Spring devices – Elastic extension devices – Tension spring
Reexamination Certificate
1999-11-12
2001-07-17
Hilten, John S. (Department: 2854)
Spring devices
Elastic extension devices
Tension spring
C267S174000, C267S251000, C400S234000, C242S422400
Reexamination Certificate
active
06260834
ABSTRACT:
BACKGROUND
1. Technical Field
The present disclosure relates to tensioner apparatus. In particular, the disclosure relates to ribbon supply tensioners for use in printing apparatus.
2. Description of the Related Art
In modern printers, a variety of feed and take-up mechanisms are required to be driven and/or wound in order to transport printing media, ribbon, backings, etc. In most applications, these feed and take-up mechanisms require tensioning structure to maintain a desired amount of tension on the transport system and to minimize or eliminate roll out. One structure used in the art to provide tension is a clutch mechanism. Such a mechanism typically includes a friction plate intended to impart a predetermined torque to the feed and/or take-up mechanisms during operation. See, for example, U.S. Pat. No. 4,797,690. Although adequate for their intended function, these clutch mechanisms are typically expensive and require several assembly/adjustment steps to insure proper operation.
One simple and inexpensive tensioning mechanism is the wrapped coil spring developed by Fargo Electronics Inc. for a ribbon supply system in the Prodigy Plus™ thermal transfer printers. In that system, a single coil spring was wrapped around a pulley connected to the ribbon supply system. Each end of the spring was anchored to the housing such that about 180° of the periphery of the pulley was continually engaged by the spring. In this manner, a continuous tensioning was applied and was directly proportional to the spring constant K of the coil spring and the length of extension. While this system was adequate and inexpensive, it did not allow for adjustments for different media and gave little or no recoil when the pulley direction was reversed. Thus, wrinkling and/or tearing or the ribbon supply could result.
Accordingly, a need exists in the art for a simple, versatile, adjustable tensioning system which is configurable for different media and can impart a useful degree of recoil regardless of rotational direction.
SUMMARY
A pulley tensioner for applying torque or tension to a pulley is disclosed which includes a spring system configured to at least partially encircle the periphery of the pulley. The spring system is anchored to the pulley housing or some other fixed location by either an elastic or inelastic member. The spring system is made up of one or more coil springs which springs are wrapped at least partially around the periphery of the pulley. In one embodiment it is contemplated that each spring has a different spring constant and length. This allows the operator to select the desired tension depending on the operating parameters of the printer. The applied tension may be further modified or tuned by using one or more springs to anchor the spring system to the pulley housing or some other fixed location.
This novel system provides a versatile torque adjustment capability while increasing desirable recoil in either forward or reverse rotational directions.
REFERENCES:
patent: 1815064 (1931-07-01), Legg
patent: 3842620 (1974-10-01), Scozzafava
patent: 4074873 (1978-02-01), Hayashi et al.
patent: 4797690 (1989-01-01), Takita et al.
patent: 4886385 (1989-12-01), Cappotto
patent: 5284396 (1994-02-01), Masumura et al.
patent: 60-124279 (1985-07-01), None
patent: 63-297085 (1988-12-01), None
patent: 5-193221 (1993-08-01), None
Colonel Kenneth
Tobin Dwayne
Datamax Corporation
Dilworth & Barrese LLP
Grohusky Leslie J.
Hilten John S.
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