JP2000011599A - Magnetic tape cassette - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deformation of a screw boss provided on an upper half case constituting a magnetic tape cassette when molded as well as the deformation when screwing it with a lower half case. SOLUTION: An extending part is formed at a part of a hood part 61b formed on the upper half case 40, and the screw boss 2 for screwing the lower half case is integrally formed with the extending part. At this time, a gate to inject resin for molding the upper half case 40 is positioned near the back face side of the screw boss 2. Since the upper half case 40 is provided with a thick part which forms the flow passage of the resin to the screw boss at the time of molding, at the part confronted with the gate while connecting to the extending part, the flowability of the resin to the screw boss part 2 is improved and the proper resin pressure is secured, then the deformations of the screw boss 2 and its vicinity are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape cassette, and more particularly to a structure for reinforcing upper and lower half cases constituting a magnetic tape cassette.

[0002]

2. Description of the Related Art As is well known, various magnetic tape cassettes are used in video equipment such as video decks. Among them, a relatively small one is, for example, a digital video cassette (DVC). Hereinafter, FIGS. 4 and 5
An example of a magnetic tape cassette known as DVC will be described with reference to FIG. First, the configuration of a conventional magnetic tape cassette 30 will be described with reference to FIG. 4. A lower half case (hereinafter, referred to as a lower half) 31 includes a pair of reels 32.
a, 32b are rotatably arranged, and both reels 32a, 3
A magnetic tape (not shown) is wound around 2b. The magnetic tape is guided by tape guides 33a and 33b on the left and right sides at the front end of the cassette, and passes through the opening 34 on the front end side of the lower half 31. And
Teeth 35a, 35b are formed on the entire periphery of the reels 32a, 32b (the periphery of the lower flange).

On the other hand, when the magnetic tape cassette 30 is not loaded in a video deck (not shown), that is, when the cassette is stored or carried, the magnetic tape is prevented from being loosened on the rear side of the cassette. Reel 32
a, 32b, the space 3 formed between the reel 3
Brake member 38 provided with locking claws 37a, 37b constituting a locking device for locking the rotation of 2a, 32b
And a compression spring (brake spring) 39 for urging the brake member 38.

[0004] An upper half case (hereinafter, referred to as an upper half) 40 includes an outer lid 41 constituting a lid for covering an opening at a front end of a lower half 31, and an upper lid 4.
2 and the inner lid 43 are attached so as to be freely opened and closed. A lid lock claw 45 is protruded from the inner side surface of the both side plates 44 of the outer lid 41. Inside the left and right side plate portions 46 of the lower half 31, a frame-shaped storage portion 51 for rotatably attaching a lid lock 47 locked to a lid lock claw 45 of the outer lid 41.
Is provided. A spring 48 for urging the lid lock 47 toward the lock side is attached to the rear of the storage portion 51. This attachment is performed by attaching an annular portion formed at the end of the spring 48 to the rod-shaped locking pin 52. It is performed by Note that the configuration of the storage section 51 and the storage mode of the lid lock 47 are left-right symmetrical. Therefore, FIG. In the figure, the members other than the main part are not denoted by the reference numerals, and the description is omitted.

[0005] On both sides of the front end of the upper half 40, eaves 61a and 61b defining an opening for tape withdrawal are formed, and overhangs 62a and 62b are provided at a part of the tip. . Under the overhang portions 62a, 62b, a screw boss (boss for screwing a screw) 63 is directed downward, that is, toward the lower half 31 in the state of FIG.
a and 63b are provided. This screw boss 63a, 6
Reference numeral 3b is used when the upper half 40 and the lower half 31 are screwed together with one another, and regulates the space between the upper and lower half cases at the opening.

