Patent Application
20110030569
The present invention relates in general to a print press system and a method for printing an electronic circuit on a material (e.g., glass substrate, plastic film, and plastic film-glass substrate laminate). In exemplary applications, the print press system can print an electronic circuit on a material to form, for instance, a flexible Liquid Crystal Display, a retail point of purchase sign and an e-book.
Manufacturers have been trying to improve the performance of the current printing technology to enable electronic circuits with small features to be printed on a piece of material. In particular, manufacturers would like to improve the current printing technology which uses a sequence of print cylinder stations to enable higher resolution and higher precision for layer to layer registration so that electronic circuits with small features can be effectively printed onto a material. For instance, the current printing technology which uses print cylinder stations can print features onto a material with a layer to layer registration of approximately ±125 μm. Thus, any enhancement in the current printing technology would be desirable to help improve the printing of electronic circuits with small features onto a material.
In one aspect, the present invention provides a print cylinder station for printing at least part of an electronic circuit on a material. The print cylinder station includes: (a) a base; (b) a plurality of adjustable mounts located on the base; (c) at least one component, where each component (e.g., roller support platform, doctor blade system) is located on one or more of the adjustable mounts; (d) a pair of bearings, where each bearing is located on one or more of the adjustable mounts; and (e) a print cylinder rotatably supported between the pair of bearings, where the one or more of the adjustable mounts associated with the pair of bearings and the one or more of the adjustable mounts associated with each component have been positioned to ensure that each component is substantially aligned with the print cylinder. In addition, the print cylinder station may include a pressure cylinder, a temperature control system, a pressure sensor, a print cylinder registration sensor, and a material registration sensor.
In another aspect, the present invention provides a print press system for printing an electronic circuit on a material. The print press system includes a main control system which operatively controls a lead print cylinder station and at least one subsequent print cylinder station. The lead print cylinder station and subsequent print cylinder station(s) are aligned next to one another such that the material is able to be transported from the lead print cylinder station to each of the subsequent print cylinder station(s) while the electronic circuit is printed on the material. Each print cylinder station includes: (a) a base; (b) a plurality of adjustable mounts located on the base; (c) at least one component, where each component (e.g., roller support platform, doctor blade system) is located on one or more of the adjustable mounts; (d) a pair of bearings, where each bearing is located on one or more of the adjustable mounts; and (e) a print cylinder rotatably supported between the pair of bearings, where the one or more of the adjustable mounts associated with the pair of bearings and the one or more of the adjustable mounts associated with each component have been positioned to ensure that each component is substantially aligned with the print cylinder. In addition, each print cylinder station may include a pressure cylinder, a temperature control system, a pressure sensor, a print cylinder registration sensor, and a material registration sensor.
In yet another aspect, the present invention provides a method for printing an electronic circuit on a material. The method including the steps of: (a) setting-up a lead print cylinder station and at least one subsequent print cylinder station; and (b) aligning the lead print cylinder station and the subsequent print cylinder station(s) next to one another such that the material is able to move from the lead print cylinder station to each of the subsequent print cylinder(s) while the electronic circuit is printed on the material. Each print cylinder station includes: (a) a base; (b) a plurality of adjustable mounts located on the base; (c) at least one component, where each component (e.g., roller support platform, doctor blade system) is located on one or more of the adjustable mounts; (d) a pair of bearings, where each bearing is located on one or more of the adjustable mounts; and (e) a print cylinder rotatably supported between the pair of bearings, where the one or more of the adjustable mounts associated with the pair of bearings and the one or more of the adjustable mounts associated with each component have been positioned to ensure that each component is substantially aligned with the print cylinder. In addition, each print cylinder station may include a pressure cylinder, a temperature control system, a pressure sensor, a print cylinder registration sensor, and a material registration sensor.
Additional aspects of the invention will be set forth, in part, in the detailed description, figures and any claims which follow, and in part will be derived from the detailed description, or can be learned by practice of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as disclosed.
A more complete understanding of the present invention may be had by reference to the following detailed description when taken in conjunction with the accompanying drawings wherein:
Referring to
In operation, the lead print cylinder station 106 prints a portion of the electronic circuit 102 on the bottom side of the bare material 104. The first subsequent print cylinder station 108a then prints another portion of the electronic circuit 102 over or adjacent to the first portion of the electronic circuit 102. The second subsequent print cylinder station 108b then prints another portion over or adjacent to the two previous portions of the electronic circuit 102. The third subsequent print cylinder station 108c prints another portion over or adjacent to the three previous portions to form the electronic circuit 102. In this example, the electronic circuit 102 is printed on the bottom surface of the material 104 which can be a glass substrate 104, a plastic film 104, or a plastic film-glass substrate laminate 104. For clarity, a description about well known components such as, for example, tension systems, drying systems, inspection systems, take-up systems have not been discussed herein.
