Information
-
Patent Grant
-
6607259
-
Patent Number
6,607,259
-
Date Filed
Thursday, October 11, 200122 years ago
-
Date Issued
Tuesday, August 19, 200320 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Gordon; Raquel Yvette
- Stewart, Jr.; Charles W.
Agents
-
CPC
-
US Classifications
Field of Search
US
- 347 18
- 347 19
- 347 85
- 347 86
- 347 87
- 347 17
- 347 23
- 347 63
- 347 6
- 347 7
- 219 544
- 392 451
-
International Classifications
-
Abstract
A thermal ink jet printer having enhanced heat removal capability and method of assembling the printer. The thermal inkjet printer includes a thermal inkjet print bead adapted to hold an ink body therein. A heating element is adapted to be in fluid communication with the ink body for generating heat to heat the ink body. A vapor bubble forms in the ink body to eject an ink drop when the heating element causes the ink body to reach a predetermined temperature. Presence of the vapor bubble forces on ink drop out the printer to form an image on a recording medium. A conductive heat removal structure is in thermal communication with the heating element and is also in fluid communication with the ink body. Heat generated by the heating element is transferred from the heating element and into the heat removal structure. The heat removal structure then surrenders the heat to the ink body, which functions as an “infinite” heat sink. In this manner, the heat removal structure provides enhanced heat removal of heat generated by the heating element.
Description
BACKGROUND OF THE INVENTION
This invention generally relates to printer apparatus and methods and more particularly relates to a thermal ink jet printer having enhanced heat removal capability and method of assembling the printer, the printer being adapted for high speed printing and increased thermal resistor lifetime.
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.
In the case of thermal inkjet printers, a print head structure comprises a single or plurality of ink cartridges each having a nozzle plate that includes a plurality of nozzles. Each nozzle is in communication with a corresponding ink ejection chamber formed in the print head cartridge. Each ink ejection chamber in the cartridge receives ink from an ink supply reservoir containing, for example, yellow, magenta, cyan or black ink. In this regard, the ink supply reservoir may be internal to the cartridge and thus define an “on board” or internal ink reservoir. Alternatively, each cartridge may be fed by conduit from an “off-axis” or remote ink supply reservoir. In either event, each ink ejection chamber is formed opposite its respective nozzle so ink can collect between the ink ejection chamber and the nozzle. Also, a resistive heater is disposed in each ink ejection chamber and is connected to a controller, which selectively supplies sequential electrical pulses to the heaters for actuating the heaters. When the controller supplies the electrical pulses to the heater, the heater heats a portion of the ink adjacent the heater, so that the portion of the ink adjacent the heater vaporizes and forms a vapor bubble. Formation of the vapor bubble pressurizes the ink in the ink ejection chamber, so that an ink drop ejects out the nozzle to produce a mark on a recording medium positioned opposite the nozzle.
During printing, the print head is moved across the width of the recording medium as the controller 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 prints another swath of information in the manner mentioned hereinabove. This process is repeated until the desired image is printed on the recording medium. Such 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.
In addition, in order to increase print resolution, current practice is to place the nozzles and respective heaters relatively close together on the print head. Moreover, in order to increase printer speed, width of the printing swath is increased by including a relatively large number of nozzles and corresponding heaters in the print head. To further aid in increasing printer speed, the heaters are typically fired at a relatively high frequency.
However, it has been observed that such efforts to increase print resolution and printer speed may result in excessive heat generation in the print head. Excessive heat generation in the print head is undesirable. In this regard, bubble formation in the thermal inkjet print head is directly influenced by temperature and excessive heat generation interferes with proper bubble formation (e.g., size of vapor bubble). Also, excessive heat generation may cause the ink drop to be prematurely ejected. Premature ejection of the ink drop may in turn lead to printing anomalies (e.g., unintended ink marks) appearing on the recording medium. In addition, excessive heat generation may cause unintended vapor bubbles to accumulate in the ink, thereby blocking the exit nozzle and interfering with ejection of the ink drop when required. Further, excessive heat generation may ultimately shorten operational lifetime of the heater.
Techniques for cooling thermal inkjet print heads to reduce excessive heat generation are known. One such technique is disclosed by U.S. Pat. No. 6,120,139 titled “Ink Flow Design To Provide Increased Heat Removal From An Inkjet Printhead And To Provide For Air Accumulation” issued Sep. 19, 2000 in the name of Winthrop Childers, et al. and assigned to the assignee of the present invention. The Childers, et al. patent discloses an inkjet printer having a print head assembly that includes a substrate. Formed on the substrate are ink ejection chambers and their respective ink ejection heater resistors. Flow directors direct ink flow onto the substrate and heat transfers from the substrate into the ink as the ink flows toward the drop ejection chambers where the warm ink is ejected onto recording media. In this manner, the flow directors help channel the ink flow path to maximize heat transfer to the ejected ink droplets. Thus, it would appear the ejected ink droplet acts as a heat sink for removing heat from the substrate and hence from the print head assembly. However, the ink droplet itself has limited capacity or capability to act as a heat sink because the volume of the ink droplet is necessarily limited. Although the Childers, et al. device performs its function as intended, it is nonetheless desirable to enhance heat removal beyond the heat removal capability afforded by the limited volume of the ejected ink droplet. Thus, enhancing heat removal in the Childers, et al. device would increase printer speed and heater lifetime.
