Coating Device for Coating an Elongated Substrate

Abstract

A device and system for dynamically applying liquid to a single thread for a thread consuming device as said thread moves relative to the device along a path of movement. The device is configured to apply liquid to said thread by means of an electrospraying unit. A method for applying liquid to a single thread for a thread consuming device as said thread moves relative to the device along a path of movement is also provided.

Description

FIELD OF THE INVENTION

The present invention relates coating of a thread and, more particularly, coating in form of dyeing said thread with a liquid, such as a liquid comprising ink.

BACKGROUND ART

Devices for embroidering a medium, such as cloth, in accordance with a design generated using a personal computer are known. Such devices are advantageous in that they make it easy to embroider a complex design.

However, the color of the embroidered design depends on the color of the thread. Therefore, when embroidering is carried out using different colored threads, the thread used in the apparatus must be changed each time a different color is to be embroidered. To change the thread, the thread currently in the apparatus must be cut and removed, and another thread having a different color must be threaded in the apparatus and passed through the hole of an embroidery needle. This slows down the embroidery operation and makes it more costly.

Embroidery devices for industrial use and sewing machines capable of embroidering are known. However, it is necessary to change an upper thread corresponding to the requested color, and it is necessary to design the embroidery pattern taking into account the limitations of the embroidery machine and available threads, and then to embroider with these available threads by exchanging the upper thread, as needed. Hence, a great deal of time and work is required to embroider in different colors using this technique. In addition, since many threads of various colors must be used, the colors are limited to the number of threads used, and therefore it is cumbersome to embroider in a large number of colors. For example, when embroidering in colors varying continuously from dark green to yellow, it is necessary to provide threads of numerous colors and change them in accordance with the desired color, and therefore the ability of such embroidery techniques to express color variations is limited.

In recent years, textile printing using ink jet printing techniques (Digital Textile Ink Jet Printing) has been put to practical use and fine printed material has been readily produced. However, it is impossible with such techniques to provide the three-dimensional effects possible with embroidery.

U.S. Pat. No. 6,189,989 B1 discloses a printing device aiming to mitigate at least some of the above mentioned problems by an ink jet printing apparatus having a station for dyeing a thread for embroidering by discharging ink onto the thread from an ink jet head. According to one aspect, a printing controller controls the amount of ink discharged per unit time onto the thread according to the speed of the relative movement of the thread and the ink jet head. However, the device is complex and the ink jet head provides unsatisfactory ink coverage of the thread. It is desirable to obtain as small droplets as possible, to obtain an optimized result. Therefore, an ink jet head ink nozzle needs to be sufficiently small. Furthermore, a small nozzle is needed to maintain ink inside ink jet head when no ink discharge is wanted. Further, the larger the nozzle diameter, the larger the discharged droplets become, which eventually lead to leakage of ink. A small ink jet nozzle is typically also accompanied by technical problems, such as increased risk of clogging, leading to the risk of uneven ink distribution, and short life span and/or costly. All in all, this jeopardizes the precision of the ink distribution, which is vital for a thread coloring thread consuming machine, since failure in this respect leads to wrong color appearing on the wrong position.

Hence, an improved coating device and thread consuming system solving the above described deficiencies would be beneficial.

SUMMARY

An object of the present invention is to provide a novel device for applying liquid, such as ink, to a single thread as said thread moves relative to the device along a path of movement, which device is improved over prior-art devices of the type discussed above.

A particular object of the present invention is to provide a novel coating device for dynamically applying liquid, such as ink, to a single thread for a thread consuming device as said thread moves relative to the coating device along a path of movement, which coating device is improved over prior-art devices of the type discussed above.

A particular object of the present invention is to provide a novel coating device for dynamically applying ink to a single thread for an embroidery machine as said thread moves relative to the coating device along a path of movement, which coating device is improved over prior-art coating devices of the type discussed above.

A particular object of the invention is to provide such an improved coating device, providing a better ink coverage of the thread.

Another object is to provide a less complex coating device.

Another object is to provide a coating device allowing for decreased risk of clogging and improved exactness of ink distribution.

Another object is to provide a coating device with increased life span.

These and other objects, which will appear from the following description, have now been achieved by a device, a system and an embroidering method according to the appended independent claims. Advantageous embodiments are set forth in the dependent claims.

A coating device according to the invention handles application of ink to a thread and is typically fitted into a thread-consuming device comprising other machine elements, such as means for feeding the thread and means for embroidering using the thread.

