WO1995015560A1

WO1995015560A1 - Reel springs for magnetic tape cassettes

Info

Publication number: WO1995015560A1
Application number: PCT/US1994/014009
Authority: WO
Inventors: Michael C. Carrol
Original assignee: Jason Incorporated
Priority date: 1993-12-03
Filing date: 1994-12-05
Publication date: 1995-06-08

Abstract

A magnetic tape cassette has an improved arrangement of reel springs (18, 20) wherein each tape reel is biased by its own, individual spring. Each reel spring has an elongated, generally rectangular shape defined a longitudinal axis (C). An attachment element (22) at one end of each spring is fixed to a surface (12) of the cassette housing (10). A fold or bend line (28) defines a spring arm (30) with a free end (24) that extends away from the housing surface and into contact with the reel hub. The two springs are co-linearly mounted in the housing such that they are symmetrical about the transverse centerline (B) of the housing with the attachement elements closer to the centerline than are the free ends.

Description

Background of the Invention This invention relates to magnetic tape cassettes suc as the type commonly used in video cassette recorders. The invention is particularly concerned with an improved arrangemen for the springs for the tape reels in a magnetic tape cassette. Magnetic tape cassettes generally comprise a pair of tape reels enclosed in a housing. The tape reels include hubs which are rotatably mounted on the tape cassette base. A reel spring is fixed to the underside of the cassette cover.

Typically, the spring is stamped from a piece of stainless stee and is formed with two elongated arms extending from a central, flat base. The base is fixed to the underside of the cassette cover and the arms are curved or bent in a manner such that the extend away from the cover toward the tape reel hubs. The free ends of the arms contact the hubs and bias the hubs downwardly, such that the hubs are rotatably retained in a fixed position. The application of a reel spring in a tape cassette is shown in U.S. Patent No. 4,770,367. Various efforts have been made to reduce the cost of reel springs while maintaining their fairly stringent performan specifications. Since reel springs are generally formed from expensive stainless steel, cost is most effectively reduced by minimizing the amount of material used to make an operable spring. One approach to reducing the amount of material needed to nake a spring is to reduce the wid^~h of the spring. Others have attempted to cut costs by minimizing the thickness of the spring. The operating characteristics of such springs are maintained in a functional range by forming strengthening "rib or projections in the surface of the spring. U.S. Patent 4,662,579 discloses such a spring.

As mentioned above, many prior art springs have a central base portion with two arms extending from the base. Typically the base is a longer or larger piece than is strictl necessary for anchoring the arms to the cassette housing. Thi results in more material being used to make the spring than is necessary. Splitting the one-piece spring into two saves this wasted material. With a two-piece "spring" (actually there ar two separate springs), each tape reel has its own spring which has a minimal base portion for attachment purposes . Prior art cassettes using a dual spring approach are shown in the following United States Patents: Schoettle 4,629,144, Iwahashi 4,802,044, Nishimura 5,181,153, Kondo 2,214,647 and Yamaguchi 5,216,565. But none of these patents show an arrangement of the springs which can be readily sub- stituted for the previously-used one-piece spring. The spring in this group of patents are mounted perpendicular to the longitudinal centerline of the cassette. The mounting locatio in these patents requires the springs to be separately install at the time of the cassette's assembly. Satoyoshi 4,685,638 h a two-spring cassette but its springs are mounted to the edges the housing and are not suitable for use in a cassette origina intended for a one-piece spring. Gelardi et al, U.S. Patents

5,092,536 and 5,114,092 show two plastic reel springs molded into the housing so assembly of stainless steel springs is not issue in this construction.

Summary of the Invention This invention relates to magnetic tape cassette reel springs and a mounting arrangement therefor which reduce the cost of the springs by allowing them to be manufactured with le material, without compromising the performance specifications which must be met in order for the springs to operate properly. Accordingly, this invention provides two reel springs that are fully functional for their intended purpose but each spring has a mounting portion or attachment element which is smaller than similar springs described in the prior art. The springs of the present invention can be substituted for a one- piece spring and used in cassette housings designed for a one- piece spring with little or no alteration of the housing. The reel springs have a shape which is simple to manufacture in hig volume production and reduces material waste.

The magnetic tape cassette reel springs and mounting arrangement therefor comprise two elongated strips of resilient material, each formed in a generally rectangular configuration. Each strip has first and second parallel edges which extend substantially along the entire length of the strip. Each sprin has a flat attachment element: bounded by a transverse crimp or fold line which defines an arm. The arm extends at an angle t the plane of the attachment element to a free end.

The springs are mounted in the cassette housing with their attachment elements being secured to the housing by a rivet, screw or the like. Preferably a non-round opening in t attachment element receives a non-round peg which is molded in the housing. After placement of the springs on a peg, the peg are welded or otherwise staked to the spring. When mounted, t longitudinal axes of the springs are co-linear, with the attac ent elements being closer to one another than the free ends.

