Patent Application
20060158489
The following description relates to a printhead assembly including one or more nozzles.
An ink jet printer typically includes an ink path from an ink supply to an ink nozzle assembly that includes nozzles from which ink drops are ejected. Ink drop ejection can be controlled by pressurizing ink in the ink path with an actuator, which may be, for example, a piezoelectric deflector, a thermal bubble jet generator, or an electrostatically deflected element. A typical printhead has a line of nozzles with a corresponding array of ink paths and associated actuators, and drop ejection from each nozzle can be independently controlled. In a so-called “drop-on-demand” printhead, each actuator is fired to selectively eject a drop at a specific pixel location of an image, as the printhead and a printing media are moved relative to one another. In high performance printheads, the nozzles typically have a diameter of 50 microns or less (e.g., 25 microns), are separated at a pitch of 100-300 nozzles per inch and provide drop sizes of approximately 1 to 70 picoliters (pl) or less. Drop ejection frequency is typically 10 kHz or more.
A printhead can include a semiconductor printhead body and a piezoelectric actuator, for example, the printhead described in Hoisington et al., U.S. Pat. No. 5,265,315. The printhead body can be made of silicon, which is etched to define ink chambers. Nozzles can be defined by a separate nozzle plate that is attached to the silicon body. The piezoelectric actuator can have a layer of piezoelectric material that changes geometry, or bends, in response to an applied voltage. The bending of the piezoelectric layer pressurizes ink in a pumping chamber located along the ink path.
Printing accuracy can be influenced by a number of factors, including the uniformity in size and velocity of ink drops ejected by the nozzles in the printhead and among the multiple printheads in a printer. The drop size and drop velocity uniformity are in turn influenced by factors, such as the dimensional uniformity of the ink paths, acoustic interference effects, contamination in the ink flow paths, and the uniformity of the pressure pulse generated by the actuators. Contamination or debris in the ink flow can be reduced with the use of one or more filters in the ink flow path.
A printhead assembly including one or more nozzles is described. In general, in one aspect, the invention features a droplet ejection module. The droplet ejection module includes a liquid supply assembly, a housing and a droplet ejection body. The liquid supply assembly includes a self-contained liquid reservoir and a liquid outlet. The housing is configured to permanently connect to the liquid supply assembly and includes a liquid channel configured to receive a liquid from the liquid outlet of the liquid supply assembly and to deliver the liquid to a droplet ejection body. The droplet ejection body is permanently connected to the housing and includes one or more liquid inlets configured to receive liquid from the housing and one or more nozzles configured to selectively eject droplets.
Implementations of the invention can include one or more of the following features. The liquid supply assembly can further include a seal operable to prevent the liquid from exiting the liquid reservoir through the liquid outlet. The housing can be connected to the liquid supply assembly in a first position, where the seal prevents the liquid from exiting the liquid outlet and entering the liquid channel, and can be connected to the liquid supply assembly in a second position, where the seal does not prevent the liquid from exiting the liquid outlet and entering the liquid channel. The housing can be configured to connect to the liquid supply assembly in the first and second positions by a snap-fit connection.
The liquid supply assembly can further include a liquid supply housing, and a vacuum chamber can be formed within the liquid supply housing including a port for providing vacuum to the vacuum chamber. The liquid reservoir can be a flexible container adapted to contain a liquid, where the flexible container is positioned within the vacuum chamber in the liquid supply housing.
In general, in another aspect, the invention features a droplet ejection module including a housing, a droplet ejection body mounted to the housing, a flexible circuit, and a liquid supply assembly. The droplet ejection body has a nozzle face including at least one nozzle for ejecting a liquid and a back face having at least one liquid channel. The flexible circuit is attached to the housing and to the nozzle face of the droplet ejection body. The flexible circuit is electrically connected to the droplet ejection body to provide drive signals controlling liquid ejection from the at least one nozzle. The flexible circuit can be connected, directly or indirectly, to a processor or integrated circuit from which the drive signals originate. The liquid supply assembly is attached to the housing and in fluid communication with the back face of the droplet ejection body. The liquid supply assembly includes a self-contained liquid reservoir and an outlet providing a liquid path from the liquid supply assembly to the liquid channel formed in the back face of the printhead body.
