon command to move the valve member from the outlet to enable the fluent material to flow therethrough. For this purpose a valve member for controlling flow through said outlet may be associated with a control, member formed of material adapted for magnetic attraction to and/or magnetic repulsion by the electro magnet whereby the latter may be acutated for moving the valve member to and from said outlet. For this purpose the control member may be in the form of a follower associated with the electro magnet and preferably the core of the electro magnet and the follower are formed from a low hysteresis magnetic material and the coil of the electro magnet may be a low inductance coil to facilitate high speed repetitive actuation of the applicator. The follower may be guided for reciprocal movement to enable the valve member to be moved towards or away from the outlet or alternatively the follower could be a pivotable member adapted to guide the valve member to and from the outlet. The valve member could be biased towards the closed position such as by a spring or by repulsion from the electro magnet and adepted to be lifted from the outlet to enable fluent material to flow therethrough upon change of state of the electro magnet. The polarity of the electro magnet could be reversible to open and close the outlet. The electro magnet may have separate coiIs for acutation in its respective opposite modes.

The applicator may be supported for controlled movement relative to the surface on which the image is to be formed. For example the applicator may be supported on the carrier of an X Y plotter for selected movement relative to the surface and it may be comouter controlled to apply fluent material at selected co-ordinates whereby an image may be applied to the surface. If desired a plurality of applicators may be supported on the carrier and each applicator may be associated with a respective base colour and be computer controlled so that a colour image may be applied to the surface. Preferably the amount of fluent material applied at each command is selectiveIy controllable whereby a colour image may be applied to the surface in the form of a plurality of discreet dots formed in a matrix arrangement to provide the required image. For this purpope the fluent material in the chamber is under pressure and the amount of material applied is controlled by the duration of opening of the outlet. The colours may pe applied so as to blend into one another or colours may be overprinted to form a continuous tone or part tone image. The electro magnet may pe associated with a decoder adapted to decode encoded signal from an electronic colour separation scanner or from a computer or the like signal generation or transmission means.

In a preferred form a plurality of applicators associated with respective base colours are controlled by a n encoder associated with a digital four colour separation scanner associated with computing means whereby the image signal may be modified before transmission to the decoder. For example the signal may be modified to vary dimensions, colour and to provide adjustments and image alterations as well as to insert additional extra material. Such modifications may be completed by using a keyboard associated with a visual display unit connected to a computer. Preferably the visual display unit is associated with a non-volatile data storage unit so that the original image can be stored and modified for transmission to the decoder associated with the applicators.

The fluent material may be a liquid, powder, paste or jelly or a fibrous material such as flock or ink stain or paint and the latter may be adapted to set only after application and suitably by the application of a suitable catalyst or the like to the surface after the i mage has been app l i ed thereto . As ment i oned relatively large quantities of liquid may be applied so that adjacent applications of fluent material bleed into one another or large quantities of a relatively thick paste or the like may be applied to provide a textured

In another aspect this invention resides broadly in a method of forming an image, the method comprising providing an electronic signal corresponding to an image to be reproduced encoding the electronic signal, transmitting the encoded signal to a decoder associated with a plurality of applicators adapted to move in a controlled path across a surface to apply respective base colours to a surface whereby the applicator may be moved relative to the surface controlled by the computing means to enable the desired image to be applied to the surface.

The encoded signal may be fed to a storage unit associated with a video display unit having a keyboard whereby the image may be readily modified to form a further electronic signal of the modified image, the method further including encoding a modified signal and transmitting that modified signal to the decoding means which controls the applicators.

In order that this invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a typical embodiment of the present invention and wherein:-

FIG 1 is a perspective view of one form of image forming apparatus made in accordance with the present invention;

FIG 2 is a flow sheet illustrating the image forming apparatus and its associated control means;

FIG 3 illustrates one form of applicator head;

FIG 4 is a cross sectional view taken along the tines of 4-4 of FIG 3;

FIG 5 is a cross sectional view taken along the line

5-5 of FIG 3.;

FIG 6, 7 and 8 illustrate the frame components of the applicator head;

FIG 9 is an entdrged view of one applicator assembly.

