JPS61178714A - Method for detecting rotary head clogging of magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To detect the clogging of a rotary head and a recording error at the time of clean join by providing a detecting period setting circuit which transmits the output of a comparator circuit only during a period when a detection position is not a reproduction signal switching position in terms of a comparator circuit acting period. CONSTITUTION:The detecting period setting circuit 7 connected between the comparator circuit 6 and a display device 8 sets a head switching signal as an input and limits the period when the output of the comparator circuit 6 is transmitted to the display device 8. Where a recording error occurs or the rotary head is blinded during a temporary stoppage period, the output (d) of an envelop detecting circuit 5 has a period when it is lower than a reference voltage V1, because a reproduced output cannot be obtained from the rotary head 1a or 1b. At this time, if the detecting position of the detecting period setting circuit 7 is any one of position tA-tC, a signal at a low level is transmitted to the display device 8 in a time tB. Although the comparator circuit 6 is acting, the display device 8 issues the alarm because of the low level of the output of the comparator circuit 6, and accordingly such a detection can be made that a recording error or the clogging of the rotary head occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Applicability The present invention is capable of rewinding a tape by a certain amount during splicing and then stopping the tape, and after canceling the pause, maintaining the playing state for a certain period of time.
This invention relates to a method for detecting clogging in a rotary head of a magnetic recording/reproducing apparatus by detecting a reproduction signal during the continuous shooting period of the magnetic recording/reproducing apparatus, which starts recording again after the phases of a reproduction control signal and a control signal of a recording signal match. be.

When splicing is performed in a conventional magnetic recording and reproducing apparatus, it is preferable that the spliced portion be reproduced without any screen disturbance. In particular, it has become an indispensable technology for magnetic recording and reproducing devices used for broadcasting, news reporting, etc.

However, when performing splicing, even though the rotating cylinder is rotating, the tape is not running and the rotating head is running over the same part of the tape, causing damage to the tape and the rotating head. There are problems such as clogging. Therefore, even if recording starts again, there is a possibility that recording will not be possible due to causes such as clogging of the rotating head, and recording errors may occur, especially in magnetic recording and reproducing devices for broadcasting and news reporting. For devices that do not allow this, it is important to confirm that the rotating head is in a recordable state after a temporary stop. Therefore, in recent years, during continuous shooting, the tape is rewound a certain amount and stopped, the playback state is maintained for a certain period after the pause is released, and the playback output from the rotating head is detected. We check to see if the rotating head is clogged during inspection and continuous shooting.

An example of a method for detecting clogging in the rotary head during the continuous shooting period of the above-described conventional magnetic recording/reproducing apparatus will be described below with reference to the drawings.

FIG. 5 is a block diagram showing a method for detecting clogging of a rotary head during a continuous shooting period in a conventional magnetic recording/reproducing apparatus.

1a and 1b are rotary heads, and during recording, the recording circuit 3
The flow of signals during recording and reproduction is controlled by recording/reproduction switching circuits 2a and 2b so that they are connected to the reproduction circuit 4 during reproduction. The reproduction signal amplified and switched by the reproduction circuit 4 is detected by an envelope detection circuit 6, and a comparison circuit 6 compares the detected voltage with a reference voltage. Furthermore, a display device 8 that operates according to the output of the comparator circuit 6 is connected to the comparator circuit 6, and when the detected voltage is lower than the reference voltage, the display device 8 issues a warning by the operation of the comparator circuit 6. will be displayed. (For example, blinking LED, buzzer, etc.) The operation of the method for detecting clogging of the rotary head during the continuous shooting period of the magnetic recording/reproducing apparatus configured as described above will be explained below. 6 and 7 are diagrams showing the input/output waveforms of each block shown in FIG. 6, the mode switching timing of the magnetic recording/reproducing device during continuous shooting, and the movement state of the tape. The comparator circuit operation period in Fig. 6 (6
This is an enlarged view of the vicinity of the figure.

