GB2089318A

GB2089318A - Magnetic tape cassettes; mountings for pressure pads

Info

Publication number: GB2089318A
Application number: GB8135193A
Authority: GB
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 1980-12-09
Filing date: 1981-11-23
Publication date: 1982-06-23
Also published as: DE3148352A1; JPS5798590U; ATA501281A; GB2089318B; JPS6230225Y2; AT373430B; FR2495812A1

Abstract

A tape cassette of the type in which magnetic heads are inserted into a cassette case 12 accommodating a magnetic tape 11 through two windows 13A, 13B formed in the case 2, has pad support springs 15A, 15B supporting pads 14A, 14B for urging the respective magnetic heads against the magnetic tape 11. The springs 15A, 15B are mounted in the case 12 independently of each other between tape guide pins 16A, 16B, 17A, 17B provided at the opposite ends of each window 13A, 13B in the tape transport direction. Each spring may have its ends provided with different shaped portions 15b and 15a, and each pad may be positioned at an asymmetric position on the spring with the shorter spring portion being of smaller width b than the width a of the larger spring portion. <IMAGE>

Description

SPECIFICATION Magnetic tape cassettes This invention relates to magnetic tape cassettes.

In the known small type of magnetic tape cassette called a 'microcassette', a cassette case 2, as shown in Fig. 1 of the accompanying drawings, accommodates a magnetic tape 1. The cassette has two windows 3A and 3B, and a pad structure having pads 4A and 4B provided at the centres of respective windows 3A and 3B are secured to a single leaf spring 5, the leaf spring 5 being centrally supported by a support member 6. The cassette also has tape guide pins 7, engagement members 8 engaged by the free ends of the leaf spring 5, and a capstan insertion hole 9.

Because the pads 4A and 4B are secured to the cantilever-supported leaf spring 5, it is difficult to get the pads 4A and 4B to exert uniform pressure. In addition, if pressure is applied to one of the pads 4A or 4B, the other pad 4B or 4A is affected by that pressure, so the pad pressures depend on whether only a single magnetic head is used or two magnetic heads are used. Moreover, because one of the pads 4A or 4B is in frictional contact with the tape 1 running from the side of the free end of the leaf spring 5 to the support point side thereof, the pad pressure is subject to fluctuations due to changes in and vibrations of the leaf spring 5. Moreover, it is necessary to bend the leaf spring 5 into a complicated shape to obtain a required uniform pad pressure.

According to the present invention there is provided a tape cassette of the type in which magnetic heads are inserted into a cassette case accommodating a magnetic tape through two windows formed in the case, wherein pad support springs supporting pads for urging the respective magnetic heads against the magnetic tape are mounted in the case independently of each other between tape guide pins provided at the opposite ends of each said window in the tape transport direction.

The invention will now be described by example with reference to the accompanying drawings, in which: Figure 1 is a fragrnenitary plan view showing a known tape cassette; Figure 2 is a fragmentary plan view show ing an embodiment of tape cassette according to the invention; Figures 3 and 4 are respectively a fragmentary exploded perspective view and a sectional view showing a pad support spring mounting structure in the embodiment; Figure 5 is a sectional view showing a different example of the pad support spring mounting structure; and Figure 6 is a perspective view showing a specific example of the shape of the pad support spring used for the embodiment.

Referring to Fig. 2, the embodiment to be described is a so-called microcassette comprising a cassette case 12 accommodating a magnetic tape 11. The cassette has two windows 1 3A and 1 3B, formed in the transport direction of the magnetic tape 11 and through which magnetic heads (not shown) may be inserted.

At the windows 13A and 1 3B, pad support springs 1 5A and 1 SB, having at their respective intermediate portions in the longitudinal direction pads 1 4A and 1 4B for urging the magnetic tape 11 against the inserted magnetic heads with a predtermined pressure, are mounted independently. The pad support springs 1 SA and 1 SB are formed by respective leaf springs, which are independently supported by guide pins 16A, 17A, 16B and 1 7B provided at the opposite ends of the windows 1 3A and 1 3B in the tape transport direction.

