1. Field of Invention
This invention is directed to systems, methods and structures for dissipating heat in fluid ejector heads.
2. Description of Related Art
A variety of systems, methods and structures are conventionally used to dissipate heat in a thermal fluid ejector head. The thermal fluid ejector heads of fluid ejection devices, such as, for example, ink jet printers, generate significant amounts of residual heat as the fluid is ejected by heating the fluid to the point of vaporization. This residual heat will change the performance, and ultimately the ejection quality, if the excess heat remains within the fluid ejector head. Changes in ejector performance are normally manifested by a change in the drop size, firing sequence, or other related ejection metrics. Such ejection metrics desirably remain within a controllable range for acceptable ejection quality. During lengthy operation or heavy coverage ejection, the temperature of the thermal fluid ejector head can exceed an allowable temperature limit. Once the temperature limit is exceeded, a slow down or cool down period is normally used to maintain the ejection quality.
Many fluid ejection devices, such as, for example, printers, copiers and the like, improve throughput by improving thermal performance. One technique to improve fluid ejector head performance is to divert excess heat into the fluid being ejected. Once the fluid being ejected has exceeded a predetermined temperature, the hot fluid is ejected from the fluid ejector head. During lengthy operation or heavy coverage ejection, this technique is also susceptible to temperatures in the fluid ejector head exceeding an allowable temperature limit.
Another technique is to use a heat sink to store heat, or conduct heat away, from the fluid ejector head. Typically, heat sinks are made from copper, aluminum or other materials having high thermal conductivity to remove heat from the thermal fluid ejector head. U.S. patent application Ser. No. 10/600,507, which is incorporated herein by reference in its entirety, discloses various exemplary embodiments of such heat sinks molded from a polymer mixed with at least one thermally-conductive filler material.
Heat sinks, however, add additional weight, size, cost and/or energy usage to the fluid ejector head. Each of these becomes disadvantageous when heat sinks are applied to fluid ejector heads that are translated past a receiving medium. Additionally, many fluids typically employed in fluid ejector heads, such as inks, use solvents and/or salts which are likely to corrode aluminum, copper and other like heat sink materials.
Other systems, methods and structures usable to conduct heat away from thermal fluid ejector heads include manufacturing and/or molding various print cartridge and fluid ejector carriage elements and components from thermally-conductive materials, to include a polymer or a polymer material mixed with at least one thermally-conductive filler material. U.S. patent application Ser. No. ______ (Attorney Docket No. 116594) and U.S. patent application Ser. No. 10/629,606, each incorporated herein by reference in its entirety, disclose various embodiments for thermally-conductive fluid ejector carriages and fluid ejector print cartridge components molded from polymers.
This invention provides systems, methods and structures that dissipate heat in a thermal fluid ejector head.
This invention separately provides systems, methods and structures that transfer heat from a fluid ejector head into a fluid ejector carriage device used to support the fluid ejector head.
This invention separately provides systems, methods and structures that obtain better thermal conductivity between a thermally-conductive fluid ejector carriage device, including such devices molded from a thermally-conductive polymer material, and at least one structure upon which a thermally-conductive fluid ejector carriage device translates. In various exemplary embodiments, such at least one structure includes, but is not limited to, a carriage guide rod and/or carriage guide rail.
In various exemplary embodiments of the systems, methods and structures according to this invention, thermally-conductive polymer components are molded to increase the surface area available to conduct heat away from a fluid ejector module. Using highly thermally-conductive polymers in molding and manufacturing various fluid ejector print cartridge and fluid ejector carriage elements yields certain advantages over the manufacture of these elements from traditionally highly thermally-conductive materials, such as aluminum and copper. Individual components molded from highly thermally-conductive polymers are typically smaller in size, and lighter in weight, resulting in lower energy usage in operation while still achieving high levels of heat dissipation. Additionally, thermally-conductive polymer components are less susceptible than are aluminum, copper and other traditional highly thermally-conductive materials to the corrosive effects of the solvents and/or salts that are often contained in the fluids, such as inks, that are ejected by thermal fluid ejector heads.
