1. Field of the Invention
This invention relates to curing assemblies and, in particular, this invention relates to assemblies curing UV-curable ink or coating on a substrate.
2. Background
High intensity LED devices present great challenges in designing thermal and optical energy and optical energy management. One particular problem when designing LED light-emitting systems is that one must focus high levels of narrow or spot-focused energy in limited or small spaces, at heat-sensitive locations, or in otherwise hazardous locations. These applications may require a physically compact, low heat-emitting, focused (non-scattered) and electrically or intrinsically safe light source device at the working location. One typical application where these problems exist is, but is not limited to, curing UV (Ultraviolet) curing ink in an ink jet printing device, more specifically, the “pinning” or pre-curing (gelling) of dispensed UV ink jet printing ink. Following the dispensing of ink jet ink onto a substrate a “pinning” function is often employed. Ink jet heads must be grouped closely together when multiple colors are used to produce sharp clear images, whereas if not, the ink has a tendency to “sag” or blend together, thereby obscuring the crispness or sharpness of the image being printed. Because ink jet printing “heads” or nozzles must be grouped tightly together when multiple ink colors are dispensed, this gives rise to the need to employ the device disclosed herein. Further, the non-focused or randomly scattered light energy typically present in UV LED devices utilized for this purpose causes the UV ink to cure or gel on the heads or nozzles, thus impairing function, the impaired function resulting in reduced quality of printed media and an increase in maintenance time to clean the heads.
Additionally when pinning ink printed on substrates, the present known curing devices require the ink jets to be separated so as to allow these curing devices to deliver sufficient radiation to the ink on the printed substrate. This separation often results in a printed substrate having less than optimal clarity.
There is then a need for a curing device which cures ink with a radiation pattern which is flexible in shape and intensity, but which transmits little or no heat to the substrate being radiated and which minimizes the distance between ink jets.
This invention substantially meets the aforementioned needs of the industry by providing:
A device that utilizes, but is not limited to utilizing individually or in combination, fiber optic transmission bundles of glass or polymer, optical lenses or lens assemblies of glass or polymer, solid fiber (large scale) or similar light transmission methods.
A device, in one embodiment, that transmits the light from a square or rectangular LED light source to a narrow and compact emitting head or lamp.
A device that requires no cooling of thermal energy at the emitting head or lamp unit.
A device that can be fabricated in many shapes allowing it to be positioned between the ink jet print heads in a typical multi-color ink jet printing system.
A device that be rendered intrinsically safe, thus allowing it to operate in hazardous locations.
A device that can be custom tailored physically to integrate in, but not be limited to, many commercially produced printing, coating, dispensing and dosing machines.
A device that can be fabricated to operate in many optical energy emitting configurations.
A device that can be positioned within, but not be limited to a distance of 10 mm or less from the media or curing surface.
A device that emits zero or near zero excess thermal energy at the emitter or lamp unit.
Accordingly, there is provided a curing assembly having a singular lens or a plurality of lenses (optionally including a lens assembly), a fiber optic cable and a pinning head. The fiber optic cable has a plurality of optic fibers receiving light which has passed through the lens. The head positions the optic fibers so that light emitted from the optic fibers impinges a substrate in a geometric pattern. The geometric pattern may be remote from any light generator, which may also generate heat. The head may be fixed in a position relative to the substrate. The optic fibers may be fixed within the head as the head is manufactured. In some embodiments, a plurality of either or both of light generators or pinning heads (for example, bifurcated or trifurcated) will be present, in which case differing wave spectra with differing peak wave lengths can be generated and blended.
In some embodiments, light leaves a light source, passes through a lens or lens assembly for collimation, passes through another lens or lens assembly for focusing on the fiber bundle cable, which then transmits the light to the substrate. While light emitted directly from optic fiber ends may directly impinge the substrate, light emitted from optic fiber ends may pass through an optic, such as a rod optic or another optic with a hemispherical or aspherical profile to further focus the light before the light impinges the substrate.
