Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2000-03-28
2001-06-26
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S086000
Reexamination Certificate
active
06250751
ABSTRACT:
TECHNICAL FIELD
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.
BACKGROUND OF THE INVENTION
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 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 resistance of the biasing member is predictable and linear as it compresses and expands. However, the thin film side panels often contain wrinkles which are of random size and distribution which ultimately make the system behavior erratic and unpredictable.
A previously used method of attaching the side panels to a frame was to place the flat laminate material on the bladder frame and use a shim to depress the material some distance into the frame interior as the laminate material was being heated in order to conform the web to a cavity defined by the frame. The side panels were then heat sealed to the frame perimeter, allowing the spring to flex through a specified range of motion. This method had the undesirable effect of introducing wrinkles into the topology of the side panels.
Wrinkles or irregularities of the side panels result in sub-optimal performance characteristics such as hysteresis and erratic back-pressure/volume relationships in the ink reservoir. This erratic behavior translates into large back-pressure fluctuations during operation which can affect ink spot size, and/or timing and, ultimately, print quality. Furthermore, these problems are exacerbated in a refillable reservoir design in which the bladder spring is used both as a back-pressure device as well as a pump to refill the reservoir with ink. Hysteresis and back-pressure fluctuations can prevent the ink cartridge from being completely or reproducibly refilled with ink. What is needed, therefore, is an apparatus and a manufacturing method for the apparatus, which enables predictable and consistent back-pressure on the ink supply during use.
SUMMARY OF THE INVENTION
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. Tile method includes providing a substantially inflexible frame having at least one pressure port, the frame having at least one peripheral edge. At least one malleable web having a first side and a second side is provided. The first side of the malleable web is attached to the peripheral edge of the frame, thereby defining a substantially closed cavity. A subatmospheric pressure is applied to the cavity through the pressure port before, after or while heating the malleable web to a temperature sufficient to soften and mold the web so that the web substantially conforms to the cavity. The resulting cavity has a variable volume and a substantially predictable pressure/volume relationship. A biasing means is disposed adjacent the first or second side of the conformed web to bias the web relative to the cavity during ink use and refilling.
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 has a substantially predictable pressure/volume relationship. The ink jet cartridge also includes a substantially inflexible frame having at least one pressure port. The frame has at least one peripheral edge. At least one malleable web having a first side and a second side, is attached to the peripheral edge of the frame thereby defining a substantially closed cavity. The malleable web is conformed to the cavity by applying a subatmospheric pressure to the cavity before, after or while heating the malleable web to substantially conform the web to the cavity thereby providing a cavity having a variable volume and having a substantially predictable pressure/volume relationship. A biasing means is disposed adjacent the first or second side of the malleable web for biasing the web relative to the cavity.
In a preferred embodiment, a masking device is used during the web heating step in order to reduce irregularities to the frame walls and edges of the web caused by excessive heat applied thereto. By use of the methods of this invention, side wall or web irregularities are substantially reduced or eliminated which provides for a more uniform pressure/volume relationship in the ink reservoir. Hysteresis effects due to the aforementioned irregularities are also substantially reduced or eliminated according to the invention described herein. By substantially eliminating the side wall or web irregularities, improved performance characteristics such as ink spot size and print quality are correspondingly improved.
In the case of a refillable ink cartridge or ink reservoir, reduction or elimination of hysteresis and back-pressure variations enables in a more complete refill of the reservoir. Moreover, by masking specified areas of the ink jet cartridge before heating and applying pressure, according to the invention, side wall warping or web deformations are greatly reduced in areas not intended to be molded thereby improving the integrity of the ink jet cartridge as an ink container.
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Long Gregory Alan
Russell Matthew Joe
Whitney Jon Brock
Le N.
Lexmark International Inc.
Luedeka Neely & Graham
Vo Anh T. W.
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