JP2003296989A - Tape end detection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a tape end by using a light from an LED with a high degree of accuracy without being affected by a reflected light from a reel flange in a cassette by a tape end detection apparatus used for a magnetic recording and reproducing apparatus such as a VTR. <P>SOLUTION: A light emitted from a supply side light emitting section (LED) 5 placed at a side of a supply side optical path forming hole 9 of a cassette 1 toward the inside of the cassette 1 is led to an incident face of a prism 7 placed in a tape detection hole 13, reflected in a reflection face 14, and received by a light receiving element 8 beneath the prism 7. A tape 2 supplied from a supply reel 3 is in crossing with the midway of a supply side optical path 15. The supply side optical path 15 is tilted to a cassette reference face (bottom face) by a prescribed angle θ to reduce a luminescent luminous quantity downward thereby reducing a reflected light led to the incident face of the prism 7 from the lower side reel flange 11 and decreasing the possibility of malfunction. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape end detecting device used in a magnetic recording / reproducing device such as a VTR, and more specifically, it is stable without being affected by reflected light from a reel flange of a cassette. The present invention relates to a tape end detecting device capable of detecting a tape end with high accuracy.

[0002]

2. Description of the Related Art As a conventional example of a tape end detecting device for a cassette tape loaded in a magnetic recording / reproducing device such as a VTR, those shown in FIGS. 3 and 4 are known. FIG. 3 is a schematic plan sectional view showing a state in which a cassette is loaded in the conventional tape end detecting device, and FIG. 4 is a sectional view taken along the line BB of FIG. 3 and 4, the cassette 1 is provided with a supply reel 3 around which a tape 2 is wound and a take-up reel 4, and the tape 2 supplied from the supply reel 3 is a tape running system (not shown) in the mechanism section. No.) and is taken up by the take-up reel 4. LE is provided on each side of the supply-side optical path forming hole 9 and the winding-side optical path forming hole 10 of the cassette loaded in the cassette loading position of the mechanism section.
A supply side light emitting section 5 and a winding side light emitting section 6 made of D are arranged. The supply side optical path 15 and the winding side optical path 16 of the light emitted from the light emitting parts 5 and 6 toward the inside of the cassette 1 are tape detection holes provided in the middle of both reels 3 and 4 of the cassette 1. The light is guided to the prism 7 disposed inside the light guide 13, and is received by the light receiving element 8 installed on the cassette loading surface immediately below the prism 7. One supply side optical path 15
The tape 2 supplied from the supply reel 3 intersects in the middle of, and the tape 2 wound on the winding reel 4 intersects in the middle of the other winding-side optical path 16.

The tape 2 has a tape portion having a high light transmittance at both ends of a recording portion having a low light transmittance, and the difference in the amount of light incident on the light receiving portion 8 can be optically read from the difference in the light transmittance. The tape end can be detected by. Further, the supply side light emitting section 5 and the winding side light emitting section 6 emit light intermittently with a time difference, and by detecting the light reception in synchronization with each light emission, the start end and the end of the tape are detected.
In such a magnetic recording / reproducing apparatus, as a conventional example for preventing a malfunction of the tape end detecting apparatus, an actual flat disk 4-
The invention described in Japanese Patent No. 62527 is known, and in this conventional example, in order to prevent light reflected from the inner wall surface of the magnetic tape cassette and traveling toward the light receiving element from reaching the light receiving element, the outside of the tape cassette is known. Reflected light blocking means is provided on the front surface of the light receiving element arranged at.

[0004]

However, the effect of blocking reflected light of the invention disclosed in Japanese Utility Model Laid-Open No. 62527/1992 is obtained by increasing the length of the reflected light blocking means. There was a problem in that it was necessary to secure more space in order to increase by the way,
In the conventional example shown in FIG. 3 described above, the planar optical paths 15 and 16 from the light emitting portions 5 and 6 to the tape detecting hole 13 and the optical path forming hole 9 provided in the cassette 1 shown in FIG. 1
0 and the height (H) are defined by the cassette format, and the optical paths 15 and 16 are generally configured to be parallel to the reference plane (bottom surface) of the cassette 1 at this height (H). However, in such a configuration, for example, when the specified height is offset from the tape center, the reflected light from the reel flange portion on the cross section of the planar optical paths 15 and 16 passes through the prism 7. The light receiving unit 8 may receive the light.

