JPH0531735Y2 - - Google Patents

Description

[Detailed Description of the Invention] The magnetic tape cassette of the present invention will be explained according to the following items.

A. Field of industrial application B. Overview of the invention C. Prior art D. Problem that the invention attempts to solve E. Means for solving the problem F. Example [Figures 1 to 7] a. Cassette case [Figure 1] Figures 5 to 7
Figure] b Transparent substrate [Figure 1, Figure 3, Figure 4, Figure 6
Figures, Figures 7] c Cover [Figures 2 and 3] d Tape reel [Figures 3 and 7] e Magnetic tape [Figures 3 and 7] f Operation [Figure 7] g Transparent Modifications of the board [Figs. 8 to 11] g-1 Modification 1 [Figs. 8 and 9] g-2 Modification 2 [Figs. 10 and 11] G Effects of the invention (A Industry The present invention relates to a novel magnetic tape cassette.
Specifically, in a magnetic tape cassette that can detect the tape end using an optical sensor, we have developed a new magnetic tape cassette that can prevent malfunctions caused by ambient light, has a simpler structure, and is easier to manufacture. The aim is to provide tape cassettes.

(B Overview of the invention) The magnetic tape cassette of the invention has a number of layers or holes formed on the side surface of the cassette case to receive light from a light source located inside the cassette case, or at a position close to the light transmission hole. Equipped with a plate-shaped transparent substrate on which cylindrical light guides are arranged,
Light traveling straight from the direction of the light source toward the light transmission hole is transmitted, and light having an incident angle different from that of the light is attenuated within the transparent substrate and almost blocked. Therefore, the transparent substrate prevents light that has entered the cassette case through the window from passing through the light transmission hole, thereby preventing false detection of the tape end. The present invention is designed to be simple, easy to manufacture, and not hinder miniaturization of the cassette case.

(C Prior Art) A recording/reproducing device using a magnetic tape cassette,
For example, tape cassette type audio tape recorders, tape cassette type video tape recorders,
For tape cassette type digital audio tape recorders, etc., prevent damage to the tape,
In order to prevent an excessive load from being placed on the tape drive system, it is possible to detect when the magnetic tape has been unwound from the tape reel to the end, that is, the end of the tape, and either stop the device or stop the magnetic tape. It is necessary to make the vehicle run in the opposite direction.

To this end, we use a transparent tape, the so-called leader tape, that connects the end of the magnetic tape and the tape reel, and we form a light-transmitting hole on the side of the cassette case, allowing the magnetic tape cassette to be attached to a recording/playback device. Then, the light source and optical sensor installed in the recording/reproducing device are arranged to face the magnetic tape with the light transmission hole in between, and at the end of the tape, the light from the light source passes through the transparent leader tape and the light transmission hole. It has been proposed that the light is received by an optical sensor, and the end of the tape can be detected based on this light.

However, if light from outside the cassette case enters the cassette case through the window formed in the cassette case and enters the sensor through the light transmission hole, the tape will be recorded even though it has not reached the end. There is a risk that the playback device may malfunction by performing the operation at the end of the tape.

Therefore, for example, Japanese Utility Model Application Publication No. 60-102787 proposes interposing a lock plate between the light source and the light transmission hole and providing a tunnel portion in the lock plate.

(D. Problems to be Solved by the Invention) However, in order to reduce the transmittance of light traveling along an optical path that is angled with respect to the optical path of light traveling straight from the direction of the detection light source, a fairly long tunnel section is required,
This poses a problem in that it hinders the miniaturization of the cassette case.

Furthermore, if the tunnel section were to be formed on the side wall of the cassette case, the direction of die cutting during molding would be complicated, requiring a mold with a complex configuration such as a slide mold, which would increase manufacturing costs. There is also the problem that it increases the price.

(E. Means for Solving Problems) In order to solve the above-mentioned problems, the magnetic tape cassette of the present invention has a light transmission hole formed on the side surface of the cassette case to receive light from a light source located inside the cassette case. A plate-shaped transparent substrate on which a large number of layered or cylindrical light guides are arranged is installed inside or in a position close to the light transmission hole, and the light guides extend straight from the direction of the light source toward the light transmission hole. In addition to transmitting light, light having an incident angle different from the incident angle of the light is attenuated within the transparent substrate and is almost blocked.

Therefore, in the magnetic tape cassette of the present invention, the disturbance light that enters the cassette case through the window is blocked by the transparent substrate, so that it passes through the light transmission hole and is received by the optical sensor. There is no
Misdetection of the tape end can be prevented.