A coating device according to a first aspect of the invention is suitable for dynamically applying ink to a single thread for embroidery as said thread moves relative to the coating device along a path of movement. The coating device is configured to apply ink to said thread by means of an electro spraying unit comprising at least one emitter, thread guiding means, ink supply means, voltage supplying means, counter electrode means and an ink flow controller. The voltage supplying means is arranged to supply a variable voltage or a modulated voltage, such as an alternating voltage. Each respective emitter is suitable for discharging ink from a respective discharge edge, such as a discharge tip or a discharge orifice, towards the thread in a discharge direction, such that a respective discharge zone is formed. Further, the thread guiding means is configured to guide the thread through each respective discharge zone. The ink supply means is suitable for supplying ink to said at least one emitter, and the voltage supplying means is configured to provide an electric potential between the at least one emitter and the counter electrode means. Also, said emitter and said at least one counter electrode means are configured such that an electric field is created between each respective emitter and the counter electrode means to obtain the discharge zone of each respective emitter. Further, the ink flow controller is configured to control the ink supply means and the voltage supplying means in response to a control signal for controlling ink output.

Such a coating device provides improved ink coverage on said thread.

According to an embodiment of the invention, the coating device comprises a diversion electrode means configured to affect the path of movement of emitted ink by means of at least one electric field. The diversion electrode may accomplish by-passing of undesired drops of liquid from the flow path towards the thread. For example, the first set of droplets from the emitter may be of unknown or unwanted size or potentially contaminated, and thus being undesired to hit the thread. The diversion electrode may also be used to direct droplets towards the thread, by alternating its potential in comparison with its setting during by-passing mode. In this way mechanical alignment may be avoided. It is also possible to let the diversion electrode alternate in potential or being applied with a potential sequentially to by-pass droplets passed the thread or to allow droplets to reach the thread. The diversion electrode may also be positioned such that it may trap “escaping” droplets.

Such a coating device makes it possible to dynamically adjust the direction of discharge of ink and/or the shape of the discharge zone. This in turn leads to lower requirements on mechanical tolerances of the guiding means and thus provides for a less expensive and less complicated coating device.

According to a further embodiment, said coating device comprises a plurality of emitters arranged in a monolithic block. This provides for improved precision of ink application to the thread.

According to another embodiment, a plurality of emitters is arranged in series along the path of movement of the thread. This makes it possible to use multiple emitters, thereby providing improved ink coverage. Also, it provides a simple and inexpensive arrangement that makes it possible to hit the thread with ink from all around the thread in the case of threads that are twisting/rotating along their respective longitudinal direction.

According to an embodiment, the one or more emitters are arranged perpendicularly relative the path of movement of the thread. This brings the advantage that the degree of coverage is increased, since the ink typically hits the thread more symmetrically.

According to a further embodiment, shielding means are provided between the emitters. The shielding means are configured to electrostatically shield the discharge zones from each other. This promotes independent operation of adjacent emitters, since charged droplets from one emitter, or the emitters respective electrical field, will not affect the performance of other emitters.

According to yet an embodiment, the shielding means is configured to be connected to electric ground. This arrangement makes is possible to continuously remove excess charges from ink droplets hitting the shielding means.

According to another embodiment, each respective emitter is coated with a hydrophobic material. The hydrophobic coating prevents ink from wetting over outer surfaces of the emitter, which in turn is advantageous since fluid on the outer surface affects the droplet size and frequency of emission of droplets, and also the direction and stability of droplets thereby making it difficult to control ink discharge.

According to an embodiment, the at least one emitter comprises a capillary tube with a central passage defining the discharge edge, which in this embodiment comprises a tip with an orifice. The capillary tube is commonly available as such, and used in a coating device according to the invention it makes it possible to lower production costs while maintaining high precision. Further, the capillary tube consumes very little space and therefore provides for a compact design of said coating device. Still further, the capillary tube allows for a capillary nozzle having low risk of clogging, due to its relatively large diameter, thus improving life span and exactness of ink distribution.

According to a further embodiment, the at least one emitter comprises a plate with a thorough hole defining the discharge orifice. The plate is easy to manufacture with high precision at low cost. Further, the plate makes it easy to connect the emitter to the voltage supplying means. Also, several emitters may be integrated into a monolithic construction in an inexpensive manner by simply making the plate slightly bigger and providing further holes.

According to yet an embodiment, each emitter is coupled to an individual ink supply means comprised in said ink supply means. This brings the advantage that the ink flow to each respective emitter can be individually controlled, thus allowing for a more complex control algorithm to be used, which in turn makes it possible to simultaneously control the supply of a plurality of colors to the emitters of the electro-spray unit and thereby provide a wide range of colors on the thread by appropriately dispensing various amounts of said plurality of colors.

According to an embodiment, an extractor electrode is provided adjacent each respective discharge orifice. The extractor electrode promotes discharge of ink from each respective emitter. Also, the voltage supplying means is configured to provide a potential between each respective emitter and the extractor electrode. A device according to this embodiment brings an advantage in that lower voltages may be utilized for promoting discharge of ink, since the distance between the extractor plate and the emitter is typically much smaller than the distance between the emitter and the counter electrode means. Also, alignment between the nozzle and the thread is simplified by means of the E-field that the extractor electrode creates.

