JPS6011867B2 - Long-term magnetic recording and reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording/reproducing apparatus configured to be capable of long-time recording.

Conventionally, long-term magnetic recording/reproducing devices (hereinafter referred to as long-term VTRs) are mainly used for monitoring and observation, and are often left unattended for several hours or even days during recording.

Under such conditions of use, if the head becomes clogged, recording for several hours or even days becomes invalid. Therefore, the present invention is designed to prevent the head from becoming magnetic when the head is clogged or due to other causes during recording. To provide a long-term magnetic recording and reproducing device that can quickly detect and notify when a regular recording operation is not being performed on a tape.

An explanation will be given below based on one embodiment of the present invention.

FIG. 1 shows a block diagram of a long-duration VTR according to an embodiment of the present invention, in which 1 and 2 are rotating video heads, and 3 and 4 are rotating phase detection heads, which are in contrast to the rotating video heads 1 and 2. There are two of them. Reference numeral 5 denotes a switching pulse circuit which inputs the output signals of the rotary phase detection heads 3 and 4 and outputs a square wave signal having a constant relative positional relationship with the input video signal.

Reference numeral 6 denotes a frequency dividing circuit which divides the frequency of the output signal of the switching pulse circuit 5 into 1'N and outputs the frequency divided signal.

Reference numeral 7 denotes a monostable multipipulator which inputs the output signal of the frequency dividing circuit 6 and outputs a gate pulse signal.

Reference numerals 8 and 9 denote gate circuits for selectively instructing the rotating video heads 1 and 2 to record or reproduce.・This command selectively commands the head 1 to record or reproduce.

The gate circuit 8 consists of a switch 10, and the gate circuit 9 consists of a switch 11. Reference numeral 12 denotes a recording video signal processing circuit which inputs an input video signal, frequency modulates the signal, and outputs the signal.

13 and 14 are recording amplifiers, both of which input the output signal of the recording video signal processing circuit 12, and the output signals are connected to the rotating video heads 1 and 2 via contacts a and c of switches 10 and 11, respectively. .

15 and 16 are regenerative amplifiers, which are connected to switches 10 and 1, respectively.
The playback signals of the rotary video heads 1 and 2 are inputted through contacts b and d of 1, amplified, and output.

17 is a reproduction signal processing circuit, which connects contacts e and f of the switch 20;
The output signal from the recording video signal processing circuit 12 or the output signal from the reproduction signal processing circuits 15 and 16 is selectively inputted through the input signal processing circuit 1, and the input signal is demodulated and output.

18 is an integrating circuit which inputs the output signal of one of the regenerative amplifiers 16 and outputs its integrated value. Reference numeral 19 denotes a notification circuit which receives the output signal of the integrating circuit 18 and operates to issue a warning when the output signal of the regenerative amplifier 16 decreases and the output signal of the integrating circuit 18 decreases.

The operation of the long-time VTR shown in the block diagram will be described when recording is performed in the 4-hour mode (recording once every 4 fields). In the 4-hour mode, the tape running speed is 1
/4.

When this recording time mode is an even number of hours, the rotating video head that records on the magnetic tape is specialized.
The head that performs recording is designated as rotary video head 1. By passing the rotation detection signals of the rotating video heads 1 and 2 detected by the rotating phase detection heads 3 and 4 through the switching pulse circuit 5, the phase of the square wave signal as shown in Fig. 2A is normally added to the VTR. A servo circuit (not shown) maintains a constant relative phase relationship with the input video signal. The square wave signal output from the switching pulse circuit 5 is divided into 1/2 by the frequency dividing circuit 6.
4 and outputs a signal as shown in FIG. 2C. Furthermore, the output signal of the frequency divider circuit 6 is inputted to the monostable multipipulator 7, and a gate pulse as shown in FIG. 2 is outputted. Gate circuit 8 that uses this gate pulse as a control signal
During the period when the gate pulse is at the logic level "L", the switch 10 is connected to the b side, and during the period when the gate pulse is at the logic level "H", the switch 10 is connected to the a side. Therefore, the switch 10 is connected to the a side once every four fields, and the input video signal is supplied by the rotating video head 1 via the recording video signal processing circuit 12 and the recording amplifier 13 and recorded on the magnetic tape. . Since the switch 11 of the gate circuit 9 of the other rotating video head 2 is connected to the d side, the video head 2 does not record, even though the rotating video head 2 system is in the recording mode. It is always in playback mode. FIG. 3 shows the above relationship expressed on a tape pattern.

