JPH01229403A - Magnetic recording/reproducing device - Google Patents

Abstract

PURPOSE:To easily record and reproduce the secret signals by recording the azimuth with a partial inversion at record and securing the normal reproduction at reproduction only when a password coincident with the recorded one is received. CONSTITUTION:When a password is supplied from a password input means 22 at record, the signal supplied to a phase comparator 4 is switched to the output of a PG head 3 to that of a PG head 8 and the phase control of a drum 23A is inverted by 180 deg.. Then the password signal is recorded in an idle space of a magnetic tape 24. At reproduction the tape 24 is fast forwarded or rewind when the password is supplied from a password input means 33. In this case, the password recorded on the tape 24 is read out by a password signal recording/reproducing head 9. This read password is compared with that supplied from the means 33 and the drive of the tape 24 is stopped when the coincidence is obtained between both passwords. Thus the record mode is changed to the reproduction mode. In such a way, a secret picture can be easily recorded and reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing device, and more particularly to a magnetic recording and reproducing device capable of recording and reproducing confidential signals on a recording medium. .

[Prior art]

Conventionally, video signals are generally recorded on tape-like recording media (e.g.
When recording on a magnetic tape (magnetic tape), multiple magnetic heads with different azimuths are attached to one rotating drum, and the signal of one field is assigned to one track.
Each track was recorded alternately using heads with different azimuths.

Furthermore, during reproduction, the running of the tape-shaped recording medium and the phase of the above-mentioned rotating drum were controlled by control signals recorded at the same time as recording, thereby accurately tracing and scanning the recorded tracks.

[Problems to be Solved by the Invention] However, with the conventional device as described above, even if the recorded contents of the tape are confidential, as long as the recording tape is manually manipulated, it can be reproduced using a nearby playback device. Anyone could easily obtain playback record information.

In view of these conventional problems, the present invention provides a magnetic recording system that allows only the person who performed the recording operation or a specific person who knows the password used at the time of recording to reproduce the information recorded on the recording medium. The object of the present invention is to provide a device as well as a magnetic reproducing device.

[Means for Solving the Problems] In order to achieve the above object, the magnetic recording device of the present invention records signals by sequentially using a plurality of magnetic heads with different azimuths, and includes an input for inputting a password. means for recording the password; means for recording a control signal of a frequency corresponding to the recording cycle of each head; and shifting the recording phase of the plurality of magnetic heads with respect to the control signal in response to input of the password. It is characterized by comprising means. The magnetic reproducing device of the present invention sequentially uses a plurality of magnetic heads with different azimuths to reproduce signals, and includes means for inputting a password, means for reproducing a recorded password, and a means for inputting a password. means for comparing the password recorded with the reproduced password; means for reproducing the control signal recorded at a frequency corresponding to the recording cycle of each head; The present invention is characterized by comprising means for shifting the reproduction phase of the magnetic head.

[Function] With the above configuration, the recording device of the present invention records at least a portion with the azimuth reversed in response to the input of a password at the time of recording, so that the recording device of the present invention records in such a way that it cannot be played back by a normal playback device. It can be performed. Further, the playback device of the present invention allows normal playback only when a password that matches the recorded password is entered, and if the correct password is not entered, playback becomes disordered. As described above, according to the present invention, it is possible to easily record and reproduce confidential images.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a signal flow during recording according to an embodiment of the present invention.

First, the operation during recording will be explained with reference to FIG. 1st
The video signal input from the external input terminal 1 shown in the figure is supplied to the magnetic head through the video signal processing circuit 2. At the same time, the vertical synchronization signal is separated from the video signal by the synchronization signal separation circuit 21. The frequency is divided by /2 and output. Further, the output of the PG head 3 for detecting the rotation of the drum 23A is input to the phase comparison circuit 4, where the phase is compared with a signal obtained by dividing the synchronization signal separated from the video signal into 1/2. The control circuit 5 controls the rotational phase of the drum motor 23 in accordance with the output of the phase comparison circuit 4, and rotates the drum motor 23 at a predetermined phase. The drum 23 is equipped with two heads with different azimuths that rotate with a phase difference of 180 degrees, and these heads are switched and used every time the drum rotates 180 degrees. Record the video signal from.

At the same time, a signal from the synchronization signal separation circuit 21 is output to the control signal recording circuit 6, and a control signal having a frequency equal to the drum rotation frequency output from the control signal recording circuit 6 in synchronization with the signal is sent to the amplifier 25. After that, the control head 7 records the data on the tape. In this way, the track of the video signal and the position of the control signal, including the azimuth, are determined to be one.

Next, the recording operation when a password for confidential information is input will be described with reference to the flowchart of FIG. 2.

In FIG. 1, reference numeral 8 denotes a phase inversion PG head provided at a position 180 degrees opposite to the PG head 3 used for normal recording. When a password is input using the password input means 22 such as a keyboard (step Sl)
, the signal supplied to the phase comparator circuit 4 is switched from the output of the PG rad 3 to the output of the PG head 8 described above, and the phase control of the drum 23A is reversed by 180 degrees (step S2).
.