Therefore, what is needed is a thermal ink jet printer having enhanced heat removal capability and method of assembling the printer, the printer being adapted for high speed printing and increased thermal resistor lifetime.
SUMMARY OF THE INVENTION
The present invention resides in a thermal inkjet printer having enhanced heat removal capability, comprising a thermal inkjet print head adapted to hold an ink body, the print head including a heating element adapted to be in fluid communication with the ink body; a heat removal structure in thermal communication with the heating element for transferring heat from the heating element to the ink body; and a controller coupled to the heating element.
According to an aspect of the present invention, a thermal inkjet printer includes a thermal inkjet print head adapted to hold an ink body therein. The print head comprises an ink cartridge including a heat conductive substrate and a resistive heating element coupled to the substrate. The cartridge also includes a face plate having a nozzle orifice positioned opposite the heating element. The heating element is adapted to be in fluid communication with the ink body for generating heat to heat a portion of the ink body near the heating element. A vapor bubble forms in the ink body between the heating element and the nozzle orifice when the portion of the ink body near the heating element reaches a predetermined temperature. Presence of the vapor bubble forces an ink drop out the nozzle orifice to form an image on a recording medium. A conductive heat removal structure is in thermal communication with the heating element and is also in fluid communication with the ink body. Heat is transferred from the heating element, through the substrate and into the heat removal structure. The heat removal structure then surrenders the heat to the ink body, which functions as an “infinite” heat sink in order to provide enhanced heat removal.
A feature of the present invention is the provision of a heat removal structure for enhanced removal of heat generated by the heating element.
An advantage of the present invention is that printing speed is increased.
Another advantage of the present invention is that use thereof allows for proper bubble formation (e.g., size of vapor bubble).
Still another advantage of the present invention is that risk of premature ejection of ink drops is reduced.
Yet another advantage of the present invention is that risk of accumulation of unintended vapor bubbles in the ink is reduced.
Moreover, another advantage of the present invention is that use thereof prolongs operational lifetime of the heating element.
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 view in perspective, with parts removed for clarity, of a thermal inkjet printer according to the present invention, the printer comprising a print head including a plurality of ink cartridges;
FIG. 2
is a view in elevation of a first embodiment of a representative one of the cartridges;
FIG. 3
is a view along section line
3
—
3
of FIG.
2
.
FIG. 4
is a view in elevation of a second embodiment of a representative one of the cartridges;
FIG. 5
is a view in elevation of a third embodiment of a representative one of the cartridges;
FIG. 6
is a view in elevation of a fourth embodiment of a representative one of the cartridges;
FIG. 7
is a view in elevation of a fifth embodiment of a representative one of the cartridges;
FIG. 8
is a view in elevation of a sixth embodiment of a representative one of the cartridges;
FIG. 9
is a perspective view in elevation of a seventh embodiment of a representative one of the cartridges;
FIG. 10
is a fragmentation view along section line
10
—
10
of
FIG. 9
;
FIG. 11
is a perspective view in partial elevation of an eighth embodiment of a representative one of the cartridges;
FIG. 12
is a fragmentation view taken along section line
12
—
12
of
FIG. 11
;
FIG. 13
is a perspective view in partial elevation of a ninth embodiment of a representative one of the cartridges;
FIG. 14
is an exploded perspective view in partial elevation, and with parts removed for clarity, of the ninth embodiment of the cartridge;
FIG. 15
is a fragmentation view of the ninth embodiment of the cartridge;
FIG. 16
is a perspective view in partial elevation of a tenth embodiment of a representative one of the cartridges;
FIG. 17
is an exploded perspective view in partial elevation, and with parts removed for clarity, of the tenth embodiment of the cartridge;
FIG. 18
is an exploded perspective view in partial elevation, and with parts removed for clarity, of an eleventh embodiment of a representative one of the cartridges;
FIG. 19
is a fragmentation view of the eleventh embodiment of the cartridge;
FIG. 20
is an exploded perspective view in partial elevation, and with parts removed for clarity, of a twelfth embodiment of a representative one of the cartridges;
FIG. 21
is a fragmentation view of the twelfth embodiment of the cartridge; and
FIG. 22
is a fragmentation view in perspective of the twelfth embodiment of the cartridge.
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
FIG. 1
, there is shown a thermal inkjet printer, generally referred to as
10
, for printing an image
20
on a recording medium
30
. Recording medium
30
may be a reflective recording medium (e.g., paper) or a transmissive recording medium (e.g., transparency) or other type of recording medium suitable for receiving image
20
. Printer
10
comprises a housing
40
having a first opening
45
and a second opening
47
therein for reasons disclosed presently. Disposed in housing
40
is an upright frame
50
defining an aperture
55
therein for reasons disclosed presently. Connected to frame
50
is a first motor
60
, which may be a stepper motor, engaging an elongate spindle
70
for rotating spindle
70
. Fixedly mounted on spindle
70
are a plurality of rollers
80
that rotate as spindle
70
is rotated by first motor
60
. Also connected to frame
50
is an elongate slide bar
90
oriented parallel to spindle
70
. Slidably engaging slide bar
90
is an ink cartridge holder
100
adapted to hold a plurality of generally rectangularly-shaped ink cartridges
110
a
,
110
b
,
110
c
and
110
d
. Ink cartridges
110
a
,
110
b
,
110
c
and
110
d
contain colorants such as yellow, magenta, cyan and black ink, respectively.
