Patent Application
20220144573
The present invention relates generally to the field of ink jet printers, and more particularly to the construction of a conveyor apparatus used in connection with such printers to reduce print defects during advancement of a printable substrate in high resolution color printing applications.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Flexible conveyor belts are often used to move parts underneath arrays of printheads for printing. Print quality of color printing is dependent upon the conveyor moving the printable substrate in a straight line. Any deviation from straight-line motion results in color-to-color registration error that reduces print quality. Inkjet print heads are now available with much higher resolution than previously, which places increasingly stringent accuracy requirements on color-to-color registration.
Meeting these requirements with flexible conveyor belts can be difficult or impossible. Flexible conveyor belts have a tendency to wander during operation causing misalignment and registration errors with the printable substrate. The effect of thermal expansion on the system is also an important factor that must be mitigated. During operation, the equipment will likely begin at a relatively cool ambient temperature. As operation continues, the conveyor system can fluctuate in temperature causing thermal expansion and contraction, thus leading to tracking/printing errors. If unaccounted for, the effect of expansion and contraction in the system can have a negative impact on belt timing, tracking, tension, and surface flatness. Other outside forces may also be cause for tracking errors in such belt conveyor systems.
Accordingly, there is a distinct need in the field of high resolution color inkjet printing for a conveyor system which will help resolve the misalignment and print registration deficiencies of conventional flexible belt printers. The rigid segmented conveyor system described herein helps to resolve these problems and can be made as accurate as required for the new generation of high-resolution print heads.
In the present invention, the conveyor platform upon which a printable substrate is carried is comprised of a plurality of separate individual rigid conveyor track segments which are connected together but independently movable relative to each other. The individual conveyor track segments are connected to a chain (or timing belt) that moves them around the conveyor path. Each track segment includes one or more rotatable wheel bearings connected to opposite transverse sides thereof which effect precise guided movement of the track segment along the path of conveyance. While being moved around the conveyor path, the wheels on opposite sides of each conveyor track segment are constructed to engage mating guideways that are fixed to the frame of the conveyor. This stationary guideway system restricts the motion of each conveyor track segment to precisely a straight line at the correct height.
In one preferred embodiment of the present conveyor system, a generally V-shaped feature of each wheel bearing assembly engages with a corresponding mating V-shaped guide feature of the stationary guideway system. Of course, other possible mating wheel and track configurations are certainly conceivable without departing from the invention herein. The wheel(s) at one side of each conveyor track segment are free to rotate only, i.e., these wheels are fixed to the conveyor track segment in the axial direction. The wheel(s) on the other end of each conveyor track segment are free to move axially as well as rotationally. This allows the motion of each conveyor track segment to be precisely controlled without over-constraining each conveyor track segment.
Each rigid conveyor track segment is also preferably constructed as a substantially hollow shell with opposing end blocks for mounting the respective wheel bearings. A plurality of minor vent openings formed in the upper surface of each track segment upon which the printable substrate is carried communicate with the hollow interior thereof. The underside of each track segment also includes one or more openings which are adapted to register in substantially sealed relation during conveyance with a vacuum system that is connected to an underside portion of the conveyor system. In this manner, as the printable substrate advances along the conveyor, suction created by the vacuum system within each conveyor segment helps to hold the printable substrate in its proper precise location upon the conveyor.
The foregoing and additional features and advantages of the present invention will be more readily apparent from the following detailed description. It should be understood, however, that the description and specific examples herein are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
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While the present embodiment discloses the use of two axially fixed wheel bearing assemblies 18 on one side and one axially free wheel bearing assembly 14 on the other side, other configurations of the wheel bearing assemblies 14 and 18 are certainly conceivable without departing from the invention herein. For instance, it is possible to have two or more axially free wheel bearing assemblies 14 on one side of each conveyor track 4 and a single axially fixed wheel bearing assembly 18 on the other side. It is also possible to have multiple wheel bearing assemblies 14 and/or 18 on opposite sides of each track segment 4.
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In operation, while being moved around the conveyor path, the wheels 10 and 11 of each conveyor track segment 4 become engaged with the track of guideway 13 which is fixed on each transverse side of the conveyor frame 6. The stationary guideway 13 restricts the motion of each conveyor track segment 4 to precisely a straight line at the correct height. The V-shaped feature in each wheel 10 and 11 engages with the V-shaped protrusion of the stationary guideway 13. The wheels 11 at one side of each conveyor track segment 4 are free to rotate only, as the wheels 11 are fixed to the conveyor track segment 4 in the axial direction. The wheels 10 on the other end of each conveyor track segment 4 are free to move axially as well as rotationally. This allows the motion of each conveyor track segment 4 to be precisely controlled without over-constraining each conveyor track segment 4.
For additional control and precision alignment, the present segmented conveyor system 2 also incorporates an optional vacuum system 24 to help hold and maintain proper positioning of the printable substrate 1 upon the conveyor track segments 4 during operation. As noted previously and shown in
Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, “below”, “top”, “bottom”, “upward”, “downward”, “rearward”, and “forward” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context.
When introducing elements or features and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
The disclosure herein is intended to be merely exemplary in nature and, thus, variations that do not depart from the gist of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure, which comprises the matter shown and described herein, and set forth in the appended claims.
| Number | Date | Country | |
|---|---|---|---|
| 63111181 | Nov 2020 | US |
