JP2001256758A - Magnetic tape cassette - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic tape cassette which generates no erroneous detection of a leader tape even when a half case has translucency. SOLUTION: In the magnetic tape cassette which houses a magnetic tape so as to be able to travel in the half case having the translucency, a shading wall 32 is provided in front of a light incident part 18a and a light emitting part 18b of a prism 18 for detecting a tape provided in the upper half case 4.

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 in which a magnetic tape is accommodated in a half case having a light transmitting property.

[0002]

2. Description of the Related Art DDS type, DAT type, VHS type, beta type, and DV type magnetic tape cassettes in which a magnetic tape is accommodated in a half case so as to be able to run are provided.
There are many types such as C type. In recent years, VHS
As a type of magnetic tape cassette, a transparent type in which a half case has a light-transmitting property and the inside can be visually recognized through the half case is known.

[0003]

The above magnetic tape cassette is configured to detect a tape end by detecting a transparent leader tape in a recording / reproducing apparatus.
In the recording / reproducing apparatus, an optical sensor is used to detect a leader tape.

For example, for a magnetic tape cassette of DDS type or DAT type, a light source and a light receiving sensor disposed near the front side on both sides of the cassette are used. On the other hand, the half case of the DDS type or DAT type magnetic tape cassette has a prism for guiding the light emitted from the light source to the back side of the magnetic tape and guiding the light from the back side of the magnetic tape toward the light receiving sensor. Is provided.

If the half case of a DDS type or DAT type magnetic tape cassette has translucency, in a recording / reproducing apparatus or the like, the light for tape detection is irregularly reflected by the half case or the like near the prism, or the half case is used. Light may be reflected or refracted in a resin such as a case, and light may enter from outside a predetermined direction other than the light incident portion of the prism. When light incident on the prism from outside the predetermined direction reaches the light receiving sensor from the light emitting portion, erroneous detection of the leader tape occurs, and it becomes impossible to accurately control the tape running.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems. Even if the half case has a light-transmitting property,
An object of the present invention is to provide a magnetic tape cassette that does not cause erroneous detection of a leader tape.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic tape cassette in which a magnetic tape is movably accommodated in a translucent half case. This is achieved by a magnetic tape cassette characterized in that the periphery of the light transmitting means has a light-shielding structure that does not impair the tape detecting function.

In the present invention, the light-shielding structure may be applied to at least a portion of the light transmitting means other than the light entrance and the light exit. Preferably, a light-shielding structure is applied to the entire periphery of the light transmitting means except for the light incident part and the light emitting part of the light transmitting means.

As a light-shielding structure, for example, a light-shielding member is provided, a light-shielding liquid is applied, printing is performed with light-shielding ink, a light-shielding substance is mixed in a molding resin, and fine irregularities are formed on the surface of the light-shielding portion. Forming (texturing) or forming streaks causes refraction or scattering.

In the present invention, having translucency means that the inside of the half case can be visually seen through, and specifically, at least visible light (having a wavelength of 380 nm to 380 nm) with respect to the half case having a thickness of 1 mm. 780 nm light)
Is 0.5% or more.

Further, when infrared light is used as the tape detection light, infrared light (light having a wavelength of 780 nm to 950 nm) and visible light (light having a wavelength of 380 nm to 780 nm) are applied to a half case having a thickness of 1 mm. ) Is 0.5% each
Above means transmission. Such a half case may be either a chromatic color or an achromatic color.

Further, in the present invention, the light shielding refers to light used for a tape detecting means in a recording / reproducing apparatus or the like. Specifically, the light is blocked so that the amount of infrared light or visible light reaching the light receiving sensor from the tape detection light source used for the tape detection means in the recording / reproducing device or the like is less than the detection threshold. Means that. Also,
The form of light shielding may be any of absorption, reflection, refraction, scattering and the like.

As the light transmitting member, DDS type and D
In the case of the AT type magnetic tape cassette, it is a prism, and in the case of the DVC type, VHS type, and beta type, it is an optical path defined in a half case. In the case of the DDS type and the DAT type, a light-shielding structure is provided on the peripheral surface of the prism except for the light-entering portion and the light-emitting portion, and near the periphery of the prism except for the light-entering portion and the light-emitting portion. Also, DVC type,
In the case of the VHS type and the beta type, a light-shielding structure is provided in the vicinity of the periphery of the optical path except for the light entrance and exit.

The present invention is not limited to the above-described two-reel type magnetic tape cassette, but may be applied to a one-reel type magnetic tape cassette for data backup.