These and other objects, features, and advantages of this invention will become apparent from the description which follows, when considered in view of the accompanying drawings.
a is a top view of one embodiment of a pinning head of this invention for transmitting radiation to a substrate.
b is a side view of the pinning head of
c is a bottom view of the pinning head of
d is an end view of the pinning head of
e is a perspective view of the pinning head of
f is another perspective view of the pinning head of
a is a top view of the pinning head of
b is a side view of the pinning head of
c is a bottom view of the pinning head of
d is an end view of the pinning head of
e is a perspective view of the pinning head of
a is a side view of one embodiment of a fiber optic-transmitted curing apparatus of this invention.
b is a bottom view of the curing apparatus of
c is an end view of the curing apparatus of
d is a perspective view of the curing apparatus of
a is a frontal view of another embodiment of the curing apparatus of this invention.
b is a perspective view of the curing apparatus of
a is a bottom view of another embodiment of a fiber optic-transmitted curing apparatus of this invention.
b is a front view of the curing apparatus of
c is a perspective view of the curing apparatus of
d is a side view of the curing apparatus of
a is a bottom view of yet another embodiment of a fiber optic-transmitted curing apparatus of this invention.
b is a front view of the curing apparatus of
c is a perspective view of the curing apparatus of
d is a side view of the curing apparatus of
a is a bottom view of still yet another embodiment of a fiber optic-transmitted curing apparatus of this invention.
b is a front view of the curing apparatus of
c is a perspective view of the curing apparatus of
d is a side view of the curing apparatus of
a is a bottom view of yet another embodiment of a fiber optic-transmitted curing apparatus of this invention.
b is a front view of the curing apparatus of
c is a perspective view of the curing apparatus of
d is a side view of the curing apparatus of
a is a plan view of an exemplary pinning head of this invention.
b is an end view of the pinning head of
c is an end view of the pinning head of
a is a front view of another embodiment of the curing apparatus of this invention.
b is a bottom view of the curing apparatus of
c is a side view of the curing apparatus of
a is a bottom view of an embodiment of a pinning head of this invention.
b is a front view of the pinning head of
c is a top view of the pinning head of
d is a side view of the pinning head of
e is a perspective view of the pinning head of
f is a partial view of the pinning head of
a is a bottom view of another embodiment of a pinning head of this invention deployed between two printing heads.
b is a side view of the pinning head of
c is a perspective view of the pinning head of
d is a front view of the pinning head of
It is understood that the above-described figures are only illustrative of the present invention and are not contemplated to limit the scope thereof.
Each of the additional features and methods disclosed herein may be utilized separately or in conjunction with other features and methods to provide improved devices of this invention and methods for making and using the same. Representative examples of the teachings of the present invention, which examples utilize many of these additional features and methods in conjunction, will now be described in detail with reference to the drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Therefore, combinations of features and methods disclosed in the following detailed description may not be necessary to practice the invention in the broadest sense and are instead taught merely to particularly describe representative embodiments of the invention.
A person of ordinary skill in the art will readily appreciate that individual components shown on various embodiments of the present invention are interchangeable to some extent and may be added or interchanged on other embodiments without departing from the spirit and scope of this invention.
a-1f, 2a-2e show one embodiment of a head assembly 100 of this invention, the head assembly 100 having a pinning head 104 with a pinning head body 105 and a fiber optic cable 106. Present in each fiber optic cable 106 is a plurality of optic fibers 108 to convey radiation such as ultraviolet (UV) light from a light source to a substrate such as a page being printed and on which has been deposited a UV-curing ink during printing. The heads 104 may be formed by injection molding or by first inserting material into a mold into which the optic cables 106 and fibers 108 are positioned previously. The material is then allowed to solidify or to cure to thereby secure the optic cables 106 and fibers 108 in position. As can be seen, the light is transmitted to the head assembly by the fiber optic cable 106 which is round or elliptical in cross section. However, once in the head assembly 100, the light is transmitted to be emitted from ends 110 of the optic fibers into a focused beam having a desired geometrical shape, such as the linear shape shown in
Optionally, a rod optic 112, such as shown in
While not shown, a ball lens or a collimating lens may be present over the terminal fiber optic configuration to further provide the desired pattern, intensity, and uniformity of illumination. Additionally, a ball lens, e.g., 20 mm (+/−1%, 5%, 10%), or collimating lens may be present proximate (such as downstream from) the light source to focus or collimate the light entering the fiber optic cable 106. A person of ordinary skill in the art will realize that the desired geometric shape for the emitted focused light may include rectangular and square shapes, as well as round and oval, the configuration of these shapes being determined by factors such as the amount of light needed, the type of ink being cured, and the amount of time or speed necessary to cure the ink being deposited on the substrate.
