Gaseous detection for an inkjet system

A method of monitoring gaseous accumulation within an ink flow path in fluid communication with a printhead comprising: (a) supplying a first printhead with ink using a first ink flow path; (b) mounting a first ink filter in fluid communication with the first printhead; and (c) sensing downstream from the first ink filter for gaseous components within the first ink flow path. In addition, the invention provides a printing device comprising: (a) a first printhead that includes a first set of nozzles, a first ink filter, and a first conduit between the first ink filter and the first set of nozzles for delivering filtered ink to the first set of nozzles; and (b) a sensor operative to detect at least one of bubble formation and bubble growth within the first conduit.

BACKGROUND

1. Field of the Invention

The present invention is directed to inkjet printers, and more specifically to devices and methods for detecting the presence of gaseous impediments within ink conduits that might impair the flow of ink between an ink source and nozzles of a printhead.

2. Background of the Invention

Inkjet printers include at least one printhead having numerous nozzles through which ink is ejected in the form of droplets that are preferably deposited onto a printable medium. The precise and accurate deposition of droplets form image-based, dielectric, and/or conductive representations. In order to deposit ink onto the printable medium, the printhead includes numerous electric resistors that are selectively “fired”. A resistor is “fired” by directing electric current therethrough to generate thermal energy sufficient to vaporize a fraction of liquid ink in thermal communication with the resistor, thereby generating a vapor bubble that forces a droplet of liquid ink from the nozzle. The resistor firing sequence occurs numerous times a second and is coordinated with the movement of the nozzles across the printable medium by associated controls of the printer.

An electronic version of the representation to be printed is commonly referred to as a bit map. A bit map includes instructions regarding the position of the nozzles in order to deposit ink in predetermined locations on the print medium. This means that at least one of the nozzles and the print medium must be repositionable. An exemplary manner of repositioning the print medium with respect to the nozzles may include moving the print medium vertically and moving the nozzles horizontally along a reel to cover the relevant areas of an imaginary X-Y plane. The operation of a reel and movement of the printhead in accordance with the instructions of the bit map are well known by those of ordinary skill.

SUMMARY OF THE INVENTION

The present invention includes devices and methods for detecting the presence of gaseous deposits within conduits located between an ink source and nozzles of a printhead. As will be discussed in more detail below, the present invention may utilize an optical sensor for detecting the presence of gaseous impediments, which may include ink vapor bubbles, downstream from an ink filter. The sensor may be operative to generate and send signals indicative of ink flow impairment to the printer controller, and the printer controller, upon receipt of these signals, may discontinue printing if the impairment of ink flow is significant and/or would lead to printhead damage if printing was continued without correcting the impairment. Exemplary embodiments include mounting the sensor to a printhead, where the printhead includes a translucent lens operative to allow optical communication between a downstream portion of the ink conduit and the sensor. In a detailed exemplary embodiment, the invention may include the sensor interfacing with electronic controls of the printer to alert a user that the flow of ink to the printhead is blocked or impaired and notify the user that further printing operations may cause damage the printhead. In a further detailed exemplary embodiment, the alert may include instructions to the user for manually purging the gaseous deposits from the ink conduit. In a yet a further detailed exemplary embodiment, the alert may include the electronic controls activating an automated purging sequence to eliminate the gaseous impediments. It is to be understood that the gaseous impediments may result from consumption of the ink in fluid communication with the printhead, in which case ink replenishment may be required.

In accordance with an embodiment of the present invention, a method is provided for monitoring gaseous accumulation within an ink flow path in fluid communication with a printhead. As described herein, the method can include the steps of (a) supplying a first printhead with ink using a first ink flow path; (b) mounting a first ink filter in fluid communication with the first printhead; and (c) sensing downstream from the first ink filter for gaseous components within the first ink flow path.

In another embodiment, the downstream sensing within the first ink flow path uses an optical sensor. In another more detailed embodiment, the optical sensor is a component of at least one of a removable ink tank and the first printhead. In a further detailed embodiment, the first printhead traverses across a reel of a printer, and the optical sensor is stationary with respect to the first printhead. In still a further detailed embodiment, the first printhead traverses across a reel of a printer, and the optical sensor is stationary with respect to the printer. In a more detailed embodiment, the method also includes generating a signal in response to sensing gaseous components downstream from the first ink filter, and automatically redirecting at least some of the gaseous components in response to the signal generation. In a more detailed embodiment, the method also includes supplying a second printhead with ink using a second ink flow path, mounting a second ink filter in fluid communication with the second printhead, sensing downstream from the second ink filter for gaseous components within the second ink flow path, supplying a third printhead with ink using a third ink flow path, mounting a third ink filter in fluid communication with the third printhead, and sensing downstream from the third ink filter for gaseous components within the third ink flow path.