[0015]

According to the present invention, since a light shielding structure is provided around the light transmitting means, unnecessary light does not enter the light transmitting means from a portion other than the light incident portion of the light transmitting means. Therefore, erroneous detection of the leader tape due to unnecessary light entering the light transmitting means and reaching the light receiving sensor via the light emitting portion can be prevented.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of a DAT type magnetic tape cassette according to an embodiment of the present invention.

The magnetic tape cassette 2 can run with a part of the magnetic tape 10 wound around the hub 8 exposed through the front opening 12 in the upper and lower half cases 4 and 6 having translucency. Housed in. Upper and lower half cases 4, 6
Inside, a brake member 14 for preventing accidental rotation of the hub 8 when not in use, a spring 16 for urging the brake member against the hub 8, and an end or tape type of the magnetic tape 10 are detected. A prism 18 and the like for detection light used for the above are provided. A light-transmitting front cover 20 for covering the front opening 12 of the magnetic tape cassette 2 is rotatably supported on the upper half case 4 in a rotatable manner.

As described above, the housing of the magnetic tape cassette 2 is constituted by the upper and lower half cases 4, 6 and the front cover 20, and the upper and lower half cases 4, 6 and the front cover 20 have translucency. Thus, through the upper and lower half cases 4 and 6 and the front lid 20, internal components such as the hub 8 and the magnetic tape 10 can be visually checked.

The brake member 14 has a pair of brake pieces 22 at a portion facing the hub 8, and the brake pieces 22
By locking the gear portion 24 formed on the peripheral surface of the
The rotation of the hub 8 is prevented. Also, the brake member 14
Is provided with a pair of brake arms 26 extending forward, and when the front cover 20 rotates, the edge 20a of the front cover 20 locks the distal end portion 26a of the brake arm 26 and rotates. And the hub lock is released.

Under the lower half case 6, there is slidably mounted a translucent slider 28 that opens a pair of holes for the hub drive shaft and closes it when not in use. . The slider 28 is constantly urged by a spring (not shown) in a direction to close the hole of the lower half case.

FIG. 2 shows an upper half case 4 having translucency.
FIG. 3 is a perspective view of a main part showing a prism 18 provided on the inner surface of the light emitting device. The prism 18 is provided integrally with the substrate 30, and is fixed by welding the substrate 30 to the upper half case 4. When the magnetic tape cassette 2 is loaded into the recording / reproducing apparatus, the upper half case 4
The tape detection light is projected toward the tape detection hole formed in the tape. The tape detection light projected toward the tape detection hole is guided to the tape back surface through a substantially U-shaped prism, and is projected toward the tape.

Therefore, if the tape that intersects with the light emitted from the prism 18 is a transparent leader tape, the light reaches the light receiving sensor of the recording / reproducing device, and the light reaches the light receiving sensor, whereby the leader tape is detected. . The tape that intersects with the light emitted from the prism 18 is the magnetic tape 10.
In this case, since the light is blocked by the magnetic tape 10, the light does not reach the light receiving sensor, and the light does not reach the light receiving sensor, so that the magnetic tape 10 is detected.

In the vicinity of the prism 18 and the prism 18
In a region facing the light incident portion 18a and the light exit portion 18b,
The light shielding wall 32 which is a feature of the present embodiment is provided upright.
The light shielding wall 32 is provided so as to rise from the bottom of the upper half case 4, and rectangular holes 32 a and 32 b through which the detection light passes are formed near the base and near the tip. The hole 32a on the base side is the light incident side, and the hole 32b on the tip side is the light output side.
Each of the holes 32a and 32b is formed to have substantially the same shape as the light entrance 18a and the light exit 18b of the prism 18, respectively. A regulating rib 3 for regulating the upper edge of the magnetic tape 10 is provided on the front side (the back side in FIG. 2) of the prism 18.
4 is provided on the upper half case 4

The light shielding wall 32 may be provided on the upper half case 4 by integral molding, or may be molded as a separate member and then fixed to the upper half case 4. When the light shielding wall 32 is provided in the upper half case 4 by integral molding, the light shielding wall portion is molded by two-color molding using a resin material having a light shielding property or insert molding using a metal having a light shielding property. When the light shielding wall 32 is molded as a separate member, the light shielding wall 32 is molded of a resin having a light shielding property, a metal, or the like.

When the upper half case 4 is viewed from the side, the vicinity of the light entrance 18a and the light exit 18b of the prism 18 is shielded from light by the light shielding wall 32. Only the light that has passed enters the prism 18. The light emitted from the light emitting portion 18b of the prism 18 is transmitted to the light emitting side hole 3 of the light shielding wall 32.
Only the light passing through 2b reaches the light receiving sensor. Therefore, unnecessary light does not enter the prism 18 from the portion outside the light incident portion near the light incident portion 18a and is not emitted from the light emitting portion 18b, so that erroneous detection of the leader tape can be prevented beforehand. .

