METHOD FOR XEROGRAPHIC PRINTING OF A TEXTILE MATERIAL

Abstract: In a method for printing a textile material (5) or the like xerographically, a pattern is formed by means of a computer aided design system (CAD), said pattern is transferred onto a radiation-sensitive printing surface (4) of a xerographic textile printing machine, and the printing is carried out using said surface.

Description: I Method for xerographic printing of a textile material The invention relates to a method for printing of textiles, being disclosed by the preamble of claim 1. When creating designs for printing textiles, up to now in most cases the designer or artist has created an image of the design on some support, which is suitable for creating the design, as a rule on a paper. From the paper image the different colour components are separated into separate images on some medium, such as a film using a colour separation method. From the medium, the images of different colours are transferred onto a printing plate or cylinder, e.g. of metal or plastics, for letterpress or gravure printing respectively, or on a finely meshed screen for screen printing. Almost each of these stages are carried out in a time consuming multistage manual work. The printing processes of textiles require also large series for achieving a uniform quality and a desired control. In the domain of textiles the fast changing fashion makes great and ever increasing demands on fashion design and manufacturing of designs. This has been the reason for developing computer aided methods for creating fashion designs and for colour separation. The computer technique has not, however, been of effective assistance to textile printing itself in order to facilitate or to speed up preparing of printing cylinders or . plates, but the preparations for textile printing are still carried out largely manually. Moreover, the print processes in use require still large series. The use of the xerographic printing method has been increased sharply in the printing of paper due to its excellent flexibility. The method makes it possible to multiplicate an image immediately without any intermediate stages. In addition, the method is energy- consuming and environmentally acceptable. In the xerographic printing methods an image is transferred from an original object onto a light- sensitive printing surface either directly optically through a lens system or by means of a laser beam scanning the surface. In the last mentioned case the movements and the intensity of laser beam is controlled by computer according to the signal from the image. Xerographic printing can be carried out both as a multicolour and a single colour printing. In a multicolour printing the colour separation is usually carried out in the same machine as the very printing. The multicolour printing can be carried out either using single printing cylinder, in which event all colours are printed one after the other with the same cylinder, or using a specific cylinder for each of the colours. Up to now xerographic printing has been mainly used for printing paper. If the printing of textiles could utilize the several advantages of xerography, it could have many economical and productional benefits. The printing of textiles by means of a xerographic method differs from a corresponding paper printing process in some respects. E.g. the surface texture of textiles clearly differs from that of paper, and the same applies to their strength and softness properties as well as dimensional stability. For this reason various different methods for xerographic printing of textiles have been developed. The objects of the development have been direct printing on the surface of textiles- printing by means of heat transfer method, dyestuffs- as well as pretreatment of fabrics. Canon discloses in Japanese Published Patent Application 53-30339 a method, where a fabric is printed electrostatically and the dye is thereafter fixed and steamed. Kanebo discloses in British Patent 1,503,929 a method, where fabric is printed directly electrostatically. Xerox Corporation discloses in US Patent 4,064,285 a method, where a colour is transferred on the surface of fabric using a flexible plate. In British Patent 1,273,814 Canon discloses a method, where a fabric is printed in a multicolour process in an apparatus having one printing unit for each colour. In Japanese Published Patent Application 52-60627 Canon discloses a method, where an image is first xerographically created on a paper and it is thereafter transferred on the surface of a fabric using heat. Xerox uses a polymeric film as the medium according to British Patents 1,568,226 and 1,570,201. In Japanese Published Patent Application 52-60296 Canon discloses a method for improving the triboelectric properties of a fabric by means of a flushable polymer and in US-Patent 4,302,201 the same enterprise discloses a method, where two different dye-stuffs having a particle size of 5 to 50 μm are combined. Kanebo discloses in German Patent 2,006,749 dyestuffs containing a triazine derivative as a controlling substance and the same enterprise discloses in British Patent 1,503,929 the treatment of a fabric with a treating substance for regulating the resistivity of the fabric. Up to now, however, there has not been available such method that would make it possible to design and print textile desingε simultaneously. The aim of the invention is to provide a method, which avoids time consuming preliminary preparations for a printing process and the designed pattern can be immediately printed onto a textile material. The method of such kind is mainly characterised by the features disclosed in the characterising portion of claim 1. By means of a computer aided design system (CAD) a pattern, which may also be a multicolour pattern, is designed