In still another embodiment, the first printhead, the second printhead, and the third printhead traverses across a reel of a printer, and supplying the first printhead, the second printhead, and the third printhead with ink includes providing at least one removable reservoir in fluid communication therewith. In still another more detailed embodiment, the downstream sensing within the first ink flow path, the second ink flow path, the third ink flow path includes utilizing an optical sensor, and the optical sensor is stationary with respect to the printer. In a further detailed embodiment, the downstream sensing within the first ink flow path, the second ink flow path, and the third ink flow path includes utilizing a plurality of optical sensors, and at least one of the plurality of optical sensors is stationary with respect to the printer. In still a further detailed embodiment, the method also includes generating a signal in response to sensing gaseous components downstream from at least one of the first ink filter, the second ink filter, or the third ink filter, and signaling a user of the printer that gaseous components have been detected downstream from at least one of the first ink filter, the second ink filter, or the third ink filter and providing instructions for redirecting at least some of the gaseous components. In a more detailed embodiment, the method also includes generating a signal in response to sensing gaseous components downstream from at least one of the first ink filter, the second ink filter, or the third ink filter, and automatically redirecting at least some of the gaseous components in response to the signal generation.

In accordance with another embodiment of the present invention, a printing device is described that includes: (a) a first printhead comprising: (i) a first set of nozzles, (ii) a first ink filter, and (iii) a first conduit between the first ink filter and the first set of nozzles for delivering filtered ink to the first set of nozzles; and (b) a sensor operative to detect at least one of bubble formation and bubble growth within the first conduit.

In another embodiment, the first conduit includes a first bubble accumulation area, and the sensor is in sensing communication with the first bubble accumulation area. In still another more detailed embodiment, the ink filter is mounted to the conduit at an angle to direct bubbles within the filtered ink to the bubble accumulation area. In a further detailed embodiment, the sensor includes an optical sensor. In still a further detailed embodiment, the printhead is disposable, and the sensor is integrated into the printhead. In a more detailed embodiment, the printhead is disposable, and the sensor is a standalone item.

In accordance with another embodiment of the present invention, an inkjet printer is provided that includes: (a) a first printhead comprising: (i) a first set of nozzles, (ii) a first ink filter, (iii) a first ink reservoir in fluid communication with the first ink filter, and (iv) a first conduit between the first ink filter and the first set of nozzles for delivering filtered ink to the first set of nozzles; (b) a reel adapted to traverse the first printhead across a width of a print medium; (c) a sensor operative to detect at least one of bubble formation and bubble growth within the first conduit; and (d) electronic controls for automatically directing the first printhead into position and controlling firing of the first set of nozzles.

DETAILED DESCRIPTION

The exemplary embodiments of the present invention are described and illustrated below to encompass devices and methods for detecting the presence of gaseous impediments within conduits located between an ink source and nozzles of a printhead. Of course, it will be apparent to those of ordinary skill in the art that the preferred embodiments discussed below are exemplary in nature and may be reconfigured without departing from the scope and spirit of the present invention. However, for clarity and precision, the exemplary embodiments discussed below may include optional features that one of ordinary skill will recognize as not being a requisite to fall within the scope of the present invention.

ReferencingFIG. 1, a first exemplary embodiment of the present invention includes a printer8having a reel10along which a carriage11, having a printhead12mounted thereto, traverses. A drive mechanism (not shown), controlled by a printer controller14, is operative to reposition the carriage11and printhead12along the reel10. The printhead12may include one or more banks of nozzles16providing orifices through which ink in fluid communication therewith is selectively deposited onto a print medium18per the instructions received from the printer controller14. Several options are available to provide on-demand ink in fluid communication with the nozzles16. Among these options include providing one or more ink cartridges (on-carrier chiclets)20mounted to the printhead12, as well as providing one or more ink reservoirs (not shown) in an off-carrier arrangement that are in fluid communication with the printhead12. For purposes of illustration, the printhead12is presumed to be fluidicly coupled to one or more on-carrier ink cartridges20, however, those of ordinary skill will understand that the distinction between on-carrier and off-carrier ink supplies in no way limits the applicability of the present invention only to on-carrier ink supplies.

