Information
-
Patent Grant
-
6352330
-
Patent Number
6,352,330
-
Date Filed
Wednesday, March 1, 200024 years ago
-
Date Issued
Tuesday, March 5, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 347 12
- 347 15
- 347 40
- 347 41
- 347 43
- 347 237
- 347 240
- 347 215
- 347 258
- 347 172
- 358 518
- 358 523
-
International Classifications
-
Abstract
An ink jet plate maker and proofer apparatus (66) and method adapted for printing a proof of a work to be printed, and making a printing plate (16) for printing the work, including a first element (68) including circuitry (70) controllably operable for generating ink drops of a first predetermined volume for printing the proof on a proofing receiver, and a second element (86) including circuitry (88) controllably operable for generating liquid drops of a second predetermined volume for image wise making or completing the printing plate (16), the second predetermined volume being different from the first predetermined volume. According to an exemplary embodiment, the apparatus includes a first print head (82) connected in fluid communication with a source of ink (106) for printing the proof of the work, and a second print head (92) in fluid communication with a source of a liquid (108) for making the printing plate, the print heads (82, 92) being disposed for ejecting drops of the ink and the liquid for making the printing plate onto a proofing receiver and a treated plate, respectively, positionable on a platen (96) relatively moveable with respect to the print heads (82, 92). The first element (68) is connected in electrical communication with the first print head (82) and includes a first clock (72) connected to a signal generator (76) operable for producing a drive signal for generating the ink drops of the first predetermined volume for printing the proof on the proofing receiver. The second element (86) includes a second clock (90) connected to the signal generator (76) and operable in conjunction therewith for driving the second print head (92) for generating the liquid drops for making the printing plate (16).
Description
FIELD OF THE INVENTION
The present invention relates to an ink jet printer apparatus and method, and more particularly, to an ink jet printer and method for making a printing plate and a proof of a work such as text and/or an image to be printed by the printing plate.
BACKGROUND OF THE INVENTION
When printing, a printing plate for a work is typically made, and then one or more proofs of the work are printed using the printing plate to allow determining desirability and accuracy of the printed image before a large number of prints are printed. The proofing activity might take several stages: an initial, creative stage in which a computer display might be adequate for proofing; an intermediate stage in which a desktop-type inkjet or thermal printer output might be used; and a final, more critical stage in which an accurate picture of the final plate result, including the micro-structure of the halftone dots to be produced on the plate, is desired. It is toward this last need for an accurate halftone proofer, matched to a corresponding platemaker, that the present invention is directed.
It is known to use an ink jet printer to make printing plates. Reference in this regard, Fromson et al. U.S. Pat. No. 5,750,314 issued May 12, 1998 which discloses a method for selectively imaging a lithographic printing plate using an ink jet printer. In the Fromson et al. method, a substrate is coated with a first material, which is soluble in a first solvent, whereupon a second material, which strongly adheres to the first material and insoluble in the first solvent, is selectively applied by an ink jet printer. The substrate is then developed in the first solvent to establish the image. However, Fromson et al. does not disclose a method or apparatus for producing a proof of a work to be printed, without first requiring making the printing plate.
Therefore, what is required is a method and apparatus for printing a proof of a work to be printed using a printing plate, which does not require first making the printing plate. What are also required are an inkjet printer apparatus and method for making both an accurate proof of a work to be printed and a printing plate for the work.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an ink jet printer and method for printing an accurate proof of a work to be printed using a printing plate without first requiring making the printing plate, and for making the printing plate.
With this object in view, the present invention resides in an ink jet printer adapted for printing a proof of a work to be printed and making or completing a printing plate image wise for printing the work, the printer including a first element including circuitry controllably operable for generating ink drops of a first predetermined volume for printing the proof on a proofing receiver, and a second element including circuitry controllably operable for generating liquid drops of a second predetermined volume for making or completing the printing plate image wise, the second predetermined volume being different from the first predetermined volume.