Referring again to
FIG. 1
, a belt drive assembly, generally referred to as
120
, is also connected to frame
50
. Belt drive assembly
120
comprises a plurality of oppositely disposed rollers
130
a
and
130
b
rotatably connected to frame
50
. One of the rollers, such as roller
130
b
, engages a reversible second motor
140
, which may be a stepper motor, for rotating roller
130
b
. In this case, roller
130
a
is configured to freely rotate while roller
130
b
is rotated by second motor
140
. Wrapped around rollers
130
a
and
130
b
and spanning the distance therebetween is a continuous belt
150
affixed to ink cartridge holder
100
. Thus, it may be appreciated from the description hereinabove, that operation of second motor
140
will cause roller
130
b
to rotate because roller
130
b
engages second motor
140
. Belt
150
will rotate as roller
130
b
rotates because belt
150
engages roller
130
b
. Of course, roller
130
a
will also rotate as belt
150
rotates because roller
130
a
engages belt
150
and is freely rotatable. In this manner, cartridge holder
100
will slide to-and-fro or reciprocate along slide bar
90
as reversible second motor
140
rotates belt
150
first in a clockwise direction and then in a counter-clockwise direction. This to-and-fro reciprocating motion allows cartridge holder
100
and cartridges
110
a/b/c/d
held by cartridge holder
100
to traverse the width of recording medium
30
to print a swath of information on recording medium
30
. After printing the swath of information, spindle
70
and associated rollers
80
rotate in the manner disclosed hereinabove to advance recording medium
30
the width of the swath and print another swath of information. This process is repeated until the desired image
20
is printed on recording medium
30
. Also connected to frame
50
is a controller
160
. Controller
160
is electrically coupled, such as by means of an electricity flow path or wire
170
a
, to ink cartridges
110
a/b/c/d
for selectively controlling operation of ink cartridges
110
a/b/c/d
, so that ink cartridges
110
a/b/c/d
eject an ink drop
180
on demand (see FIG.
2
). Moreover, as shown in
FIG. 1
, controller
160
is electrically coupled, such as by means of an electricity flow path or wire
170
b
, to second motor
140
for controlling operation of second motor
140
. In addition, controller
160
is electrically coupled to first motor
60
, such as by means of another electricity flow path or wire (now shown), for controlling operation of first motor
60
. Further, controller
160
is coupled to a picker mechanism (not shown) belonging to printer
10
for controlling operation of the picker mechanism. The picker mechanism “picks” individual sheets of recording medium
30
from a recording medium supply bin or tray
190
insertable into housing
40
through second opening
47
. In this regard, the picker mechanism will “pick” and then feed an individual sheet of recording medium
30
from supply tray
190
, through aperture
55
and into engagement with rollers
80
, so that the sheet of recording medium
30
is interposed between ink cartridges
110
a/b/c/d
and rollers
80
. Thus, it may be appreciated from the description hereinabove, that controller
160
controls synchronous operation of first motor
60
, second motor
140
, the picker mechanism and ink cartridges
110
a/b/c/d
for producing desired image
20
on recording medium
30
. Input to controller
160
may be from an image processor, such as a personal computer or scanner (not shown).
Turning now to
FIGS. 2 and 3
, there is shown a first embodiment of a representative one of ink cartridges
110
a/b/c/d
, such as ink cartridge
110
a
. Ink cartridge
110
a
comprises a cartridge shell
200
including a first sidewall
210
a
disposed opposite and parallel to a second sidewall
210
b
and further including a top wall
210
c
integrally connected to sidewalls
210
a
and
210
b
. Spanning sidewalls
210
a
and
210
b
and integrally connected thereto and disposed opposite and parallel to top wall
210
c
is a bottom wall or nozzle plate
210
d
having a plurality of aligned nozzle orifices
220
a
and
220
b
formed therethrough and arranged in parallel rows. Of course, integrally connected to sidewalls
210
a
and
210
b
, top wall
210
c
and nozzle plate
210
d
is a front wall (not shown). Further, integrally connected to sidewalls
210
a
and
210
b
, top wall
210
c
and disposed parallel to the front wall is a rear wall
225
. Thus, it may be understood from the description immediately hereinabove, that sidewalls
210
a
and
210
b
, top wall
210
c
, nozzle plate
210
d
, the front wall and rear wall
225
together define a chamber
230
for receiving an ink body
240
therein.