using all possibilities afforded by the designing system. The pattern can thereafter be in many ways transferred to a radiation-sensitive printing surface of a xerographic textile printing machine, and the printing is effected by means of this surface. Hence, the preliminary preparations between the designing work and the printing process are cut off considerably, and machine printing operations can be carried out on the actual textile material during the computer aided design. The appended subclaims disclose some advantageous alternatives of the method of the invention. Thus, using a CAD-system it is possible to create an auxiliary pattern, which is optically transferred by means of a lense system on the printing surface of a xerographic textile printing machine. It is also possible to transfer the pattern directly in a matrise form as a data transmission signal electrically or fiberoptically from the computer of the CAD-system, e.g. from its main memory, onto the printing surface of a xerographic textile printing machine without any separate intermediate or auxiliary patterns, in which event the radiation-sensitive printing surface of the xerographic textile printing machine is scanned with a beam activating the surface, the beam being controlled by means of a data transmission signal, which is in conformity with the pattern in the screen of the CAD-system. This activating beam may be a laser beam, and the pattern from the CAD-system to a device controlling the laser beam can be transferred in digital form in this case. The colour separation for a multicolour printing of textiles can be also effected using the CAD-system. The invention will be described in more detail in the following with references to the accompanying drawings, wherein Fig. 1 illustrates the method according to the invention using a direct data transmission of the pattern, Fig. 2 illustrates a method of the invention where a separate auxiliary pattern is formed and the image is transferred to a xerographic textile printing machine with the help of this pattern, Fig. 3 illustrates a method according to the invention, where an image is transferred in a direct data transmission to a xerographic textile printing machine, where a separate auxiliary pattern is formed, Fig. 4 illustrates a method according to the invention, where an image is transferred in a direct data transmission to a xerographic textile printing machine, where the image is formed on a radiation- sensitive printing surface without an auxiliary pattern, Fig. 5 illustrates a method according to Fig. 3, applied to multicolour printing with several cylinders and Fig. 6 illustrates a method according to Fig. 4, applied to multicolour printing with several cylinders. It is possible to realise the printing process of textiles in such a fashion that it is possible to pass directly from the computerised image forming stage to the printing process. Hence, the stages requiring time and manual work, such as colour separation and the preparation of printing plates or cylinders (patterns) can be completely avoided. This speeds up the starting and finishing of a printing process substantially and decreases the size of the series required, thus affording considerable economical advantages and shortening the time of delivery. The invention is carried out by controlling a xerographic textile printing device by means of a computer aided design system. The control can be carried out using one of the following main principles: - an image is formed on a solid support by means of a computer aided design system, on a paper for example, and said image is thereafter used as a pattern in a xerographic textile printing device (hard copy method, Fig. 2) or an image of a design is transferred from a computer aided design system in a direct data transmission onto an image surface of a xerographic printing machine, onto a picture tube for example, and said image on the picture tube is used as a pattern in a xerographic printing process (picture tube method, Figs. 3 and 5) , or an image formed by means of a computer aided design system is transferred without auxiliary or intermediate patterns in a direct data transmission into a xerographic printing machine, which itself develops and prints said image on a fabric (direct transmission method, Figs. 4 and 6). In a direct transmission method an image is formed in a xerographic printing device itself, and the formation is controlled by an electric of fiberoptic data transmission. As a matter of fact, a xeroprinting device can serve as a part of a design system, in which event a designer sees his design at once as finished, printed product. Xerographic printing machines operating on the basis of a laser beam can be used in a direct transmission method. Fig. 1 shows the main principle of the method according to the invention. A computer of a CAD-system is denoted with reference numeral 1 and auxiliary means of the CAD-system, keyboard and screen, are denoted with reference numeral 2. With the help of the CAD- system, a pattern depicting a textile design can be created on the screen 2 and it can be amended and its colours can be changed within the possibilities afforded by the system. The designed image can be also stored in a mass storage in data form, e.g. in a cassette, in a storage disk etc. The storage can be effected in digital form. As there is the intention to print the designed image on a fabric, it is transferred to a xerographic textile printing machine, which comprises a radiation-sensitive printing surface 4 operating on electrostatic principle. The pattern for printing is formed on this surface. In the example shown by the Figure, the printing surface is a rotating cylinder. A fabric 5 to be printed is guided into a direct or indirect (i.e. sufficient for printing