According to an exemplary embodiment of the present invention, the ink jet printer includes a first print head connected in fluid communication with a source of ink for printing the proof of the work, and a second print head in fluid communication with a source of a liquid for making the printing plate, the print heads being disposed for ejecting drops of the ink and the liquid image wise onto a proofing receiver and a treated plate, respectively, positionable on a platen relatively moveable with respect to the print heads. The first element is connected in electrical communication with the first print head and includes a first clock connected to a signal generator operable for producing a drive signal for driving the print head for generating the ink drops of the first predetermined volume for printing the proof on the proofing receiver. The second element includes a second clock connected to the signal generator and operable in conjunction therewith for driving the second print head for generating the liquid drops for printing the image on the treated plate for making or completing the printing plate. A machine control is connected to the signal generator and is operable for selecting the first print head and the first clock for ejecting the ink drops image wise onto the proofing receiver, which can be a sheet of proofing paper or the like, for creating the proof, or the second print head and the second clock for ejecting the liquid image wise onto the treated plate for making or completing the printing plate.
The treated plate for instance can be a grained, anodized aluminum or polyester plate having a hydrophilic surface and having a known surface treatment to control spreading of ink drops thereon. The liquid deposited on the treated surface for instance can include an oleophilic liquid containing a polymer such as pyridine-containing polymer. Such liquids are preferred as they have a known ability to pick up and deliver printing inks to a blanket roller of a printing press. Such liquids are also known for the durability of the dried spots that are formed.
A feature of the present invention is the provision of an ink jet printer adapted for making or image wise completing a printing plate, and a proof of a work to be printed using the printing plate without first requiring making the printing plate.
Another feature of the invention is the provision of an ink jet printer operable to produce drops having different characteristics for printing corresponding images of a work on different printing receivers.
As an advantage of the present invention, a printing plate and a proof of a work to be printed using the printing plate can be produced using the same apparatus.
As another advantage, an accurate proof of a work to be printed using a printing plate can be produced, thus avoiding cost and time lost producing an undesirable or incorrect printing plate.
According to the invention, the volume characteristics of drops of ink or other liquid produced by an ink jet printer can be varied by altering aspects of the drive signal used for producing the drops, including, but not limited to, the voltage, frequency, and/or wave form of the drive signal.
These and other objects, features an advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there are shown and described illustrative embodiments of the invention.
BRIEF DESCRIPTIONS OF TEE DRAWINGS
While the specification concludes with the claims particularly pointing out and distinctly claiming the subject matter of the present invention, it is believed the invention will be better understood from the following detailed description when taken in conjunction with accompanying drawings wherein:
FIG. 1
a simplified schematic view of an ink jet print head showing ejection of a liquid drop therefrom onto a treated plate;
FIG. 2
is a graphical presentation of dot diameter versus drop volume for printing receivers generally;
FIG. 3
is another graphical representation of dot diameter versus drop volume for a variety of different receiving surfaces;
FIG. 4
is a graphical representation of percent measured dot area versus nominal percent dot area for a conventional printing plate, illustrating dot gain;
FIG. 5
is a graphical representation of dot size versus drop volume for several printing receivers and a selected treated plate;
FIG. 6
a
is a graphical representation of a drop volume versus drive signal frequency, generally;
FIG. 6
b
is another graphical representation of drop volume versus drive signal frequency for a representative piezoelectric ink jet print head;
FIG. 7
a
is a graphical representation of a drive signal wave form according to the present invention;
FIG. 7
b
is a graphical representation of the drive signal wave form of
FIG. 7
a
and a second drive signal wave form according to the invention;
FIG. 7
c
is a graphical representation of other drive signal wave forms according to the invention; and
FIG. 8
schematic representation of an ink jet printer according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
The present description will be directed in particular to elements forming part of, or cooperating more directly with, an apparatus and method in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art.
Therefore, referring to
FIG. 1
, an ink jet print head
10
is shown ejecting a liquid drop
12
onto a surface
14
of a treated plate
16
in an image wise manner for making or completing a printing plate. Plate
16
includes a substrate
18
of a conventional material such as aluminum or polyester, and a layer
20
of a known surface treatment to control spreading of ink and other liquids deposited on surface
14
. Layer
20
can include, but is not limited to, surfactants with hydrophilic heads and hydrophobic tails, and other well known substances. Liquid drops, represented by drop
12
, are delivered to surface
14
in an image wise manner and comprise a liquid, such as a liquid containing a polymer such as, but not limited to, a pyridine-containing polymer, which has an observed ability after drying to pick up and deliver printing inks to a blanket roller of a printing press, and excellent durability even after much use.
