Information
-
Patent Grant
-
6508552
-
Patent Number
6,508,552
-
Date Filed
Friday, October 26, 200122 years ago
-
Date Issued
Tuesday, January 21, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 347 102
- 347 101
- 347 104
- 347 105
- 347 106
- 347 107
- 347 43
- 347 4
- 399 320
- 346 25
- 219 216
- 101 488
- 034 304
- 034 381
- 516 70
- 008 471
-
International Classifications
-
Abstract
A printer having precision ink drying capability and method of assembling the printer. The printer comprises a print head that is adapted to eject a plurality of ink drops through outlet orifices defined by the print head. The ink drops form a plurality of ink marks at a plurality of locations on a recording medium positioned opposite the outlet orifices. A plurality of heaters is disposed near the print head for heating the ink marks on the recording media in order to dry the ink marks. Drying the ink marks fixes the ink to the recording media. A plurality of sensors, that are disposed near the print head are also coupled to respective ones of the heaters for sensing the locations of the ink marks on the recording media. In addition, a controller interconnects each of the heaters to respective ones of the sensors for selectively energizing the heaters according to the locations of the ink marks sensed on the recording media by the sensors. Thus, the controller selectively informs the heaters of the locations of the ink marks on the recording media as the sensors sense the ink marks. In this manner, the heaters dry only the locations having ink marks with optimized energy output.
Description
BACKGROUND OF THE INVENTION
The present invention generally relates to printer apparatus and methods and more particularly relates to a printer having precision ink drying capability and method of assembling the printer.
An ink jet printer produces images on a recording medium by ejecting ink droplets onto the recording medium in an image-wise fashion. The advantages of non-impact, low-noise, low energy use, and low cost operation in addition to the ability of the printer to print on plain paper are largely responsible for the wide acceptance of ink jet printers in the marketplace.
Ink jet printers comprise a print head that includes a plurality of ink ejection orifices. At every orifice a pressurization actuator is used to produce an ink droplet. In this regard, either one of two types of actuators may be used. These two types of actuators are heat actuators and piezoelectric actuators. With respect to piezoelectric actuators, a piezoelectric material is used. The piezoelectric material possesses piezoelectric properties such that an electric field is produced when a mechanical stress is applied. The converse also holds true, that is, an applied electric field will produce a mechanical stress in the material. Some naturally occurring materials possessing this characteristic are quartz and tourmaline. The most commonly produced piezoelectric ceramics are lead zirconate titanate, lead metaniobate, lead titanate, and barium titanate. When a piezoelectric actuator is used for inkjet printing, an electric pulse is applied to the piezoelectric material causing the piezoelectric material to bend, thereby squeezing an ink droplet from an ink body in contact with the piezoelectric material. The ink droplet thereafter travels toward and lands on the recording medium. One such piezoelectric inkjet printer is disclosed by U.S. Pat. No. 3,946,398 titled “Method And Apparatus For Recording With Writing Fluids And Drop Projection Means Therefor” issued Mar. 23, 1976 in the name of Edmond L. Kyser, et al.
With respect to heat actuators, such as found in thermal ink jet printers, a heater placed at a convenient location heats the ink and a quantity of the ink phase changes into a gaseous steam bubble. The steam bubble raises the internal ink pressure sufficiently for an ink droplet to be expelled towards the recording medium. Thermal inkjet printers are well-known and are discussed, for example, in U.S. Pat. No. 4,500,895 to Buck, et al.; U.S. Pat. No. 4,794,409 to Cowger, et al.; U.S. Pat. No. 4,771,295 to Baker, et al.; U.S. Pat. No. 5,278,584 to Keefe, et al.; and the Hewlett-Packard Journal, Vol. 39, No. 4 (August 1988), the disclosures of which are all hereby incorporated by reference.
The print head itself may be a carriage mounted print head that reciprocates transversely with respect to the recording medium (i.e., across the width of the recording medium) as a controller connected to the print head selectively fires individual ones of the ink ejection chambers, in order to print a swath of information on the recording medium. After printing the swath of information, the printer advances the recording medium the width of the swath and the print head prints another swath of information in the manner mentioned immediately hereinabove. This process is repeated until the desired image is printed on the recording medium. Alternatively, the print head may be a pagewidth print head that is stationary and that has a length sufficient to print across the width of the recording medium. In this case, the recording medium is moved continually and normal to the stationary print head during the printing process.
Inks useable with piezoelectric and thermal ink jet printers, whether those printers have carriage-mounted or page-width print heads, are specially formulated to provide suitable images on the recording medium. Such inks typically include a colorant, such as a pigment or dye, and an aqueous liquid, such as water, and/or a low vapor pressure solvent. More specifically, the ink is a liquid composition comprising a solvent or carrier liquid, dyes or pigments, humectants, organic solvents, detergents, thickeners, preservatives and other components. Moreover, the solvent or carrier liquid may be water alone or water mixed with water miscible solvents such as polyhydric alcohols, or organic materials such as polyhydric alcohols. Once applied to the recording medium, the liquid constituent of the ink is removed from the ink and recording medium by evaporation or polymerization in order to fix the colorant to the recording medium. In this regard, the liquid constituent of the ink is removed by natural air drying or by active application of heat. Various liquid ink compositions are disclosed, for example, by U.S. Pat. No. 4,381,946 titled “Ink Composition For Ink-Jet Recording” issued May 3, 1983 in the name of Masafumi Uehara, et al.