Referring to
In this example, the print cylinder stations 106, 108a, 108b and 108c each have their own base 110 on which there is located multiple kinetic mounts 112 (e.g., exact constraint mounting features 112). Each component 114 (e.g., roller support platform 114a, doctor blade system 114b) is located on top of one or more of the multiple kinetic mounts 112. Each bearing 116a and 116b is located on top of one or more of the multiple kinetic mounts 112. The print cylinder 118 is rotatably supported between the pair of bearings 116a and 116b. The kinetic mounts 112 have been adjusted and positioned to ensure that each component 114 is substantially aligned with the print cylinder 118. The pressure cylinder 120 is positioned above the print cylinder 118 so the material 104 can be drawn there between while printing at least a portion of the electronic circuit 102 on the material 104. The temperature control system 122 is adapted to circulate a media within the print cylinder 118 to control a temperature of the print cylinder 118. The pressure sensor 124 is adapted to monitor a force (nip force) applied by the print cylinder 118 and the pressure cylinder 120 onto the material 104 while at least part of the electronic circuit 102 is printed on the material 104. The print cylinder registration sensor 126 can be an optical sensor that is adapted to respectively monitor registration lines 130 engraved on the print cylinder 118. The material registration sensor 128 can be an optical sensor that is adapted to monitor registration lines 132 and trapezoid(s) 133, 137a, 137b (or any shape that has an angled edge) printed on the material 104.
In this example, the print cylinder 118 of lead print cylinder station 106 has engraved registration lines (not shown) and an engraved trapezoid (not shown) that respectively print the registration lines 132 and the registration trapezoid 133 on the material 104 (see
The print cylinder stations 106, 108a, 108b and 108d (for example) starting with the print cylinder's bearings 116a and 116b and working outward may be constructed as described below.
Print Cylinder's Bearings 116a and 116b
The print cylinder 118 may be radially supported by a pair of air or hydrostatic bearings 116a and 116b to achieve minimal run-out and maximum performance of the print cylinder 118. The air or hydrostatic bearings 116a and 116b offer a lower run-out and higher stiffness when compare to lower grade bearings, thus resulting in greater performance. In particular, with the lower run-out, the features of the circuit 102 can be printed more accurately on the material 104 and a better layer to layer registration of the different layers of the electronic circuit 102 on the material 104 can be achieved by the print cylinder stations 106, 108a, 108b, and 108b. Plus, with the higher stiffness, the forces applied when transferring a printed image for the electronic circuit 102 from the print cylinder 118 to the material 104 would have less impact on the print cylinder 118 and the bearings 116a and 116b. It is estimated that the run-out can be improved from 10 um to less than 1 um and the stiffness can be improved from 175,000 n/mm to 525,000 n/mm by utilizing the air or hydrostatic bearings 116a and 116b. If desired, the pressure cylinders 120 may also be mounted with a pair of air or hydrostatic bearings which can help improve the consistency of the nip force with the print cylinders 118 and therefore help improve the transfer of the ink to the material 104. Some examples of different types of ink that can be used include conductive inks (both silver based and clear conductors, such as PEDOT:PSS), dielectric inks (i.e., PVP, PMMA) and semi-conductive (lisicon™) inks.
Kinetic Mounts 112
The kinetic mounts 112 may be used to support and accurately locate the print cylinder 118 (located on the bearings 116a and 116b) and the various components 114 including, for instance, the roller support platform 114a and the doctor blade system 114b. The kinematic mounts 112 maintain a precise level tolerance alignment with high performance repeatability when locating and supporting the print cylinder 118, the roller support platform 114a, and the doctor blade system 114b to achieve a high level of printing accuracy. In this example, the roller support platform 114a can be used to support multiple or various types of rollers 134 (e.g., impression rollers, analox rollers, gravure print rollers, and other rollers), the pressure cylinder 120, the temperature control system 122, the pressure sensor 124, the print cylinder registration sensor 126, the material registration sensor 128, and other associated equipment (see
Temperature Control System 122
The temperature control system 122 may be used to help minimize the performance impact due to temperature gradients within the system or individual components or temperature fluctuations within the system or individual components during the printing process and thereby maximize performance by heating or cooling the print cylinder 118, the pressure cylinder 120 and/or the other associated rollers 134 to maintain an even temperature distribution throughout the system or components and a constant temperature level throughout the process. For instance, the temperature control system 122 may utilize rotary unions which can be added to the print cylinder 118, the pressure cylinder 120 and/or the other associated rollers 134 so that coolant or heating media can be circulated therein to achieve the desired temperature profile. The temperature control system 122 may also be used to maintain a uniform and constant temperature of a roller 134, to heat a roller 134, to help dry or set an ink, or to cool a roller 134 to lower the temperature of the material 104 prior to printing. In addition, the temperature control system 122 can be used to help maintain a constant temperature of the bearing media within the hydrostatic bearings 116a and 116b. The main control system 103 may control and monitor the temperature control system 122. It is estimated that the temperature control system 122 can be designed and built to maintain the temperature of the print cylinder 118 to within about 0.3° C. of a desired printing temperature, which for instance (based on the coefficient thermal expansion (CTE) of the print cylinder 118) can maintain a growth of 1 um within an A4 size print pattern. Plus, the temperature control system 122 can be designed and built to minimize a temperature variation of the material 104 as it passes through the multiple print cylinder stations 106, 108a, 108b and 108b by maintaining the temperature variation of the material 104 during the printing process to within about 1.0° C. of the desired printing temperature. In other words, the growth of an A4 glass substrate would be limited to approximately 1 micron by maintaining the temperature within about 1.0° C. Maintaining the print cylinder and material at a constant and uniform temperature minimizes variations in print position and size, providing for more accurate circuit placement, size, shape and registration.
