Method for producing a heating system on a 3D plastic window

Abstract

A method for producing a heating system on a 3D plastic window, such as a car window. The heating system having an electric heat conductor structure with at least two bus bars and a grid line pattern with a plurality of grid lines. The method having: a step in which the two bus bars, made of a first electrically conductive paste are screen-printed onto the window by a displaceable squeegee; a step in which the grid line pattern is applied onto the window such that it respectively overlaps the two bus bars with at least one second electrically conductive paste which has a greater electrical resistance than the first electrically conductive paste, and a final step in which the two bus bars and the grid lines overlapping these bus bars are at the respective overlapping points electrically connected into the electric heat conductor structure by means of electrical connectors.

Claims

1. A method for producing a heating system on a 3D plastic window, said heating system comprising an electric heat conductor structure consisting of at least two bus bars and a grid line pattern with a plurality of grid lines, the method comprising: a step, in which the at least two bus bars are respectively screen-printed onto the 3D plastic window by at least one displaceable squeegee with screen-printing ink consisting of a first electrically conductive paste; a step, in which the grid line pattern is applied onto the 3D plastic window such that it respectively overlaps the at least two bus bars with at least one second electrically conductive paste which has a greater electrical resistance than the first electrically conductive paste; and a final step, in which the at least two bus bars and the grid lines overlapping these bus bars are at the respective overlapping points electrically connected into the electric heat conductor structure by electrical connectors, wherein at least one of the grid line pattern and the at least two buss bars are applied onto the 3D plastic window by two squeegees that operate in different directions.

2. The method according to claim 1, wherein the step in which the bus bars are applied onto the 3D plastic window is offset in time in reference to the step in which the grid line pattern is applied onto the 3D plastic window.

3. The method according to claim 1, wherein the step in which the bus bars are applied onto the 3D plastic window is carried out prior to the step in which the grid line pattern is applied onto the 3D plastic window.

4. The method according to claim 1, wherein the step in which the grid line pattern is applied onto the 3D plastic window is carried out prior to the step in which the bus bars are applied onto the 3D plastic window.

5. The method according to claim 1, wherein the grid line pattern is screen-printed onto the 3D plastic window by means of at least one displaceable squeegee.

6. The method according to claim 1, wherein the bus bars are applied onto the 3D plastic window by means of at least one first displaceable squeegee and/or the grid lines of the grid line pattern are applied by means of at least one second displaceable squeegee.

7. The method according to claim 1, wherein at least one of: the grid line pattern and the at least two bus bars are applied onto the 3D plastic window by one squeegee that prints in two directions.

8. The method according to claim 1, wherein the grid line pattern is applied onto the 3D plastic window by means of dispensing.

9. The method according to claim 1, wherein the grid line pattern is applied onto the 3D plastic window by utilizing a digital inkjet printer.

10. The method according to claim 1, wherein the at least two bus bars are applied onto the 3D plastic window by a squeegee that prints in two directions and/or by two squeegees that operate in different directions.

11. The method according to claim 1, wherein the at least two bus bars of the heat conductor structure are simultaneously applied on the left and on the right side of the 3D plastic window in the region of the grid line pattern due to the combination of a feed motion and a rotational motion of the at least one squeegee.

12. The method according to claim 1, wherein the screen-printing of the heat conductor structure consisting of the at least two bus bars and the grid lines overlapping these bus bars is respectively carried out with one of two screens that are used offset in time, wherein the at least two bus bars are applied onto the 3D plastic window along the edges of the latter with the corresponding screen and with separately displaceable squeegees.

13. The method according to claim 1, wherein the two screens, by which the heat conductor structure consisting of the bus bars and the grid lines overlapping these bus bars is screen-printed onto the 3D plastic window, are inserted into an upper unit of a screen-printing machine in succession.

14. The method according to claim 1, wherein two screens, each of which is inserted into the upper unit of the screen-printing machine or guided by a robot or position-controlled for the respective application of one of the at least two bus bars, are used for screen-printing the at least two bus bars of the heat conductor structure to be produced onto the 3D plastic window.

