Method and apparatus for coating selected regions of a substrate with a film

Patent metadata

Field	Value
Publication number	US-10780689-B2
Application number	US-201916410390-A
Country	US
Kind code	B2
Filing date	May 13, 2019
Priority date	May 27, 2015
Publication date	Sep 22, 2020
Grant date	Sep 22, 2020

Abstract

Method and apparatus for coating selected regions of a surface of a substrate with a film are disclosed. A cyclically moveable transfer member has an imaging surface which is coated with individual particles formed of, or coated with a thermoplastic polymer, and substantially all particles that are not in direct contact with the imaging surface are removed so as to leave a uniform monolayer particle coating on the imaging surface. Selected regions of the imaging surface are exposed to radiation to render the particles tacky within the regions, and the coated imaging surface and the substrate are pressed against one another to cause transfer of only the particles rendered tacky in the coating, such that the transferred particles form a film on the substrate. The monolayer on the imaging surface of the transfer member is replenished with fresh thermoplastic particles and the cycle repeats.

First claim

The invention claimed is:

1. A method of printing a film onto selected regions of a surface of a substrate, which method comprises the steps of:
a) providing a cyclically moveable transfer member having an imaging surface;
b) providing a supply of individual particles formed of, or coated with, a thermoplastic polymer;
c) coating the imaging surface of the transfer member with particles from the supply;
d) removing particles that are not in direct contact with the imaging surface, so as to leave a uniform monolayer particle coating on the imaging surface;
e) exposing selected regions of the coated imaging surface to radiation of sufficient power to render the particles tacky within the selected regions;
f) pressing at least a portion of the coated imaging surface and at least a corresponding portion of the substrate surface against one another, either during or after irradiation, to cause transfer to the surface of the substrate of only the particles that have been rendered tacky; and,
g) removing the particles remaining on the imaging surface after the transfer of the tacky particles to the substrate.

2. A method as claimed in claim 1 , further comprising collecting at least some of the particles removed in step g), and recycling the collected particles for re-application to the imaging surface.

3. A method as claimed in claim 1 , wherein the coating of the imaging surface of step b) is performed by at least one intermediate applicator.

4. A method as claimed in claim 1 , comprising at least one of the further steps of:
(i) heating the imaging surface prior to, or during, step e), and
(ii) cooling the imaging surface subsequent to step f).

5. A printing apparatus for printing a film comprising a thermoplastic material onto selected regions of a surface of a substrate, the apparatus comprising:
a) a moveable endless transfer member having an imaging surface;
b) a coating station at which individual particles made of, or coated with, a thermoplastic polymer are applied to the imaging surface and at which particles not in direct contact with the imaging surface are removed therefrom, such that a uniform monolayer particle coating is formed on the imaging surface;
c) an imaging station at which selected regions of the coated imaging surface are exposed to radiation of sufficient power to render the particles tacky within the selected regions, the imaging station comprising an imaging device for projecting individually controllable laser beams onto the imaging surface as the imaging surface moves in a reference X-direction relative to the imaging station, the imaging device having a plurality of semiconductor chips each having a plurality of laser beam emitting elements mounted on a support;
wherein the individually controllable laser beam emitting elements of each semiconductor chips are arranged in a two dimensional main array of M rows and N columns, the elements in each row having a uniform spacing A r and the elements in each column having a uniform spacing a c , wherein the chips are mounted on a support in such a manner that, when nominally placed, each pair of chips that are adjacent one another in a reference Y-direction, transverse to the X-direction, are offset from one another in the X-direction, such that were all laser beams emitting elements to be activated continuously, and were the imaging surface in motion relative to the imaging station, the emitted laser beams would trace across the imaging surface a set of parallel lines that extend in the X-direction and are substantially uniformly spaced in the Y-direction; and the laser beams of each chip tracing a set of M·N lines that do not overlap the set of lines of the other chip; and,
d) an impression station at which at least a portion of the coated imaging surface and at least a corresponding portion of the surface of the substrate are pressed against one another, either during or after irradiation, to cause transfer to the surface of the substrate of a tacky film formed on the selected regions of the imaging surface by exposure of the monolayer particle coating to radiation,
wherein, during operation, after at least a portion of the transfer member has passed through the imaging and impression stations, the at least a portion of the transfer member which passed through the impression station is returned to the coating station wherein the particle coating on the imaging surface is replenished to a uniform monolayer.

6. A printing apparatus as claimed in claim 5 , wherein the coating station comprises at least one intermediate applicator able to apply the particles to the imaging surface.

7. A printing apparatus as claimed in claim 6 , wherein at least one of the at least one intermediate applicator includes a brush able to brush off at least part of the particles that are not in direct contact with the imaging surface.

8. A printing apparatus as claimed in claim 5 , further comprising a particle supply for supplying the individual particles to the coating station.

9. A printing apparatus as claimed in claim 5 , wherein the coating station comprises at least one of: at least one intermediate applicator and at least one spray head which is able to both apply the particles that are to be applied to the imaging surface and remove at least part of the particles that are not in direct contact with the imaging surface.

10. A printing apparatus as claimed in claim 5 , wherein the imaging surface is hydrophobic and/or charged.

11. A printing apparatus as claimed in claim 5 , wherein the particles are hydrophobic and/or charged.

12. A printing apparatus as claimed in claim 5 , wherein the coating station comprises:
i. at least one spray head for directly or indirectly applying to the imaging surface a fluid stream within which the particles are suspended,
ii. a housing surrounding the spray head and defining an interior plenum for confining the fluid stream, the housing having a rim adjacent to the imaging surface that is configured to prevent egress of particles from a sealing gap defined between the rim of the housing and the surface to be coated, and
iii. a suction source connected to the plenum to extract from the plenum the sprayed fluid and particles suspended in the sprayed fluid, the suction source being operative to extract particles that are not in direct contact with the imaging surface, so as to leave only a single particle layer adhering to the imaging surface on exiting the coating station.

13. A printing apparatus as claimed in claim 12 , wherein the fluid is a gas and/or the plenum is maintained at sub-atmospheric pressure.

14. A printing apparatus as claimed in claim 5 , wherein the elements in each row of the main array of each chip lie on a line parallel to the Y-direction and the elements in each column of the main array of each chip lie on a straight line inclined at an angle to the rows.

15. A printing apparatus as claimed in claim 14 , wherein the chips are arranged in pair of rows on the support and corresponding laser emitting elements of all the chips in each of the two rows lie in line with one another in the Y-direction.

16. A printing apparatus as claimed in claim 15 , wherein the alignment of the chips within the two rows of the pair is such that the respective centers of corresponding elements in any group of three adjacent chips in the X and Y-directions lie nominally at the apices of congruent equilateral triangles.

17. A printing apparatus as claimed in claim 16 , wherein a respective lens is provided for each chip to focus the laser beams emitted by all the elements of the associ

Assignees

• Landa Labs 2012 Ltd

Inventors

• Landa Benzion
• Krassilnikov Anton
• Nagler Michael
• Fahima Moshe
• Rubin Ben Haim Nir
• Aknin Ofer
• Yogev Ronen

Classifications

• G03G15/342

  by forming a uniform powder layer and then removing the non-image areas · CPC title

• G03G15/043

  with means for controlling illumination or exposure (G03G15/041 takes precedence) · CPC title

• G03G15/04072

  by laser · CPC title

• C23C16/0209

  by heating · CPC title

• B41J2/455

  using laser arrays {, the laser array being smaller than the medium to be recorded} · CPC title