KR830000376Y1 - Tape reel for video cassette - Google Patents

Abstract

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Description

Tape reel for video cassette

1 is a side view of one embodiment of a tape reel for a conventional video cassette.

2 is an enlarged longitudinal cross-sectional view taken along the line II-II of FIG.

3 is an enlarged cross sectional view taken along the line III-III of FIG.

4 is a cross-sectional view similar to FIG. 3 as one embodiment of a tape cassette for a video cassette to which the present invention is applied.

5 and 6 are plan and bottom views of the embodiment shown in FIG.

The present invention relates to a high precision tape reel for use in video cassettes.

With the recent increase in video tape recorders, it is necessary to produce large-scale video cassettes in which video and sound recording magnetic tapes are embedded between two cassette halves, while increasing the operation time for a certain length of tape. This recorder design trend has been accompanied by the demand for high image reproduction. In this way, the image reproducibility of the video recorder depends not only on the magnetic tape itself, but also on the tape reel on which the magnetic tape is wound and the dimensional precision of the two cassette halves.

Tape reels have various specifications that match the total regeneration time of the tape wound on the tape reel and the regeneration system used by a particular manufacturer, but they are molded from plastic and usually have the same structure.

In particular, a tape reel embedded between two cassette halves typically consists of a pair of flanges and a hub, the tape being wound on the hub. One flange and the hub are integrally molded to achieve optimum manufacturing efficiency, and then the other flange is bonded to the remaining free end of the hub during assembly of the cassette. The hub has a central cavity provided with the receiving of the video tape recorder spindle and an engagement rib with the spindle. In the reproduction of video images recorded on magnetic tape wound on the hub, incomplete engagement between the spindle of the video tape recorder and the hub will cause wow / flutter. The running of the tape is also adversely affected by variations in the thickness of the integrally formed hub and flanges and any sink marks that may occur at the interface between the flange and the hub. These changes and sink marks, however, are likely to occur due to the flow of synthetic resin for flanges into the area intended for the hub in the generally adopted molding process.

The main object of the present invention is to be independent of the misalignment of ribs engaged with the spindle of a video tape recorder, to have a high uniformity distribution characteristic, and to be rational for the integral forming of the hub and the flange to avoid defects in the overall structure and the dimensional accuracy. A high precision dimension tape reel for a video tape cassette is provided.

The video cassette tape reel according to the present invention includes a pair of flanges and a hub connected to a pair of flanges, wherein the hub has an outer cylindrical wall having an outer surface on which the tape is wound and an inner cylindrical wall in which the spindle of the video tape recorder is accommodated. The inner surface of the inner cylindrical wall is provided with a plurality of protruding ribs for complete engagement with the spindle and the outer surface with a plurality of notches so that the thickness of the inner cylindrical wall is uniform throughout.

Since the inner cylindrical wall of the hub with ribs is molded to a uniform thickness, the injected synthetic resin in the injection molding process contracts internally uniformly upon cooling. Therefore, the design of the hub in consideration of the shrinkage can produce a product of high precision dimensions. In addition, the fact that the ribs have a uniform thickness means that all parts of the hub can be made to have a uniform thickness, and as a result, the hub portion acts as a runner, through which the synthetic resin passes through and integrally. In the case of reaching the erected flanges, this means that the flow rate of the resin can be even in all parts of the hub. Thus, the synthetic resin can be injected at a uniform rate throughout the entire area of the wide but thin flange cavity to obtain a uniform resin distribution. As a result, the flanges are independent of local irregularities that may result from deformation caused by non-uniform curing. This also contributes to the dimensional precision of the reel.

Other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

1 to 3 show a tape reel in which the tape is wound in the form of a main drive portion, i.e., a cassette generally used. In the finished video cassette, a tape reel is installed between two cassette halves and a magnetic video recording tape is wound on the tape reel. Since the rotation speed of the tape reel affects the quality of the video image reproduced by the video tape recorder, a high degree of dimensional accuracy is required.

The conventional tape reel has a pair of flanges 1 coupled to the central hub 2. One flange is integrally formed with the hub, and the other flange is separately molded and attached to the remaining free end of the hub by ultrasonic welding or similar methods. The tape is of course wound on the outer surface 2a of the hub 2.

Referring to the enlarged vertical cross sectional view of the hub shown in FIG. 2 (along line II-II of FIGS. 1 and 3) and to the enlarged cross-sectional view shown in FIG. 3 (along line III-III of FIG. 1), The end of the hub to which the separately molded flange is attached has a nub 3 projecting at a position corresponding to the central axis, which is pressed by an elastic member in the cassette casing of the video tape recorder.

The end of the hub also has a fixing protrusion 4 which is passed through a hole in the flange 1b of the corresponding position and then welded to the flange 1b by ultrasonic welding or the like. .

The opposite end of the hub 2 is a second flange 1b molded integrally with the hub 2 or attached to the hub after molding. The flange 1b has an opening drilled into the cylindrical cavity 5 inside of the hub 2 to receive the tape drive spindle of the video tape recorder. It is well known that the spindle has a plurality of ribs projecting radially at appropriate intervals.

On the other hand, the inner cylindrical wall defining the cylindrical space 5 has a plurality of ribs 6 projecting radially in the cylindrical space 5, positioned at appropriate intervals and extending in the axial direction of the hub. Thus, when the spindle of the video tape recorder enters the cylindrical space 5, the ribs of the spindle engage the recesses 7 formed between the neighboring ribs 6, so that the spindle and the reel are functionally interconnected. It can rotate as a fuselage.

