JP3041197B2 - Tape start / end detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pair of light-emitting portions disposed outside both sides of a tape cassette, and a pair of light-emitting portions disposed at the center of the tape cassette. A light guide for guiding the emitted light toward the top surface or the bottom surface of the tape cassette by total reflection,
A single light-receiving portion provided opposite to the light-emitting surface of the light guide, and the light transmitted through the high light transmittance tape provided at the start and end of the tape in the tape cassette, the start of the tape And a tape start / end detection device for detecting the end of the tape.

[0002]

2. Description of the Related Art A conventional tape start / end detection device is called V
The tape start / end detection device of the TR will be described with reference to FIGS.

A conventional tape start / end detection device is shown in FIG.
As shown in FIG. 1, a leader tape 5 having a high transmittance is provided at the beginning and end of a magnetic tape 4 wound around a pair of reels 2 and 3 in the tape cassette 1. Light transmitting windows 6, 7, 8, 9 are provided on the side and both side surfaces, respectively, and the leader tape 5 passes between the light transmitting windows 6, 7 in the central portion and the light transmitting windows 8, 9 on both side surfaces. It is configured as follows.

[0004] A pair of light emitting elements 11 and 12 are provided so as to be located at the center of the tape cassette 1, and a pair of light emitting elements 11 and 12 are located at both side ends of the tape cassette 1 and face the light emitting elements 11 and 12. Light receiving element 13,
The light emitting elements 11 and 12 are provided so that the light emitted from the light emitting elements 11 and 12 is received by the light receiving elements 13 and 14 through the light transmitting windows 6, 7, 8 and 9 of the tape cassette 1.

[0005] In the tape start / end detecting device constructed as described above, the light receiving elements 11 and 12 detect the presence or absence of the transmission of light from the light emitting elements 11 and 12, so that the leader is provided at either end. The start and end of the magnetic tape 4 are detected by determining whether the tape 5 is present.

As another prior art, as shown in FIG. 7, a pair of light receiving elements 23 and 24 are provided so as to be located at both side ends of a tape cassette 1 similar to the above-mentioned conventional example. So that it is located in the center of 1,
A light guide 25 for guiding light toward both sides where the light receiving elements 23 and 24 are provided by total reflection is provided.
A single light emitting element 21 is provided to face the light incident surface of the tape, and the presence or absence of transmission of light from the single light emitting element 21 is detected by the pair of light receiving elements 23 and 24. A tape start / end detection device for detecting the end has been proposed.

Further, as another conventional example, as shown in FIG. 8, a tape cassette 1 similar to the above-mentioned conventional example is used.
A pair of light emitting elements 31 and 32
The light emitted from the light emitting elements 31 and 32 and guided by the light guides 36 and 37 is directed toward the bottom surface of the tape cassette 1 by total reflection so as to be located at the center of the tape cassette 1. A light guide 35 for guiding is provided,
A single light receiving element 33 is provided to face the light emitting surface of the light guide 35, and the light receiving elements 33,
A tape start / end detection device that detects the start and end of the tape by detecting the presence or absence of the transmission of light from the tape 2 has been proposed (see JP-A-5-182293).

[0008]

In the conventional tape start / end detecting device shown in FIG. 6, a pair of light emitting elements 1 are provided.
1 and 12 and light receiving elements 13 and 14 are required, respectively, and there is a problem that the price is high and the current consumption is high.
Note that even if a double-sided light emitting element is used as the light emitting element,
After all it is high price.

The conventional tape start / end detecting device shown in FIG. 7 is inexpensive because it comprises a single light emitting element 21, a pair of light receiving elements 23 and 24, and a light guide 25. However, since the light flux from the single light emitting element 21 is divided into two by the light guide 25, high-luminance light emission is required,
This light-emitting element 21 requires high current consumption in light emission, and thus has a problem that the light-emitting element 21 changes with time quickly and its life is shortened.

Further, in the conventional tape start / end detection devices shown in FIGS.
Since the tapes 3, 14, 23, and 24 are located outside the tape cassette 1, there is a problem that a malfunction due to extraneous light is likely to occur, and it is necessary to take some sort of light shielding measure.

