Ink Jet Method and Apparatus

This invention relates to a method and apparatus for jetting ink, and more particularly to a method and apparatus by which ink is supplied from a reservoir to one or more ink jets.

Ink jet apparatus typically employ an ink jet chamber having an orifice for ejecting droplets of ink which is supplied by an ink handling system. Ink handling systems frequently include bubble trap chambers which are adapted to prevent bubbles of air from reaching the ink jet chamber and clogging the relatively small passages leading to the chamber or causing compliance so as to reduce the effect of the "jetting" pressure pulse which would thereby interfere with the proper operation of the ink jet. Ink handling systems may also include level sensors for sensing the amount of ink in an ink supply or reservoir associated with the system. Both bubble trap chambers and level sensing typically require a particular orientation to function properly. In other words, if an ink jet apparatus employs the bubble trap chamber and/or a level sensor is inclined or inverted, the bubble trap chamber and/or the level sensing mechanism may not function properly. Ink handling systems also typically assure a predetermined and proper hydrostatic head at the ink jet chamber.

It will therefore be appreciated that it is particularly important that the ink path immediately preceding the ink jet chamber have predetermined characteristics. It is not therefore possible to simply couple an ink jet chamber to a remote ink handling system by means, for example, of a tubular connection and still achieve reliable and high performance operation of the ink jet.

It is an object of this invention to provide an ink jet apparatus and method of assembling an apparatus which may be utilized regardless of the orientation of the ink jet.

It is a more specific object of the invention to provide an ink jet apparatus and method of assembling an apparatus wherein the bubble trap chamber associated with the apparatus will function properly regardless of the orientation of the ink jet.

It is another specific object of this invention to provide and ink jet appartus and method of assembling an ink jet apparatus which has an ink level sensor which will function properly regardless of the orientation of the ink jet.

It is a further object of this invention to provide such an apparatus and such a method in a reliable manner.

It is a still further object of this invention to provide such an apparatus and such a method in a relatively low-cost manner.

It is a still further object of this invention to provide an ink jet apparatus and method of assembling such an apparatus which is capable of high performance regardless of the orientation of the ink jet.

In accordance with these and other objects of the invention, a first ink handling module includes an ink supply path adapted to communicate with a reservoir, a bubble trap chamber coupled to the ink supply path and a outlet path from the bubble trap chamber. A second ink handling module also includes an ink supply path, a bubble trap chamber coupled to the ink supply path and an outlet path from the bubble trap chamber.

In accordance with this invention, the outlet path of the first module is coupled to the inlet path of the second module, and an ink jet is coupled to the outlet of the second module.

In accordance with this invention, the orientation of the first module is maintained such that the bubble trap chamber of the first module will remain operative while the second module with the ink jet coupled thereto is oriented as required without regard to the operation of its bubble trap chamber.

In further accordance with this invention, the bubble trap chambers of the first module and the second module include level sensing means. The level sensing means of the first module remains operative due to the maintenance of the proper orientation regardless of the orientation of the second module.

In still further accordance with this invention, the inlet path of both the first module and the second module includes valve means which is open in response to the presence of an ink reservoir cartridge. A cartridge filled with ink is inserted in the first module to open the valve while a dummy cartridge may be inserted into the second module to maintain the valve in an open position.

In still further accordance with this invention, the first module is oriented with respect to the ink jet chamber so as to create a slightly negative head at the ink jet.

In still further accordance with this invention, the level sensor may comprise at least one elongated sensor element extending substantially vertically in the first module.

In still further in accordance with this invention, the first module and the second module are substantially identical.

FIG. 1 is a partially schematic diagram of the components of an ink jet apparatus including ink handling modules which may be utilized in the preferred embodiment of the invention;

FIG. 2 is a partially schematic diagram of the modules of FIG. 1 assembled in the preferred embodiment of the invention; and

FIG. 3 is a sectional view of an ink jet apparatus in a partially exploded condition representing the preferred embodiment of the invention.

Referring to FIG. 1, the components of an ink jet system are disclosed. These components include an ink jet head 10, a first ink handling module 12, a second ink handling module 14, a coupling means 16, an ink supply cartridge 18 and a dummy cartridge 20. As shown, the ink jet head 10 includes at least one chamber 22 shown in phantom with an orifice 24 and inlet 26.

Each of the modules 12 and 14 provide ink handling capabilities including a receptacle 28a and 28b adapted to receive the cartridge 18, an inlet path 30a and 30b leading from the receptacle 28a and 28b, a bubble trap chamber 32a and 32b coupled to the ink inlet path 30a and 30b and an ink outlet path 34a and 34b coupled to the bubble trap chamber 32a and 32b. In addition, each of the modules 12 and 14 include level sensor means in the form of one or more elongated sensor elements 36a and 36b. A valve 38a and 38b which is located in the inlet path 30a and 30b prevents the outflow of ink in the absence of the cartridge 18. The valve 38a and 38b is operated by means of a coupling mechanism 40a and 40b which communicates with the receptacle 28a and 28b.