Next, a second embodiment of the present invention will be described. FIG. 3 is a perspective view of a main part near a prism according to the second embodiment. The second embodiment is different from the first embodiment in that the light shielding wall 36 is integrally formed on the side wall 4a of the upper half case 4. The side wall 4a of the upper half case 4
The light-shielding wall 36 extends to the vicinity of the prism 18, and light-passing holes 36 a and 36 b are formed in portions of the prism 18 facing the light incident portion 18 a and the light exit portion 18 b, respectively. The light-shielding wall 36 is formed by two-color molding using a light-shielding resin material different from the side wall 4a of the upper half case 4, or insert-molding using a light-shielding metal plate.

According to this configuration, only light passing through the light entrance side hole 36a of the light shielding wall 36 formed on the side wall 4a of the upper half case 4 enters the prism 18 as detection light in the recording / reproducing apparatus. As for the light emitted from the light emitting portion 18b, only the light passing through the light emitting side hole 36b formed in the side wall 4a of the upper half case 4 reaches the light receiving sensor.

Therefore, no extra light is incident on the prism 18 from the portion outside the light incident portion near the light incident portion 18a and is emitted from the light emitting portion 18b, thereby preventing erroneous detection of the leader tape. be able to. Further, since the side wall 4a of the upper half case 4 also functions as the light shielding wall 36, molding is easy.

Next, a third embodiment of the present invention will be described.
FIG. 4 is a perspective view of a main part near a prism according to the third embodiment. In the third embodiment, in addition to the configuration of the second embodiment, a light shielding wall 38 is provided before and after the prism 18. A horizontal portion 18 of the prism 18 is provided before and after the prism 18.
Light-shielding walls 34 and 40 higher than c are provided. These light shielding walls 34 and 40 block light traveling from the front and rear sides of the prism 18 toward the prism 18. The light shielding wall 34 on the front side (the rear side in FIG. 4) of the prism 18 is a regulating rib for regulating the tape, as in the first embodiment. The regulating rib has a light shielding function, so that the light shielding wall 34 is formed. are doing.

The light shielding wall 34 on the front side (the rear side in FIG. 4) of the prism 18 may be formed integrally with the upper half case 4 or may be formed as a separate member and then fixed to the upper half case 4. In the case of integral molding, two-color molding using a resin material having a light-shielding property different from that of the upper half case 4 or insert molding using a metal plate having a light-shielding property is performed. When molding as a separate member, it is molded using a resin or a metal plate having a light shielding property. The light blocking wall 40 on the rear side (the front side in FIG. 4) of the prism 18 is fixed to the substrate 30 of the prism 18 after being molded as a separate member.

According to such a configuration, even if the tape detecting light in the recording / reproducing apparatus is reflected or refracted by the members around the prism and may enter the prism 18 from the front and rear sides of the prism 18, such a configuration is possible. Light is the light shielding walls 34 and 40
Thus, it is possible to completely block light except for the light incident portion 18a and the light output portion 18b of the prism 18. In the third embodiment, the light shielding wall 40 on the rear side of the prism can also be used as a regulating rib for regulating the upward movement of the magnetic tape.

Next, a fourth embodiment of the present invention will be described.
FIG. 5 is a perspective view of a main part near the prism of the fourth embodiment. The fourth embodiment has a configuration in which light shielding walls 34 and 40 are provided before and after the prism 18 in addition to the configuration of the first embodiment shown in FIG. The light-shielding wall 34 on the front side (the rear side in FIG. 5) of the prism 18 also functions as a regulating rib as described above. The configuration of these light shielding walls 34 and 40 is the same as that of the third embodiment shown in FIG.

Next, a fifth embodiment of the present invention will be described.
FIG. 6 is a perspective view of a main part near the prism of the fifth embodiment. In the fifth embodiment, a light shielding wall 42 is also provided upright on the inner side of the prism 18 in the cassette left-right direction (the right side in FIG. 6). The light blocking wall 42 is formed higher than the bottom of the upper half case 4 from the tip of the prism 18, and blocks light traveling from the opening 12 in front of the cassette toward the prism 18. Therefore, even if light is directed from the opening 12 in front of the cassette to the prism 18, such light is
8 is reliably blocked by the light-shielding wall 42, so that erroneous detection of the tape due to unnecessary light from the opening 12 in front of the cassette does not occur.

Next, a sixth embodiment of the present invention will be described.
FIG. 7 is a perspective view of a main part near a prism according to a sixth embodiment. In the sixth embodiment, a light shielding portion 44 is provided below the prism 18.
Is formed. The light shielding portion 44 is formed in a portion of the upper half case 4 located below the prism 18. To form the light-shielding portion 44, the upper half case 4 and the light-shielding member are integrally molded by two-color molding or insert molding, the light-shielding member molded as a separate member is fixed to the upper half case 4, and a light-shielding paint is applied. By printing with neutral ink.