Next, the configuration of the screw bosses 63a and 63b will be described with reference to FIGS. Since the screw bosses 63a and 63b have the same configuration, only one of the screw bosses 63b will be described. FIG. 5 is a perspective view showing the vicinity of the screw boss 63b with the upper half 40 turned upside down, and FIG. 6 is a sectional view of a main part showing the configuration of the screw boss 63b. Eave portion 61b from upper half 40 via inclined portion Xa
Is formed, and the overhang portion 6 having the inclined portion Ya, the flat plate portion Yb, and the inclined portion Yc so as to project from a part of the eave portion 61b.
2b are integrally formed. Then, a cylindrical screw boss 63b is formed so as to hang over the flat plate portion Yb and a part of the inclined portion Yc, and the side surface of the screw boss 63b and the flat plate portion Y
b, the inclined portion Ya, and the eaves portion 61b are formed with reinforcing ribs 64. In the vicinity of the reinforcing rib 64, a slight raised portion 65 is formed apart from the reinforcing rib 64, and is formed in a portion facing the gate with the molding of the upper half 40. .

Hereinafter, molding of the upper half 40 will be described. The upper half 40 is molded by injecting a resin from a gate (both not shown) provided in a mold. The gate is formed at a position corresponding to the rear side of the raised portion 65, and the resin injected from the gate is filled in the space in the mold to form the upper half 40. Remains. 5 and 6 show a state in which the upper half 40 is turned upside down, so that two gate marks B appear on the front side in the state shown in FIG. However, when the magnetic tape cassette 30 is not used, the gate mark B is covered with the outer lid 42, so that the user does not normally see it.

[0008]

However, the magnetic tape cassette 30 having the above configuration has various problems as described below. That is, when assembling the magnetic tape cassette 30, the lower half 31 and the upper half 40 are overlapped and screwed. This screwing is performed at a plurality of locations. One of the locations will be described. A screw 68 is inserted through an insertion hole (not shown) formed in the lower half 30 as shown in the lower left end of FIG. The screw boss 63a is shaped like a hollow cylinder. No screw groove is formed in the screw boss 63a, and the screw boss 63a is screwed and tightened with the rotation of the screw 68. Therefore, screw 68
When the screw boss 63a rotates, a large force is applied to the screw boss 63a.
In order to prevent the deformation of b, the reinforcing rib 64 is provided.

The reinforcing ribs 64 are provided with screw bosses 63a, 63b.
It is desirable to form it at the same height as the above or to make it thicker to improve the strength. However, the above-mentioned measures for improving the strength of the reinforcing ribs 64 are limited in relation to the lower half 31, so that the height and thickness cannot be sufficiently obtained, and are not sufficient from the viewpoint of preventing deformation of the screw bosses 63 a and 63 b. . Further, since the gate position is separated from the screw bosses 63a and 63b and the reinforcing ribs 64, the resin has poor fluidity during molding, the resin is not filled into the screw bosses 63a and 63b with an appropriate pressure, and the screw bosses 63a and 63b are deformed. There was also a problem such as molding with.

An object of the present invention is to provide a magnetic tape cassette configured to improve the production yield by preventing deformation of upper and lower half cases screwed when assembling the magnetic tape cassette.

[0011]

According to the present invention, there is provided an upper and lower half case which is screwed and fixed in an overlapped state, and a magnetic tape rotatably housed in the upper and lower half case. A pair of reels, a lid that closes an opening formed at one end of the upper and lower half cases and is opened when the magnetic tape is pulled out from the opening, and projects from the upper half case toward the opening. A screw boss that is formed on a protruding portion that protrudes further from the eaves portion and that screws with the screw when fixing the upper and lower half cases with screws, and that regulates the distance between the upper and lower half cases at the opening. A magnetic tape cassette that forms the upper half case by positioning a gate for resin injection near the back side of the screw boss; Continuously Sulfur butterfly out portion, the flow path and becomes thick portion of the resin into the screw boss portions during molding, it is achieved by a magnetic tape cassette characterized by having the opposed portion to the gate.