FIG. 5 is a schematic plan sectional view for explaining the problems of the tape end detecting device shown in FIG. 3, and FIG. 6 is a C cross section of FIG.
It is a -C line sectional view. The tape end detecting device shown in FIGS. 3 and 4 shows the case where the specified height (H) is lower than that of the tape center, but the tape 2 is pulled out from the cassette 1 and is wound around the traveling system of the mechanism portion by a predetermined amount. When a stable tension is not applied to the tape 2 during the loading operation, the reverse unloading operation, or when switching the tape running direction, as shown in FIG. 5, the tape 2 moves toward the center of the cassette 1. There is a slack or deviation between the upper and lower flanges of the supply reel 3 in one direction.
At this time, in the supply side optical path 15, as shown in FIG. 6, the reflected light 17 from the lower reel flange 11 of the upper and lower reel flanges 11 and 12 passes through the prism 7 and is received by the light receiving portion 8. Although it is not the end of the tape, it is detected as the end of the tape, which causes a problem in the system of the magnetic recording / reproducing apparatus.

[0006]

The present invention provides means for solving these problems, and the invention of each claim constitutes the following technical means. A first technical means is a light emitting portion arranged at a side of an optical path forming hole portion of a cassette loaded at a predetermined position, and light emitted from the light emitting portion arranged in a tape detecting hole portion of the cassette. A light guide for guiding the light guided to the light guide and a light receiving section for detecting the light guided to the light guide. The light from the light emitting section passes through the tape end and is guided to the light guide to receive the light. In the tape end detecting device for detecting the tape end by being received by the section, the optical path from the light emitting section to the light guide is inclined at a predetermined angle with respect to the cassette reference plane, and thus, It is possible to reduce the amount of light emitted in the direction that is disadvantageous in detecting the light from the light emitting part and reduce the amount of light reflected from the reel flange, and to make a tape edge detection device that does not cause malfunctions. And

A second technical means is the tape end detecting device of the first technical means, characterized in that the light guide is a prism. Therefore, the light guide can be made compact and highly accurate. Thus, it is possible to facilitate the assembling work at a predetermined position on the cassette loading surface.

A third technical means is the tape end detecting device according to the first or second technical means, in which the incident surface of the light guide is in the tape detecting hole of the cassette from the tape reel flange. It is characterized in that it is provided at a height outside the range of the reflected light path of once, thus eliminating the influence of the reflected light from the tape reel flange having a relatively large amount of light and causing no malfunction. The tape end detecting device can be used.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the embodiments shown in FIGS. FIG. 1 is a schematic plan sectional view showing a state in which a cassette is loaded in a tape end detecting device according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. The numbers in the figure correspond to those in the conventional example. Also, as in the conventional example, the height (H) of the optical path forming hole provided in the cassette defined by the cassette format is
It shows the case where the tape is offset downward from the tape center.

In FIG. 1, as in the conventional example, LE is provided on the side of the supply side and winding side optical path forming holes 9 and 10 of the cassette 1 loaded at the cassette loading position of the mechanism section.
Supply side and winding side light emitting sections 5 and 6 made of D are arranged, and the supply side and winding side optical paths 15 and 16 of the light emitted from these light emitting sections 5 and 6 toward the inside of the cassette 1 are
Supplying the cassette 1 and being guided to the incident surface of the prism 7 arranged in the tape detecting hole portion 13 provided in the middle of the reels 3 and 4, the cassette directly below the prism 7 is reflected by the reflecting surface 14. The light is received by the light receiving element 8 installed on the loading surface. The tape 2 supplied from the supply reel 3 intersects in the middle of one supply side optical path 15, and the tape 2 wound on the winding reel 4 intersects in the middle of the other winding side optical path 16. .

