JPS5923020B2 - How to detect tape entanglement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape winding detection method for detecting that a tape is wound around a capstan or a pinch roller during recording or reproduction.

Winding the tape not only damages the tape, but also, if the tape is a cassette, makes it impossible to remove the cassette from the tape recorder. Therefore, a conventionally known method for detecting this type of tape winding is to detect the direction of rotation of the reel stand, detect that one take-up reel stand rotates in the opposite direction due to the winding, and detect that the mechanism There is a way to stop it. However, this method uses a DC generator to detect the rotation of the reel stand, which has disadvantages such as high cost and large equipment due to the generator, and a constant load on the reel stand. existed.
This invention was made in view of the above points, and its purpose is to convert a value obtained by converting the rotational speed of a reel stand into an electrical signal, and a value obtained by passing this value through a low-pass filter. Since entrainment detection is performed by comparison, a simple rotation detection means can be used without using a generator etc. Therefore, the configuration is simple and can be manufactured at low cost, and the detection means is small, as well as an auto-reverse type. An object of the present invention is to provide a method for detecting tape entrainment, which can also detect entrainment in a tape recorder.

Hereinafter, means for implementing the method of the present invention will be explained based on a first block diagram. In FIG. 1, 1 is a supply reel stand, 2 is a take-up reel stand, and 3 and 4 are known means for detecting the rotational speed of both reel stands, such as a photocoupler,
It consists of a combination of a magnet and a reed switch.

And rotation speed detection means 3 in the supply reel stand 1 and the take-up reel stand 2 when a 30-minute cassette tape is used.
, 4 are the output waveforms 3 and 4 in FIG. 5 is an adder that shapes the pulses from the rotation speed detection means 3 and 4 and removes noise, then adds both pulses and counts at fixed time intervals, and the output waveform is 5 in Fig. 2. .

6 is a D-A converter for converting the digital output from the adder 5 into an analog value; 7 is a low-pass filter that absorbs, or integrates, sudden changes from the converter 6; 8;
is a comparator that sends out an output when the output from the converter 6>low-pass filter 7 and stops the mechanism at the output.

Note that the low-pass filter 7 assumes that, for example, if winding is performed for 11 seconds, the running speed of the tape will change twice, and the maximum change during steady running is 0.3% for a 90-minute tape.
only occurs.

Therefore, it is designed to allow up to 10% of the change due to entrainment to pass through. Next, to explain the operation of the present invention, during steady running, the output from the converter 6 and the output from the low-pass filter 7 are compared by the comparator 8. Since the output is during running, the output from the low-pass filter 7 is the same as the output from the converter 6, so no output is sent from the comparator 8.

Next, assume that the tape is wound around the capstan due to charging of the capstan or the take-up reel stand stopping midway.

At the beginning of winding, the take-up reel stand 2 stops rotating,
Then it starts rotating in the opposite direction. Although the diameter of the capstan is originally small, it immediately increases as the tape is wound around it, and the actual running speed of the tape increases accordingly. Therefore, the rotation speeds of the supply and take-up reel stands 1 and 2 increase, so when the take-up reel stand 2 stops, one input terminal of the comparator 8 has a signal corresponding to the rotation speed of both reel stands 1 and 2. A value greater than that during steady running of the proportional sum is input, and the output from the low-pass filter 7 is input to the other input terminal. Here, since the output from the low-pass filter 7 is an integrated value, it is the value before tape winding, and therefore the value from the low-pass filter 7 is the value from the converter 6. As a result, an output is sent from the comparator 8, and by using this output to stop the mechanism or issue an alarm, the owner can be informed that the tape has become entangled. In the above embodiment, since the converter 6 outputs a value that is the sum of the rotational speeds of the supply reel stand 1 and the take-up reel stand 2, in the case of an auto-reverse type tape recorder, Winding of the tape can be detected, but if the number of revolutions of only one reel stand is detected, winding of the tape can be detected in that direction.

That is, when only the take-up reel stand 2 is detected by the rotation speed detection means 4, the output is converted into analog and directly sent to the comparator 8.
The signal is inputted to one input terminal of the filter, and is inputted to the other input terminal via the low-pass filter 7. When the tape is wound here, the number of revolutions of the take-up reel stand 2 suddenly increases, so that the value from the converter 6 is greater than the value from the low-pass filter 7, and tape winding can be detected. Furthermore, in the above embodiment, the case where the value from the converter 6 increases in proportion to the rotation speed of the reel stand has been explained, but in the case where the value from the converter 6 increases in proportion to the rotation speed of the reel stand, the comparator 8 All you have to do is send the output when it is a value.

Furthermore, although the above embodiment describes the case where the tape is wound around the capstan, fluctuations occur in the rotation of the reel stand also when the tape is wound around the pinch roller, so winding is detected by an operation similar to that described above. It can be performed.

As described above, this invention inputs the value obtained by converting the rotational speed of the reel stand into an electrical signal and the converted value to a comparator via a low-pass filter, and sends out an output when a difference occurs between the two. Since it was determined that the circuit structure is simple and can be manufactured at low cost, it can be made smaller, and it is also possible to
When calculating the sum of the rotational speeds of two reel stands, an auto-reverse tape recorder can detect tape winding in both directions, and can also detect not only tape winding into the carburetor but also winding into the pinch roller. It has the effect that it can be done.

[Brief explanation of the drawing]

The figures show an embodiment for implementing the tape entrapment detection method according to the present invention, FIG. 1 is a block diagram for implementing this method, and FIG. 2 is a diagram showing the running state of the tape. . 1... Supply reel stand, 2... Take-up reel stand, 3, 4... Rotation speed detection means, 5...
... Adder, 6 ... Digital-to-analog converter, 7 ... Low-pass filter.

Claims (1)

[Scope of Claims] 1. Convert the rotation speed of the reel stand into an electrical signal, integrate the converted electrical signal via a low-pass filter, and compare the integrated output with the electrical signal using a comparator; A method for detecting tape entrainment, characterized in that it is determined that the tape has been entrained when a difference occurs between the values of . 2. The tape winding according to claim 1, wherein the electrical signal obtained from the rotation speed is a signal of the sum of the rotation speeds of the take-up and supply reel stands, and is an analog signal. Detection method.