JP2574222B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus capable of recording for a long time by an intermittent recording method, and is used, for example, for monitoring.

2. Description of the Related Art In recent years, a magnetic recording / reproducing apparatus widely used for security monitoring of financial institutions and the like performs intermittent recording for long-term monitoring. However, these conventional devices do not have a function of automatically detecting clogging of a video head, and after recording for a certain period of time, arbitrarily reproduce and check with human eyes. However, generally, the following recording failure detection method has been considered.

FIG. 4 shows a device for detecting a recording failure of a magnetic recording / reproducing device which has been conventionally considered. 1 is a video recording circuit,
2 is a recording and reproducing head, 3 is a simultaneous reproducing head, 4 is a reproducing amplifier, 5 is a video signal demodulation circuit, 6 is a simultaneous reproducing amplifier, 7
Is a recording disable detection circuit.

The operation of the recording disable detection circuit of the magnetic recording / reproducing apparatus configured as described above will be described below.

First, a video signal passed through the video recording circuit 1 is recorded on a magnetic tape by the recording / reproducing head 2. The recorded portion is immediately traced by the simultaneous reproducing head 3, and the reproduced signal passes through the simultaneous reproducing amplifier 6 and is detected by the recording disable detection circuit 7. Therefore, it is determined whether or not the video signal is correctly recorded by a separately provided reproducing head.

Problems to be Solved by the Invention However, in the above configuration, a read-only head is required. Also, since the recording side signal is reproduced at the same time as the recording, there is a great possibility that the recording side signal having a very high level as compared with the reproduction signal directly enters the reproduction side circuit (crosstalk).
There are drawbacks in that the configuration is complicated and expensive, for example, a sufficient shield is required for both the head section and the circuit section.

The present invention has been made in view of the above problems, and provides a magnetic recording / reproducing apparatus in which reproduction is performed by the same head after recording, thereby eliminating the need for a read-only head and solving the problem of crosstalk.

Means for solving the problem In order to solve the above problems, the magnetic recording and reproducing apparatus of the present invention reproduces the recorded portion with the same head used for recording until the next recording timing, A magnetic recording / reproducing apparatus characterized in that recording is not detected due to clogging or the like.

Operation The present invention, with the above-described configuration, reproduces a signal using a head used for recording after recording a signal. Therefore, a read-only head is not required, and crosstalk does not occur because simultaneous reproduction is not performed. In addition, the performance is good.

EXAMPLES Hereinafter, a magnetic recording / reproducing apparatus according to an example of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 shows a tape pattern.

In FIG. 1, 1 is a video recording circuit, 2 is a recording / reproducing head, 4 is a reproduction amplifier, 5 is a video signal demodulation circuit, 7 is a recording disable detection circuit, 8 is a path through which recording current flows to the head 2, 9 is This is a path through which a reproduction signal flows from the head 2. Further, a timing generation circuit 14 for controlling the operation of the recording disable detection circuit 7 and the reproduction amplifier 4 is provided so that after the intermittent recording is performed, the head 2 can reproduce the data until the next recording.

In FIG. 2, 10 is a magnetic tape, 2 is the recording / reproducing head, and 11 is a recording pattern.

Regarding the magnetic recording / reproducing device configured as described above,
The operation will be described below with reference to FIGS. 1, 2, and 3.

First, FIG. 3 shows the timing, and 12 shows the timing waveform of the recording current, which indicates the timing at which the recording current 8 flows through the video recording circuit 1 of FIG. Numeral 13 denotes an operation timing waveform of the recording disable detecting circuit, which is connected to the reproducing amplifier 4 through the recording / reproducing head 2 shown in FIG.
Indicates the timing for determining whether or not a signal has been recorded by the recording disable detection circuit 7 through. In FIG. 3, the tape moves at the timing of C.

When a signal is recorded at the timing shown in FIG. 3A, the signal is recorded on the magnetic tape like the recording pattern 11 shown in FIG. Since the tape has not moved at the timing shown in FIG. 3B, the trace is traced on the recording pattern 11 shown in FIG. Therefore, the recorded signal can be reproduced, and the recording disable detection circuit 7 determines whether or not the signal is correctly recorded. Next, the tape is moved at the timing of C in FIG. 3 so that the recording / reproducing head is brought to a position corresponding to the recording pattern 11 'in FIG. 2, that is, the step feed for one field is performed. Therefore, one cycle of the intermittent recording is completed. Thereafter, this operation is repeated to perform intermittent recording and detect recording failure.

As described above, in the present embodiment, since recording and reproduction are performed during the tape stop period between step feeds, the recording pattern and the reproduction trace completely match, and as a result, the detection of recording failure becomes accurate. In particular, in a monitoring magnetic recording / reproducing apparatus in which the present embodiment is mainly used, the same magnetic tape is often used repeatedly. In such a case, if the recording track and the reproduction trace are slightly displaced, a previous Since part of the recorded portion is reproduced, there is a possibility that even if there is a clogging, it may be erroneously detected that there is no clogging, but this embodiment does not cause such a problem.

As described above, according to the present embodiment, the timing generation circuit
14 and a non-recording detection circuit 7, and the non-recording can be detected by relatively controlling the operations of the recording circuit and the reproducing circuit.

Effect of the Invention As described above, according to the present invention, since the same head used for recording is used for reproduction, a separate head for reproduction is not required, and recording is impossible due to clogging of the head with a simple circuit configuration. Detection can be performed, and an excellent effect of preventing erroneous detection even when a recorded magnetic tape is reused can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram of a recording pattern on a magnetic tape, FIG. 3 is a waveform diagram showing operation timing of a circuit, and FIG. 4 is a block diagram of a conventional example. is there. 1 ... Video recording circuit, 2 ... Recording and reproducing head, 4 ...
Reproduction amplifier, 5: video signal demodulation circuit, 7: recording disable detection circuit, 14: timing generation circuit.

Claims (1)

(57) [Claims] 1. A magnetic recording / reproducing apparatus for performing intermittent recording by using a helical scanning type recording / reproducing head and a step feed mechanism for repeating movement and stop of a tape, wherein a signal is recorded by the head during the stop. Recording means, a reproducing means for reproducing with the same head as the head after the recording in the period, and a judging means for detecting the reproduced signal and judging whether or not the signal is recorded. Magnetic recording and reproducing device.