15. The method according to claim 1, wherein the at least one displaceable squeegee used for applying the grid line pattern onto the 3D plastic window is a squeegee that prints in two directions, and starting at the beginning of the first grid line of the grid line pattern, prints the second electrically conductive paste onto the 3D plastic window in the feed direction such that the first grid line of the grid line pattern is formed, wherein the squeegee then carries out a rotational motion after it reaches the end of the first grid line of the grid line pattern referred to the feed direction and subsequently prints the second electrically conductive paste onto the 3D plastic window in the direction extending opposite to the feed direction such that the second grid line of the grid line pattern is formed, wherein this process is repeated until the complete grid line pattern is formed on the 3D plastic window.

16. The method according to claim 1, wherein the at least two bus bars and the grid lines of the grid line pattern are joined at the overlapping points by a conductive adhesive or by soldering.

17. A method for producing a heat conductor system on a 3D plastic window, said heat conductor system comprising an electric heat conductor structure consisting of at least two bus bars and a grid line pattern with a plurality of grid lines, the method comprising: a step, in which the at least two bus bars and the grid lines of the grid line pattern are respectively screen-printed onto the 3D plastic window such that they overlap one another by means of two squeegees that operate in different directions with screen-printing ink consisting of only one electrically conductive paste; and a subsequent step, in which the at least two bus bars and the grid lines overlapping these bus bars at the respective overlapping points are electrically connected into the electric heat conductor structure by means of electrical connectors.

18. The method according to claim 17, wherein the screen-printing of the at least two bus bars and the grid line pattern with screen-printing ink in the form of the silver paste is carried out continuously by means of a displaceable squeegee capable of printing in opposite directions, wherein this squeegee prints the grid lines of the grid line pattern onto the 3D plastic window starting from the left or the right side with a respective rightward or leftward directed feed motion in a region with less curvature of the 3D plastic window for the grid line pattern, and wherein the feed motion of said squeegee respectively transforms into a rotational and pivoting motion and the squeegee continuously screen-prints one of the two respective bus bars onto the 3D plastic window such that it overlaps the grid lines of the applied grid line pattern in regions with more significant curvature of the 3D plastic window for the two bus bars.

19. The method according to claim 18, wherein the transformations from the feed motion of the at least one squeegee to the rotational and pivoting motion or vice versa are program-controlled.

20. The method according to claim 17, wherein two squeegees, which operate in different directions and the feed motions of which respectively need to be transformed into a rotational and pivoting motion, are used instead of the displaceable squeegee capable of printing in opposite directions.

21. The method according to claim 17, wherein after the respective application of the grid lines of the grid line pattern and/or one of the at least two bus bars, it is ensured that the electrically conductive paste printed onto the 3D plastic window can become touch-dry, preferably by means of self-drying, or is thermally cured by means of IR-radiation or UV-radiation, or by means of heat transmission.

22. A system for carrying out a method for producing a heating system on a 3D plastic window, said heating system comprising an electric heat conductor structure consisting of at least two bus bars and a grid line pattern with a plurality of grid lines, the method comprising: a step, in which the at least two bus bars are respectively screen-printed onto the 3D plastic window, preferably on the edges of the latter, by means of at least one displaceable squeegee with screen-printing ink consisting of a first electrically conductive paste, preferably a first silver paste, a step, in which the grid line pattern is applied onto the 3D plastic window such that it respectively overlaps the at least two bus bars with at least one second electrically conductive paste, preferably a second silver paste, which has a greater electrical resistance than the first electrically conductive paste, and a final step, in which the at least two bus bars and the grid lines overlapping these bus bars are at the respective overlapping points electrically connected into the electric heat conductor structure by means of electrical connectors wherein at least one of the grid line pattern and the at least two buss bars are applied onto the 3D plastic window by two squeegees that operate in different directions; and the system comprises at least one supply station for cleaned 3D plastic windows, at least one screen-printing machine that is positioned on the outlet side of said supply station and respectively applies the electric heat conductor structure consisting of the two bus bars and the grid line pattern onto the supplied 3D plastic windows, a paternoster furnace that is arranged parallel to the at least one screen-printing machine, a robot station with at least one robot between the outlet of the screen-printing machine and the inlet of the paternoster furnace, wherein the 3D plastic windows with the electric heat conductor structure printed thereon by means of the screen-printing machine are picked up at the outlet of the latter and inserted into the paternoster furnace opposite to the previous processing direction in order to cure the electric conductor structure printed onto the 3D plastic windows, and a depositing station for the 3D plastic windows with cured electric heat conductor structure, which is arranged downstream of the outlet of the paternoster furnace.