In addition, since it is only necessary to place the transparent substrate within the light transmission hole or close to the light transmission hole, there is no problem with miniaturizing the cassette case, and furthermore, it is not necessary to cut out the mold as in the case of providing a tunnel section. The direction does not become complicated, and an increase in manufacturing cost can be avoided.

(Embodiment F) [Figs. 1 to 7] The details of the magnetic tape cassette of the present invention will be explained below according to the illustrated embodiment 1.

(a) Cassette case [Figs. 1 to 5, 7] Reference numeral 2 in the figure indicates a cassette case, which is composed of a lower half 3 and an upper half 4.

Reference numeral 5 designates the bottom plate of the lower half 3, which has a substantially horizontally long rectangular shape, and has a tape drawer recess 6 cut out into a substantially horizontally long rectangular shape at its front edge, leaving both ends intact. Furthermore, approximately one-third of the left and right edges of the bottom plate 5 from the front end are cut into narrow widths.

A peripheral wall 7 is erected upward from the peripheral edge of the bottom plate 5, excluding the left and right ends of the front edge, and the two places where the peripheral wall 7 is not formed are tape entrances and exits. ,8'.

Furthermore, since the peripheral wall 7 is formed along the periphery of the bottom plate 5, the front one-third portions 7a', 7b' of the left and right side walls 7a, 7b are slightly recessed inward.

9, 9, . . . are boss portions erected from predetermined locations on the bottom plate 5, and each boss portion 9, 9, . There is.

Reference numeral 10 denotes a light source insertion hole formed in contact with the inside of the substantially central portion of the front surface portion 7c along the tape pull-out recess 6 in the peripheral wall 7, and a cylindrical portion 11 stands up from the periphery of the insertion hole 10. has been done. Cutouts 11a, 11a are formed on both the left and right sides of the cylindrical portion.

Of the upper edges of portions 7a' and 7b' of the left and right side walls 7a and 7b that are slightly recessed inward, the portions through which the notches 11a and 11a provided in the cylindrical portion 11 can be seen are provided with light. Notch 1 that becomes a through hole
2 and 12 are formed. And lower half 3
When the upper half 4 and the upper half 4 are combined to form the cassette case 2, these notches 12, 12 become light transmission holes.

Reference numerals 13 and 13 are large insertion holes formed at positions spaced to the left or right from the center of the bottom plate 5, respectively.

14 is the top plate of the upper half 4. The top plate 14 has a shape substantially corresponding to the bottom plate 5 of the lower half 3, and peripheral walls 15 projecting downward are formed on the rear edge, left and right side edges, and front edge, respectively. The planar shape of these peripheral walls 15 is formed to have approximately the same shape as the corresponding portions of the peripheral wall 7 of the lower half 3, so that when the two halves 3 and 4 are joined, the respective peripheral walls 7 and 15 are butted. It is becoming more and more popular.

A large window portion 16 extending in the left-right direction is formed on the top plate. The window portion 16 is made of transparent synthetic resin. Note that this window portion 16 and other portions of the upper half 4 are integrally formed by a so-called multicolor molding method.

17, 17, . . . are boss portions integrally formed on the top plate 14, and are formed at locations corresponding to the boss portions 9, 9, .
Further, these boss portions 17, 17 are formed with lower holes 17a, 17a, . . . that are open at the lower ends.

Thus, the lower half 3 and the upper half 4 are overlapped so that the tips of the peripheral walls 7 and 15 are butted against each other, and the connecting screws 18, 18, . 9, 9, . . . are inserted through the insertion holes 9a, 9a, . . . and formed in the boss portions 17, 17, . . . of the upper half 4.
a, 17a, . . . to form a cassette case 2.

(b Transparent Substrate) [Figures 1, 3, 4, 6, 7] Reference numerals 19 and 19 indicate transparent substrates that are fitted into the light transmission holes 12 and 12, and Most of the light that travels straight from the cutouts 11a, 11a of the cylindrical portion 11 toward the light transmission holes 12, 12 is transmitted, but the light that travels along the optical path that is at an angle to the optical path of the light is transmitted. It is configured so that almost no light is transmitted through it.

Such a transparent substrate may have any configuration, but for example, as shown in the figure, a large number of light shielding stripes 21, 21, . . . are arranged in a grid pattern in a plate-shaped transparent substrate 20, The strips 21, 21, . . . have a constant width in the thickness direction of the transparent substrate 20, and the width direction is generally along the line connecting the cutouts 11a, 11a and the light transmission holes 12, 12. Something like that is fine.

