JPH03181084A - Manufacture of separate sheet - Google Patents

Abstract

PURPOSE:To improve the cushion property of a separate sheet by forming plural insular projecting parts projecting to the tape side on the plane separate sheet and forming plural insular projecting parts projecting to the half case side there. CONSTITUTION:A separate sheet 1 is provided with not only plural trapezoidal or domic projecting parts (dowels) 2 projecting to the side of a tape 3, a window 5, and holes 10 but also second dowels 6 projecting to the side of a cassette half 4. Consequently, the separate sheet 1 is held above the half 4 by dowels 6, and dowels 2 are brought into contact with the tape winding surface. Thus, the height of dowels 2 on the separate sheet 1 is not increased and second dowels 6 projecting in the direction opposite to dowels 2 are formed, and the cushion property of the separate sheet is improved to adjust the winding appearance of the tape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a separate sheet for a cassette tape.

[Prior Art] Cassette tapes generally use high-density polyethylene or tetrafluoroethylene, such as graphite Teflon (trade name of Du Bont), between the tape and the half case to make the tape run smoothly. A separate sheet made of a composite of plastic and lubricant is interposed. In that case, interposing the separate sheet between the tape and the half case requires a clearance greater than the thickness of the separate sheet, and if this clearance is not provided, frictional force during tape running increases. On the other hand, if the clearance is too wide, the tape may be wound in an untidy manner and the edges of the tape may be damaged.

Therefore, it has been proposed to provide separate sheets with curls or various creases so that the frictional force during running of the tape does not increase even if the clearance is small.

However, these curls and creases also have a linear contact with the tape, so the effect of reducing frictional force is still not sufficient, and the shape of the curls and creases is difficult to determine, making it difficult to control the clearance.

In addition, in recent years, the required quality of cassette tapes and the like has become extremely high, and in particular, it is necessary that the winding form (the winding of the magnetic tape wound around the hub) be well-defined. This is because when a difference in winding or uneven winding occurs due to a combination of play, fast forward (FF), and fast reverse (RW), the tape comes into strong contact with the separate sheet, increasing torque and placing a large load on the winding motor of the deck. This may cause the vehicle to stop running, or
Furthermore, if there are steps or irregularities in the winding during tape playback, the irregular winding portions are unraveled during playback, and the load torque suddenly decreases, causing fluctuations in tape tension. This tape fluctuation causes the tape to snack slip or change its position relative to the playback head, resulting in fluctuations in the playback output.
The quality of the tape is extremely poor. It goes without saying that if the roll is neatly shaped, the appearance will be beautiful and the product value will increase.

A separate sheet with protrusions (dowels) proposed by the present applicant that improves the above-mentioned drawbacks is known.

As shown in FIGS. 1(a) and 1(b), this is a separate sheet 1 provided with a large number of dome-shaped or trapezoidal projections (dowels) 2. Note that 5 is a see-through window for viewing the amount of tape, and 10 is a hole for a tape drive shaft. This separate sheet is interposed between the tape 3 and the half case 4, as shown in FIG. 2, with the dowels facing the tape. Although the dowel does not necessarily make point contact with the tape, it has a small area and good cushioning properties, so most of the above-mentioned drawbacks can be solved.

[Problems to be Solved by the Invention] However, as of now, no satisfactory solution has been found regarding tape winding. According to research conducted by the present applicant, it has been found that the appearance of tape winding can be adjusted by increasing the height of the dowels of the separate sheet. However, increasing the height of the dowels is nothing but deep drawing in the drawing process when manufacturing separate sheets, but due to the limitations of the sheet material, if the dowels are drawn too deeply, the sheets may tear at the doweled parts. occurs. To explain this point more specifically,
As shown in Fig. 3, a dowel processing machine generally consists of a female mold 7 having an opening that almost corresponds to the solid size of the dowel, and a male mold 9 that fits into this opening and has a protrusion for separating sheets. The material 8 is inserted between the molds as shown in FIG. 3(a), subjected to drawing processing as shown in FIG. 3(b), and a protrusion (dowel) 2 is formed as shown in FIG. 3(C). Ru. The amount of reduction of the dowel can be expressed by the height h of the dowel, but this amount of reduction is limited by the material and thickness of the sheet material 8. One of the reasons is the problem of tearing, and the other is the problem of wrinkles. That is, when the amount of squeezing is increased, the dowel 2 forms an annular or arc-shaped tear 11 as shown in FIG. Furthermore, even if the sheet is not drawn so deep that it tears, if the amount of drawing is large, wrinkles will occur between the dowels that are left on the sheet due to the strain caused by the drawing process, as shown in FIG. 5. FIG. 5(a) shows a point where wrinkles occur when viewed from a plane, and FIG. 5(b) shows a cross-sectional view of the wrinkles. When wrinkles occur, it is difficult to control the dowel height ff1h, and the cushioning effect of the dowels also deteriorates. Needless to say, it also doesn't look good.

