Patent Application
20110141207
The present invention relates to ink jet printing and more particularly to a condenser for use in an ink jet printer such as a continuous ink jet printer.
In ink jet printing systems the print is made up of individual droplets of ink generated at a nozzle and propelled towards a substrate. There are two principal systems: drop on demand where ink droplets for printing are generated as and when required; and continuous ink jet printing in which droplets are continuously produced and only selected ones are directed towards the substrate, the others being recirculated to an ink supply.
Continuous ink jet printers supply pressurized ink to a print head assembly, having a drop generator where a continuous stream of ink emanating from a nozzle is broken up into individual regular drops by an oscillating piezoelectric element. The drops are directed past a charge electrode where they are selectively and separately given a predetermined charge before passing through a transverse electric field provided across a pair of deflection plates. Each charged drop is deflected by the field by an amount that is dependent on its charge magnitude before impinging on the substrate whereas the uncharged drops proceed without deflection and are collected at a gutter from where they are recirculated to the ink supply for reuse. A phase measurement system is also usually present as part of deflection plate assembly and is used to ensure synchronization of deflection for the droplets. The charged drops bypass the gutter and hit the substrate at a position determined by the charge on the drop and the position of the substrate relative to the print head assembly. Typically the substrate is moved relative to the print head assembly in one direction and the drops are deflected in a direction generally perpendicular thereto, although the deflection plates may be oriented at an inclination to the perpendicular to compensate for the speed of the substrate (the movement of the substrate relative to the print head assembly between drops arriving means that a line of drops would otherwise not quite extend perpendicularly to the direction of movement of the substrate).
In continuous ink jet printing a character is printed from a matrix comprising a regular array of potential drop positions. Each matrix comprises a plurality of columns (strokes), each being defined by a line comprising a plurality of potential drop positions (e.g. seven) determined by the charge applied to the drops. Thus each usable drop is charged according to its intended position in the stroke. If a particular drop is not to be used then the drop is not charged and it is captured at the gutter for recirculation. This cycle repeats for all strokes in a matrix and then starts again for the next character matrix.
The heater in the print head assembly ensures that the viscosity of the ink, which varies with the ink temperature, is maintained at a value such that the drop generator in the print head assembly works effectively. If the ink is too viscous, because its temperature is too low, or too thin, because it is too hot, then the ink stream will not break up into suitable droplets.
Ink is delivered under pressure to the print head assembly from an ink supply system that is generally housed within a sealed compartment of a cabinet that includes a separate compartment for control circuitry and a user interface panel. The system includes a main pump that draws the ink from a reservoir or tank via a filter and delivers it under pressure to the print head assembly. As ink is consumed the reservoir is refilled as necessary from a replaceable ink cartridge that is releasably connected to the reservoir by a supply conduit. The ink is fed from the reservoir via a flexible delivery conduit to the print head assembly. Electrical power to operate the heater in the print head assembly and the drop generator are supplied by power supply system cables, typically forming part of the supply conduit The unused ink drops captured by the gutter are recirculated to the reservoir via a return conduit, typically located as part of the supply conduit, by a pump. The flow of ink in each of the conduits is generally controlled by solenoid valves and/or other like components.
As the ink circulates through the system, there is a tendency for it to thicken as a result of solvent evaporation. This is particularly a problem in relation to the recirculated ink that has been exposed to air in its passage between the nozzle and the gutter. In order to compensate for this “make-up” solvent is added to the ink as required from a replaceable solvent cartridge so as to maintain the ink viscosity within desired limits when the ink is at the correct operating temperature. This solvent may also be used for flushing components of the print head assembly, such as the nozzle and the gutter, in a cleaning cycle.
The ink supply system is generally vented out of the printer cabinet. However, it has been found that this exhaust may contain solvent and/or ink particles, which creates an undesirable mess.
In one aspect, a condensate recovery system for an ink jet printer includes an ink reservoir and a condenser. The condenser is in fluid communication with the ink reservoir and is adapted to receive exhaust from the ink reservoir and condense solvent from the exhaust. The condenser includes a fluid inlet for receiving the exhaust from the fluid reservoir, a condensing volume in fluid communication with the inlet, a vent in fluid communication with the condensing volume for venting air from the condenser and a fluid outlet for removing condensed solvent from the condenser and returning the condensed solvent to the ink reservoir. A valve is in fluid communication with the condenser fluid outlet and the fluid reservoir. The valve is operable to open and close to control flow of condensed fluid from the condenser to the fluid reservoir.