As another alternative, layer
20
can include for instance any of the substances identified as the first material for picking up ink, or a primer, as disclosed in Fromson et al. U.S. Pat. No. 5,750,314, discussed hereinabove and incorporated herein by reference, drops
12
being suitably composed of a compatible adhesive or other of the second materials disclosed in the Fromson et al. patent.
According to the present invention, print head
10
, or another print head, can be used to deliver ink drops to a surface of a proofing receiver (not shown) in a similar image wise manner to produce a proof of a work to be printed using plate
16
, the delivered ink drops and liquid drops being of different predetermined volumes so as to form corresponding printed dots on the plate or proofing receiver such that the image of the proof is accurately representative of or replicates the image to be printed using the plate, the different drop volumes being controlled by drive signals received from drive circuitry for the print head or print heads.
Referring to
FIG. 2
, a curve
22
is shown illustrating a known relationship of dot diameter in micrometers (um) to drop volume in picoliters (pL) for typical printed dots, it being observed that dot size increases as drop volume increases.
Referring to
FIG. 3
, curves
24
,
26
,
28
, and
32
illustrate the relationship of dot diameter to jetted drop volume for dots of various liquids delivered by a typical ink jet printer onto plates having layers of a variety of different treatments thereon, namely, curve
32
representing no treatment and curves
24
,
26
,
28
representing varying types of chemical treatments, respectively.
In
FIG. 4
, a curve
34
represents measured percent area coverage as a function of nominal percent area coverage for typical dots on a conventional printing plate, and a curve
36
represents measured percent area coverage as a function of nominal percent area coverage for dots printed on a printing receiver such as press paper using the printing plate, the vertical distance, represented as X, between curves
34
and
36
at any given point representing dot gain, that is, the difference between the percent of area covered by the dot formed on the printing plate, and the percent of area of the dot printed on the paper by the dot on the printing plate. Typically, it has been found that the percent area coverage on the print is 15-18 percent larger than the percent area coverage on the plate, and the printed dot will be 7-10 percent larger than the dot on the plate.
To illustrate the effect of this difference in dot sizes, reference is made to
FIG. 5
wherein curve
38
represents dot size as a function of drop volume for dots formed on a treated plate such as plate
16
in the manner described above with reference to FIG.
1
. Curve
40
represents dot size as a function of drop volume for ink dots printed on paper by the dots of curve
38
, the vertical distance between curves
38
and
40
corresponding to the dot gain. Curve
42
represents dot size as a function of drop volume for dots printed by an ink jet printer on a treated paper, and curve
44
represents dot size as a function of drop volume for dots printed by an ink jet printer on a conventional proofing paper.
As an example, if it were decided to make a printing plate having a dot size of 30 um, as shown at point
46
, using curve
38
, the required drop volume of the liquid used for producing the dots on the printing plate in the manner described in reference to
FIG. 1
would be 12 pL. The resulting size of dots printed by the dots on the treated plate would then be 33 um, as shown at point
48
on curve
40
, due to the dot gain. If the ink jet printer were used to print ink dots on the proofing paper of curve
44
using the same drop volume, the resultant dots would have a size substantially greater than 33 um, as shown at point
50
. However, if the drop volume were reduced to 7 pL, the resultant dots printed on the proofing paper would be the desired 33 um size, as shown at point
52
, such that a proof printed with the 7 pL drops will be accurately representative of a print printed by the dots on the treated plate made using the 12 pL drops. Similarly, a proof printed on treated paper using 9 pL drops would have the desired 33 um size dots, as shown at point
54
on curve
42
. This demonstrates that characteristics or parameters of the paper used for proofing can be varied to facilitate matching dot size with a print made using a printing plate, for instance by minimizing the difference between the liquid drop volume required for making the printing plate and the ink drop volume required for making the matching proof.
It has been found that some ink jet printheads can be made to produce drops of different volumes by varying parameters of the drive signals used for producing the drops. For instance, for some printers it has been found generally that drop volume can be varied as a function of signal frequency, a plot
56
of drop volume verses drive signal frequency, generally, being shown in
FIG. 6
a
, illustrating a decrease in drop volume as drive signal frequency increases. Referring to
FIG. 6
b
, a plot
58
of drop volume verses drive signal frequency for a typical shear-mode piezoelectric ink jet print head is shown, again, drop volume generally decreasing as the drive signal frequency increases.