According to a further embodiment, the extractor electrode is plate-shaped and has a central through hole aligned with the discharge orifice. This brings an advantage in that the plate is easy to manufacture with high precision at low cost. Further, the plate makes it easy to connect the extractor electrode to the voltage supplying means. Also, several extractor electrodes may be integrated into a monolithic construction in an inexpensive manner by simply making the plate slightly bigger and providing further holes.

According to yet an embodiment, the plate-shaped extractor electrode is arranged substantially perpendicular to the discharge direction. This brings an advantage in that that it promotes a symmetric discharge pattern, which in turn increases the degree of coverage and provides for a more even ink covering of the thread.

According to yet another embodiment the plate-shaped extractor electrode comprises a multitude of layers, such as two or three layers, said layers being arranged transversally to the through hole. The different layers may have different polarity, such that the polarity of the layer comprising the side facing the substrate, i.e. the thread, for example may be of a positive potential while the layer comprising the side facing the emitter is of a negative potential, when the emitter is positively charged. In this embodiment the liquid being discharged from the emitter, and thus having the same potential as the emitter, may be kept from being attracted to the extractor electrode, and will continue towards the substrate, i.e. the thread.

According to an embodiment, the electrospraying unit is provided with a thread contacting means configured to provide electrical contact between the voltage supplying means and the thread. The voltage supplying means is also configured to provide a potential between each respective emitter and the thread. This brings an advantage in that it is possible to adjust the potential between the emitter and the thread. This in turn makes it possible to remove electrical charges that ink droplets bring to the thread. Further it makes it possible to at least partly use the thread as an electrode of the counter electrode means. Also, it makes it possible to better attract satellite ink droplets to the thread, thus reducing ink consumption, increasing ink coverage on the thread and reducing contamination of surrounding machine elements.

According to another embodiment, the counter electrode is the thread. This brings a further advantage in that no other electrode is needed for the counter electrode means.

According to yet an embodiment, the thread contacting means is configured to contact the thread at a position in which the thread has already passed a discharge zone. This brings an advantage in that electrical charges brought by droplets of ink in the discharge zone will be removed before they distract the droplets from other nozzles along the path of movement of the thread.

According to an embodiment, the thread contacting means is configured to contact the thread before it passes the first discharge zone along the path of movement. This brings an advantage in that any electrical charges present on the thread will be removed before it reaches the first discharge zone along its path of movement. This in turn provides for better control of the threads ability to receive ink droplets.

According to a further embodiment, the coating device is provided with a wetting means configured to make the thread more electrically conductive by application of a wetting agent, such as an electrically conductive liquid. This brings an advantage in that a wider selection of materials can be used for said thread despite any need of having a conductive thread. Further it typically makes the thread more prone to absorbing ink droplets applied thereto. The wetting of the thread may also improve color mixing and soaking of the thread. When the wetting of the thread is performed to improve color mixing and soaking of the thread, the wetting agent is selected such that its characteristics are similar to the liquid characteristics of the liquid, such as an ink, intended to coat the thread. If the liquid, such as an ink, is a water-based ink, a polar wetting agent, such as a protic or aprotic polar wetting agent, may be selected, such as water; ethanol; methanol; acetic acid; propanol; butanol; formic acid; ethyl acetate; acetone; acetonitrile; etc., and if the liquid, such as an ink, is non polar, such as oil based, a non-polar wetting agent may be selected, such as alkanes, in form of pentane, cyclopentane, hexane, etc.; benzene; toluene; chloroform; diethyl ether; etc. Of course, combinations of these specific wetting agents are also within the ambit of the invention, as long as the wetting agent aims at having the same characteristics as the liquid intended to coat and/or soak the thread.

According to yet an embodiment, the ink-flow controller is configured to operate in a micro dripping mode. By operating the ink-flow controller in the micro dripping mode, a flow of ink dispersed in droplets may be achieved, which in turn provides for a good ink coverage on the thread.

According to a further embodiment of the invention, the coating device further comprises a fixation device for fixing non-fixated ink to the thread. Thereby, contamination of the system by non-fixated ink is prevented. Also, smearing of non-fixated ink along the thread is prevented.

According to an embodiment, the fixation device is configured to fix the ink to the thread before non-fixated ink reaches the guiding means after the discharge zone. Thereby, non-fixated ink is prevented from being scraped off the thread when the thread passes a thread guiding means.