In addition to the structures generally described above, the tape reel 9 defines an outer cylindrical wall 8 constituting the outer surface 2a of the hub and an inner cylindrical wall 9 defining a cylindrical space 5 for accommodating the spindle of the video tape recorder. It is a double wall structure with), and these cylindrical walls (8), (9) are usually joined by a plurality of spokes (10).

Such a structure is not only economical in terms of the quantity of material required. Since it is effective in minimizing the thickness of the hub wall member in the radial direction, there is an advantage that non-uniform curing occurs during molding after the curing process, thereby preventing deformation that increases the wall thickness and volume.

The most important factors necessary for the high precision of this reel are the position and workability of the center nub 3, the outer diameter and workability of the hub 2, the inner diameter of the rib 6, the positioning accuracy, workability and strength uniformity. Can be mentioned. However, in this reel, while it is possible to obtain about the same density as designed for the outer diameter of the center nub and hub, there is a significant problem with regard to the formation of the interlocking rib 6.

This is because the thickness of the inner cylindrical wall 9 is thicker in the portion (9a) in which the ribs 6 are formed than in the portion (9b) in which the recesses 7 are formed, and thus uniform in these two portions. This is because there is a difference in strength that damages the stress distribution. Furthermore, since the portion 9a has a considerable thickness, it is susceptible to deformation due to non-uniform curing (the outer portion is rapidly cooled and the inner portion is gradually cooled) in molding after the curing process, as briefly mentioned above.

In addition to the problems associated with the ribs 6, a problem in which molding defects called so-called sink marks are likely to occur at the boundary between the hub and the flange formed integrally is also seen in the conventional structure, which is a cylindrical cavity (5). Since the point P in the upper center of is generally selected as the inlet of the injection molding process, the injected synthetic resin has a relatively small passage corresponding to the integrally formed flange 1b through a relatively large passage corresponding to the rib 6. This is because the flow rate of the injected synthetic resin changes as it passes.

Hereinafter, the tape reel according to the present invention has a structure that prevents occurrence of molding defects in the process of forming ribs and other parts, and also prevents generation of sink marks.

4 is a cross-sectional view of the conventional tape reel shown in FIG. In the following description, the same reference numerals are used for elements of the tape reel according to the present invention corresponding to the conventional tape reels shown in FIGS. 1 to 3. Comparing the conventional tape reel shown in FIGS. 1 to 3 with the tape reel of the present invention, the tape reel according to the present invention has a notch extending in the axial direction to the rib 6 as shown in FIG. It can be seen that 11 is provided. That is, it can be seen that the notch is provided on the outer surface portion of the thick inner cylindrical wall where the rib is provided. As a result, it can be seen that the rib has a shape having a predetermined thickness 9a ', as shown in FIG.

Each notch 11 has an upper edge 9C of the inner cylindrical wall 6 of the hub 2 from the end of the hub 2 to which the integrally formed flange is attached, as is clearly shown in FIG. ). The notch 11 divides the upper edge 9C of the inner cylindrical wall into a plurality of parts.

According to such a structure according to the present invention, the molding deformation which may occur due to excessive thickness of the rib 6 is prevented, and at the same time, between the coupling portion and the rib portion between the hub 2 and the flange 1b during the molding process There is almost no difference in volume and cross section, the change in the flow rate of the synthetic resin is reduced, and the overall deformation of the tape reel is localized.

As mentioned above, the inlet of the conventional tape reel is located at the center of the ceiling surface of the cylindrical cavity 5 which accommodates the spindle of the video tape recorder, so that the trace of the inlet of the small projection after molding remains. However, since the projection inlet trace is in contact with the upper portion of the spindle, even if the present invention is applied, the problem of precision remains. However, this problem is, for example, by moving the position of the inlet to the upper central portion of the nut (3), as shown in the dashed line C in Figure 2 to form a hollow in the nub (3) the trace of the inlet hole is greater than the height of the nub Can be solved by moving the inlet to position G (FIGS. 2 and 5) at the tip of the fixing projection 4 of the separately formed flange 1a. This ensures that no matter what form the inlet trace remains, during the ultrasonic welding process for bonding the flange 1a and the hub 2, the inlet trace is flattened with the fixed protrusion 4 and the fixing protrusion 4. There is no inlet trace on the tape reel.

In order to apply the present invention efficiently, it is preferable to uniformize the flow rate of the synthetic resin water to the distal end of the integrally formed flange 1b, which is shown in FIG. 6 and the outside of the inner cylindrical wall 9 and the flange. This is accomplished by providing a plurality of spokes 12 along the rear face of the flange 1b between the perimeters. When the spokes 12 are installed between the inner cylindrical wall 9 and the second cylindrical wall 8 'coaxially arranged, a reservoir is formed in the runner at a portion where the opposite side of the hub 2 and the flange 1b are coupled. This is particularly useful because of the smooth flow of the resin.

In the figure, since the cut portion 13 is not directly related to the present invention as a tape end holder, its description is omitted here.

As is apparent from the above description, the ribs having excessive thickness in the prior art have a uniform and thin predetermined wall thickness according to the present invention, resulting in satisfactory results in dimensional accuracy, molding characteristics and strength distribution.

Claims (1)

A pair of flanges and a hub coupled to the flange, the hub having an outer cylindrical wall having an outer surface on which the tape is wound and an inner cylindrical wall having an inner cavity for receiving the spindle of the video tape recorder, the inner cylindrical wall of The inner surface is provided with a plurality of ribs with regular spacing extending axially in the cavity for engagement with the spindle, wherein the inner cylindrical wall portion provided with the ribs is more than the inner cylindrical wall portion between adjacent ribs. A tape cassette for video cassette, which is thickened, wherein the notch (11) extending in the axial direction is formed in the rib (6).