As previously mentioned, the colorant is heated in order to fix the colorant to the recording medium. Fixing the colorant to the recording medium avoids offsetting of the liquid colorant onto surfaces coming into contact with the printed recording medium. In this regard, there are three distinct methods for heating the colorant. These methods are convection, radiation and conduction. With respect to convection, a heated gas, such as heated air or nitrogen, is blown onto the colorant on the recording medium. However, use of convective heating is thermally inefficient because air and nitrogen have relatively low heat capacities. Thus, relatively high volumes of the air or nitrogen is necessary to transfer sufficient heat to the colorant. Also, relatively large amounts of heat are required in convective heating systems. That is, the air or nitrogen is usually supplied from an external source where the air or nitrogen is stored at a lower temperature. Thus, a significant amount of heat energy must be supplied to the large volumes of the air or nitrogen in order to raise the temperature of the air or nitrogen sufficiently to dry the colorant. Therefore, a problem in the art is the large volumes of gas and large amounts of energy needed in blower-type colorant drying systems.
Radiation heating transfers heat by electromagnetic waves and occurs when two or more spaced-apart objects are at different temperatures. In the prior art, radiation heating of colorants on recording media is typically accomplished by means of infra-red energy applied to the colorant.
Conductive heating typically requires a heating member that contacts the recording medium to fix the colorant to the recording medium. In this regard, the recording medium may be advanced around a hollow drum having hot oil or high-pressure steam in the hollow portion of the drum. The drum can also be heated electrically by radiation or resistive heaters. The drum conducts heat to the recording medium contacting the drum. However, because the drum must sealingly accommodate the hot oil or high-pressure steam, the drum is complex and costly to manufacture. Also, the drum conducts the same amount of heat along the entire width and length of the recording medium regardless of the varying drying requirements of the recording medium. In other words, the same heat is received by areas of the recording medium not having colorant as well as by areas having colorant thereat. Applying heat to areas of the recording medium not having colorant thereat wastes energy. Also, areas of the recording medium that are heavily wetted by the colorant may not receive sufficient heat energy to dry the colorant. Therefore, another problem in the art is applying the same amount of heat to all locations on the recording medium regardless of whether colorant is present at those locations.
An attempt to address the problems recited hereinabove is disclosed by U.S. Pat. No. 6,256,903 titled “Coating Dryer System” issued Jul. 10, 2001 in the name of Paul D. Rudd. The Rudd device is directed to a drying system in which a substrate is supported about a thermally conductive drum having a plurality of energy emitters disposed circumferentially within the conductive drum at locations along a length of the drum. The plurality of energy emitters are controlled to selectively emit energy along the length of the conductive drum. Moreover, the dryer system preferably includes means for sensing temperatures of the drum along the length of the conductive drum, wherein the energy emitted by the energy emitters along the length of the drum varies based upon the sensed temperatures long the length of the drum. In one preferred embodiment of the Rudd device, the energy emitters comprise annular thin band heaters. Thus, the energy emitters extend along the entire inner circumferential surface of the drum and are positioned side-by-side so as to extend along a substantial portion of the length of the drum. Each annular energy emitter has a diameter comprised for sufficiently encirculating the entire inner diameter of the drum. However, the Rudd patent does not disclose that the energy emitted by the energy emitters varies around the circumference of the drum. Rather, the Rudd patent discloses that the energy emitted by the energy emitters varies merely along the length of the drum. Therefore, the Rudd patent does not appear to disclose control of heat around the circumference of the drum. Thus, in the case of a printed recording medium, a line of printed marks extending the width of the substrate in contact with the drum will receive the same heat input regardless of whether only some locations of the printed line have colorant to be dried. As previously mentioned, applying heat to areas not having colorant thereat wastes energy.
Therefore, what is needed is a printer having precision ink drying capability and method of assembling the printer.
SUMMARY OF THE INVENTION
The present invention resides in a printer having precision ink drying capability, comprising a print head adapted to form an ink mark at a location on a recording media; a dryer associated with the print head for drying the ink mark; and a controller coupled to the dryer for controllably operating the dryer, so that the dryer selectively dries only the ink mark.
According to an aspect of the present invention, a printer having precision ink drying capability comprises a print head that is adapted to eject a plurality of ink drops through outlet orifices defined by the print head. The ink drops form a plurality of ink marks at a plurality of locations on a recording medium positioned opposite the outlet orifices in order to define a printed image on the recording media. A plurality of heaters is disposed near the print head and are distributed transversely across the width of the recording media for heating the ink marks on the recording media in order to dry the ink marks. Drying the ink marks fixes the ink to the recording media. A plurality of sensors, disposed near the print head are distributed transversely across the width of the recording media and are coupled to respective ones of the heaters for sensing the locations of the ink marks on the recording media. In addition, a controller interconnects each of the heaters to respective ones of the sensors for selectively energizing the heaters according to the locations of the ink marks sensed on the recording media by the sensors. Thus, the controller selectively informs the heaters of the locations of the ink marks on the recording media as the sensors sense the ink marks. In this manner, the heaters dry only the locations having ink marks. The heaters may be resistance heaters, microwave heaters or radiant heaters. The sensors may be thermocouples or optical sensors.
A feature of the present invention is the provision of a plurality of sensors adapted to sense presence of ink marks comprising the image printed on the recording media.
Another feature of the present invention is the provision of a plurality of heaters coupled to the sensors for heating only the ink marks sensed by the sensors.
An advantage of the present invention is that use of the present invention saves energy.
Another advantage of the present invention is that amount of heat applied to ink marks varies depending on the amount of ink thereat sensed by the sensors.
Still another advantage of the present invention is that speed of printing is increased.
Yet another advantage of the present invention is that scorching of the recording media is avoided.
A further advantage of the present invention is that use thereof avoids use of the large volumes of gas and large amounts of energy needed to heat the gas, as in blower-type ink drying systems.