23. The system according to claim 22, wherein a dispensing unit is positioned between the robot station and, e.g., the paternoster furnace, wherein the 3D plastic windows, onto which initially only the two respective bus bars of the electric heat conductor structure are printed in the at least one screen printing machine, are inserted into the inlet of said dispensing unit by means of the at least one robot of the robot station, wherein the grid lines of the grid line pattern are in the dispensing unit applied onto each of the 3D plastic windows inserted therein by means of dispensing such that they overlap the respective bus bars, and wherein the 3D plastic windows, which are respectively provided with the complete heat conductor structure, are picked up and transported to the inlet of the paternoster furnace by means of at least one conveyor belt or at least one additional robot that is respectively positioned between the outlet of the dispensing unit and the inlet of the paternoster furnace.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described below with reference to the drawings. In these drawings:

(2) FIG. 1 shows a schematic block diagram of the steps of an embodiment of the method according to the invention, that only utilizes screen-printing,

(3) FIG. 2 shows a schematic block diagram of a space-intensive embodiment of the system according to the invention, for carrying out the method according to FIG. 1,

(4) FIG. 3 shows a schematic block diagram of a space-saving embodiment of the isystem according to the invention, for carrying out the method according to FIG. 1,

(5) FIG. 4 shows a schematic illustration of the squeegee progression in an embodiment of the method that comprises two steps and in which only one silver paste is used for the bus bars and for the grid lines of the grid line pattern of the electric heat conductor structure to be produced,

(6) FIG. 5 shows a schematic illustration of the squeegee progression in another embodiment of the method, in which different silver pastes are used for the bus bars and for the grid lines of the grid line pattern of the electric heat conductor structure to be produced,

(7) FIG. 6 shows a schematic block diagram of the steps of an embodiment of the method that comprises a combination of screen-printing and dispensing,

(8) FIG. 7 shows a schematic block diagram of a space-intensive embodiment of the system according to the invention, for carrying out the method according to FIG. 6, and

(9) FIG. 8 shows a schematic block diagram of a space-saving embodiment of the system according to the invention, for carrying out the method according to FIG. 6.

EMBODIMENTS

(10) FIG. 1 shows the sequence of steps of an embodiment of the method according to the invention, that only utilizes screen-printing. In this case, cleaned 3D plastic windows 1 being supplied are fed to at least one screen-printing machine 3 by means of a feed device 2, wherein a heat conductor structure consisting of bus bars and grid lines of a grid line pattern is screen-printed onto the 3D plastic windows 1 by means of said screen-printing machine. On the outlet side of the screen-printing machine 3, the printed 3D plastic windows 1 are received by a removal device 4 and fed to a drying furnace 5 in order to cure the printed electric heat conductor structure. After the latter has dried, the 3D plastic windows 1 are placed into a depositing station 6 arranged downstream of the drying furnace 5.

(11) FIG. 2 schematically shows a space-intensive embodiment of a system for carrying out the above-described method, in which the entire machine arrangement is realized in the form of two parallel processing lines due to the relatively long drying zone of the drying furnace 5 on the order of 30 m. In this case, the feed device 2 for the 3D plastic windows 1 and the screen-printing machine 3 arranged downstream thereof are positioned in a first processing line and the removal device 4 in the form of a robot system with at least one robot is positioned between the outlet of the screen-printing machine and the inlet of a first section 7 of the drying zone of the drying furnace 5. A second section 8 of the drying zone of the drying furnace 5, which is longer than the first section 7 of the drying zone, extends with oppositely extending transport direction in the second processing line, wherein the depositing station 6 for depositing the finished 3D plastic windows 1 is arranged in the second processing line downstream of the outlet 9 of the drying furnace 5. The space requirement of this embodiment of the system amounts to approximately 25 mapproximately 7 m.

