JPH03157806A - Magnetic head clogging detector for magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To shorten the time required for restart of the recording operation by detecting the clogging of a magnetic head at the time of rewinding of a magnetic tape for consecutive recording processing after the stop of the recording operation. CONSTITUTION:A drop-out detecting means 11 detects a signal drop-out part in the reproduced video signal obtained from a reproducing system circuit, and a clogging detecting means 12 detects the occurrence states of signal drop- out parts corresponding to magnetic heads 4a and 4b based on an output signal indicating the switching timing of a head switching means 5 and the detection signal of the drop-out detecting means 11 to discriminate whether magnetic heads 4a and 4b are clogged or not. That is, clogging of magnetic heads is detected in the period of magnetic tape rewinding for consecutive recording processing after the stop of the recording operation. Thus, the recording operation is quickly restarted.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a stationary video tape recorder (hereinafter referred to as V
The present invention relates to a magnetic head clogging detection device used in magnetic recording and reproducing devices such as TR (hereinafter referred to as "TR") and camera-integrated VTRs.

[Conventional technology]

For example, in a helical scan type magnetic recording/reproducing device,
A running magnetic tape is wound diagonally around a rotating drum, and a plurality of magnetic heads provided on the rotating drum record on the magnetic tape. In such a magnetic recording/reproducing apparatus, if any of the rotary heads becomes clogged during a recording operation, a situation occurs in which recording is not performed on the video track scanned by the clogged magnetic head. Therefore, in order to cope with such a situation, the conventional magnetic recording/reproducing apparatus is equipped with a magnetic head clogging detection device.

In this type of conventional magnetic head clogging detection device, the sixth
As shown in the figure, in the operation mode U, the clogging detection operation is performed in the clogging detection period u3 provided within the continuous recording processing period V. The continuous recording processing period V is
These are set to enable phase alignment when recording is restarted, and include the tape running stable period uZ, the above-mentioned clogging detection period u3, and the recording amplifier rise period u3.
Consisting of Further, the continuous recording processing period (2) is started when an operation for restarting the recording operation is performed while the VTR is in the recording-time stop mode U in which the recording operation is temporarily stopped.

That is, in the recording-time stop mode u1, when an operation to restart the recording operation is performed, the reproduction operation is instructed by the recording/reproduction mode switching signal q output from the system control (not shown), and the connection is performed based on this signal q. A recording processing period V is started. In addition, the magnetic head
It is connected to the reproducing circuit from the recording-time stop mode u1 according to instructions from the tape recording control signal outputted from the system control. Next, when the tape running stable period u2 has elapsed, the clogging detection gate signal S output from the system control becomes High.
Based on this signal S, a clogging detection operation is started.

Next, when the clogging detection period u3 elapses, a recording operation is instructed by the recording/reproduction mode switching signal q, the clogging detection gate signal S becomes Low, and the recording amplifier rise period u4 begins. When this recording amplifier rise period u4 has elapsed, the splicing recording processing period V ends, and the magnetic head is connected to the recording system path according to the instruction of the tape recording control signal t, and the recording operation is restarted. Note that the tape running direction r is the positive direction in each of the above-mentioned operation modes.

[Problem to be solved by the invention]

However, in the conventional magnetic head clogging detection device described above, the clogging detection period U in the playback mode is provided within the continuous recording processing period V from the recording-time stop mode to the recording mode. Furthermore, it is necessary to set the playback mode during the clogging detection period U and switch to the recording mode when the clogging detection period U3 ends, resulting in a long time until the recording operation is restarted. In addition, since the clogging detection operation is performed during continuous recording when the operator attempts to restart the recording operation after once stopping the recording state, it is possible to detect clogging of the magnetic head at this time. If detected, there is a problem that valuable recording opportunities may be missed.