Implementations can include one or more of the following. The droplet ejection module can further include one or more pumping chambers formed in a base substrate, where each pumping chamber includes a receiving end configured to receive a liquid from a liquid supply and an ejecting end for ejecting the liquid from the pumping chamber. A nozzle plate can be attached to the base substrate including one or more nozzles formed through the nozzle plate, where a nozzle is in fluid communication with each pumping chamber and receives liquid from the ejecting end of the pumping chamber for ejection from the nozzle. One or more piezoelectric actuators can be connected to the nozzle plate, where a piezoelectric actuator is positioned over each pumping chamber and includes a piezoelectric material configured to deflect and pressurize the pumping chamber, so as to eject liquid from a corresponding nozzle that is in fluid communication with the ejecting end of the pumping chamber.
The liquid supply assembly can include a liquid supply housing, a vacuum chamber formed within the liquid supply housing including a port for providing vacuum to the vacuum chamber, and a bag adapted to contain a liquid, the bag positioned within the vacuum chamber in the liquid supply housing.
The invention can be implemented to realize one or more of the following advantages. A printhead module that can be effectively used with a relatively small number of nozzles is provided that is ideal for uses involving small volumes of printing liquid. The self-contained printing liquid reservoir can be easily filled with a small volume of printing liquid, attached to a printhead housing and used for a printing operation. One implementation in which small printing liquid volumes is desirable is printing liquid test operations. The self-contained printing liquid reservoir can be filled with a test printing liquid and attached to the printhead housing to conduct a test operation. The entire assembly can be disposed of following the testing operation, avoiding having to flush clean a printhead module between tests. A one snap connection can be made to mount the printhead module into a mounting assembly, whereby an electrical connection and connection to a vacuum source are made simultaneously.
Details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages may be apparent from the description and drawings, and from the claims.
These and other aspects will now be described in detail with reference to the following drawings.
FIGS. 1A-E show a droplet ejection module including a self contained liquid supply assembly.
FIGS. 1F-H show enlarged views of a portion of a sealing mechanism included in the droplet ejection module of
FIGS. 2A-D show another embodiment of a droplet ejection module including a self contained liquid supply assembly.
FIGS. 3A-B show a droplet ejection body including 10 nozzles.
FIGS. 4A-B show an alternative droplet ejection body including 10 nozzles.
FIGS. 5A-C show a flexible circuit attached to a droplet ejection body and to a housing.
FIGS. 7A-E show an alternative embodiment of a droplet ejection module including a self contained liquid supply assembly.
Like reference symbols in the various drawings indicate like elements.
A droplet ejection module is described that includes pressurized pumping chambers to selectively eject a liquid from nozzles. A typical liquid is ink, and for illustrative purposes, the droplet ejection module is described below in reference to a printhead module that uses ink as the printing liquid. However, it should be understood that other liquids can be used, for example, electroluminescent material used in the manufacture of liquid crystal displays or liquid metals used in circuit board fabrication.
A printhead module generally includes a printhead body with multiple nozzles that are in fluid communication with an external ink supply to allow for a continuous printing operation. In certain applications, a printhead module that can be effectively operated using a relatively small volume of ink, e.g., for an ink testing operation, is desirable. A printhead module configured to house a printhead body with a relatively small number of nozzles, e.g., from one to ten nozzles, is suitable for such an operation, and includes an ink supply assembly designed for a relatively small volume of printing liquid. In one embodiment, a non-refillable ink supply assembly can be attachable to a printhead body, e.g., a single-use printing liquid supply cartridge, thereby avoiding having to flush clean an ink supply assembly when testing different printing liquids.
Referring particularly to
Referring particularly to
To connect the ink supply assembly 102 to the printhead housing 104 in the closed position A, a user aligns the male connectors 115 protruding from the ink supply assembly 102 with the corresponding female connectors 117 formed in the printhead housing 104 and exerts enough force to engage the male connectors 115 with the female connectors 117 at position A, but not too much force so as to engage the female connectors 117 at position B. The user should receive enough tactile feedback when mating the ink supply assembly 102 to the printhead housing 104 to determine when position A has been reached.
To move the ink supply assembly 102 into the open position B with respect to the printhead housing 104, a user exerts additional force to engage the male connectors 115 with the female connectors 117 at position B. The male connectors 115 have enough flexibility to bend under pressure to disengage from the female connectors 117 at position A and snap into engagement at position B. The female connectors 117 can be configured to facilitate this movement, for example, by having angled faces as depicted that encourage the similarly angled male connectors 115 to slide out of engagement upon the exertion from a downward force. The above describes one implementation of a double snap-fit connection. Other configurations of a double snap-fit connection can be used, as well as other types of connections that allow for a closed and an open position.
