JPH0462432B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fastening structure between an upper case and a lower case of a magnetic tape cartridge, which includes a cartridge case consisting of an upper case and a lower case.

In FIG. 1, reference numeral 1 denotes a cartridge case, and in its hollow part, although not shown, a magnetic tape, a pair of reels, a magnetic shield plate, a plate spring to which a pad is fixed, etc. are arranged at predetermined locations. As shown in FIG. 2, the cartridge case 1 is made up of an upper case 2 and a lower case 3 stacked on top of each other, and both cases 2 and 3 are fastened together with screws 4.

FIG. 2 is a diagram showing a conventional fastening structure between the upper case 2 and the lower case 3. A boss hole 5 is provided on the lower surface of the upper case 2, and a boss portion 6 is provided on the upper surface of the lower case 3 at a position corresponding to the boss hole 5. Also, there are screws 4 on the top of the upper case 2.
A large diameter depression 8 is provided to accommodate the head 7 of the bus, and a through hole 9 for screw insertion is formed from the depression 8 toward the bus hole 5. On the other hand, the boss portion 6 of the lower case 3 is provided with a screw insertion recess 10 corresponding to the through hole 9, and by inserting the screw 4 from the through hole 9 to the recess 10,
Upper case 2 and lower case 3 are fastened together via screws 4.

FIG. 3 is a front view of a screw 4a conventionally used to fasten the upper case 2 and lower case 3.
This screw 4a is the same as a commonly used screw, and the screw thread 11a has a first inclined surface 12a inclined toward the tip of the screw 4a, and a second inclined surface 12a inclined toward the head 7 side. It has an inclined surface 13a.

Conventionally, after placing the recess 10 under the through hole 9 where the upper case 2 and the lower case 3 are overlapped, the screw 4a is inserted through the through hole 9 while rotating, and the screw 4 is inserted into the through hole 9 while rotating.
The upper case 2 and the lower case 3 were integrally fastened by screwing the head 7 into the outer circumference of the recess 10, that is, the boss 6, and by bringing the head 7 into contact with the bottom of the recess 8.

By the way, in the conventional method of inserting the screw 4 while rotating, the outer periphery (boss part 6) of the recess 10 is scraped and chips are generated, which are sequentially inserted into the recess 8 by the rotation of the screw 4a. It is sent to the side and placed in the cartridge case. If the chips adhere to the magnetic tape or enter between the reel and the cartridge case 1, recording and reproducing characteristics will be affected. In addition, in the method of fastening the upper case 2 and lower case 3 by inserting the screws 4, if the screws 4 are turned too much, the screws become loose, and the fastening of the upper and lower cases 2 and 3 becomes uncertain. Become. An assembly method has been proposed that eliminates the drawbacks of the prior art and has high work efficiency without the generation of chips or loose screws that would impede the recording/reproducing characteristics.

A specific example of this proposed assembly method will be explained using FIGS. 4 to 8.

The thread 11b of the fastening screw 4b driven into the cartridge case 1 is the screw 4 shown in FIG.
It has a different shape from the thread 11a of a. That is, the screw thread 11b has a first inclined surface 12b inclined toward the distal end side of the screw 4b, and a flat surface 14b facing the seat surface of the head 7b.

The upper case 2 and the lower case 3 are molded from a synthetic resin having a predetermined elasticity, such as polystyrene resin. At predetermined locations on the upper case 2, that is, at the four corners and the center of the front side as shown in FIG.
As before, there are a boss hole 5, a recess 8, and a through hole 9 for insertion.
are provided for each. Further, a boss portion 6 and an insertion recess 10 are formed in the lower case 3 at positions corresponding to the boss hole 5 and the through hole 9 of the upper case 2, respectively. Note that the planar shape of the recess 10 is designed to be an appropriate shape such as a circle, a quadrangle, a polygon, or an ellipse.

