Method of transferring particles to a substrate

A method of transferring particles onto a moving substrate, the method comprising:

• providing a moving transfer tool that travels along an endless tool path and that comprises a major outer surface layer comprising a multiplicity of through-holes in a pre-determined pattern,
• providing a particle source surface comprising loose particles thereon, wherein the particle source surface is positioned below the transfer tool and proximate a first portion of the tool path so that in the first portion of the tool path there is a gap between the major outer surface layer of the transfer tool and the loose particles on the particle source surface, the gap being at least 0.2 mm at the point of closest approach between the major outer surface of the transfer tool and the loose particles on the particle source surface;
• wherein the through-holes are shaped and sized and the particles are shaped and sized so that each particle does not fully occlude a through-hole into which it is deposited;
• moving the transfer tool along the tool path so that as a section of the transfer tool traverses the first portion of the tool path, a vacuum applied to the section of the transfer tool in the first portion of the tool path causes at least some particles of the loose particles to traverse, generally vertically upward against the pull of gravity, the gap between the particle source surface and the major outer surface layer of the transfer tool and causes individual particles to be deposited singly upon through-holes of the multiplicity of through-holes of the transfer tool;
• and,
• moving the transfer tool further along the tool path so that as the section of the transfer tool bearing particles upon the through-holes thereof enters a second portion of the tool path, the particles are each dislodged from each through-hole and are transferred onto a particle-adherent surface of a moving substrate that is in proximity with the moving transfer tool in the second portion of the tool path,
• wherein the particles are transferred onto the moving substrate in a pre-determined pattern established by the pre-determined pattern of the multiplicity of through-holes in the major outer surface layer of the transfer tool.

A method of transferring particles onto a moving substrate, the method comprising:

• providing a moving transfer tool that travels along an endless tool path and that comprises a major outer surface layer comprising a multiplicity of through-holes in a pre-determined pattern, wherein the moving transfer tool is an endless belt;
• providing a particle source surface comprising loose particles thereon, wherein the particle source surface is positioned below the transfer tool and proximate a first portion of the tool path so that in the first portion of the tool path there is a gap between the major outer surface layer of the transfer tool and the loose particles on the particle source surface, the gap being at least 0.2 mm at the point of closest approach between the major outer surface of the transfer tool and the loose particles on the particle source surface;
• moving the transfer tool along the tool path so that as a section of the transfer tool traverses the first portion of the tool path, a vacuum applied to the section of the transfer tool in the first portion of the tool path causes at least some particles of the loose particles to traverse, generally vertically upward against the pull of gravity, the gap between the particle source surface and the major outer surface layer of the transfer tool and causes individual particles to be deposited singly upon through-holes of the multiplicity of through-holes of the transfer tool;
• and,
• moving the transfer tool further along the tool path so that as the section of the transfer tool bearing particles upon the through-holes thereof enters a second portion of the tool path, the particles are each dislodged from each through-hole and are transferred onto a particle-adherent surface of a moving substrate that is in proximity with the moving transfer tool in the second portion of the tool path,
• wherein the particles are transferred onto the moving substrate in a pre-determined pattern established by the pre-determined pattern of the multiplicity of through-holes in the major outer surface layer of the transfer tool.