In various exemplary embodiments of the systems, methods and structures according to this invention, individual structures and/or devices are manufactured or molded to facilitate sufficient contact between adjoining elements to provide a thermally-conductive flow path adequate to dissipate heat during increasingly lengthy operation, or more intense periods of heavy coverage ejection, to maintain the temperature in the fluid ejector module within allowable limits, thus assuring highest ejection quality.
To achieve even greater output rates from fluid ejector head printing systems, while maintaining desired print quality, greater heat dissipation methodologies are desirable. The systems, methods and structures by which heat is dissipated from the fluid ejector module through various thermally-conductive elements, including components of fluid ejector printer cartridges and fluid ejector carriage devices, are extended to various other components which include, but which are not limited to, structures upon which the fluid ejector carriage device translates, such as, for example fluid ejector carriage guide rods and/or carriage guide rails, and supporting structures.
In various exemplary embodiments of the systems, methods and structures according to this invention, a thermally-conductive fluid ejector carriage device molded from a polymer material is used to transfer heat generated by at least one fluid ejector module to the relatively larger surface area of at least one such structure upon which the fluid ejector carriage device translates.
In various exemplary embodiments, the systems, methods and structures according to this invention provide at least one thermally-conductive interface between the fluid ejector carriage device and the structure upon which the fluid ejector carriage device translates, such as, for example, a thermally-conductive tube-like carriage rod guide, usable to dissipate heat from the thermally-conductive fluid ejector carriage device. In various exemplary embodiments, the systems, methods and structures according to this invention provide at least one thermally-conductive structure upon which the fluid ejector carriage device translates, such as, for example, a thermally-conductive carriage guide rod, with properties that allow the thermally-conductive structure to readily dissipate heat to surrounding ambient air.
In various exemplary embodiments of the systems, methods and structures according to this invention, heat is transferred along a thermally-conductive path from the fluid ejector module through the thermally-conductive fluid ejector carriage device to at least one thermally-conductive interface, or tube-like carriage rod guide, and further to at least one thermally-conductive structure, or carriage guide rod, to facilitate heat dissipation through conduction and/or convection.
In various exemplary embodiments of the systems, methods and structures according to this invention, the relatively large surface area of the at least one thermally-conductive structure provides increased area through which heat can dissipate to surrounding ambient air than is available from any individual thermally-conductive component. Additional heat transfer, and resultant heat dissipation, is accomplished through a “fanning” motion of the thermally-conductive fluid ejector carriage device and the at least one thermally-conductive interface as the at least one thermally-conductive interface translates along the at least one thermally-conductive structure.
In various exemplary embodiments of the systems and methods according to this invention, heat transfer between at least one thermally-conductive tube-like carriage rod guide and at least one thermally-conductive carriage guide rod is facilitated by contact between at least one thermally-conductive carriage rod guide bearing and the at least one thermally-conductive carriage guide rod. This contact facilitates conduction directly to at least one thermally-conductive carriage guide rod. Additionally, contact between the at least one thermally-conductive carriage rod guide bearing and the at least one thermally-conductive carriage guide rod facilitates trapping a thin volume of air for dissipating heat through convection.
In various exemplary embodiments of the systems, methods and structures according to this invention, contact between the at least one thermally-conductive carriage rod guide bearing and the at least one thermally-conductive carriage guide rod is augmented using compliant, thermally-conductive pads, and/or phase change or other thermally-conductive heat sink compounds, and/or other like devices or materials usable to enhance the thermal path between the at least one thermally-conductive carriage rod guide bearing and the at least one thermally-conductive carriage guide rod while not impeding fluid ejector carriage motion.
These and other features and advantages of the disclosed embodiments are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems, methods and structures according to this invention.