First, during recording (before time t1 in FIG. 6), recording/
By the operation of the reproduction switching circuits 2a, 2b, recording signals are supplied from the recording circuit 3 to the rotary heads 1a, 1b, and they are separated from the reproduction circuit 4. Furthermore, each circuit connected after the reproduction circuit 4 is also not operating. That is, no warning is displayed on the recording display device 8.

Now, assume that a command for continuous shooting is obtained at time t1 as shown in Figure 6. Then, the tape is rewound from the position ■ to the already recorded position @, as shown in Figure 6, and stops. At time t21, when the pause cancellation command is received as shown in Figure 6, the above state is restored. Continue to maintain. Furthermore, at time t1, the operating states of the recording circuit 3 and reproducing circuit 4 are reversed to the recording state, as shown in Figure 6 and d. At time t2, a pause release command is obtained, and the control signal and recording The capstan drive is adjusted so that the phases of the control signals match. And time t
At time t4, even after the phases of both control signals match, the reproduction state is maintained for a certain period of time, and at time t4, the recording state is returned again. That is, as shown in Figure 6 and d, the operations of the recording circuit 3 and the reproducing circuit 4 are reversed, and the tape is recorded again from the position .

(At the time of splicing, the amount of tape rewinding is set so that the overlapping recording portion occurs from position ■ to position ■ as shown in Figure 6.) From the above explanation, from time t1 to time t3 During this period, the rewinding and stopping of the tape as well as the capstan drive adjustment during playback are unstable, so even though the playback circuit 4 is in operation, it is not stable in synchronization with the head switching signal. (Indicates that the envelope is flat.) No playback output can be obtained. However, at time t3, a stable reproduction output is obtained by the above-described operation, and the input/output waveforms of each circuit at that time are shown in FIG.

In FIG. 7, b indicates the operating period of the comparator circuit, and b indicates the head switching signal. At time t3, the phases of the playback and recording control signals match as described above, so a stable playback output can be obtained. However, at time t4, the recording state is resumed. That is, the output of the envelope detection circuit 6 becomes a stable detection voltage as shown in FIG. 7C if there is no recording error before continuous shooting and no clogging of the rotary head during continuous shooting. Then, the comparison circuit 6 (
The reference voltage is set to 1 as shown in FIG. 7C. ), the detected voltage is higher than the reference voltage ■1, so the output of the comparator circuit is in a High state during the period from time t3 to t4, as shown in FIG. 7d.

(It is also possible to configure it so that all outputs are Low.) However, at the switching position of the playback output (such as time 16.16.17 in Fig. 7), there is a high possibility that the playback output will include switching noise. Therefore, Figure 7d
As shown in FIG. 2, there may be a case where the output of the comparator circuit 6 becomes Low at the above position.

Furthermore, if a recording error occurs or the rotating head 1i) occurs during the pause period, no playback output can be obtained from the rotating head, so the output of the envelope detection circuit 5 is Between t6 and t7, the reference voltage ■
It will be lower than 1. That is, the output of the comparator circuit 6 becomes Low during the period as shown in FIG. When a low level is detected and a warning is displayed, the person operating the magnetic recording/reproducing device can know that there has been a recording error or that the rotating head is clogged. (For example, TV Technology, August 1983 issue, Plea-45) In the above description, the number of rotating heads is two, but the same holds true even if there are three or more rotating heads. Furthermore, while the reproduction signal detection period is set after the release of the pause during continuous shooting, it is clear that the same holds true even if the period is set to a period during which the tape is rewound by a certain amount.

Problems to be Solved by the Invention However, with the above configuration, the phases of the playback/recording control signals match after the tape pause is released during splicing, and a stable playback output is obtained. Even though there is no error or blinding of the rotating head, the output of the comparator circuit is not constant due to the effect of switching noise occurring at the switching position of the reproduction output, and a spike-like noise is generated at the position, Wrong information will be transmitted to the display device, which may cause malfunction. The present invention aims to solve the above problems.