Pressure Sensor 124
The pressure sensor 124 may be used to monitor a force applied by the print cylinder 118 and the pressure cylinder 120 onto the material 104 while at least part of the electronic circuit 102 is printed on the material 104. In this application, the pressure sensor 124 would be installed in a manner that it measures the force applied to the material 104 as it passes through the nip formed by the print cylinder 118 and the pressure cylinder 120. Thus, the main control system 103 can receive active feedback on the amount of pressure and force applied to the material 104 during the printing process. The main control system 103 can use the pressure force measurement to fine tune the gap between the print cylinder 118 and the pressure cylinder 120 so as to maintain a constant nip force. For instance, the main control system 103 may adjust the nip force between the print cylinder 118 and the pressure cylinder 120 by controlling a mechanical device (not shown), such as a screw drive, hydraulic device, or pneumatic device, upon which the bearings for one of the print cylinder 118 or the pressure cylinder 120 are mounted. This nip force control reduces variations in print size and weight caused by variations in print pressure (nip force), resulting in a more consistent and uniform transfer of ink from the print cylinder 118 to the material 104. It is estimated that the main control system 103 and the pressure sensor 124 can control the nip force to a level of 10's of grams within a desired nip/print force, which helps to improve the consistency of the ink lay down thickness on the material 104.
Closed-Loop Control, Registration Lines 132 and Trapezoids 133, 137a and 137b
To enable an enhanced active alignment capability, the lead print cylinder 118 has registration lines (not shown) and a trapezoid (not shown) engraved thereon which are used to respectively print the registration lines 132 and the registration trapezoid 133 on the bottom side of the material 104. The down-stream print cylinder stations 108a, 108b and 108c may use their respective print cylinder registration sensor 126 to monitor the engraved registration lines 130 on their respective print cylinders 118. In addition, the down-stream print cylinder stations 108a, 108b and 108c may use their respective material registration sensor 128 to monitor the printed registration lines 132 and the printed registration trapezoids 133, 137a and 137b on the material 104. Then, the main control system 103 may use the monitored registration marks 130, 132 and the monitored registration trapezoids 133, 137a and 137b to compensate for alignment, radial and/or linear (with web and cross web) misalignments of the material 104 as well as velocity control in each of the print cylinder stations 106, 108a, 108b and 108c.
In one exemplary control scheme, the main control system 103 can use the monitored registration marks 130 and 132 to compensate for misalignments of the material 104 in the direction of the moving web as well as velocity control in each of the print cylinder stations 106, 108a, 108b and 108c. The main control system 103 can use the angled side of the monitored registration trapezoids 133, 137a and 137b to compensate for misalignments of the material 104 in the cross web direction. In particular, the main control system 103 can use the leading edge of the monitored registration trapezoids 133, 137a and 137b to determine registration in the direction of conveyance and the distance from the leading to the trailing edge of the monitored registration trapezoids 133, 137a and 137b is used to determine registration in the across direction. In this way, each of the down-stream print cylinders 118 can be positioned and rotated to match to the moving material 104. In effect, a trapezoid shape or any shape with an angled edge can be printed on the moving material 104 and then the down-stream print cylinder stations 108a, 108b and 108c may implement an imaging system to help control the respective down-stream print cylinders 118 to match the moving material 104. Alternatively, the main control system 103 may use just the monitored registration trapezoids 133, 137a and 137b to control velocity and compensate for misalignments of the material 104 in the web direction (by using the straight side of the trapezoids 133, 137a and 137b) and to compensate for misalignments of the material 104 in the cross web direction (by using the angled side of the registration trapezoids 133, 137a and 137b). It is estimated by implementing this type of control scheme or a similar control scheme that the active alignment of the print cylinders 118 can be improved from ±250 um to less than ±5 um, providing for improved circuit element placement accuracy at each print station 106a, 108a, 108b and 108c and improved registration between the print stations 106a, 108a, 108b and 108c.