The image forming apparatus 10 illustrated in FIG 1 and FIG 2 utilizes an applicator head 11 associated with an XY plotter assembly 12 adapted for connection to suitable control means via the interface connection 13. The XY plotter assembly 12 includes a platen 14 in which a central drive roller 15 is mounted for rotation for moving a sheet like panel (not shown) which may be flexible or rigid and on which an image is to be formed, in the X direction past the applicator head 11 in a controlled manner. Traction wheels 16 are provided at each end of the roller 15 to maintain the panel in contact with the roller 15 for accurate movement therewith. The applicator head 11 is supported by linear bearings 17 on a pair of spaced guide rails 18 which extend between end housings 19 and 20 at opposite ends of the platen 14. The end housing 19 supports a stepper motor 21 which advances the roller 15 in stepped rotational manner whereby the panel to be treated is advanced in fixed increments in the X direction, such as in increments of 2mm for example. A further stepper motor 22 drives the endless belt 23 which passes between the end housings 19 and 20 for reciprocal movement therebetween. The belt 23 connects to the applicator head 11 and the stepper motor 22 is adpated to advance the applicator head 11 across the platen 14 in the Y direction in fixed increments also of 2mm for example. The stepper motors 21 and 22 are connected to a switching control 24 associated with the computer 25 while the decoder in the applicator head 11 is controlled directly from the computer 25 whereby movement in the X Y direction and actuation of the applicator head may be co-ordinated. This arrangement is shown in FIG 2 and preferably the relative movement between the panel to be treated and the applicated is constant with the panel advancing incrementally after each pass of the applicator head across the panel to be treated.

The housing 20 supports reservoirs for the four base colours. These may be the primary colours namely yellow, red , blue and black, which are connected via the line 2ό to the applicator head 11 as well as the necessary heating and cooling means for conditioning the fluid in the reservoirs. The computer assembly is aiso supported within the end housing 20. The line 26 also carries the control wires for the decoding board 27 encapsulated within the upper body portion 28 of the applicator head 11.

Referring to FIG 3 to 9 it will be seen that the applicator head 11 includes the upper body portion 28 in which a plurality of electro magnets 29 are encapsulated together with the decoding board 27 connected via the edge connector 30 to the computer 25. The body portion 28 is cast about the electro magnets 29 and the decoding board 27 after the threaded core end projections 31 of the electro magnets 29 a re screwed into the threaded apertures in a supporting top plate 32. The encapsulating material is selected so as to dissipate heat from the electro magnets 29. The support plate 32 is adapted to be bolted to an apertured bottom plate 33 held in spaced relationship therewith and having an intermediate guide or baffle plate 34 sandwiched sealably between the top and bottom plates. The plates 32, 33 and 34 are formed of non magnetic material.

As can be seen in FIG 9 the protruding threaded portion 31 of the solenoid core extends through the top plate 32 and terminates in closely spaced relationship with a follower 35 supported for free reciprocal movement towards and away from the electro magnet 29. The follower 35 is associated with a coarsely tapered needle valve 36 which is adapted to engage sealably in the respective tapered outlet apertures 37 arranged in a grid pattern in the bottom plate 33. A return spring 38 is connected between a collar 39 on the follower 35 and the baffle plate 34 so as to urge the needle valve 3ό into the closed position relative to the outlet 37. The arrangement is such that upon energising the solenoid 29 a magnetic field is created in the core 31, which is formed of low hysteresis material, so that the follower 35 is attracted thereto and the needle valve 36 is lifted from the outlet aperture 37. Only a small lift is required to open the outlet 37. Accordingly high speed repetitive actuation of the needle valve 36 may be achieved and dot like deposits may be formed on a panel in controlled manner from the outlets 37. The electro magnet may be energised for any selected length of time so that the required amount of liquid which is deposited from the outlet 37. For this purpose the fluid chamber 40 formed between the upper and lower plates 32 and 33 is pressurised by suitable pumping means associated with the supply tines 26.

Thus the size of the dots so formed can be controlled by the computer by varying the length of time the electro magnets are energised. As illustrated in FIGS 6, 7 and 8, one longitudinal side of the plates 32, 33 and 34 are extended at 4ό to form an inlet for fluent material into the chamber 40. For this purpose the bottom plate is provided with feed channels 41 which communicate with inlets 42 provided on the top plate 32 and associated with mating apertures 43 and 44 in the top and baffle plates respectively.