Still referring to
FIGS. 2 and 3
, disposed in chamber
230
is a rectangularly-shaped heat conductive die or substrate
250
, which defines a top surface
255
and a bottom surface
257
opposite top surface
255
. Substrate
250
is spaced apart from nozzle plate
210
d
to define a gap therebetween to allow space for formation of a vapor bubble
260
, in a manner disclosed presently. Substrate
250
is preferably formed of silicon dioxide, but may be formed of plastic, metal, glass, or ceramic if desired. In addition, substrate
250
is supported by a base
265
coupled to nozzle plate
210
d
. Coupled to bottom surface
257
are a plurality of aligned first heating elements or first thin-film thermal resistors
270
a
spaced along the length of rectangularly-shaped substrate
250
and disposed opposite respective ones of nozzle orifices
220
a
. Moreover, coupled to bottom surface
257
are a plurality of aligned second heating elements or second thin-film thermal resistors
270
b
spaced along the length of rectangularly-shaped substrate
250
and disposed opposite respective ones of nozzle orifices
220
b
. Each resistor
270
a/b
is electrically connected to previously mentioned controller
160
, so that controller
160
selectively controls flow of electric current to resistors
270
a/b
. Of course, when controller
160
supplies electricity to any of resistors
270
a/b
, the resistor
270
a/b
generates heats, thereby heating ink adjacent to resistor
270
a/b
to form vapor bubble
260
. In other words, controller
160
controllably supplies a plurality of electrical pulses to resistors
270
a/b
for selectively energizing resistors
270
a/b
so that vapor bubble
260
forms. Vapor bubble
260
will in turn pressurize ink body
240
to force or squeeze ink drop
180
out nozzle orifice
220
a/b
disposed opposite resistor
270
a/b
. Such a thermal resistor
270
a/b
and associated electrical circuitry is disclosed more fully in U.S. patent application Ser. No. 08/962,031, filed Oct. 31, 1997, titled “Ink Delivery System for High Speed Printing” and assigned to the assignee of the present invention, the disclosure of which is hereby incorporated by reference. Also disposed in chamber
230
and connected to sidewalls
210
a/b
is a filter
280
bifurcating chamber
230
into an ink reservoir region
285
and a firing chamber region
287
. The purpose of filter
280
is to filter particulate matter from ink body
240
, so that the particulate matter does not migrate to and block nozzle orifices
220
a/b
. Thus, ink body
240
flows from ink reservoir region
285
, through filter
280
and into firing chamber region
287
to come into contact with resistors
270
a/b
, so that resistors
270
a/b
are in fluid communication with ink body
240
..
As previously mentioned, prior art efforts to increase print resolution and printing speed by increasing the number and density of thermal resistors on the print head and increasing firing frequency of the thermal resistors may result in excessive heat generation in the print head. Excessive heat generation in the print head interferes with proper bubble formation, prematurely ejects ink drops, causes unintended vapor bubbles to accumulate in the ink, and ultimately may shorten operational lifetime of the resistors. Therefore, it is highly desirable to remove the heat generated by the resistors in the print head after formation of the vapor bubble.
Therefore, as best seen in
FIG. 2
, a rectangularly-shaped heat removal structure
290
is connected to top surface
255
of substrate
250
. Heat removal structure
290
is made of a highly heat conductive material, such as aluminum having a thermal conductivity of approximately 119 Btu/hr ft ° zF. at 212° F. Alternatively, heat removal structure
290
may be made of a material having thermal conductivity known to increase with increasing temperature and decrease with decreasing temperature, such as potassium silicates, lead silicates, ternary carbides, ternary oxides and ternary nitrides. The width of heat removal structure
290
extends the length of substrate
250
and is preferably connected to substrate
250
by means of a suitable highly heat conductive adhesive. Moreover, it may be appreciated from the description hereinabove that the height of heat removal structure
290
may be such that heat removal structure
290
protrudes through filter
280
.
Still referring to
FIG. 2
, when a selected one of resistors
270
a/b
is energized by controller
160
, heat is transferred from resistor
270
a/b
to substrate
250
as vapor bubble
260
forms. This heat is conducted through substrate
250
to heat removal structure
290
. Heat removal structure
290
surrenders this heat to the surrounding ink body
240
. In this regard, ink body
240
has a volume of approximately 20 cubic centimeters and therefore effectively functions as an “infinite” heat sink. Although some heat leaves substrate
250
by means of ink drop
180
, the volume (e.g., between approximately 4 to 20 pico liters) of ink drop
180
is limited; therefore, the amount of heat taken away from substrate
250
by ink drop
180
is similarly limited. However, heat removal structure
290
of the present invention removes substantially more heat from substrate
250
because heat removal structure
290
delivers this heat to a substantially infinite heat sink (i.e., ink body
240
).
Referring to
FIG. 4
, a representative one of a second embodiment of ink cartridges
110
a/b/c/d
is there shown. This second embodiment ink cartridge, such as ink cartridge
110
a
, is substantially similar to the first embodiment ink cartridge, except heat removal structure
290
is a porous sintered filter material, such as stainless steel having a thermal conductivity of approximately 9.4 Btu/hr ft ° F. at 212° F. Heat removal structure
290
covers all surfaces of substrate
250
except for bottom surface
257
and extends into contact with sidewalls
210
a/b
, rear wall
225
and the front wall of cartridge
110
a
. It may be understood from the description immediately hereinabove that heat removal structure
290
serves a dual function of filtering ink body
240
as well as removing heat from substrate
250
. Therefore, heat removal structure
290
advantageously eliminates need for a separate filter member.
Referring to
FIG. 5
, a representative one of a third embodiment of ink cartridges
110
a/b/c/d
is there shown. This third embodiment ink cartridge, such as ink cartridge
110
a
, is substantially similar to the first embodiment ink cartridge, except heat removal structure
290
defines a cooling chamber
300
for receiving an aqueous coolant
305
, such as water or ink, of a predetermined temperature that may be lower than the temperature of ink body
240
. Coolant
305
contacts top surface
255
of substrate
250
so that heat is transferred from substrate
250
to coolant
305
. Heat removal structure
290
also defines a plurality of finger-like projections or protuberances
310
extending into ink body
240
and that are filled with coolant
305
. Presence of protuberances
310
increases surface area of heat removal structure
290
to enhance transfer of heat from heat removal structure
290
(and thus substrate
250
) to ink body
240
.