According to yet an embodiment, the coating device further comprises at least one treatment device for treatment of the thread before coloring, after coloring, after fixating, or a combination thereof. Thereby, sewability of the thread may be improved before the thread reaches the thread consuming device. The treatment device may be used singly, separately, or in combination with a coating device and/or thread consuming device, such as a coating device and/or thread consuming device, wherein the thread is coated by means of electro spaying, ink jet, or similar coloring techniques.

According to an embodiment, the treatment device is configured to receive the thread after the fixating device. Thereby, the fixating device is prevented from negatively affecting sewability of the thread after the thread has passed the treatment device.

According to an embodiment, the treatment device is configured to receive the thread before the electrospraying unit. Thereby, the thread may be pretreated to enhance coloring ability, enhancing sewability, etc., before the thread enters the electrospraying unit.

According to a further embodiment, the treatment device is configured to wash the thread. Washing of the thread effectively improves sewability of the thread and removes any dust or other unwanted substances present on the thread. Washing may be performed before and/or after the fixating unit, and after coloring.

According to yet an embodiment, the treatment device is configured to lubricate the thread. Thereby, lubricity of the thread is increased, wherein sewability is typically also improved. Lubricating may be performed before and/or after the fixating unit, and after coloring.

According to another aspect of the invention an embroidery system is provided. The system comprises a coating device according to an embodiment of the invention. Further, the system comprises thread feeding means, embroidery means and a pattern controller. The thread feeding means is configured to feed the thread through the guiding means of the coating device. The embroidery means is suitable for embroidering a pattern on an object using the thread based on pattern information. Also, the pattern controller provides control signals to said ink flow controller in response to at least the pattern information. Such a system brings an advantage in that embroidery may be performed with improved ink coverage and a higher degree of ink coverage of the thread embroidered.

According to yet an aspect of the invention a method of applying ink to an embroidery thread by means of a coating device according to an embodiment of the invention is provided. The method comprises a step of feeding the thread through the coating device while discharging ink onto said thread using said electrospraying unit. This method brings an advantage in that it provides improved ink coverage and a higher degree of ink coverage of the thread embroidered.

According to another embodiment of the invention, the method further comprises a step of wetting the thread before feeding said portion through a discharge zone. Wetting the thread makes it more electrically conductive and typically also improves its ability to quickly absorb ink droplets. Wetting also improves color mixing.

The method may further comprise controlling the wetting with regards to the amount of the wetting agent used in relation to the thread consumption to achieve a certain color quality (uniformity), better fixation and/or better sewability.

The method may also comprise controlling the lubrication with regards to the amount of the lubricant used in relation to the thread consumption to achieve a certain color quality (uniformity), better fixation and/or better sewability.

BRIEF DESCRIPTION OF THE DRAWINGS

Each one figure of FIGS. 1-6 shows a schematic view of a coating device according a respective embodiment of the invention.

FIG. 7 shows a schematic view of an embroidery system according to an embodiment of the invention.

DETAILED DESCRIPTION

As previously mentioned, an aspect of the invention relates to a device for dynamically applying liquid, such as ink, to a single thread as said thread moves relative to the device along a path of movement. In this way, a thread may be coated or soaked with a liquid, such as an ink. The device is configured to apply liquid to the thread by means of an electrospraying unit. More specifically, the device is a thread consuming device, such as an embroidery machine, for applying ink to a single thread, such that the thread may be coated with said liquid, such as ink. When the device is a thread consuming device, such as an embroidery machine, for applying ink to a single thread, the device may be said to be a coating device. A thread may be glass fiber thread; a thread of wool; a thread of cotton; a synthetic thread; a metallic thread; a thread being a mixture of wool, cotton, polymer, or metal; a yarn; filament; or any elongated substrate that is intended and/or being suitable for being applied with liquid, such as ink.

A coating device 100 according to a first embodiment of the invention will now be described with reference to FIG. 1. The coating device 100 comprises an electrospraying unit comprising an emitter 101. The coating device 100 also comprises a thread guiding means 102, ink supply means 103, voltage supply means 104, counter electrode means 105 and an ink flow controller 106. The emitter 101 is suitable for discharging ink through the use of a discharge unit, such as an emitter edge 107, such as an emitter tip or orifice, towards the thread T in a discharge direction such that a respective discharge zone 108 is formed. By applying an electrical field over a surface comprising one or more edges, on which ink is applied, an electrical field which is stronger at the edge(s) is generated which causes the ink (being a liquid) to disperse. In one embodiment the emitter edge is a tip arranged with an orifice through which ink can be supplied to the emitter tip.

In one embodiment the emitter 101 is arranged for discharging ink through an orifice in the emitter tip 107 towards the thread T in the discharge direction to form the discharge zone 108.