The magnetic tape cassette has an upper half case formed by providing a gate for injecting resin near the screw boss. Further, since the thick portion is formed continuously to the overhang portion where the screw boss is formed, an appropriate resin flow rate after passing through the gate is secured during injection molding, and a decrease in the resin temperature is prevented. Therefore, the flow resistance is reduced. Therefore, the fluidity of the resin to the screw boss is improved, and the proper resin pressure is secured, so that the screw boss is not deformed. In addition, since the rigidity of the screw boss and the eaves portion on which the screw boss is formed is increased by this thick portion, deformation near the screw boss when the upper and lower half cases are screwed can be prevented. The thickness of the thick portion is preferably equal to or larger than the gate diameter, and the larger the thickness, the more preferable. For example, when the gate diameter is 0.8 mm, the thickness of the thick portion is preferably 0.8 mm or more. The screw boss and the thick portion may be connected via a rib or the like.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a magnetic tape cassette according to the present invention will be described with reference to the drawings. FIG. 1 is an enlarged perspective view of a main part showing a configuration of a screw boss provided in an upper half according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view of a main part showing a configuration of a screw boss and a flow of resin. In the description of the present embodiment, reference numerals given to the magnetic tape cassette shown in FIG. 4 and each member shown in FIGS. 5 and 6 are appropriately used.

The screw boss reinforcing mechanism 1 shown in FIG. 1 is provided at both ends on the front side of the upper half 40 as in the conventional example. The configuration other than the screw boss reinforcing mechanism 1 described below is the same as the conventional example. One of them will be described as in FIG. FIG. 1 is a perspective view showing the configuration of the screw boss strengthening mechanism 1 with the upper half 40 turned upside down. An eave portion 61b is formed from the upper half 40 via an inclined portion Xa, and projects from a part of the eave portion 61b. The projecting portion 62 having the inclined portion Ya, the flat plate portion Yb, and the inclined portion Yc.
b is formed integrally. Then, a hollow cylindrical screw boss 2 is formed so as to hang over a part of the flat plate portion Yb and the inclined portion Yc. However, in the present embodiment, the reinforcing rib 64 is not formed, and the thick portion 3 having a truncated cone shape is formed so as to extend from the eave portion 61b to the inclined portion Ya.

That is, the screw boss strengthening mechanism 1 according to the present embodiment includes an eave portion 61b having the same shape as the conventional example, an overhang portion 62b projecting from a part of the eave portion 61b, and having the same shape as the conventional example. It is provided with a screw boss 2 formed as a stand alone in the projecting portion 62b and a thick portion 3. As is clear from FIG. 2, the thick portion 3 extends from the eave portion 61b to the middle of the inclined portion Ya, and the center of the back surface of the thick portion 3 is a gate position for injecting resin.

When the upper half 40 is molded, the resin is formed as shown in FIG.
As shown by an arrow C, the upper half 40 is circulated along the surface of the die, in other words, the space inside the die along the surface of the upper half 40 and gradually fills the space. Incidentally, at the time of molding, the side surface on which the gate mark B is formed becomes the upper part. By bringing the gate closer to the inclined portion Ya, that is, closer to the screw boss 2, the space between the gate and the space where the screw boss 2 is formed is reduced, and the fluidity of the resin is improved. In addition, by forming a space that becomes the thick portion 3 at the position of the gate, the injected resin does not abruptly diverge from the injection position, and is diverted after it temporarily accumulates in the space that becomes the thick portion 3. Therefore, the fluidity is improved and an appropriate resin pressure is ensured. Therefore,
The deformation factor of the screw boss 2 relating to the fluidity of the resin is eliminated by forming the space for forming the thick portion 3.

On the other hand, in the state where the upper half 40 is molded, the thick portion 3 is formed so as to straddle a part of the eave part 61b and a part of the inclined part Ya constituting the overhang part 62b. You. This is because the eaves 61b and the overhang 62b are
Means partially reinforced by Therefore, the eaves portion 61b and the overhang portion 62b are firmly integrated,
When the screw is screwed by overlapping with the lower cassette 31 as described above, even if a force that twists the screw boss 2 is applied, the projecting portion 62b is not bent and deformed by this force, and the deformation of the screw boss 2 is also prevented. Is prevented.

