Patent Application
20110180526
This application deals generally with image-producing devices, and more specifically, with solid-ink based image-producing devices.
Solid ink (also known as phase-change ink) image-producing devices conventionally employ ink supplied in solid form through a drop tube, either as pellets or as colored-ink sticks. In general, phase change inks are in solid form at ambient temperature, but the ink must be converted to liquid form and transported to the print head, where the ink can be ejected as drops or jets. Generally, this phase change is accomplished by melting the solid ink in a solid-ink melter tank. A melter assembly for large ink sticks includes a heating element with openings, which allow liquefied solid ink to pass through is disclosed in U.S. application Ser. No. 12/362,579 filed Jan. 30, 2009. Another U.S. application Ser. No. 12/638,863, filed Dec. 15, 2009, discloses a solid-ink melter apparatus including a heating element designed as an array of spaced apart fins, with a number of heat transfer elements passing through the fins. Liquefied solid ink is subsequently supplied to a print head of the image-producing device, forming jets of ink that print on the target media. When the ink droplets contact the printing media, they quickly solidify to create an image in the desired pattern.
Typically, heating elements in the solid-ink melter tank heat the air present in the solid-ink melter tank. In the absence of a forced airflow path, the hot air rises from the solid-ink melter tank into the drop tube, which heats the metering valve and the solid ink in the solid-ink supply tank. As the drop tube's temperature rises, some of the incoming solid ink partially melts and clings to the drop tube and the associated components, such as metering valves, leading to clogging of the drop tube and the associated components.
An electric cooling fan supplying cool air to the drop tube and the associated components may offer a solution to the problem. Sudden power failure, however, can cause the electric cooling fan to stop, leading to clogging of the metering valve, the solid-ink supply tank, the drop tube, and the associated components.
Therefore, a need exists for a mechanism to maintain the solid-ink drop tube and the associated components at a lower temperature.
The present disclosure provides embodiments of an airflow system for a solid-ink melter tank. The airflow system includes an inlet for providing airflow into the solid-ink melter tank, and an outlet maintained at a temperature higher than the temperature of the inlet. The heated outlet promotes a convective air current; the heated air exits from the outlet and draws cool air in the inlet.
Further, an embodiment of an airflow management method for a solid-ink melter tank is disclosed. The airflow management method provides an inlet for supplying airflow to the solid-ink melter tank and an outlet maintained at a temperature higher than the temperature of the inlet for promoting a convective air current, which draws cool air into the inlet.
According to the aspects illustrated herein, an airflow system for a solid-ink melter tank is provided. The system includes a hopper for carrying the solid ink, a drop tube connected to the hopper for supplying the solid ink to the solid-ink melter tank, and a metering valve for controlling the amount of solid ink entering the solid-ink melter tank. An inlet allows air into the solid-ink melter tank and an outlet, maintained at a temperature higher than temperature of the inlet, promotes a convective air current, drawing cool air in the inlet. Multiple heating elements for melting the solid ink are disposed in the form of parallel plates within the solid-ink melter tank. Liquefied solid ink accumulates in a collection area, below the heating elements, within the solid-ink melter tank.
The figures described below set out and illustrate a number of exemplary embodiments of the disclosure. Throughout the drawings, like reference numerals refer to identical or functionally similar elements. The drawings are illustrative in nature and are not drawn to scale.
The following detailed description is made with reference to the figures. Exemplary embodiments are described to illustrate the subject matter of the disclosure, not to limit its scope, which is defined by the appended claims.
As used throughout the disclosure, the term “solid-ink melter tank” refers to a container for retaining liquefied solid ink. The solid ink may either be melted by multiple heating elements present in the solid-ink melter tank or be melted elsewhere and retained in the solid-ink melter tank in liquid phase.
To prevent drop tube clogging in conventional solid-ink melter tanks, the present disclosure describes a system and method for promoting a convective air current in a solid-ink melter tank. The solid-ink melter tank includes an inlet for allowing airflow in the solid-ink melter tank, a heated outlet for promoting exit of hot air, and multiple heating elements for supplying heat for melting the solid ink. The heated outlet promotes a convective air current in the solid-ink melter tank and facilitates exit of hot air through the heated outlet and intake of cool air from the inlet. The inlet may also function as a drop tube by allowing air as well as solid ink into the solid-ink melter tank. The convective air current prevents heating of the inlet as well as the drop tube, thus preventing clogging of the inlet by partial melting of solid ink.