In order for the bubble trap chamber 32a and 32b in the level sensors 36a and 36b to function properly, it is necessary that the modules 12 and 14 be maintained in the orientation shown in FIG. 1. However, any ink jet apparatus need only have one bubble trap chamber which is functioning in that capacity. The same is also true with respect to a level sensor. It is therefore possible to couple the modules 12 and 14 together with the other components shown in FIG. 1 so long as the orientation of one bubble trap chamber and one level sensor is maintained to allow that bubble trap chamber and level sensor to function properly.

Referring to FIG. 2, the module 12 with its components is maintained in the proper orientation while the module 14 is inverted with the ink jet 10 coupled thereto. As also shown in FIG. 2, the coupling 60 couples the outlet path 34a to the inlet path 30b. As long as the bubble trap chamber 32a and the level sensor 36a are in the orientation shown in FIG. 2, the module 14 may be inverted or otherwise oriented and the ink jet apparatus will still function properly with the chamber 32b filled with ink and the vent 50b closed. It is also important to know the fluidic input to the ink jet head 10 is maintained to assure high performance reliable operation. The head 10 is coupled directly to the outlet 34b of the module 14 which is of course adapted to be coupled to such a head.

In order for the valve 38b to be opened, it is necessary to insert the dummy cartridge 20 into the receptacle 28b. Once this is done, the ink path to the head 10 and the module 14 are filled with ink and all necessary level sensing and bubble trapping functions are performed by the module 12.

Reference will now be made to FIG. 3 for a more detailed description of the preferred embodiment of the invention. Shown in FIG. 3, the cartridge 18 the dummy 20 are not fully inserted into the modules 12 and 14 respectively. However, it will be appreciated that the ink level shown in the modules 12 and 14 corresponds with full insertion of the cartridge 18 and the dummy 20 into the appropriate receptacles 28a and 28b. In this connection, it will be noted that hollow needle-like members 42a and 42b which are coupled to the inlet paths 30a and 30b pierce septums 44a and 44b in the cartridge 18 and the dummy 20.

In addition, FIG. 3 shows in somewhat more detail the valve 38a and 38b. Each such valve comprises a stem 46a and 46b which is biased in the upper closed position by a spring 48a and 48b in the absence of cartridge 18 and the dummy 20. In the presence of the cartridge 18 and the dummy 20, the valve 30a and 30b are opened so as permit ink to flow through in the path 30a and 30b.

FIG. 3 also shows the bubble trap chamber 32a and 32b in substantially more detail. The chamber includes a bubble trap vent 50a and 50b which may be opened and closed as required in the case of module 12, the vent 50a will be opened so as to permit the bubble trap chamber to function properly. In the case of module 14, the vent 50b will be maintained closed so as to avoid ink spilling out through the vent. The bubble trap chamber 32a and 32b also would include two parallel level sensing members 52a and 52b. Finally, bubble trap chamber 32a and 32b may include a screen leading to the outlet 34a and 34b so as prevent the flow of bubbles to the ink jet head 30.

As shown in FIG. 3, the vent 50a, with the proper orientation for the module 12, is at a vertical extremity of the chamber 32a. Similarly, level sensors 52a are vertically disposed in the module 12. In contrast, the vent 50b of the module 14 is located at a horizontal extremity while the sensor elements 52b extend horizontally. Of course, other orientations could be utilized for the module 14 without affecting the operation of the ink jet apparatus.

Finally, it will be noted that a filter 54 is employed in the outlet path 34b to the head 10. Except for the filter 54, the modules 12 and 14 are identical. This substantial identity allows a single module to be utilized alone in an ink jet apparatus as disclosed in co-pending application Ser. No. 465,474, filed Feb. 10, 1983, or a pair of modules to be utilized as shown herein. Reference is also made to the aforesaid co-pending application for various details of the module, which application is incorporated herein by reference for that purpose.

It will also be understood that the orientation of the module 12 with respect to the module 14 is intended to provide the proper relative elevation such that the pressure or head at the orifice 24 is substantially zero or only slightly negative.

It will be appreciated that assembly of the apparatus shown in FIG. 3 may proceed as follows. Initially, the coupling 16 is connected between the module 12 and the module 14. The coupling is inserted through the dummy cartridge 20 and applied over the needle-like member 42b. Ink is then caused to flow from the module 12 to the module 14. As a result, the bubble trap chamber 32b is filled. The vent 50b may then be closed. The orientation of module 14 may then be changed without effecting the operation of the system.

Although the particular modules 12 and 14 have been shown and described in detail, it will be understood that other modules may be employed having an ink jet chamber and/or level sensor mechanism requiring a particular orientation in order for the ink handling system to function properly. Other such modules will occur to those of ordinary skill in the art.

Although the details of the head 10 have not been shown and described herein, reference, is made to U.S. patent Ser. No. 336,603, now U.S. Pat. No. 4,459,601 filed Jan. 4, 1982, which is assigned to the assignee of this invention and incorporated herein by reference. Although a particular embodiment of the invention has been shown and described, it will be understood the various modifications will occur to those of ordinary skill in the art and such modifications are intended to fall within the true spirit and scope of the invention as set forth in the appended claims.