Referring to
FIG. 6
, a representative one of a fourth embodiment of ink cartridges
110
a/b/c/d
is there shown. This fourth embodiment ink cartridge, such as ink cartridge
110
a
, is substantially similar to the first embodiment ink cartridge, except heat removal structure
290
and substrate
250
are integrally formed as one unitary member. That is, attached or etched on top surface
255
of substrate
250
are a plurality of adjacent elongate and parallel fins
320
separated by intervening grooves
325
. Fins
320
, and associated grooves
325
, extend longitudinally along the length of rectangularly-shaped substrate
250
. Presence of fins
320
increases surface area of the unitary heat removal structure
290
and substrate
250
to enhance transfer of heat to ink body
240
.
Referring to
FIG. 7
, a representative one of a fifth embodiment of ink cartridges
110
a/b/c/d
is there shown. This fifth embodiment ink cartridge, such as ink cartridge
110
a
, is substantially similar to the first embodiment ink cartridge, except the heat removal structure comprises a first embodiment agitator
330
in the form of a rotatable propeller
340
connected, for example, to the inside of sidewall
210
a
. Propeller
340
engages a motor
335
for rotating propeller
340
. Propeller
340
is in fluid communication with ink body
240
for agitating ink body
240
so that heat transferred from substrate
250
to ink body
240
is uniformly dispersed throughout ink body
240
. Uniformly dispersing the heat throughout ink body
240
aids in removing heat from vicinity of substrate
250
. In other words, propeller
340
provides forced convection of the heat in ink reservoir region
285
and firing chamber region
287
for more enhanced heat transfer than is achievable by natural convection alone.
Referring to
FIG. 8
, a representative one of a sixth embodiment of ink cartridges
110
a/b/c/d
is there shown. This sixth embodiment ink cartridge, such as ink cartridge
110
a
, is substantially similar to the first embodiment ink cartridge, except the heat removal structure comprises a second embodiment agitator
350
in the form of an oscillatable elastic membrane
360
disposed in sidewall
210
a
of cartridge
110
a
. Membrane
360
, which may be rubber, engages a piston member
365
for extending elastic membrane
360
into ink body
240
. Piston member
365
in turn engages a piston actuator
367
that actuates piston member
365
, so that piston member
365
reciprocates in direction of double-headed arrow
368
. Membrane
360
elastically extends into ink body
240
, in an oscillatory fashion, for agitating ink body
240
so that heat transferred from substrate
250
to ink body
240
is uniformly dispersed throughout ink body
240
. Uniformly dispersing the heat throughout ink body
240
aids in removing heat from vicinity of substrate
250
. In other words, membrane
360
provides forced convection of the heat in ink reservoir region
285
and firing chamber region
287
for more enhanced heat transfer than is achievable by natural convection alone.
Referring to
FIGS. 9 and 10
, a representative one of a seventh embodiment of ink cartridges
110
a/b/c/d
is there shown. This seventh embodiment ink cartridge, such as ink cartridge
110
a
, is substantially similar to the first embodiment ink cartridge, except the heat removal structure comprises an elongate septum
370
connected to substrate
250
and nozzle plate
210
d
and interposed therebetween (similar to base
265
). Formed in septum
370
are a plurality of first recesses
375
a
and second recesses
375
b
for reasons disclosed presently. Septum
370
extends the length of rectangularly-shaped substrate
250
and runs between resistors
270
a
and
270
b
. In this manner, septum
370
partitions firing chamber region
287
into a first ink flow channel
380
a
and a second ink flow channel
380
b
. Second ink flow channel
380
b
extends parallel to first ink flow channel
380
a
. First resistor
270
a
is disposed in first recess
367
a
and second resistor
270
b
is disposed in second recess
375
b
. Moreover, disposed in first ink flow channel
380
a
and adjacent to each first resistor
270
a
is a first barrier block
410
a
(only two of which are shown), which is connected to nozzle plate
210
d
and substrate
250
. In addition, disposed in second ink flow channel
380
b
and adjacent to each second resistor
270
b
is a second barrier block
410
b
(only two of which are shown), which is connected to nozzle plate
210
d
and substrate
250
. The purpose of barrier blocks
410
a/b
is to create a pressure differential recesses
375
a/b
in order to generate an increased flow of cooling ink through recesses
375
a/b
with every firing event of the resistors
270
a/b.
Referring to
FIGS. 11 and 12
, a representative one of an eighth embodiment of ink cartridges
110
a/b/c/d
is there shown. This eighth embodiment ink cartridge, such as ink cartridge
110
a
, is substantially similar to the first embodiment ink cartridge, except heat removal structure
290
is integrally formed with substrate
250
as a unitary structure, so as to define a first tunnel
412
a
and a second tunnel
412
b
extending longitudinally along the unitary structure comprising substrate
250
and heat removal structure
290
. A pump (not shown) pumps coolant into and out of tunnels
412
a/b
in the directions illustrated by double-headed arrows
415
a
and
415
b
for removing heat from the combined substrate
250
and heat removal structure
290
.