As shown in FIGS 4 AND 5 the applicator head 11 is divided longitudinally into four sections by the dividing walls 45 whereby each section in use may be supplied with a respective base colour. Each section has an array of sixteen outlets 37 and associated electro magnets 29 and control valves arranged in a square grid pattern. The intermediate or baffle plate 34 is provided with flow apertures 47 (shown shaded) which permit free flow of fluent material between the upper and lower parts of each chamber 40 as well as guide apertures 48 for the followers 35.

Referring to FIG 2 it will be seen that the computer 25 which controls the X Y printer and the applicator head 11 may be associated with a digital four colour separation scanner 50 which may be adapted to convert images of a two or three dimensionat original 51 into a high resolution digital form signal which may be recorded by a non volatile storage unit 52 such as a floppy disc unit or the like or fed directly to the computer 25. Thus the recorded ddta may be filed for further use. The computer 25 is programmed to act on the above data and it is associated with a keyboard 53 and a video display unit 54 to enable the operator to insert and monitor further information such as dimensions, colour and image alterations, adjustments. The video display unit 54 allows the operator to view a portion or all of the image before proceeding with further steps so that appropriate changes can be made if required. A conventional printer plotter 55 may be used at this stage to make a physical copy of the image displayed on the video unit 54. The fluent material is stored in the reservoir 56 and pumped by pump 57 to the applicator 11.

When the operator is satisfied that all adjustments, alterations and the like are final the computer 25 is actuated to control and co-ordinate the XY plotter 12 via the switching controls 24 and the applicator head 11 whereby the computer 25 controls the location and quantity of fluent material applied to the panel to be treated.

Any pattern of movement of the applicator head relative to the panel to be treated may be accommodated by appropriate control of the applicator head by use of suitdble software for the computer 25. However in order to minimise loads and maximise speed of operation it is preferred that the applicator head be adapted to apply fluent material to the workpiece in series of lines across the workpiece while the latter remains stationery. The applicator head is adapted to apply fluent material in its passage in both directions across the workpiece and the position of the workpiece relative to the applicator head is advanced between each pass of the applicator head 11. This arrangement is provided without overprinting by controlling the number of movements of the applicator head and the distance between movements in accordance with the spacing of the apertures 37 in the X and Y directions.

For example if the image quality dictates that image dots have to be arranged at one unit spacings, where a unit may be one half millimetre for example and the outlets 27 are arranged an uneven number of units apart, such as 25 units, then the applicator head is adapted to advance in increments of four units in the Y direction whereby each outlet is capable of depositing six spaced dots before it passes beyond the initial position of the adjacent outlet 37. Subsequently all spaces on the workpiece at 1 unit intervals may be filled in in the one pass. That is the twenty four spaces between each adjacent pair of outlets 37 may be filled in with a set of six dots from each of the four apertures in each row of apertures 37.

As shown in FIG 10 each section of outlet apertures 27 in the applicator head 11 comprises four rows of outlets 37 in the Y direction and four rows of outlets 37 in the X direction. The sections are spaced along the X axis and the applicator head is advanced in the y direction. Thus on each pass of the applicator head groups of 4 rows of dots in the respective base colours may be deposited with the dots in each row deposited according to the information on the computer. Because the outlets 37 are arranged in a grid of 25 units square and because the applicator is advdnced in the X and Y directions in increments of 4 units, continuous operation of the motors will position the outlets at 1 un i t intervals over the workpiece without a need for hopping across a section cr backing and filling. Thus the stepper motors 2i and 22 may be driven continuously in their regulated intermittent motion so as to provide minimal strain on the drive train assembly and the motors. Furthermore additional software programming will not be required to ensure that overprinting is eliminated. Thus a colour dot may be placed at any position on the workpiece within a 1 unit tolerance. The colour may be a base colour or it may be modified by overprinting with another colour. In this manner four rows of dots of each of the four base colours may be deposited across the workpiece in each pass. The stepper motor 22 is then actuated to advance the workpiece and the applicator head 11 returns applying another four rows of dots of the respective base colours . In the manner as described above after twenty four incremental advancements, the rows of coloured dots will be deposited adjacent one another to provide the desired colour image. Of course the electro magnets controlled by the decoder board are adapted to actuate the outlets only in positions where the required base colour is required to achieve the image. If required only one colour may be applied to the applicator head and this may be programmed to print a single colour i mage such as words or an outline in one pass across the workpiece. Furthermore an image may not require a full pass of the applicator in the Y direction and the computer can control the WY plotter to return the applicator from any position across the plotter 14.