The fluid path formed between the ink supply assembly 102 and the printhead body 106 can be better understood by further explaining the configuration of the ink inlet 124, shown in closer detail in
Referring to
The ink supply assembly 102 includes a vacuum chamber 128 housing the ink bag 108. A vacuum is maintained in the vacuum chamber 128 by a valve 130 that can be connected to a vacuum source. Maintaining a vacuum in the vacuum chamber 128 applies a negative pressure to the ink bag 108, relative to atmospheric pressure outside the nozzles, that can create a pressure at the meniscus at the nozzles openings, so that the ink does not leak from the nozzles. At the same time, the pressure at the meniscus is such that air is not drawn back into the pumping chamber.
In one embodiment, attaching the ink supply assembly 102 to the printhead housing 104 can be permanent and once the ink contained within the ink bag 108 has been used, the printhead module 100 can be discarded. The ink bag 108 is filled via the outlet head 118 before attaching the ink supply assembly 102 to the printhead housing 104. The printhead module 100 thereby provides a self-contained disposable testing unit that uses only a small volume of test liquid. Because the printhead module 100 is only used once, testing can occur without flushing clean printhead modules between tests.
Referring to FIGS. 2A-D, a second embodiment of a printhead module 200 that can be used with a printhead body having a relatively small number of nozzles is shown. Referring particularly to
Preferably the ink bag 208 is filled before the ink supply assembly 202 is attached to the printhead housing 204. Referring particularly to
Referring particularly to
The ink supply assembly 202 includes a vacuum chamber 220 housing the ink bag 208. A vacuum is maintained in the vacuum chamber 220 by a valve 230 that can be attached to a vacuum source. Maintaining a vacuum in the vacuum chamber 220 applies a negative pressure to the ink bag 208, relative to the atmospheric outside the nozzles, that can create a pressure at the meniscus at the nozzle openings so that the ink does not leak from the nozzles. At the same time, the pressure at the meniscus is such that air is not drawn back into the pumping chamber.
As described above in reference to the embodiment depicted in FIGS. 1A-H, attaching the ink supply assembly 202 to the printhead housing 204 can be permanent and once the ink contained within the ink bag 208 has been used, the printhead module 200 can be discarded. The printhead module 200 thereby provides a self-contained disposable unit that uses only a small volume of liquid, e.g., a test liquid. Because the printhead module 200 is only used once, testing can occur without flushing clean printhead modules between tests. Alternatively, the ink bag 208 can be refilled via the port 209 for subsequent printing operations, however, because the ink bag 208 cannot easily be cleaned, this is not recommended unless refilling with the same ink.
In an alternative embodiment, the port 209 can be eliminated. The septum 217 can be formed from a self-sealing material and ink can be injected into the ink bag 208 via the septum 217 before the ink supply assembly 202 is attached to the printhead housing 204. Alternatively, ink can be injected into the ink bag 208 before the septum 217 is attached; once the ink bag 208 is filled the septum 217 can be attached to seal the ink bag 208, which can then be attached to the printhead housing 204.
The printhead modules 100 and 200 described above can be used with any suitable printhead body. One embodiment of a printhead body 300 that includes 10 nozzles is shown in
Referring again to
The exemplary printhead body 300 shown includes 10 nozzles, however, more or fewer nozzles can be included. In one embodiment, the printhead body 300 includes a single nozzle. The printhead body 300 can be fabricated using techniques described in U.S. patent application Ser. No. 10/962,378, entitled “Print Head With Thin Membrane”, filed Oct. 8, 2004, and/or techniques described in U.S. Provisional Patent Application No. 60/621,507 entitled “Sacrificial Substrate for Etching”, filed Oct. 21, 2004, the entire contents of which applications are hereby incorporated by reference herein.
Another embodiment of a printhead body 400 is shown in
The exemplary printhead body 402 shown includes 10 nozzles, however, the printhead body 402 can be formed with more or fewer nozzles. In one embodiment the printhead body 402 includes a single nozzle.
The printhead module further includes a contact face for electrically connecting to a source providing signals to selectively activate the nozzles and can be configured to mount within a printing device to eject the printing liquid contained therein onto a substrate. The configuration of the contact face can differ depending on the configuration of the printhead body.