Further, the thread guiding means 102 is configured to guide the thread T through the discharge zone 108. The ink supply means 103 is suitable for supplying ink to the emitter 101, and the voltage supplying means 104 is configured to provide an electric potential between the emitter 101 and the counter electrode means 105. Also, said emitter 101 and said counter electrode means 105 are configured such that an electric field created between the emitter 101 and the counter electrode means 105 spans through the discharge zone 108. Further, the ink-flow controller 106 is configured to control the ink supply means 103 and the voltage supply means 104 in response to a control signal. The ink-flow controller 106 is preferably controlled such that a stable frequency of droplet discharge is achieved from the emitter 101, by appropriately adjusting the voltage controlling the potential between the emitter 101 and the counter electrode means 105, while at the same time appropriately controlling ink flow from the ink supply means 103 to the emitter 101 in relation to the desired color and relative speed of the thread. The droplet discharge may also be pulsed. This kind of adjustment related to electrospraying is known in the art and various known types of spray characters, or ‘spraying modes’, may be achieved, such as ‘dripping’, ‘micro dripping’, ‘spindle’, ‘multispindle’, ‘ramified-meniscus’, ‘oscillating-jet’, ‘precision’, ‘cone-jet’, ‘multijet’, and ‘ramified-jet’. In a preferred embodiment of the invention, the ink-flow controller 106 is configured to operate in the ‘micro dripping’ spray mode, since that promotes intended ink coverage on the thread T. By operating the ink-flow controller 106 in the micro dripping mode, a flow of ink dispersed in very small droplets may be achieved. The small size droplets are advantageous, especially for low flows, and promote said intended ink coverage on the thread.

In the first embodiment, the counter electrode means 105 comprises a single electrode. In another embodiment it could however comprise several electrodes.

Also, in the first embodiment the emitter 101 is a capillary pipe. In another embodiment it could however take other forms, such as a plate with a thorough hole defining the capillary. In a further embodiment, the hole is surrounded by a ridge extending from the plate in the axial direction of the hole. The ridge prevents ink from spreading on the plate surface around the capillary.

Further, in the first embodiment the ink supply means 103 comprises a single ink supply means connected to the emitter. In another embodiment, the ink supply means 103 may however comprise a separate ink supply means for each emitter or at least a separate ink supply means for a group of emitters to be fed with same color ink.

In an embodiment (not shown), the guiding means 102 is configured to twist or rotate the thread along its length.

The guiding means 102 may be used singly, separately, or in combination with a coating device and/or thread consuming device, such as a coating device and/or thread consuming device, wherein the thread is coated by means of electrospaying, ink jet, or similar coloring techniques. Thus, it is not necessarily so that only threads for dying with electrospraying may benefit from the guiding means 102, but also other coating devices using thread may benefit from it. As such, the guiding means 102 may solve problems independent of type of coating devices 100 with electrospraying units.

A coating device 200 according to a second embodiment will now be described with reference to FIG. 2. This coating device 200 is basically identical to the one of the first embodiment except for some minor changes. For example, it additionally comprises an extractor electrode 109 in the form of an extractor plate. The extractor electrode 109 comprises a through hole. The extractor electrode 109 is provided adjacent the discharge orifice 107, such that discharge of ink from the emitter may pass through the through hole, for promoting discharge of ink at a lower voltage. For this to work, the voltage supply means 104 is modified such that it now also provides a potential between the emitter 101 and the extractor electrode 109. If the voltage supply means also is connected to the counter electrode means 105, said counter electrode means 105 will further act as an ink collector, for minimizing ink contamination of the rest of the equipment.

In one embodiment the extractor electrode 109 may comprise a multitude of layers, such as two or three layers, said layers being arranged transversally to the extension of the through hole. Two layers of electrically conductive material may then be provided with different polarity, such that the polarity of the layer comprising the side facing the substrate, i.e. the thread, for example may be of a positive potential while the layer comprising the side facing the emitter is of a negative potential, when the emitter is positively charged. In this way, the liquid being discharged from the emitter, and thus having the same potential as the emitter, may be kept from being attracted to the extractor electrode, and will continue towards the substrate, i.e. the thread. Between the two layers of conductive material comprising the sides facing the emitter and the thread, respectively, a layer of an insulating material may be provided, to prevent short-circuiting. It is also possible to have an air gap between the two layers.

A coating device 300 according to a third embodiment will now be described with reference to FIG. 3. This coating device 300 is basically identical to the one of the first embodiment 100 but additionally comprises a thread contacting means 110. The thread contacting means 110 is configured to provide electrical contact between the voltage supply means 104 and the thread T. For this to work, the voltage supply means 104 is configured to provide a potential between the emitter 101 and the thread T, i.e. by means of an extra cable and an extra voltage regulator. Thus, a first potential is setup between the emitter 101 and the extractor plate 109, while a second potential is setup between the emitter 101 and the thread T. This brings an advantage in that it is possible to adjust the potential between the emitter 101 and the thread T. This in turn makes it possible to remove electrical charges that ink droplets bring to the thread T, which would otherwise risk misleading the ink droplets. Further it makes it possible to at least partly use the thread T as an electrode of the counter electrode means 105. Also, it makes it possible to better attract satellite ink droplets to the thread T, thus reducing ink consumption, reducing contamination of the device and increasing the dying quality.