ReferencingFIGS. 2 and 3, the exemplary printhead12includes an outer housing22surrounding three trapezoidally raised bays24,26,28that are each adapted to fluidicly interface with an ink cartridge20(SeeFIG. 1). Each bay24,26,28includes a raised wall30having an ink filter32(not shown inFIG. 2) mounted thereto. It is to be understood that the ink filter32may comprise a single piece of filter material or may comprise multiple pieces of filter material mounted to each bay24,26,28. In either instance, the orientation of the filter32is angled as a result of the angled nature of the bays24,26,28. During normal operation of the printhead12, the filter32is adapted to be in concurrent fluid communication with ink being directed to the printhead12and ink traveling from an interior of the ink cartridge20.

Each trapezoidally raised bay24,26,28defines a fluidicly separate fluid flow path that is adapted to receive a different ink such as, without limitation, cyan colored ink, magenta colored ink, and yellow colored ink. It is to be understood that this exemplary embodiment may be easily reconfigured to accommodate more or less than three colored inks. Still further, it is to be understood that the three separate bays24,26,28may receive the same colored ink. Even further, it is to be understood that each bay24,26,28may receive conductive or dielectric based inks for printing microcircuits.

After the ink travels through the respective filter32of each bay24,26,28, the ink is directed to one or more nozzles16on the underside of the printhead12. In this exemplary embodiment, the printhead12includes three sets of nozzles16, with each set of nozzles being in fluid communication with one of the bays24,26,28. However, it is to be understood that the bays24,26,28may all be in fluid communication with the same set of nozzles16or each bay24,26,28may be in fluid communication with more than one set of nozzles16. Those of ordinary skill are familiar with such configurations.

Referring toFIG. 3, each trapeziodally raised bay24,26,28includes a vapor collection zone34partially bounded by the underside of the filter32. Vapor present below the filter32is directed upward to the highest possible point as a result of buoyancy. In instances where a volume of vapor (bubbles) below the ink filter32is too large to pass through the filter32, the vapor accumulates at the vapor collection zone34on the underneath side of the filter32. It is to be understood that the trapped vapor may act to inhibit the flow if liquid ink through the filter32as the vapor occupies a portion of the available openings through the filter32.

ReferencingFIGS. 4-6, it can be seen that an angled filter32(FIG. 5) provides more surface area available for ink flow therethrough than a horizontal filter32′ (FIG. 4) for a comparable width and length opening within an ink flow path. As shown inFIG. 4, if the filter32′ is positioned horizontally or has a slight angle, vapor trapped beneath the filter32′ remains in one location and can more easily block the flow of liquid ink through the filter32′. The angled nature of the filter32ofFIG. 5shows that not only does the filter32provide more cross sectional area for ink to flow therethrough, but that the angled nature of the filter32directs the vapor horizontally as the buoyant nature of the vapor moves it vertically toward the vapor collection zone34. In this manner, it is easy to see that the angled filter32ofFIG. 5may be advantageous over a horizontally positioned filter32′ ofFIG. 4.FIG. 6shows a vertical filter (shown with dashed lines) where the dominant vertical nature of the filter provides little, if any, impediment to upward movement of the vapor, thereby resulting in diminished opportunity for the vapor to block an appreciable area of the filter32″ from ink flow therethrough.

Referring toFIGS. 2 and 3, three sensors36(not shown inFIG. 2) are mounted to the printhead12to detect vapor within the vapor accumulation zone34of each bay24,26,28. A lens37mounted adjacent to each bay24,26,28provides a translucent path between a respective vapor accumulation zone34and a respective sensor36, thereby allowing the sensor36to detect the level of vapor accumulation underneath each filter32and communicate the degree of vapor detected to the printer controller14. In this manner, the printer controller14is provided with real-time information regarding the degree of vapor accumulated underneath each filter32. An exemplary material for use as a lens37includes polypropylene having the appropriate haze and transmission properties allowing light to pass therethrough.

The printer controller14is programmed to determine whether signals received from each sensor36are indicative of conditions that might be harmful to the printhead12, such as, without limitation, nozzle16starvation and dry firing. If the controller14determines that one or more signals are indicative of an accumulation of vapor surpassing a predetermined threshold, the controller14may stop the printing sequence. Other possible exemplary responses of the controller14to surpassing the predetermined vapor accumulation threshold may include sending a signal to an automatic purging device38associated with the printhead12, such as, without limitation, a purge pump38to create a pressure differential and redirect the vapor from underneath the filter32. An exemplary purging technique includes providing a sealed perimeter exterior to and around the nozzles16to provide a low pressure area (commonly referred to as providing a vacuum) drawing ink from within the printhead to displace the accumulated vapor. An alternate exemplary technique includes providing a port (not shown) in direct communication with the accumulation area34and creating a low pressure area drawing the vapor from the accumulation area and through the port, such as by pumping. Still further exemplary responses by the printer controller14to significant vapor accumulation include prompting a user of the printer8to manually purge the vapor accumulated underneath the filter32and/or to replace/refill the ink reservoir20in fluid communication with the nozzles16.