In use an original or master from which the image is to be obtained is photographed by the four colour separation scanner 50 which suitably separates the colour image into 4 colour component and the resultant combined signal is fed to the memory 52 or directly to the computer 25. This image is then modified as required by the keyboard and a temporary printout of the image is displayed on the associated video display unit 54 may be provided by the plotter printer 55. When the desired image is achieved the plotter printer 12 is actuated and the applicator head is controlled to deposit the base colour dots in the appropriate positions onto the workpiece which is coloured white to achieve the desired image. Of course the size of the image is determined by the width of the platen of the X Y plotter 12 but suitably this may be in the order of 2 or 5 metres and of course the panel to be printed can be any desired length. The XY plotter and its associated applicator head could be disposed at remote locations so that appropriate signals could be forwarded through the telephone system or the like from a central computer assembly. This may be used to control d number of such XY plotter printers at various different locations.

In the preferred embodiment of the invention the rails and applicator head are adjustable in the Y direction to accommodate different thickness workpieces and to enable the distance of the applicator head from the workpiece to be varied. This wilt vary the size of the dots applied.

If desired the head 11 may be increased in size by adding further similar heads. Any number can be arranged in end to end relationship or in side by side relationship as desired. Of course a single applicator could also be used. The applicator could be a single spray head for example and paint requiring further treatment to set could be used to prevent clogging of the applicator. For example the wet paint could be subsequently heated or chemically treated to cause it to set.

Of course the above has been given only by way of illustrative example of this invention and it will be realised that all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is defined in the appended claims.

Claims (15)

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:-

1. An applicator for applying a material to a surface and including storage means for the material; an outlet from the storage means from which the material may pass onto the surface and actuating means for controlling passage of material from said outlet,

2. An applicator according to Claim 1, wherein said material is a fluent material and said storage means is a chamber from which said material may be forced through said outlet.

3. An applicator according to Claim 2, wherein said chamber is adapted to be pressurized to force fluent material through said outlet and there is provided valve means associated with said outlet for controlling flow therethrough.

4. An applicator according to Claim 3, wherein said valve means is so made and arranged whereby its mass ιand its movement is relatively small so that it may be actuated repetitively at a relatively high rate of operation in reponse to a controlling signal.

5. An applicator according to Claim 4, wherein the actuating means for said valve means may be operated to hold the vdlve means released from said outlet for a selected length of time to control the amount of material forced through said outlet.

6. An applicator according to Claim 4 or Claim 5, wherein said actuating means includes an electro magnet and an associated follower adapted to be attracted and/or repelled by the electro magnet and connected to said valve means for moving the Latter between open and closed attitudes relative to said outlet.

7. An applicator according to any one of the preceding claims, wherein there are provided a plurality of said outlets and associated actuating means.

8. An applicator according to Claim 7, wherein said outlets are divided into a plurality of groups of outlets, each being associated with a respective chamber whereby a plurality of types or colours of fluent material may be applied to a surface.

9. Image forming apparatus including support means for guiding an applicator, as defined in any one of the preceding claims, for relative movement with respect to a workpiece whereby fluent material may be applied to selected areas of the workpiece from said applicator and control means for controlling discharge of fluent material from said applicator onto said workpiece.

10. An applicator according to any one of Claims 6 to 9, wherein said actuating means includes switching means for switching said electro magnets and decoding means for decoding the signal tramsmitted thereto.

11. Image forming apparatus according to Claim 9 or Claim 10, wherein said support means is an X Y plotter and said applicator is adapted to apply fluent material in the four primary colours to the workpiece.

12. Image forming apparatus according to Claim 10 or Claim 11, wherein said control means is computer means adapted to receive a signal from colour separation scanner.

13. Image forming apparatus according to Claim 12, wherein said computer means includes dn associated keyboard and a video display unit whereby the signal from said scanner may be modified displayed before transmission to said applicator.

14. A method of forming a painted image on a surface and comprising:- providing an electronic signal corresponding to an image to be formed; encoding the signal; transmitting the encloded signal to decoding means associated with an applicator assembly and co-ordinating movement of the applicator assembly relative to the surface with the actuating means of said pdint applicator assembly to produce the desired image.

15. A method according to Claim 14 and wherein said applicator is as defined in any one of Claims 1 to 10.

i6. Image forming apparatus substantially as hereinbefore described with reference to the accompanying drawings.