Thus, the main control system 103 can interact with the various print cylinder registration sensors 126 and the various material registration sensors 128 and then control the alignment and rotational speeds of the various print cylinders 118 to match the moving material 104 and accurately match/register the print cylinders 118 with circuit elements 102 already printed on the material 104. In one example, the main control system 103 has one or more processors 136 and at least one memory 138 (storage 138) that includes processor-executable instructions where the one or more processors 136 are adapted to interface with the memory 138 and execute the processor-executable instructions to interface with and control the various mechanical device(s) (variable speed drives-motors, alignment devices etc.) associated with the print cylinders 118 and possibly the pressure cylinders 120 to ensure that the position and rotational speed of each down-stream print cylinder 118 is matched to the moving material 114. The one or more processors 136 and the at least one memory 138 can be implemented, at least partially, as software, firmware, hardware, or hard-coded logic.
Referring to
Referring to
This engraving process in which the print cylinder 118, the bearings 116a and 116b and the corresponding kinetic mounts 112 are all placed as a unit within the engraving device 502 and then moved as a unit and mounted within the print station 106a, 108a, 108b and 108c is a marked-improvement over the traditional engraving process where only the print cylinder 118 itself would be moved between bearings located within the engraving machine and different bearings located within the print station. In particular, this engraving process ensures minimal run-out variation between the engraving process and the print press process by preventing the creation of a wobble in the motion of the print cylinder 118 while it is used in printing operation that results from the print cylinder 118 being mounted in different bearings and on different mounts during printing than during engraved. In addition, this engraving process maximizes the print resolution, alignment and registration during the print process. Plus, this engraving process enables one to alternatively use ordinary mounts and not the specialized kinetic mounts 112 (e.g., exact constraint mounting features 112) if desired and still benefit from an improvement over the traditional engraving process. It is estimated by implementing this change to the engraving process that the maximum run-out can be improved from 25 um to less than 1 um.
In view of the foregoing discussion, it should be appreciated by those skilled in the art that the print press system 100 and the print cylinder stations 106, 108a, 108b and 108c address a need for improved performance in the current printing technology to enable printed electronic circuits 102 that require higher resolution to be manufactured in a continuous format on a material 104 (e.g., glass substrate 104, plastic film 104, plastic film-glass substrate laminate 104). In particular, the print press system 100 and the print cylinder stations 106, 108a, 108b and 108c can improve the print resolution and layer to layer registration of the different layers of the electronic circuit 102 from ±125 μm to ±25 μm which is desirable when printing electronic circuits 102 with small features on a material 104 in a continuous format. This improvement is made possible by one or more of the following features:
Improved alignment and velocity control is made possible by engraving a reference scale (optional) and a trapezoid (or any shape with an angled edge) on the leading print cylinder 118, printing the reference scale 132 (optional) and the trapezoid 133 (or any shape with an angled edge) on the material 104. And, engraving a trapezoid 135a (or any shape with an angled edge) on the down-stream print cylinders 118 and printing the trapezoids 137a and 137b (or any shape with an angled edge) on the material 104. Plus, locating the material registration sensor 128 on each of the subsequent print cylinder stations 108a, 108b and 108c.
As described, the print cylinder stations 106, 108a, 108b and 108c can have one or more of the following features such as, the print cylinder's bearings 116a and 116b, the engraving of the print cylinder 118, the alignment of the print cylinders 118 and associated components, the temperature control of the print cylinders 118, the force measurement, and the ability to print a reference scale on the material 104, and the use of a scale for layer to layer alignment and synchronizing down-stream print cylinders 118 to the match the moving material 104. In exemplary applications, the print press system 100 can be used to print an electronic circuit 102 on a material 104 (e.g., glass substrate 104, plastic film 104, plastic film-glass substrate laminate 104) to form, for instance, a flexible Liquid Crystal Display, a retail point of purchase sign and an e-book.
Although one embodiment of the present invention has been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it should be understood that the invention is not limited to the disclosed embodiment, but is capable of numerous rearrangements, modifications and substitutions without departing from the spirit of the invention as set forth and defined by the following claims. Plus, it should be appreciated that the reference to the “present invention” or “invention” used herein relates to exemplary embodiments and not necessarily to every embodiment that is encompassed by the appended claims.
