JPH08190748A - Detecting structure of start and end of tape - Google Patents

Abstract

PURPOSE: To provide a detecting structure of start and end of a tape, with which the erroneous operation is prevented by increasing sensitivity of a photodetector and also the assemblage is facilitated by simplifying the structure. CONSTITUTION: An introducing hole 31a for introducing the light, an inserting hole 31b for inserting a holder 41, and a positioning hole 31c for positioning the holder 41 are provided on a box 31 consisting of an opaque member. A hook part 41b having elasticity, a bending part 41c bent to the nearly chevron state, and a reflection plate 42 are provided on the holder 41. The bending part 41c of the holder 41 is abutted on the inserting hole 31b and also the hook part 41b is engaged with the positioning hole 31c, then the holder 41 is fixed inside the box 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape beginning and end detecting structure used in a device using a tape as a recording medium.

[0002]

2. Description of the Related Art Conventionally, as a device for detecting the beginning and end of a tape, a light emitting element is provided at the center of the main body of the device, and light receiving elements are provided at both sides of the main body so that the light from the light emitting element is used as the beginning and end of the tape. The tape end is detected by hitting the tape for detecting the tape end provided on the light receiving element. For example, to detect the beginning and end of the tape on the tape deck,
There is one as shown in FIGS. A side wall 57a of the deck chassis 57 is provided with an auxiliary printed circuit board 53 for installing the light receiving element 52 at a position where the light emitted from the light emitting element 51 provided in the central portion of the chassis 57 of the tape deck 50 can be received.
Mounted on the light receiving element 52 on the auxiliary printed circuit board 53.
Is soldered, and the main printed circuit board 54 and the auxiliary printed circuit board 53 on the lower side of the deck chassis are connected by lead wires 55.

As another example, as shown in FIG. 6, there is a prism cylindrical body 56 made of a transparent resin such as acrylic resin and provided with an inclined surface 56a. The light beam from the light emitting element 51 is introduced into the prism cylinder 56, reflected by the inclined surface 56a, guided to the lower end surface of the prism cylinder 56, and guided to the light receiving element 52 on the main printed circuit board 54 installed at this position. However, the light receiving element 52 receives light.

[0004]

However, in such a conventional tape detecting device for detecting the beginning and end of the tape, since the periphery of the light receiving element 52 is open, not only the light ray from the light emitting element 51 but also the external light is emitted. Also enters the light receiving element 52, and the amount of light rays entering the light receiving element 52 increases.
There was a defect that the sensitivity of No. 2 was lowered or malfunction was caused.

Further, when the transparent resin prism cylinder 56 as shown in FIG. 6 is used, external light may be directly incident on the light receiving element 52. Therefore, the same problem as described above occurs. It was In addition, the position of the light receiving element 52 on the main printed circuit board 54 needs to be accurately aligned with the position of the prism cylinder 56, which makes it difficult to adjust the position of the prism cylinder 56.

The present invention has been made in order to solve the above problems, and uses an opaque member in the vicinity of a reflection plate for reflecting the light from the light emitting element to the light receiving element side and around the optical path to the light receiving element. By covering it, only the light from the light emitting element is received by the light receiving element to prevent sensitivity deterioration and malfunction of the light receiving element, and by simplifying the structure, it is easy to attach the reflector plate. It is intended to provide an edge detection structure.

[0007]

In order to solve the above-mentioned problems, according to the present invention, an introduction hole for introducing light, an insertion hole for inserting a holder, and the holder are positioned in a box made of an opaque member. The holder is provided with an elastic hook portion, a bent portion formed in an end portion of the holder and bent into a substantially V shape, and a reflection plate. The hook portion engages with the positioning hole and the holder is fixed inside the box while the portion abuts the insertion hole.

[0008]

By attaching the holder having the reflecting surface to the box, the light from the light emitting element which has passed through the prism can be refracted and guided to the light receiving element. Moreover, since the circumference of the optical path to the light receiving element is covered by the cylindrical body,
Only the light of the light emitting element is guided to the light receiving element.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are views showing an embodiment of a structure for detecting the end and beginning of a tape in a tape deck of the present invention. In the figure, 1 is a deck chassis having a rectangular shape in plan view, 2 is a rotatable head cylinder to which a recording / playback head and the like are attached, and 3 and 4 are erected on slide bodies 7 and 8 which slide and guide via rails 5 and 6. Then, the tape loading pins 10 and 11 for winding the magnetic tape 9a of the video cassette 9 around the head cylinder 2 are supply and take-up reel shafts for axially supporting the tape reel of the cassette 9, and 12 is an audio signal. An input / output head, 13 is an erasing head, 14 is a capstan, and 15 is a pinch roller.

Further, in the figure, 16 is a cassette holder for supporting the cassette 9, 17 and 17 are erected on the upper surface of the chassis 1, and the cassette holder 16 is movably attached to an insertion / removal position of the cassette 9 or a recording / reproducing apparatus. Left and right guide plates, 19 is a tape running motor (flywheel) for rotating the capstan 14, and 20 is a loading motor for driving a tape loading lever, cassette loading gears 22, 22 and the like (not shown),
The loading motor 20 causes the loading lever to slide to reciprocate the loading pins 3 and 4, and the loading motor 20 causes the loading gears 22 and 22 to rotate in the forward and reverse directions.
6 is configured to reciprocate.