Further, the conventional tape starting end shown in FIG.
The end detection device is inexpensive because it is provided with a pair of light emitting elements 31, single light receiving elements 33 and 34, and a light guide 35. However, as shown in FIG.
Of the light fluxes 4 from the light emitting elements 31 and 32
3 and 44, and the total reflection surfaces 40 and 41 are at 45 ° to the light fluxes 43 and 44. Therefore, the respective light fluxes 43 and 44 reach the right and left of the light receiving element 33 separately. Not only is it very inefficient, but also
In the case where the light beams 3 and 44 have slight variations in height, direction, and the like, the light beams 43 and 44 respectively reach the left and right invalid portions of the light receiving element 33, and sufficient light does not reach the light receiving element. There was a problem of causing a malfunction.

The present invention has been made in view of the above points, and provides an inexpensive tape start / end detection device capable of reliably guiding a light beam from a light emitting section to a light receiving section. The purpose is to:

[0013]

In order to solve the above-mentioned problems, a tape start / end detecting device according to the first invention of the present application comprises a pair of tape detectors respectively disposed outside both sides of a tape cassette. A light emitting unit, a light guide disposed at a central portion of the tape cassette, and guiding the light emitted from the light emitting unit toward the top surface or the bottom surface of the tape cassette by total reflection; A single light-receiving portion provided opposite to the light exit surface of the body, and the light transmitted through the high light transmittance tape provided at the beginning and end of the tape in the tape cassette, the start and end of the tape. In the tape start / end detection device for detecting, a pair of incident surfaces facing the light emitting portion of the light guide are inclined at a predetermined angle so that light from the light emitting portion is totally reflected and then condensed on the light receiving portion. Let me do A.

[0014]

The tape start-end detecting device according to the second aspect of the present invention, a pair of light emitting portions which are arranged such that respective positions <br/> location on either side outside of the tape cassette, the central portion of the tape cassette And a columnar light guide for guiding the light emitted from the light emitting portion toward the top surface or the bottom surface of the tape cassette by total reflection, and confronting the emission surface of the light guide. Start and end detection for detecting the start and end of the tape by light transmitted through the high light transmittance tape provided at the start and end of the tape in the tape cassette. In the device,
The light guide has a pair of incident surfaces facing the light emitting portion formed on a diffusion surface for diffusing light from the light emitting portion.

[0016]

In the tape start / end detecting device according to the first invention of the present application, a pair of incident surfaces facing the light emitting portion of the light guide are focused on the light receiving portion after the light from the light emitting portion is totally reflected. As described above, since the light beam is inclined at a predetermined angle, the direction of travel of the light beam from the light emitting unit due to refraction can be corrected and guided to the light receiving unit without fail.

[0017]

In the tape start / end detecting device according to the second invention of the present application, a pair of incident surfaces facing the light-emitting portion of the light guide are used as diffusion surfaces for diffusing light from the light-emitting portion, and the area of the incident light beam is determined. the since the expansion, it is possible to guide the light beam from the light-emitting part to ensure that the light-receiving part.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a tape start / end detecting device according to the present invention will be described below with reference to FIGS. 1 and 2. Is omitted. Here, FIG. 1 is a schematic top view showing the tape start / end detecting device of the present embodiment, and FIG. 2 is an enlarged side view showing the main part of the tape start / end detecting device of the present embodiment.

In FIG. 1, a box 1 indicated by a two-dot dashed line is a tape cassette, 2 and 3 are a tape supply and take-up reel, 4 is a magnetic tape, and 5 is a high light provided at the beginning and end of the magnetic tape 4. Leader tape for transmittance, 31,3
Reference numeral 2 denotes a light emitting element that emits light beams 43 and 44 to the center of the tape cassette 1 via light guides 36 and 37, and 55 denotes a light beam 4
3 and 44, the light receiving element 33 is totally reflected by the prism.
Are light guides for guiding the light beams 43 and 44. The light guide 55 is made of acrylic and has a refractive index of 1.49.

The light guide 55 according to this embodiment is
As shown in FIG. 2, a pair of incident surfaces 58 and 59 facing the light emitting elements 31 and 32 are inclined by a predetermined angle θ °, and the light beams 43 and 44 from the light emitting elements 31 and 32 are (45)
+ Θ) °.

For this reason, the luminous fluxes 43 and 44 from the light emitting elements 31 and 32 are refracted on the incident surfaces 58 and 59, enter the total reflection surfaces 60 and 61 at an angle of 45 ° or less, and are totally reflected. Becomes Then, the totally reflected light fluxes 43 and 44 are
The light is condensed almost at the center of the light exit surface 62, emitted from there, and surely reaches the light receiving element 33.