Various exemplary embodiments of the invention will be described in detail, with reference to the following figures, wherein:
The following description of various exemplary embodiments of the fluid ejection systems according to this invention may refer to and/or illustrate one specific type of fluid ejection system, a thermal ink jet printer, for the sake of clarity and familiarity. However, it should be appreciated that the principles of this invention, as outlined and/or discussed below, can be equally applied to any known or later-developed fluid ejection system, wherein a moving fluid ejector carriage translates along at least structure, beyond the ink jet printer specifically discussed herein.
Various exemplary embodiments of the systems, methods and structures according to this invention enable heat dissipation from fluid ejector heads, such as those found in, for example, thermal ink jet printers, copiers, facsimile machines and/or other devices containing moving carriages that translate in varying, most often reciprocating, directions along at least one structure and that thermally eject fluid onto a receiving medium. In various exemplary embodiments, heat is dissipated through various components, and specifically at least one structure along which a fluid ejector carriage device translates and/or at least one structure which provides a thermally-conductive interface and/or connection between the fluid ejector carriage device and such structure. For clarity and simplicity in description, reference is made to at least one carriage rod guide and at least one carriage guide rod fashioned from thermally-conductive elements as the exemplary interface and exemplary structure upon which the fluid ejector carriage device translates. It should be appreciated, however, that these represent only exemplary embodiments to which the systems, methods and structures according to this invention are not limited.
In various exemplary embodiments of the systems, methods and structures according to this invention, a polymer, or a polymer material mixed with at least one thermally-conductive filler material, is used to form various thermally-conductive components for heat transfer from a fluid ejector module along a heat dissipation path which includes thermally-conductive fluid ejector print cartridge elements, a thermally-conductive fluid ejector carriage device, at least one thermally-conductive like carriage rod guide, and at least one thermally-conductive carriage guide rod to surrounding ambient air. The incorporated (Attorney Docket No. 116594), '507 and '606 applications disclose various embodiments for various intermediate thermally-conductive components that can be combined to form a heat flow path from the fluid ejector module to at least one thermally-conductive carriage guide rod according to this invention.
In various exemplary embodiments, the systems, methods and structures according to this invention provide at least one thermally-conductive tube-like carriage rod guide and at least one thermally-conductive carriage guide rod manufactured and/or molded from thermally-conductive materials, which include, but which are not limited to, aluminum, copper, and/or a polymer, or polymer material having at least one thermally-conductive filler material, with properties that allow the carriage guide rod to more readily dissipate heat to the surrounding ambient air.
In various exemplary embodiments of the systems, methods and structures according to this invention, heat is transferred by conduction through a thermally-conductive path from the fluid ejector head through the thermally-conductive fluid ejector carriage device and then, for example, through at least one thermally-conductive tube-like carriage rod guide and conformal carriage rod guide bearings mounted on, or molded into, one or both ends of the at least one thermally-conductive tube-like carriage rod guide, to at least one thermally-conductive carriage guide rod, where the bearings are in sufficient contact with the at least one thermally-conductive carriage guide rod to facilitate surface-to-surface heat conduction but not so much in contact that motion of the fluid ejector carriage device along the at least one thermally-conductive carriage guide rod is impeded.
In various exemplary embodiments, the systems, methods and structures according to this invention transfer heat to be dissipated along the at least one thermally-conductive carriage guide rod using convection through a thin volume of air trapped, for example, between an internal surface of at least one thermally-conductive tube-like carriage rod guide bounded on at least one end by at least one thermally-conductive carriage rod guide bearing, and the surface of the at least one thermally-conductive carriage guide rod. In various exemplary embodiments of the systems, methods and structures according to this invention, this thin volume of trapped air is sheared across the surface of a thermally-conductive carriage guide rod during motion of the fluid ejector carriage device and the thermally-conductive tube-like carriage rod guide along the thermally-conductive carriage guide rod. This shearing enhances heat transfer across the interface between the thermally-conductive tube-like carriage rod guide and the thermally-conductive carriage guide rod, resulting in increased heat transfer to surrounding ambient air based on the thermal contact between the thermally-conductive carriage guide rod and the ambient air.