Then, the password signal input from the password input means 22 is recorded in an empty space on the tape 24 (for example, a part of the control track) by the password signal recording/reproducing head 9 (step S3). The control signal outputted from the control signal recording circuit 6 is recorded in synchronization with a signal obtained by dividing the frequency of the synchronizing signal separated from the synchronizing signal separating circuit 21 into two parts, as in normal recording.

Therefore, the recording timing of each head when entering a password is reversed in phase by 180" with respect to the control signal. In other words, where the + (plus) azimuth head should normally record, the - (minus) azimuth head The data is recorded with a positive azimuth head at a location that should originally be recorded with a negative azimuth head (step S4).

FIG. 3 shows the signal flow during reproduction according to the embodiment of the present invention, and FIG. 4 shows the operation during reproduction.

Next, the reproduction operation of the embodiment of the present invention will be explained with reference to FIGS. 3 and 4. During playback, first a certain password is input from the password input means 33 (step 5ll), the password signal is input to the system controller 10, and accordingly the mode is changed to cue mode by the controller 10, and the tape 24 is fast forwarded or rewound. (step 512).

At this time, the password signal recorded on the magnetic tape 24 is read out by the password signal recording/reproducing head 9, and the password comparison unit 11 compares the read password with the password inputted from the input means 33.Step 5
13) If they match, the tape 24 is immediately stopped by a command from the system controller IO, and the mode changes to playback mode.

At the same time, the head for detecting the rotation of the drum 23A switches to the PG head 8 which records sound at a phase 180 degrees different from that of the normal PG head 3, and the control signal reproduced by the control head 7 and the PG head 8 The phase comparison circuit 4 compares the phase with the output signal of the drum 23A, and the control circuit 5 controls the rotational phase of the drum 23A based on the comparison result.

In this way, the azimuth of the signal recorded with the azimuth reversed during recording is also reproduced with the azimuth reversed (step 514), so that the reproduced video signal passes through the video signal processing circuit 24 and is normally reproduced. External output terminal 1 as a signal of
2 to the image display (step 515). If a matching password signal is not detected in step 513, the process searches the tape and then stops (step 516).

Note that if a password is not input from the password input means 33, playback is performed as usual, and the PG head 3
Since the phase of the drum 23A is controlled by , the portion recorded by password input will be played back with a head with a different azimuth, and no video output will be obtained.

Note that in this embodiment described above, two PC heads were installed on the drum to perform azimuth reversal, but the circuit is not limited to this, and the circuit can be modified by using a delay circuit to delay the control signal or the output of the PG head. You may also use a method of shifting the timing above. Further, the phase shift of the output of the PG head is not limited to 180°, but even if it is, for example, 90°, half of the signals cannot be reproduced normally, and depending on the type and form of the signal, confidential signals can be protected. Furthermore, the confidential signal is not limited to a video signal, and the present invention can be similarly applied to audio signals and the like.

[Effects of the Invention] As described above, according to the present invention, the azimuth can be recorded with at least a portion of the azimuth reversed in response to the input of a password at the time of recording, so that confidential signals can be protected. Also, during playback, normal playback is possible only when a password that matches the recorded password is entered, and if the correct password is not entered, the playback signal is distorted. As described above, according to the present invention, it is possible to easily record and reproduce confidential signals.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the circuit configuration of the recording system according to the embodiment of the present invention, FIG. 2 is a flowchart showing the operation of the circuit of FIG. 1 during recording, and FIG. 3 is a circuit diagram of the reproduction system according to the embodiment of the present invention. FIG. 4 is a flowchart showing the operation of the circuit of FIG. 3 during reproduction. 3... Normal PG head, 4... Phase comparison circuit, 6... Control signal recording circuit, 7... Control head, 8... PG head for phase inversion, 9... Password signal recording Reproduction head, 10... System controller, 11... Password comparison unit, 22.33... Password input means, 23A... Tram, 24... Drum motor. Figure 1

Claims (1)

[Claims] 1) A magnetic recording device that records signals by sequentially using a plurality of magnetic heads with different azimuths, comprising means for inputting a password, means for recording the password, and each of the magnetic heads. A magnetic recording device comprising: means for recording a control signal of a frequency corresponding to a recording cycle of the magnetic recording head; and means for shifting the recording phase of the plurality of magnetic heads with respect to the control signal in response to input of the password. Device. 2) A magnetic reproducing device that reproduces a signal by sequentially using a plurality of magnetic heads with different azimuths, comprising means for inputting a password, means for reproducing a recorded password, and reproduction of the input password. means for reproducing a control signal recorded at a frequency corresponding to the recording period of each of the magnetic heads; and the control signal reproduced according to the output of the comparing means. A magnetic reproducing apparatus comprising means for shifting the reproducing phase of the plurality of magnetic heads relative to the magnetic head.