These and other features and 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 DESCRIPTION OF THE DRAWINGS
While the specification concludes with 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 description when taken in conjunction with the accompanying drawings wherein:
FIG. 1
is a perspective view of an inkjet printer according to the present invention;
FIG. 2
is perspective view in partial vertical section of the printer;
FIG. 3
is a fragmentary view of the printer, showing internal components belonging to the printer;
FIG. 4
is a view taken along section line
4
—
4
of
FIG. 3
;
FIG. 5
is a fragmentary view of a recording having an image printed thereon comprising a multiplicity of ink marks;
FIG. 6
is a view of a page-width platform having a plurality of heaters and sensors affixed thereto;
FIG. 7
is a graph illustrating an electrical pulse train comprising a plurality of electrical pulses;
FIG. 8
is a fragmentary view of a second embodiment printer of the present invention, showing internal components belonging to the second embodiment printer;
FIG. 9
is a fragmentary view of a third embodiment printer of the present invention, showing a pair of sensors mounted on a reciprocating carriage,
FIG. 10
is a fragmentary view of a fourth embodiment printer of the present invention, showing a single sensor mounted on the reciprocating carriage;
FIG. 11
is a fragmentary view of a fifth embodiment printer of the present invention, wherein the sensors are absent;
FIG. 12
is a flow chart illustrating an algorithm for controlling operation of the heaters and sensors; and
FIG. 13
presents a calibration curve used to control heat input to the ink marks according to ambient relative humidity.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will be directed in particular to elements forming part of, or cooperating more directly with, apparatus 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
FIGS. 1
,
2
,
3
,
4
and
5
there is shown a thermal inkjet printer, generally referred to as
10
, for printing an Image
20
on a recording media
30
. Recording media
30
has top surface
33
and a bottom surface
35
and may be a reflective recording media (e.g., paper or fabric) or a transmissive recording media (e.g., polymer transparency) or other type of recording media suitable for receiving ink that forms image
20
. As described more fully hereinbelow, image
20
is formed by a multiplicity of ink marks
40
. Printer
10
comprises a housing
50
having an inlet opening
60
that receives a supply tray
70
having a stack sheet supply of the recording media therein. Housing also has an outlet opening
80
for egress of a finally printed sheet of recording media
30
. In this regard, the finally printed sheet of recording media
30
will exit printer
10
and will be received by an output tray
90
, so that the printed sheet of recording media
30
can be retrieved by an operator of printer
10
.
Still referring to
FIGS. 1
,
2
,
3
,
4
and
5
, disposed in housing
50
is a picker mechanism, generally referred to as
100
, for picking individual sheets of recording media
30
from supply tray
70
. In this regard, picker mechanism
100
comprises a motor
110
engaging an axle
120
for rotating axle
120
in a direction illustrated by arrow
125
. Affixed to axle
120
is at least one roller
130
adapted to engage a topmost sheet of recording media
30
and transport that sheet of recording media
30
onto a guide ramp
140
, for reasons disclosed presently. Moreover, picker mechanism
100
further comprises a biasing assembly, such as a spring
150
, for biasing roller
130
into engagement with the top-most sheet of recording media
30
when required.
Referring again to
FIGS. 1
,
2
,
3
,
4
and
5
, previously mentioned guide ramp
140
is interposed between supply tray
70
and a print head
160
. In this regard, guide ramp
140
is aligned with print head
160
and supply tray
70
. Print head
160
is preferably a stationary page-width print head comprising a plurality of ink modules
170
a/b/c/d.
Each ink module
170
a/b/c/d
has a plurality of ink ejection chambers
180
therein each holding a predetermined colored ink, such as yellow, magenta, cyan or black ink, respectively. In the preferred embodiment of the present invention, ink is supplied from an external “off-axis” ink supply (not shown). In addition, each ink module
170
a/b/c/d
defines a plurality of ink ejection chambers
180
. Alternatively, each ink module
170
a/b/c/d
may contain its own “on-board” ink supply, if desired. Disposed in each ink ejection chamber
180
is a thin-film thermal resistor
190
for supplying heat to ink in ink ejection chamber
180
. Moreover, in fluid communication with the ink in ink ejection chamber
180
is an outlet orifice
200
for exit of an ink drop
210
from print head
160
, as described in more detail presently. In this regard, each ink ejection chamber
180
is formed opposite its respective outlet orifice
200
so ink can collect between the ink ejection chamber
180
and outlet orifice
200
. Also, each thermal resistor
190
is connected to a controller
220
also disposed in housing
50
. Controller
220
selectively supplies sequential electrical pulses to thermal resistors
190
for actuating thermal resistors
190
. When controller
220
supplies the electrical pulses to thermal resistors
220
, the thermal resistors heats a portion of the ink adjacent to thermal resistors, so that the portion of the ink adjacent thermal resistors
220
vaporizes and forms a vapor bubble (not shown). Formation of the vapor bubble pressurizes the ink in ink ejection chamber
180
, so that ink drop
200
ejects out outlet orifice
200
to produce mark
40
on recording media
30
which is positioned opposite outlet orifice
200
. Image input to controller
220
is by means of an input source
230
connected to controller
220
. Image input source
230
may be a personal computer, scanner, facsimile machine, or the like.
Referring yet again to
FIGS. 1
,
2
,
3
,
4
and
5
, picker mechanism
100
feeds a sheet of recording medium
30
from supply tray
70
and onto guide ramp
140
, which guides the sheet of recording medium
30
into alignment opposite outlet orifices
200
. A generally cylindrical combination support and transport member
240
is also disposed opposite print head
160
for supporting recording media
30
beneath print head
160
and for transporting recording media
30
past print head
160
in direction of arrow
243
as print head
160
ejects ink drops
210
onto recording media
30
. In order to transport recording media past print head
160
, combination support and transport member
240
is rotatable in the direction illustrated by an arrow
245
by a motor (not shown) disposed in housing
50
.