(12) FIG. 3 schematically shows a space-saving embodiment of the system for carrying out the method, wherein the drying furnace 5 according to FIG. 2 is replaced with a paternoster furnace 12. In this way, the space requirement of the system is reduced to approximately 15 mapproximately 8 m.

(13) FIG. 4 shows an embodiment of the method according to the invention, in which only screen-printing is utilized, wherein this embodiment comprises two steps A (sections number 1-5) and B (sections 6-9) and only one silver paste is used for the bus bars and the grid lines of the grid line pattern of the electric heat conductor structure to be produced. In order to improve the print quality of the electric heat conductor structure on the 3D plastic windows 1, a displaceable squeegee 10 capable of printing in opposite directions or two squeegees that operate in two different directions may be used in this variation of the method.

(14) According to FIG. 4, the displaceable squeegee 10 capable of printing in opposite directions begins the screen-printing of the two bus bars and the grid line pattern with screen-printing ink in the form of the silver paste on the left or the right side in the section 1; 6 with less curvature of the 3D plastic window 1 for the grid line pattern, in which the grid lines of the grid line pattern are continuously printed onto the 3D plastic window 1 with a respectively rightward or leftward directed feed motion. In the sections 5; 9 with more significant curvature of the 3D plastic window 1 for the two bus bars, the feed motion of the squeegee 10 then respectively transforms into a rotational and pivoting motion and said squeegee continuously screen-prints one of the two respective bus bars onto the 3D plastic window 1 such that it overlaps the grid lines of the applied grid line pattern. Subsequently, the two bus bars and the grid lines overlapping these bus bars are at the respective overlapping points electrically connected into the electric heat conductor structure by means of electrical connectors.

(15) If two displaceable squeegees 10 that operate in two different directions are used instead of the one displaceable squeegee 10 capable of printing in opposite directions, the leftward feed motion of the second squeegee 10 on the grid lines of the grid line pattern transforms during the second, oppositely directed step into the rotational and pivoting motion offset in time referred to the first squeegee 10 in order to end at the upper left edge of the 3D plastic window. The transformations from the feed motion of the at least one squeegee 10 to the rotational and pivoting motion or vice versa may respectively take place in a program-controlled fashion.

(16) The two bus bars and the grid lines of the grid line pattern are then joined at the overlapping points by means of a conductive adhesive or by means of soldering.

(17) After the respective application of the grid lines of the grid line pattern and/or one of the two bus bars, it is ensured that the electrically conductive paste printed onto the 3D plastic window 1 can become touch-dry, preferably by means of self-drying, or is thermally cured by means of IR-radiation or UV-radiation or by means of heat transmission.

(18) FIG. 5 shows the squeegee progression of another embodiment of the method according to the invention, in which two different silver pastes are used for the bus bars and for the grid lines of the grid line pattern of the heat conductor structure to be produced. In this two-paste printing process, the bus bars are in step C simultaneously printed on the right and the left side of the 3D plastic window 1 with a first electrically conductive silver paste due to a combined feed motion and rotational motion (sections 1; 2). The grid lines of the grid line pattern are then in step D printed onto the 3D plastic window 1 offset in time with a second silver paste, which has a higher electrical resistance, such that they overlap the bus bars by means of only a feed motion (sections 1-4).

(19) It is important that the respective silver paste printed onto the 3D plastic window 1 is dried after each printing process such that the print pattern cannot smear or stick together. A short holding time of the respective printing process suffices for this purpose. However, the respective silver paste freshly printed onto the 3D plastic window may also be cured by means of heat transmission. UV-curable or IR-curable paste systems may be used as an alternative to thermal curing in order to promote a serial sequence of the printing process.