[Means to solve the problem]

In order to solve the above problems, a magnetic head clogging detection device for a magnetic recording/reproducing device according to the present invention provides a recording system circuit that performs predetermined processing on a video signal when recording the video signal on a magnetic tape, such as a recording amplifier. A playback circuit that performs predetermined processing on the video signal when playing back the video signal from the magnetic tape, such as a playback amplifier, head switching means that sequentially switches and operates a plurality of magnetic heads, and a recording system that connects the magnetic heads. Recording/switching between circuit and playback circuit
In a magnetic head clogging detection device for a magnetic recording and reproducing device, the magnetic head clogging detection device is provided with a reproduction switching means, and rewinds a magnetic tape for splicing processing when recording operation is stopped.
The following measures have been taken:

That is, a display means for displaying the clogging state of the magnetic head, a dropout detection means for detecting a signal dropout part in a reproduced video signal, an output signal indicating the switching timing of the head switching means, and a dropout detection means for detecting the switching timing of the head switching means. Based on the detection signal, the state of occurrence of signal dropouts corresponding to each magnetic head, for example, whether the number of consecutively occurring signal dropouts is less than a reference value, is detected, and the presence or absence of clogging of the magnetic head is detected. clogging detection means for determining the clogging.

Also, during the clogging detection period when rewinding the magnetic tape for the splice recording process, the recording/playback switching means is controlled so that the magnetic head is connected to the playback system circuit, and the playback system circuit controls the playback circuit and the recording circuit so that the circuit operates and the recording circuit stops operating;
A control means is provided for causing the display means to display the clogging state when the clogging state of the magnetic head is detected by the clogging detection means.

[For production]

According to the above configuration, when the recording mode is stopped and rewinding of the magnetic tape is started for splicing processing,
The control means controls the recording/reproduction switching means so that the magnetic head is connected to the reproduction system circuit, and also controls the reproduction system circuit to operate. Thereby, the reproduced video signal obtained by the magnetic head that sequentially scans the magnetic tape running in the opposite direction is processed by the reproduction system circuit.

At this time, the dropout detection means detects a signal dropout part in the reproduced video signal obtained from the reproduction system circuit,
The clogging detection means detects the occurrence state of a signal dropout corresponding to each magnetic head based on the output signal indicating the switching timing of the head switching means and the detection signal of the dropout detection means, and detects the occurrence of a clogging of the magnetic head. Determine the presence or absence.

Therefore, when the clogging state of the magnetic head is detected by the clogging detection means, the control means causes the display means to display the clogging state. This allows the user of the magnetic recording/reproducing apparatus to know whether the magnetic head is clogged.

As mentioned above, this device detects clogging of the magnetic head during the rewinding period of the magnetic tape for continuous recording processing after the recording operation has stopped, so that the recording operation can be resumed quickly. be able to. Furthermore, if the magnetic head is clogged, this can be detected as early as when the recording operation is stopped.

(Example) An example of the present invention will be described below based on FIGS. 1 to 5.

As shown in FIG. 1, the magnetic head clogging detection device for a magnetic recording/reproducing apparatus according to the present invention has a recording/reproducing switching circuit 2 as recording/reproducing switching means. This recording/reproduction changeover switch circuit 2 is connected to a second
Based on the tape recording control signal e shown in the figure, the R head 4
a and the L head 4b are switched to a recording system or a reproduction system. Recording/playback switch circuit 2
In this embodiment, two magnetic heads, an R head 4a and an L head 4b, which record video signals on the magnetic tape 3 and detect video signals from the magnetic tape 3 are connected to the magnetic tape 3. . Further, a head changeover switch circuit 5 as a head changeover means is connected to the recording/reproduction changeover switch circuit 2. The head changeover switch circuit 5 is configured to appropriately switch between the R head 4a and the L head 4b at an appropriate timing during recording or reproduction. As a result, during recording, recording is performed alternately on the video track of the magnetic tape 3 by the R head 4a and the L head 4b, while during playback, the recording is performed alternately on the video track of the magnetic tape 3.
The R head 4a and the L head 4b alternately reproduce the video track from the video track. The head changeover switch circuit 5 also receives a head changeover signal C indicating the timing of switching between the R head 4a and the L head 4b.
is supplied from a servo circuit 15 together with a clogging detection circuit 12 as clogging detection means. The servo circuit 15 controls the rotational speed of a rotary head drum (not shown) based on the head switching signal C.