A coating device 400 according to a fourth embodiment will now be described with reference to FIG. 4. The coating device 400 is basically identical to the coating device 300 of the third embodiment, except for that it does not have a counter electrode 105 or an extractor electrode 109. Further, the thread T is used as a counter electrode and no other counter electrode exists. In order to achieve this, the thread contacting means 110 is still used according to the same principle as in the third embodiment, for providing an electric potential between the emitter 101 and the thread T. In order for the thread T to function as an electrode, at least a portion of the thread T has to be, or be made, electrically conductive such that electric connection exist between the thread contacting means 110 and a portion of the thread present in the discharge zone 108. For example, the thread T may be continuously wet before being fed into the electrospraying unit.

The pretreatment of the thread as disclosed above, may also be achieved by heating, ionizing, corona or plasma treating the thread in order to improve the colored thread's resulting characteristics as regards coloring, structure, texture, sewabaility and friction to name a few characteristics.

The thread contacting means 110 may also be used to charge the thread T even if the thread is not electrically conductive. The charges of the thread then attract ink droplets as the charges pass the discharge zone.

A coating device 500 according to a fifth embodiment will now be described with reference to FIG. 5. Here, the coating device 500 is basically identical to the coating device 300 of the third embodiment, except for that the thread T is used as a counter electrode and no other counter electrode exists. In order to achieve this, the thread contacting means 110 is still used according to the same principle as in the third embodiment, for providing a potential between the emitter 101 and the thread T. As described above, with reference to the fourth embodiment, the thread T has to be made electrically conductive.

Furthermore, a coating device 600 according a sixth embodiment will now be described with reference to FIG. 6. Here, the coating device 600 is similar to the coating device of the second, third and fifth embodiment, except for that it does not have any counter electrode means 105 and also no thread contacting means 110. Thus, the only electric potential used to discharge ink from the emitter 101 is provided by means of an extractor electrode 109, for example any one of the previously described extractor electrodes.

In other embodiments, a plurality of emitters 101 could be provided in the electrospraying unit. The emitters could either be used to dispense different colors or to dispense the same color more than once.

According to further aspect of the invention an embroidery system 700 is provided. Such a system will now be described with reference to FIG. 7. The system 700 according to this embodiment comprises a coating device 100 according to the first embodiment of the invention, but could however comprise a coating device according to any other embodiment of the invention. In addition to the coating device, the system 700 comprises thread feeding means 111, embroidery means 112 and a pattern controller (not shown). The thread feeding means 111 is configured to feed the thread T through the guiding means 102 of the coating device 100. The embroidery means 112 is suitable for embroidering a pattern on a substrate S using the thread T based on pattern information. Also, the pattern controller provides control signals to said ink flow controller 106 in response to at least the pattern information, but possibly also other information, such as thread speed, ink type, thread type, temperature and humidity level in surrounding air. The pattern information describes the pattern, i.e. what color is supposed to go where on the thread. The pattern information may also comprise information regarding the stitches and the path of the needle over the substrate S.

At one side of the coating device there is provided a thread supplier 113, such as a thread bobbin or reel of thread, holding the thread T to be fed into the coating device 100. Similar bobbins are known in the art.

After leaving the thread supplier 113 the thread T passes a thread tensioning device 114 configured to keep the thread T appropriately tensioned during operation of the system 700. Similar thread tensioning devices are known in the art.

After the coating device 100, the thread T passes an ink fixation device 116, a buffer device 117 and a thread feeding means 111 configured to feed or pull the thread T through said coating device 100 via said guiding means 102. The feeding means 111 is driven by a suitable electric motor 115 preferably controlled by the thread consumption of the thread consuming device. The buffer device 117 compensates for the intermittent thread speed of the embroidery means 112 and such buffer devices 117 are known in the art. The ink fixation device 116 is configured to fixate the ink to the thread T before non-fixated ink reaches the guiding means 102 after the discharge zone. Thereby, contamination of the system 700 by non-fixated ink is prevented. Also, smearing of non-fixated ink along the thread T is prevented. In one embodiment the ink fixation device 116 is a combined ink fixation and drying device 116 for both drying the thread (T) and for fixating the ink on the thread (T), for further prevention of contaminating the system 700.

