JPS6213264Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a magnetic tape cartridge featuring a transparent window, and is improved to prevent malfunctions when optically detecting the end of the magnetic tape.

In the video magnetic tape cartridge shown in FIG. 1, when it is loaded into the video unit, the through hole 1
The lamp 11 on the video unit side is inserted through the
The light from this lamp 11 passes through the transparent leader tape connected to both ends of the magnetic tape 3, and passes through the start sensor 12 and end sensor 1 on the video unit side.
The magnetic tape 3 reaches the phototransistor 3, which is used to detect the leading and trailing ends of the magnetic tape 3.

In reality, the leader tape has a light transmittance approximately 1000 times greater than that of the magnetic tape 3, and is set to prevent both sensors 12 and 13 from malfunctioning due to this large difference in light transmittance. Further, transparent windows 5, 5 provided on the left and right sides of the upper case 1a constituting the main body case 1 for visually checking the amount of tape winding are also arranged at positions away from the optical paths A, B of both sensors.

However, when strong light enters the main body case through the transparent window 5, the sensors 12 and 1
There was still a concern that the magnetic tape 3 would react and the running magnetic tape 3 would stop unexpectedly, causing a malfunction, and it was difficult to be certain. On the other hand, making the transparent window 5 smaller is inconvenient for viewing the amount of tape winding.

Therefore, this idea focuses on this fact,
The transparent window will be kept at a size that makes it easy to see the amount of tape wrapped as before. However, the side of the transparent window near the sensor optical path is partially formed with a semi-transparent matte surface to prevent strong light from entering the main body case from the outside. This is what we are trying to provide.

The details will be explained below based on the drawings.

FIG. 1 shows an example of a video magnetic tape cartridge, the main body case 1 of which is made up of upper and lower plastic cases 1a and 1b screwed together with lids, and a pair of tape reels 2 on the left and right inside.
a and 2b are rotatably mounted. The magnetic tape 3 is latched to both reels 2a and 2b via transparent leader tapes connected to both ends, and is fed out from one supply reel 2a to the front of the case and wound onto the other take-up reel 2b. A front cover 4 for covering and protecting the outside of the magnetic tape 3 when not in use is pivotally attached to the front surface of the main body case 1 so as to be openable and closable.

Transparent windows 5, 5 are provided on the left and right sides of the upper case 1a.
is provided, and the amount of tape wound on each tape reel can be seen from the outside through each transparent window 5. As shown in FIG. 2, each transparent window 5 has a window 6 transparently provided at the corresponding position of the upper case 1a, and a flat transparent plate 7 made of plastic is attached from the inside to the inner peripheral edge of the window 6. The structure is ultrasonically welded.

A through hole 10 is bored in the front central part of the bottom wall 9 of the case, and when a magnetic tape cartridge is loaded into the video unit, a lamp 11 of the video unit is inserted into the main body case through the hole 10. is inserted. Inside the main body case, there is a supply side sensor optical path A in which the light from the lamp 11 passes through the front of the left and right side walls of the main body case 1, exits the case, and reaches each phototransistor of the video start sensor 12 and end sensor 13. A take-up side sensor optical path B is configured. In other words, these two sensor optical paths A and B
is provided across the magnetic tape 3, and the light from the lamp 11 does not pass through the magnetic tape portion, but passes through the transparent tape portions at both ends, reaching each sensor 12, 13, and the light from the lamp 11 reaches the tip of the tape. and the end is detected. More specifically, the magnetic tape 3 is attached to one of the left and right tape reels 2a, 2b.
It is detected that the magnetic tape 3 has been completely wound up, and the magnetic tape 3 stops running and starts the next operation.

Now, in the present invention, in the magnetic tape cartridge of this basic form, the outer surface of the portion of the transparent plate 7 constituting each transparent window 5 closer to each sensor optical path, that is, the portion closer to the front in the figure, is made of semi-transparent material having minute irregularities. The matte surface 7a is integrally molded with plastic, and the amount of light incident from the outside into the main body case is suppressed by the matte surface 7a in the portion of the transparent plate 7 near the sensor optical path.

The matte surface 7a may be formed on the inner surface of the transparent plate 7, or the matte surface 7a itself can be formed by applying a matte paint to the transparent plate 7 or pasting a matte plastic film to the transparent plate 7. This can also be achieved by doing something like this.

In addition, in the illustrated example magnetic tape cartridge,
Furthermore, although the case 1a has transparent windows 5, 5 on the left and right sides, the present invention is also applicable to cases in which the transparent window 5 is provided on either the left or right sides or in the center of the upper case 1a. can. Furthermore, the sensor optical paths A and B may be provided only on either the left or right side, or in FIG. It may be inserted into

As explained above, according to this invention, the surface of the portion of the transparent plate 7 constituting the transparent window 5 near the sensor optical path is formed into a semi-transparent matte surface 7a. The transparent window 5 can suppress the amount of light transmitted inside the case as necessary and sufficient. Therefore, the transparent window 5 can be used to view the main body case from the outside while keeping the size convenient for viewing the amount of tape wound on the tape reel. It has now been possible to reliably prevent the tape end sensor from malfunctioning even if strong light enters the tape end sensor.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway plan view illustrating a magnetic tape cartridge according to the present invention, and FIG. 2 is a sectional view taken along the line CC in FIG. 1. 1...Main case, 1a...Upper case, 1b...
...Lower case, 2a, 2b...Tape reel, 3...
...magnetic tape, 5...transparent window, 6...window, 7...
...Transparent plate, 7a...Matte surface, 9...Case bottom wall, 10...Through hole, 11...Lamp, 12, 13
...Tape end sensor.

Claims (1)

[Scope of utility model registration request] Main body case 1 consisting of upper and lower cases 1a and 1b
A tape reel for winding a magnetic tape 3 with a transparent leader tape connected to both ends is installed inside the machine, and a transparent window 5 is formed in the upper case 1a to see the amount of tape wound on the tape reel. When loaded on the side, there is a light detection lamp 11 inside the main body case.
In a magnetic tape cartridge having a structure in which the end of the magnetic tape is detected by inserting the lamp 11 and the light from the lamp 11 passing through the transparent leader tape and reaching the tape end sensor on the machine side, a transparent window is inserted into the magnetic tape cartridge. A magnetic tape cartridge characterized in that the inner or outer surface of the portion of the transparent plate 7 near the sensor optical path forming the transparent plate 5 is formed into a semi-transparent matte surface 7a.