As shown in Figure 4, upper case 2 and lower case 3
After the boss part 6 is fitted into the boss hole 5 by overlapping the boss part 6 and the recess part 10 is arranged below the through hole 9, the fastening screw 4b is inserted through the through hole 9 and the recess part 1 is inserted.
Hit towards 0. Since the upper and lower cases 2 and 3 have appropriate elasticity, the screw 4b is driven into the recess 10, and when the head 7b of the screw 4b comes into contact with the bottom of the recess 8 in the upper case 2, the screw 4b is driven in. (See Figure 6). When the screw 4b is driven in this way, as shown in FIG. The upper case 2 and lower case 3 are integrally connected.

When separating the upper case 2 and the lower case 3 as necessary, they can be removed by rotating the screws 4b in the loosening direction as in the conventional case.

This assembly method works even if the outer periphery of the recess is scraped by the thread when driving the screw.
Because it is pushed deep into the recess along with the screw,
Although it has the advantage of completely eliminating the possibility of shavings entering the cartridge case, it is not without its drawbacks.

That is, what is important in fastening the upper and lower cases 2 and 3 of the magnetic tape cartridge is that they are in sufficient contact with each other.

By the way, in the aforementioned assembly method, even if the screws 4b are press-fitted with enough force to bring the upper case 2 and lower case 3 into close contact with each other as shown in FIG. 6, when that force is removed, the elasticity of the lower case 3 As shown in FIG. 7, the screw 4b springs back and floats up.
As a result, the head 7b of the screw 4b separates from the upper case 2, which prevents the upper case 2 and lower case 3 from coming into close contact, which not only reduces the product value but also allows dust to enter the cartridge case 1. The recording and reproducing characteristics may deteriorate, and since the magnetic shield plate is sandwiched between the upper case 2 and the lower case 3, if the upper and lower cases 2 and 3 are not in close contact with each other, the magnetic shielding plate may deteriorate. The board will fall over and will no longer perform its function.

In order to eliminate this inconvenience, after driving the screw 4b, it is necessary to tighten the screw 4b by approximately 1/4 to 1/6 turn as shown in FIG. The addition of such a retightening process deteriorates work efficiency and brings about the drawbacks of conventional tightening methods again, which is not preferable.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic tape cartridge in which the upper and lower cases are in close contact with each other without requiring such additional tightening.

In order to achieve this object, the present invention provides an upper case that is molded from an elastic synthetic resin and has through holes for screw insertion at predetermined locations, and screws inserted at positions corresponding to the through holes of the upper case. a lower case molded from a synthetic resin having elasticity, and the recess is positioned below the through hole;
After that, the upper case and the lower case are connected by driving a fastening screw through the through hole of the upper case and using the elasticity of the lower case to make the thread of the fastening screw bite into the outer periphery of the recess. In the magnetic tape cartridge, a chevron-shaped elastic piece with its center facing upward is formed around the through hole of the upper case, and the elastic piece is elastically attached to the head bearing surface of the fastening screw. It is characterized by having come into contact with

Next, an embodiment of the present invention will be described using FIGS. 9 to 11.

The upper case 2b and the lower case 3 are molded from a synthetic resin having a predetermined elasticity, such as polystyrene resin. A boss hole 5, a depression 8b, and a through hole 9b for insertion are provided at predetermined positions of the upper case 2, and the peripheral portion 16 of the through hole 9b is formed into a chevron shape with the center portion facing upward. It forms an elastic piece. On the other hand, the lower case 3 has the upper case 2b
A boss portion 6 and an insertion recess 10 are formed at positions facing the boss hole 5 and the through hole 9b, respectively.

By overlapping the upper case 2b and the lower case 3, the boss portion 6 is fitted into the boss hole 5, and the recess 10 is disposed below the through hole 9b. In this state, as shown in FIG.
A truncated conical gap 15 is formed between and the recess 10.