Therefore, the notches 11a, 11a and the light transmission hole 12,
The light that has traveled on an optical path having an angle with respect to the line connecting 12 and entered the transparent substrates 19, 19 is
Most of the light incident on the light-shielding stripes 21, 21, .

(c Cover) [FIGS. 2 and 3] Reference numeral 22 denotes a cover rotatably provided on the front surface of the cassette case 2. That is, the cover 22
is supported by the cassette case 2 so as to be rotated between a closed position in which the front surface of the tape drawer recess 6 of the cassette case 2 is closed and an open position in which the front surface of the tape drawer recess 6 is open; The resilient force of a resilient means (not shown) is applied so that the cover 22 is always in the closed position. When the magnetic tape cassette 1 is installed in the recording and reproducing apparatus, the cover 22 is rotated to the open position against the elastic force by a cover opening member provided on the recording and reproducing apparatus. It's summery.

(d Tape reel) [Figures 3 and 7] Reference numerals 23a and 23b are tape reels, each consisting of a hub 24 and flanges 25 and 26 integrally formed at both upper and lower ends of the hub 24. Become. The upper flange 16 is made of a transparent material so that the amount of magnetic tape wound can be confirmed through the window 16 of the cassette case 2 and the upper flange 26. .

The hub 24 also has an engagement hole 27 opened at the lower end.
is formed.

And such tape reels 23a, 23
b is rotatably arranged inside the cassette case 2. The engagement holes 27, 27 formed in the respective hubs 24, 24 are exposed to the outside through the insertion holes 13, 13 formed in the bottom plate 5 of the cassette case 2.

(e Magnetic tape) [Figures 3 and 7] 28 is a magnetic tape, both ends of which are connected to the reel hubs 24, 24 of the tape reels 23a, 23b via transparent leader tapes 29a, 29b, and , wrapped. Then, the magnetic tape 25 is placed on the left tape reel 23a (hereinafter referred to as
It's called "S reel". ) to the left tape entrance/exit 8
It exits the cassette case 2 through the tape drawer recess 6, crosses the front surface of the tape drawer recess 6, enters the cassette case 2 again through the right tape entrance 8', and enters the right tape reel 23b (hereinafter referred to as the "T reel"). A path is passed through which it is wound up. Therefore, the cutouts 11a, 11a of the cylindrical portion 11 and the light transmission hole 1 described above
A magnetic tape 28 crosses between 2 and 12.

The magnetic tape 28 has a cassette case 2.
When the tape is attached to a recording/reproducing device for recording and/or playback, it is further pulled out from the cassette case 2 and run through a predetermined tape path, such as being wound around a rotating magnetic head. It's becoming like that. During recording and playback and high-speed winding, it is unwound from the S reel 23a and wound onto the T reel 23b, and during reverse playback and rewinding, it is unwound from the T reel 23b and wound onto the S reel 23a. ing.

(f Operation) [Figure 7] When the magnetic tape cassette 1 is installed in the recording/reproducing apparatus, the light source 30 provided in the recording/reproducing apparatus is inserted into the cassette case through the light source insertion hole 10 provided in the bottom plate 5. 2 is inserted into the cylindrical part 1
It is located within 1. Further, light receiving sensors 31a and 31b, which are also provided in the recording and reproducing apparatus, are brought close to the light transmission holes 12 and 12 from outside the cassette case 2,
It faces the light source 30 through the light transmission holes 12, 12 and the notches 11a, 11a provided in the cylindrical portion 11.

When the magnetic tape 28 is completely wound onto the T-reel 23b, the light source 30 and the light receiving sensor 31
Since the magnetic tape 28 that was blocking the optical path between the light source 30 and the light source 30 is removed and the transparent leader tape 29a is positioned between the optical paths, the light from the light source 30 is received by the light receiving sensor 31a, and the light from the light source 30 is received by the light receiving sensor 31a. As a result, it is detected that the entire magnetic tape 28 has been wound onto the T-reel 23b, that is, the end of the tape during forward running is detected.

Conversely, when the magnetic tape 28 is completely wound onto the S reel 23a, a transparent leader tape 2 is placed in the optical path between the light source 30 and the right light receiving sensor 31b.
9b is lying horizontally, the light from the light source 30 is received by the light receiving sensor 31b, and thereby the magnetic tape 28 is completely wound onto the S reel 23a, that is, the end of the tape during reverse running is detected. Detected.

A large window 16 is formed in the top plate 14 of the cassette case 2, and even if some external light enters the cassette case 2 through the window 16, such light will be filtered through the transparent substrate 19, 19, such external light is not directly received by the light receiving sensor 31a or 31b. Therefore, the recording/reproducing device may determine that the tape is at the end even though it is not the end of the tape. It is possible to effectively prevent a malfunction in which a predetermined operation is performed.