It is also within the scope of the present invention to prime the printhead12using positive pressure in response to the controller14determining that a signal from one sensor36is indicative of a level of vapor surpassing a predetermined vapor accumulation threshold. Those of ordinary skill are familiar with off-carrier ink delivery systems that provide positive pressure ink flow between an off-carrier ink reservoir and an on-carrier printhead using a pump. The positive pressure supplied by the pump is commonly discontinued subsequent to establishing liquid communication between the ink and filter tower. However, the pump may also be utilized to force ink through the tower and displace the vapor accumulated beneath the filter32.

Referring toFIG. 7, a second exemplary embodiment includes a printer50having a reel52along which a printhead54traverses. A drive mechanism (not shown), controlled by a printer controller56, is operative to reposition the printhead54along the reel52. The printhead54may include one or more banks of nozzles58adapted to provide orifices through which ink in fluid communication therewith is selectively deposited onto a print medium per the instructions received from the printer controller56. To provide on-demand ink in fluid communication with the nozzles58, the printhead54may be integrated with one or more ink reservoirs (printhead cartridges), may be fluidicly coupled to one or more on-carrier ink cartridges, or may be in fluid communication with one or more off-carrier ink supplies. In this exemplary embodiment, the printhead54includes three bays60,62,64each in fluid communication with an ink supply.

The printer50also includes a stationary bank of sensors66,66′,66″ (i.e., one sensor for each bay60,62,64). Each sensor is communicatively connected to the printer controller56and operative to generate signals representative of the degree of vapor accumulation downstream from an ink filter (not shown) within a bay60,62,64. In this manner, the printer controller56may provide an exemplary response, as discussed in the first exemplary embodiment, when one or more of the bays60,62,64includes an accumulation of vapor that might be problematic to printhead54longevity. It is to be further understood that by using a separate sensor66,66′,66″ for each bay60,62,64, the response may be bay-specific.

ReferencingFIG. 8, an exemplary flow diagram for use with the second exemplary embodiment may arbitrarily start at step70with the continued printing of the printer50. The printer controller56is concurrently operative at step70to control the printing functions of the printhead54and to monitor the number and/or frequency of nozzle firings. At step72, the printer controller56is operative to reposition the printhead54to a sensing position where each sensor66,66′,66″ is positioned to detect the degree of vapor accumulation downstream from an ink filter (not shown) within each bay60,62,64. The instruction to reposition the printhead54to the sensing position may be carried out as a standby protocol, as a start-up protocol, as a continued printing protocol, or other protocol. At step74, each senor66,66′,66″ detects the degree of vapor accumulation downstream from the ink filter within a corresponding bay60,62,64. The printer controller56at step76determines whether the sensor signals are indicative of vapor accumulation levels below a predetermined threshold. The predetermined threshold may take into account may factors within the purview of one of ordinary skill. If the printer controller56determines that the vapor downstream from the ink filter is not at or above the threshold value, the printing operations of the printer50are resumed or declared ready for service pending receipt of one or more print jobs. If the printer controller56determines that the vapor downstream from the ink filter is at or above the threshold value, one or more countermeasures may be initiated and carried out in step78.

Exemplary countermeasures include notifying a user of the printer50that one or more ink cartridges need to be replaced. Further exemplary countermeasures include automatically initiating a purging or priming sequence using a pump, whether the pump creates a high pressure source upstream from the vapor accumulation area or a low pressure source downstream from the vapor accumulation area. It is to be understood that the countermeasures of the present invention encompass any response that provides at least one of vapor depletion/displacement or inhibits printing until such depletion/displacement occurs.

Subsequent to one or more of the countermeasures being carried out in step78, the printer controller56is operative initiate step72and reposition the printhead54to the sensing position so that the degree of vapor accumulation downstream from each ink filter may be determined. It is to be understood that one or more of the countermeasures may take place while the printhead is already positioned at a sensing position and, thus, step72would be skipped and the printer controller would simply poll the sensors66,66′,66″ at step74to determine whether additional countermeasures are necessary. It is also to be understood that after the countermeasures are carried out, printing may be continued without requiring the execution of steps72-76.