Referring to
FIGS. 2
,
3
,
4
and
5
, disposed in housing
50
is a platform
250
located near print head
160
and aligned with combination support and transport member
240
for supporting a plurality of side-by-side heaters
260
thereon. Each heater
260
, which is affixed to platform
250
, may be a resistance heater, microwave heater or a radiant heater or any combination thereof In the case when heater
260
is a resistance heater, the heater
260
comprises a material, such as copper, or any other suitable material which rises in temperature when an electrical current is supplied to the material. In the case when heater
260
is a microwave heater, the heater
260
comprises a suitable microwave transmitter. Also, when heater
260
is a radiant heater, the heater
260
may include a tubular quartz infra-red lamp, a quartz tube heater, a metal rod heater or an ultraviolet heater. In order to suitably heat ink marks
40
, the heat output from each heater
260
will be a function of recording media speed, type of recording media and the like. By way of example only, and not by way of limitation, heat output from each heater
260
may be between approximately zero watts/mm
2
and approximately
100
watts/mm
2
.
As best seen in
FIGS. 5 and 6
, side-by-side heaters
260
are spaced-apart and arranged parallel one-to-another in a row extending the length of print head
160
. A length “L
1
” and a width “W
1
” of each heater
260
as well as a pitch “P
1
” (i.e., spacing) between adjacent heaters
260
are preferably chosen so as to optimize fabrication cost and drying precision. In this manner, control of ink drying is precise and optimized. In the preferred embodiment of the invention, the length “L
1
” is 0.125 inches (0.318 centimeters), the width “W
1
” is 0.020 inches (0.051 centimeters) and the pitch “P
1
” is 0.050 inches (0.127 centimeters). However, it should be appreciated that the length “L
1
”, width “W
1
” and pitch “P
1
” are limited mainly by the ability to micro-fabricate heaters
260
and thereafter affix heaters
260
to platform
250
. Moreover, each heater
260
is shown as having a rectangular transverse cross-section; however, each heater
260
may assume any convenient transverse cross-section or overall shape and all such alternative configuratiors of heaters
260
are contemplated within the breadth and scope of the present invention. In addition, there may a thermal insulator (not shown) interposed between adjacent heaters
260
to prevent thermal “cross-talk” between any adjacent heaters
260
. Preventing thermal cross-talk between any adjacent heaters
260
more efficiently directs the heat directly to the intended ink marks
40
. In this regard, the heater array may be fabricated in a thermally insulating substrate to minimize thermal “cross-talk”.
Referring again to
FIGS. 5 and 6
, also affixed to platform
250
is a plurality of side-by-side sensors
270
. Sensors
270
may be based on conventionally known technology or any suitable method for sensing temperature of recording medium
30
. In addition, sensors
270
may be RTD's, thermocouples, or other devices for sensing moisture by means of electrical conductivity or other suitable method. As may be appreciated from the disclosure hereinabove, the location on recording media where an ink mark
40
is present has a different temperature (elevated temperature) than where ink mark
40
is absent. Sensor
270
advantageously senses those locations of elevated temperature to identify locations on recording media
30
having ink marks. Side-by-side sensors
270
are spaced-apart and arranged parallel one-to-another in a row extending the length of print head
160
. A length “L
2
” and a width “W
2
” of each sensor
270
as well as a pitch “P
2
” (i.e., spacing) between adjacent sensors
270
are preferably chosen so as to sense or detect as small a population of ink marks
40
as possible. In this manner, sensing of ink marks
40
is precise and optimized. In the preferred embodiment of the invention, the length “L
2
” is 0.12 inch (0.3 centimeters), the width “W
2
” is 0.04 inch (0.1 centimeters) and the pitch “P
2
” is 0.050 inches (0.127 centimeters). However, it should be appreciated that the length “L
2
”, width “W
2
” and pitch “P
2
” are limited mainly by the ability to micro-fabricate sensors
270
and thereafter affix sensors
270
to platform
250
. Moreover, each sensor
270
is shown as having a rectangular transverse cross-section; however, each sensor
270
may assume any convenient transverse cross-section or overall shape and all such alternative configurations of sensors
270
are contemplated within the breadth and scope of the present invention. In addition, the length L
2
, width W
2
of each sensor
270
and pitch P
2
need not be equivalent to the length L
1
, width W
1
and pitch P
1
of heaters
260
.
Referring to
FIGS. 2
,
3
and
7
, previously mentioned controller
220
is electrically connected to each thermal resistor
190
for electrically selectively actuating resistors
190
. In this regard, controller
220
selectively supplies an electrical pulse train, generally referred to as
280
, comprising a plurality of electrical pulses
290
. Pulses
290
are selectively supplied to thermal resistors
190
according to electrical output signals received from image input source
230
, which is electrically connected to controller
220
. Pulses
290
are illustrated as square-shaped, however, pulses
290
may take any known shape, such as triangular-shaped or sinusoidally-shaped. Moreover, controller
220
controls pulse amplitude “PA”, pulse width “PW” and time between pulses “ΔT” in order to control volume of ink drop
210
ejected out outlet orifice
200
. For example, each time controller
220
supplies a pulse
290
to thermal resistor
190
, one ink drop
210
is ejected out outlet orifice
200
. In addition, controller
220
is electrically connected to each sensor
270
for receiving output signals therefrom each time a sensor
270
senses presence of ink mark
40
. Controller
220
in turn transmits the output signal received from sensors
270
to respective ones of heaters
260
. In this manner, sensors
270
inform heaters
260
of the locations of ink marks
40
on recording media
30
for activating selected ones of heaters
260
in order to dry only those locations having ink marks
40
. Platform
250
is disposed opposite bottom surface
35
of recording media
30
, so that heaters
260
and sensors
270
that are affixed thereto come into contact with bottom surface
35
. In this manner, heaters
260
transfer heat through recording media
30
to ink marks
40
by means of conduction through recording media
30
. After ink marks
40
comprising image
20
are printed and dried, support and transport member
240
transports recording media
30
to a downwardly-canted slide
295
interposed between platform
250
and outlet opening
80
. Printed recording media
30
is received by slide
295
and slides therealong until it passes through outlet opening
80
and lands in output tray
90
to be retrieved by the operator of printer
10
. In addition, previously mentioned controller
220
is connected, such as by means of first electrical conducting wire
296
, to motor
110
for controlling operation of motor
110
. Controller
220
is also connected, such as by means of second electrical conducting wire
297
, to print head
160
for controlling operation of print head
160
. In addition, controller
220
is connected to heaters
260
and sensors
270
, such as by means of third electrical conducting wire
298
and fourth electrical conducting wire
299
, respectively, for controlling operation of heaters
260
and sensors
270
. Moreover, controller
220
is connected, such as by means of a fifth electrical conducting wire (not shown), to a motor (also not shown) for rotating support and transport member
240
in the direction of arrow
245
.