(20) FIG. 6 shows a block diagram of steps a-g of another embodiment of the method according to the invention, in which the electric heat conductor structure is produced on a 3D plastic window 1 with a combination of the fast and robust screen-printing technique for the bus bars and the very flexible dispensing technology for the grid lines of the grid line pattern. In this case, the feed device 2 feeds the cleaned 3D plastic windows 1 being supplied to at least one screen-printing machine 3, by means of which the bus bars of the electric heat conductor structure to be produced are screen-printed onto the 3D plastic windows 1 with screen-printing ink in the form of a silver paste. The 3D plastic windows 1 with the bus bars screen-printed thereon are then removed from the screen-printing machine 3 by means of a robot or conveyor system 11 and inserted into a dispensing unit 12 that respectively applies the grid lines of the grid line pattern onto the 3D plastic windows 1 by means of dispensing such that they overlap the bus bars and the electric heat conductor structure is produced. On the outlet side of the dispensing unit 12, the 3D plastic windows are removed by means of a removal device 3 and fed to a drying furnace 5 in order to cure the electric heat conductor structure printed thereon. After the latter has dried, the 3D plastic windows 1 are placed into the depositing station 6 arranged downstream of the drying furnace 5.

(21) FIG. 7 shows a schematic block diagram of a space-intensive embodiment of the system according to the invention, for carrying out the method according to FIG. 6. Analogous to FIG. 2, the entire machine arrangement is in this case also realized in the form of two parallel processing lines with opposite transport directions. The space requirement of this embodiment of the system amounts to approximately 20 mapproximately 6 m.

(22) In this embodiment, the feed device 2 for the 3D plastic windows 1 and the screen-printing machine 3 arranged downstream thereof are positioned in the first processing line and the conveyor or robot unit 4, by means of which the 3D plastic windows 1 with the bus bars printed thereon are removed from the screen-printing machine 3 and inserted into the dispensing unit 12, is positioned between the outlet of the screen-printing machine and the inlet of the downstream dispensing unit 12. The robot system 4, by means of which the 3D plastic windows 1 provided with the electric heat conductor structure are removed from the dispensing unit 12 and placed into the drying furnace 5 in order to be cured, is positioned between the outlet of the dispensing unit 12 and the inlet of the drying furnace 5 arranged in the second processing line. In this case, the drying zone of the drying furnace 5 extends in the second processing line opposite to the transport direction of the first processing line, namely over a total length of 9 m. The depositing station 6, into which the 3D plastic windows 1 with the cured electric heat conductor system are placed, is arranged downstream of the outlet of the drying furnace 5.

(23) FIG. 8 shows a space-saving embodiment of the system for carrying out the method according to FIG. 6, in which the space requirement of the system amounts to approximately 15 mapproximately 10 m. In this case, only the feed unit 2 and the at least one screen-printing machine 3 arranged downstream thereof are provided in the first processing line. The dispensing unit 12, the conveyor or robot system 11 arranged downstream thereof and a downstream paternoster furnace instead of drying furnace 5 in FIG. 7, as well as the depositing station 6 for depositing the finished 3D plastic windows 1 arranged on the outlet side of the paternoster furnace, are positioned in the second processing line, the transport direction of which extends opposite to the transport direction of the first processing line. In addition, the robot system with at least one robot for transporting the 3D plastic windows 1 with the bus bars printed thereon by means of the screen-printing machine 3 to the dispensing unit 12 is positioned between the outlet of the screen-printing machine 3 and the inlet of the dispensing unit 12.

(24) It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

(25) Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases in one embodiment or in an embodiment in various places throughout this specification are not necessarily all referring to the same embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

(26) As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

(27) Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

(28) While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

(29) The verbs to comprise and to include are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of a or an, that is, a singular form, throughout this document does not exclude a plurality.

LIST OF REFERENCE NUMBERS

(30) 1 3D plastic window 2 Feed device 3 Screen-printing machine 4 Removal device 5 Drying furnace, paternoster furnace 6 Depositing station 7 First section of drying zone of drying furnace 8 Second section of drying zone of drying furnace 9 Outlet of drying furnace 10 Squeegee 11 Robot or conveyor system 12 Dispensing unit