Referring to
FIGS. 13
,
14
and
15
, a representative one of an ninth embodiment of ink cartridges
110
a/b/c/d
is there shown. This ninth embodiment ink cartridge, such as ink cartridge
110
a
, is similar to the first embodiment ink cartridge, except heat removal structure
290
comprises a rectangularly-shaped radiator assembly, generally referred to as
420
, for removing heat from substrate
250
. Radiator assembly
420
comprises a radiator block
430
connected to top surface
255
of substrate
250
. Radiator block
430
is connected to top surface
255
such as by a suitable highly conductive adhesive. Radiator block
430
includes a cover
435
and defines a serpentine-shaped ink flow channel
440
formed longitudinally in radiator block
430
. Also, radiator block
430
defines an ink inlet
445
for ingress of ink into flow channel
440
and an ink outlet
447
for exit of the ink out flow channel
440
. Flow of ink in flow channel
440
is achieved by operation of an internal first embodiment micro-pump assembly
450
, generally referred to as
450
, disposed in flow channel
440
. Micro-pump assembly
450
includes a wheel, generally referred to as
460
, that in turn includes a freely-rotatable axle
470
. Arranged around axle
470
and connected thereto are a plurality of spaced-apart magnetic spokes
480
. Surrounding spokes
480
are a plurality of electromagnets
490
for exerting an electromagnetic force on spokes
480
. Electromagnets
490
are in turn connected to electrical contacts
495
that selectively actuate electromagnets
490
. In this regard, electrical contacts
495
may be connected to controller
160
for controllably supplying electrical current to electrical contacts
495
. Electromagnets
490
are sequentially energized in a clockwise fashion, so that magnetic spokes
480
will rotate in a clockwise fashion in direction of arrow
497
due to the electromagnetic force exerted on spokes
480
. In this manner, micro-pump assembly
450
pumps ink through ink flow channel
440
for removing heat from substrate
250
. In other words, substrate
250
transfers heat from firing chamber region
287
to radiator block
430
, whereupon ink pumped through ink flow channel
440
removes the heat and delivers the heat to ink body
240
. Alternatively, serpentine-shaped ink flow channel
440
may be etched into the backside of substrate
250
, thereby eliminating need for radiator assembly
430
and requiring only cover
435
.
Referring to
FIGS. 16 and 17
, a representative one of an tenth embodiment of ink cartridges
110
a/b/c/d
is there shown. This tenth embodiment ink cartridge, such as ink cartridge
110
a
, is similar to the ninth embodiment ink cartridge, except internal micro-pump assembly
450
is absent. Rather, a pump
500
external to radiator block
430
and connected to outlet
447
pumps ink through ink flow channel
440
for removing heat from substrate
250
. The heat removed from substrate
250
is delivered by pump
500
to ink body
240
. Alternatively, serpentine-shaped ink flow channel
440
may be etched into the backside of substrate
250
, thereby eliminating need for radiator assembly
430
and requiring only cover
435
and pump
500
.
Referring to
FIGS. 18 and 19
, a representative one of an eleventh embodiment of ink cartridges
110
a/b/c/d
is there shown. This eleventh embodiment ink cartridge, such as ink cartridge
110
a
, is similar to the ninth embodiment ink cartridge, except radiator block
430
is absent and first embodiment micro-pump assembly
450
is replaced by a second embodiment micro-pump assembly, generally referred as
510
. Second embodiment micro-pump assembly
510
comprises a plurality of spaced-apart thermal resistors
520
disposed in a flow channel or groove
530
formed in top surface
255
of substrate
250
. Groove
530
extends longitudinally along substrate
250
and includes a plurality of interconnected cells
535
each including an alcove
537
for receiving resistor
520
. Each cell
535
further includes a widened portion
539
tapering into a narrowed portion
540
. Resistors
520
move ink through groove
530
by timed firing pulses and the mechanism commonly referred to in the art as differential refill. Alternatively, piezoelectric members, rather than resistors
520
, may be used if desired.
Referring to
FIGS. 20
,
21
and
22
, a representative one of a twelfth embodiment of ink cartridges
110
a/b/c/d
is there shown. This twelfth embodiment ink cartridge, such as ink cartridge
110
a
, is similar to the eighth embodiment ink cartridge, except heat removal structure
290
includes a plurality of parallel ink flow channels, such as first canals
550
a
and second canals
550
b
, running longitudinally in base
265
(or similarly septum
370
). A conductor bridge
560
a
interconnects resistor
270
a
with its associated canal
550
a
(as shown). Also, a conductor bridge
560
b
interconnects resistor
270
b
with it associated canal
550
b
(as shown). Heat generated by resistors
270
a/b
is conducted by means of heat conductor bridges
560
a/b
into canals
550
a/b
. Ink flowing along first canal
550
a
and second canal
550
b
comes into contact with heat conductor bridges
560
a/b
, so that heat conductor bridge
560
a/b
picks-up the heat generated by resistors
270
a
and
270
b
and delivers that heat to the ink in canals
550
a/b
. In this manner, the heat is delivered to ink body
240
.
It may be appreciated from the description hereinabove, that an advantage of the present invention is that printing speed is increased. This is so because transfer of heat from the print head is enhanced, thereby allowing for increased resistor firing frequency. Increased resistor firing frequency allows increased printing speed.
Another advantage of the present invention is that use thereof allows for proper bubble formation (e.g., size of vapor bubble). This is so because excessive heat generation is ameliorated by enhanced heat removal.
Still another advantage of the present invention is that risk of premature ejection of ink drops is reduced. This is so because excessive heat generation may cause the ink drop to be prematurely ejected and the present invention removes excessive heat.
Yet another advantage of the present invention is that risk of accumulation of unintended vapor bubbles in the ink is reduced. Accumulation of unintended vapor bubbles is caused by excessive heat generation and use of the present invention reduces excessive heat generation.