Turning to
FIG. 7
a
, a trace
58
of a drive signal wave form for a shearmode piezoelectric ink jet print head is shown, the vertical axis representing voltage and the horizontal axis representing time, the wave form frequency and voltage amplitude of the trace being denoted.
FIG. 7
b
shows trace
58
and a second drive signal wave form trace
60
, trace
58
being representative of a drive signal having a frequency of about 120 kHz, and trace
60
being representative of a 60 kHz drive signal of the same amplitude, for driving a shear-mode piezoelectric ink jet printer for producing a 7 pL drop and a 12 pL drop, respectively. Referring back to the discussion with reference to
FIG. 5
, a 12 pL drop of a liquid for forming a printing plate will result in a 33 um printed dot on the press, and a 7 pL drop of ink will form a 33 um printed dot on a piece of proofing paper.
Referring to
FIG. 7
c
, alternative drive signal traces
62
and
64
for a shear-mode piezoelectric ink jet printer are shown, both traces
62
and
64
having a generally sinusoidal wave form shape, trace
62
having a single drive pulse and trace
64
having a two drive pulses, for producing smaller and larger drops, respectively.
Referring to
FIG. 8
, an ink jet proof making and printing plate making apparatus constructed and operable according to the above-discussed teachings of the present invention is shown. Apparatus
66
includes a first element
68
including circuitry
70
controllably operable for generating ink drops of a first predetermined volume for printing the proof on a proofing receiver. Circuitry
70
includes a first clock
72
selectably connectable by a switch
74
in electrical communication with a signal generator
76
for driving signal generator
76
at a first frequency. Signal generator
76
is connected in electrical communication with a machine control
78
and an amplifier
80
, which, in turn, is selectably connectable in electrical communication with a first ink jet print head
82
by a switch
84
. Apparatus
66
includes a second element
86
including circuitry
88
controllably operable for generating liquid drops of a second predetermined volume for making the printing plate, the second predetermined volume being different from the first predetermined volume. Circuitry
88
includes a second clock
90
selectably connectable by switch
74
in electrical communication with signal generator
76
for driving signal generator
76
at a second frequency, signal generator
76
again being connected to machine control
78
and to amplifier
80
, which, in turn, is selectably connectable to a second ink jet print head
92
by switch
84
. Switches
74
and
84
can be jointly switchable, for instance by machine control
78
, as desired, to allow selecting the first or second frequency and associated print head
82
,
92
.
Print heads
82
and
92
are threadedly mounted for longitudinal movement on a rotatable cross screw
94
in spaced, opposed relation to a platen
96
. Platen
96
, in turn is threadedly mounted for longitudinal movement on a lead screw
98
oriented at a right angle to cross screw
94
. Cross screw
94
is rotatable by a drive motor
100
, and lead screw
98
is rotatable by a similar drive motor (not shown) while print heads
82
,
92
are prevented from rotating, for relatively moving print heads
82
,
92
and platen
96
longitudinally along the screws in the well known conventional manner for positioning the print heads
82
,
92
in desired relation to a top surface
102
of the platen. Top surface
102
is conventionally adapted for receiving a printing plate such as treated plate
16
and/or a proofing receiver, such as a piece of paper, as represented by element
104
, and holding the plate or receiver using vacuum or the like, for receiving ink or liquid drops in an image wise manner during the relative movement. Print head
82
is connected in fluid communication with an ink source
106
such as a tank or reservoir containing inks, which may include one to six or more different ink colors, and print head
92
is connected in fluid communication with a source of liquid
108
for making a printing plate such as plate
16
, by flexible lines
110
and
112
, respectively, to provide ink or liquid delivery to the print heads
82
,
92
during the relative movement.
Signal generator
76
is adaptable for generating drive signals having any of the wave form shapes shown in
FIGS. 7
a
,
7
b
and
7
c
, at a frequency determined by the clock
72
or
90
selectably connectable thereto. For example, for printing proofs on a printing receiver, the frequency of first clock
72
can be set to produce the above discussed 120 kHz for driving print head
82
for producing ink drops having a volume of 7 pL, and the frequency for second clock
90
can be set to produce the above discussed 60 kHz for driving print head
92
for producing 12 pL liquid drops for making the printing plate. Again referring to
FIG. 5
, a resultant proof printed using ink drops of 7 pL volume will have image wise dots of a 33 um size, and prints printed by the printing plate made using 12 pL liquid drops will also have 33 um dots, such that the proof will accurately reproduce or replicate the image to be printed using the printing plate.