Optionally, a thread treatment device 118 may be provided after the fixating device 116 treatment of the thread T in order to make the thread suitable for further handling of the thread consuming device (the embroidery means 112). The thread treatment device 118 is configured to receive the thread T after the fixating device 116. Thread treatment post application of ink may for example comprise washing of the thread T and/or lubrication of the thread T. The treatment device 118 may be used singly, separately, or in combination with a coating device and/or thread consuming device, such as a coating device and/or thread consuming device, wherein the thread is coated by means of electrospaying, ink jet, or similar coloring techniques. Thus, it is not necessarily so that only threads for dying with electrospraying may benefit from the treatment device 118, but also other coating devices using thread may benefit from it. As such, the treatment device may solve problems independent of coating devices 100 with electrospraying units.

When the thread T is colored by the coating device, the thread T may become stiffer and somewhat rougher. In order for the thread to be suitable for e.g. a thread consuming device performing sewing or embroidering, its ‘sewability’ should be good. Sewability is typically improved by treatment with the thread treatment device. Typically, sewability is improved by improving the lubricity of the thread T, which in turn is achieved by lubrication. The lubrication may be obtained by means of a wax- or silicone based lubricant.

Such a system 700 brings an advantage in that embroidery may be performed with more even ink coverage and a higher degree of ink coverage of the thread used for embroidering.

In one embodiment of the systems described above a maintenance unit (not shown) is arranged to clean and maintain the emitters, the wetting unit, the lubrication unit, thread treating unit, and/or washing unit. The maintenance unit may comprise a cleaning means, such as a scraper, a brush, a pneumatic unit, and/or a hydrodynamic unit, for cleaning the emitter, the wetting unit, the lubrication unit, thread treating unit, and/or washing unit, through blowing or suction, or a flushing unit for flushing the emitter, the wetting unit, the lubrication unit, the thread treating unit, and/or the washing unit.

The maintenance unit may further comprise an ink collector means for collecting ink. The ink collector means may comprise a funnel, a sponge, a filter or a fan to name a few.

The maintenance unit may further comprise a fume directing means for directing ink fumes. The collector means may comprise or work according to a filter, a fan, a chimney effect possibly caused by the heat generated by the fixation device. The collector means may also be arranged to be controlled with electrical fields for capturing or collecting fumes and other residue in specially adapted collector vessels or filters.

The maintenance unit may further comprise a collector means for collecting surplus lubrication, surplus washing solutions from the thread treating unit.

In one embodiment of the systems disclosed above the system may comprise means for controlling the wetting with regards to the amount of the wetting agent used in relation to unit of length of the thread to achieve a certain color quality (uniformity), better fixation and/or better sewability.

In one embodiment of the systems disclosed above the system may comprise means controlling the lubrication with regards to the amount of the lubricant used in relation to the thread consumption to achieve a certain color quality (uniformity), better fixation and/or better sewability.

The systems above may be provided with a drop diversion unit, such as a diversion electrode (not shown). The diversion electrode may be provided with the opposite potential of the emitter (and thus the liquid). The diversion electrode may be positioned beneath the thread, i.e. on the opposite side of the thread in comparison with the emitter. When a diversion electrode is positioned on the opposite side of the thread in comparison with the emitter, the diversion electrode and/or the emitter may also be positioned laterally of the thread, such that the thread not is positioned in the direction of the emitter. In this way, the diversion electrode may direct the droplets towards the thread when the diversion electrode is provided with a different/opposite potential than the emitter, while droplets will miss the thread when no potential is applied on the diversion electrode.

The diversion electrode may also be a separate diversion electrode unit, comprising a potential plate on each side of the droplet patch towards the thread. By applying a potential between the two plates the droplet may be guided by the electrical field between the potential plates of the diversion electrode, towards or away from the thread. If the emitter is positioned laterally of the thread, the electrical field between the potential plates of the diversion electrode may guide the droplets towards the thread, and when the thread is positioned in the direction of the emitter, the electrical field between the potential plates of the diversion electrode may guide the droplets away from the thread.

As used herein, “embroidery” refers to forming patterns by stitching on a suitable base material or substrate.

Typically, each respective emitter is configured to discharge either cyan, magenta, yellow or black ink, respectively, although other colors and types of ink or liquids may be used, if desired. For example, instead of discharging colored ink, liquids for achieving special effects may be used, such as metallic-, neon- and/or special coating for smart textiles, etc. Ink is discharged from the emitters in accordance with the wanted color and at least the speed of the thread. That is, when the speed of the thread is low, ink is discharged at a low flow rate, and when the speed of the thread is high, ink is discharged at a high flow rate, whereby a thread dyeing operation can be performed in full cooperation with the embroidery apparatus.

In addition, plural inks of different colors can be mixed on a thread in accordance with the pattern information so that the thread can be coated in a substantially unlimited number of colors.

The invention also relates to methods of operating the coating devices and systems according to the various embodiments described above.