Moreover, another advantage of the present invention is that use thereof prolongs operational lifetime of the resistance heater. This is so because excessive heat generation damages the resistance heater over time and use of the present invention reduces excessive heat generation.
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, acoustic sound waves may be introduced into the firing chamber region for agitating the ink body to produce eddy currents in the ink body. Production of eddy currents in the ink body will tend to disperse the heat throughout the ink body. Dispersal of heat throughout the ink body enhances removal of heat from the vicinity of the thermal resistors.
Therefore, what is provided is a thermal ink jet printer having enhanced heat removal capability and method of assembling the printer, the printer being adapted for high speed printing and increased thermal resistor lifetime.
Parts List
10
. . . thermal inkjet printer
20
. . . image
30
. . . recording medium
40
. . . housing
45
. . . first opening
47
. . . second opening
50
. . . frame
55
. . . aperture
60
. . . first motor
70
. . . spindle
80
. . . rollers
90
. . . slide bar
100
. . . ink cartridge holder
110
a/b/c/d
. . . ink cartridges
120
. . . belt drive assembly
130
a/b
. . . rollers
140
. . . second motor
150
. . . belt
160
. . . controller
170
a/b
. . . electricity flow paths (wires)
180
. . . ink drop
190
. . . supply tray
200
. . . cartridge shell
210
a
. . . first sidewall
210
b
. . . second sidewall
210
c
. . . top wall
210
d
. . . nozzle plate
220
a/b
. . . nozzles orifices
225
. . . rear wall
230
. . . chamber
240
. . . ink body
250
. . . substrate
255
. . . top surface
257
. . . bottom surface
260
. . . vapor bubble
265
. . . base
270
a
. . . first resistors
270
b
. . . second resistors
280
. . . filter
285
. . . ink reservoir region
287
. . . firing chamber region
290
. . . heat removal structure
300
. . . cooling chamber
305
. . . coolant
310
. . . protuberance
320
. . . fins
325
. . . grooves
330
. . . first embodiment agitator
335
. . . propeller motor
340
. . . propeller
350
. . . second embodiment agitator
360
. . . membrane
365
. . . piston member
367
. . . piston actuator
368
. . . arrow
370
. . . septum
375
a
. . . first recess
375
b
. . . second recess
380
a
. . . first ink flow channel
380
b
. . . second ink flow channel
410
a
. . . first barrier block
410
b
. . . second barrier block
412
a
. . . first tunnel
412
b
. . . second tunnel
415
a/b
. . . arrows
420
. . . first embodiment radiator assembly
430
. . . radiator block
435
. . . cover
440
. . . ink flow channel
445
. . . inlet
447
. . . outlet
450
. . . first embodiment micro-pump assembly
460
. . . wheel
470
. . . axle
480
. . . spokes
490
. . . electromagnets
495
. . . electrical contacts
497
. . . arrow
500
. . . external pump
510
. . . second embodiment micro-pump assembly
520
. . . thermal resistors
530
. . . groove
535
. . . cells
537
. . . alcove
539
. . . widened portion
540
. . . narrowed portion
550
a
. . . first canal
500
b
. . . second canal
560
a
. . . first conductor bridge
560
b
. . . second conductor bridge
Claims
- 1. A thermal inkjet printer having enhanced heat removal capability, comprising:a. a thermal inkjet print head adapted to hold an ink body, said print head including: i. a heating element adapted to be in fluid communication with the ink body; ii. a heat removal structure in thermal communication with said heating element for transferring heat from said heating element to the ink body; and b. a controller coupled to said heating element.
- 2. The printer of claim 1, wherein said heat removal structure is porous.
- 3. The printer of claim 1, wherein said heat removal structure defines a cooling chamber therein for receiving a coolant.
- 4. The printer of claim 3, wherein said heat removal structure forms a protuberance filled with the coolant and in thermal communication with the ink chamber.
- 5. The printer of claim 1, wherein said heat removal structure comprises a fin.
- 6. The printer of claim 1, wherein said heat removal structure comprises an agitator.
- 7. The printer of claim 1, wherein said heat removal structure defines a coolant flow channel therein.
- 8. The printer of claim 7, wherein said heat removal structure comprises a pump coupled to the flow channel.
- 9. The printer of claim 7, wherein said heat removal structure comprises a heat conductor bridge interconnecting said heating element and said flow channel.
- 10. A thermal inkjet printer having enhanced heat removal capability, comprising:a. a thermal inkjet print head adapted to hold an ink body therein, said print head including: i. an resistive heating element adapted to be in fluid communication with the ink body for generating heat to heat the ink body, so that a vapor bubble forms in the ink body; ii. a heat removal structure in thermal communication with said heating element and in fluid communication with the ink body for transferring the heat from said heating element to the ink body; and b. a controller coupled to said heating element for controllably supplying a plurality of electrical pulses to said heating element for electrically energizing said heating element.
- 11. The printer of claim 10, wherein said heat removal structure comprises:a. a thermally conductive support member coupled to said heating element for supporting said heating element and for conducting the heat from said heating element and through said support member; and b. a thermally conductive heat sink coupled to said support member and in fluid communication with the ink body for transferring the heat from the support member and to the ink body.
- 12. The printer of claim 11, wherein said heat sink is porous for filtering the ink body.
