JPH08249760A - Light transmission type optical sensor - Google Patents

Abstract

PURPOSE: To obtain a light transmission type optical sensor capable of surely and safely detecting a tape end, etc., effectively simplifying the constitution and realizing a cost reduction. CONSTITUTION: Light emitting elements 5, 6 and light receiving elements 7, 9 are installed onto stationary main chassis 2 and light quantity changing parts 15a, 15b are set on sliding chassis 3 movable relative with the main chassis 2. This optical sensor is so constituted that photodetection is executed between the light emitting elements 5, 6 and the light receiving elements 7, 9 in an optical path formed to pass these light quantity changing parts 15a, 15b. The respective optical paths from the light quantity changing parts 15a, 15b to the light emitting elements 5, 6 and the light receiving elements 7, 9 are partly made parallel with the sliding direction of the sliding chassis 3 in the air. The total optical path length of these parallel optical paths is set constant and is larger than the sliding quantity of the sliding chassis 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording or reproducing apparatus in which a chassis for mounting reels is slid, and more particularly to a structure for detecting tape end and reel stand rotation.

[0002]

2. Description of the Related Art In a magnetic recording or reproducing apparatus of this kind, a tape end or the like is detected, for example, optically. The detection element is provided at an appropriate place on the slide chassis or the main chassis. In the case of the one provided on the slide chassis, for example, the light emitting / receiving element is arranged at a predetermined position on the slide chassis, and the tape end or the like can be detected by an optical signal passing through an optical path formed there. Further, in the case where such a light emitting / receiving element is provided in the main chassis, the detection element is arranged so as to correspond to a predetermined position (recording or reproducing position) of the slide chassis, and the tape in the tape cassette moved to that position. On the other hand, the tape end or the like is detected.

[0003]

However, when the detection element is provided on the slide chassis side, wiring for the mode detection switch and the like is provided on the main chassis. It will span. Then, there are problems that the wiring structure becomes complicated and the assemblability is deteriorated, and as a result, the cost is increased.

Further, when the detecting element is provided on the main chassis side, the optical path formed by the detecting element is dedicated to the recording or reproducing position. Therefore, when the cassette is mounted, the tape end and the reel are rotated during the slide. Can not be detected. For this reason, the length of the tape that can be pulled out from the cassette cannot be grasped, so that it is impossible to fix only one reel and to perform loading, and in this case, for example, both reel-free loading operations are unavoidable. Then, there arises such a disadvantage that the tape position is displaced before and after the cassette is attached and detached. Further, it is difficult to detect a reel winding failure during unloading, and there is a risk that the cassette is ejected even if there is an unrolled tape. In this case, there is a problem that the tape is damaged.

In view of the above situation, it is an object of the present invention to provide a light guide type optical sensor capable of safely and surely detecting the tape end and the like and effectively realizing the simplification of the structure and the cost reduction. To do.

[0006]

In the light guide type optical sensor of the present invention, a light emitting element and a light receiving element are installed on a fixed main chassis, and a quantity of light is placed at a proper position on a slide chassis movable with respect to the main chassis. While setting the changing part,
An optical path formed so as to pass through the light amount changing portion is configured to perform light detection between the light emitting element and the light receiving element, and each optical path from the light amount changing portion to the light emitting element and the light receiving element. Is made parallel to the slide direction of the slide chassis in the air, and the total optical path length of these parallel optical paths is constant and is larger than the slide amount of the slide chassis.

[0007]

According to the present invention, the light emitting element and the light receiving element are provided on the main chassis, and the light amount changing portion is provided on the slide chassis, respectively, and the light amount changing portion and the light emitting element are provided between the light amount changing portion and the light receiving element. Part of each optical path is parallel to the sliding direction of the slide chassis in the air. By setting the optical path in this way, when the slide chassis moves, the optical path length can always be kept constant regardless of the position of the slide chassis. Therefore, when the cassette is mounted, the tape end and the like can be accurately detected even during the slide.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the light guiding optical sensor according to the present invention will be described below with reference to FIGS.

FIG. 1 shows the state of the magnetic recording or reproducing apparatus according to the present invention when the cassette is detached or not mounted. In the figure, 1 is a rotary drum including a recording head, 2 is a main chassis on which the rotary drum 1 is mounted, 3 is a slide chassis on which a cassette (not shown) is mounted, and elongated holes 3a to 3d thereof are planted in the main chassis 2. It is engaged with the standing pins 2a to 2d, respectively. The slide chassis 3 can be slid by a distance L in the direction of the rotary drum 1 by a mechanism (not shown) during recording or reproduction.
Reference numeral 4 denotes a take-up reel stand rotatably supported on the slide chassis 3, and the surface of the take-up reel stand 4 on the side of the slide chassis 3 reflects in the rotation direction along the outer circumference.
A non-reflective surface is formed.

Reference numerals 5 and 6 denote light-emitting diodes installed respectively on the main chassis 2 and the slide chassis 3, 7 denotes a supply side light receiving sensor installed on the main chassis 2, 8 denotes a winding side light receiving sensor, Reference numeral 9 is a light receiving sensor for reels. Further, 10 is a supply side light guide installed on the slide chassis 3, 11 is a winding side light guide, and 12 is a winding side light guide.
Is a light emitting light guide, 13 and 14 are slide chassis 3
The first and second reel light guides are installed above the main chassis 2 respectively.

