Pressure-sensitive accumulator for ink-jet pens
AssigneeHewlett-Packard Company
InventorsBruce Cowger, Marc A. Baldwin, Fred E. Tarver, Gary D. Tarver, John G. Wydronek, George M. Custer
Life of this patent
Estimating the term…
Abstract
The accumulator regulates changes in the back pressure of an ink-jet pen reservoir so that ink does not leak from the pen print head and so that the print head is able to completely empty the reservoir of ink. The accumulator includes a flexible bag that is mounted to a flat curved spring. The elasticity of the spring tends to contract the bag as the bag expands in response to back pressure reduction in the reservoir.
Claims40
An accumulator apparatus comprising:
- an expandable and contractible bag;
- mounting means for mounting the bag within a fluid volume of a particular size so that expansion of the bag decreases the size of the fluid volume, the bag including an opening arranged so that an interior of the bag is in communication with ambient air outside the fluid volume;
- and
- a spring disposed within the fluid volume and having a first portion that assumes a curved relaxed state, part of the bag being adjacent to one side of the curved first portion, the bag part being urged by the spring to be substantially fully contracted when the spring first portion is in the relaxed state.
The apparatus of claim I wherein the first portion of the spring has a convex surface whenever the first portion is in a relaxed state, the bag part being adjacent to the convex surface.
An accumulator apparatus comprising:
- an expandable and contractible bag;
- mounting means for mounting the bag within a fluid volume of a particular size so that expansion of the bag decreases the size of the fluid volume, the bag including an opening mounted so that an interior of the bag is in continuous communication with ambient air outside the fluid volume, wherein the bag is formed of flexible material and is contractible into a generally flat configuration and
- wherein the fluid volume is defined by a reservoir, the reservoir being sealed and containing ink therein under a back pressure, the back pressure being present irrespective of whether the bag is expanded or contracted.
An accumulator for an ink-jet pen that has a substantially sealed reservoir volume, comprising:
- a spring;
- and
- an expandable and contractible bag attached to one side of the spring, the spring and bag being positionable within the reservoir volume, the bag including an opening arranged so that an interior of the bag is in communication with ambient air outside of the reservoir volume, the bag and spring being attached adjacent one another so that the bag expands to deflect the spring as fluid pressure inside the reservoir volume decreases relative to pressure of the ambient air outside of the reservoir volume.
An accumulator apparatus comprising:
- a sealed reservoir for containing ink and having a back pressure established therein;
- an expandable and contractible bag mounted within the reservoir, the bag having an opening therein arranged so that an interior of the bag is in communication with ambient air outside of the reservoir, the bag being arranged so that contraction of the bag increases back pressure in the reservoir;
- and
- a print head mounted to the reservoir and adapted for ejecting ink drops from the reservoir.
A method for making an accumulator apparatus, comprising the steps of:
- attaching an expandable and contractible bag to a spring so that when the spring is in a relaxed state the bag will be substantially contracted;
- configuring the bag and spring so that the bag will expand and deflect the spring whenever a pressure difference between the fluid inside and outside of the bag exceeds a predetermined minimum level;
- and
- supporting the bag and spring to maintain the interior of the bag in fluid communication with fluid outside of the bag thereby to define an unobstructed path for fluid movement into and out of the bag.
An accumulator apparatus for an ink reservoir of a pen comprising:
- an elongated spring member mounted inside the reservoir and shaped to resile to a relaxed state and to resist deflection out of the relaxed state;
- an expandable and contractable bag mounted along the length of the spring member so that expansion of the bag deflects the spring member and so that contraction of the bag permits the spring member to resile toward the relaxed state;
- and
- shaping means for reducing along only a portion of the length of the spring member the resistance of the spring member to deflection caused by bag expansion.
Dependencies are inferred from the claim text.