Also, if you narrow down a large amount to a degree, the material becomes a rigid body,
The cushioning effect will also be lost, which is undesirable.

Therefore, an object of the present invention is to provide a cassette tape using a planar separate sheet having island-like protrusions (dowels) that solves the above-mentioned drawbacks.

[Means for Solving the Problems] As a result of various studies, the present inventors have discovered that a second island-shaped protrusion ( It has been found that by forming dowels, the cushioning properties of the separate sheet can be improved, and thereby the tape can be wound in a uniform manner.

Hereinafter, the present invention will be described in detail with reference to the drawings. Figure 6 shows the separate sheet of the cassette tape of the water chamber embodiment, where (a) is a plan view and (b) is the A-A of (a).
It is an A' sectional view. FIG. 7 shows a cassette tape of the water chamber embodiment incorporating the above-mentioned separate sheet. Note that in these figures, parts common to parts in other drawings are indicated by the same reference symbols, and detailed explanations will be omitted.

Now, the separate sheet 1 of this embodiment has a plurality of trapezoidal or dome-shaped protrusions (dowels) 2 that protrude toward the tape 3 side.
In addition to having a window 5, a hole 10, etc., the side opposite to the dowel 2,
That is, it has a second protrusion (dowel) 6 that protrudes toward the cassette half 4 side. Dowel 6 is separate sheet 1
As long as they can provide cushioning properties, two or more of them may be used in the peripheral portion of the separate sheet at positions as shown in FIG. 6(a). Further, the dowel 6 may be located in the center of the separate sheet. In short, dowel 6 is dowel 2
It is sufficient to use an appropriate number experimentally, and can be easily determined by considering the overall effect. As shown in FIG. 6, the separate sheet 1 is held at a position floating from the half 4 by dowels 6, and the conventional dowels 2 come into contact with the tape winding surface, thereby ensuring a cushioning effect.

With this feature of the invention, the height of dowel 2 can be set equal to or lower than the conventional height, and the overall height of the two types of dowels can be distributed between dowels 2 and 6 or similarly - The effect is the same even if the dowel height is given as follows. In addition, as a quality effect, the dowel height was conventionally limited to 0.1 mm to 0.5 mm, but the upper limit of the dowel height has been doubled to 1.5 mm. It can be made up to 0.0 mm (dowel height 2 is 0.5 mm, dowel height 6 is 0.5 mm), and the effect in terms of design and quality is very large.

In the above embodiment, the number and position of dowels 2 and 6 are specified, but there may be a case where there are more dowels 6 than dowels 2, and the shape of dowels 2 and 6 may be different. There can also be various types.

These can be determined from design considerations such as tape winding torque.

4. tl l Figure 1 shows a conventional separate sheet, in which (a) is a plan view and (b) is a sectional view taken along line AA' in (a). FIG. 2 is a sectional view of a cassette tape using the separate sheet of FIG. 1. FIG. 3 is a cross-sectional view showing the process of forming a protrusion (dowel), with (a) before molding, (b) during molding, and (c) when the mold is opened. FIG. 4 is a perspective view of the deep drawing redowel.

Figure 5 shows a separate sheet with deep drawing dowels,
(a) is a plan view, and (b) is a sectional view taken along line BB' in (a). FIG. 6 shows a separate sheet according to an embodiment of the present invention, in which (a) is a plan view and (b) is a sectional view taken along line AA' in (a). FIG. 7 is a sectional view of a cassette tape incorporating the separate sheet of the above embodiment. The upper part of the figure is as follows.

1: Separate sheet 2: Protrusion (dowel) 3: Tape 4: Half case 6: Second protrusion (dowel) Figure 1 Figure 2 Figure 3 Figure 5

Claims (1)

[Claims] (1) A plurality of island-shaped protrusions protruding toward the tape side are formed by drawing on a planar separate sheet interposed between the tape and the half case, and a plurality of island-shaped protrusions protruding toward the half case side are formed by drawing. A method for manufacturing a separate sheet for cassette tapes, characterized by drawing and forming protrusions.