Technical Field This invention relates generally to a tape cassette or cartridge presently intended for use in connection with printing or typing equipment using a pressure process to transfer dry film impressions onto an image carrying tape. The cassette includes an indicator capable of displaying the amount of tape remaining.

Cross Reference

This application hereby incorporates by refer¬ ence the disclosures of our co-pending applications filed on even date herewith with the following titles:

Precision Tape Feed and Guide Mechanism, S.N. Print Disk Positioning System, S.N.

Printing Mechanism, S.N.

Ribbon Cassette, S.N.

Electronic Tape Writing Machine, S.N.

Background of the Invention In the field of commercial art, there is a significant need for a simple means of transferring prefabricated letters or characters to a "paste-up" sheet for later photographing or printing. A dry rub- on transfer letter process is well known, however, these -materials are supplied in ^' sheets and must be- carefully aligned to produce acceptable images. Machines were later developed which prepared such let¬ ters on a continuous carrier tape. This solved many of the problems in the prior art. Such a machine is shown in PCT Publication WO 82/03600.

The carrier tape employed in such machines is used in large volume and thus the cassette holding the tape must be easy to load, capable of accurately indi¬ cating the amount of tape remaining and, above all, inexpensive to manufacture so as to keep the retail cost at a minimum. A device having all of these requirements is difficult to achieve.

The present invention discloses a unique structure which provides an accurate supply read-out with a minimum of components while achieving an easy to handle package.

Summary of the Invention Various advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, the advantages and objects obtained by its use, reference should be had to the drawings which form a further part hereof and to the accompanying descriptive matter in which there are illustrated and described certain preferred embodiments of the inven¬ tion.

Brief Description of the Drawings In the drawings, wherein like numerals refer to like elements throughout the several views:

FIGURE 1 is a perspective view of the backside of a preferred embodiment of the present invention;

FIGURE 2 is a top plan view of the cassette with a portion of a printing machine shown in which the cassette may be employed;

FIGURE 3 is a sectional view of the cassette as seen from the lines 3-3 of FIGURE 2;

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FIGURE 4 is an enlarged detail sectional view of a portion of the indicator mechanism; and

FIGURE 5 is a view taken along the lines 5-5 of FIGURE 1.

Detailed Description of the Invention Reference should be made to FIGURE 1 of the drawings which shows a perspective view of the backside of the tape cassette 610. The cassette preferably in- eludes two planar walls 612 and 614 and a peripheral side wall 616 connecting the planar walls 612, 614. For mounting purposes, a hook member 620 is affixed to the outer surface of wall 612. The tape 622 exits the cassette at aperature 624. FIGURE 2 shows the cassette installed within a typical environment wherein numeral 628 refers gener¬ ally to a printing apparatus. The top portion 630 of the peripheral wall 616 includes a slot 632 and gra¬ duations 634 which permit the indicator (described hereinafter) to show the percent or the actual amount of tape supply remaining within the cassette.

FIGURE 3 shows the cassette in place with one of the planar walls removed. There can be seen a spindle 636 generally centered within the cassette which holds a tape supply spool 638. Pivotally mounted within the cassette is a curved planar member 640 which is pivoted at one end 642 and 'has a flat portion 644 -at its other end. The curvature of member 640 is further designed to approximate the shape of the supply spool 638 at its maximum diameter. This arc of curvature is only accurate however in the center portion of curved member 640. Other embodiments could use different cur¬ vatures. The flat member 644 is preferably painted with a red color so that it is clearly visible within slot 632 (see FIGURE 2).

Indicator 640 -is biased against the tape supply 638 at all times by a bias mechanism 646 shown in FIGURES 4 and 5. This provides the extra benefit of drag on the tape so that it stays generally on the spool. In this embodiment, a coil spring 648 is affixed at one end to the curved member by wrapping a portion 650 of the curved member 640 around one of the helical coils of the spring. The spring is then seated in a socket 652 against the peripheral wall 616 of the cassette.

In operation, tape 622 is withdrawn from the supply 638 and the diameter of the spool decreases. Planar member 640 then follows a path toward the spindle to a final position 654 shown by phantom lines when the tape supply is exhausted. Because the planar wall section 616a adiacent the flat portion 644. of member 640 is preferably curved to follow the trace of portion 644, the view through slot 632 always shows an indicator approximately the same distance from the slot throughout the life of the tape supply. In this way accuracy is thus maintained.

It is preferable to locate the pivot point 642 about halfway across the transverse measurement of the cassette or approximately at the center of the curva- ture of wall portion 630.

Although some specific embodiments of the pre¬ sent invention have ^' been shown, those skilled in the art will perceive modifications which can be made without parting from the spirit of the invention. Therefore, is is intended that the scope of the present invention be dictated ^' by the appended claims rather than by the description of the embodiment.