JPH0411232Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape end detection device for detecting the end of an operating tape in a cassette tape recorder or the like.

[Prior art]

Traditionally, in cassette tape recorders,
A common means for detecting the end of a tape during recording/playback or fast-forwarding is to detect fluctuations in tension torque when the tape reaches its end. However, with this method, the end of the tape is detected only after the recorded part (magnetic part) of the tape passes the head and the non-recorded part, such as the transparent tape at the end, contacts the head. This means that it cannot be used with auto-reverse type tape recorders.

Therefore, an optical sensor type device has been devised as a tape end detection device for realizing this quick auto reverse. 1 and 2 show a conventional example of an optical sensor type tape end detection device.

The one shown in Fig. 1 is a light transmission guide 2 formed of acrylic or the like on the detection end surface of a photoreflector 1.
and a light receiving guide 3 are arranged in series.
The end faces 2a and 3a of both guides 2 and 3 are placed side by side with the magnetic head of a tape recorder, and the changes in the reflectance of the detected light when it moves from the recording part (magnetic part) to the non-recording part of the tape are measured optically. By detecting the end of the recorded portion, the end of the recorded portion can be detected. However, in this method, since the light transmitting guide 2 and the light receiving guide 3 are molded from acrylic or the like, there is a drawback that the transmittance of the detection light is low and the light loss is large. In addition, as shown in FIG. 1, since the light transmitting and light receiving guides 2 and 3 are close to each other, a shielding member 4 made of black paint or a metal plate is used to prevent crosstalk between them.
This increases the number of parts and complicates assembly work.

Next, what is shown in FIG. 2 is an improved version of the cassette positioning pin 5 provided in the tape recorder, and a light emitting element 6 and a light receiving element 7 are disposed in the midsection thereof. When loading the cassette 10 into a tape recorder, positioning is performed by inserting the positioning pin 5 through the positioning hole 10a. It's summery. and,
When the tape T runs, the boundary between the recorded portion and the non-recorded portion is detected by the light receiving element 7. However, in this method, the positioning pin 5 must be specially created, and the light emitting element 6 and the light receiving element 7 must be placed inside the thin pin.
Since it has to be stored, processing and assembly are complicated and costs are high.

[Purpose of this invention]

The present invention was developed by focusing on the above-mentioned conventional problems, and has a simple structure that allows the light transmitting and receiving ends to be reliably opposed to the tape, while reducing the loss of light. The purpose of the present invention is to provide a tape end detection device that enables highly accurate detection.

[Means for solving problems]

The tape end detection device according to the present invention includes a light transmitting element that emits detection light, a first light guide path that guides the light from the light transmitter to the tape surface, and a light guide path that guides the light from the first light guide path through the tape surface. a second light guide path that guides the reflected light; a light receiving element that receives the light guided by the second light guide path and converts it into an electrical signal; A tape regulating plate is provided which slides into contact with the tape and keeps the distance between each end face of the first and second light guide paths and the surface of the tape constant.

[Effect]

In the above means, the detection light emitted from the light transmitting element is sent to the tape from the first light guide path, and the reflected light is guided to the light receiving element through the second light guide path. Further, a tape regulating plate protrudes in the tape direction from a holding member that holds the light guide, and the tape slides on this tape regulating plate, so that the distance between the end face of each light guide and the tape is kept constant. Furthermore, since the tape does not directly slide on the end surface of the light guide path, it is possible to prevent the optical characteristics of the end surface of the light guide path from deteriorating due to adhesion of magnetic powder or the like.

[Example of the present invention]

Next, an embodiment of the present invention will be described with reference to FIG. 3 and the following drawings.

FIG. 3 shows a tape end detection device 20 according to the present invention.
4 is an exploded perspective view of the tape end detection device 20, FIG. 5 is a partially cutaway plan view showing the tape end detection device 20 facing the tape T, and FIG. 6 is a perspective view showing the tape end detection device 20. The figure is a side view showing the positional relationship between the tape end detection device 20 and the tape T.

The case of the tape end detection device 20 is the outer case 2.
1 and an inner case 22, both cases 21 and 22 are molded from a material such as plastic. Legs 21a and 21b are integrally protruded from the lower surface of the outer case 21.
The tape end detection device 20 has these two legs 21a.
and 21b to be installed on the head base (not shown) of the tape recorder.
A square hole 21 is provided in the tape facing surface 21c of the outer case 21.
d is open, and a pair of tape guide plates 21e are protruded from the upper and lower ends of this square hole 21d so as to face each other at a constant interval in the upper and lower directions. The interval between the tape guide plates 21e is set to be slightly wider than the width of the tape T. Furthermore, a tape regulating plate 21f is provided protruding from the side edge of the square hole 21d. As shown in FIG. 6, this tape regulating plate 21f extends between the two tape guide plates 21e in a direction perpendicular thereto. Further, the tip of this tape regulating plate 21f is connected to the tape guide plate 2.
1e is slightly retracted toward the main body of the outer case 21, and the tape T is formed between this tape regulating plate 21f and the upper and lower tape guide plates 21e.
It has come to pass between.

