This invention relates to the field of ink jet printers. More particularly, this invention relates to an improved ink jet printer cartridge and a manufacturing method therefor.
Ink jet printers require an ink supply to be in fluid contact with an ink drop ejecting device which precisely ejects ink onto a recording media. The ink supply must be maintained at a relatively constant pressure to keep the ink from discharging from the ejecting device at the wrong time or in an undesired amount. There are several methods and devices for maintaining a constant negative back-pressure including capillary fibers or foam, bladder-type configurations and lung-type configurations.
Bladder and lung configurations are preferred since they may be configured to provide a smaller volume ink reservoir for the same quantity of ink contained in a foam or fiber filled reservoir. Such bladder and lung devices may consist of a rigid frame with either one or two side panels made of a thin plastic laminate material. Both configurations depend on a flexing of the side panels which is resisted by a biasing member located either between the side panels (bladder configurations) or between one of the side panels and a rigid panel attached to the frame (lung configurations). The side panels are typically heat welded or adhesively attached to a substantially rigid frame. While heat welding is an effective, less time consuming and less costly method of attaching the flexible panels to a rigid frame, improvements in heat welding techniques are needed to increase useable product yield and provide a less fragile lung or bladder construction.
The foregoing and other needs are provided by an improved ink cartridge for an ink jet printer and improved manufacturing method therefor. According to the invention, a method for manufacturing a pressure control device for an ink jet cartridge is provided. The method includes providing a thermoplastic, flexible web having an edge portion, a first side and a second side and providing a substantially inflexible frame member having at least one peripheral edge. The first side of the flexible web is disposed adjacent the peripheral edge of the frame, thereby defining a substantially closed cavity. The edge portion of the web and peripheral edge of the frame are heat welded to one another using a heated platen, the heated platen having a heating surface and the peripheral edge having a bonding surface. The heat welding step is preferably conducted with a structure selected from the group consisting of an angled platen for heat welding the web and peripheral edge, a conventional platen for heat welding an angled peripheral edge and an angled platen for heat welding an angled peripheral edge whereby a bond is formed between the flexible web and the bonding surface at a temperature and pressure which minimizes thinning of the flexible web on the bonding surface at least adjacent the substantially closed cavity and wherein an angle providing the angled platen or angled peripheral edge relative to a plane defined by the flexible web ranges from about 5 to about 45 degrees.
In another aspect the invention provides an ink jet pen for use in an ink jet printer. The pen includes an ink jet cartridge body and ink jet cartridge attached to the cartridge body. The ink jet cartridge contains ink and a pressure control device is disposed therein for maintaining a substantially constant pressure in the ink jet cartridge. The ink jet cartridge includes a substantially inflexible frame having at least one peripheral edge. At least one thermoplastic, flexible web is provided having an edge portion, a first side and a second side. The edge portion of the first side of the flexible web is heat welded to the peripheral edge of the frame thereby defining a substantially closed cavity. The edge portion and peripheral edge are heat welded to one another at a temperature and pressure sufficient to provide a reinforced web edge portion. The heat welded flexible web is preferably provided by a heat welding structure selected from the group consisting of an angled platen for heat welding the web and peripheral edge, a conventional platen for heat welding an angled peripheral edge and an angled platen for heat welding an angled peripheral edge and wherein an angle providing the angled platen or angled peripheral edge relative to a plane defined by the flexible web ranges from about 5 to about 45 degrees.
By heat welding the edge portion of the flexible web and peripheral edge of the frame to one another with an angled heated platen, an angled peripheral edge, or both an angled platen and angled peripheral edge, the edge portion of the web is substantially reinforced with respect to the frame. As compared to a pressure control device for an ink jet cartridge made with a standard, non-angled platen and/or peripheral edge, the pressure control device made according to the invention withstands mishandling to a greater degree thereby providing a higher yield of usable parts. The ink cartridges containing such pressure control devices are also substantially more reliable for long term use due to less thinning of the web edge portion adjacent the closed cavity during the welding or bonding process.