ReferencingFIG. 7, it is also within the scope of the invention to provide a single stationary sensor66that detects the degree of vapor accumulation downstream from the ink filter within each bay60,62,64. In such an exemplary embodiment, a timer69may be associated with the printer controller56to incrementally reposition the printhead54along the reel52such that the sensor66would be aligned with a detection point associated with one of the bays60,62,64and operative to detect the vapor accumulation within one bay in sequence. An exemplary detection point includes a translucent window (not shown) associated with each bay60,62,64enabling detection of the vapor accumulation downstream from the ink filter within each bay60,62,64.

ReferencingFIG. 9, a third exemplary embodiment includes a printer90having a reel92along which a printhead94traverses. A drive mechanism (not shown), controlled by a printer controller96, is operative to reposition the printhead94along the reel92. The printhead94may include one or more banks of nozzles98adapted to provide orifices through which ink in fluid communication therewith is selectively deposited onto a print medium per the instructions received from the printer controller96. To provide on-demand ink in fluid communication with the nozzles98, the printhead94may be integrated with one or more ink reservoirs (printhead cartridges), may be fluidicly coupled to one or more on-carrier ink cartridges, or may be in fluid communication with one or more off-carrier ink supplies. Those of ordinary skill are familiar with such alternatives. In this exemplary embodiment, the printhead94includes three bays each in fluid communication with a separate on-carrier cartridge100,102,104.

The printer90also includes a bank of sensors106A,106B,106C that are remotely mounted from the printhead74. In this exemplary embodiment, the sensors106A,106B,106C are mounted to a platform108of the printer90that is repositionable with respect to the printer and with respect to the printhead94. Each sensor106A,106B,106C is communicatively connected to the printer controller96and is operative to relay signals to the printer controller96that are representative of the amount of accumulated vapor below the filter in fluid communication with each cartridge100,102,104.

In practice, the repositionable platform108receives instructions from the printer controller96that correspond to and approximately match the side-to-side movement of the printhead94so that the sensors106A,106B,106C can monitor the accumulation of vapor downstream from the ink filter as the printhead94traverses across the printable medium. Using the signals generated by the sensors106A,106B,106C, the printer controller96determines whether the accumulation of vapor downstream from the ink filter may be problematic to printhead94longevity. If the level of vapor downstream from the ink filter is beyond a predetermined threshold value, the printer controller96may activate countermeasures adapted to reduce the level of vapor and/or inhibit further printing until the level of vapor drops or is eliminated. These countermeasures may include notifying a user of the printer that a cartridge100,102,104needs to be replaced, or automatically initiating a purging sequence using a purge pump110to decrease the degree of vapor accumulation. It is to be understood that the countermeasures include any response that provides at least one of vapor depletion/displacement, inhibits printing until such depletion/displacement occurs, or provides instructions or notification to alleviate the current problem.

It is to be further understood that by using a separate sensor106A,106B,106C corresponding to the flow of ink attributable to a cartridge100,102,104, the countermeasures may be specific to conditions of a particular cartridge. In an exemplary instance, the printer controller96may initiate an automated purging sequence using the purge pump110to purge ink from only one of the cartridges. Alternatively, or in addition, the controller96may alert a user that printing operations should be suspended and prompting for a manual purge or other remedy that may be cartridge specific.

Exemplary sensors for use with the present invention include, without limitation, light emitting sources such as light emitting diodes (LEDs), infrared emitting diodes (IRDs), and photodiodes, coupled with a light receiver/detector such as a phototransistor. It is to be understood that while the exemplary sensors discussed above have been optical in nature, those of ordinary skill will understand that other sensors, such as pressure sensors, may be used in lieu of optical sensors or in addition to optical sensors to detect the accumulation of vapor downstream from an ink filter.

Following from the above description and invention summaries, it should be apparent to those of ordinary skill in the art that, while the methods and apparatuses herein described constitute exemplary embodiments of the present invention, the invention contained herein is not limited to this precise embodiment and that changes may be made to such embodiments without departing from the scope of the invention as defined by the claims. Additionally, it is to be understood that the invention is defined by the claims and it is not intended that any limitations or elements describing the exemplary embodiments set forth herein are to be incorporated into the interpretation of any claim element unless such limitation or element is explicitly stated. Likewise, it is to be understood that it is not necessary to meet any or all of the identified advantages or objects of the invention disclosed herein in order to fall within the scope of any claims, since the invention is defined by the claims and since inherent and/or unforeseen advantages of the present invention may exist even though they may not have been explicitly discussed herein.