(g Modifications of Transparent Substrate) [FIGS. 8 to 11] Next, some modifications of the transparent substrate will be described.

(g-1 Modification 1) [FIGS. 8 and 9] FIGS. 8 and 9 show Modification 1 of the transparent substrate.

32 is a modification of the transparent substrate.

The transparent substrate 32 is formed by integrally forming a honeycomb-shaped light-shielding strip 34 in a transparent substrate 33 having a plate shape. The width direction of the light shielding strip 34 is along the thickness direction of the transparent substrate 33, and the width direction of the light shielding strip 34 is approximately the same as the direction in which the line connecting the notch 11a of the cylindrical portion 11 and the light transmission hole 12 extends. The peripheral wall 7 of the lower half 3 is aligned so as to close the light transmission hole 12.
attached to the inner surface of the

(g-2 Modification 2) [Figures 10 and 11] Figures 10 and 11 show Modification 2 of the transparent substrate.

Reference numeral 35 denotes a transparent substrate, and a large number of optical fibers 36, 36, . The transparent substrate 35 is installed inside the cassette case so that the optical axis direction of each optical fiber 36, 36, . made to follow the line.

(G. Effect of the invention) As is clear from the above description, in the magnetic tape cassette of the invention, a tape reel wound with magnetic tape is rotatably arranged inside the cassette case, and the tape reel is placed on the top surface of the cassette case. In a magnetic tape cassette in which a window portion through which at least a portion of the tape can be seen is formed, the window portion is formed in a side surface of the cassette case and receives light from a light source located inside the cassette case. is equipped with a plate-shaped transparent substrate formed by arranging a large number of layered or cylindrical light guides, which transmits light traveling straight from the direction of the light source toward the light transmission hole, and also controls the incidence of the light. The present invention is characterized in that light having an incident angle different from the angle is attenuated within the transparent substrate and is almost blocked.

Therefore, in the magnetic tape cassette of the present invention, the disturbance light that enters into the cassette case through the window is blocked by the transparent substrate, and therefore does not pass through the light transmission hole and be received by the optical sensor. , it is possible to prevent false detection of the tape end.

In addition, since it is only necessary to place the transparent substrate within the light transmission hole or close to the light transmission hole, there is no problem with miniaturizing the cassette case, and furthermore, it is not necessary to cut out the mold as in the case of providing a tunnel section. The direction does not become complicated, and an increase in manufacturing cost can be avoided.

[Brief explanation of drawings]

Figures 1 to 7 show an example of the implementation of the magnetic tape cassette of the present invention. Figure 1 is a perspective view of the main parts, Figure 2 is a perspective view of the whole, and Figure 3 is a perspective view of the magnetic tape cassette with the upper half removed. A perspective view of the state, Figure 4 is a plan view of the lower half, Figure 5 is a bottom view of the upper half, Figure 6 conceptually shows the transparent substrate, Figure A is a front view, Figure B is Figure A. FIG. 7 is a schematic plan view for explaining the operation, and FIGS. 8 and 9 conceptually show a modified example of the transparent substrate in the magnetic tape cassette of the present invention. 8 is a front view, FIG. 9 is an enlarged cross-sectional view taken along the line - in FIG. 8, and FIGS. 10 and 11 conceptually illustrate Modified Example 2 of the transparent substrate. , FIG. 10 is a front view, and FIG. 11 is a partially cutaway perspective view. Explanation of symbols, 1...Magnetic tape cassette, 2...
...Cassette case, 12...Light transmission hole, 16...
Window portion, 19... Transparent substrate, 21... Light guide, 23
a...Tape reel, 23b...Tape reel,
28... Magnetic tape, 30... Light source, 32... Transparent substrate, 34... Light guide, 35... Transparent substrate, 3
6...Light guide.

Claims (1)

[Scope of Claim for Utility Model Registration] A magnetic tape cassette in which a tape reel wound with magnetic tape is rotatably arranged in a cassette case, and a window is formed on the top surface of the cassette case through which at least a portion of the tape reel can be seen. A large number of layered or cylindrical light guides are arranged in or near the light transmission hole formed on the side surface of the cassette case to receive light from a light source located inside the cassette case. A plate-shaped transparent substrate is provided to transmit light traveling straight from the direction of the light source toward the light transmission hole, and to transmit light having an incident angle different from the incident angle of the light within the transparent substrate. A magnetic tape cassette characterized by being attenuated so as to be almost completely cut off.