In another aspect, a method of removing a fluid from an ink jet printer includes providing an ink reservoir. A passive condenser is in fluid communication with the ink reservoir. Exhaust is received in the condenser from the ink reservoir and solvent is condensed from the exhaust. Air is vented from the condenser. Condensed fluid is removed from the condenser in an intermittent fashion.
The foregoing paragraphs have been provided by way of general introduction, and are not intended to limit the scope of the following claims. The presently preferred embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.
The invention is described with reference to the drawings in which like elements are referred to by like numerals. The relationship and functioning of the various elements of this invention are better understood by the following detailed description. However, the embodiments of this invention as described below are by way of example only, and the invention is not limited to the embodiments illustrated in the drawings.
The present disclosure relates to a condenser and condensate recovery system for use in an ink jet printer such as a continuous ink jet printer. The condenser provides a method of recovering and re-using solvent from the exhaust of an ink reservoir of an ink jet printer.
An embodiment of the condenser 40 is shown in
The condenser 40 may be fashioned from a bottom piece 80 and a cover piece 82, as shown in
Vent 66 is configured to allow gas (primarily air) to escape from the condenser 80, while preventing liquid from escaping. In one embodiment, best seen in
In normal use, the condenser 40 will only condense fluid at a relatively small rate relative to the condenser volume. Thus, the fluid only needs to be intermittently, rather than continuously, pumped. As shown in
A pump 52 is in fluid communication with the fluid outlet 68 to draw condensed fluid from the condenser 40 into the fluid reservoir 30 via line 56. In one embodiment, the pump 52 is the gutter pump of the ink jet printer. The gutter pump 52 normally returns fluid from the print head 54 to the ink reservoir 30. When valve 50 is open, however, gutter pump 52 also conveys condensed fluid from the condenser 40 to the ink reservoir 30. When valve 50 is open, gutter pump 52 may run at a higher rate than normal to maintain a constant flow rate from the print head 54.
As best seen in
In another embodiment, an alternative pump arrangement may be used. For example, the system may use a different or additional pump disposed in the fluid reservoir to draw fluid from the condenser to the ink reservoir 30. The pump used may be a venturi pump.
A second embodiment of a condenser assembly 100 is shown in
Turning to
As shown in
The condenser 140 may also include a chamber 160 disposed towards the bottom of the condenser 140. The chamber 160 provides a collection volume for condensed fluid and is in fluid communication with fluid outlet 148 and vent 146. The opening into vent 146 from chamber 160 is disposed at a top portion of chamber 160, above the opening into fluid outlet 148, so that condensed liquid flows into fluid outlet 148 and not into vent 146. Thus, fluid outlet 148 is preferably disposed at a bottom portion of the condenser 140 to permit removal of the condensed fluid.
As previously described, condenser 140 may be used in conjunction with the condenser assembly 100. Referring to
The various components of the condenser 40 and condenser assembly 100 may be made from any suitable conventional material. Condenser 140 is preferably made from a material with good thermal conductivity, such as aluminum.
When the condenser assembly 140 is used, the valve 50 may be opened more frequently than in the system using condenser 40. It is preferably used in an intermittent fashion. Thus, in one embodiment, the valve 50 operates in an open position for about 1 to 60 seconds every 10 minutes to convey condensed fluid from the condenser 40 back to the ink reservoir 30; at the other times, the valve is closed. In another embodiment, the valve operates in an open position for about 2 to 10 seconds, preferably about 5 seconds, every 10 minutes.
The described and illustrated embodiments are to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the scope of the inventions as defined in the claims are desired to be protected. It should be understood that while the use of words such as “preferable”, “preferably”, “preferred” or “more preferred” in the description suggest that a feature so described may be desirable, it may nevertheless not be necessary and embodiments lacking such a feature may be contemplated as within the scope of the invention as defined in the appended claims. In relation to the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used to preface a feature there is no intention to limit the claim to only one such feature unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.
| Number | Date | Country | Kind |
|---|---|---|---|
| 61/089279 | Aug 2008 | US | national |
This application claim priority to U.S. Provisional Application No. 61/089,279 filed Aug. 15, 2008, and incorporated herein by reference in its entirety
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US09/53838 | 8/14/2009 | WO | 00 | 2/3/2011 |