Below the deck chassis 1, there is provided a printed circuit board 23 for forming a recording / reproducing circuit, a motor control circuit, etc., as shown in FIG.
3 is fixed to the lower surface of the chassis 1 with screws 24, and a light emitting diode 25 which is a light emitting element and phototransistors 26 and 26 which are light receiving elements are directly fixed to the substrate 23.

A central prism 27 made of acrylic resin in the shape of a quadrangular prism is provided, and the central prism 27 is attached to the chassis 1 by a hook 28 provided by insert molding.
Is locked and fixed, the lower end surface of the central prism 27 is arranged so as to face the light emitting diode 25, and the left and right anti-slopes 29 and 30 are formed at the upper end of the central prism 27. The light from the light emitting diode 25 is configured to be emitted to both sides via the light.

Further, substantially box-shaped boxes 31 and 31 formed of a non-translucent member are provided on the optical paths of the light emitted to both sides by the central prism 27. The box 31 includes an introduction hole 31a for introducing light from the light emitting diode 25, an insertion hole 31b for inserting a holder 41 described later, a positioning hole 31c for positioning the holder 41 together with the insertion hole 31b at a predetermined angle,
The holder 41 includes a square hole 31d for attachment / detachment and a guide plate 31e for fixing the box 31 on the deck chassis 1.

Further, a U-shaped slit 41a is formed in the holder 41, a hook portion 41b is formed in the slit 41a, and one end of the holder 41 is bent in a substantially V shape. A bent portion 41c is formed.
A reflector 42 is fixed to the side opposite to the side where the hook 41b is provided. Here, the reflector 42 is
A tape capable of reflecting light, a metal film, glass, or the like is used.

When the holder 41 is attached to the box 31 in the structure for detecting the beginning and end of the tape thus constructed, the holder 41 is inserted into the insertion hole 31b of the box 31.
When it is inserted further obliquely upward, the tip of the holder 41 enters the positioning hole 31c. And further holder 4
When 1 is continuously inserted, the tip of the hook portion 41b protruding from the upper surface of the holder 41 comes into contact with the edge of the positioning hole 31c. Here, when the holder 41 is further pushed in, the end portion 41d of the hook portion 41b comes into contact with the edge of the positioning hole 31c on the side of the square hole 31d, and at the same time, the bent portion 41d of the holder 41 comes into contact with the box 31 and the box 31 moves to the box 31. The holder 41 is fixed.

As described above, the holder 4 is attached to the box 31.
By fixing 1, the reflection plate 42 is mounted in the box 31 with a predetermined angle. by this,
The mounting is considerably easier than the conventional mounting of the reflection plate 42, and the structure can be simplified. Furthermore, the reflector 42
It becomes easy to adjust the angle.

The operation of the above configuration will be described. The light emitted from the light emitting diode 25 is the central prism 27.
The light enters from the lower end surface of the light source and is emitted to both sides by the reflecting surfaces 29 and 30 on the left and right of the upper end portion. Then, the light that has passed through the tape 9a in the video cassette 9 enters the box 31 through the introduction hole 31a provided in the box 31, and the light that enters the box 31 has a reflection plate provided in the holder 41. Refracted by 42, phototransistor 26
Be led to.

Particularly, in the present invention, the reflection plate 4 for refracting the light from the light emitting diode 25 toward the phototransistor 26 side.
2 and the circumference of the optical path to the phototransistor 26 are covered with a box 31 made of an opaque member, so that only the light from the light emitting diode 25 is phototransistor 2.
Since 6 receives the light, it is possible to prevent a decrease in sensitivity and eliminate a malfunction.

[0019]

As described above in detail, according to the present invention, since the light receiving element can receive only the light from the light emitting element, the sensitivity of the light receiving element can be increased, malfunctions can be prevented, and the structure is simple. It is possible to make the reflection plate easy to attach. Furthermore, it is possible to easily adjust and replace the reflector.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing an entire apparatus which is an embodiment of the present invention.

FIG. 2 is a sectional view of the embodiment.

FIG. 3 is a perspective view of a box and a holder in the above embodiment.

FIG. 4 is a schematic plan view showing an entire conventional device.

FIG. 5 is a cross-sectional view showing a main part of a conventional device.

FIG. 6 is a cross-sectional view showing a main part of another conventional device.

[Explanation of symbols]

 25 light emitting element 26 light receiving element 27 prism 31 box 31a introduction hole 31b insertion hole 31c positioning hole 41 holder 42 reflector

Claims (1)

[Claims] 1. A box made of an opaque member is provided with an introduction hole for introducing light, an insertion hole for inserting a holder, and a positioning hole for positioning the holder, and the holder is provided with elasticity. A hook portion, a bent portion formed in an end portion of the holder, which is bent in a dogleg shape, and a reflector are provided, and the bent portion of the holder contacts the insertion hole and the hook portion is positioned. A structure for detecting the beginning and end of a tape, wherein the holder is fixed inside the box by engaging with a hole.