Means for Solving the Problems The present invention aims to solve the above problems by: 1. During continuous shooting, set the detection period to the period from when the tape pause is released and the phases of the playback/recording control signals match until the recording state returns again, excluding the head switching position. The detection period setting circuit is provided between a comparison circuit that operates according to the detected voltage of the reproduced output and a display device that displays a warning according to the output of the two comparison circuits.

Operation According to the present invention, with the above-described configuration, it is possible to detect a reproduced output having correct information that is not affected by switching noise occurring at the switching position of the reproduced signal during the operation period of the comparator circuit.

Embodiment FIG. 1 is a block diagram showing a method for detecting clogging of a rotary head during continuous shooting of a magnetic recording/reproducing apparatus according to the present invention.

In FIG. 1, except for the detection period setting circuit 7 connected between the comparator circuit 6 and the display device 8, the rest is the same as the conventional example shown in FIG. 6, so the explanation will be omitted here. In addition, 7
is a detection period setting circuit which receives the head switching signal as an input and limits the period during which the output of the comparison circuit 6 is transmitted to the display device 8.

The operation of the rotary head clogging detection method of the present invention will be described below with reference to the drawings. FIG. 2 is a timing chart showing the input and output waveforms of each block shown in FIG. 1, and particularly shows the vicinity of the operating period of the comparator circuit in an enlarged manner.

The operation during recording is the same as in the conventional example, and the mode switching timing of the magnetic recording/reproducing device and the moving state of the tape during continuous shooting are the same as in the conventional example shown in FIG.

Therefore, only the operation period of the comparator circuit, which operates differently from the conventional example, will be explained below.

In FIG. 2, the phases of the reproduction/recording control signals match at time t3, and after maintaining the reproduction state for a certain period of time, the recording state returns again at time t4.
In Figure a), the comparator circuit 6 operates. Note that FIG. 2 shows a head switching signal.

If there is no recording error or clogging of the rotating head, after time t3, a stable playback output synchronized with the head switching signal from the playback circuit 4 can be obtained. The output is a nearly constant DC voltage.

At this time, if the reference voltage of the comparator circuit 6 is vl, the output of the comparator circuit remains h stably during the period excluding the switching position of the reproduction signal. (It is at a constant level of either Htgh or Low.) So.

From among the outputs of the comparator circuit 6, only the information at the time shown in FIG. Comparison circuit 6 at times tA, tB, tq
All outputs are Htgh level (or Low level)
The display device 8 indicates that the comparator circuit 6 is in operation during the operation period.
Since the outputs of the comparison circuit are all at the I (iqh level), no warning is displayed.Furthermore, the head switching position where the operation of the comparison circuit 6 is not stable is excluded from the recording error/rotating head clogging detection period. .

Furthermore, if a recording error occurs or the rotary head becomes clogged during the pause period, no playback output can be obtained from the rotary head 1a or 1b. A period occurs where the voltage is lower than v1. At this time, the detection positions of the detection period setting circuit 7 are the same positions tA, tB, tq as described above.
If it was.

At time tB, a low level signal is transmitted to the display device 8, and even though the comparator circuit 6 is in operation, the output of the comparator circuit 6 is at a low level, so the display device 8 displays a warning. However, it is possible to detect the occurrence of a recording error or a rotary head scratch (t#).

A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows a rotary head jam during continuous shooting of a magnetic recording/reproducing apparatus showing a second embodiment of the present invention.

This is a block diagram showing a detection method. Only a comparison circuit, a detection period setting circuit, and a display device are shown, and the other blocks are omitted because they are the same as in the previous embodiment. In FIG. 3, the detection period setting circuit 7 includes a monostable multivibrator 9&~9d (input A
The rising edge is detected, and the input B detects the falling edge. ), logic circuits 10a to 10d receiving the pulse signal and a signal indicating the comparison circuit operation period, and a switching element 11
It is composed of.

The operation of the second embodiment configured as above will be explained below. Note that FIG. 4 is a timing chart showing input and output waveforms of each block in FIG. 3.

In this embodiment, the operation during recording, the mode switching of the magnetic recording/reproducing device during continuous shooting, and the moving state of the tape are the same as those in the conventional example, and will therefore be omitted.