In the above embodiment, the incident surfaces 58, 5
9 is calculated based on the total optical path length, the distance from the emission surface 62 to the light receiving element 33, and the like. In the present embodiment, the inclination angle θ is set to 4.25 °. In this manner, the light fluxes 43, 44 according to the angles of the incident surfaces 58, 59.
Can be adjusted (the degree of light condensing on the light receiving element 33), so that fine adjustment can be easily performed.

Next, a description will be given of a second embodiment of a tape start / end detecting device according to the present invention, by referring to FIG. 3. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Is omitted. Here, FIG. 3 is an enlarged side elevational view showing the main part of the tape start / end detection device of the present embodiment.

As shown in FIG. 3, in the light guide 65 according to this embodiment, the incident surfaces 68 and 69 are perpendicular to the light beams 43 and 44 from the light emitting elements 31 and 32 as in the above-described conventional example. However, a pair of total reflection surfaces 70 and 71 facing the light emitting elements 31 and 32 are inclined at a predetermined angle ψ ° from 45 °, and the light fluxes 43 and 44 from the light emitting elements 31 and 32 are (4)
5-ψ) °.

For this reason, the luminous fluxes 43 and 44 from the light emitting elements 31 and 32 enter the incident surfaces 68 and 69 without being refracted, and enter the total reflection surfaces 60 and 61 at an angle of (45-ψ) ° or less. And is totally reflected. The totally reflected light fluxes 43 and 44 are condensed substantially at the center of the emission surface 62, emitted from there, and surely reach the light receiving element 33.

In the above embodiment, since the refractive index of the light guide 65 is 1.49, sin ^-1 (1 / 1.49)
= 42.16 °, the light flux 4 at an angle of 42.16 ° or more
It can be seen that when the light beams 3, 44 are incident, the light beams 43, 44 are totally reflected. Therefore, the tilt angle ψ ° can be set between 0 ° and 2.84 °, but is determined in consideration of the length of the light guide 65, the size of the light receiving surface of the light receiving element 33, and the like. However, since the angles of the light beams 43 and 44 after total reflection change at twice the angle of inclination of the total reflection surfaces 70 and 71, it is necessary to tighten the tolerance.

A third embodiment of the tape start / end detecting device according to the present invention will be described with reference to FIG. 4. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Omitted. Here, FIG. 4 is an enlarged side elevational view showing the main part of the tape start / end detection device of this embodiment.

As shown in FIG. 4, in the light guide 75 according to the present embodiment, a pair of incident surfaces 78 and 79 facing the light emitting elements 31 and 32 are inclined by a predetermined angle θ °, and the incident surfaces 78 are inclined. , 79 are intentionally roughened so that the light beams 43 and 44 from the light emitting elements 31 and 32 are diffused.

Therefore, the luminous fluxes 43 and 44 from the light emitting elements 31 and 32 are diffused on the incident surfaces 78 and 79 of the light guide 75 and are totally reflected on the total reflection surfaces 80 and 81 in a state where the cross-sectional area becomes large. Will be done. And the light flux 4 totally reflected
The light beams 3 and 44 are emitted from almost the entire emission surface 82 and reach the light receiving element 33 without fail.

In the above embodiment, the entrance surfaces 78 and 79 of the light guide 75 are roughened by using a mold that does not polish the surface corresponding to the entrance surfaces 78 and 79 until the final step. This can be realized by manufacturing the light guide 75,
If necessary, the mold surface may be subjected to blasting, etching, or the like. Further, it is also possible to adjust the light amount by adjusting the surface roughness of the incident surfaces 78 and 79 of the light guide 75. For example, when the light transmittance of the magnetic tape is changed, Also the incident surface 7
By adjusting the surface roughness of 8, 79, it is possible to adjust to an appropriate light amount.

Next, a description will be given of a fourth embodiment of the tape start / end detecting device according to the present invention, by referring to FIG. 5. The same parts as those in the first embodiment are designated by the same reference numerals. Omitted. Here, FIG. 5 shows the tape starting end of this embodiment.
It is a principal part enlarged side view explanatory drawing which shows an end detection apparatus.

As shown in FIG. 5, the light guide 85 according to this embodiment has a pair of incident surfaces 88 and 89 facing the light emitting elements 31 and 32 inclined by a predetermined angle θ °, and the incident surfaces 88 and 89 are inclined. , 89 are intentionally roughened.
The emission surface 92 is configured to have a convex lens shape.

