Torsion spring

Details Torsion spring Torsion spring

1999-09-30

2001-06-05

Oberleitner, Robert J (Department: 3613)

Spring devices

Vehicle

Torsion

C267S189000, C267S273000, C267S258000, C267S276000

Reexamination Certificate

active

06241224

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to torsion springs.
BACKGROUND OF THE INVENTION
The features of the present invention are useful in many machines that use torsion springs. One such machine is an electrophotographic printer. Electrophotographic printing is a well-known and commonly used method of copying or printing documents. Electrophotographic printing is performed by exposing a light image representation of a desired document onto a substantially uniformly charged photoreceptor. In response to that image the photoreceptor discharges so as to create an electrostatic latent image of the desired document on the photoreceptor's surface. Toner particles are then deposited onto that latent image so as to form a toner image. That toner image is then transferred from the photoreceptor onto a substrate such as a sheet of paper. The transferred toner image is then fused to the substrate, usually using heat and/or pressure. The surface of the photoreceptor is then cleaned of residual developing material and recharged in preparation for the production of another image.
Electrophotographic printers are comprised of a large number of individual components, including numerous mechanical devices. One frequently used mechanical device is the torsion spring. Torsion springs are commonly used to bias one element, such as a roller, toward another element, such as a stack of paper.
While torsion springs and their applications are well known, they are typically comprised of multiple parts, such as end caps and a spring steel element, that must be assembled. Such assembly is expensive, time consuming, and often difficult. Therefore, a new type of torsion spring that does not require assembly of individual components would be beneficial.
SUMMARY OF THE INVENTION
The principles of the present invention provide for a new type of torsion spring that does not require assembly of individual components. A torsion spring according to the present invention is useful for joining a first member with a second member along a longitudinal axis, wherein the second member rotates about the axis from a first position to a second position. That torsion spring includes a first molded plastic end for mating with the first member, a second molded plastic end for mating with the second member, and an elastic member that connects the first and said second plastic ends together. The elastic member is designed to provide a force that biases the second member from the second position toward the first position. Beneficially the elastic member is comprised of a plurality of plastic arms that are molded together with the first and second plastic end caps. Alternatively, the elastic member is beneficially comprised of a rubber tubular element.


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