Self-registering fluid droplet transfer methods

Details Self-registering fluid droplet transfer methods Self-registering fluid droplet transfer methods

2002-08-05

2003-11-18

Gordon, Raquel Yvette (Department: 2853)

Incremental printing of symbolic information

Ink jet

Medium and processing means

Reexamination Certificate

active

06648468

ABSTRACT:

TECHNICAL FIELD
The invention pertains to the general field of printing and in particular to inkjet printing.
BACKGROUND
While there is a considerable variation in the products on offer and the specific technology employed, inkjet printing typically involves expelling small droplets of ink-bearing liquid from miniature nozzles onto the surface of a substrate. Each droplet represents a pixel to be printed. An array of such nozzles is then scanned across (i.e. moved relative to) the substrate in order to address each pixel position. An electronic control unit controls the scanning process and, depending on the image data, sends instructions to individual nozzles as to whether they should print at a given position or time. Because the electronic control unit directs nozzles to expel ink droplets or to refrain from expelling ink droplets based on image data, the ink droplets are said to be “image-wise” expelled onto the substrate. Some color printers use inkjet technology.
FIG. 1
depicts a prior art inkjet head
10
printing on a substrate
12
. Inkjet head
10
comprises an array
16
of inkjet nozzles
14
. For the sake of clarity, inkjet head
10
is depicted in
FIG. 1
as comprising a single one-dimensional array
16
of nozzles
14
. The image-wise expulsion of ink from each individual nozzle
14
is controlled by a controller (not shown). The controller moves inkjet head
10
in a scan direction
18
relative to substrate
12
and, using image data, directs individual nozzles
14
to eject fluid ink droplets
20
. Repeated emission of fluid ink droplets
20
creates tracks or channels
22
of image-wise printed dots
24
on the surface of substrate
12
. Ideally, as exemplified by nozzle
14
A, fluid ink droplets
20
A are ejected substantially straight from the tips of nozzle
14
to form substantially straight channels
22
on substrate
12
.
A problem with inkjet printing is illustrated by nozzle
14
E. As shown in
FIG. 1
, the fluid ink droplets
20
E emitted by nozzle
14
E exhibit inconsistent trajectories resulting in image-wise printed dots
24
E that are not properly aligned in their channel
22
E. Inconsistent or off-center expulsion of fluid ink droplets
20
by nozzles
14
may result in printed images that exhibit banding or striations. Inconsistent or off-center expulsion may be may be caused, inter alia, by partially failed or clogged nozzles
14
, by aerodynamic forces that change the paths of fluid ink droplets
20
, and by “cross-talk effects” between adjacent or closely proximate nozzles
14
.
In effort to reduce the inconsistency of fluid droplet emission trajectories, U.S. Pat. No. 4,054,882 (Ruscitto), U.S. Pat. No. 4,219,822 (Paranjpe) and U.S. Pat. No. 4,525,721 (Crean) disclose the use of electrostatic fields to guide fluid ink droplets after they have been emitted from inkjet nozzles.
PCT Application No. PCT/IL96/00150 and U.S. Pat. No. 6,354,701 (the “Korem Patents”) disclose apparatus for ink jet printing involving a printing member patterned with an ink receptive portion having a number of ink receptive dots in a desired resolution and an ink repelling portion that includes the remaining area of the printing member. Fluid ink droplets are image-wise expelled from nozzles onto the ink receptive dots and then transferred from the printing member to a printing substrate.
Intermediate transfer surfaces, such as the printing member of the Korem Patents, have a tendency to retain ink, thereby decreasing ink utilization efficiency, reducing the amount of ink transferred to the substrate and making the intermediate transfer surfaces difficult to clean.
There is a need for inkjet printing apparatus and methods that ameliorate at least some of the disadvantages mentioned above.
SUMMARY OF THE INVENTION
In accordance with the present invention, a method for the image-wise transfer of fluid droplets from at least one fluid droplet source onto a substrate is disclosed. The fluid droplets may be water-based or oil-based. If the fluid droplets are water-based, the method comprises ejecting the fluid droplets from fluid droplet source onto a hydrophobic transfer surface which comprises a spatially periodic plurality hydrophobic regions that are less hydrophobic than a remainder of the transfer surface. If the fluid droplets are oil-based, the method comprises ejecting the fluid droplets from fluid droplet source onto a oleophobic transfer surface which comprises a spatially periodic plurality oleophobic regions that are less oleophobic than a remainder of the transfer surface. The method also comprises transferring the fluid droplets from the transfer surface to the substrate by bringing the fluid droplets on the transfer surface into contact with the substrate.
The method may also involve adjusting a spatial registration of the fluid droplets on the transfer surface, wherein adjusting the spatial registration of the fluid droplets on the transfer surface may comprise permitting the fluid droplets to interact with the hydrophobic (oleophobic) transfer surface and at least one of the plurality of less hydrophobic (oleophobic) regions.
The fluid droplet source may comprise a plurality of fluid droplet sources spaced apart from one another by a separation and there may be an integer relationship between a period of the less hydrophobic (oleophobic) regions and the separation of the fluid droplet sources.
The method may involve modifying one or more rheological characteristics of the fluid droplets while the fluid droplets are on the transfer surface. Such modifications may involve: curing the fluid droplets, partially curing the fluid droplets, increasing a viscosity of the fluid droplets, changing a solubility of the fluid droplets, changing a surface energy of the fluid droplets and/or evaporating a solvent contained in the fluid droplets. Such modifications may be accomplished by: irradiating the fluid droplets with electromagnetic energy; subjecting the fluid droplets to vacuum treatment, subjecting the fluid droplets to gaseous flow treatment, subjecting the fluid droplets to chemical treatment and heating the fluid droplets.
The method may comprise modifying sizes of the fluid droplets while the fluid droplets are on the transfer surface.
The fluid droplet source may comprise an ink jet printer head. The transfer surface may be disposed on a cylindrical surface of a drum roller or, alternatively, may be the surface of a drum roller. Bringing the fluid droplets on the transfer surface into contact with the substrate may comprise rolling the substrate against the drum roller.
The transfer surface may comprise a belt member and the method may involve circulating the belt member while ejecting fluid droplets onto the transfer surface.
The less hydrophobic (oleophobic) regions may be periodic in one dimension. They may also be periodic in two dimensions. The less hydrophobic (oleophobic) regions may comprise depressions in the hydrophobic (oleophobic) transfer surface.
Ejecting fluid droplets from the one or more fluid sources onto a hydrophobic (olephobic) transfer surface may comprise making multiple passes between the inkjet head and the transfer surface and, in each such pass, depositing a plurality of fluid droplets onto the transfer surface. The plurality of fluid droplets deposited on each pass may comprise fluid droplets of a different color. The pluralities of fluid droplets deposited during successive passes may be spatially interleaved with one another.
Transferring the fluid droplets from the transfer surface to the substrate may comprise making multiple passes between the transfer surface and the substrate and, in each such pass, transferring a plurality of fluid droplets onto the substrate. The plurality of fluid droplets transferred on each pass may comprise fluid droplets of a different color. The pluralities of fluid droplets deposited during successive passes may be spatially interleaved with one another.
The method may comprise curing the fluid droplets on the substrate, which may involve: irradiating the fluid droplets with electromagnetic

Affiliated with

Also associated with

Rating

Self-registering fluid droplet transfer methods does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Self-registering fluid droplet transfer methods, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Self-registering fluid droplet transfer methods will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3178301