In this embodiment, to provide an opposite end support structure for the pad support spring 1 5, as shown in the fragmentary exploded perspective view of Fib. 3, tape guide pins 1 6 and 17 projecting from a base half 1 2A forming the cassette case 12 are formed with respective notches 1 6a and 1 7a, which are formed with slits 1 6b and 1 7b through which the pad support spring 1 5 is inserted.

Also, retaining ribs 1 2a are provided on a cover half 1 21S at positions thereof corresponding to the notches 1 6a and 1 7a of the tape guide pins 1 6 and 17. When the base half 1 2A is mounted on the cover half 1 2B, the pad support spring 1 5 is brought into engagement with the tape guide pins 16 and 17 as shown in the sectional view of Fig. 4.

The retaining rib 1 2a and notch 1 6a of the tape guide pine 16 have respective inclined surfaces 1 2c and 1 6c which serve as guides for positioning when the cover half 1 2B is mounted on the base half 1 2A.

As shown in the sectional view of Fig. 5, the guide pin 16 may be formed with a substantially V-shaped sectional profile notch 1 sal, and the cover half 1 2B may be formed with a retaining rib 1 2a' having a complementary shape to the notch 1 Era. The notches 1 6a and 1 7a are formed on portions of the guide pins 16 and 17 which do not touch the magnetic tape 11.

In a standard microcassette, the magnetic head is inserted at a position displaced from the centre of the window 1 3A or 1 3B of the cassette case 12, that is from a position of 1/2 where 1 is the distance between the guide pins 1 6 and 17. Therefore, in the embodiment the pad 14 is provided on the pad support spring 15 at an asymmetric position thereof.

In the embodiment, as shown in Fig. 6, the long side dimension a of the pad support spring 1 5 is made larger than the short side dimension b to provide for elastic deformation of the pad support spring 15 with good balance. In addition, the portions a and b of the pad support spring 1 5 are made to have different dimensions, and also the opposite ends 1 5a and 1 5b are made to have different shapes, thus permitting simple visual judgement as to whether the pad support spring 15, which carries the asymmetrically installed pad 14, is correctly mounted in the cassette case 12.

Thus the tape cassette has a construction in which the magnetic heads can be inserted into the cassette case accommodating the magnetic tape through two windows formed in the case, and pad support springs supporting pads for urging the tape against the magnetic heads are independently mounted between tape guide pins provided at the opposite ends of each window in the tape transport direction. Since the individual pad support springs are independently supported by the opposite end support structure, uniform pressure can be exerted on the magnetic tape by the pads. Also, there is no possibility of interference between the pads, and also there is no fluctuation of the pad pressure in the tape transport direction. Thus, it is possible to provide a tape cassette, in which the magnetic heads can be urged against the magnetic tape with a steady and stable pad pressure.

Claims

1. A tape cassette of the type in which magnetic heads are inserted into a cassette case accommodating a magnetic tape through two windows formed in the case, wherein pad support springs supporting pads for urging the respective magnetic heads against the magnetic tape are mounted in the case independently of each other between tape guide pins provided at the opposite ends of each said window in the tape transport direction.

2. A tape cassette according to clailm 1 wherein each said pad support spring has opposite ends provided with engagement portions of different shape, and each pad is installed on the associated pad support spring at a position displaced from the longitudinal centre position of the pad support spring.

3. A tape cassette according to claim 2 wherein each said pad support spring comprises a leaf spring, which has a smaller width for its shorter portion extending in one direction from the position of installation of the pad displaced from its longitudinal centre position than for its longer portion extending in the opposite direction.

4. A tape cassette substantially as hereinbefore described with reference to Figs. 2 to 6 of the accompanying drawings.