The invention can be implemented in any suitable form including hardware, software, firmware or any combination of these. The elements and components of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the invention may be implemented in a single unit, or may be physically and functionally distributed between different units and processors.

Although the present invention has been described above with reference to specific embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the invention is limited only by the accompanying claims.

In the claims, the term “comprises/comprising” does not exclude the presence of other elements or steps. Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly advantageously be combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality. The terms “a”, “an”, “first”, “second” etc. do not preclude a plurality. Reference signs in the claims are provided merely as a clarifying example and shall not be construed as limiting the scope of the claims in any way.

Claims

1.-42. (canceled)

43. A device for applying liquid to a single thread as said thread moves relative to the device along a path of movement, wherein said device is configured to apply liquid to said thread by means of an electrospraying unit comprising:

at least one emitter for discharging liquid through a respective discharge nozzle towards the thread in a discharge direction, such that a respective discharge zone is formed,

thread guiding means configured to guide the thread through each respective discharge zone,

liquid supplier for supplying liquid to said at least one emitter, and voltage supply means, configured to provide an electric potential between the at least one emitter and a counter electrode means, said emitter and said counter electrode means being configured, such that an electric field created between each respective emitter and the counter electrode means discharges liquid into said discharge zone.

44. The device according to claim 43, wherein said electrospraying unit further comprises a liquid flow controller configured to control the liquid supply means and the voltage supplying means in response to a control signal.

45. The device according to claim 43, wherein said device comprises a plurality of said emitters.

46. The device according to claim 45, wherein the emitters are arranged in series along said path of movement.

47. The device according to claim 43, wherein each respective emitter is coated with a hydrophobic material.

48. The device according to claim 43, wherein the at least one emitter comprises a capillary tube with a central passage defining the discharge orifice.

49. The device according to claim 43, wherein each emitter is coupled to an individual liquid supply means comprised in said liquid supply means.

50. The device according to claim 43, wherein said electrospraying unit is further provided with a thread contacting means configured to provide electrical contact between the voltage supplying means and the thread, wherein the voltage supplying means is also configured to provide a potential between each respective emitter and the thread.

51. The device according to claim 43, further comprising a treatment device in form of a wetting means, configured to make at least a portion of the thread electrically conductive by application of electrically conductive liquid.

52. The device according to claim 43, wherein the liquid-flow controller is configured to operate in a micro dripping mode.

53. The device according to claim 43, further comprising a fixation device for fixing non-fixated liquid to the thread.

54. The device according to claim 43, further comprising a thread treatment device for treatment of the thread.

55. The device according to claim 54, wherein the thread treatment device is configured to wash the thread.

56. The device according to claim 54, wherein the thread treatment device is configured to lubricate the thread.

57. The device according to claim 43, wherein said device is a coating device for applying ink on a single thread.

58. The device according to claim 43, wherein the device is or is a part of a thread consuming device, for dynamically applying liquid, such as ink, to a single thread.

59. The device according to claim 58, wherein the thread consuming device is a sewing machine or an embroidery machine, for dynamically applying liquid, such as ink, to a single thread.

60. A system for applying liquid, such as ink, to a single thread, said system comprising:

a device according to claim 43; and

thread feeding means configured to feed the thread through said thread guiding means.

61. The system according to claim 60, wherein said system is an embroidery system further comprising:

embroidery means, for embroidering a pattern on a substrate using the thread, based on pattern information, and

a pattern controller providing control signals to a liquid flow controller in response to at least the pattern information.

62. A method of applying liquid, such as ink, to a thread, comprising the steps:

feeding a thread through a discharge zone;

applying a voltage between at least one emitter and a counter electrode means, and electrospraying liquid at said thread as a result of said voltage.

63. The method according to claim 62, further comprising applying liquid, such as ink, to the thread by means of a device according to claim 43, and feeding a thread through the device according to claim 43 while discharging liquid onto said thread using said electrospraying unit.

64. The method according to claim 62, comprising a further step of wetting at least a portion of the thread with a wetting agent before feeding said portion through a discharge zone.

65. The method according to claim 64, wherein the wetting agent is a polar wetting agent when the liquid is a polar liquid, and wherein the wetting agent is a non-polar wetting agent when the liquid is non-polar.

66. The method according to claim 62, comprising a further step of lubricating at least a portion of the thread before or after feeding said portion through a discharge zone.

67. A device for applying liquid to a single thread as said thread moves relative to the device along a path of movement, wherein said device is configured to apply liquid to said thread by means of at least one emitter for discharging liquid through a respective discharge nozzle towards the thread in a discharge direction,

liquid supplier for supplying liquid to said at least one emitter, and

a thread treatment device for treatment of the thread, wherein the thread treatment device is configured to wash the thread, lubricate the thread, or wet the thread.