Further, the inner case 22 has a thin rectangular tube shape at the front end 22a and a thick rectangular tube shape at the rear portion 22b. A photoreflector 23, which is a light transmitting/receiving element, is housed in this rear part 22b. This photoreflector 23 has an optical fiber 2 for transmitting light.
4 is connected to a light-receiving optical fiber 25, and both optical fibers 24 and 25 are housed in the tip 22a of the inner case 22. In addition, the inner case 22
After the optical fibers 24 and 25 of the photoreflector 23 are housed in the front part 22a and rear part 22b, a cover (not shown) may be fitted into the side opening of each part 22a and 22b.

The tip 22a of the inner case 22 is fitted into the square hole 21d of the outer case 21 from the rear. At this time, as shown in FIG.
It protrudes from the tape facing surface 21c and is exposed between the upper and lower tape guide plates 21e at a position slightly recessed toward the case body side than the tip of the tape regulating plate 21f.

On the other hand, as shown in FIG. 3, the cassette 10 has a pair of positioning holes 10a for positioning the cassette when loaded into a tape recorder, and capstan insertion holes 10b on both sides thereof. A reading window 10c for a head is opened on the front side of the cassette 10, and a head pad 11 is provided within this window 10c. The tape facing surface 21 of the tape end detection device 20 is placed on either of the small windows 10d formed on both sides of the reading window 10c.
c are facing each other. Moreover, a window 10e for driving by a pinch roller is formed further outside the small window 10d. A splicing tape Tb is connected to the end of the recording portion (magnetic portion) Ta of the tape T stored in the cassette 10, and a transparent tape Tc is further attached to this splicing tape Tb.
are installed in succession.

Next, the detection operation by the tape end detection device 20 will be explained.

When you load cassette 10 into a cassette tape recorder and press the play button or record button, the tape end detection device 20 on the head base detects cassette 1.
0 direction, the tape facing surface 21c of the outer case 21 approaches the small window 10d. At this time, the fifth
As shown in the figure, the tape guide plate 21e is connected to the small window 1.
0d, and the tape T comes to be located between the tape guide plates 21e (see FIG. 6). In addition, due to the presence of the tape regulating plate 21f,
The end face 24a of the light transmitting optical fiber 24 and the end face 25a of the light receiving optical fiber 25 come to face the tape T at a minute interval.

Light emitted from the light transmitting section of the photoreflector 23 inside the inner case 22 is transmitted through the light transmitting optical fiber 24, and is projected onto the surface of the tape T from its end surface 24a. Then, the reflected light enters the end face 25a of the light-receiving optical fiber 25, travels through the light-receiving optical fiber 25, and is detected by the light-receiving portion of the photoreflector 23.

When the end of the tape T being fed within the cassette 10 appears in the small window 10d, the tape end is detected from the difference in light reflectance between the recorded portion Ta and the other non-recorded portion Tb.

Based on this detection operation, the drive device in the tape recorder is switched, and the quick auto-reverse operation of the tape T is performed.

In addition, the splicing tape Tb is in cassette 1.
Depending on the type of 0, it may be made of silver paper, red tape, white tape, etc., or opaque tape may be used instead of transparent tape Tc, but no matter what type of tape is used, the recorded portion Ta and Non-recorded part
If Tb and Tc have different light reflectances, the end of the tape can be detected. Further, in the case of a metal tape, the reflectance is high in the recorded portion and low in the non-recorded portion, so that the end of the tape can be detected based on the difference in the detection output of the light receiving element.

[Effects of this invention]

According to the present invention, the tape regulating plate protrudes from the holding member that holds the first light guide path and the second light guide path in the tape running direction, and the tape slides on this tape regulating plate, so that the tip surface of the light guide path Not only can detection accuracy be maintained at a high level by keeping the distance between the tape and the tape at a constant level, but also because the tape does not slide directly onto the light guide path, it is possible to prevent magnetic particles from adhering to the end surface of the light guide path. It is possible to prevent the light guide function from being degraded due to adhesion of powder and the like, thereby preventing the optical detection accuracy from decreasing.

[Brief explanation of drawings]

1 and 2 are perspective views showing a conventional tape end detection device, FIG. 3 and the following show embodiments of the present invention, and FIG. 3 is a perspective view showing a cassette and a tape end detection device. FIG. 4 is an exploded perspective view of the tape end detection device, and FIG. 5 is a partially cutaway plan view showing the tape end detection device facing the tape.
FIG. 6 is a side view showing the tape end detection device facing the tape. 10...cassette, 10d...small window for tape detection, T...tape, Ta...recording part, Tb,
Tc...Non-recording portion, 20...Tape end detection device, 21...Outer case, 22...Inner case, 21
c...Tape opposing surface, 21e...Tape guide,
21f...Tape regulation plate, 23...Light transmitting/receiving element,
24... Optical fiber for light transmission, 24a... End face, 2
5... Optical fiber for light reception, 25a... End face.

Claims (1)

[Scope of utility model registration request] A light transmitting element that emits detection light, a first light guiding path that guides the light from the light transmitting element to the tape surface, and a second light guiding path that guides the reflected light that is emitted from the first light guiding path and passes through the tape surface. a light-receiving element that receives the light guided by the second light guide and converts it into an electrical signal; 1. A tape end detection device comprising: a tape regulating plate that maintains a constant distance between each end face of the light guide path and the surface of the tape.