technique) contact with the printing surface 4, whereafter the printed fabric 6 can be aftertreated, for example fixing, in known manners. Fig. 2 shows a hard copy method, where a pattern is formed by means of the CAD-system 1-2 on a solid support 8, e.g. on a paper using a printer or plotter 10. The support 8 is transferred to a xerographic textile printing machine, wherein it is transferred by means of an optical system having a source of light and lenses - onto a light-sensitive printing surface 4 and printing is effected in the same way as described hereinabove. The light source is denoted with reference numeral 20 and the lense system is denoted with reference numeral 9 in Fig. 2. Fig. 3 shows a picture tube method, where the pattern is transferred from the CAD-device 1, 2 in a data transmission directly onto an image surface 11 in a xerographic printing machine, in the case shown by the Figure onto the image surface of a usual picture tube. The auxiliary pattern formed thereon is transferred through an optical lens system 9 onto a radiation-sensitive printing surface Λ and the printing is performed as described hereinabove. Fig. 4 shows the direct transmission method, where an image is transferred from the CAD-device 1, 2 in a direct data transmissionelectricallyor fiberoptically to a xerographic textile printing machine. The signals are transmitted to a device 7 controlling an activating beam scanning a radiation-sensitive printing surface 4, the beam being preferably a laser beam, and an electrostatic pattern is formed on the printing surface 4 by means of the beam. The signals controlling the laser beam are transferred to the device 7 preferably in digital form. The transmission can take place in serial form or in parallel form. The xerographic textile printing machine may be operated with a single radiation-sensitive printing surface 4, e.g. a cylinder, in which case the fabric must be subjected to the effect of the surface at least as many times as is the number of basic colours in the printing. Another alternative of a printing machine is a combination according to Figs. 5 and 6, consisting of several xerographic printing stages, each of them printing one colour. The radiation-sensitive cylinder of each printing unit must be exposed separately to its specific colour. The number of printing units is in this case at least equal to the number of basic colours. In the hard copy method applied to a multicolour printing it is possible to produce an image with the computer aided method without a colour separation, in other words a usual multicolour image, and the task of colour separation is allotted to a xerographic textile printing machine, provided that it contains the appropriate equipment. On the other hand, the task of colour separation can be executed by the computer aided design equipment, e.g. so, that it prepares one single image for each colour and these images are used as the pattern for controlling the xeroprinting stage when the printing is effected colour by colour. In the picture tube method applied to multicolour printing the radiation-sensitive surface 4 of the xerographic printing machine is exposed to the multicolour image by means of the image surface 11 and the lens optics 9, either using one colour at a time or by all colours simultaneously. As the exposure is done by one colour at a time, the colour separation is carried out in the computer aided design equipment, and in this case every colour has its own printing stage comprising a radiation-sensitive cylinder 4 and an image surface 11, to which it is exposed (Fig. 5). As the exposure is done with all colours simultaneously, a colour separation is not needed in the computer aided design equipment . . The image and the position of the light-sensitive surface under exposure, as well as their movements with respect to each other, can be coordinated either optically, mechanically or electronically or using the combinations of these methods. As the direct transmission method is applied to multicolour printing, the data of the image in the computer aided design equipment is supplied to a xerographic printing machine in colour-separated form. The patterns resulting from the colour separation are preferably transferred in digital form, and in this event each pattern containing a determined colour is fed to its respective printing stage comprising a radiation-sensitive cylinder 4 scanned by a laser beam. In multicolour printing it is also possible to use the same radiation-sensitive cylinder, through which each colour is in turn transferred onto the fabric, in other words the fabric is guided via the cylinder so many times as is the number of colours in the printing process. As the pattern signals are transferred directly either using the direct transmission method or picture tube method, a device 3 controlling the xerographic printing machine is situated between the CAD-equipment 1, 2 and the xerographic printing machine. The device converts the image signals from the CAD-equipment into a form compatible with the xerographic printing machine and it gives the control commands to the printing machines, as shown in Figs. 1 and 4. An example for realising this alternative of the invention is shown in Fig. 6 more closely. The control device 3 comprises a control computer 10, digital-to- analog converters 11 and a control unit 12 of the printing machine. From the CAD-station 1- 2 the image is transferred in a known manner in digital form to the control computer 10 having a video memory. From the video memory a colour signal, corresponding to one colour, is transferred each through its respective line R, G or B through the D/A converter 11 in a known manner to laser guns 7, being also arranged one for each colour. Laser beams 18 are transferred by means of rotating polygonal