For this reason, the entrance surfaces 78 and 79 of the light guide 75
In the state where the cross-sectional area is increased by being diffused by the
The light fluxes 43 and 44 totally reflected at 0 and 81
The light is emitted again to be condensed, and the light receiving element 3
Reach 3

In the first to fourth embodiments, only the light guides 55, 65, 75, 85 on the light receiving element 33 side have been described. For the 37 as well, by performing measures such as making the total reflection surface rough or making the surface facing the light receiving element 33 a convex lens shape, it is possible to more reliably detect the tape start / end.

The first to fourth embodiments may be appropriately combined to adjust the angles of the light beams 43 and 44 so that the light beams 43 and 44 can reach the light receiving element 33 without fail. Needless to say, it's good.

[0037]

Since the tape start / end detecting device according to the present invention is provided with a pair of light emitting portions, a single light receiving portion and a light guide, it is not only inexpensive, but also a single type. Is provided so as to be located inside the center of the tape cassette, so that it is not necessary to take measures against malfunction due to disturbance light. Further, the light emitted from the pair of light-emitting portions can be reliably transmitted to the light-receiving portion by the light guide, so that the transmission efficiency can be improved and the malfunction can be suppressed as much as possible.

[Brief description of the drawings]

FIG. 1 is a schematic top view showing a first embodiment of a tape start / end detecting device according to the present invention.

FIG. 2 is an enlarged schematic side view showing a main part of the first embodiment of the tape start / end detecting device of the present invention.

FIG. 3 is an enlarged schematic side view of a main part of a second embodiment of the tape start / end detection device of the present invention.

FIG. 4 is an enlarged schematic side view of a main part of a tape start / end detecting device according to a third embodiment of the present invention.

FIG. 5 is an enlarged schematic side view showing a main part of a tape start / end detecting device according to a fourth embodiment of the present invention.

FIG. 6 is a schematic top view showing a conventional tape start / end detection device.

FIG. 7 is a schematic side view showing another conventional tape start / end detection device.

FIG. 8 is a schematic side view showing another conventional tape start / end detection device.

FIG. 9 is an enlarged schematic side view of a main part in FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tape cassette 2, 3 reel 4 Magnetic tape 5 Leader tape 31, 32 Light emitting element 33 Light receiving element 36, 37 Light guide 43, 44 Light flux 55 Light guide 58, 59 Incident surface 60, 61 Total reflection surface 62 Emission surface 65 Light guides 68, 69 Incident surfaces 70, 71 Total reflection surfaces 72 Emission surfaces 75 Light guides 78, 79 Incident surfaces 80, 81 Total reflection surfaces 82 Emission surfaces 85 Light guides 88, 89 Incident surfaces 90, 91 Total reflection surfaces 92 Outgoing surface

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-182293 (JP, A) JP-A-53-69009 (JP, A) JP-A-4-31428 (JP, U) JP-A-62-1 26637 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G11B 15/08

Claims (2)

(57) [Claims] 1. A pair of light-emitting portions disposed so as to be located outside both sides of a tape cassette, and light emitted from the light-emitting portion, which is disposed so as to be located at a central portion of the tape cassette. A light guide that guides the tape cassette toward the top surface or the bottom surface by total reflection, and a single light receiving unit provided to face the emission surface of the light guide. In a tape start / end detection device that detects the start and end of the tape by light transmitted through the high light transmittance tape provided at the end, a pair of light-entering surfaces facing the light-emitting portion of the light guide are formed by a light-emitting portion. The tape start / end detecting device is inclined at a predetermined angle so that light from the tape is totally reflected and then condensed on the light receiving portion. 2. A pair of light-emitting portions disposed so as to be located outside both sides of the tape cassette, and light emitted from the light-emitting portion disposed so as to be located at the center of the tape cassette. It has a columnar light guide that guides the tape cassette toward the top surface or bottom surface by total reflection, and a single light receiving unit that is provided to face the emission surface of the light guide. In a tape start / end detection device that detects the start and end of the tape by light passing through the high light transmittance tape provided at the start and end,
A tape start / end detection device, wherein a pair of incident surfaces of the light guide opposing the light emitting portion are diffusion surfaces for diffusing light from the light emitting portion.