Patent Application
20110115853
1. Field of the Invention
The present invention relates generally to a system and method for purging bubbles from a fluid ejection head and, more particularly to controlling the amount of ink ejected from the ejection head during a purging operation.
2. Description of the Related Art
Ink jet printers have a permanent fluid ejection head, which are not typically replaced by the customers. Rather, the supply item in this case that is replaced is the fluid cartridge mounted on the fluid ejection head. Air management in the fluid cartridge is an issue, since air can enter the fluid cartridge from several different sources resulting in blockage in the fluid ejection head that result in poor print quality if that air is not removed.
To purge bubbles, an air tight seal is provided around a plurality of fluid ejection nozzles of the fluid ejection head. The air tight seal has an opening at one end through which a negative pressure is exerted on the plurality of fluid ejection nozzles. The negative pressure removes ink and unwanted bubbles from the fluid ejection head. The fluidic resistance of the fluid ejection head determines the amount of ink removed during the purging operation. Some of the features that affect the fluidic resistance of ink are flow path length, area of the fluid ejection head, nozzle diameter, and fluid viscosity. Usually, there are significant differences in the flow features and fluid viscosity of monochrome ink compared to color ink.
Due to these differences, when the same pressure is applied to the monochrome ink and color ink during a purging operation, one of the color or monochrome ink is removed more than is needed.
Therefore, it would be advantageous to have a system that can control the amount of ink removed from the fluid ejection head during a purging operation.
Disclosed herein is a fluid ejection head including a plurality of fluid flow channels that includes a first plurality of fluid flow channels for flow of a first ink and a second plurality of fluid flow channels for flow of a second ink, the first ink being different from the second ink, a plurality of actuator devices including at least a first actuator device in thermal communication with the first plurality of fluid flow channels for heating the first ink, and at least a second actuator device in thermal communication with the second plurality of fluid flow channels for heating the second ink, a plurality of ink vias formed within the plurality of actuator devices, the plurality of ink vias in fluid communication with the first and second plurality of fluid flow channels, a nozzle plate attached to the plurality of actuator devices, the nozzle plate containing a plurality of fluid ejection nozzles corresponding to the plurality of ink vias, and a printer cap positioned adjacent the nozzle plate, the at least the first actuator device being pulsed with a first energy that depends on a viscosity of the first ink, the at least the second actuator device being pulsed with a second energy that depends on a viscosity of the second ink, the first energy being different from the second energy, a negative pressure being applied through the printer cap for purging bubbles from the first plurality of fluid flow channels, the second plurality of fluid flow channels, the plurality of ink vias, and the plurality of fluid ejection nozzles.
In some embodiments, pulsing the at least the first actuator device with the first energy and pulsing the at least the second actuator device with the second energy results in the viscosity of the first ink to be same as the viscosity of second ink.
In another aspect, a method for purging bubbles from a plurality of fluid flow channels and a plurality of ink vias of a fluid ejection head, the method includes pulsing the at least the first actuator device with a first energy, pulsing the at least the second actuator device with a second energy, and applying a negative pressure through the printer cap to purge bubbles from the first plurality of fluid flow channels, the second plurality of fluid flow channels, the plurality of ink vias, and the plurality of fluid ejection nozzles, the first energy being different from the second energy, the first energy and the second energy depending on the viscosity of the first ink and the second ink.
In yet another aspect, a method for purging bubble clogged in fluid ejection nozzles of a fluid ejection head, the method includes printing a pattern comprising a plurality of dots, each of the plurality of dots represents fluid ejection from the plurality of fluid ejection nozzles, scanning the pattern to determine missing one of the plurality of dots in the pattern, the missing one of the plurality of dots being indicative of a clog in one of the plurality of the fluid ejection nozzles, pulsing the actuator device associated with the clogged fluid ejection nozzle, and applying a negative pressure through the printer cap to purge the bubble from the clogged fluid ejection nozzle.
Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description, which follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description of the present embodiments of the invention are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operation of the invention.
The above-mentioned and other features and advantages of the various embodiments of the invention, and the manner of attaining them, will become more apparent will be better understood by reference to the accompanying drawings, wherein:
a-5b illustrate a plan view of one embodiment of a partial portion of the fluid ejection head showing fluid flow channels, fluid ejection nozzles, and actuator device for monochrome ink and color ink according to the present invention;
Reference will now be made in detail to the exemplary embodiment(s) of the invention, as illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts.
The fluid ejection head 12 also includes the plurality of actuator devices 22, formed on the substrate 20 attached to the fluid ejection head 12. The plurality of actuator devices 22 include a first actuator device 22a associated with the first plurality of fluid flow channels 32a and a second actuator device 22b associated with the second plurality of fluid flow channels 32b. The actuator devices 22 are preferably heater resistor devices.