Referring to
FIG. 8
, there is shown a second embodiment of the present invention. According to this second embodiment of the present invention, heaters
260
and sensors
270
are disposed opposite top surface
33
of recording medium
30
. In this second embodiment, heaters
260
and sensors
270
are spaced-apart from recording medium
30
by a predetermined distance, rather than being in contact with recording media
30
, so as to avoid smearing ink marks
40
as recording media
30
is transported past print head
160
. In this manner, heat is transferred to ink marks
40
by means of radiation. Also, according to this second embodiment of the present invention, a base
300
contacting bottom surface
35
of recording media
30
is provided to support recording media
30
as recording media
30
travels past heaters
260
and sensors
270
. An advantage of this second embodiment of the present invention, is that risk of scorching of recording media
30
is reduced because heaters
260
do not come into contact with recording media
30
.
Referring to
FIG. 9
, there is shown a third embodiment of the present invention. According to this third embodiment of the present invention, a pair of sensors
310
a
and
310
b
disposed opposite top surface
33
of recording media
30
are connected to a carriage
320
that is slidably movable along an elongate rail
330
extending the width of recording media
30
and parallel to print head
160
. In this regard, carriage is adapted for reciprocating movement along rail
330
by means of a motor (not shown) coupled to carriage
320
. Carriage
320
moves along rail
330
transversely with respect to recording media in the direction of double-headed arrow
335
. Preferably, as carriage
320
moves in one direction transversely with respect to recording media
30
, sensor
310
a
will sense any ink marks in its path and as carriage
320
moves in the other direction transversely with respect to recording media
30
, sensor
310
b
will sense other ink marks in its path. An advantage of this third embodiment of the present invention is that fewer sensors are required for increased cost savings.
Referring to
FIG. 10
, there is shown a fourth embodiment of the present invention. This fourth embodiment of the present invention is substantially similar to the third embodiment of the present invention, except that the pair of sensors
310
a/b
is replaced by a single sensor
340
connected to carriage
320
. Single sensor
320
senses ink marks
40
each time reciprocating carriage
320
traverses recording media
30
. An advantage of this fourth embodiment of the present invention is that number of sensors is reduced even further as compared to the third embodiment of the present invention for even greater cost savings.
Referring to
FIG. 11
, there is shown a fifth embodiment of the present invention. This fifth embodiment of the present invention is substantially similar to the first embodiment of the present invention, except that sensors
270
are absent. Rather, electrical pulses
290
that are transmitted to thermal resistors
190
are also transmitted to respective ones of heaters
260
for informing heaters
260
of which thermal resistors
190
have been actuated. In this manner, heaters
260
will heat only those locations of recording media
30
having ink marks formed by the actuation of respective ones of thermal resistors
190
.
Referring to
FIG. 12
, a control algorithm, generally referred to as
350
, may be present in controller
220
for controlling heaters
260
, based on inputs from sensors
270
, information about local print density, and other global parameters. In this regard, control algorithm
350
comprises sensor
270
in printer
10
that measures ambient humidity, as illustrated by block
360
. Similarly there is another sensor
270
in printer
10
that measures the ambient temperature, as illustrated by block
370
. Printer is also provided with information about recording media type, as illustrated by block
380
, and the ink type, as illustrated by block
390
. These global values for recording media type and ink type are input into their respective transfer functions. In other words, ambient humidity is input into transfer function G
1
. In addition, ambient temperature is input into transfer function G
2
, also media type is input into transfer function G
3
. Finally, ink type is input into transfer function G
4
. The outputs of the transfer functions G
1
through G
4
are summed at the summing junction
400
.
Referring again to
FIG. 12
, the output of junction
400
is fed into the summing junction
410
. Thus, the first of three inputs into summing junction
410
is the output of junction
400
. The second of three inputs into the summing junction
410
is the output of a transfer function
420
which operates on known information about what was just printed in each of printed microzones (i, j) on recording media
30
, as illustrated by block
430
. The third input into summing junction
410
is described below.
Still referring to
FIG. 12
, the output from junction
410
is fed into a power transfer function
440
. The output of power transfer function
440
is amplified in order to drive the microheaters
260
, for each microheater i and each swath j, as illustrated by block
450
. It may be appreciated by a person of ordinary skill in the art, that each heater (i) could be composed of a plurality of separately controllable subheaters i
1
, i
2
, i
3
, and so forth. For the purposes of the embodiment disclosed herein, each heater (i) is a unitary or single unit.