Further, the head changeover switch circuit 5 includes a recording amplifier 6 as a recording system circuit that amplifies the video signal supplied from the modulation circuit 8 and supplies it to the head changeover switch circuit 5; A dropout detection circuit 11 that amplifies the video signal and supplies it to the demodulation circuit 10 is connected to the playback amplifier 7 that serves as a playback circuit that amplifies the video signal and supplies it to the demodulation circuit 10. The operations of the recording amplifier 6 and the reproduction amplifier 7 are controlled by a recording/reproduction mode switching signal a supplied from the system control circuit 1. A modulation circuit 8 that modulates a video signal supplied from a video signal processing circuit 9 into an FM signal is connected to the recording amplifier 6. A demodulation circuit 10 is connected to the reproduction amplifier 7 , which demodulates a reproduction FM signal g, which is a video signal supplied from the reproduction amplifier 7 , and supplies the demodulated signal to the video signal processing circuit 9 .

The video signal processing circuit 9 is configured to perform processing suitable for recording and reproduction, respectively, on the recorded video signal and the reproduced video signal.

The above-mentioned dropout detection circuit 11 detects a dropout detection signal that is Low when a video signal is present and High when a video signal is not present in the reproduced FM signal g obtained from the reproduction amplifier 7. The signal is output to the detection circuit 12. The operation of the clogging detection circuit 12 is controlled by the clogging detection gate signal d supplied from the system control circuit 1.
a head switching signal C supplied from the servo circuit 15;
A clogging detection operation is performed based on a dropout detection signal supplied from the dropout detection circuit 11. That is, during the period of the dropout detection signal corresponding to each operation timing of the R head 4a and L head 4b obtained by the head switching signal C, the state of being High occurs continuously throughout the period, and the If the counted value exceeds the reference value, it is determined that there is a clogging, while if the counted value is 1 2 below the reference value, it is determined that there is no clogging, and the system controls the clogging determination signal i that indicates this determination result. It is configured to output to circuit 1. The above reference value is set to several times (3 to 5 times) in order to prevent false detection.

The system control circuit 1 sends a tape recording control signal e, which instructs the R head 4a and the L head 4b to switch to the recording system or the reproducing system, for recording/reproduction switching according to the operation mode selected by the operation keys of the VTR, etc. A recording/playback mode switching signal a is output to the switch circuit 2 to instruct the recording amplifier 6 and the playback amplifier 7 to operate and stop, and the clogging detection circuit 12 is activated. Or the clogging detection gate signal d instructing to stop the operation is sent to the clogging detection circuit 12.
It is designed to output to. Further, when the system control circuit 1 receives a clogging determination signal i from the clogging detection circuit 12 indicating that there is a clogging, the system control circuit 1 causes the display section 13 serving as a display means to display that there is a clogging. It has become. Furthermore, the system control circuit 1 controls the tape drive section 14 that runs the magnetic tape 3 according to the operation mode f.

In the above configuration, as shown in FIG. 2, when the operation mode f of the VTR is the recording mode f1, the system control circuit 1 sends a recording/recording mode instruction to the recording amplifier 6 and the reproduction amplifier 7 to instruct the recording mode. The playback mode switching signal a is supplied to the recording/playback switch circuit 2.
A tape recording control signal e is supplied that instructs the connection of the head 4a and the L head 4b to the recording system. This results in
The recording amplifier 6 operates, the reproduction amplifier 7 stops operating,
In the recording/reproducing switch circuit 2, the R head 4a and the L head 4b are connected to a recording system. At this time, the system control circuit 1 also controls the tape drive section 14.
is controlled, the tape running direction a becomes the positive direction, and the clogging detection gate signal d supplied from the system control circuit 1 to the clogging detection circuit 12 becomes Low.
becomes. As a result, the clogging detection circuit 12 stops operating. Furthermore, the head changeover switch circuit 5 performs a switching operation to alternately switch between the R head 4a and the L head 4b, and the servo circuit 15 controls the rotational speed of the rotary head drum.

Further, the video signal that has been subjected to predetermined processing suitable for recording by the video signal processing circuit 9 is modulated into an FM signal by the modulation circuit 8 and input to the recording amplifier 6. recording amplifier 6
The amplified FM recording signal is alternately supplied to the R head 4a and the L head 4b via the head changeover switch circuit 5 and the recording/reproduction changeover switch circuit 2.

As shown in FIG. 3, the R head 4a and the L head 4b alternately scan each video track of the magnetic tape 3, and a video signal is recorded on the magnetic tape 3.