- 13. The printer of claim 11, wherein said heat sink comprises an enclosure defining a cooling chamber for enclosing a thermally conductive coolant therein.
- 14. The printer of claim 13, wherein said enclosure forms a protuberance projecting into the ink body for increasing heat transfer surface area of said enclosure, the protuberance forming a cavity therein in thermal communication with the chamber, the cavity being adapted to receive the coolant.
- 15. The printer of claim 10, wherein said heat removal structure comprises a cooling fin integrally formed therewith for increasing heat transfer surface area of said heat removal structure.
- 16. The printer of claim 10, wherein said heat removal structure comprises an agitator in fluid communication with the ink body for agitating the ink body, so that the heat disperses throughout the ink body.
- 17. The printer of claim 16, wherein said agitator comprises a rotatable propeller.
- 18. The printer of claim 16, wherein said agitator comprises an oscillatable membrane.
- 19. The printer of claim 10, wherein said heat removal structure defines a coolant flow channel therein for passage of a coolant therealong.
- 20. The printer of claim 19, wherein said heat removal structure comprises a pump coupled to the flow channel for pumping the coolant along the flow channel.
- 21. The printer of claim 20, wherein said pump comprises a piezoelectric member capable of flexing in response to a plurality of timed electrical pulses transmitted to said piezoelectric member.
- 22. The printer of claim 20, wherein said pump comprises a thermal resistor unit capable of heating the coolant in response to a plurality of timed electrical pulses transmitted to said thermal resistor unit.
- 23. The printer of claim 19, wherein said heat removal structure comprises a heat conductor bridge interconnecting said heating element and the flow channel for transferring heat from said heating element and to the flow channel.
- 24. A thermal inkjet print head having enhanced heat removal capability, comprising:a. an ink jet cartridge shell adapted to hold an ink body; b. a heating element disposed in said ink cartridge shell and adapted to be in fluid communication with the ink body, and c. a heat removal structure in thermal communication with said heating element for transferring heat from said heating element and to the ink body.
- 25. The print head of claim 24, wherein said heat removal structure is porous.
- 26. The print head of claim 24, wherein said heat removal structure defines a cooling chamber therein for receiving a coolant.
- 27. The print head of claim 26, wherein said heat removal structure forms a protuberance filled with the coolant and in thermal communication with the chamber.
- 28. The print head of claim 24, wherein said heat removal structure comprises a fin.
- 29. The print head of claim 24, wherein said heat removal structure comprises an agitator.
- 30. The print head of claim 24, wherein said heat removal structure defines a coolant flow channel therein.
- 31. The print head of claim 30, wherein said heat removal structure comprises a pump coupled to the flow channel.
- 32. The print head of claim 30, wherein said heat removal structure comprises a heat conductor bridge interconnecting said heating element and the flow channel.
- 33. A method of assembling a thermal inkjet printer having enhanced heat removal capability, comprising the steps of:a. providing a heating element adapted to be in fluid communication with an ink body; b. arranging a heat removal structure so as to be in thermal communication with the heating element for transferring heat from the heating element to the ink body; and c. coupling a controller to the heating element.
- 34. The method of claim 33, wherein the step of arranging the heat removal structure comprises the step of arranging a heat removal structure that is porous.
- 35. The method of claim 33, further comprising the step of forming a cooling chamber in the heat removal structure for receiving a coolant.
- 36. The method of claim 35, further comprising the step of forming a protuberance outwardly projecting from the heat removal structure and having a hollow interior in thermal communication with the chamber, the protuberance adapted to be filled with the coolant.
- 37. The method of claim 33, further comprising the step of forming a fin on a surface of the heat removal structure.
- 38. The method of claim 33, further comprising the step of coupling an agitator to the heat removal structure.
- 39. The method of claim 33, further comprising the step of forming a coolant flow channel in the heat removal structure.
- 40. The method of claim 39, further comprising the step of coupling a pump to the flow channel.
- 41. The method of claim 39, further comprising the step of interconnecting a heat conductor bridge to the heating element and the flow channel.
- 42. A method of assembling a thermal inkjet print head having enhanced heat removal capability, comprising the steps of:a. providing an ink cartridge shell adapted to hold an ink body; b. disposing a heating element in the ink cartridge shell, the heating element adapted to be in fluid communication with the ink body; and c. arranging a heat removal structure in thermal communication with the heating element for transferring heat from the heating element to the ink body.
- 43. The method of claim 42, wherein the heat removal structure is porous.
- 44. The method of claim 42, further comprising the step of forming a cooling chamber in the heat removal structure for receiving a coolant.
- 45. The method of claim 44, further comprising the step of forming a protuberance outwardly projecting from the heat removal structure and having a hollow interior in thermal communication with the chamber, the protuberance adapted to be filled with the coolant.
- 46. The method of claim 42, further comprising the step of forming a fin on a surface of the heat removal structure.
- 47. The method of claim 42, further comprising the step of coupling an agitator to the heat removal structure.
- 48. The method of claim 42, further comprising the step of forming a coolant flow channel in the heat removal structure.
- 49. The method of claim 48, further comprising the step of coupling a pump to the flow channel.
- 50. The method of claim 48, further comprising the step of interconnecting a heat conductor bridge to the heating element and the flow channel.
US Referenced Citations (15)
Foreign Referenced Citations (2)
Number |
Date |
Country |
05146658 |
Jun 1993 |
JP |
09011469 |
Jan 1997 |
JP |