As described above, the upper half 40 shown in the first embodiment can prevent the deformation of the screw boss during molding with resin, and can prevent the deformation due to screwing of the screw when assembling as a magnetic tape cassette after molding. Can also be prevented. Therefore, in the magnetic tape cassette to which the upper half 40 is applied, the defect rate in the manufacturing process is reduced, the manufacturing yield is improved, and the reliability is improved. In addition, a mold is used for molding the upper half, but it is only necessary to change a part when manufacturing the mold,
Manufacturing costs can be reduced. FIG. 3 is a perspective view of a second embodiment of the present invention. In the second embodiment, the thick portion is provided continuously with the reinforcing rib provided on the screw boss. That is, the thick portion is provided continuously to the overhang portion via the reinforcing rib. According to this configuration, the resin injected into the thick portion at the time of molding flows well through the rib to the screw boss, and the resin is filled in the screw boss with an appropriate amount at an appropriate pressure.

Although the embodiment of the present invention has been described above, the thick portion in the present invention may be formed directly or indirectly continuously from the overhang portion on which the screw boss is formed. Also,
The magnetic tape cassette to which the present invention can be applied is not limited to DVC, but the present invention can also be applied to a normal VHS type magnetic tape cassette and the like.

[0020]

As described above, in the magnetic tape cassette according to the present invention, when the upper and lower half cases are screwed together, the flow of the resin to the screw boss portion at the time of molding is continuous with the projecting portion provided with the screw boss. A thick portion serving as a path is provided at a portion facing the gate. According to this configuration, the fluidity of the resin is improved and an appropriate resin pressure is ensured, so that deformation of the screw boss can be prevented. In addition, the thick portion improves the strength of the overhanging portion on which the screw boss is formed and the eaves portion integrally formed with the overhanging portion. Therefore, it is possible to prevent deformation when the upper and lower half cases are screwed, thereby preventing deformation of the upper half case itself and reducing the defect rate of the magnetic tape cassette.

[Brief description of the drawings]

FIG. 1 is an enlarged perspective view of a main part showing a configuration of a first embodiment of a magnetic tape cassette according to the present invention.

FIG. 2 is a cross-sectional view of a main part showing the configuration of the main part of the upper half cassette and the flow of resin.

FIG. 3 is an enlarged perspective view of a main part showing a configuration of a second embodiment of the present invention.

FIG. 4 is an exploded perspective view of members showing an example of a conventional magnetic tape cassette.

FIG. 5 is an enlarged perspective view of a main part showing a configuration of a conventional upper half cassette.

FIG. 6 is a cross-sectional view of a main part showing the configuration of the main part of a conventional upper half cassette and the flow of resin.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 screw boss strengthening mechanism 2 screw boss 3 thick portion 30 magnetic tape cassette 31 lower half case 32 a, 32 b reel 40 upper half case 41 outer lid 61 a, 61 b eave portion 62 a, 62 b overhang portion B gate mark C resin flow direction Xa, Ya, Yc Inclined part Yb Flat part

Claims (1)

[Claims] An upper and lower half case fixed by screws in a superposed state, and a pair of reels around which a magnetic tape rotatably housed in the upper and lower half cases is wound;
A lid that closes an opening formed at one end of the upper and lower half cases and is opened when the magnetic tape is pulled out from the opening, and further extends from an eave portion that protrudes from the upper half case toward the opening. A screw boss formed on the overhanging portion, screwed with the screw when fixing the upper and lower half cases with screws, and regulating a distance between the upper and lower half cases at the opening. In a magnetic tape cassette that forms the upper half case by positioning a gate for resin injection near the side, the upper half case is continuous with the overhang portion, and a resin flow path to the screw boss portion during molding. A magnetic tape cassette having a thick portion at a portion facing the gate.