Next, when a recording stop key (not shown) of the VTR is operated, the operation mode f becomes a rewinding mode f2 when recording is stopped, in which the magnetic tape 3 is slightly rewound. This rewind mode f2 when recording is stopped is for continuous recording processing that allows phase alignment to be performed when recording is restarted.

At this time, the system control circuit 1 supplies the recording/playback mode switching signal a instructing the playback mode to the recording amplifier 6 and the playback amplifier 7, and the recording/playback switch circuit 2 is supplied with the R head 4a and the L head 4a. head 4b
A tape recording control signal C is supplied which instructs the connection between the recording medium and the reproduction system. As a result, the recording amplifier 6 stops operating,
When the playback amplifier 7 starts operating, the recording/playback switch circuit 2 switches the R head 4a and the L head 4b.
and the reproduction system are connected. At this time, the tape drive section 14 is controlled by the system control circuit 1, so that the tape running direction is reversed, and a clogging detection gate signal is supplied from the system control circuit 1 to the clogging detection circuit 12. d becomes High. Thereby, the clogging detection circuit 12 starts clogging detection.

A video signal recorded on the magnetic tape 3 is detected by a 5 6 R head 4a and an L head 4b which alternately operate the video tracks of the magnetic tape 3. At this time, the operating trajectories of the R head 4a and the L head 4b on the magnetic tape 3 become as shown by the dashed line in FIG. This scanning trajectory always passes through a recording pattern having the same azimuth as the reproducing head.

The video signal detected as described above is input to the playback amplifier 7 via the recording/playback switch circuit 2 and the head switch circuit 5. The video signal amplified by the reproduction amplifier 7, that is, the reproduction FM signal g, is input to a dropout detection circuit 11 and a demodulation circuit 10. The demodulation circuit 10 demodulates the reproduced FM signal g and outputs it to the video signal processing circuit 9, and the video signal processing circuit 9 subjects the input video signal to predetermined processing suitable for reproduction.

Further, the dropout detection circuit 11 outputs a dropout detection signal to the clogging detection circuit 12.

Here, if neither the R head 4a nor the L head 4b is clogged, as shown in FIG.
The reproduced FM signal g includes a reproduced signal corresponding to the operation timing of the R head 4a and the L head 4b indicated by the head switching signal C. Therefore, the dropout detection signal output from the dropout detection circuit 11 is as follows:
Part of the period corresponding to the operating timing of the R head 4a and the L head 4b becomes Low. This allows the R head 4a or the L head 4 to receive a dropout detection signal.
During the period corresponding to the actuation timing b, the number of times the signal is set to High becomes less than or equal to the reference value. Therefore, the clogging detection circuit 12 outputs a clogging determination signal i indicating that there is no clogging to the system control circuit 1.

On the other hand, if the L head 4b is clogged, for example, the reproduction signal corresponding to the operation timing of the L head 4b no longer appears in the reproduction FM signal g, as shown in FIG. Therefore, the dropout detection signal remains High during the period corresponding to the operating timing of the L head 4b. As a result, the dropout detection signal remains High continuously during the period corresponding to the operation timing of the L head 4b8.
The number of times that exceeds the standard value. Therefore, the clogging detection circuit 12 outputs a clogging determination signal i indicating that there is a clogging to the system control circuit 1. The system control circuit 1, which receives this clogging determination signal i, causes the display unit 13 to display that there is a clogging. This allows the operator to know that clogging has occurred.

As described above, the system control circuit 1 sets the clogging detection gate signal d to Low after allowing sufficient time for clogging detection within the period of the rewind mode f2 when recording is stopped. As a result, the clogging detection circuit 12 stops operating, and the clogging detection operation ends.

Thereafter, the system control circuit 1 again supplies the recording/playback mode switching signal a that instructs the recording mode to the recording amplifier 6 and the playback amplifier 7, and the recording/playback switch circuit 2 is supplied with the R head 4a and A tape recording control signal e that instructs the connection between the L head 4b and the recording system.
is supplied. As a result, the recording amplifier 6 is activated, the reproducing amplifier 7 is deactivated, and the recording/reproducing switch circuit 2 performs switching so that the R head 4a and the L head 4b are connected to the recording system. Further, the magnetic tape 3 is stopped by controlling the tape drive section 14 by the system control circuit 1. The VTR thus stands by with the video signal processing system held in the recording mode.