The net effect of the spring configuration and mount arrangement of the present invention, compared to one-piece springs of the prior art, is to fasten the springs closer to t free ends and to eliminate the base material between the rivet But by arranging the two springs of the present invention co- linearly and along the same spring axis as in prior art one-pi spring cassettes, little or no alteration to existing cassette designs is required. This permits direct substitution o£ the less expensive springs of the present invention for more expensive prior art one-piece springs, without incurring offsetting cost increases for housing alterations. Thus, the present invention can be viewed as the functional equivalent o "one-piece" spring with a large hole in the base portion, so large in fact that it divides the spring into two pieces. Brief Description of the Drawings Fig. 1 is a bottom plan view showing the interior of upper cassette housing section with the springs of the present invention mounted therein.

Fig. 2 is a partial section through the upper cassett housing section and through the springs. The springs' thicknes is exaggerated in this view for clarity.

Fig. 3 is a view similar to Fig. 1 showing an alterna embodiment.

Fig. 4 is a section similar to Fig. 2 showing the alternate embodiment.

Detailed Description of the Invention The general outlines of a magnetic tape cassette cove or upper housing section are shown in Fig. 1. The cover 10 includes a central panel 12 having a pair of windows 1 . The panel is surrounded by a perimeter wall 16. It will be under¬ stood that the cover adjoins a similarly-shaped cassette base section (not shown) to form the complete cassette housing. The cover has a rectangular shape that defines a longitudinal centerline A and a transverse centerline B.

First and second reel springs 18 and 20 are fastened the inner surface of the central panel 12 by pegs 22 which extend through holes in the spring. Preferably the holes and pegs are non-round, such as the rectangular configuraticn show This prevents unwanted rotation of the springs on the pegs.

Preferably the springs are heat staked on the pegs. Other fastening methods could be used such as adhesives, screws or t like. The springs themselves are elongated strips of stainless steel, generally rectangular but with rounded free e 24. The strip of stainless steel has first and second paralle edges which extend throughout the length of the spring and def a spring axis C. Each spring has a planar attachment element 2 at the end opposite the free ends 24. The attachment element adjoins the central panel 12 and contains the holes or openings for the pegs 22. The attachment element 26 is no larger than necessary for receiving the peg.

A fold line or bend line 28 defines an arm 30 which extends out of the plane of the attachment element 26 and, cons quently, away from the central panel 12 toward the interior of the cassette. The arm 30 terminates at the free end 24. The effect of this configuration is a cantilevered mounting of springs 18 and 20. The springs 18 and 20 are mounted such tha they are co-linear. Also, the springs are arranged so their attachment elements 26 are the spring parts closest to one another. In other words, the attachment elements are in facin relation. Preferably the springs are mounted on the longitudi centerline of the cover and the springs are symmetric about th transverse centerline. Figs. 3 and 4 show an alternate embodiment which differs from that of Figs. 1 and 2 in that an extra fold line o crimp 32 is placed in the arm of each spring to impart an overa curved configuration to the spring. Another variation in Fig. is the use of projections 34 on either side of the springs as a anti-rotation device. The projections could be used either in conjunction with or as an alternative to the non-round holes in the attachment elements. The Fig. 3 version shows round pegs 3 could be used if the anti-rotation projections 34 are present. While a preferred form of the invention has been show and described, it will be realized that changes may be made thereto without departing from the scope of the following clai

Claims

Claims :

1. A magnetic tape cassette housing comprising a generally rectangular cover defining longitudinal and transvers centerlines, first and second elongated reel springs each havin first and second parallel edges extending substantially through out the length of the spring and defining a spring axis, a planar attachment element at one end of the spring, and an arm extending from the attachment element and at an angle to the plane thereof, the attachment element of each spring being fixe to the cover to mount the springs thereon, the springs being arranged with co-linear axes and with the attachment elements i facing relation.

2. The structure of claim 1 wherein the springs are mounted on the longitudinal centerline of the cover.

3. The structure of claim 1 wherein the springs are mounted symmetrically about the transverse centerline of the cover.

4. The structure of claim 3 wherein the springs are mounted on the longitudinal centerline of the cover.

5. The structure of claim 1 wherein the attachment elements of the springs are spaced apart.

6. The structure of claim 1 wherein the springs have fold line in the arm, the fold line being spaced from the attachment element.

7. A magnetic tape cassette housing comprising a generally rectangular cover defining longitudinal and transvers centerlines, first and second elongated reel springs each havin a planar attachment element at one end of the spring, and an ar extending from the attachment element at an angle to the plane thereof and terminating at a free end, the attachment elements the springs being fixed to the cover on the longitudinal centerline, intermediate the free ends of the arms.