Additional heat transfer, and resultant heat dissipation, is accomplished through a “fanning” motion of the thermally-conductive fluid ejector carriage and the at least one thermally-conductive tube-like carriage rod guide as the at least one thermally-conductive tube-like carriage rod guide translates along the at least one thermally-conductive carriage guide rod.
In various exemplary embodiments of the systems, methods and structures according to this invention, at least one carriage guide rod is manufactured and/or molded using any highly thermally-conductive materials, including, for example, but not limited to, aluminum, copper, or certain thermally-conductive polymers. The thermal conductivity of aluminum is, by example, about 100-150 W/m° C. The thermal conductivity of the highly thermally-conductive polymers is in the range of about 10-100 W/m° C. or greater.
Thermally-conductive components, such as fluid ejector print cartridges, fluid ejector carriages, carriage rod guides, carriage rod guide bearings and carriage guide rods are used to carry heat away from fluid ejector module containing the heater element of a thermal fluid ejector head, allowing the fluid ejector head to operate in an acceptable temperature range for extended periods of time. Dissipating heat away from the fluid ejector module allows the thermal fluid ejector head to operate at temperatures cool enough to enable consistent high quality fluid ejection.
In various exemplary embodiments according to this invention, highly thermally-conductive polymers are used for the carriage rod guide and carriage guide rod material. In various exemplary embodiments, such highly thermally-conductive polymers, include base polymers mixed with a variety of filler materials. For example, one such polymer material is COOL POLY™ made by Cool Polymers Inc. Specifically, COOL POLY E200™ polymer material is an injection-moldable, liquid crystalline polymer (LCP) based material having a thermal conductivity of about 60 W/m° C. Other companies such as Polyone, LDP Engineering Plastics, RPP Company, GE and Dupont, have developed highly thermally-conductive polymers that may also be used in forming carriage rod guides and carriage guide rods according to this invention.
Typical filler materials include graphite fibers and ceramic materials such as boron, nitride, and aluminum nitride fibers. In various exemplary embodiments, blends of highly thermally-conductive polymers that have high thermal conductivity use graphite fibers formed from petroleum pitch base material. Typical base materials for the polymers include LCP, polyphenylene sulfide and polysulfone.
In various exemplary embodiments of the systems, methods and structures according to this invention, a thermal fluid ejector print cartridge 200 contains at least one thermal fluid ejector head 210. While depicted in
In various exemplary embodiments of the systems, methods and structures according to this invention, at least one thermally-conductive carriage rod guide 120 is molded integrally with, or separately attached to, the thermally-conductive fluid ejector carriage 100 such that a sufficient heat flow path is established to transfer heat from the thermal fluid ejector head 210 through the thermally-conductive fluid ejector carriage 100 and into the thermally-conductive carriage rod guide 120. In various exemplary embodiments, heat is further transferred from the thermally-conductive carriage rod guide 120 into the thermally-conductive carriage guide rod 140, as will be explained in greater detail below.
FIGS. 2 illustrates an exemplary thermally-conductive carriage rod guide 120, thermally-conductive carriage guide rod 140 and thermally-conductive carriage rod guide bearings 130 and 135 usable with various exemplary embodiments of the systems, methods and structures according to this invention.
The thermally-conductive carriage guide rod 140 is depicted in
It should be further appreciated that the structure upon which the fluid ejector carriage translates according to this invention is not, in any way, limited to an exemplary thermally-conductive carriage guide rod 140 and an exemplary thermally-conductive carriage rod guide 120 as depicted in
In various exemplary embodiments of the systems, methods and structures according to this invention, the ends of the thermally-conductive carriage rod guide 120 are enclosed with thermally-conductive carriage rod guide bearings 130 and 135 that are separate structures mounted onto the ends of, or integral structures that are molded with, the thermally-conductive carriage rod guide 120.