For example,
The flexible circuit 500 is configured to wrap around a side of a printhead housing 508 as shown in
In another implementation, the printhead module can be configured to mount with a cartridge mount assembly as described in Appendix A entitled “Fluid Deposition Device”, which is hereby incorporated into this Specification.
In one embodiment, the printhead module and a mounting structure can be configured so that in a single connection step, an electrical connection is made to the printhead module and a connection is made from a vacuum source to the vacuum port. For example, if the printhead module is positioned into the mounting structure, then with one positioning step, the contacts on the contact face of the printhead module can electrically connect, e.g., to an external flexible circuit and/or to an external device (e.g., to send signals to actuate the nozzles), and the vacuum port can connect to a vacuum source, e.g., the meniscus vacuum bar 606. The external flexible circuit can be connected to a processor or integrated circuit from which drive signals to the nozzles originate.
Another embodiment of a contact face for a printhead module can be described in reference to FIGS. 1A and 4A-B that can be used when the printhead body is configured with drive contacts on the same face as the nozzles. Referring particularly to
The flexible circuit 160 can be formed similar to the flexible circuit 500 described above, in that the flexible circuit 160 can include leads that connect to the drive contacts 420 to provide signals to selectively activate the corresponding nozzles 412. The flexible circuit 160 includes a contact face 164 having contacts 166 to electrically connect to an external circuit providing the drive signals for the nozzles. For example, referring again to
Referring to FIGS. 7A-E, an alternative embodiment of the printhead module 700 is shown. This embodiment is substantially similar to the printhead module 100 shown in
The ink path from the self-contained ink reservoir (ink bag) 708 to the printhead body 706 is similar to the ink path described in reference to the printhead module 100 depicted in FIGS. 1A-H. That is, the ink column 702 includes fingers 732 and grooves 734. The ink supply assembly 703 includes an outlet head 718 also having fingers 736 radiating from a central hub 739 and separated by flow paths 738. The flow paths 738 provide an ink path from the ink bag 708. In a closed position, a seal 710 is in contact with the bottom surface of the outlet head 718 and blocks the flow paths 738; ink cannot flow past the fingers 736. A spring 714 in the outlet head 718 exerts a downward force compressing the seal 710.
In an open position, the bottom of the outlet head 718 contacts the ink inlet 724, which can compress the spring 714 within the outlet head 718. The seal 710 is positioned past the distal end of the ink inlet 724 and is not in contact with the bottom of the outlet head 718; the flow paths 738 are no longer blocked by the seal 710. Ink can thereby flow from the ink bag 708 through the flow paths 738 formed between the fingers 736 of the outlet head 718 and into the ink channel 726 formed in the ink inlet 724 through the grooves 734 formed therein.
Referring particularly to
The printhead module 700 can also be mounted into a mounting assembly as shown in
As previously mentioned, ink is just one example of a printing liquid. It should be understood that references to ink as the printing liquid were for illustrative purposes only, and referring to components within the printhead module described above with the adjective “ink” was also illustrative. That is, referring to a channel or a supply assembly as an “ink inlet” or an “ink supply assembly” was for illustrative purposes, and a more general reference, such as to a “printing liquid inlet” or a “printing liquid supply assembly” can be used. Further, as previously mentioned, the drop ejection module has been referred to for illustrative purposes as a printhead module, however, the use can be broader than printing operations per se, and can be used to eject drops of any sort of liquid for various purposes.
The use of terminology such as “front” and “back” and “top” and “bottom” throughout the specification and claims is for illustrative purposes only, to distinguish between various components of the printhead module and other elements described herein. The use of “front” and “back” and “top” and “bottom” does not imply a particular orientation of the printhead module.
Although only a few embodiments have been described in detail above, other modifications are possible. Other embodiments may be within the scope of the following claims.
This application claims priority to pending U.S. Provisional Application Ser. No. 60/637,254, entitled “Single-Use Droplet Ejection Module”, filed on Dec. 17, 2004, the entire contents of which are hereby incorporated by reference, and claims priority to pending U.S. Provisional Application Ser. No. 60/699,134, entitled “Single-Use Droplet Ejection Module”, filed on Jul. 13, 2005, the entire contents of which are hereby incorporated by reference. This application is related to concurrently filed U.S. application entitled “Printhead Module”, filed on ______, 2005, and assigned U.S. Ser. No. ______, by Andreas Bibl and Melvin L. Biggs.
| Number | Date | Country | |
|---|---|---|---|
| 60637254 | Dec 2004 | US | |
| 60699134 | Jul 2005 | US |