Numeral 15 is a non-translucent tape in a cassette (not shown), which is so-called so that the vicinity of a reel hub (not shown) which engages with the reel stand has a certain length of transparency.
It is configured as a leader tape. Reference numeral 16 denotes a control circuit which causes the light emitting diodes 5 and 6 to emit light and detects the outputs of the light receiving sensors 7 to 9 so as to cooperate with the mode detection switch to perform operations such as reel rotation and chassis slide. It has become.

In the light guide type optical sensor constructed as described above, the light emitted from the light emitting diode 5 is reflected by the surfaces 12a and 12b of the light emitting light guide 12. At this time, the tape 15 in the light quantity changing portion is the leader tape 15a.
In this case, the light passing therethrough is further reflected by the surfaces 10a and 10b of the supply side light guide and reaches the supply side light receiving sensor 7. In addition, the tape 1 in the light quantity changing portion
If 5 is a magnetic tape, the light is blocked between the surface 12b and the surface 10a by the magnetic tape and is not received by the supply side light receiving sensor 7.

Light emitting diode 5 and light emitting light guide 1
Between 2, the supply side light guide 10 and the supply side light receiving sensor 7
The distances between them are L ₁ and L ₂ , respectively, and their optical path directions are parallel to the sliding direction of the slide chassis 3, and L <L <
It is L ₁ + L ₂ . This relationship is based on the light emitting diode 5, surface 12a, surface 12c, leader tape 15b, surface 11
The same applies to the winding-side optical path that passes through a, the surface 11b, and the winding-side light receiving sensor 8.

Next, the light emitted from the light emitting diode 6 is reflected by the surface 13a of the first reel light guide 13, passes through the hole 2e of the slide chassis 3, and is a light quantity changing portion of the take-up reel stand 4. Irradiate the reflective / non-reflective surface. When this is a reflecting surface, the reflected light passes through the hole 2e of the slide chassis 3 again, and the second reel light guide 14
The light is reflected by the surface 14a of the above and reaches the reel light receiving sensor 9. Further, when the take-up reel stand 4 has a non-reflective surface due to the rotation phase, the reel light receiving sensor 9 does not receive light.

The distances between the light emitting diode 6 and the first reel light guide 13 and between the second reel light guide 14 and the reel light receiving sensor 9 are L ₃ and L ₄ , respectively, and their optical paths are the same as the sliding direction of the slide chassis 3. They are parallel and L <L ₃ + L ₄ . In the left half (supply side) of the chassis, the configuration corresponding to the light emitting diode 6, the first reel light guide 13, the take-up reel stand 4, the second reel light guide 14 and the reel light receiving sensor 9 is the same as above. It is configured.

According to the above construction, the slide chassis 3 is moved from the position shown in FIG. 1 when the cassette is attached or detached to the position shown in FIG.
The optical path length from the light emitting diode 5 to the supply side and winding side light receiving sensors 7 and 8 is always constant regardless of the position up to the position. It is possible to detect the light transmission / non-light transmission of the tape 15, that is, the leader tape / magnetic tape in the vicinity of the reel hub joint portion, and the optical path length from the light emitting sensor 6 to the reel light receiving sensor 9 is constant, and the winding ( Supply) The control circuit 16 can detect the change of the reflection / non-reflection surface due to the rotation of the reel base 4, that is, the rotation of the reel base.

[0017]

As described above, according to the present invention, it is possible to perform slide and tape loading while determining whether or not there is a drawable tape on the reel hub in the cassette and confirming the rotation of the reel base. By using the method of installing the discrimination hole detection switch on the main chassis together, all the elements and wiring boards conventionally installed on the slide chassis are integrated with the mode detection switch on the main chassis without impairing the detection function. can do. Therefore, it is possible to effectively reduce the number of parts and the number of assembly steps by eliminating expensive boards on the slide chassis and flexible connectors between mutually moving chassis, and it is possible to realize a significant cost reduction. And so on.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state of a magnetic recording or reproducing apparatus according to an embodiment of a light guide type optical sensor according to the present invention when a cassette is detached or not attached.

FIG. 2 is a perspective view showing a state in which a cassette is mounted in the magnetic recording or reproducing apparatus according to the embodiment of the light guide type optical sensor according to the present invention.

[Explanation of symbols]

 1 rotating drum 2 main chassis 3 slide chassis 4 winding reel stand 5 light emitting diode 6 light emitting diode 7 supply side light receiving sensor 8 winding side light receiving sensor 9 reel light receiving sensor 10 supply side light guide 11 winding side light guide 12 light emitting light Guide 13 First reel light guide 14 Second reel light guide 15 Tape 16 Control circuit

Claims (1)

[Claims] 1. A light emitting element and a light receiving element are installed on a fixed main chassis, and a light quantity changing section is set at a proper position on a slide chassis movable with respect to the main chassis, and the light quantity changing section is passed through the light quantity changing section. A light guide type optical sensor configured to perform light detection between the light emitting element and the light receiving element in an optical path formed in, each from the light amount changing unit to the light emitting element and the light receiving element. A part of the optical path is parallel to the sliding direction of the slide chassis in the air, and the total optical path length of these parallel optical paths is constant and is larger than the sliding amount of the slide chassis. Light guide type optical sensor.