In various exemplary embodiments, the thermally-conductive carriage rod guide bearings 130 and 135 are designed and manufactured such that openings 132 and 137 in the thermally-conductive carriage rod guide bearings 130 and 135, respectively, generally have similar cross-sectional shapes to the cross-sectional shape of the thermally-conductive carriage guide rod 140. In various exemplary embodiments, the thermally-conductive carriage rod guide bearings 130 and 135 are held in tight relationship to the thermally-conductive carriage guide rod 140. Such exemplary design provides a medium for conducting heat based on contact between the thermally-conductive carriage rod guide bearings 130 and 135 and the thermally-conductive carriage guide rod 140.
In various exemplary embodiments of the systems, methods and structures according to this invention, the space or gap 150 between an internal surface of the thermally-conductive carriage rod guide 120 and the surface of the thermally-conductive carriage guide rod 140 contains a thin layer of air that is enclosed by the thermally-conductive carriage rod guide bearings 130 and 135 to form a thin volume of trapped air that dissipates heat through convection. The trapped air is heated by transferring heat from an internal surface of the thermally-conductive carriage rod guide 120 as the thermally-conductive carriage rod guide 120 conducts heat from the thermally-conductive fluid ejector carriage 100. The thin volume of trapped air is aggressively sheared across the surface of the thermally-conductive carriage guide rod 140 as the thermally-conductive fluid ejector carriage 100, and specifically, the thermally-conductive carriage rod guide 120, translates along the thermally-conductive carriage guide rod 140 in a direction A.
In various exemplary embodiments according to this invention, this trapped volume of air is mixed in a complex air flow pattern as the assembly of the thermally-conductive carriage rod guide 120 and the thermally-conductive carriage rod guide bearings 130 and 135 translates along the thermally-conductive carriage guide rod 140 in a direction A. This complex air flow pattern results in increased conduction and/or convection as heat is transferred from the thermally-conductive carriage rod guide 120 and the thermally-conductive carriage rod guide bearings 130 and 135 across the thin space or gap 150, into at least one thermally-conductive carriage guide rod 140. Heat is then dissipated along the at least one thermally-conductive carriage guide rod 140 and to the surrounding ambient air through convection.
In various exemplary embodiments of the systems, methods and structures according to this invention, the thermally-conductive carriage rod guide bearings 130 and 135 are molded from any thermally-conductive material, which can include, for example, aluminum, copper and/or any thermally-conductive polymer material. In various exemplary embodiments of the systems, methods and structures according to this invention, compliant, thermally-conductive pad materials, phase change or other thermally-conductive heat sink compounds, and/or other like devices or materials usable to conduct heat, are added to enhance the thermal path, and/or to seal the interface, between the thermally-conductive carriage rod guide bearings 130 and 135 and the thermally-conductive carriage guide rod 140. It should be appreciated that any device and/or material usable to enhance the thermally conductive path between the thermally-conductive carriage rod guide bearings 130 and 135 and the thermally-conductive carriage guide rod 140 may be added as long as the motion of the thermally-conductive fluid ejector carriage device 100 along the thermally-conductive carriage guide rod 140 is not impeded.
It should be appreciated that other separate structures and/or devices can be provided between the thermally-conductive fluid ejector carriage 100 and the thermally-conductive carriage guide rod 140 to provide, augment, or enhance the heat flow path between the thermally-conductive fluid ejector carriage 100, and the thermally-conductive carriage guide rod 140 such that sufficient heat transfer between the thermally-conductive fluid ejector carriage 100, and the thermally-conductive carriage guide rod 140 is obtained.
While this invention has been described in conjunction with the exemplary embodiments outlined above, various alternatives, modifications, variations, improvements, and/or substantial equivalents, whether known or that are, or may be, presently unforeseen, may become apparent to those having at least ordinary skill in the art. Accordingly, the exemplary embodiments of the invention, as set forth above, are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention. Therefore, the invention is intended to embrace all known or later-developed alternatives, modifications, variations, improvements, and/or substantial equivalents.