In Fig. 4, a indicates the operating period of the comparator circuit, and b indicates the head switching signal. During the period from time t3 to t4, the phases of the playback/recording control signals are consistent, and stable playback output is obtained. It is being At this time, monostable multivibrators 9a to 9d that receive the head switching signal as input
and logical mouth, path 10. As a result of the operation a, after a time Δt2 from the head switching position, the width Δt3 is changed as shown in FIG.
A pulse signal with . Furthermore, performing a logical product between the pulse signal and a signal indicating a comparator circuit operation period,
The switching element 11 connected to the output of the comparator circuit 6 is opened and closed.

If there is no recording error or rotary head blockage, the output of the comparator circuit 6 changes from time t3 to time t as shown in FIG. 4d.
The period up to 4 is stable except for the head switching position. The output of the comparison circuit 6 is transmitted only during the period when the switching element 11 is closed, that is, the period shown in FIG.
The output shown in FIG. 4e is sent to the display device 8 by the logic circuits 0c and IQd. At this time, as shown in Figure 4e,
The output of the detection period setting circuit 7 is at a low level (or high
However, if a recording error or a clogging of the rotary head occurs, the output of the comparator circuit 6 is As shown in FIG. At this time, due to the operation of the logic circuits 10c and 10d, the output of the two detection period setting circuit 7 is at the Htgh level only during this period, as shown in FIG. The person operating the device can see the blindness of the rotating head.

In the above description, the number of rotary heads is two, but the same holds true even if there are three or more rotary heads. Furthermore, the detection period of the playback signal during continuous shooting is set after the pause is released.

It is clear that the same thing holds true even when the period is set to rewind the tape by a certain amount.0 Effects of the Invention As described above, the present invention rewinds the tape by a certain amount during recording to perform continuous shooting. In a magnetic recording/reproducing device, the period from when the temporary stop of the tenip is released and the phases of the reproduction/recording control signals match until the recording state is returned again, that is, the period other than the reproduction signal switching position of the comparator circuit operating period. By providing a detection period setting circuit that transmits the output of the comparison circuit to the display device, it is not affected by switching noise that occurs when switching playback signals, that is, it does not cause malfunctions, and it is possible to prevent recording errors and rotational head rotation during continuous shooting. It becomes possible to detect clogging.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a device using the rotary head clogging detection method according to the present invention, FIG. 2 is a timing chart showing input and output waveforms of each block in FIG. 1, and FIG. FIG. 4 is a block diagram of a device using the rotating head clogging detection method in the embodiment, FIG. 4 is an input/output waveform diagram of each block in FIG. 3, and FIG. FIG. 6 is a timing chart showing mode switching and tape running states of the magnetic recording/reproducing device during continuous shooting, and FIG. 7 is an input/output waveform diagram of each block shown in FIG. 6. 6...-envelope detection circuit, 6...
Comparison circuit. 7...Detection period setting circuit. Figure 6 Figure 7

Claims (2)

[Claims] (1) During splicing, the tape is rewound a certain amount and then stopped, and after the pause is released, the playback state is maintained for a certain period of time, and when the playback control signal and the recording signal control signal match in phase, recording starts again. A magnetic recording/reproducing device comprising: a reproducing circuit connected to a rotary head that operates during a period other than the recording, an envelope detection circuit connected to the reproducing circuit, and a comparison circuit operating according to a detection voltage of the envelope detection circuit. , furthermore, a head switching signal is input, and the comparator circuit outputs an output during a period other than the switching portion of the switching signal during a period from when the phases of the reproduction control signal and the recording signal control signal match to when the recording state is returned again. and a detection period setting circuit for transmitting the information to a display device. (2) The detection period setting circuit outputs a pulse signal having a constant pulse width that does not extend to the next switching position after a certain period of time from the switching position of the head switching signal, and during the period in which the pulse signal is detected, the comparison circuit 2. A method for detecting clogging in a rotary head of a magnetic recording/reproducing apparatus according to claim 1, wherein the output is transmitted to a display device.