Referring to
Another example of a curing assembly of this invention is shown in
a-6d show still another embodiment of the curing assembly of this invention at 160, the curing assembly 160 including light sources 162, 163, lens assemblies 164, 165, and fiber optic cables 166, 167 which transmit light to fiber optic cable 168. Light is then transmitted through fiber optic cable 168 to a pinning heat 104. In this embodiment, optic fibers from the fiber optic cables 166, 167 extend continuously through fiber optic cable 168 and terminate in pinning head 104 as shown and described above. Differing peak wavelengths of UV light could be emitted from the light sources 162, 163.
a-7d depict yet another embodiment of the curing assembly of this invention at 170. The curing assembly 170 has a light source 172, a lens assembly 174, fiber optic cables 176, 178, 179, and two pinning heads 104.
Separate optic fibers from fiber optic cable 176 extend into one of fiber optic cables 178, 179 and terminate in one of heads 104 as described above.
a-8d show still yet another embodiment of the curing assembly of this invention at 180 and include light sources 182, 183, 184, lens assemblies 186, 187, 188, fiber optic cables 190, 191, 192, 193, and a pinning head 104. Individual optic fibers from each of the fiber optic cables 190, 191, 192 extend through fiber optic cable 193 and terminate in pinning head 104 as described above.
a-9d depict still another embodiment of the curing assembly of this invention at 200, which has a light source 202, lens assembly 204, fiber optic cables 206, 207, 208, 209, and three pinning heads 104. In this embodiment, individual optic fibers from fiber optic cable 206 extend through one of fiber optic cables 207, 208, 209, and terminate in one of the three heads 104.
Referring to
The embodiments with a plurality of light sources can provide a plurality of light spectra with differing peak wave lengths for curing a blend of inks with differing wave length requirements. Multiple light sources can also be combined to provide a greater intensity of light or the same intensity of light on a longer print head. A single light source (e.g., LED) can be used to illuminate two or more heads with corresponding reduced intensity, but effecting a longer cure length or enabling multiple curing positions. Accordingly, the curing assembly of this invention includes one or a plurality of both light sources and pinning heads. While not depicted, curing assemblies with pluralities of both light sources and pinning heads are contemplated to be included in this invention.
In certain embodiments, the pinning heads of this invention have no electronics. There is accordingly, no necessity to cool these pinning heads. Thus, these pinning heads have no cooling apparatus. Cooling apparatus may be present within or proximate the light source. However, the light source is remote from the instant pinning head(s). Because there are no electronics to cool in the pinning head and because the light source is remote, there is no air turbulence generated by the pinning heads of this invention. Therefore, ink patterns being deposited by ink jet heads 130, 132 (see
A curing assembly 240 shown in
a-12f show a pinning head 104 of this invention, in which the optic fibers 108 emit, e.g., UV light. The emitted light is then focused or refracted by a rod optic 112 before being directed at a substrate for curing.
a-13d depict a pinning head 250, which has a pinning head body 252 and a plurality of optic fibers 108 positioned by the pinning head body 252. The optic fibers, before being present in the pinning head body 252 are bundled in a fiber optic cable 106. Due in part to the lack of cooling apparatus, the distal end 254 of the pinning head body 252 can be extremely small in cross sectional dimension. For example, the exemplary distal end 254 depicted has a depth of 0.197 (+/−1%, 5%, 10%) inch and the optical fibers may be 0.118 (+/−1%, 5%, 10%) inch in depth. The pinning head 250 is shown deployed between two printing heads 256,258, which may be about 2.402 inches in height and 4.921 inches in length. However, any dimension for the printing heads may be utilized to achieve the desired pattern of ink of a substrate being printed.