It may be appreciated from the description hereinabove, that according to the present invention, a proof accurately representative of or replicating a work to be printed using a printing plate can be produced by an ink jet printer. As taught above, this is achieved by utilizing a drive signal for the ink jet printer operable for emitting ink drops of a volume for producing printed dots on a selected proofing receiver of a size equal or substantially equal to the dot size of the work when printed using the printing plate. The required drop volume can be achieved by adjusting the frequency of the drive signal, the wave form thereof, the amplitude thereof, or any other characteristic which suitably effects drop volume.
It may also be appreciated that the ink jet printer can utilize a wide variety of conventional print head constructions, including, but not limited to, a shear-mode piezoelectric print head. The printer platen may be flat, or it may be in the form of a moving cylinder. The print head drive waveforms may be varied by changing the signal generator frequency, or by retrieving any one of a number of digital waveforms, stored in memory. The printer may also include a single print head for making the printing plate and printing the proof, or different print heads for those functions. The treated plate, for instance, can be an aluminum or polyester plate having a surface treatment to control spreading of ink drops thereon. The liquid deposited on the treated surface, for instance, can include but is not limited to a liquid containing a polymer such as pyridine-containing polymers.
It may be further appreciated that as an advantage of the present invention, a printing plate and a proof of a work to be printed using the printing plate can be produced using the same apparatus.
As another advantage, an accurate proof of a work to be printing using a printing plate can be produced, thus avoiding cost and time lost producing an undesirable or incorrect printing plate.
While the invention has been described with particular reference to its preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements of the preferred embodiment without departing from the invention. In addition, many modifications may be made to adapt a particular situation and material to a teaching of the present invention without departing from the essential teachings of the invention.
Therefore, what is provided is an ink jet printer and method for printing an accurate proof of a work to be printed using a printing plate without first requiring making the printing plate, and for making the printing plate.
Parts List
10
ink jet print head
12
fluid droplet
14
surface
16
treated plate
18
substrate
20
layer
22
graph
24
curve
26
curve
28
curve
32
curve
34
curve
36
curve
38
curve
40
curve
42
curve
44
curve
46
point
48
point
50
point
52
point
54
point
56
representative plot
58
representative plot
60
trace
62
trace
64
trace
66
apparatus
68
first element
70
circuitry
72
first clock
74
switch
76
signal generator
78
machine control
80
amplifier
82
first ink jet print head
84
switch
86
second element
88
circuitry
90
second clock
92
second ink jet print head
94
cross screw
96
platen
98
lead screw
100
drive motor
102
top surface
104
representative element
106
ink source
108
source of liquid
110
line
112
line
Claims
- 1. An ink jet printer for printing a proof of a work to be printed and making a printing plate for printing the work comprising;a first element including circuitry controllably operable for generating ink drops of a first predetermined volume for printing the proof on a proofing receiver, the proof having micro-structures of dots that for halftone dots; and a second element including circuitry controllably operable for generating liquid drops of a second predetermined volume for making the printing plate, the second predetermined volume being different from the first predetermined volume, wherein micro-structure of dots that form halftone dots on the plate are matched to that on the proof so that a print from the plate can be printed that has halftone dot micro-structures that are substantially identical to that of the proof.
- 2. The ink jet printer of claim 1, wherein the first and second elements each comprise a piezoelectric print head.
- 3. The ink jet printer of claim 2, further comprising a platen adapted for holding the printing plate and the proofing receiver and apparatus for relatively moving the platen and the piezoelectric print heads.
- 4. The ink jet printer of claim 2, wherein the circuitry of the first element includes a first clock operable at a first speed, the circuitry of the second element includes a second clock operable at a second speed different from the first speed, and the printer includes a signal generator connectable in driven relation to the first and second clocks, respectively, and in driving relation to the print heads, respectively.
- 5. The ink jet printer of claim 1, wherein the circuitry includes a signal generator operable for controlling the volume of the generated drops by controlling a voltage parameter of a drive signal generated thereby.