Referring again to
FIG. 12
, as a result of the power output from the microheaters
260
, and after the next swath advance, as shown at block
460
, the swath (j−1) will have a resultant moisture and temperature to be measured in each measurement microzone (i, j−1) on recording media
30
, as illustrated by block
470
. The output of block
470
is fed into the difference junction
480
. In addition, the output of a target moisture/temperature block
490
is fed into difference junction
480
. Target block
490
is a function of the information pulled out of the control loop at node
500
. In addition, the parameters of target block
490
may include user-supplied settings, or other printing parameters.
Referring yet again to
FIG. 12
, the output of difference junction
480
is fed into the summing junction
510
. In addition, the output of transfer function
520
is fed into summing junction
510
. The transfer function
520
receives information from the difference junction
530
, which compensates for differences in print density between the current swath density at block
430
and the previous swath density at block
540
. The output of the summing junction
510
is fed into the summing junction
410
, and as such is the third input into the summing junction
410
. Moreover, it should be noted that algorithm
350
can be generalized to include regions of more than one increment away from the critical zones (i, j) in order to take into account the spreading of moisture and heat from the microzone in question. For example, algorithm
350
can incorporate additional feedback from the regions bounded by zones (i, j−2), (i, j−3), and so forth, or (i+1, j−1), (i−1, j−1), and so forth, as determined to be useful.
With reference to
FIG. 12
, what is enabled, in summary, is a precision media drying system that applies the optimal energy in each printed area of the media (i.e., microzones i,j). The drying system adapts to changes in environmental conditions (e.g., moisture and temperature). In addition, the system learns to compensate for errors and variations in controlling moisture and temperature on a precision basis across the width of recording media
30
.
Turning now to
FIGS. 12 and 13
, there is shown a representative first calibration curve
450
illustrating change in energy AE as a function of ambient relative humidity “RH”. Such a first calibration curve
550
may be stored in controller
220
. It is known that relative humidity is a function of both temperature and humidity. Therefore, sensors
270
may not only sense presence of ink marks
40
, but also detect ambient temperature and humidity and transmit those values to controller
220
. Controller
20
may then calculate relative humidity and use that value of relative humidity and first calibration curve
550
to determine the amount of energy to add to ink marks
40
in order dry ink marks
40
in view of the existing ambient relative humidity “RH”. Of course, there may be a family of first curves
550
depending on the type of recording media being printed. It may be appreciated that, in general, one would expect “diminishing returns” on applied energy ΔE versus evaporation rate a function of RH. In other words, more energy would have to be pumped in for a given change in RH, as the RH increases, for a given desired end moisture level in the media. Curve
550
represents this relationship of “diminishing returns”, and could also represent the calibration curve implemented in the present invention. An alternative to first calibration curve
550
is a second calibration curve
560
. Second calibration curve
560
represents another type of implementation where the curve
560
is broken into segments, and the additional energy applied ΔE is constant over a given range or RH. This in general may b e more cost effective to implement than first calibration curve
550
. A value ΔE
s
represents a maximum or allowable level of applied energy ΔE in order to avoid damage (e.g., paper scorching hazard) to printer
10
. It is noted that ambient RH is just one factor in the control loop represented by blocks
360
and
370
of FIG.
12
.
It may be appreciated from the description hereinabove that an advantage of the present invention is that use of the present invention saves energy. This is so because heat is applied only to those locations on recording media
30
having ink marks
40
rather than to locations of recording media
30
not having ink marks
40
as well as those locations having ink marks
40
.
Another advantage of the present invention is that amount of heat applied to ink marks
40
varies depending on the amount of ink thereat sensed by sensors
270
. This is accomplished by varying the pulse amplitude “PA”, pulse width “PW” and time “ΔT” between electrical pulses
290
supplied to heaters
260
. That is, operation of heaters
260
can be individually modulated by controller
220
for more precise drying of ink marks
40
.
Still another advantage of the present invention is that speed of printing is increased. This is so because speed of recording media past print head
160
can increase for a given print density, such as when sensors
270
sense no or few ink marks
40
present in a print line.
Yet another advantage of the present invention is that scorching of recording media
30
is avoided. This is so because only those locations on recording media
30
having ink marks
40
are heated. Locations not having ink marks
40
or fewer ink marks
40
are not heated, thereby reducing risk of scorching.
A further advantage of the present invention is that use thereof avoids use of the large volumes of gas and large amounts of energy needed to heat the gas, as in blower-type ink drying systems. This is so because the ink marks are dried by use of conductive, microwave or radiant heating rather than heated gas blown onto ink marks
40
.
While the invention has been described with particular reference to its preferred embodiments, 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 embodiments without departing from the invention. For example, print head
160
need not be a page-width print head. Rather, print head
160
may be reciprocating-type print head adapted for reciprocating movement transversely across width of recording media
30
. In this case, pair of sensors
310
a/b
or single sensor
340
may be connected to the reciprocating print head. As a further example, each individual sensor
270
,
310
a/b
and
340
may communicate its sensing information by means of radio transmission to be received by a radio receiver connected to each of heaters
260
. In this case, when each sensor transmits its radio signal of a predetermined frequency indicative of location and volume of ink at ink marks
40
, respective heaters
260
receive the radio signals and are energized to variably heat the ink marks
40
. As a further example, a piezoelectric print head rather than a thermal inkjet print head
160
may be used, if desired. As an additional example, it may be appreciated by a person of ordinary skill in the art that the inventive concept disclosed herein is not confined to printing mechanisms, but is also useable in any web feeding application where fluids are being applied and it is desired to dry or cure the fluid at an accelerated rate. Such applications of the inventive concept would be in manufacturing of paper, fabrics, adhesives, and the like.
Therefore, what is provided is a printer having precision ink drying capability and method of assembling the printer.