In the tape end detecting device of this embodiment, as shown in FIG. 2, the supply side optical path 15 from the supply side light emitting section 5 to the prism 7 is formed at a predetermined angle (θ: The upper surface of the reel flange 1 on the flat cross section of the supply-side optical path 15, which has been a problem in the conventional example, is configured by inclining (upward in FIG. 2) and reducing the amount of light emitted downward.
It is possible to reduce the amount of light reflected from the lower reel flanges 11 and 12 of the lower reel flange 11.
It is possible to reduce the amount of reflected light from the light guided to the incident surface of the prism 7 and reduce the possibility of malfunction.

Further, as the number of reflections of the reflected light increases, the amount of light on the reflected light path is attenuated. Therefore, the incident surface of the prism 7 disposed in the tape detecting hole 13 is set to the cassette 1
In the tape detecting hole 13 of the reel flange 11,
An optical path from the light emitting section 5 to the light receiving section 8 is arranged at a height deviating from the reflected light path ranges 18 and 19 from once, and the inclination angle θ of the optical path 15 and the angle of the reflecting surface 14 of the prism 7 are set. With the configuration of 15, it is possible to remove the influence of the reflected light having a relatively large light amount once. Since the structure on the winding side is symmetrical to the structure on the supply side, description thereof will be omitted. In the above embodiment, the prism 7 is used to form the light guide body that deflects the light emitted from the light emitting portions 5 and 6 on the supply side and the winding side so as to be guided to the light receiving portion 8 installed on the loading surface of the cassette. Although shown, it is not limited to the prism 7, and may be formed by a mirror, an optical fiber, or the like.

[0013]

As described above, the tape end detecting device for a cassette tape according to the present invention does not have a reflected light blocking means in the cassette as in the prior art, so that it is not necessary to secure a space for the tape. The edge detection device can be downsized.

Further, by tilting the optical path from the light emitting portion to the prism with respect to the cassette reference surface (bottom surface) by a predetermined angle, the amount of light emitted in the disadvantageous direction is reduced and the amount of light reflected from the reel flange is reduced. Therefore, it is possible to provide a tape end detecting device that does not cause a malfunction.

Further, since the incident surface of the light guide or the prism is provided in the cassette detecting hole at a height outside the one path of the reflected light from the reel flange, it has a relatively large light quantity. It is possible to eliminate the influence of the reflected light once, and it is possible to provide a tape end detection device that does not cause a malfunction.

The tape end detecting device of the present invention is useful for a magnetic recording / reproducing device using a cassette defined by any cassette standard, and is stable without being affected by the reflected light from the reel flange. In addition, the tape end can be detected with high accuracy.

[Brief description of drawings]

FIG. 1 is a schematic plan sectional view showing a state in which a cassette is loaded in a tape end detection device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a schematic plan sectional view showing a state in which a cassette is loaded in the conventional tape end detecting device.

FIG. 4 is a sectional view taken along line BB of FIG.

5 is a schematic plan sectional view for explaining the problem of FIG.

6 is a cross-sectional view taken along the line CC of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cassette, 2 ... Tape, 3 ... Supply reel, 4 ... Winding reel, 5 ... Supply side light emitting part, 6 ... Winding side light emitting part, 7 ... Prism, 8 ... Light receiving part, 9 ... Supply side optical path formation Hole portion, 10 ... Winding side optical path forming hole section, 11 ... Lower reel flange, 12 ... Upper reel flange, 13 ... Tape detecting hole section, 14 ... Reflecting surface, 15 ... Supply side optical path, 16
... Winding side optical path, 17 ... Reflected light, 18, 19 ... One reflected light path range.

Claims (3)

[Claims] 1. A light emitting portion disposed on a side of an optical path forming hole portion of a cassette loaded in a predetermined position, and light emitted from the light emitting portion disposed in a tape detecting hole portion of the cassette is loaded into the cassette. It is composed of a light guide body guided in the plane direction and a light receiving section for detecting the light guided to the light guide body, and the light from the light emitting section passes through the tape end and is guided to the light guide body to the light receiving section. A tape end detecting device for detecting the tape end by receiving light, wherein an optical path from the light emitting portion to the light guide is tilted at a predetermined angle with respect to a cassette reference plane. . 2. The tape end detection device according to claim 1, wherein the light guide is a prism. 3. The incident surface of the light guide is provided at a height outside the range of the reflected light path once from the tape reel flange in the tape detection hole of the cassette. The tape end detection device according to claim 1 or 2.