The thread 11b of the fastening screw 4b that is driven into the cartridge case 1 has a first inclined surface 12b inclined toward the tip end of the screw 4, and a head 7b.
It has a seat surface 17 and a flat surface 14b facing the same.

This screw 4b is inserted through the through hole 9b and is strongly driven into the small diameter recess 10. Since the upper and lower cases 2 and 3 have moderate elasticity, the screw 4b
is forcibly driven into the recess 10, and the peripheral portion 16 is pressed by the bearing surface 17 of the screw head 7b, so that the entire screw is pressed and deformed into a substantially horizontal state as shown in FIG. Then, the screw thread 11b is in the recess 1.
It firmly bites into the periphery of 0.

When the pressure on the screw 4b is removed, the lower case 3
Due to the elasticity of the screw 4b, the screw 4b springs back and floats up. At the same time, the central part of the peripheral part 16 (elastic piece) rises slightly due to the elastic restoring force, and comes into elastic contact with the seat surface 17 of the screw head 7b (11th
figure). By elastically supporting the seat surface of the head 7b by the peripheral portion 16 in this manner, the upper case 2b is brought into close contact with the lower case 3 sufficiently without wobbling.

The height of the truncated conical gap 15 depends on various conditions such as the materials of the upper case 2b and lower case 3, the design of the peripheral part 16 and the boss part 6, the pitch of the screw thread 11b, and the fitting length of the screw 4b. In this way, the upper case 2b and the lower case 3 are set to have a close contact force.

As described above, the present invention fastens the upper and lower cases by driving screws, so no chips are generated. In addition, even if the outer periphery of the recess is scraped by the thread when driving the screw,
Because it is pushed deep into the recess along with the screw,
No shavings enter the cartridge case. In addition, the springback of the screw, which was a fatal flaw in conventional fastening methods, can be absorbed by the elastic piece coming into elastic contact with the bearing surface of the fastening screw head, eliminating the need for retightening and tightening the screw. No screw-up caused by over-turning. Because of this, the upper and lower cases can be securely fastened, and the recording and playback characteristics will not be affected by chips, etc. Moreover, the time required to fasten the upper and lower cases is shortened, improving work efficiency. can be achieved.

[Brief explanation of the drawing]

Figure 1 is a plan view of a conventional magnetic tape cartridge, Figure 2 is an enlarged sectional view taken along the line A-A in Figure 1, Figure 3 is a front view of a conventional fastening screw, and Figure 4. , Fig. 5, Fig. 6, Fig. 7, and Fig. 8.
The figure is an enlarged cross-sectional view of essential parts for explaining an improved method of assembling a magnetic tape cartridge, and FIGS. 9, 10, and 11 show an upper case of a magnetic tape cartridge according to an embodiment of the present invention. FIG. 6 is an enlarged cross-sectional view of main parts for explaining the fastening order of the lower case. 1...Cartridge case, 2b...Upper case, 3...Lower case, 4b...Screw, 5...Boss hole, 6...Boss portion, 9b...Through hole for screw insertion, 1
0...Concavity for screw insertion, 11b...Screw thread, 15
... Conical gap, 16 ... Periphery, 17 ... Seat surface.

Claims (1)

[Claims] 1. An upper case molded from an elastic synthetic resin with through holes for screw insertion at predetermined locations, and an elastic synthetic resin with recesses for screw insertion at positions corresponding to the through holes of the upper case. A lower case molded from the above is placed one on top of the other, the recess is positioned below the through hole, and then a fastening screw is driven through the through hole of the upper case, and the fastening screw is inserted using the elasticity of the lower case. In the magnetic tape cartridge that connects the upper case and the lower case, by inserting the screw threads into the outer periphery of the recess, the center part of the magnetic tape cartridge is attached to the periphery of the through hole of the upper case so that the central part thereof faces upward. A magnetic tape cartridge characterized in that a chevron-shaped elastic piece is formed and the elastic piece is brought into elastic contact with the head bearing surface of the fastening screw.