According to this configuration, the light-shielding portion 44 can be formed with almost no change in the outer shape of the upper half case 4, and the mold used conventionally can be used as it is or by slightly modifying it. The manufacture of the upper half case 4 does not become complicated.

Next, a seventh embodiment of the present invention will be described.
FIG. 8 is a perspective view of the brake member 14 according to the seventh embodiment. The brake member 14 has a light blocking wall 46 provided on the brake arm 26 in addition to the configuration shown in FIG. The light-shielding wall 46 is provided upright on the brake arm 26 so as to be located in front of the light entrance 18 a of the prism 18 when the brake member 14 is pulled out forward by the rotation of the front lid 20. The light shielding wall 46 is formed with a hole 46a at a portion facing the prism light incident portion 18a on the front end side. A space 48 corresponding to a hole is formed in a portion of the light shielding wall 46 facing the prism light emitting portion 18b on the base side. The brake member 14 originally has a light-shielding property, and the light-shielding wall 46 is formed integrally with the brake member 14.

FIG. 9 is a partial side view of the magnetic tape cassette 2 when the front cover 20 is opened. When the front cover 20 is opened and the brake member 14 is pulled out forward by the front cover 20 and the drawing is completed, the light shielding wall 46 is moved to the prism 18.
Is located in front of the light incident portion 18a. At this time, the light incident portion 18a of the prism 18 faces the hole 46a of the light shielding wall 46,
The light emitting portion faces the space 48 below the light shielding wall. And
The periphery of the light incident portion 18a is shielded from light by a light shielding wall 46. In addition, the portion 4b of the upper half case 4 around the light shielding wall 46 in a side view is subjected to a graining process, so that light shielding properties are imparted.

According to this configuration, since the periphery of the light incident portion 18a of the prism 18 is shielded from light by the light shielding wall 46, no extra light enters the light incident portion 18a. By the modification, erroneous detection of the magnetic tape 10 can be prevented.

In each of the embodiments, the light-shielding wall itself has a light-shielding property. However, even if the light-shielding wall is made of a material having a light-transmitting property, the light-shielding structure may be applied to the surface thereof. For example, light-shielding paint is applied to the surface of the light-shielding wall, printing is performed with light-shielding ink, fine irregularities are formed on the surface of the light-shielding wall (texture processing), or streaks are formed, and light is generated on the surface. The light-shielding wall may be configured to exhibit a light-shielding function by being scattered or refracted. Moreover, you may comprise combining each said embodiment suitably.

[0040]

According to the present invention, since the periphery of the light transmitting means has a light-shielding structure that does not impair the tape detecting function, even if the half case has a light-transmitting property, the recording / reproducing apparatus can be used. In such cases, the leader tape can be accurately detected, and as a result, the tape end can be accurately detected. Therefore, in a recording / reproducing device or the like,
Reliable operation is guaranteed.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a magnetic tape cassette according to an embodiment of the present invention.

FIG. 2 is a perspective view of a main part near a prism according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a main part near a prism according to a second embodiment of the present invention.

FIG. 4 is a perspective view of a main part near a prism according to a third embodiment of the present invention.

FIG. 5 is a perspective view of a main part near a prism according to a fourth embodiment of the present invention.

FIG. 6 is a perspective view of a main part near a prism according to a fifth embodiment of the present invention.

FIG. 7 is a perspective view of a main part near a prism according to a sixth embodiment of the present invention.

FIG. 8 is a perspective view of a main part of a brake member according to a seventh embodiment of the present invention.

FIG. 9 is a partial side view of a magnetic tape cassette according to a seventh embodiment of the present invention.

[Explanation of symbols]

2 Magnetic Tape Cassette 4 Upper Half Case 6 Lower Half Case 8 Hub 8a Gear Part 10 Magnetic Tape 12 Opening 14 Brake Member 16 Spring 18 Prism 20 Front Cover 22 Claw 24 Gear Part 26 Brake Arm 28 Slider 30 Substrate 32, 36, 38 , 40, 42, 46 Light shielding walls 32a, 32b, 34a, 34b, 38a, 38b, 4
6a hole 34 regulating rib 44 light shielding portion 48 gap

Claims (1)

[Claims] 1. A magnetic tape cassette in which a magnetic tape is movably accommodated in a translucent half case, wherein a periphery of a tape detecting light transmitting means provided in the half case has the tape detecting function. A magnetic tape cassette having a light-shielding structure that does not impair.