- 6. The ink jet printer of claim 1, wherein the circuitry includes a signal generator operable for controlling the volume of the generated drops by controlling a wave form parameter of a drive signal generated thereby.
- 7. A method for printing a proof of a work to be printed and making a printing plate for the work, comprising the steps of:a. providing an ink jet printer including circuitry and a print head controllably operable for generating ink drops of a first predetermined volume for printing the proof of the work on a proofing receiver, and circuitry and a print head controllably operable for generating drops of a second predetermined volume of a liquid for making the printing plate, the second predetermined volume being different from the first predetermined volume; b. controllably operating the first named circuitry and print head for printing the proof on a printing receiver; the proof being formed with micro-structures of dots that form halftone dots; and c. controllably operating the second named circuitry and print head for making the printing plate, the plate being formed with micro-structures of dots that form halftone dots which are matched to that on the proof so that a print from the plate can be printed that has halftone dot micro-structures substantially identical to that of the proof.
- 8. The method of claim 7, wherein the first named circuitry and print head is controllably operated at a first drive signal frequency.
- 9. The method of claim 8, wherein the first named circuitry comprises a clock operable at the first drive signal frequency.
- 10. The method of claim 7, wherein the second named circuitry and print head is controllably operated at a second drive signal frequency.
- 11. The method of claim 10, wherein the second named circuitry comprises a clock operable at the second drive signal frequency.
- 12. The method of claim 7, wherein the first named circuitry and print head is operated for generating said ink drops of the first predetermined volume using a first drive signal wave form and the second named circuitry and print head is operated for generating said ink drops of said second predetermined volume using a second drive signal wave form different from said first drive signal wave form.
- 13. The method of claim 12 wherein the first drive signal wave form is different from the second drive signal wave form in amplitude.
- 14. The method of claim 12 wherein the first drive signal wave form is different from the second drive signal wave form in frequency.
- 15. An ink jet printer adapted for making printing plates and proofs of works to be printed using the printing plates, comprising:a first element including circuitry operable for generating ink drops of a first controlled volume for making the proofs, each proof having micro-structures of dots that form halftone dots; a second element including circuitry operable for generating drops of a second controlled volume of a liquid for making t he printing plates, each plate corresponding to a proof having micro-structures of dots that form halftone dots on the plate that are matched to that on the proof so that a print from the plate can be printed that has a halftone dot micro-structure that is substantially identical to that of the proof; and a control element for selectively operating the first element or the second element for generating the drops of a selected controlled volume.
- 16. The ink jet printer of claim 15, wherein said first element further comprises a print head and a source of ink connected to said print head.
- 17. The ink jet printer of claim 15, wherein said second element further comprises a print head and a source of said liquid connected to said print head.
- 18. The ink jet printer of claim 17, wherein said liquid comprises a polymer containing liquid.
- 19. A method for producing an image formed of printed dots on a final receiver sheet printed using a printing plate, the method comprising:operating an inkjet printer including a printhead and driver circuitry for operating the printhead to generate ink drops of a first ink drop volume on a proofing receiver to form an image substantially identical to that to be formed on the final receiver sheet; determining a second ink drop volume for printing dots using inkjet printing on a printing plate based an observation of dot size in the proofing receiver and dot said between dots printed on the printing plate and dots formed on a final receiver sheet that comprises a print to be made using the printing plate; printing by inkjet printing an image on the printing plate using the second ink drop volume determined, the image on the printing plate having a dot size suited for printing the image to be formed on the final receiver sheet and the second ink drop volume being different than the volume of the first ink drop volume; and printing the image on the final receiver sheet to form the print using the printing plate, the dot size printed on the final receiver sheet being substantially identical to that formed on the proofing receiver.
- 20. The method according to claim 19 wherein in the step of determining the dot size of dots in the proofing receiver the micro-structures of halftone dots in the proofing receiver are examined.
- 21. The method according to claim 20 wherein the second ink drop volume is larger than the first ink drop volume.
- 22. The method according to claim 19 wherein the second ink drop volume is larger than the first ink drop volume.
US Referenced Citations (35)
Foreign Referenced Citations (1)
Number |
Date |
Country |
0 776 763 |
Nov 1996 |
EP |