PARTS LIST
ΔE
s
. . . maximum allowed change in energy
G
1
. . . transfer function
G
2
. . . transfer function
G
3
. . . transfer function
G
4
. . . transfer function
L . . . length of heater
P . . . pitch of heaters
PA . . . pulse amplitude
PW . . . pulse width
ΔT . . . time between pulses
W . . . width of each heater
10
. . . printer
20
. . . image
30
. . . recording media
33
. . . top surface of recording media
35
. . . bottom surface of recording media
40
. . . ink marks
50
. . . housing
60
. . . inlet opening
70
. . . supply tray
80
. . . outlet opening
90
. . . output tray
100
. . . picker mechanism
110
. . . motor
120
. . . axle
130
. . . roller
140
. . . guide ramp
150
. . . spring
160
. . . print head
170
a/b/c/d
. . . ink modules
180
. . . ink ejection chamber
190
. . . thermal resistor
200
. . . outlet orifice
210
. . . ink drop
220
. . . controller
230
. . . image input source
240
. . . support and transport member
243
. . . arrow
245
. . . arrow
250
. . . platform
260
. . . heaters
270
. . . sensors
280
. . . pulse train
290
. . . electrical pulses
295
. . . slide
296
. . . first conducting wire
297
. . . second conducting wire
298
. . . third conducting wire
299
. . . fourth conducting wire
300
. . . base
310
a/b
. . . pair of sensors
320
. . . carriage
330
. . . rail
335
. . . arrow
340
. . . single sensor
350
. . . control algorithm
360
. . . measured ambient humidity block
370
. . . measured ambient temperature block
380
. . . recording media type information
390
. . . known ink type information
400
. . . summing junction
410
. . . summingjunction
420
. . . transferjunction
430
. . . known “just printed” swath density of microzone (i,j
440
. . . power transfer function
450
. . . heaters are driven for each heater (i) and swath (j)
460
. . . swath advance
470
. . . measured moisture or temperature
480
. . . difference junction
490
. . . target moisture/temperature
500
. . . node
510
. . . summingjunction
520
. . . transfer function
530
. . . difference junction
540
. . . previous swath density
550
. . . first calibration curve
560
. . . second calibration curve
Claims
- 1. A printer having precision ink drying capability, comprising:a. a print head adapted to form an ink mark at a location on a recording media; b. a dryer associated with said print head for drying the ink mark; and c. a controller coupled to said dryer for controllably operating said dryer, so that said dryer selectively dries only the ink mark.
- 2. The printer of claim 1, further comprising a sensor associated with said dryer for sensing the location of the ink mark on the recording media.
- 3. The printer of claim 2, wherein said sensor is adapted to move transversely with respect to said recording media.
- 4. The printer of claim 2, wherein said controller is coupled to said sensor for informing said dryer of the location of the ink mark on the recording media as said sensor senses the ink mark.
- 5. The printer of claim 1, wherein said controller is coupled to said print head for informing said dryer of the location of the ink mark on the recording media as said print head forms the ink mark.
- 6. The printer of claim 1, wherein said dryer comprises a resistance heater.
- 7. The printer of claim 1, wherein said dryer comprises a microwave heater.
- 8. The printer of claim 1, wherein said dryer comprises a radiant heater.
- 9. A printer having precision ink drying capability, comprising:a. a print head adapted to eject a plurality of ink drops for forming a plurality of ink marks at a plurality of locations on a recording medium; b. a plurality of heaters disposed near said print head for heating the ink marks to dry the ink marks; and c. a controller connected to each of said heaters for selectively energizing said heaters according to the locations of the ink marks on the recording media, so that said heaters dry only the locations having ink marks.
- 10. The printer of claim 9, further comprising a sensor adapted to reciprocate transversely with respect to said recording media for sensing the locations of the ink marks on the recording media, said sensor being coupled to said heaters.
- 11. The printer of claim 9, further comprising a plurality of sensors coupled to respective ones of said heaters for sensing the locations of the ink marks on the recording media.
- 12. The printer of claim 11, wherein said controller is connected to each of said sensors for selectively informing said heaters of the locations of the ink marks on the recording media as said sensors sense the ink marks.
- 13. The printer of claim 9, wherein said controller is connected to said print head for informing said heaters of the locations of the ink marks on the recording media as said print head forms the ink marks on the recording media.
- 14. The printer of claim 9, wherein each of said heaters is a resistance heater.
- 15. The printer of claim 9, wherein each of said heaters is a microwave heater.
- 16. The printer of claim 9, wherein each of said heaters is a radiant heater.
- 17. A printer having precision ink drying capability, comprising:a. a print head defining a plurality of ink ejection chambers therein, each ink ejection chamber adapted to eject a plurality of ink drops therefrom for forming a plurality of ink marks at a plurality of locations on a recording media; b. a plurality of spaced-apart, parallel heaters aligned in a row transversely with respect to the recording media for heating the ink marks to dry the ink marks; and c. a controller electrically connected to each of said heaters for generating a plurality of electrical pulses selectively energizing said heaters according to the locations of the ink marks on the recording media, so that said heaters dry only the locations having ink marks.
- 18. The printer of claim 17, further comprising:a. an elongate bar disposed near said heaters and extending transversely with respect to the recording media; and b. a sensor slidably engaging said bar and adapted to slidably reciprocate along said bar transversely with respect to the recording media for generating an electrical pulse upon sensing each of the locations of the ink marks on the recording media, said sensor being coupled to each of said heaters for transmitting the electrical pulses to said heaters corresponding to the locations of the ink marks.
- 19. The printer of claim 17, further comprising a plurality of sensors electrically connected to respective ones of said heaters for generating a plurality of electrical pulses upon sensing the locations of the ink marks on the recording media.
- 20. The printer of claim 19, wherein said controller is electrically connected to each of said sensors for receiving the electrical pulses generated by said sensors and for transmitting the electrical pulses to respective ones of said heaters for informing said heaters of the locations of the ink marks on the recording media as said sensors sense the ink marks.