〔Effect of the invention〕

As described above, the magnetic head clogging detection device for a magnetic recording and reproducing apparatus according to the present invention includes a display means for displaying a clogging state of a magnetic head, and a dropout detection device for detecting a signal missing portion in a reproduced video signal. Based on the head switching means, an output signal indicating the switching timing of the head switching means, and a detection signal of the dropout detection means, the occurrence state of a signal dropout corresponding to each magnetic head is detected, and the presence or absence of clogging of the magnetic head is determined. clogging detection means for detecting a blockage, and controlling a recording/playback switching means so that the magnetic head is connected to a playback system circuit during a blockage detection period during rewinding of the magnetic tape for splicing recording processing. , and controls the reproducing circuit and the recording circuit so that the reproducing circuit operates and the recording circuit stops operating, and when a clogging state of the magnetic head is detected by the clogging detection means, an indication is displayed. This configuration includes a control means for causing the means to display the clogging state.

Therefore, detection of clogging in the magnetic head can be performed when rewinding the magnetic tape for continuous recording processing after the recording operation is stopped, and the time required to restart the recording operation can be shortened. Further, if the magnetic head is clogged, this can be displayed when the recording operation is stopped, so that the user can be notified quickly.

[Brief explanation of the drawing]

1 to 5 show one embodiment of the present invention. FIG. 1 is a block diagram showing the overall configuration of a magnetic head clogging detection device. FIG. 2 is a timing chart showing the recording/reproducing mode switching signal, tape running direction, head switching signal, clogging detection gate signal, tape recording control signal, and operation mode. FIG. 3 is an explanatory diagram showing the recording operation on the magnetic tape when the magnetic tape is running in the forward direction and the reproducing operation from the magnetic tape when the magnetic tape is being rewound. Figure 4 shows the state when the magnetic head is not clogged.
Head switching signal, clogging detection gate signal, playback FM
5 is a timing chart showing a signal and a dropout detection signal. FIG. 5 is a timing chart showing a head switching signal, a clogging detection gate signal, a reproduction FM signal, and a dropout detection signal when the L head is clogged. FIG. 6 shows a conventional example, and is a timing chart showing a recording/reproducing mode switching signal, tape running direction, clogging 1 2 detection gate signal, tape recording control signal, and operation mode. ■ is a system control circuit (control means), 2 is a recording/playback switching circuit (recording/playback switching means),
3 is a magnetic tape, 4a is an R head, 4b is an L head, 5
is a head changeover switch circuit (head changeover means), 6
1 is a recording amplifier (recording circuit), 7 is a reproduction amplifier (reproduction circuit), 11 is a dropout detection circuit (dropout detection means), 12 is a clogging detection circuit (clogging detection means), and 13 is a display unit ( display means).

Claims (1)

[Scope of Claims] 1. A recording system circuit that performs predetermined processing on a video signal when recording the video signal on a magnetic tape, and a reproduction system circuit that performs predetermined processing on the video signal when reproducing the video signal from the magnetic tape. and a head switching means for sequentially switching and operating a plurality of magnetic heads, and a recording/reproduction switching means for switching the connection of the magnetic heads between a recording system circuit and a reproduction system circuit. In a magnetic head clogging detection device of a magnetic recording and reproducing device in which a magnetic tape is rewound for processing, a display means for displaying a clogging state of a magnetic head, and a signal missing part in a reproduced video signal is detected. Based on the dropout detection means, the output signal indicating the switching timing of the head switching means, and the detection signal of the dropout detection means, the occurrence state of the signal dropout corresponding to each magnetic head is detected, and the occurrence state of the signal dropout portion corresponding to each magnetic head is detected, and the clogging of the magnetic head is detected. A clogging detection means for determining the presence or absence of a clogging; and a recording/reproduction switching means for connecting the magnetic head to a reproduction system circuit during a clogging detection period during rewinding of the magnetic tape for the above-mentioned splicing recording process. control,
The reproduction system circuit and the recording system circuit are controlled so that the reproduction system circuit operates and the recording system circuit stops operating, and when the clogging state of the magnetic head is detected by the clogging detection means, the display means 1. A magnetic head clogging detection device for a magnetic recording/reproducing device, comprising: a control means for displaying a clogging state in a magnetic recording/reproducing device.