In the context of this invention and as enabled herein, one typical ink-curing application occurs within an ink printing device. In the ink printing device, ink is dispensed by multiple ink-dispensing units, which are applying various colors or treatments to the substrate. The precision of application and quality of this process is greatly affected by the distance between the dispensing units. As the distance between dispensing units decreases, the better the quality of printing will be enhanced.
Thus, the device of this invention greatly reduces the distance between the printing units and improves the overall process and printing quality dramatically. The present device also allows flexibility of application by increasing or decreasing intensity as needed by the process without adversely impacting required space.
A suitable fiber optic cable will efficiently transmit UV light from the light source through the lens to the substrate. Acceptable materials for fiber optic cable of this invention include silica, fluorozirconate, fluoroaluminate, phosphate, and chalcogenide glasses, and low loss plastic optical fibers as well as crystalline materials such as sapphire. Regarding silica materials, a high OH concentration has been found to be suitable for UV transmission. Suitable materials for some fiber optic embodiments include Poly(methyl methacrylate) (PMMA), polystyrene and BK-7. Suitable lenses may include sapphire and BK-7. Specific materials suitable for certain embodiments include borosilicate and fused silica.
While the instant heads are contemplated to include aluminum, other materials such as polymers, wood, or metals could be used as well. Suitable synthetic resins may be used for the heads of this invention and a person of ordinary skill in the art will readily recognize that other synthetic resins may be suitable for a given embodiment of this invention. Other suitable synthetic resins may be found in the Handbook of Plastics, Elastomers, and Composites, Charles A. Harper, Editor in Chief, Third Edition, McGraw-Hill, New York, 1996, hereby incorporated by reference.
A suitable lens assembly for this invention is designed to collect and collimate the light leaving the light source to deliver maximum curing effect to the substrate. The first stage of the lens array or assembly may collect the light, which may leave the light source with a lambertian angular distribution. The second stage of the lens array or assembly then focuses the collected light onto the fiber bundle, with an incident angle less than the critical angle. The lens may be designed in such a way as to create a focused image of the light source on the fiber bundle, delivering uniformly distributed light onto the curing substrate. An alternative embodiment is to use a molded optic lens, which has a complex three-dimensional geometric shape. This lens would accomplish collection, collimation, and focusing with a single lens, instead of a lens assembly or plurality of lenses. Optics could also be used between the light-emitting head and the substrate to further improve printing performance.
Thus, the present invention provides UV light to cure ink deposited on a substrate remote to the LED or other device used to emit UV spectrum electromagnetic radiation. Being remotely configured allows for light to be delivered to desired locations without allocating space for the LEDs themselves. Additionally, heat can be removed remotely as well to reduce or eliminate undesirable effects of heat on ink jets, substrate, or ink being cured.
While UV-curable inks are commonly used in printing, some inks cure more efficiently when exposed to UV light having specific spectral compositions. Accordingly, differing spectra can be delivered onto substrate being printed. For example a spectrum having differing wavelength compositions could be emitted from each of the heads to enable more thorough curing for inks being used.
The larger LED chips contemplated for use in this invention generate desired light spectra over a larger area than previously possible. Accordingly, the optic fiber bundle is dimensioned and has a geometry sufficient for essentially all generated light to be transmitted by the optic fibers.
Because numerous modifications of this invention may be made without departing from the spirit thereof, the scope of the invention is not to be limited to the embodiments illustrated and described. Rather, the scope of the invention is to be determined by the appended claims and their equivalents.
This is a continuation-in-part of U.S. patent application Ser. No. 13/940,088, filed 11 Jun. 2013, which, in turn, claims priority under 35 U.S.C. §119 (e) to U.S. Provisional Application No. 61/670,144, filed 11 Jul. 2012, each of the foregoing patent applications hereby incorporated by reference.
Number | Date | Country | |
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Parent | 13940088 | Jul 2013 | US |
Child | 14013257 | US |