In this Figure 3, ■■■■■′■′・・・・・・・・・
. . . indicates the position of the scanning track of the rotating video heads 1 and 2, and (AREc) (BR8c) indicates the period during which the switch 10 of the gate circuit 8 is connected to the contact a side, that is, the monostable multipipulator. 7 output gate pulse [
2] shows the recording pattern of the input video signal input to the rotary video head 1 during periods A and B of logic level "H". As mentioned above, the tape running speed is 1/4 of the normal speed, so when the first field is recorded (ARE.) in FIG. , and just recorded it (
AREc) is scanned by the other rotating head 2 on the track ■
Trace the recording pattern (
AREc) is played. Thereafter, for the scanning track (2), the same operation as for the scanning track (2) is repeated.
In the long-term recording mode, the switch 11 of the gate circuit 9 is always connected to the contact d side, and the rotary video head 2 system is in a reproducing state. Therefore, in the section of the scanning track ■■, the signal detected from the magnetic tape is supplied to the integrating circuit 18 via the reproducing amplifier 16. When there is no signal from the rotating video head 2, the output signal of the integrating circuit 18 disappears, and the connected notification circuit 19 operates with the output signal of the integrating circuit 18 as input, and if the rotating video head 1 is clogged, etc. It detects and notifies that the recording on the magnetic tape is not legal. In addition, when reproducing the recording made in the above manner, the switches 10 and 11 are connected to the contacts b and d, respectively, and the reproduction output amplified by the respective reproduction amplifiers 15 and 16 is transmitted to the switch 2.
is input to the reproduction signal processing circuit 17 via the contact f of 0,
The signal is demodulated and output.

FIG. 4 is a block diagram of the main part of FIG. 1 showing an embodiment of the control method for the gate circuit 9, and the same numbers as in FIG. 1 indicate the same circuits.

However, if the switch 11 of the gate circuit 9 is switched from the contact c side to the contact d side when the control signal is at logic level "H", and the switch 11 is connected to the contact C side in the long-time recording mode, the above-mentioned This turns off the recording amplifier 14. Further, 21 is a delay circuit, and 22 is a second monostable multipipulator. The output signal of the frequency divider circuit 6, which outputs a signal obtained by dividing the output signal of the switching pulse circuit 5 by 1'4 [Fig. Then, the output signal [FIG. 5C] is connected to the gate circuit 9 as a control signal for the gate circuit 9.

Therefore, for the rotary head 1 which is controlled by the output signal of the monostable multipipulator 7 [Fig. 5] and performs the recording operation during the logic level "H" period, the gate circuit 9 Stable multipipulator 22 output signal [
The rotating video head 2 is commanded to perform a reproducing operation only during the period when the signal (c) in FIG. 5 is at the logic level "H". Note that in the normal recording mode, which is not the long-time recording mode, the control signal of the gate circuit 9 turns off the recording amplifier 14 when the logic level is "H"; however, in this state, the recording amplifier 14 is not operated. By doing so, the recording operation is performed by the two rotating video heads 1 and 2. As explained above, according to the long-term magnetic recording and reproducing device of the present invention,
Recording is performed with a specific video head of the two rotating video heads, and the other video head system of the two rotating video heads is constantly or for a period shorter than N rotations of the rotating video head for a period of time. By providing a means to determine whether or not the input video signal is recorded in a normal state on a track of a magnetic tape that has been put into the playback state and the recording operation has been completed, it is possible to prevent clogging of the rotating video head during recording or other causes. If the rotating video head is not performing a proper recording operation on the magnetic tape, this can be quickly detected and reported, and this has great industrial value. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a block diagram of a long-term magnetic recording and reproducing system that is an embodiment of the present invention, FIG. 2 is a waveform diagram of the main parts of FIG. 1, and FIG. FIG. 4 is a block diagram showing another embodiment, and FIG. 5 is a waveform diagram of the main part of the block diagram in FIG. 4.

1, 2...Rotating video head, 5...
・Switching pulse circuit, 6... Frequency divider circuit, 7
, 22... Monostable multipipulator, 8, 9...
...Gate circuit, 18...Integrator circuit, 19...
...Notification circuit, 21...Delay circuit.

Fin' figure Figure 2 Figure 3 Traditional illustration Chicken drawing

Claims (1)

[Claims] 1 When recording, reduce the running speed of the magnetic tape to 1/(2N) of the normal speed.
) (N is an integer), and for two rotating video heads, one field is extracted every 2N field periods of the input video signal, and the above is divided once every N rotations of the rotating video head. In a magnetic recording/reproducing device configured to record with a specific video head out of two rotating video heads and to be able to record for a long time, in the above recording mode, the video head of the other rotating video head is
The head system is kept in the playback state at all times or for a time shorter than N rotations of the rotating video head, and it is determined whether the input video signal is recorded in a normal state on the magnetic tape track where the recording operation has been completed. What is claimed is: 1. A long-time magnetic recording and reproducing device characterized by being provided with a means for recording and reproducing information.