A plurality of ink vias 34 are formed within the plurality of actuator devices 22. The plurality of ink vias 34 include a first plurality of ink vias 34a that are in fluid communication with the first plurality of fluid flow channels 32a, and a second plurality of ink vias 34b that are in fluid communication with the second plurality of fluid flow channels 32b.
The fluid ejection head 12 also includes a nozzle plate 16 attached to the substrate 20. The nozzle plate 16 includes the plurality of fluid ejection nozzles 18 formed within the nozzle plate 16. As shown, the fluid ejection nozzles 18a and 18b are associated with the ink vias 34a and 34b, respectively.
Air bubbles may be formed in the ink present in the plurality of fluid flow channels 32, the plurality of ink vias 34, and/or the plurality of fluid ejection nozzles 18. If these air bubbles are not removed, they may block or inhibit the flow of fluid from the fluid flow channels 32 to the ink vias 34, or from the ink vias 34 to the plurality of fluid ejection nozzles 18, causing poor print quality.
a-5b illustrate a plan view of one embodiment of a partial portion of the fluid ejection head 12 showing the plurality of fluid flow channels 32, the plurality of fluid ejection nozzles 18, and the plurality of actuator devices 22 for monochrome ink and color ink, respectively, according to the present invention. As a larger ink drop size of a monochrome ink is desired compared to the ink drop size of a color ink, the size of flow features, i.e., size of the fluid flow channel 32a, and the diameter of the fluid ejection nozzle 18a for a monochrome ink is comparatively larger than the size of flow features, i.e., size of the fluid flow channel 32b and the diameter of the fluid ejection nozzle 18b for a color ink. Further, the viscosity of color ink is different from the viscosity of monochrome ink.
Due to the difference in the flow features and the viscosity of color ink and monochrome ink, when the same negative pressure is applied for purging bubbles from the color ink and the monochrome ink, one of the inks is removed more than is needed to ensure that the bubbles is removed. The present invention alleviates the problem of removing excess ink by pulsing the actuator device 22a associated with the first plurality of fluid flow channels 32a with a first energy and pulsing the actuator device 22b associated with the second plurality of fluid flow channels 32b with a second energy that is different from the first energy. The first energy and the second energy are based on the viscosity of the first ink and the second ink, respectively, to ensure that the flow rates of different inks can be controlled independently, and more or less ink of a selected color can be removed during the purge operation while applying the same pressure over the same time span for all the inks.
At step S52 the second actuator device 22b that is in thermal communication with the second plurality of fluid flow channels 32b is pulsed with a second energy. The second energy heats the second ink flowing through the second plurality of fluid flow channels 32b. The second energy with which the second actuator device 22b is pulsed is determined based on the relationship between change in viscosity of the second ink with the change in temperature stored in the firmware. The second energy changes the viscosity of the second ink such that only a desired amount of second ink is purged out during the purging of bubbles present in the second plurality of fluid flow channels 32b, the plurality of ink vias 34b in fluid communication with the second plurality of fluid flow channels 32b, and the fluid ejection nozzles 18b in communication with the ink vias 34b.
Heating the first ink and the second ink with the first energy and the second energy that depend on the viscosity of the first ink and the second ink, results in the viscosity of the first ink to be same as the viscosity of the second ink. This ensures that an excess amount of either the first ink or the second ink is not purged out when same the negative pressure is applied through the printer cap 36 for purging bubbles present in the plurality of fluid flow channels 32, the plurality of ink vias 34 in fluid communication with the plurality of fluid flow channels 32, and the fluid ejection nozzles 18 in communication with the ink vias 34. Although, the method discussed here is only for two inks, purging bubbles from any number of inks having different viscosities by heating the inks based on their viscosity would fall within the scope of the invention.
The above described method of clog detection can also be utilized to determine a “deprime” situation, i.e., a situation when the plurality of fluid ejection nozzles 18 are filled only with air. This situation can arise, if the fluid cartridge 30 is not properly mounted on the fluid ejection head 12 or if there is a leak in the fluid ejection head 12 causing air to be filled in the fluid ejection nozzles 18. The deprime situation of the fluid ejection head 12 can be detected similar to the clog situation, by pulsing the plurality of actuator devices 22. If the plurality of fluid ejection nozzles 18 are filled with air heat would not be removed from the fluid ejection head 12 when negative pressure is applied through the printer cap 36, resulting in the temperature of the actuator devices 22 to be higher than the steady state temperature. This temperature information is then used to direct the customer to replace or repair the fluid ejection head 12.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