Furthermore, the outlet 106 is fabricated from a material with high thermal conductivity, such as aluminum, while the inlet 102 is fabricated from a material having low thermal conductivity, such as plastic. The outlet 106 may be maintained at a temperature higher than the temperature of the inlet 102 either by thermal conduction with the solid-ink melter tank 104 or by an external electric heating element. Those of skill in the art will recognize the class of materials generally referred to as “thermally conductive” and will be able to select a suitable material from that class to fit a particular application.
In another embodiment, the airflow and the solid ink enter the solid-ink melter tank 104 through two different openings in the solid-ink melter tank 104. The inlet 102 supplies airflow and a drop tube supplies solid ink to the solid-ink melter tank 104. In an embodiment of the present disclosure, an opening in the solid-ink melter tank 104 serves as the inlet 102. The inlet 102 and the drop tube may be coaxial according to another embodiment. In further embodiments, the outer surface of the outlet 106 may be covered with an insulating material such as mineral wool to prevent heat loss to the surroundings.
An outlet 214 to the solid-ink melter tank 208 is maintained at a temperature higher than temperature of inlet 210, by an electric heating element 216, leading to a convective air current. Multiple heating elements 218, placed within the solid-ink melter tank 208, heat the solid ink 204. The heating elements 218, heated by an electric heater 220, connect to a power source via a power cord 222. The solid ink 204 melts upon making contact with the multiple heating elements 218. Air, exposed to the heating elements 218, also becomes heated. The hot air exits through the heated outlet 214, leading to intake of cool air from the inlet 210 through air vents 226. Liquefied solid ink 224 drips off the bottom of the heating elements 218 to a collection area 228 below.
As shown in
In several embodiments, the outlet 214 is taller than the inlet 210. The taller, heated outlet 214 ensures correct direction of airflow, with cool air entering the solid-ink melter tank 208 via the shorter inlet 210 and hot air leaving the solid-ink melter tank 208 via the taller outlet 214.
In certain embodiments, the outlet may be taller than the inlet. Also, in some embodiments, heat loss to the surroundings is lowered by insulating the outer surface of the outlet with an insulating material such as mineral wool. In one implementation, the outlet fabrication material has a high thermal conductivity while the inlet fabrication material has a low thermal conductivity. In another implementation, the outlet and the inlet are cylindrical pipes. In some embodiments, more than one inlet and outlet of the solid-ink melter tank may be present.
Those skilled in the art will understand that the steps set out in the discussion above may be combined or altered in specific adaptations of the disclosure. The illustrated steps are set out to explain the embodiment shown, and it should be anticipated that ongoing technological development will change the manner in which particular functions are performed. These depictions do not limit the scope of this disclosure, which is determined solely by reference to the appended claims.
Moreover, the solid-ink melter tank 104 shown in
The specification has described an airflow system for a solid-ink melter tank utilized for melting solid ink. The specification has set out a number of specific exemplary embodiments, but persons of skill in the art will understand that variations in these embodiments will naturally occur in the course of embodying the subject matter of the disclosure in specific implementations and environments. For example, the inlet supplying airflow and the drop tube allowing solid ink in the solid-ink melter tank may be coaxial with each other or be present as separate openings in the solid-ink melter tank. Furthermore, the heating elements utilized for melting the solid ink may be present as a grid. A first set of heating elements is formed of parallel plates placed one millimeter apart from each other. The first set of heating elements is placed perpendicular to a similarly constructed second set of heating elements, resulting in the grid. It will further be understood that such variations and others as well, fall within the scope of the disclosure. Neither those possible variations nor the specific examples set above are set out to limit the scope of the disclosure. Rather, the scope of disclosure is defined solely by the claims set out below.
Systems and methods disclosed herein may be implemented in equipment employing other granular materials, such as resin, alloys, paraffin wax, soap, gels, oil, or plastics. Apparatus of the disclosure can be implemented in image-producing devices employing solid ink, to prevent clogging of inlet 102 supplying airflow as well as solid ink into the solid-ink melter tank 104. Method steps of the disclosure can be performed by utilizing heated outlets 106 for promoting a convective air current in the solid-ink melter tank 104. Multiple heating elements 108 provide heat to melt the solid ink, which drips off the bottom of heating elements 108 to accumulate in a collection area 110, for further supply to the print head. The convective air current prevents clogging by drawing cool air through the inlet 102. Any of the foregoing may be incorporated in solid ink printers, copiers, scanners, fax machines or in a combination of them.