- 21. The printer of claim 17, wherein said controller is electrically connected to each of said ink ejecting chambers for generating a plurality of electrical pulses for selectively electrically energizing said ink ejection chambers and for electively informing said heaters of the ink ejection chambers electrically energized, so that said heaters are informed of the locations of the ink marks on the recording media as said ink ejection chambers form the ink marks.
- 22. The printer of claim 17, wherein each of said heaters is a thermal resistance heater.
- 23. The printer of claim 17, wherein each of said heaters is a microwave heater.
- 24. The printer of claim 17, wherein each of said heaters is an infra-red radiant heater.
- 25. A method of assembling a printer having precision ink drying capability, comprising the steps of:a. providing a print head adapted to form an ink mark at a location on a recording media; b. coupling a dryer associated to the print head for drying the ink mark; and c. coupling a controller to the dryer for controllably operating the dryer, so that the dryer selectively dries only the ink mark.
- 26. The method of claim 25, further comprising the step of coupling a sensor to the dryer for sensing the location of the ink mark on the recording media.
- 27. The method of claim 26, further comprising the step of adapting the sensor to move transversely with respect to the recording media.
- 28. The method of claim 26, further comprising the step of coupling the controller to the sensor for informing the dryer of the location of the ink mark on the recording media as the sensor senses the ink mark.
- 29. The method of claim 25, further comprising the step of coupling the controller to the print head for informing the dryer of the location of the ink mark on the recording media as the print head forms the ink mark.
- 30. The method of claim 25, wherein the step of coupling the dryer comprises the step of coupling a resistance heater.
- 31. The method of claim 25, wherein the step of coupling the dryer comprises the step of coupling a microwave heater.
- 32. The method of claim 25, wherein the step of coupling the dryer comprises the step of coupling a radiant heater.
- 33. A method of assembling a printer having precision ink drying capability, comprising the steps of:a. providing a print head adapted to eject a plurality of ink drops for forming a plurality of ink marks at a plurality of locations on a recording medium; b. disposing a plurality of heaters near the print head for heating the ink marks to dry the ink marks; and c. connecting a controller to each of the heaters for selectively energizing the heaters according to the locations of the ink marks on the recording media, so that the heaters dry only the locations having ink marks.
- 34. The method of claim 33, further comprising the step of adapting a sensor to reciprocate transversely with respect to the recording media for sensing the locations of the ink marks on the recording media, the sensor being coupled to the heaters.
- 35. The method of claim 33, further comprising the step of coupling a plurality of sensors to respective ones of the heaters for sensing the locations of the ink marks on the recording media.
- 36. The method of claim 35, further comprising the step of connecting the controller to each of the sensors for selectively informing the heaters of the locations of the ink marks on the recording media as the sensors sense the ink marks.
- 37. The method of claim 33, further comprising the step of connecting the controller to the print head for informing the heaters of the locations of the ink marks on the recording media as the print head forms the ink marks on the recording media.
- 38. The method of claim 33, wherein the step of disposing the plurality of heaters comprises the step of disposing a plurality of resistance heaters.
- 39. The method of claim 33, wherein the step of disposing the plurality of heaters comprises the step of disposing a plurality of microwave heaters.
- 40. The method of clam 33, wherein the step of disposing the plurality of heaters comprises the step of disposing a plurality of radiant heaters.
- 41. A method of assembling a printer having precision ink drying capability, comprising the steps of:a. providing a print head defining a plurality of ink ejection chambers therein, each ink ejection chamber adapted to eject a plurality of ink drops therefrom for forming a plurality of ink marks at a plurality of locations on a recording media; b. aligning a plurality of spaced-apart, parallel heaters in a row transversely with respect to the recording media for heating the ink marks to dry the ink marks; and c. electrically connecting a controller to each of the heaters for generating a plurality of electrical pulses selectively energizing the heaters according to the locations of the ink marks on the recording media, so that the heaters dry only the locations having ink marks.
- 42. The method of claim 41, further comprising the steps ofa. disposing an elongate bar near the heaters and extending transversely with respect to the recording media; and b. slidably engaging a sensor with the bar, the sensor being adapted to slidably reciprocate along the bar transversely with respect to the recording media for generating an electrical pulse upon sensing each of the locations of the ink marks on the recording media, the sensor being coupled to each of the heaters for transmitting the electrical pulses to the heaters corresponding to the locations of the ink marks.
- 43. The method of claim 41, further comprising the step of electrically connecting a plurality of sensors to respective ones of the heaters for generating a plurality of electrical pulses upon sensing the locations of the ink marks on the recording media.
- 44. The method of claim 43, further comprising the step of electrically connecting the controller to each of the sensors for receiving the electrical pulses generated by the sensors and for transmitting the electrical pulses to respective ones of the heaters for informing the heaters of the locations of the ink marks on the recording media as the sensors sense the ink marks.
- 45. The method of claim 41, further comprising the step of electrically connecting the controller to each of the ink ejecting chambers for generating a plurality of electrical pulses for selectively electrically energizing the ink ejection chambers and for electively informing the heaters of the ink ejection chambers electrically energized, so that the heaters are informed of the locations of the ink marks on the recording media as the ink ejection chambers form the ink marks.
- 46. The method of claim 41, wherein the step of aligning the plurality of spaced-apart, parallel heaters comprises the step of aligning a plurality of thermal resistance heaters.
- 47. The method of claim 41, wherein the step of aligning the plurality of spaced-apart, parallel heaters comprises the step of aligning a plurality of microwave heaters.
- 48. The method of claim 41, wherein the step of aligning the plurality of spaced-apart, parallel heaters comprises the step of aligning a plurality
US Referenced Citations (13)