mirrors 14 onto a light-sensitive printing cylinder 4 in a known manner, the rotating mirror 14 effecting the scanning. The mirror is driven by a motor 15. One mirror and one printing cylinder is provided for each colour. Synchronizing pulses known in video technique are transmitted through line T to the video memory/computer unit 10 from the control computer 12 of the xerographic printing unit, which computer controls the motors of the rotating mirrors and through a power transformer 16 it controls the driving motor 17 of the printing machine. The speed of the printing machine is controlled by means of an adjusting knob 19 and the required delays in laser signals between the different colours for a proper coordination of the colours in the finished printed picture 6 are controlled through the control computer 12 of the xerographic printing machine. Other well-known methods for transferring a data transmission signal directly to a xerographic printing machine can be used as well for printing a CAD-designed image with the aid of a xerographic method. The invention is not exclusively restricted to the embodiments shown in the Figures, but it can be modified within the scope of the inventional idea represented by the claims. In the very printing process, some of the xerographic printing methods disclosed by the aforementioned patents and patent applications can be used, the term "xerographic" bearing in this context the meaning of a printing, which is carried out by means of an electrostatic image forming and a dyestuff. The printing inks can be in this case either dry or liquid. It is to be understood, that the transmission of an image to a xerographic textile printing machine comprises also a transmission by optical fibers, the principle of this method being similar to an electric transmission. The method can be used, when it is desirable to view during the design the appearance of a finished, printed pattern on the surface of the textile material. The invention opens also new prospects for shifting from large series to more individual designs, the printing of which can be carried out in a short time and the customer can at the same time make comparisons between different alternatives by changing the pattern, e.g. interchanging colours, using possibilities afforded by CAD-technique.

Claims: Claims ; 1. Method for xerographic printing of a textile material (5), characterised in that a pattern is created by means of a computer aided design system (CAD), the pattern being transferred onto a radiation- sensitive printing surface (4) of a xerographic textile printing machine, and the printing is carried out using said surface. 2. Method as claimed in claim 1, characterised in that the pattern is transferred to the xerographic textile printing machine directly in a data transmission signal. 3. Method as claimed in claim 1, characterised in that the pattern is created by means of the computer aided design system, an auxiliary pattern (8, 11) is formed of said pattern, and the pattern is transferred onto the radiation-sensitive printing surface (4) of the xerographic textile printing machine by means of said auxiliary pattern, and the printing is carried out using said surface. 4. Method as claimed in claim 3, characterised in that the auxiliary pattern is formed on a solid support (8), the solid support is transferred to the xerographic textile printing machine, wherein the auxiliary pattern on the support is transferred by means of a lens optics (9) onto the radiation- sensitive printing surface (4) of the xerographic textile printing machine, and the printing is carried out using said surface. 5. Method as claimed in claim 2, characterised in that the pattern is created by means of the computer aided design system (CAD), said pattern is transferred through a data transmission signal without an auxiliary pattern onto the radiation-sensitive printing surface (4) of the xerographic textile printing machine, and the printing is carried out using said surface. 6. Method as claimed in claims 2 and 3, characterised in that the pattern is transferred through the data transmission signal to the xerographic textile printing machine onto an image surface (11), whereon said auxialiary pattern is formed, which is transferred by means of a lens optics (9) onto the radiation-sensitive printing surface (4) of the xerographic textile printing machine, and the printing is carried out using said surface. 7. Method as claimed in claim 5, characterised in that the pattern is transferred to the radiation- sensitive printing surface (4) of the xerographic textile printing machine by scanning it with an activating beam, which is controlled (7) by means of the data transmission signal, which is in conformity with said pattern. 8. Method as claimed in claim 7, characterised in that the activating beam is a laser beam. 9. Method as claimed in any of preceding claims 5 to 8, characterised in that the pattern is transferred to the xerographic textile printing machine in digital form. 10. Method as claimed in any of preceding claims for multicolour printing, characterised in that the colour separation is carried out by means of the computer aided design system (CAD), which creates one separate pattern for each colour. 11. Method as claimed in claims 9 and 10, characterised in that the patterns obtained by means of the colour separation are transferred in digital form. 12. Method as claimed in any of preceding claims 1 to 9, characterised in that the colour separation is carried out in the xerographic textile printing machine.

Inventors: EPSTEIN MIKAEL, MALMSTROEM BEN, EPSTEIN, MIKAEL, MALMSTROEM, BEN
Applicants: VALTION TEKNILLINEN, VALTION TEKNILLINEN TUTKIMUSKESKUS
Application year: 1989
Main classification: B41J3
IPC codes: B41J3, B41M1, D06P1, D06P5, G03G15, G06K15