JPH03209651A - Magnetic recording and reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a VTR capable of detecting the start and end of a magnetic tape even when light emitting diodes for detecting the start and end of the magnetic tape are provided outside the cassette.

2. Description of the Related Art A magnetic tape start/end detection technique for a consumer VTR will be explained using FIGS. 2 and 3 using conventional VH5 and VHS-C format VTRs as examples.

In FIG. 2, light 10a emitted from a light emitting diode 10 provided on the chassis of the VTR passes through a light guide tube or light path 21 provided inside a standard-sized VHS cassette 20 attached to the VTR. The magnetic tape 22 is reached. At the beginning and end of the magnetic tape 22, there is a transparent tape (hereinafter referred to as a leader section) coated with no magnetic material. When the tape reaches the leader section, the light 10a of the light-emitting diode 10 becomes a photo Detected by transistor 11, the VTR stops running the tape.

Next, with reference to FIG. 3, a technique for detecting the beginning and end of a magnetic tape of a VTR capable of recording and reproducing a small-sized VHS-C cassette will be explained. The VH9-C cassette does not have a tube 21 for conducting the light emitting diode output like the VHS cassette. Therefore, the light emitting diode 10 is located outside the cassette 30. The output light 10a of the light emitting diode 10 is diverged as shown in FIG. 3, and when a portion of the light reaches the transparent leader portion of the tape, it is detected by the phototransistor 11.

Problems to be Solved by the Invention However, in the configuration shown in FIG. 3, the output light 10a of the light emitting diode 10 is diverging, so it is reflected by parts inside the VTR, such as the rotating cylinder 12, and the leader section of the magnetic tape is The reflected light 1ob reaches the phototransistor 11 even though it is not near the phototransistor 11, causing a malfunction (tape stopping). This problem arises because the detection power of the phototransistor 11 is different in level between the reflected light 1Qb and the output 10a of the light emitting diode 11 when it reaches the tape gluer section.
This can be solved by lowering the detection sensitivity of the phototransistor 10 so as not to respond to the reflected light 10b, but the detection range of the phototransistor 11 becomes smaller, and variations in the characteristics of optical elements such as the light emitting diode 1o and the phototransistor 11 and There is no margin for variations in the light transmittance of the leader section of the magnetic tape, and it is conceivable that word motion is more likely to occur, making mass production difficult.

Means for Solving the Problems The magnetic recording/reproducing apparatus of the present invention is one in which a light emitting diode for detecting the beginning and end of a magnetic tape is provided outside the cassette. It is equipped with a pipe that has the same diameter as the lens section of the phototransistor.

Function: The magnetic recording/reproducing device of the present invention is provided with a pipe having the same diameter as the lens in front of the phototransistor for detecting the beginning and end of the magnetic tape, so that the output of the light emitting diode is connected to the optical part of the vTR17 part. The amount of light reflected by the magnetic tape and incident on the phototransistor can be significantly reduced, and it is possible to prevent malfunctions caused by reflected light to the components other than the leader section of the magnetic tape.

Embodiment Hereinafter, a magnetic recording/reproducing apparatus according to an embodiment of the present invention will be explained with reference to the drawings.

As shown in FIG. 1, a light emitting diode 10 is placed outside a VHS-C case 30. Also light emitting diode 1o
A pipe 13 having the same diameter as the lens of the phototransistor is provided in front of the phototransistor 11 for detecting the output light 1oai. In order to prevent the reflected light 10b of the output light from the light emitting diode 1o from entering the phototransistor 11 by the components inside the VTR, the pipe 13 is made as long as possible, and its cross section is made to be in close contact with the light receiving surface of the phototransistor 11, and the other end is made to be as long as possible. should be placed as close to the magnetic tape as possible. With the above configuration, the amount of reflected light 10b detected by phototransistor 11 can be significantly reduced.

In the above embodiment, only the pressure on the supply side of the magnetic tape was explained, but the structure of the present invention can also be applied to the winding side, and has the same effect. Further, the present invention is applicable not only to a VTR capable of recording and reproducing VH8-C cassettes, but also to a VTR capable of recording and reproducing both a VHS cassette and 1 (S-C cassette) by attaching them to the same mechanism.
The same effect can be achieved in both cases.

Effects of the Invention As described above, the magnetic recording/reproducing apparatus of the present invention has a pipe having the same diameter as the lens in the front part of the transistor for detecting the beginning and end of the magnetic tape.
It is possible to significantly reduce the influence of reflected light from components inside R, and expand the detection range of the phototransistor.

Therefore, there is greater margin for variations in the characteristics of optical elements such as light emitting diodes and phototransistors, and variations in the light transmittance of the leader section of the magnetic tape, and the occurrence of malfunctions can be suppressed and reduced. Furthermore, f)) There is no need to provide a circuit for adjusting the detection level of the transistor and its work process, making it possible to mass-produce the device at low cost.

[Brief explanation of drawings]

FIG. 1 is a top view showing one embodiment of the present invention, FIG.
The figure is a top view illustrating a conventional magnetic tape start/end detection method. 10...Light emitting diode, 11...Phototransistor, 13...Pipe.

Claims (1)

[Claims] Light-emitting diodes for detecting the beginning and end of the magnetic tape are arranged outside the cassette tape, and a pipe having the same diameter as the lens of the phototransistor is provided in front of the phototransistor for receiving light. magnetic recording and reproducing device.